JP2002134774A - Method for forming silicon-based thin film, the silicon- based thin film and photovoltaic element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a silicon-based thin film, having superior characteristics in a short tact time at a higher film forming rate, a silicon-based thin film thus formed, and a photovoltaic element employing that silicon-based thin film and having superior characteristics, adhesion, resistance to environment, and the like. SOLUTION: At least a part of a discharge space generating a plasma is covered with at least a part of a substrate, a high-frequency introducing section faces the substrate, the distance between the high-frequency introducing section and the substrate is 3 mm-30 mm, pressure in the discharge space is between 90 Pa (0.68 Torr) or higher and 1.5×104 Pa (113 Torr or lower), and a residence time τ, defined by τ=592×V×P/Q, is between 0.01 sec and 10 sec, where P (Pa) is the pressure in the discharge space.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a silicon-based thin film, a silicon-based thin film, and a photovoltaic element such as a sensor formed by depositing at least one set of pin junctions.

[0002]

2. Description of the Related Art The high-frequency plasma CVD method is one of the excellent methods for mass-producing silicon-based thin films from the viewpoint that a large area and low-temperature formation are easy and the process throughput is improved. Considering solar cells as an example of applying silicon-based thin films to products, compared to existing energy using fossil fuels, solar cells using silicon-based thin films have an inexhaustible energy source and a power generation process. Although it has the advantage of being clean, further cost reduction is required to promote its use. To this end, establishment of a technique for improving a film forming rate by a high-frequency plasma CVD method is one of the heavy technical issues.

Electric frequency plasma CV with increased film forming speed
Regarding the D method, Japanese Patent Publication No. 7-105354 describes that the high frequency is f (MHz) and the distance between the substrate and the electrode is d (c).
m), when f is in the range of 25 to 150 MHz, focusing on the relationship between the high frequency f and the distance d between the substrate and the electrode, f / d is preferably in the range of 30 to 100 MHz / cm. In particular, it is disclosed that a method in which d is performed in a region of 1 to 3 cm or a pressure of 0.1 to 0.5 mbar is preferable.

Japanese Patent Application Laid-Open No. H11-330520 discloses a method for producing a crystalline silicon-based thin film layer, which includes a silane-based gas and a hydrogen gas, a pressure in a reaction chamber is set to 5 Torr or more, and a distance between a substrate and an electrode is 1 cm. It is disclosed that a silicon-based thin film layer manufactured under the condition of “within” can be formed with a concept, and a photoelectric conversion device using the same has high conversion efficiency.

However, as described above, the former high-frequency plasma CVD method which has already been disclosed focuses on the value of f / d. In particular, when d is small, good quality with a high deposition rate and a small defect density is obtained. Although it is said that a film can be formed, d is set to a minimum value of 1 cm due to the influence of other phenomena, and there is no mention of a method of forming a film at a higher speed in a smaller d region. On the other hand, with respect to the latter manufacturing method, the distance between the deposition surface of the substrate and the opposing electrode surface is within 1 cm, and the substrate is mounted on the discharge electrode. is there.

In the former method, the characteristics of the film are evaluated solely by the evaluation of the defect density of a single film. When this method is applied when the films are stacked at the time of forming a device or the like, damage to an underlayer is caused. No particular mention is made of effects on close selection, environmental resistance, and the like.

Further, the latter focuses on only the flow rate ratio between the silane-based gas and the hydrogen gas with respect to the source gas, and the residence time defined by the volume of the discharge space and the flow rate of the source gas depends on the film quality and the reaction rate. The effect on by-product formation is not mentioned.

[0008]

SUMMARY OF THE INVENTION The present invention provides a photovoltaic device having excellent performance at a lower cost and with a shorter tact time and excellent characteristics at a higher electric speed. It is an object of the present invention to provide a method of forming a silicon-based thin film, a formed silicon-based thin film, and a photovoltaic using the silicon-based thin film and having excellent characteristics, adhesion, and environmental resistance.

[0009]

The present invention is a method for introducing a raw material gas into a vacuum vessel and forming a silicon-based thin film on a substrate introduced into the vacuum vessel by using a high-frequency plasma CVD method. A part of a discharge space in which plasma is generated is covered by at least a part of the substrate, the high-frequency introduction unit and the substrate are opposed to each other, and a distance between the high-frequency introduction unit and the substrate is 3 mm. 30 mm or less and the pressure in the discharge space is 90 Pa (0.68 Torr).
Not less than 1.5 × 10 ⁴ Pa (113 Torr), and the volume of the discharge space in which the plasma is generated is V
(M ³ ), and the flow rate of the raw material gas is set to Q (cm ³ / min (n
normal)), when the pressure in the discharge space is P (Pa), the residence time τ defined by τ = 592 × V × P / Q
Is 0.01 second or more and 10 seconds or less.

According to the present invention, there is provided a method of forming a silicon-based thin film on a substrate introduced into the vacuum vessel by using a high-frequency plasma CVD method by introducing a raw material gas into the vacuum vessel. A part of the space is covered by at least a part of the substrate, the high-frequency introduction unit and the substrate are opposed to each other, and a distance between the high-frequency introduction unit and the substrate is 3 mm or more and 30 mm or less; Pressure within 90 Pa (0.68 Torr) and 1.5 × 10
⁴ Pa (113 Torr) or less, the volume of the discharge space in which the plasma is generated is V (m ³ ), the flow rate of the source gas is Q (cm ³ / min (normal)), and the pressure of the discharge space is P (Pa), τ = 592 ×
Provided is a silicon-based thin film characterized by being formed so that the residence time τ defined by V × P / Q is not less than 0.01 seconds and not more than 10 seconds.

[0011] The present invention relates to a method for producing at least one set of pi on a substrate.
Fewer photovoltaic elements including semiconductor layers consisting of n-junctions
One i-type semiconductor layer guides the source gas into the vacuum vessel.
Into the vacuum vessel,
In the method of forming a silicon-based thin film using a CVD method,
Part of the discharge space where plasma is generated
It is covered by at least a part of the plate,
The high-frequency introduction unit and the substrate
Is 3 mm or more and 30 mm or less in the discharge space.
Pressure is 90 Pa (0.68 Torr) or more and 1.5 × 1
0^FourPa (113 Torr) or less, and the plasma
Is the volume of the discharge space where V (m ^Three), The raw material
The flow rate of gas is Q (cm^Three/ Min (normal)),
When the pressure in the discharge space is P (Pa), τ = 592
The residence time τ defined by × V × P / Q is 0.01 seconds or less
Of a silicon-based thin film characterized by being 10 seconds or less
Including a silicon-based thin film formed by a forming method
And a photovoltaic element characterized by the following.

It is preferable that the source gas is a mixed gas containing a silicon hydride compound and hydrogen. Preferably, the source gas contains a germanium hydride compound, and the silicon-based thin film is made of an alloy of silicon and germanium. It is preferable that the silicon-based thin film is a silicon-based thin film including microcrystals having a Scherrer radius of 20 nm or more. It is preferable that the flow rate of hydrogen in the source gas relative to the hydrogenated silicon compound is 30 times or more. It is preferable that the silicon-based thin film has a Raman scattering intensity due to a crystalline component that is three times or more as large as a Raman scattering intensity due to an amorphous component. The silicon-based thin film is formed by X-ray or electron diffraction (2
It is preferable that the ratio of the diffraction intensity of 20) is 70% or more of the total diffraction intensity. High-frequency introduced power is A
(W) The value of the high-frequency density A / B is 0.05 to 2 W / cm ³ when the product of the area of the electric-frequency introduction section and the distance between the high-frequency introduction section and the substrate is B (cm ³ ). Is preferred.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As a result of intensive studies to solve the above-mentioned problems, the present inventors have introduced a source gas into a vacuum vessel, and applied a high-frequency plasma CVD method on a substrate introduced into the vacuum vessel. A method of forming a silicon-based thin film using, wherein a part of the discharge space where plasma is generated is covered with at least a part of the substrate, and the high-frequency introduction unit and the substrate are opposed to each other. The distance between the high-frequency introduction unit and the substrate is 3 mm or more and 30 mm or less, and the pressure in the discharge space is 90 Pa (0.68 Torr) or more.
× 10 ⁴ Pa (113 Torr) or less, the volume of the discharge space in which the plasma is generated is V (m ³ ), and the flow rate of the source gas is Q (cm ³ / min (norma).
l)), when the pressure in the discharge space is P (Pa), τ
= 592 x V x P / Q, the residence time τ is 0.
When the time is from 01 seconds to 10 seconds, it is possible to form a silicon-based thin film having excellent characteristics with a low defect density at a higher speed, and the silicon-based thin film is formed on a substrate by at least one set of pin bonding. By using at least a part of at least one i-type semiconductor layer of a photovoltaic element including a semiconductor layer comprising, a photovoltaic element having good photoelectric exchange efficiency, excellent adhesion, and excellent environmental resistance can be obtained. It was found that it was possible to form at low cost.

With the above configuration, the following operations are provided.

In a method in which a raw material gas is introduced into a vacuum vessel and a silicon-based thin film is formed on the substrate introduced into the vacuum vessel using a high-frequency plasma CVD method, the distance between the high-frequency introduction portion and the substrate is reduced. It is considered that the plasma density per discharge space volume increases, and it becomes possible to form reactive species contributing to the formation of a deposited film at a high density, thereby realizing a higher deposition rate.

On the other hand, when the distance between the high-frequency introducing portion and the substrate is reduced, the electron density in the plasma increases, and the amount of generated ions may increase accordingly. Since ions are accelerated by electrostatic attraction in the sheath region in the discharge space, they distort the arrangement of atoms in the bulk as ion bombardment or cause voids in the film,
It is thought that it can be a hindrance to the formation of a high-quality silicon-based thin film. Here, by increasing the pressure in the film formation space, ions in the plasma are
Increased chance of collision with active species, etc. is thought to reduce the ion impact force and reduce the amount of ions themselves, which is expected to reduce ion impact relatively it can. On the other hand, when the pressure is increased, the plasma concentrates near the high frequency introduction part, and a phenomenon occurs in which it is difficult to improve the uniformity when forming a silicon-based thin film over a large area.

Further, when SiH ₄ is used as a silicon hydride compound as a source gas, when the distance between the high-frequency introducing section and the substrate is reduced as described above, the high-frequency power absorbed per unit discharge space volume increases. By doing
It is thought that decomposition of ₄ is promoted, which can contribute to an increase in the film formation rate. Here, it is considered that the formation of the silicon-based thin film is performed through a process of moving a reactive species from the gas phase to the substrate surface, diffusing the substrate surface, and depositing,
In order for the surface to be sufficiently diffused and the process of performing a chemical bond at a stable site to be sufficiently performed, it is considered that it is desirable that the SiH ₃ radical be a reactive species in consideration of the lifetime of the radical and the like. Furthermore, when various radicals such as SiH and SiH ₂ become reactive species, the reaction form on the surface becomes complicated, and the defect density is thought to increase accordingly. Therefore, only the SiH ₃ radical functions as the reactive species. It is considered desirable to do so. Where S
The cause of the increase in the density of radicals such as iH and SiH ₂ is that, due to the increase in the electron density in the plasma, the SiH ₄ gas in the plasma atmosphere is depleted and the SiH ゃ Si
It is considered that this is because the rate of disappearance of radicals such as SiH and SiH ₂ decreases because the secondary reaction between the radicals such as H ₂ and SIH ₄ decreases.

In order to prevent the density of radicals such as SiH and SiH _{2 from} increasing in an atmosphere in which the electron density in the plasma is increased, gas is introduced so as to suppress a decrease in the density of SiH _{4 in} the plasma atmosphere. It is considered that this is made possible by controlling the plasma. Here, as parameters of the plasma, the volume of the discharge space in which the plasma is generated is V (m ³ ), and the flow rate of the raw material gas is Q (cm ^3).
/ Min (normal)) and the pressure in the discharge space is P (P
In the case of a), a decrease in the density of SiH ₄ in the plasma atmosphere was suppressed by focusing on the residence time τ (second) defined by τ = 592 × V × P / Q as a parameter for plasma control. It is considered that plasma can be generated. This is based on the finding that the SiH ₄ gas is decomposed when the residence time is longer, so that SiH ₄ is depleted, and when the residence time is too short, the gas phase reaction does not proceed sufficiently. .

In order to obtain a high-quality silicon-based thin film,
It is considered important to control the residence time in addition to the above parameters such as the distance pressure between the high-frequency introduction unit and the substrate.

In view of the above, as a result of intensive studies conducted by the present inventor, it has been found that, in order to form a silicon-based thin film having a low defect density and excellent characteristics at a higher speed, the high-frequency introducing section and the substrate are required. Is 3 mm or more and 30 mm or less, and the pressure in the discharge space is 90 Pa (0.68 Torr).
r) or more and 1.5 × 10 ⁴ Pa (113 Torr) or less, and the volume of the discharge space where the plasma is generated is V
(M ³ ), and the flow rate of the raw material gas is set to Q (cm ³ / min (n
normal)), when the pressure in the discharge space is P (Pa), the residence time τ defined by τ = 592 × V × P / Q
Is set to 0.01 seconds or more and 10 seconds or less, a sufficient amount of SiH ₄ is supplied into the plasma atmosphere, and a desired silicon-based thin film can be formed. Here, a method of forming by a CVD method using a high frequency of 1 MHz to 300 MHz is particularly preferable.

In a photovoltaic element having a pin junction, the i-type semiconductor layer functioning as a light absorbing layer accounts for a large proportion of the entire semiconductor layer, and therefore, it is desirable to form the i-type semiconductor layer at a higher deposition rate. In particular, it is desirable that the film formation rate is 2.0 nm or more. In view of realizing such high-speed film formation, the distance between the high-frequency introduction unit and the substrate described above is 3 mm or more and 30 mm or more.
The following is assumed. A range of 3 mm to 9 mm is more preferable.

In forming the device such as a photovoltaic element, in the above-described range, it is possible to prevent the components, film quality, characteristics, and the like of the underlayer from being deteriorated by the reducing action of hydrogen in the plasma atmosphere. Adverse effects on the system can be eliminated. In the case where a transparent conductive film made of a metal oxide such as zinc oxide is used as the underlayer, reduction in the transmittance of the transparent conductive film due to reduction and reduction in the characteristics of the photovoltaic element accompanying the reduction can be particularly prevented. It is effective.

Still another effect is that the adhesion between the silicon-based thin film and the underlayer is improved. This is due to the active surface diffusion of a large amount of SiH ₃ radicals.
Since the deposited film is formed while always relaxing the stress strain near the surface, it is considered that this effect is exerted. In addition, since the hydrogen partial pressure is relatively increased, rapid release of hydrogen atoms incorporated in the silicon network is suppressed, and plastic flow caused by the generation of irregular regions in the silicon network and cracks caused by the flow are caused. The formation of a silicon-based thin film with excellent film quality and adhesion is possible because it can prevent the occurrence of agglomeration and agglomeration. It is believed that an electromotive element can be provided. Further, by forming a stable Si—Si bond, it is possible to suppress the breakage of the bond during light irradiation, and thus an effect of suppressing light degradation in the amorphous silicon-based thin film is exhibited.

In view of the effect on the substrate, the adhesion, the environmental resistance, and the effect of reducing the light deterioration rate, the pressure is 100 Pa
(0.75 Torr) or more and 5000 Pa (37.5 Ton)
rr) or less, and more preferably, the residence time is 0.1 seconds or more and 3 seconds or less.

The above effect can be expected even when germanium hydride is contained in the source gas as an equivalent effect of replacing Si atoms with Ge atoms. In order to be able to absorb sunlight in a wider wavelength region, the pin-junction i-type semiconductor layer near the light incident side has a wide band gap, and the band gap becomes narrower as the farther pin junction is formed. It is preferable to form a photovoltaic element having a plurality of such pin junctions, and to increase the Ge content in the i-type semiconductor layer as the pin junction becomes farther from the light incident side.

In the case where the i-type semiconductor substantially functioning as a light absorbing layer in the silicon-based thin film, particularly a photovoltaic device having a pin junction, is an i-type semiconductor layer containing a crystalline phase, There is an advantage that a light deterioration phenomenon due to the Stäbler-Wronski effect, which is a problem, can be suppressed.

On the other hand, a silicon-based thin film containing a crystal phase is
It is known that a problem in the case of adopting it for a type semiconductor layer is that crystal grain boundaries affect both majority carriers and minority carriers to deteriorate performance. In order to suppress the influence of the crystal grain boundaries, it is considered that one of effective means is to increase the crystal grain size in the i-type semiconductor to lower the crystal grain boundary density. In particular, it is preferable that the crystal has a large crystal grain size in the traveling direction of the carrier, and the Scherrer radius is 20 nm when the traveling direction of the carrier is a surface normal.
It is preferable that it is above.

An element for increasing the crystal grain size is to increase the crystal orientation. If the deposition of the film proceeds in a random crystal orientation, it is thought that the crystal grains collide during the growth process and the size of the crystal grains is relatively small. It is considered that by making the properties uniform, random collision between crystal grains can be suppressed, and as a result, the crystal grain size can be further increased.

In crystalline silicon having a diamond structure, the (220) plane has the highest atomic density in the plane, and the silicon atoms in the outermost surface of the growth have the other three of the four bonds as other bonds. Since this structure is a growth surface, it is possible to form a silicon-based thin film having good adhesion and weather resistance because the structure is covalently bonded to silicon atoms. .

According to the ASTM card, in the non-oriented crystalline silicon, the ratio of the diffraction intensity of the (220) plane to the total of the diffraction intensity for 11 reflections from the low angle side is about 23%,
A structure in which the ratio of the diffraction intensity of the (220) plane exceeds 23% has the orientation in the plane direction. Especially (2
In the structure in which the ratio of the diffraction intensity of the (20) plane is 70% or more, the above effect is further promoted, which is particularly preferable.

A method of forming a silicon-based thin film containing a crystal phase as described above by a plasma CVD method using a high frequency can shorten the process time and lower the process temperature as compared with the solid phase reaction. This is advantageous for cost reduction. In particular, in a photovoltaic element having a pin junction, by applying the present invention to an i-type semiconductor layer having a large film thickness, this effect is greatly exerted.

Here, in order to form a silicon-based thin film containing a crystal phase by a plasma CVD method using a high frequency using a mixed gas containing a silicon hydride compound and hydrogen as a source gas, a silicon hydride compound must be formed. In addition to adjusting the ratio of hydrogen gas, it is important to control the residence time. This is because, in a plasma with a high electron density, when the radical density of SiH or SiH ₂ is increased, crystallization with this as a nucleus is likely to occur in the discharge space and on the surface of the deposited film. In the former case, the formation of reaction by-products may act as a hindrance factor to the enlargement of the crystal grain size in the latter case.

By controlling the residence time, generation of reaction by-products such as polysilane can be suppressed, and crystalline silicon having relatively large crystal grain boundaries can be formed. Further, the value of the high frequency density A / B is 0.05 to 2 W, where A (W) is the high frequency introduction power, and B (cm ³ ) is the product of the high frequency introduction area and the distance between the high frequency introduction section and the substrate. / Cm ³
By introducing a high frequency as described above, it is possible to form a silicon-based thin film having higher crystallinity and excellent orientation. This is considered to be because the generation of a large amount of H atoms promotes structural relaxation to increase crystallinity, and the passivation action breaks bonds having a weak bonding force to increase the orientation.

Next, the components of the photovoltaic device of the present invention will be described. FIG. 1 is a schematic sectional view showing an example of a photovoltaic device according to an embodiment of the present invention. 101 in the figure
Denotes a substrate, 102 denotes a semiconductor layer, 103 denotes a second transparent conductive layer, and 104 denotes a current collecting electrode. 101-1 is a base, 101-2 is a metal layer, and 101-3 is a first transparent conductive layer. These are components of the substrate 101.

(Base) As the base 101-1, a metal,
A plate-like member or a sheet-like member made of resin, glass, ceramics, semiconductor bulk, or the like is preferably used. The surface may have fine irregularities. A structure in which light is incident from the substrate side using a transparent substrate may be employed. Further, by forming the base into a long shape, continuous film formation using a roll-to-roll method can be performed. In particular, flexible materials such as stainless steel and polyimide are used for the substrate 101-.
It is suitable as the material of (1).

(Metal Layer) The metal layer 101-2 has a role as an electrode and a role as a reflection layer that reflects light reaching the base 101-1 and reuses it in the semiconductor layer 102. The materials include Al, Cu, Ag, Au,
CuMg, AlSi, or the like can be suitably used. As the forming method, methods such as vapor deposition, sputtering, electrodeposition, and printing are suitable. The metal layer 101-2 preferably has irregularities on its surface. Accordingly, the optical path length of the reflected light in the semiconductor layer 102 can be extended, and the short-circuit current can be increased. When the base 101-1 has conductivity, the metal layer 101-2 need not be formed.

(First Transparent Conductive Layer) First Transparent Conductive Layer 1
01-3 has a role of increasing the irregular reflection of incident light and reflected light and extending the optical path length in the semiconductor layer 102. Also,
It has a role of preventing the element of the metal layer 101-2 from diffusing or migrating into the semiconductor layer 102 and preventing the photovoltaic element from shunting. Furthermore, by having an appropriate resistance, it has a role of preventing a short circuit due to a defect such as a pinhole in the semiconductor layer. Further, it is desirable that the first transparent conductive layer 101-3 has an unevenness on the surface thereof, similarly to the metal layer 101-2. The first transparent conductive layer 101-3 is preferably made of a conductive oxide such as ZnO or ITO, and is preferably formed using a method such as evaporation, sputtering, CVD, or electrodeposition. A substance that changes conductivity may be added to these conductive conductive oxides.

The zinc oxide layer is preferably formed by a method such as sputtering or electrodeposition, or by a combination of these methods.

The conditions for forming a zinc oxide film by the sputtering method are greatly affected by the method, the type and flow rate of gas, the internal pressure, the input power, the film formation rate, and the substrate temperature. For example, when a zinc oxide film is formed by a DC magnetron sputtering method using a zinc oxide target, the gas type is A
r, Ne, Kr, Xe, Hg, 0 2 , and the like, the flow rate varies depending on the size and pumping speed of the apparatus, for example when the volume of the film-forming space is 20 liters, 100 sccm from 1sccm is desirable.

The internal pressure during film formation is 1 × 10 ⁻⁴ Torr.
To 0.1 Torr is desirable. The input power depends on the size of the target, but is preferably from 10 W to 100 KW when the diameter is 15 cm. The preferable range of the substrate temperature varies depending on the film forming speed, but when forming the film at 1 μm / h, the substrate temperature is preferably from 70 ° C. to 450 ° C.

The conditions for forming the zinc oxide film by the electrodeposition method are preferably to use an aqueous solution containing nitrate ions and zinc ions in a corrosion-resistant container. The concentration of nitrate ion and zinc ion is from 0.001 mol / l to 1.0 m
ol / l, preferably 0.01 mol / l.
It is more preferably in the range of 1 to 0.5 mol / 1, and even more preferably in the range of 0.1 mol / l to 0.25 mol / l. The source of nitrate ion and zinc ion is not particularly limited, and zinc nitrate, which is a source of both ions, or a water-soluble nitrate such as ammonium nitrate, which is a source of nitrate ion, and zinc ion It may be a mixture of zinc salts such as zinc sulfate as a source. Furthermore, it is also preferable to add a carbohydrate to these aqueous solutions in order to suppress abnormal growth and improve adhesion. The type of carbohydrate is not particularly limited, but glucose (glucose),
Monosaccharides such as fructose (fructose), disaccharides such as maltose (maltose) and saccharose (sucrose), polysaccharides such as dextrin and starch, and mixtures thereof can be used. The amount of carbohydrate in the aqueous solution depends on the type of carbohydrate, but is generally 0.001 g / 1.
To 300 g / 1, preferably 0.00
More preferably, it is in the range of 5 g / l to 100 g / l, even more preferably in the range of 0.01 g / l to 60 g / l. When depositing a zinc oxide film by an electrodeposition method, it is preferable that the substrate on which the zinc oxide film is deposited in the aqueous solution is used as a cathode and zinc, platinum, carbon or the like is used as an anode. At this time, the current density flowing through the load resistor is 1
It is preferably from 0 mA / dm ² to 10 A / dm ² .

(Substrate) The body 101-
A substrate 101 is formed by laminating a metal layer 101-2 and a first transparent conductive layer 101-3 on the substrate 1 as needed. Further, an insulating layer may be provided on the substrate 101 as an intermediate layer in order to facilitate integration of elements.

(Semiconductor Layer) Si is used as a main material of the semiconductor layer 102 which is a part of the silicon-based thin film of the present invention. Instead of Si, an alloy of Si and C or Ge may be used. The semiconductor layer 102 contains hydrogen and / or halogen atoms at the same time. The preferred content is 0.1 to 40 atomic%. Further, the semiconductor layer 102 may contain oxygen, nitrogen, and the like. The semiconductor layer contains a Group III element to be a p-type semiconductor layer, and contains a Group V element to be an n-type semiconductor layer. As the electric durability of the p-type layer and the n-type layer, those having an activation energy of 0.2 eV or less are preferable, and those having an activation energy of 0.1 eV or less are optimal. The specific resistance is preferably 100 Ωcm or less,
The optimal value is 1 Ωcm or less. In the case of a stack cell (a photovoltaic element having a plurality of pin junctions), p near the light incident side
It is preferable that the band gap of the in-junction i-type semiconductor layer is wide and the band gap becomes narrower as the farther pin junction is formed. As the doped layer (p-type layer or n-type layer) on the light incident side, a crystalline semiconductor with little light absorption or a semiconductor with a wide band gap is suitable.

As an example of a stack cell in which two sets of pin junctions are stacked, a combination of an i-type silicon-based semiconductor layer, from the light incident side (amorphous silicon semiconductor layer, amorphous silicon semiconductor layer), (amorphous silicon semiconductor layer, amorphous (A silicon germanium semiconductor layer). Further, as an example of a photovoltaic element in which three sets of pin junctions are stacked, a combination of i-type silicon-based semiconductor layers, from the light incident side (amorphous silicon semiconductor layer, amorphous silicon semiconductor layer, amorphous silicon germanium semiconductor layer), ( An amorphous silicon semiconductor layer, an amorphous silicon germanium semiconductor layer, and an amorphous silicon germanium semiconductor layer). The absorption coefficient (α) of light (630 nm) for the i-type semiconductor layer is 5000 cm.
^-1 or more, solar simulator (AM1.5, 100
mW / cm ² ) photoconductivity (σ)
p) is 10 × 10 ⁻⁵ / cm or more, and the darkness (σd) is 1
0 × 10 ⁻⁶ S / cm or less, Urbach energy by constant photocurrent method (CPM) is 55 m
It is preferably eV or less. As the i-type semiconductor layer,
Slightly p-type and n-type ones can also be used. When a silicon germanium semiconductor layer is used for the i-type semiconductor layer, germanium is contained in at least one of the p / i interface and the n / i interface for the purpose of reducing the interface state and increasing the open circuit voltage. A configuration in which an i-type semiconductor layer is inserted may be employed.

The semiconductor layer 102 as a component of the present invention will be further described. FIG. 3 shows a semiconductor layer 1 having a set of pin junctions as an example of a photovoltaic element of the present invention.
It is a typical sectional view showing 02. In the figure, reference numeral 102-1 denotes a semiconductor layer having a first conductivity type, and further, an i-type semiconductor layer 102-2 formed of a silicon-based thin film of the present invention and a semiconductor layer 102-3 having a second conductivity type are laminated. I do. In a semiconductor layer having a plurality of pin junctions, at least one of the semiconductor layers preferably has the above-described configuration.

(Method for Forming Semiconductor Layer) In order to form the silicon-based thin film and the semiconductor layer 102 of the present invention, a high-frequency plasma CVD method is suitable. Hereinafter, high frequency plasma CV
A preferred example of a procedure for forming the semiconductor layer 102 by the method D will be described. (1) The inside of the vacuum chamber for semiconductor formation which can be reduced in pressure is reduced to a predetermined deposition pressure. (2) A material gas such as a source gas or a dilution gas is introduced into the deposition chamber, and the deposition chamber is set to a predetermined deposition pressure while exhausting the deposition chamber by a vacuum pump. (3) The substrate 101 is set to a predetermined temperature by a heater. (4) The electric frequency oscillated by the high frequency power supply is introduced into the deposition chamber. The method of introducing into the deposition chamber is as follows: when the high frequency is microwaves, it is guided by a waveguide and introduced into the deposition chamber through a dielectric window such as quartz, alumina, aluminum nitride, or when the high frequency is VHF or RF. For example, there is a method in which the material is guided by a coaxial cable and introduced into a deposition chamber via a metal electrode. (5) Plasma is generated in the deposition chamber to decompose the source gas, and a deposited film is formed on the substrate 101 disposed in the deposition chamber. This procedure is repeated a plurality of times as needed to form the semiconductor layer 102.

The conditions for forming the semiconductor layer 102 are as follows: the substrate temperature in the deposition chamber is 100 to 450 ° C., and the pressure is 0.067.
Pa (0.5 mTorr) to 1.5 × 10 ⁴ Pa (11
3 Torr), high frequency power density 0.001-2 W /
cm ³ is a preferable condition. Further, when the silicon-based thin film of the present invention is formed, the distance between the high-frequency introducing section and the substrate is 3 mm or more and 9 mm or less, and the pressure is 90 P or less.
a (0.68 Torr) or more and 1.5 × 10 ⁴ Pa (11
3 Torr) or less, the volume of the discharge space where plasma is generated is V (m ³ ), and the flow rate of the raw material gas is Q (cm ³ / m ³ ).
in (normal)), and the pressure in the discharge space is P (Pa)
It is necessary to control the plasma conditions so that the residence time τ defined by τ = 592 × V × P / Q is not less than 0.01 seconds and not more than 10 seconds. In the case of forming a silicon-based thin film containing microcrystals having a Scherrer radius of 20 nm or more according to the present invention, the high-frequency power density is preferably 0.05 to 2 W / cm ³ .

Silicon-based thin film and semiconductor layer 10 of the present invention
Source gas suitable for forming Si ₂ is SiH ₄ , Si ₂ H
_In the case of using a hydrogenated silicon compound such as ₆ or an alloy, a gasizable compound containing Ge or C, such as GeH ₄ or CH _4, may be diluted with a hydrogen gas gas and introduced into the deposition chamber. desirable. Further, an inert gas such as He may be added. Further, a gasifiable compound containing nitrogen, oxygen or the like may be added as a source gas or a diluent gas. B ₂ H ₆ , BF ₃ or the like is used as a dopant gas for turning the semiconductor layer into a p-type layer. Further, as a dopant gas for converting the semiconductor layer into an n-type layer, P
H ₃ and PF ₃ are used. In the case of depositing a thin film of a crystal phase or a layer having a small light absorption or a wide band gap such as SiC, it is preferable to increase the ratio of the diluent gas to the source gas and to introduce a high frequency power having a relatively high power density.

(Second transparent conductive layer) Second transparent conductive layer 1
Reference numeral 03 denotes an electrode on the light incident side, and can also serve as an anti-reflection film by appropriately setting its film thickness. The second transparent conductive layer 103 is a semiconductor layer 102
Is required to have a high transmittance in a wavelength region that can absorb light and to have a low resistivity. Preferably 550
The transmittance in nm is 80% or more, more preferably 85%.
% Is desirable. The resistivity is 5 × 10 ^-3 Ωc
m, more preferably 1 × 10 ⁻³ Ωcm or less. As a material of the second transparent conductive layer 103, ITO, ZnO, can be suitably used an In ₂ 0 ₃ and the like. As the formation method, methods such as vapor deposition, CVD, spray, spin-on, and immersion are suitable. A substance that changes conductivity may be added to these materials.

(Current Collecting Electrode) The current collecting electrode 104 is provided on the transparent electrode 103 to improve current collecting efficiency. As the forming method, a method of forming a metal of an electrode pattern by sputtering using a mask, a method of printing a conductive paste or a solder paste, a method of fixing a metal wire with a conductive paste, and the like are preferable.

Incidentally, if necessary, protective layers may be formed on both surfaces of the photovoltaic element. At the same time, an auxiliary material such as a steel plate may be used in combination on the back surface (light incident side and reflection side) of the photovoltaic element.

[0052]

EXAMPLES In the following examples, the present invention will be specifically described by taking a solar cell as an example of a photovoltaic element, but these examples do not limit the content of the present invention at all.

Example 1 The photovoltaic element shown in FIG. 4 was formed by the following procedure using the deposited film forming apparatus 201 shown in FIG. FIG. 4 is a schematic sectional view showing an example of a photovoltaic device having a silicon-based thin film of the present invention. In the figure,
The same members as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. The semiconductor layer of this photovoltaic element includes an amorphous n-type semiconductor layer 102-1A and an amorphous i-type semiconductor layer 10-1.
2-2A and the microcrystalline p-type semiconductor layer 102-3A. That is, this photovoltaic element is a so-called pin
Type single cell photovoltaic element.

FIG. 2 is a schematic sectional view showing an example of a deposited film forming apparatus for producing a silicon-based thin film and a photovoltaic element according to the present invention. The deposited film forming apparatus 201 shown in FIG.
Substrate sending container 202, semiconductor forming vacuum container 211
To 219, the substrate take-up container 203 is
It is configured by coupling through 1 to 230. A strip-shaped conductive substrate 204 is set in the deposition film forming apparatus 201 through each container and each gas gate. The strip-shaped conductive substrate 204 is placed in the substrate transfer container 20.
The substrate is unwound from the bobbin provided in the second bobbin 2 and wound on another bobbin in the substrate winding container 203.

The semiconductor forming vacuum vessels 211 to 219
Each has a deposition chamber for forming a plasma generation region. In general, the deposition chamber is a discharge space where plasma is generated,
The upper and lower sides are limited by the conductive substrate and the high-frequency introducing section, and the lateral direction is limited by a discharge plate provided so as to surround the high-frequency introducing section.

The flat-plate high-frequency introduction unit 241 in the deposition chamber
To 249, high-frequency power is applied from high-frequency power supplies 251 to 259 to generate glow discharge, whereby the source gas is decomposed and a semiconductor layer is deposited on the conductive substrate 204. The high-frequency introducing sections 241 to 249 face the conductive substrate 204 and have a height adjustment mechanism (not shown). By the height mechanism, the distance between the conductive substrate and the high-frequency introducing portion can be changed, and at the same time, the volume of the discharge space can be changed. Further, gas introduction pipes 231 to 239 for introducing a source gas and a dilution gas are connected to the respective vacuum chambers 211 to 219 for semiconductor formation.

Although the deposited film forming apparatus 201 shown in FIG. 2 has nine semiconductor forming vacuum vessels, in the following embodiments, it is necessary to generate a glow discharge in all the semiconductor forming vacuum vessels. However, the presence or absence of glow discharge in each container can be selected according to the layer configuration of the photovoltaic element to be manufactured. In addition, in each semiconductor forming vacuum container,
A film formation region adjustment plate (not shown) for adjusting the contact area between the conductive substrate 204 and the discharge space in each deposition chamber is provided.

First, prior to the formation of the photovoltaic element, an experiment for confirming the film formation rate of the amorphous i-type semiconductor layer was performed. Strip-shaped substrate made of stainless steel (SUS430BA) (width 50 cm, length 200 m, thickness 0.125 mm)
Is sufficiently degreased and washed, and is attached to a continuous sputtering device (not shown).
nm Al thin film was sputter deposited. Further, using a ZnO target, a ZnO thin film having a thickness of 1.2 μm was
A strip-shaped conductive substrate 204 was formed by sputtering on the thin film.

Next, a bobbin around which the conductive substrate 204 is wound is mounted on the substrate delivery container 202, and the conductive substrate 204 is loaded with the gas gate on the loading side, and the semiconductor forming vacuum containers 211 and 2.
12, 213, 214, 215, 216, 217, 21
8, 219 was passed through the gas gate on the carry-out side to the substrate take-up container 203, and the tension was adjusted so that the strip-shaped conductive substrate 204 did not slack. Then, the substrate delivery container 202 and the semiconductor formation vacuum containers 211, 212, 21
3, 214, 215, 216, 217, 218, 21
9. The substrate take-up container 203 is moved to 6.7 × 10 ⁻⁴ Pa (5 × 10
^-8 Torr) or less.

Next, while operating the vacuum evacuation system, the source gas and the diluent gas were supplied from the gas introduction pipe 238 to the semiconductor formation vacuum vessel 218. Here, the deposition chamber in the semiconductor formation vacuum container 218 has a length of 1 m in the longitudinal direction and a width of 5 m.
The thing of 0 cm was used. In addition, the semiconductor-forming vacuum container 2
The vacuum chamber for forming a semiconductor other than 18 is
An H ₂ gas of 00 cm ³ / min (normal) was supplied, and at the same time, an H ₂ gas of 500 sccm was supplied as a gate gas from each gate gas supply pipe (not shown) to each gas gate. In this state, adjust the exhaust capacity of the vacuum exhaust system,
The pressure in the semiconductor forming vacuum vessel 218 was adjusted to a predetermined pressure. The forming conditions are as shown in the forming conditions of 218 in Table 1.

When the pressure in the semiconductor forming vacuum container 218 was stabilized, the movement of the conductive substrate 204 in the direction from the substrate sending container 202 to the substrate take-up container 203 was started.

Next, a high frequency power is introduced from a high frequency power supply 258 to a high frequency introducing portion 248 in the semiconductor forming vacuum vessel 218, and a distance between the conductive substrate and the electric frequency introducing portion is determined by a height adjusting mechanism. A glow discharge was generated in the deposition chamber in the semiconductor formation vacuum vessel 218 while changing the predetermined distance shown in FIG. 4 to form an amorphous i-type semiconductor layer on the conductive substrate 204. Here, semiconductor forming vacuum vessel 218
Has a high frequency of 60 MHz and a power density of 100
While adjusting to be mW / cm ³ , the light was introduced from an electric frequency introduction part 248 made of a metal electrode made of Al. The film thickness of each of the formed amorphous i-type semiconductor layers is represented by a cross section T
It was measured by EM observation to determine the film formation rate. Table 2 shows the values of the obtained film forming rates. Here, the amorphous i-type semiconductor layer in which the distance between the conductive substrate and the high-frequency introducing portion is 2 mm is
The uniformity of the film thickness was poor, and an average film forming rate could not be obtained.

Next, a photovoltaic element was prepared. vacuum
While operating the exhaust system, the semiconductor forming vacuum vessel 217,
218, 219 to gas introduction pipes 237, 238, 239
Raw material gas and diluent gas were supplied. Here semiconductor formation
The discharge chamber in the vacuum chamber 218 has a longitudinal length of one.
m and a width of 50 cm were used. Also, semiconductor formation
For forming semiconductors other than vacuum chambers 217, 218, and 219
200cm from the gas inlet tube to the vacuum vessel^Three/ Min (n
normal) H_TwoSupply gas, and at the same time
Gate gas supply pipe to each gas gate as gate gas
500 sccm H _TwoGas was supplied. Vacuum in this state
The vacuum capacity for semiconductor formation is adjusted by adjusting the exhaust capacity of the exhaust system.
The pressure in 17, 218, 219 is adjusted to a predetermined pressure.
Was. The forming conditions are as shown in Table 1.

Semiconductor forming vacuum vessels 217, 218, 2
When the pressure in the substrate 19 is stabilized, the substrate delivery container 2
The movement of the conductive substrate 204 in the direction from 02 to the substrate take-up container 203 was started.

Next, the semiconductor forming vacuum vessels 217 to 21
9, high-frequency power sources 257 to 249
To 259, the vacuum chamber 2 for semiconductor formation
Glow discharge is generated in the deposition chambers 17 to 219, and an amorphous n-type semiconductor layer (thickness: 3) is formed on the conductive substrate 204.
0 nm), amorphous i-type semiconductor layer (film thickness 500 n)
m), a microcrystalline p-type semiconductor layer (10 nm thick) was formed to form a photovoltaic element. Here, the semiconductor forming vacuum container 217 has a frequency of 13.56 MHz and a power density of 5 mW.
/ Cm ³ of high-frequency power from a high-frequency introduction unit 247 made of an Al metal electrode and into the semiconductor forming vacuum vessel 218 by a height adjustment mechanism in the same manner as the amorphous i-type semiconductor. While changing the distance between the parts to a predetermined distance shown in Table 2 (excluding 2 mm), a high frequency having a frequency of 60 MHz was applied at a power density of 100 mW / c.
The vacuum container 21 for semiconductor formation is adjusted from the high-frequency introducing portion 248 made of an Al metal electrode while adjusting to be m ^3.
9 has a frequency of 13.56 MHz and a power density of 30 mW /
A high frequency power of cm ³ was introduced from a high frequency introduction unit 249 made of a metal electrode made of Al. Here, for each photovoltaic element, the film thickness was made uniform using a film formation region adjusting plate according to the obtained film formation speed. Next, using a continuous modularization device not shown,
The formed band-shaped photovoltaic element was processed into a solar cell module of 36 cm × 22 cm.

The photoelectric conversion efficiency of each solar cell module was measured using a solar simulator (AM 1.5, 100 mW / cm).
It was measured using ² ). Table 2 shows the results.

As described above, the photovoltaic device in which the distance between the conductive substrate and the electric-frequency introducing portion is 3 mm or more and 30 mm or less exhibits excellent photoelectric conversion efficiency, and particularly, the photovoltaic device in which the distance is 3 mm or more and 9 mm or less. In the device, the film formation rate of the amorphous i-type semiconductor layer was 2.0 nm / sec or more, which was particularly excellent. From the above, it can be seen that the solar cell module including the photovoltaic element of the present invention has excellent features.

(Example 2) The photovoltaic element shown in FIG. 4 was formed by the following procedure using the deposited film forming apparatus 201 shown in FIG. FIG. 4 is a schematic sectional view showing an example of a photovoltaic device having a silicon-based thin film of the present invention. In the figure.
The same members as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. The semiconductor layer of this photovoltaic element includes an amorphous n-type semiconductor layer 102-1A and an amorphous i-type semiconductor layer 10-1.
2-2A and the microcrystalline p-type semiconductor layer 102-3A. That is, this photovoltaic element is a so-called pin
Type single cell photovoltaic element.

As in the first embodiment, the belt-shaped conductive substrate 20
4 is mounted on the deposition film forming apparatus 201, and the substrate sending container 202, the semiconductor forming vacuum containers 211 and 21 are prepared.
2, 213, 214, 215, 216, 217, 21
8, 219 The substrate take-up container 203 is evacuated to 6.7 × 10 ⁻⁴ Pa (5
(× 10 ⁻⁶ Torr) or less.

Next, while operating the vacuum evacuation system, the gas introduction pipe 2 was introduced into the vacuum chambers 217, 218, and 219 for semiconductor formation.
Source gas and dilution gas were supplied from 37, 238, and 239. Here, the discharge chamber in the semiconductor formation vacuum vessel 218 used had a length of 1 m in the longitudinal direction and a width of 50 cm. Further, the vacuum chambers 217, 218, 2
The vacuum vessel for semiconductor formation other than 19 is
An H ₂ gas of 00 cm ³ / min (normal) was supplied, and at the same time, an H ₂ gas of 500 sccm was supplied as a gate gas from each gate gas supply pipe (not shown) to each gas gate. In this state, adjust the exhaust capacity of the vacuum exhaust system,
The pressure inside the semiconductor formation vacuum containers 217, 218, and 219 was adjusted to a predetermined pressure. The forming conditions are as shown in Table 3.

Semiconductor forming vacuum vessels 217, 218, 2
When the pressure in the substrate 19 is stabilized, the substrate delivery container 2
The movement of the conductive substrate 204 in the direction from 02 to the substrate take-up container 203 was started.

Next, the semiconductor forming vacuum vessels 217 to 21
9, high-frequency power sources 257 to 249
To 259, the vacuum chamber 2 for semiconductor formation
Glow discharge is generated in the deposition chambers 17 to 219, and an amorphous n-type semiconductor layer (thickness: 3) is formed on the conductive substrate 204.
0 nm), amorphous i-type semiconductor layer (film thickness 500 n)
m), a microcrystalline p-type semiconductor layer (10 nm thick) was formed to form a photovoltaic element. Here, the semiconductor forming vacuum container 217 has a frequency of 13.56 MHz and a power density of 5 mW.
/ Cm ³ of high-frequency power from the high-frequency introduction section 247 made of an Al metal electrode, the distance between the conductive substrate and the high-frequency introduction section was set to 5 mm in the semiconductor forming vacuum vessel 218, and the frequency was 100 MHz. While adjusting the high frequency so that the power density becomes 150 mW / cm ³ , a 13.56 MHz frequency and a power density of 30 mW / cm ³ are supplied from the high frequency introducing section 248 made of an Al group of metal electrodes to the vacuum vessel 219 made of semiconductor. High-frequency power was introduced from a high-frequency introduction unit 249 made of a metal electrode made of Al.

Next, using a continuous module device (not shown), the formed band-shaped photovoltaic element was
Into a solar cell module. The above operation was performed for each of the pressures in the semiconductor forming vacuum container 218 shown in Table 4. At this time, the flow rate of the raw material gas introduced into the semiconductor forming vacuum vessel 218 is adjusted so that the above-mentioned τ = 0.5 seconds, and further adjusted so that the ratio of SiH ₄ to H ₂ becomes 1: 9. Shed.

The photoelectric conversion efficiency of the solar cell module prepared as described above was measured using a solar simulator (AM).
1.5, 100 mW / cm ² ). Further, the adhesiveness between the conductive substrate and the semiconductor layer was examined by using a grid tape method (interval of cuts of 1 mm, number of squares of 100). A solar cell module whose initial photoelectric conversion efficiency has been measured in advance is used at a temperature of 85 ° C. and a humidity of 85%.
In a dark place for 30 minutes and then 70 minutes
Lower the temperature to 20 ° C and hold for 30 minutes.
After this cycle of returning the temperature to 85 ° C. and the humidity of 85% was repeated 100 times, the photoelectric conversion efficiency was measured again, and the change in the photoelectric conversion efficiency by the temperature and humidity test was examined. In addition, a solar cell module whose initial photoelectric conversion efficiency has been measured in advance is 5
AM 1.5, 100 mW / cm while maintaining at 0 ° C.
After irradiating the artificial sunlight of No. ² for 500 hours, the photoelectric conversion efficiency was measured again, and the change of the photoelectric conversion efficiency by the light deterioration test was examined. Table 4 shows the results.

From Table 4, it can be seen that the solar cell module including the photovoltaic element manufactured at a pressure in the semiconductor formation container 218 of 90 Pa or more and 15000 Pa or less has a photoelectric conversion efficiency, a peeling test, a temperature and humidity test, and a light deterioration rate. It is clear that the solar cell module including the photovoltaic element manufactured at 100 Pa or more and 5000 Pa or less has excellent characteristics particularly in the peel test.

Example 3 The photovoltaic element shown in FIG. 4 was formed by the following procedure using the deposited film forming apparatus 201 shown in FIG. FIG. 4 is a schematic sectional view showing an example of a photovoltaic device having a silicon-based thin film of the present invention. In the figure,
The same members as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. The semiconductor layer of this photovoltaic element includes an amorphous n-type semiconductor layer 102-1A and an amorphous i-type semiconductor layer 10-1.
2-2A and a microcrystalline p-type semiconductor 102-3A. That is, this photovoltaic element is a so-called pin type single cell photovoltaic element.

As in the first embodiment, the belt-shaped conductive substrate 20
4 is prepared and installed in the deposited film forming apparatus 201, and the substrate sending container 202, the semiconductor forming vacuum containers 211 and 21 are prepared.
2, 213, 214, 215, 216, 217, 21
8, 219 The substrate take-up container 203 is evacuated to 6.7 × 10 ⁻⁴ Pa (5
(× 10 ⁻⁶ Torr) or less.

Next, while operating the vacuum evacuation system, the gas introduction pipe 2 was introduced into the semiconductor formation vacuum vessels 217, 218, and 219.
Source gas and dilution gas were supplied from 37, 238, and 239. Here, the discharge chamber in the semiconductor formation vacuum vessel 218 used had a length of 1 m in the longitudinal direction and a width of 50 cm. Further, the vacuum chambers 217, 218, 2
The vacuum vessel for semiconductor formation other than 19 is
An H ₂ gas of 00 cm ³ / min (normal) was supplied, and at the same time, an H ₂ gas of 500 sccm was supplied as a gate gas from each gate gas supply pipe (not shown) to each gas gate. In this state, adjust the exhaust capacity of the vacuum exhaust system,
The pressure inside the semiconductor formation vacuum containers 217, 218, and 219 was adjusted to a predetermined pressure. The forming conditions are as shown in Table 5.

Semiconductor forming vacuum vessels 217, 218, 2
When the pressure in the substrate 19 is stabilized, the substrate delivery container 2
The movement of the conductive substrate 204 in the direction from 02 to the substrate take-up container 203 was started.

Next, the semiconductor forming vacuum vessels 217 to 21
9, high-frequency power sources 257 to 249
To 259, the vacuum chamber 2 for semiconductor formation
Glow discharge is generated in the deposition chambers 17 to 219, and an amorphous n-type semiconductor layer (thickness: 3) is formed on the conductive substrate 204.
0 nm), amorphous i-type semiconductor layer (film thickness 500 n)
m), a microcrystalline p-type semiconductor layer (10 nm thick) was formed to form a photovoltaic element. Here, the semiconductor forming vacuum container 217 has a frequency of 13.56 MHz and a power density of 5 mW.
/ Cm ³ from the electric-frequency introduction unit 247 made of a metal electrode made of Al, the distance between the conductive substrate and the high-frequency introduction unit in the vacuum chamber 218 for semiconductor formation is set to 5 mm, and the frequency is 60 MHz. High frequency, power density of 1
A high-frequency power having a frequency of 13.56 MHz and a power density of 30 mW / cm ³ was supplied to the vacuum chamber 219 for semiconductor formation from the high-frequency introduction section 248 formed of an Al-type metal electrode while adjusting the power to be 00 mW / cm ³ . It was introduced from an electric frequency introduction unit 249 made of a metal electrode. Next, the formed strip-shaped photovoltaic element was processed into a solar cell module of 36 cm × 22 cm using a continuous modularization device (not shown). The above operation was performed with the pressure inside the semiconductor forming vacuum vessel 218 at each residence time shown in Table 6. At this time, the flow rate of the raw material gas introduced into the semiconductor formation vacuum vessel 218 is adjusted so as to realize each residence time, and further, SiH ₄ and H ₂
Was adjusted so that the ratio was 1:10.

The photoelectric conversion efficiency of the solar cell module prepared as described above was measured using a solar simulator (AM).
1.5, 100 mW / cm ² ). Further, the adhesiveness between the conductive substrate and the semiconductor layer was examined by using a grid tape method (interval of cuts of 1 mm, number of squares of 100). A solar cell module whose initial photoelectric conversion efficiency has been measured in advance is used at a temperature of 85 ° C. and a humidity of 85%.
In a dark place for 30 minutes and then 70 minutes
Lower the temperature to 20 ° C and hold for 30 minutes.
After this cycle of returning the temperature to 85 ° C. and the humidity of 85% was repeated 100 times, the photoelectric conversion efficiency was measured again, and the change in the photoelectric conversion efficiency by the temperature and humidity test was examined. In addition, a solar cell module whose initial photoelectric conversion efficiency has been measured in advance is 5
While maintaining the temperature at 0 ° C., the AM1. 5, 100mW / cm
² of pseudo sunlight was irradiated for 500 hours, to measure the photoelectric conversion efficiency was again examined the change in photoelectric conversion efficiency due to photo-deterioration test. Table 6 shows the results.

From Table 6, it can be seen that the solar cell module including the photovoltaic element manufactured with a residence time in the semiconductor formation container 218 of 0.01 seconds or more and 10 seconds or less has a photoelectric conversion efficiency, a peeling test, a temperature and humidity test, It is clear that each item of the photodeterioration rate is excellent, and in particular, a solar cell module including a photovoltaic element manufactured in 0.1 seconds or more and 3.0 seconds or less has excellent characteristics in a peel test.

Example 4 The photovoltaic element shown in FIG. 5 was formed by the following procedure using the deposited film forming apparatus 201 shown in FIG. FIG. 5 is a schematic sectional view showing an example of a photovoltaic device having a silicon-based thin film of the present invention. In the figure,
The same members as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. The semiconductor layers of this photovoltaic element include amorphous n-type semiconductor layers 102-1A, 102-4, and 102-7, and amorphous i-type semiconductor layers 102-2A, 102-5, and 10-5.
2-8 and the microcrystalline p-type semiconductor layers 102-3A and 102-
6, 102-9. That is, this photovoltaic element is a so-called pinpinpin type triple cell photovoltaic element.

As in the first embodiment, the belt-shaped conductive substrate 20
4 is mounted on the deposition film forming apparatus 201, and the substrate sending container 202, the semiconductor forming vacuum containers 211 and 21 are prepared.
2, 213, 214, 215, 216, 217, 21
8, 219 The substrate take-up container 203 is evacuated to 6.7 × 10 ⁻⁴ Pa (5
(× 10 ⁻⁶ Torr) or less.

Next, while operating the vacuum evacuation system, the gas introduction pipes 231-2 are introduced into the semiconductor formation vacuum vessels 211-219.
From 39, a source gas and a dilution gas were supplied. Here, the discharge chamber in the vacuum chambers 212, 215, and 218 for semiconductor formation used had a length of 1 m in the longitudinal direction and a width of 50 cm. Further, from each gate gas supply pipe (not shown), 500 sccm of H ₂ gas was supplied as a gate gas to each gas gate. In this state, adjust the exhaust capacity of the vacuum exhaust system,
The pressure in the vacuum chambers 211 to 219 for semiconductor formation was adjusted to a predetermined pressure. The forming conditions are as shown in Table 7.

When the pressure in the semiconductor forming vacuum containers 211 to 219 was stabilized, the movement of the conductive substrate 204 in the direction from the substrate sending container 202 to the substrate winding container 203 was started.

Next, semiconductor forming vacuum vessels 211 to 21
9, high-frequency power sources 251 to 249
To 259, the vacuum chamber 2 for semiconductor formation
Glow discharge is generated in the deposition chambers 11 to 219 to form an amorphous n-type semiconductor layer (thickness: 3) on the conductive substrate 204.
0 nm), amorphous i-type semiconductor layer (film thickness 100 n)
m), microcrystalline p-type semiconductor layer (thickness 10 nm), amorphous n-type semiconductor layer (thickness 30 nm), amorphous i-type semiconductor layer (thickness 100 nm), microcrystalline p-type semiconductor layer (thickness 10 nm), amorphous n-type semiconductor layer (thickness: 30 n)
m), the amorphous i-type semiconductor layer (film thickness 150 n)
m), a microcrystalline p-type semiconductor layer (10 nm thick) was formed to form a photovoltaic element. Here, the semiconductor forming vacuum vessels 211, 214, and 217 have a frequency of 13.56 MHz,
High-frequency power having a power density of 5 W / cm ³ is supplied from high-frequency introduction sections 241, 244, and 247 made of metal electrodes made of Al.
In the semiconductor forming vacuum vessels 212, 215, and 218, the distance between the conductive substrate and the high-frequency introducing section is set to 5 mm, and a high-frequency power of 100 MHz and a power density of 12
While adjusting to 0 mW / cm ³ , a frequency of 13.56 MHz and a power density of 30 mW / cm are supplied from the high-frequency introducing sections 242, 245, 248 made of Al metal electrodes to the vacuum vessels 213, 216, 219 for semiconductor formation. ^Three
Of high-frequency power was introduced from high-frequency introducing sections 243, 246, and 249 made of Al metal electrodes. Here, the residence time τ when forming each i-type semiconductor layer is 0.50 from the substrate side.
Seconds, 0.50 seconds and 0.52 seconds. Next, the formed strip-shaped photovoltaic element was processed into a solar cell module of 36 cm × 22 cm using a continuous modularization device (not shown).

The photoelectric conversion efficiency of the solar cell module prepared as described above was measured using a solar simulator (AM).
(1.5, 100 mW / cm ² ), the photoelectric conversion efficiency was 1.3 compared to the single solar cell module having a residence time of 1.0 second in Example 3.
And the photodegradation rate could be suppressed to 0.7 times. Also, good results were obtained in the peeling test and the temperature / humidity test, and it is understood that the solar cell module including the photovoltaic element of the present invention has excellent features.

Example 5 The photovoltaic element shown in FIG. 6 was formed by the following procedure using the deposited film forming apparatus 201 shown in FIG. FIG. 6 is a schematic sectional view showing an example of a photovoltaic device having a silicon-based thin film of the present invention. In the figure,
The same members as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. The semiconductor layer of this photovoltaic element includes an amorphous n-type semiconductor layer 102-1A and a microcrystalline i-type semiconductor 102-2B.
And the microcrystalline p-type semiconductor layer 102-3A.
That is, this photovoltaic element is a so-called pin type single cell photovoltaic element.

As in the first embodiment, the strip-shaped conductive substrate 20
4 is mounted on the deposition film forming apparatus 201, and the substrate sending container 202, the semiconductor forming vacuum containers 211 and 21 are prepared.
2, 213, 214, 215, 216, 217, 21
8, 219 The substrate take-up container 203 is evacuated to 6.7 × 10 ⁻⁴ Pa (5
(× 10 ⁻⁶ Torr) or less.

Next, while operating the vacuum evacuation system, the gas introduction pipe 2 was introduced into the vacuum chambers 217, 218, and 219 for semiconductor formation.
Source gas and dilution gas were supplied from 37, 238, and 239. Here, the discharge chamber in the semiconductor formation vacuum vessel 218 used had a length of 1 m in the longitudinal direction and a width of 50 cm. Further, the vacuum chambers 217, 218, 2
The vacuum vessel for semiconductor formation other than 19 is
An H ₂ gas of 00 cm ³ / min (normal) was supplied, and at the same time, an H ₂ gas of 500 sccm was supplied as a gate gas from each gate gas supply pipe (not shown) to each gas gate. In this state, adjust the exhaust capacity of the vacuum exhaust system,
The pressure inside the semiconductor formation vacuum containers 217, 218, and 219 was adjusted to a predetermined pressure. The forming conditions are as shown in Table 8.

Semiconductor-forming vacuum vessels 217, 218, 2
When the pressure in the substrate 19 is stabilized, the substrate delivery container 2
The movement of the conductive substrate 204 in the direction from 02 to the substrate take-up container 203 was started.

Next, semiconductor forming vacuum vessels 217 to 21
9, high-frequency power sources 257 to 249
To 259, the vacuum chamber 2 for semiconductor formation
Glow discharge is generated in the deposition chambers 17 to 219, and an amorphous n-type semiconductor layer (thickness: 3) is formed on the conductive substrate 204.
0 nm), a microcrystalline i-type semiconductor layer (thickness: 1.5 μm), and a microcrystalline p-type semiconductor layer (thickness: 10 nm) to form a photovoltaic element. Here, the semiconductor forming vacuum vessel 217 has a frequency of 13.56 MHz and a power density of 5 mW / cm ^3.
The high-frequency power from the high-frequency introducing section 247 made of a metal electrode made of Al, the distance between the conductive substrate and the high-frequency introducing section in the semiconductor forming vacuum vessel 218 is set to 10 mm, and a high frequency of 100 MHz is applied. Power density 40
From the high frequency introduction part 248 composed of a metal electrode made of Al while adjusted to 0 mW / cm ^3, frequency 13.56MHz the semiconductor forming vacuum chamber 219, the RF power density 30 mW / cm ³ containing Al It was introduced from a high-frequency introduction part 249 made of a metal electrode. Next, the formed strip-shaped photovoltaic element was processed into a solar cell module of 36 cm × 22 cm using a continuous modularization device (not shown). The above operation was performed with the pressure in the semiconductor forming vacuum vessel 218 at each residence time shown in Table 9. At that time, the flow rate of the source gas introduced into the semiconductor formation vacuum vessel 218 was adjusted so as to realize each residence time, and further adjusted so that the ratio of SiH ₄ to H ₂ was 1:50. .

The photoelectric conversion efficiency of the solar cell module prepared as described above was measured using a solar simulator (AM).
1.5, 100 mW / cm ² ). Further, the adhesiveness between the conductive substrate and the semiconductor layer was examined by using a cross-cut tape method (interval between cuts 1 mm, number of squares 100). A solar cell module whose initial photoelectric conversion efficiency has been measured in advance is used at a temperature of 85 ° C. and a humidity of 85%.
In a dark place for 30 minutes and then 70 minutes
Lower the temperature to 20 ° C and hold for 30 minutes.
After this cycle of returning the temperature to 85 ° C. and the humidity of 85% was repeated 100 times, the photoelectric conversion efficiency was measured again, and the change in the photoelectric conversion efficiency by the temperature and humidity test was examined. A sample in which only the microcrystalline i-type semiconductor layer was deposited was prepared, and the Scherrer radius was determined from the orientation of (220) and the diffraction pattern of (220) reflection using an X-ray diffraction method. Table 9 shows these results.
Shown in

From Table 9, it can be seen that the solar cell module including a photovoltaic element manufactured with a residence time in the semiconductor formation container 218 of 0.01 seconds or more and 10 seconds or less has a high (220) orientation and a large Scherrer radius. Large, photoelectric conversion efficiency,
Excellent in peeling test, temperature and humidity test items, especially solar cell modules including photovoltaic elements manufactured in 0.1 seconds or more and 3.0 seconds or less have excellent characteristics in peeling test. I understand.

(Example 6) The photovoltaic element shown in FIG. 7 was formed by the following procedure using the deposited film forming apparatus 201 shown in FIG. FIG. 7 is a schematic cross-sectional view illustrating an example of a photovoltaic device having a silicon-based thin film according to an embodiment of the present invention. In the figure, the same members as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. The semiconductor layers of this photovoltaic element include amorphous n-type semiconductor layers 102-1A and 102-7, a microcrystalline i-type semiconductor 102-2B, an amorphous i-type semiconductor layer 102-8, and a microcrystalline p-type semiconductor layer 102-3A. , 10
2-9.

That is, this photovoltaic element has a so-called p
It is an inpin type double cell photovoltaic element.

As in the first embodiment, the belt-shaped conductive substrate 20
4 is mounted on the deposition film forming apparatus 201, and the substrate sending container 202, the semiconductor forming vacuum containers 211 and 21 are prepared.
2, 213, 214, 215, 216, 217, 21
8, 219 The substrate take-up container 203 is evacuated to 6.7 × 10 ⁻⁴ Pa (5
(× 10 ⁻⁶ Torr) or less.

Next, while operating the vacuum evacuation system, the gas introduction pipes 231-2 are introduced into the semiconductor formation vacuum vessels 211-216.
From 36, the raw material gas and the dilution gas were supplied. Here, the discharge chamber in the vacuum chambers 212 and 215 for semiconductor formation used had a length of 1 m in the longitudinal direction and a width of 50 cm. Further, from each gate gas supply pipe (not shown), 500 sccm of H ₂ gas was supplied as a gate gas to each gas gate. In this state, the evacuation capacity of the evacuation system was adjusted to adjust the pressure in the semiconductor formation vacuum vessels 211 to 216 to a predetermined pressure. The forming conditions are as shown in Table 10.

When the pressure in the semiconductor forming vacuum containers 211 to 216 was stabilized, the movement of the conductive substrate 204 in the direction from the substrate sending container 202 to the substrate take-up container 203 was started.

Next, semiconductor forming vacuum vessels 211 to 21
6, high-frequency power supplies 251 to 246
-256 is introduced into the vacuum chamber 2 for semiconductor formation.
Glow discharge is generated in the deposition chambers 11 to 216, and an amorphous n-type semiconductor layer (thickness: 3) is formed on the conductive substrate 204.
0 nm), microcrystalline i-type semiconductor layer (2.0 μm thickness), microcrystalline p-type semiconductor layer (10 nm thickness), amorphous n-type semiconductor layer (30 nm thickness), amorphous i-type semiconductor layer (300 nm thickness) , Microcrystalline p-type semiconductor layer (film thickness 10n)
m) to form a photovoltaic element. Here, the semiconductor forming vacuum vessels 211 and 214 have a frequency of 13.56M.
Hz, a high-frequency power having a power density of 5 mW / cm ³ is supplied to a high-frequency introducing section 241, 244, 24 made of an Al metal electrode.
7, the distance between the conductive substrate and the high-frequency introduction part was set to 10 mm in the semiconductor forming vacuum vessel 212, a high frequency of 100 MHz was applied, and the power density was 400 mW.
/ Cm ³ , the distance between the conductive substrate and the high-frequency introducing section is set to 5 mm from the high-frequency introducing section 242 made of an Al metal electrode to the semiconductor-forming vacuum vessel 215 while adjusting to 5 mm / cm ³ . While adjusting the high frequency of the frequency of 100 MHz so that the power density becomes 100 mW / cm ³ , from the high frequency introducing portion 245 made of an Al metal electrode,
The frequency 13.2 is set in the vacuum chambers 213 and 216 for semiconductor formation.
The high frequency power of 56 MHz and the power density of 30 mW / cm ³ is supplied to the electric frequency introducing parts 243 and 24 made of Al metal electrodes.
6 introduced. Here, the residence time τ at the time of forming each i-type semiconductor layer was 0.50 seconds and 0.52 seconds from the substrate side. Next, the formed strip-shaped photovoltaic element was processed into a solar cell module of 36 cm × 22 cm using a continuous modularization device (not shown).

The photoelectric conversion efficiency of the solar cell module prepared as described above was measured using a solar simulator (AM).
1.5, 100 mW / cm ² ), the value of the photoelectric conversion efficiency was 1.2 compared to the single solar cell module having a residence time of 1.0 second in Example 5.
Doubled. Also, good results were obtained in the peeling test and the temperature / humidity test. From the above, it can be seen that the solar cell module including the photovoltaic element of the present invention has excellent features.

[0103]

According to the present invention, it is possible to form a silicon-based thin film having excellent characteristics with a low defect density at a higher speed, and the silicon-based thin film is formed on a substrate by at least one set of pin junctions. By using at least a part of at least one i-type semiconductor layer of a photovoltaic element including a semiconductor layer comprising, a photovoltaic element having good photoelectric conversion efficiency, excellent adhesion, and excellent environmental resistance. , And can be formed at low cost.

[0104]

[Table 1]

[0105]

[Table 2] The photoelectric conversion efficiency is determined by the distance 3 between the conductive substrate and the high-frequency introduction part.
The value obtained by normalizing the value at mm to 1.

[0106]

[Table 3]

[0107]

[Table 4] Photoelectric conversion efficiency: A value obtained by normalizing the value when the pressure in the semiconductor forming container 218 is 50 Pa to 1 Peeling test: Number of peeled squares ：: 0, ：: 1-2, Δ: 3 to 10, ×: 10 to 100 Temperature / humidity test: Value of (photoelectric conversion efficiency after test) / (photoelectric conversion efficiency before test) Light deterioration rate: The light deterioration rate when the pressure in semiconductor forming container 218 is 50 Pa is 1 Standardized value

[0108]

[Table 5]

[0109]

[Table 6] Photoelectric conversion efficiency: Value obtained by standardizing the value when the residence time in the semiconductor forming container 218 is 0.08 seconds to 1 Peeling test: Number of peeled squares ：: 0, ○ 1-2, △: 3 ~ 10, ×: 10 to 100 Temperature / humidity test: value of (photoelectric conversion efficiency after test) / (photoelectric conversion efficiency before test) Photodegradation rate: when residence time in semiconductor formation container 218 is 0.008 seconds Light degradation rate normalized to 1

[0110]

[Table 7]

[0111]

[Table 8]

[0112]

[Table 9] Scherrer radius: a value obtained by normalizing the value when the residence time in the semiconductor formation container 218 is 0.008 seconds to 1 Photoelectric conversion efficiency: a value when the residence time in the semiconductor formation container 218 is 0.008 seconds Peeling test: The number of peeled squares ◎: 0, ○ 1-2, △: 3-10, ×: 10-100 Temperature / humidity test: (photoelectric conversion efficiency after test) / (test Value of previous photoelectric conversion efficiency)

[0113]

[Table 10]

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view illustrating an example of a photovoltaic device according to an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view showing an example of a deposited film forming apparatus for manufacturing a silicon-based thin film and a photovoltaic element according to an embodiment of the present invention.

FIG. 3 is a schematic cross-sectional view illustrating an example of a semiconductor layer according to an embodiment of the present invention.

FIG. 4 is a schematic cross-sectional view showing an example of a photovoltaic device including a silicon-based thin film according to an embodiment of the present invention.

FIG. 5 is a schematic cross-sectional view showing an example of a photovoltaic element including a silicon-based thin film according to an embodiment of the present invention.

FIG. 6 is a schematic cross-sectional view showing an example of a photovoltaic device including a silicon-based thin film according to an embodiment of the present invention.

FIG. 7 is a schematic sectional view showing an example of a photovoltaic device having a silicon-based thin film according to an embodiment of the present invention.

[Explanation of symbols]

 101: Substrate 101-1: Base 101-2: Metal Layer 101-3: First Transparent Conductive Layer 102: Semiconductor Layer 102-1: Semiconductor Layer Showing First Conductive Type 102-1A: Amorphous n-Type Semiconductor Layer 102-2: i-type semiconductor layer 102-2A: amorphous i-type semiconductor layer 102-2B: microcrystalline i-type semiconductor layer 102-3: semiconductor layer showing the second conductivity type 102-3A: microcrystalline p-type semiconductor layer 102-4: amorphous n-type semiconductor layer 102-5: amorphous i-type semiconductor layer 102-6: microcrystalline p-type semiconductor layer 102-7: amorphous n-type semiconductor layer 102-8: amorphous i-type semiconductor layer 102-9: Microcrystalline p-type semiconductor layer 103: Transparent electrode 104: Current collecting electrode 20: Deposited film forming apparatus 202: Substrate sending container 203: Substrate winding container 204: Conductive group 211 to 219: semiconductor forming vacuum chambers 221 - 230: gas gates 231 to 239: gas introduction pipe 241 to 249: high-frequency power supply unit 251 to 259: high frequency power source

Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H01L 31/04 W 31/10 A (72) Inventor Koichiro Moriyama 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon stock In-house (72) Inventor Kenshi Shishido 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Takahiro Yajima 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term in Canon Inc. (Reference) 4K030 AA06 BA01 BA29 BB04 FA01 JA03 JA05 JA09 KA30 LA16 5F049 MA01 MB04 MB05 NA01 NA20 PA03 PA18 5F051 AA04 AA05 BA14 CA16 CA22 CA34 DA04 DA17

Claims (21)

[Claims] A method of forming a silicon-based thin film on a substrate introduced into a vacuum vessel by using a high-frequency plasma CVD method by introducing a raw material gas into the vacuum vessel, wherein a discharge in which plasma is generated is provided. A part of the space is covered by at least a part of the substrate, the high-frequency introduction unit and the substrate face each other, and a distance between the high-frequency introduction unit and the substrate is 3
mm to 30 mm, and the pressure in the discharge space is 90 mm or more.
Pa (0.68 Torr) or more and 1.5 × 10 ⁴ Pa (1
13 Torr) or less, the volume of the discharge space in which the plasma is generated is V (m ³ ), the flow rate of the raw material gas is Q (cm ³ / min (normal)), and the pressure of the discharge space is P (Pa). Τ = 592 × V × P / Q
Wherein the residence time τ defined by the formula (1) is 0.01 seconds or more and 10 seconds or less. 2. The method for forming a silicon-based thin film according to claim 1, wherein said source gas comprises a mixed gas containing a silicon hydride compound and hydrogen. 3. The method for forming a silicon-based thin film according to claim 2, wherein said source gas contains a germanium hydride compound. 4. The method for forming a silicon-based thin film according to claim 2, wherein the flow rate of hydrogen relative to the silicon hydride compound in the source gas is 30 times or more. 5. The method for forming a silicon-based thin film according to claim 2, wherein the input power of the high frequency is A (W), and the product of the area of the high frequency introduction section and the distance between the high frequency introduction section and the substrate is B (cm ³ ).
The value of the high frequency density A / B is 0.05 to 2 W
/ Cm ³ , a method for forming a silicon-based thin film. 6. A method for introducing a raw material gas into a vacuum vessel and forming a silicon-based thin film on a substrate introduced into the vacuum vessel by using a high-frequency plasma CVD method, wherein a discharge space where plasma is generated is formed. A part is covered by at least a part of the substrate, the high-frequency introduction unit and the substrate face each other, and a distance between the high-frequency introduction unit and the substrate is 3
mm to 30 mm, and the pressure in the discharge space is 90 mm or more.
Pa (0.68 Torr) or more and 1.5 × 10 ⁴ Pa (1
13 Torr) or less, the volume of the discharge space in which the plasma is generated is V (m ³ ), the flow rate of the raw material gas is Q (cm ³ / min (normal)), and the pressure of the discharge space is P (Pa). Τ = 592 × V × P / Q
A silicon-based thin film formed so that the residence time τ defined by the formula is 0.01 seconds or more and 10 seconds or less. 7. The silicon-based thin film according to claim 6, wherein said source gas comprises a mixed gas containing a silicon hydride compound and hydrogen. 8. The silicon-based thin film according to claim 7, wherein said source gas contains a germanium hydride compound, and said silicon-based thin film is made of an alloy of silicon and germanium. 9. The silicon-based thin film according to claim 7, wherein
A silicon-based thin film including a microcrystal having a crystal diameter of 20 nm or more in a cherr radius. 10. The silicon-based thin film according to claim 9,
A silicon-based thin film, wherein the flow rate of hydrogen in the raw material gas with respect to the hydrogenated silicon compound is 30 times or more. 11. The silicon-based thin film according to claim 9, wherein the silicon-based thin film has a Raman scattering intensity due to a crystalline component that is three times or more as large as a Raman scattering intensity due to an amorphous component. Silicon based thin film. 12. The silicon-based thin film according to claim 9, wherein the silicon-based thin film has a ratio of diffraction intensity of (220) by X-ray or electron beam diffraction of 70% or more with respect to the total diffraction intensity. Characterized silicon thin film. 13. The silicon-based thin film according to claim 9, wherein a high-frequency introduction power is A (W), and a product of a high-frequency introduction section area and a distance between the high-frequency introduction section and the substrate is B (cm ³ ). Of the high frequency density A / B of 0.05 to 2 W /
cm. ³ , a silicon-based thin film. 14. At least one i-type semiconductor layer of a photovoltaic element including a semiconductor layer comprising at least one set of pin junctions on a substrate introduces a source gas into a vacuum vessel,
High frequency plasma CV is applied on the substrate introduced into the vacuum vessel.
In a method of forming a silicon-based thin film using the D method,
A part of the discharge space where plasma is generated is covered by at least a part of the substrate, the high-frequency introduction unit and the substrate are opposed to each other, and the distance between the high-frequency introduction unit and the substrate is 3 mm or more. 30 mm or less, and the pressure in the discharge space is 90 Pa (0.68 Torr) or more and 1.5 × 10 ⁴ P
a (113 Torr) or less, the volume of the discharge space in which the plasma is generated is V (m ³ ), the flow rate of the raw material gas is Q (cm ³ / min (normal)), and the pressure of the discharge space is P ( Pa), τ = 592 × V ×
The residence time τ defined by P / Q is 0.01 second or more and 10
A photovoltaic element comprising a silicon-based thin film formed by a method for forming a silicon-based thin film, wherein the time is not more than seconds. 15. The photovoltaic device according to claim 14, wherein said source gas is a mixed gas containing a silicon hydride compound and hydrogen. 16. The photovoltaic device according to claim 15, wherein said source gas contains a germanium hydride compound, and said silicon-based thin film is made of an alloy of silicon and germanium. . 17. The photovoltaic device according to claim 15, wherein the silicon-based thin film has a Scherrer radius of 2
A photovoltaic element comprising a silicon-based thin film containing microcrystals having a crystal grain size of 0 nm or more. 18. The photovoltaic device according to claim 17, wherein the flow rate of hydrogen to the silicon hydride compound in the source gas is 30 times or more. 19. The photovoltaic device according to claim 17, wherein the silicon-based thin film has a Raman scattering intensity due to a crystalline component that is three times or more as large as a Raman scattering intensity due to an amorphous component. Photovoltaic element. 20. The photovoltaic device according to claim 17, wherein in the silicon-based thin film, the ratio of the diffraction intensity of (220) by X-ray or electron diffraction is 70% or more with respect to the total folding intensity. A photovoltaic element characterized by the above-mentioned. 21. The photovoltaic device according to claim 17, wherein the introduced power of the high-frequency wave is A (W), and the product of the area of the high-frequency wave introduction section and the distance between the high-frequency wave introduction section and the substrate is B (cm ³ ). When the value of the high frequency density A / B is 0.05 to 2 W /
cm. ³ is a silicon-based thin film.