JP6039419B2 - Polishing liquid composition for silicon wafer - Google Patents

Description

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

  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 is reduced in photolithography performed in the manufacturing process of semiconductor devices, and there is a demand for reduction of surface defects (LPD: Light point defects) and surface roughness (Haze) of silicon wafers (bare wafers). It is getting 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 at the final stage of polishing is surface defects (LPD) such as particles, scratches, pits, etc. due to reduction of surface roughness (haze) and improvement of wettability (hydrophilization) of the silicon wafer surface after polishing. It is done for the purpose of reducing.

  The following Patent Documents 1 to 6 disclose polishing liquid compositions used for polishing silicon wafers.

  Patent Documents 1 and 2 describe polishing of a silicon wafer containing colloidal silica, water, and a water-soluble polymer compound (for example, hydroxyethyl cellulose (HEC)) for the purpose of reducing surface roughness (haze). A composition for use is disclosed.

  Patent Document 3 discloses a polishing composition for a silicon wafer containing colloidal silica, water, and a block type polyether having a specific structure.

  Patent Document 4 discloses colloidal silica, water, a water-soluble polymer compound (for example, polyvinyl alcohol (PVA)), and a specific cyclic organic compound (for example, a molecular weight of 80 or more) that contributes to a reduction in surface roughness (haze). A polishing composition for silicon wafers comprising less than 500 crown ethers) is disclosed.

  Patent Document 5 discloses a polishing composition for a silicon wafer containing at least one water-soluble polymer compound selected from the group consisting of colloidal silica, water, HEC and PVA, and a block type polyether having a specific structure. ing.

  Patent Document 6 discloses a polishing composition for a silicon wafer containing colloidal silica, water, a water-soluble polymer compound (water-soluble polysaccharide such as HEC), and a diamine compound to which a block-type polyether is bound. .

JP 2004-128070 A JP 2011-181765 A Japanese Patent Laid-Open No. 2001-110760 JP 2011-119405 A Japanese Patent Laid-Open No. 2005-85858 JP 2011-97050 A

  However, since the polishing liquid composition using HEC is made from cellulose, which is a natural product of HEC, water-insoluble matter derived from cellulose is included, and the water-insoluble matter serves as a nucleus to aggregate silica particles. The storage stability of the polishing liquid composition may be reduced. The presence of silica particle aggregates and the water-insoluble matter itself may cause an increase in surface defects (LPD).

  Although the polishing composition described in Patent Document 4 has a problem of reducing surface roughness (haze), it is insufficient to achieve both surface roughness (haze) reduction and surface defect (LPD) reduction. It is.

  Therefore, in the present invention, a polishing composition for silicon wafers that is excellent in storage stability and can reduce surface defects (LPD) and surface roughness (haze) of silicon wafers, and the polishing composition for silicon wafers. A method for manufacturing a semiconductor substrate using silicon and a method for polishing a silicon wafer are provided.

ただし、前記一般式（１）において、Ｒ¹は炭素数１〜２のヒドロキシアルキル基である。 The polishing composition for silicon wafers of the present invention,
Silica particles;
A nitrogen-containing basic compound;
A water-soluble polymer compound containing 75% by mass or more of a structural unit represented by the following general formula (1) and having a weight average molecular weight of 150,000 to 1,500,000,
A polyhydric alcohol alkylene oxide adduct having a weight average molecular weight of 500 to 250,000,
An aqueous medium,
The polyhydric alcohol alkylene oxide adduct contains at least one alkylene oxide group selected from the group consisting of an ethyleneoxy group and a propyleneoxy group.

However, in the general formula (1), R ¹ is a hydroxyalkyl group having 1 to 2 carbon atoms.

  The method for producing a semiconductor substrate of the present invention includes a step of polishing a silicon wafer using the polishing composition for a silicon wafer of the present invention, and a step of cleaning the polished silicon wafer.

  The polishing method for a silicon wafer of the present invention includes a polishing step of polishing the silicon wafer using the polishing composition for a silicon wafer of the present invention.

  ADVANTAGE OF THE INVENTION According to this invention, it is excellent in storage stability and can reduce the surface defect (LPD) and surface roughness (haze: Haze) of a silicon wafer, The polishing liquid composition for silicon wafers, and the said polishing liquid composition for silicon wafers The manufacturing method of the semiconductor substrate using this, and the grinding | polishing method of a silicon wafer can be provided.

  The present invention includes a water-soluble polymer compound containing 75% by mass or more of the structural unit represented by the general formula (1), having a weight average molecular weight of 150,000 to 1,500,000 and a weight average molecular weight of 500 to 250,000. The polyhydric alcohol alkylene oxide adduct is contained in a polishing liquid composition for silicon wafers (hereinafter sometimes abbreviated as “polishing liquid composition”), and the polyhydric alcohol alkylene oxide adduct is ethylene. When at least one alkylene oxide group selected from the group consisting of an oxy group and a propyleneoxy group is contained, the storage stability of the polishing composition is improved, and the surface of the silicon wafer polished with the polishing composition ( This is based on the knowledge that both surface defects (LPD) and surface roughness (haze) on the polished surface can be reduced.

  The mechanism of manifestation of the effect of the present invention, which is high in storage stability and has a high effect of reducing the surface roughness (haze) and surface defects (LPD) of an object to be polished using the polishing composition. The details of are not clear, but the applicant presumes as follows.

  In the present invention, the water-soluble polymer compound having a weight average molecular weight of 150,000 or more and 1.5 million or less contains 75% by mass or more of the structural unit represented by the general formula (1), and the structural unit contains the silica particles and the silica particles. It includes both an amide group that is a site that acts and a hydroxyl group that is a site that interacts with a silicon wafer. Therefore, water-soluble polymer compounds are moderately adsorbed on the silicon wafer surface to suppress corrosion of the wafer surface by the nitrogen-containing basic compound, and exhibit good wettability, which is considered to be caused by drying of the wafer surface. Suppresses adhesion of particles to the surface. Moreover, since the polishing liquid composition of the present invention does not contain a water-insoluble material derived from the raw material, aggregation of silica particles with the water-insoluble material as a core does not occur, and the storage stability is high. Furthermore, in the present invention, the polyhydric alcohol alkylene oxide adduct is adsorbed on the silica particle surface and the silicon wafer surface with appropriate strength. Therefore, the polyhydric alcohol alkylene oxide adduct is further adsorbed on the surface of the silica particles to improve the dispersibility of the silica particles. In addition, the effect of the water-soluble polymer compound can be complemented by adsorbing the polyhydric alcohol alkylene oxide adduct on the wafer surface.

  As described above, in the present invention, the coexistence of the water-soluble polymer compound and the polyhydric alcohol alkylene oxide adduct improves the storage stability of the polishing composition, and improves the surface defects (LPD) and surface roughness of the silicon wafer ( It is estimated that the reduction of haze has been realized. However, the present invention is not limited to these estimations.

[Water-soluble polymer compound (component A)]
The polishing composition of the present invention contains 75% by mass or more of the structural unit I represented by the following general formula (1) and has a weight average molecular weight of 150,000 from the viewpoint of reducing surface defects and surface roughness of the silicon wafer. More than 1.5 million water-soluble polymer compound (component A) is contained. In the present invention, “water-soluble” of a water-soluble polymer compound means having a solubility of 2 g / 100 ml or more in water. Further, “contains 75% by mass or more of the structural unit represented by the following general formula (1)” means that the mass of the structural unit I in one molecule of the water-soluble polymer compound is the weight average of the water-soluble polymer compound. It means 75% or more of the molecular weight (Mw). In the following general formula (1), R ¹ is a hydroxyalkyl group having 1 to 2 carbon atoms. From the viewpoint of reducing surface defects and surface roughness of the silicon wafer, in the general formula (1), R ¹ is preferably a hydroxyethyl group.

  The monomer that is the supply source of the structural unit I represented by the general formula (1) is N-hydroxyethylacrylamide (HEAA) or N-hydroxymethylacrylamide (HMAA). Or it can be used in combination of two or more. Among these monomers, HEAA is preferable from the viewpoint of surface defects.

  The proportion of the structural unit I in all the structural units of the water-soluble polymer compound (component A) is 75% by mass or more and 80% by mass or more from the viewpoint of reducing surface defects and surface roughness of the silicon wafer. Preferably, 90 mass% or more is more preferable, substantially 100 mass% is further more preferable, and 100 mass% is still more preferable.

The water-soluble polymer compound (component A) may contain a structural unit other than the structural unit I as long as the effects of the present invention are exhibited. The structural unit other than the structural unit I (also referred to as the structural unit II) may be a compound that can be copolymerized with the structural unit I. From the viewpoint of reducing surface defects on the silicon wafer surface, N-isopropylacrylamide (NIPAM) A structural unit II derived from at least one monomer selected from the group consisting of methacrylic acid (MAA), acrylic acid (AA), vinylpyrrolidone (VP), dimethylacrylamide (DMAA) and diethylacrylamide (DEAA) is preferred, and N -Isopropylacrylamide (NIPAM) is more preferred.

  In the case where the water-soluble polymer compound (component A) 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 I The arrangement in the copolymer of structural units other than may be block or random.

  Specific examples of the water-soluble polymer compound (component A) include, for example, HEAA homopolymer, HMAA homopolymer, HEAA and HMAA copolymer, HEAA and NIPAM copolymer, and HMAA and NIPAM copolymer. , HEAA / HMAA / NIPAM copolymer, HEAA / MAA copolymer, HEAA / AA copolymer, HEAA / VP copolymer, HEAA / DMAA copolymer, HEAA / DEAA copolymer , HMAA and MAA copolymer, HMAA and AA copolymer, HMAA and VP copolymer, HMAA and DMAA copolymer, and HMAA and DEAA copolymer. And HEAA homopolymers, HMAA homopolymers, and copolymers of HEAA and HMAA are more preferable from the viewpoint of reducing the surface roughness. AA homopolymer is more preferred.

  The weight average molecular weight of the water-soluble polymer compound (component A) is from 150,000 to 1,500,000 from the viewpoint of reducing surface defects and surface roughness of the silicon wafer, but reducing the surface defects and surface roughness of the silicon wafer. In view of the above, 200,000 or more are preferable, 250,000 or more are more preferable, 300,000 or more are more preferable, the viewpoint of reducing surface defects and surface roughness of the silicon wafer surface, and improvement of the storage stability of the polishing composition. From the viewpoint, 1.2 million or less is preferable, 1 million or less is more preferable, 800,000 or less is more preferable, and 500,000 or less is more preferable. The weight average molecular weight of the water-soluble polymer compound (component A) is measured by the method described in the examples below.

  The content of the water-soluble polymer compound (component A) contained in the polishing liquid composition of the present invention is 0.001 from the viewpoint of reducing surface defects (LPD) and surface roughness (haze) of the silicon wafer. % By mass or more is preferable, 0.002% by mass or more is more preferable, 0.004% by mass or more is further preferable, and 0.007% by mass or more is further more preferable. Further, the content of the water-soluble polymer compound (component A) is preferably 0.05% by mass or less from the viewpoint of reducing the surface roughness (haze) of the silicon wafer surface and improving the storage stability. 0.035 mass% or less is more preferable, 0.025 mass% or less is more preferable, and 0.015 mass% or less is still more preferable.

  Mass ratio of water-soluble polymer compound (component A) and silica particles (component D) contained in the polishing composition of the present invention (mass of water-soluble polymer compound (component A) / mass of silica particles (component D)) ) Is preferably 0.005 or more, more preferably 0.01 or more, still more preferably 0.02 or more, from the viewpoint of improving the dispersibility of the silica particles and reducing the surface defects and surface roughness of the silicon wafer. 025 or more is still more preferable, 0.035 or more is further more preferable, 0.20 or less is preferable, 0.14 or less is more preferable, 0.10 or less is further preferable, and 0.08 or less is even more preferable. 0.06 or less is even more preferable.

[Polyhydric alcohol alkylene oxide adduct (component B)]
The polyhydric alcohol alkylene oxide adduct is a polyhydric alcohol derivative obtained by addition polymerization of an alkylene oxide such as ethylene oxide or propylene oxide to a polyhydric alcohol. The polishing composition of the present invention contains a polyhydric alcohol alkylene oxide adduct having a weight average molecular weight of 500 or more and 250,000 or less from the viewpoint of reducing surface defects and surface roughness of a silicon wafer. The polyhydric alcohol alkylene oxide adduct contains at least one alkylene oxide group selected from the group consisting of an ethyleneoxy group and a propyleneoxy group.

  The weight average molecular weight of the polyhydric alcohol ethylene oxide adduct (component B) is 500 or more from the viewpoint of reducing surface defects and surface roughness of the silicon wafer, preferably 1000 or more, more preferably 1200 or more, and 2000 or more. Is more preferably 4000 or more, and from the viewpoint of reducing surface defects and surface roughness of the silicon wafer and improving the storage stability of the polishing composition, it is 250,000 or less, preferably 220,000 or less. 180,000 or less, more preferably 50,000 or less, even more preferably 30,000 or less, and even more preferably 10,000 or less.

  The number of hydroxyl groups of the polyhydric alcohol, which is the source (raw material) of the polyhydric alcohol alkylene oxide adduct (component B), increases the adsorption strength of the polyhydric alcohol alkylene oxide adduct on the silicon wafer surface, and surface defects of the silicon wafer. And from the viewpoint of reducing the surface roughness, 2 or more are preferable, and from the viewpoint of securing the polishing rate, 10 or less are preferable, 8 or less are more preferable, 6 or less are even more preferable, and 4 or less are further Is more preferable.

  Specific examples of the polyhydric alcohol alkylene oxide adduct (component B) include an ethylene glycol alkylene oxide adduct, a glycerin alkylene oxide adduct, a pentaerythritol alkylene oxide adduct, and the like. Preference is given to glycerin alkylene oxide adducts and pentaerythritol alkylene oxide adducts which have a small molecular size and therefore a high adsorption rate on the silicon wafer surface.

  The polyhydric alcohol alkylene oxide adduct contains at least one alkylene oxide group selected from the group consisting of ethyleneoxy groups (EO) and propyleneoxy groups (PO), but reduces the surface defects and surface roughness of silicon wafers. In view of the above, the alkylene oxide group contained in the polyhydric alcohol alkylene oxide adduct is preferably composed of at least one alkylene oxide group selected from the group consisting of EO and PO, and more preferably composed of EO. When the polyhydric alcohol alkylene oxide adduct contains both EO and PO, the sequence of EO and PO may be block or random. From the viewpoint of reducing surface defects and surface roughness of the silicon wafer, the average added mole number of EO is preferably 10 or more, more preferably 20 or more, still more preferably 50 or more, still more preferably 100 or more, and 5000 The following is preferable, 2000 or less is more preferable, 800 or less is further preferable, 200 or less is further more preferable, and the average added mole number of PO is preferably 10 or more, more preferably 20 or more, still more preferably 50 or more, 5000 or less is preferable, 2000 or less is more preferable, 800 or less is further preferable, and 200 or less is even more preferable.

  The content of the polyhydric alcohol alkylene oxide adduct (component B) contained in the polishing composition of the present invention is preferably 0.00001% by mass or more from the viewpoint of reducing surface defects and surface roughness of the silicon wafer, 0.0003 mass% or more is more preferable, and 0.0005 mass% or more is still more preferable. The content of the polyhydric alcohol alkylene oxide adduct (component B) is preferably 0.005% by mass or less, more preferably 0.0020% by mass or less, and 0.0018% by mass from the viewpoint of ensuring the polishing rate. The following is more preferable.

  The mass ratio of polyhydric alcohol alkylene oxide adduct (component B) to silica particles (component D) contained in the polishing composition of the present invention (mass of polyhydric alcohol alkylene oxide adduct / mass of silica particles) is silicon. From the viewpoint of reducing surface defects and surface roughness of the wafer, 0.00004 or more is preferable, 0.0012 or more is more preferable, 0.002 or more is further preferable, 0.02 or less is preferable, and 0.0080 or less is preferable. Is more preferable, and 0.0072 or less is still more preferable.

  Mass ratio of water-soluble polymer compound (component A) and polyhydric alcohol alkylene oxide adduct (component B) contained in the polishing composition of the present invention (mass of water-soluble polymer compound / polyhydric alcohol alkylene oxide adduct) Is preferably 1 or more, more preferably 3 or more, further preferably 5 or more, preferably 200 or less, more preferably 100 or less, from the viewpoint of reducing surface defects and surface roughness of the silicon wafer. 60 or less is more preferable, and 40 or less is still more preferable.

[Nitrogen-containing basic compound (component C)]
The polishing liquid composition of the present invention contains a water-soluble basic compound from the viewpoint of improving the storage stability of the polishing liquid composition and reducing the surface defects and surface roughness of the silicon wafer. 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, and “water-soluble basic compound” means a compound that shows basicity when dissolved in water. .

  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, and tetramethylammonium and the like hydroxide. These nitrogen-containing basic compounds may be used as a mixture of two or more. As the nitrogen-containing basic compound that can be contained in the polishing liquid composition of the present invention, ammonia is more preferable from the viewpoint of reducing surface defects and surface roughness of the silicon wafer.

  The content of the nitrogen-containing basic compound contained in the polishing liquid composition of the present invention is the viewpoint of reducing the surface defects and surface roughness of the silicon wafer, improving the storage stability of the polishing liquid composition, and ensuring the polishing rate. Therefore, 0.001 mass% or more is preferable, 0.003 mass% or more is more preferable, 0.005 mass% or more is further preferable, and 0.007 mass% or more is further more preferable. Further, from the viewpoint of reducing surface defects and surface roughness of the silicon wafer, 1% by mass or less is preferable, 0.1% by mass or less is more preferable, 0.05% by mass or less is further preferable, and 0.03% by mass or less. Is even more preferred.

[Silica particles (component D)]
The polishing composition of the present invention contains silica particles as an abrasive. Specific examples of the silica particles include colloidal silica and fumed silica, but colloidal silica is more preferable from the viewpoint of reducing surface defects and surface roughness 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 polishing composition of the present invention is colloidal silica, colloidal silica is obtained from a hydrolyzate of alkoxysilane from the viewpoint of preventing contamination of the silicon wafer by alkali metal or alkaline earth metal. It is preferable that Silica particles obtained from the hydrolyzate of alkoxysilane can be produced by a conventionally known method.

  The average primary particle diameter of the silica particles contained in the polishing liquid composition of the present invention is preferably 5 nm or more, more preferably 10 nm or more, still more preferably 15 nm or more, and even more preferably 30 nm or more, from the viewpoint of ensuring the polishing rate. preferable. The average primary particle diameter of the silica particles is preferably 50 nm or less, more preferably 45 nm or less, and still more preferably 40 nm or less, from the viewpoints of ensuring the polishing rate and reducing the surface defects and surface roughness of the silicon wafer.

  In particular, when colloidal silica is used as the silica particles, the average primary particle diameter is preferably 5 nm or more and more preferably 10 nm or more from the viewpoint of ensuring the polishing rate and reducing the surface defects and surface roughness of the silicon wafer. Preferably, 15 nm or more is more preferable, 30 nm or more is further more preferable, 50 nm or less is preferable, 45 nm or less is more preferable, and 40 nm or less is still more preferable.

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 1.1 or more, more preferably 1.8 or more, further preferably 2.0 or more, and 3.0 from the viewpoint of reducing surface defects and surface roughness of the silicon wafer. The following is preferable, 2.5 or less is more preferable, and 2.3 or less is 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 1.1 or more, and more preferably 1.8 or more, from the viewpoint of ensuring the polishing rate and reducing the surface roughness and surface defects of the silicon wafer surface. 2.0 or more is more preferable, 3.0 or less is preferable, 2.5 or less is more preferable, and 2.3 or less is 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 contained in the polishing liquid composition of the present invention is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, and more preferably 0.2% by mass or more from the viewpoint of ensuring the polishing rate. Is more preferable. Moreover, 10 mass% or less is preferable from a viewpoint of economical efficiency, 7.5 mass% or less is more preferable, 5 mass% or less is still more preferable, 1 mass% or less is still more preferable, 0.5 mass% or less is still more preferable. preferable.

[Aqueous medium (component E)]
Examples of the aqueous medium (component E) contained in the polishing composition of the present invention include water such as ion-exchanged water and ultrapure water, or a mixed medium of water and a solvent. A miscible solvent (for example, an alcohol such as ethanol) is preferred. As the aqueous medium, ion-exchanged water or ultrapure water is more preferable, and ultrapure water is more preferable. When the component E of the present invention is a mixed medium of water and a solvent, the ratio of water to the entire mixed medium as the component E 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, substantially 100 mass% is still more preferable, and 100 mass% is still more preferable.

  The content of the aqueous medium in the polishing liquid composition of the present invention is not particularly limited, and may be the remainder of components A to D and optional components described below.

  The pH of the polishing composition of the present invention at 25 ° C. is preferably 8.0 or more, more preferably 9.0 or more, from the viewpoint of ensuring the polishing rate and the reduction of surface defects and surface roughness of the silicon wafer. 9.5 or more is more preferable, 12.0 or less is preferable, 11.5 or less is more preferable, and 11.0 or less is still more preferable. The pH can be adjusted by appropriately adding a pH adjusting agent (for example, ammonia). 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 composition of the present invention, a water-soluble polymer compound other than the water-soluble polymer compound (component A), a pH adjuster, an antiseptic, an alcohol, a chelate, as long as the effects of the present invention are not hindered. At least one optional component selected from an agent and a nonionic surfactant may be contained.

<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-propanool, ethylene glycol, propylene glycol, polyethylene glycol, and glycerin. The content of alcohol in the polishing composition of the present invention is preferably 0.1% by mass or more and 5% by mass or less.

<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 in the polishing composition of the present invention is preferably 0.01% by mass or more and 1% by mass or less.

<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.

  In addition, although content of each component demonstrated in the above is content at the time of use, the polishing liquid composition of this invention is in the range which the storage stability is not impaired from a viewpoint of economical efficiency and operativity. It may be stored and supplied in a concentrated state. In this case, it is preferable in that the production and transportation costs can be further reduced. The concentrate may be used after appropriately diluted with the above-mentioned aqueous medium as necessary. The concentration factor is not particularly limited as long as the concentration at the time of polishing after dilution can be secured, but is preferably 2 times or more, more preferably 10 times or more, and more preferably 20 times or more from the viewpoint of economy and operability. Is more preferable, 30 times or more is more preferable, 80 times or less is preferable, 60 times or less is more preferable, 50 times or less is more preferable, and 45 times or less is even more preferable.

  When the polishing liquid composition of the present invention is the concentrated liquid, the content of the water-soluble polymer compound (component A) in the concentrated liquid is preferably 0.08% by mass or more from the viewpoint of economy and operability. 0.16 mass% or more is more preferable, 0.28 mass% or more is still more preferable, 0.3 mass% or more is still more preferable, and 0.35 mass% or more is still more preferable. The content of the water-soluble polymer compound (component A) in the concentrated solution is preferably 5.0% by mass or less, more preferably 1.4% by mass or less, from the viewpoint of improving storage stability. 0 mass% or less is still more preferable, and 0.6 mass% or less is still more preferable.

  When the polishing liquid composition of the present invention is the concentrated liquid, the content of the polyhydric alcohol alkylene oxide adduct (component B) in the concentrated liquid is 0.0004% by mass or more from the viewpoint of economy and operability. Preferably, 0.004 mass% or more is more preferable, 0.012 mass% or more is further preferable, and 0.02 mass% or more is still more preferable. In addition, the content of the polyhydric alcohol alkylene oxide adduct (component B) in the concentrate is preferably 0.2% by mass or less, more preferably 0.080% by mass or less, from the viewpoint of improving storage stability. 0.072% by mass or less is more preferable.

  When the polishing liquid composition of the present invention is the concentrated liquid, the content of the nitrogen-containing basic compound (component C) in the concentrated liquid is preferably 0.04% by mass or more from the viewpoint of economy and operability. 0.12 mass% or more is more preferable, 0.2 mass% or more is still more preferable, and 0.28 mass% or more is still more preferable. Further, the content of the nitrogen-containing basic compound (component C) in the concentrate is preferably 40% by mass or less, and preferably 4% by mass or less from the viewpoint of improving storage stability, from the viewpoint of improving storage stability. More preferably, 2% by mass or less is further preferable, and 1.2% by mass or less is even more preferable.

  When the polishing liquid composition of the present invention is the concentrated liquid, the content of silica particles (component D) in the concentrated liquid is preferably 2% by mass or more from the viewpoint of economy and operability, and is 4% by mass or more. More preferably, 8 mass% or more is still more preferable. Further, the content of silica particles in the concentrate is preferably 40% by mass or less, more preferably 30% by mass or less, still more preferably 20% by mass or less, and further preferably 15% by mass or less from the viewpoint of improving storage stability. Further preferred.

  Next, an example of the manufacturing method of the polishing composition of the present invention will be described.

  An example of the manufacturing method of the polishing composition of the present invention is not limited at all. For example, a water-soluble polymer compound (component A), a polyhydric alcohol alkylene oxide adduct (component B), and a nitrogen-containing basic compound. It can be prepared by mixing (Component C), silica particles (Component D), an aqueous medium (Component E), and optional components as necessary.

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

  The polishing composition of the present invention is used in, for example, a polishing process for polishing a silicon wafer and a polishing method for a silicon wafer including a polishing process for polishing a silicon wafer in the process of manufacturing a semiconductor substrate such as a bare wafer.

  In the polishing process for polishing the silicon wafer, a lapping (rough polishing) process for flattening the silicon wafer obtained by slicing a silicon single crystal ingot into a thin disk shape, and etching the lapped silicon wafer Thereafter, there is a finish polishing step for 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 and the silicon wafer polishing method may include a dilution step of diluting the polishing composition (concentrate) of the present invention before the polishing step of polishing the silicon wafer. An aqueous medium (component E) may be used as the diluent.

  The concentrated solution diluted in the dilution step is, for example, from 0.35 mass% to 0.6 mass% in component A and 0.02 in component B from the viewpoints of production and transportation cost reduction and storage stability improvement. It is preferable to contain not less than mass% and not more than 0.072 mass%, component C in an amount of not less than 0.28 mass% and not more than 1.2 mass%, and component D in an amount of not less than 8 mass% and not more than 15 mass%.

  The present invention further discloses the following <1> to <20>.

ただし、一般式（１）において、Ｒ¹は炭素数１〜２のヒドロキシアルキル基である。
＜２＞
前記水溶性高分子化合物の全構成単位中における前記構成単位Ｉの割合は、８０質量％以上が好ましく、９０質量％以上がより好ましく、実質的に１００質量％がさらに好ましく、１００質量％がさらにより好ましい、前記＜１＞に記載のシリコンウェーハ用研磨液組成物。
＜３＞
前記水溶性高分子化合物が、前記構成単位Ｉ以外の構成単位IIとして、好ましくはＮ−
イソプロピルアクリルアミド（ＮＩＰＡＭ）、メタクリル酸(ＭＡＡ)、アクリル酸（ＡＡ）、ビニルピロリドン（ＶＰ），ジメチルアクリルアミド（ＤＭＡＡ）およびジエチルアクリルアミド（ＤＥＡＡ）からなる群から選ばれる少なくとも一種のモノマーに由来する構成単位、より好ましくはＮ−イソプロピルアクリルアミド（ＮＩＰＡＭ）を含む、前記＜１＞又は＜２＞に記載のシリコンウェーハ用研磨液組成物。
＜４＞
前記水溶性高分子化合物の重量平均分子量は、２０万以上が好ましく、２５万以上がより好ましく、３０万以上が更に好ましく、１２０万以下が好ましく、１００万以下がより好ましく、８０万以下が更に好ましく、５０万以下がより更に好ましい、前記＜１＞から＜３＞のいずれかに記載のシリコンウェーハ用研磨液組成物。
＜５＞
前記シリコンウェーハ用研磨液組成物における前記水溶性高分子化合物の含有量は、好ましくは０．００１質量％以上０．０５質量％以下であって、０．００２質量％以上がより好ましく、０．００４質量％以上が更に好ましく、０．００７質量％以上がより更に好ましく、０．０３５質量％以下がより好ましく、０．０２５質量％以下が更に好ましく、０．０１５質量％以下がより更に好ましい、前記＜１＞から＜４＞のいずれかに記載のシリコンウェーハ用研磨液組成物。
＜６＞
前記シリコンウェーハ用研磨液組成物に含まれる前記水溶性高分子化合物とシリカ粒子の質量比（水溶性高分子化合物の質量／シリカ粒子の質量）は、０．００５以上が好ましく、０．０１以上がより好ましく、０．０２以上が更に好ましく、０．０２５以上が更により好ましく、０．０３５以上が更により好ましく、０．２０以下が好ましく、０．１４以下がより好ましく、０．１０以下が更に好ましく、０．０８以下が更により好ましく、０．０６以下が更により好ましい、前記＜１＞から＜５＞のいずれかに記載のシリコンウェーハ用研磨液組成物。
＜７＞
前記多価アルコールエチレンオキシド付加物の重量平均分子量は、１０００以上が好ましく、１２００以上がより好ましく、２０００以上が更に好ましく、４０００以上が更により好ましく、２２万以下が好ましく、１８万以下がより好ましく、５万以下が更に好ましく、３万以下が更により好ましく、１万以下が更により好ましい、前記＜１＞から＜６＞のいずれかに記載のシリコンウェーハ用研磨液組成物。
＜８＞
前記多価アルコールアルキレンオキシド付加物は、多価アルコールにアルキレンオキシドを付加重合させて得られたものであり、好ましくは前記多価アルコールは１分子内に水酸基を３つ以上有し、１０個以下が好ましく、８個以下がより好ましく、６個以下が更により好ましく、４個以下が更により好ましい、前記＜１＞から＜７＞のいずれかに記載のシリコンウェーハ用研磨液組成物。
＜９＞
多価アルコールアルキレンオキシド付加物に含まれるアルキレンオキシド基は、エチレンオキシ基（ＥＯ）およびプロピレンオキシ基（ＰＯ）からなる群から選ばれる少なくとも１種のアルキレンオキシド基からなると好ましく、ＥＯからなるとより好ましい、前記＜１＞から＜８＞のいずれかに記載のシリコンウェーハ用研磨液組成物。
＜１０＞
多価アルコールアルキレンオキシド付加物に含まれるアルキレンオキシド基はＥＯからなり、ＥＯの平均付加モル数は、１０以上が好ましく、２０以上がより好ましく、５０以上が更に好ましく、１００以上が更により好ましく、また、５０００以下が好ましく、２０００以下がより好ましく、８００以下が更に好ましく、２００以下が更により好ましい、前記＜９＞に記載のシリコンウェーハ用研磨液組成物。
＜１１＞
前記シリコンウェーハ用研磨液組成物における前記多価アルコールアルキレンオキシド付加物の含有量が、好ましくは０．００００１質量％以上０．００５質量％以下であって、０．０００３質量％以上がより好ましく、０．０００５質量％以上が更に好ましく、０．００２０質量％以下がより好ましく、０．００１８質量％以下が更に好ましい、前記＜１＞から＜１０＞のいずれかに記載のシリコンウェーハ用研磨液組成物。
＜１２＞
前記シリコンウェーハ用研磨液組成物に含まれる、前記多価アルコールアルキレンオキシド付加物と前記シリカ粒子の質量比（多価アルコールアルキレンオキシド付加物の質量／シリカ粒子の質量）は、０．００００４以上が好ましく、０．００１２以上がより好ましく、０．００２以上が更に好ましく、０．０２以下が好ましく、０．００８０以下がより好ましく、０．００７２以下が更に好ましい、前記＜１＞から＜１１＞のいずれかに記載のシリコンウェーハ用研磨液組成物。
＜１３＞
前記シリコンウェーハ用研磨液組成物に含まれる、前記水溶性高分子化合物と前記多価アルコールアルキレンオキシド付加物の質量比（水溶性高分子化合物の質量／多価アルコールアルキレンオキシド付加物の質量）は、１以上が好ましく、３以上がより好ましく、５以上が更に好ましく、２００以下が好ましく、１００以下がより好ましく、６０以下が更に好ましい、前記＜１＞から＜１２＞のいずれかに記載のシリコンウェーハ用研磨液組成物。
＜１４＞
前記シリコンウェーハ用研磨液組成物における前記含窒素塩基性化合物の含有量は、０．００１質量％以上が好ましく、０．００３質量％以上がより好ましく、０．００５質量％以上が更に好ましく、０．００７質量％以上がより更に好ましく、１質量％以下が好ましく、０．１質量％以下がより好ましく、０．０５質量％以下が更に好ましく、０．０３質量％以下が更により好ましい、前記＜１＞から＜１３＞のいずれかに記載のシリコンウェーハ用研磨液組成物。
＜１５＞
前記シリカ粒子の平均一次粒子径は、好ましくは５ｎｍ以上５０ｎｍ以下であって、１０ｎｍ以上がより好ましく、１５ｎｍ以上が更に好ましく、３０ｎｍ以上が更により好ましく、４５ｎｍ以下がより好ましく、４０ｎｍ以下が更に好ましい、前記＜１＞から＜１４＞のいずれかに記載のシリコンウェーハ用研磨液組成物。
＜１６＞
前記＜１＞から＜１５＞のいずれかに記載のシリコンウェーハ用研磨液組成物を用いてシリコンウェーハを研磨する工程を含む半導体基板の製造方法。
＜１７＞
前記研磨工程において、濃縮された前記シリンウェーハ用研磨液組成物を希釈してから
前記シリコンウェーハの研磨に使用する、前記＜１６＞に記載の半導体基板の製造方法。
＜１８＞
濃縮された前記シリンウェーハ用研磨液組成物の希釈倍率は、２倍以上が好ましく、１０倍以上がより好ましく、２０倍以上が更に好ましく、３０倍以上がさらにより好ましく、８０倍以下が好ましく、６０倍以下がより好ましく、５０倍以下が更に好ましく、４５倍以下がさらにより好ましい、前記＜１７＞に記載の半導体基板の製造方法。
＜１９＞
濃縮された前記シリンウェーハ用研磨液組成物は、前記水溶性高分子化合物を０．３５質量％以上０．６質量％以下、前記多価アルコールアルキレンオキシド付加物を０．０２質量％以上０．０７２質量％以下、前記含窒素塩基性化合物を０．２８質量％以上１．２質量％以下、前記シリカ粒子を８質量％以上１５質量％以下含む、前記＜１７＞または＜１８＞に記載の半導体基板の製造方法。
＜２０＞
前記＜１＞から＜１５＞のいずれかに記載のシリコンウェーハ用研磨液組成物を用いてシリコンウェーハを研磨する研磨工程を含む、シリコンウェーハの研磨方法。 <1>
Silica particles;
A nitrogen-containing basic compound and a water-soluble polymer compound containing 75% by mass or more of a structural unit represented by the following general formula (1) and having a weight average molecular weight of 150,000 to 1,500,000,
A polyhydric alcohol alkylene oxide adduct having a weight average molecular weight of 500 to 250,000,
An aqueous medium,
The polyhydric alcohol alkylene oxide adduct contains at least one alkylene oxide group selected from the group consisting of an ethyleneoxy group and a propyleneoxy group.
Polishing liquid composition for silicon wafers.

However, in the general formula (1), R ¹ is a hydroxyalkyl group having 1 to 2 carbon atoms.
<2>
The proportion of the structural unit I in all structural units of the water-soluble polymer compound is preferably 80% by mass or more, more preferably 90% by mass or more, substantially more preferably 100% by mass, and further more preferably 100% by mass. More preferably, the polishing composition for a silicon wafer according to <1>.
<3>
The water-soluble polymer compound is preferably N— as the structural unit II other than the structural unit I.
A structural unit derived from at least one monomer selected from the group consisting of isopropylacrylamide (NIPAM), methacrylic acid (MAA), acrylic acid (AA), vinylpyrrolidone (VP), dimethylacrylamide (DMAA) and diethylacrylamide (DEAA) More preferably, the polishing composition for a silicon wafer according to the above <1> or <2>, comprising N-isopropylacrylamide (NIPAM).
<4>
The water-soluble polymer compound has a weight average molecular weight of preferably 200,000 or more, more preferably 250,000 or more, further preferably 300,000 or more, preferably 1,200,000 or less, more preferably 1,000,000 or less, and more preferably 800,000 or less. The polishing composition for a silicon wafer according to any one of <1> to <3>, preferably 500,000 or less.
<5>
The content of the water-soluble polymer compound in the polishing composition for a silicon wafer is preferably 0.001% by mass or more and 0.05% by mass or less, more preferably 0.002% by mass or more. 004% by mass or more is more preferable, 0.007% by mass or more is more preferable, 0.035% by mass or less is more preferable, 0.025% by mass or less is further preferable, and 0.015% by mass or less is more preferable. The polishing composition for a silicon wafer according to any one of <1> to <4>.
<6>
The mass ratio of the water-soluble polymer compound to silica particles (mass of water-soluble polymer compound / mass of silica particles) contained in the silicon wafer polishing composition is preferably 0.005 or more, and 0.01 or more. Is more preferably 0.02 or more, still more preferably 0.025 or more, still more preferably 0.035 or more, preferably 0.20 or less, more preferably 0.14 or less, and 0.10 or less. More preferably, 0.08 or less is still more preferable, 0.06 or less is still more preferable, The polishing composition for silicon wafers in any one of said <1> to <5>.
<7>
The polyhydric alcohol ethylene oxide adduct has a weight average molecular weight of preferably 1000 or more, more preferably 1200 or more, still more preferably 2000 or more, still more preferably 4000 or more, preferably 220,000 or less, more preferably 180,000 or less, 50,000 or less is still more preferable, 30,000 or less is still more preferable, and 10,000 or less is still more preferable, The polishing liquid composition for silicon wafers in any one of said <1> to <6>.
<8>
The polyhydric alcohol alkylene oxide adduct is obtained by addition polymerization of an alkylene oxide to a polyhydric alcohol. Preferably, the polyhydric alcohol has 3 or more hydroxyl groups in one molecule and 10 or less. The polishing composition for a silicon wafer according to any one of <1> to <7>, wherein 8 or less is more preferable, 6 or less is even more preferable, and 4 or less is even more preferable.
<9>
The alkylene oxide group contained in the polyhydric alcohol alkylene oxide adduct is preferably composed of at least one alkylene oxide group selected from the group consisting of ethyleneoxy group (EO) and propyleneoxy group (PO), and more preferably composed of EO. The polishing composition for a silicon wafer according to any one of <1> to <8>.
<10>
The alkylene oxide group contained in the polyhydric alcohol alkylene oxide adduct is composed of EO, and the average added mole number of EO is preferably 10 or more, more preferably 20 or more, still more preferably 50 or more, still more preferably 100 or more, Moreover, 5000 or less are preferable, 2000 or less are more preferable, 800 or less are still more preferable, 200 or less are further more preferable, The polishing liquid composition for silicon wafers as described in said <9>.
<11>
The content of the polyhydric alcohol alkylene oxide adduct in the polishing composition for a silicon wafer is preferably 0.00001 mass% or more and 0.005 mass% or less, more preferably 0.0003 mass% or more, 0.0005 mass% or more is still more preferable, 0.0020 mass% or less is more preferable, 0.0018 mass% or less is still more preferable, The polishing liquid composition for silicon wafers in any one of said <1> to <10> object.
<12>
The mass ratio of the polyhydric alcohol alkylene oxide adduct and the silica particles (mass of polyhydric alcohol alkylene oxide adduct / mass of silica particles) contained in the silicon wafer polishing composition is 0.00004 or more. Preferably, 0.0012 or more is more preferable, 0.002 or more is further preferable, 0.02 or less is preferable, 0.0080 or less is more preferable, and 0.0072 or less is further preferable, <1> to <11> The polishing composition for silicon wafers according to any one of the above.
<13>
The mass ratio of the water-soluble polymer compound to the polyhydric alcohol alkylene oxide adduct (mass of water-soluble polymer compound / mass of polyhydric alcohol alkylene oxide adduct) contained in the polishing composition for silicon wafer is: 1 or more, 3 or more is more preferable, 5 or more is more preferable, 200 or less is preferable, 100 or less is more preferable, and 60 or less is still more preferable, The silicon according to any one of <1> to <12> Polishing liquid composition for wafers.
<14>
The content of the nitrogen-containing basic compound in the polishing composition for a silicon wafer is preferably 0.001% by mass or more, more preferably 0.003% by mass or more, still more preferably 0.005% by mass or more, 0 0.007% by mass or more is more preferable, 1% by mass or less is preferable, 0.1% by mass or less is more preferable, 0.05% by mass or less is further preferable, and 0.03% by mass or less is even more preferable. The polishing composition for silicon wafers according to any one of <1> to <13>.
<15>
The average primary particle diameter of the silica particles is preferably 5 nm or more and 50 nm or less, more preferably 10 nm or more, further preferably 15 nm or more, still more preferably 30 nm or more, more preferably 45 nm or less, still more preferably 40 nm or less. The polishing composition for a silicon wafer according to any one of <1> to <14>.
<16>
The manufacturing method of a semiconductor substrate including the process of grind | polishing a silicon wafer using the polishing liquid composition for silicon wafers in any one of said <1> to <15>.
<17>
The method for producing a semiconductor substrate according to <16>, wherein in the polishing step, the concentrated polishing composition for silicon wafer is diluted and then used for polishing the silicon wafer.
<18>
The dilution ratio of the concentrated polishing composition for a silicon wafer is preferably 2 times or more, more preferably 10 times or more, still more preferably 20 times or more, still more preferably 30 times or more, and preferably 80 times or less, The method for producing a semiconductor substrate according to <17>, wherein 60 times or less is more preferable, 50 times or less is more preferable, and 45 times or less is even more preferable.
<19>
In the concentrated polishing liquid composition for a silicon wafer, the water-soluble polymer compound is 0.35% by mass to 0.6% by mass, and the polyhydric alcohol alkylene oxide adduct is 0.02% by mass to 0.00%. 072% by mass or less, 0.28% by mass or more and 1.2% by mass or less of the nitrogen-containing basic compound, and 8% by mass or more and 15% by mass or less of the silica particles according to the above <17> or <18>. A method for manufacturing a semiconductor substrate.
<20>
A method for polishing a silicon wafer, comprising a polishing step of polishing the silicon wafer using the polishing composition for a silicon wafer according to any one of <1> to <15>.

<Synthesis of water-soluble polymer compound (component A)>
The water-soluble polymer compounds used in the following Examples 1 to 39 and Comparative Examples 1 to 12 were synthesized as follows.

(Water-soluble polymer compound No. 1)
[HEAA homopolymer, weight average molecular weight 1.38 million]
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-shaped Teflon stirring blade, the inside of the separable flask was purged with nitrogen. Subsequently, after raising the temperature in the separable flask to 65 ° C. using an oil bath, a monomer aqueous solution and a polymerization initiator aqueous solution prepared in advance were dropped over 3.5 hours to carry out polymerization. After completion of dropping, the temperature and stirring were maintained for 4 hours to obtain 1500 g of a colorless and transparent 10% polyhydroxyethylacrylamide aqueous solution.

(Water-soluble polymer compound No. 2)
[HEAA homopolymer, weight average molecular weight 430,000]
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 stirring blade, the inside of the separable flask was purged with nitrogen. Next, after the temperature in the separable flask was raised to 75 ° 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 dropping, the temperature and stirring were maintained for 4 hours to obtain 1500 g of a colorless and transparent 10% polyhydroxyethylacrylamide aqueous solution.

(Water-soluble polymer compound No. 3)
[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-shaped Teflon 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 dropping, the temperature and stirring were maintained for 4 hours to obtain 1500 g of a colorless and transparent 10% polyhydroxyethylacrylamide aqueous solution.

(Water-soluble polymer compound No. 4)
[HEAA homopolymer, weight average molecular weight 240,000]
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-shaped Teflon stirring blade, the inside of the separable flask was purged with nitrogen. Next, the temperature in the separable flask was raised to 82 ° C. using an oil bath, and then a monomer aqueous solution and a polymerization initiator aqueous solution prepared in advance were added dropwise over 3.5 hours to carry out polymerization. After completion of dropping, the temperature and stirring were maintained for 4 hours to obtain 1500 g of a colorless and transparent 10% polyhydroxyethylacrylamide aqueous solution.

(Water-soluble polymer compound No. 5)
[HEAA homopolymer, weight average molecular weight 110,000]
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, 0.12 g of 2,2'-azobis (2-methylpropionamidine) dihydrochloride (polymerization initiator, V-50 6.50 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-shaped Teflon stirring blade, the inside of the separable flask was purged with nitrogen. Next, after the temperature in the separable flask was raised to 75 ° 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 dropping, the temperature and stirring were maintained for 4 hours to obtain 1500 g of a colorless and transparent 10% polyhydroxyethylacrylamide aqueous solution.

(Water-soluble polymer compound No. 6)
[HEAA homopolymer, weight average molecular weight of 1.5 million or more]
In a 500 ml beaker, hydroxyethyl acrylamide (HEAA) 15 g (0.13 mol manufactured by Kojin) and 2,2'-azobis (2-methylpropionamidine) dihydrochloride 0.035 g (polymerization initiator, V-50 0.13 mmol Wako Pure) Yakuhin) was dissolved in 285 g of ion exchange water to prepare an aqueous monomer solution. After replacing the inside of a 500 ml separable flask equipped with a thermometer and a 5 cm crescent moon type Teflon stirring blade with nitrogen, 1/10 of the monomer aqueous solution was placed in the separable flask, and the temperature of the ion exchange water was adjusted using an oil bath. The temperature was raised to 55 ° C. to obtain a reaction solution. After confirming the thickening of the reaction solution, the remaining monomer solution was added dropwise to the reaction solution over 5 hours for polymerization. After completion of the dropwise addition, the mixture was stirred for 1 hour, further heated to 65 ° C., and then stirred for 2 hours. As a result, 300 g of a colorless and transparent 5% polyhydroxyethylacrylamide aqueous solution was obtained.

Moreover, the detail of the water-soluble polymer compound used by Comparative Examples 13-17 as a comparison object of a water-soluble polymer compound (component A) is as follows.
(Water-soluble polymer compound No. 7)
HEC (hydroxyethylcellulose): Mw 1.2 million (catalog value) (manufactured by Sumitomo Seika Co., Ltd.)
(Water-soluble polymer compound No. 8)
HEC (hydroxyethyl cellulose): Mw 250,000 (catalog value) (manufactured by Daicel Corporation)
(Water-soluble polymer compound No. 9)
PVA (polyvinyl alcohol): Mw 1700 (catalog value) (manufactured by Wako Pure Chemical Industries, reagent)
(Water-soluble polymer compound No. 10)
HEC (hydroxyethylcellulose): Mw 800,000 (catalog value) (manufactured by Sumitomo Seika Co., Ltd.)

The details of the polyhydric alcohol alkylene oxide adducts used in Examples 1 to 39 and Comparative Examples 1 to 14 below are as follows. The “alcohol structure” described in Table 1 and Table 2 means the structure of the polyhydric alcohol that is the source (raw material) of the polyhydric alcohol alkylene oxide adduct, “PE” represents pentaerythritol, “Gly” Means glycerin and “EG” means ethylene glycol.
(No.1)
EO adduct of pentaerythritol (EO average addition mole number = 140, manufactured by Nippon Emulsifier Co., Ltd.)
(No.2)
EO adduct of pentaerythritol (EO average addition mole number = 20, manufactured by Nippon Emulsifier Co., Ltd.)
(No.3)
EO adduct of pentaerythritol (EO average addition mole number = 450, manufactured by Nippon Emulsifier Co., Ltd.)
(No.4)
EO adduct of glycerin (EO average addition mole number = 20, manufactured by Kao Corporation)
(No.5)
Glycerin EO adduct (average number of added EO = 26, manufactured by Kao Corporation)
(No.6)
Glycerin EO adduct (EO average addition mole number = 120, manufactured by Kao Corporation)
(No.7)
EO adduct of ethylene glycol (EO addition mole number = 25, polyethylene glycol, Mw1000 (catalog value), Wako first grade, manufactured by Wako Pure Chemical Industries)
(No.8)
EO adduct of ethylene glycol (EO addition mole number = 150, polyethylene glycol, Mw6000 (catalog value), Wako first grade, Wako Pure Chemical Industries, Ltd.)
(No.9)
EO adduct of ethylene glycol (EO average addition mole number = 500, polyethylene glycol, Mw20000 (catalog value), Wako first grade, Wako Pure Chemical Industries)
(No.10)
EO adduct of ethylene glycol (average added mole number of EO = 5000, polyethylene oxide, Mw200000 (catalog value), manufactured by Aldrich)
(No.11)
EO adduct of ethylene glycol (EO average addition mole number = 7.5, polyethylene glycol, Mw300 (catalog value), Wako first grade, Wako Pure Chemical Industries, Ltd.)
(No.12)
EO adducts of ethylene glycol (average added moles of EO = 12500, polyethylene glycol, Mw 300000 to 500,000 (catalog value), 400000 (median value), Wako first grade, manufactured by Wako Pure Chemical Industries)

Moreover, the detail of the water-soluble polymer compound used in Comparative Examples 15-17 as a comparison object of a polyhydric alcohol alkyloxide adduct (component B) is as follows.
(No.13)
18 crown 6 ether (manufactured by Tokyo Chemical Industry Co., Ltd., reagent)
(No.14)
Block type polyether "Pluronic F-68" (BASF, number average molecular weight 9600 (catalog value), polyoxypropylene part number average molecular weight 1920 (catalog value), polyoxyethylene part ratio 80% (catalog value) )
(No.15)
Diamine compound to which EG + block type polyether is bonded. A mixture of the compound of 8 and the compound (see formula below) of formula (7) in Patent Document 6 (see formula below), mass ratio 1: 1

<Measurement of weight average molecular weight of water-soluble polymer compound and polyhydric alcohol alkylene oxide adduct>
The weight average molecular weight of the water-soluble polymer compound (No. 1 to 10) and the polyhydric alcohol alkylene oxide adduct (No. 1 to 12) was determined by applying the gel permeation chromatography (GPC) method under the following measurement conditions. It calculated based on the peak in the chromatogram obtained.
<Measurement condition>
Equipment: HLC-8320 GPC (Tosoh Corporation, detector integrated type)
Column: GMPWXL + GMPWXL (anion)
Eluent: 0.2M phosphate buffer / CH3CN = 9/1
Flow rate: 0.5ml / min
Column temperature: 40 ° C
Detector: RI Detector Reference material: Polyethylene glycol

<Measurement of 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.

<Measurement of 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).

(1) Preparation of polishing liquid composition Water-soluble polymer compound, polyhydric alcohol alkylene oxide adduct, mixture of 29% ammonia water (Kanto Chemical Co., Inc.) and ultrapure water and silica particles (colloidal silica, average primary particles) The polishing liquid compositions of Examples 1 to 39 and Comparative Examples 1 to 17 (pH 10.6 ± 0.2 (25 ° C)). The content of the silica particles, the content of the water-soluble polymer compound, the polyhydric alcohol alkylene oxide adduct, and the content of ammonia in each polishing composition are 40 times the values shown in Table 1 and Table 2, respectively. It added so that it might become concentration, and the 40 times concentrated liquid of polishing liquid composition was obtained. The balance is ultra high purity water. In addition, the amount of silica particles, water-soluble polymer compound, polyhydric alcohol alkylene oxide adduct or comparison object thereof, and ammonia shown in Tables 1 and 2 are values after dilution of the concentrate with ultrapure water. (Dilution factor: 40 times). The pH of the diluted polishing composition is 10.3 ± 0.2 (25 ° C.).

  A 40-fold concentrated liquid of the polishing composition obtained as described above was diluted 40-fold so as to have the concentration shown in Table 1 or Table 2, and a silicon wafer (a silicon single-sided mirror wafer having a diameter of 200 mm, a conductive film) was polished under the following polishing conditions. (Type: P, crystal orientation: 100, resistivity 1 Ω · cm or more and less than 100 Ω · cm) was subjected to finish polishing. Prior to the final polishing, rough polishing was performed on the silicon wafer in advance using a commercially available abrasive composition under the following conditions. Surface defects on the surface of the silicon wafer substrate after profound polishing are LPD: 20 (0.15 μm or more), 10,000 or more (50 nm or more), and the surface roughness is Haze (DWO): 1.722, Haze ( DNN): 6.251.

(Rough polishing conditions)
Polishing machine: Single-sided 8-inch polishing machine TRCP-541 (manufactured by Technolize)
Polishing pad: Suede pad (FILWEL made by Asker hardness 66 thickness 1.10mm nap length 375um opening diameter 65um)
Silicon wafer polishing pressure: 150 g / cm ²
Surface plate rotation speed: 60 rpm
Polishing time: 7 minutes Supply rate of the abrasive composition: 200 g / cm ²
Abrasive composition temperature: 20 ° C
Carrier rotation speed: 60rpm

(2) Polishing method The polishing composition is filtered through a filter “Compact Cartridge Filter MCP-LX-C10S” (Advantech Co., Ltd.) immediately before polishing, and the following rough polishing is performed on the silicon wafer described below under the following polishing conditions. On the other hand, finish polishing was performed.

<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: 100 rpm
Polishing time: 10 minutes Supply rate of the abrasive composition: 200 g / cm ²
Abrasive composition temperature: 20 ° C
Carrier rotation speed: 100rpm

(3) Cleaning-drying method (after finish polishing)
After finish polishing, the silicon wafer was subjected to ozone cleaning and dilute hydrofluoric acid cleaning as follows. In ozone cleaning, pure water 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, pure water containing 0.5% ammonium hydrogen fluoride (special grade: Nacalai Tex Co., Ltd.) is jetted from the nozzle toward the center of the silicon wafer rotating at 600 rpm at a flow rate of 1 L / min for 6 seconds. did. 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 spin drying, the silicon wafer was rotated at 1500 rpm.

<Evaluation of surface defects (LPD) and surface roughness (haze) on the surface of silicon wafer>
The surface defect (LPD) and the surface roughness (haze) of the silicon wafer can be determined according to the following evaluation conditions.

  The surface roughness (haze) of the silicon wafer surface after cleaning is measured using a surface roughness measuring device “Surfscan SP1” (manufactured by KLA Tencor) in a dark field wide oblique incidence channel (DWO). The value and the value in the dark field narrow normal incidence channel (DNN) were used. As the evaluation of the surface roughness, both Haze (DWO) and Haze (DNN) were measured. Haze (DWO) is effective for measuring the surface roughness of a relatively short wavelength, and Haze (DNN) is It is suitable for measuring the surface roughness of relatively long wavelengths. Therefore, the surface roughness of the silicon wafer can be widely evaluated by measuring in two types of modes. Further, surface defects (LPD) were measured at the same time as the Haze measurement, and evaluated by measuring the number of particles having a maximum length of 50 nm or more on the silicon wafer surface. The results are shown in Table 1. The evaluation result of surface defects (LPD) indicates that the smaller the numerical value, the fewer surface defects. Moreover, it shows that the flatness of a surface is so high that the numerical value of Haze (DWO) and Haze (DNN) is small.

  As shown in Tables 1 and 2, the surface roughness (haze) and surface defects (LPD) of the polished silicon wafer were more than that of the polishing liquid compositions of Comparative Examples 1 to 17 in Example 1. Those using the polishing composition of ~ 39 were both smaller and better. In Comparative Example 9, the storage stability was poor, and aggregates were visually observed. Therefore, since it is clear that the evaluation results of the surface defect (LPD) and the surface roughness (haze: Haze) are bad, the evaluation of the surface roughness (haze: Haze) and the surface defect (LPD) was not performed.

  If the polishing composition of the present invention is used, surface defects (LPD) and surface roughness (haze) of the silicon wafer can be reduced. Therefore, the polishing liquid composition of the present invention is useful as a polishing liquid composition used in various semiconductor substrate manufacturing processes, and in particular, a polishing liquid composition for final polishing of a silicon wafer in a bare wafer manufacturing process. Useful as a product.

Claims (8)

Silica particles;
A nitrogen-containing basic compound and a water-soluble polymer compound containing 75% by mass or more of a structural unit represented by the following general formula (1) and having a weight average molecular weight of 150,000 to 1,500,000,
A polyhydric alcohol alkylene oxide adduct having a weight average molecular weight of 500 to 250,000,
An aqueous medium,
The polyhydric alcohol alkylene oxide adduct contains at least one alkylene oxide group selected from the group consisting of an ethyleneoxy group and a propyleneoxy group.
Polishing liquid composition for silicon wafers.

However, in the general formula (1), R ¹ is a hydroxyalkyl group having 1 to 2 carbon atoms.   2. The polishing composition for a silicon wafer according to claim 1, wherein a content of the polyhydric alcohol alkylene oxide adduct in the polishing composition for a silicon wafer is 0.00001 mass% or more and 0.005 mass% or less. .   3. The polishing composition for a silicon wafer according to claim 1, wherein the content of the water-soluble polymer compound in the polishing composition for a silicon wafer is 0.001 to 0.05% by mass. .   The polyhydric alcohol alkylene oxide adduct is obtained by addition polymerization of an alkylene oxide to a polyhydric alcohol, and the polyhydric alcohol has three or more hydroxyl groups in one molecule. The polishing composition for silicon wafers according to any one of the items.   The polishing composition for a silicon wafer according to any one of claims 1 to 4, wherein an average primary particle diameter of the silica particles is 5 nm or more and 50 nm or less.   The manufacturing method of a semiconductor substrate including the process of grind | polishing a silicon wafer using the polishing liquid composition for silicon wafers in any one of Claim 1 to 5. In the polishing step, used for polishing of the silicon wafer was concentrated the silicon co N'weha polishing slurry composition was diluted, the method of manufacturing a semiconductor substrate according to claim 6. A method for polishing a silicon wafer, comprising a polishing step of polishing the silicon wafer using the polishing composition for a silicon wafer according to any one of claims 1 to 5.