JPH08731B2 - High thermal conductivity aluminum nitride sintered body - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high heat conductive aluminum nitride sintered body used for an insulating substrate, a heat sink, etc., and more particularly to a high heat conductive aluminum nitride sintered body which can be easily metallized.

[0002]

2. Description of the Related Art In recent years, demands for miniaturization and functional improvement of electronic devices have become extremely large, and accordingly, semiconductors are required to have higher integration density, higher functionality, higher speed, higher output, and higher reliability. Is making rapid progress. Corresponding to these, the amount of heat generated from the semiconductor is increasing more and more, and a substrate having a large heat dissipation ability in place of the conventional Al ₂ O ₃ substrate is required. As a substrate material having a large heat dissipation capability, that is, a material having a high thermal conductivity, diamond,
Cubic BN (boron nitride), SiC (silicon carbide), BeO
(Beryllia), AlN (aluminum nitride), Si, etc. can be mentioned. However, diamond, cubic B
N is difficult to manufacture in a size that can be used as a substrate, and is very expensive. SiC is electrically insulating for a semiconductor, electrical properties such as dielectric constant inferior Al ₂ O _3, can not be used as a place of the Al ₂ O ₃ substrate.
BeO has excellent electrical characteristics, but powder produced during molding and grinding is toxic, so it cannot be manufactured domestically and may be unstable because it needs to be obtained from overseas. There is. Since Si has poor electrical characteristics and low mechanical strength, its use as a substrate material is limited.
AlN has excellent electrical properties such as high insulation, high withstand voltage, and low dielectric constant, and atmospheric pressure sintering can be applied. However, a metal layer cannot be formed on the required surface, so that a multilayer substrate for high output is still available. The reality is that it has not been developed.

[0003]

As described above, AlN is
Due to poor wettability with metal, metallization was not possible and it was difficult to use as a substrate. Further, for example, Japanese Patent Laid-Open No. 50-
75208 and Japanese Patent Laid-Open No. 59-40404, AlN
Oxidizing the surface of the substrate and then metallizing it.
As in 3-102310, a technique is known in which a metal oxide is first provided on the surface of an AlN substrate, and then metallization is performed. Cannot be applied to the co-firing method for the purpose of forming a metallized metal layer and AlN.
Since a layer having a relatively low thermal conductivity is interposed between the substrate and the substrate, there is a drawback in that a decrease in thermal conductivity cannot be avoided.

[0004]

The present invention adopts the following means in order to solve the above problems. The high thermal conductivity aluminum nitride sintered body of the invention of claim 1 comprises 100 parts by weight of aluminum nitride and 4 of the periodic table.
Nitrides of borides of the elements a, 5a, 6a , Zr and Hf
And one or more compounds selected from nitrides of Group 5a elements of the Periodic Table, in total amount of 0.
1 to 3 parts by weight. High thermal conductivity aluminum nitride sintered body according to the invention of claim 2
Is 100 parts by weight of aluminum nitride and 4 of the periodic table.
a, 5a, 6a group boride and 4a, 5 of the periodic table
One or more compounds selected from nitrides of Group a elements
If the amount of Ti nitride is less than 1 part by weight,
It is characterized in that it is composed of a lower part and a total amount of 0.1-3 parts by weight
And

Group 4a elements of the periodic table are Ti, Zr, H
f, the 5a group elements are V, Nb, and Ta, and the 6a group elements are Cr, Mo, and W. Claim
In the invention of item 1, boride of 4a, 5a, 6a group elements of the periodic table, nitrides of Zr and Hf, 5a of the periodic table
One or more compounds selected from nitrides of group elements correspond to 100 parts by weight of AlN in total in terms of metal elements .
However, the reason why the amount is 0.1 part by weight or more and 3 parts by weight or less is that if the amount is less than this range, the wettability of the AlN sintered body with the metal is not improved. This is because the high thermal conductivity of the body is deteriorated and the sinterability is deteriorated. In the invention according to claim 2, 4 of the periodic table
a, 5a, 6a group boride and 4a, 5 of the periodic table
One or more compounds selected from nitrides of Group a elements
If the amount of Ti nitride is less than 1 part by weight,
The same as above, with a total amount of 0.1 to 3 parts by weight
For the reason.

In the present invention, the above components alone are sufficient,
If necessary, a sintering aid such as Y ₂ O ₃ or CaO may be added to AlN1.
You may contain in the range which does not exceed 5 weight part with respect to 00 weight part. When the relative density (density% with respect to the theoretical density) of this sintered body is 90% or more, the effect of high thermal conductivity of AlN is large, and the adhesive strength of metallization is large.

The high thermal conductivity aluminum nitride sintered body of the third aspect of the present invention is obtained by adding carbides of elements of groups 4a, 5a and 6a of the periodic table to the inventions of the first and second aspects,
The gist is that 100 parts by weight of aluminum nitride and one or more kinds selected from boride of 4a, 5a, and 6a group elements of the periodic table and nitride of 4a and 5a group elements of the periodic table. From the compound and one compound or two or more compounds selected from carbides of elements of groups 4a, 5a and 6a of the periodic table, the total amount is 0.1 to 3 parts by weight in terms of metal element. It is characterized by

The total amount of the above boride, nitride and carbide is 0.1 to 3 parts by weight with respect to 100 parts by weight of AlN, which is the same as in the inventions of claims 1 and 2 from this range. This is because if the amount is small, the wettability of the AlN sintered body with the metal is not improved, and if it is larger than this range, the high thermal conductivity of the AlN sintered body deteriorates and the sinterability deteriorates. Also, A
In the present invention, 1N may also contain Y ₂ O ₃ or CaO in an amount of 5 parts by weight or less, as in the inventions of claims 1 and 2 .

According to the invention described in the claims , AlN powder, the above-mentioned boride powder, nitride powder, or carbide powder in addition to the sintering aid powder, if necessary, is molded by a mold or the like, Normal compounds such as N 2, B, C, etc. can be obtained by sintering in a non-oxidizing atmosphere such as N ₂ , Ar, NH ₃ decomposition gas, H _2, etc., or by using a compound which finally becomes boride, nitride, carbide. It can be obtained by sintering in the presence.

[0010]

[Action] Periodic Table of the 4a, 5a, borides 6a group element and / or the Periodic Table of the 4a, nitrides 5a group element, claim
In the case of the invention of No. 3, in addition to that, 4a, 5a of the periodic table,
Since the carbide of the 6a group element does not form a solid solution in the AlN particles but exists between the AlN particles, that is, between the particles, and bonds with the metal, the present invention improves the wettability of AlN with the metal. Seem. Further, the thermal conductivity is usually deteriorated when the additive is present between the grains, but the present invention is effective even though the above-mentioned boride, nitride or carbide is present between the grains of AlN. It has been found that the high thermal conductivity of is not impaired. The reason is that the added compound is A
without reacting with 1N to form other compounds,
Also, since it does not exist so as to cover the entire AlN particles, A
It is considered that the bond between the 1N particles is not impaired and the wettability between AlN and the metal can be improved while maintaining the original characteristics of AlN.

[0011]

EFFECTS OF THE INVENTION The high thermal conductivity aluminum nitride sintered body of the present invention is formed by adding aluminum nitride to 4a, 5a, 6 of the periodic table.
Borides of Group a elements and / or 4a, 5a of the Periodic Table or nitrides of Group 5a elements, or in addition, 4a, 5 of the Periodic Table
By containing the carbides of the a and 6a group elements, the wettability with metal can be improved without impairing the excellent thermal conductivity of aluminum nitride. Since the present invention does not provide a layer of oxide or the like on the surface of the substrate during metallization, the metallized metal layer is directly bonded to the AlN substrate, and thus has excellent properties in bonding strength and thermal conductivity. By using the present invention for a substrate such as an IC, an electronic component having excellent heat dissipation can be obtained. However, unlike the prior art, the surface of the substrate is not required to be treated, and the multilayer substrate can be co-fired. Can be easily obtained.

[0012]

An embodiment of the present invention will be described. In this example, 100 parts by weight of AlN powder having an average particle size of 1.0 μm was added with a predetermined amount of a boride, a nitride, and a carbide in terms of metal shown in Table 1 and mixed, and then wet in ethanol for 4 hours. A raw material powder was prepared by mixing, and then a sample for measuring density and thermal conductivity and a sample for measuring wettability with metal were obtained. To measure the density and thermal conductivity, the raw material powder is 11 mm in diameter and 3 in thickness.
170 mm after molding at a molding pressure of 1.5 ton / cm ²
The sample was obtained by performing atmospheric pressure sintering for 1 hour in a nitrogen atmosphere at 0 ° C. The density was measured as a relative density (apparent specific gravity ratio% to the theoretical density), and the thermal conductivity was measured by a laser flash method after flattening the sample to a thickness of 2 mm.

The wettability with metal was measured as the adhesive strength of metallization. The adhesive strength of the metallization is obtained by molding the raw material powder into 30 × 10 × 5 mm at a molding pressure of 1.5 ton / cm ² and then applying a paste containing W powder (average particle size 1.0 μm) that is usually used for metallization. 2x2 on the surface
mm, thickness of about 20 μm, dried and sintered under normal pressure at 1700 ° C. for 1 hour under normal pressure, and then a Ni layer of 2 to 5 μm is formed on the surface of the sintered body by electrolytic Ni plating. 8
After sintering at 50 ° C for 10 minutes, a 1 × 1 mm Kovar (nickel alloy containing cobalt and iron) plate was brazed at 930 ° C for 5 minutes using a eutectic silver braze, and the adhesive strength was measured as peel strength. did. This peel strength is the strength when the lead wire joined to the Kovar plate is pulled in the direction perpendicular to the bonding surface at a rate of 0.5 mm / sec and the Kovar plate is peeled from the sintered body.

Table 1 shows the measurement results of relative density, thermal conductivity and peel strength. In Table 1, the unit of thermal conductivity is [c
al / cm. sec. ℃], the unit of peel strength is [k
g / mm ² ]. Sample No. 1a to 6a are billed
Nos. 1 and 2 are examples of the invention and examples outside the scope. 1b and 2b are an embodiment of the invention of claim 3 and an example outside the scope. Also, except for the composition shown in Table 1, all are Al
N, and the unit of the content of the composition is parts by weight in terms of metal based on 100 parts by weight of AlN.

According to the present example, as shown in Table 1, AlN is one selected from boride of 4a, 5a and 6a group elements of the periodic table and nitride of 4a and 5a group elements of the periodic table. Or two or more compounds, or in addition to 4a, 5 of the periodic table
High thermal conductivity is obtained by including both the compound of one or two or more compounds selected from the carbides of the a and 6a group elements in a total amount of 0.1 to 3 parts by weight in terms of the metal element. It was found that a sintered body having high peel strength, that is, good wettability with metal can be obtained. In addition, boride of 4a, 5a and 6a elements of the periodic table other than those shown in Table 1 and nitride of 4a and 5a elements of the periodic table, or 4a, 5a and 6a of the periodic table in addition thereto Similarly to the samples shown in Table 1, the samples using the carbides of the group elements have
By adding 0.1 to 3 parts by weight in terms of metal with respect to N, a sintered body having high thermal conductivity and good wettability with metal was obtained.

A conventional AlN sintered body (relative density 99
%) Has a thermal conductivity of 0.14 to 0.24 cal / cm. se
c. C, peel strength is less than 0.5 kg / mm ² . or,
The thermal conductivity of Al ₂ O ₃ (relative density 99%) is 0.04 to
0.07 cal / cm. sec. The peel strength is 2 ~
It is 5 kg / mm ² . AlN powder (average particle 1.0 μm)
CaO was added as a sintering aid to a mixture obtained by adding 3 parts by weight of Mo ₂ B (average particle size: 2.0 μm) to 100 parts by weight in terms of Mo to determine relative density, thermal conductivity, and peel strength. It was measured. The results are shown in Table 2.

[Table 2] As can be seen from Table 2, up to 5 parts by weight of CaO, the sinterability, thermal conductivity and peel strength were similar to those without CaO, but 10 parts by weight of CaO was added. When added, the amount of precipitates, which is thought to be caused by the liquid phase of Ca ₃ Al ₂ O ₆ or the like generated during firing on the metallized surface after firing, becomes severe and the peel strength cannot be measured. I understood.

Claims (3)

[Claims] 1. A material selected from the group consisting of 100 parts by weight of aluminum nitride, boride of 4a, 5a and 6a group elements of the periodic table, nitrides of Zr and Hf, and nitride of 5a group element of the periodic table. 1. A high thermal conductivity aluminum nitride sintered body, which comprises 0.1 to 3 parts by weight in total of one kind or two or more kinds of compounds in terms of metal elements. 2. One part or two selected from 100 parts by weight of aluminum nitride, boride of 4a, 5a and 6a group elements of the periodic table and nitride of 4a and 5a group elements of the periodic table.
A high thermal conductivity aluminum nitride sintered body, characterized in that the compound of one kind or more is converted into a metal element and the amount of Ti nitride is 1 part by weight or less and the total amount is 0.1 to 3 parts by weight. . 3. One part or two selected from 100 parts by weight of aluminum nitride, boride of 4a, 5a and 6a group elements of the periodic table and nitride of 4a and 5a group elements of the periodic table.
0.1 to 3 weights in total of both compounds, which are one or more compounds and one or two or more compounds selected from carbides of 4a, 5a, and 6a group elements of the Periodic Table. And a high heat conductive aluminum nitride sintered body.