JPH11198045A - Polishing molded body, polishing surface plate and polishing method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the problems of drainage by using abrasive liquid including little or a little free abrasive grains, effectively polish materials to be polished by the same extent of polishing as that in a conventional polishing method and highly effectively perform polishing work by the durability of molded bodies for polishing in a polishing process in polishing substrate materials such as semiconductor substrates such as silicon wafers and oxide substrates and optical materials requiring precision machining. SOLUTION: Polishing molded bodies, comprise mainly ceria (oxidation cerium), and their bulk density is 0.7 g/cm<3> or more and 5.0 g/cm<3> or less, and BET ratio surface area is 2 m<2> /g or more and 200 m<2> /g or less, and mean particle diameter is 0.001 μm or more and 0.5 μm or less. A polishing surface plate and a polishing method using the molded bodies for polishing are used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molded article for use in a method for polishing a substrate material such as a silicon wafer or an oxide substrate, an optical material, and the like, a polishing platen using the same, and a polishing method. Things. For more information,
The present invention relates to a formed body for polishing obtained by subjecting a ceria formed body formed of fine ceria powder to processing such as firing, a polishing platen using the same, and a polishing method.

[0002]

2. Description of the Related Art With the development of industries such as optics and electronics, demands for processing magnetic disks, semiconductor substrates, single crystal materials and the like have become extremely strict. In particular, in the finishing of electronic components, polishing is performed with a polishing pad of a nonwoven fabric type or a suede type while continuously flowing a polishing liquid containing free abrasive grains on the surface of the material. As the free abrasive grains used, alumina, silica, ceria, zirconia, and the like are known. Among them, ceria has good compatibility with optical glass, and is superior when focusing on both processing quality and economy of processing. Due to the lack of materials, it has become a mainstay especially for glass polishing.

However, according to such a method, since a polishing liquid containing free abrasive grains is used, a polishing waste liquid containing a large amount of free abrasive grains is generated after the polishing treatment. It should be improved in consideration of the impact on wastewater treatment facilities and the environment.
Further, in the polishing process, the polishing cloth needs to be frequently replaced with a new one because the performance deteriorates such as clogging, and there is also a problem in terms of efficiency of the polishing process.

Further, in the case of a material polished by a conventional polishing method using a polishing cloth (hereinafter referred to as a "material to be polished"), since the surface of the polishing cloth is soft, the corner of the end of the material to be polished is being polished. There is a disadvantage that the polishing is excessively performed so that the entire surface of the material to be polished cannot be uniformly polished, resulting in an inefficient finish.

[0005]

As described above, when the polishing process is performed by the conventional method, problems such as a problem of treatment of a polishing waste liquid generated during polishing, an effective use of a material to be polished, and an efficiency of a polishing operation occur. Thus, the present invention has been made in view of such a problem. The purpose is to use a polishing liquid that does not contain free abrasive grains or contains a small amount of free abrasive grains in the processing process of polishing substrate materials such as semiconductor substrates such as silicon wafers, oxide substrates, and optical materials that require precision processing. By reducing the problem of waste liquid, the material to be polished can be polished efficiently with the same level of polishing finish as the conventional method, and the polishing work is more efficient because the polishing molded body has durability in the polishing process An object of the present invention is to provide a molded article for polishing, a polishing platen and a polishing method using the same.

[0006]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, have found that a ceria molded body molded using ceria fine powder is processed and used as a polishing molded body. Found the following findings.

1) During polishing, the surface of the molded article for polishing is roughened by ceria fine powder, which is a raw material thereof, and this comes into direct contact with the material to be polished. It can be applied to the polishing process of substrate materials etc. using a polishing liquid that does not contain free abrasive grains, and at that time, the problem of waste liquid is reduced because the number of particles of the compact is very small. You.

[0008] 2) Since the strength of the molded article for polishing is high, it is durable even in the polishing process, so that the polishing operation can be performed for a long time without replacement.

3) The finish of the material to be polished is almost the same as that of the conventional method, the polishing speed is the same, and the polishing performance does not deteriorate with time.

4) Even when an abrasive containing free abrasive grains is used, the polishing rate is improved at a concentration of the free abrasive grains which is lower than that of the conventional method.

As described above, these excellent points have been found by using the polishing molded article of the present invention, the polishing platen and the polishing method using the same, and the present invention has been completed.

Hereinafter, the present invention will be described in detail.

<Characteristics of Polished Molded Article> The polishing molded article of the present invention is mainly composed of ceria (CeO ₂ ), that is, cerium oxide, and has a bulk density of 0.7 g / cm ³ or more.
0 g / cm ³ or less, a BET specific surface area of 2 m ² / g or more and 200 m ² / g or less, and an average particle size of 0.0
It is not less than 01 μm and not more than 0.5 μm.

Mainly, ceria is preferably used in which the ceria component has a content of 90% by weight or more, more preferably 97% by weight or more of the total amount of the molded article for polishing.

Here, as the range of the bulk density of the molded article for polishing, the shape of the molded article for polishing is maintained while polishing.
To obtain a smooth surface of the material to be polished efficiently, 0.7 g /
The range is preferably not less than cm ^{3 and not} more than 5.0 g / cm ³ , more preferably not less than 1.3 g / cm ^{3 and not} more than 3.0 g / cm ³ . If the bulk density is less than 0.7 g / cm ³ , the shape cannot be maintained, and the shape retention will be poor. Also,
If it exceeds 5.0 g / cm ³ , on the contrary, the strength of the molded body itself becomes too high, the material to be polished is damaged during polishing, or the surface of the molded body for polishing becomes too smooth due to polishing, and the polishing rate is reduced. It is not preferable because it decreases.

The range of the BET specific surface area of the molded article for polishing is 2 m ² / g or more in order to maintain the shape of the molded article for polishing and obtain a smooth surface of the material to be polished.
m ² / g or less, more preferably 2 m ² / g or more and 1
00m ² / g or less, in particular 2m ² / g or more 55m range ² / g are preferred. If the BET specific surface area is more than 200 m ² / g, the shape of the molded article for polishing cannot be maintained, so that the shape retention is deteriorated. On the other hand, if it is less than 2 m ² / g, on the contrary, the strength of the molded body itself becomes too high, the material to be polished is damaged during polishing, and the surface of the molded body for polishing becomes too smooth due to polishing, and the polishing rate is reduced. It is not preferable because it decreases.

The range of the average particle diameter of the abrasive compact is 0.001 μm or more and 0.5 μm or less, more preferably 0.01 μm or more in order to facilitate molding into a porous body and obtain a smooth surface of the material to be polished. 0.3 μm or less, especially 0.03 μm
The range is preferably not less than 0.2 μm and not more than 0.2 μm. When the average particle diameter is smaller than 0.001 μm, the primary particle diameter of the raw material powder becomes smaller than 0.001 μm, and it becomes very difficult to mold the raw material powder into a porous body. Is also undesired because problems such as defects occurring in the material to be polished may occur. Here, the average particle diameter means the particle diameter of ceria fine particles on the surface of the molded article for polishing, and can be measured by, for example, a scanning electron microscope (SEM) as described in Examples.

<Manufacturing Method of Polishing Molded Body> The polishing molded body of the present invention is obtained by processing a ceria molded body molded by using ceria fine powder into a molded body by processing such as firing.
There is no particular limitation as long as it has the characteristics described above.

The ceria molded body can be produced, for example, by applying pressure to the raw material powder and molding. When molding under pressure, for example, molding methods such as press molding can be exemplified,
As the pressure condition, a pressure of 5 kg / cm ² or more is usually preferably used to maintain the shape of the obtained molded body, and a pressure of 10 kg / cm ² or more is more preferably used.

Further, in order to improve the formability of the raw material powder, the raw material powder may be subjected to a treatment. As a method of the treatment, for example, a method of preforming by press molding or the like and then classifying using a sieve or the like can be given. The pressure at the time of preforming is not fixed depending on the properties of the powder and the like, but usually 5 kg / cm ² or more and 1000 kg / cm ² or less is sufficient. Similarly, in order to improve the moldability of the raw material powder, granulation may be performed by a spray-dry method, a rolling method, or the like, or a binder, a wax, or the like may be added.

Similarly, in order to improve the formability of the raw material powder, the raw material powder may be granulated by a spray drying method, a rolling method, or the like, or a binder may be added. You may mix with a pore-forming agent so that it may not collapse. The moldability is improved by these additives, and by using the pore-forming agent, a ceria molded body reflecting the particle diameter of the pore-forming agent can be obtained, and the pore structure in the molded body for polishing can be easily controlled. As a result, a molded article for polishing that can improve the polishing rate during polishing is obtained. Before mixing the granulated powder with the pore-forming agent, the granulated powder may be temporarily transferred and stored.

When a binder is used, it can be used without any particular limitation as long as it does not hinder the granulation operation, but usually a binder, a plasticizer, a lubricant, etc. can be used. Examples thereof include acrylic resins, polyolefin resins, waxes, lower fatty acids such as stearic acid, and higher alcohols such as stearyl alcohol, and these can be used alone or in combination of two or more.

When a pore-forming agent is used, the types of the pore-forming agent include waxes such as paraffin wax and microcrystalline wax, powders of acrylic resins such as polymethyl methacrylate and polybutyl methacrylate, polyethylene, polypropylene, ethylene / acetic acid. Vinyl copolymer, olefin resin powder such as ethylene / ethyl acrylate copolymer, polystyrene powder, lower fatty acid powder such as stearic acid, potato starch, corn starch, ethyl cellulose, carbon powder, etc. One type or two or more types can be used.

When an organic substance such as a binder or a pore-forming agent is added to the raw material powder before molding in order to improve the formability of the raw material powder into a ceria molded body, when the raw material powder is processed into a molded body for polishing, it is degreased. Is preferred. The degreasing method is not particularly limited, and examples thereof include degreasing by heating in an air atmosphere, and degreasing by heating in an inert atmosphere such as nitrogen, argon, and helium. At this time, the pressure of the atmosphere gas may be under pressure or under normal pressure, and may be under reduced pressure in some cases. Similarly, in order to improve the moldability, it is also possible to add moisture and to dry before the subsequent firing operation.

Next, the molded body from which the binder has been removed is
Generally, since the strength is weak, it is preferable to perform sintering by heating in order to increase the strength and improve the durability as a polishing platen. However, the method for improving the durability is not limited to heating and firing.

As described above, examples of a method of processing the ceria molded body into a molded body for polishing include a method using heat degreasing, heating and baking, machining, and the like. There is no particular limitation as long as the processing method can be performed.

<Structure of Polishing Surface Plate> Next, a method of assembling the molded body for polishing as a polishing surface plate and further performing polishing using the platen will be described.

First, a polishing platen is formed by using a polishing compact and a polishing accessory.

Here, the auxiliary parts are structures of various materials and shapes constituting a polishing platen, and a molded body for polishing is arranged on the auxiliary parts by a method described below.
The polishing platen is formed by fixing. As a method of fixing both, a method of bonding and fixing using an adhesive such as an elastic adhesive, a method of forming irregularities on ancillary parts, embedding in the fixing place, and the like, a method that can achieve the object of the present invention. If there is, it can be used without restriction.

The number of the shaped bodies for polishing when the shaped body for polishing is fixed to the accessory part for grinding may be one or more, and more preferably two or more. This is because 1) the polishing rate is improved by appropriately discharging the polishing liquid used in the polishing process during polishing. Therefore, when the polishing platen is formed by using two or more polishing compacts, the polishing liquid can be discharged from the gap between the polishing compacts. When one is used, it is preferable to provide an appropriate groove structure capable of discharging the polishing liquid on the side of the polishing surface of the molded body. 2) Further, when the polishing platen is formed by using two or more polishing compacts, the contact with the material to be polished is improved, and the polishing speed is improved without unevenness in the polishing rate over the entire surface of the material to be polished. become able to.

The shape of the abrasive compact to be used is not particularly limited, and any shape can be adopted as long as the abrasive compact can be attached to the accessory part for polishing. For example, columnar pellets, square columnar pellets,
Examples include prismatic pellets such as triangular prism pellets,
Furthermore, any shape in which the contact surface with the material to be polished can be formed by combining a straight line and a curve can be exemplified. The size is not particularly limited as long as it is within a range normally used, and is determined according to the size of an accessory part for incorporating a molded body for polishing in a polishing table.

The mode of the method of arranging the molded article for polishing used in the present invention as a polishing platen is not particularly limited as long as it is a combination of those having the characteristics of the molded article for polishing described above. Instead, for example, a method of combining and integrating small pieces of a molded article for polishing, a method of embedding in a large disk, and the like can be mentioned.

When two or more such compacts for polishing are arranged on a polishing plate, it is desirable to arrange the polished surface of the disposed compact for polishing so as to match the shape of the material to be polished. In this case, it is possible to select an accessory that matches the shape of the accessory. For example, when the surface of the material to be polished is flat, it is desirable to flatten the contact surface of the molded body for polishing with the material to be polished, and when it is a curved surface, it is desirable to have a curved surface conforming thereto. This ensures that the material to be polished and the molded body for polishing can be in direct contact with each other when polishing is performed using the obtained polishing surface plate, so that a large contact surface can be obtained. That's why. In particular, in the case of flattening, it is preferable to arrange them so that there is no variation in the vertical height from the polishing platen.

With respect to the method of fixing the molded body for polishing and the metal platen, the molded body for polishing is fixed by fixing with an adhesive or by forming an uneven surface corresponding to the size of the molded body for polishing on the metal platen. You may. The adhesive used when fixing the molded body for polishing and the metal platen using an adhesive can be used without particular limitation as long as the object of the present invention can be achieved, and in particular, such as an elastic adhesive In addition, it is preferable to use an adhesive that does not have cracks, cracks, or the like that may occur when the polishing molded body is fixedly adhered to the surface plate.

<Polishing Method Using Polishing Surface Plate> In this manner, the molded body for polishing is incorporated into the polishing surface plate. In the method of polishing using the polishing surface plate of the present invention, The shape, polishing conditions, use of a polishing liquid, and the like are not particularly limited as long as the surface plate is used in the polishing process. For example, when a polishing liquid is used, a conventionally used polishing liquid may be used, and for example, water can be used.

Here, the polishing platen is used to polish the molded body for polishing directly in contact with the material to be polished, has sufficient strength in the polishing process, and What is necessary is just to have the performance which can polish an abrasive material. Therefore, the shape may have not only the same shape as the material to be polished, but also a non-planar shape if necessary. For example, flat, disk, ring,
A cylindrical shape or the like can be given.

Further, since the polishing method of the present invention does not use a polishing cloth, the interruption of the polishing operation due to the replacement of the polishing cloth due to the deterioration of the performance of the polishing cloth, which has been observed in the conventional method during polishing, must be avoided. The use of the abrasive compact has the advantage that durability is improved and replacement frequency can be reduced, so that the efficiency of the polishing operation can be increased.
Further, with respect to the polishing waste liquid containing free abrasive grains generated in the conventional method using an abrasive, the use of the free abrasive grains by using the molded article for polishing according to the present invention or the use of a small amount is sufficient. The amount of free abrasive grains and grains generated by polishing is reduced, and the problem of waste liquid treatment is reduced. For example, the transmittance when irradiating the polishing waste liquid is higher than that in the conventional method,
It can be confirmed that the amount of unnecessary particles mixed in the polishing waste liquid is reduced. Considering the problem of the polishing waste liquid, the transmittance of the polishing waste liquid at 600 nm is 10% of water.
As described above, it is particularly preferable to set the polishing liquid to 40% or more, and it is preferable to use a polishing liquid having such a transmittance of the waste liquid.

The polishing platen of the present invention may be made of a silicon wafer, a semiconductor substrate such as gallium phosphide or gallium arsenide, an oxide substrate such as lithium niobate, lithium tantalate or lithium borate, a substrate material such as a glass substrate, quartz. It is useful for polishing glass, metal materials, stone materials used in the construction field, and the like. Of these, a polished material can be made effective because there is no surface sagging compared to a method using a conventional polishing cloth, and it is preferably used as a substrate material, and further preferably used as a semiconductor substrate, an oxide substrate, and a glass substrate. Can be

[0039]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto. In addition, each evaluation was implemented by the method shown below.

~ Ceria content ~ Measured by ICP emission spectroscopy.

-Bulk Density-A flat sample of 100 mm x 100 mm x 15 mm (thickness) was prepared and used as a sample of a molded body. This sample was calculated from the weight measured with an electronic balance and the shape and dimensions measured with a micrometer.

[Average Particle Diameter] A part of the surface of the molded article for polishing is adjusted to be flat, and the surface is observed with a scanning electron microscope ISIDS-130 (manufactured by Akashi Seisakusho). It was determined by the intercept method.

-BET specific surface area-The raw material powder was used as it is, and the molded body for polishing was used for measurement after crushing it. The measurement was carried out after drying at 200 ° C. for 15 minutes using MONOSORB (QUANTAC, USA).
(HROME Co., Ltd.) using the BET one-point method.

~ Average Particle Diameter of Powder ~ Ceria powder was used as a sample, and COULTER LS13
0 (manufactured by COULTERELECTRONICS) using a liquid module. Measurements are on a volume basis.

Polishing Test A cylindrical test piece of a molded body having a diameter of 25 mm and a thickness of 5 mm was prepared, and was rotated on a rotating platen (360 m in diameter) of a high-speed lens polishing apparatus.
m), and the surface of the molded article was flattened. Under the conditions of a platen rotation speed of 100 rpm and a processing pressure of 150 g / cm ² of the material to be polished on the surface plate, six quartz glass substrates having a diameter of 3 inches are simultaneously used as the material to be polished, and distilled water ( (Liquid temperature: 25 ° C.), and polished while dropping the polishing liquid at a rate of 1 liter / min. After polishing, the surface of the quartz glass substrate was observed with a microscope (manufactured by OLYMPUS, model: BH-2). In the evaluation, ○ indicates that the surface was extremely smooth and had no scratches, etc., and X indicates that the surface could not be polished without being smooth.

-Durability of the molded body-The polishing test was continuously performed, the molded body was taken out every hour, and the surface condition was visually observed, and the presence or absence of breakage such as cracks, cracks, chips, etc. was observed. . At the time of evaluation, the time until the molded article was damaged was examined.

<Manufacture and Evaluation of Polished Molded Body> Example 1 A ceria raw material powder was prepared as follows. Cerium carbonate hydrate (manufactured by ALDRICH, 99.9) using a planetary mill.
%) Was dispersed in distilled water to obtain a suspension. Aqueous hydrogen peroxide (about 35%) was added dropwise while stirring the suspension, and stirring was continued for 1 hour after completion of the addition. Thereafter, the temperature was raised to 90 ° C. in a water bath, and stirring was further continued for 1 hour, then cooled to room temperature, and solid-liquid separated by a centrifugal separator.
Dried for hours. The obtained solid content was converted into 600 using a firing furnace.
Heating was performed at 1 ° C. for 1 hour to obtain a white powder. The obtained white powder was analyzed using an X-ray diffractometer (manufactured by Mac Science, model: M
XP-3) confirmed that it was a ceria single phase. The ceria powder had a BET specific surface area of 49 m ^2.
/ G, average particle diameter was 0.3 μm.

An acrylic binder (manufactured by Chuo Rika Kogyo Co., Ltd., Ricabond SA-) was added to the ceria raw material powder as an additive.
200) and stearic acid emulsion (manufactured by Chukyo Yushi,
Cellosol 920) was mixed at a weight ratio of raw material powder: acrylic binder (in terms of solid content): stearic acid emulsion (in terms of solid content): water = 100: 40: 2: 520 to form a slurry. Granulated powder is prepared from this slurry using a spray drier (manufactured by Okawara Kakoki Co., Ltd., model: LT-8), and press-formed using a hydraulic press (pressure:
100 kg / cm ² ) to obtain a ceria compact, which was degreased by holding it at 400 ° C. for 2 hours in a firing furnace (manufactured by Koyo Lindberg Co., model: 51668).
And heated for 2 hours to obtain a molded body for polishing. This was evaluated by the evaluation method described above. Table 1 shows, as the obtained results, the bulk density, the BET specific surface area, the average particle size, the polishing test results and the durability test results of the obtained polishing molded bodies.

[0049]

[Table 1]

Example 2 Ceria raw material powder (Mitsuwa Chemicals, purity 99.9%, B
ET specific surface area of 3.6 m ² / g, average particle size of 2 μm) and an acrylic binder (manufactured by Chuo Rika Kogyo Co., Ltd., Ricabond SA-200) and a stearic acid emulsion (manufactured by Chukyo Yushi, Cellosol 920) as additives. Acrylic binder (solid content conversion): stearic acid emulsion (solid content conversion): moisture = 100: 40: 2: 382
And mixed to obtain a slurry. Spray dryer (Okawara Kakoki, Model: LT-8)
Was used to prepare a granulated powder, and water was sufficiently removed in a desiccator. Potato starch (manufactured by Kishida Chemical Co., Ltd.) was mixed with the dried granulated powder in a volume ratio of dried granulated powder: potato starch = 2: 1 to obtain a raw material powder for molding. This raw material powder was press-molded (pressure: 100 kg / cm ² ) using a hydraulic press to obtain a ceria molded body. This was degreased by holding it at 400 ° C. for 2 hours in a firing furnace, heated to 1200 ° C. as it was, and fired for 2 hours to obtain a molded body for polishing. This was evaluated in the same manner as in Example 1 and shown in Table 1.

Comparative Example 1 An acrylic binder (manufactured by Chuo Rika Kogyo, Ricabond SA-) was added to the ceria raw material powder used in Example 1 as an additive.
200) and stearic acid emulsion (manufactured by Chukyo Yushi,
Cellosol 920) was mixed at a weight ratio of raw material powder: acrylic binder (in terms of solid content): stearic acid emulsion (in terms of solid content): water = 100: 40: 2: 520 to form a slurry. Granulated powder is prepared from this slurry using a spray drier (manufactured by Okawara Kakoki Co., Ltd., model: LT-8), and press-formed using a hydraulic press (pressure:
100 kg / cm ² ) to obtain a ceria compact, which was degreased by holding it at 400 ° C. for 2 hours in a firing furnace (manufactured by Koyo Lindberg Co., model: 51668).
And heated for 2 hours to obtain a molded body for polishing. This was evaluated in the same manner as in Example 1 and shown in Table 1.

Comparative Example 2 A suede-type polishing pad (SURFIN 018-3, manufactured by Fujimi Incorporated) was attached to a rotating platen (diameter 360 mm) of a high-speed lens polishing apparatus, and the platen was polished on the platen at a rotation speed of 100 rpm. Material pressing force 15
Under the condition of 0 g / cm ^2, a quartz glass substrate is used as a material to be polished, and the ceria fine powder described in Example 1 is distilled as an abrasive so that the ceria (cerium oxide) content becomes 20% by weight. Polishing liquid prepared by adding water (liquid temperature: 2
(5 ° C.) at a rate of 1 liter / min. Table 1 shows the surface accuracy measurement results as the obtained results.

When the results of Examples 1 and 2 and Comparative Example 1 were compared, it was found that if the polishing was performed using a molded article for polishing having the characteristics as in Comparative Example 1, the polishing could not be performed well.

On the other hand, when the results of Examples 1 and 2 and Comparative Example 2 are compared, a polishing molded body applicable to polishing can be obtained by performing polishing using the polishing molded body of the present invention. Moreover, it was found that the surface accuracy of the material to be polished was about the same as that obtained by the conventional polishing method.

<Evaluation of Polishing Waste Liquid> Example 3 The polishing molded body obtained in Example 1 was polished by the method described in the polishing test. For polishing waste liquid,
The turbidity of the generated waste liquid is measured with a spectrophotometer (manufactured by JASCO, model: U
best-55) and a wavelength of 60 with respect to purified water.
It was evaluated by the transmittance at 0 nm. Table 2 shows the results.
It was shown to. When the transmittance is high, it indicates that the amount of free abrasive grains in the polishing waste liquid is small, and when it is low, it indicates that the amount is large.

[0056]

[Table 2]

Example 4 A waste polishing liquid was evaluated in the same manner as in Example 3 except that the molded article for polishing obtained in Example 2 was used.

Comparative Example 3 The polishing waste liquid obtained in the polishing test performed in Comparative Example 2 was evaluated in the same manner as in Example 3, and the results are shown in Table 2.

When the above Examples 3 and 4 are compared with Comparative Example 3, polishing using the polishing table of the present invention results in a higher polishing waste liquid transmittance than the conventional method. It is understood that the amount of free abrasive grains in the waste liquid is extremely small.

[0060]

According to the present invention, almost no polishing waste liquid containing a large amount of free abrasive grains is generated during the polishing process, and the silicon wafer can be as good as the conventional method.
It is possible to polish a substrate material such as an oxide substrate,
Further, since the molded body for polishing in the polishing treatment has durability, it is useful for the polishing process.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI B24D 3/32 B24D 3/32 H01L 21/304 622 H01L 21/304 622B 622F

Claims (4)

[Claims] 1. A mainly consists ceria (cerium oxide), a bulk density of not more than 0.7 g / cm ³ or more 5.0 g / cm ^3, BET specific surface area of 2m ² / g or more 200 meters ² /
g and a mean particle size of 0.001 μm or more and 0.5 μm or less. 2. A polishing platen comprising the molded article for polishing according to claim 1 and auxiliary components. 3. A polishing method characterized in that a material to be polished is pressed against the polishing platen according to claim 2 and is rubbed. 4. A polishing waste liquid which is polished without using free abrasive grains.
The polishing method according to claim 3, wherein the transmittance at 00 nm is 10% or more of the transmittance of water.