JPS6385055A - High density aluminum nitirde normal pressure sintered body - 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] "Industrial application field" The present invention relates to a high-density pressureless sintered aluminum nitride body.

"Prior art" Aluminum nitride (AIM) sintered bodies have high bending strength at room temperature and high temperature (more than 30 kg/rmm2 at room temperature,
It has a high thermal conductivity (more than 30 W/m/m at room temperature) and is used as a heat-resistant material, thermal shock-resistant material, and heat dissipation material.

AIM is a compound of AI, which belongs to the m group of the periodic table, and N, which belongs to the V group, and its sintered body has high strength and high thermal conductivity.
It is desired to make parts for manufacturing equipment for group compound semiconductors using this AIM sintered body.

Conventionally known methods for producing AIM sintered bodies include reaction sintering, hot press sintering, and pressureless sintering.

Among these, in the reaction sintering method, the sintered body obtained is porous and only a low-density product can be obtained, and unreacted metal often remains inside the sintered body, resulting in poor heat resistance and high temperature strength. Run short.

As is well known, the hot press sintering method involves applying mechanical pressure in a uniaxial direction to a sintered object housed in a mold and sintering it at high temperature. Although it is possible to obtain AIN sintered bodies, it has the drawbacks of not being able to produce complex-shaped or large-shaped products, resulting in low productivity and high costs. ・The pressureless sintering method is a process in which the sintered body is formed into an arbitrary shape in advance. The body is sintered at high temperature in an atmosphere around atmospheric pressure without applying any mechanical pressure.This method allows for easy mass production and can produce products with complex shapes and large shapes. Can be manufactured. However, according to the conventional technology, in order to obtain a high-density AIN sintered body by this pressureless sintering method, it is essential to add a sintering aid, and this sintering aid includes alkaline earth elements and rare earth elements. compounds were used.

However, such sintering aids generally have a relatively high vapor pressure at high temperatures, and the resulting sintered body has the disadvantage that the surface portion thereof is not sufficiently dense or is deformed depending on the shape. Furthermore, for example, even if the crucible for pulling the m-v group compound semiconductor single crystal and the shielding tube for the pulling device are made of such an AIN pressureless sintered body, the obtained m-v group compound semiconductor single crystal will have sufficient physical properties. It wasn't.

``Object of the Invention'' The present invention aims to eliminate the above-mentioned drawbacks of the prior art. That is, the present invention allows large-sized products and complex-shaped products to be easily obtained, and It is an object of the present invention to provide a novel high-density A1% sintered body that can be suitably used as a member for a V-group compound semiconductor manufacturing device.

"Structure of the Invention" The present invention is characterized in that the total amount of metal excluding aluminum is 11,000
pp or less and a relative density of 98% or more.

In the present invention, the total amount of metal impurities in the All sintered body, that is, metals excluding aluminum (AI), is 11,000.
It is important that it is less than pp. When manufacturing parts for m-v group compound semiconductors are formed using an AIN sintered body containing such metal impurities in a total amount greater than 1000 pp layer, these metal impurities are mixed into the m-v group compound semiconductors, and as a result, this Semiconductor properties deteriorate. In other words, when metal impurities are mixed into a ■-V group compound semiconductor, they increase lattice defects such as dislocations in the semiconductor crystal, which lowers the mobility of electrons. The speed will be slower.

Metal impurities whose content should be kept at 11,000 pp or less in an All sintered body generally exist as metal compounds such as metal oxides or metal nitrides rather than as simple metals. In the present invention, regardless of which of these forms it is, the total amount in terms of metal is 1000 ppm or less, more preferably 500 ppm or less, and even more preferably 200 ppm.
It is necessary that the following are met.

By the way, when we examined the influence of metal impurities present in All sintered bodies for each metal type, we found that Si, Fe, Cu, Mg
It has been found that the presence of the compound semiconductor greatly deteriorates the physical properties of the resulting m-v group compound semiconductor.

However, the content of Tesi, Fe, Cu, and Mg in the All sintered body is 20 ppm or less, especially 10 ppm or less.
It is preferable to set it to p+s or less, and it is preferable that metal species other than these are set to below the toopp layer, and the C (carbon) content in the All sintered body is also 100
It is preferable that the content be less than OPPII, more preferably less than 500 pp-, in order to improve the physical properties of the resulting ■-V group compound semiconductor.

The reason for excluding AI is that since AI is an element belonging to group 1, even if a small amount is mixed into a group 2-v compound semiconductor such as GaAg, it does not have a great effect on the physical properties of the semiconductor.

Furthermore, the AIN sintered body of the present invention has a relative density (theoretical density is 10
(relative value when taken as 0%) is required to be 98% or more. In an AIN sintered body with a lower density than this, the surface layer in particular tends to become porous, rich in Al2O3, Al0N, etc., which reduces bending strength and thermal conductivity, and also reduces Ga
Reactions with various high-temperature gases including Ag occur, which is undesirable, and in the case of a thin AIM sintered body, gases such as GaAs also permeate and leak, which is undesirable.

The AIN sintered body of the present invention is manufactured by a pressureless sintering method. According to this method, products with complex shapes and large shapes can be manufactured, mass production is easy, and costs can be reduced. Here, pressureless sintering typically means sintering under pressure around atmospheric pressure, and a non-oxidizing atmosphere, particularly a nitrogen gas atmosphere, is employed as the atmospheric gas. However, the AIN of the present invention
Pressureless sintered bodies include those sintered under a non-oxidizing uniform pressure atmosphere of 0.5 to 50 atm, and the pressureless sintered body once obtained is further re-sintered under 10 to 3000 atm. Sintering is preferable because a sintered body with even higher density and higher strength can be obtained.

The AIM pressureless sintered body of the present invention is typically manufactured as follows.

First, the content of metal impurities as AIM raw powder is 100%.
Adopt high purity products with 0 pp- or less. If the metal impurities in the obtained sintered body are 500 ppm or 200 ppm or less, and the content of Si, Fe, Cu, or Mg in the sintered body is 20 ppm or less, each raw material A is used.
It goes without saying that an IN powder that satisfies these conditions should be used as the IN powder.

The employment of such high-purity AIN raw material powder is also advantageous from the viewpoint of obtaining a high-density sintered body. In other words, if an AIN raw material powder with a metal impurity content of more than 11,000 pp is used, it is difficult to obtain a sintered body with a relative density of 98% or more without a sintering aid. It is thought that this decreases the sinterability.

Sintering aids such as compounds of alkaline earth elements and rare earth elements, which are commonly used in obtaining AIN pressureless sintered bodies, are not added in the production of the sintered bodies of the present invention.

The high-purity AIM fine powder, an organic polymer binder, and a plasticizer are blended, mixed and pulverized using a ball mill, etc., and then dried, granulated, and classified, and then subjected to the usual molding method and cold isostatic pressing method. Shaped by etc. The obtained molded body is housed in a carbon container whose inner surface is coated with AI gold metal and/or A1 compound (excluding AIM), particularly a carbon container whose inner surface is coated with AI gold metal, and Sintering is carried out at 1,800 to 2,000°C under a nitrogen gas atmosphere of .5 to 50 atmospheres, particularly in a nitrogen gas atmosphere around atmospheric pressure.

"Examples" The present invention will be described in detail below based on Examples and Comparative Examples.

Example 1 Metal impurity content (pp) determined by elemental analysis is Si
330. Mg 110. Fe3G, Cu(10,
Ti(10, Gr(1G, Ca80, K(10),
And the total amount of metals other than AI including other metals is 800pp
After mixing, grinding, drying, granulating, and classifying fine AIN powder with a C content of 900 ppt and an appropriate amount of organic polymer and organic plasticizer according to conventional methods, the size after sintering is 200 ppt. ■, wall thickness 10m+m, height 500+im
It was molded by cold isostatic pressing into a pipe shape. This molded body was housed in a carbon covered sheath whose inner surface was coated with metal AI paste, and sintered at 1900° C. for 5 hours in an atmosphere of 1 atm of nitrogen.

The relative density of the obtained pipe-shaped AIM sintered body was 98.5%.
Further, elemental analysis of this sintered body revealed that the content of metal impurities for each metal type and as a total amount, as well as the C content, were essentially the same as those in the raw material.

Ga equipped with p-BN crucible and carbon crucible holder
In the As single crystal pulling apparatus, the pipe-shaped AI obtained above
When the M sintered body was used as a shielding tube, it could be used without any problems under the operating conditions, and the electron mobility of the pulled GaAs single crystal was as good as 4200 cm2/V/sec.

Example 2 Metal impurity-containing PM (ppm) determined by elemental analysis was found to be S
i50. Mg40. Fe 20. Gu(1,
TiclO,0r(10, Cao,K(1), and the total amount of metals other than A1 including other metals is 400p
A pipe-shaped AIN sintered body with a relative density of 99.5% was obtained in the same manner as in Example 1 using Teal AIM fine powder with a C content of 450 ppm or less. The content of metal impurities for each metal type and as a total amount, as well as the C content, were not different from those in the raw material in terms of wood quality.

When this pipe-shaped AIM sintered body was used as a shielding tube in the same GaAs single crystal pulling apparatus as in Example 1, it could be used without any problems under the usage conditions, and the pulled GaAs
The single crystal had a good electron mobility of 4500 cm2/V/see.

Comparative Example 1 The metal impurity content (ppm) determined by elemental analysis was
1200. Mg 240. Fe 1150. Cu5.
Ti 40. Or 20. Ca145, K (l,
And the total amount of metals other than AI including other metals is 3000p
When sintering was carried out in the same manner as in Example 1 using All fine powder having a particle size of pm or less, a pipe-shaped AIM sintered body with a relative density of 80% was obtained. The content of metal impurities for each metal and as a total amount was essentially unchanged from that in the raw material.

When this pipe-shaped AIM sintered body was used as a shielding tube to prepare a GaAs single crystal in the same manner as in Example 1, the electron mobility of the pulled GaAg single crystal was 2100 cm2.
/V/sea, which was unsatisfactory. The cause of this was thought to be the decomposition and evaporation of metal impurities in the shield tube and the leakage of gas from the shield tube.

Comparative example 2 Metal impurity content (ppm) by elemental analysis.

Si510. Mg90. Fe 500. Cu 3.
Ti 20. Cr10. Ca80, K (1, and the total amount of metals other than AI including other metals is 1500pp
When sintering was performed in the same manner as in Example 1 using All fine powder having a particle size of less than m, a pipe-shaped AIM sintered body with a relative density of 95% was obtained. The content of metal impurities for each metal and as a total amount was essentially unchanged from that in the raw material.

When this pipe-shaped AIN sintered body was used as a shielding tube in the same GaAs single crystal pulling apparatus as in Example 1, the electron mobility of the pulled GaAs single crystal was 21,300 c 2/V/sea, which was unsatisfactory. there were.

Example 3 The metal impurity content (ppm) determined by elemental analysis was
15. Mg 12. Fe(10,Cu<1.Ti(
1G, 0r(io, ca 80.Nikul), the total amount of metals other than AI including other metals is less than 10ppm, and the C content is 150pp■, and Example 1 except that the shape after sintering was a crucible with a head outer diameter of 100 mm, a bottom outer diameter of 90 m5+, a height of 100 layers, and a wall thickness of 5 layers.
In the same manner as above, a crucible-shaped AIM sintered body having a relative density of 89.8% was obtained. The content of metal impurities for each metal and as mu, as well as the C content, was essentially unchanged from that in the raw material.

GaA with carbon crucible holder and AIN shielding tube
s In the single crystal pulling apparatus, the crucible-shaped AIM obtained above is
When the sintered body was used as a crucible for melting GaAs, it could be used without any problems under the usage conditions, and the electron mobility of the pulled GaAj single crystal was 4800c2/V/s.
It was good with ea.

Comparative Example 3 A crucible-shaped AI with a relative density of 38.8% was prepared in the same manner as in Example 3, except that 1 part by weight of calcium carbonate was added as a sintering aid to 89 parts by weight of the same All fine powder used in Example 3.
An M sintered body was obtained. The content of metal impurities for each metal other than Ca in the sintered body was essentially the same as that in the raw material, but approximately 4000 ppm of Ca was detected, so the total content of metal impurities was approximately 4100 ppm. Met.

When this crucible-shaped AIM sintered body was used as a GaAs melting crucible in the GaAs single crystal pulling device of Example 3, the electron mobility of the pulled GaAs single crystal was 150.
It was 0cs2/V/sec, which was unsatisfactory.

Example 4 The same All fine powder used in Example 1 was used, and the shape of the molded body was changed so that the size after sintering was 110 m in outer diameter of the head.
m, bottom outer diameter 100 layers■, height 120m layers, wall thickness 5■
A crucible-shaped AIM sintered body with a relative density of 98.5% was obtained in the same manner as in Example 1 except that it was shaped like a crucible.

The content of metal impurities for each metal and as a total amount, as well as the C content, was essentially unchanged from that in the raw material.

When the crucible-shaped AIN sintered body obtained above was used as a crucible holder in a GaAs single crystal pulling device equipped with an AIM crucible and an AIN shielding tube, it could be used without any problems under the usage conditions, and the pulled GaAs single The electron mobility of the crystal was as good as 8100c+*2/V/sec.

Comparative Example 4 A crucible-shaped A with a relative density of 90% was prepared in the same manner as in Example 4, except that the same AIM @ powder as used in Comparative Example 1 was used.
An IN sintered body was obtained. The content of metal impurities for each metal and as a total amount was essentially unchanged from that in the raw material.

When the crucible-shaped AIM sintered body obtained above was used as a crucible holder in a GaAs single crystal pulling apparatus equipped with an AIM crucible and an AIM shielding tube, the pulled GaAs
The electron mobility of the s single crystal was 5200 cm2/V/see, which was lower than that of Example 4.

"Effects of the Invention" As described above in detail, according to the present invention, an AIM pressureless sintered body with high density and high purity, which could not be obtained by conventional techniques, can be obtained. This AIM pressureless sintered body does not contain any sintering aids, and is a high-purity product that contains only a very small amount of metal impurities in addition to the sintering aids, so it is susceptible to contamination by trace metal impurities. It is extremely suitable for this purpose. Also, because of its high density, there is no gas penetration or leakage even if the thickness is thin. Therefore, the sintered body of the present invention is suitable as a component for manufacturing equipment for semiconductors, particularly m-v group compound semiconductors including GaAs. Such parts include not only parts used in parts such as shielding tubes and crucible holders where ■-V group compound semiconductor semiconductor vapor is present around them, but also parts that are melted or softened, such as crucibles. It can also be applied to parts used in parts that are in direct contact with V group compound semiconductors. In the latter case, the total amount of metals excluding AI in the sintered body of the present invention is preferably 500 ppm or less, particularly 200 ppm or less.

Furthermore, since the sintered body of the present invention does not contain a sintering aid, the sintering aid will not precipitate, infiltrate, or volatilize even during long-term use, and therefore has long-term stability in a non-oxidizing atmosphere. It can also be suitably used for required purposes.

Claims (1)

[Scope of Claims] 1. A high-density atmospheric pressure sintered body of aluminum nitride, characterized in that the total amount of metals excluding aluminum is 1000 ppm or less, and the relative density is 98% or more. 2. The high-density pressureless sintered aluminum nitride body according to claim 1, wherein the total amount of metals other than aluminum is 500 ppm or less.