JP6366139B2 - Method for producing polishing composition for silicon wafer - Google Patents

Description

  The present invention relates to a method for producing a polishing composition for a silicon wafer, a method for producing a semiconductor substrate using the polishing composition for a silicon wafer, and a method for polishing a silicon wafer to be polished.

  In recent years, design rules for semiconductor devices have been increasingly miniaturized due to increasing demand for higher recording capacity of semiconductor memories. For this reason, the depth of focus becomes shallower in photolithography performed in the manufacturing process of a semiconductor device, and the demands for defect reduction and smoothness of silicon wafers (bare wafers) are becoming stricter.

  In order to improve the quality of silicon wafers, polishing of silicon wafers is performed in multiple stages. In particular, the final polishing performed in the final stage of polishing is a surface defect (LPD: Light point) such as particles, scratches and pits due to suppression of surface roughness (haze) and improvement of wettability (hydrophilization) of the silicon wafer surface after polishing. This is done to reduce defects).

  As a polishing liquid composition used for polishing silicon wafers, silica particles are contained for the purpose of ensuring a polishing rate that ensures good productivity and reducing surface defects (LPD) and surface roughness (haze). A polishing composition for silicon wafers containing a nitrogen basic compound and a water-soluble polymer compound containing a structural unit derived from an acrylamide derivative such as hydroxyethylacrylamide (HEAA) is disclosed (Patent Document 1).

JP 2013-222863 A

  The polishing composition described in Patent Document 1 has a low surface roughness (haze), a low surface defect (LPD), and a high level even when stored at 25 ° C. for a long period (for example, one month). For example, when stored at 40 ° C. for a long time (1 month), the surface roughness (haze) and surface defects (LPD) of the silicon wafer are reduced and good productivity is ensured. This makes it difficult to achieve both a high polishing rate (hereinafter sometimes abbreviated as “high polishing rate”).

  Therefore, in the present invention, even after a long-term storage at a high temperature (hereinafter sometimes abbreviated as “high-temperature long-term storage”), the surface roughness (haze) and surface defects (LPD) of the silicon wafer are reduced and high. Provided are a method for producing a polishing composition for a silicon wafer, a method for producing a semiconductor substrate using the polishing composition for a silicon wafer, and a method for polishing a silicon wafer to be polished, which are compatible with the polishing rate.

  The method for producing a polishing composition for a silicon wafer of the present invention is for a silicon wafer containing silica particles (component A), a nitrogen-containing basic compound (component B), and a water-soluble polymer compound (component C). A method for producing a polishing liquid composition, wherein the content of the silica particles (component A) is 1% by mass or more and 20% by mass or less, and the content of the nitrogen-containing basic compound (component B) is 0.1% by mass or more. The temperature of the mixed solution in which the content of the water-soluble polymer compound (component C) is 0.1% by mass or more and 10% by mass or less is 30 ° C. or more and 80 ° C. for 1 day or more and 180 days or less. The temperature maintenance process maintained below is included.

  The polishing method for a silicon wafer to be polished according to the present invention includes a polishing step of polishing the silicon wafer to be polished using the polishing composition for silicon wafer manufactured by the method for manufacturing a polishing liquid composition for silicon wafer according to the present invention. .

  The manufacturing method of the semiconductor substrate of this invention includes the grinding | polishing process of grind | polishing a to-be-polished silicon wafer using the polishing liquid composition for silicon wafers manufactured by the manufacturing method of the polishing liquid composition for silicon wafers of this invention.

  According to the present invention, a method for producing a polishing composition for a silicon wafer that can achieve both a reduction in surface roughness (haze) and surface defects (LPD) and a high polishing rate even after high-temperature and long-term storage. And the polishing method of the to-be-polished silicon wafer using the said polishing liquid composition for silicon wafers, and the manufacturing method of a semiconductor substrate can be provided.

ただし、上記一般式(１)において、Ｒ₁、Ｒ₂は、それぞれ独立して、水素、炭素数が１〜８のアルキル基、又は炭素数が１〜２のヒドロキシアルキル基を示し、Ｒ₁、Ｒ₂の両方が水素であることはない。 The present invention relates to a method for producing a polishing composition for a silicon wafer (hereinafter referred to as “this”) containing silica particles (component A), a nitrogen-containing basic compound (component B), and a water-soluble polymer compound (component C). The water-soluble polymer compound (component C) preferably contains a structural unit represented by the following general formula (1).

However, in the general formula (1), R ₁ and R ₂ each independently represent hydrogen, an alkyl group having 1 to 8 carbon atoms, or a hydroxyalkyl group having 1 to 2 carbon atoms, and R ₁ , R ₂ are not both hydrogen.

  In the manufacturing method of the polishing liquid composition of the present invention, the content of the silica particles (component A) is 1% by mass or more and 20% by mass or less, and the content of the nitrogen-containing basic compound (component B) is 0.1% by mass. % To 5% by mass, and the temperature of the liquid mixture in which the content of the water-soluble polymer compound (component C) is 0.1% by mass to 10% by mass is 30 ° C. or more for 1 day to 180 days. By including a temperature maintaining step (also referred to as an “aging step”) that is maintained at 80 ° C. or lower, the surface roughness (haze) and surface defects (LPD) can be reduced and increased even after high-temperature and long-term storage performed thereafter. This is based on the knowledge that both the polishing speed can be achieved. In the temperature maintaining step, the temperature of the mixed solution may vary as long as it is within the temperature range of 30 ° C. or higher and 80 ° C. or lower, but the temperature of the mixed solution is preferably within the range of 30 ° C. or higher and 80 ° C. or lower. The temperature is kept at a certain predetermined temperature, preferably the temperature difference is within 20 ° C., more preferably kept almost constant.

  The details of the mechanism of the effects of the present invention are not clear, but are estimated as follows. The water-soluble polymer compound (component C) in the polishing liquid composition (hereinafter sometimes abbreviated as “polishing liquid composition”) produced by the method for producing a polishing liquid composition for silicon wafers of the present invention, It has a hydrophobic part such as an alkyl group and a hydrophilic part. The hydrophilic part interacts with the silica particles, and the hydrophobic part interacts with the silicon wafer. Therefore, the water-soluble polymer compound (component C) is moderately adsorbed on the silicon wafer surface to suppress corrosion by the nitrogen-containing basic compound, thereby achieving good surface roughness (haze) and good wetting. It is possible to reduce surface defects (LPD) by suppressing adhesion of particles due to drying of the silicon wafer surface. In the water-soluble polymer containing the structural unit represented by the general formula (1), the hydrophilic part that interacts with the silica particles is an amide group, and the site that interacts with the silicon wafer is an alkyl group or hydroxyl group that is a hydrophobic part. It is a group.

  In general, the surface charges of the silica particles and the silicon wafer are both negatively charged under alkaline conditions, and the silica particles cannot approach the silicon wafer due to the charge repulsion, and the polishing rate cannot be fully expressed. However, the presence of the water-soluble polymer compound (component C) in the polishing composition causes the water-soluble polymer compound (component C) to be adsorbed on the surfaces of both the silica particles and the silicon wafer. Function as. As a result, the interaction between the silica particles and the silicon wafer becomes stronger, and the polishing with the silica particles proceeds efficiently, so that the water-soluble polymer compound (component C) contributes to securing a high polishing rate of the silicon wafer. It is thought that there is.

  And before the high temperature long-term preservation | save of polishing liquid composition, the temperature maintenance by which the said liquid mixture is preserve | saved at the temperature of 30 degreeC or more and 80 degrees C or less for 1 day or more and 180 days or less in the manufacture process of polishing liquid composition. If it passes through a process (aging process), the molecular structure of a water-soluble polymer compound (component C) will be in a stable state. As a result, the function of the water-soluble polymer compound (component C) as a binder that adsorbs to both the silica particles and the silicon wafer surface during polishing is suppressed, so that the polishing rate decreases due to high-temperature long-term storage. It is suppressed. That is, it is presumed that the presence state of the water-soluble polymer compound (component C) in the aqueous medium (component D) is constant, and an optimal adsorption state is formed.

  The method for producing a polishing liquid composition of the present invention comprises at least the silica particles (component A), the nitrogen-containing basic compound (component B), and the water-soluble polymer compound (component C) before the temperature maintaining step. ), An aqueous medium, and optional components as necessary, the content of the silica particles (component A) is 1% by mass to 20% by mass, and the nitrogen-containing basic compound (component B) is contained. A step of preparing a mixed solution having an amount of 0.1% by mass to 5% by mass and a content of the water-soluble polymer compound (component C) of 0.1% by mass to 10% by mass.

  The silica particles (component A) can be dispersed in the aqueous medium (component D) using, for example, a stirrer such as a homomixer, a homogenizer, an ultrasonic disperser, a wet ball mill, or a bead mill. When coarse particles generated by aggregation of silica particles or the like are contained in the aqueous medium (component D), it is preferable to remove the coarse particles by centrifugation or filtration using a filter. The dispersion of the silica particles (component A) in the aqueous medium (component D) is preferably performed in the presence of a water-soluble polymer compound (component C).

[Silica particles (component A)]
The mixed solution and the polishing composition contain silica particles as an abrasive. Specific examples of the silica particles include colloidal silica and fumed silica. Colloidal silica is more preferable from the viewpoint of improving the surface smoothness of the silicon wafer.

  The use form of the silica particles is preferably a slurry from the viewpoint of operability. When the abrasive contained in the mixed solution and the polishing composition is colloidal silica, from the viewpoint of preventing contamination of the silicon wafer by alkali metal or alkaline earth metal, colloidal silica is derived from a hydrolyzate of alkoxysilane. It is preferable that it is what was obtained. Silica particles obtained from the hydrolyzate of alkoxysilane can be produced by a conventionally known method.

  From the viewpoint of ensuring a high polishing rate, the average primary particle size of the silica particles contained in the mixed solution and polishing solution composition is preferably 5 nm or more, more preferably 10 nm or more, still more preferably 15 nm or more, and even more. Preferably it is 30 nm or more. Further, from the viewpoint of achieving both reduction in surface roughness and surface defects (LPD) and a high polishing rate, the thickness is preferably 50 nm or less, more preferably 45 nm or less, and further preferably 40 nm or less.

  In particular, when colloidal silica is used as the silica particles, the average primary particle diameter is preferably 5 nm or more, more preferably 10 nm or more, still more preferably 15 nm or more, and still more preferably, in order to ensure a high polishing rate. 30 nm or more. Further, from the viewpoint of achieving both reduction in surface roughness and surface defects (LPD) and a high polishing rate, the thickness is preferably 50 nm or less, more preferably 45 nm or less, and further preferably 40 nm or less.

The average primary particle diameter of the silica particles is calculated using a specific surface area S (m ² / g) calculated by a BET (nitrogen adsorption) method. A specific surface area can be measured by the method as described in an Example, for example.

  The degree of association of the silica particles is preferably 3.0 or less, more preferably 1.1 or more and 3.0 or less, and more preferably 1.8 or more and 2 from the viewpoint of ensuring a high polishing rate and reducing the surface roughness and surface defects. 0.5 or less is more preferable, and 2.0 or more and 2.3 or less is even more preferable. The shape of the silica particles is preferably a so-called spherical type and a so-called mayu type. When the silica particles are colloidal silica, the degree of association is preferably 3.0 or less, more preferably 1.1 or more and 3.0 or less, from the viewpoint of securing a high polishing rate and reducing the surface roughness and surface defects. Preferably, it is 1.8 or more and 2.5 or less, and 2.0 or more and 2.3 or less is still more preferable.

The association degree of silica particles is a coefficient representing the shape of silica particles, and is calculated by the following formula. The average secondary particle diameter is a value measured by a dynamic light scattering method, and can be measured using, for example, the apparatus described in the examples.
Degree of association = average secondary particle size / average primary particle size

  The method for adjusting the degree of association of the silica particles is not particularly limited. For example, JP-A-6-254383, JP-A-11-214338, JP-A-11-60232, JP-A-2005-060217, A method described in JP-A-2005-060219 or the like can be employed.

  The content of the silica particles in the mixed solution is 1% by mass or more, preferably 3% by mass or more, more preferably 5% by mass or more, from the viewpoint of reducing production and transportation costs. From the viewpoint of suppressing aggregation of particles and improving dispersion stability, it is 20% by mass or less, preferably 15% by mass or less, more preferably 12% by mass or less.

[Nitrogen-containing basic compound (component B)]
The mixed liquid and the polishing liquid composition are prepared from a water-soluble basic compound from the viewpoints of improving the storage stability of the polishing liquid composition, ensuring a high polishing rate, and reducing surface roughness and surface defects (LPD). contains. The water-soluble basic compound is at least one nitrogen-containing basic compound selected from amine compounds and ammonium compounds. Here, “water-soluble” means having a solubility of 2 g / 100 ml or more in water (20 ° C.), and “water-soluble basic compound” means basicity when dissolved in water. Refers to the compound shown.

  Examples of at least one nitrogen-containing basic compound selected from amine compounds and ammonium compounds include ammonia, ammonium hydroxide, ammonium carbonate, ammonium hydrogen carbonate, methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, Monoethanolamine, diethanolamine, triethanolamine, N-methylethanolamine, N-methyl-N, N-diethanolamine, N, N-dimethylethanolamine, N, N-diethylethanolamine, N, N-dibutylethanol Amine, N- (β-aminoethyl) ethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, ethylenediamine, hexamethylenedia Down, piperazine hexahydrate, anhydrous piperazine, 1- (2-aminoethyl) piperazine, N- methylpiperazine, diethylenetriamine, tetramethylammonium hydroxide, and include hydroxylamine. The hydroxyamine is preferably a chain hydroxyamine, more preferably a monohydroxymonoamine, and even more preferably 2-aminoethanol. These nitrogen-containing basic compounds may be used as a mixture of two or more. Nitrogen-containing basic compounds that can be contained in the mixed liquid and polishing liquid composition include a reduction in surface roughness and surface defects (LPD), an improvement in storage stability of the polishing liquid composition, and a high polishing rate. In view of the above, ammonia, a mixture of ammonia and hydroxyamine is preferable, and ammonia is more preferable.

  The content of the nitrogen-containing basic compound (component B) in the mixed solution is 0.1% by mass or more, preferably 0.2% by mass or more, from the viewpoint of reducing production and transportation costs. Preferably, it is 0.3% by mass or more, and from the viewpoint of improving storage stability, it is 5% by mass or less, preferably 3% by mass or less, and more preferably 1% by mass or less.

[Water-soluble polymer compound (component C)]
The mixed liquid and the polishing liquid composition are water-soluble polymer compounds (components) from the viewpoint of improving the storage stability of the polishing liquid composition, ensuring a high polishing rate, and reducing the surface roughness and surface defects of the silicon wafer. C). In the present invention, “water-soluble” of the water-soluble polymer compound means having a solubility of 0.5 g / 100 ml or more, preferably 2 g / 100 ml or more in water (20 ° C.).

  As a monomer that is a supply source of the structural unit constituting the water-soluble polymer compound (component C), from the viewpoint of ensuring the polishing rate, and reducing the surface defects (LPD) and surface roughness (haze) of the silicon wafer. Examples thereof include monomers having a water-soluble group such as an amide group, a hydroxyl group, a carboxyl group, a carboxylic acid ester group, and a sulfonic acid group.

Specific examples of the water-soluble polymer compound (component C) include water-soluble polymer compounds containing structural units derived from polyamide, cellulose derivatives, polyvinyl alcohol, and acrylamide derivatives. Examples of the polyamide include polyvinyl pyrrolidone, polyacrylamide, polyoxazoline, polydimethylacrylamide, polydiethylacrylamide, polyisopropylacrylamide, polyhydroxyethylacrylamide and the like. Examples of cellulose derivatives include carboxymethyl cellulose, hydroxyethyl cellulose (HEC), hydroxyethyl methyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, ethyl cellulose, hydroxyethyl ethyl cellulose, and carboxymethyl ethyl cellulose. Examples of the water-soluble polymer compound containing a structural unit derived from an acrylamide derivative include a water-soluble polymer compound containing preferably 75% by mass or more of the structural unit I represented by the following general formula (1).

In the following general formula (1), R ₁ and R ₂ are each independently hydrogen, an alkyl group having 1 to 8 carbon atoms, or a hydroxyalkyl group having 1 to 2 carbon atoms, more preferably hydrogen. An atom, an alkyl group having 1 to 4 carbon atoms, or a hydroxyalkyl group having 1 to 2 carbon atoms, particularly preferably a hydrogen atom, a methyl group, an ethyl group, an isopropyl group, or a hydroxyethyl group. However, those in which both R ₁ and R ₂ are not hydrogen are mentioned. The monomer that is the supply source of the structural unit I represented by the general formula (1) is an acrylamide derivative such as N-hydroxyethylacrylamide (HEAA) or N-hydroxymethylacrylamide (HMAA). These can be used singly or in combination of two or more. Among these monomers, HEAA is preferable from the viewpoint of reducing surface defects (LPD) and surface roughness (haze) of the silicon wafer.

  For a water-soluble polymer compound containing a structural unit derived from an acrylamide derivative, “comprising preferably 75% by mass or more of the structural unit I” means that the mass of the structural unit I in one molecule of the water-soluble polymer compound is It means that the weight average molecular weight (Mw) of the water-soluble polymer compound is preferably 75% or more. Further, in this specification, the content (% by mass) of the structural unit I occupying in all the structural units constituting the water-soluble polymer compound may be reacted in all steps of the synthesis of the water-soluble polymer compound depending on the synthesis conditions. A value calculated from the amount (% by mass) of the compound for introducing the structural unit I charged in the reaction tank in the compound for introducing all the structural units charged in the tank may be used. .

  The proportion of the structural unit I in all the structural units of the water-soluble polymer compound containing a structural unit derived from an acrylamide derivative is preferably from the viewpoint of reducing surface defects (LPD) and surface roughness (haze) of the silicon wafer. Is 75% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, and still more preferably substantially 100% by mass.

  The water-soluble polymer compound containing a structural unit derived from an acrylamide derivative may contain a structural unit other than the structural unit I as long as the effect of the present invention is exhibited. When a structural unit other than the structural unit I (also referred to as “structural unit II”) is included, the structural unit II is N from the viewpoint of reducing surface defects (LPD) and surface roughness (haze) of the silicon wafer. -Configuration derived from at least one monomer selected from the group consisting of isopropylacrylamide (NIPAM), acrylic acid (AA), methacrylic acid (MAA), vinylpyrrolidone (VP), dimethylacrylamide (DMAA) and diethylacrylamide (DEAA) Unit II is preferred, and N-isopropylacrylamide (NIPAM) is more preferred.

The structural unit I represents R ₁ and R ₂ in the general formula (1) from the viewpoints of improving the storage stability of the polishing composition, ensuring a high polishing rate, and reducing the surface roughness and surface defects of the silicon wafer. Are structural units I-I and R _{1 in} which R ₁ is a hydrogen atom and R ₂ is an alkyl group having 1 to 8 carbon atoms, and R ₁ is hydrogen. It is preferable that it is at least one selected from the group consisting of structural units I-III which are atoms and R ₂ is a hydroxyalkyl group having 1 to ₂ carbon atoms. In the structural unit II, from the viewpoint of securing a high polishing rate, both R ₁ and R ₂ are preferably a methyl group or an ethyl group, and more preferably an ethyl group. From the viewpoint of reducing the surface roughness, it is preferable that R ₂ is an isopropyl group in the structural unit I-II. In view of securing a high polishing rate and reducing surface defects, R ₂ in the structural unit I-III is preferably a hydroxyethyl group.

  As a monomer which is a supply source of the structural unit I represented by the general formula (1), N-methylacrylamide, N-ethylacrylamide, N-propylacrylamide, N-isopropylacrylamide (NIPAM), N-butylacrylamide N-isobutylacrylamide, N-tertiarybutylacrylamide, N-heptylacrylamide, N-octylacrylamide, N-tertiaryoctylacrylamide, N-methylolacrylamide, N-hydroxyethylacrylamide (HEAA), N, N-dimethylacrylamide (DMAA), N, N-diethylacrylamide (DEAA), N, N-dipropylacrylamide, N, N-diisopropylacrylamide, N, N-dibutylacrylamide, N, N-diisobutyla Riruamido, N, N-di-heptyl acrylamide, N, N-dioctyl acrylamide, N, N-dimethylol acrylamide, N, N-dihydroxyethyl acrylamide and the like. These can be used alone or in combination of two or more. Among these monomers, N-isopropylacrylamide, N-hydroxyethylacrylamide, N, N-dimethylacrylamide, and N, N-diethylacrylamide are preferable from the viewpoint of reducing the surface roughness and ensuring a high polishing rate. N-hydroxyethylacrylamide and N, N-diethylacrylamide are more preferable, and N-hydroxyethylacrylamide is more preferable from the viewpoint of reducing surface defects.

The proportion of the structural unit I represented by the general formula (1) in all the structural units constituting the water-soluble polymer compound (component C) is such that R ₁ and R ₂ are both hydroxy having 1 to 2 carbon atoms. When the alkyl group is not an alkyl group, it is preferably 10% by mass or more, more preferably 20% by mass or more, and still more preferably 40% by mass or more from the viewpoint of reducing the surface roughness and surface defects of the silicon wafer. From the viewpoint of securing the speed, it is preferably 100% by mass or less, more preferably 90% by mass or less, and still more preferably 60% by mass or less. When _one or both of R ₁ and R ₂ is a hydroxyalkyl group having 1 to 2 carbon atoms, the proportion of the structural unit I in all the structural units of the water-soluble polymer compound (component C) is: From the viewpoint of reducing the surface roughness and surface defects of the silicon wafer, it is preferably 10% by mass or more, more preferably 60% by mass or more, still more preferably 80% by mass or more, and from the viewpoint of ensuring a high polishing rate, Is 100 mass% or less.

The water-soluble polymer compound (component C) is composed of the structural unit II (acrylamide (AAm)) represented by the following general formula (2) from the viewpoint of ensuring a high polishing rate and reducing the surface roughness and surface defects. What has is preferable.

  When the water-soluble polymer compound (component C) is a copolymer containing the structural unit I represented by the general formula (1) and the structural unit II represented by the general formula (2), all structural units The proportion of the structural unit I is preferably 10% by weight or more, more preferably 20% by weight or more, and still more preferably 40% by weight or more, from the viewpoint of reducing the surface roughness and surface defects of the silicon wafer. In view of securing a high polishing rate, it is preferably 100% by mass or less, more preferably 90% by mass or less, and even more preferably 60% by mass or less.

  When the water-soluble polymer compound (component C) is a copolymer containing the structural unit I represented by the general formula (1) and the structural unit II represented by the general formula (2), The proportion of the structural unit II in the structural unit is preferably 20% by mass or more, more preferably 30% by mass or more, and still more preferably 45% by mass or more, from the viewpoint of improving the polishing rate. Therefore, it is preferably 80% by mass or less, more preferably 55% by mass or less.

  The water-soluble polymer compound (component C) may be a copolymer containing a structural unit other than the structural unit I represented by the general formula (1) and the structural unit II represented by the general formula (2). . Examples of the monomer component forming such a structural unit include acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, styrene, vinyl pyrrolidone, and oxazoline.

  In the case where the water-soluble polymer compound (component C) is a copolymer containing the structural unit I represented by the general formula (1) and a structural unit other than the structural unit I, the structural unit I and the structural unit The arrangement in the copolymer of structural units other than I may be block or random.

  The weight average molecular weight of the water-soluble polymer compound (component C) is preferably 50,000 or more, more preferably 100,000 or more, still more preferably 200,000 or more, from the viewpoint of reducing the surface roughness and surface defects of the silicon wafer. More preferably, it is 500,000 or more, and from the viewpoint of securing a high polishing rate, it is preferably 2 million or less, more preferably 1 million or less, still more preferably 900,000 or less, and even more preferably 800,000 or less. In addition, the weight average molecular weight of a water-soluble polymer compound (component C) is measured by the method as described in a later Example.

  The content of the water-soluble polymer compound (component C) in the mixed solution is 0.1% by mass or more, preferably 0.2% by mass or more, more preferably 0.3%, from the viewpoint of reducing production and transportation costs. From the viewpoint of improving storage stability, it is 10% by mass or less, preferably 3% by mass or less, more preferably 1% by mass or less, and still more preferably 0.8% by mass or more. 5% by mass or less.

[Aqueous medium (component D)]
Examples of the aqueous medium (component D) contained in the mixed liquid and the polishing liquid composition include water such as ion-exchanged water and ultrapure water, or a mixed medium of water and a solvent. Solvents that can be mixed with (for example, alcohols such as ethanol) are preferred. Of these, ion-exchanged water or ultrapure water is more preferable, and ultrapure water is more preferable. When component D of the present invention is a mixed medium of water and a solvent, the ratio of water to the entire mixed medium as component D is not particularly limited, but is 95% by mass or more from the viewpoint of economy. Is preferable, 98 mass% or more is more preferable, and 100 mass% is further substantially preferable.

  The content of the aqueous medium in the mixed liquid is not particularly limited, and may be the remainder of Component A to Component C and optional components described later.

  The pH of the mixed solution at 25 ° C. is preferably 8.0 or more, more preferably 9.0 or more, still more preferably 9.5 or more from the viewpoint of ensuring a high polishing rate, and from the viewpoint of safety, Preferably it is 12.0 or less, More preferably, it is 11.5 or less, More preferably, it is 11.0 or less. The pH can be adjusted by appropriately adding a nitrogen-containing basic compound (component B) and / or a pH adjuster described later. Here, the pH at 25 ° C. can be measured using a pH meter (Toa Denpa Kogyo Co., Ltd., HM-30G), and is a value one minute after immersion of the electrode in the polishing composition.

[Optional ingredients]
In the polishing liquid composition obtained by the method for producing the mixed liquid and the polishing liquid composition of the present invention, an alkylene oxide adduct (component E) of a polyhydric alcohol is further added as long as the effects of the present invention are not hindered. At least one optional component selected from water-soluble polymer compounds other than Component C, pH adjusters, preservatives, alcohols, chelating agents, and nonionic surfactants may be included.

<Alkylene oxide adduct of polyhydric alcohol (component E)>
The mixed liquid and the polishing liquid composition may further contain an alkylene oxide adduct of a polyhydric alcohol. Component E is adsorbed on the silicon wafer to be polished. Therefore, the component E is applied to the silicon wafer surface, which is considered to be generated by drying the silicon wafer surface, by imparting wettability to the silicon wafer surface while suppressing corrosion of the silicon wafer surface by the nitrogen-containing basic compound. It acts to suppress the adhesion of particles.

  In addition, in the cleaning process of the polished silicon wafer, the component E weakens the interaction that occurs between the silica particles and the silicon wafer. Therefore, component E, together with the water-soluble polymer compound (component C), is thought to promote the reduction of surface roughness (haze) and surface defects (LPD).

  Component E is a polyhydric alcohol derivative obtained by addition polymerization of a polyhydric alcohol with an alkylene oxide such as ethylene oxide or propylene oxide. Component E contains at least one alkyleneoxy group selected from the group consisting of ethyleneoxy groups and propyleneoxy groups.

  The number of hydroxyl groups of the polyhydric alcohol that is the source (raw material) of component E is the viewpoint of increasing the adsorption strength of component E on the silicon wafer surface, and the viewpoint of reducing the surface defects (LPD) and surface roughness (haze) of the silicon wafer. From the viewpoint of securing a high polishing rate, it is preferably 10 or less, more preferably 8 or less, still more preferably 6 or less, and even more preferably 4 or less.

  Specific examples of Component E include alkylene glycol alkylene oxide adducts such as polyethylene glycol (PEG) and polypropylene glycol, glycerin alkylene oxide adducts, pentaerythritol alkylene oxide adducts, etc. Among these, ethylene glycol Alkylene oxide adducts are preferred.

  Component E contains at least one alkyleneoxy group selected from the group consisting of ethyleneoxy groups (EO) and propyleneoxy groups (PO), but has a surface defect (LPD) and surface roughness (haze) of the silicon wafer. From the viewpoint of reduction, the alkyleneoxy group contained in Component E is preferably composed of at least one alkyleneoxy group selected from the group consisting of EO and PO, and more preferably composed of EO. When the component E contains both EO and PO, the arrangement of EO and PO may be block or random.

  The weight average molecular weight of the component E is preferably 500 or more, more preferably 700 or more, and more preferably 900 or more from the viewpoint of increasing the amount of adsorption of the component E to the polished silicon wafer and reducing the surface roughness (haze). More preferably, from the viewpoint of increasing the amount of component E adsorbed to the polished silicon wafer and reducing the surface roughness (haze), it is preferably 250,000 or less, more preferably 100,000 or less, and even more preferably 20,000 or less. Even more preferably 10,000 or less.

The weight average molecular weight of component E can be calculated based on a peak in a chromatogram obtained by applying a gel permeation chromatography (GPC) method under the following conditions.
<Measurement condition>
Equipment: HLC-8320 GPC (Tosoh Corporation, detector integrated type)
Column: GMPWXL + GMPWXL (anion)
Eluent: 0.2M phosphate buffer / CH ₃ CN = 9/1
Flow rate: 0.5ml / min
Column temperature: 40 ° C
Detector: RI Detector Reference material: Monodispersed polyethylene glycol with known molecular weight

  The content of Component E contained in the liquid mixture is preferably 0.0001% by mass or more and 0.5% by mass or less, more preferably 0, from the viewpoint of reducing surface roughness (haze) and surface defects (LPD). 0.001% by mass or more and 0.05% by mass or less.

<Preservative>
Preservatives include benzalkonium chloride, benzethonium chloride, 1,2-benzisothiazolin-3-one, (5-chloro-) 2-methyl-4-isothiazolin-3-one, hydrogen peroxide, or hypochlorite Examples include acid salts.

<Alcohols>
Examples of alcohols include methanol, ethanol, propanol, butanol, isopropyl alcohol, 2-methyl-2-propanol, ethylene glycol, propylene glycol, polyethylene glycol, and glycerin. The content of alcohol is preferably 0.1 to 5% by mass in a diluted solution obtained by diluting the concentrated liquid of the polishing composition.

<Chelating agent>
Chelating agents include: ethylenediaminetetraacetic acid, sodium ethylenediaminetetraacetate, nitrilotriacetic acid, sodium nitrilotriacetate, ammonium nitrilotriacetate, hydroxyethylethylenediaminetriacetic acid, sodium hydroxyethylethylenediaminetriacetate, triethylenetetraminehexaacetic acid, triethylenetetramine Examples include sodium hexaacetate. The content of the chelating agent is preferably 0.01 to 1% by mass in a diluted liquid obtained by diluting the concentrated liquid of the polishing liquid composition.

<Nonionic surfactant>
Nonionic surfactants include polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbit fatty acid ester, polyoxyethylene glycerin fatty acid ester, polyoxyethylene fatty acid ester, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl phenyl ether, Examples include polyethylene glycol types such as oxyalkylene (cured) castor oil, polyhydric alcohol types such as sucrose fatty acid ester, polyglycerin alkyl ether, polyglycerin fatty acid ester, alkylglycoside, and fatty acid alkanolamide.

  For example, in the temperature maintaining step (the aging step), the mixed solution is stored in a state where the container is filled so that air and light do not enter as much as possible from the viewpoint of reducing the surface roughness (haze). It is preferable. In addition, the storage of the mixed solution that is the target of the temperature maintaining step and filled in the container is preferably performed in a temperature-controlled room, and the storage temperature of the mixed solution in the temperature maintaining step is the surface roughness (haze) and the surface From the viewpoint of achieving both a reduction in defects (LPD) and a high polishing rate, it is 30 ° C. or higher, preferably 35 ° C. or higher, 80 ° C. or lower, preferably 70 ° C. or lower, more preferably 60 ° C. or lower, even more preferably. It is 45 degrees C or less.

  In the temperature maintaining step, the time for maintaining the mixed solution at a temperature of 30 ° C. or more and 80 ° C. or less is 1 day or more, preferably 10 days or more, more preferably 20 days or more, and further preferably from the viewpoint of improving the polishing rate. Is 40 days or longer, and from the viewpoint of reducing surface defects (LPD) of silicon wafers and improving wettability, it is 180 days or shorter, preferably 120 days or shorter, more preferably 100 days or shorter.

  The polishing liquid composition obtained by the method for manufacturing a polishing liquid composition of the present invention includes, for example, a polishing step for polishing a silicon wafer to be polished and a polishing step for polishing a silicon wafer to be polished in a method for manufacturing a semiconductor substrate. Used for polishing a silicon wafer to be polished.

  About the polishing liquid composition obtained by the manufacturing method of the polishing liquid composition of this invention, when the liquid mixture containing at least component A-component D passes through a temperature maintenance process in the manufacturing process, it is 15 degreeC or more and 55 degreeC, for example. In the following, hydrolysis of the water-soluble polymer compound (component C) that can occur by long-term storage (for example, 15 days or more and 120 days or less) is suppressed. Therefore, if the polishing composition is used in the polishing step, variations in the quality (particularly polishing rate) of the polishing composition that can occur due to differences in transportation environment and storage environment can be effectively reduced.

  The polishing process for polishing the silicon wafer to be polished includes a lapping (rough polishing) process for planarizing a silicon wafer obtained by slicing a silicon single crystal ingot into a thin disk shape, and a lapped silicon wafer. After the etching, it is included in a finish polishing step of mirror-finishing the silicon wafer surface. The polishing composition of the present invention is more preferably used in the above-described finish polishing step.

  The semiconductor substrate manufacturing method of the present invention (hereinafter sometimes abbreviated as “the manufacturing method of the present invention”) and the silicon wafer polishing method of the present invention (hereinafter abbreviated as “the polishing method of the present invention”). In some cases, a polishing liquid composition (concentrated liquid) obtained by storing the mixed liquid at a predetermined temperature at a predetermined temperature for a predetermined period before the polishing process for polishing the silicon wafer to be polished. A dilution step for dilution may be included. That is, in the production method of the present invention and the polishing method of the present invention, the polishing composition may be diluted with an aqueous medium and then used for polishing a silicon wafer to be polished. An aqueous medium may be used as the diluent. In this case, the dilution factor is not particularly limited as long as the concentration at the time of polishing after dilution can be ensured, but it is preferably at least 2 times, more preferably at least 5 times, from the viewpoint of further reducing production and transportation costs. More preferably, it is 10 times or more, still more preferably 20 times or more, and from the viewpoint of improving storage stability, it is preferably 100 times or less, more preferably 90 times or less, still more preferably 80 times or less, still more preferably. 60 times or less.

  In the production method of the present invention and the polishing method of the present invention, when the polishing composition for silicon wafer obtained by diluting the polishing composition (concentrated solution) with an aqueous medium in the dilution step contains coarse particles or the like. It is preferable to remove the coarse particles by filtering the silicon wafer polishing composition using a centrifugal separator or a filter. That is, in the production method of the present invention and the polishing method of the present invention, the polishing liquid composition is preferably diluted 2 to 100 times with an aqueous medium, then filtered and used for polishing a silicon wafer to be polished. May be.

  The content of silica particles (component A) in the polishing composition for silicon wafer diluted with an aqueous medium is preferably 0.05% by mass or more, and 0.1% by mass or more from the viewpoint of securing a high polishing rate. Is more preferable, and 0.2 mass% or more is still more preferable. Further, from the viewpoints of economy and suppression of aggregation of silica particles in the polishing composition and improvement of dispersion stability, it is preferably 10% by mass or less, more preferably 7.5% by mass or less, still more preferably 5% by mass or less. The mass% or less is still more preferable, and 0.5 mass% or less is still more preferable.

  The content of the nitrogen-containing basic compound (component B) in the polishing composition for silicon wafers diluted with an aqueous medium reduces the surface roughness and surface defects of the silicon wafer, and the storage stability of the polishing composition. From the viewpoint of improving and ensuring a high polishing rate, 0.001% by mass or more is preferable, 0.005% by mass or more is more preferable, 0.007% by mass or more is further preferable, and 0.010% by mass or more is even more. preferable. Further, from the viewpoint of reducing the surface roughness and surface defects of the silicon wafer, it is preferably 1% by mass or less, more preferably 0.5% by mass or less, still more preferably 0.1% by mass or less, and 0.05% by mass or less. Is still more preferable, 0.025 mass% or less is further more preferable, 0.018 mass% or less is still more preferable, and 0.014 mass% or less is still more preferable.

  The content of the water-soluble polymer compound (component C) in the polishing composition for silicon wafer diluted with an aqueous medium is preferably 0.002% by mass or more from the viewpoint of reducing the surface roughness of the silicon wafer. More preferably 0.003% by mass or more, still more preferably 0.005% by mass or more, still more preferably 0.008% by mass or more, and preferably 0 from the viewpoint of improving the storage stability of the polishing composition. 0.050% by mass or less, more preferably 0.03% by mass or less, further preferably 0.02% by mass or less, and still more preferably 0.012% by mass or less.

  The content of the polyhydric alcohol alkylene oxide adduct (component E) in the silicon wafer polishing liquid composition diluted with an aqueous medium is from the viewpoint of reducing surface roughness (haze) and surface defects (LPD). Preferably it is 0.00001 mass% or more, More preferably, it is 0.0001 mass% or more, Preferably it is 0.005 mass% or less, More preferably, it is 0.001 mass% or less.

  In the step of polishing the silicon wafer to be polished, for example, the silicon wafer to be polished is sandwiched between a surface plate to which a polishing pad is attached and the silicon wafer to be polished is polished at a polishing pressure of 3 to 20 kPa.

  The polishing pressure refers to the pressure of the surface plate applied to the surface to be polished of the silicon wafer to be polished at the time of polishing. The polishing pressure is preferably 3 kPa or more, more preferably 4 kPa or more, still more preferably 5 kPa or more, and even more preferably 5.5 kPa or more from the viewpoint of improving the polishing rate and economically polishing. Further, from the viewpoint of improving the surface quality and relaxing the residual stress in the polished silicon wafer, the polishing pressure is preferably 20 kPa or less, more preferably 18 kPa or less, and even more preferably 16 kPa or less.

  The production method of the present invention and the polishing method of the present invention further include a step of cleaning the polished silicon wafer after the step of polishing the silicon wafer to be polished using the polishing composition (diluent). .

  The details of the water-soluble polymer compounds in Table 1 used for the preparation of the polishing liquid compositions of Examples 1 and 2 and Comparative Examples 1 to 3 below are as follows.

<Synthesis of water-soluble polymer compound>
[HEAA homopolymer, weight average molecular weight 720,000]
Hydroxyethyl acrylamide 150 g (1.30 mol manufactured by Kojin Co., Ltd.) was dissolved in 100 g of ion exchange water to prepare an aqueous monomer solution. Separately, 0.035 g of 2,2'-azobis (2-methylpropionamidine) dihydrochloride (polymerization initiator, V-50 1.30 mmol, manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved in 70 g of ion-exchanged water, and the polymerization initiator was dissolved. An aqueous solution was prepared. After putting 1180 g of ion-exchanged water into a 2 L separable flask equipped with a Dimroth condenser, thermometer, and crescent Teflon (registered trademark) stirring blade, the inside of the separable flask was purged with nitrogen. Next, after the temperature in the separable flask was raised to 68 ° C. using an oil bath, a monomer aqueous solution and a polymerization initiator aqueous solution prepared in advance were added dropwise over 3.5 hours to perform polymerization. After completion of the dropping, the temperature and stirring were maintained for 4 hours to obtain 1500 g of a colorless and transparent 10% by mass polyhydroxyethylacrylamide aqueous solution.

<Measurement of weight average molecular weight>
(1) Polymerization average molecular weight of water-soluble polymer compound The weight average molecular weight of the water-soluble polymer compound is based on the peak in the chromatogram obtained by applying the gel permeation chromatography (GPC) method under the following conditions. Calculated.
Equipment: HLC-8320 GPC (Tosoh Corporation, detector integrated type)
Column: TSKgel α-M + TSKgel α-M (cation, manufactured by Tosoh Corporation)
Eluent: LiBr (50 mmol / L (0.43 wt%)) and CH3COOH (166.7 mmol / L (1.0 wt%)) are added to ethanol / water (= 3/7) Flow rate: 0.6 mL / min
Column temperature: 40 ° C
Detector: RI Detector Reference material: Monodispersed polyethylene glycol with known molecular weight

<Average primary particle diameter of abrasive (silica particles)>
The average primary particle diameter (nm) of the abrasive was calculated by the following formula using the specific surface area S (m ² / g) calculated by the BET (nitrogen adsorption) method.
Average primary particle diameter (nm) = 2727 / S

  The specific surface area of the abrasive is subjected to the following [pretreatment], and then approximately 0.1 g of a measurement sample is accurately weighed to 4 digits after the decimal point in a measurement cell, and immediately under the measurement at a specific temperature of 110 ° C. for 30 minutes. After drying, the surface area was measured by a nitrogen adsorption method (BET method) using a specific surface area measuring device (Micromeritic automatic specific surface area measuring device Flowsorb III 2305, manufactured by Shimadzu Corporation).

[Preprocessing]
(A) The slurry-like abrasive is adjusted to pH 2.5 ± 0.1 with an aqueous nitric acid solution.
(B) A slurry-like abrasive adjusted to pH 2.5 ± 0.1 is placed in a petri dish and dried 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 ion exchange water at 40 ° C. and filtered through a membrane filter having a pore size of 1 μm.
(E) The filtrate on the filter is washed 5 times with 20 g of ion exchange water (40 ° C.).
(F) The filter with the filtrate attached is taken in a petri dish and dried in an atmosphere of 110 ° C. for 4 hours.
(G) The dried filtrate (abrasive grains) was taken so as not to be mixed with filter waste, and finely pulverized with a mortar to obtain a measurement sample.

<Average secondary particle diameter of abrasive (silica particles)>
The average secondary particle diameter (nm) of the abrasive is such that the abrasive is added to ion-exchanged water so that the concentration of the abrasive is 0.25% by mass, and then the obtained aqueous solution is disposable sizing cuvette (polystyrene 10 mm). The cell was measured up to a height of 10 mm from the bottom and measured using a dynamic light scattering method (device name: Zetasizer Nano ZS, manufactured by Sysmex Corporation).

<Production of liquid mixture>
Silica particles (colloidal silica, average primary particle size 35 nm, average secondary particle size 70 nm, association degree 2), water-soluble polymer compound, polyethylene glycol (EO average added mole number = 25, Mw1000 (catalog value), Wako Pure Chemical Industries, Ltd. Co.), 28 mass% ammonia water (Kishida Chemical Co., Ltd. reagent special grade), and ultrapure water were mixed with stirring to obtain a mixed solution (pH 10.6 ± 0.1 (25 ° C.)). The concentration of each component in the mixed solution is 10% by mass of silica particles, 0.4% by mass of ammonia, 0.4% by mass of the water-soluble polymer compound, and 0.008% by mass of polyethylene glycol. The liquid mixture was subjected to a temperature maintenance process in which the liquid mixture was stored under the management conditions (temperature of liquid mixture, period) described in Table 1. In the temperature maintaining step, the mixture was filled in the container so that air and light did not enter as much as possible.

<Polishing method>
The polishing liquid composition (concentrated liquid) obtained through the temperature maintaining process is stored at 40 ° C. for one month, and then diluted 40 times with ion-exchanged water to give a test liquid (pH 10.6 ± 0.1 (25 ° C.)). This was filtered with a filter (compact cartridge filter MCP-LX-C10S Advantech Co., Ltd.) immediately before polishing, and then a silicon wafer (silicon single-sided mirror wafer with a diameter of 200 mm (conductivity type: P, crystal) under the following polishing conditions Azimuth: 100, resistivity 0.1 Ω · cm or more and less than 100 Ω · cm)). Prior to the final polishing, rough polishing was performed on the silicon wafer in advance using a commercially available polishing composition. The surface roughness (haze) of the silicon wafer subjected to the final polishing after finishing the rough polishing was 2.680 (ppm). This surface roughness (haze) is a value in a dark field wide oblique incidence channel (DWO) measured using Surfscan SP1-DLS (trade name) manufactured by KLA Tencor.

<Finishing polishing conditions>
Polishing machine: Single-sided 8-inch polishing machine GRIND-X SPP600s (manufactured by Okamoto)
Polishing pad: Suede pad (Toray Cortex, Asker hardness 64, thickness 1.37mm, nap length 450um, opening diameter 60um)
Silicon wafer polishing pressure: 100 g / cm ²
Surface plate rotation speed: 60 rpm
Polishing time: 5 minutes Supply rate of polishing liquid composition: 150 g / cm ²
Polishing liquid composition temperature: 23 ° C.
Carrier rotation speed: 60rpm

  After finish polishing, the silicon wafer was subjected to ozone cleaning and dilute hydrofluoric acid cleaning as follows. In ozone cleaning, an aqueous solution containing 20 ppm ozone was sprayed from a nozzle toward the center of a silicon wafer rotating at 600 rpm at a flow rate of 1 L / min for 3 minutes. At this time, the temperature of the ozone water was normal temperature. Next, dilute hydrofluoric acid cleaning was performed. In dilute hydrofluoric acid cleaning, an aqueous solution containing 0.5% by mass of ammonium hydrogen fluoride (special grade: Nacalai Tex Co., Ltd.) was sprayed from a nozzle toward the center of a silicon wafer rotating at 600 rpm at a flow rate of 1 L / min for 6 seconds. The above ozone cleaning and dilute hydrofluoric acid cleaning were performed as a set, for a total of 2 sets, and finally spin drying was performed. In the spin drying, the silicon wafer was rotated at 1500 rpm.

<Evaluation of surface roughness (haze) and surface defect (LPD) of silicon wafer>
For the evaluation of the surface roughness (haze) (ppm) of the cleaned silicon wafer surface, the dark field wide oblique incident channel (DWO) measured using Surfscan SP1-DLS (trade name) manufactured by KLA Tencor. The value at was used. Further, surface defects (LPD) (pieces) were measured at the same time as the Haze measurement, and evaluated by measuring the number of particles having a particle diameter of 45 nm or more on the surface of the silicon wafer. A smaller Haze value indicates higher surface flatness. Moreover, it shows that there are few surface defects, so that the numerical value (particle number) of LPD is small. Table 1 shows the results of surface roughness (haze) and surface defects (LPD). The surface roughness (haze) and surface defect (LPD) were measured on two silicon wafers, and the average values are shown in Table 1.

<Polishing rate ratio before and after storage at 40 ° C. for one month (%)>
The concentrate of the polishing composition obtained through the temperature maintenance step was stored at 40 ° C. for 1 month. The polishing rate was determined for the polishing composition obtained by diluting the concentrated solution of the polishing composition before and after storage at 40 ° C. for one month 40 times, and the polishing rate ratio (%) before and after storage was calculated from the following formula. The polishing rate was measured according to the following <Evaluation of polishing rate>.
Polishing rate ratio (%) = (polishing rate when using the polishing liquid composition after storage / polishing speed when using the polishing liquid composition before storage) × 100

<Evaluation of polishing rate>
The polishing rate was evaluated by the following method. The weight of each silicon wafer before and after polishing was measured using a precision balance ("BP-210S" manufactured by Sartorius), and the obtained weight difference was divided by the density, area and polishing time of the silicon wafer, and unit time The single-side polishing rate per hit was determined.

<Evaluation of wettability>
The area of the hydrophilized part (wet part) on the mirror surface of the silicon wafer (diameter 200 mm) immediately after the finish polishing was visually observed, the wettability was evaluated according to the following evaluation criteria, and the results are shown in Table 1.
(Evaluation criteria)
○: Ratio of wet part area is 60% or more Δ: Ratio of wet part area is 40% or more and less than 60% ×: Ratio of wet part area is less than 40%

  As shown in Table 1, the polishing liquids of Examples 1 and 2 obtained through a temperature maintaining step for maintaining the temperature of the mixed liquid at a temperature in the range of 30 ° C. to 80 ° C. for 1 day or more and 180 days or less. Compared with the polishing liquid compositions of Comparative Examples 1 to 3, the composition can satisfactorily achieve both a reduction in surface roughness (haze) and surface defects (LPD) and a high polishing rate even after high-temperature and long-term storage.

  By using the polishing composition produced by the method for producing the polishing composition of the present invention, the surface roughness (haze) and surface defects (LPD) of the silicon wafer can be reduced and high polishing even after high-temperature and long-term storage. You can balance speed. Therefore, the polishing liquid composition obtained by the manufacturing method of the present invention is useful as a polishing liquid composition used in the manufacturing process of various semiconductor substrates, and in particular, a polishing liquid composition for finish polishing of a silicon wafer. Useful as.

Claims (8)

A method for producing a polishing composition for silicon wafers comprising silica particles (component A), a nitrogen-containing basic compound (component B), and a water-soluble polymer compound (component C);
The content of the silica particles (component A) is 1% by mass to 20% by mass, the content of the nitrogen-containing basic compound (component B) is 0.1% by mass to 5% by mass, and the water-soluble polymer. Including a temperature maintaining step of maintaining the temperature of the mixed liquid having a compound (component C) content of 0.1% by mass or more and 10% by mass or less at 35 ° C. or more and 80 ° C. or less for 10 days or more and 180 days or less. Manufacturing method of polishing liquid composition for wafers. The manufacturing method of the polishing liquid composition for silicon wafers of Claim 1 in which the said water-soluble polymer compound (component C) contains the structural unit represented by General formula (1).

However, in the general formula (1), R ₁ and R ₂ each independently represent hydrogen, an alkyl group having 1 to 8 carbon atoms, or a hydroxyalkyl group having 1 to 2 carbon atoms, and R ₁ , R ₂ are not both hydrogen.   A method for polishing a silicon wafer to be polished, comprising a step of polishing the silicon wafer to be polished using the polishing composition for a silicon wafer manufactured by the method for manufacturing a polishing liquid composition for a silicon wafer according to claim 1 or 2. .   The method for polishing a silicon wafer to be polished according to claim 3, wherein the polishing composition for silicon wafer is diluted with an aqueous medium and then used for polishing the silicon wafer to be polished.   5. The silicon wafer to be polished according to claim 4, wherein the silicon wafer polishing liquid composition is diluted to 2 to 100 times with an aqueous medium and then used for polishing the silicon wafer to be polished after filtration. Polishing method.   A method for manufacturing a semiconductor substrate, comprising a step of polishing a silicon wafer to be polished using the polishing composition for a silicon wafer manufactured by the method for manufacturing a polishing composition for a silicon wafer according to claim 1.   The method for manufacturing a semiconductor substrate according to claim 6, wherein the polishing composition for a silicon wafer is diluted with an aqueous medium and then used for polishing the silicon wafer to be polished.   The manufacturing method of a semiconductor substrate according to claim 7, wherein the polishing composition for silicon wafer is diluted by 2 to 100 times with an aqueous medium and then used for polishing the polished silicon wafer after filtration. Method.