JP2000232073A - Polycrystalline silicon film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a polycrystalline silicon film which does not contain an amorphous silicon phase so as to provide a photovaltaic element based on a polycrystalline silicon film having a high short-circuit current, and a method for efficiently manufacturing the polycrystalline silicon film. SOLUTION: A mixture gas, containing a chlorinated silane gas such as hydrogen and dichloro-silane and having an H/Cl ratio of 1 to 50 as a ratio of the number of hydrogen atoms to the number of chlorine atoms is used as a material gas, polycrystalline silicon is deposited on a substrate, such as a glass substrate through a plasma chemical vapor deposition method to form a polycrystalline silicon film which does not substantially contain amorphous silicon phase.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a photovoltaic element represented by a silicon-based thin-film solar cell, a polycrystalline silicon thin film used for the photovoltaic element, and a method for producing the same.

[0002]

2. Description of the Related Art As a silicon-based thin-film solar cell, an amorphous-silicon thin-film solar cell using amorphous silicon for a photoelectric conversion layer is widely known. It has already been put to practical use as a consumer power supply. However, an amorphous silicon thin-film solar cell generally has lower energy conversion efficiency than a crystalline silicon-based thin solar cell using a single-crystal silicon wafer or the like.
Energy conversion efficiency gradually decreases with power generation time,
Because of the so-called photo-deterioration phenomenon, further improvement in performance is required for use in high-power applications in place of fossil fuels.

In order to improve the performance and reliability of such silicon-based thin-film solar cells, attempts have recently been made to change the photoelectric conversion material from an amorphous silicon thin film to a polycrystalline silicon thin film.

[0004] The merits of making the polycrystalline silicon thin film include the following. That is, first, the photodegradation phenomenon described above is not observed in a solar cell using a polycrystalline silicon thin film for the photoelectric conversion layer, and it is considered that a highly reliable thin film solar cell can be obtained. Also, a valence-controlled polycrystalline silicon thin film obtained by adding boron, phosphorus, or the like as a dopant into polycrystalline silicon is used as a p-type semiconductor layer of a polycrystalline silicon thin film solar cell or an amorphous silicon solar cell or n. It has also been reported that the photoelectric conversion efficiency can be further improved by using it for a mold semiconductor layer. Furthermore, since the doping efficiency is higher in the crystalline structure than in the amorphous structure, the amount of the impurity element added can be reduced.

As a technique for producing a polycrystalline silicon thin film used as a material for a polycrystalline silicon thin film solar cell, a chemical vapor deposition method (CHEMICAL VAPOR DEPOSITION: hereinafter also referred to as CVD) is generally employed. Among them, a high-frequency plasma CVD method, which is a kind of plasma chemical vapor deposition (plasma CVD), is suitably used.

A specific method for manufacturing such a polycrystalline silicon thin film is disclosed in, for example, Japanese Patent Application Laid-Open No. 5-90158.
A method of manufacturing a polycrystalline silicon thin film by repeatedly supplying and stopping a silicon-based thin film forming material in an atmosphere containing charged particles obtained from a specific gas is disclosed. According to the description of JP-A-5-90158, the above method is effective when the film thickness obtained in one repetition step is 0.1 to 10 nm. Further, according to the method, a polycrystalline silicon thin film having excellent crystallinity can be obtained even if the film thickness is as thin as 30 nm or less.

Japanese Patent Application Laid-Open No. 4-137725 discloses a reaction gas comprising at least a silicon halide and a hydrogen gas, wherein the number of halogen atoms in the reaction gas is adjusted to be larger than the number of hydrogen atoms. A method of obtaining a polycrystalline silicon thin film which is crystallographically strongly oriented in the (100) direction by a plasma CVD method or a photo CVD method is described. The deposition rate of the polycrystalline silicon thin film in this method is about 0.03 nm per second.

[0008]

However, the existence of a polycrystalline silicon film obtained by the above-described method has been confirmed, for example, by a cross-sectional photograph of a transmission electron microscope (TEM). Generally, it is known that a thin amorphous silicon layer is formed near the interface with a base layer such as a base material during the growth of a polycrystalline silicon thin film.

Since the amorphous silicon layer has a high resistance,
For example, when the polycrystalline silicon thin film obtained by such a method is applied to a solar cell, the amorphous silicon layer acts as a series resistance component and degrades device characteristics. For this reason, it is preferable to make the amorphous silicon layer as thin as possible, but it is difficult to make the amorphous silicon layer thin in the above-mentioned conventional technology.

The temperature of the substrate during the formation of the polycrystalline silicon thin film should be 300 ° C. or higher, or the deposition rate should be 0.1 n
When the thickness is set to m or less per second, the thickness of the amorphous silicon layer can be reduced to some extent. However, such a condition is not preferable because it leads to a decrease in production efficiency and other physical properties. Further, even if such conditions are employed, for example, when used in a state of a very thin film having a thickness of 10 nm or less depending on the structure of an element such as a p-type semiconductor layer or an n-type semiconductor layer in a solar cell. At present, the amorphous silicon layer cannot be eliminated to a level that does not substantially affect the element performance.

An object of the present invention is to provide a polycrystalline silicon thin film having excellent crystallinity and electrical characteristics even at a film thickness of, for example, 10 nm or less.

[0012]

Means for Solving the Problems The present inventors have intensively studied to solve the above-mentioned problems. As a result, in the case of using a source gas containing chlorinated silane and hydrogen at a specific ratio in the plasma CVD method, a new amorphous phase is hardly formed in the initial stage of polycrystalline silicon deposition. The knowledge was obtained and the present invention was completed.

That is, a first aspect of the present invention is a polycrystalline silicon film formed on a base layer by a plasma enhanced chemical vapor deposition method, wherein the polycrystalline silicon film is substantially free of an amorphous silicon phase. It is a membrane.

The polycrystalline silicon film according to the first aspect of the present invention substantially has no amorphous silicon layer and therefore has a high conductivity. When a photovoltaic element is actually formed, its series resistance is reduced. Is not high, and an element having a large short-circuit current can be obtained. Further, among the polycrystalline silicon films, the polycrystalline silicon film having a hydrogen atom content of 0.01 to 5 atomic% and a chlorine content of 0.005 to 5 atomic% has a further higher crystal fraction. And the electrical properties are improved by reducing defects such as dangling bonds.

Among the polycrystalline silicon films according to the first aspect of the present invention, those exhibiting a random crystal orientation, ie, those exhibiting no preferential crystal orientation in a specific direction,
The characteristic is that there is no two-dimensional anisotropy in the characteristics.

Further, each of the above-mentioned polycrystalline silicon films is doped with a p-type group III element or a V-type group element in the periodic table (hereinafter collectively referred to as an impurity element) to form a p-type silicon film.
It can be a polycrystalline silicon film having a type semiconductor property or an n-type semiconductor property. The polycrystalline silicon film exhibits a high p-type semiconductor property or an n-type semiconductor property even when the amount of the impurity element is small, and furthermore, when the polycrystalline silicon film is adjacent to the intrinsic semiconductor layer, the impurity element diffuses into the intrinsic semiconductor layer. The characteristic is that there is little.

According to a second aspect of the present invention, there is provided a photovoltaic device comprising at least an n-type semiconductor layer, an intrinsic semiconductor layer, and a p-type semiconductor layer, wherein the intrinsic semiconductor layer contains no impurity element. The first book comprising the polycrystalline silicon film of the present invention, or having one or both of the n-type semiconductor layer and the p-type semiconductor layer, each having the corresponding type of semiconductor added with the impurity element. A photovoltaic device comprising the polycrystalline silicon film according to the invention.

In the photovoltaic element, since there is substantially no amorphous layer near the interface with the base layer in contact with the polycrystalline silicon film, it is possible to reduce the series resistance and increase the short-circuit current. It has the characteristic of exhibiting various photovoltaic element characteristics.

Further, a third invention is directed to a plasma chemical vapor deposition method, wherein the mixed gas contains at least hydrogen and a chlorinated silane gas, and a ratio of the number of hydrogen atoms to the number of chlorine atoms in the mixed gas. The method for producing a polycrystalline silicon film according to the first invention, wherein a polycrystalline silicon is deposited on a substrate by using a mixed gas having (H / Cl) of 1 to 50 as a source gas.

In the production method, crystal defects caused by dust such as powder and flakes generated in plasma can be significantly reduced. Further, the production method is not limited to the production of the polycrystalline silicon film of the first aspect of the present invention simply on a laboratory scale, but also has a high production efficiency mainly due to a high deposition rate. Therefore, it is sufficiently applicable as an industrial production method.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The polycrystalline silicon thin film of the present invention
A polycrystalline silicon film formed on a base layer by a plasma CVD method, and substantially does not contain an amorphous silicon phase.

Here, the base layer means a layer which becomes a base when the polycrystalline silicon thin film of the present invention is formed by a plasma CVD method. When the polycrystalline silicon thin film of the present invention is formed directly on a base material, the base material is the base layer. Further, for example, when the polycrystalline silicon thin film of the present invention is formed on the intrinsic semiconductor layer as in the case of forming the photovoltaic element of the present invention, the intrinsic semiconductor layer becomes a base layer.

The base layer is not particularly limited as long as it can deposit polycrystalline silicon on its surface by a plasma CVD method. Quartz glass, blue glass, single-crystal silicon, polycrystalline silicon, various metals, heat-resistant polymer ,
A transparent conductor and a substrate layer in which these materials are laminated, and an amorphous silicon film layer, a polycrystalline silicon film layer, and the like formed on these substrate layers are preferably employed.

The polycrystalline silicon thin film of the present invention has a plasma C
Although it is formed by VD, as the plasma CVD method, a conventionally known plasma CVD method capable of forming a polycrystalline silicon thin film can be adopted. Specifically, depending on the type of plasma used, a capacitively-coupled high-frequency plasma CVD method, an inductively-coupled high-frequency plasma CVD method, a microwave plasma CVD method, an ECR plasma CVD method, a helicon wave plasma CVD method, or the like can be given. .

[0025] Among these known plasma CVD methods, when CVD called so-called high electron density plasma is used, it is possible to form a polycrystalline silicon film at a high speed. High electron density plasma is generally about 10 ⁹ -1
It is defined as a plasma having an electron concentration of about 0 ¹¹ cm ^-3 . Specifically, inductively coupled plasma CVD, EC
The R plasma CVD method, the helicon wave plasma CVD method, and the like correspond. Further, among microwave plasma CVD methods, a method belonging to high-density plasma due to a difference in a microwave propagation method has been proposed. A so-called spoke antenna plasma CVD method, a surface wave plasma CVD method and the like are such.

The spoke antenna plasma CVD method is described in JA.
PANSE JOURNAL OF APPLIED
PHYSICS VOL34 1995 6805
Page and JAPANESE JOURNAL OF
APPLIED PHYSICS VOL37 199
The method is described in detail on page 1078 of the 8th year, and is a method of generating a plasma over a large area by propagating a microwave or UHF wave through a metal antenna shaped like a spoke of a bicycle. The surface wave plasma is Microwave.
Discharges, Fundamentals
and Applications, eds. C.
M. Ferreira and M.S. Moisan (P
lenum Press, New York, London
on, 1993) and JAPANESE JOUR
NAL OF APPLIED PHYSICS VO
L37, 1998, pages 170-173, which is a method of generating microwaves in a discharge tube by propagating microwaves through a waveguide called Plane Waveguide. The methods described in these documents are examples of the microwave CVD method, and various techniques may have various improvements when used.

The polycrystalline silicon film of the present invention contains substantially no amorphous silicon phase. Here, the phrase "contains substantially no amorphous silicon phase" means that, for example, when a cross section of the film is observed with a transmission electron microscope (TEM), a crystalline phase is observed from directly above the base layer, and the amorphous phase is observed. More specifically, when the Raman scattering measurement was performed on the film having a thickness of 10 nm from the base layer, the crystal component was 70%.
% Or more.

When an amorphous silicon phase as observed by a TEM exists in a polycrystalline silicon film, for example, when a photovoltaic element is formed, a series resistance component becomes large, thereby causing a short-circuit current. descend.

The polycrystalline silicon film of the present invention is allowed to contain atoms other than silicon atoms as long as the performance as a semiconductor is not impaired. Such atoms include, for example, a hydrogen atom, a chlorine atom,
Examples include an atom of a group III element or an atom of a group V element of the periodic table.

Here, the hydrogen atoms are unavoidably included in relation to the formation of the polycrystalline silicon film by using the plasma CVD method.
Preferably it is 5 atomic%. 5 atomic% hydrogen content
If it is more, an amorphous phase starts to be observed, which is not preferable. Further, in a polycrystalline silicon structure, it is generally difficult to reduce the hydrogen content in the film to less than 0.01 atomic%.

In some cases, the polycrystalline silicon film of the present invention prepared using chlorinated silane as a raw material contains chlorine atoms, and the preferable chlorine atom content at this time is 0.005 to 0.005. 5 atomic%. If the chlorine atom content exceeds 5 atomic%, when applied to a photovoltaic element, the electrical properties such as photoconductivity and dark conductivity may be reduced. When the chlorine content is less than 0.005 atomic%, an amorphous silicon phase tends to be observed in the film structure.

Further, the polycrystalline silicon film of the present invention has p
For the purpose of imparting type semiconductor properties or n-type semiconductor properties, boron,
Periodic Table II of potassium, aluminum, indium, etc.
It is also possible to add atoms of Group I elements and atoms of Group V elements of the periodic table such as phosphorus, arsenic, nitrogen and antimony. The addition amount of these impurity elements is generally represented by the concentration of the impurity element source compound gas mixed into the source gas serving as the silicon source during film formation. The amount is usually in the range of 1 to 30000 ppm, preferably 10 to 10000 ppm.

In general, a polycrystalline silicon film requires a smaller amount of impurity elements to provide p-type and n-type semiconductor properties than an amorphous silicon film. It is characterized in that the diffusion of the impurity element into another layer (eg, an underlying semiconductor layer or an intrinsic semiconductor layer laminated thereon) due to the influence of heat after the element is formed is small.
Therefore, the polycrystalline silicon film of the present invention can suppress deterioration in characteristics such as conversion efficiency when a photovoltaic element such as a solar cell is formed.

Although the crystal orientation of the polycrystalline silicon film of the present invention is not particularly limited, as far as the present inventors have confirmed so far, the polycrystalline silicon film does not show a preferential crystal orientation in a specific direction ( That is, they are randomly oriented).
Such a random orientation is preferable from the viewpoint that its characteristics have little two-dimensional anisotropy.
Here, whether or not the crystal orientation of the polycrystalline silicon film is random can be confirmed by, for example, observing diffraction peaks due to a plurality of crystal orientations by X-ray scattering measurement.

The method for producing a polycrystalline silicon film according to the present invention comprises:
Although not particularly limited, it can be suitably produced by the following method.

That is, the method for producing a polycrystalline silicon film according to the present invention is characterized in that at least hydrogen,
And the ratio of the number of hydrogen atoms to the number of chlorine atoms in the mixed gas (H /
By using a mixed gas having Cl) of 1 to 50 as a source gas and depositing polycrystalline silicon on the base layer,
It can be suitably manufactured. Hereinafter, the details of the method (hereinafter, also referred to as the production method of the present invention) will be described.

In the manufacturing method of the present invention, a chemical vapor deposition method (that is, a plasma CVD method) in which a specific source gas is decomposed by plasma to deposit polycrystalline silicon on a base layer is employed. The type of plasma used at this time is not particularly limited, and a known plasma such as a capacitively-coupled high-frequency plasma, an inductively-coupled high-frequency plasma, a microwave plasma, an ECR plasma, and a helicon wave plasma can be used. When plasma called so-called high electron density plasma is used among these known plasmas, it is possible to form a polycrystalline silicon film at a high speed. Examples of the CVD method using high electron density plasma include the aforementioned inductively coupled plasma CVD method, ECR plasma CVD method, and helicon wave plasma CVD method. Further, among CVD methods using microwave plasma, there is a method belonging to high-density plasma depending on a difference in a microwave propagation method, such as a so-called spoke antenna plasma CVD method and a surface wave plasma CVD method.

As the base layer on which the polycrystalline silicon is deposited, those described above for the polycrystalline silicon film of the present invention can be used without limitation.

In the production method of the present invention, the raw material gas is a mixed gas containing at least hydrogen and a chlorinated silane gas, and the ratio of the number of hydrogen atoms to the number of chlorine atoms in the mixed gas (H / Cl) Is used. Here, the chlorinated silane refers to a gasifiable silane compound having at least one chlorine atom in a molecule, and is preferably a compound represented by the general formula SiH _m X
_(4-m) (where m is an integer of 0 to 3 and X is a chlorine atom). Specific examples of such a silane compound include monochlorosilane (SiH ₃ Cl), dichlorosilane (SiH ₂ Cl ₂ ), trichlorosilane (SiHCl ₃ ), and tetrachlorosilane (SiCl
₄ ) and the like.

In the production method of the present invention, the chlorinated silane gas is diluted with hydrogen to obtain a raw material gas. By diluting the chlorinated silane gas with hydrogen, polycrystalline silicon can be manufactured at a low temperature, and the power output of electromagnetic waves supplied for generating plasma can be reduced.

Further, in the production method of the present invention, the ratio of the number of hydrogen atoms to the number of chlorine atoms in the above-mentioned raw material gas (hereinafter also referred to as H / Cl ratio) is in the range of 1 to 50. H
By setting the / Cl ratio in such a range, it becomes possible to deposit polycrystalline silicon on the surface of the base layer without forming an amorphous silicon phase in the initial stage of forming the polycrystalline silicon film. A polycrystalline silicon film substantially free of a crystalline silicon phase can be formed.

The H / Cl ratio in the production method of the present invention is
Although not particularly limited as long as it is within the above range, particularly preferred H
The / Cl ratio varies slightly depending on the type of plasma used. For example, when a capacitively coupled high-frequency plasma CVD method, which is a general technique for manufacturing a polycrystalline silicon film, is used, the optimal H / Cl ratio is in the range of 5 to 50. In addition, when a plasma having higher energy (electron temperature and electron density) than a capacitively coupled high-frequency plasma such as a microwave plasma or an inductively coupled plasma is used, the optimal H / Cl ratio is smaller than the above range. Well, 1-5
The range is 0. When the H / Cl ratio is in the range of 5 to 50 regardless of the type of plasma, the polycrystalline silicon film of the present invention can be obtained stably.

In the production method of the present invention, the raw material gas may be a mixture of a gasizable silane compound other than chlorinated silane as a silicon source, and argon, helium, xenon, neon, krypton, etc. It is also possible to use a mixture with a rare gas.

As the silane compound, the general formula Si _n
A silane compound represented by H _{(2n + 2)} (where n is a natural number of 1 or more) can be used. Specific examples of these silane compounds that can be suitably used include monosilane (Si
H _4), disilane (Si ₂ H _6), or the like trisilane (Si ₃ H ₈₎ can be mentioned.

When such a silane compound is used in a mixture with a chlorinated silane compound, the ratio of the chlorinated silane compound to the total silane compounds is preferably at least 50 mol%. If the amount of the chlorinated silane compound is less than 50 mol%, the structure of the obtained thin film may include an amorphous silicon phase.

When a silane (hydrogenated silane) gas containing a hydrogen atom as described above is used, or when a gas of a compound containing an impurity element described later is used, the molecule having the H / Cl ratio described above is used. The number of hydrogen atoms to be included also includes the number of hydrogen atoms in these hydrogenated silanes and impurity element-containing compounds.

In the production method of the present invention, known production conditions are not particularly limited and other production conditions are adopted as long as the polycrystalline silicon thin film is deposited as long as the above production conditions are satisfied. Generally, the plasma CVD method is widely used not only for the production of a polycrystalline silicon film but also for the production of an amorphous silicon film. Controlling. The conditions for producing a polycrystalline silicon film cannot be specified unconditionally because they differ for each type of plasma, but the conditions under which a polycrystalline silicon film can be produced for each plasma CVD method are known. In the manufacturing method of the present invention, conditions for depositing polycrystalline silicon are appropriately adopted according to the employed plasma CVD method.

As described above, the specific manufacturing conditions of the manufacturing method of the present invention may be appropriately determined according to the employed plasma CVD method, but there are general conditions common to the respective plasma CVD methods. Hereinafter, such conditions will be described.

In the manufacturing method of the present invention, the temperature of the base layer at the time of manufacturing the polycrystalline silicon thin film is not particularly limited.
The temperature is preferably from 00C to 600C, especially from 150C to 400C. If the temperature is lower than 100 ° C., the crystallinity tends to decrease during high-speed formation. If the temperature is higher than 600 ° C., the crystallinity is good, but a problem may occur in the manufacturing process of the photovoltaic device. However, even when the temperature of the base layer is lower than 100 ° C., it is possible to maintain the crystallinity by lowering the film forming rate. In the conventional method, when the base layer temperature is low, the thickness of the amorphous portion tends to increase. On the other hand, in the manufacturing method of the present invention, even when the base layer temperature is lowered to about 100 ° C., the amorphous silicon phase is substantially reduced. It is possible to manufacture a good polycrystalline silicon film without depositing the polycrystalline silicon.

As a method of heating the base layer, a known method such as a method of heating with a heater embedded in a holder for fixing the base material or a method of heating with an infrared lamp is used without any particular limitation.

The reaction pressure is also appropriately adjusted according to the type of the plasma CVD method.
The range is from mTorr to 5 Torr. Incidentally, a preferred reaction pressure in the case of using a capacitively coupled high-frequency plasma CVD method, which is a general technique for manufacturing a polycrystalline silicon film, is in the range of 30 mTorr to 5 Torr.

The power supply output for plasma generation is also appropriately adjusted according to the type of the plasma CVD method or the shape of the apparatus to be used, but a general output range is 10 W to 3 KW.
It is about. If the output of a plasma generation power source generally adopted for each type of plasma is shown, capacitively-coupled high-frequency plasma 10 W to 2 KW, inductively-coupled high-frequency plasma 10 W
~ 3KW, microwave plasma 20W ~ 2KW, ECR
The plasma is about 20 W to 2 KW.

The apparatus for producing the polycrystalline silicon film of the present invention is not particularly limited. An example of a typical device is the device shown in FIG. Inside the reaction vessel 1 of the apparatus, a high-frequency application electrode 2 and a ground electrode 3, each of which is a plate electrode, are arranged in parallel. A high frequency generator 4 is connected to the high frequency application electrode 2 so that a high frequency can be applied. Also, a base material (base layer) is set on the ground electrode 3,
The temperature of the base material can be adjusted by the heater 6 embedded in the ground electrode 3. Further, a vacuum pump 8 is connected to the reaction vessel 1 via a pressure regulator 9, so that the inside of the reaction vessel 1 can be maintained at a constant pressure.

Further, gas pipes 7a and 7b are connected to the reaction vessel 1 at positions where hydrogen and silane compound gas can be supplied via flow rate controllers 11, respectively. 1 can be introduced.

An openable and closable shutter 10 is disposed between the high-frequency application electrode 2 and the ground electrode 3. When the shutter 10 is closed during the generation of plasma, the plasma is applied to the shutter 10 and the high-frequency application electrode. This occurs only between the two, so that deposition of the polycrystalline silicon thin film on the base material 5 does not occur.

In the case of producing the polycrystalline silicon thin film of the present invention using the above-mentioned apparatus, first, the flow rate of hydrogen and the chlorinated silane compound as the raw material are controlled by the flow rate regulator 11 and then the gas pipe 7a. , 7b to the reaction vessel 1 and apply a high frequency to the high-frequency application electrode 2 to convert the gas introduced into the reaction vessel 1 into plasma between the electrodes. The plasma gas is brought into contact with the base material (base layer) disposed on the ground electrode 3 heated to a certain temperature by the heater 6, so that polycrystalline silicon is deposited on the base material 5.

Note that p-type semiconductor (or n-type semiconductor)
In order to produce the polycrystalline silicon thin film of the present invention having the following formula, a compound containing an element of Group III of the periodic table (or a compound containing an element of Group V of the periodic table) is mixed with the above-mentioned raw material gas. What is necessary is just to deposit a crystalline silicon thin film. And then the compound or the periodic table compounds containing Group V elements including the periodic table Group III _{element, B 2 H 6, BF 3} , AsH 3, AsF 5, PH 3, PF
₅ , BCl _{3 and the} like are preferably used.

The compounds containing these impurity elements are supplied in the gaseous state into the reaction vessel through a gas pipe (not shown) after the flow rate is controlled by a flow controller (not shown) in the same manner as the raw material gas. In this case, the concentration of the compound gas containing the impurity element mixed in the source gas is usually 1 to 30,000 pp
m, preferably in the range of 10 to 10000 ppm.

Since the polycrystalline silicon film of the present invention does not substantially contain an amorphous silicon phase in the film, it can be suitably used for a photovoltaic element represented by a silicon-based thin-film solar cell. For example, in a photovoltaic element including at least an n-type semiconductor layer, an intrinsic semiconductor layer, and a p-type semiconductor layer, the first semiconductor element in which the intrinsic semiconductor layer does not contain an impurity element.
The polycrystalline silicon film of the present invention, or one or both of the n-type semiconductor layer and the p-type semiconductor layer having a semiconductor property of a corresponding type to which the impurity element is added. By using the polycrystalline silicon film of the present invention, a photovoltaic element having low series resistance and excellent photovoltaic element characteristics can be obtained.

Hereinafter, the photovoltaic element (also referred to as the photovoltaic element of the present invention) to which the polycrystalline silicon film of the present invention is applied will be described.

The photovoltaic device of the present invention is provided as long as at least one of the n-type semiconductor layer, the intrinsic semiconductor layer and the p-type semiconductor layer constituting the photovoltaic device is made of the polycrystalline silicon film of the present invention. There is no particular limitation. For example, a so-called pin-type photovoltaic device having a structure in which a transparent conductive film, a p-type semiconductor layer, an intrinsic semiconductor layer, an n-type semiconductor layer, and a collecting electrode are stacked in this order on a glass substrate. It may be a power element, or a metal layer 320, a transparent conductive layer 330, an n-type semiconductor layer 34 on a substrate as shown in FIG.
1, intrinsic semiconductor layer 342, p-type semiconductor layer 343 (341)
343 form a semiconductor layer 340), a transparent conductive film layer 350, and a current collecting electrode 360, which are so-called nip-type photovoltaic elements 300 having a structure in which they are stacked in this order. You may.

The substrate in the pin type photovoltaic element is not particularly limited as long as it is a substrate having optical transparency, and a glass plate having a thickness of about 0.3 mm to 5 mm is usually used. .

The transparent conductive film layer is made of SnO ₂ , In ₂
The layer is made of an oxide such as O ₃ (Sn), ZnO, CdSnO ₄ , and TiO _2.
The thickness is as described above.

The p-type semiconductor layer has a thickness of 5 to 50 n.
m, containing an element of Group III of the periodic table such as boron or gallium, and having an activation energy of 0.5 eV or less. The intrinsic semiconductor layer has a thickness of 100 to
The n-type semiconductor layer is a layer made of silicon having a thickness of about 5000 nm and has a thickness of about 5 to 50 nm, contains an element of Group V of the periodic table such as phosphorus or arsenic, and has an activation energy of 0.3 eV.
It is a layer made of the following silicon.

The collecting electrode is an electrode formed by depositing a metal such as silver in a lattice form when provided on the light incident side, and formed by depositing the entire surface when provided as a back electrode. Electrode.

In the pin type photovoltaic element, between the transparent conductive film layer and the p-type semiconductor layer, or between the transparent conductive layer and the p-type semiconductor layer.
A buffer layer made of silicon having a thickness of 1 to 50 nm may be provided between the type semiconductor layer and the intrinsic semiconductor layer for the purpose of protecting the surface of the transparent conductive film layer and the surface of the p-type semiconductor layer from plasma.

As the substrate in the nip type photovoltaic element, those described as the substrate layer of the polycrystalline silicon film of the present invention can be used without limitation. The transparent conductive film layer and various semiconductor layers are the same as those of the pin type photovoltaic element. The metal layer is a layer made of, for example, silver, aluminum, or an alloy thereof, and having a light reflectance of 80% or more.
Its thickness is usually about 100 to 1000 nm. In the nip type photovoltaic element, a buffer layer made of silicon having a thickness of about 1 to 50 nm is provided between the n-type semiconductor layer and the intrinsic semiconductor layer to protect the n-type semiconductor layer. It may be provided. Further, in order to improve the open-circuit voltage and short-circuit current of the photovoltaic element, the transparent conductive film layer and the semiconductor layer (n
Between at least one of two locations between the semiconductor layer and the p-type semiconductor layer) and a base metal having a melting point of 1000 ° C. or higher, such as Ni, Cr, or an alloy thereof.
It is also a preferable embodiment to provide a base metal layer having a thickness of about nm.

The photovoltaic device of the present invention has a semiconductor layer ｛, that is, an n (or p) type semiconductor layer, an intrinsic semiconductor layer,
And p (or n) -type semiconductor layers are laminated, except that the layer desired to be composed of the polycrystalline silicon film of the present invention is manufactured by the manufacturing method of the present invention. Can be used without any particular limitation.

For example, when manufacturing a pin type photovoltaic element in which all of the semiconductor layers are the polycrystalline silicon thin film of the present invention, first, a sputtering method using a target such as ZnO on a glass substrate is used. A transparent conductive film is formed by, for example, a polycrystalline silicon thin film to be a p-type semiconductor layer on the transparent conductive film, and then the polycrystalline silicon to be an intrinsic semiconductor layer with the obtained p-type semiconductor layer as a base layer. After forming the film, a polycrystalline silicon thin film to be an n-type semiconductor layer is formed using the obtained intrinsic semiconductor layer as a base layer, and a metal such as silver is formed on the finally obtained n-type semiconductor layer by a resistance heating method or the like. It can be manufactured by attaching a current collecting electrode.

At this time, it is preferable to perform a heat treatment at a temperature equal to or higher than the formation temperature of the p-type semiconductor layer after forming the p-type semiconductor layer and before forming the intrinsic semiconductor layer. By performing such a heat treatment, the heat resistance and the plasma resistance of the formed p-type semiconductor layer can be improved, and then the intrinsic semiconductor layer can be formed. Diffusion into the semiconductor layer can be prevented. As a result, without forming an inactive layer at the interface between the p-type semiconductor layer and the intrinsic semiconductor layer, it is possible to form an intrinsic semiconductor layer having stable carrier transport ability even when irradiated with light, A photovoltaic element with good performance can be obtained.

The temperature of the above heat treatment is preferably 200 to 600 ° C. from the viewpoint of the effect. Further, the heat treatment is also effective when forming an intrinsic semiconductor layer on the n-type semiconductor layer (that is, when manufacturing an nip type photovoltaic element, after the n-type semiconductor layer is formed, The same effect can be obtained even if heat treatment is performed before forming the semiconductor layer.)

As described above, a general advantage of forming each semiconductor layer as a polycrystalline silicon film is as follows.
1) When the intrinsic semiconductor layer is a polycrystalline silicon film,
The advantage is that a highly reliable photovoltaic element with less photodegradation can be obtained. 2) When the n-type semiconductor layer or the p-type semiconductor layer is a polycrystalline silicon film, the efficiency of addition of impurity elements is high, and An advantage is that diffusion of elements into the intrinsic semiconductor layer can be suppressed. However, an amorphous silicon film can be formed at a high speed by selecting a source gas or the like, whereas a high-speed film formation of a polycrystalline silicon film is generally difficult. When a polycrystalline silicon film is used as an intrinsic semiconductor layer that requires the above, it may take time to manufacture a photovoltaic element.

Therefore, in the photovoltaic device of the present invention,
Which of the three types of semiconductor layers is to be the polycrystalline silicon film of the present invention may be appropriately determined from the viewpoint of performance and productivity in consideration of the above points.

Hereinafter, referring to FIG. 2, an nip type photovoltaic element in which all of the n-type semiconductor layer, the intrinsic semiconductor layer and the p-type semiconductor layer are made of the polycrystalline silicon film of the present invention will be manufactured. The method will be described specifically.

A plasma CVD apparatus 200 shown in FIG.
Mainly include a vacuum pump (mechanical booster pump 231 and a turbomolecular pump 232) communicating with each reaction vessel (211 to 213) and the sample introduction chamber 210, each reaction vessel and the sample introduction chamber, and a plasma generation source (high frequency) communicating with each reaction vessel. Generator 241) and a gas supply device 250 communicating with each reaction vessel.

In each of the above-described reaction vessels, the type of gas to be introduced is set in advance according to the type of film to be formed. Specifically, a reaction vessel 213 for forming an intrinsic semiconductor layer
A gas of a silane compound such as chlorinated silane or monosilane, which is a raw material of a silicon thin film, and a diluting gas such as hydrogen or helium can be introduced into the gas. In addition to the above-mentioned gases, a gas containing a Group III element compound of the periodic table is placed in the reaction vessel 212 for forming the p-type semiconductor layer.
1, a gas containing a Group V element compound of the periodic table can be introduced from a gas supply device.

A gate valve 270 is provided between each reaction vessel and the sample introduction chamber, and the sample (photovoltaic element in the manufacturing process) can be transferred using the transfer rod 260 without opening the vacuum system to the atmosphere. It can be moved. In addition, if a sputtering apparatus or a vapor deposition apparatus is connected to the apparatus shown in FIG.
A metal film layer, a transparent conductive film layer, and the like can also be manufactured without opening a vacuum system to the atmosphere.

In manufacturing the nip type photovoltaic element, first, a metal layer and a transparent conductive film layer are sequentially formed on a base material. The method of manufacturing each of these layers is not particularly different from the method of manufacturing a conventional photovoltaic element, and is appropriately selected from known methods such as a sputtering method, an electron beam evaporation method, a resistance heating evaporation method, and a CVD method. Just do it. The manufacturing conditions are not particularly different from the conventional method.

For example, when a metal layer is formed by a sputtering method, a metal of the same kind as the metal constituting the metal layer is used as a target at a pressure of 1 to 100 mTorr.
What is necessary is just to perform it on conditions, such as an argon flow rate of 1-100 sccm. Further, the transparent conductive film layer 330 is formed by a sputtering method.
In this case, a metal oxide having the same composition as that constituting the transparent conductive film layer may be used, and argon sputtering may be performed under substantially the same conditions as those described above. In addition,
The thickness of each layer can be adjusted by previously examining the relationship between the sputtering time and the film thickness under certain conditions and controlling the sputtering time. If necessary, a film thickness monitoring device including a quartz oscillator may be used.

Further, a texture structure can be introduced into the transparent conductive film layer or the transparent conductive film layer and the metal layer by appropriately performing etching or the like.

Next, the laminate prepared as described above was set as a base layer in the sample introduction chamber of the plasma CVD apparatus shown in FIG. 2 and evacuated to about 1 × 10 ⁻⁴ Torr. To n under the conditions described above.
After forming the type semiconductor layer, it is transferred to a reaction vessel 213 to form an intrinsic semiconductor layer as described above, and then the reaction vessel 212
Then, a p-type semiconductor layer is formed under the conditions described above. After forming the p-type semiconductor layer, the nip-type photovoltaic element can be manufactured by taking out from the plasma CVD apparatus and attaching the transparent conductive film layer and the current collecting electrode.

In the photovoltaic device of the present invention,
As long as at least one of the n-type semiconductor layer, the intrinsic semiconductor layer, and the p-type semiconductor layer is made of the polycrystalline silicon film of the present invention, the other semiconductor layers are made of a polycrystalline silicon film other than the polycrystalline silicon film of the present invention. It may be made of an amorphous silicon film. In this case, in the method for manufacturing the nip type photovoltaic device, the condition for forming the semiconductor layer is changed to a conventionally known polycrystalline silicon film or What is necessary is just to change suitably the formation conditions of an amorphous silicon film.

[0083]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

In each of the following examples and comparative examples, a polycrystalline silicon thin film and a photovoltaic element were manufactured using the apparatus shown in FIGS. 1 and 2, respectively.

The evaluation of the polycrystalline silicon thin film and the photovoltaic element obtained in the following Examples and Comparative Examples was as follows.
It carried out by the method shown to following (1)-(5).

(1) Confirmation of Amorphous Silicon Phase in Polycrystalline Silicon Film A section of the silicon film deposited on quartz glass was observed using a transmission electron microscope (TEM). In this measurement, the polycrystalline silicon phase and the amorphous silicon phase can be distinguished in the film thickness direction by the difference in contrast.

(2) Crystallinity of Polycrystalline Silicon Film The crystallinity of the silicon film was evaluated by laser Raman spectroscopy. Smooth peaks due to amorphous silicon structure wavenumber 480 cm ^-1 in the measurement, also the 520 cm ^-1 are observed sharp peaks due to the crystalline silicon structure. The crystal fraction was evaluated from the ratio of both areas.

(3) Orientation of Polycrystalline Silicon Film The orientation of the silicon film was evaluated by X-ray diffraction measurement. In this measurement, a diffraction peak due to a difference in crystal orientation is observed.

(4) Photovoltaic Element Characteristics Current voltage measurement was performed using a voltage source and a micro ammeter, and a short circuit current was obtained from a current voltage curve. Measurement is 100mW / c
The test was performed under irradiation of white light of m ² and in a dark state. The short-circuit current density was obtained by dividing the current measured without applying a voltage under light irradiation by the effective solar cell area.
The unit is A / cm ² .

Example 1 A glass substrate (5 cm × 5 cm × 0.5 cm) serving as a base material
t) is set on the sample stage of the sample introduction chamber, and the sample introduction chamber is set to about 1
Vacuum was applied to × 10 ⁻⁴ Torr. After evacuating the sample introduction chamber, the gate valve was opened, and the sample stage was guided to the sample holder in the reaction vessel 213 which was previously evacuated to the same degree as the sample introduction chamber, and the gate valve was closed. Thereafter, the surface of the sample was heated to 250 ° C. by energizing a heater embedded in the sample holder.

Dichlorosilane gas and hydrogen gas at a flow rate of 5 sccm and 50 sccm (H / Cl ratio = 11) were supplied to the reaction vessel by controlling the flow rate using a mass flow controller, and the pressure inside the reaction vessel was reduced to 5 by a pressure controller.
It was set to 0 mTorr. In this state, a high frequency was supplied from the high frequency generator to the high frequency application electrode at an output of 50 W to generate plasma. In about 40 seconds, a polycrystalline silicon film of about 10 nm according to the present invention was obtained.

The obtained polycrystalline silicon film was returned to the sample introduction chamber in the reverse procedure of introducing the base material into the reaction vessel, and nitrogen was introduced into the sample introduction chamber and taken out to the atmosphere. When a sample obtained according to the present invention was subjected to Raman scattering measurement, a peak derived from the crystal structure was observed despite a film thickness of about 10 nm. As a result of analysis by the waveform separation method, it was confirmed that the crystal fraction was 75%. Also. When the chlorine and hydrogen concentrations in the film were measured, each was 1 atomic%.
And 0.5 atomic%.

Similarly, a polycrystalline silicon film having a thickness of 300 nm was formed and its crystal orientation was measured by an X-ray diffraction method. As a result, peaks derived from the (111) and (220) directions were observed. .

Comparative Example 1 A polycrystalline silicon film was deposited under the same conditions except that the dichlorosilane gas used in Example 1 was changed to a monosilane gas.

When the sample obtained in this comparative example was subjected to Raman scattering measurement, it was found to have a film thickness of about 10 nm. However, the structure contained a large amount of amorphous material. The crystal fraction was 50% or less. The hydrogen concentration in the film was measured and found to be 5%.

Comparative Example 2 A polycrystalline silicon thin film was deposited to a thickness of 10 nm on quartz glass using manufacturing conditions according to the method of manufacturing a silicon thin film described in the example of JP-A-4-137725. .

When the obtained film was subjected to laser Raman spectroscopy, an amorphous silicon phase was observed. The crystal fraction was estimated to be 40% by waveform separation. It seems that the thickness was small, but no peak was observed from the X-ray diffraction measurement. When the thickness was 300 nm as in Example 1, a strong peak due to diffraction in the (100) direction was observed.

From the results of Example 1, Comparative Example 1 and Comparative Example 2, the formation of an amorphous silicon phase is unavoidable in a polycrystalline silicon film having a thickness of about 10 nm formed by a conventional manufacturing method. When manufactured by the manufacturing method of the present invention, TEM
No amorphous silicon phase was observed in the observation, and a polycrystalline silicon film having a crystal fraction of 70% or more was obtained in the Raman scattering measurement.

Example 2 A glass substrate (5 cm × 5 cm × 0.5 cmt) on which silver (thickness 800 nm) and zinc oxide (thickness 1000 nm) were sequentially formed in advance by a sputtering method as a base material was set on a sample table in a sample introduction chamber, and sample was introduced. The chamber was evacuated. After the sample introduction chamber was evacuated, the gate valve was opened, the sample stage was introduced to the sample holder in the reaction vessel 211 which was previously evacuated to the same degree as the sample introduction chamber, and the gate valve was closed. Thereafter, the sample surface temperature is set to 250 ° C. by energizing a heater embedded in the sample holder.
To a thickness of 2 by capacitively coupled plasma CVD.
A 0 nm n-type polycrystalline silicon semiconductor layer was formed. The conditions at this time were as follows: dichlorosilane flow rate 5 sccm, hydrogen flow rate 50 sccm, phosphine 1 vol. % Hydrogen gas flow rate 5 sccm (H / Cl ratio = 12), reaction pressure 50 m
Torr, high frequency power 50 W, reaction time 80 seconds.

After the formation of the n-type polycrystalline silicon semiconductor layer, the sample was transferred to the reaction vessel 213 under vacuum, and a 3000 nm thick polycrystalline silicon intrinsic semiconductor layer was formed by a capacitively coupled plasma CVD method. The reaction conditions at this time were as follows: dichlorosilane flow rate 10 sccm, monosilane flow rate 1 sccm, hydrogen flow rate 50 sccm (H / Cl ratio = 6.2), reaction pressure 2
00mTorr, high frequency power 200W, substrate temperature 250
C. and a reaction time of 20 minutes.

Next, after the formation of the polycrystalline silicon intrinsic semiconductor, the sample was transferred to the reaction vessel 212 under vacuum, and a polycrystalline silicon p-type semiconductor layer having a thickness of 20 nm was formed by the capacitively coupled plasma CVD method. The reaction conditions at this time were as follows: dichlorosilane flow rate 5 sccm, hydrogen flow rate 50 sccm, diborane 1 vol. % Hydrogen gas containing 3 sccm (H /
Cl ratio = 11.6), reaction pressure 50 mTorr, high frequency power 50 W, substrate temperature 250 ° C., and reaction time 40 seconds.

After the p-type polycrystalline silicon semiconductor layer was formed, the sample was transferred to the sample introduction chamber 210, the sample was taken out of the apparatus into the atmosphere, and a 70 nm-thick indium tin oxide transparent electrode was deposited by sputtering. did.

A current collecting electrode made of silver was attached to the photovoltaic device thus obtained by resistance heating evaporation, and then the current and voltage were measured. When the short-circuit current was determined from the obtained current-voltage curve, it was 25 mA / cm ² .

Comparative Example 3 In Example 2, the n-type semiconductor layer, the intrinsic semiconductor layer, and the p-type semiconductor layer
Example 2 except that the film forming conditions of the semiconductor layer were changed to the following film forming conditions for forming a conventional polycrystalline silicon film.
A photovoltaic element was produced in exactly the same manner as in Example 1. That is,
The n-type semiconductor layer is formed under the conditions of a monosilane flow rate of 5 sccm, a hydrogen flow rate of 100 sccm, a phosphine flow rate of 5 sccm, a reaction pressure of 50 mTorr, a high-frequency power of 10 W, and a reaction time of 12 minutes.
ccm, hydrogen flow rate 100 sccm, reaction pressure 50 mTorr
r, high-frequency power 10 W, and reaction time 40 hours.

The p-type semiconductor layer has a monosilane flow rate of 5 s.
ccm, hydrogen flow rate 100 sccm, diborane (1 vol
l. % As diluted with hydrogen gas) flow rate 5 scc
m, a reaction pressure of 50 mTorr, a high frequency power of 10 W, and a reaction time of 15 minutes.

The short-circuit current of the obtained photovoltaic element was determined in the same manner as in Example 2. The short-circuit current was 17 mA /
cm ² .

Example 3 In Example 2, the polycrystalline silicon film serving as the p-type semiconductor layer was formed under the conditions of a monosilane flow rate of 5 sccm and a hydrogen flow rate of 1
00 sccm, diborane (as diluted to 1 vol.% With hydrogen gas) flow rate 5 sccm, reaction pressure 50 mT
A photovoltaic element was produced in exactly the same manner as in Example 2, except that the reaction time was 10 W orr and the high-frequency power was 10 W.

The short-circuit current of the obtained photovoltaic element was determined in the same manner as in Example 2, and the short-circuit current was 20 mA /
cm ² .

Comparative Example 4 A photovoltaic device was produced in the same manner as in Comparative Example 3, except that both the n-type semiconductor layer and the p-type semiconductor layer were made of amorphous silicon films. In this case, n
The condition for forming the semiconductor layer is that the monosilane flow rate is 5 scc.
m, phosphine flow rate 5 sccm, reaction pressure 50 mTo
rr, high frequency power 10 W, reaction time 5 minutes, and p
The fabrication conditions of the type semiconductor layer are as follows: monosilane flow rate 5 sccm, diborane (as diluted to 1 vol.% With hydrogen gas) flow rate 5 sccm, reaction pressure 50 mTorr, high-frequency power 10 W, reaction time 4 minutes.

The short-circuit current of the obtained photovoltaic element was determined in the same manner as in Example 2, and the short-circuit current was 12 mA /
cm ² .

From the comparison between Examples 2 and 3 and Comparative Examples 3 and 4, at least one of the n-type semiconductor layer, the intrinsic semiconductor layer and the p-type semiconductor layer is formed of the polycrystalline silicon film of the present invention. The photovoltaic device of the present invention has a photovoltaic device in which all semiconductor layers are formed of a conventional polycrystalline silicon film (Comparative Example 3), and an n-type semiconductor layer and a p-type semiconductor layer are formed of an amorphous silicon film. The short-circuit current is higher than that of the photovoltaic element in which the intrinsic semiconductor layer is made of a conventional polycrystalline silicon film (Comparative Example 4).

[0112]

According to the manufacturing method of the present invention, for example, 10
A polycrystalline silicon film in which an amorphous silicon phase is not observed even with a very thin film thickness of nm can be efficiently manufactured.

The polycrystalline silicon film of the present invention, which does not substantially contain an amorphous silicon phase, has a low series resistance when used as a semiconductor layer of a photovoltaic element. It is possible to provide an excellent photovoltaic element having a high short-circuit current.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a typical apparatus for manufacturing a polycrystalline silicon film of the present invention.

FIG. 2 is a conceptual diagram of a typical apparatus for manufacturing a photovoltaic device of the present invention.

FIG. 3 is a conceptual diagram showing a typical embodiment of the photovoltaic device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Reaction container 2 ... High frequency application electrode 3 ... Ground electrode 4 ... High frequency generator 5 ... Base material 6 ... Heater 7 ... Gas Supply port 8 Vacuum pump 9 Pressure regulator 10 Shutter 11 Flow regulator 200 Plasma CVD device 211 Reaction container 212 for forming n-type semiconductor layer 212 P Reaction vessel for forming a semiconductor layer 213 ··· reaction vessel for forming an intrinsic semiconductor layer 231 ··· mechanical booster pump 232 · · · turbomolecular pump 241 · · · high frequency generator 250 · · gas supply device 260 · · · transfer rod 270 · · · gate Valve 300 photovoltaic element 320 metal layer 330 transparent conductive layer 340 semiconductor layer 341 n-type semiconductor layer 342 intrinsic semiconductor layer 34 · P-type semiconductor layer 350 ... transparent conductive film layer 360 .. collector electrode

Claims (6)

[Claims] 1. A polycrystalline silicon film formed on a base layer by a plasma enhanced chemical vapor deposition method, wherein the polycrystalline silicon film does not substantially contain an amorphous silicon phase. 2. A hydrogen atom content of 0.01 to 5 atomic%.
2. The polycrystalline silicon film according to claim 1, wherein the chlorine content is 0.005 to 5 atomic%. 3. The polycrystalline silicon film according to claim 1, wherein the crystal orientation is a random orientation. 4. Group III element of the periodic table or V of the periodic table
4. The polycrystalline silicon film according to claim 1, having a p-type semiconductor property or an n-type semiconductor property, to which a group element is added. 5. The photovoltaic device comprising at least an n-type semiconductor layer, an intrinsic semiconductor layer, and a p-type semiconductor layer, wherein the intrinsic semiconductor layer is any one of the polycrystalline semiconductors according to claim 1. 5. A semiconductor device comprising: a silicon film; or one or both of an n-type semiconductor layer and a p-type semiconductor layer.
A photovoltaic element comprising a polycrystalline silicon film having a semiconductor property of a corresponding type described in (1). 6. A plasma-enhanced chemical vapor deposition method comprising a mixed gas containing at least hydrogen and a chlorinated silane gas, wherein the ratio of the number of hydrogen atoms to the number of chlorine atoms (H / Cl) in the mixed gas is 1 2. The method for producing a polycrystalline silicon film according to claim 1, wherein a mixed gas of 50 to 50 is used as a source gas to deposit polycrystalline silicon on the base layer.