JPS61261270A - 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 producing an aluminum nitride sintered body. (Prior art and its problems) In recent years, due to rapid technological innovation in the semiconductor industry, fi, IC.

Large-scale integrated circuits such as L8I are highly integrated.

As power output has been increased, the amount of heat generated per unit area of silicon devices 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.

Traditionally, alumina sintered bodies have been the most commonly used insulating substrate material, but recently, alumina substrates have not been 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).
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 about 4.3X10/℃ (average value from room temperature to 400℃), which is about 7X1 of alumina sintered body.
It is smaller than 0=/℃, and the thermal expansion coefficient of the silicon element is 3.
5-4. OX 10''/l?: Close to 0, and the mechanical strength is approximately 50/9/mm2 in terms of bending strength.

It is a material with high strength and excellent electrical insulation properties compared to the value of 20 to 30 Kg/mm2 for alumina sintered bodies.

Conventionally, aluminum nitride (A/N) sintered bodies are obtained by molding and sintering aluminum nitride powder.
Since aluminum nitride is a difficult-to-sinter substance, it is difficult to obtain a dense sintered body.

Up to now, attempts have been made to obtain dense aluminum nitride sintered bodies by adding sintering aids and using pressureless sintering or hot pressing.
2O3 shows a method for producing an aluminum nitride sintered body in which yttrium oxide (ytO,) is added as a sintering agent. According to this method, the thermal conductivity is 100 W/mk.
(room temperature) aluminum nitride sintered body was obtained.

However, with the recent development of integrated circuit technology, there is a demand for heat dissipating substrate materials with even higher thermal conductivity.As a result of intensive research to address the above-mentioned situation, we have found that alkaline earth metal Calcium carbide (CaC2), strontium carbide (8rC1), which are acetylide compounds
By using a combination of one or more types of barium carbide (Bad, ) and yttrium oxide (YtOs) in appropriate amounts, a thermal conductivity at room temperature of 120 W/mk or higher, which is higher than that of conventional aluminum nitride sintered bodies, can be obtained. Based on this knowledge, 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 produced by molding a mixed powder in which aluminum nitride powder is blended with one or more types of alkaline earth metal acetylide compounds and yttrium oxide as additives.

A method for manufacturing an aluminum nitride sintered body characterized by firing in a non-oxidizing atmosphere (Detailed description of structure) The present invention will be specifically described below.

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

In the present invention, the additives include at least one acetylide compound of an alkaline earth metal, Y, 0. It is necessary to add both. That is, by using a suitable amount of alkaline earth metal acetylide compound in combination with Y, O,
Fi conductivity can be significantly increased ◎ Especially when the total amount of alkaline earth metal acetylide compounds is 0.02 to 1
By setting 0 weight - and Y and 0° to a predominant amount of 0.1-1 On, a thermal conductivity of 120 W/mk (room temperature) or more can be obtained, which is larger than that of conventional aluminum nitride sintered bodies. Acetylide compounds react actively with oxygen, moisture, etc.1), and some of them are explosive, so use a non-aqueous solvent such as alcohol for mixing, and use a non-oxidizing atmosphere such as nitrogen gas for heating and drying. In addition, the acetylide compound is preferably CaC2g 8rC@@BaC2, which requires caution in the powder processing step, such as not maintaining the powder at a high temperature.

Next, sintering requires high temperature sintering in a non-oxidizing atmosphere. If sintered in an oxidizing atmosphere, aluminum nitride will oxidize and a dense sintered body cannot be obtained. ◎Kiln gas is used as a non-oxidizing atmosphere.

Helium gas, argon gas, -carbon oxide gas.

Hydrogen gas, vacuum atmosphere, etc. can be used, and among them, kiln gas, argon gas, helium gas, and vacuum atmosphere are convenient and preferable. Sintering is performed at a temperature of 1500 to 2000°C, and 1600 to 1900°C is particularly effective, but the temperature range is not particularly limited. Also, sintering can be done by normal pressure sintering method or pressure sintering method ◎ Pressure sintering methods include hot press method (-axis pressure sintering method) and HIP method.
Either method (hot isostatic pressing sintering method) is possible◎
In particular, when sintered by the hot press method, a highly thermally conductive sintered aluminum sintered body can be obtained〇The present invention will be specifically explained with reference to Examples 0 (Example 1) Aluminum nitride with an average particle size of 2 μm Various additives shown in Table 1 were added to the powder, and then the mixed powder was heated at room temperature.
A pressure of 000 h/es2 was applied to form a molded body. Table 1 shows the relative density and thermal conductivity at room temperature of the sintered aluminum sintered body obtained by sintering this compact at room temperature at 1800° C. for 2 hours in a nitrogen gas atmosphere in a sintering furnace. By the manufacturing method of the present invention, a highly thermally conductive sintered aluminum body having a thermal conductivity of 120 W/mK or more at room temperature was obtained.

The following margin (Example 2) Various additives shown in Table 2 were added to the silica aluminum powder having an average particle size of 2 μm, and then the mixed powder was mixed with 2 μm at room temperature.
A pressure of 000 Kg/cxa2 was applied to form a molded body.

This molded body was sintered in a sintering furnace in a kiln gas atmosphere under the conditions shown in Table 2.The relative density and thermal conductivity at room temperature of the sintered aluminum body are shown in Table 2.Production of the present invention By this method, a highly thermally conductive aluminum nitride S + cum sintered body with a thermal conductivity of 120 W/mk or more at room temperature was obtained.

(Example 3) 2% by weight of calcium carbide (CaC,) and yttrium oxide (Y, O,) were added to aluminum nitride powder with an average particle size of 0.6 μm and a purity of 99% (total of metal impurities of 300 ppm or less). After mixing in xylene, the filtered powder was heated and dried in a vacuum.Then, this mixed powder was applied a pressure of 2000K97cm2 at room temperature to form a molded body. This molded body was placed in a hot press mold made of graphite, and heated to 400°C at 1800°C for 2 hours in a 97cm2 nitrogen atmosphere.
An aluminum nitride sintered body was obtained by hot pressing for hours.

This aluminum nitride sintered body has a relative density log' at room temperature.
s, 7% conduction wheel 180W/mk, thermal expansion coefficient 4.3×10
-6/'C, specific resistance 4X10"Ωm9 bending strength 60Kt
/mm2, and also has translucency, and the transmittance for wavelengths of 4 to 6 μm, for example, is 0.2 μm.
It is about 45% for a 5 mm sample, and 0, 2 to 6
．． It showed a transmittance of 10% or more at a wavelength in the 5 μm range.

(Effects of the invention) The aluminum nitride sintered body produced by the production method of the present invention had high density, excellent conductivity, and good thermal properties, electrical properties, mechanical properties, and optical properties. In addition to its application 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 components.It is also a window material that utilizes optical properties such as translucency. It is also possible to apply it as an optical material.

It has many industrial advantages.

Claims (2)

[Claims] (1) An aluminum nitride sintered body is produced by molding a mixed powder of aluminum nitride powder with one or more alkaline earth metal acetylide compounds and yttrium oxide as additives, and then firing it in a non-oxidizing atmosphere. Production 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.