JPH05190473A - Photo cvd apparatus - Google Patents

Abstract

PURPOSE:To obtain a photo CVD apparatus capable of mass production industrially, by generating a photochemical reaction for a reactive gas and emitting light with the wave number non-absorbed for a reaction product to the reactive gas. CONSTITUTION:Each formed face of substrates 1 is vertically arranged along the stream of reactive gas which is introduced from the upper part and is discharged to the lower part at certain intervals. The substrates 1 are heated by halogen auxiliary heaters 7 mounted on the upper and lower part of a quartz hood 54 in addition to ceramic heating elements 9. The FIR heating elements 9 for photochemical reaction in which light with the wave number of 1100 to 500cm<-1> is emitted are installed within a reactor as the upper and lower light sources. In the ceramic heating elements 9, a reaction product transmits the FIR even if the reaction product is formed on the ceramic surface of the heating elements 9. Thus, the heating elements 9 are not installed outside the reactor and can be provided inside the reactor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a photogas phase method (Photo Chemical V) using far infrared light having a wave number of 300 to 1500 cm ^-1 , preferably 500 to 1100 cm ^-1 (hereinafter simply referred to as FIR).
aporDeposition (hereinafter referred to as Photo CVD) or photo plasma vapor phase method (Photo Plasma Chemical Vapor Diposi)
The present invention relates to a photo CVD apparatus (photochemical vapor phase reaction apparatus) capable of mass production by means of PPCVD.

[0002]

SUMMARY OF THE INVENTION The present invention strongly emits light having a wave number of 1500 cm ^-1 or less as compared with light having a wave number of 1500 cm ^-1 or more,
The feature is that the light that emits the peak light as the continuous light at the wave number of cm ^-1 or less is used as the light source for Photo CVD including heating.

Therefore, the present invention is characterized in that a ceramic heating element is used for the FIR instead of the laser light, and light is irradiated to a wide space in the reaction furnace.

[0004]

2. Description of the Related Art Conventionally, in a photo-CVD method, a substrate having a surface to be formed is heated from below the substrate, while the surface to be formed, which is the upper surface of the substrate, is vertically upward from the outside of the reactor. A method is known in which irradiation of ultraviolet light causes photoexcitation of the reactive gas on the surface by irradiation of light to cause a photochemical reaction.

This conventional method has a major industrial defect that it cannot form a surface having a size equal to or larger than the area of irradiation light.

Further, for example, when silicon is to be formed using silane, a part of the photoexcited silicon adheres to the window for light irradiation and absorbs the irradiation light, so that it becomes a reactive gas. Had a drawback that the intensity of the irradiation light was significantly weakened.

Further, quartz glass, which is generally used as a window material, has a drawback that it cannot transmit far-infrared light of 200 nm or less and far-infrared light of a wavelength of 3.5 μm or more (wavenumber of 3000 cm ⁻¹ or less). Was there.

For this reason, although the photo-CVD method has the feature that it does not damage the surface of the substrate, it cannot be applied to mass production by the direct excitation method.

[0009]

The present invention eliminates these drawbacks and proposes a photo-CVD apparatus which can be industrially mass-produced for the first time.

[0010]

In the present invention, the reactive gas undergoes photoexcitation or photochemical reaction upon irradiation with light. However, the reaction products are limited to materials or wave numbers that do not or do not absorb the irradiation light.

Therefore, in the present invention, in a semiconductor containing silicon as a main component, infrared light having a light energy smaller than the optical gap with a wave number of 1100 nm ^-1 (9.3 μ) or less is emitted from a ceramic heating element such as zircon ceramic (mainly). component
Photoexcitation is performed using a far infrared light source made of ZrSiO ₄ ). In addition, the Si--H absorption peak is 1100 to 70 for the production of insulators such as silicon oxide, silicon nitride, and silicon carbide.
It is at 0 cm ^-1 , and F is used to excite and cut this bond.
It is similarly effective by using the light energy of IR. Indium tin oxide (also called ITO) (SnCl bond, In
Since the infrared resonance absorption of Cl bond is 1000 to 600 cm ^-1, it is effective in the Photo CVD apparatus using the FIR of the present invention.

The features of the present invention will be described below in comparison with a conventional device with reference to the drawings. Figure 1 shows the previously known Ph
An outline of the oto CVD apparatus is shown.

In the drawing, a substrate (1) is arranged in a reaction vessel (2), and a heater (39) is used to cover the substrate 200 from the lower side.
It is heated to 400 ° C. Further, ultraviolet light (253 nm) is vertically irradiated (33) on the surface of the substrate (1) by a low-pressure mercury lamp (9) (output 10-40 W) through a quartz plate.
Oil (54) is applied to the lower side of the quartz plate (38) to reduce the adhesion of reaction products. The reactive gas is
Silane (26) is supplied from the doping system (20) from the flowmeter (29) through the valve (28) in parallel with the substrate surface (34). Hydrogen or helium as carrier gas (2
7), a photochemical reaction is performed, and a semiconductor film is formed on the substrate (1). The unnecessary reaction product and the carrier gas are exhausted to the outside from the vacuum pump (18) through the valve (13) for pressure adjustment.

In such a conventional apparatus, when a silicon film is formed of silane, silane is caused to flow from the direction of (34), ultraviolet light is vertically irradiated to the substrate, and surface reaction occurs on the substrate. A silicon film is formed. But if another board is placed in (1 '),
Due to (1 '), the surface of (1) is not irradiated with ultraviolet light,
It has become a shadow. Therefore, the photochemical reaction cannot be performed on the lower substrate (1).

That is, the conventional method cannot form a large amount of film on the substrate. In the conventional method, this photochemical reaction has been made based on the fact that the photochemical reaction on the surface of the substrate is rate limiting rather than the photochemical reaction in the reactive gas in flight. Therefore, the configuration other than that shown in FIG. 1 could not be adopted.

Further, in this method, since the light source is arranged in the atmosphere, damage to the quartz plate (38) due to pressure or the like is prevented, so that the area cannot be increased. Therefore, only one 3-inch wafer was used as a substrate, and theoretically, it was impossible to simultaneously insert five 5-inch wafers.

On the other hand, when plasma energy is applied in this method, the active molecules or ions are converted into oil (54).
The surface is sputtered, and as a result hydrocarbons of this oil are generated as impurities and mixed into the coating. For this reason, it has been an extremely serious obstacle in producing a non-carbide coating.

On the other hand, according to the present invention, as a result of thoroughly studying this Photo CVD method, ultraviolet light having a wavelength of 300 nm or less is not used, and infrared light is not used by a small area means such as carbon dioxide gas laser light. The continuous light with a wave number of 300 to 1500 cm ^-1 , which performs resonance absorption with the bond of the reactive gas, is sufficiently irradiated to the large space to form a film on the surface to be formed. Caused by
In addition, they have found that it is possible by using heat energy.

Further, in the present invention, FIR is used.
Since the photo-CVD method does not use the mercury-exciting method, which is harmful for pollution problems, the growth rate of the film is 0.1-
Only 0.3Å / sec (6Å / min ~ 18Å / min) was obtained. Therefore, in the device of the present invention, in addition to light energy, electric energy is supplied at the same time to promote activation of the reactive gas, and as a result, the growth rate of the film of the reactive gas is about 10 times or more 2 to 10 Å / sec. It is characterized by being able to be made large.

In the conventionally known plasma CVD,
Sputtering (damage) the substrate surface with plasma energy
Therefore, a Photo CVD method using no plasma at all has been devised in order to compensate for such a defect.

However, as a result of a thorough consideration of the plasma generation mechanism, the inventor of the present invention used discharge energy (glow discharge) alone, and most of the applied energy was used as collision energy.
It was found that only 3-10% of the reactive gas was ionized. Therefore, ion energy could be further increased by 2 to 4 times by adding FIR energy to a large amount of reactive gas which was not excited yet even though electron energy was used. In addition, by sufficiently reducing the light energy of the wave number required for resonance of OH or the like having a wave number of 3000 cm ^-1 or more, in the conventional PCVD method, silicon oxide or the like is mixed into the silicon by impurities of H ₂ O to improve the film characteristics. I was able to prevent making it worse. That is, it has become possible to prevent the defect that is apt to take in impurities, which is the largest defect other than damage in the conventional PCVD method, and selectively mix water oxygen into the film sufficiently. .. The present invention is 1500 cm ^-1
In particular, it has become possible to purify and purify a reactive gas that resonates and absorbs a wave number of 1100 cm ^{-1 as} a constituent component of a film, that is, when forming a film.

Further, in the PPCVD method of the present invention,
The discharge energy is weakened to reduce damage, but to facilitate the start of discharge associated with this and to prevent the instability in which this discharge is likely to stop even after it has once been discharged, plasma energy alone is used for ionization. It is an instantaneous application of FIR that resonates with an unusable bond. As a result, it is characterized by facilitating the start of discharge and sustaining the discharge at a particularly high voltage (1 to 50 torr).

Photo CV of the present invention will be described below with reference to the drawings.
Note the D device. FIG. 2 shows an outline of an apparatus for carrying out the photo-CVD method of the present invention in which the reaction system is the CVD (PPCVD or Photo CVD) method.

[0024]

【Example】

Example 1 FIG. 2 has a reaction system (10), a doping system (20) and an exhaust system (30). The reaction system (10) is the reaction vessel (2)
(Internal volume, width 100 cm, height 60 cm, depth 100 cm Reaction space 65
cm × 65 cm × 25 cm, 105625 cm ² ), the substrate (1) having the formation surface is held by the holder (31). This holder is 65 cm x 65 cm, but it is in the reactive gas flow direction (34).
Twenty (20) cm (60 cm) substrates having a length of 25 cm (total area of the formation surface: 24000 cm ² ) are simultaneously inserted.

Further, the surface of the substrate (1) on which the reactive gas is formed is vertically forested at regular intervals (1 to 10 cm, eg 5 cm) along the flow of the reactive gas introduced from above and discharged downward. I am letting you. The substrate is heated to, for example, 200 to 500 [deg.] C. by a halogen auxiliary heater (7) above and below the quartz hood (54) (emission wavelength of 1 to 3 [mu]) in addition to the ceramic heating element (9). A FIR heating element (9) for photochemical reaction that emits a wave number of 1500 cm ^-1 (6.65 μ) or less, especially 1100 (9.3 μm) to 500 cm ^-1 (20 μm) is used as an upper light source and a lower light source in the reaction furnace. It is provided in. This lamp zircon is (main component ZiSiO ₄₎ ceramics, by heating the zircon inside allowed heating at Nichrome, 1500 cm ^-1 especially 1100 as the ceramic heating element ^{(9.3 μm) ~500 cm -1 (} 20μm) The wave number of infrared (FIR) generation is made with high output. Further, this ceramic heating element has another feature that, even if a reaction product is formed on the ceramic surface of the luminescent material, this product transmits FIR light, and therefore, under atmospheric pressure outside the reaction furnace. It has become possible to arrange it in the reaction furnace instead of the above.

In FIG. 3, the horizontal axis has the wave number (the reciprocal of the wavelength),
The vertical axis shows the transmittance graph and the normalized emission intensity of FIR. In the drawing, the absorption intensity (51 ') in the transmittance graph shows the absorption of silane, and the emission intensity graph shows the FIR emission wavelength spectrum of the zircon ceramic heating element.

A curve (50) shows the emission spectrum intensity of the zircon ceramic heating element used in this example of the present invention. This emission is due to the absorption spectrum (51) of the silane used in this example, especially the absorption peak (11) of the bending vibration of Si--H.
Matches 00-800 cm ^-1 ) (51 '). Therefore FIR
Is effective in decomposing silane.

Furthermore, in the present invention, the reactive gas flow (34) and the irradiation light are arranged in parallel or substantially parallel to the substrate surface, and the irradiation light irradiates the entire reaction space (32). In particular, since FIR has a large wraparound of light, it is preferable for mass production in a large space as compared with the case of using ultraviolet light or the like. The reactive gas reaches the reaction space (32) through the inlet (11), the nozzle (3), and the exhaust system (12) through the quartz outlet (8). The exhaust system (30) consists of a pressure regulating valve (13), a stop valve (14), a mechanical booster
Pump (17) Use the rotary pump (18) to discharge waste materials to the outside. The substrate is placed in the quartz holder first in the preliminary chamber (1
After arranging in (6) and vacuuming at (22) and (23),
The gate (37) was opened and transferred to the reaction space (55).
The reactive gas is silane (26) in the doping system (20), other reactive gas for P type such as diborane (B ₂ H ₆ ) or N type gas such as fossine (PH ₃ ). 2
4), Gas such as ammonia or methane for adding nitrogen or carbon to silicon (25) Hydrogen or helium (27) as a carrier gas is controlled by a valve (28) via a flow meter (29). Then added.

The reactive gas made of silane for the silicon semiconductor reaches the reaction system (10) through (26) and the flow meter (29). This reaction system has a temperature of 100 to 500 ° C, preferably 200 to 35 ° C.
A substrate having a surface to be formed, which is maintained at 0 ° C, typically 300 ° C, is provided, and the pressure in the reaction space (32) is 0.01 to 10
As torr, for example, 2 torr, the silane flow rate is 1 to 500 cc /
For example, 60 cc / min was supplied. The light energy is FIR
Six lamps (length 680mm, 16mm, maximum output 500W) that emit long wavelength light with a wave number of 1100 cm ^-1 or less (total 3K
W) was used for light irradiation to perform Photo CVD. Next, the electric energy is fed into a high frequency oscillator (frequency 100 KHz or 13.56 M
(Hz) (4) and a pair of electrodes (5) and (6), and plasma glow discharge was performed to carry out a PPCVD reaction.

The surface of the substrate is disposed parallel to the irradiation light for photochemical reaction, and the photochemical reaction is 150 to 35 by the flying halogen lamp, not by the surface of the substrate.
It was carried out on a reactive gas which had been preheated to 0 ° C., eg 300 ° C.

By doing so, it is possible to prevent the irradiation light from becoming the shadow of the substrate and not to be irradiated to the reactive gas on the opposite side, and photo CVD and PP capable of mass production can be produced.
The CVD could be carried out. Furthermore, in the device of the present invention, the reactive gas is preheated to approximately the same temperature as the substrate, and the heated reactive gas is photoexcited, so that sufficient film formation is achieved even if the surface of the substrate is not irradiated with light. It also has the feature that it is possible.

The growth rate of this semiconductor film is Photo CV
In the case of D alone, it was 0.1 to 0.3Å / sec, for example, 0.2Å / sec. That is, in the Photo CVD method using FIR, the surface of the substrate was not damaged by plasma, so that good film quality could be obtained. However, the growth rate of the coating is extremely low at 0.1 to 0.3 Å / sec, and the light energy required therefor is extremely strong.

On the other hand, although PPCVD using FIR in the present invention shows some damage due to plasma, the growth rate of the film is 1 to 6 Å / sec, which is 10 times faster than that of the Photo CVD method. I was able to. This PPCV
In the D method, thermal energy is applied to the reactive gas as the order of the steps, and further FIR light irradiation is performed in advance,
It is extremely important that a part of the reactive gas is photoexcited to make it extremely easy to ionize, and then electric energy is applied to cause a plasma reaction. By doing so, it was possible to start the discharge at a low power supply voltage, prevent the generation of plasma shock waves, and substantially prevent the plasma damage on the substrate surface.

As described above, a non-single-crystal semiconductor containing silicon as a main component and having an oxygen concentration of 1 × 10 ¹⁸ cm ^-3 or less, which is shown by the method of the present invention, could be formed on the formation surface. When the film quality of this silicon film was examined, the oxygen concentration was 1 × 10 ¹⁸ atom / cc or less in the SIMS measurement (light output 3.0 KW or less, discharge output 28
(0W or less).

Further, when the discharge output is 150 W, 3 × 10 ¹⁷
atom / cc and further reduced to 1/3 of that, silane, which was conventionally known, was connected to the doping system, and it was produced by the PCVD method (CVD method using only plasma), and the oxygen content in the film was changed. Examination revealed that it was 3 × 10 ¹⁹ atom / cc, which was reduced to about 1/10 or less than this value.

In the apparatus of the present invention, the substrate temperature is 350 ° C.
The crystallinity of the coating film formed at 400 ° C. further advanced. The temperature at which the reaction product was produced was not limited to 300 ° C. in the PPCVD method, but could be 150 to 300 ° C. In the Photo CVD method, since the film growth rate is increased, it is possible to obtain a low oxygenated polysilane (for example, Si ₂ H ₆ ) instead of monosilane described above. This polysilane, in particular the silane containing at least part of disilane (concentration of 5 to 30%), is used to obtain the Ph
When a semiconductor film was formed by the oto CVD method, the film growth rate could be increased to 2Å / sec, which is about 10 times that in the photo CVD method of monosilane.

FIG. 4 shows a glass substrate on which 0.5 is applied by the apparatus of FIG.
The μ silicon semiconductor layer is formed by the PPCVD method (optical output 3.0 KW).
(125 mW / cm ² ) (3000 W / 24000 cm ² discharge output is 150 W)
It was made in. After that, an ohmic contact electrode was provided as a parallel electrode in this portion, and the electrical conductivity characteristics were investigated. FIG. 4 particularly shows the electrical characteristics of a low-oxygenated silicon semiconductor using silane by the PPCVD method of the present invention. (56) (64) (65) (66) (68) Conventional PCVD reaction characteristics
(57) (63) (58) (67) (69) are compared with each other to show the results of examining the light irradiation effect and the thermal annealing effect.

In the drawing, the area (59) in the conventional example
Indicates dark electric conductivity (57) and has a value of 3 × 10 ⁻⁸ (Ωcm) ⁻¹ . When AM1 (100 mW / cm ² ) is irradiated here in the area (60), it has 1 × 10 ^-4 (Ωcm) ^-1 in the conventional method as shown by the curve (58), and is continuously irradiated for 2 hours. The value was deteriorated by about one digit.

On the other hand, the semiconductor film formed by the PPCVD method of the present invention has a dark conductivity (56) of 5 × 10 ^-11 (Ωc).
m) ^-1 and its photoconductivity (64) is 6 × 10 ^-5 (Ωcm)
^{It has an order of 1} and a photosensitivity of 10 ⁶ and is about two orders of magnitude larger than the conventional example. No deterioration in conductivity was observed. This is the Photo of the present invention
This data proves that CVD and PPCVD were able to reduce the mixing of oxygen.

Further, in the region (61), the dark conductivity after irradiation was also the same within the error range as compared with (66) and (56) in the present invention. When heating at 150 ℃ for 2 hours, the curve (67) becomes (69) in the conventional example, and there is an apparent change in characteristics. It was seen.

In the present invention, however, the electric conductivity is hardly changed or deteriorated depending on the presence or absence of light irradiation and the presence or absence of thermal anneal, and the photoconductivity and photosensitivity (photoconductivity and darkness) are obtained. The difference with the conductivity) was large, and the dark conductivity was small.

As described above, it has been found that the method of the present invention has a synergistic effect that a highly reliable silicon semiconductor layer can be provided. Of the present invention
With the Photo CVD and PPCVD equipment, sputter (damage) effects are virtually eliminated and mass production is possible. As a result, the PN or PIN junction can be applied to a photoelectric conversion device, an optical sensor, an electrostatic copying machine, an insulating gate type field effect semiconductor, and an integrated device thereof, which is considered to be extremely effective industrially.

[Embodiment 2] This embodiment shows a case of producing a silicon nitride insulator. The device was made using FIG. FIR light having an emission wave number of 1100 cm ^-1 or less was used as a light source for the photochemical reaction. In Figure 2, purified silane (26)
Further, ammonia was supplied from (25) as NH ₃ / SiH ₄ > 50. The absorption of amine has a strong absorption peak at 700 to 900 cm ^-1 . The Si--H and NH (NH ₂ ) could be reacted effectively.

As a result, in the photo CVD method,
We were able to make 1 Å / sec insulating silicon nitride film. Further, the PPCVD method was applied with the same electric energy output as in Example 1 to obtain a film growth rate of 4.3 Å / sec at a substrate temperature of 250 ° C.
It was possible to obtain it at a pressure of 2 torr. As a result of investigating C-V characteristics by forming a film thickness of 1000Å on a silicon single crystal semiconductor substrate, it was possible to obtain an interface charge density of 1 × 10 ¹¹ cm ^-2 or less. Further, even when an electric field strength of 2 × 10 ⁶ V / cm was applied, no hysteresis phenomenon was found in the CV characteristics, and it was found that the semiconductor surface was scarcely sputtered (damaged).

[Embodiment 3] This embodiment is an example of forming a silicon oxide film by the apparatus of the present invention. The apparatus is the same as in Example 2. N ₂ instead of ammonia as reactive gas
O 2 was used and introduced from (25). Furthermore, silane was introduced from (26) as N ₂ O / SiH ₄ > 20. As for the obtained results, no hysteresis was observed in the C-V characteristics as in Example 2. Further, it had a dielectric strength of 1 × 10 ⁶ V / cm.

Example 4 In this example, ITO (indium tin oxide, tin oxide was used in an amount of 10% by weight or less, for example, 5%).
This is the case of forming indium oxide) which is contained by weight. The same device as in Example 2 was used. When this InCl is used, the In-Cl bond has a strong absorption at a wave number of 700 to 800 cm ^-1 , and thus Photo CVD can be carried out similarly to the Si-H bond. As reactive gas, indium chloride was added from (26) and NO was added from (25). Further (24)
In order to reduce the sheet resistance of the formed indium oxide, tin tetrachloride was added, and nitrogen was added as a carrier gas from (27).

Thus, indium oxide or ITO
It could be obtained at 100-500 ° C, for example 300 ° C. The film formation rate is 7Å / sec at 2 torr by PPCVD method.
It could be made at 1 torr and 300 ℃. Seat resistance is 70
The film thickness was 0 Ω / □, and the transmittance was 87%.

Example 5 In this example, a transparent conductive film of tin oxide was prepared. The equipment was the same as in Example 4. As reactive gas, tin chloride was added from (24) and N ₂ O was added from (25) as N ₂ O / SnCl ₄ > 20. At the same time CF from (26)
By adding ₃ Br, the sheet resistance is 50Ω / □ or less (thickness 1000Å
In the case of). 1200 to 1350 cm ^-1 , C for C-F
--Cl has a strong absorption peak at 1000 to 1200 cm ^-1, and C
--Br has a strong absorption peak at 500 to 650 cm ^-1 . Therefore, CF ₃ Br is used for the Photo CVD, P of the present invention by using FIR.
It was effective to add PCVD as an impurity.
The value is 1KΩ / □ to 3KΩ / □ without addition of halogen element
However, the sheet resistance could be reduced to 50 to 200 Ω / □.

The formed film was further baked at 500 ° C. in an N ₂ O atmosphere or a mixed atmosphere of oxygen and nitrogen while applying irradiation light for photochemical reaction. Thus, a tin oxide film having acid resistance and plasma resistance could be obtained. This tin oxide film is formed on a transparent insulating substrate such as a glass substrate, or IT on the glass substrate shown in the first embodiment.
Layered on O as a coating material, ITO (300-1500)
Å) and SnO ₂ (200-400 Å) were also effective as a two-layer structure.

In the above examples, the FIR was 3 KW (light energy density 28 mW / cm ² ). But this is 50 ~
Photo CVD as 200 mW / cm ³ and light energy density
It is effective to improve the growth rate of the coating film in the above step, reduce the discharge output in the PPCVD method, and further reduce the spatter.

In the above description of the present invention, Photo CVD is not performed in a small area such as carbon dioxide gas laser, but Photo CVD is used to form a film having a large area 10 times or more that of the above.
It was found that it became possible to form a film by the method or PPCVD method.

As is clear from the above description, in the present invention, the reactive gas is caused to flow downward from above, and the substrate is vertically (vertically) arranged so that the falling flakes do not adhere to the surface on which the substrate is formed.
The forest is forested with a space (1 to 10 cm, for example 5 cm) open between them, and the periphery of this reaction space is surrounded by a holder so that the reactive gas does not enter the space other than the reaction space.

Further, in order to prevent one substrate from being shaded by another substrate, the surface of this substrate is irradiated with light in parallel so that the reactive gas is photoexcited during flight,
As a result, as shown in the embodiments of the present invention, 20 cm × 60 cm substrates can be inserted into 20 / lot or 100 / lot like a 5 inch size silicon substrate. We believe that it will be possible to mass produce up to 20 times as many as five pieces, and the industrial effect will be extremely large.

[Brief description of drawings]

FIG. 1 shows an outline of a conventional Photo CVD device.

FIG. 2 shows an outline of a Photo CVD and photo plasma CVD apparatus using the method of the present invention.

FIG. 3 shows emission characteristics and absorption characteristics of Si—H 2 system of the zircon lamp for FIR used in the present invention.

FIG. 4 shows electric conductivity characteristics obtained by the method of the present invention and a conventional example.

Claims (1)

[Claims] 1. A method of irradiating a reactive gas with light for photochemical reaction which causes photoexcitation or photochemical reaction to a reactive gas and does not absorb a reaction product or has a small wave number. A characteristic method for producing a coating film.