WO2015050260A2

WO2015050260A2 - Polishing agent composition, polishing agent composition for silicon wafer, and method for manufacturing silicon wafer product

Info

Publication number: WO2015050260A2
Application number: PCT/JP2014/076631
Authority: WO
Inventors: 竜一谷本; 古屋田　栄; 孝一福井
Original assignee: 株式会社Sumco; Ａｔシリカ株式会社
Priority date: 2013-10-04
Filing date: 2014-10-03
Publication date: 2015-04-09
Also published as: WO2015050260A3; TW201529670A; JP6373273B2; KR101785450B1; TWI553049B; KR20160013971A; JPWO2015050260A1

Abstract

Provided are: a polishing agent composition that contains silica particles, an alkali substance, a water-soluble synthetic polymer, and water, and that is characterized by the water-soluble synthetic polymer having structural unit (1), the structural unit (1) having an oxygen-containing group and a carbonyl group, the oxygen-containing group being an alcoholic hydroxyl group or a substituted or unsubstituted alkoxy group, and the carbonyl group being a keto group or forming part of an ester bond or an amide bond; a polishing agent composition for silicon wafers that uses said polishing agent composition; and a method for manufacturing a silicon wafer product.

Description

Abrasive composition, abrasive composition for silicon wafer, and method for producing silicon wafer product

The present invention relates to an abrasive composition, an abrasive composition for silicon wafers, and a method for producing a silicon wafer product.

As an abrasive composition used for polishing a silicon wafer or the like, a slurry containing silica particles, an alkaline substance, a water-soluble polymer, water, and, if necessary, an additive is used.

As a water-soluble polymer used as a polishing aid in the above-mentioned abrasive composition, a material solubilized cellulose, for example, hydroxyethyl cellulose (HEC), carboxymethyl cellulose (CMC), hydroxypropyl cellulose (HPC), etc. has been reported. (Patent Document 1, Patent Document 2).

Examples of water-soluble polymers other than the above substances include water-soluble synthetic polymers. Examples of water-soluble synthetic polymers include polyethylene oxide, polyacrylamide, polyacrylic acid (Patent Document 2); polyvinylpyrrolidone, poly N-vinylformamide (Patent Document 3); block copolymer of ethylene oxide and propylene oxide (Patent Document) 4, 5); poly (N-acylalkylenimine) (Patent Document 6); or polyvinyl alcohol and a modified product thereof (Patent Document 7) used alone or mixed with other substances as a polishing aid It is reported to be possible.

U.S. Pat. No. 3,715,842 Japanese Patent Laid-Open No. 02-158684 JP 2008-53415 A Japanese Patent Laid-Open No. 10-245545 Japanese Patent Laying-Open No. 2005-85858 JP 2010-099757 A JP 2012-015462 A

However, in the water-soluble polymer in which cellulose is solubilized, insoluble components (free fibers) that are not partly reacted during the solubilization treatment inevitably remain. When the remaining insoluble component is mixed in the polishing composition, there is a problem that surface defects are likely to occur on the polished silicon wafer surface. In addition, since water-soluble polymers solubilized with cellulose are produced using natural pulp as raw materials, the performance (solubility, etc.) varies greatly depending on the raw material lot, and the surface quality of polished silicon wafer products There is a problem that (surface defects) are not stable.

On the other hand, water-soluble synthetic polymers that have been used in the past have high purity and are less likely to cause problems due to insoluble components, but are less hydrophilic than water-soluble polymers solubilized with cellulose, such as silicon wafers. There is a problem that the polishing liquid is not sufficiently retained on the surface to be polished, and deposits are likely to remain on the polished surface of the wafer that has been cleaned after polishing. Therefore, the development of water-soluble synthetic polymers with performance equal to or better than cellulose-solubilized water-soluble polymers has been developed so that products of higher quality after polishing (silicon wafer products, etc.) can be manufactured more stably. It was desired.

The object of the present invention is to stabilize the surface quality of a polishing target such as a silicon wafer after polishing by using a water-soluble synthetic polymer, and to improve the wettability of the surface of the polishing target, Abrasive composition capable of reducing the number of particles remaining on the polished surface after cleaning and LPD (Light Point Defect), an abrasive composition for silicon wafers, and a silicon wafer product using these abrasive compositions It is in providing the manufacturing method of. LPD is a defect observed as a bright spot when a wafer surface is scanned by laser irradiation of a light scattering particle counter.

That is, the present invention is a polishing composition comprising silica particles, an alkaline substance, a water-soluble synthetic polymer, and water, wherein the water-soluble synthetic polymer has the structural unit (1), and the structural unit (1 ) Has an oxygen-containing group and a carbonyl group, and the oxygen-containing group is an alcoholic hydroxyl group or a substituted or unsubstituted alkoxy group, and the carbonyl group is a keto group or a carbonyl group that forms part of an ester bond. Or a carbonyl group forming a part of an amide bond (Aspect 1).

Furthermore, the present invention provides an abrasive composition comprising silica particles, an alkaline substance, a water-soluble synthetic polymer, and water, wherein the water-soluble synthetic polymer is added to the water-soluble synthetic polymer of the above aspect 1 with an epoxy compound. It is an abrasive | polishing agent composition which is a reaction material obtained by making this react (aspect 2).

Further, the present invention is an abrasive composition for a silicon wafer comprising the abrasive composition of the above aspect 1 or aspect 2 (aspect 3).

Further, the present invention is a method for producing a silicon wafer product, comprising a step of polishing a silicon wafer using the abrasive composition of any one of the above aspects 1 to 3. (Aspect 4)

By using the water-soluble synthetic polymer of the present invention as a polishing aid, an abrasive composition having hydrophilicity equivalent to that using a conventional water-soluble polymer solubilized cellulose can be formed. Such a water-soluble synthetic polymer is less likely to cause quality variations than a water-soluble polymer solubilized with cellulose. Therefore, by using the water-soluble synthetic polymer of the present invention as a polishing aid, the wettability to the surface of the object to be polished is improved, and a silicon wafer having high quality surface characteristics (low residual particles and low LPD) is stabilized. It becomes possible to provide a polishing composition for a silicon wafer that can be supplied and a method for producing a silicon wafer product using the same.

It is a schematic diagram which shows a single-side polishing apparatus.

The abrasive composition according to the embodiment of the present invention will be described.
The abrasive composition according to the embodiment of the present invention includes silica particles (i), an alkaline substance (ii), a water-soluble synthetic polymer (iii), and water (iv). The abrasive composition according to this embodiment may further contain an additive (v).

In the present specification, “silica particles (i)” is a general term for particles represented by the composition formula SiO ₂ and particles obtained by surface-treating the particles. Examples of the silica particles (i) include colloidal silica, fumed silica, and precipitated silica, and surface-modified silica obtained by modifying these surfaces with boric acid treatment or aluminate treatment. Among these, colloidal silica and its surface-modified silica are more preferable from the viewpoint of improving the surface characteristics of the silicon wafer. The average particle diameter of the silica particles (i) can be measured by a BET method, a dynamic light scattering method, or the like.

The particle size of the silica particles (i) is not limited. The particle size of the silica particles (i) can be selected depending on the properties required for the polished product. For example, when improvement in surface characteristics after polishing is required, the primary particle size (which can be measured by the BET method) is 10 to 40 nm, or 10 to 20 nm, and the secondary particle size (dynamic light Can be measured by the scattering method.) Can be 20 to 80 nm, or 20 to 40 nm.

The method for producing the silica particles (i) is not limited. As a synthesis method of silica particles (i), a hydrothermal synthesis method from water glass, a sol-gel method from alkoxysilane or its condensate, a gas phase synthesis method from silicon chloride, and the like are known. When the object to be polished is a silicon wafer, silica particles produced by a sol-gel method from alkoxysilane or its condensate from the viewpoint of preventing the silicon wafer from being contaminated by impurities such as alkali metals and alkaline earth metals (I) is preferred.

The shape of the silica particles (i) is not particularly limited. Specific examples of the shape of the silica particles (i) include a true sphere type, a saddle type / new type, or a type having fine protrusions. The soot-type and new-type silica particles are silica particles having a ratio of secondary particle size / primary particle size of 1.5 to 2.5. Among the soot-type silica particles, silica particles prepared by a method including a step of hydrolyzing an alkoxysilane condensate may be particularly referred to as a new soot-type silica particle (Japanese Patent No. 4,712,556). In this specification, unless otherwise specified, such as “saddle type (not including a new soot type)”, the soot type includes a new soot type. From the viewpoint of improving both the polishing rate and the surface accuracy, it is preferable to use a saddle type or a new type.

The content of silica particles (i) is not limited. The content of the silica particles (i) is preferably 0.05 wt% or more and 0.5 wt% or less in the abrasive composition (slurry) used during polishing.

The alkaline substance (ii) can generate hydroxide ions in water that can chemically polish an object to be polished such as a silicon wafer. Furthermore, it has the effect | action which assists dispersion | distribution of a silica particle (i). From the viewpoint of obtaining such an action more stably, the alkaline substance (ii) is preferably dissolved in the composition.
Examples of the alkaline substance (ii) include ammonia, organic amine compounds, tetramethylammonium hydroxide, sodium hydroxide, and potassium hydroxide. Examples of organic amine compounds include methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, ethanolamine, diisopropylethylamine, ethylenediamine, diethylenetriamine, triethylenetetramine, tris (2-aminoethyl) amine, N, N, N ', N'-tetramethylethylenediamine, hexamethylenediamine, 1,4,7-triazacyclononane, 1,4,7-trimethyl-1,4,7-triazacyclononane, 1,4-diazabicyclo Examples include octane, piperazine, and piperidine. Alkaline substance (ii) may be comprised from 1 type of said substance, and may be comprised from 2 or more types.

Among the alkaline substances (ii), ammonia, organic amine compounds, and tetramethylammonium hydroxide are preferable from the viewpoint of not containing alkali metal ions, and ammonia is particularly preferable from the viewpoint of having an appropriate pKa.

The concentration of the alkaline substance (ii) depends on the contents of pKa and silica (i) of the alkaline substance (ii) used. The concentration of the alkaline substance (ii) is preferably a concentration of pH = 9.0 to 11.5 in a 40-fold concentrated solution of the abrasive composition (slurry) used during polishing, and pH = 10.0 to 11 A concentration of 0.0 is more preferable.

Water-soluble synthetic polymer (iii) contributes to polishing by adsorbing on the surface of a polishing target such as a silicon wafer to form a hydrophilic film.

In this specification, “water-soluble synthetic polymer” refers to a water-soluble polymer not derived from a natural product (cellulose or the like). However, it does not deny that the additive (v) includes a water-soluble polymer derived from a natural product solubilized with cellulose such as hydroxyethyl cellulose as long as the effect of the present invention is not impaired.

In the specific aspect 1, the abrasive composition according to this embodiment has the structural unit (1) in which the water-soluble synthetic polymer (iii) has an oxygen-containing group and a carbonyl group. Such an oxygen-containing group is an alcoholic hydroxyl group or a substituted or unsubstituted alkoxy group, and the carbonyl group is either a keto group, a carbonyl group that forms part of an ester bond, or a carbonyl group that forms part of an amide bond. It is.

Examples of the unsubstituted alkoxy (—OAk) group include alkoxy groups such as a methoxy group (—OCH ₃ ) and an ethoxy group (—OCH ₂ CH ₃ ). Here, “Ak” represents a linear or branched alkyl group. The number of carbon atoms of the alkyl group is not limited. For example, an alkyl group having 1 to 22, 1 to 12, 1 to 6, or 1 to 4 carbon atoms can be given.

The substituted alkoxy group (—OAk ′) is a group in which one or more carbon atoms of the alkoxy group are substituted. Examples of the substituent include a hydroxyl group, an alkoxy group (which may be substituted or unsubstituted), and halogen. Here, “Ak ′” represents a linear or branched and substituted alkyl group. The number of carbon atoms of the alkyl group is not limited. For example, an alkyl group having 1 to 22, 1 to 12, 1 to 6, or 1 to 4 carbon atoms can be given.

Examples of the substituted alkoxy group include hydroxyalkoxy groups such as a hydroxymethoxy group (—OCH ₂ OH) and a hydroxyethoxy group (—OCH ₂ CH ₂ OH). Examples of the substituted alkoxy group that is substituted include —OCH ₂ CH (OH) CH ₂ OH, —OCH (CH ₂ OH) CH ₂ OH, —OCH ₂ CH (CH ₃ ) OH, and —OCH (CH ₃ ) CH ₂ OH can be mentioned. One or more of the hydroxyl groups contained in the substituted alkoxy group may be further substituted with a substituted alkoxy group (specific examples include a hydroxyl group-substituted alkoxy group).

The monomer giving the structural unit (1) is not particularly limited. An example of such a monomer is a monomer (α) composed of a compound having an ethylenically unsaturated bond. Examples of the compound having an ethylenically unsaturated bond include (meth) acrylic acid, (meth) acrylic acid ester, (meth) acrylamide, N-substituted (meth) acrylamide, acrylonitrile, vinyl ester, vinylamide, allyl alcohol, allylamine. , Allyl esters, allylamides, and styrene.

The monomer (α) may have both an oxygen-containing group and a carbonyl group, or may be a compound having no oxygen-containing group, no carbonyl group, or none of these functional groups. . For the monomer (α) that does not have an oxygen-containing group, does not have a carbonyl group, or does not have any of these functional groups, a necessary functional group can be introduced after polymerization.

The monomer (α) is a reaction product obtained by reacting a compound having an ethylenically unsaturated bond and a hydroxyl group with a cyclic ether compound, and may have a substituted alkoxy group. In the present specification, the “cyclic ether compound” means a compound having a cyclic ether structure such as an epoxy group or an oxetane ring, which can open and react with the hydroxyl group of the above compound. A typical example of the cyclic ether compound is an epoxy compound which is a compound having an epoxy group. The epoxy group of the epoxy compound may be substituted. As such an epoxy compound, for example, ethylene oxide, propylene oxide, and glycidol can be mentioned as preferable ones.

The structural unit (1) may include at least one type of units (1A) to (1F) represented by the general formulas 1A to 1F.

In the above formulas 1A to 1F, X is CH ₂ , NH, or an oxygen atom, preferably NH or an oxygen atom, and more preferably NH. Each R ¹ is independently a hydrogen atom or a methyl group. Each R ² is independently a hydrogen atom, a hydroxyl group, or a substituted or unsubstituted alkoxy group. m1 to m10 are each independently an integer of 1 to 6, preferably an integer of 1 to 3. At least one of R ^{2 in} each unit is a substituent other than a hydrogen atom.

The m1 R ² present in the unit (1A) represented by the general formula 1A may be different substituents. At least one of m1 R ² is a substituent other than a hydrogen atom. Of m1 R ^{2 s} , at least one is preferably a hydroxyl group or a substituted alkoxy group, and more preferably two or more hydroxyl groups are present.
In the unit (1A) represented by the general formula 1A, m1 may be an integer of 3 to 6, R ¹ may be a methyl group, or X may be an oxygen atom.

(M2 + m3 + 1) R ² present in the unit (1B) represented by the general formula 1B may be different substituents. At least one of (m2 + m3 + 1) R ² is a substituent other than a hydrogen atom. Of (m2 + m3 + 1) R ² , at least one is preferably a hydroxyl group or a substituted alkoxy group, and more preferably two or more hydroxyl groups are present.

The (m4 + m5 + m6) R ² present in the unit (1C) represented by the general formula 1C may be different substituents. At least one of (m4 + m5 + m6) R ² is a substituent other than a hydrogen atom. Of (m4 + m5 + m6) R ² , at least one is preferably a hydroxyl group or a substituted alkoxy group, and more preferably two or more hydroxyl groups are present.

The (m7 + m8) R ² present in the unit (1D) represented by the general formula 1D may be a different substituent. At least one of (m7 + m8) R ² is a substituent other than a hydrogen atom. Of (m7 + m8) R ² , at least one is preferably a hydroxyl group or a substituted alkoxy group, and more preferably two or more hydroxyl groups are present.

M9 one of R ² that is present in the unit (1E) represented by the general formula 1E can each be different substituents. At least one of m9 R ² is a substituent other than a hydrogen atom. Of m9 R ² , at least one is preferably a hydroxyl group or a substituted alkoxy group, and more preferably two or more hydroxyl groups are present.

M10 one of R ² that is present in the unit (1F) represented by the general formula 1F may each be different substituents. At least one of m10 R ² is a substituent other than a hydrogen atom. Of m10 R ² , at least one is preferably a hydroxyl group or a substituted alkoxy group, and more preferably two or more hydroxyl groups are present.

From the viewpoint of enhancing the hydrophilicity of the water-soluble polymer (iii), it is preferable that each of the units (1A) to (1F) represented by the general formulas 1A to 1F has one or more hydroxyl groups, More preferably, it has a hydroxyl group.

The unit (1A) can be obtained, for example, by polymerizing the monomer (α). Examples of the monomer (α) used here include N- (hydroxymethyl) acrylamide, N- (2-hydroxyethyl) acrylamide, (2,3-dihydroxypropyl) acrylamide, and N- (hydroxymethyl) methacryl. Amides, N- (2-hydroxyethyl) methacrylamide, (2,3-dihydroxypropyl) methacrylamide, N- (hydroxymethyl) acrylate, N- (2-hydroxyethyl) acrylate, (2,3-dihydroxypropyl) Mention may be made of acrylates, N- (hydroxymethyl) methacrylates, N- (2-hydroxyethyl) methacrylates and (2,3-dihydroxypropyl) methacrylates.

The unit (1B) can be obtained, for example, by polymerizing the monomer (α). Examples of the monomer (α) used here include N- [bis (hydroxymethyl) methyl] acrylamide and (2-hydroxy-1-methylethyl) acrylamide.

The unit (1C) is obtained, for example, by polymerizing the monomer (α). Examples of the monomer (α) used here include N- [tris (hydroxymethyl) methyl] acrylamide.

The unit (1D) can be obtained, for example, by polymerizing the monomer (α). Examples of the monomer (α) used here include N, N-bis (hydroxymethyl) acrylamide and N, N-bis (hydroxyethyl) acrylamide.

The unit (1E) can be obtained, for example, by polymerizing the monomer (α). Examples of the monomer (α) used here include N-glycolyl vinylamine, N-lactyl vinylamine, N- (3-hydroxypropionyl) vinylamine, and pentahydroxyhexanoyl vinylamine. it can. Here, pentahydroxyhexanoyl vinylamine can be obtained, for example, by reacting vinylamine and gluconolactone.

The unit (1F) can be obtained, for example, by polymerizing the monomer (α). Examples of the monomer (α) used here include N-glycolylallylamine, N-lactylylamine, N- (3-hydroxypropionyl) allylamine, and pentahydroxyhexanoylallylamine. Here, pentahydroxyhexanoylallylamine can be obtained, for example, by reacting allylamine with gluconolactone.

In addition to the above, the units (1A) to (1F) can be synthesized by previously polymerizing an appropriate monomer to obtain a polymer, and then reacting this polymer with an appropriate compound.

Units (1A) to (1C) can also be obtained, for example, by reacting poly (meth) acrylic acid or poly (meth) acrylic acid ester with an alcohol or primary amine having an appropriate substituent.

The unit (1D) can also be obtained, for example, by reacting poly (meth) acrylic acid or poly (meth) acrylic acid ester with a secondary amine having an appropriate substituent.

Unit (1E) can also be obtained by reaction of polyvinyl alcohol or polyvinylamine with a carboxylic acid, carboxylic acid anhydride, carboxylic acid chloride, or lactone having an appropriate substituent.

The unit (1F) can also be obtained by reacting polyallyl alcohol or polyallylamine with a carboxylic acid, carboxylic acid anhydride, carboxylic acid chloride, or lactone having an appropriate substituent.

The water-soluble synthetic polymer (iii) may be a homopolymer or a copolymer. That is, when the structural unit (1) includes any one of the units (1A) to (1F), even if it is a homopolymer composed only of the same unit, it is composed of two or more different units. It may be a copolymer. In the case of a copolymer, it may contain two or more different units in any proportion. Furthermore, a structural unit other than the structural unit (1) may be included.

The water-soluble synthetic polymer (iii) may further have a structural unit (2) represented by the following general formula 2.

In the above formula 2, q is an integer of 1 to 6, preferably an integer of 1 to 3. X is CH ₂ , NH or an oxygen atom. Z ¹ , Z ² , Z ³ , and Z ⁴ are each independently a hydrogen atom or a methyl group. Y ⁻ is an anion. Examples of the anion include chlorine ion, bromine ion, iodine ion, nitrate ion, acetate ion, sulfate ion, phosphate ion, and hydroxide ion. For an anion having a valence greater than 1, such as sulfate ion (SO ₄ ²⁻ ), Y ⁻ contained in the structural unit (2) is equivalent to a unit price ion equivalent (1/2 in the case of sulfate ion). ).

The cationic group in the above formula 2 is a primary to quaternary amino group (ammonium group).

The method for obtaining the structural unit (2) is not limited. For example, the structural unit (2) can be obtained by polymerizing the following compounds as monomers. Examples of N-substituted acrylamides are N- (aminomethyl) acrylamide, N- (aminoethyl) acrylamide, N- (aminopropyl) acrylamide, N- (monomethylaminoethyl) acrylamide, N- (monomethylaminopropyl). Mention may be made of acrylamide, N- (dimethylaminoethyl) acrylamide, N- (dimethylaminopropyl) acrylamide, (acrylamidoethyl) trimethylammonium salt and (acrylamidopropyl) trimethylammonium salt. Alternatively, an appropriate compound (such as acrylic acid, methacrylic acid, acrylate, methacrylate, acrylamide, and methacrylamide, and derivatives thereof) is incorporated into a polymer by polymerization as a monomer, and then an appropriate compound To form a structural unit (2) by introducing a primary to quaternary amino group (ammonium group).

Since the structural unit (2) has a cationic group, when the object to be polished is a silicon wafer, the silicon wafer is negatively charged during polishing, so that the water-soluble polymer (iii) is adsorbed to the silicon wafer. It is expected that a protective film based on the water-soluble polymer (iii) is easily formed on the silicon wafer.

In the specific aspect 2 of the abrasive composition according to the present embodiment, the water-soluble synthetic polymer (iii) is different from the water-soluble synthetic polymer (iii) of the aspect 1 in that an epoxy compound or the like is used. It can be set as the reaction material obtained by making a cyclic ether compound react. When an epoxy compound is described as a specific example, ethylene oxide and glycidol are expected to increase the hydrophilicity, and propylene oxide is expected to increase the hydrophobicity and increase the adsorptivity to the wafer. In aspect 2, glycidol is particularly preferred.

There is no particular limitation on the terminal structure of the water-soluble synthetic polymer (iii) according to this embodiment. For the purpose of controlling the molecular weight, a known chain transfer agent may be used, which may constitute the terminal structure. From the viewpoint of introducing a hydroxyl group at the terminal, examples of preferred chain transfer agents include isopropyl alcohol, glycerin, and thioglycerin.

As the structural unit of the water-soluble synthetic polymer (iii) according to the present embodiment, known structural units other than the above can be included for the purpose of imparting various properties or adjusting hydrophilicity / hydrophobicity. For example, constitutional units having a structure obtained by polymerization of the following monomers can be mentioned (of course, further reaction may be carried out after polymerizing other monomers, and the same constitutional unit may be obtained as a result. .): Acrylamide, N-methylacrylamide, N-isopropylacrylamide, N-alkylacrylamide, N, N-dimethylacrylamide, N, N-dialkylacrylamide, acryloylmorpholine, N- (trimethoxysilylalkyl) acrylamide, acrylic acid, Methyl acrylate, ethyl acrylate, alkyl acrylate, trimethoxysilyl alkyl acrylate, vinyl ester (vinyl alcohol), vinyl amide (vinyl amine), N-alkanoyl vinyl amine, N-monoalkyl vinyl amine, N, N-dial Rubiniruamin, allylamine, N- alkanoyl allylamine, N- monoalkyl allylamine, N, N- dialkylallylamine, vinylpyrrolidone, oxazoline, alkyl oxazolines, vinyl imidazole, vinyl pyridine (vinylpyridine N- oxide), styrene, and hydroxystyrene.

The polymerization method of the monomer that gives the structural unit contained in the water-soluble polymer (iii) such as the structural unit (1) and the structural unit (2) is not limited. It can superpose | polymerize by a conventionally well-known method.

The molar fraction of the structural unit (1) with respect to the entire structural unit of the water-soluble synthetic polymer (iii) according to the present embodiment is not particularly limited. From the viewpoint of hydrophilicity, it is preferably 50 mol% or more, more preferably 70 mol% or more, and further preferably 80 mol% or more.

The molar fraction of the structural unit (2) with respect to the entire structural unit of the water-soluble synthetic polymer (iii) according to Embodiment 2 is not particularly limited. From the viewpoint of moderately suppressing the aggregation of silica, the molar fraction of the structural unit (2) is preferably less than 50 mol%, more preferably 0.01 mol% or more and 10 mol% or less. When it is desired to suppress the aggregation of silica more stably, the molar fraction of the structural unit (2) can be 0.01 mol% or more and 5 mol% or less. When the object to be polished is a silicon wafer, from the viewpoint of reducing the haze of the polished wafer, the molar fraction of the structural unit (2) can be 0.01 mol% or more and 2 mol% or less.

The molecular weight of the water-soluble synthetic polymer (iii) according to this embodiment is not limited. From the viewpoint of obtaining a protective film having an appropriate strength by adsorbing to the surface of a polishing target such as a silicon wafer, the weight average molecular weight (Mw) is preferably 1,000 or more. From the viewpoint of obtaining a stronger protective film, the weight average molecular weight (Mw) is more preferably 5,000 or more. In order to obtain a stronger protective film, the weight average molecular weight (Mw) is preferably 10,000 or more. On the other hand, if the weight average molecular weight (Mw) is too large, the aggregation of silica may be excessively promoted, or the protective film may be difficult to be removed by washing with water after polishing. Therefore, the molecular weight of the water-soluble synthetic polymer (iii) according to this embodiment is preferably 5,000,000 or less in terms of weight average molecular weight (Mw). Further, when the weight average molecular weight (Mw) is large, the protective film formed from the water-soluble synthetic polymer (iii) may have a structure having many gaps. From the viewpoint of more stably reducing the possibility that such a protective film is formed, 1,000,000 or less is preferable.

The concentration of the water-soluble synthetic polymer (iii) according to the present embodiment is preferably 10 ppm or more and 1000 ppm or less in the abrasive composition (slurry) used during polishing. In this, 20 ppm or more and 750 ppm or less are more preferable.

In the abrasive composition according to this embodiment, water (iv) has a function of dissolving or dispersing other components. In order to prevent the action inhibition of other components, it is preferable that the amount of impurities contained in water (iv) is small. Specifically, distilled water, ion exchange water, ultrapure water and the like are preferable. The content of water (iv) in the polishing composition is the remaining amount with respect to the concentration and content of other components in the polishing composition.

The abrasive composition according to this embodiment may further contain an additive (v). For example, for adjusting various properties of the slurry, capturing metal ions, assisting adsorption of the water-soluble synthetic polymer (iii) to the object to be polished (specifically, a silicon wafer is exemplified), or other purposes, Additives can be added. Specifically, for example, one or more additives can be added from alcohols, chelates, and nonionic surfactants. Examples of alcohols include methanol, ethanol, propyl alcohol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, glycerin, polyethylene glycol, and polypropylene glycol. Examples of chelates include ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), hydroxyethylenediaminetetraacetic acid, propanediaminetetraacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraminehexaacetic acid, and their ammonium, sodium, And metal salts such as potassium salts. Examples of nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkenyl ethers, polyoxyalkylene alkyl ethers, polyoxyalkylene alkenyl ethers, alkyl polyglycosides, and polyether-modified silicones.

The manufacturing method of the abrasive composition according to this embodiment is not limited. Conventionally known methods can be used. For example, the abrasive composition according to this embodiment can be obtained by mixing silica particles (i), an alkaline substance (ii), a water-soluble synthetic polymer (iii), and water (iv).

Specific aspect 3 of the abrasive composition according to the present embodiment relates to an abrasive composition for silicon wafers comprising the abrasive composition according to any one of aspects 1 and 2.
The abrasive composition for a silicon wafer can be obtained by mixing silica particles (i), an alkaline substance (ii), a water-soluble synthetic polymer (iii), and water (iv). The obtained abrasive composition for silicon wafers can be used, for example, for final polishing of silicon wafers in a semiconductor device manufacturing process.

Specific Aspect 4 of the abrasive composition according to the present embodiment includes the step of polishing a silicon wafer using the abrasive composition according to any one of Aspects 1 and 2 above. Regarding the method. In the present specification, the “silicon wafer product” means a product obtained by polishing a silicon wafer using the abrasive composition according to any one of the first and second aspects. Such a process can be introduced as a polishing process for a silicon wafer, and it is particularly preferable to introduce it as a final polishing process for a silicon wafer.

Abbreviations used in the present specification are as follows.
HEAA: N- (2-hydroxyethyl) acrylamide TMAPAA: (3-acrylamidopropyl) trimethylammonium chloride DHPMA: (2,3-dihydroxypropyl) methacrylate and bis (hydroxymethyl) methyl methacrylate mixture (about 75 mol%: about 25 mol) %)
THMMAA: N- [Tris (hydroxymethyl) methyl] acrylamide HPAA: N- (3-hydroxypropyl) acrylamide DHPAA: N- (2,3-dihydroxypropyl) acrylamide HEMAA: N- (2-hydroxyethyl) methacrylamide DHPMAA : N- (2,3-dihydroxypropyl) methacrylamide HEAA-GO _0.25 : N- (2-hydroxyethyl) acrylamide-glycidol adduct PAA: poly (acrylamide)
PHEOVE: Poly (hydroxyethyloxyethyl vinyl ether)
PVA: polyvinyl alcohol PVP: poly (vinyl pyrrolidone)
PPEI: Poly (N-propionylethyleneimine)

The embodiment described above is described for facilitating understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

Hereinafter, the present invention will be specifically described by way of examples. However, the present invention is not limited to the following examples.

Examples 1 to 8, Reference Example 1, and Comparative Examples 1 to 5
<Preparation of monomer>
DHPMA was synthesized from glycidyl methacrylate manufactured by Aldrich by the method described in the literature (Shaw et al., Polymer 47, 8247-8252, 2006). According to the literature, the product is a mixture of (2,3-dihydroxypropyl) methacrylate and bis (hydroxymethyl) methylmethacrylate (about 75 mol%: about 25 mol%). When the product was confirmed by GPC measurement, two peaks were observed at an area ratio of 75:25.

Other sources of monomers are as follows.
HEAA: Tokyo Kaseisha TMAPAA: Tokyo Kaseisha THMMAA: Aldrich AG AA: Tokyo Kaseisha

<Synthesis of water-soluble synthetic polymer>
The water-soluble synthetic polymers of Examples 1 to 8 and Comparative Example 1 were synthesized by the following method.
In an ammonium persulfate solution (ammonium persulfate 1.6 g (7.0 mmol), pure water 1000 g) maintained at 70 ° C. under a nitrogen stream, a monomer of 1.0 mol (in the case of a copolymer, the amount of all monomer substances) A solution consisting of 1.0 mol) and 960 g of pure water was added dropwise over about 2 hours. After completion of dropping, the mixture was further stirred at 70 ° C. for 1 hour, and then cooled to room temperature. Subsequently, in order to remove unreacted monomers, the reaction solution was dropped into 5 volumes of acetone. The produced precipitate was taken out by decantation, washed with 1 volume of acetone, and then vacuum dried.
Examples 2 and 3 are copolymers composed of HEAA and TMAPAA, Examples 5 and 6 are copolymers composed of HEAA and DHPMA, and Example 8 is a copolymer composed of HEAA and THMAA. The charge ratio (molar ratio) of each monomer is shown in Table 1.
HEC of Reference Example 1 was obtained from Daicel FineChem, and PEG was obtained from Wako Pure Chemical Industries.
The PVA of Comparative Example 2 was obtained from Wako Pure Chemical Industries, and the PHEOEVE of Comparative Example 3 was obtained from Maruzen Petrochemical Co., Ltd.
The PVP of Comparative Example 4 and the PPEI of Comparative Example 5 were obtained from Aldrich.

Example 9
<Synthesis of polyHPAA>
0.020 g of APS was added to a mixed liquid of 2.15 g of methyl acrylate (MA) and 8.58 g of methanol, and then polymerization was performed at 65 ° C. for 10 hours under nitrogen. Thereafter, the reaction solution was cooled to room temperature, and the generated precipitate was taken out by decantation to obtain a polymethyl acrylate solid (conversion rate 97%). 8.58 g of methanol was added again to the obtained polymethyl acrylate solid, heated at 65 ° C. for 10 minutes, cooled to room temperature, and the supernatant was removed to remove unreacted monomers.
To the obtained poly (methyl acrylate), 5.63 g of 3-aminopropanol and 0.082 g of 28% NaOMe methanol solution were added, and an amidation reaction was performed at 100 ° C. for 20 hours. After completion of the reaction, the reaction solution was added dropwise with 3.3 g of methanol and then dropped into 25 g of acetone. The produced solid was separated from the supernatant by decantation, further rinsed with 15 g of acetone, and vacuum dried at 40 ° C. for 1 hour. After drying, it was dissolved in 30 g of pure water, and then filtered through a 3 μm filter. After sampling about several g from the filtrate and quantifying the polymer concentration by a drying method, an appropriate amount of pure water was added to finally make a polyHPAA 5% aqueous solution (yield 80%).

Example 10
<Synthesis of polyDHPAA>
From the synthesis of polyHPAA, a 5% aqueous solution of polyDHPAA was obtained in the same manner except that 3-aminopropanol was replaced with 6.83 g of 3-amino-1,2-propanediol (yield 75%).

Example 11
<Preparation of monomer>
0.984 g of 28% NaOMe methanol solution was added dropwise to 10.0 g of ice-cooled methyl methacrylate (MMA). Next, the ice-cooling was removed, and 6.72 g of 2-aminoethanol was added dropwise over 30 minutes. At this time, care was taken that the liquid temperature of the reaction liquid did not exceed 30 ° C. Furthermore, after making it react at room temperature overnight, 25 g of pure water and 8.8 mL of cation exchange resin (organo Corporation 200CT H AG) were added, and the reaction liquid was neutralized. The cation exchange resin was removed by filtration through a 1 μm filter to obtain an aqueous HEMAA monomer solution. After sampling about several grams from the solution and quantifying the monomer concentration by a drying method, an appropriate amount of pure water was added to form a 20% HEMAA monomer aqueous solution (yield 68%).
<Synthesis of polyHEMAA>
After adding 0.10 g of 10% APS aqueous solution to the mixed solution of 8.40 g of HEMAA aqueous solution obtained above and 8.30 g of pure water, polymerization was performed at 65 ° C. for 10 hours under nitrogen. After completion of the polymerization, the reaction solution cooled to room temperature was dropped into 30 g of acetone to obtain a polyHEMAA solid. The obtained solid was further rinsed with 15 g of acetone and then vacuum-dried at 40 ° C. for 1 hour. The vacuum-dried solid was dissolved in 30 g of pure water and filtered through a 3 μm filter. After sampling about several grams from the solution and quantifying the polymer concentration by a drying method, an appropriate amount of pure water was added to finally make a 5% polyHEEMA aqueous solution (yield 74%).

Example 12
<Preparation of monomer>
A 10% DHPMAA monomer aqueous solution was obtained by the same method except that 2-aminoethanol was replaced with 10.00 g of 3-amino-1,2-propanediol from the monomer synthesis of polyHEMAA (yield 90%).
<Synthesis of polyDHPMAA>
From the polymer synthesis of polyHEMAA, a 5% polyDHPMAA aqueous solution was obtained in the same manner except that the HEMAA aqueous solution was replaced with 8.40 g of the DHPMAA aqueous solution (yield 77%).

Example 13
<Preparation of monomer (HEAA: GO = 1: 0.25 mol / mol)>
To a mixed liquid of 1.00 g of HEAA monomer heated to 70 ° C. and 0.0025 g of N, N′-tetramethylethylenediamine (TEMED), 0.16 g of glycidol was dropped over about 1 hour. After the completion of dropping, the temperature was maintained at 70 ° C. for 10 minutes, and then returned to room temperature.
<Synthesis of poly (HEAA-GO _0.25 )>
To the reaction solution, 21.9 g of pure water and 0.14 g of 10% APS aqueous solution were added, and polymerization was carried out at 65 ° C. for 10 hours under nitrogen. After completion of the polymerization, 3 μm filter filtration was performed. The obtained solution was regarded as a 5.0% solution of poly (HEAA-GO _0.25 ) and used for preparing various experimental solutions / slurries.

<Molecular weight and molecular weight distribution>
The number average molecular weight (Mn) and the weight average molecular weight (Mw) of the water-soluble synthetic polymers of Examples 1 to 13, Reference Example 1 and Comparative Examples 1 to 5 were measured by GPC measurement. The conditions of GPC measurement were as follows. The molecular weight values are shown in Table 1.
GPC device: SCL-10A manufactured by Shimadzu Corporation
Column: Tosoh Corporation TSKgel GMPW _XL (× 1) + TSKgel G2500PW _XL (× 1)
Eluent: 0.1 mol / kg NaCl, 20% methanol, remaining pure water flow rate: 0.6 mL / min
Detection method: RI + UV (254 nm)
Reference material: Polyethylene oxide

<Wetting test: water-soluble synthetic polymer>
A 1-inch silicon wafer was immersed in 1% hydrofluoric acid for 2 minutes to remove the oxide film on the surface. After confirming that the surface repels water sufficiently (0% wettability), each wafer was subjected to 4000 ppm aqueous solution of each water-soluble synthetic polymer of Examples 1 to 13, Reference Example 1 and Comparative Examples 1 to 5 (Reference Example 1 is HEC 3600 ppm). PEG400ppm) for 10 minutes. After 10 minutes, the wafer was taken out and lightly watered, and the wettability of the surface was confirmed. Here, the wettability is a percentage of the total wetted area on the wafer surface. The results are shown in Table 1.

<Preparation of abrasive composition (slurry)>
The abrasive composition was a silica particle slurry prepared by the method described in Japanese Patent No. 4712556 (particle size 17.8 nm by BET method; particle size D50 by dynamic light scattering method = 30.7 nm, SD = 10.0 nm) Ammonia water (manufactured by Kanto Chemical Co., Inc.), an aqueous solution of a water-soluble polymer, and ion-exchanged water were mixed to prepare.

<Polishing rate and wettability after polishing: abrasive composition>
Polishing was performed under the following conditions, and the polishing rate was determined from the change in weight of the wafer before and after polishing. Further, for the wafer immediately after polishing, the surface was lightly sprayed with pure water, and then the wettability of the surface was confirmed. The results are shown in Table 1.
Abrasive composition: silica 1125 ppm, ammonia 100 ppm, water-soluble synthetic polymer 100 ppm (Reference Example 1 is HEC 90 ppm, PEG 10 ppm)
Polishing machine: LGP-15S-I manufactured by Micro Engineering Co., Ltd.
Wafer: 4-inch silicon wafer (P type, resistivity 5-18 mΩ · cm, crystal plane direction <111>)
Surface pressure: 0.25 kgf / cm ²
Wafer rotation speed: 100 rpm
Pad: SURFIN SSWI manufactured by Fujimi
Pad rotation speed: 30 rpm
Polishing slurry supply rate: 100 mL / min Polishing time: 10 minutes

註: In the water-soluble polymer / molecular weight / Mn and Mw cell of Reference Example 1, the upper number indicates the molecular weight of HEC and the lower number indicates the molecular weight of PEG.
As is clear from Table 1, in all the results of Examples 1 to 13, it was confirmed that the wettability of the polished wafer surface was high.

<LPD evaluation>
Next, using the polishing liquid containing the various water-soluble polymers described above as the polishing liquid for final polishing in the manufacturing process of the silicon wafer for products, LPD (Light Point Defect) observed on the surface of the polished silicon wafer Density was evaluated.
Specifically, the following experiment was conducted.
A plurality of 300 mm diameter double-side polished silicon wafers were prepared as sample wafers for the final polishing test. Using a single-sided mirror polishing (CMP) apparatus (not shown), a single-side polishing process for removing 1 μm of the surface of each sample wafer was performed to remove processing damage on the surface of each sample wafer. Thereafter, as the final finish single-side polishing treatment, the surface of each sample wafer was finish-polished using a polishing liquid of a five-level polishing composition shown in Table 2. The final polishing treatment conditions were the same. Specifically, the single-sided mirror polishing shown in FIG. 1 was used and held by the suede polishing cloth 3 and the polishing head 4 attached on the polishing surface plate 2. The polishing liquid was supplied from the polishing liquid supply nozzle 1 at a rate of about 500 ml / min while rotating the sample wafer 5 with each other, and a finish single-side polishing process was performed under the conditions of polishing pressure: 125 g / cm ² and polishing time: 300 seconds. The preparation of the abrasive composition (slurry) was the same as in Examples 1 to 13 except for the water-soluble polymer used and the concentration of each component.
The water-soluble synthetic polymer of Example 14 is the same polyHEAA as in Example 1,
The water-soluble synthetic polymer of Example 15 is the same polyHEMAA as Example 11,
The water-soluble synthetic polymer of Example 16 is the same poly (HEAA-GO _0.25 ) as Example 13, the water-soluble synthetic polymer of Comparative Example 6 is the same PAA as Comparative Example 1, and the water-soluble synthetic polymer of Reference Example 2 is high. The molecule used was the same HEC + PEG as in Reference Example 1.
After the RCA cleaning of each finish polished sample wafer, an LPD density of 35 nm size or more observed on the surface of each sample wafer was measured using a surface defect inspection apparatus (KLA-Tencor: Surfscan SP-2). The LPD results shown in Table 2 are the average values of the measurement results of the six sample wafers subjected to finish polishing at each level, and are shown as relative values when the average value of Reference Example 1 is 100. is there.
As is apparent from Table 2, in Examples 14 to 16, the LPD density was a defect. On the other hand, in Comparative Example 6, the number of detection points was too large for all the sample wafers, and the data overflowed, making measurement impossible.

The abrasive composition of the present invention, the abrasive composition for silicon wafers, and the method for producing a silicon wafer product can be used to stably supply silicon wafers having high quality surface characteristics (low residual particles and low LPD). It is.

1: polishing liquid supply nozzle, 2: polishing surface plate, 3: polishing cloth, 4: polishing head, 5: sample wafer

Claims

A polishing composition comprising silica particles, an alkaline substance, a water-soluble synthetic polymer, and water,
The water-soluble synthetic polymer has a structural unit (1),
The structural unit (1) has an oxygen-containing group and a carbonyl group,
The oxygen-containing group is an alcoholic hydroxyl group or a substituted or unsubstituted alkoxy group,
The abrasive composition, wherein the carbonyl group is a keto group, a carbonyl group that forms part of an ester bond, or a carbonyl group that forms part of an amide bond.
The structural unit (1) is derived from the monomer (α),
The abrasive composition according to claim 1, wherein the monomer (α) is a reaction product obtained by reacting an epoxy compound with a compound having an ethylenically unsaturated bond and a hydroxyl group, and has a substituted alkoxy group. object.
The abrasive composition according to claim 1 or 2, wherein the structural unit (1) contains at least one unit of units (1A) to (1F) represented by the general formulas 1A to 1F. .

(In the above formulas 1A to 1F, X is CH 2 , NH, or an oxygen atom. R 1 is independently a hydrogen atom or a methyl group. R 2 is independently a hydrogen atom, a hydroxyl group, or a substituent. Or an unsubstituted alkoxy group, wherein m1 to m10 are each independently an integer of 1 to 6. At least one of R 2 in each unit is a substituent other than a hydrogen atom.
4. The abrasive composition according to claim 3, wherein each of the units (1A) to (1F) represented by the general formulas 1A to 1F has one or more hydroxyl groups.
The abrasive composition according to claim 3 or 4, wherein each of the units (1A) to (1F) represented by the general formulas 1A to 1F has two or more hydroxyl groups.
In the general formulas 1A, 1B, 1C, 1E, and 1F, X is NH or an oxygen atom, The abrasive composition according to any one of claims 3 to 5.
The abrasive composition according to any one of claims 1 to 6, wherein the molar fraction of the structural unit (1) with respect to the entire structural unit of the water-soluble synthetic polymer is 50 mol% or more.
The said water-soluble synthetic polymer is an abrasive | polishing agent composition as described in any one of Claim 1 to 7 which further has the structural unit (2) represented by following General formula 2.

(In Formula 2, q is an integer of 1 to 6. X is CH 2 , NH or an oxygen atom. Z 1 , Z 2 , Z 3 and Z 4 are each independently a hydrogen atom or a methyl group. Y − is an anion.)
The abrasive | polishing agent composition of Claim 8 whose molar fraction of the said structural unit (2) with respect to the whole structural unit of the said water-soluble synthetic polymer is less than 50 mol%.
An abrasive composition comprising silica particles, an alkaline substance, a water-soluble synthetic polymer, and water,
The said water-soluble synthetic polymer is an abrasive | polishing agent composition which is a reaction material obtained by making an epoxy compound react with the water-soluble synthetic polymer as described in any one of Claims 1-9.
The silica particle according to any one of claims 1 to 10, wherein the silica particles are prepared using alkoxysilane or a condensate thereof as a raw material, and have a primary particle diameter of 10 to 40 nm and a secondary particle diameter of 20 to 80 nm. Abrasive composition.
An abrasive composition for silicon wafers, comprising the abrasive composition according to any one of claims 1 to 11.
A method for producing a silicon wafer product, comprising a step of polishing a silicon wafer using the abrasive composition according to any one of claims 1 to 11.