JPS63242972A - 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] [Object of the invention] (Industrial application field) The present invention relates to a method for manufacturing an aluminum nitride sintered body,
Specifically, the present invention relates to a method for producing an aluminum nitride sintered body with good thermal conductivity.

(Prior art) Aluminum nitride (A)N) is used as a heat-resistant material because it shows little strength loss even at high temperatures and has excellent chemical resistance. It is also attracting attention as a heat dissipation material for semiconductor devices. Such AiN typically has no melting point and is
Because it decomposes at high temperatures above °C, it is used as a sintered body except for applications such as thin films.

By the way, the A, 17N sintered body is usually obtained by molding and sintering AiN powder. However, A, /
When N powder is used alone, the sinterability is poor, so it is difficult to obtain a dense sintered body using methods other than hot pressing.

For this reason, when performing pressureless sintering, AI! A rare earth oxide or alkaline earth oxide powder is added to the N powder as a sintering aid, and then molded and sintered. Furthermore, for the purpose of improving the thermal conductivity and strength of the lt'N sintered body and sintering it at a low temperature, a method of adding compound powder containing other elements, particularly transition elements, and sintering it is also carried out.

However, in the method of manufacturing A,11'N sintered bodies by adding the above-mentioned sintering aids etc. to A-N powder, the presence of grain boundaries and non-uniformity of added elements occur, so that the results are not always as expected. There was a problem that high thermal conductivity and high strength could not be achieved. This is mainly due to the fact that the compound powder such as an auxiliary agent added to the A, 17N powder used is too large or the dispersibility is poor.

(Problems to be Solved by the Invention) The present invention has been made to solve the above-mentioned conventional problems, and aims to provide a method for producing a dense and highly thermally conductive AiN sintered body. It is.

[Structure of the Invention] (Means for Solving the Problems) The invention of Section 1 of the present application includes aluminum nitride powder containing a metal alkoxide [M (OR) x , where M is the central atom, O
R is an alkoxy group, X is a valence of M] or a derivative thereof, and the metal alkoxide, its derivative, or its decomposition product is attached to the surface of the aluminum nitride powder, and the metal alkoxide or a derivative thereof, or a decomposition product thereof is attached to the aluminum nitride powder.

Examples of the rare earth elements include Y, La.

Ce' s S 1D y s N d s G d
Examples include s P r , Ho, Er, Yb, etc., especially Y and La.

Ce is preferred. Furthermore, examples of alkaline earth elements include B e SM g s Ca s S r , B
Among them, Ca, Sr, and Ba are particularly preferred.

OR forming a metal alkoxide is an alkoxy group, R
Generally, an alkyl group having 1 to 5 carbon atoms or a phenyl group is preferable.

Typical examples of the metal alkoxide derivatives include acetylacetonate or a salt thereof.

Examples of methods for bringing the metal alkoxide or its derivative into contact with and adhering to the A-N powder include a method of mixing or dissolving it with a binder or solvent and adding it to the A-N powder;
A method of dispersing the powder in a solvent, adding a liquid or solution metal alkoxide or its derivative, filtering and drying, evaporating the metal alkoxide or its derivative,
, a method of exposing ffN powder to the vapor, etc. may be adopted. When a metal alkoxide or its derivative is used as a solution, it may be used in a state in which decomposition is advanced by adjusting the solution temperature, adding moisture, acid, or alkali, or the like.

For the above-mentioned sintering, a pressureless sintering method, a hot press method, etc. can be adopted. In the case of pressureless sintering, a binder is added to the aluminum nitride powder to which the metal alkoxide, its derivative, or its decomposition product is attached, and crosstalk, granulation,
After sizing, molding is performed using a mold press, isostatic press, sheet molding, or the like. At this time, before adding the binder, the AI! The metal alkoxide or its derivative adhering to the surface of the N powder is further decomposed by means such as drying. In addition, before molding the aluminum nitride powder to which the metal alkoxide, its derivative, or its decomposition product is attached, the aluminum nitride powder is coated with IV powder.
Group a transition elements (e.g. Yl, Zr% Hf, etc.), group V
Group a transition elements (e.g. VSNb, Ta, etc.), IVa
Group transition elements (e.g. Cr, MO, W, etc.), Group 1a transition elements (e.g. M n % Re, etc.), Group II transition elements (e.g. M n % Re, etc.)
For example, FQ.

A powder of a compound (oxide, nitride, fluoride, oxyfluoride, oxynitride, etc.) of Co , N 1, etc.) may be blended. Subsequently, the molded body is heated, for example, in a N2 gas stream to remove the binder, and then sintered under normal pressure. The sintering temperature depends on the AfN powder used, metal alkoxide or its derivative,
It may be appropriately selected depending on other additives and the like.

The second invention of the present application is to add metal alkoxide [M (OR) x , where M is the central atom and O
R is an alkoxy group, X is the valence of M] or a derivative thereof, and Group IVa, Group Va, Group VI
Metal alkoxide containing a transition element of group a, group VIIa, or group II as a central atom [M-(OR-)x', where M' is the central atom, OR- is an alkoxy group, and X'' is the valence of M. or a derivative thereof, to deposit each metal alkoxide, its derivative, or its decomposition product on the surface of the aluminum nitride powder;
This is a method for producing aluminum nitride, comprising the steps of molding and sintering aluminum nitride powder to which each metal alkoxide, its derivative, or its decomposition product is attached.

Examples of the Group 1a transition elements include Yl, Zr
, Hr, etc., as group Va transition elements, for example, V, N
b%Ta etc. as a group IVa transition element, for example, C
r5M01W etc. as group VIIa transition elements,
For example, M ns Re and the like can be mentioned, and examples of the Group Ⅰ transition element include Fe s Co and Ni.

OR'' forming the metal alkoxide is an alkoxy group, and R'' is preferably an alkyl group having 1 to 5 carbon atoms or a phenyl group.

Representative examples of the derivatives of each of the metal alkoxides mentioned above include acetylaceto 9 or a salt thereof.

The above-mentioned metal alkoxides or their derivatives can be brought into contact with and adhered to the AJN powder, for example, by mixing or dissolving them with a binder or solvent and adding them to the lt'N powder, or by dispersing the lt'N powder in a solvent and forming it into a liquid or solution. Adding the metal alkoxide or its derivative, filtering and drying, evaporating the metal alkoxide or its derivative, Aj? A method such as exposing N powder to the vapor may be adopted.

When each metal alkoxide or its derivative is prepared as a solution, it may be used in a state in which decomposition proceeds by adjusting the solution temperature, adding moisture, acid, or alkali, or the like. Also,
When used as a composite alkoxide, both may be composited by means such as reflux, or one component may be added in the form of a salt to produce a composite alkoxide.

The above-mentioned sintering may be performed by a method similar to that of the first invention of the present application described above.

(Function) According to the present invention, by bringing the metal alkoxide or its derivative into contact with the A-N powder, it is possible to uniformly add additive elements such as sintering aid components to the A-N powder. can. This means that metal alkoxides or their derivatives are easily decomposed by moisture on the surface of the AiN powder or added moisture, acid, heat, etc., and either adhere to the surface of the AiN powder as fine particles of about 0.5 μm or less or form a coating on the surface of the AiN powder.
This is due to the ability to cover the NO powder. Therefore, A to which such a metal alkoxide or its derivative is attached
, By molding and sintering the ffN powder, the sinterability can be improved even if the amount of additives is reduced, and the reaction between the additive and oxygen on the surface is promoted and the mixture is transferred into the A, ffN powder. By suppressing oxygen diffusion, etc., it is possible to produce an lt'N sintered body that is dense, has high thermal conductivity, and has high strength.

(Example of the invention) Examples of the present invention will be described in detail below.

Examples 1 to 3 First, three types of Y (
OC4H9) 3 was immersed in a benzene solution, stirred, filtered, and the residue was air-dried to prepare a powder.

When the weight of Y2O3 contained in these three powders was measured, they were approximately 1%, 3%, and 5%. Continuing,
Each of these powders was granulated by adding 7% by weight of paraffin as a binder, and then press-molded at a pressure of 300 Kl/cd to obtain a green compact of 5Q x 50 x 80 mm. After heating these green compacts to 700°C in a nitrogen gas atmosphere to remove paraffin, they were stored in a carbon container and sintered under normal pressure at 1800°C for 2 hours in a nitrogen gas atmosphere. A N sintered body was manufactured.

Comparative Examples 1 to 3 Contains 1% by weight of oxygen as an impurity and has an average particle size of 0.9
1.3.5% by weight of Q and 9 μm Y2O3 were added to μm A and 17N powders, mixed in a ball mill to prepare powder, and then molded and sintered in the same manner as in Example 1. And three kinds of A, f? A N sintered body was manufactured.

Therefore, the density and thermal conductivity of the AiN sintered bodies of Examples 1 to 3 and Comparative Examples 1 to 3 were measured, and the produced phase was identified by X-ray diffraction. The results are shown in Table 1 below. In addition, the thermal conductivity is 10. The specimen was ground into a disk with a thickness of 2.5 tu and a test piece of 71I+1 using a laser flash method.

Examples 4-7 lt' with an oxygen content of 3.6% by weight and an average particle size of 2.2 μm
0.2 mol/i concentration benzene solution, Ca (OC2H5) 2 for N powder
A 0.2 mol/i concentration ethanol solution of Zr (OC
A powder was prepared in the same manner as in Example 1 by adding a 0.4 mol/i concentration butyl acetate solution of 4Hll)3 and Z'02 powder with an average particle size of 3 μm in terms of the oxide shown in Table 2 below, Furthermore, four types of A and t'N sintered bodies were manufactured by molding and firing.

However, in the case where Zr 02 was added, the powder was ground and mixed using a ball mill.

Comparative Examples 4 to 6 Contains oxygen! 3.8% by weight, average particle size 2.2μm lt
Y2O3 with an average particle size of 2.5 μm, CaO with an average particle size of 3 μm, and Zr02 powder with an average particle size of 3 μm were added to the 'N powder in the proportions shown in Table 2, and mixed in a ball mill to form the powder. After the preparation, three types of lt'N sintered bodies were manufactured by molding and sintering in the same manner as in Example 1.

Therefore, the density and thermal conductivity of the A/N sintered bodies of Examples 4 to 7 and Comparative Examples 4 to 6 were measured. The results are also listed in Table 2.

Table 2 As is clear from Tables 1 and 2 above, the A, i7N sintered body produced by the method of the present invention has high thermal conductivity. This means that the generated phase is the auxiliary component and A, g2
As can be seen from the fact that the product is almost similar to that expected from the phase diagram of AJ! This is thought to be to suppress oxygen diffusion into N. The method of blending auxiliary powder as in the comparative example results in a non-uniform system, and A, i'
Formation of ON and ineffective auxiliary components are observed.

It is also effective to mix two or more types of auxiliary components at the same time, but in that case, if a mixed solution of two or more types of metal alkoxides is used, it is possible to uniformly add the auxiliary agents at a micro level. At this time, since one of the components functions preferentially to the A and 17N powders, non-uniformity of the A/N sintered body does not occur.

Furthermore, the A/N sintered bodies of Examples 5 to 7 and Comparative Example 5 were ground to a width of 41 mm. ! 11 Thickness 3111% Length 4
0 m square bars were manufactured, and these were used as specimens for measuring bending strength.
The three-point bending strength was measured under the conditions of n.

As a result, the sintered bodies of Examples 5 to 7 had a weight of 58 to 65 g/l.
! The strength of the sintered body of Comparative Example 5 was 55 g/+m2, whereas the strength of the sintered body of Comparative Example 5 was 112 g/m2. In the system (Example 6) in which the second additive (Zr 02 ) was added in this way,
It can be seen that it has a good effect on the strength improvement effect of Z'02.

[Effects of the Invention] As detailed above, according to the present invention, A7N sintered bodies with high density, high strength, and high thermal conductivity can be easily manufactured, and can be used as various structural parts and heat sinks for semiconductor devices. It has remarkable effects such as being able to be used effectively for parts, etc.

Claims (3)

[Claims] (1) Metal alkoxide containing a rare earth element or alkaline earth element as a central atom is added to aluminum nitride powder [
M(OR)_x, where M is the central atom, OR is an alkoxy group, and x represents the valence of M] or a derivative thereof is brought into contact with the surface of the aluminum nitride powder to form the metal alkoxide, its derivative, or its derivative. A method for producing aluminum nitride, comprising the steps of depositing a decomposition product, and molding and sintering the aluminum nitride powder to which the metal alkoxide, its derivative, or its decomposition product is deposited. (2) Before molding the aluminum nitride powder to which the metal alkoxide or its derivative or its decomposition product is attached, group IVa, group Va, group
2. The method for producing an aluminum nitride sintered body according to claim 1, characterized in that compound powder of transition elements of group VIa, group VIIa, and group VIII is blended. (3) Metal alkoxide with a rare earth element or alkaline earth element as the central atom [
M(OR)_x, where M is the central atom, OR is an alkoxy group, x represents the valence of M] or its derivatives, and Group IVa, Group Va, Group VIa, Group VIIa,
Metal alkoxide containing a group VIII transition element as the central atom [M'(OR')_x_', where M' is the central atom, OR
' is an alkoxy group and 1. A method for producing aluminum nitride, comprising the steps of molding and sintering aluminum nitride powder to which an alkoxide, a derivative thereof, or a decomposition product thereof is attached.