JPS6369764A - Aluminum nitride sintered body and manufacture - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Objective of the Invention] (Industrial Application Field) The present invention relates to an aluminum nitride (A I N) sintered body and a method for manufacturing the same, and more specifically, a sintered body with a thermal conductivity of 100.
The present invention relates to an AIN sintered body that is effective as a material for semiconductor heat sinks because it has a high thermal conductivity of W/m11 or more, and a method for manufacturing the same.

(Prior art) A-shaped N sintered bodies have excellent insulation, corrosion resistance, and thermal shock resistance, and have high high-temperature strength and high thermal conductivity, so they are used in various structural materials and various electronic and electrical parts. In recent years, it has been attracting attention as a material for heat sinks for semiconductors, replacing alumina (CAnzOs), which does not have sufficient heat dissipation properties, and beryllia (B e O), which is difficult to handle due to its toxicity.

Such an AIN sintered body is manufactured as follows. First, for example, yttrium oxide (Y
After blending a predetermined amount of a sintering aid such as 203), adding a binder and molding, heating in a nitrogen gas stream,
After removing the binder, sintering is performed by heating at a predetermined sintering temperature for a predetermined time. Even if the AIN sintered body thus obtained has a high thermal conductivity, if the amount of 02 in the raw material is 3% by weight or more, the thermal conductivity is about 70 W/m-.

By the way, AfLNa! When the body is used as a heat sink for semiconductors, a large sintered AIN plate is cut into predetermined dimensions and used. Therefore, in order to manufacture an AIN heat sink with excellent heat dissipation, it is necessary to use Au, which has high thermal conductivity.
It is necessary to manufacture the N sintered body (plate) as the material.

(Problem to be solved by the invention) When using an AuN sintered body as a heat sink, this A
The higher the thermal conductivity of the uN sintered body, the better.

Therefore, the present inventors have made extensive efforts to manufacture AuN sintered bodies with high thermal conductivity, but as the thermal conductivity increases, the AuN sintered bodies become more transparent, and as a result,
It has been discovered that an unexpected problem arises.

That is, the fact that network-like "segregation lines" that were not visible until now are generated in the AuN sintered body is now visible because the entire body becomes translucent. this"
Although the structure and generation mechanism of "segregation lines" have not yet been elucidated, they are some sort of segregation. Its characteristics are also different from other areas.

In other words, it can be said that the various properties of the obtained AuN sintered body vary depending on the location even in the same sintered body. This fact is due to the fact that Au has high translucency and high thermal conductivity.
This knowledge was discovered because we were able to manufacture a N sintered body.

Therefore, such segregated substances run vertically and horizontally in a striped manner
When a heat dissipation board is cut from a N sintered body, the thermal conductivity of the board will be different between the board that contains this "segregation line" and the board that does not, so they cannot be used under the same design standard. It disappears.

The present invention solves the above problems and has a thermal conductivity of 100.
It is an object of the present invention to provide an AuN sintered body having a W/m- or more and having less variation in properties since the above-mentioned "segregation line" does not exist, and a method for manufacturing the same.

[Structure of the Invention] (Means for Solving the Problems) As a result of extensive research to achieve the above object, the present inventors found that when an AuN green compact is sintered under the conditions described below, this segregation The present invention was completed based on the discovery that substances do not dissolve in solid solution to form segregated substances.

That is, the aluminum nitride sintered body of the present invention is characterized by having a thermal conductivity of 1100 WZ or higher and containing segregated substances as a solid solution, and the method for manufacturing the same includes press-molding aluminum nitride powder. The method for producing an aluminum nitride sintered body by sintering the obtained green compact is characterized in that atmospheric pressure is increased while the sintering temperature is maintained.

The A-N sintered body of the present invention has a thermal conductivity of 100 W/mφ or more, and has a uniform structure in which segregated substances are dissolved in solid solution. In this way, the thermal conductivity of the AuN sintered body is reduced to 1
In order to achieve 00 W/m or more, the raw material AuN
The AM/N molar ratio of the powder approaches 1, and the contained F
e.

It is preferable to reduce impurities such as Si, C, Mg, Ca, and oxygen. In particular, it is important that the oxygen content of the A-mon powder is 2% by weight or less.

Preferably it is 1 to 2% by weight.

Next, a method for manufacturing an AuN sintered body of the present invention will be described. First, as the AuN powder, one containing 2% by weight or less of oxygen is prepared in consideration of thermal conductivity as described above.
A predetermined amount of sintering aid is added to this AuN powder, and then mixed using a ball mill or the like. The sintering aid used at this time may be any commonly used one, such as yttrium oxide (Y2O2), and the amount added is 1 to 5% by weight, preferably 3-5
Weight%.

Next, a binder such as a commonly used paraffin binder is added to this mixed powder, followed by kneading, granulation,
The particles are sized and pressure molded.

After placing the obtained AuN powder compact in a furnace, N was heated at normal pressure.
The binder is removed by raising the temperature in an atmosphere such as 2.

Furthermore, the Aj2N powder compact is transferred to another sintering furnace and heated to the optimum sintering temperature in an atmosphere such as N2. The temperature increase rate at this time is 100 to 500"C/hr, preferably 100 to 100"C/hr.When the optimum sintering temperature is reached, this temperature is maintained and the atmosphere in the furnace is pressurized at the same time. Sinter the LN compact while maintaining the state A!; If the atmospheric pressure at this time exceeds 5 kg/cm, the segregation will disappear and the sintered compact will be uniform in appearance, and if the atmospheric pressure is less than 2 kg/cm If there is, segregation will precipitate, resulting in a sintered body that is non-uniform in appearance, so it is set at 2 to 9 Kg/cm.Preferably 4 to 5 Kg/cm.
It is d. Sintering time is 0.5-4 hours, preferably 1-4 hours.
It is 3 hours. Thereafter, the atmosphere is brought to normal pressure and cooled.

The temperature decreasing rate at this time is not particularly limited, but is usually 100%.
~500°C/hr, preferably 200-300°C/h
It is r.

(Example) Example A raw material was prepared by adding 3% by weight of Y2O3 as a sintering aid to AN powder containing 1.0% by weight of oxygen as an impurity, and grinding and mixing using a ball mill. Then,
After adding 12% by weight of a paraffin binder to this raw material and granulating it, it was press-molded at a pressure of 800 kg/d to form a 35.0X35, OXI Om.
It was made into a green compact of m. This green compact was heated to 700'O in a N2 atmosphere at a heating rate of 100°C/min to remove the binder. Furthermore, it was transferred to another sintering furnace and the temperature increase rate was 150
After increasing the temperature at a rate of .degree. C./min, sintering was carried out for 2 hours at 1770.degree. C. in a N2 atmosphere while maintaining the atmospheric pressure at 6 kg/cm. After that, the atmospheric pressure is returned to normal pressure and the temperature decrease rate is 35.
Cooled at 0°C/min.

Obtained 29. lX29. IXo, cut the 8mm A pattern N sintered body 29. lX29. Four IXO, 2 mm heat sinks for semiconductors were obtained. Among these, there are 4 heat sinks for semiconductors that do not contain even a part of segregated substances, and the product yield is 100%.
Met. In addition, the obtained heat sink was ground into a disk with a diameter of 10 mm and a thickness of 2 mm, and this was used as a test piece to measure the thermal conductivity by the laser flash method.The average of the results was 130 W/m. .

Comparative Example 1 An AIN sintered body was manufactured in the same manner as in the example except that the AIN green compact was sintered while the atmospheric pressure remained at normal pressure, and a heat sink for a semiconductor was obtained.

Among these, heat sinks for semiconductors that do not contain even a part of segregated substances are
There were 0 out of 4, and the product yield was 0%. Also,
When the thermal conductivity was measured in the same manner as in the example, it was L30W.
/m・k.

Comparative Example 2 An AuN sintered pair was produced in the same manner as in the example except that AJJN powder with an oxygen content of 3% by weight was used,
A heat sink for semiconductors was obtained. Among these, 4 out of 10 heat sinks for semiconductors did not contain even a part of segregated substances, and the product yield was 40%. Further, when the thermal conductivity was measured in the same manner as in the example, it was OOW/m·k.

[Effects of the Invention] As is clear from the above description, the AIN sintered body of the present invention has an excellent high thermal conductivity, and is uniform in that segregated substances are dissolved in solid solution. Even if it is cut into heat sinks for semiconductors, the yield of the product will not decrease. Therefore, its industrial value is extremely high.
It is particularly useful as a material for heat sinks for semiconductors.

Claims (1)

[Claims] 1. An aluminum nitride sintered body characterized by having a thermal conductivity of 100 W/m·k or more and containing segregated substances in solid solution. 2. A method for producing an aluminum nitride sintered body by sintering a green compact obtained by pressure-molding aluminum nitride powder, characterized in that the atmospheric pressure is increased while the sintering temperature is maintained. A method for producing an aluminum nitride sintered body. 3. The method for producing an aluminum nitride sintered body according to claim 2, wherein the aluminum nitride powder has an oxygen content of 2% by weight or less.