JPH0283262A - Production of sintered material of aluminum nitride having metallized layer - Google Patents

Abstract

PURPOSE:To obtain a sintered material having high thermal conductivity by making a relative density of sintered material >= a specific value while controlling content of a sintering auxiliary comprising Y2O3 or Gd2O3 in sintered material and content of oxygen <= specific values. CONSTITUTION:AlN powder as a main component and <=0.65wt.% based on parent material of Y2O3 or Gd2O3 as a sintering auxiliary are processed to give a green sheet of pressed molded article or tape molded article. The green sheet is coated with a paste consisting of Al compound powder of additive, W powder, a binder and a solvent by screen printing and simultaneously calcined in a nonoxidizing atmosphere at 1,700-2,000 deg.C to give a sintered material having <=0.3wt.% O2 content and >=98% relative density. Sintered AlN containing a metallized layer having >=160W/m.K thermal conductivity is obtained by this method.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an aluminum nitride sintered body, which is attracting attention in many fields including IC insulating substrates, and particularly to a method for manufacturing an aluminum nitride sintered body having a metallized layer. .

[Prior Art] The degree of integration in recent ICs has improved markedly. Since the amount of heat generated increases with the increase in the degree of integration, the heat dissipation performance has become important.

Alumina has excellent electrical insulation properties and chemical and thermal stability, so it has been widely used as an IC insulating substrate material. Sexuality is becoming less satisfying. For this reason, beryllia, which has high thermal conductivity, is being considered as an IC substrate material, but beryllia has the drawbacks of being highly toxic and difficult to handle.

Aluminum nitride (AIN) has excellent thermal conductivity, electrical insulation, chemical and thermal stability, and is non-toxic.
It is attracting attention as an IC insulating substrate material that can replace alumina. In order to use an AIN sintered body as an ICC insulating substrate material, it is usually essential to form a metallized layer on its surface. The method for forming the metallized layer is the thick film firing method, DBC (Direct Bond Co.
pper) method, thin film method, etc., and many successful examples have been reported.

In addition, there are also successful examples of a simultaneous sintering method in which a paste made of a metallizing composition is applied to an AIN green body and fired in a non-oxidizing atmosphere, and several examples have been reported.

An example thereof is a composition and method for metallizing non-oxide ceramic bodies (Japanese Patent Publication No. 62-27037). This document discloses a composition that can obtain a strong grafting that is possible with plating and brazing, and a metallization method using the same.
A metallizing composition containing, in addition to W and Mo, a component material of non-oxide ceramics, that is, AIN, and a metal or a metal oxide;
A co-firing method is described in which the paste is applied to an IN green compact and fired in a non-oxidizing atmosphere.

There are some reports of other examples, but good AIN with high adhesion strength can be achieved by adding AIN to W or Mo paste, or by adding other metals or metal oxides.
It was determined that a sintered body could be obtained, and the mechanism of its adhesion was that the melt containing the sintering aid component leaked from the AtN sintered body side into the metallized layer by capillary action, solidified, and formed a metalized layer. It is thought that the AIN sintered body is firmly attached to the AIN sintered body due to its mechanical strength.

[Problems to be Solved by the Invention] Therefore, the present inventors measured the thermal conductivity of an AIN substrate provided with a metallized layer containing the same components as above, and found that it was 60 to 140 W/m. The value of k was unexpectedly low, and after intensive investigation, it was found that the cause was the extremely poor thermal conductivity of glass #H, which was formed by solidification of the melt containing the sintering aid component. I came to the conclusion that there is.

In other words, a few μ
A glass layer with a thickness of m is formed, and this serves as a barrier to phonon conduction, which is the main component of heat conduction in insulating ceramics. Therefore, even if an AIN sintered body having high thermal conductivity is used, the glass phase inhibits thermal conduction, and the excellent property of high thermal conductivity inherent to AIN cannot be fully exhibited.

The present invention aims to solve such problems in AIN sintered bodies.

[Means for Solving the Problems] The present invention provides that the content of a sintering aid made of yttrium oxide or gadolinium oxide in an aluminum nitride sintered body having a metallized layer of tungsten with an aluminum compound as an additive is 0.85% by weight or less for the material,
In addition, the content of oxygen contained in the sintered body is 0.3% by weight or less, the relative density is 98% or more, and the thermal conductivity is teow.
lm.

Le'M with a metallized layer densified to be more than K
A green sheet containing aluminum oxide sintered body and aluminum nitride powder as the main components, and a green sheet obtained by press molding or tape molding using yttrium oxide or gadolinium oxide as a sintering aid, and an aluminum compound mainly containing tungsten. A metallized paste having additives of This is a method for manufacturing a sintered aluminum nitride lamb having a metallized layer that densifies the material.

AI with metallized layer with high thermal conductivity by co-firing method
In order to obtain a N sintered body, it is necessary to reduce the thickness of the glass phase, which is a barrier to thermal conductivity, as much as possible, and to make the AIN sintered body and metallized layer denser, which are unavoidable in the AIN sintered body. It is important that the oxygen content is low.

In order to reduce the thickness of the glass layer as much as possible, it is most effective to suppress seepage of the melt containing the sintering aid component from the AIN sintered body side. The addition rate of the auxiliary agent was set to an extremely low level of 0.65fffffi% or less. Under these conditions, it is necessary to make the sintered body denser and to reduce the content of oxygen contained in the sintered body. For this purpose, there are methods of adding compounds selected from the na and ma groups of the periodic table as sintering aids and deoxidizing agents, such as CaO1Y203, and deoxidizing by adding carbon together with AIN powder and sintering. A method for obtaining a low-oxygen sintered body, a method for adding high-purity low-oxygen AIN powder, a method for decomposing and evaporating the sintering aid remaining in the AIN sintered body, and obtaining high-purity AIN sintered body. A method in which the sintering aid remaining in the sintered body is removed by exposing it to a reducing atmosphere for a long time, and the aid penetrates into the metallized layer from the AIN substrate, that is, the base material, and is used as a sintering aid and deoxidizer for the AIN powder. There are methods that achieve this effect, and there is no difference in the effect of any of these methods.

Regarding the densification of the metallized layer, although the details of the sintering mechanism of high-melting point metals are not clear in many parts, self-sintering properties are poor in a non-oxidizing atmosphere, but in an AtN sintered body, It has been revealed that when firing is performed by controlling the seepage of the melt containing the sintering aid component, the sinterability of the metallized layer is significantly improved and a dense metallized layer can be obtained. .

In addition, the required characteristics of the IC heat dissipation board material include warpage of 6.
It has a tensile strength of 0 μm or less and a tensile strength of 2°Okg/mm’ or more. If the warp exceeds 60 μm, the thermal resistance of the substrate increases rapidly, causing problems such as poor heat dissipation.

If the tensile strength is less than 2.0 kg/■', the substrate and the metallized layer will peel off due to thermal cycles during the IC manufacturing process. Normally, a glass layer formed from a melt containing a sintering aid component contained in the AtN sintered body contributes to improving the tensile strength, but the glass layer becomes a large barrier to heat conduction.

Therefore, in the present invention, the seepage of the melt is controlled, the glass layer is minimized, and an additive is used in the tungsten metallized layer to improve the wettability of the metallized layer, thereby improving the tensile strength. I'm trying.

To explain the present invention in detail, the additive aluminum compound used in the tungsten metallized layer is preferably AIN powder, aluminum oxide (A120), or aluminum oxynitride (AION). These are used as a paste by adding a binder consisting of tungsten powder, a known binder such as ethyl cellulose, acrylic resin, or polyvinyl alcohol, and a known solvent such as α-terpineol or butycarbinol.

In addition, as raw materials for the AIN sintered body, AIN powder and AI
Since N is difficult to sinter, an additive aid is used. As a sintering aid component, it decomposes during firing to produce yttrium oxide (
Using organic acid salts or alkoxides such as stearate of YlGd that produce Y2O2) or gadolinium oxide (Gd203), Y20y or Gd
It was used so that the amount was 0465% by weight or less based on the base material in terms of z03. From this, a green sheet is obtained by a press molding method and a tape molding method.

The above-mentioned paste is applied to this press-formed body or green sheet by screen printing and fired at 1700 to 2000°C in a non-oxidizing atmosphere to obtain an AIN sintered body having a metallized layer.

As described above, in order to control the formation of the glass phase, the relative density of the aluminum nitride sintered body having the metallized layer was made denser to 98% or more while suppressing the amount of gold platinum in the sintering aid.
By suppressing the content of oxygen that is inevitably included in the tN sintered body, the thermal conductivity of the AIN sintered body with the metallized layer can be increased to 180 W/m. It can be more than k.

[Example] As a sintering aid, an organic acid salt or alkoxide of Y or Gd is used as Y2O2 or cd20. Al2O3, A
After printing a predetermined pattern by screen printing a paste of W containing IN or AlON in various proportions,
Firing was carried out in a nitrogen atmosphere at 1,700 to 2,000"C for 1 to 5 hours. Table 1 shows the conditions for each example.

Table 1 Table 1 shows the density and oxygen content of the sintered body obtained in the above example, and also includes the thermal conductivity and warp Δp measured by the laser flash method. Shown in Table 2.

Further, after the surface was plated with Ni and soldered with a pb-Sn plated annealed copper wire, a tensile test was conducted. The results are also shown in Table 2.

Thermal conductivity is particularly excellent when the sintering temperature is 1800° C. or higher, and in any case, the warpage and tensile strength are less than 60 μm and 2 kg/2 or more, respectively, and there are no practical problems at all.

Table 2 Table 3 Table 4 [Comparative Examples] The conditions of each comparative example are shown in Table 3, and the test results of the sintered bodies obtained in each example are shown in Table 4.

Table 4 continued As is clear from the results shown above, the sintering temperature was 15
In the case of 00 to 1650°C, the relative density remains at 70 to 95%, and the thermal conductivity is 110 to 140 ν/m. It was as low as k. This is because any one of the amount of sintering aid added, oxygen content, and relative density is outside the scope of the present invention.

[Effects of the invention] The AIN sintered body according to the invention has excellent thermal conductivity and tensile strength, and has little warpage, so it is used as a substrate material or packaging material in the semiconductor industry, especially as a multilayer wiring board material that requires heat dissipation properties. Extremely effective.

Claims (3)

[Claims] (1) The content of the sintering aid made of yttrium oxide or gadolinium oxide in the aluminum nitride sintered body having a tungsten metallized layer containing an aluminum compound as an additive is 0.65% by weight or less based on the base material. And also,
The content of oxygen contained in the sintered body is 0.3% by weight or less, the relative density is 98% or more, and the thermal conductivity is 160W/m
．． An aluminum nitride sintered body having a metallized layer having a metallization layer of k or more. (2) A green sheet made of aluminum nitride powder as a main component and obtained by press molding or tape molding using yttrium oxide or gadolinium oxide as a sintering aid, and an additive of an aluminum compound mainly containing tungsten. 1700-2 in a non-oxidizing atmosphere.
Co-firing at 000℃, the thermal conductivity is 160W/m.
A method for producing an aluminum nitride sintered body having a metallized layer, the method comprising obtaining a sintered body having a metallization layer of k or more. (3) A metallized layer according to claim (2), wherein the metallized layer is densified by controlling seepage of a melt containing a sintering aid component contained in the aluminum nitride sintered body. A method for producing an aluminum nitride sintered body.