JPH0483793A - Apparatus for vapor growth - Google Patents

Abstract

PURPOSE:To ensure stable feed onto a substrate even for a highly volatile liquid source material by using, as a liquid source storage container, a U-tube with the sectional areas differing from each other at the respective tips and by setting in a vacuum vessel the tube part having smaller sectional area with its neck narrowed down. CONSTITUTION:The tube part having smaller sectional area 11A of a U-tube 11 with the sectional areas differing from each other is inserted into a vacuum vessel 12. And the other tube part with larger sectional area 11B is set outside the vessel 12, and this sectional area is further enlarged to serve this part as a liquid reservoir 13, and a liquid source material 14 such as mercury is put into this reservoir. With the present system, even if said material is highly evaporated in the vacuum vessel 12, such a mercury feed as to keep the liquid level in the reservoir constant will virtually not change the liquid level in the tube part 11A in the vacuum vessel, leading to no variation in the amount of said material evaporated.

Description

[Detailed Description of the Invention] [Summary] Regarding a vacuum evaporation type or hot wall type vapor phase epitaxial growth apparatus, an apparatus in which a predetermined amount of evaporated components of a source material, which is liquid at room temperature, is controlled and supplied to a substrate for epitaxial growth. A vacuum accommodating a substrate, a container for storing a solid or liquid source material containing a component for forming an epitaxial crystal to be formed on the substrate, and a container for storing the substrate and the solid or liquid source material. In an apparatus for heating and evaporating the solid or liquid source material and depositing components of the source material on a substrate to form an epitaxial crystal, the tip part serves as a storage container for the liquid source material. Using U-shaped tubes with different cross-sectional areas, the thin tube section of the U-shaped tube with a small cross-sectional area is squeezed in at least one place and placed in the vacuum container, and the thick tube section of the U-shaped tube with a large cross-sectional area is evacuated. It is constructed by providing a liquid reservoir outside the container and storing a liquid source material in the liquid reservoir.

[Industrial application field]

The present invention relates to a vacuum deposition type or hot wall type vapor phase growth apparatus, and particularly to a vapor phase growth apparatus equipped with a mechanism for supplying a liquid source material.

In recent years, there has been a demand for the development of crystal growth techniques for compound semiconductors that have features that are not found in single semiconductors such as silicon, such as narrow energy band gears, for use as materials for forming photoelectric conversion elements.

Examples of such compound semiconductors include mercury, cadmium, and tellurium (HgCdTe), and mercury, zinc, and tellurium (HgZ).
nTe), gallium aluminum arsenic (GaAl
When growing a material such as As), it is necessary to evaporate a source material such as mercury (Hg) or gallium (Ga), which is liquid at room temperature, as an element constituting the compound semiconductor, and perform vapor phase growth.

It is desired that a predetermined amount of such liquid source material be provided to the substrate.

[Conventional technology]

Conventionally, in such a vacuum evaporation type vapor phase growth apparatus, the method of supplying the basic liquid source material to the substrate is the fourth method.
As shown in the figure, cadmium telluride (
A solid source container 3 containing a solid source material 2 that is solid at room temperature, such as CdTe), and a liquid source container 5 containing a liquid source material 4 that is liquid at room temperature, such as Hg.
Set up.

Then, a substrate 8 for epitaxial growth such as cadmium telluride (CdTe) is placed on a substrate installation stand 7 having a heater 6 facing the storage container 3.5.
, 5, the source material is heated by a heater 9 provided around the
A compound semiconductor crystal of HgCdTe is grown on the substrate in a vapor phase by supplying the evaporated source material components onto the substrate.

[Problem to be solved by the invention]

However, liquid source materials such as HH mentioned above are CdT
The amount of evaporation is usually large compared to a solid source material such as e, and the rate of reduction of the liquid source material is large during the growth process of the epitaxial crystal. If the reduction rate is large in this way, the position of the liquid level of the liquid source material is likely to fluctuate, causing the amount of evaporation to fluctuate, and therefore the amount of liquid raw material supplied to the substrate to fluctuate significantly, resulting in an increase in the amount of epitaxial material that is formed. There is a problem in that the composition varies in the thickness direction of the crystal, making it difficult to obtain an epitaxial crystal having a predetermined composition and thickness.

The present invention solves the above-mentioned problems, and even when using liquid source materials that evaporate rapidly, that is, are rapidly consumed,
The object of the present invention is to provide an apparatus that can stably obtain evaporated components and evaporated amounts, and can stably supply components of a liquid source material onto a substrate.

[Means to solve the problem]

As shown in the principle diagram of FIG. 1, the above purpose is to
The narrow tube part 11A of the tube is squeezed at least in one place and placed inside the vacuum vessel 12 of the vapor phase growth apparatus, and the thick tube part 11B of the U-shaped tube with a large cross-sectional area is expanded and placed outside the vacuum vessel to form the liquid reservoir 1.
3, and a liquid source material is accommodated in the liquid reservoir.

[For production]

As shown in FIG. 1, the apparatus of the present invention inserts into a vacuum container 12 a narrow tube portion 11A having a small cross-sectional area among the U-shaped tubes 11 having different cross-sectional areas. Then, a thick tube portion 11B having a large cross-sectional area of the U-shaped tube is provided outside the vacuum container 12, and the cross-sectional area of this thick tube portion 11B is further expanded to form a liquid reservoir 1.
3, and a liquid source material 14 such as mercury is contained within this liquid reservoir 13.

In this way, based on the same principle as a manometer (pressure gauge), a certain liquid level difference (760 mm if the liquid source material is mercury) can be established between the atmosphere side outside the vacuum vessel and the vacuum vessel side.
) and hermetically sealed.

Furthermore, if a liquid reservoir 13 with a large diameter is provided on the atmosphere side of the vacuum container 12, even if a large amount of liquid evaporates in the vacuum container 12, the liquid level in the reservoir can be kept constant. When mercury is supplied, the position of the liquid level in the thin tube portion 11A within the vacuum container hardly changes, and therefore the amount of evaporation does not change. The amount of change in the position of the liquid level becomes smaller as the cross-sectional area ratio, that is, the aperture ratio, between the narrow tube portion and the thick tube portion increases.

Furthermore, in order to stably supply the evaporated components of the liquid source material to the substrate, the length to maintain a constant liquid level is insufficient;
As shown in the shape of the thin tube part of the U-shaped tube on the vacuum vessel side shown in FIG. It is heated and supplied at a constant temperature.

As shown in the figure, the narrow tube part 118 of the U-shaped tube installed in the vacuum container is squeezed at one or more places, and the narrow diameter part 11 of the U-shaped tube is
C is provided, and the mercury is heated by the heater 15 from the inside or around the tip of the thin tube portion 11A. At this time, the liquid causes convection at the tip of the thin tube section 11A of the U-shaped tube and is kept at a substantially constant temperature, but the convection below is blocked by the narrow diameter section 11C and flows downward. This prevents heat from escaping. Providing a plurality of such narrow diameter portions 11C will further increase the effect.

With this structure, it is possible to always stably supply a liquid raw material source at a temperature close to room temperature on the atmosphere side outside the vacuum container to the vacuum container side at a desired temperature.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail using the drawings.

FIG. 3 shows an embodiment of a hot wall type vapor phase growth apparatus, which is a type of vacuum evaporation apparatus.

In FIG. 3, the liquid source container 16 has a structure similar to that shown in FIG. 1 described above. A solid source container 18 containing a solid source material 17 made of CdTe is provided at the tip of the thin tube portion 11A of this container.

A heater 19 for heating the solid sauce is also provided around the solid sauce container.

In this way, the substrate 21 for epitaxial growth is heated to 180-3
The solid source is heated to a temperature of about 500°C using a heater 19 provided around the container 18, and the heater 15 provided at the tip of the thin tube portion 11A is heated to a temperature of about 200°C. The mercury 14, which is the liquid source material at room temperature, is heated to a temperature of about 100.degree. Even if a liquid source material that evaporates rapidly and is difficult to control is used, an epitaxial crystal of Hg+-xCdx Te with a stable composition and a uniform thickness can be obtained.

Although this embodiment has been described using a hot wall type vapor phase growth apparatus as an example, the present invention can also be applied to a vacuum evaporation type vapor phase growth apparatus such as a molecular beam epitaxial apparatus when using a liquid source material. The device is applicable.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, an epitaxial crystal of a compound semiconductor having a stable composition and a uniform thickness can be obtained even when a liquid source material is used.

[Brief explanation of drawings]

Fig. 1 is a diagram of the principle of the device of the present invention, Fig. 2 is an explanatory diagram of the main parts of the device of the present invention, Fig. 3 is an explanatory diagram of an embodiment of the device of the present invention, and Fig. 4 is a diagram of the conventional device. FIG. In the figure, 11 is a U-shaped tube, 12 is a vacuum container, 13 is a liquid reservoir, 14 is a liquid source material (mercury), 15.19 is a heater, 16 is a liquid source container, and 17 is a solid source material (CdTe).
), 18 is a solid source container, 21 is a substrate, 22 is a substrate installation stand, and 23 is a heater. The first evil

Claims (3)

[Claims] (1) A substrate (21) and a solid containing a forming component of an epitaxial crystal to be formed on the substrate, or a solid or liquid source containing container (18, 16) containing a liquid source material (17, 14); , the substrate (21) and a solid or liquid source container (
18, 16), the solid or liquid source material (17, 14) is heated and evaporated to deposit the components of the source material on the substrate (21). In an apparatus for forming epitaxial crystals, the liquid source container (16) is formed by using U-shaped tubes (11) each having a different cross-sectional area at its tip, and using a narrow tube portion (11A) of the U-shaped tube having a small cross-sectional area. is provided in the vacuum container (12) by squeezing at least one place, and the U having a large cross-sectional area is
The thick pipe part (11B) of the shape pipe is installed outside the vacuum container and the liquid reservoir (1
3) A vapor phase growth apparatus characterized in that a liquid source material (14) is accommodated in the liquid reservoir. (2) Claim (2) characterized in that a heating means (15) is provided at the tip of the thin tube portion (11A) of the U-shaped tube (11).
1) The vapor phase growth apparatus described above. (3) Claim (1) characterized in that the liquid source material (14) is mercury and the vapor phase growth apparatus is a hot wall type vapor phase growth apparatus or a vacuum evaporation type vapor phase growth apparatus.
), or the vapor phase growth apparatus described in (2).