JPH02129093A - Crystal growth equipment for Group 2-6 compound semiconductors - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a crystal growth apparatus, and particularly to a crystal growth apparatus for It-VI group compound semiconductors.

[Prior Art J] Conventionally, vapor phase crystal growth of -vl group compound semiconductors using halogen gas is known. This example is shown in Figure 2 (A).
Shown in (B).

As shown in FIG. 2(A), a source crystal powder 23 and a halogen 25 such as iodine as a transport agent are placed in the lower part of a quartz ampoule 21, and a taper (θ=60 to 70
°C), a sheet crystal 27 and a quartz rod 29 were placed thereon, and vacuum sealed.

This growth ampoule is placed vertically in a vertical furnace having a predetermined temperature distribution, and the temperature distribution is set as shown in FIG. 2(B). Convective diffusion occurs due to the temperature difference, and the following reactions occur in the high temperature and low temperature areas.

High jm: RIIRVI 10X 2→RIIX2+1
/2Rv■2 low; Akira: RriRV, +X2←RrLX2
+1/2 Rv.

R... Group VI atom] R... Group VI atom ■ X... Halogen atom This reaction causes halogenation of the source material in the high temperature area, and the source material is precipitated again in the low temperature area to generate halogen gas. In this way, the vapor pressure of the constituent elements is controlled, and high-purity, high-grade materials are transported.
A crystal-grown ■-■ group compound semiconductor crystal is formed on the sheet crystal by vapor phase growth.
An object of the present invention is to provide a crystal growth apparatus.

[Problems to be Solved by the Invention] According to the prior art as described above: (1) Since halogen such as iodine is used as a transport agent, it is taken in at a high concentration during crystal growth, resulting in high purity crystals. (2) Also, since a large amount of iodine with a high vapor pressure is put into the ampoule, the vapor pressure inside the growth container during growth is high and there is a risk of the ampoule exploding (3). , in order to put a large amount of iodine with high vapor pressure into the ampoule,
Since the vapor pressure of the constituent elements cannot be controlled, there is a large deviation from the stoichiometric composition, making it impossible to grow high-quality crystals.

An object of the present invention is to provide a crystal growth apparatus capable of vapor-phase growth of high-purity, high-quality compound semiconductor crystals of the ■-■ group without using halogen for transportation.

Another object of the present invention is to provide a high-temperature chamber and a low-temperature chamber that are effectively connected to each other through a region having a small cross-sectional area. A source crystal of a ■-■ group compound semiconductor is placed in the cold room, a heat sink is placed in the low temperature chamber, and a sheet crystal of a ■-■ group compound semiconductor is placed on top of the heat sink, and the effective cross-section is further placed in a tube with a small effective cross-sectional area. A ■-■ group compound semiconductor crystal growth apparatus that is connected to a small stacked area, has a vapor pressure control chamber containing a vapor pressure source containing constituent elements of a II-Vt group compound semiconductor, and is sealed in a vacuum.

[Operation] Since the If-Vt group compound semiconductor is sealed in a vacuum without using halogen gas, the crystal of the U-Vt group compound semiconductor grows without incorporating a halide.

Since halogen, which has a high vapor pressure, is not used as a transport agent, the pressure inside the angle during crystal growth can be reduced.

Crystals grow on sheet crystals due to concentration diffusion due to temperature gradients. Further, source atoms supplied in the gas phase migrate on the sheet crystal, thereby growing an epitaxial crystal.

In addition, by connecting a vapor pressure control chamber to a region with an effectively small cross-sectional area at the top of the sheet crystal chamber, it is possible to directly apply the vapor pressure of the constituent elements to the crystal growing in the sheet crystal chamber. The vapor pressure can be controlled by controlling the deviation from the stoichiometric composition.

[Example] Figures 1A and 1B show schematic diagrams of a crystal growth apparatus 1 of the present invention. chamber 3, sheet crystal chamber 5 in which sheet (seed) crystal 4 is arranged, II-V
It has a vapor pressure control chamber 7 in which a vapor pressure source 6 of a constituent element or its compound of a T-group compound semiconductor is disposed, and a source crystal chamber (high temperature chamber) 3 and a sheet crystal chamber (low temperature chamber) 5 are arranged with quartz in between. They are connected by a space 11 having an effectively small cross-sectional area formed by inserting a solid rod 9.

A material with high thermal conductivity such as carphone, PBN, quartz, etc. is arranged as a heat sink 13 in the lower part of the sheet crystal chamber 5, and the sheet crystal 4 is arranged thereon. A cylindrical quartz tube is placed on top of the sheet crystal 4 as a sheet crystal stopper 17 to ensure that the sheet crystal 4 is in close contact with the heat sink 13.

Furthermore, a vapor pressure control chamber 7 is provided which is connected to a region 11 of an effectively small cross-sectional area in the upper part of the sheet crystal chamber (low-temperature chamber) 5 by a pipe 8 of an effectively small cross-sectional area.

A temperature distribution as shown in FIG. 1(B) is set in this crystallization apparatus 1. The source crystal 2 is maintained at a source temperature T1 and generates a constant raw material vapor pressure. The constituent elements or their compounds 6 are kept at the vapor pressure source temperature T2, and the vapor pressure of the constituent elements is supplied to the source crystal chamber 3. Here, TI > T2, and by adjusting the temperature of the vapor pressure control chamber 7. The vapor pressure of the constituent elements within the sheet crystal chamber 5 can be controlled. The sheet crystal 4 is maintained at a crystal growth temperature T3 where TI>T3.

The gas phase material transported from the source crystal chamber 3 grows epitaxially on the sheet crystal 4. By effectively connecting the vapor pressure control chamber 7 to a region with a small cross-sectional area through a thin pipe 8 and adopting a structure in which vapor pressure control components can be directly supplied to the crystals growing in the sheet crystal chamber 5, crystals can be grown. By controlling the vapor pressure during growth, we were able to control the stoichiometric composition of the grown crystal.

Crystal growth using this apparatus will be explained using ZnSe as a representative example of an n-vi group compound semiconductor.

Slicing, lapping, polishing and chemical etching were performed as a sheet crystal 4 on the heat sink 13 at the bottom of the quartz angle 10 having the structure shown in FIG. 1(A).
The sheet crystal 4 is fixed with a cylindrical quartz tube 17. Further, as a vapor pressure source 6, Zn or Se, which is a constituent element of Zn5e, is introduced into the vapor pressure control chamber 7. A recess 18 for supporting the spacer 9 on the sheet crystal chamber 5 of the angle body
A solid quartz rod is inserted as a spacer 9, and a region 11 with an effectively small cross-sectional area is created around it. A Zn5e polycrystal synthesized at a temperature lower than the growth temperature, for example, a CVD polycrystalline ingot, was placed on the spacer 9 as the source crystal 2, and sealed under a high vacuum of, for example, 10-67° r.

This growth ampoule is vertically placed in a vertical furnace having a predetermined temperature distribution as shown in FIG. 1(B). When each part of the ampoule reaches a predetermined temperature, the vapor evaporated from the source crystal 2 in the source crystal chamber 3 constitutes the primary raw material gas, and is effectively supplied to the sheet crystal chamber 5 through a region with a small cross-sectional area. .

On the other hand, the controlled vapor pressure is effectively supplied from the vapor pressure control chamber 7 to a region 11 having a small cross-sectional area, and together with the above-mentioned primary material gas, forms material waste having a desired configuration.

The sheet crystal 4 is set at a lower temperature than the source crystal 2 so that the raw material gas is transported by the temperature difference, and receives the raw material gas supplied through the narrow region 11 to cause epitaxial growth.

In this way, the source material is transported in a vapor phase from the high temperature chamber (source crystal chamber) 3 to the low temperature chamber (sheet crystal chamber) 5 via the area 11 with a small cross-sectional area due to the temperature difference under vapor pressure control. be done. The sheet crystal 4 is thermally cooled by the heat sink 13, and the crystal grows thereon.

The growth rate depends on the growth temperature T3 and the temperature difference ΔT=TIT3, but for example, if the growth temperature is 950°C5 and the temperature difference is 50°C.
A growth rate of about 10 μm/hr can be obtained.

FIG. 3 shows an embodiment of the pond of the present invention. The diameter of the ampoule 10 is increased on the spacer 9, and the source crystal chamber 3 is wide.
is ensured. In addition, the vapor pressure control chamber 7 is the heat sink 1
It is placed below 3.

As an example of one structure, the height hl of the main ampoule 10 is approximately 240 mm.
~250nn, and the height h2 from the bottom of the main ampoule 10 to the top surface of the spacer 9, that is, the source crystal chamber 3, is approximately 2001 nm.
111, the height h3 of the carbon heat sink 13 is approximately 1
0011, the thickness d of the spacer 9 is about 40-501I. The diameter of the wide part of the upper source crystal chamber 3 of the main angle 10 is 121nφ, and the diameter of the narrow part below the spacer 9 is 811nφ.
φ, and the diameter of the pipe 8 with a small cross-sectional area is 3.5+11φ,
The diameter of the vapor pressure control chamber 7 is 5Ill■φ. Approximately 1-4g
Source crystal 2 with a diameter of 8111φ and a thickness of 0.5 to 1.01 mm.
1 sheet crystal 4 is introduced, the temperature T1 of the source crystal 2 is set to 1000 to 1100°C, and the growth temperature T3 is set to 900 to 100°C.
A grown crystal with a diameter of 8 nmφ and a thickness of 10 to 1511 mm was obtained by controlling the temperature T2 of the vapor pressure source to 500 to 600°C at 0°C.

Note that an impurity may also be introduced into the vapor pressure control chamber 7 to grow an impurity-doped crystal.

FIGS. 4(A) and 4(B) show examples of the vapor pressure dependence of the growth rate. FIG. 4(A) shows the case of non-doping, and the growth rate decreases as the zinc pressure pzn increases. 4T
Below Orr, the rate drops to about 2 μm/hr or less. Figure 4 (
B) shows the case of In doping.

In the case of 1n dope, the growth rate decreases as the zinc pressure increases, as in the non-doped case, but the absolute value of the growth rate is about one order of magnitude lower.

Although the above explanation has been made using Zn5e as an example, it goes without saying that the present device can also be applied to other group compound semiconductors.

That is, 1nS, which has properties similar to 1nSe,
It is possible to grow crystals of CdS, 2nTe, CdSe, etc. using the same growth principle. Note that as the vapor pressure control element, any constituent element can be used as appropriate for the desired electrical conductivity type.

Although growth using a vertical furnace is shown, a horizontal furnace may also be used.
That is, a furnace having a horizontal temperature distribution is constructed, and a horizontally long ampoule is inserted into the furnace. Inside the ampoule,
The source crystal chamber, which is a high temperature chamber, and the sheet crystal chamber, which is a cold chamber, are connected side by side through a narrow connection section, and the vapor pressure control chamber is connected to the narrow connection section through a thin pipe, as described above. Same as the example.

In the above-described embodiment, the vapor pressure control chamber is placed on the lower temperature side than the connection point of the area 11 having an effectively small cross-sectional area, but it may be placed on the high temperature side. Also, once the angle is set in the furnace, it will not move during crystal growth.

[Effects of the Invention] Since the atmosphere in which the source material is transported to the sheet crystal is vacuum and does not contain a transport medium such as halogen, a high-purity, high-quality crystal can be obtained.

In addition, the pressure during growth is low and the risk of ampoule explosion is low.

Since the high temperature chamber and the low temperature chamber are effectively connected by a connection having a small cross-sectional area and are thermally separated, the composition of the constituent elements of the source material can be easily controlled during crystal growth.

[Brief explanation of the drawing]

FIGS. 1(A) and (B) show 1l-V according to an embodiment of the present invention.
2 shows a crystal growth apparatus for group I compound semiconductors, (A) is a schematic cross-sectional view, (B) is a temperature distribution diagram, and FIGS. 2 (A>, (B) are conventional If-VI group 1 compound semiconductors (A> is a schematic cross-sectional view, (B) is a temperature distribution diagram, and FIG. 3 is a schematic cross-sectional view of a crystal growth apparatus for a II-VI group compound semiconductor according to another embodiment of the present invention. Figure 4 (A), (
B) is a graph showing the In pressure dependence of the growth rate in non-doped and In-doped cases. Spatial heat sink with spacer small cross section

Claims (1)

[Claims] (1) A high-temperature chamber and a low-temperature chamber are effectively connected through a region with a small cross-sectional area, a source crystal of a II-VI compound semiconductor is placed in the high-temperature chamber, and a heat sink is provided in the low-temperature chamber. A sheet crystal of a II-VI group compound semiconductor is placed thereon, and a tube with an effectively small cross-sectional area is connected to the area of the effectively small cross-sectional area, and the constituent elements of the II-VI group compound semiconductor are placed on top of the sheet crystal. 1. A crystal growth apparatus for a group II-VI compound semiconductor, characterized in that it has a vapor pressure control chamber containing a vapor pressure source containing a vapor pressure source, and is sealed in a vacuum.