JPH11104952A - Formed body for polishing, manufacture thereof, ruler table for polishing, and polishing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a formed body for polishing and manufacture thereof and a ruler table for polishing and polishing method which can reduce a waste fluid problem by the use of a polishing liquid excluding such separated grains and carry out the finish polishing with the same extent as usual method and polish effectively by improving the durability of a polishing process and polishing speed much more, in a process for polishing substrate materials such as a silicon wafer, oxide substrate and compound semi-conductor substrate. SOLUTION: This formed body is composed of mainly silica (silicon dioxide), a bulk density is 0.2-1.5 g/cm<3> , BET ratio surface area is 10-400 m<2> /g, average grain diameter is 0.001-0.5 μm, fine hole mode diameter is 0.01-0.3 μm, fine hole median diameter is 0.01-0.3 μm, integrated whole fine hole volume is 0.3-4 cm<3> /g and the integrated fine hole volume of the fine hole, whose fine hole diameter is 1 μm or more, is 20-70% of the integrated whole fine hole volume of the formed body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molded body for polishing suitable for polishing substrate materials such as silicon wafers, oxide substrates such as lithium niobate and lithium tantalate, and compound semiconductor substrates, and a method for producing the same. The present invention relates to a polishing table and a polishing method.

[0002]

2. Description of the Related Art Conventionally, silicon wafers, oxide substrates,
In the polishing process of a substrate material such as a compound semiconductor substrate, a non-woven fabric type or a swab is prepared by continuously flowing a polishing liquid prepared by mixing free abrasive grains such as colloidal silica with a chemical such as potassium hydroxide on the surface of the substrate material or the like. Finished by polishing with a polishing pad such as Ade type,
For example, JP-A-5-154760, JP-A-7-32659
No. 7 discloses that a silicon wafer is polished using various polishing agents and polishing cloths. However, in the case of using such a method, a large amount of free abrasive grains is used, so that a polishing waste liquid containing a large amount of free abrasive grains is generated. Should be improved considering the impact of
In addition, in the polishing process, the performance of the polishing cloth such as clogging is deteriorated in a short time, so that it is necessary to replace the polishing cloth with a new one. Further, the polishing speed is not high, and the polishing process is performed more efficiently. There was also a problem in terms of.

[0003]

As described above, when the polishing is performed by the conventional method, there is a problem that a polishing liquid containing a large amount of free abrasive grains such as colloidal silica is discarded. Further, it has been desired to improve the efficiency of the polishing process, and the present invention has been made in view of such problems. The aim is to reduce the problem of waste liquid by using a polishing liquid that does not contain such free abrasive grains in the process of polishing substrate materials such as silicon wafers, oxide substrates, and compound semiconductor substrates. The present invention provides a molded article for polishing, which has the same level of polishing finish as the method described above, has durability in the polishing process, and can further improve the polishing rate, so that the polishing operation can be made more efficient, a manufacturing method thereof, a polishing platen and a polishing method. Is to do.

[0004]

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, when forming the powder using the ultrafine silica powder, the granulated raw material powder and the pore-forming agent were mixed. The obtained silica powder was molded and processed to obtain a molded body for polishing having characteristics within a certain range, and the following findings were found to be excellent by incorporating this into a polishing platen and polishing the substrate material and the like. Was.

1) During polishing, the surface of the molded article for polishing is
Since the surface is roughened by the ultrafine powder of silica, which is the raw material, and the material to be polished comes into direct contact, polishing of the substrate material and the like is performed using a polishing liquid that does not contain free abrasive grains such as colloidal silica. It can be applied to the processing process, and at that time, the particles of the molded body are very little dropped,
The problem of waste liquid is reduced.

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

[0007] 3) The finish of the polished material is equal to or more than that of the conventional method using a polishing cloth, and the polishing rate is equal to or more than that of the conventional method. .

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

In particular, by setting the pore structure of the molded article for polishing to a characteristic within a certain range, the performance of the molded article for polishing mainly composed of silica is further improved, that is, the polishing speed is improved and the polishing is performed. They have found that work efficiency can be improved, and have completed the present invention.

Hereinafter, the present invention will be described in detail.

First, the molded article for polishing according to the present invention will be described.

The abrasive compact used in the present invention is mainly composed of silica (silicon dioxide), has a bulk density of 0.2 to 1.5 g / cm ³ and a BET specific surface area of 10 to 10.
400 m ² / g, average particle size 0.001 to 0.5 μ
m, cumulative total pore volume is 0.3 to ⁴ cm ³ / g, pore diameter 1
The cumulative pore volume of the pores larger than μm is 20 to 70% of the cumulative total pore volume of the molded article for polishing.

Here, mainly silica substantially means a silica component in a silica powder used as a raw material of the molded article for polishing of the present invention, and a molded article is produced using the silica powder. Additives such as binders used at that time are eventually lost by a process such as firing or sintering. Therefore, the silica component in the abrasive compact has a composition based on the component of the silica powder that is the raw material.
In addition, for additives such as a binder used when manufacturing a molded body, for example, the presence or absence thereof can be confirmed by an analytical method such as suggestive thermogravimetric analysis, and usually,
When heated to about 500 to 600 ° C., additives such as a binder almost disappear.

Further, the composition of the silica powder as a raw material mainly includes silica, that is, a silica component having a total amount of 9%.
Those having 0% by weight or more are preferably used.
Examples of the type include dry silica and wet silica. The silica component as used herein means a silica content, and the silica component, impurities, and loss on ignition (Loss of loss) after heating the silica powder at 105 ° C. for 2 hours.
(Ig loss, hereinafter referred to as "Ig loss"). Therefore,
Excluding the loss on ignition, the silica powder as the raw material is 97% by weight or more of the total amount as the silica component. If the silica component falls below the above range, the material to be polished (hereinafter, referred to as “material to be polished”) is polished when the polishing is performed using the finally obtained molded body for polishing. In some cases, contamination may occur due to impurities therein, or a defect may occur in the material to be polished during polishing.

The bulk density of the molded article for polishing is in the range of 0.2 to 1.5 g / cm ^{3 in} order to maintain the shape of the molded article for polishing and obtain a smooth surface of the material to be polished. Is preferable, and furthermore, in order to make it difficult to lower the durability and the polishing rate at the time of polishing using the molded article for polishing, 0.4
The range is preferably from 0.9 g / cm ^{3 to} 0.9 g / cm ³ . The bulk density is 0.
If it is less than 2 g / cm ³ , the durability is reduced and the shape retention is so poor that the shape cannot be maintained.
If it exceeds / cm ³ , defects on the surface of the material to be polished cannot be ignored, and a smooth surface cannot be obtained, which is not preferable.

The BET specific surface area of the molded article for polishing is preferably in the range of 10 to 400 m ² / g. Further, in order to reduce the frequency of processing such as dressing of the polished surface of the molded article for polishing during polishing. The range of -150 m < ² > / g is preferable. When the BET specific surface area exceeds 400 m ² / g, the shape retention of the molded article is deteriorated so that the shape of the molded body cannot be maintained. When the BET specific surface area is less than 10 m ² / g, defects on the surface of the material to be polished cannot be ignored, so It is not preferable because it cannot be obtained.

The average particle size of the abrasive compact is preferably in the range of 0.001 to 0.5 μm in order to facilitate molding into a porous body and obtain a smooth surface of the material to be polished. In order to reduce the frequency of processing such as dressing of the polished surface of the molded article for polishing during polishing, 0.01
The range of about 0.5 μm is preferable. Average particle size 0.00
When the diameter is smaller than 1 μm, the primary particle diameter of the raw material powder becomes 0.1.
It becomes smaller than 001 μm, and it becomes extremely difficult to mold into a porous body.

Further, it is preferable that the cumulative total pore volume of the molded article for polishing having the above characteristics is in the range of 0.3 to ⁴ cm ³ / g. The pore size distribution is as follows.
The cumulative pore volume of pores larger than μm is preferably in the range of 20 to 70% of the total pore volume of the molded body, and more preferably 20 to 70%.
A range of 50% is preferred, and a range of 20 to 30% is particularly preferred. The pore mode diameter is 0.01-0.3μ
m, the pore median diameter is 0.01 μm to 0.3 μm
m is preferable. The reasons are as follows: a) in order to maintain the shape of the polishing body during polishing; b) to obtain a smooth surface of the material to be polished; This is to improve the effect of preventing cracks and the like, d) to reduce clogging during polishing, and the like.

In this specification, the pore mode diameter means the pore diameter at which the differential value in the differential pore diameter distribution is maximum, and the median pore diameter is the integrated pore volume in the integrated pore diameter distribution. It means the pore diameter with respect to the median of the range between the maximum value and the minimum value. The pore mode diameter and the pore median diameter are based on volume.

Next, a method for producing a molded article for polishing used in the present invention will be described.

Hereinafter, the present invention will be described in detail according to manufacturing steps.

The characteristics of the powder mainly composed of silica used as a raw material powder are not particularly limited as long as a molded body having good shape retention and being applicable to the polishing process can be obtained. The raw material powder having the characteristics described in (1) is used.

That is, the silica powder as a raw material is mainly composed of silica and has a BET specific surface area of 25 to 400 m.
² / g, the average particle diameter is 0.5 to 50 μm, and when the primary particle diameter calculated from the BET specific surface area is Db (μm) and the average particle diameter is Ds (μm), these relationships are 1 ≦
Ds / Db ≦ 4000, powder bulk density is 2
It is preferably from 0 to 140 g / L.

Here, as the composition of the silica powder as a raw material, the one having a silica component of 90% by weight or more of the total amount as described above is preferably used.

The silica powder has a BET specific surface area of 2
The range is preferably from 5 to 400 m ² / g, and more preferably from 25 to 200 m ² / g in order to easily maintain the polishing rate at the time of polishing the obtained molded article for polishing. 400
If it is more than m ² / g, the formability may be deteriorated and it may be difficult to obtain a molded body for polishing, and if it is less than 25 m ² / g, a defect may occur in the material to be polished during polishing.

The average particle size of the silica powder is 0.5
When the thickness is less than 0.5 μm, the moldability is deteriorated, and it may be difficult to obtain a molded body for polishing. May be caused.

When the primary particle diameter calculated from the BET specific surface area is Db (μm) and the average particle diameter is Ds (μm), these relations may be 1 ≦ Ds / Db ≦ 4000. preferable. When Ds / Db is less than 1, it means that the primary particle size is smaller than the average particle size, and this is not possible. Ds / D
If the value of b exceeds 4,000, the primary particle diameter tends to aggregate, and molding may be difficult.

Here, as a method for calculating the primary particle diameter from the BET specific surface area, the primary particles can be obtained by the following equation (1), assuming that the primary particles are spherical.

Db = 6 / (S × 2.2) (1) In the formula, S represents a BET specific surface area (unit: m ² / g), Db represents a primary particle diameter (unit: μm), and Calculated with a theoretical density of 2.2 g / cm ³ .

The bulk density of the powder is preferably 20 to 140 g / L, and if it is less than 20 g / L, molding may be difficult. If it is more than 140 g / L, defects may occur in the material to be polished during polishing. There is.

At this time, the compressive strength of the abrasive compact naturally becomes 1 kg / cm ² or more.

Next, the raw material silica powder having such powder characteristics is mixed with a binder, and the mixture is further granulated. After that, the granulated powder is mixed with a pore-forming agent so as not to be broken, and then molded. The formability is improved by mixing with the silica powder and granulating, and further, the obtained granulated powder is mixed with the pore forming agent to obtain a silica molded body reflecting the particle size of the pore forming agent, and is used for polishing. Since it becomes easy to control the pore structure in the compact, a compact for polishing that can improve the polishing rate during polishing is obtained. In the above process, the granulated powder may be temporarily transferred and stored before mixing with the pore-forming agent.

In the above-mentioned production process, the method of mixing the silica powder and the binder is not particularly limited. However, in order to sufficiently cover the surface of the silica raw material powder, a water-soluble binder is usually used with water or the like as a solvent. And silica powder are mixed. At this time, they can be mixed by a ball mill or the like using balls.

The mixed powder thus mixed with the binder is subjected to a granulating operation in order to improve the moldability.
The granulation method is not particularly limited. However, the mixed powder is spray-dried directly in a slurry state by a spray dryer or the like, or the powder is dried by a known method and then granulated by a rolling method or the like. Can be.

At this time, it is preferable that 50% or more of the granulated powder has a particle size of 5 to 300 μm on a weight basis.
By distributing the particle size of the granulated powder in this way, the moldability is improved, and the uniform particle size facilitates uniform mixing in the subsequent mixing with the pore-forming agent. If it is out of this range, if the particle size of the powder is too fine, the fluidity of the powder is reduced, for example, the filling of the powder in the mold becomes worse during press molding, or when the pressure is released after the completion of molding. Air tends to remain in the molded body with a decrease in fluidity, and defects such as lamination may easily occur.If the particle size of the powder is too coarse, for example, the filling of the powder into the mold during press molding is poor. And the moldability may be deteriorated. In addition, this particle size can be usually known by observing with an optical microscope or measuring with a particle size distribution measuring device.

The mixing amount of the binder is not particularly limited, but may be any amount which does not hinder the molding operation and the like. Since the BET specific surface area of the silica powder is large, (the volume of the silica powder) It is preferable to add the binder so that (volume) :( volume of binder) = about 90:10 to 30:70. By doing so, the periphery of the primary particles can be wetted with the binder, and the moldability can be improved.

The kind of the binder can be used without any particular limitation as long as it does not hinder the granulation operation. In general, a binder, a plasticizer, a lubricant and the like can be used. Polyolefin resins, waxes, lower fatty acids such as stearic acid, higher alcohols such as stearyl alcohol, and the like,
These can be used alone or in combination of two or more.

Next, the granulated powder and the pore-forming agent are mixed.
The mixing method is not particularly limited as long as it can be mixed with the pore-forming agent without breaking the granulated powder. For example, dry mixing using a V-type mixer can be exemplified. here,
Not breaking the granulated powder means that the particle size distribution of the granulated powder does not change significantly before and after mixing with the pore forming agent,
When the particle size of the granulated powder before mixing the pore-forming agent is 5 to 300 μm in 50% or more of the whole by weight, the particle size of the granulated powder after mixing the pore-forming agent is the whole 40% or more indicates that the thickness is 5 to 300 μm. This particle size can be known usually by observing with an optical microscope or measuring with a particle size distribution measuring device.

Thus, by reducing the change in the particle size distribution of the granulated powder before and after mixing with the pore-forming agent, the particle size of the pore-forming agent before mixing is reflected in the pore size distribution of the molded article for polishing. Because of this, the pore size distribution can be easily controlled, and a pore structure suitable for a molded article for polishing can be obtained. As a result of mixing in this manner, the pore structure of the polishing compact finally obtained is such that the sum of the pore volumes occupied by pores having a pore diameter of 1 μm or more is 20 to 70% of the total pore volume. And the polishing rate can be improved in the actual polishing process. This ratio can be controlled by the amount of the pore-forming agent described below.

The amount of the pore-forming agent is not particularly limited as long as the molded article for polishing having the above-mentioned pore structure can be obtained, but is usually (weight of the pore-forming agent) / (weight of the granulated powder). ) =
The ratio is preferably in the range of 2/1 to 1/10.
If the ratio is less than 1/10, the effect of mixing the pore-forming agent may be reduced. If the ratio is more than 2/1, the molded article for polishing may become brittle and may be difficult to be put to practical use.

The average particle size of the pore-forming agent is 0.1 to 2
A range of 00 μm is preferred. When the average particle size is smaller than 0.1 μm, there is no large difference from the pore size distribution when molded without using a pore-forming agent, and the effect of introducing a large pore by mixing the pore-forming agent is lost. There is 2
If it is larger than 00 μm, molding may be difficult.

Further, the pore-forming agent is burnt, thermally decomposed and vaporized by heating to evaporate and disappear, and a hole is formed in the molded article for polishing.
00-900 degreeC is preferable. If the temperature is lower than 100 ° C., it may be difficult to handle the material, but it may be solid at room temperature. If the temperature exceeds 900 ° C., shrinkage of the silica molded article may occur. In particular, if the temperature exceeds about 950 ° C., rapid shrinkage occurs. Is not preferred because it may cause

Examples 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-vinyl acetate copolymer, ethylene Powder of olefin resin such as ethyl acrylate copolymer, polystyrene powder, powder of lower fatty acid such as stearic acid,
Potato starch, corn starch, ethyl cellulose, carbon powder and the like can be exemplified.

The powder specific gravity of the pore-forming agent is preferably closer to silica powder because it is easily mixed with silica powder, but the range of density is not particularly limited.

The method of molding the mixed powder obtained by mixing the granulated powder and the pore-forming agent is not particularly limited, and examples thereof include a method of molding by applying pressure and a so-called slip casting method of casting as a slurry. For example, when molding under pressure, a molding method such as press molding can be exemplified, and the pressure condition is usually a pressure of 5 kg / cm ² or more in order to maintain the shape of the obtained silica molded body,
Pressures of 10 kg / cm ² or more are more effective.

Examples of a method for processing the silica molded body into a molded body for polishing include a method using heat degreasing, heating and baking, machining, and the like, and a processing method capable of imparting a strength that can be used in a polishing operation as a molded body for polishing. If it is not particularly limited, in order to improve moldability, an organic binder such as a binder is added before molding, and a pore-forming agent is also added. It is preferable to degrease before firing.

The method of degreasing 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 or helium. At this time, the pressure of the atmosphere gas can be reduced, reduced pressure, or reduced pressure. Similarly, in order to improve the moldability, moisture may be added and then dried before the firing operation.

Next, since the molded body from which the binder and the pore-forming agent have been removed is generally brittle in terms of strength, in order to increase the strength and improve the durability during polishing, for example, It is preferable to perform baking by heating, and other known methods can also be used.

Thus, the molded article for polishing used in the present invention is manufactured. Next, the molded article for polishing is assembled as a polishing platen, and the polishing is performed using the same. Will be described.

First, a polishing platen is formed by using a polishing compact and a polishing accessory part. Here, ancillary parts are structures of various shapes constituting a polishing platen, and a polishing platen is arranged and fixed to the auxiliary parts by various methods to form a polishing platen. It is formed. As a fixing method of both, any method can be used without limitation as long as the method can achieve the object of the present invention, such as a method of bonding and fixing using an adhesive, a method of forming irregularities on the accessory parts, and a method of embedding in the fixing place. .

The number of the molded bodies for polishing when fixing the molded bodies for polishing to the auxiliary parts for polishing may be one, two or more, and more preferably two or more. The reason is that i) 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 using two or more polishing compacts, the polishing liquid can be discharged from the gap between the polishing compacts. Also,
When one is used, it is preferable to provide an appropriate groove structure capable of discharging the polishing liquid on the polishing surface side of the molded body.
ii) Further, when a polishing platen is formed by using two or more polishing compacts, the contact with the material to be polished is improved,
Polishing can be performed efficiently without biasing the polishing rate over the entire surface of the material to be polished.

The shape of the abrasive compact to be used is not particularly limited, and examples thereof include columnar pellets such as columnar pellets, quadrangular columnar pellets, and triangular columnar pellets. The size is not particularly limited as long as it is within a range usually used, and is determined according to the size of an accessory part for incorporating a molded body for polishing in a polishing table.

Although the size is not particularly limited, it is practically preferable that one side be within a range of 5 mm square to 100 mm square. For example, a cylindrical pellet has a diameter of 5 to 100 mm, and a square pillar pellet has a diameter of 5 to 1 mm.
This is one side within the range of 00 mm. 5m on each side
Even if it is smaller than the range of m-square, it has a sufficient function as a polishing surface plate, but is impractical because the number of arrangements becomes very large. Even if one side is larger than the range of 100 mm square, it has a sufficient function as a polishing platen, but the effect of arranging a plurality of the above-mentioned polishing compacts is reduced.

The thickness of the shaped body for polishing is not particularly limited, but is preferably in the range of 3 to 10 mm. Even when the thickness is smaller than 3 mm, it has a sufficient function as a polishing plate, but the above range is preferable in consideration of practicality. Even when the thickness is larger than 10 mm, the surface has a sufficient function as a polishing plate, but the above range is preferable in consideration of practicality.

The manner of arrangement is not particularly limited as long as the molded bodies for polishing can be used in the polishing process and are naturally arranged over the entire surface of a place (for example, a rotating platen of a polishing apparatus) which must be arranged. It may be random, but it is arranged symmetrically with respect to the center line of the polishing platen so that the polishing efficiency is not affected by the polishing position of the material to be polished. Is more preferred.

The number of the above-mentioned abrasive compacts to be arranged depends on the size of each of the abrasive compacts and a place where the abrasive compacts must be arranged in order to be usable in the polishing process (for example, the rotation of the polishing apparatus). Although it cannot be unconditionally limited by the size of the platen or the like, the polishing surface of the polishing molded body with respect to the total area of the place where the molded bodies for polishing are to be arranged (the surface that comes into contact with the material to be polished during polishing, It is preferable that it is 95% or less in terms of the ratio of the total area (hereinafter the same). The fact that this ratio exceeds 95% is not so different from the case of using one large abrasive compact,
The effect of arranging a plurality of polishing compacts to form a polishing platen is reduced. The lower limit of this ratio is not particularly limited, but if it is too small, it means that the total area of the polished surface of the molded article for polishing is small, and about 30% or more is practical.

When a plurality of abrasive compacts are arranged, a method of fixing the abrasive compacts to a place where the abrasive compacts must be naturally arranged (for example, a rotating platen of a polishing apparatus) in order to be used in the polishing process is as follows. The fixing method is not particularly limited as long as the forming method for polishing can be used in the polishing process, but examples thereof include a method of individually fixing with an adhesive or the like, a method of embedding in a fixing place, and the like. .

Further, the molded article for polishing obtained by the method of the present invention can be incorporated in a polishing table and used in a polishing process. If so, its properties, polishing conditions, use of a polishing liquid, and the like are not particularly limited. For example, when a polishing liquid is used, an alkaline solution such as an aqueous solution of potassium hydroxide can be used. Here, the surface plate is used for directly contacting and polishing the material to be polished, has sufficient strength in a polishing process, and may have a performance capable of polishing the material to be polished. . Therefore, not only does it have the same shape as the material to be polished,
It may have a non-planar shape if necessary. For example, the shape may be a flat plate, a disk having a non-planar surface such as a convex surface or a concave surface, a ring shape, a cylindrical shape, or the like.

Also, in the polishing method of the present invention, the durability is improved, the stable polishing performance can be maintained, and the frequency of replacement can be reduced by using the polishing article of the present invention without using the polishing cloth. In addition, the frequency of interruption of the polishing work due to replacement of the polishing cloth due to performance deterioration of the polishing cloth, which is observed in the conventional method during polishing, can be reduced, and the efficiency of the polishing work can be improved. Further, by controlling the pore structure by the production method of the present invention, there is no need for dressing to improve clogging until the molded article for polishing is used up, or the molding for polishing is extremely suppressed in frequency of dressing. The body is obtained. In addition, the polishing waste liquid containing free abrasive grains generated by the conventional method using an abrasive can be polished without using free abrasive grains by using the molded article for polishing manufactured by the manufacturing method of the present invention. Therefore, free abrasive grains in the polishing waste liquid are eliminated, and the problem of waste liquid treatment is reduced. Even in the case of using a polishing liquid containing free abrasive grains, the problem of waste liquid treatment can be reduced because the polishing can be performed at a concentration of the free abrasive grains which is lower than that of the conventional method. For example, it can be confirmed that when the polishing waste liquid is irradiated with light, the transmittance becomes higher than that in the conventional method, so that unnecessary free abrasive grains are not mixed into the polishing waste liquid. In consideration of such a problem of the polishing waste liquid, it is preferable that the transmittance of the polishing waste liquid at a wavelength of 600 nm be 10% or more of water. In addition, as a matter of course, it is also possible to perform polishing using a polishing liquid containing free abrasive grains as in the case of the conventional polishing method using a polishing cloth.

Examples of uses of the polishing molded body having such characteristics and the polishing platen provided with the polishing molded body include a silicon wafer, a compound semiconductor substrate such as gallium phosphide and gallium arsenide, lithium niobate and lithium tantalate. ,
It can be used for polishing an oxide substrate such as lithium borate, a substrate material such as a quartz glass substrate, quartz glass, a metal material, and a stone material such as a building.

[0061]

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.

-Silica Content- The water content and the loss on ignition of the silica powder (Loss of Ig)
Nition, hereinafter referred to as “Ig loss”), Al
₂ O ₃ , Fe ₂ O ₃ , TiO ₂ , CaO, MgO, and Na ₂ O were measured by the following methods. Ig loss, Al ₂ O ₃ , Fe ₂ O ₃ , TiO ₂ , CaO, MgO, from the weight (water-free content) of the remainder of the silica powder excluding the water content
The weight obtained by subtracting the total weight of Na ₂ O was defined as the silica content, and the weight was calculated in weight%.

The water content was determined from the weight change before and after the silica powder was heated at 105 ° C. for 2 hours.

The Ig loss was determined by heating the silica powder at 105 ° C. for 2 hours to remove water, and
Heat treatment was performed at 00 ° C., and the weight change before and after the treatment was determined.

Al ₂ O ₃ , Fe ₂ O ₃ , TiO ₂ , CaO,
The amounts of MgO and Na ₂ O were determined by heating a silica powder at 105 ° C. for 2 hours to remove water, dissolving the same, and measuring by ICP method.

The silica content of the molded article for polishing was measured using a differential thermogravimetric analyzer (Rigaku Corporation, model: TAS-100) at a heating rate of 10 ° C. /
When measured in minutes, no decrease in weight was observed in the range from room temperature to 1000 ° C., and additives such as binders used when manufacturing a molded body using silica powder had disappeared. Was confirmed.

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

-Powder bulk density- According to the stationary method of the apparent density test method of JIS-K-5101, the powder is dispersed and dropped through a sieve having an opening of 0.50 mm, received in a 30.0 mL stainless steel cylinder, At the peak, it was rubbed off with a linear spatula, the weight in the cylinder was measured, and it was determined by the following equation (2).

E = W / 30 (2) where E is powder bulk density (unit: g / mL), W is powder weight in cylinder (unit: g), and 30 is volume in cylinder (unit: mL). Yes, the unit of powder bulk density is arbitrarily converted. In this specification, the measured apparent density is described as powder bulk density.

[Average Particle Size] A part of the abrasive compact was subjected to scanning electron microscope ISI DS
Observed with -130 (manufactured by Akashi Seisakusho), and determined by the intercept method considering only the silica particle portion.

BET Specific Surface Area After grinding the molded body for polishing, MONOSORB (QUA
(Antachrom Co., Ltd.) using the BET one-point method.

-Pore Structure- The abrasive compact was prepared by using a mercury porosimeter (manufactured by Shimadzu Corporation).
Using a pore sizer 9320) and a mercury intrusion method.
It was measured in a pressure range of 70 MPa. The measurement value obtained with a mercury porosimeter is obtained by applying pressure to mercury and injecting mercury into a sample having pores, and the relationship between the pressure and the cumulative volume of mercury that has entered. That is, the pressure for mercury to enter a pore having a certain diameter has a Washburn equation, and by using this equation, the relationship between the injection pressure and the integrated volume of mercury that has penetrated is larger than the diameter of the pore and its diameter. It can be determined as the relationship of the volume of mercury that has penetrated into pores having a large diameter. Then, the volume of the infiltrated mercury is divided by the density of the mercury to show the volume of pores larger than the pore diameter. The relationship between the pore diameter and the pore volume is usually corrected as necessary, such as the surface tension of mercury, the contact angle, and the mercury head coming from the structure of the measuring device. The following values (volume basis) are obtained from the relationship between the pore diameter obtained by the mercury porosimeter and the cumulative volume of the pores. The pore mode diameter is the pore diameter at which the differential value in the differential pore distribution is maximum, that is, the pore diameter corresponding to the highest value of the differential pore volume in the differential pore diameter distribution curve shown in FIG. (Denoted by A). The pore median diameter is the pore diameter corresponding to the median of the minimum and maximum values of the integrated total pore volume in the integrated pore diameter distribution, that is, the integral total fineness of the integrated pore diameter distribution curve shown in FIG. It means the pore diameter corresponding to the median value (1 / h) of the maximum value (h) and the minimum value (0 in FIG. 2) of the pore volume.

Compressive Strength In accordance with JIS-R-1608, a test piece (10 mm × 10 mm × 5 mm (thickness)) of a molded body for polishing was used by using a Shimadzu Autograph IS-10T (manufactured by Shimadzu Corporation). The measurement was performed with a load applied at a crosshead speed of 0.5 mm / min.

~ Average particle diameter of powder ~ Ultrafine silica powder was used as a sample, and COULTER LS
130 (manufactured by COULTER ELECTRONICS) using a liquid module. Measurements are on a volume basis.

Polishing Test A cylindrical test piece of a molded body for polishing having a diameter of 25 mm and a thickness of 5 mm was prepared, and was rotated on a rotating platen (diameter 36) of a high-speed lens polishing apparatus.
0 mm) to flatten the surface of the molded article. Under the conditions of a platen rotation speed of 100 rpm and a processing pressure of the material to be polished on the platen of 118 g / cm ² , commercially available colloidal silica (Fujimi Incorporated) was used by using six pieces of lithium tantalate having a diameter of 3 inches as the material to be polished. DO, COM
POL80) was prepared to have a silica (silicon dioxide) content of 8% by weight (liquid temperature: 25 ° C., pH = 1).
Using 2), the polishing liquid was dropped at a rate of 100 mL / min and polished while being circulated. After polishing, the surface of the lithium tantalate substrate was examined 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.

The polishing rate was calculated by measuring the thickness of the lithium tantalate substrate before and after the polishing test with a dial gauge. That is, Examples 1-4 and Comparative Example 3
For one polishing test, the thickness at any 10 points on the surface to be polished of the lithium tantalate substrate as the material to be polished is measured intermittently with the progress of the test during one batch of the polishing test, and the polishing rate per 8 hours is obtained. The average value was defined as the polishing rate per batch, and the average value and the standard deviation of the polishing rate for each batch were determined. In Comparative Example 2, the average value of the results of five measurements was used as the polishing rate.

-Surface Accuracy- The surface accuracy of the material to be polished after the polishing treatment was evaluated using a universal surface shape measuring instrument SE-3C (manufactured by Kosaka Laboratories). The evaluation was performed under the conditions of a center line average roughness (Ra) and a maximum height (Rmax) of a cutoff value of 0.8 mm or more and a measurement length of 2.5 mm. Here, Ra means the center line average roughness, and a portion of the measured length (represented by L) is extracted from the roughness curve in the direction of the center line, and the center line of the extracted portion is defined by the X axis and the vertical axis. The direction of magnification is the Y axis, and the roughness curve is y = f
When expressed by (x), the value obtained by the following equation (3) is expressed in units of micrometers (μm).

[0078]

(Equation 1)

Further, Rmax means the maximum height. When two straight lines parallel to a parallel line of a portion extracted by the reference length from the cross-sectional curve sandwich the extracted portion, the interval between the two straight lines is defined by the cross-sectional curve. Is measured in the direction of the vertical magnification, and this value is expressed in units of micrometers (μm).

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

<Manufacture and Evaluation of Polished Molded Product> Example 1 A raw material powder of precipitated silica obtained by a wet method and having the characteristics shown in Table 1 was press-formed using a hydraulic press (pressure: 10).
kg / cm ² ) to obtain a silica molded body. This was placed in a firing furnace (manufactured by Koyo Lindberg, model: 51668) for 70 minutes.
It was baked at 0 ° C. for 2 hours to obtain a molded body for polishing. This was evaluated by the evaluation method described above. Tables 2 and 3 show the obtained results as the bulk density, BET specific surface area, average particle diameter, compressive strength, measured value of pore volume, pore diameter distribution, mode diameter, and median diameter of the abrasive compact. The results of a polishing test, a measurement result of surface accuracy, etc., and a durability test result using a polishing platen are also shown.

[0082]

[Table 1]

[0083]

[Table 2]

[0084]

[Table 3]

Example 2 A wax-based emulsion (manufactured by Chukyo Yushi, Maxelon M) and a stearic acid emulsion (manufactured by Chukyo Yushi, Cellosol 920 having the properties shown in Table 1) were added to the raw material powder of precipitated silica obtained by a wet method. ) As the raw material powder: wax-based emulsion (in terms of solid content): stearic acid emulsion (in terms of solid content): moisture = 100: 17: 0.2:
The mixture was mixed at a weight ratio of 408 to form a slurry. This slurry is spray-dried (Okawara Kakoki, Model: LT
The granulated powder was adjusted using -8), and water was sufficiently removed in a desiccator. The dried granulated powder is mixed with potato starch (manufactured by Kishida Chemical) as a dried granulated powder: potato starch =
The mixture was mixed at a volume ratio of 1.8: 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 silica molded body. This was kept at 400 ° C. for 2 hours in a firing furnace (manufactured by Koyo Lindberg, model: 51668), and then heated to 950 ° C. for 2 hours to obtain a molded body for polishing. This was evaluated in the same manner as in Example 1 and shown in Tables 2 and 3.

Example 3 A wax-based emulsion (manufactured by Chukyo Yushi Co., Ltd., manufactured by
Maxellon M) and stearic acid emulsion (manufactured by Chukyo Yushi Co., Ltd., Cerozol 920) as raw material powder: wax emulsion (solid content conversion): stearic acid emulsion (solid content conversion): (water) = 100: 17: 0.2: 4
The mixture was mixed at a weight ratio of 08 to form a slurry. This slurry is spray-dried (Okawara Kakoki, Model: LT-
Using 8), a granulated powder was prepared in the atmosphere under the conditions of an inlet temperature of 180 ° C., a liquid sending rate of 1.2 kg / hour, and a differential pressure of 80 mmaq, and water was sufficiently removed in a desiccator and dried. Potato starch (manufactured by Kishida Chemical, average particle size 65 μm) was added to the dried granulated powder in the air at room temperature so that the volume ratio of (dried granulated powder) :( potato starch) = 1.8: 1. The mixture was mixed at atmospheric pressure 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 silica molded body. This was pressurized and degreased using a pressurized degreasing furnace (manufactured by Nemus) in nitrogen at 400 ° C., 1.5 kg / cm ² , and then fired in a firing furnace (manufactured by Koyo Lindberg, model: 51668).
The molded body for polishing was obtained by firing at 75 ° C. for 2 hours. This was evaluated in the same manner as in Example 1 and shown in Tables 2 and 3.

Example 4 An acrylic binder (manufactured by Chuo Rika Kogyo Co., Ltd., Ricabond SA-200) and a stearic acid emulsion (manufactured by Chukyo Yushi Co., Ltd.) were added to the raw material powder of the precipitated silica obtained by the wet method having the characteristics shown in Table 1. , Aerosol 920) as raw material powder: acrylic binder (in terms of solid content): stearic acid emulsion (in terms of solid content): moisture = 100: 17:
A slurry was prepared by mixing at a weight ratio of 0.2: 613. This slurry was used to prepare granulated powder using a spray dryer (manufactured by Okawara Kakoki Co., Ltd., model: LT-8), 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 = 1.8: 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 silica molded body. 400 ° C, 1.5 kg / cm
^2. After degreasing under pressure using a pressure degreasing furnace (manufactured by Nemus) in nitrogen, a firing furnace (manufactured by Koyo Lindberg Co., model: 516)
68), and baked at 1000 ° C. for 2 hours to obtain a molded body for polishing. This was evaluated in the same manner as in Example 1 and shown in Tables 2 and 3.

Comparative Example 1 Raw material powder of precipitated silica having the properties shown in Table 1 and obtained by a wet method was press-molded at a pressure of 100 kg / cm ² using a hydraulic press to obtain a silica molded body. This was fired in a firing furnace (Motoyama, model: SUPER-C) for 1300
C. for 2 hours to obtain a molded body. This was evaluated in the same manner as in Example 1. Tables 2 and 3 show, as the obtained results, the measured values of the bulk density, the BET specific surface area, and the total integrated pore volume of the silica molded body, and the results of the polishing test and the durability test using the obtained molded body.

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 to a platen rotation speed of 100 rpm. Under the predetermined processing pressure and abrasive grain concentration (20% by weight) described in Table 2 of the materials, lithium tantalate was used as the material to be polished, and a potassium hydroxide aqueous solution (pH = 12) was used as the polishing liquid. The polishing liquid was dropped at a rate of 100 ml / min and polished while being circulated. Tables 2 and 3 show measurement results such as surface accuracy as the obtained results.

Comparative Example 3 Using the same raw materials as in Example 3, a granulated powder was prepared in the same manner as in Example 3, and water was sufficiently removed in a desiccator. Unlike in Example 3, the dried granulated powder was press-formed (pressure: 100 kg / cm ² ) using a hydraulic press without adding a pore-forming agent to obtain a silica molded body. This was pressurized and degreased using a pressurized degreasing furnace (manufactured by Nemus) in nitrogen at 400 ° C. and 1.5 kg / cm ² , and then 95% in a firing furnace (manufactured by Koyo Lindberg, model: 51668).
It was baked at 0 ° C. for 2 hours to obtain a molded body for polishing. This was evaluated in the same manner as in Example 1 and shown in Tables 2 and 3.

When the results of Examples 1 to 4 and Comparative Examples 1 and 2 were compared, it was found that Comparative Example 1 had poor polishing test results, as is clear from Table 2. Further, as is apparent from Table 3, the polishing rates of Examples 1 to 4 were significantly higher than those of Comparative Examples 2 and 3. Particularly, in the method using the polishing cloth shown in Comparative Example 2, abrasive grains were used. It was found that the polishing rate was lower than in the example even when the concentration was increased.

Further, from the results of Example 3 and Comparative Example 3, the abrasive compact manufactured by the manufacturing method of the present invention is shown in FIGS. 3 to 6 as compared with the abrasive compact manufactured by the conventional manufacturing method. As shown, in the differential pore diameter distribution curve and the integral pore diameter distribution curve, the pore diameter was 1 μm (in the figure, 10,000 pores).
Angstroms), the presence of a large amount of pores is clearly observed. As described above, it was confirmed that the polishing performance, particularly the polishing rate, was significantly increased by using the polishing molded body obtained by the production method of the present invention and having a characteristic pore structure for polishing.

<Evaluation of Polishing Waste Liquid> Example 5 The polishing compact 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 4 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.

[0094]

[Table 4]

Examples 6 to 8 As shown in Table 4, the molded bodies for polishing obtained in each example were polished by the same method as in Example 5, and the polishing waste liquid was evaluated. Was.

Comparative Example 4 As shown in Table 4, the polishing compact obtained in each Comparative Example was polished by the same method as in Example 5, and the polishing waste liquid was evaluated.

From the results of Examples 5 to 8 and Comparative Example 4, it can be seen that in Examples 5 to 8, the transmittance of the polishing waste liquid is higher than that of Comparative Example 4, and the amount of free abrasive grains in the polishing waste liquid is extremely small. This shows that the burden on the waste liquid treatment in the polishing process is extremely small.

[Brief description of the drawings]

FIG. 1 is a diagram showing a differential pore diameter distribution curve, in which the vertical axis represents differential pore volume and the horizontal axis represents pore diameter.

FIG. 2 is a graph showing an integrated pore size distribution curve, in which the vertical axis represents the integrated total pore volume and the horizontal axis represents the pore size.

FIG. 3 is a view showing a differential pore diameter distribution curve of the molded article for polishing obtained in Example 3, wherein the vertical axis represents the differential pore volume (unit: cm ³ / g · (angstrom)), and the horizontal axis represents the differential pore volume. The axis represents the pore diameter (in Angstroms, logarithmic notation).

FIG. 4 is a diagram showing a differential pore diameter distribution curve of the molded article for polishing obtained in Comparative Example 3, where the vertical axis represents the differential pore volume (unit: cm ³ / g · (angstrom)) and the horizontal axis represents the differential pore volume. The axis represents the pore diameter (in Angstroms, logarithmic notation).

FIG. 5 is a graph showing an integrated pore size distribution curve of the molded article for polishing obtained in Example 3, wherein the vertical axis represents the integrated total pore volume (unit: cm ³ / g · (angstrom)); The horizontal axis represents the pore diameter (unit is Angstroms, logarithmic notation).

FIG. 6 is a graph showing an integrated pore size distribution curve of the molded article for polishing obtained in Comparative Example 3, wherein the vertical axis represents the integrated total pore volume (unit: cm ³ / g · (angstrom)); The horizontal axis represents the pore diameter (unit is Angstroms, logarithmic notation).

[Explanation of symbols]

 1: Differential pore size distribution curve shown in FIG. 1 2: Integrated pore size distribution curve shown in FIG. 2 A: Point showing pore mode size shown in FIG. 1 B: Pore median size shown in FIG. Point to show

According to the present invention, a polishing waste liquid containing a large amount of free abrasive grains, which is observed in the conventional method, is not generated during the polishing process, and the silicon wafer and the oxidizing agent can be oxidized with the same finish as the conventional method. Polishing of substrate materials such as object substrates, more durable, and faster polishing speed enables efficient polishing work, and polishing of substrate materials such as silicon wafers and oxide substrates Useful for the process.

Claims (10)

[Claims] (1) It is mainly composed of silica (silicon dioxide),
The bulk density is 0.2 to 1.5 g / cm ³ , the BET specific surface area is 10 to 400 m ² / g, the average particle size is 0.001 to 0.5 μm, and the pore mode size is 0. 0
1 to 0.3 μm, and the median pore diameter is 0.01 μm
０．３0.3 μm and the integrated total pore volume is 0.3-4 cm
^A molded article for polishing, characterized in that the accumulated pore volume of pores having a pore size of ³ / g and a pore diameter of 1 μm or more is 20 to 70% of the accumulated total pore volume of the molded article. 2. A polishing surface plate comprising the polishing molded body according to claim 1 and an accessory part. 3. A method for producing a molded article for polishing by adding a binder and a pore-forming agent to silica powder mainly composed of silica (silicon dioxide), forming the mixture, and processing the mixture to form a granulated product by mixing the silica powder and the binder. To make a granulated powder,
The method for producing a molded article for polishing according to claim 1, wherein the granulated powder is added with a pore-forming agent, mixed and molded, and then processed. 4. The method for producing a molded article for polishing according to claim 3, wherein the particle size of the granulated powder before mixing with the pore-forming agent is 5 to 300 μm in a proportion of 50% or more of the total weight of the granulated powder. , After mixing the pore-forming agent, at least 40% of the total weight of the granulated powder is 5-30.
A method for producing a molded article for polishing, characterized in that mixing is performed so as to be 0 μm. 5. The method for producing a molded article for polishing according to claim 3, wherein the pore-forming agent to be added and mixed has an average particle diameter of 0.1 to 200 μm. How to make the body. 6. The method of manufacturing a molded article for polishing according to claim 3, wherein the amount of the pore-forming agent to be added and mixed is (weight of the pore-forming agent) / (weight of the granulated powder). ) = 2/1 ~
A method for producing a molded article for polishing, characterized by being 1/10 (weight ratio). 7. The method for producing a molded article for polishing according to claim 3, wherein a pore-forming agent is added and molded.
A method for producing a molded body for polishing, characterized by processing at a temperature of 00 ° C. or lower. 8. A polishing method comprising polishing a material to be polished using the polishing platen according to claim 2. 9. The polishing method according to claim 8, wherein the material to be polished is a substrate material. 10. The polishing method according to claim 8 or 9, wherein the polishing is performed without using free abrasive grains, and the polishing waste liquid is removed.
A polishing method, wherein the transmittance at 0 nm is 10% or more of water.