Polishing composition, polishing method and method for producing semiconductor substrate

Abstract

A grinding composition is provided that can grind a layer containing 40% or more of Group 13 elements at a high grinding speed. The grinding composition is provided for grinding an object having a layer containing 40% or more of Group 13 elements, and comprises cationic modified silicon oxide, polyalkylene glycol, and an acid.

Description

[Technical Field]

[0001] This invention relates to a polishing composition, a polishing method, and a method for manufacturing a semiconductor substrate. [Previous Technology]

[0002] In recent years, with the increasing use of multilayer wiring on the surface of semiconductor substrates, chemical mechanical polishing (CMP) technology, which involves grinding and planarizing semiconductor substrates during device manufacturing, has been adopted. CMP is a method of planarizing the surface of a workpiece such as a semiconductor substrate using a polishing composition (slurry) containing abrasive particles such as silicon oxide, aluminum oxide, and cerium oxide, as well as a photoresist and a surfactant. The workpiece can be wiring, plugs, etc., formed from silicon, polycrystalline silicon, silicon oxide films, silicon nitride, metals, etc.

[0003] For example, as a technique for polishing a polycrystalline silicon film disposed on a silicon substrate having a separation region, Japanese Patent Application Publication No. 2007-103515 (corresponding to U.S. Patent Application Publication No. 2007 / 0077764) discloses a polishing method that includes a pre-polishing step using a pre-polishing composition containing abrasive particles, alkali, a water-soluble polymer and water, and a final polishing step using a final polishing composition containing abrasive particles, alkali, a water-soluble polymer and water. [Summary of the Invention]

[0004] [The problem the invention aims to solve]

[0005] In recent years, as semiconductor substrates, substrates with layers containing 40% or more of Group 13 elements have been used, and new requirements have been put forward for such substrates, such as polishing. These requirements have rarely been discussed in the past.

[0006] Therefore, the object of the present invention is to provide a grinding composition capable of grinding layers containing 40% by mass or more of Group 13 elements at a high grinding speed.

[0007] Furthermore, another object of the present invention is to provide a grinding composition in which the grinding speed of a layer containing 40% by mass or more of a Group 13 element is higher than that of other materials (i.e., higher selectivity). [Means for solving the problem]

[0008] In order to solve the aforementioned new problems, the inventors of this invention conducted in-depth research. As a result, it was discovered that the aforementioned problems could be solved by a grinding composition comprising cationic modified silicon oxide, polyolefin glycol and acid, and the present invention was thus completed.

[0009] That is, the present invention is a grinding composition for grinding an object having a layer having a content of more than 40% by mass of a group 13 element, and it comprises cationic modified silicon oxide, polyolefin diol and acid.

Implementation Method

[0011] [Form for implementing the invention]

[0012] This invention is a grinding composition for grinding objects having a layer containing more than 40% by mass of a Group 13 element, and comprises cationic modified silica, polyolefin glycol, and an acid. An embodiment of the grinding composition of this invention, having this configuration, is capable of grinding layers containing 40% or more of a Group 13 element at a high grinding speed. Furthermore, another embodiment of the grinding composition of this invention exhibits a higher grinding speed (i.e., higher selectivity) compared to the grinding speed of layers containing 40% or more of a Group 13 element than other materials.

[0013] Embodiments of the present invention will be described below. However, the present invention is not limited to the following embodiments. Throughout this specification, unless otherwise stated, the singular form should also be understood to include the concept of its plural form. Therefore, unless otherwise stated, articles for the singular form (e.g., "a," "an," "the," etc. in English) should be understood to include the concept of their plural forms. Furthermore, unless otherwise stated, the terminology used in this specification should be understood to be used in the sense commonly used in the art to which this invention pertains. Therefore, unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In case of any conflict, this specification (including definitions) shall prevail.

[0014] Unless otherwise specified, the operation and physical properties are measured at room temperature (above 20°C and below 25°C) and relative humidity (above 40%RH and below 50%RH).

[0015] [Abrasive Object] The abrasive object of the present invention has a layer containing 40% by mass or more of a Group 13 element (hereinafter also simply referred to as a Group 13 element layer). Specific examples of Group 13 elements include boron (B), aluminum (Al), gallium (Ga), and indium (In). A Group 13 element may be used alone or in combination of two or more.

[0016] The Group 13 element layer may include elements other than those in Group 13. Specific examples of other elements include silicon (Si), hydrogen (H), nitrogen (N), oxygen (O), carbon (C), phosphorus (P), and germanium (Ge). These other elements may be included individually or in combination of two or more.

[0017] The lower limit of the content of Group 13 elements contained in the Group 13 element layer is 40% by mass or more, preferably 45% by mass or more, more preferably 47% by mass or more, and even more preferably 50% by mass or more, relative to the total mass of the layer. Furthermore, the upper limit of the content of Group 13 elements contained in the Group 13 element layer is 100% by mass or less, preferably 95% by mass or less, and even more preferably 90% by mass or less, relative to the total mass of the layer.

[0018] The grinding object of the present invention may further include other materials in addition to the Group 13 element layer. Specific examples of other materials include silicon nitride, silicon carbonitride (SiCN), silicon oxide, polycrystalline silicon, amorphous silicon, polycrystalline silicon doped with n-type impurities, amorphous silicon doped with n-type impurities, titanium nitride, metallic elements, silicon germanium (SiGe), etc.

[0019] Specific examples of grinding objects containing silicon oxide include TEOS (Tetraethyl Orthosilicate) type silicon oxide surfaces (hereinafter also referred to as "TEOS" or "TEOS film") with tetraethyl orthosilicate as a precursor, high-density plasma films, undoped silicate glass (USG) films, phosphorus silicate glass (PSG) films, boron-phosphosilicone glass (BPSG) films, and rapid thermal oxidation (RTO) films.

[0020] Specific examples of metallic elements can be listed, such as tungsten, copper, cobalt, hafnium, nickel, gold, silver, platinum, palladium, rhodium, ruthenium, iridium, osmium, etc.

[0021] Furthermore, the grinding material of the present invention may also contain materials in which the content of Group 13 elements is greater than 0% by mass and less than 40% by mass. Specific examples of such materials include polycrystalline silicon doped with p-type impurities and amorphous silicon doped with p-type impurities.

[0022] [Catonic-Modified Silicon Oxide] The grinding composition of the present invention comprises cationic-modified silicon oxide (silicon dioxide having cationic groups) as abrasive particles. Cationic-modified silicon oxide can be used alone or in combination of two or more. Furthermore, commercially available or synthetic cationic-modified silicon oxide can be used.

[0023] As a cationic modified silicon oxide, cationic modified colloidal silicon oxide (colloidal silicon oxide with cationic groups) is preferred.

[0024] Examples of methods for manufacturing colloidal silicon oxide include the sodium silicate method and the sol-gel method. Colloidal silicon oxide manufactured by any of these methods is suitable for use as the abrasive grains of the present invention. However, from the viewpoint of reducing metal impurities, colloidal silicon oxide manufactured by the sol-gel method is preferred. Colloidal silicon oxide manufactured by the sol-gel method has a lower content of corrosive ions such as metal impurities and chloride ions that are diffusible in semiconductors, and is therefore preferred. Colloidal silicon oxide can be manufactured by conventionally known methods. Specifically, a hydrolysis-condensation reaction can be carried out using a hydrolyzable silicon compound (e.g., alkoxysilane or its derivative) as a raw material, thereby obtaining colloidal silicon oxide.

[0025] Here, cationic modification refers to the state in which cationic groups (e.g., amino groups or quaternary ammonium groups) are bonded to the surface of silicon oxide (preferably colloidal silicon oxide). Therefore, according to a preferred embodiment of the present invention, the cationic modified silicon oxide particles are amino-modified silicon oxide particles, more preferably amino-modified colloidal silicon oxide particles. According to this embodiment, the above-mentioned effects can be further enhanced.

[0026] To cationically modify silica (colloidal silica), a silane coupling agent having cationic groups (e.g., amino or quaternary ammonium groups) can be added to the silica (colloidal silica) and allowed to react at a predetermined temperature for a predetermined time. In a preferred embodiment of the invention, cationically modified silica is formed by fixing an amino-based silane coupling agent or a quaternary ammonium-based silane coupling agent onto the surface of silica (more preferably colloidal silica).

[0027] At this time, examples of silane coupling agents used include, for example, those described in Japanese Patent Application Publication No. 2005-162533. Specifically, examples include N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltriethoxysilane, γ-aminopropyltriethoxysilane ((3-aminopropyl)triethoxysilane), γ-aminopropyltrimethoxysilane, and γ-triethoxysilane. Silane coupling agents such as N-(α,γ-dimethyl-butylene)propylamine, N-phenyl-γ-aminopropyltrimethoxysilane, N-(vinylbenzyl)-β-aminoethyl-γ-aminopropyltriethoxysilane hydrochloride, octadecyldimethyl-(γ-trimethoxysilylpropyl))-ammonium chloride, and N-trimethoxysilylpropyl-N,N,N-trimethylammonium chloride are preferred from the viewpoint of good reactivity with colloidal silica. Furthermore, in this invention, a single silane coupling agent can be used, or two or more can be used in combination.

[0028] The silane coupling agent can be added directly to silica (colloidal silica), or it can be added to silica (colloidal silica) after dilution with a hydrophilic organic solvent or pure water. The formation of aggregates can be inhibited by dilution with a hydrophilic organic solvent or pure water. When diluting the silane coupling agent with a hydrophilic organic solvent or pure water, the silane coupling agent can be diluted to a concentration preferably of about 0.01 g to 1 g in 1 L of hydrophilic organic solvent or pure water; more preferably, a concentration of about 0.1 g to 0.7 g. There are no particular limitations on the hydrophilic organic solvent; examples include lower alcohols such as methanol, ethanol, isopropanol, and butanol.

[0029] Furthermore, by adjusting the amount of silane coupling agent added, the amount of cationic groups introduced onto the surface of silicon oxide (colloidal silicon oxide) can be adjusted. There is no particular limitation on the amount of silane coupling agent used, but it is preferably 0.1 mM (mmol / L) or more and 5 mM or less relative to the reaction solution; more preferably 0.5 mM or more and 3 mM or less.

[0030] There is no particular limitation on the processing temperature when using a silane coupling agent to cationicly modify silicon oxide (colloidal silicon oxide). It can be a temperature from room temperature (e.g., 25°C) to about the boiling point of the dispersion medium in which the silicon oxide (colloidal silicon oxide) is dispersed. Specifically, the temperature is above 0°C and below 100°C, and preferably above room temperature (e.g., 25°C) and below 90°C.

[0031] The shape of the cationic modified silicon oxide is not particularly limited. It can be spherical (hereinafter also referred to as spherical) or non-spherical. Specific examples of non-spherical shapes include polygonal prisms such as triangular prisms and quadrangular prisms, cylindrical shapes, straw-bag shapes with the center of the cylinder protruding from the end, donut shapes with the center of the disc penetrating through, plate-like shapes, so-called cocoon shapes with a constricted center, so-called associated spheres with multiple particles integrated, so-called konpeito shapes with multiple protrusions on the surface, rugby ball shapes, etc. There is no particular limitation.

[0032] The average primary particle size of the cationic modified silicon oxide is preferably 1 nm or larger, more preferably 3 nm or larger, and even more preferably 5 nm or larger. As the average primary particle size of the cationic modified silicon oxide increases, the grinding speed of the Group 13 element layer is further improved. Furthermore, the average primary particle size of the cationic modified silicon oxide is preferably 100 nm or smaller, more preferably 50 nm or smaller, and even more preferably 30 nm or smaller. As the average primary particle size of the cationic modified silicon oxide decreases, the grinding speed of the Group 13 element layer becomes higher than that of other materials (the selectivity becomes higher).

[0033] That is, the average primary particle size of the cationic modified silicon oxide is preferably 1 nm or more and 100 nm or less; more preferably 3 nm or more and 50 nm or less; and even more preferably 5 nm or more and 30 nm or less. Furthermore, the average primary particle size of the cationic modified silicon oxide can be calculated, for example, based on the specific surface area (SA) and density of the cationic modified silicon oxide calculated by the BET method. More specifically, the average primary particle size of the cationic modified silicon oxide is a value measured using the method described in the examples.

[0034] Furthermore, the average secondary particle size of the cationic modified silicon oxide is preferably 15 nm or more, more preferably 20 nm or more, and even more preferably 25 nm or more. As the average secondary particle size of the cationic modified silicon oxide increases, the resistance during grinding decreases, allowing for stable grinding. Furthermore, the average secondary particle size of the cationic modified silicon oxide is preferably 200 nm or less, more preferably 150 nm or less, and even more preferably 100 nm or less. As the average secondary particle size of the cationic modified silicon oxide decreases, the surface area per unit mass of cationic modified silicon oxide increases, increasing the contact frequency with the object being ground and further improving the contact speed. That is, the average secondary particle size of the cationic modified silicon oxide is preferably 15 nm or more and 200 nm or less; more preferably 20 nm or more and 150 nm or less; and even more preferably 25 nm or more and 100 nm or less. Furthermore, the average secondary particle size of the cationic modified silicon oxide was measured using the method described in the examples.

[0035] The ratio of the average secondary particle size to the average primary particle size of the cationic modified silicon oxide (average secondary particle size / average primary particle size, hereinafter also referred to as "average degree of association") is preferably greater than 1.0, more preferably greater than 1.1, and even more preferably greater than 1.2. As the average degree of association of the cationic modified silicon oxide increases, the grinding speed of the Group 13 element layer is further improved. Furthermore, the average degree of association of the cationic modified silicon oxide is preferably 4 or less, more preferably 3.5 or less, and even more preferably 3 or less. As the average degree of association of the cationic modified silicon oxide decreases, the grinding speed of the Group 13 element layer becomes higher than that of other materials (the selectivity becomes higher). That is, the average degree of association of the cationic modified silicon oxide is preferably greater than 1.0 and less than 4; more preferably greater than 1.1 and less than 3.5; and even more preferably greater than 1.2 and less than 3.

[0036] The average degree of association of cationic modified silicon oxide can be obtained by dividing the average secondary particle size of cationic modified silicon oxide by the average primary particle size.

[0037] The upper limit of the aspect ratio of the cationic modified silicon oxide in the polishing composition is not particularly limited, but it is preferably less than 2.0, more preferably 1.8 or less, and even more preferably 1.5 or less. Such a range can further reduce defects on the surface of the object being polished. Furthermore, the aspect ratio is the average value obtained by dividing the length of the longest side of the smallest rectangle circumscribed in the image of the colloidal silicon oxide particles by the length of the shortest side of the same rectangle, which can be obtained from an image of the colloidal silicon oxide particles obtained by scanning electron microscopy using general image analysis software. The lower limit of the aspect ratio of the cationic modified silicon oxide in the polishing composition is not particularly limited, but it is preferably 1.0 or more.

[0038] In the particle size distribution of cationic modified silicon oxide obtained by laser diffraction scattering, the lower limit of the ratio D90 / D50, which is the diameter of the particle when the cumulative particle weight from the microparticle side reaches 90% of the total particle weight and the diameter of the particle when the cumulative particle weight from the microparticle side reaches 50% of the total particle weight, is not particularly limited, but is preferably 1.1 or higher, more preferably 1.2 or higher, and even more preferably 1.3 or higher. Furthermore, in the particle size distribution of cationic modified silicon oxide obtained by laser diffraction scattering, the upper limit of the ratio D90 / D50, which is the diameter of the particle when the cumulative particle weight from the microparticle side reaches 90% of the total particle weight and the diameter of the particle when the cumulative particle weight from the microparticle side reaches 50% of the total particle weight, is not particularly limited, but is preferably 2.0 or lower, more preferably 1.7 or lower, and even more preferably 1.5 or lower. If it is within such a range, defects on the surface of the object being ground can be further reduced.

[0039] The size of cationic modified silicon oxide (average primary particle size, average secondary particle size, aspect ratio, D90 / D50, etc.) can be appropriately controlled by selecting the manufacturing method of cationic modified silicon oxide.

[0040] The lower limit of the zeta potential of the cationic modified silicon oxide in the grinding composition is preferably 4 mV or more, more preferably 4.5 mV or more, and even more preferably 5 mV or more. Furthermore, the upper limit of the zeta potential of the cationic modified silicon oxide in the grinding composition is preferably 70 mV or less, more preferably 65 mV or less, and even more preferably 60 mV or less. That is, the zeta potential of the abrasive particles in the grinding composition is preferably 4 mV or more and 70 mV or less; more preferably 4.5 mV or more and 65 mV or less; and even more preferably 5 mV or more and 60 mV or less.

[0041] If the cation-modified silicon oxide has the interfacial potential described above, the Group 13 element layer can be ground at a higher grinding speed. Furthermore, the grinding speed of the Group 13 element layer becomes higher than that of other materials (the selectivity becomes higher).

[0042] In this specification, the interfacial potential of the cationic modified silicon oxide is a value measured by the method described in the examples. The interfacial potential of the cationic modified silicon oxide can be adjusted by adjusting the amount of cationic groups contained in the cationic modified silicon oxide, the pH of the grinding composition, etc.

[0043] The content (concentration) of cationic modified silicon oxide in the grinding composition is not particularly limited, but is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, more preferably 0.5% by mass or more, and especially preferably greater than 0.5% by mass relative to the total mass of the grinding composition. Furthermore, the upper limit of the content of cationic modified silicon oxide in the grinding composition is preferably 10% by mass or less, more preferably 5% by mass or less, more preferably 4% by mass or less, and especially preferably less than 4% by mass relative to the total mass of the grinding composition. That is, the content of cationic modified silicon oxide relative to the total mass of the grinding composition is preferably 0.1% by mass or more and 10% by mass or less; more preferably 0.2% by mass or more and 5% by mass or less; more preferably 0.5% by mass or more and 4% by mass or less; and especially preferably greater than 0.5% by mass or less than 4% by mass.

[0044] If the content of cationic modified silicon oxide is within such a range, the Group 13 element layer can be ground at a higher grinding speed. Furthermore, the grinding speed of the Group 13 element layer becomes higher than that of other materials (the selectivity becomes higher). When the grinding composition contains two or more types of cationic modified silicon oxide, the content of cationic modified silicon oxide refers to its total amount.

[0045] Without impairing the effects of the present invention, the abrasive composition of the present invention may further comprise abrasive particles other than cationic modified silicon oxide. Such abrasive particles may be any of inorganic particles, organic particles, and organic-inorganic composite particles. Specific examples of inorganic particles include, for example, particles formed from metal oxides such as unmodified silicon oxide, aluminum oxide, cerium oxide, and titanium oxide, as well as silicon nitride particles, silicon carbide particles, and boron nitride particles. Specific examples of organic particles include, for example, polymethyl methacrylate (PMMA) particles. The aforementioned abrasive particles may be used alone or in combination of two or more. Furthermore, commercially available or synthetic abrasive particles may be used.

[0046] [Polyolefin-based glycol] The grinding composition of the present invention comprises a polyolefin-based glycol. The polyolefin-based glycol has the effect of promoting the grinding of the Group 13 element layer (increasing the grinding speed). The polyolefin-based glycol can be used alone or in combination of two or more. Furthermore, the polyolefin-based glycol can be a commercially available product or a synthetic product.

[0047] The types of polyolefin-based glycols are not particularly limited, but can be listed as follows: polyethylene glycol, polypropylene glycol, polytetramethylene glycol, random copolymers of polyethylene glycol and polypropylene glycol, random copolymers of polyethylene glycol and polytetramethylene glycol, random copolymers of polyethylene glycol and polypropylene glycol, random copolymers of polyethylene glycol and polypropylene glycol, block copolymers of polyethylene glycol and polypropylene glycol, triblock copolymers of polyethylene glycol and polypropylene glycol, etc. Among these, polyethylene glycol and polypropylene glycol are preferred, with polyethylene glycol being even more preferred.

[0048] The weight average molecular weight (Mw) of the polyolefin glycol is preferably 100 or more, more preferably 150 or more, and even more preferably 200 or more. The weight average molecular weight (Mw) of the polyolefin glycol is preferably 30,000 or less, more preferably 10,000 or less, and even more preferably 1,000 or less. That is, the weight average molecular weight (Mw) of the polyolefin glycol is preferably 100 or more and 30,000 or less; more preferably 150 or more and 10,000 or less; even more preferably 150 or more and 1,000 or less; particularly preferably 200 or more and 1,000 or less; and best preferably 200 or more and 350 or less.

[0049] Furthermore, in this specification, the weight-average molecular weight of the polyolefin glycol can be determined by gel permeation chromatography (GPC) using polyethylene glycol as a standard. Detailed determination methods are described in the examples.

[0050] The content (concentration) of polyolefin diol in the grinding composition is not particularly limited, but is preferably 0.001% by mass or more relative to the total mass of the grinding composition, more preferably 0.01% by mass, and even more preferably 0.03% by mass or more. Furthermore, the content of polyolefin diol in the grinding composition is preferably 10% by mass or less relative to the total mass of the grinding composition, more preferably 5% by mass or less, even more preferably 1% by mass or less, particularly preferably 0.2% by mass or less, and best preferably 0.15% by mass or less. That is, the content of polyolefin diol is preferably 0.001% by mass or more and 10% by mass or less; more preferably 0.01% by mass or more and 5% by mass or less; even more preferably 0.03% by mass or more and 1% by mass or less; particularly preferably 0.03% by mass or more and 0.2% by mass or less; and best preferably 0.03% by mass or more and 0.15% by mass or less. If the content of polyolefin glycol is within such a range, the Group 13 element layer can be ground at a higher grinding speed. Furthermore, the grinding speed of the Group 13 element layer becomes higher than that of other materials (the selectivity becomes higher).

[0051] [Acid] The grinding composition of the present invention comprises an acid. Examples of acids include formic acid, acetic acid, propionic acid, butyric acid, 2-hydroxyisobutyric acid (HBA), valeric acid, hexanoic acid, heptanoic acid, caprylic acid, nonanoic acid, caprylic acid, lauric acid, myristic acid, palmitic acid, heptadecanic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, eicosapentaenoic acid, docosahexaenoic acid, eicosapentaenoic acid, lactic acid, malic acid, citric acid, benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, salicylic acid, gallic acid, mellitusic acid, cinnamic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, fumaric acid, maleic acid, aconitic acid, amino acids, anthraquinone acid, and nitrocarboxylic acid. Carboxylic acids such as methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, 10-camphorsulfonic acid, hydroxyethylsulfonic acid, taurine, etc.; inorganic acids such as carbonic acid, hydrochloric acid, nitric acid, phosphoric acid, hypophosphoric acid, phosphorous acid, phosphonic acid, sulfuric acid, boric acid, hydrofluoric acid, orthophosphoric acid, pyrophosphoric acid, polyphosphoric acid, metaphosphoric acid, hexametaphosphoric acid, etc.; and so on. These acids can be used alone or in combination of two or more.

[0052] From the viewpoint of further enhancing the effect of the present invention, the aforementioned acid is preferably at least one selected from the group consisting of acids having a nitrate group and acids having a sulfonic acid group. The acid having a nitrate group is more preferably nitric acid. The acid having a sulfonic acid group is more preferably 10-camphorsulfonic acid or hydroxyethylsulfonic acid.

[0053] The acid content (concentration) in the grinding composition is not particularly limited, but is preferably 0.001% by mass or more, and more preferably 0.005% by mass or more, relative to the total mass of the grinding composition. Furthermore, the acid content in the grinding composition is preferably 10% by mass or less, and more preferably 5% by mass or less, relative to the total mass of the grinding composition. If the acid content is within such a range, the Group 13 element layer can be ground at a higher grinding speed. Furthermore, the grinding speed of the Group 13 element layer becomes higher than that of other materials (the selectivity becomes higher).

[0054] [Dispersion Medium] The grinding composition of the present invention preferably comprises a dispersion medium that disperses the components. Examples of dispersion media include, but are not limited to, water; alcohols such as methanol, ethanol, and ethylene glycol; ketones such as acetone; and mixtures thereof. Water is preferably used as the dispersion medium. That is, according to a preferred embodiment of the present invention, the dispersion medium comprises water. According to a more preferred embodiment of the present invention, the dispersion medium is substantially composed of water. Furthermore, the term "substantially" as used above means that, within the scope that enables the effects of the present invention to be achieved, a dispersion medium other than water may be included. More specifically, the dispersion medium is preferably formed of a dispersion medium other than 90% by mass or more and 100% by mass of water and 0% by mass or more and 10% by mass of water, and more preferably formed of a dispersion medium other than 99% by mass or more and 100% by mass of water and 0% by mass or more and 1% by mass of water. Water is the most preferred dispersion medium.

[0055] From the viewpoint of not hindering the function of the components contained in the grinding composition, the dispersion medium is preferably water that is as free of impurities as possible. Specifically, it is more preferably pure water, ultrapure water, or distilled water that has been filtered to remove foreign matter after impurity ions have been removed using an ion exchange resin.

[0056] [pH] The pH of the grinding composition of the present invention is preferably 1 or higher, and more preferably 2 or higher. Furthermore, the pH is preferably less than 6, and more preferably 5 or lower. That is, the pH of the grinding composition of the present invention is preferably 1 or higher and less than 6; more preferably 2 or higher and less than 5; further preferably 2 or higher and less than 4; and especially preferably 2 or higher and less than 4.

[0057] Furthermore, using a pH meter (for example, a glass electrode type hydrogen ion concentration indicator (model: F-23) manufactured by Horiba Manufacturing Co., Ltd.), after three-point calibration using standard buffer solutions (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)), the glass electrode is placed in the grinding composition, and after more than 2 minutes, the stable value can be measured, thereby obtaining the pH of the grinding composition.

[0058] The grinding composition of the present invention contains abrasive particles, polyolefin glycol and acid as essential components. However, when it is difficult to obtain the desired pH value by means of these components alone, a pH adjuster may be added to adjust the pH without impairing the effect of the present invention.

[0059] The pH adjuster is preferably alkaline, and can be either an inorganic or organic compound. The pH adjuster can be used alone or in combination of two or more.

[0060] Specific examples of bases that can be used as pH adjusters include, for example, hydroxides or salts of Group 1 elements, hydroxides or salts of Group 2 elements, quaternary ammonium hydroxide or its salts, amines, etc. Specific examples of salts include carbonates, bicarbonates, sulfates, acetates, etc.

[0061] The amount of pH adjuster added is not particularly limited and can be appropriately adjusted to give the grinding composition the desired pH.

[0062] [Other ingredients] Without impairing the effects of the present invention, the grinding composition of the present invention may further contain known additives for grinding compositions, such as oxidants, chelating agents, preservatives, and fungicides.

[0063] [Method for manufacturing the grinding composition] The method for manufacturing the grinding composition of the present invention is not particularly limited. For example, it can be obtained by stirring and mixing cationic modified silica, polyolefin glycol, acid, and other components added as needed in a dispersion medium (e.g., water). Details of each component are as described above.

[0064] There is no particular limitation on the temperature when mixing the components, but it is best to use a temperature between 10°C and 40°C. Heating can also be used to increase the dissolution rate. Furthermore, there is no particular limitation on the mixing time as long as the components can be mixed evenly.

[0065] [Polishing Method and Semiconductor Substrate Manufacturing Method] As described above, the polishing composition of the present invention is suitable for polishing objects having a layer of Group 13 elements. Therefore, the present invention provides a polishing method for polishing an object having a layer having a Group 13 element content of greater than 40% by mass using the polishing composition of the present invention. Furthermore, the present invention provides a semiconductor substrate manufacturing method comprising polishing a semiconductor substrate having a Group 13 element content of greater than 40% by mass using the above-described polishing method.

[0066] As a grinding device, a general grinding device can be used, which is equipped with a support for gripping a substrate or the like with the object to be ground, a motor with a variable rotation speed, and a grinding plate for attaching a grinding pad (grinding cloth).

[0067] As the abrasive pad, general non-woven fabric, polyurethane, porous fluoropolymer, etc., can be used without particular limitation. Preferably, the abrasive pad is grooved to collect the abrasive liquid.

[0068] Regarding polishing conditions, for example, the rotational speed of the polishing disc is preferably 10 rpm (0.17 s⁻¹) or more, or 500 rpm (8.33 s⁻¹). The pressure applied to the substrate with the object to be polished (polishing pressure) is preferably 0.5 psi (3.4 kPa) or more, or 10 psi (68.9 kPa). The method of supplying the polishing composition to the polishing pad is not particularly limited; for example, a method of continuously supplying the polishing composition using a pump or the like can be used. This supply amount is not limited, but it is preferable that the surface of the polishing pad is always covered by the polishing composition of the present invention.

[0069] After grinding, the substrate is washed in running water, and the water droplets attached to the substrate are removed and dried using a rotary dryer or the like, thereby obtaining a substrate having a metal layer.

[0070] The grinding composition of the present invention can be a single-liquid type or a multi-liquid type, such as a two-liquid type. Furthermore, the grinding composition of the present invention can be prepared by using a dilution solution of the original grinding composition diluted with water or the like, for example, diluted 10 times or more.

[0071] Although embodiments of the present invention have been described in detail, these are merely illustrative and exemplary examples, not limiting examples. It should be understood that the scope of the present invention should be interpreted in accordance with the appended claims.

[0072] The present invention includes the following embodiments and forms.

[0073] [1] A grinding composition for grinding an object having a layer containing more than 40% by mass of a group 13 element, the grinding composition comprising cationic modified silica, polyolefin glycol and acid.

[0074] [2] The grinding composition as described in [1], wherein the average primary particle size of the above-mentioned cationic modified silicon oxide is 5 nm or more and 30 nm or less.

[0075] [3] The grinding composition described in [2] wherein the ratio of the average secondary particle size of the cationic modified silicon oxide to the average primary particle size of the cationic modified silicon oxide (average secondary particle size / average primary particle size) is 1.2 or more and 3 or less.

[0076] [4] The grinding composition described in any one of [1] to [3], wherein the interface potential of the cationic modified silicon oxide in the grinding composition is 5 mV or more and 60 mV or less.

[0077] [5] The grinding composition described in any one of [1] to [4], wherein the polyolefin diol is polyethylene glycol.

[0078] [6] The grinding composition described in any one of [1] to [5], wherein the weight average molecular weight of the polyolefin diol is 100 or more and 30,000 or less.

[0079] [7] The grinding composition described in any one of [1] to [6], wherein the acid is at least one selected from the group consisting of acids having a nitrate group and acids having a sulfonic acid group.

[0080] [8] The grinding composition described in any of [1] to [7], wherein the pH is 1 or higher and less than 6.

[0081] [9] A grinding method comprising the step of grinding an object having a layer having a content of more than 40% by mass of a group 13 element using a grinding composition as described in any one of [1] to [8].

[0082]

[10] A method for manufacturing a semiconductor substrate includes polishing a semiconductor substrate having a layer having a content of more than 40% by mass of a group 13 element by a polishing method as described in [9]. [Example]

[0083] The present invention will be described in more detail using the following embodiments and comparative examples. However, the technical scope of the present invention is not limited to the following embodiments. Also, unless otherwise stated, "%" and "parts" respectively represent "mass %" and "parts by mass".

[0084] <Average primary particle size of abrasive particles> The average primary particle size of abrasive particles is calculated by measuring the specific surface area of ​​silicon oxide particles and the density of abrasive particles using the BET method, as determined by the "Flow Sorb II 2300" manufactured by Micromeritics.

[0085] <Average Secondary Particle Size of Abrasive Particles> The average secondary particle size of abrasive particles is the volume average particle size (arithmetic mean particle size based on volume; Mv) measured using a dynamic light scattering type particle size / particle size distribution device UPA-UTI151 (manufactured by Nikkiso Co., Ltd.).

[0086] <Average Associativity of Abrasive Particles> The average association of abrasive particles is calculated by dividing the average secondary particle size of the abrasive particles by the average primary particle size of the abrasive particles.

[0087] <Interfacial Potential of Abrasive Particles> The interfacial potential of the abrasive particles in the abrasive composition is determined by supplying the abrasive composition to a Zetasizer Nano instrument manufactured by Malvern Panalytical Co., Ltd., and measuring it using the laser Doppler method (electrophoretic light scattering method) at a measurement temperature of 25°C. The obtained data is then analyzed and calculated using the Smoluchowski formula.

[0088] <Weight Average Molecular Weight of Polyolefin Glycols> The weight average molecular weight of polyolefin glycols was determined by gel permeation chromatography (GPC) using polyethylene glycol as a standard. Detailed conditions are as follows: GPC Apparatus: Shimadzu Corporation, Model: Prominence + ELSD Detector (ELSD-LTII) Column: VP-ODS (Shimadzu Corporation, Manufacturer) Mobile Phase A: Methanol (MeOH) B: 1% aqueous acetic acid Flow Rate: 1 mL / min Detector: ELSD; Temperature: 40°C; Gain 8; Nitrogen: 350 kPa Oven Temperature: 40°C Injection Volume: 40 μL

[0089] <pH of the grinding composition> The pH of the grinding composition is determined by using a glass electrode type hydrogen ion concentration indicator (manufactured by Horiba Manufacturing Co., Ltd.; model: F-23) and performing three-point calibration using standard buffer solutions (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)). The glass electrode is then placed in the grinding composition for at least 2 minutes, and the stable value is measured as the pH value of the grinding composition.

[0090] [Preparation of the Grinding Composition] (Example 1) The method described in Example 1 of Japanese Patent Application Publication No. 2005-162533 was carried out in the same manner as described in Example 1. γ-aminopropyltriethoxysilane (APTES) was used as a silane coupling agent and its concentration was set to 2 mmol (2 mM) relative to 1 L of a methanol solution of silica sol (silica concentration = 20% by mass) to prepare cocoon-shaped cationic modified colloidal silica with an average primary particle size of 24.6 nm, an average secondary particle size of 47.2 nm, and an average degree of association of 1.92.

[0091] To obtain a mixture, pure water as a dispersion medium was added at room temperature (25°C) in a manner that the cationic modified colloidal silicon oxide obtained above as abrasive particles had a final concentration of 4% by mass and the polyethylene glycol (PEG; manufactured by Fuji Film and Koimitsu Pharmaceutical Co., Ltd.; weight average molecular weight: 200) as a polyolefin diol had a final concentration of 0.05% by mass.

[0092] Then, nitric acid as an acid is added to the mixture to make the final concentration 0.0252% by mass, and the mixture is stirred and mixed at room temperature (25°C) for 30 minutes to prepare a grinding composition.

[0093] The pH of the obtained grinding composition is 2.5. Furthermore, the interfacial potential of the cationic modified colloidal silicon oxide in the obtained grinding composition was measured according to the above method, and the result was +27 mV. In addition, the particle size of the cationic modified colloidal silicon oxide in the grinding composition is the same as that of the cationic modified colloidal silicon oxide used.

[0094] (Examples 2-21, Comparative Examples 1-4) The particle size and shape of the abrasive particles, the amount of APTES, the content of the abrasive particles, the type and content of the polyolefin diol, and the type and content of the acid were changed as shown in Table 1 below. Otherwise, the abrasive composition was prepared in the same manner as in Example 1.

[0095] "-" in Table 1 below indicates that this agent was not used. Comparative Examples 1-2 are examples that use unmodified colloidal silicon oxide and do not use polyolefin glycol. Comparative Example 4 is an example that does not use polyolefin glycol.

[0096] The composition of each grinding component is shown in Table 1 below.

[0097] [Table 1] abrasive particles Polyolefin diol acid pH of grinding composition average Primary particle size (nm) average Secondary particle size (nm) average Associativity shape APTES usage (mM) interface Potential (mV) content (quality%) type Mw content (quality%) type content (quality%) Example 1 24.6 47.2 1.92 cocoon 2.0 +27 4.0 PEG 200 0.25 Nitric acid 0.0252 2.5 Example 2 33.3 52.0 1.56 spherical 2.0 +30 1.0 PEG 200 0.25 Nitric acid 0.0280 2.5 Example 3 33.3 52.0 1.56 spherical 2.0 +30 4.0 PEG 200 0.25 Nitric acid 0.0320 2.5 Example 4 76.3 120.0 1.57 cocoon 1.7 +53 4.0 PEG 200 0.25 Nitric acid 0.0252 2.5 Example 5 17.0 27.0 1.59 spherical 2.0 +22 1.0 PEG 200 0.25 Acetic acid 3.3150 2.5 Example 6 15.0 35.0 2.33 cocoon 1.3 +19 1.0 PEG 200 0.25 Hydroxyethylsulfonic acid 0.0520 2.5 Example 7 24.6 47.2 1.92 cocoon 2.0 +27 1.0 PEG 200 0.25 Nitric acid 0.0252 2.5 Example 8 24.6 47.2 1.92 cocoon 2.0 +27 1.0 PEG 200 0.25 Hydroxyethylsulfonic acid 0.0520 2.5 Example 9 17.0 27.0 1.59 spherical 2.0 +22 1.0 PEG 200 0.25 Nitric acid 0.0258 2.5 Example 10 17.0 27.0 1.59 spherical 2.0 +22 1.0 PEG 200 0.25 Hydroxyethylsulfonic acid 0.0520 2.5 Example 11 17.0 27.0 1.59 spherical 2.0 +22 4.0 PEG 200 0.25 Hydroxyethylsulfonic acid 0.0520 2.5 Example 12 17.0 27.0 1.59 spherical 2.0 +22 1.0 PEG 200 0.25 2-Hydroxyisobutyric acid 2.8960 2.5 Example 13 17.0 27.0 1.59 spherical 2.0 +22 1.0 PEG 200 0.25 10-Camphorsulfonic acid 0.1190 2.5 Example 14 17.0 27.0 1.59 spherical 2.0 +20 1.0 PEG 200 0.25 Hydroxyethylsulfonic acid 0.0220 3.0 Example 15 17.0 27.0 1.59 spherical 2.0 +19 1.0 PEG 200 0.25 Hydroxyethylsulfonic acid 0.0150 4.0 Example 16 17.0 27.0 1.59 spherical 2.0 +10 1.0 PEG 200 0.25 Hydroxyethylsulfonic acid 0.0100 5.0 Example 17 17.0 27.0 1.59 spherical 2.0 +22 1.0 PEG 200 0.10 Hydroxyethylsulfonic acid 0.0520 2.5 Example 18 17.0 27.0 1.59 spherical 2.0 +22 1.0 PEG 200 0.03 Hydroxyethylsulfonic acid 0.0520 2.5 Example 19 17.0 27.0 1.59 spherical 2.0 +22 1.0 PEG 600 0.10 Hydroxyethylsulfonic acid 0.0520 2.5 Example 20 17.0 27.0 1.59 spherical 2.0 +22 1.0 PEG 2000 0.10 Hydroxyethylsulfonic acid 0.0520 2.5 Example 21 17.0 27.0 1.59 spherical 3.0 +23 1.0 PEG 400 0.10 Hydroxyethylsulfonic acid 0.0520 2.5 Comparative Example 1 17.0 27.0 1.59 spherical - +1 1.0 - - - Nitric acid 0.0300 2.5 Comparative Example 2 24.6 47.2 1.92 cocoon - +3 1.0 - - - Nitric acid 0.0260 2.5 Comparative Example 3 17.0 27.0 1.59 spherical 2.0 -57 1.0 PEG 200 0.25 NH4OH 0.2020 10.0 Comparative Example 4 76.3 120.0 1.57 cocoon 1.7 +53 4.0 - - - Nitric acid 0.0252 2.5

[0098] [Evaluation] The surfaces of objects to be polished were polished using the polishing compositions prepared above under the following conditions. The objects to be polished were silicon wafers (300 mm, blanket-coated wafers; manufactured by Advantech Inc.) with a boron (B)-silicon (Si) film (50% by mass of boron (B): 50% by mass of silicon (Si)) film with a thickness of 5000 Å, silicon wafers (300 mm, blanket-coated wafers; manufactured by Advantech Inc.) with a thickness of 2500 Å of SiN (silicon nitride) film, and silicon wafers (300 mm, blanket-coated wafers; manufactured by Advanced Materials Technology Inc.) with a thickness of 3600 Å of TiN (titanium nitride) film. (Grinding apparatus and grinding conditions) Grinding apparatus: Ebara Manufacturing Co., Ltd.; FREX300E CMP single-sided grinding apparatus for 300 mm Grinding pad: Fujibo Holdings, Inc.; H800 non-woven pad Grinding pressure: 3.0 psi (1 psi = 6894.76 Pa) Grinding disc rotation speed: 90 rpm Carrier rotation speed: 91 rpm Grinding composition supply method: Flowing Grinding composition supply rate: 250 mL / min Grinding time: 60 seconds.

[0099] (Grinding Speed) For B-Si and SiN films, the thickness before and after grinding was determined using an optical film thickness gauge (ASET-f5x: manufactured by KLA Tencor). For TiN films, the thickness before and after grinding was determined using a sheet resistance gauge (VR-120: manufactured by Kokusai Electric Semiconductor Service Co., Ltd.). The grinding speed for each object was calculated by dividing [(thickness before grinding) - (thickness after grinding)] by the grinding time.

[0100] (Grinding speed selection ratio) The selection ratio of each grinding speed is obtained by the following formula: B-Si / SiN = B-Si grinding speed (Å / min) / SiN grinding speed (Å / min) B-Si / TiN=B-Si grinding speed (Å / min) / TiN grinding speed (Å / min).

[0101] The above evaluation results are shown in Table 2 below.

[0102] [Table 2] Grinding speed (Å / min) Grinding speed selectivity B-Si SiN TiN B-Si / SiN B-Si / TiN Example 1 1607 101 212 15.9 7.6 Example 2 642 17 46 37.8 14.0 Example 3 884 51 110 17.3 8.0 Example 4 500 120 170 4.2 2.9 Example 5 522 11 36 47.5 14.5 Example 6 886 15 44 59.1 20.1 Example 7 1274 20 79 63.7 16.1 Example 8 1530 25 66 61.2 23.2 Example 9 805 2 32 402.5 25.2 Example 10 966 3 27 322 35.8 Example 11 985 31 61 31.8 16.1 Example 12 859 12 32 71.6 26.8 Example 13 844 3 30 281.3 28.1 Example 14 911 2 twenty two 455.5 41.4 Example 15 845 2 91 422.5 9.3 Example 16 761 4 55 190.3 13.8 Example 17 1106 2 twenty three 553.0 48.1 Example 18 1461 2 twenty three 730.5 63.5 Example 19 722 18 63 40.1 11.5 Example 20 610 13 twenty one 46.9 29.0 Example 21 500 29 26 17.2 19.2 Comparative Example 1 100 1 - 100.0 - Comparative Example 2 79 3 - 26.3 - Comparative Example 3 twenty one 2 13 21.0 1.6 Comparative Example 4 456 117 155 3.9 2.9

[0103] As can be seen from Table 2 above, the grinding speed of the B-Si film is increased compared with that of the comparative example grinding composition. Furthermore, it can be seen that the ratio (selectivity ratio) of the grinding speed of the B-Si film to the grinding speed of other materials is higher compared with that of the comparative example grinding composition.

[0104] This application is based on Japanese Patent Application No. 2021-45750, filed on March 19, 2021, the disclosure of which is incorporated herein by reference in its entirety. [Simplified Explanation of the Diagram]

[0010] None.

Claims

1. A grinding composition for grinding an object having a layer containing 40% or more of a Group 13 element, comprising cationic modified silica, polyalkylene glycol, and an acid, wherein, The pH is below 3, and the above acids have sulfonic acid groups.

2. The grinding composition as described in claim 1, wherein, The average primary particle size of the aforementioned cationic modified silicon oxide is greater than 5 nm and less than 30 nm.

3. The grinding composition as described in claim 2, wherein, The ratio of the average secondary particle size of the aforementioned cationic modified silicon oxide to the aforementioned average primary particle size (average secondary particle size / average primary particle size) is 1.2 or more and 3 or less.

4. The grinding composition as described in claim 1, wherein, The interfacial potential of the cationic modified silicon oxide in the above-mentioned grinding composition is 5mV or more and 60mV or less.

5. The grinding composition as described in claim 1, wherein, The aforementioned polyalkylene glycol is polyethylene glycol.

6. The grinding composition as described in claim 1, wherein, The weight average molecular weight of the aforementioned polyalkylene glycols is above 100 and below 30,000.

7. The grinding composition as described in claim 1, wherein, The weight average molecular weight of the aforementioned polyalkylene glycols is above 150 and below 350.

8. The grinding composition as described in claim 1, wherein, The dispersion medium consists of only water.

9. A grinding method comprising the step of grinding an object having a layer containing 40% by mass or more of a Group 13 element using a grinding composition as described in claim 1.

10. A method for manufacturing a semiconductor substrate, comprising polishing a semiconductor substrate having a layer having a content of 40% by mass or more of a group 13 element by the polishing method described in claim 9.