JPH0365564A - Production of aluminum nitride sintered compact - Google Patents

Abstract

PURPOSE:To simply and inexpensively obtain a dense aluminum nitride sintered compact by burning a formed article consisting of mixture of an aluminum- containing compound and glycine under a non-oxidizing atmosphere containing nitrogen. CONSTITUTION:A formed article consisting of an aluminum-containing compound and glycine and having prescribed form is burned under a non-oxidizing atmosphere containing nitrogen. The aluminum-containing compound is a water-soluble compound and the mixture is preferably prepared by uniformly blending the aluminum compound with glycine in a state of aqueous solution and then removing water content. The aluminum-containing compound includes at least one among aluminum polynuclear complex (e.g. basic aluminum chloride or basic aluminum lactate) and aluminum alkoxide. The formed article containing a sintering assistant may be burned.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing an aluminum nitride sintered body suitable for use as, for example, a highly thermally conductive (insulating) substrate.

[Conventional technology and problems]

BACKGROUND ART As semiconductor devices such as ICs have become more highly integrated and have higher power, electrical insulating materials with good heat dissipation properties have become required. In response to this demand, various highly thermally conductive substrates have been proposed. Among them, aluminum nitride ceramic substrates in particular are being put into practical use because they are excellent in terms of thermal conductivity, thermal expansion, electrical insulation, and the like.

This aluminum nitride ceramic main substrate is a sintered body obtained using aluminum powder.
There were problems in that aluminum nitride sintered bodies with sufficient performance were difficult to obtain and were expensive. The aluminum nitride powder used here is manufactured by direct nitriding of aluminum, carbon reduction of alumina, etc.; for example, it is difficult to obtain powder with high purity and small particle size using the direct nitriding method of aluminum. ,
The carbon reduction method for alumina has problems such as high temperatures required for the reaction and high raw material costs. As an improvement to the carbon reduction method of alumina, a method of reducing the aluminum source with a carbon-containing compound has been proposed, but it is still not sufficient in terms of reduction efficiency.

In addition, the conventional process for obtaining aluminum nitride powder is labor-intensive and requires considerable material and energy costs, making the resulting aluminum nitride sintered body expensive. ing.

[Problem to be solved by the invention]

In view of these circumstances, it is an object of the present invention to provide a method that can easily and inexpensively obtain a sufficiently sintered and dense aluminum nitride sintered body.

[Means to solve the problem]

In order to solve the above problem, the method for producing an aluminum nitride sintered body according to claim 1 includes firing a molded body of a predetermined shape made of a mixture of an aluminum-containing compound and glycine in a non-oxidizing atmosphere containing nitrogen. I have to.

In the mixture of an aluminum-containing compound and glycine used in the production method of the present invention, for example, as in the invention according to claim 2, the aluminum-containing compound is a water-soluble compound, and the aluminum-containing compound and glycine are uniformly mixed in an aqueous solution state. Examples include those obtained by drying and then removing water.

The aluminum-containing compound used in the production method of the present invention includes at least one of an aluminum polynuclear complex and an aluminum alkoxide.

In the method for producing an aluminum nitride sintered body according to the present invention, for example, as in the fourth aspect of the present invention, the molded body may contain a sintering aid and then be fired.

This will be explained in more detail below.

The aluminum-containing compound is a source of aluminum, which is the main component of aluminum nitride. Therefore, as long as it is a compound containing aluminum, it is not particularly limited, and examples thereof include aluminum nitrate, aluminum chloride, aluminum sulfate, aluminum hydroxide, aluminum lactate, alumina, aluminum polynuclear complex, aluminum alkoxide, and the like.

Examples of the aluminum polynuclear complex include basic aluminum chloride, basic aluminum lactate, and basic aluminum nitrate.

As the aluminum alkoxide, aliphatic alkoxides having 10 or less carbon atoms such as aluminum methoxide, aluminum ethoxide, aluminum propoxide, and aluminum butoxide can be suitably used. Used alone or in combination. .

Glycine functions to remove the oxygen element contained in the aluminum-containing compound in the form of CO and Cot in the aluminum nitride production reaction in the firing process.

When the aluminum-containing compound is a water-soluble compound and a mixture is obtained by uniformly mixing this and glycine in an aqueous solution state and then drying to remove water, the drying temperature is, for example, in the range of about 70 to 200°C. Appropriate.

The mixture obtained by drying in this way is in a powder state or a bulk state. In the manufacturing method of the present invention, the mixture is formed into a bottom-shaped body of a predetermined shape, but if the mixture obtained by drying is in bulk form, it is preferable to first crush and powder it and then shape it. , it may also be molded in bulk form.

The molding method may be, for example, a pressure molding method using a mold, but is not particularly limited as long as it does not cause undesirable deterioration or leakage of components.

The sintering aids contained in the molded body include alkali, etc.
Yes, there is, rare earth 7. Examples include raw salts and oxides. For example, yttrium nitrate, yttrium chloride, basic isotrium acetate, isotrium oxide, calcium nitrate, calcium chloride, calcium chloride, etc.
·, two examples are given, but are not limited to. The content of the sintering aid is 3% relative to the aluminum contained.
~ 10% sintering with addition of sintering aids.
Iminge is an aluminum-1・'nom-containing compound,! . Glycine may be mixed, \reno, ~ aqueous solution stage, or powder stage 11Pi after drying the aqueous solution, etc., and is not particularly limited.

Non-oxidizing atmosphere! : 1 is nitrogen-containing aluminum/carbon oxide; 1 is nitrogen-containing carbon oxide;
The temperature is 200°C or higher, preferably about 1400 to 2000°C. In addition, after nitriding, Example A, B, 600-70
The residual carbon in the sintered body is removed by heat treatment in an oxidizing atmosphere 'Y' at about 0°C (t: '-f).

[For production]

As in the method for crushing an aluminum nitride sintered body according to the present invention, a molded body of a predetermined shape made of an aluminum-containing compound, such as a 4-aluminum polynuclear complex or a mixture of aluminum alkoxy-4'-cyto and glycine, is heated with nitrogen. By firing in a non-oxidizing atmosphere that contains aluminum, a hollow aluminum sintered body with high purity (nitridation rate), denseness, and good thermal conductivity can be easily obtained without going through a complicated powder process.

Since glycine is a nitrogen-containing metal compound, the mixture also contains a source of stolen elements. Therefore, a local reducing atmosphere is formed, the emptying reaction is promoted from within the mixture, and empty aluminum is rapidly formed.

The aluminum-containing compound is a water-soluble compound2, and after uniformly mixing it and glycine in an aqueous solution state, water is removed (thereby, the resulting mixture is a mixture of the aluminum-containing compound and glycine on a molecular order). In this state, a more pure and homogeneous sintered body can be obtained.

〔Example〕

Specific examples will be described below.

Example 1 - Basic alk chloride,! , mix 18.glycine to 1.0% of glycine to 1.0% of ram. An aqueous solution was prepared. In addition, basic aluminum chloride, -,, ram has an aluminilla J content of A/! The content was 50% by weight in terms of s Ov, and the base content was 84%. next,
This aqueous solution was evaporated to dryness at a drying temperature of 70°C. The obtained solid material was crushed 1. After that, using a molding metal, it was made into a disk-shaped body with a diameter of 25 cm and a thickness of 3 mm, and then baked in a nitrogen atmosphere at 1900°C for 8 hours. A sintered aluminum nitride body was obtained.

Example 2 An aqueous solution was prepared by mixing basic aluminum chloride used in Example 1 with 140 parts by weight of glycine and 0.068 parts by weight of yttrium nitrate hexahydrate.゜ Again. Next, the aqueous solution of 1. ゛ was evaporated to dryness at a drying temperature of 80°C. 6. The obtained solid was crushed, and then molded into a mold with a diameter of 25 knots and a thickness of 3 mm.
□ After forming a disc-shaped compact, it was fired in a nitrogen atmosphere at 1850°C for 4 hours to obtain a sintered body of aluminum nitride and UNO.

Example 3: 0 parts of glycine per 1 coulometric part of basic aluminum lactate
．． 73 parts by weight, 0o05 ytI-lium nitrate hexahydrate
An aqueous solution was prepared by mixing the two to form an electrolyte. In addition,
Basic aluminum lactate has an aluminum content of Aβ
80. This aqueous solution was evaporated to dryness at a drying temperature of 80°C. After crushing the obtained solid,
A molded body was formed into a disk-shaped body with an iH diameter of 25 mm and a thickness of 3 mm using a molding die, and then fired in a nitrogen atmosphere at 1850° C. for 4 hours to obtain an aluminum nitride sintered body.

Example 4 - 1 coulometric part of aluminum triisopropoxide (aluminum triisopropoxide 1"J poxide), 0.50 glycine
Heavy Kyoto, yttrium nitrate 6 permanent 0.033 electric spring part, tetramethylammonium hydrooxa 1115
After stirring at room temperature for 1 hour, the solution was evaporated to dryness at a drying temperature of 80°C. After pulverizing the obtained solid material, a shaped rod was obtained in the same manner as in Example 1. After that, it was fired at a temperature of 1850° C. in a nitrogen atmosphere for 4 hours to obtain an aluminum nitride sintered body.

Example 5 - 0.27 parts by weight of glycine and 0.01 parts by weight of yttrium nitrate hexahydrate for 1 part by weight of aluminum nitrate nonahydrate.
An aqueous solution was prepared by mixing 9 parts by weight. Next, this aqueous solution was evaporated to dryness at a drying temperature of 120°C. After crushing the obtained solid material and obtaining a molded rod in the same manner as in Example 1, it was pulverized in a nitrogen atmosphere at a temperature of 1850°C for 4 hours.
The aluminum nitride sintered body was obtained by firing for several hours.

- Comparative Example 1 An aqueous solution was prepared by mixing 1 part by weight of basic aluminum chloride with 0.47 parts by weight of hexamethylenetetramine. The basic aluminum chloride used had an aluminum content of A1.0, 50% by weight in terms of conversion, and a basicity of 84%. Next, this aqueous solution was evaporated to dryness at a drying temperature of 120°C. After crushing the obtained solid, it was molded into a mold with a diameter of 25 mm.
1 piece, after making it into a disk-shaped rod with a thickness of 3 mm, 19
The aluminum nitride sintered body was obtained by firing in a nitrogen atmosphere at 00°C for 8 hours.

The density and thermal conductivity of the aluminum nitride sintered bodies of Examples 1 to 5 and Comparative Example 1 thus obtained were measured.

The measurement results are shown in Table 1.

Table 1 As shown in Table 1, the aluminum nitride sintered bodies of Examples 1 to 5 are dense sintered bodies with higher densities than those of Comparative Example 1. It is conductivity. When the sintered bodies of Examples 1 to 5 were subjected to X-ray analysis, almost no peak indicating the presence of unnitrided residual /l□○ was detected, but when the sintered bodies of Comparative Example 1 were subjected to X-ray analysis. However, unnitrided residual A7! A peak indicating the presence of xOs was clearly detected.

〔Effect of the invention〕

As described above, in the method for producing an aluminum nitride sintered body according to the present invention, a dense and highly thermally conductive sintered body can be directly produced without passing through the state of aluminum nitride powder. Therefore, a substrate with excellent high thermal conductivity (!f! on the edge) can be obtained easily and inexpensively.

In addition, in this production method, if the mixture is obtained by uniformly mixing the aluminum-containing compound and glycine in an aqueous solution state and then removing water, the aluminum-containing compound and glycine will be mixed by -4-. Mixed with each other/) C1, Ninaha °)) Nime, Yori: % 4'! '
Skin. A homogeneous sintered body should be obtained at L09, which is 3.

Claims (1)

[Scope of Claims] 1. A method for producing an aluminum nitride sintered body, which comprises firing a molded body of a predetermined shape made of a mixture of an aluminum-containing compound and glycine in a non-oxidizing atmosphere containing nitrogen. 2. The method for producing an aluminum nitride sintered body according to claim 1, wherein the aluminum-containing compound is a water-soluble compound, and the mixture is obtained by uniformly mixing this and glycine in an aqueous solution state and then removing water. 3. The method for producing an aluminum nitride sintered body according to claim 1 or 2, wherein the aluminum-containing compound is at least one of an aluminum polynuclear complex and an aluminum alkoxide. 4. The method for producing an aluminum nitride sintered body according to any one of claims 1 to 3, wherein the molded body contains a sintering aid.