JPS63277769A - Device for utilizing photochemical reaction - Google Patents

Abstract

PURPOSE:To prevent cloudiness of a light incident window part and to stably advance chemical reaction on the surface of a substrate by providing a means for heating the light incident window part of a reaction chamber. CONSTITUTION:In a device for utilizing photochemical reaction wherein a silicon oxide film or the like is formed on a silicon substrate 1, electrically-conductive substance 14 is coated in a band-shape on quartz glass constituting the light incident window part 12 of a reaction chamber 2. The light incident window part 12 is heated by allowing current to flow through the electrically-conductive substance 14. Further a heater may be provided around the light incident window part 12. The deposition velocity onto the light incident window part 12 of a reaction product in the reaction chamber 2 is lowered by the rise in temp. of the light incident window part 12 and the cloudiness of the light incident window part 12 is inhibited.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device that uses light to induce a chemical reaction, and particularly to a technique for preventing fogging of a light entrance window thereof.

[Conventional technology]

As this type of photochemical reaction utilization device, a device as shown in FIG. 2 has been known. That is, this device includes a reaction chamber 2 in which a semiconductor substrate 1 is installed, a photochemical system consisting of a laser light source 3, a mirror 4, and a lens 5 for irradiating the semiconductor substrate 1 with laser light 6, and a reaction chamber 2. Vacuum pump 7 for evacuation and gas cylinder 8~
10, and a gas system consisting of a mass probe meter 11 for supplying reactive gas to the reaction chamber 2. The reactive gas introduced into the reaction chamber 2 from the gas cylinder 9.10 absorbs the energy of the laser beam 6 irradiated from the light entrance window 12 at the upper part of the reaction chamber 2, decomposes, and decomposes the reactive gas supplied from the gas cylinder 10, for example. 5iO1 is generated from the 5iHn gas and the 0 gas supplied from the gas cylinder 9, and a silicon oxide film is deposited on the surface of the semiconductor substrate 1. When this device is used, the temperature of the semiconductor substrate 1 is 1
Even at extremely low temperatures of 00 to 200°C, high-quality thin films can be obtained without reducing the growth rate.

However, if the above chemical reaction is not a surface reaction, then
The reaction proceeds in the region through which it passes, and reaction products are deposited. That is, reaction products adhere to the interior of the light entrance window 12 of the reaction chamber 2, and over time they begin to block the laser beam 6, thereby suppressing the reaction on the semiconductor substrate 1. Therefore, preventing reaction products from adhering to the laser beam entrance window is an essential technology for photochemical reaction utilization devices. For this reason, conventionally, an anti-fogging nozzle 13 is opened toward the light entrance window 12 in the reaction chamber 2, and an inert gas such as nitrogen is locally sprayed from the gas cylinder 8 only onto the light entrance window 12, thereby reducing the reactivity. Methods have been considered to prevent gas from flowing into the vicinity of the light entrance window 12. However, with such a simple method, gas turbulence occurs and it is difficult to completely remove the reactive gas from the light entrance window. Therefore, after a long period of laser beam irradiation, the light entrance window begins to become cloudy, and there is a problem in that it is not possible to suppress changes in the film growth rate over time.

[Problem that the invention seeks to solve]

SUMMARY OF THE INVENTION An object of the present invention is to provide a photochemical reaction utilizing device that can prevent fogging of a light entrance window portion for a long period of time and allow a chemical reaction on a substrate surface to proceed stably.

[Means for solving problems]

This object is achieved according to the invention by configuring the light entrance window of the reaction chamber to be heatable.

The heating temperature of the light entrance window is advantageously selected to be between 200 and 500°C.

[Effect]

In the present invention, the temperature of the light entrance window increases by heating the light entrance window, and the deposition rate of reaction products in the reaction chamber on the light entrance window decreases, thereby increasing the temperature of the light entrance window. Clouding is suppressed.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a configuration diagram of an embodiment of the present invention, and the same parts as in FIG. 2 are given the same reference numerals. The configuration in Figure 1 is the second
The difference from the one in the figure is that it does not have the anti-fog nozzle 13,
Instead, the quartz glass constituting the light entrance window 12 is coated with a conductive substance 14 in the form of a band, and by passing an electric current through the conductive substance 14, it is heated and the temperature of the light entrance window 12 is raised. That's what you're supposed to get.

Next, a method of forming a silicon oxide film on a silicon substrate using this apparatus will be described.

The silicon substrate l is placed on the bottom plate heated to 200°C in the reaction chamber 2. An ArF excimer laser is used as the light source 3 to induce the reaction, and the wavelength is 193°C.
The oscillation laser beam 6 of nm wavelength is deflected by a mirror 4 and enters a lens 5. Laser light 6 narrowed down by lens 5
enters the reaction chamber 2 through the light entrance window 12,
Focus on the surface of silicon substrate 1.

The reaction gases include SiH4 gas at 5 d/min from cylinder 10, N, O gas at 8001 d/min from cylinder 9, and N, O gas from cylinder 8 to 6, whose flow rate is controlled by mass flow meter 11.
The inside of the reaction chamber 2 into which N gas is introduced at 5 d/min is evacuated by a vacuum pump 7 and maintained at a pressure around ITorr.

When the above reaction gas is allowed to flow for 10 minutes, a silicon oxide film with a thickness of 2000 nm is deposited on the silicon substrate 1. On the other hand, since the light entrance window 12 is heated and its temperature rises due to the current flowing through the conductive material 14, the deposition rate of the silicon oxide film on the light entrance window 12 is suppressed. rarely accumulates.

Note that the method of heating the light entrance window is not limited to the above-mentioned example, and heating may be performed by disposing a heater around the light entrance window.

Furthermore, although the above-described embodiment describes the case where a silicon oxide film is deposited, the present invention is not limited thereto, for example, C2
It goes without saying that it can be applied to photoetching of polysilicon using 8 gases, and can also be applied not only to photodeposition and etching, but also to all devices that utilize photochemical reactions, such as photodoping and cleaning.

〔Effect of the invention〕

According to the present invention, the rate of adhesion of reaction products to the window is reduced by heating the light incident window of the reaction chamber, which prevents fogging of the window for a long period of time and improves the substrate surface. Since the above chemical reaction can proceed stably and the life of the window is extended, it is possible to improve the operating rate of the equipment.

[Brief explanation of the drawing]

FIG. 1 is a structural layout diagram of an embodiment of the present invention, and FIG. 2 is a structural layout diagram of a conventional device. 1... Silicon substrate, 2... Reaction chamber, 3
...Laser light source, 7...Vacuum pump, 8-
DESCRIPTION OF SYMBOLS 10... Gas cylinder, 12... Light incidence window part of reaction chamber, 14... Electrically conductive material of light incidence window part. Figure 1 Sword pants■

Claims (1)

[Scope of Claims] 1) A photochemical reaction utilization device that uses light to induce a chemical reaction, characterized in that a light entrance window of a reaction chamber is configured to be heatable. 2) A photochemical reaction utilization device according to claim 1, wherein the heating temperature of the light entrance window of the reaction chamber is 200 to 500°C.