JPH06172037A - Production of aluminum nitride sintered compact - Google Patents

Abstract

PURPOSE:To improve the corrosion resistance by converting the oxygen content in AlN powder subjected to the oxidation treatment into Al2O3, mixing the AlN powder with a Ca compound and a Y compound so as to provide a specific molar ratio expressed in terms of oxides and sintering the resultant mixture. CONSTITUTION:AlN powder subjected to the oxidation treatment is mixed with a Ca compound such as CaCO3 and a Y compound such as Y2O3 as a sintering assistant in the total amount of 0.5-10wt.% expressed in terms of oxides and the oxygen content in the AlN powder is converted into Al2O3 so as to provide 25<=CaO<=55, 10<=Y2O3<=20 and 35<=Al2O3<=65 expressed in terms of molar ratios. An adequate amount of a binder is then added to the resultant mixture. Granulating and press forming are carried out to heat the formed compact in an N2 gas atmosphere. Thereby, the binder is removed. The heated compact is then placed in a container made of BN and sintered at about 1600 deg.C under ordinary pressure in an N2 gas atmosphere for 2-8hr to afford the objective AlN sintered compact having high thermal conductivity and excellent corrosion resistance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum nitride sintered body which is effectively used for insulating substrates, heat sinks, semiconductor package materials, etc., and has good thermal conductivity and excellent corrosion resistance to acids and alkalis. The present invention relates to a manufacturing method of.

[0002]

2. Description of the Related Art The conventional aluminum nitride (AlN) sintered body has high thermal conductivity and excellent electric insulation performance, and has a thermal expansion coefficient close to that of silicon, so that it is suitable for high integration and high density of LSI in recent years. It is regarded as a promising material for the corresponding high heat insulating substrate. When AlN is used as a package material for semiconductors, it is manufactured as follows. That is, a sintering aid and a binder were added to and mixed with AlN raw material powder, and the sintered body obtained by sintering was first formed into a green sheet by, for example, a doctor blade method. After that, a conductive material such as tungsten or molybdenum is formed on the wiring pattern or the semiconductor mounting surface and then baked. The baked conductive material is usually subjected to a plating treatment with Au or the like in order to bond with the semiconductor chip.

Although high heat conductivity is required for the above-mentioned Al N sintered body for packaging, it is usually used in the production of the Al N sintered body.
It is necessary to bake at a high temperature of 00 ° C or higher, and it is necessary to sinter at a low temperature for a short time in order to reduce the manufacturing cost.

As an Al N sintered body satisfying the above-mentioned requirements, Al N powder is composed of (a) a rare earth oxide and at least one compound selected from compounds which become these oxides by firing. The powder, and (b) the powder of at least one compound selected from the group consisting of the alkaline earth metal oxides and the compounds which become these metal oxides by firing, are converted into the weight of the oxides, and the total. A method for producing an Al N sintered body, in which 0.01 to 20% by weight is added, followed by molding and firing (Patent Document 1)
61-117160).

However, although the sintered body produced by the method of the above-mentioned Japanese Patent Laid-Open No. 61-117160 is sintered at a low temperature of 1600 to 1700 ° C. and exhibits a thermal conductivity of 79 to 110 W / m · K, There is a problem in the corrosion resistance to acid and alkali when the plating treatment is performed as the di-material. Further, the above-mentioned JP-A-61-1171
In the case of the invention of Japanese Patent No. 60, when sintering at a low temperature of around 1600 ° C., it was necessary to perform firing for a long time in order to increase the thermal conductivity.

[0006]

In view of the above, in order to manufacture a high thermal conductivity Al N sintered body as described above,
In general, it is necessary to bake at a high temperature of 1800 ° C. or higher, and therefore it is necessary to solve the problem of high manufacturing cost. Secondly, when the Al N sintered body is used as a package material for semiconductors, the baked Al N conductive material is usually plated with Au or the like to bond with the semiconductor chip. Therefore, it is necessary to solve the problem of having to have corrosion resistance to acids and alkalis in order to use it as a package material for Al N sintered body.

In order to solve the above-mentioned problems, the present invention provides 1700
It can be sintered at a low temperature below ℃ for a short time and has excellent thermal conductivity.
Moreover, it is an object of the present invention to provide a method for producing an AlN sintered body having excellent corrosion resistance against acids and alkalis.

[0008]

The first aspect of the present invention is a method for producing an Al N sintered body, which comprises adding an oxidized Al N powder, a Ca compound and a Y compound and baking the mixture. Second, the oxygen content in the oxidized Al N powder was converted into Al ₂ O ₃ , and the Ca compound and the Y compound were converted into their oxides, and the respective molar ratios were as follows.
(1) The method for producing an Al N sintered body according to the first aspect of the present invention, which comprises oxidizing and adding within the range described. Thirdly, the Ca compound and the Y compound are converted into respective oxides in a total amount of 0.5% by weight or more based on the Al N powder,
The present invention relates to a method for producing an Al N sintered body according to the second invention, wherein 10% by weight or less is added.

In the present invention, the oxygen content in the oxidized Al N powder is converted into Al ₂ O ₃ , and the Ca compound and the Y compound are converted into oxides as sintering aids, respectively, within the ranges described in (1) above. Need to be satisfied. When the composition deviates from the range described in the above (1), the densification of the AlN sintered body is not sufficiently achieved at the firing temperature of 1700 ° C. or less, and the corrosion resistance to acids and alkalis is remarkably lowered and the thermal conductivity is lowered. Therefore, it cannot be used in the present invention. Ca O as Ca compound, but as the Ca CO _3, Y compound is preferably Y ₂ O _3, no problem be used carbonates, nitrates, hydroxides, fluorides or the like. The total amount of Ca compound and Y compound to be added is in the range of 0.5% by weight or more and 10% by weight or less in terms of oxide with respect to the AlN powder.
l N sintered body is insufficiently densified, and as a result, corrosion resistance against acids and alkalis is significantly reduced, and thermal conductivity is reduced. On the other hand, if it exceeds 10% by weight, the corrosion resistance is good, but the thermal conductivity is lowered, and therefore both cannot be used in the present invention.

[0010]

The present inventor has studied in detail the structure of the Al N sintered body in order to achieve both the thermal conductivity of the Al N sintered body and the corrosion resistance to acids and alkalis. As a result, the Ca compound and Y which are added as a sintering aid are added. Since 50% or more of Ca YAl ₃ O ₇ formed by combining the compound with the Al compound is present as a grain boundary phase in the Al N sintered body, the Al N sintered body is remarkably excellent in corrosion resistance to acid and alkali. It has been found that an Al N sintered body having an effect and a high thermal conductivity can be obtained. The present inventor further pre-oxidizes the starting aluminum nitride powder to form an oxide layer on the surface of the powder, whereby the reaction between the AlN powder and the Ca compound and the Y compound proceeds uniformly and rapidly. Therefore, the present inventors have completed the present invention by finding that the sintering of the AlN powder progresses quickly and the firing time in low temperature firing is shortened.

50% of Ca YAl ₃ O ₇ is used as the grain boundary phase.
In order to generate the above, the oxygen content in the pre-oxidized Al N powder found by the present inventor is changed to Al ₂ O _3.
And the Ca compound and Y compound as sintering aids are converted into oxides, and the respective molar ratios of Ca O, Y ₂ O ₃ and Al ₂ O ₃ satisfy the range described in (1) above. It is necessary to punish. Grain boundary phase components formed from Ca compounds, Y compounds and Al compounds include Ca Al ₄ O ₇ and Ca A
Ca -Al compounds such _{l 2 O 4, Y 3 Al} 5 O 12, YA
It was already known that Y-Al compounds such as l O ₃ exist, but the composition of the sintering aid containing these compounds as the main component also has a high thermal conductivity and corrosion resistance to acids and alkalis. Both decrease.

[0012]

EXAMPLES The present invention will be described with reference to Examples and Comparative Examples. [Examples 1 to 7], [Comparative Examples 1 to 6] Al N powder (average particle size: 2.9 μm, oxygen content: 0.85 wt%) was oxidized at 800 ° C. for 10 minutes to 2 hours in the atmosphere.

[Table 1] The raw materials were pretreated so as to have various amounts of Al ₂ O ₃ (in terms of moles) shown in. Add Ca CO ₃ and Y ₂ O ₃ respectively to this

The composition of the auxiliary oxide shown in Table 1 was used. Then,
After adding 1.5% by weight of molding binder and granulating, 10
A molded body having a diameter of 20 mm and a thickness of 5 mm was formed at a pressure of 00 kg / cm ² .
This molded body was kept in N ₂ gas at 700 ° C. for 2 hours to remove the binder, placed in a boron nitride container, and placed in a N ₂ atmosphere.
The mixture was sintered at 50 ° C. for 2 hours under normal pressure to obtain an Al N sintered body. The thermal conductivity of the obtained AlN sintered body was measured by the laser flash method, and the corrosion resistance test was conducted at 50 ° C. under 1N Na 2 O.
It was measured by a change in weight after being immersed in an H aqueous solution and a 90 ° C. 1N H ₂ SO ₄ aqueous solution for 2 hours. The grain boundary phase was identified and quantified by powder X-ray diffraction.

Ca O, Y ₂ O within the scope of the claims
_In Examples 1 to 5 in which the auxiliary component having a molar ratio converted to ₃ , Al ₂ O ₃ was used, 50% of Ca YAl ₃ O ₇ was used as a grain boundary phase.
Because of the above, the thermal conductivity exceeds 100 W / mK, and it exhibits excellent corrosion resistance and alkali resistance. However, Comparative Example 1
As can be seen in -4, outside the scope of the present claims, Ca
With a sintering aid composition having a molar ratio converted to O, Y ₂ O ₃ , and Al ₂ O ₃ , the ratio of Ca YAl ₃ O _{7 in} the grain boundary phase decreases, and both thermal conductivity and corrosion resistance decrease. Further, as seen in Comparative Example 5, the added amounts of Ca O, Y ₂ O ₃ and Al ₂ O ₃ are within the scope of the present claims, and therefore Ca YAl ₃ O ₇ is 50%.
%, The addition amount of (Ca O + Y ₂ O ₃ ) is 0.
If it is less than 5% by weight, sintering is insufficient and both the thermal conductivity and the corrosion resistance are reduced. On the other hand, if it exceeds 10%, the corrosion resistance is good but the thermal conductivity is insufficient.

[Embodiment 8] Al N raw material powder (oxygen amount: 0.
Al ₂ O ₃ was added to 85% by weight) to make the total oxygen amount 1.25% by weight.
And the present Al N raw material powder were oxidized at 800 ° C. for 60 minutes, and the amount of oxygen in the Al N powder was adjusted to 1.25% by weight, and Ca CO ₃ and Y ₂ O ₃ were used in the examples of [Table 1]. The mixture was mixed so that the oxide molar ratio of 2 was (%). Then, 1.5% by weight of a molding binder was added and granulated, and then 1000
A molded body having a diameter of 20 mm and a thickness of 5 mm was formed at a pressure of kg / cm ² . This molded body was kept in N ₂ gas at 700 ° C. for 2 hours to remove the binder, put into a boron nitride container, and placed in a N ₂ gas atmosphere.
The mixture was sintered at 00 ° C. for 2 to 8 hours under normal pressure to obtain an Al N sintered body. The relationship between the sintering time (hr) and the thermal conductivity of the obtained sintered body is shown in FIG. As shown in FIG. 1, the thermal conductivity increases with the sintering time.
A thermal conductivity of 100 W / mK was obtained in 2 hours upon sintering at (° C). That is, high thermal conductivity was achieved in about half the time required for the conventional method.

[0015]

[Table 1]

[0016]

The effects of the present invention are summarized as follows. (1) The Al N sintered body obtained by the present invention is a sintered body having high thermal conductivity and excellent corrosion resistance to acids and alkalis. (2) It can be sintered at a low temperature near 1600 ℃ for a short time.
l The manufacturing cost of the N sintered body is reduced. Therefore, it has a great industrial value as an AlN manufacturing method in consideration of the productivity of package materials for semiconductors.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between a firing time at 1600 ° C. and a thermal conductivity between Example 8 and a conventional method as a comparative example.

Claims (3)

[Claims] 1. A method for producing an aluminum nitride sintered body, which comprises firing an oxidized aluminum nitride powder and a Ca compound and a Y compound. 2. The oxygen content in the oxidized aluminum nitride powder is converted into Al ₂ O ₃ and the Ca compound and the Y compound are converted into their oxides, and the respective molar ratios are (1) ) The method for producing an aluminum nitride sintered body according to claim 1, wherein oxidation and addition are performed within the range described. 3. The method for producing an aluminum nitride sintered body according to claim 2, wherein the Ca compound and the Y compound are added in a total amount of 0.5% by weight or more and 10% by weight or less with respect to the aluminum nitride powder in terms of oxide.