JPS62144320A - Manufacture of super-lattice semiconductor - Google Patents

Abstract

PURPOSE:To obtain a super-lattice semiconductor characterized by a large area and steep composition change at an interface with good reproducibility, by turning ON and OFF the projection of optical energy so that the optical energy is not projected in growing a first thin film and the optical energy is projected in growing the second thin film, in two kinds of compound semiconductor thin films constituting a super lattice. CONSTITUTION:A constant temperature bath 120 is filled with trimethylgallium TMG, and a constant temperature bath 121 is filled with trimethylaluminum TMA. A substrate 109 is mounted on a carbon susceptor 110 and undergo induction heating to 500-800 deg.C by a high frequency power source 111. At first, a Ga0.9Al0.1As thin film is grown to 10-100Angstrom by an MOCVD method. Then, under this state, light from an ultraviolet light source 101 is directly projected on the surface of the substrate by opening an optical shutter 133. Thus, decomposition of the TMA is accelerated by the ultraviolet light, and GaAlAs having much Al composition is grown. A super-lattice semiconductor can be manufactured only by turning ON and OFF the optical energy. Therefore, steepness at an interface can be ensured, and an ideal super-lattice semiconductor can be formed.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for manufacturing a superlattice semiconductor.

[Summary of the invention]

The present invention provides a method for manufacturing a superlattice semiconductor in which two types of compound semiconductor thin films with different lngs are alternately and repeatedly stacked. When irradiated, thin films with different compositions are formed, so of the two types of compound semiconductor thin films that make up the superlattice semiconductor, no light energy is irradiated during the growth of one thin film, and no light energy is applied during the growth of the other thin film. By repeatedly turning on and off the irradiation of light energy to produce a superlattice semiconductor, the composition of the superlattice interface changes sharply, making it possible to control the thickness of the ultra-thin film that makes up the superlattice. This makes it easy to manufacture semiconductors with a near-ideal superlattice.

[Conventional technology]

Conventional methods for manufacturing superlattice semiconductors have been carried out by vapor phase growth methods such as molecular beam epitaxy (hereinafter referred to as MBE method) or MOCvD method. In the MBE method, changes in the composition of the superlattice thin film were controlled by opening and closing the shutter of the evaporation source.

MOC again! In pyrolytic chemical vapor deposition methods such as the VD method, superlattice semiconductors have been manufactured by abruptly switching the flow rate ratio of raw material gases.

For example, the case of the MO(1!VD method will be explained using FIG. 1. In the case of the conventional MOCVD method, in order to form a superlattice structure, for example, in the case of a superlattice of GaAtAs and GaAS, the trimethyl Gallium (hereinafter referred to as TMG)
(denoted as ) (123) Mass 70- Con) Pass the solenoid valve (M4) using hydrogen gas whose flow rate is controlled by a roller, and transfer it to the rotary pump (151) L Flow, i Tough Flow 0
- Arsine (ASHs) gas whose flow rate is controlled by the controller (122) is flowed into the reaction tube (10B), and at the start of film formation, the valve (114) is closed and the valve (1j5) is opened to introduce TMG into the reaction tube. GaAθ thin film was introduced into 10~10
Let it grow for 0 years. Thereafter, the trimethylaluminum (121) (hereinafter referred to as TMA) that had been previously flowed through the valve (116) was released into the TMA by opening the valve (117).
(108) to form a GaA4As thin film from 10~
Form 100^. By repeating this series of operations many times, a superlattice structure thin film was manufactured.

[Problems and Objectives to be Solved by the Invention] However, in the prior art described above, first, in the case of the MBE method, it is possible to form an interface with a steep compositional change, but it requires a high vacuum container and is difficult to form. It takes a long time to form a film, making it difficult to mass-produce.
Another problem is that it is difficult to uniformly form a film over a large area.

In addition, in the case of the HocvD method described above, thin films with different composition ratios are formed by switching the gas flow rate, so raw gas components left inside the gas piping or reaction tube when changing the gas flow rate are involved in film formation. The problem is that a sharp change in composition at the interface is not guaranteed, making it difficult to realize a semiconductor with good electro-optical properties with good reproducibility.

Furthermore, the above-described method has the problem of poor reproducibility due to the complicated gas switching operation.

The present invention is intended to solve these problems, and its purpose is to manufacture a superlattice semiconductor that is uniform over a large area, has a steep compositional change at the interface, and can be obtained with good reproducibility. It's about providing a method.

[Means for solving problems]

In the method for manufacturing a superlattice semiconductor of the present invention, of the two types of compound semiconductor thin films constituting the superlattice, the growth of the first thin film is not irradiated with optical energy, and the growth of the second thin film is irradiated with light energy. The method is characterized in that a film is formed by irradiating energy and then repeating the same on and off irradiation of light energy.

[Effect]

According to the above configuration of the present invention, the decomposition of the source gas is promoted by light energy, and the elemental composition ratio in the thin film changes between when light is irradiated and when no light is irradiated.

Therefore, for example, MOC! In the case of the VD method, the flow rate of the raw material gas is kept constant, and the irradiation of light energy can be turned on and off using an optical shutter, so it is easy to create thin films with different composition ratios without changing the gas flow. can be grown, and the light can be turned on and off in an extremely short time, so the steepness of the compositional change at the interface is guaranteed [Example] Figure 1 shows an example of the present invention. It is a main configuration diagram of a superlattice semiconductor manufacturing apparatus in (120), in which a TMG is installed in a constant temperature oven.
However, the constant temperature bath (121) is filled with TMA.

Supply hydrogen gas from the hydrogen gas cylinder at (128),
10B) into the reaction tube. (127) A 8 E
AsH gas is introduced into the reaction tube (10B) from the I3 gas cylinder.

The substrate (109) is placed on the carbon susceptor (110) and heated to 500°C to 80°C by the high frequency power supply (111).
It is induction heated to 0°C. Traditional MOC! G a O, 9Ato, tAs thin film is grown 10 to 100 times using the same growth procedure as the VD method, and in that state, a (101) ultraviolet light source (in the case of this example, ArF excimer is used as the oscillation medium) is used. excimer laser (oscillation wavelength 195 n
By opening the optical shutter of (133), the light of an excimer laser (using light with an oscillation wavelength of 222 nm) using an excimer as an oscillation medium is irradiated directly onto the substrate surface. do. Then, the decomposition of TMA is promoted by ultraviolet light, and growth begins in GaAtAs, which has a high At composition.

FIG. 2 shows the relationship between the A1 composition in GaAtAs and the amount of laser light when irradiated with a 196% m excimer laser. 2223 in Figure 3? The relationship between the A1 composition ratio of GaAAAs and the amount of laser light when irradiated with FL excimer laser is shown. In either case, the At composition is greater during laser beam irradiation. Further, in the case of a laser beam field of 222% m, the absorption coefficient of TMA is larger than that of TMG, so the At composition ratio changes greatly.

FIG. 4 shows that in the apparatus of this embodiment, the gas flow rate is switched to obtain G a O, 9 A to, t A s/G a
This figure compares the steepness of the compositional interfaces of o, 5AAo, and sAs, and the steepness of interfaces of the same composition formed by turning on and off a 2225m laser beam. It can be seen that the steepness of the interface is improved by laser light irradiation.

In this example, GaAs/GaAt was formed by MOOVD method.
Although we have described the case of Ag superlattice, a similar manufacturing method can be used for InG
It goes without saying that this method is effective in realizing other UV group semiconductor superlattices such as aA11l system or InGaP system.

It goes without saying that it is also effective in producing not only m-v group superlattice semiconductors but also ■-■ group and ■- group superlattice semiconductors.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to manufacture a superlattice semiconductor simply by turning on and off light energy, so the steepness of the interface can be guaranteed, and the effect that an ideal superlattice semiconductor can be manufactured is achieved. have As a result, when a semiconductor laser is manufactured using a superlattice semiconductor, it is possible to manufacture a laser with a low threshold, short wavelength oscillation, and high reliability.

Furthermore, since the film thickness is easy to control, the selection of the oscillation wavelength is
This is possible by controlling the film thickness.

Furthermore, it is useful for improving the characteristics of high-speed switching elements that apply two-dimensional electron gas, such as HFiMT.

Furthermore, since the OVD method can be applied to uniformly form a film over a large area, mass productivity and yield can be improved.

[Brief explanation of drawings]

FIG. 1 is a main configuration diagram of a manufacturing apparatus according to the superlattice semiconductor manufacturing method of the present invention. □ Figure 2 shows the concentration of ht atoms in a GaAtAs thin film and 195
Figure 3, which is a relationship diagram with the %m ultraviolet laser light lid, shows the relationship between GaA
Figure 4, which is a relationship diagram between the AA atomic number concentration in the tAs thin film and the 222 am ultraviolet laser light intensity, is a distribution diagram of the AL atomic number concentration at the interface of the GaA7As thin film in the film thickness direction. (101)...Ultraviolet light source (104)...Reflection mirror (107)...Synthetic quartz window (108)...Reaction tube (109)... ...Single crystal substrate (1j1) ...High frequency power supply (112) to (119) ...... Electromagnetic pulp (12
0), (121)...Organometallic compound (122
) to (126)...Mass 70-controller (150 units, (131)...Rotary pump (1,35)...Optical shutter and above Applicant: Seiko Epson Co., Ltd. Agent Patent Attorney Mogami (1 other person) Likelihood and 1-vLE diagram 2nd
Ward number 3 moon! 7! (S) HiyuAρA, thin film kyoumeme Anoh) Number concentration. 11irs Part 4 Figure 4

Claims (5)

[Claims] (1) A method for manufacturing a superlattice semiconductor in which a superlattice semiconductor formed by alternately and repeatedly stacking two types of compound semiconductor thin films with different energy band gaps (hereinafter referred to as Eg) is deposited by pyrolysis chemical vapor deposition. Of the two types of compound semiconductor thin films, the growth of the first thin film was not irradiated with light energy, and the growth of the second thin film was irradiated with light energy; A method for manufacturing a superlattice semiconductor, characterized in that a film is formed by repeatedly turning on and off. (2) The wavelength range of the light energy is in the ultraviolet light region, and is a wavelength that can be absorbed by any of the growth materials of the compound semiconductor thin film. A method for manufacturing superlattice semiconductors. (3) The superlattice semiconductor according to claim 1, wherein the pyrolytic chemical vapor deposition method is a vapor phase growth method (hereinafter referred to as MOCVD method) using an organometallic compound as a raw material. manufacturing method. (4) The method for manufacturing a superlattice semiconductor according to claim 1, wherein the light energy is irradiated directly onto a growth single crystal substrate. (5) The method for manufacturing a superlattice semiconductor according to claim 1, wherein the light source of the optical energy is a laser light source.