WO2018025656A1

WO2018025656A1 - Production method for silicon wafer rough-polishing composition, silicon wafer rough-polishing composition set, and silicon wafer polishing method

Info

Publication number: WO2018025656A1
Application number: PCT/JP2017/026406
Authority: WO
Inventors: 雄彦村瀬; 誠田畑; 恵谷口; 公亮土屋
Original assignee: 株式会社フジミインコーポレーテッド
Priority date: 2016-08-02
Filing date: 2017-07-21
Publication date: 2018-02-08
Also published as: TW201815906A; JPWO2018025656A1; JP7026043B2

Abstract

The present invention provides a production method for a silicon wafer rough-polishing composition, said method being capable of simultaneously providing excellent stability and the advantage of a concentrated liquid, and enabling improvement in edge roll-off. The production method for a silicon wafer rough-polishing composition according to the present invention is a method for producing a silicon wafer rough-polishing composition that contains abrasive particles, a basic compound, and a water-soluble polymer. This production method comprises: a step for preparing liquid A that contains the abrasive particles and the basic compound; a step for preparing liquid B that contains, as the water-soluble polymer, a water-soluble polymer P1 having a radius of gyration of at least 100 nm; and a step for mixing liquid A and liquid B.

Description

Method for producing silicon wafer rough polishing composition, silicon wafer rough polishing composition set, and silicon wafer polishing method

The present invention relates to a method for producing a polishing composition, a polishing composition set, and a polishing method. Specifically, the present invention relates to a method for producing a polishing composition used for rough polishing of a silicon wafer, a polishing composition set, and a method for polishing a silicon wafer using the polishing composition.
This application claims priority based on Japanese Patent Application No. 2016-152325 filed on Aug. 2, 2016, the entire contents of which are incorporated herein by reference.

Generally, the surface of a silicon substrate used for manufacturing a semiconductor product is finished to a high-quality mirror surface through a lapping process and a polishing process. The polishing process typically includes a preliminary polishing process (rough polishing process) and a final polishing process (finish polishing process). The polishing step is performed using a polishing composition (polishing slurry). Patent document 1 is mentioned as a prior art document which discloses the constituent for polish used for polish of a silicon substrate. In addition, this type of polishing composition may be in a concentrated form before being supplied to the object to be polished from the viewpoint of convenience, cost reduction, and the like during production, distribution, storage, and the like. That is, the polishing composition may be in the form of a concentrated concentrate of polishing liquid. The prepared concentrated liquid is diluted with water and used for polishing. Patent documents 2 and 3 are mentioned as literature which discloses this kind of prior art. Patent Document 4 is a document disclosing the radius of inertia of hydroxycellulose used in the polishing composition.

Japanese Patent Application Publication No. 2014-216464 Japanese Patent Application Publication No. 2012-89862 Japanese Patent Application Publication No. 2015-155523 Japanese Patent Application Publication No. 2015-124231

As a result of examining the performance improvement of the composition for rough polishing of a silicon wafer, the present inventors have used a water-soluble polymer having an inertial radius greater than or equal to a predetermined value after polishing, as shown in Examples below. It was found that the phenomenon of undesirably decreasing the thickness of the outer periphery (near the edge), that is, edge roll-off can be improved. However, a water-soluble polymer having a large inertial radius tends to be less stable when the polishing composition is stored as a concentrate. Specifically, since the concentrated liquid contains components such as abrasive grains and water-soluble polymers at a higher concentration than when used, there is a risk that good stability such as separation and aggregation of the contained components may not be obtained. is there.

The present invention has been made in view of the above circumstances, and is a composition for rough polishing of silicon wafers that can achieve both the advantages of the concentrate and excellent stability, and can improve edge roll-off. It aims at providing the manufacturing method of a thing. Another related object is to provide a composition set for rough polishing a silicon wafer and to provide a method for polishing a silicon wafer.

According to the present invention, there is provided a method for producing a composition for rough polishing a silicon wafer containing abrasive grains, a basic compound and a water-soluble polymer. The production method includes: a step of preparing a liquid A containing the abrasive grains and the basic compound; and a step of preparing a liquid B containing a water-soluble polymer P1 having an inertial radius of 100 nm or more as the water-soluble polymer. And a step of mixing the liquid A and the liquid B. The polishing composition obtained by such a method can improve edge roll-off in polishing a silicon substrate by including the water-soluble polymer P1 having a predetermined or larger inertia radius. Moreover, the polishing composition before completion, in other words, before use, is a multi-drug type having a liquid A and a liquid B. Concentration such as convenience and cost reduction is achieved by increasing the concentration of each liquid (concentrated liquid). You can enjoy the benefits of liquid. In addition, since the abrasive grains and the water-soluble polymer P1 are separately stored in the liquid A and the liquid B, an event in which the dispersion of the water-soluble polymer P1 is hindered by the presence of the abrasive grains can be avoided. As a result, the polishing composition before completion shows excellent stability in the state of liquid A and liquid B. Therefore, according to the present invention, it is possible to produce a silicon wafer rough polishing composition that is excellent in stability and can improve edge roll-off while enjoying the advantages of the concentrate.

Further, according to the present invention, there is provided a polishing composition set for producing a silicon wafer rough polishing composition containing abrasive grains, a basic compound and a water-soluble polymer. Such a polishing composition set includes a liquid A containing the abrasive grains and the basic compound, and a liquid B containing a water-soluble polymer P1 having an inertia radius of 100 nm or more as the water-soluble polymer. According to such a configuration, the liquid A and the liquid B each have excellent stability while enjoying the advantages of the concentrated liquid when used as a concentrated liquid before use, for example, during storage. Then, liquid A and liquid B are mixed at an appropriate timing to obtain a polishing composition (polishing slurry), and by using this, the edge roll-off of the silicon substrate can be improved. The advantages of the concentrated liquid are convenience and cost reduction.

In addition, according to the present invention, a silicon wafer polishing method including a rough polishing step and a final polishing step is provided. This polishing method includes a step of preparing a rough polishing composition used in the rough polishing step before the rough polishing step. The step of preparing the rough polishing composition includes: a step of preparing a solution A containing abrasive grains and a basic compound; and a step of preparing a solution B containing a water-soluble polymer P1 having an inertia radius of 100 nm or more. And a step of mixing the liquid A and the liquid B. According to this method, the polishing composition before use can be made into a concentrated solution having excellent stability in a state where the polishing composition is separated into the liquid A and the liquid B. Moreover, edge roll-off of the silicon substrate can be improved by performing rough polishing using the polishing composition.

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

According to the present specification, a method for producing a polishing composition, a polishing composition set for producing the polishing composition, and a method for polishing a silicon wafer using the polishing composition are provided. Hereinafter, the polishing composition produced by the method disclosed herein will be described first, and then the production method, the polishing composition set, and the polishing method using the polishing composition will be described in this order.

<Polishing composition>
(Abrasive grains)
The polishing composition disclosed herein contains abrasive grains. The material and properties of the abrasive grains are not particularly limited, and can be appropriately selected according to the purpose of use and the mode of use. Examples of the abrasive grains include inorganic particles, organic particles, and organic-inorganic composite particles. Specific examples of the inorganic particles include 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, oxide particles such as bengara particles; Examples thereof include 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. Specific examples of the organic particles include polymethyl methacrylate (PMMA) particles, poly (meth) acrylic acid particles, and polyacrylonitrile particles. Such an abrasive grain may be used individually by 1 type, and may be used in combination of 2 or more type. In addition, (meth) acrylic acid is the meaning which points out acrylic acid and methacrylic acid comprehensively.

As the abrasive, inorganic particles are preferable, and particles made of metal or metalloid oxide are particularly preferable. A particularly preferable abrasive grain in the technology disclosed herein includes silica particles. The technique disclosed here can be preferably implemented, for example, in a mode in which the abrasive grains are substantially composed of silica particles. Here, “substantially” means that 95% by weight or more of the particles constituting the abrasive grains are silica particles, preferably 98% by weight or more, more preferably 99% by weight or more are silica particles, 100% by weight of the particles constituting the abrasive grains may be silica particles.

Specific examples of the silica particles include colloidal silica, fumed silica, precipitated silica and the like. Silica particles can be used alone or in combination of two or more. Colloidal silica is particularly preferable because scratches are hardly generated on the surface of the object to be polished and good polishing performance can be exhibited. The polishing performance is, for example, performance for reducing the surface roughness. As the colloidal silica, for example, colloidal silica produced using water glass (Na silicate) as a raw material by an ion exchange method or alkoxide colloidal silica can be preferably used. The alkoxide colloidal silica refers to colloidal silica produced by hydrolysis condensation reaction of alkoxysilane. Colloidal silica can be used alone or in combination of two or more.

The true specific gravity of silica constituting the silica particles is preferably 1.5 or more, more preferably 1.6 or more, and even more preferably 1.7 or more. As the true specific gravity of silica increases, the polishing rate tends to increase. From this viewpoint, silica particles having a true specific gravity of 2.0 or more, such as 2.1 or more, are particularly preferable. The upper limit of the true specific gravity of silica is not particularly limited, but is typically 2.3 or less, for example, 2.2 or less. As the true specific gravity of silica, a measured value by a liquid substitution method using ethanol as a substitution liquid can be adopted.

The average primary particle diameter of the abrasive grains disclosed herein is not particularly limited. From the viewpoint of polishing rate and the like, the average primary particle size is suitably 5 nm or more, preferably 10 nm or more, more preferably 30 nm or more, still more preferably 40 nm or more, and particularly preferably 45 nm or more. In a particularly preferred embodiment, the average primary particle diameter is, for example, 50 nm or more. The abrasive grains are typically silica particles. From the viewpoint of preventing scratches and the like, the average primary particle diameter of the abrasive is suitably about 200 nm or less, preferably 100 nm or less, more preferably 80 nm or less, still more preferably 70 nm or less, particularly preferably 60 nm. It can be:
In addition, in this specification, the average primary particle diameter means a BET diameter [nm] = 6000 / (true density [g / cm ³ ] × BET value [m ² ] from a specific surface area (BET value) measured by the BET method. / G]) is the particle diameter calculated by the equation. For example, in the case of silica particles, the BET diameter can be calculated from BET diameter [nm] = 2727 / BET value [m ² / g]. The specific surface area can be measured using, for example, a surface area measuring device manufactured by Micromeritex Corporation, a 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 bowl shape, a confetti shape, and a rugby ball shape. The peanut shape is that of a peanut shell. For example, abrasive grains in which many of the particles have a peanut shape can be preferably used.

Although not particularly limited, the average value of the major axis / minor axis ratio (average aspect ratio) of the abrasive grains is theoretically 1.0 or more, preferably 1.05 or more, more preferably 1.1 or more. It is. By increasing the average aspect ratio, a higher polishing rate can be achieved. The average aspect ratio of the abrasive grains is preferably 3.0 or less, more preferably 2.0 or less, and still more preferably 1.5 or less, from the viewpoint of reducing scratches.

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

The content of the abrasive grains in the polishing composition disclosed herein is not particularly limited, preferably 0.05% by weight or more, more preferably 0.1% by weight or more, and further preferably 0.3% by weight or more. It is. In a further preferred embodiment, the content of the abrasive grains is, for example, 0.5% by weight or more. Higher polishing rates can be achieved by increasing the abrasive content. Further, from the viewpoint of removability from the polishing object, the content is suitably 10% by weight or less, preferably 7% by weight or less, more preferably 5% by weight or less, and further preferably 3% by weight or less. It is. In a more preferred embodiment, the content of the abrasive grains is, for example, 2% by weight or less.

(Water-soluble polymer P1)
The polishing composition disclosed herein includes a water-soluble polymer P1 having an inertia radius of 100 nm or more. By using the water-soluble polymer P1 having the inertial radius, the edge roll-off is improved. The reason is not particularly limited, but the water-soluble polymer P1 having a predetermined or larger inertia radius contained in the polishing composition (polishing slurry) strongly adsorbs to the end of the substrate to be polished. It is presumed that an increase in edge roll-off (end sagging) is suppressed by avoiding excessive polishing. The inertial radius of the water-soluble polymer P1 is the size of one molecule of the water-soluble polymer P1 in the aqueous solution, and can be determined mainly by the hydrophilicity, molecular weight, etc. of the polymer P1. From the viewpoint of improving edge roll-off, the radius of inertia of the water-soluble polymer P1 is preferably 105 nm or more, more preferably 120 nm or more, and particularly preferably 140 nm or more. The upper limit of the radius of inertia of the water-soluble polymer P1 is not particularly limited, and should be about 500 nm or less from the viewpoint of the stability and concentration efficiency of the B liquid used as the water-soluble polymer P1-containing liquid in polishing composition production. Is preferably 300 nm or less, more preferably 250 nm or less, and even more preferably 220 nm or less. The inertia radius of the water-soluble polymer P1 may be, for example, 150 nm or less and 120 nm or less. In addition, the inertial radius of the water-soluble polymer in this specification is measured by the method described in Examples described later.

The type of the water-soluble polymer P1 contained in the polishing composition disclosed herein is not particularly limited, and can be appropriately selected from water-soluble polymer species known in the field of polishing compositions. The water-soluble polymer P1 can be used alone or in combination of two or more. Examples of the water-soluble polymer P1 include cellulose derivatives, starch derivatives, polymers containing oxyalkylene units, polymers containing nitrogen atoms, polyvinyl alcohol and the like. Among these, from the viewpoint of improving flatness, cellulose derivatives and starch derivatives are preferable, and cellulose derivatives are more preferable.

Cellulose derivatives are polymers containing β-glucose units as the main repeating unit. Specific examples of the cellulose derivative include hydroxyethyl cellulose (HEC), hydroxypropyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, ethyl cellulose, ethyl hydroxyethyl cellulose, carboxymethyl cellulose and the like. Of these, HEC is preferable.

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

Polymers containing oxyalkylene units include polyethylene oxide (PEO), block copolymers of ethylene oxide (EO) and propylene oxide (PO) or butylene oxide (BO), and random copolymerization of EO and PO or BO. Examples include coalescence. Among these, a block copolymer of EO and PO or a random copolymer of EO and PO is preferable. The block copolymer of EO and PO may be a diblock body, a triblock body or the like including a PEO block and a polypropylene oxide (PPO) block. Examples of the triblock body include a PEO-PPO-PEO type triblock body and a PPO-PEO-PPO type triblock body. Among these, a PEO-PPO-PEO type triblock body is more preferable.
In the block copolymer or random copolymer of EO and PO, the molar ratio [EO / PO] of EO and PO constituting the copolymer is from the viewpoint of solubility in water, detergency, and the like. It is preferably larger than 1, more preferably 2 or more, and further preferably 3 or more. In a more preferred embodiment, the molar ratio [EO / PO] is, for example, 5 or more.

As the polymer containing a nitrogen atom, both a polymer containing a nitrogen atom in the main chain and a polymer having a nitrogen atom in a side chain functional group (pendant group) can be used. By using a polymer containing nitrogen atoms, the surface roughness of the substrate can be improved. Examples of the polymer containing a nitrogen atom in the main chain include homopolymers and copolymers of N-acylalkylenimine type monomers. Specific examples of the N-acylalkyleneimine monomer include N-acetylethyleneimine, N-propionylethyleneimine and the like. Examples of the polymer having a nitrogen atom in the pendant group include a polymer containing an N-vinyl type monomer unit. For example, homopolymers and copolymers of N-vinylpyrrolidone can be employed. In the technology disclosed herein, at least one of a homopolymer and a copolymer of N-vinylpyrrolidone obtained by polymerizing N-vinylpyrrolidone at a ratio of 50 mol% or more (hereinafter also referred to as “PVP”). Preferably used.

When using polyvinyl alcohol as the water-soluble polymer P1, the saponification degree of the polyvinyl alcohol is not particularly limited.

In the technique disclosed herein, the molecular weight of the water-soluble polymer P1 is not particularly limited. From the viewpoint of concentration efficiency and the like, the weight average molecular weight (Mw) of the water-soluble polymer P1 can be about 300 × 10 ⁴ or less, and is preferably 150 × 10 ⁴ or less. The Mw may be, for example, 130 × 10 ⁴ or less and 110 × 10 ⁴ or less. Further, from the viewpoint of protecting the substrate surface and improving the polishing performance, Mw is suitably 1 × 10 ⁴ or more, preferably 10 × 10 ⁴ or more, more preferably 20 × 10 ⁴ or more. In a more preferred embodiment, the Mw is, for example, 50 × 10 ⁴ or more, and further 80 × 10 ⁴ or more. The Mw may be, for example, 110 × 10 ⁴ or more and 130 × 10 ⁴ or more. The Mw can be particularly preferably adopted for the cellulose derivative. Examples of the cellulose derivative include HEC.

The relationship between the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the water-soluble polymer P1 is not particularly limited. From the viewpoint of preventing the occurrence of aggregates, for example, the molecular weight distribution [Mw / Mn] is preferably 10.0 or less, and more preferably 7.0 or less.

As Mw and Mn of the water-soluble polymer P1, values based on an aqueous gel permeation chromatography (GPC) (aqueous, polyethylene oxide equivalent) can be adopted. The same applies to the water-soluble polymer P2 described later.

The content of the water-soluble polymer P1 in the polishing composition is suitably 1 × 10 ⁻⁵ wt% or more, for example, 5 × 10 ⁻⁵ wt% or more, from the viewpoint of improving polishing performance and surface quality. Preferably, it is 1 × 10 ⁻⁴ wt% or more. In a preferred embodiment, the content of the water-soluble polymer P1 is, for example, 2 × 10 ⁻⁴ wt% or more. The upper limit of the content of the water-soluble polymer P1 in the polishing composition can be, for example, 1% by weight or less. From the viewpoint of stability at the concentrate stage, polishing rate, detergency, etc., the content of the water-soluble polymer P1 is preferably 0.1% by weight or less, more preferably 0.05% by weight or less, and still more preferably It is 0.02% by weight or less, particularly preferably 0.01% by weight or less. In a particularly preferred embodiment, the content of the water-soluble polymer P1 is, for example, 0.005% by weight or less, typically 0.001% by weight or less. The concentrated liquid is typically B liquid.

Further, the content of the water-soluble polymer P1 in the polishing composition disclosed herein can also be specified by a relative relationship with the abrasive grains contained in the polishing composition. Specifically, the content of the water-soluble polymer P1 in the polishing composition is suitably 0.001 part by weight or more with respect to 100 parts by weight of the abrasive grains, from the viewpoint of improving edge roll-off, etc. The amount is preferably 0.005 parts by weight or more, more preferably 0.01 parts by weight or more, and still more preferably 0.015 parts by weight or more. From the viewpoint of stability and polishing rate, the content of the water-soluble polymer P1 is suitably 10 parts by weight or less, preferably 1 part by weight or less, based on 100 parts by weight of the abrasive grains. Preferably it is 0.5 weight part or less, More preferably, it is 0.3 weight part or less.

(Water-soluble polymer P2)
In a preferred embodiment of the technology disclosed herein, the polishing composition further includes a water-soluble polymer P2 having an inertial radius of less than 100 nm in addition to the water-soluble polymer P1 having an inertial radius of 100 nm or more. Unlike the water-soluble polymer P1, the water-soluble polymer P2 is a component that plays a role in protecting the substrate surface such as etching suppression and contributes to reducing the surface roughness. The radius of inertia of the water-soluble polymer P2 is preferably less than 90 nm, more preferably less than 70 nm, and still more preferably less than 50 nm from the viewpoint of stability, concentration efficiency, and the like. In a further preferred embodiment, the inertial radius of the water-soluble polymer P2 is, for example, less than 30 nm, typically less than 5 nm. The lower limit of the inertial radius of the water-soluble polymer P2 is not particularly limited, and may be 0.1 nm or more, for example, 1 nm or more.

The type of the water-soluble polymer P2 is not particularly limited, and can be appropriately selected from water-soluble polymer species known in the field of polishing compositions. Examples of the water-soluble polymer P2 include cellulose derivatives exemplified as the water-soluble polymer P1, starch derivatives, polymers containing oxyalkylene units, polymers containing nitrogen atoms, and polyvinyl alcohol. From the viewpoint of reducing the surface roughness, the water-soluble polymer P2 is preferably a polymer other than the cellulose derivative and / or the starch derivative, and more preferably a polymer containing a nitrogen atom. The polymer other than the cellulose derivative and / or starch derivative is typically a polymer other than the cellulose derivative. As specific examples of cellulose derivatives, starch derivatives, polymers containing oxyalkylene units, polymers containing nitrogen atoms, and polyvinyl alcohol, one or more of those exemplified as the water-soluble polymer P1 can be used. Among them, a polymer containing a nitrogen atom in the main chain and a polymer having a nitrogen atom in the side chain functional group (pendant group) are preferable, and a polymer containing an N-vinyl type monomer unit is more preferable. Among these, N-vinylpyrrolidone homopolymers and copolymers (typically PVP) are particularly preferred.

The molecular weight of the water-soluble polymer P2 is not particularly limited. The weight average molecular weight (Mw) of the water-soluble polymer P2 can be about 300 × 10 ⁴ or less, and is suitably 150 × 10 ⁴ or less, for example, 50 × 10 ⁴ or less. From the viewpoint of stability and the like, the Mw may be 30 × 10 ⁴ or less, for example, 5 × 10 ⁴ or less. Further, from the viewpoint of improving the protection of the substrate surface, Mw is suitably 1 × 10 ⁴ or more, more preferably 2 × 10 ⁴ or more, and further preferably 3 × 10 ⁴ or more. The above Mw can be particularly preferably employed for homopolymers and copolymers (typically PVP) of N-vinylpyrrolidone.

The relationship between the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the water-soluble polymer P2 is not particularly limited. From the viewpoint of preventing the occurrence of aggregates, for example, the molecular weight distribution [Mw / Mn] is preferably 10.0 or less, more preferably 7.0 or less, and even more preferably 5.0 or less. A value of 4.0 or less is particularly preferred, and a value of 3.0 or less is most preferred.

In the technique disclosed herein, when the water-soluble polymer P1 and the water-soluble polymer P2 are used in combination as the water-soluble polymer, the mixing ratio of the water-soluble polymer P1 and the water-soluble polymer P2 is particularly For example, the water-soluble polymer P1: water-soluble polymer P2 is suitably 1: 9 to 9: 1, preferably 3: 7 to 8: 2, more preferably 5: 5 to 7: 3. The water-soluble polymer P1 is a cellulose derivative such as HEC, and the water-soluble polymer P2 is a polymer containing an N-vinyl type monomer unit such as PVP.

In the polishing composition according to one embodiment, the content of the water-soluble polymer P2 is less than 100% by weight when the content of the water-soluble polymer P1 is 100% by weight, and is preferable from the viewpoint of stability. Is less than 80% by weight, more preferably less than 70% by weight. In a more preferred embodiment, the content of the water-soluble polymer P2 is, for example, less than 60% by weight. Further, from the viewpoint of reducing the surface roughness, the content of the water-soluble polymer P2 can be about 10% by weight or more when the content of the water-soluble polymer P1 is 100% by weight, and 30% by weight. % Or more is suitable, and preferably 50% by weight or more. In the technique disclosed here, the content of the water-soluble polymer other than the water-soluble polymer P1 is the content of the water-soluble polymer P1, whether or not the polishing composition contains the water-soluble polymer P2. When the amount is 100% by weight, it can be less than about 200% by weight, for example, less than 150% by weight, and more preferably less than 100% by weight. From the viewpoint of stability, the content of the water-soluble polymer other than the water-soluble polymer P1 is preferably less than 80% by weight, more preferably 70% by weight when the content of the water-soluble polymer P1 is 100% by weight. %, Even less than 50% by weight, for example, less than 30% by weight, or less than 10% by weight, for example, 1% by weight or less, specifically 0 to 1% by weight. In a more preferred embodiment, the content of the water-soluble polymer other than the water-soluble polymer P1 is, for example, less than 60% by weight.

(Basic compound)
The polishing composition disclosed herein contains a basic compound. In the present specification, the basic compound refers to a compound having a function of dissolving in water and increasing the pH of an aqueous solution. As the basic compound, an organic or inorganic basic compound containing nitrogen, an alkali metal hydroxide, an alkaline earth metal hydroxide, various carbonates, bicarbonates, or the like can be used. Examples of basic compounds containing nitrogen include quaternary ammonium compounds, quaternary phosphonium compounds, ammonia, amines and the like. The amine is preferably a water-soluble amine. Such basic compounds can be used singly or in combination of two or more.

Specific examples of the alkali metal hydroxide include potassium hydroxide and sodium hydroxide. Specific examples of the carbonate or bicarbonate include ammonium bicarbonate, ammonium carbonate, potassium bicarbonate, potassium carbonate, sodium bicarbonate, 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, anhydrous piperazine , 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 hydroxide 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 quaternary ammonium salt is typically a strong base. 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 Among these preferred examples, the anion is OH ^- a is a quaternary ammonium salt, i.e., include quaternary ammonium hydroxide. Specific examples of quaternary ammonium hydroxide include hydroxides such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetrapentylammonium hydroxide, and tetrahexylammonium hydroxide. Tetraalkylammonium hydroxide; hydroxyalkyltrialkylammonium hydroxide such as 2-hydroxyethyltrimethylammonium hydroxide (also referred to as choline); and the like. Of these, tetraalkylammonium hydroxide is preferable, and tetramethylammonium hydroxide (TMAH) is particularly preferable.

The polishing composition disclosed herein may contain a combination of a quaternary ammonium compound and a weak acid salt as described above. The quaternary ammonium compound is, for example, a tetraalkylammonium hydroxide such as TMAH. As the weak acid salt, one that can be used for polishing using silica particles and can exhibit a desired buffering action in combination with a quaternary ammonium compound can be appropriately selected. The weak acid salts can be used alone or in combination of two or more. Specific examples of weak acid salts include sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium orthosilicate, potassium orthosilicate, sodium acetate, potassium acetate, sodium propionate, potassium propionate, calcium carbonate, calcium bicarbonate , Calcium acetate, calcium propionate, magnesium acetate, magnesium propionate, zinc propionate, manganese acetate, cobalt acetate and the like. Weak acid salts in which the anion component is carbonate ion or hydrogen carbonate ion are preferred, and weak acid salts in which the anion component is carbonate ion are particularly preferred. Moreover, as a cation component, alkali metal ions, such as potassium and sodium, are suitable. Particularly preferred weak acid salts include sodium carbonate, potassium carbonate, sodium bicarbonate and potassium bicarbonate. Of these, potassium carbonate (K ₂ CO ₃ ) is preferable.

When a quaternary ammonium compound and a weak acid salt are used in combination as the basic compound, the blending ratio of the quaternary ammonium compound and the weak acid salt is not particularly limited. For example, the quaternary ammonium compound: the weak acid salt Is suitably 1: 9 to 9: 1, preferably 3: 7 to 8: 2, more preferably 5: 5 to 7: 3. The quaternary ammonium compound is, for example, a tetraalkylammonium hydroxide such as TMAH. The weak acid salt is, for example, a weak acid salt whose anion component such as K ₂ CO ₃ is a carbonate ion.

In the technique disclosed herein, it is appropriate that the content of the basic compound in the polishing composition is, for example, 0.001% by weight or more, typically 0.01% by weight or more. From the viewpoint of improvement and the like, it is preferably 0.05% by weight or more, more preferably 0.08% by weight or more. The stability of the liquid A can be improved by increasing the content of the basic compound. The upper limit of the content of the basic compound is suitably 5% by weight or less, and preferably 1% by weight or less from the viewpoint of surface quality and the like. In a preferred embodiment, the content of the basic compound is, for example, 0.5% by weight or less, typically 0.2% by weight or less.

(water)
The polishing composition disclosed herein typically contains water. As water, ion exchange water (deionized water), pure water, ultrapure water, distilled water and the like can be preferably used. The water to be used preferably has, for example, a total content of transition metal ions of 100 ppb or less in order to avoid as much as possible the action of other components contained in the polishing composition. For example, the purity of water can be increased by operations such as removal of impurity ions with an ion exchange resin, removal of foreign matter with a filter, distillation, and the like. Moreover, the polishing composition disclosed here may further contain an organic solvent that can be uniformly mixed with water, if necessary. The organic solvent is a lower alcohol, a lower ketone or the like. As for the solvent contained in polishing composition, it is preferable that 90 volume% or more is water, and it is more preferable that 95 volume% or more is water. In a more preferred embodiment, typically 99 to 100% by volume of the solvent contained in the concentrate is water. In the present specification, the term “aqueous solvent” may be used as a general term including the solvent and water.

(Chelating agent)
The polishing composition disclosed herein can contain a chelating agent as an optional component. The chelating agent functions to suppress contamination of the object to be polished by metal impurities by forming complex ions with metal impurities that can be contained in the polishing composition and capturing them. Examples of chelating agents include aminocarboxylic acid chelating agents and organic phosphonic acid chelating agents. Examples of aminocarboxylic acid-based chelating agents include ethylenediaminetetraacetic acid, ethylenediaminetetraacetic acid sodium, nitrilotriacetic acid, nitrilotriacetic acid sodium, nitrilotriacetic acid ammonium, hydroxyethylethylenediaminetriacetic acid, hydroxyethylethylenediamine sodium triacetate, diethylenetriaminepentaacetic acid Diethylenetriamine sodium pentaacetate, triethylenetetramine hexaacetic acid and sodium triethylenetetramine hexaacetate. Examples of organic phosphonic acid chelating agents include 2-aminoethylphosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, aminotri (methylenephosphonic acid), ethylenediaminetetrakis (methylenephosphonic acid), diethylenetriaminepenta (methylenephosphonic). Acid), ethane-1,1-diphosphonic acid, ethane-1,1,2-triphosphonic acid, ethane-1-hydroxy-1,1-diphosphonic acid, ethane-1-hydroxy-1,1,2-triphosphonic acid Ethane-1,2-dicarboxy-1,2-diphosphonic acid, methanehydroxyphosphonic acid, 2-phosphonobutane-1,2-dicarboxylic acid, 1-phosphonobutane-2,3,4-tricarboxylic acid and α-methylphospho Nosuccinic acid is included. Of these, organic phosphonic acid chelating agents are more preferred. Of these, ethylenediaminetetrakis (methylenephosphonic acid), diethylenetriaminepenta (methylenephosphonic acid) and diethylenetriaminepentaacetic acid are preferable. Particularly preferred chelating agents include ethylenediaminetetrakis (methylenephosphonic acid) and diethylenetriaminepenta (methylenephosphonic acid). A chelating agent can be used individually by 1 type or in combination of 2 or more types.

(Other ingredients)
The polishing composition disclosed herein is a surfactant, an organic acid, an organic acid salt, an inorganic acid, an inorganic acid salt, an antiseptic, an antifungal agent, etc., as long as the effects of the present invention are not significantly hindered. You may further contain the well-known additive which can be used for polishing slurry as needed. The polishing slurry is typically a polishing slurry used in a silicon substrate polishing process.

It is preferable that the polishing composition disclosed here contains substantially no oxidizing agent. When the polishing composition contains an oxidizing agent, the polishing slurry is supplied to the object to be polished (here, the silicon substrate), whereby the surface of the object to be polished is oxidized to form an oxide film. This is because the polishing rate may decrease. Specific examples of the oxidizing agent herein include hydrogen peroxide (H ₂ O ₂ ), sodium persulfate, ammonium persulfate, sodium dichloroisocyanurate, and the like. In addition, that polishing composition does not contain an oxidizing agent substantially means not containing an oxidizing agent at least intentionally.

The pH of the polishing composition in the technique disclosed herein is preferably 8.0 or more, for example 8.5 or more, more preferably 9.0 or more, and still more preferably 9.5 or more. Further, the pH of the polishing composition in a more preferable embodiment is 10.0 or more, for example. When the pH of the polishing liquid increases, the polishing rate tends to improve. Although the upper limit of the pH of the polishing liquid is not particularly limited, it is preferably 12.0 or less, for example, 11.5 or less, and more preferably 11.0 or less, from the viewpoint of better polishing the object to be polished. . From the viewpoint of improving the surface quality, the pH is more preferably 10.8 or less. The pH of the polishing composition in a further preferred embodiment is, for example, 10.6 or less, and typically 10.5 or less. The surface quality improvement typically refers to a reduction in surface roughness. The pH can be preferably used for a polishing liquid used for polishing a silicon wafer, for example. The polishing liquid is, for example, a polishing liquid for rough polishing.

In the technique disclosed herein, the pH of the liquid composition is adjusted to 3 using a pH buffer and a standard buffer solution, and then the glass electrode is placed in the composition to be measured. It can be grasped by measuring the value after a minute or more has passed and stabilized. The liquid composition may be a polishing slurry, A liquid, B liquid, or the like. As the pH meter, for example, a glass electrode type hydrogen ion concentration indicator (model number F-23) manufactured by HORIBA, Ltd. is used. Further, the standard buffer solutions are phthalate pH buffer solution pH: 4.01 (25 ° C.), neutral phosphate pH buffer solution pH: 6.86 (25 ° C.), carbonate pH buffer solution pH: 10. 01 (25 ° C.).

<Method for producing polishing composition>
The polishing composition disclosed herein can be produced by the following method. Specifically, the above manufacturing method prepares a liquid B containing a step of preparing liquid A containing abrasive grains and a basic compound (liquid A preparation step) and a water-soluble polymer P1 having an inertia radius of 100 nm or more. And a step of mixing the solution A and the solution B (mixing step). In addition, the order of A liquid preparation process and B liquid preparation process is not specifically limited.

(A liquid preparation process)
In manufacturing the polishing composition disclosed herein, a liquid A containing abrasive grains and a basic compound is prepared. As a kind of abrasive grain contained in A liquid, the 1 type (s) or 2 or more types of the various abrasive grains illustrated as an abrasive grain which may be contained in polishing composition can be used. Examples of the various abrasive grains include silica particles, preferably colloidal silica. Similarly, the average primary particle diameter, shape, and average aspect ratio of the abrasive grains can be the average primary particle diameter, shape, and average aspect ratio that can be taken by the abrasive grains contained in the polishing composition.

The solution A is typically prepared in a form containing a higher concentration of the components than the polishing composition from the viewpoint of convenience of production, distribution, storage and the like. Therefore, the content of abrasive grains in the liquid A is also preferably higher than the content of abrasive grains in the polishing composition. Specifically, the content of the abrasive grains in the liquid A is suitably about 1% by weight or more, for example, 10% by weight or more, preferably 15% by weight or more, more preferably 20% by weight or more, Preferably it is 25 weight% or more. From the viewpoint of stability, filterability, etc., the content of the abrasive grains in the liquid A is, for example, suitably 50% by weight or less, and preferably 45% by weight or less. In a preferred embodiment, the content of abrasive grains in the liquid A is, for example, 40% by weight or less, typically 35% by weight or less.

In a preferred embodiment, from the viewpoint of stability, the entire amount of abrasive grains contained in the polishing composition is contained in the liquid A, but the technique disclosed herein is not limited thereto. As long as the effects of the present invention are not significantly impaired, part of the abrasive grains contained in the polishing composition may be contained in the liquid A. Specifically, when the total amount of abrasive grains contained in the polishing composition is 100% by weight, it is appropriate that an amount exceeding 50% by weight is contained in the liquid A, and the polishing composition It is preferable that 80% by weight or more, for example, 90% by weight or more, more preferably 95% by weight or more, typically 99% by weight to 100% by weight, of the total amount of abrasive grains contained in is contained in the liquid A.

Also about the basic compound contained in A liquid, 1 type, or 2 or more types of the various basic compounds illustrated as a basic compound which can be contained in polishing composition can be used similarly to the case of an abrasive grain. . A quaternary ammonium compound, a weak acid salt, or a combination of both is preferred. When the B liquid contains a combination of a quaternary ammonium compound and a weak acid salt as a basic compound, the blending ratio of the quaternary ammonium compound and the weak acid salt in the B liquid is not particularly limited. It is appropriate that the ratio of the quaternary ammonium compound: weak acid salt is 1: 9 to 9: 1, preferably 3: 7 to 8: 2, more preferably 5: 5 to 7: 3. The quaternary ammonium compound is, for example, tetraalkylammonium hydroxide such as TMAH. The weak acid salt is, for example, a weak acid salt in which an anion component such as K ₂ CO ₃ is a carbonate ion.

The content (concentration) of the basic compound in the liquid A is suitably, for example, 0.1% by weight or more, typically 0.5% by weight or more from the viewpoint of improving the polishing rate, preferably 1% by weight or more, more preferably 1.5% by weight or more, and further preferably 2.0% by weight or more. In a more preferred embodiment, the content of the basic compound in the liquid A is, for example, 2.5% by weight or more. For example, when the A liquid is used after being diluted at a high magnification, the concentration of the abrasive grains after dilution may be relatively low, and the processing force by the abrasive grains may tend to decrease. Even in such a case, chemical polishing after dilution can be strengthened by increasing the amount of the basic compound at the stage of the liquid A. The upper limit of the content of the basic compound in the liquid A is suitably 10% by weight or less, preferably 5% by weight or less, from the viewpoints of storage stability and surface quality. In a preferred embodiment, the content of the basic compound in the liquid A is, for example, 3% by weight or less.

Further, the content of the basic compound in the liquid A can also be specified by the relative relationship with the abrasive grains contained in the liquid A. Specifically, the content of the basic compound in the liquid A is suitably 0.1 parts by weight or more with respect to 100 parts by weight of the abrasive grains, and preferably 1 weight from the viewpoint of improving the polishing rate. Part or more, more preferably 3 parts by weight or more, still more preferably 6 parts by weight or more. From the standpoint of stability and surface quality, the content of the basic compound is suitably 50 parts by weight or less, preferably 30 parts by weight or less, more preferably 100 parts by weight of abrasive grains. 15 parts by weight or less, more preferably 12 parts by weight or less.

In the technique disclosed herein, the entire amount of the basic compound contained in the polishing composition may be contained in the A liquid, or a part thereof may be contained in the A liquid. Specifically, when the total amount of basic compounds contained in the polishing composition is 100% by weight, it is appropriate that an amount exceeding 50% by weight is contained in the liquid A. It is preferable that 80% by weight or more, for example 90% by weight or more, further 95% by weight or more, typically 99% by weight or more of the total amount of basic compounds contained in the product is contained in the liquid A. A mode in which a part of the basic compound contained in the polishing composition is included in the A liquid and the remainder is included in the B liquid described later from the viewpoint of reducing the pH difference from the B liquid when mixed with the B liquid described later. Is preferably employed. In such an embodiment, the amount of the basic compound contained in the liquid A is 99.999% by weight or less, for example, 99.99% by weight or less when the total amount of the basic compound contained in the polishing composition is 100% by weight. Typically, it can be about 99.9% by weight or less.

When the polishing composition disclosed here contains the water-soluble polymer P2 described above, it is preferable that the liquid A contains the water-soluble polymer P2 in the production of the polishing composition. This tends to improve the dispersion stability of the abrasive grains. As the water-soluble polymer P2 that can be contained in the liquid A, one or more of the various water-soluble polymers P2 exemplified as the water-soluble polymer P2 that can be contained in the polishing composition can be used. When the liquid A contains the water-soluble polymer P2, the content (concentration) of the water-soluble polymer P2 in the liquid A is 1 × 10 ⁻⁴ wt% from the viewpoint of sufficiently obtaining the effect of adding the water-soluble polymer P2. The above is appropriate, and preferably 1 × 10 ⁻³ wt% or more. In a preferred embodiment, the content of the water-soluble polymer P2 in the liquid A is, for example, 3 × 10 ⁻³ wt% or more. The upper limit of the content of the water-soluble polymer P2 in the liquid A is not particularly limited. For example, it is appropriate to set it to 1 × 10 ⁻¹ wt% or less, typically 1 × 10 ⁻² wt% or less. In addition, when the polishing composition contains the water-soluble polymer P2, the total amount of the water-soluble polymer P2 may be contained in the liquid A, a part of which is contained in the liquid A, and the remainder is contained in the liquid B. The total amount thereof may be contained in the B liquid.

The technique disclosed here can be preferably implemented in a mode in which the liquid A does not substantially contain the water-soluble polymer P1, but is included in the polishing composition as long as the effects of the present invention are not significantly impaired. A part of the water-soluble polymer P1 may be contained in the A liquid. Moreover, the said A liquid may typically contain the aqueous solvent represented by water. Liquid A is an addition of a chelating agent, a surfactant, an organic acid, an organic acid salt, an inorganic acid, an inorganic acid salt, an antiseptic, an antifungal agent and the like that can be included as an optional component in the polishing composition disclosed herein. An agent may be further contained as necessary.

The pH of the solution A disclosed herein is typically 8.0 or higher, preferably 8.5 or higher, more preferably 9.0 or higher, still more preferably 9.5 or higher, for example 10.0 or higher. And particularly preferably 10.5 or more. The polishing performance tends to be improved by increasing the pH of the liquid A. On the other hand, the pH of the liquid A is suitably 12.0 or less and 11.8 or less from the viewpoint of preventing dissolution of the abrasive grains and suppressing a decrease in mechanical polishing action by the abrasive grains. Preferably, it is 11.5 or less. The abrasive grains are, for example, silica particles.

The preparation method of the A liquid is not particularly limited. For example, each component contained in the liquid A may be mixed using a well-known mixing apparatus such as a blade-type stirrer, an ultrasonic disperser, or a homomixer. The aspect which mixes these components is not specifically limited, For example, all the components may be mixed at once and may be mixed in the order set suitably. The same mixing method can be appropriately employed for the later-described B liquid.

(B liquid preparation process)
B liquid used for manufacture of the polishing composition disclosed here contains water-soluble polymer P1 whose inertia radius is 100 nm or more. As the water-soluble polymer P1 contained in the liquid B, one or more of various water-soluble polymers exemplified as the water-soluble polymer P1 that can be contained in the polishing composition can be used.

The liquid B is also typically prepared in a form containing a higher concentration of the components than the polishing composition from the viewpoint of convenience in production, distribution, storage, etc., as with the liquid A. Therefore, the content of the water-soluble polymer P1 in the liquid B is also preferably higher than the content of the water-soluble polymer P1 in the polishing composition. Specifically, the content of the water-soluble polymer P1 in the liquid B is suitably about 0.01% by weight or more, for example 0.02% by weight or more, preferably 0.05% by weight or more. is there. In a preferred embodiment, the content of the water-soluble polymer P1 in the liquid B is, for example, 0.1% by weight or more. From the viewpoint of stability, filterability, etc., the content of the water-soluble polymer P1 in the liquid B is suitably 10% by weight or less, and preferably 3% by weight or less, for example. In a preferred embodiment, the content of the water-soluble polymer P1 in the liquid B is, for example, 1% by weight or less, typically 0.5% by weight or less.

In a preferred embodiment, from the viewpoint of stability, the entire amount of the water-soluble polymer P1 contained in the polishing composition is contained in the B solution, but the technique disclosed herein is not limited thereto. A part of the water-soluble polymer P1 contained in the polishing composition may be contained in the liquid A as long as the effects of the present invention are not significantly impaired. Specifically, when the total amount of the water-soluble polymer P1 contained in the polishing composition is 100% by weight, it is appropriate that an amount exceeding 50% by weight is contained in the B liquid. It is preferable that 80% by weight or more, for example, 90% by weight or more, further 95% by weight or more, typically 99% by weight or more of the total amount of the water-soluble polymer P1 contained in the composition for use is contained in the B liquid.

The liquid B according to a preferred embodiment includes a part of the basic compound contained in the polishing composition. Thereby, the pH difference with A liquid containing a basic compound is reduced, and A liquid and B liquid can be mixed smoothly. When the B liquid contains a basic compound, the basic compound is not particularly limited, but at least one of the basic compound contained in the liquid A to be mixed or the basic compound used as an additive during circulation use It is preferable to use the same type as. For example, potassium hydroxide or a quaternary ammonium compound can be used. The quaternary ammonium compound is, for example, a tetraalkylammonium hydroxide such as TMAH.

Further, when the polishing composition disclosed herein contains the water-soluble polymer P2, the whole or part of the water-soluble polymer P2 may be contained in the B liquid. In this case, the inertial radius of the total water-soluble polymer contained in the liquid B can be less than 100 nm, but it is contained in the liquid B even when the liquid B contains the water-soluble polymer P2 or not. It is preferable that the inertial radius of all water-soluble polymers is 100 nm or more. In a more preferred embodiment, the radius of inertia of the total water-soluble polymer contained in the liquid B is 105 nm or more, more preferably 120 nm or more, and particularly preferably 140 nm or more. The upper limit of the radius of inertia of the total water-soluble polymer contained in the B liquid is not particularly limited, and is suitably about 500 nm or less, preferably 300 nm or less, from the viewpoint of the stability and concentration efficiency of the B liquid. More preferably, it is 250 nm or less, More preferably, it is 220 nm or less, or about 150 nm or less, for example, 120 nm or less may be sufficient.

Although the technique disclosed here can be preferably implemented in a mode in which the liquid B does not substantially contain abrasive grains, one of the abrasive grains contained in the polishing composition is within a range that does not significantly impair the effects of the invention. Part may be contained in the B liquid. Moreover, the said B liquid may contain the aqueous solvent represented by water. Liquid B is an addition of a chelating agent, surfactant, organic acid, organic acid salt, inorganic acid, inorganic acid salt, preservative, antifungal agent, etc. that can be included as an optional component in the polishing composition disclosed herein. An agent may be further contained as necessary.

The pH of the B liquid disclosed here is not particularly limited. From the viewpoint of suppressing the pH change during mixing with the liquid A, the pH of the liquid B is suitably within ± 3 of the pH of the liquid A, preferably within ± 2, more preferably within ± 1. is there. In a more preferred embodiment, the pH of the solution B is, for example, within ± 0.5.

(Mixing process)
Subsequently, the A liquid and B liquid prepared as mentioned above are mixed. The mixing method is not particularly limited, and may be performed using a well-known and conventional mixing device as necessary. The timing of the mixing is not particularly limited, and the A liquid and the B liquid may be mixed at an appropriate timing before using the polishing composition, that is, before polishing using the polishing composition. For example, it is preferable not to include a process such as storage between the mixing and use of the obtained polishing composition, that is, polishing. The period from the mixing to the use of the polishing composition can be, for example, within 2 weeks, and is suitably within 3 days. In consideration of the dispersion state and the like in the polishing composition after mixing, it is preferably within 24 hours of starting polishing using the polishing composition, typically within 12 hours, immediately before the start of polishing, For example, it is more preferable to carry out the mixing step within 6 hours, typically within 3 hours. Or you may supply the manufactured polishing composition to a grinding | polishing target object, mixing A liquid and B liquid continuously.

The mixing ratio of the liquid A and the liquid B is appropriately set so that the composition of the polishing composition is in a desired range. In a preferred embodiment, in the mixing step, the liquid A: the liquid B is in a ratio of 1: 1 to 100: 1, for example 5: 1 to 70: 1, typically 15: 1 to 50: 1 on a volume basis. Mixed.

In a preferred embodiment, dilution is performed using an aqueous solvent such as water before or after the mixing of the liquid A and the liquid B or simultaneously with the mixing. By diluting at this timing, it is possible to achieve both the advantages and stability of the concentrated liquid in the state of liquid A and liquid B before use of the polishing composition. The advantages of the concentrated liquid are convenience and cost reduction. Moreover, the polishing composition obtained by diluting can exhibit an excellent edge roll-off reducing effect. In a particularly preferable embodiment, the liquid A, the liquid B and the aqueous solvent for dilution are mixed almost simultaneously or continuously added and mixed. When A liquid, B liquid, and the aqueous solvent for dilution are continuously mixed, the order of addition is not particularly limited. In order to reduce the influence of pH change due to mixing, an embodiment in which the liquid B is diluted with the aqueous solvent for dilution and then the liquid B is added to the diluted liquid A is preferably employed. As the liquid used for dilution, it is preferable to use an aqueous solvent consisting essentially of water from the viewpoints of handleability and workability. The water is typically ion exchange water. The aqueous solvent is, for example, an aqueous solvent in which 99.5 to 100% by volume is water. In addition, when the aqueous solvent is a mixed solvent, only a part of the components of the aqueous solvent may be added for dilution, and a mixture containing these components in a different ratio from the aqueous solvent. A solvent may be added for dilution.

It is appropriate that the dilution ratio with the above-mentioned aqueous solvent for dilution is larger than 2 times on a volume basis with respect to the total amount of the liquid A and the liquid B. By diluting at the above magnification, a polishing composition having a composition suitable for polishing is obtained from the concentrated liquid A and liquid B. According to the technique disclosed herein, the dilution can be performed at a magnification larger than 10 times on a volume basis, typically 15 times or more, for example, 25 times or more, based on the total amount of the liquid A and the liquid B. preferable. The upper limit of the dilution ratio is not particularly limited, but may be about 100 times or less, for example 50 times or less, typically 40 times or less on a volume basis. Therefore, the composition of the pure liquid mixture of liquid A and liquid B itself can correspond to the composition obtained by concentrating the polishing composition disclosed herein at the above magnification. Specifically, the liquid mixture of the liquid A and the liquid B may be a concentrated liquid obtained by concentrating the polishing composition having the composition described above at a magnification (concentration ratio) of more than 2 times on a volume basis. The concentration factor may be preferably greater than 10 times on a volume basis, typically 15 times or more, for example 25 times or more.

The mixing method of the liquid A, the liquid B, and the aqueous solvent for dilution used as necessary is not particularly limited. If necessary, the liquid may be mixed using a known mixing device such as a blade-type stirrer, an ultrasonic disperser, or a homomixer. The aspect which mixes the said liquid is not specifically limited, For example, A liquid, B liquid, and the aqueous solvent for dilution may be mixed at once, and you may mix in the order set suitably. In the production of the polishing composition disclosed herein, in addition to the liquid A and the liquid B, one or two or more additional agents (liquid C) containing a part of the components contained in the polishing composition , D liquid, etc.) can be mixed as optional components.

<Polishing composition set>
The polishing composition set disclosed here is a multi-drug polishing composition set used for producing the polishing composition, and includes at least the above-described A liquid and B liquid. The liquid A contains at least abrasive grains and a basic compound, and the liquid B contains at least a water-soluble polymer P1. The polishing composition set according to a preferred embodiment is a two-component type set consisting of A liquid and B liquid. In addition, since the detail of A liquid and B liquid is as above-mentioned, the overlapping description is not repeated here. Further, the polishing composition set disclosed herein includes one or two or more additional agents (C liquid, D) containing a part of the components contained in the polishing composition in addition to liquid A and liquid B. It may be referred to as a liquid or the like. The A liquid, the B liquid, and the additional agent as an optional component are typically stored in separate containers until the mixing step in the production of the polishing composition.

<Application>
The technique disclosed herein is preferably applied to polishing using a silicon substrate (particularly a silicon wafer) as an object to be polished. A typical example of the silicon wafer here is a silicon single crystal wafer, for example, a silicon single crystal wafer obtained by slicing a silicon single crystal ingot. The surface to be polished in the technique disclosed herein is typically a surface made of silicon.

The silicon substrate is subjected to general processing that can be performed on the silicon substrate in a process upstream of the rough polishing process, such as lapping and etching, before the polishing process using the polishing liquid disclosed herein. May be. In the technique disclosed herein, a finish polishing step can be performed on the silicon substrate after the polishing step (rough polishing step) using the polishing liquid. The finishing process includes one or more polishing processes, and the final polishing is performed to finish the silicon wafer into a high-quality mirror surface. Note that final polishing refers to the final polishing step in the manufacturing process of the object. That is, final polishing refers to a process in which no further polishing is performed after that process. Therefore, the polishing liquid disclosed herein, A liquid, and B liquid can be used for polishing a lapped silicon wafer. Moreover, the said polishing liquid etc. can be used for the rough polishing performed before final polishing of a silicon wafer. Rough polishing is also called preliminary polishing.

<Polishing>
Polishing of the object to be polished can be performed, for example, as follows. That is, by adopting the manufacturing method disclosed herein, specifically, the A liquid preparation step, the B liquid preparation step, and the mixing step of the A liquid and the B liquid are performed, and dilution is performed as necessary. Then, a polishing composition (polishing slurry) is prepared. Next, the polishing slurry (working slurry) is supplied to the object to be polished and polished by a conventional method. In rough polishing of a silicon wafer, typically, an object to be polished (silicon wafer) that has undergone a lapping process is set in a polishing apparatus, and the above-mentioned is performed through a polishing pad fixed to a surface plate (polishing surface plate) of the polishing apparatus. A polishing slurry is supplied to the surface of the object to be polished (surface to be polished). Typically, while continuously supplying the polishing slurry, the polishing pad is pressed against the surface of the object to be polished, and the two are relatively moved. The polishing of the object to be polished is completed through this polishing step. The movement is, for example, a rotational movement.

The polishing pad used in the above polishing process is not particularly limited. For example, a polishing pad of foamed polyurethane type, non-woven fabric type, suede type or the like can be used. Each polishing pad may include abrasive grains or may not include abrasive grains.

As the polishing apparatus, a double-side polishing apparatus that simultaneously polishes both sides of the object to be polished, or a single-side polishing apparatus that polishes only one side of the object to be polished may be used. Although not particularly limited, for example, a double-side polishing apparatus can be preferably employed in the rough polishing step. The double-side polishing apparatus is, for example, a batch type double-side polishing apparatus. The polishing apparatus may be a single wafer type polishing apparatus configured to polish one polishing object at a time, or a batch type polishing apparatus capable of simultaneously polishing a plurality of polishing objects on the same surface plate. But you can.

Although not particularly limited, the polishing composition produced using the set disclosed herein is preferably used for polishing within a relatively short period of time after the production. By this, the advantage of setting the set for manufacturing this polishing composition to a multi-drug type, that is, a configuration comprising a plurality of agents can be better utilized. The period from the production of the polishing composition to its use can be, for example, within 2 weeks, suitably within 3 days, preferably within 24 hours, preferably within 12 hours. More preferred. The period may be within 6 hours, and may be within 3 hours. Or you may supply the manufactured polishing composition to a grinding | polishing target object, manufacturing the said polishing composition using a set continuously.

The above polishing composition may be used in a so-called “flowing” form once used for polishing, or may be repeatedly used after circulation. As an example of a method of circulating and using the polishing composition, there is a method of collecting a used polishing composition discharged from the polishing apparatus in a tank and supplying the recovered polishing composition to the polishing apparatus again. . When the polishing composition is used in a circulating manner, the environmental load can be reduced by reducing the amount of the used polishing composition to be treated as a waste liquid, compared with the case of using the polishing composition by pouring. Moreover, cost can be suppressed by reducing the usage-amount of polishing composition. Since the polishing composition disclosed here is excellent in pH maintainability, it is suitable for the usage mode in which it is used in this manner. According to such a use mode, the significance of adopting the configuration of the present invention can be exhibited particularly well. When the polishing composition disclosed herein is used in a circulating manner, a new component, a component reduced by use, or a component desired to increase may be added to the polishing composition in use at any timing. Good.

<Washing>
The object to be polished that has finished the rough polishing step is typically cleaned before the finish polishing step is started. This washing can be performed using an appropriate washing solution. The cleaning liquid to be used is not particularly limited, and for example, a common SC-1 cleaning liquid, SC-2 cleaning liquid, etc. in the field of semiconductors can be used. The SC-1 cleaning liquid is a mixed liquid 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 HCl, H ₂ O ₂ and H ₂ O. The temperature of the cleaning liquid can be, for example, in the range from room temperature to about 90 ° C. Here, room temperature typically means about 15 ° C. to 25 ° C. From the viewpoint of improving the cleaning effect, a cleaning solution of about 50 ° C. to 85 ° C. can be preferably used.

The polishing of the object to be polished is completed through the rough polishing process, the cleaning process, and the final polishing process as described above. Here, the polishing object is a silicon substrate, typically a silicon single crystal wafer. Therefore, according to this specification, a method for producing a polished article including the polishing step is provided. Specifically, the manufacturing method is a method for manufacturing a silicon wafer.

As mentioned above, according to this embodiment, the method of manufacturing the composition for silicon wafer rough polishing containing an abrasive grain, a basic compound, and a water-soluble polymer is provided. The production method includes: a step of preparing a liquid A containing the abrasive grains and the basic compound; and a step of preparing a liquid B containing a water-soluble polymer P1 having an inertial radius of 100 nm or more as the water-soluble polymer. And a step of mixing the liquid A and the liquid B. The polishing composition obtained by such a method can improve edge roll-off in polishing a silicon substrate by including the water-soluble polymer P1 having a predetermined or larger inertia radius. Moreover, the polishing composition before completion, in other words, before use, is a multi-drug type having a liquid A and a liquid B. Concentration such as convenience and cost reduction is achieved by increasing the concentration of each liquid (concentrated liquid). You can enjoy the benefits of liquid. In addition, since the abrasive grains and the water-soluble polymer P1 are separately stored in the liquid A and the liquid B, an event in which the dispersion of the water-soluble polymer P1 is hindered by the presence of the abrasive grains can be avoided. As a result, the polishing composition before completion shows excellent stability in the state of liquid A and liquid B. Therefore, according to the present invention, it is possible to produce a silicon wafer rough polishing composition that is excellent in stability and can improve edge roll-off while enjoying the advantages of the concentrate.

In a preferred aspect of the technology disclosed herein, the method includes a step of diluting at least one of the liquid A, the liquid B, and a mixed liquid of the liquid A and the liquid B. Moreover, the dilution rate in the dilution step is a rate larger than 10 times on a volume basis with respect to the total amount of the liquid A and the liquid B. By adopting such a method, the polishing composition before completion can achieve both the advantages and stability of the concentrated liquid, and the polishing composition in which the liquid A and the liquid B are mixed at the time of use. As a result, an edge roll-off reduction effect can be exhibited. The advantages of the concentrated liquid are convenience and cost reduction. The dilution step may be performed before the step of mixing the liquid A and the liquid B, simultaneously with the mixing step, or after the mixing step. In addition, the technique disclosed here includes a method for manufacturing a composition for rough polishing of a silicon wafer, a composition set for rough polishing of a silicon wafer, a method for polishing a silicon wafer, and the like.

In a preferred embodiment of the technology disclosed herein, the inertial radius of the water-soluble polymer contained in the liquid B is 100 nm or more. After preparing this B liquid, if necessary, it is stored and mixed with the A liquid at the time of use of the polishing composition, whereby the effects of the technique disclosed herein are preferably exhibited.

In a preferred embodiment of the technology disclosed herein, the content of the abrasive grains in the liquid A is 10% by weight or more. In the embodiment using the liquid A containing abrasive grains at a predetermined concentration or more, the effect of the technique disclosed herein is preferably exhibited.

In a preferred embodiment of the technology disclosed herein, the content of the water-soluble polymer P1 in the liquid B is 0.01% by weight or more. In the embodiment using the liquid B containing the water-soluble polymer at a predetermined concentration or more, the effect by the technique disclosed herein is preferably exhibited.

Also, according to this embodiment, a polishing composition set for producing a silicon wafer rough polishing composition containing abrasive grains, a basic compound and a water-soluble polymer is provided. Such a polishing composition set includes a liquid A containing the abrasive grains and the basic compound, and a liquid B containing a water-soluble polymer P1 having an inertia radius of 100 nm or more as the water-soluble polymer. According to such a configuration, the liquid A and the liquid B each have excellent stability while enjoying the advantages of the concentrated liquid when used as a concentrated liquid before use, for example, during storage. Then, liquid A and liquid B are mixed at an appropriate timing to obtain a polishing composition (polishing slurry), and by using this, the edge roll-off of the silicon substrate can be improved. The advantages of the concentrated liquid are convenience and cost reduction.

Further, according to the present embodiment, a method for polishing a silicon wafer including a rough polishing step and a final polishing step is provided. This polishing method includes a step of preparing a rough polishing composition used in the rough polishing step before the rough polishing step. The step of preparing the rough polishing composition includes: a step of preparing a solution A containing abrasive grains and a basic compound; and a step of preparing a solution B containing a water-soluble polymer P1 having an inertia radius of 100 nm or more. And a step of mixing the liquid A and the liquid B. According to this method, the polishing composition before use can be made into a concentrated solution having excellent stability in a state where the polishing composition is separated into the liquid A and the liquid B. Moreover, edge roll-off of the silicon substrate can be improved by performing rough polishing using the polishing composition.

In a typical embodiment of the technology disclosed herein, the rough polishing composition is used for polishing a lapped silicon wafer. More specifically, the rough polishing composition is used for rough polishing (preliminary polishing) performed before final polishing of a silicon wafer.

Hereinafter, some examples relating to the present invention will be described. However, the present invention is not intended to be limited to the examples shown in the examples. In the following description, “%” is based on weight unless otherwise specified.

<Example 1>
By mixing colloidal silica (average primary particle diameter 55 nm) as abrasive grains, TMAH, K ₂ CO ₃ , water-soluble polymer P2 (PVP Mw 4.5 × 10 ⁴ ), and ion-exchanged water, A liquid A containing abrasive grains, TMAH, K ₂ CO ₃ and water-soluble polymer P2 at concentrations of 32.97%, 1.62%, 1.05% and 0.0069%, respectively, was prepared. The pH of solution A was 11.2.
Further, by mixing water-soluble polymer P1 (HEC), TMAH, and ion-exchanged water, liquid B containing water-soluble polymer P1 and TMAH at concentrations of 0.25% and 0.018%, respectively. Prepared. The pH of solution B was 11.0.
The obtained liquid A and liquid B were diluted and mixed with ion-exchanged water to obtain a polishing liquid (working slurry) according to this example. The mixing was performed such that A liquid: B liquid: ion-exchanged water had a volume ratio of 3.3: 0.1: 96.6.

<Examples 2 to 3, Comparative Example 1>
A liquid A and a liquid B were prepared in the same manner as in Example 1 except that HEC having a different inertial radius was used as the water-soluble polymer P1, and a polishing liquid (working slurry) according to this example was obtained.

<Example 4>
A liquid A and a B liquid were prepared in the same manner as in Example 3 except that the water-soluble polymer P2 was not used, and a polishing liquid (working slurry) according to this example was obtained.

<Example 5>
By mixing colloidal silica (average primary particle diameter 55 nm) as abrasive grains, TMAH, K ₂ CO ₃ , and ion-exchanged water, 32.97% of abrasive grains, TMAH and K ₂ CO ₃ are respectively obtained. Solution A containing 1.62% and 1.05% concentrations was prepared. The pH of solution A was 11.2.
Further, by mixing water-soluble polymer P1 (HEC), water-soluble polymer P2 (PVP Mw4.5 × 10 ⁴ ), TMAH and ion-exchanged water, water-soluble polymer P1, water-soluble polymer P1 Liquid B containing molecules P2 and TMAH at concentrations of 0.25%, 0.28%, and 0.018%, respectively, was prepared. The pH of solution B was 11.0.
A polishing liquid (working slurry) according to this example was obtained in the same manner as in Example 1 except that the obtained liquid A and liquid B were used.

<Example 6>
In Example 3, the polishing liquid (working slurry) according to this example was obtained in the same manner as in Example 3 except that 0.018% of TMAH contained in the B liquid was changed to 0.011% of potassium hydroxide (KOH). .

<Comparative Examples 2 to 5>
Colloidal silica (average primary particle diameter 55 nm) as abrasive grains, water-soluble polymer P1 (HEC), TMAH, K ₂ CO ₃ , water-soluble polymer P2 (PVP Mw 4.5 × 10 ⁴ ), Concentrated liquids (one agent type) of polishing compositions according to Comparative Examples 2 to 5 were prepared by mixing with ion-exchanged water. The concentrations of the abrasive grains, water-soluble polymer P1, TMAH, K ₂ CO ₃ and water-soluble polymer P2 in the concentrated liquid of each example were 32.97%, 0.0061%, 1.62%, and 1.05, respectively. % And 0.0069%.
The obtained concentrated liquid was diluted with ion exchange water to obtain a polishing liquid (working slurry) according to this example. The dilution was performed such that the ratio of concentrated solution: ion exchanged water was 3.3: 96.7 on a volume basis.

<Comparative Example 6>
A polishing liquid (working slurry) according to this example was obtained in the same manner as in Comparative Example 5 except that the water-soluble polymer P2 was not used.

[Measurement method of inertia radius]
In order to measure the inertial radius of the water-soluble polymer, first, an aqueous solution was prepared so that the concentration of the water-soluble polymer was in the range of 0.1 to 1 mg / mL, and a light scattering photometer “DLS- 8000 "(manufactured by Otsuka Electronics Co., Ltd.), measurement was performed every 10 degrees within a measurement angle range of 20 to 150 degrees, and the inertia radius [nm] was calculated by 1 concentration method plot analysis. The measurement was performed on the water-soluble polymer P1 and the water-soluble polymer contained in the B liquid. When a plurality of types of water-soluble polymers were contained in the liquid B, the measurement was carried out by adjusting the water-soluble polymer amount so that the concentration ratio would be the same. The measurement results are shown in Table 1.

[Stability]
100 g of each of solution A and solution B prepared in Examples 1 to 6 and Comparative Example 1 was placed in a glass tube having a diameter of 2.5 cm and a height of 25 cm, and was stored separately at 25 ° C. Further, the concentrated solutions according to Comparative Examples 2 to 6 were stored under the same conditions as described above. The states of Liquid A, Liquid B, and concentrated liquid after the lapse of 24 hours from the start of storage were evaluated visually according to the following two criteria. That is, when separation or aggregation of the components in the liquid was not observed, it was evaluated as “A”, and when separation or aggregation was observed, it was evaluated as “B”. The results are shown in Table 1.

[Silicon wafer polishing]
Using the polishing liquid (working slurry) according to each example, rough polishing was performed under the following conditions.
(Polishing conditions)
Polishing device: Single-side polishing device manufactured by Nippon Engis Co., Ltd. Model “EJ-380IN”
Polishing pad: Product name “MH S-15A”, manufactured by Nitta Haas
Polishing pressure: 26.6 kPa
Slurry flow rate: 100 mL / min Plate rotation speed: 50 rpm
Head rotation speed: 50 rpm
Polishing amount: 8μm
Work species: Bare Si ^P - <100>
Work size: □ 60mm × 60mm

[Edge roll-off]
Using a non-contact surface shape measuring instrument (trade name “NewView 5032”, manufactured by Zygo, available from Canon Inc.), the reference height is calculated from the center (20 mm square from the center) of the polished surface after polishing. The change in height at a position of about 2.5 mm from the outer peripheral edge of the polished article was measured, and this was used as the edge roll-off amount. The measured edge roll-off amount was evaluated according to the following four criteria.
A: Edge roll-off amount less than 250 nm B: Edge roll-off amount 250 nm or more and less than 280 nm C: Edge roll-off amount 280 nm or more and less than 300 nm D: Edge roll-off amount 300 nm or more A to C are practically acceptable levels, D is not acceptable Considered a pass. The results are shown in Table 1.

[Surface roughness Ra]
For the silicon wafer after rough polishing according to each example (test piece after rough polishing and subsequent cleaning), a non-contact surface shape measuring machine (trade name “NewView 5032”, manufactured by Zygo, available from Canon Inc.) The surface roughness Ra (arithmetic average surface roughness) was measured. The obtained measured value was converted into a relative value with the surface roughness Ra of Example 4 as 100% and evaluated in the following two steps. The results are shown in Table 1.
A: Less than 100% B: 100% or more

As shown in Table 1, in Examples 1 to 6 in which A liquid containing abrasive grains and a basic compound and B liquid containing water-soluble polymer P1 were prepared separately, both A liquid and B liquid were stable. It was excellent. On the other hand, in Comparative Examples 3 to 6 using a one-pack type concentrate, good stability could not be obtained. Further, in Examples 1 to 6 using the water-soluble polymer P1 having an inertia radius of 100 nm or more, the edge roll-off is improved as compared with Comparative Examples 1 and 2 using the water-soluble polymer having an inertia radius of less than 100 nm. It was done. Further, in Examples 1 to 3, 5 and 6 in which the water-soluble polymer P2 was used in combination, the surface roughness Ra tended to be improved as compared with Example 4 in which the water-soluble polymer P2 was not used. It was.

Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

Claims

A method for producing a silicon wafer rough polishing composition comprising abrasive grains, a basic compound and a water-soluble polymer,
Preparing a liquid A containing the abrasive grains and the basic compound;
Preparing a solution B containing the water-soluble polymer P1 having an inertial radius of 100 nm or more as the water-soluble polymer;
Mixing the liquid A and the liquid B;
The manufacturing method of the composition for silicon wafer rough polishing including this.
Diluting at least one of the liquid A, the liquid B, and a mixed liquid of the liquid A and the liquid B,
The production method according to claim 1, wherein a dilution ratio in the dilution step is a magnification larger than 10 times on a volume basis with respect to a total amount of the liquid A and the liquid B.
The manufacturing method according to claim 1 or 2, wherein the inertial radius of the water-soluble polymer contained in the liquid B is 100 nm or more.
The production method according to any one of claims 1 to 3, wherein the content of the abrasive grains in the liquid A is 10% by weight or more.
The production method according to any one of claims 1 to 4, wherein the content of the water-soluble polymer P1 in the liquid B is 0.01 wt% or more.
A polishing composition set for producing a silicon wafer rough polishing composition comprising abrasive grains, a basic compound and a water-soluble polymer,
A silicon wafer rough polishing composition set comprising: A liquid containing the abrasive grains and the basic compound; and B liquid containing water-soluble polymer P1 having an inertial radius of 100 nm or more as the water-soluble polymer.
A silicon wafer polishing method including a rough polishing step and a final polishing step,
Before the rough polishing step, including a step of preparing a composition for rough polishing used in the rough polishing step,
The step of preparing the rough polishing composition comprises:
Preparing a liquid A containing abrasive grains and a basic compound;
Preparing a solution B containing a water-soluble polymer P1 having an inertia radius of 100 nm or more;
Mixing the liquid A and the liquid B;
A method for polishing a silicon wafer, comprising: