JPH06128096A - Method for producing compound semiconductor polycrystal - Google Patents

Abstract

(57) [Abstract] [Purpose] To prevent carbon from being mixed and to control the carbon concentration to a desired concentration when manufacturing a polycrystal as a raw material for growing a compound semiconductor single crystal such as GaAs or Inp. What I did. [Constitution] A compound semiconductor material is filled in a crucible 5 supported by a susceptor 8 in an airtight container filled with an inert gas, and the material is melted by a heater 3 around the crucible and cooled from the lower end of the crucible to grow crystals. A method for producing a compound semiconductor polycrystal, which comprises performing a lid 10 on the crucible to control the carbon concentration of the polycrystal in the method for producing a compound semiconductor polycrystal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a compound semiconductor polycrystal such as GaAs, Inp or the like, which is a raw material for growing a compound semiconductor single crystal, in which the carbon concentration can be controlled.

[0002]

2. Description of the Related Art A single crystal of a compound semiconductor is grown by a liquid sealing pulling method (LEC method), a vertical temperature gradient method (VGF method), a liquid sealing vertical Bridgman method (LE-VB method) and the like. In either method, a compound semiconductor polycrystal is used as a raw material for growth. The compound semiconductor polycrystal is manufactured by the method shown in FIG. In the figure, 1 is a pressure vessel, 2 is a carbon hot zone, 3 is a carbon heater, 4 is a crucible holder, 5 is a crucible, and the pressure vessel 1 is filled with an inert gas such as Ar or N _2. The crucible 5 is filled with a compound semiconductor material such as Ga and As, the material is melted by the heater 3 on the outer periphery of the container, and the polycrystal is grown by gradually cooling from the lower end of the crucible.

[0003] Ga, surface materials such as As, in the course of crystal growth, the dissociation of the V group elements from the melt, is covered with a liquid sealant 6 ₂ 0 _3, etc. B in order to prevent transpiration There is.
However, in the process of melting the material to growing the crystal, free carbon generated from the hot zone made of carbon or the heater made of carbon is mixed as solid or Co ₂ into the grown crystal 7 through B ₂ O ₃ from above the crucible. To do. The concentration of carbon mixed in the grown crystal varied depending on the crystal growth conditions, and a polycrystal having a constant carbon concentration could not be obtained.

Using the above polycrystal as a raw material, LEC method, V
When a single crystal was grown by the GF method, LE-VB method or the like, it was difficult to control the carbon concentration in the single crystal because it depends on the carbon concentration of the raw material. The carbon in the single crystal affects the characteristics of the substrate such as the specific resistance of the single crystal, the ultra-high speed integrated circuit, the optoelectronic integrated circuit, etc., and eliminates the mixing of carbon in the polycrystal of the raw material and the carbon concentration. It was desired to freely control the.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been made as a result of studying the above-mentioned problems, and it is possible to eliminate the incorporation of carbon into a compound semiconductor polycrystal and to freely control the carbon concentration in the polycrystal. This is the development of a possible manufacturing method.

[0006]

According to the present invention, a compound semiconductor material is filled in a crucible supported by a susceptor in an airtight container filled with an inert gas, and the material is melted by a heater around the crucible. A method for producing a compound semiconductor polycrystal, which comprises cooling and performing crystal growth, wherein the crucible is capped to control the carbon concentration of the polycrystal. A method for producing a compound semiconductor polycrystal according to claim 1, wherein an appropriate amount of carbon is added in advance to the lower part of the crucible to control the carbon concentration of the polycrystal, and an appropriate amount is added to the lid of the crucible. The method for producing a compound semiconductor polycrystal according to claim 1 is characterized in that the hole of 1 is provided to control the carbon concentration of the polycrystal.

[0007]

In other words, according to the present invention, by covering the crucible with a lid made of PBN or the like, it is possible to prevent the mixture of carbon from the outside, such as a heater made of carbon, to obtain a high-purity polycrystal. A predetermined amount of carbon is added and placed, and the carbon is doped so that a polycrystal having a desired carbon concentration can be obtained. The lid may be placed on the upper portion of the crucible, or may be placed on the crucible holder. In addition to the above, as a means for doping carbon, a hole of a predetermined size and number is provided in the upper part of the lid, and external carbon is taken into the crystal through this hole to obtain a polycrystal having a desired carbon concentration. be able to. The present invention can be applied to the production of polycrystals in which carbon is a problem in addition to GaAs and Inp.

[0008]

EXAMPLES An example of the present invention will be described below. Example 1 A GaAs polycrystal was grown using the apparatus shown in FIG. The pressure vessel 1 was filled with Ar, and 1800 g of Ga, 1940 g of As, 1940 g of As, and GaAs with a known carbon concentration, and B ₂ O ₃ were formed on the crucible 5 made of PBN having a diameter of 4 inches.
About 160 g of the liquid sealant 6 was stored. A lid 10 made of PBN is put on the crucible holder 4, and Ga and As are melted by heating the heater 3. The pressure in the pressure vessel at that time was 70 atm. After that, the power of the heater was reduced or the crucible susceptor 8 was moved downward to solidify the crucible from the lower part toward the upper part to perform crystal growth.

As described above, G having various carbon concentrations is used.
An aAs polycrystal was prepared and the relationship between the carbon doping amount and the carbon concentration was investigated. The result is shown in FIG. As is clear from FIG. 2, the carbon doping amount and the carbon concentration in the obtained polycrystal are in proportion to each other. Thereby, the carbon concentration in the polycrystal can be set to a desired concentration. In addition, the carbon concentration was zero in the case where carbon was not doped because there was no mixing of carbon from the outside.
Therefore, it can be seen that the cover can prevent the mixture of carbon from the outside.

Next, instead of adding carbon into the crucible, the lid on the crucible was opened with 1 to 10 holes having a diameter of 5 mm, and the carbon was mixed from the outside to be doped. Was found to be approximately proportional to the number of holes. Therefore, it is possible to control the concentration of carbon in the polycrystal by mixing carbon from the outside by forming an appropriate amount of holes in the lid.

Example 2 Using a polycrystal having a known carbon concentration produced by the method of Example 1, a GaAs single crystal was pulled up and the solidification rate of the single crystal (ratio of crystal solidification to the raw material melt) and the carbon concentration were compared. I investigated the relationship. The result is shown in FIG. As is clear from FIG. 3, the conventional method of doping carbon with Co ₂ is unstable because the carbon concentration increases as the solidification rate increases. On the other hand, when the carbon-containing polycrystal obtained by the method of the present invention is used, the solidification rate is proportional to the carbon concentration, and it is understood that the carbon concentration can be easily controlled.

[0012]

As described above, according to the present invention,
It is possible to prevent the mixture of carbon from the outside of the crucible during the growth of the polycrystal and obtain a polycrystal in which the carbon concentration is controlled to a desired concentration, which is a remarkable industrial effect.

[Brief description of drawings]

FIG. 1 is a schematic diagram illustrating a method for producing a compound semiconductor polycrystal according to an embodiment of the present invention.

FIG. 2 is a diagram showing the relationship between carbon concentration and carbon doping amount according to an embodiment of the present invention.

FIG. 3 is a diagram showing the relationship between carbon concentration and solidification rate according to an example of the present invention.

FIG. 4 is a schematic diagram illustrating a conventional method for producing a compound semiconductor polycrystal.

[Explanation of symbols]

 1 Pressure-resistant container 2 Hot zone 3 Heater 4 Crucible holder 5 Crucible 6 Liquid sealant 7 Growing crystal 8 Crucible susceptor 9 Thermocouple 10 Lid

Claims (3)

[Claims] 1. A crystal growth is carried out by filling a compound semiconductor material in a crucible supported by a susceptor in an airtight container filled with an inert gas, melting the material by a heater in the surrounding, and cooling from the lower end of the crucible. A method for producing a compound semiconductor polycrystal, wherein the crucible is covered to control the carbon concentration of the polycrystal. 2. The method for producing a compound semiconductor polycrystal according to claim 1, wherein an appropriate amount of carbon is added in advance to the lower portion of the crucible to control the carbon concentration of the polycrystal. 3. The method for producing a compound semiconductor polycrystal according to claim 1, wherein the crucible lid is provided with an appropriate amount of holes to control the carbon concentration of the polycrystal.