JPH03183691A - Growing method for single crystal - Google Patents

Abstract

PURPOSE:To prevent base material from remaining as a drop on the surface of grown single crystal and to obtain single crystal consisting of a smooth thin film by obliquely providing a base plate at a specified angle in the case of growing single crystal consisting of the liquid phase epitaxial thin film. CONSTITUTION:In a growing method of single crystal wherein the base material 4 of a raw material is brought into contact with the surface 2a of a downward directed substrate and single crystal consisting of a liquid phase epitaxial thin film is grown, the substrate 2 is titled (e.g. 20 deg.) and provided to the direction of the liquid surface of the base material while single crystal is growing. After growth is finished, the surface 2a of the substrate is separated from the liquid surface 4a of the base material at >=10 deg. angle. The liquid surface 4a of the base material 4 is changed as shown in an arrow as a vessel 1 for growth is transferred to right inclination after growth is finished from a state wherein the vessel 1 is left tilted during growth. when the base material 4 starts to be separated from the substrate 2, it is separated while holding an angle as shown in 4b. Owing to this angle, one part of the base material 4 is not left on the surface 2a of the substrate. Therefore the surface of the grown thin film single crystal is made to a smooth surface on which the base material 4 is not left.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for growing a single crystal, and more specifically to a method for growing a thin film single crystal on a substrate by a liquid phase epitaxial method.

[Prior Art] A method of growing a thin film single crystal by a liquid phase epitaxial method with the substrate surface facing downward has conventionally been carried out as shown in FIG. 2, and this method is called a tilting method. To explain this method based on FIG. 2, first, in FIG. 2(a), a substrate 2 for thin film single crystal growth is placed in a substrate holder 3 with the surface 2a facing downward at one end of a boat-shaped growth container 1. At the other end of the container 1, a raw material base material 4 for thin film single crystal growth is placed. Until the base material 4 melts, it is shown in Fig. 2 (a
), the base metal side is tilted lower, but once it is melted and ready for epitaxial growth, it is tilted so that the substrate side is lower, as shown in Figure 2(b). . Then, the base material 4 is brought into contact with the surface 2a of the substrate 2, and the substrate surface 2a is slowly cooled for a predetermined time.
A thin film single crystal 5 is epitaxially grown on a. After a predetermined period of time has passed and the thickness of the epitaxial crystal 5 reaches a predetermined thickness, as shown in FIG. 2(C), the base material 4 is tilted again so that the substrate side is higher. Let go. This completes the liquid phase epitaxial growth method called the gradient method.

[Problems to be Solved by the Invention] Generally, when trying to grow a thin film single crystal using the method described above, the structure of the growth container and substrate holder is relatively simple so as not to be too troublesome in terms of construction. It is done so that it becomes the shape. That is, in a boat-shaped container, the inner bottom surface is flat, and the substrate holder is necessarily parallel to the bottom surface of the container.
The substrate is then also parallel to the bottom of the container. This means that in the intermediate state when the container changes from a left inclination to a right inclination, for example, when the container 1 is in a horizontal state as shown in FIG. Liquid level 4a
This means that they are in a parallel state.

However, this may cause the problem that when the base material is separated from the substrate after single crystal growth, part of the base material becomes small droplets and remains on the thin film single crystal grown on the substrate. Become. To put this in a simple analogy, when you hold a flat board floating in water horizontally and lift it away from the water surface, it is a spectacular phenomenon where drops adhere to the bottom of the board. It is also a well-known phenomenon that the droplets will move lower depending on the size of the tilt, even if the plate is slightly tilted.

In actual epitaxial growth, the base material has a higher viscosity than water, so even if the substrate and the base material are not parallel at all and are at a slight angle, the drop will remain on the crystal surface. Moreover, as a result of several experiments, it has been found that there is almost no difference in the phenomena that occur whether the amount of base material is large or small. The diameter of these drops is about 50 to 3 mm, the thickness is about 5 to 100 mm, and the number varies from one to several, but in any case, it was an inconvenient phenomenon for device production. .

The present invention was made to solve the conventional problems as described above, and an object of the present invention is to provide a method for growing a single crystal in which the base material does not remain as drops on the surface of the grown crystal.

[Means for Solving the Problems] The present invention provides a method for growing a single crystal in which a liquid phase epitaxial thin film single crystal is grown by bringing the surface of a substrate facing downward into contact with a raw material base material. This single crystal growth method is characterized in that the substrate surface is installed inclined in the direction of the base material liquid level, and after the growth is completed, the substrate surface is separated from the base material liquid level by an angle of 10 degrees or more IEi.

[Function] In the present invention, when the base material and the substrate are separated, they are separated at an angle of 10 degrees or more, and for this purpose, the shape of the substrate holder 13 is changed, for example, as shown in FIG. The substrate 2 is designed to have an inclination angle (for example, 20°) when the substrate 2 is tilted. As a result, the liquid level 4a of the base material 4 changes as shown by the arrow as the container 1 is tilted to the left during growth and tilted to the right after growth, and when the base material begins to leave the substrate. They will move away at an angle like 4b. This angle becomes larger as the rightward tilt becomes stronger. Because of this angle, no part of the base material 4 is left behind on the substrate surface 2a, and therefore the surface of the grown thin film crystal becomes a smooth surface with no base material remaining.

[Example code] Next, embodiments of the present invention will be described in detail.

A compound semiconductor. For the purpose of growing thin film single crystals of , B Cd□, 2 Te, a growth container 1 as shown in FIG. I prepared one tilted at an angle of . A Cd single crystal of 15×15 mm 2 and 1 mm thick was attached as a substrate 2 to this. Base material 4 is 1'
A CdTe compound with an excess of -e is used, and this is 30
9 was used. The procedure for growing a thin film single crystal is the same as the conventional method shown in FIG.

When the single crystal surface was observed after the growth was completed, no drops were observed at all. Six experiments were conducted, all of which were similar. When mounting the board, I tried changing the corners in various ways, but 1
The effect began to appear from 0°, and sufficient effects were obtained from 15 to 20''.

[Effects of the Invention] As explained above, according to the method of the present invention, the base material does not remain in a shell shape on the surface of the grown crystal even when the method is performed with the substrate facing downward in thin film liquid phase epitaxial growth. A smooth thin film single crystal can be obtained.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram for explaining the action of the method of the present invention,
Figure 2 is a process diagram showing a conventional single crystal growth method;
FIG. 3 is an explanatory diagram showing the state when the substrate and base material are separated in a conventional single crystal growth method. 1... Growth container 2... Substrate 2a... Substrate surface 3.13... Substrate holder 4... Base material 4a... Base material liquid level 5... Epitaxial crystal

Claims (1)

[Claims] (1) In a single crystal growth method in which a liquid phase epitaxial thin film single crystal is grown by bringing the substrate surface facing downward into contact with the raw material base material, the substrate is tilted in the direction of the base material liquid surface during single crystal growth. A single crystal growth method characterized in that the substrate surface is separated from the base material liquid level at an angle of 10° or more after the growth is completed.