JPS6163591A - Installation for production of single crystal of compound semiconductor - Google Patents

Abstract

PURPOSE:To attaim improved quality of single crystals and increased yield of the product by forming crucible support or insulation part made of a carbon product coated with AIN whereby the temperature distribution is appropriately maintained in the crucible without contamination of the melt for single crystal. CONSTITUTION:The single crystal production unit is composed of a high-pressure vessel 1, a crucible 2, the crucible supports 3, 4, 5, a heater 6 coaxially surrounding the crucible 2 and insulation parts of a cylinder and two plates 12, 13 outside, above and beneath the heater 6. The crucible supports 3, 4, 5 and/or insulation parts of a cylinder and plates 12, 13 are made of carbon coated with aluminum nitride on their surfaces. The objective crucible supports and insulation parts are produced by forming them from graphite, placing them a tightly sealed vessel replaced with a carrier gas such as nitrogen, then introducing aluminum chloride and ammonia gases and heating them at about 1000 deg.C for 5 hours to form aluminum nitride coating films.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an apparatus used for manufacturing compound semiconductor single crystals by the LEC method.

[Technical Background of the Invention and Problems Therewith] The LEC method has been known as a method for producing compound semiconductor single crystals that have a high decomposition pressure at their melting points, such as QaAs, GaP, and InP.

To explain this method using drawings, first, a crucible 2 containing a crystal raw material and a sealant such as 8203 is placed in a high-pressure container 1.
The crucible holder 3.4.5 is placed inside the crucible holder 3.4.5.

Next, the crystal raw material and sealant in the crucible 2 are heated and melted by a heating element 6 coaxially surrounding the crucible 2.

At this time, the crystal raw material melt 7 and the sealant melt 8 are in a two-layer state due to the density difference, and the crystal raw material melt 7 has a large density (the density of the melt is about 5.7Q/, 11 for GaAs, for example).
', InP about 5. O(] /aj, Ga P about 4.
4g/cj), the decomposition and evaporation of the crystal raw material melt 7 is suppressed by being coated with the sealant melt 8 having a small density (melt density is approximately 1.59/cj for B203), and the high-pressure container By pressurizing the inside of crystal material 1 with an inert gas, vaporization of crystal raw material melt 7 can be suppressed.

In this state, the seed crystal 1 attached to the tip of the crystal pulling shaft 9
0 is passed through the sealant melt 8 to avoid contact with the crystal raw material melt 7, and then pulled up while rotating the pulling shaft 9 to obtain the single crystal 11.

In this way, the L E'C method has the advantage of being able to produce single crystals using relatively simple equipment, but the crystal growth is performed under high temperature and pressure, which causes problems such as heat dissipation due to heat convection and uneven temperature distribution. However, it had the disadvantage of having large crystal defects.

For this reason, in order to maintain appropriate altitude distribution within the crucible and ensure heating efficiency of the heating element, heat shielding members 12 and 13 are placed outside and above and below the heating element. . This heat insulating member 12.13 and the crucible holder 3.
4.5, carbon products are usually used because they are easy to shape and lightweight.

However, carbon products are easily oxidized and deteriorated by atmospheric gas, trace amounts of V elements in B203, water vapor, or oxygen and water vapor contained in the carbon product itself due to adsorption, so the durability of carbon products decreases. Needless to say, there was a problem in that the oxidation reactants flew into the crucible being stirred by the high-pressure gas convection, contaminating the crystal raw material.

[Objective of the Invention 1] The present invention has been made to solve such problems, and it is possible to maintain an appropriate temperature distribution in the crucible without contaminating the crystal raw material melt, thereby improving the quality and yield of single crystals. An object of the present invention is to provide a compound semiconductor single crystal manufacturing apparatus that can improve the performance.

[Summary of the Invention] That is, the compound semiconductor single crystal manufacturing apparatus of the present invention includes a high-pressure container, a crucible and a crucible holder arranged in the high-pressure container, a heating element surrounding the crucible and the crucible holder, In a compound semiconductor single crystal manufacturing apparatus mainly comprising a heat insulating member disposed outside and above and below the heating element, and a crystal pulling device disposed on the crucible so as to be able to rise and fall, the crucible holder and It is characterized in that the heat insulating member is made of a carbon product whose surface is coated with aluminum nitride.

In the present invention, a chemical vapor deposition method is preferred as a method for coating the surface of aluminum nitride. Coating a carbon member with aluminum nitride by chemical vapor deposition is carried out by a conventional method, for example, the following method.

That is, by purchasing a carbon product that has been formed into a predetermined shape in an atmosphere of aluminum halide and ammonia gas carrier gas and heating it at a high temperature of 900 to 1200°C, a carbon product whose surface is coated with aluminum nitride can be obtained. . Note that the thickness of aluminum nitride is desirably in the range of 1 to 50 μm, since it will not be effective unless it is too thick, and on the other hand, if it is too thick, there is a risk of cracking on the surface.

Note that plasma spraying and physical vapor deposition can also be applied as a method for coating the surface of aluminum nitride.

[Embodiments of the invention] Next, examples of the present invention will be described.

Embodiment As shown in the drawings, the apparatus of the present invention includes a high-pressure vessel 1, a crucible 2 and a crucible holder 3, 4, 3, 4, 4, 4, and 4 disposed within the vessel.
5, a heating element 6 coaxially surrounding the crucible 2, and cylindrical and plate-shaped heat insulating members 12 and 13 disposed on the outer periphery of and above and below the heating element 6. Here, the crucible holder and the heat retaining member were manufactured by the following method.

After manufacturing a crucible holder and a heat insulating member of a predetermined shape from graphite, place them in a sealed container, replace the inside of the container with a carrier gas such as nitrogen gas, and then introduce aluminum chloride and ammonia gas, Next, heating was performed at approximately 000° C. for 5 hours to form an aluminum nitride film with a thickness of 10 μm.

When a GaAS single crystal was pulled by the conventional method using the crucible holder and heat insulating member obtained in this way, contamination of the crystal raw material melt was reduced, and carbon impurities in the obtained single crystal were reduced. It was about 1/3 or less.

Furthermore, the heating efficiency of the heating element has been improved, and the temperature distribution within the crucible can be made more uniform, making it possible to produce stable single crystals with few crystal defects.

In the above embodiments, both the crucible holder and the heat insulating member are made of carbon products whose surfaces are coated with aluminum nitride, but it is also effective to make a carbon product whose surface of only either one is coated with aluminum nitride.

[Effects of the Invention] As explained above, according to the apparatus of the present invention, the deterioration of the crucible holder and the heat insulating member is reduced, and the heating efficiency of the heating element is improved and the temperature inside the crucible is improved without contaminating the crystal raw material melt. Since the temperature distribution can be made uniform, a high quality compound semiconductor single crystal can be manufactured.

[Brief explanation of the drawing]

The drawing is a sectional view schematically showing an embodiment of the device of the present invention. 1・・・・・・・・・・・・・・・High pressure container 2・・・・
・・・・・・・・・・・・ Crucible 3.4.5... Crucible holder

Claims (2)

[Claims] (1) A high-pressure container, a crucible and a crucible holder arranged in the high-pressure container, a heating element surrounding the crucible and the crucible holder, and a heat-retaining member arranged outside and above and below the heating element. , in a compound semiconductor single crystal manufacturing apparatus mainly comprising a crystal pulling device disposed on the crucible so as to be freely raised and lowered, the crucible holder and/or the heat insulating member are made of a carbon product whose surface is coated with aluminum nitride. 1. A compound semiconductor single crystal manufacturing device characterized by comprising: (2) The compound semiconductor single crystal manufacturing apparatus according to claim 1, wherein the surface coating with aluminum nitride is performed by a chemical vapor deposition method.