JPS62270486A - Production apparatus for gaas single crystal - Google Patents

Abstract

PURPOSE:To sustain constant growth condition of a crystal in the longitudinal direction and obtain a long and high-quality GaAs single crystal, by moving a heat radiation means together with a solid-liquid interface. CONSTITUTION:A quartz ampul 4 having a partition wall permitting the flow of vapor in the center thereof is placed in a twin electric furnace 1 consisting of a high- temperature furnace 2 equipped with a heating element 10 in the longitudinal direction and a low-temperature furnace 3 an a quartz boat 7 containing Ga or GaAs 5 and a seed crystal 6 is placed on the high-temperature side of the ampul 4 and As 8 in excess is placed on the low-temperature side thereof. An opening part 12 of a heat radiation member 13 is then closed to heat the furnace 2 to 1,300 deg.C and the furnace 3 to about 610 deg.C. Thereby eutectic reaction of the GaAs is carried out in the boat 7 and the temperature distribution of the boat 7 is formed so that the side of the seed crystal 6 may be the low-temperature side and the opposite side may be the high-temperature side. A quartz plate 14 on the opening part 12 of the heat radiation member 13 is then opened and the heat radiation member 13 is simultaneously moved to place the opening part 12 just above the seed crystal 6 and carry out seeding. The temperature is then lowered to start growth of a single crystal 5, which is grown while always positioning the opening part 12 above the solid-liquid interface 16.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to equipment for producing single crystals of Ga 8, and particularly relates to equipment for producing long single crystals by a temperature gradient method. It is something.

[Prior Art] One of the methods for manufacturing GaAs single crystals is a horizontal boat method using a quartz boat. This horizontal boat method can be roughly divided into the temperature gradient method and the furnace moving method, but compared to the latter method, the former method produces fewer vibrations and higher quality crystals because it does not have a mechanical drive. , ■ The length of the device is approximately 172 to 273 mm, so it is small; ■ Since the furnace body does not move, the ampoule does not need to be floated independently from the furnace body; ■ The device can be put to practical use at low cost. It has advantages and is widely used.

[Problems to be Solved by the Invention] However, in the temperature gradient method, it is necessary to keep the crystal growth conditions constant, and therefore a furnace that can form a stable temperature gradient over the entire length of the boat is required.

Such a furnace generally requires a heat dissipation means such as a heat dissipation hole to dissipate heat from the furnace body, and in order to form a stable temperature gradient as described above, the length of this heat dissipation means is longer than the length of the crystal. It has to be long. Therefore, when producing long crystals, the furnace structure becomes complicated and it becomes difficult to make the amount of heat radiated from the heat radiating means uniform in the length direction of the crystal.

For example, if a long heat dissipation hole is provided in the upper part of the furnace body, the amount of heat dissipated from a unit surface area of the crystal increases because the opening angle becomes large. Therefore, if it is attempted to change the shape of the heat radiation hole for the purpose of making the amount of heat radiation constant, the three-dimensional temperature distribution within the furnace will change, which is not preferable.

That is, it is difficult to produce a long GaAs single crystal with good quality using the temperature gradient method.

SUMMARY OF THE INVENTION Thus, an object of the present invention is to solve the problems of the prior art described above and to provide a GaAs single crystal production apparatus capable of producing long and high quality GaAs single crystals by the temperature gradient method.

[Means for overcoming the problem] In order to achieve the above-mentioned goal 1, the GaAs single crystal manufacturing apparatus of the present invention is equipped with a seed crystal placed at one end and a GaAs single crystal manufacturing apparatus according to the present invention.
A growth boat containing the molten liquid is placed in the furnace body, and the temperature distribution formed in the length direction of the boat is changed to move the solid-liquid interface from the seed crystal in the opposite direction,
In the apparatus for growing a single crystal by crystallizing the GaAs melt, a heat dissipation means that moves in the opposite direction from the seed crystal together with the solid-liquid interface and is always located above the solid-liquid interface is attached to the furnace body. It is installed at the top.

[Function] By installing the heat dissipation means as described above in the upper part of the furnace body and moving it in accordance with the crystal growth, the amount of heat dissipation from the vicinity of the solid-liquid interface is always constant. In other words, even when producing long crystals, the growth conditions in the bow length direction can be kept constant.

Since the heat dissipation means moves together with the solid-liquid interface, the length of the heat dissipation means can be made shorter than the boat length.

Embodiment] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. l FIG. 1(a) is a diagram showing the failure of a GaAs single crystal manufacturing apparatus according to an embodiment of the present invention.

In the figure, reference numeral 1 denotes a double-barrel electric furnace consisting of a high-temperature furnace 2 and a low-temperature furnace 3, and a sealed quartz ampoule 4 is disposed within the double-barrel electric furnace 1. A partition wall is provided in the center of the quartz ampule 4 to allow the flow of steam, thereby dividing the quartz ampule 4 into sections. On the high temperature side of the quartz ampoule 4, a seed crystal 6 of Ga or GaAs 5, which is a raw material for growth, is placed.
A quartz boat 7 accommodating 1 and 2 is loaded with excess As8 on the low temperature side.

A thermocouple 9 for temperature monitoring is connected to the end of the low temperature side quartz ampoule 4 on which the excess As8 is placed.

= 5- By the way, the high temperature furnace 2 has a heating element 10 arranged in the length direction thereof and a heat insulating material 11 provided on the outer periphery of the heating element 10.
and has a slightly longer shape than the quartz boat 7. Further, the heat insulating material 11 located above the quartz boat 7 has a width of approximately 50 m, and a portion approximately the length of the quartz boat 7 has been cut out, and the upper part of this heat insulating material 1'l has a length of 300 mm.

A heat radiating member 13 having an opening 2 with a width of 30 mm is provided so as to be movable in the longitudinal direction of the furnace. In addition, the heat dissipation member 1
Two transparent quartz plates 14 are attached to the opening 12 of No. 3 in a stacked manner so as to be openable and closable.

Next, the operation of this embodiment will be described with reference to the temperature distribution diagram of FIG. 1(b).

First, in the quartz boat 7 there is 3500g of Ga, ^5380g.
After evacuating the inside of the quartz ampule 4 to 5× 10 Torr or less for 1 hour, the quartz ampule 4 was sealed and placed in a furnace as shown in FIG. 1(a).

Then, with the opening 12 of the heat dissipation member 13 closed, the high temperature furnace 2 is heated to 1200°C or more, the low temperature furnace 3 is cooled to about 610°C, and a GaAs eutectic reaction is performed in the quartz boat 7. , a temperature gradient of 1°C/cm is applied over the entire length of the quartz boat 7 so that the seed crystal 6 side is low temperature and the opposite side is high temperature side.
A temperature distribution was formed.

Thereafter, the quartz plate 14 of the opening 12 of the heat radiating member 13 is opened and the heat radiating member 13 is moved so that the opening 12 is positioned directly above the seed crystal 6.

Then, while keeping the temperature gradient constant, the temperature was gradually increased to set the temperature near the -C weighing crystal 6 to the melting point Tm of GaAs, and seeding was performed.

After seeding is completed, the temperature is heated at 1° C./h while maintaining the temperature gradient, and the growth of the single crystal 15 is started.

As the temperature decreases, the solid-liquid interface 16 moves in the opposite direction from the seed crystal 6.
3 in the same direction so that the opening 12 is always located above the solid-liquid interface 16. As a result, if the opening 12 is not located at the top near the solid-liquid interface 16 (distribution 17)
A cooling effect (shaded area) occurs compared to the above, and a temperature distribution 18 is formed.

By continuing to lower the temperature in the same manner and moving the solid-liquid interface 16 to the rear end of the quartz boat 7 through the temperature distribution 19, the entire melt is crystallized and solidified. Thereafter, the inside of the furnace was cooled to room temperature at a rate of 50° C./h.

In this way, a GaAs single crystal with a total length of 800 m could be obtained. (100)-plane wafers are cut out from both ends and the center of this single crystal, and these are melted into KO
As a result of etching with H and measuring the dislocation density, EPD (
It was confirmed that the crystal was a low dislocation crystal with an etch pit density of ≦2000/cm2.

In the above embodiment, a member having an opening is used as a heat dissipation means, but the present invention is not limited to this, and a cooling device such as water cooling may be provided in the furnace.

[Effects of the Invention] As explained above, according to the present invention, the following excellent effects are exhibited.

(1) By moving the heat dissipation means together with the solid-liquid interface, the growth conditions in the length direction of the crystal can be kept constant.

(2) Therefore, it becomes possible to produce long and high quality GaAs\ crystals using the temperature gradient method.

[Brief explanation of the drawing]

FIG. 1(a) is a block diagram of a GaAs single crystal production apparatus according to an embodiment of the present invention, and FIG. 1(b) is a distribution diagram of the embodiment. In the figure, 1 is an electric furnace, 5 is a GaAs melt, 6 is a seed crystal, and 7
is a quartz boat. 12 is an opening, 13 is a heat dissipation member, and 16 is a solid-liquid interface.

Claims (3)

[Claims] (1) A growth boat with a seed crystal placed on one end and containing a GaAs melt is placed inside the furnace, and the temperature distribution formed in the length direction of the boat is changed to create a solid-liquid boundary. In an apparatus for growing a single crystal by crystallizing and solidifying the GaAs melt by moving the plane from the seed crystal in the opposite direction, the solid-liquid interface moves from the seed crystal in the opposite direction together with the solid-liquid interface, and the solid-liquid surface always moves from the seed crystal in the opposite direction. A GaAs single crystal production apparatus characterized in that a heat dissipation means located above the boundary surface is provided in the upper part of the furnace body. (2) The manufacturing apparatus according to claim 1, wherein the heat radiating means is shorter than the length of the growth boat. (3) The manufacturing apparatus according to claim 2, wherein the heat radiation means comprises a heat radiation hole.