METHOD FOR CONTROLLING THE PLANEITY OF A POLYMERIC STACK

专利摘要:
The invention relates to a method for controlling the flatness of a polymeric stack, said stack comprising at least a first and a second (co-) polymer layer (20, 30) stacked one on the other, the first an underlying (co) polymer layer (20) having not undergone any prior treatment for its crosslinking, at least one of the (co-) polymer layers being initially in a liquid or viscous state, said method being characterized in that the upper layer (30), called top coat (TC) is deposited on the first layer (20) in the form of a pre-polymer composition (pre-TC), comprising at least one monomer (s) and / or dimer (s) and / or oligomer (s) and / or polymer (s) in solution, and in that it is then subjected to a heat treatment capable of causing a crosslinking / polymerization reaction of the molecular chains within said layer (30, TC).
公开号:FR3074179A1
申请号:FR1761180
申请日:2017-11-24
公开日:2019-05-31
发明作者:Xavier Chevalier
申请人:Arkema France SA；
IPC主号:

专利说明:

METHOD OF CONTROLLING THE PLANEITY OF A POLYMERIC STACK [Field of the Invention] The present invention relates to the field of polymeric stacks.
More particularly, the invention relates to a method for controlling the flatness of such stacks. The invention also relates to a process for manufacturing a nano-lithography mask from such a stack, the flatness of which is controlled, and a polymeric stack obtained by said flatness control process.
Polymer stacks are used in a multitude of industrial applications among which we can cite, by way of non-exhaustive example, the production of coatings for the aerospace or aeronautics or automotive or wind power industries. , inks, paints, membranes, biocompatible implants, packaging materials, or even optical components, such as optical filters for example, or microelectronic or optoelectronic components or microfluidic components. The invention is addressed to all applications whatever they are, since the stack comprises at least two polymeric materials stacked one on the other.
Among the various possible industrial applications, the invention is also concerned, and in a non-exhaustive manner, with applications dedicated to the field of organic electronics, and more particularly with applications of nano-lithography by directed self-assembly. , also called DSA (from the acronym "Directed Self-Assembly"), for which other requirements must be met concomitantly.
The prior art and stability of thin polymer films on a solid substrate or on an underlying layer, itself solid or liquid, are technologically important in certain industrial applications such as, for example, the surface protection, the production of coatings for the aerospace or aeronautics or automotive or wind power industries, paints, inks, the manufacture of membranes, or even microelectronic and optoelectronic and microfluidic components.
Ref: 0560-ARK89 [0006] Polymer-based materials have so-called low surface energy interfaces, where molecular chains therefore have relatively low cohesion energy, compared with other solid interfaces such as surfaces 'oxides or metals having a significantly higher surface energy, therefore less likely to be deformable under the effect of any force.
[0007] In particular, the phenomenon of dewetting a polymer film deposited in the liquid or viscous state on the surface of an underlying layer, itself in the solid or liquid state, has been known for a long time. The term “liquid or viscous polymer” is understood to mean a polymer having, at a temperature above the glass transition temperature, due to its rubbery state, an increased capacity for deformation due to the possibility given to its molecular chains to move freely. . The hydrodynamic phenomena at the origin of dewetting appear as long as the material is not in a solid state, that is to say undeformable due to the negligible mobility of its molecular chains. This dewetting phenomenon is characterized by the spontaneous removal of the polymer film applied to the surface of the underlying layer, when the initial system is left free to evolve over time. There is then a loss of continuity of the initial film and a variation in thickness. The film does not spread and forms one or more spherical caps / droplets revealing a non-zero contact angle with the underlying surface. This phenomenon is illustrated in Figures 1A to 1C. FIG. 1A represents more particularly a solid substrate 10, on which is deposited a layer of polymer 20 in the liquid or viscous state. In this first case, the stacking system is in a "liquid / solid" configuration. After the deposition of such a polymer layer 20, the dewetting phenomenon appears and the polymer 20 no longer spreads correctly on the surface of the substrate 10, forming spherical caps and resulting in a stack whose surface is not flat. . FIG. 1B represents a solid substrate 10, on which a first layer of polymer 20 is deposited, this first layer being solidified at the time of deposition of a second upper polymer layer 30. In this case, the second polymer layer 30 to the upper surface is deposited in a liquid or viscous state on the solid surface of the first layer of polymer 20. It is said that the interface between the two layers of polymer is in a configuration
Ref: 0560-ARK89 "liquid / solid". In this case too, after a certain time, a dewetting phenomenon occurs and the polymer 30 does not spread correctly on the surface of the first polymer layer 20, forming spherical caps and resulting in a stack whose surface n is not flat. Finally, FIG. 1C represents a solid substrate 10, on which is deposited a first layer of polymer 20 in the liquid or viscous state, itself covered with a second layer of polymer superior 30 in the liquid or viscous state. In this case, the interface between the two layers of polymer is in a "liquid / liquid" configuration. In this case also, the second upper layer 30 of polymer does not spread correctly on the surface of the first polymer layer 20, it can also optionally dissolve in part in the first polymer layer 20, causing a phenomenon of inter- diffusion at the interface between the two layers. This layer 30 then deforms, inter alia under the combined effect of gravity, of its own density, of its surface energy, of the viscosity ratio between the materials of the polymer layers 30 and 20 in presence, as well as under the effect of Van der Waals interactions leading to the amplification of the capillary waves of the system. This deformation leads to the production of a discontinuous film 30, further comprising spherical caps, and also deforming the first underlying polymer layer 20. This therefore results in a stack whose surface is not flat and whose interface between the two layers of polymer is not clear.
The spreading coefficient of a liquid or viscous layer, noted S, is given by Young's equation below:
S = Yc - (Ycl + Yl), in which y _c represents the surface energy of the underlying layer, solid or liquid, y _l represents the surface energy of the upper layer of liquid polymer and ycl represents l energy at the interface between the two layers. The term surface energy (denoted γ _χ ) of a given material “x” is understood to mean the excess energy at the surface of the material compared to that of the material taken as a mass. When the material is in liquid form, its surface energy is equivalent to its surface tension. When the spreading coefficient S is positive, then the wetting is total and the liquid film spreads completely over the surface of the underlying layer. When the spreading coefficient S is negative, then the wetting is partial, that is to say that the film does not spread completely over the surface of the underlying layer and
Ref: 0560-ARK89 there is a dewetting phenomenon if the initial stacking system is left free to evolve.
In these stacking systems of layer (s) of polymer materials, in which the configurations can for example be “liquid / solid” or “liquid / liquid”, the surface energies of the different layers can be very different, thus making the entire system metastable or even unstable due to the mathematical formulation of the spreading parameter S.
When a stacking system, deposited on any substrate, comprises different layers of polymeric material in the liquid / viscous state, stacked on each other, the stability of the entire system is governed by the stability of each layer at the interface with different materials.
For this kind of metastable or even unstable liquid / liquid system, dewetting phenomena were observed during the relaxation of the initial stresses, independently of the nature of the materials involved (small molecules, oligomers, polymers) . Different studies (F. Brochart-Wyart & al., Langmuir, 1993, 9, 3682-3690; C. Wang & al., Langmuir, 2001, 17, 6269-6274; M. Geoghegan & al., Prog. Polym. Sci. , 2003, 28, 261-302) have demonstrated and explained theoretically and experimentally the behavior as well as the origin of the dewetting observed. Whatever the mechanisms (spinodal decomposition or nucleation / growth), this type of liquid / liquid system tends to be particularly unstable and leads to the introduction of severe defects in the form of discontinuity of the film of interest, c that is to say in the example of FIG. 1C the first polymer layer 20, the initial flatness of which is disturbed, with the appearance, in the best of cases, of holes in the film or the double layer of polymer films thus rendering it unusable for the intended applications.
Dewetting is a thermodynamically favorable phenomenon, materials spontaneously seeking to minimize the contact surface with each other as much as possible. However, for all the applications referred to above, it is precisely sought to avoid such a phenomenon, in order to have perfectly flat surfaces. We also seek to avoid the phenomena of inter-diffusion between the layers in order to obtain clear interfaces.
A first problem that the applicant has sought to solve therefore consists in avoiding the appearance of dewetting phenomena in the
Ref: 0560-ARK89 polymer stack systems, at least one of the polymers of which is in a liquid / viscous state, whatever the polymers in the system and whatever the intended applications.
A second problem that the applicant has sought to solve consists in avoiding the phenomena of inter-diffusion at the interfaces, in order to obtain clear interfaces.
In the particular context of applications in the field of nanolithography by directed self-assembly, or DSA, block copolymers, capable of nanostructuring at an assembly temperature, are used as nano masks -lithography. For this, stacking systems of liquid / viscous materials are also used. These stacks comprise a solid substrate, on which is deposited at least one block copolymer film, denoted BCP below. This BCP block copolymer film, intended to form a nanolithography mask, is necessarily in a liquid / viscous state at the assembly temperature, so that it can self-organize into nano-domains, from made of phase segregation between blocks. The block copolymer film thus deposited on the surface of the substrate is therefore subject to dewetting phenomena when it is brought to its assembly temperature.
In addition, for the intended application, such a block copolymer must also preferably have nano-domains oriented perpendicular to the lower and upper interfaces of the block copolymer, in order to then be able to selectively remove one of the blocks from the copolymer with blocks, create a porous film with the residual block (s) and transfer, by etching, the patterns thus created to the underlying substrate.
However, this condition of perpendicularity of the patterns is fulfilled only if each of the lower (substrate / block copolymer) and upper (block copolymer / ambient atmosphere) interfaces is “neutral” with respect to each of the blocks of said BCP copolymer, that is to say that there is no preponderant affinity of the interface considered for at least one of the blocks constituting the BCP block copolymer.
With this in mind, the possibilities for controlling the affinity of the so-called "lower" interface, located between the substrate and the block copolymer, are well known and mastered today. There are two main techniques for
Ref: 0560-ARK89 to control and guide the orientation of the blocks of a block copolymer on a substrate: graphoepitaxy and / or chemistry-epitaxy. Graphoepitaxy uses a topological constraint to force the block copolymer to organize itself in a predefined and commensurable space with the periodicity of the block copolymer. For this, graphoepitaxy consists of forming primary patterns, called guides, on the surface of the substrate. These guides, of any chemical affinity for the blocks of the block copolymer, delimit zones within which a layer of block copolymer is deposited. The guides are used to control the organization of the blocks of the block copolymer to form secondary patterns of higher resolution, within these zones. Classically, the guides are formed by photolithography. By way of example, among the possible solutions, if the intrinsic chemistry of the monomers constituting the block copolymer allows it, a random copolymer comprising a judiciously chosen ratio of the same monomers as those of the BCP block copolymer can be grafted onto the substrate, thus making it possible to balance the initial affinity of the substrate for the BCP block copolymer. This is for example the classic choice method used for a system such as PS-b-PMMA and described in the article by Mansky et al, Science, 1997, 275,1458). Chemistry-epitaxy uses a contrast in chemical affinities between a pre-drawn pattern on the substrate and the different blocks of the block copolymer. Thus, a pattern having a strong affinity for only one of the blocks of the block copolymer is pre-drawn on the surface of the underlying substrate, in order to allow the perpendicular orientation of the blocks of the block copolymer, while the rest of the surface has no particular affinity for the blocks of the block copolymer. For this, a layer is deposited on the surface of the substrate comprising on the one hand, neutral zones (consisting for example of grafted random copolymer), having no particular affinity with the blocks of the block copolymer to be deposited and of on the other hand, affine zones (consisting for example of grafted homopolymer of one of the blocks of the block copolymer to be deposited and serving as an anchoring point for this block of the block copolymer). The homopolymer serving as an anchor point can be made with a width slightly greater than that of the block with which it has a preferential affinity and allows, in this case, a “pseudo-equitable” distribution of the blocks of the block copolymer at the substrate surface. Such a layer is called “pseudo-neutral” because it allows a distribution
Ref: 0560-ARK89 fair or "pseudo-fair" blocks of the block copolymer on the surface of the substrate, so that the layer does not, as a whole, have preferential affinity with one of the blocks of the copolymer blocks. Consequently, such a chemistry-epitaxial layer on the surface of the substrate is considered to be neutral with respect to the block copolymer.
On the other hand, control of the so-called "upper" interface of the system, that is to say the interface between the block copolymer and the surrounding atmosphere, remains today much less well controlled. Among the different approaches described in the prior art, a first promising solution, described by Bâtes et al in the publication entitled “Polarity-switching top coats enable orientation of sub-10nm block copolymer domains”, Science 2012, Vol.338, p .775 - 779 and in document US2013 280497, consists in controlling the surface energy at the upper interface of a nano-structured block copolymer, of poly (trimethylsilystyrene-b-lactide) type, denoted PTMSS-b -PLA, or poly (styrene-b-trimethylsilystyrene-b-styrene), denoted PS-bPTMSS-b-PS, by the introduction of an upper layer, also called “top coat” and denoted TC thereafter, deposited on the surface of the block copolymer. In this document, the polar top coat is deposited by spinning (or “spin coating” in English terminology) on the block copolymer film to be nanostructured. The top coat is soluble in an acidic or basic aqueous solution, which allows its application on the upper surface of the block copolymer, which is insoluble in water. In the example described, the top coat is soluble in an aqueous solution of ammonium hydroxide. The top coat is a random or alternating copolymer, the composition of which comprises maleic anhydride. In solution, the opening of the maleic anhydride cycle allows the top coat to lose ammonia. At the time of the self-organization of the block copolymer at the annealing temperature, the maleic anhydride cycle of the top coat closes, the top coat undergoes a transformation in a less polar state and becomes neutral compared to the copolymer at blocks, thus allowing a perpendicular orientation of the nanodomains with respect to the two lower and upper interfaces. The top coat is then removed by washing in an acidic or basic solution.
In such systems, based on stacks noted TC / BCP / substrate, the TC top coat, applied by spin coating, has a liquid / viscous state. The BCP block copolymer is furthermore necessarily in its liquid / viscous state,
Ref: 0560-ARK89 in order to be able to self-organize at assembly temperature and create the desired patterns. However, in the same way as for any polymeric stack, the application of such a top coat layer TC, in the liquid or viscous state, on a layer of BCP block copolymer itself in the liquid state or viscous, causes the appearance, at the upper block copolymer / top coat (BCP / TC) interface, of the same dewetting phenomenon as that described above with reference to FIG. 1C. Indeed, because of hydrodynamic phenomena leading to the amplification of capillary waves of the TC top coat layer and of its interaction with the underlying layer of BCP block copolymer, this type of stacking tends to be particularly unstable and leads to the introduction of severe defects in the form of discontinuity of the BCP block copolymer film, thus making it unsuitable for use, for example, as a nano-lithography mask for electronics. In addition, the finer the deposited polymer film, that is to say at least once the radius of gyration of a molecular chain of the polymer considered, the more it will tend to be unstable or metastable, all the more when the surface energy of the underlying layer is different from that of said polymer and the system is left free to evolve. Finally, the instability of the polymer film deposited on the underlying layer is in general all the more important the higher the "annealing temperature / annealing time" couple.
Regarding the first solution described by Bâtes et al, just after the step of depositing the TC top coat layer by spin-coating, there remains solvent trapped in the polymer chains, as well as an "open" form maleate ", less rigid, of the monomer. These two parameters imply, in fact, a plasticization of the material and therefore a significant decrease in the glass transition temperature (Tg) of the material before thermal annealing allowing the return of said material to the anhydride form. In addition, the difference between the assembly temperature of the BCP block copolymer (which is 210 ° C for the PS-b-PTMSS-b-PS block copolymer and 170 ° C for the PTMSS block copolymer -b-PLA) with respect to the glass transition temperature of the TC top coat layer (which is respectively 214 ° C. for the TC-PS top coat deposited on the block copolymer of PS-b-PTMSS-b- PS and 180 ° C for the TC-PLA top coat deposited on the PTMSS-b-PLA block copolymer) is too low to be able to guarantee the absence of dewetting phenomenon. Finally, the assembly temperature also does not guarantee kinetics
Ref: 0560-ARK89 of correct assembly for the formation of patterns in the context of the targeted DSA application.
In addition, still concerning the solution described by Bâtes & al., To avoid the problem of inter-diffusion or solubilization of the TC top coat layer in the underlying BCP block copolymer, the transition temperature glassy Tg of the TC top coat layer must be high and higher than the assembly temperature of the block copolymer. For this, the constituent molecules of the top coat layer TC, are chosen so as to have a high molecular weight.
The molecules constituting the TC top coat must therefore have a high glass transition temperature Tg, as well as long molecular chains, in order to limit the solubilization of the TC top coat layer in the BCP block copolymer. and avoid the appearance of a dewetting phenomenon. These two parameters are particularly restrictive in terms of synthesis. Indeed, the top coat layer TC must have a sufficient degree of polymerization so that its glass transition temperature Tg is much higher than the assembly temperature of the underlying block copolymer. In addition, the possible choice of co-monomers, making it possible to vary the intrinsic surface energy of the TC top coat layer so that the latter has a neutral surface energy with respect to the sub-block copolymer. jacent, is limited. Finally, in their publication, Bâtes et al describe the introduction of co-monomers to stiffen the chains. These added co-monomers are rather carbon-based monomers, norbornene type, which do not promote correct solubilization in polar / protic solvents.
On the other hand, for the proper functioning of such stacked polymer systems intended for applications in the field of nano-lithography by directed self-assembly, not only the phenomena of dewetting and interdiffusion must be avoided in order to satisfy the conditions of surface flatness and clear interface, but in addition, additional requirements must be satisfied in order to allow in particular the obtaining of a perfect perpendicularity of the nano-domains of the block copolymer after assembly.
Among these additional requirements to be satisfied, the TC top coat layer must be soluble in a solvent, or solvent system, in which the BCP block copolymer itself is not soluble, under penalty of re-dissolving the
Ref: 0560-ARK89 ίο block copolymer at the time of the top coat layer deposition, the deposition of such a layer being generally carried out by the well-known spin coating technique. Such a solvent is also known as “solvent orthogonal to the block copolymer”. It is also necessary that the top coat can be easily removed, for example by rinsing in an appropriate solvent, preferably itself compatible with standard electronic equipment. In the publication by Bâtes et al cited above, the authors circumvent this point by using, as the main base of the polymer chain constituting the TC top coat, a monomer (maleic anhydride) whose polarity changes once in basic aqueous solution ( with the introduction of charges into the chain by acid-base reaction), then returns to its initial uncharged form once the material has been deposited and then annealed at high temperature.
A second requirement lies in the fact that the TC top coat layer must preferably be neutral with respect to the blocks of the BCP block copolymer, that is to say that it must have an equivalent interfacial tension for each of the different blocks of the block copolymer to be nano-structured, at the time of the heat treatment allowing the structuring of the BCP block copolymer, in order to guarantee the perpendicularity of the patterns with respect to the interfaces of the block copolymer film. Given all the aforementioned difficulties, the chemical synthesis of the top-coat material can prove to be a challenge in itself. Despite the difficulties in synthesizing such a top coat layer and the dewetting and interdiffusion phenomena to be avoided, the use of such a layer appears to be a priori essential for orienting the nano-domains of a copolymer with blocks perpendicular to the interfaces.
In a second solution described in the document by J. Zhang & al., Nano Lett., 2016, 16, 728-735, as well as in documents WO16193581 and WO16193582, a second block copolymer, BCP n ° 2, is used as a top coat layer, “embedded” with the first BCP block copolymer in solution. The BCP No. 2 block copolymer comprises a block having a different solubility, for example a fluorinated block, as well as a low surface energy, thus naturally allowing the segregation of the second BCPn ° 2 block copolymer on the surface of the first copolymer. after blocking and rinsing in an appropriate solvent, for example a fluorinated solvent. At least one
Ref: 0560-ARK89 of the blocks of the second block copolymer has, at the organizational temperature, a neutral surface energy with respect to all of the blocks of the first film of block copolymer to be organized perpendicularly. Like the first solution, this solution is also conducive to the appearance of dewetting phenomena.
In a third solution, described by HS Suh & al., Nature Nanotech., 2017, 12, 575-581, the authors deposit the TC top coat layer by the iCVD method (from the acronym "initiated Chemical Vapor Déposition ”), which allows them to overcome the problem of the solvent of the TC top coat at the time of deposition which must be“ orthogonal ”to the BCP block copolymer, that is to say non-solvent for the block copolymer PCO. However, in this case, the surfaces to be covered require special equipment (an iCVD chamber), and therefore involve a longer process time than with a simple spin-coating deposition. In addition, the ratios of different monomers to be reacted can vary from one iCVD chamber to another, so that it appears necessary to constantly make adjustments / corrections as well as quality control tests, in order to be able to use a such a process in the field of electronics.
The different solutions described above for producing a stack of polymer layers having a flat surface, with clear interfaces between the layers are not entirely satisfactory. In addition, when such a stack is intended for DSA applications, and comprise a film of block copolymer to be nano-structured with nano-domains which must be oriented perfectly perpendicular to the interfaces, the existing solutions generally remain too tedious and complex. to be implemented and do not make it possible to significantly reduce the defectiveness associated with dewetting and the non-perfect perpendicularity of the patterns of the block copolymer. The solutions considered also seem too complex to be compatible with industrial applications.
Therefore, in the context of the use of stacks comprising BCP block copolymers in the form of thin films, intended to be used as nanolithography masks, for applications in organic electronics, it is imperative to ability to check not only that the BCP block copolymer film covers the entire previously neutralized surface of the
Ref: 0560-ARK89 substrate considered without dewetting thereof, and that the top coat layer covers well the entire surface of the block copolymer without dewetting, but also that the top coat layer deposited at the upper interface does not have any preponderant affinity with any one of the blocks of the block copolymer, in order to guarantee the perpendicularity of the patterns with respect to the interfaces.
[Technical problem] The invention therefore aims to remedy at least one of the drawbacks of the prior art. The invention aims in particular to propose a method for controlling the flatness of a polymer stacking system, said method making it possible to avoid the appearance of dewetting phenomena of the stacked polymer layers, while at least one of the lower layers of the stack keeps the possibility of being in a liquid-viscous state depending on the temperature, as well as of phenomena of solubilization between the different layers and of inter-diffusion at the interfaces, so as to obtain stacks of which the layers are perfectly flat and whose interfaces between two layers are clear. The process must also be simple to implement and allow industrial execution.
The invention also aims to remedy other problems specific to applications dedicated to nano-lithography by directed self-assembly (DSA). In particular, it aims to allow the deposition of a top coat layer on the surface of a block copolymer, which avoids the appearance of the above-mentioned dewetting and interdiffusion phenomena and which also has an energy of neutral surface with respect to the blocks of the underlying block copolymer, so that the nano-domains of the block copolymer can orient themselves perpendicularly to the interfaces, at the assembly temperature of said block copolymer. It also aims to allow the deposition of such a top coat layer with a solvent which is orthogonal to the underlying block copolymer, that is to say not capable of attacking, even partially solvating or dissolving this -latest.
[Brief description of the invention] To this end, the invention relates to a method for controlling the flatness of a polymeric stack, said stack comprising at least a first and a second layer of (co-) polymer stacked on top of each other, the first underlying (co-) polymer layer having not undergone any prior treatment
Ref: 0560-ARK89 allowing its crosslinking, at least one of the (co-) polymer layers being initially in a liquid or viscous state, said process being characterized in that the upper layer, called top coat, is deposited on the first polymer layer in the form of a pre-polymer composition, comprising one or more monomer (s) and / or dimer (s) and / or oligomer (s) and / or polymer (s) in solution, and in that it is then subjected to a heat treatment capable of causing a crosslinking or polymerization reaction of the molecular chains within said layer.
Thus, the top coat layer polymerizes / crosslinks quickly to form a rigid network, so that it has neither the time nor the physical possibility of wetting. The upper layer thus crosslinked / polymerized makes it possible to solve several different technical problems described above. Firstly, this crosslinking / polymerization makes it possible to eliminate the dewetting inherent in the top coat layer, since the molecular movements of the top coat layer are very restricted once it is fully crosslinked / polymerized. Secondly, this crosslinking / polymerization of the upper layer also makes it possible to eliminate the typical dewetting possibilities known as “liquid-liquid” from the system, the top coat layer being able to be considered as a solid, possibly deformable, and no longer as a viscous fluid after crosslinking / polymerization and once the system has been brought to a temperature of use, higher than the glass transition temperature of the underlying polymer layer. Third, the crosslinked / polymerized top coat layer also helps stabilize the underlying polymer layer so that it does not wilt from its substrate. Another remarkable and non-negligible point is that the step of chemical synthesis of the material of the top coat layer is facilitated because it makes it possible to overcome the problems linked to the need to synthesize a material of high molecular mass, thus offering a better control over the final architecture of the material (composition, mass, etc.) as well as significantly less drastic synthesis operating conditions (permissible impurity rate, solvent, etc.) than in the case of materials with large molecular weights . Finally, the use of small molecular weights for the upper layer makes it possible to widen the range of possible orthogonal solvents for this material. It is indeed well known that
Ref: 0560-ARK89 polymers with small masses are easier to dissolve than polymers with the same chemical composition having large masses.
According to other optional characteristics of the method for controlling the flatness of a polymeric stack:
the heat treatment consists in heating the stack in a temperature range between 0 ° C and 350 ° C, preferably between 10 ° C and 300 ° C and more preferably between 20 and 150 ° C, for a time preferably less than 15 minutes, more preferably less than 10 minutes and more preferably less than 5 minutes;
the pre-polymer composition is a composition formulated in a solvent, or used without solvent, and which comprises at least one monomer, dimer, oligomer or polymer chemical entity, or any mixture of these different entities, of a chemical nature in whole or identical part, and each comprising at least one chemical function capable of ensuring the crosslinking / polymerization reaction under the effect of a thermal stimulus;
- The pre-polymer composition further comprises a thermally activatable catalyst, chosen from radical generators, or acid generators, or even basic generators;
- at least one of the chemical entities of the prepolymer composition has at least one fluorine and / or silicon and / or germanium atom, and / or an aliphatic carbon chain of at least two carbon atoms in its chemical formula ;
the prepolymer composition also comprises in its formulation: a chemical entity chosen from an antioxidant, a base or a weak acid, capable of trapping said chemical entity capable of initiating the crosslinking / polymerization reaction, and / or one or more additives making it possible to improve wetting and / or adhesion, and / or the uniformity of the top layer of top coat deposited on the underlying layer, and / or one or more additives making it possible to absorb a or several ranges of light radiations of different wavelength, or to modify the electrical conductivity properties of the prepolymer;
- the crosslinking / polymerization reaction is obtained by radical route, or by ionic route (cationic or anionic), or results from a reaction of
Ref: 0560-ARK89 condensation or addition (for example, Michael addition) between two derivatives having chemical functions compatible with each other;
- when the polymerization is radical, the monomer (s) and / or dimer (s) and / or oligomer (s) and / or polymer (s) constituting the pre-polymer layer, is (are ) chosen from derivatives comprising unsaturations in their chemical structure, chosen from derivatives of the acrylate or methacrylate or vinyl type;
- more particularly, the monomer (s) and / or dimer (s) and / or oligomer (s) and / or polymer (s) constituting the pre-polymer layer, are chosen from the list not exhaustive derivatives of acrylates or di- or tri-acrylates or multiacrylates, methacrylate, or multi-methacrylates, or polyglycidyl or vinyl, fluoroacrylates or fluoromethacrylates, vinyl fluorides or fluorostyrene, acrylate or methacrylate, acrylate or hydroxyalkyl methacrylate, alkylsilyl acrylate or methacrylate, unsaturated esters / acids such as fumaric or maleic acids, vinyl carbamates and carbonates, allyl ethers, and thiol-ene systems;
when the polymerization / crosslinking is carried out by a radical route, the prepolymer composition also comprises a thermally activatable catalyst, chosen from derivatives of the organic peroxide type, or alternatively derivatives comprising a chemical function of the azo type such as azobisisobutyronitrile, or alternatively derivatives of alkyl halide type;
- when the polymerization is cationic, the monomer (s) and / or dimer (s) and / or oligomer (s) and / or polymer (s) constituting the pre-polymer layer, are derivatives comprising chemical functions of epoxy / oxirane type, or vinyl ethers, cyclic ethers, thiirane, thietanes, trioxane, vinyls, lactones, lactams, carbonates, thiocarbonates, maleic anhydride;
when the polymerization / crosslinking is carried out cationically, the prepolymer composition also comprises a thermally activatable catalyst, chosen from chemical derivatives making it possible to generate a thermally activated acid proton, such as ammonium salts such as triflate or ammonium trifluoroacetate, phosphoric or sulfuric or sulfonic acids, or onium salts such as iodonium or phosphonium salts, or also imidazolium salts;
Ref: 0560-ARK89
- when the polymerization / crosslinking results from a condensation / addition, the monomer (s) and / or dimer (s) and / or oligomer (s) and / or polymer (s) constituting the layer pre-polymer can be chosen, in a non-exhaustive or limiting manner for the invention, from the combination systems between a thiol or polythiol derivative and an epoxy, thiol / nitrile, thiol / vinyl derivative, or even between a derivative of silane or organosilane or halosilane type and a hydroxy or amino derivative, or alternatively between an amine or polyamine derivative and an isocyanate, amine / epoxy, amine / aldehyde, amine / ketone derivative;
- when the polymerization is anionic, the monomer (s) and / or dimer (s) and / or oligomer (s) and / or polymer (s) constituting the pre-polymer layer, are derivatives alkyl cyanoacrylates, epoxides / oxiranes, acrylates, or derivatives of isocyanates or polyisocynanates;
- when the monomer (s) and / or dimer (s) and / or oligomer (s) and / or polymer (s) constituting the pre-polymer layer, are cyanoacrylate type derivatives of alkyl, the crosslinking / polymerization reaction can be spontaneous at room temperature and / or be catalyzed by ambient humidity.
According to a first preferred form of the invention, the prepolymer composition comprises a mixture of monomer (s) and / or dimer (s) and / or oligomer (s) and / or polymer (s), where each entity comprises one or more chemical functions making it possible to ensure said crosslinking / polymerization reaction, as well as a reaction catalyst and / or a multitopic / multifunctional reagent allowing an addition or condensation reaction. More particularly, the prepolymer composition comprises a mixture of monomer (s) and / or dimer (s) and / or oligomer (s) and / or polymer (s), preferably comprising epoxy / oxirane functions, and a catalyst making it possible to generate an acid and / or a co-reactant making it possible to carry out an addition reaction on the epoxy functions.
According to this first preferred form of the invention:
- The catalyst is chosen from at least one of the following compounds: amines or polyamines, such as diethylene triamine (DTA), isophorone diamine (IPD), 4,4'-diaminodiphenylsulfone (DDS), hexamethylene diamine (HMDA), dicyandiamide (cyanoguanidine), or ammonium salts, such as
Ref: 0560-ARK89 ammonium triflate or ammonium trifluoroacetate, or ascorbic acid and its derivatives, chosen from sodium or magnesium ascorbate or sodium, magnesium or ammonium ascorbyl phosphate, as well as the various isomers (diastereoisomers, enantiomers) possible of ascorbic acid; uric acid; phenol, polyphenols and phenolic derivatives such as hydroquinone, resorcinol, 2,4-pentanedione, malonaldéhyde (propanedial), tartronaldéhyde (2hydroxypropanedial), furanone and more generally reductones;
- the co-reagent, for its part, is chosen from at least one of the following reagents: thiols or polythiols such as pentaerythritoltetrakis (3mercaptopropionate); imidazoles and imidazolium derivatives; acid anhydrides, such as, for example, succinic anhydride or even maleic anhydride; hydrazines;
- The catalyst and / or the co-reactant is introduced into the pre-polymer composition with a mass content less than or equal to 80% of the total dry weight of the composition.
According to a second preferred form of the invention:
the prepolymer composition comprises a mixture of one or more multifunctional acrylic monomer (s), of cyanoacrylate type, capable of generating a polymerization / crosslinking reaction spontaneously at ambient or moderate temperature, in the presence of ambient humidity ;
the cyanoacrylate type monomers are chosen from at least one of the following compounds: alkyl cyanoacrylate, linear or branched, such as methyl cyanoacrylate, ethyl cyanoacrylate, butyl cyanoacrylate, or cyanoacrylate octyl, neopentyl cyanoacrylate, octadecyl cyanoacrylate, or alternatively 2ethylphenyl cyanoacrylate, or alternatively alkylalkoxy cyanoacrylate, such as 2-ethoxylethyl cyanoacrylate, or tetrahydrofurfuryl cyanoacrylate, or cyanouryl cyanoacrylate .
According to still other optional characteristics of the method for controlling the flatness of a polymeric stack:
the crosslinking / polymerization temperature of the layer of prepolymer composition is lower than the glass transition temperature Tg of the
Ref: 0560-ARK89 first layer of polymer and the highest glass transition temperature Tg of the first layer of polymer is greater than 25 ° C;
the pre-polymer composition (pre-TC) further comprises a solvent chosen from solvents or mixtures of solvents whose Hansen solubility parameters are such that δ _ρ > 10 MPa ^1/2 and / or ôh ^ 10 MPa ^{1 / 2} , and with ôd <25 MPa ^1/2 ;
- More particularly, the solvent is chosen from alcoholic solvents such as methanol, ethanol, isopropanol, 1-methoxy-2-propanol, hexafluoroisopropanol; or water; dimethyl sulfoxide (DMSO); dimethylformamide; acetonitrile; diols such as ethylene glycol or propylene glycol; dimethylacetamide, gammabutyrolactone, ethyl lactate or a mixture thereof;
- The first polymer layer is in a solid state when the stack is brought to a temperature below its glass transition temperature or in a liquid-viscous state when the stack is brought to a temperature above its glass transition temperature or at its highest glass transition temperature;
the first polymer layer is a block copolymer capable of nanostructuring at an assembly temperature, said block copolymer being deposited on an underlying layer whose surface is previously neutralized, said assembly temperature being less than a temperature at which the top coat material behaves like a viscoelastic fluid, said temperature being higher than the glass transition temperature of said top coat material and preferably, said assembly temperature is lower than the glass transition temperature of the layer top coat in its crosslinked / polymerized form;
- The underlying layer may or may not have patterns, said patterns being predrawn by a step or a sequence of lithography steps of any kind prior to the step of depositing the first layer of block copolymer, said patterns being intended guiding the organization of said block copolymer by a technique called chemistry-epitaxy or graphoepitaxy, or a combination of these two techniques, in order to obtain a neutralized or pseudo-neutralized surface;
Ref: 0560-ARK89
- the block copolymer comprises silicon in one of its blocks;
- When the prepolymer composition comprises a mixture of one or more multifunctional acrylic monomer (s), of cyanoacrylate type, the crosslinking temperature of the layer of prepolymer composition is lower than the glass transition temperature Tg la higher of the block copolymer layer and the block copolymer has at least one block of which at least 40% of the composition has a glass transition temperature above 25 ° C;
- The first layer of block copolymer is deposited on a thickness at least equal to 1.5 times the minimum thickness of the block copolymer;
- The prepolymer composition comprises a mixture of monomers and / or dimers and / or oligomers and / or polymers all carrying the same chemical functions ensuring crosslinking and each carrying different chemical groups;
- the composition of the pre-polymer layer also comprises plasticizers and / or wetting agents, added as additives;
- The composition of the pre-polymer layer further comprises rigid comonomers chosen from derivatives comprising either one / more aromatic ring (s) in their structure, or mono or multicyclic aliphatic structures, and having one / more functions (s) chemical (s) suitable for the crosslinking / polymerization reaction targeted; and more particularly norbornene derivatives, isobornyl acrylate or methacrylate, styrenic, anthracene derivatives, adamantyl acrylate or methacrylate.
The invention further relates to a process for manufacturing a nano-lithography mask from a polymeric stack obtained in accordance with the process which has just been described above, characterized in that once the crosslinked top coat layer, the stack is subjected to annealing for a determined period, at the assembly temperature of the block copolymer so that it becomes nanostructured.
According to other optional characteristics of this process:
- after the nano-structuring step of the block copolymer, the top coat layer is removed in order to leave a film of nanostructured block copolymer of minimum thickness, then at least one of the blocks of said block copolymer,
Ref: 0560-ARK89 oriented perpendicular to the interfaces, is removed to form a porous film capable of serving as a mask for nano-lithography;
- When the block copolymer is deposited on a thickness greater than the minimum thickness, an additional thickness of said block copolymer is removed simultaneously or successively with the removal of the top coat layer, in order to leave a film of nano-structured block copolymer d the minimum thickness (e), then at least one of the blocks of said block copolymer, oriented perpendicular to the interfaces, is removed in order to form a porous film capable of serving as a mask for nano-lithography;
the top coat layer and / or the excess thickness of the block copolymer and / or the block (s) of the block copolymer is / are removed by dry etching;
- The etching steps of the top coat layer and / or of the extra thickness of the block copolymer and of one or more blocks of the block copolymer, are carried out successively in the same etching frame, by plasma etching;
- at the time of the crosslinking / polymerization step of the top coat layer, the stack is subjected to a localized heat treatment, on certain areas of the top coat layer, in order to create crosslinked / polymerized areas of top coat and uncrosslinked / unpolymerized areas;
- the localized heat treatment is carried out by means of an infrared laser or by means of a so-called broadband light irradiation, where a set of wavelengths is used rather than a restricted range in the case of laser type radiation, or via mechanical means such as a heating tip of an atomic force microscope, or even via a “roll-to-roll” type process, where a heated nanostructured roller is brought into contact with the surface polymer by printing;
- in the context of the manufacture of a nano-lithography mask by directed assembly, the crosslinked / polymerized areas of top coat preferably, but not limiting for the invention, have a neutral affinity with respect to the sub-block copolymer jacent, while the affinity of the non-crosslinked / unpolymerized top coat zones with respect to the blocks of the underlying block copolymer is not neutral;
Ref: 0560-ARK89
- after the localized heat-crosslinking of the top coat layer, the stack is rinsed with the solvent which has allowed the deposition of the pre-polymer layer in order to remove the non-crosslinked / non-polymerized areas;
another pre-polymer material, which is not neutral with respect to the underlying block copolymer, is deposited in the areas not previously heat treated and devoid of a top coat layer, then said non-neutral prepolymer material is subjected to a localized heat treatment in order to crosslink / polymerize at predefined locations;
- at the time of the annealing step of the stack at the assembly temperature of the block copolymer, nano-domains are formed perpendicular to the interfaces in zones located opposite the zones of the neutral and crosslinked top coat layer / polymerized, and nano-domains parallel to the interfaces in areas of the block copolymer located opposite the areas lacking a crosslinked / polymerized neutral top coat layer.
The invention finally relates to a polymeric stack comprising at least two layers of polymer stacked one on the other, characterized in that the upper layer, called top coat, deposited on the first polymer layer is obtained by in situ crosslinking in accordance with the method described above, said stack being intended to be used in applications chosen from the production of coatings for the aerospace or aeronautics or automotive or wind power industries, inks, paints , membranes, biocompatible implants, packaging materials, or even optical components, such as optical filters, or microelectronic or optoelectronic or microfluidic components.
More particularly, this stack is intended for applications in the field of nano-lithography by directed self-assembly, the first polymer layer is a block copolymer and the surfaces of the layer on which the block copolymer is deposited and the top coat layer have a neutral surface energy with respect to the blocks of the block copolymer.
Other features and advantages of the invention will appear on reading the description given by way of illustrative and nonlimiting example, with reference to the appended figures which represent:
Ref: 0560-ARK89 • Figures 1A to 1 C, already described, diagrams seen in section of different stacks of polymers and their evolution over time, • Figure 2, already described, a diagram seen in section of a stack of polymers according to the invention, not undergoing any dewetting or inter-diffusion phenomenon, FIG. 3, a diagram seen in section of a stack according to the invention dedicated to an application in nano-lithography by self- directed assembly (DSA) for the production of a nano-lithography mask.
[Detailed description of the invention] By "polymers" is meant either a copolymer (of statistical type, gradient, block, alternating), or a homopolymer.
The term "monomer" as used refers to a molecule which can undergo polymerization.
The term "polymerization" as used relates to the process for transforming a monomer or a mixture of monomers into a polymer of predefined architecture (block, gradient, statistics, etc.).
The term “copolymer” means a polymer grouping together several different monomer units.
The term “statistical copolymer” is intended to mean a copolymer in which the distribution of the monomer units along the chain follows a statistical law, for example of the Bernoullien type (zero Markov order) or Markovian of the first or second order. When the repeating units are randomly distributed along the chain, the polymers were formed by a Bernouilli process and are called random copolymers. The term random copolymer is often used, even when the statistical process that prevailed during the synthesis of the copolymer is not known.
The term “gradient copolymer” is understood to mean a copolymer in which the distribution of the monomer units varies gradually along the chains.
The term “alternating copolymer” is understood to mean a copolymer comprising at least two monomeric entities which are alternately distributed along the chains.
The term “block copolymer” means a polymer comprising one or more uninterrupted blocks of each of the distinct polymer species, the
Ref: 0560-ARK89 polymer sequences being chemically different from one or other, and being linked to each other by a chemical bond (covalent, ionic, hydrogen bond, or coordination). These polymer blocks are also called polymer blocks. These blocks have a phase segregation parameter (Flory-Huggins interaction parameter) such that, if the degree of polymerization of each block is greater than a critical value, they are not miscible with each other and separate in nanoparticles. areas.
The term "miscibility" above means the ability of two or more compounds to mix completely to form a homogeneous or "pseudo-homogeneous" phase, that is to say without crystal symmetry or almost - apparent crystal at short or long distance. The miscibility of a mixture can be determined when the sum of the glass transition temperatures (Tg) of the mixture is strictly lower than the sum of the Tg of the compounds taken in isolation.
In the description, we speak of both "self-assembly" as "self-organization" or "nanostructuring" to describe the well-known phenomenon of phase separation of block copolymers, an assembly temperature also called annealing temperature.
The term “minimum thickness” of a block copolymer is understood to mean the thickness of a block copolymer film serving as a nanolithography mask, below which it is no longer possible to transfer the patterns. block copolymer film in the underlying substrate with a satisfactory final form factor. In general, for block copolymers with a high phase segregation parameter χ, this minimum thickness "e" is at least equal to half of the period L _o of the block copolymer.
The term "porous film" denotes a block copolymer film in which one or more nano-domains have been removed, leaving holes whose shapes correspond to the shapes of the nano-domains having been removed and which may be spherical, cylindrical , lamellar or helical.
The term “neutral” or “pseudo-neutral” surface is understood to mean a surface which, as a whole, does not have preferential affinity with one of the blocks of a block copolymer. It thus allows a fair or "pseudo-equitable" distribution of the blocks of the block copolymer on the surface.
Ref: 0560-ARK89 [0059] The neutralization of the surface of a substrate makes it possible to obtain such a "neutral" or "pseudo-neutral" surface.
We define the surface energy (denoted yx) of a given material "x", as being the excess energy on the surface of the material compared to that of the material taken in mass. When the material is in liquid form, its surface energy is equivalent to its surface tension.
When we talk about surface energies or more precisely the interfacial tensions of a material and of a block of a given block copolymer, these are compared to a given temperature, and more particularly to a temperature allowing the self-organization of the block copolymer.
The term “lower interface” of a (co) polymer is understood to mean the interface in contact with an underlying layer or substrate on which / which said (co) polymer is deposited. It will be noted that, throughout the rest of the description, when the polymer in question is a block copolymer to be nano-structured, intended to serve as a nanolithography mask, this lower interface is neutralized by a conventional technique, that is to say say that, as a whole, it does not have preferential affinity with one of the blocks of the block copolymer.
The term “upper interface” or “upper surface” of a (co) polymer means the interface in contact with an upper layer, called top coat and denoted TC, applied to the surface of the (co) polymer. It will be noted that, throughout the rest of the description, when the polymer in question is a block copolymer to be nanostructured, intended to serve as a nanolithography mask, the upper layer of top coat TC, like the underlying layer, does not preferably has no preferential affinity with one of the blocks of the block copolymer so that the nanodomains of the block copolymer can be oriented perpendicular to the interfaces at the time of assembly annealing.
The term "solvent orthogonal to a (co) polymer" means a solvent which is not capable of attacking or dissolving said (co) polymer.
The term “liquid polymer” or “viscous polymer” means a polymer having, at a temperature above the glass transition temperature, due to its rubbery state, an increased capacity for deformation due to the possibility given to its molecular chains to move freely, by
Ref: 0560-ARK89 opposition to "solid polymer", undeformable due to the negligible mobility of its molecular chains.
In the context of this invention, we consider any polymeric stacking system, that is to say a system comprising at least two layers of polymers stacked on top of each other. This stack can be deposited on a solid substrate of any kind (oxide, metal, semiconductor, polymer, etc.) depending on the applications for which it is intended. The different interfaces of such a system can have a "liquid / solid" or "liquid / liquid" configuration. Thus, an upper polymer layer, having a liquid or viscous state, is deposited on an underlying polymer layer which may be in a solid or liquid state, depending on the intended applications.
Figure 2 illustrates such a polymeric stack. This stack is for example deposited on a substrate 10 and comprises for example two layers of polymer 20 and 30 stacked one on the other. Depending on the intended applications, the first layer 20 may be without a solid or liquid / viscous state at the time of the deposition of the second upper layer 30, called the TC top coat. The TC top coat layer 30 is applied to the surface of the underlying layer 20, by a conventional deposition technique, for example by spin spinning, and has a liquid / viscous state.
The term "flatness of a polymeric stack" within the meaning of the invention is addressed to all the interfaces of the stack. The method according to the invention makes it possible to control the flatness of the interface between the substrate 10 and the first layer 20, and / or the flatness of the interface between the first layer 20 and the top coat layer 30, and / or the flatness of the interface between the top coat layer 30 and the air.
To avoid the appearance of a phenomenon of dewetting the layer 30 of the TC top coat just after its deposition on the underlying layer 20, and to avoid an inter-diffusion phenomenon at the interface, in particular in in the case of a liquid / liquid configuration of the interface, corresponding to the case represented in FIG. 1C, the invention advantageously consists in depositing the upper layer 30 in the form of a pre-polymer composition, denoted pre-TC, comprising one or more monomer (s) and / or dimer (s) and / or oligomer (s) and / or polymer (s). For the sake of simplification, these compounds are also called "molecules" or "entities" in the following description. This pre-TC pre-polymer composition is preferably
Ref: 0560-ARK89 applied by spin coating or "spin coating". The layer of prepolymer composition thus deposited is then subjected to a heat treatment in order to cause a crosslinking / polymerization reaction in situ, within the layer of pre-TC pre-polymer deposited and to generate the creation of a TC polymer of high molecular weight by means of the crosslinking / polymerization of the molecular chains constituting the layer of deposited prepolymer composition. During this reaction, the initial chain size increases as the reaction propagates in the layer, thus greatly limiting the solubilization of the top coat layer TC crosslinked in the underlying polymer layer 20 when the latter is in a liquid or viscous state, and further delaying the appearance of a dewetting phenomenon.
Preferably, the prepolymer composition is formulated in a solvent orthogonal to the first layer 20 of polymer already present on the substrate, and comprises at least: a monomer, dimer, oligomer or polymer chemical entity, or any mixture of these different entities, of chemical nature in all or part identical, and each comprising at least one chemical function capable of ensuring the propagation of the crosslinking / polymerization reaction under the effect of a stimulus.
The prepolymer composition can, in an alternative embodiment, be used without solvent.
According to the chemical entities monomer (s) and / or dimer (s) and / or oligomer (s) and / or polymer (s) of the pre-polymer composition, the latter may also comprise a thermally activatable catalyst . In this case, the catalyst is chosen from radical generators, or acid generators, or even basic generators.
Regarding the pre-polymer / catalyst system, it is necessary to make a compromise so that the crosslinking reaction can take place at a sufficiently low temperature, without compromising the stability of the system over time during its storage. The pre-polymer / catalyst system must therefore be thermally stable enough to be able to be stored suitably, at low temperature if necessary, without losing its crosslinking / polymerization properties. It must also be sufficiently unstable in temperature to allow a low cross-linking / polymerization reaction to be obtained.
Ref: 0560-ARK89 temperature, preferably around 100 ° C, for a few minutes. Finally, the catalyst must also have an evaporation temperature in line with the crosslinking temperature of the prepolymer composition, in order to prevent the catalyst from evaporating before having had the opportunity to react.
Preferably, in the context of the invention, at least one of the chemical entities of the prepolymer composition has at least one fluorine and / or silicon and / or germanium atom, and / or a chain aliphatic carbon of at least two carbon atoms in its chemical formula. Such entities make it possible to improve the solubility of the prepolymer composition in a solvent orthogonal to the underlying polymer layer 20 and / or to effectively modulate the surface energy of the TC top coat layer if necessary, in particular for DSA applications, and / or to facilitate the wetting of the pre-polymer composition on the underlying (co-) polymer layer 20, and / or to reinforce the resistance of the TC top coat layer with respect to screw of a subsequent plasma etching step.
Optionally, this pre-polymer composition can also comprise, in its formulation:
- a chemical entity chosen from an antioxidant, a base or a weak acid, capable of trapping said chemical entity capable of initiating the crosslinking / polymerization reaction, and / or
one or more additives making it possible to improve the wetting and / or the adhesion, and / or the uniformity of the top layer of top coat, and / or
- one or more additives making it possible to absorb one or more ranges of light radiation of different wavelength, or to modify the electrical conductivity properties of the prepolymer.
The heat treatment for causing the crosslinking / polymerization reaction consists in heating the stack in a temperature range between 0 ° C and 350 ° C, preferably between 10 ° C and 300 ° C and more preferred between 20 and 150 ° C, for a time preferably less than 15 minutes, more preferably less than 10 minutes, and more preferably less than 5 minutes. Even more advantageously, the heat treatment is less than 110 ° C. for 2 minutes of reaction.
The crosslinking / polymerization reaction can be obtained by radical route, or by ionic route or it can result from a condensation reaction
Ref: 0560-ARK89 or addition (for example, Michael addition) between two derivatives having chemical functions compatible with each other. In the case where the crosslinking / polymerization results from an addition or condensation reaction, the prepolymer composition can also comprise a multitopic / multifunctional co-reagent.
When the polymerization is radical, the monomer (s) and / or dimer (s) and / or oligomer (s) and / or polymer (s) constituting the prepolymer layer, is (are ) chosen from derivatives comprising unsaturations in their chemical structure, chosen from acrylate or methacrylate or vinyl type derivatives. More particularly, the monomer (s) and / or dimer (s) and / or oligomer (s) and / or polymer (s) constituting the pre-polymer layer, are chosen from the non-exhaustive list derivatives of acrylates or di- or tri-acrylates or multi-acrylates, methacrylate, or multi-methacrylates, or polyglycidyl or vinyl, fluoroacrylates or fluoromethacrylates, vinyl fluorides or fluorostyrene, alkyl acrylate or methacrylate, hydroxyalkyl acrylate or methacrylate, alkylsilyl acrylate or methacrylate, unsaturated esters / acids such as fumaric or maleic acids, vinyl carbamates and carbonates, allyl ethers, and thiol-ene systems.
In this case, the thermally activatable catalyst is chosen from derivatives of the organic peroxide type, or alternatively derivatives comprising a chemical function of the azo type such as azobisisobutyronitrile, or alternatively derivatives of the alkyl halide type.
When the polymerization is cationic, the monomer (s) and / or dimer (s) and / or oligomer (s) and / or polymer (s) constituting the prepolymer layer, are derivatives comprising chemical functions of epoxy / oxirane type, or vinyl ethers, cyclic ethers, thiirane, thietanes, trioxane, vinyls, lactones, lactams, carbonates, thiocarbonates, maleic anhydride. The catalyst, for its part, can be chosen from chemical derivatives making it possible to generate a thermally activated acid proton, such as ammonium salts such as ammonium triflate or trifluoroacetate, phosphoric or sulfuric or sulfonic acids, or alternatively onium salts such as iodonium or phosphonium salts, or also imidazolium salts.
Ref: 0560-ARK89 [0081] When the polymerization / crosslinking results from a condensation / addition, I the monomer (s) and / or dimer (s) and / or oligomer (s) and / or polymer (s) ) constituting the pre-polymer layer (s) can be chosen, in a non-exhaustive or limiting manner for the invention, from the combination systems between:
- a thiol or polythiol derivative and an epoxy, thiol / nitrile, thiol / vinyl derivative, or even between
- a derivative of silane or organosilane or halosilane type and a hydroxy or amino derivative, or alternatively
- a derivative of amine or polyamine type and a derivative of isocyanate, amine / epoxy, amine / aldehyde, amine / ketone type.
Finally, when the polymerization is anionic, the monomer (s) and / or dimer (s) and / or oligomer (s) and / or polymer (s) constituting the prepolymer layer are derivatives of the alkyl cyanoacrylate type, epoxides / oxiranes, acrylates, or also isocyanate or polyisocynanate derivatives.
In the particular case where the monomer (s) and / or dimer (s) and / or oligomer (s) and / or polymer (s) constituting the pre-polymer layer, are derivatives of the alkyl cyanoacrylate type, the crosslinking / polymerization reaction can be spontaneous at ambient temperature and / or be catalyzed by ambient humidity. According to a first embodiment, the monomer (s) and / or dimer (s) and / or oligomer (s) and / or polymer (s) constituting the pre-TC pre-polymer composition preferably comprise epoxy / oxirane functions, reactive with respect to temperature , in the presence of a reaction catalyst making it possible to generate an acid and / or a co-reagent capable of generating a reagent making it possible to carry out an addition reaction on the epoxy functions.
In this case, the monomeric and / or oligomeric and / or polymeric entities of the composition can for example be chosen from copolymers based on acrylate chemistry, having an architecture of monomers, such as a random copolymer or gradient of glycidylmethacrylate-co-trifluoroethylemethacrylate-cohydroxyethylemethacrylate or glycidylmethacrylate-cotrifluoroethylemethacrylate-co-butylmethacrylate.
According to this first embodiment of the invention, the catalyst is chosen from at least one of the following compounds: amines or polyamines, such as diethylene triamine (DTA), isophorone diamine (IPD), 4,4'- diaminodiphenylsulfone
Ref: 0560-ARK89 (DDS), hexamethylene diamine (HMDA), dicyandiamide (cyanoguanidine), or ammonium salts, such as ammonium triflate or ammonium trifluoroacetate, or ascorbic acid and its derivatives, chosen from sodium or magnesium ascorbate or sodium, magnesium or ammonium ascorbylphosphate, as well as the various possible isomers (diastereoisomers, enantiomers) of ascorbic acid; uric acid; phenol, polyphenols and phenolic derivatives such as hydroquinone, resorcinol, 2,4-pentanedione, malonaldéhyde (propanedial), tartronaldéhyde (2-hydroxypropanedial), furanone and more generally reductones.
The co-reagent, for its part, is chosen from at least one of the following reagents: thiols or polythiols such as pentaerythritoltetrakis (3mercaptopropionate); imidazoles and imidazolium derivatives; acid anhydrides, such as, for example, succinic anhydride or even maleic anhydride; hydrazines.
Most known thermosetting systems consist of a mixture of two compounds which react with each other at the desired temperature, the mixing being carried out just before use due to the high reactivity of the system. However, for certain applications, such as those dedicated to electronics, in which it is necessary to precisely dose the constituents of the mixture each time they are deposited on an underlying layer, the fact of mixing the two compounds just before job appears complicated to implement to achieve the top coat layer of a polymeric stack. Consequently, the constituent compounds of the prepolymer composition, that is to say the monomer (s) and / or dimer (s) and / or oligomer (s) and / or polymer (s) and the catalyst must be able to be mixed in solution. The prepolymer composition, the crosslinking reaction of which is activated by a rise in temperature, must also be sufficiently stable over time to avoid any problem of degradation of the chemical properties.
The solvent for the prepolymer layer is chosen so as to be entirely "orthogonal" to the polymer system of the underlying layer in order to avoid a possible re-dissolution of this polymer in the solvent for the prepolymer layer during the deposition step (by spin-coating for example). The solvents of each respective layer will therefore be very dependent on the chemical nature of the
Ref: 0560-ARK89 polymer material already deposited on the substrate. Thus, if the polymer already deposited is not very polar / protic, its solvent being selected from solvents that are not very polar and / or not very protic, the pre-polymer layer can therefore be dissolved and deposited on the first polymer layer from solvents that are rather polar. and / or protics. Conversely, if the polymer already deposited is rather polar / protic, the solvents of the pre-polymer layer may be chosen from solvents that are not very polar and / or not very protic. According to a preferred embodiment of the invention, but without this being restrictive in view of what has been explained above, the pre-polymer layer is deposited from solvents / mixtures of polar and / or protic solvents. More precisely, the polarity / proticity properties of the different solvents are described according to the nomenclature of Hansen solubility parameters (Hansen, Charles M. (2007) Hansen solubility parameters: a user's handbook, CRC Press, ISBN 0-8493- 7248-8), where the designation "ô _d " represents the forces of dispersion between solvent / solute molecules, "δ _ρ " represents the energy of the dipole forces between molecules, and "ô _h " represents the energy of the forces of possible hydrogen bonds between molecules, the values of which are tabulated at 25 ° C. In the context of the invention, by “polar and / or protic” is defined a solvent / molecule or mixture of solvents having a polarity parameter such as δ _ρ > 10 MPa ^1/2 and / or a hydrogen bonding parameter such that oh ^ 10 MPa ^1/2 . In the same way, a solvent / molecule or mixture of solvents is defined by “little polar and / or protic” when the Hansen solubility parameters are such that δρ <10 MPa ^1/2 and / or ôh <10 MPa ^{1 / 2} , and preferably δρ <8 MPa ^1/2 and / or a hydrogen bonding parameter such as ô _h ^ 9 MPa ^1/2 .
According to a preferred but non-restrictive embodiment of the invention, the solvent for the prepolymer composition can, for example, be chosen from polar prototic and / or polar aprotic solvents such as, for example, alcohols such as methanol, ethanol, isopropanol, 1-methoxy-2-propanol, hexafluoroisopropanol; or water; dimethyl sulfoxide (DMSO); dimethylformamide; acetonitrile; diols such as ethylene glycol or propylene glycol; dimethylacetamide, gammabutyrolactone, ethyl lactate or a mixture of these.
More generally, in the context of one of the preferred but not exhaustive embodiments of the invention, the various constituents of the layer
Ref: 0560-ARK89 pre-polymer are soluble and stable in solvents whose Hansen solubility parameters are such that δ _ρ > 10 MPa ^1/2 and / or ôh ^ 10 MPa ^1/2 as defined above, and with the dispersion parameter ôd <25 MPa ^1/2 .
Preferably, the temperature T _r of crosslinking / polymerization is lower than the glass transition temperature Tg of the underlying polymer layer 20 in order to guarantee the absence of a dewetting phenomenon.
However, in certain cases, the crosslinking temperature T _r may be higher than the glass transition temperature Tg of the underlying polymer layer 20. In such a situation, the stacking of the polymer layer 20 and of the layer of prepolymer composition 30 is found in a liquid / liquid configuration favorable to dewetting and inter-diffusion phenomena. A competition then arises between the crosslinking / polymerization reaction of the prepolymer composition to form the crosslinked / polymerized TC top coat layer and the appearance of a phenomenon of dewetting of the layer of deposited prepolymer composition. In order to guarantee the complete absence of deformation of the stack, due to the dewetting of the layer of prepolymer composition before its complete crosslinking, it is therefore necessary to ensure, in this case, that the crosslinking reaction is significantly faster as the hydrodynamic processes leading to dewetting.
For this, the catalyst is advantageously chosen as a function of its catalytic activity but also of the activation temperature at which it makes it possible to activate the crosslinking. The temperature T _r of the crosslinking reaction can indeed be chosen so as to obtain a speed of crosslinking faster than the dewetting kinetics, without however degrading the stack.
For this purpose, a so-called “flash” crosslinking, lasting from a few seconds to a few tens of seconds, for example between 2 and 50 seconds, can advantageously be envisaged in order to ensure the absence of dewetting. Amines or polyamines, such as diethylene triamine (DTA), isophorone diamine (IPD), 4,4'-diaminodiphenylsulfone (DDS), hexamethylene diamine (HMDA), dicyandiamide (cyanoguanidine), or the salts of ammonium, such as ammonium triflate or ammonium trifluoroacetate, or ascorbic acid and its derivatives, chosen from sodium or magnesium ascorbate or sodium, magnesium or ammonium ascorbyl phosphate , as well as
Ref: 0560-ARK89 different isomers (diastereoisomers, enantiomers) possible of ascorbic acid; uric acid; phenol, polyphenols and phenolic derivatives such as hydroquinone, resorcinol, 2,4-pentanedione, malonaldéhyde (propanedial), tartronaldéhyde (2-hydroxypropanedial), furanone and more generally reductones appear as catalysts of choice because not only do they allow a rapid crosslinking / polymerization reaction, with kinetics of less than or equal to 3 minutes, but also they allow the crosslinking / polymerization temperature of the polymer to be lowered in a more affordable temperature range, typically less than 300 ° C, and preferably less than 250 ° C, and more preferably less than 150 ° C.
If the crosslinking / polymerization reaction results from addition / condensation reactions, a co-reagent can be chosen from thiols or polythiols such as pentaerythritol-tetrakis (3mercaptopropionate); imidazoles and imidazolium derivatives; acid anhydrides, such as, for example, succinic anhydride or even maleic anhydride; hydrazines. Such a co-reagent also makes it possible to obtain a rapid crosslinking / polymerization reaction, with kinetics of less than or equal to 3 minutes, at a temperature below 300 ° C. and which can preferably be below 150 ° C.
If the crosslinking reaction takes place according to a radical reaction, the catalyst can also be chosen from chemical derivatives of organic peroxide type, or alternatively derivatives comprising a chemical function of azo type such as azobisisobutyronitrile, or alternatively alkyl halide derivatives. In this case too, the catalyst makes it possible to obtain a rapid crosslinking / polymerization reaction, with kinetics of less than or equal to 3 minutes, at a temperature of less than 300 ° C, and preferably less than 250 ° C, and more preferably less than 150 ° C.
Preferably, the catalyst or the reagent / co-reactant (in the case of crosslinking / polymerization resulting from addition / condensation reactions) is introduced into the prepolymer composition with a mass content less than or equal to 80% the total dry weight of the composition.
In a second embodiment, the preTC pre-polymer composition comprises one or more multifunctional acrylic monomer (s), such as cyanoacrylate derivatives. These cyanoacrylate derivatives are chosen from one to
Ref: 0560-ARK89 minus the following compounds: alkyl cyanoacrylate, linear or branched, such as methyl cyanoacrylate, ethyl cyanoacrylate, butyl cyanoacrylate, or octyl cyanoacrylate, neopentyl cyanoacrylate, cyanoacrylate d octadecyl, or alternatively 2ethylphenyl cyanoacrylate, or alternatively alkylalkoxy cyanoacrylate, such as 2-ethoxylethyl cyanoacrylate, or tetrahydrofurfuryl cyanoacrylate, or trifluroropropyl cyanoacrylate, or perfluororo alkyl cyanoacrylate.
In this case, the presence of a catalyst within the prepolymer composition is not necessary, since the polymerization / crosslinking reaction of these derivatives is spontaneous at room temperature (that is to say at a temperature between 15 ° C and 30 ° C). To allow a spontaneous reaction to be obtained, the crosslinking temperature T _r must be lower than the glass transition temperature Tg of the underlying polymer layer. In addition, the highest glass transition temperature of the first underlying polymer layer must itself be greater than room temperature, that is to say greater than 25 ° C.
According to this embodiment, the reactive compound (of cyanoacrylate type) is present alone in its phase, or in mixture with another cyanoacrylate derivative carrying different substituents, and in the initial state of monomer or in the form of a mixture of monomers having the same chemical functions ensuring crosslinking. The crosslinking reaction can then be simply induced by the humidity of the ambient atmosphere, according to the mechanism represented by reaction (I) below.
Naked
CH ₂ -C — CH ₂ -C ') —Q j ₌₌ Q
CH ₃ -0 CH3-O
A dispensation of water or alcohol on the layer of prepolymer composition can also be carried out in order to accelerate the crosslinking reaction.
In this case, the crosslinking reaction then takes place at very moderate temperature, typically between 5 ° C and 100 ° C and preferably less than or equal to 30 ° C. In addition, this crosslinking reaction has the advantage of being rapid,
Ref: 0560-ARK89 typically from a few tens of seconds to a few minutes and in any case less than 5 minutes.
The cyanoacrylate type monomers can be stored without degradation for a correct period of time, from a few weeks to a few months, subject to a few basic precautions, such as for example storage in a dry / controlled atmosphere, at low temperature, etc. .
The monomer or mixture of monomers can be dissolved in a solvent orthogonal to the underlying polymer layer 20 which can, for example, be chosen from polar protic and / or aprotic polar solvents mentioned above such as, for example, alcohols such as methanol, ethanol, isopropanol, 1-methoxy-2-propanol, hexafluoroisopropanol; or water; dimethyl sulfoxide (DMSO); dimethylformamide; acetonitrile; diols such as ethylene glycol or propylene glycol; dimethylacetamide, gammabutyrolactone, ethyl lactate or a mixture of these. Preferably, in the context of this second embodiment, the solvent is aprotic polar.
In some cases, when the monomer or mixture of monomers has a low viscosity at room temperature, for example less than 50 centipoise, then it may be deposited pure on the underlying layer, that is to say without solvent.
From a practical point of view, the crosslinking / polymerization temperature can be obtained for example via a simple heating plate, without this single example being limiting for the present invention. Thus, in another example, it is possible to heat the layer of prepolymer composition by means of an infrared laser or of a broadband spectrum lamp whose wavelengths are located in the infrared red, such as 800 to 1500nm, for example.
The invention as described above can be applied to any type of polymeric stack. Among the diverse and varied applications of such stacks, the applicant has more particularly been interested in nanolithography by directed self-assembly, or DSA. However, the invention is not limited to this example which is given by way of illustration and is in no way limiting. In fact, in the context of such an application, the top coat TC top layer must also meet other additional requirements, in particular to allow
Ref: 0560-ARK89 nano-domains of the underlying copolymer to orient themselves perpendicular to the interfaces.
[0109] Figure 3 illustrates such a polymeric stack dedicated to an application in the field of organic electronics. This stack is deposited on the surface of a substrate 10. The surface of the substrate is previously neutralized or pseudo-neutralized by a conventional technique. For this, the substrate 10 may or may not have patterns, said patterns being pre-drawn by a step or a sequence of lithography steps of any kind prior to the step of depositing the first layer (20) of block copolymer. (BCP), said patterns being intended to guide the organization of said block copolymer (BCP) by a technique called chemistry-epitaxy or graphoepitaxy, or a combination of these two techniques, to obtain a neutralized surface. A particular example consists in grafting a layer 11 of a random copolymer comprising a judiciously chosen ratio of the same monomers as those of the block copolymer BCP 20 deposited above. Layer 11 of the random copolymer makes it possible to balance the initial affinity of the substrate for the BCP 20 block copolymer. The grafting reaction can be obtained by any thermal, photochemical or even redox method, for example. Then, a TC 30 top coat layer is deposited on the layer of BCP block copolymer 20. This TC layer 30 must have no preferential affinity with respect to the blocks of the block copolymer 20 so that the nano-domains 21, 22 which are created during annealing at the assembly temperature Tass, are oriented perpendicular to the interfaces, as illustrated in FIG. 3. The block copolymer is necessarily liquid / viscous at the assembly temperature, in order to to be able to nano-structure. The top coat layer TC 30 is also deposited on the block copolymer 20 in a liquid / viscous state. The interface between the two polymer layers is therefore in a liquid / liquid configuration suitable for the phenomena of inter-diffusion and dewetting.
As regards the layer 20 of nano-structured block copolymer, also denoted BCP, it comprises “n” blocks, n being any integer greater than or equal to 2. The BCP block copolymer is more particularly defined by the following general formula:
A-b-B-b-b-C-D-B -....- b-Z
Ref: 0560-ARK89 where A, B, C, D, ..., Z, are as many blocks "i" ... "j" representing either pure chemical entities, that is to say that each block is a set of monomers of identical chemical nature, polymerized together, that is to say a set of comonomers copolymerized together, in the form, in whole or in part, of block copolymer or statistical or random or with gradient or alternating.
Each of the blocks "i" ... "j" of the BCP block copolymer to be nanostructured can therefore potentially be written in the form: i = aj-co-bi-co -...- co-Zj, with i # ... / j, in whole or in part.
The volume fraction of each entity aj ... Zj can range from 1 to 99%, in units of monomer, in each of the blocks i ... j of the BCP block copolymer.
The volume fraction of each of the blocks i ... j can range from 5 to 95% of the BCP block copolymer.
The volume fraction is defined as the volume of an entity relative to that of a block, or the volume of a block relative to that of the block copolymer.
The volume fraction of each entity of a block of a copolymer, or of each block of a block copolymer, is measured as described below. Within a copolymer in which at least one of the entities, or one of the blocks if it is a block copolymer, comprises several co-monomers, it is possible to measure, by NMR of the proton, the molar fraction of each monomer in the entire copolymer, then go back to the mass fraction using the molar mass of each monomer unit. To obtain the mass fractions of each entity in a block, or each block of a copolymer, it suffices to add the mass fractions of the co-monomers constituting the entity or of the block. The volume fraction of each entity or block can then be determined from the mass fraction of each entity or block and the density of the polymer forming the entity or block. However, it is not always possible to obtain the density of polymers whose monomers are co-polymerized. In this case, the volume fraction of an entity or block is determined from its mass fraction and the density of the majority compound by mass of the entity or block.
The molecular weight of the BCP block copolymer can range from 1000 to 500,000 g.mol · ¹ .
Ref: 0560-ARX89 [0117] The BCP block copolymer can have any type of architecture: linear, star (tri- or multi-arm), grafted, dendritic, comb.
Each of the blocks i, ... j of a block copolymer has a surface energy denoted γ, ... yj, which is specific to it and which is a function of its chemical constituents, that is to say -to say of the chemical nature of the monomers or co-monomers which compose it. Likewise, each of the materials making up a substrate have their own surface energy value.
Each of the blocks i, ... j of the block copolymer also has an interaction parameter of the Flory-Huggins type, noted: χ _ίχ , when it interacts with a given material "x", which can be a gas, a liquid, a solid surface, or another polymer phase for example, and an inter-facial energy denoted “γ, _χ ”, with Yix = Yi- (Y _x cos 0 _ix ), where 0 _ix is l contact angle between materials i and x. The interaction parameter between two blocks i and j of the block copolymer is therefore noted χ ^.
There is a relationship linking γ, and the Hildebrand solubility parameter δ, of a given material i, as described in the document Jia & al., Journal of Macromolecular Science, B, 2011, 50, 1042. In fact, the Flory Huggins interaction parameter between two given materials i and x is indirectly linked to the surface energies γ, and γ _χ specific to materials, we can therefore either speak in terms of surface energies, or in interaction parameter terms to describe the physical phenomenon appearing at the interface of materials.
When we talk about surface energies of a material and those of a given BCP block copolymer, we mean that we compare the surface energies at a given temperature, and this temperature is the one (or at least part of the temperature range) allowing the self-organization of the BCP.
In the same manner as described above for any stack of polymers, the upper layer 30, which is deposited on layer 20 of BCP block copolymer, is in the form of a prepolymer composition, denoted pre-TC , and comprises one or more monomer (s) and / or dimer (s) and / or oligomer (s) and / or polymer (s). Thanks to the thermal activation of the layer of prepolymer composition thus deposited, a crosslinking / polymerization reaction of the molecular chains constituting the layer of prepolymer takes place in situ, within the layer of prepolymer. pre-TC deposited, and generates the creation of a TC polymer of high molecular mass. A single chain is created
Ref: 0560-ARK89 of an extremely immiscible polymer with the underlying BCP block copolymer, thus greatly limiting the solubilization of the TC top coat layer 30 in the underlying BCP block copolymer layer 20 and delaying all the more the appearance of a dewetting phenomenon. Thus, the heat-crosslinking / thermo-polymerization of the layer of TC top coat not only avoids the problems of interdiffusion and dewetting of the layer of TC top coat on the underlying BCP 20 block copolymer. , but also to stabilize the block copolymer layer 20 so that it does not wilt from its substrate 10. The crosslinking / polymerization of the top coat layer TC 30 therefore makes it possible to obtain a stack, the surface of which is perfectly flat. , with perfectly clear substrate / block copolymer (substrate / BCP) and block / top coat copolymer (BCP / TC) interfaces.
Such a TC top coat layer thus crosslinked / polymerized has a surface energy, at the temperature allowing the self-assembly of the underlying BCP 20 block copolymer, of between 10 and 50 mN / m, preferably between 20 and 45 mN / m and more preferably between 25 and 40 mN / m.
However, the thermo-crosslinking / thermo-polymerization reaction involves chemical species, such as carbanions, carbocations or radicals, which are more reactive than a simple non-crosslinkable top coat layer. It is therefore possible, in certain cases, that these chemical species can diffuse and possibly degrade the BCP 20 block copolymer. Such diffusion is however very limited, over a thickness of a few nanometers at most and in all cases less than 10 nm. , due to the immiscible nature of the TC 30 top coat layers and of BCP 20 block copolymer. Due to such diffusion, the effective thickness of the block copolymer layer may then be reduced. To compensate for this possible diffusion, the BCP 20 block copolymer can be deposited on a greater thickness (e + E), for example at least 1.5 times the minimum thickness e of the block copolymer. In this case, after nanostructuring and when removing the top coat layer TC, the excess thickness E of block copolymer is also removed in order to keep only the lower part, of minimum thickness e, of the block copolymer .
Anyway, if it takes place, diffusion being limited to a thickness of a few nanometers at most, it forms an intermediate layer comprising an intimate mixture of the constituents of the BCP 20 block copolymer and
Ref: 0560-ARK89 the TC 30 top coat layer. This intermediate layer then has an intermediate surface energy, between that of the pure TC 30 top coat and that of the average surface energy of the blocks of the BCP 20 block copolymer. , so that it has no particular affinity with one of the blocks of the BCP block copolymer and therefore makes it possible to orient the nano-domains of the underlying BCP block copolymer 20 perpendicular to the interfaces.
Advantageously, the deposition of a layer of prepolymer followed by its crosslinking / polymerization, makes it possible to overcome the problems associated with the need to synthesize a top coat material of high molecular weight. It suffices to synthesize monomers, dimers, oligomers or polymers whose molecular weights are much more reasonable, typically of the order of an order of magnitude less, thus limiting the difficulties and the operating conditions specific to the stage of chemical synthesis. Crosslinking of the prepolymer composition then allows these high molecular weights to be generated in situ.
The fact of depositing a prepolymer composition, comprising monomers, dimers, oligomers or polymers of much lower molecular weight than a non-crosslinked top coat material, also makes it possible to widen the possible range of solvents for the TC top coat material, these solvents having to be orthogonal to the BCP block copolymer.
Most known thermosetting systems consist of a mixture of two compounds which react with each other at the desired temperature, the mixing being carried out just before use due to the high reactivity of the system. However, the fact of mixing the two compounds just before use appears to be complicated to implement in order to produce a top coat layer of a polymeric stack dedicated to nano-lithography by directed self-assembly. Indeed, in such a case, it would be necessary to be able to precisely dose the constituents of the mixture, each time they are deposited on an underlying layer of BCP block copolymer, in order to be able to guarantee that the top coat layer Crosslinked CT is neutral vis-à-vis the blocks of the BCP block copolymer and thus ensure that the nanodomains of the block copolymer can orient themselves perpendicularly to the interfaces at the time of annealing at assembly temperature. However, when a mixture of two chemical compounds is involved, the neutrality of the crosslinked TC top coat layer may depend on the ratio between the two compounds.
Ref: 0560-ARK89 [0129] Consequently, the constituent components of the pre-polymer composition must be able to be mixed in solution. The prepolymer composition, the crosslinking reaction of which is activated by a rise in temperature, must also be sufficiently stable over time to avoid any problem of degradation of the chemical properties.
In the same manner as described above and according to the first embodiment, the prepolymer composition comprises a mixture of monomer (s) and / or dimer (s) and / or oligomer (s) and / or polymer (s), preferably having epoxy / oxirane functions, and a reaction catalyst and / or a co-reactant, in solution.
According to the first embodiment of the invention, the monomers / oligomers / polymers of the composition can for example be chosen from copolymers based on acrylate chemistry, having an architecture of monomers, such as a random or gradient copolymer glycidylmethacrylate-cotrifluoroethylemethacrylate-co-hydroxyethylemethacrylate or glycidylmethacrylate-co-trifluoroethylemethacrylate-co-butylmethacrylate.
The catalyst is chosen from at least one of the following compounds: amines or polyamines, such as diethylene triamine (DTA), isophorone diamine (IPD), 4,4'-diaminodiphenylsulfone (DDS), hexamethylene diamine (HMDA), dicyandiamide (cyanoguanidine), or ammonium salts, such as ammonium triflate or ammonium trifluoroacetate, or ascorbic acid and its derivatives, chosen from ascorbate sodium or magnesium or sodium, magnesium or ammonium ascorbylphosphate, as well as the various possible isomers (diastereoisomers, enantiomers) of ascorbic acid; uric acid; phenol, polyphenols and phenolic derivatives such as hydroquinone, resorcinol, 2,4-pentanedione, malonaldéhyde (propanedial), tartronaldéhyde (2-hydroxypropanedial), furanone and more generally reductones.
The co-reagent, used when the crosslinking / polymerization reaction results from addition / condensation reactions, is chosen from thiols or polythiols such as pentaerythritol-tetrakis (3mercaptopropionate); imidazoles and imidazolium derivatives; acid anhydrides, such as, for example, succinic anhydride or even maleic anhydride; hydrazines.
Ref: 0560-ARK89 [0134] In this case, the total surface energy of the cross-linked / polymerized TC top coat material will be modulated by the chemical nature of the group which adds up on the reactive function. Thus, if we consider the addition of tri-phenylamine (TPA) on glycidylmethacrylate (GMA), it will be necessary to take into account the couple GMA / TPA rather than GMA alone for the calculation of the surface energy.
The solvent for the prepolymer composition can, for example, be chosen from polar protic solvents such as, for example, alcohols such as methanol, ethanol, isopropanol, 1-methoxy-2-propanol, hexafluoroisopropanol; or water; dimethyl sulfoxide (DMSO); dimethylformamide; acetonitrile; diols such as ethylene glycol or propylene glycol; dimethylacetamide, gammabutyrolactone, ethyl lactate or a mixture thereof.
It should also be ensured that the solvent of the prepolymer composition is orthogonal to the BCP 20 block copolymer on which the prepolymer composition is deposited in the form of a layer, so as not to re-dissolve the block copolymer at the time of filing.
In order to obtain a layer 30 of crosslinked TC top coat which is neutral with respect to the underlying block copolymer 20, that is to say which does not have any particular affinity for of each of the blocks of the block copolymer, the pre-TC pre-polymer composition preferably comprises molecules (monomer (s), dimer (s), oligomer (s) or polymer (s)) which have the same chemical functions epoxy / oxirane which ensure crosslinking, but different chemical groups in order to be able to modulate the overall surface energy of the material and to obtain a crosslinked TC top coat layer which is neutral with respect to the blocks of underlying block copolymer. An example of this type of material can be obtained for example through the crosslinking of a random polymer from three co-monomers, such as a poly (gycidyl-cotrifluoroethylemethacrylate-co-hydroxyehtylemethacrylate), where the glycidyl units ensure intermolecular crosslinking chains, and where the ratio trifluoroethyl methacrylate (unit having a low surface energy due to the presence of fluorine atoms) and hydroxyethyl methacrylate (unit having a high surface energy due to the presence of the hydroxy chemical function, and favoring the solubilization of the material in polar protic solvents) makes it possible to modulate the desired surface energy.
Ref: 0560-ARK89 [0138] Preferably, the crosslinking temperature T _r of the layer of pre-TC pre-polymer composition is much lower than the glass transition temperature of the underlying 20 BCP block copolymer, itself lower than the assembly temperature T _ass of the BCP block copolymer enabling it to be nanostructured in nano-domains, for a reaction time of a few seconds to a few minutes maximum, preferably less than 15 minutes, more preferably less than 10 minutes, and advantageously less than 5 minutes, this in order to guarantee the highest possible conversion efficiency of the layer of prepolymer composition into crosslinked / polymerized polymer layer. Typically, but without limitation for the invention, preferably the crosslinking temperature is between 0 ° C and 350 ° C, more preferably between 10 ° C and 300 ° C, and advantageously between 20 ° C and 150 ° C. Preferably, the highest glass transition temperature of the BCP block copolymer is between 20 ° C and 350 ° C, and more preferably between 30 ° C and 150 ° C. Preferably the assembly temperature of the BCP block copolymer is greater than 50 ° C and more preferably greater than 100 ° C.
However, if the crosslinking temperature T _r of the pre-TC pre-polymer composition layer is higher than the glass transition temperature Tg of the underlying BCP block copolymer, in this case, the crosslinking / polymerization must be "flash" to ensure total crosslinking of the layer and the absence of any dewetting phenomenon. For this, the catalysts or co-reactants of the polyamine type, ammonium salts, or ascorbic acid and its derivatives or phenol and the phenolic derivatives mentioned above, make it possible to obtain crosslinks in a few seconds.
Finally, in this case, the crosslinking temperature Tr of the layer of pre-TC pre-polymer composition can be either lower or higher than the assembly temperature Tass of the underlying BCP block copolymer. When it is higher than the assembly temperature, taking into account the reversibility of the order / disorder or order / order transitions, assembly annealing subsequent to the crosslinking of the TC top coat layer makes it possible to reassemble the underlying BCP block copolymer which may have been disordered during the crosslinking step.
Ref: 0560-ARK89 [0141] According to the second embodiment, the pre-polymer preTC composition comprises one or more multifunctional acrylic monomer (s), such as cyanoacrylate derivatives. In this case, the presence of a catalyst within the prepolymer composition is not necessary, since the polymerization / crosslinking reaction is spontaneous at room temperature, and catalyzed by ambient humidity. According to this embodiment, the underlying block copolymer must be solid at the crosslinking / polymerization temperature of the layer of prepolymer composition. For this, the crosslinking temperature T _r of the layer of prepolymer composition must be lower than the highest glass transition temperature Tg of the BCP block copolymer (T _r <Tg ^BCP ) and the block copolymer must have at least one block of which at least 40% of the composition has a glass transition temperature above room temperature, that is to say above 25 ° C. In this case, the reactive compound, of cyanoacrylate type, is present alone in its phase and in the initial state of monomer or in the form of a mixture of monomers each having the same chemical functions ensuring crosslinking / polymerization, but each of the monomers carrying different chemical groups (such as different ester groups) in order to ensure the modulation of the overall surface energy of the material and to obtain a cross-linked TC top coat layer neutral with respect to the BCP block copolymer under -jacent. The crosslinking / polymerization reaction can then be simply induced by the humidity of the ambient atmosphere, or else a dispensation of water or alcohol on the layer of prepolymer composition can be carried out in order to accelerate the reaction of crosslinking.
In this case, the crosslinking / polymerization reaction then takes place at very moderate temperature, typically between 15 ° C and 100 ° C and preferably less than or equal to 40 ° C. In addition, this crosslinking reaction has the advantage of being rapid, typically from a few tens of seconds to a few minutes and in all cases less than 5 minutes.
In order to further limit a possible phenomenon of dewetting of the TC top coat layer 30, the rigidity (measured for example by estimating the Young's modulus of the TC top coat once crosslinked or polymerized) and the glass transition temperature of the top coat layer can be reinforced by the introduction, into the pre-TC pre-polymer composition, of rigid co-monomers
Ref: 0560-ARK89 chosen from derivatives comprising either an aromatic ring (s) in their structure, or mono or multi-cyclic aliphatic structures, and having a suitable chemical function (s) (s) to the intended crosslinking / polymerization reaction. More particularly, these rigid co-monomers are chosen from norbornene derivatives, isobornyl acrylate or methacrylate, styrenic, anthracene derivatives, adamantyl acrylate or methacrylate.
However, in the context of nano-lithography applications by directed self-assembly, it is necessary to ensure that the TC top coat once formed, does not correspond to a porous or multiphase network, in order to avoid possible problems of non-uniformity / demixing of the TC top coat for the underlying BCP block copolymer. To this end, the pre-TC pre-polymer composition can comprise plasticizers and / or wetting agents as additives if necessary. In the context of other applications, such as the manufacture of biocompatible membranes or implants for example, it may on the contrary be advantageous for the TC top coat, once formed, to correspond to such a porous or multiphasic network.
In order to be able to manufacture a nano-lithography mask for example, once the TC top coat layer has been crosslinked, the stack obtained, having a clear BCP / TC interface and a perfectly flat surface, is subjected to annealing at a assembly temperature Tass, for a determined period, preferably less than 10 minutes and more preferably less than 5 minutes, in order to cause the nanostructuring of the block copolymer. The nano-domains 21, 22 which form are then oriented perpendicular to the neutralized interfaces of the BCP block copolymer.
Then, once the block copolymer has been organized, the TC top coat layer can be removed.
One way of removing the crosslinked TC top coat layer is to use dry etching, such as plasma for example with an appropriate gas chemistry, such as a majority oxygen base in a mixture with a rather inert gas. such as He, Ar, N ₂ for example. Such dry etching is all the more advantageous and easy to carry out if the underlying BCP 20 block copolymer contains, for example, silicon in one of its blocks, then acting as an etching stop layer.
Such a dry etching can also be advantageous in the case where the underlying BCP block copolymer has been deposited with an extra thickness E and where
Ref: 0560-ARK89 not only the top coat TC must be removed but also the extra thickness E of block copolymer. In this case, the chemistry of the gases making up the plasma must be adjusted as a function of the materials to be removed so as not to have a specific selectivity for a block of the BCP block copolymer. The top coat layer TC and the extra thickness E of the BCP block copolymer can then be removed simultaneously or successively, in the same etching frame, by plasma etching by adjusting the gas chemistry according to the constituents of each of the layers to be removed. .
In the same way, at least one of the blocks 21, 22 of the BCP block copolymer 20, is removed so as to form a porous film capable of serving as a mask for nano-lithography. This removal of the block (s) can also be carried out in the same dry etching frame, successively with the removal of the top coat layer TC and of the possible additional thickness E of block copolymer.
It is also possible to select regions of the prepolymer layer intended to be crosslinked and other regions intended to remain in the state of an amorphous layer of prepolymer. In this case, the substrate / BCP / pre-TC stack is subjected to a high temperature annealing by means of a local thermal source. This local heat source can be an infrared laser for example, or a broadband infrared spectrum lamp through a lithography mask, for which a set of wavelengths is used rather than a restricted range as in the case of radiation of the laser type, or via a mechanical means such as a heating tip of an atomic force microscope, or also a “roll-to-roll” type process, in which a nano-structured heated roller is contacted with the surface of the layer of prepolymer composition by printing. This localized heat treatment of certain zones of the pre-polymer layer must allow crosslinking / polymerization of the “flash” type.
In the context of the application of the method according to the invention to nanolithography by directed self-assembly, the crosslinked / polymerized areas of top coat have a neutral affinity with respect to the underlying block copolymer, while the non-crosslinked / polymerized top coat zones may have a preferential affinity with at least one of the blocks of the underlying block copolymer. It then becomes possible to define areas of interest on the same stack, where the preTC pre-polymer layer can be crosslinked / polymerized, by thermo
Ref: 0560-ARK89 crosslinking, and other areas where the preTC pre-polymer layer will remain in the uncrosslinked / polymerized amorphous state. In this case, the patterns of the underlying BCP block copolymer will be perpendicular to the interfaces in areas located opposite the areas of the neutral top coat having been heated and crosslinked, whereas they will on the contrary be oriented parallel to the interfaces in the others. zones, located opposite unheated and therefore non-crosslinked zones. The patterns oriented parallel to the interfaces cannot then be transferred into the underlying substrate during subsequent etching steps.
To do this, the following method can simply be carried out. The pre-TC pre-polymer layer is deposited, then areas of interest of this layer are heated locally, by means of an infrared laser for example. The layer obtained is then rinsed in the solvent used for its deposition, for example, the solvent itself being orthogonal to the block copolymer. This rinsing removes the areas of prepolymer composition that have not been heated and therefore have not crosslinked. Optionally, another pre-polymer material, which is not neutral with respect to the underlying block copolymer, can be deposited in the areas not previously heat treated and having been rinsed, therefore devoid of a top coat layer, then said non-neutral pre-polymer material is subjected to a localized heat treatment in order to crosslink / polymerize it at predefined locations. The stack is then annealed at assembly temperature so that the block copolymer is structured. In this case, the nano-domains located opposite the crosslinked / polymerized neutral zones of the TC top coat layer are oriented perpendicular to the interfaces, while the nano-domains opposite the zones lacking neutral and crosslinked / polymerized top coat are oriented parallel to the interfaces.
Ref: 0560-ARK89

权利要求:
Claims (46)
[1" id="c-fr-0001]
1. Method for controlling the flatness of a polymeric stack, said stack comprising at least a first and a second layer of (co-) polymer (20, 30) stacked one on the other, the first layer (co -) underlying polymer (20) which has not undergone any prior treatment allowing its crosslinking, at least one of the (co-) polymer layers being initially in a liquid or viscous state, said process being characterized in that the layer upper (30), called top coat (TC) is deposited on the first layer (20) in the form of a pre-polymer composition (pre-TC), comprising at least one monomer (s) and / or dimer (s) ) and / or oligomer (s) and / or polymer (s) in solution, and in that it is then subjected to a heat treatment capable of causing a reaction of crosslinking / polymerization of the molecular chains within said layer (30 , TC).
[2" id="c-fr-0002]
2. Method according to claim 1, characterized in that the heat treatment consists in heating the stack in a temperature range between 0 ° C and 350 ° C, preferably between 10 ° C and 300 ° C and more preferred between 20 and 150 ° C, for a time preferably less than 15 minutes, more preferably less than 10 minutes, and more preferably less than 5 minutes.
[3" id="c-fr-0003]
3. Method according to claim 1 or 2, characterized in that the prepolymer composition (pre-TC) is a composition formulated in a solvent, or used without solvent, and which comprises at least one chemical entity monomer, dimer, oligomer or polymer , or any mixture of these different entities, of chemical nature in whole or in part identical, and each comprising at least one chemical function capable of ensuring the crosslinking / polymerization reaction under the effect of a thermal stimulus.
[4" id="c-fr-0004]
4. Method according to one of claims 1 to 3, characterized in that the pre-polymer composition (pre-TC) further comprises a thermally activatable catalyst chosen from radical generators, or acid generators, or alternatively basic generators.
[5" id="c-fr-0005]
5. Method according to one of claims 1 to 4, characterized in that at least one of the chemical entities of the prepolymer composition has at least one fluorine and / or silicon and / or germanium atom, and / or an aliphatic carbon chain of at least two carbon atoms in its chemical formula.
Ref: 0560-ARK89
[6" id="c-fr-0006]
6. Method according to one of claims 1 or 5, characterized in that said pre-polymer composition (pre-TC) further comprises in its formulation:
- a chemical entity chosen from an antioxidant, a base or a weak acid, capable of trapping said chemical entity capable of initiating the crosslinking / polymerization reaction, and / or
one or more additives making it possible to improve the wetting and / or the adhesion, and / or the uniformity of the upper layer (30) of top coat (TC) deposited on the underlying layer (20), and / or
- one or more additives making it possible to absorb one or more ranges of light radiation of different wavelength, or to modify the electrical conductivity properties of the pre-polymer (pre-TC).
[7" id="c-fr-0007]
7. Method according to one of claims 1 to 6, characterized in that the crosslinking / polymerization reaction is obtained by radical route, or by cationic or anionic route, or results from a condensation or addition reaction between two derivatives having mutually compatible chemical functions.
[8" id="c-fr-0008]
8. Method according to claim 7, characterized in that when the polymerization is radical, the monomer (s) and / or dimer (s) and / or oligomer (s) and / or polymer (s) constituting (s) ) of the pre-polymer layer, is (are) chosen (s) from derivatives comprising unsaturations in their chemical structure, chosen from derivatives of acrylate or methacrylate or vinyl type.
[9" id="c-fr-0009]
9. Method according to claim 8, characterized in that the monomer (s) and / or dimer (s) and / or oligomer (s) and / or polymer (s) constituting the prepolymer layer, is (are) selected from derivatives of acrylates or di- or tri-acrylates or multi-acrylates, methacrylate, or multi-methacrylates, or polyglycidyl or vinyl, fluoroacrylates or fluoromethacrylates, vinyl fluorides or fluorostyrene, alkyl acrylate or methacrylate, hydroxyalkyl acrylate or methacrylate, alkylsilyl acrylate or methacrylate, unsaturated esters / acids such as fumaric or maleic acids, vinyl carbamates and carbonates, allyl ethers, and thiol systems -ènes.
[10" id="c-fr-0010]
10. Method according to claims 1 to 9, characterized in that when the polymerization / crosslinking is carried out by a radical route, the prepolymer composition (pre-TC) comprises a thermally activatable catalyst, chosen from derivatives of organic peroxide type, or still derivatives with a
Ref: 0560-ARK89 chemical function of azo type, such as azobisisobutyronitrile, or derivatives of alkyl halide type.
[11" id="c-fr-0011]
11. Method according to claim 7, characterized in that when the polymerization is cationic, the monomer (s) and / or dimer (s) and / or oligomer (s) and / or polymer (s) constituting (s) ) of the pre-polymer layer, are derivatives comprising chemical functions of the epoxy / oxirane type, or vinyl ethers, cyclic ethers, thiirane, thietanes, trioxane, vinyls, lactones, lactams, carbonates, thiocarbonates, maleic anhydride.
[12" id="c-fr-0012]
12. Method according to claims 1 to 7 and 11, characterized in that when the polymerization / crosslinking is carried out cationically, the prepolymer composition (pre-TC) comprises a thermally activatable catalyst, chosen from chemical derivatives making it possible to generate a thermally activated acid proton, such as ammonium salts such as ammonium triflate or trifluoroacetate, phosphoric or sulfuric or sulfonic acids, or onium salts, such as iodonium or phosphonium salts, or alternatively imidazolium salts.
[13" id="c-fr-0013]
13. Method according to claim 7, characterized in that when the polymerization / crosslinking results from a condensation / addition, the monomer (s) and / or dimer (s) and / or oligomer (s) and / or polymer (s) constituting the prepolymer layer are chosen from combination systems between:
- a derivative of thiol or polythiol type and a derivative of epoxy, thiol / nitrile, thiol / vinyl type; or between
- a derivative of silane or organosilane or halosilane type and a hydroxy or amino derivative; or between
- a derivative of amine or polyamine type and a derivative of isocyanate, amine / epoxy, amine / aldehyde, amine / ketone type.
[14" id="c-fr-0014]
14. Method according to claim 7, characterized in that when the polymerization is anionic, the monomer (s) and / or dimer (s) and / or oligomer (s) and / or polymer (s) constituting (s) ) of the pre-polymer layer, are derivatives of alkyl cyanoacrylates, epoxides / oxiranes, acrylates, or derivatives of isocyanates or polyisocynanates.
[15" id="c-fr-0015]
15. Method according to claim 14, characterized in that when the monomer (s) and / or dimer (s) and / or oligomer (s) and / or polymer (s) constituting the pre layer -polymer, are derivatives of the alkyl cyanoacrylate type, the reaction of
Ref: 0560-ARK89 crosslinking / polymerization can be spontaneous at room temperature and / or be catalyzed by ambient humidity.
[16" id="c-fr-0016]
16. Method according to claim 1 to 15, characterized in that the prepolymer composition comprises a mixture of monomer (s) and / or dimer (s) and / or oligomer (s) and / or polymer (s), preferably comprising epoxy / oxirane functions, and a catalyst making it possible to generate an acid and / or a co-reagent making it possible to generate a reagent making it possible to carry out an addition reaction on the epoxy functions.
[17" id="c-fr-0017]
17. The method of claim 16, characterized in that the catalyst is chosen from at least one of the following catalysts: amines or polyamines, such as diethylene triamine (DTA), isophorone diamine (IPD), 4 , 4'diaminodiphenylsulfone (DDS), hexamethylene diamine (HMDA), dicyandiamide (cyanoguanidine), or ammonium salts, such as ammonium triflate or ammonium trifluoroacetate, or ascorbic acid and its derivatives, chosen from sodium or magnesium ascorbate or sodium, magnesium or ammonium ascorbyl phosphate, as well as the various possible isomers (diastereoisomers, enantiomers) of ascorbic acid; uric acid; phenol, polyphenols and phenolic derivatives such as hydroquinone, resorcinol, 2,4pentanedione, malonaldéhyde (propanedial), tartronaldéhyde (2hydroxypropanedial), furanone and more generally reductones.
[18" id="c-fr-0018]
18. Method according to claim 16, characterized in that the co-reagent is chosen from at least one of the following reagents: thiols or polythiols such as pentaerythritol-tetrakis (3mercaptopropionate); imidazoles and imidazolium derivatives; acid anhydrides, such as, for example, succinic anhydride or even maleic anhydride; hydrazines.
[19" id="c-fr-0019]
19. Method according to one of claims 16 to 18, characterized in that the catalyst and / or the co-reactant is introduced into the pre-polymer composition with a mass content less than or equal to 80% of the total dry weight of the composition.
[20" id="c-fr-0020]
20. Method according to claims 1 and 15, characterized in that the prepolymer composition comprises a mixture of one or more multifunctional acrylic monomer (s), of cyanoacrylate type capable of generating a crosslinking / polymerization reaction so spontaneous at room temperature or moderate, in the presence of ambient humidity.
Ref: 0560-ARK89
[21" id="c-fr-0021]
21. The method of claim 20, characterized in that the cyanoacrylate type monomers are chosen from at least one of the following compounds: alkyl cyanoacrylate, linear or branched, such as methyl cyanoacrylate, ethyl cyanoacrylate , butyl cyanoacrylate, or octyl cyanoacrylate, neopentyl cyanoacrylate, octadecyl cyanoacrylate, or 2ethylphenyl cyanoacrylate, or alternatively alkylalkoxy cyanoacrylate, such as 2-ethoxylethylacrylate , or trifluroropropyl cyanoacrylate, or perfluororo alkyl cyanoacrylate.
[22" id="c-fr-0022]
22. Method according to one of claims 1 to 21, characterized in that the crosslinking / polymerization temperature of the layer of pre-polymer composition (pre-TC) is lower than the glass transition temperature Tg of the first layer of polymer (20) and in that the highest glass transition temperature Tg of the first layer of polymer (20) is greater than 25 ° C.
[23" id="c-fr-0023]
23. Method according to one of claims 1 to 22, characterized in that the pre-polymer composition (pre-TC) further comprises a solvent chosen from solvents or mixtures of solvents whose Hansen solubility parameters are such that δ _ρ > 10 MPa ^1/2 and / or ôh ^ 10 MPa ^1/2 , and with ôd <25 MPa ^1/2 .
[24" id="c-fr-0024]
24. The method of claim 23, characterized in that the solvent is chosen from alcoholic solvents such as methanol, ethanol, isopropanol, 1-methoxy-2-propanol, hexafluoroisopropanol; or water; dimethyl sulfoxide (DMSO); dimethylformamide; acetonitrile; diols such as ethylene glycol or propylene glycol; dimethylacetamide, gammabutyrolactone, ethyl lactate or a mixture of these.
[25" id="c-fr-0025]
25. Method according to one of claims 1 to 24, characterized in that the first polymer layer (20) is in a solid state when the stack is brought to a temperature below its glass transition temperature or in a state liquid-viscous when the stack is brought to a temperature above its glass transition temperature or at its highest glass transition temperature.
[26" id="c-fr-0026]
26. The method of claim 25, characterized in that the first polymer layer (20) is a block copolymer (BCP) capable of nanostructuring at an assembly temperature, said block copolymer being deposited on a layer underlying (10) whose surface is previously neutralized, said temperature
Ref .0560-ARK89 of assembly being lower than a temperature at which the top coat material (TC) behaves like a viscoelastic fluid, said temperature being higher than the glass transition temperature of said top coat material and preferably said assembly temperature is lower than the glass transition temperature of the top coat (TC) layer (30) in its crosslinked / polymerized form.
[27" id="c-fr-0027]
27. The method of claim 26, characterized in that the underlying layer (10) may or may not have patterns, said patterns being pre-drawn by a step or a sequence of lithography steps of any kind prior to the step of deposition of the first layer (20) of block copolymer (BCP), said patterns being intended to guide the organization of said block copolymer (BCP) by a technique called chemistry-epitaxy or graphoepitaxy, or a combination of these two techniques, to obtain a neutralized or pseudo-neutralized surface.
[28" id="c-fr-0028]
28. The method of claim 26 or 27, characterized in that the block copolymer comprises silicon in one of its blocks.
[29" id="c-fr-0029]
29. Method according to claim 26, characterized in that when the prepolymer composition comprises a mixture of one or more multifunctional acrylic monomer (s), of cyanoacrylate type, the crosslinking temperature of the layer of pre-composition polymer (pre-TC) is lower than the highest glass transition temperature Tg of the layer (20) of block copolymer (BCP) and the block copolymer has at least one block of which at least 40% of the composition has a glass transition temperature above 25 ° C.
[30" id="c-fr-0030]
30. Method according to one of claims 26 to 29, characterized in that the first layer (20) of block copolymer (BCP) is deposited on a thickness (e + E) at least equal to 1.5 times the minimum thickness of the block copolymer.
[31" id="c-fr-0031]
31. Method according to one of claims 26 to 30, characterized in that the pre-polymer composition (pre-TC) comprises a mixture of monomers and / or dimers and / or oligomers and / or polymers having the same chemical functions ensuring crosslinking and each carrying different chemical groups
Ref: 0560-ARK89
[32" id="c-fr-0032]
32. Method according to one of claims 26 to 31, characterized in that the composition of the prepolymer layer further comprises plasticizers and / or wetting agents, added as additives.
[33" id="c-fr-0033]
33. Method according to one of claims 1 to 32, characterized in that the composition of the prepolymer layer also comprises rigid co-monomers chosen from derivatives comprising either one / one or more aromatic rings in their structure, either mono or multicyclic aliphatic structures, and having a chemical function (s) adapted to the crosslinking / polymerization reaction targeted; and more particularly norbornene derivatives, isobornyl acrylate or methacrylate, styrenic, anthracene derivatives, adamantyl acrylate or methacrylate.
[34" id="c-fr-0034]
34. Method for manufacturing a nano-lithography mask from a polymeric stack obtained in accordance with the method according to one of claims 26 to 33, characterized in that once the top coat layer (30, TC) cross-linked, the stack is subjected to annealing for a determined period, at the assembly temperature of the block copolymer (BCP) so that it becomes nanostructured.
[35" id="c-fr-0035]
35. Method according to claim 34, characterized in that after the nanostructuring step of the block copolymer (BCP) the top coat layer (TC) is removed in order to leave a film of nanostructured block copolymer of minimum thickness ( e), then at least one of the blocks (21, 22) of said block copolymer, oriented perpendicular to the interfaces, is removed in order to form a porous film capable of serving as a mask for nano-lithography.
[36" id="c-fr-0036]
36. Method according to claims 30 and 35, characterized in that when the block copolymer is deposited on a thickness greater than the minimum thickness (e), an additional thickness (E) of said block copolymer is removed simultaneously or successively with the removal of the top coat layer (30, TC), in order to leave a film of nano-structured block copolymer of minimum thickness (e), then at least one of the blocks of said block copolymer, oriented perpendicular to the interfaces, is removed in order to form a porous film capable of serving as a mask for nano-lithography.
[37" id="c-fr-0037]
37. Method according to one of claims 35 to 36, characterized in that the top coat layer (30, TC) and / or the excess thickness (E) of the block copolymer and / or the block (s) (21,22 ) of the block copolymer is / are removed by dry etching.
Ref: 0560-ARK89
[38" id="c-fr-0038]
38. Method according to claim 37, characterized in that the steps of etching the top coat layer (30, TC) and / or the excess thickness (E) of the block copolymer (20, BCP) and one or more blocks (21, 22) of the block copolymer are produced successively in the same etching frame, by plasma etching.
[39" id="c-fr-0039]
39. Method according to one of claims 1 to 38, characterized in that at the time of the crosslinking / polymerization step of the top coat layer (30, TC), the stack is subjected to a localized heat treatment, on certain areas of the top coat layer, in order to create cross-linked / polymerized areas of top coat (TC) and non-cross-linked / non-polymerized areas (pre-TC).
[40" id="c-fr-0040]
40. Method according to claim 39, characterized in that the localized heat treatment is carried out by means of an infrared laser or by means of a so-called broadband light irradiation, or via a mechanical means such as a tip heating of an atomic force microscope, or even via a “roll-toroll” type process where a heated nanostructured roller is brought into contact with the polymer surface by printing.
[41" id="c-fr-0041]
41. Method according to claim 39 or 40, characterized in that in the context of the manufacture of a nano-lithography mask by directed assembly, the crosslinked / polymerized areas of top coat have a neutral affinity with respect to the underlying block copolymer, while the affinity of the non-crosslinked / non-polymerized top coat areas with respect to the blocks of the underlying block copolymer is not neutral.
[42" id="c-fr-0042]
42. Method according to one of claims 40 to 41, characterized in that after the localized heat-crosslinking of the top coat layer (30, TC), the stack is rinsed with the solvent which has allowed the deposition of the layer pre-polymer (pre-TC) to remove uncrosslinked / unpolymerized areas.
[43" id="c-fr-0043]
43. Method according to claims 41 and 42, characterized in that another pre-polymer material, not neutral with respect to the underlying block copolymer, is deposited in the zones previously not heat-treated and devoid of layer top coat, then said non-neutral pre-polymer material is subjected to a localized heat treatment in order to crosslink / polymerize it at predefined locations.
[44" id="c-fr-0044]
44. Method according to claims 26 and 41 to 43, characterized in that at the time of the annealing step of the stack at the assembly temperature (Tass) of the
Ref: 0560-ARK89 block copolymer (BCP), nano-domains (20, 21; 41, 42) are formed perpendicular to the interfaces in zones located opposite the zones of the crosslinked neutral top coat (TC) / polymerized, and nano-domains parallel to the interfaces in areas of the block copolymer located opposite the areas lacking a crosslinked / polymerized neutral top coat layer.
[45" id="c-fr-0045]
45. Polymeric stack comprising at least two layers of polymer (20, 30) stacked one on the other, characterized in that the upper layer (30), called top coat (TC), deposited on the first polymer layer ( 20) is obtained by in situ crosslinking according to the method according to one of claims 1 to 44, said stack being intended to be used in applications chosen from the production of coatings for the aerospace or aeronautics or automobile industries or wind power, inks, paints, membranes, biocompatible implants, packaging materials, or even optical components, such as optical filters for example, or microelectronic or optoelectronic components or micro components -fluidiques.
[46" id="c-fr-0046]
46. A stack according to claim 45, characterized in that it is intended for applications in the field of nano-lithography by directed self-assembly, in that the first polymer layer (20) is a block copolymer (BCP ) and in that the surfaces of the layer (10) on which the block copolymer is deposited and of the cross-linked top coat layer (TC) have a neutral surface energy vis-à-vis the blocks of the block copolymer.
Ref: 0560-ARK89

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法律状态:
2019-05-31| PLSC| Publication of the preliminary search report|Effective date: 20190531 |

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2019-10-14| PLFP| Fee payment|Year of fee payment: 3 |

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2020-10-13| PLFP| Fee payment|Year of fee payment: 4 |

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2021-11-09| PLFP| Fee payment|Year of fee payment: 5 |

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