Polishing composition and polishing method

Abstract

Provided is a polishing composition which, in a composition containing a cellulose derivative, can maintain low haze and has excellent defect reduction properties. The present invention can provide a polishing composition containing a cellulose derivative and a basic compound. The weight-average molecular weight (Mw) of the cellulose derivative is less than 80,000.

Description

Technical Field

[0001] This invention relates to a grinding composition and a grinding method.

[0002] This application claims priority based on Japanese Patent Application No. 2023-160704, filed on September 25, 2023, the contents of which are incorporated herein by reference. Background Technology

[0003] For the surfaces of materials such as metals, semi-metals, non-metals, and their oxides, abrasive compositions are used for precision grinding. For example, the surface of silicon wafers used as components of semiconductor devices is generally finished into a high-quality mirror surface through a grinding step (rough grinding step) and a polishing step (precision grinding step). The polishing step typically includes a pre-grinding step and a fine grinding step (final grinding step). Patent documents 1 and 2 are cited as examples of technical documents related to abrasive compositions primarily used for grinding semiconductor substrates such as silicon wafers.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2021-95431

[0007] Patent Document 2: Japanese Patent Application Publication No. 2011-61089 Summary of the Invention

[0008] The problem the invention aims to solve

[0009] Polishing compositions used for polishing semiconductor substrates such as silicon wafers and other substrates (e.g., polishing compositions used in fine polishing steps) need to achieve a surface with low haze and few surface defects after polishing. Such polishing compositions, in addition to water, also contain water-soluble polymers to protect the surface of the object being polished or to improve wettability. Cellulose derivatives are a common example of such water-soluble polymers.

[0010] In grinding compositions, cellulose derivatives are useful as components that improve surface quality; however, since they are made from natural cellulose, their quality is prone to deviation. Therefore, in grinding compositions containing cellulose derivatives, tiny aggregates that can cause surface defects may form. Furthermore, commonly used cellulose derivatives have relatively large molecular weights. For example, Patent Document 1 describes a conventional cellulose derivative as hydroxyethyl cellulose (HEC) with a weight-average molecular weight (Mw) of 250,000. In grinding compositions containing such cellulose derivatives, surfactants are used to improve the dispersibility of the cellulose derivatives, or aggregates are removed by filtration.

[0011] However, while cellulose derivatives with larger molecular weights are advantageous from the viewpoint of protecting the surface of the grinding object, they tend to have poor flowability in filters with small pore sizes, which can limit their ability to remove aggregates. For example, Patent Document 1 describes improving the filterability and reducing defects of a grinding composition by using HEC with a molecular weight of 120,000 and a specific type of surfactant.

[0012] Furthermore, Patent Document 2 discloses a polishing composition containing HEC hydrolysates with a Mw of 80,000, 330,000, 530,000, or 1,070,000, prepared by hydrolyzing HEC with a Mw of 300,000 to 3,000,000. Patent Document 2 describes how, by preferentially hydrolyzing the low-crystallinity portion of HEC, the sites that interact with the silicon wafer are selectively exposed to the molecular surface, resulting in good wettability on the silicon wafer surface during polishing and reducing residues on the wafer surface that may cause defects during rinsing (paragraph 0011).

[0013] As mentioned above, there are occasional studies of HECs with molecular weights smaller than those of general-purpose HECs in the prior art. However, in terms of practical applications, the research on low molecular weight HECs still remains in the region of Mw 80,000 and above, as described in Patent Document 2, considering that the use of surfactants can achieve the same suppression of aggregation and reduction of defects as HECs with Mw 280,000 and Mw 90,000 (refer to the comparative results of Comparative Examples 2 and 4 described later), as well as the grinding effect obtained based on molecular weight (increased grinding rate, reduced haze, etc.).

[0014] Incidentally, the requirements for the surface quality after grinding are increasing year by year, and the reduction of surface defects is also required to a higher level than before. If such a high level of defect reduction can be achieved by adding cellulose derivatives without relying on surfactants or other additives, then the design of the grinding composition offers a high degree of freedom and is ideal. Against this technical background, the inventors have repeatedly conducted research and, as a result, successfully obtained a grinding composition that maintains low haze and exhibits excellent defect reduction by using cellulose derivatives in a low molecular weight region that had not been previously studied, thus completing this invention. In other words, the object of this invention is to provide a grinding composition and a grinding method using this grinding composition, which, in its composition containing cellulose derivatives, maintains low haze and exhibits excellent defect reduction.

[0015] Solution for solving the problem

[0016] According to this specification, a grinding composition containing a cellulose derivative and an alkaline compound can be provided. Furthermore, the weight-average molecular weight (Mw) of the aforementioned cellulose derivative is less than 80,000. Based on the above-mentioned grinding composition, low haze can be maintained, while excellent defect reduction can be achieved.

[0017] In some embodiments, the weight-average molecular weight of the aforementioned cellulose derivative is 4,000 or more and less than 80,000. The techniques disclosed herein can be preferably implemented by using cellulose derivatives with a molecular weight (Mw) within the aforementioned range.

[0018] In some embodiments, the polishing composition further contains abrasive grains. A good polishing rate can be easily obtained with a polishing composition containing abrasive grains. Furthermore, according to the technology disclosed herein, excellent defect reduction can be achieved in the abrasive grain-containing embodiment. The abrasive grains are preferably colloidal silica with an average primary particle size of 20 nm or more and 50 nm or less. Colloidal silica having the above-mentioned average primary particle size is suitable for polishing compositions for the finishing of semiconductor substrates such as silicon wafers, but is not particularly limited thereto.

[0019] The grinding composition disclosed herein is preferably used for grinding surfaces formed of silicon material. By using the above-described grinding composition to grind surfaces formed of silicon material, high-quality surfaces formed of silicon material with greatly reduced defects can be achieved.

[0020] The grinding composition disclosed herein can be a concentrate. The grinding composition disclosed herein can be manufactured, transported, and stored as a concentrate.

[0021] In some embodiments, a polishing method may be provided, which includes the step of polishing a surface formed of silicon material using the above-described polishing composition. According to the above-described polishing method, a high-quality surface formed of silicon material with significantly reduced defects can be achieved.

[0022] Additionally, according to this specification, a rinsing composition containing a cellulose derivative is available. The weight-average molecular weight (Mw) of the aforementioned cellulose derivative is less than 80,000. The aforementioned rinsing composition can be used, for example, in a rinsing step after grinding. Detailed Implementation

[0023] The following describes suitable embodiments of the present invention. Furthermore, matters not specifically mentioned in this specification but essential for carrying out the invention can be learned by those skilled in the art based on prior art design considerations. The present invention can be implemented based on the disclosures in this specification and common technical knowledge in the field.

[0024] <Cellulose Derivatives (A)>

[0025] The grinding composition disclosed herein contains a cellulose derivative (hereinafter also referred to as cellulose derivative (A)) with a weight-average molecular weight (Mw) of less than 80,000. Here, cellulose derivative refers to a substance in which some of the hydroxyl groups of cellulose are replaced by other substituents. Specifically, the cellulose derivative contains β-glucose units as the main repeating units. By using the cellulose derivative, a low haze value can be obtained. Furthermore, by using a cellulose derivative with a Mw of less than 80,000, a low haze value can be maintained, and excellent defect reduction can be achieved. In addition, the grinding composition containing a cellulose derivative with a small Mw exhibits good and efficient flow permeability even for filters with small pore sizes; therefore, when used in filters with small pore sizes, aggregates that could cause defects can be effectively removed. Furthermore, due to the good flow permeability of the grinding composition, filter clogging is suppressed, and filter life is improved.

[0026] Specific examples of cellulose derivatives include hydroxyethyl cellulose (HEC), hydroxypropyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, ethyl cellulose, ethyl hydroxyethyl cellulose, and carboxymethyl cellulose. A single cellulose derivative can be used, or two or more can be used in combination. From the viewpoint of improving the surface quality after polishing, hydroxyethyl cellulose (HEC) is preferred among the aforementioned cellulose derivatives.

[0027] The Mw of the aforementioned cellulose derivative (A) is less than 80,000 (specifically less than 80,000). From the viewpoint of defect reduction, in some embodiments, it may be less than 70,000, less than 60,000, or less than 50,000. In some preferred embodiments, the Mw of the aforementioned cellulose derivative (A) is less than 50,000, more preferably less than 40,000, even more preferably less than 30,000, even more preferably less than 20,000, and particularly preferably less than 10,000 (e.g., less than 10,000, more specifically, for example, less than 9,000). Since the grinding composition containing a cellulose derivative with an Mw limited to the above range exhibits highly efficient liquid permeability even when used with a filter with a small pore size, it can better remove aggregates that may cause defects, and achieves superior defect reduction. The lower limit of the Mw of the aforementioned cellulose derivative (A) is not particularly limited. From the viewpoint of improving the protection or grinding performance of the surface being ground, in some cases it may be 1,000 or more, 2,000 or more, 4,000 or more, 5,000 or more, or 6,000 or more. In other cases, the Mw of the aforementioned cellulose derivative (A) may be 10,000 or more (e.g., exceeding 10,000), 15,000 or more, or 30,000 or more.

[0028] In this specification, the Mw of the cellulose derivative (A) can be expressed as a value obtained by gel permeation chromatography (GPC) (converted to aqueous or polyethylene oxide). The GPC measuring apparatus can be the HLC-8320GPC manufactured by Tosoh Corporation. The measurement conditions are as described below. The same method can also be used in the examples described later.

[0029] [GPC Measurement Conditions]

[0030] Sample concentration: 0.1% by weight

[0031] Column: TSKgel GMPWXL

[0032] Detector: Differential refractometer

[0033] Eluent: 0.1 mol / L NaNO3 aqueous solution

[0034] Flow rate: 1.0 mL / min

[0035] Measurement temperature: 40℃

[0036] Sample injection volume: 200 μL

[0037] The aforementioned cellulose derivative (A) can be synthesized, for example, by known or conventional methods, such as by reducing the molecular weight of a relatively high-molecular-weight cellulose derivative using appropriate methods and conditions from known or conventional molecular weight reduction treatments. Sometimes, obtaining the cellulose derivative via the aforementioned molecular weight reduction is preferred. For example, for commercially available cellulose derivatives, by performing one or more molecular weight reduction treatments selected from pressure decomposition, pyrolysis, shearing treatment, enzymatic hydrolysis, electrolysis, and radioactive decomposition under appropriate conditions (treatment time, etc.), a cellulose derivative (A) with a target molecular weight can be obtained.

[0038] <Alkaline compounds>

[0039] The grinding composition disclosed herein contains an alkaline compound. In this specification, an alkaline compound refers to a compound that, when dissolved in water, raises the pH of the aqueous solution. By including an alkaline compound in the grinding composition, the workpiece can be effectively ground through its chemical grinding action (alkaline etching). As an alkaline compound, nitrogen-containing organic or inorganic alkaline compounds, alkali metal hydroxides, alkaline earth metal hydroxides, quaternary phosphorus compounds, various carbonates or bicarbonates, etc., can be used. Examples of nitrogen-containing alkaline compounds include quaternary ammonium compounds, ammonia, and amines (preferably water-soluble amines). Such alkaline compounds can be used alone or in combination of two or more.

[0040] Among these basic compounds, at least one basic compound selected from alkali metal hydroxides, quaternary ammonium hydroxides, and ammonia is preferred. Potassium hydroxide, tetraalkylammonium hydroxide (e.g., tetramethylammonium hydroxide), and ammonia are particularly preferred.

[0041] <Water>

[0042] The grinding composition disclosed herein typically contains water. The water used in the grinding composition is preferably ion-exchanged water (deionized water), pure water, ultrapure water, distilled water, etc. To minimize interference with the function of other components in the grinding composition, the total content of transition metal ions is preferably 100 ppb or less. The purity of the water can be improved, for example, by removing impurity ions using ion exchange resins, removing foreign matter using filters, distillation, etc. It should be noted that the grinding composition disclosed herein may further contain an organic solvent (lower alcohols, lower ketones, etc.) that is homogeneous with water, as needed. The solvent contained in the grinding composition is preferably 90% by volume or more water, more preferably 95% by volume or more (e.g., 99-100% by volume) water.

[0043] Abrasive grains

[0044] In some methods, the abrasive composition preferably contains abrasive grains. The abrasive grains contribute to increasing the abrasive rate by mechanically grinding the surface of the object being abraded. The material or properties of the abrasive grains are not particularly limited and can be appropriately selected according to the intended use and method of application of the abrasive composition. Specific 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 hematite 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 to the inclusion of both acrylic acid and methacrylic acid), and polyacrylonitrile particles. Such abrasive grains can be used alone or in combination of two or more.

[0045] As the aforementioned abrasive grains, inorganic particles are preferred, particularly particles formed from oxides of metals or semi-metals, and especially silicon dioxide particles. It is particularly meaningful to use silicon dioxide particles as abrasive grains in abrasive compositions used for polishing (e.g., fine polishing) objects having surfaces formed of silicon, such as silicon wafers, as described later. The technology disclosed herein can be preferably implemented in a manner where, for example, the abrasive grains described above are substantially formed of silicon dioxide particles. Here, "substantially" means that 95% by weight or more (preferably 98% by weight or more, more preferably 99% by weight or more, or possibly 100% by weight) of the particles constituting the abrasive grains are silicon dioxide particles.

[0046] Specific examples of silica particles include colloidal silica, fumed silica, and precipitated silica. Silica particles can be used alone or in combination of two or more types. From the viewpoint of easily obtaining a polished surface with excellent quality after grinding, colloidal silica is particularly preferred. As colloidal silica, colloidal silica produced by ion exchange using water glass (sodium silicate) as a raw material is preferred, for example, or alkoxide-based colloidal silica (colloidal silica produced by the hydrolysis and condensation reaction of alkoxysilanes). Colloidal silica can be used alone or in combination of two or more types.

[0047] The true specific gravity of the silica constituting the 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 the silica is not particularly limited, but is typically 2.3 or less, for example, 2.2 or less. The true specific gravity of the silica particles can be determined by a liquid displacement method using ethanol as the displacement solution.

[0048] The average primary particle size of the abrasive grains (typically silica particles, preferably colloidal silica) is not particularly limited, but from the viewpoint of grinding rate, it is preferably 5 nm or more, more preferably 10 nm or more. From the viewpoint of obtaining higher grinding effects (e.g., reducing haze, removing defects, etc.), in some embodiments, the aforementioned average primary particle size is preferably 15 nm or more, more preferably 20 nm or more (e.g., more than 20 nm), even more preferably 25 nm or more, even more preferably 28 nm or more, particularly preferably 30 nm or more, and may also be 32 nm or more. In addition, from the viewpoint of preventing scratches, the average primary particle size 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 easily obtaining a surface with lower haze, in some embodiments, the average primary particle size of the abrasive grains is preferably 43 nm or less, more preferably 40 nm or less (e.g., less than 40 nm), and may also be less than 38 nm.

[0049] It should be noted that, in this specification, the average primary particle size refers to the specific surface area (BET value) measured by the BET method, calculated according to the formula: average primary particle size (nm) = 6000 / (true density (g / cm³)). 3 )×BET value (m 2 The particle size (BET particle size) is calculated using the formula ( / g). The specific surface area mentioned above can be measured using, for example, a surface area measuring device manufactured by Micromeritics, trade name "Flow Sorb II 2300".

[0050] The average secondary particle size of the abrasive grains (typically 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 grinding rate, the aforementioned average secondary particle size is preferably 30 nm or more, more preferably 35 nm or more. In some embodiments, the aforementioned average secondary particle size may be, for example, 40 nm or more, 42 nm or more, and preferably 44 nm or more. Furthermore, the aforementioned average secondary particle size is generally advantageous to be below 250 nm, preferably below 200 nm, and more preferably below 150 nm. In some preferred embodiments, the aforementioned average secondary particle size is below 120 nm, more preferably below 100 nm, and even more preferably below 70 nm.

[0051] It should be noted that, 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 abrasive grains can be determined by, for example, dynamic light scattering using a product manufactured by Nikkiso Corporation, "NanotracUPA-UT151".

[0052] The shape (appearance) of the abrasive particles (typically silica particles) can be spherical or non-spherical. Specific examples of non-spherical particles include peanut-shaped (i.e., peanut shell-shaped), cocoon-shaped, konpeito-shaped, and rugby ball-shaped particles. Preferably, silica particles that are mostly peanut-shaped or cocoon-shaped are used.

[0053] The average aspect ratio (average aspect ratio) of the abrasive grains (typically silica particles) is generally 1.0 or higher, preferably 1.05 or higher, more preferably 1.1 or higher, and may also be 1.2 or higher, but there is no particular limitation. As the average aspect ratio increases, a higher grinding rate can be achieved. Furthermore, from the viewpoint of reducing scratches, the average aspect ratio of the abrasive grains (typically silica particles) is preferably 3.0 or lower, more preferably 2.0 or lower, even more preferably 1.5 or lower, and may also be 1.4 or lower.

[0054] The shape (outline) or average aspect ratio of abrasive grains (typically silica particles) can be determined, for example, by observation using an electron microscope. As a specific step in determining the average aspect ratio, for example using a scanning electron microscope (SEM), for a predetermined number (e.g., 200) of abrasive grains (abrasive material particles, typically silica particles) whose individual particle shapes can be identified, the smallest rectangle tangent to each particle image is drawn. Then, for each rectangle drawn for each particle image, the length of its longer side (the value of the major diameter) divided by the length of its shorter side (the value of the minor diameter) is calculated, and this value is defined as the major diameter / minor diameter ratio (ARR). The average aspect ratio can be obtained by taking the arithmetic mean of the aspect ratios of the predetermined number of particles.

[0055] <Any water-soluble polymer>

[0056] The grinding composition disclosed herein may contain any water-soluble polymer other than the cellulose derivative (A) as an optional component, without significantly hindering the effectiveness of the invention. The type of water-soluble polymer is not particularly limited; a water-soluble polymer having at least one functional group selected from cationic, anionic, and nonionic groups may be used. Any water-soluble polymer may be a polymer having hydroxyl, carboxyl, acyl, acyloxy, sulfonyl, amide, quaternary ammonium, heterocyclic, vinyl, or polyoxyalkylene structures.

[0057] Examples of any water-soluble polymer include cellulose derivatives with a Mw of 80,000 or higher; starch derivatives; polymers containing oxyalkylene units, such as copolymers of ethylene oxide (EO) and propylene oxide (PO); vinyl alcohol polymers; polymers containing N-vinyl monomer units, imine derivatives, polymers containing N-(meth)acryloyl monomer units, and other polymers containing nitrogen atoms; and polymers containing carboxylic acids (including anhydrides). Specific examples include pullulan, random copolymers or block copolymers of ethylene oxide (EO) and propylene oxide (PO), polyglycerol, polyvinyl alcohol (PVA), acetalized polyvinyl alcohol, butene glycol polyvinyl alcohol, carboxyl-modified polyvinyl alcohol, sulfonic acid-modified polyvinyl alcohol, polyvinyl alcohol-polyvinylpyrrolidone graft copolymers, polyvinyl alcohol-polyvinylpyrrolidone random copolymers, polyvinyl alcohol-polyethylene oxide graft copolymers, polyvinyl alcohol-polyethylene oxide random copolymers, polyisoprene sulfonic acid, and poly... Vinyl sulfonic acid, polyallyl sulfonic acid, polyisoprene sulfonic acid, polystyrene sulfonate, polyacrylate, polyvinyl acetate, polyethylene glycol, polyvinylimidazolium, polyvinylcarbazole, polyvinylpyrrolidone, polyvinylacetamide, polyacrylamide morpholine, polyhydroxyethylacrylamide, polyallylamine, glycidyl-modified polyallylamine, methyl diallylamine-sulfur dioxide copolymer, polyvinylcaprolactam, polyvinylpiperidine, olefin-maleic acid (anhydride) copolymer, styrene-maleic acid (anhydride) copolymer, etc. From the viewpoint that the composition for grinding can improve grinding performance, vinyl alcohol polymers and polymers containing N-(meth)acryloyl group monomer units are preferred as any water-soluble polymer. Any water-soluble polymer can be used alone or in combination of two or more. From the viewpoint of simplifying the composition, the grinding composition disclosed herein may also be free of any water-soluble polymer other than the cellulose derivative (A) described above.

[0058] The weight-average molecular weight (Mw) of any water-soluble polymer is not particularly limited. For example, the Mw of any water-soluble polymer can be approximately 200 × 10⁻⁶. 4 The following can also be approximately 150×10 4 From the perspective of cleanliness, the following is approximately 100×10. 4 The following can also be approximately 50×10 4 Below. Furthermore, from the viewpoint of protecting the polished surface, the Mw of any water-soluble polymer can, for example, be 0.5 × 10⁻⁶. 4 The above, or 0.7 × 10 4 That's all. In some implementations, the above Mw can be 1×10. 4 The above, or 2×10 4 The above, for example, 5×10 4The above applies. For any water-soluble polymer, Mw can be determined using the weight-average molecular weight (converted from aqueous or polyethylene glycol) obtained through GPC. The GPC determination conditions can be the same as those for the cellulose derivative (A) described above.

[0059] In a grinding composition containing any water-soluble polymer, the percentage of the water-soluble polymer in the total water-soluble polymer contained in the grinding composition is preferably set to about 50% by weight or less (e.g., less than 50% by weight), and may be 30% by weight or less, less than 10% by weight, less than 3% by weight, or less than 1% by weight. The technology disclosed herein can preferably be implemented such that the grinding composition is substantially free of any water-soluble polymer.

[0060] <surfactants>

[0061] The grinding compositions disclosed herein may contain surfactants or may not contain surfactants substantially. In some embodiments, the grinding compositions contain surfactants. By containing surfactants in the grinding compositions, the dispersibility of the water-soluble polymers in the grinding compositions is improved, thereby improving the flowability of the filter. In addition, depending on the composition containing surfactants, the quality of the grinding surface can be further improved (reducing fogging, reducing defects, etc.). As surfactants, any type of anionic, cationic, nonionic, or amphoteric surfactants can be used. Generally, anionic or nonionic surfactants can be appropriately used. From the viewpoints of reducing fogging and low foaming and ease of pH adjustment, nonionic surfactants are more preferred. Examples of nonionic surfactants include alkylene oxide polymers such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol; polyoxyalkylene oxide derivatives (e.g., polyoxyalkylene oxide adducts) such as polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene alkylamines, polyoxyalkylene alkyl glucosides, polyoxyethylene fatty acid esters, polyoxyethylene glycerol ether fatty acid esters, and polyoxyethylene sorbitan fatty acid esters; and copolymers of various alkylene oxides (e.g., diblock copolymers, triblock copolymers, random copolymers, and alternating copolymers). Surfactants can be used alone or in combination of two or more.

[0062] Specific examples of nonionic surfactants include block copolymers of ethylene oxide (EO) and propylene oxide (PO) (diblock copolymers, PEO-PPO-PEO triblock copolymers, PPO-PEO-PPO triblock copolymers, etc.), random copolymers of EO and PO, polyethylene 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 isodecanyl ether, polyoxyethylene tridecyl ether, polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene isostearyl ether, polyoxyethylene oil ether, polyoxyethylene phenyl ether, and polyoxyethylene... Octylphenyl ether, polyoxyethylene nonylphenyl ether, polyoxyethylene dodecylphenyl ether, polyoxyethylene styrene phenyl ether, polyoxyethylene laurylamine, polyoxyethylene stearylamine, polyoxyethylene oleylamine, polyoxyethylene methyl glucoside, polyoxypropylene methyl glucoside, polyoxyethylene monolaurate, polyoxyethylene monostearate, polyoxyethylene distearate, polyoxyethylene monooleate, polyoxyethylene dioleate, polyoxyethylene monolaurate dehydrated sorbitol, polyoxyethylene monopalmitate dehydrated sorbitol, polyoxyethylene monostearate dehydrated sorbitol, polyoxyethylene monooleate dehydrated sorbitol, polyoxyethylene monooleate dehydrated sorbitol, polyoxyethylene trioleate dehydrated sorbitol, polyoxyethylene sorbitol tetraoleate, polyoxyethylene castor oil, polyoxyethylene hydrogenated castor oil, ethylenediaminetetrapolyoxyethylene polyoxypropylene (poloxamine), etc. Among the preferred surfactants are block copolymers of EO and PO (especially triblock copolymers of the PEO-PPO-PEO type), random copolymers of EO and PO, and polyoxyethylene alkyl ethers (e.g., polyoxyethylene decyl ether). As a polyoxyethylene alkyl ether, a polyoxyethylene alkyl ether with an EO addition molar number of about 1 to 10 (e.g., about 3 to 8) is preferred.

[0063] The molecular weight of the surfactant is preferably less than 5000, and from the viewpoint of reducing aggregates of cellulose derivative (A) or of good filterability and detergency, it is preferably 4500 or less, for example, less than 4000. Furthermore, from the viewpoint of interfacial activity, a molecular weight of 200 or more is generally appropriate, and from the viewpoint of reducing haze, it is preferably 250 or more (e.g., 300 or more). A more preferred range of molecular weight for 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 less than 2000, more preferably 1900 or less (e.g., less than 1800), further preferably 1500 or less, and may also be 1000 or less (e.g., 500 or less). Additionally, when a block copolymer of EO and PO is used as the surfactant, its weight-average molecular weight may be 500 or more, 1000 or more, 1500 or more, 2000 or more, or 2500 or more. The upper limit of the above weight-average molecular weight is, for example, less than 5000, preferably less than 4500, for example, less than 4000, less than 3800, or less than 3500.

[0064] The molecular weight of the surfactant can be calculated from the chemical formula or obtained by GPC (conversion between aqueous and polyethylene glycol). The same conditions as those for the cellulose derivative (A) described above can be used for GPC determination. For example, in the case of polyoxyethylene alkyl ethers, the molecular weight calculated from the chemical formula is preferred; in the case of block copolymers of EO and PO, the weight-average molecular weight obtained by GPC is preferred.

[0065] The grinding composition disclosed herein can be implemented in a manner that is substantially free of surfactant or in a manner where the content of surfactant is limited. In the manner where the grinding composition is substantially free of surfactant or in a manner where the content of surfactant is limited, the content of surfactant in the grinding composition relative to 100 parts by weight of the aforementioned cellulose derivative (A) can be approximately less than 50 parts by weight, less than 30 parts by weight, less than 10 parts by weight, less than 3 parts by weight, less than 1.5 parts by weight, or less than 1 part by weight, but there is no particular limitation.

[0066] <Other Ingredients>

[0067] The polishing compositions disclosed herein may, as needed, contain known additives that can be used in polishing compositions (e.g., polishing compositions for fine polishing steps of silicon wafers), such as organic acids, organic acid salts, inorganic acids, inorganic acid salts, chelating agents, preservatives, fungicides, etc., without significantly impairing the effects of the invention.

[0068] Organic acids and their salts, as well as inorganic acids and their salts, can be used alone 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; organic phosphonic acids such as nitric acid tris(methylene phosphate) (NTMP) and phosphonobutyltricarboxylic acid (PBTC). Examples of organic acid salts include alkali metal salts (sodium, potassium, lithium, etc.) and ammonium salts of organic acids. Examples of inorganic acids include hydrochloric acid, phosphoric acid, sulfuric acid, phosphonic acid, nitric acid, hypophosphonic acid, boric acid, and carbonic acid. Examples of inorganic acid salts include alkali metal salts (sodium, potassium, lithium, etc.) and ammonium salts of inorganic acids.

[0069] The aforementioned chelating agents can be used alone or in combination of two or more. Examples of chelating agents include aminocarboxylic acid chelating agents and organophosphonic acid chelating agents. Suitable examples of chelating agents include ethylenediaminetetra(methylenephosphonic acid), diethylenetriaminepenta(methylenephosphonic acid), and diethylenetriaminepentaacetic acid. Examples of preservatives and fungicides include isothiazolinone compounds, parabens, phenoxyethanol, etc.

[0070] The polishing composition disclosed herein is preferably substantially free of oxidants. This is because if the polishing composition contains an oxidant, the surface of the substrate (e.g., a silicon wafer) will be oxidized and an oxide film will form when the polishing composition is supplied to it, which may sometimes reduce the polishing rate. Specific examples of oxidants mentioned herein include hydrogen peroxide (H2O2), sodium persulfate, ammonium persulfate, sodium dichloroisocyanurate, etc. It should be noted that "substantially free of oxidants" in polishing compositions means that they do not actively contain oxidants. Therefore, polishing compositions that unavoidably contain trace amounts of oxidants from raw materials, manufacturing processes, etc. (e.g., the molar concentration of the oxidant in the polishing composition is 0.001 mol / L or less, preferably 0.0005 mol / L or less, more preferably 0.0001 mol / L or less, further preferably 0.00005 mol / L or less, particularly preferably 0.00001 mol / L or less) are included in the concept of "substantially free of oxidants" in polishing compositions.

[0071] <ph>

[0072] The pH of the polishing composition disclosed herein is not particularly limited, and an appropriate pH can be adopted depending on the substrate, etc. In some embodiments, the pH of the polishing composition is preferably 8.0 or higher, more preferably 8.5 or higher, and more preferably 9.0 or higher. If the pH of the polishing composition is higher, there is a tendency for the polishing rate to increase. On the other hand, from the viewpoint of preventing the dissolution of silica particles and suppressing the reduction of mechanical polishing effect, the pH of the polishing composition is generally preferably 12.0 or lower, preferably 11.0 or lower, more preferably 10.8 or lower, and even more preferably 10.5 or lower.

[0073] It should be noted that, in the technology disclosed herein, the pH of the grinding composition can be obtained by using a pH meter and a standard buffer solution, after three-point calibration, by inserting a glass electrode into the composition to be measured, and measuring the stable value after at least 2 minutes. The pH meter can be, for example, a glass electrode type hydrogen ion concentration indicator (model F-72) manufactured by Horiba Corporation. The standard buffer solutions used are phthalate pH buffer (pH: 4.01, 25°C), neutral phosphate pH buffer (pH: 6.86, 25°C), and carbonate pH buffer (pH: 10.01, 25°C).

[0074] <Grinding Fluid>

[0075] The polishing composition disclosed herein is typically supplied to the surface of a substrate in the form of an polishing slurry containing the polishing composition for polishing the substrate. The polishing slurry may be, for example, a polishing slurry prepared by diluting any of the polishing compositions disclosed herein (typically by dilution with water). Alternatively, the polishing composition may be used directly as a polishing slurry. Other examples of polishing slurries containing the polishing composition disclosed herein include polishing slurries prepared by adjusting the pH of the composition.

[0076] The content of the aforementioned cellulose derivative (A) in the grinding fluid is not particularly limited and can be set to, for example, 0.0001% by weight or more. From the viewpoint of reducing haze, a preferred content is 0.0005% by weight or more, more preferably 0.001% by weight or more, and even more preferably 0.002% by weight or more, for example, 0.005% by weight or more. In addition, from the viewpoint of grinding rate, in some preferred embodiments, the aforementioned content can be set to 0.2% by weight or less, more preferably 0.1% by weight or less, even more preferably 0.05% by weight or less, even more preferably 0.02% by weight or less, even more preferably 0.015% by weight or less, particularly preferably 0.012% by weight or less, and may also be 0.010% by weight or less (for example, less than 0.010% by weight).

[0077] In a grinding composition containing abrasive particles, the content of the aforementioned cellulose derivative (A) in the grinding composition can be specified by its relative relationship with the abrasive particles (typically silica particles). The content of the aforementioned cellulose derivative (A) relative to 100 parts by weight of the abrasive particles can be set to, for example, 0.01 parts by weight or more, and setting it to 0.1 parts by weight or more is appropriate, but there is no particular limitation. In some preferred embodiments, from the viewpoint of better utilizing the effects of the aforementioned cellulose derivative (A) (reducing defects and reducing haze), the aforementioned content is 1 part by weight or more, preferably 3 parts by weight or more, more preferably 5 parts by weight or more, and can be 10 parts by weight or more, 15 parts by weight or more, or 20 parts by weight or more. Furthermore, the content of the aforementioned cellulose derivative (A) relative to 100 parts by weight of the abrasive particles is, in some embodiments, for example, 30 parts by weight or less, and 20 parts by weight or less is appropriate, preferably 15 parts by weight or less, more preferably 10 parts by weight or less (e.g., less than 10 parts by weight), and can be 9 parts by weight or less, or 8 parts by weight or less. By limiting the content of the aforementioned cellulose derivative (A), there is a tendency to increase the grinding rate.

[0078] The content of alkaline compounds in the polishing slurry is not particularly limited. From the viewpoint of increasing polishing rate, it is generally appropriate to set the above content to 0.00001% by weight or more, preferably 0.00005% by weight or more, more preferably 0.0001% by weight or more, particularly preferably 0.0003% by weight or more, and may be 0.0005% by weight or more, 0.001% by weight or more, or 0.005% by weight or more. Furthermore, from the viewpoint of improving surface quality (e.g., reducing haze), it is appropriate to set the above content to less than 0.1% by weight, preferably less than 0.05% by weight, more preferably less than 0.03% by weight (e.g., less than 0.025% by weight). In some preferred embodiments, the above content may be less than 0.01% by weight or less than 0.008% by weight.

[0079] In polishing slurries containing abrasive particles (typically silica particles), the content of these particles is not particularly limited, but is, for example, 0.001% by weight or more, preferably 0.05% by weight or more, and more preferably 0.10% by weight or more. Higher polishing rates can be achieved by increasing the abrasive particle content. A content of 10% by weight or less is suitable, preferably 7% by weight or less, more preferably 5% by weight or less, and even more preferably 2% by weight or less, for example, 1% by weight or less. In some methods, the content may be 0.75% by weight or less, 0.5% by weight or less (e.g., less than 0.5% by weight), 0.25% by weight or less (e.g., less than 0.25% by weight), or even 0.2% by weight or less. By limiting the abrasive particle content to the above ranges, surface quality maintenance is easily achieved.

[0080] In the case where the polishing slurry contains a surfactant, the content of the surfactant in the polishing slurry is not particularly limited. Generally, the content of the surfactant, for example, from the viewpoint of improving the dispersibility and detergency of the cellulose derivative (A), can be set to 0.00001% by weight or more. From the viewpoint of reducing haze, in some cases, the content can be 0.0002% by weight or more, 0.0003% by weight or more, or 0.0005% by weight or more. Furthermore, from the viewpoint of polishing rate, the content can be set to 0.1% by weight or less, 0.01% by weight or less, or 0.005% by weight or less (e.g., 0.002% by weight or less). Additionally, in cases where the polishing composition is substantially surfactant-free or where the content of the surfactant is limited, the content of the surfactant in the polishing slurry can be less than 0.001% by weight, less than 0.0001% by weight, or less than 0.00001% by weight.

[0081] <Concentrated Solution>

[0082] The polishing composition disclosed herein can be in a concentrated form (i.e., a concentrated polishing slurry) before being supplied to a substrate. Such a concentrated polishing composition is advantageous from the viewpoints of convenience in manufacturing, transportation, and storage, as well as cost reduction. The concentration ratio is not particularly limited; for example, it can be set to approximately 2 to 100 times by volume, and typically 5 to 50 times (e.g., 10 to 40 times) is appropriate. This concentrate can be diluted at a desired time to prepare a polishing slurry (working paste), which is then supplied to the substrate. The dilution can be performed, for example, by adding water to the concentrate and mixing.

[0083] When the grinding composition (i.e., concentrate) is diluted and used for grinding, the content of the cellulose derivative (A) in the concentrate can be set to, for example, 3% by weight or less. From the viewpoint of the filterability or washability of the grinding composition, the above content is generally preferably 1% by weight or less, more preferably 0.5% by weight or less, and may also be 0.3% by weight or less. In addition, from the viewpoint of convenience in manufacturing, transportation, storage, etc., or cost reduction, the above content is generally appropriate to be 0.001% by weight or more, preferably 0.005% by weight or more, and more preferably 0.01% by weight or more.

[0084] In some embodiments, the content of alkaline compounds in the concentrate may be set to less than 15% by weight, for example. From the viewpoint of storage stability, the content is generally preferably 0.7% by weight or less, more preferably 0.4% by weight or less, and may also be 0.1% by weight or less, or 0.05% by weight or less. Furthermore, from the viewpoint of convenience in manufacturing, transportation, and storage, or cost reduction, the content of alkaline compounds in the concentrate may be set to 0.001% by weight or more, preferably 0.005% by weight or more, more preferably 0.01% by weight or more, and may also be 0.02% by weight or more, or 0.05% by weight or more.

[0085] In the aforementioned concentrate containing abrasive particles (typically silica particles), the content of these abrasive particles in the concentrate can be set, for example, to 25% by weight or less. From the viewpoint of dispersion stability or filterability of the grinding composition, this content is generally preferably 20% by weight or less, more preferably 15% by weight or less. In some preferred embodiments, the content of abrasive particles can be set to 10% by weight or less, or 5% by weight or less (e.g., less than 5% by weight). Furthermore, from the viewpoint of convenience in manufacturing, transportation, and storage, or cost reduction, the content of abrasive particles in the concentrate can be set, for example, to 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.

[0086] In the above-described concentrate containing a surfactant, the surfactant content in the concentrate can be set, for example, to 0.25% by weight or less, preferably to 0.15% by weight or less, more preferably to 0.1% by weight or less, and may also be 0.05% by weight or less, or 0.025% by weight or less. Furthermore, the surfactant content in the concentrate can be set, for example, to 0.0001% by weight or more, preferably to 0.001% by weight or more, more preferably to 0.005% by weight or more, and even more preferably to 0.01% by weight or more. Additionally, in the case where the grinding composition is substantially surfactant-free or where the surfactant content is limited, the surfactant content in the concentrate may be less than 0.01% by weight, less than 0.005% by weight, or less than 0.001% by weight.

[0087] <Preparation of Grinding Compositions>

[0088] The grinding composition used in the technology disclosed herein can be a single-agent type or a multi-agent type, primarily a two-agent type. For example, it can be configured by mixing agent A, which contains at least the abrasive particles of the grinding composition, with agent B, which contains at least a portion of the remaining components, and mixing and diluting them at appropriate times as needed to prepare a grinding fluid. Agents A and B may be filtered one or two times or more, or may not be filtered.

[0089] The preparation method of the grinding composition is not particularly limited. For example, the components constituting the grinding composition can be mixed using known mixing devices such as a wing mixer, an ultrasonic disperser, or a homogenizer. The method of mixing these components is not particularly limited; for example, all components can be mixed at once, or they can be mixed in a suitably set order. In addition, after mixing, filtration can be performed one or two times or more, or filtration can be omitted.

[0090] In some methods, the abrasive composition is preferably used for abrasive grinding of the substrate after filtration through a filter. The structure of the filter is not particularly limited, but a filter containing, for example, a layer made of a porous membrane is preferred. Alternatively, a filter having a layer of filter fibers made of filter fibers can be used. Examples of filters with a filter fiber layer include woven fabric filters (filter screens). The shape of the filter medium is not particularly limited, and depth filters, surface filters, deep-pleated filters (where the depth filter is pleated), and pleated filters (where the surface filter is pleated) can be used. From the viewpoint of improving the filterability of the target liquid, pleated filters are preferred.

[0091] In some embodiments, a filter with an average pore size of 0.15 μm or less as measured by a pore analyzer is preferably used; however, there is no particular limitation. The filter of the grinding composition disclosed herein exhibits excellent fluid permeability, thus enabling efficient filtration even when using a filter with an average pore size below a specified value, as described above, and better removal of aggregates that could cause defects. In some preferred embodiments, the average pore size of the filter used may be 0.14 μm or less, more preferably 0.12 μm or less, further preferably 0.10 μm or less, particularly preferably 0.08 μm or less, and may also be 0.06 μm or less. From the viewpoint of fluid permeability, the lower limit of the aforementioned average pore size may, for example, be 0.01 μm or more, or 0.03 μm or more.

[0092] Here, the average pore size of the filter in this specification can be taken as the pore size D50 value corresponding to 50% of the cumulative pore size distribution in the fine pore size distribution measured by the semi-dry method according to ASTM E1294-89. For example, it can be measured using a pore analyzer (CFP-1200AXL) manufactured by PMI. The above measurement method can also be used in the embodiments described later.

[0093] The filtration conditions (e.g., filtration differential pressure, filtration velocity, filtration volume) can be appropriately set based on common technical knowledge in the field and taking into account target quality or production efficiency. The filtration method is not particularly limited; for example, in addition to natural filtration under normal pressure, known filtration methods such as vacuum filtration, pressure filtration, and centrifugal filtration can be appropriately employed. Furthermore, additional filtration processes can be performed before or after the aforementioned filter, depending on the purpose of removing coarse particles or achieving high-precision filtration, either pre- or in multiple stages.

[0094] <Application>

[0095] The polishing composition disclosed herein is applicable to polishing substrates of various materials and shapes. The substrate material can be, for example, metals or semi-metals or alloys such as silicon, aluminum, nickel, tungsten, copper, tantalum, titanium, and stainless steel; glassy materials such as quartz glass, aluminosilicate glass, and glassy carbon; ceramic materials such as alumina, silicon dioxide, 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 substrate can be composed of multiple of these materials. The shape of the substrate is not particularly limited. The polishing composition disclosed herein is applicable to polishing, for example, plate-shaped or polyhedral-shaped substrates with planar surfaces, or to polishing the edges of substrates (e.g., wafer edges).

[0096] The polishing composition disclosed herein is particularly suitable for polishing surfaces formed of silicon materials (typically, polishing silicon wafers). Specific examples of silicon materials include monocrystalline silicon, amorphous silicon, and polycrystalline silicon. The polishing composition disclosed herein is particularly suitable for polishing surfaces formed of monocrystalline silicon (e.g., polishing silicon wafers).

[0097] The polishing composition disclosed herein is suitable for use in polishing steps of substrates (e.g., silicon wafers). For the substrate, prior to the polishing step using the polishing composition disclosed herein, general treatments suitable for the substrate may be performed in steps upstream of the polishing step, such as grinding or etching.

[0098] The polishing compositions disclosed herein are effective for use in finishing steps of substrates (e.g., silicon wafers) or in polishing steps immediately preceding them, and are particularly preferred for use in fine polishing steps. Here, a fine polishing step refers to the final polishing step in the manufacturing process of the target object (i.e., no further polishing steps are performed after this step). The polishing compositions disclosed herein can also be used in polishing steps upstream of fine polishing (referring to pre-polishing steps between coarse polishing and final polishing steps, typically including at least one polishing step, and possibly two, three, etc. polishing steps), for example, in polishing steps performed immediately preceding fine polishing.

[0099] The polishing compositions disclosed herein are effective, for example, for polishing (typically fine polishing or immediately preceding polishing) of silicon wafers whose surface condition has been adjusted to a surface roughness of 0.01 nm to 100 nm via upstream steps. They are particularly preferred for fine polishing. The surface roughness Ra of the substrate can be measured using, for example, a laser scanning surface roughness meter "TMS-3000WRC" manufactured by Schmitt Measurement System Inc.

[0100] <Grinding>

[0101] The polishing composition disclosed herein can, for example, be used for polishing a substrate in a manner that includes the following operations. A suitable method for polishing a silicon wafer as a substrate using the polishing composition disclosed herein is described below.

[0102] That is, a grinding slurry containing any of the grinding compositions disclosed herein is prepared. The preparation of the grinding slurry may also include operations such as adjusting the concentration (e.g., dilution) and pH of the grinding composition. Alternatively, the grinding composition may be used directly as a grinding slurry.

[0103] Next, the polishing slurry is supplied to the substrate, and polishing is performed using conventional methods. For example, in the case of finishing polishing of a silicon wafer, typically, the silicon wafer that has undergone the polishing step is placed in a general polishing apparatus, and polishing slurry is supplied to the polishing target surface of the silicon wafer through the polishing pad of the polishing apparatus. Typically, the polishing slurry is continuously supplied while the polishing pad is pressed against the polishing target surface of the silicon wafer, causing the two to move relative to each other (e.g., rotate). After this polishing step, the polishing of the substrate is completed.

[0104] The abrasive pads used in the above abrasive steps are not particularly limited. For example, polyurethane foam, non-woven fabric, or suede abrasive pads can be used. Each abrasive pad may or may not contain abrasive particles. Generally, abrasive pads without abrasive particles are preferred.

[0105] <Rinse>

[0106] The substrate (e.g., a silicon wafer) polished using the polishing composition can be rinsed with a rinsing solution containing the same components as the polishing composition except that it does not contain abrasive particles. In other words, the technology disclosed herein may also include a step (rinsing step) of rinsing the substrate (e.g., a silicon wafer) with a rinsing solution containing the same components as the polishing composition except that it does not contain abrasive particles. The rinsing step reduces residues such as abrasive particles that could cause defects or fogging on the surface of the substrate (e.g., a silicon wafer). The rinsing step can be performed between polishing steps, or after the final polishing step and before the cleaning step described later. Typically, this rinsing solution can be a rinsing composition containing a cellulose derivative with a Mw of less than 80,000 (e.g., a composition for rinsing silicon wafers). By using a rinsing composition containing the aforementioned cellulose derivative with a Mw of less than 80,000, the substrate (e.g., a silicon wafer) polished using any of the polishing compositions disclosed herein can be properly rinsed. Furthermore, the rinsing composition described above may have the same composition as the polishing composition except that it does not contain abrasive particles, and therefore will not be repeated here.

[0107] <Wash clean>

[0108] Substrates polished using the polishing composition disclosed herein are typically cleaned. Cleaning can be performed using a suitable cleaning solution. The cleaning solution used is not particularly limited; for example, in the semiconductor industry, common cleaning solutions such as SC-1 (a mixture of ammonium hydroxide (NH4OH), hydrogen peroxide (H2O2), and water (H2O), SC-2 (a mixture of HCl, H2O2, and H2O), ozone water cleaning solution, and hydrofluoric acid cleaning solution can be used. The temperature of the cleaning solution can be set in a range from, for example, room temperature (typically about 15°C to 25°C) to about 90°C. From the viewpoint of improving cleaning effect, a cleaning solution with a temperature of about 50°C to 85°C is preferred.

[0109] As described above, the technology disclosed herein includes a method for manufacturing an abrasive (e.g., a method for manufacturing a silicon wafer) that includes a polishing step using any of the above-described polishing methods, and an abrasive (e.g., a silicon wafer) manufactured by the method.

[0110] The matters disclosed in this specification include the following.

[0111] [1] A grinding composition comprising a cellulose derivative and an alkaline compound,

[0112] The weight-average molecular weight of the aforementioned cellulose derivatives is less than 80,000.

[0113] [2] According to the grinding composition described in [1] above, wherein the weight-average molecular weight of the aforementioned cellulose derivative is 4,000 or more and less than 80,000.

[0114] [3] The grinding composition according to [1] or [2] above further contains abrasive particles.

[0115] [4] According to the grinding composition described in [3] above, wherein the aforementioned abrasive grains are colloidal silica with an average primary particle size of 20 nm or more and 50 nm or less.

[0116] [5] The polishing composition according to any one of [1] to [4] above is used for polishing a surface formed of silicon material.

[0117] [6] A concentrate of the grinding composition described in any one of [1] to [5] above.

[0118] [7] A polishing method comprising the step of polishing a surface formed of silicon material using the polishing composition described in any one of [1] to [5] above.

[0119] [8] A rinsing composition comprising a cellulose derivative having a weight-average molecular weight of less than 80,000.

[0120] Example

[0121] The following describes some embodiments related to the present invention; however, the invention is not intended to be limited to the content disclosed in these embodiments. Furthermore, in the following description, unless otherwise specified, "parts" and "%" refer to weight.

[0122] Experiment 1

[0123] <Preparation of Concentrated Solution of Grinding Composition>

[0124] (Examples 1-2 and Comparative Example 1)

[0125] A concentrated solution of each example grinding composition was prepared by mixing abrasive particles, hydroxyethyl cellulose (HEC), ammonia, and deionized water. Colloidal silica with an average primary particle size of 35 nm was used as the abrasive particles. HEC with the Mw values ​​disclosed in Table 1 was used as the HEC.

[0126] <Filtration Processing>

[0127] The concentrate of the grinding composition associated with each example was filtered according to the following filtration conditions.

[0128] [Filtering conditions]

[0129] Suction Pump: Oil-free pump PSH028AA

[0130] Filter clamp: KP-47H 47mm polysulfone clamp

[0131] Pressure Relief Container: VT-500

[0132] Filtration pressure differential: 80 kPa

[0133] Filter: Average pore size: 0.145 μm, filter diameter: 47 mm

[0134] <Preparation of Grinding Compositions>

[0135] By diluting the concentrated solution of the grinding composition after filtration with deionized water to a volume ratio of 20, and adjusting the concentration of abrasive particles to 0.5%, the concentration of HEC to 0.1%, and the concentration of ammonia to 0.01%, the grinding compositions related to each example were obtained.

[0136] Evaluation of the surface quality of the ground surface

[0137] (Grinding of silicon wafers)

[0138] As a substrate, a commercially available single-crystal silicon wafer with a diameter of 300 mm (conductivity: P-type, crystal orientation: ...) that has undergone grinding and etching is prepared. <100> Silicon wafers without COP (Crystal Originated Particles) were pre-polished under the following polishing conditions 1. Pre-polishing was performed using a polishing slurry in deionized water containing 0.6% abrasive particles (colloidal silica with an average primary particle size of 35 nm) and 0.08% tetramethylammonium hydroxide (TMAH).

[0139] [Grinding Condition 1]

[0140] Grinding device: Single-blade grinding device model "PNX-332B" manufactured by Okamoto Machinery Manufacturing Co., Ltd.

[0141] Grinding load: 20 kPa

[0142] Platform speed: 20 rpm

[0143] Grinding head (carrier) rotation speed: 20 rpm

[0144] Abrasive pad: Manufactured by NITTA DuPont, product name "SUBA400"

[0145] The slurry supply rate is 1.0 L / min.

[0146] The temperature of the grinding slurry: 20℃

[0147] Platform cooling water temperature: 20℃

[0148] Grinding time: 2 minutes

[0149] Using the polishing composition associated with each example as the polishing fluid, the pre-polished silicon wafer was polished under polishing condition 2, and then polished under polishing condition 3.

[0150] [Grinding Condition 2]

[0151] Grinding device: Single-blade grinding device model "PNX-332B" manufactured by Okamoto Machinery Manufacturing Co., Ltd.

[0152] Grinding load: 16 kPa

[0153] Platform speed: 52 rpm

[0154] Grinding head (carrier) rotation speed: 50 rpm

[0155] Abrasive pad: Product name "POLYPAS275NX" manufactured by FUJIBO Ehime Co., Ltd.

[0156] The slurry supply rate is 1.5 L / min.

[0157] The temperature of the polishing slurry: 20℃

[0158] Platform cooling water temperature: 20℃

[0159] Grinding time: 2 minutes

[0160] [Grinding Condition 3]

[0161] Grinding device: Single-blade grinding device model "PNX-332B" manufactured by Okamoto Machinery Manufacturing Co., Ltd.

[0162] Grinding load: 20 kPa

[0163] Platform speed: 52 rpm

[0164] Grinding head (carrier) rotation speed: 50 rpm

[0165] Abrasive pad: Product name "POLYPAS275NX" manufactured by FUJIBO Ehime Co., Ltd.

[0166] The slurry supply rate is 1.5 L / min.

[0167] The temperature of the polishing slurry: 20℃

[0168] Platform cooling water temperature: 20℃

[0169] Grinding time: 2 minutes

[0170] A first cleaning tank containing a cleaning solution maintained at 70°C with a volume ratio of NH4OH (29%):H2O2 (31%):deionized water = 2:5.3:48 was prepared, along with a second cleaning tank containing ultrapure water at 25°C. The ground silicon wafer was immersed in the first cleaning tank for 6 minutes, then in the second cleaning tank for 40 minutes, and then immersed again in the first cleaning tank for 6 minutes and the second cleaning tank for 4 minutes before being dried.

[0171] <Defect Measurement>

[0172] After cleaning, the number of defects (the sum of LPD and LPD-N) on the silicon wafer surface was measured using a wafer inspection device manufactured by KLA-Tencor, trade name "Surfscan SP5", in DC mode. The results were converted into relative values ​​with the number of defects in Comparative Example 1 as 100%, and the values ​​were recorded in the column of Table 1.

[0173] <Haze Measurement>

[0174] After cleaning, the haze (ppm) of the silicon wafer surface was measured using a wafer inspection device manufactured by KLA-Tencor, trade name "Surfscan SP5", in DW2O mode. The results were converted to relative values ​​with the haze value of Comparative Example 1 as 100%, and the values ​​are recorded in the column of Table 1.

[0175] Experiment 2

[0176] <Preparation of Concentrated Solution of Grinding Composition>

[0177] (Examples 3-7 and Comparative Examples 2-4)

[0178] Abrasive particles, HEC having the Mw disclosed in Table 2, ammonia, and deionized water were mixed to prepare concentrated solutions of the grinding compositions associated with each example. Comparative Example 2 further mixed polyoxyethylene decyl ether (C10PEO5) as a surfactant to prepare a concentrated solution of the grinding composition.

[0179] <Filtration Processing>

[0180] In addition to using a filter with the average pore size shown in Table 2, the concentrate of the grinding composition related to each example was filtered according to the filtration conditions of Experiment 1.

[0181] <Preparation of Grinding Compositions>

[0182] By diluting the concentrated solution of the grinding composition after filtration with deionized water to a volume ratio of 40 times, and adjusting the concentration of abrasive particles to 0.12%, the concentration of HEC to 0.009%, and the concentration of ammonia to 0.005%, the grinding compositions related to each example were obtained. The concentration of surfactant in the grinding composition related to Comparative Example 2 was set to 0.0004%.

[0183] Evaluation of the surface quality of the ground surface

[0184] (Grinding of silicon wafers)

[0185] As a substrate, a commercially available single-crystal silicon wafer with a diameter of 300 mm (conductivity: P-type, crystal orientation: ) that has undergone grinding and etching is prepared. <100> The silicon wafers, which were pre-polished under the following polishing conditions (1) without COP (Crystal Originated Particles), were free of COP. Pre-polishing was performed using a polishing slurry in deionized water containing 1.0% abrasive particles (colloidal silica with an average primary particle size of 35 nm) and 0.068% potassium hydroxide.

[0186] [Grinding Condition 1]

[0187] Grinding device: Single-blade grinding device model "PNX-332B" manufactured by Okamoto Machinery Manufacturing Co., Ltd.

[0188] Grinding load: 12 kPa

[0189] Platform speed: 52 rpm

[0190] Grinding head (carrier) rotation speed: 50 rpm

[0191] Abrasive pad: Product name "POLYPAS275NX" manufactured by FUJIBO Ehime Co., Ltd.

[0192] The slurry supply rate is 1.0 L / min.

[0193] The temperature of the polishing slurry: 20℃

[0194] Platform cooling water temperature: 20℃

[0195] Grinding time: 4 minutes

[0196] Using the polishing composition associated with each example as the polishing fluid, the pre-polished silicon wafer was polished under polishing condition 2, and then polished under polishing condition 3.

[0197] [Grinding conditions 2 and 3]

[0198] Grinding device: Single-blade grinding device model "PNX-332B" manufactured by Okamoto Machinery Manufacturing Co., Ltd.

[0199] Grinding load: 12 kPa

[0200] Platform speed: 52 rpm

[0201] Grinding head (carrier) rotation speed: 50 rpm

[0202] Abrasive pad: Product name "POLYPAS275NX" manufactured by FUJIBO Ehime Co., Ltd.

[0203] The slurry supply rate is 2.0 L / min.

[0204] The temperature of the polishing slurry: 20℃

[0205] Platform cooling water temperature: 20℃

[0206] Grinding time: 4 minutes

[0207] The polished silicon wafer is removed from the polishing device and cleaned with ozone water cleaning solution (60 seconds). Next, it is cleaned with SC-1 cleaning solution and a brush (110 seconds). Then, a cleaning cycle is performed, consisting of two sets: one using ozone water cleaning solution (20 seconds) and the other using hydrofluoric acid cleaning solution (15 seconds). This cycle is repeated for a total of 3 sets. Finally, the wafer is cleaned with ozone water cleaning solution (20 seconds). The silicon wafer is then dried.

[0208] <Defect and Haze Measurement>

[0209] Defects and haze were measured using the method described in Experiment 1. The results were converted into relative values ​​with the number of defects and haze value of Comparative Example 3 as 100%, and the values ​​were recorded in the corresponding column of Table 2. A haze value below 110 was considered to be able to maintain a low haze value.

[0210] <Evaluation of Fluid Permeability (Common to Experiments 1 and 2)>

[0211] The concentrate of the grinding composition associated with each example was diluted with deionized water to an HEC concentration of 1.3% to obtain the evaluation sample. Deionized water was also prepared as a reference. Containers containing the evaluation sample and the reference (deionized water) were stored in an air bath at 25°C. The filter used for flowability evaluation was rinsed with approximately 10 mL of deionized water. Next, following the filtration conditions of Experiment 1 above, the flow time was measured in the order of 50 g of reference and 50 g of evaluation sample. The ratio of the flow time of the evaluation sample to the flow time of the reference (flow time ratio) was calculated as the flow rate index. This procedure was performed for each example to obtain the flow rate index for each example. The obtained results (flow rate index) were converted to a relative value with the flow rate index of Comparative Example 2 as 100%, and the obtained values ​​were recorded in the corresponding column of Tables 1 and 2. Cases where flow was not completed within the specified time were recorded as "no flow".

[0212] [Table 1]

[0213]

[0214] [Table 2]

[0215]

[0216] As shown in Table 1, in Experiment 1, the grinding compositions of Examples 1-2, which contained HEC with a Mw of less than 80,000, reduced the haze value compared to Comparative Example 1, which used HEC with a Mw of 80,000 or more, and reduced defects by more than 22% on a relative basis. Example 1, which used HEC with a Mw of 20,000, achieved an even better defect reduction effect. Furthermore, the filters of the grinding compositions of Examples 1-2 also exhibited good flowability. In Experiment 2, as shown in Table 2, similar to Experiment 1, the grinding compositions of Examples 3-7, which used HEC with a Mw of less than 80,000, were confirmed to have a better defect reduction effect compared to Comparative Examples 3 and 4, which used HEC with Mw of 90,000 and Mw of 280,000, respectively. A comparison of Comparative Examples 2 and 3 shows that while combining HEC with a Mw of 280,000 with a surfactant improved the flowability of the filter and significantly reduced the number of defects, the defect reduction effect was still not as good as that of Examples 3-7. Furthermore, it was confirmed that the results of Examples 3-6, which evaluated the grinding composition containing 0.7 million Mw HEC by filtering filters with different pore sizes, showed that the grinding composition containing low molecular weight HEC also exhibited excellent fluid permeability even for filters with small average pore sizes, which can further reduce defects.

[0217] Specific examples of the present invention have been described in detail above; however, these are merely illustrative and do not limit the scope of the claims. The technology described in the claims includes technologies modified or altered from the specific examples described above.< / ph>

Claims

1. A grinding composition comprising a cellulose derivative and an alkaline compound, The weight-average molecular weight of the cellulose derivative is less than 80,000.

2. The grinding composition according to claim 1, wherein, The weight-average molecular weight of the cellulose derivative is above 4,000 and less than 80,000.

3. The grinding composition according to claim 1 or 2, further comprising abrasive grains.

4. The grinding composition according to claim 3, wherein, The abrasive particles are colloidal silicon dioxide with an average primary particle size of 20 nm or more and 50 nm or less.

5. The polishing composition according to claim 1 or 2, used for polishing surfaces formed of silicon material.

6. A concentrate of the grinding composition according to claim 1 or 2.

7. A polishing method comprising polishing a surface formed of silicon material using the polishing composition of claim 1 or 2.

8. A rinsing composition comprising a cellulose derivative having a weight-average molecular weight of less than 80,000.

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