JPH01230223A - Manufacture of superlattice - Google Patents

Abstract

PURPOSE:To make a transition layer yielded at a heterointerface thinner than a superlattice layer, by setting a growing temperatures for various semiconductors as specified in a method wherein a plurality of the kinds of semiconductor layers of superlattices on a substrate are formed by vapor growth of organic metal. CONSTITUTION:Growing temperatures of a plurality of the different kinds of semiconductors are set at the temperatures within reaction-rate determining processes. Then, the growing temperatures can be decreased. The growing speed becomes very low. Therefore, a transition layer which is yielded at a heterointerface in continuous growing of the different compound semiconductor becomes thinner than each superlattice layer. The very thin layer is steeply grown with good controllability of the film thickness, and the device having the desired characteristics can be obtained.

Description

[Detailed Description of the Invention] [Summary] It relates to a method for manufacturing a superlattice layer, particularly in the order of several atoms to create a HEMT or a quantum well laser using the M [1CVD (organic metal vapor phase epitaxy) method. The purpose of the present invention is to provide a method for producing a superlattice that makes the heterointerface of semiconductor layers steep when growing crystals of multiple, especially different types of compound semiconductors, and to provide a method for producing a superlattice that makes the heterointerface of semiconductor layers steep. In a method of manufacturing a superlattice consisting of a plurality of compound semiconductor layers on a substrate using a vapor phase growth method using Setting is configuration.

[Industrial application field]

The present invention relates to a method for manufacturing a superlattice layer, and particularly to a method for manufacturing a superlattice layer, and in particular,
HE using the vD (organometallic vapor phase growth) method
The present invention relates to a method for forming a superlattice layer of several atoms order in order to create an MT or quantum well laser.

[Conventional technology and issues to be solved]

Conventional HE! , IT (high electron mobility transistors) and quantum well lasers, for example, extremely thin films or superlattice layers of compound semiconductors on the order of several atoms are formed.

Formation of such a superlattice layer is performed by the MOCVD method described above.

For example, there is an A layer made of GaAs on a GaAs substrate, and on top of that is a Bi2 layer made of A I GaAs.
If the gas switching is steep as shown in FIG. 5A, the hetero interface between the A layer and the B layer becomes clear (steep) as shown in FIG. 5B. However, normally, switching from supply gas A to gas B is difficult, so A
, B cannot be mixed to form a single layer film or a superlattice layer with a steep heterointerface as shown in FIGS. 6A and 6B, and therefore desired device characteristics cannot be obtained.

An object of the present invention is to provide a method for manufacturing a superlattice in which a heterointerface between semiconductor layers is made steep during the growth of crystals of a plurality of compound semiconductors, particularly different types of compound semiconductors.

[Means for Solving the Problems] According to the present invention, the above problems are achieved by forming a superstructure consisting of a plurality of compound semiconductor layers on a substrate using a vapor phase growth method (!, 10CVD method) using thermal decomposition of an organic metal. The problem is solved by a superlattice manufacturing method characterized in that the growth temperature of each of the plurality of compound semiconductors is set to a temperature within each reaction rate-limiting process.

[For production]

According to the present invention, when the MOCVD method in which the growth rate changes depending on temperature in a reaction rate-limiting process is used as a growth method, the growth rate can be extremely slowed by lowering the growth temperature. Therefore, in the continuous growth of multiple, especially different types of compound semiconductors, the number of transition layers that occur at the hetero interface is extremely large compared to the thickness of each superlattice layer, so the superlattice layer interface of each compound semiconductor is formed steeply. Ru.

〔Example〕

First, the principle of the present invention will be explained based on the drawings.

FIG. 1 and FIG. 2 are diagrams showing the relationship between time and gas supply amount, and schematic diagrams showing a superlattice layer formed under the conditions, respectively, for detailed explanation of the present invention.

As shown in FIG. 1, in the present invention, the growth rate is extremely slow, so even when forming an A layer of the order of several atoms,
The growth time TA of the A layer is sufficiently long compared to the mixing time ΔTAR of the gases A and B. Therefore, the transition layer ΔdAB between A and 8 shown in FIG. 2 can be ignored, and the A layer with a steep hetero interface,
Thus, layer B can be obtained.

Figure 3 shows the reciprocal of the growth temperature (1/1' Xl03 to the growth rate) and the growth rate (person/min) when the supply amount of the raw material gas (arsine AsH, trimethylgallium TMG) is kept constant. ) is a diagram showing the relationship between

Generally, in the MOCVD method, if the reaction process is a rate-limiting process, the growth rate changes depending on the temperature.

As shown in Figure 3, in general, when the temperature is below about 600°C, it enters the reaction rate-limiting region, so by lowering the growth temperature, the growth rate can be reduced exponentially. If the temperature is about 350° C. or lower, the growth rate is several layers per minute, that is, one atomic layer is formed in about one minute. This value is almost impossible to achieve with the normal MOCVD method that utilizes a diffusion controlled process.

Ga grown at low temperature using the reaction rate-limiting process in this way
Since the crystals of thin films such as As and AβGaAs are generally in a polycrystalline or amorphous state, a heat treatment is performed after the growth process to convert them into single crystals.

FIG. 4 is a diagram showing a growth temperature program.

According to FIG. 4, the growth temperature is about 350° C., and the annealing temperature and time are about 750° C. and about 10 minutes.

It is thought that the higher the annealing temperature is, the better in order to make the extremely thin film into a single crystal, but if it is too high, thermal damage may occur or the interface will sag due to solid phase sales, so a temperature of 750° C. or lower is appropriate.

〔Effect of the invention〕

As explained above, according to the present invention, an extremely thin film can be grown steeply and with good film thickness control as the growth rate is extremely reduced by low-temperature growth using a reaction rate-determining process. Therefore, it is possible to bring out the device characteristics according to theory.

[Brief explanation of the drawing]

1 and 2 are diagrams showing the relationship between time and gas supply amount, and a schematic diagram showing a superlattice layer formed under the conditions, respectively, for detailed explanation of the present invention, and FIG. , is a diagram showing the relationship between the reciprocal of the growth temperature (1/growth rate 1' FIG. 5A and FIG. 5B are diagrams showing the relationship between time and gas supply amount when the supply gas is abruptly switched, and a schematic diagram showing the ML lattice layer formed under the conditions. FIGS. 6A and 6B are diagrams showing the relationship between time and gas supply amount when the supply gas is not abruptly switched, and diagrams showing the superlattice layer formed under the conditions. 1st rA Figure 2 1/ Growth rate (K-')X10' Figure 3

Claims (1)

[Claims] 1. A method for manufacturing a superlattice consisting of a plurality of different types of semiconductor layers on a substrate using a vapor phase growth method using organic metal thermal decomposition, comprising the steps of: A method for manufacturing a superlattice, characterized in that the growth temperature of each semiconductor is set to a temperature within the rate-limiting process of each reaction.