JP6387250B2 - Polishing composition manufacturing kit and use thereof - Google Patents

Description

  The present invention relates to a polishing composition manufacturing kit, a polishing composition, and a method for manufacturing the same.

  Conventionally, precision polishing using a polishing composition has been performed on the surface of materials such as metals, metalloids, nonmetals, and oxides thereof. For example, the surface of a silicon wafer used as a component of a semiconductor device or the like 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). Patent document 1 is mentioned as a technical document regarding polishing composition.

Japanese Patent Laid-Open No. 11-302634

In Patent Document 1, a polishing composition containing colloidal silica as abrasive grains is prepared as a buffer solution with a combination of a weak acid and a strong base, a strong acid and a weak base, or a combination of a weak acid and a weak base. It is described that a polishing composition having a high speed can be formed. Specifically, a polishing composition using a buffering action by a combination of tetramethylammonium hydroxide and potassium bicarbonate (KHCO ₃ ) is disclosed. However, when the polishing composition having such a composition is circulated and used repeatedly (recycled), particularly during preliminary polishing, the pH of the composition decreases with recycling, resulting in performance deterioration such as a decrease in polishing rate. It was known to occur. Further, the polishing composition having such a composition tends to be insufficient in storage stability. For example, when the polishing composition (concentrated liquid) in a concentrated form is stored for a long period of time compared to the polishing liquid (working slurry) used for polishing the object to be polished, the silica particles can be agglomerated to a level that can be visually confirmed. It sometimes progressed.

  As a technique for avoiding the storage stability problem, it is conceivable to prepare a polishing liquid by mixing the constituents of the polishing composition immediately before its use. However, according to the study by the present inventors, the polishing liquid obtained by mixing the constituents of the polishing composition described in Patent Document 1 immediately before its use is a concentrated liquid prepared by mixing in advance. The change in pH tended to be larger than that of the polishing liquid obtained by dilution.

  Therefore, an object of the present invention is to provide a polishing composition manufacturing kit that can manufacture a polishing composition having high pH maintainability and is excellent in storage stability. Another related object is to provide a method for producing a polishing composition using such a polishing composition production kit and a polishing composition produced by the method.

  According to this specification, a polishing composition production kit for producing a polishing composition comprising silica particles as abrasive grains, a strong base and a weak acid salt is provided. The polishing composition manufacturing kit (hereinafter sometimes simply referred to as “kit”) includes a plurality of agents stored separately from each other. In the above kit, when a mixed solution is prepared by combining these plural agents, the initial pH of the mixed solution is 11.8 or less (typically 8.0 or more and 11.8 or less). It is configured. Such a polishing composition production kit can have good storage stability because the constituents of the polishing composition are divided into a plurality of agents. Further, by configuring the plurality of agents so that the initial pH of the mixed solution is 11.8 or less, the polishing composition produced using this kit exhibits good pH maintainability. obtain.

  According to the present invention, there is also provided a kit for producing a polishing composition comprising silica particles as abrasive grains, a strong base and a weak acid salt, wherein the polishing composition comprises the agent A and the agent B as the plurality of agents. A product manufacturing kit is provided. The A agent and the B agent are stored separately from each other.

In a preferred embodiment, the agent A contains silica particles and a strong base. In the agent A, the relationship between the content Wb _A [wt%] of the strong base and the content Ws _A [wt%] of the silica particles preferably satisfies the following formula (A).
0.25 ≦ (Wb _A / Ws _A ) ≦ 1.00 (A)
According to the agent A satisfying the above formula (A), a polishing composition production kit that provides a polishing composition with improved one or both of pH maintainability and polishing rate can be realized.

In a preferred embodiment, the agent B contains a weak acid salt and typically further contains a strong base. In this agent _B , the relationship between the strong base concentration Mb _B [mol / L] and the weak acid salt concentration Ma _B [mol / L] preferably satisfies the following formula (B).
0 <(Mb _B / Ma _B ) ≦ 1.00 (B)
According to the agent B satisfying the above formula (B), a polishing composition production kit that provides a polishing composition with improved one or both of pH maintainability and polishing rate can be realized.

  In a preferred embodiment of the technology disclosed herein, the molar amount of the strong base contained in the agent A is 30% or more and 95% or less of the molar amount of all strong bases contained in the polishing composition manufacturing kit. It is. Such a kit can provide a polishing composition with improved one or both of pH maintenance and polishing rate.

  As the weak acid salt in the technique disclosed herein, a weak acid salt having at least one of acid dissociation constant (pKa) values in the range of 8.0 to 11.8 can be preferably used. By using such a weak acid salt, a kit in which the initial pH of the mixed solution is 8.0 or more and 11.8 or less can be suitably realized.

  As the weak acid salt, for example, at least one selected from the group consisting of carbonate, hydrogen carbonate, borate, phosphate, and phenol salt can be preferably used. By using such a weak acid salt, the effects of the kit disclosed herein can be suitably exhibited.

  As the strong base, at least one selected from the group consisting of alkali metal hydroxide, quaternary ammonium hydroxide, alkylamine, quaternary phosphonium hydroxide and ammonia can be preferably used. By using such a strong base, the effects of the kit disclosed herein can be suitably exhibited.

  According to this specification, the polishing composition manufacturing method characterized by using any of the kits disclosed herein is also provided. The manufacturing method typically includes mixing a plurality of agents included in the kit.

  The polishing composition production method disclosed herein can be preferably carried out using a kit containing the agent A and the agent B. In that case, the manufacturing method includes preparing the second composition by diluting the agent B with water, adding the first composition containing the agent A to the second composition, and mixing them. It can preferably be implemented in an embodiment including By this, the polishing composition which shows a more favorable characteristic can be manufactured.

  According to this specification, polishing composition manufactured using any kit indicated here is also provided. The polishing composition can be excellent in pH maintainability. In the production of such a polishing composition, any of the polishing composition production methods disclosed herein can be preferably employed.

It is a graph which shows the relationship between the distance from the outer periphery end of the silicon wafer after grinding | polishing, and surface shape displacement amount.

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

  According to this specification, a polishing composition production kit for producing a polishing composition containing at least silica particles as abrasive grains, a strong base and a weak acid salt is provided. Below, the structural component of the said polishing composition is demonstrated first, and then the polishing composition manufacturing kit which contains those structural components divided into two or more agents is demonstrated.

<Abrasive>
The technique disclosed herein can be preferably applied to a polishing composition using silica particles as abrasive grains and a kit for producing the composition. In the polishing composition used for polishing a silicon wafer, it is particularly meaningful to use silica particles as abrasive grains. The reason is that if silica particles consisting of the same elements and oxygen atoms as the object to be polished (silicon wafer) are used as abrasive grains, no metal or metalloid residue different from silicon is generated after polishing, and the silicon wafer surface This is because there is no possibility of contamination or deterioration of electrical characteristics as a silicon wafer due to diffusion of a metal or metalloid different from silicon into the object to be polished. As one form of a kit that is preferable from such a viewpoint, a kit containing only silica particles as an abrasive is exemplified. 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. From the viewpoint that scratches hardly occur on the surface of the object to be polished, preferred silica particles include colloidal silica and fumed silica. Of these, colloidal silica is preferred. For example, colloidal silica can be preferably used as abrasive grains of a kit for producing a polishing composition used for preliminary polishing or final polishing of a silicon wafer.

  The true specific gravity of the 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, a high polishing rate (amount for removing the surface of the object to be polished per unit time) can be easily obtained. In addition, the effect of reducing the surface roughness or level difference of the polishing object tends to increase. From these viewpoints, 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 measured value by a liquid substitution method using ethanol as a substitution liquid can be adopted.

  The abrasive grains 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 10 nm or more, more preferably 20 nm or more from the viewpoint of polishing efficiency and the like. From the viewpoint of obtaining a higher polishing effect, the average primary particle size is preferably 25 nm or more, and more preferably 30 nm or more. Abrasive grains having an average primary particle diameter of 40 nm or more may be used, and further, abrasive grains of 50 nm or more may be used. Further, from the viewpoint of storage stability (for example, dispersion stability), the average primary particle diameter of the abrasive grains is preferably 100 nm or less, more preferably 80 nm or less, still more preferably 70 nm or less, for example 60 nm or less.

In the technology disclosed herein, the average primary particle diameter of the abrasive grains is, for example, from the specific surface area S (m ² / g) measured by the BET method, average primary particle diameter (nm) = 2727 / S. It can be calculated by an equation. The measurement of the specific surface area of the abrasive grains can be performed using, for example, a surface area measuring device manufactured by Micromeritex Co., Ltd., trade name “Flow Sorb II 2300”.

  The average secondary particle diameter of the abrasive grains is not particularly limited, but is preferably 15 nm or more, and more preferably 25 nm or more, from the viewpoint of polishing rate and the like. From the viewpoint of obtaining a higher polishing effect, the average secondary particle size is preferably 40 nm or more, and more preferably 50 nm or more. Further, from the viewpoint of storage stability (for example, dispersion stability), 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. The average secondary particle diameter of the abrasive grains can be measured, for example, by a dynamic light scattering method using a model “UPA-UT151” manufactured by Nikkiso Co., Ltd.

  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 (average aspect ratio) of the major axis / minor axis ratio of the primary particles of the abrasive grains is 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.

The abrasive grain content in the polishing composition disclosed herein is not particularly limited.
As will be described later, in the case of a polishing composition (typically a slurry-like polishing liquid, sometimes referred to as a working slurry or a polishing slurry) used for polishing a polishing object as it is as a polishing liquid. The content of the abrasive grains is typically 0.05% by weight or more, preferably 0.1% by weight or more, and more preferably 0.2% by weight or more. Higher polishing rates can be achieved by increasing the abrasive content. The content of the abrasive grains may be 0.3% by weight or more, and may further be 0.5% by weight or more. From the viewpoint of dispersion stability and the like, the content is usually suitably 10% by weight or less, preferably 7% by weight or less, more preferably 5% by weight or less, and further preferably 3% by weight or less. 1% by weight or less.
In the case of a polishing composition (that is, a concentrated liquid) that is diluted and used for polishing, the content of abrasive grains can be, for example, 50% by weight or less. From the viewpoints of dispersion stability and filterability, the content of abrasive grains is usually preferably 45% by weight or less, more preferably 40% by weight or less. In a preferred embodiment, the abrasive content may be 30% by weight or less, or 20% by weight or less (eg, 15% by weight or less). Further, from the viewpoint of taking advantage of the concentrated solution, the content of the abrasive grains can be, for example, 0.5% by weight or more, preferably 1% by weight or more, more preferably 3% by weight or more (for example, 5% by weight or more).

<Strong base>
As the strong base, a base capable of exhibiting a desired buffering action in combination with a weak acid salt can be appropriately selected from various bases known to be usable in polishing using silica particles. A strong base can be used individually by 1 type or in combination of 2 or more types. Suitable examples include alkali metal hydroxides, quaternary ammonium hydroxides, quaternary phosphonium hydroxides, amines (preferably water-soluble amines) and ammonia. Specific examples of the alkali metal hydroxide include sodium hydroxide, potassium hydroxide, lithium hydroxide and the like. Specific examples of the quaternary ammonium hydroxide include tetramethylammonium hydroxide, tetraethylammonium hydroxide, and tetrabutylammonium hydroxide. Specific examples of the quaternary phosphonium hydroxide include tetramethylphosphonium hydroxide and tetraethylphosphonium hydroxide. Specific examples of amines include methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, ethylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, anhydrous piperazine, piperazine hexahydrate, 1- (2-aminoethyl) Examples include piperazine, N-methylpiperazine, guanidine, azoles such as imidazole and triazole.

  As the strong base in the technology disclosed herein, at least one selected from the group consisting of alkali metal hydroxides, quaternary ammonium hydroxides, alkylamines, quaternary phosphonium hydroxides and ammonia is preferably employed. be able to. Among these, a preferred strong base includes quaternary ammonium hydroxides such as tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide, and tetrabutylammonium hydroxide. TMAH is particularly preferred.

The content of the strong base in the polishing composition disclosed herein is not particularly limited, and can be set so that the pH falls within an appropriate range.
For example, in the case of a polishing composition used as a polishing liquid as it is, the molar amount of the strong base contained per liter (L) of the polishing composition is usually suitably 0.0001 mol or more. From the viewpoint of polishing rate, it is preferably 0.001 mol or more, more preferably 0.005 mol or more. From the viewpoint of preventing dissolution of silica particles due to a temporary increase in pH or the like, the molar amount of the strong base contained in the polishing composition is usually suitably 1 mol / L or less, 0.5 mol / L L or less is preferable.
In the case of a polishing composition (ie, concentrated solution) that is diluted and used as a polishing liquid, the molar amount of the strong base can be, for example, 0.001 to 10 mol / L, and 0.01 to 5 mol. / L is preferable.
In addition, as a strong base in this specification, the compound which can dissociate substantially completely in aqueous solution or polishing liquid can be employ | adopted preferably. The type and amount of strong base are typically selected so that the strong base can be substantially completely dissociated in an aqueous solution or polishing liquid.

<Weak acid salt>
As the weak acid salt in the technique disclosed herein, one that can be used for polishing using silica particles and can exhibit a desired buffering action in combination with a strong base can be appropriately selected. The weak acid salts can be used alone or in combination of two or more.
For example, carbonate ions, hydrogen carbonate ions, borate ions, phosphate ions, silicate ions, phenol ions, monocarboxylate ions (eg acetate ions), dicarboxylate ions (eg oxalate ions) , Maleate ion) and tricarboxylate ion (for example, citrate ion). Examples of the cation component constituting the salt include alkali metal ions such as potassium ion and sodium ion; alkaline earth metal ions such as calcium ion and magnesium ion; transition metal ions such as manganese ion, cobalt ion and zinc ion. An ammonium ion such as a tetraalkylammonium ion; a phosphonium ion such as a tetraalkylphosphonium ion; and the like. Specific examples of weak acid salts include sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium orthosilicate, potassium orthosilicate, sodium acetate, potassium acetate, sodium propionate, potassium propionate, calcium carbonate, calcium bicarbonate , Calcium acetate, calcium propionate, magnesium acetate, magnesium propionate, zinc propionate, manganese acetate, cobalt acetate and the like.

  From the viewpoint of obtaining a polishing composition having a good buffering action in a pH range suitable for polishing using silica particles (for example, polishing of a silicon wafer), at least one of the acid dissociation constant (pKa) values is 8.0 to 8.0. Preference is given to weak acid salts in the range of 11.8 (eg 8.0 to 11.5). Suitable examples include carbonates, bicarbonates, borates, phosphates, silicates and phenol salts. Especially, the weak acid salt whose anion component is a carbonate ion or hydrogencarbonate ion is preferable. Moreover, as a cation component, alkali metal ions, such as potassium and sodium, are suitable. Particularly preferred weak acid salts include sodium carbonate, potassium carbonate, sodium bicarbonate and potassium bicarbonate. Of these, potassium carbonate is preferred. As the value of pKa, the value of the acid dissociation constant at 25 ° C. described in known materials can be adopted.

  The content (concentration) of the weak acid salt in the polishing composition disclosed herein is not particularly limited. The content of the weak acid salt can be set so that the effect of improving the pH maintenance property is appropriately exhibited in consideration of the content of the strong base that exhibits a buffering action in relation to the weak acid salt. .

  In a preferred embodiment, the content of the weak acid salt (preferably alkali metal carbonate) contained per liter (L) of the polishing composition is 0.0001 from the viewpoint of pH maintenance properties of the polishing composition. It is appropriate that the amount be at least mol, more preferably at least 0.0002 mol, and even more preferably at least 0.0003 mol. Further, from the viewpoint of the dispersion stability of the polishing composition, the content of the weak acid salt contained per liter of the polishing composition is usually 1.0 mol or less. In the polishing composition used as a polishing liquid as it is, the content of the weak acid salt contained in 1 liter of the composition is preferably 0.1 mol or less, preferably 0.05 mol or less, more preferably 0.02 mol or less.

Although it does not specifically limit, when quaternary ammonium hydroxide (for example, TMAH) is used as a strong base and an alkali metal carbonate (for example, potassium carbonate) is used as a weak acid salt, the alkali contained in the polishing composition The ratio (m _T / m _C ) of the molar amount m _T of the quaternary ammonium hydroxide to the molar amount m _C of the metal carbonate can be set to 0.5 to 5, for example. Are _usually suitable to be 1 to 3 _(m T / m _C), preferably to 1.3 to 2.7, 1.3-2.3 (e.g., 1.7 to 2. 3) is more preferable. Thereby, a buffer effect is exhibited effectively and the effect which improves pH maintenance property can be realized suitably.

<Water>
The polishing composition disclosed herein typically contains water. As water, ion exchange water (deionized water), pure water, ultrapure water, distilled water and the like can be preferably used. The water to be used preferably has, for example, a total content of transition metal ions of 100 ppb or less in order to avoid as much as possible the action of other components contained in the polishing composition. For example, the purity of water can be increased by operations such as removal of impurity ions with an ion exchange resin, removal of foreign matter with a filter, distillation, and the like.
The polishing composition disclosed herein may further contain an organic solvent (lower alcohol, lower ketone, etc.) that can be uniformly mixed with water, if necessary. Usually, 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 (typically 99-100 volume%) is water.

<Other ingredients>
The polishing composition disclosed herein is a polishing composition (typically, a water-soluble polymer, a chelating agent, an antiseptic, an antifungal agent, etc.) as long as the effects of the present invention are not significantly hindered. A known additive that can be used in a polishing composition used in a polishing step of a silicon wafer may be further contained as necessary. The technique disclosed herein may also be carried out in such a manner that the polishing composition does not substantially contain a water-soluble polymer or a chelating agent.

By including a water-soluble polymer in the polishing composition, effects such as reduction in roll-off (end surface sag) of the object to be polished after polishing can be realized. Examples of the water-soluble polymer include cellulose derivatives, starch derivatives, polymers containing oxyalkylene units, polymers containing nitrogen atoms, vinyl alcohol polymers, and the like. Specific examples include hydroxyethyl cellulose, pullulan, random copolymer or block copolymer of ethylene oxide and propylene oxide, polyvinyl alcohol, polyisoprene sulfonic acid, polyvinyl sulfonic acid, polyallyl sulfonic acid, polyisoamylene sulfonic acid. Polystyrene sulfonate, polyacrylate, polyvinyl acetate, polyethylene glycol, polyvinyl pyrrolidone, polyacryloylmorpholine, polyacrylamide and the like. A water-soluble polymer can be used singly or in combination of two or more.
In the present specification, the term “copolymer” refers to various copolymers such as a random copolymer, an alternating copolymer, a block copolymer, and a graft copolymer unless otherwise specified. is there.

The water-soluble polymer will be described in more detail.
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.
Specific examples of starch derivatives include pullulan, pregelatinized starch, cyclodextrin and the like. Of these, pullulan is preferred.

  Examples of polymers containing oxyalkylene units include polyethylene oxide (PEO), block copolymers of ethylene oxide (EO) and propylene oxide (PO), random copolymers, and blocks of EO and butylene oxide (BO). A copolymer, a random copolymer, etc. are mentioned. Among these, a block copolymer or a random copolymer of EO and PO is preferable. A preferred example of a block copolymer of EO and PO is a PEO-PPO-PEO type triblock copolymer.

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 (pendant group) can be used.
Examples of the polymer containing a nitrogen atom in the main chain include homopolymers and copolymers of N-acylalkylenimine monomers such as N-acetylethyleneimine and N-propionylethyleneimine.

  Examples of polymers having a nitrogen atom in the pendant group include polymers containing N-vinyl type monomer units such as N-vinyl lactam and N-vinyl chain amide, and N- (meth) acryloyl type monomer units. Examples thereof include polymers. Here, “(meth) acryloyl” means acryloyl and methacryloyl comprehensively.

Specific examples of N-vinyl lactam include N-vinyl pyrrolidone (VP), N-vinyl piperidone, N-vinyl morpholinone, N-vinyl caprolactam (VC), N-vinyl-1,3-oxazin-2-one, N-vinyl-3,5-morpholinedione and the like can be mentioned. Specific examples of the N-vinyl chain amide include N-vinylacetamide, N-vinylpropionic acid amide, N-vinylbutyric acid amide and the like. Specific examples of the polymer containing monomer units of the N-vinyl lactam type include polyvinyl pyrrolidone, polyvinyl caprolactam, random copolymers of VP and VC, one or both of VP and VC, and other vinyl monomers (for example, acrylic type). Monomers, vinyl ester monomers, etc.), block copolymers and graft copolymers containing polymer segments containing one or both of VP and VC (for example, graft copolymer obtained by grafting polyvinylpyrrolidone to polyvinyl alcohol) Polymer) and the like.
A preferred example of the polymer containing an N-vinyl type monomer unit is a vinylpyrrolidone-based polymer. Here, the vinylpyrrolidone-based polymer means a VP homopolymer and a VP copolymer (for example, a copolymer having a VP copolymerization ratio of more than 50% by weight). In the vinylpyrrolidone-based polymer, the ratio of the number of moles of VP units to the number of moles of all repeating units is usually 50% or more, and 80% or more (for example, 90% or more, typically 95% or more). Is appropriate. All repeating units of the water-soluble polymer may be substantially composed of VP units. Here, “substantially” typically means that 98% or more of all repeating units are VP units.

  Examples of polymers containing N- (meth) acryloyl type monomer units include homopolymers and copolymers of N- (meth) acryloyl type monomers (typically copolymers of N- (meth) acryloyl type monomers). A copolymer having a polymerization ratio of more than 50% by weight). Examples of the N- (meth) acryloyl type monomer include a chain amide having an N- (meth) acryloyl group and a cyclic amide having an N- (meth) acryloyl group.

  Examples of chain amides having an N- (meth) acryloyl group include (meth) acrylamide; N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-propyl (meth) acrylamide, N-isopropyl ( N-monoalkyl (meth) acrylamides such as meth) acrylamide and Nn-butyl (meth) acrylamide; N- (2-hydroxyethyl) (meth) acrylamide, N- (1,1-dimethyl-2-hydroxyethyl) ) (Meth) acrylamide, N- (1-ethyl-hydroxyethyl) (meth) acrylamide, N- (2-chloroethyl) (meth) acrylamide, N- (2,2,2-trichloro-1-hydroxyethyl) ( (Meth) acrylamide, N- (2-dimethylaminoethyl) (meth) acrylamide N- (3-dimethylaminopropyl) (meth) acrylamide, N- [3-bis (2-hydroxyethyl) aminopropyl] (meth) acrylamide, N- (1,1-dimethyl-2-dimethylaminoethyl) ( (Meth) acrylamide, N- (2-methyl-2-phenyl-3-dimethylaminopropyl) (meth) acrylamide, N- (2,2-dimethyl-3-dimethylaminopropyl) (meth) acrylamide, N- (2 -Substituted N-monoalkyl (meth) acrylamides such as morpholinoethyl) (meth) acrylamide, N- (2-amino-1,2-dicyanoethyl) (meth) acrylamide; N, N-dimethyl (meth) acrylamide, N , N-diethyl (meth) acrylamide, N, N-dipropyl (meth) acrylamide, N, N- Isopropyl (meth) acrylamide, N, N-di (n- butyl) (meth) acrylamide, N, N-dialkyl (meth) acrylamide; and the like. Examples of polymers containing a chain amide having an N- (meth) acryloyl group as a monomer unit include a homopolymer of N-isopropylacrylamide and a copolymer of N-isopropylacrylamide (for example, a copolymerization ratio of N-isopropylacrylamide) Is a copolymer exceeding 50% by weight).

  Examples of the cyclic amide having an N- (meth) acryloyl group include N- (meth) acryloylmorpholine and N- (meth) acryloylpyrrolidine. An example of a polymer containing a cyclic amide having an N- (meth) acryloyl group as a monomer unit is an acryloylmorpholine-based polymer. Typical examples of the acryloylmorpholine-based polymer include a homopolymer of N-acryloylmorpholine (ACMO) and a copolymer of ACMO (for example, a copolymer having a copolymerization ratio of ACMO exceeding 50% by weight). In the acryloylmorpholine-based polymer, the ratio of the number of moles of ACMO units to the number of moles of all repeating units is usually 50% or more, and 80% or more (for example, 90% or more, typically 95% or more). Is appropriate. All the repeating units of the water-soluble polymer may be substantially composed of ACMO units. Here, “substantially” typically means that 98% or more of all repeating units are ACMO units.

  The vinyl alcohol-based polymer is typically a polymer containing vinyl alcohol units (VA units) as main repeating units. In the polymer, the ratio of the number of moles of VA units to the number of moles of all repeating units (that is, the degree of saponification) is not particularly limited. The ratio of the number of moles of the VA unit is usually preferably 50% or more, preferably 65% or more, more preferably 70% or more, for example, 75% or more. The kind of repeating unit other than the VA unit is not particularly limited, and examples thereof include a vinyl acetate unit, a vinyl propionate unit, and a vinyl hexanoate unit. A vinyl alcohol polymer (polyvinyl alcohol) in which all repeating units are substantially composed of VA units may be used. Here, “substantially” typically means that 98% or more of all repeating units are VA units.

  As an effect that can be realized by including a water-soluble polymer in the polishing composition disclosed herein, there is an effect of controlling the surface shape of an object to be polished (for example, a silicon wafer) after polishing. For example, an event (roll-off) in which the thickness of the outer peripheral portion (in the vicinity of the edge) is undesirably reduced by polishing can be suppressed, and an effect of improving the flatness of the outer peripheral portion after polishing can be realized. As a preferable water-soluble polymer from the viewpoint of obtaining such an effect, a vinylpyrrolidone-based polymer may be mentioned. Of these, polyvinylpyrrolidone is preferable.

The weight average molecular weight (Mw) of the water-soluble polymer is not particularly limited, and for example, 150 × 10 ⁴ or less, usually 100 × 10 ⁴ or less is appropriate. From the viewpoint of filterability and detergency of the polishing composition, the Mw of the water-soluble polymer is preferably 50 × 10 ⁴ or less, more preferably 30 × 10 ⁴ or less, and 15 × 10 ⁴ or less (for example, 8 × 10 4 ⁴ or less) is more preferable. Further, from the viewpoint of improving the surface protection after polishing, usually a water-soluble polymer having Mw of 1 × 10 ⁴ or more (for example, 3 × 10 ⁴ or more) can be preferably used.
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, the molecular weight distribution (Mw / Mn) is preferably 10.0 or less, more preferably 5.0 or less, and even more preferably 3.0 or less.
As Mw and Mn of the water-soluble polymer, values based on gel permeation chromatography (GPC) (aqueous, converted to polyethylene oxide) can be adopted.

  Although it does not specifically limit, content of the water-soluble polymer with respect to 100 weight part of abrasive grains can be 0.01 weight part or more, for example, and 0.05 weight part or more from a viewpoint of obtaining a higher effect. The amount is preferably 0.1 parts by weight or more, more preferably 0.3 parts by weight or more (for example, 0.5 parts by weight or more). Further, the content of the water-soluble polymer with respect to 100 parts by weight of the abrasive grains can be, for example, 40 parts by weight or less, and 20 parts by weight or less is appropriate from the viewpoint of polishing rate, detergency, etc., and 15 parts by weight or less. Is preferably 10 parts by weight or less.

  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 chelating agents are more preferred. Of these, ethylenediaminetetrakis (methylenephosphonic acid) and diethylenetriaminehexaacetic acid are preferable. A particularly preferred chelating agent is ethylenediaminetetrakis (methylenephosphonic acid). A chelating agent 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.

<Application>
The polishing composition 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. For example, the present invention can be applied to a silicon wafer lapping process, a preliminary polishing process, a final polishing process, and the like.
The shape of the object to be polished is not particularly limited. The polishing composition disclosed herein can be preferably applied to polishing a polishing object having a flat surface such as a plate shape or a polyhedron shape.

<Polishing composition>
The polishing composition disclosed herein is typically supplied to a polishing object in the form of a polishing liquid containing the polishing composition, and used for polishing the polishing object. The polishing composition disclosed herein may be used, for example, as a polishing liquid after being diluted (typically diluted with water) or as it is as a polishing liquid. Also good. That is, the concept of the polishing composition in the technology disclosed herein includes a polishing composition (working slurry) that is supplied to a polishing object and used for polishing the polishing object, and diluted for use in polishing. And a concentrated liquid (working slurry stock solution). The concentration ratio of the concentrated liquid can be, for example, about 2 to 100 times on a volume basis, and usually about 5 to 50 times is appropriate.

The pH of the polishing composition 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. As the pH of the polishing liquid increases, the polishing rate tends to improve. On the other hand, the pH of the polishing liquid is suitably 12.0 or less from the viewpoint of preventing the dissolution of silica particles as abrasive grains and suppressing the reduction of the mechanical polishing action by the abrasive grains. It is preferably 8 or less, more preferably 11.5 or less, and even more preferably 11.0 or less.
In addition, pH of polishing composition uses the pH meter (For example, the glass electrode type hydrogen ion concentration indicator (model number F-23) by Horiba, Ltd.), standard buffer (phthalate pH buffer solution pH: 4.01 (25 ° C), neutral phosphate pH buffer pH: 6.86 (25 ° C), carbonate pH buffer pH: 10.01 (25 ° C)) It can be grasped by measuring the value after the glass electrode is put into the composition for polishing liquid and stabilized for 2 minutes or more. The same applies to the pH of each agent constituting the polishing composition production kit, the initial pH of the above-mentioned mixed solution, and the like.

<Polishing composition manufacturing kit>
The polishing composition manufacturing kit disclosed herein contains the constituents of the polishing composition as described above divided into two or more agents. These multiple agents are stored separately in the kit. From the viewpoint of convenience, cost reduction, etc. during production, distribution, storage, etc., the above kit can produce a polishing composition by mixing these plural agents and a diluent solvent (preferably water). It is preferable to be configured. Although it does not specifically limit, the quantity of the dilution solvent used at this time can be 1 time or more of the sum total volume of the some agent contained in the said kit on a volume basis. That is, the concentration ratio of the kit with respect to the polishing composition may be 2 times or more. This concentration rate can be set to, for example, about 2 to 100 times, and usually about 5 to 60 times is appropriate. In the kit according to a preferred embodiment, the concentration factor is 10 to 50 times, for example, 15 to 40 times.

  The number of agents constituting the kit disclosed herein is not particularly limited. From the viewpoint of stabilizing the quality of the polishing composition to be manufactured and simplifying the manufacturing process of the polishing composition, the above-mentioned essential components (abrasive grains, strong base and weak acid salt) are usually two agents or It is preferable to make a kit having a structure divided into three agents. The optional component used as necessary may be added to any one or more of the agents containing these essential components, or may be attached as a separate agent from these agents.

  The plurality of agents constituting the kit have an initial pH of 8.0 to 11.8 when the mixture is prepared by combining the plurality of agents into one (for example, 8.0 to 11). .5 or less) is preferable. That is, it is preferable that the constituents of the polishing composition are distributed among a plurality of agents included in the kit so as to satisfy the initial pH. According to such a kit, a polishing composition exhibiting good pH maintenance can be suitably produced. In addition, silica particles can be effectively prevented from dissolving because it is difficult for the silica particles to be temporarily exposed to excessively high pH (for example, 12 or more) during the production of the polishing composition using the kit. can do. This is advantageous for improving the polishing rate. The initial pH of the mixed solution is 9.0 or more and 11.0 or less (preferably 9.5 or more and 11.0 or less, more preferably 10.0 or more and 10.8 or less, for example, 10.2 or more and 10.8 or less). According to the kit configured as described above, one or more of the above-described effects can be better exhibited.

  Here, the initial pH of the mixed solution refers to a pH measured within 3 hours for a sample obtained by stirring the plurality of agents together for about 30 minutes under an environment of about 25 ° C. The operation of combining the plurality of agents into one is performed so that the time from the start to the end of the operation is within one hour. This operation can be, for example, an operation of adding the first composition containing at least one agent to the second composition containing the remaining agent. The first composition may be added all at once as long as the time from the start to the end of the addition to the second composition is within 1 hour, may be added in several portions, or continuously. May be added.

  In a kit configured to produce a polishing composition using a plurality of agents and a diluting solvent (for example, water), it was prepared so as to contain the diluting solvent in an amount ratio similar to that of the polishing composition. The initial pH of the mixed solution is preferably in the above range. In such a mixed solution, for example, at least one of a plurality of agents is diluted with water to prepare a second composition, and the first composition composed of the remaining agents is added to the second composition. It can be prepared by stirring and mixing.

  In addition, the preparation conditions of the said liquid mixture and its initial pH are a parameter | index which shows the characteristic of the kit disclosed here, Comprising: The actual usage aspect of this kit is not restrict | limited. Accordingly, in the production of the polishing composition using the kit disclosed herein, the mode of mixing a plurality of agents contained in the kit is not particularly limited. For example, the total amount of all agents can be mixed at once. Or you may add the whole quantity or one part quantity of one part agent at the timing different from another agent. Moreover, there is no restriction | limiting in particular also in the time which performs operation which combines the some agent contained in the said kit. Each agent may be mixed after appropriately diluted. For the mixing, a known mixing device such as a blade-type stirrer, an ultrasonic disperser, or a homomixer can be used.

As a preferred example of the polishing composition manufacturing kit disclosed herein, a kit containing the above-mentioned essential components separately for agent A and agent B can be mentioned. Such a kit can be typically configured as a two-part kit consisting of agent A and agent B. Alternatively, it may be configured as a three- or more-drug kit further provided with other agents containing optional components used as necessary.
When a polishing composition production kit for producing a polishing composition containing a water-soluble polymer is configured as a two-component type or a three-component type or more kit as described above, the water-soluble polymer is: It may be contained in the agent, may be contained in the B agent, may be contained in both the A agent and the B agent, or may be contained in agents other than the A agent and the B agent.

<A agent>
The agent A preferably contains at least abrasive grains (here, silica particles) and further contains a strong base. The silica particles contained in the agent A may be the total amount or a part of the amount of silica particles contained in the polishing composition. For example, an embodiment in which the entire amount of silica particles is contained in the agent A is preferable.

The content Ws _A [wt%] of the abrasive grains (silica particles) in the agent A can be, for example, 0.1 wt% or more, preferably 0.2 wt% or more, more preferably 0.5 wt%. That's it. From the viewpoint of convenience, cost reduction, etc. during production, distribution, storage, etc., it is usually appropriate to set Ws _A to 1% by weight or more, and 3% by weight or more, and even 5% by weight or more. Good. From the viewpoint of dispersion stability and the like, Ws _A is usually 50% by weight or less, preferably 40% by weight or less, more preferably 30% by weight or less, still more preferably 20% by weight or less, for example 10%. % By weight or less.

  When agent A contains a strong base, the amount of the strong base may be the total amount of the strong base contained in the polishing composition or a partial amount. For example, an embodiment in which a part of the strong base is contained in the agent A is preferable. The remaining amount of strong base may be contained in B agent, may be contained in agents other than A agent and B agent, or may be contained separately in two or more agents other than A agent. Good. The molar amount of the strong base contained in the agent A can be, for example, 25% or more of the total molar amount of the strong base contained in the polishing composition, and is usually suitably 30% or more. , 40% or more, preferably 55% or more (for example, 65% or more, more preferably 70% or more). Thus, a kit that provides a polishing composition with better pH maintenance can be realized.

From the viewpoint of preventing the dissolution of silica particles as abrasive grains and suppressing the reduction of the mechanical polishing action by the abrasive grains, the pH of the agent A is suitably 12.0 or less, preferably 12. It is less than 0, more preferably 11.8 or less, for example 11.6 or less. The lower limit of the pH of the agent A is not particularly limited, but is usually preferably 7.5 or more and more preferably 8.0 or more from the viewpoint of dispersion stability. From the viewpoint of the pH maintenance property and polishing rate of the polishing composition, it is usually advantageous to set the pH of the agent A to 9.0 or more, preferably 10.0 or more, and preferably 10.5 or more. (For example, 11.0 or more) is more preferable. The content Wb _A [wt%] of the strong base in the agent _A can be set so that the above-described preferable pH is realized.

In the art disclosed herein, the ratio of Wb _A [wt%] for Ws _{A [wt%] (Wb A / Ws A} ) is not particularly limited. From the viewpoint of obtaining a polishing composition exhibiting good pH maintainability, it is usually appropriate to set (Wb _A / Ws _A ) to 0.15 or more, preferably 0.20 or more. More preferably, it should be .22 or more. In a preferred embodiment, (Wb _A / Ws _A ) can be 0.25 or more and 1.00 or less. According to such an embodiment, a polishing composition with improved one or both of pH maintenance and polishing rate can be produced. From the viewpoint of the dispersion stability of the agent A, (Wb _A / Ws _A ) is advantageously 0.80 or less, preferably 0.60 or less, and 0.50 or less (for example, 0.8. 45 or less) is more preferable.

<B agent>
The agent B contains at least a weak acid salt (preferably an alkali metal carbonate). The weak acid salt contained in the agent B may be the total amount of the weak acid salt contained in the polishing composition or a partial amount thereof. For example, the aspect in which the whole quantity of weak acid salt is contained in B agent is preferable.

Content of the weak acid salt in B agent is not specifically limited. The molar amount of the weak acid salt contained per liter of the agent B, that is, the weak acid salt concentration Ma _B [mol / L] of the agent B can be, for example, 0.0001 mol / L or more, preferably 0.0005. Mol / L or more, more preferably 0.001 mol / L or more. From the viewpoint of convenience, cost reduction, etc. in the manufacture, distribution, storage, etc. of the kit, Ma _B [mol / L] can be 0.01 mol / L or more, and 0.05 mol / L or more. Or 0.1 mol / L or more. The upper limit of Ma _B [mol / L] may be set so that the weak acid salt can be stably dissolved. For example, Ma _B [mol / L] can be 5 mol / L or less, and usually 2 mol / L or less (for example, 1 mol / L or less) is appropriate.

  The technique disclosed here can be preferably implemented in a mode in which the agent B contains a strong base in addition to the weak acid salt. Thus, the B agent of the composition containing a combination of a weak acid salt and a strong base can exhibit a buffering action. By forming the B agent as a buffer solution, an event that the pH of the mixed solution temporarily increases greatly when the B agent or its diluted solution and another agent (for example, the A agent) are mixed (the pH jumps up). Event) can be significantly suppressed. This is preferable because a kit in which the initial pH of the mixed solution is suppressed to 11.8 or less can be easily formed.

  When agent B contains a strong base, the amount of the strong base may be the total amount of the strong base contained in the polishing composition or a partial amount. For example, an embodiment in which a part of the strong base is contained in the agent B is preferable. The remaining amount of the strong base may be contained in agent A, may be contained in agents other than agent A and agent B, or may be contained separately in two or more agents other than agent B. Good.

In the technique disclosed herein, the ratio of the strong base concentration Mb _B [mol / L] to the weak acid salt concentration Ma _B [mol / L] of the B agent (Mb _B / Ma _B ) is not particularly limited. It can be set to 0 or more and 1.00 or less. Here, (Mb _B / Ma _B ) being 0 means that the B agent does not contain a strong base. From the viewpoint of avoiding an event in which the initial pH of the mixed solution becomes excessively high, it is usually appropriate that (Mb _B / Ma _B ) is greater than 0 and not greater than 1.00. It is preferably set to 00 or less, for example, 0.05 to 0.95. In a preferred embodiment, (Mb _B / Ma _B ) can be set to, for example, 0.10 or more and 0.90 or less. According to such an embodiment, a polishing composition with improved one or both of pH maintenance and polishing rate can be produced. (Mb _B / Ma _B ) may be 0.10 or more and 0.80 or less, and may be 0.20 or more and 0.60 or less. According to the B agent having such a composition, particularly good results can be realized.

  The technique disclosed here can be preferably implemented in a mode in which a part of the total amount of the strong base contained in the polishing composition is contained in the agent A and the remaining part is contained in the agent B. That is, a polishing composition production kit in which the total amount of the strong base contained in the polishing composition is distributed to the agent A and the agent B is preferable. In this case, the molar amount of the strong base contained in the agent A can be, for example, 25% to 98% of the total molar amount of the strong base contained in the polishing composition, and usually 30% to 95%. % Is appropriate. By this, it is possible to avoid excessive increase in pH in the production process of the polishing composition using these A agent and B agent, to prevent the abrasive grains from being consumed, and to exert a mechanical polishing action appropriately. Can do. In addition, a polishing composition with one or both of pH maintenance and polishing rate improved can be produced. From these viewpoints, the molar amount of the strong base contained in the agent A is preferably 40% to 90% of the total molar amount of the strong base contained in the polishing composition, and 55% to 85% (for example, 65%). -85%, more preferably 70% -80%). Thus, a kit that provides a polishing composition with better pH maintenance can be realized.

  The aspect which manufactures polishing composition using the kit containing A agent and B agent of such a structure is not restrict | limited in particular. In a preferred embodiment, a polishing composition is produced using these agent A and agent B and a diluent solvent such as water. In manufacturing such a polishing composition, the agent A and the agent B may be mixed as they are and then diluted, or one of the agents A and B may be diluted and then mixed with the other agent. Both agents may be mixed after dilution.

  The production of the polishing composition using the kit containing the agent A and the agent B is preferably carried out in an embodiment including, for example, adding the first composition containing the agent A to the second composition containing the agent B. can do. The first composition may be the agent A itself, may be prepared by diluting the agent A with a diluent solvent such as water, or may be prepared by adding another agent to the agent A. The second composition may be the B agent itself, or may be prepared by diluting the B agent with a diluent solvent such as water, or prepared by adding another agent to the B agent. As a preferred embodiment, first, the second composition is prepared by diluting the B agent with water, and the first composition containing the A agent (which may be the A agent itself) is added to the second composition. Can be mentioned. According to this aspect, aggregation of the silica particles contained in the first composition can be suitably prevented. Moreover, since it is easy to suppress the jump of pH when a 1st composition and a 2nd composition are match | combined, it is preferable.

<Polishing>
The polishing composition manufacturing kit disclosed herein can be used for polishing a polishing object, for example, in an embodiment including the following operations.
That is, a polishing composition (working slurry) produced using any of the kits disclosed herein is prepared. Next, the polishing composition is supplied to the object to be polished and polished by a conventional method. For example, a polishing object is set in a general polishing apparatus, and the polishing composition is supplied to the surface (polishing object surface) of the polishing object through a polishing pad of the polishing apparatus. Typically, while continuously supplying the polishing composition, the polishing pad is pressed against the surface of the object to be polished, and both are relatively moved (for example, rotated). 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 polyurethane foam type, non-woven fabric type, suede type, those containing abrasive grains, and those not containing abrasive grains may be used. Further, as the polishing apparatus, a double-side polishing apparatus that simultaneously polishes both surfaces of an object to be polished, or a single-side polishing apparatus that polishes only one surface of the object to be polished may be used.

  Although it does not specifically limit, It is preferable to use the polishing composition manufactured using the kit disclosed here for polishing within a relatively short period of time after the manufacture. By this, the advantage of making the kit for manufacturing this polishing composition into a multi-drug type (that is, a constitution comprising a plurality of agents) can be better utilized. The period from the production of the polishing composition to its use can be, for example, within 2 weeks, usually within 3 days, preferably within 24 hours, preferably within 12 hours. It is more preferable. The period may be within 3 hours, and may be within 1 hour. Or you may supply the manufactured polishing composition to a grinding | polishing target object, manufacturing the said polishing composition using a kit continuously.

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

  The polishing composition manufacturing kit disclosed herein can be excellent in storage stability by increasing the number of components of the polishing composition. Moreover, according to this polishing composition manufacturing kit, a polishing composition that has high pH maintainability and can exhibit stable polishing performance with little change in performance even when used, for example, can be manufactured. According to a kit according to a preferred embodiment, a polishing composition can be produced that exhibits a pH maintaining property equivalent to that of a polishing composition produced by diluting a one-part concentrated solution and further improves the polishing rate. .

  The polishing composition disclosed herein can achieve both high pH maintenance and high polishing rate. Taking advantage of this feature, for example, it can be preferably applied to preliminary polishing of a lapped silicon wafer. In the preliminary polishing step, since the required polishing rate is higher than that in the final polishing step, the scraped silicon is dissolved in the polishing composition in a large amount. Accordingly, the polishing composition tends to contain a large amount of silicate ions. This acts to lower the pH of the polishing composition. When the polishing composition is recycled, the above action is particularly strong. The polishing composition disclosed herein can have a small pH fluctuation (high pH maintainability) even under such circumstances.

  Several examples relating to the present invention will be described below, but the present invention is not intended to be limited to those shown in the examples.

<Experimental example 1>
<Preparation of polishing composition production kit>
Example 1
Colloidal silica, tetramethylammonium hydroxide (TMAH) and ion-exchanged water are stirred and mixed at room temperature of about 25 ° C. for about 30 minutes, so that the content of colloidal silica (Ws _A ) is 8.8% by weight and TMAH is contained. An agent _A having an amount (Wb _A ) of 3.092% by weight (corresponding to a concentration of 0.357 mol / L) was prepared. Colloidal silica having an average primary particle diameter of 35 nm and an average secondary particle diameter of 66 nm was used.
TMAH concentration (Mb _B ) 0.123 mol / L, potassium carbonate concentration (Ma _B ) by stirring and mixing TMAH, potassium carbonate (K ₂ CO ₃ ) and ion-exchanged water at room temperature of about 25 ° C. for about 30 minutes. A 0.217 mol / L B agent was prepared.
Said A agent and said B agent were prepared for each same volume in a separate container. In this way, a two-component type polishing composition manufacturing kit comprising the agent A and the agent B was obtained.

(Example 2)
In Example 1, the potassium carbonate concentration (Ma _B ) of the B agent was changed as shown in Table 1. Otherwise in the same manner as in Example 1, a two-component polishing composition production kit was obtained.

(Example 3)
In Example 1, the potassium carbonate concentration (Ma _B ) of the B agent was changed as shown in Table 1. Otherwise in the same manner as in Example 1, a two-component polishing composition production kit was obtained.

(Example 4)
In this example, colloidal silica having an average primary particle diameter of 52 nm and an average secondary particle diameter of 96 nm was used in preparing the agent A. Further, the TMAH concentration (Wb _A ) of the agent _A was changed as shown in Table 1. Otherwise in the same manner as in Example 3, a two-component polishing composition production kit was obtained.

( Reference Example 5)
In Example 1, the colloidal silica content (Ws _A ) and TMAH content (Wb _A ) of the agent _A were changed as shown in Table 1, respectively. Further, the TMAH concentration (Mb _B ) of the B agent was changed as shown in Table 1. Otherwise in the same manner as in Example 1, a two-component polishing composition production kit was obtained.

( Reference Example 6)
In Example 2, the TMAH content (Wb _A ) of the agent _A and the TMAH concentration (Mb _B ) of the agent _B were changed as shown in Table 1, respectively. Otherwise in the same manner as in Example 2, a two-component polishing composition production kit was obtained.

(Comparative Example 1)
In Example 3, the TMAH content (Wb _A ) of Agent _A and the TMAH concentration (Mb _B ) of Agent _B were changed as shown in Table 1, respectively. Otherwise in the same manner as in Example 3, a two-component polishing composition production kit was obtained.

<Preparation of concentrate>
(Comparative Example 2)
Colloidal silica, TMAH, potassium carbonate and ion-exchanged water were stirred and mixed at room temperature of about 25 ° C. for about 30 minutes, whereby colloidal silica content was 8.8 wt%, TMAH content was 4.163 wt% (concentration 0.480). Equivalent to mol / L.), A one-pack type concentrate having a composition with a potassium carbonate concentration of 0.217 mol / L was prepared. The same colloidal silica as in Example 1 was used.

(Comparative Example 3)
In Comparative Example 2, the TMAH content and the potassium carbonate concentration were changed as shown in Table 1, respectively. Otherwise in the same manner as in Comparative Example 2, a one-component concentrate was obtained.

Tables 1 and 2 show the outlines of the polishing composition production kit and the concentrated liquid according to each of the above examples. In Table 1, for the sake of convenience, an outline of the concentrated liquid according to Comparative Examples 2 and 3 is displayed in the column “A Agent”. Moreover, when the volume of A agent and B agent which comprise each kit which concerns on Examples 1-4, Reference Examples 5, 6 and Comparative Example 1 is 1 liter in total (that is, each kit is 0.5 liter of A agent) TMAH in agent A relative to the molar amount of total TMAH and total potassium carbonate contained in each kit and the molar amount of total TMAH contained in each kit. The ratio to the molar amount is shown in Table 2. Table 2 shows the molar amount of TMAH and the molar amount of potassium carbonate contained in 1 liter of each concentrated liquid according to Comparative Examples 2 and 3.

<Preparation of polishing composition>
(Examples 1-4, Reference Examples 5, 6 and Comparative Example 1)
The agent B of the polishing composition production kit according to each example was diluted 29 times (volume basis) with ion-exchanged water. The A agent was added to the B agent diluted solution at once (volume ratio of the A agent: B agent diluted solution was 1:29), and the mixture was stirred and mixed to prepare a polishing composition.

(Comparative Examples 2 and 3)
A polishing composition was prepared by diluting the concentrated liquid according to each example 30 times (volume basis) with ion-exchanged water.

<Polishing of silicon wafer>
The polishing composition according to each example was directly used as a polishing liquid, and the surface of the polishing object (test piece) was polished under the following conditions (polishing condition 1). As a test piece, a silicon wafer having a diameter of 300 mm (conductivity type: P type, crystal orientation: <100>, resistivity: 0.1 Ω · cm or more and less than 100 Ω · cm) with a double-side polishing apparatus having a surface roughness of 0.5 nm to After adjusting the thickness to 1.5 nm, washing and drying it, one cut into a square shape having a side of 60 mm was used.

(Polishing condition 1)
Polishing device: Single-side polishing device manufactured by ENGIS, model “EJ-380IN”
Polishing pressure: 51.6 kPa
Surface plate rotation speed: 50 rotations / minute Carrier rotation speed: 50 rotations / minute Polishing pad: Product name “MH S-15A” manufactured by Nitta Haas
Polishing liquid supply rate: 50 mL / min. Test piece (500 mL of polishing liquid used in circulation)
Polishing environment temperature: 25 ° C

<Average polishing efficiency measurement and pH maintenance test>
While circulating and using the polishing liquid under the above polishing condition 1, polishing was continuously performed 6 times for 15 minutes, and the polishing amount [μm / min] per minute was calculated for each of the first to sixth times. did. The arithmetic average value of these six polishing amounts [μm / min] was defined as the average polishing efficiency [μm / min].
Also, the pH of the polishing liquid at the beginning of the first polishing (initial pH) and the pH of the polishing liquid immediately after the end of the sixth polishing (post-pH) are measured, and the difference between the pHs is calculated. did. The smaller the difference value, the better the pH maintainability.
In addition, polishing of the silicon wafer using the polishing composition according to each example was started within 3 hours after the production of the polishing composition. Therefore, in Examples 1 to 4, Reference Examples 5 and 6, and Comparative Example 1, the initial pH of the polishing liquid is obtained by combining the A agent and the B agent of the polishing composition manufacturing kit according to each example. This corresponds to the initial pH of the mixture prepared in the above.

<Storage stability test>
The following storage stability was obtained using samples A of the polishing composition production kit according to Examples 1 to 4, Reference Examples 5 and 6, and Comparative Example 1 as well as the concentrated liquid according to Comparative Examples 2 and 3 as samples. The period during which the quality can be stably maintained (stability holding period) was evaluated by the property test.
That is, 300 mL of each sample was placed in a polypropylene container and stored in an air bath managed in an atmosphere of 43 ° C. These samples were periodically taken out from the air bath and visually observed to confirm the presence or absence of silica aggregation in the samples. The test period was a maximum of one year. For samples in which silica aggregation was not confirmed even one year after the start of the test, the storage stability (stability retention period) was evaluated as “one year or more”. For samples in which silica aggregation was confirmed within one year from the start of the test, the period until the last observation point in which silica aggregation was not confirmed was defined as the stability retention period.
In addition, since the B agent of each kit does not contain silica particles, there is no problem of silica aggregation during storage. Therefore, the stability holding period of the agent A can be regarded as the stability holding period of the kit.

  The results obtained by the above measurements or tests are shown in Table 1.

As shown in Table 1, all of the kits according to Examples 1 to 4 and Reference Examples 5 and 6 have a stability retention period of 1 year or more, and are clearly compared with the concentrated solutions of Comparative Examples 2 and 3. Excellent storage stability. According to the kits of Examples 1 to 4 and Reference Examples 5 and 6 in which the initial pH is in the range of 8.0 to 11.8, it is better than the kit of Comparative Example 1 having an initial pH of more than 11.8. A polishing composition (polishing liquid) exhibiting pH maintainability was obtained. According to the kits of Examples 1 to 4 having an initial pH of 11.0 or less, a polishing composition showing even better pH maintainability was obtained. Particularly good results were obtained with the kits of Examples 1 and 2 having an initial pH of 10.5 or less.

By comparing Examples 1 to 4 with Reference Examples 5 and 6 and Comparative Example 1, (Wb _A / Ws _A ) is set to 0.25 or more and (Mb _B / Ma _B ) is set to 1.00 or less. Is effective in improving pH maintenance. In Example 2 and Reference Example 6, the composition of the polishing composition (polishing liquid) was the same, but the pH maintainability was clearly higher in Example 2, and the average polishing efficiency was higher in Example 2. The same tendency was observed in the comparison between Example 3 and Comparative Example 1.
Further, from the comparison between Examples 1 to 4, Reference Examples 5 and 6 and Comparative Example 1, the ratio of the TMAH amount in the agent A to the total TMAH amount is 30% or more, further 50% or more (particularly 60% or more). It turns out that it is effective for improvement of pH maintenance property.

  Further, as can be seen from the comparison between Example 1 and Comparative Example 2 in which the composition of the polishing composition (polishing liquid) is the same, polishing produced using the kit of Example 1 to which the technology disclosed herein was applied. According to the composition for polishing, the average polishing efficiency could be further improved without impairing the pH maintenance property of the polishing composition of Comparative Example 2.

<Experimental example 2>
<Preparation of polishing composition production kit>
(Example 7)
Colloidal silica, TMAH, polyvinyl pyrrolidone (PVP) and ion-exchanged water are stirred and mixed at room temperature of about 25 ° C. for about 30 minutes, so that the content of colloidal silica (Ws _A ) is 8.8% by weight and the content of TMAH An agent _{A having a} (Wb _A ) of 3.092% by weight (corresponding to a concentration of 0.357 mol / L) and a PVP content of 0.05% by weight was prepared. The same colloidal silica as in Example 1 was used. As the PVP, one having an Mw of about 45,000 was used.
Agent B was prepared in the same manner as in the preparation method of Agent B in Example 2.
Said A agent and said B agent were prepared for each same volume in a separate container. In this way, a two-component type polishing composition manufacturing kit comprising the agent A and the agent B was obtained.

(Example 8)
In Example 7, the potassium carbonate concentration (Ma _B ) of the B agent was changed as shown in Table 3. Otherwise in the same manner as in Example 7, a two-component polishing composition production kit was obtained.

Example 9
By stirring and mixing TMAH, potassium carbonate (K ₂ CO ₃ ), PVP and ion-exchanged water at room temperature of about 25 ° C. for about 30 minutes, TMAH concentration (Mb _B ) 0.123 mol / L, potassium carbonate concentration (Ma _B ) A B agent having 0.326 mol / L and a PVP content of 0.05% by weight was prepared. The same PVP as in Example 7 was used.
Otherwise in the same manner as in Example 3, a two-component polishing composition production kit was obtained.

<Preparation of polishing composition>
The agent B of the polishing composition production kit according to each example was diluted 29 times (volume basis) with ion-exchanged water. The A agent was added to the B agent diluted solution at once (volume ratio of the A agent: B agent diluted solution was 1:29), and the mixture was stirred and mixed to prepare a polishing composition.

<Polishing of silicon wafer>
The polishing composition according to each example was directly used as a polishing liquid, and the surface of the polishing object (test piece) was polished under the following conditions (polishing condition 2). As a test piece, a silicon wafer having a diameter of 300 mm (conductivity type: P type, crystal orientation: <100>, resistivity: 0.1 Ω · cm or more and less than 100 Ω · cm) with a double-side polishing apparatus having a surface roughness of 0.5 nm to The product was adjusted to 1.5 nm, washed and dried.

(Polishing condition 2)
Polishing device: Double-side polishing device manufactured by Speedfam, model “DSM20B-5P-4D”
Polishing pressure: 15.0kPa
Upper surface plate rotation speed: -13 rotations / minute Lower surface plate rotation speed: 35 rotations / minute (rotation direction opposite to the upper surface plate)
Internal gear rotation speed: 7 rotations / minute Sun gear rotation speed: 25 rotations / minute Polishing pad: Product name “MH S-15A” manufactured by Nitta Haas
Polishing liquid: A total of 100 L of polishing liquid is circulated at a speed of 4.5 L / min.
Polishing time: 60 minutes

<Outer peripheral flatness evaluation>
In order to evaluate the outer peripheral flatness of the polished silicon wafer, a roll-off amount (ROA; Roll-off Amount) serving as an index was measured. The silicon wafer ROA measurement method according to the present case will be specifically described below. First, the silicon wafer polished under the above polishing condition 2 was set in a flatness inspection apparatus (“Nanometro 300TTM” manufactured by Kuroda Seiko Co., Ltd.). At this time, when the notch portion of the silicon wafer was set to 0 °, a straight line indicating a direction of 45 ° in the clockwise direction was set as the measurement region for the flatness measurement. FIG. 1 shows an example of a graph obtained by measuring the flatness. The horizontal axis in FIG. 1 indicates the distance from the outer peripheral edge of the silicon wafer, and the vertical axis indicates the amount of displacement of the shape of the silicon wafer surface. As shown in FIG. 1, the position 3 mm to 6 mm from the outer peripheral edge of the silicon wafer is a relatively flat region. This region (3 mm to 6 mm position) is taken as a reference region, and a straight line (reference straight line) that approximates the amount of shape displacement in the region is drawn using the least square method. Next, using a point on the reference line at a position 1 mm from the outer peripheral edge as a reference point, a difference between the displacement amount of the silicon wafer at the 1 mm position and the reference point is measured, and this is calculated as a roll-off amount (ROA) of the silicon wafer. ).

  Table 3 shows the results of the evaluation of the outer peripheral portion flatness obtained using the polishing compositions according to Examples 2, 3 and 7 to 9. In addition, Table 3 shows the results obtained by the measurement or test according to Experimental Example 1 described above using the polishing composition.

  As shown in Table 3, it is clear from the comparison between Examples 2 and 7 that by adding PVP to the agent A, the ROA after polishing is clearly reduced and the outer peripheral flatness is improved. It was. The same tendency was observed in the comparison between Examples 3 and 8. Further, the comparison between Examples 3 and 9 shows that the addition of PVP to the agent B decreases the ROA after polishing and improves the outer peripheral flatness. In addition, it was confirmed that Examples 7 to 9 in which PVP was added to the A agent or the B agent generally showed good average polishing efficiency, and good pH maintenance and storage stability.

  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)

A polishing composition production kit for producing a polishing composition comprising silica particles as abrasive grains, a strong base and a weak acid salt,
With multiple agents stored separately from each other,
Ri der initial pH of the mixture is 8.0 or more 11.8 in the case of preparing a mixed solution in accordance with the one of the plurality of agents,
As the plurality of agents:
A agent comprising the silica particles and the strong base; and
B agent containing the strong base and the weak acid salt;
Including
In the agent A , the relationship between the content Wb _A [wt%] of the strong base and the content Ws _A [wt%] of the silica particles is represented by the following formula (A):
0.25 ≦ (Wb _A / Ws _A ) ≦ 1.00 (A);
The filling,
In the agent _B , the relationship between the strong base concentration Mb _B [mol / L] and the weak acid salt concentration Ma _B [mol / L] is the following formula (B):
0 <(Mb _B / Ma _B ) ≦ 1.00 (B);
Satisfies a polishing composition manufacturing kit. The molar amount of the strong base contained in the A agent is 95% or less than 30% of the molar amount of all strong base contained in the polishing composition kit for producing the composition for polishing according to claim 1 Product manufacturing kit. The polishing composition production kit according to claim 1 or 2 , wherein the weak acid salt includes a weak acid salt having at least one acid dissociation constant (pKa) value in the range of 8.0 to 11.8. The polishing according to any one of claims 1 to 3 , comprising at least one selected from the group consisting of carbonates, bicarbonates, borates, phosphates, and phenol salts as the weak acid salts. A kit for producing a composition. The polishing composition manufacturing kit according to any one of claims 1 to 4, wherein the weak acid salt includes a weak acid salt whose anion component is carbonate ion or hydrogen carbonate ion.   The strong base includes at least one selected from the group consisting of alkali metal hydroxide, quaternary ammonium hydroxide, alkylamine, quaternary phosphonium hydroxide, and ammonia. The kit for manufacturing the polishing composition according to one item. A method for producing a polishing composition, comprising using the kit for producing a polishing composition according to any one of claims 1 to 6. Diluting the agent B with water to prepare a second composition; and adding the first composition containing the agent A to the second composition;
The manufacturing method of Claim 7 containing this.   Polishing composition manufactured by the method of Claim 7 or 8.

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