JPS6386880A - Photochemical reaction utilizing device - Google Patents

Abstract

PURPOSE:To prevent the deterioration of a photochemical reaction due to the clouding of a light entrance window by providing an auxiliary chamber to a reaction chamber in the title photochemical reaction utilizing device through a thin tube, and supplying an inert gas into the auxiliary chamber while projecting laser light on a substrate to be treated in the reaction chamber from the light entrance window of the auxiliary chamber. CONSTITUTION:The inside of the photochemical reaction chamber 2 contg. an Si substrate 1 as the material to be treated is evacuated by a pump 7, gaseous SiH4 and gaseous O2 are simultaneously supplied from cylinders 9 and 10 along with gaseous N2 from a cylinder 8, the laser light 6 from a laser light source 3 is reflected by a mirror, focused by a lens 5, and projected on the surface of the Si substrate 1 to cause a photochemical reaction between SiH4 and O2, and an SiO2 is formed. In this case, the reaction chamber 2 is connected to the auxiliary chamber 16 through the thin tube 15, the laser light 6 is projected from the laser light entrance window 18 provided to the auxiliary chamber 16, and gaseous N2 is supplied under high pressure to the auxiliary chamber 16 from the reaction chamber 2. The reactive gas enters the auxiliary chamber 16, hence the formation of SiO2 on the light entrance window 18 is prevented, the decrease in the input amt. of the laser light due to the clouding of the light entrance window resulting from SiO2 is prevented, and the deterioration of the photochemical reaction is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to a device that uses light to induce a chemical reaction.

[Prior art and its problems] 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 laser light source 3. an optical system consisting of a mirror 4 and a lens 5 for irradiating the semiconductor substrate 1 with a laser beam 6; a vacuum pump 7 for evacuating the reaction chamber; and gas pumps 8 to 9.
It consists of a mass flow meter 11 and a gas system that supplies reactive gas to the reaction chamber 2.

The reactive gas introduced into the reaction chamber 2 from the gas pumps 9 and 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 and decomposes. 5iHn gas and ε supplied from gas pump 9? 5 iOz is produced with the gas and deposited on the surface of the semiconductor substrate l. When this device is used, the temperature of the semiconductor substrate 1 is 100 to 200'
Even if the C content is extremely low, a high quality thin film can be obtained without reducing the growth rate.

However, if the above chemical reaction is not a surface reaction, the laser beam 6
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 chamber at the light entrance window 12 of the reaction chamber 2, and over time they begin to block the laser beam 6, causing the semiconductor substrate l
This will suppress the above reaction. 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-fog 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 pump 8 only onto the light entrance window 12 for one reaction. Methods have been considered to prevent the 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 impossible to suppress the change in film growth rate over time.

[Object of the Invention] An object of the present invention is to provide a photochemical reaction utilizing device that can prevent fogging of a light incident window portion over a long period of time and allow a chemical reaction on a substrate surface to proceed stably.

[Emission 1! Key points 1 of 1] The present invention uses a thin tube to pass incident light into a light entrance window of a reaction chamber. An auxiliary chamber is provided in the auxiliary chamber, an inert gas adjusted to have a more positive pressure than the reaction chamber is introduced into the auxiliary chamber, and the flow of the inert gas is directed from the auxiliary chamber toward the reaction chamber. The reactive gas is completely removed from the entrance window to prevent reaction products from accumulating there.

The inner diameter of the thin tube is preferably about 1.5 to 5 times the diameter of the incident light beam in order to prevent reaction products from being deposited on the inner wall of the IB tube.

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

FIG. 1 shows an embodiment of the present invention in the case of forming a silicon oxide film on a silicon substrate, and the same parts as in FIG. 2 are given the same reference numerals.

The reaction chamber 2 has a vacuum pump 7 and a gas pump 8 to 1.
0. The nine reaction chamber 2 is similar to the conventional one in that it has a gas system consisting of a mass flow meter 11.A thin tube 15 is further connected to the light entrance window 14 of the nine reaction chamber 2, and an auxiliary chamber 16 is provided above the thin tube 15. An inert gas introduction pipe 17 opens into the chamber 16 from the gas system. Further, above the auxiliary chamber 16, a laser light source 3 and a mirror 4 are provided.
, an optical system consisting of lenses 5 is arranged.

The silicon substrate 1 is placed on the bottom plate heated to 200 °C of the reaction chamber 2. An ArF excimer laser is used as the light source 3 to induce the reaction, and the wavelength is 19.
A 3 nm oscillated laser beam 6 is deflected by a mirror 4 and is incident on a lens 5. The laser beam 6 narrowed down by the lens 5 enters the auxiliary chamber 16 through the light entrance window 18 of the auxiliary chamber 16, passes through the thin tube 15, enters the reaction chamber 2 through the light entrance window 14, and is exposed to the silicon substrate 1. focus on the surface.

As the reaction gas, 5iHi gas is supplied at 5 m1/min from the pump 10 with the VT amount controlled by the mass flow meter 11;
800m from Ponbe 9 17 minutes of N20 gas, Ponbe 8
From 65m1/min of N? The inside of the reaction chamber 2 into which the gas is introduced is evacuated by the vacuum pump 7, and lTo r r
Maintained by front and rear pressure. When the above reaction gas is allowed to flow for 10 minutes, a 2000-layer thick silicon film is deposited on the silicon substrate l.

The inside of the auxiliary chamber 16 is filled with N2 gas from the pump 8 via the inert gas introduction pipe 17, and the pressure is positive from the inside of the reaction chamber 2, so this N2 gas is in a small amount. 15 into the reaction chamber 2, SiH from the reaction chamber flows into the reaction chamber 2.
< and N20 gas can be prevented from flowing back into the auxiliary chamber 16, and the light incident path, that is, the light entrance window 18 of the auxiliary chamber, the inner wall of the auxiliary chamber 16, and the thin tube 15.
It is possible to completely prevent silicon oxide from depositing on the inner walls of the

1- In the above-mentioned embodiment, the case where a silicon oxide film is deposited was explained, but the invention is not limited thereto, and for example, CI? It can also be applied to photoetching of polysilicon using gas.

In this case, the laser beam is XeCl excimer laser 3
08nm oscillation light is used, and 10To is used in the reaction chamber.
r CI before and after r? Introduce gas. When an AI mask is placed directly above a silicon substrate on which polysilicon is deposited and the aforementioned laser beam is irradiated, anisotropic etching according to the mask pattern is achieved. In this case as well, N
By introducing C12 gas, the light entrance window can be prevented from being exposed to the C12 gas, and the inner wall of the light entrance window can be prevented from being etched and fogged.

Furthermore, the present invention is not limited to photodeposition and etching.
It goes without saying that this method can be applied to all devices that utilize photochemical reactions, such as doping with light and cleaning.

[Effects of the Invention] According to the invention, light is not directly incident on the reaction chamber from an external optical system, but is passed through an auxiliary chamber. The inert gas adjusted to have a more positive pressure than the reaction chamber was introduced into the auxiliary chamber, and the flow of the inert gas was directed from the auxiliary chamber toward the reaction chamber. The reactive gas introduced into the reaction chamber does not touch the light entrance window of the auxiliary chamber, which prevents the light entrance window from becoming cloudy due to reaction over a long period of time, allowing the Ibichemical reaction to proceed stably on the substrate surface. The number of maintenance required to remove fogging is significantly reduced, and the operation of the equipment is significantly improved.

[Brief explanation of the drawing]

FIG. 1 is a structural layout diagram of an embodiment of the present invention. FIG. 2 is a structural layout diagram of a conventional device. 1st race - silicon substrate, 2nd - Φ reaction chamber,
3 e e-laser light source, 7. [phase] Vacuum pump, 8 to 10... Gas cylinder, 11... Mass flow meter, 14... Light entrance window of fist reaction chamber, 15... Thin tube, 16 . . . Auxiliary chamber, 17. Inert gas introduction pipe, 18. Light entrance window of the auxiliary chamber. Figure 1 is the trousers.

Claims (1)

[Claims] 1) In an apparatus that uses light to induce a chemical reaction, an auxiliary chamber is provided in the light entrance window of the reaction chamber via a thin tube, and an inert gas introduced into the auxiliary chamber is supplied from the auxiliary chamber. A photochemical reaction utilizing device characterized in that the light flows into the reaction chamber through the thin tube, and the light is made to enter the reaction chamber from the light entrance window of the auxiliary chamber through the thin tube. 2) The device according to claim 1, wherein the incident light is a laser beam, and the inner diameter of the thin tube is 1.5 to 5 times the beam diameter of the laser beam. .