WO2008071239A1 - Appareil et procédé de traitement chimique et électrolytique humide d'un seul côté - Google Patents

Appareil et procédé de traitement chimique et électrolytique humide d'un seul côté Download PDF

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Publication number
WO2008071239A1
WO2008071239A1 PCT/EP2007/003746 EP2007003746W WO2008071239A1 WO 2008071239 A1 WO2008071239 A1 WO 2008071239A1 EP 2007003746 W EP2007003746 W EP 2007003746W WO 2008071239 A1 WO2008071239 A1 WO 2008071239A1
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WO
WIPO (PCT)
Prior art keywords
good
treatment
contact
electrolyte
treatment chamber
Prior art date
Application number
PCT/EP2007/003746
Other languages
English (en)
Inventor
Norbert BÜRGER
Dietmar LÜTKE NOTARP
Konrad Kaltenbach
Franck Delahaye
Original Assignee
Rena Sondermaschinen Gmbh
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Filing date
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Application filed by Rena Sondermaschinen Gmbh filed Critical Rena Sondermaschinen Gmbh
Publication of WO2008071239A1 publication Critical patent/WO2008071239A1/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
    • C25D5/08—Electroplating with moving electrolyte e.g. jet electroplating
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D17/00—Constructional parts, or assemblies thereof, of cells for electrolytic coating
    • C25D17/001—Apparatus specially adapted for electrolytic coating of wafers, e.g. semiconductors or solar cells
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D17/00—Constructional parts, or assemblies thereof, of cells for electrolytic coating
    • C25D17/02—Tanks; Installations therefor
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D17/00—Constructional parts, or assemblies thereof, of cells for electrolytic coating
    • C25D17/06—Suspending or supporting devices for articles to be coated
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D7/00—Electroplating characterised by the article coated
    • C25D7/12—Semiconductors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/02—Details
    • H01L31/0224—Electrodes
    • H01L31/022408—Electrodes for devices characterised by at least one potential jump barrier or surface barrier
    • H01L31/022425—Electrodes for devices characterised by at least one potential jump barrier or surface barrier for solar cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy

Definitions

  • the invention relates to the wet chemical, electrochemical and electrolytic treatment as well as the cleaning of planar goods, in particular of substrates such as wafers, solar cells, hybrids, CD's or the like.
  • Typical examples for treatment methods subsequent to surface cleaning relate to the activating, doping, electrochemical / electrolytic or chemical metallizing or etching, stripping, and the like, of suitable substrates.
  • Such goods are only treated single-sided at the surface. Thereby, a full surface as well as a structured treatment can occur.
  • the backside that is not to be treated usually has to be securely protected against wetting caused by the treatment fluid.
  • cup- or fountain-treatment devices are known.
  • the good to be treated itself closes on one side the treatment chamber of such devices. During the entire treatment, the good is connected to the treatment chamber e.g. by means of a substrate holder, a gripper, or a clamping fixture.
  • the treatment fluid can stream against the treated surface so that a chemical modification of the good can be effected.
  • Sealing elements that are located at the clamping devices close to the good avoid wetting of the backside that must not be treated.
  • Such sealing elements can also be formed by appropriate grippers, vacuum chucks or other transportation devices that cover the full area of the good' s backside during contact, thus protecting it from undesired wetting.
  • said devices can be, for example, of the mechanical, the Bernoulli, or the vacuum type.
  • a typical example of an apparatus for the treatment of the afore-mentioned goods is disclosed in document WO 99/16963 and relates to electrolytic metallization of wafers.
  • Inside the treatment chamber an anode, and, if necessary, a scattering orifice are integrated.
  • the good's surface that is to be treated forms the cathode of the electrolytic cell.
  • the electrolyte streams from below into the treatment chamber and then leaves the same via overflowing over its edge.
  • the good is held and contacted by means of a carrier consisting of sample holders, rotors, stators, power transmission and measurement devices.
  • the thus clamped good is horizontally and vertically positioned and fixed by means of a transporting device at the surface of the overflowing treatment fluid.
  • the immersion depth of the good is adjusted so that only the bottom side that is to be treated is wetted and stays in contact with the treatment fluid.
  • the electrically conductive sample holders that are located at the bottom side of the good are being metallized as well.
  • These undesirably metallized holders must be de-metallized from time to time.
  • the carrier is positioned without the good during an additional process step over the treatment chamber in a way such that the metallized parts of the sample holder are immersed in the treatment fluid.
  • the sample holders are switched anodically against a cathodic auxiliary electrode.
  • the sample holders are then electrolytically de-metallized by means of a current source.
  • the auxiliary electrode absorbs the metal, e.g. the copper. It must be exchanged after several etching processes.
  • the good must be clamped to a carrier for treatment and be held by it during the entire processing. Therefore, the height level of the good with respect to the treatment fluid has to be determined individually and applied by precisely adjusting a vertical drive mechanism. Since the usually very thin good, having a thickness of e.g. 0.3 mm, practically hovers above the treatment chamber, a very solid mechanical construction must be provided for the setup of the treatment chamber as well as for the transportation device and the carrier. In the future, the thickness of solar cells made from silicon will be reduced to approximately 0.1 mm. Furthermore, temperature changes during treatment may affect the height level of the the carrier with respect to the treatment fluid.
  • US 5,000,827 discloses an electrolytic cell for partial metallization of wafers.
  • the electrolyte that streams in from the bottom leaves the cell by means of an overflow edge.
  • the distance H is adjusted by means of support elements in the form of screws.
  • the distance S is determind by the diameter of the wafer and the electrolytic cell and that has to be adjusted once.
  • Electrical contacting takes place at the dry upper side of the wafer, whereby the good stays in touch with this contacting means during the electrolytic treatment. Since the electrolyte does not reach the electrical contacts, these are not metallized. However, both sides of the good have to be electrically connected to each other. In this case, a de- metallization of the contacts is not necessary.
  • the support elements that also fix the wafer against lateral movement over the cell are essential parts of that invention.
  • laterally acting limiters or end stops do in practice cause the treatment fluid to be pulled up at or along the edge of the good due to capillary forces.
  • the fluid undesirably contacts the upper side of the good in the vicinity of these limiters, often resulting in reject loss. Therefore, such limiters cannot be used in cases, where an unprotected upper side is even not allowed to be wetted partially.
  • electroplating devices for wafers are e.g. disclosed in DE 600 25 773 T2 (Fig. 1) and US 6,001,235 (Fig. 1).
  • the electrical contacts for connection to the bath current source rise vertically above the electrolyte. Up to the electrolyte/air boundary, also the contacts are metallized during metallization of the good, at least up to a possible partially isolating cover layer. Since in practice, this isolating cover layer is subject to wear, it is usually omitted, also because the electrical isolation does not or only insufficiently adhere to the base material which usually consists of an electrochemically inert metal such as titanium or niobium.
  • the unavoidable oxide formation at the surface of these metals is the reason for the insufficient adhesion of such an isolating cover layer to the contacts.
  • the metallization of the metallic blank contact regions must thus repeatedly be removed during ongoing production.
  • the contacts in the treatment chamber are switched anodically against a cathodic auxiliary electrode.
  • this electrolytic de-metallization it is observed that in the vicinity of the electrolyte/air boundary only an incomplete removal of the metallized layer takes place.
  • more and more metal builds up on the contact in this border region more or less annularly. Additionally, crystals of the electrolyte used can be deposited in this region. Automatic de-metallization and cleaning of the contacts therefore is insufficient for an uninterrupted production. Every now and then, manual interventions for the removal of the interfering annular deposits are necessary.
  • the object of the present invention is to provide an apparatus and methods which overcome the above drawbacks of the prior art and ensure the single-side wet chemical, electrochemical and/or electrolytic treatment or cleaning of a completely flat or structured bottom side of a planar good that is placed on at least one support over the treatment chamber in a manner such that almost no horizontal force which might dislocate the good acts on the same.
  • the present invention enables the practitioner to exclusively treat only one side of a planar good without holding and/or laterally limiting the same and without protecting the good's other side against being wetted. Accordingly, the apparatus according to claim 1 and the method according to claim 20 are provided. Preferred embodiments are subject matter of respective independent claims. According to the invention, mechanical stresses or other forces acting on the good are avoided in order to significantly reduce the danger of breakage for fragile good.
  • the present invention enables to completely de-metallize and clean the electrically non-insulated contacts that are fixed and permanently arranged with respect to the treatment chamber.
  • the good remained positioned on the supports not comprising any lateral end stops and being located at the upper part of the tank wall of the treatment chamber, if the gap height, due to the precise positioning of the at least one support in relation to the overflow edge, was substantially exactly the same over the entire circumference of the treatment chamber, and if the overflow edge and the gap ran exactly horizontal along the entire circumference. This was achieved when the supporting points of the supports for the good were levelled equal to the surface of the treatment fluid. For this purpose, it proved to be helpful if the height level of the supports could be adjusted within a sufficient range. Since more than one support was used in this experiment, it also proved to be helpful if the supports were aligned at least almost symmetrically to the vertical center line of the treatment chamber.
  • the present invention can also be carried out by using an apparatus with only one support, which can be one lateral or central support, or a continuous or interrupted circumferential, ring-shaped support.
  • the technical feature of said at least one support is exemplified in an apparatus having three separate and symmetrically distributed supports.
  • the horizontal components of the force of adhesion between the good and the treatment fluid almost neutralize each other. This is particularly true, if the supports are symmetrically arranged and if the stream of the treatment fluid contacting the good' s bottom side is directed radial-symmetrically .
  • the good once placed onto supports without any lateral end stops remained in position without any frame, gripper, holder, or support with lateral limiters being necessary to achieve this result.
  • no wetting of the good's upper side can take place.
  • the upper side does not need to be protected in any kind, e.g. by covering it with a protection layer or by means of a mechanical cover or a gripper such as a commonly used vacuum chuck. In addition, no detrimental mechanical force or stress acts on the good.
  • the amount of treatment fluid streaming into the treatment chamber is adjusted by means of a pump and/or valves, such that the upper side of the good while being placed on the surface of the treatment fluid that streams out of the treatment chamber and exactly positioned by means of the at least one support is not wetted.
  • the surface tension of the fluid is sufficient to even prevent the thin edge of the good from being wetted.
  • the vertical components of adhesion between good and treatment fluid at the border of the good cause the good to be gently adhered to the at least one support.
  • the at least one support is electrically conductive and can, advantageously, also serve as electrical contact in order to apply the current necessary for the electrolytic treatment of the good.
  • the electrical contacting of the good can be achieved using one or more separate contacts that can connect to the bottom and/or the upper side of the good.
  • the embodiment of one or more integrated mechanical and electrical contacts is preferred.
  • a very reliable electrical contacting is achieved by the vertically acting adhesion forces. Due to the vertical force components, an albeit small frictional force acts between the support areas of the supports and the bottom side of the good that is placed onto them. This further stabilizes the horizontal and centered position of the good at the supports, so that, even with no lateral end stops or limiters, the good surprisingly remains at the central position where it has been placed before.
  • the at least one electrical contact for the power supply to the bottom side of the good is electrolytically de-metallized after one or several metallization procedures within the same electrolyte.
  • the apparatus additionally comprises means that serve to move the electrolyte/air boundary at the contact and/or the surface of the electrolyte for metallization and de-metallization in relation to the natural electrolyte/air boundary.
  • the flow rate of the electrolyte can be nearly or exactly the same for both cases .
  • two preferred embodiments exist that are subsequently referred to as case 1 and case 2 and comprise said means in the form of at least one gas distributor.
  • the electrolyte and thus, the electrolyte/air boundary in the vicinity of each contact is moved towards the treatment chamber by a gas stream, preferably an air stream, during metallization of the treatment good.
  • a gas stream preferably an air stream
  • this can be achieved by a gas stream that is directed close to each contact against the surface level of the electrolyte inside the treatment chamber.
  • the flow direction of the gas is pointed towards the approximate center of the treatment chamber.
  • the gas stream is directed distant to the contacts against the level of the electrolyte in the treatment chamber in such a way, that the level rises at each contact and wets a region represented by the original natural electrolyte/air boundary at each contact.
  • a total electrolytic de-metallization takes place, since the contact's area that has to be de-metallized is entirely positioned within the electrolyte.
  • the electrolytic de-metallization of the contact (s) can be carried out with a significantly higher current density than it is applicable for the metallization of the treatment good.
  • de-metallization can be effected in a short period of time, e.g. in 20 seconds, as compared to a typical metallization time of 10 to 30 minutes or longer.
  • the electrolyte/air boundary during de-metallization of the at least one contact is sufficiently moved by any of the following steps which can be performed alone or in combination, such that the boundary that is formed during previous metallization is entirely positioned within the electrolyte at least in the vicinity of the at least one contact: a) directing a gas stream in-line with the flow direction of the electrolyte at the contact or against the surface of the electrolyte; b) lowering the at least one contact for de-metallization into the treatment fluid, e.g. by providing a temporary mechanical tiltability for each contact; c) locally applying treatment fluid onto the at least one contact; d) elevating the level of the treatment fluid by elevation of the overflow edge, e.g. by using mechanical blinds or the like; and/or e) elevating the level of the treatment fluid by increasing its flow.
  • the complete de-metallization and cleaning of each contact during each de-metallization allows for an uninterrupted automatic treatment of good in an electroplating device.
  • its surface can be covered with an electrically conductive diamond layer and/or partially covered with an electrically insulating layer.
  • the surface of the bottom side of the good to be treated electrolytically must comprise at least one contact area for its electrical contacting using the at least one contact, wherein the contact area is electrically connected to the surface to be treated. If the good is to be contacted at its bottom side, this contact area must fit to the design of the at least one contact so that the current may appropriately be applied to the good. Alternatively, the good can, in certain cases, be contacted via the dry upper side, as long as the bottom side is electrically connected with said upper side. This can e.g. be achieved by the provision of at least one electrical contact located outside the electrolyte, wherein the electroplating current from the bath current source is fed to the good via the surrounding edge of the good and/or through the good itself.
  • this electrical connection can be provided by illuminating the n-doped bottom side.
  • the solar cell then acts as a direct current source that is connected in series with the (bath) current source that is equally poled during electroplating.
  • An appropriately illuminated solar cell is capable of carrying the necessary electroplating currents of 1 A and more.
  • An advantage of this embodiment is the lack of metallization of the dry contact means.
  • the required illuminants including reflectors can be located inside the electrolyte in the work tank and also outside of the work tank. The outside arrangement requires at least partially transparent tank walls of the treatment chamber. All known light sources, in particular halogen lamps and light emitting diodes, are suitable as illuminants.
  • the apparatus thus comprises at least one light source for the activation of light sensitive components of the treatment fluid and/or for effecting chemical, electrochemical or electrolytic processing. It is preferably located inside the treatment chamber, but can also be located outside.
  • This at least one light source can be of any type, including halogen lamps, light emitting diodes, fluorescence lamps, ultraviolet or infrared light sources, lasers, or combinations of the same.
  • the apparatus further comprises at least one transporting means for conveying the good to and from the treatment chamber, with means for positioning and placing the good onto the at least one support over the treatment chamber and for its repositioning and picking up after the treatment.
  • transporting means for conveying the good to and from the treatment chamber, with means for positioning and placing the good onto the at least one support over the treatment chamber and for its repositioning and picking up after the treatment.
  • These latter means suitable for loading and unloading are preferably designed to exclusively contact the bottom side of the good. With other words, means that contact the edge and/or the upper side of the good should be avoided.
  • a suitable means comprises one or more rod-shaped elements that are bent and/or sharply- angled to reach the bottom side of a good being placed on the surface of the treatment fluid without contacting its edge.
  • Figure 1 shows the basic arrangement for the exclusive single side wet chemical treatment of a good as a cross sectional view and a top view.
  • Figure 2 shows the basic arrangement for the single side electrochemical and/or electrolytic treatment of a good with details of the contact region.
  • Figure 3 shows different embodiments of the supports for the good and details in the support region.
  • Figure 4a shows embodiments of the overflow edge of the treatment chamber in a side view.
  • Figure 4b shows embodiments of the overflow edge of the treatment chamber in a cross sectional view.
  • Figure 5 shows an arrangement of a plurality of treatment chambers for electrochemical and/or electrolytic metallization of goods within a production facility.
  • Figure 6 shows the arrangement of Fig. 5 during electrolytic de-metallization of the contacts that, in this case, also serve as supports during the treatment of the good.
  • Figure 7a shows in a detail a stretched contact during metallization of the treatment good according to case 1.
  • Figure 7b shows the situation during the de-metallization of the stretched contact.
  • Figure 8a shows in a detail an angled contact during metallization of the treatment good according to case 1.
  • Figure 8b shows the situation during the de-metallization of the angled contact .
  • Figure 9a shows in a detail an angled contact during metallization of the treatment good according to case 2.
  • Figure 9b shows the situation during the de-metallization of the angled contact.
  • Figure 10 shows an arrangement for the electrolytic metallization of silicon solar cells with an illuminated bottom side.
  • the planar good 1 is placed onto the contacts or supports 2 above a treatment chamber 3.
  • the at least three supports 2 for a circular shaped good 1 or the at least four supports 2 for an angular good 1 are positioned at the border of the treatment chamber 3 and arranged symmetrically to its vertical center line 9.
  • the gravitational contact forces between the good 1 and the here rod-shaped supports 2 are almost identical, which is particularly important for the current transmission during an electrochemical and/or electrolytic treatment.
  • the treatment chamber 3 has an inner cross section that is substantially congruent with the shape and the dimensions of the good 1 that is to be treated. Differing from this congruence, the good can preferably be slightly larger than the inner cross section of the treatment chamber 3.
  • the good 1 can also be slightly smaller than the treatment chamber 3.
  • the inner cross section can be circular, quadratic, or rectangular, with or without shortened corners or curves, e.g. for solar cells, or it can be differently shaped.
  • the overhangs should be chosen to be at least nearly symmetrical with the vertical center line 9, so that horizontally resulting forces acting on the good 1 are reduced or avoided.
  • a non- congruence of the cross section of the treatment chamber 3 and the good 1 can be chosen, in order to selectively electroplate only the region of the good that is contacted with the treatment fluid 24.
  • the inner shape of the latter can be adapted using inserts or the like that reduce the inner diameter and/or shape of the treatment chamber 3 accordingly.
  • the treatment fluid exemplarily streams centrally into the treatment chamber 3. This is symbolically represented by the flow direction arrows 4.
  • a pump 5 circularly delivers the treatment fluid through an inlet opening 6 in the form of a pipe into the treatment chamber 3 in direction towards the bottom side 7 of the good 1 to be treated.
  • any means for delivering the treatment fluid into the treatment chamber can be used, including passive means such as elevated fluid containers .
  • the treatment fluid is directed at the bottom side 7 radially outwards to the border 10 of the good 1. Inside the treatment chamber that is filled with treatment fluid, but at least in the vicinity of the good, the stream is directed radial-symmetrically from the vertical center line 9 towards all sides of the treatment chamber 3.
  • rotational-symmetric (symmetrizing) means 11 such as baffles, scatter orifices
  • annularly or centrally feeding in of the treatment fluid into the bottom of the treatment chamber 3 and/or by using multiple symmetrical means for feeding in of the treatment fluid into the bottom part of the treatment chamber 3.
  • This fluid causes adhesion forces which pull the good floating on the fluid surface outwards. Since the stream, however, flows radial-symmetri- cally, these forces neutralize each other, at least up to an insignificant small remainder that is due to tolerance.
  • a horizontal gap is formed between the overflow edge 13 and the good 1 placed onto the supports 2 and allows the treatment fluid to stream out all-around of the treatment chamber 3 and into a reservoir 14, wherein the height of fall is adjusted to be small in order to avoid an undesired drag-in of air.
  • the total volume of the treatment fluid is chosen to be so large that its level inside the reservoir 14 almost reaches the overflow edge 13.
  • a pump 5 delivers the treatment fluid from the reservoir 14 back into the treatment chamber 3.
  • a drive with variable rotational speed for the pump, or adjustable chokes, valves and the like can be used inside the pipes.
  • a streaming fluid volume between 3 and 20 liters per minute for each treatment chamber was chosen in the experiments.
  • the respective amount is primarily process related.
  • the fixation of the good 1 above the treatment chamber 3 without lateral end stops allows flow volume to be adjusted within the above wide range, without a dislocation of the good taking place.
  • a top view shows a typical solar cell with shortened edges .
  • the inner cross section of the treatment chamber 3 is of the same shape.
  • the overflow edge 13 is hidden by the good 1 in this drawing and therefore indicated by broken lines. No lateral end stops are used in this apparatus.
  • further rotational- symmetric means 11 that preferably are axially-symmetric to the vertical center line 9, such as baffles, membranes, diaphragms, soluble or insoluble anodes and other electrodes or equipment, may be integrated inside the treatment chamber 3. They are designed to maintain the uniform symmetrical flow along the good.
  • soluble anodes self-supporting plates with or without holes as well as bulk material can be used.
  • the bulk material e.g. metal spheres, lay on an electrically conductive and chemically inert metal grate that also serves for electrical connection to a bath current source.
  • the bulk material is covered on top by an ion-permeable fabric filter, e.g. of polypropylene.
  • the treatment fluid streams towards the bottom side 7 of the good while passing this arrangement that altogether is referred to as anode or, within this description, generally as rotational-symmetric means 11.
  • the supports 2 determine the gap height 15 as shown in figure 3. Therefore, they must be positioned mechanically precise close to the treatment chamber.
  • the at least one support can be made from an electrically non-conducting material, or from metal in case of an electrochemical and/or electrolytic treatment of the good 1. In this case, said at least one support preferably also serves as electrical contact 2 for the power supply to the good 1.
  • the support (s) 2 can be fixed to the tank wall 17, as depicted in figure 1, or to separate support mounts 16, as depicted in figure 2.
  • Figure 2 illustrates the electrochemical and/or electrolytic treatment of the good 1.
  • a soluble or insoluble anode 21 is arranged inside the treatment chamber 3.
  • the good 1 is cathodically switched by a bath current source 22 against the anode 21.
  • the wetted bottom side 7 of the good 1 and the wetted regions of the metallic blank contacts 2 are electroplated by the electrolyte up to the electrolyte/air boundary 25.
  • crystals can deposit at this boundary as well.
  • the contact metallization 30 as well as the crystal formation are disadvantageous for the continuous operation of an electroplating device. After each or several metallization procedures, the contacts 2 must be electrolytically de- metallized and cleaned.
  • a multiple extension of the de-metallization time probably could electrolytically dissolve the metal ring 31 to a large extent. However, this is associated with a loss of the system's production capacity and thus should be avoided.
  • Another possibility of electrolytically dissolving or etching the metal ring 31 could be the increase of the circulated electrolyte flow volume during de-metallization. However, this would necessitate a more complex arrangement and cause the disadvantage of an increased drag-in of air into the electrolyte due to a pushed and therefore more disturbed flow.
  • the air affects the additives of the electrolyte, resulting in a disadvantageous rise of its consumption.
  • the de-metallization time preferably is very short compared to the plating time, the temporary flow increase has only a minor influence on the electrolyte system.
  • the supports 2 are depicted in figure 3. In order to avoid the wetting of edge 23 of the good, a contact between support 2 and good 1 within this critical region should be avoided. This is achieved by the depicted shapes and orientations of the supports 2 as well as by the overhang of the good with respect to the tank rim. In order to avoid wetting of the support mounts 16 by the treatment fluid the supports can be designed siphon-shaped, as depicted.
  • Figure 4a shows embodiments of the overflow edge 13 in a side view.
  • a straight edge line is preferably used.
  • Differently shaped incisions 18 can be located in parts of or on the entire overflow edge 13, as depicted in this figure.
  • a sinusoidal shape can be chosen.
  • These incisions serve for the individual influence (reduction) of the treatment fluid' s flow speed at the border region of the treatment chamber.
  • Depth and spacing of the incisions 18 are in the range of 0.5 mm to 5 mm.
  • the gap height 15 can vary between 0.3 mm and 6 mm, and preferably ranges between 1 mm and 3 mm. The gap height 15 is measured from the uppermost part of the incisions 18.
  • Figure 4b shows in cross section different embodiments of the tank wall 17 in the region of the overflow edge 13.
  • the shape of the cross section depends on the process.
  • the rounded overflow edge reduces a vortex formation in this region.
  • the edge width 19 of the overflow edge can range from a sharp corner (more than 0.0 mm) to 5 mm and preferably is between 0.5 mm and 2.5 mm.
  • Figure 5 shows a plurality of treatment chambers 3, as they are arranged side by side or one after another in a larger production device.
  • the reservoir 14 takes up the overflowing treatment fluid from one, several or all treatment chambers 3.
  • a common pump 5 delivers the treatment fluid to a distribution pipe 20 that is in connection with the treatment chambers 3 via central inlet pipes 6.
  • the distribution pipe 20 can incorporate an inner pipe having an equal length and being equipped with openings, into which the treatment fluid is first delivered by the pump. From there, the fluid then reaches the distribution pipe 20.
  • each treatment chamber 3 comprises a soluble or insoluble anode 21 that is preferably equipped with openings that allow the electrolyte that is needed for the electrochemical or electrolytic treatment of the good 1 to pass through.
  • the good 1 is cathodically switched by a bath current source 22.
  • a unipolar or bipolar pulsed current source is suitable as well.
  • a bath current source 22 can supply several treatment chambers 3 with bath current for electroplating.
  • the treatment chambers 3 are preferably loaded and unloaded with goods in parallel, i.e. simultaneously, by transportation means not shown here. As a result of this, the entire production device requires less transportation means.
  • the situation of de-metallizing the contacts 2 after one or several metallization processes is shown in figure 6.
  • a good 1 is not loaded.
  • the contacts 2 that are located in the region of the overflow of the electrolyte are anodically switched by means of the bath current source 22 and switching means not depicted here.
  • the anode 21 serves as a cathode, onto which the metal that is removed from the contacts 2, e.g. copper, tin or silver, is deposited. In this manner, this metal can be usefully reused in the following electroplating step.
  • FIG. 5 and 6 the equipment for the flow of the gas stream against the contacts 2 is not shown due to simplification of the figure.
  • These devices for the complete removal of the entire contact metallization 30 that takes place during each metallizing process, and for the avoidance of the build-up of metal rings 31, are shown in the following figures 7 to 9.
  • Figure 7a illustrates the situation during metallization of the good 1.
  • the contact 2 having e.g. a circular or rectangular shape, contacts and supports the good. In case of a circular shape, the good rests on at least three contacts 2 over the treatment chamber 3.
  • the treatment chamber can comprise only one support that is substantially ring-shaped and located close to the inner tank wall (not shown) .
  • the electrolyte 24 that is delivered by a pump (not shown) streams along the bottom side 7 of the good 1, and from there over the overflow edge 13 in an only partially visible reservoir 14. Due to the electrolyte 24 that streams out of the treatment chamber 3, a natural electrolyte/air boundary 25 develops more or less diffusely in the border region of the good 1 and therefore close to the overflow edge 13.
  • This boundary and thus also the region of the contact that is metallized during each metallization step up to the electrolyte/air boundary 25 is, during electroplating, displaced in direction to the center of the treatment chamber 3 by means of at least one gas stream 26 that preferably is an air stream.
  • the air stream 26 emanates from at least one individual opening or nozzle 27, that is arranged at gas distributors 28, preferably at gas distribution pipes.
  • the gas distributors 28 are fed e.g. with compressed air by at least one compactor or compressor (not shown) .
  • the air stream 26 can be controlled and therefore switched on, choked, and turned off by means of a valve 29, a flap or the like.
  • the emanating gas or air, respectively can be controlled collectively in groups. This purpose is served by the flaps or valves 29 that are located between the compressor and the nozzles 27.
  • Amount and velocity of each emanating air stream are adjusted in a manner such that the electrolytic de-metallization that follows metallization without gas stream 26 results in a complete de-metallization and cleaning of the contacts within the shortest possible time.
  • the electrolyte/air boundary 25 during metallization is sufficiently moved back towards the center of the treatment chamber 3, such that, during subsequent de-metallization with the gas stream being choked of shut off, the electrolyte/air boundary formed during metallization is entirely positioned within the electrolyte.
  • the electrolyte/air boundary 25 is shifted in direction to the contact. This natural boundary is then located in the region of the contact 2 that was not metallized or contaminated during metallization, because it stayed dry due to the air stream 26. Therefore, a complete de-metallization of each contact is achieved in each de-metallization process.
  • the gas stream is directed against the surface of the electrolyte during metallization, so that the level of the electrolyte inside the treatment chamber 3 is lowered at least in the vicinity of the contacts, also resulting in a displacement of the electrolyte/air boundary 25.
  • Figure 7b illustrates the situation at the beginning of the de-metallization of the contact metallization 30 with the air stream being shut off.
  • the electrolyte/air boundary 25 that develops naturally has been shifted outwards .
  • the contact metallization 30 is completely positioned within the electrolyte enabling its complete electrolytic dissolution. Eventually formed crystals are also dissolved by the electrolyte stream. Even after many metallization and de- metallization processes, a metal ring 31 cannot develop at the at least one contact .
  • Figures 8a and 8b relate to case 1 and show details of a similar electroplating device with both process situations (metallization in figure 8a; de-metallization in figure 8b) .
  • the contact mount 16 is arranged above the highest level of the electrolyte 24.
  • the electrolyte cannot spread itself up to the contact mount 16 when the air is shut off.
  • Figure 9a relates to case 2 and shows an angled contact 2 during electrolytic metallization.
  • the electrolyte streams over the overflow edge 13 of the treatment chamber 3 into the reservoir 14. This gives rise to the development of the natural electrolyte/air boundary 25 at the depicted region of the angled contact 2.
  • this boundary has to be entirely positioned within the electrolyte during de-metallization. This preferably takes place by means of at least one gas stream 26 directed in-line with the streaming electrolyte, as e.g. exemplified in figure 9b.
  • a gas stream 26 emanates from at least one nozzle 27 and causes the electrolyte or the electrolyte stream, at least in the vicinity of the contacts 2, to be displaced in a manner such that the newly developing electrolyte/air boundary 25, in relation to the original natural electrolyte/air boundary, is moved against gravity, i.e. outwards. This region of the contacts was not reached by the electrolyte during metallization and therefore not metallized.
  • the at least one gas stream is directed against the surface of the electrolyte such that the level of the electrolyte within the treatment chamber 3 rises at least in the vicinity of each contact, thereby elevating the electrolyte/air boundary 25.
  • the gas stream is also directed almost horizontal in direction of the contact mount 16, as depicted in figure 9b. Due to the different electrolyte/air boundaries 25 upon metallization and de- metallization, a complete de-metallization and cleaning of the contacts 2 is achieved in each de-metallization process.
  • De-metallization usually takes place against a counter electrode that is used as an auxiliary electrode.
  • the counter electrode (not shown) can also be the soluble or insoluble anode that is located within the treatment chamber 3.
  • the anode is cathodically switched against the contacts 2 that are to be de-metallized.
  • the metal that has been dissolved from the contacts 2 and deposited onto the anode can usefully be recycled.
  • it is re- dissolved from there and used for metallization of the good 1.
  • FIG 10 shows another treatment chamber with an electrolytic cell 37.
  • the good 1 is a solar cell with p- and n-doped areas that is illuminated.
  • only the bottom side 7 that is to be treated is in contact with the electrolyte 24 of the treatment chamber 3.
  • the electrically conducting upper side 38 of the solar cell shall not be metallized.
  • the electrical contacting can be realized using the dry upper side 38, if the electroplated bottom side 7 is illuminated. In this case, the otherwise necessary de-metallization of the contact means is omitted.
  • the illuminated solar cell electrically acts as a direct current source 35 that is drawn as an equivalent circuit diagram.
  • This direct current source 35 generates the solar cell voltage U s , an EMF (electromotive force) that approximately amounts to 0.6 V, dependent of the illuminance.
  • EMF electrotive force
  • Current-carrying, this direct current source 35 is connected to the electroplating circuit, that consists of the bath current source 22, the electrical upper side contacts 36, the direct current source 35, the bottom side 7 that is to be treated, the electrolyte 24 within the electrolytic cell 37, and a soluble or insoluble anode 21.
  • the polarities of the voltages involved in this electroplating circuit are denoted in figure 10.
  • the terminal voltage U B of the bath current source 22 is the terminal voltage U B of the bath current source 22, the solar cell voltage U s as an electromotive force EMF, and the cell voltage U 2 of the electrolytic cell as the voltage at the load or the consumer, respectively. Due to the serial connection of the two driving voltages, the terminal voltage U B of the bath current source 22 is smaller than the cell voltage U z , because it is reduced to nearly the amount of the EMF.
  • the bottom side 7 of the good 1 is illuminated by a light source 34. Suitable light sources offer a light spectrum that is close to sunlight. If desired, the light can be amplified and/or directed onto the good 1 by a reflector 33. Due to the illumination, the solar cell generates an EMF of approximately 0.6 V with a low internal resistance. This resistor of a silicon solar cell with a surface of 1 to 2 dm 2 is capable of securely conducting an electroplating current in the order of magnitude of 1 Ampere and more.
  • the light source 34 can also be located outside of an at least partially
  • the electrolyte can be fed symmetrically into the treatment chamber 3 by means of e.g. a distributor ring 32. This avoids dimming of the light radiating from the light source.
  • the invention is particularly suitable for all typical electrolytic devices and for all planar goods such as wafers, solar cells, circuit boards, and hybrids. Furthermore, all metals that are suitable for electrolytic depositing and dissolving can be used, e.g. such as copper, nickel, tin, and silver.
  • the apparatus according to the invention is also suitable for electrolytic etching with a reversed polarization of the bath current source. For this purpose, a counter electrode is arranged within the treatment chamber 3 and takes up the etched metal. This electrode is exchanged after a prolonged operating period.

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Abstract

L'invention porte sur le traitement chimique ou électrolytique humide d'un objet plan, c'est-à-dire d'une tranche de silicium, qui dans l'état de la technique se traite à l'aide de cadres ou de préhenseurs techniquement complexes et à l'intérieur de chambres de traitement. Pour des objets fragiles, par exemple des cellules solaires de silicium, le traitement est particulièrement long, notamment si le fond de l'objet ne doit pas être mouillé. Selon l'invention, on place l'objet 1 sur une chambre de traitement 3 disposée verticalement, sans cadre, préhenseur ou support de manière à ce que seul son fond soit mouillé. Du fait de la rotation de courants symétriques 4 appliqués sur le fond 7 de l'objet placé sur au moins un support 2, les forces d'adhérence agissant horizontalement sur l'objet 1 se neutralisent, et le déplacement latéral des objets ne se produit pas. On peut donc se passer des limiteurs généralement utilisés ou les butés d'extrémités latérales. Selon l'invention, les composantes agissant verticalement de la force d'adhérence font que l'objet 1 adhère aux supports ou aux contacts 2 et produit un contact électrique sûr pour le traitement électrolytique. Pour obtenir une métallisation complète des contacts 2 la limite naturelle électrolyte/air 25 est déplacée vers les contacts au moyen d'un courant gazeux 26 dirigé contre la direction du flux ou contre le niveau de l'électrolyte. Pour les cellules solaires, la métallisation des contacts peut être complètement évitée par l'éclairage du fond qui doit être galvanisé, puisque les contacts sont placés à l'extérieur de l'électrolyte.
PCT/EP2007/003746 2006-12-13 2007-04-27 Appareil et procédé de traitement chimique et électrolytique humide d'un seul côté WO2008071239A1 (fr)

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Cited By (7)

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Publication number Priority date Publication date Assignee Title
WO2009152896A1 (fr) * 2008-06-19 2009-12-23 Rena Gmbh Dispositif et procédé pour le traitement unilatéral par voie chimique humide et/ou électrolytique d'une matière
US20100108525A1 (en) * 2008-11-06 2010-05-06 Andreas Krause Light-induced plating
DE102009049565A1 (de) * 2009-10-09 2011-04-14 Gebr. Schmid Gmbh & Co. Verfahren und Anlage zur Metallisierung von Siliziumwafern
US20110183524A1 (en) * 2008-09-30 2011-07-28 Schott Solar Ag Method for chemically treating a substrate
US8172989B2 (en) 2007-11-26 2012-05-08 Sunpower Corporation Prevention of substrate edge plating in a fountain plating process
KR101302543B1 (ko) 2012-05-18 2013-09-03 주식회사 에스이에이 도금용 태양전지 웨이퍼 지지 크라운
JP2016540369A (ja) * 2013-10-01 2016-12-22 フラウンホッファー−ゲゼルシャフト・ツァー・フォデラング・デル・アンゲワンテン・フォーシュング・エー．ファウ． 多孔性のシリコン層を連続的に製造する装置および方法

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JPH02225693A (ja) * 1989-02-27 1990-09-07 Shimada Phys & Chem Ind Co Ltd 噴流式ウエハメッキ装置
US5000827A (en) * 1990-01-02 1991-03-19 Motorola, Inc. Method and apparatus for adjusting plating solution flow characteristics at substrate cathode periphery to minimize edge effect
US5833820A (en) * 1997-06-19 1998-11-10 Advanced Micro Devices, Inc. Electroplating apparatus
US6638840B1 (en) * 2001-08-20 2003-10-28 Megic Corporation Electrode for electroplating planar structures
US20050045474A1 (en) * 1998-07-10 2005-03-03 Nolan Zimmerman Contact assemblies for electrochemical processing of microelectronic workpieces and method of making thereof

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Publication number Priority date Publication date Assignee Title
JPH02225693A (ja) * 1989-02-27 1990-09-07 Shimada Phys & Chem Ind Co Ltd 噴流式ウエハメッキ装置
US5000827A (en) * 1990-01-02 1991-03-19 Motorola, Inc. Method and apparatus for adjusting plating solution flow characteristics at substrate cathode periphery to minimize edge effect
US5833820A (en) * 1997-06-19 1998-11-10 Advanced Micro Devices, Inc. Electroplating apparatus
US20050045474A1 (en) * 1998-07-10 2005-03-03 Nolan Zimmerman Contact assemblies for electrochemical processing of microelectronic workpieces and method of making thereof
US6638840B1 (en) * 2001-08-20 2003-10-28 Megic Corporation Electrode for electroplating planar structures

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8172989B2 (en) 2007-11-26 2012-05-08 Sunpower Corporation Prevention of substrate edge plating in a fountain plating process
WO2009152896A1 (fr) * 2008-06-19 2009-12-23 Rena Gmbh Dispositif et procédé pour le traitement unilatéral par voie chimique humide et/ou électrolytique d'une matière
US20110183524A1 (en) * 2008-09-30 2011-07-28 Schott Solar Ag Method for chemically treating a substrate
US8563440B2 (en) * 2008-09-30 2013-10-22 Schott Solar Ag Method for chemically treating a substrate
US20100108525A1 (en) * 2008-11-06 2010-05-06 Andreas Krause Light-induced plating
DE102009049565A1 (de) * 2009-10-09 2011-04-14 Gebr. Schmid Gmbh & Co. Verfahren und Anlage zur Metallisierung von Siliziumwafern
KR101302543B1 (ko) 2012-05-18 2013-09-03 주식회사 에스이에이 도금용 태양전지 웨이퍼 지지 크라운
JP2016540369A (ja) * 2013-10-01 2016-12-22 フラウンホッファー−ゲゼルシャフト・ツァー・フォデラング・デル・アンゲワンテン・フォーシュング・エー．ファウ． 多孔性のシリコン層を連続的に製造する装置および方法

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