WO2016035250A1 - Method for manufacturing polishing composition - Google Patents

Abstract

The purpose of the present invention is to provide a method for manufacturing a polishing composition for which dispersion stability as an undiluted solution is good and which even when diluted, for example, at a high ratio, is able to achieve good surface quality. A method for manufacturing a polishing composition is provided. Said manufacturing method comprises a step for diluting an undiluted polishing composition solution containing abrasive grains, a basic compound, a water-soluble polymer, and water so that the pH change is at least 0.15. For the undiluted polishing composition solution, an index (A) determined from the relational expression: (A) = [(CA) x (CP)]/(pHC) (in the relational expression, (CA) is the content (mass%) of abrasive grains in the undiluted polishing composition solution, (CP) is the content (mass%) of water-soluble polymer in the undiluted polishing composition solution, and (pHC) is the pH value of the undiluted polishing composition solution) is not more than 0.8. The molarity of the water-soluble polymer in the polishing composition after the dilution is at least 7.0 x 10^-8 moles/L.

Description

Method for producing polishing composition

The present invention relates to a method for producing a polishing composition. Specifically, the present invention mainly relates to a method for producing a polishing composition that is preferably used for polishing a semiconductor substrate such as a silicon wafer and other polishing objects.

Polishing using a polishing liquid (typically precision polishing) is performed on the surface of materials such as metal, metalloid, nonmetal, and oxides thereof. For example, the surface of a silicon wafer used as a component of a semiconductor product is generally finished to a high-quality mirror surface through a lapping process (rough polishing process) and a polishing process (precision polishing process). The polishing process typically includes a preliminary polishing process (preliminary polishing process) and a final polishing process (final polishing process). This type of polishing composition is in a concentrated form (that is, a concentrated liquid for polishing liquid) before being supplied to the object to be polished from the viewpoint of convenience, cost reduction, etc. during manufacture, distribution, storage, etc. (Hereinafter also referred to as “stock solution”). A concentrated solution prepared as a stock solution is diluted with water or the like and then used as a polishing solution for polishing. Patent Documents 1 to 3 are listed as technical documents disclosing this type of prior art.

JP 2014-90100 A Japanese Patent Laid-Open No. 2014-41978 JP 2013-34026 A

The above-mentioned polishing composition stock solution typically contains components such as abrasive grains and a water-soluble polymer at a higher concentration than ordinary polishing liquids. Therefore, depending on the component concentration (concentration degree) of the stock solution, the component tends to aggregate, and there is a possibility that good dispersion stability (stability of the dispersion state of the components in the stock solution) may not be obtained. For example, a stock solution used after diluting at a high magnification tends to have a high concentration, so that the dispersion stability tends to be significantly reduced. In addition, since the component concentration basically decreases in conjunction with the dilution ratio, there is a possibility that the role that the component should play is not fully exhibited depending on the degree of dilution. For example, when the amount of the water-soluble polymer is lowered, it tends to be difficult to obtain good surface quality (for example, a low haze surface). For these practical reasons, the dilution ratio of the stock solution is usually limited within a reasonable range. It is further noted that the pH can also vary depending on the dilution method (eg dilution factor). The pH can be a factor affecting dispersion stability in the stock solution. After dilution, the chemical mechanical polishing (CMP) method based on the interaction between the abrasive grains and the basic compound affects the polishing rate and surface quality. Can be an important factor. Polishing satisfying the dispersion stability in the stock solution and the polishing performance after dilution (for example, the surface quality such as polishing rate and haze) in the aspect of diluting at a high magnification, for example, from the above pH and other various circumstances to be considered The present condition is that the composition for use is not yet realized.

The present invention was created in view of the above circumstances, and is a polishing composition that has good dispersion stability when used as a stock solution and that can achieve good surface quality even when diluted at a high magnification, for example. It aims at providing the manufacturing method of a thing.

According to the present invention, a method for producing a polishing composition is provided. This manufacturing method includes a step of diluting a polishing composition stock solution containing abrasive grains, a basic compound, a water-soluble polymer, and water so that the pH change is 0.15 or more. The polishing composition stock solution is a relational expression: A = [CA × CP] / pHC (in the relational expression, CA is the content (% by weight) of abrasive grains in the polishing composition stock solution, and CP is for polishing. The content (% by weight) of the water-soluble polymer in the composition stock solution, and the pH A is the pH value of the polishing composition stock solution. The molar concentration of the water-soluble polymer in the polishing composition after dilution is 7.0 × 10 ⁻⁸ mol / L or more.

In the polishing composition stock solution, the index A is limited to a predetermined value or less as described above. Here, the index A being not more than a predetermined value means that the upper limit of the product of the content of abrasive grains and the content of water-soluble polymer is not more than a predetermined value in relation to the stock solution pH value that can contribute to dispersibility. It means that it is limited to. Briefly, it means that the content of abrasive grains and water-soluble polymer that can be coagulation factors is limited under a predetermined pH condition or more. Since the index A having such a technical meaning is limited to a predetermined value or less, components such as abrasive grains and water-soluble polymers can maintain a stable dispersion state in the stock solution. In addition, the number of molecules of the water-soluble polymer after dilution is maintained at a predetermined value or more despite the above quantitative limitations before dilution. Therefore, even in an embodiment in which dilution (dilution in which the pH change becomes a predetermined value or more) in which the state change between the undiluted undiluted solution and the composition after dilution becomes significant (preferably a change in pH), the presence of the water-soluble polymer allows good surface quality (typical Specifically, a low haze surface) can be realized. Therefore, according to the production method of the present invention, it is possible to realize a polishing composition that has good dispersion stability when used as a stock solution and that can realize good surface quality even when diluted at a high magnification, for example.

In a preferred embodiment of the technology disclosed herein, the dilution step is performed using a liquid that does not substantially contain a basic compound. By adopting such a dilution method, it is possible to preferably carry out dilution such that the pH change becomes a predetermined value or more.

In a preferred aspect of the technology disclosed herein, the dilution step is a step of diluting the polishing composition stock solution so that the pH change is 0.3 or more. As described above, in a mode in which the pH change before and after dilution is large, by applying the technique disclosed herein, it is possible to realize good surface stability after dilution and good dispersion stability in the case of a stock solution. A polishing composition is preferably realized.

In a preferred aspect of the technology disclosed herein, the dilution step is a step of diluting the polishing composition stock solution 50 times or more on a volume basis. The stock solution diluted and used at such a high magnification tends to have a high concentration of the components contained therein, so that the components are likely to aggregate and it is difficult to obtain good dispersion stability. In such a configuration, the stock solution can exhibit good dispersion stability by designing the stock solution composition so that the index A is a predetermined value or less. In addition, as the dilution factor increases, the pH change before and after dilution also increases, and it tends to be difficult to achieve both dispersion stability before dilution and surface quality by the composition after dilution. In the aspect of diluting to the above magnification while maintaining the dispersion stability before dilution, the surface concentration (typically low haze surface) is excellent. This can be realized particularly preferably. Achieving a desired effect (for example, compatibility between polishing rate and surface quality) with the polishing liquid diluted at the above magnification is particularly advantageous from the viewpoint of cost reduction, and the practical advantage is great.

In a preferred embodiment of the technology disclosed herein, the diluted polishing composition has a pH of 8-12. Thereby, a good polishing rate can be preferably realized. In this embodiment, the pH change due to dilution is a change in which the pH decreases.

In a preferred embodiment of the technology disclosed herein, silica abrasive grains are used as the abrasive grains. According to the technique disclosed herein, in the embodiment using silica abrasive grains as the abrasive grains, both the dispersion stability of the stock solution and the surface quality after polishing are preferably realized.

In a preferred embodiment of the technology disclosed herein, the water-soluble polymer has a weight average molecular weight of 90 × 10 ⁴ or less. When the weight average molecular weight (Mw) of the water-soluble polymer is not more than a predetermined value, the dispersion stability of the stock solution is further improved, and good surface quality (typically haze reduction) is easily obtained.

In a preferred embodiment of the technology disclosed herein, the polishing composition is used for polishing a silicon wafer. The polishing composition produced by the method disclosed herein is preferably used for polishing a silicon wafer that has undergone lapping, for example. Among these, it is particularly preferably used for final polishing of a silicon wafer.

Moreover, according to this invention, the polishing composition undiluted | stock solution used by diluting so that pH change may be set to 0.15 or more is provided. This stock solution contains abrasive grains, a basic compound, a water-soluble polymer and water. Further, the relational expression: A = [CA × CP] / pHC (in the relational expression, CA is the content (% by weight) of abrasive grains in the polishing composition stock solution, and CP is water-soluble in the polishing composition stock solution). Polymer A content (% by weight), and pHC is the pH value of the polishing composition stock solution.); Further, the molar concentration of the water-soluble polymer is 4.3 × 10 ⁻⁶ mol / L or more. The polishing composition stock solution having the above structure exhibits good dispersion stability because the index A is limited to a predetermined value or less. In addition, since the polishing composition stock solution contains a sufficient amount of water-soluble polymer even after dilution, according to polishing using the diluted composition, good surface quality (typically Can realize a low haze surface).

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.

<Containing components of polishing composition stock solution and polishing composition>
The polishing composition stock solution in the technology disclosed herein contains abrasive grains, a basic compound, a water-soluble polymer, and water. Moreover, various additives can be contained as needed. Similarly, the polishing composition prepared by diluting the stock solution contains abrasive grains, a basic compound, a water-soluble polymer, and water, and may contain various additives as optional components.

(Abrasive grains)
In the technology disclosed herein, the material and properties of the abrasive grains contained in the polishing composition stock solution and the polishing composition diluted with the stock solution are not particularly limited, and are appropriately selected according to the purpose of use, use mode, and the like. be able to. 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 and poly (meth) acrylic acid particles (here, (meth) acrylic acid is a generic term for acrylic acid and methacrylic acid). 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.

As the abrasive, inorganic particles are preferable, and particles made of metal or metalloid oxide are particularly preferable. In the technology disclosed herein, particularly preferable abrasive grains include silica particles. Silica particles can exhibit excellent dispersibility in high pH stock solutions. Further, for example, when applying the technique disclosed herein to a polishing composition that can be used for polishing a silicon wafer, it is particularly preferable to use silica particles as abrasive grains. The reason is as follows. That is, when the object to be polished is a silicon wafer, if silica particles composed of the same elements and oxygen atoms as the object to be polished are used as abrasive grains, no metal or metalloid residue different from silicon is generated after polishing. There is no risk of contamination on the surface of the silicon wafer or deterioration of electrical characteristics of the silicon wafer due to diffusion of a metal or metalloid different from silicon into the object to be polished. Furthermore, since the hardness of silicon and silica is close, polishing can be performed without undue damage to the silicon wafer surface. A polishing composition containing only silica particles as abrasive grains is exemplified as a preferred polishing composition from such a viewpoint. Silica has a property that it can be easily obtained in high purity. This is also cited as the reason why silica particles are preferable as the abrasive grains. Specific examples of the silica particles include colloidal silica, fumed silica, precipitated silica and the like. Colloidal silica and fumed silica are preferable as silica particles from the viewpoint that scratches are hardly generated on the surface of the object to be polished and a surface having a lower haze can be realized. Of these, colloidal silica is preferred. For example, colloidal silica can be preferably employed as the abrasive grains of the polishing composition used for polishing (particularly final polishing) of a silicon wafer.

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. By increasing the true specific gravity of silica, the polishing rate can be improved when polishing an object to be polished (for example, a silicon wafer). From the viewpoint of reducing scratches generated on the surface (polishing surface) of the object to be polished, silica particles having a true specific gravity of 2.2 or less are preferable. 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 abrasive grains in the technology disclosed herein may be in the form of primary particles, or may be in the form of secondary particles in which a plurality of primary particles are aggregated. Further, abrasive grains in the form of primary particles and abrasive grains in the form of secondary particles may be mixed. In a preferred embodiment, at least some of the abrasive grains are in the form of secondary particles.

The average primary particle diameter of the abrasive grains is not particularly limited, but is preferably 5 nm or more, more preferably 10 nm or more from the viewpoint of polishing efficiency and the like. From the viewpoint of obtaining a higher polishing effect (for example, effects such as haze reduction and defect removal), the average primary particle size is preferably 15 nm or more, and more preferably 20 nm or more (for example, more than 20 nm). Further, from the viewpoint that a smoother surface can be easily obtained, the average primary particle diameter of the abrasive grains is preferably 100 nm or less, more preferably 50 nm or less, and further preferably 40 nm or less. From the viewpoint of easily obtaining a higher quality surface (for example, a surface with reduced defects such as LPD (Light Point Defect) and PID (Polishing Induced Defect)), the average primary particle diameter is typically 35 nm or less (typically Abrasive grains of less than 35 nm, preferably 32 nm or less, such as less than 30 nm may be used.

In addition, the average primary particle diameter of an abrasive grain can be calculated by the formula of average primary particle diameter (nm) = 2727 / S from the specific surface area S (m ² / g) measured by the BET method, for example. The measurement of the specific surface area of the abrasive grains can be performed using, for example, a surface area measuring device manufactured by Micromerex, Inc., trade name “FlowSorb II 2300”.

The average secondary particle diameter of the abrasive grains is not particularly limited, but is preferably 10 nm or more, more preferably 20 nm or more from the viewpoint of the polishing rate and the like. From the viewpoint of obtaining a higher polishing effect, the average secondary particle diameter is preferably 30 nm or more, more preferably 35 nm or more, and further preferably 40 nm or more (for example, more than 40 nm). Further, from the viewpoint of obtaining a surface with higher smoothness, the average secondary particle diameter of the abrasive grains is suitably 200 nm or less, preferably 150 nm or less, more preferably 100 nm or less. Abrasive grains having an average secondary particle diameter of less than 60 nm (more preferably less than 55 nm, for example, less than 50 nm) from the viewpoint of easily obtaining a higher quality surface (for example, a surface with reduced defects such as LPD and PID). May be used. The average secondary particle diameter of the abrasive grains is measured, for example, as a volume average particle diameter (volume-based arithmetic average diameter; Mv) by a dynamic light scattering method using a model “UPA-UT151” manufactured by Nikkiso Co., Ltd. Can do.

The average secondary particle diameter D2 of the abrasive grains is generally equal to or greater than the average primary particle diameter D1 of the abrasive grains (D2 / D1 ≧ 1), and typically larger than D1 (D2 / D1> 1). Although not particularly limited, from the viewpoint of polishing effect and surface smoothness after polishing, the D2 / D1 of the abrasive grains is usually suitably in the range of 1.2 to 3, 1.5 to A range of 2.5 is preferable, and a range of 1.7 to 2.3 (for example, 1.8 to 2.2) is more preferable.

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

Although not particularly limited, the average value of the major axis / minor axis ratio (average aspect ratio) of the primary particles of the abrasive grains is in principle 1.0 or more, preferably 1.05 or more, more preferably 1. 1 or more. Higher polishing rates can be achieved by increasing the average aspect ratio of the abrasive grains. 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, a predetermined number (for example, 200) of abrasive particles capable of recognizing the shape of independent particles using a scanning electron microscope (SEM) is used. Draw the smallest rectangle that circumscribes the image. 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.

(Basic compound)
In the technology disclosed herein, the polishing composition stock solution and the polishing composition diluted with the stock solution contain a basic compound. Here, the basic compound refers to a compound having a function of dissolving in water and increasing the pH of an aqueous solution. The basic compound functions to chemically polish the surface to be polished, and can contribute to the improvement of the polishing rate. In addition, the basic compound can be useful for improving the dispersion stability of the polishing composition (particularly the polishing composition stock solution).

As the basic compound, an organic or inorganic basic compound containing nitrogen, an alkali metal or alkaline earth metal hydroxide, various carbonates or hydrogencarbonates, and the like can be used. For example, alkali metal hydroxide, quaternary ammonium hydroxide or a salt thereof, ammonia, amine and the like can be mentioned. 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 the quaternary ammonium hydroxide or a salt thereof include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide 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. Such basic compounds can be used singly or in combination of two or more.

As basic compounds preferable from the viewpoint of improving the polishing rate, ammonia and ammonium salts (for example, quaternary ammonium salts such as tetramethylammonium hydroxide and tetraethylammonium hydroxide, ammonium hydrogencarbonate, ammonium carbonate, etc.), Examples include potassium hydroxide, sodium hydroxide, potassium bicarbonate, potassium carbonate, sodium bicarbonate and sodium carbonate. Of these, ammonia, ammonium salts such as tetramethylammonium hydroxide and tetraethylammonium hydroxide, potassium hydroxide and sodium hydroxide are preferred. More preferred are ammonia and ammonium salts such as tetramethylammonium hydroxide. A particularly preferred basic compound is ammonia.

(Water-soluble polymer)
The type of the water-soluble polymer contained in the polishing composition stock solution disclosed herein and the polishing composition diluted with the stock solution is not particularly limited, and is appropriately selected from water-soluble polymers known in the field of polishing compositions. You can choose. A water-soluble polymer can be used individually by 1 type or in combination of 2 or more types.

The water-soluble polymer may have at least one functional group selected from a cationic group, an anionic group and a nonionic group in the molecule. The water-soluble polymer may have, for example, a hydroxyl group, a carboxyl group, an acyloxy group, a sulfo group, a primary amide structure, a heterocyclic structure, a vinyl structure, or a polyoxyalkylene structure in the molecule. From the standpoint of reducing aggregates and improving detergency, a nonionic polymer can be preferably used as the water-soluble polymer.

Examples of water-soluble polymers include cellulose derivatives, starch derivatives, polymers containing oxyalkylene units, polymers containing nitrogen atoms, and polyvinyl alcohol. Of these, 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. Usually, 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 determined 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 (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. 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.

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

In the technique disclosed herein, the molecular weight of the water-soluble polymer is not particularly limited. The weight average molecular weight (Mw) of the water-soluble polymer can be, for example, 200 × 10 ⁴ or less, and is usually 150 × 10 ⁴ or less (typically 100 × 10 ⁴ or less). From the viewpoint of dispersion stability and the like, the Mw is preferably 90 × 10 ⁴ or less, more preferably 80 × 10 ⁴ or less, and further preferably 60 × 10 ⁴ or less. Further, from the viewpoint of improving the surface protection after polishing, usually, Mw is suitably 1 × 10 ⁴ or more, more preferably 10 × 10 ⁴ or more, and further preferably 20 × 10 ⁴ or more. The above Mw can be particularly preferably applied to a cellulose derivative (for example, HEC).

The relationship between the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the water-soluble polymer 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.

In addition, as Mw and Mn of the water-soluble polymer, values based on aqueous gel permeation chromatography (GPC) (aqueous, polyethylene oxide equivalent) can be adopted.

(water)
As the water constituting the polishing composition stock solution disclosed herein and the polishing composition diluted with the stock solution, ion-exchanged water (deionized water), pure water, ultrapure water, distilled water, etc. are preferably used. Can do. 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.

The polishing composition stock solution disclosed herein and the polishing composition diluted with the stock solution may further contain an organic solvent (lower alcohol, lower ketone, etc.) that can be uniformly mixed with water, if necessary. Good. Usually, 90% by volume or more of the solvent contained in the polishing composition is preferably water, and more preferably 95% by volume or more (typically 99 to 100% by volume) is water. In the present specification, the term “aqueous solvent” may be used as a general term including the solvent and water.

<Other ingredients>
The polishing composition stock solution disclosed here, and the polishing composition diluted with the stock solution are surfactants, chelating agents, organic acids, organic acid salts, inorganic acids as long as the effects of the present invention are not significantly hindered. Known additives that can be used in polishing compositions (typically, polishing compositions used in silicon wafer polishing processes), such as inorganic acid salts, preservatives, and fungicides, as necessary. It may be further contained.

A surfactant (typically a water-soluble organic compound having a molecular weight of less than 1 × 10 ⁴ ) that can be included as needed can contribute to an improvement in dispersion stability. As the surfactant, an anionic or nonionic surfactant can be preferably used. From the viewpoint of low foaming property and ease of pH adjustment, a nonionic surfactant is more preferable. For example, oxyalkylene polymers such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol; polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene alkylamine, polyoxyethylene fatty acid ester, polyoxyethylene glyceryl ether fatty acid Nonionic surfactants such as esters, polyoxyalkylene adducts such as polyoxyethylene sorbitan fatty acid esters; copolymers of plural types of oxyalkylene (diblock type, triblock type, random type, alternating type); It is done. Surfactant can be used individually by 1 type or in combination of 2 or more types.

The molecular weight of the surfactant is typically less than 1 × 10 ⁴ and is preferably 9500 or less from the viewpoints of filterability of the polishing composition, cleanability of the object to be polished, and the like. The molecular weight of the surfactant is typically 200 or more, preferably 250 or more, and more preferably 300 or more (for example, 500 or more) from the viewpoint of the haze reduction effect and the like. The molecular weight of the surfactant may be a weight average molecular weight (Mw) determined by GPC (aqueous, polyethylene glycol equivalent) or a molecular weight calculated from a chemical formula. In addition, the technique disclosed here can be implemented in the aspect using the polishing composition which does not contain surfactant as mentioned above substantially.

The chelating agent that can be contained as an optional component functions to suppress contamination of the object to be polished by metal impurities by forming and capturing metal ions and complex ions that can be contained in the polishing composition. Examples of chelating agents include aminocarboxylic acid chelating agents and organic phosphonic acid chelating agents. Examples of aminocarboxylic acid 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-based chelating agents are more preferable, and aminotri (methylenephosphonic acid), ethylenediaminetetrakis (methylenephosphonic acid), and diethylenetriaminepenta (methylenephosphonic acid) are particularly preferable. A chelating agent can be used individually by 1 type or in combination of 2 or more types. In addition, the technique disclosed here can be implemented in the aspect using the polishing composition which does not contain a chelating agent substantially.

Examples of organic acids include fatty acids such as formic acid, acetic acid and propionic acid, aromatic carboxylic acids such as benzoic acid and phthalic acid, citric acid, oxalic acid, tartaric acid, malic acid, maleic acid, fumaric acid, succinic acid, organic Examples include sulfonic acid and organic phosphonic acid. Examples of organic acid salts include alkali metal salts (sodium salts, potassium salts, etc.) and ammonium salts of organic acids. Examples of inorganic acids include sulfuric acid, nitric acid, hydrochloric acid, carbonic acid and the like. Examples of inorganic acid salts include alkali metal salts (sodium salts, potassium salts, etc.) and ammonium salts of inorganic acids. An organic acid and its salt, and an inorganic acid and its salt can be used individually by 1 type or in combination of 2 or more types. Examples of antiseptics and fungicides include isothiazoline compounds, paraoxybenzoates, phenoxyethanol and the like.

It is preferable that the polishing composition stock solution disclosed here and the polishing composition diluted with the stock solution are substantially free of an oxidizing agent. When an oxidizing agent is contained in the polishing composition, the composition is supplied to an object to be polished (for example, a silicon wafer), whereby the surface of the object to be polished is oxidized to produce 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.

<Method for producing polishing composition>
The polishing composition disclosed herein can be produced by diluting a polishing composition stock solution containing the above-mentioned abrasive grains, basic compound, water-soluble polymer and water, and optionally containing optional components. . In other words, the manufacturing method of the polishing composition disclosed here includes a step of diluting the polishing composition stock solution (dilution step).

(Polishing composition stock solution)
The polishing composition stock solution disclosed herein is defined as a product obtained by concentrating a polishing composition (polishing liquid) supplied to an object to be polished (ie, a concentrated liquid of the polishing liquid). The concentrated composition stock solution in such a concentrated form is advantageous from the viewpoints of convenience, cost reduction, etc. during production, distribution, storage, and the like.

In a preferred embodiment, the polishing composition stock solution used in the dilution step has the relation:
A = [CA × CP] / pHC
(In the above relational expression, CA is the content (% by weight) of abrasive grains in the polishing composition stock solution, CP is the content (% by weight) of the water-soluble polymer in the polishing composition stock solution, and pHC is polishing. The index A calculated | required from the pH value of the composition undiluted | stock solution for use is 0.8 or less. As a result, the polishing composition stock solution exhibits good dispersion stability. The index A obtained from the above relational expression is the stock solution that contributes to the dispersion of the product [CA × CP] of the abrasive content CA and the water-soluble polymer content CP that contributes to aggregation in the polishing composition stock solution. It is a value divided by pH (pHC). This index A is suitable as a criterion for determining the dispersion stability of components (typically abrasive grains and water-soluble polymers) in the stock solution. When the index A is not more than a predetermined value, the stock solution is well dispersed. Shows stability. The index A is more preferably 0.6 or less (for example, 0.45 or less, typically 0.25 or less) from the viewpoint of improving dispersion stability. The lower limit of the index A is greater than 0, and is usually 0.05 or more (for example, 0.1 or more) from the viewpoint of polishing performance or the like.

The content of abrasive grains in the polishing composition stock solution disclosed herein can typically be set within a range where the index A is a predetermined value or less. The upper limit of the content of abrasive grains in the stock solution can be, for example, 50% by weight or less. From the viewpoint of dispersion stability of the stock solution, filterability, etc., the content of abrasive grains is usually suitably 45% by weight or less (eg 40% by weight or less, typically 30% by weight or less), Preferably it is 25 weight% or less, More preferably, it is 20 weight% or less (for example, 15 weight% or less). The content of the abrasive grains in the stock solution is usually 0.5% by weight or more (for example, 1% by weight) from the viewpoints of the abrasive concentration of the polishing composition after dilution, convenience of production, distribution, storage and the like. As mentioned above, it is suitable that it is typically 3% by weight or more), preferably 5% by weight or more (for example, 9% by weight or more).

The content of the water-soluble polymer in the polishing composition stock solution disclosed herein can be typically set within a range in which the index A is a predetermined value or less, as in the case of the content of abrasive grains. . The upper limit of the content of the water-soluble polymer in the stock solution can be, for example, 5% by weight or less. From the viewpoint of dispersion stability of the stock solution, polishing rate, detergency, etc., the content of the water-soluble polymer should be 3% by weight or less (eg, 1% by weight or less, typically 0.75% by weight or less). preferable. The content of the water-soluble polymer in the stock solution is 0.001% by weight or more (for example, 0.01% by weight) from the viewpoints of the water-soluble polymer molar concentration in the diluted polishing composition, surface quality improvement (for example, haze reduction), and the like. % Or more), and preferably 0.1% by weight or more (typically 0.2% by weight or more).

The molar concentration of the water-soluble polymer in the polishing composition stock solution disclosed herein can typically be set so that the molar concentration of the water-soluble polymer in the polishing composition after dilution is a predetermined value or more. Specifically, the molar concentration of the water-soluble polymer in the polishing composition stock solution is higher than 7.0 × 10 ⁻⁸ mol / L. The molar concentration is 1.0 × 10 ⁻⁷ mol / L or more (for example, 1.0 × 10 ⁻⁶ mol / L or more, typically 3.0 × 10 ⁻⁶ mol / L or more). It is suitable, and preferably 4.3 × 10 ⁻⁶ mol / L or more (typically 1.0 × 10 ⁻⁵ mol / L or more). The upper limit of the molar concentration of the water-soluble polymer in the stock solution is usually 1.0 × 10 ⁻⁴ mol / L or less (for example, 5.0 × 10 ⁻⁵ mol) from the viewpoint of dispersion stability, polishing rate, detergency and the like. / L or less). In this specification, the molar concentration (mol / L) of the water-soluble polymer is the weight (g) of the water-soluble polymer contained in 1 liter of the polishing composition (including the stock solution and the diluted polishing solution). Is divided by the molecular weight (typically Mw) of the water-soluble polymer.

The content of the basic compound in the polishing composition stock solution disclosed herein is, for example, 0.1% by weight or more (typically) from the viewpoint of dispersion stability, improvement of the polishing rate by the polishing composition after dilution, and the like. Is preferably 0.3% by weight or more), preferably 0.5% by weight or more, more preferably 0.6% by weight or more, and even more preferably 0.8% by weight or more (eg, 1.0% by weight). % Or more, typically 1.2% by weight or more). For example, when diluting the stock solution at a high magnification and using it, the abrasive concentration after dilution is relatively low, and the processing force by the abrasive 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 stock solution. The upper limit of the content of the basic compound in the stock solution is suitably 5% by weight or less, preferably 3% by weight or less (eg, 2% by weight or less, typically from the viewpoint of storage stability, surface quality, etc. Specifically, it is 1.5% by weight or less). In the embodiment in which ammonia is used as the basic compound, the above content is particularly significant.

In a preferred embodiment, the polishing composition stock solution has the relation:
B = [CA × CP] / CB
(In the above relational expression, CA is the content (% by weight) of abrasive grains in the polishing composition stock solution, CP is the content (% by weight) of the water-soluble polymer in the polishing composition stock solution, and CB is polishing. Is the basic compound content (% by weight) in the composition stock solution.); The index B is suitably 6.5 or less (for example, 6.2 or less), more preferably 6.0 or less, and even more preferably 5.0 or less from the viewpoint of improving dispersion stability. Especially preferably, it is 4.5 or less (for example, 4.0 or less, typically 3.8 or less). The lower limit of the index B is larger than 0, and is usually 1.0 or more (typically 1.5 or more, for example, 2.5 or more) from the viewpoint of polishing performance or the like. The index B can be particularly preferably used as a criterion for determining the dispersion stability of a polishing composition stock solution when the basic compound is ammonia or an ammonium salt (typically ammonia).

In a preferred embodiment, the ratio (CA / CB) of the abrasive content CA (wt%) to the basic compound content CB (wt%) in the polishing composition stock solution is less than 25. Thereby, the dispersibility of the abrasive grains (for example, silica abrasive grains) tends to be improved, and the chemical polishing power of the polishing composition after dilution is strengthened. A polishing rate can be preferably realized. The ratio (CA / CB) is suitably 24 or less (for example, 20 or less), more preferably 15 or less, still more preferably 12 or less, and particularly preferably 10 or less (for example, 9 or less, Typically 8 or less). The lower limit of the ratio (CA / CB) is usually larger than 1 and about 3 or more (for example, 5 or more, typically 6 or more) from the viewpoint of performing well-balanced CMP polishing. . The value of the ratio (CA / CB) can be particularly preferably applied when the basic compound is ammonia or an ammonium salt (typically ammonia).

The pH of the polishing composition stock solution disclosed herein is usually suitably 8.0 or more (for example, 8.5 or more, typically 9.0 or more), preferably 9.0 or more. More preferably 9.5 or more, still more preferably 10.0 or more (typically 10.5 or more, for example 10.7 or more). When the pH is increased, the index A is decreased, and the dispersion stability of the stock solution tends to be easily obtained. Moreover, when pH becomes high, the pH of the polishing composition after dilution can also become high in conjunction. In that case, the polishing rate tends to improve. In other words, by increasing the pH of the stock solution, both the dispersion stability and the polishing rate can be improved. Furthermore, the high pH design as described above permits, for example, polishing in which the stock solution is highly concentrated and the abrasive concentration tends to be relatively low in an embodiment in which the stock solution is diluted at a high magnification. It can help to supplement the processing force by the liquid with chemical polishing. The upper limit of the pH of the stock solution is not particularly limited, but is preferably 12.0 or less (for example, 11.5 or less) and more preferably 11.0 or less from the viewpoint of surface quality and the like. From the viewpoint of better exerting the effect of applying the technology disclosed herein, when the basic compound is ammonia or ammonium salt (typically ammonia), the pH of the stock solution is set to 10.8. This is particularly meaningful. In this specification, the pH of the polishing composition stock solution (concentrated solution) and the polishing composition (polishing solution) is a pH meter (for example, a glass electrode type hydrogen ion concentration indicator (model number F-23 manufactured by Horiba, Ltd.)). )), Standard buffer (phthalate pH buffer pH: 4.01 (25 ° C.), neutral phosphate pH buffer pH: 6.86 (25 ° C.), carbonate pH buffer pH : 10.01 (25 ° C)), then calibrate three points, put the glass electrode in the concentrate or polishing liquid, and grasp the value by measuring the value after 2 minutes or more has stabilized Can do.

(Dilution)
In the production method disclosed herein, the polishing composition stock solution having the index A of a predetermined value or less is diluted. In a preferred embodiment, the dilution is specifically performed until the pH change is 0.15 or more. Here, the pH change is the difference between the pH of the stock solution before dilution and the pH of the polishing composition (typically polishing solution) after dilution. In the case of producing a polishing composition at a dilution that causes a pH change of a predetermined value or more as described above, by applying the technique disclosed herein, the dispersion stability is good in the case of a stock solution, and after dilution, A polishing composition capable of realizing good surface quality can be realized. Further, the change in pH due to dilution being not less than a predetermined value can be advantageous for realizing a good polishing rate. In the configuration in which the pH change is 0.3 or more (typically 0.35 or more, for example, 0.4 or more), the effect of the technique disclosed herein is better exhibited. Moreover, a large pH change means that the pH of the stock solution is higher in a polishing composition having a pH of 8 or higher. Such a high pH undiluted solution can contribute to the improvement of dispersion stability by increasing the electrostatic repulsion force of abrasive grains (for example, silica abrasive grains) before dilution. Further, after dilution, the pH is appropriately lowered depending on the degree of dilution, and a polishing composition suitable for maintaining and improving surface quality (for example, reducing haze) can be obtained. The upper limit of the pH change is suitably 0.6 or less (for example 0.5 or less) in consideration of the balance between the dispersion stability of the stock solution and the polishing performance of the diluted composition, 0.45 or less (for example, 0.4 or less).

In a preferred embodiment, the dilution step is a step of diluting the polishing composition stock solution 50 times or more on a volume basis. The stock solution diluted and used at such a high magnification tends to have a high concentration of the components contained therein, so that the components are likely to aggregate and it is difficult to obtain good dispersion stability. In such a configuration, typically, the stock solution can exhibit good dispersion stability by setting the index A to a predetermined value or less. According to the technique disclosed herein, even in a configuration using a stock solution that is diluted 60 times or more (for example, 80 times or more) on a volume basis, when the stock solution is used, the dispersion stability is good, and the diluted polishing composition is used. And good surface quality can be realized. By applying the technique disclosed herein, it is possible to achieve a desired effect even in a configuration in which the stock solution is diluted more than 100 times (for example, diluted by 110 times or more) on a volume basis. The upper limit of the dilution ratio is not particularly limited, but may be about 200 times or less (eg, 140 times or less, typically 120 times or less) on a volume basis.

The above dilution can be performed at a desired timing. Typically, the dilution can be performed by adding the above-mentioned aqueous solvent (typically water) to the stock solution and mixing. 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. Further, in a multi-drug type polishing composition, a part of the agent (stock solution) may be diluted and then mixed with another agent to prepare a polishing composition (polishing solution). After mixing these agents, the mixture (stock solution) may be diluted to prepare a polishing composition (polishing solution).

In the dilution step, dilution is preferably performed using a liquid that does not substantially contain a basic compound. By adopting such a dilution method, it is possible to preferably carry out dilution such that the pH change becomes a predetermined value or more. Here, the phrase “the liquid does not substantially contain a basic compound” means that the liquid does not contain a basic compound at least intentionally. Therefore, a liquid that inevitably contains a small amount (for example, 0.001% by weight or less, preferably 0.0001% by weight or less) of a basic compound is a liquid that does not substantially contain a basic compound. It can be included in the concept of Further, the pH of the liquid (typically an aqueous solvent) used in the dilution step is around 7 (for example, more than 6 and less than 8, typically 7 ± 0.5). As the liquid used for the dilution, it is preferable to use an aqueous solvent substantially composed of water (for example, an aqueous solvent in which 99.5 to 100% by volume is water) from the viewpoints of handleability and workability.

(Polishing composition)
In a preferred embodiment, the molar concentration of the water-soluble polymer in the diluted polishing composition is 7.0 × 10 ⁻⁸ mol / L or more. In other words, in the production method disclosed herein, the polishing composition is diluted so that the molar concentration of the water-soluble polymer is 7.0 × 10 ⁻⁸ mol / L or more. Thereby, good surface quality (typically a low haze surface) can be achieved. The molar concentration is 7.1 × 10 ⁻⁸ mol / L or more (for example, 7.5 × 10 ⁻⁸ mol / L or more, typically 9.0 × 10 ⁻⁸ mol / L or more). Appropriate, preferably 1.0 × 10 ⁻⁷ mol / L or more, more preferably 1.25 × 10 ⁻⁷ mol / L or more (eg 1.3 × 10 ⁻⁷ mol / L or more, typically 2.0 × 10 ⁻⁷ mol / L or more). The upper limit of the molar concentration is usually 1.0 × 10 ⁻⁴ mol / L or less (for example, 5.0 × 10 ⁻⁵ mol / L or less) from the viewpoint of dispersion stability, polishing rate, detergency, and the like. Is preferably 1.0 × 10 ⁻⁵ mol / L or less (for example, 1.0 × 10 ⁻⁶ mol / L or less).

The content of the water-soluble polymer in the polishing composition can typically be appropriately set within a range that satisfies the molar concentration. The content of the water-soluble polymer is 1 × 10 ⁻⁴ wt% or more (for example, 5 × 10 ⁻⁴ wt% or more) from the viewpoint of improving the water-soluble polymer molar concentration, improving the surface quality (typically haze reduction) It is suitable that it is 1 × 10 ⁻³ wt% or more (for example, 2 × 10 ⁻³ wt% or more). The upper limit of the content of the water-soluble polymer in the polishing composition can be, for example, 5% by weight or less. From the viewpoint of dispersion stability of the stock solution, polishing rate, detergency, etc., the content of the water-soluble polymer is 0.5% by weight or less (eg 0.2% by weight or less, typically 0.1% by weight or less). It is preferable that

In the technique disclosed herein, the content of abrasive grains in the polishing composition is typically 0.01% by weight or more, preferably 0.03% by weight or more, and preferably 0.06% by weight. % Or more (for example, 0.1% by weight or more) is more preferable. Higher polishing rates can be achieved by increasing the abrasive content. From the viewpoint of detergency, the content is suitably about 10% by weight or less (eg, 3% by weight or less), preferably less than 1% by weight, more preferably 0.8% by weight. And more preferably less than 0.6% by weight (eg less than 0.4% by weight, typically less than 0.2% by weight).

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 0.003% by weight or more). From the viewpoint of improving the rate, etc., it is preferably 0.005% by weight or more, more preferably 0.006% by weight or more, still more preferably 0.008% by weight or more (eg, 0.01% by weight or more, typically 0.8% or more. 012% by weight or more). Dispersion stability can also be improved by increasing the content of the basic compound. The upper limit of the content of the basic compound is suitably 1% by weight or less, and is preferably 0.1% by weight or less (eg 0.05% by weight or less, typically from the viewpoint of surface quality) Is 0.02% by weight or less).

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 further preferably 9.5 or more (for example, 10). 0.0 or more). When the pH of the polishing liquid increases, the polishing rate tends to improve. The upper limit value of the pH of the polishing liquid is not particularly limited, but 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. preferable. From the viewpoint of improving the surface quality (typically haze reduction), the pH is more preferably 10.8 or less (for example, 10.6 or less, typically 10.5 or less). The pH can be preferably applied to, for example, a polishing liquid used for polishing a silicon wafer (for example, a polishing liquid for final polishing).

Also, when a surfactant is used, the amount used is not particularly limited. Usually, from the viewpoint of detergency and the like, it is appropriate to use the surfactant in an amount of 20 parts by weight or less with respect to 100 parts by weight of the abrasive contained in the polishing composition, preferably 15 parts by weight or less, 10 parts by weight or less (for example, 6 parts by weight or less) is more preferable. From the viewpoint of better exerting the effect of using the surfactant, the amount of the surfactant to be used with respect to 100 parts by weight of the abrasive is suitably 0.001 part by weight or more, preferably 0.005 part by weight or more. 01 parts by weight or more (for example, 0.1 parts by weight or more) is more preferable. Alternatively, from the viewpoint of simplification of the composition and the like, the surfactant may not be substantially used.

The polishing composition produced as described above can be used as a polishing liquid supplied to the object to be polished. In addition, the manufacturing method disclosed here may include the process of preparing polishing composition stock solution before a dilution process. The preparation of the polishing composition stock solution can typically be the preparation or acquisition of the stock solution. The stock solution may be prepared by, for example, mixing each component contained in the polishing composition stock solution using a well-known mixing device such as a wing 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.

<Application>
The polishing composition in the technique disclosed herein can be applied to polishing a polishing object having various materials and shapes. The material of the polishing object is, for example, a metal or semimetal such as silicon, aluminum, nickel, tungsten, copper, tantalum, titanium, stainless steel, or an alloy thereof; glass such as quartz glass, aluminosilicate glass, glassy carbon, etc. A ceramic material such as alumina, silica, sapphire, silicon nitride, tantalum nitride, and titanium carbide; a compound semiconductor substrate material such as silicon carbide, gallium nitride, and gallium arsenide; a resin material such as polyimide resin; Of these, a polishing object composed of a plurality of materials may be used. Especially, it is suitable for grinding | polishing of the grinding | polishing target object provided with the surface which consists of silicon | silicone. The technique disclosed here is, for example, a polishing composition containing silica particles as abrasive grains (typically, a polishing composition containing only silica particles as abrasive grains), and the object to be polished is silicon. This is suitable as a method for producing a polishing composition. The shape of the object to be polished is not particularly limited. The polishing composition in the technique disclosed herein can be preferably applied to polishing a polishing object having a flat surface such as a plate shape or a polyhedron shape.

The polishing composition in the technique disclosed herein can be preferably used for final polishing of an object to be polished. Therefore, the matter disclosed by this specification includes a manufacturing method of a polished article (for example, a manufacturing method of a silicon wafer) including a final polishing step using the polishing composition. Note that final polishing refers to the final polishing step in the manufacturing process of the object (that is, a step in which no further polishing is performed after that step). The polishing composition in the technology disclosed herein also refers to a polishing step upstream of final polishing (a step between a rough polishing step and a final polishing step. Typically, the polishing composition includes at least a primary polishing step. Further, it may include a polishing process such as secondary, tertiary, etc.). For example, it may be used in a polishing process performed immediately before final polishing.

The polishing composition in the technique disclosed herein can be particularly preferably used for polishing a surface made of silicon (typically polishing a silicon wafer). For example, it is suitable as a polishing composition used for final polishing of a silicon wafer or a polishing process upstream thereof. For example, application to polishing (typically final polishing or polishing immediately before) of a silicon wafer prepared to have a surface roughness of 0.01 nm to 100 nm by an upstream process is effective. Application to final polishing is particularly preferable.

<Polishing>
Polishing of the object to be polished can be performed, for example, as follows. That is, any polishing composition disclosed herein is prepared. Next, the polishing composition is supplied to the object to be polished and polished by a conventional method. For example, when final polishing of a silicon wafer is performed, the silicon wafer that has undergone the lapping process and the primary polishing process is set in a general polishing apparatus, and the surface of the silicon wafer (surface to be polished) is passed through the polishing pad of the polishing apparatus. ) Is supplied with the polishing composition. Typically, while continuously supplying the polishing composition, a polishing pad is pressed against the surface of the silicon wafer to relatively move (for example, rotate) the two. The polishing of the object to be polished is completed through this polishing step. The polishing pad used in the polishing step is not particularly limited. For example, any of non-woven fabric type, suede type, those containing abrasive grains, those not containing abrasive grains, etc. may be used. The polishing step as described above may be a part of a manufacturing process of a polished object (for example, a substrate such as a silicon wafer). Therefore, according to this specification, a method for producing a polished article (preferably, a method for producing a silicon wafer) including the polishing step is provided.

<Washing>
The polished article after the polishing step is typically washed. This washing can be performed using an appropriate washing solution. The cleaning solution to be used is not particularly limited. For example, an SC-1 cleaning solution (ammonium hydroxide (NH ₄ OH), hydrogen peroxide (H ₂ O ₂ ), water (H ₂ O), etc. Hereinafter, cleaning with the SC-1 cleaning solution is referred to as “SC-1 cleaning”), SC-2 cleaning solution (mixed solution of HCl, H ₂ O ₂ and H ₂ O), etc. Can be used. The temperature of the cleaning liquid can be, for example, about room temperature to 90 ° C. From the viewpoint of improving the cleaning effect, a cleaning solution of about 50 ° C. to 85 ° C. can be preferably used.

The matters disclosed by this specification include the following.
(1) Including abrasive grains, basic compound, water-soluble polymer and water, relational formula:
A = [CA × CP] / pHC
(In the above relational expression, CA is the content (% by weight) of abrasive grains in the polishing composition stock solution, CP is the content (% by weight) of the water-soluble polymer in the polishing composition stock solution, and pHC is polishing. A polishing composition stock solution having an index A of 0.8 or less.
(2) The polishing composition stock solution according to (1) above, wherein the molar concentration of the water-soluble polymer is 4.3 × 10 ⁻⁶ mol / L or more.
(3) The polishing composition stock solution according to (1) or (2), wherein the polishing composition is used so that the pH change is 0.15 or more.
(4) The polishing composition stock solution according to any one of the above (1) to (3), which is used after being diluted 50 times or more on a volume basis.
(5) The polishing composition stock solution according to any one of (1) to (4), wherein the basic compound is ammonia and / or an ammonium salt.

(6) containing abrasive grains, basic compound, water-soluble polymer and water,
Relational expression:
B = [CA × CP] / CB
(In the above relational expression, CA is the content (% by weight) of abrasive grains in the polishing composition stock solution, CP is the content (% by weight) of the water-soluble polymer in the polishing composition stock solution, and CB is polishing. A basic composition content (% by weight) in the composition stock solution for polishing.) Polishing composition stock solution having an index B calculated from: 7.0 or less.
(7) The polishing composition stock solution according to (6) above, wherein the molar concentration of the water-soluble polymer is 4.3 × 10 ⁻⁶ mol / L or more.
(8) The polishing composition stock solution according to (6) or (7), wherein the polishing composition is used so that the pH change is 0.15 or more.
(9) The polishing composition stock solution according to any one of (6) to (8), wherein the polishing composition stock solution is used after being diluted 50 times or more on a volume basis.
(10) The polishing composition stock solution according to any one of (6) to (9), wherein the basic compound is ammonia and / or an ammonium salt.

(11) Abrasive grains, basic compound, water-soluble polymer and water are included, and the ratio (CA / CB) of abrasive grain content CA (wt%) to basic compound content CB (wt%) is less than 25 A polishing composition stock solution.
(12) Characteristic (A) The index A is 0.8 or less; and Characteristic (B) The index B is 7.0 or less; ) Polishing composition stock solution.
(13) The polishing composition stock solution according to (11) or (12) above, wherein the molar concentration of the water-soluble polymer is 4.3 × 10 ⁻⁶ mol / L or more.
(14) The polishing composition stock solution according to any one of (11) to (13), wherein the polishing composition is used by diluting so that the pH change is 0.15 or more.
(15) The polishing composition stock solution according to any one of the above (11) to (14), which is used after being diluted 50 times or more on a volume basis.
(16) The polishing composition stock solution according to any one of (11) to (15) above, wherein the basic compound is ammonia and / or an ammonium salt.

(17) A polishing composition stock solution used in a method for producing a polishing composition, wherein the molar concentration of the water-soluble polymer is 7.0 × 10 ⁻⁸ mol / L or more,
Including abrasive grains, basic compounds, water-soluble polymers and water,
Characteristic (A) The index A is 0.8 or less;
Characteristic (B) The index B is 7.0 or less; and Characteristic (C) The ratio (CA / CB) is less than 25;
A polishing composition stock solution that satisfies at least one of (eg, two, typically all).
(18) The polishing composition stock solution according to (17), wherein the polishing composition is produced by diluting the polishing composition stock solution until the pH change becomes 0.15 or more.
(19) The polishing composition stock solution according to (17) or (18), wherein the polishing composition is produced by diluting the polishing composition stock solution 50 times or more on a volume basis.

(20) A method for producing a polishing composition, comprising the step of diluting a polishing composition stock solution containing abrasive grains, a basic compound, a water-soluble polymer and water 50 times or more on a volume basis,
The polishing composition stock solution has a relational formula:
A = [CA × CP] / pHC
(In the above relational expression, CA is the content (% by weight) of abrasive grains in the polishing composition stock solution, CP is the content (% by weight) of the water-soluble polymer in the polishing composition stock solution, and pHC is polishing. The index A obtained from the above is a pH value of 0.8 or less, and the molar concentration of the water-soluble polymer in the polishing composition after dilution is 7.0 × 10 ⁻⁸ mol. The manufacturing method of the polishing composition which is more than / L.

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.

<Preparation of polishing composition>
(Example 1)
Colloidal silica as abrasive grains, ammonia (NH ₃ ) as a basic compound, HEC (Mw 25 × 10 ⁴ ) as a water-soluble polymer, and pure water are mixed, and the polishing composition stock solution according to this example Was prepared. Abrasive grains, ammonia, and HEC are used in an amount of 9.2% in the stock solution, 1.27% in ammonia, and 0.49% in HEC (molar concentration 2.0). × 10 ⁻⁵ mol / L). The pH of the obtained stock solution was 10.82. As the abrasive grains, colloidal silica having an average primary particle diameter of 35 nm and an average secondary particle diameter of 66 nm was used. The average primary particle size is measured using a surface area measuring device manufactured by Micromerex, Inc., trade name “FlowSorb II 2300”. The average secondary particle diameter is a volume average secondary particle diameter measured using a model “UPA-UT151” manufactured by Nikkiso Co., Ltd. A polishing composition according to this example was obtained by adding pure water to the stock solution and diluting the stock solution 80 times on a volume basis. The composition of the polishing composition stock solution of Example 1 is shown in Table 1. The composition of the polishing composition after dilution is shown in Table 2. Table 1 also shows the value of the index A obtained from the above relational expression. Table 2 also shows the dilution ratio (volume basis) and pH change (difference between the pH of the polishing composition stock solution and the pH of the polishing composition after dilution).

(Examples 2 to 7, Comparative Examples 1 to 3)
The polishing composition stock solution abrasive grain concentration, basic compound species and concentration, water-soluble polymer species (Mw) and concentration were changed to the contents shown in Table 1, and the dilution factor was changed to the magnification shown in Table 2 In the same manner as in Example 1, polishing compositions according to each example were prepared. Table 1 also shows the pH and index A of the stock solution according to each example. The composition of the polishing composition after dilution is shown in Table 2.

<Stability test>
A polishing composition stock solution according to each example was prepared (prepared) and allowed to stand at 25 ° C. for storage. The presence or absence of sediment in the stock solution after 5 days from the start of storage was evaluated visually according to the following two criteria. That is, when there was no sediment, it was evaluated as “A”, and when sediment was observed, it was evaluated as “C”. The results are shown in Table 2.

<Polishing of silicon wafer>
The polishing compositions according to Examples 1 to 7 and Comparative Example 3 were directly used as a polishing liquid, and the surface of the silicon wafer was polished under the following conditions. A silicon wafer having a diameter of 300 mm, a conductivity type of P type, a crystal orientation of <100>, and a resistivity of 0.1 Ω · cm to less than 100 Ω · cm is a polishing slurry (manufactured by Fujimi Incorporated, product The surface roughness was adjusted to 0.1 nm to 10 nm by performing preliminary polishing using the name “GLANZOX2100”). In addition, about the polishing composition which concerns on Comparative Examples 1 and 2, the said grinding | polishing was not implemented because of stability stability of a stock solution.

[Polishing conditions]
Polishing machine: Single wafer polishing machine manufactured by Okamoto Machine Tool Manufacturing Co., Ltd. Model “PNX-332B”
Polishing table: Final polishing 1st stage and 2nd stage after preliminary polishing were carried out using 2 tables at the back stage among the 3 tables of the polishing machine. (The following conditions are the same for each table.)
Polishing load: 15 kPa
Plate rotation speed: 30 rpm
Head rotation speed: 30rpm
Polishing time: 2 minutes Polishing liquid temperature: 20 ° C
Polishing liquid supply rate: 2.0 l / min

<Washing>
The polished silicon wafer was cleaned using a cleaning solution of ammonia (29%): H 2 O 2 (31%): deionized water (DIW) = 1: 3: 30 (volume ratio) (SC-1 cleaning). More specifically, two cleaning tanks equipped with an ultrasonic oscillator with a frequency of 950 kHz are prepared, the cleaning liquid is accommodated in each of the first and second cleaning tanks and held at 60 ° C., and after polishing. The silicon wafer was immersed in the first cleaning tank for 6 minutes, then passed through an ultrapure water and ultrasonic rinsing tank, and then in the second cleaning tank for 6 minutes, each with the ultrasonic oscillator being operated.

<Haze measurement>
Using a wafer inspection device manufactured by KLA-Tencor Corporation, trade name “Surfscan SP2”, haze (ppm) was measured in the DWO mode on the cleaned silicon wafer surface, and the following three levels were evaluated. The obtained results are shown in the “Haze” column of Table 2.
A: 0.08 ppm or less B: More than 0.08 ppm and 0.09 ppm or less C: Greater than 0.09 ppm

As shown in Table 1 and Table 2, the stock solutions of Examples 1 to 7 having an index A of 0.8 or less showed good dispersion stability in the stability test. On the other hand, in the stock solutions of Comparative Examples 1 and 2 in which the index A exceeded 0.8, sediment was observed in the stability test, and a stable dispersion state could not be maintained. Further, it is a polishing liquid (polishing composition) obtained by diluting a stock solution having an index A of 0.8 or less so that the pH change is 0.15 or more, and the molar concentration of the water-soluble polymer is 7.0 × 10. ^In Examples 1 to 7, which were ^-8 mol / L or more, the haze reduction effect was superior to Comparative Example 3 in which the molar concentration of the water-soluble polymer was less than 7.0 × 10 ^-8 mol / L. It was. From these results, the molar concentration (mol / L) of the water-soluble polymer in the polishing composition after dilution was 7.0 × 10 ⁻ using a polishing composition stock solution having an index A of 0.8 or more. By setting it to ⁸ or more, it can be seen that dispersion stability is good in the case of a stock solution, and even when diluted at a high magnification, good surface quality can be realized after dilution.

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 (9)

1. A method for producing a polishing composition comprising:
   Diluting a polishing composition stock solution containing abrasive grains, a basic compound, a water-soluble polymer and water so that the pH change is 0.15 or more,
   The polishing composition stock solution has a relational formula:
   A = [CA × CP] / pHC
   And the molar concentration of the water-soluble polymer in the polishing composition after dilution is 7.0 × 10 ⁻⁸ mol / L or more. Is the content (% by weight) of abrasive grains in the polishing composition stock solution, CP is the content (% by weight) of the water-soluble polymer in the polishing composition stock solution, and pHC is the pH value of the polishing composition stock solution. The manufacturing method of polishing composition which is.
2. The manufacturing method according to claim 1, wherein the dilution step is performed using a liquid that does not substantially contain a basic compound.
3. The manufacturing method according to claim 1 or 2, wherein the dilution step is a step of diluting the polishing composition stock solution so that the pH change becomes 0.3 or more.
4. The production method according to any one of claims 1 to 3, wherein the dilution step is a step of diluting the polishing composition stock solution 50 times or more on a volume basis.
5. The production method according to any one of claims 1 to 4, wherein the diluted polishing composition has a pH of 8 to 12.
6. The production method according to any one of claims 1 to 5, wherein silica abrasive is used as the abrasive.
7. The production method according to any one of claims 1 to 6, wherein the water-soluble polymer has a weight average molecular weight of 90 × 10 ⁴ or less.
8. The manufacturing method according to any one of claims 1 to 6, wherein the polishing composition is used for polishing a silicon wafer.
9. A polishing composition stock solution used by diluting so that the pH change is 0.15 or more, comprising abrasive grains, a basic compound, a water-soluble polymer and water, and a relational formula:
   A = [CA × CP] / pHC
   The index A obtained from the formula is 0.8 or less, the molar concentration of the water-soluble polymer is 4.3 × 10 ⁻⁶ mol / L or more, and in the above relational formula, CA is the abrasive in the polishing composition stock solution. Polishing composition stock solution, which is the content (% by weight) of particles, CP is the content (% by weight) of the water-soluble polymer in the polishing composition stock solution, and pHC is the pH value of the polishing composition stock solution .