JP7104053B2 - Polishing composition and silicon substrate polishing method - Google Patents

Description

The present invention relates to a polishing composition and a method for polishing a silicon substrate. This application claims priority under Japanese Patent Application No. 2017-172557 filed on September 7, 2017, the entire contents of which are incorporated herein by reference.

Polishing is performed on the surface of materials such as metals, metalloids, non-metals, and oxides thereof using a polishing composition containing abrasive grains. For example, with respect to a silicon substrate used for manufacturing a semiconductor element or the like, various studies have been conducted on a polishing technique for obtaining a high-quality mirror surface that is highly flat and free from scratches and impurities. Generally, a silicon substrate is finished into a high-quality mirror surface through a wrapping process and a polishing process. The polishing step usually includes a pre-polishing step and a finish polishing step. The silicon substrate polished with the polishing composition (composition for finish polishing) used in the finish polishing step is then washed to remove deposits and the like derived from the above polishing composition to obtain a clean surface. Will be done. In Patent Document 1, a semiconductor wafer such as a silicon wafer is washed with a mixed cleaning solution of ammonia water, hydrogen peroxide solution, and water (hereinafter referred to as SC-1 cleaning solution), then with hydrofluoric acid, and further with ozone. A technique for efficiently cleaning a wafer while reducing deterioration of surface roughness due to cleaning by cleaning with water is described.

Japanese Patent Application Publication No. 2012-129409

By the way, when the surface of a silicon substrate that has been mirror-finished by polishing is irradiated with strong light, cloudiness may be observed due to diffused reflection caused by extremely fine roughness of the surface. This haze is called haze, and haze is used as a measure of the surface roughness of a silicon substrate. If there is a haze on the surface of the silicon wafer, the diffusely reflected light generated by the haze may become noise and hinder the defect detection by the surface defect inspection device. Therefore, as the size of the defect to be detected, that is, the size of the defect to be managed becomes smaller, the need for improving the haze level increases.

Incorporating a water-soluble polymer into the polishing composition used for finish polishing can be an effective means for lowering the surface roughness that can be reached by polishing. On the other hand, if the residue of the water-soluble polymer is present on the surface of the silicon substrate after polishing, it can be detected as particles in the surface inspection of the substrate and can be a factor of increasing defects called LPD (Light Point Defects). However, as shown in the results of the comparative examples shown in FIGS. Is improved and LPD is reduced, but the surface roughness tends to be deteriorated. Further, when the treatment intensity is weakened, the deterioration of the surface roughness due to the treatment (etching) with the SC-1 cleaning liquid is suppressed, but the removability of particles tends to decrease and the LPD tends to increase.

Therefore, an object of the present invention is to provide a polishing composition capable of simultaneously achieving low LPD and low surface roughness. Another relevant object is to provide a method of polishing a silicon substrate with such a polishing composition.

The polishing composition provided herein comprises abrasive grains, a basic compound, a water-soluble polymer, and a surfactant. The water-soluble polymer has the following formula (I):
α = θ1-θ0 (I);
Includes a water-soluble polymer WP in which the detergency parameter α represented by is in the range of 1 <α <35. Here, θ0 in the above formula (I) is the water contact angle of the SC-1 untreated wafer obtained by applying the aqueous solution of the water-soluble polymer on the surface of the single crystal silicon wafer and then washing with water. Θ1 in the above formula (I) is a room temperature SC-1 cleaning liquid L in which 29% ammonia water, 31% hydrogen peroxide water and water are contained in the SC-1 untreated wafer at a volume ratio of 1: 2:30. This is the water contact angle of the SC-1 treated wafer obtained by performing the cleaning treatment A which is treated with _A for 10 seconds. In this specification, the contact angle is expressed in the unit of "degree (°)". Further, in the present specification, the concentration and the content shall be expressed on a weight basis unless otherwise specified.

The detergency parameter α of less than 35 is advantageous from the viewpoint of reducing the surface roughness by polishing. Further, when the detergency parameter α is larger than 1, the LPD of the surface after polishing can be efficiently reduced even by cleaning under the condition that the deterioration of the surface roughness is suppressed. As a result, according to the above-mentioned polishing composition, both low LPD and low surface roughness can be suitably compatible.

Further, according to this specification, a step A of polishing the surface of a silicon wafer using any of the polishing compositions disclosed herein, and a step B of treating the silicon wafer with an SC-1 cleaning liquid are performed. A silicon wafer polishing method including this order is provided. The process of the above step B is performed by the following formula (II):
β [%] = H ₁ / H ₀ × 100 (II);
It is performed under the condition set so that the cleaning load parameter β represented by is 80% or less. Here, H ₀ in the above formula (II) is a volume ratio of 29% ammonia water, 31% hydrogen peroxide solution, and water to the silicon wafer obtained in the above step A at a volume ratio of 1: 3:30. It represents the haze value [ppm] of the surface obtained by performing the cleaning treatment B which is treated with the SC-1 cleaning liquid L ₀ at 60 ° C. for 12 minutes. H1 in the above formula (II) represents a surface haze value [ppm] obtained by processing the silicon wafer obtained in the above step _A by the above step B.

In the above step A, the polishing composition disclosed herein, that is, a polishing composition capable of efficiently reducing the LPD of the surface after polishing even by cleaning under conditions suitable for suppressing deterioration of surface roughness is used. Polish the silicon wafer. Therefore, the LPD can be effectively reduced by the cleaning treatment under the condition of lower cleaning load, specifically, the cleaning treatment under the condition that the cleaning load parameter β is 80% or less. Therefore, according to the above manufacturing method, a silicon substrate having a low surface roughness and a reduced LPD can be preferably manufactured.

Hereinafter, preferred embodiments of the present invention will be described. Matters other than those specifically mentioned in the present specification and necessary for carrying out the present invention can be grasped as design matters of those skilled in the art based on the prior art in the art. The present invention can be carried out based on the contents disclosed in the present specification and the common general technical knowledge in the art.

<Abrasive grains>
The polishing composition disclosed herein contains abrasive grains. Abrasive grains serve to mechanically polish the surface of the object to be polished.

The material and properties of the abrasive grains are not particularly limited, and can be appropriately selected depending on the purpose and mode of use of the polishing composition. Examples of abrasive grains include inorganic particles, organic particles, and organic-inorganic composite particles. Specific examples of the inorganic particles include oxide particles such as silica particles, alumina particles, cerium oxide particles, chromium oxide particles, titanium dioxide particles, zirconium oxide particles, magnesium oxide particles, manganese dioxide particles, zinc oxide particles, and red iron oxide particles; Nitride particles such as silicon nitride particles and boron nitride particles; carbide particles such as silicon carbide particles and boron carbide particles; diamond particles; carbonates such as calcium carbonate and barium carbonate can be mentioned. Specific examples of the organic particles include polymethylmethacrylate (PMMA) particles, poly (meth) acrylic acid particles, polyacrylonitrile particles, and the like. Such abrasive grains may be used alone or in combination of two or more. In addition, in this specification, (meth) acrylic has a meaning which comprehensively refers to acrylic and methacrylic. Similarly, as used herein, (meth) acryloyl is meant to collectively refer to acryloyl and methacryloyl.

As the abrasive grains, inorganic particles are preferable, particles made of metal or metalloid oxides are preferable, and silica particles are particularly preferable. In a polishing composition that can be used for polishing an object to be polished having a surface made of silicon such as a silicon substrate, for example, finish polishing, it is particularly meaningful to use silica particles as abrasive grains. The technique disclosed herein can be preferably carried out in a manner in which the abrasive grains are substantially composed of silica particles. Here, "substantially" means that 95% by weight or more, preferably 98% by weight or more, more preferably 99% by weight or more of the particles constituting the abrasive grains are silica particles, and 100% by weight is silica. It means that it is a particle.

Specific examples of the silica particles include colloidal silica, fumed silica, precipitated silica and the like. The silica particles may be used alone or in combination of two or more. The use of colloidal silica is particularly preferable because it is easy to obtain a polished surface having excellent surface quality after polishing. As the colloidal silica, for example, colloidal silica prepared from water glass (Na silicate) by an ion exchange method or alkoxide method colloidal silica can be preferably adopted. The alkoxide method colloidal silica refers to colloidal silica produced by a hydrolysis condensation reaction of alkoxysilane. Colloidal silica can be used alone or in combination of two or more.

The true specific gravity of the abrasive grain constituent material is preferably 1.5 or more, more preferably 1.6 or more, and may be 1.7 or more. Here, the true specific gravity of the abrasive grain constituent material means, for example, in the case of abrasive grains made of silica particles, the true specific gravity of the silica constituting the silica particles. Hereinafter, it is also referred to as the true specific density of the abrasive grains. As the true specific gravity of the abrasive grains increases, the physical polishing ability of the abrasive grains tends to increase. The upper limit of the true specific gravity of the abrasive grains is not particularly limited, but is typically 2.3 or less, for example 2.2 or less. As the true specific gravity of the abrasive grains, a measured value by a liquid replacement method using ethanol as a replacement liquid can be adopted. The abrasive grains can be, for example, silica particles.

The BET diameter of the abrasive grains is not particularly limited, but is preferably 5 nm or more, more preferably 10 nm or more from the viewpoint of polishing efficiency and the like. From the viewpoint of obtaining a higher polishing effect, for example, from the viewpoint of better exhibiting effects such as haze reduction and defect removal, the BET diameter is preferably, for example, 15 nm or more, more preferably 20 nm or more, and more preferably more than 20 nm. .. Further, from the viewpoint of suppressing local stress applied to the surface of the object to be polished by the abrasive grains, the BET diameter of the abrasive grains is preferably 100 nm or less, more preferably 50 nm or less, still more preferably 40 nm or less. The techniques disclosed herein have a BET diameter of 35 nm or less, preferably less than 35 nm, more preferably 32 nm or less, for example less than 30 nm, from the viewpoint of facilitating the acquisition of a higher quality surface, for example, a low LPD and low haze surface. It may be carried out in the embodiment using the abrasive grains of. The abrasive grains can be, for example, silica particles. Abrasive particles made of silica particles are particularly preferable.

In the present specification, the BET diameter is defined as the BET diameter [nm] = 6000 / (true density [g / cm ³ ] × BET value [m ² / g) from the specific surface area (BET value) measured by the BET method. ]) Refers to the particle size calculated by the formula. For example, in the case of silica particles, the BET diameter can be calculated from the BET diameter [nm] = 2727 / BET value [m ² / g]. The specific surface area can be measured, for example, by using a surface area measuring device manufactured by Micromeritex Co., Ltd., trade name "Flow Sorb II 2300".

The shape (outer shape) of the abrasive grains may be spherical or non-spherical. Specific examples of the non-spherical particles include a peanut shape, a cocoon shape, a konpeito shape, a rugby ball shape, and the like. The peanut shape is, that is, the shape of a peanut shell. For example, abrasive grains in which many of the particles are peanut-shaped or cocoon-shaped can be preferably adopted.

Although not particularly limited, the average aspect ratio of the abrasive grains, that is, the average value of the major axis / minor axis ratio of the abrasive grains is, in principle, 1.0 or more, preferably 1.05 or more, and more preferably 1. .1 or more. Higher polishing efficiency can be achieved by increasing the average aspect ratio. The average aspect ratio of the abrasive grains is preferably 3.0 or less, more preferably 2.0 or less, still more preferably 1.5 or less, from the viewpoint of scratch reduction and the like.

The shape (outer shape) and average aspect ratio of the abrasive grains can be grasped by, for example, observing with an electron microscope. As a specific procedure for grasping the average aspect ratio, for example, using a scanning electron microscope (SEM), for a predetermined number of silica particles capable of recognizing the shape of independent particles, the minimum circumscribing to each particle image. Draw a rectangle. The predetermined number is, for example, 200. Then, for the rectangle drawn for each particle image, the length of the long side is the value of the major axis, the length of the short side is the value of the minor axis, and the value of the major axis is divided by the value of the minor axis. Is calculated as the major axis / minor axis ratio of each abrasive grain, that is, the aspect ratio. The average aspect ratio can be obtained by arithmetically averaging the aspect ratios of the predetermined number of particles.

<Water-soluble polymer>
The polishing composition disclosed herein contains a water-soluble polymer as an essential component. The water-soluble polymer can contribute to the reduction of haze by protecting the surface of the object to be polished. In addition, in this specification, a "water-soluble polymer" means a polymer having a solubility in water at 25 ° C. of 0.01 g / 100 mL or more.

The polishing composition disclosed herein contains, as the water-soluble polymer, at least a water-soluble polymer WP having a detergency parameter α in the range of 1 <α <35. The cleanability parameter α is the water contact angle θ0 on the surface of the silicon wafer on which the water-soluble polymer to be measured is adsorbed, and the water on the surface after treating the silicon wafer with the SC _- 1 cleaning liquid LA for 10 seconds at room temperature. It is obtained as the difference from the contact angle θ1. More specifically, the detergency parameter α is measured by the following method.

[Measurement method of detergency parameter α]
(1) A wafer chip (hereinafter, also referred to as a test piece) obtained by cutting a commercially available mirror-surfaced silicon wafer into a 6 cm square is first treated with an SC-1 cleaning solution, and then with a 2.5% hydrogen fluoride (HF) aqueous solution. Pretreatment is performed to remove the surface oxide film by treatment. As the test piece, a single crystal silicon wafer having a conduction type of P type, a crystal orientation of <100>, and a resistivity of 0.1 Ω · cm or more and less than 100 Ω · cm is used.
(2) Prepare an aqueous solution LP containing the water _- soluble polymer to be measured at a concentration of 0.18% and adjusted to pH 10 with ammonia. 60 g of the aqueous solution LP is supplied to the test piece, a load of 1 kg is applied, and the aqueous solution _LP is rubbed against the surface of the test piece with a polyester / cellulose non _- woven fabric. After supplying the test piece with the aqueous solution LP and rubbing it for 1 minute, the test piece is immersed in deionized water to remove excess water _- soluble polymer.
(3) By treating the test piece with a 2.5% HF aqueous solution, the surface oxide film formed in the step (2) above is removed.
(4) The water contact angle θ0 of the test piece (wafer before SC-1 treatment) is measured.
(5) _A cleaning treatment in which the above test piece is treated with SC-1 cleaning solution LA at room temperature containing 29% ammonia water, 31% hydrogen peroxide solution and water at a volume ratio of 1: 2:30 for 10 seconds. Do A. Next, the test piece is immersed in deionized water and further treated with a 2.5% HF aqueous solution.
(6) The water contact angle θ1 of the test piece (wafer after SC-1 treatment) is measured.
(7) From θ0 and θ1 thus obtained, the detergency parameter α is calculated by the formula α = θ1-θ0.

In the step (1), in the treatment with the SC-1 cleaning solution, 29% ammonia water, 31% hydrogen peroxide water, and deionized water are usually mixed at a volume ratio of 1: 2:30. The SC-1 cleaning solution can be suitably carried out by accommodating the SC-1 cleaning solution in a cleaning tank and immersing the test piece in the cleaning solution at room temperature. However, the above processing conditions can be appropriately changed according to the initial state of the test piece to be used and the like so that the measurements of θ0 and θ1 can be appropriately performed.

Further, in the step (5), the cleaning treatment _A is performed by accommodating the SC-1 cleaning liquid LA in a 100 mL cleaning tank and immersing the test piece at room temperature for 10 seconds. At the time of the above immersion, ultrasonic waves are not applied. The test piece after the above treatment for 10 seconds is immediately immersed in 100 mL of deionized water.

Further, in the steps (4) and (6) above, the water contact angle was measured by dropping 2.1 μL of deionized water onto the surface of the test piece at a measurement temperature of 25 ° C., taking a photograph, and taking a photograph of θ /. This is done by determining the contact angle using the two methods. The measurement time shall be less than 1 second after the water droplets are allowed to stand on the test piece. As the contact angle measuring device, CA-X200 manufactured by Kyowa Interface Science Co., Ltd. or an equivalent product thereof can be used.

The surface of a clean silicon substrate is hydrophobic. The water-soluble polymer adhering to the surface of the silicon substrate makes the surface of the silicon substrate hydrophilic and lowers the water contact angle. Therefore, the degree of increase in the water contact angle due to the cleaning condition A, that is, the cleaning property parameter α is used as an index, and the water-soluble polymer is subjected to a cleaning treatment using an SC-1 cleaning liquid (hereinafter, also referred to as SC-1 treatment). It is possible to grasp the ease of removal.

A water-soluble polymer having a detergency parameter α greater than 1 tends to be more easily removed by SC-1 treatment than a water-soluble polymer having a detergency parameter α of 1 or less. According to the polishing composition using such a water-soluble polymer, the LPD of the surface after polishing can be effectively reduced even if the SC-1 treatment is performed under milder conditions. Here, the milder condition means a condition in which the load applied to the object to be polished is low and the surface roughness is not easily deteriorated. Therefore, by performing the SC-1 treatment under milder conditions, the haze of the surface after the treatment can be reduced. From this point of view, in some embodiments, the detergency parameter α may be, for example, 2 or more, 3 or more, 4 or more, 5 or more, or 6 or more.

A water-soluble polymer having a detergency parameter α of less than 35 generally has higher adhesion to a silicon substrate than a water-soluble polymer having a detergency parameter α of 35 or more. According to the polishing composition containing such a water-soluble polymer, the water-soluble polymer is appropriately adsorbed on the surface of the silicon substrate during polishing or cleaning to protect the surface, for example, excessive alkaline etching. It is possible to suppress minute roughness of the surface due to such as. Therefore, a polishing composition containing a water-soluble polymer having a detergency parameter α of less than 35 is excellent in haze reducing effect. From the viewpoint of obtaining a higher haze reducing effect, the detergency parameter α may be, for example, 30 or less, 25 or less, 20 or less, 15 or less, or 10 or less. Although not particularly limited, in some embodiments, a water-soluble polymer having a detergency parameter α in the range of 2 or more and 25 or less, or 3 or more and 20 or less, or 4 or more and 15 or less can be preferably adopted.

As the water-soluble polymer WP in the technique disclosed herein, a water-soluble polymer whose detergency parameter α is in the above range can be used without particular limitation. As the water-soluble polymer WP, a polymer having at least one functional group selected from a cationic group, an anionic group and a nonionic group in the molecule is used alone or in combination of two or more. Can be done. More specifically, for example, one or more polymers selected from polymers having a hydroxyl group, a carboxy group, an acyloxy group, a sulfo group, an amide structure, an imide structure, a vinyl structure, a heterocyclic structure and the like in the molecule. It can be used as a water-soluble polymer. In some embodiments, a nonionic polymer can be preferably used as the water-soluble polymer WP, since those showing the preferred α disclosed herein can be easily obtained.

The polishing composition disclosed herein is a water-soluble polymer having a cleanability parameter α higher or lower than the above range in addition to the water-soluble polymer WP whose cleanability parameter α is in the above range. It may contain one or more of the molecules WO as needed. As the water-soluble polymer WO, for example, one having a detergency parameter α of 35 or more or a detergency parameter α of 1 or less can be used. A water-soluble polymer WO having a detergency parameter α of 35 or more and a water-soluble polymer WO having a detergency parameter α of 1 or less may be used in combination. The ratio of the content of the water-soluble polymer WP to the total content of the water-soluble polymer contained in the polishing composition (when two or more kinds of water-soluble polymer WP are contained, the total content thereof) is For example, it may be 25% by weight or more, preferably 40% by weight or more, 50% by weight or more, more than 50% by weight, 70% by weight or more, 80% by weight or more, 95% by weight or more. It may be. As the water-soluble polymer, substantially only the water-soluble polymer WP may be used. Here, "substantially using only the water-soluble polymer WP" means that the water-soluble polymer WO is not used at least intentionally.

Each of the water-soluble polymer WP that can be used in the polishing composition disclosed herein and the water-soluble polymer WO that is used as needed are, for example, vinyl alcohol unit-containing polymer, nitrogen atom-containing polymer, cellulose derivative, and the like. It can be selected from starch derivatives, etc.

The vinyl alcohol unit-containing polymer means a polymer containing a vinyl alcohol unit as a repeating unit constituting the polymer. Here, the vinyl alcohol unit (hereinafter, also referred to as "VA unit") is a structural portion represented by the following chemical formula: -CH ₂ -CH (OH)-;. The VA unit can be produced, for example, by hydrolyzing (also referred to as saponification) a repeating unit having a structure in which a vinyl ester-based monomer such as vinyl acetate is vinyl-polymerized. The polymer generally referred to as polyvinyl alcohol is included in the concept of the vinyl alcohol unit-containing polymer here. The saponification degree of the polyvinyl alcohol may be, for example, about 93% to 99%, but is not particularly limited.

Non-limiting examples of polymers containing nitrogen atoms include polymers containing N-vinyl-type monomer units such as N-vinyllactam, N-vinyl chain amide, etc .; imine derivatives; N- (meth) acryloyl. Polymers containing monomeric units of the type; etc. are included.

Examples of polymers containing N-vinyl type monomer units include polymers containing repeating units derived from monomers having a nitrogen-containing heterocycle. An example of a nitrogen-containing heterocycle is a lactam ring. Examples of polymers containing such repeating units include homopolymers and copolymers of N-vinyllactam type monomers, homopolymers and copolymers of N-vinyl chain amides, and the like. The N-vinyllactam type monomer copolymer may be, for example, a copolymer in which the copolymerization ratio of the N-vinyllactam type monomer exceeds 50% by weight. The copolymer of the N-vinyl chain amide can be, for example, a copolymer in which the copolymerization ratio of the N-vinyl chain amide exceeds 50% by weight.

Unless otherwise specified, the term copolymer in the present specification comprehensively refers to various copolymers such as random copolymers, alternating copolymers, block copolymers, and graft copolymers. be. From the viewpoint of more uniformly protecting the surface of the object to be polished, a random copolymer may be preferably adopted in some embodiments. In particular, when a copolymer is used as the water-soluble polymer WP, a random copolymer can be preferably used as the copolymer.

Specific examples of the N-vinyllactam type monomer include N-vinylpyrrolidone (VP), N-vinylpiperidone, N-vinylmorpholinone, N-vinylcaprolactam (VC), and N-vinyl-1,3-oxazine-2-. On, N-vinyl-3,5-morpholindione and the like can be mentioned. Specific examples of polymers containing N-vinyllactam-type monomer units include polyvinylpyrrolidone, polyvinylcaprolactam, random copolymers of VP and VC, and random copolymerization of one or both of VP and VC and other vinyl monomers. Examples include block copolymers and graft copolymers containing polymer chains containing one or both of coalesced, VP and VC. The other vinyl monomer may be, for example, an acrylic monomer, a vinyl ester monomer, or the like. Here, the acrylic monomer means a monomer having a (meth) acryloyl group.
Specific examples of the N-vinyl chain amide include N-vinylacetamide, N-vinylpropionic acid amide, N-vinylbutyric acid amide and the like.

Examples of polymers containing N- (meth) acryloyl-type monomer units include homopolymers and copolymers of N- (meth) acryloyl-type monomers. Examples of N- (meth) acryloyl-type monomers include chain amides having an N- (meth) acryloyl group and cyclic amides having an N- (meth) acryloyl group. The copolymer of the N- (meth) acryloyl-type monomer can be, for example, a copolymer in which the copolymerization ratio of the N- (meth) acryloyl-type monomer exceeds 50% by weight.

Examples of chain amides having an N- (meth) acryloyl group are (meth) acrylamide; N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-propyl (meth) acrylamide, N-isopropyl ( N-alkyl (meth) acrylamide such as meta) acrylamide and Nn-butyl (meth) acrylamide; N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N, N-dipropyl (meth) ) N, N-dialkyl (meth) acrylamide such as acrylamide, N, N-diisopropyl (meth) acrylamide, N, N-di (n-butyl) (meth) acrylamide; and the like. Examples of polymers containing a chain amide having an N- (meth) acryloyl group as a monomer unit include a homopolymer of N-isopropylacrylamide and a copolymer of N-isopropylacrylamide. The above-mentioned copolymer of N-isopropylacrylamide can be, for example, a copolymer in which the copolymerization ratio of N-isopropylacrylamide exceeds 50% by weight.

Examples of cyclic amides having an N- (meth) acryloyl group include N- (meth) acryloyl morpholine, N- (meth) acryloyl pyrrolidine and the like. Examples of polymers containing a cyclic amide having an N- (meth) acryloyl group as a monomer unit include homopolymers of N-acryloyl morpholine and copolymers of N-acryloyl morpholine. The above-mentioned copolymer of N-acryloyl morpholine can be, for example, a copolymer in which the copolymerization ratio of N-acryloyl morpholine exceeds 50% by weight.

Cellulose derivatives are polymers that contain β-glucose units as the main repeating unit. Specific examples of the cellulose derivative include hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, ethyl cellulose, ethyl hydroxyethyl cellulose, carboxymethyl cellulose and the like. In some embodiments, it is preferred that the polishing composition is substantially free of hydroxyethyl cellulose as the water soluble polymer. Here, substantially not contained means that hydroxyethyl cellulose is not contained at least intentionally. The polishing composition may have a composition that does not substantially contain a cellulose derivative as a water-soluble polymer.

Starch derivatives are polymers that contain α-glucose units as the main repeating unit. Specific examples of the starch derivative include pregelatinized starch, pullulan, carboxymethyl starch, cyclodextrin and the like.

The Mw of the water-soluble polymer is not particularly limited. From the viewpoint of facilitating the acquisition of the suitable detergency parameter α disclosed herein and from the viewpoint of filterability, the Mw of the water-soluble polymer is usually 200 × 10 ⁴ or less, 150 × 10 ⁴ or less, or 100 × 10 ⁴ The following is preferable. From the viewpoint of improving detergency, in some embodiments, the Mw of the water-soluble polymer may be, for example, 50 × ^{104 or less, 30 × 104 or less, 20 × 10 4 or less} , or 10 × It may be 10 ⁴ or less, 5 × 10 ⁴ or less, or 3 × 10 ⁴ or less. Further, from the viewpoint of facilitating the haze reduction effect by polishing, the Mw of the water-soluble polymer is usually 2000 or more, and may be 3000 or more, or 3500 or more. The technique disclosed herein can also be carried out in an embodiment using a water-soluble polymer having an Mw of 1 × 10 ⁴ or more or 2 × ¹⁰⁴ or more. The above Mw can be applied to any of the water-soluble polymers WP and WO.

The detergency parameter α in the techniques disclosed herein can be adjusted, for example, by the water-soluble polymer Mw. In general, the larger the Mw of the water-soluble polymer, the smaller the detergency parameter α tends to be. From this point of view, in some embodiments, the Mw of the water-soluble polymer WP may be, for example, 20 × 10 ⁴ or less, 10 × 10 ⁴ or less, 5 × 10 ⁴ or less, or 3 × 10 ⁴ . It may be less than or equal to, 1.5 × 104 or less, less than ¹ × ¹⁰⁴ , 8000 or less, or 7000 or less. Further, from the viewpoint of enhancing the surface protection effect, the Mw of the water-soluble polymer WP is usually 2000 or more, and may be 3000 or more, or 3500 or more. In some embodiments, the Mw of the water-soluble polymer WP may be 4500 or higher and 5500 or higher. Alternatively, the technique disclosed herein uses a water-soluble polymer WP having an Mw of 1 × 10 ⁴ or more, for example 2 × 10 ⁴ or more, and capable of satisfying the suitable detergency parameter α disclosed herein. However, it can be preferably carried out. Further, in the embodiment in which the water-soluble polymer WP and the water-soluble polymer WO are used in combination, the water-soluble polymer WO has, for example, Mw of 5 × 10 ⁴ or more, 15 × 10 ⁴ or more, or 25 × 10 ⁴ or more. May be used. The technique disclosed herein can be carried out, for example, in a mode including a combination of a water-soluble polymer WP and a water-soluble polymer WO having a Mw larger than that of the water-soluble polymer WP. In such an embodiment, the Mw of the water-soluble polymer WO may be, for example, 1.5 times or more and 50 times or less, 3 times or more and 30 times or less, or 5 times or more with respect to the Mw of the water-soluble polymer WP. It may be 20 times or less. However, the Mw of the water-soluble polymer WP may be larger than the Mw of the water-soluble polymer WO, and the present invention is not limited to the above examples.

The ratio of the weight average molecular weight (Mw) of the water-soluble polymer to the number average molecular weight (Mn), that is, Mw / Mn is not particularly limited. From the viewpoint of preventing the generation of aggregates and improving the filterability, the Mw / Mn of the water-soluble polymer is usually preferably 10.0 or less, more preferably 7.0 or less, still more preferably 5.0. It is as follows. In some embodiments, water-soluble polymers with Mw / Mn of 4.0 or less or 3.5 or less may be preferably employed. Further, Mw / Mn is 1.0 or more in principle, and may be 1.2 or more, or 1.5 or more, for example, from the viewpoint of availability of materials and the like. The above Mw / Mn can be applied to any of the water-soluble polymers WP and WO.
In the present specification, as Mw and Mn of the water-soluble polymer, values based on water-based gel permeation chromatography (GPC) (water-based, in terms of polyethylene oxide) can be adopted.

In some preferred embodiments of the polishing composition disclosed herein, the water-soluble polymer WP is also referred to as a vinyl alcohol unit (VA unit) and a non-vinyl alcohol unit (hereinafter, "non-VA unit") in one molecule. A polymer containing) can be used. The non-VA unit is, for example, a hydrocarbon group such as an alkyl group, an aryl ether group, an aryl group, an arylalkyl group or a styrene group; an oxy hydrocarbon such as an alkoxy group, an aryloxy group, an arylalkyloxy group or an oxyalkylene group. Groups; at least selected from the group consisting of carboxy groups, sulfo groups, amino groups, hydroxyl groups, amide groups, imide groups, imino groups, amidino groups, imidazolino groups, nitrile groups, ether groups, ester groups, and salts thereof; It can be a repeating unit containing one structure. The molar ratio of VA units: non-VA units can be set so that a suitable detergency parameter α is obtained. The molar ratio of VA unit: non-VA unit may be, for example, 50:50 or more, 65:35 or more, 70:30 or more, 75:25 or more, or 80:20 or more. In some embodiments, the VA unit: non-VA unit molar ratio may be 85:15 or greater, 90:10 or greater, or greater than 90:10. The molar ratio of VA unit: non-VA unit may be, for example, 99: 1 or less, 98: 2 or less, or 97: 3 or less. In some embodiments, the molar ratio of VA units: non-VA units may be 95: 5 or less, or 93: 7 or less.

The polymer containing VA units and non-VA units in the above molecule can be, for example, a polymer containing VA units and VP units. Here, the VP unit refers to a repeating unit of a structure formed by vinyl polymerization of N-vinylpyrrolidone. The polymer containing the VA unit and the VP unit may be a random copolymer, a graft copolymer, or a block copolymer.

The random copolymer containing the VA unit and the VP unit can be formed by modifying a random copolymer of a monomer that can be converted into a VA unit and N-vinylpyrrolidone. For example, a random copolymer containing vinyl acetate and N-vinylpyrrolidone can be partially saponified or completely saponified to obtain a random copolymer containing VA units and VP units. The molar ratio of VA unit: VP unit in such a random copolymer may be, for example, 50:50 or more, 65:35 or more, 70:30 or more, 75:25 or more, 80:20. The above may be sufficient. The molar ratio of VA unit: VP unit may be, for example, 99: 1 or less, 97: 3 or less, 95: 5 or less, or 93: 7 or less.

The graft copolymer or block copolymer containing the VA unit and the VP unit can be a polymer containing a VA-based segment and a VP-based segment. Here, the VA-based segment refers to a segment in which the ratio of the number of moles of VA units to the total number of moles of repeating units constituting the segment is more than 50%. The ratio of the number of moles of the VA unit may be 70% or more, 80% or more, 90% or more, 95% or more, 98% or more, or substantially 100%. Here, substantially 100% means that non-VA units are not contained at least intentionally. When the VA-based segment contains non-VA units, the non-VA units may include VP units, non-VA units other than VP units, or both. The VP-based segment refers to a segment in which the ratio of the number of moles of VP units to the total number of moles of repeating units constituting the segment is more than 50%. The ratio of the number of moles of the VP unit may be 70% or more, 80% or more, 90% or more, 95% or more, 98% or more, or substantially 100%. Here, substantially 100% means that, at least intentionally, no repeating unit other than the VP unit is contained. The copolymer having the VA unit and the VP unit can be, for example, a graft copolymer having a structure in which the VP-based segment is grafted on the VA-based segment.

Other examples of polymers containing VA and non-VA units in the above molecule include copolymers with VA and monocarboxylic acid vinyl ester units, copolymers with VA and ethylene units, VA units and R. -Copolymers having vinyl ether units, copolymers having VA units and oxyalkylene units, polymers in which a part of VA units are acetalized with aldehydes such as formaldehyde, acetaldehyde, propionaldehyde, n-butylaldehyde, etc. Can be mentioned. These polymers may be random copolymers, graft copolymers or block copolymers. Further, in these polymers, the molar ratio of VA unit: non-VA unit may be, for example, 50:50 or more, 65:35 or more, 70:30 or more, 75:25 or more, 80. : 20 or more may be used. The molar ratio of VA unit: non-VA unit may be, for example, 99: 1 or less, 97: 3 or less, 95: 5 or less, or 93: 7 or less.

The monocarboxylic acid vinyl ester unit is a repeating unit derived from the monocarboxylic acid vinyl ester. Non-limiting examples of monocarboxylic acid vinyl esters include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl hexanoate, vinyl caprylate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate. , Vinyl pivalate and the like. Preferable examples of the monocarboxylic acid vinyl ester unit include vinyl acetate unit, vinyl propionate unit, vinyl hexanoate unit and the like. For example, by partially or completely saponifying a random copolymer of vinyl acetate and another monocarboxylic acid vinyl ester, a random copolymer containing a VA unit and a monocarboxylic acid vinyl ester unit can be obtained.

The R-vinyl ether unit is a repeating unit having a structure in which the corresponding R-vinyl ether (RO-CH = CH ₂ ) is vinyl-polymerized. R in the above R-vinyl ether can be a chain or cyclic alkyl group, an aryl group, an arylalkyl group, or the like. R-vinyl ether in which R is an alkyl group, that is, an alkyl vinyl ether is preferable. The number of carbon atoms of the alkyl group in the alkyl vinyl ether unit may be, for example, 1 to 12, may be 1 to 8, or may be 1 to 4. Specific examples of the alkyl vinyl ether unit include methyl vinyl ether unit, ethyl vinyl ether unit, n-propyl vinyl ether unit, i-propyl vinyl ether unit, n-butyl vinyl ether unit, i-butyl vinyl ether unit, t-butyl vinyl ether unit, and 2-ethylhexyl. Examples include vinyl ether units. In the copolymer having VA unit and R-vinyl ether unit, the molar ratio of VA unit: R-vinyl ether unit may be, for example, 50:50 or more, 65:35 or more, 70:30 or more. It may be 75:25 or more, or 80:20 or more. Further, in the above-mentioned copolymer, the molar ratio of VA unit: R-vinyl ether unit may be, for example, 99: 1 or less, 97: 3 or less, 95: 5 or less, or 93: 7 or less. ..

The copolymer having the VA unit and the oxyalkylene unit may be a graft copolymer or a block copolymer containing a VA-based segment and an oxyalkylene-based segment. Here, the oxyalkylene-based segment refers to a segment containing an oxyalkylene unit. The oxyalkylene unit is a repeating unit represented by the following chemical formula: -AO- ;. A in the above chemical formula is preferably an alkylene group having 2 to 4 carbon atoms. The oxyalkylene unit can be derived, for example, from the corresponding alkylene oxide. The ratio of the number of moles of the oxyalkylene unit to the total number of moles of the repeating units constituting the oxyalkylene segment is typically 50% or more, 70% or more, 80% or more, 90% or more. However, it may be 95% or more, 98% or more, and substantially 100%. Here, "substantially 100%" means that, at least intentionally, no repeating unit other than the oxyalkylene unit is contained. The oxyalkylene segment can be a polymer in which the oxyalkylene unit is typically 5 units or more, preferably 10 units or more, more preferably 20 units or more, for example, 30 units or more. The oxyalkylene unit contained in the oxyalkylene-based segment may be one type or two or more types. As the oxyalkylene-based segment, an oxyethylene-based segment or an oxypropylene-based segment is preferable, and an oxyethylene-based segment is more preferable. The composition of the VA-based segment can be similar to that of the VA-based segment in the polymer containing the VA-based segment and the VP-based segment described above. The copolymer having the VA unit and the oxyalkylene unit can be, for example, a graft copolymer having a structure in which an oxyethylene-based segment is grafted on a VA-based segment.

The polymer containing VA units and non-VA units in the above-mentioned molecule may be a modified polyvinyl alcohol having a hydrophilic functional group in its side chain. Examples of the hydrophilic functional group include an oxyalkylene group, a carboxy group, a sulfo group, an amino group, a hydroxyl group, an amide group, an imide group, a nitrile group, an ether group, an ester group, and salts thereof. The modified polyvinyl alcohol may be, for example, a cationized polyvinyl alcohol having a cationic group such as a quaternary ammonium structure. Examples of the cationized polyvinyl alcohol include those derived from monomers having a cationic group such as diallyldialkylammonium salt and N- (meth) acryloylaminoalkyl-N, N, N-trialkylammonium salt. ..

Although not particularly limited, the content of the water-soluble polymer in the polishing composition (the total amount thereof when two or more kinds are contained) is, for example, 20 parts by weight or less with respect to 100 parts by weight of the abrasive grains. Can be. The content of the water-soluble polymer with respect to 100 parts by weight of the abrasive grains may be, for example, 10 parts by weight or less, 7 parts by weight or less, or 5 parts by weight or less from the viewpoint of improving the detergency and the polishing speed. From the viewpoint of facilitating the reduction of LPD even by washing under lower load conditions, the content of the water-soluble polymer with respect to 100 parts by weight of the abrasive grains may be 4 parts by weight or less and 3 parts by weight or less in some embodiments. However, it may be 2 parts by weight or less. Further, from the viewpoint of enhancing the haze reduction effect by polishing, the content of the water-soluble polymer with respect to 100 parts by weight of the abrasive grains may be, for example, 0.01 part by weight or more, and usually 0.05 part by weight or more is appropriate. Yes, it may be 0.1 parts by weight or more, 0.5 parts by weight or more, or 1 part by weight or more. The polishing composition disclosed herein contains a water-soluble polymer satisfying the above-mentioned detergency parameter α, so that the content of the water-soluble polymer with respect to 100 parts by weight of the abrasive grains is 1.2 parts by weight or more or 1 A low LPD surface can be achieved by cleaning under relatively low load conditions, even in embodiments of 4 parts by weight or more.

<Surfactant>
The polishing composition disclosed herein may contain a surfactant. Here, the surfactant refers to a compound having a surfactant action. Surfactants have a function of reducing haze together with water-soluble polymers. Surfactants can also contribute to improving the dispersion stability and filterability of the polishing composition. As the surfactant, any of anionic, nonionic, cationic and amphoteric ones can be used. The surfactant may be used alone or in combination of two or more.

The anionic surfactant refers to a compound having a functional group and a hydrophobic group that dissociate in water to become anions and having a surface-active action. Anionic surfactants can be classified into, for example, sulfuric acid-based, sulfonic acid-based, phosphoric acid-based, phosphonic acid-based, carboxylic acid-based, and the like. Specific examples of anionic surfactants include alkyl sulphate ester, polyoxyethylene alkyl sulphate ester, polyoxyethylene alkyl sulphate, alkyl sulphate, alkyl ether sulphate ester, higher alcohol sulphate ester, alkyl phosphate ester, alkylbenzene sulfonic acid, α. -Olefin sulfonic acid, alkyl sulfonic acid, styrene sulfonic acid, alkylnaphthalene sulfonic acid, alkyldiphenyl ether disulfonic acid, polyoxyethylene alkyl ether acetic acid, polyoxyethylene alkyl ether phosphoric acid, polyoxyethylene alkyl phosphate ester, polyoxyethylene sulfosuccinate Includes acids, alkyl sulfosuccinic acids, salts of any of the compounds mentioned above, and the like. A specific example of alkyl sulfonic acid is dodecyl sulfonic acid. Other examples of anionic surfactants include taurine-based surfactants, sarcosinate-based surfactants, isetionate-based surfactants, N-acyl acidic amino acid-based surfactants, higher fatty acid salts, acylated polypeptides, and the like. Be done.

Examples of nonionic surfactants are polyalkylene glycols such as polyethylene glycol, polypropylene glycol and polytetramethylene glycol; polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene alkyl amines and polyoxyethylene. Polyoxyalkylene derivatives such as fatty acid esters, polyoxyethylene glyceryl ether fatty acid esters, polyoxyethylene sorbitan fatty acid esters, etc., eg polyoxyalkylene adducts; polymers containing multiple oxyalkylene units, eg diblock type Polymers, triblock copolymers, random copolymers, alternating copolymers; other examples include sucrose fatty acid esters, sorbitan fatty acid esters, glycerin fatty acid esters, alkyl alkanolamides and the like.

Cationic surfactants can be classified into, for example, polyoxyethylene alkylamines, alkylalkanolamides, alkylamine salts, amine oxides, quaternary ammonium salts, tertiary amidoamine-type surfactants, and the like. Specific examples of the cationic surfactant include coconutamine acetate, stearylamine acetate, lauryldimethylamine oxide, dimethylaminopropylamide stearate, alkyltrimethylammonium salt, alkyldimethylammonium salt, alkylbenzyldimethylammonium salt and the like. Be done.

Specific examples of amphoteric surfactants include alkyl betaine-based, alkyl amine oxide-based, and the like. Specific examples of the amphoteric tenside include cocobetaine, lauramidopropyl betaine, cocamidopropyl betaine, sodium lauroanphoacetate, sodium cocoamphoacetate, coconut oil fatty acid amide propyl betaine, lauryl betaine (betaine lauryldimethylaminoacetate) and the like. Be.

In some embodiments, surfactants containing a polyoxyalkylene structure may be preferably employed. The polyoxyalkylene structure refers to a repeating structure in which two or more oxyalkylene units, preferably three or more, are continuous. The oxyalkylene unit can be a repeating unit derived from the corresponding alkylene oxide. Therefore, the number of repetitions of the oxyalkylene unit can also be grasped as the number of moles of alkylene oxide added. For example, anionic or nonionic surfactants containing a polyoxyalkylene structure can be preferably used.

The oxyalkylene unit is preferably an oxyalkylene group having 2 to 18 carbon atoms. Here, the alkylene group may be substituted with an aryl group. Such an oxyalkylene group can be derived from, for example, ethylene oxide, propylene oxide, 1,2-butylene oxide, 2,3-butylene oxide, styrene oxide and the like. The oxyalkylene unit is an oxyalkylene group having 2 to 10 carbon atoms from the viewpoint of easy availability, easy dispersion of the surfactant in the polishing composition, and easy reduction of haze on the polished surface. Is more preferable, and an oxyalkylene group having 2 or more and 4 or less carbon atoms is further preferable. Among them, preferred oxyalkylene units include an oxyethylene group and an oxypropylene group. Oxyethylene groups are particularly preferred.

Anionic surfactants containing a polyoxyalkylene structure include sulfate ester (RO-SO ₃ ^- H ⁺ ) and a salt thereof (RO-SO ₃ ^- M ⁺ ), and sulfonic acid (R-SO ₃ ^- H +). ⁺ ) And its salt (R-SO ₃ ^- M ⁺ ), carboxylic acid (R-COO ^- H ⁺ ) and its salt (R-COO ^- M ⁺ ), and phosphate ester (RO ^- PO (O-)). It is preferable to be selected from the group consisting of H ⁺ ) ₂ ) and its salt (RO-PO (OH ⁺ ) (O ^- M ⁺ ) or R-O ^{-PO (O- M +} ) ₂ ). , Not limited to these. In the above, "R" represents an organic group containing a polyoxyalkylene structure. Further, in the above, "M ⁺ " represents various cations such as metal cations and ammonium cations. From the viewpoint of easy reduction of haze, the anionic surfactant is preferably selected from the group consisting of sulfate esters and salts thereof, carboxylic acids and salts thereof, and phosphate esters and salts thereof, and sulfate esters and salts thereof. , And more preferably selected from the group consisting of carboxylic acids and salts thereof. Here, from the viewpoint that haze can be reduced more effectively, the carboxylic acid and its salt are acetic acid (R'-CH ₂ COO ^- H ⁺ ) having an organic group containing a polyoxyalkylene structure and its salt (R'. It is preferably selected from the group consisting of -CH ₂ COO ^- M ⁺ ). Here, "R'" represents an organic group containing a polyoxyalkylene structure. Therefore, from the viewpoint of further improving the haze reducing effect, it is particularly preferable that the anionic surfactant is selected from the group consisting of the sulfate ester and its salt, and the acetic acid and its salt.

When classified by the above "M ⁺ ", the types of the above salts include alkali metal salts such as sodium and potassium, salts of Group 2 elements such as calcium and magnesium, ammonium salts, alkanolamine salts such as triethanolamine, and the like. And so on.

Further, one molecule of the anionic surfactant includes the above-mentioned anionic portion (that is, "-O ^- SO _3- " portion, "SO _3- " portion ^, " ^COO- " portion, and "-O-PO (OH)". ) ^O- "part and two or more selected from" -O-PO ( ^O- ) ₂ ") may be included.

In an anionic surfactant containing a polyoxyalkylene structure, the average number of moles of oxyalkylene units constituting the polyoxyalkylene structure is preferably more than 3 and 25 or less. According to an anionic surfactant having an average number of moles added of more than 3 in the oxyalkylene unit, the anionic surfactant protects the surface of the object to be polished such as a silicon substrate, so that a high haze reducing effect is likely to be exhibited. .. Further, when the average number of moles of oxyalkylene units contained in the anionic surfactant exceeds 25, the surface protection of the object to be polished such as a silicon substrate by the anionic surfactant becomes excessive, and the polishing rate decreases. It can be easier to do. From the viewpoint of reducing haze while suppressing a decrease in polishing rate, the average number of moles added of the oxyalkylene unit is preferably 4 or more, and more preferably 4.5 or more. From the same viewpoint, the average number of moles of oxyalkylene units added is preferably 20 or less, and more preferably 18 or less. From the above, from the viewpoint of achieving both reduction of haze and improvement of polishing speed, the average number of moles added of the oxyalkylene unit is preferably 4 or more and 20 or less, and 4.5 or more and 18 or less. preferable. In some embodiments, the average number of moles of oxyalkylene units added may be, for example, 6 or more, 10 or more, or 14 or more.
The "average number of moles added" means the average value of the number of moles of alkylene oxide added in one mole of the surfactant (that is, the number of moles of oxyalkylene units). If two or more different oxyalkylene units are contained in the surfactant, the average value thereof shall be adopted. The average number of moles of the alkylene oxide added can be appropriately measured by ¹ H-NMR, gas chromatography (GC), GPC, gel filtration chromatography (GFC), titration method or the like. For the average number of moles added, the value measured by the method described in Examples is adopted.

In some cases, two or more different oxyalkylene units may be present in the anionic surfactant. From the viewpoint of ease of production of the polyoxyalkylene chain and ease of controlling the structure, it is preferable that the oxyalkylene unit is the same repetition.

The sulfuric acid ester and a salt thereof used as an anionic surfactant containing a polyoxyalkylene structure are not particularly limited, and are not particularly limited, for example, polyoxyethylene lauryl ether sulfuric acid, polyoxyethylene myristyl ether sulfuric acid, and polyoxyethylene palmityl ether sulfuric acid. Sodium polyoxyethylene lauryl ether sulfate, ammonium polyoxyethylene lauryl ether sulfate, triethanolamine polyoxyethylene lauryl ether sulfate, sodium polyoxyethylene myristyl ether sulfate, ammonium polyoxyethylene myristyl ether sulfate, triethanolamine polyoxyethylene myristyl ether sulfate , Polyoxyethylene palmityl ether sulfate sodium, polyoxyethylene palmityl ether sulfate amine, polyoxyethylene palmityl ether sulfate triethanolamine and the like. Among these, sodium polyoxyethylene lauryl ether sulfate and ammonium polyoxyethylene lauryl ether sulfate are preferable.

The sulfonic acid used as an anionic surfactant containing a polyoxyalkylene structure and a salt thereof are not particularly limited, and are, for example, polyoxyethylene octylsulfonic acid, polyoxyethylene laurylsulfonic acid, and polyoxyethylene palmitylsulfonic acid. , Polyoxyethylene octylbenzene sulfonic acid, polyoxyethylene laurylbenzene sulfonic acid; sodium polyoxyethylene octylsulfonic acid, sodium polyoxyethylene lauryl sulfonic acid, sodium polyoxyethylene palmityl sulfonic acid and the like. Among these, polyoxyethylene octyl sulfonic acid and sodium polyoxyethylene octyl sulfonic acid are preferable.

The carboxylic acid and its salt used as an anionic surfactant containing a polyoxyalkylene structure are not particularly limited, and are, for example, polyoxyethylene lauryl ether acetic acid, polyoxyethylene tridecyl ether acetic acid, and polyoxyethylene octyl ether acetic acid. Polyoxyethylene lauryl ether sodium acetate, polyoxyethylene lauryl ether ammonium acetate, polyoxyethylene tridecyl ether acetate sodium polyoxyethylene tridecyl ether ammonium acetate, polyoxyethylene octyl ether sodium acetate, polyoxyethylene octyl ether ammonium acetate Such as, acetic acid containing a polyoxyalkylene structure and a salt thereof. Among these, polyoxyethylene lauryl ether sodium acetate and polyoxyethylene lauryl ether ammonium acetate are preferable.

The phosphate ester and a salt thereof used as an anionic surfactant containing a polyoxyalkylene structure are not particularly limited, and are, for example, polyoxyethylene lauryl ether phosphoric acid and polyoxyethylene alkyl (12-15) ether phosphoric acid. Examples thereof include sodium polyoxyethylene lauryl ether phosphate, sodium polyoxyethylene oleyl ether phosphate, sodium polyoxyethylene palmityl ether phosphate, and potassium polyoxyethylene alkyl (12-15) ether phosphate. Among these, polyoxyethylene alkyl (12-15) ether phosphoric acid and sodium polyoxyethylene lauryl ether phosphate are preferable.

Examples of anionic surfactants containing two or more of the above anionic moieties in one molecule include polyoxyethylene lauryl sulfosuccinate disodium salt, sulfosuccinate polyoxyethylene lauroylethanolamide disodium salt and the like. ..

In such an anionic surfactant, the structure of the ω-terminal hydrophobic group is not particularly limited, and for example, a substituted or unsubstituted C2 or more and C30 or less alkyl group, a substituted or unsubstituted C3 or more and C20 or less cyclo Alkyl groups, substituted or unsubstituted C1 or more and C30 or less alkyl ester groups, substituted or unsubstituted C6 or more and C20 or less aryl groups, C1 or more and C30 or less alkyl groups, mono or dialkylamide groups, C1 or more and C30 or less It may be substituted with a mono or dialkylamino group having an alkyl group, or may have a sorbitan structure. Here, "CX or more and CY or less" means that the number of carbon atoms is X or more and Y or less.

Examples of the alkyl group include ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, neopentyl group, 1, Examples thereof include 2-dimethylpropyl group, n-hexyl group, n-hebutyl group, n-octyl group, 2-ethylhexyl group, n-decyl group and n-dodecyl group.

Examples of the cycloalkyl group include a cyclopentyl group and a cyclohexyl group.

Examples of the alkyl ester group include a methyl ester group, an ethyl ester group, an n-propyl ester group, an i-propyl ester group, an n-butyl ester group, a 2-methylpropyl ester group and the like.

Examples of the aryl group include a phenyl group, an o-, m- or p-tolyl group.

As used herein, the term "substituted or unsubstituted" group means that the hydrogen atom in the group is a halogen atom such as a fluorine atom, a chlorine atom or a bromine atom; a cyano group; a nitro group; a hydroxy group; C1 or more and C10. The following linear or branched alkyl groups; C1 or more and C10 or less linear or branched alkoxy groups; C6 or more and C30 or less aryl groups; C2 or more and C30 or less heteroaryl groups; C5 or more and C20 or less Cycloalkyl group; means substituted or unsubstituted with a substituent such as.

Such anionic surfactants may be used alone or in combination of two or more.

In some embodiments, as the anionic surfactant containing a polyoxyalkylene structure, the polyoxyalkylene structure is a polyoxyethylene structure, and the average number of moles of ethylene oxide added in the polyoxyethylene structure is 3. Those exceeding 25 or less can be preferably adopted. From the viewpoint of reducing haze while suppressing a decrease in polishing rate, the average number of moles of ethylene oxide added is preferably 4 or more, and more preferably 4.5 or more. From the same viewpoint, the average number of moles of ethylene oxide added is preferably 20 or less, and more preferably 18 or less. From the above, the average number of moles of ethylene oxide added to the anionic surfactant is preferably 4 or more and 20 or less, and more preferably 4.5 or more and 18 or less.

In a nonionic surfactant containing a polyoxyalkylene structure, the polyoxyalkylene structure can be, for example, a polyoxyethylene structure, a polyoxypropylene structure, a polyoxybutylene structure, or the like. Of these, a nonionic surfactant containing a polyoxyethylene structure is preferable. The polyoxyalkylene structure may be a repeating structure in which the oxyalkylene unit is at least 2 units or more, preferably 3 units or more. The number of repetitions of the oxyalkylene unit in the polyoxyalkylene structure may be, for example, 5 units or more, 10 units or more, 15 units or more, 20 units or more, 30 units or more, 50 units or more. It may be.

Specific examples of the nonionic surfactant containing a polyoxyalkylene structure include a block copolymer of ethylene oxide (EO) and propylene oxide (PO), a random copolymer of EO and PO, and polyoxyethylene glycol. Polyoxyethylene propyl ether, polyoxyethylene butyl ether, polyoxyethylene pentyl ether, polyoxyethylene hexyl ether, polyoxyethylene octyl ether, polyoxyethylene-2-ethylhexyl ether, polyoxyethylene nonyl ether, polyoxyethylene decyl ether, Polyoxyethylene isodecyl ether, polyoxyethylene tridecyl ether, polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene isostearyl ether, polyoxyethylene oleyl ether, polyoxyethylene phenyl ether , Polyoxyethylene octylphenyl ether, polyoxyethylene nonylphenyl ether, polyoxyethylene dodecylphenyl ether, polyoxyethylene styrene phenyl ether, polyoxyethylene laurylamine, polyoxyethylene stearylamine, polyoxyethylene oleylamine, polyoxyethylene Monolauric acid ester, polyoxyethylene monostearic acid ester, polyoxyethylene distearate, polyoxyethylene monooleic acid ester, polyoxyethylene dioleic acid ester, monolauric acid polyoxyethylene sorbitan, monopaltimate polyoxyethylene sorbitan, Examples thereof include polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan trioleate, polyoxyethylene sorbit tetraoleate, polyoxyethylene castor oil, and polyoxyethylene cured castor oil. Examples of the block copolymer of EO and PO include a diblock type copolymer, a PEO (polyethylene oxide) -PPO (polypropylene oxide) -PEO type triblock body, and a PPO-PEO-PPO type triblock. Copolymers and the like are included. Among them, preferable surfactants include block copolymers of EO and PO, random copolymers of EO and PO, and polyoxyethylene alkyl ethers. As a preferred example of the block copolymer of EO and PO, a PEO-PPO-PEO type triblock copolymer is particularly preferable. Moreover, a polyoxyethylene decyl ether is mentioned as a preferable example of a polyoxyethylene alkyl ether.

The weight average molecular weight (Mw) of the surfactant is not particularly limited and may be, for example, less than 12000. In some embodiments, the Mw of the surfactant may be, for example, less than 10,000, may be 9,500 or less, may be 9000 or less, or may be 8000 or less, from the viewpoint of filterability, detergency and the like. Further, the Mw of the surfactant is usually preferably 200 or more from the viewpoint of surfactant ability and the like, preferably 250 or more from the viewpoint of haze reducing effect and the like, and may be 300 or more, for example.
A more preferred range of Mw for a surfactant may also vary depending on the type of surfactant. For example, the Mw of the anionic surfactant containing a polyoxyalkylene structure is preferably 5000 or less, more preferably 4000 or less, still more preferably 3000 or less. The Mw of the anionic surfactant containing the polyoxyalkylene structure is preferably 200 or more, more preferably 300 or more, and further preferably 400 or more.
Further, for example, when polyoxyethylene alkyl ether is used as the surfactant, its Mw is preferably 2000 or less, and may be 1000 or less, for example, 500 or less. The Mw of the polyoxyethylene alkyl ether is preferably 200 or more, and more preferably 300 or more.
Further, when a block copolymer of EO and PO such as a PEO-PPO-PEO type triblock copolymer is used as a surfactant, the Mw thereof may be, for example, 1000 or more, and 3000 or more. Further, it may be 5000 or more. The Mw of the PEO-PPO-PEO type triblock copolymer may be, for example, 12000 or less, and may be less than 10000.
In this specification, as a method for grasping the Mw of the surfactant, a method of calculating based on the molecular structure can be adopted.

Although not particularly limited, in the polishing composition disclosed herein, the content of the surfactant per 100 parts by weight of the abrasive grains (when two or more kinds are contained, the total content thereof) is the polishing rate. From the viewpoint of suppressing the decrease in the amount of water, 10 parts by weight or less is usually suitable, and 5 parts by weight or less, 3 parts by weight or less, or 2 parts by weight or less may be used. Depending on the case, the content of the surfactant may be 1 part by weight or less, 0.5 part by weight or less, or 0.3 part by weight or less. Further, from the viewpoint of better exerting the effect of using the surfactant, for example, the haze reducing effect, the content of the surfactant with respect to 100 parts by weight of the abrasive grains is usually 0.001 part by weight or more, and is 0. It is preferably .005 parts by weight or more, preferably 0.01 parts by weight or more, 0.03 parts by weight or more, and for example, 0.05 parts by weight or more. Depending on the case, the content of the surfactant may be 0.07 parts by weight or more, 0.1 parts by weight or more, 0.3 parts by weight or more, 0.5 parts by weight or more, and 0. It may be 7 parts by weight or more.

A more preferable amount of the surfactant to be used may also vary depending on the type of the surfactant. For example, when an anionic surfactant containing a polyoxyalkylene structure is used, the content of the surfactant with respect to 100 parts by weight of the abrasive grains may be, for example, 1.5 parts by weight or less, or 1 part by weight or less. , 0.5 parts by weight or less, 0.3 parts by weight or less, or 0.2 parts by weight or less.
Further, when a block copolymer of EO and PO such as a PEO-PPO-PEO type triblock copolymer is used as the surfactant, the content of the surfactant with respect to 100 parts by weight of the abrasive grains is For example, it may be 0.07 parts by weight or more, 0.1 parts by weight or more, 0.3 parts by weight or more, 0.5 parts by weight or more, or 0.7 parts by weight or more.

In the polishing composition disclosed herein, the weight ratio w1 / w2 of the content w1 of the water-soluble polymer and the content w2 of the surfactant is not particularly limited. The weight ratio w1 / w2 can be, for example, in the range of 0.01 to 100, preferably in the range of 0.05 to 50. From the viewpoint of achieving both low surface roughness and low LPD at a higher level, the weight ratio w1 / w2 may be, for example, 30 or less, 25 or less, 20 or less, or 15 or less. From the same viewpoint, the weight ratio w1 / w2 may be, for example, 0.1 or more, 0.5 or more, 1 or more, or 1.5 or more. In some embodiments, the weight ratio w1 / w2 may be 3 or more, or 5 or more. Further, the technique disclosed herein can also be preferably carried out in an embodiment in which the weight ratio w1 / w2 is 10 or less or 7 or less.

The more preferable range of the weight ratio w1 / w2 may differ depending on the type of surfactant. For example, when an anionic surfactant containing a polyoxyalkylene structure is used, the weight ratio w1 / w2 may be, for example, 1.5 or more, 3 or more, 5 or more, or 8 or more. It may be 10 or more.
Further, when a block copolymer of EO and PO such as a PEO-PPO-PEO type triblock copolymer or the like is used as the surfactant, the weight ratio w1 / w2 may be 12 or less, for example. , 9 or less, 7 or less, 4 or less, or 2 or less.

<Basic compound>
The polishing compositions disclosed herein typically contain a basic compound. Here, the basic compound refers to a compound having a function of raising the pH of the composition by being added to the polishing composition. The basic compound has a function of chemically polishing the surface of the object to be polished by etching. In addition, the basic compound can be used as a pH adjuster.

As the basic compound, an organic or inorganic basic compound containing nitrogen, an alkali metal hydroxide, an alkaline earth metal hydroxide, various carbonates, hydrogen carbonate and the like can be used. Examples of nitrogen-containing basic compounds include quaternary ammonium compounds, ammonia, amines and the like. As the amine, a water-soluble amine is preferable. Basic compounds also include quaternary phosphonium compounds. Such basic compounds may be used alone or in combination of two or more.

Specific examples of alkali metal hydroxides include potassium hydroxide and sodium hydroxide. Specific examples of the carbonate or hydrogen carbonate include ammonium hydrogen carbonate, ammonium carbonate, potassium hydrogen carbonate, potassium carbonate, sodium hydrogen carbonate, sodium carbonate and the like. Specific examples of amines include methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, ethylenediamine, monoethanolamine, N- (β-aminoethyl) ethanolamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, and piperazine anhydride. , Piperazine hexahydrate, 1- (2-aminoethyl) piperazine, N-methylpiperazine, guanidine, azoles such as imidazole and triazole, and the like. Specific examples of the quaternary phosphonium compound include quaternary phosphonium hydroxides such as tetramethylphosphonium hydroxide and tetraethylphosphonium hydroxide.

As the quaternary ammonium compound, a quaternary ammonium salt such as a tetraalkylammonium salt or a hydroxyalkyltrialkylammonium salt can be preferably used. The anionic component in such a quaternary ammonium salt can be, for example, OH ⁻ , F ⁻ , Cl ⁻ , Br ⁻ , I ⁻ , ClO _4- ^, BH _4- ^and the like. As the quaternary ammonium salt, a strong base salt is preferable. Among them, a preferable example is a quaternary ammonium salt having an anion of OH ⁻ , that is, a quaternary ammonium hydroxide. Specific examples of the quaternary ammonium hydroxide include hydroxylation of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetrapentylammonium hydroxide and tetrahexylammonium hydroxide. Tetraalkylammonium; hydroxyalkyltrialkylammonium hydroxide such as 2-hydroxyethyltrimethylammonium (also referred to as choline); and the like.

Of these basic compounds, for example, at least one basic compound selected from alkali metal hydroxides, quaternary ammonium hydroxides and ammonia can be preferably used. Among them, tetraalkylammonium hydroxide such as tetramethylammonium hydroxide and ammonia are more preferable, and ammonia is particularly preferable.

<Water>
The polishing composition disclosed herein typically comprises water. As the water, ion-exchanged water (deionized water), pure water, ultrapure water, distilled water and the like can be preferably used. The water used preferably has, for example, a total content of transition metal ions of 100 ppb or less in order to avoid hindering the action of other components contained in the polishing composition as much as possible. For example, the purity of water can be increased by operations such as removal of impurity ions by an ion exchange resin, removal of foreign substances by a filter, and distillation.

<Other ingredients>
In addition, the polishing compositions disclosed herein include chelating agents, organic acids, organic acid salts, inorganic acids, inorganic acid salts, preservatives, antifungal agents, etc., as long as the effects of the present invention are not significantly impaired. , Known additives that can be used in the polishing slurry may be further contained, if necessary. The additive may be, for example, a known additive that can be used in a polishing composition used in a polishing step of a silicon wafer.

The polishing composition disclosed herein preferably contains substantially no oxidizing agent. When the polishing composition contains an oxidizing agent, the surface of the polishing object is oxidized to form an oxide film when the polishing composition is supplied to the polishing object such as a silicon wafer. This is because the polishing efficiency may decrease due to the above. Specific examples of the oxidizing agent referred to here include hydrogen peroxide (H ₂ O ₂ ), sodium persulfate, ammonium persulfate, sodium dichloroisocyanurate and the like. The fact that the polishing composition does not substantially contain an oxidizing agent means that the polishing composition does not contain an oxidizing agent at least intentionally.

<pH>
The pH of the polishing composition disclosed herein is typically 8.0 or higher, preferably 8.5 or higher, more preferably 9.0 or higher, still more preferably 9.3 or higher, for example 9. 5 or more. As the pH of the polishing composition increases, the polishing efficiency tends to improve. On the other hand, from the viewpoint of preventing the dissolution of abrasive grains, for example, silica particles, and suppressing the decrease in mechanical polishing action, the pH of the polishing composition is preferably 12.0 or less, and is 11.0 or less. It is preferably 10.8 or less, more preferably 10.5 or less. The pH of the polishing composition refers to the pH at 20 ° C to 25 ° C.

In the techniques disclosed herein, the pH of a liquid composition is calibrated at three points using a standard buffer using a pH meter, and then the glass electrode is placed in the composition to be measured for 2 minutes. It can be grasped by measuring the value after the above elapse and stabilization. The standard buffers are phthalate pH buffer pH: 4.01 (25 ° C), neutral phosphate pH buffer pH: 6.86 (25 ° C), carbonate pH buffer pH: 10.01. (25 ° C.). As the pH meter, for example, LAQUA (registered trademark) manufactured by HORIBA, Ltd. or an equivalent product thereof can be used.

<Polishing composition>
The polishing composition disclosed herein is typically supplied to an object to be polished in the form of a polishing solution containing the composition for polishing, and is used for polishing the object to be polished. The polishing liquid may be prepared by diluting any of the polishing compositions disclosed herein, for example. Dilution of the polishing composition can typically be done with water. Alternatively, the polishing composition may be used as it is as a polishing liquid. That is, the concept of the polishing composition in the technique disclosed herein includes a polishing liquid (also referred to as a working slurry) supplied to the polishing object and used for polishing the polishing object, and a polishing liquid diluted. Both with the concentrate used as are included. The concentrated solution can also be grasped as a stock solution of a polishing solution. As another example of the polishing liquid containing the polishing composition disclosed herein, there is a polishing liquid obtained by adjusting the pH of the composition.

(Abrasive liquid)
The content of abrasive grains in the polishing liquid is not particularly limited, but is typically 0.01% by weight or more, preferably 0.05% by weight or more. Higher polishing rates can be achieved by increasing the content of abrasive grains. In some embodiments, the content may be 0.10% by weight or more, or 0.15% by weight or more. Further, from the viewpoint of dispersion stability of particles in the polishing composition, the above content is usually preferably 10% by weight or less, preferably 7% by weight or less, more preferably 5% by weight or less, still more preferably. Is 2% by weight or less, for example, 1% by weight or less, and may be 0.7% by weight or less. From the viewpoint of enhancing the haze reducing effect by polishing, in some embodiments, the content may be 0.5% by weight or less, 0.3% by weight or less, or 0.2% by weight or less. It may be 0.19% by weight or less.

The concentration of the water-soluble polymer in the polishing liquid (the total concentration thereof when two or more kinds are contained) is not particularly limited, but usually 0.0001% by weight or more is appropriate, and 0.0005% by weight or more is preferable. .. The concentration may be, for example, 0.0007% by weight or more, 0.001% by weight or more, 0.0015% by weight or more, or 0.002% by weight or more. As the concentration of the water-soluble polymer in the polishing liquid increases, the haze reducing effect of polishing tends to increase. From the viewpoint of reducing LPD, the concentration of the water-soluble polymer is usually 0.2% by weight or less, 0.1% by weight or less, 0.05% by weight or less, and 0. It may be 01% by weight or less. From the viewpoint of facilitating the reduction of LPD even by washing with a lower load, in some embodiments, the concentration may be, for example, 0.005% by weight or less, 0.004% by weight or less, and 0. It may be 003% by weight or less.

The concentration of the surfactant in the polishing liquid (the total concentration thereof when two or more kinds are contained) is not particularly limited, but usually 1 × 10 ^-6 % by weight or more is suitable, and 1 × 10 ^-5 % by weight. The above is preferable. From the viewpoint of enhancing the haze reducing effect by polishing, in some embodiments, the concentration may be, for example, 0.00005% by weight or more, 0.00007% by weight or more, or 0.0001% by weight or more. It may be 0.00015% by weight or more, or 0.00017% by weight or more. Further, from the viewpoint of improving the polishing speed and the like, the concentration is usually 1% by weight or less, preferably 0.1% by weight or less, more preferably 0.01% by weight or less, and 0.005% by weight or less. It may be. In some embodiments, the concentration may be, for example, 0.001% by weight or less, and may be 0.0005% by weight or less.

The more preferable concentration of the surfactant in the polishing liquid may also vary depending on the type of the surfactant. For example, when an anionic surfactant containing a polyoxyalkylene structure is used, the concentration of the surfactant may be, for example, 0.001% by weight or less, or 0.0005% by weight or less.
Further, when a block copolymer of EO and PO such as a PEO-PPO-PEO type triblock copolymer is used as the surfactant, the concentration of the surfactant is, for example, 0.0005% by weight. It may be super, 0.0007% by weight or more, 0.001% by weight or more, or 0.0015% by weight or more.

When the polishing composition disclosed herein contains a basic compound, the concentration of the basic compound in the polishing liquid is not particularly limited. From the viewpoint of improving the polishing speed, the above concentration is usually preferably 0.001% by weight or more, more preferably 0.003% by weight or more, and for example, 0.005% by weight or more of the polishing liquid. can. Further, from the viewpoint of haze reduction and the like, the concentration is preferably less than 0.3% by weight, preferably less than 0.1% by weight, and more preferably less than 0.05% by weight of the polishing liquid. In some embodiments, the concentration may be, for example, less than 0.03% by weight, less than 0.02% by weight, less than 0.01% by weight, less than 0.008% by weight, 0. It may be less than .006% by weight.

(Concentrate)
The polishing composition disclosed herein may be in a concentrated form before being supplied to the object to be polished. The concentrated form is a form of a concentrated solution of the polishing liquid, and can be grasped as a stock solution of the polishing liquid. The polishing composition in such a concentrated form is advantageous from the viewpoint of convenience and cost reduction in production, distribution, storage and the like. The concentration ratio is not particularly limited, and can be, for example, about 2 to 100 times in terms of volume, usually about 5 to 50 times, and can be, for example, about 10 to 40 times.

Such a concentrated liquid can be used in an embodiment in which a polishing liquid (working slurry) is prepared by diluting at a desired timing and the polishing liquid is supplied to an object to be polished. The dilution can be performed, for example, by adding water to the concentrate and mixing.

The content of abrasive grains in the concentrated liquid can be, for example, 10% by weight or less. From the viewpoint of handleability of the concentrated solution, for example, dispersion stability of abrasive grains, filterability, etc., the content of abrasive grains in the concentrated solution is usually preferably 7% by weight or less, more preferably 5% by weight or less. be. Further, from the viewpoint of convenience in manufacturing, distribution, storage, etc., cost reduction, etc., the content of abrasive grains can be, for example, 0.1% by weight or more, preferably 0.5% by weight or more. More preferably, it is 1% by weight or more. In some embodiments, the abrasive grain content may be, for example, 1.5% by weight or more, or 2.5% by weight or more.

(Preparation of polishing composition)
The polishing composition used in the techniques disclosed herein may be a one-dosage form or a multi-dosage form including a two-dosage form. For example, part A containing at least abrasive grains among the constituents of the polishing composition and part B containing at least a part of the remaining components are mixed, and these are mixed and diluted at appropriate timings as necessary. This may be configured so that the polishing liquid is prepared.

The method for preparing the polishing composition is not particularly limited. For example, it is preferable to mix each component constituting the polishing composition using a well-known mixing device such as a blade type stirrer, an ultrasonic disperser, and a homomixer. The mode in which these components are mixed is not particularly limited, and for example, all the components may be mixed at once, or may be mixed in an appropriately set order.

<Use>
The polishing composition in the technique disclosed herein can be applied to the polishing of objects to be polished having various materials and shapes. The material of the object to be polished is, for example, a metal or semi-metal such as silicon, aluminum, nickel, tungsten, copper, tantalum, titanium, stainless steel, or an alloy thereof; glass such as quartz glass, aluminosilicate glass, and glassy carbon. State material; ceramic material such as alumina, silica, sapphire, silicon nitride, tantalum nitride, titanium carbide; compound semiconductor substrate material such as silicon carbide, gallium nitride, gallium arsenide; resin material such as polyimide resin; and the like. Of these, the object to be polished may be made of a plurality of materials.

The polishing composition in the technique disclosed herein can be particularly preferably used for polishing a surface made of silicon, such as a silicon substrate. A typical example of the silicon substrate referred to here is a single crystal silicon wafer, for example, a single crystal silicon wafer obtained by slicing a single crystal silicon ingot.

The polishing composition disclosed herein can be preferably applied to a polishing step of an object to be polished, for example, a polishing step of a silicon wafer. The object to be polished is subjected to general treatments such as wrapping and etching that can be applied to the object to be polished in a process upstream of the polishing step, prior to the polishing step by the polishing composition disclosed herein. You may.

The polishing composition disclosed herein can be preferably used, for example, in polishing an object to be polished, for example, a silicon wafer, which has a surface roughness of 0.01 nm to 100 nm prepared by an upstream process. The surface roughness Ra of the object to be polished can be measured using, for example, a laser scan type surface roughness meter "TMS-3000WRC" manufactured by Schmitt Measurement System Inc. It is effective to use it in final polishing (finish polishing) or immediately before it, and it is particularly preferable to use it in final polishing. Here, the final policing refers to the final policing step in the manufacturing process of the target product, that is, a step in which no further policing is performed after the step.

<Polishing>
The polishing composition disclosed herein can be used for polishing an object to be polished, for example, in an embodiment including the following operations. Hereinafter, a preferred embodiment of a method of polishing an object to be polished, for example, a silicon wafer, using the polishing composition disclosed herein will be described.
That is, a polishing liquid containing any of the polishing compositions disclosed herein is prepared. The preparation of the polishing liquid may include preparing the polishing liquid by subjecting the polishing composition to an operation such as concentration adjustment such as dilution or pH adjustment. Alternatively, the polishing composition may be used as it is as a polishing liquid.

Next, the polishing liquid is supplied to the object to be polished, and polishing is performed by a conventional method. For example, when performing finish polishing of a silicon wafer, typically, the silicon wafer that has undergone the wrapping process is set in a general polishing device, and a polishing liquid is applied to the surface to be polished of the silicon wafer through the polishing pad of the polishing device. Supply. Typically, while continuously supplying the polishing liquid, the polishing pad is pressed against the surface to be polished of the silicon wafer to relatively move, for example, rotate the two. Polishing of the object to be polished is completed through such a polishing step.

The polishing pad used in the polishing step is not particularly limited. For example, a polishing pad such as a polyurethane foam type, a non-woven fabric type, or a suede type can be used. Each polishing pad may or may not contain abrasive grains. Usually, a polishing pad containing no abrasive grains is preferably used.

<Washing>
The object to be polished, which has been polished using the polishing composition disclosed herein, is typically washed. Cleaning can be performed using a suitable cleaning solution. The cleaning liquid to be used is not particularly limited, and for example, SC-1 cleaning liquid, SC-2 cleaning liquid, etc., which are general in the field of semiconductors and the like, can be used. The SC-1 cleaning solution is a mixture of ammonium hydroxide (NH ₄ OH), hydrogen peroxide (H ₂ O ₂ ), and water (H ₂ O). The SC-2 cleaning solution is a mixed solution of hydrogen chloride (HCl), H ₂ O ₂ and H ₂ O. The temperature of the cleaning liquid can be, for example, in the range of room temperature or higher and up to about 90 ° C. The room temperature is typically about 15 ° C to 25 ° C. From the viewpoint of improving the cleaning effect, a cleaning liquid having a temperature of about 50 ° C. to 85 ° C. can be preferably used.

The technique disclosed herein can be particularly preferably applied in polishing a silicon wafer when the polished silicon wafer is treated (cleaned) with an SC-1 cleaning liquid. By treating with the SC-1 cleaning liquid, the surface of the silicon wafer can be thinly etched to remove particles on the surface of the silicon wafer. From the viewpoint of reducing LPD, the degree of etching can be set so that the etching allowance of the silicon wafer is, for example, about 0.1 nm or more. In some embodiments, the etching allowance may be approximately 0.3 nm or more, or approximately 0.5 nm or more. Further, from the viewpoint of suppressing deterioration of the surface roughness due to the treatment with the SC-1 cleaning solution, the etching allowance is preferably 5 nm or less, and more preferably 3 nm or less. According to the polishing composition disclosed herein, even if the etching allowance is less than 2.0 nm, less than 1.5 nm, or less than 1.0 nm, LPD can be effectively reduced by the treatment with the SC-1 cleaning solution.

The magnitude of the load applied to the object to be polished by the treatment with the SC-1 cleaning liquid, that is, the cleaning load can be grasped, for example, by using the degree of deterioration of the surface roughness of the object to be polished by the above treatment as an index. The height of the cleaning load can be adjusted by the composition of the SC-1 cleaning solution, the temperature of the SC-1 cleaning solution, the treatment time (immersion time in the SC-1 cleaning solution), the presence or absence of ultrasonic waves during the treatment, and the like. .. Increasing the cleaning load in the treatment with the SC-1 cleaning liquid is advantageous from the viewpoint of reducing LPD, but tends to further deteriorate the surface roughness due to the above treatment. When the cleaning load is lowered, the deterioration of the surface roughness due to the above treatment tends to be suppressed, but the effect of reducing LPD tends to be insufficient.

According to the techniques disclosed herein, LPD can be effectively reduced even by relatively low load processing. Therefore, the composition of the SC-1 cleaning solution used in the above treatment is, for example, a volume ratio of 29% ammonia water: 31% hydrogen peroxide solution of 1: 0.5 to 1:20, preferably 1: 1 to 1: 1. It can be appropriately set in the range of 10, for example, 1: 2 to 1: 5. In this case, the volume ratio of 29% aqueous ammonia: water may be appropriately set in the range of, for example, 1:10 to 1: 100, preferably 1:20 to 1:50, or 1:25 to 1:40. can. The temperature of the above treatment may be, for example, 80 ° C. or lower, 70 ° C. or lower, or 65 ° C. or lower. The processing time can be set in the range of, for example, 10 seconds to 600 seconds. From the viewpoint of suppressing deterioration of surface roughness, in some embodiments, the treatment time may be, for example, 500 seconds or less, 400 seconds or less, or 300 seconds or less.

In the polishing of silicon wafers, especially in cleaning after finish polishing, the above cleaning conditions are such that the volume ratio of 29% ammonia water, 31% hydrogen peroxide solution and water to the silicon wafer after finish polishing is 1: 3:30. The haze value [ppm] of the surface obtained by performing the cleaning treatment B for 12 minutes with the SC-1 cleaning liquid L ₀ at 60 ° C. contained in the above is H ₀ , and the haze value H ₀ is 5% or more, preferably 10%. As described above, it can be set so as to be more preferably reduced by 20% or more. In some embodiments, the cleaning conditions may be set so that the haze value H ₀ is reduced by 25% or more, even 30% or more. From the viewpoint of achieving both low haze and low LPD at a high level, the cleaning conditions are such that the haze value H ₁ [ppm] after the cleaning is 30% or more, 40% or more, or 50% of the haze value H ₀ . It can be set as above.
The cleaning conditions can be set so that, for example, the cleaning load parameter β represented by the following formula is 95% or less, 90% or less, 80% or less, 75% or less, or 60% or less. Further, the cleaning conditions can be set so that the cleaning load parameter β is, for example, 30% or more, 40% or more, or 50% or more.
β [%] = H ₁ / H ₀ × 100 (II)
A smaller value of the cleaning load parameter β means that the cleaning load is lower in comparison with the cleaning process B. The cleaning load parameter β can be adjusted by adjusting the composition of the SC-1 cleaning solution, the treatment temperature, the treatment time, the presence or absence of ultrasonic waves, and the like. The composition of the SC-1 cleaning solution used for cleaning after polishing may be the same as that of the SC _- 1 cleaning solution L ₀ or LA described above, and is different from these SC-1 cleaning solutions. May be good.

Matters disclosed by this specification include:
(1) A polishing composition containing abrasive grains, a water-soluble polymer, a surfactant, and a basic compound.
The water-soluble polymer has the following formula (I):
α = θ1-θ0 (I)
(Here, θ0 in the above formula (I) is the water contact angle of the SC-1 untreated wafer obtained by applying the aqueous solution of the water-soluble polymer on the surface of the single crystal silicon wafer and then washing with water. Θ1 in the above formula (I) is a room temperature SC-1 cleaning liquid L in which 29% ammonia water, 31% hydrogen peroxide solution and water are contained in the SC-1 untreated wafer at a volume ratio of 1: 2:30. The water contact angle of the SC-1 treated wafer obtained by performing the cleaning treatment A which is treated with _A for 10 seconds.);
A polishing composition comprising a water-soluble polymer WP in which the detergency parameter α represented by is in the range of 1 <α <35.
(2) The polishing composition according to (1) above, wherein the repeating unit constituting the water-soluble polymer WP contains a vinyl alcohol unit.
(3) The polishing composition according to (2) above, wherein the repeating unit constituting the water-soluble polymer WP contains a vinyl alcohol unit and a non-vinyl alcohol unit.
(4) The polishing composition according to (3) above, wherein the total number of moles of the non-vinyl alcohol unit is 1% or more and 30% or less of the total number of moles of the repeating units constituting the water-soluble polymer WP. thing.
(5) The polishing composition according to any one of (1) to ( ⁴ ) above, wherein the Mw of the water-soluble polymer WP is 20 × 104 or less.
(6) The surfactant contains a repeating structure in which oxyalkylene units having 2 or more and 4 or less carbon atoms are continuous, and the average number of moles of oxyalkylene units contained in the repeating structure is larger than 3. , The polishing composition according to any one of (1) to (5) above.
(7) The polishing composition according to any one of (1) to (6) above, which contains an anionic surfactant as the surfactant.
(8) The polishing according to any one of (1) to (7) above, wherein the content of the surfactant is 0.01 part by weight or more and 5 parts by weight or less with respect to 100 parts by weight of the abrasive grains. Composition.
(9) The above-mentioned (1) to (8), wherein the content of the surfactant is 0.001 part by weight or more and 1 part by weight or less with respect to 1 part by weight of the water-soluble polymer. Polishing composition.
(10) Step A of polishing the surface of the silicon wafer using the polishing composition according to any one of (1) to (9) above, and
Step B of processing the silicon wafer with the SC-1 cleaning liquid, and
Is a silicon wafer polishing method that includes in this order.
The process of the above step B is performed by the following formula (II):
β [%] = H ₁ / H ₀ × 100 (II)
(Here, H ₀ in the above formula (II) is a volume ratio of 29% ammonia water, 31% hydrogen hydrogen water and water to the silicon wafer obtained in the above step A at 1: 3:30. Represents the haze value [ppm] of the surface obtained by performing the cleaning treatment B for 12 minutes with the SC-1 cleaning liquid L ₀ at 60 ° C. contained in, and H ₁ in the above formula (II) is obtained by the above step A. It represents the haze value [ppm] of the surface obtained by processing the silicon wafer obtained in the above step B.);
A silicon wafer polishing method performed under conditions set so that the cleaning load parameter β represented by is 80% or less.

Hereinafter, some examples of the present invention will be described, but the present invention is not intended to be limited to those shown in such examples. In the following description, "part" and "%" are based on weight unless otherwise specified.

(1) Preparation of Polishing Composition Examples 1 to 3 and Comparative Examples 1 to 3 having a pH of 10.0 by mixing the following materials in deionized water so as to have the composition shown in Table 1. Each polishing composition was prepared. In the above mixing, the mixing temperature was about 20 ° C. and the mixing time was about 5 minutes.

(material)
・ Abrasive grains (colloidal silica, BET diameter: 25 nm)
-Water-soluble polymer (In Table 1, "hydrophobic-modified PVA" represents a random copolymer having a vinyl alcohol unit and an n-propyl vinyl ether unit in a molar ratio of 85:15, and represents "poly (VA-co-". "VP)" represents a random copolymer having a vinyl alcohol unit and an N-vinylpyrrolidone unit in a molar ratio of 90:10, "HEC" represents hydroxyethyl cellulose, and "PVP" is the weight of N-vinylpyrrolidone alone. Represents coalescence.)
-Basic compound (29% aqueous ammonia)
-Surfactant (In Table 1, "A" represents ammonium polyoxyethylene lauryl ether ammonium sulfate having an average addition molar number of ethylene oxide (EO) of 18, and "B" represents PEO-PPO-PEO having an Mw of 9000. Represents a block copolymer.)
The characteristics of each polishing composition are summarized in Table 1.

The detergency parameter α of each water-soluble polymer was determined according to the method for measuring the detergency parameter α described above.

The Mw of each water-soluble polymer was determined by GPC under the following conditions.
(GPC condition>
Column: TSKgel GMPWx1 + TSKgel GMPWx1
Eluent: 100 mM aqueous sodium nitrate solution / acetonitrile = 10-8 / 0-2
Sample concentration: 0.1%
Flow rate: 1.0 mL / min Injection volume: 200 μL
Standard substance: Polyethylene oxide Column temperature: 40 ° C
Detector: Differential Refractometer (RI)

The average number of moles of ethylene oxide added to the surfactant B was calculated based on the molecular structure.

(2) Polishing of silicon substrate (preliminary polishing)
Using a polishing solution containing 1.00% colloidal silica with a BET diameter of 35 nm and 0.07% potassium hydroxide (KOH) and the balance being water, a single crystal silicon wafer as an object to be polished was polished under the following polishing conditions I. Polished with. The single crystal silicon wafer is a commercially available single crystal silicon wafer having a diameter of 300 mm that has been wrapped and etched (conduction type: P type, crystal orientation: <100>, resistivity: 1Ω · cm or more and less than 100Ω · cm, COP. Free) was used.

[Polishing condition I]
Polishing equipment: Single-wafer polishing machine manufactured by Okamoto Machine Tool Co., Ltd., model "PNX-332B"
Polishing load: 20 kPa
Platen (surface plate) rotation speed: 20 rpm
Head (carrier) rotation speed: 20 rpm
Polishing pad: Made by Fujibo Ehime Co., Ltd., POLYPAS (registered trademark) FP55 (nonwoven fabric type, thickness about 2 mm, density about 0.3 g / cm ³ , compressibility about 7%, compressibility about 90%, hardness about 50 ° )
Abrasive liquid supply rate: 1 L / min Abrasive liquid temperature: 20 ° C
Surface plate cooling water temperature: 20 ° C
Polishing time: 2 minutes

(Finish polishing)
Next, the polishing composition prepared in (1) above was used as it was as a polishing liquid, and the single crystal silicon wafer pre-polished above was polished under the following polishing condition II.

[Polishing condition II]
Polishing equipment: Single-wafer polishing machine manufactured by Okamoto Machine Tool Co., Ltd., model "PNX-332B"
Polishing load: 15 kPa
Platen (surface plate) rotation speed: 30 rpm
Head (carrier) rotation speed: 30 rpm
Polishing pad: Made by Fujibo Ehime Co., Ltd., POLYPAS (registered trademark) 27NX (swed type, thickness about 1.5 mm, density about 0.4 g / cm ³ , compressibility about 20%, compressibility about 90%, hardness about 40 °, average opening diameter of about 45 μm, opening rate of about 25%)
Polishing liquid supply rate: 2L / min Polishing liquid temperature: 20 ° C
Surface plate cooling water temperature: 20 ° C
Polishing time: 4 minutes

(Washing)
The polished silicon wafer was removed from the polishing apparatus and cleaned under the following cleaning condition A (normal condition) or cleaning condition B (low load condition).

[Cleaning condition A]
A cleaning tank equipped with an ultrasonic oscillator having a frequency of 950 kHz and a rinse tank equipped with an ultrasonic oscillator having a frequency of 950 kHz were prepared. The SC-1 cleaning solution _L0 , which is a mixture of 29% ammonia water, 31% hydrogen peroxide solution, and deionized water at a volume ratio of 1: 3:30, was housed in the cleaning tank and maintained at 60 ° C. Ultrapure water was contained in the rinse tank and kept at 25 ° C. With the ultrasonic transmitters attached to the cleaning tank and the rinsing tank operated, the polished silicon wafer was immersed in the cleaning tank for 12 minutes, then immersed in the rinsing tank for 2 minutes, and then. It was pulled up and dried in an isopropyl alcohol (IPA) atmosphere.

[Cleaning condition B]
The SC-1 cleaning liquid L ₀ was housed in a cleaning tank similar to that used under cleaning condition A and maintained at 60 ° C. Ultrapure water was placed in a rinsing tank similar to that used in cleaning condition A and kept at 25 ° C. With the ultrasonic transmitters attached to the cleaning tank and the rinsing tank operated, the polished silicon wafer was immersed in the cleaning tank for 4 minutes, then in the rinsing tank for 2 minutes, and then. It was pulled up and dried in an IPA atmosphere.

(3) Evaluation The following evaluation was performed on the silicon wafer obtained in (2) above.

(Measurement of number of defects)
A wafer inspection device (manufactured by KLA Tencor Co., Ltd., trade name "Surfscan SP2XP") was used to count the number of defects (particles) having a size of 61 nm or more existing on the surface of the silicon wafer after cleaning. Based on the number of defects counted (LPD-N number), the number of defects was evaluated in the following four stages, and the results are shown in Table 1. The LPD-N is an abbreviation for Light Point Defect Non-cleanable.
A: LPD-N number is less than 50 B: LPD-N number is 50 or more and less than 100 C: LPD-N number is 100 or more and less than 200 D: LPD-N number is 200 or more. If the measurement upper limit is exceeded, it is evaluated as "D".

(Haze measurement)
The haze [ppm] was measured in DWO mode using a wafer inspection device (manufactured by KLA Tencor, trade name "Surfscan SP2XP"). The obtained results are shown in Table 1 after being converted into a relative value (haze ratio) in which the haze value after washing under the washing condition A for Comparative Example 1 is 100%. When the haze ratio is less than 100%, the haze reduction effect can be significantly confirmed.

As shown in Table 1, according to Examples 1 to 3 in which finish polishing was performed using a polishing composition containing a water-soluble polymer WP having a detergency parameter α greater than 1 and less than 35, cleaning condition A. The particles could be effectively removed not only when the above was applied but also when the cleaning condition B was applied. Then, by applying the cleaning condition B, deterioration of the surface roughness during cleaning was suppressed as compared with the case where the cleaning condition A was applied, and as a result, a remarkable haze reducing effect was obtained.
On the other hand, in Comparative Example 1 in which the value of the detergency parameter α was too small, the particle removability was low according to the cleaning condition B, and the defects were significantly increased as compared with the cleaning condition A. Further, in Comparative Example 2 in which the value of the detergency parameter α was too large, the haze reduction by polishing was insufficient, and a low haze surface could not be obtained regardless of the high or low cleaning load. In Comparative Example 3 in which the surfactant was removed from the composition of Examples 2 and 3, the effect was lower than that in Examples 2 and 3.

Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of claims. The techniques described in the claims include various modifications and modifications of the specific examples illustrated above.

Claims (10)

A polishing composition containing abrasive grains, a water-soluble polymer, a surfactant, and a basic compound.
The water-soluble polymer has the following formula (I):
α = θ1-θ0 (I)
(Here, θ0 in the formula (I) is the water contact angle of the SC-1 untreated wafer obtained by applying the aqueous solution of the water-soluble polymer to the surface of the single crystal silicon wafer and then washing with water. Θ1 in the formula (I) is a room temperature SC-1 cleaning liquid L containing 29% ammonia water, 31% hydrogen peroxide water and water in a volume ratio of 1: 2:30 in the pre-treated wafer. The water contact angle of the SC-1 treated wafer obtained by performing the cleaning treatment A which is treated with _A for 10 seconds.);
A polishing composition comprising a water-soluble polymer WP in which the detergency parameter α represented by is in the range of 1 <α <35. The polishing composition according to claim 1, wherein the repeating unit constituting the water-soluble polymer WP contains a vinyl alcohol unit. The polishing composition according to claim 2, wherein the repeating unit constituting the water-soluble polymer WP contains a vinyl alcohol unit and a non-vinyl alcohol unit. The polishing composition according to claim 3, wherein the total number of moles of the non-vinyl alcohol unit is 1% or more and 30% or less of the total number of moles of the repeating units constituting the water-soluble polymer WP. The polishing composition according to any one of claims 1 to ⁴ , wherein the water-soluble polymer WP has a weight average molecular weight of 20 × 104 or less. Claimed that the surfactant includes a repeating structure in which oxyalkylene units having 2 or more and 4 or less carbon atoms are continuous, and the average number of moles of oxyalkylene units contained in the repeating structure is larger than 3. The polishing composition according to any one of 1 to 5. The polishing composition according to any one of claims 1 to 6, which contains an anionic surfactant as the surfactant. The polishing composition according to any one of claims 1 to 7, wherein the content of the surfactant is 0.01 part by weight or more and 5 parts by weight or less with respect to 100 parts by weight of the abrasive grains. The polishing composition according to any one of claims 1 to 8, wherein the content of the surfactant is 0.001 part by weight or more and 1 part by weight or less with respect to 1 part by weight of the water-soluble polymer. .. A step of polishing the surface of a silicon wafer using the polishing composition according to any one of claims 1 to 9.
Step B of treating the silicon wafer with the SC-1 cleaning liquid, and
Is a silicon wafer polishing method that includes in this order.
The process of the step B is performed by the following formula (II):
β [%] = H ₁ / H ₀ × 100 (II)
(Here, H ₀ in the formula (II) is a volume ratio of 29% ammonia water, 31% hydrogen hydrogen water, and water to the silicon wafer obtained in the step A at a volume ratio of 1: 3:30. Represents the haze value [ppm] of the surface obtained by performing the cleaning treatment B for 12 minutes with the SC-1 cleaning liquid L ₀ at 60 ° C. contained in the above formula (II), and H ₁ in the above formula (II) is obtained by the above step A. It represents the haze value [ppm] of the surface obtained by processing the silicon wafer obtained in the step B.);
A silicon wafer polishing method performed under conditions set so that the cleaning load parameter β represented by is 80% or less.