JPS59198718A - Manufacture of film according to chemical vapor deposition - Google Patents

Abstract

PURPOSE:To check generation of a mixed region at the interface of a film between a film forming surface, to enhance the interfacial characteristic, and moreover to make the film growing speed to be a high speed by a method wherein a first film is formed on the film forming surface according to the photo CVD method, and a second film of the same material is laminatedly formed moreover according to the PPCVD method or the PCVD method on the topside thereof. CONSTITUTION:A first film is formed according to the photo vapor phase reaction method on the film forming surface of a substrate 1, and a second film of the same material is laminated to be formed according to the photo plasma chemical vapor deposition on the film thereof. For example, reactive gas of a semiconductor consisting of silane is sent to a reaction system 10 through a flowmeter 29. Substrates 1 having film forming surfaces held at 100-500 deg.C are arranged in the reaction system thereof, and silane is fed making pressure of a reaction region 44 to be 0.1-10Torr. Thereupon irradiation of light is performed using a lamp to radiate infrared light, and silicon films are formed on the film forming surfaces. Then electric energy is applied to electrodes 5, 6 from a high-frequency oscillator 4 in addition to photo energy thereof, PPCVD reaction according to plasma glow discharge is performed, and the semiconductors of the same material are laminated continuously on the semiconductor formed by photo CVD.

Description

[Detailed Description of the Invention] This invention is based on the Photo Chemica method.
A first semiconductor layer is formed by vapor deposition (hereinafter referred to as photo CVD or photo CLr), and then plasma vapor deposition (hereinafter referred to as PCVD) or photo plasma vapor deposition (photo CLr) is applied to the second surface of the first semiconductor layer.
o Plasma Chemical VaporD
The present invention relates to a photo-CVD method in which a second semiconductor layer is stacked and formed using a method (hereinafter referred to as PPCV D), which enables mass production.

This invention uses a photo-CVD method that directly performs a photochemical reaction by supplying light energy and thermal energy to a reactive gas, without using a mercury sensitization method, to sputter (sputter) the surface to be formed. 1 coating, for example, a non-single crystal semiconductor, 5
After forming the film to a thickness of 0 Å or more, a second film of the same thickness is further laminated on the top surface using the PPCVD method or PCVD method, which has a high film growth rate.
It is characterized by preventing the generation of a mixed region at the interface with the surface on which it is formed, thereby improving the interface properties, and in addition, increasing the substantial film growth rate.

Conventionally, in the photoCVD 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 light from perpendicularly above the surface. A known method involves photoexciting a reactive gas by irradiating it with light to cause a photochemical reaction.

In this conventional method, when mercury sensitization is not used,
The film growth rate was as low as 0.1 to 0.3 people/second, and it was completely impossible to put it into practical use industrially.

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. It had the disadvantage of weakening its strength.

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

The present invention eliminates these drawbacks and proposes a photoCvD device that can be industrially mass-produced for the first time.

On the other hand, in the PCVO method or the PPCV D method, although the growth rate of the film is extremely fast at 2 to 20 per second, the surface of the surface to be formed is sputtered, and the components of the substrate constituting this surface are sputtered. This method has the disadvantage that a portion of the liquid is mixed into a film, such as a semiconductor film, as an impurity.

Both of these drawbacks have been removed, and the interface properties have been improved by photo-CVD.
A feature of the present invention is that the film growth rate has been improved by the PPCVD method.

Therefore, in the present invention, among semiconductors mainly composed of silicon, silane (SinH2yl+2 n k l
), infrared light having optical energy absorbed by 10 to 15% of Si--H bonds is optically excited using a carbon dioxide laser or a far-infrared light source using nichrome as the light source. It is also effective to perform photo-CVD using ultraviolet light of 185 nm or 254 nm.

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

FIG. 1 shows an outline of a conventionally known FO1-CVD apparatus.

In the drawing, the substrate (1) is placed inside the reaction vessel (2), and the temperature is heated from below to 200 to 400°C by a heater (53).
is heated to. Further, ultraviolet light (253 nm) is irradiated (51) by a low-pressure mercury lamp (9) in a vertical direction onto the surface of the substrate (1) through the quartz plate. Oil (54) is applied to the lower side of the quartz plate to reduce adhesion of reaction products. The reactive gas is a doping system (20)
The silane (26) is supplied to the valve (28) from the flowmeter (29).
) is supplied parallel to the substrate surface (50). Hydrogen or helium as a carrier gas is supplied from (27), a photochemical reaction takes place, and the semiconductor film is transferred to the substrate (1).
formed into l. Unnecessary reaction products and carrier gas pass through a pressure regulating valve (13) and are pumped into a vacuum pump (13).
8) Exhausted to the outside.

In such conventional equipment, the oil (54) is 200
Heating to ~400°C is prohibited because oil vapor will be mixed in. For this reason, it is considered important to heat only the substrate from the back side of the substrate. However, with this method, it is not possible to arrange a large number of substrates at once, and it has been completely impossible to put it into practical use industrially.

That is, if another board is placed at (1'), (1)
As a result, the surface of (1) was irradiated with ultraviolet light and turned into a shadow. Therefore, no photochemical reaction can occur on the lower substrate (1).

The conventional CVD method alone cannot form a large amount of a film at a high growth rate on a substrate.

Furthermore, in the conventional method shown in FIG. 1, this photochemical reaction is based on the idea that the photochemical reaction on the surface of the substrate 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 not possible to make the quartz 4 & (48) large in area in order to prevent damage due to pressure or the like.

For this reason, it has been difficult to insert only two to three 3-inch wafers as substrates at the same time.

On the other hand, the present invention is based on the experimental discovery that a photochemical reaction can be carried out even on a flying reactive gas as a result of thorough investigation of this photoCVD method. Furthermore, rather than irradiating light to form a film on the surface of the film,
Rather, they discovered that this is possible by using thermal energy.

In fact, it has been found that in the case of a silicon film, it is not necessarily necessary to irradiate the surface on which it is formed with ultraviolet light at a temperature of 250° C. or higher, for example, 300 to 350° C.

In addition, even at such temperatures, the CVD method does not use mercury, which is a source of impurities, as a sensitizing material, so the growth rate of the film is 0.1 to 0.3 people/second (
6 people/min to 18 people/min). Therefore, in the method of the present invention, PCVD or PPCVD can be performed using only light energy (light energy and thermal energy).
The first layer is applied to the surface to be formed to an average thickness of 50 to 500, so that even if the surface to be formed is spun, the substrate components will not be mixed in.
A semiconductor layer is formed on the top surface of the semiconductor layer, and while this photo-CVD is performed on the top surface, electrical energy is simultaneously supplied to the reactive gas to promote activation of the reactive gas, and as a result, the growth rate of the reactive gas film is increased by approximately 10%. It has increased to 6 to 20 people/second, which is more than double the number (
It is characterized by being able to

In the PPCV D method of the present invention, a part of the reactive gas is irradiated with light in order to facilitate the interval between discharges and to prevent instability in which the discharge is likely to stop even after it has been discharged. By exciting and adding electrical energy to the reactive gas at the same time as light energy,
The feature is that it is easy to start the discharge, and it is also easy to sustain the discharge.

The fo1-CVD apparatus of the present invention will be described below according to the drawings.

Figure 2 shows photocvD, PPcvD and PCVD (
7) An outline of a CVD apparatus that can be implemented arbitrarily is shown.

Example 1 FIG. 2 has a reaction system (10) and a doping system (2o).

The reaction system (10) has an inner volume of the reaction container (2) (width 90 cm)
A substrate (1) having a surface to be formed is held in a quartz holder (19) at a height of 60 cm and a depth of 120 cm.

This holder is 65 cm x 65 cm, but has a length of 20 cm in the direction of flow of the reactive gas (50), with a length of 2
0 cm x 60 cm (20 D substrates (formed surface) total area 24000 crl) are inserted at the same time.

Furthermore, the surface of the substrate (1) on which reactive gas is introduced is arranged in a forest at regular intervals (2 to 10 cm, for example, 5 cm) in the vertical direction along the flow of the reactive gas introduced from above and discharged downward. .

Furthermore, in the device of the present invention, a halogen heater (7
) and the space where the photochemical reaction lamp (9) is located are adjusted by opening and closing the valve (49) so that it is equal to the pressure of the reaction vessel (2), and the pressure in the space where the photochemical reaction lamp (9) is located is adjusted by opening and closing the valve (49). It is maintained at ~1 Otorr. Therefore, the quartz substrate (48) is not damaged, and the large area (80
cm x 80cm). Therefore, the reaction space is 65cm x 65cm and 20-60cm high.
) It became possible to create a large space.

The substrate is heated by a halogen heater (7), e.g.
heated to 00°C. In addition, 185nm, 253n
A photochemical reaction cup (9) emitting light with a wavelength of m or 10.6 μm is provided at the same time in the upper and lower light sources. As a result, it is possible to perform photo-CVD on a heated substrate at a predetermined temperature.

The irradiation light irradiates the entire reaction space (44). Furthermore, a pair of capacitively coupled electrodes (5) and (6) are provided in a mesh shape, and a high frequency oscillator (4013, 56M
Hz, 5-500W).

By applying electrical energy between these electrodes, PCV
It is possible to execute D.

It is also possible to perform PPCVD by applying electrical energy and optical energy simultaneously.

The reactive gas flows from the inlet (11) through the quartz nozzle (3) to the reaction space (44), and through the quartz outlet (8) to the reaction space (44).
12) Leads to the exhaust system.

The exhaust system discharges unnecessary substances to the outside through a pressure regulating valve (13), a stop valve (14), a mechanical booster pump (17), and a rotary pump (18).

The board is first placed in the preliminary chamber (16) using a quartz holder, and after being pulled through the air (23), it is placed in the gate valve (
45) was opened and moved to the reaction section (44). The reactive gas is silane from (26) in the doping system (20),
Other reactive gases for P-type such as diborane (B2H,) or gases for N-type such as phosphin (PH3) (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 respectively connected to the flow needle (2).
9) and controlled by a valve (28).

The semiconductor reactive gas consisting of silane is detected by a flowmeter (29)
The reaction system (10) is reached through the steps. This reaction system has 100~
A substrate having a surface to be formed is maintained at 500°C, preferably 250 to 350"C, typically 300"C, and the pressure in the reaction area (44) is maintained at 0.1 to 10 torr.
For example, at 2 torr, the silane flow rate is 1 to 500 cc.
For example, 50 cc was supplied for 7 minutes. light energy 1
A lamp (length 6
80 cm, diameter 10 mm, maximum output 50W x 8
) was used for light irradiation. This was also effective using a carbon dioxide laser.

In this way, a silicon film was formed on the surface to a thickness of 50 Å or more.

Next, in addition to this optical energy, electrical energy is applied from a high frequency oscillator (frequency 13.56Ml1204) to a pair of (5>, <6) to generate a plasma glow discharge to perform a PPCVD reaction. PPCV D of semiconductors of the same material continuously on semiconductors
Laminated by.

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 hidden behind the substrate and not irradiating the reactive gas on the opposite side.
PhotoCvD, which can be mass-produced, was successfully implemented. 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 the surface of the substrate is not irradiated with light (but the surface of the substrate is not sufficiently coated). It also has the advantage of being possible.

The growth rate of this semiconductor film was 0.1 to 0.3 people/second, for example 0.2 people/second, in the case of only photoCvD. In addition, in PPCVD, it was possible to obtain 30 times faster growth of 6 to 15 people/second, for example 12 people/second.

That is, in the photoCvD method, since the substrate surface was not damaged by plasma, a good film quality could be obtained. However, the growth rate of the film is 0.1 to 0.3 people/
It has the disadvantage that it is extremely slow (seconds) and the light energy required is extremely powerful.

On the other hand, the ppcvo according to the present invention shows some damage caused by plasma, but the growth rate of the film is 6 to 1.
We were able to perform growth at a rate of 5 people/sec, which is 30 times faster than the photoCvD method. In this PPCVII method, the sequence of steps is to apply thermal energy to the reactive gas and first irradiate it with light, so that a part of the reactive gas is photoexcited and becomes highly ionized, and then electrical energy is applied. It is extremely important that a plasma reaction is generated. By doing so, it was possible to prevent plasma shock waves at the start of discharge, and substantially prevent plasma damage to the substrate surface.

Furthermore, in order to prevent plasma damage that may occur even with this, in the present invention, a semiconductor film is formed in advance as a first film to a thickness of 5 OA or more on the surface to be formed using only the CVD method. Therefore, part of the substrate components constituting the formation surface will not be mixed into the semiconductor due to this plasma damage, and the interface with the formation surface will be similar to that of conventional PCV.
In method D alone, there were 100 to 300 people in the boundary area, but this could be made extremely thin to 0 to 100 people, typically 20 to 50 people.

Therefore, the surface to be formed is a P-type semiconductor (silicon or 5ixC).
1-, Q<x<l), and when an I-type silicon semiconductor is to be formed on the upper surface by the method of the present invention, this PI junction interface can be made extremely steep, resulting in good diode characteristics. I was able to get

Furthermore, when the surface to be formed is a light-transmitting conductive film, when trying to form a semiconductor on the conductive film, oxygen from ITO and SnO□, which constitute the conductive film, may be mixed into the semiconductor due to the interface. It was possible to obtain good semiconductor characteristics without any problems.

In the method of the present invention as described above, by controlling the oxygen concentration of the non-single crystal semiconductor mainly composed of silicon to 1Xl0"cm' or less, it was possible to form an even better semiconductor on the surface to be formed. .

Examining the film quality of the silicon film formed on the glass substrate by the method of the present invention, the oxygen concentration was less than IXIO18atom/cc (light output 100W
, a discharge output of 100 hl or less).

Furthermore, if the discharge output is 50W, 2 x 10" a
tom/cc=! : It was possible to further reduce it to I15. However, on the other hand, when examining the film quality of a silicon film formed on a glass substrate only by the PCVD method, the film contained 4X10' to 2X10'' atoms/cc, which is 10 to 100 times higher than that of the method of the present invention. Oxygen was mixed in. This was because some silicon from the glass substrate was spattered by glow discharge plasma and mixed into the semiconductor.

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.
At 00°C, it was also possible at i < 150-300°C.

In the 1-CVD method, when monosilane is used as the reactive gas, the reaction rate is extremely low, and industrial improvements have been sought.

It is possible to use purified monosilane instead of the above-mentioned monosilane, and synthesize low-oxygenated polysilane (for example, disilane S +, U6) by modifying this silane by a non-polar discharge method or irradiation with ultraviolet light. . When producing a semiconductor film by the above-mentioned Fo1-CVD method using a silane containing at least a portion of this disilane (concentration of 5 to 30%), the growth rate of the film is set to 0.6 people/second, and the monosilane We were able to increase it to three times the original value.

Furthermore, if the concentration of disilane is 75% or more, an additional 1
~3 people/sec.

In addition, if a semiconductor coating is formed using disilane following photoCVD using the PPCVD method, ~10
A film growth rate of 0 people/second could be obtained.

Therefore, it has been found that when disilane is used as a raw material in the method of the present invention, ultra-high-speed film growth can be performed without causing spatter on the surface on which the film is to be formed.

FIG. 3 shows a silicon semiconductor layer having a thickness of 0.5 μm formed on a glass substrate using the apparatus shown in FIG.

FIG. 3 particularly shows the method of the present invention (4) CVD method (light output 0.
1KW, 300℃) to a thickness of 100 people.
Furthermore, the PPCV D method (light output 0.1KW, (4mW
/cJ) with a discharge output of 50 W) to form a silicon semiconductor with a total film thickness of 0.5 μm.

Electrical properties of silicon semiconductors (56), (64), <65
>, (66).

(68), 0 produced only by the conventional pcvo method.
, electrical properties of a 5μ thick semiconductor (57), (63),
(58), (67).

(69) is shown.

In the drawing, in the conventional example, the region (59) shows dark electrical conductivity (57), which is 3 x 10-'(Ωcm>-'
It has a value of . Here AM l (100mW/
cJ) in the range (6θ), the conventional method has IXIP(Ωcm)-' as shown in curve (58), and the value has deteriorated by about one order of magnitude after continuous irradiation for 2 hours. Ta.

This is because oxygen flows in through the glass of the substrate and combines with some hydrogen in the reactive gas to form water (011 group), inducing photodegradation characteristics.

On the other hand, the semiconductor film produced by the present invention (7O1-CVD + PPCVD) method has a dark conductivity (56) of 1
Xl0-"(Ωcm)-', and its photoconductivity (64
) has 2×104 (Ωcm)-' (7), t-goo and photosensitivity of 106, which is about two orders of magnitude larger than that of the conventional example, and furthermore, when irradiated with continuous light, the curve (
As seen in 65), almost no deterioration of the electrical conductivity was observed. This confirmed the importance of coating a semiconductor on a glass substrate by Fo1-CVD. The average thickness of the semiconductor produced by this photo-CVD method is preferably 50 Å or more (preferably 100 to 100 Å), and if it is less than that, it may not be possible to cover a part of the area, so the effect is not necessarily sufficient.

Furthermore, in the present invention, the dark conversion conductivity after irradiation in region (61) was also the same within the range of error compared to (6G) and (56).

When heating is further performed to 150°C, the conventional example shows a curve (6
7) became (69), there was an apparent change in the above characteristics, and then when the region (62) was irradiated with light again, the deterioration characteristics were observed again.

That is, in the conventional example, the electrical conductivity is small as shown in (67), and deterioration characteristics are observed when exposed to light.

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 the photoconductivity and photosensitivity (difference between photoconductivity and dark conductivity) were 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 in that it can provide a silicon semiconductor layer having high reliability.

The method of the present invention has virtually no spackle effect and allows for mass production. As a result, PN or PIN junctions can be used in photoelectric conversion devices, optical sensors, electrostatic copying machines, etc.
The present invention can be applied to insulated gate field effect semiconductors and their integrated devices, and is considered to be extremely effective industrially.

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

The device was constructed using Figure 2.

Ultraviolet light of 185 nm and 254 nm was used as a light source for photochemical reactions.

In FIG. 2, purified silane was supplied from (26) and ammonia was supplied from (25) with NH,/SiH4>50.

As a result, in the photoCvD method, it was possible to form an insulating silicon nitride film with a thickness of 50 Å or more at a rate of 0.1 per second. By applying the PPCVD method to this silicon nitride film and applying the same electrical energy as in Example 1, three people/
The film growth rate in seconds was measured at a substrate temperature of 300°C and a pressure of 1 tor.
I was able to obtain it at r.

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 1×1 Qll Cm″2 or less in both cases.

Furthermore, even if an electric field strength of 2X10'ν/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.

9 was used instead of ammonia as the reactive gas (25
) was introduced. Furthermore, silane was added from (26) to NaO
/S 1%>20. The results obtained were similar to Example 2. Furthermore 1 xlO' V/a
It had a dielectric strength of m.

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. As a reactive gas (2
Indium chloride was added from 6), and NO was added from (25). Furthermore, in order to lower the sheet resistance of the oxide insium formed from (24), tin tetrachloride was added, and nitrogen was further added from (27) as a carrier gas.

After this, four-CVD is performed to create a first film,
Furthermore, a second film was laminated by applying electrical energy continuously and using the ppcvD method.

or indium oxide or ITO from 100 to 50
It could be obtained at 0°C, for example, 300°C.

The film formation speed is 7 people/second by PPCVD method.
It could be made at rr300°C.

Sheet resistance is 20Ω/mouth at 500 people film thickness, transmittance 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.

As reactive gases, tin chloride (24) and NO (2
5) was added as NxO/5nC1+>20.

At the same time, C%Br was added from (26) to lower the sheet resistance to 50Ω/or less (in the case of 100mm thickness).

The formed film was further fired at 500° C. in an NO atmosphere or a mixed λ atmosphere of oxygen and nitrogen while adding irradiation light for photochemical reaction.

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 the ITO on the glass substrate shown in Example 1. ．． (200~
It was also effective as a two-layer structure (400 people).

In the method of the present invention, the film formed uses T? It can also be applied to the production of metal aluminum by adding 1A (+-remethylaluminum) or 0.1 to 1% silane thereto, or to the production of other metal coatings.

As is clear from the above explanation, the present invention improves interfacial properties by forming a film on a reactive gas by the CVD method, and then performing PPCVD to form the film continuously in the same reactor. It has also been achieved. This PI
``CVD may be replaced by PCVD, or either may be repeated in the film preparation.

However, in PCVD, there is a spackle effect at the start of discharge and when discharge is unstable. For this reason, pcvo
When using the method, 7. ttoCV D -r'PCV
It is important to perform PPCV D between D-PCV I) to remove the sputtering effect at the start of discharge.

The present invention prevents one board from being in the shadow of another board.
The feature is that the surface of this substrate is irradiated with light in parallel to excite the reactive gas while it is in flight, and as a result of the trick,
As shown in the embodiments of the present invention, 7 e) CVD, P
It has become possible to carry out CVD and PPCVD in the same reactor. In addition, 20 20cm x 60cm substrates or 1 5-inch silicon substrate
00 sheets can be inserted, compared to the conventional method of 10 to 30 sheets.
High-speed coating manufacturing method makes it possible to produce double the amount.
We believe that the industrial effect is extremely large.

Of course, the device using the method of the present invention is not limited to the structure shown in FIG. 2; it is possible to make the device in a shape and size other than those described in the embodiments.

[Brief explanation of drawings]

FIG. 1 shows an overview of a conventional Fumet CvD device. Figure 4A2 shows an outline of a CVD apparatus using the method of the present invention. FIG. 3 shows electrical conductivity characteristics obtained by the method of the present invention and the conventional example. Patent Applicant/--111--□-- Myo 1 Figure 841 Cut (Muto) Midori 9 (2 Commissioner of the Patent Office Tono 1, Indication of the case 1982 Patent Application No. 072557 2, Name of the invention Coating production method by phase method 3, relationship with the case of the person making the amendment Patent applicant 4, date of amendment order July 6, 1980 (shipment date July 26, 1988) 5. Application subject to amendment and Specification 6, Contents of amendment

Claims (1)

[Scope of Claims] (i) Forming a first film on the surface to be formed on the substrate by a photovapor phase reaction method; A method for producing a film by a vapor phase method, characterized in that a second film is formed by laminating the second film. 2. Forming a first film on the surface to be formed on the substrate by a photovapor phase reaction method, and laminating a second film of the same material on the first film by a plasma vapor phase method. A method for producing a film using a vapor phase method. 3. In claim 1 or S2, the first
and a method for producing a film by a vapor phase method, characterized in that the second film contains silicon of the same conductivity type as a main component. 4. In claim 1 or 2, the first
and a method for producing a film by a vapor phase method, characterized in that the second film contains silicon nitride or silicon oxide as a main component. 5. In claim 1 or 2, the first
and a method for producing a film by a vapor phase method, characterized in that the second film is made of a light-transmitting conductive film containing tin oxide and indium oxide as main components. 5. In claim 1 or 2, the first
and a method for producing a film by a vapor phase method, wherein the second film has an average thickness of 50 Å or more.