JP3423607B2 - Electrodeposition equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrodeposition apparatus for forming an oxide film on a substrate by an electrodeposition method (electrolytic plating method and electrolytic deposition method), and particularly to zinc oxide uniformly on a long substrate. The present invention relates to an electrodeposition apparatus for forming a film.

[0002]

2. Description of the Related Art In recent years, attention has been paid to a technique for producing an oxide on a substrate by utilizing an electrochemical reaction of an aqueous solution instead of a vacuum process in manufacturing a photovoltaic element. For example, Japanese Patent Application Laid-Open No. 09-092861 proposes an invention relating to "a method for manufacturing a photovoltaic element", which is a method of forming an oxide such as zinc oxide on a long substrate by an electrodeposition method, and A device is disclosed.

FIG. 2 is a schematic view showing an example of an apparatus for producing an oxide by the electrodeposition method based on the publication, and is a simplified one having a function of only producing a zinc oxide film by the electrodeposition method. Is.

In FIG. 2, reference numeral 2001 denotes a long substrate such as a stainless steel strip rolled in a roll shape, which is called a hoop material, a roll substrate or a web. Long board 2
001 is a cylindrical substrate wound in a coil on a bobbin and conveyed to this apparatus.

In this apparatus, a coil-shaped long substrate 2001 is used.
Is disposed on the substrate feeding roller 2002, and the interleaving paper wound to protect the surface thereof is unwound by the interleaving paper winding roller 2003, while the unwound substrate is conveyed to the substrate winding roller 2062 and wound. .

That is, the substrate 2001 first enters the electrodeposition tank 2009 through the tension detecting roller 2005 and the power feeding roller 2006 in the transport path. Electrodeposition tank 20
In the inside of 09, the substrate 2001 has the support roller 201.
3, 2014, and an oxide film is formed by the electrodeposition method.

Next, the substrate 20 that has passed through the electrodeposition tank 2009
01 is introduced into the washing tank 2030 and washed with water. Positioning inside the washing tank 2030 is performed by the support roller 20.
31, 2066. The substrate 2001 that has passed through the water washing tank 2030 is introduced into the warm air drying oven 2051 and dried.

The substrate 200 that has passed through the warm air drying oven 2051
1, the lateral deviation is corrected by the meandering correction roller 2059 through the support roller 2057, and new interleaf paper fed from the interleaf paper feed roller 2060 is rolled in to protect the film formation surface, and the substrate winding roller 2062
It is rolled up and is transported to the next process if necessary.

The tension detecting roller 2005 is provided on the substrate 200.
The dynamic winding tension of No. 1 is detected, the feedback is applied to a braking means such as a powder clutch (not shown) linked to the shaft of the substrate feeding roller 2002, and the tension is kept constant. Thereby, the transport path of the substrate 2001 is designed to have a predetermined value between the support rollers.

In particular, in this apparatus, since the roller does not touch the film-forming surface, when the tension is weak, the substrate 2001 is detached from the supporting roller, and the substrate is removed at the entrance / exit of the electrodeposition tank 2009 or the washing tank 2030. Problems such as 2001 hanging down and rubbing the film forming surface to cause scratches occur.

The device structure in which the film-forming surface does not touch has an advantage that the film-forming surface is not damaged or soiled, and in particular, micron-sized irregularities are formed on a thin film such as a reflective film of a solar cell. Preferred for applications that must be formed.

The feeding roller 2006 is for applying a potential on the cathode side to the long substrate, is installed as close to the electrodeposition bath as possible, and is connected to the negative side of the power source 2008.

The electrodeposition bath 2009 holds the electrodeposition bath 2016, determines the path of the substrate 2001, and installs the anode electrode 2017 on the path of the substrate 2001.
A positive electrode potential is applied to the power source 017 from the power source 2008 via the power feeding bar 2015. This allows the substrate 20 to be placed in the electrodeposition bath.
The electrochemical electrolytic deposition process in which 01 is negative and the anode electrode 2017 is positive proceeds.

When the electrodeposition bath 2016 is kept at a high temperature,
Since the amount of water vapor is considerably increased, the steam exhaust duct 2
Let water vapor escape from 010, 2011 and 2012.

In order to stir the electrodeposition bath 2016,
Air is introduced from the stirring air introduction pipe 2019, and air is bubbled from the air blowing pipe 2018 inside the electric tank 2009.

In order to replenish the high temperature bath liquid to the electrodeposition tank 2009, an electrodeposition circulation tank 2025 is provided in which the heater 20 is provided.
24 is installed to heat the bath, and the bath liquid is supplied from the bath circulation pump 2023 to the electrodeposition tank through the electrodeposition bath liquid supply pipe 2020. The bath liquid overflowing from the electrodeposition tank 2009 or the bath liquid to be partially positively returned is returned to the electrodeposition circulation tank 2025 via a return path (not shown) and heated again.

When the discharge amount of the pump is constant, the valve supply amount from the electrodeposition circulation tank 2025 to the electrodeposition tank 2009 can be controlled by the valve 2021 and the valve 2022. That is, when increasing the supply amount, the valve 2021
Is opened more and the valve 2022 is closed more, and when the supply amount is reduced, the reverse operation is performed. The water level held in the electrodeposition bath 2016 is adjusted by adjusting the supply amount and the return amount (not shown).

The electrodeposition circulation tank 2025 includes a circulation pump 20.
A filter circulation system composed of 27 and a filter is provided, and is configured to remove particles in the electrodeposition circulation tank 2025. Electrodeposition circulation tank 2025 and electrodeposition tank 2009
In the case where the supply and return of the bath liquid between and are sufficiently large, a sufficient particle removing effect can be obtained by thus installing the filter only in the electrodeposition circulation tank 2025.

In this apparatus, a vapor discharge duct 2026 is also installed in the electrodeposition circulation tank 2025, and has a structure for discharging steam. In addition, since the heater 2024 is installed in the electrodeposition circulation tank 2025 as a heating source, steam is remarkably generated, and it is not preferable that the generated steam is inadvertently released or condensed. The case is extremely effective.

The electro-folding preliminary tank 2029 is installed in order to prevent the treatment apparatus from being damaged by flowing the heated bath liquid into the existing waste liquid system at once. This is for holding and holding the electrodeposition tank 2009 empty to improve work efficiency.

Substrate 200 after electrodeposition in the electrodeposition tank 2009
Next, No. 1 enters the washing tank 2030 and is washed with water. In the washing tank 2009, the substrate 2001 is the support roller 203.
1 and the support roller 2066, and passes through the first water washing tank 2032, the second water washing tank 2033, and the third water washing tank 2034 in order.

Washing circulation tanks 2047 to 2049, respectively
And water circulation pumps 2044 to 2046, and two valves, that is, a valve 2038 and a valve 2041, or a valve 2039 and a valve 2042, or a valve 2.
040 and the valve 2043 determine the amount of water supplied to the washing tank 2009, and the supply pipe 2035 or the supply pipe 203.
6, or the washing tank 2032 through the supply pipe 2037
Wash water is supplied into 2034.

The control method of the supply amount by the two valves is the same as the control in the electrodeposition tank 2009. In addition, the electrodeposition tank 200
As in the case of 9, the return water (not shown) that collects the overflow and positively returns a part of
It is also possible to return to ~ 2049.

Generally, in the three-stage washing system as shown in FIG. 2, the washing tank on the upstream side to the washing tank on the downstream side in the substrate carrying direction, that is, the first washing tank 2032 to the third washing tank 20.
Toward 34, the purity of the wash water is increasing. This means that the cleanliness of the substrate 2001 increases as the substrate 2001 is transported and the process is near the end.

This means that the washing water is supplied to the third washing circulation tank 20.
49 is first replenished, then the second washing circulation tank 2049 is replenished with the washing water overflowing from the third washing circulation tank 2049, and the first washing circulation tank 2047 is replenished with the washing water overflowing from the second line-of-sight circulation tank 2048. By replenishing the water, it can be achieved by significantly saving the amount of water used.

The substrate 2001 which has been washed with water is washed with the washing tank 2
It is drained by an air knife 2065 provided in a part of 030, and then conveyed to a warm air drying furnace 2051.
Here, the drying is performed with convection air having a temperature sufficient to dry the water. The convective air supplies hot air generated in the hot air generating furnace 2055 by removing dust from the hot air blowing pipe 2052 through a filter 2054.

The overflowing air is again collected from the warm air collecting pipe 2053, mixed with the outside air from the outside air introducing pipe 2056, and sent to the hot air generating furnace.

The conveyance path of the substrate 2001 in the warm air drying furnace is positioned by the support roller 2066 and the support roller 2057.

The meandering correction roller 2059 is provided on the substrate 200.
Substrate winding roller 20 by correcting the deviation of 1 in the width direction
A sensor (not shown) detects a deviation amount and controls the meandering correction roller 2059 by rotating the meandering correction roller 2059 with an arm (not shown) as a fulcrum. Normally, the amount of deviation detected by the sensor also determines the meandering correction roller 2
The operation amount of 059 is also extremely small and does not exceed 1 mm.

When the substrate 2001 is wound up, new interleaving paper is supplied from the interleaving paper feeding roller 2060 in order to protect the surface film.

Stopper 2007 and stopper 2058
Simultaneously works to make the substrate 2001 stand still with the transport tension applied. This improves workability when the substrate 2001 is replaced or when the apparatus is maintained.

The use of the electrodeposition apparatus as shown in FIG. 2 has the following advantages.

First, unlike a vacuum device such as a sputtering device, film formation is extremely simple. There is no need for an expensive vacuum pump, and there is no need to worry about the power supply for using plasma or the design around the electrodes.

Next, in most cases, the running cost is low. This is because the sputtering equipment requires manpower and equipment to manufacture the target, and is expensive.
This is because the utilization efficiency of the target is about 20% or less. Therefore, when the throughput of the apparatus is increased or the film thickness is large, the target replacement work occupies a considerable weight.

Other than sputtering, it is also superior in terms of equipment and running cost to CVD and vacuum deposition methods.

In many cases, the film is made of polycrystal fine particles, and exhibits conductive and optical characteristics comparable to those produced by the vacuum method, and a sol-gel method, a coating method using an organic substance, and a spray pyrolysis method. It has an advantage over the law.

Further, even when the oxide is formed, the above is established, the waste liquid can be easily treated, the influence on the environment is small, and the cost for preventing environmental pollution is low.

[0038]

However, the following inconveniences were found when the film was formed by the above electrodeposition apparatus.

That is, there was a phenomenon in which the film thickness unevenness in the width direction of the long substrate 2001 was large, and almost no film was formed at both end portions as compared with the central portion in the width direction. This film thickness unevenness is not mentioned in the above-mentioned publication, but the present inventors have found that the structure of the anode electrode affects the film thickness unevenness in the width direction of the substrate.

The present invention can uniformly deposit a uniform oxide film on a long substrate without causing film thickness unevenness, and can form an oxide film suitable for a reflective layer of a solar cell. It is an object of the present invention to provide an electrodeposition apparatus that can be used.

[0041]

In order to achieve the above object, the present invention comprises an electrodeposition tank for forming an oxide film on a substrate by energizing a substrate and an anode electrode in an electrodeposition bath. In the electrodeposition apparatus described above, the width of the anode electrode is set to be equal to or larger than the width of the opposing substrate.

This anode electrode preferably has a mesh structure.

The anode electrode is preferably made of zinc or a non-reactive metal.

Further, the anode electrode is preferably covered with a dielectric enclosure.

The enclosure of the dielectric is preferably set such that the enclosure width along the substrate width direction is equal to or larger than the width of the opposing substrate.

Fluororesin is preferably used as the dielectric.

Furthermore, it is preferable that the substrate is a long substrate, and more preferably, it is provided in a roll-to-roll device that carries the long substrate between the rolls and conveys it.

As described above, the present invention relates to a novel electrodeposition apparatus, and the constitution and operation of the present invention will be further described below.

In an electrodeposition apparatus equipped with an electrodeposition tank for forming an oxide film on a substrate by energizing the anode substrate and the electrode in the electrodeposition bath, the width of the anode electrode is the width of the opposing substrate. Is set equal to or greater than.

This is because if the width of the anode electrode is smaller than the width of the substrate, the film thickness unevenness of the oxide film in the substrate width direction will be remarkably large.

Since the anode electrode is formed in the mesh structure, the stirring of the bath between the anode electrode and the substrate is effectively promoted, and the retention of bubbles is effectively removed.
The fatigued bath never stays on the substrate surface.

By forming the anode electrode from zinc, it is possible to form a zinc oxide film which is uniform and suitable for the reflective layer. By forming it from a non-reactive metal, the anode electrode is reduced. Is not required to be considered so that it is advantageous for long-time film formation.

Further, by covering the anode electrode with an enclosure of a dielectric material, stray current other than the current flowing from the anode electrode to the substrate is effectively reduced and the controllability of film formation is improved.

Further, the enclosure of the dielectric is set such that the enclosure width along the substrate width direction is equal to or larger than the width of the opposing substrate.

This is because when the electric conductivity of the electrolysis bath used is high, the enclosure width of the dielectric enclosure effectively acts as the width of the anode electrode instead of the width of the anode electrode. The degree of freedom in design can be increased with respect to the mechanical accuracy of the electrode and the reduction of the anode electrode after long-term use.

It is preferable to use a fluororesin as the dielectric because it has corrosion resistance to the electrodeposition bath.

Since the above-mentioned substrate is a long substrate and is provided in a roll-to-roll device that carries the long substrate between rolls and conveys it, uneven film thickness does not occur on the long substrate. It is possible to form a uniform oxide film uniformly and continuously.

[0058]

BEST MODE FOR CARRYING OUT THE INVENTION A preferred embodiment of the electrodeposition apparatus of the present invention will be described below, but the present invention is not limited to this embodiment.

The main constituent elements of the electrodeposition apparatus of this embodiment basically have the same structure as the electrodeposition apparatus shown in FIG. 2, but in order to solve the problems in the apparatus, Various improvements have been added. Therefore, for convenience, FIG.
The description will be given with the same reference numerals.

That is, the electrodeposition apparatus of this embodiment is an apparatus for continuously forming a uniform oxide film on the long substrate 2001, and the long substrate 2001 and the anode electrode 2017 in the electrodeposition bath 2016. Energizing the substrate 2001 to form an oxide film on the substrate 2001, a washing means such as a washing tank 2030 for washing the substrate 2001 passing through the electrodeposition tank 2009, and a substrate 2001 passing through the washing means 2030. And a drying means such as a warm air drying oven 2051 for forcibly drying the anode electrode 2017. In particular, the configuration of the anode electrode 2017 is improved.
Hereinafter, each component will be described in detail.

[Substrate] The substrate 2001 used in the present invention
The material of No. 2 has electrical continuity on the film forming surface, and the electrodeposition bath 20
It can be used as long as it is not corroded by 16, stainless steel (SUS), Al, Cu, Fe, C
Metals such as r and alloys thereof are used. Further, a PET film having a metal coating can be used.

Among these, stainless steel is suitable as a long substrate in that it is relatively inexpensive and has excellent corrosion resistance for performing an element formation process in a later step.

The substrate surface may be a polished mirror surface, a smooth surface such as BA, or a rough surface represented by 2D. In the case of a rough surface of 1 μm or more, even if a film having good wettability is formed, the electrodeposition tank 2009 and the water washing tank 203
When it is 0, uneven drying is likely to occur.

Further, another conductive material may be formed on the substrate 2001, and it is selected according to the purpose of electric folding.

In the case of a long substrate of stainless steel or Cr,
Since the electrical resistance is higher than that of other metals, particularly when the thickness of the substrate is about 0.1 mm or less, the electrodeposition bath 2016 described later is used.
It is often higher than the electrical resistance between the anode electrode 2017 and the substrate 2001 via the electrode.

In such a case, it is difficult to control the anode potential with respect to the substrate 2001, or the current that should flow between the substrate 2001 and the anode electrode 2017 escapes from other members such as the electrodeposition tank itself or the piping. It will be difficult to control. The difficulty of controlling the anode potential often results in the problem of unevenness as described above, and the present invention is particularly effective in such a case.

[Electrodeposition Tank] Examples of the electrodeposition tank used in the present invention include metals such as stainless steel (SUS) and F.
Since e, Al, Cu, Cr, brass, etc. are excellent in heat resistance and workability, they can be used, and stainless steel is preferable in consideration of corrosion resistance. As the stainless steel, any of ferrite type, martensite type and austenite type is applicable.

When heat retention is required, a double structure can be used and the space between the tank walls can be supplemented with a heat insulating material. Examples of the heat insulating material include air, oil and fat, glass wool, urethane resin, etc. in consideration of temperature and simplicity.

[Electrodeposition Bath] As the electrodeposition bath 2016 contained in the electrodeposition tank 2009, a well-known metal plating bath and a zinc nitrate film-forming zinc nitrate-based bath are mainly applied. It is possible. Sugars such as sucrose and dextrin can be added to increase the uniformity of the film.

When indium oxide is deposited, it is preferable that the indium nitrate content is 0.0001 M / l or more and the saccharides are contained in the same amount. However, the bath temperature is preferably lower than 60 ° C.

[Oxide Film] Examples of the oxide film according to the present invention include a zinc oxide polycrystalline film oriented to the c-axis and a zinc oxide polycrystalline film having the c-axis tilted. Other oxide films include indium oxide deposited from indium nitrate.

In particular, in order to form a zinc oxide film having irregularities of about the wavelength of light effective as a light confining reflection layer of a solar cell, it is preferable that the concentration of zinc nitrate is 0.1 M / l or more. In order to obtain a zinc oxide film oriented along the c-axis, it is generally preferably 0.05 M / l or less, though it depends on the substrate.

In any case, it is preferable that the sugars to be added be 3 g / l or more for sucrose and 0.01 g / l or more for dextrin. In these cases, the temperature of the bath is preferably 60 ° C. or higher because there is no metal precipitation. Especially when it is 80 ° C or higher,
It is preferable because the uniformity of the film is improved. Therefore, at these temperatures, the effect of the present invention becomes more remarkable.

[Anode Electrode] The anode electrode 2017 used in the present invention refers to an electrode having a positive potential with respect to the substrate 2001 and allowing an electrodeposition current to flow toward the substrate 2001. Usually, as shown in FIG. 2, it is arranged so as to face and be close to the substrate 2001.

The electric power applied to the anode electrode is preferably controlled by current rather than voltage in order to facilitate the control of film formation, and side reactions are suppressed to form a film having a desired morphology. It is preferable that the voltage is controlled.

In the application as a solar cell, since the film thickness is often important, current control is often used. In the case of current control, the voltage drop at the electrical connection from the power supply to the anode electrode can be ignored to some extent, which is preferable. In particular, when the electric conductivity of the electrodeposition bath is high, it is easier to control the current.

The size of the anode electrode according to the present invention in the width direction of the long substrate (hereinafter, simply referred to as "anode electrode width").
In some cases. ) Is set equal to or larger than the width of the long substrate. This is extremely important according to experiments conducted by the inventors of the present invention. When the width of the anode electrode is smaller than the width of the long substrate, the unevenness of the oxide film in the substrate width direction is significantly increased. Therefore, the width of the anode electrode must be equal to or larger than the width of the long substrate.

In particular, in the present invention, in order to form an oxide film, not only the metal ions must be carried by the electric field but also the oxidation reaction must proceed in the immediate vicinity of the substrate. Therefore, the potential for maintaining the oxidation reaction must be maintained. (Potential between the bath solution and the substrate) must be secured, and we believe that an approach different from metal plating is necessary. That is, it should be clarified by experimental examination.

In fact, in metal plating, the edge of the substrate on which the electric field is concentrated is the most advanced portion of film formation,
The oxide film formation of the present invention may exhibit opposite characteristics. Further, in the experiment in the beaker, sufficient film formation was observed on the surface of the substrate opposite to the counter electrode, so it should be considered that a mechanism other than the electric field is working.

The mechanical precision of the distance between the anode electrode and the substrate is the most important factor, but it is 1 mm or more and several tens of cm.
The following is preferable, and more preferably 10 mm
It is preferable to dispose them at a distance of about 50 mm because the effect can be maximized. Also, anode electrodes that have the same potential are placed at the same distance (that is,
It is preferable to arrange them in parallel to the substrate).

The size of the anode electrode in the substrate carrying direction is
It can be freely set from about 0.1 mm to 1 m or more. This is because the averaging progresses efficiently by the transportation. Therefore, the shape of the anode electrode can be a plate shape, a linear shape, a rod shape, a mesh shape as described later, or a lattice shape. Both are determined by the ease of mechanical assembly and the ease of holding the electric potential.

Usually, a plurality of anode electrodes are arranged in the electrodeposition bath because they are arranged at a distance to the carrier substrate that draws a catenary line, and the potential and shape at this time are the same for each anode electrode. No need.

For example, a film having a large film-forming rate but not having a large unevenness on the side closer to the substrate and on the side farther from the substrate (ie, when the solar cell active layer is formed on the oxide film,
In the case of a film with large irregularities on the side close to the active layer) and a low deposition rate, the anode electrode in the first half of the process is brought closer to maintain a high potential to increase the electrodeposition current, and the anode electrode in the latter half of the process is increased. Is further separated to keep the electric potential low to reduce the electric breakdown current. In this case, the shape can be selected such that the plate-shaped anode electrode is arranged in the first half of the process and the rod-shaped anode electrode is arranged in the latter half of the process.

<Zinc> As the zinc applicable to the anode electrode of the present invention, not only pure zinc having a purity of 4N but also 2N and 3N zinc can be used. Impurity elements mixed in during refining do not pose a problem.

As the reaction progresses, zinc oxide powder is collected on the surface of the zinc anode electrode, which can be removed by washing with dilute nitric acid. Moreover, even if the zinc oxide powder is put together, the powder itself does not adversely affect the reaction, and if the powder removal system by the filter 2054 as shown in FIG. Since it can be removed, the actual harm is small.

<Non-Reactive Metal> The non-reactive metal applicable as the anode electrode of the present invention includes stainless steel (SUS) and Ti which passivate by forming an oxide film on the surface in a bath.
Can be used. Ti can also be sprayed and used on the surface of stainless steel. Further, in the case of a current in which no gas generation is seen, noble metal such as Pt can be used. However, in order to reduce the cost, it is preferable to use stainless steel.

While stainless steel may release the metal atoms contained in it into the metal ions of the electrodeposition bath, Ti is excellent because it forms an effective passivation. Further, although metals such as Pt are expensive, they are preferable in the sense that they do not adversely affect the reaction even if they dissolve in the bath.

When a non-reactive metal is used as the anode electrode, the concentration of Zn ions gradually decreases as it is. Therefore, a bath solution having a high zinc concentration may be prepared and added, or a lump of zinc may be added. It is also possible to immerse the zinc into the electrodeposition bath, and in the latter case, zinc ions lost in the bath will be automatically replenished from the zinc lump.

<Mesh Structure> The mesh structure applicable as the anode electrode of the present invention includes a plate having a round opening, a plate having a square opening, a grid composed of rods, a net woven by a wire rod, and the like. The feature of the mesh structure is that the potential is kept almost the same over the entire surface of the mesh, and the bath liquid can freely flow in and out through the gap.

As a result, a new reaction agent can always be present between the anode electrode and the substrate, and the effect of suppressing unevenness in film thickness is further improved. In order to improve the inflow and outflow of the bath liquid, the convection of the bath may be positively caused in the gap of the mesh, or the stirring air may be passed.

[Dielectric Enclosure] The dielectric enclosure used in the present invention effectively reduces stray current other than the current flowing from the anode electrode to the substrate to improve the controllability of film formation. The stray current is generated by the escape of the electric current through the bath liquid having an extremely high electric conductivity when an electric connection path exists between the substrate and the metal electrodeposition tank or the pipe.

Therefore, in the case of the electrodeposition bath having a high electric conductivity as used in the present invention, it is effective to cover the anode electrode with the dielectric enclosure in order to suppress the stray current.
However, like the width of the anode electrode, this also involves the reaction mechanism of electrodeposition, so it cannot be determined by analogy from the plating process, and should be clarified by experimental examination.

As the material of the dielectric material forming the enclosure, glass, ceramics, and resins generally showing corrosion resistance to the bath liquid are used. Especially considering heat resistance and workability, PFA
Fluorine resins such as (tetrafluoroethylene / perfluoroalkyl vinyl ether), ETFE (tetrafluoroethylene / ethylene), and Teflon are preferably used. When the temperature of the electrodeposition bath is low, PP (polypropylene) or heat-resistant vinyl chloride is also possible.

The direction covered with the dielectric enclosure used in the present invention is particularly effective in the width direction of the substrate. The enclosure of the dielectric does not necessarily have to be a box-shaped enclosure, and it is possible to dispose the dielectric enclosure so as to cover a specific direction with a single plate, for example. Further, when the stray current on the side opposite to the substrate, that is, on the bottom side of the electrodeposition tank 2009 shown in FIG. 2 is large, it is effective to cover that portion, and air bubbles of air stirring are discharged from the bottom. If it is necessary to reach the surface of the substrate by opening it, it may be opened.

In the case where the dielectric enclosure used in the present invention covers the width direction of the substrate, the distance between the enclosures should be at least equal to or larger than the width of the substrate to minimize unevenness in film thickness. It has been clarified by experiments by the present inventors that it is preferable to According to the experiment, in the area outside this enclosure, film formation was not suddenly performed.

[Washing Means] As the water washing means, a method of passing the substrate 2001 through the water stored in the water washing tank 2030 as shown in FIG. 2 and a shower for water washing can be used.

[Drying Means] In the drying means, after sufficiently removing the water-soluble solute, draining with an air knife as shown in FIG. 2 is extremely effective, and warm air is sufficient for the subsequent heating and drying. is there. When a vacuum device is used in the subsequent step, an infrared heater or the like can be used to remove adsorbed water.

[Conveying Means] In the substrate conveying means used in the present invention, in order to prevent vertical vibration of the substrate and unevenness in steps between the tanks, 0.5% per 1 cm width of the substrate.
It is preferable to apply a tension of not less than kg.

Although FIG. 2 shows the horizontal transfer of the substrate, diagonal transfer of the substrate using a folding roller between the tanks can also be applied.

[0100]

Embodiments of the present invention will be described below with reference to the accompanying drawings, but the present invention is not limited to these embodiments.

Example 1 (Zn Flat Plate) The anode electrode shown in FIG. 1 was incorporated in the electrodeposition apparatus shown in FIG. In FIG. 1, the anode electrode 1001 is a plate made of zinc having a purity of 4N, and the long substrate 1
It is arranged in parallel with 002. An anode width 1005 and an anode length 1006 are defined with respect to a substrate transfer direction 1003 indicated by an arrow.

The substrate width 1007 of the long substrate 1002 is 12
In order to improve the reflection characteristics, the thickness is set to 0 mm and the Al and ZnO films are previously formed as the undercoat layer by sputtering to 200 mm.
A stack of 0Å was used.

The anode width 1005 is 140 mm, the anode length 1006 is 300 mm, and the anode facing surface 1004.
The distance between the substrate and the substrate 1002 was 20 mm. Nine such anode electrodes 1001 were used, were arranged at equal intervals in the electrodeposition tank of FIG. 2, and a current of 2 A was supplied from each of different power supplies.

As the electrodeposition bath 2016, one having a zinc nitrate concentration of 0.2 M / l and a dextrin concentration of 0.07 g / l at 85 ° C. was used. The substrate transfer speed is 800 mm / sec
And

When a zinc oxide film was formed in this manner, a zinc oxide film having a film thickness of 9000Å was formed with almost no unevenness in film thickness in the substrate width direction. About 2 mm at the end,
A sudden thinning of the film was seen, which was not a problem as it was constant over the length of the long substrate and could be trimmed and removed in a subsequent process.

When the surface image is observed by FESEM, c
It was confirmed to be a polycrystalline phase in which zinc oxide crystal grains inclined to the axis were gathered. In addition, no unevenness was visually observed over the entire film formation surface. Using the zinc oxide film thus obtained as a reflective layer, a-Si / a-SeGe / a-SiGe
The triple structure photovoltaic element was formed by a long substrate CVD apparatus. When the light collecting current of this photovoltaic element was evaluated, it was found to be 22 mA / cm ^2, and it was excellent as a reflective layer of the photovoltaic element.

Example 2 (Zn Rod) The anode electrode as shown in FIG. 3 was incorporated in the electrodeposition apparatus shown in FIG. In FIG. 3, an anode electrode 3001
Is formed of zinc having a purity of 4N in the shape of a round bar, and
It has an anode width 3005 of 50 mm. The anode electrode 3001 is arranged parallel to the film formation surface of the long substrate 3002 having a substrate width 3007 of 120 mm. The distance between the anode electrode 3001 and the substrate 3002 is 10 m
set to m.

Twelve such anode electrodes 3001 are used to make a set of three, and a current of 8 A is supplied from each of the four independent power supplies, and the substrate transfer speed is 500 mm / sec.
The substrate was transported in the substrate transport direction 3003 indicated by the arrow, and zinc oxide was deposited on the same substrate in the same electrodeposition bath as in Example 1. The film thickness of the zinc oxide film was 6000Å, and as in Example 1, no film thickness unevenness was observed.

Using the zinc oxide film thus obtained as a reflection layer, a-Si / a-SeGe / a-Si was obtained as in Example 1.
CVD of Ge triple structure photovoltaic element for long substrate
It was formed by the device. When the light collecting current of this photovoltaic element was evaluated, it was 21.8 mA / cm ² , which was excellent as a reflective layer of the photovoltaic element.

The advantage of using such a rod-shaped anode electrode 3001 is that there is a degree of freedom in setting the anode interval and the anode current, and the unevenness of the film can be controlled (for example, the film formation of 200 Å / sec like the main bath). The unevenness becomes slower at the speed), which is easy in the growth direction of the film.

[Example 3] (Zn mesh) The anode electrode as shown in Fig. 4 was incorporated in the electrodeposition apparatus shown in Fig. 2. In FIG. 4, an anode electrode 4001
Is a zinc plate made of mild zinc having a purity of 2N and provided with a mesh opening of 5φ, and has an anode width 4005 of 140 mm and an anode length 4006 of 300 mm. The anode electrode 4001 is arranged such that its anode facing surface 4004 is parallel to a long substrate 4002 having a substrate width 5007 of 120 mm.

Nine sheets of this anode electrode were used, and 2 A each was supplied from nine independent power sources for each anode electrode.
The current was applied. Substrate transfer speed is 500mm / sec
The substrate was transported in the substrate transport direction 4003 indicated by the arrow, and a zinc oxide film was formed on the same substrate in the same bath as in Example 1. The film thickness of the zinc oxide film was 5500Å, and as in Example 1, no film thickness unevenness was observed.

Using the zinc oxide film selected in this way as a reflection layer, a-Si / a-SeGe / a-S was obtained as in Example 1.
iGe triple structure photovoltaic device for long substrate CV
It was formed by a D device. When the light collection current of this photovoltaic element was evaluated, it was found to be 22.2 mA / cm ^2, and it was excellent as a reflective layer of the photovoltaic element.

Anode electrode 4 having such a mesh structure
The advantage of using 001 is that the bath between the anode electrode 4001 and the substrate 4002 is effectively stirred, bubbles are effectively retained, and the fatigued bath never stays on the substrate surface. And so on. This is particularly effective when the substrate is transported at a low speed and the substrate is subjected to a film forming process in the electrodeposition tank for a long time.

[Example 4] (SUS mesh) Instead of the zinc mesh anode electrode of Example 3, a mesh anode electrode made of stainless steel (SUS304) having the same size was used. The apparatus configuration and zinc oxide film forming conditions were the same as in Example 3. As a supply source of Zn ions, a 4N-purity zinc lump was placed on the bottom of the electrodeposition tank. The film thickness of the zinc oxide film was 5400Å, and similar to Example 3, no film thickness unevenness was observed.

Using the zinc oxide film thus obtained as a reflection layer, a-Si / a-SeGe / a-S was obtained in the same manner as in Example 3.
iGe triple structure photovoltaic device for long substrate CV
It was formed by a D device. When the light collecting current of this photovoltaic element was evaluated, it was 21.9 mA / cm ² , which was excellent as a reflective layer of the photovoltaic element.

In this embodiment, since the anode electrode made of stainless steel is used, changes in the anode electrode itself (for example,
It is advantageous for long-time film formation because it is not necessary to take into consideration the decrease of the anode electrode).

Example 5 (Enclosure) The anode electrode as shown in FIG. 5 was incorporated in the electrodeposition apparatus shown in FIG. In FIG. 5, the anode electrode 500
No. 1 is made of ZnO with a purity of 4N and has an anode width 5005 of 330 mm.

The anode electrode 5001 is arranged such that its anode facing surface 5004 is parallel to the film forming surface of the long substrate 5002. This long substrate 5002 has 35
It has a substrate width 5007 of 5 mm.

The anode electrode 5001 has a length of 370 m.
P with an encircling width of 500 m and an encircling length of 300 mm
Four sides are covered with a rectangular frame-shaped enclosure 5009 made of FA. No PFA enclosure is provided on the bottom surface of the anode electrode 5001 opposite to the anode facing surface 5004.

Using six such anode electrodes, a current of 5.5 A was applied to each anode electrode from six independent power supplies. Substrate transport speed 400mm
/ Sec, the zinc oxide film was formed in the same bath as in Example 1. The film thickness of the zinc oxide film was 11,000Å, and as in Example 1, no film thickness unevenness was observed.

Using the zinc oxide film thus obtained as a reflective layer, a-Si / a-SeGe / a- was prepared in the same manner as in Example 1.
A photovoltaic element with a triple structure of SiGe is used for long substrate C
It was formed by a VD device. When the light collecting current of this photovoltaic element was evaluated, it was 23.1 mA / cm ² , which was excellent as a reflective layer of the photovoltaic element.

In this embodiment, since the electric conductivity of the electrolysis bath is high, the enclosure width 5008 of the enclosure 5009 effectively acts as the width of the anode electrode instead of the anode width described in the first embodiment. Therefore, it is possible to increase the degree of design freedom with respect to the mechanical accuracy of the anode electrode and the reduction of the anode electrode after long-term use.

[Embodiment 6] (Combination of different currents,
(A part with a large current is enclosed.) An anode electrode as shown in FIG. 6 was incorporated in the electrofolding device shown in FIG. In FIG. 6, with respect to a long substrate 6002 having a substrate width of 355 mm, a rod-shaped anode electrode 601 similar to that in Example 2 was used in the electrolysis bath of the electrolysis bath 6011.
2, 6013, 6014, 6015 and the same anode electrodes 6016, 6017, 6018, 601 as in Example 5.
The substrate 6002 was conveyed so as to be opposed to the substrate 9. However,
Zinc having a purity of 3N was used for the rod-shaped anode electrode, and the anode width was 360 mm.

These anode electrodes 6012 to 6019
In groups of two, four independent current sources 6020, 6
021, 6022, and 6023. A current return path is secured from the power feeding roller 6010 that rotates in contact with the substrate 6002.

The current from the power source 6020 is 16 A, the power source 6
The current from 021 is 18 A, the current from the power source 6022 is 6 A, the current from the power source 6023 is 2 A, and the substrate is transported at a substrate transport speed of 400 mm / sec in the substrate transport direction 6003 indicated by the arrow in the same bath as in Example 1. Then, a film of zinc oxide was formed. The film thickness of the zinc oxide film was 7,000 Å, and as in Example 1, no film thickness unevenness was observed.

Using the zinc oxide film thus obtained as a reflective layer, a-Si / a-SeGe / a- was prepared in the same manner as in Example 1.
A photovoltaic element with a triple structure of SiGe is used for long substrate C
It was formed by a VD device. When the light collecting current of this photovoltaic element was evaluated, it was 22.5 mA / cm ² , which was excellent as a reflective layer of the photovoltaic element.

In the structure of this embodiment, the grain size of zinc oxide to be formed and the film forming rate can be changed in accordance with the film growth, whereby the unevenness optimized as the light confinement of the solar cell by the film thickness is obtained. Can be selected.

[0129]

As described above, according to the present invention,
A uniform oxide film without unevenness in film thickness can be uniformly electrodeposited on a long substrate, and an oxide film suitable for a reflective layer of a solar cell can be formed. That is, it is possible to provide an electrodeposition apparatus capable of forming an oxide film, which is optimal as a reflection layer having an effective light confinement effect of a solar cell, on a long substrate without unevenness, thereby improving efficiency. A high solar cell can be manufactured at low cost with high yield.

[Brief description of drawings]

FIG. 1 is a perspective view showing a first configuration example of an anode electrode according to the present invention.

FIG. 2 is a schematic view showing an example of a long substrate electrodeposition apparatus to which the present invention can be applied.

FIG. 3 is a perspective view showing a second configuration example of the anode electrode according to the present invention.

FIG. 4 is a perspective view showing a third configuration example of the anode electrode according to the present invention.

FIG. 5 is a perspective view showing a fourth configuration example of the anode electrode according to the present invention.

FIG. 6 is a schematic view showing an arrangement configuration example of anode electrodes according to the present invention.

[Explanation of symbols]

1001 Anode electrode 1002 Long substrate 1003 Substrate transport direction 1005 Anode width 1006 Anode length 1007 Substrate width 2001 Long substrate 2002 Substrate feeding roller 2003 Interleaf roll roller 2005 Tension detection roller 2006 Power feeding roller 2007, 2058 Stopper 2008 Power source 2009 Electrodeposition Tank 2062 Substrate winding rollers 2010-2012 Steam discharge ducts 2013, 2014, 2031, 2057, 2066
Support roller 2015 Power feeding bar 2016 Electrodeposition bath 2017 Anode 2018 Air blowing pipe 2019 Stirring air introduction pipe 2020 Electrodeposition bath liquid supply pipe 2021, 2022, 2038 to 2043 Valve 2023 Bath circulation pump 2024 Heater 2025 Electrodeposition circulation tank 2026 Steam Discharge duct 2027 Circulation pump 2029 Electro-folding preliminary tank 2030 Water washing tank 2032 First water washing tank 2033 Second water washing tank 2034 Third water washing tank 2035 to 2037 Supply pipe 2044 to 2046 Water circulation pump 2047 to 2049 Water washing circulation tank 2051 Warm air drying oven 2052 Warm air blowing pipe 2053 Warm air collecting pipe 2054 Filter 2055 Hot air generating furnace 2056 Outside air introducing pipe 2059 Meandering correction roller 2060 Interleaf paper feeding roller 2065 Air knife 3001 Anode electrode 3002 Long substrate 3003 Substrate transport direction 3005 Anode width 3007 Anode width 4001 Anode electrode 4002 Long substrate 4003 Substrate transport direction 4004 Anode facing surface 4005 Anode width 4006 Anode length 4007 Substrate width 5001 Anode electrode 5002 Long substrate 5003 Substrate transport direction 5004 Anode facing surface 5005 Anode width 5007 Substrate width 5008 Enclosure width 5009 Enclosure 6002 Long substrate 6003 Substrate transfer direction 6010 Power feeding roller 6011 Electron folding tank 6012 to 6019 Anode electrode 6020 to 6023 Power supply

Front Page Continuation (72) Inventor Toyamakami 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) Reference JP-A-9-92861 (JP, A) (58) Fields investigated (58) Int.Cl. ⁷ , DB name) C25D 17/00 C25D 9/04 C25D 17/10 C25D 17/12 C25D 21/00

Claims (9)

(57) [Claims] 1. An electrodeposition apparatus comprising an electrodeposition tank for forming an oxide film on a substrate by energizing the substrate and the anode electrode in an electrodeposition bath, wherein the anode electrodes have opposite widths. The width of the electrodeposition apparatus is set to be equal to or larger than the width of the electrodeposition apparatus. 2. The electrodeposition apparatus according to claim 1, wherein the anode electrode has a mesh structure. 3. The electrodeposition apparatus according to claim 1, wherein the anode electrode is made of zinc. 4. The electrodeposition apparatus according to claim 1, wherein the anode electrode is formed of a non-reactive metal. 5. The electrodeposition apparatus according to claim 1, wherein the anode electrode is covered with a dielectric enclosure. 6. The folding device according to claim 5, wherein the enclosure of the dielectric is set such that the enclosure width along the substrate width direction is equal to or larger than the width of the opposing substrate. . 7. The electrodeposition apparatus according to claim 5, wherein the dielectric is a fluororesin. 8. The electrodeposition apparatus according to claim 1, wherein the substrate is a long substrate. 9. The electrodeposition apparatus according to claim 1, wherein the electrodeposition apparatus is provided in a roll-to-roll device that carries a long substrate between rolls.