Polishing liquid composition for silicon substrate

Abstract

To provide a polishing liquid composition for silicon substrates that can both improve polishing speed and storage stability of the concentrate, a method for polishing silicon substrates using the composition, and a method for manufacturing semiconductor substrates.SOLUTION: A polishing liquid composition for silicon substrates includes silica particles, a water-soluble polymer having an amino group to which a hydroxyalkyl group is attached, and water. In a silicon substrate polishing method in which the silicon substrate finishing and polishing steps 1 and 2 are performed in this order, the silicon substrate is polished in the finishing and polishing step 1 using this polishing liquid composition for silicon substrates. In the finishing and polishing step 2, the silicon substrate is polished using a polishing liquid composition containing silica particles and water-soluble polymers.SELECTED DRAWING: None

Description

Technical Field

[0001] The present disclosure relates to a polishing liquid composition for a silicon substrate, a polishing method using the same, and a method for manufacturing a semiconductor substrate.

Background Art

[0002] As a polishing liquid composition used for polishing a silicon substrate used in the manufacture of a semiconductor substrate, a polishing liquid composition containing silica particles is known. In this type of polishing liquid composition, the occurrence of surface defects (LPD: Light point defects) of the silicon substrate due to the aggregation of silica particles and the clogging of the filter when filtering the polishing liquid composition to remove aggregates have become problems (see, for example, Patent Document 1). Further, for the purpose of improving the surface quality of the substrate after polishing, a polishing liquid composition containing a water-soluble polymer is known (see Patent Documents 2 and 3).

[0003] In Patent Document 1, a polishing liquid composition containing an abrasive such as silica particles and a polymer having a structural unit derived from a 2-oxazoline-based compound or a 2-oxazine-based compound has been proposed. In Patent Document 2, a polishing liquid composition containing abrasive grains, a basic compound, and a cationic water-soluble polymer containing a nitrogen-containing group (for example, polyethyleneimine) has been proposed. In Patent Document 3, a polishing composition used for polishing in the stage before final polishing (intermediate polishing), which contains abrasive grains such as silica particles, a basic compound, and a water-soluble polymer having a weight average molecular weight of 30×10 4 a higher water-soluble polymer (for example, hydroxyethyl cellulose), and a dispersant has been proposed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

[0005] However, the polishing speed is not sufficient when using the polishing liquid compositions described in Patent Documents 1 and 3. When using the polishing liquid composition described in Patent Document 2, silica particles aggregate due to the cationic water-soluble polymer containing nitrogen groups, which leads to a deterioration of the surface condition of the silicon substrate, such as the generation of scratches. Furthermore, polishing fluid compositions are typically stored and transported in a concentrated state, and therefore storage stability in this concentrated form is also required.

[0006] This disclosure provides a polishing liquid composition for silicon substrates that can achieve both improved polishing speed and storage stability of the concentrate, a method for polishing silicon substrates using the same, and a method for manufacturing semiconductor substrates. [Means for solving the problem]

[0007] This disclosure relates, in one embodiment, to a polishing liquid composition for silicon substrates comprising silica particles (component A), a water-soluble polymer having an amino group to which a hydroxyalkyl group is bonded (component B), and water.

[0008] This disclosure relates, in one embodiment, to a method for polishing a silicon substrate, which includes the step of polishing the silicon substrate to be polished using the polishing liquid composition of this disclosure.

[0009] This disclosure relates to a method for polishing a silicon substrate, comprising a finishing polishing step 2 for performing a final polish on the silicon substrate and a finishing polishing step 1 which is a polishing step preceding the finishing polishing step 2, wherein the finishing polishing step 1 and the finishing polishing step 2 are performed in this order, and in the finishing polishing step 1, the polishing is performed using the polishing liquid composition of this disclosure, and in the finishing polishing step 2, the polishing is performed using the polishing liquid composition containing silica particles and a water-soluble polymer.

[0010] This disclosure relates, in one embodiment, to a method for manufacturing a semiconductor substrate, which includes performing the polishing method described herein. [Effects of the Invention]

[0011] This disclosure provides a polishing liquid composition for silicon substrates that can achieve both improved polishing speed and storage stability of the concentrate, a method for polishing a silicon substrate using the polishing liquid composition, and a method for manufacturing a semiconductor substrate. [Modes for carrying out the invention]

[0012] This disclosure is based on the finding that by using a polishing solution composition for silicon substrates containing silica particles and a specific amino group-containing water-soluble polymer, silicon substrates can be polished at high speed and the concentrated product exhibits excellent storage stability.

[0013] In other words, the present disclosure relates, in one embodiment, to a polishing liquid composition for silicon substrates (hereinafter also referred to as "the polishing liquid composition of the present disclosure") which contains silica particles (component A), a water-soluble polymer having an amino group to which a hydroxyalkyl group is bonded (component B), and water.

[0014] According to this disclosure, in one or more embodiments, a polishing liquid composition for silicon substrates can be provided that can achieve both improved polishing speed and storage stability of the concentrate.

[0015] Although the details of the mechanism of action of this disclosure are not clear, it is presumed to be as follows. Under alkaline polishing conditions, both silica particles and the silicon substrate being polished have a negative charge, resulting in electrostatic repulsion. Therefore, it is difficult for silica particles to approach the silicon substrate, and the polishing speed is not sufficiently achieved. On the other hand, cationic polymers (e.g., polyethyleneimine) blended into the polishing solution reduce the negative charge of both the silica particles and the silicon substrate, and the cationic polymer itself acts as a binder, promoting the approach of silica particles to the silicon substrate and thus improving the polishing speed. However, since cationic polymers such as polyethyleneimine also act as a binder between silica particles, the silica particles tend to aggregate, and in concentrated solutions with high silica concentrations, silica precipitation occurs. In this disclosure, a water-soluble polymer having an amino group bonded to a hydroxyalkyl group, that is, a cationic polymer with steric repulsion groups on the amino group, is incorporated into the polishing solution. This retains the effect of reducing the negative charge of silica abrasive grains and silicon substrates, while also exhibiting an effect of promoting the approach of silica particles (i.e., an effect of improving polishing speed). Furthermore, because the cationic polymer covering the surface of the silica particles has steric repulsion groups, it also has the effect of mitigating aggregation between silica particles. Therefore, it is believed that aggregation of silica particles can be suppressed, and both improved polishing speed and storage stability of the concentrate can be achieved. However, this disclosure does not have to be construed as being limited to these mechanisms.

[0016] [Polished silicon substrate] The polishing liquid composition of this disclosure is a polishing composition for silicon substrates and can be used, for example, in a polishing step for polishing a silicon substrate to be polished in a semiconductor substrate manufacturing method, or in a polishing step for polishing a silicon substrate to be polished in a silicon substrate polishing method. Examples of silicon substrates to be polished using the polishing liquid composition of this disclosure include, in one or more embodiments, silicon substrates, etc., and in one or more embodiments, single crystal silicon substrates, polysilicon substrates, substrates having a polysilicon film, SiN substrates, etc., and from the viewpoint of exhibiting the effects of the polishing liquid composition of this disclosure, single crystal silicon substrates or polysilicon substrates are preferred, and single crystal silicon substrates are more preferred.

[0017] [Silica particles (Component A)] The polishing liquid composition of the present disclosure contains silica particles (hereinafter also referred to as "Component A") as an abrasive. Examples of Component A include colloidal silica, fumed silica, pulverized silica, or silica obtained by surface-modifying them. From the viewpoints of achieving both an improvement in polishing rate and storage stability of the concentrate, suppressing aggregation of silica particles, and improving surface quality such as reduction of surface roughness (haze), surface defects (LPD), and scratches, colloidal silica is preferred. Component A may be one type or a combination of two or more types.

[0018] As a form of use of Component A, a slurry form is preferred from the viewpoint of operability. When Component A contained in the polishing liquid composition of the present disclosure is colloidal silica, from the viewpoint of preventing contamination of the silicon substrate by alkali metals, alkaline earth metals, etc., it is preferable that the colloidal silica is obtained from a hydrolyzate of an alkoxysilane. Silica particles obtained from a hydrolyzate of an alkoxysilane can be produced by a conventionally known method.

[0019] From the viewpoint of maintaining the polishing rate, the average primary particle size of Component A is preferably 10 nm or more, more preferably 20 nm or more, still more preferably 30 nm or more, and from the viewpoint of improving surface quality such as reduction of surface roughness (haze), surface defects (LPD), and scratches, it is preferably 50 nm or less, more preferably 45 nm or less, still more preferably 40 nm or less. More specifically, the average primary particle size of Component A is preferably 10 nm or more and 50 nm or less, more preferably 20 nm or more and 45 nm or less, still more preferably 30 nm or more and 40 nm or less. In the present disclosure, the average primary particle size of Component A is calculated using the specific surface area S (m 2 / g) calculated by the nitrogen adsorption method (BET method). The value of the average primary particle size is the value measured by the method described in the examples.

[0020] From the viewpoint of maintaining polishing speed, the average secondary particle diameter of component A is preferably 20 nm or more, more preferably 30 nm or more, even more preferably 40 nm or more, and even more preferably 60 nm or more. From the viewpoint of improving surface quality such as reducing surface roughness (haze), surface defects (LPD), and scratches, it is preferably 100 nm or less, more preferably 90 nm or less, and even more preferably 80 nm or less. Similarly, from the viewpoint of improving surface quality such as reducing surface roughness (haze), surface defects (LPD), and scratches, the average secondary particle diameter of component A is preferably 20 nm or more and 100 nm or less, more preferably 40 nm or more and 90 nm or less, and even more preferably 60 nm or more and 80 nm or less. In this disclosure, the average secondary particle diameter is a value measured by dynamic light scattering (DLS) and is a value measured by the method described in the examples.

[0021] The degree of association of component A is preferably 3 or less, more preferably 2.5 or less, and even more preferably 2.3 or less, from the viewpoint of improving surface quality such as reducing surface roughness (haze), surface defects (LPD), and scratches. From the viewpoint of improving polishing speed and surface quality, it is preferably 1.1 or more, more preferably 1.5 or more, and even more preferably 1.8 or more.

[0022] In this disclosure, the degree of association of component A is a coefficient representing the shape of silica particles, and is calculated by the following formula. Degree of association = average secondary particle size / average primary particle size

[0023] As a method for adjusting the degree of association of component A, for example, the methods described in Japanese Patent Publication No. 6-254383, Japanese Patent Publication No. 11-214338, Japanese Patent Publication No. 11-60232, Japanese Patent Publication No. 2005-060217, Japanese Patent Publication No. 2005-060219, etc., can be employed.

[0024] From the viewpoint of improving polishing speed and surface quality, the shape of component A is preferably a so-called spherical and / or so-called cocoon shape.

[0025] The content of component A in the polishing liquid composition of this disclosure is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and even more preferably 0.3% by mass or more, in terms of SiO2, from the viewpoint of improving the polishing speed. From the viewpoint of suppressing the aggregation of silica particles, from the viewpoint of storage stability of the concentrate, and from the viewpoint of improving surface quality, it is preferably 5% by mass or less, more preferably 2.5% by mass or less, and even more preferably 1% by mass or less. Therefore, the content of component A in the polishing liquid composition of this disclosure is preferably 0.1% by mass or more and 5% by mass or less, more preferably 0.2% by mass or more and 2.5% by mass or less, and even more preferably 0.3% by mass or more and 1% by mass or less. When component A is a combination of two or more types, the content of component A refers to the total content of those types.

[0026] [Water-soluble polymer having an amino group bonded to a hydroxyalkyl group (component B)] The polishing liquid composition of this disclosure contains a water-soluble polymer having an amino group to which a hydroxyalkyl group is bonded (hereinafter also referred to as "component B"). In one or more embodiments, component B is an amino group-containing water-soluble polymer having an amino group to which a nitrogen atom is bonded in the main chain and a hydroxyalkyl group is bonded to the nitrogen atom of the main chain. In one or more embodiments, component B is an amino group-containing water-soluble polymer having at least one amino group, and to which a hydroxyalkyl group is bonded to the nitrogen atom of at least some of the total amino groups. In this disclosure, "water-soluble" means having a solubility of 0.5 g / 100 mL or more, preferably 2 g / 100 mL or more, in water (20°C). In one or more embodiments, the hydroxyalkyl group is preferably a hydroxyalkyl group having 1 to 5 carbon atoms, more preferably a hydroxyalkyl group having 1 to 3 carbon atoms, from the viewpoint of achieving both improved polishing speed and storage stability of the concentrate. Examples include hydroxymethyl group, hydroxyethyl group, hydroxypropyl group, hydroxybutyl group, propanediol group, etc. In one or more embodiments, the amino group to which the hydroxyalkyl group is bonded is an amino group having a steric repulsion group, and from the viewpoint of achieving both improved polishing speed and storage stability of the concentrate, it is preferable that it is a modifying group of the amino group by an epoxide. In one or more embodiments, the modifying group is a group formed by the reaction of an amino group and an epoxide. In one or more embodiments, at least some of the amino groups of the total amino groups of component B are modified by the epoxide to become amino groups having steric repulsion. From the viewpoint of achieving both improved polishing speed and storage stability of the concentrate, ethylene oxide (EO), propylene oxide (PO), and glycidol derivatives are preferred as epoxides, propylene oxide (PO) or glycidol derivatives are more preferred, and propylene oxide (PO) is even more preferred. Examples of glycidol derivatives include glycidol and alkylglycidyl ethers, and glycidol is preferred from the viewpoint of availability, achieving both improved polishing speed and storage stability of the concentrate, and suppressing aggregation of silica particles. From the viewpoint of availability, the alkyl group of alkyl glycidyl ether is preferably an alkyl group having 1 to 8 carbon atoms, such as a methyl group, ethyl group, propyl group, butyl group, or 2-ethylhexyl group. Specific examples of alkyl glycidyl ethers include methyl glycidyl ether and 2-ethylhexyl glycidyl ether.

[0027] Component B can be obtained in one or more embodiments by reacting a water-soluble polymer having a primary or secondary amino group with an epoxy. Examples of water-soluble polymers having a primary or secondary amino group include polyethyleneimine, polyallylamine, and polydiallylamine.

[0028] In one or more embodiments, component B is preferably an amino group-containing water-soluble polymer having a structure represented by the following formula (1), from the viewpoint of achieving both improved polishing speed and storage stability of the concentrate. [ka] In formula (1) above, R represents a hydrogen atom, a methyl group, or a hydroxymethyl group. From the viewpoint of achieving both improved polishing speed and storage stability of the concentrate, and from the viewpoint of suppressing aggregation of silica particles, R is preferably a methyl group or a hydroxymethyl group, and more preferably a methyl group.

[0029] In one or more embodiments, component B is preferably an amino group-containing water-soluble polymer in which at least some of the amino groups of a water-soluble polymer having a primary amino group or a secondary amino group are modified with epoxy, from the viewpoint of achieving both improved polishing speed and storage stability of the concentrate.

[0030] The ratio of primary and secondary amino groups in the total amino groups of component B is preferably 50% or less, more preferably 40% or less, even more preferably 30% or less, even more preferably 20% or less, even more preferably 10% or less, even more preferably 5% or less, even more preferably 1% or less, and even more preferably 0%, from the viewpoint of achieving both improved polishing speed and storage stability of the concentrate, and from the viewpoint of suppressing the aggregation of silica particles. The ratio of primary and secondary amino groups in the total amino groups of component B can be measured, for example, by the method described in the examples.

[0031] Examples of component B include polyethyleneimine containing the composition of formula (1) above, a reaction product of propylene oxide (PO) and polyethyleneimine, and a reaction product of glycidol and polyethyleneimine.

[0032] The weight-average molecular weight of component B is preferably 200 or more, more preferably 800 or more, even more preferably 1,000 or more, even more preferably 1,500 or more, and even more preferably 2,000 or more, from the viewpoint of achieving both improved polishing speed and storage stability of the concentrate, from the viewpoint of suppressing the aggregation of silica particles, and from the viewpoint of improving surface quality, it is preferably 200,000 or less, more preferably 100,000 or less, even more preferably 50,000 or less, even more preferably 30,000 or less, even more preferably 20,000 or less, even more preferably 15,000 or less, and even more preferably 12,000 or less. More specifically, the weight-average molecular weight of component B is preferably 200 to 200,000, more preferably 800 to 100,000, even more preferably 1,000 to 50,000, even more preferably 1,500 to 30,000, even more preferably 2,000 to 20,000, even more preferably 2,000 to 15,000, and even more preferably 2,000 to 12,000. The weight-average molecular weight of component B in this disclosure can be measured, for example, by the method described in the examples.

[0033] From the viewpoint of improving polishing speed, the content of component B in the polishing liquid composition of this disclosure is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, and even more preferably 0.008% by mass or more. From the viewpoint of suppressing the aggregation of silica particles and the storage stability of the concentrate, it is preferably 0.1% by mass or less, more preferably 0.05% by mass or less, even more preferably 0.03% by mass or less, and even more preferably 0.02% by mass or less. More specifically, the content of component B is preferably 0.001% by mass or more and 0.1% by mass or less, more preferably 0.005% by mass or more and 0.05% by mass or less, even more preferably 0.008% by mass or more and 0.03% by mass or less, and even more preferably 0.008% by mass or more and 0.02% by mass or less.

[0034] The ratio of the content of component B to the content of component A in the polishing liquid composition of this disclosure (mass ratio B / A) is preferably 0.002 or higher, more preferably 0.01 or higher, and even more preferably 0.014 or higher from the viewpoint of improving the polishing speed, and preferably 0.1 or lower, more preferably 0.06 or lower, and even more preferably 0.04 or lower from the viewpoint of suppressing the aggregation of silica particles and the storage stability of the concentrate. More specifically, the mass ratio B / A is preferably 0.002 or higher and 0.1 or lower, more preferably 0.01 or higher and 0.06 or lower, and even more preferably 0.014 or higher and 0.04 or lower.

[0035] [water] The polishing fluid composition of this disclosure may contain water in one or more embodiments. Examples of water include deionized water and ultrapure water. The amount of water in the polishing fluid composition of this disclosure may be, for example, the remainder of component A, component B, and any optional component described later.

[0036] [Nitrogen-containing basic compound (component C)] In one or more embodiments, the polishing liquid composition of this disclosure preferably further contains a nitrogen-containing basic compound (hereinafter also referred to as "component C") from the viewpoint of adjusting the pH. Component C is preferably a water-soluble nitrogen-containing basic compound from the viewpoint of achieving both improved polishing speed and storage stability of the concentrate, and from the viewpoint of suppressing the aggregation of silica particles. In this disclosure, "water-soluble" means having a solubility of 0.5 g / 100 mL or more, preferably 2 g / 100 mL or more, in water (20°C). In this disclosure, "water-soluble nitrogen-containing basic" means a nitrogen-containing compound that exhibits basicity when dissolved in water. In one or more embodiments, component C does not contain an amino group-containing water-soluble polymer (component B). Component C may be one type or a combination of two or more types.

[0037] Component C may be at least one selected from amine compounds and ammonium compounds in one or more embodiments. Examples of component C may be one or more combinations selected from ammonia, ammonium hydroxide, ammonium carbonate, ammonium bicarbonate, dimethylamine, trimethylamine, diethylamine, triethylamine, monoethanolamine, diethanolamine, triethanolamine, N-methylethanolamine, N-methyl-N,N-diethanolamine, N,N-dimethylethanolamine, N,N-diethylethanolamine, N,N-dibutylethanolamine, N-(β-aminoethyl)ethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, ethylenediamine, hexamethylenediamine, piperazine hexahydrate, anhydrous piperazine, 1-(2-aminoethyl)piperazine, N-methylpiperazine, diethylenetriamine, tetramethylammonium hydroxide, and hydroxyamine. In particular, from the viewpoint of achieving both improved polishing speed and storage stability of the concentrate, and from the viewpoint of suppressing aggregation of Syrian particles, ammonia or a mixture of ammonia and hydroxyamine is preferred as component C, with ammonia being more preferred.

[0038] If the polishing fluid composition of this disclosure contains component C, the content of component C in the polishing fluid composition of this disclosure is preferably 0.0005% by mass or more, more preferably 0.001% by mass or more, and still preferably 0.002% by mass or more, from the viewpoint of achieving both improved polishing speed and storage stability of the concentrate, and from the viewpoint of suppressing aggregation of silica particles. From a similar viewpoint, it is preferably 0.05% by mass or less, more preferably 0.03% by mass or less, still preferably 0.015% by mass or less, and still preferably 0.01% by mass or less. From a similar viewpoint, the content of component C in the polishing fluid composition of this disclosure is preferably 0.0005% by mass or more and 0.05% by mass or less, more preferably 0.001% by mass or more and 0.03% by mass or less, still preferably 0.002% by mass or more and still preferably 0.002% by mass or more and still preferably 0.01% by mass or less. If component C is a combination of two or more types, the content of component C refers to the total content of those types.

[0039] When the polishing fluid composition of this disclosure contains component C, the ratio C / A (mass ratio C / A) of the content of component C to the content of component A in the polishing fluid composition of this disclosure is preferably 0.001 or higher, more preferably 0.002 or higher, and even more preferably 0.004 or higher, from the viewpoint of achieving both improved polishing speed and storage stability of the concentrate, and from the viewpoint of suppressing the aggregation of silica particles. From the same viewpoint, it is preferably 0.1 or lower, more preferably 0.06 or lower, and even more preferably 0.02 or lower. More specifically, the mass ratio C / A in the polishing fluid composition of this disclosure is preferably 0.001 or higher and 0.1 or lower, more preferably 0.002 or higher and 0.06 or lower, and even more preferably 0.004 or higher and 0.02 or lower.

[0040] [Other ingredients] The polishing fluid compositions of this disclosure may further contain other components, to the extent that the effects of this disclosure are not impaired. Examples of other components in one or more embodiments include water-soluble polymers other than component B, pH adjusters other than component C, preservatives, alcohols, chelating agents, and oxidizing agents.

[0041] [pH] The pH of the polishing liquid composition of this disclosure is preferably greater than 8.5, more preferably 9 or greater, and even more preferably 9.3 or greater, from the viewpoint of achieving both improved polishing speed and storage stability of the concentrate, and from the viewpoint of suppressing the aggregation of silica particles. From the same viewpoint, it is preferably 14 or less, more preferably 13 or less, even more preferably 12.5 or less, even more preferably 12 or less, even more preferably 11.5 or less, and even more preferably 11 or less. More specifically, the pH of the polishing liquid composition of this disclosure is preferably greater than 8.5 and 14 or less, more preferably 9 and 13 or less, even more preferably 9 and 12.5 or less, even more preferably 9 and 12 or less, even more preferably 9.3 and 11.5 or less, and even more preferably 9.3 and 11 or less. The pH of the polishing liquid composition of this disclosure can be adjusted using component C or known pH adjusting agents. In this disclosure, the above pH is the pH of the polishing liquid composition at 25°C and can be measured using a pH meter. The above pH can be, for example, the value measured by the method described in the examples.

[0042] The polishing fluid composition of this disclosure can be produced, for example, by blending components A and B with water and optionally the aforementioned optional components (component C and other components) in a known manner. That is, the polishing fluid composition of this disclosure can be produced, for example, by blending at least component A, component B and water. Accordingly, in other embodiments, this disclosure relates to a method for producing a polishing fluid composition, which includes a step of blending at least component A, component B and water. In this disclosure, "blending" includes mixing component A, component B, water, and optionally the optional components (component C and other components) simultaneously or in any order. The blending can be carried out, for example, using a stirrer such as a homomixer, homogenizer, ultrasonic disperser, wet ball mill, or bead mill. The preferred blending amounts of each component in the method for producing the polishing fluid composition of this disclosure can be the same as the preferred content of each component in the polishing fluid composition of this disclosure described above.

[0043] In this disclosure, "content of each component in the polishing liquid composition" means the content of each component at the time of use, that is, at the time when the polishing liquid composition is first used for polishing.

[0044] The polishing fluid composition of this disclosure may be manufactured as a concentrate and diluted at the time of use, from the viewpoint of storage and transportation. The dilution ratio is preferably 2 times or more, more preferably 5 times or more, even more preferably 10 times or more, and even more preferably 15 times or more, from the viewpoint of manufacturing and transportation costs and storage stability of the concentrate, and preferably 40 times or less, more preferably 30 times or less, and even more preferably 20 times or less, from the viewpoint of storage stability of the concentrate. The concentrate of the polishing fluid composition of this disclosure can be used after being diluted with water so that the content of each component at the time of use is as described above (i.e., the content at the time of use). In this disclosure, "at the time of use" of the concentrate of the polishing fluid composition means the state in which the concentrate of the polishing fluid composition has been diluted.

[0045] In one or more embodiments, the polishing fluid composition of this disclosure is preferably used for finish polishing in a multi-stage polishing process of a silicon substrate, from the viewpoint of achieving both improved polishing speed and improved surface quality. In one or more embodiments, the polishing liquid composition of this disclosure is preferably used in the polishing stage preceding the final polishing in a multi-stage polishing of a silicon substrate, from the viewpoint of achieving both improved polishing speed and improved surface quality. In one or more embodiments, the polishing stage preceding the final polishing includes a final polishing step 2 in which the silicon substrate is performed to finish polishing, and a final polishing step 1 which is a polishing step preceding the final polishing step 2, and the final polishing step 1 and the final polishing step 2 are performed in this order, and the final polishing step 1 is an example of a final polishing step 1 in a silicon substrate polishing method.

[0046] [Polishing solution kit] This disclosure relates, in one embodiment, to a polishing fluid kit for producing the polishing fluid composition of this disclosure (hereinafter also referred to as the "kit of this disclosure"). According to the kit of this disclosure, a polishing fluid composition that can achieve both improved polishing speed and storage stability of the concentrate can be obtained. Examples of the kits of this disclosure include polishing solution kits containing a solution comprising component A and component B in one or more embodiments. The solution may optionally contain the above-mentioned optional components (component C, other components). The solution may be diluted with water as needed before use.

[0047] [Method for polishing silicon substrates] This disclosure relates, in one embodiment, to a method for polishing a silicon substrate (hereinafter also referred to as "the polishing method of this disclosure") which includes a step of polishing the silicon substrate to be polished using the polishing liquid composition of this disclosure (hereinafter also referred to as "the polishing step"). The polishing method of this disclosure, by using the polishing fluid composition of this disclosure, makes it possible to achieve both improved polishing speed and storage stability of the concentrate. Furthermore, the polishing method of this disclosure makes it possible to improve surface quality, such as reducing surface roughness (haze), surface defects (LPD), and scratches.

[0048] In the polishing step of the polishing method of this disclosure, for example, the silicon substrate to be polished can be pressed against a surface plate to which a polishing pad is attached, and the silicon substrate to be polished can be polished with a polishing pressure of 3 to 20 kPa. In this disclosure, polishing pressure refers to the pressure of the surface plate applied to the surface of the silicon substrate to be polished during polishing.

[0049] In the polishing step of the polishing method of this disclosure, for example, the silicon substrate to be polished can be pressed against a surface plate to which a polishing pad is attached, and the silicon substrate to be polished can be polished with a polishing liquid composition and a polishing pad surface temperature of 15°C to 40°C. From the viewpoint of achieving both improved polishing speed and reduced surface roughness (haze), the temperature of the polishing liquid composition and the polishing pad surface temperature are preferably 15°C or higher or 20°C or higher, and preferably 40°C or lower or 30°C or lower.

[0050] In the polishing method of this disclosure, the polishing step is preferably a finishing polishing step in one or more embodiments, from the viewpoint of achieving both improved polishing speed and storage stability of the concentrate.

[0051] In the polishing method of this disclosure, the polishing step is preferably a step preceding the finish polishing step, from the viewpoint of achieving both improved polishing speed and storage stability of the concentrate, and from the viewpoint of improving surface quality, in one or more embodiments. In one or more embodiments, the polishing process preceding the final polishing process includes a final polishing process 2 for performing the final polishing of the silicon substrate and a final polishing process 1 which is a polishing process preceding the final polishing process 2, and the final polishing process 1 and the final polishing process 2 are performed in this order. From the viewpoint of achieving both improved polishing speed and storage stability of the concentrate, and from the viewpoint of improving surface quality, it is preferable that the final polishing process 1 and the final polishing process 2 are consecutive polishing processes in one or more embodiments. From the viewpoint of achieving both improved polishing speed and storage stability of the concentrate, and from the viewpoint of improving surface quality, it is preferable to use the polishing liquid composition of this disclosure in the finishing polishing step 1, and to use a polishing liquid composition containing water-soluble polymers such as silica particles and HEC in the finishing polishing step 2. Examples of water-soluble polymers to be included in the polishing liquid composition used in the finishing polishing step 2 include hydroxyethylcellulose (HEC), polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), and polyethylene glycol (PEG). As for the polishing liquid composition used in the finishing polishing step 2, conventional polishing liquid compositions for finishing polishing can be used. In other words, in one embodiment, the present disclosure is a method for polishing a silicon substrate, comprising a finishing polishing step 2 for performing a finishing polish on the silicon substrate, and a finishing polishing step 1 which is a polishing step preceding the finishing polishing step 2, wherein the finishing polishing step 1 and the finishing polishing step 2 are performed in this order. In the finishing polishing step 1, polishing is performed using the polishing liquid composition of this disclosure. The present invention relates to a method for polishing a silicon substrate, in which the finishing polishing step 2 is performed using a polishing liquid composition containing silica particles and a water-soluble polymer. The polishing conditions for finishing polishing steps 1 and 2 are the same as those for the polishing steps in the polishing method of this disclosure described above. Finish polishing steps 1 and 2 can be performed on the same polishing plate. Alternatively, finish polishing steps 1 and 2 can be performed on different polishing plates; that is, finish polishing step 2 can be performed on a different polishing plate than the one used in finish polishing step 1.

[0052] [Manufacturing method for semiconductor substrates] This disclosure relates in one embodiment to a method for manufacturing a semiconductor substrate (hereinafter also referred to as the "semiconductor substrate manufacturing method of this disclosure") which includes performing the polishing method of this disclosure. In one or more embodiments, the semiconductor substrate manufacturing method of this disclosure may include a step of polishing a silicon substrate to be polished using the polishing liquid composition of this disclosure (hereinafter also referred to as the "polishing step") and a step of cleaning the polished silicon substrate (hereinafter also referred to as the "cleaning step"). According to the semiconductor substrate manufacturing method of this disclosure, by using the polishing solution composition of this disclosure, it is possible to achieve both improved polishing speed and storage stability of the concentrate, thereby enabling the production of high-quality semiconductor substrates in high yield, with good productivity, and at low cost.

[0053] The polishing step in the semiconductor substrate manufacturing method of this disclosure may include, for example, a lapping (rough polishing) step to flatten a single-crystal silicon substrate obtained by slicing a single-crystal silicon ingot into a thin disc shape, and a finish polishing step to mirror-finish the surface of the single-crystal silicon substrate after etching the lapped single-crystal silicon substrate. From the viewpoint of achieving both improved polishing speed and improved surface quality, the polishing liquid composition of this disclosure is preferably used in the finish polishing step in one or more embodiments.

[0054] The polishing step in the semiconductor substrate manufacturing method of this disclosure may include, for example, a step of flattening a substrate on which a polysilicon film has been deposited by chemical vapor deposition (CVD) on a silicon substrate having a silicon dioxide film and a silicon nitride film by removing irregularities in the polysilicon film, and a step of simultaneously polishing and flattening the silicon dioxide film and silicon nitride film directly beneath and the polysilicon film. The polishing liquid composition of this disclosure is more preferably used in the step of flattening the polysilicon film by removing irregularities, from the viewpoint of achieving both improved polishing speed and improved surface quality.

[0055] The polishing step in the semiconductor substrate manufacturing method of this disclosure can be performed under the same conditions (polishing pressure, polishing liquid composition, and surface temperature of the polishing pad, etc.) as the polishing step in the polishing method of this disclosure described above.

[0056] In one or more embodiments, the semiconductor substrate manufacturing method of the present disclosure may include a dilution step of diluting a concentrate of the polishing solution composition of the present disclosure before the polishing step. For example, water can be used as the diluent.

[0057] In the cleaning step of the semiconductor substrate manufacturing method of this disclosure, inorganic cleaning is preferable from the viewpoint of reducing residue on the silicon substrate surface. Examples of cleaning agents used in inorganic cleaning include an inorganic cleaning agent containing at least one selected from hydrogen peroxide, ammonia, hydrochloric acid, sulfuric acid, hydrofluoric acid, and ozonated water.

[0058] In one or more embodiments, the semiconductor substrate manufacturing method of the present disclosure may further include a step of rinsing the cleaned silicon substrate with water and drying it after the cleaning step.

[0059] In the semiconductor substrate manufacturing method of this disclosure, the polishing step is preferably a finishing polishing step in one or more embodiments, from the viewpoint of achieving both improved polishing speed and storage stability of the concentrate. In the semiconductor substrate manufacturing method of this disclosure, the polishing step is preferably a step preceding the finish polishing step, from the viewpoint of achieving both improved polishing speed and storage stability of the concentrate, and from the viewpoint of improving surface quality, in one or more embodiments. In one or more embodiments, the polishing step preceding the finish polishing step is the finish polishing step 1 in the polishing method of this disclosure described above.

[0060] If the polishing step in the semiconductor substrate manufacturing method of this disclosure is a polishing step in which the above-described finishing polishing step 1 and finishing polishing step 2 are performed in this order, then the finishing polishing steps 1 and 2 can be performed under the same conditions (polishing pressure, polishing liquid composition, and surface temperature of the polishing pad, etc.) as the finishing polishing steps 1 and 2 in the polishing method of this disclosure described above.

[0061] In the semiconductor substrate manufacturing method of this disclosure, if the polishing process is such that the finishing polishing process 1 and the finishing polishing process 2 are performed in the order described above, then after performing the finishing polishing process 1, washing and drying may be performed before performing the finishing polishing process 2. Alternatively, after performing the finishing polishing process 1, the finishing polishing process 2 may be performed without washing and drying. From the viewpoint of improving productivity, it is preferable to perform the finishing polishing process 2 without washing and drying after performing the finishing polishing process 1. [Examples]

[0062] The present disclosure will be further described below with reference to examples, but these are illustrative and the disclosure is not limited to these examples.

[0063] 1. Preparation of polishing solution compositions (Examples 1-3, Comparative Examples 1-2) (Concentrated abrasive composition) A concentrated (20-fold) polishing solution composition was obtained by stirring and mixing silica particles (component A) shown in Table 1, a water-soluble polymer (component B or non-component B) shown in Table 1, and ultrapure water. An appropriate amount of ammonia (component C) was used to adjust the pH. The pH of the concentrated solution was 9.6 to 10.5 at 25°C. (polishing liquid composition) The above concentrate was diluted 20-fold with deionized water to obtain the polishing solution compositions of Examples 1-3 and Comparative Examples 1-2. The content of each component in Table 1 represents the content (mass %) of each component in the diluted polishing solution composition at the time of use. The ultrapure water content is the residue after removing component A and component B or non-component B and component C. The pH of each polishing solution composition (at the time of use) at 25°C was as shown in Table 1.

[0064] The following components A, B, non-component B, and C were used in the preparation of each polishing solution composition. (Component A) Colloidal silica [average primary particle diameter 35 nm, average secondary particle diameter 70 nm, degree of association 2.0] (Component B) PO-modified PEI: PO (propylene oxide)-modified polyethyleneimine [manufactured by Nippon Shokubai Co., Ltd., PP-061, weight-average molecular weight 5,000, ratio of primary and secondary amino groups in the total amino groups of PEI: 0%] (Non-ingredient B) PEI: Polyethyleneimine [Manufactured by Nippon Shokubai Co., Ltd., SP-006, weight-average molecular weight 2,000] HEC: Hydroxyethylcellulose [Daicel Corporation, SE-400, weight-average molecular weight 250,000] (Component C) Ammonia [28% by mass aqueous ammonia, manufactured by Kishida Chemical Co., Ltd., reagent grade]

[0065] 2. Measurement methods for various parameters (1) Measurement of the average primary particle diameter of silica particles (component A) The average primary particle size (nm) of component A is calculated using the specific surface area S (m²) calculated by the BET (nitrogen adsorption) method. 2 The calculation was performed using the following formula with ( / g). Average primary particle diameter (nm)=2727 / S

[0066] The specific surface area S of component A was measured by nitrogen adsorption method (BET method) using a micromeritic automatic specific surface area analyzer (Micromeritic Automatic Specific Surface Area Analyzer "Flowsorb III 2305", manufactured by Shimadzu Corporation) after the following [pretreatment] had been performed. [Pre-processing] (a) Adjust the pH of component A in slurry form to 2.5 ± 0.1 with an aqueous nitric acid solution. (b) Place the slurry-like component A, adjusted to pH 2.5 ± 0.1, into a petri dish and dry it in a hot air dryer at 150°C for 1 hour. (c) After drying, the obtained sample is finely ground in an agate mortar. (d) The pulverized sample is suspended in deionized water at 40°C and filtered through a membrane filter with a pore size of 1 μm. (e) Wash the filtrate on the filter five times with 20g of deionized water (40°C). (f) Place the filter with the filtrate attached into a petri dish and dry it in an atmosphere of 110°C for 4 hours. (g) The dried filtrate (component A) was taken without mixing in any filter debris, and finely ground in a mortar to obtain a measurement sample.

[0067] (2) Average secondary particle diameter of silica particles (component A) The average secondary particle size (nm) of component A was measured by adding silica particles to deionized water so that the concentration of component A was 0.5% by mass. The resulting aqueous dispersion was then placed in a Disposable Sizing Cuvette (10 mm polystyrene cell) to a height of 10 mm from the bottom, and measured using dynamic light scattering (instrument name: "Zetasizer Nano ZS", Sysmex Corporation).

[0068] (3) Measurement of the weight-average molecular weight of water-soluble polymers The weight-average molecular weight of water-soluble polymers was calculated based on the peaks in the chromatogram obtained by applying gel permeation chromatography (GPC) under the following conditions. <Measurement conditions for water-soluble polymers> Equipment: HLC-8320 GPC (manufactured by Tosoh Corporation, with integrated detector) Column: α-M+α-M Eluent: 0.15mol / L Na2SO4,1%CH3COOH / water Flow rate: 1.0mL / min Column temperature: 40℃ Detector: Schodex RI SE-61 differential refractive index detector Standard substance: Monodisperse polyethylene glycol with known molecular weight

[0069] (4) Ratio of primary amino groups to secondary amino groups in the total amino groups of component B The ratio of primary to secondary amino groups in the total amino groups of component B was determined using 13C-NMR. <Measurement conditions> Sample: 200 mg of PO-modified PEI dissolved in 0.6 mL of heavy water. Equipment used: 400MHz 13C-NMR (Agilent Technologies, Inc. "Agilent 400-MR DD2") Measurement conditions: 13C-NMR measurement, pulse interval time 5 seconds, tetramethylsilane used as the standard peak (σ: 0.0 ppm). Total number of times: 5000 Peak ranges used for integration: A: 39.0~42.0 ppm (integral value of the primary amine peak) B: 47.0~52.0 ppm (integral value of the secondary amine peak) C: 53.0~58.0 ppm (integral value of the tertiary amine peak) <Ratio of primary and secondary amino groups in total amino groups> The ratio of primary to secondary amino groups in the total number of amino groups can be calculated using the following formula. The ratio (equivalent ratio) of primary and secondary amino groups in the total number of amino groups = (A + B) / (A + B + C)

[0070] (5) pH of the polishing solution composition The pH at 25°C was measured using a pH meter (Toa Denpa Kogyo Co., Ltd., HM-30G), and the value was obtained 1 minute after immersing the pH meter electrode in the polishing solution composition or its concentrate.

[0071] 3. Evaluation of the polishing liquid compositions of Examples 1-3 and Comparative Examples 1-2 (1) Polishing method etc. For each polishing solution composition, the following silicon substrates were subjected to finish polishing and cleaning under the following polishing conditions. <Polished silicon substrate> Single-crystal silicon substrate [200mm diameter, single-sided mirror-finished silicon substrate, conduction type: P, crystal orientation: 100, resistivity: 0.1Ω·cm or more and less than 100Ω·cm] The above single-crystal silicon substrate was pre-polished using a commercially available polishing solution composition (GLANZOX 1302, manufactured by Fujimi Incorporated). The haze of the single-crystal silicon substrate after rough polishing and before finishing polishing was 2-3 ppm.

[0072] <Finishing polishing conditions> Grinding machine: Single-sided 8-inch grinding machine "GRIND-X SPP600s" (manufactured by Okamoto Kogyo) Polishing pad: Suede pad (manufactured by Toray Cortex, Asker hardness: 64, thickness: 1.37 mm, nap length: 450 μm, opening diameter: 60 μm) Silicon substrate polishing pressure: 100 g / cm² 2 Plate rotation speed: 60 rpm Polishing time: 5 minutes Supply rate of polishing solution composition: 150 g / min Temperature of polishing solution composition: 23℃ Carrier rotation speed: 62 rpm

[0073] <Measurement of surface roughness (haze) of silicon substrate> The values ​​used were those measured using the dark-field wide oblique incidence channel (DWO) haze, obtained with the "Surfscan SP1-DLS" surface roughness measurement device (manufactured by KLA Tencor).

[0074] <Cleaning method> After final polishing, the silicon substrate was subjected to ozone cleaning and dilute hydrofluoric acid cleaning as described below. For ozone cleaning, an aqueous solution containing 20 ppm ozone was sprayed from a nozzle at a flow rate of 1 L / min towards the center of the silicon substrate rotating at 600 rpm for 3 minutes. The temperature of the ozonated water was kept at room temperature. Next, dilute hydrofluoric acid cleaning was performed. For dilute hydrofluoric acid cleaning, an aqueous solution containing 0.5 mass% ammonium hydrogen fluoride (special grade, Nakarai Tex Co., Ltd.) was sprayed from a nozzle at a flow rate of 1 L / min towards the center of the silicon substrate rotating at 600 rpm for 6 seconds. The above ozone cleaning and dilute hydrofluoric acid cleaning were performed as one set, for a total of two sets, and finally, spin drying was performed. For spin drying, the silicon substrate was rotated at 1,500 rpm.

[0075] (2) Evaluation of polishing speed The weight of each silicon substrate before and after polishing was measured using a precision balance (Sartorius BP-210S). The weight difference was divided by the density, area, and polishing time of the silicon substrate to determine the single-sided polishing rate per unit time. The results are shown in Table 1 as relative values ​​with Comparative Example 2 set to 100. Note that the weight of the silicon substrate after polishing refers to the weight of the silicon substrate after the above-mentioned finish polishing and cleaning.

[0076] (3) Evaluation of the storage stability of the concentrate 100g of the concentrate of each polishing solution composition was placed in a 100ml screw-top tube and sealed. The storage stability after one day was evaluated according to the following criteria. The concentrates of the polishing solution compositions were stored in a room at 23°C. The results are shown in Table 1. <Evaluation Criteria> A: The concentrated polishing solution composition maintains its dispersion stability without the occurrence of aggregates or separation after one day has elapsed since preparation. B: Abrasives and separation have occurred slightly one day after the preparation of the concentrated polishing solution composition. C: Abrasives and separation have occurred one day after the preparation of the concentrated polishing solution composition.

[0077] (4) Average particle diameter Da of silica particles (component A) The average particle size Da of component A was measured using dynamic light scattering (instrument name: "Zetasizer Nano ZS", manufactured by Sysmex Corporation) after filling a Disposable Sizing Cuvette (10 mm polystyrene cell) with the polishing liquid composition shown in Table 1 to a height of 10 mm from the bottom.

[0078] [Table 1]

[0079] As shown in Table 1, the polishing liquid compositions of Examples 1 to 3 were found to achieve both improved polishing speed and storage stability of the concentrate compared to the polishing liquid compositions of Comparative Examples 1 and 2.

[0080] 4.2 Evaluation of multi-stage polishing (Example 4, Comparative Example 3) (1) (Multi-stage) Continuous polishing After performing finish polishing step 1, multi-stage polishing was performed by changing the polishing machine (polishing platen) and continuously performing finish polishing step 2 without washing and drying. For finish polishing step 1, the polishing liquid compositions shown in Table 2 (Example 1, Comparative Example 1) were used, and for finish polishing step 2, the polishing liquid composition described below was used. Finish polishing step 2 was performed under the same polishing conditions as the finish polishing described in 3. above. <Polishing liquid composition for finishing polishing step 2> The finishing polishing liquid compositions of Example 4 and Comparative Example 3 were prepared by stirring and mixing the silica particles shown in Table 2, the water-soluble polymers (HEC, PEG) shown in Table 2, and ultrapure water. An appropriate amount of ammonia was used to adjust the pH. The pH of the prepared polishing liquid composition at 25°C was 10.3. This finishing polishing composition was used as is as the polishing liquid in the finishing polishing step 2. The content (mass %) of each component is shown in Table 2. The ultrapure water content is the residue after removing silica particles, water-soluble polymers (HEC, PEG), and ammonia. The following components were used to prepare the polishing solution composition for the final polishing step 2. (Silica particles) Colloidal silica [average primary particle diameter 35 nm, average secondary particle diameter 70 nm, degree of association 2.0] (Water-soluble polymer) HEC: Hydroxyethylcellulose [Daicel Corporation, SE-400, weight-average molecular weight 250,000] PEG: Polyethylene glycol [Manufactured by Wako Pure Chemical Industries, Ltd., Grade 1, weight-average molecular weight 6,000] (ammonia) Ammonia [28% by mass aqueous ammonia, manufactured by Kishida Chemical Co., Ltd., reagent grade]

[0081] (2) Measurement of surface defects (LPDs) in silicon substrates The surface defects (LPDs) of the silicon substrate after the multi-stage polishing and cleaning described above were measured in the same manner as described above. The results are shown in Table 2 as relative values ​​with Comparative Example 3 set to 100.

[0082] [Table 2]

[0083] As shown in Table 2, in Example 4, by using the polishing solution of Example 1 described in Table 1 for finish polishing 1, the number of surface defects (LPD) after finish polishing step 2 was reduced compared to Comparative Example 3. [Industrial applicability]

[0084] The polishing fluid composition of this disclosure can achieve both improved polishing speed and storage stability of the concentrate. Therefore, the polishing fluid composition of this disclosure is useful as a polishing fluid composition used in the manufacturing process of various semiconductor substrates, and in particular is useful as a polishing fluid composition for finishing the polishing of silicon substrates.

Claims

1. A polishing composition for silicon substrates, comprising silica particles (component A), a water-soluble polymer (component B) having an amino group bonded to a hydroxyalkyl group, and water.

2. 2. The polishing composition according to claim 1, wherein Component B is an amino group-containing water-soluble polymer having a structure represented by the following formula (1): 【Chemistry 1】 In formula (1), R represents a hydrogen atom, a methyl group, or a hydroxymethyl group.

3. 2. The polishing composition according to claim 1, wherein Component B has a weight average molecular weight of 200 or more and 200,000 or less.

4. The polishing composition according to claim 1 , wherein the content of Component B is 0.001 mass % or more and 0.1 mass % or less.

5. The polishing composition according to claim 1 , wherein the content of Component A is 0.3 mass % or more.

6. 6. The polishing composition according to claim 1, which is used in a polishing step prior to a finish polishing step in a multi-step polishing of a silicon substrate.

7. A method for polishing a silicon substrate, comprising the step of polishing a silicon substrate to be polished with the polishing composition according to claim 1 .

8. A method for polishing a silicon substrate, comprising a finish polishing step 2 for performing finish polishing of a silicon substrate, and a finish polishing step 1 which is a polishing step prior to the finish polishing step 2, the finish polishing step 1 and the finish polishing step 2 being performed in this order, In the finish polishing step 1, polishing is performed using the polishing composition according to any one of claims 1 to 5, In the final polishing step 2, polishing is performed using a polishing composition containing silica particles and a water-soluble polymer. A method for polishing silicon substrates.

9. A method for manufacturing a semiconductor substrate, comprising carrying out the polishing method according to claim 7.

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