JP2001036113A - Photovoltaic element, manufacture thereof, and manufacturing apparatus thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photovoltaic element, having a large-area, high-efficiency and low in deterioration tandem structure, a manufacturing method and a manufacturing apparatus for the same, by eliminating nonconformities which are encountered, when a VHF plasma CVD method capable of high-speed deposition is applied to i-type layers. SOLUTION: This method of manufacturing a photovoltaic element, having a tandem structure consisting of a silicon non-single-crystal semiconductor formed on a substrate 101 by causing the substrate 101 to pass through a plurality of film forming chambers 103, 104, 105, 106, 107 and 108. Among i-type layers, a plurality of i-type layers are deposited by a plasma CVD method using VHF power. Furthermore, in the chambers 104 and 107 for these plural i-type layers, DC voltages 119 which are positively oriented with respect to the substrate 101 are applied, and lower voltage 119 is applied to a chamber the later it is in the lamination order of a higher layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photovoltaic device having a tandem structure comprising a silicon-based non-single-crystal semiconductor on a substrate, a method of manufacturing the same, and an apparatus for manufacturing the same, such as amorphous silicon, amorphous silicon germanium, and amorphous silicon. The present invention relates to a photovoltaic element such as a tandem solar cell made of silicon carbide, microcrystalline silicon, or the like, a method for manufacturing the same, and a device for manufacturing the same.

[0002]

2. Description of the Related Art Amorphous silicon is a plasma CV.
A large-area semiconductor film can be formed by the D method,
A semiconductor device having a large area can be formed relatively easily as compared with crystalline silicon or polycrystalline silicon. Therefore, amorphous silicon films are widely used for semiconductor devices requiring a large area, specifically, solar cells, photosensitive drums of copying machines, image sensors of facsimile machines, thin film transistors for liquid crystal displays, and the like.

[0003] These devices have a large area of one device as compared with devices made of crystal semiconductors such as LSIs and CCDs. For example, in the case of a solar cell, if the photoelectric conversion efficiency is 10%, the power for ordinary households is used. In order to obtain an output of about 3 kW, which covers about 3 kW, an area of about 30 square meters per home is required, and one photovoltaic element has a considerably large area.

[0004] To form an amorphous silicon film,
In general, a source gas containing Si, such as SiH ₄ or Si ₂ H _6, is decomposed by high-frequency discharge into a plasma state, and plasma CVD is performed to form a film on a substrate placed in the plasma.
Method is used.

Conventionally, when an amorphous silicon film is formed by a plasma CVD method, an RF frequency (13.5) is used.
High frequency (around 6 MHz) has been generally used.

However, in recent years, attention has been paid to plasma CVD using a VHF frequency. For example, Amorpho
us Silicon Technology 199
2p15-p26 (Materials Research
ch Society Symposium Proc
In Eedings Volume 258), it is reported that by changing the discharge frequency from the RF of 13.56 MHz to the VHF frequency, the film formation rate can be remarkably increased, and a good deposited film can be formed at a high speed.

US Pat. No. 4,406,765 discloses a high-frequency plasma CVD method in which a DC electric field is applied. By applying an appropriate DC electric field together with an electric field by a high frequency in the plasma CVD method,
It is said that a high-quality amorphous semiconductor can be obtained. In this case, the appropriate value of the applied DC voltage varies depending on the type of the deposited film, discharge conditions, and the like.

[0008] Conventionally, US Pat. No. 4,400,400 discloses a continuous manufacturing apparatus for amorphous silicon-based semiconductor devices.
Roll-to-roll (Roll-
A continuous plasma CVD apparatus employing a to-roll method has been disclosed.

According to this apparatus, a plurality of glow discharge chambers are provided, and each glow discharge chamber is arranged along a path through which a strip-shaped substrate having a desired width is sequentially passed. By continuously transporting the substrate in its longitudinal direction while depositing and forming a conductive semiconductor film to be formed, a large-area device having a semiconductor junction can be continuously formed. In this way, roll-to-
If a roll-type continuous plasma CVD apparatus is used, devices can be manufactured continuously for a long time without stopping the manufacturing apparatus, so that high productivity can be obtained.

[0010]

However, this roll
When an attempt is made to introduce a film forming method at a VHF frequency into a two-roll type plasma CVD apparatus, a light in a wider wavelength range can be used, and a high photoelectric conversion efficiency can be obtained, especially when compared with a single structure. Since the film thickness of the layer can be reduced, the following problem arises when an attempt is made to introduce a film forming method at a VHF frequency into an i-type layer of a tandem-structure photovoltaic element with less photodeterioration.

First, when applying the plasma CVD method of the VHF frequency to a roll-to-roll type apparatus for forming a deposited film over a large area, a general method is used at an RF frequency to generate a uniform discharge over a large area. When a large-area flat-plate discharge electrode is used, there is a problem that the impedance does not match at the VHF frequency and uniform plasma over a large area cannot be obtained.

If a rod-shaped radial antenna is used, the impedance is matched, but the area ratio between the discharge electrode and the counter electrode, which was substantially 1 in a parallel plate, becomes extremely small on the discharge electrode side, and the area balance is broken. On the other hand, in the case of a parallel plate having a small area, the absolute value of the self-bias of the discharge electrode, which should become smaller as the frequency increases, becomes larger, and a positive undesirable DC electric field is formed on the substrate side. Therefore, VHF
When applying the plasma CVD method of a frequency to a roll-to-roll type apparatus for forming a deposited film over a large area, a favorable film is obtained over a large area by eliminating the influence of a positive self-bias on the substrate side. It was necessary to control the DC electric field by applying a DC voltage or the like.

However, in a tandem-structure photovoltaic element, when a plasma CVD method of such a VHF frequency is applied to an i-type layer requiring a relatively large film thickness for performing photoelectric conversion, good quality is obtained. As described above, it is necessary to apply a DC voltage to obtain a proper film.However, if a high DC voltage is applied to the inside of the film formation chamber, abnormal discharge such as sparks occurs in the inside of the film formation chamber from the DC voltage application electrode, or deposition occurs. There has been a problem that the photovoltaic element to be manufactured is liable to cause a characteristic failure, for example, due to charge-up of the film surface and dielectric breakdown of the semiconductor film being manufactured.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to enable high-speed deposition when manufacturing a tandem-structure photovoltaic element by a roll-to-roll method capable of continuously forming a deposited film over a large area. VHF frequency plasma CVD
It is an object of the present invention to provide a photovoltaic element having a large area, a high efficiency and a low degradation tandem structure, a method for manufacturing the same, and an apparatus for manufacturing the same, by solving the problem when the method is applied to an i-type layer.

[0015]

In order to achieve the above object,
The method for manufacturing a photovoltaic element according to the present invention is directed to a method for manufacturing a photovoltaic element in which a substrate is passed through a plurality of film forming chambers and a tandem-structure photovoltaic element made of a silicon-based non-single-crystal semiconductor is formed on the substrate. In the method, the i-type layer of the photovoltaic element having the tandem structure does not introduce a gas containing Group III and / or Group V atoms described in <Plasma CVD method> described below, or has a Fermi level. Is formed under the condition that a small amount of Group III and / or Group V atoms is introduced so as to be located near the center of the band gap. Among the i-type layers, a plurality of i-type layers are deposited by a plasma CVD method using a high frequency power of a VHF frequency, and a plurality of i-type layers are deposited by a plasma CVD method using a high frequency power of a VHF frequency. A DC voltage in a positive direction is applied to a substrate in a film forming chamber, and the DC voltage is set to a lower voltage in a film forming chamber of a later layer in a stacking order. .

In the method for manufacturing a photovoltaic element, the photovoltaic element may be nipnipnip or pinp.
It is preferable to be formed as a photovoltaic element having an inpin three-layer tandem structure.

Further, the second i-type layer and the third i-type layer from the light incident side of the photovoltaic element having the three-layer tandem structure are:
It is preferable to deposit as non-single-crystal silicon germanium by a plasma CVD method using a high frequency power of a VHF frequency.

Further, it is preferable that the substrate is a belt-like substrate.

It is preferable to adopt a roll-to-roll system in which a roll-shaped substrate moves continuously in a plurality of film forming chambers.

The photovoltaic device of the present invention is characterized by being manufactured by any of the above methods.

The photovoltaic device manufacturing apparatus of the present invention is a photovoltaic device for manufacturing a tandem photovoltaic device made of a silicon-based non-single-crystal semiconductor by passing a substrate through a plurality of film forming chambers. The device manufacturing apparatus has a film forming chamber for depositing a plurality of i-type layers by a plasma CVD method using high-frequency power of a VHF frequency among i-type layers of a photovoltaic device having a tandem structure. In the film forming chamber for depositing the i-type layer, a means for applying a DC voltage in a positive direction to the substrate is provided, and the means for applying the DC voltage is lower in a film forming chamber of a later layer in a stacking order. It is characterized by being set to a voltage.

The above-mentioned positive direction is preferred.

In the apparatus for manufacturing a photovoltaic element, it is preferable that the means for applying the DC voltage in the positive direction is formed by a DC bias electrode and a DC power supply for applying a DC voltage to the electrode.

Further, the photovoltaic element may be nipnip
It is preferably formed as a photovoltaic element having a three-layer tandem structure of nip or pinpinpin.

Further, the second i-type layer and the third i-type layer from the light incident side of the photovoltaic element having the three-layer tandem structure are formed by plasma CVD using high frequency power of VHF frequency.
It is preferable that the film is deposited as non-single-crystal silicon germanium in a film forming chamber where the method is performed.

Preferably, the substrate is a belt-like substrate.

In addition, it is preferable to form a roll-to-roll apparatus in which a roll-shaped substrate moves continuously in a plurality of film forming chambers.

According to the present invention, a positive DC voltage is applied to the substrate and a negative DC electric field is applied to the substrate side to the i-type layer forming chamber for forming the deposited film with the high frequency power of the VHF frequency. As a result, the quality of the deposited film during high-speed deposition is improved.

Further, in the i-type layer for forming the deposited film with the high frequency power of the VHF frequency, the DC voltage to be applied is set lower as the layer is stacked in a later layer, so that the deposited film has a relatively high resistance and a thicker deposited film thickness. Even if the i-type layer is deposited and the surface of the deposited film on the substrate becomes high in resistance, the applied DC voltage is set lower as the deposited film is laminated, so that a spark or the like is applied from the DC voltage application electrode. No abnormal discharge occurs, the surface of the deposited film is charged up, and the semiconductor film in the course of manufacture does not cause dielectric breakdown, and the photovoltaic element to be manufactured does not cause characteristic failure.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings, but the present invention is not limited to these embodiments.

FIG. 1 is a schematic sectional view showing an example of an apparatus for realizing a method for manufacturing a photovoltaic element according to the present invention. FIG.
In the apparatus shown in (1), the band-shaped substrate is passed through six film forming chambers while being continuously moved, and a photovoltaic element having a two-layer tandem structure made of a silicon-based non-single-crystal semiconductor is manufactured on the substrate. The layer configuration of a photovoltaic device having a two-layer tandem structure made of a silicon-based non-single-crystal semiconductor is generally nipnip or pinpin. In this device, two i-type semiconductor layers are deposited by a plasma CVD method at a VHF frequency, and are stacked. A lower positive DC voltage is applied to the film forming chamber as the i-type layer becomes later.

In FIG. 1, a long strip-shaped substrate 101 is pulled out from a coiled state in an unwinding chamber 102, and chambers 103, 104, 105, 106,
7 and 108 sequentially, and wound in a coil shape in a winding chamber 109 provided with a winding mechanism (not shown). The unwinding chamber 102, each of the chambers 103 to 108, and the winding chamber 109 are each provided with a gas gate 110 and an adjacent chamber.
Connected by

Gas gate 1 passing through strip-shaped substrate 101
Each of the gates 10 is provided with a gate gas introduction pipe 111 near the center in the substrate transfer direction, and a gas such as H ₂ or He is introduced to form a gas flow from the center of the gas gate to an adjacent chamber. In addition, the mixture of the source gases in the adjacent chambers is prevented, and the source gases are separated.

Each of the chambers 103 to 108 is provided with a source gas introduction pipe 112, an exhaust pipe 113, a plate electrode 114 or a rod-shaped electrode 115, and a substrate heater 119, and a silicon-based non-single-crystal A semiconductor film is stacked.

In the apparatus shown in FIG.
Among 03 to 108, the discharge frequency of the chambers 104 and 107 is the VHF frequency of 105 MHz, and the discharge frequency of the other chambers 103, 105, 106, and 108 is the RF frequency of 13.56 MHz.

VHF frequency chambers 104 and 1
At 07, the high-frequency power is radiated from the rod-shaped electrode 115 connected to the high-frequency power supply 117 having the VHF frequency. On the other hand, in the RF frequency chamber, the high frequency power is supplied to the plate electrode 1 connected to the RF frequency high frequency power source 116.
Radiated from 14.

Further, a DC bias electrode 118 is provided separately from the rod-shaped electrode 115 in the film forming chambers of the chambers 104 and 107 at the VHF frequency, and a DC voltage is applied from a DC power supply 119.

In FIG. 1, the moving direction 120 of the substrate is from left to right. In the chambers 104 and 107 for depositing the i-type semiconductor layer with the high frequency power of the VHF frequency, the deposition films 104 and 107 are stacked on the substrate. It is performed in the order of

In the present invention, the DC voltage V1 applied to the chamber 104 and the DC voltage V2 applied to the chamber 107 are set to have a relationship of V1>V2> 0. Since a positive DC voltage is applied to the substrate and a negative DC electric field is formed on the substrate side, the film quality of the deposited film during high-speed deposition is improved. Can be

In the i-type layer in which the deposited film is formed with the high frequency power of the VHF frequency, the DC voltage to be applied is set lower as the layer is stacked, so that the deposited film is relatively high in resistance and has a large deposited film thickness. Even if the i-type layer is deposited and the surface of the deposited film on the substrate becomes high in resistance, the applied DC voltage is set lower as the deposited film is laminated, so that a spark or the like is applied from the DC voltage application electrode. No abnormal discharge occurs, the surface of the deposited film is charged up, and the semiconductor film in the course of manufacture does not cause dielectric breakdown, and the photovoltaic element to be manufactured does not cause characteristic failure.

Hereinafter, a method for manufacturing a photovoltaic device according to the present invention will be further described.

<DC Bias Voltage> In the present invention, the DC voltage applied to the film forming chamber is a positive voltage with respect to the substrate potential, preferably 0 to 500 V, more preferably 50 to 500 V.
From the range of up to 400 V, the voltage is set so that good film quality can be obtained in the deposited semiconductor film and spark and charge-up do not occur.

<Method of Applying DC Bias Voltage> In the present invention, as a method of applying a DC voltage to the film forming chamber, a method of providing a bias electrode for applying a bias in addition to the VHF discharge electrode inside the film forming chamber or a method of applying a VHF A method of superposing and applying a DC voltage to the discharge electrode together with the high-frequency power is exemplified. A method of superimposing and applying a DC voltage together with high-frequency power to the VHF discharge electrode requires a smaller number of electrodes and simplifies the structure of the film forming chamber, but choke the DC voltage application circuit so that the high-frequency power does not enter the circuit. It is necessary to cut off the high frequency by means such as a coil and to cut off the direct current by a capacitor or the like so that the direct current does not flow into the high frequency power supply.

<VHF Frequency> In the present invention, the VHF frequency used in the plasma CVD method is a frequency of 30 MHz or more and 500 MHz or less. Within that range,
A relatively high frequency region is selected when increasing the plasma density to increase the deposition rate, and a relatively low frequency region is selected when long wavelength uniformity is desired.

<Strip-shaped Substrate> The strip-shaped substrate preferably used in the present invention can be moved at the time of forming a semiconductor layer, has little deformation and distortion at a temperature required for film deposition, and has a desired strength. In addition, those having conductivity are preferable. Specifically, a metal thin film made of stainless steel, aluminum, iron, or the like, or a heat-resistant resin made of polyimide, Teflon, or the like, which has been subjected to a conductive treatment on its surface, or the like can be given.

<Plasma CVD Method> In the present invention, a plasma CVD method using a high frequency VHF is performed in at least two film forming chambers. The discharge frequency in the other film forming chamber may be the RF frequency or the microwave frequency.

When the deposited film is, for example, a silicon-based non-single-crystal film, a gas containing a gasizable compound containing at least silicon atoms is introduced into the film forming chamber and becomes a raw material of the semiconductor film. It may contain a gasizable compound containing a germanium atom, a gasizable compound containing a carbon atom, or a mixed gas of the compound.

As the gasizable compound containing a silicon atom, a chain or cyclic silane compound is used. Specifically, for example, SiH ₄ , Si ₂ H ₆ , Si
F ₄ , SiFH ₃ , SiF ₂ H ₂ , SiF ₃ H, Si ₃ H ₈ ,
SiD ₄ , SiHD ₃ , SiH ₂ D ₂ , SiH ₃ D, SiF
D ₃ , SiF ₂ D ₂ , Si ₂ D ₃ H ₃ , (SiF ₂ ) ₅ , (Si
F ₂ ) ₆ , (SiF ₂ ) ₄ , Si ₂ F ₆ , Si ₃ F ₈ , Si ₂ H ₂
F ₄ , Si ₂ H ₃ F ₃ , SiCl ₄ , (SiCl ₂ ) ₅ , Si
Br ₄ , (SiBr ₂ ) ₅ , Si ₂ Cl ₆ , SiHCl ₃ , S
Examples thereof include those in a gas state such as iH ₂ Br ₂ , SiH ₂ Cl ₂ and Si ₂ Cl ₃ F ₃ , and those which can be easily gasified. Here, D represents deuterium.

When the deposited film is amorphous silicon germanium, the gaseous compound containing germanium atoms specifically as a source gas is GeH ₄ , Ge
D ₄ , GeF ₄ , GeFH ₃ , GeF ₂ H ₂ , GeF ₃ H, G
eHD ₃ , GeH ₂ D ₂ , GeH ₃ D, Ge ₂ H ₆ , Ge ₂ D ₆
And the like.

When the deposited film is made of amorphous silicon carbide, the gaseous compounds containing carbon atoms specifically as the source gas include CH ₄ , CD ₄ , and C _n H _{2n + 2}
(N is an integer), C _n H _2n (n is an integer), C ₂ H ₂ , C
₆ H ₆ , CO ₂ , CO and the like.

Examples of the substance introduced into the p-type layer or the n-type layer for controlling valence electrons include Group III atoms and Group V atoms in the periodic table.

Examples of useful starting materials for introducing Group III atoms include boron hydrides such as B ₂ H ₆ and boron halides such as BF ₃ for the purpose of introducing boron atoms. Can be mentioned.

Effectively used as a starting material for introducing a group V atom is specifically PH ₃ for introducing a phosphorus atom.
Hydrogen phosphorus etc., and halogenated phosphorus PF ₅ or the like.
In addition, AsH _{3 and the} like can be mentioned.

The compound capable of being gasified is H ₂ , H
It may be appropriately diluted with a gas such as e, Ne, Ar, Xe, or Kr and introduced into the film formation chamber.

<Tandem Photovoltaic Device> In the present invention, the tandem photovoltaic device refers to a photovoltaic device having a structure in which a plurality of photovoltaic devices are connected in series.

In the photovoltaic device having a tandem structure, a plurality of photovoltaic devices having different light absorption wavelength ranges are stacked so that the band gaps become narrower in the light incident direction.
A wider wavelength range of the incident light can be utilized, and the photoelectric conversion efficiency is improved.

In a tandem photovoltaic element,
Since light is absorbed by the plurality of photoelectric conversion layers, the thickness of each photoelectric conversion layer can be reduced, and a light deterioration phenomenon called the Stepler-Lonski effect can be suppressed.

The layer configuration of a tandem photovoltaic element made of a silicon-based non-single-crystal semiconductor is nipnip.
Or a two-pin tandem structure of pinpin, nipni
A three-layer tandem structure of pnip or pinpinpin can be mentioned. Among them, the three-layer tandem structure is excellent in that a wider light wavelength range can be utilized.

In the case of a photovoltaic device having a three-layer tandem structure,
From the light incident side, the light transmitted through the first photoactive layer is transmitted to the second photoactive layer, and the first and second photoactive layers are transmitted to the third photoactive layer.
Since the light transmitted through the second photoactive layer enters, if the band gap is the same, the first <second <
It is necessary to increase the film thickness in the order of the third. If the band gaps of the second and third photoactive layers are made narrower than the first, the film thickness can be suppressed from being increased. However, the film thickness tends to be larger than that of the first photoactive layer. For manufacturing, it is desirable to apply a high-speed deposition method.

As described above, a plurality of photovoltaic elements having a tandem structure made of a silicon-based non-single crystal and having different light absorption wavelength ranges are arranged such that the band gaps become narrower in the light incident direction. In the case of stacking, as a material having a narrow band gap, non-single-crystal silicon germanium, non-single-crystal silicon tin, microcrystalline silicon, or the like can be given.

[0061]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples.

(Example 1) In this example, using a manufacturing apparatus having the structure shown in FIG. 1 and using the method of the present invention, ni composed of six silicon-based non-single-crystal films on a stainless steel substrate was used.
A pnip two-layer tandem solar cell was manufactured.

The two i-type layers are deposited by a plasma CVD method at a VHF frequency while applying a DC voltage to the film forming chamber.
The applied DC voltage was set to be lower in the order of deposition.

In the apparatus shown in FIG.
A stainless substrate 101 (SUS430-BA) having a width of 356 mm, a width of 356 mm, and a thickness of 0.15 mm was placed in the unwinding chamber 10.
2 through a gas gate 110 from chambers 103, 104, 105, 106, 1
07 and 108, it was set so as to be wound in a coil shape on a bobbin of the winding chamber 109, and was stretched without slack by a tension applying mechanism (not shown).

Next, the inside of each of the chambers 102 to 109 was once evacuated to 1 Pa or less by the exhaust means of each chamber. While evacuating continuously, He gas is supplied from a gas introduction pipe 112 connected to gas supply means (not shown) of each chamber.
Each gas was introduced at 100 sccm, and the internal pressure of each chamber was maintained at 100 Pa by adjusting the opening of an exhaust valve (not shown) of the exhaust pipe 113.

In this state, the belt-shaped substrate was continuously moved at a moving speed of 600 mm per minute by a substrate transfer mechanism (not shown) connected to the bobbin of the winding chamber 109.

Next, a substrate heater 119 provided in each plasma discharge chamber and a substrate temperature monitor (not shown) determine
The heating was controlled so that the band-shaped substrate 101 moving in each chamber reached a predetermined temperature.

When the substrate 101 was uniformly heated in each chamber, the introduction of the He gas was stopped while continuing the heating, and the gas to the gas introduction pipe 112 was switched to a source gas containing SiH ₄ .

Each gas gate 110 is supplied with H ₂ at a rate of 1000 sccm as a source gas separating gas from a gate gas inlet pipe 111 connected to gas supply means (not shown).
Introduced.

Next, high-frequency power of RF frequency and VHF frequency is supplied from a high-frequency power source to the discharge electrodes 114 and 115 of each chamber to generate a discharge in each chamber, to decompose the raw material gas into plasma, and to move the moving band-shaped substrate. 1
01, a stacked film of a silicon-based non-single-crystal film was deposited to form a semiconductor film of a two-layer tandem solar cell made of a silicon-based non-single-crystal semiconductor.

The discharge frequency of the chambers 104 and 107 was 105 MHz, the discharge electrodes were rod-shaped,
The discharge frequency of 3, 105, 106 and 108 is 13.56.
At MHz, the discharge electrode was flat.

Further, a DC voltage of 300 V is applied to the bias electrode of the chamber 104 of the VHF frequency through which the substrate passes first in a positive direction with respect to the belt-like substrate of the earth potential, and the chamber 107 of the VHF frequency through which the substrate passes later. A DC voltage of 100 V was applied to the bias electrode in a positive direction with respect to the strip substrate at the ground potential.

Table 1 shows the film forming conditions in each chamber.

[0074]

[Table 1]

Such a film deposition is carried out with a length of 400 on the belt-like substrate.
m, the supply of discharge power to each chamber, the introduction of source gas, and the heating of the strip substrate are stopped, each chamber is sufficiently purged, and the strip substrate and the inside of the apparatus are sufficiently cooled. After that, the apparatus was opened to the atmosphere, and the strip-shaped substrate on which the semiconductor laminated film was formed and wound on the bobbin in the winding chamber was taken out.

Further, the strip-shaped substrate taken out is continuously processed by a continuous modularization apparatus, and a 60 nm transparent electrode is formed on the entire surface of the semiconductor laminated film formed by the apparatus of the present invention as a transparent electrode.
A thin-film Ag electrode was formed at a constant gap as a current collecting electrode, and a 35 cm square nipnip structure two-layer tandem solar cell module was continuously formed.

The characteristics of the produced solar cell module were evaluated at 25 ° C. under simulated sunlight irradiation of AM1.5 (100 mW / cm ² ).

As a result of the characteristic evaluation, the average photoelectric conversion efficiencies of the solar cell modules produced were determined by the chambers 104 and 107.
When the average photoelectric conversion efficiency of the solar cell module when no bias voltage was applied was set to 1, it was 1.4 times.

When the occurrence rate of characteristic failure due to short-circuiting of the produced solar cell module was examined,
4. The non-defective rate when no DC voltage was applied to 107 was 1
In the comparison, when 300 V was applied to the chamber 104 and 100 V was applied to the chamber 107, the non-defective rate was 95, 100 V was applied to the chamber 104, and 300 was applied to the chamber 107.
The non-defective rate when V was applied was 35.

Table 2 shows changes in conversion efficiency and non-defective product ratio when a solar cell module is manufactured by changing the combination of DC voltages.

[0081]

[Table 2]

From this, it was confirmed that the method of the present invention can achieve both the conversion efficiency of the photovoltaic element having the tandem structure and the yield rate.

(Embodiment 2) FIG. 2 is a schematic diagram showing an apparatus for realizing the method of the present invention used in this embodiment. The device shown in FIG. 2 has three RF frequency chambers added to the device of FIG. 1, and the i-type layer is VHF from the substrate side.
Frequency, VHF frequency, RF frequency high frequency plasma C
Nipnipnip or pin deposited by VD method
It is possible to manufacture a semiconductor laminated film of a photovoltaic device having a pinpin three-layer tandem structure.

In FIG. 2, reference numeral 201 denotes a belt-like substrate;
Is the unwinding chamber, 203, 204, 205, 206, 20
7, 208 are chambers, 220, 221, 222 are 1
A plasma CVD chamber with an RF frequency of 3.56 MHz, 209 is a winding chamber, and 210 is a gas gate.

In this example, a solar cell having a three-layer tandem structure of a nipnip structure consisting of nine silicon-based non-single-crystal films on a stainless steel substrate was manufactured by the method of the present invention using the apparatus shown in FIG. .

The three i-type layers are formed by high-frequency plasma CVD at VHF frequency, VHF frequency and RF frequency from the substrate side.
Chambers 204 and 207 at VHF frequency
A positive DC voltage was applied to the film forming chamber. The applied DC voltage was set so as to be lower in the order of deposition.

More specifically, a DC voltage of 200 V is applied to the bias electrode of the chamber 204 at the VHF frequency through which the substrate passes first in a positive direction with respect to the belt-like substrate at the ground potential, and the VHF frequency at the VHF frequency through which the substrate passes later. Chamber 20
A DC voltage of 100 V was applied to the bias electrode 7 in a positive direction with respect to the belt-like substrate at the ground potential.

Table 1 shows the film forming conditions in each chamber.

[0089]

[Table 3]

Thereafter, in the same manner as in Example 1, a solar cell module having a three-layer tandem structure of a nipnipnip structure comprising nine silicon-based non-single-crystal films on a stainless steel substrate was manufactured by the method of the present invention.

The characteristics of the produced solar cell module were evaluated at a temperature of 25 ° C. under irradiation of simulated sunlight of Am1.5 (100 mW / cm ² ).

As a result of the characteristic evaluation, the average photoelectric conversion efficiency of the produced solar cell module was determined by the chambers 204 and 207.
The average photoelectric conversion efficiency of the solar cell module in the case where no DC voltage was applied was 1.4, which was 1.4 times.

When the occurrence rate of the characteristic failure due to the short circuit of the produced solar cell module was examined,
4, the non-defective rate when no DC voltage was applied to 207 was 1
As a comparison, when the voltage of 200 V was applied to the chamber 204 and the voltage of 100 V was applied to the chamber 207, the non-defective rate was 98, which was good with almost no change.

From the above, it was confirmed that the method of the present invention can achieve both the conversion efficiency and the yield rate of the photovoltaic element having the tandem structure.

Example 3 A 35 cm square nipnipnip structure 3 was formed in the same manner as in Example 2 except that the discharge frequency in the discharge chambers 204 and 207 was changed to 20 MHz.
A solar cell module having a layered tandem structure was continuously manufactured.

The characteristics of the produced solar cell module were evaluated at a temperature of 25 ° C. under irradiation of simulated sunlight of Am1.5 (100 mW / cm ² ).

As a result of the characteristic evaluation, the average photoelectric conversion efficiency of the produced solar cell module was determined by the chambers 204 and 207.
The average photoelectric conversion efficiency of the solar cell module when no DC voltage was applied was 1.25 times when compared to 1.

When the occurrence rate of characteristic failure due to short-circuit of the produced solar cell module was examined,
4, the non-defective rate when no DC voltage was applied to 207 was 1
In comparison with the case of 00, 200% was applied to the chamber 204 and 100V was applied to the chamber 207.

From the above, it was confirmed that the method of the present invention can achieve both the conversion efficiency and the yield of the photovoltaic element having the tandem structure.

(Example 4) Example 2 was repeated except that the discharge frequency in the discharge chambers 204 and 207 was changed to 500 MHz.
In the same manner as in, a solar cell module having a 35 cm square nipnipnip structure and a three-layer tandem structure was continuously manufactured.

The characteristics of the produced solar cell module were evaluated at a temperature of 25 ° C. under irradiation of Am1.5 (100 mW / cm ² ) simulated sunlight.

As a result of the characteristic evaluation, the average photoelectric conversion efficiency of the produced solar cell module was determined by the chambers 204 and 207.
Was 1.45 times when the average photoelectric conversion efficiency of the solar cell module when no DC voltage was applied was set to 1.

Further, when the occurrence rate of characteristic failure due to the short circuit of the produced solar cell module was examined,
4, the non-defective rate when no DC voltage was applied to 207 was 1
As a comparison, when the voltage of 200 V was applied to the chamber 204 and the voltage of 100 V was applied to the chamber 207, the non-defective rate was 95, which was good with almost no change.

From the above, it was confirmed that the method of the present invention can achieve both the conversion efficiency of the photovoltaic element having the tandem structure and the yield rate.

Example 5 A 35 cm square nipni was manufactured in the same manner as in Example 2 except that the DC voltages applied to the discharge chambers 204 and 207 were changed to 200 V and 150 V, respectively.
A three-layer tandem solar cell module having a pnip structure was continuously manufactured.

Then, the characteristics of the produced solar cell module were evaluated at a temperature of 25 ° C. under irradiation of Am1.5 (100 mW / cm ² ) simulated sunlight.

As a result of the characteristic evaluation, the average photoelectric conversion efficiency of the produced solar cell module was determined by the chambers 204 and 207.
The average photoelectric conversion efficiency of the solar cell module when no DC voltage was applied was 1.43 times as compared with 1.

When the occurrence rate of the characteristic failure due to the short-circuit of the produced solar cell module was examined,
4, the non-defective rate when no DC voltage was applied to 207 was 1
As a comparison, the non-defective rate when 200 V was applied to the chamber 204 and 150 V was applied to the chamber 207 was 93, which was good with almost no change.

From the above, it was confirmed that the method of the present invention can achieve both the conversion efficiency and the yield of the photovoltaic element having the tandem structure.

[0110]

As described above, according to the present invention,
Since a positive DC voltage is applied to the substrate and a negative DC electric field is formed on the substrate side in the film forming chamber for the i-type layer for forming the deposited film with the high frequency power of the VHF frequency, The film quality of the deposited film can be improved.

Further, in the i-type layer for forming the deposited film with the high frequency power of the VHF frequency, the DC voltage to be applied is set to be lower as the order of lamination is later, so that the resistance is relatively high and the deposited film thickness is large. Even if the i-type layer is deposited and the surface of the deposited film on the substrate becomes high in resistance, the applied DC voltage is set lower as the deposited film is laminated, so that a spark or the like is applied from the DC voltage application electrode. No abnormal discharge occurs, the surface of the deposited film does not charge up, and the semiconductor film in the process of manufacture does not cause dielectric breakdown. A highly efficient low-deterioration tandem-structure photovoltaic element can be manufactured.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing an example of a configuration of an apparatus for realizing a method for manufacturing a photovoltaic element of the present invention.

FIG. 2 is a schematic cross-sectional view showing an example of the configuration of an apparatus for realizing the method for manufacturing a photovoltaic element of the present invention.

[Explanation of symbols]

101 Strip-shaped substrate 102 Unwinding chamber 103, 104, 105, 106, 107, 108 Chamber 109 Winding chamber 110 Gas gate 111 Gate gas introduction tube 112 Source gas introduction tube 113 Exhaust tube 114 Plate electrode 115 Rod electrode 116 RF power source of RF frequency 117 High frequency power supply of VHF frequency 118 DC bias electrode 119 DC power supply 201 Strip-shaped substrate 202 Unwinding chamber 203, 204, 205, 206, 207, 208, 2
20, 221, 222 chamber 209 winding chamber 210 gas gate

Continuation of the front page (72) Inventor Shotaro Okabe 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Yuzo Koda 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Tadashi Sawayama 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Takahiro Yajima 3-30-2, Shimomaruko 3-chome, Ota-ku, Tokyo Canon Inc. (72) Invention Person Masahiro Kanai 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term in Canon Inc. (reference) 5F051 AA05 BA14 CA03 CA16 CA22 DA15

Claims (12)

[Claims] 1. A method for manufacturing a photovoltaic device, comprising: passing a substrate through a plurality of film forming chambers to produce a tandem-structured photovoltaic device made of a silicon-based non-single-crystal semiconductor on the substrate; Among the i-type layers of the electromotive element, a plurality of i
CV using high frequency power of VHF frequency for mold layer
Plasma CVD deposited by D method and using high frequency power of VHF frequency
A DC voltage in a positive direction is applied to the substrate in a film forming chamber for a plurality of i-type layers to be deposited by the deposition method, and the DC voltage is set to a lower voltage in a film forming chamber of a later layer in a stacking order. A method for manufacturing a photovoltaic element. 2. The photovoltaic element according to claim 2, wherein said photovoltaic element is nipnipni.
The method for manufacturing a photovoltaic device according to claim 1, wherein the photovoltaic device is manufactured as a photovoltaic device having a three-layer tandem structure of p or pinpinpin. 3. A photovoltaic device having a three-layer tandem structure, wherein the second i-type layer and the third i-type layer from the light incident side are VH
3. The method according to claim 2, wherein the non-single-crystal silicon germanium is deposited by a plasma CVD method using a high frequency power of an F frequency. 4. The method according to claim 1, wherein the substrate is a band-shaped substrate. 5. The photovoltaic device according to claim 1, wherein a roll-to-roll system in which a roll-shaped substrate moves continuously in a plurality of film forming chambers is adopted. Production method. 6. A photovoltaic device manufactured by the method according to claim 1. Description: 7. A photovoltaic device manufacturing apparatus for manufacturing a tandem photovoltaic device made of a silicon-based non-single-crystal semiconductor on a substrate by passing the substrate through a plurality of film forming chambers. Among the i-type layers of the electromotive element, a plurality of i
CV using high frequency power of VHF frequency for mold layer
A film forming chamber for depositing by the method D, a means for applying a positive DC voltage to the substrate is provided in the film forming chamber for depositing the plurality of i-type layers, and the DC voltage is applied An apparatus for manufacturing a photovoltaic element, wherein the means is set to a lower voltage in a deposition chamber of a later layer. 8. The light according to claim 7, wherein the means for applying the positive direct-current voltage is formed by a direct-current bias electrode and a direct-current power supply for applying a direct-current voltage to the bias electrode. Equipment for manufacturing electromotive force elements. 9. The photovoltaic element according to claim 9, wherein said photovoltaic element is nipnipni.
The photovoltaic device manufacturing apparatus according to claim 7, wherein the device is manufactured as a photovoltaic device having a three-layer tandem structure of p or pinpinpin. 10. The second i-type layer and the third i-type layer from the light incident side of the photovoltaic element having a three-layer tandem structure have V
10. The photovoltaic element manufacturing apparatus according to claim 9, wherein the non-single-crystal silicon germanium is deposited in a film forming chamber for performing a plasma CVD method using a high frequency power of an HF frequency. 11. The apparatus for manufacturing a photovoltaic device according to claim 7, wherein said substrate is a strip-shaped substrate. 12. The photovoltaic device according to claim 7, wherein the photovoltaic device is formed as a roll-to-roll apparatus in which a roll-shaped substrate moves continuously in a plurality of film forming chambers. Manufacturing equipment.