JP2018074048A - Polishing liquid composition for silicon wafer - Google Patents

Abstract

A polishing composition for a silicon wafer that can reduce haze and LPD on the surface of a polished silicon wafer, a polishing method using the polishing composition for a silicon wafer, and a method for manufacturing a semiconductor substrate are provided.
The present invention includes silica particles A, a basic compound B, and at least one compound C selected from polyglycerin and polyglycerin derivatives having a degree of branching of 59.8 or more, and has a pH of 9 The present invention relates to a polishing composition for silicon wafers that is 12 or less.
[Selection figure] None

Description

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

  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 semiconductor devices, and the demand for reduction of surface defects (LPD: Light point defects) and surface roughness (haze) of silicon wafers (bare wafers) becomes more severe. It has become.

  In order to improve the quality of silicon wafers, polishing of silicon wafers is performed in multiple stages. In particular, finish polishing performed at the final stage of polishing is performed for the purpose of reducing haze and reducing surface defects such as particles, scratches, and pits.

  As a polishing liquid composition used for polishing silicon wafers, silica particles and nitrogen-containing basics are used for the purpose of improving storage stability, ensuring a polishing rate that ensures good productivity, and reducing LPD and haze. A silicon wafer polishing composition comprising a 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). Further, as a polishing composition used for finish polishing, for the purpose of coexistence of reduction of haze and LPD, silica particles, nitrogen-containing basic compound, hydroxyl group-derived oxygen atoms and polyoxyalkylene-derived oxygen atoms A polishing composition for silicon wafers containing polyglycerin or the like as a water-soluble polymer compound having a ratio of 0.8 to 10 is disclosed (Patent Document 2).

JP 2013-222863 A JP 2015-109423 A

  The demand for reducing the haze and LPD of silicon wafers is becoming stricter, and there is a demand for a polishing composition that can further reduce haze and LPD.

  Accordingly, the present invention provides a polishing composition for a silicon wafer that can reduce haze and LPD on the surface of a polished silicon wafer, a polishing method using the same, and a method for manufacturing a semiconductor substrate.

  The present invention includes silica particles A, basic compound B, and at least one compound C selected from polyglycerin and polyglycerin derivatives having a branching degree of 59.8 or more, and has a pH of 9 or more and 12 or less. The present invention relates to a certain silicon wafer polishing composition.

  The present invention relates to a polishing method including a step of polishing a silicon wafer to be polished using the polishing composition for a silicon wafer of the present invention.

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

  According to the present invention, there are provided a polishing composition for a silicon wafer, a polishing method using the polishing composition for a silicon wafer, and a method for manufacturing a semiconductor substrate, which can reduce haze and LPD of the polished silicon wafer surface. Can be provided.

  In the present invention, the polishing composition for silica wafers containing silica particles and a basic compound contains specific polyglycerin, so that both haze and LPD are formed on the surface of the silicon wafer polished with the polishing composition. Based on the knowledge that can be reduced.

  That is, the present invention includes silica particles (hereinafter also referred to as “component A”), a basic compound (hereinafter also referred to as “component B”), polyglycerin having a degree of branching of 59.8 or more, and a polyglycerin derivative. A polishing liquid composition for silicon wafers (hereinafter referred to as “the polishing liquid composition of the present invention”) comprising at least one selected compound C (hereinafter also referred to as “component C”) and having a pH of 9 or more and 12 or less. ").

The details of the effect expression mechanism of the present invention are not clear, but are presumed as follows.
The component C contained in the polishing liquid composition of the present invention is adsorbed to the silicon wafer to be polished while the adsorption to the silica particles A is suppressed. Thereby, it is suppressed that the silica particle A which causes deterioration of haze and LPD directly contacts the silicon wafer to be polished, and corrosion of the wafer surface by the basic compound B which causes deterioration of haze and LPD. It is thought to be suppressed. Furthermore, component C quickly adsorbs on the surface of the silicon wafer to be polished, and forms a hard film after adsorption, thereby improving the detachability of particles (silica particles and polishing debris) in the cleaning process of the polished silicon wafer, and It is thought that it contributes also to reduction of haze and LPD.
However, the present invention is not limited to these mechanisms.

[Silica particle A (component A)]
The polishing composition of the present invention contains silica particles A (component A) as an abrasive. Specific examples of component A include colloidal silica and fumed silica. Colloidal silica is preferred from the viewpoint of reducing haze and LPD.

  The usage form of component A is preferably a slurry from the viewpoint of operability. When component A 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 size of component A is preferably 10 nm or more, more preferably 15 nm or more, and further preferably 20 nm or more, from the viewpoint of ensuring the polishing rate, and the viewpoint of ensuring the polishing rate and reducing haze and LPD. Therefore, 40 nm or less is preferable, 35 nm or less is more preferable, and 30 nm or less is still more preferable.

  In particular, when colloidal silica is used as Component A, the average primary particle size of Component A is preferably 10 nm or more, more preferably 15 nm or more, and more preferably 20 nm or more from the viewpoints of ensuring the polishing rate and reducing haze and LPD. Further, from the same viewpoint, it is preferably 40 nm or less, more preferably 35 nm or less, and further preferably 30 nm or less.

In the present invention, the average primary particle size of component A is calculated using the specific surface area S (m ² / g) calculated by the 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 component A is preferably 3.0 or less, more preferably 2.5 or less, still more preferably 2.3 or less, and the same viewpoint from the viewpoints of ensuring the polishing rate and reducing haze and LPD. Therefore, 1.1 or more is preferable, 1.5 or more is more preferable, and 1.8 or more is more preferable. When component A is colloidal silica, the degree of association is preferably 3.0 or less, more preferably 2.5 or less, and even more preferably 2.3 or less, from the viewpoints of ensuring the polishing rate and reducing haze and LPD. Preferably, from the same viewpoint, 1.1 or more is preferable, 1.5 or more is more preferable, and 1.8 or more is more preferable.

In the present invention, the association degree of component A 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

  Examples of the method for adjusting the degree of association of component A include, for example, JP-A-6-254383, JP-A-11-214338, JP-A-11-60232, JP-A-2005-060217, JP-A-2005-060219. It is possible to adopt the method described in the Gazette.

  The shape of component A is preferably so-called spherical and / or so-called mayu.

The content of Component A contained in the polishing composition of the present invention is preferably 0.04% by mass or more, more preferably 0.09% by mass or more, in terms of SiO ₂ , from the viewpoint of securing the polishing rate, more preferably 0 .15% by mass or more is more preferable, and from the viewpoint of reduction of haze and LPD, 0.5% by mass or less is preferable, 0.4% by mass or less is more preferable, and 0.3% by mass or less is more preferable. The mass% or less is still more preferable.

[Basic Compound B (Component B)]
The polishing composition of the present invention contains a water-soluble basic compound B (component B) from the viewpoints of improving storage stability, ensuring a polishing rate, and reducing haze and LPD. From the same viewpoint, Component B is preferably water-soluble, that is, it is preferably a water-soluble basic compound. In the present invention, “water-soluble” means having a solubility of 0.5 g / 100 mL or more in water (20 ° C.), preferably having a solubility of 2 g / 100 mL or more. The “basic compound” means a compound which shows basicity when dissolved in water.

  Examples of Component B include at least one nitrogen-containing basic compound selected from amine compounds and ammonium compounds. 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, mono Ethanolamine, diethanolamine, triethanolamine, N-methylethanolamine, N-methyl-N, N-diethanolamine, N, N-dimethylethanolamine, N, N-diethylethanolamine, N, N-dibutylethanolamine N- (β-aminoethyl) ethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, ethylenediamine, hexamethylenediamine, Perazine hexahydrate, anhydrous piperazine, 1- (2-aminoethyl) piperazine, N- methylpiperazine, diethylenetriamine, and one or more combinations thereof selected from tetramethylammonium hydroxide. The nitrogen-containing basic compound that can be contained in the polishing composition according to the present invention is preferably ammonia from the viewpoints of reducing haze and LPD, improving storage stability, and ensuring a polishing rate.

  The content of Component B contained in the polishing composition of the present invention is preferably 0.001% by mass or more, from the viewpoint of reducing haze and LPD, improving storage stability, and ensuring a polishing rate, and is 0.005. % By mass or more is more preferable, 0.01% by mass or more is more preferable, and from the viewpoint of reducing the surface roughness, 0.1% by mass or less is preferable, 0.05% by mass or less is more preferable, and 0.025% by mass. % Or less is more preferable.

  The ratio A / B of the content of component A to the content of component B contained in the polishing liquid composition of the present invention is preferably 0.5 or more, and preferably 1.0 or more, from the viewpoint of reducing haze and LPD. More preferably, 5.0 or more is still more preferable, and from the same viewpoint, 100 or less is preferable, 50 or less is more preferable, and 30 or less is still more preferable.

[At least one compound C (component C) selected from polyglycerol and polyglycerol derivatives]
The polishing composition of the present invention is at least one selected from polyglycerin and polyglycerin derivatives having a degree of branching of 59.8 or more from the viewpoint of reducing haze and LPD, improving storage stability, and ensuring a polishing rate. Compound C (component C). As one embodiment of the polyglycerin derivative, for example, polyglycerin and a water-soluble polymer other than component C are polymer-reacted, polyglycerin cross-linked, functional group bonded to polyglycerin, etc. Is mentioned. Examples of the water-soluble polymer other than Component C include water-soluble polymers having a carboxy group or a hydroxyl group. As what bridge | crosslinked polyglycerol, what reacted polyglycerol and the bifunctional or more epoxy compound, and what condensed polyglycerol are mentioned. Examples of the functional group include a polyoxyalkylene group, a fatty acid ester group, and an ether group. Other embodiments of the polyglycerin derivative of component C include, for example, one or more selected from a polyglycerin condensate, a polyglycerin crosslinked product, a polyoxyalkylene polyglycerether, a polyglycerin fatty acid ester, and a polyglycerin alkyl ether. Can be mentioned.

Examples of the method for producing polyglycerin include a method of dehydrating and condensing glycerin, a method of polymerizing glycidol, glycerin sulfonate, epichlorohydrin, and the like. Is preferred. The polyglycerin derivative can be produced by changing the compound for addition polymerization of glycidol, or by polyglycerin condensation or crosslinking reaction. Examples of the compound for addition polymerization of glycidol include glycerin, polyhydric alcohols described in paragraph [0035] of JP-A-2015-44955, and polyoxyalkylene compounds.
For the polymerization, for example, an activated carbon catalyst or an acid catalyst can be used, and an acid catalyst is preferable from the viewpoint of the degree of polymerization. Examples of the acid catalyst include Lewis acids such as BF3 complex, Bronsted acid, and heteropolyacid. From the viewpoint of safety, it is preferable to use Bronsted acid or phosphoric acid acid catalyst. . Examples of the Bronsted acid include C1-C4 carboxylic acids such as formic acid and acetic acid. Phosphoric acid catalysts include phosphoric acid, phosphoric anhydride, polyphosphoric acid, orthophosphoric acid, metaphosphoric acid, pyrophosphoric acid, triphosphoric acid, tetraphosphoric acid, etc .; methyl acid phosphate, ethyl acid phosphate, isopropyl acid phosphate Acidic phosphate esters such as butyl acid phosphate, 2-ethylhexyl acid phosphate, and the like. These may be used alone or in combination of two or more. The amount of catalyst and polymerization temperature that can be used for the polymerization can be appropriately set according to the degree of polymerization to be obtained. When an acid catalyst is used for the polymerization, the acid catalyst may be removed using an anion exchange resin. The amount of the acid catalyst used is preferably 100 ppm or less, more preferably 50 ppm or less, and still more preferably 30 ppm or less with respect to polyglycerin from the viewpoint of reducing the surface roughness.

The branching degree of Component C is 59.8 or more, preferably 60.0 or more, more preferably 60.5 or more, still more preferably 61.0 or more, from the viewpoint of reducing haze and LPD, and the like In view of the above, 100 or less is preferable, 80.0 or less is more preferable, and 70.0 or less is still more preferable. In the present invention, the “branch degree” means how many branch structures are present in the repeating unit of the glycerin residue in Component C. Here, it shows that there are many branching structures, so that the numerical value of a branching degree is large. The degree of branching of component C can be measured by ¹³ C-NMR. Specifically, it can be measured by the method described in the examples.

  The degree of polymerization of Component C is preferably 3,000 or less, more preferably 1,000 or less, still more preferably 200 or less, from the viewpoint of the stability of the polishing composition, and from the viewpoint of reducing haze and LPD. From a viewpoint, 15 or more are preferable, 25 or more are more preferable, and 30 or more are still more preferable. The degree of polymerization of Component C can be calculated from the hydroxyl value.

  The weight average molecular weight of Component C is preferably less than 250,000, more preferably 80,000 or less, still more preferably 20,000 or less, even more preferably 10,000 or less, and the same viewpoint from the viewpoint of haze and LPD reduction. Therefore, 1,000 or more is preferable, and 2,000 or more is more preferable. The weight average molecular weight of component C is measured by the method described in the following examples.

  The content of Component C contained in the polishing composition of the present invention is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, and 0.02% by mass from the viewpoint of haze and LPD reduction. The above is more preferable, and from the same viewpoint, it is preferably 1% by mass or less, more preferably 0.5% by mass or less, and further preferably 0.1% by mass or less.

  The ratio A / C of the content of component A to the content of component C contained in the polishing liquid composition of the present invention is preferably 0.1 or more, more preferably 0.5 or more, from the viewpoint of reducing haze and LPD. Preferably, 1.0 or more is more preferable, and from the same viewpoint, 100 or less is preferable, 50 or less is more preferable, and 30 or less is more preferable.

  The amount of component C adsorbed to component A in the polishing composition of the present invention is preferably 3% by mass or less, more preferably 2% by mass or less, and still more preferably 1% by mass or less from the viewpoint of haze and LPD reduction. The amount is more preferably less than 1% by mass, and more preferably 0% by mass or more. In the present invention, the adsorption amount can be calculated by the TOC method. Specifically, it can be calculated by the method described in the examples.

[Aqueous medium (component D)]
The polishing composition of the present invention may contain an aqueous medium (hereinafter also referred to as “component D”). Examples of the component D include water such as ion-exchanged water and ultrapure water, or a mixed medium of water and a solvent. The solvent is a solvent that can be mixed with water (for example, alcohol such as ethanol). Is preferred. As component D, from the viewpoint of haze reduction, ion-exchanged water or ultrapure water is more preferable, and ultrapure water is more preferable. When Component D is a mixed medium of water and a solvent, the ratio of water to the entire mixed medium is preferably 95% by mass or more, more preferably 98% by mass or more, and substantially 100% by mass from the viewpoint of economy. % Is more preferable.

  Content of the component D in the polishing liquid composition of this invention can be made into the remainder of the component E-the component E mentioned later, and other arbitrary components, for example.

  The pH of the polishing composition of the present invention at 25 ° C. is 9.0 or more, preferably 9.5 or more, more preferably 10.0 or more, and the same viewpoint from the viewpoint of ensuring the polishing rate. To 12.0 or less, more preferably 11.5 or less, and even more preferably 11.0 or less. The pH can be adjusted by appropriately adding at least one selected from Component B and 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 the electrode of the pH meter is immersed in the polishing composition, and the value after 1 minute is taken. it can.

[Component E: Polyoxyalkylene compound]
The polishing liquid composition of the present invention may further contain a polyoxyalkylene compound (component E) other than component C. Component E can be adsorbed on the silicon wafer to be polished. Therefore, component E acts to suppress adhesion of particles to the wafer surface, which is considered to be caused by drying of the wafer surface, by imparting wettability to the wafer surface while suppressing corrosion of the wafer surface by component B. Yes. Further, in the cleaning process of the polished silicon wafer, the component E can weaken the interaction between the component A and the silicon wafer. Therefore, component E, in combination with component C, is believed to enhance the reduction of surface roughness and surface defects.

  Component E is an alkylene oxide adduct of a polyhydric alcohol, for example, a polyhydric alcohol derivative obtained by addition polymerization of an alkylene oxide such as ethylene oxide, propylene oxide, or butylene oxide to a polyhydric alcohol. Component E preferably contains at least one alkyleneoxy group selected from an ethyleneoxy group and a propyleneoxy group from the viewpoint of reducing haze and LPD. The alkyleneoxy group contained in Component E is preferably composed of EO from the viewpoint of reducing haze and LPD. When the component E contains both EO and PO, the arrangement of EO and PO may be block or random.

  The number of hydroxyl groups of the polyhydric alcohol used as the raw material for component E is preferably 2 or more from the viewpoint of increasing the adsorption strength of component E on the surface of the silicon wafer, from the viewpoint of reducing haze and LPD, and from the viewpoint of securing the polishing rate. The number is preferably 10 or less, more preferably 8 or less, still more preferably 6 or less, and still more preferably 4 or less.

  Specific examples of component E include one or more selected from alkylene glycol alkylene oxide adducts such as polyethylene glycol (PEG) and polypropylene glycol; glycerin alkylene oxide adducts; and pentaerythritol alkylene oxide adducts. A combination is mentioned, Among these, an ethylene glycol alkylene oxide adduct is preferable from a viewpoint of reduction of haze and LPD.

The weight average molecular weight of component E is preferably 500 or more, more preferably 700 or more, still more preferably 900 or more, from the viewpoint of increasing the adsorption amount of component E to the polished silicon wafer and reducing haze and LPD. And from the viewpoint of increasing the adsorption amount of the component E to the silica particles and reducing haze and LPD, 250,000 or less is preferable, 100,000 or less is more preferable, 20,000 or less is further preferable, and 10,000 or less is more. Further preferred is 6,000 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>
Apparatus: HLC-8320 GPC (manufactured by Tosoh Corporation, integrated detector)
Column: α-M + α-M (cation)
Eluent: 50 mmol / L LiBr, 1% by mass acetic acid, solvent: ethanol / water = 3/7
Flow rate: 0.6mL / min
Column temperature: 40 ° C
Detector: RI Detector Standard: Monodispersed polyethylene glycol with known molecular weight

  The content of Component E contained in the polishing composition of the present invention is preferably 0.00001 ppm by mass or more, more preferably 0.0001 ppm by mass or more, and 0.001 ppm by mass from the viewpoint of reducing haze and LPD. Is more preferable. And from the same viewpoint, 0.1 mass ppm or less is preferable, and 0.05 mass ppm or less is more preferable.

  The ratio of the content of component C to the content of component E contained in the polishing liquid composition of the present invention (C / E) is preferably 0.1 or more, more preferably 1 or more, from the viewpoint of reducing haze and LPD. Preferably, 2 or more is more preferable, and from the same viewpoint, 3,000 or less is preferable, 1000 or less is more preferable, 100 or less is more preferable, and 20 or less is still more preferable.

[Other optional ingredients]
The polishing composition of the present invention is a water-soluble polymer compound (component F) other than components C and E, a pH adjuster, an antiseptic, an alcohol, and a chelating agent as long as the effects of the present invention are not hindered. , Anionic surfactants, and at least one other optional component selected from nonionic surfactants other than components C, E, and F may be included. The other optional component is preferably contained in the polishing liquid composition as long as the effects of the present invention are not impaired. The content of the other optional component in the polishing liquid composition is 0% by mass or more. Preferably, more than 0% by mass is more preferable, 0.1% by mass or more is further preferable, 10% by mass or less is preferable, and 5% by mass or less is more preferable.

  Component F includes, for example, a polymer compound having a hydrophilic group from the viewpoint of reducing haze and LPD. 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.). The weight average molecular weight of Component E is preferably 10,000 or more, and more preferably 50,000 or more, from the viewpoints of ensuring a polishing rate and reducing surface roughness and surface defects. Examples of the monomer that is a supply source constituting Component E include monomers having one or more water-soluble groups selected from amide groups, hydroxyl groups, carboxyl groups, carboxylic acid ester groups, and sulfonic acid groups. Can be mentioned. Specific examples of component E include one or more selected from polyamide, poly (N-acylalkylenimine), cellulose derivatives, and polyvinyl alcohol. Examples of the polyamide include one or more selected from polyvinylpyrrolidone, polyacrylamide, polyoxazoline, polydimethylacrylamide, polydiethylacrylamide, polyisopropylacrylamide, and polyhydroxyethylacrylamide. As poly (N-acylalkylenimine), poly (N-acetylethyleneimine), poly (N-propionylethyleneimine), poly (N-caproylethyleneimine), poly (N-benzoylethyleneimine), poly ( N-nonadezoylethyleneimine), poly (N-acetylpropyleneimine), and poly (N-butionylethyleneimine). Examples of the cellulose derivative include one or more selected from carboxymethyl cellulose, hydroxyethyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, ethyl cellulose, hydroxyethyl ethyl cellulose, and carboxymethyl ethyl cellulose.

  Examples of the pH adjuster include acidic compounds. Examples of the acidic compound include one or more selected from inorganic acids such as sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid; organic acids such as acetic acid, oxalic acid, succinic acid, glycolic acid, malic acid, citric acid, and benzoic acid. It is done.

  Examples of preservatives include benzalkonium chloride, benzethonium chloride, 1,2-benzisothiazolin-3-one, (5-chloro-) 2-methyl-4-isothiazolin-3-one, hydrogen peroxide, and the following 1 or more types chosen from chlorite are mentioned.

  Examples of alcohols include one or more selected from methanol, ethanol, propanol, butanol, isopropyl alcohol, 2-methyl-2-propanool, ethylene glycol, propylene glycol, polyethylene glycol, and glycerin.

  Chelating agents include ethylenediaminetetraacetic acid, ethylenediaminetetraacetic acid sodium, nitrilotriacetic acid, nitrilotriacetic acid sodium, nitrilotriacetic acid ammonium, hydroxyethylethylenediaminetriacetic acid, hydroxyethylethylenediamine sodium triacetate, triethylenetetramine hexaacetic acid, and triethylene 1 or more types chosen from sodium tetramine hexaacetate are mentioned.

  Examples of the anionic surfactant include fatty acid soaps, carboxylates such as alkyl ether carboxylates; sulfonates such as alkylbenzene sulfonates and alkylnaphthalene sulfonates; higher alcohol sulfates, alkyl ether sulfates 1 type or more chosen from sulfate ester salts, such as; phosphate ester salts, such as alkyl phosphate ester.

  Nonionic surfactants include, for example, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbit fatty acid ester, polyoxyethylene glycerin fatty acid ester, polyoxyethylene fatty acid ester, polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, One or more types selected from polyethylene glycol types such as polyoxyalkylene (hardened) castor oil; polyhydric alcohol types such as sucrose fatty acid esters and alkylglycosides; and fatty acid alkanolamides.

  Content of each component in the polishing liquid composition demonstrated above is content at the time of use of polishing liquid composition. The polishing composition of the present invention may be stored and supplied in a concentrated state as long as its storage stability is not impaired. In this case, it is preferable in that the production and transportation costs can be further reduced. The concentrated liquid of the polishing liquid composition of the present invention may be used by appropriately diluting with the above-mentioned aqueous medium as necessary at the time of use.

  Next, an example of a method for preparing a concentrated liquid of the polishing liquid composition will be described.

  The concentrated liquid of the polishing composition can be prepared, for example, by mixing Component A, Component B, and Component C with the above-described Component D, Component E, and other optional components as necessary.

  The dispersion of component A in the aqueous medium can be performed using, for example, a stirrer such as a homomixer, a homogenizer, an ultrasonic disperser, a wet ball mill, or a bead mill. When the coarse particles generated by the aggregation of the component A are contained in the aqueous medium, it is preferable to remove the coarse particles by centrifugation or filtration using a filter. The dispersion of component A in the aqueous medium is preferably carried out in the presence of component C.

[Manufacturing method and polishing method of semiconductor substrate]
The polishing liquid composition of the present invention can be used, for example, in a polishing method including 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. Examples of the silicon wafer to be polished which is a polishing target of the polishing composition of the present invention include a single crystal 100-plane silicon wafer, a 111-plane silicon wafer, a 110-plane silicon wafer, and the like, from the viewpoint of reducing haze and LPD. A single crystal 100-plane silicon wafer is preferred. The resistivity of the silicon wafer is preferably 0.0001 Ω · cm or more, more preferably 0.001 Ω · cm or more, still more preferably 0.01 Ω · cm or more, and still more preferably, from the viewpoint of reducing haze and LPD. It is 0.1 Ω · cm or more, preferably 100 Ω · cm or less, more preferably 50 Ω · cm or less, and further preferably 20 Ω · cm or less.

  The polishing process for polishing the silicon wafer to be polished includes, for example, a lapping (rough polishing) process for planarizing a single crystal silicon wafer obtained by slicing a single crystal silicon ingot into a thin disk shape, and a lapping single crystal After the etched silicon wafer is etched, a final polishing process for mirror-finishing the surface of the single crystal silicon wafer can be included. The polishing composition of the present invention is more preferably used in the finish polishing step from the viewpoint of reducing the surface roughness.

  Semiconductor substrate manufacturing method of the present invention (hereinafter also referred to as “the manufacturing method of the present invention”) and polishing method of the present invention (hereinafter also referred to as “the polishing method of the present invention”). May include a dilution step of diluting the concentrated liquid of the polishing composition of the present invention before the polishing step of polishing the silicon wafer to be polished. For example, an aqueous medium can be used as the diluent. The dilution factor is not particularly limited as long as the concentration at the time of polishing after dilution can be secured, and is preferably 2 times or more, more preferably 10 times or more, and 30 times from the viewpoint of further reducing the production and transportation costs. The above is further preferable, 55 or more is more preferable, and from the viewpoint of storage stability, 160 or less is preferable, 120 or less is more preferable, 100 or less is more preferable, and 60 or less is more preferable.

  The concentrate of the polishing composition diluted in the dilution step is, for example, 1 to 20% by mass of component A and 0.1 to 5 of component B from the viewpoints of manufacturing and transportation cost reduction and storage stability improvement. It is preferable to contain 0.1 to 10% by mass of component C.

  From the viewpoint of reducing haze and LPD, the concentrate of the polishing composition diluted in the dilution step preferably has a nickel content of 100 ppb or less, more preferably 20 ppb or less, still more preferably 5 ppb or less, and less than 1 ppb. Further more preferably, it is preferably larger than 0 ppb from the viewpoint of cost reduction. From the same viewpoint, the content of iron, copper, and silver contained in the concentrated liquid of the polishing composition is preferably 100 ppb or less, more preferably 20 ppb or less, still more preferably 5 ppb or less, and more than 0 ppb. Is preferred.

  In the step of polishing the silicon wafer to be polished, for example, the silicon wafer to be polished can be sandwiched with a surface plate to which a polishing pad is attached, and the silicon wafer to be polished can be 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. 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.

  In the step of polishing the silicon wafer to be polished, for example, the silicon wafer to be polished is sandwiched by a surface plate to which a polishing pad is attached, and the silicon wafer to be polished is polished at a polishing liquid composition of 15 ° C. or higher and 40 ° C. or lower and a polishing pad surface temperature. Can be polished. The temperature of the polishing composition and the surface temperature of the polishing pad are preferably 15 ° C. or higher or 20 ° C. or higher from the viewpoint of haze and LPD reduction, and preferably 40 ° C. or lower or 30 ° C. or lower from the viewpoint of haze reduction.

  The production method of the present invention and the polishing method of the present invention can 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.

[Polishing liquid kit]
The present invention is a polishing liquid kit for producing the polishing liquid composition of the present invention, which includes a silica dispersion liquid in a container in which a dispersion liquid containing silica particles (component A) is contained in a container. The present invention relates to a kit (hereinafter sometimes abbreviated as “kit of the present invention”). According to the kit of the present invention, a polishing composition capable of reducing haze can be obtained.
One embodiment of the kit of the present invention includes, for example, a silica dispersion containing component A, component B and component D and an aqueous additive solution containing component C and component D in a state where they are not mixed with each other. A polishing liquid kit (two-component polishing liquid composition) mixed at the time of use can be mentioned. In another embodiment of the kit of the present invention, for example, a silica dispersion containing component A, component B and component D and an aqueous additive solution containing component B, component C and component D are not mixed with each other. And a polishing liquid kit (two-component polishing liquid composition) in which these are mixed at the time of use and diluted with an aqueous medium as necessary. Each of the silica dispersion and the aqueous additive solution may contain the above-described component E and other optional components as necessary.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, these are illustrations, Comprising: This invention is not restrict | limited to these Examples.

1. Preparation of Polishing Liquid Composition Examples 1 to 14 and Comparative Examples 1 to 14 were prepared by stirring and mixing component A, component B-containing aqueous solution, component C or non-component C, component E, and ultrapure water as necessary. A concentrated solution of the polishing composition of No. 2 was obtained. The content of each component in Table 1 is the value for the polishing composition obtained by diluting the concentrated solution 50 times, that is, the value of the content of each component when the polishing composition is used. The content of ultrapure water is the remainder excluding component A, component B, component C or non-component C, and component E. The pH at 25 ° C. of each polishing composition (when used) was 10.6 ± 0.1.

  As component A, in Examples 1-10, 13-14 and Comparative Examples 1-2, colloidal silica (average primary particle size 35 nm, average secondary particle size 70 nm, association degree 2.0), in Example 11, Colloidal silica (average primary particle diameter 24 nm, average secondary particle diameter 49 nm, association degree 2.0), colloidal silica (average primary particle diameter 16 nm, average secondary particle diameter 26 nm, association degree 1.6) in Example 12 Was used. As the component B-containing aqueous solution, 28% by mass aqueous ammonia (manufactured by Kishida Chemical Co., Ltd., reagent special grade) was used. As component E, D1 (polyethylene glycol molecular weight 1,000) was used in Example 13, and D2 (polyethylene glycol molecular weight 2,000) was used in Example 14.

As the component C, the following C1 to C7 were used in Examples 1 to 14, and the following C8 and C9 were used in Comparative Examples 1 and 2.
C1: Polyglycerol, manufactured by Daicel Corporation, degree of polymerization 20
C2: Polyglycerin, “XPW” manufactured by Daicel Corporation, polymerization degree 40
C3: Polyglycerin, manufactured by Daicel, polymerization degree 50
C4: Polyglycerin, manufactured by Daicel, polymerization degree 60
C5: Polyglycerin, manufactured by Daicel, polymerization degree 80
C6: Polyglycerin, manufactured by Daicel, polymerization degree 100
C7: Cross-linked polyglycerin synthesized as follows C8: Polyglycerin, “X” manufactured by Daicel, polymerization degree 40
C9: HEAA homopolymer synthesized as follows (pHEAA)

<C7: Synthesis of crosslinked polyglycerol>
90 mass% polyglycerin aqueous solution (“PGL 20PW”, manufactured by Daicel) 55.6 g, glycerol diglycidyl ether (ALDRICH reagent) 6.12 g, 85 mass% phosphoric acid (Kishida Chemical Reagent) 0.1 g, ion-exchanged water 14 0.0 g was mixed and a crosslinking reaction was performed at 120 ° C. for 4 hours to obtain a polymer solution. Next, the pH of the polymer solution was adjusted to 7 using 28% by mass aqueous ammonia (Kishida Chemical Reagent). The pH-adjusted polymer solution was dialyzed for 3 days (dialysis tube, manufactured by Cosmo Bio, fractionated molecular weight 3,500), then freeze-dried, and colorless powdered crosslinked polyglycerin (weight average molecular weight: 9,500) was obtained.
<C9: Synthesis of pHEAA>
150 g of hydroxyethyl acrylamide (1.30 mol, manufactured by Kojin) 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. Then, an aqueous polymerization initiator solution was prepared. After putting 1,180 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, the temperature in the separable flask is raised to 68 ° C. using an oil bath, and then the separable flask in which the monomer aqueous solution and the polymerization initiator aqueous solution prepared in advance are each stirred for 3.5 hours. It was dripped in. After completion of the dropping, the temperature and stirring of the reaction solution were maintained for 4 hours to obtain 1,500 g of a colorless and transparent 10% by mass polyhydroxyethylacrylamide (pHEAA, weight average molecular weight: 700,000) aqueous solution.

2. Measurement method of various parameters (1) Measurement of average primary particle diameter of component A The average primary particle diameter (nm) of component A is based on the specific surface area S (m ² / g) calculated by the BET (nitrogen adsorption) method. The following formula was used.
Average primary particle diameter (nm) = 2727 / S

The specific surface area of the component A was subjected to the following [pretreatment], then weighed about 0.1 g of a measurement sample into the measurement cell to 4 digits after the decimal point, and immediately under the measurement at 110 ° C. for 30 minutes immediately before the measurement of the specific surface area. After drying, the surface area was measured by a nitrogen adsorption method (BET method) using a specific surface area measurement device (Micromeritic automatic specific surface area measurement device “Flowsorb III2305”, manufactured by Shimadzu Corporation).
[Preprocessing]
(A) The slurry-like component A is adjusted to pH 2.5 ± 0.1 with an aqueous nitric acid solution.
(B) The slurry-like component A 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 (component A) was taken so that filter waste was not mixed and finely pulverized in a mortar to obtain a measurement sample.

(2) Average secondary particle diameter of component A The average secondary particle diameter (nm) of component A is obtained after adding the abrasive to ion-exchanged water so that the concentration of component A is 0.25% by mass. The obtained aqueous dispersion was placed in a Disposable Sizing Cuvette (polystyrene 10 mm cell) 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). did.

(3) Measurement of weight average molecular weight of components C1-9 The weight average molecular weight of components C1-9 is calculated based on the peak in the chromatogram obtained by applying the gel permeation chromatography (GPC) method under the following conditions. did.

<Measurement conditions: pHEAA (component C9)>
Apparatus: HLC-8320 GPC (manufactured by Tosoh Corporation, integrated detector)
Column: GMPWXL + GMPWXL (anion)
Eluent: 0.2M phosphate buffer / CH ₃ CN = 9/1
Flow rate: 0.5mL / min
Column temperature: 40 ° C
Detector: Shodex RI SE-61 Differential refractive index detector Standard material: Monodispersed polyethylene glycol of known molecular weight

<Measurement conditions: polyglycerin (components C1 to C8)>
Apparatus: HLC-8320 GPC (manufactured by Tosoh Corporation, integrated detector)
Column: α-M + α-M (cation)
Eluent: 0.15 mol / L Na2SO4, 1% by mass acetic acid, solvent: water flow rate: 1.0 mL / min
Column temperature: 40 ° C
Detector: Shodex RI SE-61 Differential refractive index detector Standard material: Pullulan with known molecular weight

(4) Branching degree of component C1-8 The branching degree of component C1-8 was computed on the following conditions. Here, it shows that there are many branching structures, so that the numerical value of a branching degree is large.
Sample: 200 mg of components C1-8 dissolved in 0.6 mL of heavy water Device used: 400 MHz ¹³ C-NMR (“Agilent 400-MR DD2” manufactured by Agilent Technologies)
Measurement conditions: ¹³ C-NMR measurement, pulse interval time 10 seconds, tetramethylsilane as standard peak (σ: 0.0 ppm), measurement integration number: each peak range used for integration 5000 times, L1: 62.86-63. 93ppm
T: 64.96-65.28 ppm
L2: 74.62 to 74.81 ppm (the integrated value of this peak includes two carbons = 1/2 when calculated)
D: 79.53 to 83.05 ppm
The degree of branching is calculated from the respective peak integrated values according to the following formula.
Branching degree (DB) = 2D / (2D + L1 + L2 / 2) × 100

(5) Adsorption amount of component C1-9 to component A The concentrated solution of each polishing composition is ion-exchanged water so that component A, component B, component C or non-component C has the content shown in Table 1. After the addition, let stand for 15 minutes. Then, centrifugation (25000 rpm, 1 hour) is performed, the sediment containing a silica and a supernatant liquid are isolate | separated, and the TOC value of a supernatant liquid is measured. Separately, a calibration curve was created from the TOC values of aqueous solutions of components C1 to 9 at each concentration, and the adsorption rate of components C1 to 9 adsorbed on component A was calculated from the calibration curve and the TOC value of the supernatant.

3. Polishing method About the polishing liquid composition (pH 10.6 ± 0.1 (25 ° C.)) obtained by diluting the concentrated liquid of the polishing liquid composition with ion-exchanged water 50 times, a filter (compact cartridge) was used immediately before polishing. Filtration is performed with a filter “MCP-LX-C10S” (manufactured by Advantech), and the following silicon wafer (silicon single-sided mirror wafer having a diameter of 200 mm, conductivity type: P, crystal orientation: 100, resistivity: under the following polishing conditions. Final polishing was performed on 0.1 Ω · cm to 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 haze of the silicon wafer subjected to the final polishing after finishing the rough polishing was 2 to 3 ppm. The haze is a value in a dark field wide oblique incidence channel (DWO) measured using “Surfscan SP1-DLS” 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 (manufactured by Toray Cortex, Asker hardness: 64, thickness: 1.37 mm, nap length: 450 um, opening diameter: 60 um)
Silicon wafer polishing pressure: 100 g / cm ²
Surface plate rotation speed: 60 rpm
Polishing time: 5 minutes Feed rate of the polishing composition: 150 g / cm ²
Polishing liquid composition temperature: 23 ° C.
Carrier rotation speed: 62rpm

4). Cleaning method After final 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 of ozone was sprayed from a nozzle toward the center of a silicon wafer rotating at 600 rpm and 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.) is sprayed from the nozzle for 6 seconds toward the center of a silicon wafer rotating at a flow rate of 1 L / min and 600 rpm. 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 1,500 rpm.

5. Evaluation of Haze and LPD of Silicon Wafer For evaluation of haze (ppm) on the surface of a silicon wafer after cleaning, dark field wide obliqueness measured using “Surfscan SP1-DLS” (trade name) manufactured by KLA Tencor. The value at the incident channel (DWO) was used. Further, LPD (pieces) was measured at the same time as 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. The evaluation results of haze and LPD are shown in Table 1. Haze and LPD measurements were performed on two silicon wafers, and the average values are shown in Table 1.

  As shown in Table 1, when the polishing liquid compositions of Examples 1 to 14 were used, the haze and LPD of the polished silicon wafer were compared to when the polishing liquid compositions of Comparative Examples 1 and 2 were used. Was reduced.

  By using the polishing composition of the present invention, haze and LPD on the polished silicon wafer surface 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 is particularly useful as a polishing liquid composition for finish polishing of silicon wafers.

Claims (6)

  Silicon wafer containing silica particles A, basic compound B, and at least one compound C selected from polyglycerin and polyglycerin derivatives having a branching degree of 59.8 or more, and having a pH of 9 or more and 12 or less Polishing liquid composition.   The polishing composition for a silicon wafer according to claim 1, wherein the polymerization degree of compound C is 15 or more.   3. The polishing composition for a silicon wafer according to claim 1, wherein the content of the compound C during use of the polishing composition is less than 0.3% by mass.   The polishing composition for a silicon wafer according to any one of claims 1 to 3, further comprising a polyoxyalkylene compound E other than the compound C.   A polishing method comprising a step of polishing a silicon wafer to be polished using the polishing composition for a silicon wafer according to any one of claims 1 to 4.   The manufacturing method of a semiconductor substrate including the process of grind | polishing a to-be-polished silicon wafer using the polishing liquid composition for silicon wafers in any one of Claim 1 to 4.