JPS599515B2 - Liquid phase growth method and equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multilayer liquid phase epitaxial growth method.

The multilayer liquid phase epitaxial growth method is a method mainly used for epitaxial growth of compound semiconductor crystals.

In this method, a solution of molten metal in which crystal constituent elements or compounds are dissolved as solutes is placed in a container made of carbon or the like, and the substrate is slidably displaced toward the bottom of the container. , performing epitaxial growth on the substrate.

Since carbon and the like contain water or oxygen, the water or oxygen diffuses into the solution and reacts with the components of the solution, resulting in the formation of oxides in the parts of the solution that are in contact with the container wall.

Oxides may also be formed on the surface of the solution.

This oxide is generated when the solution comes into contact with oxidizing components such as moisture or oxygen contained in trace amounts in the processing atmosphere, and if this oxide comes into contact with the substrate, overheating may occur. Apart from the cooling step, the tendency of the oxide to solidify on the surface of the substrate or to prevent the contact of the solution with its original composition with the substrate becomes significant.

This causes defects such as uneven crystal growth axes and inclusions.

Therefore, it is an object of the present invention to provide a multilayer liquid phase epitaxial growth method that eliminates these drawbacks.

The method of the present invention includes arranging a semiconductor substrate on a first plate-like body,
The semiconductor substrate is placed on the first plate. A second plate-like body having a plurality of lower through-holes that can be drawn out is disposed, and a second plate-like body is provided with a slit having a width of 1 to 2M and tapered in the direction toward the semiconductor substrate. Arrange the 3 plate-like bodies,
The melt contained in a plurality of ten-holes provided in a fourth plate-shaped body disposed on the third plate-shaped body so as to be slidable with respect to the third plate-shaped body is passed through the slits to melt the semiconductor. A multilayer liquid phase epitaxial growth method for supplying onto a substrate, the second plate-like body and the fourth plate-like body being slid, and the melt contained in the plurality of upper through holes is sequentially passed through the slits. , filling each of the plurality of lower through-holes and performing liquid phase growth, and moving the melt filling the lower through-holes out of the semi-dead substrate region.

Solutions for liquid phase growth include GaAs-Ga based solutions and GaA
lAs-Ga based solutions are mainly used, but since the melting point of the oxides produced from these solutions is higher than the temperature of the solution, the oxides solidify on the container wall, which is the heat transfer surface, and also coat the liquid surface. ing.

Therefore, the entire solution is wrapped in an oxide shell, but when the melt flows out through the slit, if the width of the slit is large, the melt flows through the slit while involving the oxide shell. Pass through.

That is, since the momentum of the melt flow passing through the slit is large, the oxide particles attracted to the wall surface of the container peel off from the wall surface, move toward the inside from the liquid surface, and are caught up in the solution flow.

Therefore, in the present invention, the upper limit of the width of the slit provided in the container is determined so as to stop the inflow of shell oxide once.

On the other hand, as the width of the slit becomes smaller, the influence of the pressure that tries to break the oxide shell and flow into the slit becomes more pronounced, but since the flow velocity of the melt flow becomes smaller, the flow velocity affects the particles of one liquefied material. The tendency for entrainment is reduced, and the tendency of molten metal, which generally has a high surface tension, to flow into the slit due to surface tension is reduced.

The width that allows only the melt surrounded by the oxide shell to selectively flow into the slit is GaAs-Ga based or GaA
For AAs-Ga based melts, 1 to 2M is preferable.

If the temperature of the bath liquid is generally below its primary crystallization temperature, the crystallized solid together with the melt flows through the slit 1.

However, this is not a particular problem, and the present invention provides the slits by paying attention to the fact that the above-mentioned shell-like oxide particles are generated due to a local temperature drop.

In the present invention, the second plate-like body is provided with a plurality of lower through-holes, the fourth plate-like body is provided with a plurality of upper through-holes, and the container formed by the ten through-holes is provided with a multilayer eviximal growth solution. liquid is contained.

During the sliding process, this melt sequentially flows down through the slits into the lower through-hole and fills the lower through-hole.

The melt that fills the lower hole is of the original composition and contacts the substrate there.

The contact liquid filling the lower hole may also be oxidized by oxidizing components contained in the material of the container, but since it does not come into contact with the growth furnace gas, it is not oxidized by the growth furnace gas.

It is desirable that the melt flowing into the lower hole directly collides with the substrate.

After the growth of a given layer is completed, the melt is moved out of the area of the substrate, and the melt for growing the next layer flows down into the empty lower container.

Hereinafter, the present invention will be explained in detail with reference to drawings showing specific examples of the method according to the present invention.

FIG. 1 is a sectional view of a multilayer epitaxial liquid phase growth apparatus, in which a substrate 2 is placed in a region of a first plate-like body 1. As shown in FIG.

A second plate-like body 3 is in contact with the surface of the first plate-like body 1, and this plate-like body has two lower through holes 4a and 4b.

The second plate-like body 3 is in slidable contact with the surface of the first plate-like body 1, and the substrate area is exposed by sliding movement.

The third plate-like body 5 has a bottom surface in contact with the surface of the second plate-like body 3, and this third plate-like body 5 is connected to the first plate-like body 1, and the second plate-like body 5 is connected to the first plate-like body 1. It slides against the body 3.

The third plate-like body 5 is provided with a slit 6 extending vertically, and its sliding causes the slit 6 to open into the lower through-hole 4a or the lower through-hole 4a.
Reach a position where it communicates with b.

In order to minimize the oxidation of the melt that occurs in the slit, it is preferable that the length of the slit 6 is as short as possible.

The width of the slit 6 is preferably tapered in its length direction.

In the illustrated example, the slit 6 is the lower through hole 4 a t 4 b
The upper end of the slit 6 is substantially at the same level as the surface of the third plate-like body 5.

According to a preferred embodiment, the slit is formed from the surface of the oxide formed in contact with the third plate-like body 5 in the ten-part through-hole 8.
If a depression is formed around the slit 6 so that the slit 6 is relatively protruded into a clean solution, most of the shell oxide will remain in the depression. It becomes difficult for such oxides to rise to the slit entrance because it crosses the step between the bottom of the depression and the slit entrance.

The fourth plate-like body 7 has a bottom surface in contact with the surface of the third plate-like body 5.

Two ten-piece through holes 8, 8 are provided in this plate-like body.

In FIG. 1, the two-part through holes 8, 8 are closed by the surface of the third plate-like body 5, so that a container for receiving the melt 9 is created.

The liquid phase growth method using the above-mentioned apparatus is carried out as follows.

A device arranged as shown in Fig. 1 is used to insert the solid material into the upper through-hole 8.
, 8 and heating the entire device, the ten through holes 8 are heated.
Fill 1 with the melt.

The temperature of the melt is then lowered so that the solute crystallizes.

The temperature is lowered by either a known slow cooling method or a temperature difference method.

Next, the plate-like bodies 1 and 5 are slid to the right so that they are arranged as shown in FIG.

The melt 9a flows from the slit 6 toward the container in which the substrate 2 is placed, and fills the container.

At this time, the oxide shell is left in the upper container.

Subsequently, when the plates 1 and 5 are slid to the right, the melt 9b flows into the container on the right and the melt 9a moves out of the area of the substrate.

Due to the contact of the melt with the substrate, crystals of solute components grow epitaxially in multiple layers on the substrate.

According to the present invention, various defects do not occur in the crystal because the substrate is brought into contact with a "clean" solution that does not contain oxides.

By providing two or more through holes in the second and fourth plates, two or more substrates can be processed simultaneously.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a specific example of an apparatus for carrying out the method according to the present invention, and FIG. 2 is the same cross-section as FIG. It is a diagram. DESCRIPTION OF SYMBOLS 1...First plate-shaped body, 2...Substrate, 3.
...Second plate-shaped body, 4...Through hole, 5...
...Third plate-shaped body, 6...Slit, 1...
...Fourth plate-shaped body, 8...Through hole, 9...
- Melt liquid.

Claims (1)

[Claims] 1. A semiconductor substrate is disposed on a first plate-like body, a second plate-like body having a plurality of lower through holes through which the semiconductor substrate can be exposed is disposed on the first plate-like body, and the second plate-like body is disposed on the first plate-like body. On the plate-shaped body, a tapered shape having a width of 1 to 2 ttr in the direction toward the semiconductor substrate.
A third plate-like body having a slit of tll is arranged, and a plurality of plate-like bodies provided on a fourth plate-like body are disposed on the third plate-like body so as to be slidable with respect to the third plate-like body. A multilayer liquid phase epitaxial growth method in which a melt contained in an upper through hole is supplied onto the semiconductor substrate through the slit, the second plate-like body and the fourth plate-like body being slid, and the plurality of upper parts sequentially filling each of the plurality of lower through holes with the melt contained in the through holes through the slits, and performing liquid phase growth; A liquid phase multilayer epitaxial liquid phase growth method, characterized in that the liquid phase multilayer epitaxy is moved outside the semiconductor substrate region.