JPH0122814B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a photochemical reaction device, and more particularly to a photochemical reaction device that prevents a reaction product from adhering to the inside of a transparent window for irradiating reaction light.

[Prior Art] In a conventional photochemical reaction device that performs a photochemical reaction in a gas phase, a window made of, for example, quartz glass is installed on the reaction light source side of a reaction vessel to transmit reaction light. The reaction light is allowed to enter the reaction vessel through this window.

However, in such a photochemical reaction device, reaction products adhere to the inside of the light-transmitting window, that is, on the reaction vessel side, and the amount of incident reaction light attenuates over time, so the reaction operation must be stopped at regular intervals. It was necessary to remove the reactants adhering to the window by removing the reactants, making it impossible to continue the photochemical reaction for a long time.

Therefore, in order to deal with this, (1) Apply fluorine-based oil to the inner surface of the window on the reaction vessel side.

(2) Release non-reactive gas into the light guide.

Such measures have been devised.

However, if fluorine-based oil is applied to the window surface, there is a risk that the product will not only be contaminated by impurities adsorbed to the fluorine-based oil, but also that a film of product will be formed on the surface of the oil and permeate. This causes a decrease in the amount of light.

In addition, simply releasing non-reactive gas into the light guide as in (2) above requires a large amount of non-reactive gas, and the raw material gas is significantly diluted by the non-reactive gas, resulting in product formation. Furthermore, if such dilution is attempted to be suppressed, the reaction gas will diffuse back toward the window, causing the window fogging described above.

That is, as mentioned above, in any case, it is inappropriate and impractical to continue a photochemical reaction for a long time, and in particular, in thin film production techniques that utilize photochemical reactions, there is little damage to the produced film.
Although it is expected to produce a high-quality film, there are difficulties in its adoption, and the problem of fogging on windows has not been solved to this day.

[Objective] In view of the above-mentioned problems, an object of the present invention is to provide a photochemical reaction device that prevents raw material reaction gas and reaction products from directly adhering to the surface of a reaction irradiation light-transmitting window. Our goal is to provide the following.

[Structure] In order to achieve the above object, in the present invention, light from a reaction irradiation light source is supplied to the reaction vessel through a light-transmitting window and a light guide path, and the chemical reaction of the raw material gas in the reaction vessel is caused by the action of the light. In a photochemical reaction device designed to perform the following steps, a gap is arranged along the light-transmitting window around the light guide in contact with the light-transmitting window, and a non-chemically reactive diluent gas is guided from the gap to the light guide. It is characterized by:

[Example] The present invention will be described below in detail and specifically based on the drawings.

FIG. 1 shows an embodiment of the invention.

Here, 1 is the reaction vessel, 2 is the reaction vessel 1
An introduction valve for gas supply is provided on an introduction pipe for introducing raw material gas into the space 1A, and 3 is a blow-off nozzle provided at the tip of the introduction pipe. The reaction vessel 1 is configured in advance so that its space 1A is kept in a vacuum by a vacuum pump 4, and the raw material gas to be reacted is ejected from the blow-off nozzle 3 into the vacuum kept space 1A, and the reaction is carried out inside the vessel 1. Allows photochemical reactions to proceed.

5 is a straight tube attached to the container 1 and has a light guide path 6 in its center, and a cylindrical partition wall 7 is arranged between the inner wall of the straight tube 5 and the light guide path 6 to connect the partition wall 7 and the straight tube. A gap passage 8 is formed between the inner wall of the groove and the inner wall of the groove 5. Further, reference numeral 9 denotes a light-transmitting window for irradiating reaction light, which is attached to the flange portion 5A provided at the end of the straight pipe 5 via an O-ring 10, and the light-transmitting window 9 is formed of, for example, a synthetic quartz plate. ing.

Here, however, an extremely narrow gap 11 is maintained between the end of the partition wall 7 on the transparent window 9 side and the inner surface of the transparent window 9, and furthermore, the partition wall 7
An O-ring 12 is provided around the gap passage 8 formed between the straight pipe 5 and the O-ring 1.
2, the diluent gas is supplied from the diluent gas introduction pipe 13 to the gap passage 8 near the transparent window 9.
14 is a gas adjustment valve for adjusting the amount of dilution gas supplied from the gas introduction pipe 13; 15 is a reaction vessel 1;
An exhaust valve 17 is installed in an exhaust pipe 16 to create a vacuum, and 17 is a light source that transmits reaction light.

It is preferable that the interval between the gaps 11 can be adjusted by slight movement of the partition wall 7 in the direction along the straight pipe 5, and furthermore, the light guide path 6 is connected from the gas introduction pipe 13 through the gap passage 8 and the gap 11. be led to. The flow rate of the diluent gas (eg, a gas that is non-reactive to light and maintained at a higher pressure than the source gas, such as argon or helium) can be adjusted by a gas regulating valve 14.

On the other hand, the cross-sectional shape of the light guide path 6 should be made to match the cross section of the light beam if possible, and even if it is expanded beyond that, it should be kept to the minimum necessary to prevent the dilution gas from dissipating unnecessarily, and to prevent the reaction gas from passing through the light guide path. The gas flow rate is adjusted by the gas adjustment valve 14 so as to prevent the gas from diffusing to the transparent window 9 side through the gas valve 6 .

In the photochemical reaction device configured as described above, light from the light source 17 is projected onto the raw material gas blown out from the nozzle 3 into the space 1A of the container 1 through the transparent window 9 and the light guide path 6, and a photochemical reaction is caused. For example, an amorphous silicon film or the like can be formed on a wafer placed in the space 1A.
At this time, the diluent gas guided through the gap passage 8 is guided toward the light guide path 6 along the gap 11 on the inner surface of the light-transmitting window 9, thereby forming a gas film flow. Since the diluent gas is also filled in the space 1A, it is possible to suppress the reaction gas from being guided to the light-transmitting window 9 from the side of the space 1A, and to prevent reaction products from adhering to the light-transmitting window 9.

The applicant conducted experiments on the photochemical reaction device constructed in this manner under the following conditions, and was able to confirm its effects.

In this experiment, a mixed gas consisting of 2% disilane Si ₂ H ₆ and 98% helium was used as a raw material gas for the reaction. Argon was used as a diluent gas to prevent reaction products from adhering. In addition, in this case, the reaction irradiation light source 1
In Example 7, an Ar.F excimer laser was used, the irradiation intensity was 120 mJ/cm ² (193 nm), and the cross section of the laser beam was approximately 25×3 mm ² .

On the other hand, for the device itself, the cross-sectional area of the light guide path 6 is set to 30
×8 mm ² , the length is 80 mm, the outer diameter of the cylindrical partition wall 7 is 46 mm, and the distance between the pipe 5 as the gap passage 8 and the partition wall 7 is maintained at 1 mm, and the gap 11
The distance between the window 9 and the partition wall 7 was 400 μm.

Under the condition that the pressure in the reaction vessel space 1A of such an apparatus is maintained at 2 to 100 Torr, the flow rate of the above-mentioned reaction gas is supplied while being varied within the range of 50 to 300 cm ³ /min under standard conditions, while As a result of supplying argon as a diluent gas at a flow rate varying within the range of 50 to 100 cm ³ /min, within the range of such flow rate conditions, the inside of the light-transmitting window 9 was not affected by light irradiation for 30 minutes or more. It was possible to form an amorphous silicon film without any adhesion of reaction products and without any cloudiness.

On the other hand, if the antifogging device according to the present invention is not installed, that is, the straight pipe 5 as described above is provided with the partition wall 7.
Argon gas is directly supplied at a flow rate of 500 cm ³ /min without providing a passage 8 or a gap 11, while,
When the above reaction gas was supplied at a flow rate of 100 cm ³ /min to the space 1A kept at 2 Torr and the same laser irradiation was performed, the transparent window 9 fogged significantly, and after only 1 minute and 30 seconds, the reaction gas disappeared. The transmittance at 193 nm drastically decreased from 90% to less than 5%, making it impossible to continue the photochemical reaction.

[Effects] As described above in detail, according to the present invention, the light for photochemical reaction is guided from the reaction irradiation light transmission window to the photochemical reaction vessel along the part of the light guide path in contact with the light transmission window. By forming a gap that guides the flow of non-reactive diluent gas from the surrounding area and filling the light guide path with the diluent gas through this gap, the reaction gas comes into contact with the inner surface of the transparent window and the reaction products are generated. This prevents the adhesion of reaction products to the inner surface of the translucent window over time, unlike conventional methods, which eliminates the need to remove the window at regular intervals to remove reaction products that adhere to the inner surface of the translucent window over a long period of time. It becomes possible to continue the reaction work, and an efficient photochemical reaction device can be obtained.

[Brief explanation of drawings]

FIG. 1 is a block diagram schematically showing an example of the photochemical reaction device of the present invention. 1...Reaction container, 1A...Space, 2...Introduction valve, 3...Blowout nozzle, 4...Vacuum pump, 5
... Straight pipe, 5A ... Flange part, 6 ... Light guide path,
7... Bulkhead, 8... Gap passage, 9... Translucent window,
10... O-ring, 11... Gap, 12...
O-ring, 13...Introduction pipe, 14...Gas adjustment valve, 15...Exhaust valve, 16...Exhaust pipe, 17...
light source.

Claims (1)

[Scope of Claims] 1. A photochemistry system in which light from a reaction irradiation light source is supplied to a reaction vessel through a transparent window and a light guide path, and a chemical reaction of raw material gas in the reaction vessel is carried out by the action of the light. In the reaction apparatus, a gap is provided along the light-transmitting window around the light-transmitting window in contact with the light-transmitting window, and a non-chemically reactive diluent gas is guided from the gap to the light-guiding path. A photochemical reaction device featuring: 2. In the photochemical reaction device according to claim 1, the cross-sectional area and length of the light guide are as follows:
A photochemical reaction device characterized in that it has a minimum size that can prevent the source gas from diffusing into the light-transmitting window and does not cause any problem in guiding the light to the reaction vessel.