JPH03211046A - Setter for baking aluminum nitride ceramics - Google Patents

Abstract

PURPOSE:To eliminate the possibility of the diffusion of impurity and to repeatedly use a setter without generating creep at high temp. by coating a carbon base material with aluminum nitride or boron nitride due to the synthesis from a gaseous phase. CONSTITUTION:As the base material of a setter, an inexpensive carbon base material generating no high temp. creep is used. Then, by coating the surface of the carbon base material with aluminum nitride or boron nitride due to the synthesis from a gaseous phase by a CVD process, the setter for baking aluminum nitride ceramics can be obtained. Since the carbon base material almost generates no high temp. creep, the repeated use life of the setter can be extended in the baking of aluminum nitride ceramics and, since aluminum nitride or boron nitride covering the carbon base material is stable at high temp., there is no possibility such that the setter is bonded to aluminum nitride ceramics or oxidized at the time of the baking of aluminum nitride ceramics.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a setter used when firing aluminum nitride ceramics.

[Conventional technology]

In recent years, as semiconductor devices such as ICs have become more highly integrated and have more power, electrically insulating materials with good heat dissipation properties have become required. sexual 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. When firing an aluminum nitride ceramic substrate, a setter is used to hold the fired product, and this setter is generally made of aluminum oxide (A1203). However, aluminum nitride ceramics (AIN) is difficult to sinter and requires a sintering aid such as Y 20 or CaO, and also requires a high sintering temperature of 1800° C. or higher. For this reason, the aluminum oxide setter is not suitable for use because it reacts with aluminum nitride ceramics to cause oxidation and adhesion, and also tends to cause creep due to high temperatures, making it impossible to use repeatedly. Therefore, a setter made of boron nitride (BN), which has excellent properties against these, is used as a setter for firing aluminum nitride ceramics.

[Problem to be solved by the invention]

However, boron nitride setters are made by sintering boron nitride, but the raw material, boron nitride powder, is expensive and difficult to sinter, so sintering of B2O3, CaO, etc. There is also the problem of high prices due to the addition of auxiliary agents and the need for firing methods such as hot pressing, and the inclusion of impurities other than boron nitride is unavoidable. When firing the ceramic, diffusion occurs into the aluminum nitride ceramic, resulting in problems such as uneven firing and warping of the aluminum nitride ceramic substrate. The present invention has been made in view of the above points, and is inexpensive, and there is no risk of oxidizing aluminum nitride ceramics, adhering to aluminum nitride ceramics, or diffusing impurities into aluminum nitride ceramics. In addition, it is an object of the present invention to provide a setter for firing aluminum nitride ceramics that does not cause creep at high temperatures and can be used repeatedly and has a long life.

[Means to solve the problem]

The setter for firing aluminum nitride ceramics according to the present invention is characterized in that a carbon base material is coated with aluminum nitride or boron nitride synthesized from a gas phase. The present invention will be explained in detail below. In the present invention, a carbon base material that is inexpensive and does not cause high temperature creep is used as the base material of the setter. Then, CVD (Chemical Vapor Deposition; Che
Aluminum nitride (AIN) synthesized from the gas phase using the ++1cal Vapor Deposition method
Or by coating with boron nitride (BN),
A setter for firing aluminum nitride ceramics can be obtained. The raw materials for the CVD method when coating aluminum nitride include aluminum halides such as AlC1, ANBr3, and organic metals such as (CH3)3A1 () ethylaluminum) as the Al source, and mainly 4 as the N source. NH3, respectively. When producing and coating aluminum nitride on the surface of a carbon substrate using the CVD method, the reaction temperature is preferably 800°C or higher; at temperatures below this, the crystallinity of aluminum nitride decreases and it becomes resistant to moisture and oxygen. There is a risk of stability. In addition, as raw materials for the CVD method when coating boron nitride, boron halides such as BC aluminum and diborane (B
2H6) etc., and NH, can be mainly used as the N source. When producing and coating boron nitride on the surface of a carbon substrate using the CVD method, the reaction temperature is 180℃.
The temperature is preferably 0° C. or higher; if the temperature is lower than this, there is a risk that boron nitride, which has a low crystallinity and is unstable to moisture and oxygen, may be produced. When creating a setter by coating the surface of the carbon base material with aluminum nitride or boron nitride as described above,
When firing the aluminum nitride ceramics, it is desirable to cover the entire surface of the carbon base material with aluminum nitride or boron nitride, not just the surface that comes into contact with the aluminum nitride ceramics. If part of the surface of the carbon base material is not covered with aluminum nitride or boron nitride and is exposed,
This may cause early deterioration of the setter due to oxidation during firing of the aluminum nitride ceramics or diffusion of carbon into the aluminum nitride ceramics through the gas phase.

[Effect]

The aluminum nitride firing setter obtained as described above uses an inexpensive carbon base material as a base material, and the aluminum nitride and boron nitride coated on the surface of the carbon base material are formed in a thin film, so it is inexpensive. can be created. This carbon base material hardly causes high-temperature creep, so the life of the setter that can be repeatedly used for firing aluminum nitride ceramics can be extended, and the aluminum nitride and boron nitride coating the carbon base material can be used at high temperatures. Since it is stable, there is no fear that the setter will adhere to or oxidize the aluminum nitride ceramics when the aluminum nitride ceramics are fired. Moreover, since the aluminum nitride and boron nitride coated on the surface of the carbon base material are formed by synthesis from the gas phase, they can be obtained as extremely pure products that do not contain sintering aids. There is no fear that impurities will be diffused into the aluminum nitride ceramics when the aluminum nitride ceramics are fired, and it is possible to prevent uneven firing or warping of the aluminum nitride ceramics substrate.

【Example】

Next, the present invention will be explained by examples. K1 property 1 Add A1 to the AI source as a raw material. C13, NH3,f as N source
An aluminum nitride film was coated on the surface of a carbon base material processed into the shape of a setter by a low-pressure thermal CVD method using a vacuum cleaner. A IC1, was obtained by heating a container containing metal AI to 250° C., introducing HC1tj gas and H2 gas as a carrier gas, and causing a reaction. In addition, in the reaction by CVD method, the reaction temperature is 1000°01 and the pressure inside the reaction tube is IT.
The reaction time was 17 hours. The thickness of the aluminum nitride film of the setter obtained in this way was measured by SEM of the cross section of the film.
It was measured by observation (electron microscopy), and the impurity concentration of the aluminum nitride film was measured by ICP emission spectrometry. As a result, the thickness of the aluminum nitride film was 50
μm, and the amount of metal impurities was 10 ppm or less. A setter was obtained by coating the surface of a carbon substrate with an aluminum nitride film in the same manner as in Example 1, except that the reaction time of the CVD method was set to 2 hours. The thickness of the aluminum nitride film of this setter was 100 μm, and the amount of metal impurities was 10 ppm or less. "Dog" and "Medicine" - As raw materials, BCl23N gas is used as the B source, NH3 gas is used as the N source, and H2 gas is used as the carrier for each of the carbon groups processed into the shape of a setter by the low pressure thermal CVD method. The surface of the material was coated with a boron nitride film. In the reaction by CVD method, the reaction temperature is 8-1900℃, the pressure inside the reaction tube is ITorr, and the reaction time is 2.
This was done under time constraints. The thickness of the boron nitride coating on the setter thus obtained was 1.08 m, and the amount of metal impurities was 10 ppm or less. A setter was obtained by coating the surface of the carbon substrate with a boron nitride film in the same manner as in Example 3, except that the reaction time of the CVD method was set to 0.5 hours. The thickness of the boron nitride coating on the setter was 30 μm, and the amount of metal impurities was 10 ppm or less. Using each coated setter, aluminum nitride ceramic substrates were fired.As a result, none of the setters reacted with the aluminum nitride ceramic substrate to cause any adhesion, and there was no uneven burning, warping, or impurities on the aluminum nitride ceramic substrate. No contamination or oxidation was observed.Also, even when each center was used repeatedly for firing aluminum nitride ceramics 30 times, the setter warped due to high-temperature creep, and the aluminum nitride coating and boron nitride coating did not peel or crack. [Effects of the Invention] As mentioned above, the setter according to the present invention coats the carbon base layer with aluminum nitride or boron nitride synthesized from the gas phase, and uses inexpensive carbon. The base material is the base material,
Moreover, since the aluminum nitride and boron nitride coated on the surface of the carbon base material are formed in the form of a thin film, they can be produced at low cost, and since this carbon base material hardly causes high temperature creep, It is possible to extend the life of repeated use in firing aluminum nitride ceramics. Furthermore, since the aluminum nitride and boron nitride that coat the carbon base material are stable at high temperatures, there is no fear that setters will adhere to or oxidize the aluminum nitride ceramics when the aluminum nitride ceramics are fired. Since aluminum and boron nitride are synthesized from the gas phase, they are obtained as extremely high purity products that do not contain sintering aids, and when aluminum nitride ceramics are fired, aluminum nitride ceramics There is no fear that impurities will be diffused into the aluminum nitride ceramic substrate, and uneven heating or warping can be prevented from occurring in the aluminum nitride ceramic substrate.

Claims (2)

[Claims] (1) A setter for firing aluminum nitride ceramics, characterized in that a carbon base material is coated with aluminum nitride synthesized from a gas phase. (2) A setter for firing aluminum nitride ceramics, characterized in that a carbon base material is coated with boron nitride synthesized from a gas phase.