JPS61201669A - Aluminum nitride sintered body and manufacture - 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 an aluminum nitride sintered body and a method for manufacturing the same, and more specifically, it relates to a sintered aluminum nitride body and a method for manufacturing the same, and more specifically, it has practical properties such as denseness, thermal conductivity, insulation, and dielectric constant. The present invention relates to an aluminum nitride sintered body having excellent properties and a method for producing the same.

BACKGROUND OF THE INVENTION Aluminum nitride (AIN) sintered bodies are attracting attention as insulating materials or packaging materials in the semiconductor industry due to their high thermal conductivity and high insulation properties.

By the way, when producing a sintered body using AIN alone, AIN
Since the sinterability of AIN itself is not good, the relative density of the AIN sintered body obtained by molding and sintering AIN powder (based on the theoretical density of AIN, 3.26 g/cat) depends on the sintering conditions. It depends on the situation, but it shows only 70-80% at most. For this reason, pressure sintering using a hot press has also been attempted, but good results have not been obtained.

In general, in insulating ceramics such as aluminum nitride sintered bodies that mainly conduct phonons, phonon scattering occurs due to defects such as pores and impurities, reducing thermal conductivity.

On the other hand, recent advances in LSI have been remarkable, and the degree of integration has been significantly improved. The increase in IC chip size also contributes to this, and as the IC chip size increases, the amount of heat generated per package increases.

For this reason, importance has been placed on the heat dissipation properties of substrate materials. Further, the thermal conductivity of alumina sintered bodies conventionally used as IC substrates is insufficient in heat dissipation, and it is becoming impossible to cope with the increase in the amount of heat generated by IC chips. Therefore, as a substitute for the alumina substrate, a highly thermally conductive ceramic substrate is used, but it has the drawback of being highly toxic and difficult to handle.

From the above-mentioned technical background, it is desired that aluminum nitride sintered bodies having high insulation properties have higher thermal conductivity, that is, higher density.

Problems to be Solved by the Invention An object of the present invention is to provide a dense aluminum nitride sintered body having high thermal conductivity and a method for manufacturing the same.

More specifically, it is an object of the present invention to provide a sintered aluminum nitride body that can be suitably used as an insulating material or a packaging material for semiconductors, and a method for manufacturing the same.

Means for Solving the Problems In view of the problems of the prior art described above, the present inventors conducted various studies on aluminum nitride sintered bodies, and as a result,
Periodic table I such as Y, Sc, La, Ce, Sm
[[Nitride of group a series elements improves the sinterability of aluminum nitride and is effective in realizing a dense sintered body,
It has also been found that the method is effective in improving the thermal conductivity of the sintered body.

That is, according to the present invention, at least one type of powder selected from nitrides of elements of group MA of the periodic table is
A dense aluminum nitride sintered body with excellent thermal conductivity is provided, which is characterized by being sintered from a mixed powder of aluminum nitride containing 5Qwt%.

Furthermore, according to the present invention, at least one kind of powder selected from nitrides of elements in the Ma group of the periodic table, such as Y, Sc, La, Ce:, Sm, etc.
A method for producing an aluminum nitride sintered body is provided, which comprises molding a mixed powder of aluminum nitride containing ~5Qwj% and then sintering it at a temperature of 1500 to 2200°C in a non-oxidizing atmosphere.

The non-oxidizing atmosphere is one or more atmospheres selected from the group consisting of vacuum, nitrogen gas, hydrogen gas, carbon monoxide gas, argon gas, and helium gas.

Further, according to a preferred embodiment of the present invention, the molded mixed powder described above is pressure sintered using a hot press at a pressing pressure of 20 kg/cnf or more in a non-oxidizing atmosphere.

The aluminum nitride sintered body produced according to the present invention has a
% or more, and the thermal conductivity at room temperature is 8.
This is more than 0 W/m-.

Furthermore, the aluminum nitride sintered body according to the present invention contains 0.1 to 5 Qwt% of at least one kind of powder of nitride of group IIIa series elements of the periodic table, and also contains powders of I[oxides of group Ia series elements, fluorides, Furthermore, Ila group subseries elemental compounds,
It may also contain oxides and fluorides.

Effect of the Invention Next, the reason for limiting the range of components of the aluminum nitride sintered body of the present invention and the reason for limiting the conditions of the manufacturing method will be explained.

The mixing ratio of nitrides of group IIIa series elements of the periodic table is
The reason why the range is 0.1 to 50 wt% is that if it is less than 0.1 wt%, there will be no addition effect and a sufficiently dense sintered body will not be obtained, and if it exceeds 50 wt%, the resulting sintered body will have a This is because conductivity tends to decrease.

The sintering temperature is 1500 to 2200°C.
This is because sintering is not performed sufficiently at temperatures below .degree.

Regarding sintering of aluminum nitride, it is desirable that the sintering temperature be high, but if the temperature is 2200° C. or higher, the decomposition reaction of aluminum nitride will be significantly accelerated, resulting in a large weight loss of the sintered body.

For example, the mechanism by which the sinterability of aluminum nitride is improved by the addition of nitrides of Group IIIa elements of the periodic table, such as Y, La, S5Sm, and Ce, is not clear;
It is thought that the nitride of the Ma group elements of the periodic table promotes solid phase sintering of aluminum nitride.

Furthermore, as shown in the Examples below, the thermal conductivity increased by a maximum of more than four times compared to the sintered body of aluminum nitride without additives. This is thought to be because the densification of the aluminum nitride sintered body is promoted, but the details of the mechanism by which the thermal conductivity improves are not clear.

EXAMPLES The present invention will be explained below with reference to Examples, but it goes without saying that these Examples do not limit the scope of the present invention in any way.

Example 1 Yttrium nitride powder (particle size of 0.5 m or less) was added to aluminum nitride powder (particle size of 1 to 3 μm) from 0.1 to 0.1 μm.
The mixed powder added at varying mixing ratios within the range of 50 wt% was preformed with a press pressure of 2 tOn/Cd, and
Sintering was performed at various temperatures ranging from 0 to 2200°C for 3 hours.

The density (relative density based on 3.26 g/cnf) of the obtained sintered body is shown in FIG.

The sintering was carried out in an atmosphere of N2 gas (1, atm). Also,
The yttrium nitride powder was mixed for 12 hours using a ball mill (manufactured by AIN).

In Figure 1, the . mark indicates a sintering temperature of 2200°C, the ■ mark indicates a sintering temperature of 2000°C, the circle with the right half filled in black indicates a sintering temperature of 1800°C, and the mark mark indicates a sintering temperature of 1600°C. , ■ indicate the relative density of the aluminum nitride sintered bodies sintered at a sintering temperature of 1400° C., which is outside the range of the present invention.

As shown in FIG. 1, it contains IJium nitride in an amount within the range of the present invention, that is, 0.1 to 50-t%,
It is confirmed that the aluminum nitride sintered body sintered at a temperature of 1500° C. or higher has a high density.

Example 2 An aluminum nitride-yttrium nitride mixed powder having the composition shown in Example 1 was hot pressed (pressing pressure 200 kg).
Figure 2 shows the density of the sintered body obtained when pressure sintering was performed for 2 hours using the sintered body (/cJ).

In Fig. 2, the . mark indicates a sintering temperature of 2200°C, the O mark indicates a sintering temperature of 2000°C, the black circle on the right half indicates a sintering temperature of 1800°C, and the square mark indicates a sintering temperature of 1600°C. , ■ indicate the relative density of the aluminum nitride sintered bodies sintered at a sintering temperature of 1400° C., which is outside the range of the present invention.

From the results shown in Figure 2, it was confirmed that the aluminum nitride sintered body containing 0.1 to 50 wt% yttrium nitride and sintered at a temperature of 1500°C or higher has a high density, and at the same time, It can be seen that pressure sintering can produce a sintered body with high density and stable characteristics.

Example 3 Among the sintering conditions shown in Example 2, a sintered body was pressure sintered under the case where the yttrium nitride content was 115 wt% and when the press pressure of the hot press was 20 kg/c111. The density of the aluminum nitride sintered body is shown in Table 1. From the results of this example, even when pressure sintered by hot pressing, the aluminum nitride sintered body has a density of 90% or more at a sintering temperature of 1500°C or higher, which is within the range of the present invention. I know that it will happen.

Example 4 A mixed powder in which lanthanum nitride powder was added to aluminum nitride powder (particle size 1 to 3 μm) was mixed for 12 hours using a ball mill (manufactured by AIN).

Table 2 shows the density and thermal conductivity of the sintered body.

Example 5 For yttrium nitride, cerium nitride, and scandium nitride, changes in thermal conductivity depending on the amount added are shown in FIG. 3 when the sintering temperature is 2000°C.

The sintering time for pressure sintering using a hot press (press pressure 200 kg/ctd) of the mixed powder containing IJ nitride was 2 hours, and the other sintering times were 3 hours. Further, the method for preparing the mixed powder and the sintering method were in accordance with Example 1 and Example 2.

In Fig. 3, the ○ mark contains yttrium nitride and the sintering temperature is 2000°C, the * mark contains yttrium nitride and pressure sintering at 2000°C in a hot press, and the mu mark Contains scandium nitride, sintering temperature of 2000 ° C,
The symbol ■ indicates the thermal conductivity of aluminum nitride sintered bodies containing cerium nitride and sintered at a sintering temperature of 2000°C. For comparison, the thermal conductivity of sintered powder of AIN alone is shown as a comparative example.

As is clear from the results shown in Figure 3, the addition of yttrium nitride, scandium nitride, and cerium nitride accelerates the sintering of aluminum nitride, resulting in a sintered body with high density and excellent thermal conductivity. Recognize. It is also found that when the content of various additives is 30% or less, a sintered body having particularly excellent thermal conductivity can be obtained.

Example 6 Aluminum nitride powder (particle size 1 to 3μ), yttrium nitride powder, yttrium oxide, yttrium fluoride,
A mixed powder containing at least one powder selected from calcium oxide, calcium nitride, and calcium fluoride is preformed at a press pressure of 2 tons/Cll1,
Pressureless sintering was performed at 1800°C for 3 hours. Density of the obtained sinter (relative density based on 3,26 g / c♂)
are shown in Table-3.

Sintering was performed in an atmosphere of N2 gas (1.0 atm).

Table 3 Effects of the Invention As explained above, the present invention provides powders of at least one type selected from nitrides of elements of group MA of the periodic table.
Molding a mixed powder of aluminum nitride containing 50 wt%,
The aluminum nitride sintered body obtained by the present invention is then sintered at a temperature of 1500 to 2200°C in a non-oxidizing atmosphere. It has excellent dielectric properties and is useful as an insulating material for semiconductors or a package material.

The aluminum nitride sintered body of the present invention can be used as an I
As a heat sink for not only C substrates but also power transistors, power diodes, and laser diodes.
Furthermore, it can be suitably used as a laser disk or as an insulating thin plate as an alternative to mica.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between the mixing ratio of aluminum nitride powder and the density of the obtained sintered body of the aluminum nitride sintered body manufactured in Example 1 of the present application. , is a graph showing the relationship between the mixing ratio of yttrium nitride powder in the aluminum nitride sintered body produced in Example 2 of the present application and the density of the obtained sintered body, and FIG. It is a graph showing the relationship between the mixing ratio of yttrium nitride, cerium nitride, and scandium nitride in the produced aluminum nitride sintered body and the thermal conductivity of the obtained sintered body.

Claims (4)

[Claims] (1) Dense and thermally conductive, characterized by being sintered from a mixed powder of aluminum nitride containing 0.1 to 50 wt% of at least one type of powder selected from nitrides of group IIIa elements in the periodic table. Aluminum nitride sintered body with excellent properties. (2) A mixed powder of aluminum nitride containing 0.1 to 50 wt% of at least one type of powder selected from nitrides of Group IIIa elements of the periodic table is molded, and then 1500 to 2
A method for producing an aluminum nitride sintered body, comprising sintering at a temperature of 200°C in a non-oxidizing atmosphere. (3) The non-oxidizing atmosphere is one or more atmospheres selected from the group consisting of vacuum, nitrogen gas, hydrogen gas, carbon monoxide gas, argon gas, and helium gas. A method for producing an aluminum nitride sintered body according to claim 2. (4) The above molded mixed powder was placed in a non-oxidizing atmosphere for 2 hours.
The method for producing an aluminum nitride sintered body according to claim 2 or 3, characterized in that pressure sintering is performed using a hot press at a press pressure of 0 kg/cm^2 or more.