JP2001158680A - Silicon carbide-metal complex, method for producing the same, member for wafer-polishing device and table for wafer-polishing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silicon carbide-metal complex extremely superior in soaking properties, thermal responsibility and dimensional stability. SOLUTION: This table 2 is used for wafer-polishing device 1, and comprises base materials 11A and 11B made from a porous silicon carbide sintered body. The porous silicon carbide sintered body has open pores 23 present in a structure constituted of silicon carbide crystals 21 and 22. The average particle diameter of the silicon carbide crystals 21 and 22 is >=20 μm, and the porosity and the thermal conductivity thereof are <=30% and >=160 W/m.K respectively. The metal of 15-50 pts.wt. based on the silicon carbide of 100 pts.wt. is impregnated therein.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicon carbide / metal composite and a method for manufacturing the same, as well as a member for a wafer polishing apparatus and a table for a wafer polishing apparatus.

[0002]

2. Description of the Related Art Conventionally, silicon carbide (SiC) has been known as a kind of non-oxide ceramic. Silicon carbide sintered body has thermal conductivity, heat resistance, thermal shock resistance, wear resistance, hardness,
It has suitable characteristics such as excellent oxidation resistance and corrosion resistance.

[0003] Therefore, the silicon carbide sintered body is exposed to abrasion-resistant materials such as mechanical seals and bearings, refractory materials for high-temperature furnaces, heat-resistant structural materials such as heat exchangers and combustion tubes, and acids and alkalis. It can be said that it is a widely usable material such as a corrosion-resistant material such as a pump part which is easily damaged. In recent years, there has been a movement to use a porous silicon carbide sintered body as a constituent material of a semiconductor manufacturing apparatus (for example, a wafer polishing apparatus or the like) by paying attention to the above-mentioned various properties, particularly high thermal conductivity. In addition to this, it has been proposed to produce a silicon carbide / metal composite having better thermal conductivity than a non-impregnated body by impregnating a metal into the open pores present in the porous carbon sintered body. I have.

[0004] A wafer polishing apparatus refers to a lapping machine or a polishing machine for polishing a device formation surface of a semiconductor wafer. This apparatus includes a wafer top plate, a table made of a silicon carbide / metal composite, and the like. Cooling water is circulated through a flow path provided in the table. A semiconductor wafer is attached to the holding surface of the wafer top plate using a thermoplastic wax. The semiconductor wafer held by the rotating pusher plate is pressed from above onto the polished surface of the table. As a result, the semiconductor wafer comes into sliding contact with the polishing surface, and one side surface of the wafer is uniformly polished. Then, the heat generated in the wafer at this time is conducted outside the apparatus by the cooling water circulating in the flow path after conducting in the table.

[0005]

SUMMARY OF THE INVENTION By the way, silicon carbide
Since the metal composite has a property of efficiently conducting heat, there is an advantage that temperature variation hardly occurs inside. Therefore, such a composite is provided with high thermal uniformity and thermal responsiveness. Further, as a result of avoiding the generation of thermal stress and making the base material less likely to warp, the shape stability is improved. By the way, although the silicon carbide / metal composite has a higher thermal conductivity than the silicon carbide non-impregnated body, the value of the thermal conductivity at present is about 100 W / m · K to 150 W / m · K. . Therefore, it has been considered that a further improvement in thermal conductivity is indispensable in order to realize a material having more excellent thermal uniformity, thermal responsiveness, and shape stability. Similarly, when this composite is used for the table, it has been considered that improvement in thermal conductivity is essential for realizing a large-diameter and high-quality wafer.

The present invention has been made in view of the above problems, and a first object of the present invention is to provide a silicon carbide / metal composite having extremely excellent heat uniformity, thermal responsiveness, and shape stability. is there. A second object is to provide a method that can reliably produce such a suitable composite. further,
A third object is to provide a table for a wafer polishing apparatus suitable for manufacturing a large-diameter, high-quality wafer.

[0007]

In order to solve the above-mentioned problems, according to the first aspect of the present invention, open pores exist in a porous structure composed of silicon carbide crystals, and the open pores exist in the open pores. In the silicon carbide / metal composite impregnated with a metal, the silicon carbide crystal has an average particle diameter of 20 μm or more, a porosity of 30% or less, and a thermal conductivity of 160 W / m · K.
The gist is a silicon carbide / metal composite impregnated with 15 to 50 parts by weight of metal per 100 parts by weight of silicon carbide.

According to the second aspect of the present invention, open pores exist in the porous structure constituted by silicon carbide crystals,
In the silicon carbide / metal composite in which the open pores are impregnated with a metal, the silicon carbide crystals have an average particle size of 20 μm.
m-100 μm, porosity 5% -30%, thermal conductivity 1
The gist of the present invention is a silicon carbide / metal composite which is 60 W / m · K or more and is impregnated with 15 to 50 parts by weight of metal per 100 parts by weight of silicon carbide.

According to a third aspect of the present invention, in the first or second aspect, 15 to 45 parts by weight of metal silicon is impregnated with respect to 100 parts by weight of silicon carbide. According to a fourth aspect of the present invention, in the first or second aspect, 20 parts by weight to 50 parts by weight with respect to 100 parts by weight of silicon carbide.
It was assumed that metal aluminum was impregnated in parts by weight.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the average particle size is 0.1 μm to 0.1 μm.
It contains 10% by volume to 50% by volume of fine silicon carbide crystals of 1.0 μm and 50% by volume to 90% by volume of coarse silicon carbide crystals having an average particle size of 25 μm to 65 μm.

[0011] In the invention according to claim 6, open pores are present in the porous structure composed of silicon carbide crystals,
The open pores are impregnated with 15 to 50 parts by weight of metal per 100 parts by weight of silicon carbide, the silicon carbide crystal has an average particle size of 20 μm or more, a porosity of 30% or less, and a thermal conductivity of 160 W / M · K or more, a method for producing a silicon carbide / metal composite having an average particle size of 5 μm to 100 μm
With respect to 100 parts by weight of the coarse powder of α-type silicon carbide of m, 10 parts by weight to 100 parts by weight of fine powder of α-type silicon carbide having an average particle size of 0.1 μm to 1.0 μm are blended, and this is uniformly mixed. A step of mixing, a step of molding the mixture obtained in the above step into a predetermined shape to obtain a molded body,
A method for producing a silicon carbide / metal composite, comprising: firing at a temperature of 2400 ° C. to obtain a sintered body; and impregnating the formed body or the sintered body with a metal. And

According to a seventh aspect of the present invention, in the sixth aspect, the molded body contains 1% to 10% by weight of an organic substance as a carbon source in terms of carbon weight. According to an eighth aspect of the present invention, there is provided a member used for a wafer polishing apparatus, wherein the member for a wafer polishing apparatus comprising the silicon carbide / metal composite according to any one of the first to fifth aspects is provided. Make a summary.

According to a ninth aspect of the present invention, there is provided a table having a polishing surface on which a semiconductor wafer held on a holding surface of a wafer holding plate constituting a wafer polishing apparatus is slidably contacted. The substrates are joined to each other in a state where a plurality of substrates made of the silicon carbide / metal composite according to any one of the above are laminated, and a fluid flow path is provided at a joint interface of the substrates. The gist is a table for a wafer polishing apparatus.

The "action" of the present invention will be described below. According to the first to fifth aspects of the present invention, the average particle size of the silicon carbide crystal constituting the porous structure is set to a relatively large value of 20 μm or more. Since the efficiency of heat conduction inside the crystals is generally higher than the efficiency of heat conduction between crystals, the larger the average particle size, the higher the thermal conductivity. Further, the fact that the porosity of the porous structure is set to a small value of 30% or less also contributes to an improvement in thermal conductivity. That is, when the porosity is reduced, the voids in the porous structure are reduced, so that heat is easily conducted. Further, the fact that the metal is impregnated with 15 parts by weight to 50 parts by weight with respect to 100 parts by weight of silicon carbide also contributes to the improvement of the thermal conductivity.

For this reason, the thermal conductivity as a whole is 160
As compared with a conventional composite having a value considerably lower than W / m · K, temperature variation hardly occurs inside. As a result, the composite is provided with extremely high heat uniformity and thermal responsiveness. In addition, as a result that the generation of thermal stress is reliably avoided and the substrate is less likely to warp, extremely high shape stability is imparted to the composite.

In this case, the average particle size of the silicon carbide crystal is 20
If it is less than μm or the porosity exceeds 30%, the thermal conductivity is 160 W / m ·
It becomes difficult to set a high value of K or more. Therefore, it becomes impossible to sufficiently improve the heat uniformity, the thermal responsiveness, and the shape stability. The value of the thermal conductivity was 160 W / m.
-It is necessary to be K or more, and 180W /
m · K to 280 W / m · K,
It is particularly preferable that it is 0 W / m · K to 260 W / m · K.

The average particle size of the silicon carbide crystal is 20 μm to 1 μm.
00 μm, preferably 30 μm to 90 μm.
μm, more preferably 40 μm to 70 μm
Most preferably, it is set to m. If the average particle size is too large, the composite may be excessively densified.

The porosity of the open pores is preferably set to 5% to 30%, more preferably 10% to 25%, and most preferably 10% to 20%.

The composite has an average particle size of 0.1 μm or more.
50% by volume of coarse silicon carbide crystal (hereinafter, referred to as coarse crystal) containing 10% by volume to 50% by volume of fine silicon carbide crystal (hereinafter, referred to as fine crystal) of 1.0 μm and having an average particle size of 25 μm to 150 μm. Preferably, it contains about 90% by volume.

As described above, in the case of a composite in which fine crystals and coarse crystals are contained at an appropriate ratio, the gaps formed between the coarse crystals are likely to be filled with the fine crystals. Becomes smaller. As a result, the thermal resistance of the composite is further reduced, which is considered to have greatly contributed to the improvement in thermal conductivity.

The average diameter of the fine crystals is 0.1 μm to 1.0 μm.
μm, typically between 0.2 μm and 0.9 μm
Is more preferably set to 0.3 μm to 0.7 μm.
Most preferably, it is set to μm. If an attempt is made to make the average particle size of the fine crystals extremely small, it is necessary to use expensive fine powder, which may lead to a rise in material costs. Conversely, if the average grain size of the fine crystals is too large, the voids formed between the coarse crystals cannot be sufficiently filled, and the thermal resistance of the composite may not be sufficiently reduced.

[0022] In the composite, the fine crystals are 10% by volume to 5% by volume.
0% by volume, 15% to 40% by volume
It is more preferably contained, and 20% to 40% by volume
Most preferably, it is included. If the content ratio of the fine crystals is too small, it becomes difficult to secure a sufficient amount of the fine crystals to fill the voids formed between the coarse crystals, and the thermal resistance of the composite may not be reliably reduced. Conversely, if the content ratio of the fine crystals is too large, the fine crystals filling the voids become rather surplus, and it is not possible to secure a coarse crystal which is originally necessary for improving the thermal conductivity. Therefore, the thermal resistance of the composite may be rather increased.

Further, the average grain size of the coarse crystals in the composite is preferably set to 25 μm to 150 μm.
It is more preferably set to 0 μm to 100 μm,
Most preferably, it is set to 60 μm to 80 μm.
If an attempt is made to reduce the average particle size of the coarse crystals to a very small value, the particle size difference from the fine particles becomes small, so that the effect of reducing the thermal resistance by mixing the fine crystals and the coarse crystals may not be expected. Conversely, if the average grain size of the coarse crystals is too large, individual voids formed between the coarse crystals will increase, so that even if there is a sufficient amount of fine crystals, the voids should be sufficiently filled. Becomes difficult. Therefore, there is a possibility that the thermal resistance of the composite cannot be sufficiently reduced.

In the composite, the crude crystals are from 50% by volume to 9% by volume.
0% by volume, 60% to 85% by volume
More preferably, 60% to 80% by volume
Most preferably, it is included. If the content ratio of the coarse crystals is too small, coarse crystals that are originally necessary for improving the thermal conductivity cannot be secured, and the thermal resistance of the composite may be rather increased. Conversely, if the content ratio of the coarse crystals is too large, the content ratio of the fine crystals becomes relatively small, and it becomes impossible to sufficiently fill the voids formed between the coarse crystals. Therefore, there is a possibility that the thermal resistance of the composite cannot be reliably reduced.

In the present invention, the metal must be impregnated with 15 to 50 parts by weight based on 100 parts by weight of silicon carbide. This is because, when the metal is impregnated, the metal is buried in the open pores of the sintered body to become an apparently dense body, and as a result, the thermal conductivity and the strength are improved.

As the impregnating metal, it is particularly preferable to select metallic silicon. Metallic silicon has a high thermal conductivity in itself, in addition to being a material that is familiar with silicon carbide. Therefore, by filling the open pores of the sintered body with metallic silicon, it is possible to surely achieve improvements in thermal conductivity and strength.

In this case, the metal silicon is silicon carbide 10
It is preferably impregnated with 15 to 45 parts by weight, more preferably 15 to 30 parts by weight, based on 0 part by weight. If the impregnation amount is less than 15 parts by weight, the open pores cannot be sufficiently filled, and the thermal resistance of the composite may not be reduced reliably.
Conversely, when the impregnated amount exceeds 30 parts by weight, the ratio of the crystal part is relatively reduced, and in some cases, the thermal conductivity may be rather reduced.

When a material other than metal silicon, for example, metal aluminum is selected, the material is selected from silicon carbide 1
It is preferable that 20 parts by weight to 50 parts by weight is impregnated with respect to 00 parts by weight. If the impregnation amount is outside the above range, the thermal conductivity may be reduced.

According to the sixth aspect of the present invention, the porous silicon carbide sintered body of the present invention comprises, as described above, a material preparing step, a forming step, in which a coarse powder and a fine powder are blended in a predetermined ratio and mixed. It is manufactured through a firing step and a metal impregnation step. The metal impregnation step may be performed after the firing step, or may be performed before the firing step.

In the material preparation step, the average particle size is 5
10 parts by weight to 100 parts by weight of fine powder of α-type silicon carbide having an average particle size of 0.1 μm to 1.0 μm are blended with 100 parts by weight of coarse powder of α-type silicon carbide of μm to 100 μm. Perform uniform mixing.

The average particle size of the coarse powder of α-type silicon carbide is 5 μm.
m to 100 μm, and 15 μm to 7 μm.
It is more preferably set to 5 μm, and 25 μm to 6 μm.
Most preferably, it is set to 0 μm. When the average particle size of the α-type silicon carbide coarse powder is less than 5 μm, the effect of suppressing abnormal grain growth may be reduced. Conversely, if the average particle size of the α-type silicon carbide coarse powder exceeds 60 μm, the moldability may be deteriorated and the strength of the obtained composite may be reduced.

The average particle size of the fine powder of α-type silicon carbide is 0.1.
It is often set to 1 μm to 1.0 μm, and 0.1 μm
m to 0.8 μm, more preferably 0.
Most preferably, it is set to 2 μm to 0.5 μm.
If the average particle size of the fine powder of α-type silicon carbide is less than 0.1 μm, it becomes difficult to control the grain growth, and inevitably increases the material cost. Conversely, if the average particle size of the α-type silicon carbide fine powder exceeds 1.0 μm, the voids formed between the coarse crystals may be difficult to fill. In addition,
The reason for choosing the α-type as the fine powder is that the thermal conductivity tends to be somewhat higher than that of the β-type.

The amount of the fine powder is 10 parts by weight to 10 parts by weight.
The amount is preferably 0 parts by weight, more preferably 15 parts by weight to 65 parts by weight, and most preferably 20 parts by weight to 60 parts by weight. If the amount of the fine powder is too small, it is difficult to secure a sufficient amount of fine crystals to fill the voids formed between the coarse crystals, and the thermal resistance of the composite may not be sufficiently reduced. Further, in order to obtain a desired pore diameter of 20 μm or more, it is necessary to set the firing temperature to an extremely high temperature, which is disadvantageous in cost. Conversely, if the compounding amount of the fine powder is too large, coarse crystals required to improve the thermal conductivity cannot be secured, and the thermal resistance of the composite may increase. Also, it becomes difficult to obtain a composite having excellent strength.

In the above-mentioned material preparation step, a molding binder and a dispersion solvent are blended together with the two kinds of powders as required. Then, this is uniformly mixed and kneaded to appropriately adjust the viscosity, so that a raw material slurry is first obtained. As means for mixing the raw material slurry,
Vibration mill, attritor, ball mill, colloid mill,
There are high-speed mixers and the like. As a means for kneading the mixed raw material slurry, for example, there is a kneader or the like.

Examples of the molding binder include polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, polyethylene glycol, phenol resin, epoxy resin, and acrylic resin. It is preferable that the compounding ratio of the molding binder is generally in the range of 1 part by weight to 10 parts by weight based on 100 parts by weight of the total of the silicon carbide powder. If this ratio is less than 1 part by weight, the strength of the obtained molded article becomes insufficient, and the handleability deteriorates. Conversely, if the ratio exceeds 10 parts by weight, cracks are likely to occur in the molded body when the molding binder is removed by drying or the like, and the yield is deteriorated.

Organic solvents such as benzene and cyclohexane, alcohols such as methanol, and water can be used as the dispersion solvent. The raw material slurry further contains an organic substance serving as a carbon source in an amount of 1% by weight to 1% by weight in terms of carbon weight.
0% by weight, especially 6% by weight to 9% by weight is preferably blended. That is, the carbon derived from the organic substance adheres to the surface of the silicon carbide of the sintered body, so that the impregnated metallic silicon and the carbon react with each other to generate silicon carbide there again. Therefore, strong necking occurs there, thereby improving thermal conductivity and strength.

Here, if the amount of the organic substance in the molded body is too small, the silicon oxide film covering the surface of the sintered body becomes thick, and it becomes difficult for metallic silicon to enter the sintered body side. It may be difficult to generate.

Conversely, if the amount of the organic substance in the molded article is too large, for example, when a resin is selected, the releasability at the time of molding may be deteriorated. Further, as a result of inhibiting sintering of silicon carbide, strength may be reduced.

Examples of the organic substance include phenolic resin, carbon black, acetylene black, pitch and tar. Among them, phenolic resin is advantageous in that raw materials can be uniformly mixed when a ball mill is used.

Next, granules of silicon carbide are formed using the raw material slurry. As a method of granulating the silicon carbide powder, a conventional general-purpose technique such as a granulation method by spray drying (so-called spray drying method) can be used. That is, a method in which the raw material slurry is sprayed into a container maintained at a high temperature state, and the material slurry is rapidly dried is applicable.

Here, the water content of the granules is from 0.1% by weight to 2.%.
It is preferably 0% by weight, more preferably 0.2% to 0.9% by weight. The reason is that when the moisture content of the granules is within the above range, the density of the molded body and the density of the sintered body are increased, and as a result, the thermal conductivity is increased. When the water content of the granules is less than 0.1% by weight, the density of the molded body and the density of the sintered body are not sufficiently increased, and the thermal conductivity is hardly increased. Conversely, if the moisture content of the granules exceeds 2.0% by weight, cracks may easily occur in the molded product during drying,
This leads to a decrease in yield.

In the subsequent molding step, granules made of the mixture obtained in the material preparation step are molded into a predetermined shape to produce a molded body. The molding pressure at that time is 1.0 t / c
m ^{2 to} 1.5 t / cm ² , and 1.1 t / c
More preferably, it is m ^{2 to} 1.4 t / cm ² . The reason is that the thermal conductivity increases as a result of the increase in the density of the molded body grooves and the density of the sintered body. Molding pressure is 1.0t / cm ²
If it is less than 3, the density of the compact and the density of the sintered compact do not become sufficiently high, and the thermal conductivity does not easily become high. Conversely, 1.5
When molding is performed at a pressure greater than t / cm ² , the density of the molded body can be sufficiently increased, but a dedicated press device is required, which results in a rise in equipment costs and difficulty in manufacturing. Become.

The density of the molded product is 2.0 g / cm ³
It is often set as above, especially 2.2 g / cm ³
It is preferably set to ~2.7g / cm ^3. The reason is that if the density of the compact is too low, the number of bonding portions between silicon carbide particles decreases. Therefore, the strength of the obtained porous body becomes low, and the handleability becomes poor. Conversely, if the density of the molded body is to be increased, a dedicated press device is required as described above, which results in an increase in equipment cost and difficulty in manufacturing.

In the subsequent firing step, the compact obtained by the compacting step is heated at a temperature in the range of 1700 ° C. to 2400 ° C., preferably in the temperature range of 2000 ° C. to 2400 ° C.
It is particularly preferably fired in a temperature range of 2000 to 2300 ° C. to produce a sintered body.

If the firing temperature is too low, it is difficult to sufficiently develop a neck portion for bonding silicon carbide particles, and it may not be possible to achieve high thermal conductivity and high strength. Conversely, if the firing temperature is too high, the thermal decomposition of silicon carbide will start, resulting in a decrease in the strength of the sintered body. Moreover, as a result of an increase in the amount of heat energy to be applied to the firing furnace, there is a disadvantage in cost.

During firing, the inside of the firing furnace is filled with a gas atmosphere (for example, a non-oxidizing atmosphere or an inert atmosphere) composed of at least one selected from, for example, argon, helium, neon, nitrogen, hydrogen and carbon monoxide. ) Should be kept. At this time, the inside of the firing furnace may be in a vacuum state.

Further, at the time of firing, it is advantageous to suppress the volatilization of silicon carbide from the compact in order to promote the growth of the neck portion. As a method for suppressing the volatilization of silicon carbide from the compact, it is effective to charge the compact in a heat-resistant container capable of blocking the invasion of the outside air. As a material for forming the heat-resistant container, graphite or silicon carbide is preferable.

In the subsequent metal impregnation step, the sintered body (ie, the unimpregnated composite) is impregnated with metal as follows.
For example, when impregnating metal silicon, it is preferable to impregnate the sintered body with a carbonaceous substance in advance. Such carbonaceous materials include, for example, furfural resin, phenol resin, lignin sulfonate, polyvinyl alcohol, corn starch, molasses, coal tar pitch,
Various organic substances such as alginate can be used.
Note that pyrolytic carbon such as carbon black and acetylene black can be used in the same manner.

The reason why the carbon chamber material is impregnated in advance is that a new silicon carbide film is formed on the surface of the open pores of the sintered body, and thus the bond between the molten silicon and the porous body is strong. Because it becomes. Also, the strength of the sintered body is increased by the impregnation of the carbon chamber material.

As a method of filling metallic silicon into open pores, for example, there is a method of impregnating metallic silicon by heating and melting. Further, a method in which finely divided metal silicon is dispersed in a dispersion medium, the dispersion is impregnated in a porous body, dried, and then heated to a temperature equal to or higher than the melting temperature of the metal silicon is also applicable.

However, the metal impregnation step may be performed on the molded body, in other words, before the firing step. According to this method, although the quality of the obtained product is slightly inferior, the cost can be reduced by saving power.

By carrying out each of the above steps, it is possible to obtain silicon carbide with excellent heat uniformity, thermal responsiveness and shape stability.
The metal composite can be reliably manufactured. According to the invention described in claim 8, as a result of the semiconductor wafer rotating and slidingly contacting the polishing surface, one side surface of the semiconductor wafer is uniformly polished by the polishing surface. The above table is
Since the composite body is extremely excellent in heat uniformity, thermal responsiveness and shape stability, the influence of heat or the like on the semiconductor wafer during polishing can be minimized. Therefore, according to the table of the present invention, a large-diameter and high-quality wafer can be reliably manufactured.

[0053]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a wafer polishing apparatus 1 according to an embodiment of the present invention will be described in detail with reference to FIGS.

FIG. 1 shows a wafer polishing apparatus 1 of the present embodiment.
Is schematically shown. The table 2 constituting the wafer polishing apparatus 1 has a disk shape. The upper surface of the table 2 is a polishing surface 2a for polishing the semiconductor wafer 5. A polishing cloth (not shown) is attached to the polishing surface 2a. The table 2 according to the present embodiment is directly and horizontally fixed to the upper end surface of the cylindrical rotating shaft 4 without using a cooling jacket. Therefore, when the rotation shaft 4 is driven to rotate, the table 2 rotates integrally with the rotation shaft 4.

As shown in FIG. 1, the wafer polishing apparatus 1 includes a plurality (two in FIG. 1 for convenience of illustration) of wafer holding plates 6. As a material for forming the plate 6, for example, a glass, a ceramic material such as alumina, a metal material such as stainless steel, or the like is employed. A pusher bar 7 is fixed to the center of one side surface (non-holding surface 6b) of each wafer holding plate 6. Each pusher bar 7 is located above the table 2 and is connected to driving means (not shown). Each pusher bar 7 horizontally supports each wafer holding plate 6. At this time, the holding surface 6
a is in a state facing the polishing surface 2a of the table 2. Further, each pusher bar 7 can not only rotate with the wafer holding plate 6 but also move up and down within a predetermined range. Instead of the method of moving the plate 6 up and down, a structure of moving the table 2 up and down may be adopted. The semiconductor wafer 5 is adhered to the holding surface 6a of the wafer holding plate 6 using, for example, thermoplastic wax. The semiconductor wafer 5 may be attracted to the holding surface 6a by evacuation or electrostatically. At this time, the polished surface 5a of the semiconductor wafer 5 needs to face the polished surface 2a of the table 2.

Next, the configuration of the table 2 will be described in detail. As shown in FIG. 1 and FIG. 2, the table 2 of the present embodiment includes two bases 11 made of a silicon carbide / metal composite.
A, 11B is a laminated ceramic structure. On the back surface of the upper base material 11A, a cooling water channel 1
Grooves 13 forming a part of 2 are formed in a predetermined pattern. The two substrates 11A and 11B are integrated by being joined to each other via the silver brazing material layer 14. As a result, the water channel 12 is formed at the joint interface between the substrates 11A and 11B. A through hole 15 is formed substantially at the center of the lower substrate 11B. These through holes 15
Is provided with a flow path 4 a provided in the rotating shaft 4 and the water passage 12.
And the communication.

The groove 13 forming a part of the water channel 12 is a ground groove formed by grinding the back surface of the upper base material 11A after raw processing and before firing. The depth of the groove 13 is 3
It is preferable that the width is set to about 10 mm and the width is set to about 20 mm.

Hereinafter, some examples which embody the present embodiment will be introduced. [Example 1] In the production of Example 1, as a starting material, a coarse powder of α-type silicon carbide having an average particle diameter of 30 µm (# 40
0) and α-type silicon carbide fine powder (GMF-15H2) having an average particle diameter of 0.3 μm. Then, 30 parts by weight of the fine powder was blended with 100 parts by weight of the coarse powder, and this was uniformly mixed.

5 parts by weight of polyvinyl alcohol, 3 parts by weight of phenol resin and 50 parts by weight of water were mixed with 100 parts by weight of this mixture, and then mixed in a ball mill for 5 hours to obtain a uniform mixture. After drying the mixture for a predetermined time to remove a certain amount of water, an appropriate amount of the dried mixture was collected and granulated. At this time, the water content of the granules was adjusted to be about 0.8% by weight. Then
The granules of the mixture were crushed at 1.3 t /
It was molded at a press pressure of cm ² . The density of the obtained disk-shaped formed body (50 mmφ, 5 mmt) is 2.6 g / cm.
^{Was 3} .

Subsequently, by grinding the bottom surface of the molded body to become the upper base material 11A later, a groove 13 having a depth of 5 mm and a width of 10 mm was formed on almost the entire bottom surface. Next, the green compact was charged into a graphite crucible and fired using a Tamman-type firing furnace. The firing was performed in an argon gas atmosphere at 1 atm. During firing, the maximum temperature is 22 ° C. at a rate of 10 ° C./min.
It was heated to 00 ° C. and then kept at that temperature for 4 hours.

Next, the obtained porous sintered body was previously impregnated with a phenol resin (carbonization ratio: 30% by weight) under vacuum,
And dried. Thereafter, the surface of the porous sintered body was coated with a slurry containing metallic silicon. Here, the slurry has an average particle size of 20 μm and a purity of 9 μm.
A mixture of 100 parts by weight of 9.9999% by weight or more of metal silicon powder and 60 parts by weight of a 5% acrylate / benzene solution was used. Then, the porous sintered body coated with metallic silicon is heated in an argon gas stream at a rate of 450 ° C./hour, and the maximum temperature is 145.
It was kept at 0 ° C. for about 1 hour. By such a treatment, metallic silicon was permeated into the porous sintered body to obtain a silicon carbide / metal composite. Here, the impregnation amount of metal silicon with respect to 100 parts by weight of silicon carbide was set to 30 parts by weight.

The obtained substrate 1 made of silicon carbide / metal composite
In 1A and 11B, the porosity of the open pores in the porous structure is 20%, and the thermal conductivity as a whole is 210 W / m ·
K, the overall density was 3.0 g / cm ³ . The average particle size of the silicon carbide crystals was 30 μm. Specifically, it contained 20% by volume of fine crystals having an average particle size of 1.0 μm and 80% by volume of coarse crystals having an average particle size of 40 μm. For reference, FIG. 4C shows a graph of the particle size distribution in Example 1.

Subsequently, after performing a facing process by a conventionally known method, two substrates 11A, 11A are formed using a silver brazing material.
B was joined and integrated. Further, by polishing the surface of the upper substrate 11A, the table 2 having a polished surface 2a having a surface roughness suitable for polishing the semiconductor wafer 5 was finally completed.

The table 2 of Example 1 thus obtained is set in the above-mentioned various polishing apparatuses 1, and the semiconductor wafers 5 of various sizes are polished while constantly circulating the cooling water W in the water channel 12. Was. When the semiconductor wafer 5 obtained through polishing by various polishing apparatuses 1 was observed, the wafer 5 was not damaged irrespective of the wafer size. Also, there was no occurrence of a large warp in the wafer 5. That is, table 2 of the present embodiment
In the case of using, a very large diameter and high quality semiconductor wafer 5
Was obtained.

FIG. 3 is an enlarged conceptual sectional view of the table 2 of the first embodiment. The silicon carbide / metal composite constituting table 2 includes fine crystal 21 and coarse crystal 2.
And 2. The voids formed between the coarse crystals 22 are:
It is almost filled with the fine crystal 21. Therefore,
It can be understood that the substantial void ratio, that is, the porosity of the open pores 23 is considerably small. In addition, the remaining voids are in a state in which the metal silicon 24 is buried. [Example 2] In the production of Example 2, the average particle diameter was 35%.
A .mu.m coarse powder of .alpha.-type silicon carbide (# 360) was used, and 40 parts by weight of the fine powder were blended with 100 parts by weight of the coarse powder, and were uniformly mixed. Other conditions were basically the same as in Example 1.

As a result, the porosity of the open pores of the porous structure of the obtained silicon carbide / metal composite substrates 11A and 11B was 17%, the overall thermal conductivity was 220 W / m · K, and the density was It was 3.0 g / cm ³ . The average particle size of the silicon carbide crystals was 36 μm. Specifically, the average particle size is 1
20% by volume of fine crystals of 0 μm and 80% by volume of coarse crystals having an average particle size of 45 μm. FIG. 4B shows a graph of the particle size distribution in Example 2 for reference.

After completing the table 2 in the same procedure as in the first embodiment, the table 2 was set in the various polishing apparatuses 1 described above, and the semiconductor wafers 5 of various sizes were polished. Excellent results were obtained. Example 3 In the preparation of Example 3, the average particle diameter was 57%.
A coarse powder of α-type silicon carbide (# 240) having a thickness of μm was used, and 40 parts by weight of the fine powder was blended with 100 parts by weight of the coarse powder, and the mixture was uniformly mixed. Other conditions were basically the same as in Example 1.

As a result, the porosity of the open pores of the obtained silicon carbide / metal composite substrates 11A and 11B was 15%,
Thermal conductivity is 230 W / m · K and density is 3.1 g / cm ³
Met. The average particle size of the silicon carbide crystals was 65 μm. Specifically, it contained 20% by volume of fine crystals having an average particle size of 1.0 μm and 80% by volume of coarse crystals having an average particle size of 80 μm. FIG. 4A shows a graph of the particle size distribution in Example 3 for reference.

After the table 2 was completed in the same procedure as in the first embodiment, it was set in the above-mentioned various polishing apparatuses 1 and the semiconductor wafers 5 of various sizes were polished. Excellent results were obtained. [Comparative Example] In the production of the comparative example, the average particle diameter was 10 μm.
Was used, and 45 parts by weight of a fine powder of α-type silicon carbide having an average particle diameter of 0.7 μm was blended with 100 parts by weight of the coarse powder and uniformly mixed. . Other conditions were basically the same as in Example 1.

After mixing 5 parts by weight of polyvinyl alcohol and 50 parts by weight of water with respect to 100 parts by weight of this mixture, the mixture was mixed in a ball mill for 5 hours to obtain a uniform mixture. After drying the mixture for a predetermined time to remove a certain amount of water, an appropriate amount of the dried mixture was collected and granulated. Next, the granules of the mixture were molded at a pressing pressure of 0.6 t / cm ² using a metal stamping die. The density of the obtained disc-shaped green compact was 2.0 g / cm ³ . Thereafter, metal silicon impregnation was performed under the same conditions as in Example 1.

Subsequently, a groove 13 having a depth of 5 mm and a width of 10 mm was formed on almost the entire bottom surface by grinding the bottom surface of the molded body to be the upper base material 11A later. Next, the green compact was charged into a graphite crucible and fired using a Tamman-type firing furnace. The firing was performed in an argon gas atmosphere at 1 atm. During firing, the maximum temperature is 17 ° C. at a rate of 10 ° C./min.
It was heated to 00 ° C. and then kept at that temperature for 4 hours.

As a result, the porosity of the open pores of the porous structure of the obtained substrates 11A and 11B made of silicon carbide / metal composite was 38%, the thermal conductivity was 130 W / m · K, and the density was 2.
It was 8 g / cm ³ . The average particle size of the silicon carbide crystals was 10 μm.

Therefore, according to the above-described embodiments of the present embodiment, the following effects can be obtained. (1) In each of the composites constituting Table 2 of each embodiment, the average particle diameter of silicon carbide crystal is 20 μm to 100 μm.
m, the porosity of the porous structure is 5% to 30%, and the thermal conductivity as a whole is 160 W / m · K or more. Also,
15 to 45 parts by weight of metallic silicon is impregnated with respect to 100 parts by weight of silicon carbide.

Further, in each of these composites, fine crystals having an average particle size of 0.1 μm to 1.0 μm are formed in an amount of 10% by volume or less.
Contains 50% by volume and has an average particle size of 25 μm to 150 μm
m of coarse crystals of 50% by volume to 90% by volume.

Therefore, the thermal conductivity value is 160 W
/ M · K, which gives the table 2 an extremely high thermal conductivity. For this reason, temperature variation is less likely to occur inside the composite than in conventional products. As a result, the composite is provided with extremely high heat uniformity and thermal responsiveness. Further, the generation of thermal stress is reliably avoided, and the base materials 11A, 11
As a result, the composite is provided with extremely high shape stability. As a result, the diameter and quality of the wafer 5 can be reliably increased.

(2) In the case of this table 2, the base material 11
The cooling water W can flow through the water channel 12 existing at the joint interface between the A and the 11B. Therefore, the heat generated during polishing of the semiconductor wafer 5 can be directly and efficiently released from the table 2 and the temperature can be finely controlled. Therefore, as compared with the conventional apparatus in which the table 2 is placed on the cooling jacket to perform indirect cooling, the temperature variation in the table 2 is extremely small, and the heat uniformity and the thermal response are remarkably improved. Therefore, according to this apparatus 1, the wafer 5 is less likely to be adversely affected by heat, and it is possible to cope with an increase in the diameter of the wafer 5. Moreover, the wafer 5
Can be polished with high accuracy, so that it is possible to cope with high quality.

The embodiment of the present invention may be modified as follows. The base materials 11A and 11B may be joined using a metal-based joining material represented by a brazing material, or may be joined using an adhesive made of a resin (for example, an epoxy resin).

The base materials 11A and 11B do not necessarily have to be joined via the brazing material layer 14. For example, instead of omitting the brazing material layer 14, the base materials 11A and 11B
B may be integrated by fastening a bolt and a nut.

The impregnating metal impregnated in the sintered body is not limited to the metallic silicon described in the embodiment. For example, the impregnation may be performed using various conductive metal materials such as aluminum, gold, silver, copper, and titanium.

Table 2 of the embodiment having a two-layer structure
Alternatively, the present invention may be embodied in a table having a three-layer structure. Of course, a stacked structure of four or more layers may be used. The groove 13 may be formed only on the upper substrate 11A, or may be formed only on the lower substrate 11B,
Alternatively, it may be formed on both base materials 11A and 11B.

In using the table 2 of the present embodiment, a liquid other than water may be circulated in the water channel 12.
Further, a gas may be circulated. The silicon carbide / metal composite of the present invention may be used for the table 2 in a wafer polishing apparatus, or may be used for a member other than the table (such as a wafer top plate). Of course, the present invention is not limited to being used as a constituent material of a semiconductor manufacturing apparatus typified by the wafer polishing apparatus table 2 and the like. For example, the composite may be used as a radiator of an electronic component mounting substrate. The composite can also be used for wear-resistant materials such as mechanical seals and bearings, refractory materials for high-temperature furnaces, heat-resistant structural materials such as heat exchangers and combustion tubes, and corrosion-resistant materials such as pump parts. Of course it is possible.

Next, in addition to the technical ideas described in the claims, the technical ideas grasped by the above-described embodiments will be listed below together with their effects. (1) according to claim 6, when performing the step of obtaining a molded body by molding the mixture into a predetermined shape, setting the molding pressure to ^{1.0t / cm 2 ~1.5t / cm 2} .
Therefore, according to the invention described in the technical idea 1, it is possible to sufficiently improve the thermal conductivity while avoiding an increase in equipment cost and difficulty in manufacturing.

(2) In the sixth and seventh aspects of the present invention, in producing the granules from the mixture and molding the granules into a predetermined shape, the water content of the granules may be reduced to 0.1. % By weight to 2.0% by weight. Therefore, according to the invention described in the technical idea 2, it is possible to sufficiently improve the thermal conductivity while avoiding a decrease in the yield.

[0084]

As described in detail above, according to the first to fifth aspects of the present invention, it is possible to provide a silicon carbide / metal composite having extremely excellent heat uniformity, thermal responsiveness and shape stability. it can.

According to the sixth and seventh aspects of the present invention, it is possible to provide a method for reliably producing such a suitable composite. According to the eighth aspect of the present invention, it is possible to provide a member for a wafer polishing apparatus suitable for manufacturing a large-diameter and high-quality wafer.

According to the ninth aspect of the present invention, a large-diameter
A table for a wafer polishing apparatus suitable for manufacturing a high quality wafer can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a wafer polishing apparatus according to an embodiment of the invention.

FIG. 2 is an enlarged sectional view of a main part of a table used in the wafer polishing apparatus.

FIG. 3 is a sectional view conceptually showing the table in an enlarged scale.

FIGS. 4A, 4B, and 4C are graphs showing a particle size distribution in a silicon carbide / metal composite constituting the table.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Wafer grinding | polishing apparatus, 2 ... Table for wafer polishing apparatuses which are a kind of ceramic structures, 2a ... Polishing surface, 5 ... Semiconductor wafer, 6 ... Wafer holding plate, 6a ... Holding surface,
11A, 11B: base material, 12: cooling water channel as a fluid flow path, 21: fine silicon carbide crystals, 22: coarse silicon carbide crystals, 23: open pores.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 21/304 622 C04B 35/56 101P F-term (Reference) 3C058 AA07 BC02 CB01 CB03 DA02 DA17 4G001 BA22 BA61 BA62 BA63 BA75 BA78 BB22 BB61 BB62 BB63 BC12 BC13 BC17 BC32 BC33 BC52 BC54 BC73 BC77 BD03 BD38 BE22 BE33

Claims (9)

[Claims] 1. A silicon carbide / metal composite in which open pores are present in a porous structure composed of silicon carbide crystals and a metal is impregnated in the open pores, the average particle size of the silicon carbide crystals Is 20 μm or more, the porosity is 30% or less, and the thermal conductivity is 160 W / m · K or more,
A silicon carbide-metal composite impregnated with 15 to 50 parts by weight of metal per 100 parts by weight of silicon carbide. 2. A silicon carbide / metal composite in which open pores are present in a porous structure constituted by silicon carbide crystals and a metal is impregnated in the open pores, wherein the average particle size of the silicon carbide crystals is Is 20 μm to 100 μm,
The porosity is 5% to 30%, the thermal conductivity is 160 W / m · K or more, and 15 parts by weight or more based on 100 parts by weight of silicon carbide.
A silicon carbide / metal composite impregnated with 50 parts by weight of a metal. 3. The silicon carbide / metal composite according to claim 1, wherein 15 to 45 parts by weight of metallic silicon is impregnated with respect to 100 parts by weight of silicon carbide. 4. The silicon carbide / metal composite according to claim 1, wherein 20 to 50 parts by weight of metallic aluminum is impregnated with respect to 100 parts by weight of silicon carbide. 5. A composition containing fine silicon carbide crystals having an average particle size of 0.1 μm to 1.0 μm in an amount of 10% by volume to 50% by volume, and
2. The composition according to claim 1, wherein said silicon carbide crystal has an average particle size of 25 to 150 [mu] m in an amount of 50 to 90% by volume.
5. The silicon carbide / metal composite according to any one of items 4 to 4. 6. An open pore is present in a porous structure composed of silicon carbide crystals, and silicon carbide 1 is contained in the open pore.
15 parts by weight to 50 parts by weight of the metal is impregnated with respect to 00 parts by weight, and the average particle size of the silicon carbide crystal is 20 μm or more,
A method for producing a silicon carbide / metal composite having a porosity of 30% or less and a thermal conductivity of 160 W / m · K or more, comprising a coarse powder of α-type silicon carbide having an average particle size of 5 μm to 100 μm.
The average particle size is 0.1 μm to 1.0 μm with respect to 00 parts by weight.
A step of mixing 10 parts by weight to 100 parts by weight of the fine powder of α-type silicon carbide and uniformly mixing the mixture, a step of forming the mixture obtained in the step into a predetermined shape to obtain a molded body,
A step of firing the molded body at a temperature in the range of 1700 ° C. to 2400 ° C. to obtain a sintered body; and a step of impregnating the molded body or the sintered body with a metal. How to make the body. 7. The silicon carbide-metal composite according to claim 6, wherein the molded body contains an organic substance serving as a carbon source in an amount of 1% by weight to 10% by weight in terms of carbon weight. Manufacturing method. 8. A member used for a wafer polishing apparatus, wherein the silicon carbide / silicon carbide according to any one of claims 1 to 5 is used.
A member for a wafer polishing apparatus composed of a metal composite. 9. A table having a polished surface on which a semiconductor wafer held on a holding surface of a wafer holding plate constituting a wafer polishing apparatus is slidably contacted, according to any one of claims 1 to 5. A table for a wafer polishing apparatus, wherein each substrate is joined together in a state where a plurality of substrates made of the silicon carbide / metal composite are laminated, and a fluid flow path is provided at a joint interface between the substrates.