JP6761025B2 - Polishing composition set, pre-polishing composition, and silicon wafer polishing method - Google Patents

Description

The present invention relates to a polishing composition set, a pre-polishing composition, and a method for polishing a silicon wafer.

In order to reduce the haze on the surface of a silicon wafer, various techniques related to polishing compositions and polishing methods have been proposed (see, for example, Patent Documents 1 and 2). However, in recent years, the level of demand for surface quality of silicon wafers has become higher and higher, and further improvements have been required for these technologies.

Japanese Patent Publication No. 5204960 Japanese Patent Publication No. 2015 No. 185672

The present invention solves the above-mentioned problems of the prior art, reduces haze, and can realize a high-quality surface to be polished. A polishing composition set, a pre-polishing composition, and a method for polishing a silicon wafer. The challenge is to provide.

In order to solve the above problems, the polishing composition set according to one aspect of the present invention includes the finish polishing composition used in the finish polishing step of performing the finish polishing of the silicon wafer and one step before the finish polishing step. A polishing composition set comprising a pre-polishing composition used in the pre-polishing step, which is a polishing step, wherein the hydrophilicity parameter P1 of the pre-polishing composition obtained in the standard test 1 is less than 100. The gist is that the finish accuracy parameter P2 of the pre-polishing composition obtained in the standard test 2 is 1000 or less, and the polishing processability parameter F1 of the finish polishing composition obtained in the standard test 3 is 80 or less.

Further, the pre-polishing composition according to another aspect of the present invention is a pre-polishing composition used in a pre-polishing step which is a polishing step one step before the finish polishing step of performing finish polishing of a silicon wafer. The gist is that the hydrophilicity parameter P1 required in the standard test 1 is less than 100, and the finishing accuracy parameter P2 required in the standard test 2 is 1000 or less.

Further, the method for polishing a silicon wafer according to another aspect of the present invention includes a finish polishing step for finish polishing the silicon wafer and a pre-polishing step which is a polishing step one step before the finish polishing step. The polishing method of the above, wherein the finish polishing step and the pre-polishing step are performed using the polishing composition set according to the above-mentioned one aspect, or the pre-polishing composition according to the other aspect is used. The gist is to perform the polishing process.

According to the present invention, it is possible to reduce haze and realize a high-quality surface to be polished.

One embodiment of the present invention will be described in detail. The polishing composition set of the present embodiment is used in a finish polishing composition used in a finish polishing step of performing finish polishing of a silicon wafer and in a pre-polishing step which is a polishing step one step before the finish polishing step. The pre-polishing composition is provided. Then, the hydrophilicity parameter P1 of the pre-polishing composition obtained in the standard test 1 is less than 100, and the finishing accuracy parameter P2 of the pre-polishing composition obtained in the standard test 2 is 1000 or less, which is obtained in the standard test 3. The polishing processability parameter F1 of the finish polishing composition is 80 or less.

Further, the pre-polishing composition of the present embodiment is a polishing composition used in the pre-polishing step, which is a polishing step one step before the finish polishing step of performing the finish polishing of the silicon wafer. The hydrophilicity parameter P1 required in the standard test 1 is less than 100, and the finishing accuracy parameter P2 required in the standard test 2 is 1000 or less.

Such a polishing composition set and a pre-polishing composition of the present embodiment can be suitably used for polishing various polishing objects such as simple substance silicon, silicon compounds, metals, and ceramics, and haze is increased. It is possible to realize a low-quality surface to be polished. In addition, it is possible to realize a surface to be polished with few minute defects. In particular, if the polishing composition set or the pre-polishing composition of the present embodiment is used for polishing a silicon wafer, a silicon wafer such as a silicon single crystal wafer having a high-quality surface with low haze can be manufactured. ..

More specifically, in order to realize a high-quality surface to be polished with low haze, a silicon wafer is finish-polished using a finish-polishing composition capable of producing a surface to be polished with low workability and high accuracy. This is very important. For that purpose, the surface to be polished after the completion of the pre-polishing step needs to have an appropriate surface protection property and a surface of good quality (low haze). That is, if pre-polishing is performed so that the surface to be polished after the completion of the pre-polishing step has appropriate surface protection and a surface of good quality, the surface protection is not excessively high and the quality is already good to some extent. Since the surface is made of, the load in the finish polishing process is reduced, and the finish polishing can be performed using a finish polishing composition capable of producing a surface to be polished with low workability and high accuracy. As a result, a high-quality surface to be polished with low haze can be realized. The surface to be polished after the pre-polishing step is preferably of higher quality.

For the above reasons, the pre-polishing composition has the ability to be polished so that the surface to be polished after the pre-polishing process has appropriate hydrophilicity and a surface of good quality. Desired. The hydrophilicity of the surface to be polished after the completion of the pre-polishing step is expressed by the hydrophilicity parameter P1, and this hydrophilicity parameter P1 can be obtained in the standard test 1. Further, the polishing performance of the pre-polishing composition is expressed by the finishing accuracy parameter P2, and this finishing accuracy parameter P2 can be obtained in the standard test 2.

Further, since the composition for finish polishing is required to finish the surface to be polished with high accuracy, its workability is suppressed to a low level. The polishing workability of the finish polishing composition is expressed by the polishing workability parameter F1, and this polishing workability parameter F1 can be obtained in the standard test 3.
The standard tests 1, 2 and 3 for obtaining the hydrophilicity parameter P1, the finish accuracy parameter P2, and the polishability parameter F1 will be described in detail later.

The pre-polishing step in the present invention means a polishing step one step before the finish polishing step among the plurality of polishing steps included in the silicon wafer polishing method. Therefore, when the polishing method of the silicon wafer includes, for example, three polishing steps of a primary polishing step, a secondary polishing step, and a finish polishing step, which are preliminary polishing steps, the secondary polishing step corresponds to the pre-polishing step. To do. Further, when the polishing method of the silicon wafer includes, for example, two polishing steps of a primary polishing step and a finish polishing step, which are preliminary polishing steps, the primary polishing step corresponds to the pre-polishing step.

The pre-polishing composition, the finish polishing composition, and the polishing composition set of the present embodiment will be described in detail below. Unless otherwise specified, the various operations and physical property measurements described below were performed under the conditions of room temperature (20 ° C. or higher and 25 ° C. or lower) and relative humidity of 40% or higher and 50% or lower.

1. 1. Pre-polishing composition The pre-polishing composition used in the pre-polishing process of silicon wafers has a hydrophilicity parameter P1 required in standard test 1 of less than 100 and a finishing accuracy parameter P2 required in standard test 2 of 1000. It is as follows. The standard tests 1 and 2 will be described below.

1-1 About standard test 1 The hydrophilicity parameter P1 is obtained in standard test 1 in which the following steps a1, a2, a3, and a4 are performed in this order.

[Standard test 1]
(A1) Using the pre-polishing composition, a silicon test piece of the same material as the silicon wafer to be polished is polished. As the silicon test piece, a circular wafer may be used, or a chip cut into a quadrangle may be used. For polishing the silicon test piece, for example, a tabletop polishing machine EJ-380IN manufactured by Nippon Engis Co., Ltd. and a polishing pad POLYPAS27NX manufactured by Fujibo Co., Ltd. can be used. The polishing conditions for polishing the silicon test piece are, for example, a polishing load of 16 kPa, a surface plate rotation speed of 30 rpm, a carrier rotation speed of 30 rpm, a polishing time of 2 min, a pre-polishing composition supply speed of 30 mL / min, and a pre-polishing composition. The temperature can be 20 ° C.

(A2) The polished surface of the silicon test piece is washed with pure water to wash away the pre-polishing composition.
(A3) When the silicon test piece is circular, the diameter of the silicon test piece washed with pure water is in the vertical direction, and when the silicon test piece is square, one diagonal line is in the vertical direction. Let stand for 30 seconds in a vertical position, measure the length of the area of the diameter or diagonal where the surface of the silicon test piece is not wet with pure water, and use that length as the water repellent distance.

(A4) From the measured water repellency distance, the hydrophilicity parameter P1 of the prepolishing composition is calculated based on the following formula.
Hydrophilic parameter P1 = {(diameter of silicon test piece or diagonal length [mm])-(water repellent distance [mm])} / (diameter of silicon test piece or diagonal length [mm]) × 100

1-2 Standard test 2 The finishing accuracy parameter P2 is obtained in the standard test 2 in which the following steps b1, b2, and b3 are performed in this order.

[Standard test 2]
(B1) Using the pre-polishing composition, a silicon wafer test piece of the same material as the silicon wafer to be polished (that is, a silicon wafer for parameter measurement) is polished. For polishing the silicon wafer test piece, for example, a polishing machine PNX-332B manufactured by Okamoto Machinery Works, Inc. and a polishing pad POLYPAS27NX manufactured by Fujibo Co., Ltd. can be used. The polishing conditions for polishing the silicon wafer test piece are, for example, a polishing load of 15 kPa, a surface plate rotation speed of 30 rpm, a carrier rotation speed of 30 rpm, a polishing time of 2 min, a pre-polishing composition supply speed of 2 L / min, and a pre-polishing composition. The temperature of the object can be 20 ° C. and the temperature of the surface plate cooling water can be 20 ° C.

(B2) Using the standard polishing composition, a silicon wafer test piece made of the same material as the silicon wafer to be polished is polished. For polishing the silicon wafer test piece, for example, a polishing machine PNX-332B manufactured by Okamoto Machinery Works, Inc. and a polishing pad POLYPAS27NX manufactured by Fujibo Co., Ltd. can be used. The polishing conditions for polishing the silicon wafer test piece are, for example, a polishing load of 15 kPa, a surface plate rotation speed of 30 rpm, a carrier rotation speed of 30 rpm, a polishing time of 2 min, a standard polishing composition supply speed of 2 L / min, and a standard polishing composition. The temperature of the object can be 20 ° C. and the temperature of the surface plate cooling water can be 20 ° C.

The standard polishing composition comprises 0.46% by mass of colloidal silica having an average primary particle diameter of 35 nm, 0.009% by mass of ammonia, 0.017% by mass of hydroxyethyl cellulose having a weight average molecular weight of 250,000, and polyethylene oxide and polypropylene oxide. It contains 0.002% by weight of the copolymer and the balance is water.

(B3) The haze h2 of the silicon wafer test piece polished in the b1 step and the haze α of the silicon wafer test piece polished in the b2 step are measured, and the finishing accuracy parameter P2 of the prepolishing composition is set based on the following formula. calculate.
Finishing accuracy parameter P2 = h2 / α × 100

2. 2. About the composition for finish polishing The composition for finish polishing used in the finish polishing process of a silicon wafer has a polishing processability parameter F1 obtained in the standard test 3 of 80 or less. The polishability parameter F1 is obtained in the standard test 3 in which the following c1 step, c2 step, and c3 step are performed in this order.

[Standard test 3]
(C1) The finish polishing composition is used to polish a silicon wafer test piece made of the same material as the silicon wafer to be polished. For polishing the silicon wafer test piece, for example, a polishing machine PNX-322 manufactured by Okamoto Machinery Works, Inc. and a polishing pad POLYPAS27NX manufactured by Fujibo Co., Ltd. can be used. The polishing conditions for polishing the silicon wafer test piece are, for example, a polishing load of 15 kPa, a surface plate rotation speed of 30 rpm, a carrier rotation speed of 30 rpm, a polishing time of 15 min, a finish polishing composition supply speed of 0.4 L / min, and finishing. The temperature of the polishing composition can be 20 ° C. and the temperature of the surface plate cooling water can be 20 ° C.

(C2) Using the standard polishing composition of Standard Test 2, a silicon wafer test piece made of the same material as the silicon wafer to be polished is polished. For polishing the silicon wafer test piece, for example, a polishing machine PNX-322 manufactured by Okamoto Machinery Works, Inc. and a polishing pad POLYPAS27NX manufactured by Fujibo Co., Ltd. can be used. The polishing conditions for polishing the silicon wafer test piece are, for example, a polishing load of 15 kPa, a surface plate rotation speed of 30 rpm, a carrier rotation speed of 30 rpm, a polishing time of 15 min, a standard polishing composition supply speed of 0.4 L / min, and a standard. The temperature of the polishing composition can be 20 ° C. and the temperature of the surface plate cooling water can be 20 ° C.

(C3) The polishing rate R of the polishing in the c1 step is calculated from the mass difference of the silicon wafer test pieces before and after the polishing in the c1 step, and the polishing in the c2 step is calculated from the mass difference of the silicon wafer test pieces before and after the polishing in the c2 step. The polishing rate β of is calculated. Then, the polishing processability parameter F1 of the finish polishing composition is calculated based on the following formula.
Polishing workability parameter F1 = R / β × 100

3. 3. Polishing Composition Set Since the polishing composition set of the present embodiment includes a pre-polishing composition and a finish polishing composition, it is used in a silicon wafer polishing method including two or more polishing steps. be able to. For example, it can be used as a polishing method for a silicon wafer having two polishing steps, a primary polishing step and a finish polishing step, which are preliminary polishing steps, and a primary polishing step and a secondary polishing step, which are preliminary polishing steps. It can also be used in a polishing method for a silicon wafer having three polishing steps, a finish polishing step and a finish polishing step.

When the polishing composition set of the present embodiment is used in the polishing method of a silicon wafer having three or more polishing steps, the finish polishing composition of the present embodiment is used in the finish polishing step, and the finish polishing composition of the present embodiment is used in the finish polishing step. The pre-polishing composition of the present embodiment is used in the pre-polishing step, which is the polishing step one step before, and the polishing composition suitable for the polishing step is appropriately selected for each of the other polishing steps. You can use it.

Next, the components constituting the finish polishing composition and the pre-polishing composition of the present embodiment will be described. The finish polishing composition and the pre-polishing composition of the present embodiment are both compositions containing abrasive grains, basic compounds, water-soluble polymers, and water. If desired, various additives may be contained.

4. Abrasive grains Abrasive grains have the function of physically polishing the surface of a silicon wafer. The type of abrasive grains is not particularly limited, but silica particles, alumina particles, cerium oxide particles, chromium oxide particles, titanium dioxide particles, zirconium oxide particles, magnesium oxide particles, manganese dioxide particles, zinc oxide particles, and red iron oxide particles. Oxide particles such as, silicon nitride particles, nitride particles such as boron nitride particles, carbide particles such as silicon carbide particles and boron carbide particles, carbonates such as calcium carbonate and barium carbonate, diamond particles and the like. Be done.

Among these specific examples, silica is preferable. Specific examples of silica include silica particles selected from colloidal silica, fumed silica, and sol-gel process silica. Among these silica particles, it is preferable to use silica particles selected from colloidal silica and fumed silica, particularly colloidal silica, from the viewpoint of reducing scratches generated on the surface to be polished of the silicon wafer. As the abrasive grains, one of these may be used alone, or two or more of them may be used in combination.

The average primary particle diameter of the abrasive grains used in the prepolishing composition is preferably 5 nm or more, more preferably 10 nm or more, still more preferably 15 nm or more, and particularly preferably 20 nm or more. By increasing the average primary particle size of the abrasive grains, the polishing speed of the silicon wafer is improved. The average primary particle diameter of the abrasive grains used in the pre-polishing composition is preferably 100 nm or less, more preferably 60 nm or less, still more preferably 50 nm or less. The smoothness of the surface to be polished is improved by reducing the average primary particle size of the abrasive grains.

The average primary particle size of the abrasive grains used in the finish polishing composition is preferably 5 nm or more, more preferably 10 nm or more. By increasing the average primary particle size of the abrasive grains, the polishing speed of the silicon wafer is improved. The average primary particle diameter of the abrasive grains used in the finish polishing composition is preferably 100 nm or less, more preferably 60 nm or less, still more preferably 50 nm or less, and particularly preferably 40 nm or less. The smoothness of the surface to be polished is improved by reducing the average primary particle size of the abrasive grains.

The value of the average primary particle diameter of the abrasive grains used in the pre-polishing composition and the finish-polishing composition can be calculated based on the specific surface area of the abrasive grains measured by the BET method. The specific surface area of the abrasive grains can be measured using, for example, the model "FlowSorbII 2300" manufactured by Micromeritex.

The average secondary particle diameter of the abrasive grains used in the prepolishing composition is preferably 10 nm or more, more preferably 20 nm or more, still more preferably 30 nm or more, and particularly preferably 40 nm or more. By increasing the average secondary particle size of the abrasive grains, the polishing speed of the silicon wafer is improved. The average secondary particle diameter of the abrasive grains used in the prepolishing composition is preferably 150 nm or less, more preferably 100 nm or less, still more preferably 80 nm or less, and particularly preferably 70 nm or less. The smoothness of the surface to be polished is improved by reducing the average secondary particle size of the abrasive grains.

The average secondary particle diameter of the abrasive grains used in the finish polishing composition is preferably 10 nm or more, more preferably 20 nm or more. By increasing the average secondary particle size of the abrasive grains, the polishing speed of the silicon wafer is improved. The average secondary particle diameter of the abrasive grains used in the finish polishing composition is preferably 100 nm or less, more preferably 80 nm or less, still more preferably 70 nm or less, and particularly preferably 60 nm or less. The smoothness of the surface to be polished is improved by reducing the average secondary particle size of the abrasive grains.
The value of the average secondary particle diameter of the abrasive grains used in the pre-polishing composition and the finish polishing composition can be measured by, for example, a dynamic light scattering method using UPA-UT151 manufactured by Nikkiso Co., Ltd. ..

The content of abrasive grains in the prepolishing composition is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and further preferably 0.10% by mass or more. When the content of abrasive grains is within the above range, the polishing speed of the silicon wafer is excellent.
The content of abrasive grains in the pre-polishing composition is preferably 3% by mass or less, more preferably 1% by mass or less, and further preferably 0.5% by mass or less. When the content of abrasive grains is within the above range, the dispersion stability of the prepolishing composition is improved.

The content of abrasive grains in the finish polishing composition is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and further preferably 0.10% by mass or more. When the content of abrasive grains is within the above range, the polishing speed of the silicon wafer is excellent.
The content of abrasive grains in the finish polishing composition is preferably 3% by mass or less, more preferably 1% by mass or less, still more preferably 0.5% by mass or less, and particularly preferably 0. It is 3% by mass or less. When the content of abrasive grains is within the above range, the dispersion stability of the finish polishing composition is improved.

5. Basic compounds The finish polishing composition and the pre-polishing composition contain a basic compound. The basic compound chemically polishes the surface to be polished of the silicon wafer by giving a chemical action (chemical etching). This makes it easy to improve the polishing speed when polishing the silicon wafer.

Specific examples of the basic compound include an inorganic basic compound, a hydroxide or salt of an alkali metal or an alkaline earth metal, a quaternary ammonium hydroxide or a salt thereof, ammonia, an amine and the like. Specific examples of alkali metals include potassium, sodium and the like. Specific examples of the salt include carbonates, bicarbonates, sulfates, acetates and the like. Specific examples of the quaternary ammonium include tetramethylammonium, tetraethylammonium, tetrabutylammonium and the like. Specific examples of the hydroxide or salt of the alkali metal include potassium hydroxide, potassium carbonate, potassium hydrogen carbonate, potassium sulfate, potassium acetate, potassium chloride 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, and piperazine anhydride. , Piperazine hexahydrate, 1- (2-aminoethyl) piperazine, N-methylpiperazine, guanidine, azoles such as imidazole and triazole, and the like. One of these basic compounds may be used alone, or two or more thereof may be used in combination.

Among the basic compounds, at least one selected from ammonia, ammonium salts, alkali metal hydroxides, alkali metal salts, and quaternary ammonium hydroxides is preferable. Among the basic compounds, select from ammonia, potassium hydroxide, sodium hydroxide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, ammonium hydrogencarbonate, ammonium carbonate, potassium hydrogencarbonate, potassium carbonate, sodium hydrogencarbonate, and sodium carbonate. At least one of them is more preferable. Among the basic compounds, at least one selected from ammonia, potassium hydroxide, sodium hydroxide, tetramethylammonium hydroxide, and tetraethylammonium hydroxide is more preferable, and even more preferably at least one of ammonia and tetramethylammonium hydroxide. And most preferably ammonia.

The content of the basic compound in the prepolishing composition is preferably 0.0001% by mass or more, more preferably 0.001% by mass or more, still more preferably 0.005% by mass or more. Particularly preferably, it is 0.01% by mass or more. Increasing the content of the basic compound in the pre-polishing composition tends to increase the polishing rate of the silicon wafer.

The content of the basic compound in the prepolishing composition is preferably 0.5% by mass or less, more preferably 0.1% by mass or less, and further preferably 0.05% by mass or less. The decrease in the content of the basic compound in the pre-polishing composition tends to improve the smoothness of the surface of the silicon wafer after polishing.

The content of the basic compound in the finish polishing composition is preferably 0.0001% by mass or more, more preferably 0.0005% by mass or more, and further preferably 0.001% by mass or more. As the content of the basic compound in the finish polishing composition increases, the polishing rate of the silicon wafer tends to increase.

The content of the basic compound in the composition for finish polishing is preferably 0.5% by mass or less, more preferably 0.1% by mass or less, still more preferably 0.05% by mass or less. Particularly preferably, it is 0.02% by mass or less. The decrease in the content of the basic compound in the finish polishing composition tends to improve the smoothness of the surface of the silicon wafer after polishing.

6. Water-soluble polymer The water-soluble polymer enhances the wettability of the surface to be polished of the silicon wafer during surface treatment of the silicon wafer such as during polishing and rinsing. The finish polishing composition and the pre-polishing composition are highly water-soluble solid raw materials that are put into water in a solid or solid state at the time of preparing the finish polishing composition and the pre-polishing composition as water-soluble polymers. Contains molecules.

The solid raw material means a raw material in a solid state or a solid state visually in an environment of a temperature of 23 ° C., a relative humidity of 50%, and 1 atm in the state of the raw material before being dissolved in water. In addition, some water-soluble polymers are synthesized from a monomer in water or a mixed solvent of water and an aqueous organic solvent such as alcohol or ketone, but the water-soluble polymer is in the form of an aqueous solution as it is in the solution state. Alternatively, it also includes an aqueous solution form in which a volatile solvent is distilled off. In the following, "water-soluble polymer of solid raw material", "water-soluble polymer in water-based form", and "water-soluble polymer in aqueous solution form" are simply referred to as "water-soluble polymer".

The water-soluble polymer has at least one functional group selected from a cationic group, an anionic group, and a nonionic group in the molecule, specifically, a hydroxyl group, a carboxy group, an acyloxy group, and a sulfo group in the molecule. , Amid group, amidino group, imino group, imide group, quaternary nitrogen structure, heterocyclic structure containing the functional group unit, vinyl structure, polyoxyalkylene structure and the like can be used.

Specific examples include cellulose derivatives, polyvinyl alcohol, poly (meth) acrylic acid, poly (meth) acrylamide alkyl sulfonic acid, polyisoprene sulfonic acid, polyvinyl sulfonic acid, polyallyl sulfonic acid, polyisoamylene sulfonic acid, and polystyrene sulfonic acid. Copolymers containing acid salt, poly (meth) acrylamide, polyalkylaminoalkyl (meth) acrylamide, polyvinylpyrrolidone, polyvinylpyrrolidone as part of the structure, polyvinylcaprolactam, copolymers containing polyvinylcaprolactam as part of the structure, Imine derivatives such as polyalkoxyalkyl (meth) acrylamide, polyhydroxyalkyl (meth) acrylamide, poly (meth) acrylic loylmorpholin, polyamidine, polyethyleneimine, hydrophilized polyimide, various polyamino acids, poly (N-acylalkyleneimine), etc. Polyvinyl alcohol derivatives in which a part of the hydroxyl group portion of polyvinyl alcohol is replaced with a quaternary nitrogen structure, polyoxyethylene, polymers having a polyoxyalkylene structure, diblock type, triblock type, random type, alternating type, etc. Examples thereof include polymers having a plurality of types of structures. The notation of poly (meth) acrylic acid means acrylic acid and / or methacrylic acid, and the same applies to other compounds.

Among water-soluble polymers, cellulose derivatives, polyvinyl alcohol, polyvinylpyrrolidone, and polyhydroxyalkyl (meth) are used from the viewpoints of improving the wettability of the surface to be polished of silicon wafers, suppressing the adhesion of particles, and reducing the surface roughness. ) Acrylamide, poly (meth) acrylic loylmorpholin, or a polymer having a polyoxyalkylene structure is suitable. Specific examples of the cellulose derivative include hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, ethyl cellulose, ethyl hydroxyethyl cellulose, carboxymethyl cellulose and the like.

Among the cellulose derivatives, hydroxyethyl cellulose is particularly preferable because it has a high ability to impart wettability to the surface to be polished of the silicon wafer and has good detergency. Further, as the water-soluble polymer, one type may be used alone, or two or more types may be used in combination.

The weight average molecular weight of the water-soluble polymer used in the prepolishing composition is preferably 10,000 or more, more preferably 20,000 or more, and further preferably 30,000 or more. As the weight average molecular weight of the water-soluble polymer increases, the polishing rate of the silicon wafer tends to increase.

The weight average molecular weight of the water-soluble polymer used in the prepolishing composition is preferably 2 million or less, more preferably 1.5 million or less, still more preferably 1.2 million or less, and even more preferably 1 million or less. It is particularly preferably 700,000 or less. By reducing the weight average molecular weight of the water-soluble polymer, the stability of the prepolishing composition tends to be more maintained. Further, the haze level of the surface to be polished of the silicon wafer tends to decrease.

The weight average molecular weight of the water-soluble polymer used in the finish polishing composition is preferably 10,000 or more, more preferably 20,000 or more, and further preferably 30,000 or more. As the weight average molecular weight of the water-soluble polymer increases, the polishing rate of the silicon wafer tends to increase.

The weight average molecular weight of the water-soluble polymer used in the finish polishing composition is preferably 2 million or less, more preferably 1.5 million or less, still more preferably 1.2 million or less, still more preferably 1 million or less. It is even more preferably 800,000 or less, particularly preferably 600,000 or less, and most preferably 300,000 or less. The decrease in the weight average molecular weight of the water-soluble polymer tends to maintain the stability of the finish polishing composition. Further, the haze level of the surface to be polished of the silicon wafer tends to decrease.

The content of the water-soluble polymer in the prepolishing composition is preferably 0.0001% by mass or more, more preferably 0.0005% by mass or more, and further preferably 0.001% by mass or more. .. As the content of the water-soluble polymer in the pre-polishing composition increases, the wettability of the surface to be polished of the silicon wafer tends to be further improved.

The content of the water-soluble polymer in the pre-polishing composition is preferably 0.5% by mass or less, more preferably 0.1% by mass or less, and further preferably 0.05% by mass or less. , More preferably 0.01% by mass or less, and particularly preferably 0.005% by mass or less. By reducing the content of the water-soluble polymer in the pre-polishing composition, the stability of the pre-polishing composition tends to be more maintained.

The content of the water-soluble polymer in the composition for finish polishing is preferably 0.0001% by mass or more, more preferably 0.0005% by mass or more, and further preferably 0.001% by mass or more. , Particularly preferably 0.005% by mass or more. Increasing the content of the water-soluble polymer in the finish polishing composition tends to further improve the wettability of the surface to be polished of the silicon wafer.

The content of the water-soluble polymer in the composition for finish polishing is preferably 0.5% by mass or less, more preferably 0.1% by mass or less, and further preferably 0.05% by mass or less. , More preferably 0.01% by mass or less. By reducing the content of the water-soluble polymer in the finish polishing composition, the stability of the finish polishing composition tends to be more maintained.

The mass ratio of the contents of abrasive grains, water-soluble polymer, and basic compound in the finish polishing composition and the prepolishing composition may be 50 to 99: 0.5 to 20: 0.5 to 30. Good. By setting the mass ratio of the contents in this range, the dispersion stability of the finish polishing composition and the pre-polishing composition is improved, and the cleanliness of the silicon wafer after cleaning is improved.

7. About the pH of the finish polishing composition and the pre-polishing composition The pH of the pre-polishing composition is not particularly limited, but is preferably 9.0 or more, more preferably 9.5 or more. More preferably, it is 10.0 or more. As the pH increases, the polishing rate of the silicon wafer tends to increase.
The pH of the prepolishing composition is preferably 11.5 or less, more preferably 11.0 or less, still more preferably 10.8 or less. As the pH decreases, the surface accuracy of the silicon wafer tends to improve.

The pH of the finish polishing composition is not particularly limited, but is preferably 9.0 or higher, more preferably 9.5 or higher, and even more preferably 9.8 or higher. As the pH increases, the polishing rate of the silicon wafer tends to increase.
The pH of the finish polishing composition is preferably 11.5 or less, more preferably 11.0 or less, still more preferably 10.5 or less. As the pH decreases, the surface accuracy of the silicon wafer tends to improve. The pH of the finish polishing composition and the pre-polishing composition can be adjusted, for example, by adding a pH adjuster described later.

8. Water Water serves as a dispersion medium or solvent for other components such as abrasive grains, basic compounds, and water-soluble polymers. For water, for example, the total content of transition metal ions should be 100 ppb or less in order to avoid hindering the action of other components contained in the finish polishing composition and the pre-polishing composition as much as possible. Is preferable. For example, the purity of water can be increased by removing impurities ions using an ion exchange resin, removing particles with a filter, distillation, and the like. Specifically, it is preferable to use ion-exchanged water, pure water, ultrapure water, distilled water and the like.

9. Additives The finish polishing composition and prepolishing composition of the present embodiment include various pH adjusters, surfactants, chelating agents, fungicides, etc., as necessary, in order to improve their performance. Additives may be added. However, it is preferable that the oxidizing agent is substantially not contained.

9-1 About pH adjuster The pH value of the finish polishing composition and the pre-polishing composition of the present embodiment can be adjusted by adding a pH adjuster. By adjusting the pH of the finish polishing composition and the pre-polishing composition, it is possible to control the polishing speed of the object to be polished, the dispersibility of the abrasive grains, and the like. The amount of the pH adjuster added is not particularly limited, and the final polishing composition and the pre-polishing composition may be appropriately adjusted to have a desired pH.

Specific examples of the pH adjuster include inorganic acids and organic acids such as carboxylic acids and organic sulfuric acids. Specific examples of the inorganic acid include hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, boric acid, carbonic acid, hypophosphorous acid, phosphorous acid, phosphoric acid and the like. Specific examples of the carboxylic acid include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, 2-methylbutyric acid, n-hexanoic acid, 3,3-dimethylbutyric acid, 2-ethylbutyric acid and 4-methylpentanoic acid. n-Heptanoic acid, 2-methylhexanoic acid, n-octanoic acid, 2-ethylhexanoic acid, benzoic acid, glycolic acid, salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid , Maleic acid, phthalic acid, malic acid, tartaric acid, citric acid, lactic acid, diglycolic acid, 2-furancarboxylic acid, 2,5-furancarboxylic acid, 3-furancarboxylic acid, 2-tetracarboxylic acid, methoxyacetic acid, Examples thereof include methoxyphenyl acetic acid and phenoxy acetic acid. Further, specific examples of organic sulfuric acid include methanesulfonic acid, ethanesulfonic acid, isethionic acid and the like. One of these acids may be used alone, or two or more of these acids may be used in combination.

9-2 Surfactant A surfactant may be added to the finish polishing composition and the pre-polishing composition of the present embodiment. Examples of the surfactant include anionic or nonionic surfactants, and among them, nonionic surfactants are preferable.

For example, oxyalkylene polymers such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl amine, polyoxyethylene fatty acid ester, and polyoxyethylene glyceryl ether. Polyoxyalkylene adducts such as fatty acid esters and polyoxyethylene sorbitan fatty acid esters, and nonionic surfactants such as copolymers of multiple types of oxyalkylenes (diblock type, triblock type, random type, alternating type). Can be mentioned.

Specific examples of the nonionic surfactant include a block copolymer of oxyethylene (EO) and oxypropylene (PO) (diblock body, PEO-PPO-PEO type triblock body, PPO-PEO-PPO type tri). (Block, etc.), Random copolymer of EO and PO, polyoxyethylene glycol, polyoxyethylene propyl ether, polyoxyethylene butyl ether, polyoxyethylene pentyl ether, polyoxyethylene hexyl ether, polyoxyethylene octyl ether, poly Oxyethylene-2-ethylhexyl ether, polyoxyethylene nonyl ether, polyoxyethylene decyl ether, polyoxyethylene isodecyl ether, polyoxyethylene tridecyl ether, polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl Ether, polyoxyethylene isostearyl ether, polyoxyethylene oleyl ether, polyoxyethylene phenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene nonylphenyl ether, polyoxyethylene dodecylphenyl ether, polyoxyethylene styrene phenyl ether, Polyoxyethylene laurylamine, polyoxyethylene stearylamine, polyoxyethylene oleylamine, polyoxyethylene stearylamide, polyoxyethylene oleylamide, polyoxyethylene monolauric acid ester, polyoxyethylene monostearic acid ester, polyoxyethylene distearic acid ester , Polyoxyethylene monooleic acid ester, polyoxyethylene dioleic acid ester, monolauric acid polyoxyethylene sorbitan, monopartimate polyoxyethylene sorbitan, monostearate polyoxyethylene sorbitan, monooleic acid polyoxyethylene sorbitan, triolein Examples thereof include polyoxyethylene sorbitan acid, polyoxyethylene sorbit tetraoleate, polyoxyethylene castor oil, and polyoxyethylene cured castor oil. Among these, preferred surfactants include block copolymers of EO and PO (particularly PEO-PPO-PEO type triblocks), random copolymers of EO and PO, and polyoxyethylene alkyl ethers (particularly, PEO-PPO-PEO type triblocks). For example, polyoxyethylene decyl ether).

Examples of the anionic surfactant include sulfuric acid ester and its salt of polyoxyethylene alkyl ether, sulfonic acid and its salt, carboxylic acid and its salt, and phosphoric acid ester and its salt.

Specific examples of anionic surfactants include polyoxyethylene lauryl ether sulfate, polyoxyethylene myristyl ether sulfuric acid, and polyoxyethylene palmityl ether sulfate; sodium polyoxyethylene lauryl ether sulfate, ammonium polyoxyethylene lauryl ether sulfate, and polyoxy. Ethylene lauryl ether sulfate triethanolamine, polyoxyethylene myristyl ether sulfate sodium, polyoxyethylene myristyl ether sulfate ammonium, polyoxyethylene myristyl ether sulfate triethanolamine, polyoxyethylene palmityl ether sulfate sodium, polyoxyethylene palmityl ether sulfate amine , Polyoxyethylene palmityl ether sulfate triethanolamine, polyoxyethylene octyl sulfonic acid, polyoxyethylene dodecyl sulfonic acid, polyoxyethylene cetyl sulfonic acid, polyoxyethylene octyl benzene sulfonic acid, polyoxyethylene dodecyl benzene sulfonic acid; Sodium oxyethylene octyl sulfonate, sodium polyoxyethylene dodecyl sulfonate, sodium polyoxyethylene cetyl sulfonate, polyoxyethylene lauryl ether acetic acid, polyoxyethylene tridecyl ether acetic acid, polyoxyethylene octyl ether acetic acid; polyoxyethylene lauryl ether Sodium acetate, polyoxyethylene lauryl ether ammonium acetate, polyoxyethylene tridecyl ether sodium acetate, polyoxyethylene tridecyl ether ammonium acetate, polyoxyethylene octyl ether sodium acetate, polyoxyethylene octyl ether ammonium acetate, polyoxyethylene lauryl ether Phosphate, polyoxyethylene alkyl (12-15) ether phosphate; sodium polyoxyethylene lauryl ether phosphate, sodium polyoxyethylene oleyl ether phosphate, sodium polyoxyethylene cetyl ether phosphate, polyoxyethylene alkyl (12-) 15) Potassium ether phosphate, disodium polyoxyethylene lauryl sulfosuccinate, disodium sulfosuccinate polyoxyethylene lauroyl ethanolamide disodium salt and the like can be mentioned.

The weight average molecular weight of the surfactant is preferably 200 or more, more preferably 250 or more, and even more preferably 300 or more. The increase in the weight average molecular weight of the surfactant improves the polishing rate of the silicon wafer.
The weight average molecular weight of the surfactant is preferably less than 10,000, more preferably 9500 or less. The smoothness of the surface to be polished is improved by reducing the weight average molecular weight of the surfactant.

9-3 Chelating agent A chelating agent may be added to the finish polishing composition and the pre-polishing composition of the present embodiment. The chelating agent suppresses metal contamination (particularly nickel and copper contamination) of the silicon substrate by capturing the metal impurity component in the polishing system and forming a complex.

Specific examples of the chelating agent include carboxylic acid chelating agents such as gluconic acid, amine chelating agents such as ethylenediamine, diethylenetriamine and trimethyltetraamine, ethylenediamine tetraacetic acid, nitrilotriacetic acid, hydroxyethylethylenediamine triacetic acid and triethylenetetramine-6. Polyaminopolycarboxylic acid chelating agents such as acetic acid and diethylenetriamine pentaacetic acid, 2-aminoethylphosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, aminotri (methylenephosphonic acid), ethylenediaminetetrax (methylenephosphonic acid), diethylenetriamine Organic phosphonic acid system such as penta (methylenephosphonic acid), ethane-1,1-diphosphonic acid, ethane-1,1,2-triphosphonic acid, methanehydroxyphosphonic acid, 1-phosphonobutane-2,3,4-tricarboxylic acid Examples thereof include a chelating agent, a phenol derivative, and 1,3-diketone. Among these chelating agents, organic phosphonic acid-based chelating agents, particularly ethylenediamine tetrakis (methylenephosphonic acid), are preferable. One of these chelating agents may be used alone, or two or more of these chelating agents may be used in combination.

9-4 Antifungal agent An antifungal agent may be added to the finish polishing composition and the prepolishing composition of the present embodiment. Specific examples of the fungicide include oxazolines such as oxazolidine-2,5-dione.

9-5 Oxidizing agent It is preferable that the finish polishing composition and the pre-polishing composition of the present embodiment substantially do not contain an oxidizing agent. When the finish polishing composition and the pre-polishing composition contain an oxidizing agent, the surface of the polishing target is oxidized by supplying the polishing composition to the polishing target (for example, a silicon wafer). This is because an oxide film is formed, which increases the required polishing time. Specific examples of the oxidizing agent referred to here include hydrogen peroxide (H ₂ O ₂ ), sodium persulfate, ammonium persulfate, potassium permanganate, sodium dichloroisocyanurate and the like.

The fact that the finish polishing composition and the pre-polishing composition do not substantially contain an oxidizing agent means that they do not contain an oxidizing agent at least intentionally. Therefore, the molar concentration of the oxidizing agent in the finish polishing composition and the pre-polishing composition is 0.0005 mol / L or less, preferably 0.0001 mol or less, due to the raw material, the manufacturing method, or the like. Polishing compositions (finish polishing composition, pre-polishing composition) inevitably containing an oxidizing agent of 0.00001 mol / L or less, particularly preferably 0.000001 mol / L or less. , Which can be included in the concept of a polishing composition which does not substantially contain an oxidizing agent.

10. About the polishing method of the silicon wafer The polishing of the silicon wafer using the finish polishing composition and the pre-polishing composition of the present embodiment can be performed by the polishing apparatus and polishing conditions used for ordinary polishing. For example, a single-sided polishing device or a double-sided polishing device can be used.

For example, when polishing a silicon wafer using a single-sided polishing device, the silicon wafer is held by a holder called a carrier, and a platen to which a polishing cloth is attached is pressed against one side of the silicon wafer to form the present embodiment. One side of the silicon wafer is polished by rotating the platen while supplying the finish polishing composition or the pre-polishing composition of.

When polishing a silicon wafer using a double-sided polishing device, the silicon wafer is held by a holder called a carrier, and a platen to which a polishing cloth is attached is applied from both sides of the silicon wafer to both sides of the silicon wafer. Both sides of the silicon wafer are polished by pressing each of them and rotating the platens on both sides while supplying the finish polishing composition or the pre-polishing composition of the present embodiment.

Regardless of which polishing device is used, the physical action due to friction (friction between the polishing cloth and the polishing composition (finish polishing composition, pre-polishing composition) and the silicon wafer) and the finish polishing composition. The silicon wafer is polished by the chemical action of the material and the pre-polishing composition on the silicon wafer.

As the polishing pad, various materials such as polyurethane, non-woven fabric, and suede can be used. Further, in addition to the difference in materials, materials having various physical properties such as hardness and thickness can be used. Further, both those containing abrasive grains and those containing no abrasive grains can be used, but those containing no abrasive grains are preferably used. Further, a liquid finish polishing composition and a grooved composition for collecting the pre-polishing composition can be used.

Further, in both the finish polishing step and the pre-polishing step, the polishing load (pressure applied to the silicon wafer) among the polishing conditions is not particularly limited, but may be 5 kPa or more and 50 kPa or less, preferably 8 kPa or more and 30 kPa or less. , More preferably 10 kPa or more and 20 kPa or less. When the polishing load is within this range, a sufficient polishing rate is exhibited, and it is possible to prevent the silicon wafer from being damaged by the load and from causing defects such as scratches on the surface of the silicon wafer.

Further, among the polishing conditions, the relative speed (linear speed) between the polishing pad used for polishing and the silicon wafer is not particularly limited, but may be 10 m / min or more and 300 m / min or less, preferably 30 m / min or more and 200 m / min. Less than a minute. If the relative speed between the polishing pad and the silicon wafer is within this range, a sufficient polishing speed can be obtained. Further, the damage of the polishing pad due to the friction of the silicon wafer can be suppressed, the friction is sufficiently transmitted to the silicon wafer, the so-called slipping state of the silicon wafer can be suppressed, and the polishing can be sufficiently performed.

Further, among the polishing conditions, the supply amount of the finish polishing composition and the pre-polishing composition varies depending on the type of the silicon wafer, the type of the polishing device, and the polishing conditions, but finishes between the silicon wafer and the polishing cloth. The amount of the polishing composition and the pre-polishing composition may be sufficient to be uniformly supplied to the entire surface. When the supply amount of the finish polishing composition and the pre-polishing composition is small, the finish polishing composition and the pre-polishing composition are not supplied to the entire silicon wafer, and the finish polishing composition and the pre-polishing composition are not supplied. The material may dry and solidify, causing defects on the surface of the silicon wafer. On the contrary, when the supply amount of the finish polishing composition and the pre-polishing composition is large, it is not economical and friction is hindered by the excessive finish polishing composition and the pre-polishing composition (particularly water). There is a risk that polishing will be hindered.

Further, the finish polishing composition and the pre-polishing composition of the present embodiment can be recovered after being used for polishing a silicon wafer and reused for polishing a silicon wafer. As an example of the method of reusing the finish polishing composition and the pre-polishing composition, the finish polishing composition and the pre-polishing composition discharged from the polishing apparatus are collected in a tank and circulated in the polishing apparatus again. There is a method of making it used for polishing. If the finish polishing composition and the pre-polishing composition are recycled, the amount of the finish polishing composition and the pre-polishing composition discharged as waste liquid can be reduced, so that the environmental load can be reduced. .. Further, since the amount of the finish polishing composition and the pre-polishing composition used can be reduced, the manufacturing cost required for polishing the silicon wafer can be suppressed.

When the finish polishing composition and the pre-polishing composition of the present embodiment are reused, abrasive grains, water-soluble polymers, basic compounds, additives, etc. consumed or lost due to the use in polishing are used. Part or all of it may be added as a composition regulator and then reused. As the composition adjuster, a mixture of abrasive grains, a water-soluble polymer, a basic compound, an additive and the like at an arbitrary mixing ratio can be used. By adding the composition adjusting agent additionally, the composition for finish polishing and the composition for pre-polishing can be adjusted to a composition suitable for reuse, and suitable polishing can be performed. The concentrations of the abrasive grains, the water-soluble polymer, the basic compound, and other additives contained in the composition adjuster are arbitrary and are not particularly limited, and may be appropriately adjusted according to the size of the tank and the polishing conditions. ..

It should be noted that the present embodiment shows an example of the present invention, and the present invention is not limited to the present embodiment. In addition, various changes or improvements can be added to the present embodiment, and the modified or improved forms may be included in the present invention. For example, the finish polishing composition and the pre-polishing composition of the present embodiment may be a one-component type, and some or all of the components of the finish polishing composition and the pre-polishing composition may be arbitrary. It may be a multi-component type such as a two-component type mixed in a ratio. Further, in polishing a silicon wafer, the finish polishing composition and the undiluted solution of the pre-polishing composition of the present embodiment may be used as they are for polishing, but the undiluted solution may be diluted with water or the like 10 times or more, for example. Polishing may be performed using a diluted finish polishing composition or a diluted prepolishing composition.

〔Example〕
Examples and comparative examples are shown below, and the present invention will be described in more detail with reference to Tables 1 and 2.
A pretreatment composition obtained by mixing abrasive grains made of colloidal silica having an average primary particle diameter of 12 nm, 25 nm, or 35 nm, a basic compound, a water-soluble polymer, a surfactant, and pure water. Standard polishing compositions, pre-polishing compositions a, b, c, d, h, and finish polishing compositions e, f, g, i were produced. The contents of abrasive grains, basic compounds, water-soluble polymers, and surfactants in each composition are as shown in Table 1, and the balance is pure water.

The type of basic compound used is ammonia (NH ₃ ) or potassium hydroxide (KOH). The types of water-soluble polymers used and the weight average molecular weights are as shown in Table 1. In addition, "HEC" in Table 1 means hydroxyethyl cellulose, and "PVP" means polyvinylpyrrolidone. Further, the surfactant used is a block copolymer (PEO-PPO) composed of ethylene oxide (EO) and propylene oxide (PO), or a polyoxyethylene decyl ether (C-PEO).

Next, the hydrophilicity parameter P1 and the finish accuracy parameter P2 of the pre-polishing compositions a, b, c, d, and h, and the polishability parameter F1 of the finish-polishing compositions e, f, g, and i were obtained. .. The results are shown in Table 2.

The contents of the standard test 1 for obtaining the hydrophilicity parameter P1, the standard test 2 for obtaining the finish accuracy parameter P2, and the standard test 3 for obtaining the polishability parameter F1 will be described below. The materials of the test pieces used to obtain each parameter in the standard tests 1, 2 and 3 are the pre-polishing compositions a, b, c, d and h and the finish-polishing compositions e, f and g. It is made of the same material as the silicon wafer, which is the object to be polished to be polished using i.

Further, in the standard tests 1, 2 and 3, the test piece or its material for obtaining each parameter is not the same material as the silicon wafer to be polished, but silicon of the same material as the silicon wafer to be polished. A wafer is used, but it goes without saying that the same silicon wafer as the object to be polished may be used as a test piece.

The hydrophilicity parameter P1 is obtained in the standard test 1 in which the following steps X1 to X6 are performed in this order.
[Standard test 1]
(X1) Pretreatment is performed on a silicon wafer of the same material as the silicon wafer to be polished (in this embodiment, a silicon wafer having a diameter of 300 mm, a conductive P type, a crystal orientation <100>, and no crystal defects). Give. That is, the silicon wafer is polished using the pretreatment composition, then polished using the standard polishing composition, and further washed and dried.

The cleaning was carried out using a cleaning solution in which ammonia water having a concentration of 29% by mass, hydrogen peroxide solution having a concentration of 31% by mass, and deionized water (DIW) were mixed at a volume ratio of 1: 3:30. More specifically, two cleaning tanks equipped with an ultrasonic oscillator having a frequency of 950 kHz were prepared, and the cleaning liquid was contained in each of the first and second cleaning tanks and kept at 60 ° C. Then, the polished silicon wafer is immersed in the first cleaning tank with the ultrasonic oscillator operated for 6 minutes, and then immersed in the rinse tank containing ultrapure water with the ultrasonic oscillator operated. Rinse and then immerse in a second washing tank for 6 minutes with the ultrasonic oscillator operating. Hereinafter, such a cleaning step will be referred to as SC-1 cleaning.

For polishing using the pretreatment composition, a polishing machine PNX-332B manufactured by Okamoto Koki Seisakusho Co., Ltd. and a polishing pad FP55 manufactured by Fujibo Co., Ltd. are used, and the polishing conditions are a polishing load of 20 kPa and surface plate rotation. The speed is 20 rpm, the carrier rotation speed is 20 rpm, the polishing time is 2 min, the supply speed of the pretreatment composition is 1 L / min, the temperature of the pretreatment composition is 20 ° C., and the temperature of the surface plate cooling water is 20 ° C.

Further, for polishing using the standard polishing composition, a polishing machine PNX-332B manufactured by Okamoto Koki Seisakusho Co., Ltd. and a polishing pad POLYPAS27NX manufactured by Fujibo Co., Ltd. are used, and the polishing conditions are a polishing load of 15 kPa. The plate rotation speed is 30 rpm, the carrier rotation speed is 30 rpm, the polishing time is 2 min, the supply speed of the standard polishing composition is 2 L / min, the temperature of the standard polishing composition is 20 ° C., and the temperature of the surface plate cooling water is 20 ° C.

The pretreatment composition contains 0.95% by mass of colloidal silica and 0.065% by mass of potassium hydroxide having an average primary particle diameter of 35 nm, and the balance is pure water.
The standard polishing composition comprises 0.46% by mass of copolymer silica having an average primary particle size of 35 nm, 0.009% by mass of ammonia, 0.017% by mass of hydroxyethyl cellulose having a weight average molecular weight of 250,000, and polyethylene oxide and polypropylene oxide. It contains 0.002% by mass of the copolymer, and the balance is pure water.

(X2) The pretreated silicon wafer is cut to prepare a square silicon chip test piece having a side length of 60 mm. This silicon chip test piece is immersed in a hydrogen fluoride aqueous solution having a concentration of 3% by mass, and then washed with pure water.

(X3) Using the pre-polishing composition, the silicon chip test piece washed with pure water in the X2 step is polished. A tabletop polishing machine EJ-380IN manufactured by Nippon Engis Co., Ltd. and a polishing pad POLYPAS27NX manufactured by Fujibo Co., Ltd. are used for polishing this silicon chip test piece, and the polishing conditions are a polishing load of 16 kPa, a surface plate rotation speed of 30 rpm, and so on. The carrier rotation speed is 30 rpm, the polishing time is 2 min, the supply speed of the pre-polishing composition is 30 mL / min, and the temperature of the pre-polishing composition is 20 ° C.

(X4) The surface of the silicon chip test piece polished in the X3 step is washed with pure water to wash away the pre-polishing composition.
(X5) The silicon chip test piece washed with pure water in the X4 step is allowed to stand for 30 seconds in a posture in which one diagonal line of the silicon chip test piece is along the vertical direction, and the surface of the silicon chip test piece is exposed on the diagonal line. The length of the region not wet with pure water is measured, and the length is defined as the water repellent distance.

(X6) From the measured water repellency distance, the hydrophilicity parameter P1 of the prepolishing composition is calculated based on the following formula.
Hydrophilic parameter P1 = {(diagonal length of silicon chip test piece [mm])-(water repellent distance [mm])} / (diagonal length of silicon chip [mm]) × 100
The finishing accuracy parameter P2 is obtained in the standard test 2 in which the following steps Y1 to Y5 are performed in this order.

[Standard test 2]
(Y1) For a silicon wafer test piece made of the same material as the silicon wafer to be polished (in this example, a silicon wafer test piece having a diameter of 300 mm, a conduction type P type, a crystal orientation <100>, and no crystal defects). , Pretreatment is performed in the same manner as the X1 step of the standard test 1. That is, the silicon wafer test piece is polished using the pretreatment composition, then polished using the standard polishing composition, and further subjected to the pretreatment for SC-1 cleaning and drying.

(Y2) The silicon wafer test piece pretreated in the Y1 step is re-polished using the pretreatment composition. For this polishing, a polishing machine PNX-332B manufactured by Okamoto Koki Seisakusho Co., Ltd. and a polishing pad FP55 manufactured by Fujibo Co., Ltd. are used, and the polishing conditions are a polishing load of 20 kPa, a surface plate rotation speed of 20 rpm, and a carrier rotation speed of 20 rpm. The polishing time is 2 min, the supply speed of the pretreatment composition is 1 L / min, the temperature of the pretreatment composition is 20 ° C., and the temperature of the surface plate cooling water is 20 ° C.

(Y3) The pre-polishing composition is used to polish the silicon wafer test piece polished in the Y2 step. A polishing machine PNX-332B manufactured by Okamoto Machinery Works, Inc. and a polishing pad POLYPAS27NX manufactured by Fujibo Co., Ltd. are used for polishing the silicon wafer test piece. The polishing conditions for polishing the silicon wafer test piece are: polishing load 15 kPa, surface plate rotation speed 30 rpm, carrier rotation speed 30 rpm, polishing time 2 min, pre-polishing composition supply speed 2 L / min, pre-polishing composition. The temperature is 20 ° C. and the temperature of the surface plate cooling water is 20 ° C.

(Y4) The standard polishing composition is used to polish the silicon wafer test piece that has been polished in the Y2 step. A polishing machine PNX-332B manufactured by Okamoto Machinery Works, Inc. and a polishing pad POLYPAS27NX manufactured by Fujibo Co., Ltd. are used for polishing the silicon wafer test piece. The polishing conditions for polishing the silicon wafer test piece are a polishing load of 15 kPa, a surface plate rotation speed of 30 rpm, a carrier rotation speed of 30 rpm, a polishing time of 2 min, a standard polishing composition supply speed of 2 L / min, and a standard polishing composition. The temperature is 20 ° C. and the temperature of the surface plate cooling water is 20 ° C.

(Y5) After SC-1 cleaning and drying of the silicon wafer test piece polished in the Y3 step and the silicon wafer test piece polished in the Y4 step, respectively, a surface foreign matter inspection device SURFSCAN SP2 manufactured by KLA Tencor Co., Ltd. is used. Then, the haze on the surface of each silicon wafer test piece is measured in the DWO mode. From the haze h2 of the silicon wafer test piece polished in the Y3 step and the haze α of the silicon wafer test piece polished in the Y4 step, the finishing accuracy parameter P2 of the pre-polishing composition is calculated based on the following formula.
Finishing accuracy parameter P2 = h2 / α × 100

The polishability parameter F1 is obtained in the standard test 3 in which the following steps Z1 to Z6 are performed in this order.
[Standard test 3]
(Z1) For a silicon wafer test piece made of the same material as the silicon wafer to be polished (in this example, a silicon wafer test piece having a diameter of 200 mm, a conductive P type, a crystal orientation <100>, and no crystal defects). , Pre-treat. That is, the silicon wafer test piece is polished using the pretreatment composition, then polished using the standard polishing composition, and further SC-1 cleaning and drying are performed.

For polishing using the pretreatment composition, a polishing machine PNX-322 manufactured by Okamoto Koki Seisakusho Co., Ltd. and a polishing pad FP55 manufactured by Fujibo Co., Ltd. are used, and the polishing conditions are a polishing load of 15 kPa and surface plate rotation. The speed is 30 rpm, the carrier rotation speed is 30 rpm, the polishing time is 3 min, the supply speed of the pretreatment composition is 0.55 L / min, the temperature of the pretreatment composition is 20 ° C., and the temperature of the surface plate cooling water is 20 ° C.

Further, for polishing using the standard polishing composition, a polishing machine PNX-322 manufactured by Okamoto Koki Seisakusho Co., Ltd. and a polishing pad POLYPAS27NX manufactured by Fujibo Co., Ltd. are used, and the polishing conditions are a polishing load of 15 kPa. The plate rotation speed is 30 rpm, the carrier rotation speed is 30 rpm, the polishing time is 4 min, the supply speed of the standard polishing composition is 0.4 L / min, the temperature of the standard polishing composition is 20 ° C., and the temperature of the surface plate cooling water is 20 ° C.

(Z2) The mass of the silicon wafer test piece pretreated in the Z1 step is measured. Then, the silicon wafer test piece is immersed in a hydrogen fluoride aqueous solution having a concentration of 3% by mass, and then washed with pure water.

(Z3) The silicon wafer test piece washed with pure water in the Z2 step is polished using the finish polishing composition. A polishing machine PNX-322 manufactured by Okamoto Machinery Works, Inc. and a polishing pad POLYPAS27NX manufactured by Fujibo Co., Ltd. are used for polishing the silicon wafer test piece. The polishing conditions for polishing the silicon wafer test piece are: polishing load 15 kPa, surface plate rotation speed 30 rpm, carrier rotation speed 30 rpm, polishing time 15 min, supply speed 0.4 L / min of finish polishing composition, finish polishing. The temperature of the composition is 20 ° C., and the temperature of the surface plate cooling water is 20 ° C.

(Z4) The silicon wafer test piece washed with pure water in the Z2 step is polished using the standard polishing composition. A polishing machine PNX-322 manufactured by Okamoto Machinery Works, Inc. and a polishing pad POLYPAS27NX manufactured by Fujibo Co., Ltd. are used for polishing the silicon wafer test piece. The polishing conditions for polishing this silicon wafer test piece are: polishing load 15 kPa, surface plate rotation speed 30 rpm, carrier rotation speed 30 rpm, polishing time 15 min, supply speed 0.4 L / min of standard polishing composition, for standard polishing. The temperature of the composition is 20 ° C., and the temperature of the surface plate cooling water is 20 ° C.

(Z5) The mass of the silicon wafer test piece polished in the Z3 step and the silicon wafer test piece polished in the Z4 step are measured after SC-1 cleaning and drying, respectively.
(Z6) From the difference between the mass of the silicon wafer test piece measured in the Z2 process and the mass of the silicon wafer test piece measured in the Z5 process, the polishing rate R for polishing in the Z3 process and the polishing rate β for polishing in the Z4 process are determined. Calculate each. Then, the polishing processability parameter F1 of the finish polishing composition is calculated based on the following formula.
Polishing workability parameter F1 = R / β × 100

Such pre-polishing compositions a, b, c, d, h and finish polishing compositions e, f, g, i are appropriately combined in Examples 1 , Reference Examples 1 to 3 and Comparative Examples 1 to 1. A polishing composition set of No. 4 was prepared (see Table 2). Then, the silicon wafer, which is the object to be polished, was polished using these polishing composition sets, and the haze of the surface of the silicon wafer after polishing was measured. The polishing method of the silicon wafer includes a primary polishing step of polishing using the pretreatment composition, a pre-polishing step (secondary polishing step) of polishing using the pre-polishing composition, and finish polishing. The method includes a finish polishing step of polishing using the composition for use.

A method for polishing a silicon wafer and a method for measuring haze will be specifically described.
(1) First, a silicon wafer having a diameter of 300 mm, a conduction type P type, a crystal orientation <100>, and no crystal defects is pretreated in the same manner as in the X1 step of the standard test 1. That is, the silicon wafer is polished using the pretreatment composition, then polished using the standard polishing composition, and further subjected to the pretreatment for SC-1 cleaning and drying.

(2) Subsequently, the silicon wafer subjected to the pretreatment in the step (1) is re-polished using the pretreatment composition. The polishing apparatus and polishing pad used when polishing the silicon wafer are the same as in the Y2 step of the standard test 2. Further, the polishing conditions for polishing the silicon wafer are the same as in the Y2 step of the standard test 2.

(3) Next, the pre-polishing composition of the polishing composition set is used to further polish the silicon wafer re-polished using the pre-treatment composition in the step (2). The polishing apparatus and polishing pad used when polishing the silicon wafer are the same as in the Y3 step of the standard test 2. Further, the polishing conditions for polishing the silicon wafer are the same as in the Y3 step of the standard test 2.

(4) Further, the silicon wafer polished by using the pre-polishing composition in the step (3) is further polished by using the finish polishing composition of the polishing composition set. The polishing apparatus and polishing pad used when polishing the silicon wafer are the same as in the Y3 step of the standard test 2. Further, the polishing conditions for polishing the silicon wafer are the same as in the Y3 step of the standard test 2.

(5) Then, after SC-1 cleaning and drying of the silicon wafer polished using the finish polishing composition in the step (4), a surface foreign matter inspection device SURFSCAN SP2 manufactured by KLA Tencor Co., Ltd. is used. It is used to measure the haze of the surface of a silicon wafer in DWO mode.

Table 2 shows the measurement results of haze. The silicon wafers polished using the polishing composition sets of Examples 1 and Reference Examples 1 to 3 have a hydrophilicity parameter P1 of the pre-polishing composition of less than 100 and a finishing accuracy parameter P2 of the pre-polishing composition. Is 1000 or less, and the polishability parameter F1 of the finish polishing composition is 80 or less, so that the haze of the surface of the silicon wafer after finish polishing is low and a high-quality surface to be polished is obtained.

On the other hand, the silicon wafer polished by using the polishing composition sets of Comparative Examples 1 to 4 has the hydrophilicity parameter P1 of the pre-polishing composition, the finishing accuracy parameter P2 of the pre-polishing composition, and the finishing. Since any of the polishing processability parameters F1 of the polishing composition did not meet the required requirements, the haze on the surface of the silicon wafer after finish polishing was high.

Claims (5)

It comprises a finish polishing composition used in a finish polishing step of performing finish polishing of a silicon wafer, and a pre-polishing composition used in a pre-polishing step which is a polishing step one step before the finish polishing step. A set of polishing compositions
The hydrophilicity parameter P1 of the pre-polishing composition obtained in the standard test 1 in which the following a1 step, a2 step, a3 step, and a4 step are performed in this order is less than 100, and the following b1 step, b2 step, and b3 The finishing accuracy parameter P2 of the pre-polishing composition obtained in the standard test 2 in which the steps are performed in this order is 1000 or less , and the finishing obtained in the standard test 3 in which the following c1 step, c2 step, and c3 step are performed in this order. A polishing composition set in which the polishing processability parameter F1 of the polishing composition is 45 or less.
[Standard test 1]
(A1) Using the pre-polishing composition, a silicon test piece of the same material as the silicon wafer to be polished is polished. The silicon test piece is a circular wafer or a chip cut into a quadrangle.
(A2) The polished surface of the silicon test piece is washed with pure water to wash away the pre-polishing composition.
(A3) The silicon test piece washed with pure water is arranged so that the diameter of the silicon test piece is along the vertical direction when the silicon test piece is circular, and one diagonal line is in the vertical direction when the silicon test piece is square. Let stand for 30 seconds in a posture along the above, measure the length of the region of the diameter or diagonal where the surface of the silicon test piece is not wet with pure water, and use that length as the water repellent distance.
(A4) From the measured water repellency distance, the hydrophilicity parameter P1 of the prepolishing composition is calculated based on the following formula.
Hydrophilic parameter P1 = {(diameter of silicon test piece or diagonal length [mm])-(water repellent distance [mm])} / (diameter of silicon test piece or diagonal length [mm]) × 100
[Standard test 2]
(B1) Using the pre-polishing composition, a silicon wafer test piece made of the same material as the silicon wafer to be polished is polished.
(B2) Using the standard polishing composition, a silicon wafer test piece made of the same material as the silicon wafer to be polished is polished.
The standard polishing composition is composed of 0.46% by mass of colloidal silica having an average primary particle diameter of 35 nm, 0.009% by mass of ammonia, 0.017% by mass of hydroxyethyl cellulose having a weight average molecular weight of 250,000, and polyethylene oxide and polypropylene oxide. It contains 0.002% by mass of the copolymer, and the balance is water.
(B3) The haze h2 of the silicon wafer test piece polished in the b1 step and the haze α of the silicon wafer test piece polished in the b2 step were measured, and the finishing accuracy parameter P2 of the prepolishing composition was measured based on the following formula. Is calculated.
Finishing accuracy parameter P2 = h2 / α × 100
[Standard test 3]
(C1) Using the finish polishing composition, a silicon wafer test piece made of the same material as the silicon wafer to be polished is polished.
(C2) Using the standard polishing composition of Standard Test 2, a silicon wafer test piece made of the same material as the silicon wafer to be polished is polished.
(C3) The polishing rate R of the polishing in the c1 step is calculated from the mass difference of the silicon wafer test piece before and after the polishing in the c1 step, and the c2 step is calculated from the mass difference of the silicon wafer test piece before and after the polishing in the c2 step. Calculate the polishing rate β of the polishing of. Then, the polishing processability parameter F1 of the finish polishing composition is calculated based on the following formula.
Polishing workability parameter F1 = R / β × 100 The polishing composition set according to claim 1, wherein both the finish polishing composition and the pre-polishing composition are compositions containing abrasive grains, a basic compound, and a water-soluble polymer. The method for polishing a silicon wafer, comprising a finish polishing step of performing finish polishing of the silicon wafer and a pre-polishing step which is a polishing step one step before the finish polishing step, according to claim 1 or 2. A method for polishing a silicon wafer in which the finish polishing step and the pre-polishing step are performed using the polishing composition set of. The composition for finish polishing used in the finish polishing step of the method for polishing a silicon wafer, which comprises a finish polishing step of performing finish polishing of a silicon wafer and a pre-polishing step which is a polishing step one step before the finish polishing step. It ’s a thing,
A composition for finish polishing in which the polishing processability parameter F1 obtained in the standard test 3 in which the following c1 step, c2 step, and c3 step are performed in this order is 45 or less.
[Standard test 3]
(C1) Using the finish polishing composition, a silicon wafer test piece made of the same material as the silicon wafer to be polished is polished.
(C2) The standard polishing composition is used to polish a silicon wafer test piece made of the same material as the silicon wafer to be polished.
The standard polishing composition is composed of 0.46% by mass of colloidal silica having an average primary particle diameter of 35 nm, 0.009% by mass of ammonia, 0.017% by mass of hydroxyethyl cellulose having a weight average molecular weight of 250,000, and polyethylene oxide and polypropylene oxide. It contains 0.002% by mass of the copolymer, and the balance is water.
(C3) The polishing rate R of the polishing in the c1 step is calculated from the mass difference of the silicon wafer test piece before and after the polishing in the c1 step, and the c2 step is calculated from the mass difference of the silicon wafer test piece before and after the polishing in the c2 step. Calculate the polishing rate β of the polishing of. Then, the polishing processability parameter F1 of the finish polishing composition is calculated based on the following formula.
Polishing workability parameter F1 = R / β × 100 The composition for finish polishing according to claim 4 , which contains abrasive grains, a basic compound, and a water-soluble polymer.