JPS63239158A - 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 [Field of Industrial Application] The present invention relates to a method for manufacturing an aluminum nitride (AlN) sintered body used for circuit wiring boards, ceramic packages for mounting semiconductor integrated circuits, and the like.

[Prior Art] AlN sintered bodies have high thermal conductivity and electrical insulation, as well as excellent mechanical strength and chemical stability, so they are used as substrates for circuit wiring, ceramic packages for mounting semiconductor integrated circuits, etc. Its use is being considered.

Since this AlN has a high covalent bonding property and is difficult to sinter, when obtaining an AlN sintered body, a small amount of sintering aid is added to the AlN raw material powder, and the
Heat treatment and sintering at 0°C to 2000°C. Examples of the sintering aid include alkaline earth metal oxides, carbonates, and oxalates as disclosed in JP-A-61-10071, or as disclosed in JP-A-60-127267. samarium oxide, yttrium oxide,
Gadolinium oxide etc. are used.

[Problems to be Solved by the Invention] By the way, the thermal conductivity of an aluminum nitride sintered body obtained by adding a sintering aid to aluminum nitride raw powder and sintering it at normal pressure is the same as that of aluminum nitride. This improvement is desired since it is significantly lower than the theoretical thermal conductivity (<320 w/m-K).

Therefore, an object of the present invention is to provide a method for manufacturing an aluminum nitride sintered body having high thermal conductivity.

[Means for Solving the Problems] The present invention for achieving the above object is based on Al□03 and/or
or AIN in which part of the nitrogen in AlN is replaced with oxygen,
At least one type selected from Ox (where X indicates the amount of substituted oxygen) is 0.58 to 9.4 in terms of oxygen
A molded body of a mixture of 100 parts by weight of aluminum nitride M material powder containing 2% by weight and 0.5 to 6 parts by weight of a sintering aid containing at least IM metal powder selected from alkaline earth elements and rare earth elements. The oxygen that forms and constitutes the Al2o3 and/or A I N, -xoX reacts with the metal powder, and the A I 203 and/or A
A method for producing an aluminum nitride sintered body, characterized in that the molded body is fired in a nitrogen gas atmosphere so that aluminum constituting IN1-xO reacts with nitrogen to produce aluminum nitride. It is something.

[Function] At least one type of gold FA selected from alkaline earth elements and rare earth elements as a sintering aid (hereinafter, alkaline earth metals are referred to as Me and rare earth metals are referred to as Re) is added to the oxygen ( Normally, it is thought to be contained in the form of AlN1-xOx, in which part of the nitrogen in A1203 and/or AlN is replaced with oxygen) to promote sintering and reduce the thermal conductivity of the sintered body. Participate in the improvement. That is, in the sintering process, for example, A' 120 s of oxygen and the sintering aid M
A metal oxide is produced by combining with e or Re, and Al□
Al of No. 03 and nitrogen contained in the raw material powder or atmosphere combine to generate AlN.

The reaction in the case of Me can be shown by the following formula.

Al o +3/4Me+1/4N2→3/4MeO・
Al2O3+1/2 AlN 2 A 1 0 +2/3 Me +2/3 N2-
The reaction in the case of 2/3 MeO-2Al203+4/381N Re can be shown by the following formula.

UAI O+15/4Re +15/8N2-5/
4 R1AI O+15/4AlN AI O+Re +1/2 N →Re AlO3
+AlN The generated composite oxide or oxide gathers at the grain boundaries of the burnt AlN body, while the generated AlN becomes part of the crystal grains. By using Me or Re as a sintering aid, AlN with high thermal conductivity is generated, which reduces the generation of metal oxides with low thermal conductivity, resulting in higher overall thermal conductivity. .

In contrast, conventional alkaline earth gold R oxide M+30
) as a sintering aid, for example, AlN
The A 1203 inside reacts with this MeO as follows.

AlO3+2eo→MeO-Al2032Al 0
+Me O-+Me O-2Al203 As is clear from this, when gold R oxide (Men) is used as a sintering aid, only a composite oxide is produced, and Al
N is not generated.

Therefore, a large amount of composite oxides with poor thermal conductivity gather at the grain boundaries, and as a result, an AlN sintered body with high thermal conductivity cannot be obtained. Similarly, when used as AlN, Al2o3 in AlN and rare earth oxide react as follows.

5Al 0 +3Re O-2Re3At5AI
O+Re203-2ReAl03 In this case, only oxides with poor thermal conductivity are generated, and Al
No N is generated, and as a result, the thermal conductivity of the sintered body is low.

[Example] Metallic calcium with an average particle size of 4.58 μm was added to 100 parts by weight of AlN powder with an average particle size of 0.92 μm, which was confirmed to contain 0.58% by weight of oxygen using a metal oxygen concentration analyzer. Adding 0.5 parts by weight of a sintering aid consisting of powder,
For the total of AlN powder and sintering aid (100 ffl parts), 8 parts by weight of polymethyl methacrylate as a binder, 1 part by weight of oleic acid as a deflocculant, and 40 parts by weight of toluene that has been dehydrated with a molecular sieve. These were stirred and mixed in a ball mill for 20 hours to obtain a uniformly dispersed slurry. Note that the oxygen in AlN is usually aluminum oxide (Al203) and/or aluminum nitride (AlN) in which part of the nitrogen is replaced with oxygen.
It is thought that it is contained in the form of lN1-xOx.

Next, the obtained slurry was deaerated and then molded by a doctor blade method to obtain a ceramic green sheet with a thickness of 1.0 nn.

Next, attach the ceramic green sheet to 50111X 5Q
The pieces cut to a size of nm were stored in a sheath made of an AlN sintered body, subjected to debinding treatment at 500°C for 2 hours in an N2 gas atmosphere, and then heated to 18 nm in an N2 gas atmosphere at substantially normal pressure.
It was baked at 00°C for 30 minutes.

Next, both surfaces of the obtained AlN sintered body were lap-polished to a thickness of 0.51 mm to obtain Sample 1. For the obtained sample, the bulk density and true specific gravity (3,
26g/cm3) to relative density (bulk density/true specific gravity
100) was calculated, and after gold vapor deposition was performed on each main surface of the obtained sample, carbon vapor deposition was further performed and the thermal conductivity was measured using the laser flash method.
The results shown in the table were obtained. In the table, the Al of each sample No.
Oxygen content in N raw material powder, type and amount of sintering aid,
Thermal conductivity and relative density are shown.

sample? k), In 2 to 88, AlN sintered bodies were prepared in the same manner as in 1, except that the oxygen content and the type and amount of the sintering aid were changed, and the thermal conductivity, Relative density was measured.

In the above table, oxygen content (Al203 and/or A
I N,, contained in the form of Ox) is 0°58% by weight
The sample amount is 15 to 2 within the range of 1 to 20.
0 is a comparative example outside the scope of the present invention.

Sample No. 19 is 1, in which 2.0 parts by weight of Ca0 (calcium oxide), which is an oxide of an alkaline earth metal, is added without adding any metal powder as a sintering aid.
The thermal conductivity is low (125 and 110w; / m-K) The amounts of Ca and Nd as sintering aids in samples Nos. 15 and 17 are 0.2 parts by weight each, which is small, so the thermal conductivity of the sintered bodies is low and the purpose of the present invention cannot be achieved. Also, sample Nα16
The amounts of Ca and Nd in No. 1 and No. 18 are 7.0 parts by weight, which are too large, resulting in a low thermal conductivity of the sintered body, making it impossible to achieve the object of the present invention. Therefore, sample No.1
5 to 18 are also outside the scope of the present invention.

As is clear from samples Nα1 to Nα8, Ca was used as a sintering aid.
When adding (calcium), Nd (neodymium), M(+ (magnesium), Sl (samarium) in the range of 0.5 to 6.0 parts by weight, the thermal conductivity increases from 139 to 168 w.
/m −K, which is larger than the value of the comparative example shown in sample NQ 19.20.

As shown in samples Nα9 to 12 (, Nd, Ca, Mg, ce
Even if multiple types of (cerium) are added, a higher thermal conductivity than the comparative example can be obtained.

As shown in test f4NQ13 (Nd, Ca metal powder, Y
Even if 2 o3 (yttrium oxide) is added, metal (Nd
, Ca) The powder addition effect is not lost, and sample 111
As shown in 0.14, CaCO3 is added to Ce and Mg metal powder.
Even if 0.5 part by weight is added in terms of CaO, the metal powder (C
e, Mg) The addition effect is not lost.

Sample N021 with oxygen content of 0.93% by weight
-40, the same effects as those of sample islands 1-20 are occurring. That is, according to the present invention, the metal powder is
The thermal conductivities of Samples 21 to 34, in which ~6.0 parts by weight was added, are higher than those of Samples Nα35 to 40, which are comparative examples.

Among the samples whose oxygen content is 9.42% by weight, 41
-60 also produced the same effects as those of samples No.1-20. That is, the thermal conductivity of Samples 41 to 54 to which 0.5 to 6.0 parts by weight of metal powder was added according to the present invention is that of Sample No., which is a comparative example.

higher than those of 55-60.

In sample Nos. 61 to 74, the oxygen content was 0.311i
It is said to be 1%. When the oxygen content is so low, high thermal conductivity cannot be obtained even if metal powder is added in the range of 0.5 to 6.0 parts by weight.

Therefore, samples Nos. 61 to 74 are outside the scope of the present invention.

For samples 75 to 88, the oxygen content was 18.95% by weight. When the oxygen content is so high, high thermal conductivity cannot be obtained even if metal powder is added in a range of 0.5 to 6.0 parts by weight.

Therefore, samples Nos. 75 to 88 are outside the scope of the present invention.

Between samples within the scope of the invention, 1 to 14.21 to 34.41
The thermal conductivity of ~54 is in the range of 136 to 185 w/m·K, which is clearly higher than that of those outside the range of the present invention.

[Modifications] The present invention is not limited to the above-described embodiments, and for example, the following modifications are possible.

(1) Alkaline earth metals other than Ca and Ma (e.g.
Sr, Ba) or rare earth metals other than Nd, Ce, Sn (eg, La, Pr) may be used as sintering aids.

(2) Compounds other than Y2O3 and CaO (
For example, M(10, Sr O, Ba 01 MgCO3,
CaCO3, SrCO3, BaCO3, La2O3, C
eO2, Pr02, Nd203) may be included in the sintering aid to the extent that they do not inhibit the effects of the present invention.

(3) Adjust the firing temperature to 1600 to 190, for example.
There is no problem in varying the temperature within the range of 0°C.

[Effects of the Invention] As is clear from the above, according to the present invention, the thermal conductivity is 135 w/m-K or more due to the action of the alkaline earth or rare earth metal, despite the fact that it is essentially pressureless sintering. A of
An IN sintered body can be obtained.

Claims (1)

[Claims] At least one type selected from Al_2O_3 and/or AlN_1_-_xO_x in which a part of the nitrogen of AlN is replaced with oxygen, 0.58 to 9.42% by weight in terms of oxygen
Forming a molded body of a mixture of 100 parts by weight of aluminum nitride raw material powder containing 0.5 to 6 parts by weight of a sintering aid containing at least one metal powder selected from alkaline earth elements and rare earth elements, The Al_2O_3 and/or Al
The oxygen constituting N_1_-_xO_x reacts with the metal powder, and the Al_2O_3 and/or Al
A method for producing an aluminum nitride sintered body, comprising firing the compact in a nitrogen gas atmosphere so that aluminum constituting N_1_-_xO_x reacts with nitrogen to produce aluminum nitride.