JPS6377111A - Light-irradiated vapor growth apparatus - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a light irradiation vapor phase growth apparatus for compound semiconductors using an organometallic compound as one of the raw materials.

BACKGROUND OF THE INVENTION Recently, when manufacturing semiconductor devices, coatings have been formed using light irradiation vapor phase growth using laser light or ultraviolet light energy. FIG. 3 is a block diagram of a conventional light irradiation vapor phase growth apparatus for compound semiconductors.

In the figure, 1 is a reaction chamber, 2 is a substrate crystal, 3 is a substrate heater, 4 is a gas inlet, 6 is a gas exhaust port, 6 is a light transmission window, and 7 is a laser beam.

The reaction gas enters the reaction chamber 1 through the gas inlet 4 and reaches the vicinity of the substrate crystal 2'. Here, the reactive gas is excited and decomposed by laser light 7 irradiated through a light transmission window 6 made of a material that transmits laser light, and a film is formed. Although the laser beam 7 can only promote the decomposition of the reactive gas, here the apparatus is configured to selectively heat the substrate crystal 2 or selectively decompose the reactive gas. The substrate heater 3 is an auxiliary heating means.

Problems to be Solved by the Invention In such a conventional apparatus, the reaction products generated by the reaction during film formation are not only exposed to the inner wall of the reaction chamber 1 but also
It adheres to the light transmission window and reduces the transmittance of laser light. Therefore, there is a problem that the reaction rate becomes slow and the reproducibility of the film thickness for each growth is impaired.

The present invention was developed in view of the above-mentioned problems, and it uses a light irradiation vapor phase that prevents reaction products from adhering to the light-transmitting window during each growth and improves the reproducibility of film thickness and the working efficiency of the device. The purpose is to provide a growth device.

Means for Solving the Problems In order to solve the above problems, the present invention is characterized by comprising means for introducing an inert gas such as hydrogen or nitrogen into the inner surface of the light transmission window in parallel to the light beam. It is something.

Effect The effect of this technical means is as follows. That is,
By introducing an inert gas parallel to the light beam from the inner surface of the light-transmitting window during film formation, it is possible to prevent reaction products generated near the substrate crystal from adhering to the light-transmitting window, thereby reducing the light transmittance for each growth. can be kept constant. Furthermore, there is no need to expose the reaction chamber to the atmosphere and clean the light transmission window after every growth. As a result of the above, the reproducibility of the film thickness and crystallinity for each growth and the operating efficiency of the apparatus are dramatically improved.

Embodiments Hereinafter, embodiments of the present invention will be described based on the drawings. 1st
The figure is a block diagram of a compound semiconductor light irradiation vapor phase growth apparatus showing the structure of an embodiment of the present invention, and the same parts as in FIG. 3 are given the same numbers.

Taking GaAs film formation as an example, from the gas inlet 4
Transport material for group elements, triethyl gallium (T.E.G.
): Transport material for 100 C, C7mm and group ■ elements,
7/l/ Schiff (AsH3): es o cc/
In1yt is introduced into the reaction chamber 1. In the reaction tube 1, a substrate crystal 2 (a GaAs substrate is used here) is placed which is auxiliary heated to 400° C. by a substrate heater 3. The upper part of the substrate crystal 2 is irradiated with a laser beam 7 through a light transmission window θ. The wavelength of the laser light preferably matches the absorption peak of the transport material, and here a KrF excimer laser is used. The transported material that has reached the vicinity of the substrate crystal 2 is excited and decomposed by the laser beam 7, and a film is formed on the substrate crystal 2. At this time, G a A that did not normally contribute to film formation
Reaction products such as polycrystals of s and arsenic (As) are exhausted from the gas exhaust port 5, but some of them adhere to the inner wall of the reaction chamber 1 and the light transmission window. However, in the configuration of the present invention, a gas flow guide tube 9 is provided between the light transmitting window 6 and the reaction tube 1, and hydrogen gas is introduced from the inert gas inlet 8.
Since hydrogen gas flows from the inner surface in parallel to the laser beam 7, adhesion of reaction products to the light transmission window 6 can be significantly reduced. It is desirable that the flow rate of this hydrogen gas is at a level that does not overflow the flow of the reaction gas.

Here, hydrogen gas was used as the inert gas, but nitrogen gas or argon gas may also be used. Furthermore, as shown in Figure 2, the direction of incidence of the laser beam may be the same as the direction of introduction of the reaction gas, so that the reaction gas is excited and decomposed before reaching the substrate crystal. There is no leakage of gas flow.

Effects of the Invention As is clear from the above explanation, according to the light irradiation vapor phase growth apparatus for compound semiconductors of the present invention, by providing a means for introducing an inert gas from the inner surface of the light transmission window in parallel to the light beam, Since it is possible to prevent reaction products that impede light transmission from adhering to the light-transmitting window during film formation, the reproducibility of film thickness and the working efficiency of the apparatus are dramatically improved, making this method extremely useful in practice.

[Brief explanation of the drawing]

1 and 2 are schematic configuration diagrams showing one embodiment of the optical vapor phase growth apparatus of the present invention, and FIG. 3 is a schematic configuration diagram showing a conventional optical vapor phase growth apparatus. 1...Reaction chamber, 2...Substrate crystal, 3.
...Substrate heating heater, 4...Gas inlet, 6...Gas exhaust port, 6...Light transmission window, End...Laser Light, 8... Inert gas inlet, 9... Guide tube.

Claims (1)

[Claims] It houses a substrate and has a raw material gas introduction section for forming a vapor-grown film on the substrate, a gas exhaust section for exhausting a reaction gas, and a transmission window for a light beam that induces a chemical reaction. . A light irradiation vapor phase growth apparatus comprising means for introducing an inert gas from the inner surface of the transmission window in parallel to the light beam.