JPH0483791A - Growing method for liquid phase epitaxial crystal - Google Patents

Abstract

PURPOSE:To provide the title growing method so designed that when a thin film crystal is to be grown on a substrate in a vessel, the surface of the bottom of the vessel is made with a material of high affinity for a mother liquor, while the sidewall etc. with another material of low affinity for the mother liquor, thereby effectively preventing such a phenomenon that part of the mother liquor remains in the form of droplets on the crystal grown. CONSTITUTION:A substrate 3 is set in a vessel and a mother liquor 5 for growing is brought into contact with the substrate 3 to effect growth of a thin film crystal 1 on said substrate 3. In this case, the surface facing to the substrate 3, such as the bottom 4 of the vessel is made with a material of high affinity for said mother liquor 5 (e.g. vitreous carbon), while the sidewall 7, substrate holder 6, cover 8, etc., to be eliminated from said mother liquor 5 in its separation from said substrate 3, are made with another material of low affinity for said mother liquor 5 (e.g. boron nitride). Thereby, when the mother liquor 5 is separated from the substrate 3 by tilting the vessel after growing the thin film crystal 1, part of the mother liquor 5 will not remain in the form of droplets 2 on the crystal 1, and, smooth, flat crystal surface can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for growing thin film crystals of compound semiconductors on a substrate by liquid phase epitaxial method.

[Prior Art] Conventionally, containers used when growing thin film crystals of compound semiconductors by liquid phase epitaxial (LPE) methods have been made of quartz glass, carbon, boron nitride, or the like in a single-piece construction. In other words, with quartz glass, all the parts of the container are made from quartz glass, making up the entire container. The materials used are selected based on criteria such as high purity and ease of workability. For example, quartz glass has excellent purity, but it is not used in products with complex structures such as slide boats because they are difficult to work with. In most cases, carbon is used.

[Problem to be solved by the invention] One of the biggest problems when growing thin film crystals using the LPE method is that when the mother liquor is separated from the substrate after the crystal has grown, as shown in Figure 2, the mother liquor 1 to 3 droplets remain on the grown thin film crystal 1. These droplets must not be present when manufacturing devices using this thin film crystal, and engineers are devising various ways to prevent them from occurring (or leaving them behind).

However, there is no superior method, and at most it can only reduce the incidence.

The present invention was made to solve these conventional problems, and when growing thin film crystals by liquid phase epitaxial method, it is possible to smooth and smooth the crystal without leaving a part of the mother liquor on the crystal. The purpose of the present invention is to provide a liquid phase epitaxial crystal growth method that can obtain flat crystal planes.

[Means for Solving the Problems] The present invention relates to a liquid phase epitaxial crystal growth method in which a growth mother liquor is brought into contact with a substrate in a container to precipitate crystals on the substrate to grow a thin film crystal. The opposing surface is formed of a material that has a strong affinity with the growth mother liquor, and the other part of the growth mother liquor when the growth mother liquor is separated from the substrate is formed of a container made of a material that has a weak affinity with the growth mother liquor. This is a liquid phase epitaxial crystal growth method characterized by growing crystals using

[Effect] The operation of the present invention will be explained using the drawings.

First, the reason why the droplets remain on the grown crystal is thought to be as follows. FIG. 3(a) shows the situation immediately after the crystal has finished growing, and the mother liquid 5 is in contact with the bottom 4 of the container at the lower part and the grown crystal 1 and the substrate holder 6 at the upper part. Third
Figures (b) and (C) show the process of separating the mother liquor 5 from the crystal 1, in which the crystal 1 together with the substrate holder 6 is moved in the direction of the arrow. At this time, if the affinity of the mother liquid 5 for the crystal 1 and the substrate holder 6 is greater than or equal to that for the container bottom 4, the adhesiveness becomes stronger for the crystal 1 as shown in (b), and a part of the mother liquid is removed. Drop 2
It will be left as. On the other hand, (C) shows the opposite case, in which the affinity of the mother liquid 5 for the container bottom 4 is greater, so the adhesion to the crystal 1 and the substrate holder 6 is weak, and no droplets are left. To separate.

From the above, it is better to use a material with strong affinity for the bottom of the container, which faces the grown crystals and is in contact with the mother liquor at the same time. on the other hand,
The substrate holder, parts that support the substrate holder, and parts that are separated from the growth mother liquor, such as the wall of the container in contact with the bottom of the container, should be made of a material that has weak affinity or is repellent.

That is, in the present invention, by producing the effect as shown in FIG. 3(C), a thin film crystal can be obtained without leaving any droplets.

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

In this example, a case will be explained in which a thin film crystal of mercury cadmium telluride, which is one of the compound semiconductors, is grown on a substrate made of cadmium telluride by the LPE method.

FIG. 1(a) is a cross-sectional view of an example of a crystal growth container used in the method of the present invention. The bottom part 4 of the container is made of glassy carbon, which has the highest affinity with the growth base material for mercury cadmium telluride (mercury cadmium telluride with a high tellurium content) among easily available materials. , a side wall 7 made of boron nitride, which has low affinity, a substrate holder 6, and a lid 8.

After accommodating the substrate 3 made of cadmium telluride single crystal and the growth base material 5 in this container, as usual, the entire container is vacuum sealed in a quartz ampoule (not shown) and placed in a special electric furnace. A thin film crystal 1 of mercury cadmium telluride is placed on a substrate 3.
Raised above. The growth method is a closed tilting method which is suitable for mercury cadmium telluride among the LPE methods.

The step of separating the mother liquor 5 after the growth step was carried out by tilting the container along with the electric furnace, as shown in FIG. 1(b), which is a side view of the container. In the 6th crystal growth,
Not a single drop remained. If the side wall 7 is made of glassy carbon like the bottom part 4, the mother liquor will enter the gap 9 between the side wall 7 and the substrate 3 by capillary action, and when the crystal is taken out, the mother liquor will be solidified, so that both will be mixed. I got close. Therefore, the only way to remove it was to destroy the substrate and the crystal grown on it.

[Effects of the Invention] As detailed above, according to the method of the present invention, when a thin film crystal is grown on a substrate by a liquid phase method, a part of the mother liquor does not remain on the crystal as droplets, and a smooth surface is formed.・It is possible to obtain a flat crystal surface.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of an example of a crystal growth container in the method of the present invention, Fig. 2 is a perspective view of a thin film crystal when crystal growth is performed according to a conventional method, and Fig. 3 is a thin film crystal after crystal growth is completed. ,
FIG. 3 is an explanatory diagram for explaining the state of the mother liquor and the bottom of the container. 1...Thin film crystal 2...Drop 3...
Substrate 4... Bottom 5... Mother liquid (base material) 6... Substrate holder 7... Side wall
8...Lid 9...Gap between the board and the side wall

Claims (1)

[Claims] (1) In the liquid phase epitaxial crystal growth method in which a growth mother liquor is brought into contact with a substrate in a container and crystals are deposited on the substrate to grow a thin film crystal, the facing surface of the substrate in the container has a high affinity with the growth mother liquor. A solution characterized in that crystal growth is performed using a container made of a strong material, and a separation part of the growth mother liquor when the other growth mother liquor is separated from the substrate is made of a material having a weak affinity with the growth mother liquor. Phase epitaxial crystal growth method.