JPS5932052B2 - Liquid phase epitaxial growth method and its growth device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid phase epitaxial growth method using a high frequency induction heating method and a growth apparatus therefor.

The liquid phase epitaxial growth method is a method widely used for growing compound semiconductor epitaxial layers.
This is an indispensable method for the epitaxial growth of -V compound semiconductors.

In this method, a resistance heating method is used as a heating means for heating and slowly cooling a melt to grow an epitaxial layer on a semiconductor substrate. FIG. 1 shows, for example, a GaP substrate 3 installed in a quartz tube 2 installed in an electric furnace 1 5 using a conventional resistance heating method, and a growth boat 6 filled with a gallium Ga solution 4 placed across a partition plate 5. The molten liquid 4 heated by the electric furnace 1 is moved by moving the partition plate 5 by operating the operating rod □, and is filled into the GaP substrate installation part in the lower part 0, and the GaP substrate 3 is heated.
After sufficient contact with the GaP substrate 3, the temperature is gradually lowered to grow an epitaxial layer on the GaP substrate 3.

Incidentally, in liquid phase epitaxial growth, growth is efficiently performed under a so-called temperature gradient in which the temperature of the surface of the five substrates is set slightly lower than the temperature of the melt.

However, in the resistance heating method, which heats the entire inside of the furnace, it is difficult to create a delicate temperature gradient as described above because the entire quartz tube is heated. In addition, this method uses an electric furnace, which has a very large heat capacity, takes a long time to heat and cool, and requires a long recycling time.Furthermore, heating of quartz tubes, etc. that are unnecessary for growth is unavoidable, and contamination with impurities is avoided. There were some drawbacks such as 5.

The present invention aims to efficiently obtain a good epitaxial growth layer under a temperature gradient by introducing a high frequency induction heating method in place of the conventional resistance heating method.

Next, a liquid phase epitaxial growth apparatus according to an embodiment of the present invention and a liquid phase epitaxial growth method using the same will be described with reference to the drawings.

As shown in FIG. 2, the liquid phase epitaxial growth apparatus of the present invention includes a quartz tube 1 having a heating coil 11 on its outer periphery.
A growth boat 16 is installed inside the tank 2.

The growth boat has an operating rod 17 made of alumina ceramic.
Through the partition plate 15 that can be opened and closed by
A liquid tank filled with a Ga solution 14 containing dissolved Ga and a growth tank are arranged below.
P substrates 13 are supported in close contact with each other, and these are placed perpendicularly to the bottom surface of the boat at regular intervals, and a heated body 19 made of graphite is placed between them. Here, the alumina ceramic of the support plate 18 was selected as a material that is difficult to be heated by induction, and other materials such as quartz glass may also be used.

On the other hand, graphite as the object to be heated 19 is selected because it is easily heated by induction, and other materials may be used as long as it is easily heated by induction. Materials for the partition plates and growth boats can be selected according to needs. In performing liquid phase epitaxial growth using the above-mentioned apparatus, first, GaP is dissolved as a solute in gallium as a solvent, and the sufficiently melted molten liquid 14 is placed in the liquid bath of the growth boat 16 and placed in a quartz tube. Install it at the specified location.

Next, a high frequency voltage is applied to the heating coil 11 to control the temperature of the melt to 1050°C, and then the operating rod 1
7, remove the partition plate 15 and pour the melt 14 into the growth tank.
is filled and brought into sufficient contact with the GaP substrate. At this time, the heated body 19 in the growth tank is also induction heated and becomes a heat generating body. While controlling the applied output in this way, the melt is gradually cooled down to 900° C. at a rate of 5° C./min and then gradually removed. In this case, a temperature difference ΔT as shown in FIG. 2 occurs between the heated body portion 19 and the support plate 18 portion.

At this time, it is desirable to set the temperature to about ΔT-10.
By using such a device and method, it is now possible to easily lower the temperature of the substrate side than the temperature of the melt, which was difficult with conventional resistance heating methods, and the temperature difference can be freely controlled. Therefore, precipitation from the melt occurs preferentially on the substrate side, and epitaxial growth is performed under a so-called temperature gradient, making it possible to perform epitaxial growth with high growth efficiency. Furthermore, since unnecessary parts such as the quartz tube are not heated, impurities are less likely to be mixed into the growth layer, and the time required for heating and cooling is shortened, resulting in a significant reduction in cycle time. In addition, although we have described here the epitaxial growth method using the so-called slow cooling method, which performs growth by slow cooling, by selecting the setting conditions, it is also possible to perform so-called constant-temperature liquid phase epitaxial growth, that is, growth using the temperature difference method. It is.

Here, we have talked about the board arranged vertically, but
A horizontal arrangement may be used, or when it is necessary to form epitaxial layers on both sides of the substrate, the support plate 18 may be removed, and the substrate may be fixed at the bottom of the growth tank, for example, and the substrate and the object to be heated may be arranged alternately. do it.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram of a conventional liquid phase epitaxial growth apparatus.
FIG. 2 is a block diagram of a liquid phase epitaxial growth apparatus according to an embodiment of the present invention. 1... Electric furnace, 2... Quartz tube, 3...
...Semiconductor substrate, 4...Solution, 5...
・・Partition plate, 6・・Growth boat, 7・・・・
・Operation rod, 11...Heating coil, 12...
...Quartz tube, 13...Gallium phosphide substrate, 14
...Gallium phosphorous solution, 15...
...Partition plate, 16...Growth boat, 17...
...Operation rod, 18...Support plate, 19...
... Heated object.

Claims (1)

[Scope of Claims] 1. In order to grow an epitaxial layer by bringing a melt into contact with the surface of a semiconductor substrate placed in a boat for liquid phase epitaxial growth, induction heating is performed at a predetermined distance from the semiconductor substrate. A liquid phase characterized in that a temperature difference is formed in the molten liquid between a surface portion of the heated object and a surface portion of the semiconductor substrate by arranging objects to be heated that are easily heated in parallel and performing high-frequency heating. Epitaxial growth method. 2. A quartz tube having a high-frequency heating source on the outside, and a boat for epitaxial growth installed in the quartz tube, and a semiconductor substrate for growth placed in the boat and a predetermined amount of semiconductor substrates in the same placement section. A liquid phase epitaxial growth apparatus characterized in that objects to be heated that are easily induction heated are arranged in parallel at a distance apart. 3. The liquid phase epitaxial growth apparatus according to claim 2, wherein the semiconductor substrate placement portion is made of a semiconductor substrate support plate that is not easily subjected to induction heating.