JPS6027121A - Photo chemical vapor deposition device - Google Patents

Abstract

PURPOSE:To enable the mass processing by photo CVD or photo PCVD methods by providing a light source in a reactor for projecting the light whose wavenumber is 1,500cm<-1> or less and capacity coupling type electrodes, thereby causing a plasma reaction. CONSTITUTION:A substrate 1 is arranged in a reactor 2 with being held by a holder. The reactive gas is sent from a doping system 20 to a reaction system 10. A ceramic light emitting member 9 emits the continuous light whose peak light is the far infrared ray of 1,500cm<-1> or less wavenumber. The far infrared rays and reactive gas are projected to a surface of the substrate 1 in parallel. Next, the electric energy is applied from a high-frequency oscillator 4 through electrodes 5 and 6. Then, the reactive gas becomes easy to be ionized by light irradiation and plasma reaction is performed by plasma glow discharge between electrodes 4 and 5. At this time, the far infrared rays can encroach widely and are projected over a wide space so that a plurality of substrates can be processed at a time.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses a photo-filled phase method (hereinafter simply referred to as FIR) using far infrared light (hereinafter simply referred to as FIR) with a wave number of 300 to 1500 cm', preferably 500 to 1100 cm'.
(hereinafter referred to as Pl+oto CVI) or optical plasma vapor method (r'hoto Plasma Chemical
This invention relates to an optical CvD device (photochemical vapor phase application device) that can be mass-produced using VaporDiposition (hereinafter referred to as 1cV D).

This invention emits light with a wave number of 1500 cm-1 or less more intensely than light with a wave number of 1500 cm-1 or less, and in particular heats the light that is emitted as continuous light with a peak light at a wave number of 1100 cm-1 or less. It is characterized by its use as a light source for Photo CVD.

Therefore, the present invention is characterized in that a ceramic heating element is used instead of a laser beam for the FIR, and a wide space within the reactor is irradiated with light.

Conventionally, in the CVD method, a substrate having a surface to be formed is heated from below the substrate, and the surface to be formed, which is the upper surface of the substrate, is irradiated with ultraviolet light from outside the reactor in a vertical direction. A known method is to perform photoexcitation by irradiating a reactive gas on the surface with light to cause a photochemical reaction.

This conventional method had a major industrial drawback in that it was not possible to provide a surface to be formed with a size equal to or larger than the area of the irradiated light.

Furthermore, when trying to form silicon using silane, for example, some of the photo-excited silicon adheres to the light irradiation window and absorbs the irradiation light. This had the disadvantage of significantly weakening the strength.

Furthermore, quartz glass, which is generally used as a window material, has a
Far infrared light of 0 nm or less and wavelength of 3.5 μ or more (30
It has the disadvantage that it cannot transmit far-infrared light with a wave number of 00 cm" or less.

For this reason, although the FO1-CVD method has the advantage of not damaging the substrate surface, it has been completely impossible to apply it to mass production using the direct excitation method.

The present invention eliminates these drawbacks and proposes a claw 1-CVD apparatus that can be industrially mass-produced for the first time.

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 wavenumbers that do not or have little absorption of the irradiated light.

Therefore, in the present invention, in a semiconductor whose main component is silicon, an optical gear with a wave number of 11l100n' (9,3μ) or less is used. (Main component Zr 5t%) is used for optical excitation using a far-infrared light source.Also, for the production of insulators such as silicon oxide, silicon nitride, and silicon carbide, the absorption peak of 5i-H is 1100 ~ 700 cm-', and it is similarly effective to use Fll? light energy to excite and cleave this bond.Also, it is effective to use optical energy of Fll? to excite and cleave this bond.It is also effective to use light-transmitting conductive materials such as tin oxide, also called indium tin oxide CITO. Also in the film, since the infrared resonance absorption of 5nC1 bond and InCl bond is in the range of 1000 to 600 cm'-', the Fl of the present invention
l? It is effective in Photo CVD equipment using

The features of the present invention will be described below in comparison with conventional devices according to the drawings.

FIG. 1 shows an overview of a conventionally known PhotoCvD apparatus.

In the drawing, a substrate (1) is placed inside a reaction vessel (2) and heated to 200 to 400°C from below by a heater (39). Furthermore, ultraviolet light (253 nm) is irradiated (33) perpendicularly onto the surface of the substrate (1) through the quartz plate using a low-pressure mercury lamp (9) with an output of 10 to 40 W. Oil (54) is applied to the lower side of the quartz plate (38) in order to reduce the adhesion of reaction products.The reactive gas is silane (26) than the doping system (20), which is passed through the flowmeter ( Hydrogen or helium as a carrier gas is supplied from (27) in parallel to the substrate surface (50) through a valve (28), and a photochemical reaction occurs to form a semiconductor film on the substrate (1). Unwanted reaction products and carrier gas are formed, and the valve for pressure regulation (
13) and is exhausted to the outside by a vacuum pump (18).

In such conventional equipment, when a silicon film is formed using silane, the silane is flowed from the (5o) direction, and ultraviolet light is irradiated perpendicularly to the substrate, causing a surface reaction on the substrate to cause the silicon film to form. It is formed.

However, if another board is placed at (12), then (1)
As a result, the surface of (1) was not irradiated with ultraviolet light and was in the shadow. Therefore, no photochemical reaction can occur on the lower substrate (1).

That is, with the conventional method, it is not possible to form a large amount of film on the substrate. In conventional methods, this photochemical reaction is based on the fact that the photochemical reaction on the substrate surface is rate-determining, rather than the photochemical reaction with the reactive gas in flight. For this reason, configurations other than those shown in FIG. 1 could not be adopted.

Furthermore, in this method, since the light source is placed in the atmosphere, it is impossible to make the area large in order to prevent damage to the quartz plate (38) due to pressure or the like.

For this reason, only one 3-inch wafer was required as a substrate, and even theoretically it was impossible to insert five 5-inch wafers at the same time.

On the other hand, when plasma energy is added in this method,
The active molecules or ions sputter onto the oil (54) surface, resulting in generation of the oil's hydrocarbons as impurities and mixing into the coating. This has been an extremely large obstacle when attempting to produce a non-carbide film.

On the other hand, as a result of thorough study of this Photo CVD method, the present invention has developed a method for bonding reactive gases, rather than using ultraviolet light with a wavelength of 300 nm or less, or using infrared light using a small area means such as carbon dioxide laser light. This is made possible by sufficiently transmitting continuous light with a wave number of 300 to 1500 cm' that resonates with hands into a large space, generating a film on the surface of the film using an FIR ceramic heating element, and using thermal energy in addition. I found out.

Furthermore, in the present invention, Photo using FIR.

Since the CVD method does not use mercury excitation, which is harmful to pollution problems, the growth rate of the film is 0.1 to 0.
Only 3 people/second (6 people/minute to 18 people/minute) were obtained.

For this reason, in the apparatus of the present invention, electric energy is supplied in addition to light energy at the same time to promote the activation of the reactive gas, thereby increasing the growth rate of the reactive gas film by about 10 times or more. The feature is that it can be enlarged in seconds.

Conventionally, in known plasma CVD, the substrate surface is sputtered (damaged) by plasma energy, and in order to compensate for this drawback, a Photo CVD method that does not use plasma at all has been devised.

However, as a result of careful consideration of the plasma generation mechanism, the inventor of the present invention found that most of the energy applied by discharge (glow discharge) alone is used as collision energy, and only 3 to 10% of the reactive gas is ionized. It has been found. For this reason, FlI? By adding the energy of In addition, by sufficiently reducing the optical energy of the wave number necessary for resonance of OH, etc. with a wave number of 3000 cm' or more, in the conventional PCVD method, silicon oxide etc. are mixed into the silicon due to impurities of H2O, which deteriorates the film characteristics. could be prevented. In other words, it has become possible to prevent the disadvantage of the conventional PCVD method other than damage, which is the tendency to incorporate impurities, and to selectively sufficiently reduce the incorporation of oxygen from water into the film. . The present invention is 1500
It has also become possible to specifically select a reactive gas that resonates and absorbs wave numbers of c+n-', especially 1100 cm-', and purify it at the time of forming a so-called film as a component of the film.

Furthermore, in the PPCVD method of the present invention, the discharge energy is weakened in order to reduce damage, but this also makes it easier to start the discharge, and also reduces the instability where the discharge is likely to stop even after it has started. To prevent this, FIR that resonates with bonds that cannot be ionized by plasma energy alone is instantaneously applied. As a result, it is characterized by the fact that it is easy to start the discharge especially at high voltage (1 to 50 torr), and it is also easy to sustain the discharge.

The Photo CVD apparatus of the present invention will be described below according to the drawings.

Figure 2 shows that the reaction system is CVD (PPCVD or Photo).
o CVD method, and an outline of an apparatus for carrying out the photo-CVD method of the present invention is shown.

Example 1 FIG. 2 shows a reaction system (10), a doping system (20), and an exhaust system (30).

The reaction system (10) has a reaction container (2) inner volume of +131
00cm, height 60cm, depth 100cm reaction space 65cm x 65cm x 25cm, 105625 c
+a), a substrate (1) having a surface to be formed is placed in a holder (3).
1) is maintained.

This holder is 65 cm x 65 cm but has a length of 25 cm in the direction of flow of the reactive gas (34) and a length of 20
20 substrates (cm x 60 cm) (total surface area to be formed 24000 cJ) are inserted at the same time.

Furthermore, the formation surface of the substrate (1) is arranged in a forest at regular intervals (1 to 10 cm, for example 5 cm) in the vertical direction along the flow of the reactive gas introduced from above and discharged downward. .

In addition to the ceramic heating element (9), the board includes a quartz hood (
54) Heated to, for example, 200 to 500°C by upper and lower halogen auxiliary heaters (7) (emission wavelength 1 to 3μ). Wave numbers below 1500 cm' (6,65, CZ), especially 1100 (9,3, Ll) to 500 cm
14 for photochemical reactions that emit light at a wavenumber of -' (20μ)
An R heating element (9) is provided in the reactor as an upper light source and a lower light source.

This lamp is made of zircon (main component: ZiSi%) ceramic, and by heating the zircon with nichrome inside, it can be used as a ceramic heating element.
00cm' especially 1100 (9,3μ) ~ 500cm"
Infrared rays (FIR) with a wavenumber of (20μ) were generated at high output. Another feature of this ceramic luminescent material is that even if a reaction product is formed on the ceramic surface of the luminescent material, this product will transmit light through the FIR. It is now possible to install the reactor inside the reactor instead of from inside the reactor.

The emission spectrum of the zircon ceramic heating element used in this example of the present invention is shown in curve (51) in FIG. This luminescence is caused by the Si-[1
Absorption peak of bending vibration (1100~800cm-1
), indicating that FIR is effective for the photodecomposition reaction of silane.

Furthermore, in the present invention, the reactive gas flow (34)
, the irradiation light is arranged parallel or substantially parallel to the substrate surface,
The irradiation light irradiates the entire reaction space (55). In particular, FIR has a large amount of dust surrounding the light, so it is preferable for mass production in a large space compared to the use of ultraviolet light or the like.

The reactive gas flows from the inlet (11) through the nozzle (3) to the reaction space (55), and through the quartz outlet (8) to the reaction space (12).
) to the exhaust system.

The exhaust system (30) includes a pressure adjustment valve (13), a stop valve (14), and a mechanical booster pump (17).
.

The rotary pump (18) discharges waste materials to the outside.

The substrate was first placed in the preliminary chamber (16) using a quartz holder, and after vacuuming was performed at (22> and (23>), the gate (37) was opened and the substrate was moved to the reaction space (55). Ta.

The reactive gas is a doping system (20〉) in which silane (26
), other P-type reactive gases such as diporane (BLH), or N-type reactive gases (24
), a gas such as ammonia or methane (25) for adding nitrogen or carbon to silicon, and hydrogen or helium (27) as a carrier gas are each controlled by a valve (2) through a flow needle (29). can be added as

The reactive gas for silicon semiconductors consisting of silane is (26)
It then passes through the flow meter (29) and reaches the reaction system (1O).

This reaction system is heated at a temperature of 100 to 500℃, preferably 200 to 3℃.
A substrate having a surface to be formed is maintained at 50°C, typically 300°C, and the pressure in the reaction space (32) is reduced to 0.
．． OI to 10 torr, for example 2 torr, and a silane flow rate of 1 to 500 cc for 7 minutes, for example 60 cc/min, was supplied. The light energy is FIR, and a lamp (length 6
80 mm, 16 mm, maximum output 500 W) were used for light irradiation using six (31 in total) to perform r'l+oLo CVD. Next, the electrical energy is transmitted to a high frequency oscillator (frequency 10
0KHz or 13.56MIIz) < 4. ), a pair of electrodes (5) and (6) were used, and a plasma glow discharge was applied to perform the PPCVD reaction.

The surface of the substrate is placed parallel to the irradiation light for photochemical reaction, and the photochemical reaction is preheated to 150 to 350°C, for example, 300°C, by a halogen lamp in flight rather than on the substrate surface. Performed for reactive gases.

By doing this, it is possible to prevent the irradiated light from being behind the substrate and not irradiating the reactive gas on the opposite side.
Photo CVD and PPCV [
I was able to implement 1. 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 excited by light, so that a film can be formed sufficiently even if the surface of the substrate is not irradiated with light. It also has the advantage of being possible.

The growth rate of this semiconductor film was 0.1 to 063 people/second, for example, 0.2 people/second when using only Photo CVD. That is, in the Photo CVD method using FIR, good film quality could be obtained because the substrate surface was not damaged by plasma. However, the growth rate of the film is extremely slow at 0.1 to 0.3 persons/second, and the light energy required for this growth is extremely strong.

On the other hand, in the PPCVD method using FIR according to the present invention, some damage due to plasma is observed, but the film growth rate is 1 to 6 people/second, which is 10% faster than the Photo CVD method.
We were able to grow twice as fast. In this PPCVD method, the sequence of steps is to apply thermal energy to the reactive gas and then irradiate it with FIR light in advance, so that a part of the reactive gas is photoexcited and ionized very easily, and then electrical energy is applied. In addition, it is extremely important that a plasma reaction is generated. By doing this, it becomes possible to start the discharge with a low power supply voltage,
Furthermore, generation of plasma shock waves could be prevented, and plasma damage to the substrate surface could be substantially prevented.

As described above, a non-single-crystal semiconductor having silicon as a main component and having an oxygen concentration of I x 10I1018'' or less, as shown by the method of the present invention, could be formed on the surface to be formed.

Examining the film quality of this silicon film, we found that the oxygen concentration was less than I x 1101 Ilato/cc (
It was possible to provide a light output of 3.0 KW or less and a discharge output of 28 KW or less.

Furthermore, if the discharge output is 150W, 3 x 10 ports a t
om/cc and further reduced to 1/3 of that, connecting a conventionally known silane to a doping system, producing it by the PCV [) method (CVD method using plasma), and reducing the oxygen content in the film. When we look up , we find that 3 XIO' atom/
cc, and it was found that this value was reduced to about one-tenth or less.

In the apparatus of the present invention, the crystallinity of the formed film further progressed by increasing the substrate temperature to 350°C and 400°C.

In the PPCVD method, the temperature for producing this reaction product is 3.
It was possible not only at 00°C but also at 150 to 300°C.

In the Photo CVD method, in order to increase the film growth rate, a low oxygen polysilane (for example, S tLt14') can be obtained as the silane instead of the above-mentioned monosilane. When producing a semiconductor film by the Photo CVD method described above using this polysilane, especially a silane containing disilane in at least a portion (concentration of 5 to 30%), the growth rate of the film is set to 2 people/second and the photo CVD method of monosilane is used. We were able to increase this to about 10 times that of the law.

Figure 4 shows a 0.5μ silicon semiconductor layer formed on a glass substrate using the apparatus shown in Figure 2 using the PPCVD method (light output 3.0KW').
) (125mW/cJX3000W/24000c+
a The discharge output was 150 W).

Thereafter, an ohmic contact electrode was provided as a parallel electrode in this portion, and the electrical conductivity characteristics were investigated.

Figure 4 particularly shows the electrical characteristics (56 pieces (64)) of a low oxygen silicon semiconductor using silane by the PPCVD method of the present invention.
, <65>, (66), <68), conventional PCVD
Characteristics due to reaction (57), (63), (58), (67
), <69), and the results of examining the light irradiation effect and thermal annealing effect are shown.

In the drawing, in the conventional example, the region (59) exhibits dark electrical conductivity (57), which is 3×10″B(QCIll)−’
It has the value of . Here AMI (100mW/c
When irradiating area (60) with J), in the conventional method, the curve (
As shown in 58), it had lXl04(Ωcm)-', and its value deteriorated by about one order of magnitude after continuous irradiation for 2 hours.

On the other hand, the semiconductor film produced by the PPCVD method of the present invention has approximately conductivity (56) of 5 x 10" (ocm
)-', and its optical conductivity (64) is 6X10'(Ω
It has an order of cm)-' and a photosensitivity of 10G, which is about two orders of magnitude larger than that of the conventional example. Furthermore, when irradiated with continuous light, as seen in curve (65), it is extremely However, no deterioration in electrical conductivity was observed.

This data proves that Photo CVD and PPCVD of the present invention can reduce oxygen contamination.

Furthermore, in the present invention, the dark conductivity of region (61) after irradiation was also the same within the range of error compared to (66) and (56).

When heating at 150℃ is further performed for 2 hours, the curve (67) in the conventional example becomes (69), and there is an apparent change in the characteristics as shown above.After that, when the area (62) is irradiated with light again, it deteriorates again. Characteristics were observed.

However, in the present invention, the electrical conductivity depends on the presence or absence of light irradiation.
Almost no change or deterioration of properties was observed with or without thermal annealing, and photoconductivity and photosensitivity (difference between photoconductivity and dark conductivity) were large, and dark conductivity was small.

As described above, it has been found that the method of the present invention has a synergistic effect in that it can provide a silicon semiconductor layer having high reliability.

The Photo CVD and PPCVD apparatuses of the present invention have virtually no sputtering (damage) effects and can be produced in large quantities. As a result, the PN or PIN junction can be applied to photoelectric conversion devices, optical sensors, electrostatic copying machines, insulated gate field effect semiconductors, and integrated devices thereof, and is considered to be extremely effective industrially.

Example 2 This example shows the case of manufacturing a silicon nitride insulator.

The apparatus was constructed using Figure 2.

FIR light having an emission wave number of 1100 c, m'' or less was used as a light source for the photochemical reaction.

In FIG. 2, purified silane was fed from (26) and ammonia was fed from (25) at NI%/SiH4>50.

The absorption of amine has a strong absorption peak at 700-900 cm'. This SiH+ and NH (NH2) could be reacted effectively.

As a result, in the photoCvD method, it was possible to form an insulating silicon nitride film at a rate of 0.1 per second. Furthermore, PP
The CVD method was carried out using the same electrical energy output as in Example 1.
A film growth rate of 4.3 persons/second could be obtained at a substrate temperature of 250° C. and a pressure of 2 torr.

As a result of forming a film with a thickness of 1000 mm on a silicon single crystal semiconductor substrate and examining the C-■ characteristics, it was possible to obtain an interfacial charge density of IXIO''cm''2 or less in both cases. Furthermore, even if an electric field strength of 2 XIO' V/cm is applied, C
-■ No hysteresis phenomenon was found in the characteristics, and it was found that the semiconductor surface was hardly spattered (damaged).

Example 3 This example is an example in which a silicon oxide film was produced using the apparatus of the present invention. The apparatus is the same as in Example 2.

Calcium was used instead of ammonia as the reactive gas (25
) was introduced. Furthermore, silane is added from (26) to Np/
It was introduced as S i H i〉20. As in Example 2, no hysteresis was observed in the C-■ characteristic. Furthermore, it had a dielectric strength of I XIO' V/cm.

Example 4 In this example, ITO (indium tin oxide, indium oxide containing 10% by weight or less, for example 5% by weight, of tin oxide) was formed.

The same equipment as in Example 2 was used. When using this InCl, the In-Cl bond is 700 to 800 cm −' (7
) Phot as well as the 5t-H bond because strong absorption appears at the wave number.

CVD could be performed. As a reactive gas (
Add indium chloride from 26), NO from (25)
added. Furthermore, in order to lower the sheet resistance of the indium oxide formed from (24), tin tetrachloride was added,
Furthermore, nitrogen was added as a carrier gas from (27).

Thus indium oxide or ITO is
It could be obtained at 0°C, for example 300°C.

The coating was formed at a rate of 7 persons/second at 1 torr and 300° C. using the PPCVD method.

Sheet resistance is 25Ω/mouth with a film thickness of 700 people, and transmittance is 87.
%Met.

Example 5 In this example, a transparent conductive film of tin oxide was produced.

The equipment was the same as in Example 4.

Using tin chloride as a reactive gas (24), N and O (
25), it was added as Nρ/5nC1,>20.

At the same time, C'3Br was added from (26) to lower the sheet resistance to 50 Ω/4 or less (in the case of a thickness of 1000 people).

1200-1350cm-' for C-F, C-Y
has a strong absorption peak at 1000-1200 cm',
Furthermore, C-Br has a strong absorption peak at 500 to 650 cm. Therefore, CF3Br is subjected to Photo CVD of the present invention using FIR.

Adding it as an impurity to PPCVD was effective. The sheet resistance was able to be lowered to 50 to 200 Ω/mm, whereas it was IKΩ/mm to 3 Ω/mm without the addition of a halogen element.

The formed film is further exposed to irradiation light for photochemical reaction in an Nρ atmosphere or a mixed atmosphere of oxygen and nitrogen for 55 minutes.
It was fired at 00°C.

In this way, a tin oxide film having acid resistance and plasma resistance could be obtained. This tin oxide film can be applied to a light-transmitting insulating substrate such as a glass substrate, or it can be laminated as a coating material on ITO on a glass substrate as shown in Example 1.
TO (300-1500 people) snox (200-40
It was also effective as a two-layer structure with 0 people).

In the above embodiment, Fil? It is effective to improve the film growth rate at 3 KH (light energy) and to reduce the discharge output in the PPCVD method to further reduce spatter.

In addition, in the above description of the present invention, instead of performing Photo CVD on a small area using a carbon dioxide gas laser, etc., Photo CVD is used to form a 'IIl film on a large area 10 times or more.
It has been found that it is now possible to form a film using the CVD method and the ppcvD method.

As is clear from the above description, the present invention allows the reactive gas to flow downward from above, and the substrates are spaced vertically (vertically) at intervals (1 to
The reaction space is surrounded by a holder to prevent reactive gas from leaking outside the reaction space.

Furthermore, in order to prevent one substrate from being in the shadow of another substrate, the surface of this substrate is irradiated with light in parallel to optically excite the reactive gas while it is in flight.As a result, the embodiments of the present invention As shown in the figure, it is possible to insert 20 wafers/lot of 20 cm x 60 cm, or 100 wafers/lot as well as 5-inch silicon substrates, which is 20 times more than the maximum of 5 wafers of 5-inch wafers in the conventional method. We believe that mass production becomes possible and the industrial effects are extremely large.

[Brief explanation of the drawing]

FIG. 1 shows an outline of a conventional Photo CVD apparatus. FIG. 2 shows an outline of a Photo CVD and photo plasma CVD apparatus using the method of the present invention. FIG. 3 shows the emission characteristics of the FIR zircon lamp used in the present invention and the absorption characteristics of the 5t-H system. FIG. 4 shows electrical conductivity characteristics obtained by the method of the present invention and the conventional example. Patent Applicant Procedural Amendment (Method) November 9, 1980 Commissioner of the Japan Patent Office 1. Indication of the case 1988 Patent Application No. 134899 2. Name of the invention Optical CVD device 3. Person making the amendment Related: Patent applicant: October 1, 1982 (Delivery date: October 25, 1988) 5. Drawing subject to amendment (Figure 4) 6. Attach the content drawing of the amendment (Figure 4) as attached. . B play (hdo) Grass C sword

Claims (2)

[Claims] A light source that holds the substrate under a reduced pressure of 1.1 atm or less and irradiates the formation surface and reaction space with continuous light that emits light with a wave number of 1500 cm or less as a peak light for photochemical reaction of a reactive gas. A photo-CVD apparatus characterized in that: is arranged in a reactor. While holding the substrate under a reduced pressure of 2.1 atm or less, a reactive gas is introduced from one side and discharged from the other, and light with a wave number of 1500 cm' or less is the peak light for the photochemical reaction of the reactive gas. A light source that irradiates the formation surface and the reaction space with continuous light is disposed in the reactor, and a pair of capacitively coupled electrodes are provided for supplying electrical energy for discharge plasma to the reactive gas. An optical CVD apparatus characterized in that: 3. In claims 1 and 2, 15
A photo-CVD apparatus characterized in that a light source that generates a wave number of 00 cm' or less is made of a heated ceramic heating element, for example, a ceramic whose main component is zircon. 4. In claims 1 and 2, the reactive gas is introduced from one side along the surface on which the substrate is formed,
An optical CVD apparatus characterized in that the light is emitted to the other side and irradiates light with a wave number of 1500 cm' or less in parallel to a surface to be formed.