JPS5973497A - Growth of compound semiconductor crystal - Google Patents

Abstract

PURPOSE:To eliminate the bubbles generated at the interface between the molten liquid of a synthetic compound and a sealing liquid, in a short time, by synthesizing the raw material, reducing the applied pressure of the high-pressure growth furnace instantaneously to the equilibrium dissociation pressure of the synthesized compound or thereabout, and then pressurizing the furnace to the pressure of the pulling of the crystal. CONSTITUTION:For example, in the synthesis and pulling growth of GaAs, the crucible 3 is heated with the heater 2, the furnace 1 is pressurized above the vapor pressure of As at the melting point of GaAs, and the content is heated to the melting point of GaAs to effect the synthesis of GaAs from Ga and As used as the raw materials. Thereafter, the pressure in the high-pressure growth furnace 1 is reduced to about 5atm to generate a number of bubbles at the interface between the molten liquid and the molten B2O3 6 used as a sealing layer. Thereafter, the pressure is further decreased instantaneously to about 0.9atm corresponding to the equilibrium dissociation pressure of GaAs. The decomposition of the molten GaAs takes place, and the generated As vapor pushes up the bubbles over the sealing liquid. When the bubbles are eliminated, the furnace 1 is again pressurized to about 5atm, the seed crystal 7 is brought into contact with the molten GaAs, and the GaAs single crystal is pulled up and grown.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for growing a compound semiconductor crystal, and more particularly to a method for synthetically pulling and growing a compound semiconductor crystal by direct synthesis using a liquid arrest pulling method.

Conventional methods for growing compound semiconductor crystals include the horizontal Bridgeman method, or a method in which polycrystals synthesized using the horizontal Bridgeman method are turned into single crystals by a liquid-sealed pulling method.

However, when the entire crystal is grown by the horizontal Bridgeman method, contamination with St is unavoidable in the grown crystal from the quartz sealed tube 9 quartz boat used, and there is a problem in achieving high purity crystal growth. Furthermore, the growth of long, large-diameter crystals is also limited by the use of sealed tubes.

For this reason, recently, a method has been adopted in which raw materials are completely synthesized directly by a liquid-stopping pulling method and single crystallization is performed after the synthesis. As shown in the figure, direct synthesis and single crystallization by the liquid arrest pulling method include a granoid crucible 3 heated by a cylindrical frequency heating coil or resistance heating heater 2 in a high-pressure growth furnace body 1; Quartz or P B N (Pyrolytio Bor
There is a crucible 4 made by N1tride on N1tride. 5 is a raw material for synthetic pulling growth, 6 is boron oxide (B203)% for sealing solidified into a circular shape, and 7 is a seed for single crystal pulling.

To explain the synthesis and pull growth of GaA3 as an example, we use galineem (Ga) and arsenic (AS) as synthesis raw materials. Pressurize to about 2 to 3 atmospheres with inert gas. Afterwards, the graphide melt is gradually heated by the heating heater 2, and when the temperature of the PBN crucible 4 is raised to 450°C or higher, which is the softening point of boron oxide, the boron oxide placed in the synthetic raw material - 6 softens and melts to cover the synthetic raw material.

After the boron oxide 6 is completely melted, the pressure in the high-pressure growth furnace 1 is increased to about 70 atmospheres, which is higher than the vapor pressure of arsenic at the melting point of QaAs, which has a melting point of 1238°C.

By raising the temperature f after pressurization to the melting point of QaAs, the raw material in the pPBN crucible 4 is synthesized as a GaA3 melt. After synthesis, the pressure in the high-pressure growth reactor 1 is reduced to about 5 atm, which is several atm higher than the equilibrium dissociation pressure of GaAs, which is 0.9 atm, and the temperature of the GILAll melt is reduced. Adjust, bring the seed crystal into contact with the liquid surface, pull up speed, rotation speed of the seed crystal, etc.? Perform crystal pulling growth 2 while controlling.

During the process of raw material synthesis and crystal pulling growth, when the pressure inside the high-pressure growth reactor 1, which had been pressurized to about 70 atm, is reduced to about t-5 atm after the completion of the raw material synthesis, the GILA8 melt and the boron oxide seal are separated. Many bubbles are generated at the liquid stop interface. This bubble is G
ILA! Not only does it make it difficult for the seed crystal to come into contact with the melt surface, but it also adheres to the growing crystal during pulling growth and causes the generation of crystals. Therefore, it is necessary to completely remove these bubbles from the surface of the GaAl melt, but the conventional method was to simply leave them for a while to make them disappear. However, the disadvantage was that it took a long time for the bubbles to disappear.

Is the present invention a drawback of the above-mentioned conventional technology? Is it possible to remove the bubbles generated at the interface between the GaAs melt and the sealing liquid after synthesis in an extremely short time? This made it possible.

According to the present invention, the liquid-sealed pulling method? In a method for growing compound semiconductor crystals in which compound semiconductor crystals are synthesized by direct synthesis and grown by pulling, the pressure in the high-pressure growth furnace is instantly reduced to about the equilibrium dissociation pressure of the synthesized compound after synthesis of the raw materials. The purpose of this method is to remove bubbles generated and retained at the interface between the melt and the sealing liquid out of the sealing liquid in a short period of time.

Is this invention the following? This will be explained using an example.

Using a high-pressure growth furnace 1 configured as shown in the figure, the QaAs raw material is grown using a liquid-sealed pulling method. When performing direct synthesis and pulling growth 2, if the pressure inside the high-pressure growth furnace 1 is reduced from 70 atm to about 5 atm during crystal pulling growth after raw material synthesis, G
A large number of bubbles are generated at the interface between the aA3 melt and the sealing liquid. A seed crystal in this bubble tiGaAs melt? When making contact, it is not only difficult to visually check the contact state (1) to detect MA, but also to cause the generation of Snu crystals that adhere to the growing crystals.
It takes about 1 hour for the bubbles to completely disappear from the surface of the caAs melt. After the bubbles completely disappeared, the seed crystal 7 was brought into contact with the crystal to perform pulling growth 2 of the crystal.

On the other hand, in the method of the present invention, after the synthesis of QaAg, the pressure in the high-pressure growth reactor 1 is reduced from 70 atm to about 5 atm, and then the pressure in the high-pressure growth reactor 1 is reduced to about 0.9 atm, which is the equilibrium dissociation pressure of GaA3. Arsenic from GaA8 melt by instantaneous decompression of gold? The decomposed arsenic vapor causes bubbles generated and retained at the interface between the 5 GtLAB melt and the sealing liquid to be pushed up onto the sealing liquid and removed. After that, when the inside of the high-pressure growth furnace is raised to 5 atmospheres again, the remaining air bubbles have already been removed, so the seed crystal vil'' can be easily formed.
It could be brought into contact with the GaA3 melt, and the entire pulling growth could be carried out without any troubles such as generation of twins.

Compound semiconductor crystal using the liquid-sealed pulling method as described above?
Is the method of the present invention used for direct synthesis and pull growth? By using this method, it is possible to remove all the bubbles generated at the interface between the GaAs melt and the sealing liquid after synthesis in a very short time, and the time required for crystal pulling growth is greatly shortened. A single crystal that does not contain any twinned gold? It has the effect of being lifted up.

[Brief explanation of drawings]

The figure is a diagram for explaining the entire principle of direct synthesis and pulling growth using the liquid-sealed pulling method. In the figure, 1...
High-pressure growth furnace body, 2...Resistance heating heater, 3.
...Grahide crucible, 4 ... Quartz or PBN crucible, 5 ... Raw material for synthesis, 6 ...
...Boron oxide for sealing, 7...Crystal pulling growth tank.

Claims (1)

[Claims] Liquid sealed pulling method? In the total synthesis of compound semiconductor crystals by direct synthesis and the growth method of compound semiconductor crystals by pulling growth, after synthesis of the raw materials, the pressure is instantly reduced to about the equilibrium dissociation pressure of the pressurized gold synthesis compound in the cylinder pressure growth furnace, and then Is it possible to apply pressure to the pressure that should be maintained during pulling growth, and then perform the entire pulling growth? Characteristic method for growing compound semiconductor crystals.