JP2008025030A - Method and apparatus for handling flat and fragile substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus by which an electrochemical treatment undesirable for a contact device, particularly the metallization of the contact device is largely reduced. <P>SOLUTION: In the method and the apparatus for treating the flat and fragile substrate (2), one or more substrates (2) are passed through a bath solution (14) in a horizontal state. In such a case, the contact surface of the substrate (2) is brought into contact with the contact device (7) to have potential different from that of a counter electrode (5) arranged in the bath solution (14). At least one blowing or aspirating device (11) is provided to prevent the undesirable deposition of the metal on the contact device (7). The blowing or aspirating device freely blows a treating liquid (14) onto a contact area between the contact device (7) and the substrate (2) or aspirates the solution therefrom. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention is a method for processing flat fragile substrates, particularly for the semiconductor and solar energy industries, comprising:
The substrate is guided through the bath liquid in a horizontal pass, and at least one contact surface of the substrate is brought into contact with the contact device in a horizontal pass to a potential that is distinct from the potential of the counter electrode disposed in the bath liquid. Method and
An apparatus for processing flat fragile substrates, particularly for the semiconductor and solar energy industries,
a) a bath container filled with the treatment liquid up to the specified liquid level;
b) a transport device capable of guiding the substrate through the bath liquid in a horizontal passage;
c) a processing power supply;
d) at least one contact device that can be brought into contact with at least one contact surface attached to the substrate and then couples the contact surface with one pole of the processing power source;
e) relates to a device having at least one counter electrode arranged in the processing liquid and coupled to the other pole of the processing power supply.

  In the semiconductor and solar energy industries, a very wide variety of wet processes are applied to very flat and thin substrates such as silicon disks (wafers), silicon plates and glass plates. Of particular interest in the context of the present invention is the electrochemical treatment of such substrates. In this process, the substrate is electrically contacted and electrolyzed, for example, cleaned, electroplated or etched. In the case of electrochemical treatment, the substrate surface can be switched to the cathode or the anode. Due to electroplating, the substrate surface is always polarized to the cathode and to the anode for etching and cleaning.

  In this case, in general, only one side of the flat substrate pointing downwards is processed during passage in the bath liquid in which the counter electrode is also arranged, while the contact is made via the side contact surface pointing upwards of the substrate. Is called. In this case, the contact surface is contacted by a contact device coupled to the pole of the processing power source. In this case, the problem arises that the contact device itself is subjected to an undesired electrochemical treatment, i.e. for example also particularly electroplated.

  Roller contact is known from US Pat. The contact devices described in these documents sometimes have to be metal removed and are expensive. For example, in the case of gold plating, the metal removal of the contact device is difficult or completely impossible. Metal removal by electrolysis of the contact device is therefore not possible and is described in US Pat. Rather, the contact device must in this case be replaced periodically. With known equipment, this needs to be done for approximately 12-24 hours. This wastes a lot of time and results in very long downtime of the production plant.

Furthermore, from patent document 4, a method for treating one side of the substrate surface in a horizontal passage is known. In this method, only the lower side of the passing substrate is moistened, and in some cases, the outer upper edge is still moistened. In practice, however, with a precisely flat substrate, this is very difficult or impossible to implement in the first place if the substrate is small and curved.
German Patent No. 196 28 784 A specification German Patent No. 196 33 797 A Specification European Patent 0 578 699 B1 Specification International Publication No. 2005/093 788 A1 Pamphlet

  The object of the present invention is to provide a method and a device of the kind mentioned at the outset, in which the undesired electrochemical treatment of the contact device, in particular the metallization of the contact device, is largely reduced.

  The above problems addressed by the present method are solved by free spraying or drawing of bath liquid from the contact area between the contact device and the substrate.

  According to the present invention, that is, the substrate is completely immersed in the bath liquid, unlike the prior art, but is only immersed in a relatively short distance below the surface of the bath liquid. In this case, it is also possible to largely separate the contact device in the dynamic process from the bath liquid using a spraying or suction device. In this case, there is little or no contact between the contact device and the bath liquor, so that the undesired reaction between the contact device and the bath liquor will also take place only very limitedly. Not too much.

  If the presence of oxygen in the air does not cause a problem as a free blowing gas, air can be used most easily.

  However, in many cases, the bath liquid is sensitive to oxygen in the air, so an inert gas, preferably nitrogen, is used as the gas.

  By the measures of the present invention described above, undesirable electrochemical changes in the contact device, in particular metallization, can be largely avoided and in any case can be significantly reduced. If the remaining obstructive change of the contact device remains, especially metallization, a method variant can be selected, in which the path of movement of the substrate is tracked and the contact device is contacted with the contact surface of the substrate. Only during the time in contact with the substrate is the potential required to process the substrate applied to at least one contact device. In this way, the time during which undesirable electrochemical action can be performed on the contact device is significantly reduced.

  In many electrochemical processes, the reaction can be reversed by polarity reversal. In this case, during a period when the contact device is not in contact with the contact surface of the substrate, a second potential that is suitable for reversing the reaction that proceeds during the treatment with the first potential is applied to the at least one contact device. The method can be implemented as is. In the case of metallization, this means that during the time when the contact device does not abut the contact surface of the substrate, metal deposition in the contact device is brought about by selection of the corresponding potential in the solution. In this way, the service life of the contact device can be further extended.

The above-mentioned issues addressed by the device are:
f) The solution is provided by attaching at least one spraying or suction device to the at least one contact device so that the contact area between the contact device and the contact surface of the substrate can be freely sprayed or sucked. Is done.

  An advantageous development of the device according to the invention is indicated in claim 9 or 10. The advantages of the devices according to the invention and their developments correspond to the advantages already mentioned above on the method according to the invention and its various variants.

  Embodiments of the present invention will be described in detail below with reference to the drawings.

To manufacture the solar cell, a silicon plate about 0.2 mm thick with thin metal electrical conductor rows deposited on the side that later becomes the active side for the sun is used. These conductor tracks must be reinforced by electroplating to a layer thickness of 1-20 μm. The reinforcing material can be copper, tin, silver or gold. On the opposite side of the substrate, there are contact surfaces required for this, for example in the form of contact strips and / or contact windows, which contact conductors are deposited on the “sun-active” side. And are electrically coupled.

  FIG. 1 shows an apparatus, generally designated by reference numeral 1, which can reinforce the deposited conductor track of such a silicon substrate. FIG. 1 shows three such silicon substrates, denoted by reference numerals 2a, 2b and 2c. These silicon substrates 2a, 2b and 2c are guided through the electroplating bath solution 14 using a roller transport system including a plurality of driven rollers 3a, 3b, 3c and 3d. The direction of transport is indicated by arrow 4.

  The liquid level 15 of the bath liquid 14 is located close to and above the upper side of the silicon substrates 2a, 2b and 2c, for example, 0.1 to 10 mm. The silicon substrates 2a, 2b and 2c are completely immersed in the bath solution, i.e. during penetration through the electroplating bath.

  In this case, the “active to the sun” side surface provided with the conductor rows of the silicon substrates 2a, 2b and 2c points downward, and the side surface with the contact surface of the silicon substrates 2a, 2b and 2c points upward.

  A plate-like anode 5 coupled to the positive electrode of the electroplating current source 6 extends below and along the movement path of the silicon substrates 2a, 2b and 2c. When copper, tin or silver is targeted with a reinforced metal, a soluble consumed anode 5 can be used. However, when a gold bath is intended, an insoluble anode 5 is used.

  The conductor paths to be reinforced of the silicon substrates 2a, 2b and 2c must be at the cathode potential. This is done using contact rollers 7a, 7b, 7c and 7d, which are arranged on the sides of the silicon substrates 2a, 2b and 2c facing the transport rollers 3a, 3b, 3c and 3d, and It is pressed against the upward pointing side with the contact surfaces of the silicon substrates 2a, 2b and 2c, preferably with very little pressure, preferably elastically spring. Each of these contact rollers 7a, 7b, 7c and 7d is coupled to the negative pole of the electroplating current source 6 via controllable electronic switches 8a, 8b and 8c. The electronic switches 8a, 8b, 8c and 8d receive their control signals from the machine control unit 9, and the electronic switches can be opened or closed again by these signals.

  A sensor 10 is arranged in front of the first contact roller 7a as seen in the transfer direction 4, which can detect the passage of the front and rear edges of the various silicon substrates 2a, 2b and 2c passing by. The sensor 10 transmits these time points of the machine control unit 9. The machine controller can always calculate the exact position of all the silicon substrates 2a, 2b and 2c in the electroplating bath based on the moving speed of the silicon substrates 2a, 2b and 2c and the geometric data of the equipment. In particular, the machine control 9 therefore detects which of the contact rollers 7a, 7b, 7c and 7d is in electrical contact with the contact surfaces of the silicon substrates 2a, 2b and 2c and which is not in contact. it can. The machine control 9 functions so that only the electronic switches 8a, 8b and 8d in which the corresponding contact rollers 7a, 7b and 7d are just in contact with such contact surfaces are closed for reasons that will still become apparent later. . On the other hand, the electronic switch 8c in which the corresponding contact roller 7c is not in contact with the contact surfaces of the silicon substrates 2a, 2b and 2c is opened.

  As seen in the transfer direction 4, spray devices 11a, 11b, 11c and 11d are arranged in front of the respective contact rollers 7a, 7b, 7c and 7d. As best understood from FIG. 2, the spray device 11 has the shape of a tubular spray nozzle, which can be supplied with gas under pressure in the direction of arrow 12 and in the direction of arrow 13. In addition, gas is added to the region on the upper side of the silicon substrate 2 in the vicinity of the corresponding contact roller 7.

  Before entering the facility 1, the silicon substrates 2a, 2b and 2c are prepared as described above. That is, by depositing on the “active to the sun” side, a very thin metal conductor track is provided on the silicon substrate. Contact surfaces are attached to the opposing side surfaces of the silicon substrates 2a, 2b and 2c, and are coupled to the metal conductor paths. Next, the silicon substrates 2a, 2b and 2c are mounted on a transport roller system, which is guided through the narrow slits in the housing wall (not shown) of the device 1 on both sides.

  Next, the path of the substrate 2 is tracked through the facility 1.

  The substrate 2 enters the electroplating bath through the previously described housing slit below the bath liquid level 15. When the leading edge of the substrate passes the sensor 10, the sensor transmits the relevant time point to the machine control unit 9. At this point, the electronic switches 8a, 8b, 8c and 8d of all the contact rollers 7a, 7b, 7c and 7d are still open, so that no voltage is applied to the contact rollers 7a, 7b, 7c and 7d. No metal deposit is formed on the contact roller.

  The machine control unit 9 determines whether the contact roller 7 a is a silicon substrate 2 based on the moving speed of the silicon substrate 2 known to the machine control unit and the distance between the sensor 10 and the first contact roller 7 a in the transfer direction 4. Calculate the point of contact with the contact surface. At this point, the machine control unit 9 closes the electronic switch 8a. As a result, the potential of the contact roller 7a is provided, and the strengthening process by electroplating can be started.

  As shown in FIG. 2, the spraying device 11a attached to the first contact roller 7a freely sprays the bath liquid 14 onto the region near the contact roller 7a on the side surface located above the silicon substrate 2. As a result, even at this time, the contact roller 7a is hardly metalized despite the applied voltage. On the other hand, since the side surface of the silicon substrate 2a pointing downward with the conductor path to be reinforced is completely in the bath solution 14, a desired strengthening step by electroplating can be performed in the bath solution.

  Meanwhile, the sensor 10 detects the passage of the rear edge in the moving direction of the silicon substrate 2a, and transmits this to the machine control unit 9. Based on the known data, the machine control unit newly calculates the point in time when the contact surface of the silicon substrate 2a passes through the contact roller 7a, and shuts off the current supply to the contact roller 7a by opening the switch 8a.

  The same process is repeated in the area of contact rollers 7b, 7c and 7d.

  In practice, it is natural that not only one individual silicon substrate 2a passes through the device 1. Rather, as shown in FIG. 1, many silicon substrates 2a, 2b and 2c are transported through the apparatus 1 at relatively small intervals. The electronic switches 8a, 8b, 8c and 8d are opened and closed in the same way. In the embodiment shown in FIG. 1, the contact roller 7a of the first silicon substrate 2a is brought into contact with the substantially center of the contact surface, so that the corresponding switch 8a is closed. In the case of the second silicon substrate 2b, the corresponding contact roller 7b is already in the area of the rear contact surface in the direction of movement, and the corresponding switch 8b is still closed. However, the third contact roller 7c is not in contact with the contact surfaces of the silicon substrates 2a, 2b and 2c, and as a result, the corresponding switch 8c is opened.

  Although there is no silicon substrate in the vicinity of the third contact roller 7c, the corresponding spraying device 11c operates. This spraying device sprays into the bath liquid 14 with the lower region of the contact roller 7c without making contact with the bath liquid 14 to create a "Dell". That is, it may not be necessary to open the switch 11d. However, this opening provides an additional safety measure, probably because the splash of bath liquid 14 reaches the contact roller 7c.

  In FIG. 1, the fourth contact roller 7d in the moving direction is in the first region of the contact surface of the silicon substrate 2c existing there. The corresponding electronic switch 8d is therefore closed.

  As long as this allows the chemistry of the respective steps, air can be easily used as the gas supplied to the spraying devices 11a, 11b, 11c and 11d. However, as long as the electroplating bath is sensitive to oxygen in the air, nitrogen is selected as the gas. In this case, the air is sucked inside the housing of the device 1 and supplied to the spraying devices 11a, 11b, 11c and 11d by a blower used for the circulation operation. The entire process chamber is placed under a small nitrogen overpressure, which prevents oxygen from entering the ambient air.

  Instead of the simple tubular spraying devices 11a, 11b, 11c and 11d, a venturi nozzle can also be used. In these methods, the gas moved by the blower can be concentrated with ambient gas, which increases the total amount of gas and increases efficiency.

  The outlet openings of the spraying devices 11a, 11b, 11c and 11d need not be circular. Rather, the outlet opening can also be formed as a ring surrounding the corresponding contact rollers 7a, 7b, 7c and 7d.

  Finally, instead of spraying, the periphery of the side surface of the contact rollers 7a, 7b, 7c and 7d pointing above the silicon substrates 2a, 2b and 2c can be separated from the bath liquid 14 by a suction nozzle. is there.

  In a second embodiment not shown, an electronic switch 8 is used to selectively couple the corresponding contact roller 7 with both poles of the electroplating current source 6. As long as the corresponding contact roller 7 is in contact with the contact surface of the silicon substrate 2, the coupling with the positive electrode of the electroplating current source 6 takes place in the conventional manner, in which case the desired electroplating strengthening is performed instead. Done. On the other hand, the contact roller 7 is coupled to the negative pole of the electroplating current source 6 between the contact surfaces of the continuous silicon substrate 2. In this way, metal deposits present on the contact roller 7 can be redissolved in the solution, thereby further extending the service life of the contact roller 7. However, it is natural that this measure is only possible in the case of reinforced metals that are brought into solution by electrolysis and that are deposited during the use of gold.

It is a schematic side view of an apparatus for strengthening a metal conductor row deposited on a silicon substrate by electroplating. FIG. 2 is an enlarged view of details of FIG. 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Processing apparatus 2 Silicon substrate 3 Drive roller 4 Transfer direction 5 Anode 6 Electroplating current source 7 Contact roller (contact apparatus)
8 Electronic switch 9 Machine control unit 10 Sensor (positioning device)
11 Spraying device (suction device)
12 Gas supply direction 13 Gas supply direction 14 Electroplating bath liquid 15 Bath liquid surface

Claims (10)

A method for processing flat fragile substrates, particularly for the semiconductor and solar energy industries, comprising:
The substrate is guided through the bath liquid in a horizontal passage, and at least one contact surface of the substrate is in contact with a contact device in the horizontal passage to be distinguished from a potential of a counter electrode disposed in the bath liquid. In the method of making a potential,
The contact area between the contact device (7) and the contact surface of the substrate (2) is freely sprayed or sucked by a processing liquid (14),
Processing method.   The processing method according to claim 1, wherein air is used as the gas for free spraying.   The processing method according to claim 1, wherein nitrogen is used as the gas for free spraying.   The potential required to process the substrate (2) only during the time when the path of movement of the substrate (2) is tracked and the contact device (7) is in contact with the contact surface of the substrate (2). The processing method according to any one of claims 1 to 3, characterized in that is applied to the at least one contact device (7).   A second potential that is suitable for reversing the reaction that proceeds during the treatment with the first potential during a time when the contact device (7) is not in contact with the contact surface of the substrate (2), The processing method according to claim 4, characterized in that it is applied to the at least one contact device (7). An apparatus for processing flat fragile substrates, particularly for the semiconductor and solar energy industries,
a) a bath container filled with the treatment liquid up to the specified liquid level;
b) a transport device capable of guiding the substrate through the bath liquid in a horizontal passage;
c) a processing power supply;
d) at least one contact device that can be brought into contact with at least one contact surface attached to the substrate and then couples the contact surface with one pole of the processing power source;
e) having at least one counter electrode disposed in the processing liquid and coupled to the other pole of the processing power source,
f) at least one contact device (7) equipped to allow free spraying or suction of a contact area between the contact device (7) and the contact surface of the substrate (2); A spraying or suction device (11) is provided,
Processing equipment.   The processing apparatus according to claim 6, wherein the gas is air used for free spraying.   The processing apparatus according to claim 6, wherein the gas is nitrogen used for free spraying. a) a positioning device (10) capable of detecting the position of each substrate (2) is provided;
b) The potential required to process the substrate (2) only during the time that the contact device (7) is in contact with the contact surface of the substrate (2) according to the output signal of the positioning device (10). 9. A processing device according to any one of claims 6 to 8, characterized in that a control unit (9) is provided for applying a pressure to the at least one contact device (7).   During the time when the contact device (7) is not in contact with the contact surface of the substrate (2), the controller is suitable for reversing the reaction that proceeds during the treatment with the first potential. 10. Processing device according to claim 9, characterized in that a potential of 2 is applied to the at least one contact device (7).

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