JP2563782B2 - Method for manufacturing silicon carbide based jig for semiconductor manufacturing - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a semiconductor manufacturing jig, and more particularly to a silicon wafer which is housed in a high temperature furnace for manufacturing a semiconductor device for the electronic industry. The present invention relates to a method for manufacturing a semiconductor manufacturing jig used as a support base or the like.

(Prior Art) Conventionally, as a jig for manufacturing a semiconductor for this kind of electronic industry, for example, a jig made of quartz, a carbon / silicon carbide composite in which a silicon carbide coating is formed on the surface of a graphite base material, or silicon carbide is used. BACKGROUND ART A composite body or the like in which a molded body is filled with metallic silicon is known, and is used according to each application.

By the way, the above-mentioned quartz jig for semiconductor manufacturing has poor heat resistance and is liable to be softened and deformed. In addition, a carbon-silicon carbide composite having a silicon carbide coating formed on the surface of a graphite base material needs to be purified by a method such as high-temperature heat treatment of the graphite base material in a halogen gas atmosphere in advance. Not economical because it costs money.

Further, a composite obtained by filling the above silicon carbide molded body with metallic silicon is disclosed in, for example, Japanese Patent Application Laid-Open No. 51-85374, "Process tube, paddle of a size and shape that can be inserted therein, and the paddle. At least one boat-shaped vessel, said process tube, paddle and boat-shaped vessel being based on a sintered silicon carbide matrix containing 5 to 30% by weight of high-purity silicon metal,
A semiconductor diffusion furnace in which the silicon metal provides gas impermeability to the tube, paddle and boat. The invention according to "is disclosed.

(Problems to be Solved by the Invention) However, the sintered silicon carbide matrix described in JP-A-51-85374 is recrystallized silicon carbide, and relatively coarse particles of silicon carbide are used as a starting material. Therefore, it is difficult to manufacture a sintered body having a large surface roughness, particularly a complicated shape, and high dimensional accuracy, without performing special machining.

By the way, since a semiconductor manufacturing jig for the electronic industry is mainly used for handling high-purity products such as semiconductors, it has high purity, no product contamination, and excellent heat resistance. Besides being important, since it is used for applications where heating and cooling are frequently repeated, it is preferable that it has excellent thermal conductivity and thermal shock resistance. It has been difficult to provide an excellent semiconductor manufacturing jig at a particularly low cost.

In addition, when trying to manufacture a semiconductor manufacturing jig with a complicated shape, each of the above problems is further highlighted, so manufacturing a semiconductor manufacturing jig with a shape that can improve the manufacturing efficiency of semiconductor elements It was extremely difficult to do.

Therefore, the present inventor can form a complicated shape as compared with the conventionally known jigs for semiconductor manufacturing as described above, and is particularly excellent in thermal conductivity, and has good thermal uniformity and fast thermal response. As a result of various studies for the purpose of providing a semiconductor manufacturing jig capable of obtaining the above, it is possible to effectively utilize the above-mentioned metallic silicon and bond silicon carbide members to each other to obtain a high-strength and complicated shape. The present invention has been completed by newly discovering that the above semiconductor manufacturing jig can be easily manufactured.

That is, it is an object of the present invention that, by effectively utilizing the properties of metallic silicon, it is possible to obtain excellent thermal conductivity, good soaking property, and fast thermal response, as well as a semiconductor device. To provide a method for manufacturing a jig for manufacturing a semiconductor having a complicated shape, which can improve the manufacturing efficiency.

(Means for Solving the Problems) In order to achieve the above object, the means adopted by the present invention is that “a silicon carbide powder having an average particle diameter of 5 μm or less is molded to have a desired shape and a bulk specific gravity. Form a plurality of green compacts of 1.12 to 2.0 g / cm ³ , and these green compacts are sintered in a non-oxidizing atmosphere to form a silicon carbide member having a three-dimensional network skeleton. The silicon carbide members are combined so that the mutual clearance is 3 mm or less, and the combined silicon carbide members are filled with 45 to 135 parts by weight of metallic silicon with respect to 100 parts by weight of silicon carbide. A method of manufacturing a silicon carbide-based jig for semiconductor manufacturing, which comprises mutually bonding with silicon. "

FIG. 1 shows a wafer board which is an example of a semiconductor manufacturing jig (10) according to the present invention. This semiconductor manufacturing jig (10) is formed by combining a plurality of silicon carbide members (11) and adhering them to each other with metallic silicon. Hereinafter, this manufacturing method will be described.

 First, a green form is formed.

Fill the mold with powder of silicon carbide having an average particle size of 5 μm or less,
Compression molding is performed to form green molded bodies each having a desired shape. These green forms have a bulk specific gravity of 1.12 to 2.0 / cm.
³ , having an open porosity of 38-65% by volume.

According to the present invention, it is important to produce a high-strength porous body having a low density and excellent handleability as compared with a conventionally known porous silicon carbide sintered body. When molding the green body, it is advantageous to use silicon carbide powder as a starting material, which is obtained by uniformly dispersing silicon carbide powder in a dispersion medium together with a peptizer and then freeze-drying the same.
When molding a green body by a casting method, it is advantageous to use a suspension in which silicon carbide powder is uniformly dispersed together with a peptizer in a dispersion medium liquid as a starting material.

The reason is that since silicon carbide powder has a strong cohesive property, usually it is easy to form secondary particles in which a large number of individual particles are in close contact with each other, and therefore such a silicon carbide powder is used as a starting material without any dispersion treatment. When used, the three-dimensional network structure of the porous body obtained by the coarsening of crystal grains in the unit of secondary particles tends to have a relatively coarse structure, and it is difficult to obtain a porous body having a low density and high strength. Met. However, a green molded body obtained by casting and molding using a green molded body and a suspension formed by pressure molding using silicon carbide powder that has been uniformly dispersed with a deflocculant in a dispersion medium liquid as described above and then freeze-dried. In each case, since it is possible to produce a green compact in which individual particles of silicon carbide powder exist in a very uniformly dispersed state, it is possible to develop a three-dimensional network structure of crystals in an extremely fine and uniform manner. This is because it is possible to manufacture a porous body having high density and high strength.

According to the present invention, various kinds of the dispersion medium can be used, but those used particularly in the case of freeze-drying are preferably those having a melting point in the range of -5 to 15 ° C. Of these, it is advantageous to use at least one selected from benzene and cyclohexane or water.

According to the present invention, as a means for uniformly dispersing the silicon carbide powder in the dispersion medium liquid, a dispersing means such as a vibration mill, an attritor, a ball mill, a colloid mill or a high speed mixer capable of giving a strong shearing force is used. Is advantageous.

According to the present invention, the deflocculant used when uniformly dispersing the silicon carbide powder in the dispersion medium liquid is, for example, a fatty acid amine salt, an aromatic amine salt or a heterocyclic ring when the dispersion medium liquid is organic. Amine salts, cationic surfactants such as polyalkylene polyamine derivatives, nonionic surfactants such as ester type, ester ether type, ether type and nitrogen-containing type are effective, and when the dispersion medium liquid is water, for example, Inorganic peptizers such as ammonium oxalate and aqueous ammonia, and organic peptizers such as diethylamine, monoethylamine, pyridine, ethylamine, tetramethylammonium hydroxide and monoethanolamine are effective.

According to the present invention, when the suspension in which the silicon carbide powder is uniformly dispersed in the dispersion medium is freeze-dried, the suspension is sprayed into an atmosphere maintained at a temperature lower than the melting point of the dispersion medium. Then, it is advantageous to freeze immediately.

By the way, there are α-type, μ-type and amorphous types of the silicon carbide crystal system. Among them, the β-type has a relatively high average particle size of 5 μm or less and is easily obtained. Since a porous body having a high strength can be easily produced, it can be advantageously used, and it is particularly preferable to use a silicon carbide powder containing 50% by weight or more of β-type silicon carbide.

According to the invention, the bulk specific gravity of the green form is 1.12 to 2.0 g.
/ cm ³ is required. The reason is that the bulk specific gravity is less than 1.12 g / cm ³ because there are few bonding sites between silicon carbide particles, and the resulting porous body has low strength and poor handleability, while 2.0 g / cm ³ If it is larger, it is difficult to produce a porous body having a large open porosity, which is the object of the present invention, and a jig for semiconductor production having high thermal conductivity (10).
Because it becomes difficult to manufacture.

According to the invention, this is necessary. The reason is that if the temperature is lower than 1400 ° C, it is difficult to sufficiently develop the neck that connects the grains to each other, and a porous body having high strength cannot be obtained, while higher than 2100 ° C. That is, among the grown necks, a neck smaller than a certain size has a necked shape or disappears in a remarkable case, and the strength is rather lowered.

 Sinter the green body.

According to the present invention, the green body comprises at least one selected from the group consisting of argon, helium, neon, nitrogen, hydrogen and carbon monoxide in a non-oxidizing atmosphere that does not oxidize silicon carbide. Baking at a sintering temperature of 1400 to 2100 ° C in a gas atmosphere or in a vacuum. The fired silicon carbide member (11) has an average bending strength of 5 kg / mm ² or more.

According to the invention, it is advantageous that the green body is fired in a non-oxidizing atmosphere without substantial shrinkage. The reason is that shrinkage at the time of sintering is desirable in order to improve the strength of the porous body, but when shrinking by firing, the open porosity is decreased, and the pores are apt to become independent pores, which makes it difficult to fill the metal silicon. This is because it is difficult to manufacture a porous body having high dimensional accuracy by causing firing shrinkage.

According to the present invention, in order to obtain a porous body which can be easily filled with metallic silicon and has high dimensional accuracy, the firing shrinkage rate during sintering without substantially shrinking can be 2% or less. It is preferable that it is 1% or less.

Further, according to the present invention, it is advantageous to suppress volatilization of silicon carbide from the green body when firing the green body. The reason is that by suppressing volatilization of silicon carbide from the green body, a neck connecting the silicon carbide particles to each other can be sufficiently developed, and particularly high strength and excellent handleability are provided. When producing a porous body, it is advantageous to control the volatilization rate of silicon carbide to be 5% by weight or less.

As a method of suppressing volatilization of silicon carbide from the green body, a method of inserting the green body into a heat-resistant container capable of blocking the invasion of outside air is effective, and as the heat-resistant container, It is preferable to use a heat-resistant container made of a material such as graphite or silicon carbide.

 A silicon carbide member (11) is combined.

These silicon carbide members (11) are combined in a predetermined positional relationship. In this case, the mutual clearance is 3 mm or less.

Next, the combined silicon carbide members are filled with metallic silicon.

According to the present invention, it is necessary to fill the metallic silicon in an amount of 45 to 135 parts by weight with respect to 100 parts by weight of silicon carbide forming the jig. The reason why the metallic silicon is filled is that the metallic silicon has good compatibility with silicon carbide, and not only can the strength be improved by filling the metallic silicon into the open pores of the porous body, but Since it has excellent conductivity, by filling the open pores of the porous body with metallic silicon, a jig for semiconductor manufacturing (10) having high thermal conductivity and gas impermeability can be formed. Because. Further, the reason why it is advantageous to set the filling amount of the metal silicon to 45 to 135 parts by weight is because the semiconductor manufacturing jig (10) having high thermal conductivity when the filling amount of the metal silicon is less than 45 parts by weight. On the other hand, the upper limit of the filling amount is determined by the open porosity of the porous body. More preferably, the filling amount of the metallic silicon is 55 parts by weight or more.

As a method for filling the open pores of the porous body with the metal silicon, a method of heating and melting the metal silicon for impregnation or dispersing finely divided metal silicon in a dispersion medium liquid, and the dispersion liquid is used as the porous body. After impregnating and drying, the method of heating above the melting temperature of metallic silicon can be applied.

 The silicon carbide member (11) is bonded.

When the silicon metal filled in the open pores of each silicon carbide member (11) and the metal silicon filled in the space formed between the silicon carbide members (11) are sintered, each silicon carbide member (11) Are firmly bonded to each other to form a semiconductor manufacturing jig (10).

(Example) Below, this invention is demonstrated with an Example and a comparative example.

Example 1 The silicon carbide powder used as a starting material was a silicon carbide powder in which 97.5% by weight was β-type crystals and the balance was substantially 2H-type crystals. 0.12% by weight of free carbon, 0.37% by weight of oxygen, Contains 1.2 x 10 ^-4 wt% iron, 1.4 x 10 ^-4 wt% calcium, 8 x 10 ^-5 wt% sodium, 1 x 10 ^-5 wt% potassium and traces of aluminum, 1.1 μm
Had an average particle size of.

5 parts by weight of polyvinyl alcohol, 0.3 parts by weight of monoethanolamine and 1 part of water based on 100 parts by weight of the silicon carbide powder.
00 parts by weight were blended, mixed in a ball mill for 5 hours and then freeze-dried.

An appropriate amount of this dry mixture was sampled and granulated, and then a green compact was molded using a hydrostatic press at a pressure of 1300 kg / cm ² . The green form had a plate shape with a vertical length of 200 mm and a thickness of 10 mm and a density of 1.73 g / cm ³ (54% by volume).

The green molded body was inserted into a graphite crucible and sintered in a primarily argon gas atmosphere at 1 atm using a Tammann type sintering furnace. During the temperature raising process, the temperature was raised to 2000 ° C. at 450 ° C./hour and kept at the maximum temperature of 2000 ° C. for 15 minutes. The partial pressure of CO gas during sintering was controlled by appropriately adjusting the argon gas flow rate so that the room temperature to 1700 ° C was 80 Pa or less and the temperature higher than 1700 ° C was within 300 ± 50 Pa.

The obtained sintered body had a density of 1.70 g / cm ³ and an open porosity of 47.
Porous material with volume% and β-silicon carbide content of 92% by weight
The balance was mainly 4H type and 6H type α-type silicon carbide.
Also, this crystal structure has a three-dimensional structure in which block-shaped silicon carbide crystals are intricately entangled and combined with each other by a relatively thick neck when observed by a scanning electron microscope. The average bending strength of this sintered body is as high as 13.8 Kg / mm ² within the range of 0.3 ± 0.1% with respect to the direction of 3 × 10 ^-4 % by weight of aluminum, 6 × 10 ^-4 wt% iron and 4 x 10 ^-4
It contained nickel by weight. The contents of chromium, calcium, and copper were all trace amounts, and the contents of sodium and potassium were all less than 1 × 10 ⁻⁴ wt%.

Then, a plurality of silicon carbide members (11) of different types (shapes) made of the above silicon carbide sintered body are prepared.

Next, 100 parts by weight of metallic silicon powder having an average particle size of 20 μm and a purity of 99.9999% by weight or more and a 5% acrylic acid ester / benzene solution 6 are formed on the surface of each of the silicon carbide members (11).
A slurry in which 0 part by weight was mixed was applied, and 380 g of metallic silicon was coated on the surface. The silicon carbide member (11) coated with this metallic silicon was heated in an argon gas stream at a temperature rising rate of 450 ° C / hour to obtain a maximum temperature of 1450 ° C.
The temperature was maintained for about 1 hour, and the metallic silicon coated on the surface of the silicon carbide member (11) was permeated into the silicon carbide member (11) to obtain a silicon carbide-based composite.

The obtained silicon carbide-based composite had a porosity of 2% and had gas impermeability, and the dimensions were only 0.03 mm larger than before it was filled with metallic silicon. Was as strong as 32.1 Kg / mm ^2, and the thermal conductivity was extremely good at 0.23 cal / cm sec ° C, and it was confirmed that it was extremely excellent for use as a semiconductor manufacturing jig (10).

The respective silicon carbide members (11) were bonded to each other, the space formed by the respective silicon carbide members (11) was filled with the above-mentioned metallic silicon, and the whole thereof was again fired. As a result, the intended semiconductor manufacturing jig (10) was obtained.

Comparative Example 1 Same as Example 1, but the silicon carbide powder used in Example 1 as a starting material and a commercially available α-type silicon carbide (GC # 240
A silicon carbide member was manufactured by using a mixed powder in which an average particle size of 80 μm) was mixed in a weight ratio of 3: 7, and then impregnated with metallic silicon to obtain a silicon carbide based composite.

The silicon carbide member has a density of 2.37 g / cm ³ and an open porosity of 2
It had a relatively low strength of 6% by volume and an average bending strength of 5.2 kg / mm ² . The silicon carbide-based composite obtained by further impregnating metallic silicon had a porosity of 1.7% and was gas impermeable, but the content of metallic silicon was 24 parts by weight per 100 parts by weight of silicon carbide. And the thermal conductivity is 0.21 cal / cm s
It was not so good at ec ℃.

Example 2 Similar to Example 1, except that the silicon carbide powder used in Example 1 as a starting material and a commercially available α-type silicon carbide powder (GC #
6000) is crushed, and further refined and particle size classified to obtain a silicon carbide member (11) using a mixed powder in which silicon carbide powder (average particle size 1.2 μm) is mixed in various proportions, and then the silicon carbide member is prepared. (11) was placed in a graphite crucible and
99.9999% by weight or more of massive metallic silicon was placed around the silicon carbide member (11) and then heated at 1450 ° C. to produce a silicon carbide matrix composite having a substrate impermeability.

The properties of the obtained silicon carbide member (11) and silicon carbide-based composite are shown in Table 1.

As can be seen from Table 1, the silicon carbide member (11) using silicon carbide powder having a high β-type silicon carbide powder mixing ratio as a starting material had excellent strength for its density.

Example 3 A silicon carbide composite body was produced in the same manner as in Example 1 except that a green compact having different bulk specific gravities was produced by changing the molding pressure. The properties of the obtained silicon carbide member (11) and silicon carbide based composite are shown in Table 2.

As can be seen from Table 2, the silicon carbide member (1
1) has excellent strength even at low density.

Example 4 For 100 parts by weight of the silicon carbide powder used in Example 1,
3 parts by weight of polyacrylic acid ester, 0.4 parts by weight of tetramethylammonium hydroxide and 60 parts by weight of water were mixed and mixed in a ball mill for 10 hours, then cast-molded to give an outer diameter of 60 mm,
A tubular molded body having an inner diameter of 45 mm, a length of 300 mm and a density of 1.63 g / cm ³ was obtained.

Then, a silicon carbide-based composite body was produced under the same conditions as in Example 1.

The properties of the obtained silicon carbide member (11) and silicon carbide-based composite are shown in Table 1.

(Effects of the Invention) As described above, in the present invention, as illustrated in each of the above-described examples, "silicon carbide powder having an average particle diameter of 5 μm or less is molded to have a desired shape and a bulk shape. Specific gravity 1.12 to 2.
0 g / cm ³ ) of plural green compacts are formed, and these green compacts are sintered in a non-oxidizing atmosphere to form a silicon carbide member having a three-dimensional network skeleton. Combined so that the mutual clearance is 3 mm or less,
The combined silicon carbide member is filled with 45 to 135 parts by weight of metallic silicon with respect to 100 parts by weight of silicon carbide, and the silicon carbide members are bonded to each other by the metallic silicon. Method of manufacturing ingredients. ”Has a feature in its configuration, and therefore, even a semiconductor manufacturing jig having a complicated shape can be easily manufactured by combining and adhering a plurality of silicon carbide members. By effectively utilizing the properties of silicon, it is possible to obtain excellent thermal conductivity, good thermal uniformity, and fast thermal response. That is, this semiconductor manufacturing jig (10) is a silicon carbide-based composite body having a porous silicon carbide sintered body as a skeleton, and is excellent in wear resistance, and also excellent in thermal conductivity and thermal shock resistance. Therefore, it can be applied extremely advantageously even to applications where heating and cooling are frequently repeated, and is extremely useful in industry.

[Brief description of drawings]

FIG. 1 is a perspective view of a semiconductor manufacturing jig according to the present invention, and FIG.
The drawing is a partially enlarged sectional view taken along the line II-II in FIG. Explanation of symbols 10 …… Semiconductor manufacturing jig, 11 …… Silicon carbide member.

Claims (2)

(57) [Claims] We claim: 1. average particle size by molding the following silicon carbide powder 5 [mu] m, bulk density without the respective desired shape 1.12~2.0g / cm ³
A plurality of green compacts are formed, and these green compacts are sintered in a non-oxidizing atmosphere to form a silicon carbide member having a three-dimensional network skeleton. Is 3 mm or less, and the combined silicon carbide members are filled with 45 to 135 parts by weight of metallic silicon with respect to 100 parts by weight of silicon carbide, and the silicon carbide members are bonded to each other with metallic silicon. A method of manufacturing a silicon carbide-based jig for manufacturing a semiconductor, which is characterized. 2. The method for producing a silicon carbide based jig for semiconductor production according to claim 1, wherein the silicon carbide powder contains at least 50% by weight of β-type crystal silicon carbide.