Polishing composition

Abstract

To provide a new polishing composition that can suppress the number of PIDs after polishing while controlling a selection ratio.SOLUTION: Provided is a polishing composition comprising colloidal silica, an alkali metal salt, and a polymer compound having an amide bond, the polishing composition having a pH of 9.0 to 11.5, where (i) in an object to be polished including a first layer provided with a recess portion and a second layer formed so that the inside of the recess portion is filled, the polishing composition is used in a step of polishing the second layer to expose the first layer, the first layer being selected from those having an oxygen-silicon bond or having a nitrogen-silicon bond, and the second layer having a silicon-silicon bond, and / or (ii) the number of silanol groups in the colloidal silica is 6 / nm2 or more and 22 / nm2 or less.

Description

[Technical Field]

[0001] The present invention relates to a polishing composition. [Background technology]

[0002] In the field of CMP, a silicon dioxide film having recesses is sometimes placed next to a polysilicon film formed to fill the recesses, and polishing is performed using the silicon dioxide film as a stopper film. The selectivity, which is the ratio of the rate at which the polysilicon film is polished to the rate at which the silicon dioxide film is polished, is used as an index of how easily the polysilicon film is polished relative to the silicon dioxide film. This is calculated by dividing the rate at which the polysilicon film is polished by the rate at which the silicon dioxide film is polished. For example, Patent Document 1 proposes a polishing composition that achieves a high selectivity and minimizes the occurrence of surface defects. The polishing composition contains an abrasive such as silicon dioxide and water, and may further contain a basic organic compound such as tetramethylammonium hydroxide.

[0003] Silicon nitride is also sometimes used as a stopper film, and in this case, it is preferable that the ratio of the polishing rate of the material other than silicon nitride to the polishing rate of silicon nitride is large. As an example of using silicon nitride as a stopper film, Patent Document 2 discloses a chemical mechanical polishing composition that contains silica, aminophosphonic acid, polysaccharide, tetraalkylammonium salt, bicarbonate, a compound containing an azole ring, and optionally potassium hydroxide and water, and has a pH of 7 to 11. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 10-321569 [Patent Document 2] Special Publication No. 2014-505358 Summary of the Invention [Problem to be solved by the invention]

[0005] In the process of developing a new polishing composition, the present inventors discovered that conventional techniques have the problem that the number of PIDs (Polish Induced Defects) increases after polishing, even if the selectivity is controlled.

[0006] Therefore, an object of the present invention is to provide a novel polishing composition that can suppress the number of PIDs after polishing while controlling the selectivity. [Means for solving the problem]

[0007] One aspect of the present invention is a polishing method for a polishing object having a first layer with a recess formed therein and a second layer formed so as to fill the recess, the polishing method comprising: polishing a first layer to expose the first layer; polishing a second layer to expose the first layer; and polishing a second layer to expose the first layer; wherein the first layer has an oxygen-silicon bond or a nitrogen-silicon bond, and the second layer has a silicon-silicon bond. The polishing method for a polishing object having a first layer with a recess formed therein and a second layer formed so as to fill the recess, ... second layer has an oxygen-silicon bond or a nitrogen-silicon bond. The polishing method for a polishing object having a first layer with a recess formed therein and a second layer formed so as to fill the recess, the second layer has an oxygen-silicon bond or a silicon-silicon bond. The polishing method for a polishing object having a first layer with a recess formed therein and a second layer formed so as to fill the recess, the second layer has an 2 More than 22 pieces / nm 2 A polishing composition comprising: [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a novel polishing composition that can suppress the number of PIDs after polishing while controlling the selectivity. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic cross-sectional view of an object to be polished before polishing. [Figure 2] FIG. 2 is a schematic cross-sectional view of a polished object after ideal polishing. [Figure 3] FIG. 3 is a schematic cross-sectional view of a polished object that has not been ideally polished and has a recess as a defect. [Figure 4] FIG. 4 is a schematic cross-sectional view of a polished object in which defects remain that should ideally be polished but are not polished. [Figure 5] FIG. 5 is a schematic cross-sectional view of a polished object showing the simultaneous occurrence of the defects of FIGS. 3 and 4. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] In this specification, "X to Y" means "X or more and Y or less," with the preceding and following numerical values ​​(X and Y) being included as upper and lower limits. When multiple "X to Y" are used, for example, "X1 to Y1" or "X2 to Y2," the disclosure of each numerical value as an upper limit, the disclosure of each numerical value as a lower limit, and combinations of these upper and lower limits are all disclosed (i.e., they serve as legitimate grounds for correction). Specifically, corrections of X1 or more, corrections of Y2 or less, corrections of X1 or less, corrections of Y2 or more, corrections of X1 to X2, and corrections of X1 to Y2, etc., must all be deemed legitimate. Unless otherwise specified, operations and measurements of physical properties are performed at room temperature (20 to 25°C) and a relative humidity of 40 to 50% RH. The concentrations described herein may be concentrations at the point of use (POU) or concentrations before dilution to the POU concentration. The dilution ratio may be 2 to 10 times. Furthermore, it should be understood that all combinations of embodiments and explanations disclosed in this specification are disclosed in the present application. In other words, it should be understood that they can be used as a basis for amendment. Furthermore, when the content or concentration of each component is described, if two or more components are included, it may be the total amount.

[0011] <Polishing composition> One aspect of the present invention is a polishing method for a polishing object having a first layer with a recess formed therein and a second layer formed so as to fill the recess, the polishing method comprising: polishing a first layer to expose the first layer; polishing a second layer to expose the first layer; and polishing a second layer to expose the first layer; wherein the first layer has an oxygen-silicon bond or a nitrogen-silicon bond, and the second layer has a silicon-silicon bond. The polishing method for a polishing object having a first layer with a recess formed therein and a second layer formed so as to fill the recess, ... second layer has an oxygen-silicon bond or a nitrogen-silicon bond. The polishing method for a polishing object having a first layer with a recess formed therein and a second layer formed so as to fill the recess, the second layer has an oxygen-silicon bond or a silicon-silicon bond. The polishing method for a polishing object having a first layer with a recess formed therein and a second layer formed so as to fill the recess, the second layer has an 2 More than 22 pieces / nm 2 The polishing composition is as follows. This embodiment makes it possible to provide a novel polishing composition that can suppress the number of PIDs after polishing while controlling the selectivity. More specifically, the polishing composition of one embodiment of the present invention can suppress the number of PIDs of a polished object having silicon-silicon bonds (particularly polished polysilicon) after CMP, which leaves patterned wiring.

[0012] [Abrasive grain] A polishing composition according to one embodiment of the present invention contains colloidal silica as abrasive grains. The abrasive grains have the function of mechanically polishing an object to be polished. Colloidal silica can be produced by a sol-gel method. For example, colloidal silica can be obtained by a hydrolysis-condensation reaction using a hydrolyzable silicon compound (e.g., an alkoxysilane or its derivative) as a raw material.

[0013] According to one embodiment of the present invention, the number of silanol groups in the colloidal silica is 6 / nm 2 More than 22 pieces / nm 2 The number of silanol groups in colloidal silica is 6 / nm 2 More than 22 pieces / nm 2 Although the detailed mechanism is unknown, it is surprising that the number of PIDs after polishing can be reduced by using the following: 2 More than 22 pieces / nm 2An example of a method for controlling the following is hydrothermal treatment of a dispersion containing colloidal silica. The hydrothermal treatment conditions include heat treating the dispersion containing colloidal silica at a temperature of 100°C to 200°C for 30 to 60 minutes.

[0014] According to one embodiment of the present invention, the number of silanol groups in the colloidal silica is 6.1 / nm 2 More than 6.2 pieces / nm 2 More than 6.3 pieces / nm 2 More than 6.4 pieces / nm 2 More than 6.5 pieces / nm 2 More than 6.6 pieces / nm 2 More than 6.6 pieces / nm 2 Super, 6.7 pieces / nm 2 More than 6.8 pieces / nm 2 More than 6.9 pieces / nm 2 More than 7.0 pieces / nm 2 More than 7.1 pieces / nm 2 More than 7.2 pieces / nm 2 More than 7.3 pieces / nm 2 More than 7.4 pieces / nm 2 More than 7.5 pieces / nm 2 More than 7.6 pieces / nm 2 More than 7.7 pieces / nm 2 More than 7.8 pieces / nm 2 More than 9 pieces / nm 2 More than 10 pieces / nm 2 More than 12 pieces / nm 2 More than 14 pieces / nm 2 or more, or 16 / nm 2 That's all.

[0015] According to one embodiment of the present invention, the number of silanol groups in the colloidal silica is 21 / nm 2 Below, 20 pieces / nm 2 Below, 19 pieces / nm 2 Below, 18 pieces / nm 2 Below, 17.5 pieces / nm 2 Less than 17 particles / nm 2 Below, 16 pieces / nm 2 Below, 15 pieces / nm 2 Below, 14 pieces / nm 2 Below, 13 pieces / nm2 Below, 12 pieces / nm 2 Below, 11 pieces / nm 2 Below, 10 pieces / nm 2 Below, 9 pieces / nm 2 Below, 8 pieces / nm 2 or less, or 7 particles / nm 2 The number of silanol groups was measured by the method described in the Examples.

[0016] According to one embodiment of the present invention, the pulsed NMR specific surface area of ​​the colloidal silica is 40 m 2 According to one embodiment of the present invention, the pulse NMR specific surface area of ​​the colloidal silica is 39 m 2 / g or less, 38m 2 / g or less, 37m 2 / g or less, 36m 2 / g or less, 35m 2 / g or less, 34m 2 / g or less, 33m 2 / g or less, 32m 2 / g or less, 31m 2 / g or less, 30m 2 / g or less, 29m 2 / g or less, 28m 2 / g or less, 27m 2 / g or less, 26m 2 / g or less, 25m 2 / g or less, or 24m 2 According to one embodiment of the present invention, pulsed NMR of colloidal silica is 2 / g or more, 15m 2 / g or more, or 20m 2 / g or more. The pulse NMR specific surface area of ​​abrasive grains (particularly colloidal silica) is measured by the method described in the Examples. The pulse NMR specific surface area of ​​colloidal silica measures the manner in which the relaxation rate of proton resonance changes depending on the amount of molecules adsorbed on the solid surface, and can be controlled by increasing or decreasing the number of protons in the functional groups on the colloidal silica surface.

[0017] According to one embodiment of the present invention, the lower limit of the average primary particle size of the abrasive grains (particularly colloidal silica) is 60 nm or more, 70 nm or more, more than 70 nm, 71 nm or more, 72 nm or more, 73 nm or more, 74 nm or more, 75 nm or more, 76 nm or more, 77 nm or more, 78 nm or more, 79 nm or more, 80 nm or more, 81 nm or more, 82 nm or more, 83 nm or more, 84 nm or more, 85 nm or more, 86 nm or more, 87 nm or more, 88 nm or more, 89 nm or more, or 95 nm or more.

[0018] According to one embodiment of the present invention, the upper limit of the average primary particle size of the abrasive grains (particularly colloidal silica) is 110 nm or less, less than 100 nm, 99 nm or less, 98 nm or less, 97 nm or less, 96 nm or less, 95 nm or less, 94 nm or less, 93 nm or less, 92 nm or less, or 91 nm or less. According to one embodiment of the present invention, the average primary particle size of the colloidal silica is more than 70 nm and less than 100 nm. The average primary particle size is measured by the method described in the Examples.

[0019] According to one embodiment of the present invention, the lower limit of the average secondary particle diameter of the abrasive grains (particularly colloidal silica) is 110 nm or more, 120 nm or more, 130 nm or more, 140 nm or more, 150 nm or more, 160 nm or more, 170 nm or more, 180 nm or more, 190 nm or more, 200 nm or more, 210 nm or more, or 215 nm or more.

[0020] According to one embodiment of the present invention, the upper limit of the average secondary particle size of the abrasive grains (particularly colloidal silica) is 350 nm or less, 340 nm or less, 330 nm or less, 320 nm or less, 310 nm or less, 300 nm or less, 290 nm or less, 280 nm or less, 270 nm or less, 260 nm or less, 250 nm or less, 240 nm or less, 230 nm or less, or 225 nm or less. The average secondary particle size is measured by the method described in the Examples.

[0021] According to one embodiment of the present invention, the average degree of association (average secondary particle size / average primary particle size) of the abrasive grains (particularly colloidal silica) is 1.6 or more, 1.7 or more, 1.8 or more, 1.9 or more, 2.0 or more, 2.1 or more, 2.2 or more, 2.3 or more, or 2.4 or more.

[0022] According to one embodiment of the present invention, the average degree of association (average secondary particle size / average primary particle size) of the abrasive grains (particularly colloidal silica) is 4.6 or less, 4.4 or less, 4.2 or less, 4.0 or less, 3.8 or less, 3.6 or less, 3.4 or less, 3.2 or less, 3.0 or less, 2.9 or less, 2.8 or less, 2.7 or less, 2.6 or less, or 2.5 or less.

[0023] According to one embodiment of the present invention, the content of abrasive grains (particularly colloidal silica) in the polishing composition is 0.01 mass% or more, 0.05 mass% or more, 0.1 mass% or more, 0.5 mass% or more, 0.6 mass% or more, 0.7 mass% or more, 0.8 mass% or more, 0.9 mass% or more, 1.0 mass% or more, 1.1 mass% or more, 1.2 mass% or more, 1.3 mass% or more, or 1.4 mass% or more.

[0024] According to one embodiment of the present invention, the content of abrasive grains (particularly colloidal silica) in the polishing composition is 10 mass % or less, 5 mass % or less, 3 mass % or less, or 2 mass % or less.

[0025] According to one embodiment of the present invention, the colloidal silica accounts for 90% by mass or more, 95% by mass or more, 98% by mass or more, 99% by mass or more, 99.5% by mass or more, or 99.9% by mass or more of the abrasive grains contained in the polishing composition (the upper limit is 100% by mass).

[0026] According to one embodiment of the present invention, the surfaces of the abrasive grains (particularly colloidal silica) contained in the polishing composition have not been treated to chemically bond a treating agent such as an organic acid (e.g., sulfonic acid or carboxylic acid).

[0027] [Alkali metal salts] The polishing composition of one embodiment of the present invention contains an alkali metal salt. If the polishing composition does not contain an alkali metal salt, the amount of remaining polished material, such as polysilicon, may not be reduced, or recessing may be promoted.

[0028] According to one embodiment of the present invention, the alkali metal salt contains at least one of an alkali metal hydroxide and an alkali metal carbonate. According to one embodiment of the present invention, the alkali metal salt contains an alkali metal hydroxide. According to one embodiment of the present invention, the alkali metal hydroxide contains potassium hydroxide. As the alkali metal salt, an alkali metal hydroxide is preferable compared to an alkali metal carbonate from the viewpoint of reducing residual metal. Examples of alkali metals include potassium, sodium, and lithium, and among them, potassium is particularly preferable from the viewpoint of reducing residual metal.

[0029] The alkali metal salt also functions as a pH adjuster that adjusts the pH of the polishing composition. According to one embodiment of the present invention, the content of the pH adjuster (particularly the alkali metal salt) contained in the polishing composition is an amount appropriate for adjusting the polishing composition to a predetermined pH (particularly a pH of 9.0 to 11.5).

[0030] According to one embodiment of the present invention, the pH adjuster contained in the polishing composition is 90% by mass or more, 95% by mass or more, 98% by mass or more, 99% by mass or more, 99.5% by mass or more, or 99.9% by mass or more (upper limit: 100% by mass). According to one embodiment of the present invention, the pH adjuster contained in the polishing composition is 90% by mass or more, 95% by mass or more, 98% by mass or more, 99% by mass or more, 99.5% by mass or more, or 99.9% by mass or more (upper limit: 100% by mass). Note that even if abrasive grains (particularly colloidal silica), polymeric compounds having amide bonds, and optionally contained preservatives have the function of slightly changing the pH of the polishing composition, their ability to change the pH is low, and therefore, in the present invention, they may not be included in the category of pH adjusters in this specification.

[0031] [Polymer compounds containing amide bonds] A polishing composition according to one embodiment of the present invention contains a polymeric compound having an amide bond. This composition allows the polishing composition to control the selectivity while suppressing the number of PIDs after polishing. Here, the amide bond is a bond between a carbonyl group and nitrogen. The polymeric compound having an amide bond may have a cyclic amide structure such as polyvinylpyrrolidone, or may have an acyclic amide structure such as polyacrylamide or poly-N-vinylacetamide.

[0032] According to one embodiment of the present invention, the polymeric compound having an amide bond may be a nonionic polymer. According to one embodiment of the present invention, the polymeric compound having an amide bond is a water-soluble polymer. According to one embodiment of the present invention, when the water-soluble polymer is dissolved in water to a concentration of 0.5% by mass at the temperature at which the water-soluble polymer is most soluble, the mass of insoluble matter filtered out when filtered through a G2 glass filter (maximum pore size 40-50 μm) is within 50% by mass of the water-soluble polymer added. According to one embodiment of the present invention, "water-soluble" means that the solubility in water (25°C) is 1 g / 100 mL or more, and "polymer" refers to a (co)polymer having a repeating unit in its molecular structure and a weight-average molecular weight (Mw) of 1,000 or more.

[0033] According to one embodiment of the present invention, the polymer compound having an amide bond may be a homopolymer consisting of a repeating unit having an amide bond, a copolymer consisting of a repeating unit having an amide bond, or a copolymer having a repeating unit having an amide bond and a repeating unit not having an amide bond. When the polymer compound having an amide bond is a copolymer, it may be any of a block copolymer, a random copolymer, a graft copolymer, and an alternating copolymer.

[0034] According to one embodiment of the present invention, the polymer compound having an amide bond may have a nitrogen atom in the main chain or in the side chain. Examples of polymers containing a nitrogen atom in the main chain include homopolymers or copolymers of N-acylalkyleneimine monomers such as N-acetylethyleneimine and N-propionylethyleneimine. Examples of polymers containing a nitrogen atom in the side chain include homopolymers or copolymers containing repeating units derived from N-vinyl monomers such as N-vinyl lactams or N-vinyl linear amides, and homopolymers or copolymers containing repeating units derived from α,β-unsaturated amide monomers (monomers in which the main chain and side chain are bonded via a carbon atom) such as acrylamide.

[0035] According to one embodiment of the present invention, the polymer compound having an amide bond is represented by the following formula (1):

[0036] [ka]

[0037] In the above formula (1), A is a group selected from at least one of the following:

[0038] [ka]

[0039] m is an integer from 1 to 5, and R 1 ~R 4 are each independently selected from a hydrogen atom and an alkyl group having 1 to 4 carbon atoms, 1 and R 2 may form a ring, and when forming a ring, may contain at least one oxygen atom; R 3 and R 4may form a ring, and when a ring is formed, it may contain at least one oxygen atom, and in Formula 1-1, at least one oxygen atom may be contained in the ring. Here, * indicates the bonding point. The number of oxygen atoms contained in the ring is each independently 1 or 2, for example.

[0040] In one embodiment of the present invention, R 1 and R 2 are each independently selected from a hydrogen atom and an alkyl group having 1 to 4 carbon atoms. In one embodiment of the present invention, R 3 and R 4 are each independently selected from a hydrogen atom and an alkyl group having 1 to 4 carbon atoms.

[0041] In one embodiment of the present invention, m is 2, 3 or 4.

[0042] In one embodiment of the present invention, R 1 ~R 4 The number of carbon atoms in the alkyl group is 1 to 3, or 1 or 2. In one embodiment of the present invention, the alkyl group having 1 to 4 carbon atoms is, for example, a methyl group, an ethyl group, a propyl group, an i-propyl group, a butyl group, or a t-butyl group.

[0043] In one embodiment of the present invention, R 1 and R 2 At least one of the groups is a hydrogen atom.

[0044] In one embodiment of the present invention, R 3 and R 4 One of the groups is a hydrogen atom and the other is an alkyl group having 1 to 4 carbon atoms.

[0045] In one embodiment of the present invention, the polymer compound having an amide bond has repeating units in which A is at least one of formula (1-1), formula (1-2), and formula (1-3) in the polymer compound having an amide bond at 90 mol % or more, or 95 mol % or more (upper limit 100 mol %). In one embodiment of the present invention, the polymer compound having an amide bond has repeating units in which A is formula (1-1) in the polymer compound having an amide bond at 90 mol % or more, or 95 mol % or more (upper limit 100 mol %).

[0046] In one embodiment of the present invention, specific examples of N-vinyl lactams include N-vinylpyrrolidone (VP), N-vinylpiperidone, and N-vinylcaprolactam (VC). In one embodiment of the present invention, a suitable example of a polymer containing an N-vinyl lactam repeating unit is a vinylpyrrolidone-based polymer. Here, the vinylpyrrolidone-based polymer refers to a VP homopolymer or a VP copolymer (e.g., a copolymer in which the copolymerization ratio of VP exceeds 20 mol%). In the vinylpyrrolidone-based polymer, the proportion of the number of moles of VP units to the number of moles of all repeating units is suitably 20 mol% or more, 25 mol% or more, 30 mol% or more, 50 mol% or more, 80 mol% or more, 90 mol% or more, or 95 mol% or more (upper limit: 100 mol%).

[0047] In one embodiment of the present invention, specific examples of N-vinyl chain amides include N-vinylacetamide, N-vinylpropionamide, and N-vinylbutyric acid amide. In one embodiment of the present invention, suitable examples of polymers containing N-vinyl chain amide repeating units include vinylacetamide-based polymers. Here, the vinylacetamide-based polymer refers to a vinylacetamide homopolymer or a vinylacetamide copolymer (e.g., a copolymer in which the copolymerization ratio of vinylacetamide exceeds 50 mol%). In vinylacetamide-based polymers, the proportion of the number of moles of vinylacetamide units in the number of moles of all repeating units is usually 50 mol% or more, and suitably 80 mol% or more (e.g., 90 mol% or more, typically 95 mol% or more) (the upper limit is 100 mol%).

[0048] In one embodiment of the present invention, specific examples of α,β-unsaturated amide monomers include acryloylmorpholine, acrylamide, dimethylacrylamide, and N-isopropylacrylamide. In one embodiment of the present invention, a suitable example of a polymer derived from an α,β-unsaturated amide monomer is an acrylamide polymer. Here, an acrylamide polymer refers to an acrylamide homopolymer or an acrylamide copolymer (e.g., a copolymer in which the copolymerization ratio of acrylamide exceeds 50 mol%). In an acrylamide polymer, the proportion of the number of moles of acrylamide units to the number of moles of all repeating units is suitably 20 mol% or more, 25 mol% or more, 30 mol% or more, 50 mol% or more, 80 mol% or more, 90 mol% or more, or 95 mol% or more (upper limit: 100 mol%).

[0049] In one embodiment of the present invention, the polymer compound having an amide bond may be polyvinylpyrrolidone, polyacrylamide, or poly-N-vinylacetamide. Among them, polyvinylpyrrolidone is preferable from the viewpoint of suppressing the number of PIDs after polishing while controlling the selectivity.

[0050] In one embodiment of the present invention, the weight-average molecular weight of the polymer compound having an amide bond is 1,000 or more, 2,000 or more, 4,000 or more, 6,000 or more, 8,000 or more, more than 8,000, 10,000 or more, 20,000 or more, 40,000 or more, 43,000 or more, 47,000 or more, 60,000 or more, 90,000 or more, 120,000 or more, 160,000 or more, or 200,000 or more. In one embodiment of the present invention, the weight-average molecular weight of the polymer compound having an amide bond is 2,000,000 or less, 1,000,000 or less, 500,000 or less, 400,000 or less, 300,000 or less, less than 250,000, 250,000 or less, 100,000 or less, 80,000 or less, 70,000 or less, 60,000 or less, 50,000 or less, 40,000 or less, 30,000 or less, 20,000 or less, or 10,000 or less. In one embodiment of the present invention, the weight-average molecular weight of the polymer compound having an amide bond is more than 8,000 and 250,000 or less. Within this range, the selectivity can be controlled while the effect of suppressing the number of PIDs after polishing is significant.

[0051] In one embodiment of the present invention, the mass concentration of the polymer compound having an amide bond in the object to be polished is 1 mass ppm or more, 2 mass ppm or more, 4 mass ppm or more, 6 mass ppm or more, 8 mass ppm or more, 10 mass ppm or more, more than 10 mass ppm, 15 mass ppm or more, 20 mass ppm or more, 15 mass ppm or more, 20 mass ppm or more, 25 mass ppm or more, 30 mass ppm or more, 35 mass ppm or more, 40 mass ppm or more, 60 mass ppm or more, or 80 mass ppm or more. In one embodiment of the present invention, the mass concentration of the polymer compound having an amide bond in the polishing target is 1,000 ppm by mass or less, 800 ppm by mass or less, 600 ppm by mass or less, 400 ppm by mass or less, 200 ppm by mass or less, 100 ppm by mass or less, less than 100 ppm by mass, 80 ppm by mass or less, 60 ppm by mass or less, 50 ppm by mass or less, 40 ppm by mass or less, 30 ppm by mass or less, 20 ppm by mass or less, or 15 ppm by mass or less. In one embodiment of the present invention, the mass concentration of the polymer compound having an amide bond in the polishing target is more than 10 ppm by mass and less than 100 ppm by mass. Within this range, the effect of suppressing the number of PIDs after polishing while controlling the selectivity is remarkable.

[0052] [pH] The pH of the polishing composition of one embodiment of the present invention is 9.0 to 11.5. If the pH of the polishing composition is less than 9.0 or more than 11.5, the effects of controlling the selectivity and suppressing the number of PIDs after polishing may not be achieved.

[0053] According to one embodiment of the present invention, the pH of the polishing composition is 9.1 or more, 9.2 or more, 9.3 or more, 9.4 or more, 9.5 or more, more than 9.5, 9.6 or more, 9.7 or more, 9.8 or more, 9.9 or more, or 10.5 or more. According to one embodiment of the present invention, the pH of the polishing composition is 11.5 or less, 11.4 or less, 11.3 or less, 11.2 or less, less than 11.2, 11.1 or less, 11 or less, less than 11, 10.9 or less, 10.8 or less, 10.7 or less, 10.6 or less, 10.5 or less, 10.4 or less, 10.3 or less, 10.2 or less, 10.1 or less, or 9.8 or less.

[0054] According to one embodiment of the present invention, the pH of the polishing composition is greater than 10.0 and less than 11.2. Within this range, the effect of suppressing the number of PIDs after polishing is more pronounced while controlling the selectivity.

[0055] According to one embodiment of the present invention, the pH of the polishing composition is not 9.1, 9.2, 9.3, 9.4, 9.6, 9.7, 9.8, 9.9, 10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.9, 11.1, 11.3, 11.4, or 11.5. The pH of the polishing composition is measured by the method described in the Examples.

[0056] [Polished object] According to one embodiment of the present invention, a polishing composition is used in a step of polishing a first layer having a recess and a second layer formed to fill the recess, thereby exposing the first layer. FIG. 1 is a schematic cross-sectional view of the object to be polished (before polishing). As shown in the upper diagram of FIG. 1, a first layer 1 (a film having oxygen-silicon bonds or nitrogen-silicon bonds) is formed on an arbitrary film (e.g., a Si substrate) so as to form a recess. Then, as shown in the lower diagram of FIG. 1, a second layer 2 (a film having silicon-silicon bonds) is formed so as to fill the recess, thereby forming an object to be polished 10 including the first layer and the second layer.

[0057] According to one embodiment of the present invention, when the polishing composition of the present invention is applied, as shown in FIG. 2, the polished object 10', which is the object to be polished after polishing, can have an ideal polished surface in which the remaining material to be polished (film having silicon-silicon bonds) is reduced (no remaining material) and / or recesses are suppressed (no recesses are generated). Furthermore, by applying the polishing composition of the present invention, the number of metal atoms that may remain after polishing can also be reduced. According to one embodiment of the present invention, when the polished object 10' is polished to a thickness of 1 cm, the remaining material to be polished (film having silicon-silicon bonds) is reduced (no remaining material) and / or recesses are suppressed (no recesses are generated), the polished object 10' can have an ideal polished surface. 2 The number of remaining metal atoms per unit (unit: × 10 10 pieces / cm 2) is less than 40, less than 38, less than 35, less than 30, less than 25, less than 24, less than 20, less than 19, or less than 17. According to one embodiment of the present invention, 2 The number of remaining metal atoms per unit (unit: × 10 10 pieces / cm 2 ) is, for example, 0, 0.01 or more, 0.5 or more, 1 or more, 5 or more, or 10 or more. FIG. 3 is a schematic cross-sectional view showing a recess 2a. FIG. 4 is a schematic cross-sectional view showing a remnant 2b of the object to be polished (a film having silicon-silicon bonds). FIG. 5 is a schematic cross-sectional view showing a recess 2a and a remnant 2b of the object to be polished (a film having silicon-silicon bonds) simultaneously.

[0058] In one embodiment of the present invention, the polishing target having an oxygen-silicon bond may be TEOS-type silicon oxide (hereinafter simply referred to as "TEOS") produced using tetraethyl orthosilicate as a precursor, HDP (High Density Plasma), USG (Undoped Silicate Glass), PSG (Phosphorus Silicate Glass), BPSG (Boron-Phospho Silicate Glass), or RTO (Rapid Thermal Oxidation). The TEOS film may be formed by plasma CVD.

[0059] In one embodiment of the present invention, examples of the polishing object having a nitrogen-silicon bond include a silicon nitride film or SiCN (silicon carbonitride). As a material for the stopper film, it is preferable that the first layer contains an object to be polished having a nitrogen-silicon bond. In one embodiment of the present invention, examples of the polishing object having a silicon-silicon bond include polysilicon, amorphous silicon, single crystal silicon, n-type doped single crystal silicon, p-type doped single crystal silicon, and Si-based alloys such as SiGe. Among these, it is preferable that the second layer be polycrystalline silicon such as polysilicon.

[0060] [Polishing speed] According to one embodiment of the present invention, the polishing composition has physical properties that result in a removal rate of the second layer of 1500 Å / min or more, 1600 Å / min or more, 1700 Å / min or more, 1800 Å / min or more, 1900 Å / min or more, or 2000 Å / min or more. According to one embodiment of the present invention, the polishing composition has physical properties that result in a removal rate of the second layer of 3500 Å / min or less, or 3200 Å / min or less.

[0061] According to one embodiment of the present invention, when the first layer has an oxygen-silicon bond, the polishing composition has physical properties that result in a removal rate of the first layer of 45 Å / min or more, 50 Å / min or more, 60 Å / min or more, 70 Å / min or more, 80 Å / min or more, or 90 Å / min or more. According to one embodiment of the present invention, when the first layer has an oxygen-silicon bond, the polishing composition has physical properties that result in a removal rate of the first layer of 180 Å / min or less, 160 Å / min or less, 140 Å / min or less, 120 Å / min or less, 100 Å / min or less, or 95 Å / min or less.

[0062] According to one embodiment of the present invention, when the first layer has a nitrogen-silicon bond, the polishing composition has physical properties that result in a removal rate of the first layer of 14 Å / min or more, 16 Å / min or more, 18 Å / min or more, 20 Å / min or more, 22 Å / min or more, 24 Å / min or more, or 26 Å / min or more. According to one embodiment of the present invention, when the first layer has a nitrogen-silicon bond, the polishing composition has physical properties that result in a removal rate of the first layer of 50 Å / min or less, 40 Å / min or less, 30 Å / min or less, 28 Å / min or less, or 26 Å / min or less.

[0063] [Selection ratio] According to one embodiment of the present invention, the polishing composition has physical properties such that the polishing rate (selectivity) of the second layer relative to the polishing rate of the first layer is 17 to 40, or 20 to 40, when the first layer has an oxygen-silicon bond.

[0064] According to one embodiment of the present invention, when the first layer has a nitrogen-silicon bond, the polishing composition has physical properties such that the polishing rate of the second layer relative to the polishing rate of the first layer (selectivity ratio) is greater than 40 and not more than 100, 45 to 95, 50 to 90, 55 to 85, or 60 to 80.

[0065] According to one embodiment of the present invention, when the first layer has an oxygen-silicon bond, the polishing composition has physical properties such that the selectivity is 17 or more, 18 or more, 19 or more, 20 or more, 21 or more, 22 or more, 23 or more, 24 or more, 25 or more, 26 or more, 27 or more, 28 or more, 29 or more, 30 or more, 31 or more, 32 or more, 33 or more, 34 or more, or 35 or more. According to one embodiment of the present invention, when the first layer has an oxygen-silicon bond, the polishing composition has physical properties such that the selectivity is 39 or less, 37 or less, 35 or less, 33 or less, 31 or less, or 29 or less.

[0066] According to one embodiment of the present invention, when the first layer has a nitrogen-silicon bond, the polishing composition has physical properties such that the selectivity is 45 or more, 50 or more, 55 or more, 60 or more, 65 or more, or 70 or more. According to one embodiment of the present invention, when the first layer has a nitrogen-silicon bond, the polishing composition has physical properties such that the selectivity is 100 or less, 95 or less, 90 or less, 85 or less, 80 or less, 75 or less, or 70 or less.

[0067] [Transmittance] According to one embodiment of the present invention, when the concentration of abrasive grains (particularly colloidal silica) contained in the polishing composition is 1.5 mass %, the transmittance of light with a wavelength of 450 nm transmitted through the polishing composition is more than 0.1% and less than 1%. The polishing composition of this embodiment contributes to suppressing the number of PIDs after polishing. Methods for adjusting the transmittance within the above range include, for example, adjusting the particle size of the colloidal silica and adjusting the electrical conductivity.

[0068] According to one embodiment of the present invention, the transmittance is 0.13% or more, or 0.5% or more, and according to one embodiment of the present invention, the transmittance is 0.9% or less, 0.7% or less, 0.5% or less, or 0.3% or less.

[0069] Here, when the abrasive concentration of the polishing composition is not 1.5% by mass, the abrasive concentration can be adjusted to 1.5% by mass as follows. That is, when the abrasive concentration of the polishing composition is more than 1.5% by mass, an appropriate amount of water can be added so that the abrasive concentration becomes 1.5% by mass. When the abrasive concentration of the polishing composition is less than 1.5% by mass, the polishing composition can be stored in an environment of 25 to 40°C until the abrasive concentration reaches 1.5% by mass, or a process such as ultrafiltration can be performed.

[0070] [water] The polishing composition of one embodiment of the present invention contains water as an aqueous carrier. According to one embodiment of the present invention, the aqueous carrier may contain, but is not limited to, alcohols such as methanol, ethanol, and ethylene glycol; ketones such as acetone; etc., but the water content of the aqueous carrier is 90 mass % or more, 95 mass % or more, 98 mass % or more, 99 mass % or more, 99.5 mass % or more, or 99.9 mass % or more (upper limit: 100 mass %).

[0071] [Preservatives] According to one embodiment of the present invention, the polishing composition contains a preservative. Examples of preservatives include isothiazolinone preservatives such as 2-methyl-4-isothiazolin-3-one, 5-chloro-2-methyl-4-isothiazolin-3-one, and 1,2-benzisothiazol-3(2H)-one (BIT), parahydroxybenzoic acid ester preservatives such as methyl parahydroxybenzoate and ethyl parahydroxybenzoate, and phenoxyethanol. These preservatives may be used alone or in combination of two or more.

[0072] According to one embodiment of the present invention, the polishing composition may contain 0.001 to 1 mass %, 0.005 to 0.5 mass %, or 0.01 to 0.1 mass % of a preservative.

[0073] According to one embodiment of the present invention, the number of silanol groups is 6 / nm 2 More than 22 pieces / nm 2 Provided is a polishing composition that essentially consists of the following colloidal silica, an alkali metal salt, a polymeric compound having an amide bond, a preservative, and water, and has a pH of 9.0 to 11.5. The above explanations for the colloidal silica, the alkali metal salt, the polymeric compound having an amide bond, the water, the pH, and the preservative are applicable. The phrase "essentially consists" will be explained later.

[0074] [Other ingredients] According to one embodiment of the present invention, the polishing composition is substantially free of at least one of a surfactant, an oxidizing agent, and a compound having a nitrogen atom (excluding a polymeric compound having an amide bond). Here, "substantially free" means that the amount of the component in question in the polishing composition is 0.1% by mass or less, 0.01% by mass or less, 0.001% by mass or less, or less than 0.0001% by mass, unless otherwise specified.

[0075] A surfactant is a substance having a hydrophilic group and a hydrophobic group. Examples of such surfactants include alkyl ether types such as polyoxyethylene lauryl ether and polyoxyethylene oleyl ether, alkyl phenyl ether types such as polyoxyethylene octylphenyl ether, alkyl ester types such as polyoxyethylene laurate, alkyl amine types such as polyoxyethylene lauryl amino ether, alkyl amide types such as polyoxyethylene lauric acid amide, polypropylene glycol ether types such as polyoxyethylene polyoxypropylene ether, alkanolamide types such as oleic acid diethanolamide, and allyl phenyl ether types such as polyoxyalkylene allyl phenyl ether. Other examples include nonionic surfactants such as propylene glycol, diethylene glycol, monoethanolamine, alcohol ethoxylates, alkylphenol ethoxylates, tertiary acetylene glycols, and alkanolamides; anionic surfactants such as carboxylic acid types such as sodium myristate, sodium palmitate, sodium stearate, sodium laurate, and potassium laurate; sulfate ester types such as sodium octyl sulfate; phosphate ester types such as lauryl phosphoric acid and sodium lauryl phosphate; and sulfonic acid types such as dioctyl sodium sulfosuccinate and sodium dodecylbenzenesulfonate; cationic surfactants such as amines such as laurylamine hydrochloride; and benign surfactants such as alkyl betaines and sulfobetaines, including lecithin, alkylamine oxides, and N-alkyl-N,N-dimethylammonium betaines. According to one embodiment of the present invention, the polishing composition is substantially free of at least one of these surfactants.

[0076] The oxidizing agent may be a substance having a higher redox potential than the redox potential of the substrate material (particularly polysilicon) at the pH at which polishing is performed. The pH at which polishing is performed is typically the same as the pH of the polishing composition. The redox potential of the substrate material may be determined by dispersing powder of the material (particularly polysilicon) in water to form a slurry, adjusting the slurry to the same pH as the polishing composition, and then measuring the redox potential of the slurry (the redox potential relative to a standard hydrogen electrode at a liquid temperature of 25°C) using a commercially available redox potentiometer. Examples of the oxidizing agent include hydrogen peroxide, metal oxides, peroxides, nitrates, iodates, periodates, hypochlorites, chlorites, chlorates, perchlorates, persulfates, dichromates, permanganates, organic oxidizing agents, ozone water, silver(II) salts, iron(III) salts, and the like. According to one embodiment of the present invention, the polishing composition is substantially free of at least one of these.

[0077] Examples of compounds containing nitrogen atoms include hydroxides such as tetramethylammonium, tetraethylammonium, and tetrabutylammonium, as well as salts such as chlorides, carbonates, sulfates, and phosphates. Specific examples include quaternary ammonium compounds such as tetraalkylammonium hydroxides such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, and tetrabutylammonium hydroxide; tetraalkylammonium hydroxide salts such as tetramethylammonium carbonate and tetramethylammonium chloride; amines such as methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, ethylenediamine, monoethanolamine, N-(β-aminoethyl)ethanolamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, anhydrous piperazine, piperazine hexahydrate, 1-(2-aminoethyl)piperazine, N-methylpiperazine, and guanidine; and ammonia. According to one embodiment of the present invention, the polishing composition is substantially free of at least one of these compounds. According to one embodiment of the present invention, the polishing composition contains less than 0.05% by mass of tetraalkylammonium salts.

[0078] According to one embodiment of the present invention, the polishing composition is substantially free of abrasive grains other than colloidal silica.

[0079] According to one embodiment of the present invention, the polishing composition is substantially free of silica having acidic groups (for example, sulfo groups, carboxyl groups, phosphate groups, etc.) derived from organic acids fixed to the surface.

[0080] According to one embodiment of the present invention, the polishing composition is substantially free of silica having amino groups fixed to the surface thereof.

[0081] According to one embodiment of the present invention, the polishing composition is substantially free of organic acids.

[0082] According to one embodiment of the present invention, the polishing composition comprises R 1 R 2 R 3 R 4 N + X - , R 1 R 2 R 3 R 4 P + X - , R 1 R 2 R 3 S + X - , imidazolium salts, and pyridinium salts, where R 1 , R 2 , R 3 , and R 4 each independently represents C1 to C6 alkyl, C7 to C 12 Aryl alkyl or C6-C 10 aryl, and X -or an anion. The reason is that when a cationic agent having such a hydrophobic portion is adsorbed onto the surface of colloidal silica, the surface of the colloidal silica becomes hydrophobic, making it difficult for the colloidal silica to separate from the highly water-repellent object to be polished (particularly polysilicon), which may make the colloidal silica more likely to remain as residue and cause PID. In other words, this embodiment can suppress the number of PIDs after polishing.

[0083] According to one embodiment of the present invention, the polishing composition does not contain any of hydroxyalkyl cellulose, carrageenan, and xanthan gum. By using such an embodiment, the number of PIDs after polishing can be suppressed.

[0084] According to one embodiment of the present invention, the polishing composition is substantially free of phosphate esters. In this specification, the term "substantially free of phosphate esters" means that the polishing composition does not contain any phosphate esters (below the detection limit), or may contain less than 0.001 mass% of phosphate esters in the polishing composition.

[0085] In one embodiment of the present invention, the number of silanol groups is 6 / nm 2 More than 22 pieces / nm 2 Provided is a polishing composition that consists essentially of the following colloidal silica, an alkali metal salt, a polymeric compound having an amide bond (particularly PVP), and water, and has a pH of 9.0 to 11.5. The above explanations regarding colloidal silica, alkali metal salt, polymeric compound having an amide bond, water, and pH can be applied. "Substantially consists" means that when the polishing composition contains components other than colloidal silica, alkali metal salt (particularly potassium hydroxide), polymeric compound having an amide bond (particularly PVP), water, and an optionally contained preservative, the proportion of these components (the total of these components) in the polishing composition is 0.1% by mass or less, 0.01% by mass or less, 0.001% by mass or less, or less than 0.0001% by mass.

[0086] In one embodiment of the present invention, the polishing composition may be a one-component type or a multi-component type, such as a two-component type. Furthermore, the polishing composition of one aspect of the present invention may be used as a polishing liquid after dilution (typically with water), or may be used as a polishing liquid as is. That is, the concept of the polishing composition in the technology according to the present invention encompasses both a polishing composition (working slurry) that is supplied to an object to be polished and used to polish the object, and a concentrated liquid (raw solution of working slurry) that is diluted and used for polishing. The concentration ratio of the concentrated liquid can be, for example, about 2 to 100 times on a volume basis.

[0087] <Method for producing polishing composition> In one embodiment of the present invention, a method for producing a polishing composition includes adjusting the pH to 9.0 to 11.5 by adding colloidal silica, an alkali metal salt (particularly potassium hydroxide), a polymeric compound having an amide bond (particularly PVP), water, and an optional preservative. The above explanations regarding the colloidal silica, the alkali metal salt (particularly potassium hydroxide), the polymeric compound having an amide bond (particularly PVP), water, pH, and the preservative are applicable. The temperature at which the components are mixed is not particularly limited, but is preferably 10°C to 40°C, and heating may be used to increase the dissolution rate. The mixing time is also not particularly limited as long as uniform mixing is achieved.

[0088] <Method for polishing the object to be polished> In one embodiment of the present invention, a method for polishing an object to be polished includes, as shown in FIG. 1 , a step of polishing second layer 2 to expose first layer 1 in an object to be polished 10 having a first layer 1 (a layer having oxygen-silicon bonds or nitrogen-silicon bonds) with a recess formed therein and a second layer 2 (a layer having silicon-silicon bonds) formed to fill the recess. In one embodiment of the present invention, the method further includes a step of polishing the first layer after the first layer is exposed. Including such a step has the technical effect of completely removing any remaining material, such as polysilicon, from the object to be polished.

[0089] In one embodiment of the present invention, as shown in Figure 1, a first layer 1 (a layer having oxygen-silicon bonds or a layer having nitrogen-silicon bonds) is formed on any film (e.g., a Si substrate) so as to provide a recess. A second layer 2 (a film having silicon-silicon bonds) is then formed to fill the recess, and an excess amount of the second layer 2 is deposited so as to protrude from the recess of the first layer 1, thereby forming an object to be polished 10 including the first layer 1 and the second layer 2. Such an object to be polished 10 is polished using a polishing apparatus capable of supplying the polishing composition of the present invention.

[0090] In one embodiment of the present invention, the polishing apparatus can be a general polishing apparatus equipped with a holder for holding a substrate or the like having an object to be polished, a motor capable of changing the rotation speed, and a polishing platen onto which a polishing pad (polishing cloth) can be attached.

[0091] In one embodiment of the present invention, the polishing pad can be made of any material, including general nonwoven fabric, polyurethane, porous fluororesin, etc. It is preferable that the polishing pad has grooves formed therein so that the polishing liquid can be collected.

[0092] In one embodiment of the present invention, the polishing conditions are, for example, preferably 10 to 500 rpm for the rotation speed of the polishing platen and the carrier, each independently. The pressure (polishing pressure) applied to the substrate carrying the object to be polished is preferably 0.5 to 10 psi. The method for supplying the polishing composition to the polishing pad is not particularly limited, and for example, a method of continuously supplying the composition using a pump or the like is used. There is no limit to the amount of supply, but it is preferable that the surface of the polishing pad is always covered with the polishing composition of the present invention.

[0093] In one embodiment of the present invention, by applying the polishing composition of the present invention, as shown in Figure 2, the polished object 10', which is the object to be polished after polishing, can have an ideal polished surface in which the amount of remaining material to be polished is reduced (no remaining material) and / or recesses are suppressed (no recesses occur). [Example]

[0094] The present invention will be described in more detail using the following examples and comparative examples. However, the technical scope of the present invention is not limited to the following examples. In the following, unless otherwise specified, the operations were carried out under the conditions of room temperature (25°C) and relative humidity of 40 to 50% RH.

[0095] <Production of Polishing Composition> Polishing compositions were prepared by mixing abrasive grains, an alkali metal salt, a polymer compound, and water to obtain the compositions shown in Table 1. For example, the polishing composition of Example 1 had a pulse NMR specific surface area of ​​23.8 m 2 / g, 7.9 silanol groups / nm 2 The composition contains 1.5 mass% colloidal silica having an average primary particle size of 90 nm and an average secondary particle size of 220 nm, potassium hydroxide, water, and 40 mass ppm of polyvinylpyrrolidone (PVP) (weight average molecular weight 8,000), and has a pH of 10.8.

[0096] [Weight average molecular weight] In this specification, the "weight average molecular weight" can refer to the weight average molecular weight (in terms of polyethylene glycol) measured by gel permeation chromatography (GPC). The weight average molecular weight can be measured using the following apparatus and conditions: GPC equipment: Shimadzu Corporation Model: Prominence + ELSD detector (ELSD-LTII) Column: VP-ODS (Shimadzu Corporation) Mobile phase A:MeOH B: 1% aqueous solution of acetic acid Flow rate: 1mL / min Detector: ELSD temp. 40℃, Gain 8, N2GAS 350kPa Oven temperature: 40°C Injection volume: 40μL.

[0097] <Calculation method for particle size> The average primary particle size of the abrasive grains was calculated from the specific surface area of ​​the abrasive grains measured by the BET method using a "MacsorbHM model-1210" manufactured by Mountech Co., Ltd., and the density of the abrasive grains.

[0098] The average secondary particle size of the abrasive grains was measured using a dynamic light scattering particle size distribution analyzer UPA-UT151 manufactured by Nikkiso Co., Ltd.

[0099] <Method for measuring specific surface area using pulsed NMR> Each abrasive grain (colloidal silica) was dispersed in water to a concentration of 20% by mass to prepare a dispersion sample. The specific surface area was measured under the following measurement conditions using a pulsed NMR particle interface characterization device (manufactured by Xigo Nanotools), and the results are shown in Table 1.

[0100] [Measurement conditions] Bulk relaxation time: 2409ms Specific surface relaxivity:0.00026 Volume ratio of particles to liquid:0.1136.

[0101] <How to calculate the number of silanol groups> The number of silanol groups per unit surface area of ​​the abrasive grain (unit: pieces / nm 2 ) was calculated by the following method after measuring or calculating each parameter by the following measurement method or calculation method.

[0102] More specifically, C in the following formula is the total mass of the abrasive grains, and S in the following formula is the BET specific surface area of ​​the abrasive grains. More specifically, first, 1.50 g of abrasive grains (solid content) was placed in a 200 ml beaker, and 100 ml of pure water was added to form a slurry. Then, 30 g of sodium chloride was added and dissolved. Next, 1 N hydrochloric acid was added to adjust the pH of the slurry to 3.0-3.5, and pure water was added until the slurry reached 150 ml.

[0103] Using an automatic titrator (COM-1700, manufactured by Hiranuma Sangyo Co., Ltd.), the pH of this slurry was adjusted to 4.0 with 0.1 N sodium hydroxide at 25°C, and the volume V [L] of 0.1 N sodium hydroxide solution required to raise the pH from 4.0 to 9.0 by pH titration was measured. The average silanol group density (number of silanol groups) can be calculated using the following formula.

[0104] ρ=(c×V×N A ) / (C×S) In the above formula, ρ is the average silanol group density (number of silanol groups) (number / nm 2 ) represents; c represents the concentration (mol / L) of the sodium hydroxide solution used in the titration; V represents the volume (L) of sodium hydroxide solution required to raise the pH from 4.0 to 9.0; N A represents the Avogadro constant (units / mol); C represents the total mass (solid content) of the abrasive grains (g); S is the weighted average value of the BET specific surface area of ​​the abrasive grains (nm 2 The BET specific surface area is the value of the specific surface area of ​​the abrasive grain measured by the BET method using a "MacsorbHM model-1210" manufactured by Mountech Co., Ltd.

[0105] <Measurement of pH of polishing composition> A glass electrode hydrogen ion concentration indicator (model number: F-23, manufactured by Horiba, Ltd.) was used, and three-point calibration was performed using standard buffer solutions (phthalate pH buffer solution pH: 4.01 (25°C), neutral phosphate pH buffer solution pH: 6.86 (25°C), carbonate pH buffer solution pH: 10.01 (25°C)).The glass electrode was then placed in the polishing composition, and the value after stabilization for more than two minutes was measured as the pH of the polishing composition.

[0106] <Measurement of transmittance of polishing composition> The transmittance of the polishing composition was measured by irradiating the polishing composition with light having a wavelength of 450 nm using an ultraviolet-visible spectrophotometer (UV-2450, manufactured by Shimadzu Corporation). The results are shown in Table 1.

[0107] <Measurement of polishing speed> The polishing composition was used to polish the surfaces of the objects to be polished under the following polishing conditions: a silicon wafer (300 mm, blanket wafer) with a 5000 Å thick polysilicon (Poly-Si) film formed on its surface, a silicon wafer (300 mm, blanket wafer) with a 10000 Å thick P-TEOS film (TEOS film (silicon dioxide film) formed by plasma CVD) formed on its surface, and a silicon wafer (300 mm, blanket wafer) with a 3000 Å thick silicon nitride (SiN) film formed on its surface.

[0108] (polishing conditions) Polishing equipment: Applied Materials 300mm CMP single-sided polishing equipment Reflexion LK Pad: Nitta Haas Corporation hard polyurethane pad IC1010 Polishing pressure: 1.5 psi (1 psi = 6894.76 Pa, same below) Polishing platen rotation speed: 70 rpm Carrier rotation speed: 70 rpm Supply of polishing composition: free-flowing Polishing composition supply amount: 200ml / min Polishing time: 60 seconds.

[0109] [Condition 1] Polishing equipment: Applied Materials 300mm CMP single-sided polishing equipment Reflexion LK Pad: Nitta Haas IC1010 Hard Polyurethane Pad Polishing pressure: 1.5 psi (1 psi = 6894.76 Pa, same below) Polishing platen rotation speed: 70 rpm Carrier rotation speed: 70 rpm Supply of polishing composition: free-flowing Polishing composition supply amount: 200ml / min, Grinding time: 1 minute.

[0110] The polishing rate was determined by measuring the thickness using an optical film thickness meter (RE-3500, manufactured by SCREEN Co., Ltd.) and dividing (thickness before polishing) by (thickness after polishing) by the polishing time. The selectivity was calculated as the ratio of the polishing rate (Å / min) of the polysilicon film to the polishing rate (Å / min) of the P-TEOS film. The selectivity was also calculated as the ratio of the polishing rate (Å / min) of the polysilicon film to the polishing rate (Å / min) of the SiN film. The results are shown in Table 1.

[0111] <Polysilicon PID measurement> i) For the silicon wafers with a polished polysilicon (Poly-Si) film, a cleaning tank equipped with an ultrasonic oscillator was prepared, and a cleaning solution of 1:2 (volume ratio) of NH4OH (29%): HO (31%): deionized water (DIW) was placed in the cleaning tank and maintained at 50°C. The polished silicon wafers were immersed in the cleaning tank for 6 minutes and then rinsed with ultrapure water (SC-1 cleaning). The wafers were then immersed in a 2.5% HF aqueous solution for 30 seconds, followed by rinsing with ultrapure water to remove the surface oxide film formed by the SC-1 cleaning (HF cleaning).

[0112] ii) After SC-1 cleaning and HF cleaning, surface defects were detected on the surface of the polysilicon film using a wafer inspection device manufactured by KLA, product name "Surfscan SP5." The detected surface defects were analyzed using a defect review SEM (scanning electron microscope) manufactured by Hitachi High-Technologies Corporation, product name "Review-SEM RS6000," and the number of PIDs was counted.

[0113] <Metal impurity measurement (atomic number after cleaning)> The polished P-TEOS-coated silicon wafers were washed for 60 seconds using a PVA brush in the cleaning section while spraying deionized water (DIW). They were then dried for 30 seconds using a spin dryer. The concentrations of Na, K, and Li on the washed wafer surfaces were measured using a total reflection X-ray fluorescence spectrometer (TREX-610T) manufactured by Technos Corporation. The results are shown in Table 1.

[0114] <Desorption rate by water polishing> i) A silicon wafer (300 mm, blanket wafer) was prepared, on whose surface a polysilicon (Poly-Si) film with a thickness of 5000 Å was formed. 2 The native oxide film on the polysilicon film was removed by polishing with a 4 mass % aqueous dispersion of colloidal silica (average primary particle diameter: 35 nm, average secondary particle diameter: 70 nm, synthesized by the sol-gel method).

[0115] ii) The polysilicon film from which the native oxide film had been removed was polished under the above-mentioned [Condition 1] (except that the polishing time was changed to 30 seconds) using the polishing composition shown in Table 1. As a blank, a 5 μL droplet of deionized water (DIW) was dropped onto the polysilicon film from which the native oxide film had been removed, and the contact angle after 5 seconds was measured using a contact angle meter.

[0116] iii) Subsequently, the liquid supplied was changed from the polishing composition to deionized water (DIW) and water polishing was performed under Condition 1 (except that the polishing time was changed to 10 seconds). The contact angle of the polysilicon film subjected to water polishing was measured in the same manner as above. The desorption rate due to water polishing was calculated using the following formula.

[0117] (Desorption rate by water polishing) = (contact angle after 10 seconds of polishing - contact angle without water polishing) / (contact angle after removal of native oxide film - contact angle without water polishing) × 100 [%].

[0118] <Polysilicon recess evaluation> A patterned wafer with a polysilicon film was polished under the following [Condition 1] using the polishing composition listed in Table 1. As shown in Figure 1, the patterned wafer was prepared by laminating a SiN film (1000 Å) on a Si substrate, forming a recess by digging a trench 1000 Å deep, and then laminating a polysilicon film (2000 Å) so as to fill the recess. The width of the recess (isolated wiring portion) was 10 μm.

[0119] After the endpoint signal was detected, the polishing of the polysilicon film-coated patterned wafer was continued for a time equivalent to 40% of the polishing time until the endpoint signal was detected, and then the polishing was terminated. In this way, the process of further polishing the first layer (SiN film) after the first layer (SiN film) was exposed was realized.

[0120] The recess depth was measured in a 10 μm-wide isolated wiring portion on the surface of the patterned wafer using an atomic force microscope (product name: InSight CAP, manufactured by Bruker Corp.) The recess depth thus obtained was evaluated according to the following criteria.

[0121] [Recess amount] The recesses were evaluated according to the following four-level evaluation criteria. △× indicates that the recesses are not acceptable for practical use. The results are shown in Table 1.

[0122] ◎: Less than 50 nm ○: 50nm or more and less than 75nm △: 75nm or more and less than 100nm ×: 100 nm or more.

[0123] [Table 1]

[0124] <Consideration> The polishing compositions of the Examples were able to suppress the number of PIDs after polishing while controlling the selectivity. Comparing Example 3 with Examples 1 and 5 reveals that the molecular weight of the polymeric compound having an amide bond is preferably more than 8,000 and less than 250,000 in order to suppress the number of PIDs. Comparing Example 3 with Examples 2 and 4 reveals that the mass concentration of the polymeric compound having an amide bond in the polishing composition is preferably more than 10 ppm and less than 100 ppm in order to suppress the number of PIDs. Comparing Example 3 with Examples 6 and 7 reveals that, among polymeric compounds having an amide bond, polyvinylpyrrolidone is preferred in order to suppress the number of PIDs. Comparing Example 3 with Examples 8 and 9 reveals that the number of silanol groups in the colloidal silica is 6.6 / nm in order to suppress the number of PIDs. 2 Super 17.5 pieces / nm 2 It can be seen that it is preferable that the pH of the polishing composition is greater than 10.0 and less than 11.2 from the viewpoint of suppressing the number of PIDs. It can be seen that it is preferable that the pH of the polishing composition is greater than 10.0 and less than 11.2 from the viewpoint of suppressing the number of PIDs. It can be seen that it is preferable that the alkali metal salt is an alkali metal hydroxide rather than an alkali metal carbonate from the viewpoint of reducing the amount of residual metal. It can also be seen that it is particularly preferable that the alkali metal salt is potassium from the viewpoint of reducing the amount of residual metal.

[0125] In contrast, the polishing compositions of the comparative examples could control the selectivity in some cases, but could not suppress the number of PIDs after polishing. More specifically, the results of Comparative Examples 2 to 10 show that the number of silanol groups in the colloidal silica was 6 / nm 2It can be seen that the number of PIDs increases when the silanol group count of colloidal silica is less than 22 / nm 2 It can be seen that the number of PIDs increases when the pH of the polishing composition is greater than 11.5. The results of Comparative Examples 11 and 12 show that even if a water-soluble polymer known in the art is used, if it is not in the category of a polymer compound having an amide bond, the number of PIDs increases. The results of Comparative Example 13 show that the number of PIDs increases when the pH of the polishing composition is less than 9.0. The results of Comparative Example 14 show that the number of PIDs increases when the pH of the polishing composition is greater than 11.5.

[0126] An interesting point can also be made from the results of the desorption rate after water polishing. Even though the desorption rates after water polishing in Comparative Examples 2 to 10, 13, and 14 were equivalent to those in the Examples (that is, even though the state of polysilicon could be restored to its original state by water polishing), it is clear that the suppression of the number of PIDs can only be achieved with the composition of the present invention. [Explanation of symbols]

[0127] 1 first layer, 2 second layer, 2a recess, 2b Remaining second layer to be polished 10. Object to be polished; 10' Polished object.

Claims

1. The solution contains colloidal silica, an alkali metal salt, and a polymer compound having an amide bond, and has a pH of 9.0 to 11.5; (i) A polishing object having a first layer provided with a recess and a second layer formed so as to fill the recess, the polishing method being used in a step of polishing the second layer to expose the first layer, the first layer being selected from those having an oxygen-silicon bond or a nitrogen-silicon bond, and the second layer having a silicon-silicon bond. and / or (ii) The number of silanol groups in the colloidal silica is 6 / nm ２ More than 22 pieces / nm ２ A polishing composition comprising:

2. The polymer compound having an amide bond is represented by the following formula (1): 【Chemistry 1】 In the above formula (1), A is a group selected from at least one of the following: 【Chemistry 2】 m is an integer from 1 to 5, and R １ ~R ４ are each independently selected from a hydrogen atom and an alkyl group having 1 to 4 carbon atoms, １ and R ２ may form a ring, and when a ring is formed, it may contain at least one oxygen atom; R ３ and R ４ may form a ring, and when a ring is formed, may contain at least one oxygen atom, and in Formula 1-1, may contain at least one oxygen atom in the ring.

3. 2. The polishing composition according to claim 1, wherein when the first layer has an oxygen-silicon bond, the polishing rate of the second layer relative to the polishing rate of the first layer is 20 to 40.

4. 2. The polishing composition according to claim 1, wherein the polishing rate of the second layer relative to the polishing rate of the first layer is more than 40 and 100 or less when the first layer has a nitrogen-silicon bond.

5. The colloidal silica has a pulse NMR specific surface area of ​​40 m ２ The polishing composition according to claim 1, wherein the polishing composition has a viscosity of 1 / g or less.

6. 2. The polishing composition according to claim 1, wherein the average primary particle size of the colloidal silica is more than 70 nm and less than 100 nm.

7. 2. The polishing composition according to claim 1, wherein the alkali metal salt is an alkali metal hydroxide.

8. 8. The polishing composition according to claim 7, wherein the alkali metal hydroxide is potassium hydroxide.

9. 2. The polishing composition according to claim 1, wherein when the concentration of the colloidal silica is 1.5 mass %, the transmittance when light with a wavelength of 450 nm is transmitted is more than 0.1% and less than 1%.

10. 6 silanol groups / nm ２ More than 22 pieces / nm ２ A polishing composition consisting essentially of the following colloidal silica, an alkali metal salt, a polymer compound having an amide bond, and water, and having a pH of 9.0 to 11.

5.

11. 6 silanol groups / nm ２ More than 22 pieces / nm ２ A polishing composition substantially consisting of the following colloidal silica, an alkali metal salt, a preservative, a polymer compound having an amide bond, and water, and having a pH of 9.0 to 11.5.

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