WO2008071239A1

WO2008071239A1 - Apparatus and process for single-side wet chemical and electrolytic treatment of goods

Info

Publication number: WO2008071239A1
Application number: PCT/EP2007/003746
Authority: WO
Inventors: Norbert BÜRGER; Dietmar LÜTKE NOTARP; Konrad Kaltenbach; Franck Delahaye
Original assignee: Rena Sondermaschinen Gmbh
Priority date: 2006-12-13
Filing date: 2007-04-27
Publication date: 2008-06-19

Abstract

The invention relates to the wet chemical or electrolytic treatment of planar good, i.e. a wafer, that is, according to the state of the art, treated by the aid of technically complex frames or grippers inside treatment chambers. Especially for fragile good, e.g. for solar cells made from silicon, the handling is quite time consuming, in particular if the bottom side of the good must not be wetted. According to the invention, the good 1 is placed over a vertically arranged treatment chamber 3 without frames, grippers or holders, in such a manner so that only the bottom side is wetted by the treatment fluid. By a rotational- symmetric stream 4 at the bottom side 7 of the good that is placed onto at least one support 2, the adhesion forces acting horizontally onto the good 1 neutralize each other. A lateral displacement of the good does not occur. Therefore, the commonly used limiters or lateral end stops can be omitted. According to the invention, the vertically acting components of the adhesion force cause the good 1 to adhere the supports or the contacts 2, respectively, providing a secure electrical contact for electrolytic treatment. For complete de-metallization of the contacts 2 the natural electrolyte/air boundary 25 is moved in the vicinity of the contacts by means of a gas stream 26 that is directed against the flow direction or against the level of the electrolyte. For solar cells, the metallization of contacts can be completely avoided by illumination of the bottom side that is to be electroplated, due to the contacts being located outside the electrolyte.

Description

Apparatus and process for single-side wet chemical and electrolytic treatment of goods

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. Normally, such goods are only treated single-sided at the surface. Thereby, a full surface as well as a structured treatment can occur. In order to avoid damage of the good due to chemical reactions, the backside that is not to be treated usually has to be securely protected against wetting caused by the treatment fluid. For this purpose, so called 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. Therefore, 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. Commonly, 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. During the entire treatment 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. By means of a precise vertical drive mechanism such as a stepper motor for the carrier, 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. For the present electrolytic metallization, 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. For this, 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. This apparatus according to the state of the art shows the following disadvantages:

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.

The problem of correctly levelling the good above the electrolyte surface is met by the apparatus disclosed in US 5,429,733. The good is held above the treatment chamber by means of air cushions, wherein the entire holder is mechanically connected to the treatment chamber. At the same time, the good' s upper side that must not be wet chemically treated is sealed against the treatment fluid. However, the fact that the good must be placed into and fixed by the holder is disadvantageous, since this is time consuming. After treatment completion, the good must be unloaded from the holder. In the case of fragile goods, e.g. for silicon solar cells, the danger of breakage of the thin plates is always present. The same is true during the treatment itself, if the treatment fluid streams too intensely against the clamped good that is therefore particularly subjected to the danger of breakage. However, a given minimum flow of the electrolyte streaming into the treatment chamber is necessary in order to overcome the described backflow and to contact the good' s surface for effecting a chemical modification of the same. In this context, and in particular in view of future thin substrates with increasing diameter to be wet chemically treated, also the danger of breakage of these thin goods increases dramatically. - A -

The same danger of breakage exists by using the devices for wet chemical and/or electrolytic treatment of planar goods that are described in US 5,437,777 and DE 197 36 340 C2. By means of holders, the goods are brought into contact with the treatment fluid. Seals protect the not-to-be-treated upper side of the good as well as the contact means for feeding the current into the treatment fluid. Apart from the described danger of breakage of the good, it is a further drawback that it has to be placed in the holders and must be taken out again after treatment.

These handling problems are also true for the apparatus disclosed in US 5,443,707. The holders of such an apparatus must remain at the good during the entire exposure time and several of these technically complex devices are necessary for each system in order to position the good during treatment. Spacers determine the height level with respect to the upper rim of the tank, against which the good is pressed by the holder or the transportation device. In all cases, forces are exerted onto the good which can result in breakage of the same.

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. In order to influence the stream, in particular in the border region of the wafer's bottom side, the distance H is adjusted by means of support elements in the form of screws. The same is true for the distance S that 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. However, such 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. Thus, 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.

Other 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. For this purpose, the contacts in the treatment chamber are switched anodically against a cathodic auxiliary electrode. During 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. As a result and despite several interim de- metallization steps, 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 same problem of insufficient de-metallization occurs with electroplating devices that use horizontally positioned or tilted contacts that may also serve as supports for the good. A part of these contacts is wetted by the electrolyte streaming out of the treatment chamber. Therefore, the contacts that are permanently mechanically fixed with respect to the treatment chamber become metallized up to the electrolyte/air boundary. During the electrolytic de- metallization, the above described imperfect de-metallization and cleaning appears at this boundary.

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.

In other words, 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.

In case of electrochemical or electrolytic applications, 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.

In the course of the experiments that have led to the present invention, it was initially tried to avoid the above-mentioned capillary effect of the lateral limiters or end stops by reducing the contact areas down to a line contact between limiters and the edge of the good being placed onto (a) support (s) . The partial wetting of the good's upper side could not be avoided due to the usually very low thickness of the good that results in an edge height of around 0.1 mm to 0.3 mm. This approach had to be discarded, since already small amounts of fluid can lead to undesired chemical reactions at the upper side.

However, the experiments surprisingly revealed that the lateral shear forces emerging from a fluid that streams along the surface of a good are practically controllable. A horizontal dislocation of the good away from the supports lacking lateral limiters or end stops could be avoided if the stream of the treatment fluid, at least in the vicinity of the good, was directed radial-symmetrically from the vertical line towards all sides of the treatment chamber, and if the good was positioned in congruence with the treatment chamber. By enhancing the precision, in particular with respect to the above symmetries of the experimental set-up, it was possible to sufficiently reduce the horizontal drifting of the good from its center position. 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. Although a multitude of symmetrically arranged supports were used in this experiment, 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. In the following, the technical feature of said at least one support is exemplified in an apparatus having three separate and symmetrically distributed supports.

When the good is placed over the treatment chamber onto the surface of the overflowing treatment fluid, and therefore onto the 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. Hence, since no lateral end stops are present, no wetting of the good's upper side can take place. As a further advantage, 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 treatment fluid that is permanently fed into the treatment chamber and overflows over an overflow edge of the treatment chamber into a reservoir after having contacted the good' s bottom side. By this, 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. For an electrochemical and/or electrolytic treatment of the bottom side of the good, 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. Alternatively, 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. However, 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. In order to avoid an annular build-up of metal at the electrolyte/air boundary of each contact, the apparatus according to the present invention 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. Thereby, the flow rate of the electrolyte can be nearly or exactly the same for both cases . For the movement of the electrolyte/air boundary, 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.

In case 1, 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. In case of vertically arranged contacts, 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. In case of horizontally arranged or tilted contacts, the flow direction of the gas is pointed towards the approximate center of the treatment chamber. In both cases, the electrolyte/air boundary is moved towards the treatment chamber.

The de-metallization of the anodically switched contact (s) then occurs without the good by a gas stream being shut off or choked. In this manner, the natural electrolyte/air boundary at each contact is moved from the original boundary position that exists during metallization to the outward direction. Therefore, each contact is completely wetted also in the critical boundary area by the electrolyte, and a total de- metallization takes place in the electrolytic cell that is spatially extended in absence of a gas stream.

In case 2, the displacement or movement of the electrolyte/air boundary at each contact during de-metallization takes place in the opposite direction. During the precedent metallization, the electrolyte that streams out of the treatment chamber over its overflow edge and along each contact is not affected or displaced, even though it may be sufficient to reduce the gas stream. Thus, a natural electrolyte/air boundary is formed at the contact. The de-metallization of the nearly horizontally positioned or tilted and anodically switched contact again takes place without the good. Therefore, preferably by means of a gas stream, the electrolyte/air boundary at each contact is displaced or moved from the treatment chamber towards the outside, such that the electrolyte at each contact reaches an area that has not yet been wetted during metallization. For nearly vertically arranged contacts, 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. Again, 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. Thus, 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.

According to a preferred embodiment, 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.

According to the invention, 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. For enhancement of the electrical and mechanical properties of the at least one contact that usually is made from oxidizing metals, 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.

For solar cells that preferably consist of p- and n-doped silicon, this electrical connection can be provided by illuminating the n-doped bottom side. According to its original purpose, 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.

According to a preferred embodiment of the present invention, 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. By using a treatment fluid with light activatable components in combination with a light source, the treatment process only takes place or is assisted when the light source is switched on. If desired, the activation can be selectively directed by usage of suitable masks that protect certain areas of the good's surface from being illuminated. According to another preferred embodiment, 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. 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.

In the following, the present invention is described in more detail by referring to the schematic and not-to-scale figures 1 to 9.

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.

In Figure 1, 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. Thus, 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. In this embodiment, 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. In this case, slightly less, or, for larger overhangs, no surface treatment takes place in the border region 10 of the good. Furthermore, 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. Finally, also 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.

In order to reduce costs and efforts in the case of a change of the good' s shape with respect to the fixed outer shape of the treatment chamber, 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.

In figure 1, the treatment fluid exemplarily streams centrally into the treatment chamber 3. This is symbolically represented by the flow direction arrows 4. For effecting a chemical modification of the good 1, 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. Alternatively, 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. This is achieved by rotational-symmetric (symmetrizing) means 11 such as baffles, scatter orifices, by 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. For this purpose, 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. For the purpose of adjusting the circulating amount of fluid per time unit, a drive with variable rotational speed for the pump, or adjustable chokes, valves and the like can be used inside the pipes. For a good with a treatment surface of 1.5 dm², 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. According to the invention, 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. In figure 1, 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. If desired for a specific process design, 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.

For 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. For metallization, the good 1 is cathodically switched by a bath current source 22 against the anode 21. Thus, 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. Depending on the electrolyte, in particular on its metal content, 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. For this, they are poled anodic against a cathodically switched counter electrode. In this region of the contacts 2, however, the electrolytic de- metallization is incomplete. If no other measures are taken, only a few metallization and de-metallization procedures will cause the electroplating metal to grow on the contacts in the region of the electrolyte/air boundary 25 in an almost annular or stripe-shaped form. This disturbing deposition is subsequently referred to as metal ring 31 and usually has to be removed manually, thus interrupting the automatic production process .

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. However, since for the present invention 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.

Advantageous embodiments of 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. Here, similar to the trapezoidal incisions, also 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. By incisions 18 at the overflow edge 13, the drain flow speed of the treatment fluid can thus be optimized for a given flow volume in order to ensure that the good is uniformly treated as intended. Depth and spacing of the incisions 18 are in the range of 0.5 mm to 5 mm. Depending on the process, 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. For wafers or solar cells of usual dimensions, 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. In order to avoid unequal flow volumes within the parallel fed treatment chambers 3, 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.

In this embodiment, 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. For the purpose of metallization, 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. Here, 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. In this case, 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.

In figures 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. For quadratic or rectangular goods, usually more than three contacts are used for the contacting and carrying over the treatment chamber 3. Alternatively, 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. For each of the device's contacts, 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) . By using a not depicted controlling device, 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. At least for each treatment chamber, 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. In case of using almost horizontally arranged or tilted contacts, 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. During de-metallization with the air stream choked or shut off 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.

In case of using vertically arranged contacts, 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) .

In this case, the contact mount 16 is arranged above the highest level of the electrolyte 24. Thus, 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. For complete de-metallization and cleaning of the contact from the contact metallization 30, 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. In absence of a good inside the treatment chamber, 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.

For the de-metallization of vertically arranged contacts, 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. In case of almost horizontally arranged contacts, 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. In figures 7, 8 and 9, the counter electrode (not shown) can also be the soluble or insoluble anode that is located within the treatment chamber 3. For this processing, the anode is cathodically switched against the contacts 2 that are to be de-metallized. Thus, the metal that has been dissolved from the contacts 2 and deposited onto the anode, can usefully be recycled. During the next electroplating process, it is re- dissolved from there and used for metallization of the good 1.

Figure 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. As for the other examples, 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. For such solar cells, 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. 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. These are 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 U₂ 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 dm² 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 transparent treatment chamber.

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.

Besides all common wet chemical treatments, 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.

List of reference marks

1 good, wafer, solar cell

2 support, contact

3 treatment chamber 4 flow direction arrow

5 pump

6 inlet pipe

7 bottom side of good

8 overhang 9 vertical center line

10 border of good

11 rotational-symmetric means, symmetrizing means

12 gap

13 overflow edge 14 reservoir

15 gap height

16 support mount, contact mount

17 tank wall

18 incisions 19 edge width

20 distribution pipe

21 anode

22 bath current source

23 edge of good 24 electrolyte, treatment fluid

25 electrolyte/air boundary 26 gas stream, air stream

27 opening, nozzle

28 gas distributor, gas distributor pipe

29 valve 30 contact metallization

31 metal ring

32 electrolyte distributor, distributor ring

33 reflector

34 light source 35 DC power source

36 electrical upper side contact

37 electrolytic cell

38 upper side of the good

Us solar cell voltage

U_B terminal voltage

U_z cell voltage

Claims

1. Apparatus for the exclusive single-side wet chemical, electrochemical or electrolytic treatment or for cleaning of the completely flat or structured bottom side (7) of a planar good (1), wherein the apparatus comprises: a) a vertically arranged treatment chamber (3) with at least one opening, through which a treatment fluid streams into the treatment chamber (3) and fills the same, wherein an overflow edge (13) is located at the upper rim of the treatment chamber which serves as outlet for the treatment fluid; b) at least one support (2) for the reception of the good (1) being located at the upper part of the tank wall (17) of the treatment chamber (3); c) a gap (12) being formed between the overflow edge (13) of the treatment chamber (3) and the at least one support (2) ; d) at least one means for delivering the treatment fluid into the treatment chamber (3) ; e) a reservoir (14) for collecting treatment fluid streaming out from the treatment chamber (3) through the gap (12); characterized in that: f) the gap height (15) , due to the precise positioning of the at least one support (2) in relation to the overflow edge (13), is substantially exactly the same over the entire circumference of the treatment chamber (3) ; g) the overflow edge (13) and the gap (12) run exactly horizontal along the entire circumference; h) the apparatus further comprises a centrally or annularly arranged means for feeding in of the treatment fluid at or over the bottom of the treatment chamber (3) , and/or symmetrizing means (11) located within the treatment chamber (3) , in order to direct the stream of the treatment fluid, at least in the vicinity of the good (1), radial-symmetrically from the vertical center line (9) towards all sides of the treatment chamber, thereby ensuring that almost no horizontal force which might dislocate the good (1) acts on the same.

2. Apparatus according to claim 1, characterized by a circular, quadratic, or square cross-section of the treatment chamber with or without shortened corners that enables the treatment good (1) to be positioned in congruence with the treatment chamber (3) .

3. Apparatus according to claim 1 or 2, characterized in that the supporting area of the at least one support (2) is located close to the overflow edge (13) at least almost symmetrically to the vertical center line (9) of the treatment chamber (3) , consists of electrically nonconducting or conducting materials, and carries the good once placed thereon in a sufficient distance to the overflow edge (13) so that it may be contacted by the treatment fluid.

4. Apparatus according to any of claims 1 to 3, characterized in that the overflow edge (13) has an edge width (19) of more than 0.0 mm to 5 mm, preferably 0.5 mm to 2.5 mm, and that this overflow edge (13) has, along its entire length or partially, incisions (18) of 0.5 mm to 5 mm being equally spaced from each other.

5. Apparatus according to any of claims 1 to 4, characterized in that the apparatus does not comprise any lateral end stops for keeping the horizontal position of the good after it has been placed over the treatment chamber (3) .

6. Apparatus according to any of claims 1 to 5, characterized in that it further comprises at least one electrode for electrolytic etching of the good or for the electrolytic de-metallization of the contacts (2) within the treatment chamber (3) , wherein the good and/or the contacts are switched anodic against a cathodically poled electrode by means of a suitable current source (22) .

7. Apparatus according to any of claims 1 to 6, characterized in that the at least one support (2), for an electrolytic treatment, also serves as contact for the power supply to the bottom side of the good (7) and, therefore, consists of an electrically conducting material.

8. Apparatus according to claim 6 to 7, characterized in that the cathodically poled electrode is the anode (21) .

9. Apparatus according to any of claims 1 to 8, characterized in that it further comprises at least one means to move the electrolyte/air boundary (25) that is naturally formed at the at least one contact (2) during electrolytic metallization of the good (1) and the contact, or during electro- lytic de-metallization of the at least one contact.

10. Apparatus according to claim 9, characterized in that said means are selected from the group consisting of (a) at least one gas stream (26) , (b) means to lower the at least one contact into the treatment fluid, (c) means to locally apply treatment fluid onto said at least one contact, (d) means to elevate the overflow edge, and/or (e) means to elevate the level of the treatment fluid by increasing its flow .

11. Apparatus according to claims 9 or 10, characterized in that said means to move the electrolyte/air boundary is at least one gas distributor (28) with at least one opening

(27) being located at and directed to the at least one contact (2) and/or the surface of the electrolyte (24) contained in the treatment chamber (3) in such a manner that the electrolyte/air boundary (25) at the at least one contact is movable in relation to the natural electrolyte/air boundary by means of the gas stream (26) emanating from each opening (27) .

12. Apparatus according claim 11, characterized in that the gas distributor (28) comprises a valve (29) , that is open towards the treatment chamber (3) during metallization of the good in order to move the natural electrolyte/air boundary (25) at the at least one contact (2) , and that is closed or choked during the subsequent electrolytic de- metallization of the at least one contact (2) .

13. Apparatus according to claim 11, characterized in that the gas distributor (28) comprises a valve (29) that is open from the treatment chamber (3) towards the outside during de-metallization of the at least one contact (2) in order to move the natural electrolyte/air boundary (25) at the at least one contact (2), and that is closed or choked during electrolytic metallization of the good (1) and the at least one contact (2) .

14. Apparatus according to any of claims 6 to 13, characterized in that the at least one contact (2) has a surface that is covered with an electrically conductive diamond layer and/or partially covered with an electrically insulating layer.

15. Apparatus according to any of claims 1 to 14, characterized by a plurality of treatment chambers (3) being arranged side by side and/or one after another in a production facility, having a common reservoir (14) and a means that feeds the treatment chambers with treatment fluid by means of a distribution pipe (20) , wherein groups of this arrangement are simultaneously loadable and unloadable with the good (1) by means of a transportation device.

16. Apparatus according to any of claims 1 to 15, characterized in that it further comprises at least one transporting means for conveying the good (1) to and from the treatment chamber (3) , with means for positioning and placing the good onto the at least one support (2) over the treatment chamber and for its repositioning and picking up after the treatment .

17. Apparatus according to any of claims 6 to 16, characterized in that it further comprises a soluble or insoluble anode (9) that also serves as a counter electrode during the de- metallization of the at least one contact (2) .

18. Apparatus according to any of claims 6 to 17, characterized in that it further comprises a bath current source (22) for generating direct current, or unipolar or bipolar pulsed current.

19. Apparatus according to any of claims 6 to 18, characterized in that it further comprises at least one light source (34) for the activation of light sensitive components of the treatment fluid and/or for effecting chemical, electro- chemical or electrolytic processing.

20. Apparatus according to any of claims 6 to 19, characterized in that the good (1) to be treated is a solar cell and that the apparatus further comprises a light source (34) located within or outside the electrolyte (24) in order to illuminate said good during metallization.

21. Apparatus according to claim 20, characterized in that it further comprises at least one electrical contact (36) located outside the electrolyte (24) for feeding the electroplating current from the bath current source (22) to the good (1) .

22. Process for the exclusive single-side wet chemical, electrochemical or electrolytic treatment or for cleaning of the completely flat or structured bottom side (7) of a planar good (1) with a treatment fluid, wherein the upper side of the good is not protected against being wetted, comprising the following steps: a) providing a vertically arranged treatment chamber (3) having a circular, quadratic, or square cross-section with or without shortened corners, wherein the chamber has at least one opening, through which the treatment fluid streams into the treatment chamber (3) and fills the same, and wherein an overflow edge (13) is located at the upper rim of the treatment chamber which serves as outlet for the treatment fluid; b) effecting chemical modification of the good (1) by- contacting the same with the treatment fluid that is permanently fed into the treatment chamber (3) and overflows over an overflow edge (13) of the treatment chamber into a reservoir (14), wherein the treatment fluid is fed in a circular flow; c) transporting, positioning of the good in congruence with the treatment chamber (3) , and placing the good (1) onto at least one support (2) by means of a transportation device, wherein the at least one support is distributed along the overflow edge (13) of the treatment chamber; d) forming a gap (12) between the overflow edge (13) and the bottom side (7) of the good placed onto said at least one support (2); e) removing the transportation device from the good, so that no means for protecting the upper side against being wetted is present; characterized in that the process further comprises the following steps: f) adjusting the quantity of treatment fluid flowing through the treatment chamber (3) in such a manner, that the upper side of the good being placed onto the surface of the treatment fluid and positioned in a certain height by means of said at least one support (2) is not wetted; g) allowing the treatment fluid to stream out of the treatment chamber (3) through the gap (12), wherein said stream contacting the good's bottom side (7), at least in the vicinity of the good (1), is directed radial- symmetrically from the vertical center line (9) towards all sides of the treatment chamber (3) in such a manner, that the horizontal components of the force of adhesion between good and treatment fluid almost neutralize each other, and that the vertical components of adhesion between good and treatment fluid at the border of the good (10) cause the good (1) to be adhered to the at least one support (2); h) stabilizing the position of the good that is placed onto the at least one support (2) in relation to the treatment chamber (3) by means of the streaming treatment fluid and by friction against the at least one support (2) in such a manner, that almost no horizontal force which might dislocate the good (1) acts on the same.

23. Process according to claim 22, characterized in that the current necessary for the electrolytic treatment of the good is applied by means of at least one electrically conductive contact.

24. Process according to claim 23, characterized in that the at least one support (2) is electrically conductive and used as the at least one contact.

25. Process according to any of claims 23 to 24, characterized in that the electrolyte/air boundary (25) that is naturally formed at the at least one contact (2) during electrolytic metallization of the good and the contact, or during the electrolytic de-metallization of the contact, is moved.

26. Process according to claim 25, characterized in that, during metallization, the electrolyte/air boundary (25) at the at least one contact (2) is sufficiently moved back by means of at least one gas stream (26) directed to the surface of the electrolyte (24) or against the natural flow direction of the electrolyte at the contact, such that, during subsequent de-metallization of the at least one contact (2) with the gas stream being choked or shut off, the electrolyte/air boundary (25) formed during metalliza- tion is entirely positioned within the electrolyte.

27. Process according to claim 25, characterized in that, during de-metallization of the at least one contact (2), the electrolyte/air boundary (25) at the contact (2) is sufficiently moved by (a) means of at least one gas stream (26) that is directed 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 into the treatment fluid, (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, and/or (e) elevating the level of the treatment fluid by increasing its flow, such that the natural electrolyte/air boundary (25) that is formed during previous metallization is entirely positioned within the electrolyte at least in the vicinity of the at least one contact (2) .

28. Process according to any of claims 22 to 27, characterized in that an anodic de-metallization of the at least one contact is effected subsequent to electrolytic metallization by using the anode (21) appropriately switched to act as cathode.

29. Process according to any of claims 22 to 28, characterized in that the treatment fluid is guided to stream radial- symmetrically along the bottom side (7) of the good by (a) using rotational-symmetric means (11, 21), (b) annularly or centrally feeding in of the treatment fluid into the bottom of the treatment chamber (3) , and/or (c) using multiple symmetrical means for feeding in of the treatment fluid into the bottom part of the treatment chamber (3) .

30. Process according to any of claims 22 to 29, characterized in that the draining speed of the treatment fluid circulating with a given flow rate is varied by means of incisions (18) at the overflow edge (13) .

31. Process according to any of claims 22 to 30, characterized in that the electrolytic treatment of the good is effected by using direct current, or unipolar or bipolar pulsed current .

32. Process according to any of claims 22 to 31, characterized in that the planar good (1) to be treated is a solar cell and that the electrolytic treatment of said solar cell is effected by illuminating its bottom side (7) .

33. Process according to claim 32, characterized in that the electrical contacting of the good is effected outside the electrolyte .

34. Process according to any of claims 22 to 33, characterized in that at least one light source (34) located within the treatment chamber (3) is used for the activation of light sensitive components of the treatment fluid and/or for effecting or assisting a chemical, electrochemical or electrolytic processing.

35. Use of the process as defined in any of claims 22 to 34 for the electro plating of solar cells made from silicon.