Apparatus for wet processing of planar workpiece, device for cell of the apparatus and method of operating the apparatus

Abstract

To provide a device for a cell of an apparatus for wet processing of workpieces that enables processing of relatively thin workpieces while holding the workpieces relatively well in a single plane.SOLUTION: This object is achieved according to a first aspect by the device according to the invention, which is characterized in that channels are provided through walls, each channel arranged to conduct liquid to a respective one of the apertures.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a device for a cell of an apparatus for wet processing of flat workpieces, comprising: a structure including a first wall and a second wall; the workpiece is movable in a first direction within the central plane through a space between the first wall and the second wall; openings for introducing pressurized liquid between the first wall and the second wall are provided facing the central plane on opposite sides of the central plane; the openings are distributed in a first direction and in a second direction transverse to the first direction; discharge openings for exiting the space are defined along the extent of the space in the first direction and on opposite sides of the space as viewed in the second direction; The first wall and the second wall relate to a device that forms a barrier to the flow of liquid from the space in a direction perpendicular to the central plane.

[0002] The present invention also relates to an apparatus for wet processing flat workpieces.

[0003] The present invention also relates to a method of operating such an apparatus.

[0004] The invention also relates to the use of such a device and at least one of such apparatuses.

[0005] Background technology U.S. Patent Application Publication No. 2015 / 0252488 discloses a plater for wet-chemical electrochemical processing in which a metal is electrochemically deposited on the surface of a material to be processed. The device has side walls arranged laterally and extending parallel to the transport direction of the material to be processed, and a bottom wall defining a processing chamber. The processing chamber is further closed transversely to the transport direction by a further side wall having a slot for transporting the material to be processed. A pair of squeeze rollers is arranged in these slots to seal the liquid processing chamber against the outflow of processing liquid, and the material to be processed is guided between the squeeze rollers when being transported into or out of the processing chamber. The material to be processed is transported by wheels mounted on axles spaced a fixed distance from each other, the axles extending transversely to the transport direction. Anodes are arranged above and below the material to be processed. A transport surface extends in the processing chamber in the transport direction. As viewed from the transport surface beyond the anodes, supply devices with nozzles are located above and below the material to be processed. The supply device, formed by a top conduit and a bottom conduit, transports the treatment liquid to the surface of the material being processed through nozzles on both sides. The nozzles and the remaining components are located below the water level of the treatment chamber. There is no wall above the supply device, which is located above the material being processed during use. The anodes do not form a barrier to liquid flow from the space between the anodes in a direction perpendicular to the central plane. The wheels transporting the material being processed contact the material being processed at positions along its entire width. This is undesirable when the material being processed is relatively fragile, such as when it is covered by a photomask. If the wheels were omitted, a relatively large distance must be maintained between the anode and the material being processed to prevent the material from contacting the anode. Even so, unevenness across the width of the material being processed can cause the distance between the anode and the material to vary, leading to uneven coating formation.

[0006] German Patent Application Publication No. 4229403 discloses an apparatus capable of plating the upper and lower surfaces of a thin plastic foil with through holes, as well as the side surfaces of the through holes. A plating chamber is provided with a housing, the inlet of which is formed by a pair of squeezing rollers, and the outlet is also formed by a pair of squeezing rollers. An upper anode and a lower anode extend parallel to and spaced apart from the plastic foil above and below it. Respective electrolyte distribution spaces are provided between the anodes and the plating chamber housing. The anodes are provided with a plurality of through holes that are inclined relative to the direction of movement of the plastic foil, so that they converge in the direction of movement. Electrolyte supplied to the distribution spaces through a conduit enters the space between the anode and the plastic foil with a movement component parallel to the direction of movement of the plastic foil. The electrolyte flows out of a side opening in the housing and enters a liquid reservoir of the apparatus. The side opening is provided at only one location along the length of the chamber. The plastic foil is unwound on reels at either end of the device, wound up and held tightly flat by a pair of squeeze rollers, so this arrangement is only suitable for processing endless foils, which require tight contact between the squeeze rollers and the foil across the width of the foil.

[0007] WO 98 / 49374 discloses an apparatus for electrolytically treating circuit boards and foils in a horizontal continuous system using direct or pulsed current. The apparatus includes an upper insoluble anode and a lower insoluble anode, which function as counter electrodes. The electrolytic cell is formed by the upper anode, the circuit board or foil, and an electrolyte space therebetween. The anodes extend essentially across the entire width of the workpiece. The circuit board or foil is transported between the upper and lower anodes by upper and lower guide elements, preferably centrally conductive, and by clamps that also function as electrical contact elements. The guide elements are typically narrow, electrically insulated spindles on which perforated disks made of non-conductive plastic are mounted. An electrolyte spray device is positioned outside the electrolyte space on the side of the counter electrode opposite the transport surface. The spray tube is provided with holes or nozzles oriented perpendicular or at a predetermined angle to the surface of the workpiece. The anode is perforated and positioned so that treatment liquid exiting the spray tube holes or nozzles can pass through the anode substantially or completely unimpeded. However, the anode does not form a barrier to prevent liquid flow from the conveying surface in a direction perpendicular to the conveying surface. The spray tubes are positioned sufficiently far from the top and bottom walls of the device. Therefore, a perforated disk is required to hold the circuit board or foil to the conveying surface.

[0008] A similar configuration to that shown in WO 98 / 49374, but without a perforated disk on the spindle, is used in a horizontal continuous plating apparatus currently available from the applicant. In this apparatus, spray bars are located on opposite sides of a plane along which the workpiece is transported and are directed toward the plane. The distance from the spray bars to the workpiece's moving surface is relatively small. Therefore, there is a risk that a thin-walled workpiece may undulate and contact the contact protection grid located between the anode and the moving surface. In the case of dry thin-film electroplating, this could result in the photomask being dislodged from the workpiece. Even if contact is avoided, the formation of one or more relatively rigid metal layers on one or more surfaces of the workpiece can fix the undulations.

[0009] Summary of the Invention It is an object of the present invention to improve devices, apparatus and methods of the type defined in the opening paragraph above so that relatively thin workpieces can be processed while maintaining the workpieces relatively well within a single plane.

[0010] This object is achieved, according to a first aspect, by a device according to the invention, characterized in that passages are provided through the wall, each passage being arranged to conduct the liquid to a respective one of the openings.

[0011] The device may be configured to form a complete cell or to be placed in a tank to form a cell. In the latter case, the space allowing access to the liquid introduced between the opposing surfaces of the first and second walls is larger than the spatial section between these opposing surfaces. In one embodiment, multiple devices can be provided in a single tank to form a cell. The type of processing can include, in particular, wet chemical processing, such as at least one of chemical or electrolytic metal deposition, chemical or electrolytic etching, and chemical or electrolytic cleaning. At least a portion of the liquid introduced through the opening contains a reactant, so that the flow of liquid over the surface of the workpiece replenishes the reactant, thereby resulting in more efficient processing. Surface processing of the workpiece can be performed on only one surface or both surfaces of the workpiece, with the flow of liquid present across both surfaces.

[0012] In one embodiment, the device is for forming a cell configured to electroplate, for example pulse plate, a workpiece.

[0013] The workpiece may be a plate or foil. The workpiece may be a separate plate or foil piece, as opposed to a foil that is transported from reel to reel through the apparatus. The device is particularly suited to apparatuses for processing relatively thin, relatively flexible, flat workpieces, e.g., having thicknesses on the order of 10-100 μm, because such workpieces are more prone to bending. However, the device may also be used in apparatuses for processing thicker workpieces.

[0014] The workpiece is movable in a first direction within a central plane between the first and second walls. The first direction, also referred to herein as the longitudinal direction, is defined simply by the direction of movement. The first direction does not necessarily correspond to the largest dimension of the device or the space into which the liquid is introduced.

[0015] The device includes a structure including a first wall and a second wall. The first and second walls need not be joined or form part of a single assembly. However, the first and second walls are attached to present opposing surfaces that define at least a portion of a space accessible to a liquid introduced between the walls. A liquid-permeable structure can be inserted between the walls. However, the walls are impermeable to liquid except for the passageway, thereby forming a barrier. The first and second walls function as a backflow barrier to the opening for introducing liquid into the space between the walls. Thus, the first and second walls form part of the boundary of the space accessible to a liquid introduced between the walls. Such liquid is prevented from flowing directly from the sides of the first and second walls closest to the central plane to the opposite rear sides of the first and second walls, but the liquid can be collected and returned as pressurized liquid by a recirculation system including at least one pump.

[0016] Passages are provided through the first and second walls, each of which is arranged to direct liquid to a respective one of a plurality of openings for introducing liquid into the space between the first and second walls. The openings for introducing liquid are provided on opposite sides of the central plane and facing the central plane. Thus, the flow direction is primarily toward the discharge opening, and otherwise toward the central plane near the openings. To establish such a flow field, openings can be defined in the surface at the end of each passage. If the openings are defined at the distal ends of nozzles protruding from the surface, these nozzles protrude a relatively short distance from the surface so that the associated wall still functions as a backflow barrier.

[0017] The openings are distributed in a first direction and a second, or transverse, direction so that pressurized liquid is introduced at multiple locations across the wall surface. This accelerates the flow of liquid in the opposite transverse direction toward the discharge openings. During operation, the discharge openings are located at the side edges of the workpiece moving through the device. Depending on the extent to which the space through which the workpiece can move is closed at its longitudinal ends, flow in the first direction is limited or nonexistent.

[0018] A section of a flat workpiece that deviates from the central plane toward one of its opposing surfaces locally narrows the already narrow gap between that surface and the workpiece. This pinches the flow, causing a local increase in pressure. Pressure also locally decreases on the opposite side of the workpiece. The resulting force tends to return the workpiece section toward the central plane. This restoring effect cannot be achieved with a nozzle that directs a diverging jet toward the workpiece surface, because a workpiece section moving toward the nozzle orifice is subjected to a localized impingement but experiences no net force returning the section to the central plane. This is because there is no backflow barrier immediately behind the nozzle.

[0019] In contrast, in the present device, the workpiece is maintained substantially in the central plane by the flow of liquid on either side. As a result, the space in which the workpiece can move can have a relatively low height. Therefore, the amount of liquid to be circulated is relatively small, making the device relatively compact. Unintentional contact between the surface of the workpiece and the device is avoided. Solid guide elements that contact the surface of the workpiece away from the side edges of the workpiece can be omitted, at least between the longitudinal ends of the device. The workpiece does not need to be held under a second lateral tension.

[0020] The liquid discharge openings are defined on opposite sides of the space in the second direction and are provided along the extent of the space in the first direction, so that the flow of liquid is directed laterally outward from the middle to both sides. If the flow was only from one edge of the workpiece to the opposite edge in the second direction, thin-walled workpieces would begin to flap like a flag in the wind, especially if the workpieces were supported by only one of their edges.

[0021] As mentioned above, in one embodiment of the device, openings are defined in the surfaces of the first and second walls at the ends of each passageway.

[0022] That is, the passage is essentially a through-hole between the first and second walls. The passage end of the opening is at least flush with the surface of the wall. This first helps to establish the desired flow field. Second, it allows the first and second walls to be positioned closer together.

[0023] One embodiment comprises a first liquid distribution device and a second liquid distribution device, the first wall and the second wall comprising a wall of the first liquid distribution device and a wall of the second liquid distribution device, respectively, and the liquid distribution devices are mounted such that a space extends between the liquid distribution devices.

[0024] This embodiment has relatively few parts.

[0025] In one embodiment of the device, at least one liquid distribution space extending in a second direction across the entrance to the passage is defined in at least one of the first wall and the second wall on a side opposite the space.

[0026] In particular, a first liquid distribution space may be present on the side of the first wall opposite the side facing the central plane, and a second liquid distribution space may be present on the side of the second wall opposite the side facing the central plane. When the device includes a first liquid distribution device and a second liquid distribution device, the liquid distribution spaces may be defined within the respective chambers of the liquid distribution devices. The liquid distribution spaces equalize the liquid pressure upstream of the passages that pass through the first and second walls. Thus, each liquid distribution space generally extends in a first direction and a second direction across the inlets of the multiple passages. For example, each liquid distribution space may extend substantially over a predetermined range in the first and / or second direction of the wall on which the liquid distribution space is defined.

[0027] In a particular example of this embodiment, the liquid distribution space is defined by a barrier that is inclined relative to the wall such that the liquid distribution space tapers towards the edge of the wall.

[0028] This has the advantage that liquid need only be introduced into the liquid distribution space on one side of the liquid distribution space. Liquid can be introduced through one or more elongated openings extending in a first or second direction at or near, and generally parallel to, one edge of the liquid distribution space. The liquid distribution space decreases in height (relative to the first or second wall) toward the opposite edge. As a result, a relatively uniform exit velocity of liquid across the openings is achieved without providing liquid inlets for pumping liquid into the liquid distribution space along multiple edges of the liquid distribution space.

[0029] An example embodiment of a device in which a liquid distribution space is defined on the opposite side of at least one of the first and second walls relative to the space includes at least one expanding liquid conduit having an inlet on one side connectable to a liquid supply conduit and expanding toward an opposite side where the expanding liquid conduit is in liquid communication with the liquid distribution space at multiple points along the width of the expanding liquid conduit.

[0030] This embodiment requires only a limited number of connections from the pump to the tubular conduit carrying the liquid. Nevertheless, uniform flow along the edges of the liquid distribution space is achieved. In one embodiment, the diverging conduit can be provided with flow guides along at least a portion of its length, for example at the wider end of the diverging conduit. This helps to avoid turbulence. Liquid communication with the liquid distribution space at multiple points along the width of the diverging liquid conduit can be via multiple separate openings distributed along the width of the diverging liquid conduit. Alternatively, a single opening can extend along most of the width of the diverging liquid conduit, for example along substantially the entire width corresponding to at least 90% or at least 95% of the width of the diverging liquid conduit.

[0031] In this example embodiment of a device comprising a first liquid distribution device and a second liquid distribution device, where the first wall and the second wall comprise the wall of the first liquid distribution device and the wall of the second liquid distribution device, respectively, and the liquid distribution devices are attached so that a space extends between the liquid distribution devices, the expanding liquid conduit and liquid distribution space are defined within a chamber in the housing of one of the first liquid distribution device and the second liquid distribution device by a barrier extending into the chamber.

[0032] This results in a compact construction with fewer sealing connections between different components and therefore a lower risk of leakage.

[0033] In one embodiment of the device, at least one of the discharge openings is formed by a single gap extending along the first extent of the space between opposing liquid-impermeable portions, for example between an edge of a first wall and an edge of a second wall.

[0034] The edge section of the workpiece can be held outside the space between the first and second walls by extending through the discharge opening, or at least a portion of the transport device for holding the workpiece by the edge of the workpiece can extend through the discharge opening into the space between the first and second walls. In the latter case, the portion holding the workpiece can be effective for moving the workpiece longitudinally within the device. In the former case, the portion holding the workpiece can at least support the workpiece as it moves within the device, but the portion holding the workpiece can also move the workpiece within the device.

[0035] In one embodiment, each discharge opening has a height of at most 100 mm, for example at most 50 mm or even less than 40 mm.

[0036] In this context, the term height refers to the dimension across the central plane.

[0037] The relatively low height allows the effect of returning the workpiece section to the central plane when it has moved away from the central plane to be achieved with a flow velocity of at most 10 m / s, for example less than 8 m / s or even less than 5 m / s. The minimum flow velocity can be, for example, 0.1 m / s or 0.5 m / s.

[0038] One embodiment further comprises at least one liquid-permeable electrode, for example a flat electrode, extending in a plane between the central plane and one of the first wall and the second wall.

[0039] This embodiment is for an electroplating cell. In particular, there may be a first liquid-permeable electrode, e.g., a first flat electrode, extending in a plane between the central plane and the first wall, and a second liquid-permeable electrode, e.g., a flat electrode, extending in a plane between the central plane and the second wall. Even with relatively thin workpieces, the risk of approaching one or more electrodes due to unevenness is relatively low. This reduces the risk of damage due to physical contact and ensures uniform plating thickness. In one embodiment, the electrodes may be provided with a mesh. Each electrode may be subdivided into electrically insulated segments located in the plane of the electrode. Examples of such configurations and their effects are described, for example, in WO 2003 / 018878.

[0040] One embodiment further comprises at least one liquid-permeable shielding structure, for example a flat shielding structure, extending in a plane between the central plane and one of the first wall and the second wall.

[0041] In one embodiment, such shielding structures are provided on each side of the central plane. If an electrode is provided on each side of the plane, the shielding structures are positioned between the central plane and the electrode. Contact between the surface of the workpiece and the electrode is therefore prevented under all circumstances. Otherwise, such contact would lead to a short circuit, since one of the workpiece and the electrode typically forms the anode and the other the cathode. Each shielding structure is typically a solid structure closest to the central plane on the side of the central plane on which it is provided. Each shielding structure can be made of an electrically insulating material, such as a polymer material. One way to implement the shielding structure is to provide a plate of electrically insulating material with a relatively large number of relatively small-diameter through-holes. The areal density of such holes is at least an order of magnitude greater than the areal density of openings in the first and second walls. The diameter of the holes is correspondingly smaller. To achieve a uniform current density, two or more adjacent holes at a particular location can be connected by removing the material that would otherwise separate them. Alternatively or additionally, one or more holes may be blocked. In one example, in a device intended for use with workpieces having a thickness of less than 1 mm, e.g., less than 100 μm or even less than 50 μm, the distance between the central plane and the shielding structure is between 2 mm and 15 mm, e.g., less than 10 mm or even less than 8 mm. One or more shielding structures are particularly useful when processing discrete, flat workpieces (i.e., sheets rather than continuous webs) because the workpieces enter the cell with a free edge that is essentially unsupported. A section of the workpiece at that edge may curve in the direction of travel.

[0042] In one embodiment of the device, the first wall and the second wall are provided with nozzles that extend into the opening.

[0043] Typically, a respective nozzle is provided for each opening. The nozzles may be formed in the wall, or they may be separate devices inserted into holes in the wall and fixed in position relative to the wall. Typically, the openings correspond to the outlet orifices of the nozzles. However, in one embodiment, the outlet orifices of the nozzle devices may be somewhat recessed relative to the openings formed in the surface of the wall. The nozzle devices may protrude slightly from the holes in which they are located. However, separate nozzle devices completely fill the holes in the wall into which they are inserted. Therefore, if separate nozzle devices are provided, the liquid cannot bypass these nozzle devices inserted through the first and second walls. The nozzles make it possible to shape the flow of liquid entering the space, since they are different from cylindrical passages.

[0044] In a particular example of this embodiment, the orifice of the nozzle has an elongated shape with a larger dimension in the second direction than in the first direction.

[0045] This has the effect of providing the necessary tangential flow field (from the center outward to the discharge openings along the surface of the workpiece) without requiring an excessive reduction in the spacing between the openings, particularly in the first direction. A relatively uniform coverage of the workpiece surface with liquid is achieved. The nozzle may, for example, be a fan nozzle, i.e., a nozzle with a slit-shaped orifice. In a specific example of this embodiment, the device also includes at least one liquid-permeable electrode, e.g., a flat electrode, extending in a plane between the central plane and one of the first and second walls, and the electrode includes an elongated liquid-permeable window, e.g., an opening, aligned with each nozzle orifice. In this embodiment, the liquid-permeable window in the electrode may have a relatively small area. Because the electrode is non-conductive where the window is provided, fewer compensation measures are required to account for the non-conductive window. In particular, if a shielding structure is also provided between the electrode and the central plane, the shielding structure may require less adaptation to achieve a uniform current density across the area of ​​the workpiece.

[0046] In one embodiment of the device, the openings are arranged in rows extending at least approximately in the second direction.

[0047] This contributes to providing uniform flow from the center to the discharge openings. Typically, there are at least three openings in each row, for example, at least five or at least ten openings. The openings are aligned so that each row extends in a straight line. The openings are aligned in rows that extend essentially in the second direction (within normal manufacturing tolerances), so that the rows extend parallel to one another.

[0048] In example embodiments in which the apertures are arranged in rows extending at least generally in the second direction, the apertures are uniformly distributed within each row.

[0049] That is, the spacing between apertures is at least approximately the same for all apertures in a row, and there are at least three apertures in each row. In one embodiment, the spacing is the same for a plurality, for example a majority, of the rows.

[0050] In a particular example of an embodiment in which the apertures are aligned in rows extending at least approximately in the second direction and the apertures are uniformly distributed within each row, the apertures in each row are offset in the second direction relative to the apertures in at least one other row.

[0051] This helps to avoid streaks in the first direction in which the workpiece is subjected to electrochemical processing.

[0052] In a particular example of an embodiment in which the apertures are aligned in rows extending at least approximately in the second direction, the apertures are uniformly distributed within each row, and the apertures in each row are offset in the second direction relative to the apertures in at least one other row, the apertures are aligned in columns extending at an acute angle to the first direction.

[0053] Thus, a compromise is achieved between establishing a substantially uniform flow field and preventing streaks on the workpiece.

[0054] In one embodiment of the device, the first wall and the second wall are: (i) 1 m 2 and (ii) a linear density of at least 16 openings per meter in the second direction (x).

[0055] One advantage is that relatively thin, discrete workpieces (i.e., sheets rather than continuous webs) having thicknesses on the order of 1-100 μm, e.g., 5-50 μm, can be processed while maintaining a relatively good central plane, particularly in devices configured such that the central plane (here, the transport plane) is a substantially horizontal plane.

[0056] For devices configured for use in an apparatus in which the central plane is a substantially vertical plane, the first wall and the second wall are: (i) 1 m 2 The workpiece may have apertures in at least one of (i) an areal density of at least 230 apertures per meter and (ii) a linear density of at least 8 apertures per meter in the second direction (x). Reducing the number of apertures reduces the manufacturing cost of the device. When the central plane, i.e., the transport plane, is a substantially vertical plane, gravity helps to return sections of the workpiece that have moved out of plane back into the plane. Therefore, fewer apertures are required for a workpiece of a given thickness.

[0057] According to another aspect, an apparatus for wet processing flat workpieces according to the invention comprises at least one device according to any one of the claims.

[0058] The apparatus comprises one or more cells, at least one of which comprises one or more devices according to the invention, and the types of processing performed can differ between the cells.

[0059] The apparatus may include at least one pump for pumping liquid to the opening of the or each device according to the present invention. The pump thus acts as a source of pressurized liquid. The apparatus may be configured to drive the or each pump to achieve a certain minimum flow rate at the or each device outlet opening.

[0060] In one embodiment of the apparatus, in which the device is one in which at least one of the discharge openings is formed by a single gap extending between opposing liquid-impermeable portions along the first directional extent of the space between the surfaces, for example between an edge of a first wall and an edge of a second wall, the apparatus further comprises a conveying device comprising at least one clamp releasably engaging the workpiece at an edge of the workpiece and guided to move along the length of the gap, and at least one drive for moving the conveying device.

[0061] Thus, the workpiece need only be contacted at one or both of its side edges to move through the device. In one embodiment, the apparatus can include a series of two or more devices of the type described above and a single transport device for moving the workpiece through the entire series of devices. The transport device is guided to move in a first direction.

[0062] According to another aspect, a method of operating an apparatus according to the present invention includes pumping a liquid through the opening and the discharge opening while moving a workpiece in a central plane through the device.

[0063] As the workpiece moves through the device, it is held substantially at the central plane by the action of the liquid flowing along the surface of the workpiece. In particular, the liquid is pumped at a velocity sufficient to ensure that any section of the workpiece moving from the central plane toward one of the first and second walls experiences a localized force tending to return that section toward the central plane. The workpieces are discrete workpieces, i.e., sheets, rather than a continuous or quasi-continuous web. The workpieces are typically panels or foils.

[0064] According to another aspect, the present invention provides the use of a device and / or apparatus according to the present invention for manufacturing a semiconductor device, for example an optoelectronic device.

[0065] The device and / or apparatus can be used, inter alia, to fabricate photovoltaic devices. Such devices can be flexible devices. The device and / or apparatus can be used, for example, to fabricate interconnects in a damascene electroplating process and / or to fill trenches and / or vias, for example.

[0066] In certain embodiments, the device and / or apparatus is used to deposit one or more device or precursor layers on a substrate, such as a silicon substrate, a glass substrate coated with a transparent conductive oxide (TCO) such as tin oxide (e.g., fluorine-doped tin oxide FTO, indium tin oxide ITO), or a molybdenum-coated stainless steel substrate. When the device and / or apparatus is used to deposit a device or precursor layer, the workpiece can then be subjected to further processing steps in a controlled atmosphere, such as annealing, laser scribing, photoresist patterning, etc. In this regard, it is useful that the workpiece can be relatively thin, yet can be a separate workpiece. Roll-to-roll processing is not required to deposit the device layer or the precursor layer used to form the device layer.

[0067] Both an absorber layer (or their precursor) and a support layer can be deposited.

[0068] Photovoltaic devices that can be produced by this method include CdS / CdTe-based solar cell devices, solar cell devices incorporating solar cell substrates such as ZnTe, ZnSe, ZnS, ZnO, and solar cell devices based on doped silicon surfaces with plating bases such as CuInSe, CuZnSnS, or CuInGaSe, or indium-doped tin oxide. These and further examples are disclosed, for example, in EP 2709160. [Brief explanation of the drawings]

[0069] The invention will now be explained in more detail with reference to the accompanying drawings. [Figure 1] 1 is a cross-sectional view of a portion of a cell for electroplating a flat workpiece. [Figure 2] FIG. 2 is a detailed schematic cross-sectional view showing a portion of a cell and the flow direction of electrolyte circulating within the cell. [Figure 3]FIG. 1 is a plan view of one of two walls through which a workpiece can be moved through the cell. [Figure 4] FIG. 1 is a cross-sectional plan view of one of two liquid distribution devices forming part of a cell.

[0070] Description of the embodiment The device 1, intended to form part of a cell of an apparatus for wet processing of flat workpieces, comprises a first liquid distribution device 2a and a second liquid distribution device 2b.

[0071] It is convenient to define a first direction y, also referred to herein as the longitudinal direction, and a second direction x, transverse to the longitudinal direction y, also referred to herein as the transverse direction (FIG. 4). In use, a flat workpiece is guided in the first direction y (FIG. 4) through the space 3 (FIG. 1) between the liquid distribution devices 2a, 2b. The workpiece extends substantially in a central plane 4 (FIG. 2) intermediate the first and second liquid distribution devices 2a, 2b. In this example, the central plane 4 is a generally horizontal plane.

[0072] In the illustrated example, the device 1 is intended to form part of an electroplating cell and therefore further comprises a first anode 5a and a second anode 5b, and a first shielding structure 6a and a second shielding structure 6b.

[0073] The shielding structures 6a, 6b can comprise, for example, a grid made of an electrically insulating material, such as a polymer material. The shielding structures 6a, 6b are liquid-permeable. The anodes 5a, 5b can be made, for example, of a metal, mesh, or other electrically conductive grid structure. Thus, the anodes 5a, 5b are also liquid-permeable.

[0074] Although two anodes 5a, 5b are shown in the drawings, these anodes 5a, 5b need not extend beyond the space 3 in the first direction y. Instead, there may be a series of anodes in a single plane, one after the other in the first direction y. Furthermore, each anode 5a, 5b may be subdivided into segments that are electrically insulated from one another in the second direction x.

[0075] The conveying device 7 (FIG. 1) is shown only very diagrammatically. The conveying device 7 comprises a clamp 8 for holding a workpiece at one side edge of the conveying device 7. A plurality of such conveying devices 7 can be provided for holding the workpieces. A drive 9 is arranged to move the conveying device 7 in a first direction. The drive 9 can be, for example, an endless belt or an endless chain. In the electroplating process, the workpiece acts as a cathode. The or each clamp 8 is arranged to be in electrical contact with the workpiece to establish a voltage difference between the workpiece and the anodes 5a, 5b.

[0076] In the illustrated embodiment, the workpiece is held by only one edge. In other embodiments, the workpiece may be held by both opposing edges as viewed in the second direction x. In particular, the workpiece may be driven by a wheel or belt that extends across the space 3 in the second direction x and contacts the workpiece at its edges.

[0077] Each of the liquid dispensing devices 2a, 2b comprises a housing with a liquid inlet 10a, 10b for connection to a respective liquid supply conduit 11a, 11b. One or more pumps (not shown) are provided for pumping liquid through the liquid supply conduits 11a, 11b.

[0078] The chambers 12a, 12b are defined by housings. Each composite wall 13a, 13b includes a respective housing wall 14a, 14b and an additional wall 15a, 15b disposed on the housing wall 14a, 14b. At least opposing surfaces of the walls 13a, 13b are substantially parallel to the central plane 4, as are the anodes 5a, 5b and the shielding structures 6a, 6b. The component walls 14, 15 of each composite wall 13a, 13b can be made of different materials. For example, the additional walls 15a, 15b can be made of an electrically insulating material. The housing walls 14a, 14b can be made of a mechanically strong material. In an alternative embodiment, the additional walls 15a, 15b are omitted. As long as the composite walls 13a, 13b form a barrier to the flow of liquid from the central plane 4 towards the liquid distribution device 2a, 2b, only one of the component walls 14, 15 of each composite wall 13a, 13b need be impermeable to liquid.

[0079] Each chamber 12a, 12b is subdivided by interior walls 16a, 16b (FIG. 1) in a third direction z (FIGS. 1 and 2) transverse to the first direction y and the second direction x. Each interior wall 16a, 16b is inclined relative to the walls 13a, 13b, between which the space 3 is defined. A liquid distribution space 17a, 17b is defined between the interior wall 16a, 16b and the wall 13a, 13b closest to the space 3. In one embodiment, the liquid distribution space 17a, 17b extends in the first direction y over substantially the entire extent of the wall 13a, 13b in the first direction y. In another embodiment, multiple adjacent liquid distribution spaces 17a, 17b can be provided side by side in the first direction y, with each liquid distribution space 17a, 17b extending in the second direction x from one side edge to the opposite side edge of the wall 13a, 13b.

[0080] The liquid distribution space 17 is closed at one side end and has an inlet at the opposite side end. The liquid distribution space 17 is tapered such that the height of the liquid distribution space 17 decreases towards the closed end.

[0081] At least one gap 18a-18f (FIGS. 1 and 4) exists between the free end of the inner wall 16a, 16b and the chamber side wall 19a, 19b. Both of the at least one gap 18a-18f extend along the extent of the chamber 12a, 12b in the first direction y. Each gap 18a-18f provides liquid communication between the liquid distribution space 17 defined in the chamber 12a, 12b and a diverging liquid conduit 20a, 20b. The inlet side of the diverging liquid conduit 20a, 20b is connected to the liquid inlet 10a, 10b. The outlet side is located in the gap 18a-18f. In the illustrated embodiment, flow guides 21a-21c (FIG. 3) are provided on the outlet side. The flow guides 21a-21c subdivide the diverging liquid conduit 20a, 20b into parallel passages, in this example, four passages. The side walls 22a, 22b of the diverging liquid conduit 20 are straight in the illustrated example, but may alternatively be curved.

[0082] Each of the walls 13a, 13b in which the space 3 between the liquid distribution devices 2a, 2b is located is provided with a plurality of passages 23a, 23b, 24a, 24b (Figure 2) terminating in openings for introducing liquid into the space 3.

[0083] In the illustrated embodiment, the passages 23 a , 23 b , 24 a , 24 b are oriented such that their longitudinal axes are substantially perpendicular to the central plane 4 .

[0084] In the illustrated embodiment, the further walls 15a, 15b are support walls, for example made of plastic. The further walls 15a, 15b are provided with threaded through-holes into which the nozzle devices 25a-25d (FIG. 2) are inserted. Alternatively, the nozzle devices 25a-25d can be press-fit into the through-holes. The nozzle devices 25a-25d completely block the through-holes so that liquid can only pass through the further walls 15a, 15b through the nozzle devices 25a-25d. Each section of the passages 23a, 23b, 24a, 24b is therefore defined by one of the nozzle devices 25a-25d.

[0085] The nozzle devices 25a-25d are fan nozzle devices 25a-25d that shape the liquid stream emerging from each nozzle device 25a-25d. For this purpose, the constriction forms an orifice 26 (FIG. 3) with an elongated shape having a larger dimension in the second direction x than in the first direction y. The same applies to the outlet opening 27 through which the liquid enters the space 3. This outlet opening 27 is slit-shaped in the illustrated embodiment.

[0086] Gaps 28a, 28b are defined between the walls 13a, 13b at the side edges of the walls 13a, 13b, and extend in the first direction y substantially along the extent of the walls 13a, 13b, respectively.

[0087] Thus, during use, liquid flows outward from the middle in the second direction x. The liquid distribution space 17 and diverging liquid conduit 20 ensure that liquid is introduced into the space 3 at a relatively uniform velocity, resulting in flow accelerating toward the side edges of the workpiece. As a result, a self-centering effect is achieved, maintaining the workpiece in a central plane without the need for supports that contact the workpiece. Nevertheless, the shielding structures 6a, 6b ensure that contact with the anodes 5a, 5b is prevented under all circumstances.

[0088] An example of the device 1 is configured for workpieces having a thickness of up to 100 μm, e.g., up to 60 μm, up to 50 μm, or even up to 10 μm. Typical dimensions for the height of the gaps 28a, 28b are in the range of 2-50 mm. The liquid is pumped through the gaps 28a, 28b at a velocity of at least 0.1 m / s, e.g., at least 0.5 m / s. The velocity is typically less than 10 m / s, and may be less than 5 m / s.

[0089] The shielding structures 6a, 6b are spaced apart (perpendicular to the central plane 4) by at least 5mm, at most 25mm, for example at most 20mm, or even less than 15mm. The distance from each anode 5a, 5b to the central plane 4 is at least 8mm, for example at least 10mm, and typically at most 15mm, for example at most 12mm.

[0090] In the illustrated embodiment, the nozzle devices 25a-25d are arranged in rows extending substantially parallel to the second direction x. The mutual spacing between the openings, and therefore between the nozzle devices 25a-25d, is equal within each row. In the illustrated embodiment, this spacing is also the same for all rows. However, the nozzle devices 25a-25d of each subsequent row in the first direction y are offset in the second direction x relative to the nozzle devices 25a-25d of the previous row. The offset is the same for each pair of rows, and the spacing between the rows in the first direction y is also uniform. As a result, the nozzle devices 25a-25d can be said to be arranged in columns at a slight angle α with respect to the first direction y (FIG. 3). A further consequence is that the number of nozzle devices 25a-25d can be 10 or 11. The spacing is such as to achieve a linear density of at least 16 openings 27 per meter in the second direction x. In the illustrated embodiment, the areal density is 1 / m. 2 At least 460 pieces per, say, 1 m 2 At least 600 per wall 13a, 13b. Thus, the dimension of the walls 13a, 13b in the first direction y is at most 500 mm, for example 400-450 mm. The dimension in the second direction x is at most 700 mm, for example 600-650 mm. With these dimensions, there are at least 120 openings 27 per wall 13a, 13b.

[0091] The present invention is not limited to the above-described embodiments and may be modified within the scope of the appended claims. For example, while the device in this example has a horizontal conveying plane (referred to herein as the central plane 4), similar effects can be achieved in devices with vertical conveying planes. In such devices, the flow field described herein can be achieved by submerging the device 1 relatively deeply in the bath so that liquid emerging from the top of one of the gaps 28a, 28b does not spray into free space. In embodiments with a vertical conveying plane, the dimension in the first direction x may be larger, for example, up to 1300 mm. The minimum number of nozzle devices 25a-25d per unit area and the minimum linear density in the second direction x may be approximately half the values ​​given above for embodiments with a horizontal conveying plane, without sacrificing the effect of relatively well retaining the workpiece within the central plane.

[0092] In an arrangement comprising several devices 1 arranged in series, the spacing between the shielding structures 6a, 6b may decrease in the first direction y.

[0093] The liquid-accessible space does not need to be completely empty, as long as the liquid can flow through it. Therefore, sections of the space can be filled with a porous structure, such as a foam, which can act as a spacer, for example, between the walls 13 a, 13 b and the anodes 5 a, 5 b and / or between the anodes 5 a, 5 b and the shielding structures 6 a, 6 b. [Explanation of symbols]

[0094] 1 device 2a, 2b Liquid distribution device 3 space 4 Center plane 5a, 5b Anode 6a,6b Shielding structure 7. Transport Devices 8 Clamp 9 Drive unit 10a,10b Liquid inlet 11a,11b Liquid supply conduit 12a, 12b Chambers 13a, 13b First compound wall and second compound wall 14a, 14b Housing wall 15a, 15b Further walls 16a,16b Inner wall 17a,17b Liquid distribution space 18a~18f Gaps in the chamber 19a, 19b Chamber side wall 20a, 20b Expanding liquid conduit 21a~21c Flow Guide 22a, 22b Expanding conduit side wall 23a, 23b First Passage 24a, 24b Second Passage 25a~25b Nozzle Device 26 Orifice 27 Exit opening 28a,28b gap

Claims

1. 1. A device for a cell of an apparatus for wet processing flat workpieces, comprising: a structure including a first wall and a second wall; the workpiece is movable in a first direction within a central plane through a space between the first wall and the second wall; openings for introducing pressurized liquid between the first wall and the second wall are provided on opposite sides of the central plane and facing the central plane; the openings are distributed in the first direction and in a second direction transverse to the first direction; discharge openings for the liquid to exit the space are defined along the extent of the space in the first direction and on opposite sides of the space as viewed in the second direction; the first wall and the second wall form a barrier to the flow of liquid from the space in a direction perpendicular to the central plane; passages extending through the first wall and the second wall, each passage arranged to direct the liquid to a respective one of the openings; at least one liquid distribution space extending in the second direction across the passage inlet is defined on an opposite side of at least one of the first wall and the second wall to the space; The liquid distribution space is defined by a barrier that is inclined relative to the first wall or the second wall such that the liquid distribution space tapers toward an edge of the first wall or the second wall. A device characterized in that

2. 2. The device of claim 1, comprising at least one diverging liquid conduit having an inlet on one side connectable to a liquid supply conduit and diverging toward opposite sides that are in liquid communication with the liquid distribution space at multiple points along the width of the diverging liquid conduit.

3. 3. The device of claim 2, wherein the diverging liquid conduit comprises a flow guide on an outlet side of the diverging liquid conduit to subdivide the diverging liquid conduit into parallel passages.

4. The device of claim 2 , wherein the expanding liquid conduit and the liquid distribution space are defined within a chamber within a housing of one of the first and second liquid distribution devices by the barrier extending into the chamber.

5. The device of claim 1 , wherein at least one of the discharge openings has a height of at most 100 mm.

6. The device of claim 5 , wherein the height is at most 50 mm.

7. The device of claim 6 , wherein the height is less than 40 mm.

8. The device of claim 1 , wherein the first wall and the second wall comprise component walls made of different materials.

9. 9. The device of claim 8, wherein at least one component wall is made from an electrically insulating material and at least one other component wall is made from a mechanically stronger material.

10. The device of claim 1 , wherein at least one of the first wall and the second wall is provided with a threaded through-hole, and a nozzle device is inserted into the through-hole.

11. The device of claim 10 , wherein the nozzle device completely blocks the through-hole to prevent bypass of liquid through the first wall and the second wall.

12. The device of claim 1 , further comprising at least one porous structure filling at least a portion of said space.

13. The device of claim 12 , wherein the porous structure comprises a foam that acts as a spacer.

14. The device of claim 1 , wherein the device is configured to provide a self-centering effect that maintains the workpiece within the central plane without a support contacting the workpiece.

15. The device of claim 1 , wherein the device is configured to process workpieces having a thickness of up to 100 μm.

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