JPS6281020A - Photo-cvd device - Google Patents

Abstract

PURPOSE:To prevent a reaction product from being adhered to a light source or a transparent cylinder by enclosing the light source of a photo-CVD device with a cylinder in a double structure, and supplying unreacting gas to between intermediate chambers, and feeding out the gas from the through-holes of the outside cylinder. CONSTITUTION:A substrate 3 is set on a support 2 which contains a heater in a reaction tank 1, and a light source lamp 5 is disposed oppositely to the substrate. Raw gas is fed through a gas supply port 6 into the tank 1, consumed to form a film, and then fed out of the tank through an exhaust port 7. The lamp 5 is composed of double quartz glass, many holes 11 are opened in an outside glass tube 10, and a unreacting gas supply port 12 is attached to the gap portion. When forming a film by an optical CVC, unreacting gas is supplied from the port 12, and fed through the holes 11 into the tank. Thus, it can prevent the raw gas in the tank from arriving at the surface of the light source lamp.

Description

[Detailed description of the invention] [Technical field to which the invention pertains]

The present invention relates to a photo-CVD apparatus that decomposes a source gas by photolysis and deposits the generated active species on a substrate to form a thin film.

[Prior art and its problems]

A schematic diagram of a device conventionally used as this type of optical CVD device is shown in FIG. 2, with a mercury lamp 5 as an ultraviolet light source.
is placed in the light source chamber 8 adjacent to the reaction tank 1, and the ultraviolet light is irradiated onto the raw material gas through the transparent window 4 attached to a part of the wall of the reaction chamber 1, which is exhausted from the exhaust lower, and the material gas is photolyzed. In the case of amorphous silicon film formation in which a film is formed on the surface of a substrate 3 on a support 2 having a heater by
SiH, 5izH4, or hydrogen as a raw material gas. A gas diluted with a rare gas or the like is introduced from the gas supply port 6. However, in such an optical CVDJ system, a film is constantly formed on the substrate 3, and at the same time, a film is also formed on the window, and after a while after the start of irradiation, the amount of light passing through the window decreases, and finally In order to reduce the adhesion of films to these windows, which have the disadvantage of not forming a film, there are methods such as applying oil for diffusion pumps to the inner surface of the windows, or attaching sheet-like films to the window surfaces, and applying various methods. A method has been devised in which a new film surface is fed out onto the window while it is being wound up. However, even with this, if film formation is continued for a long time, the window will gradually become cloudy, and this problem has not been solved.

[Purpose of the invention] SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide a photo-CVD apparatus that does not reduce the film-forming speed or interrupt film-forming due to a decrease in the amount of light due to clouding of the light entrance window. [Key points of the invention]

In the photo-CVD apparatus according to the present invention, a light source is placed in a reaction tank, the light source is housed in a transparent cylindrical body with a large number of through holes, and the space between the cylindrical body and the light source is filled with non-reactive gas. By being connected to the supply port, a non-reactive gas such as hydrogen or rare gas flows out through the through hole of the cylindrical body, and the raw material gas reaches the light source or the surface of the cylindrical body to form a film. to achieve the above objectives.

[Embodiments of the invention]

FIGS. 1(a) and 1(g)) show an embodiment of the present invention, and parts common to those in FIG. 2 are given the same reference numerals. Reaction P! A substrate 3 is placed on a support 2 containing a built-in heater in a J, and a light source lamp 5 is placed facing the substrate. The raw material gas is fed into the reaction tank 1 through the gas supply port 6, and after being consumed for film formation, the exhaust gas is discharged to the outside of the reaction tank through the exhaust lower. The light emitting surface of the light source lamp 5 is made of double quartz glass, with a gap between the two. A large number of holes 11 are made in the outer glass tube 10, and a non-reactive gas supply port 12 is installed in the gap. When forming a film by photo-CVD, a non-reactive gas such as hydrogen or rare gas is supplied through the gas supply port 12 and sent into the reaction tank through the hole 11. This prevents the raw material gas in the reaction tank from reaching the light source lamp surface.
No film deposition occurs on the lamp surface and the problem of fogging of the light entrance window is solved. The holes 11 are made to have a diameter lfl, and are opened in the glass tube 1o at 11 intervals, and placed in a reaction tank with a pressure of I Torr. When L amount of hydrogen gas was flowed out at a flow rate of 16 m/sec, no clouding occurred on the surfaces of the glass tube 1o and the light source 5. The flow of non-reactive gas with this configuration not only prevents the window from fogging up, but also has the effect of cooling the light source lamp 5 and stabilizing the intensity of the light from the light source. In particular, when a low-pressure mercury lamp is used as a light source lamp, such an effect is important because mercury vapor pressure, which depends on temperature, is an important parameter. Although five light source lamps 5 are used in the above embodiment,
This number is determined depending on the area of film formation on the substrate. Furthermore, in the above embodiment, each lamp has a double tube structure, but each lamp is housed in a common light source chamber in the reaction tank, and non-reactive gas is introduced in a distributed manner into this light source chamber from multiple gas supply ports. However, the light may flow out from a large number of through holes provided in the transparent window on the substrate side of the light source chamber.

【Effect of the invention】

According to the present invention, the light source of the photoCVD apparatus is surrounded by a cylindrical body to form a double structure, and a non-reactive gas is supplied between the intermediate chambers and is caused to flow out from the through hole of the outer transparent cylindrical body. This prevents reaction products from adhering to the light source or the transparent cylindrical body, thereby solving the problem of reduction in light intensity due to cloudiness. Furthermore, since the light source can be cooled by the non-reactive gas, there is also the effect of stabilizing the intensity of the light source.

[Brief explanation of drawings]

FIG. 1 shows an embodiment of the present invention, (al is a front sectional view, (bl is a side sectional view, and FIG. 2 is a sectional view of a conventional CVD apparatus. ■ = reaction tank, 2: support , 3: board, 5: light source lamp,
6; Raw material gas supply port, 7: Exhaust port, 1o. Outer glass tube, 11: hole, 12: non-reactive gas supply port. -7,4 Seven,

Claims (1)

[Claims] 1) A light source was placed in a reaction tank, the light source was housed in a transparent cylindrical body with a large number of through holes, and the space between the cylindrical body and the light source was connected to a non-reactive gas supply port. An optical CVD device characterized by the following.