JPH0642453B2 - Optical CVD device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a photo-CVD apparatus, and more particularly to a photo-CVD apparatus having an improved window for transmitting irradiation high-energy light.

[Conventional technology]

In recent years, amorphous silicon films have come to be used in various applications. For example, an optical sensor using an amorphous silicon film, a solar cell, or an electrophotographic photoreceptor is widely used as one having good performance. Conventionally, the amorphous silicon film has been formed by the plasma CVD method or the reactive sputtering method. By the way, in these methods, the raw material gas is reacted with the discharge energy to form a film, but it is difficult to accurately control the discharge energy, so it is necessary to form a film having stable performance with good reproducibility. There was a problem that I could not do it.

Therefore, an optical CVD method has been proposed in which the control of reaction energy is relatively easy.

FIG. 2 is a schematic sectional view of an example of what has been conventionally proposed as an optical CVD apparatus for forming a film by the optical CVD method. In FIG. 2, reference numeral 11 is a reaction container, and means 12 for supporting a substrate on which a film is to be provided is provided in the reaction container 11, and the substrate is heated in the vicinity of the supporting means 12. Means 13 are provided. A window 14 for irradiating high energy light from the outside to the inside of the reaction container 11 is formed in the reaction container 11 at a position facing the substrate supporting means 12. A raw material gas introduction pipe 15 and an exhaust pipe 16 are also connected to the reaction vessel 11. A source gas source (not shown) is connected to the source gas introduction pipe 15 via a valve (not shown), while a pressure reduction source (not shown) is connected to the exhaust pipe 16 via a valve (not shown). No) For example, a vacuum pump is connected.

On the other hand, a light source 17 for high energy light is arranged outside the reaction vessel 11, and 18 is a reflecting mirror for guiding the light from the light source 17 to the window 14.

When forming a film, the substrate A such as glass or ceramic is fixedly supported on the substrate supporting means 12, the inside of the reaction vessel 11 is evacuated by a reduced pressure source, and the source gas such as silane (from the source gas introduction pipe 15 into the vessel 11). SiH ₄ ) gas or disilane (Si ₂ H ₆ ) gas is introduced. Then, while heating the substrate supporting means 12 and the substrate A by the heating means 13, a light source 17, for example, an excimer laser (Excimer Laser) is used.
high energy light B is emitted from a light source in the ultraviolet region such as a mercury light source or a xenon lamp, and the light B is emitted through a window 14 (for example, a quartz glass plate which is an ultraviolet light transmissive material). From the base material A into the reaction container 11 by photochemical reaction of the raw materials.
A silicon hydride film, for example, is formed thereon.

The film formation on the substrate A based on the photochemical reaction is represented by the following reaction formula, for example.

[Object of the Invention] In the photo-CVD apparatus as described above, however, the reaction is carried out over the entire area irradiated with the light B in the reaction vessel 11. Although more deposition can be performed on substrate A by heating substrate A, window 14
Deposition is also performed on the inner surface of the. Therefore, after a long period of use, the light transmittance of the window 14 decreases, and there is a problem that the reaction speed, that is, the film forming speed, decreases due to insufficient irradiation energy.

An object of the present invention is to solve the above problems.

[Outline of Invention]

According to the present invention, in order to solve the above-mentioned problems of the prior art, an optical CV characterized in that the window has a light focusing property.
D equipment is provided.

〔Example〕

Hereinafter, specific examples of the photo-CVD apparatus of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic sectional view showing an embodiment of the photo-CVD apparatus according to the present invention. In FIG. 1, 11 is a reaction container, 12 is a substrate supporting means, 13 is a heating means, 15 is a source gas introducing pipe, 16 is an exhaust pipe, 17 is a light source, 18 Are reflecting mirrors, which are almost the same as those in the above-mentioned conventional photo-CVD apparatus. 19
Is a beam expander and is arranged to expand the width of the light from the light source 17. Reference numeral 20 denotes a window having a light converging property, and a spherical convex lens is used in this embodiment.

In the apparatus of this embodiment, the collimated light B having a widened width is made incident on a relatively wide area (for example, a diameter of 1 to 10 cm) of the window 20 and is condensed in the reaction container 11. The base A is located near the focal point. As a result, the light intensity is increased in the vicinity of the substrate A and the photochemical reaction is actively performed, while the light intensity is relatively weak in the vicinity of the window 20, so that the photochemical reaction does not proceed. Thus, only the substrate A is deposited, and the window 20 is substantially not deposited. Such effects are explained by the multiphoton absorption reaction.

Since the irradiation light spot on the substrate A is relatively small in the apparatus of this embodiment, when the film is formed over a large area, the substrate A is two-dimensionally moved in a direction perpendicular to the light irradiation direction by a well-known two-dimensional driving means. Just move it. Further, by appropriately setting the movement route pattern for this two-dimensional movement, it is possible to selectively deposit only on relatively small dots or relatively thin lines.

In the above embodiments, the case where the shape of the window 20 is the shape of a spherical convex lens is illustrated, but the same effect can be obtained by using a so-called Fresnel convex lens in the device of the present invention, and in this case, the thickness of the window 20. Can be thinned.
In the device of the present invention, the window 20 may have the shape of a cylindrical convex lens. In this case, the light is focused linearly, and the movement direction when forming a film over a large area is one direction. Good.

〔The invention's effect〕

According to the photo-CVD apparatus of the present invention as described above, the light transmittance of the window can be maintained good even after long-term use.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic sectional view of an optical CVD apparatus of the present invention. Second
The figure is a schematic sectional view of a conventional photo-CVD apparatus. 11: reaction container, 12: substrate supporting means, 15: source gas introduction pipe, 16: exhaust pipe, 17: light source, 20: window.

Claims (1)

[Claims] 1. Light for irradiating high-energy light from the outside through a window formed in a reaction container to cause photochemical reaction of a source gas in the reaction container and deposit a film on a substrate supported in the reaction container. In the CVD apparatus, the window has a light focusing property, which is an optical CVD apparatus.