JPWO2018025656A1 - Method for producing composition for rough polishing silicon wafer, composition set for rough polishing silicon wafer, and method for polishing silicon wafer - Google Patents

Abstract

Provided is a method for producing a silicon wafer rough polishing composition that can achieve both the advantages of a concentrate and excellent stability and can improve edge roll-off. The method for producing a composition for roughly polishing a silicon wafer provided by the present invention is a method for producing a composition for roughly polishing a silicon wafer containing an abrasive, a basic compound and a water-soluble polymer. This manufacturing method comprises: preparing A solution containing the abrasive grains and the basic compound; and preparing B solution 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 solution A and the solution B.

Description

The present invention relates to a method for producing a polishing composition, a polishing composition set, and a polishing method. More particularly, the present invention relates to a method for producing a polishing composition used for rough polishing of a silicon wafer, a set of the polishing composition, 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 content of the application is incorporated herein by reference.

  In general, the surface of a silicon substrate used for manufacturing a semiconductor product or the like is finished into a high quality mirror surface through a lapping process and a polishing process. The polishing step typically includes a pre-polishing step (rough polishing step) and a finish polishing step (finish polishing step). The polishing step is carried out using a polishing composition (polishing slurry). As a prior art document disclosing the polishing composition used for polishing a silicon substrate, patent document 1 is mentioned. 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 and cost reduction in production, distribution, storage, and the like. That is, the polishing composition may be in the form of a concentrate of the polishing liquid. The prepared concentrate is diluted with water or the like and then used for polishing. Patent documents 2 and 3 are mentioned as a document which discloses this kind of prior art. Patent Document 4 is a document disclosing the radius of inertia of hydroxycellulose used in a polishing composition.

Japanese Patent Application Publication 2014-216464 Japanese Patent Application Publication 2012-89862 Japanese Patent Application Publication 2015-155523 Japanese Patent Application Publication 2015-124231

  As a result of examining the performance improvement of the composition for rough polishing of a silicon wafer, the present inventors have examined after polishing by using a water-soluble polymer having a predetermined radius of inertia or more as shown in the examples described later. It has been found that the phenomenon that the thickness of the outer peripheral portion (near the edge) is undesirably decreased, that is, the edge roll off can be improved. However, the stability of the water-soluble polymer having a large radius of inertia tends to decrease when the polishing composition is stored as a concentrate. Specifically, since the concentrate contains components such as abrasive grains and water-soluble polymers at a higher concentration than in use, there is a risk that good stability may not be obtained, such as separation and aggregation of the components. is there.

  The present invention has been made in view of the above-described circumstances, and it is possible to achieve both the advantages of the concentrate and the excellent stability, and to improve the edge roll-off. The purpose is to provide a method of manufacturing an object. Another related objective is to provide a silicon wafer rough polishing composition set and a method of polishing a silicon wafer.

  According to the present invention, there is provided a method for producing a silicon wafer rough polishing composition comprising abrasive grains, a basic compound and a water-soluble polymer. This manufacturing method comprises: preparing A solution containing the abrasive grains and the basic compound; and preparing B solution 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 solution A and the solution B. The polishing composition obtained by such a method can improve the edge roll-off in the polishing of the silicon substrate by including the water-soluble polymer P1 having a predetermined radius of inertia or more. Moreover, the polishing composition before completion, in other words, before use is a multi-component type having solution A and solution B, and concentration, such as convenience and cost reduction, is achieved by increasing the concentration of each solution (condensing liquefaction) You can enjoy the benefits of liquid. Further, since the abrasive grains and the water-soluble polymer P1 are separately contained in the solution A and the solution B, it is possible to avoid an event that the dispersion of the water-soluble polymer P1 is inhibited by the presence of the abrasive grains. As a result, the polishing composition before completion exhibits excellent stability in the state of solution A and solution B. Therefore, according to the present invention, it is possible to manufacture a silicon wafer rough polishing composition which is excellent in stability and can improve edge roll-off while enjoying the advantage of a concentrate.

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

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

  Hereinafter, preferred embodiments of the present invention will be described. The matters other than the matters specifically mentioned in the present specification and necessary for the implementation of the present invention can be understood as the design matters of those skilled in the art based on the prior art in the relevant field. The present invention can be implemented based on the contents disclosed in the present 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.

<Composition for polishing>
(Abrasive)
The polishing composition disclosed herein comprises abrasive grains. The material and properties of the abrasive are not particularly limited, and can be appropriately selected according to the purpose of use, mode of use, and the like. Examples of the abrasive 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; Nitride particles such as silicon nitride particles and boron nitride particles; carbide particles such as silicon carbide particles and boron carbide particles; diamond particles; and carbonates such as calcium carbonate and barium carbonate. Specific examples of the organic particles include poly (methyl methacrylate) (PMMA) particles, poly (meth) acrylic acid particles, and polyacrylonitrile particles. Such abrasive grains may be used alone or in combination of two or more. In addition, (meth) acrylic acid is a meaning which points out acrylic acid and methacrylic acid generically.

  As the abrasive, inorganic particles are preferable, and particles made of metal or metalloid oxide are particularly preferable. Particularly preferred abrasives in the art disclosed herein include silica particles. The technique disclosed herein can be preferably practiced, for example, in a mode in which the abrasive grains substantially consist 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. 100% by weight of the particles constituting the abrasive may be silica particles.

  Specific examples of the silica particles include colloidal silica, fumed silica, precipitated silica and the like. The silica particles can be used alone or in combination of two or more. Colloidal silica is particularly preferable because it is resistant to scratching on the surface of the object to be polished and can exhibit good polishing performance. The above-mentioned polishing performance is the performance etc. which reduce surface roughness. As the colloidal silica, for example, colloidal silica prepared using water glass (Na silicate) as a raw material by an ion exchange method, or alkoxide method colloidal silica can be preferably employed. Alkoxide method colloidal silica refers to colloidal silica produced by hydrolysis condensation reaction of alkoxysilane. Colloidal silica can be used singly or in combination of two or more.

  The true specific gravity of the silica constituting the silica particles is preferably 1.5 or more, more preferably 1.6 or more, and still more preferably 1.7 or more. The polishing rate tends to be high due to the increase of the true specific gravity of silica. From this viewpoint, silica particles having a true specific gravity of 2.0 or more, for example, 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 value measured by a liquid displacement method using ethanol as a displacement liquid can be adopted.

The average primary particle size of the abrasive grains disclosed herein is not particularly limited. From the viewpoint of polishing rate etc., the average primary particle diameter is suitably 5 nm or more, preferably 10 nm or more, more preferably 30 nm or more, still more preferably 40 nm or more, particularly preferably 45 nm or more. In one particularly preferred embodiment, the average primary particle size is, for example, 50 nm or more. The abrasive is typically a silica particle. Further, from the viewpoint of scratch prevention etc., the average primary particle diameter of the abrasive grains 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 may be
In the present specification, the average primary particle diameter means the BET diameter [nm] = 6000 / (true density [g / cm ³ ] × BET value [m ² ] from the specific surface area (BET value) measured by the BET method. Particle diameter calculated by the equation of For example, in the case of silica particles, the BET diameter can be calculated by BET diameter [nm] = 2727 / BET value [m ² / g]. The measurement of the specific surface area can be performed, for example, using a surface area measurement device manufactured by Micromeritex, trade name "Flow Sorb II 2300".

  The shape (outer shape) of the abrasive may be spherical or non-spherical. Specific examples of non-spherical particles include peanut shape, bowl shape, confetti shape, rugby ball shape and the like. The peanut shape is, i.e., the shape of a peanut shell. For example, abrasive grains in which many of the particles have a peanut shape may be preferably employed.

  Although not particularly limited, the average value (average aspect ratio) of the major axis / minor axis ratio of the abrasive grains is in principle 1.0 or more, preferably 1.05 or more, more preferably 1.1 or more It is. Higher polishing rates 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, and 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, electron microscope observation. As a specific procedure for grasping the average aspect ratio, for example, for a predetermined number of silica particles which can recognize the shape of independent particles using a scanning electron microscope (SEM), the smallest circumscribed particle image is used. Draw a rectangle. The predetermined number is, for example, 200. Then, for the rectangle drawn for each particle image, the ratio of the major axis to the minor axis ratio (aspect ratio) is a value obtained by dividing the length of the long side (value of the major axis) by the length of the short side (value of the minor axis) Calculated as). The average aspect ratio can be determined 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, and is preferably 0.05% by weight or more, more preferably 0.1% by weight or more, and still more preferably 0.3% by weight or more. It is. In a further preferred aspect, 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. From the viewpoint of removability from the object to be polished, the content is suitably 10% by weight or less, preferably 7% by weight or less, more preferably 5% by weight or less, still more preferably 3% by weight or less It is. In a further 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 comprises a water-soluble polymer P1 having a radius of inertia of 100 nm or more. The edge roll off is improved by using the water-soluble polymer P1 having the above-mentioned radius of inertia. The reason is not particularly limited, but the water-soluble polymer P1 having a predetermined or more inertial radius contained in the polishing composition (polishing slurry) is strongly adsorbed to the end of the substrate to be polished. By avoiding excessive polishing, it is presumed that the increase in edge roll-off (end sag) is suppressed. The radius of inertia of the water-soluble polymer P1 is the size of one molecule of the water-soluble polymer P1 in an aqueous solution, and can be determined mainly by the hydrophilicity, molecular weight and the like of the polymer P1. From the viewpoint of improving the 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 in view of the stability and concentration efficiency of the solution B used as the water-soluble polymer P1-containing liquid in the production of a polishing composition, Is preferably 300 nm or less, more preferably 250 nm or less, and still more preferably 220 nm or less. The above-mentioned radius of inertia of the water-soluble polymer P1 may be, for example, 150 nm or less and 120 nm or less. The radius of inertia of the water-soluble polymer in the present specification is measured by the method described in the examples below.

  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 types known in the field of polishing compositions. The water-soluble polymer P1 can be used singly 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 them, from the viewpoint of improving flatness, a cellulose derivative and a starch derivative are preferable, and a cellulose derivative is more preferable.

  Cellulose derivatives are polymers comprising 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. Among these, HEC is preferred.

  Starch derivatives are polymers comprising α-glucose units as the main repeat unit. Specific examples of starch derivatives include pregelatinized starch, pullulan, carboxymethyl starch, cyclodextrin and the like. Among them, pullulan is preferred.

Examples of the polymer containing an oxyalkylene unit include polyethylene oxide (PEO), a block copolymer of ethylene oxide (EO) and propylene oxide (PO) or butylene oxide (BO), and random copolymer of EO and PO or BO. A combination etc. are illustrated. Among them, block copolymers of EO and PO or random copolymers of EO and PO are preferable. The block copolymer of EO and PO can be a diblock, triblock, etc. comprising PEO blocks and polypropylene oxide (PPO) blocks. Examples of the triblocks include PEO-PPO-PEO triblocks and PPO-PEO-PPO triblocks. Among them, PEO-PPO-PEO triblocks are more preferable.
In the block copolymer or random copolymer of EO and PO, the molar ratio [EO / PO] of EO to PO constituting the copolymer is from the viewpoint of solubility in water, washability, etc. More than 1 is preferable, 2 or more is more preferable, and 3 or more is more preferable. In a further preferred embodiment, the molar ratio [EO / PO] is, for example, 5 or more.

  As the polymer containing a nitrogen atom, any of a polymer containing a nitrogen atom in the main chain and a polymer having a nitrogen atom in a side chain functional group (a pendant group) can be used. The surface roughness of the substrate can be improved by using a polymer containing nitrogen atoms. Examples of polymers containing nitrogen atoms in the main chain include homopolymers and copolymers of N-acyl alkyleneimine type monomers. Specific examples of the N-acyl alkyleneimine type monomer include N-acetyl ethyleneimine, N-propionyl ethyleneimine and the like. As a polymer which has a nitrogen atom in a pendant group, the polymer etc. which contain the monomer unit of a N-vinyl type, for example are mentioned. For example, homopolymers and copolymers of N-vinyl pyrrolidone can be employed. In the technology disclosed herein, at least one of N-vinylpyrrolidone homopolymers and copolymers (hereinafter also referred to as “PVP”) obtained by polymerizing N-vinylpyrrolidone in a proportion of 50 mol% or more is referred to as “PVP”. It is preferably used.

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

In the technology disclosed herein, the molecular weight of the water-soluble polymer P1 is not particularly limited. From the viewpoint of concentration efficiency etc., the weight average molecular weight (Mw) of the water-soluble polymer P1 can be about 300 × 10 ⁴ or less, and 150 × 10 ⁴ or less is suitable. The Mw may be, for example, 130 × 10 ⁴ or less and 110 × 10 ⁴ or less. Further, from the viewpoint of improving the protective property of the substrate surface and 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 preferable aspect, 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 above Mw can be particularly preferably employed for cellulose derivatives. As said cellulose derivative, HEC is mentioned, for example.

  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 and the like, for example, those having a molecular weight distribution [Mw / Mn] of 10.0 or less are preferable, and those having 7.0 or less are more preferable.

  In addition, as Mw and Mn of water-soluble polymer P1, the value (water system, polyethylene oxide conversion) based on the gel permeation chromatography (GPC) of a water system is employable. 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 polishing performance, surface quality improvement, etc. And preferably 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. 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 from the viewpoint of stability at the concentrate stage, polishing rate, washability, etc. It is at most 0.02 wt%, particularly preferably at most 0.01 wt%. In one particularly preferred embodiment, the content of the water-soluble polymer P1 is, for example, 0.005% by weight or less, and typically 0.001% by weight or less. The concentrate is typically solution B.

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

(Water-soluble polymer P2)
In a preferred embodiment of the art disclosed herein, the polishing composition further includes a water-soluble polymer P2 having a radius of inertia of less than 100 nm, in addition to the water-soluble polymer P1 having a radius of inertia of 100 nm or more. Unlike the water-soluble polymer P1, the water-soluble polymer P2 is also a substrate surface protecting agent because it is a component that plays a role of protecting the substrate surface such as etching suppression and contributes to the reduction of the surface roughness. The inertial radius 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 radius of inertia of the water-soluble polymer P2 is, for example, less than 30 nm, typically less than 5 nm. The lower limit of the radius of inertia 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 types 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, polyvinyl alcohol and the like. From the viewpoint of reducing surface roughness, the water-soluble polymer P2 is preferably a polymer other than a cellulose derivative and / or a starch derivative, and more preferably a polymer containing a nitrogen atom. The polymer other than the above-mentioned cellulose derivative and / or starch derivative is typically a polymer other than a cellulose derivative. As a specific example of a cellulose derivative, a starch derivative, a polymer containing an oxyalkylene unit, a polymer containing a nitrogen atom, and a 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 a side chain functional group (a pendant group) are preferable, and a polymer containing a monomer unit of N-vinyl type is more preferable. Among them, homopolymers and copolymers (typically PVP) of N-vinylpyrrolidone and the like are particularly preferable.

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 150 × 10 ⁴ or less, for example, 50 × 10 ⁴ or less is appropriate. From the viewpoint of stability etc., the Mw may be 30 × 10 ⁴ or less, for example 5 × 10 ⁴ or less. In addition, from the viewpoint of improving the protection of the substrate surface, the Mw is suitably 1 × 10 ⁴ or more, more preferably 2 × 10 ⁴ or more, and still more preferably 3 × 10 ⁴ or more. The above Mw can be particularly preferably employed for homopolymers and copolymers (typically PVP) of N-vinyl pyrrolidone.

  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 and the like, for example, those having a molecular weight distribution [Mw / Mn] of 10.0 or less are preferable, those having 7.0 or less are more preferable, and those having 5.0 or less are more preferable. Particularly preferred is 4.0 or less, and most preferred is 3.0 or less.

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

  In the polishing composition according to one aspect, 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, which is preferable from the viewpoint of stability Is less than 80% by weight, more preferably less than 70% by weight. In a more preferable aspect, the content of the water-soluble polymer P2 is, for example, less than 60% by weight. Further, from the viewpoint of surface roughness reduction etc., the content of the water-soluble polymer P2 can be about 10 wt% or more when the content of the water-soluble polymer P1 is 100 wt%, 30 wt% % Or more is suitable, preferably 50% by weight or more. In the technology disclosed herein, the content of the water-soluble polymer other than the water-soluble polymer P1 is the content of the water-soluble polymer P1 regardless of whether or not the polishing composition contains the water-soluble polymer P2. When the amount is 100% by weight, it may be about less than 200% by weight, for example, less than 150% by weight, or even less than 100% by weight. From the viewpoint of stability, when the content of the water-soluble polymer P1 is 100% by weight, the content of the water-soluble polymer other than the water-soluble polymer P1 is preferably less than 80% by weight, more preferably 70% % May be less than 50% by weight, such as less than 30% by weight, and may be less than 10% by weight, such as 1% by weight or less, specifically 0 to 1% by weight. In a more preferable 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, a basic compound refers to a compound having a function of dissolving in water to raise the pH of an aqueous solution. As the basic compound, organic or inorganic basic compounds containing nitrogen, hydroxides of alkali metals, hydroxides of alkaline earth metals, various carbonates, hydrogencarbonates and the like can be used. Examples of the nitrogen-containing basic compound 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 alone or in combination of two or more.

  Potassium hydroxide, sodium hydroxide etc. are mentioned as a specific example of the hydroxide of an alkali metal. 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 the amine include methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, ethylenediamine, monoethanolamine, N- (β-aminoethyl) ethanolamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, anhydrous piperazine And piperazine hexahydrate, 1- (2-aminoethyl) piperazine, N-methyl piperazine, guanidine, azoles such as imidazole and triazole, and the like. Specific examples of the quaternary phosphonium compound include quaternary phosphonium hydroxide such as tetramethyl phosphonium hydroxide and tetraethyl phosphonium hydroxide.

As a quaternary ammonium compound, quaternary ammonium salts, such as a tetraalkyl ammonium salt and a hydroxyalkyl trialkyl ammonium salt, can be used preferably. The quaternary ammonium salt is typically a strong base. The anion component in such a quaternary ammonium salt may 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 hydroxides include hydroxides such as tetramethyl ammonium hydroxide, tetraethyl ammonium hydroxide, tetrapropyl ammonium hydroxide, tetrabutyl ammonium hydroxide, tetrapentyl ammonium hydroxide and tetrahexyl ammonium hydroxide. Tetraalkyl ammonium; Hydroxyalkyl trialkyl ammonium hydroxide such as 2-hydroxyethyl trimethyl ammonium hydroxide (also referred to as choline); and the like. Among these, tetraalkylammonium hydroxide is preferable, and tetramethylammonium hydroxide (TMAH) is particularly preferable.

The polishing composition disclosed herein can include the combination of a quaternary ammonium compound and a weak acid salt as described above. The quaternary ammonium compound is, for example, tetraalkylammonium hydroxide such as TMAH. As the weak acid salt, one that can be used for polishing using silica particles and that can exert a desired buffering action in combination with a quaternary ammonium compound can be appropriately selected. A weak acid salt can be used individually by 1 type or in combination of 2 or more types. Specific examples of weak acid salts include sodium carbonate, potassium carbonate, sodium hydrogencarbonate, potassium hydrogencarbonate, sodium orthosilicate, potassium orthosilicate, sodium acetate, potassium acetate, sodium propionate, sodium propionate, potassium propionate, calcium carbonate, calcium hydrogencarbonate And calcium acetate, calcium propionate, magnesium acetate, magnesium propionate, zinc propionate, manganese acetate, cobalt acetate and the like. A weak acid salt in which the anion component is a carbonate ion or a hydrogen carbonate ion is preferred, and a weak acid salt in which the anion component is a carbonate ion is 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 hydrogen carbonate and potassium hydrogen carbonate. Among them, potassium carbonate (K ₂ CO ₃ ) is preferable.

When a quaternary ammonium compound and a weak acid salt are used in combination as a basic compound, the compounding ratio of the quaternary ammonium compound and the weak acid salt is not particularly limited. For example, quaternary ammonium compound: 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, 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.

  In the art disclosed herein, the content of the basic compound in the polishing composition is, for example, suitably 0.001% by weight or more, typically 0.01% by weight or more, and the polishing rate is suitable. From the viewpoint of improvement etc., it is preferably 0.05% by weight or more, more preferably 0.08% by weight or more. The stability of the solution 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, and typically 0.2% by weight or less.

(water)
The polishing composition disclosed herein typically comprises water. As water, ion exchange water (deionized water), pure water, ultrapure water, distilled water or 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 the inhibition of the functions 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 ion exchange resin, removal of foreign matter by filter, and distillation. In addition, the polishing composition disclosed herein may further contain an organic solvent that can be uniformly mixed with water, if necessary. The organic solvents are lower alcohols, lower ketones and the like. It is preferable that 90 volume% or more of the solvent contained in polishing composition 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 generic term including the above-mentioned 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 the contamination of the object to be polished by the metal impurities by forming complex ions with the metal impurities which may be contained in the polishing composition and capturing the complex ions. Examples of chelating agents include aminocarboxylic acid-based chelating agents and organic phosphonic acid-based chelating agents. Examples of aminocarboxylic acid chelating agents include ethylenediaminetetraacetic acid, sodium ethylenediaminetetraacetate, nitrilotriacetic acid, sodium nitrilotriacetate, ammonium nitrilotriacetate, ammonium hydroxyethylethylenediaminetriacetic acid, sodium hydroxyethylethylenediaminetriacetate, diethylenetriaminepentaacetic acid Sodium diethylene triamine pentaacetate, triethylene tetramine hexaacetic acid and sodium triethylene tetramine hexaacetate. Examples of organic phosphonic acid type chelating agents include 2-aminoethyl phosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, aminotri (methylene phosphonic acid), ethylene diamine tetrakis (methylene phosphonic acid), diethylene triamine penta (methylene phosphonic acid) 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-methylphosphorus Includes nosuccinic acid. Among these, organic phosphonic acid type chelating agents are more preferable. Among them, preferred are ethylenediaminetetrakis (methylene phosphonic acid), diethylene triamine penta (methylene phosphonic acid) and diethylene triamine pentaacetic acid. Particularly preferred chelating agents include ethylenediamine tetrakis (methylene phosphonic acid) and diethylene triamine penta (methylene phosphonic acid). The chelating agents can be used alone or in combination of two or more.

(Other ingredients)
The polishing composition disclosed herein may be selected from surfactants, organic acids, organic acid salts, inorganic acids, inorganic acid salts, preservatives, fungicides, etc., as long as the effects of the present invention are not significantly impaired. If necessary, known additives that can be used for the polishing slurry may be further contained. The polishing slurry is typically a polishing slurry used in a polishing process of a silicon substrate.

The polishing composition disclosed herein preferably contains substantially no oxidizing agent. When an oxidizing agent is contained in the polishing composition, the polishing slurry is supplied to the object to be polished (here, a 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 be reduced. Specific examples of the oxidizing agent referred to herein include hydrogen peroxide (H ₂ O ₂ ), sodium persulfate, ammonium persulfate, sodium dichloroisocyanurate and the like. In addition, that a polishing composition does not contain an oxidizing agent substantially means that an oxidizing agent is not included at least intentionally.

  The pH of the polishing composition in the art 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. The pH of the polishing composition in a further preferred embodiment is, for example, 10.0 or more. As the pH of the polishing solution increases, the polishing rate tends to improve. The upper limit value of the pH of the polishing liquid is not particularly limited, but it is preferably 12.0 or less, for example, 11.5 or less, more preferably 11.0 or less, from the viewpoint of polishing the object to be polished better. . From the viewpoint of surface quality improvement, 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, typically 10.5 or less. The surface quality improvement typically refers to surface roughness reduction. The above pH can be preferably employed, for example, in a polishing solution used for polishing a silicon wafer. The polishing solution is, for example, a polishing solution for rough polishing.

  In the technique disclosed herein, the pH of the liquid composition is adjusted using a pH meter and calibrated at three points using a standard buffer, and then the glass electrode is put in the composition to be measured, 2 It can be grasped by measuring the value after the lapse of more than a minute and becoming stable. The liquid composition may be polishing slurry, solution A, solution B, etc., a concentrate thereof, etc. Moreover, as a pH meter, for example, a glass electrode type hydrogen ion concentration indicator manufactured by Horiba, Ltd. (model number F-23) is used. Furthermore, the standard buffer is 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.).

<Method of producing polishing composition>
The polishing composition disclosed herein can be produced by the following method. Specifically, in the above-mentioned production method, a step of preparing a solution A containing abrasive grains and a basic compound (a solution A preparation step) and a solution B containing a water-soluble polymer P1 having an inertial radius of 100 nm or more are prepared. And a step of mixing the solution A and the solution B (mixing step). The order of the A solution preparation step and the B solution preparation step is not particularly limited.

(Liquid A preparation process)
In producing the polishing composition disclosed herein, a solution A containing abrasive grains and a basic compound is prepared. As a kind of abrasives contained in A liquid, 1 type, or 2 or more types of various abrasives illustrated as an abrasive which may be contained in the composition for grinding | polishing can be used. Examples of various abrasives include silica particles, preferably colloidal silica. Similarly, the average primary particle size, shape, and average aspect ratio of the abrasive grains can also be the average primary particle size, 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 the components at a higher concentration than the polishing composition, from the viewpoint of convenience such as production, distribution, storage, and the like. Therefore, it is preferable that the content of abrasive grains in the solution A is also higher than the content of abrasive grains in the polishing composition. Specifically, the content of abrasive grains in the solution 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, and further Preferably it is 25 weight% or more. From the viewpoint of stability, filterability, etc., the content of the abrasive grains in the solution A is, for example, suitably 50% by weight or less, 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, and 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 solution A, but the technology disclosed herein is not limited thereto. A part of the abrasive grains contained in the polishing composition may be contained in the solution A as long as the effects of the present invention are not significantly impaired. Specifically, when the total amount of abrasive grains contained in the polishing composition is 100% by weight, it is appropriate that the amount exceeding 50% by weight is contained in the solution A, and the polishing composition Preferably, 80% by weight or more, for example, 90% by weight or more, further 95% by weight or more, typically 99% by weight to 100% by weight of the total amount of abrasive grains contained in the solution A is contained.

As to the basic compound contained in solution A, one or two or more of various basic compounds exemplified as the basic compound which can be contained in the polishing composition can be used as in the case of the abrasive grains. . A quaternary ammonium compound, a weak acid salt, or a combination of both is preferred. When the solution B 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 to the weak acid salt in the solution B is not particularly limited. Grade ammonium compounds: It is appropriate to make the weak acid salt 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 solution A is, for example, 0.1% by weight or more, typically 0.5% by weight or more, from the viewpoint of improving the polishing rate, etc. It is 1% by weight or more, more preferably 1.5% by weight or more, and further preferably 2.0% by weight or more. In a further preferred embodiment, the content of the basic compound in the solution A is, for example, 2.5% by weight or more. For example, when the solution A is used after being diluted at a high magnification, the concentration of abrasive grains after dilution may be relatively low, and the processing power of the abrasive grains may also tend to decrease. Even in such a case, chemical polishing after dilution can be enhanced by increasing the amount of the basic compound at the stage of solution A. The upper limit of the content of the basic compound in the solution A is suitably 10% by weight or less, preferably 5% by weight or less, from the viewpoint of storage stability, surface quality and the like. In a preferred embodiment, the content of the basic compound in the solution A is, for example, 3% by weight or less.

  In addition, 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 solution A is suitably 0.1 parts by weight or more based on 100 parts by weight of the abrasive, and preferably 1 weight from the viewpoint of improving the polishing rate, etc. The amount is preferably at least 3 parts by weight, more preferably at least 6 parts by weight. Further, from the viewpoint of stability, surface quality, etc., 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 the abrasive grains. It is 15 parts by weight or less, more preferably 12 parts by weight or less.

  In the technology disclosed herein, the entire amount of the basic compound contained in the polishing composition may be contained in solution A, or a part thereof may be contained in solution A. Specifically, when the total amount of basic compounds contained in the polishing composition is 100% by weight, it is appropriate that the amount exceeding 50% by weight is contained in the solution A, and the polishing composition is Preferably, 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 liquid A is contained. A mode in which part of the basic compound contained in the polishing composition is contained in liquid A and the remainder is contained in liquid B described below from the viewpoint of reducing the pH difference with liquid B when mixing with liquid B described later Is preferably employed. In this aspect, the amount of the basic compound contained in the solution A is 99.999% by weight or less, for example 99.99% by weight or less, based on 100% by weight of the total amount of basic compounds contained in the polishing composition. Typically, it may be as low as 99.9% by weight or less.

When the polishing composition disclosed herein contains the water-soluble polymer P2 described above, it is preferable to include the water-soluble polymer P2 in solution A in the production of the polishing composition. This tends to improve the dispersion stability of the abrasive grains. As the water-soluble polymer P2 which can be contained in the solution A, one or more of various water-soluble polymers P2 exemplified as the water-soluble polymer P2 which can be contained in the polishing composition can be used. When the solution A contains the water-soluble polymer P2, the content (concentration) of the water-soluble polymer P2 in the solution A is 1 × 10 ⁻⁴ wt% from the viewpoint of sufficiently obtaining the addition effect of the water-soluble polymer P2. It is suitable to set it as the above, Preferably it is 1 * 10 < ^-3 > weight% or more. In a preferred embodiment, the content of the water-soluble polymer P2 in the solution A is, for example, 3 × 10 ⁻³ wt% or more. The upper limit of the content of the water-soluble polymer P2 in the solution A is not particularly limited, and for example, 1 × 10 ⁻¹ wt% or less, typically 1 × 10 ⁻² wt% or less is suitable. When the polishing composition contains the water-soluble polymer P2, the entire amount of the water-soluble polymer P2 may be contained in the liquid A, a part thereof is contained in the liquid A, and the remaining part is contained in the liquid B. The entire amount may be contained in solution B.

  The technology disclosed herein can be preferably carried out 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 solution A. In addition, the above-mentioned solution A can typically contain an aqueous solvent represented by water. Liquid A is added with a chelating agent, surfactant, organic acid, organic acid salt, inorganic acid, inorganic acid salt, preservative, antifungal agent, etc. that can be contained as an optional component in the polishing composition disclosed herein. The agent may further contain as required.

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

  The method for preparing the solution A is not particularly limited. For example, it is good to mix each component contained in A liquid using well-known mixing apparatuses, such as a wing | blade type | formula stirrer, an ultrasonic dispersion machine, a homomixer. The aspect which mixes these components is not specifically limited, For example, all the components may be mixed at once, and you may mix in the order set suitably. The same mixing method may be appropriately adopted for the solution B described later.

(Liquid B preparation process)
The solution B used for producing the polishing composition disclosed herein contains a water-soluble polymer P1 having a radius of inertia of 100 nm or more. As the water-soluble polymer P1 contained in the solution B, one or more of various water-soluble polymers exemplified as the water-soluble polymer P1 which can be contained in the polishing composition can be used.

  Similarly to solution A, solution B is also typically prepared in a form containing the components at a higher concentration than the polishing composition, from the viewpoint of convenience such as production, distribution, storage, and the like. Therefore, the content of the water-soluble polymer P1 in the solution 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 solution 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 B liquid 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 solution B is suitably 10 wt% or less, for example, and preferably 3 wt% or less. In a preferred embodiment, the content of the water-soluble polymer P1 in the solution B is, for example, 1% by weight or less, and typically 0.5% by weight or less.

  In a preferred embodiment, the entire amount of the water-soluble polymer P1 contained in the polishing composition is contained in the solution B from the viewpoint of stability, but the technology disclosed herein is not limited thereto. A part of the water-soluble polymer P1 contained in the polishing composition may be contained in the solution 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 the amount exceeding 50% by weight is contained in the solution B, and the polishing is performed. It is preferable to include in the solution B 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.

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

  In addition, when the polishing composition disclosed herein contains the water-soluble polymer P2, the whole or a part of the water-soluble polymer P2 may be contained in the solution B. In this case, the radius of inertia of all the water-soluble polymers contained in the solution B may be less than 100 nm, but the solution B is also contained in the solution B even when the solution B contains the water-soluble polymer P2 and naturally The radius of inertia of all the water-soluble polymers is preferably 100 nm or more. In a more preferable aspect, the radius of inertia of all the water-soluble polymers contained in the solution 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 all the water-soluble polymers contained in solution B is not particularly limited, and it is suitably about 500 nm or less, preferably 300 nm or less, from the viewpoint of the stability of solution B, concentration efficiency, etc. More preferably, it may be 250 nm or less, more preferably 220 nm or less, or about 150 nm or less, for example, 120 nm or less.

  Although the technology disclosed herein can be preferably carried out in a mode in which the solution B substantially does not contain abrasive grains, one of the abrasive grains contained in the polishing composition, as long as the effects of the invention are not significantly impaired. Part may be included in the solution B. Further, the solution B may contain an aqueous solvent represented by water. The solution B contains a chelating agent, surfactant, organic acid, organic acid salt, organic acid, inorganic acid, inorganic acid salt, preservative, antifungal agent, etc., which can be optionally contained in the polishing composition disclosed herein. The agent may further contain as required.

  The pH of the solution B disclosed herein is not particularly limited. From the viewpoint of suppressing the pH change at the time of mixing with the solution A, the pH of the solution B is suitably within ± 3 of the pH of the solution A, preferably within ± 2 and 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)
Next, the solution A and solution B prepared as described above are mixed. The method of mixing is not particularly limited, and if necessary, it may be carried out using a known and conventional mixing apparatus. The timing of the above mixing is not particularly limited, and it is preferable to mix the solution A and the solution B 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, ie, polishing. The period from the above 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 preferable to set it within 24 hours starting the polishing using the above-mentioned polishing composition, typically within 12 hours, immediately before the start of polishing, It is more preferable to carry out the mixing step, for example within 6 hours, typically within 3 hours. Alternatively, the produced polishing composition may be supplied to the object to be polished while continuously mixing the solution A and the solution B.

  The mixing ratio of the solution A and the solution B is appropriately set so that the composition of the polishing composition falls within a desired range. In a preferred embodiment, in the mixing step, solution A: solution 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. Be mixed.

  In a preferred embodiment, dilution is performed using an aqueous solvent such as water before and / or simultaneously with the mixing of the solution A and the solution B. By performing dilution at this timing, the advantages and stability of the concentrate can be compatible in the state of the liquid A and the liquid B before using the polishing composition. The advantages of the concentrate are convenience, cost reduction, etc. Moreover, the polishing composition obtained by performing dilution can exhibit the outstanding edge roll off reduction effect. In one particularly preferred embodiment, the solution A, the solution B and the dilution aqueous solvent are mixed substantially simultaneously or continuously mixed. When the solution A, the solution B, and the dilution aqueous solvent are continuously mixed, the order of addition is not particularly limited. In order to reduce the influence of pH change due to mixing, it is preferable to adopt an embodiment in which the solution A is diluted with an aqueous solvent for dilution and then the solution B is added to the diluted solution A. As the liquid used for dilution, it is preferable to use an aqueous solvent substantially consisting of water from the viewpoint of handleability, workability and the like. The water is typically ion exchanged 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 and diluted, and a mixture containing those components in an amount ratio different from that of the aqueous solvent The solvent may be added and diluted.

  It is appropriate that the dilution ratio by the aqueous solvent for dilution is a ratio larger than 2 times on a volume basis with respect to the total amount of the solution A and the solution B. By diluting at the above magnification, a polishing composition having a composition suitable for polishing can be obtained from the concentrated solutions A and B. According to the technology disclosed herein, the dilution may be performed with a magnification greater than 10 times, typically 15 times or more, for example 25 times or more on a volume basis, based on the total amount of the A and B liquids. 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 mixed solution of solution A and solution B itself may 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 to a magnification ratio (concentration ratio) of over 2 times on a volume basis. The concentration factor may be preferably greater than 10 times by volume, typically 15 times or more, for example 25 times or more.

  There are no particular limitations on the method of mixing solution A, solution B, and an aqueous solvent for dilution, which is optionally used. If necessary, for example, the liquid may be mixed using a known mixing device such as a wing stirrer, an ultrasonic disperser, a homomixer or the like. 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 addition, in the production of the polishing composition disclosed herein, one or more additional agents (Liquid C) containing a part of the components included in the polishing composition in addition to the A solution and the B solution. , D, etc.) may be mixed as an optional component.

<Composition Set for Polishing>
The polishing composition set disclosed herein is a multi-component type polishing composition set used to produce the above-described polishing composition, and comprises at least the above-described A solution and B solution. The solution A contains at least abrasive grains and a basic compound, and the solution B contains at least a water-soluble polymer P1. The polishing composition set according to a preferred embodiment is a two-component set comprising solution A and solution B. In addition, since the detail of A liquid and B liquid is as above-mentioned, the overlapping description is not repeated here. In addition, the polishing composition set disclosed herein includes one or more additional agents (C solution, D, and the like) which contain a part of the components contained in the polishing composition in addition to the A solution and the B solution. A liquid or the like may be referred to as “3. The above-mentioned solution A, solution B and optional additional agent are typically stored in separate containers until the mixing step in the production of the polishing composition.

<Use>
The technology disclosed herein is preferably applied to polishing using a silicon substrate (particularly a silicon wafer) as a polishing target. A typical example of the silicon wafer mentioned 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 technology disclosed herein is typically a surface made of silicon.

  Before the polishing process using the polishing liquid disclosed herein, the silicon substrate is subjected to a general process that can be performed on the silicon substrate in the process upstream of the rough polishing process, such as lapping and etching. May be Further, in the technology disclosed herein, after the polishing step (rough polishing step) using the polishing liquid, a finish polishing step may be performed on the silicon substrate. The finishing process includes one or more polishing processes, and through final polishing, the silicon wafer is finished to a high quality mirror surface. In addition, final polishing refers to the last polishing process in the manufacturing process of an object. That is, final polishing refers to a step in which no further polishing is performed after the step. Therefore, the polishing solution, solution A and solution B disclosed herein can be used for polishing a silicon wafer that has undergone lapping. In addition, the above-mentioned polishing liquid and the like can be used for rough polishing performed before final polishing of a silicon wafer. Rough polishing is also referred to as preliminary polishing.

<Polishing>
The polishing of the object to be polished can be performed, for example, as follows. That is, using the production method disclosed herein, specifically, the A solution preparation step, the B solution preparation step, and the mixing step of the A solution and the B solution are carried out, and dilution is carried out as necessary. Then, a polishing composition (polishing slurry) is prepared. Then, the polishing slurry (working slurry) is supplied to a polishing object and polished by a conventional method. In rough polishing of a silicon wafer, typically, the object to be polished (silicon wafer) subjected to the lapping process is set in a polishing apparatus, and the above-described polishing pad is fixed through the polishing pad fixed on the platen of the polishing apparatus. A polishing slurry is supplied to the surface of the object to be polished (surface to be polished). Typically, while the polishing slurry is continuously supplied, the polishing pad is pressed against the surface of the object to be moved relative to each other. Polishing of the object to be polished is completed through this polishing process. The movement is, for example, rotational movement.

  The polishing pad used in the polishing step is not particularly limited. For example, polishing pads of foamed polyurethane type, non-woven type, suede type, etc. can be used. Each polishing pad may or may not include abrasive grains.

  As a polishing apparatus, a double-sided polishing apparatus that simultaneously polishes both surfaces of an object to be polished may be used, or a single-side polishing apparatus may be used to polish only one surface of the object to be polished. Although not particularly limited, for example, a double-side polishing apparatus can be preferably employed in the rough polishing process. The double-sided polishing apparatus is, for example, a batch-type double-sided polishing apparatus. The polishing apparatus may be a single-wafer 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 platen. May be.

  Although not particularly limited, it is preferable that the polishing composition produced using the set disclosed herein be used for polishing within a relatively short period of time after its production. This makes it possible to better take advantage of the multi-component type, i.e., the configuration having a plurality of agents, for producing the polishing composition. The period from preparation to use of the polishing composition can be, for example, within 2 weeks, suitably within 3 days, preferably within 24 hours, and within 12 hours. More preferable. The above period may be 6 hours or less, or 3 hours or less. Alternatively, the produced polishing composition may be supplied to the object to be polished while continuously producing the above-mentioned polishing composition using a set.

  The above-mentioned polishing composition may be used in a disposable form once it has been used for polishing, so-called "deep flow", or may be used repeatedly in circulation. As an example of a method of circulating and using the polishing composition, there is a method of recovering the used polishing composition discharged from the polishing apparatus into a tank and supplying the recovered polishing composition to the polishing apparatus again. . When the polishing composition is used in circulation, the environmental load can be reduced by reducing the amount of the used polishing composition to be treated as a waste solution, as compared to the case of using it in a pouring-on process. Moreover, cost can be held down by reducing the amount of polishing composition used. The polishing composition disclosed herein is suitable for the mode of use thus recycled because it is excellent in pH maintainability. According to such a mode of use, the significance of adopting the configuration of the present invention can be particularly well exhibited. When the polishing composition disclosed herein is used cyclically, it is possible to add a new component, a component reduced by use or a component desired to be increased at any time to the polishing composition in use. Good.

<Washing>
The object to be polished after the rough polishing process is typically cleaned before starting the finish polishing process. This washing can be performed using a suitable washing solution. The cleaning solution to be used is not particularly limited, and, for example, SC-1 cleaning solution, SC-2 cleaning solution and the like generally used 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 mixture of HCl, H ₂ O ₂ and H ₂ O. The temperature of the cleaning solution can be, for example, in the range of about room temperature or higher to about 90 ° C. or so. Here, room temperature typically refers to about 15 ° C to 25 ° C. From the viewpoint of improving the washing effect, a washing solution of about 50 ° C. to 85 ° C. can be preferably used.

  Polishing of the object to be polished is completed through the above-described rough polishing process, cleaning process, and finish polishing process. The object to be polished is here a silicon substrate, typically a silicon single crystal wafer. Therefore, according to this specification, there is provided a method of producing an abrasive, comprising the above-mentioned polishing step. Specifically, the above-mentioned manufacturing method is a manufacturing method of a silicon wafer.

  As mentioned above, according to this embodiment, the method of manufacturing the composition for silicon wafer rough polish containing an abrasive grain, a basic compound, and a water-soluble polymer is provided. This manufacturing method comprises: preparing A solution containing the abrasive grains and the basic compound; and preparing B solution 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 solution A and the solution B. The polishing composition obtained by such a method can improve the edge roll-off in the polishing of the silicon substrate by including the water-soluble polymer P1 having a predetermined radius of inertia or more. Moreover, the polishing composition before completion, in other words, before use is a multi-component type having solution A and solution B, and concentration, such as convenience and cost reduction, is achieved by increasing the concentration of each solution (condensing liquefaction) You can enjoy the benefits of liquid. Further, since the abrasive grains and the water-soluble polymer P1 are separately contained in the solution A and the solution B, it is possible to avoid an event that the dispersion of the water-soluble polymer P1 is inhibited by the presence of the abrasive grains. As a result, the polishing composition before completion exhibits excellent stability in the state of solution A and solution B. Therefore, according to the present invention, it is possible to manufacture a silicon wafer rough polishing composition which is excellent in stability and can improve edge roll-off while enjoying the advantage of a concentrate.

  A preferred embodiment of the technology disclosed herein comprises the step of diluting at least one of the solution A, the solution B, and a mixture of the solution A and the solution B. In addition, the dilution ratio in the dilution step is a ratio larger than 10 times on a volume basis with respect to the total amount of the solution A and the solution B. By adopting such a method, the polishing composition before completion can achieve both the advantage and stability of the concentrate, and the polishing composition in which the solution A and the solution B are mixed at the time of use As a result, the edge roll off reduction effect can be exhibited. The advantages of the concentrate are convenience, cost reduction, etc. The dilution step may be performed before, simultaneously with or after the step of mixing the solution A and the solution B. In the present specification, the technology disclosed herein includes a method for producing a silicon wafer rough polishing composition, a silicon wafer rough polishing composition set, a silicon wafer polishing method, and the like.

  In a preferred embodiment of the technology disclosed herein, the radius of inertia of the water-soluble polymer contained in the solution B is 100 nm or more. By preparing the solution B, storing it as necessary, and mixing it with the solution A when using the polishing composition, the effects of the technology disclosed herein are preferably exhibited.

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

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

  Further, according to the present embodiment, 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. The polishing composition set includes solution A containing the abrasive grains and the basic compound, and solution B containing a water-soluble polymer P1 having a radius of inertia of 100 nm or more as the water-soluble polymer. According to this configuration, before use, for example, at the time of storage, when each of solution A and solution B is used as a concentrate, it is excellent in stability while taking advantage of the concentrate. Then, the solution A and the solution B are mixed at an appropriate timing to form a polishing composition (polishing slurry), and by using this, the edge roll-off of the silicon substrate can be improved. The advantages of the concentrate are convenience, cost reduction, etc.

  Further, according to the present embodiment, there is provided a silicon wafer polishing method including a rough polishing step and a finish polishing step. This polishing method includes the step of preparing a crude polishing composition to be used in the rough polishing step before the rough polishing step. Further, the step of preparing the rough polishing composition comprises the steps of: preparing A solution containing abrasive grains and a basic compound; and preparing B solution containing a water-soluble polymer P1 having an inertial radius of 100 nm or more. And a step of mixing the solution A and the solution B. According to this method, the polishing composition before use can be made into a concentrate having excellent stability in the state of being separated into the solution A and the solution B. In addition, by performing rough polishing using the polishing composition, edge roll-off of a silicon substrate can be improved.

  In one typical aspect 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 (pre-polishing) performed before final polishing of a silicon wafer.

  The following examples illustrate some of the embodiments of the present invention, but are not intended to limit the present invention to those shown. In the following description, “%” is on a weight basis unless otherwise noted.

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

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

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

Example 5
By mixing colloidal silica (average primary particle diameter 55 nm) as abrasive grains, TMAH, K ₂ CO ₃ , and ion-exchanged water, the abrasive grains, TMAH and K ₂ CO ₃ are each 32.97%, Solution A was prepared at concentrations of 1.62% and 1.05%. The pH of solution A was 11.2.
Further, by mixing water-soluble polymer P1 (HEC), water-soluble polymer P2 (PVP Mw 4.5 × 10 ⁴ ), TMAH, and ion-exchanged water, water-soluble polymer P1, high water-soluble polymer A solution B was prepared containing molecules P2 and TMAH at concentrations of 0.25%, 0.28% and 0.018%, respectively. The pH of the B liquid 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
A 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 solution B was changed to 0.011% of potassium hydroxide (KOH) in Example 3. .

<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 ), By mixing with ion-exchanged water, concentrates (one-component type) of polishing compositions according to Comparative Examples 2 to 5 were prepared. The concentrations of abrasive grains, water-soluble polymer P1, TMAH, K ₂ CO ₃ and water-soluble polymer P 2 in the concentrate of each example are 32.97%, 0.0061%, 1.62%, 1.05, respectively. % And 0.0069%.
The obtained concentrate was diluted with ion exchange water to obtain a polishing liquid (working slurry) according to the present example. The above dilution was carried out so that the ratio of concentrate: ion exchange 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.

[Method of measuring the radius of inertia]
In the measurement of the radius of inertia 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- The measurement was performed every 10 degrees in the range of a measurement angle of 20 to 150 degrees using "8000" (manufactured by Otsuka Electronics Co., Ltd.), and the inertial radius [nm] was calculated by monotonic plot analysis. The measurement was performed on the water-soluble polymer P1 and the water-soluble polymer contained in the solution B. When a plurality of water-soluble polymers were contained in the solution B, the measurement was carried out by adjusting the water-soluble high molecular weight so as to obtain the concentration ratio. The measurement results are shown in Table 1.

[Stability]
100 g of each of the solutions A and 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 separately stored at 25 ° C. for storage. Moreover, the concentrate which concerns on Comparative Examples 2-6 was stored on the said, same conditions. The state of the solution A, the solution B and the concentrate after 24 hours from the start of storage was visually evaluated according to the following 2 criteria. That is, it was evaluated as "A" when separation or aggregation of components in the liquid was not observed, and was evaluated as "B" when separation or aggregation was observed. The results are shown in Table 1.

Polishing of silicon wafers
Rough polishing was performed using the polishing liquid (working slurry) according to each example under the following conditions.
(Polishing conditions)
Polishing device: Single-side polishing device manufactured by Nihon Engis, model "EJ-380IN"
Polishing pad: manufactured by Nitta Hearth, trade name "MH S-15A"
Polishing pressure: 26.6 kPa
Slurry flow rate: 100 mL / min Plate rotational speed: 50 rpm
Head rotation speed: 50 rpm
Polishing amount: 8 μm
Work species: Bare Si ^P - <100>
Work size: □ 60 mm × 60 mm

Edge roll off
Using a non-contact surface shape measurement machine (trade name “NewView 5032”, manufactured by Zygo, available from Canon Inc.), determine the reference height from the center (20 mm square from the center) of the surface of the polishing object after the above polishing A change in height at a position about 2.5 mm from the outer peripheral end of the abrasive was measured, and this was taken as the amount of edge roll-off. The measured edge roll-off amount was evaluated based on the following four criteria.
A: Edge roll off amount less than 250 nm B: Edge roll off amount 250 nm to less than 280 nm C: Edge roll off amount 280 nm to less than 300 nm D: Edge roll off amount 300 nm or more A to C are practically acceptable levels, D not acceptable I considered it a pass. The results are shown in Table 1.

[Surface roughness Ra]
Non-contact surface shape measuring machine (brand name "NewView 5032", manufactured by Zygo, available from Canon Inc.) for the silicon wafer after rough polishing according to each example (roughly polished and thereafter cleaned test specimen) Surface roughness Ra (arithmetic mean surface roughness) was measured. The obtained measured value was converted into a relative value with the surface roughness Ra of Example 4 being 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 solution A containing abrasive grains and a basic compound and solution B containing water-soluble polymer P1 were separately prepared, both solutions A and B had stability. It was excellent. On the other hand, in Comparative Examples 3 to 6 in which a single-component concentrate was used, good stability could not be obtained. Further, in Examples 1 to 6 using the water-soluble polymer P1 having a radius of inertia of 100 nm or more, the edge roll-off is improved as compared with Comparative Examples 1 and 2 using a water-soluble polymer having a radius of inertia of less than 100 nm. It was done. Furthermore, in Examples 1 to 3, 5 and 6 in which the water-soluble polymer P2 was used in combination, the surface roughness Ra also tended to be improved compared to Example 4 in which the water-soluble polymer P2 was not used. The

  As mentioned above, although the specific example of this invention was described in detail, these are only an illustration and do not limit a claim. The art set forth in the claims includes various variations and modifications of the specific examples illustrated above.

Claims (7)

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