TW202138534A - Polishing composition - Google Patents

Abstract

Provided is a polishing composition capable of improving a surface quality of a polished object. A polishing composition includes abrasive grains, a water-soluble copolymer, a basic compound and water. The water-soluble copolymer is a copolymer having an N-(meth)acryloylmorpholine unit and a vinyl alcohol unit.

Description

Polishing composition

The present invention relates to a polishing composition. In addition, this application claims priority based on Japanese Patent Application No. 2020-044111 filed on March 13, 2020, and the entire content of this application is referred to and incorporated in this specification.

The surface of materials such as metal, semi-metal, non-metal, and oxides thereof is precisely polished using a polishing composition. For example, the surface of a silicon wafer used as a constituent element of a semiconductor product generally undergoes a polishing step (rough polishing step) and a polishing step (precision polishing step) to make a high-quality mirror surface. The above-mentioned polishing step typically includes a preliminary polishing step (preliminary polishing step) and a final polishing step (final polishing step). Regarding the technical literature used for the purpose of polishing a semiconductor substrate such as a silicon wafer, for example, Patent Literature 1 can be cited. [Prior Technical Literature] [Patent Literature]

[Patent Document 1] International Publication No. 2018/043504 [Patent Document 2] Japanese Patent No. 6133271

[The problem to be solved by the invention]

The polishing composition used for polishing of semiconductor substrates such as silicon wafers and other substrates is required to achieve high-quality surface performance after polishing. In addition to abrasive grains and water, the polishing composition for this application can use water-soluble polymers for the purpose of protecting the surface of the object to be polished or improving wettability. The above-mentioned water-soluble polymer adsorbs or desorbs abrasive grains or objects to be polished, and contributes to the reduction of defects or haze on the polished surface. For example, in Patent Document 1, it was reviewed as the above-mentioned water-soluble polymer to use a graft copolymer with polyvinyl alcohol as the main chain and polyethylene oxide as the side chain, or the absence of vinyl alcohol and N-vinylpyrrolidone. Regular copolymer. In Patent Document 2, a graft copolymer of vinyl alcohol and N-vinylpyrrolidone is used.

In addition, in the above-mentioned substrate polishing, for example, in the final polishing step (especially the final polishing step of semiconductor substrates such as silicon wafers and other substrates), a higher-quality polishing surface is required to provide a substrate surface that can effectively achieve lower haze. The polishing composition is practically useful. Therefore, the object of the present invention is a polishing composition that can improve the surface quality of an object to be polished after polishing. [Means to solve the problem]

The polishing composition provided in this specification includes abrasive grains, water-soluble copolymers, basic compounds, and water. Furthermore, the aforementioned water-soluble copolymer is a copolymer having an N-(meth)acryloylmorpholine unit and a vinyl alcohol unit. According to the polishing composition of the above composition, the surface quality of the polishing object after polishing can be improved. For example, haze can be improved.

In addition, in this specification, "N-(meth)acryloylmorpholine unit" (hereinafter also referred to as "ACMO unit") means (meth)acrylic acid equivalent to N-(meth)acryloylmorpholine The structural part of the structure produced by the polymerization of the acyl group can also be referred to as a repeating unit (structural unit) derived from N-(meth)acryloylmorpholine. In addition, "vinyl alcohol unit" (hereinafter also referred to as "VA unit") refers to a _{structural part represented by the following chemical formula: -CH 2} -CH(OH)-;.

The above-mentioned water-soluble copolymer preferably has a weight average molecular weight of 1×10 ⁴ or more. When it is based on the polishing composition containing the above-mentioned copolymer having the above-mentioned weight average molecular weight (Mw), it is more suitable to exhibit the haze improvement effect.

It is preferable to use silica particles as the above-mentioned abrasive grains. The haze-improving effect of the use of the above-mentioned copolymer is suitable for use in polishing using silica particles as abrasive particles.

In some aspects, the polishing composition further contains a surfactant or a water-soluble polymer. In addition to the above-mentioned copolymers, by using a polishing composition containing a surfactant or a water-soluble polymer, the haze of the surface of the polishing object after polishing can be more effectively improved.

In some preferable aspects, the polishing composition contains a polyoxyalkylene structure-containing surfactant or an oxyalkylene-based polymer as the above-mentioned surfactant or water-soluble polymer. By using the polishing composition of this composition, it is more suitable for improving the haze.

The polishing composition disclosed here is preferably used in the final polishing step of the silicon wafer. By using the above-mentioned polishing composition for final polishing, the haze can be improved, and it can be suitable for realizing high-quality silicon wafer surfaces. [The form of implementing the invention]

The preferred embodiment of the present invention will be described. In addition, matters other than matters not specifically mentioned in this specification, and matters necessary for the implementation of the present invention, can be grasped as a basis for design matters by those familiar with the art. The present invention can be implemented based on the content disclosed in this specification and common technical knowledge in the field.

＜Polishing composition＞ (Abrasive grain) The polishing composition disclosed here contains abrasive grains. The abrasive grains have a function of mechanically polishing the surface of an object to be polished. The material or properties of the abrasive grains are not particularly limited, and can be appropriately selected according to the purpose of use or usage of the polishing composition. Examples of abrasive particles include inorganic particles, organic particles, and organic-inorganic composite particles. Specific examples of inorganic particles include silicon dioxide particles, aluminum oxide particles, cerium oxide particles, chromium oxide particles, titanium dioxide particles, zirconium oxide particles, magnesium oxide particles, manganese dioxide particles, zinc oxide particles, iron oxide red particles, etc. Nitride particles such as silicon nitride particles and boron nitride particles; carbide particles such as silicon carbide particles and boron carbide particles; diamond particles; carbonates such as calcium carbonate or barium carbonate. Specific examples of organic particles include polymethylmethacrylate (PMMA) particles or poly(meth)acrylic acid particles (here, (meth)acrylic acid includes acrylic acid and methacrylic acid), polyacrylonitrile particles Wait. Such abrasive grains can be used singly or in combination of two or more kinds.

The above-mentioned abrasive particles are preferably inorganic particles, and among them, particles composed of metal or semimetal oxides are preferred, and silicon dioxide particles are particularly preferred. For example, in the polishing composition that can be used for polishing (for example, final polishing) of a polishing object having a surface made of silicon, such as a silicon wafer, described later, it is particularly meaningful to use silicon dioxide particles as the abrasive. The technology disclosed herein, for example, the above-mentioned abrasive grains are preferably implemented in a state substantially composed of silicon dioxide particles. Here, "substantially" means that 95% by weight or more (preferably 98% by weight or more, more preferably 99% by weight or more, and may be 100% by weight) of the particles constituting the abrasive particles are silica particles.

Specific examples of silica particles include colloidal silica, smoked silica, precipitated silica, and the like. The silicon dioxide particles can be used alone or in combination of two or more. Since it is easy to obtain a polished surface with excellent surface quality after polishing, it is particularly preferable to use colloidal silica. Colloidal silica is preferably used, for example, by ion exchange method, colloidal silica made from water glass (silicate Na) as raw material, or colloidal silica made by alkoxide method (by alkoxysilane The colloidal silica produced by the hydrolysis and condensation reaction). The colloidal silica can be used alone or in combination of two or more.

The true specific gravity of the abrasive grain constituent material (for example, the silicon dioxide constituting the silicon dioxide particles) is preferably 1.5 or more, more preferably 1.6 or more, and still more preferably 1.7 or more. The upper limit of the true specific gravity of silicon dioxide is not particularly limited, but is typically 2.3 or less, for example, 2.2 or less, 2.0 or less, or 1.9 or less. The true specific gravity of abrasive particles (such as silica) can be measured by a liquid displacement method using ethanol as a displacement fluid.

The average primary particle size of the abrasive grains (for example, silica particles) is not particularly limited, but from the viewpoint of polishing speed and the like, it is preferably 5 nm or more, and more preferably 10 nm or more. From the viewpoint of obtaining a higher polishing effect (for example, the effect of haze reduction, defect removal, etc.), the average primary particle size is preferably 15 nm or more, and more preferably 20 nm or more (for example, more than 20 nm). In addition, from the viewpoint of scratch prevention, etc., the average primary particle size of the abrasive grains is preferably 100 nm or less, more preferably 50 nm or less, and still more preferably 40 nm or less. From the point of view that it is easy to obtain a surface with a lower haze, among several aspects, the average primary particle size of the abrasive grains may be 35 nm or less, may be less than 32 nm, or may be less than 30 nm.

In this specification, the average primary particle size refers to the specific surface area (BET value) measured by the BET method, and the average primary particle size (nm) = 6000/(true density (g/cm ³ ) × BET value ( m ² /g)) The particle size (BET particle size) calculated by the formula. The above-mentioned specific surface area can be measured using, for example, a surface area measuring device manufactured by Micromeritex, trade name "Flow Sorb II 2300".

The average secondary particle diameter of the abrasive grains (for example, silica particles) is not particularly limited, and can be appropriately selected, for example, in the range of about 15 nm to 300 nm. From the viewpoint of improving the polishing efficiency, the average secondary particle size is preferably 30 nm or more. More preferably, it is 35 nm or more. In some aspects, the average secondary particle size may be, for example, 40 nm or more, 42 nm or more, and preferably 44 nm or more. In addition, the above-mentioned average secondary particle size may usually be 250 nm or less, preferably 200 nm or less, and more preferably 150 nm or less. In several preferred aspects, the average secondary particle size may also be 120 nm or less, more preferably 100 nm or less, and still more preferably 70 nm or less, for example, 60 nm or less, or 50 nm or less.

In addition, in this specification, the average secondary particle size refers to the particle size (volume average particle size) measured by the dynamic light scattering method. The average secondary particle size of the abrasive grains can be measured, for example, by a dynamic light scattering method using "Nanotrac (registered trademark) UPA-UT151" manufactured by Nikkiso Co., Ltd.

The shape (shape) of the abrasive grains can be spherical or non-spherical. Specific examples of the non-spherical particles include a peanut shape (that is, the shape of a peanut shell), a cocoon shape, a kumira candy shape, and a rugby ball shape. For example, it is preferable to use abrasive grains in which most of the particles are in a peanut shape or a cocoon shape.

It is not particularly limited, and the principle of the average of the long-diameter/short-diameter ratio (average long-to-short axis ratio) of the abrasive grains is 1.0 or more, preferably 1.05 or more, and more preferably 1.1 or more. By increasing the average long-to-short axis ratio, a higher polishing speed can be achieved. In addition, the average long-to-short axis ratio of the abrasive grains is preferably 3.0 or less, more preferably 2.0 or less, and still more preferably 1.5 or less from the viewpoint of reduction of scratches.

The shape (outline) or the average long-to-short axis ratio of the abrasive grains can be grasped by observation with an electron microscope, for example. Grasp the specific order of the average length-to-minor axis ratio. For example, using a scanning electron microscope (SEM), you can recognize a specific number (for example, 200) of abrasive particles in an independent particle shape, and draw the smallest circumscribed particle image. rectangle. Then, for the rectangle drawn by each particle image, the length of the long side (the value of the long axis) is divided by the length of the short side (the value of the short axis) to obtain the value. Calculate as the ratio of long diameter to short diameter (ratio of long and short axis). The arithmetic average of the long-to-short axis ratios of the above-mentioned specific number of particles can obtain the average long-to-short axis ratio.

The content of abrasive grains in the polishing composition is not particularly limited. For example, it is 0.01% by weight or more, preferably 0.05% by weight or more, more preferably 0.10% by weight or more, and still more preferably 0.15% by weight or more. By increasing the content of abrasive particles, a higher polishing speed can be achieved. The above content is suitably 10% by weight or less, preferably 7% by weight or less, more preferably 5% by weight or less, and still more preferably 2% by weight or less, for example, may be 1% by weight or less, or may be 0.5% by weight or less. In this way, a surface with lower haze can be achieved. The content of the abrasive grains can preferably be used when the polishing composition is used in the form of a polishing liquid.

(Water-soluble copolymer) The polishing composition system disclosed here includes a copolymer having N-(meth)acryloylmorpholine units (ACMO units) and vinyl alcohol units (VA units) as a water-soluble copolymer. By using the above-mentioned water-soluble copolymer for polishing, the surface quality of the polishing object after polishing is improved. The reason is that the water-soluble copolymer having the above-mentioned structure has two units with different chemical structures that exhibit different effects (adsorption) on abrasive grains or objects to be polished. As a molecule of the water-soluble copolymer, it is effective for polishing. Granules or objects to be polished exhibit moderate adsorptivity, which greatly contributes to the improvement of the surface quality of the objects to be polished after polishing. However, the effect of the water-soluble copolymer disclosed here is not limited to the above explanation.

The ratio of ACMO units in the above copolymer, from the viewpoint of showing the effect of containing ACMO units, may be 1 mol% or more, and more suitably 5 mol% or more. Among several aspects, the ratio of ACMO units in the above copolymers, from the viewpoint of effectively exerting the effect of containing ACMO units, is preferably 10 mol% or more, more preferably 20 mol% or more, and still more preferably 30 mol% or more ( For example, more than 40mol%). In several preferred aspects, the ratio of ACMO units in the above copolymers, from the viewpoint of obtaining a more excellent haze improvement effect, is 50 mol% or more, more preferably 70 mol% or more, and still more preferably 80 mol% or more , Particularly preferred is more than 85mol%. By increasing the ratio of ACMO units, the polishing composition can impart good etching resistance to the wafer. The upper limit of the ratio of ACMO units in the above copolymers is to exhibit the effect of structural units other than ACMO units such as VA units. The upper limit is preferably 99 mol% or less, preferably 97 mol% or less, and more preferably 95 mol% or less , More preferably 92 mol% or less, particularly preferably 90 mol% or less. In several aspects, the proportion of ACMO units in the above copolymer may also be 80 mol% or less, 65 mol% or less, 45 mol% or less, or 25 mol% or less.

The ratio of the VA unit in the above copolymer can be 0.1 mol% or more, and more suitably 1 mol% or more, from the viewpoint of exhibiting the effect of containing VA units. Among several aspects, the ratio of the VA unit in the above-mentioned copolymer, from the viewpoint of obtaining a more excellent haze improvement effect, is preferably 2 mol% or more, more preferably 3 mol% or more, and still more preferably 5 mol% or more, Especially preferably, it is 8 mol% or more (for example, 10 mol% or more). In some aspects, the proportion of VA units in the above copolymer may be 20 mol% or more, 40 mol% or more, 60 mol% or more, or 80 mol% or more. The upper limit of the ratio of the VA unit in the above-mentioned copolymer can be 95 mol% or less, 80 mol% or less, or 60 mol% or less from the viewpoint of exhibiting the effect of structural units other than VA units such as ACMO units. , It may be 50 mol% or less, or 40 mol% or less. In several preferable aspects, the ratio of the VA unit in the above copolymer is 30 mol% or less, more preferably 20 mol% or less, and even more preferably 15 mol% or less, from the viewpoint of obtaining an excellent haze improvement effect. It may be 10 mol% or less.

In addition, in this specification, the ratio (mol%) of structural units such as ACMO units and VA units constituting the water-soluble copolymer refers to the number of moles of all repeating units (monomer units) constituting one molecule of the water-soluble copolymer The ratio of the number of moles of each structural unit occupied in.

In the water-soluble copolymer disclosed herein, the ratio of the ACMO unit to the VA unit can be appropriately set to enable the function of each structural unit, so it is not limited to a specific range. In the above water-soluble copolymer, the molar ratio (ACMO:VA) of the ACMO unit to the VA unit may be 1:99 or more. From the viewpoint of effectively exerting the effect of the ACMO unit, the above-mentioned molar ratio (ACMO: VA) is preferably 5:95 or more, more preferably 10:90 or more, still more preferably 20:80 or more, particularly preferably 30 : 70 or more (for example, 40:60 or more). Among several preferable aspects, the above-mentioned molar ratio (ACMO: VA), from the viewpoint of obtaining a more excellent haze improvement effect, can be 50:50 or more, more preferably 70:30 or more, and still more preferably Above 80:20, especially preferably above 85:15. By increasing the ratio of ACMO units, the polishing composition can impart good etching resistance to the wafer. The upper limit of the above-mentioned molar ratio (ACMO: VA) can be 99.9: 0.1 or less, 99:1 or less is more appropriate, preferably 97: 3 or less, more preferably 95: 5 or less, and even more preferably 92: 8 or less , Particularly preferably less than 90:10. Among several aspects, the above-mentioned molar ratio (ACMO: VA) may be 80:20 or less, 65:35 or less, 45:55 or less, or 25:75 or less.

The total ratio of ACMO units and VA units constituting the water-soluble copolymer disclosed herein is effective in showing the effect of including ACMO units and VA units. 50 mol% or more (for example, more than 50 mol%) is more appropriate, and it is preferably 70 mol% or more, more preferably 80 mol% or more, still more preferably 90 mol% or more, particularly preferably 95 mol% or more (for example, 99-100 mol%).

In addition to ACMO units and VA units, the water-soluble copolymers disclosed herein may also have structural units derived from other monomers that can be copolymerized with these. Other monomers are not particularly limited, and examples include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, etc. ( Alkyl meth)acrylates; (poly)ethylene glycol mono(meth)acrylate, (poly)propylene glycol mono(meth)acrylate and other alkylene glycol (meth)acrylates; Unsaturated acids such as meth)acrylic acid, crotonic acid, maleic acid, itaconic acid and fumaric acid and alkyl esters thereof; unsaturated acid anhydrides such as maleic anhydride; 2-propenamide-2- Sulfonic acid group-containing monomers such as methyl propane sulfonic acid and its salts; methyl (meth) acrylamide, ethyl (meth) acrylamide, n-propyl (meth) acrylamide , N-alkyl (meth)acrylamide such as isopropyl (meth)acrylamide, n-butyl (meth)acrylamide and 2-ethylhexyl (meth)acrylamide; Methylaminopropyl (meth)acrylamide, dimethylaminopropyl (meth)acrylamide, ethylaminopropyl (meth)acrylamide, and diethylaminopropyl (Meth) acrylamide and other (two) alkylaminoalkyl amides; methylaminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, ethyl (Di)alkylaminoalkyl (meth)acrylates such as diethylaminoethyl (meth)acrylate and diethylaminoethyl (meth)acrylate; N-vinylpyrrolidone, N-vinylpiperidone, N-vinylmorpholinone, N-vinylcaprolactam, N-vinyl-1,3-oxazin-2-one, N-vinyl-3,5- N-vinyl lactam-type monomers such as morpholinedione; N-vinyl chain like N-vinyl acetamide, N-vinyl propionate amide, N-vinyl butyrate amide, etc. Amide; N-(meth)acryloylpyrrolidine and other cyclic amides with N-(meth)acryloyl groups other than ACMO; aromatics such as styrene, vinyl toluene and vinyl xylene Vinyl compounds; methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, t-butyl vinyl ether, n-hexyl Vinyl ether, 2-ethylhexyl vinyl ether, n-octyl vinyl ether, n-nonyl vinyl ether, n-decyl vinyl ether, and other alkyl vinyl ethers having a C 1-10 alkyl group; formic acid Vinyl ester, vinyl acetate, vinyl propionate, vinyl valerate, vinyl decanoate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl trimethyl acetic acid (Pivalic acid) vinyl ester and tertiary Vinyl ester compounds such as ethylene carbonate; α-olefins such as ethylene, propylene, butene, etc., and one or two or more of these can be used.

The use amount of other monomers in the above water-soluble copolymer can be 50 mol% or less (for example, less than 50 mol%), for example, 30 mol% or less, preferably 20 mol% or less, more preferably 10 mol% or less, and more preferably It is 5 mol% or less (for example, 0 to 1 mol%).

The copolymerization form of the water-soluble copolymer disclosed herein is not particularly limited. The water-soluble copolymer can be a block copolymer or graft copolymer, random copolymer, alternating copolymer, etc. having ACMO units and VA units. In any form, a block copolymer is preferable.

In several preferred aspects, the water-soluble copolymer contains PACMO (poly-N-(meth)acryloylmorpholine) fragments with ACMO units as the main repeating unit (main structural unit) and VA units as the A copolymer of PVA (polyvinyl alcohol) segments of the main repeating unit (main structural unit). In addition, in this specification, the main repeating unit refers to the repeating unit (structural unit) that occupies the largest proportion of all repeating units (monomer units) constituting the segment on a molar basis, unless otherwise specified.

The water-soluble copolymer having a PACMO segment and a PVA segment has a structure including at least one PACMO segment and at least one PVA segment in the same molecule. The above-mentioned water-soluble copolymer may be, for example, a random copolymer, a block copolymer, or a graft copolymer containing a PACMO segment and a PVA segment. The structure of the above-mentioned block copolymer is not particularly limited, and may be in the form of a diblock, a triblock, a radial, a mixture of these, and the like. From the viewpoint of being suitable for exhibiting the function of each segment, the water-soluble copolymer preferably contains a diblock body. In addition, the structure of the above-mentioned graft copolymer is not particularly limited. For example, it may be a graft copolymer in which a PVA segment (side chain) is grafted to a PACMO segment (main chain), or it may be a PVA segment (main chain). A graft copolymer with the structure of grafted PACMO segment (side chain).

[PACMO snippet] The PACMO fragment may also include only ACMO units as repeating units, or may be non-ACMO units including ACMO units and repeating units derived from monomers other than ACMO. In the case where the PACMO fragment contains a non-ACMO unit, the non-ACMO unit may, for example, have an oxyalkylene group, a carboxyl group, a sulfonic acid group, an amine group, a hydroxyl group, an amide group, an amide group, a nitrile group, and an ether group. A repeating unit of at least one structure of a group, an ester group, and these salts. The PACMO fragment can also contain only one type of non-ACMO unit, or more than two types of non-ACMO units. Examples of non-ACMO units that the PACMO fragment may contain include structural units or VA units derived from other monomers that can be copolymerized with the above-mentioned ACMO units and VA units.

The ratio of the molar number of the ACMO unit occupied by the molar number of the total repeating unit constituting the PACMO fragment is, for example, 50% or more (for example, more than 50%), preferably 70% or more, and preferably 80% or more. In several preferred aspects, the ratio of the molar number of ACMO unit occupied by the molar number of all repeating units constituting the PAMO fragment can be, for example, 90% or more, 95% or more, or 98 %above. In fact, 100% of the repeating units constituting the PACMO fragment can be ACMO units. Here, "substantially 100%" means that at least it is intended to not contain non-ACMO units as PACMO fragments.

[PVA fragment] The PVA fragment may contain only the VA unit as a repeating unit, or may contain a VA unit and a non-VA unit other than the VA unit. In the case where the PVA fragment contains a non-VA unit, the non-VA unit may have, for example, an oxyalkylene group, a carboxyl group, a sulfonic acid group, an amino group, a hydroxyl group, an amide group, an amide group, a nitrile group, A repeating unit of at least one structure of an ether group, an ester group, and these salts. The PVA fragment may contain only one type of non-VA unit, or may contain two or more types of non-VA unit. Examples of non-VA units that the PVA fragment may contain include structural units or ACMO units derived from other monomers that can be copolymerized with the above-mentioned ACMO units and VA units.

The ratio of the molar number of the VA unit occupied by the molar number of the total repeating unit constituting the PVA fragment is, for example, 50% or more (for example, more than 50%), preferably 70% or more, and preferably 80% or more. In several preferred aspects, the ratio of the molar number of the VA unit occupied by the molar number of all repeating units constituting the PVA fragment can be, for example, 90% or more, 95% or more, or 98 %above. Substantially, 100% of the repeating units constituting the PVA fragment can be VA units. Here, "substantially 100%" refers to at least the intention to exclude non-VA units as PVA segments.

The water-soluble copolymer can be obtained by conventional methods (specifically, various polymerization methods) or commercially. For example, a water-soluble copolymer having ACMO units and VA units can be copolymerized by copolymerization of monomers (such as vinyl ester compounds such as vinyl acetate) that can be converted into VA units and N-(meth)acryloylmorpholine (Random copolymer, block copolymer, graft copolymer). For example, by partially saponifying or completely saponifying a block copolymer of vinyl acetate and N-(meth)acrylomorpholine, a copolymer containing ACMO units and VA units can be obtained.

The weight average molecular weight (Mw) of the water-soluble copolymer disclosed herein is not particularly limited. For example, it may be 2×10 ³ or more, 1×10 ⁴ or more, and more suitably 5.0×10 ⁴ or more. ^{The above-mentioned Mw is preferably 1.0×10 5} or more, more preferably 2.0×10 ⁵ or more, still more preferably 3.0×10 ⁵ or more, particularly ^{preferably 4.5×10 5} or more from the viewpoint of surface protection of the object to be polished. , It can also exceed 4.5×10 ⁵ . The water-soluble copolymer disclosed here can well disperse abrasive grains even if it has a relatively high molecular weight (for example, Mw is about 300,000 or more). The upper limit of the above-mentioned Mw is, for example, 10×10 ⁵ or less, and more suitably 8.0×10 ⁵ or less. From the viewpoint of the adsorbability to abrasive grains, etc., it is preferably 7.0×10 ⁵ or less, more preferably 6.0×10 ⁵ or less, and may also be 5.0×10 ⁵ or less. In addition, in this specification, the weight average molecular weight (Mw) and number average molecular weight (Mn) of the water-soluble copolymer, other water-soluble polymers and surfactants described later can be based on gel permeation chromatography (GPC). Value (in terms of polymethyl methacrylate). The GPC measuring device can use the model name "HLC-8320GPC" manufactured by Tosoh Corporation. The measurement can be performed using the following conditions, for example. The same method can also be adopted for the embodiments described later. [GPC measurement conditions] Sample concentration: 0.1% by weight Column: TSKgel SuperHM-M×3 This detector: RI Leachate: N,N-dimethylformamide (10mM LiBr content) Flow rate: 300μL/min Measurement temperature ：40℃ Sample injection volume: 200μL

The content of the water-soluble copolymer in the polishing composition is not particularly limited, and may be, for example, 1.0×10 ^-4 % by weight or more. From the viewpoint of haze reduction, etc., the content is preferably 5.0×10 ^-4 % by weight or more, more preferably 1.0×10 ^-3 % by weight or more, and still more preferably 2.0×10 ^-3 % by weight or more. For example, it may be 5.0×10 ^-3 % by weight or more, or 8.0×10 ^-3 % by weight or more. In addition, from the viewpoint of polishing speed and the like, the above content is preferably 0.2% by weight or less, more preferably 0.1% by weight or less, still more preferably 0.05% by weight or less, and may also be 0.02% by weight or less (for example, 0.01% by weight or less) . In addition, when the polishing composition contains two or more water-soluble copolymers, the content refers to the total content (weight-based content) of all the water-soluble copolymers contained in the polishing composition. The content of the water-soluble copolymer is preferably a state in which the polishing composition is used as a polishing liquid.

The content of the water-soluble copolymer (when two or more water-soluble copolymers are contained, the total amount of them) can be defined by the relative relationship with the abrasive grains. It is not particularly limited, but in some aspects, the content of the water-soluble copolymer relative to 100 parts by weight of the abrasive grains may be, for example, 0.01 parts by weight or more. It is preferably 0.5 part by weight or more, more preferably 1 part by weight or more, still more preferably 3 parts by weight or more, for example, 4 parts by weight or more. In addition, the content of the water-soluble copolymer relative to 100 parts by weight of the abrasive grains may be 50 parts by weight or less, or 30 parts by weight or less, for example. From the viewpoint of the dispersion stability of the polishing composition, among several aspects, the content of the water-soluble copolymer relative to 100 parts by weight of the abrasive grains is preferably 15 parts by weight or less, preferably 10 parts by weight or less, and more It is preferably 8 parts by weight or less, and may be 7 parts by weight or less.

＜Basic compound＞ The polishing composition disclosed here contains a basic compound. In this specification, a basic compound refers to a compound that is dissolved in water and has the function of increasing the pH of an aqueous solution. As the basic compound, nitrogen-containing organic or inorganic basic compounds, phosphorus-containing basic compounds, alkali metal hydroxides, alkaline earth metal hydroxides, various carbonates or bicarbonates can be used. Examples of nitrogen-containing basic compounds include quaternary ammonium compounds, ammonia, amines (preferably water-soluble amines), and the like. Phosphorus-containing basic compounds include quaternary phosphonium compounds. Such basic compounds can be used singly or in combination of two or more.

Specific examples of alkali metal hydroxides include potassium hydroxide and sodium hydroxide. Specific examples of carbonate or bicarbonate include ammonium bicarbonate, ammonium carbonate, potassium bicarbonate, potassium carbonate, sodium bicarbonate, sodium carbonate, and the like. Specific examples of amines include methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, ethylenediamine, monoethanolamine, N-(β-aminoethyl Base) ethanolamine, hexamethylene diamine, ethylene triamine, ethylene tetramine, anhydrous piperazine, piperazine hexahydrate, 1-(2-aminoethyl) piperazine, N-methylpiperazine, Azoles such as guanidine, imidazole or triazole. Specific examples of the quaternary phosphonium compound include quaternary phosphonium hydroxide such as tetramethylphosphonium hydroxide and tetraethylphosphonium hydroxide.

As the quaternary ammonium compound, quaternary ammonium salts (typically strong bases) such as tetraalkylammonium salts and hydroxyalkyltrialkylammonium salts can be used. This anionic component of the quaternary ammonium salt, for example as ^{OH -, F -, Cl -} , Br -, I -, ClO 4 -, BH 4 - and the like. Examples of quaternary ammonium compounds include ^{quaternary ammonium salts whose anions are OH -} , that is, quaternary ammonium hydroxide. Specific examples of quaternary ammonium hydroxide include hydrogen such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetrapentylammonium hydroxide, and tetrahexylammonium hydroxide. Tetraalkylammonium oxide; 2-hydroxyethyltrimethylammonium hydroxide (also called choline) and other hydroxyalkyltrialkylammonium hydroxides; etc.

Among these basic compounds, for example, it is preferable to use at least one basic compound selected from alkali metal hydroxides, quaternary ammonium hydroxides, and ammonia. Among them, more preferred are tetraalkylammonium hydroxide (for example, tetramethylammonium hydroxide) and ammonia, and particularly preferred is ammonia.

The concentration of the basic compound in the polishing composition disclosed herein is not particularly limited. From the viewpoint of polishing rate and the like, the above-mentioned concentration is suitably 0.0005% by weight or more, and preferably 0.001% by weight or more. In addition, from the viewpoint of haze reduction, etc., the aforementioned concentration is suitably less than 0.3% by weight, preferably less than 0.1% by weight, and more preferably less than 0.05% by weight (for example, less than 0.025% by weight). The polishing composition is used in the form of a polishing liquid, and it is preferable to adopt the above-mentioned alkaline compound concentration.

＜Surface active agent＞ The polishing composition disclosed here may contain a surfactant when necessary. By including a surfactant in the polishing composition, it is possible to further reduce the haze on the surface of the polishing object after polishing. As the surfactant, any of anionic, cationic, nonionic, and amphoteric can be used. Preferably, an anionic or nonionic surfactant is used. From the viewpoint of low foamability and ease of pH adjustment, a nonionic surfactant is more preferable. Examples include alkylene oxide polymers such as polyethylene glycol, polypropylene glycol, and polybutylene glycol; polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene alkyl amines, polyoxyethylene fatty acid esters, Polyoxyalkylene derivatives of polyoxyethylene glyceryl ether fatty acid esters, polyoxyethylene sorbitan fatty acid esters, etc. (for example, polyoxyalkylene adducts); copolymers of plural kinds of alkylene oxides (for example, diblock Segment copolymers, triblock copolymers, random copolymers, interactive copolymers); and other nonionic surfactants. The aforementioned surfactant preferably includes a surfactant containing a polyoxyalkylene structure. Surfactants can be used alone or in combination of two or more.

Specific examples of nonionic surfactants containing polyoxyalkylene structure include block copolymers of ethylene oxide (EO) and propylene oxide (PO) (diblock copolymers, PEO (polyepoxy) Ethane)-PPO (polypropylene oxide)-PEO type triblock, PPO-PEO-PPO type triblock copolymer, etc.), random copolymer of EO and PO, polyoxyethylene glycol, Polyoxyethylene propyl ether, polyoxyethylene butyl ether, polyoxyethylene pentyl ether, polyoxyethylene hexyl ether, polyoxyethylene octyl ether, polyoxyethylene-2-ethylhexyl ether, polyoxyethylene nonyl ether, polyoxyethylene Decyl ether, polyoxyethylene isodecyl ether, polyoxyethylene tridecyl ether, polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene isostearyl ether, polyoxyethylene Ethylene oil ether, polyoxyethylene phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene nonyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene styrenated phenyl ether, polyoxyethylene lauryl Amine, polyoxyethylene stearylamine, polyoxyethylene oleylamine, polyoxyethylene monolaurate, polyoxyethylene monostearate, polyoxyethylene distearate, polyoxyethylene monooil Acid ester, polyoxyethylene dioleate, monolauric acid polyoxyethylene sorbitan, monopalmitic acid (Palmitic acid) polyoxyethylene sorbitan, monostearic acid polyoxyethylene sorbitan, mono Polyoxyethylene sorbitan oleic acid, polyoxyethylene sorbitan trioleic acid, polyoxyethylene sorbitol tetraoleic acid, polyoxyethylene castor oil, polyoxyethylene hardened castor oil, etc. Among the preferred surfactants, block copolymers of EO and PO (especially PEO-PPO-PEO type triblock copolymers), random copolymers of EO and PO, and polyoxyethylene alkyl ethers (such as Polyoxyethylene decyl ether).

The molecular weight of the surfactant is typically less than 2,000, and from the viewpoint of filterability or detergency, it is preferably 1900 or less (for example, less than 1800). In addition, the molecular weight of the surfactant is preferably 200 or more from the viewpoint of interfacial activity and the like, and preferably 250 or more (for example, 300 or more) from the viewpoint of the haze reduction effect. The range of the molecular weight of the surfactant is different depending on the type of the surfactant. For example, when polyoxyethylene alkyl ether is used as a surfactant, the molecular weight is preferably 1500 or less, and may be 1000 or less (for example, 500 or less). In addition, for example, when a PEO-PPO-PEO type triblock copolymer is used as a surfactant, the molecular weight may be, for example, 500 or more, 1000 or more, or 1200 or more. The molecular weight of the surfactant can be the weight average molecular weight (Mw) obtained by the above-mentioned GPC or the molecular weight calculated from the chemical formula.

When the polishing composition disclosed here contains a surfactant, its content is not particularly limited as long as it does not significantly hinder the effects of the present invention. From the standpoint of detergency, etc., relative to 100 parts by weight of abrasive grains, the content of the surfactant is suitably 20 parts by weight or less, preferably 15 parts by weight or less, and more preferably 10 parts by weight or less (for example, 6 parts by weight) the following). From the viewpoint of more effective use of the surfactant, relative to 100 parts by weight of the abrasive grains, the content of the surfactant is preferably 0.001 parts by weight or more, preferably 0.005 parts by weight or more, and may also be 0.01 parts by weight or more. It may be 0.05 parts by weight or more.

When the polishing composition disclosed herein contains a surfactant, the weight ratio (W _A /W _{B ) of the content of the water-soluble copolymer W A} to the content of the surfactant W _B is not particularly limited, for example, it can be 0.01~ The range of 200 is preferably the range of 0.05 to 100, and more preferably the range of 0.1 to 80. Or from the viewpoint of simplification of the composition, etc., the polishing composition disclosed here can also be implemented in a state that does not substantially contain a surfactant.

(water) The water contained in the polishing composition disclosed here is preferably ion-exchanged water (deionized water), pure water, ultrapure water, distilled water, or the like. In order to avoid hindering the effects of other components contained in the polishing composition as much as possible for the water used, for example, the total content of transition metal ions is preferably 100 ppb or less. For example, the purity of water can be improved by operations such as removing impurity ions with ion exchange resin, removing foreign matter with a filter, and distillation.

(Other water-soluble polymers) The polishing composition disclosed herein may contain other water-soluble polymers if necessary, within a range that does not significantly hinder the effects of the present invention, that is, if necessary, it may further contain water-soluble polymers other than the above-mentioned water-soluble copolymers. . Other water-soluble polymers. Water-soluble polymers known in the field of polishing compositions can be appropriately selected. As examples of other water-soluble polymers, for example, vinyl alcohol-based polymers, oxyalkylene-based polymers, N-vinyl-based polymers, N-(meth)acrylic acid-based polymers, etc. can be used. Examples of vinyl alcohol polymers include polyvinyl alcohol (PVA) or modified PVA. Examples of oxyalkylene polymers include polymers containing oxyalkylene units such as block copolymers of ethylene oxide (EO) and propylene oxide (PO). The N-vinyl polymer can be a homopolymer or copolymer of N-vinyl monomers. Specific examples of the N-vinyl polymer include a homopolymer of N-vinylpyrrolidone (VP) or a copolymer in which the copolymerization ratio of VP is 70% by weight or more. The N-(meth)acrylic acid-based polymer may be a homopolymer or copolymer of an N-(meth)acrylic acid-based monomer. Specific examples of N-(meth)acrylic acid-based polymers include homopolymers of N-isopropylacrylamide (NIPAM), copolymers in which the copolymerization ratio of NIPAM is 70% by weight or more, and N- Homopolymer or copolymer of acrylomorpholine (ACMO), etc. For other water-soluble polymers, homopolymers and copolymers of N-Alkaneimine monomers can be used. For other water-soluble polymers, in addition to the above-mentioned synthetic polymers, cellulose derivatives such as hydroxyethyl cellulose or polymers derived from natural products such as starch derivatives can be used. The above-mentioned other water-soluble polymers can be used singly or in combination of two or more.

In the technique disclosed herein, the weight average molecular weight (Mw) of other water-soluble polymers is not particularly limited. The weight average molecular weight (Mw) of other water-soluble polymers can be, for example, 100×10 ⁴ or less. From the viewpoint of detergency, 60×10 ⁴ or less is more appropriate, and 30×10 ⁴ or less is also preferable. It is 20×10 ⁴ or less, for example, it may be 10×10 ⁴ or less, or it may be 8×10 ⁴ or less. In addition, from the viewpoint of the protection of the object to be polished, the Mw of other water-soluble polymers may be, for example, 2000 or more, and preferably 5000 or more. Among some aspects, the above-mentioned Mw is preferably 1.0×10 ⁴ or more, and may be 2×10 ⁴ or more, for example, 5×10 ⁴ or more.

From the viewpoint of reduction of aggregates or improvement of detergency, other water-soluble polymers are preferably nonionic polymers. In addition, from the viewpoint of the ease of control of the chemical structure or purity, it is preferable to adopt synthetic polymers as other water-soluble polymers. The polishing composition disclosed herein is preferably implemented in a state in which a natural product-derived polymer, which is another water-soluble polymer, is not used substantially.

When the polishing composition contains other water-soluble polymers, the content of other water-soluble polymers is based on 100 parts by weight of the above-mentioned water-soluble copolymer, usually less than 100 parts by weight and less than 50 parts by weight. Where appropriate, it may be less than 30 parts by weight, less than 20 parts by weight, less than 10 parts by weight, or less than 5 parts by weight. In addition, the content of other water-soluble polymers in 100 parts by weight of the above-mentioned water-soluble copolymer is 0.01 parts by weight or more, preferably 0.1 parts by weight or more, and may be 1 part by weight or more, for example, 3 parts by weight or more. In addition, the technique disclosed here is also suitable for implementation without substantially containing other water-soluble polymers. In addition, substantially no use, substantially no content refers to the amount used relative to 100 parts by weight of the content of the water-soluble copolymer, typically 3 parts by weight or less, preferably 1 part by weight or less, including 0 parts by weight or Below the detection limit.

(Other ingredients) The polishing composition disclosed herein may further contain chelating agents, organic acids, organic acid salts, inorganic acids, inorganic acid salts, preservatives, and antifungal agents, if necessary, within a range that does not significantly hinder the effects of the present invention. Well-known additives can be used for the polishing composition (for example, the polishing composition that can be used in the final polishing step of a silicon wafer).

The polishing composition disclosed here preferably contains substantially no oxidizing agent. When an oxidizing agent is contained in the polishing composition, for example, during polishing of a silicon wafer, the surface of the silicon wafer is oxidized to produce an oxide film, so the polishing time required becomes longer. Specific examples of the oxidizing agent here include hydrogen peroxide (H ₂ O ₂ ), sodium persulfate, ammonium persulfate, sodium dichloroisocyanurate, and the like. In addition, that the polishing composition does not substantially contain an oxidizing agent means that it does not contain an oxidizing agent at least deliberately. Therefore, it is derived from raw materials or manufacturing methods, and contains unavoidable trace amounts (for example, the molar concentration of the oxidizing agent in the polishing composition is 0.0005 mol/L or less, preferably 0.0001 mol/L or less, and more preferably 0.00001 mol/L. Ears/L or less, particularly preferably 0.000001 mol/L or less) of the polishing composition of an oxidizing agent is also included in the concept of a polishing composition that does not substantially contain the so-called oxidizing agent.

(pH) The pH of the polishing composition disclosed here is suitably 8.0 or higher, preferably 8.5 or higher, and more preferably 9.0 or higher. When the pH of the polishing composition becomes higher, there is a tendency to increase the polishing speed. In addition, from the viewpoint of preventing the dissolution of abrasive particles (such as silica particles) and suppressing the reduction of the mechanical polishing effect, the pH of the polishing composition is preferably 12.0 or less, preferably 11.0 or less, more preferably 10.8 or less, and It is more preferably 10.6 or less, and for example, it may be 10.3 or less.

Use a pH meter (for example, a glass electrode hydrogen ion concentration indicator (model F-23) manufactured by Horiba Manufacturing Co., Ltd.), and use a standard buffer (phthalate pH buffer pH: 4.01 (25°C), medium Phosphate pH buffer solution pH: 6.86 (25°C), carbonate pH buffer solution pH: 10.01 (25°C)) After 3-point calibration, the glass electrode is placed in the composition of the object to be measured, and the measurement has elapsed for more than 2 minutes Confirm the pH after stabilization.

＜Lapping liquid＞ The polishing composition disclosed here is typically supplied on the surface of an object to be polished in the form of a polishing liquid containing the polishing composition, and used for polishing the object to be polished. The above-mentioned polishing liquid can be prepared by diluting any one of the polishing compositions disclosed herein (typically, diluting with water). Or, the polishing composition can be used as a polishing liquid as it is. That is, the concept of the polishing composition in the technology disclosed here includes the supply of the polishing object, the polishing liquid (working slurry) used for the polishing of the polishing object, and the concentrated liquid that is diluted and used as the polishing liquid ( The original liquid of the polishing liquid).

＜Concentrate＞ The polishing composition disclosed here may be in a concentrated form (that is, the form of a concentrated liquid of the polishing liquid) before being supplied to the polishing object. The polishing composition in such a concentrated form is preferable from the viewpoints of convenience during manufacture, distribution, and storage, and cost reduction. The concentration ratio is not particularly limited. For example, it may be about 2 times to 100 times in terms of volume, and about 5 times to 50 times (for example, about 10 times to 40 times) is appropriate. Such a concentrated liquid can be used in a state where it is diluted to prepare a polishing liquid (working slurry) at a desired timing, and the polishing liquid is supplied to an object to be polished. For the above-mentioned dilution, for example, water is added to the above-mentioned concentrated solution and diluted by mixing.

The content of abrasive grains in the above-mentioned concentrated liquid may be 25% by weight or less, for example. From the viewpoint of dispersion stability and filterability of the polishing composition, the content is preferably 20% by weight or less, and more preferably 15% by weight or less. In several preferable aspects, the content of abrasive grains may be 10% by weight or less, or 5% by weight or less. In addition, from the viewpoints of convenience during production, distribution, storage, etc., or cost reduction, the content of abrasive grains in the concentrate may be, for example, 0.1% by weight or more, preferably 0.5% by weight or more, and more preferably 0.7% by weight % Or more, and more preferably 1% by weight or more.

＜Preparation of polishing composition＞ The polishing composition used in the technology disclosed herein may be a one-part form or a two-part multi-part form. For example, among the constituent components of the polishing composition, the part A containing at least the abrasive grains and the part B containing at least a part of the remaining ingredients are mixed, and these are mixed and diluted at an appropriate time when necessary, Prepared by polishing liquid.

The preparation method of the polishing composition is not particularly limited. For example, a well-known mixing device such as a wing mixer, an ultrasonic dispersion machine, or a homogenizer may be used to mix the components constituting the polishing composition. The aspect of mixing these components is not particularly limited. For example, all components may be mixed at once, or they may be mixed in an appropriately set order.

＜Use＞ The polishing composition disclosed here can be applied to polishing objects of various materials and shapes. The material of the object to be polished includes, for example, metals or semi-metals such as silicon, aluminum, nickel, tungsten, copper, tantalum, titanium, stainless steel, or these alloys; quartz glass, aluminosilicate glass, glassy carbon, etc. The glassy substance; ceramic materials such as alumina, silicon dioxide, sapphire, silicon nitride, tantalum nitride, titanium carbide, etc.; compound semiconductor substrate materials such as silicon carbide, gallium nitride, gallium arsenide, etc.; polyimide Resin materials such as resin; etc. Among these, it may be a polishing object composed of a plurality of materials. The shape of the object to be polished is not particularly limited. The polishing composition disclosed herein can be applied to polishing a polishing object having a flat surface such as a plate or polyhedron, or polishing the end of the polishing object (for example, polishing the edge of a wafer).

The polishing composition disclosed here is particularly useful for polishing surfaces made of silicon (typically polishing silicon wafers). A typical example of the so-called silicon wafer is a single crystal silicon wafer, for example, a single crystal silicon wafer obtained by thin-cutting a single crystal silicon ingot (ingot).

The polishing composition disclosed here is preferably suitable for polishing an object to be polished (for example, a silicon wafer). Before the polishing step by the polishing composition disclosed herein, the polishing object may be subjected to a general treatment that can be used for polishing objects in a step upstream of the polishing step such as polishing or etching.

The polishing composition disclosed herein is more effective for the final step of polishing an object (such as a silicon wafer) or the previous polishing step, and is particularly preferably used in the final polishing step. Here, the final polishing step refers to the final polishing step of the manufacturing process of the target object (that is, the step of not performing polishing after this step). The polishing composition disclosed herein can also be used in a polishing step upstream of the final polishing (referring to the preliminary polishing step between the rough polishing step and the final polishing step. Typically, it includes at least one polishing step, and may further include 2 times, 3 times･･･, etc. polishing steps), such as the polishing step performed before the final polishing.

The polishing composition disclosed here, for example, is more effective for polishing silicon wafers with a surface roughness of 0.01nm~100nm prepared by an upstream step (typically. Final polishing or previous polishing) . Especially good for final polishing. The surface roughness Ra of the polishing object can be measured using, for example, a laser scanning surface roughness meter "TMS-3000WRC" manufactured by Schmitt Measurement System Inc.

＜Grinding＞ The polishing composition disclosed here can be used for polishing an object to be polished, for example, in a state including the following operations. Hereinafter, a preferred aspect of a method of polishing a silicon wafer as a polishing object using the polishing composition disclosed herein will be described. That is, a polishing liquid containing any one of the polishing compositions disclosed herein is prepared. The above-mentioned polishing liquid is prepared, and the polishing liquid can be prepared by adding operations such as concentration adjustment (for example, dilution), pH adjustment, etc., to the polishing composition. Or, the polishing composition can be used directly as a polishing liquid.

Next, the polishing liquid is supplied to the object to be polished, and polishing is performed by a conventional method. For example, in the final polishing of a silicon wafer, typically, the silicon wafer that has undergone the polishing step is set in a general polishing device, and the polishing liquid is supplied to the polishing target surface of the silicon wafer through the polishing pad of the polishing device. Typically, the above-mentioned polishing liquid is continuously supplied, and the polishing pad is pressed against the polishing target surface of the silicon wafer to move the two relative to each other (for example, rotational movement). After this polishing step, the polishing of the object to be polished is completed.

The polishing pad used in the above-mentioned polishing step is not particularly limited. For example, polishing pads of foamed polyurethane type, non-woven fabric type, suede type, etc. can be used. Each polishing pad may or may not contain abrasive grains. Generally, it is preferable to use a polishing pad that does not contain abrasive grains.

The polishing object polished using the polishing composition disclosed here is typically washed. An appropriate detergent can be used for washing. The cleaning solution used is not particularly limited. For example, it can be used in the field of semiconductors and the like. General SC-1 cleaning solutions (ammonium hydroxide (NH ₄ OH) and hydrogen peroxide (H ₂ O ₂ )) and water ( Mixture of H ₂ O), SC-2 cleaning solution (mixture of hydrochloric acid (HCl) and H ₂ O ₂ and H ₂ O), etc. The temperature of the cleaning solution can be, for example, room temperature (typically about 15°C to 25°C) or higher to about 90°C. From the viewpoint of improving the cleaning effect, it is preferable to use a cleaning solution of about 50°C to 85°C.

As mentioned above, the technology disclosed herein may include providing a method of manufacturing a polishing object (for example, a method of manufacturing a silicon wafer) containing a polishing step (preferably final polishing) by any of the above-mentioned polishing methods and borrowing Polished objects (such as silicon wafers) produced by this method.

[Example]

The following describes several embodiments related to the present invention, but the present invention is not intended to be limited to these embodiments. In addition, in the following description, "parts" and "%" are based on weight unless otherwise stated.

＜Preparation of polishing composition＞ (Examples 1 and 2) The abrasive grains, water-soluble copolymer, basic compound, and deionized water were mixed to prepare the polishing composition concentrate of each example. Use colloidal silica (average secondary particle size: 45nm) as abrasive grains, and use N- as water-soluble copolymer synthesized from monomer raw materials with copolymerization ratio (mole ratio) shown in Table 1 A block copolymer (PACMO-PVA) composed of acrylomorpholine units (ACMO units) and vinyl alcohol units (VA units) uses ammonia as a basic compound. The weight average molecular weight (Mw) of the copolymer used in each example is shown in Table 1. Dilute the obtained polishing composition concentrate with deionized water (DIW) to a volume ratio of 20 times. The concentration of the abrasive particles is 0.18%, the concentration of the water-soluble copolymer is 0.0088%, and the concentration of the basic compound is 0.005%. .

(Comparative example 1) As the water-soluble polymer, instead of PACMO-PVA, polypropylene morpholine (PACMO) having Mw shown in Table 1 was used. The rest was the same as in Example 1, and the polishing composition of this example was prepared.

(Comparative example 2) As the water-soluble polymer, instead of PACMO-PVA, polyvinyl alcohol (PVA) having Mw shown in Table 1 was used. The rest was the same as in Example 1, and the polishing composition of this example was prepared.

(Example 3~8) The abrasive grains, water-soluble copolymer, basic compound, surfactant, and deionized water were mixed to prepare the polishing composition concentrate of each example. Using colloidal silica as abrasive particles (average secondary particle size: 45nm), the water-soluble copolymer is synthesized from N-acrylic acid based monomer raw materials with the copolymerization ratio (mole ratio) shown in Table 2 A block copolymer (PACMO-PVA) composed of morpholine unit (ACMO unit) and vinyl alcohol unit (VA unit), using ammonia as a basic compound and ethylene oxide as a surfactant to add moles Polyoxyethylene decyl ether of 5 (C10EO5). The weight average molecular weight (Mw) of the copolymer used in each example is shown in Table 2. The obtained polishing composition concentrate was diluted with deionized water (DIW) to a volume ratio of 20 times, and the concentration of abrasive grains was 0.18%, the concentration of water-soluble copolymer was 0.0088%, and the concentration of basic compound was 0.005%. , A polishing composition with a surfactant concentration of 0.0002%.

(Comparative example 3) As the water-soluble polymer, instead of PACMO-PVA, polypropylene morpholine (PACMO) having Mw shown in Table 2 was used. The rest was the same as in Example 3, and the polishing composition of this example was prepared.

(Comparative Example 4) As the water-soluble polymer, instead of PACMO-PVA, polyvinyl alcohol (PVA) having Mw shown in Table 2 was used. The rest was the same as in Example 3, and the polishing composition of this example was prepared.

＜Silicon Wafer Grinding＞ Prepare a commercially available single crystal silicon wafer (conductivity type: P type, crystal orientation: <100>, no COP (Crystal Originated Particle: crystal defect)) with a diameter of 200 mm for the finishing polishing and etching of the polishing object by the following Grinding condition 1, pre-polished silicon wafer. Preliminary polishing is performed with a slurry containing 1.0% abrasive particles (colloidal silica with an average secondary particle size of 55nm) and 0.068% potassium hydroxide in deionized water.

[Grinding condition 1] Grinding device: Single-side grinding device type "PNX-322" manufactured by Okamoto Machine Tool Manufacturing Co., Ltd. Grinding load: 15kPa The rotation speed of the platform: 30rpm Rotation speed of grinding head (carrying body): 30rpm Polishing pad: Fujibo Ehime Co., Ltd. product name "FP55" Supply speed of preparation slurry: 550mL/min The temperature of the preparation slurry: 20℃ Temperature of platform cooling water: 20℃ Grinding time: 3min

The polishing composition of each example prepared above was used as a polishing liquid, and the pre-polished silicon wafer was polished under the following polishing condition 2.

[Grinding condition 2] Grinding device: Single-sided grinding device type "PNX-322" manufactured by Okamoto Machine Tool Manufacturing Co., Ltd. Grinding load: 15kPa The rotation speed of the platform: 30rpm Rotation speed of grinding head (carrying body): 30rpm Polishing pad: manufactured by Fujibo Ehime Co., Ltd. Product name "POLYPAS27NX" Supply speed of polishing liquid: 400mL/min The temperature of the grinding fluid: 20℃ Temperature of platform cooling water: 20℃ Grinding time: 4min

Remove the polished silicon wafer from the polishing device _{and clean it with a cleaning solution of NH 4} OH (29%): H ₂ O ₂ (31%): deionized water = 1:1:12 (volume ratio) (SC-1 wash). Specifically, the first and second two washing tanks were prepared, and each of the washing tanks contained the above-mentioned washing liquid and kept at 60°C. The polished silicon wafer is immersed in the first washing tank for 5 minutes, then immersed in ultra-pure water, passed through a washing tank provided with ultrasonic waves, and immersed in the second washing tank for 5 minutes, and then immersed in ultra-pure water. After passing through a washing tank provided with ultrasonic waves, it is dried using a spin dryer (Spin Dryer).

<Haze measurement> For the surface of the cleaned silicon wafer, a wafer inspection device manufactured by KLA-Tencor, with the trade name "Surfscan SP2 ^XP ", was used to measure the haze (ppm) in the DWO mode. The obtained result is converted into a relative value (haze ratio) where the haze value of Comparative Example 2 is 100%, and is shown in Table 1 and Table 2. When the haze ratio is less than 100%, the haze improvement effect can be confirmed. The smaller the value of the haze ratio, the higher the haze improvement effect.

As shown in Table 1, the polishing composition of Examples 1 and 2 using PACMO-PVA as a water-soluble copolymer is compared with the polishing composition of Comparative Example 2 using PVA as a water-soluble polymer. The degree ratio becomes smaller, and the haze improvement effect becomes higher. From the above results, it is known that the water-soluble copolymer is a copolymer with N-(meth)acrylomorpholine units and vinyl alcohol units based on grinding grains, water-soluble copolymers, basic compounds, and water. When the composition is used, the surface quality of the polishing object after polishing can be improved.

As shown in Table 2, the polishing composition of Examples 3 to 8 using PACMO-PVA as a water-soluble copolymer is compared with the polishing composition of Comparative Example 4 using PVA as a water-soluble polymer. The degree ratio becomes smaller, and the haze improvement effect becomes higher. In the above examples, it was confirmed that the haze ratio becomes smaller as the ratio of ACMO units is higher, and the haze tends to be improved. Example 7 is the most excellent result. In addition, the haze ratio of Comparative Example 3 using only PACMO, which is a water-soluble polymer, was larger than that of Comparative Example 4 using PVA alone, and the haze improving effect was poor. From the above results, it is known that by including abrasive grains, water-soluble copolymer, basic compound, surfactant and water, and the water-soluble copolymer has N-(meth)acryloylmorpholine unit and vinyl alcohol The polishing composition of the copolymer of the unit can also improve the surface quality of the polishing object after polishing.

In the above, specific examples of the present invention have been described in detail, but these are only examples and do not limit the scope of the patent application. The technology described in the scope of the patent application includes various modifications and changes to the specific examples exemplified above.

Claims (6)

A polishing composition, which contains abrasive grains, a water-soluble copolymer, a basic compound and water, The aforementioned water-soluble copolymer is a copolymer having an N-(meth)acryloylmorpholine unit and a vinyl alcohol unit. The polishing composition of claim 1, wherein the weight average molecular weight of the water-soluble copolymer is 1×10 ⁴ or more. The polishing composition of claim 1 or 2, wherein the abrasive particles are silica particles. Such as the polishing composition of any one of claims 1 to 3, which further contains a surfactant or a water-soluble polymer. The polishing composition according to claim 4, wherein the aforementioned surfactant or water-soluble polymer contains a polyoxyalkylene structure-containing surfactant or an oxyalkylene-based polymer. For example, the polishing composition of any one of claims 1 to 5 is used in the final polishing step of the silicon wafer.