JPS6163596A - Installation for production of single crystal of compound semiconductor - Google Patents

Abstract

PURPOSE:The part for controlling the shape of a single crystal is made of sintered aluminum nitride to prevent the part from being corroded with the starting materials for the crystal and the melt sealant whereby dimensional stability and the quality of the crystals are improved. CONSTITUTION:The unit for production of single crystals of compound semiconductors is composed of a high-pressure vessel 1, a crucible 2 containing melted starting materials 7 and liquid sealant, a part for controlling the shape of the crystal which is set on the interface between both melts 7 and 8 and has an opening 13 and a pulling-up unit 9 for the crystal. The part 12 is constituted of sintered aluminum nitride.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an apparatus for manufacturing a compound semiconductor single crystal using the LEC method.

[Technical background of the invention and its problems] Conventionally, GaAs, In-P, Ga
The LEC method is known as a method for manufacturing compound semiconductor single crystals with high decomposition pressure at the melting point of -P, etc.

To explain this method using Fig. 2, first, the high pressure vessel 1
A crucible holder disposed within the crucible holder mounts the crucible 2 containing the crystal raw material and a sealant such as 8203 on the table 3.4.5.

Next, the crucible 2 is heated by a heating element 6 coaxially surrounding the crucible 2, and the crystal raw material and the sealant are heated and melted.

At this time, the crystal raw material melt 7 and the sealant melt 8 are in the 211 state due to the density difference, and the crystal raw material melt 7 (
The density of the melt is about 5.7 (+/C!, In-
About 5.0Q/cd for P, about 4.4Q/cd for Ga-P
cd> is a sealant melt 8 with a small density (melt density is B2O
3 (approximately 1.5'l/cj), decomposition and evaporation of the crystal raw material melt 7 can be suppressed.

Further, at this time, by heating the inside of the high-pressure container 1 with an inert gas, vaporization of the crystal raw material melt 7 is suppressed.

In this state, the seed crystal 1 attached to the tip of the crystal pulling shaft 9
0 passes through the sealant melt 8 and comes into contact with the crystal raw material melt 7, and then the pulling shaft 9 is rotated! The single crystal 11 is removed by pulling it up.

As described above, the LEC method has the advantage of being able to pull compound semiconductor single crystals using relatively intermediate equipment, but on the other hand, defects often occur in the single crystals grown by this method, and crystal The disadvantage is that it is difficult to accurately control the cross-sectional shape of the

This is because the atmosphere in which the crystals are formed is under high pressure, so there is severe heat convection, which causes heat dissipation and temperature distribution at the melt interface to become uneven, increasing internal strain within the crystal. The crystal raw material melt diffuses into the melt, and the crystal raw material Fa
? l! This is believed to be because ffi evaporates through the sealant melt, clouding the monitoring window attached to the device and interfering with single crystal shape control.

For this reason, a single crystal shape control member having a frontage for regulating the shape of the single crystal is floated in the crystal raw material melt, and the single crystal is pulled up through this frontage. When this single crystal shape control member is used, the shape control member covers the crystal raw material melt and prevents heat radiation from the crystal raw material melt, resulting in a stable thermal state near the solid-liquid interface and a less distorted single crystal. can be obtained.

This single-crystal shape control member is required to have excellent high-temperature corrosion resistance and mechanical strength, and is usually made of materials such as silica, graphite, and silicon nitride.

However, with these materials, the crystal raw material melt is often contaminated, making it difficult to meet the recent demands for higher purity and higher quality, especially for Qa AS single crystals.

[Purpose of the Invention] The present invention has been made to solve these difficulties,
Provides compound semiconductor single crystal manufacturing equipment that can manufacture high purity, high quality single crystals using single crystal shape control members with excellent high temperature corrosion resistance and mechanical strength without contaminating the crystal raw material melt. The purpose is to

[Summary of the Invention] That is, the compound semiconductor single crystal manufacturing apparatus of the present invention comprises: a high-pressure container; a crucible disposed in the high-pressure container to accommodate a material melt and a sealant melt; a shape control member for a pulled single crystal having a frontage in the center disposed at the interface between the crystal raw material melt and the sealant melt; a heating element that surrounds and heats the crucible; and a heating element that can be raised and lowered above the crucible. In the compound semiconductor single crystal manufacturing apparatus, the single crystal shape control member 11 is made of an aluminum nitride-based sintered body.

The shape control member 11 in the present invention has a specific gravity smaller than the specific gravity of the crystal raw material melt and larger than the specific gravity of the sealant melt, and is manufactured, for example, as follows.

That is, an oxide of a rare earth element such as yttrium oxide or an oxide of an alkaline earth metal element such as calcium oxide is added to aluminum nitride as a sintering agent, and boron nitride is added to the grains as necessary and mixed. After that, a binder such as paraffin is added and molded into a predetermined shape.

The shape of the shape fli control member is a hollow truncated cone-like shape having a center portion corresponding to the required cross-sectional shape of a single crystal, and having a size that fits in a crucible. After molding, it is degreased and then heated at 1700-1900℃ in an inert atmosphere.
By heating and firing, it is possible to obtain a single-crystal shape control member made of an aluminum nitride-based sintered body that is uniformly [5].

[Embodiments of the invention] Next, examples of the present invention will be described.

Example: Aluminum nitride was mixed with 3% by weight of yttrium oxide and formed into a shape similar to 311 hollow circles with open tops and bottoms as shown in Fig. 2, and then heated at 1850'C in a nitrogen atmosphere.
The single-crystal shape control member 12 was manufactured by sintering by the pressureless sintering method under the conditions of X2 hours.

Next, this single crystal shape control member 12 is shown in FIG.
As shown in FIG.
The crucible 2 was heated by the heating element 6, and the shape control member 12 was positioned at the interface between the crystal raw material melt 7 of Qa and AS and the sealant melt 8.

In this state, the seed crystal 1 attached to the tip of the crystal pulling shaft 9
0 to g40 part 1 of sealant melt 8 and shape control member 12
3 to contact the crystal raw material melt 7, and then
By pulling up while rotating the pulling shaft 9, a GaΔS single crystal 11 having a cross-sectional shape corresponding to the opening 13 of the shape control member 12 was obtained. Note that the reference numeral 14 in FIG. 1 indicates a heat retaining member.

The impurities in the Qa-AS single crystal prepared in this way were less than IXllXlo-15'', which was significantly reduced compared to when a shape control member made of silicon nitride was used. As a result of the stable thermal conditions in the vicinity, the single crystal was of good quality with little distortion.

[Effects of the Invention] As explained above, by using the apparatus of the present invention, there is no contamination of the crystal raw material melt, and a highly pure compound semiconductor single crystal can be obtained. In addition, this single-crystal shape control member made of aluminum nitride-based sintered material has excellent high-temperature corrosion resistance and thermal shock resistance, so it is less likely to be eroded by the crystal raw material melt or the sealant melt, as well as the accompanying deterioration and deformation. , a compound semiconductor single crystal with good dimensional stability and high quality can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view schematically showing an embodiment of a compound crystal semiconductor manufacturing apparatus using the LEC method, and FIG. 2 is a perspective view of a single crystal shape control member used in the apparatus of the embodiment of the present invention.

Claims (1)

[Claims] (1) A high-pressure container, a crucible disposed in the high-pressure container and containing a crystal raw material melt and a sealant melt, and a crucible disposed at an interface between the crystal raw material melt and the sealant melt. Manufacture of a compound semiconductor single crystal, comprising: a shape control member for pulling a single crystal having an opening in the center; a heating element that surrounds and heats the crucible; and a crystal pulling device disposed above the crucible so as to be movable up and down. An apparatus for manufacturing a compound semiconductor single crystal, characterized in that the single crystal shape control member is made of an aluminum nitride-based sintered body.