JP2000143387A - Production of compound semiconductor single crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for stably producing a continuous compound semiconductor single crystal in high reproducibility with low power consumption. SOLUTION: This method for producing a compound semiconductor single crystal has such advantages that, since the crystal pull-up space A disposed with a PBN crucible 31 inside a high-pressure vessel 16 as an oven and the heating space B disposed with a heater 7 are partitioned from each other with space-partitioning jigs 8, 9, 17 as walls, the amount of a feedstock to be charged can be increased without increasing the amount of the gas to be encapsulated inside the vessel; furthermore, heat can be moderately allowed to escape from crystal surface, therefore increasing no electric power to be charged into the heater 7 during crystal growth; as a result, the aimed continuous compound semiconductor single crystal can be produced stably and in high reproducibility; besides, when a crystal growth is to be conducted by encapsulating the crystal pull-up space A with a gas higher in thermal conductivity than the heating space B, heat is released from crystal surface more efficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a compound semiconductor single crystal.

[0002]

2. Description of the Related Art A GaAs single crystal as a compound single crystal includes a magnetoelectric conversion element, a field effect transistor (FET),
It is used in a very wide range of applications as a substrate for high-speed high-frequency devices such as ICs and LSIs. One of the methods for producing a single crystal of a substrate material used in these devices is a liquid sealing pulling method (hereinafter referred to as “LEC”).

[0003] In the LEC method, a single crystal is produced as follows. A raw material and a liquid sealant having low reactivity with the raw material elements are accommodated in a PBN crucible installed in a pressure vessel, and a predetermined amount of an inert gas (Ar gas or the like) is pressure-sealed inside the vessel.
After that, it is heated by a heater located on the outer periphery of the crucible,
Make a GaAs melt. Thereafter, the seed crystal is brought into contact with the GaAs melt, the seed crystal is gradually pulled up, and the seed crystal is pulled up while controlling to a predetermined diameter, whereby a GaAs single crystal is obtained.

In the production of a single crystal by the LEC method, it is required to charge a larger amount of raw material in a single crystal growth and grow a single crystal as long as possible in order to reduce production cost and improve productivity. I have. There is also a need for a method for growing such single crystals with good reproducibility.

[0005]

However, if the crystal is to be pulled up and grown for a longer time and the charge amount of the raw material is to be increased, a furnace having a larger internal capacity is required. In a furnace with a large internal volume, the amount of gas enclosed therein increases as the volume increases, and the amount of heat escaping through this gas also increases, so the amount of power supplied to the heater during growth must be increased. .

On the other hand, when the amount of electric power increases, the crystal surface is easily heated by radiation from the heater.

When growing a single crystal, it is necessary to release heat from the crystal surface appropriately. If the crystal surface is excessively heated, As dissociates from the crystal surface, leaving only Ga,
This Ga may travel down the surface and drop down, drop to the interface between the crystal and the melt, and become polycrystalline. Also, such A
Even if dissociation of s does not occur, the solid-liquid interface shape cannot be maintained at an appropriate shape for growing a single crystal, and there is a problem that polycrystallization is easily caused.

Accordingly, an object of the present invention is to solve the above-mentioned problems and to provide a method for producing a compound semiconductor single crystal which can stably produce a long compound semiconductor single crystal with good reproducibility and consumes low power. To provide.

[0009]

In order to achieve the above object, a method of manufacturing a compound semiconductor single crystal according to the present invention is directed to a method of manufacturing a compound single crystal by a liquid sealing pulling method. A compound single crystal is manufactured using a manufacturing apparatus having a furnace in which a space and a heating space in which a heater is arranged are partitioned by walls.

In addition to the above structure, in the method of manufacturing a compound semiconductor single crystal of the present invention, it is preferable that a crystal having a higher thermal conductivity than the heating space is sealed in the crystal pulling space and grown.

According to the present invention, since the crystal pulling space and the heating space in which the heater is arranged are partitioned by the wall,
It is possible to increase the amount of charge of the raw material without increasing the amount of gas to be filled therein, and to release heat from the crystal surface appropriately, and to increase the amount of power supplied to the heater during growth. There is no. As a result, a long compound semiconductor single crystal can be stably manufactured with good reproducibility.

When a gas having a higher thermal conductivity than that of the heating space is sealed in the crystal pulling space for growth, the heat of the crystal surface is more efficiently exhausted.

[0013]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a configuration diagram showing an embodiment of an apparatus to which the method of manufacturing a compound semiconductor single crystal according to the present invention is applied.

A high-pressure vessel 16 as a furnace of the present manufacturing apparatus is partitioned by space partitioning jigs 8, 9 and 17 as walls. The space partitioning jigs 8, 9, 17 are formed so as to partition the high-pressure container 16 into an upper part and a central part, and a central peripheral part and a lower part. The upper and central spaces are a crystal pulling space A in which a PBN crucible 31 for pulling a compound single crystal is disposed, and the central outer peripheral portion and a lower space are a heating space B in which a heater 7 is disposed.

In the crystal pulling space A, the PBN crucible 31 is provided on the lower side of the high-pressure vessel 16 and is supported by a crucible support shaft 6 which can move up and down. GaAs is housed in the PBN crucible 31 and is sealed with the liquid sealing tool 4 having a hole formed in the center. A vertically movable and rotatable pulling shaft 1 is provided above the high pressure vessel 16, and a seed crystal 2 is attached to a lower end of the pulling shaft 1. An N ₂ gas cylinder 13 is connected to the crystal pulling space A via a gas pipe 12.

In the heating space B, a heater 7 is arranged on the outer periphery of the center of the high-pressure vessel 16 so as to surround the PBN crucible 31.
0 and 11 are arranged. Gas piping 1 in heating space B
The Ar gas cylinder 15 is connected through the connection 4.

A compound single crystal is produced by the LEC method using such an apparatus.

A predetermined amount of Ar gas and N ₂ gas are pressure-filled in the high-pressure vessel 16. Thereafter, the PBN crucible 31 is heated by the heater 7 to form the GaAs melt 5 in the PBN crucible 31. The GaAs single crystal 3 is obtained by bringing the seed crystal 2 attached to the lower end of the pulling shaft 1 into contact with the GaAs melt 5 and gradually pulling the seed crystal 2.

[0020]

(Embodiment 1) GaAs using the apparatus shown in FIG.
Five s single crystals were grown.

Here, it is known that the thermal conductivity of N ₂ gas is higher than that of Ar gas. After forming 25 kg of a GaAs melt 5 having an excess composition of As in the PBN crucible 31 under a pressure of 20 kg / cm ² , two spaces are formed.
0 kg / cm ² to adjust the seed crystal 2 to Ga
As dipped in As melt 5, diameter about 110 mm, length about 4
Five 30 mm GaAs single crystals 3 were pulled up.

Here, the space partitioning jigs 8 and 9 were formed by coating PBN with low gas permeability on graphite.

Comparative Example 1 FIG. 2 is a conceptual view of an apparatus to which a conventional method for manufacturing a compound semiconductor single crystal is applied.

The difference from the apparatus shown in FIG. 1 is that the crystal pulling space A and the heating space B of the high-pressure vessel 16 are not partitioned, and the gas sealed in the high-pressure vessel 16 is one type. That is the point. The same members as those shown in FIG. 1 have the same reference numerals.

Crystals were grown using the apparatus shown in FIG. In the apparatus shown in FIG. 1, a space partition jig 8 and a space partition jig 9 are arranged, but there is no space partition jig between the space partition jig 8 and the space partition jig 9. The crystal pulling space A and the heating space B are in communication. The high-pressure vessel 16 is connected to a gas cylinder 18 via a pipe 19. The gas cylinder 18 is filled with N ₂ gas. Under pressure of 20 kg / cm ² , PBN crucible 31
After forming 25 kg of a GaAs melt in which s has an excess composition, five crystals having the same shape as in Example 1 were pulled up.

Comparative Example 2 A crystal was grown using the apparatus shown in FIG. The gas cylinder 18 is filled with Ar gas. PBN crucible 31 under a pressure of 20 kg / cm ²
The GaAs melt 21 having an excess composition of As
After the formation of kg, five crystals having the same shape as in Example 1 were pulled up.

(Basis for Optimum Conditions) Table 1 shows the results obtained by examining the generation positions of a total of 15 crystals pulled up by the method shown in Example 1 and Comparative Examples 1 and 2.

[0028]

[Table 1]

From Table 1, it can be seen that the crystals grown by the method of Example 1 are all single crystals and can be grown more stably than the methods of the two comparative examples.

FIG. 3 shows an example and a comparative example of the power consumption of the heater during the crystal growth. That is, for one crystal in total grown by the method shown in Example 1 and Comparative Examples 1 and 2, the heater power (power consumption) is plotted against the pull length. , The horizontal axis is the pull-up length, and the vertical axis is the heater power consumption.

In FIG. 3, white circles indicate Example 1, triangles indicate Comparative Example 1, and black circles indicate Comparative Example 2.

FIG. 3 shows that the method of Example 1 consumes less power than the methods of Comparative Examples 1 and 2.

[0033] In this embodiment, crystal pulling but space A described when grown encapsulating a N ₂ gas, N ₂ gas high He gas and H ₂ gas from a N ₂ gas thermal conductivity in place of May be used. Further, although the case where Ar gas is sealed in the heating space has been described, an inert gas such as Xe having a lower thermal conductivity than Ar gas may be used instead of Ar gas.

In the above description, Ga by the conventional pulling method is used.
Long single crystals can be stably grown with good reproducibility with less heater power consumption than the method of growing As single crystals. For this reason, GaAs substrates can be produced at a lower cost than conventional methods, and the manufacturing cost of elements using these as substrates can be reduced, and their industrial and economic contributions are large.

[0035]

In summary, according to the present invention, the following excellent effects are exhibited.

A long compound semiconductor single crystal can be formed with good reproducibility.
A method for manufacturing a compound semiconductor single crystal that can be manufactured stably and consumes low power can be provided.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of an apparatus to which a method for manufacturing a compound semiconductor single crystal of the present invention is applied.

FIG. 2 is a conceptual diagram of an apparatus to which a conventional method of manufacturing a compound semiconductor single crystal is applied.

FIG. 3 is a diagram showing an example and a comparative example of power consumption of a heater during crystal growth.

[Explanation of symbols]

 7 Heater 8, 9, 17 Space partition jig 16 High pressure vessel 31 PBN crucible

Claims (2)

[Claims] 1. A method for producing a compound single crystal by a liquid sealing and pulling method, comprising a furnace in which a crystal pulling space in which a crucible is disposed and a heating space in which a heater is disposed are partitioned by a wall. A method for producing a compound semiconductor single crystal, comprising producing a compound single crystal using the method. 2. The method for producing a compound semiconductor single crystal according to claim 1, wherein said crystal pulling space is grown by enclosing a gas having a higher thermal conductivity than said heating space.