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

Abstract

To provide an abrasive composition with excellent storage stability that can exhibit stable polishing performance even over extended storage periods. [Solution] An abrasive composition comprising abrasive grains and polyalkylene glycol, wherein the mass ratio of the content of polyalkylene glycol in the abrasive composition to the content of abrasive grains in the abrasive composition (content of polyalkylene glycol / content of abrasive grains) is greater than 0.25.

Description

Technical Field

[0001] The present invention relates to a polishing composition, a polishing method, and a method for manufacturing a semiconductor substrate.

Background Art

[0002] In recent years, with the multilayer wiring of the semiconductor substrate surface, when manufacturing a device, a so-called Chemical Mechanical Polishing (CMP) technique for polishing and planarizing a semiconductor substrate has been used. CMP is a method of planarizing the surface of an object to be polished (workpiece), such as a semiconductor substrate, using a polishing composition (slurry) containing abrasive grains such as silica, alumina, and ceria, a corrosion inhibitor, a surfactant, etc. The object to be polished (workpiece) is made of silicon, polysilicon, silicon oxide film (silicon oxide), silicon nitride, wiring made of metal, etc., plugs, etc.

[0003] For example, Patent Document 1 discloses a polishing composition used for polishing an object to be polished having a layer with a content of a Group 13 element of 40% by mass or more, the polishing composition containing cation-modified silica, a polyalkylene glycol, and an acid.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the polishing composition described in Patent Document 1 tends to have a decrease in polishing performance when the storage period becomes long, and there is room for improvement in terms of storage stability.

[0006] Therefore, the present invention aims to provide an abrasive composition that exhibits stable polishing performance even over extended storage periods and has excellent storage stability. [Means for solving the problem]

[0007] To solve the above problems, the inventors diligently conducted research. As a result, they found that the above problems can be solved by an abrasive composition containing abrasive grains and polyalkylene glycol, wherein the mass ratio of the polyalkylene glycol content in the abrasive composition to the abrasive grain content (polyalkylene glycol content / abrasive grain content) is greater than 0.25, and thus completed the present invention. [Effects of the Invention]

[0008] The present invention provides an abrasive composition that exhibits stable polishing performance even after extended storage periods, and has excellent storage stability. [Modes for carrying out the invention]

[0009] The present invention relates to an abrasive composition comprising abrasive grains and polyalkylene glycol, wherein the mass ratio of the content of polyalkylene glycol in the abrasive composition to the content of abrasive grains in the abrasive composition (content of polyalkylene glycol / content of abrasive grains) is greater than 0.25. An abrasive composition according to one embodiment of the present invention having such a configuration has excellent storage stability, which allows it to exhibit stable abrasive performance even after a long storage period.

[0010] The exact reason why the polishing composition of the present invention produces the above-mentioned effects is unknown, but it is thought to be due to the following mechanism. However, this mechanism is speculative, and the technical scope of the present invention is not limited by this mechanism.

[0011] The polyalkylene glycol contained in the polishing composition of the present invention functions as a polishing speed inhibitor, adsorbing onto the object to be polished (e.g., silicon dioxide) and suppressing the polishing speed of the object. However, when the polishing composition is stored for a long period of time, the polyalkylene glycol is adsorbed onto the abrasive particles contained in the polishing composition, and the amount of polyalkylene glycol adsorbed onto the object to be polished decreases. As a result, it is thought that the suppression of the polishing speed of the object to be polished becomes insufficient.

[0012] On the other hand, the polishing composition of the present invention has a mass ratio of polyalkylene glycol content to abrasive grain content (polyalkylene glycol content / abrasive grain content) of more than 0.25. As a result, even when the polishing composition is stored for a long period of time, a large amount of polyalkylene glycol is adsorbed onto the object to be polished, and the effect of suppressing the polishing speed of the object to be polished can be maintained, that is, it is thought that it can have excellent storage stability.

[0013] The embodiments of the present invention will be described below. However, the present invention is not limited to the embodiments described below.

[0014] In this specification, unless otherwise specified, operations and measurements of physical properties shall be performed under conditions of room temperature (20°C to 25°C) and relative humidity of 40% RH to 50% RH.

[0015] In this specification, "X or greater and Y or less" is used to mean that the numerical values ​​(X and Y) described before and after it are included as the lower and upper limits. When "X or greater and Y or less" is described multiple times, for example, "X1 or greater and Y1 or less, or X2 or greater and Y2 or less," the disclosure of each numerical value as the upper limit, the disclosure of each numerical value as the lower limit, and all combinations of those upper and lower limits are disclosed (i.e., they provide a lawful basis for correction). Specifically, corrections to X1 or greater, corrections to Y2 or less, corrections to X1 or less, corrections to Y2 or greater, corrections to X1 or greater and X2 or less, corrections to X1 or greater and Y2 or less, etc., must all be considered lawful.

[0016] The content (concentration) described herein may be the concentration at the point of use (POU), or the concentration before dilution to the POU concentration. Furthermore, all embodiments and combinations of descriptions disclosed herein should be understood as being disclosed in this application; that is, they should be understood as grounds for amendment.

[0017] [Abrasive grains] The abrasive particles contained in the polishing composition according to the present invention have the effect of mechanically polishing the object to be polished, and improve the polishing speed of the object to be polished by the polishing composition. Examples of abrasive particles include inorganic particles, organic particles, and organic-inorganic composite particles. Specific examples of inorganic particles include oxide particles such as silica particles, alumina particles, cerium oxide particles, chromium oxide particles, titanium dioxide particles, zirconium oxide particles, magnesium oxide particles, manganese dioxide particles, zinc oxide particles, and red iron oxide particles; nitride particles such as silicon nitride particles and boron nitride particles; carbide particles such as silicon carbide particles and boron carbide particles; diamond particles; and carbonates such as calcium carbonate and barium carbonate. Specific examples of organic particles include polymethyl methacrylate (PMMA) particles and poly(meth)acrylic acid particles (where (meth)acrylic acid comprehensively refers to acrylic acid and methacrylic acid), and polyacrylonitrile particles. Such abrasive particles may be used individually or in combination of two or more types. Furthermore, the abrasive grains may be synthetic or commercially available. In addition, the abrasive grains may be surface-modified.

[0018] The abrasive grains described herein are preferably inorganic particles, and among these, particles made of metal or metalloid oxides are preferred, with silica particles being particularly preferred. The technology disclosed herein can preferably be carried out, for example, in a manner in which the abrasive grains consist substantially of silica particles. Here, "substantially" means that 95% by mass or more (preferably 98% by mass or more, more preferably 99% by mass or more, and may be 100% by mass) of the particles constituting the abrasive grain are silica particles.

[0019] Specific examples of silica particles include colloidal silica, fumed silica, and precipitated silica. Silica particles may be used individually or in combination of two or more types. The use of colloidal silica is particularly preferred because it easily yields a polished surface with excellent surface quality after polishing.

[0020] Furthermore, the abrasive grains may be surface-modified. Specifically, the silica particles may have cationic groups. That is, the silica particles may be cation-modified silica or cation-modified colloidal silica. As a cation-modified colloidal silica, colloidal silica in which amino groups are immobilized on the surface is preferred.

[0021] Silica particles may have anionic groups. That is, silica particles may be anionically modified silica or anionically modified colloidal silica. As colloidal silica having anionic groups (anionically modified colloidal silica), colloidal silica in which anionic groups such as carboxylic acid groups, sulfonic acid groups, phosphonic acid groups, and aluminic acid groups are immobilized on the surface is preferred. There are no particular limitations on the method for producing such colloidal silica having anionic groups, and one example is a method of reacting colloidal silica with a silane coupling agent having anionic groups at its terminals.

[0022] From the viewpoint of further demonstrating the effects of the present invention, the abrasive grains contained in the polishing composition according to the present invention preferably have a positive zeta potential in the polishing composition, and more preferably are cation-modified silica having a positive zeta potential. The zeta potential of the abrasive grains in the polishing composition is not particularly limited, but is preferably greater than 0 mV, may be 5 mV or more, may be 10 mV or more, may be 20 mV or more, or may be 30 mV or more. Furthermore, the zeta potential of the abrasive grains (especially cation-modified silica) in the polishing composition is not particularly limited, but may be, for example, 100 mV or less, may be 80 mV or less, or may be 50 mV or less. The zeta potential of the abrasive grains in the polishing composition can be measured by the method described in the examples.

[0023] The zeta potential of abrasive grains (especially cation-modified silica) can be adjusted, for example, by the type and amount of the compound used for modifying the particles (especially silica particles), the amount of cationic groups, and the pH of the polishing composition, etc. However, the method for adjusting the zeta potential of the abrasive grains is not limited to these.

[0024] Hereinafter, cation-modified silica, which is a more preferable abrasive grain, will be described.

[0025] <Cation-modified silica> The polishing composition according to the present invention preferably contains cation-modified silica (silica having cationic groups) as abrasive grains. The cation-modified silica may be used alone or in combination of two or more. Also, commercially available products or synthetic products may be used as the cation-modified silica.

[0026] As the cation-modified silica, cation-modified colloidal silica (colloidal silica having cationic groups) is preferable.

[0027] Examples of the method for producing colloidal silica include the sodium silicate method and the sol-gel method. Colloidal silica produced by any production method can be suitably used as the abrasive grains according to the present invention. However, from the viewpoint of reducing metal impurities, colloidal silica produced by the sol-gel method is preferable. Colloidal silica produced by the sol-gel method is preferable because it has a low content of metal impurities diffusible in the semiconductor and corrosive ions such as chloride ions. The production of colloidal silica by the sol-gel method can be carried out using a conventionally known technique. Specifically, a hydrolyzable silicon compound (for example, alkoxysilane or its derivative) is used as a raw material, and a hydrolysis-condensation reaction is carried out to obtain colloidal silica. <00001​​Here, cationic modification refers to a state in which a cationic group (e.g., an amino group or a quaternary ammonium group) is bonded to the surface of silica (preferably colloidal silica). In a preferred embodiment of the present invention, the cationic modified silica is an amino group modified silica particle, and more preferably an amino group modified colloidal silica particle. According to such an embodiment, the above effects can be further improved.

[0029] To cationically modify silica (colloidal silica), a silane coupling agent having a cationic group (for example, an amino group or a quaternary ammonium group) is added to the silica (colloidal silica), and the reaction is carried out at a predetermined temperature for a predetermined time. In a preferred embodiment of the present invention, the cationically modified silica is obtained by immobilizing a silane coupling agent having an amino group or a silane coupling agent having a quaternary ammonium group on the surface of silica (more preferably colloidal silica).

[0030] Examples of silane coupling agents used in this case include those described in Japanese Patent Publication No. 2005-162533. Specifically, examples of silane coupling agents include N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltriethoxysilane, γ-aminopropyltriethoxysilane (3-aminopropyltriethoxysilane), γ-aminopropyltrimethoxysilane, γ-triethoxysilyl-N-(α,γ-dimethylbutylidene)propylamine, N-phenyl-γ-aminopropyltrimethoxysilane, hydrochloride of N-(vinylbenzyl)-β-aminoethyl-γ-aminopropyltriethoxysilane, octadecyldimethyl-(γ-trimethoxysilylpropyl)-ammonium chloride, and N-trimethoxysilylpropyl-N,N,N-trimethylammonium chloride. In particular, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltriethoxysilane, γ-aminopropyltriethoxysilane, and γ-aminopropyltrimethoxysilane are preferred due to their good reactivity with colloidal silica. The silane coupling agent may be used alone or in combination of two or more types.

[0031] The silane coupling agent can be added to silica (colloidal silica) either as is or diluted with a hydrophilic organic solvent or pure water. Dilution with a hydrophilic organic solvent or pure water can suppress the formation of aggregates. When diluting the silane coupling agent with a hydrophilic organic solvent or pure water, it should be diluted so that the concentration of the silane coupling agent is preferably 0.01 g to 1 g, more preferably 0.1 g to 0.7 g, per liter of the hydrophilic organic solvent or pure water. The hydrophilic organic solvent is not particularly limited, but examples include lower alcohols such as methanol, ethanol, isopropanol, and butanol.

[0032] Furthermore, the amount of cationic groups introduced to the surface of silica (colloidal silica) can be adjusted by controlling the amount of silane coupling agent added. The amount of silane coupling agent used is not particularly limited, but is preferably 0.1 mM to 5 mM, more preferably 0.5 mM to 3 mM, relative to the reaction solution. Note that 1 mM = 1 mmol / L.

[0033] The processing temperature when cationically modifying silica (colloidal silica) with a silane coupling agent is not particularly limited and can be in the range from room temperature (e.g., 25°C) to approximately the boiling point of the dispersion medium in which the silica (colloidal silica) is dispersed. Specifically, it is 0°C to 100°C, preferably room temperature (e.g., 25°C) to about 90°C.

[0034] The shape of cation-modified silica is not particularly limited and may be spherical or non-spherical. Specific examples of non-spherical shapes include polygonal prisms such as triangular or square prisms, cylindrical shapes, cylindrical shapes with a bulge in the center, donut shapes with a hole in the center, plate shapes, so-called cocoon shapes with a constriction in the center, so-called aggregate spherical shapes where multiple particles are integrated, so-called konpeito shapes with multiple protrusions on the surface, rugby ball shapes, and many other shapes, and are not particularly limited.

[0035] The average primary particle diameter of the cation-modified silica 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 diameter of the cation-modified silica increases, the polishing speed of the workpiece improves. Furthermore, the average primary particle diameter of the cation-modified silica 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 diameter of the cation-modified silica decreases, the surface condition of the workpiece after polishing may improve.

[0036] In other words, the average primary particle diameter of cation-modified silica is preferably 1 nm to 100 nm, more preferably 3 nm to 50 nm, and even more preferably 5 nm to 30 nm. The average primary particle diameter of cation-modified silica can be calculated, for example, based on the specific surface area (SA) of cation-modified silica calculated by the BET method and the density of cation-modified silica. The average primary particle diameter of cation-modified silica will be the value measured by the method described in the examples.

[0037] Furthermore, the average secondary particle diameter of the cation-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 diameter of the cation-modified silica increases, the resistance during polishing decreases, enabling stable polishing. Furthermore, the average secondary particle diameter of the cation-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 diameter of the cation-modified silica decreases, the surface area per unit mass of the cation-modified silica increases, the frequency of contact with the object to be polished improves, and the polishing speed improves further. That is, the average secondary particle diameter of the cation-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. Note that the average secondary particle diameter of the cation-modified silica is the value measured by the method described in the examples.

[0038] The ratio of the average secondary particle diameter to the average primary particle diameter of cation-modified silica (average secondary particle diameter / average primary particle diameter, hereinafter also referred to as "average degree of association") is preferably greater than 1.0, more preferably 1.1 or greater, and even more preferably 1.2 or greater. Furthermore, the average degree of association of cation-modified silica is preferably 4 or less, more preferably 3.5 or less, and even more preferably 3 or less. In other words, the average degree of association of cation-modified silica is preferably greater than 1.0 and 4 or less, more preferably 1.1 or more and 3.5 or less, and even more preferably 1.2 or more and 3 or less.

[0039] The average degree of association of cation-modified silica can be obtained by dividing the average secondary particle diameter of the cation-modified silica by the average primary particle diameter.

[0040] The upper limit of the aspect ratio of cation-modified silica 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. Within this range, defects on the surface of the object to be polished can be further reduced. The aspect ratio is the average of the values ​​obtained by taking the smallest rectangle that circumscribes the image of cation-modified silica particles using a scanning electron microscope and dividing the length of the longer side of that rectangle by the length of the shorter side of the same rectangle, and can be determined using general image analysis software. The lower limit of the aspect ratio of cation-modified silica in the polishing composition is not particularly limited, but it is preferably 1.0 or more.

[0041] In the particle size distribution of cation-modified silica determined by laser diffraction scattering, the lower limit of D90 / D50, which is the ratio of the particle diameter (D90) when the cumulative particle weight from the fine particles reaches 90% of the total particle weight to the particle diameter (D50) when the cumulative particle weight from the fine particles 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 cation-modified silica in the polishing composition determined by laser diffraction scattering, the upper limit of the ratio D90 / D50, which is the ratio of the particle diameter (D90) when the cumulative particle weight from the fine particles reaches 90% of the total particle weight to the particle diameter (D50) when the cumulative particle weight from the fine particles 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. Within this range, defects on the surface of the object to be polished can be further reduced.

[0042] The size of cation-modified silica (average primary particle diameter, average secondary particle diameter, aspect ratio, D90 / D50, etc.) can be appropriately controlled by selecting the appropriate manufacturing method for cation-modified silica.

[0043] The lower limit of the zeta potential of the cation-modified silica in the polishing composition is preferably 5 mV or higher, more preferably 10 mV or higher, and even more preferably 15 mV or higher. The upper limit of the zeta potential of the cation-modified silica in the polishing composition is preferably 70 mV or lower, more preferably 60 mV or lower, and even more preferably 50 mV or lower. In other words, the zeta potential of the cation-modified silica in the polishing composition is preferably 5 mV to 70 mV, more preferably 10 mV to 60 mV, and even more preferably 15 mV to 50 mV.

[0044] As described above, in this specification, the zeta potential of cation-modified silica is the value measured by the method described in the examples. Furthermore, as described above, the zeta potential of cation-modified silica can be adjusted by the type and amount of compound used to modify the silica particles, the amount of cationic groups, and the pH of the polishing composition.

[0045] The content (concentration) of abrasive grains (especially cation-modified silica) in the polishing composition is not particularly limited, but is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and even more preferably 0.5% by mass or more, based on 100% by mass of the total mass of the polishing composition. Furthermore, the content (concentration) of abrasive grains (especially cation-modified silica) in the polishing composition is not particularly limited, but is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less, based on 100% by mass of the total mass of the polishing composition.

[0046] In other words, the content (concentration) of abrasive grains (particularly cation-modified silica) in the polishing composition is preferably 0.1% by mass or more and 30% by mass or less, more preferably 0.3% by mass or more and 20% by mass or less, and even more preferably 0.5% by mass or more and 10% by mass or less, based on 100% by mass of the total mass of the polishing composition.

[0047] In the case of an abrasive composition used as a polishing liquid for polishing an object (i.e., an abrasive composition in POU), the lower limit of the content (concentration) of abrasive particles (especially cation-modified silica) in the abrasive composition is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, even more preferably 0.5% by mass or more, and particularly preferably 0.6% by mass or more, based on 100% by mass of the total mass of the abrasive composition. Furthermore, the upper limit of the content (concentration) of abrasive particles in the abrasive composition is preferably 15% by mass or less, more preferably 10% by mass or less, even more preferably 8% by mass or less, and particularly preferably 5% by mass or less, based on 100% by mass of the total mass of the abrasive composition.

[0048] In other words, in the case of an abrasive composition used as a polishing liquid to polish an object, the content (concentration) of abrasive particles (especially cation-modified silica) is preferably 0.1% to 15% by mass, more preferably 0.3% to 10% by mass, even more preferably 0.5% to 8% by mass, and particularly preferably 0.6% to 5% by mass, based on 100% by mass of the total mass of the abrasive composition.

[0049] Furthermore, in the case of a polishing composition used after dilution for polishing (i.e., the concentrated liquid before dilution into the polishing composition in POU), the content (concentration) of abrasive particles (particularly cation-modified silica) is usually appropriate to be 30% by mass or less, and more preferably 25% by mass or less, from the viewpoint of storage stability and filterability. Also, from the viewpoint of taking advantage of the benefits of a concentrated liquid, the content (concentration) of abrasive particles (particularly cation-modified silica) in the polishing composition used after dilution for polishing (i.e., the concentrated liquid before dilution into the polishing composition in POU) is preferably more than 1% by mass, and more preferably 3% by mass or more.

[0050] In other words, the content (concentration) of abrasive particles (particularly cation-modified silica) in the polishing composition used for polishing after dilution (i.e., the concentrated liquid before dilution in the polishing composition in POU) is preferably more than 1% by mass and 30% by mass or less, and more preferably 3% by mass or more and 25% by mass or less.

[0051] If the content (concentration) of abrasive grains (especially cation-modified silica) is within this range, an abrasive composition with excellent storage stability can be obtained, which can exhibit stable polishing performance even over long storage periods. Note that if the abrasive composition contains two or more types of abrasive grains, the content (concentration) of abrasive grains refers to the total amount of these grains.

[0052] [Polyalkylene glycol] The polishing composition according to the present invention contains polyalkylene glycol. Polyalkylene glycol has the effect of suppressing the polishing rate of the object to be polished (particularly silicon dioxide). Polyalkylene glycol may be used alone or in combination of two or more types. Furthermore, commercially available polyalkylene glycol may be used or a synthetic product may be used.

[0053] The type of polyalkylene glycol is not particularly limited, but examples include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyethylene glycol-polypropylene glycol random copolymer, polyethylene glycol-polytetramethylene glycol random copolymer, polypropylene glycol-polytetramethylene glycol random copolymer, polyethylene glycol-polypropylene glycol-polytetramethylene glycol random copolymer, polyethylene glycol-polypropylene glycol-polytetramethylene glycol random copolymer, polyethylene glycol-polypropylene glycol block copolymer, polypropylene glycol-polypropylene glycol-polypropylene glycol triblock copolymer, polyethylene glycol-polypropylene glycol-polypropylene glycol triblock copolymer, etc. Among these, polyethylene glycol and polypropylene glycol are preferred, and polypropylene glycol is more preferred.

[0054] 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. In other words, the weight-average molecular weight (Mw) of the polyalkylene glycol is preferably 100 to 30,000, more preferably 150 to 10,000, and even more preferably 200 to 1,000.

[0055] In this specification, the weight-average molecular weight of polyalkylene glycol can be measured by gel permeation chromatography (GPC) using polyethylene glycol as the standard substance. The detailed measurement method is as described in the examples.

[0056] The content (concentration) of polyalkylene glycol in the polishing composition is not particularly limited, but is preferably 0.3% by mass or more, more preferably 0.4% by mass or more, and even more preferably 0.5% by mass or more, based on 100% by mass of the total mass of the polishing composition. Furthermore, although the content (concentration) of polyalkylene glycol in the polishing composition is not particularly limited, is preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less, based on 100% by mass of the total mass of the polishing composition.

[0057] In other words, the content (concentration) of polyalkylene glycol in the polishing composition is preferably 0.3% by mass or more and 30% by mass or less, more preferably 0.4% by mass or more and 25% by mass or less, and even more preferably 0.5% by mass or more and 20% by mass or less, based on 100% by mass of the total mass of the polishing composition.

[0058] In the case of an abrasive composition used as a polishing liquid for polishing an object (i.e., an abrasive composition in POU), the lower limit of the polyalkylene glycol content (concentration) in the abrasive composition is preferably 0.3% by mass or more, more preferably 0.35% by mass or more, even more preferably 0.4% by mass or more, and particularly preferably 0.5% by mass or more, based on 100% by mass of the total mass of the abrasive composition. Furthermore, the upper limit of the polyalkylene glycol content (concentration) in an abrasive composition used as a polishing liquid for polishing an object (i.e., an abrasive composition in POU) is preferably 15% by mass or less, more preferably 10% by mass or less, even more preferably 5% by mass or less, and particularly preferably 3% by mass or less, based on 100% by mass of the total mass of the abrasive composition.

[0059] In other words, in the case of an abrasive composition used as a polishing liquid to polish an object, the abrasive content (concentration) is preferably 0.3% to 15% by mass, more preferably 0.35% to 10% by mass, even more preferably 0.4% to 5% by mass, and particularly preferably 0.5% to 3% by mass, based on 100% by mass of the total mass of the abrasive composition.

[0060] Furthermore, in the case of a polishing composition used for polishing after dilution (i.e., the concentrated solution before dilution in the polishing composition in POU), the polyalkylene glycol content (concentration) is usually appropriate to be 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less, from the viewpoint of storage stability, filterability, and improvement of the polishing speed of titanium nitride. Also, from the viewpoint of taking advantage of the benefits of a concentrated solution, the abrasive grain content (concentration) is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 3% by mass or more.

[0061] In other words, in the case of an abrasive composition used for polishing after dilution (i.e., the concentrated liquid before dilution in the abrasive composition in POU), the abrasive content (concentration) is preferably 1% by mass or more and 30% by mass or less, and may be 2% by mass or more and 30% by mass or less, 3% by mass or more and 30% by mass or less, 2% by mass or more and 25% by mass or less, 2% by mass or more and 20% by mass or less, 3% by mass or more and 25% by mass or less, or 3% by mass or more and 20% by mass or less.

[0062] If the polyalkylene glycol content (concentration) is within this range, an abrasive composition with excellent storage stability can be obtained, which can exhibit stable polishing performance even over long storage periods. Note that if the abrasive composition contains two or more types of polyalkylene glycol, the polyalkylene glycol content (concentration) refers to the total amount of these polyalkylene glycols.

[0063] [Mass ratio of abrasive content to polyalkylene glycol content] In one embodiment of the present invention, the mass ratio of the polyalkylene glycol content in the polishing composition to the abrasive grain content (polyalkylene glycol content / abrasive grain content) is greater than 0.25. If this mass ratio is 0.25 or less, the storage stability of the polishing composition decreases (the effect of suppressing the polishing speed of the object to be polished decreases).

[0064] The mass ratio is preferably 0.3 or higher, more preferably 0.35 or higher, even more preferably 0.4 or higher, and particularly preferably 0.5 or higher. Furthermore, the mass ratio is preferably 8.0 or lower, more preferably 6.0 or lower, even more preferably 5.0 or lower, and particularly preferably 3.0 or lower.

[0065] In other words, the mass ratio of the polyalkylene glycol content in the polishing composition to the abrasive grain content (polyalkylene glycol content / abrasive grain content) is preferably 0.3 to 8.0, more preferably 0.35 to 6.0, even more preferably 0.4 to 5.0, and particularly preferably 0.5 to 3.0.

[0066] [pH] The pH of the polishing composition according to the present invention is preferably 1.0 or higher, more preferably 1.5 or higher, and even more preferably 2.0 or higher. Furthermore, the pH is preferably less than 7.0, more preferably 6.0 or lower, even more preferably less than 5.0, and particularly preferably 4.5 or lower. In other words, the pH of the polishing composition according to the present invention is preferably 1.0 or higher and less than 7.0, more preferably 1.5 or higher and 6.0 or lower, even more preferably 2.0 or higher and 5.0 or lower, and particularly preferably 2.0 or higher and 4.5 or lower.

[0067] The pH of the polishing composition can be obtained by using a pH meter (for example, a glass electrode type hydrogen ion concentration indicator (model number: F-23) manufactured by Horiba, Ltd.), performing a three-point calibration using standard buffers (phthalate pH buffer pH: 4.01 (25°C), neutral phosphate pH buffer pH: 6.86 (25°C), carbonate pH buffer pH: 10.01 (25°C)), then placing the glass electrode in the polishing composition and measuring the value after it has stabilized for at least two minutes.

[0068] The polishing composition according to the present invention may contain a pH adjusting agent for adjusting the pH. The pH adjusting agent may be either an acid or a base, and may be either an inorganic compound or an organic compound. The pH adjusting agent may be used alone or in a mixture of two or more.

[0069] Specific examples of acids that can be used as pH adjusters include inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, boric acid, carbonic acid, hypophosphorous acid, phosphorous acid, and phosphoric acid; and organic acids such as formic acid, acetic acid, propionic acid, butyric acid, valeric acid, 2-methylbutyric acid, n-hexanoic acid, 3,3-dimethylbutyric acid, 2-ethylbutyric acid, 4-methylpentanoic acid, n-heptanoic acid, 2-methylhexanoic acid, n-octanoic acid, 2-ethylhexanoic acid, benzoic acid, glycolic acid, salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid, phthalic acid, malic acid, tartaric acid, citric acid, lactic acid, diglycolic acid, 2-furanic acid, 2,5-franic acid, 3-furanic acid, 2-tetrahydrofuranic acid, methoxyacetic acid, methoxyphenylacetic acid, and phenoxyacetic acid.

[0070] Specific examples of bases that can be used as pH adjusters include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, hydroxides of group 2 elements, and inorganic bases such as ammonia; amines such as aliphatic amines and aromatic amines, and organic bases such as quaternary ammonium hydroxides.

[0071] The amount of pH adjuster added is not particularly limited and should be adjusted as appropriate so that the polishing composition reaches the desired pH.

[0072] [Dispersion medium] The polishing composition according to the present invention preferably contains a dispersion medium for dispersing each component. Examples of dispersion media include water; alcohols such as methanol, ethanol, and ethylene glycol; ketones such as acetone; and mixtures thereof. Of 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 consists substantially of water. The term "substantially" above means that a dispersion medium other than water may be included insofar as the effects of the present invention can be achieved. More specifically, the dispersion medium preferably consists of 90% to 100% by mass of water and 0% to 10% by mass of a dispersion medium other than water, and more preferably consists of 99% to 100% by mass of water and 0% to 1% by mass of a dispersion medium other than water. Most preferably, the dispersion medium is water.

[0073] From the viewpoint of not inhibiting the action of the components contained in the polishing composition, the dispersion medium should preferably be water that contains as few impurities as possible. Specifically, pure water, ultrapure water, or distilled water is more preferable, which is obtained by removing impurity ions with an ion exchange resin and then removing foreign matter by passing it through a filter.

[0074] [Electrical conductivity of abrasive compositions] The electrical conductivity (EC) of the polishing composition according to the present invention is not particularly limited. In the case of a polishing composition used as is as a polishing liquid for polishing an object (i.e., a polishing composition in POU), the electrical conductivity of the polishing composition is preferably 0.1 mS / cm or more and 10 mS / cm or less, and more preferably 0.3 mS / cm or more and 5 mS / cm or less. In the case of a polishing composition used after dilution for polishing (i.e., a concentrated liquid before dilution into a polishing composition in POU), the electrical conductivity is preferably 0.5 mS / cm or more and 20 mS / cm or less, and more preferably 1.0 mS / cm or more and 10 mS / cm or less.

[0075] If the electrical conductivity of the polishing composition is within this range, the polishing speed of the object to be polished (e.g., silicon nitride) can be maintained at a high level. Furthermore, the repulsion between abrasive grains can be appropriately adjusted to ensure stability. The electrical conductivity of the polishing composition can be adjusted by the type and amount of pH adjusting agent, etc. The electrical conductivity of the polishing composition can be measured by the method described in the examples.

[0076] [Other ingredients] The polishing composition according to the present invention may further contain known additives that can be used in polishing compositions, such as complexing agents, preservatives, fungicides, oxidizing agents, and water-soluble polymers other than polyalkylene glycol, to the extent that they do not impair the effects of the present invention. The polishing composition according to the present invention is preferably acidic. For this reason, it is more preferable that the polishing composition contains a fungicide. That is, in one embodiment of the present invention, the polishing composition is substantially composed of abrasive grains, polyalkylene glycol, a dispersion medium, a fungicide, and at least one of a pH adjuster and an oxidizing agent. In one embodiment of the present invention, the polishing composition is substantially composed of abrasive grains, polyalkylene glycol, a dispersion medium, a fungicide, a pH adjuster, and an oxidizing agent. Here, "the polishing composition is substantially composed of abrasive grains, polyalkylene glycol, a dispersion medium, a fungicide, and at least one of a pH adjuster and an oxidizing agent" means that the total content of abrasive grains, polyalkylene glycol, a dispersion medium, a pH adjuster, a fungicide, and an oxidizing agent exceeds 99% by mass (upper limit: 100% by mass) of the total mass of the polishing composition. Preferably, the polishing composition consists of abrasive grains, polyalkylene glycol, a dispersion medium, an antifungal agent, a pH adjuster, and an oxidizing agent (total content of the above = 100% by mass).

[0077] Examples of antifungal agents (preservatives) that can be added to the polishing composition according to the present invention include isothiazoline-based preservatives such as 1,2-benzoisothiazole-3(2H)-one (BIT), 2-methyl-4-isothiazolin-3-one, and 5-chloro-2-methyl-4-isothiazolin-3-one; parahydroxybenzoic acid esters; phenoxyethanol; and the like. These antifungal agents may be used individually or in combination of two or more.

[0078] Examples of oxidizing agents that can be added to the polishing composition according to the present invention include hydrogen peroxide, sodium peroxide, barium peroxide, nitric acid, iron nitrate, aluminum nitrate, ammonium nitrate, peroxomonosulfate, ammonium peroxomonosulfate, metal peroxomonosulfate, peroxodisulfate, ammonium peroxodisulfate, metal peroxodisulfate, peroxolinic acid, peroxosulfate, sodium peroxoborate, performic acid, peracetic acid, perbenzoic acid, perphthalic acid, hypobromous acid, hypoiodic acid, chloric acid, bromic acid, iodic acid, periodic acid, perchloric acid, hypochlorous acid, sodium hypochlorite, calcium hypochlorite, potassium permanganate, metal chromate, metal dichromate, iron chloride, iron sulfate, iron citrate, iron ammonium sulfate, and the like. These oxidizing agents may be used individually or in combination of two or more.

[0079] [Method for producing abrasive compositions] The method for producing the polishing composition according to the present invention is not particularly limited and can be obtained, for example, by stirring and mixing abrasive grains, polyalkylene glycol, and other additives as needed in a dispersion medium (e.g., water). Details of each component are as described above.

[0080] The temperature at which each component is mixed is not particularly limited, but it is preferably between 10°C and 40°C, and heating may be used to increase the dissolution rate. The mixing time is also not particularly limited as long as uniform mixing is achieved.

[0081] [Object to be polished] The polishing composition according to one embodiment of the present invention is not particularly limited and can be applied to known objects to be polished used in the field of CMP (Chemical Polishing). For this reason, the form of the object to be polished is not particularly limited, but a plate-shaped layer is preferred, a substrate containing the layer is more preferred, and a semiconductor substrate is even more preferred. Examples include a substrate composed of a single layer, or a substrate containing the layer to be polished and other layers (e.g., a support layer or other functional layers). Examples of materials constituting the object to be polished are not particularly limited, but include, for example, silicon-containing materials, metal-containing materials (e.g., elemental metals, metal oxides, metal nitrides, etc.). The materials constituting the object to be polished may be a single material or a combination of two or more materials.

[0082] Examples of silicon-containing materials are not particularly limited, but include, for example, materials having silicon-oxygen bonds, materials having silicon-silicon bonds, materials having silicon-nitrogen bonds, and materials containing group 13 elements and silicon. Examples of materials having silicon-oxygen bonds are not particularly limited, but include, for example, silicon oxide, BD (black diamond: SiOCH), FSG (fluorosilicate glass), HSQ (hydrogen silsesquioxane), CYCLOTENE, SiLK, MSQ (methyl silsesquioxane), etc. Examples of polishing objects having silicon-silicon bonds are not particularly limited, but include, for example, polycrystalline silicon (polysilicon, Poly-Si), amorphous silicon, single-crystal silicon, n-type doped single-crystal silicon, p-type doped single-crystal silicon, Si-based alloys such as SiGe, etc. Examples of materials having silicon-nitrogen bonds are not particularly limited, but include, for example, silicon nitride, silicon carbonitride (SiCN), etc. Examples of materials containing Group 13 elements and silicon include boron(B)-silicon(Si) alloys.

[0083] Among these silicon-containing materials, materials having silicon-oxygen bonds are preferred, and silicon dioxide is more preferred. While there are no particular limitations on the silicon dioxide-containing film, examples include TEOS (Tetraethyl Orthosilicate) type silicon dioxide films (also referred to as "TEOS" or "TEOS film" in this specification) produced using tetraethyl orthosilicate as a precursor, 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. A TEOS film is even more preferred as the silicon dioxide.

[0084] Among the metal-containing materials, the elemental metals are not particularly limited, but examples include tungsten, copper, cobalt, hafnium, nickel, gold, silver, platinum, palladium, rhodium, ruthenium, iridium, osmium, aluminum, nickel, titanium, and alloys thereof. The metal oxides are not particularly limited, but examples include alumina. The metal nitrides are not particularly limited, but examples include titanium nitride and tantalum nitride. Among these, metal nitrides are preferred, and titanium nitride is more preferred.

[0085] [Polishing method and method for manufacturing semiconductor substrates] As described above, the polishing composition according to the present invention is suitably used for polishing objects containing silicon dioxide. Therefore, the present invention provides a polishing method for polishing an object containing silicon dioxide with the polishing composition according to the present invention. The present invention also provides a method for manufacturing a semiconductor substrate, comprising polishing a semiconductor substrate containing silicon dioxide by the above polishing method.

[0086] As a polishing apparatus, a general polishing apparatus can be used that has a holder for holding a substrate or the like with the object to be polished, a motor with adjustable rotation speed, and a polishing platen to which a polishing pad (abrasive cloth) can be attached.

[0087] As the polishing pad, general nonwoven fabrics, polyurethanes, and porous fluororesins can be used without any particular restrictions. Preferably, the polishing pad has grooves that allow the polishing liquid to accumulate.

[0088] Regarding polishing conditions, for example, the rotation speed of the polishing platen is 10 rpm (0.17 s). -1 ) or more 500rpm (8.33s -1 ) is preferred. The pressure applied to the substrate having the object to be polished (polishing pressure) is preferably 0.5 psi (3.4 kPa) to 10 psi (68.9 kPa). The method of supplying the polishing composition to the polishing pad is not particularly limited, and for example, a method of continuously supplying it with a pump or the like can be employed. There is no limit to the amount supplied, but it is preferable that the surface of the polishing pad is always covered with the polishing composition according to the present invention.

[0089] After polishing is complete, the substrate is washed with running water, and any water droplets adhering to the substrate are removed using a spin dryer or the like to dry it, thereby obtaining a substrate having a layer containing metal.

[0090] The polishing composition according to the present invention may be a one-component type or a multi-component type, including a two-component type. Furthermore, the polishing composition according to the present invention may be prepared by diluting the stock solution of the polishing composition with a diluent such as water, for example, 2 to 10 times.

[0091] [Polishing speed] The polishing method according to the present invention can polish an object containing silicon dioxide at a specific polishing speed. The polishing method according to the present invention can be preferably applied to polishing an object containing silicon dioxide.

[0092] The upper limit of the silicon dioxide polishing rate is preferably 45 Å / min or less, more preferably 40 Å / min or less, even more preferably 35 Å / min or less, and particularly preferably 30 Å / min or less. By keeping the polishing rate at 40 Å / min or less, the polishing rate of silicon dioxide is sufficiently suppressed. Furthermore, when polishing an object containing silicon dioxide and titanium nitride, the polishing selectivity of titanium nitride over silicon dioxide can be improved. Note that 1 Å = 0.1 nm.

[0093] Furthermore, when the object to be polished contains titanium nitride, the lower limit of the titanium nitride polishing speed is preferably 300 Å / min or higher, more preferably 400 Å / min or higher, even more preferably 450 Å / min or higher, and particularly preferably 600 Å / min or higher. Polishing at a speed of 300 Å / min or higher allows for favorable polishing of the titanium nitride. There is no particular upper limit to the polishing speed of the titanium nitride film, but in practice, it is 8000 Å / min or lower.

[0094] When the object to be polished contains silicon oxide and silicon nitride, the selectivity ratio of the polishing rate of titanium nitride to the polishing rate of silicon oxide (polishing rate of titanium nitride / polishing rate of silicon oxide) is preferably greater than 15, preferably 20 or more, and more preferably 25 or more.

[0095] While embodiments of the present invention have been described in detail, these are descriptive and illustrative, and not limiting, and it is clear that the scope of the present invention should be interpreted by the appended claims.

[0096] The present invention encompasses the following embodiments and forms. [1] comprising abrasive grains and polyalkylene glycol, An abrasive composition in which the mass ratio of the content of polyalkylene glycol in the abrasive composition to the content of abrasive grains in the abrasive composition (content of polyalkylene glycol / content of abrasive grains) is greater than 0.25: [2] The abrasive grains are the polishing composition described in [1] above, having a positive zeta potential: [3] The abrasive composition according to [1] or [2] above, wherein the abrasive grain is cation-modified silica: [4] The polishing composition according to any one of [1] to [3] above, wherein the polyalkylene glycol is polypropylene glycol: [5] The abrasive composition according to any one of [1] to [4] above, wherein the mass ratio (content of polyalkylene glycol / content of abrasive grains) is 0.5 or more: [6] The abrasive composition according to any one of [1] to [5] above, wherein the mass ratio (content of polyalkylene glycol / content of abrasive grains) is 8.0 or less: [7] The abrasive composition according to any one of [1] to [6] above, wherein the content of the polyalkylene glycol is 0.3% by mass or more and 30% by mass or less, based on 100% by mass of the total mass of the abrasive composition: [8] A polishing composition according to any one of [1] to [7] above, further comprising a dispersion medium: [9] Abrasive composition according to any of [1] to [8] above, having a pH of 2.0 or higher and 4.5 or lower:

[10] Polishing compositions according to any one of [1] to [9] above, used for polishing objects containing silicon dioxide:

[11] A polishing method comprising polishing an object to be polished containing silicon dioxide using any of the polishing compositions described in [1] to

[10] above:

[12] A method for manufacturing a semiconductor substrate, comprising the step of polishing a semiconductor substrate containing silicon dioxide by the polishing method described in

[11] above. [Examples]

[0097] The present invention will be described in more detail using the following examples and comparative examples. However, the technical scope of the present invention is not limited to the following examples. Unless otherwise specified, "%" and "parts" mean "mass%" and "parts by mass," respectively.

[0098] <Average primary particle size of abrasive grains> The average primary particle size of the abrasive grains was calculated from the specific surface area of ​​silica particles measured by the BET method using a "Flow Sorb II 2300" manufactured by Micromerities, and the density of the abrasive grains.

[0099] <Average secondary particle size of abrasive grains> The average secondary particle diameter of the abrasive grains was measured as the volume-average particle diameter (volume-based arithmetic mean diameter; Mv) using a dynamic light scattering particle size and particle size distribution analyzer UPA-UT151 (manufactured by Nikkiso Co., Ltd.).

[0100] <Zeta potential of abrasive grains> The zeta potential of abrasive grains in the polishing composition was calculated by subjecting the polishing composition to a Malvern Panalytical Zetasizer Nano and measuring it using laser Doppler (electrophoretic light scattering measurement) at a measurement temperature of 25°C. The obtained data was then analyzed using the Smoluchowski equation.

[0101] <Weight-average molecular weight of polyalkylene glycols> The weight-average molecular weight of polyalkylene glycols was measured by gel permeation chromatography (GPC) using polyethylene glycol as the standard. The detailed conditions are as follows: GPC equipment: Manufactured by Shimadzu Corporation Model: Prominence + ELSD detector (ELSD-LTII) Column: VP-ODS (manufactured by Shimadzu Corporation) Mobile phase A:MeOH B: 1% aqueous solution of acetic acid Flow rate: 1mL / min Detector: ELSD, temp. 40℃, Gain 8, N2GAS 350kPa Oven temperature: 40℃ Injection volume: 40μl.

[0102] <pH of the abrasive composition> The pH of the polishing composition was determined using a glass electrode type hydrogen ion concentration indicator (Horiba, Ltd., Model: F-23). ​​After three-point calibration using standard buffers (phthalate pH buffer pH: 4.01 (25°C), neutral phosphate pH buffer pH: 6.86 (25°C), carbonate pH buffer pH: 10.01 (25°C)), the glass electrode was placed in the polishing composition, and the pH value after stabilization for at least two minutes was taken as the pH value.

[0103] <Electrical conductivity of abrasive compositions> The electrical conductivity (EC) of the polishing composition was measured using a benchtop electrical conductivity meter (manufactured by Horiba, Ltd., model number: DS-71 LAQUA®).

[0104] [Preparation of abrasive compositions] (Manufacturing Example 1) In the same manner as described in Example 1 of Japanese Patent Publication No. 2005-162533, γ-aminopropyltriethoxysilane (referred to as "APTES" in the table below) was used at a concentration of 0.025% by mass (1.13 mM) as a silane coupling agent in 1 L of an aqueous dispersion of silica sol (silica concentration = 20% by mass) to prepare cocoon-shaped cation-modified colloidal silica with an average primary particle diameter of 25.0 nm, an average secondary particle diameter of 50.0 nm, an average degree of association of 2.0, and an aspect ratio of 1.2.

[0105] The cation-modified colloidal silica obtained above was added to pure water, the dispersion medium, at room temperature (25°C) to a final content of 5.4% by mass. Furthermore, 2-methyl-4-isothiazolin-3-one (manufactured by THE DOW CHEMICAL COMPANY, referred to as "MIT" in the table below) was added as an antifungal agent to a final content of 0.0009% by mass (0.078 mM) to obtain a mixed solution.

[0106] Subsequently, polypropylene glycol (Mw:200, manufactured by Sanyo Chemical Industries, Ltd.) (referred to as "PPG200" in the table below) was added as a polyalkylene glycol to a final content of 3.0% by mass, and nitric acid was added as a pH adjuster to a final content of 0.065% by mass. The mixture was stirred and mixed at room temperature (25°C) for 30 minutes to obtain polishing composition 1. The mass ratio of the polypropylene glycol content to the abrasive content in polishing composition 1 (polypropylene glycol content / abrasive content, shown as "polyalkylene glycol / abrasive mass ratio" in the table below) was 0.56.

[0107] (Example 1-1) The polishing composition 1 obtained in the above manufacturing example 1 was stored for 7 days in a constant temperature bath (manufactured by Yamato Scientific Co., Ltd., product number: DK600) set to a temperature of 25°C. Immediately after storage, the pH of polishing composition 1 was 2.19 and the electrical conductivity (EC) was 2.93 mS / cm.

[0108] Subsequently, the composition was diluted six times with water, and a 31% by mass aqueous solution of hydrogen peroxide (manufactured by Santoku Chemical Industry Co., Ltd.) was added so that the final content of hydrogen peroxide, the oxidizing agent, was 0.093% by mass, to obtain polishing composition 1-1.

[0109] The obtained polishing composition 1-1 had a pH of 2.98, an electrical conductivity (EC) of 0.517 mS / cm, and a zeta potential of cation-modified colloidal silica in polishing composition 1-1 of +34 mV. Furthermore, the particle size of cation-modified colloidal silica in polishing composition 1-1 was similar to that of the cation-modified colloidal silica used. In addition, the mass ratio of the polypropylene glycol content to the abrasive content in polishing composition 1-1 (polypropylene glycol content / abrasive content) was 0.56.

[0110] (Examples 1-2) The polishing composition 1 obtained in the above manufacturing example 1 was stored for 7 days in a constant temperature bath set at 80°C. Immediately after storage, the pH of polishing composition 1 was 2.18 and the electrical conductivity (EC) was 2.95 mS / cm.

[0111] Subsequently, the composition was diluted six times with water, and a 31% by mass aqueous solution of hydrogen peroxide (manufactured by Santoku Chemical Industry Co., Ltd.) was added so that the final content of hydrogen peroxide, the oxidizing agent, was 0.093% by mass, to obtain polishing composition 1-2.

[0112] The obtained polishing composition 1-2 had a pH of 2.97, an electrical conductivity (EC) of 0.547 mS / cm, and a zeta potential of cation-modified colloidal silica in polishing composition 1-2 of +29 mV. Furthermore, the particle size of the cation-modified colloidal silica in polishing composition 1-2 was similar to that of the cation-modified colloidal silica used. In addition, the mass ratio of the polypropylene glycol content to the abrasive content in polishing composition 1-2 (polypropylene glycol content / abrasive content) was 0.56.

[0113] Furthermore, if the storage conditions of 7 days at 80°C are converted to storage conditions of 25°C, the storage period becomes 317 days (the same applies to Examples 2-2, 3-2, and Comparative Example 1-2 below).

[0114] (Manufacturing example 2) Polishing composition 2 was obtained in the same manner as in Production Example 1, except that the amount of polypropylene glycol (PPG200) added was changed so that the final content was 12.0% by mass. The mass ratio of the polypropylene glycol content to the abrasive content in polishing composition 2 (polyalkylene glycol content / abrasive content) was 2.22.

[0115] (Example 2-1) The polishing composition 2 obtained in the above manufacturing example 2 was stored for 7 days in a constant temperature bath set at a temperature of 25°C. Immediately after storage, the pH of polishing composition 2 was 2.18 and the electrical conductivity (EC) was 2.30 mS / cm.

[0116] Subsequently, the composition was diluted six times with water, and a 31% by mass aqueous solution of hydrogen peroxide (manufactured by Santoku Chemical Industry Co., Ltd.) was added so that the final content of hydrogen peroxide, the oxidizing agent, was 0.093% by mass, to obtain polishing composition 2-1.

[0117] The obtained polishing composition 2-1 had a pH of 2.99, an electrical conductivity (EC) of 0.538 mS / cm, and a zeta potential of cation-modified colloidal silica in polishing composition 2-1 of +37 mV. Furthermore, the particle size of cation-modified colloidal silica in polishing composition 2-1 was similar to that of the cation-modified colloidal silica used. In addition, the mass ratio of the polypropylene glycol content to the abrasive content in polishing composition 2-1 (polypropylene glycol content / abrasive content) was 2.22.

[0118] (Example 2-2) The polishing composition 2 obtained in the above manufacturing example 2 was stored for 7 days in a constant temperature bath set at 80°C. Immediately after storage, the pH of polishing composition 2 was 2.17 and the electrical conductivity (EC) was 2.33 mS / cm.

[0119] Subsequently, the composition was diluted six times with water, and a 31% by mass aqueous solution of hydrogen peroxide (manufactured by Santoku Chemical Industry Co., Ltd.) was added so that the final content of hydrogen peroxide, the oxidizing agent, was 0.093% by mass, to obtain polishing composition 2-2.

[0120] The obtained polishing composition 2-2 had a pH of 2.96, an electrical conductivity (EC) of 0.532 mS / cm, and a zeta potential of cation-modified colloidal silica in polishing composition 2-2 of +28 mV. Furthermore, the particle size of the cation-modified colloidal silica in polishing composition 2-2 was similar to that of the cation-modified colloidal silica used. In addition, the mass ratio of the polypropylene glycol content to the abrasive content in polishing composition 2-2 (polypropylene glycol content / abrasive content) was 2.22.

[0121] (Manufacturing Example 3) Polishing composition 3 was obtained in the same manner as in Production Example 1, except that the amount of polypropylene glycol (PPG200) added was changed so that the final content was 30.0% by mass. The mass ratio of the polypropylene glycol content to the abrasive grain content in polishing composition 3 (polypropylene glycol content / abrasive grain content) was 5.56.

[0122] (Example 3-1) The polishing composition 3 obtained in the above manufacturing example 3 was stored for 7 days in a constant temperature bath set at a temperature of 25°C. Immediately after storage, the pH of the polishing composition 3 was 2.18 and the electrical conductivity (EC) was 2.30 mS / cm.

[0123] Subsequently, the composition was diluted six times with water, and a 31% by mass aqueous solution of hydrogen peroxide (manufactured by Santoku Chemical Industry Co., Ltd.) was added so that the final content of hydrogen peroxide, the oxidizing agent, was 0.093% by mass, to obtain polishing composition 3-1.

[0124] The obtained polishing composition 3-1 had a pH of 2.98, an electrical conductivity (EC) of 0.527 mS / cm, and a zeta potential of cation-modified colloidal silica in polishing composition 3-1 of +33 mV. Furthermore, the particle size of cation-modified colloidal silica in polishing composition 3-1 was similar to that of the cation-modified colloidal silica used. In addition, the mass ratio of the polypropylene glycol content to the abrasive content in polishing composition 3-1 (polypropylene glycol content / abrasive content) was 5.56.

[0125] (Example 3-2) The polishing composition 3 obtained in the above manufacturing example 3 was stored for 7 days in a constant temperature bath set at 80°C. Immediately after storage, the pH of the polishing composition 3 was 2.17 and the electrical conductivity (EC) was 2.33 mS / cm.

[0126] Subsequently, the composition was diluted six times with water, and a 31% by mass aqueous solution of hydrogen peroxide (manufactured by Santoku Chemical Industry Co., Ltd.) was added so that the final content of hydrogen peroxide, the oxidizing agent, was 0.093% by mass, to obtain polishing composition 3-2.

[0127] The obtained polishing composition 3-2 had a pH of 2.95, an electrical conductivity (EC) of 0.545 mS / cm, and a zeta potential of +27 mV for the cation-modified colloidal silica in polishing composition 3-2. Furthermore, the particle size of the cation-modified colloidal silica in polishing composition 3-2 was similar to that of the cation-modified colloidal silica used. In addition, the mass ratio of the polypropylene glycol content to the abrasive content in polishing composition 3-2 (polypropylene glycol content / abrasive content) was 5.56.

[0128] (Comparative manufacturing example 1) Abrasive composition comparison 1 was obtained in the same manner as in manufacturing example 1, except that the amount of polypropylene glycol (PPG200) added was changed so that the final content was 0.06% by mass. The mass ratio of the polypropylene glycol content to the abrasive grain content in abrasive composition comparison 1 (polypropylene glycol content / abrasive grain content) was 0.011.

[0129] (Comparative Example 1-1) The polishing composition Comparative 1 obtained in the above comparative manufacturing example 1 was stored for 7 days in a constant temperature bath set at a temperature of 25°C. Immediately after storage, the pH of polishing composition Comparative 1 was 2.18 and the electrical conductivity (EC) was 2.30 mS / cm.

[0130] Subsequently, the composition was diluted six times with water, and a 31% by mass aqueous solution of hydrogen peroxide (manufactured by Santoku Chemical Industry Co., Ltd.) was added so that the final content of hydrogen peroxide, the oxidizing agent, was 0.093% by mass, to obtain comparative polishing composition 1-1.

[0131] The pH of the obtained polishing composition Comparison 1-1 was 2.98, the electrical conductivity (EC) was 0.517 mS / cm, and the zeta potential of the cation-modified colloidal silica in polishing composition Comparison 1-1 was +34 mV. Furthermore, the particle size of the cation-modified colloidal silica in polishing composition Comparison 1-1 was similar to that of the cation-modified colloidal silica used. In addition, the mass ratio of the polypropylene glycol content to the abrasive content in polishing composition Comparison 1-1 (polypropylene glycol content / abrasive content) was 0.011.

[0132] (Comparative Example 1-2) The polishing composition Comparative 1 obtained in the above comparative manufacturing example 1 was stored for 7 days in a constant temperature bath set at 80°C. Immediately after storage, the pH of polishing composition Comparative 1 was 2.17 and the electrical conductivity (EC) was 2.33 mS / cm.

[0133] Subsequently, the composition was diluted six times with water, and a 31% by mass aqueous solution of hydrogen peroxide (manufactured by Santoku Chemical Industry Co., Ltd.) was added so that the final content of hydrogen peroxide, the oxidizing agent, was 0.093% by mass, to obtain comparative polishing compositions 1-2.

[0134] The pH of the obtained polishing composition Comparison 1-2 was 2.97, the electrical conductivity (EC) was 0.547 mS / cm, and the zeta potential of the cation-modified colloidal silica in polishing composition Comparison 1-2 was +29 mV. Furthermore, the particle size of the cation-modified colloidal silica in polishing composition Comparison 1-2 was similar to that of the cation-modified colloidal silica used. In addition, the mass ratio of the polypropylene glycol content to the abrasive content in polishing composition Comparison 1-2 (polypropylene glycol content / abrasive content) was 0.011.

[0135] The compositions of polishing compositions 1-3 and comparative polishing composition 1 are shown in Table 1 below, and the compositions of polishing compositions 1-1 to 1-2, polishing compositions 2-1 to 2-2, polishing compositions 3-1 to 3-2, and comparative polishing compositions 1-1 to 1-2 are shown in Table 2 below.

[0136] [Table 1]

[0137] [Table 2]

[0138] <Evaluation of polishing speed of abrasive compositions> The surface of the object to be polished was polished under the following conditions using the polishing compositions listed in Table 2 above. The objects to be polished were a silicon wafer (300 mm, blanket wafer; manufactured by Advantec Co., Ltd.) with a 10,000 Å thick TEOS-type silicon oxide (SiO2) film (TEOS film) formed on its surface, and a silicon wafer (300 mm, blanket wafer; manufactured by Advance Materials Technology Co., Ltd.) with a 3,600 Å thick titanium nitride (TiN) film formed on its surface.

[0139] (Polishing equipment and polishing conditions) Polishing equipment: Polishing machine manufactured by Ebara Corporation (Model: FREX 300E) Polishing pad: Polyurethane pad IC1000 manufactured by Nitta DuPont Corporation Polishing pressure: 3.0 psi (1 psi = 6894.76 Pa) Polishing plate rotation speed: 113 rpm Supply of polishing composition: flow-through Polishing composition supply amount: 250ml / min Polishing time: 1 minute.

[0140] (Evaluation of polishing speed) For the TEOS film, the thickness before and after polishing was determined using an optical film thickness measuring instrument (ASET-f5x: manufactured by KLA-Tencor Co., Ltd.). For the titanium nitride film, the thickness before and after polishing was determined using a sheet resistance measuring instrument (VR120 / 08SD: manufactured by Kokusai Electric Semiconductor Service Co., Ltd.) which is based on the DC four-probe method. From the determined thickness, the polishing speed for each object was calculated by dividing [(thickness before polishing) - (thickness after polishing)] by the polishing time.

[0141] The evaluation results for polishing speed are shown in Table 3 below. In Table 3, the TEOS film is indicated by "SiO2" and the titanium nitride film by "TiN". For the TEOS film, the rate of change (polishing speed change rate) was calculated based on the following formula, comparing the polishing speed measured after storing the polishing composition at 80°C for 7 days with the polishing speed measured after storing the polishing composition at 25°C for 7 days. A smaller value for the polishing speed change rate indicates better storage stability.

[0142]

number

[0143] Furthermore, the selectivity ratio of the polishing rate of titanium nitride to that of silicon dioxide (indicated as "TiN / SiO2" in the table) was also calculated and is shown in Table 3 below.

[0144] [Table 3]

[0145] As is clear from Table 3 above, the polishing composition of the example was found to have a smaller rate of change in polishing speed compared to the polishing composition of the comparative example, i.e., it had superior storage stability. Furthermore, the polishing composition of the example was found to have a higher titanium nitride polishing speed and a higher selectivity ratio of the titanium nitride polishing speed to the silicon oxide polishing speed compared to the polishing composition of the comparative example.

Claims

1. It contains abrasive particles and polyalkylene glycol, An abrasive composition in which the mass ratio of the content of polyalkylene glycol in the abrasive composition to the content of abrasive grains in the abrasive composition (content of polyalkylene glycol / content of abrasive grains) is greater than 0.

25.

2. The polishing composition according to claim 1, wherein the abrasive grains have a positive zeta potential.

3. The polishing composition according to claim 2, wherein the abrasive grains are cation-modified silica.

4. The polishing composition according to claim 1, wherein the polyalkylene glycol is polypropylene glycol.

5. The polishing composition according to claim 1, wherein the mass ratio (content of polyalkylene glycol / content of abrasive grains) is 0.5 or more.

6. The polishing composition according to claim 1, wherein the mass ratio (content of polyalkylene glycol / content of abrasive particles) is 8.0 or less.

7. The polishing composition according to claim 1, wherein the content of the polyalkylene glycol is 0.3% by mass or more and 30% by mass or less, based on 100% by mass of the total mass of the polishing composition.

8. The polishing composition according to claim 1, further comprising a dispersion medium.

9. The polishing composition according to claim 1, wherein the pH is 2.0 or higher and 4.5 or lower.

10. A polishing composition according to any one of claims 1 to 9, used for polishing an object to be polished that contains silicon dioxide.

11. A polishing method comprising polishing an object to be polished containing silicon dioxide using the polishing composition described in any one of claims 1 to 9.

12. A method for manufacturing a semiconductor substrate, comprising the step of polishing a semiconductor substrate containing silicon dioxide by the polishing method described in claim 11.

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