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

Abstract

The present invention provides a means for reducing surface defects in a substrate after the polishing of the substrate. The present invention relates to a method for polishing a substrate, the method comprising a polishing step, in which the polishing step includes at least two polishing stages each for rotating a polishing plate while supplying a polishing composition to a contact surface between the substrate and a polishing pad attached to the polishing plate to polish the substrate, in which the at least two polishing stages include a polishing stage 1 for polishing on the polishing plate using a polishing composition S1 and a polishing stage 2 for polishing on the same polishing plate as that used in the polishing stage 1 using a polishing composition S2 subsequent to the polishing stage 1, the polishing composition S1 comprises abrasive grains 1, water, and a water-soluble polymer having an abrasive grain adsorption parameter of 5 or more, the polishing composition S2 comprises abrasive grains 2, water, and a water-soluble polymer having the abrasive grain adsorption parameter of less than 5, and the water-soluble polymer having the abrasive grain adsorption parameter of 5 or more is not contained in an amount of 0.005% by mass or more.

Description

[Technical Field]

[0001] The present invention relates to a polishing method, a method for producing a semiconductor substrate, and a polishing composition set. [Background technology]

[0002] The surfaces of semiconductor substrates such as silicon wafers and other substrates used as components of semiconductor products are generally finished to a high-quality mirror finish through a lapping process (rough polishing process) and a polishing process (precision polishing process). Chemical mechanical polishing (CMP) using a polishing slurry containing abrasive grains in a liquid is widely used as the polishing method in the polishing process. This polishing method relies on the combined action of mechanical polishing by the abrasive grains and chemical polishing by components other than the abrasive grains contained in the liquid, and is known to produce mirror surfaces with excellent smoothness and low defectivity.

[0003] Furthermore, in order to achieve higher integration and higher speeds for integrated circuits such as ULSI used in computers, design rules for semiconductor devices are becoming finer year by year. As a result, there are more and more cases where even smaller surface defects have a negative impact on the performance of semiconductor devices, and the importance of managing nano-order defects, which were not previously considered a problem, is increasing.

[0004] In recent years, semiconductor substrates such as silicon wafers and other substrates have come to require higher-quality surfaces, and various studies have been conducted on polishing compositions that can meet these requirements. As one such technique, Japanese Patent Application Laid-Open No. 2017-183478 discloses a method for polishing silicon wafers, which includes a finish polishing step, a pre-polishing step immediately preceding the finish polishing step, and a rinsing step between the finish polishing step and the pre-polishing step, in which the silicon wafer is rinsed after the pre-polishing step. In this method, the pre-polishing composition and rinsing agent are selected so that the hydrophilic parameter of the rinsing agent used to rinse the silicon wafer in the rinsing step is smaller than the hydrophilic parameter of the pre-polishing composition used in the pre-polishing step. This document also discloses that this method can reduce haze and microdefects on polished silicon wafers, thereby achieving a high-quality polished surface. Summary of the Invention

[0005] In recent years, there has been an increasing demand for reducing surface defects on semiconductor substrates such as silicon wafers and other substrates. In order to meet such demands, an object of the present invention is to provide a means capable of reducing surface defects on polished substrates.

[0006] The above-mentioned object of the present invention can be achieved by the following means: A method for polishing a substrate, comprising: The polishing method includes a polishing step, The polishing step includes two or more polishing stages in which the substrate is polished by rotating the polishing platen while supplying a polishing composition to a contact surface between the substrate and a polishing pad attached to the polishing platen, The two or more polishing stages include: a polishing stage 1 in which polishing is performed on a polishing platen using a polishing composition S1; After the polishing stage 1, a polishing stage 2 is performed using a polishing composition S2 on the same polishing table as the polishing stage 1; The polishing composition S1 contains abrasive grains 1, water, and a water-soluble polymer having an abrasive adsorption parameter of 5 or more calculated by the following procedures (1) to (4): The polishing composition S2 contains abrasive grains 2, water, and the water-soluble polymer having an abrasive adsorption parameter of less than 5, and does not contain the water-soluble polymer having an abrasive adsorption parameter of 5 or more in an amount of 0.005 mass% or more. Polishing method: (1) Prepare a test solution L containing 0.08% by mass of colloidal silica having an average primary particle size of 25 nm and an average secondary particle size of 50 nm, 0.004% by mass of a water-soluble polymer to be measured, and 0.005% by mass of ammonia, with the remainder being water. (2) The total organic carbon concentration (TOC value) of the test liquid L is measured, and the obtained TOC value is set as the total organic carbon concentration W0 of the water-soluble polymer to be measured contained in the test liquid L. (3) The test liquid L is centrifuged at a rotation speed of 26,000 rpm for 30 minutes to separate it into a sediment and a supernatant, and then the TOC value of the supernatant is measured, and the obtained TOC value is defined as the total organic carbon concentration W1 of the water-soluble polymer to be measured contained in the supernatant. (4) The adsorption ratio of the water-soluble polymer to be measured is calculated using the following formula, and this value is used as the abrasive adsorption parameter.

[0007]

number

[0008] The above object of the present invention can also be achieved by the following means: A polishing composition set for use in a method for polishing a substrate, comprising: The polishing method includes a polishing step, The polishing step includes two or more polishing stages in which the substrate is polished by rotating the polishing platen while supplying a polishing composition to a contact surface between the substrate and a polishing pad attached to the polishing platen, The two or more polishing stages include: a polishing stage 1 for polishing on a polishing table; A polishing stage 2 that polishes the substrate on the same polishing table as the polishing stage 1 after the polishing stage 1, The polishing composition set includes: a polishing composition S1 used in the polishing stage 1, which contains abrasive grains 1, water, and a water-soluble polymer having an abrasive grain adsorption parameter of 5 or more calculated by the following procedures (1) to (4); a polishing composition S2 used in the polishing stage 2, which contains abrasive grains 2, water, and a water-soluble polymer having an abrasive grain adsorption parameter of less than 5, and does not contain a water-soluble polymer having an abrasive grain adsorption parameter of 5 or more in an amount of 0.005 mass% or more; A polishing composition set comprising: (1) Prepare a test solution L containing 0.08% by mass of colloidal silica having an average primary particle size of 25 nm and an average secondary particle size of 50 nm, 0.004% by mass of a water-soluble polymer to be measured, and 0.005% by mass of ammonia, with the remainder being water. (2) The total organic carbon concentration (TOC value) of the test liquid L is measured, and the obtained TOC value is set as the total organic carbon concentration W0 of the water-soluble polymer to be measured contained in the test liquid L. (3) The test liquid L is centrifuged at 26,000 rpm for 30 minutes to separate it into a sediment and a supernatant, and then the TOC value of the supernatant is measured, and the obtained TOC value is defined as the total organic carbon concentration W1 of the water-soluble polymer to be measured contained in the supernatant. (4) The adsorption ratio of the water-soluble polymer to be measured is calculated using the following formula, and this value is used as the abrasive adsorption parameter.

[0009]

number

[0010] Hereinafter, embodiments of the present invention will be described. However, the present invention is not limited to the following embodiments. Furthermore, unless otherwise specified, operations and measurements of physical properties are performed at room temperature (20°C to 25°C) and a relative humidity of 40% RH to 50% RH.

[0011] In this specification, "(meth)acrylic acid" is a general term for acrylic acid and methacrylic acid. Similarly, other compounds containing (meth) are also general terms for compounds having "meth" in their names and compounds not having "meth."

[0012] <Polishing method> One aspect of the present invention is a method for polishing a substrate, comprising: The polishing method includes a polishing step, The polishing step includes two or more polishing stages in which the substrate is polished by rotating the polishing platen while supplying a polishing composition to a contact surface between the substrate and a polishing pad attached to the polishing platen, The two or more polishing stages include: a polishing stage 1 in which polishing is performed on a polishing platen using a polishing composition S1; After the polishing stage 1, a polishing stage 2 is performed using a polishing composition S2 on the same polishing table as the polishing stage 1; The polishing composition S1 contains abrasive grains 1, water, and a water-soluble polymer having an abrasive adsorption parameter of 5 or more calculated by the steps (1) to (4) described below; The polishing composition S2 contains abrasive grains 2, water, and a water-soluble polymer having an abrasive adsorption parameter of less than 5, and does not contain the water-soluble polymer having an abrasive adsorption parameter of 5 or more in an amount of 0.005 mass% or more (i.e., the concentration of the water-soluble polymer having an abrasive adsorption parameter of 5 or more in the polishing composition S2 is less than 0.005 mass% with respect to the total mass of the polishing composition S2). This aspect provides a means for reducing surface defects on a polished substrate.

[0013] The inventors speculate that the mechanism by which the above-mentioned problems can be solved by the present invention is as follows. Water-soluble polymers with a high abrasive adsorption parameter are prone to adsorption to silica and other materials. First, in polishing stage 1, a substrate is polished using a polishing composition containing a water-soluble polymer with a high abrasive adsorption parameter. During this process, the water-soluble polymer with a high abrasive adsorption parameter adsorbs to the abrasives and the substrate, protecting the substrate. As a result, in polishing stage 1, the substrate can be processed while suppressing damage to the substrate. Next, in polishing stage 2, the substrate is polished using a polishing composition containing a water-soluble polymer with a low abrasive adsorption parameter. During this process, the water-soluble polymer with a low abrasive adsorption parameter does not adsorb well to the abrasives and acts to remove abrasives remaining on the substrate. As a result, the substrate can be cleaned well in polishing stage 2. As a result, the substrate obtained after polishing using the polishing method of the present invention is less damaged and has fewer abrasives remaining on the substrate, resulting in significantly reduced surface defects. Note that the above mechanism is based on speculation, and its accuracy does not affect the technical scope of the present invention.

[0014] A method for polishing a substrate according to one embodiment of the present invention includes a polishing step, which includes two or more polishing stages in which the substrate is polished by rotating the polishing table while supplying a polishing composition to the contact surface between the substrate and a polishing pad attached to the polishing table, and the two or more polishing stages include polishing stage 1 in which polishing is performed on the polishing table using polishing composition S1, and polishing stage 2 in which, after polishing stage 1, polishing is performed on the same polishing table as polishing stage 1 using polishing composition S2.

[0015] [Polishing process] The polishing step included in the polishing method according to one embodiment of the present invention will be described below.

[0016] A polishing apparatus used in a polishing step according to one embodiment of the present invention and polishing conditions that can be employed in polishing stage 1 and polishing stage 2 will be described.

[0017] The polishing apparatus is not particularly limited, but for example, a general polishing apparatus can be used that is equipped with a holder for holding a substrate or the like having an object to be polished, a motor with an adjustable rotation speed, and a polishing platen to which a polishing pad (polishing cloth) can be attached. For example, a single-sided polishing apparatus or a double-sided polishing apparatus can be used. The commercially available polishing apparatus is not particularly limited, but an example of a single-sided polishing apparatus is a sheet-fed polishing machine, model "PNX 332B," manufactured by Okamoto Machine Tool Works, Ltd.

[0018] When polishing an object to be polished using a single-sided polishing device, the object to be polished is held using a holder called a template, and a polishing platen with a polishing pad (abrasive cloth) attached is pressed against one side of the object to be polished, and the polishing platen is rotated while a polishing composition is supplied, thereby polishing one side of the object to be polished.

[0019] When polishing an object using a double-sided polishing machine, the object is held using a holder called a carrier, and polishing plates with polishing pads (polishing cloths) attached are pressed against both sides of the object from both sides, and both sides of the object are polished by rotating the polishing plates on both sides while supplying a polishing composition.

[0020] By using such a polishing apparatus, a polishing composition is supplied to the contact surface between the substrate and the polishing pad attached to the polishing platen, and the substrate is polished by rotating the polishing platen.

[0021] Thus, the polishing in the polishing step may be either single-sided polishing or double-sided polishing, but single-sided polishing is preferred.

[0022] As the polishing pad, general nonwoven fabric type, polyurethane type, suede type, etc. can be used without any particular limitation. As the polishing pad, a polishing pad with grooves formed so that the polishing composition can be accumulated can also be used. There are no particular limitations on commercially available polishing pads, but examples of nonwoven fabric types include "FP55" manufactured by Fujibo Ehime Co., Ltd., and examples of suede types include "POLYPAS275NX" manufactured by Fujibo Ehime Co., Ltd.

[0023] The preferred range of polishing conditions varies depending on the purpose of polishing at each polishing stage. Therefore, the polishing conditions are not particularly limited, and appropriate conditions can be adopted depending on the purpose of polishing at each polishing stage.

[0024] Polishing is preferably carried out by rotating a platen (polishing table), and more preferably by moving (e.g., rotating) the substrate and the platen (polishing table) relative to each other. The rotation speed of the platen (polishing table) and the rotation speed of the head (carrier, template) are not particularly limited, but are preferably set independently at 10 rpm (0.17 s -1 ) or more 100rpm(1.67s -1 ) or less, and more preferably 20 rpm (0.33 s -1 ) or more than 60 rpm (1 s -1 ) or less, and more preferably 25 rpm (0.42 s -1 ) or more than 55 rpm (0.92 s -1 ) or less. Within these ranges, surface defects occurring on the polished surface of the substrate are further reduced, and production efficiency is further improved. Furthermore, the rotation speed of the platen (polishing table) and the rotation speed of the head (carrier, template) may be the same or different.

[0025] The substrate is usually pressed by a surface plate. The pressure (polishing load) at this time is not particularly limited, but is preferably 5 kPa or more and 30 kPa or less, more preferably 10 kPa or more and 25 kPa or less. Within this range, surface defects occurring on the polished surface of the substrate are further reduced, and production efficiency is further improved.

[0026] Each polishing composition may be in a concentrated form before being supplied to the object to be polished. The concentrated form is the form of a concentrated liquid of the polishing composition, which can also be understood as a stock solution of the polishing composition. Such concentrated polishing compositions are advantageous from the viewpoints of convenience and cost reduction during production, distribution, storage, etc. The concentration ratio is not particularly limited, and can be, for example, about 2 to 100 times in volume terms, and is usually about 5 to 50 times, for example, about 10 to 40 times. Such a concentrated liquid can be diluted at the desired time to prepare a polishing composition, and the polishing composition can be supplied to the object to be polished. Dilution can be performed, for example, by adding water to the concentrated liquid and mixing.

[0027] The supply speed of polishing composition is not particularly limited, because it can be appropriately selected according to the size of polishing platen, but it is preferable that the supply amount is such that the entire object to be polished is covered.In consideration of economic efficiency, the supply speed of polishing composition is more preferably 0.1L / min or more and 5L / min or less, and even more preferably 0.2L / min or more and 2L / min or less.In this range, the surface defects occurring on the polished surface of substrate can be further reduced, and production efficiency can be further improved.

[0028] The method for supplying the polishing composition is not particularly limited, and a method of continuously supplying the polishing composition using a pump or the like (flowing over) may be employed.

[0029] There are no particular restrictions on the temperature at which the polishing composition is maintained in the polishing apparatus, but from the standpoint of the stability of the polishing rate and the effect of reducing surface defects that occur on the polished surface of the substrate, it is preferably 15°C or higher and 40°C or lower, and more preferably 18°C ​​or higher and 25°C or lower.

[0030] In addition, the polishing composition may be recovered after being used to polish an object to be polished, and if necessary, various components that may be contained in the polishing composition may be added to adjust the composition, and then reused to polish an object to be polished.

[0031] In addition to polishing stage 1 and polishing stage 2, the polishing process may further include other polishing stages as necessary, and preferably further includes other polishing stages. In this case, the positions of polishing stage 1 and polishing stage 2 are not particularly limited, but polishing stage 1 is preferably the polishing stage immediately before polishing stage 2, and more preferably polishing stage 1 is the polishing stage immediately before the final polishing stage, and polishing stage 2 is the final polishing stage. The number of polishing stages included in the polishing process is preferably 2 to 10, and more preferably 3 to 6.

[0032] In polishing stage 1 and polishing stage 2, the substrate is polished on the same polishing platen. If the polishing process includes another polishing stage in addition to polishing stage 1 and polishing stage 2, in the other polishing stage, the substrate may be polished on the same polishing platen as polishing stages 1 and 2, or on a polishing platen different from polishing stages 1 and 2; however, in the other polishing stage, the substrate is preferably polished on a polishing platen different from polishing stages 1 and 2.

[0033] The polishing stages 1 and 2 may be polishing stages that perform any type of polishing. However, it is preferable that polishing stage 1 is a polishing stage that performs finish polishing, and polishing stage 2 is a polishing stage that performs rinse polishing. The polishing stage that performs finish polishing refers to a polishing stage that more finely polishes a substrate that has been roughly polished in a polishing stage that performs pre-polishing such as preliminary polishing. Furthermore, the polishing stage that performs rinse polishing refers to a polishing stage that is performed on a polishing table (platen) to which a polishing pad is attached, and removes residues from the surface of the polished object to be polished by the frictional force (physical action) of the polishing pad and the action of the polishing composition (rinse polishing composition). Therefore, polishing composition S2 is preferably a rinse polishing composition.

[0034] For these reasons, in a preferred embodiment of the present invention, the polishing process further includes polishing stage 1, polishing stage 2, and one or more other polishing stages arranged before polishing stage 1, and polishing stage 1 is the polishing stage immediately before the final polishing stage and is a polishing stage for performing finish polishing, and polishing stage 2 is the final polishing stage and is a polishing stage for performing rinse polishing.

[0035] The relationship between the polishing time in polishing stage 1 and the polishing time in polishing stage 2 is not particularly limited, but it is preferable that the polishing time in polishing stage 2 is shorter than the polishing time in polishing stage 1. In this case, surface defects occurring on the polished surface of the substrate are further reduced.

[0036] The polishing time in polishing stage 1 is not particularly limited, but is preferably more than 80 seconds, more preferably 100 seconds or more, and even more preferably 150 seconds or more. Within these ranges, surface defects on the polished surface of the substrate are further reduced. Furthermore, the polishing time in polishing stage 1 is not particularly limited, but is preferably 500 seconds or less, more preferably 300 seconds or less, and even more preferably 250 seconds or less. Within these ranges, production efficiency is improved.

[0037] The polishing time in polishing stage 2 is not particularly limited, but is preferably 1 second or more, more preferably 3 seconds or more, and even more preferably 5 seconds or more. Within these ranges, surface defects on the polished surface of the substrate are further reduced. Furthermore, the polishing time in polishing stage 2 is not particularly limited, but is preferably 80 seconds or less, more preferably 60 seconds or less, and even more preferably 40 seconds or less. Within these ranges, production efficiency is further improved.

[0038] The above polishing apparatus and polishing conditions are merely examples, and may be outside the above ranges, or the settings may be changed as appropriate.

[0039] [Other processes] The polishing method according to one embodiment of the present invention may further include other steps, such as a cleaning step.

[0040] The cleaning step may be performed before, during, or after the polishing step. However, it is preferable that the cleaning step is performed after the polishing step, in which the substrate is cleaned. The cleaning method in the cleaning step is not particularly limited, but a preferred example is a method in which a first cleaning tank containing a cleaning solution and a second cleaning tank containing a cleaning solution are prepared, and the substrate polished in the polishing step is immersed in the first cleaning tank and then in the second cleaning tank, and these immersions are repeated as necessary. The immersion time in the first cleaning tank (the immersion time per immersion in the case of multiple immersions) is not particularly limited, but may be, for example, 1 minute or more and 10 minutes or less. The immersion time in the second cleaning tank (the immersion time per immersion in the case of multiple immersions) is not particularly limited, but may be, for example, 1 minute or more and 30 minutes or less. The cleaning liquid is not particularly limited, but examples thereof include pure water and a solution of NH4OH (29% by mass): HO (31% by mass): deionized water (DIW) = 2:5.3:48 (volume ratio). Preferably, the cleaning liquid in the first cleaning tank is a solution of NH4OH (29% by mass): HO (31% by mass): deionized water (DIW) = 2:5.3:48 (volume ratio), and the cleaning liquid in the second cleaning tank is pure water. In this case, the cleaning liquid in the second cleaning tank is more preferably ultrapure water at 25°C. Immersion in the cleaning liquid may be performed with an ultrasonic oscillator operating. The temperature of the cleaning liquid is not particularly limited, but is preferably in the range of 40°C to 80°C. After cleaning, the substrate is preferably dried using a known drying device such as a spin dryer.

[0041] [Polishing composition] The polishing composition S1 and the polishing composition S2 used in the polishing method according to one embodiment of the present invention will be described below. The polishing composition S1 and the polishing composition S2 included in the polishing composition set according to another embodiment of the present invention will also be described below.

[0042] (abrasive grain) Polishing composition S1 and polishing composition S2 contain abrasive grains. In this specification, the abrasive grains contained in polishing composition S1 are referred to as abrasive grains 1, and the abrasive grains contained in polishing composition S2 are referred to as abrasive grains 2. Abrasive grains 1 function to physically polish the surface of the substrate. Abrasive grains 2 function to physically reduce residues on the surface of the substrate.

[0043] Abrasive grains include, but are not limited to, inorganic particles, organic particles, and organic-inorganic composite particles. Specific examples of inorganic particles include, but are not limited to, particles of oxides such as silica, alumina, cerium oxide, chromium oxide, titanium dioxide, zirconium oxide, magnesium oxide, manganese dioxide, zinc oxide, and red iron oxide (oxide particles), particles of nitrides such as silicon nitride and boron nitride (nitride particles), particles of carbides such as silicon carbide and boron carbide (carbide particles), diamond particles, and particles of carbonates such as calcium carbonate and barium carbonate. Specific examples of organic particles include, but are not limited to, particles of polymethyl methacrylate (PMMA). Also included are particles containing one or more of the above-listed materials. Among these, silica is preferred. That is, abrasive grains 1 and 2 are preferably silica. Specific examples of silica include colloidal silica, fumed silica, and sol-gel silica. Among these, colloidal silica or fumed silica is preferred, with colloidal silica being more preferred, from the viewpoint of further reducing surface defects on the polished surface of the substrate. Preferably, abrasive grains 1 and 2 each contain at least one type of particle selected from the group consisting of the particles listed above.

[0044] The average primary particle size of the abrasive grains is not particularly limited, but is preferably 1 nm or more, more preferably 5 nm or more, even more preferably 10 nm or more, and particularly preferably 20 nm or more. Within these ranges, the polishing rate is improved. The average primary particle size of the abrasive grains is also not particularly limited, but is preferably 100 nm or less, more preferably 70 nm or less, even more preferably 50 nm or less, and particularly preferably 30 nm or less. Within these ranges, surface defects on the polished surface of the substrate are further reduced. The average primary particle size of the abrasive grains is calculated, for example, from the specific surface area measured by the BET method. The specific surface area of ​​the abrasive grains can be measured, for example, using a Micromeritics FlowSorb II 2300. Examples of preferred ranges of the average primary particle size of the abrasive grains include, but are not limited to, 1 nm or more to 100 nm or less, 5 nm or more to 70 nm or less, 10 nm or more to 50 nm or less, and 20 nm or more to 30 nm or less.

[0045] The relationship between the average primary particle size of abrasive grains 1 and the average primary particle size of abrasive grains 2 is not particularly limited, but it is preferable that the average primary particle size of abrasive grains 2 be equal to or smaller than the average primary particle size of abrasive grains 1. Furthermore, the ratio of the average primary particle size of abrasive grains 2 to the average primary particle size of abrasive grains 1 (average primary particle size of abrasive grains 2 / average primary particle size of abrasive grains 1) is not particularly limited, but is preferably 0.1 or more and 1 or less, more preferably 0.4 or more and 1 or less, even more preferably 0.8 or more and 1 or less, and particularly preferably 1. In these cases, surface defects occurring on the polished surface of the substrate can be further reduced.

[0046] The average secondary particle diameter of the abrasive grains is not particularly limited, but is preferably 10 nm or more, more preferably 20 nm or more, and even more preferably 30 nm or more. Within these ranges, the polishing rate is improved. The average secondary particle diameter of the abrasive grains is also not particularly limited, but is preferably 200 nm or less, more preferably 150 nm or less, and even more preferably 100 nm or less. Within these ranges, surface defects occurring on the polished surface of the substrate are further reduced. The average secondary particle diameter of the abrasive grains can be measured, for example, by dynamic light scattering using a "UPA-UT151" model manufactured by Nikkiso Co., Ltd. Examples of preferred ranges of the average secondary particle diameter of the abrasive grains include, but are not limited to, 10 nm or more and 200 nm or less, 20 nm or more and 150 nm or less, and 30 nm or more and 100 nm or less.

[0047] The average degree of association of the abrasive grains is not particularly limited, but is preferably 1.2 or more, more preferably 1.4 or more, and even more preferably 1.5 or more. In this specification, the average degree of association refers to the value obtained by dividing the average secondary particle diameter of the abrasive grains by the average primary particle diameter. Within these ranges, the polishing rate is further improved. Furthermore, the average degree of association of the abrasive grains is not particularly limited, but is preferably 4 or less, more preferably 3.5 or less, and even more preferably 3 or less. Within these ranges, surface defects occurring on the polished surface of the substrate are further reduced. Examples of preferred ranges of the degree of association of the abrasive grains include, but are not limited to, 1.2 to 4, 1.4 to 3.5, and 1.5 to 3.

[0048] The abrasive grains may be commercially available or synthetic products, and may be used singly or in combination of two or more types.

[0049] The concentration of abrasive grains 1 in the polishing composition S1 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 0.05% by mass or more, relative to the total mass of the polishing composition S1. Within these ranges, the polishing rate is improved. Furthermore, the concentration of abrasive grains 1 in the polishing composition S1 is not particularly limited, but is preferably 3% by mass or less, more preferably 1% by mass or less, even more preferably 0.5% by mass or less, even more preferably 0.1% by mass or less, and particularly preferably 0.08% by mass or less, relative to the total mass of the polishing composition S1. Within these ranges, surface defects occurring on the polished surface of the substrate are further reduced. Examples of preferred ranges of the concentration of abrasive grain 1 in polishing composition S1 include, but are not limited to, 0.001% by mass or more and 3% by mass or less, 0.01% by mass or more and 1% by mass or less, 0.05% by mass or more and 0.5% by mass or less, 0.05% by mass or more and 0.1% by mass or less, and 0.05% by mass or more and 0.08% by mass or less, relative to the total mass of polishing composition S1.

[0050] The concentration of abrasive grains 2 in polishing composition S2 is not particularly limited, but is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, based on the total mass of polishing composition S2. Within these ranges, the polishing rate is improved. Furthermore, the concentration of abrasive grains 2 in polishing composition S2 is not particularly limited, but is preferably 3% by mass or less, more preferably 1% by mass or less, even more preferably 0.5% by mass or less, even more preferably 0.1% by mass or less, and particularly preferably 0.08% by mass or less, based on the total mass of polishing composition S2. Within these ranges, surface defects occurring on the polished surface of the substrate are further reduced. Examples of preferred concentrations of abrasive grains 2 in polishing composition S2 include, but are not limited to, 0.001% by mass or more and 3% by mass or less, 0.01% by mass or more and 1% by mass or less, 0.01% by mass or more and 0.5% by mass or less, 0.01% by mass or more and 0.1% by mass or less, and 0.01% by mass or more and 0.08% by mass or less, relative to the total mass of polishing composition S2.

[0051] Based on the above, in a preferred embodiment of the present invention, the concentration of abrasive grains 1 in polishing composition S1 is 0.001 mass% or more and 3 mass% or less relative to the total mass of polishing composition S1, and the concentration of abrasive grains 2 in polishing composition S2 is 0.001 mass% or more and 3 mass% or less relative to the total mass of polishing composition S2.

[0052] The relationship between the concentration of abrasive grains 2 in polishing composition S2 and the concentration of abrasive grains 1 in polishing composition S1 is not particularly limited, but it is preferable that the concentration of abrasive grains 2 in polishing composition S2 be equal to or lower than the concentration of abrasive grains 1 in polishing composition S1. Furthermore, the ratio of the concentration of abrasive grains 2 in polishing composition S2 to the concentration of abrasive grains 1 in polishing composition S1 (concentration of abrasive grains 2 in polishing composition S2 / concentration of abrasive grains 1 in polishing composition S1) is not particularly limited, but is preferably 0.1 or more and 1 or less, more preferably 0.4 or more and 1 or less. In these cases, surface defects occurring on the polished surface of the substrate can be further reduced. The ratio can be, for example, 0.8 or more and 1 or less, for example, 1.

[0053] (Water-soluble polymer) Polishing composition S1 and polishing composition S2 contain a water-soluble polymer. In this specification, "water-soluble" means that the solubility in water (25°C) is 1 g / 100 mL or more, and "polymer" refers to a compound with a weight-average molecular weight of 1,000 or more. The weight-average molecular weight can be measured by gel permeation chromatography (GPC) in terms of polyoxyethylene. Specifically, values ​​measured by the method described in the Examples can be used.

[0054] Polishing composition S1 contains a water-soluble polymer having an abrasive adsorption parameter of 5 or more, calculated by the procedures (1) to (4) described below (hereinafter also referred to simply as "abrasive adsorption parameter"). Preferably, polishing composition S1 further contains a water-soluble polymer having an abrasive adsorption parameter of less than 5. Polishing composition S2 contains a water-soluble polymer having an abrasive adsorption parameter of less than 5. Polishing composition S2 does not contain a water-soluble polymer having an abrasive adsorption parameter of 5 or more in a content (concentration) of 0.005% by mass or more. That is, the concentration of the water-soluble polymer having an abrasive adsorption parameter of 5 or more in polishing composition S2 is less than 0.005% by mass (less than 0.005% by mass relative to the total mass of polishing composition S2). The water-soluble polymer having an abrasive adsorption parameter of 5 or more functions to protect the surface of the abrasive. The water-soluble polymer having an abrasive adsorption parameter of less than 5 functions to reduce residue on the surface of the substrate.

[0055] The abrasive adsorption parameter of a water-soluble polymer can be calculated by the following steps (1) to (4): (1) Prepare a test solution L containing 0.08% by mass of colloidal silica (PL-2 manufactured by Fuso Chemical Co., Ltd., average primary particle size 25 nm, average secondary particle size 50 nm), 0.004% by mass of the water-soluble polymer to be measured, and 0.005% by mass of ammonia, with the remainder being water. (2) The total organic carbon concentration (TOC value) of the test liquid L is measured, and the obtained TOC value is defined as the total organic carbon concentration W0 [ppm by mass] of the water-soluble polymer to be measured contained in the test liquid L. (3) The test liquid L is centrifuged at 26,000 rpm for 30 minutes using a centrifuge such as the Avanti HP-30I manufactured by Beckman Coulter, Inc. to separate the sediment from the supernatant, and the TOC value of the supernatant is measured. The obtained TOC value is defined as the total organic carbon concentration W1 [ppm by mass] of the water-soluble polymer to be measured contained in the supernatant. (4) The adsorption ratio of the water-soluble polymer to be measured is calculated using the following formula, and this value is used as the abrasive adsorption parameter.

[0056]

number

[0057] The total organic carbon concentration W0 [ppm by mass] of the water-soluble polymer to be measured contained in the test liquid L and the total organic carbon concentration W1 [ppm by mass] of the water-soluble polymer to be measured contained in the supernatant after centrifugal separation of the test liquid L can be evaluated using, for example, a total organic carbon meter TOC-L manufactured by Shimadzu Corporation.

[0058] The method for calculating the abrasive adhesion parameter will be described in detail in the Examples.

[0059] It is believed that colloidal silica precipitates due to the centrifugation of test liquid L. Furthermore, it is believed that the water-soluble polymer contained in the supernatant liquid after the centrifugation of test liquid L is mainly the portion of the water-soluble polymer that is not adsorbed to colloidal silica.

[0060] It is believed that as the abrasive adsorption parameter increases, the amount of water-soluble polymer contained in the supernatant liquid after centrifugal separation of test liquid L decreases, and the amount of water-soluble polymer adsorbed to colloidal silica increases. Therefore, it is presumed that the larger the abrasive adsorption parameter of the water-soluble polymer, the easier it will be for the water-soluble polymer to adsorb to abrasive grains in an actual polishing composition, and the greater the amount of adsorption.

[0061] For water-soluble polymers having an abrasive adsorption parameter of less than 5, the abrasive adsorption parameter is not particularly limited, but is usually greater than or equal to 0. Also, the abrasive adsorption parameter is not particularly limited, but is preferably less than or equal to 2. Within these ranges, surface defects occurring on the polished surface of the substrate are further reduced.

[0062] For water-soluble polymers having an abrasive adsorption parameter of 5 or more, the abrasive adsorption parameter is not particularly limited, but is preferably 60 or more. Within this range, surface defects occurring on the polished surface of the substrate are further reduced. Furthermore, the abrasive adsorption parameter is not particularly limited, but is usually 100 or less.

[0063] The water-soluble polymer used in the present invention is not particularly limited, and examples thereof include polymers having at least one functional group selected from the group consisting of a cationic group, an anionic group, and a nonionic group in the molecule.Specific examples include polymers having in the molecule a hydroxyl group, a carboxyl group or a salt thereof, an acyloxy group, a sulfo group or a salt thereof, a partial structure containing a nitrogen atom (e.g., an amide group, an amidino group, an imino group, an imide group, a quaternary nitrogen structure, a heterocyclic structure containing a nitrogen atom as a ring-forming atom), a heterocyclic structure containing a heteroatom other than a nitrogen atom as a ring-forming atom, a vinyl structure, a polyoxyalkylene structure, etc.

[0064] The water-soluble polymer having an abrasive adsorption parameter of 5 or more is not particularly limited, but preferred examples include cellulose derivatives, polymers having a partial structure containing a nitrogen atom in the molecule, polymers containing two or more hydroxy groups in the molecule and having an unsubstituted polyoxyalkylene structure, etc. The water-soluble polymer having an abrasive adsorption parameter of 5 or more contained in the polishing composition S1 preferably includes at least one selected from the group consisting of these compounds.

[0065] The cellulose derivative is not particularly limited, but examples thereof include hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, ethyl cellulose, ethyl hydroxyethyl cellulose, and carboxymethyl cellulose.

[0066] The polymer having a partial structure containing a nitrogen atom in the molecule is not particularly limited, and examples thereof include poly(meth)acrylamide, polyalkylaminoalkyl(meth)acrylamide, polyhydroxyalkyl(meth)acrylamide, poly-N-(meth)acryloylmorpholine, poly-N-vinylpyrrolidone, copolymers containing poly-N-vinylpyrrolidone as part of their structure, poly-N-vinylimidazole, poly-N-vinylcarbazole, poly-N-vinylcaprolactam, copolymers containing poly-N-vinylcaprolactam as part of their structure, poly-N-vinylpiperidine, polyamidine, polyethyleneimine, hydrophilized polyimides, various polyamino acids, and imine derivatives such as poly(N-acylalkyleneimine).

[0067] The polymer containing two or more hydroxy groups in the molecule and an unsubstituted polyoxyalkylene structure is not particularly limited, but examples thereof include polyethylene oxide (PEO), polypropylene oxide (PPO), polybutylene oxide (PBO), a block copolymer of ethylene oxide (EO) and propylene oxide (PO), and a random copolymer of EO and PO.

[0068] Among these, from the viewpoint of further reducing surface defects that occur on the polished surface of the substrate, hydroxyethyl cellulose or poly-N-(meth)acryloylmorpholine is preferred, and poly-N-acryloylmorpholine is more preferred.

[0069] The weight-average molecular weight of a water-soluble polymer having an abrasive adsorption parameter of 5 or more is not particularly limited, but is preferably 1,000 or more, more preferably 10,000 or more, even more preferably 100,000 or more, and particularly preferably 200,000 or more. The weight-average molecular weight of a water-soluble polymer having an abrasive adsorption parameter of 5 or more can be, for example, 300,000 or more. The weight-average molecular weight of a water-soluble polymer having an abrasive adsorption parameter of 5 or more is not particularly limited, but is preferably 2,000,000 or less, more preferably 1,500,000 or less, even more preferably 1,000,000 or less, and particularly preferably 500,000 or less. Within these ranges, surface defects occurring on the polished surface of the substrate are further reduced. The weight-average molecular weight of a water-soluble polymer having an abrasive adsorption parameter of 5 or more can be measured in polyoxyethylene equivalent by gel permeation chromatography (GPC). Specific measurement methods are described in the Examples. Preferred examples of the weight average molecular weight of the water-soluble polymer having an abrasive adsorption parameter of 5 or more include, but are not limited to, 1,000 to 2,000,000, 10,000 to 1,500,000, 100,000 to 1,000,000, 200,000 to 500,000, and 300,000 to 500,000.

[0070] The water-soluble polymer having an abrasive adsorption parameter of less than 5 is not particularly limited, but preferred examples include a polymer containing two or more hydroxy groups in the molecule and containing a substituted polyoxyalkylene structure, a polymer containing two or more hydroxy groups in the molecule and containing a structural unit derived from vinyl alcohol, a polymer having an anionic group in the molecule, etc. The water-soluble polymer having an abrasive adsorption parameter of less than 5 contained in the polishing composition S2 preferably contains at least one selected from the group consisting of these compounds.

[0071] In a polymer having a substituted polyoxyalkylene structure and containing two or more hydroxy groups in the molecule, a hydroxy group is preferred as a substituent substituting the polyoxyalkylene group. The polymer having a substituted polyoxyalkylene structure and containing two or more hydroxy groups in the molecule is not particularly limited, but examples thereof include polyglycerin.

[0072] In a polymer containing two or more hydroxy groups in the molecule and a structural unit derived from vinyl alcohol, the structural unit derived from vinyl alcohol refers to a vinyl alcohol unit (a structural moiety represented by -CH-CH(OH)-; hereinafter also referred to as a "VA unit"). Furthermore, a polymer containing two or more hydroxy groups in the molecule and a structural unit derived from vinyl alcohol may be a copolymer containing, in addition to VA units, non-vinyl alcohol units (structural units derived from monomers other than vinyl alcohol; hereinafter also referred to as a "non-VA unit"). Examples of non-VA units include, but are not limited to, structural units derived from ethylene, vinyl acetate, vinyl propionate, vinyl hexanoate, 2-butenediol, and the like. When a polymer containing a structural unit derived from vinyl alcohol contains non-VA units, it may contain only one type of non-VA unit, or two or more types of non-VA units. In a polymer containing two or more hydroxy groups in the molecule and a structural unit derived from vinyl alcohol, the proportion of the number of moles of VA units in the number of moles of all repeating units is not particularly limited, but is preferably 50% or more, more preferably 65% ​​or more, even more preferably 70% or more, and particularly preferably 75% or more (up to 100%). All repeating units may be substantially composed of VA units. The saponification degree of polyvinyl alcohol is not particularly limited, but is preferably 50% or more by mole, more preferably 65% ​​or more by mole, even more preferably 70% or more, and particularly preferably 75% or more by mole (up to 100%). Examples of polymers containing two or more hydroxy groups in the molecule and a structural unit derived from vinyl alcohol include, but are not limited to, polyvinyl alcohol (PVA), acetalized polyvinyl alcohol, vinyl alcohol-ethylene copolymer, and vinyl alcohol-butenediol copolymer. When the polymer containing a structural unit derived from vinyl alcohol is acetalized polyvinyl alcohol, the type of acetalization is not particularly limited, and examples thereof include polyvinyl formal, polyvinyl acetoacetal, polyvinyl propylal, polyvinyl ethylal, and polyvinyl butyral.The degree of acetalization is not particularly limited, but is preferably 1 mol % or more and 50 mol % or less, more preferably 10 mol % or more and 45 mol % or less, and even more preferably 20 mol % or more and 40 mol % or less.

[0073] The polymer having an anionic group in the molecule is not particularly limited, but preferable examples include a polymer having a carboxy group or a salt group thereof in the molecule, a polymer having a sulfo group or a salt group thereof in the molecule, etc. Specific examples include poly(meth)acrylic acid, poly(meth)acrylamidoalkylsulfonic acid, polyisoprene sulfonic acid, polyvinyl sulfonic acid, polyallyl sulfonic acid, polyisoamylene sulfonic acid, polystyrene sulfonic acid, and salts thereof.

[0074] Among these, from the viewpoint of further reducing surface defects occurring on the polished surface of the substrate, polymers containing two or more hydroxy groups in the molecule and having structural units derived from vinyl alcohol are preferred, polyvinyl alcohol or acetalized polyvinyl alcohol are more preferred, and acetalized polyvinyl alcohol is even more preferred.

[0075] Based on these considerations, in a preferred embodiment of the present invention, the water-soluble polymer having an abrasive adsorption parameter of 5 or greater is at least one polymer selected from the group consisting of cellulose derivatives, polymers containing a partial structure containing a nitrogen atom in the molecule, and polymers containing two or more hydroxy groups in the molecule and an unsubstituted polyoxyalkylene structure, and the water-soluble polymer having an abrasive adsorption parameter of less than 5 is at least one polymer selected from the group consisting of polymers containing two or more hydroxy groups in the molecule and a substituted polyoxyalkylene structure, polymers containing two or more hydroxy groups in the molecule and a structural unit derived from vinyl alcohol, and polymers containing an anionic group in the molecule.

[0076] The weight-average molecular weight of a water-soluble polymer having an abrasive adsorption parameter of less than 5 is not particularly limited as long as it is 1,000 or more, but is preferably 2,000 or more, more preferably 5,000 or more, even more preferably 9,000 or more, even more preferably 10,000 or more, and particularly preferably 12,000 or more. The weight-average molecular weight of a water-soluble polymer having an abrasive adsorption parameter of less than 5 is not particularly limited, but is preferably 2,000,000 or less, more preferably 1,000,000 or less, even more preferably 500,000 or less, even more preferably 100,000 or less, and particularly preferably 80,000 or less. Within these ranges, surface defects occurring on the polished surface of the substrate are further reduced. The weight-average molecular weight of a water-soluble polymer having an abrasive adsorption parameter of less than 5 can be, for example, 50,000 or less. The weight-average molecular weight of a water-soluble polymer having an abrasive adsorption parameter of less than 5 can be measured in polyoxyethylene terms by gel permeation chromatography (GPC). Specific measurement methods are described in the Examples. Examples of preferred ranges of the weight-average molecular weight of a water-soluble polymer having an abrasive adsorption parameter of less than 5 include, but are not limited to, 2,000 to 2,000,000, 5,000 to 1,000,000, 9,000 to 500,000, 9,000 to 100,000, 9,000 to 80,000, and 9,000 to 50,000.

[0077] The water-soluble polymer having an abrasive adsorption parameter of 5 or more and the water-soluble polymer having an abrasive adsorption parameter of less than 5 may be either a commercially available product or a synthetic product. The water-soluble polymer having an abrasive adsorption parameter of 5 or more and the water-soluble polymer having an abrasive adsorption parameter of less than 5 may each be used alone or in combination of two or more.

[0078] The concentration of the water-soluble polymer having an abrasive adsorption parameter of 5 or more in the polishing composition S1 is not particularly limited, but is preferably 0.0001 mass% or more, more preferably 0.001 mass% or more, even more preferably 0.003 mass% or more, and particularly preferably 0.004 mass% or more, relative to the total mass of the polishing composition S1. Within these ranges, surface defects occurring on the polished surface of the substrate are further reduced. This is presumably due to improved protection of the abrasive grains in the polishing stage 1. Furthermore, the concentration of the water-soluble polymer having an abrasive adsorption parameter of 5 or more in the polishing composition S1 is not particularly limited, but is preferably 1 mass% or less, more preferably 0.01 mass% or less, relative to the total mass of the polishing composition S1. Within these ranges, surface defects occurring on the polished surface of the substrate are further reduced. This is presumably due to reduced amounts of the water-soluble polymer having an abrasive adsorption parameter of 5 or more remaining after the polishing stage 1. The concentration of the water-soluble polymer having an abrasive adsorption parameter of 5 or more in the polishing composition S1 can be, for example, 0.008% by mass or less, e.g., 0.005% by mass or less, relative to the total mass of the polishing composition S1. Preferred examples of the concentration range of the water-soluble polymer having an abrasive adsorption parameter of 5 or more in the polishing composition S1 include, but are not limited to, 0.0001% by mass or more and 1% by mass or less, 0.001% by mass or more and 0.01% by mass or less, 0.003% by mass or more and 0.008% by mass or less, and 0.004% by mass or more and 0.005% by mass or less, relative to the total mass of the polishing composition S1.

[0079] When the polishing composition S1 contains a water-soluble polymer having an abrasive adsorption parameter of less than 5, the concentration of the water-soluble polymer having an abrasive adsorption parameter of less than 5 in the polishing composition S1 is not particularly limited, but is preferably 0.0001% by mass or more, more preferably 0.001% by mass or more, even more preferably 0.002% by mass or more, and particularly preferably 0.003% by mass or more, relative to the total mass of the polishing composition S1. Within these ranges, surface defects occurring on the polished surface of the substrate are further reduced. This is presumably because the presence of the water-soluble polymer having an abrasive adsorption parameter of less than 5 reduces the number of abrasives and water-soluble polymers having an abrasive adsorption parameter of 5 or more remaining after polishing stage 1. Furthermore, the concentration of the water-soluble polymer having an abrasive adsorption parameter of less than 5 in the polishing composition S1 is not particularly limited, but is preferably 1% by mass or less, more preferably 0.01% by mass or less, relative to the total mass of the polishing composition S1. Within these ranges, surface defects occurring on the polished surface of the substrate are further reduced. The reason for this is presumably that the water-soluble polymer having an abrasive adsorption parameter of less than 5 is less likely to inhibit the adsorption of abrasives and water-soluble polymers having an abrasive adsorption parameter of 5 or more to the substrate in polishing stage 1, thereby achieving a better defect removal effect in polishing stage 1. The concentration of the water-soluble polymer having an abrasive adsorption parameter of less than 5 in polishing composition S1 can be, for example, 0.008% by mass or less, e.g., 0.005% by mass or less, relative to the total mass of polishing composition S1. Preferred examples of the concentration range of the water-soluble polymer having an abrasive adsorption parameter of less than 5 in polishing composition S1 include, but are not limited to, 0.0001% by mass or more and 1% by mass or less, 0.001% by mass or more and 0.01% by mass or less, 0.002% by mass or more and 0.008% by mass or less, and 0.003% by mass or more and 0.005% by mass or less, relative to the total mass of polishing composition S1.

[0080] For these reasons, the concentration of the water-soluble polymer in the polishing composition S1 (i.e., the sum of the concentration of the water-soluble polymer having an abrasive adsorption parameter of 5 or more and the concentration of the water-soluble polymer having an abrasive adsorption parameter of less than 5 in the polishing composition S1, the same applies hereinafter) is not particularly limited, but is preferably 0.0001% by mass or more, more preferably 0.001% by mass or more, even more preferably 0.003% by mass or more, and particularly preferably 0.004% by mass or more, relative to the total mass of the polishing composition S1. Furthermore, the concentration of the water-soluble polymer in the polishing composition S1 is not particularly limited, but is preferably 2% by mass or less, more preferably 0.02% by mass or less, even more preferably 0.016% by mass or less, and particularly preferably 0.01% by mass or less, relative to the total mass of the polishing composition S1. Within these ranges, surface defects occurring on the polished surface of the substrate are further reduced. Examples of preferred concentrations of the water-soluble polymer in the polishing composition S1 include, but are not limited to, 0.0001% by mass or more and 2% by mass or less, 0.001% by mass or more and 0.02% by mass or less, 0.003% by mass or more and 0.016% by mass or less, and 0.004% by mass or more and 0.01% by mass or less, relative to the total mass of the polishing composition S1.

[0081] The concentration of the water-soluble polymer having an abrasive adsorption parameter of less than 5 in the polishing composition S2 is not particularly limited, but is preferably 0.0001% by mass or more, more preferably 0.001% by mass or more, even more preferably 0.002% by mass or more, and particularly preferably 0.003% by mass or more, relative to the total mass of the polishing composition S2. Within these ranges, surface defects on the polished surface of the substrate are further reduced. This is presumably due to improved cleaning efficiency in the polishing stage 2, i.e., improved abrasive and water-soluble polymer reduction. Furthermore, the concentration of the water-soluble polymer having an abrasive adsorption parameter of less than 5 in the polishing composition S2 is not particularly limited, but is preferably 1% by mass or less, more preferably 0.01% by mass or less, and even more preferably 0.008% by mass or less, relative to the total mass of the polishing composition S2. Within these ranges, surface defects on the polished surface of the substrate are further reduced. This is presumably due to reduced amounts of water-soluble polymer having an abrasive adsorption parameter of less than 5 remaining after the polishing stage 2. The concentration of the water-soluble polymer having an abrasive adsorption parameter of less than 5 in the polishing composition S2 can be, for example, 0.005% by mass or less, relative to the total mass of the polishing composition S2. Preferred examples of the concentration of the water-soluble polymer having an abrasive adsorption parameter of less than 5 in the polishing composition S2 include, but are not limited to, 0.0001% by mass or more and 1% by mass or less, 0.001% by mass or more and 0.01% by mass or less, 0.002% by mass or more and 0.008% by mass or less, and 0.003% by mass or more and 0.005% by mass or less, relative to the total mass of the polishing composition S2.

[0082] Polishing composition S2 does not contain a water-soluble polymer having an abrasive adsorption parameter of 5 or more at a content (concentration) of 0.005% by mass or more. The concentration of the water-soluble polymer having an abrasive adsorption parameter of 5 or more in polishing composition S2 is not particularly limited as long as it is less than 0.005% by mass (less than 0.005% by mass relative to the total mass of polishing composition S2). However, polishing composition S2 preferably does not substantially contain a water-soluble polymer having an abrasive adsorption parameter of 5 or more, and most preferably does not contain a water-soluble polymer having an abrasive adsorption parameter of 5 or more. In this specification, the phrase "substantially does not contain a water-soluble polymer having an abrasive adsorption parameter of 5 or more" means that the concentration of the water-soluble polymer having an abrasive adsorption parameter of 5 or more is less than 0.0001% by mass relative to the total mass of polishing composition S2. In this case, surface defects occurring on the polished surface of the substrate are further reduced. The reason for this is presumably that fewer water-soluble polymers with an abrasive adsorption parameter of 5 or greater remain after polishing stage 2, and the effect of removing abrasives and water-soluble polymers in polishing stage 2 is less likely to be hindered, resulting in a more effective reduction of abrasives and water-soluble polymers in polishing stage 2. Preferred examples of the concentration of the water-soluble polymer with an abrasive adsorption parameter of 5 or greater in polishing composition S2 include, but are not limited to, less than 0.0001% by mass relative to the total mass of polishing composition S2, and no water-soluble polymer with an abrasive adsorption parameter of 5 or greater.

[0083] For these reasons, the concentration of the water-soluble polymer in the polishing composition S2 (i.e., the sum of the concentration of the water-soluble polymer having an abrasive adsorption parameter of 5 or more and the concentration of the water-soluble polymer having an abrasive adsorption parameter of less than 5 in the polishing composition S2, the same applies hereinafter) is not particularly limited, but is preferably 0.0001% by mass or more, more preferably 0.001% by mass or more, even more preferably 0.002% by mass or more, and particularly preferably 0.003% by mass or more, relative to the total mass of the polishing composition S2. Furthermore, the concentration of the water-soluble polymer in the polishing composition S2 is not particularly limited, but is preferably 1% by mass or less, more preferably 0.01% by mass or less, even more preferably 0.008% by mass or less, and particularly preferably 0.005% by mass or less, relative to the total mass of the polishing composition S2. In these cases, the surface defects occurring on the polished surface of the substrate are further reduced. Examples of preferred concentrations of the water-soluble polymer in the polishing composition S2 include, but are not limited to, 0.0001% by mass or more and 1% by mass or less, 0.001% by mass or more and 0.01% by mass or less, 0.002% by mass or more and 0.008% by mass or less, and 0.003% by mass or more and 0.005% by mass or less, relative to the total mass of the polishing composition S2.

[0084] Therefore, in one preferred embodiment of the present invention, the concentration of the water-soluble polymer in the polishing composition S1 is 0.0001 mass% or more and 2 mass% or less relative to the total mass of the polishing composition S1, and the concentration of the water-soluble polymer in the polishing composition S2 is 0.0001 mass% or more and 1 mass% or less relative to the total mass of the polishing composition S2.

[0085] The relationship between the concentration of the water-soluble polymer in the polishing composition S2 and the concentration of the water-soluble polymer in the polishing composition S1 is not particularly limited, but it is preferable that the concentration of the water-soluble polymer in the polishing composition S2 is equal to or lower than the concentration of the water-soluble polymer in the polishing composition S1. Furthermore, the ratio of the concentration of the water-soluble polymer in the polishing composition S2 to the concentration of the water-soluble polymer in the polishing composition S1 (concentration of the water-soluble polymer in the polishing composition S2 / concentration of the water-soluble polymer in the polishing composition S1) is not particularly limited, but is preferably 0.1 or more and 1 or less, more preferably 0.2 or more and 0.95 or less. In these cases, the surface defects occurring on the polished surface of the substrate can be further reduced. Furthermore, the ratio can be, for example, 0.3 or more and 0.6 or less, for example, 0.4 or more and 0.5 or less.

[0086] (basic compounds) The polishing composition S1 and the polishing composition S2 may each independently further contain a basic compound.Moreover, it is more preferable that the polishing composition S1 and the polishing composition S2 further contain a basic compound.Depending on the type of substrate, the basic compound may exert a chemical effect on the polishing surface of the substrate, thereby chemically polishing the substrate.

[0087] The basic compound is not particularly limited, but examples thereof include hydroxides of alkali metals or alkaline earth metals or salts thereof, quaternary ammonium, ammonia, quaternary ammonium hydroxides or salts thereof, amines, and the like.

[0088] Specific examples of alkali metals include, but are not limited to, potassium and sodium. Specific examples of alkaline earth metals include, but are not limited to, calcium. Specific examples of salts of alkali metals or alkaline earth metals include, but are not limited to, carbonates, bicarbonates, sulfates, acetates, and the like. Specific examples of hydroxides or salts of alkali metals or alkaline earth metals include, but are not limited to, calcium hydroxide, potassium hydroxide, potassium carbonate, potassium bicarbonate, potassium sulfate, potassium acetate, potassium chloride, sodium hydroxide, sodium bicarbonate, sodium carbonate, calcium hydroxide, and the like.

[0089] Specific examples of quaternary ammonium include, but are not limited to, tetramethylammonium, tetraethylammonium, and tetrabutylammonium.

[0090] Specific examples of the quaternary ammonium hydroxide or its salts include, but are not limited to, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, and the like.

[0091] Specific examples of amines include compounds having a structure represented by the following chemical formula (I), triethylenetetramine, anhydrous piperazine, piperazine hexahydrate, 1-(2-aminoethyl)piperazine, N-methylpiperazine, guanidine, and azoles such as imidazole and triazole.

[0092] [ka]

[0093] In the above chemical formula (I), R 1 ~R 3 are each independently a hydrogen atom or a substituted or unsubstituted alkyl group; However, R 1 ~R 3 The case where all of are hydrogen atoms is excluded.

[0094] R 1 ~R 3 When each of the groups is a substituted alkyl group, the substituent contained in the substituted alkyl group is not particularly limited, but is preferably a hydroxy group or a substituted or unsubstituted amino group, and more preferably a hydroxy group or an unsubstituted amino group.

[0095] R 1 ~R 3 When each of the groups is a substituted or unsubstituted alkyl group, the number of carbon atoms in the alkyl group (in the case of a substituted alkyl group, the alkyl group in an unsubstituted state) is not particularly limited, but is preferably 1 or more and 6 or less, more preferably 2 or more and 3 or less, and particularly preferably 2.

[0096] Preferred specific examples of amines include, but are not limited to, methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, ethylenediamine, monoethanolamine, diethanolamine, triethanolamine, N-(β-aminoethyl)ethanolamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, anhydrous piperazine, piperazine hexahydrate, 1-(2-aminoethyl)piperazine, N-methylpiperazine, guanidine, azoles such as imidazole and triazole, etc. The amines contained in polishing composition S1 and polishing composition S2 each preferably contain at least one compound selected from the group consisting of these compounds.

[0097] Among these, quaternary ammonium, ammonia, quaternary ammonium hydroxide or its salt, and amine are preferred. As the basic compound contained in the polishing composition S1, quaternary ammonium, ammonia, quaternary ammonium hydroxide or its salt are more preferred, and anhydrous ammonium is even more preferred. The basic compound contained in the polishing composition S1 preferably contains at least one compound selected from the group consisting of these compounds. The basic compound contained in the polishing composition S2 is preferably ammonia or a compound having a structure represented by the above chemical formula (1), more preferably ammonia, methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, ethylenediamine, monoethanolamine, diethanolamine, triethanolamine, N-(β-aminoethyl)ethanolamine, hexamethylenediamine, diethylenetriamine, more preferably ammonia, trimethylamine, ethylamine, diethylamine, triethylamine, triethanolamine, more preferably trimethylamine, ethylamine, diethylamine, triethylamine, triethanolamine, more preferably trimethylamine, ethylamine, triethylamine, triethanolamine, more preferably trimethylamine, ethylamine, triethylamine, triethanolamine, more preferably trimethylamine, ethylamine, triethylamine, more preferably ethylamine, triethylamine, and particularly preferably triethylamine. The basic compound contained in the polishing composition S2 preferably contains at least one compound selected from the group consisting of these compounds.

[0098] The basic compound may be a commercially available product or a synthetic product, and may be used alone or in combination of two or more types.

[0099] The concentration of the basic compound in the polishing composition S1 is not particularly limited, but is preferably 0.0001% by mass or more, more preferably 0.001% by mass or more, even more preferably 0.003% by mass or more, and particularly preferably 0.004% by mass or more, relative to the total mass of the polishing composition S1. Within these ranges, the polishing rate is further improved. The concentration of the basic compound in the polishing composition S1 is not particularly limited, but is preferably 1% by mass or less, more preferably 0.01% by mass or less, and even more preferably 0.008% by mass or less, relative to the total mass of the polishing composition S1. Within these ranges, the surface defects occurring on the polished surface of the substrate are further reduced. Preferred examples of the concentration of the basic compound in the polishing composition S1 include, but are not limited to, 0.0001% by mass or more and 1% by mass or less, 0.001% by mass or more and 0.01% by mass or less, 0.003% by mass or more and 0.008% by mass or less, and 0.004% by mass or more and 0.008% by mass or less, relative to the total mass of the polishing composition S1.

[0100] The concentration of the basic compound in the polishing composition S2 is not particularly limited, but is preferably 0.0001% by mass or more, more preferably 0.0004% by mass or more, even more preferably 0.0008% by mass or more, even more preferably 0.001% by mass or more, particularly preferably 0.003% by mass or more, and even more particularly preferably 0.004% by mass or more, relative to the total mass of the polishing composition S2. Within these ranges, the surface defects occurring on the polished surface of the substrate are further reduced. The concentration of the basic compound in the polishing composition S2 is not particularly limited, but is preferably 1% by mass or less, more preferably 0.1% by mass or less, even more preferably 0.01% by mass or less, even more preferably 0.008% by mass or less, particularly preferably 0.005% by mass or less, and even more particularly preferably 0.003% by mass or less, relative to the total mass of the polishing composition S2. Within these ranges, the surface defects occurring on the polished surface of the substrate are further reduced. Preferred examples of the concentration of the basic compound in the polishing composition S1 include, but are not limited to, 0.0001% by mass or more and 1% by mass or less, 0.0004% by mass or more and 0.1% by mass or less, 0.0008% by mass or more and 0.01% by mass or less, 0.0008% by mass or more and 0.008% by mass or less, 0.0008% by mass or more and 0.005% by mass or less, and 0.0008% by mass or more and 0.003% by mass or less, relative to the total mass of the polishing composition S1.

[0101] (surfactant) The polishing composition S1 and the polishing composition S2 may each independently further contain a surfactant. In addition, it is preferable that the polishing composition S1 and the polishing composition S2 further contain a surfactant. The surfactant acts to suppress roughness of the polished surface of the substrate and reduce surface defects. In particular, when a basic compound is contained in the polishing composition, chemical polishing by the basic compound tends to easily cause roughness on the polished surface of the substrate. For this reason, the combined use of a basic compound and a surfactant is particularly effective.

[0102] The surfactant is not particularly limited, but examples thereof include nonionic surfactants, cationic surfactants, anionic surfactants, etc. Among these, nonionic surfactants are preferred from the viewpoint of further reducing surface defects that occur on the polished surface of the substrate.

[0103] The nonionic surfactant is not particularly limited, but examples thereof include oxyalkylene homopolymers, copolymers of multiple types of oxyalkylenes, polyoxyalkylene adducts, etc. Specific examples of the polyoxyalkylene adducts are not particularly limited, but include polyoxyalkylene alkyl ethers, polyoxyalkylene alkylphenyl ethers, polyoxyalkylene alkylamines, polyoxyalkylene fatty acid esters, polyoxyalkylene glycerol ether fatty acid esters, polyoxyalkylene sorbitan fatty acid esters, etc.

[0104] Specific examples of nonionic surfactants include, but are not limited to, polyoxyethylene propyl ether, polyoxyethylene butyl ether, polyoxyethylene pentyl ether, polyoxyethylene hexyl ether, polyoxyethylene octyl ether, polyoxyethylene-2-ethylhexyl ether, polyoxyethylene nonyl ether, polyoxyethylene decyl ether, polyoxyethylene isodecyl ether, polyoxyethylene tridecyl ether, polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene isostearyl ether, polyoxyethylene oleyl ether, polyoxyethylene phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene nonyl phenyl ether, and polyoxyethylene dodecyl phenyl ether. Examples of the hydroxybenzoates include hydroxybenzoates, polyoxyethylene styrenated phenyl ether, polyoxyethylene laurylamine, polyoxyethylene stearylamine, polyoxyethylene oleylamine, polyoxyethylene stearylamide, polyoxyethylene oleylamide, polyoxyethylene monolaurate, polyoxyethylene monostearate, polyoxyethylene distearate, polyoxyethylene monooleate, polyoxyethylene dioleate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopaltimate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan trioleate, polyoxyethylene sorbitan tetraoleate, polyoxyethylene castor oil, and polyoxyethylene hydrogenated castor oil.

[0105] Among these, from the viewpoint of further reducing surface defects that occur on the polished surface of the substrate, polyoxyalkylene adducts and the like are preferred, polyoxyalkylene alkyl ethers are more preferred, polyoxyethylene alkyl ethers are even more preferred, and polyoxyethylene decyl ether is particularly preferred.

[0106] The molecular weight of the surfactant is not particularly limited, but is preferably less than 1,000, more preferably less than 500, and even more preferably less than 400. The molecular weight of the surfactant is preferably calculated from the chemical formula.

[0107] The surfactant may be a commercially available product or a synthetic product, and may be used alone or in combination of two or more types.

[0108] The surfactants contained in the polishing compositions S1 and S2 each preferably contain a nonionic surfactant. The nonionic surfactants contained in the polishing compositions S1 and S2 each preferably contain at least one selected from the group consisting of the compounds listed above.

[0109] The concentration of the surfactant in the polishing composition S1 is not particularly limited, but is preferably 0.0001% by mass or more, more preferably 0.0002% by mass or more, and even more preferably 0.0004% by mass or more, relative to the total mass of the polishing composition S1. Within these ranges, surface defects occurring on the polished surface of the substrate are further reduced. Furthermore, the concentration of the surfactant in the polishing composition S1 can be, for example, 0.0006% by mass or more, relative to the total mass of the polishing composition S1. Furthermore, the concentration of the surfactant in the polishing composition S1 is not particularly limited, but is preferably 1% by mass or less, more preferably 0.01% by mass or less, even more preferably 0.001% by mass or less, and particularly preferably 0.0008% by mass or less, relative to the total mass of the polishing composition S1. Within these ranges, the removal rate is further improved. Examples of preferred surfactant concentrations in the polishing composition S1 include, but are not limited to, 0.0001% by mass or more and 1% by mass or less, 0.0002% by mass or more and 0.01% by mass or less, 0.0004% by mass or more and 0.001% by mass or less, and 0.0004% by mass or more and 0.0008% by mass or less, relative to the total mass of the polishing composition S1.

[0110] The concentration of the surfactant in the polishing composition S2 is not particularly limited, but is preferably 0.0001% by mass or more, more preferably 0.0002% by mass or more, and even more preferably 0.0004% by mass or more, relative to the total mass of the polishing composition S2. Within these ranges, surface defects occurring on the polished surface of the substrate are further reduced. Furthermore, the concentration of the surfactant in the polishing composition S2 can be, for example, 0.0006% by mass or more, relative to the total mass of the polishing composition S2. Furthermore, the concentration of the surfactant in the polishing composition S2 is not particularly limited, but is preferably 1% by mass or less, more preferably 0.01% by mass or less, even more preferably 0.001% by mass or less, and particularly preferably 0.0008% by mass or less, relative to the total mass of the polishing composition S2. Within these ranges, the removal rate is further improved. Examples of preferred surfactant concentrations in the polishing composition S2 include, but are not limited to, 0.0001% by mass or more and 1% by mass or less, 0.0002% by mass or more and 0.01% by mass or less, 0.0004% by mass or more and 0.001% by mass or less, and 0.0006% by mass or more and 0.0008% by mass or less, relative to the total mass of the polishing composition S2.

[0111] (dispersion medium) Polishing Composition S1 and Polishing Composition S2 contain water as a dispersion medium, which functions to disperse or dissolve each component.

[0112] The content of water in the dispersion medium is not particularly limited, but is preferably 50% by mass or more, more preferably 90% by mass or more, based on the total mass of the dispersion medium, and even more preferably water alone. The water is preferably water that contains as few impurities as possible, from the viewpoint of preventing contamination of the object to be polished and inhibiting the action of other components. For example, water with a total transition metal ion content of 100 ppb by mass or less is preferred. The purity of the water can be increased by, for example, removing impurity ions using an ion exchange resin, removing foreign matter using a filter, or by distillation. Specifically, the water used may be, for example, deionized water (ion-exchanged water), pure water, ultrapure water, or distilled water.

[0113] Polishing composition S1 and polishing composition S2 may each contain an organic solvent in addition to water as a dispersion medium, if it can improve the dispersibility or solubility of each component.The organic solvent is not particularly limited, and known organic solvents can be used.In addition, the organic solvent may be used alone, or two or more kinds may be used in combination.

[0114] (Other ingredients) The polishing composition S1 and the polishing composition S2 may each independently contain other components other than the above-listed components, as long as the effects of the present invention are not impaired.The other components are not particularly limited, and include known components that can be used in polishing compositions and rinse polishing compositions.Specific examples are not particularly limited, and include, but are not limited to, acids, chelating agents, preservatives, antifungal agents, dissolved gases, reducing agents, etc.

[0115] (Method of manufacturing polishing composition) The method for producing polishing composition S1 is not particularly limited, as long as it includes mixing abrasive grains 1, a water-soluble polymer having an abrasive adsorption parameter of 5 or more, water, and other components that are added as needed. The method for producing polishing composition S2 is not particularly limited, as long as it includes mixing abrasive grains 2, a water-soluble polymer having an abrasive adsorption parameter of less than 5, water, and other components that are added as needed.

[0116] The mixing method for mixing the components is not particularly limited, and known methods can be used as appropriate. The mixing temperature is not particularly limited, but is generally preferably 10°C or higher and 40°C or lower, and heating may be used to increase the dissolution rate. The mixing time is also not particularly limited.

[0117] [Polished object] In the polishing method according to one embodiment of the present invention, the substrate to be polished is not particularly limited, but is preferably a semiconductor substrate. Therefore, another aspect of the present invention can be said to relate to a method for manufacturing a semiconductor substrate, which includes polishing a substrate using the above-mentioned polishing method. Examples of the substrate include a substrate composed of a single layer and a substrate including a layer to be polished and other layers (e.g., a support layer or other functional layers).

[0118] In a polishing method according to one embodiment of the present invention, the substrate to be polished preferably contains, but is not limited to, a material having silicon-silicon bonds. Examples of materials having silicon-silicon bonds include, but are not limited to, polysilicon, amorphous silicon, single crystal silicon, n-type doped single crystal silicon, p-type doped single crystal silicon, and Si-based alloys such as SiGe. Among these, single crystal silicon, n-type doped single crystal silicon, or p-type doped single crystal silicon is preferred, with p-type doped single crystal silicon being more preferred, from the viewpoint of achieving the effects of the present invention more significantly. These materials having silicon-silicon bonds can be used alone or in combination of two or more.

[0119] For these reasons, the substrate is preferably a silicon substrate (silicon wafer).

[0120] <Polishing composition set> Another aspect of the present invention is A polishing composition set for use in a method for polishing a substrate, comprising: The polishing method includes a polishing step, The polishing step includes two or more polishing stages in which the substrate is polished by rotating the polishing platen while supplying a polishing composition to a contact surface between the substrate and a polishing pad attached to the polishing platen, The two or more polishing stages include: a polishing stage 1 for polishing on a polishing table; A polishing stage 2 that polishes the substrate on the same polishing table as the polishing stage 1 after the polishing stage 1, The polishing composition set includes: a polishing composition S1 used in the polishing stage 1, which contains abrasive grains 1, water, and a water-soluble polymer having an abrasive grain adsorption parameter of 5 or more calculated by the following procedures (1) to (4); a polishing composition S2 used in the polishing stage 2, which contains abrasive grains 2, water, and a water-soluble polymer having an abrasive adsorption parameter of less than 5, and does not contain a water-soluble polymer having an abrasive adsorption parameter of 5 or more in an amount of 0.005 mass% or more (i.e., the concentration of the water-soluble polymer having an abrasive adsorption parameter of 5 or more in the polishing composition S2 is less than 0.005 mass% relative to the total mass of the polishing composition S2); a polishing composition set comprising: (1) Prepare a test solution L containing 0.08% by mass of colloidal silica having an average primary particle size of 25 nm and an average secondary particle size of 50 nm, 0.004% by mass of a water-soluble polymer to be measured, and 0.005% by mass of ammonia, with the remainder being water. (2) The total organic carbon concentration (TOC value) of the test liquid L is measured, and the obtained TOC value is defined as the total organic carbon concentration W0 [ppm by mass] of the water-soluble polymer to be measured contained in the test liquid L. (3) The test liquid L is centrifuged at 26,000 rpm for 30 minutes to separate it into a sediment and a supernatant, and the TOC value of the supernatant is measured. The obtained TOC value is defined as the total organic carbon concentration W1 [ppm by mass] of the water-soluble polymer to be measured contained in the supernatant. (4) The adsorption ratio of the water-soluble polymer to be measured is calculated using the following formula, and this value is used as the abrasive adsorption parameter.

[0121]

number

[0122] According to this aspect, it is possible to provide a means for reducing surface defects on a substrate after polishing.

[0123] The details of the polishing method are as described above. The details of the polishing step, other steps, polishing composition S1, polishing composition S2, and object to be polished are also as described above.

[0124] It is preferable that polishing composition S1 is a finish polishing composition, and polishing composition S2 is a rinse polishing composition.

[0125] The polishing composition set may further contain one or more other polishing compositions as needed in addition to polishing composition S1 and polishing composition S2. In this case, it is preferable that polishing composition S1 is a finish polishing composition, polishing composition S2 is a rinse polishing composition, and the other polishing compositions are pre-polishing compositions or finish polishing compositions. It is more preferable that polishing composition S1 is a finish polishing composition, polishing composition S2 is a rinse polishing composition, and the other polishing compositions are pre-polishing compositions.

[0126] Furthermore, each polishing composition included in the polishing composition set may be in a concentrated form. A concentrated form refers to the form of a concentrated polishing composition, which can also be understood as a stock solution of the polishing composition. The concentration ratio is not particularly limited, and can be, for example, about 2 to 100 times in volume, and is usually about 5 to 50 times, for example, about 10 to 40 times. Such a concentrated solution can be diluted at a desired time to prepare a polishing composition, and the polishing composition can be supplied to the object to be polished. Dilution can be performed, for example, by adding water to the concentrated solution and mixing. [Example]

[0127] 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 "% by mass" and "parts by mass", respectively.

[0128] <Polishing composition> [Preparation of Polishing Composition] The following materials were mixed in deionized water (DIW) to prepare polishing compositions having the compositions shown in Tables 2 to 5 below.

[0129] Abrasive grain Silica A: Colloidal silica, average primary particle size by BET method: 35 nm, average secondary particle size by dynamic light scattering method: 70 nm, Silica B: Colloidal silica, average primary particle size by BET method: 25 nm, average secondary particle size by dynamic light scattering method: 50 nm, Silica C: Colloidal silica, average primary particle size by BET method: 15 nm, average secondary particle size by dynamic light scattering method: 35 nm.

[0130] ·Water-soluble polymer PVA: Polyvinyl alcohol (weight average molecular weight: 70,000, saponification degree 98 mol% or more), Ac-PVA: acetalized polyvinyl alcohol (weight average molecular weight: 13,000, type of acetalization: polyvinyl ethylal, degree of acetalization: 30 mol%) Ac-PVA (2): acetalized polyvinyl alcohol (weight average molecular weight: 9,700, type of acetalization: polyvinyl ethylal, degree of acetalization: 24 mol%), HEC: Hydroxyethyl cellulose (weight average molecular weight: 250,000), PACMO: poly N-acryloylmorpholine (weight average molecular weight: 350,000).

[0131] Basic compounds NH3: Ammonia water (concentration 29 mass%, values ​​shown in Tables 2 and 4 below are converted into the amount of ammonia), triethylamine, trimethylamine, diethylamine, ethylamine, Triethanolamine.

[0132] Surfactants C10EO5: Polyoxyethylene decyl ether (C 10 H 21 O(CH2CH2O)5H, molecular weight: 378).

[0133] [Weight average molecular weight] The weight average molecular weight of the water-soluble polymer was measured by GPC under the following conditions.

[0134] ≪Weight average molecular weight measurement conditions≫ Evaluation equipment: HLC-8320GPC (Tosoh Corporation) Sample concentration: 0.1% by mass Column: TSKgel GMPWXL Detector: differential refractometer Eluent: 100mM sodium nitrate aqueous solution Flow rate: 1mL / min Measurement temperature: 40℃ Sample injection volume: 200 μL (Polyoxyethylene equivalent).

[0135] [Abrasive adhesion parameters] The abrasive adsorption parameters of the water-soluble polymer were calculated according to the following procedures (1) to (4).

[0136] <Adsorption parameter evaluation conditions> (1) A test solution L was prepared containing 0.08% by mass of colloidal silica (PL-2 manufactured by Fuso Chemical Co., Ltd., average primary particle size 25 nm, average secondary particle size 50 nm), 0.004% by mass of the water-soluble polymer to be measured, and 0.005% by mass of ammonia, with the remainder being water. (2) The total organic carbon concentration (TOC value) of the test liquid L was measured, and the obtained TOC value was defined as the total organic carbon concentration W0 [ppm by mass] of the water-soluble polymer to be measured contained in the test liquid L. (3) The test liquid L was centrifuged at 26,000 rpm for 30 minutes using an Avanti HP-30I manufactured by Beckman Coulter, Inc. to separate it into a sediment and a supernatant, and the TOC value of the supernatant was measured. The obtained TOC value was defined as the total organic carbon concentration W1 [ppm by mass] of the water-soluble polymer to be measured contained in the supernatant. (4) The adsorption ratio of the water-soluble polymer to be measured was calculated using the following formula, and this value was used as the abrasive adsorption parameter.

[0137]

number

[0138] Here, the total organic carbon concentration W0 [ppm by mass] of the water-soluble polymer to be measured contained in the test liquid L and the total organic carbon concentration W1 [ppm by mass] of the water-soluble polymer to be measured contained in the supernatant after centrifugal separation of the test liquid L were evaluated using a total organic carbon meter TOC-L manufactured by Shimadzu Corporation.

[0139] The values ​​of the abrasive adsorption parameters are shown in the following Tables 2 to 5. In Tables 2 to 5, a water-soluble polymer having an abrasive adsorption parameter of less than 5 is referred to as "water-soluble polymer X," and a water-soluble polymer having an abrasive adsorption parameter of 5 or more is referred to as "water-soluble polymer Y."

[0140] <Polishing method> Silicon wafers were polished by a polishing method including a polishing process including each polishing stage listed in Table 1. The polishing conditions at each polishing stage in the polishing methods according to the examples and comparative examples are shown below.

[0141] In addition, for each polishing method according to the examples and comparative examples, the polishing compositions obtained above were used as the finish polishing composition used in the finish polishing stage and the rinse polishing composition used in the rinse polishing stage. The compositions of the polishing compositions are shown in Tables 2 to 5 below.

[0142] [Pre-polishing stage] Single crystal silicon wafer (diameter: 300 mm, p-type, crystal orientation <100> , COP-free) was polished on one side on polishing platen 1 of the polishing apparatus described below under the polishing conditions described below using the pre-polishing composition described below.

[0143] ≪Pre-polishing composition≫ Pre-polishing composition: A polishing composition was obtained by mixing deionized water (DIW) as a dispersion medium with 0.6 mass% colloidal silica (abrasive grains, average primary particle diameter by BET method 35 nm, average secondary particle diameter by dynamic light scattering method 70 nm), 0.08 mass% TMAH (tetramethylammonium hydroxide), and 0.0002 mass% HEC (hydroxyethyl cellulose, weight average molecular weight 1.2 million) relative to the total mass of the polishing composition.

[0144] <Polishing conditions in the pre-polishing stage> Polishing equipment: Okamoto Machine Tool Works, Ltd., sheet-fed polishing machine, model "PNX 332B" Polishing load: 20kPa Plate rotation speed: 20 rpm Template rotation speed: 20 rpm Polishing pad: Fujibo Ehime Co., Ltd. Product name "FP55" Polishing composition supply rate: 1 L / min Temperature of polishing composition: 20°C Temperature of surface plate cooling water: 20℃.

[0145] [Finishing Polishing Stage (Polishing Stage 1 of the Present Invention)] Next, the single crystal silicon wafer polished in the above-mentioned pre-polishing stage was subjected to one-side polishing using the finish polishing composition shown in Table 2 and Table 3 below, by the same polishing apparatus as in the above-mentioned pre-polishing stage, on a polishing platen 2 different from the polishing platen 1, under the polishing conditions shown below.

[0146] <Polishing conditions in the final polishing stage> Polishing equipment: Okamoto Machine Tool Works, Ltd., sheet-fed polishing machine, model "PNX 332B" Polishing load: 20kPa Plate rotation speed: 52 rpm Template rotation speed: 50 rpm Polishing pad: POLYPAS (registered trademark) 275NX, manufactured by Fujibo Ehime Co., Ltd. Polishing fluid supply rate: 1.5L / min Polishing solution temperature: 20℃ Temperature of surface plate cooling water: 20℃.

[0147] [Rinse polishing stage (polishing stage 2 according to the present invention)] Then, the single crystal silicon wafer polished in the above-mentioned finish polishing stage was subjected to one-side polishing using the rinse polishing composition shown in Table 4 and Table 5 below, by the same polishing apparatus as in the pre-polishing stage and the finish polishing stage, on the same polishing platen 2 as in the finish polishing stage, and under polishing conditions similar to those in the finish polishing stage.

[0148] [Cleaning] A first cleaning tank containing a cleaning solution of NH4OH (29 mass%): HO2 (31 mass%): deionized water (DIW) = 2:5.3:48 (volume ratio) maintained at 70°C, and a second cleaning tank containing ultrapure water at 25°C were prepared. The single crystal silicon wafer polished in the above rinse-polishing stage was then immersed in the first cleaning tank for 6 minutes, then immersed in the second cleaning tank for 15 minutes with the ultrasonic oscillator operating, then immersed in the first cleaning tank again for 6 minutes, and then immersed in the second cleaning tank for 16 minutes with the ultrasonic oscillator operating, and then dried. This yielded polished silicon wafers.

[0149] [Table 1]

[0150] [Table 2]

[0151] [Table 3]

[0152] [Table 4]

[0153] [Table 5]

[0154] <Evaluation> [Number of defects on polished silicon wafers] The number of defects (pieces) on the polished silicon wafers obtained above was first evaluated in measurement mode: DC mode using an optical inspection machine (wafer inspection device) "SURFSCAN SP5" manufactured by KLA-TENCOR Corporation. The results are shown in Table 6 below as a percentage (%) of the number of defects (pieces) in Comparative Example 2, with the number of defects (pieces) in Comparative Example 2 set as 100%.

[0155] [Table 6]

[0156] From the results in Tables 1 to 6 above, it was confirmed that the substrates polished by the polishing methods of Examples 1 to 10 according to the present invention had significantly fewer defects. On the other hand, it was confirmed that the substrates polished by the polishing methods of Comparative Examples 1 to 4, which are outside the scope of the present invention, had significantly more defects than the substrates polished by the polishing methods of Examples 1 to 10 according to the present invention.

[0157] This application is based on Japanese Patent Application No. 2021-052791, filed on March 26, 2021, the disclosure of which is incorporated by reference in its entirety.

Claims

1. A method for polishing a substrate, comprising: The polishing method includes a polishing step, The polishing step includes two or more polishing stages in which the substrate is polished by rotating the polishing platen while supplying a polishing composition to a contact surface between the substrate and a polishing pad attached to the polishing platen, The two or more polishing stages include: a polishing stage 1 in which polishing is performed on a polishing platen using a polishing composition S1; After the polishing stage 1, a polishing stage 2 is performed using a polishing composition S2 on the same polishing platen as the polishing stage 1; The polishing composition S1 contains abrasive grains 1, water, and a water-soluble polymer having an abrasive adsorption parameter of 5 or more calculated by the following procedures (1) to (4): The polishing composition S2 contains abrasive grains 2, water, and a water-soluble polymer having an abrasive adsorption parameter of less than 5, and does not contain a water-soluble polymer having an abrasive adsorption parameter of 5 or more in an amount of 0.005 mass% or more. Polishing method: (1) Prepare a test solution L containing 0.08% by mass of colloidal silica having an average primary particle size of 25 nm and an average secondary particle size of 50 nm, 0.004% by mass of a water-soluble polymer to be measured, and 0.005% by mass of ammonia, with the remainder being water. (2) The total organic carbon concentration (TOC value) of the test liquid L is measured, and the obtained TOC value is used as the total organic carbon concentration W of the water-soluble polymer to be measured contained in the test liquid L. ０ Let's say, (3) The test liquid L is centrifuged at 26,000 rpm for 30 minutes to separate it into a sediment and a supernatant, and the TOC value of the supernatant is measured. The TOC value is then used as the total organic carbon concentration W of the water-soluble polymer to be measured contained in the supernatant. １ Let's say, (4) The adsorption ratio of the water-soluble polymer to be measured is calculated using the following formula, and this value is used as the abrasive adsorption parameter. [Equation 1]

2. The concentration of the abrasive grains 1 in the polishing composition S1 is 0.001 mass% or more and 3 mass% or less, based on the total mass of the polishing composition S1; The concentration of the abrasive grains 2 in the polishing composition S2 is 0.001 mass% or more and 3 mass% or less, based on the total mass of the polishing composition S2. The polishing method according to claim 1 .

3. 3. The polishing method according to claim 1, wherein the concentration of the abrasive grains 2 in the polishing composition S2 is equal to or lower than the concentration of the abrasive grains 1 in the polishing composition S1.

4. 4. The polishing method according to claim 1, wherein the average primary particle size of the second abrasive grains is equal to or smaller than the average primary particle size of the first abrasive grains.

5. 5. The polishing method according to claim 1, wherein the first abrasive grain and the second abrasive grain are silica.

6. The concentration of the water-soluble polymer in the polishing composition S1 is 0.0001 mass% or more and 2 mass% or less, based on the total mass of the polishing composition S1, The concentration of the water-soluble polymer in the polishing composition S2 is 0.0001% by mass or more and 1% by mass or less, based on the total mass of the polishing composition S2. The polishing method according to any one of claims 1 to 5.

7. 7. The polishing method according to claim 1, wherein the concentration of the water-soluble polymer in said polishing composition S2 is equal to or lower than the concentration of the water-soluble polymer in said polishing composition S1.

8. the water-soluble polymer having an abrasive adsorption parameter of 5 or more is at least one polymer selected from the group consisting of cellulose derivatives, polymers having a partial structure containing a nitrogen atom in the molecule, and polymers having two or more hydroxy groups in the molecule and having an unsubstituted polyoxyalkylene structure; The polishing method according to any one of claims 1 to 7, wherein the water-soluble polymer having an abrasive adsorption parameter of less than 5 is at least one polymer selected from the group consisting of a polymer containing two or more hydroxy groups in its molecule and containing a substituted polyoxyalkylene structure, a polymer containing two or more hydroxy groups in its molecule and containing a structural unit derived from vinyl alcohol, and a polymer containing an anionic group in its molecule.

9. 9. The polishing method according to claim 1, wherein the polishing composition S1 and the polishing composition S2 further contain a basic compound.

10. 10. The polishing method according to claim 1, wherein the polishing composition S1 and the polishing composition S2 further contain a surfactant.

11. The polishing method according to any one of claims 1 to 10, wherein the polishing time in the second polishing stage is shorter than the polishing time in the first polishing stage.

12. 12. The polishing method according to claim 1, wherein the substrate is a silicon wafer.

13. A method for manufacturing a semiconductor substrate, comprising polishing the substrate with the polishing method according to any one of claims 1 to 12.

14. A polishing composition set for use in a method for polishing a substrate, comprising: The polishing method includes a polishing step, The polishing step includes two or more polishing stages in which the substrate is polished by rotating the polishing platen while supplying a polishing composition to a contact surface between the substrate and a polishing pad attached to the polishing platen, The two or more polishing stages include: a polishing stage 1 for polishing on a polishing table; a polishing stage 2 that performs polishing on the same polishing table as the polishing stage 1 after the polishing stage 1; The polishing composition set includes: a polishing composition S1 used in the polishing stage 1, which contains abrasive grains 1, water, and a water-soluble polymer having an abrasive grain adsorption parameter of 5 or more calculated by the following procedures (1) to (4); a polishing composition S2 used in the polishing stage 2, which contains abrasive grains 2, water, and a water-soluble polymer having an abrasive grain adsorption parameter of less than 5, and does not contain a water-soluble polymer having an abrasive grain adsorption parameter of 5 or more in an amount of 0.005 mass% or more; A polishing composition set comprising: (1) Prepare a test solution L containing 0.08% by mass of colloidal silica having an average primary particle size of 25 nm and an average secondary particle size of 50 nm, 0.004% by mass of a water-soluble polymer to be measured, and 0.005% by mass of ammonia, with the remainder being water. (2) The total organic carbon concentration (TOC value) of the test liquid L is measured, and the obtained TOC value is used as the total organic carbon concentration W of the water-soluble polymer to be measured contained in the test liquid L. ０ Let's say, (3) The test liquid L is centrifuged at 26,000 rpm for 30 minutes to separate it into a sediment and a supernatant, and the TOC value of the supernatant is measured. The TOC value is then used as the total organic carbon concentration W of the water-soluble polymer to be measured contained in the supernatant. １ Let's say, (4) The adsorption ratio of the water-soluble polymer to be measured is calculated using the following formula, and this value is used as the abrasive adsorption parameter. [Equation 2]

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