JP3434963B2 - Aluminum nitride sintered body and method for producing the same - Google Patents

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 applied to various insulating substrate materials, semiconductor element housing package materials and the like, and a method for producing the same, and more specifically, it is fired at a temperature of 1700 ° C. or less. The present invention relates to an aluminum nitride sintered body that can be bonded, has excellent chemical resistance against acids and alkalis, and has good thermal conductivity, and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, the heat generated from a semiconductor device has increased with the high integration of semiconductor elements, and in order to prevent malfunction of the semiconductor device, such heat is quickly released to the outside of the device. A substrate to be used is required.

However, since conventionally used alumina materials for various insulating substrates and semiconductor element housing packages have a low thermal conductivity of about 20 W / mK, nitriding having a high thermal conductivity as an alternative thereto. Aluminum has begun to be noticed.

Originally, aluminum nitride has a high theoretical thermal conductivity of 320 W / mK in a single crystal, and as a result of progress in research and development, recently, an aluminum nitride sintered body exceeding 200 W / mK has also been obtained. There is.

As a method of manufacturing such an aluminum nitride sintered body, there has been a method of adding a sintering aid such as a rare earth compound or an alkaline earth compound and firing it at a high temperature of 1800 ° C. or higher.

However, the above manufacturing method has a drawback that the manufacturing cost becomes considerably high in consideration of the wear of the jig used for the baking, the structure of the baking furnace, and the running cost.

Therefore, in order to eliminate such drawbacks and reduce the manufacturing cost, there has been proposed a method in which a rare earth compound and an alkaline earth compound are simultaneously added as a sintering aid and the mixture is fired at 1600 to 1700 ° C ( Japanese Patent Examination 6-49613
(See Japanese Patent Publication No. 7-17454).

[0008]

However, when a product such as a package is manufactured by using the aluminum nitride sintered body obtained by simultaneously adding the rare earth compound and the alkaline earth compound, it is used in the plating step. However, there is a problem in that the aluminum nitride sintered body is deteriorated by acid or alkaline chemicals, and particularly in the case of alkaline chemicals, the aluminum nitride itself is dissolved so that deterioration is remarkable.

[0009] Further, when attempting to improve the chemical resistance of the aluminum nitride sintered body, there arises a problem that the thermal conductivity is lowered, and at present, the sintering is performed at a temperature of 1700 ° C or lower. However, there is a problem in that an aluminum nitride sintered body that is not deteriorated by chemicals such as acids and alkalis and that exhibits a high thermal conductivity of at least 70 W / mK has not been obtained.

[0010]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above problems, and an object thereof is aluminum nitride excellent in chemical resistance to acids and alkalis while keeping manufacturing cost low and maintaining high thermal conductivity. The object is to provide a high quality sintered body and a manufacturing method thereof.

[0011]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies on the above problems, and as a result, added both RE and R as sintering aids, and also added SiO ₂ and MgO.
Is added and calcined at a temperature of 1700 ° C. or lower to crystallize a YAG type crystal as a main grain boundary phase, thereby significantly improving chemical resistance to acids and alkalis while maintaining high thermal conductivity. It has been found that a sintered body and a manufacturing method thereof can be obtained.

That is, the aluminum nitride sintered body of the present invention contains AlN as a main component, contains at least both RE and R in a total amount of 0.5 to 20.0 wt% in terms of oxide, and further contains SiO ₂ And MgO in a total amount of 0.1 to 3.0% by weight, and the main crystal phase of the grain boundary phase is a YAG type crystal.

Further, as a method for producing such an aluminum nitride sintered body, both RE and R, which are main sintering aids for AlN, in total of 0.5 to 20.
0% by weight, and SiO ₂ and MgO in total of 0.1 to 3.
0% by weight, and a mixed powder prepared so that the molar ratio of Al ₂ O ₃ to RE ₂ O ₃ (Al ₂ O ₃ / RE ₂ O ₃ ) was 1.7 to 20.0 was molded and molded at 1700 ° C. It is characterized in that it is fired at the following temperature to crystallize a YAG type crystal as a main crystal phase of a grain boundary of the aluminum nitride sintered body.

[0014]

According to the aluminum nitride sintered body and the method for producing the same of the present invention, the sintering aid RE reacts with the impurity oxygen contained in the aluminum nitride raw material to form a liquid phase, thereby sintering. In addition to promoting YAG, YA during sintering
It is possible to increase the thermal conductivity of the sintered body by generating a crystal phase such as P or YAM and reducing the oxygen dissolved in the aluminum nitride particles constituting the sintered body.

The R also reacts with the impurity oxygen contained in the aluminum nitride raw material to form a liquid phase at a lower temperature than RE, accelerates the sintering, and crystallizes into an aluminate during the sintering. It is possible to reduce the amount of oxygen that is solid-solved in the aluminum nitride particles that form the sintered body and to achieve high thermal conductivity.

In the present invention, further addition of addition of SiO _2, MgO, entire Al ₂ O based on the amount of Al ₂ O _3, which is converted from the impurity oxygen amount contained in the aluminum nitride raw material
_The amount of ₃ is adjusted, and SiO ₂ , MgO, and Al ₂ O ₃ each have excellent chemical resistance, and Al ₂ O ₃ reacts with RE to stabilize the grain boundary crystal phase to the YAG type and to improve alkali resistance. Will be improved.

The addition of SiO ₂ and MgO lowers the liquidus formation temperature and improves the sinterability at low temperatures. When Al ₂ O ₃ is further added, it reacts with the sintering aid. A liquid phase is generated to further promote sintering.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The aluminum nitride sintered body of the present invention and the method for producing the same will be described in detail below.

First, as the aluminum nitride raw material for producing the aluminum nitride sintered body of the present invention, it is desirable that the amount of impurity oxygen is 0.5 to 3.0% by weight.

The RE added to the aluminum nitride raw material powder includes Y, La, Ce, Pr, Nd, Pm and S.
m, Eu, Gd, Tb, Dy, Ho, Er, Tm, Y
Any element such as b and Lu can be preferably used, and any element such as Ca, Ba and Sr can be suitably used as R.

The amount of RE or R added is less than 0.5% by weight or 2 or more in terms of oxide of one or more of them.
If it exceeds 0.0% by weight, the chemical resistance is poor and the thermal conductivity is as low as 70 W / mK or less.

Therefore, the amount of both RE and R is specified to be 0.5 to 20.0% by weight in terms of oxide, and RE ₂
O ₃ + (Ca, Ba, Sr) O is 1.0 to 20.0% by weight, and specifically, RE is 0.5 to 15% in terms of oxide.
0% by weight, R is preferably 0.05 to 5.0% by weight, more preferably RE is 3.0 to 10.0% by weight, and R is 0.
It is in the range of 2 to 1.0% by weight.

On the other hand, the total amount of SiO ₂ and MgO is 0.
If it is less than 1% by weight, the chemical resistance is poor, and if it exceeds 3.0% by weight, the thermal conductivity is lowered. Therefore, the total amount is specified to be 0.1 to 3.0% by weight, more preferably 0.
It becomes 2 to 1.0% by weight.

Al ₂ O ₃ is mainly YA in the grain boundary phase.
In order to crystallize the G-type crystal phase, the amount of RE ₂ O _{3 and the} amount of Al ₂ O ₃ converted from the amount of impurity oxygen in the aluminum nitride raw material powder and A added as necessary
It must be determined by the ratio of the amount of 1 ₂ O ₃ and the sum thereof, and theoretically, the molar ratio (Al ₂ O ₃ / RE ₂ O ₃ ) is 1.67.
However, to obtain a stable YAG type crystal phase, Al
_Since it is necessary to make the composition rich in ₂ O _3, it is desirable that the molar ratio is in the range of 1.7 to 20.0.

The above-mentioned forming raw materials prepared by mixing and mixing a predetermined amount of aluminum nitride raw material powder and the respective sintering aids, and adding an organic binder and a solvent to the mixed powder are used. For example, after a molded body is obtained by a molding method such as a press molding method, a CIP molding method, a tape molding method, an extrusion molding method, or an injection molding method, the molded body is kept at a predetermined temperature in a non-oxidizing atmosphere. 1550 after debinding
A sintered body can be obtained by firing at a temperature of ˜1700 ° C.

[0026]

The present invention will be described in detail below based on an embodiment.

The average particle size is 1.9 μm and the oxygen content is 0.98.
% AlN raw material powder produced by the reduction nitriding method.
In addition to adding and mixing a predetermined amount of the sintering additive shown in (1), in addition to the oxygen amount based on the analysis of each sintering additive, the amount of Al ₂ O ₃ converted from the amount of oxidized impurities in the AlN raw material, and if necessary, The amount of Al ₂ O ₃ added as the total amount of Al ₂ O ₃ is adjusted to adjust the amount of oxygen, paraffin wax is added to the mixed powder as a binder for molding using isopropyl alcohol as a solvent, and the mixture is kneaded and dried, and then molded through a sieve. To obtain granules for
The granules were pressed with a mold at a molding pressure of 1 ton / cm ² .
A disk having a diameter of 12 mm and a thickness of 5 mm was formed.

[0028]

[Table 1]

The molded body thus obtained was debindered at a predetermined temperature and then fired in a nitrogen stream at a temperature of 1650 ° C. for 3 hours to produce an aluminum nitride sintered body, which was used as a sample for evaluation.

Using the above-mentioned sample for evaluation, first, the density of the aluminum nitride sintered body was measured by the Archimedes method,
The ratio (%) to the theoretical density was calculated. Then, the main crystal phase of the grain boundary phase is identified by X-ray diffraction method, and
The thermal conductivity was measured by the laser flash method.

The chemical resistance is 4 as an acidic chemical.
6% HF solution, 4N N as alkaline chemical
Using an aOH solution, each solution was kept at 25 ° C. and the sample was immersed in the solution for 100 hours, and then the weight change of the sample before and after the immersion was measured, and the appearance of the sample was visually and microscopically observed. Good if no change is observed,
Those with a change were judged to be defective.

[0032]

[Table 2]

As is clear from the results of Table 2, the sample numbers 9, 13, and 23, which mainly crystallize the YAP type crystal phase and the YAM type crystal phase outside the claims of the present invention at the grain boundaries,
The molar ratio (Al ₂ O ₃ / RE ₂ O ₃ ) was less than 1.7, the chemical resistance was poor, the weight reduction was remarkable, and the discoloration was remarkable.

Further, even if the crystal phase of the grain boundary is mainly of YAG type, Sample Nos. 1, 7, 16, 21, and 22 having a composition outside the scope of the claims of the present invention have insufficient densification, or It is considered that the grain boundary phase with low thermal conductivity increases, but both have poor chemical resistance and thermal conductivity of 67 W.
/ MK or less, and Sample No. 22 has a thermal conductivity of 85 W / mK, but it has insufficient chemical resistance and is not practical.

On the other hand, it is understood that in all of the present invention, the crystal phase of the grain boundary is mainly of YAG type, the chemical resistance is excellent, and the thermal conductivity is maintained at 80 W / mK or more.

[0036]

As described above in detail, according to the aluminum nitride-based sintered body of the present invention and the method for producing the same, both RE and R as a main sintering aid for AlN, and SiO ₂ are further added.
Since a powder obtained by adding and mixing MgO, MgO, and Al ₂ O ₃ was molded and fired at a temperature of 1700 ° C. or lower, YAG type crystals were crystallized as a main crystal phase of grain boundaries of the aluminum nitride sintered body 70W / m denser at lower temperature than before
It is possible to obtain an aluminum nitride-based sintered body that maintains a high thermal conductivity of K or higher and that has excellent chemical resistance to acids and alkalis.

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Akihiko Nishimoto 1-4 Yamashita-cho, Kokubun-shi, Kagoshima Inside Kyocera Research Institute (56) Reference JP-A-8-157264 (JP, A) JP-A-8 -157261 (JP, A) JP 63-277568 (JP, A) JP 6-329474 (JP, A) JP 8-81267 (JP, A) (58) Fields investigated (Int.Cl) . ⁷ , DB name) C04B 35/581

Claims (2)

(57) [Claims] 1. A main component is aluminum nitride (AlN), and a total of at least rare earth element (RE) and alkaline earth metal (R) is 0.5 to 20.0% by weight in terms of oxide,
Silica (SiO ₂ ) and magnesia (MgO) are added in a total of 0.
1 to 3.0% by weight, and the main grain boundary phase is YA
An aluminum nitride-based sintered body characterized by comprising a G-type crystal. 2. A total of 0.5 to 20.0% by weight of rare earth element (RE) and alkaline earth metal (R) as a sintering aid in terms of oxide in aluminum nitride (AlN) and silica (S).
iO ₂ ) and magnesia (MgO) total 0.1-3.0
% By weight, and alumina (Al ₂ O ₃ ) in molar ratio (Al ₂ O ₃ ) to oxide (RE ₂ O ₃ ) of the rare earth element (RE).
₂ O ₃ / RE ₂ O ₃ ) was molded into a mixed powder having a particle size of 1.7 to 20.0, and the molded body was molded at 1700 ° C.
A method for producing an aluminum nitride-based sintered body, which comprises firing at a temperature below to crystallize a YAG type crystal as a main grain boundary phase.