Polishing composition

Abstract

To provide a new polishing composition capable of solving a trade-off problem that a ratio of a polishing speed of a film having a silicon-silicon bond such as polysilicon to a polishing speed of an insulating film such as a film having an oxygen-silicon bond is increased while removing a natural oxide film of the film having the silicon-silicon bond such as polysilicon to achieve more reliable insulating film stop and to suppress an insulating film loss.SOLUTION: The polishing composition contains colloidal silica having 6 / nm2 or more and 22 / nm2 or less silanol groups, alkaline metal salts, polymer compounds having amide bonds, basic amino acids, and water.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] In the field of CMP, polishing is sometimes performed by arranging an insulating film, such as a film having oxygen-silicon bonds (e.g., a silicon dioxide film) having recesses and a film having silicon-silicon bonds (e.g., polysilicon) formed to fill the recesses, and using the insulating film, such as a film having oxygen-silicon bonds (e.g., silicon dioxide), as a stopper film. The selectivity, which is the ratio of the polishing rate of the film having silicon-silicon bonds to the polishing rate of the insulating film, such as a film having oxygen-silicon bonds, is used as an index of how easily a film having silicon-silicon bonds is polished relative to an insulating film, such as a film having oxygen-silicon bonds. For the insulating film having oxygen-silicon bonds to function as a stopper layer, a high selectivity is desirable. For example, Patent Document 1 proposes a polishing composition that achieves a high selectivity and minimizes the occurrence of surface defects. The polishing composition comprises an abrasive, such as silicon dioxide, and water, and may further contain a basic organic compound, such as tetramethylammonium hydroxide. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 10-321569 Summary of the Invention [Problem to be solved by the invention]

[0004] As described above, in order to make an insulating film, such as a film having oxygen-silicon bonds such as silicon dioxide, which can be provided as an underlayer of a film having silicon-silicon bonds such as polysilicon, function as a stopper layer, a polishing composition is required that does not polish oxide films.

[0005] On the other hand, it is known that a film having silicon-silicon bonds, such as polysilicon, forms a natural oxide film when exposed to oxygen in the air, and in order to remove this, it is preferable that the polishing composition has the property of being able to polish the oxide film. However, when polishing is performed using such a polishing composition, the insulating film, such as a film having oxygen-silicon bonds, such as silicon dioxide, which serves as a stopper layer, is also polished away, resulting in so-called insulating film loss (sometimes called "oxide loss" when the insulating film is silicon dioxide).

[0006] Therefore, an object of the present invention is to provide a novel polishing composition that can remove the native oxide film of a film having silicon-silicon bonds such as polysilicon while increasing the ratio of the polishing rate of a film having silicon-silicon bonds such as polysilicon to the polishing rate of an insulating film such as a film having oxygen-silicon bonds, thereby realizing a more reliable insulating film stop and suppressing insulating film loss, thereby solving the trade-off problem of being able to remove the native oxide film of a film having silicon-silicon bonds such as polysilicon, while also increasing the ratio of the polishing rate of a film having silicon-silicon bonds such as polysilicon to the polishing rate of an insulating film such as a film having oxygen-silicon bonds. [Means for solving the problem]

[0007] In one aspect of the present invention, the number of silanol groups is 6 / nm 2 More than 22 pieces / nm 2 The polishing composition contains colloidal silica, an alkali metal salt, a polymer compound having an amide bond, a basic amino acid, and water. [Effects of the Invention]

[0008] According to the present invention, a novel polishing composition can be provided that can remove a native oxide film from a film having silicon-silicon bonds such as polysilicon while increasing the ratio of the polishing rate for a film having silicon-silicon bonds such as polysilicon to the polishing rate for an insulating film such as a film having oxygen-silicon bonds, thereby achieving more reliable insulating film stopping and suppressing insulating film loss, thereby solving the trade-off problem. [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 in which oxide loss has occurred 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> In one aspect of the present invention, the number of silanol groups is 6 / nm 2 More than 22 pieces / nm 2 The polishing composition comprises the following: colloidal silica, an alkali metal salt, a polymer compound having an amide bond, a basic amino acid, and water. This embodiment solves the trade-off problem of being able to remove a native oxide film from a film having silicon-silicon bonds such as polysilicon, while increasing the ratio of the polishing rate for a film having silicon-silicon bonds such as polysilicon to the polishing rate for an insulating film such as a film having oxygen-silicon bonds, thereby achieving more reliable insulating film stopping and suppressing insulating film loss.

[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, surprisingly, by using the following, it is possible to remove the native oxide film of a film having silicon-silicon bonds such as polysilicon, while increasing the ratio of the polishing speed of a film having silicon-silicon bonds such as polysilicon to the polishing speed of an insulating film such as a film having oxygen-silicon bonds, thereby achieving a more reliable insulating film stop and suppressing insulating film loss, thereby solving the trade-off problem.

[0014] Colloidal silica with 6 silanol groups / nm 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.

[0015] 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 9.0 pieces / nm 2 More than 10.0 pieces / nm 2 More than 12.0 pieces / nm 2 More than 14.0 pieces / nm 2 or more than 16.0 particles / nm 2 That's all.

[0016] 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 Below, 17.5 pieces / nm 2 Less than 17 particles / nm 2 Below, 16 pieces / nm 2 Below, 15 pieces / nm2 Below, 14 pieces / nm 2 Below, 13 pieces / nm 2 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 following is the result.

[0017] According to one embodiment of the present invention, the number of silanol groups in the colloidal silica is 6.6 / nm 2 Super 17.5 pieces / nm 2 The number of silanol groups is measured by the method described in the Examples.

[0018] 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, 20m 2 / g or more, or 22m 2 / g or more.

[0019] 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.

[0020] 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.

[0021] 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, 91 nm or less, or 80 nm or less.

[0022] 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.

[0023] 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, 115 nm or more, 120 nm or more, more than 120 nm, 130 nm or more, 140 nm or more, 150 nm or more, 160 nm or more, more than 160 nm, 170 nm or more, 180 nm or more, 190 nm or more, 200 nm or more, more than 200 nm, 210 nm or more, 211 nm or more, 212 nm or more, 213 nm or more, 214 nm or more, 215 nm or more, 216 nm or more, 217 nm or more, 218 nm or more, or 219 nm or more.

[0024] 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, 225 nm or less, 200 nm or less, 170 nm or less, or 140 nm or less. The average secondary particle size is measured by the method described in the Examples.

[0025] 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, more than 1.6, 1.7 or more, 1.8 or more, 1.9 or more, 2.0 or more, 2.1 or more, 2.2 or more, or 2.3 or more.

[0026] 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, 2.5 or less, 2.0 or less, or 1.7 or less.

[0027] 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, 1.4 mass% or more, 1.5 mass% or more, 1.6 mass% or more, 1.7 mass% or more, 1.8 mass% or more, or 1.9 mass% or more.

[0028] 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, 4 mass% or less, 3.5 mass% or less, 3 mass% or less, 2.5 mass% or less, or 2 mass% or less.

[0029] According to one embodiment of the present invention, the colloidal silica content of the abrasive grains 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).

[0030] 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).

[0031] According to one embodiment of the present invention, when the concentration of abrasive grains (particularly colloidal silica) contained in the polishing composition is 2 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%. This embodiment is effective in reducing residues on patterned wafers by improving the mechanical action on the object to be polished, such as polysilicon. 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.

[0032] According to one embodiment of the present invention, the transmittance is 0.10% or more, 0.15% or more, 0.17% or more, 0.20% or more, or 0.5% or more. 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.

[0033] Here, when the abrasive concentration of the polishing composition is not 2% by mass, the abrasive concentration can be adjusted to 2% by mass as follows. That is, when the abrasive concentration of the polishing composition is more than 2% by mass, an appropriate amount of water can be added so that the abrasive concentration becomes 2% by mass. When the abrasive concentration of the polishing composition is less than 2% by mass, the polishing composition can be stored in an environment of 25 to 40°C until the abrasive concentration reaches 2% by mass, or a process such as ultrafiltration can be performed.

[0034] [Alkali metal salts] The polishing composition of one embodiment of the present invention contains an alkali metal salt, which can remove a native oxide film from a film having silicon-silicon bonds, such as polysilicon, while increasing the ratio of the polishing rate for a film having silicon-silicon bonds, such as polysilicon, to the polishing rate for an insulating film, such as a film having oxygen-silicon bonds, thereby achieving more reliable insulating film removal and suppressing insulating film loss, thereby resolving the trade-off problem.

[0035] 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.

[0036] The alkali metal salt can also function 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).

[0037] [Basic amino acids] The polishing composition of one embodiment of the present invention contains a basic amino acid, such as L-lysine, D-lysine, DL-lysine, L-arginine, D-arginine, DL-arginine, D-histidine, L-histidine, DL-histidine, D-citrulline, L-citrulline, DL-citrulline, D-ornithine, L-ornithine, or DL-ornithine.

[0038] Among these, histidines such as D-histidine, L-histidine, DL-histidine, etc., and arginines such as L-arginine, D-arginine, DL-arginine, etc. are more preferred, and arginines such as L-arginine, D-arginine, DL-arginine, etc. are even more preferred. According to one embodiment of the present invention, the polishing composition contains arginine as a basic amino acid.

[0039] In one embodiment of the present invention, the mass concentration of the basic amino acid (particularly, arginine) in the object to be polished is 0.001 mass% or more, 0.005 mass% or more, 0.01 mass% or more, 0.05 mass% or more, 0.1 mass% or more, 0.2 mass% or more, 0.3 mass% or more, 0.4 mass% or more, 0.5 mass% or more, 0.6 mass% or more, 0.7 mass% or more, or 0.8 mass% or more.

[0040] In one embodiment of the present invention, the mass concentration of basic amino acids (particularly arginine) in the object to be polished is 8 mass% or less, 6 mass% or less, 4 mass% or less, 2 mass% or less, 1.5 mass% or less, 1.4 mass% or less, 1.3 mass% or less, 1.2 mass% or less, 1.1 mass% or less, 1.0 mass% or less, 0.9 mass% or less, 0.8 mass% or less, 0.6 mass% or less, or 0.5 mass% or less.

[0041] In one embodiment of the present invention, the mass concentration of the basic amino acid (particularly, arginine) in the polishing object is 0.5 to 1 mass %. Within this range, the ratio of the polishing rate of the film having silicon-silicon bonds such as polysilicon to the polishing rate of the insulating film such as the film having oxygen-silicon bonds can be increased to achieve more reliable insulating film stopping, while removing a native oxide film of the film having silicon-silicon bonds such as polysilicon, and insulating film loss can be more significantly suppressed.

[0042] [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 remove native oxide from a film having silicon-silicon bonds, such as polysilicon, while increasing the ratio of the polishing rate for a film having silicon-silicon bonds, such as polysilicon, to the polishing rate for an insulating film, such as a film having oxygen-silicon bonds, thereby achieving more reliable insulating film removal and suppressing insulating film loss, thereby resolving the trade-off problem. 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 an acyclic amide structure, such as polyacrylamide or poly-N-vinylacetamide.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] According to one embodiment of the present invention, the polymer compound having an amide bond is represented by the following formula (1):

[0047] [ka]

[0048] In the above formula (1), A is a group selected from at least one of the following:

[0049] [ka]

[0050] 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, the repeating unit may contain at least one oxygen atom in the ring. In Formula 1-1, "containing at least one oxygen atom in the ring" means that some bonds with "-CH2-CH2-CH2-" may be replaced with bonds with "-CH-O-CH-". In addition, * indicates the bonding site. The number of oxygen atoms contained in the ring is independently 1 or 2, for example.

[0051] 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.

[0052] In one embodiment of the present invention, m is 1, 2, 3 or 4.

[0053] 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.

[0054] In one embodiment of the present invention, R 1 and R 2 At least one of the groups is a hydrogen atom.

[0055] 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.

[0056] In one embodiment of the present invention, in a polymer compound having an amide bond, repeating units in which A is at least one of formula (1-1), formula (1-2), and formula (1-3) account for 90 mol % or more, or 95 mol % or more (upper limit 100 mol %), in the polymer compound having an amide bond. In one embodiment of the present invention, in a polymer compound having an amide bond, repeating units in which A is formula (1-1) account for 90 mol % or more, or 95 mol % or more (upper limit 100 mol %), in the polymer compound having an amide bond.

[0057] 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, 40 mol% or more, 50 mol% or more, 60 mol% or more, 70 mol% or more, 80 mol% or more, 90 mol% or more, or 95 mol% or more (upper limit: 100 mol%).

[0058] 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, a suitable example of a polymer containing an N-vinyl chain amide repeating unit is a vinylacetamide-based polymer. Here, a 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 a vinylacetamide-based polymer, the proportion of the number of moles of vinylacetamide units to the number of moles of all repeating units is suitably 20 mol% or more, 25 mol% or more, 30 mol% or more, 40 mol% or more, 50 mol% or more, 60 mol% or more, 70 mol% or more, 80 mol% or more, 90 mol% or more, or 95 mol% or more (upper limit: 100 mol%).

[0059] 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 in the number of moles of all repeating units is suitably 20 mol% or more, 25 mol% or more, 30 mol% or more, 40 mol% or more, 50 mol% or more, 60 mol% or more, 70 mol% or more, 80 mol% or more, 90 mol% or more, or 95 mol% or more (upper limit: 100 mol%).

[0060] In one embodiment of the present invention, the polymer compound having an amide bond may be polyvinylpyrrolidone, polyacrylamide, or poly-N-vinylacetamide. Among these, polyvinylpyrrolidone is preferred from the viewpoint that it can remove a native oxide film of a film having silicon-silicon bonds such as polysilicon while increasing the ratio of the polishing rate of a film having silicon-silicon bonds such as polysilicon to the polishing rate of an insulating film such as a film having oxygen-silicon bonds, thereby achieving more reliable insulating film stopping and significantly suppressing insulating film loss.

[0061] In one embodiment of the present invention, the weight average molecular weight of the polymer compound having an amide bond (particularly, polyvinylpyrrolidone) is 1,000 or more, 2,000 or more, 4,000 or more, 6,000 or more, 8,000 or more, 10,000 or more, 20,000 or more, 30,000 or more, 40,000 or more, 43,000 or more, or 47,000 or more.

[0062] In one embodiment of the present invention, the weight average molecular weight of the polymer compound having an amide bond (particularly, polyvinylpyrrolidone) is 90,000 or less, 80,000 or less, 70,000 or less, 60,000 or less, 55,000 or less, 50,000 or less, 40,000 or less, 30,000 or less, or 20,000 or less.

[0063] In one embodiment of the present invention, the weight average molecular weight of the polymer compound having an amide bond (particularly poly-N-vinylacetamide) is 10,000 or more, 20,000 or more, 30,000 or more, 40,000 or more, or 45,000 or more.

[0064] In one embodiment of the present invention, the weight average molecular weight of the polymer compound having an amide bond (particularly poly-N-vinylacetamide) is 100,000 or less, 80,000 or less, 70,000 or less, 60,000 or less, or 55,000 or less.

[0065] In one embodiment of the present invention, the weight average molecular weight of the polymer compound having an amide bond (particularly polyacrylamide) is 1,000 or more, 2,000 or more, 4,000 or more, 6,000 or more, 8,000 or more, 10,000 or more, 20,000 or more, 30,000 or more, or 35,000 or more.

[0066] In one embodiment of the present invention, the weight average molecular weight of the polymer compound having an amide bond (particularly polyacrylamide) is 90,000 or less, 80,000 or less, 70,000 or less, 60,000 or less, 55,000 or less, 50,000 or less, or 45,000 or less.

[0067] In one embodiment of the present invention, the polymer compound having an amide bond may be prepared by appropriately combining compounds having different molecular weights. The appropriate combination of compounds having different molecular weights refers to, for example, mixing a polymer compound having an amide bond and having a relatively high molecular weight (e.g., polyvinylpyrrolidone) with a polymer compound having an amide bond and having a relatively low molecular weight (e.g., polyvinylpyrrolidone). According to one embodiment of the present invention, the mixing mass ratio of the polymer compound having an amide bond and having a relatively high molecular weight to the polymer compound having an amide bond and having a relatively low molecular weight is 1:0.5 to 1:2.

[0068] In one embodiment of the present invention, the molecular weight distribution of the polymer compound having an amide bond (e.g., polyvinylpyrrolidone) is unimodal. The unimodal molecular weight distribution of the polymer compound having an amide bond (e.g., polyvinylpyrrolidone) allows for the removal of native oxide films from films having silicon-silicon bonds, such as polysilicon, while increasing the ratio of the polishing rate for films having silicon-silicon bonds, such as polysilicon, to the polishing rate for insulating films, such as films having oxygen-silicon bonds, thereby achieving more reliable insulating film removal and significantly suppressing insulating film loss.

[0069] In one embodiment of the present invention, the mass concentration of the polymer compound having an amide bond (e.g., polyvinylpyrrolidone) 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, 12 mass ppm or more, 14 mass ppm or more, 16 mass ppm or more, or 18 mass ppm or more.

[0070] In one embodiment of the present invention, the mass concentration of the polymer compound having an amide bond (e.g., polyvinylpyrrolidone) in the object to be polished is 200 ppm by mass or less, 150 ppm by mass or less, 100 ppm by mass or less, 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, or 25 ppm by mass or less. Having such upper and lower limits increases the ratio of the polishing rate for a film having silicon-silicon bonds, such as polysilicon, to the polishing rate for an insulating film having oxygen-silicon bonds, thereby achieving a more reliable oxide stop while suppressing oxide loss.

[0071] [pH] In one embodiment of the present invention, the pH of the polishing composition is 9.0 to 11.5. When the pH of the polishing composition is in this range, the ratio of the polishing rate of a film having silicon-silicon bonds such as polysilicon to the polishing rate of an insulating film having oxygen-silicon bonds is increased, thereby achieving a more reliable oxide stop while suppressing oxide loss, which is a significant effect.

[0072] 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, 9.6 or more, 9.7 or more, 9.8 or more, 9.9 or more, 10.0 or more, 10.0 or more, 10.1 or more, more than 10.2, 10.3 or more, or 10.4 or more.

[0073] According to one embodiment of the present invention, the pH of the polishing composition is 11.4 or less, 11.3 or less, 11.2 or less, 11.1 or less, 11.0 or less, less than 11.0, 10.9 or less, 10.8 or less, 10.7 or less, or 10.6 or less. The pH of the polishing composition is measured by the method described in the Examples. According to one embodiment of the present invention, the pH of the polishing composition is preferably more than 10.2 and less than 11.0.

[0074] [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, to expose the first layer, the second layer being selected from those having oxygen-silicon bonds or nitrogen-silicon bonds, and the second layer having silicon-silicon bonds. FIG. 1 is a schematic cross-sectional view of the polishing object (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) 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 to fill the recess, thereby forming a polishing object 10 including the first layer and the second layer.

[0075] 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, has an ideal polished surface in which the amount of the object to be polished that should be polished is reduced (no residue), dishing of the film having silicon-silicon bonds is suppressed, and insulating film loss is significantly reduced.

[0076] According to one embodiment of the present invention, the polished object 1 cm 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.

[0077] When a polishing object 10 including a first layer and a second layer is polished with a polishing composition other than the polishing composition of the present invention (i.e., a comparative polishing composition), for example, an insulating film loss 2a occurs as shown in FIG. 3, or a residue 2b of the object to be polished (a film having silicon-silicon bonds) occurs as shown in FIG. 4, or both occur simultaneously as shown in FIG. 5. More specifically, FIG. 3 schematically shows that the difference in height between the insulating film region (field region) where wiring is not densely packed and the narrow insulating film region (space region) between wirings is caused by the insulating film loss 2a. FIG. 4 schematically shows that a residue 2b of the film having silicon-silicon bonds occurs significantly on the insulating film region (field region) where wiring is not densely packed.

[0078] 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" or "silicon dioxide") 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), etc. The TEOS film may be formed by plasma CVD.

[0079] In one embodiment of the present invention, the object to be polished having a nitrogen-silicon bond may be a silicon nitride film or SiCN (silicon carbonitride).

[0080] In one embodiment of the present invention, examples of the object to be polished having silicon-silicon bonds 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.

[0081] [Polishing speed] According to one embodiment of the present invention, the polishing composition has physical properties such that the polishing rate of the first layer is 4 Å / min or more, 5 Å / min or more, 6 Å / min or more, 7 Å / min or more, 8 Å / min or more, 9 Å / min or more, 10 Å / min or more, 11 Å / min or more, 12 Å / min or more, 13 Å / min or more, 14 Å / min or more, 15 Å / min or more, 20 Å / min or more, 25 Å / min or more, or 30 Å / min or more.

[0082] According to one embodiment of the present invention, the polishing composition has physical properties that result in a polishing rate for the first layer of 40 Å / min or less, 35 Å / min or less, 30 Å / min or less, 25 Å / min or less, or 20 Å / min or less.

[0083] 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 3000 Å / min or more, 3200 Å / min or more, 3400 Å / min or more, 3600 Å / min or more, 3800 Å / min or more, 4000 Å / min or more, 4200 Å / min or more, or 4000 Å / min or more.

[0084] 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 5000 Å / min or less, 4800 Å / min or less, 4600 Å / min or less, 4400 Å / min or less, 4200 Å / min or less, 4000 Å / min or less, 3800 Å / min or less, 3600 Å / min or less, or 3400 Å / min or less.

[0085] [Selection ratio] According to one embodiment of the present invention, the polishing composition has physical properties such that the ratio (selectivity) of the polishing rate (Å / min) of the second layer to the polishing rate (Å / min) of the first layer is greater than 40, 70 or more, 100 or more, 100 or more, 130 or more, 160 or more, 190 or more, 210 or more, 240 or more, 270 or more, 310 or more, 400 or more, 500 or more, or 600 or more.

[0086] According to one embodiment of the present invention, the polishing composition has physical properties such that the ratio (selectivity) of the polishing rate (Å / min) of the second layer to the polishing rate (Å / min) of the first layer is 800 or less, 650 or less, 550 or less, 450 or less, 390 or less, 350 or less, 300 or less, 280 or less, 260 or less, 250 or less, 240 or less, 220 or less, 200 or less, or 150 or less.

[0087] According to one embodiment of the present invention, the ratio (Å / min) of the polishing rate of the second layer to the polishing rate (Å / min) of the first layer is 190-390.

[0088] [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 %).

[0089] [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.

[0090] 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.

[0091] According to one embodiment of the present invention, the number of silanol groups is 6 / nm 2 More than 22 pieces / nm 2 The polishing composition is substantially composed of the following colloidal silica, an alkali metal salt (particularly potassium hydroxide), a polymer compound having an amide bond (particularly polyvinylpyrrolidone), a basic amino acid (particularly arginine), water, and a preservative. 2 More than 22 pieces / nm 2 The above explanations can be applied to the following descriptions of colloidal silica, alkali metal salt, polymeric compound having an amide bond, basic amino acid, and water. The explanation of "substantially composed" will be given later.

[0092] [Other ingredients] According to one embodiment of the present invention, the polishing composition is substantially free of at least one of surfactants, oxidizing agents, and compounds having a nitrogen atom (excluding polymeric compounds having an amide bond and basic amino acids). Here, "substantially free" means that the component is completely absent (below the detection limit), unless otherwise specified, or that the component is present in an amount of 0.1% by mass or less, 0.01% by mass or less, 0.001% by mass or less, or 0.0001% by mass or less in the polishing composition.

[0093] 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; 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, such as 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. The term "one type" used in this section may refer to either a "genus" of "surfactant" or a "species," such as "polyoxyethylene lauryl ether." This explanation applies to the explanation of "oxidizing agents" as well as to the explanation of compounds having a nitrogen atom (excluding polymeric compounds having an amide bond and basic amino acids).

[0094] The oxidizing agent may be a substance having a redox potential higher than that of the substrate material (particularly a material having silicon-silicon bonds) at the pH at which polishing is performed. Here, the pH at which polishing is performed is usually 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 a material having silicon-silicon bonds) 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.

[0095] 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.

[0096] According to one embodiment of the present invention, the polishing composition is substantially free of abrasive grains other than colloidal silica.

[0097] 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.

[0098] According to one embodiment of the present invention, the polishing composition is substantially free of silica having amino groups fixed to the surface thereof.

[0099] 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 - 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 object to be polished (particularly polysilicon), which has a high degree of water repellency, and the colloidal silica is likely to remain as residue.

[0100] According to one embodiment of the present invention, the polishing composition does not contain any of hydroxyalkyl cellulose, carrageenan, and xanthan gum.

[0101] 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.

[0102] In one embodiment of the present invention, the number of silanol groups is 6 / nm 2 More than 22 pieces / nm 2 The polishing composition is substantially composed of the following colloidal silica, an alkali metal salt (particularly potassium hydroxide), a polymer compound having an amide bond (particularly polyvinylpyrrolidone), a basic amino acid (particularly arginine), and water. 2 More than 22 pieces / nm 2 The above explanations can be applied to the following explanations of colloidal silica, alkali metal salt, polymer compound having an amide bond, basic amino acid, and water.

[0103] Here, "substantially composed" means that the polishing composition has a silanol group count of 6 / nm 2 More than 22 pieces / nm 2 When the polishing composition contains components other than the following colloidal silica, alkali metal salt (especially potassium hydroxide), polymeric compound having an amide bond (especially polyvinylpyrrolidone), basic amino acid (especially arginine), water, and optionally contained preservatives, the ratio of these components (the total of these components) in the polishing composition is 0.1 mass% or less, 0.01 mass% or less, 0.001 mass% or less, or 0.0001 mass% or less.

[0104] 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.

[0105] <Method for producing polishing composition> In one embodiment of the present invention, a method for producing a polishing composition includes mixing colloidal silica, an alkali metal salt, a polymeric compound having an amide bond, a basic amino acid, water, and an optional preservative. The above explanations for the colloidal silica, the alkali metal salt, the polymeric compound having an amide bond, the basic amino acid, water, and the optional preservative are applicable. The temperature at which the components are mixed is not particularly limited, but is preferably 10°C or higher and 40°C or lower, 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.

[0106] <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.

[0107] 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.

[0108] 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 whose rotation speed can be changed, and a polishing platen onto which a polishing pad (polishing cloth) can be attached.

[0109] 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.

[0110] 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.

[0111] The present invention encompasses the following aspects and configurations.

[0112] 1. 6 silanol groups / nm 2 More than 22 pieces / nm 2A polishing composition comprising the following colloidal silica, an alkali metal salt, a polymer compound having an amide bond, a basic amino acid, and water.

[0113] 2. A polishing composition according to 1, which is used in a process of polishing a first layer having a recess and a second layer formed to fill the recess, thereby exposing the first layer, and which is selected from those having an oxygen-silicon bond or a nitrogen-silicon bond, and which is used in a process of polishing a first layer having a recess and a second layer formed to fill the recess, wherein the first layer has a silicon-silicon bond.

[0114] 3. The polishing composition according to 2., wherein the ratio of the polishing rate (Å / min) of the second layer to the polishing rate (Å / min) of the first layer is 190 to 390.

[0115] 4. The polishing composition according to any one of 1. to 3., wherein the molecular weight distribution of the polymer compound having an amide bond is unimodal.

[0116] 5. The polishing composition according to any one of 1. to 4., wherein the colloidal silica has an average secondary particle size of more than 200 nm.

[0117] 6. The pulse NMR specific surface area of ​​the colloidal silica is 40m 2 6. The polishing composition according to any one of 1. to 5., wherein the polishing composition has a viscosity of 1 / g or less.

[0118] 7. A polishing composition according to any one of 1. to 6., wherein when the concentration of the colloidal silica is 2% by mass, the transmittance when light with a wavelength of 450 nm is transmitted is more than 0.1% and less than 1%.

[0119] 8. The polymer compound having an amide bond is represented by the following formula (1):

[0120] [ka]

[0121] In the above formula (1), A is a group selected from at least one of the following:

[0122] [ka]

[0123] 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 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.

[0124] 9. The polishing composition according to any one of 1. to 8., wherein the alkali metal salt is an alkali metal hydroxide.

[0125] 10. The polishing composition according to any one of 1. to 9., which contains arginine as the basic amino acid.

[0126] 11. 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, a basic amino acid, and water.

[0127] 12. 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 polymeric compound having an amide bond, a basic amino acid, water, and a preservative. [Example]

[0128] 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.

[0129] <Production of Polishing Composition> Polishing compositions were prepared by mixing abrasive grains (colloidal silica), an alkali metal salt, a basic amino acid, a polymer compound, and water to obtain the compositions shown in Table 1. For example, the polishing composition of Example 1 had an average primary particle size of 90 nm, an average secondary particle size of 220 nm, and a pulse NMR specific surface area of ​​23.8 m 2 / g, 7.9 silanol groups / nm 2 The composition contained 2% by mass of colloidal silica (amount of ammonium hydroxide), potassium hydroxide, 8.39 g / kg of L-arginine, 20 ppm by mass of polyvinylpyrrolidone (PVP) (weight-average molecular weight 45,000), and water, and had a pH of 10.5. A blank space in the table indicates that the component was not added. The average primary particle diameters of the colloidal silica in Examples 4 and 5 were 70 nm and 100 nm, respectively.

[0130] [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 "Macsorb (registered trademark) HM model-1210" manufactured by Mountech Co., Ltd., and the density of the abrasive grains.

[0131] 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.

[0132] [Calculation method for 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.

[0133] 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.

[0134] 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.

[0135] 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 "Macsorb (registered trademark) HM model-1210" manufactured by Mountech Co., Ltd.

[0136] [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 system (manufactured by Xigo Nanotools), and the results are shown in Table 1.

[0137] (Measurement conditions) Bulk relaxation time: 2409ms Specific surface relaxivity:0.00026 Volume ratio of particles to liquid:0.1136.

[0138] [Weight average molecular weight] In this specification, the "weight average molecular weight" can be a value of 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.

[0139] [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.

[0140] [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.

[0141] [Measurement of polishing speed] The polishing composition was used to polish the surface of an object 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, and a silicon wafer (300 mm, blanket wafer) with a 10000 Å thick P-TEOS film (a TEOS film (silicon dioxide film) formed by plasma CVD) formed on its surface.

[0142] Since the blanket wafers on which the Poly-Si film was formed have a native oxide film of about 5 Å on their surfaces, the native oxide film was removed by polishing the blanket wafers on which the Poly-Si film was formed under the polishing conditions described below using an aqueous dispersion of colloidal silica containing 5 mass % of colloidal silica having an average secondary particle diameter of 70 nm. These wafers were then used as wafers for measuring the polishing rate.

[0143] (polishing conditions) Polishing equipment: Applied Materials 300mm CMP single-sided polishing equipment Reflexion LK Pad: Nitta Haas Corporation hard polyurethane pad IC1010 Polishing pressure: 2.0 psi (1 psi = 6894.76 Pa, same below) Polishing platen rotation speed: 93 rpm Carrier rotation speed: 87 rpm Supply of polishing composition: Pouring Supply rate of polishing composition: 200 ml / min Polishing time: 60 seconds

[0144] The polishing rate was measured by obtaining the thickness with an optical film thickness measuring instrument (RE-3500, manufactured by SCREEN Co., Ltd.) and dividing (thickness before polishing) - (thickness after polishing) by the polishing time.

[0145] Also, the ratio of the polishing rate of the polysilicon film (Å / min) to the polishing rate of the P-TEOS film (Å / min) was calculated as the selection ratio.

[0146] <Evaluation of native oxide removal on Poly-Si> A blanket wafer on which a Poly-Si film was formed (native oxide film not removed) was polished under the conditions of [measurement of polishing rate] (polishing conditions). The change in the thickness of the native oxide film at that time was measured using an optical film thickness measuring instrument (RE-3500, manufactured by SCREEN Co., Ltd.), and the time when the thickness of the native oxide film became 0 Å was evaluated as the time when the native oxide film could be removed = the time when the polishing rate of Poly-Si was exhibited.

[0147] ◎: The native oxide film could be removed between 15 seconds and less than 20 seconds of polishing time.

[0148] 〇: The native oxide film could be removed between 20 seconds and less than 25 seconds after the start of polishing.

[0149] △: The native oxide film could be removed after 25 seconds or more had elapsed since the start of polishing.

[0150] <Residual polysilicon (polishing residue)> A patterned wafer with a polysilicon film was polished using the polishing composition under the above-mentioned polishing conditions. As shown in Figure 1, the patterned wafer was prepared by laminating a P-TEOS 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) to fill the recess. The polysilicon film had a native oxide film of about 5 Å on its surface.

[0151] After the endpoint signal was detected, 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, a process of further polishing the first layer (P-TEOS film) after the first layer (P-TEOS film) was exposed was realized.

[0152] After polishing, the thickness of the polysilicon remaining on the P-TEOS film area (field area) where the wiring was not densely packed was measured using a cross-sectional SEM (model HD2700; Hitachi High-Tech Corporation). The thickness at this point was taken as the unpolished portion and was evaluated according to the following three-level evaluation criteria. △ and × are unacceptable for practical use. The results are shown in Table 1.

[0153] ○: Less than 5Å △: 5 Å or more and less than 10 Å ×: 10 Å or more.

[0154] <Evaluation of insulating film loss (oxide loss)> After polishing, the height difference between the P-TEOS film area where the wiring was not dense (field area) and the narrow P-TEOS film area between the wiring (space area) was measured using a Bruker Insight CAP (AFM) and evaluated as oxide loss. The width of the wiring and space area was 0.18 μm, respectively.

[0155] [Table 1]

[0156] <Consideration> The polishing compositions of the Examples remove native oxide films of polysilicon while increasing the ratio of the polishing rate of the polysilicon film to the polishing rate of an insulating film such as a TEOS film (silicon dioxide film), thereby achieving more reliable insulating film stopping and suppressing insulating film loss (oxide loss), thereby solving the trade-off problem. In particular, the polishing composition of Example 1 is excellent at removing native oxide films while significantly suppressing oxide loss. It also reliably suppresses the remaining polysilicon (polishing residue).

[0157] Examples 2 and 3 are examples in which the PVP contained in the polishing composition of Example 1 was replaced with PNVA and PAA, respectively. While Examples 2 and 3 excel in removing native oxide films like Example 1, the oxide loss is slightly worse. These results suggest that PVP is superior to PNVA and PAA as a polymeric compound having an amide bond to be contained in a polishing composition.

[0158] Examples 4 and 5 are examples in which the type of abrasive grains contained in the polishing composition of Example 1 was changed. While Examples 4 and 5 exhibited excellent native oxide film removal, as in Example 1, oxide loss was slightly worse. The results of Example 4 revealed that as the number of silanol groups in colloidal silica decreased, the polishing rate for polysilicon and TEOS (silicon dioxide) decreased overall. Despite the decreased polishing rate for TEOS (silicon dioxide), oxide loss slightly worsened. On the other hand, the results of Example 5 revealed that as the number of silanol groups in colloidal silica increased, the polishing rate for polysilicon and TEOS (silicon dioxide) increased overall. Consequently, oxide loss also slightly worsened. The colloidal silicas of Examples 4 and 5 have opposite characteristics to those of the colloidal silica of Example 1 in terms of the number of silanol groups. However, the use of colloidal silicas with such opposite characteristics resulted in a similar result of slightly worsening oxide loss, which can be considered an unexpected result. In any case, the results of Examples 1, 4, and 5 indicate that the number of silanol groups in colloidal silica is 6.6 / nm 2Super 17.5 pieces / nm 2 It is suggested that it is more preferable that the .beta.

[0159] In Example 6, the PVP content of the polishing composition of Example 1 was reduced by half to 10 ppm by mass, replacing it with a PVP with a relatively low molecular weight. As a result, while Example 6 exhibited excellent native oxide film removal, similar to Example 1, the oxide loss was slightly worse. The molecular weight distribution of the PVP contained in the polishing composition of Example 6 was bimodal, which can be understood simply as meaning that PVPs with various molecular weights were present in the polishing composition of Example 6. In such a case, PVP would normally be able to uniformly protect the polishing target film. In fact, the removal rates of polysilicon and TEOS in Example 6 were lower than those in Example 1, so it was expected that oxide loss would actually be suppressed. However, contrary to expectations, the oxide loss was slightly worsened. Therefore, the results of Examples 1 and 6 suggest that a unimodal molecular weight distribution is preferable for polymeric compounds with amide bonds, such as PVP.

[0160] Example 7 is an example in which an experiment was conducted by varying the pH of the polishing composition based on Example 1. As shown in Example 7, it was found that increasing the pH of the polishing composition improved the removal rate of polysilicon and TEOS (silicon dioxide), but also slightly worsened the oxide loss.

[0161] Examples 8 and 9 are experiments in which the arginine concentration was varied based on Example 1. The results of Examples 8 and 9 suggest that arginine has a strong protective effect on the TEOS film. Specifically, the polishing composition of Example 8 has a relatively high arginine concentration, which enhances TEOS protection and reduces the TEOS (silicon dioxide) removal rate. As a result, the native oxide film cannot be effectively removed, and for unknown reasons, oxide loss also worsens slightly. On the other hand, the polishing composition of Example 9 has a low arginine concentration, which weakens TEOS protection and increases the TEOS (silicon dioxide) removal rate, resulting in slightly worse oxide loss.

[0162] Comparative Example 1 is an example in which the polymer compound having an amide bond was omitted from the polishing composition of Example 1. As a result, although the selectivity ratio of polysilicon / TEOS was within an appropriate range as in Example 1, the oxide loss worsened. In other words, it is suggested that there is not necessarily a direct causal relationship between keeping the selectivity ratio of polysilicon / TEOS within an appropriate range and the presence or absence of oxide loss. Thus, it is suggested that a polymer compound having an amide bond is essential to suppress oxide loss while removing native oxide films.

[0163] Comparative Example 2 is an example in which the basic amino acid was omitted from the polishing composition of Example 1. As a result, the protection of TEOS was almost eliminated, the removal rate of TEOS (silicon dioxide) increased, and oxide loss could not be suppressed accordingly. In other words, it is suggested that a basic amino acid is essential for suppressing oxide loss while removing the native oxide film.

[0164] Comparative Example 3 is an example in which the alkali metal salt was omitted from the polishing composition of Example 1. As a result, not only was it almost impossible to remove the native oxide film, but the oxide loss also deteriorated significantly. In other words, it is suggested that the alkali metal salt is essential for suppressing the oxide loss while removing the native oxide film.

[0165] Comparative Example 4 is an example in which aminoethylpiperazine was added instead of the alkali metal salt contained in the polishing composition of Example 1 to adjust the pH. As a result, not only was it almost impossible to remove the native oxide film, but the oxide loss also deteriorated significantly. This suggests that the alkali metal salt is essential for removing the native oxide film while suppressing the oxide loss.

[0166] In Comparative Examples 5 and 6, the polishing composition of Example 1 contained an average secondary particle diameter of 220 nm and a number of silanol groups of 7.9 / nm 2 Instead of colloidal silica, which has an average secondary particle diameter of 80 nm and a silanol group number of 1.5 / nm2 Colloidal silica with an average secondary particle diameter of 30 nm and 3.1 silanol groups per nm 2 This is an example of using colloidal silica with a silanol group count of 6 / nm. As a result, not only was it almost impossible to remove the native oxide film, but oxide loss also worsened significantly, and some polysilicon was left unpolished. In other words, in order to remove the native oxide film while also suppressing oxide loss, the colloidal silica should have a silanol group count of 6 / nm. 2 It is suggested that the above is essential.

[0167] In Comparative Example 7, the polishing composition of Example 1 contained an average secondary particle diameter of 220 nm and a number of silanol groups of 7.9 / nm 2 Instead of colloidal silica, which has an average secondary particle diameter of 370 nm and 23.8 silanol groups per nm, 2 This is an example of using colloidal silica with a silanol group density of 22 / nm. As a result, the polishing speed for polysilicon and TEOS (silicon dioxide) increased significantly, and oxide loss could not be suppressed. In other words, in order to suppress oxide loss while removing the native oxide film, the colloidal silica must have a silanol group density of 22 / nm. 2 It is suggested that the following is essential:

[0168] In Comparative Example 8, the polishing composition of Example 1 contained an average secondary particle diameter of 220 nm and a silanol group number of 7.9 / nm 2 Instead of colloidal silica, which has an average secondary particle diameter of 220 nm and 2.5 silanol groups per nm, 2 This is an example of using colloidal silica with a silanol group count of 6 / nm. Not only was it almost impossible to remove the native oxide film, but oxide loss also worsened significantly, and some polysilicon was left unpolished. Therefore, in order to remove the native oxide film while also suppressing oxide loss, it is necessary to use colloidal silica with a silanol group count of 6 / nm. 2 It is suggested that the above is essential.

[0169] Comparative Example 9 is an example in which a different polymer compound was used instead of the polymer compound having an amide bond contained in the polishing composition of Example 1. As a result, the oxide loss was significantly increased. In other words, it is suggested that a polymer compound having an amide bond is essential for removing the native oxide film while suppressing the oxide loss. [Explanation of symbols]

[0170] 1 first layer, 2 second layer, 2a Insulation film loss, 2b Remaining second layer to be polished 10. Object to be polished; 10' Polished object.

Claims

1. 6 silanol groups / nm ２ More than 22 pieces / nm ２ and colloidal silica, an alkali metal salt; a polymer compound having an amide bond; a basic amino acid, Water and A polishing composition comprising:

2. The polishing method is used in a step of polishing a first layer having a recess and a second layer formed to fill the recess, to expose the first layer, 2. The polishing composition according to claim 1, wherein the first layer is selected from those having an oxygen-silicon bond or a nitrogen-silicon bond, and the second layer has a silicon-silicon bond.

3. 3. The polishing composition according to claim 2, wherein the ratio of the polishing rate (Å / min) of the second layer to the polishing rate (Å / min) of the first layer is 190 to 390.

4. 2. The polishing composition according to claim 1, wherein the molecular weight distribution of the polymer compound having an amide bond is unimodal.

5. 2. The polishing composition according to claim 1, wherein the colloidal silica has an average secondary particle size of more than 200 nm.

6. 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.

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

8. 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.

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

10. The polishing composition according to claim 1 , wherein the basic amino acid is arginine.

11. 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, a basic amino acid, and water.

12. 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 polymeric compound having an amide bond, a basic amino acid, water, and a preservative.

Images