JPS61108131A - Crystal growth method - Google Patents

Abstract

PURPOSE:To make it feasible to control a thin epitaxial layer to be grown by a method wherein the crystal growing thickness of one substrate is made larger than that of the other substrate among two opposing semiconductor substrate. CONSTITUTION:Solution of As 13 saturated with Ga 12 is permeated into the gap between two opposing substrates 9, 10 to slowly cool down the temperature of furnace for resultant epitaxial growing of GaAs on the substrates 9, 10. At this time, the plane directions of substrates 9, 10 are respectively set up to be (2-21) plane and (001) plane while the gap between substrates 9 and 10 is set up not to exceed the diffusion length of solute. Thus a thick GaAs crystal layer 16 may be grown on the substrate 9 while a thin GaAs crystal layer 17 may be grown on the substrate 10 since the growing speed on the (2-21) plane is around three times of that on the (001) plane. Through these procedures, the thin layer 17 may be controlled to be grown by means of selecting said plane directions.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for growing semiconductor crystals by liquid phase growth.

[Conventional technology]

In general, a liquid phase growth method is well known as a means of manufacturing semiconductor crystals, particularly 1-V group compound semiconductor crystals. This liquid phase growth method involves bringing a semiconductor substrate into contact with a saturated melt obtained by heating and melting a semiconductor material, cooling the saturated melt, and epitaxially growing the semiconductor material in the melt onto the surface of the semiconductor substrate. It is something.

Conventionally, various apparatuses have been proposed as apparatuses for carrying out liquid phase growth, and one example is a liquid phase growth apparatus as shown in FIG. That is, in the figure, 1 is a melt, for example GaAs.

In the case of liquid phase growth, a Ga solution is saturated with As and impurities are added thereto. 2 is a container in which the melt 1 is placed; 3 is a lid member that has no gap with respect to the container 2 and is slidable downward;
4 a pressing jig for sliding the bottom lid member 3 downward;
5 is a growth melt tank, 6 is an inlet slit for introducing the melt 1 into the growth melt tank 5, 7 is an exit slit corresponding to the inlet slit 6, and 8 is the melt pressed from the growth melt tank 5. 9 is one of the semiconductor substrates set in the growth melt tank 5; 10 is the other semiconductor substrate disposed facing the one semiconductor substrate 9; 11 is the growth melt tank 5; Melt tank5. This is a holding member for holding the melt reservoir tank 8 and the semiconductor substrates 9 and 10, and is configured to interlock with the pressing jig 4. Moreover, the container 2 contains the melt 1 and the lid member 3.
It is also configured so that it can be moved in the left and right directions in the figure by external operation.

When performing actual epitaxial growth using the liquid phase growth apparatus configured as described above, first, as shown in the figure, a melt 1. The boat containing the lid member 3 and the semiconductor substrates 9 and 10 is inserted into a furnace (not shown) heated to a growth temperature. After holding these for a certain period of time, the container 2 is moved to the right side in the figure by an external operation. that time,
The lid member 3 on the melt 1 is pressed by the pressing jig 4, and the melt 1
is introduced into the growth melt tank 5 through the inlet slit 6.

The introduced melt 1 flows between and comes into contact with one semiconductor substrate 9 and the other semiconductor substrate 10 facing each other with a certain gap therebetween. By gradually cooling the temperature of the furnace from this state, epitaxial growth is performed on the semiconductor substrates 9 and 10.

Furthermore, when epitaxially growing layers with different impurities or different materials, by moving the container 2 further to the right, the melt 1 with the next composition is pushed by the pressing jig 4, and the melt 1 is pressed by the pressing jig 4. The liquid 1 is introduced through the inlet slit 6 in a trickling manner, displacing the previous melt 1.

FIG. 5 shows GaAs semiconductor substrates 9 facing each other in this way,
This figure shows a model in which a GaAs crystal grows epitaxially from a saturated As13 melt in Ga12 introduced over a period of 100 minutes. That is, as shown in the figure, Ga1
By gradually cooling the temperature of the furnace, the As 13 saturated in 2 is formed into GaAs crystal layers 14 and 15 on the opposing surfaces of one GaAs semiconductor substrate 9 and the other GaAs semiconductor substrate 10.
are epitaxially grown.

[Problem that the invention seeks to solve]

However, in the conventional semiconductor crystal growth apparatus configured as described above, the growth rate is approximately determined by the height of the melt 1 that contacts the semiconductor substrate, that is, the absolute amount of the melt 1 that contributes to epitaxial growth. , it has been almost impossible to controllably grow even thinner epitaxial layers.

Therefore, the present invention was made in view of the above-mentioned drawbacks of the conventional technology, and its purpose is to provide a crystal growth method that can control and grow an extremely thin epitaxial layer using liquid phase growth. There is a particular thing.

[Failure to solve the problem]

In order to achieve such an object, the present invention has an object in which, when performing crystal growth, the amount of crystal growth on one of two semiconductor substrates facing each other is compared with the amount of crystal growth on the other semiconductor substrate. It is meant to be larger than that.

(Operation) In the present invention, since the magnitude of the crystal growth rate is different for each plane index of the semiconductor substrate, the amount of crystal growth is controlled.

Further, in another invention of the present invention, by increasing the surface area of one of the two semiconductor substrates facing each other, a crystal layer [Example] will be described below with reference to the drawings. Examples of the invention will be described in detail.

FIG. 1 is a graph showing the surface index and growth rate of a blank semiconductor substrate for explaining one embodiment of the crystal growth method according to the present invention. As shown in the figure, the plane index of the commonly used semiconductor substrate is the (001) plane.
The growth rate on the (331) surface is approximately 'A' on the (221) surface.
It is about + of the surface.

Figure 2 shows two GaAs semiconductor substrates 9 facing each other.
This figure shows the epitaxial growth of GaAs crystal layers 16 and 17 from the A813 saturated melt in Ga12 introduced during .

Next, the crystal growth method according to the present invention will be explained based on these figures. First, using the semiconductor crystal growth apparatus explained in FIG. Cool the temperature gradually. This allows G
Supersaturated As1 on the aAs semiconductor substrate 9°10
3 is epitaxially grown as GaAs. At this time, the plane orientation of one semiconductor substrate 9 is set to the (221) plane, and the plane orientation of the other semiconductor substrate 10 is set to the (001) plane, and the distance between both semiconductor substrates 9 and 10 is set to allow diffusion of solutes. In other words, in the case of GaAs, the diffusion length is set to 1.5 plates or less, which is narrower than the diffusion length of A8. As a result, the growth rate on the (221) plane of one semiconductor substrate 9 is about three times that of the growth rate on the (001) plane of the other semiconductor substrate 10, as explained in FIG. As shown in FIG.
) plane, resulting in a thick GaAs crystal layer 16, and as a result, a thin GaAs crystal layer 17 is grown on the (001) plane of the other semiconductor substrate 10.

By selecting the (001) plane as the plane orientation of the other semiconductor substrates 10 facing each other in this way, it is possible to control and grow the thin GaAs crystal layer 16 using the liquid phase growth method. Become.

FIG. 3 is a sectional view of two semiconductor substrates facing each other for explaining another embodiment of the present invention, and the same parts as in FIG. 2 are given the same reference numerals. In the figure, one of the semiconductor substrates facing each other, 9', has its surface roughened to increase its surface area. As a result, the amount of growth of the GsLAs crystal layer 14' on the semiconductor substrate γ whose surface area has been increased by processing the uneven surface is larger than that on the flat surface, so that the supersaturated As13 grows on the surface processed with the uneven surface. As a result, the GaAs crystal layer 17 on the flat surface of the other semiconductor substrate 10 becomes thinner.

〔Effect of the invention〕

As explained above, according to the present invention, the growth rate of one of the semiconductor substrates facing each other is made faster than the growth rate of the other semiconductor substrate, which is impossible with conventional liquid phase growth methods. The extremely excellent effect of being able to control the growth of a thin growth layer, which has previously been achieved, can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between the plane index of a GaAs substrate and the growth rate to explain an embodiment of the crystal growth method according to the present invention, and FIG. 2 shows an embodiment of the crystal growth method according to the present invention. FIG. 3 is a diagram of the crystal growth principle showing another embodiment of the crystal growth method according to the present invention.
FIG. 4 is a sectional view showing a liquid phase growth apparatus, and FIG. 5 is a diagram showing the principle of conventional crystal growth. 1... Melt, 2... Container, 3... Lid member,
4...Press jig, 5...Growing melt tank, 6...
・Entrance slit, 7...Exit slit, 8・O...
Melt reservoir tank, 9.9', 10... semiconductor substrate, 11
...Holding member, 12...Φ・Ga113...A
Bl 14,14', 15°16.17...GaA
1 crystal layer.

Claims (2)

[Claims] (1) Bringing a saturated melt obtained by heating and melting a semiconductor material into contact with the surface between two semiconductor substrates facing each other,
In a crystal growth method in which the saturated melt is cooled and the semiconductor material in the saturated melt is grown in a liquid phase on the surface of a semiconductor substrate, the surface index of one of the two semiconductor substrates facing each other is A crystal growth method characterized by making the surface index of the other semiconductor substrate different from that of the other semiconductor substrate. (2) Bringing a saturated melt obtained by heating and melting a semiconductor material into contact with the surface between two semiconductor substrates facing each other,
In a crystal growth method in which the saturated melt is cooled and the semiconductor material in the saturated melt is liquid-phase grown on the surface of a semiconductor substrate, the surface area of one of the two semiconductor substrates facing each other is , a crystal growth method characterized in that the surface area of the other semiconductor substrate is larger than that of the other semiconductor substrate.