JPH02283690A - Production of single crystal of compound semiconductor - Google Patents

Abstract

PURPOSE:To prevent bleeding of high dissociation pressure component and texture roughening of the surface of single crystal by sealing gap between inner wall of growing vessel and sealing cap of growing vessel with liquid metal and growing single crystal of compound semiconductor. CONSTITUTION:Polycrystalline raw material 2 and seed crystal 1 are enclosed in a growing vessel A1 and metal having low melting point 8 such as Ga or In is set between tapered part 7 at upper end of the vessel A1 and cap 3. Next, the vessel A1 is set in a furnace, then inside of the furnace and inside of the vessel A1 are evacuated, thus inert gas purged out after once re-pressurized inside of the vessel with the inert gas. Further, temperature of a heater B is raised to melt the low-melting metal 8 and the vessel is sealed by penetration of resultant liquid metal into gap with the cap 3. Next, high dissociation pressure component 4 is heated by a heater C and sublimated, then inside of the vessel A1 is filled with gas of the high dissociation pressure component through a perforated hole 10 having small diameter to grow the aimed single crystal of compound semiconductor.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to VGF (vertical
The present invention relates to a method for manufacturing a compound semiconductor single crystal using the Gradient Freeze method, and more specifically to a method for manufacturing a compound semiconductor single crystal using an improved sealing method for a growth chamber of a manufacturing device.

[Prior Art] Fig. 2 is a schematic diagram showing the equipment configuration of a conventional single crystal growth method using the VGF method, and as shown in the figure, a seed crystal 1 and a raw material polycrystalline body 2 are enclosed. In a state where the growth chamber (growth vessel) A is surrounded by an upper heater B for melting the raw material and a lower heater C provided for sublimating the high dissociation pressure component 4, the polycrystalline raw material 2 is sequentially heated vertically from one end. By heating and melting the seed crystal, a single crystal is grown at one end of the seed crystal [References: W. A. Gold et al., Journal of Crystal Growth, 74 (1986
), pp. 491-506, Amsterdam].

FIG. 3 is a diagram showing in detail the structure of the growth vessel A in FIG. 2, where A3 is the growth vessel, 3 is a cap, 4 is a high dissociation pressure component, 5 is a susceptor, 6 is a crucible made of pBN,
7 is solid In. In the apparatus shown in FIG. 3, immediately before the start of single crystal growth, the raw material polycrystalline body 2 is melted by heating by the upper stage heater B, and exists in a state in which it is in contact with the seed crystal 1. In order to prevent the high dissociation pressure component from volatilizing from the molten raw material, the high dissociation pressure component 4 is heated by the lower stage heater C to generate a high dissociation pressure component gas, which is then transferred to the vessel A through the small through hole IO provided in the susceptor 5. , to be introduced within. Baie Saucel A,
The upper heater B that heats the interior is a two-zone type, with two
A temperature gradient is formed in the longitudinal direction (vertical direction) of the cell A by changing the power ratio of the zones. By adjusting the heater power, the low temperature side of the temperature gradient is maintained below the melting point of the raw material, and the high temperature side is maintained above the melting point of the raw material. When such a temperature gradient is made to advance from the seed crystal side to the melt side by adjusting the /f ratio of the two-zone heater B, the melt solidifies from the seed crystal side and a single crystal is grown.

[Problems to be Solved by the Invention] In the conventional method described above, a minute hole 9 is made in the cap 3 at the opening of the growth vessel A. this is,
Although the growth vessel A3 is provided so that the inside of the growth vessel A3 is evacuated at the same time when the inside of the furnace is evacuated, the high dissociation pressure component gas filled in the growth vessel A3 leaks during crystal growth.

Therefore, it was impossible to fill the inside of the growth vessel A with a high dissociation pressure component gas above a certain pressure. This results in an increase in dislocation density and the generation of lineage due to the leakage of high dissociation pressure components in the grown crystal, and improvements in this point have been sought.

The present invention eliminates the drawbacks of the conventional method as described above, and prevents the high dissociation pressure component from falling out and causing skin roughness (
The aim is to provide a new method that can produce high-quality compound semiconductor crystals with a desired composition.

[Means for Solving the Problems] The present invention provides a method for growing a compound semiconductor single crystal in a growth chamber filled with a gas containing a high dissociation pressure component of the compound semiconductor single crystal by the VGF method. This method of producing a compound semiconductor single crystal is characterized in that liquid metal is allowed to seep into the gap between the growth chamber and the sealing cap, and the inside of the growth chamber is sealed for growth.

A particularly preferred embodiment of the present invention includes the method described above, characterized in that the compound semiconductor single crystal is a group ■-■ compound semiconductor single crystal, and the liquid metal is a group Regarding single crystals, the use of group Ⅰ elements (for example, Ga for GaAs single crystals and In for InP single crystals) constituting the single crystals as liquid metals is an effective way to increase the purity of the crystals. Particularly preferred in this respect.

[Operation] The present invention will be specifically described below with reference to the drawings. 1st
The figure shows one embodiment of the present invention, and the reference numerals common to those in FIG. 2 or 3 have the same meanings as in FIG. 2 or 3. In the present invention, the only difference from the conventional method is the method of sealing the growth chamber (growth vessel), and the other configurations are as follows.
It is similar to that in FIG.

The characteristics of the present invention are as described above.

The opening has a shape in which the upper end 7 opens outward in a tapered shape, and although the cap 3 and the upper end 7 of the growth vessel are mechanically in close contact with each other, the gas is There is a gap that is small enough to pass through. In this gap, a low melting point metal 8 such as Ga, In, etc. can be placed.

In this state, the raw material polycrystal 2 and the seed crystal 1 are sealed in the growth vessel A1, and a low melting point metal 8, for example, solid In, is placed in the gap between the tapered part 7 of the growth vessel opening and the cap 3. Thereafter, the growth vessel A1 is placed in a furnace, and then the inside of the furnace is evacuated and purged with nitrogen gas. At this time, the inside of the vessel A is also evacuated and purged with nitrogen through a small gap in the cap 3. After the nitrogen purge is completed, first, in order to seal the inside of the growth vessel A, the heater B is heated to melt the low melting point metal 8. When this low melting point metal 8 melts, it enters the minute gap in the cap 3, and the inside of the growth vessel A1 is completely sealed.

Note that since the minute gap is very small, the liquid metal 8 hardly falls into the vessel due to the effect of surface tension.

Next, the high dissociation pressure component 4 is sublimed by heating with the heater C, so that the high dissociation pressure component gas passes through the small through hole 10 and fills the growth vessel A. At this time, the minute gap in the cap 3 is sealed by the liquid metal, so the inside of the growth vessel A is kept very airtight. Therefore, in the present invention, since the vessel can be filled with a high dissociation pressure gas higher than that in the conventional method, a compound semiconductor single crystal can be grown while preventing the high dissociation component from falling out.

The compound semiconductor single crystal produced by applying the method of the present invention is a high dissociation pressure compound semiconductor single crystal, such as GaAs,
GaP, InAs, InP, CdTe
.

Examples include CdHgTe, Zn5e, ZnS, and especially ■
- Group compound semiconductor single crystals, such as GaAs and GaP.

InAs, InP, etc. are preferred. Liquid metals used for sealing against these crystals include GaAs and GaP.
It is preferable to use Ga in cases where the group Ⅰ element is composed of Ca, such as, and In, where the group Ⅰ element is in, such as InAs or InP. This is because if elements different from the constituent elements are used, there is a risk that the Group (1) elements of the seal will vaporize and contaminate the raw material melt. The low melting point metal is melted by heater B, for example, in the case of InP 15
This may be done by heating to a temperature of 6°C or higher, or 30''C or higher in the case of Ga.

As the material of the cap, quartz, impermeable carbon, carbon coated with impermeable carbon, metal, pBN, carbon coated with pBN, etc. can be used.

General conditions other than the sealing method when producing a compound semiconductor single crystal according to the present invention are not particularly limited, and may be any known technique in this type of VGF method.

[Examples] Example 1 According to the present invention, an InP single crystal was grown by the VGF method. In the apparatus configuration shown in Fig. 1, the growth vessel A
, InP polycondensate aloOQg as a raw material.

81.0 g of red phosphorus was charged as a high dissociation pressure component gas raw material, and 10 g of solid In was placed in the gap between the upper end tapered portion of the vessel and the cap. In this state, the growth vessel A was placed in a furnace, and the inside of the furnace was first evacuated to 10-'torr and then pressurized with nitrogen gas. The melting of solid In for sealing is 1
This was done by heating to 80°C. The total pressure of the mixed gas of argon gas and phosphorus gas during single crystal growth is 50 at.
The partial pressure of m% phosphorus was adjusted to 35 atm. The furnace was filled with argon gas at a pressure of about 50 atm to maintain a balance between the inside and outside of the growth chamber. Also, the crystal growth rate is 3III
/h constant. The crystal obtained above has a diameter of 50
It was a perfect single crystal with a length of 110 m1. When the crystal surface was observed, no roughness indicating phosphorus removal, which is seen on the surface of crystals produced by conventional methods, was observed, confirming the effectiveness of the production method of the present invention.

[Effects of the Invention] As explained above, a low melting point metal is placed in the gap between the cap of the present invention and the growth vessel, and after the vacuum sealing in the growth vessel is completed, the low melting point metal is melted to form a microscopic structure in the cap. According to the method of sealing the gap, it is possible to grow the crystal in a state where the high dissociation pressure component gas is filled in the vessel at high pressure. A compound semiconductor single crystal having the same composition can be easily manufactured.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram illustrating an embodiment of the present invention, FIG. 2 is a schematic diagram illustrating the configuration of an apparatus for growing a single crystal by the conventional VGF method, and FIG. 3 is a diagram illustrating the conventional method. In the figure, l is a seed crystal, 2 is a raw material polycrystal, 3 is a cap,
4 is a high dissociation pressure component, 5 is a susceptor, 6 is a crucible, 7 is the upper end of the growth vessel, 8 is a low melting point metal for sealing such as ]n,
9 is a minute hole, IO is a small through hole, A, A, A3 is a growth vessel, B is an upper heater, and C is a lower heater. Figure 1 Figure 2

Claims (3)

[Claims] (1) When growing a compound semiconductor single crystal using the VGF method in a growth chamber filled with a gas containing a high dissociation pressure component of the compound semiconductor single crystal, liquid metal is poured into the gap between the growth chamber wall and the growth chamber sealing cap. 1. A method for producing a compound semiconductor single crystal, characterized by growing the compound semiconductor single crystal by allowing the growth chamber to soak in the growth chamber and sealing the inside of the growth chamber. (2) The method for producing a compound semiconductor single crystal according to claim 1, wherein the compound semiconductor single crystal is a III-V group compound semiconductor single crystal, and the liquid metal is a group III metal. (3) Claim characterized in that the liquid metal is a group III element constituting the group III-V compound semiconductor single crystal (
2) The method for manufacturing a compound semiconductor single crystal according to item 2).