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    • 专利摘要:
    The present invention relates to a CMP slurry for polishing metal wires in semiconductor devices, and more particularly, to a CMP slurry for polishing metal wires in semiconductor devices including fine metal oxide powder, iron oxide compound, hydrogen peroxide, 4-methyl salicylic acid, and deionized water. When the slurry of the present invention is used, it is possible to prevent defects due to metal ion contamination while maintaining a high polishing rate in the CMP process, and to allow long-term storage of the slurry.
    公开号:KR20030001719A
    申请号:KR1020010037062
    申请日:2001-06-27
    公开日:2003-01-08
    发明作者:도원중；이재석；노현수；이길성
    申请人:제일모직주식회사；
    IPC主号:
    专利说明:

    CMP Slurry for Polishing Metal Wirings of Semiconductor Devices
    [1] The present invention relates to a CMP slurry for polishing metal wires in semiconductor devices, and more particularly, to a CMP slurry for polishing metal wires in semiconductor devices including fine metal oxide powder, iron oxide compound, hydrogen peroxide, 4-methyl salicylic acid, and deionized water. It is about.
    [2] Semiconductor devices are entering the era of ULSI, which is represented by 256M and 1G bit DRAM through high performance and high integration, and as the minimum processing size of device manufacturing is getting smaller, line widths such as 0.19μ and 0.13μ will be required for next-generation devices. It is a prospect. In the case of such a high-density device, in order to obtain a desired resolution during a lithography process, it is necessary to increase the performance of the stepper, increase the lens numerical aperture, and shorten the wavelength of light. However, if the lithography process is carried out under these conditions, the depth of focus (DOF) becomes shallow, so that sufficient resolution cannot be obtained when the level of the device surface is large. In addition, in order to construct a high-density integrated circuit, in addition to the miniaturization of the wiring structure, the number of wiring layers is also multiplied. In the case of logic semiconductors, the number of layers is increased to 6-7 layers, and in the case of DRAM, the number of layers is 2 ~. It is expected to increase to the third floor. The fact that the number of wiring layers is large means that the surface structure of the material is complicated and the degree of surface irregularities is increased.
    [3] The planarization technology has emerged as an important technique to solve the problems caused by the reduction of the depth of focus and the multilayer structure of the wiring structure in the lithography. The reason is that the global planarized surface is an ideal state for easy and accurate lithography and wiring formation.
    [4] Various methods such as Reflow / SOG Etch Back / ECR Depo & Etch have been proposed for the planarization, and some have been put into practical use, but partial planarization is the mainstream, and wide area planarization can be realized. Chemical Mechanical Polishing (CMP).
    [5] The principle of the CMP technology is to supply the polishing slurry with the wafer in contact with the polishing pad surface and perform an orbital motion with a mixture of rotational and linear motions to first chemically oxidize the metal layer on the wafer surface to generate metal oxides. This is removed by the abrasive component in the slurry to expose a new metal layer and the same process is repeated to planarize the uneven portion of the wafer surface. That is, the CMP process achieves improved and optimized planarization by selectively etching exposed portions of the wafer surface through chemical and physical actions.
    [6] Polishing slurries (hereinafter referred to as "CMP slurries") used in the CMP process are generally water-soluble suspensions and are composed of abrasives such as fine silica or alumina powders, oxidizing agents, pH adjusters, stabilizers and the like. The composition of the CMP slurry is an important factor in determining the efficiency of the CMP process, and its performance is determined by the role of the oxidizing agent, abrasive, and other additives contained in the slurry. CMP slurries should be chosen to meet the polishing rates required to polish metal layers while minimizing corrosion, erosion, scratches and contamination of the surface to be polished. In addition, the CMP slurry should be capable of selective polishing rate control for different abrasive layers such as titanium nitride or titanium.
    [7] As an example of a commercially available CMP slurry, US Pat. No. 5,244,534 discloses that slurry added with alumina and hydrogen peroxide and potassium or ammonium hydroxide is effective for polishing between tungsten and the insulating layer. In addition, U. S. Patent No. 5,209, 816 discloses CMP slurries containing perchloric acid, hydrogen peroxide, abrasives and the like.
    [8] However, most conventional CMP slurries contain metal ions because they use metal-based oxidants. If these metal ions remain on the wafer surface, not only will the electrical performance of the gate or contact within the wafer change, but also the performance of the dielectric layer. Such a change causes the long term reliability of the integrated circuit. Therefore, a slurry that minimizes metal ion contamination of the wafer should be used.
    [9] However, the nonmetallic oxidants have some problems due to the low polishing rate during tungsten polishing. If the tungsten polishing rate is slow, the polishing time may be long, resulting in over-polishing of the SiO 2 layer or corrosion. In particular, corrosion causes problems in resolution in subsequent lithography processes. In addition, the semiconductor manufacturing cost increases as the polishing rate decreases. Therefore, there is a need to develop a new CMP slurry that can minimize wafer contamination by metal ions while maintaining a high polishing rate.
    [10] Accordingly, the present invention can maintain a high polishing rate by the continuous recharge of the oxidizing power while minimizing the metal or metal ion content of the slurry by using the iron oxide compound and hydrogen peroxide as an oxidizing agent, and at the same time iron ions by 4-methyl salicylic acid It is an object of the present invention to provide a CMP slurry for polishing a metal wire of a semiconductor device by stabilizing the dispersion stability of the slurry.
    [11] That is, the present invention provides a CMP slurry for polishing a metal wire of a semiconductor device including a fine metal oxide powder, an iron oxide compound, hydrogen peroxide, 4-methyl salicylic acid, and deionized water.
    [12] Hereinafter, the CMP slurry of the present invention will be described in more detail.
    [13] CMP slurry of the present invention is prepared containing a fine metal oxide powder, iron oxide compound, hydrogen peroxide, 4-methyl salicylic acid, and deionized water, preferably
    [14] 1.0 to 15% by weight fine metal oxide powder;
    [15] 0.001-0.05 wt% iron oxide compound;
    [16] Hydrogen peroxide 1-4 wt%; And
    [17] 4-methylsalicylic acid 0.001-0.01% by weight
    [18] It is prepared to include.
    [19] The metal oxide fine powder used in the present invention serves as an abrasive, and metal oxide fine powders commonly used in CMP slurries may be used as long as the object of the present invention is not impaired. Preferably, silica (SiO 2 ) or alumina is used. (Al 2 O 3 ), ceria (CeO 2 ), and titania (TiO 2 ).
    [20] The content of the fine metal oxide powder is preferably 1.0 to 15% by weight relative to the total slurry, the outside of the content can not achieve the object of the present invention.
    [21] The iron oxide compound used in the present invention allows the metal layer to be polished by taking away the electrons of the metal layer deposited on the wafer surface during the CMP process. That is, since the tungsten layer deposited on the wafer surface is not thermodynamically stable, the surface is easily oxidized by the iron oxide compound. The tungsten layer on the oxidized surface is mechanically removed by friction between the abrasive and the pad, and the iron oxide compound continues chemical polishing to re-corrode the newly revealed tungsten layer. At this time, the hydrogen peroxide used together serves to oxidize the reduced iron ions again. In this way, continuous oxidation of the tungsten layer is achieved.
    [22] According to the present invention, the iron oxide compound used as the oxidizing agent contains iron ions (III) and is not particularly limited as long as it does not impair the object of the present invention, as described above, by reaction with the metal layer by hydrogen peroxide. Since the consumed oxidizing power is continuously recharged, it is possible to maintain a high polishing rate even if only a small amount of iron oxide compound is added to the slurry. For example, when the tungsten layer is polished by adding iron nitrate at 0.002% by weight to the entire slurry, the polishing rate may be 3,500 Pa / min or more.
    [23] In the present invention, the content of the iron oxide compound may have a sufficient polishing rate required in the CMP process when the 0.001 ~ 0.05% by weight relative to the total slurry, and more preferably 0.002 in consideration of defects and storage stability, including the polishing rate It is recommended to add at 0.02% by weight. On the other hand, when considering the content of the iron oxide compound, the content of hydrogen peroxide is preferably 1 to 4% by weight relative to the total slurry, the outside of the content can not achieve the object of the present invention.
    [24] 4-methyl salicylic acid (polyacrylic acid) used in the present invention serves to stabilize the iron ion (III). Iron ions agglomerate the abrasive in the slurry through the reaction with the abrasive in an aqueous solution, thereby lowering the dispersion stability of the slurry, which may cause storage problems when used for a long time, or may cause scratches during polishing. However, the present invention was able to solve this problem by stabilizing iron ions using 4-methyl salicylic acid. That is, the inventors have found that COOH - ions present in 4-methylsalicylic acid stabilize iron ions in the slurry by forming a stable chemical structure with iron ions.
    [25] In addition, 4-methyl salicylic acid has an effect of further improving the dispersion stability of the slurry by increasing the absolute value of the slurry zeta-potential value in addition to the stabilization effect of iron ions as described above. For example, CMP slurries that use silica as an abrasive have an isoelectric point in the range of pH 3-4, resulting in poor long-term dispersion stability. In addition, due to agglomeration of the abrasive, defects caused by scratches during polishing and the like have a non-uniform polishing rate. However, according to the present invention, this problem can be solved by adding an appropriate amount of 4-methylsalicylic acid to the CMP slurry.
    [26] For example, 0.002% by weight of iron nitrate and 0.005% by weight of 4-methylsalicylic acid are added to a slurry using silica as an abrasive, and the slurry is not added with 4-methylsalicylic acid after centrifugation at a rotational speed of 1,200 rpm for 120 minutes in a centrifuge. While it was observed that the upper layer became clear due to the precipitation of the abrasive and the abrasive particles precipitated in the lower layer, the slurry added with 4-methylsalicylic acid could not observe this precipitation phenomenon and thus the dispersion stability was improved.
    [27] In the present invention, the content of 4-methylsalicylic acid is preferably 0.001 to 0.01% by weight relative to the total slurry, more preferably 0.003 to 0.008% by weight when considering the content of the iron oxide compound. If the content of 4-methylsalicylic acid is less than 0.001% by weight can not achieve the object of the present invention, if it exceeds 0.01% by weight is not economical because it is not good.
    [28] In addition to the above components, nitric acid and / or acetic acid may be additionally added to the CMP slurry of the present invention as needed to maintain the pH of the slurry to about 3 to facilitate oxidation of the metal layer as needed. The content of the pH adjusting agent is preferably 0.03 to 0.1% by weight relative to the total composition, more preferably added in 0.03 to 0.05% by weight.
    [29] In addition, to the CMP slurry of the present invention, citric acid, which is usually used as an auxiliary oxidant, may be further added if necessary. At this time, the content of citric acid is preferably 1 to 5% by weight relative to the total composition.
    [30] Since the CMP slurry of the present invention having the composition as described above can achieve efficient polishing with the minimum content possible without further adding metal or metal ions during the CMP process, the possibility of defects caused by the metal or metal ion in the CMP process This is minimized.
    [31] The CMP slurry of the present invention is particularly effective for polishing tungsten layers, but can be applied evenly to polishing conductive layers and wiring materials of semiconductors such as titanium, titanium nitride, and aluminum in addition to tungsten.
    [32] Hereinafter, the present invention will be described in more detail with reference to examples, but these examples are for illustrative purposes only and should not be construed as limiting the present invention.
    [33] Example 1
    [34] 50 g of fine silica powder (Aerosil 90G, Degussa), 928.95 g of deionized water, 0.02 g of iron nitrate, 0.05 g of 4-methylsalicylic acid, 0.4 g of nitric acid, and 0.4 g of acetic acid were mixed in a 2 L polyethylene flask at 2,000 rpm for 90 minutes. . The mixture was dispersed once at 1,200 psi by high pressure dispersion to make a slurry. The slurry thus obtained was filtered using a 1 μm depth filter, and then 20 g of hydrogen peroxide (50%) was added and stirred to complete the CMP slurry.
    [35] After polishing the tungsten-deposited 6-inch wafer using the CMP slurry thus prepared for 1 minute under the following conditions, the polishing rate was measured from the thickness change removed by polishing.
    [36] [Abrasive performance evaluation method]
    [37] Grinding machine model: 6EC (Strasbaugh)
    [38] o Polishing condition:
    [39] -Pad Type: IC1000 / SubaⅣ Stacked (Rodel)
    [40] -Flattening Speed: 40rpm
    [41] Quill speed: 60 rpm
    [42] Pressure: 15psi
    [43] Background Pressure: 0psi
    [44] Temperature: 25 ℃
    [45] Slurry flow rate: 250 ml / min
    [46] Example 2
    [47] A CMP slurry was prepared in the same manner as in Example 1 except that 0.01 g of 4-methylsalicylic acid was added in Example 1, and the polishing performance was evaluated. The results are shown in Table 1 below.
    [48] Example 3
    [49] Except for using alumina instead of silica as an abrasive in Example 1 to prepare a CMP slurry in the same manner as in Example 1 and evaluated the polishing performance. The results are shown in Table 1 below.
    [50] Example 4
    [51] Except for using alumina instead of silica as an abrasive in Example 2 to prepare a CMP slurry in the same manner as in Example 2 and evaluated the polishing performance. The results are shown in Table 1 below.
    [52] Example 5
    [53] A CMP slurry was prepared in the same manner as in Example 1 except that 0.1 g of 4-methylsalicylic acid was added in Example 1, and the polishing performance was evaluated. The results are shown in Table 1 below.
    [54] Example 6
    [55] A CMP slurry was prepared in the same manner as in Example 1 except that 0.2 g of iron nitrate was added in Example 1, and the polishing performance was evaluated. The results are shown in Table 1 below.
    [56] divisionabrasiveIron nitrate (g)Hydrogen peroxide (g)4-methylsalicylic acid (g)Scratch * (dog / wafer)Polishing Speed (Å / min) Example 1SiO 2 0.02 g20 g0.05g353,750 Example 2SiO 2 0.02 g20 g0.01 g393,520 Example 3Al 2 O 3 0.02 g20 g0.05g453,860 Example 4Al 2 O 3 0.02 g20 g0.01 g573,790 Example 5SiO 2 0.02 g20 g0.1g313,350 Example 6SiO 2 0.2 g20 g0.05g693,810
    [57] * The scratch is a scratch of 0.3㎛ or more.
    [58] Comparative Example 1
    [59] A CMP slurry was prepared in the same manner as in Example 1 except that 4-methylsalicylic acid was not added in Example 1, and the polishing performance was evaluated. The results are shown in Table 2 below.
    [60] Comparative Example 2
    [61] Except that the iron nitrate was not added in Example 1 to prepare a CMP slurry in the same manner as in Example 1 and evaluated the polishing performance. The results are shown in Table 2 below.
    [62] Comparative Example 3
    [63] Except that hydrogen peroxide was not added in Example 1 to prepare a CMP slurry in the same manner as in Example 1 and evaluated the polishing performance. The results are shown in Table 2 below.
    [64] Comparative Example 4
    [65] A CMP slurry was prepared in the same manner as in Comparative Example 1 except that alumina was used as the abrasive in Comparative Example 1, and the polishing performance was evaluated. The results are shown in Table 2 below.
    [66] divisionabrasiveIron nitrate (g)Hydrogen peroxide (g)4-methylsalicylic acid (g)Scratch * (dog / wafer)Polishing Speed (Å / min) Comparative Example 1SiO 2 0.02 g20 g-632,280 Comparative Example 2SiO 2 -20 g0.05g412,410 Comparative Example 3SiO 2 0.02 g-0.05g521,010 Comparative Example 4Al 2 O 3 0.02 g20 g-662,060
    [67] * The scratch is a scratch of 0.3㎛ or more.
    [68] Example 7
    [69] After the long-term storage of the slurry prepared in Example 1 for 2 months, 4 months, and 6 months was evaluated for the polishing performance. The results are shown in Table 3 below.
    [70] Comparative Example 5
    [71] After the long-term storage of the slurry prepared in Comparative Example 1 for 2 months, 4 months, and 6 months, the polishing performance was evaluated in the same manner. The results are shown in Table 3 below.
    [72] Comparative Example 6
    [73] After the long-term storage of the slurry prepared in Comparative Example 2 for 2 months, 4 months, and 6 months, the polishing performance was evaluated in the same manner. The results are shown in Table 3 below.
    [74] divisionSlurryZeta potential (mV)SedimentationScratch * (dog / wafer)Polishing Speed (Å / min) 2 months4 months6 months Example 7Example 1-7.4-6.2-5.9radish313,520 Comparative Example 5Comparative Example 1-3.2-4.1-1.5U842,810 Comparative Example 6Comparative Example 2-6.8-6.1-5.4radish573,120
    [75] * The scratch is more than 0.3㎛ scratch.
    [76] As described in detail above, the use of the CMP slurry of the present invention can prevent defects due to metal ion contamination while maintaining a high polishing rate during the CMP process, and enables long-term storage of the slurry.
    权利要求:
    Claims (5)
    [1" claim-type="Currently amended] A CMP slurry for polishing metal wires in semiconductor devices comprising fine metal oxide powders, iron oxide compounds, hydrogen peroxide, 4-methylsalicylic acid, and deionized water.
    [2" claim-type="Currently amended] The method of claim 1,
    1.0 to 15% by weight of the fine metal oxide powder;
    0.001 to 0.05% by weight of the iron oxide compound;
    1 to 4 wt% of the hydrogen peroxide; And
    0.001-0.01 wt% of the 4-methylsalicylic acid
    CMP slurry for polishing metal wires of a semiconductor device, characterized in that it is included.
    [3" claim-type="Currently amended] The CMP slurry of claim 2, wherein the slurry further comprises 0.03 to 0.1% by weight of nitric acid and / or acetic acid as a pH adjusting agent.
    [4" claim-type="Currently amended] The CMP slurry of claim 2, wherein the slurry further comprises 1 to 5 wt% of citric acid as an auxiliary oxidant.
    [5" claim-type="Currently amended] The metal oxide fine powder of claim 1 or 2, wherein the metal oxide fine powder is selected from the group consisting of silica (SiO 2 ), alumina (Al 2 O 3 ), ceria (CeO 2 ), and titania (TiO 2 ). CMP slurry for polishing metal wires of a semiconductor device, characterized in that the fine powder of the oxide.
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    同族专利:
    公开号 | 公开日
    KR100458756B1|2004-12-03|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    法律状态:
    2001-06-27|Application filed by 제일모직주식회사
    2001-06-27|Priority to KR10-2001-0037062A
    2003-01-08|Publication of KR20030001719A
    2004-12-03|Application granted
    2004-12-03|Publication of KR100458756B1
    优先权:
    申请号 | 申请日 | 专利标题
    KR10-2001-0037062A|KR100458756B1|2001-06-27|2001-06-27|CMP Slurry for Polishing Metal Wirings of Semiconductor Devices|
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