JPS606917B2 - Method for producing Group 3-5 compound semiconductor single crystal - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a high quality m-V group compound semiconductor single crystal.

Single crystals of m-V group compounds, such as GaAs, Gap, and lnP, exhibit excellent properties as semiconductors, and are used in elements used in optoelectronics such as light-emitting diodes and semiconductor laser devices, microwave diodes, field-effect transistors, etc. It is widely used in the manufacture of high-frequency devices.

Furthermore, it is attracting attention as a substrate crystal for ultra-high-speed logic integrated circuits and optoelectronic integrated circuits. For the growth of single crystals of these compounds, a high-pressure liquid sealing method (LES method) using a liquid sealant has been commonly used since group V elements such as As and P exhibit high dissociation pressure.

This liquid-sealed pulling method uses a large ayase crystal, and m-V
It has the characteristic that even compounds whose volume changes during crystallization, such as group compounds, can be easily made into single crystals. Under high pressure, the dissociation of Group V elements such as P, which have a high dissociation pressure, is suppressed, and the crystal is grown by bringing the seed crystal into contact with the melt, rotating and pulling it at a predetermined speed. As mentioned above, in the liquid sealing pulling method, single crystals are grown under high pressure in order to prevent crystal dissociation, so the temperature gradient near the interface between the crystal raw material melt and the sealant is as high as 8000/skin or more. This caused distortion in the grown crystal, causing dislocations.

Further, in a wafer obtained by cutting a crystal pulled in the <100> direction, which is commonly used, and cut along the (100) plane, the dislocation density exhibits a W-shaped non-uniform distribution in the straight direction. In order to avoid the above-mentioned drawbacks, during the crystal growth operation, the atmospheric pressure in the high-pressure container may be lowered, or the Rubbo position in the high-pressure container may be lowered to reduce the temperature gradient at the interface between the crystal raw material melt and the sealant. However, it is difficult to set the optimal temperature distribution and atmospheric pressure with good reproducibility for high-quality crystal growth with few crystal defects, and in particular, if the pressure is lowered too much, As , P are scattered, making it impossible to obtain a single crystal with a predetermined composition ratio. The purpose of this invention is to grow a Yamaichi Group V compound single crystal with low defects and excellent uniformity of dislocation density distribution by creating a low temperature gradient at the interface between the crystal raw material melt and the sealing agent. To provide a method for manufacturing with good reproducibility.

For this reason, the present invention provides blood-V
In the method for producing single crystals of group compounds, crystal growth is performed under a low temperature gradient at the interface between the crystal raw material melt and the liquid sealant, while covering the seed crystal and the grown crystal with the liquid sealant flowing down from above. It is characterized by doing the following.

The present invention will be explained based on the accompanying drawings. FIG. 1 is a schematic diagram of a single crystal manufacturing apparatus for liquid-sealed pulling.
In a high-pressure container 1 equipped with an inert gas inlet pipe 9 and an exhaust pipe 10, a rubbo 3 made of quartz, poron nitride, etc. is provided in a support member 4 made of carbon material, and can be rotated and moved up and down by a support shaft 6. A heater 2 is provided around Rubbo 3 to heat and maintain Rubbo at a predetermined temperature, and an insulating wall 7 is further provided around the heater 2 to prevent heat radiation from the heater to the outside. do.

A pulling shaft 5 with a seed crystal 8 attached to the lower end is provided in the upper part of Rubbo, and this pulling shaft is configured to rotate and move up and down in the same way as the support shaft 6. In the single crystal manufacturing apparatus as described above, a container 14 is provided midway in the height direction of the pulling shaft 5 with a seed crystal 8 attached to the lower end, and a portion 15 (see FIG. )
A slight gap is provided in the container 15, and the liquid sealant 16 contained in the container 14 flows down along the pulling axis through the gap 15 during the crystal growth process. The container 14 is fixed to the pulling shaft or the inner wall of the high-pressure container by an appropriate method (not shown). A crystal material raw material and a sealant raw material are put into Rubbo 3, a sealant raw material is put into a container i4, and an inert gas such as nitrogen or argon is then pressurized into the high pressure container 1.
Rubbo is heated above the raw material melting temperature to melt the crystal material and sealant. As a sealing agent, a well-known oxidized oxide (&0
3) is used. The raw material for the crystal material to be put into Rubbo is Ga.
In the case of polycrystalline compounds such as lnP and impurities for making them semi-insulating, the crystal material raw material is melted at a low pressure of about 3 to 1 positive atmosphere. Moreover, instead of the m-V group polycrystal, the constituent elements may be placed in a rubbo and the raw materials may be directly synthesized under high pressure of 30 to 7 pi atmospheres.

In either case, once the raw material in Luppo is completely melted,
The interface between the crystal raw material melt 13 and the liquid sealant 12 is heated to 50°C.
'A low temperature gradient below skin level. Methods to create a low temperature gradient at this interface include lowering the pressure inside the high-pressure container, lowering the Rubbo position to increase the heating temperature of the sealant, and as shown in Figure 2, opening the Rubbo 3. Examples include a method in which a reflective plate 17 is provided above the □ surface to reflect the heat radiated from the open □ surface toward the Lubbo. The above-mentioned methods may be used in combination of two or three. When the interface has a low temperature gradient of a predetermined value, the pulling shaft is lowered, the seed crystal 8 is brought into contact with the crystal raw material melt 13, and the temperature gradient is lowered to a predetermined value. The seed crystal is rotated and pulled up at a speed of 100 to grow the crystal. At this time, since the temperature gradient is low, when the formed crystal protrudes from the upper surface of the sealant 12, the specific component radiates from the crystal surface. However, the sealant 16 is not included in the container 14 provided in the drawer 5.
is melted by the temperature inside the high-pressure container, and the interval 1
5, it flows down along the pulling shaft.

At this time, the temperature inside the high-pressure container is about 600 to 1000°C, the viscosity of the sealant has decreased, and the sealant flowing down the pulling shaft constantly covers the surfaces of the seed crystal 8 and growing crystal 11. Since the seed crystal flows down into the rubbo, the scattering of components from the above-mentioned molded crystal is suppressed, and breakage and falling of the seed crystal during the pulling operation can be prevented. The size of the container containing the sealant is such that it can contain enough sealant to cover the seed crystal and single crystal during the crystal growth process, but the amount of sealant flowing down can be controlled by the gap. and 2 to 1
A flow of 0 tm/hour can coat crystal surfaces of 2 to 3 inches in diameter. In this case, add 500~200cm of water.
When a wet type string 03 containing a cape is used, the viscosity is lowered, so that the flow is effectively performed and good results are obtained. Furthermore, the bottom surface of the liquid sealant storage container can be structured to reflect infrared heat and can be used in place of a reflecting plate.

During the crystal growth process, the seed crystal and the surface of the formed crystal are coated with a liquid sealant to suppress the scattering of crystal components, making it possible to obtain high-quality single crystals with a uniform dislocation distribution with good reproducibility, and with a particularly low Although it is effective in a crystal growth process under a temperature gradient, it is clear that the effect can be seen even when used in a normal crystal growth process under a temperature gradient. Next, examples of the present invention will be described.

Ga500, As550, B031 as a sealant
B20330 was added to the container installed on the pulling shaft, nitrogen gas was injected into the high-pressure container to create a pressure of 2 pressure, and the crucible was heated to 1260°C with a heater to synthesize the raw materials. I did it.

Once the raw materials in Rubbo were completely melted, the pressure was lowered to 6 atmospheres. At this time, the temperature gradient at the interface between the raw material melt and the sealant was about 30 qC/skin. The seed crystal was brought into contact with the raw material melt and pulled up at a rate of 5 crystals/hour to create a Ga pseudo single crystal with a diameter of about 50 ribs and a length of about 10 ribs. During the single crystal pulling operation, the 03 melt flows down along the pulling twill,
The surface of the seed crystal and growing single crystal was continuously coated. After cutting out the central part of the single crystal obtained in this way and measuring the dislocation density of this wafer, the twill part was found to be 3×
1 Bika-2, the central part is 7 x 1 case-2,
It shows a U-shaped distribution. For comparison, we attempted to produce a single crystal using the same method except for coating with B203 melt, but
Many defects are seen on the outer periphery of the obtained crystal, and about half of the diameter is unusable, resulting in a significant decrease in value as a product.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of a single crystal manufacturing apparatus, and FIG. 2 is a cross-sectional view of essential parts of a single crystal manufacturing apparatus according to the present invention. In the figure, 1 is a high pressure vessel, 2 is a heater, 3 is a rubbo, and 5 is a pulling shaft. , 8
11 is a seed crystal, 11 is a growing crystal, 12 is a liquid sealant, 13 is a crystal raw material melt, 14 is a container, and 16 is a liquid sealant. Figure 1 Figure 2

Claims (1)

[Claims] 1. In a method for producing a III-V compound single crystal using a liquid sealing pulling method, a liquid sealant is caused to flow down along a pulling rod during the single crystal pulling operation, and the seed crystal and the surface of the formed crystal are sealed with the liquid. A method for producing a single crystal characterized by growing the crystal while being coated with an agent.