JPS58213416A - Liquid phase epitaxially growing method - Google Patents

Abstract

PURPOSE:To worsen the wetting between a solution and a supporter, and prevent the leakage of the soultion by melting indium on the surface of a substrate supporter and solidifying it and then growing it epitaxially after removing it mechanically. CONSTITUTION:A solution supporter 8 is placed on a substrate supporter 9, and indium 12 and 13 are respectively placed in solution reservoirs 10 and 11. Indiums are melted and then cooled to solidify them. The solution supporter 8 is removed, and the indiums 12 and 13 are mechanically removed. After the removal rough surfaces 14 are formed on the surface of the substrate supporter 9 where the indiums 12 and 13 are removed. When molten indiums are mounted on these rough surfaces 14, they becomes round by their own surface tension. The positional relation between the solution supporter 8 and the substrate supporter 9 is shifted and the above process is repeated.

Description

[Detailed description of the invention] The present invention relates to a liquid phase epitaxial growth method.

As is well known, the liquid phase epitaxial method is one of the effective means for forming an epitaxial growth layer with good crystallinity on a compound semiconductor/conductor substrate such as InP (indium phosphide) or GaAs (gallium arsenide). Industrially very useful devices such as semiconductor lasers have been produced using this liquid phase epitaxy method.

Let me briefly explain the liquid phase epitaxial method. FIG. 1 shows a schematic diagram of a general liquid phase epitaxial growth boat. In FIG. 1, reference numeral 1 denotes a solution support made of graphite, which has holes 4 and 5 for storing the solution. Reference numeral 2 denotes a single-crystal substrate support made of graphite, which entirely holds a single-crystal substrate, for example, an InP substrate 3.

The solution support 1 and the substrate support 2 are formed to slide relative to each other, and have a structure in which the substrate single crystal 3 can be slid so as to be located below the solution reservoir 4 or 5. Here, for example, InP is placed on the InP single crystal substrate 3.
A case will be described in which liquid phase epitaxial growth is performed. 2 in solution reservoir 4? Put In61, solution reservoir 5
Is there an In2 inside? A mixed solution of 7 gold and 30 cm of InP polycrystal was added.

The boat is then heated to 670'C in an H2 atmosphere. Thereafter, the temperature is gradually lowered from 670'C.

When the substrate support 2 is completely slid while the temperature is decreasing so that the single crystal substrate 3 is placed under the solution reservoir 4, the single crystal substrate 3 comes into contact with the In solution 6, so that the temperature of the single crystal substrate 3 is lowered. InP on the surface is melted into the In solution 6 and the surface of the substrate 3 is cleaned. Next, the substrate support 2 is moved so that the single-crystal substrate 3 is under the solution reservoir 5, and the single-crystal substrate 3 comes into contact with the solution. Here, solution 7 is 67
When heated to 0° C., InP dissolves in In and reaches saturation. Thereafter, when the solution 7 is cooled, the solution 7 becomes supersaturated. At this time, melt P2L7 and substrate 3
Since they are in contact with each other, an epitaxial growth layer of InP is formed on the substrate 3. When the epitaxial growth is completed, the substrate support 2 is further moved to separate the substrate 3 from the solution 7, and the epitaxial growth is completed.

In the liquid phase epitaxial growth described above, the substrate support 2
It is necessary to prevent the solution 6 or 7 from leaking from between the solution support 1 and the substrate support 2 when the substrate is slid.

The leakage of solution 6 or 7 is related to the wetting of solution 6 or 7 with solution support 1 and substrate support 2. 7 becomes round due to the surface tension of the solution, eliminating leakage of the solution.

According to experiments by the present inventors, the surface of precisely polished graphite is well wetted with the In solution, and if a gap is created between the solution support 1 and the substrate support 2, the solution 6 or 7 may leak. , and the substrate 3 after epitaxial growth.
There was some In remaining on the surface.

The present invention was made to eliminate such solution leakage during epitaxial growth of InP by roughening the surfaces of the solution support 1 and the substrate support 2 in contact with the solutions 6 and 7. The present invention provides a method for treating a liquid phase epitaxial growth boat that improves wetting of the solutions 6 and 7 with the supports 1 and 2 and eliminates leakage of the solutions 6 and 7.

The inventors put fni on top of graphite, heated and melted it, cooled it and solidified it, and recalled that the surface of graphite, which was roughened by mechanically peeling it off from k-graphite, had poor wettability with In solution. The present invention has been made based on this recognition.

Embodiments of the present invention will be explained below.

FIG. 2 shows a method according to an embodiment of the present invention. As shown in FIG. 2a, a graphite solution support 8 is placed on a graphite substrate support 9, and In 12 and 13 are placed in solution reservoirs 10 and 11 in an atmosphere of, for example, H2 or an inert gas. After melting Ini at 720'C, it is cooled to completely solidify In.

Next, when the solution support 8 is removed, the solidified In 12 and 13 are adhered to the substrate support 9 as shown in FIG. If In 12 and 13 are mechanically removed using, for example, tweezers, rough A14 will be formed on the surface of the substrate support 90 in the area where In 12 and 13 have been removed, as shown by the dotted line in FIG. If the situation deteriorates and the In melt for growth gets on this part, the In melt will become rounded due to the surface tension of the In melt itself. Next, by repeating the above process with the positional relationship between the solution support 8 and the substrate support 9 shifted from that shown in FIG. All parts of the surface of the substrate support 90 that come into contact with the In solution can be roughened.

By performing the surface treatment of the substrate support 9 as shown in the embodiment of the present invention, the In solution becomes rounded by the surface tension of the In solution itself during liquid phase epitaxial growth, so that leakage of the In solution is eliminated. No more In remains on the substrate surface after InP epitaxial growth.

FIG. 3 shows another embodiment of the invention. As shown in FIG. 3a, during liquid phase epitaxial growth, In15 is applied to the entire area where the graphite substrate support 9 and the In solution come into contact.
A solution support 17 having a solution reservoir 16 on which In15i is placed is prepared, and In15i is melted at 720° C. in an atmosphere of H2 or an inert gas, for example, and then cooled and In15i is melted.
Solidify n15. Next, when the solution support 17 is removed, the result is as shown in FIG. When In 15 is mechanically removed, the substrate support 1 is removed as shown by the dotted line in FIG. 3C.
The surface of 5 can be roughened.

The other embodiments of the present invention described above are characterized by using a solution support having a solution reservoir such that In is deposited on the entire portion where the substrate support and the In solution come into contact during liquid phase epitaxial growth. The surface of the substrate support can be treated by melting In once.

As explained above, by applying the surface treatment of the present invention, leakage of In solution during liquid phase epitaxial growth and In remaining on the substrate surface after epitaxial growth are eliminated, which greatly contributes to liquid phase epitaxial growth.

[Brief explanation of the drawing]

Figure 1 is a schematic cross-sectional view of a liquid phase epitaxial growth boat.
Figures 2a-d are schematic cross-sectional views of a surface treatment method for a liquid phase epitaxial growth boat according to an embodiment of the present invention, and Figure 3a'
%-C is a schematic cross-sectional view of the same surface treatment method according to another embodiment of the present invention. 8.17...Solution support, 9...Substrate support, 10.1'1.16...Solution reservoir, 1
2,13゜15...In0

Claims (2)

[Claims] (1) Melting indium on the surface of a substrate support of a liquid phase epitaxial growth boat, solidifying the indium, mechanically removing the indium, and then epitaxially growing the substrate on the substrate support. A liquid phase epitaxial growth method characterized by having all the steps of performing. (2) The solution according to claim 1, characterized in that indium is melted using a solution support such that indium is deposited on the entire surface of the substrate support in the portion that comes into contact with the solution during liquid phase epitaxial growth. Phase epitaxial growth method.