Polishing composition for silicon wafers and its use

Abstract

To provide a novel polishing composition suited to polishing. Provided is polishing composition for silicon wafers. The polishing composition contains a basic compound, a surfactant, and water. The surfactant is an acetylene-glycol-type compound having one acetylene group per molecule and moreover is a compound to which an alkylene oxide has furthermore been added.

Description

[Technical Field]

[0001] The present invention relates to a polishing composition for silicon wafers and a method for polishing silicon wafers using the polishing composition. This application claims priority to Japanese Patent Application No. 2020-198395, filed on 30 November 2020, the entire contents of which are incorporated herein by reference. [Background technology]

[0002] Conventionally, precision polishing has been performed on the surfaces of materials such as metals, metalloids, nonmetals, and their oxides using polishing compositions. For example, the surface of a silicon wafer used as a component of semiconductor products is generally finished to a high-quality mirror surface through a lapping process (rough polishing process) and a polishing process (precision polishing process). The above polishing process typically includes a preliminary polishing process and a finishing polishing process (final polishing process). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2008-147651 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] Polishing compositions are used that possess the ability to efficiently polish the object to be polished. For example, chemical polishing action (alkaline etching) using basic compounds is used to polish semiconductor substrates such as silicon wafers and other substrates. Abrasive grains are used in the above polishing as needed, and in addition to the chemical polishing action, higher processing power can be achieved based on the mechanical polishing action of the abrasive grains. Furthermore, polishing compositions used for polishing the above substrates are required to have the ability to achieve a high-quality surface after polishing. Improvement of the surface quality of the polished surface is achieved by methods such as including additives such as surfactants in the polishing composition and protecting the substrate with the additives. Prior art that has considered the use of additives can be found in, for example, Patent Document 1. However, the use of the above additives may lead to a decrease in processing power, and it is not easy to balance the quality of the polished surface with the polishing rate. In the field of polishing as described above, polishing components are being studied from various perspectives, and for example, compositions that can balance the improvement of the polished surface quality and the polishing rate, which are generally considered to be in a trade-off relationship as described above, are being studied.

[0005] This invention was created against the above background and aims to provide a novel composition suitable for polishing. [Means for solving the problem]

[0006] This specification provides a polishing composition for silicon wafers. This polishing composition comprises a basic compound, a surfactant, and water. The surfactant is an acetylene glycol type compound having one acetylene group in one molecule, further to which an alkylene oxide is added. With such a composition, the action of the surfactant with a specific structure having one acetylene group in one molecule and further an alkylene oxide allows for good chemical polishing action by the basic compound while maintaining or improving the surface quality of the polished surface. In other words, a composition suitable for polishing is provided.

[0007] In some preferred embodiments, using a compound represented by the following formula (1) as a surfactant makes it easier to achieve a good balance between a high-quality polished surface and a high polishing rate.

[0008] [ka] (In formula (1), R 1 ~R 4 Each is independently a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, and R 5 , R 6 Each of these is an independent substituted or unsubstituted alkylene group with 1 to 5 carbon atoms, where m is an integer greater than or equal to 1, n is an integer greater than or equal to 0, and m + n ≤ 50.

[0009] In some preferred embodiments, the polishing composition further includes abrasive particles. By including abrasive particles in the polishing composition, the polishing rate can be improved based on the mechanical polishing action provided by the abrasive particles. By including a surfactant of the above-mentioned specific structure in a composition containing abrasive particles and a basic compound, the polishing rate can be improved while maintaining or improving the surface quality after polishing. Silica particles are preferably used as the abrasive particles. By using silica particles as abrasive particles, it is easier to achieve a good balance between a high-quality polished surface and a high polishing rate. The effect of including a surfactant of the above-mentioned specific structure is suitably realized in a polishing composition containing silica particles as abrasive particles.

[0010] In some preferred embodiments, the polishing composition further comprises a water-soluble polymer. A high-quality polished surface is preferably achieved with a composition comprising the surfactant of the specific structure described above and a water-soluble polymer.

[0011] In some preferred embodiments, the pH of the polishing composition is 8.0 to 12.0. The effects of the techniques disclosed herein can be preferably exhibited in compositions having a pH within this range.

[0012] Furthermore, this specification provides a method for polishing a silicon wafer using any of the polishing compositions disclosed herein. The polishing method includes a polishing step. In the polishing step, the silicon wafer is polished using a silicon wafer polishing composition comprising a surfactant of the specific structure, a basic compound, and water. In some preferred embodiments, the polishing method includes a preliminary polishing step and a final polishing step, wherein polishing is performed using the polishing composition disclosed herein in the final polishing step. According to this polishing method, a higher quality silicon wafer surface can be efficiently obtained in the final polishing step. [Modes for carrying out the invention]

[0013] Preferred embodiments of the present invention will be described below. Matters other than those specifically mentioned herein that are necessary for carrying out the present invention can be understood as design matters for those skilled in the art based on the prior art. The present invention can be carried out based on the contents disclosed herein and common technical knowledge in the art.

[0014] <Surfactant A> The polishing composition disclosed herein is characterized by containing a surfactant (hereinafter also referred to as "surfactant A" for convenience) which is an acetylene glycol type compound having one acetylene group in one molecule and further having an alkylene oxide added to it. Polishing using the polishing composition containing surfactant A of the above specific structure allows for good chemical polishing action by the basic compound described later, and maintains or improves the surface quality of the polished surface. This is because surfactant A of the above specific structure, by simultaneously having an acetylene structure and an alkylene oxide structure, protects the substrate surface appropriately without excessively suppressing alkaline etching by the basic compound. The action of surfactant A is not limited to the above action. From the viewpoint of improving surface quality, a nonionic surfactant A is more preferred as surfactant A. Surfactant A can be used alone or in combination of two or more types.

[0015] A preferred example of surfactant A is a compound represented by the following general formula (1).

[0016] [ka]

[0017] In the above equation (1), R 1 ~R 4 Each of these is independently a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms. 1 ~R 4The number of carbon atoms of the alkyl group may be 1 or more, 2 or more, 3 or more, 20 or less, 18 or less, 16 or less, 12 or less, 10 or less, 8 or less, or 5 or less. Specific examples of the alkyl group include methyl group, ethyl group, propyl group, iso-propyl group, butyl group, iso-butyl group, sec-butyl group, tert-butyl group, pentyl group, iso-pentyl group, neo-pentyl group, tert-pentyl group, hexyl group, octyl group, nonyl group, decyl group, lauryl group, myristyl group, palmityl group, stearyl group, etc. R 1 ~R 4 may be the same or different.

[0018] In the above formula (1), R 5 and R 6 are each independently a substituted or unsubstituted alkylene group having 1 to 5 carbon atoms. The number of carbon atoms of the alkylene group for R 5 and R 6 may be 1 or more, 2 or more, 3 or more, or 4 or less, 3 or less. Specific examples of the alkylene group include ethylene group, propylene group, butylene group, pentylene group, etc. R 5 and R 6 may be the same or different.

[0019] In the above formula (1), m is an integer of 1 or more, n is an integer of 0 or more, and m + n ≤ 50 is satisfied. m + n may be 1 or more, 3 or more, 5 or more, 10 or more, 15 or more, 20 or more, or 50 or less, 30 or less, 22 or less, 16 or less, 12 or less, 8 or less, 4 or less (for example, 3 or less). m and n may be the same or different.

[0020] Furthermore, since it is difficult to completely control m and n in formula (1) above, surfactant A can be used in a manner that includes multiple compounds with different m+n values. Also, surfactant A can be used in a manner that further includes compounds having a structure where m=n=0. In these cases, the average value of m+n (hereinafter also referred to as the "average number of added moles") may be 1 or more, 3 or more, 5 or more, 10 or more, 15 or more, 20 or more, 50 or less, 30 or less, 22 or less, 16 or less, 12 or less, 8 or less, or 4 or less (for example, 3 or less).

[0021] As surfactant A, one having an appropriate molecular weight that exerts its effect in the abrasive composition is used, and is not limited to a specific molecular weight. Typically, the molecular weight of surfactant A is 250 or more, for example 300 or more, preferably 400 or more, more preferably 500 or more, and may also be 700 or more, 1200 or more, or 1500 or more. The upper limit of the above molecular weight is, for example, 3000 or less, 2000 or less is appropriate, and may also be 1400 or less, 1000 or less, or 600 or less. The molecular weight of surfactant A is determined from the molecular weight calculated from the chemical formula.

[0022] The amount of surfactant A in the abrasive composition should be, for example, 1.0 × 10⁻⁶, from the viewpoint of exhibiting the effect of surfactant A. -6 It can be % by weight or more, and from the viewpoint of surface quality after polishing, it is preferably 5.0 × 10 -6 Weight % or more, comfortably 1.0 × 10 -5 % by weight or more, more preferably 5.0 × 10 -5 % by weight or more, particularly preferably 1.0 × 10 -4The content is 0% by weight or more. Furthermore, the content of surfactant A in the polishing composition is preferably less than 0.2% by weight from the viewpoint of cleaning performance, and may be less than 0.1% by weight, preferably 0.05% by weight or less, more preferably 0.01% by weight or less, may be 0.005% by weight or less, and may be 0.003% by weight or less. These content levels can preferably be applied, for example, to the content in the polishing liquid (working slurry) supplied to the substrate.

[0023] Furthermore, when the polishing composition disclosed herein contains a water-soluble polymer, the content of surfactant A (or the total amount thereof if it contains two or more surfactants) can also be determined by its relative relationship to the water-soluble polymer. Although not particularly limited, in some embodiments, the content of the water-soluble polymer per 100 parts by weight of the water-soluble polymer can be, for example, 0.01 parts by weight or more, and from the viewpoint of haze reduction, etc., it is appropriate to be 0.1 parts by weight or more, preferably 0.5 parts by weight or more, more preferably 1 part by weight or more. Also, the content of surfactant A per 100 parts by weight of the water-soluble polymer may be, for example, 50 parts by weight or less, or 30 parts by weight or less. From the viewpoint of dispersion stability of the polishing composition, etc., in some embodiments, the content of surfactant A per 100 parts by weight of the water-soluble polymer is appropriate to be 15 parts by weight or less, preferably 10 parts by weight or less, and may also be 8 parts by weight or less, or 7 parts by weight or less.

[0024] <Basic compounds> The polishing compositions disclosed herein contain basic compounds. In this specification, a basic compound refers to a compound that dissolves in water and increases the pH of the aqueous solution. By including a basic compound in the polishing composition, the object to be polished can be efficiently polished by its chemical polishing action (alkaline etching). Examples of basic compounds include organic or inorganic basic compounds containing nitrogen, basic compounds containing phosphorus, alkali metal hydroxides, alkaline earth metal hydroxides, various carbonates and bicarbonates, etc. 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. Such basic compounds can be used individually or in combination of two or more.

[0025] 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.

[0026] As quaternary ammonium compounds, quaternary ammonium salts (typically strong bases) such as tetraalkylammonium salts and hydroxyalkyltrialkylammonium salts can be used. The anionic component in such quaternary ammonium salts is, for example, OH - F- Cl - , Br - , I - ClO4 - BH4 - These may include the above. An example of the above quaternary ammonium compound is an anion OH - Examples include quaternary ammonium salts, i.e., quaternary ammonium hydroxides. Specific examples of quaternary ammonium hydroxides include tetraalkylammonium hydroxides such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetrapentylammonium hydroxide, and tetrahexylammonium hydroxide; and hydroxyalkyltrialkylammonium hydroxides such as 2-hydroxyethyltrimethylammonium hydroxide (also known as choline); and so on.

[0027] Of these basic compounds, at least one basic compound selected from alkali metal hydroxides, quaternary ammonium hydroxides, and ammonia can be preferably used. Among these, tetraalkylammonium hydroxide (e.g., tetramethylammonium hydroxide) and ammonia are more preferred, and ammonia is particularly preferred.

[0028] The content of basic compounds in the polishing composition is not particularly limited. From the viewpoint of improving the polishing rate, etc., it is usually appropriate to have a content of 0.0005% by weight or more, preferably 0.001% by weight or more, and more preferably 0.003% by weight or more. Furthermore, from the viewpoint of improving surface quality (e.g., reducing haze), etc., it is appropriate to have a content of less than 0.1% by weight, preferably less than 0.05% by weight, and more preferably less than 0.03% by weight (e.g., less than 0.025% by weight, and even more preferably less than 0.01% by weight). When two or more types are used in combination, the above content refers to the total content of the two or more basic compounds. These content levels can preferably be applied, for example, to the content in the polishing liquid (working slurry) supplied to the substrate.

[0029] While not particularly limited, the polishing compositions disclosed herein preferably contain surfactant A and a basic compound in appropriate ratios. This allows for good chemical polishing action by the basic compound while preferably maintaining or improving the surface quality of the polished surface. Content of surfactant A C A Content of basic compounds relative to C B The ratio (C B / C A ) is, for example, 0.01 or more, and from the viewpoint of exhibiting the effect of adding basic compounds, it is preferably 0.1 or more, more preferably 0.3 or more, even more preferably 0.8 or more, and may be 1 or more, or 3 or more. Also, the above ratio (C B / C A ) can be 100 or less, and from the viewpoint of better exhibiting the added effect of surfactant A, it is preferably 70 or less, more preferably 60 or less, and may be, for example, 50 or less, or 40 or less.

[0030] <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 avoid as much as possible the inhibition of the function of other components contained in the polishing composition, the water used should preferably have a total content of transition metal ions of 100 ppb or less. For example, the purity of the water can be increased by operations such as removal of impurity ions with an ion exchange resin, removal of foreign matter with a filter, or distillation. The polishing composition disclosed herein may further contain an organic solvent (lower alcohol, lower ketone, etc.) that can be uniformly mixed with water, if necessary. It is preferable that 90% or more by volume of the solvent contained in the polishing composition is water, and it is more preferable that 95% or more by volume (for example, 99-100% by volume) is water.

[0031] <Abrasive grains> The polishing compositions disclosed herein may or may not contain abrasive grains. In some preferred embodiments, the polishing compositions contain abrasive grains. The abrasive grains function to mechanically polish the surface of the substrate. By including abrasive grains in the polishing composition, the polishing rate can be improved based on the mechanical polishing action caused by the inclusion of abrasive grains. The material and properties of the abrasive grains are not particularly limited and can be appropriately selected according to the purpose 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 (where (meth)acrylic acid comprehensively refers to acrylic acid and methacrylic acid), and polyacrylonitrile particles. Such abrasive particles may be used individually or in combination of two or more types.

[0032] As the abrasive grains, inorganic particles are preferred, and among these, particles made of metal or metalloid oxides are preferred, with silica particles being particularly preferred. In polishing compositions that can be used for polishing substrates having a silicon surface, such as silicon wafers described later (e.g., finish polishing), the use of silica particles as abrasive grains is particularly significant. The technology disclosed herein can preferably be carried out, for example, in a manner in which the abrasive grains consist substantially 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.

[0033] Specific examples of silica particles include colloidal silica, fumed silica, and precipitated silica. Silica particles can be used individually or in combination of two or more types. Colloidal silica is particularly preferred because it easily yields a polished surface with excellent surface quality after polishing. As colloidal silica, for example, colloidal silica produced from water glass (sodium silicate) by ion exchange or colloidal silica produced by alkoxide method (colloidal silica produced by hydrolysis condensation reaction of alkoxysilane) can be preferably used. Colloidal silica can be used individually or in combination of two or more types.

[0034] The true specific gravity of the abrasive grain constituent material (e.g., silica constituting silica particles) is preferably 1.5 or higher, more preferably 1.6 or higher, and even more preferably 1.7 or higher. While there is no particular upper limit to the true specific gravity of silica, it is typically 2.3 or lower, preferably 2.2 or lower, more preferably 2.0 or lower, and for example, 1.9 or lower. The true specific gravity of the abrasive grain (e.g., silica particles) can be measured using a liquid displacement method with ethanol as the displacement solution.

[0035] The average primary particle diameter of the abrasive grains (typically silica particles) is not particularly limited, but from the viewpoint of polishing rate, 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 above average primary particle diameter is preferably 15 nm or more, and more preferably 20 nm or more (e.g., greater than 20 nm). Also, from the viewpoint of preventing scratches, 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 45 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 43 nm or less, less than 40 nm, less than 38 nm, less than 35 nm, less than 32 nm, or less than 30 nm.

[0036] In this specification, the average primary particle diameter is calculated from the specific surface area (BET value) measured by the BET method as follows: Average primary particle diameter (nm) = 6000 / (True density (g / cm³) 3 ) × BET value (m 2 This refers to the particle size (BET particle size) calculated by the formula ( / g). The specific surface area can be measured, for example, using a surface area measuring device manufactured by Micromeritex, product name "Flow Sorb II 2300".

[0037] The average secondary particle diameter of the abrasive grains (e.g., silica particles) is not particularly limited and can be appropriately selected from a range of approximately 15 nm to 300 nm. From the viewpoint of improving the polishing rate, the average secondary particle diameter is preferably 30 nm or more, and 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, and preferably 44 nm or more. Also, the average secondary particle diameter is usually advantageous to be 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 50 nm or less.

[0038] In this specification, the average secondary particle diameter refers to the particle diameter (volume-average particle diameter) measured by dynamic light scattering. The average secondary particle diameter of abrasive grains can be measured, for example, by dynamic light scattering using "NanoTrack® UPA-UT151" manufactured by Nikkiso Co., Ltd.

[0039] The shape (outer form) of the abrasive grains may be spherical or non-spherical. Specific examples of non-spherical particles include peanut-shaped (i.e., the shape of a peanut shell), cocoon-shaped, konpeito-shaped, and rugby ball-shaped particles. For example, abrasive grains in which most of the particles are peanut-shaped or cocoon-shaped may be preferably used.

[0040] While not particularly limited, the average aspect ratio of the major axis to minor axis of the abrasive grains (average aspect ratio) is, in principle, 1.0 or higher, preferably 1.05 or higher, and more preferably 1.1 or higher. A higher polishing rate can be achieved by increasing the average aspect ratio. Furthermore, from the viewpoint of reducing scratches, the average aspect ratio of the abrasive grains is preferably 3.0 or lower, more preferably 2.0 or lower, and even more preferably 1.5 or lower.

[0041] The shape (outer shape) and average aspect ratio of abrasive grains can be determined, for example, by electron microscopy observation. A specific procedure for determining the average aspect ratio is to use a scanning electron microscope (SEM) to draw the smallest rectangle circumscribing each grain image for a predetermined number of abrasive grains (e.g., 200 grains) whose individual grain shapes can be recognized. Then, for each rectangle drawn for each grain image, the ratio of the major axis to the minor axis is calculated by dividing the length of the major side (major axis value) by the length of the minor side (minor axis value). The average aspect ratio can be obtained by taking the arithmetic mean of the aspect ratios of the predetermined number of grains.

[0042] When the polishing composition contains abrasive grains, the abrasive grain content in the polishing composition is not particularly limited, but is preferably 0.01% by weight or more, 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. A higher polishing rate can be achieved by increasing the abrasive grain content. The above content is suitable to be 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, 0.5% by weight or less, or 0.4% by weight or less. This makes it possible to achieve a higher quality surface. The above abrasive grain content can preferably be adopted in embodiments in which the polishing composition is used in the form of a polishing liquid (working slurry).

[0043] <Water-soluble polymer> The polishing compositions disclosed herein may contain water-soluble polymers. Water-soluble polymers can be useful for protecting the substrate surface and improving the wettability of the substrate surface after polishing. For example, by selecting and using a suitable water-soluble polymer in addition to surfactant A, it is possible to better balance the surface quality after polishing and the polishing rate. In some embodiments, water-soluble polymers include compounds containing hydroxyl groups, carboxyl groups, acyloxy groups, sulfo groups, amide structures, imide structures, quaternary ammonium structures, heterocyclic structures, vinyl structures, etc., in the molecule. Examples of water-soluble polymers include cellulose derivatives, starch derivatives, polymers containing oxyalkylene units, polyvinyl alcohol-based polymers, and polymers containing nitrogen atoms. As one embodiment of polymers containing nitrogen atoms, N-vinyl type polymers and N-(meth)acryloyl type polymers may be used. Water-soluble polymers may be polymers derived from natural products or synthetic polymers. Water-soluble polymers may be used individually or in combination of two or more types.

[0044] In some embodiments, polymers derived from natural products are used as water-soluble polymers. Examples of polymers derived from natural products include cellulose derivatives and starch derivatives. The polymers derived from natural products may be used individually or in combination of two or more.

[0045] In some embodiments, cellulose derivatives are used as water-soluble polymers. Here, the cellulose derivative is a polymer containing β-glucose units as its main repeating units. Specific examples of cellulose derivatives include hydroxyethylcellulose (HEC), hydroxypropylcellulose, hydroxyethylmethylcellulose, hydroxypropylmethylcellulose, methylcellulose, ethylcellulose, ethylhydroxyethylcellulose, and carboxymethylcellulose. Among these, HEC is preferred. Cellulose derivatives may be used individually or in combination of two or more.

[0046] In some other embodiments, starch derivatives are used as water-soluble polymers. Starch derivatives are polymers containing α-glucose units as the main repeating units, and examples include pregelatinized starch, pullulan, carboxymethyl starch, and cyclodextrin. Starch derivatives may be used individually or in combination of two or more.

[0047] In some other embodiments, synthetic polymers are used as the water-soluble polymers. The effects of the techniques disclosed herein are preferably exhibited in embodiments in which synthetic polymers are used as the water-soluble polymers. The synthetic polymers may be used individually or in combination of two or more types.

[0048] In some embodiments, polymers containing oxyalkylene units are used as water-soluble polymers. Examples of polymers containing oxyalkylene units include polyethylene oxide (PEO), block copolymers of ethylene oxide (EO) and propylene oxide (PO) or butylene oxide (BO), and random copolymers of EO and PO or BO. Among these, block copolymers of EO and PO or random copolymers of EO and PO are preferred. Block copolymers of EO and PO may be diblock copolymers or triblock copolymers containing PEO blocks and polypropylene oxide (PPO) blocks. Examples of the above triblock copolymers include PEO-PPO-PEO type triblock copolymers and PPO-PEO-PPO type triblock copolymers. Generally, PEO-PPO-PEO type triblock copolymers are more preferred.

[0049] In this specification, unless otherwise specified, the term "polymer" comprehensively refers to various types of copolymers, including random copolymers, alternating copolymers, block copolymers, and graft copolymers.

[0050] In block copolymers or random copolymers of EO and PO, the molar ratio (EO / PO) of EO and PO constituting the copolymer is preferably greater than 1, more preferably 2 or more, and even more preferably 3 or more (for example, 5 or more) from the viewpoint of solubility in water and washability.

[0051] In some preferred embodiments, a polyvinyl alcohol-based polymer is used as the water-soluble polymer. Compositions containing a polyvinyl alcohol-based polymer make it easier to improve the polishing rate while maintaining the surface quality after polishing. A polyvinyl alcohol-based polymer refers to a polymer that contains vinyl alcohol units (hereinafter also referred to as "VA units") as its repeating units. A polyvinyl alcohol-based polymer may contain only VA units as its repeating units, or it may contain repeating units other than VA units (hereinafter also referred to as "non-VA units") in addition to VA units. A polyvinyl alcohol-based polymer may be a random copolymer containing VA units and non-VA units, a block copolymer, an alternating copolymer, or a graft copolymer. A polyvinyl alcohol-based polymer may contain only one type of non-VA unit, or it may contain two or more types of non-VA units.

[0052] The above polyvinyl alcohol polymer may be unmodified polyvinyl alcohol (non-modified PVA) or modified polyvinyl alcohol (modified PVA). Here, non-modified PVA refers to a polyvinyl alcohol polymer produced by hydrolysis (saponification) of polyvinyl acetate, which substantially does not contain repeating units other than the vinyl polymerized vinyl acetate structure (-CH2-CH(OCOCH3)-) and VA units. The degree of saponification of the above non-modified PVA may be, for example, 60% or more, and may be 70% or more, 80% or more, or 90% or more from the viewpoint of water solubility.

[0053] The polyvinyl alcohol-based polymer may be a modified PVA comprising VA units and non-VA units having at least one structure selected from oxyalkylene groups, carboxyl groups, (di)carboxylic acid groups, (di)carboxylic acid esters, phenyl groups, naphthyl groups, sulfo groups, amino groups, hydroxyl groups, amide groups, imide groups, nitrile groups, ether groups, ester groups, and salts thereof.

[0054] Furthermore, non-VA units that may be included in modified PVA may include, but are not limited to, repeating units derived from N-vinyl type monomers or N-(meth)acryloyl type monomers, repeating units derived from ethylene, repeating units derived from alkyl vinyl ethers, repeating units derived from vinyl esters of monocarboxylic acids having 3 or more carbon atoms, etc. A preferred example of the above N-vinyl type monomer is N-vinylpyrrolidone. A preferred example of the above N-(meth)acryloyl type monomer is N-(meth)acryloylmorpholine. The above alkyl vinyl ether may be, for example, propyl vinyl ether, butyl vinyl ether, 2-ethylhexyl vinyl ether, etc., which are vinyl ethers having an alkyl group with 1 to 10 carbon atoms. The above vinyl ester of monocarboxylic acid having 3 or more carbon atoms may be, for example, vinyl propanoate, vinyl butanoate, vinyl pentanoate, vinyl hexanoate, etc., which are vinyl esters of monocarboxylic acids having 3 to 7 carbon atoms.

[0055] Furthermore, the polyvinyl alcohol polymer may be an acetalized polyvinyl alcohol polymer. Examples of acetalized polyvinyl alcohol polymers include modified PVA in which some of the VA units contained in the polyvinyl alcohol polymer are acetalized with an aldehyde. As the aldehyde, for example, alkyl aldehydes can be preferably used, and alkyl aldehydes having an alkyl group with 1 to 7 carbon atoms are preferred, with acetaldehyde, n-propyl aldehyde, n-butyraldehyde, and n-pentyl aldehyde being particularly preferred.

[0056] As the polyvinyl alcohol-based polymer, a cation-modified polyvinyl alcohol into which a cationic group such as a quaternary ammonium structure has been introduced may be used. Examples of the above-mentioned cation-modified polyvinyl alcohol include those into which a cationic group derived from a monomer having a cationic group, such as diallyldialkylammonium salt or N-(meth)acryloylaminoalkyl-N,N,N-trialkylammonium salt has been introduced.

[0057] As a polyvinyl alcohol-based polymer, the non-VA unit has the chemical formula: -CH2-CH(CR (1) (OR (4) )-CR (2) (OR (5) )-R (3) It may have a structural part represented by )-. Here R (1) ~R (3) Each of these independently represents a hydrogen atom or an organic group, and R (4) and R (5) Each is independently a hydrogen atom or R (6) -CO-(wherein, R (6) ) indicates an alkyl group. ) Examples of such modified PVA include modified PVA having a 1,2-diol structure in its side chain.

[0058] The ratio of moles of VA units to the total number of moles of repeating units constituting the polyvinyl alcohol-based polymer may be, for example, 5% or more, 10% or more, 20% or more, or 30% or more. While not particularly limited, in some embodiments, the ratio of moles of VA units may be 50% or more, 65% or more, 75% or more, 80% or more, or 90% or more (e.g., 95% or more, or 98% or more). It is also possible that substantially 100% of the repeating units constituting the polyvinyl alcohol-based polymer are VA units. Here, "substantially 100%" means that the polyvinyl alcohol-based polymer does not contain non-VA units, at least intentionally, and typically includes cases where the ratio of moles of non-VA units to the total number of moles of repeating units is less than 2% (e.g., less than 1%), and 0%. In some other embodiments, the ratio of moles of VA units to the total number of moles of repeating units constituting the polyvinyl alcohol-based polymer may be, for example, 95% or less, 90% or less, 80% or less, or 70% or less.

[0059] The content of VA units (by weight) in the polyvinyl alcohol polymer may be, for example, 5% by weight or more, 10% by weight or more, 20% by weight or more, or 30% by weight or more. Although not particularly limited, in some embodiments, the content of VA units may be 50% by weight or more (e.g., more than 50% by weight), 70% by weight or more, or 80% by weight or more (e.g., 90% by weight or more, or 95% by weight or more, or 98% by weight or more). Substantially 100% by weight of the repeating units constituting the polyvinyl alcohol polymer may be VA units. Here, "substantially 100% by weight" means that, at least intentionally, no non-VA units are included as repeating units constituting the polyvinyl alcohol polymer, and typically means that the content of non-VA units in the polyvinyl alcohol polymer is less than 2% by weight (e.g., less than 1% by weight). In some other embodiments, the VA unit content in the polyvinyl alcohol-based polymer may be, for example, 95% by weight or less, 90% by weight or less, 80% by weight or less, or 70% by weight or less.

[0060] A polyvinyl alcohol-based polymer may contain multiple polymer chains with different VA unit content within the same molecule. Here, a polymer chain refers to a part (segment) that constitutes a portion of a polymer molecule. For example, a polyvinyl alcohol-based polymer may contain polymer chain A, which has a VA unit content higher than 50% by weight, and polymer chain B, which has a VA unit content lower than 50% by weight (i.e., a non-VA unit content higher than 50% by weight), within the same molecule.

[0061] Polymer chain A may contain only VA units as repeating units, or it may contain non-VA units in addition to VA units. The VA unit content in polymer chain A may be 60% by weight or more, 70% by weight or more, 80% by weight or more, or 90% by weight or more. In some embodiments, the VA unit content in polymer chain A may be 95% by weight or more, or 98% by weight or more. Substantially 100% by weight of the repeating units constituting polymer chain A may be VA units.

[0062] Polymer chain B may contain only non-VA units as repeating units, or it may contain VA units in addition to non-VA units. The content of non-VA units in polymer chain B may be 60% by weight or more, 70% by weight or more, 80% by weight or more, or 90% by weight or more. In some embodiments, the content of non-VA units in polymer chain B may be 95% by weight or more, or 98% by weight or more. Substantially 100% by weight of the repeating units constituting polymer chain B may be non-VA units.

[0063] Examples of polyvinyl alcohol-based polymers containing polymer chain A and polymer chain B in the same molecule include block copolymers and graft copolymers containing these polymer chains. The above graft copolymer may be a graft copolymer in which polymer chain B (side chain) is grafted onto polymer chain A (main chain), or a graft copolymer in which polymer chain A (side chain) is grafted onto polymer chain B (main chain). In one embodiment, a polyvinyl alcohol-based polymer in which polymer chain B is grafted onto polymer chain A can be used.

[0064] Examples of polymer chain B include polymer chains whose main repeating units are derived from N-vinyl monomers, polymer chains whose main repeating units are derived from N-(meth)acryloyl monomers, polymer chains whose main repeating units are derived from vinyl dicarboxylates such as fumaric acid, maleic acid, and maleic anhydride, polymer chains whose main repeating units are derived from aromatic vinyl monomers such as styrene and naphthalene vinyl, and polymer chains whose main repeating units are oxyalkylene units. In this specification, unless otherwise specified, the main repeating unit refers to a repeating unit that is present in an amount exceeding 50% by weight.

[0065] A preferred example of polymer chain B is a polymer chain whose main repeating unit is an N-vinyl type monomer, i.e., an N-vinyl polymer chain. The content of repeating units derived from N-vinyl type monomers in the N-vinyl polymer chain is typically more than 50% by weight, may be 70% or more by weight, 85% or more by weight, or 95% or more by weight. Substantially all of polymer chain B may consist of repeating units derived from N-vinyl type monomers.

[0066] In this specification, examples of N-vinyl type monomers include monomers having a nitrogen-containing heterocyclic ring (e.g., a lactam ring) and N-vinyl chain amides. Specific examples of N-vinyl lactam type monomers include N-vinylpyrrolidone, N-vinylpiperidone, N-vinylmorpholinone, N-vinylcaprolactam, N-vinyl-1,3-oxazin-2-one, and N-vinyl-3,5-morpholindione. Specific examples of N-vinyl chain amides include N-vinylacetamide, N-vinylpropionic acid amide, and N-vinylbutyric acid amide. Polymer chain B may be, for example, an N-vinyl polymer chain in which more than 50% by weight (e.g., 70% or more by weight, or 85% or more by weight, or 95% or more by weight) of its repeating units are N-vinylpyrrolidone units. Substantially all of the repeating units constituting polymer chain B may be N-vinylpyrrolidone units.

[0067] Another example of polymer chain B is a polymer chain whose main repeating unit is an N-(meth)acryloyl type monomer, i.e., an N-(meth)acryloyl polymer chain. The content of repeating units derived from N-(meth)acryloyl type monomers in an N-(meth)acryloyl polymer chain is typically more than 50% by weight, may be 70% or more by weight, 85% or more by weight, or 95% or more by weight. It is also possible that substantially all of polymer chain B consists of repeating units derived from N-(meth)acryloyl type monomers.

[0068] In this specification, examples of N-(meth)acryloyl type monomers include chain amides having an N-(meth)acryloyl group and cyclic amides having an N-(meth)acryloyl group. Examples of chain amides having an N-(meth)acryloyl group include (meth)acrylamides; N-alkyl(meth)acrylamides such as N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N-propyl(meth)acrylamide, N-isopropyl(meth)acrylamide, and Nn-butyl(meth)acrylamide; and N,N-dialkyl(meth)acrylamides such as N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dipropyl(meth)acrylamide, N,N-diisopropyl(meth)acrylamide, and N,N-di(n-butyl)(meth)acrylamide. Examples of cyclic amides having an N-(meth)acryloyl group include N-(meth)acryloylmorpholine and N-(meth)acryloylpyrrolidine.

[0069] Another example of polymer chain B is a polymer chain containing oxyalkylene units as the main repeating units, i.e., an oxyalkylene polymer chain. The oxyalkylene unit content in the oxyalkylene polymer chain is typically more than 50% by weight, may be 70% or more by weight, 85% or more by weight, or 95% or more by weight. Substantially all of the repeating units in polymer chain B may be oxyalkylene units.

[0070] Examples of oxyalkylene units include oxyethylene units, oxypropylene units, and oxybutylene units. Each of these oxyalkylene units may be repeating units derived from the corresponding alkylene oxide. The oxyalkylene polymer chain may contain one type of oxyalkylene unit or two or more types. For example, it may be an oxyalkylene polymer chain containing a combination of oxyethylene units and oxypropylene units. In an oxyalkylene polymer chain containing two or more types of oxyalkylene units, these oxyalkylene units may be random copolymers of the corresponding alkylene oxides, block copolymers, alternating copolymers, or graft copolymers.

[0071] Further examples of polymer chain B include polymer chains containing repeating units derived from alkyl vinyl ethers (e.g., vinyl ethers having alkyl groups with 1 to 10 carbon atoms), polymer chains containing repeating units derived from monocarboxylate vinyl esters (e.g., vinyl esters of monocarboxylic acids with 3 or more carbon atoms), and polymer chains into which cationic groups (e.g., cationic groups having a quaternary ammonium structure) are introduced.

[0072] In the technologies disclosed herein, the polyvinyl alcohol-based polymer used as the water-soluble polymer is preferably a modified polyvinyl alcohol copolymer containing VA units and non-VA units. The degree of saponification of the polyvinyl alcohol-based polymer used as the water-soluble polymer is usually 50 mol% or more, preferably 65 mol% or more, more preferably 70 mol% or more, for example, 75 mol% or more. In principle, the degree of saponification of the polyvinyl alcohol-based polymer is 100 mol% or less.

[0073] In some other embodiments, N-vinyl polymers may be used as water-soluble polymers. Examples of N-vinyl polymers include polymers containing repeating units derived from monomers having nitrogen-containing heterocyclic rings (e.g., lactam rings). Examples of such polymers include homopolymers and copolymers of N-vinyl lactam monomers (e.g., copolymers in which the copolymerization ratio of N-vinyl lactam monomers exceeds 50% by weight), and homopolymers and copolymers of N-vinyl chain amides (e.g., copolymers in which the copolymerization ratio of N-vinyl chain amides exceeds 50% by weight).

[0074] Specific examples of N-vinyllactam monomers (i.e., compounds having a lactam structure and an N-vinyl group within a single molecule) include N-vinylpyrrolidone (VP), N-vinylpiperidone, N-vinylmorpholinone, N-vinylcaprolactam (VC), N-vinyl-1,3-oxazin-2-one, and N-vinyl-3,5-morpholindione. Specific examples of polymers containing N-vinyllactam monomer units include polyvinylpyrrolidone, polyvinylcaprolactam, random copolymers of VP and VC, random copolymers of one or both of VP and VC with other vinyl monomers (e.g., acrylic monomers, vinyl ester monomers, etc.), block copolymers containing polymer chains containing one or both of VP and VC, alternating copolymers, and graft copolymers. Specific examples of N-vinyl chain amides include N-vinylacetamide, N-vinylpropionic acid amide, and N-vinylbutyric acid amide.

[0075] In some other embodiments, N-(meth)acryloyl polymers may be preferably used as water-soluble polymers. The effects of the techniques disclosed herein can be more preferably realized in compositions containing N-(meth)acryloyl polymers. Examples of N-(meth)acryloyl polymers include homopolymers and copolymers of N-(meth)acryloyl monomers (typically copolymers in which the copolymerization ratio of N-(meth)acryloyl monomers exceeds 50% by weight). Examples of N-(meth)acryloyl monomers include chain amides having N-(meth)acryloyl groups and cyclic amides having N-(meth)acryloyl groups.

[0076] Examples of chain-like amides having an N-(meth)acryloyl group include (meth)acrylamide; N-alkyl(meth)acrylamides such as N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N-propyl(meth)acrylamide, N-isopropyl(meth)acrylamide, and Nn-butyl(meth)acrylamide; and N,N-dialkyl(meth)acrylamides such as N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dipropyl(meth)acrylamide, N,N-diisopropyl(meth)acrylamide, and N,N-di(n-butyl)(meth)acrylamide. Examples of polymers containing chain-like amides having an N-(meth)acryloyl group as monomer units include homopolymers of N-isopropylacrylamide and copolymers of N-isopropylacrylamide (for example, copolymers in which the copolymerization ratio of N-isopropylacrylamide exceeds 50% by weight).

[0077] Examples of cyclic amides having an N-(meth)acryloyl group include N-acryloylmorpholine, N-acryloylthiomorpholine, N-acryloylpiperidine, N-acryloylpyrrolidine, N-methacryloylmorpholine, N-methacryloylpiperidine, and N-methacryloylpyrrolidine. An example of a polymer containing a cyclic amide having an N-(meth)acryloyl group as a monomer unit is acryloylmorpholine polymer (PACMO). Typical examples of acryloylmorpholine polymers include homopolymers of N-acryloylmorpholine (ACMO) and copolymers of ACMO (for example, copolymers in which the copolymerization ratio of ACMO exceeds 50% by weight). In acryloylmorpholine polymers, the ratio of the number of moles of ACMO units to the number of moles of total repeating units is usually 50% or more, and is appropriately 80% or more (for example, 90% or more, typically 95% or more). The entire repeating unit of the water-soluble polymer may be substantially composed of ACMO units.

[0078] While not particularly limited, the techniques disclosed herein are preferably implemented in combination of one or more nitrogen-containing polymers (typically N-(meth)acryloyl type polymers) and one or more water-soluble polymers different from the nitrogen-containing polymers (typically N-(meth)acryloyl type polymers) (non-nitrogen-containing polymers, typically non-N-(meth)acryloyl type polymers). By using the above two or more water-soluble polymers in combination, a higher level of both surface quality and polishing rate can be achieved. The non-nitrogen-containing polymer (typically non-N-(meth)acryloyl type polymer) is not particularly limited, and for example, modified or unmodified polyvinyl alcohol-based polymers are preferably used. The nitrogen-containing polymer (typically N-(meth)acryloyl type polymer) used in combination with the above polyvinyl alcohol-based polymer is not particularly limited, and polymers containing cyclic amides having N-(meth)acryloyl groups as monomer units are preferred, with PACMO being more preferred. In an embodiment in which nitrogen atom-containing polymers and non-nitrogen atom-containing polymers are used in combination, the usage ratio (nitrogen atom-containing polymer:non-nitrogen atom-containing polymer) is not particularly limited and can be 1:9 to 9:1 by weight, 3:7 to 8:2, or 5:5 to 7:3.

[0079] In the technologies disclosed herein, the weight-average molecular weight (Mw) of the water-soluble polymer is not particularly limited. The Mw of the water-soluble polymer is, for example, approximately 200 × 10⁻⁶ 4 The following may be used, approximately 150 x 10 4 The following is suitable, and from the viewpoint of cleanability, it is preferably about 100 × 10 4 The following is approximately 50 x 10 4 The following may also be the case. Furthermore, from the viewpoint of protecting the polished surface, the Mw of the water-soluble polymer should be, for example, 0.2 × 10⁻⁶. 4 It may be greater than or equal to 0.5 × 10 4 Preferably, the above is true. In some embodiments, the above Mw is 1.0 × 10 4 The above is appropriate, 2 × 10 4 It may be greater than or equal to, for example, 5 × 104 That's fine too.

[0080] In the technologies disclosed herein, the preferred molecular weight range of the water-soluble polymer compounds may vary depending on the type of polymer used. For example, the Mw of cellulose derivatives and starch derivatives is approximately 200 × 10⁻⁶, respectively. 4 It can be as follows: 150 × 10 4 The following is appropriate. The above Mw is approximately 100 x 10 4 The following are also acceptable, approximately 50 x 10 4 (For example, approximately 30 x 10) 4 The following is also acceptable. Furthermore, from the viewpoint of protecting the polished surface, the above Mw should be, for example, approximately 0.2 × 10 4 That is all, approximately 0.5 × 10 4 It is appropriate for the above to be true, preferably about 1.0 × 10 4 More precisely, approximately 3.0 × 10 4 More preferably, approximately 10 × 10 4 That is all, approximately 20 × 10 4 That's fine too.

[0081] For example, the Mw of a polyvinyl alcohol-based polymer is 100 × 10 4 The following is possible: 60 x 10 4 The following is appropriate. From the viewpoint of concentration efficiency, etc., the above Mw is 30 × 10 4 The following may also be included, preferably 20 × 10 4 For example, 10 x 10 4 The following is a typical example of 8 × 10 4 The following is also acceptable: 5 × 10 4 The following is also acceptable: 3 x 10 4 The following is also acceptable. Furthermore, from the viewpoint of suitably protecting the polished surface and maintaining or improving surface quality, Mw may be, for example, 0.2 × 10 4 It may be greater than or equal to 0.5 × 10 4 Preferably, the above. In some embodiments, Mw is 0.8 × 10⁻⁶ 4 The above is appropriate, preferably 1.0 × 10 4 That's all. 2 × 10 4It may be the above, 3×10 4 It may also be the above, for example 4×10 4 It may also be the above, 5×10 4 It may be the above.

[0082] Also, for example, the Mw of a polymer containing a nitrogen atom (for example, an N-(meth)acryloyl type polymer, preferably PACMO) can be 100×10 4 or less, and 70×10 4 or less is appropriate. From the viewpoint of concentration efficiency and the like, the above Mw may be 60×10 4 or less, and 50×10 4 or less may also be possible. Also, from the viewpoint of maintaining or improving the surface quality, the Mw may be, for example, 1.0×10 4 or more, and 10×10 4 or more may also be possible. In some embodiments, the Mw is preferably 20×10 4 or more, preferably 30×10 4 or more, and may be, for example, 40×10 4 or more.

[0083] As the Mw of the water-soluble polymer, the molecular weight calculated from the value based on aqueous gel permeation chromatography (GPC) (aqueous system, polyethylene oxide conversion) can be adopted. As the GPC measuring device, it is preferable to use the model name "HLC-8320GPC" manufactured by Tosoh Corporation. The measurement can be performed, for example, under the following conditions. The same method is adopted for the examples described later. [GPC Measurement Conditions] Sample concentration: 0.1% by weight Column: TSKgel GMPWXL Detector: Differential refractometer Eluent: 100 mM sodium nitrate aqueous solution / acetonitrile = 10~8 / 0~2 Flow rate: 1 mL / min Measurement temperature: 40°C Sample injection volume: 200 μL

[0084] From the viewpoints of reducing aggregates and improving detergency, etc., a nonionic polymer can preferably be adopted as the water-soluble polymer. Further, from the viewpoints of easy control of chemical structure and purity, a synthetic polymer can preferably be adopted as the water-soluble polymer. For example, when the technology disclosed herein is implemented in an embodiment including a synthetic polymer as the water-soluble polymer, the polishing composition may not substantially use a polymer derived from a natural product as the water-soluble polymer. Here, not substantially using means that the amount of the polymer derived from a natural product with respect to 100 parts by weight of the total content of the water-soluble polymer is typically 3 parts by weight or less, preferably 1 part by weight or less, and includes 0 part by weight or below the detection limit.

[0085] The content (content based on weight) of the water-soluble polymer in the polishing composition is not particularly limited. For example, it can be 1.0×10 -4 wt% or more. From the viewpoint of haze reduction, etc., a preferable content is 5.0×10 -4 wt% or more, more preferably 1.0×10 -3 wt% or more, still more preferably 2.0×10 -3 wt% or more, for example 5.0×10 -3 wt% or more. Further, from the viewpoint of polishing rate, etc., it is preferable that the above content is 0.2 wt% or less, more preferably 0.1 wt% or less, and still more preferably 0.05 wt% or less (for example, 0.02 wt% or less, further 0.015 wt% or less). In addition, when the above polishing composition contains two or more kinds of water-soluble polymers, the above content means the total content (content based on weight) of all the water-soluble polymers contained in the polishing composition. These contents can be preferably applied, for example, to the content in the polishing liquid (working slurry) supplied to the substrate.

[0086] Furthermore, when the polishing composition disclosed herein contains abrasive grains, the content of water-soluble polymers (the total amount if two or more types of water-soluble polymers are included) can also be determined by its relative relationship to the abrasive grains. Although not particularly limited, in some embodiments, the content of water-soluble polymers per 100 parts by weight of abrasive grains can be, for example, 0.01 parts by weight or more, and from the viewpoint of haze reduction, etc., 0.1 parts by weight or more is appropriate, preferably 0.5 parts by weight or more, more preferably 1 part by weight or more, and even more preferably 3 parts by weight or more, and may be, for example, 4 parts by weight or more. Also, the content of water-soluble polymers per 100 parts by weight of abrasive grains may be, for example, 50 parts by weight or less, or 30 parts by weight or less. From the viewpoint of dispersion stability of the polishing composition, etc., in some embodiments, the content of water-soluble polymers per 100 parts by weight of abrasive grains can be, for example, 15 parts by weight or less, preferably 10 parts by weight or less, and may be 8 parts by weight or less, or 7 parts by weight or less.

[0087] (Optional surfactant B) The polishing compositions disclosed herein may further contain surfactant B (an optional surfactant) different from surfactant A, as needed, in addition to surfactant A. Surfactant B can be anionic, cationic, nonionic, or amphoteric. Usually, anionic or nonionic surfactant B is preferred. Nonionic surfactants are more preferred from the viewpoint 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 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 (e.g., polyoxyalkylene adducts); and copolymers of multiple types of oxyalkylenes (e.g., diblock copolymers, triblock copolymers, random copolymers, alternating copolymers). For example, surfactants containing a polyoxyalkylene structure can be used as surfactant B. Surfactant B can be used alone or in combination of two or more types.

[0088] 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 triblocks, 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, and Examples include polyoxyethylene oleyl ether, polyoxyethylene phenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene nonylphenyl ether, polyoxyethylene dodecylphenyl ether, polyoxyethylene styrene 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.

[0089] The weight-average molecular weight (Mws) of surfactant B is typically less than 2000, and is preferably 1900 or less (e.g., less than 1800) from the viewpoint of filterability and washing ability. Furthermore, the Mws of surfactant is usually appropriate to be 200 or more from the viewpoint of surface activity, and is preferably 250 or more (e.g., 300 or more) from the viewpoint of haze reduction effect. A more preferable range for the Mws of surfactant B may also vary depending on the type of surfactant B. For example, when polyoxyethylene alkyl ether is used as surfactant B, its Mws is preferably 1500 or less, and may be 1000 or less (e.g., 500 or less). Also, for example, when a PEO-PPO-PEO type triblock copolymer is used as surfactant B, its Mws may be, for example, 500 or more, may be 1000 or more, and may even be 1200 or more. The molecular weight of surfactant B can be the molecular weight calculated from the chemical formula, similar to surfactant A.

[0090] When the polishing composition disclosed herein contains surfactant B in addition to surfactant A, the content of surfactant B is appropriately set to be 10 times or less the content of surfactant A (for example, 0.01 times or more and 10 times or less), and may be, for example, 5 times or less the content of surfactant A, 1 time or less, or 0.1 times or less. The technology disclosed herein is preferably carried out in a manner in which the polishing composition substantially does not contain surfactant B. It should be noted that "substantially does not contain surfactant B" means that surfactant B is not included, at least intentionally.

[0091] <Other ingredients> The polishing compositions disclosed herein may further contain, as necessary, known additives that can be used in polishing compositions (for example, polishing compositions used in the finishing polishing process of silicon wafers), such as organic acids, organic acid salts, inorganic acids, inorganic acid salts, chelating agents, preservatives, and antifungal agents, to the extent that the effects of the present invention are not significantly hindered.

[0092] Organic acids and their salts, as well as inorganic acids and their salts, can be used individually or in combination of two or more. Examples of organic acids include fatty acids such as formic acid, acetic acid, and propionic acid; aromatic carboxylic acids such as benzoic acid and phthalic acid; itaconic acid, citric acid, oxalic acid, tartaric acid, malic acid, maleic acid, fumaric acid, succinic acid, glycolic acid, malonic acid, gluconic acid, alanine, glycine, lactic acid, organic sulfonic acids such as hydroxyethylidene diphosphate (HEDP) and methanesulfonic acid; and organic phosphonic acids such as nitrilotris (methylene phosphate) (NTMP) and phosphonovutanetricarboxylic acid (PBTC). Examples of organic acid salts include alkali metal salts (sodium salts, potassium salts, etc.) and ammonium salts of organic acids. Examples of inorganic acids include hydrochloric acid, phosphoric acid, sulfuric acid, phosphonic acid, nitric acid, phosphinic acid, boric acid, and carbonic acid. Examples of inorganic acid salts include alkali metal salts (sodium salts, potassium salts, etc.) and ammonium salts of inorganic acids.

[0093] The above chelating agents may be used individually or in combination of two or more. Examples of the above chelating agents include aminocarboxylic acid-based chelating agents and organic phosphonic acid-based chelating agents. Preferred examples of chelating agents include, for example, ethylenediaminetetrakis(methylenephosphonic acid), diethylenetriaminepenta(methylenephosphonic acid), and diethylenetriaminepentaacetic acid. Examples of the above preservatives and fungicides include isothiazolinoline compounds, parahydroxybenzoic acid esters, phenoxyethanol, etc.

[0094] The polishing compositions disclosed herein preferably contain substantially no oxidizing agents. This is because if an oxidizing agent is present in the polishing composition, when the polishing composition is supplied to a substrate (e.g., a silicon wafer), the surface of the substrate may be oxidized, forming an oxide film, which may reduce the polishing rate. Specific examples of oxidizing agents include hydrogen peroxide (H2O2), sodium persulfate, ammonium persulfate, and sodium dichloroisocyanurate. It should be noted that a polishing composition that contains substantially no oxidizing agents means that it does not contain oxidizing agents at least intentionally. Therefore, a polishing composition that inevitably contains trace amounts of oxidizing agents (for example, a molar concentration of oxidizing agents 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, particularly preferably 0.000001 mol / L or less) due to raw materials or manufacturing methods may be included in the concept of a polishing composition that contains substantially no oxidizing agents as described herein.

[0095] <ph> The pH of the polishing composition disclosed herein is not particularly limited, and an appropriate pH can be adopted depending on the substrate and, if abrasive grains are included, the type of abrasive grains. In some embodiments, the pH of the polishing composition is suitable at 8.0 or higher, preferably 8.5 or higher, and more preferably 9.0 or higher. As the pH of the polishing composition increases, the polishing rate tends to improve. On the other hand, in embodiments in which the polishing composition includes abrasive grains, for example, from the viewpoint of preventing the dissolution of the abrasive grains (e.g., silica particles) and suppressing a decrease in mechanical polishing action, the pH of the polishing composition is usually suitable at 12.0 or lower, preferably 11.0 or lower, more preferably 10.8 or lower, and even more preferably 10.5 or lower.

[0096] In the technology disclosed herein, the pH of the polishing composition can be determined by using a pH meter (for example, a glass electrode type hydrogen ion concentration indicator (model number F-72) manufactured by Horiba, Ltd.), performing a three-point calibration using standard buffers (phthalate pH buffer pH: 4.01 (25°C), neutral phosphate pH buffer pH: 6.86 (25°C), carbonate pH buffer pH: 10.01 (25°C)), then placing the glass electrode into the composition to be measured and measuring the value after it has stabilized for two minutes or more.

[0097] <Polishing liquid> The polishing compositions disclosed herein are typically supplied onto the surface of a substrate in the form of a polishing solution containing the polishing composition and used to polish the substrate. The polishing solution may be prepared, for example, by diluting (typically with water) one of the polishing compositions disclosed herein. Alternatively, the polishing composition may be used as is as a polishing solution. That is, the concept of a polishing composition in the art disclosed herein encompasses both a polishing solution (working slurry) supplied to a substrate and used to polish the substrate, and a concentrated solution (stock polishing solution) that is diluted and used as a polishing solution. Another example of a polishing solution containing the polishing compositions disclosed herein is a polishing solution obtained by adjusting the pH of the composition.

[0098] <Concentrate> The polishing composition disclosed herein may be in a concentrated form (i.e., in the form of a concentrated polishing solution) before being supplied to the substrate. Such a concentrated form of the polishing composition is advantageous in terms of convenience and cost reduction during manufacturing, distribution, and storage. The concentration ratio is not particularly limited and can be, for example, 2 to 100 times in terms of volume, and is usually appropriate at around 5 to 50 times (for example, 10 to 40 times). Such a concentrated solution can be used by diluting it at a desired timing to prepare a polishing solution (working slurry), and then supplying the polishing solution to the substrate. The dilution can be performed, for example, by adding water to the concentrated solution and mixing it.

[0099] Furthermore, in embodiments where the polishing composition contains abrasive grains, when the polishing composition (i.e., concentrated liquid) is diluted and used for polishing, the abrasive grain content in the concentrated liquid can be, for example, 25% by weight or less. From the viewpoint of dispersion stability and filterability of the polishing composition, the above content is usually preferably 20% by weight or less, and more preferably 15% by weight or less. In one preferred embodiment, the abrasive grain content may be 10% by weight or less, or 5% by weight or less. Also, from the viewpoint of convenience and cost reduction during manufacturing, distribution, storage, etc., the abrasive grain content in the concentrated liquid 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.

[0100] <Preparation of polishing composition> The abrasive compositions used in the technologies disclosed herein may be mono-component or multi-component, including two-component types. For example, in embodiments in which the abrasive composition contains abrasive grains, the abrasive solution may be prepared by mixing part A, which contains at least abrasive grains from the components of the abrasive composition, and part B, which contains at least a portion of the remaining components, and mixing and diluting these at appropriate times as needed.

[0101] 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 vane-type stirrer, an ultrasonic disperser, or a homomixer. The manner in which these components are mixed is not particularly limited; for example, all components may be mixed at once, or they may be mixed in an order set as appropriate.

[0102] <Application> The polishing compositions disclosed herein can be applied to polishing substrates having various materials and shapes. Substrate materials may include, for example, metals or metalloids 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. A substrate may also be composed of multiple of these materials. The shape of the substrate is not particularly limited. The polishing compositions disclosed herein can be applied, for example, to polish substrates having flat surfaces, such as plate-shaped or polyhedral substrates, or to polish the edges of substrates (e.g., wafer edge polishing).

[0103] The polishing compositions disclosed herein may be particularly preferred for polishing silicon surfaces (typically silicon wafers). Typical examples of silicon wafers are silicon single-crystal wafers, such as silicon single-crystal wafers obtained by slicing a silicon single-crystal ingot.

[0104] The polishing compositions disclosed herein can be preferably applied to a polishing process of a substrate (e.g., a silicon wafer). The substrate may have undergone general treatments that can be applied to the substrate in an upstream process, such as lapping or etching, prior to the polishing process with the polishing compositions disclosed herein.

[0105] The polishing compositions disclosed herein are effective when used in a finishing process of a substrate (e.g., a silicon wafer) or in a polishing process immediately preceding it, and are particularly preferred for use in a finishing polishing process. Here, a finishing polishing process refers to the final polishing process in the manufacturing process of the object (i.e., a process after which no further polishing is performed). The polishing compositions disclosed herein may also be used in polishing processes upstream of finishing polishing (referring to a preliminary polishing process between a rough polishing process and a final polishing process, which typically includes at least a primary polishing process and may further include secondary, tertiary, etc. polishing processes), for example, in a polishing process performed immediately before finishing polishing.

[0106] The polishing compositions disclosed herein are effective, for example, for polishing silicon wafers that have been prepared by an upstream process to a surface roughness of 0.01 nm to 100 nm (typically for finish polishing or polishing immediately preceding it). Application to finish polishing is particularly preferred. The surface roughness Ra of the substrate can be measured, for example, using a laser scanning surface roughness meter "TMS-3000WRC" manufactured by Schmitt Measurement System Inc.

[0107] <Polishing> The polishing compositions disclosed herein can be used for polishing substrates in embodiments including, for example, the following operations. A preferred embodiment of a method for polishing a silicon wafer as a substrate using the polishing compositions disclosed herein will be described below. In other words, a polishing solution containing one of the polishing compositions disclosed herein is prepared. Preparing the polishing solution may involve adjusting the concentration (e.g., dilution) or pH of the polishing composition to prepare the polishing solution. Alternatively, the polishing composition may be used as is as a polishing solution.

[0108] Next, the polishing solution is supplied to the substrate and polished using a conventional method. For example, when performing final polishing of a silicon wafer, typically, the silicon wafer that has undergone the lapping process is set in a general polishing apparatus, and the polishing solution is supplied to the surface of the silicon wafer to be polished through the polishing pad of the apparatus. Typically, while continuously supplying the polishing solution, the polishing pad is pressed against the surface of the silicon wafer to be polished and the two are moved relative to each other (for example, by rotation). Through this polishing process, the polishing of the substrate is completed.

[0109] The polishing pad used in the above polishing process is not particularly limited. For example, polishing pads of foamed polyurethane type, nonwoven fabric type, suede type, etc., can be used. Each polishing pad may or may not contain abrasive grains. Generally, polishing pads that do not contain abrasive grains are preferred.

[0110] A substrate polished using the polishing composition disclosed herein is typically cleaned. Cleaning can be performed using a suitable cleaning solution. The cleaning solution used is not particularly limited, and for example, SC-1 cleaning solution (a mixture of ammonium hydroxide (NH4OH), hydrogen peroxide (H2O2), and water (H2O)), SC-2 cleaning solution (a mixture of HCl, H2O2, and H2O), which are common in fields such as semiconductors, can be used. The temperature of the cleaning solution can be, for example, in the range of room temperature (typically about 15°C to 25°C) or up 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.

[0111] As described above, the technologies disclosed herein may 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 a polished product (e.g., a silicon wafer) manufactured by said method. [Examples]

[0112] The following describes several embodiments of the present invention, but the present invention is not intended to be limited to those shown in these embodiments. In the following description, "%" refers to weight unless otherwise specified.

[0113] <Preparation of polishing composition> (Example 1) A concentrated solution of the polishing composition according to this example was prepared by mixing abrasive grains, a surfactant, a water-soluble polymer, a basic compound, and deionized water. Colloidal silica (average primary particle size: 27 nm) was used as the abrasive grains. The surfactant was R of formula (1) above. 1 and R 4 Both are iso-butyl groups, R 2 and R 3 A compound was used in which both groups are methyl groups, the average number of added moles is 10, and the molecular weight is approximately 666. As a water-soluble polymer, a compound with a weight-average molecular weight (Mw) of approximately 1.0 × 10⁶ was used. 4 Acetalized polyvinyl alcohol (ac-PVA) was used. Ammonia was used as the basic compound. By diluting the concentrated solution of the obtained polishing composition with deionized water at a volume ratio of 20, a polishing composition according to this example was obtained with a concentration of abrasive particles of 0.175%, a concentration of surfactant of 0.00015%, a concentration of water-soluble polymer of 0.005%, and a concentration of basic compound of 0.005%.

[0114] (Example 2) As a surfactant, R in the above formula (1) 1 and R 4 Both are iso-butyl groups, R 2 and R 3 The polishing composition according to this example was prepared in the same manner as in Example 1, except that a compound was used in which both groups were methyl groups, the average number of added moles was 30, and the molecular weight was approximately 1540.

[0115] (Comparative Example 1) The polishing composition according to this example was prepared in the same manner as in Example 1, except that polyoxyethylene decyl ether (C10EO5) with 5 moles of ethylene oxide added was used as the surfactant. The surfactant used in this example is a compound with a molecular weight of 378.

[0116] (Example 3) A concentrated solution of the polishing composition according to this example was prepared by mixing abrasive grains, a surfactant, a water-soluble polymer, a basic compound, and deionized water. Colloidal silica (average primary particle size: 27 nm) was used as the abrasive grains. The compound used in Example 2 was used as the surfactant. The water-soluble polymer had an Mw of approximately 2.5 × 10 5 Hydroxyethylcellulose (HEC) was used. Ammonia was used as the basic compound. By diluting the concentrated solution of the obtained polishing composition with deionized water at a volume ratio of 20, a polishing composition according to this example was obtained with a concentration of abrasive particles of 0.175%, a concentration of surfactant of 0.00015%, a concentration of HEC of 0.009%, and a concentration of basic compound of 0.005%.

[0117] (Comparative Example 2) The polishing composition according to this example was prepared in the same manner as in Example 3, except that polyoxyethylene decyl ether (C10EO5) with 5 moles of ethylene oxide added, as used in Comparative Example 1, was used as the surfactant.

[0118] (Example 4) A concentrated solution of the polishing composition according to this example was prepared by mixing abrasive grains, a surfactant, a water-soluble polymer, a basic compound, and deionized water. Colloidal silica (average primary particle size: 27 nm) was used as the abrasive grains. The surfactant was R of formula (1) above. 1 and R 4 Both are iso-butyl groups, R 2 and R 3 A compound was used in which both groups are methyl groups, the average number of added moles is 1.3, and the molecular weight is approximately 283. As for the water-soluble polymer, Mw is approximately 4.7 × 10⁻⁶. 5 The polyacryloylmorpholine (PACMO) and Mw are approximately 1.0 × 10⁻⁶ 4 Acetalized polyvinyl alcohol (ac-PVA) was used. Ammonia was used as the basic compound. By diluting the concentrated solution of the obtained polishing composition with deionized water at a volume ratio of 20, a polishing composition according to this example was obtained with a concentration of abrasive particles of 0.169%, a concentration of surfactant of 0.00015%, a concentration of PACMO of 0.0083%, a concentration of ac-PVA of 0.005%, and a concentration of basic compound of 0.005%.

[0119] (Example 5) As a surfactant, R in the above formula (1) 1 and R 4 Both are iso-butyl groups, R 2 and R 3 The polishing composition according to this example was prepared in the same manner as in Example 4, except that a compound was used in which both groups were methyl groups, the average number of added moles was 3.5, and the molecular weight was approximately 380.

[0120] (Example 6) The polishing composition according to this example was prepared in the same manner as in Example 4, except that the compound used in Example 1 was used as the surfactant.

[0121] (Example 7) The polishing composition according to this example was prepared in the same manner as in Example 4, except that the compound used in Example 2 was used as the surfactant.

[0122] (Example 8) The polishing composition according to this example was prepared in the same manner as in Example 7, except that the concentration of the surfactant was set to 0.0003%.

[0123] (Comparative Example 3) The polishing compositions for each example were prepared in the same manner as in Example 4, except that polyoxyethylene decyl ether (C10EO5) with 5 moles of ethylene oxide added, as used in Comparative Example 1, was used as the surfactant, and its concentration was set to 0.005%.

[0124] <Polishing silicon wafers> As the substrate, a commercially available 200mm diameter silicon single crystal wafer (conduction type: P-type, crystal orientation: <100> A silicon wafer was prepared by pre-polishing a COP (Crystal Originated Particle: crystal defect-free) wafer according to the following polishing condition 1. Pre-polishing was performed using a polishing solution containing 1.0% abrasive particles (colloidal silica with an average primary particle size of 42 nm) and 0.068% potassium hydroxide in deionized water.

[0125] [Polishing conditions 1] Polishing equipment: Single-wafer polishing machine, model "PNX-322", manufactured by Okamoto Machine Tool Works, Ltd. Grinding load: 15kPa Plate rotation speed: 30 rpm Head (carrier) rotation speed: 30 rpm Polishing pad: Manufactured by Fujibo Ehime Co., Ltd. Product name: "FP55" Pre-polishing solution supply rate: 550 mL / min Pre-polishing solution temperature: 20℃ Temperature of cooling water in the surface plate: 20℃ Polishing time: 3min

[0126] The polishing compositions prepared in each of the above examples were used as polishing solutions, and the silicon wafers after the preliminary polishing were polished under the following polishing conditions 2.

[0127] [Polishing conditions 2] Polishing equipment: Single-wafer polishing machine, model "PNX-322", manufactured by Okamoto Machine Tool Works, Ltd. Grinding load: 15kPa Plate rotation speed: 30 rpm Head (carrier) rotation speed: 30 rpm Polishing pad: Manufactured by Fujibo Ehime Co., Ltd. Product name: "POLYPAS275NX(RB)" Polishing solution supply rate: 400 mL / min Polishing solution temperature: 20℃ Temperature of cooling water in the surface plate: 20℃ Polishing time: 4 min

[0128] After polishing, the silicon wafers were removed from the polishing apparatus and cleaned using a cleaning solution of NH4OH (29%):H2O2 (31%):deionized water (DIW) = 1:1:12 (volume ratio) (SC-1 cleaning). Specifically, two cleaning tanks, the first and second, were prepared, and the above cleaning solution was placed in each of these tanks and maintained at 60°C. The polished silicon wafers were immersed in the first cleaning tank for 5 minutes, then immersed in ultrapure water and subjected to ultrasonic waves in a rinsing tank, then immersed in the second cleaning tank for 5 minutes, then immersed in ultrapure water and subjected to ultrasonic waves in a rinsing tank, and finally dried using a spin dryer.

[0129] <Haze Measurement> The surface of the silicon wafer after cleaning 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 the following method. The obtained results are shown in Table 1, converted to a relative value (haze ratio) with the haze value of Comparative Example 1 set to 100%, in Table 2, converted to a relative value (haze ratio) with the haze value of Comparative Example 2 set to 100%, and in Table 3, converted to a relative value (haze ratio) with the haze value of Comparative Example 3 set to 100%. A smaller haze ratio indicates a higher haze improvement effect. Furthermore, since the comparison surfactant (C10EO5) also has a certain haze improvement effect, those showing a haze ratio of 105 or less on a relative value basis compared to Comparative Examples 1, 2, and 3 containing the surfactant (C10EO5) are judged to have maintained or improved haze values.

[0130] <Polishing speed> The object to be polished is a 200mm diameter silicon wafer (conduction type: P-type, crystal orientation: <100> A COP (Crystal Originated Particle)-free sample was prepared and immersed in an HF aqueous solution (HF concentration: 2%) for 60 seconds to remove the oxide film. The polishing composition for each example was then used as the polishing solution and polished under the following polishing conditions 3.

[0131] [Polishing conditions 3] Polishing equipment: Single-wafer polishing machine, model "PNX-322", manufactured by Okamoto Machine Tool Works, Ltd. Grinding load: 15kPa Plate rotation speed: 30 rpm Head (carrier) rotation speed: 30 rpm Polishing pad: Manufactured by Fujibo Ehime Co., Ltd. Product name: "POLYPAS275NX(RB)" Polishing solution supply rate: 400 mL / min Polishing solution temperature: 20℃ Temperature of cooling water in the surface plate: 20℃ Polishing time: 10min

[0132] After polishing, the silicon wafers were removed from the polishing apparatus and immersed in a cleaning solution of NH4OH (29%):H2O2 (31%):deionized water = 1:1:12 (volume ratio) for 5 minutes to clean them (SC-1 cleaning). Subsequently, they were immersed in deionized water with the ultrasonic oscillator running and dried using a spin dryer.

[0133] (evaluation) The weight of the silicon wafers before and after polishing was measured, and the polishing rate [nm / min] was determined from the weight difference and the specific gravity of silicon. The results obtained are shown in Table 1, Table 2, and Table 3, respectively, converted to relative values ​​with the polishing rate of Comparative Example 1 set to 100%. A higher value indicates a higher polishing rate.

[0134] [Table 1]

[0135] [Table 2]

[0136] [Table 3]

[0137] As shown in Tables 1 and 2, polishing using the polishing compositions of Examples 1 to 3, which contain the surfactant compound represented by formula (1) above, showed a tendency for the polishing speed to improve while maintaining or improving the haze value within a predetermined range (relative value of 105% or less) compared to Comparative Examples 1 and 2, which do not contain the surfactant of the specific structure. Furthermore, as shown in Table 3, polishing using the polishing compositions of Examples 4 to 8, which contain the surfactant compound represented by formula (1) above, showed a tendency for the polishing speed to improve while maintaining or improving the haze value within a predetermined range (relative value of 105% or less) compared to Comparative Example 3, which does not contain the surfactant of the specific structure. From the above results, it can be seen that a composition suitable for polishing can be prepared by using a surfactant, which is a compound represented by formula (1) above.

[0138] Although specific examples of the present invention have been described in detail above, these are merely illustrative and do not limit the scope of the claims. The technologies described in the claims include various modifications and changes to the specific examples illustrated above.< / ph>

Claims

1. It contains a basic compound, a surfactant, water, and a water-soluble polymer. The water-soluble polymer is one or more selected from the group consisting of modified polyvinyl alcohol, cellulose derivatives, and polymers containing nitrogen atoms. A polishing composition for silicon wafers, wherein the surfactant is a compound represented by the following formula (1). 【Chemistry 1】 (In formula (1), R １ ~R ４ Each is independently a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, R ５ , R ６ Each of these is independently a substituted or unsubstituted alkylene group having 1 to 5 carbon atoms, m is an integer greater than or equal to 1, n is an integer greater than or equal to 0, and m + n ≤ 50.

2. A basic compound, a surfactant, and water, A silicon wafer polishing composition wherein the surfactant is a compound represented by the following formula (1) and has a molecular weight of 300 or more. 【Chemistry 2】 (In formula (1), R1 to R4 are each independently a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, R5 and R6 are each independently a substituted or unsubstituted alkylene group having 1 to 5 carbon atoms, m is an integer of 1 or more, n is an integer of 0 or more, and m + n ≤ 50.)

3. The silicon wafer polishing composition according to claim 2, wherein m and n in formula (1) satisfy 15 ≤ m + n ≤ 50.

4. The silicon wafer polishing composition according to claim 2 or 3, further comprising a water-soluble polymer.

5. The polishing composition for silicon wafers according to any one of claims 1 to 4, further comprising abrasive particles.

6. The abrasive composition for silicon wafers according to claim 5, comprising silica particles as the abrasive grains.

7. The polishing composition for silicon wafers according to any one of claims 1 to 6, wherein the pH of the polishing composition is 8.0 or more and 12.0 or less.

8. A method for polishing a silicon wafer, comprising the step of polishing a silicon wafer using a silicon wafer polishing composition according to any one of claims 1 to 7.

9. A concentrated solution of the silicon wafer polishing composition according to any one of claims 1 to 7.

Images