JPH061686A - Production of compound semiconductor crystal - Google Patents

Abstract

PURPOSE:To stably maintain a good solid-liq. interface shape by making the volume of a seed crystal used in production equal to or larger than the volume of the shoulder of a single crystal to be produced. CONSTITUTION:A quartz boat contg. a seed crystal 1 with the volume made equal to or larger than the volume of the shoulder 2 of a single crystal to be produced and a group III material is placed on one end of a quartz glass reaction tube, a group V material is placed on the other end, and the tube is vacuum-sealed. The tube is set in a tandem electric furnace, the boat side is kept at >=1200 deg.C and the group V material side at about 600 deg.C, and GaAs is synthesized. The high-temp. side is heated while keeping the low-temp. side at a constant temp. so that the seeded part is heated to the m.p. of GaAs and the boat main body to a high temp., hence a part of the seed crystal 1 is melted, and then the whole body is solidified.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a compound semiconductor single crystal.

[0002]

2. Description of the Related Art A seed crystal used in a horizontal boat method usually has a cross-sectional area of (10-20 × 10-20) mm ² and a length of about 50 mm. It will be about 10% of that.

Taking, for example, the production of a single crystal by a temperature gradient method which is one of the horizontal boat methods, a quartz boat on which a seed crystal and a raw material polycrystal are placed is longitudinally sealed in a quartz ampoule. Single crystal production is performed in an electric furnace set to have a constant temperature gradient. This temperature gradient has a temperature distribution in which the temperature gradually increases from the seed crystal part of the quartz boat toward the rear end of the boat, and when seeding in the production of a compound semiconductor single crystal such as GaAs single crystal, the raw material side of the seed crystal is used. By setting the temperature so that the end face becomes 1238 ° C. and gradually lowering the temperature while maintaining the above-mentioned temperature gradient from the state where the GaAs melt is in contact with the seed crystal,
The melt solidifies from the seed crystal side and a GaAs single crystal grows.

In the process of growing a single crystal, the heat of solidification (heat of fusion) generated when the melt solidifies is not radiated to the vicinity of the solid-liquid interface and is rapidly radiated to the outer peripheral direction of the solid-liquid interface and to the inside of the solidified single crystal. There must be. In order to maintain the shape of the solid-liquid interface in a good state (it is preferable that the shape is convex on the melt side), it is necessary to dissipate heat in each direction in a well-balanced manner. The main heat dissipation is heat dissipation in the outer peripheral direction of the solid-liquid interface and heat dissipation into the solidified single crystal, and heat dissipation in the outer peripheral direction is almost constant in each growth process from the start to the end of single crystal growth, but solidification The heat dissipation to the inside of the single crystal that has grown
It increases as the single crystal volume increases.

[0005]

As the size of single crystals is increased, the area of the solid-liquid interface also becomes wider, and the heat of solidification, which increases accordingly, must be radiated. However, in conventional single crystal growth using a seed crystal, heat dissipation into the single crystal in the solidified small volume region immediately after the start of growth is insufficient, and the solid-liquid interface shape in this region becomes concave. It has become a problem to shut it down.

The present invention has been made in view of the above points, and an object thereof is to provide a method for producing a compound semiconductor single crystal capable of stably maintaining a good solid-liquid interface shape. is there.

[0007]

The above object is achieved by making the volume of the seed crystal used during the production equal to or more than the volume of the shoulder portion of the single crystal to be produced.

[0008]

Since the above-mentioned means is provided, the amount of heat radiated to the inside of the single crystal in the single crystal growth start region becomes large.

[0009]

EXAMPLES Next, the present invention will be specifically described by way of examples.

[Embodiment 1] FIG. 1 shows an embodiment of the present invention. In the method of manufacturing a compound semiconductor single crystal such as a GaAs single crystal by the lateral boat method, in this embodiment, the volume of the seed crystal 1 used at the time of manufacturing was made equal to or more than the volume of the shoulder 2 of the single crystal to be manufactured. By doing so, the amount of heat radiated to the inside of the single crystal in the single crystal growth start region is increased, and a method for producing a compound semiconductor single crystal capable of stably maintaining a good solid-liquid interface shape is provided. Obtainable.

That is, the volume of the single crystal shoulder portion 2 is about 14 cm.
³ become wide 1.5 × the production of GaAs single crystal height 1.5
× Seed crystal 1 having a length of 11 cm ³ was used.

Seed crystal 1 and Ga of 2900 g as a raw material, and n
800m as an additive for obtaining conductive crystals of the shape
A quartz boat containing g is placed on one end of a quartz glass reaction tube, and As3200 g is placed on the other end, and then the quartz glass reaction tube is vacuum-sealed.

This reaction tube was installed in a dual electric furnace, and the boat side (high temperature furnace) was heated to 1200 ° C. or higher and the As side (low temperature furnace).
To about 600 ° C. And after the GaAs synthesis reaction,
While keeping the temperature of the low temperature furnace constant, the temperature of the high temperature furnace is further raised, and the seeded portion has a melting point of GaAs of 1238 ° C.
In addition, the electric furnace is adjusted so as to have a temperature gradient (about 1 deg / cm) so that the boat body side has a higher temperature.

After melting a part of the seed crystal 1 in this way and then cooling the temperature at 1 deg / h while keeping the above temperature gradient to solidify the whole, the temperature gradient of the boat installation part in the electric furnace is changed. After adjusting the setting of the electric furnace again to zero, it is cooled to room temperature at 100 deg / h and the single crystal is taken out. With this method, the weight of GaAs is about 6000 g.
A single crystal was obtained.

As a result of observing the distortion of the obtained single crystal, it was confirmed that the solid-liquid interface shape was convex toward the melt side from the start to the end of single crystal growth, which was good. Thus, according to this example, it is possible to stably maintain a good solid-liquid interface shape in the production of a large single crystal, and it is possible to significantly improve the quality and yield of the produced single crystal. It was

[0016]

As described above, according to the present invention, the volume of the seed crystal used at the time of production is made equal to or more than the volume of the shoulder portion of the single crystal to be produced. It is possible to obtain a method for producing a compound semiconductor single crystal in which the amount of heat radiated to the inside is increased and a stable solid-liquid interface shape can be stably maintained.

[Brief description of drawings]

FIG. 1 is a perspective view of a seed crystal and a shoulder portion of a single crystal according to an embodiment of a method for producing a compound semiconductor single crystal of the present invention.

[Explanation of symbols]

 1 seed crystal 2 single crystal shoulder

Claims (1)

[Claims] 1. A method for producing a compound semiconductor single crystal by a horizontal boat method, wherein the volume of the seed crystal used in the production is equal to or more than the volume of the shoulder portion of the single crystal to be produced. And a method for producing a compound semiconductor single crystal.