JPS6242514A - Molecular beam crystal growth device - Google Patents

Abstract

PURPOSE:To prevent attenuation of light preventing a view port from becoming cloudy, by providing the device with a construction where light coming from the view point is applied to a substrate through a small hole in a shielding plate which is placed at the focal point. CONSTITUTION:A shielding plate 15 is, for example, made of tantalum and provided with a hole 15a with a diameter of 1mm, and a hole 15a is positioned on the focal point of a lens 12. The plate 15 is arranged a little bit distant from the wall of a chamber 19, and the flow of molecules produced by reevaporation of a substrate 16 is prevented from entering the furnace while the inside of the port 14 is held about the same vacuum degree as that of the chamber. The light is stopped down through the hole 15a and applied to the substrate 16, however, the molecules produced by the reevaporation of the substrate 16 scarcely reach the view port 13 since the hole is small, with the result that the view port 13 does not become cloudy, thereby preventing the the light form being attenuated.

Description

[Detailed Description of the Invention] [Summary] A small hole in a shielding plate that has an optical system that focuses between a view port (light transmission window) and a substrate, and the light that enters from the view port is placed at the focal position. This is a molecular beam crystal growth apparatus configured to irradiate the substrate through the rays.

[Industrial application field]

The present invention is based on molecular beam epitaxy (MBE) using light.
It relates to crystal growth, and more specifically, it relates to a molecular beam crystal growth apparatus configured to suppress clouding of the view boat and prevent attenuation of light.

[Conventional technology]

Recently, research has become active on the MBE method, in which a substrate is irradiated with light (for example, ultraviolet light) to promote crystal growth and impurity diffusion (doping) through a photochemical reaction. Figure 3 shows a gas source MBI that uses light! The device is schematically shown in cross-sectional view, and a substrate 32 heated by a heater 33 is arranged in a chamber 31 maintained in a high vacuum, a port 34 is connected to the chamber 31, and a gas is introduced into the port. tube 35.3
Growth gas and H2 gas are respectively supplied through 6,
A view boat 37 is provided on the opposite side of the substrate, and light emitted from a light source passes through a lens 39 and the view boat 38 and is irradiated onto the substrate 32. The growth gas absorbs light,
For example, crystals are deposited on a substrate by photolysis.

[Problem that the invention seeks to solve]

In order to let light into the device as described above, a view boat is required that can maintain a high vacuum while allowing the light to pass through. For example, when a GaAs crystal is grown on a GaAs substrate, a gas containing As Since a large amount of (eg, arsine) was supplied, As was re-evaporated from the substrate during growth, and this As was deposited inside the viewboat, clouding the viewboat and weakening the light hitting the substrate. In order to prevent this, it was proposed to install a shutter near the view boat, but since the shutter must be kept open during crystal growth, installing a shutter is not very effective in suppressing the dust on the view boat. There is no.

The present invention was created in view of these points, and the MB
An object of the present invention is to provide a device that can prevent fogging of a view boat in a II+ device.

[Means for solving problems]

FIG. 1 is a sectional view of an embodiment of the present invention.

In FIG. 1, the light 11 that passes through the lens 12 and the view boat 13 and enters the boat 14 is irradiated onto the substrate 16 through the hole 15a of the shielding plate 15 arranged at the focal position of the lens L2. There is.

[Effect]

The purpose of the present invention is to not block the light hitting the substrate, block re-evaporation from the substrate, and prevent the view boat from becoming foggy. is small, so most of the molecules re-evaporated from the substrate do not hit the view boat.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

One embodiment of the present invention is shown in the cross-sectional view of FIG. 1, in which 11 is light emitted from a light source (not shown), such as a deuterium lamp, 12 is a lens, 3 is a vinyl boat (light-transmitting window), 14 is a boat, 15 is a shielding plate, 15a is a shielding plate 15
16 is a substrate, 17 is a stage on which the substrate is placed, 18 is a small hole formed in the substrate 16,
A heater for heating to 0° C. and a vacuum chamber 19 are provided. For example, the vacuum chamber is initially maintained at a high vacuum of about 1.times.10" Torr, and then maintained at a vacuum of about I.times.10@-6 Torr when the growth gas is introduced.

Although the gas introduction pipe that supplies growth gas etc. is not shown,
It is connected to another boat connected to chamber 19.

The shielding plate 15 is made of, for example, a tantalum plate, and a hole 15a having a diameter of about 1 mm is formed so that the hole 15a is located at the focal point of the lens 12. The shielding plate 15 is arranged slightly from the wall of the chamber 19, and while the inside of the boat 14 is maintained at the same degree of vacuum as the inside of the chamber, the molecular flow due to re-evaporation from the substrate 16 enters the furnace. Make sure that there is no The shielding plate 15 is preferably installed in a removable manner so that it is also cleaned when the chamber is cleaned.

With the above-described configuration, the light is focused by the hole 15a and then irradiated onto the substrate 16, but the molecules due to re-evaporation of the substrate 16 are small as the hole 15a is as described above.
However, in the illustrated embodiment, when there was no shielding plate, the view boat was clouded at the stage of eviaxial growth on several substrates.
Even when crystal growth was performed on 0 substrates, almost no clouding was observed.

FIG. 2 is a sectional view of another embodiment of the present invention, in which a shielding block 25 is used in place of the shielding plate 15. The block 25 has a tapered aperture 25a formed in its center, and is configured to provide a small hole on the side of the aperture 25a closer to the view boat, so that this small hole is located at the focal point of the lens 12. .

The shape of the block may be either a rectangular parallelepiped or a cylinder, but when it is fixed in the chamber, a small gap is left between it and the wall of the chamber, as in the case of the shielding plate 15. In this embodiment, the aperture 25a is less likely to be clogged and can be used for a longer period of time than a shielding plate.

〔Effect of the invention〕

As described above, according to the present invention, fogging of the view port is suppressed in an MBE apparatus, and is effective in improving workability in a semiconductor device manufacturing process.

[Brief explanation of drawings]

FIGS. 1 and 2 are cross-sectional views of an embodiment of the present invention, and FIG. 3 is a cross-sectional view of a conventional example. 1 and 2, 11 is a light, 12 is a lens, 13 is a view boat, 14 is a boat, 15 is a shielding plate, 15a is a hole, 16 is a substrate, 17 is a stage, 18 is a heater, and 19 is a chamber , 25 is a shielding block, and 25a is an opening.

Claims (1)

[Claims] A light transmitting window (13) is provided on the side opposite to the substrate (16) in the chamber of the furnace connected to the chamber (19), and a light (11) is provided outside the window (13). ) to narrow down the lens (1
2), and a hole (
15a) is arranged, and the position of the hole (15a) is made to match the focal position of the lens (12), and the light (11) is passed through the lens (12), the window (13), and the hole. (15a
) A molecular beam crystal growth apparatus characterized in that it is configured to irradiate a substrate (16) through a substrate (16).