JP2003041240A - Cutting grain, cutting composition containing the same, and method for producing silicon wafer using the composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fine silicon carbide powder for cutting a hard and brittle material which enables to achieve a high cutting speed and an excellent cutting accuracy; a cutting composition comprising the same; a stable method for producing a silicon wafer using the composition. SOLUTION: The silicon carbide powder comprises having a grain distribution width of 0.9 or less and (1) a lap speed against glass material of [D(50%)-0.5]-[4.3×D(50%)+0.8], (2) a bulk specific gravity of 1.75 g/mL as measured in water or (3) a grain aspect ratio of 0.59 or more. The cutting composition comprises the powder. The method for producing a silicon wafer comprises using the composition to cut a silicon ingot by a wire saw.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to cutting abrasive grains and a cutting composition used for cutting hard and brittle materials. More specifically, the present invention relates to a cutting abrasive grain and a cutting composition used when cutting a semiconductor material, a metal oxide, a ferrite, a glass material, and a hard and brittle material such as quartz crystal with a cutting device such as a wire saw. It is a thing. The present invention also relates to a method for producing a silicon wafer by cutting a silicon ingot with a wire saw using the above-mentioned abrasive grains for cutting or the composition for cutting.

[0002]

2. Description of the Related Art In recent years, high-performance semiconductor device chips used in high-tech products such as computers are becoming more highly integrated, and as a result, the chip size is becoming larger. And with the increase of this chip size, productivity decline, cost increase,
And other problems are occurring.

The reasons for the decrease in productivity and the increase in cost due to the increase in size of device chips are as follows. Generally, a semiconductor chip is manufactured by cutting an ingot into various pieces by a cutting device to form a wafer, forming a desired wiring circuit on the wafer by a photoresist technique, and cutting the wafer into a single chip.
As the performance of semiconductor devices becomes higher, the wiring patterns become more complicated, and if the size of the original wafer does not change, the number of chips that can be cut out from one wafer will decrease, The area of the remaining portion after cutting, especially the portion where the chips cannot be taken near the outer periphery of the wafer becomes large. Therefore, the number of chips per unit area that can be cut out from the original wafer is reduced, the yield is reduced, and the productivity is reduced and the cost is increased.

Therefore, these problems have been solved by increasing the area of the original wafer and increasing the number of chips per unit area.

Up to now, an inner peripheral blade type cutting device has been used for cutting a silicon ingot having a relatively small area, for example, up to a diameter of about 6 inches. This is largely because the inner peripheral blade type cutting device has high processing accuracy and excellent productivity in cutting an ingot having a relatively small diameter because the “blur” of the cutting blade is relatively small.

However, when an ingot having a large diameter is to be cut by using an inner peripheral blade type cutting device, the deviation of the cutting blade at the time of cutting becomes large, and the center portion of the wafer becomes convex. Is likely to occur. As a result, the processing accuracy deteriorates, and the yield of wafers decreases.

In order to solve this problem, a large diameter,
For example, a wire saw is often used to cut an ingot having a diameter of 8 inches or more. Compared with other methods, this wire saw can cut ingots with a more uniform thickness, and less cutting waste called kerfloss is generated, so it is possible to cut many wafers at once. There is an advantage called.

The cutting of the various ingots described above is carried out for the purpose of lubrication and cooling during processing, or for the purpose of improving the shape of the cut wafer and the smoothness of the cut surface.
A cutting composition in which an abrasive is dispersed in a cutting liquid is used. Conventionally, the cutting composition that has been used in various cutting devices such as an inner peripheral blade and a wire saw can be roughly classified into a glycol type, an oil type, and a water type, depending on the difference in the working fluid that constitutes the cutting composition. it can.

The abrasive grains in the cutting composition are generally used for precision lapping of silicon, glass, crystal, ferrite, etc., and for surface treatment of cemented carbide, soft metal, stone, resin, etc. The conventional abrasive grains such as silicon carbide fine powder and aluminum oxide fine powder have been diverted as they are.

These conventional fine powders are designed to have a particle shape and particle size distribution optimized for their original use.
For this reason, when it is used for a cutting purpose other than the original purpose, the machining accuracy of the machined surface, specifically TTV, Warp,
There was room for improvement in terms of.

Here, TTV (Total Thickness Variati
on) is a parameter that represents the flatness of the wafer surface, and determines the reference surface by fixing one side of the wafer to a completely flat state by chucking or the like.
Measure the height from the reference surface on the entire wafer,
It represents the distance from the maximum height to the minimum height.

Warp is a parameter representing the waviness of the wafer, and represents the difference between the maximum displacement and the minimum displacement of the wafer center plane from the three-point reference plane or the best-fit reference plane on the back surface of the wafer. is there.

As means for solving the above-mentioned problems, many proposals have heretofore been made regarding improvement of cutting conditions and a cutting apparatus, and change of composition of a cutting working fluid constituting a cutting composition. However, as far as the present inventors are aware, no improvement measures have been proposed regarding the cutting abrasive grains themselves. Further, according to the study by the present inventors, it is difficult to obtain stable processing accuracy in any of the improvement of the cutting conditions and the cutting device, and the change of the composition of the cutting processing liquid constituting the cutting composition. I understood.

Further, as the price of computers and the like has been reduced, the cost of semiconductor device devices has also been required to be reduced, and the yield is also improved in the cutting process of silicon ingot which is one of the manufacturing processes of silicon wafers. It is necessary to reduce the cost. Therefore, there has been a demand for a cutting composition that can stably achieve excellent processing accuracy while maintaining a high cutting speed.

[0015]

The silicon carbide fine powder for cutting abrasive grains according to the first aspect of the present invention is a silicon carbide fine powder for cutting abrasive grains for cutting a hard and brittle material, which comprises: )
The particle size distribution width calculated by the formula is 0.9 or less, and the lapping speed with respect to the glass material is within the range of the formula (2) below. Particle size distribution width = [D (3%)-D (94%)] / D (50%) (1) ｜ [D (50%)-0.5] ｜ ≦ ｜ Lapping speed for glass material ｜ ≦ ｜ [4.3 × D (50%) + 0.8] | (2) where D (3%), D (50%), and D (94%) are the cumulative particle volumes from the large particle size side of the total particle volume. 3% and 5 respectively
The particle size reaches 0% and 94%. Also, (2)
In the formula, D (50%) and the lapping speed with respect to the glass material are numerical values expressed in units of μm and μm / min, respectively, and the lapping speed with respect to the glass material is the following lapping conditions using the silicon carbide fine powder. It is calculated from the amount of decrease in the thickness of the glass material when lapping is performed. Lapping machine: 4BT (manufactured by Hamai Seisakusho Co., Ltd.) Surface plate: Lattice-shaped grooved cast iron surface plate (groove width 2 mm, groove cutting pitch 15 m
m) Load: 124 g / cm ² Lower surface plate rotation speed: 50 rpm Workpiece: BK7 glass material (manufactured by HOYA Co., Ltd.) □ 24 mm, 8 sheets / batch lap time: 5 minutes Lapping composition: water 3 kg, silicon carbide fine Powder 600g, and wrap oil (P81: Palace Chemical Co., Ltd.)
60 g was mixed with a blade stirrer and sufficiently dispersed Composition supply for wrapping: 200 cc / min)

Further, the silicon carbide fine powder for cutting abrasive grains according to the second aspect of the present invention is a silicon carbide fine powder for cutting abrasive grains for cutting hard and brittle materials, and is calculated by the above formula (1). The width of the particle size distribution is 0.9 or less, and the bulk specific gravity in water is 1.75 g / ml or more.
Here, the bulk specific gravity in water was 60 g of silicon carbide fine powder dried in an air bath at 110 ° C. for 12 hours, and a surfactant (Adecanol C-101: manufactured by Asahi Denka Co., Ltd.) 1% aqueous solution 60
In addition to g, a kneading machine (NBK-2, manufactured by Nippon Seiki Seisakusho Co., Ltd.) was sufficiently mixed to prepare a slurry, which was then transferred to a graduated cylinder having a cross-sectional area of 7 cm ² , and then the total amount of the slurry. Was added to water until it became 100 ml, and the mixture was sufficiently stirred, and the apparent volume of the precipitated silicon carbide fine powder after standing at 25 ° C. for 22 hours was measured, and the apparent volume was 60 g of the silicon carbide fine powder. Is obtained by dividing.

Further, the silicon carbide fine powder for cutting abrasive grains according to the third aspect of the present invention is a silicon carbide fine powder for cutting abrasive grains for cutting hard and brittle materials, and is calculated by the above formula (1). The width of the particle size distribution is 0.9 or less, and the average aspect ratio of the silicon carbide particles constituting the silicon carbide fine powder is 0.59 or more. Here, the average aspect ratio, in the projected cross section of the particle that can be obtained from the electron micrograph of the particle, the longest diameter is the longest diameter, the longest diameter perpendicular to the longest diameter is the shortest diameter, and the shortest diameter is the long diameter Is the average of the aspect ratios obtained by dividing by a sufficient number of particles.

The cutting composition according to the present invention is characterized by comprising the above-mentioned silicon carbide fine powder.

Further, the method for producing a silicon wafer according to the present invention is characterized in that the above composition for cutting is used to cut a silicon ingot with a wire saw.

According to the present invention, a large cutting speed and excellent processing accuracy can be achieved in cutting hard and brittle materials. Further, according to the present invention, it is possible to stably manufacture a silicon wafer having excellent processing accuracy.

[0021]

DETAILED DESCRIPTION OF THE INVENTION Silicon Carbide Fine Powder The silicon carbide fine powder according to the present invention is used for cutting. Although completely pure silicon carbide is a colorless and transparent crystal, it is generally industrially used to contain some impurities. Industrially used silicon carbide is generally classified into green silicon carbide and black silicon carbide. All of these are α-type silicon carbide crystals and are usually produced by thermally reacting silica with coke under conditions of 2000 ° C. or higher in an electric resistance furnace or the like.
Green silicon carbide has a hexagonal crystal structure and is said to have hardness second only to diamond. Further, the black silicon carbide has a characteristic that it is slightly inferior in hardness to the green silicon carbide but is excellent in toughness. The silicon carbide fine powder according to the present invention may use silicon carbide having any of these properties.

(1) Particle Size Distribution Width The silicon carbide according to the present invention has a specific particle size distribution width. Here, the particle size distribution width can be calculated from the particle size distribution curve. In the present invention, as an apparatus for measuring a particle size distribution curve, an electric resistance test method (JIS R600
The particle size was measured using Multisizer II (trade name: Beckman Coulter, Inc. (USA)) based on 2).
By using this apparatus, a cumulative frequency graph (particle size distribution curve) showing the frequency of the volume of particles contained in the section of the particle size on the horizontal axis and the particle size on the vertical axis can be obtained. At this time, the particle diameters at which the cumulative particle volume from the larger one reaches 3%, 50%, and 94% of the total particle volume are D (3%), D (50%), and D (9
4%), the average particle size and the particle size distribution width in the present invention are defined as follows. Average particle size = D (50%) Particle size distribution width = [(D (3%)-D (94%)] / D (50%)

The silicon carbide fine powder according to the present invention has a particle size distribution width determined by the above method of 0.9 or less, preferably 0.7 or less, and more preferably 0.65 or less from the viewpoint of maintaining the flatness of the processed surface. is there. Further, by setting the particle size distribution width of the silicon carbide fine powder within the above range, it is possible to suppress a decrease in yield when the cutting composition is recycled.

In the present invention, there is no lower limit to the particle size distribution width of the silicon carbide fine powder, and the smaller the particle size distribution width, the stronger the effect of the present invention is exhibited. In other words, the lower limit of the particle size distribution width is 0. However, in order to reduce the particle size distribution width, that is, in order to make the particle diameters uniform, it is necessary to further process the silicon carbide fine powder, and it is necessary to consider the cost increase for that.

Incidentally, the grain size distribution width of conventional abrasive grains for cutting was about 1.05 to 2.00. The silicon carbide fine powder according to the present invention is composed of silicon carbide particles having a particle diameter much more uniform than these.

The average particle size of the silicon carbide fine powder according to the present invention is not limited, but it maintains a sufficient cutting speed,
In addition, in order to keep the quality of the machined surface high enough, generally 3-25
μm, and preferably 5 to 20 μm.

(2) Lapping Speed Against Glass Material The silicon carbide fine powder according to the first embodiment of the present invention has a specific cutting efficiency in combination with the above-mentioned particle size distribution width. In the present invention, the lap speed with respect to the glass material is used as a measure of this cutting efficiency. The lapping speed with respect to the glass material in the present invention can be measured by lapping a glass material under the following conditions using a lapping composition containing fine silicon carbide powder. Lapping conditions Lapping machine: 4BT (manufactured by Hamai Seisakusho Co., Ltd.) Surface plate: Cast iron surface plate with grid-like grooves (groove width 2mm, groove cutting pitch 15m
m) Load: 124 g / cm ² Lower surface plate rotation speed: 50 rpm Workpiece: BK7 glass material (manufactured by HOYA Co., Ltd.) □ 24 mm, 8 sheets / batch lap time: 5 minutes Lapping composition: water 3 kg, silicon carbide fine Powder 600g, and wrap oil (P81: Palace Chemical Co., Ltd.)
60 g was mixed with a blade stirrer and sufficiently dispersed Composition supply for wraps: 200 cc / min

Under the above conditions, the glass material is polished with silicon carbide fine powder, and the lapping speed with respect to the glass material is calculated from the reduction amount of the thickness of the glass material. In the silicon carbide fine powder according to the present invention, from the viewpoint of sufficiently maintaining the cutting speed and suppressing the TTV of the processed surface, the value when the lap speed with respect to the glass material is expressed in μm / min is in μm unit. Represented D
Is less than or equal to the value represented by | [4.3 × D (50%) + 0.8] | and less than or equal to the value represented by | [3.8 × D (50%) + 0.5] | . Further, from the viewpoint of suppressing the machined surface Warp,
It is preferably not less than the value represented by | [D (50%)-0.5] |, and more preferably not less than the value represented by | [2 × D (50%)-0.5] |. In addition, also in the second and third aspects described later, it is preferable that the lapping speed with respect to the glass material is within this range.

(3) Bulk Specific Gravity in Water The silicon carbide fine powder according to the second embodiment of the present invention has a specific bulk specific gravity in addition to the above-mentioned particle size distribution width. In the present invention, the bulk specific gravity in water is adopted as a material showing this bulk specific gravity. The bulk specific gravity in water in the present invention is measured by the following method.

60 g of silicon carbide fine powder, which has been dried in an air bath at 110 ° C. for 12 hours and cooled to room temperature while maintaining the dry state, is weighed. This silicon carbide fine powder was added to 60 g of a 1% aqueous solution of a surfactant (Adecanol C-101: manufactured by Asahi Denka Kogyo Co., Ltd.) and a kneading machine (NBK-2, manufactured by Nippon Seiki Seisakusho Co., Ltd.) was used to sufficiently Mix to prepare a slurry. This slurry was transferred to a graduated cylinder having a cross-sectional area of 7 cm ² , water was added until the total amount of the slurry reached 100 ml, and the mixture was sufficiently stirred and then allowed to stand at 25 ° C. After standing for 22 hours, the apparent volume of the precipitated silicon carbide fine powder, that is, the scale (ml) of the graduated cylinder showing the bulkiness is read, and the bulk specific gravity in water is calculated from the following formula. Bulk density in water (g / ml) = 60 (g) / apparent volume of fine silicon carbide powder (ml)

The bulk specific gravity in water according to the present invention is completely different from the bulk specific gravity generally used.

The silicon carbide fine powder according to the second embodiment of the present invention has a bulk specific gravity in water of 1.75 g / ml or more and 1.80 from the viewpoint of sufficiently maintaining the cutting speed and suppressing the TTV of the processed surface. It is preferably g / ml or more. In the first aspect and the third aspect described below according to the present invention, it is preferable that the bulk specific gravity in water is within this range.

(4) Average Aspect Ratio The silicon carbide particles forming the silicon carbide fine powder are generally not spherical but are polyhedra having edges. In the present invention, the aspect ratio is adopted as a parameter indicating such a particle shape. This aspect ratio can be determined by determining the major axis and minor axis of the particle and dividing the minor axis by the major axis. This aspect ratio is determined for a sufficient number of particles having a typical shape, and the average thereof is used as the average aspect ratio of the silicon carbide fine powder. The specific number of particles measured when determining the aspect ratio is generally 20 or more, preferably 100 or more, and more preferably 1000 or more. It is preferable to obtain the aspect ratio of more particles for the purpose of reducing errors due to selection and measurement of particles, but it is necessary to consider the cost increase for that purpose. The major axis and the minor axis of the particles are the projected diameter of the particle that can be obtained from an electron micrograph of the particle, and the longest diameter is the major axis.
The longest diameter perpendicular to the longest diameter is defined as the shortest diameter.

The silicon carbide fine powder according to the third aspect of the present invention has an average aspect ratio of 0.59 in combination with the particle size distribution width from the viewpoint of maintaining a sufficient cutting speed and suppressing TTV of the processed surface. It is above, and it is preferable that it is 0.63 or above. Further, from the viewpoint of stabilizing the cutting process and suppressing the warp of the processed surface, it is preferably 1.0 or less, and more preferably 0.95 or less.
In the first and second aspects of the present invention as well, it is preferable that the aspect ratio of the particles is within this range.

Preparation of Silicon Carbide Fine Powder Although the silicon carbide fine powder according to the present invention can be prepared by any method, it is generally prepared by pulverizing and classifying silicon carbide particles having a larger particle size. To do.

Cutting Composition The cutting composition according to the present invention comprises the above-mentioned silicon carbide fine powder and a cutting working liquid.

The cutting liquid used in the composition for cutting according to the present invention may be selected from any known cutting liquid, and may be a glycol compound, a refined mineral oil, and a surfactant. Those containing at least one selected from the group as a main component are preferable.

Here, as the glycol compound, monoalkylene glycols such as ethylene glycol,
Propylene glycol, and other polyalkylene glycols such as the general formula R ₁ —O— (CH ₂ CH
₂ O) _n —R ₂ (wherein R ₁ and R ₂ are each independently hydrogen, an alkyl group having 1 to 4 carbon atoms or an acyl group having 2 to 5 carbon atoms, and n is an integer of 3 to 22) Is)
A polyalkylene glycol represented by
When polyalkylene glycols are used as the glycol compound, it is preferable that the average molecular weight calculated from the hydroxyl value is 1000 or less, particularly 200 to 500, from the viewpoint of appropriately maintaining the viscosity of the entire composition.

The refined mineral oil is not particularly limited, but at least one selected from the group consisting of single naphthenic base oil, mixed naphthenic base oil and isoparaffin refined mineral oil in terms of solubility. Preferably there is.

Further, the surfactant is not particularly limited, but a total amine value of 50 having a cationic water-soluble resin having an amine value of 20 to 200 mgKOH / g, a tertiary amino group and a quaternary ammonium salt-containing group. It is preferably a cationic water-soluble resin of ˜200 mg KOH / g. For example, the following water-soluble resins may be mentioned. (1) A homopolymer or copolymer of a vinyl-based monomer containing a basic nitrogen atom or a salt thereof or a quaternary ammonium salt. (2) Polycondensation product of dicarboxylic acid and polyethylene polyamine or dipolyoxyethylene alkylamine, its salt or quaternary ammonium salt. (3) Polymer of dihaloalkane and polyalkylene polyamine. (4) A polyaddition product of diepoxide and a secondary amine, a salt thereof, or a quaternary ammonium salt. (5) Polyaddition product of diisocyanate and diamine, its salt or quaternary ammonium salt.

Further, the cutting working liquid may contain water as required. By adding water, the flashing point of the cutting composition can be raised and the safety can be improved.

Further, the cutting composition according to the present invention contains various additives for the purpose of maintaining and stabilizing the quality of the composition, or depending on the type of the workpiece, the processing conditions, and other factors. Can be As such an additive, any known one can be selected.

Among such additives, the viscosity improver is particularly one which adjusts the viscosity of the cutting composition and imparts appropriate thixotropy to the composition, and is preferably added. The viscosity improver that can be used is not particularly limited as long as it exhibits such an action,
Examples thereof include organic polymer compounds and inorganic polymer compounds.

Organic polymer compounds can be roughly classified into synthetic organic polymer compounds and natural organic polymer compounds. As the synthetic organic polymer compound, polyacrylic acid, polyacrylamide, methyl cellulose, carboxymethyl cellulose, hydroxymethyl cellulose and hydroxyethyl cellulose are preferable. As the natural organic polymer compound, polymer polysaccharide or vegetable gum is preferable,
Specific examples include xanthan gum, gum arabic, tragacanth gum, dextran, and others. Of these, xanthan gum is particularly preferable.

As the inorganic polymer compound, montmorillonite group minerals are preferable. Montmorillonite minerals include bentonite, montmorillonite, magnesium montmorillonite, beidellite, hectorite, and others. Contains montmorillonite as the main component,
Bentonite, which is easily available, is preferably used.

The content of the silicon carbide fine powder in the cutting composition according to the present invention is such that the weight of the whole cutting composition is adjusted from the viewpoint that the viscosity of the whole composition is made appropriate while keeping the cutting speed sufficiently high. As a standard, generally 20-80%,
It is preferably 30 to 70%.

The cutting composition according to the present invention is prepared by mixing, dissolving or dispersing the above-mentioned components. The method of dispersing or dissolving each component is arbitrary, and for example, the components are stirred by a blade stirrer or dispersed by ultrasonic dispersion. Further, the order of adding these respective components is arbitrary, and any of them may be dispersed or dissolved first or simultaneously dispersed or dissolved.

The cutting composition according to the invention comprises a cutting device,
For example, it can be used for a wire saw cutting device (wire saw), an inner peripheral blade type cutting device, and an outer peripheral blade type cutting device, but is particularly used for cutting hard and brittle materials with a wire saw. Hard brittle materials to be cut include silicon, GaAs, InP, and Ga.
Examples thereof include semiconductor materials such as P, metal oxides such as LiTaO ₃ and LiNbO ₃ , glass materials such as soda lime glass, tempered glass, and crystallized glass, ferrite, and quartz.

Method for Manufacturing Silicon Wafer The method for manufacturing a silicon wafer according to the present invention is to cut a silicon ingot with a wire saw using the above-mentioned composition for cutting according to the present invention. The wire saw device is not particularly limited, and any cutting condition can be used as necessary.

When cutting a hard and brittle material using the cutting composition according to the present invention, the reason why it is possible to obtain an excellent processing accuracy and a uniform processed surface with few saw marks while maintaining a relatively high cutting speed is described. Although it has not been clarified in detail, the following can be inferred when the cutting of a silicon ingot by a wire saw is taken as an example.

First, the reason why a high cutting speed and a uniform machined surface with few saw marks can be obtained are as follows.
The silicon carbide fine powder according to the present invention is excellent in grindability due to its high hardness, and has a uniform particle shape and particle size due to its narrow particle size distribution width, and is subjected to uniform processing on a silicon ingot. It is considered that it is done.

During cutting with a wire saw, the silicon carbide fine powder is entrained in the wire through the cutting composition and enters the cutting portion between the wire and the silicon ingot. When coarse particles are mixed in the fine powder, the coarse particles cut the silicon ingot near the entrance of the cutting portion at a high speed, but it is difficult to enter the inside of the ingot due to the large particle size. Further, since silicon carbide has a high hardness, it cannot be expected that it will be crushed by the impact at the time of cutting and enter the inside of the ingot. Therefore, only the cut portion of the ingot is processed by the coarse particles at a high cutting speed, and the inside is processed by the relatively small particles at a relatively low cutting speed. As a result, it is considered that the silicon ingot (wafer) after cutting has a variation in thickness, which deteriorates the TTV of the processed surface.

Further, when cutting is performed using a cutting liquid containing a large amount of silicon carbide fine powder having a small aspect ratio or bulk specific gravity in water or a high glass lapping speed, the composition for cutting is Depending on how the wire is attached to the wire, the size of the groove formed when the wire cuts the silicon ingot, that is, the cutting width, easily varies. As a result, similarly to the case where coarse particles are mixed, it is considered that the TTV of the processed surface is deteriorated due to the variation in the thickness of the silicon ingot (wafer) after cutting. In addition, since particles of such a silicon carbide fine powder are easily broken by an impact at the time of cutting, variation in thickness of wafers between processing (cutting) batches causes TTV of a processed surface to deteriorate, and
When the cutting composition containing such silicon carbide fine powder is recycled, the yield (recovery rate) of the silicon carbide fine powder is higher than that in the case where the cutting liquid containing the silicon carbide fine powder according to the present invention is used. ) Will be lower.

On the other hand, when cutting is performed using a cutting composition containing silicon carbide fine powder having an extremely low lapping speed against glass, the cutting ability of the cutting composition is lower than the table feed speed of the wire saw. As a result, the wire is likely to bend. As a result, it is considered that waviness is likely to occur in the cut wafer and the Warp of the processed surface is deteriorated.

On the other hand, the cutting composition according to the present invention uses silicon carbide fine powder having a narrow particle size distribution width, that is, uniform particle size, and therefore the above-mentioned deterioration of the quality of the processed surface is unlikely to occur. .

[0056]

EXAMPLES The following examples are for specifically explaining the method for producing a cutting composition and a silicon wafer according to the present invention, and are not for limiting the present invention.

Preparation of Silicon Carbide Fine Powder Green silicon carbide having an average particle diameter of 40 μm was crushed using a ball mill and classified by wet classification to prepare silicon carbide fine powder as shown in Tables 1 to 6. With respect to these silicon carbide fine powders, the particle size distribution width, the lapping speed with respect to the glass material, the bulk specific gravity in water, and the average aspect ratio were measured by the methods described above. These measured values are shown in Tables 1-6.
Was as shown in.

Preparation of Cutting Composition A cutting composition was prepared by adding 60 kg of each silicon carbide fine powder shown in Tables 1 to 6 with stirring to a working fluid of 60 kg, mixing and dispersing. The working liquids used are the following three types. Working fluid A: Glycol-based cutting fluid HS-24J (trade name) Processing fluid B: Water-based cutting fluid TD-98001 (trade name) Processing fluid C: Oil-based cutting fluid WS-2Q (trade name) (both (Fujimi Incorporated)

Working liquid B was added to the cutting composition of Example 7,
Working fluid C was used for the cutting composition of Example 8, and working fluid A was used for the cutting compositions of the other Examples and Comparative Examples.

Cutting Test 1 A cutting test with a wire saw was performed using the cutting composition of each example. The cutting conditions were as follows.

Cutting Conditions 1 Object to be cut: Silicon ingot (diameter 8 inches, length 150
mm) Cutting device: Multi wire saw (manufactured by HCT (Switzerland)) Wire diameter: 180 μm Wire tension: 30 Nm Wire speed: Average 6.5 m / sec Cutting speed: Average 380 μm / min

After cutting, the wafer was thoroughly washed with a chemical and water and dried, and then a measuring device ADE9500 (manufactured by AD Co., Ltd. (US)) was used to measure the wafer processing accuracy of TTV. And Warp were measured. The criteria for Warp are as follows. ◎: Less than 10 μm ○: 10 μm or more and less than 20 μm ×: 20 μm or more

The obtained results are as shown in Tables 1 to 6.

[0064]

[Table 1]

[0065]

[Table 2]

[0066]

[Table 3]

[0067]

[Table 4]

[0068]

[Table 5]

[0069]

[Table 6]

From these results, the particle size distribution width of the particles,
It can be seen that the cutting composition comprising the silicon carbide fine powder according to the present invention in which the lapping speed with respect to the glass material, the bulk specific gravity of particles in water or the average aspect ratio is appropriately adjusted can achieve a high cutting speed and excellent processing accuracy. .

Cutting Test 2 Using the silicon carbide fine powder used in Example 10 and Comparative Example 5, a cutting test was conducted by changing the material to be cut into artificial quartz. FC-10 (trade name) sold by Rika Shokai Co., Ltd. was used as the working liquid, and 1.0 liter of the working liquid was mixed with 1.1 kg of silicon carbide fine powder to prepare a cutting composition.

Cutting test 2 Object to be cut: artificial quartz (width 20 mm, height 10 mm, length 210 mm) Cutting device: multi-wire saw (HCT (Switzerland)
Made) Wire diameter: 180μm Wire tension: 30N ・ m Wire speed: Average 6.5m / sec Cutting speed: Average 380μm

Five batches of polishing were performed under the above conditions.

After cutting, the wafer was thoroughly dried with chemicals and water, and then the thickness accuracy (in-plane and batch-to-batch variation) and kerf loss (wire guide pitch and The difference from the thickness of the center of the wafer surface after cutting) was measured. The criteria for determining the thickness accuracy are as follows. ◎: In-plane variation in each batch is 0.003 mm or less, variation between batches is 0.007 mm or less ○: In-plane variation in each batch is 0.003 mm or more, or variation between batches is 0.007 mm or more ×: In-plane variation in each batch is 0.003 mm Above, variation between batches 0.007mm or more

The results obtained are shown in Table 7. Regarding kerf loss and yield, Comparative Example 5
The relative value of Example 10 is shown.

[0076]

[Table 7]

The cutting composition of Example 10 has a higher thickness accuracy (between batches and in-plane variation) than the cutting composition of Comparative Example 5, and in addition, can be cut. Little kerf loss. As a result, the processing yield can be improved.

[0078]

According to the present invention, in cutting hard and brittle materials, a high cutting speed and excellent working accuracy can be achieved. Further, according to the present invention, it is possible to stably manufacture a silicon wafer having excellent processing accuracy.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takaya Hasegawa             Aichi Prefecture Nishi Kasugai-gun Nishibiwajima-cho 2 territory 1             Address 1 Fujimi Incorporated             In Ted (72) Inventor Kenichi Ito             Aichi Prefecture Nishi Kasugai-gun Nishibiwajima-cho 2 territory 1             Address 1 Fujimi Incorporated             In Ted (72) Inventor Yasumitsu Sasaki             Aichi Prefecture Nishi Kasugai-gun Nishibiwajima-cho 2 territory 1             Address 1 Fujimi Incorporated             In Ted F-term (reference) 3C047 FF06 GG20                 3C058 AA05 CA01 CA04 CB01 DA02                       DA03                 3C069 AA01 BA06 BB01 BB04 CA04                       EA01 EA02

Claims (7)

[Claims] 1. A silicon carbide fine powder for cutting abrasive grains for cutting a hard and brittle material, having a particle size distribution width of 0.9 or less calculated by the following formula (1) and a lapping speed with respect to a glass material. A silicon carbide fine powder for cutting abrasive particles, characterized in that it is within the range of the following formula (2). Particle size distribution width = [D (3%)-D (94%)] / D (50%) (1) ｜ [D (50%)-0.5] ｜ ≦ ｜ Lapping speed for glass material ｜ ≦ ｜ [4.3 × D (50%) + 0.8] | (2) (where D (3%), D (50%), and D (94%) are the total particle volume from the large particle size side. Each 3%,
The particle diameter reaches 50% and 94%, and in the formula (2), D (50%) and the lapping speed with respect to the glass material are numerical values expressed in μm and μm / min, respectively. Is calculated from the amount of decrease in the thickness of the glass material when the silicon carbide fine powder is used for lapping under the following lapping conditions. Lapping machine: 4BT (manufactured by Hamai Seisakusho Co., Ltd.) Surface plate: Lattice-shaped grooved cast iron surface plate (groove width 2 mm, groove cutting pitch 15 m
m) Load: 124 g / cm ² Lower surface plate rotation speed: 50 rpm Workpiece: BK7 glass material (manufactured by HOYA Corporation) □ 24
mm, 8 sheets / batch wrap time: 5 minutes Composition for wrap: 3 kg of water, 600 g of silicon carbide fine powder, and wrap oil (P81: manufactured by Palace Chemical Co., Ltd.)
60 g was mixed with a blade stirrer and sufficiently dispersed Composition supply for wrapping: 200 cc / min) 2. A silicon carbide fine powder for cutting abrasive grains for cutting a hard and brittle material, which has a particle size distribution width of 0.9 or less calculated by the following formula (1) and a bulk specific gravity in water of 1.75 g. / ml
The above is the silicon carbide fine powder for cutting abrasives, which is characterized by the above. Particle size distribution width = [D (3%)-D (94%)] / D (50%) (1) (where D (3%), D (50%), and D (94%) are The cumulative particle volume from the large particle size side is 3% of the total particle volume,
The particle size is 50% and 94%, and the bulk specific gravity in water is 60 g of silicon carbide fine powder dried in an air bath at 110 ° C. for 12 hours, using a surfactant (Adecanol C-101: Asahi Denka Kogyo Co., Ltd.). in addition to Ltd.) 1% aqueous solution 60 g, kneader (NBK-2, a slurry prepared by mixing thoroughly using Nippon Seiki Seisakusho), moves the slurry in cross-sectional area in the graduated cylinder 7 cm ² After that, add water until the total volume of the slurry reaches 100 ml, stir it sufficiently, and leave it at 25 ° C for 22 hours to measure the apparent volume of the precipitated silicon carbide fine powder. It is obtained by dividing the weight of fine powder by 60 g. ) 3. A silicon carbide fine powder for cutting abrasive grains for cutting a hard and brittle material, having a particle size distribution width of 0.9 or less calculated by the following formula (1) and constituting a silicon carbide fine powder. The silicon carbide fine powder for cutting abrasives, wherein the average aspect ratio of the silicon carbide particles to be formed is 0.59 or more. Particle size distribution width = [D (3%)-D (94%)] / D (50%) (1) (where D (3%), D (50%), and D (94%) are The cumulative particle volume from the large particle size side is 3% of the total particle volume,
The particle diameter reaches 50% and 94%, and the average aspect ratio is the longest diameter in the projected cross section of the particle that can be obtained from the electron micrograph of the particle, and the longest diameter is the longest in the diameter perpendicular to this long diameter. It is the average value for the sufficient number of particles of the aspect ratio obtained by dividing the minor axis by the major axis with the minor axis as the minor axis.) 4. The fine silicon carbide powder according to claim 1, wherein D (50%) is 3 to 25 μm. 5. A cutting composition comprising the silicon carbide fine powder according to any one of claims 1 to 4. 6. The cutting composition according to claim 5, further comprising at least one selected from the group consisting of a glycol compound, a refined mineral oil, and a surfactant. 7. A method for producing a silicon wafer, which comprises cutting the silicon ingot with a wire saw using the cutting composition according to claim 5 or 6.