JP3517588B2 - Electrodeposition apparatus and its control method - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an electrodeposition apparatus for depositing an oxide thin film on a long substrate.

[0002]

2. Description of the Related Art The present applicant has previously proposed a method of depositing an oxide by utilizing an electrochemical reaction of an aqueous solution (hereinafter referred to as "electrodeposition method"), one of which is a long substrate. We proposed a method of electrodeposition on (roll substrate, web, hoop material, coil, tape, reel material). Here, the long substrate is a very thin rectangular thin plate that can be rolled up in the longitudinal direction and held in the form of a roll. The long substrate is an industrially extremely advantageous member because the operating rate and running cost can be reduced because continuous film formation can be performed.

A schematic view of an example of an electrodeposition apparatus for depositing an oxide on the above long substrate by an electrodeposition method is shown in FIG. Figure 2
As shown in FIG. 7, in the apparatus, a voltage is applied between the long substrate 2001 and the anode 2017 in the electrodeposition tank 2009 while depositing oxides from the electrodeposition bath 2016 in the electrodeposition tank 2009 while washing the water in the water washing tank 2030. After doing
Dry with warm air and roll up again.

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

(1) Unlike vacuum equipment such as sputtering,
Film deposition 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.

(2) In most cases, the running cost is low. The reason is that the sputtering requires manpower and equipment for producing the target, is expensive, and the utilization efficiency of the target is low at about 20% or less. Therefore, when the throughput of the apparatus must be increased or when the film thickness is large, the target replacement work will occupy a considerable weight.

(3) It is superior in terms of equipment and running cost to the CVD method and the vacuum deposition method other than sputtering.

(4) The waste liquid can be easily treated,
The impact on the environment is small and the cost for preventing environmental pollution is not high.

[0009]

As described above, as shown in FIG.
It is possible to deposit an oxide thin film on a long substrate at a very low cost by using an electrodeposition apparatus such as that described above. However, the present inventors actually operate the apparatus of FIG. 2 to perform electrodeposition. Where
There was unevenness in the location of the anode current. The causes are that the substrate is a catenary, the distance between each anode and the substrate is not always exactly constant, and the connection resistances at the portions connected to each anode are not equal. Therefore, when a plurality of power supplies corresponding to the number of anodes were prepared and the current was controlled to form a film, the film formation rate could be constant regardless of the location, and the unevenness of the entire film was effectively I was able to prevent it. However, if the power supplies are made independent, the control of each power supply may become unstable, and abnormal growth may occur in the obtained film.

An object of the present invention is to provide an electrodeposition apparatus that solves the above problems. Specifically, in an electrodeposition apparatus having a plurality of anodes and current sources, each current source is stably controlled. In order to efficiently deposit an oxide thin film having a uniform thickness.

[0011]

The first aspect of the present invention is an electrodeposition apparatus for depositing an oxide thin film on a long substrate,
It has a plurality of anodes and a plurality of current sources connected to the anodes and capable of independently controlling the current, and the return line of the power supply output of each current source branches from the common power feeding unit via a common power feeding unit. Each of the current sources has a short circuit having a short circuit switch, and a connection switch is provided on the path from the connection point between the short circuit and the current source output to the anode. Is an electrodeposition apparatus.

[0012] A second aspect of the present invention is a method for controlling the above-mentioned electrodeposition apparatus, in which, when performing the electrodeposition, the connection switch that communicates with an off current source is opened and the short-circuit switch is closed in advance. After turning on the current source and supplying current to the short circuit to stabilize the current source, the connection switch is closed and the short circuit switch is opened to supply current to the electrodeposition circuit. Is a control method.

A third aspect of the present invention is an electrodeposition apparatus for depositing an oxide thin film on a long substrate, comprising a plurality of anodes and a plurality of anodes connected to the anodes and capable of independently controlling current. Each current source has a power supply output return line branched from the common power supply unit and connected to an individual current source through a common power supply unit, and a current is supplied to the output side of each current source. The electro-deposition apparatus is characterized in that it is provided with a backflow prevention means.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The cause of the instability of current control solved by the present invention will be described. FIG. 3 is a diagram showing a configuration in which a current source is connected to each of a plurality of anodes in a conventional electrodeposition apparatus. In this figure, two anodes are shown for convenience, but three or more anodes may be connected in parallel and the basic mechanism of action is the same.

In FIG. 3, a long substrate 3001 is conveyed in a substrate conveying direction 3002, and an anode 3003 is formed.
And 3004 are placed at a predetermined distance in the electrodeposition bath. Each anode is an anode cable 300
It is connected to the output side of the current sources 3007 and 3008 via 5, 3006. In addition, the return of current from these current sources is performed from the long substrate 3001 to the power feeding roller 3009.
Through a return cable 3010 to the return of each current source.

An electrical equivalent circuit of FIG. 3 is shown in FIG. In the figure, reference numeral 4009 is a roller power feeding portion, and 4013 and 4014 are anode portions. Therefore, the substrate resistance 4001 is the resistance of the long substrate 3001 extending from the facing portion of the anode 3003 to the power feeding roller 3009, and the substrate resistance 4002 is the anode 3
The resistance of the long substrate 3001 from the facing portion of 004 to the facing portion of the anode 3003, the anode resistance 4003 is the resistance of the bath between the anode 3003 and the long substrate 3001 facing the anode, and the anode resistance 4004 is the anode 30.
04 and the long substrate 3001 facing the anode, the resistance of the bath, and the bath resistance 4015 is the anode 300 through the bath.
Resistance between 3 and 3004, anode cable resistance 40
05 is a current source 3007 (400
7) the resistance of the cable connected to the anode cable resistance 4006 from the anode 3004 to the current source 3008.
The resistance of the cable connected to (4008), the power feeding roller resistance 4010, the combined resistance of the roller contact power feeding resistance from the power feeding roller 3009 to the return line branch portion and the shared cable, and the individual return cable resistance 4011 from the return line branch portion. The cable resistance to the connected current source 3007 and the individual return cable resistance 4012 are the cable resistances from the return line branch portion to the connected current source 3008.

It is assumed that each resistance value is represented by R with each code as a subscript (for example, anode resistance 40
04 is R ₄₀₀₄ ), and the current from the current source 4007 is I
₄₀₀₇ , and the current from the current source 4008 is I ₄₀₀₈ . Using Kirchhoff's theorem, the anode resistance 40
Currents I ₄₀₀₃ and I ₄₀₀₃ and 4004, respectively.
₄₀₀₄ is shown by the following formulas, respectively.

[0018]

[Equation 1]

Further, the voltages V ₄₀₀₇ and V ₄₀₀ to be generated in order to cause currents to flow in the current sources 4007 and 4008, respectively.
₄₀₀₈ is shown by the following formula.

[0020]

[Equation 2]

Here, a specific resistance value is evaluated. When using 85 ° C., 0.02 M zinc nitrate as the electrodeposition bath,
The specific resistance of the bath is 14 Ωcm, and the resistance value of the anode resistances 4003 and 4004 based on this is about 70 mΩ. Further, the resistance of the long substrate of SUS is 2 mΩ per 1 m in length, the substrate resistance 4001 is about 6 mΩ, and the substrate resistance 4002 is about 1 mΩ. Furthermore, power supply roller resistance 4
010, anode cable resistors 4005 and 4006,
The individual return cable resistance 4011 is approximately 1 mΩ, and the individual return cable 4012 is approximately 2 mΩ. The bath resistance 4015 including the stray portion was about 10 mΩ.

On the basis of the above resistance value, the current value flowing through the anode resistance and the voltage [mV] of the current source are: I ₄₀₀₃ = 0.536I ₄₀₀₇ + 0.470I
₄₀₀₈ I ₄₀₀₄ = 0.464I ₄₀₀₇ + 0.530I
₄₀₀₈ V ₄₀₀₇ = 46.5I ₄₀₀₇ + 39.9I ₄₀₀₈ V ₄₀₀₈ = 39.9I ₄₀₀₇ + 47.6I ₄₀₀₈ .

For example, if I ₄₀₀₇ = I ₄₀₀₈ = 5A, then I ₄₀₃ = 5.03A, I ₄₀₀₄ = 4.9A.
7A, V ₄₀₀₇ = 0.432V, V ₄₀₀₈ = 0.4
It is 38V. Therefore, when the current sources 3007 and 3008 simultaneously discharge currents of 5 A each, the anode 3003,
The electrodeposition current of almost 5 A flows in 3004, and the current sources 3007 and 3008 flow 0.432 in order to flow the current.
Potentials of V and 0.438V appear at the current source output.

Next, let us consider a case in which the same equation is used to perform control so that only one current source supplies a current of 5A. I
_{When 4007} = 5A and I ₄₀₀₈ = 0A, I ₄₀₀₃
= 2.68A, I ₄₀₀₄ = 2.32A, V ₄₀₀₇ =
_0.233V, is a V 4008 = 0.200V. On the contrary, when I ₄₀₀₇ = 0A and I ₄₀₀₈ = 5A, I
₄₀₀₃ = 2.35A, I ₄₀₀₄ = 2.65A, V
₄₀₀₇ = _0.200V, a V 4008 = 0.238V. That is, when only one of the current sources 3007 and 3008 is turned on, a reverse voltage is applied to the other current source.

The presence of such a reverse voltage is a cause of unstable operation of the power supply, and the voltage between the current output terminals fluctuates due to on / off of another power supply, and R ₄₀₁₅ due to fluctuations in stray current, for example. Fluctuates and the voltage across the current output terminals fluctuates, which changes the reverse voltage, making the operation of the current source unstable and making it difficult to control the current source. The fluctuation of the stray current is caused by the movement of the electrodeposition bath due to the stirring air, the vertical movement of the substrate due to the stirring air, the change in the power supply resistance accompanying the substrate transportation, etc., and is therefore extremely difficult to predict.

More specifically, in the configuration shown in FIG. 3, for example, a reverse voltage is applied to the current source 3008 by the current source 3008 when only the current source 3007 is on. When the current source 3008 is turned on here, the current source 300
Since a reverse voltage is applied to the output of No. 8, it takes a long time to stabilize the output of the current source 3008. Moreover, as described above, the reverse voltage value easily fluctuates due to fluctuations in the stray current, so it is difficult to grasp and respond to an accurate value. Therefore, it is necessary to take measures in advance so that each current source is not affected by the reverse voltage.

The present invention prevents the reverse voltage from affecting the current source, stabilizes the output of the turned-on current source in a short time, and turns on / off a plurality of current sources individually for stable control. It is the one that made it possible. In the present invention, as a specific means for preventing the influence of the reverse voltage on the current source,
There are a short circuit in each current source and a configuration in which a connection switch is provided in a path leading to the anode, and a configuration in which a reverse voltage prevention unit is provided between the current source and the anode.

FIG. 1 is a schematic configuration diagram of the peripheral portion of the anode of the first embodiment of the electrodeposition apparatus of the present invention. In FIG. 1, 1001 is a long substrate, 1002 is a long substrate 1001.
Transport direction, 1003 and 1004 are anodes, 100
5 and 1006 are anode cables, 1007 and 10
Reference numeral 08 is a current source, 1009 is a feeding roller, 1010 is a return cable, 1011 and 1012 are individual return cables, 1020 and 1021 are connection switches, and 1022 and 1023 are short-circuit switches.

In FIG. 1, a long substrate 1001 is sent in a transport direction 1002 in an electrodeposition bath so as to face anodes 1003 and 1004, and an oxide is deposited on the substrate by a current from each anode to the substrate. Be punished. The current supply to the anodes 1003 and 1004 is performed via the connection switches 1020 and 1021 connected to one of the output terminals of the current sources 1007 and 1008, respectively. The other output terminals of the current sources 1007 and 1008 are connected to the individual return cables 1011 and 101, respectively.
2 to the return cable 1010. The current from the long substrate 1001 passes through the power feeding roller 1009, returns to the other of the output terminals of the current sources 1007 and 1008 through the individual return cables 1011 and 1012, and forms a current loop. A short circuit that bypasses these current loops and short-circuits both output terminals of the current sources 1007 and 1008 is formed.
22 and 1023 open and close the circuit.

Turning on / off of the current source in the above circuit will be described. In the current applied state during electrodeposition, the current source is on, the connection switch is closed, and the short-circuit switch is open. Now, when the current source is turned off, the connection switch is open, and the short-circuit switch is open, when shifting to the current application state, first, the short-circuit switch is closed while the connection switch is open to form a short-circuit circuit. The current source is turned on to enter a standby state in which current flows through the short circuit. Then, when the connection switch is closed, current also flows in the anode. further,
When the short-circuiting switch is opened, the short-circuiting circuit is cut off, and the current is applied only in the anode.

When the current is cut off from the current applied state, the standby state is passed. That is, after closing the short-circuit switch and passing a current through the short-circuit, the connection switch is opened and subsequently the current source is turned off. Here, after the current is cut off, the current source is off, the connection switch is open, and the short-circuit switch is closed. Therefore, when applying the current again, it is sufficient to turn on the current source. After that, it is not necessary to open the short-circuit switch.

By passing through the above-mentioned standby state, the current source for supplying current to the circuit in which a plurality of current sources influence each other, the current source once supplies current to the short-circuit circuit and then supplies current to the circuit. Therefore, the influence of the reverse voltage on the current source is prevented, and the current output from the current source in the circuit is stabilized in a short time. In addition, the current source in the ON state is cut off from the current circuit after the current has flowed through the short circuit after passing through the standby state, and when the circuit has an inductor component, a reverse voltage is applied and the current source is destroyed. Can be avoided.

In the above embodiment, when the plurality of current sources in the cut-off state are sequentially brought into the current application state, it is desirable to sequentially carry out the current sources closer to the power feeding roller. Also,
When sequentially shutting off the current source in the current applied state, it is desirable to shut off the current source farther from the power feeding roller.
The reason is that the current source closer to the power feeding roller is more affected by other current sources.

FIG. 5 is a schematic configuration diagram of the anode peripheral portion of the second embodiment of the electrodeposition apparatus of the present invention. In FIG. 5, reference numeral 5001 is a long substrate, and 5002 is a long substrate 5001.
Transport direction, 5003 and 5004 are anodes, 500
5 and 5005 are anode cables, 5007 and 50
08 is a current source, 5009 is a power feeding roller, 5010 is a return cable, 5011 and 5012 are individual return cables, and 5031 and 5032 are diodes.

In this embodiment, a diode is arranged as a reverse voltage preventing means between the anode and the current source. Since the influence from other current sources acts in the direction of canceling the output, the influence on the current sources is prevented by interposing the diode. According to the present embodiment, since the current source can be used without contact, the control means is simple, and since switches are not used, it is not necessary to consider their connection resistance and the change with time of resistance, and the electrodeposition apparatus As reliability is improved.

[Electrodeposition Apparatus] The overall structure of the electrodeposition apparatus of the present invention will be described with reference to FIG. Note that, although FIG. 2 shows a single structure for the anode current source for the sake of convenience, it is assumed that the present invention is controlled by a plurality of current sources as in the embodiment described above.

The long substrate 2001 is carried to the apparatus in the form of a coil wound on a bobbin. In this device, the coil is set on the substrate feeding roller 2002, and the interleaving paper wound for the surface protection is unwound by the interleaving paper winding roller 2003 while the substrate winding roller 2
It is conveyed toward 062. That is, the substrate 2001 enters the electrodeposition tank 2009 via the tension detection roller 2005 and the power feeding roller 2006. In the electrodeposition tank 2009, the support rollers 2013 and 2014 are positioned to perform electrodeposition. Next, it is sent to the washing tank 2030 and washed with water.
Positioning in the washing tank 2030 is performed by the support roller 203.
1 and 2066. Further warm air drying oven 2
It is dried in 051, the lateral deviation is corrected by the meandering correction roller 2059 after passing through the supporting roller 2057, and a new interleaving paper from the interleaving paper feeding roller 2060 is wound to protect the film formation surface, and is wound up by the substrate winding roller 2062. Is sent to the next step.

The tension detecting roller 2005 is the long substrate 20.
By detecting the dynamic winding tension of 01, feedback is applied to a braking means such as a powder clutch (not shown) linked to the shaft of the substrate feeding roller 2002 to keep the tension constant. As a result, the long substrate 2001
Is designed so that the conveyance path of the roller has a predetermined value between the support rollers. In particular, in the apparatus of FIG. 2, since the roller does not touch the film-forming surface, if the tension is weak, the long substrate 2001 may come off the supporting roller, or the electrodeposition tank 20 may be removed.
09, and the long substrate 2001 hangs down at the entrance / exit of the washing tank 2030, rubbing the film-forming surface and causing scratches. The device configuration in which the film-forming surface does not touch has the advantage that the film-forming surface is not damaged or soiled.In particular, micron-sized irregularities are formed on the thin film like the reflective layer of a solar cell. Preferred for applications where it must be.

The feeding roller 2006 is a long substrate 2001.
For applying a potential on the cathode side to the cathode, and is installed as close to the electrodeposition bath 2016 as possible, and is equipped with a power source 2008.
It is connected to the negative side of.

The electrodeposition tank 2009 holds the electrodeposition bath 2016, determines the path of the long substrate 2001, and installs the anode 2017 on the path of the long substrate 2001.
7, a positive potential is applied from the power source 2008 via the power feeding bar 2015. As a result, an electrochemical electrolytic deposition process in which the long substrate 2001 is negative and the anode 2017 is positive in the electrodeposition bath 2016 proceeds. Electrodeposition bath 201
When 6 is kept at a high temperature, the amount of steam generated is considerably large, so that steam is allowed to escape from the discharge ducts 2010-2012. Further, in order to stir the electrodeposition bath 2016, air is introduced from a stirring air introduction pipe 2019,
Air is bubbled from an air blowing pipe 2018 in the electrodeposition tank 2009.

In order to replenish the electrodeposition bath 2009 with a high temperature electrodeposition bath solution, an electrodeposition circulation tank 2025 is provided, and a heater 2024 is installed therein to heat the electrodeposition bath, and the bath solution is bathed. It is supplied from the liquid circulation pump 2023 to the electrodeposition bath 2009 through the electrodeposition bath liquid supply pipe 2020. The electrodeposition bath solution overflowing from the electrodeposition tank 2009 or the bath solution for returning a part positively 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, as shown in FIG. 2, valves 2021 and 2022 are used to form the electrodeposition circulation tank 202.
It is possible to control the supply amount of the bath liquid from 5 to the electrodeposition tank 2009. That is, when increasing the supply amount, the valve 202
1 is more open and valve 2022 is more closed.
When reducing the supply amount, the reverse operation is performed. Electrodeposition bath 2
The holding water level of 016 is adjusted by adjusting this supply amount and the return amount (not shown).

A circulation pump 20 is provided in the electrodeposition circulation tank 2025.
A filter circulation system including a filter 27 and a filter is provided so that particles in the electrodeposition circulation tank 2025 can be removed. When the supply / return between the electrodeposition circulation tank 2025 and the electrodeposition tank 2009 is sufficiently large, a sufficient particle removing effect can be obtained by installing a filter only in the electrodeposition circulation tank 2025 as described above. be able to.

In the apparatus shown in FIG. 2, the electrodeposition circulation tank 2
025 also has a steam discharge duct 2026 installed,
The structure is such that water vapor is discharged. In particular, since a heater 2024 is installed in the electrodeposition circulation tank 2025 as a heating source, steam is remarkably generated, and when it is not desirable that the generated steam is inadvertently released or condensed, It is extremely effective.

The electrodeposition 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, and once the electrodeposition bath 2016 of the electrodeposition tank 2009 is changed. In addition to holding the electrodeposition tank 2009, the electrodeposition tank 2009 is emptied to improve work efficiency.

Long substrate 2 after electrodeposition in the electrodeposition tank 2009
Next, 001 enters the washing tank 2030 and is washed with water.
In the washing tank 2030, the long substrate 2001 is positioned by the supporting rollers 2031 and 2066, and the first washing tank 203
2. The second washing tank 2033 and the third washing tank 2034 are sequentially passed. The washing circulation tanks 2047 to 2049 and the water circulation pumps 2044 to 2046 are arranged respectively, and two valves, that is, valves 2038 and 2041, or 2039 and 2042, 2040 and 2043 determine the amount of water to be supplied to the washing tank 2030. Wash water is supplied to the washing tanks 2032 to 2034 through the pipes 2035 to 2037. The method of controlling the water supply amount by the two valves is the same as the method of controlling the bath liquid supply amount in the electrodeposition tank 2009. Further, similarly to the electrodeposition tank 2009, it is possible to return the return water (not shown), which collects overflow or positively returns a part thereof, to the respective washing circulation tanks 2050.

Normally, in the three-stage water washing system as shown in FIG. 2, the water washing tank on the upstream side of the substrate transfer, that is, the first water washing tank 2
From 032, the downstream washing tank, that is, the third washing tank 2034
Purity of washing water becomes higher toward. This means that the cleanliness of the long substrate 2001 increases as the long substrate 2001 is transported and the process comes to the end. This means that as shown in FIG. 2, the washing water is first supplied to the third washing circulation tank 2049, and then the washing water overflowing in the third washing circulation tank 2049 is supplied to the second washing circulation tank 2
048, and by further supplying the wash water overflowing in the second water washing circulation tank 2048 to the first water washing circulation tank 2047,
This can be achieved by significantly reducing the amount of water used.

The long substrate 2001 which has been washed with water is drained by an air knife 2065 provided in a part of the water washing tank 2030, and then transferred to the warm air drying furnace 2051. Here, the drying is performed with convection air having a temperature sufficient to dry the water. Convective air for that purpose removes dust from the hot air generated in the hot air generating furnace 2055 through the filter 2054, and blows it out from the hot air introducing pipe 2052 to supply the hot air. The overflowing air is collected from the side 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 2055. The conveyance path of the long substrate 2001 in the warm air drying oven 2051 is the support roller 2066.
And the support roller 2057.

The meandering correction roller 2059 is used for the long substrate 2.
This is an object to be wound around the substrate winding roller 2062 by correcting the widthwise deviation of 001, and the amount of deviation is detected by a sensor (not shown), and the meandering correction roller 2059 is controlled by rotating it using an arm (not shown) as a fulcrum.
The deviation detected by the normal sensor is also corrected by the meandering correction roller 2.
The operation amount of 0592 is also extremely small and does not exceed 1 mm. Even when the long substrate 2001 is wound up, new interleaving paper is supplied from the interleaving paper feeding roller 2060 for surface protection.

Stopper 2007 and stopper 2058
Simultaneously work to make the long substrate 2001 stand still while the transport tension is applied. Thereby, the long substrate 2
Workability can be improved during replacement of 001 and maintenance of the apparatus.

Next, details of the apparatus of the present invention and members used for electrodeposition according to the present invention will be described.

[Long Substrate] As the material of the long substrate used in the present invention, any material can be used as long as it has electrical continuity on the film-forming surface and is not affected by the electrodeposition bath. For example, SUS, Al, Cu , Fe, Cr and other metals are used. PET with metal coating
Film etc. are also available. Among these, SUS is relatively inexpensive and has excellent corrosion resistance and is excellent as a long substrate for performing a photovoltaic device formation process in a later step.

The substrate surface may be a polished mirror surface or a smooth surface such as BA. Also, a rough surface represented by 2D may be used.

Further, another conductive material may be formed on the substrate, which is selected according to the purpose of electrodeposition.

In the case of a long substrate made of SUS or Cr, since the specific electric resistance is larger than that of other metals, the reverse voltage to the current source becomes large, and the present invention is particularly effective.

[Oxide thin film] The oxide deposited in the electrodeposition apparatus of the present invention includes:
For example, zinc oxide can be mentioned. In particular, examples of the zinc oxide film include a c-axis oriented zinc oxide polycrystalline film and a c-axis inclined zinc oxide polycrystalline film, which are constituent members of the photovoltaic element. Further, an indium oxide film or the like deposited from indium nitrate is also suitably formed by the electrodeposition apparatus of the present invention.

[Electrodeposition Bath] The electrodeposition bath of the present invention is selected according to the desired oxide thin film. For example, when depositing a zinc oxide film having irregularities of about the wavelength of light effective as a light confining reflection layer of a photovoltaic element, zinc nitrate having a concentration of 0.01 M or more is used. Moreover, in order to obtain a zinc oxide film oriented in the c-axis,
Although it depends on the substrate, it is generally preferable to set it to 0.05 M or less. In either case, the sugars added are preferably 3 g / l or more for sucrose and 0.01 g / l or more for dextrin. The temperature of these electrodeposition baths is preferably 60 ° C. or higher in order to prevent metal precipitation. Especially 80
℃ or more is desirable.

[Anode] The anode of the electrodeposition apparatus of the present invention refers to an anode having a positive potential with respect to the substrate and allowing an electrodeposition current to flow toward the substrate. Usually, as shown in FIG. 2, it is arranged so as to face and be close to the substrate. In the present invention, a plurality of anodes are used, and each of these anodes or a plurality of anodes are current-controlled by a current source that prevents the influence of reverse voltage as described above.

In the present invention, the size of the anode in the widthwise direction of the long substrate (anode width) is equal to the width of the long substrate, or
Alternatively, it is set larger than that. This is because when the width of the anode is shorter than the length of the long substrate, unevenness of the oxide thin film in the substrate width direction occurs. In particular, since the electrodeposition apparatus of the present invention deposits an oxide thin film, it is necessary not only to carry metal ions by an electric field but also to advance an oxidation reaction in the vicinity of a substrate, and therefore, to maintain the oxidation reaction. The potential (potential between the solution and the substrate) must be secured,
It seems that a different approach from metal plating is needed.

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,
Oxide deposition by the electrodeposition apparatus of the present invention shows opposite characteristics. Furthermore, in experiments in a glass beaker, sufficient deposition 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 distance between the anode and the substrate has the greatest mechanical precision, but is preferably 1 mm or more and several tens of cm or less, and more preferably 10 mm to 50 mm.
Place it around mm. Further, it is preferable that the anodes to which the same electric potential is applied are arranged at the same distance (arranged as parallel to the substrate as possible).

The size of the anode in the substrate transport direction is 0.
It can be appropriately selected from about 1 mm to 1 m or more, and the shape thereof can be plate-like, cotton-like, rod-like, mesh-like or lattice-like. Both are determined by the ease of mechanical assembly and the ease of holding the potential.

In the present invention, a plurality of anodes are arranged in order to match the distance to the carrier substrate that draws the catenary line, and therefore a plurality of anodes are arranged. At this time, the potential and shape of each anode do not have to be the same. For example, in the case of a film with a large deposition rate on the side closer to the substrate but a large deposition rate, and a film with a large deposition rate on the side far from the substrate and a low deposition rate, the anode in the first half of the process should be placed closer or at a higher potential It is set such that the electrodeposition current is increased by keeping it high and the anode in the latter half of the process is further separated or the potential is kept lower to reduce the electrodeposition current. In that case, it is also possible to select a plate-shaped anode in the first half and a rod-shaped anode in the second half.

[Cable] As the cable used in the electrodeposition apparatus of the present invention, a usual covered wire or bare wire can be used. However, in order to reduce the line resistance, it is preferable to use one having a sectional area of 14 mm ² or more. 1mm for wire rods with a cross-sectional area of 14 mm ² or more
If a wire having a resistance value of 2 Ω / km is used for 10 m, 10
It will have a cable resistance of mΩ to 20 mΩ. In order to further reduce the resistance value, it is preferable to use a cable having a large wire diameter or a short cable to make the resistance smaller than this value.

[Switch] The switch used in the electrodeposition apparatus of the present invention is a switch that opens and closes a circuit sufficiently effectively, has a mechanical contact, a relay contact, and a solid state relay (SS).
R) types are available. However, in all cases, it is necessary to pay attention to the contact resistance, and the contact resistance should be as small as possible.

[Feeding Unit] The feeding unit used in the electrodeposition apparatus of the present invention is capable of efficiently obtaining an electric current from the substrate, and may be a driven roller, a sliding brush or the like made of SUS, copper, carbon or the like. Available. In order to reduce the power supply resistance, the tension on the roller may be increased or the electrolytic solution may be flowed.

[Current Source] The current source used in the electrodeposition apparatus of the present invention is capable of controlling the inter-terminal current and has a capacity capable of realizing the terminal voltage. Also, the output terminals of each other are floating from the ground and can be controlled independently. A commonly available DC current source that satisfies the capacity can be generally used. Further, in the present invention, since the influences exerted by the current sources are prevented, it is not necessary to use a bipolar power source having a so-called suction function. For this reason,
A very low cost power supply can be used.

[0067]

[Example] [Example 1] An apparatus incorporating the configuration of Fig. 1 was constructed as an anode part of the electrodeposition apparatus of Fig. 2. 6 with current source for each
The two anodes were arranged in parallel as shown in FIG.

In this example, the electrodeposition bath was 0.0
The one containing 05M zinc nitrate and 0.07 g / l dextrin was used. The film deposition temperature was 85 ° C., and the conductivity was measured and found to be 1 mS. Each of the anodes had a length of 420 mm and a width of 360 mm, and was opposed to a long substrate having a width of 350 mm at a distance of 1 cm. The anode resistance of the electrodeposition bath is approximately 0.7Ω, and after this,
A current flowed from each anode to the long substrate. The bath resistance (corresponding to R ₄₀₁₅ in FIG. 4) was 3Ω.

As the long substrate, SUS430 having a width of 350 mm and a thickness of 0.15 mm was used. The resistance of this substrate was 0.02 Ω / m. The resistance of the power feeding part was 0.01Ω. The resistances of the cables do not exceed 1 mΩ, and the actual cable resistance can be ignored in this embodiment.

When the voltage applied to each current source is evaluated using the above resistance value and the above mathematical expression, V ₄₀₀₇ = 0.659I ₄₀₀₇ + 0.183I
₄₀₀₈ V ₄₀₀₈ = 0.183I ₄₀₀₇ + 0.666I
It becomes ₄₀₀₈ . The unit is [A] or [V]. Incidentally, here 2
I evaluated the case with two anodes and a current source,
The basic idea and order of values are the same.

As described above, the current source on the side closer to the power feeding roller is more affected by the current source on the far side. Therefore, when the current source capacity is not sufficient, this effect appears as instability in current control.

In this embodiment, first, all current sources,
The short-circuit switch and connection switch were controlled simultaneously by the interlocking switch.

When the short-circuit switches of all current sources were fixed to open and the connection switches were fixed to closed, and the current sources were turned on to perform electrodeposition, the current was unstable at the beginning of electrodeposition.
It took 30 seconds to stabilize. On the other hand, in accordance with the control method according to the present invention, once the short-circuit switch was closed, the current source was turned on to put it in a standby state, and then the connection switch was closed to perform electrodeposition, and it was stable within 3 seconds. The period has been reached. Further, no abnormal growth occurred during the film deposition.

Next, each current source, the short-circuit switch, and the connection switch are individually controlled. When the current source is turned on, the current source closer to the power feeding roller is turned on, and when it is turned off, the current source far from the power feeding roller is supplied. I tried to turn it off. As a result, almost no initial fluctuation was observed when the current source was turned on, and an oxide film without abnormal growth and excellent in uniformity was obtained. By individually controlling each current source in this manner, it is possible to efficiently prevent a process variation and a current source variation associated with the turning on / off of a current.

Example 2 An apparatus incorporating the configuration of FIG. 5 was constructed as the anode part of the electrodeposition apparatus of FIG. The same electrodeposition bath and substrate as in Example 1 were used. Therefore, the influence between the current sources is the same as in the first embodiment.
Is about the same.

In this example, it took less than 5 seconds after the current source was turned on until the current became stable. Further, as in Example 1, abnormal growth did not occur during film deposition.

[0077]

As described above, according to the present invention,
In the electrodeposition process that controls the current flowing between multiple anodes and the substrate using multiple current sources, the influence of the current sources on each other is reduced, abnormal growth of oxide film is prevented, and a uniform oxide film is formed. Obtainable.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an anode peripheral portion of a first embodiment of an electrodeposition apparatus of the present invention.

FIG. 2 is a schematic configuration diagram for explaining the overall configuration of the electrodeposition apparatus of the present invention.

FIG. 3 is a schematic configuration diagram of a peripheral portion of an anode of a conventional electrodeposition apparatus.

FIG. 4 is a diagram showing an electrical equivalent circuit of the configuration of FIG.

FIG. 5 is a schematic configuration diagram of an anode peripheral portion of a second embodiment of the electrodeposition apparatus of the present invention.

[Explanation of symbols]

1001, 3001, 5001 Long substrate 1002, 3002, 5002 Substrate transport direction 1003, 1004, 3003, 3004, 5003
5004 Anode 1005, 1006, 3005, 3006, 5005
5006 Anode cables 1007, 1008, 3007, 3008, 4007,
4008,5007,5008 Current source 1009,3009,5009 Power feeding roller 1010,3010,5010 Return cable 1011,1012,3011,3012,5011,
5012 Individual return cables 1020, 1021 Connection switches 1022, 1023 Short circuit switch 2001 Long substrate 2002 Substrate feeding roller 2003 Interleaving paper winding roller 2005 Tension detection roller 2006 Power feeding roller 2007, 2058 Stopper 2008 Power source 2009 Electrodeposition tank 2010, 2011, 1212 2026 Steam discharge duct 2015 Power supply bar 2016 Electrodeposition bath 2017 Anode 2018 Air blowing pipe 2019 Stirring air introduction pipe 2020 Electrodeposition bath liquid supply pipe 2021, 2022, 2028, 2038 to 2043
Valve 2023 Bath liquid circulation pump 2024 Heater 2025 Electrodeposition circulation tank 2027 Circulation pump 2029 Electrodeposition preliminary tank 2030 Water washing tank 2013, 2014, 2031, 2057, 2066
Support roller 2032 First washing tank 2033 Second washing tank 2034 Third washing tank 2035-2037 Water supply pipe 2044-2046 Water circulation pump 2047 First washing circulation tank 2048 Second washing circulation tank 2049 Third washing circulation tank 2050 Water washing circulation tank 2051 Warm air drying oven 2052 Warm air introducing tube 2053 Warm air collecting tube 2054 Filter 2055 Hot air generating furnace 2056 Outside air introducing tube 2059 Meandering correction roller 2060 Interleaf sheet feeding roller 2062 Substrate winding roller 2065 Air knife 4001,4002 Substrate resistance 4003,4004 Anode Resistance 4005, 4006 Anode cable resistance 4010 Power supply roller resistance 4011, 4012 Individual return cable resistance 4013, 4014 Anode part 4015 Bath resistance 5031, 5032 Diode

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Toyama Kamata 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) References JP-A-9-92861 (JP, A) JP-A-63 -293200 (JP, A) JP-A-61-204397 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C25D 9/04 C25D 21/00

Claims (7)

(57) [Claims] 1. An electrodeposition apparatus for depositing an oxide thin film on a long substrate, comprising a plurality of anodes and a plurality of current sources connected to the anodes and capable of independently controlling the current,
The return line of the power supply output of each current source is branched from the common power feeding unit via a common power feeding unit and connected to each current source, and each current source has a short circuit having a short circuit switch. An electrodeposition apparatus, wherein a connection switch is provided on the path from the connection point between the short circuit and the current source output to the anode. 2. The method for controlling an electrodeposition apparatus according to claim 1, wherein, when performing electrodeposition, the current switch is connected in advance to an off current source and the short-circuit switch is closed. After turning on the power source and supplying a current to the short circuit to stabilize the current source, the connection switch is closed and the short circuit switch is opened to supply a current to the electrodeposition circuit. Control method. 3. The method for controlling an electrodeposition apparatus according to claim 2, wherein the ON operation of the plurality of current sources is sequentially performed from the current sources close to the power feeding section. 4. When turning off the on-state current source, the short-circuit switch is closed to supply current to the short-circuit circuit, and then the connection switch is opened to shut off the current source from the electrodeposition circuit to turn off the current source. The method for controlling an electrodeposition apparatus according to claim 2, which is turned off. 5. The method for controlling an electrodeposition apparatus according to claim 4, wherein the turning-off operation of the plurality of current sources is sequentially performed from a current source farther from the power feeding section. 6. An electrodeposition apparatus for depositing an oxide thin film on a long substrate, comprising a plurality of anodes and a plurality of current sources connected to the anodes and capable of independently controlling currents,
The return line of the power supply output of each current source is branched from the common power feeding unit via a common power feeding unit and connected to each current source, and a current backflow prevention means is provided on the output side of each current source. An electrodeposition apparatus characterized in that 7. The electrodeposition apparatus according to claim 6, wherein the current backflow prevention means is a diode.