JPS6021897A - Process for liquid phase epitaxial crystal growth - Google Patents

Abstract

PURPOSE:To improve productivity by eliminating requirement for polishing of a rear face by immersing two substrates joined back to back to each other interposing a spacer therebetween, and performing epitaxial crystal growth simultaneously on only both front surface sides of the two substrates. CONSTITUTION:Both rear faces of two substrates 1 are placed back to back to each other interposing spacers 2 such as graphite spacer or carbon spacer therebetween, and the substrate 1 is held with a substrate holder 3 leaving no gap between the substrate 1 and the spacer 2. Thereafter, the substrate 1 is immersed in immersion soln. to perform epitaxial crystal growth by the immersion method. By this method, epitaxial crystal growth is caused simultaneously on the front surface of two substrates 1, but no epitaxial crystal growth is caused on the rear surface of the two substrates 1. Therefore, the stage for polishing the rear surface of the substrate 1 is eliminated and the productivity is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Background and Objects of the Invention) The present invention relates to a liquid phase epitaxial crystal growth method, and particularly to an improvement of a liquid phase epitaxial crystal growth method using a dipping method.

Conventionally, multilayer crystal growth methods using liquid phase epitaxial methods include methods using a slide boat method and methods using an immersion method. In both of these methods, a temperature difference is created in a melt containing an epitaxial crystal growth substance as a solute, and a compound semiconductor having a composition different from that of the substrate is grown in a single layer or in multiple layers on a substrate using the temperature gradient of the solute. . In this so-called temperature difference method, the growth temperature of each part of the growth layer is always constant, so compared to the cooling method that cools from a supercooled state, it is possible to improve the uniformity of the composition of the grown crystal and the uniformity of the concentration of added impurities. It is possible to obtain a grown layer with excellent crystallinity.

However, on the other hand, the slide boat method is
The disadvantage is that it takes time to cool down the temperature, making it difficult to mass-produce. In addition, although the immersion method is good for mass production, the solution causes epitaxial crystal growth on the back surface of the substrate, which requires two steps to be removed by polishing, etc.
The disadvantage is that there are some inconveniences in the process.

The present invention has been made in view of the above, and its purpose is to provide a liquid layer epitaxial crystal growth method using an immersion method that is suitable for mass production and does not cause epitaxial crystal growth on the back surface of a substrate. It's about doing.

[Summary of the invention]

The feature of the present invention is that in the step of dipping the substrate into the solution, the back surfaces of the substrates are placed back to back to each other, and a spacer is inserted between them to eliminate the gap between the substrate and the spar 1,
The present invention is characterized in that epitaxial crystal growth is simultaneously caused only on the front surfaces of the respective substrates without epitaxial crystal growth occurring on the back surfaces of the respective substrates.

〔Example〕

An embodiment of the method of the present invention will be described in detail below with reference to FIGS. 1 and 2.

FIG. 1 is a configuration diagram showing an example of a support mechanism for a substrate when performing liquid layer epitaxial crystal growth using a liquid layer by immersion according to the present invention, (a) being a front view and (b) a side view.

In Fig. 1, l is a substrate, 2 is a graphite spacer, and 3 is a holder.The back surfaces of the two substrates l are placed back to back, and the graphite spacer 2 is sandwiched between the substrate 1 and the graphite spacer 2. The board is held by the board boulder 3 so that there is no gap between the board and the board.

In the method of the present invention, the structure thus constructed is immersed in a dipping solution to grow epitaxial crystals.

Here is a 55mm x 50mm mirror polished surface.
Two GaΔS substrates with a size of Set up as shown in the figure. This was sequentially immersed in three immersion solutions having different compositions to perform multilayer epitaxial crystal growth. After the crystal growth, when the substrate l was removed from the substrate boulder 3 and observed, the surface of the substrate l had crystal growth with a uniform thickness, but the back surface of the substrate l had no wraparound of crystal growth and was in good condition. A three-layer epitaxial wafer is obtained.

In addition, according to the conventional liquid phase epitaxial crystal growth method using the immersion method, as shown in FIG. GaA with 3000 silicon carbide powder
Epitaxial crystal growth layers 4, 5 on the s-substrate and l-substrate surfaces. ．．
6 had to be removed.

In contrast, according to the method of the present invention, a usable epitaxial wafer with a three-layer structure can be obtained simply by performing liquid phase epitaxial crystal growth.

In the above embodiment, the graphite spacer 3 is used, but a Gargan spacer may also be used, which has good thermal conductivity, is free from contamination of impurities, and is uniform in temperature within the plane of the substrate l. Any material may be used as long as it can improve the purity and purity of the crystal growth layer.

〔Effect of the invention〕

As explained above, according to the present invention, mass productivity is good, and since small crystal growth of Corbitaxy A does not occur on the back side of the substrate, steps such as polishing can be omitted, and productivity is improved. It has the effect of increasing the

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an example of a support mechanism for a substrate when performing liquid phase epitaxial crystal growth by the immersion method according to the present invention, and FIG. FIG. 3 is a cross-sectional view showing a state of crystal growth. l: Substrate, 2 niger roughite spacers. 3: Substrate holder. Look 1 Figure α) Look Z

Claims (1)

[Claims] (1) In a crystal growth method using the immersion method, the back surfaces of the substrates are placed back to back to each other and immersed in a solution with a spacer sandwiched between them, and epitaxial crystal growth is simultaneously performed only on the surfaces of the two substrates that are placed back to back. A liquid phase epitaxial crystal growth method characterized by: