JPH11243223A - Electrolytic precipitation bath, method and device for depositing oxide thin film, photovoltaic element using the same and method for manufacturing the same, and manufacture of semiconductor element substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a zinc oxide thin-film deposition device, wherein through the use electrolytic precipitation method, a zinc oxide thin-film is deposited evenly and stably over the entire surface of a conductive base body. SOLUTION: The deposition device comprises an electrolytic precipitation bath 103 in which a conductive base body 110 and a counter electrode 111 are electrified in a water solution to form an oxide thin-film on the base body 110, rinsing means 104 and 105 for rinsing in water the base body 110 which passes it, and a drying means 107 for forcedly drying the base body 110 passing it. Here, a conductive member 109a, which makes contact with the rear surface of the base body 110 for supplying power, is provided with a liquid supplying means 109b which supplies water or water solution to its surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolytic deposition tank for forming an oxide thin film on a substrate by energizing a conductive substrate and an electrode in an aqueous solution, an apparatus and a method for depositing an oxide thin film,
The present invention relates to a photovoltaic element and a manufacturing method using the same, and a method for manufacturing a semiconductor element substrate.

[0002]

2. Description of the Related Art Conventionally, a photovoltaic element made of hydrogenated amorphous silicon, hydrogenated amorphous silicon germanium, hydrogenated amorphous silicon carbide or microcrystalline silicon has a low collection efficiency at a long wavelength. In order to improve, a back reflection layer is provided. This reflective layer is near the band edge of the semiconductor material and has a wavelength at which its absorption is reduced, ie, 800 n.
It is desirable to exhibit effective reflection characteristics at wavelengths from m to 1200 nm. Satisfying this condition enough is
It is a layer of a metal such as gold, silver, copper, or aluminum.

[0003] An optically transparent concavo-convex layer is also provided in a predetermined wavelength range known as light confinement. Generally, the concavo-convex layer is provided between the metal layer and the semiconductor layer. Is provided to improve the short-circuit current density Jsc by effectively using the reflection layer.

Further, in order to prevent deterioration in characteristics due to a shunt path, a layer made of a light-transmitting material having conductivity, that is, a transparent conductive layer is provided between the metal layer and the semiconductor layer. Very commonly, these layers are deposited by methods such as vacuum evaporation or sputtering,
It shows an improvement of 1 mA / cm ² or more in short-circuit current density Jsc.

[0005] As an example, Prior Art 1: "29p-M
Light Confinement Effect in a-SiGe Solar Cell on F-22 Stainless Steel Substrate "(Fall 1990) 51st Annual Meeting of the Japan Society of Applied Physics p747, Prior Art 2:" P-IA
-15a-SiC / a-Si / a-SiGe Multi
i-Bandgap, Stacked, Solar, C
wells ・ With ・ Bandgap ・ Profili
ng "Sannomiya et al., Techni
cal ・ Digest ・ of ・ the ・ Interna
Tional / PVSEC-5, Kyoto, Japan
n, p381, 1990, etc., the reflectance and texture structure of a reflective layer composed of silver atoms have been studied.

In these examples, effective unevenness is formed by changing the substrate temperature to form two reflective layers in which silver is deposited, and thus the light is confined by the light confinement effect in combination with the zinc oxide layer. An increase in short-circuit current has been achieved.

[0007]

Conventionally, a transparent conductive layer used as a light confinement layer has been deposited by a vacuum deposition method using resistance heating or an electron beam, a sputtering method, an ion plating method, a CVD method, or the like. ,
The high cost of making target materials, the high cost of depreciation of vacuum equipment, and the low efficiency of material utilization make the cost of photovoltaic devices using these technologies extremely high. Has become a major barrier to industrial application.

As one of these countermeasures, zinc oxide production technology by liquid phase deposition method (prior art 3: “Preparation of ZnO film by aqueous solution electrolysis” (Autumn 1995)) Proceedings of the 65th Annual Conference of the Japan Society of Applied Physics p410 has been reported.

According to these methods, expensive vacuum equipment and targets are not required, so that the production cost of zinc oxide can be drastically reduced. Further, since it can be deposited on a large area substrate, it is promising for a photovoltaic element having a large area like a solar cell. However, there are the following problems in continuously depositing a zinc oxide thin film on a long conductive substrate using these electrochemical methods.

That is, the electrical contact between the conductive member serving as one of the electrodes and the back surface of the long conductive substrate may be insufficient, and the voltage may drop. There has been a problem that a zinc oxide thin film cannot be uniformly and stably deposited over the entire surface of the substrate.

Particularly, when a zinc oxide thin film is formed on a long conductive substrate at a high temperature for a long time, the position where the conductive member comes into contact with the conductive substrate and the conductive substrate is immersed in an aqueous solution. There is a problem that the surface of the substrate is dried and unevenness may occur between the positions. In addition, when drying, a white film is slightly deposited, which may be conveyed into the aqueous solution to contaminate the liquid. Furthermore, water vapor may condense and dry on the substrate,
There is a problem that unevenness may occur on the substrate surface.

These irregularities and stains of the solution may cause abnormal growth in the zinc oxide thin film in the form of needles, spheres, dendrites or the like exceeding micron order.
When this zinc oxide thin film is used as a part of a photovoltaic element, unevenness or abnormal growth on the substrate surface causes a shunt path of the photovoltaic element.

The present invention provides an apparatus for depositing a zinc oxide thin film capable of uniformly and stably depositing a zinc oxide thin film over the entire surface of a long conductive substrate by using an electrolytic deposition method which is a low cost technique. And a deposition method, and incorporating this zinc oxide thin film into the process of forming a photovoltaic device, thereby providing a photovoltaic device having excellent mass productivity, low cost, and high performance, and a method for manufacturing the photovoltaic device. It is another object of the present invention to provide a method for manufacturing a semiconductor element substrate that can contribute to the full-scale spread of photovoltaic power generation.

[0014]

Means for Solving the Problems The inventions of claims 1 to 7 are:
The present invention relates to an electrolytic deposition tank for forming an oxide thin film on a substrate by energizing a conductive substrate and an electrode in an aqueous solution. Another feature is that a liquid supply means for supplying an aqueous solution is provided.

The invention of claims 8 to 14 provides an electrolytic deposition tank for forming an oxide thin film on a substrate by supplying a current to a conductive substrate and an electrode in an aqueous solution, and rinsing the substrate passing therethrough with water. The present invention relates to a device for depositing an oxide thin film, comprising: a washing unit that performs washing, and a drying unit that forcibly dry a substrate that has passed therethrough.
It is characterized in that a liquid supply means for supplying water or an aqueous solution is provided on its surface.

Further, the invention according to claims 15 to 21 is characterized in that a conductive substrate immersed in an aqueous solution containing at least nitrate ions, zinc ions and carbohydrates, and an electrode immersed in the solution. In the method of depositing an oxide thin film for forming an oxide thin film on a substrate by applying a current,
It is characterized in that electricity is supplied while water or an aqueous solution is supplied to the surface of a conductive member that supplies power by contacting the back surface of the base.

Further, the invention of claim 22 relates to a photovoltaic element, and is characterized in that the oxide thin film formed by the deposition method of any one of claims 15 to 21 is provided as a transparent conductive layer. .

Further, the invention according to claims 23 to 29 is characterized in that a conductive substrate immersed in an aqueous solution containing at least nitrate ions, zinc ions and carbohydrates, and an electrode immersed in the solution. The present invention relates to a method for manufacturing a photovoltaic element including a step of forming an oxide thin film on a substrate by applying a current, and a step of forming a semiconductor layer,
It is characterized in that an oxide thin film is formed by supplying electricity while supplying water or an aqueous solution to the surface of the conductive member which is in contact with the back surface of the base and supplies power.

The invention according to claims 30 to 36 is characterized in that a conductive substrate immersed in an aqueous solution containing at least nitrate ions, zinc ions and carbohydrates and an electrode immersed in the solution are provided. The present invention relates to a method for manufacturing a semiconductor element substrate in which an oxide thin film is formed on a base by applying an electric current. It has features.

As described above, the present invention relates to a novel electrolytic deposition tank, an apparatus and a method for depositing an oxide thin film, a photovoltaic element and a manufacturing method using the same, and the constitution and operation of each invention. This will be further described below.

1) Electricity is supplied while water or an aqueous solution is supplied to the surface of the conductive member that supplies power by contacting the back surface of the conductive substrate. Thereby, the electrical contact between the conductive member serving as one electrode and the back surface of the conductive base becomes sufficient, and the voltage does not drop, and the length direction of the conductive base,
An oxide thin film can be deposited uniformly and stably over the entire surface in the width direction.

2) The aqueous solution supplied from the liquid supply means is
By containing at least nitrate ions, electrical conduction is promoted.

3) Water supply means for supplying water to both surfaces of the substrate is provided between a position where the conductive member contacts the substrate and a position where the substrate is immersed in the aqueous solution. This, in particular,
When forming a zinc oxide thin film on a long conductive substrate for a long time at a high temperature, drying of the conductive substrate is avoided,
An oxide thin film can be deposited on the surface of the conductive substrate without generating unevenness or abnormal growth.

4) Since the conductive member is formed as a feeding roller, electrical contact can be made relatively easily, and excellent uniformity of mass production of a uniform oxide thin film is obtained.

5) Since the conductive substrate is a conductive substrate having a zinc oxide thin film previously deposited on its deposition surface, it is relatively easy to deposit a zinc oxide thin film with little abnormal growth efficiently and uniformly. it can.

6) A uniform oxide thin film is formed on the substrate by using a roll-to-roll method in which the conductive substrate is a long substrate and the film is deposited while moving the long substrate stretched between rolls. Can be continuously deposited.

7) A photovoltaic element using an oxide thin film such as a zinc oxide thin film formed in this manner is inexpensive, high in quality (excellent in short-circuit current, conversion efficiency and adhesion) and mass-producible. Is excellent. In particular, the manufacturing cost of the zinc oxide layer can be reduced to about 1/100 as compared with the sputtering method.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below, but the present invention is not limited to these embodiments.

(Zinc Oxide Thin Film Deposition Apparatus) FIG. 1 is a schematic view schematically showing a zinc oxide thin film deposition apparatus of the present invention. As shown in FIG. In FIG. 1, the deposition apparatus of the present invention comprises:
An electrolytic deposition tank 103 composed of a feed roller 101, a power supply chamber 103a, an overflow chamber 103b, and a zinc oxide deposition bath 103c, a shower cleaning tank 104, and a water cleaning tank 10.
5, an air knife 106, a drying heater 107, a meandering correction roller 108, and a winding roller 102.

In the power supply chamber 103a, a conductive member 109a serving as a cathode when depositing a zinc oxide thin film, the conductive member 1
A shower 109b for spraying an aqueous solution containing at least nitrate ions on the substrate 09a, and a shower 1 for spraying the aqueous solution so that the surface of the substrate 110 is not dried.
09c and 109d are provided.

Further, in the zinc oxide deposition bath 103c,
A counter electrode 111 serving as an anode during deposition of the zinc oxide thin film is provided, and is connected to the DC power supply 112 together with the conductive member 109a. Substrate 110 and / or conductive member 1
09a is electrically grounded.

The aqueous solution containing at least zinc ions and nitrate ions and saccharose or dextrin in the zinc oxide deposition bath 103c is heated to a desired temperature by a preliminary tank (not shown) and is pumped by a pump (not shown). The aqueous solution is circulated and supplied to the zinc oxide deposition bath 103c so that the liquid surface maintains a desired height.

(Method for Depositing a Zinc Oxide Thin Film by Electrodeposition) Next, a method for depositing a zinc oxide thin film of the present invention will be described using, for example, a deposition apparatus shown in FIG. In FIG.
Substrate 110 wound around delivery roller 101
Is transported along the path shown in the drawing, and while correcting a slight displacement of the substrate 110 by the meandering correction roller 108,
It is wound up neatly by the winding roller 102.

The substrate 110 comes into contact with the conductive member 109a in the power supply chamber 103a, and DC power is applied by the DC power supply 112 so that the conductive member 109a serves as a cathode and the counter electrode 111 serves as an anode. At this time, an aqueous solution containing at least nitrate ions is sprayed from the shower 109b in order to further ensure the contact between the conductive member 109a and the substrate 110. The aqueous solution is sprayed from the showers 109c and 109d so that the front and back surfaces of the substrate 110 are not dried.

The conductive member 109a is provided at least on the substrate 1
It is sufficient that the portion in contact with 10 is conductive, for example, stainless steel, a material whose surface is plated with gold, platinum, or the like, a conductive resin in which powder of conductive carbon or the like is dispersed in resin or rubber, and Rubber or the like is used. Also, the shape of the conductive member 109a is not particularly limited, and for example, a rod-shaped member, a roller, or the like is used. When a roller is used, the roller may be driven to rotate in synchronization with the substrate transport speed.

The aqueous solution sprayed from the shower 109b has a nitrate ion concentration of 0.004 mol / l to 6.0.
mol / l, preferably 0.01 mol / l to 1.5 m
ol / l, more preferably 0.1 mol / l to 1.4.
mol / l. As this aqueous solution, the same aqueous solution as an electrolytic deposition aqueous solution described later may be adopted. In this case, the drainage path of the power supply chamber 103a is directly returned to the spare tank (not shown) and circulated, so that the electrolytic deposition aqueous solution can be used efficiently.

As the aqueous solution sprayed from the showers 109c and 109d, any solution may be sprayed as long as both surfaces of the long conductive substrate are not dried. However, in order to avoid contamination of impurities,
It is preferable to use pure water, an aqueous solution containing at least nitrate ions, the same aqueous solution as an electrolytic deposition aqueous solution described later, or the like.
In the case where the same aqueous solution as the electrolytic deposition aqueous solution to be described later is employed, the drainage path of the power supply chamber 103a and the overflow chamber 1
There is no need to separate the drain passage 03b from the drainage passage, and by circulating the wastewater back to the preliminary tank (not shown), the electrolytic deposition aqueous solution can be used efficiently.

Further, as shown in FIG.
In a device in which the zinc oxide deposition bath 103c and the zinc oxide deposition bath 103c are integrally formed, particularly when forming a zinc oxide thin film on a long conductive substrate at a high temperature for a long time, the shower 109 is used.
It is important to spray an aqueous solution from c and d onto the substrate to prevent the surface from drying. This is because drying may cause unevenness on the substrate surface.

Also, when drying, a slightly white film is deposited, which may be transported into the aqueous solution to contaminate the liquid. Further, water vapor may condense and dry while remaining on the substrate, which may cause unevenness.

These irregularities and stains of the solution may cause abnormal growth in the form of needles, spheres, dendrites, etc. exceeding the micron order during deposition of the zinc oxide thin film. When used as a part of a photovoltaic element, unevenness or abnormal growth on the substrate surface causes a shunt path of the photovoltaic element.

The zinc oxide deposition bath 103c contains an electrolytic deposition aqueous solution containing at least nitrate ions, zinc ions, saccharose, or dextrin. The zinc ion concentration of this aqueous solution of electrolytic deposition was 0.002 mol /
1 to 3.0 mol / l, preferably 0.01 mol / l
~ 1.5 mol / l, more preferably 0.05 mol
/ L to 0.7 mol / l.

The nitrate ion concentration is 0.004 mol
1 / l to 6.0 mol / l, preferably 0.01 mol
/ L to 1.5 mol / l, more preferably 0.1 mol
1 / l to 1.4 mol / l.

Further, the concentration of saccharose was 1 g / l.
~ 500g / l, more preferably 3g / l ~ 100g
/ L, and the concentration of dextrin is from 0.01 g / l to
10 g / l, more preferably 0.025 g / l to 1 g
/ L.

By adjusting the concentration of the electrolytic deposition aqueous solution in this way, a zinc oxide thin film having a texture structure suitable for a light confinement effect can be efficiently deposited.

The DC power supply 112 is controlled so that a constant current flows. The current here is 0.1 mA / cm ²
１００100 mA / cm ² , preferably 1 mA / cm ² ３０30
mA / cm ² , more preferably 3 mA / cm ^{2 to} 15 m
A / cm ² . By setting the solution temperature at 50 ° C. or higher, a uniform zinc oxide thin film with little abnormal growth can be efficiently deposited.

FIG. 2 is a schematic view schematically showing the cross-sectional structure of the photovoltaic device of the present invention having the zinc oxide thin film thus deposited. 2, reference numeral 201 denotes a support, 202 denotes a metal layer, 203 denotes a transparent conductive layer of zinc oxide made of hexagonal polycrystal, 204 denotes a semiconductor layer, 205 denotes a transparent electrode, and 206 denotes a current collecting electrode.

The support 201 and the metal layer 202 form the light-reflective metal substrate according to the present invention. In the case where light is incident from the transparent substrate side, each layer is formed in reverse order except for the substrate.

Next, each component of the photovoltaic element of the present invention will be described.

(Substrate) As the substrate 201, a metal plate such as a stainless steel plate, a steel plate, a copper plate, a brass plate, an aluminum plate, or a resin, a glass, a ceramic, or the like coated with a conductive material is used. The surface of the substrate may have fine irregularities. A structure may be employed in which light is incident from the substrate side using a transparent substrate.

Further, by forming the base into a long sheet-like shape, the base can be wound in a coil shape, so that it is possible to cope with continuous film formation, and storage and transportation are facilitated. In particular, stainless steel, polyimide, and the like are preferable because they have flexibility.

(Metal Layer) The metal layer 202 has a role as an electrode and a role as a reflection layer that reflects light reaching the base and reuses it in the semiconductor layer. Al, Cu, A
g, Au and the like are formed by a method such as an evaporation method, a sputtering method, an electrolytic deposition method, and printing.

By having irregularities on the surface of the metal layer,
This has the effect of extending the optical path length of the reflected light in the semiconductor layer and increasing the short-circuit current.

If the substrate itself has conductivity, the metal layer need not be formed.

(Transparent Conductive Layer) The transparent conductive layer 203 increases the irregular reflection of incident light and reflected light, and extends the optical path length in the reflective layer. Further, it prevents the elements of the metal layer from diffusing or maggregating into the semiconductor layer, thereby preventing the photovoltaic element from shunting. Further, by having an appropriate resistance, a short circuit due to a defect such as a pinhole in the semiconductor layer is prevented.

Further, it is preferable that the surface of the metal layer has irregularities as in the case of the metal layer. The transparent conductive layer 203 is made of Zn
The conductive oxide such as O or ITO is formed by a method such as an evaporation method, a sputtering method, a CVD method, and an electrolytic deposition method. In the present embodiment, an electrolytic deposition method that is inexpensive in equipment cost and material cost is used.

(Semiconductor Layer) The material of the semiconductor layer is amorphous or microcrystalline Si, C, Ge, or an alloy thereof. At the same time, hydrogen and / or halogen atoms are contained. Its preferred content is 0.1 to
40 atomic%. Further, oxygen, nitrogen and the like may be contained. The concentration of these impurities is preferably 5 × 10 ¹⁹ cm ⁻³ or less. Further, a p-type semiconductor contains a group III element, and an n-type semiconductor contains a group V element.

In the case of a stack cell, pi close to the light incident side
The n-junction i-type semiconductor layer has a wide band gap and
It is preferable that the band gap becomes narrower as the junction becomes in-junction. Further, it is preferable that the band gap has a minimum value closer to the p layer than the center of the film thickness in the i layer.

As the doped layer on the light incident side, a crystalline semiconductor with little light absorption or a semiconductor with a wide band gap is suitable.

To form a semiconductor layer, a microwave (M
W), a plasma CVD method or a radio frequency (RF) CVD method is suitable.

This semiconductor deposition technique is disclosed in
No. 1,184,843 discloses that “i-layer is Grad.
Ge composition of 20 to 70 atm% in ed SiGe "or the like can be used.

(Transparent Electrode) The transparent electrode 207 can also serve as an antireflection film by appropriately setting its film thickness. The transparent electrode 207 is made of ITO, ZnO, I
A material such as nO ₃ is formed by a method such as an evaporation method, a CVD method, a spray method, a spion method, and an immersion method. These compounds may contain a substance that changes electric conductivity.

(Current Collecting Electrode) The current collecting electrode 208 is provided to improve current collecting efficiency. As the formation method,
There are 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, and a method of fixing a metal wire with a conductive paste.

Incidentally, if necessary, protective layers may be formed on both surfaces of the photovoltaic element. At the same time, a reinforcing material such as a steel plate may be used.

[0064]

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

Example 1 In Example 1, a zinc oxide thin film was deposited using the deposition apparatus shown in FIG. That is, a long conductive substrate 110 made of stainless steel (SUS430BA) having a width of 120 mm, a length of 100 m, and a thickness of 0.15 mm is mounted on a delivery roller 101, and the substrate 110 is transported along a path shown in the drawing. 200cm / m
The sheet is conveyed in, and is taken up by the take-up roller 102.

The aqueous solution of electrolytic deposition used for depositing zinc oxide contains 60 g of zinc nitrate hexahydrate and 0.1 g of dextrin in 1 liter of water, and is heated to 53 ° C. in advance in a preliminary tank (not shown). Then, it is circulated and supplied to the electrolytic deposition tank by a pump (not shown). At this time, the liquid temperature of the electrolytic deposition aqueous solution is 5
It is kept at 0 ° C. and the pH is kept between 4.0 and 6.4. This aqueous solution was agitated with air in order to minimize temperature unevenness and concentration unevenness.

As the counter electrode 111 of the anode, zinc whose surface is buffed is used, and for the cathode, a power supply roller having a surface made of stainless steel is used as the conductive member 109a.
A valve (not shown) was adjusted and supplied from the shower 109b so that the same aqueous solution as the electrolytic deposition aqueous solution was uniformly and slightly applied to the entire surface of the power supply roller.

At this time, a current was supplied between the feeding roller and the counter electrode so that a current density of 5.0 mA / cm ² (0.5 A / dm ² ) was kept constant to perform electrolytic deposition. .
Thus, by supplying the aqueous solution slightly to the surface of the power supply roller serving as the cathode, the electrical contact between the power supply roller and the conductive substrate was sufficient, and no voltage drop was observed during electrolytic deposition. In this example, the showers 109c and 109d shown in FIG. 1 were not used.

After that, the long conductive substrate 110 is washed with water in the shower washing tank 104 and the washing tank 105 in this order.
Draining is performed by the air knife 106 and the drying heater 1
At 07, the substrate is wound around the winding roller 102 as a substrate on which the metal layer 202 and the transparent conductive layer 203 of zinc oxide are formed.

The thickness of the zinc oxide thin film thus obtained was uniform at 1.50 ± 0.07 μm over the entire surface of the long conductive substrate in the longitudinal and width directions.

Comparative Example 1 A zinc oxide thin film was deposited in the same manner as in Example 1 except that the supply of the aqueous solution from the shower 109b to the power supply roller was stopped.

When the surface of the substrate was observed after the deposition of the zinc oxide thin film, a portion having a clearly thin film thickness was observed in some places. When measuring the film thickness of this part at several places, 5000、５, 7000Å,
Values such as 1 μm were obtained. In some places, the film thickness was too thin, and the film thickness could not be determined by optical measurement.

In some cases, during the deposition of zinc oxide, the electrical contact between the power supply roller and the conductive substrate becomes insufficient, and the power supply to the substrate becomes insufficient. It is considered that the film thickness was not obtained over the entire surface of the long conductive substrate.

Example 2 In Example 2, a zinc oxide thin film was deposited using the deposition apparatus shown in FIG. In FIG. 3, width 120 mm, length 100 m, thickness 0.15 mm
A long conductive substrate 310 made of stainless steel (SUS430BA) is mounted on the delivery roller 301, and the substrate 310 is transported at a transfer speed of 300 cm / along the illustrated path.
min and is wound up by the take-up roller 302.

The aqueous solution of electrolytic deposition used for depositing zinc oxide contains 65 g of zinc nitrate hexahydrate and 0.2 g of dextrin in one liter of water, and is heated to 75 ° C. in advance in a preliminary tank (not shown). And an electrolytic deposition tank 303 by a pump (not shown).
Circulated and supplied to.

At this time, the temperature of the electrolytic deposition aqueous solution was 72 ° C.
And the pH is maintained between 4.0 and 6.4.
This aqueous solution was agitated with air in order to minimize temperature unevenness and concentration unevenness.

As the counter electrode 311 of the anode, zinc whose surface was buffed was used, and for the cathode, a power supply roller whose surface was made of stainless steel was used as the conductive member 309a. 5.0 mA / cm ² (0. 0 mA) between the feeding roller and the counter electrode.
5A / dm ² ) so that the current density is kept constant.
Electric power was supplied from a C power supply 312 to perform electrolytic deposition.

At this time, an aqueous solution having a nitrate ion concentration of 0.2 mol / l was supplied from the shower 309b by adjusting a valve (not shown) so as to uniformly and slightly apply the aqueous solution. As described above, by supplying the aqueous solution slightly to the surface of the power supply roller serving as the cathode, electrical contact between the power supply roller and the conductive substrate became sufficient, and no voltage drop was observed during electrolytic deposition.

Thereafter, the shower tub 304 and the water tub 3
After washing with water in order at 05, draining is performed with an air knife 306 and dried with a drying heater 307.
2. The substrate is wound around a winding roller 302 as a substrate on which a transparent conductive layer 203 of zinc oxide is formed. The thickness of the zinc oxide thin film thus obtained was 1.70 ± 0.0 over the entire length and width directions of the long conductive substrate.
It was uniform at 8 μm.

In FIG. 3, reference numeral 303a denotes a power supply chamber, which is formed integrally with the electrolytic deposition tank 303.

Example 3 In Example 3, a zinc oxide thin film was deposited using the deposition apparatus shown in FIG. In this embodiment, the width is 120 mm, the length is 100 m, and the thickness is 0.15 m.
2,000 mm of aluminum is deposited on a stainless steel (SUS430BA) by DC magnetron sputtering, and 1000 mm of zinc oxide is deposited thereon by DC magnetron sputtering.
Used as This is mounted on a delivery roller 101, and the substrate 110 is transported at a transport speed of 20 along the illustrated path.
The sheet is conveyed at 0 cm / min, and is taken up by the take-up roller 102.

The aqueous solution of electrolytic deposition used for depositing zinc oxide contains 70 g of zinc nitrate hexahydrate and 0.5 g of dextrin in 1 liter of water, and is heated to 90 ° C. in advance in a preliminary tank (not shown). And an electrolytic deposition tank 103 by a pump (not shown).
Circulated and supplied to

At this time, the temperature of the electrolytic deposition aqueous solution was 85 ° C.
And the pH is kept between 4.0 and 6.0.
This aqueous solution was agitated with air in order to minimize temperature unevenness and concentration unevenness.

As the counter electrode 111 of the anode, zinc whose surface was buffed was used, and as the cathode, a power supply roller whose surface was made of stainless steel was used as the conductive member 109a. Shower 1
From 09b, a valve (not shown) was adjusted and supplied so that the same aqueous solution as the electrolytic deposition aqueous solution was uniformly and slightly applied to the entire surface of the power supply roller.

At this time, current was supplied so that a current density of 5.0 mA / cm ² (0.5 A / dm ² ) was kept constant between the power supply roller and the counter electrode, and electrolytic deposition was performed. In this way, by supplying the aqueous solution slightly to the surface of the power supply roller serving as the cathode, the electrical contact between the power supply roller and the conductive substrate became sufficient, and no voltage drop was observed during electrolytic deposition. .

Further, pure water is flowed through a shower (not shown) from the showers 109c and d between the position where the power supply roller contacts the conductive substrate and the position where the conductive substrate reaches the zinc oxide deposition bath 103c. Is supplied while being adjusted so that the surface of the conductive substrate does not dry.

Thereafter, the shower washing tank 104 and the water washing tank 1
After washing with water in order at 05, water is drained by an air knife 106, dried by a drying heater 107, and
2. The substrate is wound around the winding roller 102 as a substrate on which the zinc oxide transparent conductive layer 203 is formed.

Thus, the metal layer 2 is formed on the support 201.
02 and a transparent conductive layer 203 of zinc oxide were used as a substrate, and a semiconductor layer 204 having a triple structure was formed by a roll-compatible CVD apparatus.

That is, first, the substrate on which the metal layer 202 and the transparent conductive layer 203 are formed on the support 201 is heated to 340 ° C. using a mixed gas of silane, phosphine, and hydrogen, and 400 W of RF power is applied. An n-type semiconductor layer was formed.

Next, using a mixed gas of silane, germane and hydrogen, the substrate temperature was set to 450 ° C. and microwave power was applied to form an i-type semiconductor layer.

Further, at a substrate temperature of 250 ° C., a p-type semiconductor layer was formed from a mixed gas of boron trifluoride, silane and hydrogen to form a bottom nip layer.

Subsequently, the mixture ratio of silane and germane in the i-type semiconductor layer was increased, and the middle ni
A p-layer was formed, and an i-type semiconductor layer was further deposited from silane and hydrogen in the same procedure to form a top nip layer.

Thereafter, ITO was deposited as a transparent electrode layer 205 by a roll-compatible sputtering apparatus. Then, the current collecting electrode layer 206 was formed using a silver paste.

The photovoltaic device thus obtained was measured for short-circuit current density and conversion efficiency using a solar simulator (AM 1.5, 100 mW / cm ² , surface temperature 25 ° C.). As a result, 23 to 25 mA / cm ^{2 was obtained.} 9.5 to 10.
A photovoltaic element having excellent characteristics of 5% was obtained over the entire surface of the long conductive substrate in the longitudinal and width directions.

Comparative Example 1 Showers 109c and 109d
A zinc oxide thin film was deposited in the same manner as in Example 3 except that the supply of the aqueous solution from the substrate to the substrate surface was stopped.

When the substrate surface was observed after depositing the zinc oxide thin film, white spot-like patterns were observed in some places. This is because the high-temperature aqueous solution of 85 ° C was sprayed on the power supply roller, so that the aqueous solution dried on a part of the substrate surface and became uneven,
This is probably because a white spot pattern was formed when the zinc oxide thin film was formed thereon.

A photovoltaic device was fabricated by forming a semiconductor layer and the like on the zinc oxide thin film thus obtained in the same manner as in Example 3, and the characteristics were evaluated. Shunted, and the characteristics could not be measured.

[0098]

As described above, according to the present invention,
An oxide thin film such as a zinc oxide thin film can be continuously formed on a long conductive substrate by electrolytic deposition from an aqueous solution. At that time, the electrical contact between the conductive member and the back surface of the base is ensured, so that the voltage does not drop,
An oxide thin film can be deposited uniformly and stably over the entire length and width directions of the conductive substrate.

Further, by supplying water to both surfaces of the base between the position where the conductive member contacts the base and the position where the base is immersed in the aqueous solution, it is particularly possible to use a long conductive material for a long time at a high temperature. When forming a zinc oxide thin film on a substrate,
An oxide thin film can be deposited on the surface of the conductive substrate without generating unevenness or abnormal growth.

Furthermore, by introducing this oxide thin film forming technique as a transparent conductive layer into the process of manufacturing a photovoltaic element, characteristics such as an increase in short-circuit current density and conversion efficiency can be improved. In addition, material costs and running costs are about 100 times lower than those of the sputtering method and the vapor deposition method.
Since it is extremely advantageous, one in one, it can contribute to the full-fledged spread of photovoltaic power generation.

[Brief description of the drawings]

FIG. 1 is a schematic view schematically showing an example of a zinc oxide thin film deposition apparatus according to the present invention.

FIG. 2 is a schematic diagram schematically showing a cross-sectional structure of a photovoltaic device of the present invention.

FIG. 3 is a schematic view schematically showing another example of a zinc oxide thin film deposition apparatus according to the present invention.

[Explanation of symbols]

 Reference Signs List 101 delivery roller 102 take-up roller 103 electrolytic deposition tank 103a power supply chamber 103b overflow chamber 103c zinc oxide deposition bath 104 shower cleaning tank 105 water cleaning tank 106 air knife 107 drying heater 108 meandering correction roller 109a conductive member 109b, 109c, 109d shower Reference Signs List 110 conductive substrate 111 counter electrode 112 DC power supply 201 support 202 metal layer 203 transparent conductive layer 204 semiconductor layer 205 transparent electrode layer 206 current collecting electrode layer 301 delivery roller 302 winding roller 303 electrolytic deposition tank 303a power supply chamber 303b overflow chamber 303c Zinc oxide deposition bath 304 Shower washing tank 305 Water washing tank 306 Air knife 307 Drying heater 308 Meandering correction roller 309a Conductive member 309b shower 310 conductive substrate 311 counter electrode 312 DC power supply

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI // H01L 21/288 H01L 21/288 E

Claims (36)

[Claims] 1. An electrolytic deposition tank for forming an oxide thin film on a substrate by supplying a current to a conductive substrate and an electrode in an aqueous solution. A liquid supply means for supplying water or an aqueous solution to the cell. 2. The electrolytic deposition tank according to claim 1, wherein the aqueous solution supplied from the liquid supply means contains at least nitrate ions. 3. The electrolytic deposition tank according to claim 1, wherein the conductive member is formed as a power supply roller. 4. A water supply means for supplying water to both surfaces of the substrate between a position where the conductive member contacts the substrate and a position where the substrate is immersed in the aqueous solution. 3. The electrolytic deposition tank according to any one of 3. 5. The electrolytic deposition tank according to claim 4, wherein the conductive substrate is a conductive substrate having a zinc oxide thin film deposited on a deposition surface thereof in advance. 6. The electrolytic deposition tank according to claim 1, wherein the conductive substrate is a long substrate. 7. The electro-analysis according to claim 1, further comprising a roll-to-roll apparatus for depositing a film while moving a long substrate spanned between rolls. Departure tank. 8. An electrolytic deposition tank for forming an oxide thin film on a substrate by energizing a conductive substrate and an electrode in an aqueous solution, a washing means for washing the substrate passing therethrough, An apparatus for depositing an oxide thin film, comprising: a drying means for forcibly drying a substrate; a conductive member for supplying power by contacting the back surface of the substrate; and a liquid supply means for supplying water or an aqueous solution to the surface. An apparatus for depositing an oxide thin film. 9. The oxide thin film deposition apparatus according to claim 8, wherein the aqueous solution supplied from the liquid supply means contains at least nitrate ions. 10. The apparatus for depositing an oxide thin film according to claim 8, wherein the conductive member is formed as a power supply roller. 11. A water supply means for supplying water to both surfaces of the substrate between a position where the conductive member contacts the substrate and a position where the substrate is immersed in the aqueous solution. An apparatus for depositing an oxide thin film according to any one of claims 10 to 13. 12. The oxide thin film deposition apparatus according to claim 11, wherein the conductive substrate is a conductive substrate having a zinc oxide thin film deposited on a deposition surface thereof in advance. 13. The oxide thin film deposition apparatus according to claim 8, wherein the conductive substrate is a long substrate. 14. The oxide according to claim 8, wherein the oxide is provided in a roll-to-roll apparatus for depositing a film while moving a long substrate stretched between rolls. Thin film deposition equipment. 15. At least a nitrate ion, a zinc ion,
And an electrically conductive substrate immersed in an aqueous solution containing a carbohydrate and an electrode immersed in the solution, whereby an oxide thin film is formed on the substrate by applying an electric current. A method of depositing an oxide thin film, comprising supplying electricity while supplying water or an aqueous solution to the surface of a conductive member that supplies power by contacting the back surface of a substrate. 16. The method according to claim 15, wherein the aqueous solution supplied to the conductive member contains at least nitrate ions. 17. The method for depositing an oxide thin film according to claim 15, wherein a power supply roller is used as the conductive member. 18. The oxidation according to claim 15, wherein water is supplied to both surfaces of the base between a position where the conductive member contacts the base and a position where the base is immersed in the aqueous solution. Method of depositing a thin film 19. The method for depositing an oxide thin film according to claim 18, wherein a conductive substrate on which a zinc oxide thin film is deposited in advance is used as the conductive substrate. 20. The method for depositing an oxide thin film according to claim 15, wherein a long substrate is used as the conductive substrate. 21. The deposition of an oxide thin film according to claim 15, wherein the deposition is performed by a roll-to-roll method in which the film is deposited while moving a long substrate stretched between rolls. Method. 22. A photovoltaic device comprising an oxide thin film formed by the deposition method according to claim 15 as a transparent conductive layer. 23. at least nitrate ion, zinc ion,
A step of forming an oxide thin film on the substrate by applying a current between the conductive substrate immersed in an aqueous solution containing carbohydrate and an electrode immersed in the solution, and forming a semiconductor layer And forming a thin oxide film by supplying water or an aqueous solution to the surface of the conductive member to which power is supplied by contacting the back surface of the substrate. A method for manufacturing a photovoltaic element. 24. The method according to claim 23, wherein the aqueous solution supplied to the conductive member contains at least nitrate ions. 25. The method according to claim 23, wherein a power supply roller is used as the conductive member. 26. The light according to claim 23, wherein water is supplied to both sides of the substrate between a position where the conductive member contacts the substrate and a position where the substrate is immersed in the aqueous solution. A method for manufacturing an electromotive element. 27. The method for manufacturing a photovoltaic device according to claim 26, wherein a conductive substrate on which a zinc oxide thin film is previously deposited is used as the conductive substrate. 28. The method according to claim 23, wherein a long substrate is used as the conductive substrate. 29. The photovoltaic device according to claim 23, wherein the photovoltaic element is formed by a roll-to-roll method in which a film is deposited while moving a long substrate stretched between rolls. Production method. 30. at least nitrate ion, zinc ion,
And a conductive element immersed in an aqueous solution containing a carbohydrate, and a current flowing between the electrode immersed in the solution to form an oxide thin film on the substrate. A method for manufacturing a semiconductor element substrate, comprising supplying electricity while supplying water or an aqueous solution to the surface of a conductive member that supplies power by contacting the back surface of a base. 31. The method according to claim 30, wherein the aqueous solution supplied to the conductive member contains at least nitrate ions. 32. The method according to claim 30, wherein a power supply roller is used as the conductive member. 33. The semiconductor according to claim 30, wherein water is supplied to both surfaces of the base between a position where the conductive member contacts the base and a position where the base is immersed in the aqueous solution. A method for manufacturing an element substrate. 34. The method for manufacturing a semiconductor element substrate according to claim 33, wherein a conductive substrate having a zinc oxide thin film previously deposited on its deposition surface is adopted as the conductive substrate. 35. The method of manufacturing a semiconductor element substrate according to claim 30, wherein a long substrate is used as the conductive substrate. 36. The method of manufacturing a semiconductor element substrate according to claim 30, wherein the method is performed by a roll-to-roll method of depositing a film while moving a long substrate stretched between rolls. Method.