Polishing composition

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

[Technical Field]

[0001] The present invention relates to a polishing composition. This application claims priority to Japanese Patent Application No. 2020-044111, filed on March 13, 2020, the entire contents of which are incorporated herein by reference. [Background technology]

[0002] Precision polishing using a polishing composition is performed on the surfaces of materials such as metals, semi-metals, non-metals, and their oxides. For example, the surface of a silicon wafer, which is used as a component of a semiconductor device, is generally finished to a high-quality mirror surface through a lapping step (rough polishing step) and a polishing step (precise polishing step). The polishing step typically includes a pre-polishing step (preliminary polishing step) and a finish polishing step (final polishing step). Patent documents 1 and 2 are cited as technical documents related to polishing compositions used for polishing semiconductor substrates such as silicon wafers. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2018 / 043504 [Patent Document 2] Japanese Patent No. 6133271 Summary of the Invention [Problem to be solved by the invention]

[0004] Polishing compositions used for polishing semiconductor substrates such as silicon wafers and other substrates are required to achieve high-quality surfaces after polishing. In addition to abrasive grains and water, polishing compositions for such applications may contain water-soluble polymers for purposes such as protecting the surface of the object to be polished and improving wettability. The water-soluble polymers contribute to reducing defects and haze on the polished surface by adsorbing to and desorbing from the abrasive grains and the object to be polished. For example, Patent Document 1 discusses the use of graft copolymers with polyvinyl alcohol as the main chain and polyethylene oxide as the side chain, and random copolymers of vinyl alcohol and N-vinylpyrrolidone as the water-soluble polymers. Patent Document 2 uses graft copolymers of vinyl alcohol and N-vinylpyrrolidone.

[0005] Furthermore, in the above-mentioned substrate polishing, for example, in the finish polishing step (particularly in the finish polishing step of semiconductor substrates such as silicon wafers and other substrates), a polished surface of higher quality is required, and it would be practically useful to provide a polishing composition that can efficiently realize a substrate surface with lower haze. Therefore, an object of the present invention is to provide a polishing composition that can improve the surface quality of the polished object after polishing. [Means for solving the problem]

[0006] The polishing composition provided by this specification contains abrasive grains, a water-soluble copolymer, a basic compound, and water. The water-soluble copolymer is a copolymer having N-(meth)acryloylmorpholine units and vinyl alcohol units. A polishing composition having the above composition can improve the surface quality of an object to be polished after polishing. For example, haze can be reduced.

[0007] In this specification, the term "N-(meth)acryloylmorpholine unit" (hereinafter also referred to as "ACMO unit") refers to a structural portion corresponding to the structure generated by polymerization of the (meth)acryloyl group of N-(meth)acryloylmorpholine, and can also be referred to as a repeating unit (structural unit) derived from N-(meth)acryloylmorpholine. Furthermore, the term "vinyl alcohol unit" (hereinafter also referred to as "VA unit") refers to a structural portion represented by the following chemical formula: -CH-CH(OH)-.

[0008] The water-soluble copolymer has a weight average molecular weight of 1×10 4 A polishing composition containing the copolymer having the above weight average molecular weight (Mw) can more suitably exhibit the effect of improving haze.

[0009] Silica particles are preferably used as the abrasive grains. The haze-improving effect of the copolymer is particularly effective in polishing using silica particles as the abrasive grains.

[0010] In some embodiments, the polishing composition further comprises a surfactant or a water-soluble polymer. By using a polishing composition containing the copolymer described above and a surfactant or a water-soluble polymer, the haze on the surface of the object to be polished after polishing can be more effectively reduced.

[0011] In some preferred embodiments, the polishing composition contains a surfactant or an oxyalkylene polymer containing a polyoxyalkylene structure as the surfactant or the water-soluble polymer. By using a polishing composition having such a composition, haze can be more effectively improved.

[0012] The polishing composition disclosed herein can be preferably used in the finish polishing step of silicon wafers. By performing finish polishing using the polishing composition, haze can be improved and a high-quality silicon wafer surface can be suitably achieved. DETAILED DESCRIPTION OF THE INVENTION

[0013] Preferred embodiments of the present invention will be described below. It should be noted that matters necessary for carrying out the present invention other than those specifically mentioned in this specification can be understood as design matters for a person skilled in the art based on the prior art in the relevant field. The present invention can be carried out based on the contents disclosed in this specification and the common general technical knowledge in the relevant field.

[0014] <Polishing composition> (abrasive grain) The polishing composition disclosed herein contains abrasive grains. The abrasive grains mechanically polish the surface of the object to be polished. The material and properties of the abrasive grains are not particularly limited and can be appropriately selected depending on the intended use and manner of use of the polishing composition. Examples of abrasive grains include inorganic particles, organic particles, and organic-inorganic composite particles. Specific examples of inorganic particles include oxide particles such as silica particles, alumina particles, cerium oxide particles, chromium oxide particles, titanium dioxide particles, zirconium oxide particles, magnesium oxide particles, manganese dioxide particles, zinc oxide particles, and red iron oxide particles; nitride particles such as silicon nitride particles and boron nitride particles; carbide particles such as silicon carbide particles and boron carbide particles; diamond particles; and carbonates such as calcium carbonate and barium carbonate. Specific examples of organic particles include polymethyl methacrylate (PMMA) particles, poly(meth)acrylic acid particles (here, (meth)acrylic acid refers collectively to acrylic acid and / or methacrylic acid), and polyacrylonitrile particles. Such abrasive grains may be used alone or in combination of two or more kinds.

[0015] The abrasive grains are preferably inorganic particles, and among these, particles made of metal or semi-metal oxides are preferred, with silica particles being particularly preferred. For example, in a polishing composition that can be used for polishing (e.g., finish polishing) an object to be polished having a silicon surface, such as a silicon wafer, as described below, it is particularly meaningful to employ silica particles as the abrasive grains. The technology disclosed herein can be preferably implemented, for example, in an embodiment in which the abrasive grains are essentially made of silica 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 grains are silica particles.

[0016] Specific examples of silica particles include colloidal silica, fumed silica, precipitated silica, etc. Silica particles can be used alone or in combination of two or more types. Colloidal silica is particularly preferred because it is easy to obtain a polished surface with excellent surface quality after polishing. As colloidal silica, for example, colloidal silica produced by an ion exchange method using water glass (sodium silicate) as a raw material, or alkoxide method colloidal silica (colloidal silica produced by the hydrolysis and condensation reaction of alkoxysilane) can be preferably used. Colloidal silica can be used alone or in combination of two or more types.

[0017] The true specific gravity of the abrasive grain material (e.g., silica constituting silica particles) is preferably 1.5 or more, more preferably 1.6 or more, and even more preferably 1.7 or more. The upper limit of the true specific gravity of silica 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 the abrasive grain (e.g., silica particles) can be measured by a liquid displacement method using ethanol as the displacement liquid.

[0018] The average primary particle diameter of the abrasive grains (e.g., silica particles) is not particularly limited, and from the viewpoint of polishing rate, etc., it is preferably 5 nm or more, more preferably 10 nm or more. From the viewpoint of obtaining a higher polishing effect (e.g., effects such as haze reduction and defect removal), the average primary particle diameter is preferably 15 nm or more, more preferably 20 nm or more (e.g., more than 20 nm). Furthermore, from the viewpoint of scratch prevention, etc., the average primary particle diameter of the abrasive grains is preferably 100 nm or less, more preferably 50 nm or less, and even more preferably 40 nm or less. From the viewpoint of making it easier to obtain a surface with lower haze, in some embodiments, the average primary particle diameter of the abrasive grains may be 35 nm or less, or may be less than 32 nm, or may be less than 30 nm.

[0019] In this specification, the average primary particle size is calculated from the specific surface area (BET value) measured by the BET method as follows: average primary particle size (nm) = 6000 / (true density (g / cm 3 )×BET value(m 2 / g) The specific surface area can be measured using, for example, a surface area measuring device manufactured by Micromeritics, under the trade name "Flow Sorb II 2300."

[0020] The average secondary particle diameter of the abrasive grains (e.g., silica particles) is not particularly limited and can be appropriately selected, for example, from a range of about 15 nm to 300 nm. From the viewpoint of improving polishing efficiency, the average secondary particle diameter is preferably 30 nm or more, more preferably 35 nm or more. In some embodiments, the average secondary particle diameter may be, for example, 40 nm or more, 42 nm or more, or preferably 44 nm or more. Furthermore, the average secondary particle diameter is usually advantageously 250 nm or less, preferably 200 nm or less, and more preferably 150 nm or less. In some preferred embodiments, the average secondary particle diameter is 120 nm or less, more preferably 100 nm or less, even more preferably 70 nm or less, for example, 60 nm or less, or even 50 nm or less.

[0021] In this specification, the average secondary particle size refers to the particle size (volume average particle size) measured by dynamic light scattering. The average secondary particle size of the abrasive grains can be measured by dynamic light scattering using, for example, "Nanotrac (registered trademark) UPA-UT151" manufactured by Nikkiso Co., Ltd.

[0022] The shape (external shape) of the abrasive grains may be spherical or non-spherical. Specific examples of non-spherical particles include peanut-shaped (i.e., peanut shell-shaped), cocoon-shaped, confetti-shaped, and rugby ball-shaped. For example, abrasive grains in which most of the particles are peanut-shaped or cocoon-shaped can be preferably used.

[0023] Although not particularly limited, the average value of the long diameter / short diameter ratio (average aspect ratio) of the abrasive grains is, in principle, 1.0 or more, preferably 1.05 or more, and more preferably 1.1 or more. By increasing the average aspect ratio, a higher polishing rate can be achieved. Furthermore, from the viewpoint of reducing scratches, the average aspect ratio of the abrasive grains is preferably 3.0 or less, more preferably 2.0 or less, and even more preferably 1.5 or less.

[0024] The shape (outline) and average aspect ratio of abrasive grains can be determined, for example, by observation using an electron microscope. A specific procedure for determining the average aspect ratio involves, for example, using a scanning electron microscope (SEM), drawing the smallest rectangle circumscribing each particle image for a predetermined number (e.g., 200) of abrasive grains whose individual particle shapes can be recognized. Then, for each rectangle drawn for each particle image, the long side length (long diameter value) is divided by the short side length (short diameter value) to calculate the long diameter / short diameter ratio (aspect ratio). The average aspect ratio can be determined by arithmetically averaging the aspect ratios of the predetermined number of particles.

[0025] The content of abrasive grains in the polishing composition is not particularly limited, and is, for example, 0.01% by weight or more, preferably 0.05% by weight or more, more preferably 0.10% by weight or more, and even more preferably 0.15% by weight or more. By increasing the content of abrasive grains, a higher polishing rate can be achieved. The content is suitably 10% by weight or less, preferably 7% by weight or less, more preferably 5% by weight or less, and even more preferably 2% by weight or less, and may be, for example, 1% by weight or less, or 0.5% by weight or less. This allows for a surface with lower haze. The above content of abrasive grains can be preferably adopted in an embodiment in which the polishing composition is used in the form of a polishing liquid.

[0026] (Water-soluble copolymer) The polishing composition disclosed herein contains a water-soluble copolymer having N-(meth)acryloylmorpholine units (ACMO units) and vinyl alcohol units (VA units). Polishing using this water-soluble copolymer improves the surface quality of the polished object after polishing. The reason for this is that the water-soluble copolymer has two units with different chemical structures that exhibit different effects (adsorption) on abrasive grains and the object to be polished. The water-soluble copolymer molecule exhibits appropriate adsorption to abrasive grains and the object to be polished, which is thought to significantly contribute to improving the surface quality of the object to be polished after polishing. However, the effects of the water-soluble copolymer disclosed herein are not limited to the above interpretation.

[0027] The proportion of ACMO units in the copolymer can be 1 mol% or more, and is suitably 5 mol% or more, from the viewpoint of exhibiting the effects of containing ACMO units. In some embodiments, the proportion of ACMO units in the copolymer is preferably 10 mol% or more, more preferably 20 mol% or more, and even more preferably 30 mol% or more (e.g., 40 mol% or more), from the viewpoint of effectively exhibiting the effects of containing ACMO units. In some preferred embodiments, the proportion of ACMO units in the copolymer is 50 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, and particularly preferably 85 mol% or more, from the viewpoint of obtaining a more excellent haze improvement effect. By increasing the proportion of ACMO units, the polishing composition can impart good etching resistance to wafers. The upper limit of the proportion of ACMO units in the copolymer is suitably 99 mol% or less, and is suitably 97 mol% or less, more preferably 95 mol% or less, even more preferably 92 mol% or less, and particularly preferably 90 mol% or less, from the viewpoint of exhibiting the effects of structural units other than ACMO units, such as VA units. In some embodiments, the proportion of ACMO units in the copolymer may be 80 mol % or less, 65 mol % or less, 45 mol % or less, or 25 mol % or less.

[0028] The proportion of VA units in the copolymer can be 0.1 mol% or more, and is suitably 1 mol% or more, from the viewpoint of achieving the effect of containing VA units. In some embodiments, the proportion of VA units in the copolymer is preferably 2 mol% or more, more preferably 3 mol% or more, even more preferably 5 mol% or more, and particularly preferably 8 mol% or more (e.g., 10 mol% or more), from the viewpoint of achieving a more excellent haze improvement effect. In some embodiments, the proportion of VA units in the copolymer may be 20 mol% or more, 40 mol% or more, 60 mol% or more, or even 80 mol% or more. The upper limit of the proportion of VA units in the copolymer may be 95 mol% or less, 80 mol% or less, 60 mol% or less, 50 mol% or less, or 40 mol% or less, from the viewpoint of achieving the effect of structural units other than VA units, such as ACMO units. In some preferred embodiments, the proportion of VA units in the copolymer is 30 mol % or less, more preferably 20 mol % or less, even more preferably 15 mol % or less, and may be 10 mol % or less, from the viewpoint of obtaining an excellent haze improvement effect.

[0029] In this specification, the proportion (mol %) of structural units such as ACMO units and VA units constituting the water-soluble copolymer refers to the proportion of the number of moles of each structural unit to the number of moles of all repeating units (monomer units) constituting one molecule of the water-soluble copolymer.

[0030] In the water-soluble copolymer disclosed herein, the ratio of ACMO units to VA units is not limited to a specific range, as it can be appropriately set so that the functions of each structural unit are fully exhibited. The molar ratio of ACMO units to VA units (ACMO:VA) in the water-soluble copolymer can be 1:99 or more. To effectively exhibit the effects of containing ACMO units, the molar ratio (ACMO:VA) is preferably 5:95 or more, more preferably 10:90 or more, even more preferably 20:80 or more, and particularly preferably 30:70 or more (e.g., 40:60 or more). In some preferred embodiments, the molar ratio (ACMO:VA) is 50:50 or more, more preferably 70:30 or more, even more preferably 80:20 or more, and particularly preferably 85:15 or more, to obtain a more excellent haze improvement effect. By increasing the proportion of ACMO units, the polishing composition can impart good etching resistance to wafers. The upper limit of the molar ratio (ACMO:VA) can be 99.9:0.1 or less, suitably 99:1 or less, preferably 97:3 or less, more preferably 95:5 or less, even more preferably 92:8 or less, and particularly preferably 90:10 or less. In some embodiments, the molar ratio (ACMO:VA) may be 80:20 or less, 65:35 or less, 45:55 or less, or 25:75 or less.

[0031] The total proportion of ACMO units and VA units constituting the water-soluble copolymer disclosed herein is suitably 50 mol% or more (e.g., more than 50 mol%), preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, and particularly preferably 95 mol% or more (e.g., 99 to 100 mol%), from the viewpoint of effectively achieving the effects of including ACMO units and VA units.

[0032] The water-soluble copolymer disclosed herein may have, in addition to ACMO units and VA units, structural units derived from other monomers copolymerizable therewith. The other monomers are not particularly limited, and examples thereof include (meth)acrylic acid alkyl esters such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate; alkylene glycol (meth)acrylates such as (poly)ethylene glycol mono(meth)acrylate and (poly)propylene glycol mono(meth)acrylate; unsaturated acids and alkyl esters thereof such as (meth)acrylic acid, crotonic acid, maleic acid, itaconic acid, and fumaric acid; unsaturated acid anhydrides such as maleic anhydride; sulfonic acid group-containing monomers such as 2-acrylamido-2-methylpropanesulfonic acid and salts thereof; N-alkyl(meth)acrylamides such as methyl(meth)acrylamide, ethyl(meth)acrylamide, n-propyl(meth)acrylamide, isopropyl(meth)acrylamide, n-butyl(meth)acrylamide, and 2-ethylhexyl(meth)acrylamide; methylaminopropyl(meth)acrylamide; (Di)alkylaminoalkylamides such as methylaminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, ethylaminoethyl (meth)acrylate, and diethylaminopropyl (meth)acrylamide; (Di)alkylaminoalkyl (meth)acrylates such as methylaminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, ethylaminoethyl (meth)acrylate, and diethylaminoethyl (meth)acrylate; N-vinyl lactam monomers such as N-vinylpyrrolidone, N-vinylpiperidone, N-vinylmorpholinone, N-vinylcaprolactam, N-vinyl-1,3-oxazin-2-one, and N-vinyl-3,5-morpholinedione; N-vinyl linear amides such as N-vinylacetamide, N-vinylpropionic acid amide, and N-vinylbutyric acid amide; cyclic amides having an N-(meth)acryloyl group other than ACMO, such as N-(meth)acryloylpyrrolidine; aromatic vinyl compounds such as styrene, vinyltoluene, and vinylxylene;Examples of suitable vinyl ethers include alkyl vinyl ethers having an alkyl group having 1 to 10 carbon atoms, such as 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, and n-decyl vinyl ether; vinyl ester compounds such as vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl piperate, and vinyl versatate; and α-olefins such as ethylene, propylene, and butylene, and one or more of these may be used.

[0033] The amount of other monomers used in the water-soluble copolymer can be 50 mol% or less (e.g., less than 50 mol%), for example, 30 mol% or less, preferably 20 mol% or less, more preferably 10 mol% or less, and even more preferably 5 mol% or less (e.g., 0 to 1 mol%).

[0034] The copolymerization form of the water-soluble copolymer disclosed herein is not particularly limited, and the water-soluble copolymer may be in any form, such as a block copolymer having ACMO units and VA units, a graft copolymer, a random copolymer, or an alternating copolymer, but is preferably a block copolymer.

[0035] In some preferred embodiments, the water-soluble copolymer is a copolymer containing a PACMO (poly-N-(meth)acryloylmorpholine) segment having ACMO units as the main repeating units (main structural units) and a PVA (polyvinyl alcohol) segment having VA units as the main repeating units (main structural units). In this specification, the term "main repeating unit" refers to the repeating unit (structural unit) that occupies the largest proportion, in terms of molar number, of all repeating units (monomer units) constituting the segment, unless otherwise specified.

[0036] The water-soluble copolymer having a PACMO segment and a PVA segment has a structure containing at least one PACMO segment and at least one PVA segment in the same molecule. The water-soluble copolymer may be, for example, a random copolymer, block copolymer, or graft copolymer containing a PACMO segment and a PVA segment. The structure of the block copolymer is not particularly limited and may be a diblock copolymer, a triblock copolymer, a radial copolymer, a mixture thereof, or the like. From the viewpoint of optimally exhibiting the function of each segment, the water-soluble copolymer preferably contains a diblock copolymer. The structure of the graft copolymer is also not particularly limited and may be, for example, a graft copolymer having a structure in which a PVA segment (side chain) is grafted onto a PACMO segment (main chain), or a graft copolymer having a structure in which a PACMO segment (side chain) is grafted onto a PVA segment (main chain).

[0037] [PACMO Segment] The PACMO segment may contain only ACMO units as repeating units, or may contain ACMO units and non-ACMO units, which are repeating units derived from monomers other than ACMO. In embodiments where the PACMO segment contains non-ACMO units, the non-ACMO units may be repeating units having at least one structure selected from, for example, an oxyalkylene group, a carboxy group, a sulfo group, an amino group, a hydroxyl group, an amide group, an imide group, a nitrile group, an ether group, an ester group, and salts thereof. The PACMO segment may contain only one type of non-ACMO unit, or two or more types of non-ACMO units. Examples of non-ACMO units that can be contained in the PACMO segment include the above-mentioned structural units derived from other monomers copolymerizable with the ACMO unit and the VA unit, and VA units.

[0038] The proportion of moles of ACMO units to the total number of moles of repeating units constituting the PACMO segment is, for example, 50% or more (e.g., more than 50%), suitably 70% or more, and preferably 80% or more. In some preferred embodiments, the proportion of moles of ACMO units to the total number of moles of repeating units constituting the PACMO segment may be, for example, 90% or more, 95% or more, or even 98% or more. Substantially 100% of the repeating units constituting the PACMO segment may be ACMO units. Here, "substantially 100%" means that, at least intentionally, the PACMO segment does not contain non-ACMO units.

[0039] [PVA Segment] The PVA segment may contain only VA units as repeating units, or may contain VA units and non-VA units, which are repeating units other than VA units. In embodiments where the PVA segment contains non-VA units, the non-VA units may be repeating units having at least one structure selected from an oxyalkylene group, a carboxy group, a sulfo group, an amino group, a hydroxyl group, an amide group, an imide group, a nitrile group, an ether group, an ester group, and salts thereof. The PVA segment may contain only one type of non-VA unit, or two or more types of non-VA units. Examples of non-VA units that may be contained in the PVA segment include the above-mentioned ACMO units and structural units derived from other monomers copolymerizable with the VA units, as well as ACMO units.

[0040] The ratio of the number of moles of VA units to the number of moles of all repeating units constituting the PVA segment is, for example, 50% or more (e.g., more than 50%), suitably 70% or more, and preferably 80% or more. In some preferred embodiments, the ratio of the number of moles of VA units to the number of moles of all repeating units constituting the PVA segment may be, for example, 90% or more, 95% or more, or even 98% or more. Substantially 100% of the repeating units constituting the PVA segment may be VA units. Here, "substantially 100%" means that non-VA units are not contained in the PVA segment, at least intentionally.

[0041] Water-soluble copolymers can be obtained by known methods (specifically, various polymerization methods) or commercially available. For example, water-soluble copolymers having ACMO units and VA units can be formed by modifying a copolymer (random copolymer, block copolymer, or graft copolymer) of N-(meth)acryloylmorpholine with a monomer that can be converted to VA units (e.g., a vinyl ester compound such as vinyl acetate). For example, a copolymer containing ACMO units and VA units can be obtained by partially or completely saponifying a block copolymer of vinyl acetate and N-(meth)acryloylmorpholine.

[0042] The weight average molecular weight (Mw) of the water-soluble copolymer disclosed herein is not particularly limited, and may be, for example, 2×10 3 Can be more than 1 x 10 4 It may be 5.0 x 10 or more. 4 The above Mw is preferably 1.0 × 10 5 More preferably, 2.0 × 10 5 More preferably, 3.0 × 10 5 More preferably, 4.5 × 10 5 That's 4.5 x 10 5 The water-soluble copolymer disclosed herein can disperse abrasive grains well even if it has a relatively high molecular weight (for example, Mw of about 300,000 or more). The upper limit of the Mw is, for example, 10 × 10 5 is less than or equal to 8.0 x 10 5 From the viewpoint of the adsorption to the abrasive grains, the following is appropriate. 5 Less than 6.0 × 10, more preferably 5 is less than or equal to 5.0 x 10 5or less. In this specification, the weight-average molecular weight (Mw) and number-average molecular weight (Mn) of the water-soluble copolymer, other water-soluble polymers described later, and surfactants can be values ​​(converted to polymethyl methacrylate) based on gel permeation chromatography (GPC). As the GPC measuring device, it is recommended to use a model "HLC-8320GPC" manufactured by Tosoh Corporation. Measurements can be carried out, for example, under the following conditions. Similar methods are also used in the examples described later. [GPC measurement conditions] Sample concentration: 0.1% by weight Column: TSKgel SuperHM-M x 3 Detector: RI Eluent: N,N-dimethylformamide (containing 10 mM LiBr) Flow rate: 300μL / min Measurement temperature: 40℃ Sample injection volume: 200 μL

[0043] The content of the water-soluble copolymer in the polishing composition is not particularly limited, and may be, for example, 1.0×10 -4 From the viewpoint of reducing haze, the preferred content is 5.0 × 10 -4 % by weight or more, more preferably 1.0 × 10 -3 % by weight or more, more preferably 2.0 × 10 -3 % by weight or more. For example, 5.0 × 10 -3 % by weight or more, and -3 It may be % by weight or more. Furthermore, from the viewpoint of polishing rate, etc., the content is preferably 0.2% by weight or less, more preferably 0.1% by weight or less, even more preferably 0.05% by weight or less, and may be 0.02% by weight or less (for example, 0.01% by weight or less). When the polishing composition contains two or more water-soluble copolymers, the content refers to the total content (content by weight) of all water-soluble copolymers contained in the polishing composition. The water-soluble copolymer content can be preferably adopted in an embodiment in which the polishing composition is used in the form of a polishing liquid.

[0044] The content of the water-soluble copolymer (when two or more water-soluble copolymers are contained, the total amount thereof) can also be determined by the relative relationship with the abrasive grains. Although not particularly limited, in some embodiments, the content of the water-soluble copolymer per 100 parts by weight of the abrasive grains can be, for example, 0.01 parts by weight or more. From the viewpoint of haze reduction, etc., it is appropriate to set it to 0.1 parts by weight or more, preferably 0.5 parts by weight or more, more preferably 1 part by weight or more, even more preferably 3 parts by weight or more, for example, 4 parts by weight or more. Furthermore, the content of the water-soluble copolymer per 100 parts by weight of the abrasive grains may be, for example, 50 parts by weight or less, or may be 30 parts by weight or less. From the viewpoint of dispersion stability of the polishing composition, etc., in some embodiments, the content of the water-soluble copolymer per 100 parts by weight of the abrasive grains is appropriate to set it to 15 parts by weight or less, preferably 10 parts by weight or less, more preferably 8 parts by weight or less, or may be 7 parts by weight or less.

[0045] (basic compounds) The polishing composition disclosed herein contains a basic compound. In this specification, a basic compound refers to a compound that dissolves in water and increases the pH of the aqueous solution. Examples of basic compounds that can be used include nitrogen-containing organic or inorganic basic compounds, phosphorus-containing basic compounds, alkali metal hydroxides, alkaline earth metal hydroxides, and various carbonates and bicarbonates. Examples of nitrogen-containing basic compounds include quaternary ammonium compounds, ammonia, and amines (preferably water-soluble amines). Examples of phosphorus-containing basic compounds include quaternary phosphonium compounds. These basic compounds can be used alone or in combination.

[0046] Specific examples of alkali metal hydroxides include potassium hydroxide and sodium hydroxide. Specific examples of carbonates or bicarbonates include ammonium bicarbonate, ammonium carbonate, potassium bicarbonate, potassium carbonate, sodium bicarbonate, and sodium carbonate. Specific examples of amines include methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, ethylenediamine, monoethanolamine, N-(β-aminoethyl)ethanolamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, anhydrous piperazine, piperazine hexahydrate, 1-(2-aminoethyl)piperazine, N-methylpiperazine, guanidine, and azoles such as imidazole and triazole. Specific examples of quaternary phosphonium compounds include quaternary phosphonium hydroxides such as tetramethylphosphonium hydroxide and tetraethylphosphonium hydroxide.

[0047] As the quaternary ammonium compound, a quaternary ammonium salt (typically a strong base) such as a tetraalkylammonium salt or a hydroxyalkyltrialkylammonium salt can be used. The anion component in such a quaternary ammonium salt is, for example, OH - , F - , Cl - , Br - , I - , ClO4 - , BH4 - Examples of the quaternary ammonium compounds include those in which the anion is OH. - Specific examples of quaternary ammonium hydroxides include tetraalkylammonium hydroxides such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetrapentylammonium hydroxide, and tetrahexylammonium hydroxide; hydroxyalkyltrialkylammonium hydroxides such as 2-hydroxyethyltrimethylammonium hydroxide (also known as choline); and the like.

[0048] Among these basic compounds, at least one basic compound selected from, for example, alkali metal hydroxides, quaternary ammonium hydroxides, and ammonia can be preferably used. Among these, tetraalkylammonium hydroxides (e.g., tetramethylammonium hydroxide) and ammonia are more preferred, and ammonia is particularly preferred.

[0049] The concentration of the basic compound in the polishing composition disclosed herein is not particularly limited.From the viewpoint of polishing rate, etc., the concentration is suitably 0.0005 wt% or more, preferably 0.001 wt% or more.In addition, from the viewpoint of haze reduction, etc., the concentration is suitably less than 0.3 wt%, preferably less than 0.1 wt%, more preferably less than 0.05 wt% (for example, less than 0.025 wt%).The above basic compound concentration can be preferably adopted in an embodiment in which the polishing composition is used in the form of a polishing liquid.

[0050] (surfactant) The polishing composition disclosed herein can contain a surfactant, if necessary. By adding a surfactant to the polishing composition, haze on the surface of the object to be polished after polishing can be more effectively reduced. Any of anionic, cationic, nonionic, and amphoteric surfactants can be used as the surfactant. Anionic or nonionic surfactants are preferably used. Nonionic surfactants are more preferred from the viewpoints of low foaming and ease of pH adjustment. Examples of nonionic surfactants include oxyalkylene polymers such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol; polyoxyalkylene derivatives (e.g., polyoxyalkylene adducts) such as polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene alkylamines, polyoxyethylene fatty acid esters, polyoxyethylene glyceryl ether fatty acid esters, and polyoxyethylene sorbitan fatty acid esters; and copolymers of multiple oxyalkylenes (e.g., diblock copolymers, triblock copolymers, random copolymers, and alternating copolymers). The surfactant preferably includes a surfactant containing a polyoxyalkylene structure. The surfactants can be used alone or in combination of two or more.

[0051] Specific examples of nonionic surfactants containing a polyoxyalkylene structure include block copolymers of ethylene oxide (EO) and propylene oxide (PO) (diblock copolymers, PEO (polyethylene oxide)-PPO (polypropylene oxide)-PEO type triblock copolymers, PPO-PEO-PPO type triblock copolymers, etc.), random copolymers 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 ... 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 propyl ether, polyoxyethylene butyl ether, polyoxyethylene pentyl ether, polyoxyethylene Examples of the hydroxypropyl methylcellulose include polyoxyethylene oleyl ether, polyoxyethylene phenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene nonylphenyl ether, polyoxyethylene dodecylphenyl ether, polyoxyethylene styrenated phenyl ether, polyoxyethylene laurylamine, polyoxyethylene stearylamine, polyoxyethylene oleylamine, polyoxyethylene monolaurate, polyoxyethylene monostearate, polyoxyethylene distearate, polyoxyethylene monooleate, polyoxyethylene dioleate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopaltimate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan trioleate, polyoxyethylene sorbitan tetraoleate, polyoxyethylene castor oil, and polyoxyethylene hydrogenated castor oil.Among these, preferred surfactants include block copolymers of EO and PO (particularly PEO-PPO-PEO type triblock copolymers), random copolymers of EO and PO, and polyoxyethylene alkyl ethers (for example, polyoxyethylene decyl ether).

[0052] The molecular weight of the surfactant is typically less than 2000, and preferably less than 1900 (for example, less than 1800) from the viewpoints of filterability and washability. Furthermore, the molecular weight of the surfactant is suitably 200 or more from the viewpoint of surface activity, and preferably 250 or more (for example, 300 or more) from the viewpoint of haze reduction effect. A more preferable range of the molecular weight of the surfactant may vary depending on the type of surfactant. For example, when a polyoxyethylene alkyl ether is used as the surfactant, its molecular weight is preferably 1500 or less, and may be 1000 or less (for example, 500 or less). Furthermore, when a PEO-PPO-PEO triblock copolymer is used as the surfactant, its molecular weight may be, for example, 500 or more, 1000 or more, or even 1200 or more. The molecular weight of the surfactant can be the weight-average molecular weight (Mw) determined by GPC or the molecular weight calculated from the chemical formula.

[0053] When the polishing composition disclosed herein contains a surfactant, its content is not particularly limited as long as it does not significantly impair the effects of the present invention. From the viewpoint of cleaning properties, etc., the content of the surfactant per 100 parts by weight of abrasive grains 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 or less). From the viewpoint of better exerting the effect of using the surfactant, the content of the surfactant per 100 parts by weight of abrasive grains is suitably 0.001 parts by weight or more, preferably 0.005 parts by weight or more, and may be 0.01 parts by weight or more or 0.05 parts by weight or more.

[0054] When the polishing composition disclosed herein contains a surfactant, the content W of the water-soluble copolymer A and surfactant content WB Weight ratio (W A / W B ) is not particularly limited and can be, for example, in the range of 0.01 to 200, preferably in the range of 0.05 to 100, and more preferably in the range of 0.1 to 80. Alternatively, from the viewpoint of simplifying the composition, the polishing composition disclosed herein can also be preferably implemented in an embodiment that is substantially free of surfactants.

[0055] (water) The water contained in the polishing composition disclosed herein can preferably be ion-exchanged water (deionized water), pure water, ultrapure water, distilled water, etc. In order to minimize the inhibition of the functions of other components contained in the polishing composition, the water used preferably has a total transition metal ion content of, for example, 100 ppb or less. For example, the purity of the water can be increased by removing impurity ions using an ion exchange resin, removing foreign matter using a filter, distillation, or other procedures.

[0056] (Other water-soluble polymers) The polishing composition disclosed herein may further contain other water-soluble polymers, i.e., water-soluble polymers other than the above-mentioned water-soluble copolymers, as needed, provided that the effects of the present invention are not significantly impaired. The other water-soluble polymers can be appropriately selected from water-soluble polymers known in the field of polishing compositions. Examples of other water-soluble polymers include vinyl alcohol-based polymers, oxyalkylene-based polymers, N-vinyl polymers, and N-(meth)acryloyl-based polymers. Examples of vinyl alcohol-based polymers include polyvinyl alcohol (PVA) and modified PVA. Examples of oxyalkylene-based polymers include polymers containing oxyalkylene units, such as block copolymers of ethylene oxide (EO) and propylene oxide (PO). The N-vinyl-based polymer may be a homopolymer or copolymer of an N-vinyl-based monomer. Specific examples of N-vinyl-based polymers include a homopolymer of N-vinylpyrrolidone (VP) and a copolymer with a copolymerization ratio of VP of 70% by weight or more. The N-(meth)acryloyl-based polymer may be a homopolymer or copolymer of an N-(meth)acryloyl-based monomer. Specific examples of N-(meth)acryloyl type polymers include homopolymers of N-isopropylacrylamide (NIPAM), copolymers with a copolymerization ratio of NIPAM of 70% by weight or more, and homopolymers and copolymers of N-acryloylmorpholine (ACMO). Other water-soluble polymers include homopolymers and copolymers of N-acylalkyleneimine type monomers. In addition to the above synthetic polymers, other water-soluble polymers that can be used include cellulose derivatives such as hydroxyethyl cellulose and polymers derived from natural products such as starch derivatives. The above other water-soluble polymers can be used alone or in combination of two or more.

[0057] In the technology disclosed herein, the weight-average molecular weight (Mw) of the other water-soluble polymer is not particularly limited. The weight-average molecular weight (Mw) of the other water-soluble polymer is, for example, 100 × 10 4 It may be 60 × 10 or less from the viewpoint of cleaning properties, etc. 4The following is appropriate: 30 x 10 4 or less, preferably 20×10 4 For example, 10 x 10 4 May be less than 8 x 10 4 From the viewpoint of protecting the object to be polished, the Mw of the other water-soluble polymer may be, for example, 2000 or more, and preferably 5000 or more. In some embodiments, the Mw is 1.0 × 10 4 The above is appropriate, and 2 x 10 4 or more, for example, 5×10 4 More than that is fine.

[0058] From the viewpoint of reducing agglomerates and improving cleaning properties, a nonionic polymer can be preferably used as the other water-soluble polymer. Also, from the viewpoint of easy control of chemical structure and purity, a synthetic polymer can be preferably used as the other water-soluble polymer. The polishing composition disclosed herein can be preferably implemented in an embodiment in which a polymer derived from a natural product is not substantially used as the other water-soluble polymer.

[0059] In the embodiment of the polishing composition containing other water-soluble polymers, the content of other water-soluble polymers is usually less than 100 parts by weight per 100 parts by weight of the water-soluble copolymer, suitably less than 50 parts by weight, may be less than 30 parts by weight, may be less than 20 parts by weight, may be less than 10 parts by weight, may be less than 5 parts by weight.In addition, the content of other water-soluble polymers is 0.01 parts by weight or more per 100 parts by weight of the water-soluble copolymer, suitably 0.1 parts by weight or more, may be 1 part by weight or more, for example, may be 3 parts by weight or more.In addition, the technology disclosed herein can also be suitably implemented in an embodiment that does not substantially contain other water-soluble polymers. In addition, "substantially not used" or "substantially not contained" means that the amount used per 100 parts by weight of the water-soluble copolymer is typically 3 parts by weight or less, preferably 1 part by weight or less, and includes 0 parts by weight or below the detection limit.

[0060] (Other ingredients) The polishing composition disclosed herein may further contain, as necessary, known additives that can be used in polishing compositions (e.g., polishing compositions used in the finish polishing step of silicon wafers), such as chelating agents, organic acids, organic acid salts, inorganic acids, inorganic acid salts, preservatives, and antifungal agents, within the range that does not significantly impair the effects of the present invention.

[0061] The polishing composition disclosed herein is preferably substantially free of oxidizing agents. If an oxidizing agent is present in the polishing composition, for example, during polishing of a silicon wafer, the surface of the silicon wafer is oxidized to form an oxide film, thereby lengthening the required polishing time. Specific examples of oxidizing agents include hydrogen peroxide (HO), sodium persulfate, ammonium persulfate, and sodium dichloroisocyanurate. The term "substantially free of oxidizing agents" means that the polishing composition does not contain an oxidizing agent, at least intentionally. Therefore, a polishing composition that inevitably contains a trace amount of oxidizing agent due to raw materials, manufacturing method, etc. (e.g., a molar concentration of the oxidizing agent in the polishing composition of 0.0005 mol / L or less, preferably 0.0001 mol / L or less, more preferably 0.00001 mol / L or less, and particularly preferably 0.000001 mol / L or less) can be included in the concept of a polishing composition that is substantially free of oxidizing agents.

[0062] (pH) The pH of the polishing composition disclosed herein is suitably, for example, 8.0 or higher, preferably 8.5 or higher, more preferably 9.0 or higher. As the pH of the polishing composition increases, the polishing rate tends to improve. On the other hand, from the viewpoint of preventing dissolution of abrasive grains (e.g., silica particles) and suppressing a decrease in mechanical polishing action, the pH of the polishing composition is suitably 12.0 or lower, preferably 11.0 or lower, more preferably 10.8 or lower, and even more preferably 10.6 or lower, and may be, for example, 10.3 or lower.

[0063] The pH can be determined by using a pH meter (for example, a glass electrode hydrogen ion concentration indicator (model number F-23) manufactured by Horiba, Ltd.) and performing three-point calibration using standard buffer solutions (phthalate pH buffer solution, pH: 4.01 (25°C), neutral phosphate pH buffer solution, pH: 6.86 (25°C), carbonate pH buffer solution, pH: 10.01 (25°C)), then placing the glass electrode in the composition to be measured and measuring the value after stabilization for at least two minutes.

[0064] <Polishing liquid> The polishing composition disclosed herein is typically supplied to the surface of an object to be polished in the form of a polishing liquid containing the polishing composition and used to polish the object to be polished. The polishing liquid can be prepared, for example, by diluting any of the polishing compositions disclosed herein (typically with water). Alternatively, the polishing composition can be used as a polishing liquid as is. That is, the concept of the polishing composition in the technology disclosed herein includes both a polishing liquid (working slurry) that is supplied to an object to be polished and used to polish the object to be polished, and a concentrated liquid (stock solution of polishing liquid) that is diluted and used as a polishing liquid.

[0065] <Concentrate> The polishing composition disclosed herein may be in a concentrated form (i.e., in the form of a concentrated polishing liquid) before being supplied to an object to be polished. Such a concentrated polishing composition is advantageous from the viewpoints of convenience and cost reduction during production, distribution, storage, etc. The concentration ratio is not particularly limited, and can be, for example, about 2 to 100 times in volume terms, and is suitably about 5 to 50 times (e.g., about 10 to 40 times). Such a concentrate can be diluted at a desired time to prepare a polishing liquid (working slurry), which can then be supplied to the object to be polished. The dilution can be carried out, for example, by adding water to the concentrate and mixing the mixture.

[0066] The content of abrasive grains in the concentrate can be, for example, 25% by weight or less. From the viewpoints of dispersion stability and filterability of the polishing composition, the content is preferably 20% by weight or less, more preferably 15% by weight or less. In some preferred embodiments, the content of abrasive grains may be 10% by weight or less, or may be 5% by weight or less. Furthermore, from the viewpoints of convenience and cost reduction during production, distribution, storage, etc., the content of abrasive grains in the concentrate can be, for example, 0.1% by weight or more, preferably 0.5% by weight or more, more preferably 0.7% by weight or more, and even more preferably 1% by weight or more.

[0067] <Preparation of Polishing Composition> The polishing composition used in the technology disclosed herein may be a single-component type or a multi-component type such as a two-component type. For example, the polishing composition may be configured so that a polishing liquid is prepared by mixing a part A containing at least abrasive grains among the components of the polishing composition with a part B containing at least a portion of the remaining components, and then mixing and diluting these at an appropriate timing as needed.

[0068] The method for preparing the polishing composition is not particularly limited. For example, the components constituting the polishing composition may be mixed using a well-known mixing device such as a blade mixer, an ultrasonic disperser, or a homomixer. The manner in which these components are mixed is not particularly limited. For example, all the components may be mixed at once, or may be mixed in an appropriately set order.

[0069] <Application> The polishing composition disclosed herein can be used to polish objects of various materials and shapes. Examples of the material of the object to be polished include metals or semimetals, such as silicon, aluminum, nickel, tungsten, copper, tantalum, titanium, and stainless steel, or alloys thereof; glassy materials, such as quartz glass, aluminosilicate glass, and glassy carbon; ceramic materials, such as alumina, silica, sapphire, silicon nitride, tantalum nitride, and titanium carbide; compound semiconductor substrate materials, such as silicon carbide, gallium nitride, and gallium arsenide; and resin materials, such as polyimide resin. The object to be polished may be composed of multiple materials selected from these. The shape of the object to be polished is not particularly limited. The polishing composition disclosed herein can be used to polish objects having flat surfaces, such as plate-like or polyhedral shapes, or to polish the edge of the object to be polished (e.g., wafer edge polishing).

[0070] The polishing composition disclosed herein can be particularly preferably used for polishing a surface made of silicon (typically, polishing a silicon wafer). A typical example of the silicon wafer referred to here is a silicon single crystal wafer, for example, a silicon single crystal wafer obtained by slicing a silicon single crystal ingot.

[0071] The polishing composition disclosed herein can be preferably applied to a polishing step of an object to be polished (e.g., a silicon wafer). Before the polishing step with the polishing composition disclosed herein, the object to be polished may be subjected to a general treatment that can be applied to an object to be polished in a step upstream of the polishing step, such as lapping or etching.

[0072] The polishing composition disclosed herein is effective when used in the finishing step of an object to be polished (e.g., a silicon wafer) or in the polishing step immediately preceding it, and is particularly preferably used in the finishing polishing step. Here, the finishing polishing step refers to the final polishing step in the manufacturing process of the object (i.e., a step in which no further polishing is performed after that step). The polishing composition disclosed herein may also be used in a polishing step upstream of the finishing polishing (a preliminary polishing step between the rough polishing step and the final polishing step, which typically includes at least a primary polishing step and may further include secondary, tertiary, etc. polishing steps), for example, a polishing step performed immediately preceding the finishing polishing.

[0073] The polishing composition disclosed herein is effective, for example, for polishing (typically finish polishing or polishing immediately before finish polishing) silicon wafers that have been prepared to a surface roughness of 0.01 nm to 100 nm in an upstream process. Application to finish polishing is particularly preferred. The surface roughness Ra of the object to be polished can be measured, for example, using a laser scanning surface roughness meter "TMS-3000WRC" manufactured by Schmitt Measurement System Inc.

[0074] <Polishing> The polishing composition disclosed herein can be used for polishing an object to be polished, for example, in an embodiment including the following steps: Hereinafter, a preferred embodiment of a method for polishing a silicon wafer as an object to be polished using the polishing composition disclosed herein will be described. That is, a polishing liquid containing any of the polishing compositions disclosed herein is prepared. The preparation of the polishing liquid may include adjusting the concentration (e.g., diluting) of the polishing composition, adjusting the pH, or the like to prepare the polishing liquid. Alternatively, the polishing composition may be used as is as the polishing liquid.

[0075] Next, the polishing liquid is supplied to the object to be polished, and polishing is carried out by a conventional method. For example, when performing finish polishing of a silicon wafer, typically, a silicon wafer that has undergone a lapping process is set in a general polishing device, and the polishing liquid is supplied to the surface of the silicon wafer to be polished through the polishing pad of the polishing device. Typically, while continuously supplying the polishing liquid, the polishing pad is pressed against the surface of the silicon wafer to be polished, and the two are moved relatively (for example, rotated). Polishing of the object to be polished is completed through this polishing process.

[0076] The polishing pad used in the polishing step is not particularly limited. For example, a polishing pad of a foamed polyurethane type, a nonwoven fabric type, a suede type, or the like can be used. Each polishing pad may contain abrasive grains or may not contain abrasive grains. Usually, a polishing pad that does not contain abrasive grains is preferably used.

[0077] The object to be polished using the polishing composition disclosed herein is typically cleaned. Cleaning can be performed using an appropriate cleaning solution. The cleaning solution used is not particularly limited, and examples include SC-1 cleaning solution (a mixture of ammonium hydroxide (NH4OH), hydrogen peroxide (HO2), and water (HO)) and SC-2 cleaning solution (a mixture of HCl, HO2, and HO), which are commonly used in the semiconductor field. The temperature of the cleaning solution can be, for example, from room temperature (typically about 15°C to 25°C) to about 90°C. From the viewpoint of improving the cleaning effect, a cleaning solution of about 50°C to 85°C can be preferably used.

[0078] As described above, the technology disclosed herein can include a method for manufacturing a polished product (e.g., a method for manufacturing a silicon wafer) that includes a polishing step (preferably finish polishing) by any of the polishing methods described above, and the provision of a polished product (e.g., a silicon wafer) manufactured by the method. [Example]

[0079] Several examples of the present invention will be described below, but it is not intended that the present invention be limited to those shown in these examples. In the following description, "parts" and "%" are by weight unless otherwise specified.

[0080] <Preparation of Polishing Composition> Examples 1 and 2 Abrasive grains, a water-soluble copolymer, a basic compound, and deionized water were mixed to prepare polishing composition concentrates according to the examples. Colloidal silica (average secondary particle diameter: 45 nm) was used as the abrasive grains. The water-soluble copolymer was a block copolymer (PACMO-PVA) composed of N-acryloylmorpholine units (ACMO units) and vinyl alcohol units (VA units), synthesized using the monomer raw materials in the copolymerization ratio (molar ratio) shown in Table 1. Ammonia was used as the basic compound. The weight-average molecular weight (Mw) of the copolymer used in each example is shown in Table 1. The resulting polishing composition concentrate was diluted 20 times by volume with deionized water (DIW) to a concentration of 0.18% abrasive grains, 0.0088% water-soluble copolymer, and 0.005% basic compound.

[0081] (Comparative Example 1) As the water-soluble polymer, polyacryloylmorpholine (PACMO) having the Mw shown in Table 1 was used instead of PACMO-PVA. Otherwise, the polishing composition of this example was prepared in the same manner as in Example 1.

[0082] (Comparative Example 2) As the water-soluble polymer, instead of PACMO-PVA, polyvinyl alcohol (PVA) having the Mw shown in Table 1 was used. Otherwise, in the same manner as in Example 1, a polishing composition according to this example was prepared.

[0083] Examples 3 to 8 Abrasive grains, a water-soluble copolymer, a basic compound, a surfactant, and deionized water were mixed to prepare polishing composition concentrates according to the examples. Colloidal silica (average secondary particle diameter: 45 nm) was used as the abrasive grains. The water-soluble copolymer was a block copolymer (PACMO-PVA) composed of N-acryloylmorpholine units (ACMO units) and vinyl alcohol units (VA units), synthesized using the monomer raw materials in the copolymerization ratio (molar ratio) shown in Table 2. Ammonia was used as the basic compound, and polyoxyethylene decyl ether (CEO5) with 5 moles of ethylene oxide added was used as the surfactant. The weight-average molecular weights (Mw) of the copolymers used in each example are shown in Table 2. The resulting polishing composition concentrate was diluted 20 times by volume with deionized water (DIW) to obtain a polishing composition with an abrasive grain concentration of 0.18%, a water-soluble copolymer concentration of 0.0088%, a basic compound concentration of 0.005%, and a surfactant concentration of 0.0002%.

[0084] (Comparative Example 3) As the water-soluble polymer, instead of PACMO-PVA, polyacryloylmorpholine (PACMO) having the Mw shown in Table 2 was used. Otherwise, the polishing composition of this example was prepared in the same manner as in Example 3.

[0085] Comparative Example 4 As the water-soluble polymer, instead of PACMO-PVA, polyvinyl alcohol (PVA) having the Mw shown in Table 2 was used. Otherwise, the polishing composition of this example was prepared in the same manner as in Example 3.

[0086] <Silicon wafer polishing> The polishing target was a commercially available silicon single crystal wafer with a diameter of 200 mm (conductivity type: P type, crystal orientation: <100> Silicon wafers (COP (Crystal Originated Particle)-free) were prepared by pre-polishing under the following polishing condition 1. Pre-polishing was performed using a polishing solution containing 1.0% abrasive grains (colloidal silica with an average secondary particle diameter of 55 nm) and 0.068% potassium hydroxide in deionized water.

[0087] [Polishing conditions 1] Polishing equipment: Single-wafer polishing equipment model "PNX-322" manufactured by Okamoto Machine Tools Manufacturing Co., Ltd. Polishing load: 15kPa Rotation speed of the surface plate: 30 rpm Head (carrier) rotation speed: 30 rpm Polishing pad: Fujibo Ehime Co., Ltd. Product name "FP55" Pre-polishing liquid supply rate: 550 mL / min Pre-polishing liquid temperature: 20℃ Plate cooling water temperature: 20℃ Polishing time: 3min

[0088] The polishing compositions according to the examples prepared above were used as polishing liquids to polish the silicon wafers that had been pre-polished as described above under the following polishing conditions 2.

[0089] [Polishing conditions 2] Polishing equipment: Single-wafer polishing equipment model "PNX-322" manufactured by Okamoto Machine Tools Manufacturing Co., Ltd. Polishing load: 15kPa Rotation speed of the surface plate: 30 rpm Head (carrier) rotation speed: 30 rpm Polishing pad: Fujibo Ehime Co., Ltd. Product name "POLYPAS27NX" Polishing liquid supply rate: 400 mL / min Polishing solution temperature: 20℃ Plate cooling water temperature: 20℃ Polishing time: 4 min

[0090] The polished silicon wafer was removed from the polishing machine and cleaned using a cleaning solution of NH4OH (29%): HO2 (31%): deionized water = 1:1:12 (volume ratio) (SC-1 cleaning). Specifically, two cleaning tanks, a first and a second, were prepared, each containing the above cleaning solution and maintained at 60°C. The polished silicon wafer was immersed in the first cleaning tank for 5 minutes, then passed through a rinse tank in which it was immersed in ultrapure water and subjected to ultrasonic waves, then immersed in the second cleaning tank for 5 minutes, passed through a rinse tank in which it was immersed in ultrapure water and subjected to ultrasonic waves, and then dried using a spin dryer.

[0091] <Haze measurement> After cleaning, the surface of the silicon wafer was inspected using a wafer inspection device manufactured by KLA Tencor, product name "Surfscan SP2 XP The haze (ppm) was measured in DWO mode using a meter. The results were converted into relative values ​​(haze ratios) with the haze value for Comparative Example 2 set to 100%, and are shown in Tables 1 and 2. If the haze ratio is less than 100%, it can be said that a significant haze improvement effect can be confirmed, and the smaller the haze ratio value, the greater the haze improvement effect.

[0092] [Table 1]

[0093] As shown in Table 1, the polishing compositions of Examples 1 and 2, which used PACMO-PVA as the water-soluble copolymer, had a smaller haze ratio and a greater haze improvement effect than the polishing composition of Comparative Example 2, which used PVA as the water-soluble polymer. The above results show that a polishing composition containing abrasive grains, a water-soluble copolymer, a basic compound, and water, wherein the water-soluble copolymer is a copolymer having N-(meth)acryloylmorpholine units and vinyl alcohol units, can improve the surface quality of the object to be polished after polishing.

[0094] [Table 2]

[0095] As shown in Table 2, the polishing compositions of Examples 3 to 8, which used PACMO-PVA as the water-soluble copolymer, had smaller haze ratios and a greater haze improvement effect than the polishing composition of Comparative Example 4, which used PVA as the water-soluble polymer. In the above examples, the haze ratio decreased as the proportion of ACMO units increased, indicating a tendency for haze improvement, with Example 7 achieving the best results. Furthermore, the haze ratio of Comparative Example 3, which used only PACMO as the water-soluble polymer, was greater than that of Comparative Example 4, which used PVA alone, resulting in a poorer haze improvement effect. The above results show that the surface quality of the object to be polished after polishing can also be improved by using a polishing composition containing abrasive grains, a water-soluble copolymer, a basic compound, a surfactant, and water, wherein the water-soluble copolymer is a copolymer having N-(meth)acryloylmorpholine units and vinyl alcohol units.

[0096] Although specific examples of the present invention have been described above in detail, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and alterations of the specific examples exemplified above.

Claims

1. The abrasive includes silica particles as abrasive grains, a water-soluble copolymer, a basic compound, and water, the silica particles are colloidal silica having an average secondary particle diameter of 15 nm or more and 300 nm or less, the water-soluble copolymer is a copolymer having N-(meth)acryloylmorpholine units and vinyl alcohol units, The water-soluble copolymer has a weight average molecular weight of 2×10 3 or more and 10×10 5 or less, The polishing composition, wherein the basic compound is at least one selected from the group consisting of nitrogen-containing organic basic compounds, nitrogen-containing inorganic basic compounds, phosphorus-containing basic compounds, alkali metal hydroxides, alkaline earth metal hydroxides, ammonium carbonate, potassium carbonate, sodium carbonate, ammonium bicarbonate, potassium bicarbonate, and sodium bicarbonate.

2. The weight average molecular weight of the water-soluble copolymer is 1×10 ４ The polishing composition according to claim 1, wherein the polishing composition has a surface area of ​​10×10 5 or more and 10×10 5 or less.

3. The polishing composition according to claim 1 or 2, further comprising a surfactant or a water-soluble polymer.

4. The polishing composition according to claim 3 , wherein the surfactant or the water-soluble polymer comprises a surfactant or an oxyalkylene polymer containing a polyoxyalkylene structure.

5. The polishing composition according to any one of claims 1 to 4, which is used in a finish polishing step of a silicon wafer.

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