• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:

    公开号:NL2005265A
    申请号:NL2005265
    申请日:2010-08-25
    公开日:2011-04-11
    发明作者:Jeroen Lammers；Sander Wuister；Yvonne Kruijt-Stegeman；Roelof Koole
    申请人:Asml Netherlands Bv；
    IPC主号:
    专利说明:

    Imprint Lithography Apparatus and Method
    FIELD
    The present invention relates to imprint lithography apparatus and methods formanufacture of devices.
    BACKGROUND
    In lithography, there is an ongoing desire to reduce the size of features in alithographic pattern in order to increase the density of features on a given substratearea. In photolithography, the push for smaller features has resulted in thedevelopment of technologies such as immersion lithography and extreme ultraviolet(EUV) lithography, which are however rather costly.
    A potentially less costly road to smaller features (e.g., nanometer sized features orsub micron sized features) that has gained increasing interest is so-called imprintlithography, which generally involves the use of a “stamp” (often referred to as animprint template or an imprint lithography template) to transfer a pattern onto asubstrate. An advantage of imprint lithography is that the resolution of the features isnot limited by, for example, the emission wavelength of a radiation source or thenumerical aperture of a projection system. Instead, the resolution is mainly limited tothe pattern density on the imprint template.
    Imprint lithography involves the patterning of an imprintable medium on a surface ofa substrate to be patterned. The patterning may involve bringing together apatterned surface of an imprint template and a layer of imprintable liquid medium(e.g., moving the imprint template toward the imprintable medium, or moving theimprintable medium toward the imprint template, or both) such that the imprintablemedium flows into recesses in the patterned surface and is pushed aside byprotrusions on the patterned surface. The recesses define pattern features of thepatterned surface of the imprint template. Typically, the imprintable medium isflowable when the patterned surface and the imprintable medium are broughttogether. Following patterning of the imprintable medium, the imprintable medium issuitably brought into a non-flowable or frozen state (i.e. a fixed state), for example byilluminating the imprintable medium with actinic radiation. The patterned surface ofthe imprint template and the patterned imprintable medium are then separated. Thesubstrate and patterned imprintable medium are then typically processed further in order to pattern or further pattern the substrate. The imprintable medium may beprovided in the form of droplets on the surface of a substrate to be patterned, butmay alternatively be provided using spin coating or the like.
    SUMMARY
    Imprint lithography, such as UV-imprint lithography, particularly, step and flashimprint lithography (SFIL), typically involves the dispensing of an array of droplets ofa curable imprintable liquid medium, such as a UV-curable photoresist onto asubstrate, followed by alignment of a patterned surface of an imprint template withthe array of droplets, or alignment of a patterned surface of an imprint template withthe substrate, and bringing together the patterned surface and substrate so that thepatterned surface of the imprint template contacts the droplets. The term “UV” isused here for convenience but should be interpreted as including any suitable actinicradiation for curing the imprintable liquid medium. As the patterned surface and/orthe substrate are moved and then held together for a filling period, the droplets mayspread out and flow to substantially fill recesses in the patterned surface. Gapsbetween the droplets may lead to voids at the interface between the patternedsurface and the imprintable liquid medium which may eventually disappear as theybecome filled with the imprintable liquid medium. Gas or vapor in such voids mayhave to be displaced by the imprintable liquid medium and so the filling of the voidsmay be time consuming if the gas or vapor must diffuse into the medium or thetemplate.
    The imprintable liquid medium is typically subsequently cured, for instance by UVradiation, with the imprint template and substrate held together for a holding period,with the curable imprintable liquid medium sandwiched between them. For UVimprint lithography, UV-irradiation may be directed through the imprint template,which is adapted to be transparent or translucent to UV-radiation, onto the UV-curable medium. For instance the imprint template may be of a material such asquartz. Once the UV-curable imprintable liquid medium has cured sufficiently suchthat the resulting patterned layer of cured medium is self-supporting, then the imprinttemplate may become out of contact with from the substrate and the resultingpatterned layer. By “self-supporting” it is meant that the patterned layer is ofsufficiently high viscosity or sufficiently gelled or solidified or hardened to maintainthe imprinted shape of the patterned surface once the imprint template has come out of contact with the substrate and the resulting patterned layer. The imprint templatemay then come into contact with other substrates, or to another part of the samesubstrate, and the process repeated. Patterns in the cured layers may be transferredto the underlying substrate by conventional etch techniques such as those commonlyused, for instance, in optical lithography.
    If any voids remain at the interface between imprintable liquid medium and thepatterned surface when the imprintable liquid medium is cured or solidified, these willbe present as undesirable defects in the resulting self-supporting patterned layer.Hence, it is desirable that the voids are substantially filled while the imprintable liquidmedium is still flowable.
    The time required to help ensure filling of voids, referred to as the filling period, maylead to a low throughput rate, compared to other lithography techniques, such asoptical lithography, and may be a problem for imprint lithography methods. The timetaken for the droplets of imprintable liquid medium to flow into the voids, to ensurethat the recesses of the patterned surfaces are substantially filled, may be one of themost time-consuming steps of the overall process typically in excess of 2 seconds.Because of the time taken for the imprintable liquid medium to flow into recesses tosubstantially fill them, the viscosity of the imprintable liquid medium should be keptas low as possible, until the voids are filled, to encourage flow. In UV imprintlithography, curing of the UV-curable imprintable liquid medium into a self-supportingpatterned layer commences after sufficient time has passed to ensure a highprobability that the recesses of the patterned surface have been filled. This is inorder to ensure that the viscosity of the UV-curable imprintable liquid medium is notincreased until the recesses of the patterned surface are sufficiently filled. Theholding period, during which curing typically occurs, often requires further time forcuring, for instance 0.5 to 1 seconds for UV imprint lithography, and so may alsomake a significant contribution to total process time.
    It is desirable, for example, to provide an imprint lithography method and apparatusthat enable the contribution of the time required to help ensure low defect levelsarising from voids to be reduced. It is desirable, for example, to provide an imprintlithography method and apparatus that allows more rapid separation of a patternedsurface of an imprint template and a patterned layer on a substrate formed by imprintlithography, particularly by UV-Imprint lithography such as SFIL, in order to increaseprocess throughput rates, without increasing the level of defects arising from voids. It is desirable, for example, to provide an imprint lithography method and apparatusthat enable the duration of the filling period and/or holding period to be reduced to aminimum while reducing or overcoming one or more problems in the prior art, orwhile providing an alternative method or apparatus to the prior art. It is desirable, forexample, to provide an imprint lithography apparatus and method which do notrequire substantial modifications to the physical features and characteristics of theimprint lithography apparatus or method, such that an embodiment of the inventionmay be put into effect by minor modifications to an existing imprint lithographyapparatus or method, particularly an UV imprint lithography apparatus or method.
    An embodiment of the invention provides an imprint method for forming a patternedlayer from an imprintable liquid medium on a substrate by means of an imprinttemplate having a patterned surface comprising recesses, the method comprising: providing the imprintable liquid medium on the substrate and/or patternedsurface as a flowable liquid, contacting together the patterned surface and the imprintable liquid mediumon the substrate and/or patterned surface for a filling period having an end timewhen the imprintable liquid medium has substantially filled the recesses in thepatterned surface, measuring light emergent from an interface between the imprintable liquidmedium and the patterned surface during the filling period to obtain data concerningone or more voids at the interface, and deriving an estimated end time from a relationship between the data and time.The relationship between the data and time may be a relationship based upon thevoids shrinking with time so that eventually even the largest voids may havevanished completely such that the liquid medium has substantially filled the recessesin the patterned surface. Hence the relationship between the data and time may bebased upon a diminution in the amount of radiation scattered, the size of voidsimaged, or the like as time progresses. The relationship may be based on theoreticaland/or empirical (i.e. practical) knowledge of how the data is expected to vary withtime as the filling period progresses.
    The features herein (e.g., the following features) are applicable to all the variousembodiments of the methods and apparatus of the invention where appropriate.When suitable, combinations of the following features may be employed as part ofthe method and apparatus described herein, for instance as set out in the clauses.
    The method and apparatus described herein are particularly suitable for UV-imprintlithography, particularly for step and flash imprint lithography (SFIL).
    The contacting together of the imprint template and substrate may not require thepatterned surface of the imprint template and the substrate to be parallel at initialcontact when the patterned surface first touches the imprintable liquid medium.
    The method may comprise directing the light from a light source onto the interface.By “light” in this specification is meant any suitable electromagnetic radiation such asvisible light, infra-red, ultra-violet and the like. If ultra violet light is used it shoulddesirably be of a wavelength that does not cure the imprintable liquid medium.Typically, the light may be visible light.
    By “emergent from the interface” is meant that the light is reflected, scattered,refracted or the like from the interface. Typically, the light will be reflected orscattered from the interface and any voids therein or thereat. The term “lightemergent from an interface between the imprintable liquid medium and the patternedsurface” should be taken to also include light emergent from the interface betweenthe patterned surface and gas/vapor in the voids at the interface.
    The voids at the interface are regions where the imprintable liquid medium has notyet reached during the filling period and so will be present at the interface as gasand/or vapor bubbles. In other words, the voids may contain gas or vapor but areempty of imprintable liquid medium. As the refractive index of the void may typicallybe different from that of the imprintable liquid medium, the surfaces between thevoids and the imprintable liquid medium and/or the patterned surface will reflect,refract or scatter light. The voids may include voids at the edges of the patternedsurface of the imprint template.
    The data may include information related to a size of the voids. The data mayinclude information related to a rate of change of the size of the voids. For instance,the data may relate to light scattered by voids in which case there may be arelationship between the size of the voids and the nature and/or intensity of the lightscattered.
    The light emergent from the interface may be focused to form an image of theinterface and voids and the image may be analyzed to select a set of voids fromwhich the data concerning one or more voids at the interface is obtained. In otherwords, a set of voids may be selected which are most likely to determine the endtime of the filling period, typically the largest voids. For instance, an imaging apparatus, such as a camera, may be used to form an image of the interface and/orvoids.
    The set of voids may be a set of voids wherein each void has a size larger than asize-related statistic for the voids. Commercially available image analysis softwaremay be used to measure the distribution of sizes for the voids, for instance based onthe distribution of the surface area based diameter for the voids (i.e. the diameter avoid would have if it were a circle having the same surface area as the void in theimage). From the distribution of sizes, a statistic such as the mean, median, dgo (thesize where 90% of voids by area have a size smaller than dgo) may be selected andonly the set of voids larger than the selected statistic used to generate the data. Theset of voids may be selected to be from a region of the image of the interface having,on average, larger voids than the remainder of the interface. For instance, the datamay be from a single void, for example the largest void present.
    The method may comprise a learning process by which the relationship betweendata and time is modified using information from defect levels arising from unfilledvoids in one or more previously patterned layers. Information about defect levelsmay be measured by any suitable method such as by image analysis. Where highdefect levels are found arising from voids still remaining at the estimated end time,the relationship may be adjusted to give an increase in the estimated end timederived from the data.
    A commencement time of one or more further processing steps may be determinedfrom the estimated end time. The commencement of a further processing step maybe before, during or after the estimated end time.
    For instance, when the imprintable liquid medium is a UV-curable medium, the oneor more further processing steps may include illuminating the UV-curable imprintableliquid medium with UV-radiation for an illumination period. The illuminating of the UV-curable imprintable liquid medium may, for instance commence prior to theestimated end time. This may be particularly useful where the UV-curableimprintable liquid medium exhibits an inhibition period during which it has a viscositywhich remains substantially unchanged (e.g. the viscosity does not increase by morethan 10% during the inhibition period) following the start of the UV illuminationperiod. For instance the UV-curable imprintable liquid medium may be an acrylateresist or a vinyl ether resist.
    Acrylates and silicon-containing acrylates are suitable monomers for use in the UV-curable imprintable liquid medium.
    The UV-curable imprintable liquid medium may be a medium which cures by meansof a reaction catalyzed by UV-generated catalyst. For instance, the UV-curableimprintable liquid medium may be a vinyl ether UV photoresist. Vinyl ethermonomers, particularly monomers including silicone groups, are of use in anembodiment of the invention (Kim et al, J. Vac Sci Tech B, 2005, 23, 2967). Thepolymerization of such vinyl ethers is thought to be initiated by acids, and photo-acidgenerators (PAGs) that form protons upon UV-illumination may be used as initiatormolecules.
    An embodiment of the invention provides an imprint method for forming a patternedlayer from an imprintable liquid medium on a substrate by means of an imprinttemplate having a patterned surface comprising recesses, the method comprising:providing the imprintable liquid medium on the substrate and/or patternedsurface as a flowable liquid, contacting the patterned surface with the imprintable liquid medium, andcalculating an estimated time required for the imprintable liquid medium tosubstantially fill the recesses in the patterned surface from data collected frommeasurement of light emergent from an interface between the imprintable liquidmedium and the patterned surface.
    An embodiment of the invention provides an imprint method comprising:providing an imprintable medium on a substrate as a flowable liquid,bringing a patterned surface of an imprint template and imprintable mediumon a substrate into contact with each other for a filling period having an end timewhen the imprintable medium has substantially filled recesses in the patternedsurface of the imprint template, measuring a light emergent from an interface between the imprintablemedium and the patterned surface of the imprint template during the filling period toobtain data concerning one or more voids at the interface, and estimating the end time of the filling period from a relationship between thedata and time.
    An embodiment of the invention provides an imprint apparatus comprising: an imprint holder configured to hold an imprint template, the imprint templatehaving a patterned surface to pattern an imprintable liquid medium on a substrate bycontact between the patterned surface and the imprintable liquid medium,a substrate table configured to hold the substrate, a detector configured to generate a signal derived from light emergent from aninterface between the imprintable liquid medium and the patterned surface, during afilling period as imprintable liquid medium substantially fills the recesses in thepatterned surface, and a computer configured to derive data from the signal concerning one or morevoids at the interface during the filling period, and to derive an estimated end time forthe filling period from a relationship between the data and time.
    In an embodiment, the imprint apparatus further comprises a dispenser for dispensing imprintable liquid medium onto the substrate
    An embodiment of the invention provides an imprint apparatus comprising: an imprint holder configured to hold an imprint template, the imprint templatehaving a patterned surface to pattern an imprintable liquid medium on a substrate bycontact between the patterned surface and the imprintable liquid medium,a substrate table configured to hold the substrate, a detector configured to collect and measure light emergent from an interfacecomprising one or more voids between the imprintable liquid medium and thepatterned surface and to generate a signal therefrom, and a computer configured to calculate an estimated end time required forthe imprintable liquid medium to substantially fill the recesses in the patternedsurface from data derived from the signal generated by the detectorIn an embodiment, the imprint apparatus further comprises a dispenser fordispensing imprintable liquid medium onto the substrate and/or a controller arrangedto control the operation of the apparatus.
    The following features are applicable to all the various embodiments of the methodand apparatus of an embodiment of the invention where appropriate. When suitable,combinations of the following features may be employed as part of the method andapparatus described herein, for instance as set out in the clauses.
    The apparatus may comprise a light source configured to direct light onto theinterface. Suitably, the apparatus may further comprise a focusing device configuredto form an image of the interface at the detector. For instance the apparatus may comprise a camera arranged to form an image of the interface. The detector and/orlight source may be positionable such that they do not obstruct any UV radiationintended for curing of the imprintable liquid medium. Hence, the detector and/or lightsource may for instance be positioned at a location over the substrate to enablecollection and measurement of light emergent from the interface and thenrepositioned to a location remote from the substrate prior to UV illumination of theimprintable liquid medium on the substrate.
    The apparatus may also comprise an image analyzer configured to analyze theimage to obtain the data from images of voids at the interface.
    The controller may be arranged to commence one or more further processing stepsat one or more commencement times determined from the estimated end time.
    These commencement times may be before, at or after the estimated end time.
    The imprintable liquid medium may be a UV-curable medium and the one or morefurther processing steps may comprise illuminating the UV-curable imprintable liquidmedium with UV radiation for an illumination period. For instance, the illumination ofthe UV-curable imprintable liquid medium may commence prior to the estimated endtime.
    An embodiment of the invention provides a controller for an apparatus according toan embodiment of the invention wherein the controller is arranged to commence oneor more further processing steps at one or more commencement times determinedfrom the estimated end time.
    BRIEF DESCRIPTION OF THE DRAWINGS
    Specific embodiments of the invention will be described with reference to theaccompanying figures, in which:
    Figure 1 schematically shows an example of UV-imprint lithography,
    Figures 2a to 2c schematically depict plan views of an area of a substrate with dropsof imprintable UV-curable liquid medium thereon as viewed through an imprinttemplate as the substrate and imprint template are contacted together,
    Figure 3 shows a graph with curves indicating how a parameter X derived from datarelating to the voids varies as a function of time,
    Figure 4 shows a graph of estimated end time for the filling period TE (as ordinate) asa function of parameter X (abscissa) measured at a measurement time TM, andFigures 5 and 6 show schematic timelines for the void filling period.
    DETAILED DESCRIPTION
    Figure 1 shows an example of UV imprint lithography, which involves the use of atransparent or translucent imprint template which is transmissive to UV and a UV-curable liquid as imprintable liquid medium (the term “UV” is used here forconvenience but should be interpreted as including any suitable actinic radiation forcuring the imprintable liquid medium). An UV-curable liquid is often less viscous thana thermosetting or thermoplastic resin used in hot imprint lithography andconsequently may move much faster to fill imprint template pattern features.
    A substrate 6 is provided with a planarization and transfer layer 8. UV-curableimprintable medium 10 is provided on the planarization and transfer layer 8. A quartzimprint template 12 is brought into contact (i.e. imprinted into) with the UV-curableimprintable medium 10. A pattern formed by pattern features of the quartz imprinttemplate 12 is frozen by curing the UV-curable imprintable medium 10 with UVradiation 14 that is applied through the quartz imprint template 12 onto the UV-curable imprintable medium 10. After removal of the imprint template 12, the UV-curable imprintable medium 10 is etched such that thinner areas of the UV-curableimprintable medium 10 are etched down to the substrate. A particular manner ofpatterning a substrate through UV imprint lithography is so-called step and flashimprint lithography (SFIL), which may be used to pattern a substrate in small steps ina similar manner to optical steppers conventionally used in IC manufacture. Thismay involve printing small areas of the substrate at a time by imprinting an imprinttemplate into UV-curable imprintable medium, “flashing” UV radiation through theimprint template to cure the UV-curable imprintable medium beneath the imprinttemplate, bringing the imprint template out of contact with the UV-curable imprintablemedium, stepping to an adjacent portion of the substrate and repeating theoperation.
    The small field size of such step-and-repeat processes may assist in reducingpattern distortions and critical dimension variations so that SFIL may be particularlysuited to the manufacture of integrated circuits and other devices requiring highoverlay accuracy.
    For more information on UV imprint, see e.g. U.S. Patent Application Publication No.2004-0124566, U.S. Patent No. 6,334,960, PCT Patent Application Publication No.WO 02/067055, and the article by J. Haisma entitled “Mold-assisted nanolithography: A process for reliable pattern replication”, J. Vac. Sci. Technol. B14(6), Nov/Dec1996.
    Figure 2a schematically depicts a plan view of an area 20 of a substrate as viewedthrough the imprint template (not shown in this Figure). The lines 20 are notnecessarily physically present and are merely present to demarcate an area of thesubstrate. An imprintable liquid medium dispenser has been used to provide aplurality of drops of imprintable liquid medium 21 on to the area 20 of the substrate.Once the drops of imprintable liquid medium have been provided on the substrate,the imprint template may be brought into contact with the drops of imprintable liquidmedium (by appropriate movement of the imprint template and/or the substrate).Figure 2b shows the drops of imprintable liquid medium 21 when the imprinttemplate has been brought into contact with the imprintable liquid medium for acertain time (imprint template is not shown in this Figure). Bringing the imprinttemplate into contact with the imprintable liquid medium causes the drops ofimprintable liquid medium 21 to spread out. The drops of imprintable liquid mediumcome into contact with one another and, at least to some extent, begin to coalesce.The imprint process may take place in a gaseous atmosphere such as helium. Thus,as the drops of imprintable liquid medium 21 come into contact with one another,pockets of gas 22 (e.g. pockets of helium gas) are trapped in-between the drops 21,the imprint template and the substrate to form voids at the interface between apatterned surface of the imprint template and the imprintable liquid medium.Although referred to as voids, these voids at the interface may be filled with gas orvapor. It is desirable to allow the voids to be filled by imprintable liquid medium,replacing the void as gas diffuses away from the void. In order for this to happen,time is needed to allow the gas to diffuse, for example into the substrate and/orimprint template, so that the voids may be filled.
    Figure 2c schematically depicts the locations of the voids remaining as they becomepartially filled relative to the area 20 of the substrate. Eventually the voids willdisappear completely. Any voids which are still present after the imprintable liquidmedium has been cured may give rise to defects in the resulting patterned layer ofcured medium and in any devices subsequently formed therefrom on and/or in thesubstrate.
    Although the droplets of imprintable liquid medium and voids are shown to be ofuniform size and spacing in the Figures, it will be apparent that in practice such regularity may not be present so that there may be a statistical distribution of voidsizes present at the interface at any particular time.
    Figure 3 shows a graph with curves showing how a parameter X derived from datarelating to the voids varies as a function of time. The ordinate axis shows X and theabscissa indicates time with the zero value of the abscissa corresponding to the startof the filling period Ts. Arbitrarily, the filling period may be considered to commenceas the imprint template first contacts the imprintable liquid medium. The parameter Xmay be any suitable parameter related to the voids at the interface at time t. In thisexample, when X=0 then the voids are completely filled. For instance, the parameterX may be the dgo value for the set of voids, where dgo is a size such that 90% by areaof voids have a diameter less than dgo· X may, for instance, be a parameter derivedby image analysis of an image of the interface.
    Figure 3 shows four curves schematically representative of the behavior of X as afunction of time. Curves A and D represent the most extreme behavior expectedfrom the statistical variation in voids at the interface within say 99.5% probabilityrange, leading to the least filling time Ta and the greatest filling time To expected.Curves 1 and 2 show typical behavior of X versus time between the extremes, withcurve 1 having a filling time TE. By measurement of Xat a time TM, where TM is at atime before TA and TE lies between TA and Td, it is possible to derive, fromknowledge of the shape of the curve 1, an estimated time TE by when the voidsshould be completely filled.
    In practice, the curves relating X to time may be measured for any particular system,i.e. arrangement of imprint lithography apparatus, substrate, imprint template,imprintable liquid medium, etc. From knowledge of the curves, the relationshipbetween TE and X(Tm) may be derived. Such a relationship is shown schematicallyin Figure 4 in a graph showing how TE as ordinate varies as a function of X(TM) asabscissa. The measurement time Tm is also indicated in Figure 4. Clearly, this mustbe earlier than any estimated time TE by which the voids are estimated to be filled.The relationship between X(TM) and TE is suitably obtained, theoretically orexperimentally, prior to putting an embodiment of the invention into practice for aparticular system. However, the relationship may be further modified by inclusion ofadditional information relating to the relationship between X(TM) and TE derived fromimprints carried out using the method of an embodiment of the invention. In other words, an embodiment of the invention may incorporate a learning process wherebythe relationship between X(Tm) and TEis refined during use.
    Rather than simply taking a measurement of X at a single time, TM, a measurementof X may be taken at time Tm and a measurement of ΔΧ may be taken at time Tm +ΔΤ. The difference between the measured values of X, ΔΧ, may be used to provideΔΧ / ΔΤ - a rate of change for X at TM. From the knowledge of ΔΧ / ΔΤ at TM and itsrelationship to TE derivable from curves of X versus time, the value of ΔΧ/ΔΤ maybe used to provide TE perhaps more accurately than by using X(TM) alone. Inanother embodiment the knowledge of ΔΧ / ΔΤ at TM alone is used to estimate TE.Prior to this embodiment, in order to ensure a high probability that the voids werefilled before moving on to the next step in processing, it would have been necessaryto extend the filling time to To or longer to ensure a high likelihood, such as 99.5%,that all voids had been eliminated from the interface prior to curing of the imprintableliquid medium.
    Figure 5 shows a time line for the filling period, commencing at Ts and proceedingfrom left to right with increasing time. The sequence of TM, TA and TD is shown. Bymeasurement of X(Tm) at Tm, Te may be derived from the curve in Figure 4, leadingto a reliable estimate of the time by which it is say 99.5% certain that all voids will befilled. This means that subsequent process steps do not have to be delayed until TD:it is only necessary to wait until TE.
    If an embodiment of the invention is applied to UV-imprint lithography, theimprintable liquid medium may be a UV-curable imprintable liquid medium. It may,for instance, be a UV-curable medium which exhibits an inhibition period.
    UV-curable imprintable media used in UV-imprint lithography may exhibit UV curingthat is initially inhibited for a short time. For instance, acrylate-type resists suffer fromoxygen inhibition. It has been demonstrated that oxygen dissolved in the resistformulation reacts with photo-generated radicals in an acrylate-initiator mixture (M.
    D. Dickey et al., AlChE J., 2005, 51,2547 and M. D. Dickey et al., AlChE J., 2006,52, 777). The radicals react with oxygen to form stable peroxy radicals, and thisreaction is rapid compared to the polymerization reaction. It is thought that thiscauses a certain inhibition time before the desired polymerization reaction ofacrylates takes place. The inhibition time may depend, for instance, upon initiatorconcentration, oxygen concentration, and UV power (M. D. Dickey et al., AlChE J.,2005, 51,2547). The inhibition time ranges from 0.5 s up to a few seconds.
    Vinyl ether-type resists also exhibit inhibition times of the order of 1 to 2 seconds (C.Decker et al., Progr. Org. Coat. 2001,42, 253). The underlying mechanism of theinhibition time in case of acid-catalyzed vinyl ether polymerization reaction is not wellunderstood. It was suggested by Decker et al. that there is a short delay between thephotolysis of the PAG (e.g. a sulfonium salt), and the actual production of protons.The inhibition period observed in the polymerization reaction of both acrylates andvinyl ethers may limit throughput for UV-imprint lithography processes. Previously,the initiation of UV illumination to cure the imprintable liquid medium would not takeplace until after all voids were gone. The viscosity (and other relevant physicalproperties) of the imprintable medium formulation do not change substantially duringthe inhibition period. In other words, the ability of the UV-curable imprintable liquidmedium 10 to flow into recesses of the patterned surface of an imprint template 12 isnot substantially impaired during the inhibition period.
    Hence, by commencing the UV-illumination prior to the estimated end time for voidfilling Te, it is possible to initiate the chemical processes which will eventually lead tocuring of the UV-curable imprintable liquid medium without substantially affecting thefilling of the recesses in the patterned surface of the imprint template 12. It is highlydesirable that the filling step should be completed (i.e. the recesses should besubstantially filled by the UV-curable liquid) before the inhibition period has elapsed.Following the end of the inhibition period, the viscosity of the UV-curable mediummay increase rapidly, which would slow or prevent the flow of the UV-curable liquidinto the recesses of the patterned surface of the imprint template 12.
    Because the UV-illumination period may be commenced some time before theestimated end time for void filling Te, the overall period from initial contact Ts tocompletion of the imprint may be reduced without any loss in the ability of the UV-curable medium to substantially fill the recesses in the patterned surface 12, yet withthe UV-illumination applied for the same length of time and at the same power as forprior art methods.
    An advantage of an embodiment of the invention is that only minor mechanicaladaptations or modifications to an existing UV-imprint lithography apparatus ormethod are required to implement an embodiment of the present invention, such asthe incorporation of a detector. Changes in the timing at which the process stepstake place may be effected by modifications to the software control of the apparatus.
    For instance the commencement of a UV illumination step may be commenced at orbefore TE rather than waiting until TD.
    The present invention relates to imprint lithography apparatus and methods. Theapparatus and/or methods may be used for the manufacture of devices, such aselectronic devices and integrated circuits or other applications, such as themanufacture of integrated optical systems, guidance and detection patterns formagnetic domain memories, flat-panel displays, liquid-crystal displays (LCDs), thinfilm magnetic heads, organic light emitting diodes, etc. In particular, the methods andapparatus are suitable for high resolution lithography, where features patterned ontoa substrate have a feature width or critical dimension of about 1 pm or less, typically100 nm or less or even 10 nm or less.
    Lithography may involve applying several patterns onto a substrate, the patternsbeing stacked on top of one another such that together they form a device such asan integrated circuit. Alignment of each pattern with a previously provided pattern isan important consideration. If patterns are not aligned with each other sufficientlyaccurately, then this may result in some electrical connections between layers notbeing made. This, in turn, may cause a device to be non-functional. Lithographicapparatus therefore usually includes an alignment apparatus, which may be used toalign each pattern with a previously provided pattern, and/or with alignment marksprovided on the substrate.
    Typically, the substrate is clamped to a substrate holder and the substrate holderand imprint template or imprint templates are moveable relative to each otherbetween imprints. Generally, a controller, such as a computer running a computerprogram, uses information from the alignment apparatus to control the positions ofthe substrate and the imprint template or templates relative to each other as eachpattern is imprinted.
    In the above embodiments, a single imprint template, a single imprint templateholder, a single substrate holder and a single substrate is provided in a singlechamber. In other embodiments, more than one imprint template, more than oneimprint template holder, more than one substrate holder, and/or more than onesubstrate may be provided in one or more chambers, in order for imprints to beundertaken more efficiently or quickly (e.g. in parallel). For example, in anembodiment, there is provided an apparatus that includes a plurality (e.g. 2, 3, or 4)of substrate holders. In an embodiment, there is provided an apparatus that includes a plurality (e.g. 2, 3, or 4) of imprint template arrangements. In an embodiment, thereis provided an apparatus configured to use one template holder arrangement persubstrate holder. In an embodiment, there is provided an apparatus configured touse more than one template holder arrangement per substrate holder. In anembodiment, there is provided an apparatus that includes a plurality (e.g. 2, 3, or 4)of imprintable liquid medium dispensers. In an embodiment, there is provided anapparatus configured to use one imprintable liquid medium dispenser per substrateholder. In an embodiment, there is provided an apparatus configured to use oneimprintable liquid medium dispenser per imprint template arrangement. In anembodiment, where an apparatus is provided that includes a plurality of substrateholders, the substrate holders may share functionalities in the apparatus. Forinstance, the substrate holders may share a substrate handler, a substrate cassette,a gas supply system (e.g. to create a helium environment during imprinting), animprint medium dispenser, and/or a radiation source (for curing the imprintable liquidmedium). In an embodiment, two or more of the substrate holders (e.g. 3 or 4) shareone or more functionalities of the apparatus (e.g. 1, 2, 3, 4, or 5 functionalities). In anembodiment, one or more functionalities (e.g. 1,2, 3, 4, or 5) of the apparatus areshared among all substrate holders.
    In order to aid release of the patterned surface from the imprintable liquid mediumafter patterning, the patterned surface may comprise a release layer comprising orconsisting essentially of titania, alumina, tantalum oxide or mixtures thereof, or maycomprise an organic release layer.
    The imprintable liquid medium may be hardened by actinic radiation, such as UVradiation, applied through the imprint template. In order to facilitate this, the poroussolid medium may be transmissive (i.e. transparent or translucent) to actinic radiationsuch as UV radiation. Silica is useful for this purpose.
    In this specification, the term “substrate” is meant to include any surface layersforming part of the substrate, or being provided on another substrate, such asplanarization layers or anti-reflection coating layers.
    While specific embodiments of the invention have been described above, it will beappreciated that the invention may be practiced otherwise than as described. Forexample, the invention may take the form of a computer program containing one ormore sequences of machine-readable instructions describing a method as disclosed above, or a data storage medium (e.g. semiconductor memory, magnetic or opticaldisk) having such a computer program stored therein.
    The descriptions above are intended to be illustrative, not limiting, Thus, it will beapparent to those skilled in the art that modifications may be made to the inventionas described without departing from the scope of the clauses set out below. Otheraspects of the invention are set out as in the following numbered clauses: 1. An imprint method for forming a patterned layer from an imprintable liquidmedium on a substrate by means of an imprint template having a patterned surfacecomprising recesses, the method comprising: contacting together the patterned surface and imprintable liquid medium onthe substrate and/or patterned surface for a filling period having an end time whenthe imprintable liquid medium has substantially filled the recesses in the patternedsurface, measuring light emergent from an interface between the imprintable liquidmedium and the patterned surface during the filling period to obtain data concerningone or more voids at the interface, and deriving an estimated end time from a relationship between the data and time.
    2. The imprint method of clause 1, comprising directing the light from a lightsource onto the interface.
    3. The imprint lithography method of clause 1 or clause 2, wherein the dataincludes information related to a size of the one or more voids.
    4. The imprint lithography method of any preceding clause, wherein the dataincludes information related to a rate of change of the size of the one or more voids.
    5. The imprint lithography method of any preceding clause, wherein the lightemergent from the interface is focused to form an image of the interface and theimage is analyzed to select a set of voids from which the data is obtained.
    6. The imprint lithography method of clause 5, wherein each of the voids in theset of voids has a size larger than a size-related statistic for the voids.
    7. The imprint lithography method of any preceding clause, further comprising alearning process by which the relationship is modified using information from defectlevels arising from remnants of unfilled voids in one or more previously patternedlayers.
    8. The imprint lithography method of any preceding clause, wherein acommencement time of one or more further processing steps is determined from theestimated end time.
    9. The imprint lithography method of clause 8, wherein the imprintable liquidmedium is a UV-curable medium and the one or more further processing stepscomprises illuminating the UV-curable medium with UV-radiation for an illuminationperiod.
    10. The imprint lithography method of clause 9, wherein the UV-curable mediumexhibits an inhibition period following illumination with UV-radiation during which ithas a viscosity which remains substantially unchanged.
    11. The imprint lithography method of clause 10, wherein illuminating the UV-curable imprintable liquid medium commences prior to the estimated end time.
    12. The imprint lithography method of clause 10 or clause 11, wherein the UV-curable imprintable liquid medium is an acrylate resist or a vinyl ether resist.
    13. An imprint method for forming a patterned layer from an imprintable liquidmedium on a substrate by means of an imprint template having a patterned surfacecomprising recesses, the method comprising: contacting the patterned surface with imprintable liquid medium on thesubstrate and/or patterned surface, and calculating an estimated time required for the imprintable liquid medium tosubstantially fill the recesses in the patterned surface from data collected frommeasurement of light emergent from an interface between the imprintable liquidmedium and the patterned surface.
    14. An imprint method comprising: bringing a patterned surface of an imprint template and imprintable mediumon a substrate into contact with each other for a filling period having an end timewhen the imprintable medium has substantially filled recesses in the patternedsurface of the imprint template, measuring a light emergent from an interface between the imprintablemedium and the patterned surface of the imprint template during the filling period toobtain data concerning one or more voids at the interface, and estimating the end time of the filling period from a relationship between thedata and time.
    15. An imprint apparatus comprising: an imprint holder configured to hold an imprint template, the imprint templatehaving a patterned surface to pattern an imprintable liquid medium on a substrate bycontact between the patterned surface and the imprintable liquid medium, a substrate table configured to hold the substrate, a detector configured to generate a signal derived from light emergent from aninterface between the imprintable liquid medium and the patterned surface, during afilling period as imprintable liquid medium substantially fills the recesses in thepatterned surface, and a computer configured to derive data from the signal concerning one or morevoids at the interface during the filling period, and to derive an estimated end time forthe filling period from a relationship between the data and time.
    16. An imprint apparatus comprising: an imprint holder configured to hold an imprint template, the imprint templatehaving a patterned surface to pattern an imprintable liquid medium on a substrate bycontact between the patterned surface and the imprintable liquid medium, a substrate table configured to hold the substrate, a detector configured to collect and measure light emergent from an interfacecomprising one or more voids between the imprintable liquid medium and thepatterned surface and to generate a signal therefrom, and a computer configured to calculate an estimated end time required for theimprintable liquid medium to substantially fill the recesses in the patterned surfacefrom data derived from the signal generated by the detector.
    17. The apparatus of clause 15 or clause 16, further comprising a light sourceconfigured to direct the light onto the interface.
    18. The apparatus of any of clauses 15 to 17, further comprising a focusingdevice arranged to form an image of the interface at the detector.
    19. The apparatus of clause 18, further comprising an image analyzer configuredto analyze the image to obtain the data from an image of the one or more voids atthe interface.
    20. The apparatus of any of clauses 15 to 19, further comprising a controllerconfigured to control operation of the apparatus, the controller arranged tocommence one or more further processing steps at one or more commencementtimes determined from the estimated end time.
    21. The apparatus of clause 20, wherein the imprintable liquid medium is a UV-curable medium and the one or more further processing steps comprises illuminatingthe UV-curable medium with UV-radiation for an illumination period.
    22. The apparatus of clause 21, wherein illuminating the UV-curable imprintableliquid medium commences prior to the estimated end time.
    23. A controller for an apparatus according to any of clauses 15 to 22 wherein thecontroller is arranged to commence one or more further processing steps at one ormore commencement times determined from the estimated end time.
    权利要求:
    Claims (1)
    [1]
    A lithography device comprising: an exposure device adapted to provide a radiation beam; a carrier constructed to support a patterning device, the patterning device being capable of applying a pattern in a section of the radiation beam to form a patterned radiation beam; a substrate table constructed to support a substrate; and a projection device adapted to project the patterned radiation beam onto a target area of the substrate, characterized in that the substrate table is adapted to position the target area of the substrate in a focal plane of the projection device.
    类似技术:
    公开号 | 公开日 | 专利标题
    NL2005265A|2011-04-11|Imprint lithography apparatus and method.
    US9278466B2|2016-03-08|Imprint lithography method and apparatus
    JP4557890B2|2010-10-06|Imprint lithography
    US8404170B2|2013-03-26|Imprint lithography apparatus and method
    US7692771B2|2010-04-06|Imprint lithography
    US7708924B2|2010-05-04|Imprint lithography
    US8696969B2|2014-04-15|Imprint lithography method and apparatus
    JP4515413B2|2010-07-28|Imprint lithography
    US9310700B2|2016-04-12|Lithography method and apparatus
    US9274441B2|2016-03-01|Inspection method for imprint lithography and apparatus therefor
    US9372399B2|2016-06-21|Imprint lithography method and imprintable medium
    US8454849B2|2013-06-04|Imprint lithography
    NL2005254A|2011-03-23|Imprint lithography method and apparatus.
    同族专利:
    公开号 | 公开日
    TWI396622B|2013-05-21|
    TW201132489A|2011-10-01|
    US20110079939A1|2011-04-07|
    US9547235B2|2017-01-17|
    JP5214698B2|2013-06-19|
    JP2011082514A|2011-04-21|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    JP2554857B2|1986-01-17|1996-11-20|東京エレクトロン株式会社|Asssing device|
    US20050037143A1|2000-07-18|2005-02-17|Chou Stephen Y.|Imprint lithography with improved monitoring and control and apparatus therefor|
    US6334960B1|1999-03-11|2002-01-01|Board Of Regents, The University Of Texas System|Step and flash imprint lithography|
    JP2001223148A|2000-02-08|2001-08-17|Nikon Corp|Cleaning method, method and device for exposure, and method of manufacturing device|
    EP1352295B1|2000-10-12|2015-12-23|Board of Regents, The University of Texas System|Template for room temperature, low pressure micro- and nano-imprint lithography|
    US7077992B2|2002-07-11|2006-07-18|Molecular Imprints, Inc.|Step and repeat imprint lithography processes|
    EP1680712B1|2003-11-06|2016-01-20|3D Systems, Inc.|Photocurable composition for producing cured articles having high clarity and improved mechanical properties|
    WO2005088629A1|2004-03-15|2005-09-22|Matsushita Electric Industrial Co., Ltd.|Multilayer information recording medium and process for producing the same|
    JP4480482B2|2004-06-24|2010-06-16|株式会社日立ハイテクノロジーズ|Plasma etching processing apparatus control method and trimming amount control system|
    EP1814817B1|2004-10-21|2011-03-23|Fujifilm Dimatix, Inc.|Method of etching using a sacrificial substrate|
    US7354698B2|2005-01-07|2008-04-08|Asml Netherlands B.V.|Imprint lithography|
    JP4515413B2|2005-05-27|2010-07-28|エーエスエムエルネザーランズビー．ブイ．|Imprint lithography|
    US7692771B2|2005-05-27|2010-04-06|Asml Netherlands B.V.|Imprint lithography|
    WO2006131153A1|2005-06-10|2006-12-14|Obducat Ab|Pattern replication with intermediate stamp|
    US7708924B2|2005-07-21|2010-05-04|Asml Netherlands B.V.|Imprint lithography|
    JP4533358B2|2005-10-18|2010-09-01|キヤノン株式会社|Imprint method, imprint apparatus and chip manufacturing method|
    US7360851B1|2006-02-15|2008-04-22|Kla-Tencor Technologies Corporation|Automated pattern recognition of imprint technology|
    JP4810496B2|2007-04-25|2011-11-09|株式会社東芝|Pattern forming apparatus, pattern forming method, and template|
    US8945444B2|2007-12-04|2015-02-03|Canon Nanotechnologies, Inc.|High throughput imprint based on contact line motion tracking control|
    JP4799575B2|2008-03-06|2011-10-26|株式会社東芝|Imprint method|
    NL2004945A|2009-08-14|2011-02-15|Asml Netherlands Bv|Imprint lithography apparatus and method.|US20130143002A1|2011-12-05|2013-06-06|Seagate Technology Llc|Method and system for optical callibration discs|
    WO2014085511A2|2012-11-27|2014-06-05|The Regents Of The University Of California|Polymerized metal-organic material for printable photonic devices|
    JP6669432B2|2015-02-05|2020-03-18|旭化成株式会社|Alignment method, imprint method, and imprint apparatus|
    JPWO2019198668A1|2018-04-09|2021-04-22|大日本印刷株式会社|Nanoimprint template and its manufacturing method, and two-stage mesa ranks and its manufacturing method|
    US10901327B2|2018-12-20|2021-01-26|Canon Kabushiki Kaisha|Automatic defect analyzer for nanoimprint lithography using image analysis|
    CN111054596B|2019-11-25|2022-02-01|歌尔股份有限公司|Gluing mold and UV glue coating method for electronic component|
    法律状态:
    2012-02-29| WDAP| Patent application withdrawn|Effective date: 20110617 |
    优先权:
    申请号 | 申请日 | 专利标题
    US24935109P| true| 2009-10-07|2009-10-07|
    US24935109|2009-10-07|
    [返回顶部]