Polishing composition

Abstract

To provide a new polishing composition that can reduce the remaining of an object to be polished, such as polysilicon, and suppress recesses.SOLUTION: Provided is a polishing composition comprising colloidal silica; an alkali metal salt; polyalkylene glycol; at least one of a cellulose derivative and a polymer compound X; and water, the polishing composition having a pH of 9.0 to 11.5, the polymer compound X containing a repeating unit represented by the following formula (1). In the formula (1), A is at least one group selected from the followings.SELECTED DRAWING: None

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 a recess is placed on a polysilicon film formed to fill the recess, and polishing is sometimes performed using the silicon dioxide film as a stopper film.

[0003] The selectivity, which is the ratio of the rate at which a polysilicon film is polished to the rate at which a silicon dioxide film is polished, is used as an index of how easily a polysilicon film is polished relative to a silicon dioxide film. This is calculated by dividing the rate at which a polysilicon film is polished by that of a silicon dioxide film. In order for the silicon dioxide film to function as a stopper layer, a larger selectivity is preferable. For example, Patent Document 1 provides a polishing composition that achieves a large selectivity and minimizes the occurrence of surface defects, and the polishing composition comprises an abrasive such as silicon dioxide and water, and may further contain a basic organic compound such as tetramethylammonium hydroxide.

[0004] 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]

[0005] [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]

[0006] In the process of developing a new polishing composition, the inventors discovered that with conventional techniques, even if the selectivity was controlled, the object to be polished, such as polysilicon, would remain after polishing, or a recess would occur.

[0007] Therefore, an object of the present invention is to provide a novel polishing composition that can reduce the amount of residue of the object to be polished, such as polysilicon, and also suppress recesses. [Means for solving the problem]

[0008] One aspect of the present invention is a solution containing colloidal silica, an alkali metal salt, a polyalkylene glycol, at least one of a cellulose derivative and a polymer compound X, and water, and having a pH of 9.0 to 11.5; The polymer compound X is represented by the following formula (1):

[0009] [ka]

[0010] In the above formula (1), A is a group selected from at least one of the following:

[0011] [ka]

[0012] 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, and in Formula 1-1, R 1 and R 2may 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 may contain at least one oxygen atom in the ring, The polymer compound X is represented by the following formula (2):

[0013] [ka]

[0014] In the above formula (2), A is a hydroxyl group, and the repeating unit may further contain the following repeating unit: (i) A polishing tool 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, 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. and / or (ii) The number of silanol groups in the colloidal silica is 6 / nm 2 More than 22 pieces / nm 2 The polishing composition is as follows: [Effects of the Invention]

[0015] According to the present invention, it is possible to provide a novel polishing composition which can reduce the amount of residue of an object to be polished, such as polysilicon, and can also suppress recesses. [Brief explanation of the drawings]

[0016] [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

[0017] 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.

[0018] <Polishing composition> One aspect of the present invention is a composition comprising colloidal silica, an alkali metal salt, a polyalkylene glycol, at least one of a cellulose derivative and a polymer compound X, and water, wherein the pH is 9.0 to 11.5, and the polymer compound X is represented by the following formula (1):

[0019] [ka]

[0020] In the above formula (1), A is a group selected from at least one of the following:

[0021] [ka]

[0022] 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, it may contain at least one oxygen atom, and in formula 1-1, at least one oxygen atom may be contained in the ring, and the polymer compound X contains a repeating unit represented by the following formula (2):

[0023] [ka]

[0024] The colloidal silica may further contain a repeating unit represented by the formula (2), wherein A is a hydroxyl group; (i) the colloidal silica is used in a step of polishing a first layer having a recess and a second layer formed so as to fill the recess, to expose the first layer, the second layer being polished, 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 The polishing composition is as follows: According to this embodiment, it is possible to provide a novel polishing composition that can reduce the amount of residue of the object to be polished, such as polysilicon, and also suppress recesses.

[0025] The mechanism by which such technical effects are exhibited is considered to be as follows: In the alkaline pH range, hydroxide ions (OH -), and the surface of the workpiece to be polished, such as polysilicon, which has silicon-silicon bonds, is converted to silanol groups (SiOH). During polishing, the silanol-containing workpiece converted to silanol groups (SiOH) and the colloidal silica, which has a silanol group number within the above range, react through hydrogen bonding, thereby reducing residues on the patterned wafer. Furthermore, the use of an alkali metal salt is thought to suppress excessive etching of the workpiece to be polished, which has silicon-silicon bonds, thereby effectively suppressing recess formation. In addition, the cellulose derivative and / or polymer compound X in the polishing composition is believed to adsorb to the polysilicon surface, thereby protecting the polysilicon surface and further suppressing the occurrence of recesses. Meanwhile, the cellulose derivative and / or polymer compound X may hinder the removal of silicon and other substances locally remaining on the patterned wafer, potentially increasing the amount of silicon and other substances remaining. However, the presence of polyalkylene glycol, which has a relatively low adsorption force to silicon and other substances, is thought to suppress this. In other words, it is believed that the polishing composition of the present invention achieves a high level of both reducing the amount of remaining material to be polished, such as polysilicon, and suppressing recesses, due to the combination of the above-mentioned multiple mechanisms. However, such mechanisms are merely speculation, and the technical scope of the present invention is not limited by such mechanisms.

[0026] [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.

[0027] 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 2Although the detailed mechanism is unknown, surprisingly, by using the following, the remaining of the polishing target material such as polysilicon is reduced and recessing is promoted. In other words, when the number of silanol groups in colloidal silica is 6 / nm 2 Less than 22 particles / nm 2 If the number of silanol groups in the colloidal silica is less than 6 / nm, there is a risk that the amount of material to be polished, such as polysilicon, remaining may increase or recesses may be promoted. 2 More than 22 pieces / nm 2 An 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.

[0028] 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.

[0029] 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 / 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 number of silanol groups was measured by the method described in the Examples.

[0030] 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 20m2 / 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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).

[0040] 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).

[0041] [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.

[0042] 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.

[0043] 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).

[0044] 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 the abrasive grains (particularly colloidal silica), polyalkylene glycol, cellulose derivative, polymer compound X, or 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.

[0045] [Polyalkylene glycol] The polishing composition of one embodiment of the present invention contains polyalkylene glycol. If the polishing composition does not contain polyalkylene glycol, there is a risk that the amount of remaining material to be polished, such as polysilicon, will increase. The polyalkylene glycol may be used alone or in combination of two or more. Furthermore, the polyalkylene glycol may be a commercially available product or a synthetic product.

[0046] The type of polyalkylene glycol is not particularly limited, and examples thereof include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyethylene glycol-polypropylene glycol random copolymer, polyethylene glycol-polytetramethylene glycol random copolymer, polypropylene glycol-polytetramethylene glycol random copolymer, polyethylene glycol-polypropylene glycol-polytetramethylene glycol random copolymer, polyethylene glycol-polypropylene glycol block copolymer, polypropylene glycol-polyethylene glycol-polypropylene glycol triblock copolymer, polyethylene glycol-polypropylene glycol-polyethylene glycol triblock copolymer, etc. Among these, from the viewpoint of more effectively reducing the residue of the polishing object to be polished, such as polysilicon, polyethylene glycol and polypropylene glycol are preferred, and polyethylene glycol is more preferred.

[0047] In one embodiment of the present invention, the weight-average molecular weight (Mw) of the polyalkylene glycol is 50 or more, 70 or more, 90 or more, 100 or more, 120 or more, 150 or more, 160 or more, 170 or more, 180 or more, or 190 or more. In one embodiment of the present invention, the weight-average molecular weight (Mw) of the polyalkylene glycol is 2,000 or less, 1,500 or less, 1,000 or less, 800 or less, 700 or less, 600 or less, 500 or less, 400 or less, 300 or less, or 250 or less. In one embodiment of the present invention, the weight-average molecular weight of the polymer compound having an amide bond is, for example, 100 or more to 1,000 or less, 100 or more to 500 or less, or 150 or more to 300 or less. Within such a range, the effect of reducing the amount of the polishing target material, such as polysilicon, remaining while controlling the selectivity is more pronounced.

[0048] In this specification, the weight-average molecular weight of polyalkylene glycol can be measured by gel permeation chromatography (GPC) using polyethylene glycol as a standard substance. The detailed measurement method is as described in the Examples.

[0049] In one embodiment of the present invention, the mass concentration of the polyalkylene glycol in the object to be polished is 1 ppm by mass or more, 2 ppm by mass or more, 4 ppm by mass or more, 6 ppm by mass or more, 8 ppm by mass or more, 10 ppm by mass or more, more than 10 ppm by mass, 15 ppm by mass or more, 20 ppm by mass or more, 25 ppm by mass or more, 30 ppm by mass or more, 35 ppm by mass or more, 40 ppm by mass or more, more than 40 ppm by mass, 60 ppm by mass or more, or 80 ppm by mass or more. In one embodiment of the present invention, the mass concentration of polyalkylene glycol in the polishing object is 1,000 mass ppm or less, 800 mass ppm or less, 600 mass ppm or less, 400 mass ppm or less, 200 mass ppm or less, 150 mass ppm or less, 100 mass ppm or less, less than 100 mass ppm, 80 mass ppm or less, 60 mass ppm or less, 50 mass ppm or less, 40 mass ppm or less, 30 mass ppm or less, 20 mass ppm or less, or 15 mass ppm or less. In one embodiment of the present invention, the mass concentration of polyalkylene glycol in the polishing object is, for example, 1 mass ppm or more to 1,000 mass ppm or less, 4 mass ppm or more to 600 mass ppm or less, 8 mass ppm or more to 400 mass ppm or less, or 10 mass ppm or more to 200 mass ppm or less. Within such a range, the effect of reducing the remaining polishing object, such as polysilicon, is more pronounced.

[0050] [Cellulose derivatives and polymer compounds X] The polishing composition of one embodiment of the present invention contains at least one of a cellulose derivative and a polymer compound X. If the polishing composition does not contain at least one of a cellulose derivative and a polymer compound X, recess formation may be accelerated. The cellulose derivative and polymer compound X may be used alone or in combination of two or more. Furthermore, the cellulose derivative and polymer compound X may be commercially available products or synthetic products.

[0051] (cellulose derivatives) In one embodiment of the present invention, the term "cellulose derivative" refers to a cellulose in which some of the hydroxy groups of the cellulose have been substituted with other different substituents. The cellulose derivatives may be used singly or in combination of two or more. Examples of the cellulose derivatives include cellulose derivatives such as hydroxyethyl cellulose (HEC), hydroxypropyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, ethyl cellulose, ethyl hydroxyethyl cellulose, and carboxymethyl cellulose, as well as pullulan.

[0052] (Polymer compound X) The polymer compound X is represented by the following formula (1):

[0053] [ka]

[0054] In the above formula (1), A is a group selected from at least one of the following:

[0055] [ka]

[0056] 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 R2 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, 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 site. The number of oxygen atoms contained in the ring is, for example, 1 or 2. Furthermore, the polymer compound X is a repeating unit represented by the following formula (2):

[0057] [ka]

[0058] In the above formula (2), A may further contain a repeating unit represented by the following formula: wherein A is a hydroxyl group.

[0059] 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.

[0060] In one embodiment of the present invention, m is 2, 3 or 4.

[0061] 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.

[0062] In one embodiment of the present invention, R 1 and R 2 At least one of the groups is a hydrogen atom.

[0063] 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.

[0064] In one embodiment of the present invention, when polymer compound X contains a repeating unit in which A in formula (1) is represented by at least one of formulas (1-1), (1-2), and (1-3), the repeating unit accounts for 90 mol % or more, or 95 mol % or more (upper limit: 100 mol %), of polymer compound X. Furthermore, when polymer compound X in one embodiment of the present invention contains a repeating unit in which A in formula (1) is represented by formula (1-1), the repeating unit accounts for 90 mol % or more, or 95 mol % or more (upper limit: 100 mol %), of polymer compound X.

[0065] In one embodiment of the present invention, when polymer compound X contains a repeating unit in which A in formula (1) is at least one of formulas (1-1), (1-2), and (1-3) and a repeating unit in formula (2) where A is a hydroxyl group, the total of these repeating units in polymer compound X is 90 mol % or more, or 95 mol % or more (upper limit: 100 mol %). In one embodiment of the present invention, when polymer compound X contains a repeating unit in which A in formula (1) is formula (1-1) and a repeating unit in formula (2) where A is a hydroxyl group, the total of these repeating units in polymer compound X is 90 mol % or more, or 95 mol % or more (upper limit: 100 mol %).

[0066] In one embodiment of the present invention, specific examples of the repeating unit in which A is formula (1-1) (N-vinyl lactam repeating unit) include N-vinyl pyrrolidone (VP), N-vinyl piperidone, N-vinyl caprolactam (VC), etc. In one embodiment of the present invention, a suitable example of a polymer containing an N-vinyl lactam repeating unit is a vinyl pyrrolidone-based polymer.

[0067] Here, the vinylpyrrolidone-based polymer refers to a VP homopolymer or a VP copolymer (for example, a copolymer in which the copolymerization ratio of VP exceeds 20 mol%). An example of a VP copolymer is a copolymer of VP and VA (vinyl alcohol) (PVA-PVP). In a vinylpyrrolidone-based polymer, the proportion of moles of VP units to the total number of moles of repeating units is usually 20 mol% or more, but may be 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%).

[0068] In one embodiment of the present invention, specific examples of the repeating unit in which A is represented by formula (1-2) (repeating unit derived from an α,β-unsaturated amide monomer) 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 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%).

[0069] In one embodiment of the present invention, specific examples of the repeating unit in which A is formula (1-3) (N-vinyl chain amide repeating unit) 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 polymer. Here, a vinylacetamide 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 polymer, 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%).

[0070] In one embodiment of the present invention, the polymer compound X may be polyvinylpyrrolidone, polyacrylamide, poly-N-vinylacetamide, or a copolymer of vinylpyrrolidone and vinyl alcohol (PVP-PVA). Among these, polyvinylpyrrolidone or a copolymer of vinylpyrrolidone and vinyl alcohol (PVP-PVA) is preferred, and polyvinylpyrrolidone is more preferred, from the viewpoint of reducing the amount of the polishing target material, such as polysilicon, remaining while also suppressing recesses.

[0071] In one embodiment of the present invention, the weight average molecular weights of the cellulose derivative and polymer compound X are each independently 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, 200,000 or more, 500,000 or more, or 1,000,000 or more. In one embodiment of the present invention, the weight-average molecular weights of the cellulose derivative and polymer compound X are each independently 2,000,000 or less, 1,500,000 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, 90,000 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 weights of the cellulose derivative and polymer compound X are each independently 1,000 or more and 2,000,000 or less. In one embodiment of the present invention, the weight-average molecular weight of the cellulose derivative may be 500,000 or more and 2,000,000 or less, or 1,000,000 or more and 1,500,000 or less. In one embodiment of the present invention, the weight-average molecular weight of the polymer compound X may be 1,000 or more and 250,000 or less, or 10,000 or more and 100,000 or less, or 20,000 or more and 90,000 or less. Within these ranges, the effect of reducing the amount of the object to be polished, such as polysilicon, remaining and suppressing recesses is more pronounced.

[0072] In one embodiment of the present invention, the mass concentrations of the cellulose derivative and polymer compound X in the object to be polished are each independently 1 ppm by mass or more, 2 ppm by mass or more, 4 ppm by mass or more, 6 ppm by mass or more, 8 ppm by mass or more, 10 ppm by mass or more, more than 10 ppm by mass, 15 ppm by mass or more, 20 ppm by mass or more, 15 ppm by mass or more, 20 ppm by mass or more, 25 ppm by mass or more, 30 ppm by mass or more, 35 ppm by mass or more, or 40 ppm by mass or more. In one embodiment of the present invention, the mass concentrations of the cellulose derivative and polymer compound X in the object to be polished are each independently 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, or 40 ppm by mass or less. In one embodiment of the present invention, the mass concentrations of the cellulose derivative and polymer compound X in the object to be polished are each independently greater than 10 ppm by mass and less than 100 ppm by mass. Within this range, the effects of reducing the amount of remaining material (e.g., polysilicon) on the object to be polished and suppressing recesses are significant. Here, the mass concentration of polymer compound X in the object to be polished refers to the sum of the mass concentrations of the two or more polymer compounds X in the object to be polished when the object to be polished contains two or more polymer compounds X. Furthermore, when the object to be polished contains one type of polymer compound X, it refers to the mass concentration of that one type of polymer compound X in the object to be polished.

[0073] [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, there is a risk that the effects of reducing the amount of the polished object to be polished, such as polysilicon, remaining and suppressing recesses will not be achieved.

[0074] 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.

[0075] 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 reducing the amount of the polishing target material, such as polysilicon, remaining and suppressing recesses is more pronounced.

[0076] 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.

[0077] [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 provide 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.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] [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, or 1900 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, 3000 Å / min or less, 2500 Å / min or less, or 2000 Å / min or less.

[0082] 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 85 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.

[0083] 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 10 Å / min or more, 12 Å / min or more, 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.

[0084] [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.

[0085] 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.

[0086] 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.

[0087] 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 greater than 40, 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 95 or less, 90 or less, 85 or less, 80 or less, 75 or less, or 70 or less.

[0088] [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 residual 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.

[0089] According to one embodiment of the present invention, the transmittance is 0.13% or more, 0.15% or more, 0.2% 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.

[0090] 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.

[0091] [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 %).

[0092] [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.

[0093] 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.

[0094] According to one embodiment of the present invention, the number of silanol groups is 6 / nm 2 More than 22 pieces / nm 2 The composition is substantially composed of the following colloidal silica, an alkali metal salt, a polyalkylene glycol, at least one of a cellulose derivative and a polymer compound X, a preservative, and water, wherein the polymer compound X is represented by the following formula (1):

[0095] [ka]

[0096] In the above formula (1), A is a group selected from at least one of the following:

[0097] [ka]

[0098] 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, it may contain at least one oxygen atom, and in formula 1-1, at least one oxygen atom may be contained in the ring, and the polymer compound X contains a repeating unit represented by the following formula (2):

[0099] [ka]

[0100] The polishing composition may further contain a repeating unit represented by the formula (2), where A is a hydroxyl group, 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, pH, and preservative are applicable. The phrase "essentially composed" will be explained later.

[0101] [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.

[0102] 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.

[0103] 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.

[0104] 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.

[0105] According to one embodiment of the present invention, the polishing composition is substantially free of abrasive grains other than colloidal silica.

[0106] 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.

[0107] According to one embodiment of the present invention, the polishing composition is substantially free of silica having amino groups fixed to the surface thereof.

[0108] According to one embodiment of the present invention, the polishing composition is substantially free of organic acids.

[0109] 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.

[0110] According to one embodiment of the present invention, the polishing composition contains neither carrageenan nor xanthan gum.

[0111] 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.

[0112] In one embodiment of the present invention, the number of silanol groups is 6 / nm 2 More than 22 pieces / nm 2 The composition is substantially composed of the following colloidal silica, an alkali metal salt, a polyalkylene glycol, at least one of a cellulose derivative and a polymer compound X, and water, wherein the polymer compound X is represented by the following formula (1):

[0113] [ka]

[0114] In the above formula (1), A is a group selected from at least one of the following:

[0115] [ka]

[0116] 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, it may contain at least one oxygen atom, and in formula 1-1, at least one oxygen atom may be contained in the ring, and the polymer compound X contains a repeating unit represented by the following formula (2):

[0117] [ka]

[0118] The polishing composition may further contain a repeating unit represented by the formula (2), where A is a hydroxyl group, and has a pH of 9.0 to 11.5. The above explanations regarding colloidal silica, alkali metal salt, polyalkylene glycol, at least one of a cellulose derivative and polymer compound X, water, and pH are applicable. "Substantially composed" means that when the polishing composition contains components other than colloidal silica, alkali metal salt (particularly potassium hydroxide), polyalkylene glycol, at least one of a cellulose derivative and polymer compound X, 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.

[0119] 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.

[0120] <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 polyalkylene glycol (particularly PEG), at least one of a cellulose derivative and a polymer compound X (particularly PVP), water, and an optional preservative. The above explanations regarding the colloidal silica, the alkali metal salt (particularly potassium hydroxide), the polymer 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.

[0121] <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 of the object to be polished, such as polysilicon.

[0122] 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.

[0123] 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.

[0124] 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.

[0125] In one embodiment of the present invention, the polishing conditions are, for example, preferably such that the rotation speeds of the polishing platen and the carrier are each independently 10 to 500 rpm or less. 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.

[0126] 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]

[0127] 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.

[0128] <Production of Polishing Composition> Abrasive grains, an alkali metal salt, a polyalkylene glycol, one of a cellulose derivative and a polymer compound X (described as an additive in Table 1), and water were mixed to prepare a polishing composition having the composition 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 diameter of 90 nm and an average secondary particle diameter of 220 nm, potassium hydroxide, 40 mass ppm of polyvinylpyrrolidone (PVP) (weight average molecular weight 4,5000), 10 mass ppm of polyethylene glycol (PEG) (weight average molecular weight 200), and water, and has a pH of 10.8.

[0129] [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.

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

[0133] <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.

[0134] 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.

[0135] 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.

[0136] 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.

[0137] <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.

[0138] <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.

[0139] <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.

[0140] (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.

[0141] 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 2.

[0142] <Polysilicon recess evaluation> A patterned wafer with a polysilicon film was polished under the following [Condition 1] using the polishing composition shown in Table 1. As shown in Figure 1, the patterned wafer was prepared by laminating a P-TEOS film (1000 Å) or a silicon nitride film (SiN film) 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.

[0143] 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 terminated. In this way, a process of further polishing the first layer (P-TEOS film) after the first layer (P-TEOS film or silicon nitride film (SiN film)) was realized.

[0144] 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). The recess depth thus obtained was evaluated according to the following criteria.

[0145] [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.

[0146] [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 2.

[0147] ◎: Less than 50 nm ○: 50nm or more and less than 75nm △: 75nm or more and less than 100nm ×: 100 nm or more.

[0148] <Remaining polysilicon (polishing residue)> The thickness of the polysilicon remaining on the P-TEOS film after polishing was measured using an optical film thickness measuring device (ASET-f5x, manufactured by KLA-Tencor Corporation). The film thickness at this point was taken as the unpolished portion and was evaluated according to the following four-level evaluation criteria. △× indicates that it is not acceptable for practical use. The results are shown in Table 2.

[0149] ◎: Less than 5Å ○: 5 Å or more and less than 10 Å △: 10 Å or more and less than 20 Å ×: 20 Å or more.

[0150] [Metal impurity measurement (atom count 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 surface were measured using a total reflection X-ray fluorescence spectrometer (TREX-610T) manufactured by Technos Corporation. The results are shown in Table 2.

[0151] [Table 1]

[0152] [Table 2]

[0153] <Consideration> The polishing compositions of the examples reduce the amount of polysilicon remaining after polishing and also reduce the amount of resilience of the polished surface. In contrast, with the polishing compositions of the comparative examples, polysilicon to be polished remained or recessing was promoted, as shown in FIGS.

[0154] Comparing Examples 1 to 3, it is found that the mass concentration of polyalkylene glycol in the polishing composition is preferably 40 ppm or more from the viewpoint of suppressing polysilicon residue. Comparing Example 2 with Example 4, it is found that, among polyalkylene glycols, PEG is preferable from the viewpoint of suppressing polysilicon residue. Comparing Example 2 with Example 5, it is found that PVP is more preferable than HEC from the viewpoint of suppressing polysilicon residue and the occurrence of recesses. Comparing Example 2 with Example 6, it is found that, among polymer compounds X, PVP is preferable from the viewpoint of suppressing recesses. Comparing Example 2 with Examples 7 and 8, it is found that, from the viewpoint of suppressing polysilicon residue and the occurrence of recesses, the number of silanol groups of colloidal silica is 6.6 / nm 2 Super 17.5 pieces / nm 2 It can be seen that it is preferable that the pH of the polishing composition is less than 10.0. Furthermore, comparing Example 2 with Examples 9 and 10, it can be seen that from the viewpoint of suppressing the remaining polysilicon, the pH of the polishing composition is preferably greater than 10.0. Furthermore, comparing Example 2 with Examples 11 to 13, it can be seen that from the viewpoint of reducing the amount of remaining metal, an alkali metal hydroxide is more preferable than an alkali metal carbonate as the alkali metal salt. Furthermore, it can be seen that potassium is particularly preferable as the alkali metal from the viewpoint of reducing the amount of remaining metal. Furthermore, comparing Example 2 with Example 14, it can be seen that from the viewpoint of suppressing the occurrence of recesses, the pH of the polishing composition is preferably less than 11.2.

[0155] In contrast, none of the polishing compositions of the comparative examples achieves both a reduction in the amount of remaining polysilicon to be polished and the prevention of recesses. More specifically, the results of Comparative Example 1 show that the absence of either one of the cellulose derivative and polymer compound X (additive) and polyalkylene glycol increases the occurrence of recesses. Furthermore, the results of Comparative Examples 2 to 4 show that the absence of polyalkylene glycol increases the amount of remaining polysilicon. Furthermore, the results of Comparative Example 5 show that the absence of at least one of the cellulose derivative and polymer compound X increases the occurrence of recesses. Furthermore, the results of Comparative Examples 6 to 12 and 14 show that the absence of at least one of the cellulose derivative and polymer compound X increases the occurrence of recesses when the number of silanol groups in the colloidal silica is 6 / nm 2 Furthermore, it can be seen from the results of Comparative Example 13 that when the number of silanol groups in the colloidal silica is less than 22 / nm 2 It can be seen that when the pH of the polishing composition is above 9.0, the occurrence of recesses increases. In addition, the results of Comparative Example 15 show that when the pH of the polishing composition is less than 9.0, the amount of residual polysilicon increases. [Explanation of symbols]

[0156] 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. a solution containing colloidal silica, an alkali metal salt, a polyalkylene glycol, at least one of a cellulose derivative and a polymer compound X, and water, and having a pH of 9.0 to 11.5; The polymer compound X 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, it may contain at least one oxygen atom, and in formula 1-1, it may contain at least one oxygen atom in the ring, The polymer compound X is represented by the following formula (2): 【Transformation 3】 In the above formula (2), A is a hydroxyl group, and the repeating unit may further contain the following repeating unit: (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. 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.

3. 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.

4. 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.

5. 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.

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

7. 7. The polishing composition according to claim 6, wherein the alkali metal hydroxide is potassium hydroxide.

8. 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%.

9. 6 silanol groups / nm ２ More than 22 pieces / nm ２ The composition is substantially composed of the following colloidal silica, an alkali metal salt, a polyalkylene glycol, at least one of a cellulose derivative and a polymer compound X, and water: The polymer compound X is represented by the following formula (1): 【Chemistry 4】 In the above formula (1), A is a group selected from at least one of the following: 【Transformation 5】 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, it may contain at least one oxygen atom, and in formula 1-1, it may contain at least one oxygen atom in the ring, The polymer compound X is represented by the following formula (2): 【Transformation 6】 The polishing composition may further contain a repeating unit represented by the formula (2), wherein A is a hydroxyl group, and has a pH of 9.0 to 11.

5.

10. 6 silanol groups / nm ２ More than 22 pieces / nm ２ The composition is substantially composed of the following colloidal silica, an alkali metal salt, a polyalkylene glycol, at least one of a cellulose derivative and a polymer compound X, a preservative, and water: The polymer compound X is represented by the following formula (1): 【Transformation 7】 In the above formula (1), A is a group selected from at least one of the following: 【Transformation 8】 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, it may contain at least one oxygen atom, and in formula 1-1, it may contain at least one oxygen atom in the ring, The polymer compound X is represented by the following formula (2): 【Chemistry 9】 The polishing composition may further contain a repeating unit represented by the formula (2), wherein A is a hydroxyl group, and has a pH of 9.0 to 11.5.

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