JPH0365565A - Production of aluminum nitride sintered compact - Google Patents

Abstract

PURPOSE:To simply and inexpensively obtain dense aluminum nitride by burning a formed article consisting of a mixture of an aluminum-containing compound and saccharide under non-oxidizing atmosphere. CONSTITUTION:A formed article consisting of a mixture of an aluminum- containing compound and saccharides and having prescribed form is burned under non-oxidizing atmosphere containing nitrogen. The aluminum-containing compound is water soluble compound and the mixture is preferably prepared by uniformly blending the aluminum-containing compound with saccharides in a state of aqueous solution and then removing water content. The aluminum- containing compound includes at least one among an aluminum polynuclear complex and aluminum alkoxide (e.g. preferably <=10C aliphatic alkoxide such as aluminum methoxide or aluminum ethoxide). Although as the saccharides, e.g. monosaccharides such as D-glucose or D-fructose methoxide or disaccharides such as D-saccharose or D-maltose are preferably used, oligosaccharides or polysaccharides can be also preferably used when these saccharides are water soluble.

Description

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

[Conventional technology and problems]

BACKGROUND OF THE INVENTION As semiconductor devices such as ICs have become more highly integrated and have more 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 these, 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 substrate is a sintered body obtained using aluminum powder. However, conventionally,
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 produced by direct nitriding of aluminum, carbon reduction of alumina, etc. However, for example, it is difficult to obtain powder with high purity and small particle size using the direct nitriding method of aluminum. can be,
Alkusu's carbon reduction method has problems such as the high temperature required for the reaction and the high cost of raw materials. 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.

[Problems to be Solved by the Invention] In view of the above circumstances, the present invention aims to provide a method that can easily and inexpensively obtain a sufficiently sintered and dense aluminum nitride sintered body. Take it as a challenge.

[Means to solve the problem]

In order to solve the above problem, in the method for producing an aluminum nitride sintered body according to claim 1, a molded body of a predetermined shape made of a mixture of an aluminum-containing compound and a saccharide is fired in a non-oxidizing atmosphere containing nitrogen. I try to do that.

As for the mixture of the aluminum-containing compound and the saccharide 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 the saccharide are uniformly mixed in an aqueous solution state. After mixing with
or, as in the invention according to claim 3, the saccharide is a water-soluble compound, and the aluminum-containing compound is uniformly mixed in an aqueous solution state, and then the water is removed. Here's what I got.

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 fifth aspect of the invention, a sintering aid may be added to the molded body before firing.

This will be explained in more detail below.

The aluminum-based 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, but examples include aluminum nitrate, aluminum chloride, aluminum sulfate, aluminum hydroxide, aluminum lactate, alumina, aluminum polynuclear complex, alkium alkoxide, etc. There is.

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

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

The saccharide functions to remove the oxygen element contained in the aluminum-containing compound in the form of co and cotO in the reaction for producing aluminum nitride in the firing process. Specifically, preferred sugars include monosaccharides such as D-glucose, D-fructose, D-mannose, and D-xylose, and bicyclics such as D-sasocalose, D-maltose, and D-lactose. However, the present invention is not limited to this, and water-soluble oligosaccharides (trisaccharides or higher) and polysaccharides with higher molecular weights can also be suitably used. Of course, not only water-soluble saccharides but also polysaccharides with poor water solubility such as starch and cellulose can be used.

The aluminum-containing compound is a water-soluble compound and 1:
When obtaining a mixture by mixing and diluting water-soluble saccharides in an aqueous solution state for one day and then drying to remove water, the appropriate drying temperature is, for example, in the range of 80 to 200°C. be.

The mixture obtained by drying in this way is in a powder state or t4! ,,is in bulk state. In the manufacturing method of the invention, the mixture is divided into a predetermined shape (12) into a molded body, but if the mixture obtained by drying is in bulk, it is first pulverized and powdered. It is preferable to do this, but it is also possible to mold it in bulk (c).

The molding method may be 1, for example, a FE molding method using a molding machine, but is not particularly limited as long as it does not cause deterioration or leakage.

Examples of the sintering aid contained in the compact include salts and oxides of alkaline earth or rare earth elements. For example, specific examples include yttrium nitrate, yttrium chloride, yttrium chloride, basic yttrium acetate, yttrium hexoxide, calcium nitrate, calcium chloride, calcium oxide, etc., but are not limited thereto. In addition, the content of the sintering aid is preferably about ζ3-10% by weight based on the aluminum content and kram. , or a powder stage after drying an aqueous solution, and is not particularly limited.

Non-oxidizing atmosphere and 1. In this case, an atmosphere of argon containing nitrogen, mono-carbon oxide containing nitrogen, nitrogen, ammonia, or the like is used. Firing temperature is 1200℃ or higher
, preferably about 1400 to 2000°C. 7. After nitriding, as in Example A, residual carbon in the sintered body may be removed by further heat treatment in an oxidizing atmosphere at about 600=700°C.

[For production]

Method for producing an aluminum nitride sintered body according to the present invention ω
When a molded body of a predetermined shape made of an aluminum-containing compound, such as an aluminum polynuclear complex or a mixture of aluminum alkoxide and saccharide, is fired in a non-oxidizing atmosphere containing nitrogen, it has a high purity (nitriding rate) and is dense and heat-resistant. An aluminum nitride sintered body with good conductivity can be easily obtained without going through a complicated powder process.7 To obtain the mixture, aluminum-containing compounds and sugars are uniformly mixed in an aqueous solution state and then After that, when removing water, it is necessary to remove a small amount of aluminum-containing compounds and IJm species (if one of them is water-soluble, the aluminum-containing compound and sugars will be mixed (in a state of two),
Than! A homogeneous sintered body with a high @ standard can be obtained.

It is even more preferable if both the allenium-containing compound and the saccharide are water-soluble.

〔Example〕

Specific examples will be described below.

Example 1 - An aqueous solution was prepared in which 1 coulometric part of basic aluminum chloride was mixed with gluco-X in an amount of 60 parts gluco-X (in addition, basic aluminum chloride, -, Ram is
Aluminum content is A7! *(') The content was 50% by weight in terms of a and the basicity was 84%.

Next, this aqueous solution was dried in a drying oven at 120°C. The obtained solid was first pulverized, and then made into a disc-shaped molded product with a diameter of 25 mm and a thickness of 3 eggs using a mold, and then baked in a V atmosphere at 1900°C for 8 hours. An aluminum nitride sintered body was obtained.

Example 2 Based on the basic aluminum chloride content used in Example 1, the amount of D-fulx 1--ose was 0.60 parts by coul, and the amount of yttrium nitrate hexahydrate was 0.068 ffilt.・
An aqueous solution containing sea urchin was prepared. Next, this aqueous solution was evaporated to dryness at a drying temperature of 120°C. After crushing the obtained solid material, it was made into a disk-shaped body with a diameter of 25 mm and a thickness of 3 mm using a molding machine, and then baked in a nitrogen atmosphere at 1850 ° C. for 4 hours. A flower aluminum sintered body was obtained.

Example 3 - 0.44 parts by weight of D-glucose and 0.44 parts by weight of yttrium nitrate hexahydrate per 1 coulometric part of basic aluminum lactate.
An aqueous solution was prepared by mixing 0.05 parts by weight. In addition, basic aluminum lactate has an aluminum content of 37% by weight in terms of Al z Os, and a lactic acid content of 5% by weight.
6% was used. Next, this aqueous solution was evaporated to dryness at a drying temperature of 100°C. The obtained solid matter was
After pulverizing, use a mold to create a mold with a diameter of 25 mm and a thickness of 3 mm.
After forming an n+ disc-shaped molded body, it was fired in a nitrogen atmosphere at 1850° C. for 4 hours to obtain a sintered body mainly consisting of aluminum nitride.

Example 4 1 part by weight of basic aluminum chloride used in Example 1 was mixed with 0.60 part by weight of D-saniroku loin and 0.068 part by weight of yttrium nitrate hexahydrate. An aqueous solution was prepared. Next, this aqueous solution was evaporated to dryness at a drying temperature of 110°C. The obtained solid material was first pulverized, and then formed into a disc-shaped body with a diameter of 25 mm and a thickness of 3 m using a mold, and then fired in a nitrogen atmosphere at 1850°C for 4 hours to undergo nitriding. An aluminum sintered body was obtained.

Example 5 - 0.55 parts of soluble starch (manufactured by Nacalai Tesque) was added to 1 part by weight of basic aluminum chloride used in the example process.
An aqueous solution was prepared by mixing yttrium nitrate hexahydrate in an amount of 0.068 part by weight. Next, this aqueous solution was evaporated to dryness at a drying temperature of 180°C. The obtained solid material was first pulverized, and then made into a disc-shaped molded product with a diameter of 25 m and a thickness of 3 H using a molding die.
The aluminum nitride sintered body was obtained by firing in a nitrogen atmosphere at 50° C. for 4 hours.

Example 6 - 1 part by weight of basic aluminum chloride used in Example 1 was added to an aqueous solution containing 0.068 parts by weight of yttrium nitrate hexahydrate, and 0.0% microcrystalline cellulose (made by Nacalai Tesque). 55 parts by weight were suspended, pressed down and evaporated to dryness at a drying temperature of 150°C. The obtained solid matter was
After pulverizing, use a mold to create a mold with a diameter of 25 m and a thickness of 3 m.
After forming the molded body into a disc-shaped body having a diameter of m, it was fired in a nitrogen atmosphere at 1850° C. for 4 hours to obtain an aluminum nitride sintered body.

Example 7 - 1 part by weight of aluminum triisopropoxide (aluminum triisopropoxide), 0.2 parts by weight of D-glucose
9 parts by weight, 0.033 parts by weight of yttrium nitrate hexahydrate, 15 parts by weight of tetramethylammonium hydroxide
After stirring at room temperature for 1 hour, the solution was evaporated to dryness at a drying temperature of 120°C. After pulverizing the obtained solid, a molded body was obtained in the same manner as in Example 1, and then fired at a temperature of 1850° C. in a nitrogen atmosphere for 4 hours to obtain an aluminum nitride sintered body.

Example 8 - 0.16 parts by weight of D-glucose and 0 parts by weight of yttrium nitrate hexahydrate for 1 part by weight of aluminum nitrate nonahydrate.
．． An aqueous solution was prepared by mixing 0.019 parts by weight. Next, this aqueous solution was evaporated to dryness at a drying temperature of 120°C. The obtained solid was pulverized and a molded body was obtained in the same manner as in Example 1, and then fired at a temperature of 1850° C. in a nitrogen atmosphere for 4 hours to obtain an aluminum nitride sintered body.

- 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 hexamethylenetetra. In addition, the aluminum content of basic aluminum chloride is AIt.

The content was 50% by weight in terms of 8% and the basicity was 84%. Next, this aqueous solution was evaporated to dryness at a drying temperature of 120°C. The obtained solid material was first pulverized, and then made into a disc-shaped molded product with a diameter of 25 mm and a thickness of 3 nm using a molding die, and then fired in a nitrogen atmosphere at 1900°C for 8 hours to form an aluminum nitride. A sintered body of aluminum was obtained.

The density and thermal conductivity of the aluminum nitride sintered bodies of Examples 1 to 8 and Comparative Example 1 thus obtained were measured.

The measurement results are shown in Table 1.

Example 1-) The perforated aluminum sintered body of 3 was
As shown in the table, it is a dense sintered body with a higher density than that of Comparative Example 1, and has a high purity.
Thermal conductivity is ζ''. The sintered bodies of Examples 1-8 were subjected to X-ray analysis (
7. l・, 6ro, unnitrided residual AI! t.

, but an X-ray analysis of the sintered body of Comparative Example 1 revealed that unperforated residual A
A beak indicating the presence of N*O was clearly detected.

〔Effect of the invention〕

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

In addition, in this manufacturing method, after uniformly mixing a water-soluble aluminum-containing compound and water-soluble bran bran in an aqueous solution state, the water is removed and the mixture is obtained by straining. Since the contained compounds and saccharides are sufficiently mixed, a highly pure and homogeneous sintered body can be obtained.

5 Sanko 1 Mizo → ~ 1 Sale Ne Nihonne 1r2 1 NiF Nisho 2 (self-motivated) October 6, 1999

Claims (1)

[Scope of Claims] 1. A method for producing an aluminum nitride sintered body, in which a molded body of a predetermined shape made of a mixture of an aluminum-containing compound and a saccharide is fired 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 saccharides 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 saccharide is a water-soluble compound, and the mixture is obtained by uniformly mixing this and the aluminum-containing compound in an aqueous solution state and then removing water. 4. The method for producing an aluminum nitride sintered body according to any one of claims 1 to 3, wherein the aluminum-containing compound is at least one of an aluminum polynuclear complex and an aluminum alkoxide. 5. The method for producing an aluminum nitride sintered body according to any one of claims 1 to 4, wherein the molded body contains a sintering aid.