Study on the properties of acrylic polymer dispersants coated on the abrasive particles of CMP slurries

Abstract

To provide a polishing slurry composition, and more specifically, a polishing slurry composition that has excellent thermal stability, dispersion stability, stability over time, and polishing efficiency compared to conventional polishing slurry compositions, and can minimize scratches on the surface to be polished.SOLUTION: A polishing slurry composition of the present invention has excellent thermal stability, dispersion stability, stability over time, and polishing efficiency, so it can be widely used in fields such as abrasives for semiconductor wafer processing, biomedical, pharmaceutical, cosmetics, and catalysts.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a polishing slurry composition, and more particularly to a polishing slurry composition that has superior thermal stability, dispersion stability, stability over time, and polishing efficiency compared to conventionally used polishing slurry compositions, and that can minimize scratches on the polished surface. [Background technology]

[0002] As semiconductor devices become more highly integrated and perform better, there is a growing trend toward finer wiring pattern line widths and more multi-layered structures. In order to improve the accuracy of photolithography, the flatness between layers in each process is extremely important.

[0003] Currently, the planarization technology that is receiving the most attention is the chemical-mechanical polishing (CMP) process, which is classified into oxide CMP, metal CMP, polysilicon (poly-Si) CMP, etc. depending on the material being polished.

[0004] Initially, CMP slurry compositions containing silica particles were mainly used to polish oxide films, but due to the need for high flatness due to the miniaturization of design rules and the thinning of devices, CMP slurry compositions containing cerium oxide particles, which have high polishing selectivity for wafers containing heterogeneous films, are now being used.

[0005] A CMP slurry composition containing cerium oxide particles has a high polishing rate for silicon oxide films but a low polishing rate for silicon nitride films, and therefore, when polishing step-like silicon oxide films and silicon nitride films together, the silicon oxide film is polished and the silicon nitride film is polished to completion, providing an etching stop function. Therefore, by applying a CMP slurry composition containing such cerium oxide particles to an oxide film CMP process, global planarization and precise control of the polishing thickness are possible.

[0006] On the other hand, the abrasive slurry composition generates a large amount of heat and bubbles during the dispersion process, which can cause aggregation and precipitation of dispersed particles, thereby increasing milling time, reducing workability and processability, and potentially causing scratches during polishing and reducing polishing efficiency.

[0007] Therefore, there is an increasing need for a polishing slurry composition that is excellent in thermal stability, dispersion stability, stability against changes over time, and polishing efficiency, and that can minimize scratches on the surface to be polished. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Korean Patent Publication No. 10-2013-0078791 Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention has been made to solve the above-mentioned problems, and aims to provide an abrasive slurry composition that has excellent thermal stability, dispersion stability, stability over time, and abrasive efficiency, and can minimize scratches on the surface to be polished. [Means for solving the problem]

[0010] The present invention relates to a polishing agent comprising: (a) at least one abrasive selected from aluminum oxide, silicon oxide, zirconium oxide, and cerium oxide; (b) at least one dispersant selected from ethylene-acrylic acid copolymers, salts of ethylene-acrylic acid copolymers, styrene-maleic acid copolymers, and styrene-acrylic acid copolymers; (c) a liquid carrier.

[0011] In one embodiment of the present invention, the composition comprises 5 to 45% by weight of an abrasive, 1 to 15% by weight of a dispersant, and the remaining amount of a liquid carrier.

[0012] In one embodiment of the present invention, the abrasive is cerium oxide.

[0013] In one embodiment of the present invention, the composition further comprises at least one pH adjuster selected from trimethanolamine, triethanolamine, trimethylammonium hydroxide, triethylammonium hydroxide, dimethylbenzylamine, ethoxybenzylamine, sodium hydroxide, and potassium hydroxide.

[0014] In one embodiment of the present invention, the composition further comprises 2 to 10 wt % of a silane coupling agent oligomer. [Effects of the Invention]

[0015] The present invention can provide a polishing slurry composition that is excellent in thermal stability, dispersion stability, stability against change over time, and polishing efficiency, and that can minimize scratches on the surface to be polished.

[0016] In addition, the polishing slurry composition of the present invention has excellent thermal stability, dispersion stability, stability over time, and polishing efficiency, and can be widely used in fields such as abrasives for semiconductor wafer processing, biomedical, pharmaceutical, cosmetics, and catalysts. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 2 is a graph showing the dispersibility of the polishing slurry composition of the present invention. [Figure 2] 1 is an OM image of the polishing slurry composition of the present invention. [Figure 3] FIG. 2 is a graph showing the contact angle of the polishing slurry composition of the present invention. [Figure 4]FIG. 2 is a graph showing the pH and conductivity of the polishing slurry composition of the present invention. [Figure 5] FIG. 2 is a diagram showing an IR spectrum of the polishing slurry composition of the present invention. [Figure 6] 1 is an SEM image of the polishing slurry composition of the present invention. [Figure 7] 1 is a TEM image of the polishing slurry composition of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] The present invention will be described in detail below with reference to examples. The terms, examples, etc. used in the present invention are merely illustrative examples to explain the present invention in more detail and to aid the understanding of those skilled in the art, and should not be construed as limiting the scope of the present invention.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the meaning commonly understood by one of ordinary skill in the art to which this invention belongs.

[0020] The present invention relates to a polishing agent comprising: (a) at least one abrasive selected from aluminum oxide, silicon oxide, zirconium oxide, and cerium oxide; (b) at least one dispersant selected from ethylene-acrylic acid copolymers, salts of ethylene-acrylic acid copolymers, styrene-maleic acid copolymers, and styrene-acrylic acid copolymers; (c) a liquid carrier.

[0021] The abrasive is used to polish the wafer surface, and any abrasive that is normally used in wafer CMP processes can be used without any restrictions on type.

[0022] For example, metal oxides may be mentioned, and more specifically, the metal oxide may contain at least one selected from aluminum oxide, silicon oxide, zirconium oxide, cerium oxide, titanium oxide, magnesium oxide, molybdenum oxide, etc., or may contain a chemical addition mixture thereof.

[0023] The abrasive may be selected from the group consisting of aluminum oxide, silicon oxide, zirconium oxide, cerium oxide, and combinations thereof, and more preferably, cerium oxide (ceria) is used because of its uniform particle size and low particle hardness.

[0024] The particle size of the abrasive is preferably 50 to 1,000 nm, and the particle size can be measured using a particle size distribution measuring instrument (Horiba Kikai, etc.) or by laser diffraction.

[0025] If the particle size of the abrasive is less than 50 nm, the polishing speed and polishing efficiency will decrease, and if it exceeds 1000 nm, scratches and defects on the polished surface will actually increase.

[0026] The method for producing the abrasive is not particularly limited as long as it is a method for producing metal oxide particles that is used in the art, and a solid phase method, a liquid phase method, or the like may be used.

[0027] The abrasive may be used in an amount of 5 to 45% by weight, preferably 5 to 20% by weight, based on 100% by weight of the total polishing slurry composition. If the abrasive content is less than 5% by weight, the polishing rate will decrease, and if it exceeds 45% by weight, the dispersibility of the composition will be low, which may cause a large number of scratches on the polished surface.

[0028] The dispersant may be used to bond to the surface of the abrasive to improve the dispersion stability and polishing performance of the polishing slurry composition.

[0029] The dispersant may be at least one selected from an ethylene-acrylic acid copolymer, a salt of an ethylene-acrylic acid copolymer, a styrene-maleic acid copolymer, and a styrene-acrylic acid copolymer.

[0030] In this case, examples of the salt of ethylene-acrylic acid copolymer that may be used include zinc salt of ethylene-acrylic acid copolymer, sodium salt of ethylene-acrylic acid copolymer, and magnesium salt of ethylene-acrylic acid copolymer.

[0031] The dispersant is coated on the surface of the abrasive to prevent aggregation and precipitation of the abrasive and reduce the particle size of the abrasive, thereby improving dispersibility and uniformity.

[0032] In the present invention, a mixture of an ethylene-acrylic acid copolymer and a salt of the ethylene-acrylic acid copolymer may be used as the dispersant, and in this case, the weight ratio of the ethylene-acrylic acid copolymer to the salt of the ethylene-acrylic acid copolymer is preferably 60-80:20-40.

[0033] When the weight ratio satisfies the above range, the polishing efficiency and dispersibility can be maximized.

[0034] The dispersant may be a mixture of an ethylene-acrylic acid copolymer, a salt of the ethylene-acrylic acid copolymer, and a styrene-maleic acid copolymer. In this case, the weight ratio of the ethylene-acrylic acid copolymer, the salt of the ethylene-acrylic acid copolymer, and the styrene-maleic acid copolymer is preferably 100:30 to 50:10 to 30.

[0035] When the weight ratio satisfies the above range, the polishing efficiency and dispersibility can be maximized.

[0036] The dispersant may be a mixture of ethylene-acrylic acid copolymer, a salt of ethylene-acrylic acid copolymer, a styrene-maleic acid copolymer, and a styrene-acrylic acid copolymer. In this case, the weight ratio of the ethylene-acrylic acid copolymer, the salt of ethylene-acrylic acid copolymer, the styrene-maleic acid copolymer, and the styrene-acrylic acid copolymer is preferably 100:30 to 50:10 to 30:5 to 20.

[0037] When the weight ratio satisfies the above range, the polishing efficiency and dispersibility can be maximized.

[0038] The dispersant is preferably contained in an amount of 1 to 15% by weight, and more preferably 3 to 10% by weight, based on 100% by weight of the total polishing slurry composition. If the dispersant content is less than 1% by weight, the dispersion stability decreases, and if it exceeds 15% by weight, many scratches occur on the polished surface, reducing the polishing efficiency.

[0039] The liquid carrier is used to disperse the abrasive, and any liquid may be used as long as it can be mixed with the abrasive and dispersant to form a dispersion or slurry. Suitable liquid carriers include polar solvents, preferably ultrapure water (deionized water), distilled water, etc.

[0040] The polishing slurry composition of the present invention may further contain a pH adjuster in order to maintain a constant zeta potential.

[0041] The pH adjuster is used to adjust the pH of the polishing slurry composition to a range of 8 to 11, and there are no limitations on the type as long as the object of the present invention can be achieved.

[0042] Examples include trimethanolamine, triethanolamine, trimethylammonium hydroxide, triethylammonium hydroxide, dimethylbenzylamine, ethoxybenzylamine, sodium hydroxide, and potassium hydroxide, and these may be contained in an amount of 0.0001 to 5% by weight relative to 100% by weight of the total slurry composition.

[0043] When the content satisfies the above range, the polishing efficiency and dispersibility can be maximized.

[0044] The polishing slurry composition may further contain a silane coupling agent oligomer to improve dispersibility.

[0045] The silane coupling agent oligomer may be produced by reacting an acrylate group-containing silane coupling agent, an epoxy group-containing silane coupling agent, 2-hydroxyethyl acrylate (HEA), and 2-hydroxyethyl methacrylate (HEMA).

[0046] The silane coupling agent oligomer binds to the surface of the abrasive to prevent aggregation and precipitation of the abrasive, and reduces the particle size of the abrasive, thereby improving dispersibility and uniformity.

[0047] Examples of the acrylate group-containing silane coupling agent include 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, methacryloxymethyltriethoxysilane, and methacryloxymethyltrimethoxysilane.

[0048] Examples of the epoxy group-containing silane coupling agent include 2-glycidoxyethylmethyldimethoxysilane, 2-glycidoxyethylmethyldiethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2-glycidoxyethyltrimethoxysilane, 2-glycidoxyethyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethylmethyldimethoxysilane, 2- Examples include (3,4-epoxycyclohexyl)ethylmethyldiethoxysilane, 3-(3,4-epoxycyclohexyl)propylmethyldimethoxysilane, 3-(3,4-epoxycyclohexyl)propylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, 3-(3,4-epoxycyclohexyl)propyltrimethoxysilane, and 3-(3,4-epoxycyclohexyl)propyltriethoxysilane.

[0049] The weight ratio of the acrylate group-containing silane coupling agent, the epoxy group-containing silane coupling agent, 2-hydroxyethyl acrylate (HEA), and 2-hydroxyethyl methacrylate (HEMA) is preferably 10-40:100:20-50:10-30, and when the weight ratio satisfies the above numerical range, polishing efficiency and dispersibility can be maximized.

[0050] The weight average molecular weight of the oligomer is preferably 5,000 to 50,000 g / mol.

[0051] The oligomer is preferably used in an amount of 2 to 10 wt % based on 100 wt % of the total polishing slurry composition. When the content is within this range, polishing efficiency and dispersibility can be maximized.

[0052] In addition, the polishing slurry composition may further contain a silane coupling agent oligomer prepared by reacting an acrylate group-containing silane coupling agent, an epoxy group-containing silane coupling agent, bisphenol A, 2-hydroxyethyl acrylate (HEA), and 2-hydroxyethyl methacrylate (HEMA) to improve dispersibility.

[0053] The weight ratio of the acrylate group-containing silane coupling agent, epoxy group-containing silane coupling agent, bisphenol A, 2-hydroxyethyl acrylate (HEA), and 2-hydroxyethyl methacrylate (HEMA) is preferably 10-40:100:15-35:20-50:10-30, and when the weight ratio satisfies the above numerical range, polishing efficiency and dispersibility can be maximized.

[0054] The weight average molecular weight of the oligomer is preferably 5,000 to 50,000 g / mol.

[0055] The oligomer is preferably used in an amount of 2 to 10 wt % based on 100 wt % of the total polishing slurry composition. When the content is within this range, polishing efficiency and dispersibility can be maximized.

[0056] The present invention may involve polishing the surface of a substrate with a slurry composition using a known polishing system, and the substrate may be of any type commonly used in the art, including, but not limited to, silicon oxide, silicon nitride, polycrystalline silicon, borophosphosilicate glass (BPSG), plasma-enhanced tetraethyl orthosilicate (PETEOS), thermal oxide, nitrogen-doped silicate glass, undoped silicate glass, high-density plasma (HDP) oxide, and the like.

[0057] In the present invention, the polishing system may be based on conventional techniques. For example, a wafer may be fixed to a polishing system including a fiber polishing pad, and the wafer may be pressed against the polishing pad while adjusting pressure, speed, and temperature conditions, and the pad and wafer may be moved relative to each other, and then a slurry composition may be sprayed onto the wafer to chemically and mechanically polish the film quality of the wafer.

[0058] The present invention will be described in detail below with reference to examples and comparative examples. The following examples are merely illustrative for carrying out the present invention, and the content of the present invention is not limited to the following examples. [Example]

[0059] 30% by weight of cerium oxide particles having an average particle size of 100 nm, ethylene-acrylic acid copolymer (dispersant), and the remaining amount of ultrapure water were added and stirred for 2 hours to prepare a polishing slurry composition.

[0060] At that time, the contents of the ethylene-acrylic acid copolymer used were 5 wt %, 6 wt % and 7 wt %.

[0061] FIG. 1 is a graph showing the dispersibility of the polishing slurry composition of the present invention.

[0062] Here, D104-5, D104-6 and D104-7 represent polishing slurry compositions containing ethylene-acrylic acid copolymer at 5 wt %, 6 wt % and 7 wt %, respectively.

[0063] Figure 1 shows the results of measuring the intensity of the particle size of the standard slurry and the prepared slurry using the laser diffraction / scattering method, based on the PSD and mean value, and the degree of aggregation of the particles and dispersant after 100 days at room temperature.

[0064] The results of the measurements confirmed that as the dispersant content increased, particle aggregation decreased and the original state was maintained. This is because the dispersant was better adsorbed onto the surface of the abrasive particles, increasing the electrostatic repulsion between particles and improving particle dispersibility.

[0065] FIG. 2 is an OM image of the polishing slurry composition of the present invention.

[0066] All three slurries showed uniform dispersion with no particle aggregation. In particular, the dispersibility of D104-5(a) and D104-6(b) was similar, while that of D104-7(c) was slightly different.

[0067] FIG. 3 is a diagram showing the contact angle of the polishing slurry composition of the present invention.

[0068] The contact angle measurement results show that as the content of dispersant in the slurry increases, the number of carboxyl groups increases, which increases hydrophilicity, and therefore the surface energy and work of adhesion also tend to increase.

[0069] FIG. 4 is a graph showing the pH and conductivity of the polishing slurry composition of the present invention.

[0070] The pH measurement confirmed that the pH remained constant even when the dispersant content increased. Meanwhile, the conductivity measurement showed a tendency for the measured conductivity to increase as the dispersant content increased. This is due to the influence of the ionic components contained in the dispersant and the difference in the amount of dispersant adsorbed on the ceria surface.

[0071] FIG. 5 is a diagram showing the IR spectrum of the polishing slurry composition of the present invention.

[0072] The IR spectra confirmed that the dispersant peaks were detected at the same locations in all three slurries, and that the dispersant peaks gradually increased as the dispersant content increased.

[0073] FIG. 6 is an SEM image of the polishing slurry composition of the present invention.

[0074] SEM analysis shows that the more dispersant content there is, the more small particles there are. This is because the higher the dispersant content, the better the dispersibility.

[0075] FIG. 7 is a TEM image of the polishing slurry composition of the present invention.

[0076] Analysis revealed that as the dispersant content increases, the dispersant adheres thicker and more stably to the abrasive surface and has a consistent orientation, which helps prevent scratches and defects caused by non-uniform orientation during CMP polishing. [Example]

[0077] A polishing slurry composition was prepared in the same manner as in Example 1, except that 3.5 wt% of ethylene-acrylic acid copolymer and 1.5 wt% of zinc salt of ethylene-acrylic acid copolymer were used instead of 5 wt% of ethylene-acrylic acid copolymer. [Example]

[0078] A polishing slurry composition was prepared in the same manner as in Example 1, except that 5% by weight of the dispersant mixture was used instead of 5% by weight of the ethylene-acrylic acid copolymer.

[0079] At that time, the dispersant mixture contained ethylene-acrylic acid copolymer, zinc salt of ethylene-acrylic acid copolymer, and styrene-maleic acid copolymer, and the weight ratio of ethylene-acrylic acid copolymer, zinc salt of ethylene-acrylic acid copolymer, and styrene-maleic acid copolymer was 100:40:20. [Example]

[0080] A silane coupling agent oligomer was prepared by reacting 3-methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 2-hydroxyethyl acrylate (HEA), and 2-hydroxyethyl methacrylate (HEMA).

[0081] Here, the weight ratio of 3-methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 2-hydroxyethyl acrylate (HEA), and 2-hydroxyethyl methacrylate (HEMA) was 30:100:30:20.

[0082] A polishing slurry composition was prepared in the same manner as in Example 1, except that 5 wt % of the silane coupling agent oligomer was further used.

[0083] (Comparative Example 1) A polishing slurry composition was prepared in the same manner as in Example 1, except that 5% by weight of sorbitan monolaurate was used instead of 5% by weight of ethylene-acrylic acid copolymer.

[0084] (Polished object) The wafers used were flat silicon oxide (PE-TEOS) and polysilicon (Poly) wafers. The silicon oxide wafer was made by depositing PE-TEOS to a thickness of 10,000 Å onto a silicon wafer. The polysilicon wafer was made by depositing polysilicon to a thickness of 3,000 Å onto a silicon wafer.

[0085] (CMP process conditions) The polishing process conditions are as shown in Table 1 below.

[0086] [Table 1]

[0087] (polishing speed) The thickness of the sample wafers before and after polishing was measured using an ST-5030 (K-MAC Corp.). To prevent measurement errors, 49 identical points were measured in the X-axis direction from the center to the edge of each wafer, and the measurements were averaged (unit: Å / min).

[0088] (uniformity) The uniformity of the wafers as samples after polishing was measured.

[0089] (Scratch or not) After polishing, the substrates were cleaned and then inspected under an optical microscope for defects or scratches, which were rated as outstanding, good, average, or poor.

[0090] The properties of the polishing slurry compositions obtained from the above Examples and Comparative Examples were measured and are shown in Table 2 below.

[0091] [Table 2]

[0092] The results in Table 2 show that the polishing rate increases, uniformity improves, and scratch occurrence is minimized in Examples 1 to 4. In particular, Examples 2 to 4 were confirmed to be the most excellent in these properties.

[0093] On the other hand, it is clear that Comparative Example 1 is inferior to the Examples in the above characteristics.

Claims

1. (a) 5 to 45 wt. % of at least one abrasive selected from aluminum oxide, silicon oxide, zirconium oxide, and cerium oxide; (b) 1 to 15 wt. % of a dispersant comprising an ethylene-acrylic acid copolymer, a salt of an ethylene-acrylic acid copolymer, and a styrene-maleic acid copolymer; (c) 2 to 10% by weight of a silane coupling agent oligomer; (d) a remaining amount of liquid carrier; the weight ratio of the ethylene-acrylic acid copolymer, the salt of the ethylene-acrylic acid copolymer, and the styrene-maleic acid copolymer is 100:30 to 50:10 to 30; The silane coupling agent oligomer has a structure derived from an acrylate group-containing silane coupling agent, an epoxy group-containing silane coupling agent, 2-hydroxyethyl acrylate (HEA), and 2-hydroxyethyl methacrylate (HEMA), a weight ratio of the acrylate group-containing silane coupling agent, the epoxy group-containing silane coupling agent, the 2-hydroxyethyl acrylate (HEA), and the 2-hydroxyethyl methacrylate (HEMA) is 10 to 40:100:20 to 50:10 to 30; The weight average molecular weight of the silane coupling agent oligomer is 5,000 to 50,000 g / mol.

2. 2. The polishing slurry composition of claim 1, wherein the abrasive is cerium oxide.

3. 3. The polishing slurry composition of claim 2, wherein the composition further comprises at least one pH adjuster selected from trimethanolamine, triethanolamine, trimethylammonium hydroxide, triethylammonium hydroxide, dimethylbenzylamine, ethoxybenzylamine, sodium hydroxide, and potassium hydroxide.

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