JPS61270264A - Manufacture of aluminum nitride sintered body - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method for manufacturing an aluminum nitride sintered body.

(Prior art and its problems) In recent years, due to rapid technological innovation in the semiconductor industry, IC, LS
Large-scale integrated circuits such as I have become highly integrated and have high output, and as a result, the amount of heat generated per unit area of silicon elements has increased significantly.

Therefore, a problem has begun to arise that disturbs the normal operation of the silicon element due to heat generated by the energizing operation of the silicon element. Accordingly, insulating substrate materials with good thermal conductivity are required.

Conventionally, alumina sintered bodies have been most commonly used as insulating substrate materials. However, recently, alumina substrates cannot be said to be satisfactory in terms of heat dissipation.
Furthermore, there has been a demand for the development of insulating substrate materials with excellent heat dissipation (thermal conductivity). As such an insulating substrate material, it has good thermal conductivity (high thermal conductivity).
It is required to have properties such as electrical insulation, a coefficient of thermal expansion close to that of silicon single crystal, and high mechanical strength.

By the way, aluminum nitride, which is known to have good thermal conductivity, has a coefficient of thermal expansion of approximately 4.3X 104/C (
(average value from room temperature to 400℃) of the alumina sintered body.
X 10-'/l, and the thermal expansion coefficient of the silicon element is 3.5-4. Close to OX 10-'/l. It also has a mechanical strength of about 50 to 9/- in terms of bending strength, which is higher than that of alumina sintered body, which is 20 to 30 kg/-, and is a material with excellent electrical insulation properties.

Conventionally, aluminum nitride (CAIN) sintered bodies are obtained by molding and sintering aluminum nitride powder, but since aluminum nitride is a difficult-to-sinter substance, it is difficult to obtain dense sintered bodies. be.

Up to now, attempts have been made to obtain a dense aluminum nitride sintered body by adding a sintering aid and using an atmospheric sintering method or a hot pressing method. P of the Proceedings of the 1981 Ceramics Association Annual Meeting
A method for producing an aluminum nitride sintered body is disclosed in which 2O3 (IJOI) is added as a sintering aid. According to this method, the thermal conductivity is 100w/m
k (room temperature) aluminum nitride sintered body was obtained.

However, with the recent development of integrated circuit technology, there is a demand for heat dissipation substrate materials having even higher thermal conductivity.

The present inventor has attempted to address the above-mentioned situation.As a result of extensive research, the present inventors have found that calcium carbide (CaC,), strontium carbide (SrC,
), by using a combination of one or more types of barium carbide (Back) and calcium oxide (Cab) in appropriate amounts, the thermal conductivity at room temperature is 120 w/mk or more, which is higher than the conventional aluminum nitride sintered body. Based on this finding, we have completed the present invention.

(Objective of the Invention) An object of the present invention is to provide a method for producing an aluminum nitride sintered body having high thermal conductivity and various useful properties.

(Structure of the Invention) The present invention is a nitriding process characterized in that a mixed powder of aluminum nitride powder mixed with at least one kind of alkaline earth metal acetylide compound and calcium oxide as additives is molded and then fired in a non-oxidizing atmosphere. This is a method for manufacturing an aluminum sintered body.

(Detailed explanation of configuration) The present invention will be specifically explained below.

First, the aluminum nitride raw material has a high purity, for example, preferably 98% or more, but 95 to 98%
It is also possible to use a medium-sized one. The average particle size is preferably 10 pm or less, preferably 2 pm or less.

In the present invention, it is necessary to add at least one kind of alkaline earth metal acetylide compounds such as CthC, SrC, and BaC, and both CaO and CaO.

That is, alkaline earth metal acetylide compounds and Ca
By using an appropriate amount of O in combination, thermal conductivity can be significantly increased. In particular, by adjusting the total amount of alkaline earth metal 7 cetylide compounds to 0.02 to 10% by weight and CaO to 0.1 to 5% by weight, the thermal conductivity can be reduced to t2ow.
/mk (room temperature) or higher than conventional aluminum nitride sintered body)
A large value can be obtained. Acetylide compounds tend to react actively with oxygen, moisture, etc., and some of them are explosive, so use a non-aqueous solvent such as alcohol when mixing, and dry under heat in a non-oxidizing atmosphere such as nitrogen gas. Care must be taken in the powder processing process, such as not holding the powder at too high a temperature.

Next, sintering requires high temperature sintering in a non-oxidizing atmosphere. If sintered in an oxidizing atmosphere, aluminum nitride will be oxidized and a dense sintered body will not be obtained. As the non-oxidizing atmosphere, nitrogen gas, helium gas, argon gas, -carbon oxide gas, hydrogen gas, vacuum atmosphere, etc. can be used, and among them, nitrogen gas, argon gas, helium gas, and vacuum atmosphere are convenient and preferred. Sintering is 1500-2
000°C, and 1600 to 1900°C is particularly effective, but is not particularly limited to these temperature ranges.

Further, the sintering may be performed by a pressureless sintering method or a pressure sintering method. As the pressure sintering method, either the hot press method (-axis processing sintering method) or the HIP method (hot isostatic pressing sintering method) is possible. In particular, when sintered by hot pressing, a highly thermally conductive aluminum nitride sintered body can be obtained.

Next, the present invention will be specifically explained with reference to Examples.

(Example 1.) Various additives shown in Table 1 were added to aluminum nitride powder with an average particle size of 2 μm, and then this mixed powder was heated at room temperature for 2 μm.
A pressure of 000 #/c-j was applied to form a molded product. Table 1 shows the relative density and thermal conductivity at room temperature of the aluminum nitride sintered body obtained by sintering this compact in a sintering furnace at 1800° C. for 10 hours under normal pressure in a nitrogen gas atmosphere. By the production method of the present invention, a highly thermally conductive aluminum nitride powder with a thermal conductivity of 120 w/m k or more at room temperature (1" nail, 15 white (Example 2)) and an average particle size of 2 μm is produced. Add various additives shown in Table 2, and then mix the powder mixture at room temperature for 2 hours.
A pressure of 000 #/d was applied to form a molded body. Table 2 shows the relative density and thermal conductivity at room temperature of the aluminum nitride sintered body obtained by firing this compact in a sintering furnace in a nitrogen gas atmosphere under the conditions shown in Table 2. By the manufacturing method of the present invention, a highly thermally conductive aluminum nitride sintered body having a thermal conductivity of 120 W/mK or more at room temperature was obtained.

(Example 3.) 2% by weight of calcium carbide (CaC) and 1% by weight of calcium oxide (Cab) were added to aluminum nitride powder with an average particle size of 0.6 μm and a purity of 99g6 (total of metal impurities of 300 ppm or less). The powder, which was added and mixed in xylene and filtered, was heated and dried in vacuo.

Next, a pressure of 2,000 #j was applied to this mixed powder at room temperature to form a compact. This molded body was placed in a hot press mold made of graphite, and hot pressed at 1800°C at 400°C and 9Δ for 2 hours in a nitrogen atmosphere to obtain an aluminum nitride sintered body.

This aluminum nitride sintered body has a relative density of 1004 at room temperature.
Ji, thermal conductivity 180w/mk, thermal expansion coefficient 4.3X10
″4//℃, specific resistance 4×10″Ω11 bending strength 60 絨-
It exhibited the following characteristics and also had translucency. For example 4~
The transmittance for light with a wavelength of 6 μm is approximately 45% for a sample with a thickness of 0.5 ff, and the transmittance is 0.2 to 6.5 pW.
It exhibited a transmittance of 10g6 or more at wavelengths in the range of I.

(Effects of the invention) The aluminum nitride sintered body produced by the production method of the present invention had high density and excellent thermal conductivity, and had good thermal properties, electrical properties9 mechanical properties, and also good optical properties. In addition to being used as a heat dissipation material in the semiconductor industry, it can also be used as a high-temperature material for crucibles, vapor deposition containers, heat-resistant jigs, and other high-temperature materials.Furthermore, it can be used as a window material that utilizes optical properties such as translucency. It can also be used as an optical material, etc.
It has many industrial advantages.

``A to J+''! ! Sogo Uchihara , f

Claims (2)

[Claims] (1) Aluminum nitride sintered body characterized by molding a mixed powder of aluminum nitride powder, blending one or more alkaline earth metal acetylide compounds and calcium oxide as additives, and then firing it in a non-oxidizing atmosphere. manufacturing method. (2) The acetylide compound of alkaline earth metal is CaC_
2, SrC_2, BaC_2
A method for producing an aluminum nitride sintered body as described in 1.