Polishing composition, polishing method, and method for manufacturing semiconductor substrate

Abstract

The present application relates to a polishing composition, a polishing method, and a manufacturing method of a semiconductor substrate. Provided is a polishing composition that can polish a layer having a content of Group 13 element of 40% by mass or more at a high polishing rate. Provided is a polishing composition for polishing a polishing object having a layer with a content of Group 13 element exceeding 40% by mass, the polishing composition comprising a cation-modified silica, a 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. Background Technology

[0002] In recent years, with the increasing use of multilayer wiring on semiconductor substrates, chemical mechanical polishing (CMP) technology has been employed in device manufacturing to planarize semiconductor substrates. 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 dioxide, aluminum oxide, and cerium oxide, as well as corrosion inhibitors and surfactants. The workpiece can be silicon, polysilicon, silicon oxide film, silicon nitride, wiring, plugs, etc., formed from 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 comprising the following steps: a step of pre-polishing using a pre-polishing composition containing abrasive particles, alkali, a water-soluble polymer and water; and a step of fine polishing using a fine 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] Recently, a new requirement has been put forward for polishing semiconductor substrates that use layers containing at least 40% by mass of Group 13 elements. Such a requirement has been virtually unexplored before.

[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] 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 group 13 elements is higher than that of other materials (i.e., the selectivity is high).

[0008] Solution for solving the problem

[0009] To address the aforementioned new challenges, the inventors conducted repeated and in-depth research. Their findings revealed that a grinding composition comprising cationic modified silica, polyalkylene glycol, and an acid effectively solved these challenges, thus completing this invention.

[0010] That is, the present invention is a grinding composition for grinding an object having a layer containing 40% or more of group 13 elements, the grinding composition comprising cationic modified silica, polyalkylene glycol and acid. Detailed Implementation

[0011] This invention provides a grinding composition for grinding a workpiece having a layer containing 40% or more of Group 13 elements. The grinding composition comprises cationic modified silica, polyalkylene glycol, and an acid. One embodiment of the grinding composition of this invention, having this configuration, can grind layers containing 40% or more of Group 13 elements at high grinding speeds. Furthermore, another embodiment of the grinding composition of this invention exhibits a higher grinding speed for layers containing 40% or more of Group 13 elements than for other materials (i.e., higher selectivity).

[0012] The embodiments of the present invention will now be described. It should be noted that the present invention is not limited to the following embodiments.

[0013] Unless otherwise specified, the operation and physical property measurements shall be performed at room temperature (above 20°C and below 25°C) and relative humidity (above 40%RH and below 50%RH).

[0014] [Object to be ground]

[0015] The grinding 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). Examples of group 13 elements include boron (B), aluminum (Al), gallium (Ga), and indium (In). A group 13 element may be a single element or a combination of two or more elements.

[0016] The group 13 layer can include elements other than those in group 13. Examples of such elements include silicon (Si), hydrogen (H), nitrogen (N), oxygen (O), carbon (C), phosphorus (P), and germanium (Ge). These other elements can be a single element or a combination of two or more.

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

[0018] In addition to the group 13 element layer, the grinding object of the present invention may also include other materials. 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, elemental metals, SiGe, etc.

[0019] Examples of grinding objects containing silica include TEOS (Tetraethyl Orthosilicate) type silica surfaces (hereinafter also referred to as "TEOS" or "TEOS film"), HDP (High Density Plasma) films, USG (Undoped Silicate Glass) films, PSG (Phosphorus Silicate Glass) films, BPSG (Boron-Phospho Silicate Glass) films, and RTO (Rapid Thermal Oxidation) films, which are produced using tetraethyl orthosilicate as a precursor.

[0020] Examples of metallic elements include tungsten, copper, cobalt, hafnium, nickel, gold, silver, platinum, palladium, rhodium, ruthenium, iridium, and osmium.

[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. Examples of such materials include polycrystalline silicon doped with p-type impurities and amorphous silicon doped with p-type impurities.

[0022] [Cationic modified silica]

[0023] The grinding composition of the present invention comprises cationic modified silica (silica having cationic groups) as abrasive particles. Cationic modified silica can be used alone or in combination of two or more types. Furthermore, commercially available or synthetic cationic modified silica can be used.

[0024] As a cationic modified silica, cationic modified colloidal silica (colloidal silica having cationic groups) is preferred.

[0025] Examples of methods for manufacturing colloidal silica include the sodium silicate method and the sol-gel method. Colloidal silica manufactured by any method is suitable for use as abrasive grains in this invention. However, from the viewpoint of reducing metallic impurities, colloidal silica manufactured by the sol-gel method is preferred. Colloidal silica manufactured by the sol-gel method is preferred because it contains less content of diffusible metallic impurities and corrosive ions such as chloride ions in semiconductors. The manufacture of colloidal silica based on the sol-gel method can be carried out using conventionally known methods. Specifically, a hydrolyzable silicon compound (e.g., alkoxysilane or its derivatives) is used as a raw material and subjected to a hydrolysis / condensation reaction to obtain colloidal silica.

[0026] Here, cationic modification refers to the state in which cationic groups (e.g., amino or quaternary ammonium groups) are bonded to the surface of silica (preferably colloidal silica). Furthermore, according to a preferred embodiment of the invention, the cationic modified silica particles are amino-modified silica particles, more preferably amino-modified colloidal silica particles. Based on the above embodiments, the aforementioned effects can be further improved.

[0027] To cationicly modify silica (colloidal silica), a silane coupling agent having cationic groups (e.g., amino or quaternary ammonium groups) is added to the silica (colloidal silica) and reacted at a specified temperature for a specified time. In a preferred embodiment of the present invention, cationically modified silica is formed by immobilizing an amino-containing silane coupling agent or a quaternary ammonium-containing silane coupling agent on the surface of silica (more preferably colloidal silica).

[0028] At this time, the silane coupling agent used can be, for example, the silane coupling agent described in Japanese Patent Application Publication No. 2005-162533. Specifically, examples include silane coupling agents such as N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltriethoxysilane, γ-aminopropyltriethoxysilane ((3-aminopropyl)triethoxysilane), γ-aminopropyltrimethoxysilane, γ-triethoxysilyl-N-(α,γ-dimethyl-butylidene)propylamine, N-phenyl-γ-aminopropyltrimethoxysilane, hydrochloride salts of N-(vinylbenzyl)-β-aminoethyl-γ-aminopropyltriethoxysilane, octadecyldimethyl-(γ-trimethoxysilylpropyl)-ammonium chloride, and N-trimethoxysilylpropyl-N,N,N-trimethylammonium chloride. From the perspective of good reactivity with colloidal silica, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltriethoxysilane, γ-aminopropyltriethoxysilane, and γ-aminopropyltrimethoxysilane are preferred. It should be noted that in this invention, a single silane coupling agent may be used alone, or two or more may be used in combination.

[0029] It should be noted that the silane coupling agent can be added directly or diluted with a hydrophilic organic solvent or pure water before being added to silica (colloidal silica). Diluting with a hydrophilic organic solvent or pure water can inhibit the formation of aggregates. When diluting the silane coupling agent with a hydrophilic organic solvent or pure water, the silane coupling agent can be diluted with the hydrophilic organic solvent or pure water at a concentration preferably between 0.01 g and 1 g, more preferably between 0.1 g and 0.7 g, in 1 L of hydrophilic organic solvent or pure water. There are no particular limitations on the hydrophilic organic solvent; examples include methanol, ethanol, isopropanol, butanol, and other lower alcohols.

[0030] Furthermore, the amount of cationic groups introduced onto the surface of silica (colloidal silica) can be adjusted by regulating the amount of silane coupling agent added. The amount of silane coupling agent is not particularly limited, but 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.

[0031] There is no particular limitation on the processing temperature when using silane coupling agents to cationic modify silica (colloidal silica). It is acceptable to use a temperature range from room temperature (e.g., 25°C) to around the boiling point of the dispersion medium used to disperse silica (colloidal silica). Specifically, it is set to above 0°C and below 100°C, and preferably above room temperature (e.g., 25°C) and below 90°C.

[0032] There are no particular limitations on the shape of cationic modified silica. It can be spherical (hereinafter also referred to as spherical) or non-spherical. Specific examples of non-spherical shapes include triangular prisms, quadrangular prisms and other polyhedral shapes, cylinders, straw bag shapes (where the central part of a cylinder is further expanded than the ends), ring shapes that penetrate the central part of a disc, plate shapes, so-called cocoon shapes with a constricted neck in the central part, so-called associated spherical shapes where multiple particles are integrated, so-called konpeito shapes with multiple protrusions on the surface, rugby ball shapes, and various other shapes, without particular limitations.

[0033] The average primary particle size of the cationic modified silica is preferably 1 nm or more, more preferably 3 nm or more, and even more preferably 5 nm or more. As the average primary particle size of the cationic modified silica increases, the grinding speed of the group 13 element layer further increases. Furthermore, the average primary particle size of the cationic modified silica is preferably 100 nm or less, more preferably 50 nm or less, and even more preferably 30 nm or less. As the average primary particle size of the cationic modified silica decreases, the grinding speed of the group 13 element layer becomes higher than that of other materials (the selectivity becomes higher).

[0034] That is, the average primary particle size of the cationic modified silica 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. It should be noted that the average primary particle size of the cationic modified silica can be calculated, for example, based on the specific surface area (SA) and density of the cationic modified silica calculated by the BET method. More specifically, the average primary particle size of the cationic modified silica is a value measured by the method described in the examples.

[0035] Furthermore, the average secondary particle size of the cationic modified silica 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 silica increases, the resistance during grinding decreases, making stable grinding possible. Additionally, the average secondary particle size of the cationic modified silica 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 silica decreases, the surface area per unit mass of the cationic modified silica increases, the contact frequency with the object being ground increases, and the grinding speed further increases. That is, the average secondary particle size of the cationic modified silica 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. It should be noted that the average secondary particle size of the cationic modified silica is a value measured by the method described in the examples.

[0036] The ratio of the average secondary particle size to the average primary particle size of the cationic modified silica (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 silica increases, the grinding speed of the group 13 element layer further increases. Furthermore, the average degree of association of the cationic modified silica 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 silica 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 silica 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.

[0037] It should be noted that the average degree of association of cationic modified silica is obtained by dividing the average secondary particle size of cationic modified silica by the average primary particle size.

[0038] There is no particular upper limit to the aspect ratio of the cationic modified silica in the polishing composition, but it is preferably below 2.0, more preferably below 1.8, and even more preferably below 1.5. Within this range, defects on the surface of the object being polished can be further reduced. It should be noted that the aspect ratio is the average value obtained by dividing the length of the longest side of the smallest rectangle circumscribed in an image of the cationic modified silica particles acquired using a scanning electron microscope by the length of the shortest side of the same rectangle, which can be calculated using general image analysis software. There is no particular lower limit to the aspect ratio of the cationic modified silica in the polishing composition, but it is preferably 1.0 or higher.

[0039] In the particle size distribution of cationic modified silica determined by laser diffraction scattering, the lower limit of the ratio of the diameter of the particle (D90) when the cumulative particle weight from the fine particle side reaches 90% of the total particle weight to the diameter of the particle (D50) when it reaches 50% of the total particle weight, i.e., D90 / D50, is not particularly limited, but preferably 1.1 or more, more preferably 1.2 or more, and even more preferably 1.3 or more, is preferred. Furthermore, in the particle size distribution of the cationic modified silica in the grinding composition determined by laser diffraction scattering, the upper limit of the ratio of the diameter of the particle (D90) when the cumulative particle weight from the fine particle side reaches 90% of the total particle weight to the diameter of the particle (D50) when it reaches 50% of the total particle weight, D90 / D50, is not particularly limited, but preferably 2.0 or less, more preferably 1.7 or less, and even more preferably 1.5 or less, is preferred. Within this range, defects on the surface of the object being ground can be further reduced.

[0040] The size of cationic modified silica (average primary particle size, average secondary particle size, aspect ratio, D90 / D50, etc.) can be appropriately controlled according to the choice of manufacturing method of cationic modified silica.

[0041] The lower limit of the zeta potential of the cationic modified silica in the polishing 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 silica in the polishing 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 grains in the polishing 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.

[0042] If the material is cationic modified silica with the aforementioned Zeta potential, the group 13 element layer can be milled at a higher milling speed. Furthermore, the milling speed of the group 13 element layer becomes higher than that of other materials (the selectivity becomes higher).

[0043] In this specification, the Zeta potential of cationic modified silica is a value measured by the method described in the examples. The Zeta potential of cationic modified silica can be adjusted according to the amount of cationic groups present in the cationic modified silica, the pH of the grinding composition, etc.

[0044] The content (concentration) of cationic modified silica 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, further preferably 0.5% by mass or more, and particularly preferably more than 0.5% by mass, relative to the total mass of the grinding composition. Furthermore, the upper limit of the content of cationic modified silica in the grinding composition is preferably 10% by mass or less, more preferably 5% by mass or less, further preferably 4% by mass or less, and particularly preferably less than 4% by mass, relative to the total mass of the grinding composition. That is, the content of cationic modified silica 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, further preferably 0.5% by mass or more and 4% by mass or less, and particularly preferably more than 0.5% by mass or less than 4% by mass, relative to the total mass of the grinding composition.

[0045] If the content of cationic modified silica is within this 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 silica, the content of cationic modified silica refers to their total amount.

[0046] The abrasive composition of the present invention may further include abrasive particles other than cationic modified silica, without impairing the effects of the present invention. These other abrasive particles may be inorganic particles, organic particles, or organic-inorganic composite particles. Specific examples of inorganic particles include particles formed from metal oxides such as unmodified silica, alumina, cerium oxide, and titanium dioxide, as well as silicon nitride particles, silicon carbide particles, and boron nitride particles. Specific examples of organic particles include polymethyl methacrylate (PMMA) particles. These other abrasive particles may be used alone or in combination of two or more. Furthermore, these other abrasive particles may be commercially available or synthetic products.

[0047] [Polyalkylene glycol]

[0048] The grinding composition of the present invention comprises a polyalkylene glycol. The polyalkylene glycol promotes the grinding of the group 13 element layer (increasing grinding speed). A single polyalkylene glycol can be used alone, or two or more can be used in combination. Furthermore, commercially available or synthetic polyalkylene glycols can be used.

[0049] There are no particular limitations on the types of polyalkylene glycols, and examples include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyethylene glycol-polypropylene glycol random copolymers, polyethylene glycol-polytetramethylene glycol random copolymers, polyethylene glycol-polypropylene glycol-polytetramethylene glycol random copolymers, polyethylene glycol-polypropylene glycol-polytetramethylene glycol random copolymers, polyethylene glycol-polypropylene glycol block copolymers, polyethylene glycol-polypropylene glycol-polypropylene glycol triblock copolymers, and polyethylene glycol-polypropylene glycol-polypropylene glycol triblock copolymers. Among these, polyethylene glycol and polypropylene glycol are preferred, and polyethylene glycol is more preferred.

[0050] The weight-average molecular weight (Mw) of the polyalkylene glycol is preferably 100 or more, more preferably 150 or more, and even more preferably 200 or more. Furthermore, the weight-average molecular weight (Mw) of the polyalkylene 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 polyalkylene 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 most preferably 200 or more and 350 or less.

[0051] It should be noted that, in this specification, the weight-average molecular weight of polyalkylene glycols can be determined by gel permeation chromatography (GPC) using polyethylene glycol as a standard. Detailed determination methods are described in the examples.

[0052] The content (concentration) of polyalkylene glycol in the grinding composition is not particularly limited, but is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, and even more preferably 0.03% by mass or more, relative to the total mass of the grinding composition. Furthermore, the content of polyalkylene glycol in the grinding composition is preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 1% by mass or less, particularly preferably 0.2% by mass or less, and most preferably 0.15% by mass or less, relative to the total mass of the grinding composition. That is, the content of polyalkylene glycol 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 most preferably 0.03% by mass or more and 0.15% by mass or less. If the content of polyalkylene glycol is within this range, the Group 13 element layer can be ground at a higher grinding speed. In addition, the grinding speed of the group 13 element layer becomes higher than that of other materials (the selectivity becomes higher).

[0053] [acid]

[0054] 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, octanoic acid, nonanoic acid, decanoic acid, lauric acid, myristic acid, palmitic acid, heptadecanic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, arachidonic acid, docosahexaenoic acid, eicosapentaenoic acid, lactic acid, malic acid, citric acid, benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, salicylic acid, gallic acid, and benzyl hexamethyl phthalate. Carboxylic acids such as cinnamic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, fumaric acid, maleic acid, aconitic acid, amino acids, anthranilic acid, and nitrocarboxylic acids; sulfonic acids such as methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, 10-camphorsulfonic acid, hydroxyethylsulfonic acid, and taurine; and 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, and hexametaphosphoric acid. These acids can be used alone or in combination of two or more.

[0055] From the viewpoint of further improving the effect of the present invention, the 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.

[0056] The acid content (concentration) in the grinding composition is not particularly limited, but is preferably 0.001% by mass or more, 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, more preferably 5% by mass or less, relative to the total mass of the grinding composition. If the acid content is within this range, the group 13 element layer can be ground at a higher grinding speed. In addition, the grinding speed of the group 13 element layer becomes higher than that of other materials (the selectivity becomes higher).

[0057] [Dispersion medium]

[0058] The grinding composition of the present invention preferably includes a dispersion medium for dispersing the components. Examples of dispersion media include water; alcohols such as methanol, ethanol, and ethylene glycol; ketones such as acetone; and mixtures thereof. Among these, water is preferred as the dispersion medium. That is, according to a preferred embodiment of the present invention, the dispersion medium contains water. According to a more preferred embodiment of the present invention, the dispersion medium is substantially composed of water. It should be noted that the above "substantially" means that any dispersion medium other than water may be included as long as the effects of the present invention can be achieved. More specifically, the dispersion medium preferably contains 90% by mass or more and 100% by mass of water and 0% by mass or more and 10% by mass of a dispersion medium other than water, more preferably containing 99% by mass or more and 100% by mass of water and 0% by mass or more and 1% by mass of a dispersion medium other than water. The most preferred dispersion medium is water.

[0059] 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 by ion exchange resin.

[0060] [pH]

[0061] The pH of the grinding composition of the present invention is preferably 1 or higher, more preferably 2 or higher. Furthermore, the pH is preferably lower than 6, more preferably lower than 5. That is, the pH of the grinding composition of the present invention is preferably 1 or higher and lower than 6, more preferably 2 or higher and lower than 5, further preferably 2 or higher and lower than 4, and particularly preferably 2 or higher and lower than 4.

[0062] It should be noted that the pH of the grinding composition can be obtained as follows: using a pH meter (e.g., a glass electrode hydrogen ion concentration indicator manufactured by Horiba Corporation (model: F-23)), after three-point calibration with standard buffer solutions (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)), the glass electrode is placed in the grinding composition, and the value is measured after stabilization for more than 2 minutes.

[0063] The grinding composition of the present invention uses abrasive grains, polyalkylene glycol and acid as essential components. However, since it is difficult to obtain the desired pH from these alone, a pH adjuster may be added to adjust the pH without impairing the effect of the present invention.

[0064] A base is preferred as a pH adjuster; however, both inorganic and organic compounds are acceptable. A single pH adjuster can be used alone, or two or more can be used in combination.

[0065] Specific examples of bases that can be used as pH adjusters include hydroxides or salts of Group 1 elements, hydroxides or salts of Group 2 elements, quaternary ammonium hydroxides or their salts, amines, etc. Specific examples of salts include carbonates, bicarbonates, sulfates, acetates, etc.

[0066] There is no particular limitation on the amount of pH adjuster added; it can be appropriately adjusted in such a way that the grinding composition achieves the desired pH.

[0067] [Other ingredients]

[0068] The grinding composition of the present invention may further contain known additives that can be used in grinding compositions, such as oxidants, complexing agents, preservatives, and fungicides, to a extent that does not impair the effects of the present invention.

[0069] [Method for manufacturing the grinding composition]

[0070] 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, polyalkylene glycol, acid, and other additives as needed in a dispersion medium (e.g., water). Details of each component are as described above.

[0071] There are no particular restrictions on the temperature when mixing the components, but it is preferred to be above 10°C and below 40°C. Heating can be used to improve the dissolution rate. In addition, there are no particular restrictions on the mixing time as long as uniform mixing can be achieved.

[0072] [Grinding methods and semiconductor substrate manufacturing methods]

[0073] As described above, the polishing composition of the present invention is suitable for polishing workpieces having a layer of group 13 elements. Therefore, the present invention provides a polishing method that uses the polishing composition of the present invention to polish a workpiece having a layer containing 40% by mass or more of group 13 elements. Furthermore, the present invention provides a method for manufacturing a semiconductor substrate, comprising: polishing a semiconductor substrate having a layer containing 40% by mass or more of group 13 elements using the above-described polishing method.

[0074] As a grinding device, a general grinding device can be used, which is equipped with a support for holding a substrate with the object to be ground, an engine that can change the rotation speed, and a grinding plate that can adhere a grinding pad (grinding cloth).

[0075] As the abrasive pad, general nonwoven fabrics, polyurethane, and porous fluoropolymers can be used without particular restrictions. It is preferable to perform a troughing process on the abrasive pad to collect the abrasive fluid.

[0076] Regarding grinding conditions, for example, the preferred grinding speed of the grinding plate is 10 rpm (0.17 s). -1 ) or higher and 500rpm (8.33s) -1 The pressure applied to the substrate having the object to be polished (polishing pressure) is preferably 0.5 psi (3.4 kPa) or more and 10 psi (68.9 kPa) or less. There are no particular limitations on the method of supplying the polishing composition to the polishing pad; for example, a continuous supply method using a pump or the like can be used. There are no limitations on the amount supplied, but it is preferable that the surface of the polishing pad is always covered by the polishing composition of the present invention.

[0077] After grinding, the substrate is washed in running water, and the water droplets adhering to the substrate are removed and dried using a rotary dryer, thereby obtaining a substrate with a metal layer.

[0078] The grinding composition of the present invention can be a single-component type or a multi-component type, represented by a two-component type. Furthermore, the grinding composition of the present invention can be prepared by diluting the stock solution of the grinding composition to, for example, 10 times or more using a diluent such as water.

[0079] The embodiments of the present invention have been described in detail, but they are exemplary and not intended to be limiting. The scope of protection of the present invention should obviously be interpreted by the appended claims.

[0080] The present invention includes the following schemes and methods.

[0081] [1] A grinding composition for grinding an object having a layer containing more than 40% by mass of group 13 elements.

[0082] The grinding composition comprises cationic modified silica, polyalkylene glycol, and acid.

[0083] [2] The grinding composition according to [1], wherein the average primary particle size of the aforementioned cationic modified silica is 5 nm or more and 30 nm or less.

[0084] [3] According to the grinding composition of [2], the ratio of the average secondary particle size of the aforementioned cationic modified silica to the aforementioned average primary particle size of the aforementioned cationic modified silica (average secondary particle size / average primary particle size) is 1.2 or more and 3 or less.

[0085] [4] The grinding composition according to any one of [1] to [3], wherein the zeta potential of the aforementioned cationic modified silica in the aforementioned grinding composition is 5 mV or more and 60 mV or less.

[0086] [5] The grinding composition according to any one of [1] to [4], wherein the aforementioned polyalkylene glycol is polyethylene glycol.

[0087] [6] The grinding composition according to any one of [1] to [5], wherein the weight average molecular weight of the aforementioned polyalkylene glycol is 100 or more and 30,000 or less.

[0088] [7] The grinding composition according to any one of [1] to [6], wherein the aforementioned acid is at least one selected from the group consisting of acids having a nitrate group and acids having a sulfonic acid group.

[0089] [8] The grinding composition according to any one of [1] to [7] has a pH of 1 or higher and less than 6.

[0090] [9] A grinding method comprising the following steps: grinding an object having a layer having a content of more than 40% by mass of a group 13 element using the grinding composition described in any one of [1] to [8].

[0091]

[10] A method for manufacturing a semiconductor substrate, comprising: grinding a semiconductor substrate having a layer having a content of more than 40% by mass of a group 13 element by the grinding method described in [9].

[0092] Example

[0093] The present invention will be further described in detail using the following examples and comparative examples. However, the scope of protection of the present invention is not limited to the following examples. It should be noted that, unless otherwise specified, "%" and "parts" refer to "mass %" and "parts by mass," respectively.

[0094] <Average primary particle size of abrasive grains>

[0095] The average primary particle size of the abrasive grains was calculated from the specific surface area of ​​the silica particles based on the BET method and the density of the abrasive grains, measured using a Micromeritics "Flow Sorb II 2300".

[0096] <Average secondary particle size of abrasive grains>

[0097] The average secondary particle size of the abrasive particles was measured by a dynamic light scattering particle size / particle size distribution device UPA-UTI151 (manufactured by Nikkiso Corporation) in the form of volume average particle size (arithmetic mean particle size based on volume; Mv).

[0098] <Average cohesion of abrasive grains>

[0099] The average degree of association of abrasive grains is calculated by dividing the average secondary grain size of the abrasive grains by the average primary grain size of the abrasive grains.

[0100] <Zeta potential of abrasive particles>

[0101] The Zeta potential of the abrasive grains in the grinding composition was calculated as follows: The grinding composition was supplied to Malvern Panalytical Ltd. to manufacture Zetasizer Nano, and the measurement was performed using laser Doppler method (electrophoretic light scattering method) at a measurement temperature of 25°C. The obtained data was analyzed using the Smoluchowski formula to calculate the potential.

[0102] <Weight-average molecular weight of polyalkylene glycols>

[0103] The weight-average molecular weight of polyalkylene glycols was determined by gel permeation chromatography (GPC) using polyethylene glycol as a standard. Detailed conditions are as follows:

[0104] GPC device: manufactured by Shimadzu Corporation

[0105] Model: Prominence+ ELSD detector (ELSD-LTII)

[0106] Column: VP-ODS (manufactured by Shimadzu Corporation)

[0107] Mobile phase A: MeOH

[0108] B: 1% aqueous solution of acetic acid

[0109] Flow rate: 1 mL / min

[0110] Detector: ELSD temp. 40℃, Gain 8, N2GAS 350kPa

[0111] Column oven temperature: 40℃

[0112] Injection volume: 40 μl.

[0113] <pH of the grinding composition>

[0114] Regarding the pH of the grinding composition, a glass electrode hydrogen ion concentration indicator (Horiba Manufacturing Co., Ltd., model: F-23) was used. 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), and carbonate pH buffer pH: 10.01 (25°C)), the glass electrode was placed in the grinding composition, and the value after stabilization for more than 2 minutes was taken as the pH value.

[0115] [Preparation of Grinding Composition]

[0116] (Example 1)

[0117] Similar to the method described in Example 1 of Japanese Patent Application Publication No. 2005-162533, 1 L of a methanol solution of silica gel (silica concentration = 20% by mass) was used with γ-aminopropyltriethoxysilane (APTES) as a silane coupling agent at a concentration of 2 mmol (2 mM) 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.

[0118] At room temperature (25°C), the above-obtained cationic modified colloidal silica, which serves as abrasive particles, is added to pure water, which serves as a dispersion medium, at a final concentration of 4% by mass, and polyethylene glycol (PEG, manufactured by Fujifilm and Kojun Pharmaceutical Co., Ltd., weight average molecular weight: 200), which serves as a polyalkylene glycol, is added to a final concentration of 0.05% by mass, to obtain a mixture.

[0119] Then, nitric acid, as an acid, was added to the mixture at a final concentration of 0.0252% by mass, and the mixture was stirred at room temperature (25°C) for 30 minutes to prepare a grinding composition.

[0120] The resulting grinding composition has a pH of 2.5. Furthermore, the Zeta potential of the cationic modified colloidal silica in the obtained grinding composition was measured using the above method, and the result was +27 mV. Moreover, the particle size of the cationic modified colloidal silica in the grinding composition is the same as that of the cationic modified colloidal silica used.

[0121] (Examples 2-21, Comparative Examples 1-4)

[0122] The grinding composition was prepared in the same manner as in Example 1, except that the particle size and shape of the abrasive grains, the amount of APTES, the content of the abrasive grains, the type and content of the polyalkylene glycol, and the type and content of the acid were changed as shown in Table 1 below.

[0123] In Table 1 below, the symbol "-" indicates that the reagent is not used. Comparative Examples 1 and 2 are examples that use unmodified colloidal silica and do not use polyalkylene glycols. Comparative Example 4 is an example that does not use polyalkylene glycols.

[0124] The composition of each grinding composition is shown in Table 1 below.

[0125] [Table 1]

[0126]

[0127] [evaluate]

[0128] Using the various abrasive compositions prepared above, the surface of the object to be abraded is ground under the following conditions. As the object to be abraded, a thick layer is prepared on its surface. Boron (B)-silicon (Si) film (50% by mass of boron (B): 50% by mass of silicon (Si)) on silicon wafers (300 mm, blank wafer; manufactured by Advantec Co., Ltd.), with a thick layer of film. Silicon wafers (300 mm, blank wafers; manufactured by Advantec Co., Ltd.) with SiN (silicon nitride) films and those with thick... Silicon wafers with TiN (titanium nitride) films (300 mm, blank wafer; manufactured by Advanced Materials Technology Co., Ltd.):

[0129] (Grinding apparatus and grinding conditions)

[0130] Grinding device: FREX300E 300mm CMP single-sided grinding device manufactured by Ebara Manufacturing Co., Ltd.

[0131] Abrasive pad: Fujibo Holdings, Inc. manufactures nonwoven pads H800.

[0132] Grinding pressure: 3.0 psi (1 psi = 6894.76 Pa)

[0133] Grinding plate speed: 90 rpm

[0134] Carrier rotation speed: 91 rpm

[0135] Supply of grinding composition: overflow

[0136] Grinding composition supply rate: 250 ml / min

[0137] Grinding time: 60 seconds.

[0138] (Grinding speed)

[0139] For B-Si and SiN films, the thickness before and after grinding was determined using an optical film thickness gauge (ASET-f5x: KLA Tencor). For TiN films, the thickness before and after grinding was determined using a thin-film resistance gauge (VR-120: Kokusai Electric Semiconductor Service Inc.). Based on the determined thickness, the grinding speed of each object was calculated by dividing [(thickness before grinding) - (thickness after grinding)] by the grinding time.

[0140] (Grinding speed selection ratio)

[0141] Calculate the selection ratio of the grinding speed using the following formulas:

[0142] Grinding speed of B-Si / SiN = B-Si / SiN grinding speed

[0143] Grinding speed of B-Si / TiN = B-Si / TiN grinding speed

[0144] The evaluation results are shown in Table 2 below.

[0145] [Table 2]

[0146] Table 2

[0147]

[0148] As clearly shown in Table 2 above, the polishing composition of the embodiments improves the polishing speed of the B-Si film compared to the polishing composition of the comparative examples. Furthermore, it is evident that the polishing composition of the embodiments has a higher polishing speed ratio (selectivity ratio) of the B-Si film relative to the polishing speeds of other materials compared to the polishing composition of the comparative examples.

[0149] 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.

Claims

1. A grinding composition for grinding an object having a layer containing at least 40% by mass of Group 13 elements. The grinding composition comprises cationic modified silica, polyalkylene glycol, and acid. The pH of the grinding composition is below 3. The zeta potential of the cationic modified silica is above 5mV and below 60mV.

2. The grinding composition according to claim 1, wherein, The cationic modified silica is formed by immobilizing an amino-containing silane coupling agent or a quaternary ammonium-containing silane coupling agent on the surface of silica.

3. The grinding composition according to claim 1 or 2, wherein, The average primary particle size of the cationic modified silica is greater than 5 nm and less than 30 nm.

4. The grinding composition according to claim 3, wherein, The ratio of the average secondary particle size of the cationic modified silica to the average primary particle size of the cationic modified silica, i.e., the ratio of average secondary particle size to average primary particle size, is greater than 1.2 and less than 3.

5. The grinding composition according to claim 1 or 2, wherein, The polyalkylene glycol is polyethylene glycol.

6. The grinding composition according to claim 1 or 2, wherein, The weight-average molecular weight of the polyalkylene glycol is above 100 and below 30,000.

7. The grinding composition according to claim 1 or 2, wherein, The acid is selected from at least one acid selected from the group consisting of acids having a nitrate group and acids having a sulfonic acid group.

8. The grinding composition according to claim 1 or 2, wherein, The dispersion medium consists of water only.

9. The grinding composition according to claim 1 or 2, wherein, The weight-average molecular weight of the polyalkylene glycol is above 150 and below 350.

10. The grinding composition according to claim 7, wherein, The acid has a sulfonic acid group.

11. A grinding method comprising the following steps: grinding an object having a layer containing at least 40% by mass of a group 13 element using the grinding composition according to any one of claims 1 to 10.

12. A method for manufacturing a semiconductor substrate, comprising: grinding a semiconductor substrate having a layer having a content of 40% by mass or more of a group 13 element by the grinding method described in claim 11.

Images