TWI643355B - Free-standing metallic article for semiconductors - Google Patents

Abstract

A self-standing metal article and a method of manufacturing the same are disclosed, wherein the metal object is electroformed on a conductive mold core. The mold core has an outer surface having a preformed pattern, wherein at least a portion of the metal object is formed in the preformed pattern. The metal object is separated from the conductive mold core to form a self-standing metal object that can be coupled to a surface of a semiconductor material for a photovoltaic cell.

Description

Self-standing metal objects for semiconductors (1) Related application

The present application claims priority to U.S. Patent Application Serial No. 13/798,123, filed on Mar. 13, 2013, entitled <RTI ID=0.0> This article is incorporated herein by reference. This application is also related to the following applications: 1) U.S. Patent Application Serial No. 13/798,124, filed on March 13, 2013, to B. U.S. Provisional Patent Application No. 61/778,443, filed on March 13, 2013 by Babayan et al.; and 3) entitled "Self-standing metal for semiconductors" And U.S. Provisional Patent Application Serial No. 61/778, 444, filed on Jan. 13, 2013, the entire disclosure of which is incorporated herein by reference.

Field of invention

This invention relates to self-standing metal articles for semiconductors.

A solar cell is a device that converts photons into electrical energy. The electrical energy generated by the battery is collected through electrical contacts coupled to the semiconductor material, and The routing is interconnected with other photovoltaic cells in the module. The "standard battery" model of a solar cell has a semiconductor material that absorbs and converts it into electrical energy, which is placed under the anti-reflective coating (ARC) layer and above the metal backing. Electrical contacts are typically fabricated to a semiconductor surface using a fire-through paste that is heated to diffuse the paste through the ARC layer and to contact the metal paste on the surface of the cell. The paste is substantially patterned into a set of fingers and bus bars that are subsequently soldered to other cells using strips to create a module. Another type of solar cell has a semiconductor material sandwiched between transparent conductive oxide layers (TCOs) which is subsequently coated with a final conductive paste layer that is also combined into a finger/bus bar pattern.

In both types of batteries, a metal paste of silver is typically used to cause current to flow in a horizontal direction (parallel to the surface of the cell), thereby allowing the connection between the solar cells to be fabricated to create a module. Solar cell metallization is most commonly accomplished by printing a silver paste onto a cell, curing the paste, and subsequently soldering the strip across the screen printed bus bars. However, silver is expensive relative to other components of solar cells and accounts for a high percentage of total cost.

Alternative methods for metallizing solar cells are known in the industry to reduce silver costs. For example, attempts have been made to replace copper with copper by directly plating copper onto a solar cell. However, copper plating has the disadvantage that the battery is contaminated with copper, which can affect reliability. When directly plating onto the surface of the battery, the plating throughput and yield are also problematic due to the numerous steps required for electroplating, such as depositing a seed layer, applying a mask, and etching or laser etching the plating area to form The pattern you need. Other methods for forming electrical conduits on solar cells include encapsulating conductive lines with parallel wires or polymeric sheets and etc. Lay to the configuration on the battery. However, the use of wire mesh brings problems such as undesired manufacturing costs and high series resistance.

The present invention discloses a self-standing metal object and a manufacturing method in which a metal object is electroformed on a conductive mold core. The mold core has a preformed pattern outer surface, wherein at least a portion of the metal object is formed in the preform pattern. The metal object is separated from the conductive mold core to form a self-standing metal object that can be coupled to the surface of the semiconductor material used for the photovoltaic cell.

100, 160, 801, 930, 1160‧‧‧ solar cells

110‧‧‧Anti-reflective coating layer/ARC layer

120‧‧‧ emitter/doped area

125,835,837‧‧‧Doped areas

130‧‧‧base (region)

140‧‧‧Front Contact/Electrical Contact

145‧‧ ‧ bus bar

150‧‧‧After contact layer/electrical contact

170‧‧‧Non-conducting layer/passivation layer

175, 845, 2070‧ ‧ holes

200, 400, 500, 1100, 1220, 1700, 1800 ‧ ‧

205‧‧‧ (outside) surface

210‧‧‧Pattern Components/Preformed Patterns

212‧‧‧pattern elements/patterns

300, 650, 655, 810, 850, 860, 1150, 1920, 2220‧ ‧ metal objects

310, 312, 812, 925, 1025, 1111, 1210, 1212, 1310‧‧‧ electroforming components

315‧‧‧ Nickel layer

320‧‧‧Intersecting components

410, 510, 530, 540‧‧‧ pattern elements

420‧‧‧metal base

430‧‧‧ dielectric layer

505, 1720‧‧‧ outer surface

520, 1225‧‧‧ release layer

600a, 600b‧‧‧ metal layer

610, 620, 852, 862‧‧ ‧ fingers

612, 622‧‧‧ bottom surface

630, 814, 854, 864‧‧‧ frame components

660‧‧‧Interconnect components

670‧‧‧First grid area/grid/first area

680‧‧‧Second Area/Interconnect Components

690‧‧‧Electric conduit/grid

700, 1400, 1600‧‧‧ flow chart

710~770, 1410~1490‧‧‧ steps

800, 1300 ‧ ‧ photovoltaic battery

820‧‧‧ Attachment materials

830‧‧‧Photovoltaic components

831‧‧‧ transparent layer

832‧‧‧light incident layer

833, 2210‧‧‧ semiconductor substrate

834‧‧‧Action area

836‧‧‧After contact layer

840‧‧‧ Passivation layer

910‧‧‧ solder joints

920‧‧‧Metal components/electroforming components

927‧‧‧Chamfer corner

1010‧‧‧Solder (contact)

Section 1020‧‧‧

1027‧‧‧Characteristics

1112‧‧‧Over plating

1120‧‧‧metal base

1130‧‧‧Electroforming components/dielectric layers

1140‧‧‧ arrow

1170‧‧‧Semiconductor assembly

1180‧‧‧encapsulating agent

1190‧‧‧ window layer

1212‧‧ (round) head

1230‧‧‧ polymer tablets

1234‧‧‧Adhesive layer

1315‧‧‧ polymer layer

1330‧‧‧Polymer sheet/polymer material/ polymer

1370‧‧‧Semiconductor components/batteries

1510‧‧‧Semiconductor device

1520‧‧‧ Conductive metal layer / conductive layer

1530‧‧‧Grid

1540‧‧‧ shaded area

1545‧‧‧Exposed part

1550‧‧‧nitriding layer

1710‧‧‧Preformed pattern

1810‧‧‧First preformed pattern

1820‧‧‧ top surface

1850‧‧‧Second preformed pattern

1860‧‧‧ bottom surface

1900, 2000, 2100‧‧‧ modules

1910, 1910a~1910e, 2200‧‧‧ batteries

1930‧‧‧Substrate

1941~1943, 2041~2043, 2141~2143, 2145‧‧‧ fold line

1950, 2050, 2151‧‧ Interconnection

1960‧‧‧ openings

2240‧‧‧dotted/tangent

The various aspects and embodiments of the invention described herein can be used alone or in combination with one another. The aspects and embodiments will now be described with reference to the following drawings.

1A is a perspective view of a conventional solar cell.

1B is a cross-sectional view of a conventional back contact solar cell.

Figure 2 shows a perspective view of an exemplary electroformed mold core in an embodiment.

3A-3C depict cross-sectional views of an exemplary stage in the manufacture of a self-standing electroformed metal article.

Figure 4 provides a cross-sectional view of one embodiment of a conductive mold core.

Figure 5 provides a cross-sectional view of another embodiment of a conductive mold core.

6A-6B are top views of two embodiments of metal objects.

Figure 6C is a cross-sectional view of section B-B of Figure 6B.

6D-6E are portions of still other embodiments of the cross section of Fig. 6B Divided into cross-sectional views.

6F-6G are top views of still other embodiments of metal objects.

Figure 7 is an illustrative flow diagram of a process for making an electroformed article and forming a semiconductor device such as a solar cell.

8A-8B are perspective views of an exemplary solar cell fabricated with a self standing metal object.

Figure 8C is a cross-sectional view of another embodiment of a solar cell.

Figure 8D is a top plan view of an exemplary metal object for use in the solar cell of Figure 8C.

9A-9B illustrate an embodiment of a custom topography of an electroformed component.

10A-10B illustrate another embodiment of a custom topography of an electroformed component.

11A-11C are cross-sectional views showing stages in which a metal article having a dielectric transfer layer is formed in an embodiment.

Figure 12 depicts a cross-sectional view of one embodiment of the removal of a metal article using a polymer sheet.

13A-13B are cross-sectional views of an exemplary polymer layer fabricated into a back contact solar cell.

Figure 14 shows an illustrative flow diagram for fabricating a polymer layer having an electroformed article and forming a semiconductor device such as a solar cell.

Figures 15A-15D provide the use of metal objects as masks to make semi-guides A perspective view of an exemplary stage of patterning of a conductive layer on a bulk material.

16 is an illustrative flow diagram of a method of using a metal object as a mask to pattern a conductive layer on a semiconductor material.

Figure 17 is a cross-sectional view of an exemplary cylindrical mold core.

Figure 18 shows a cross-sectional view of one embodiment of a flat mold core having a pattern on its top and bottom surfaces.

Figure 19 shows a top view of one embodiment of a flexible module having fold lines.

Figure 20 shows a top view of another embodiment of a flexible module.

Figure 21 provides a top view of yet another embodiment of a flexible module having bi-directional folding capabilities.

Figure 22 is a top plan view of a flexible solar cell using a metal article as described herein.

1A is a simplified schematic diagram of a conventional solar cell 100 including an anti-reflective coating (ARC) layer 110, an emitter 120, a base 130, a front contact 140, and a back contact layer 150. The emitter 120 and the base 130 are doped as a semiconductor material of a p+ or n-region, and may be collectively referred to as an active region of a solar cell. The front contact portion 140 typically burns through the anti-reflective coating layer 110 to form an electrical contact in the active area. The incident light enters the solar cell 100 via the ARC layer 110, resulting in a photocurrent at the junction of the emitter 120 and the base 130. It can be seen that the shadowing caused by the front contact portion 140 will affect the efficiency of the battery 100. The generated current is collected via a circuit connected to one of the front contact portion 140 and the back contact layer 150. The bus bar 145 can be connected here as a finger The front contact portion 140 of the component. The bus bar 145 collects current from the front contact 140 and can also be used to provide interconnection between other solar cells. The assembly of the front contact portion 140 and the bus bar 145 may also be referred to as a metallization layer. In other types of solar cells, a transparent conductive oxide (TCO) layer can be used instead of a dielectric ARC layer to concentrate the current. In a TCO type battery, a metallization in the form of, for example, front contact 140 and bus bar 145 can be fabricated onto the TCO layer without burning through to collect current from the TCO solar cell.

FIG. 1B illustrates a simplified schematic diagram of another type of solar cell 160 in which electrical contacts are formed on the back side opposite the entrance of light. The solar cell 160, also referred to as a finger-shaped back contact cell, includes an ARC layer 110, a base region 130 made of a semiconductor substrate, and doped regions 120 and 125 having opposite polarities (eg, p-type and n-type). . The doped regions 120 and 125 are on the back side of the cell 160 opposite the ARC layer 110. The non-conductive layer 170 provides separation between the doped regions 120 and 125 and also completes the passivation of the back surface of the cell 160. Electrical contacts 140 and 150 are forked with one another and individually form electrical connections to doped regions 120 and 125 via apertures 175 in passivation layer 170. Although the electrical contacts 140 and 150 do not cause a shadowing problem in such a back contact type solar cell, they may still cause other problems such as loss of manufacturing yield when the contact portion is formed on the battery, and silver is used. High material cost at the time of contact or battery decay when copper is used for contact.

Metallization of solar cells typically involves screen printing silver paste in a desired pattern of electrical contacts to be connected to the battery. In FIG. 1A, front contact portions 140 are grouped into a linear pattern of parallel segments. Because the cost of silver can be enormous Increasing the cost of solar cells, it is extremely desirable to reduce or even eliminate the use of silver. Copper is a remarkable silver substitute because of its high electrical conductivity, but copper can cause semiconductor contamination and thus reduce the performance of solar cells. A known method of using copper in a solar cell involves directly depositing copper on the battery. However, such methods require solar cells to suffer from temperature and chemicals associated with many steps during such plating procedures, which can result in damage to the battery. In other known methods, the configuration of the woven mesh of parallel copper wires or wires is fabricated separately from the battery and subsequently bonded to the battery. However, it is difficult to align the wire with the battery by such methods, or to create a wire that is small enough to minimize the shadow on the solar cell. Wire squares encapsulated within the polymeric film are also fabricated, but such methods can be complex and still suffer from shadowing and alignment problems, particularly due to the presence of polymeric sheets. Copper paste is another alternative, but these pastes are difficult to apply and there is still the problem of diffusion into the solar cell.

In the present disclosure, an electrical conduit for a semiconductor such as a photovoltaic cell is fabricated into an electroformed self-standing metal article. These metal objects are fabricated separately from the solar cells and may include multiple components, such as fingers and bus bars, that can be stably transferred as a single piece of workpiece and easily aligned with the semiconductor device. In the electroforming process, the components of the metal object are integrally formed with each other. The metal article is fabricated in an electroformed mandrel that produces a patterned metal layer tailored to a solar cell or other semiconductor device. For example, the metal object can have gridlines that have a high aspect to width aspect ratio that minimizes shadowing of the solar cell. Metal objects can replace traditional bus bars for battery metallization, inter-cell interconnection and module manufacturing Attributes and strips are wired. The ability to fabricate metallization layers for photovoltaic cells as a separate component that can be stably transferred between processing steps provides a number of advantages in material cost and manufacturing.

2 depicts a perspective view of a portion of an exemplary electroformed mold core 200 in an embodiment. The mold core 200 may be made of a conductive material such as stainless steel, copper, anodized aluminum, titanium or molybdenum, nickel, nickel-iron alloy (eg, Invar), copper, or any combination of such metals, and may be designed to have Sufficient area to allow high plating current and high throughput. The mold core 200 has an outer surface 205 having a preformed pattern that includes pattern elements 210 and 212 and that can be tailored to the desired shape of the electrical conduit element to be produced. In this embodiment, pattern elements 210 and 212 are grooves or grooves having a rectangular cross-section, although in other embodiments, pattern elements 210 and 212 can have other cross-sectional shapes. The pattern elements 210 and 212 are depicted as forming intersecting sections of a grid pattern, wherein in this embodiment, the sets of parallel lines intersect each other perpendicularly.

The pattern element 210 has a height "H" and a width "W", wherein the high aspect ratio defines an aspect ratio. By using pattern elements 210 and 212 in the mold core 200 to form a metal object, the electroformed metal part can be customized for photovoltaic applications. For example, the aspect ratio can be between about 0.01 and about 10. In some embodiments, the aspect ratio can be designed to be greater than 1, such as between about 1 and about 10, or between about 1 and about 5. Having a height greater than the width allows the metal layer to carry sufficient current, but compared to, for example, a standard circular line having an aspect ratio of 1, or a conventional screen printing pattern having a horizontal flatness and having an aspect ratio of less than 1, on the battery The shading is reduced. The masking value of the screen printed metal fingers can be, for example, more than 6%. By having a custom aspect as described herein A masking value of less than 6% can be achieved, such as between 4 and 6%, compared to metal objects. Thus, the ability to fabricate electrical conduits having an aspect ratio greater than one allows photovoltaic cells to have minimal pore loss, which is important to maximize efficiency. In embodiments where an electroformed electrical conduit is used on the back surface of a solar cell, an aspect ratio such as other values less than one may be used.

The aspect ratio of the pattern elements, as well as the cross-sectional shape and longitudinal layout, can be electroformed to meet desired specifications such as current capacity, series resistance, shadow loss, and battery layout. Any electroforming program can be used. For example, the metal object can be formed by a plating process. In particular, since electroplating is generally an isotropic procedure, limiting the plating with a patterned mold core to customize the shape of the part is an important improvement for maximizing efficiency. In addition, although the high and narrow conduit lines are typically unstable when placed on a semiconductor surface, custom patterns that can be fabricated using the mold core allow for topography such as interconnect lines to be high The narrow conduit provides stability. In some embodiments, for example, the preformed pattern can be assembled into a continuous grid with intersecting lines. This configuration not only provides mechanical stability to multiple electroformed components forming a grid, but also allows for a low series resistance due to current distribution across more conduits. The grid structure also improves the robustness of the battery. For example, if portions of the grid are damaged or inoperative, current can flow around the damaged area due to the presence of the grid pattern.

3A-3C are simplified cross-sectional views of an exemplary stage in the fabrication of a metal layer workpiece using a mold core. In Fig. 3A, a mold core 200 having a pattern element 210 is provided. The mold core 200 is subjected to an electroforming process in which an electroformed component 310 is formed in the pattern element 210 as shown in FIG. 3B. Embodiments in Figures 3A to 3C The pattern elements 210 have been designed to have an aspect ratio that is greater than their respective values in FIG. Electroformed component 310 can be, for example, pure copper, or in other embodiments an alloy of copper. In other embodiments, a layer of nickel may be first plated onto the mold core 200, followed by electroplating of copper such that the nickel provides a barrier to the processing of the semiconductor device from copper contamination. An additional layer of nickel may optionally be plated on top of the electroformed component 310 to encapsulate the copper, as depicted by the nickel layer 315 in Figure 3B. In other embodiments, a plurality of layers may be plated into the pattern element 210 using various metals as desired to achieve the desired properties of the fabricated metal article.

In FIG. 3B, electroformed component 310 is shown as being formed flush with outer surface 205 of mold core 200. Electroformed component 312 shows another embodiment of an overplatable component. In the case of electroformed component 312, the plating process continues until the metal extends beyond surface 205 of mold core 200. Typically, a rounded top overplated portion will be formed due to the isotropic nature of the electroforming, which can serve as a handle to facilitate extraction of the electroformed component 312 from the mold core 200. The rounded top of electroformed component 312 can also provide optical advantages in photovoltaic cells, such as becoming a refractive surface to aid light collection. In another embodiment not shown, in addition to being formed within the preformed pattern 210, the metal article can have portions formed on top of the surface 205, such as bus bars.

In FIG. 3C, electroformed component 310 is removed from mold core 200 into a self-standing metal article 300. Electroformed component 310 can include intersecting component 320, such as formed by pattern element 212 of FIG. The intersecting elements 320 can assist in forming the metal article 300 into a single piece of self-standing workpiece that can be easily transferred to other processing steps while maintaining the individual components 310 and 320 aligned with one another. Other processing steps may include a coating step for self-standing metal object 300 and The assembly step incorporated into the semiconductor device. By forming the metal layer of the semiconductor into a self-standing workpiece, the manufacturing yield of the entire semiconductor assembly will not be affected by the yield of the metal layer. In addition, the metal layer can withstand temperature and process separately from other semiconductor layers. For example, the metal layer can undergo a high temperature process or chemical bath that will not affect the remainder of the semiconductor assembly.

After the metal article 300 is removed from the mold core 200 in Figure 3C, the mold core 200 can be reused to make other components. Since the mold core 200 can be reused, a significant cost reduction is provided compared to the prior art that directly performs electroplating on solar cells. In the direct plating method, a mask or a mold core is formed on the battery itself, and thus must be built on each battery and often broken. Having a reusable mold core reduces processing steps and saves cost compared to techniques that require patterning and subsequent plating of semiconductor devices. In other conventional methods, a thin printed seed layer is applied to the surface of the semiconductor to initiate the plating process. However, the method of seed layer can result in low throughput. In contrast, the reusable mold core method as described herein can utilize a thick metal mold core that allows for high current capacity, thereby resulting in high plating current and thus high throughput. The metal mold core thickness can be, for example, between 0.2 and 5 mm.

4 through 5 are cross-sectional views of exemplary mold cores showing various embodiments of the mold core and pattern design. In FIG. 4, a flat metal core base 420 has a dielectric layer 430 laid thereon. A pattern including pattern elements 410 for forming metal objects is generated in this dielectric layer 430. Dielectric layer 430 can be, for example, a fluoropolymer (eg, Teflon®), patterned photoresist (eg, Dupont Riston® thick film photoresist), or a thick layer of epoxy based photoresist (eg, SU-8). The photoresist is exposed and removed as appropriate to reveal the desired image case. In other embodiments, the dielectric layer 430 can be patterned by, for example, machining or precision laser cutting. In such a mold core 400 having a pattern element surrounded by a dielectric material, electroplating will begin to fill the trenches of the pattern element 410 from the bottom up at the metal mold base 420. The use of a dielectric material or permanent photoresist allows reuse of the mold core 400, which reduces the number of process steps, consumable costs, and throughput of the overall process compared to the consumable mold core.

Figure 5 shows another mold core 500 made primarily of metal, which includes holes for forming a metal object. When electroforming is performed using the metal mold core 500, the metal surface of the pattern member 510 is allowed to be quickly plated from all three sides of the groove pattern. In some embodiments of the mold core 500, a release layer 520, such as a dielectric material or a low adhesion material (e.g., fluoropolymer), may optionally be applied to various regions of the mold core 500. This release layer 520 can reduce the adhesion of the electroformed component to the mold core 500, or can minimize the adhesion of a substrate such as a viscous film that can be peeled off from the electroformed article. The release layer 520 can be patterned simultaneously with the metal mold core or patterned in a separate step, such as by wet or dry etching through a photoresist. The pattern elements 510, 530, and 540 in the metal mold core can be, for example, grooves and intersecting grooves, and can be formed by, for example, machining, laser cutting, lithography, or electroforming. In other embodiments, the mold core 500 may not require the release layer 520 if the surface of the mold core exposed to the plating solution is selected to have poor adhesion to the metal object. For example, for an electroformed component that will have a first nickel plating layer (ie, an outer layer), the mold core 400 can be made of copper. Copper has a low viscosity to nickel and thus allows the formed nickel coated workpiece to be easily removed from the copper mold core. When the release layer 520 is applied to the mold core 500, the relative depth of the trench pattern member 510 in the metal and the thickness of the dielectric coating can be The selection is made to minimize void formation of the metal workpiece formed in the pattern element 510 while still having a high plating rate.

FIG. 5 shows another embodiment in which the release layer 520 has partially extended into the depth of the pattern element 530. Such a coating extending into the pattern element 530 can permit electroforming between the pattern element 410 surrounded by the dielectric material of FIG. 4 and the metal pattern element 510 of FIG. The amount of release layer 520 that extends into pattern element 530 can be selected to achieve the desired electroforming rate. In some embodiments, the release layer 520 can extend into the pattern element 530, for example, by about one-half the amount of pattern width. The pattern element 530 having the release layer 520 extending into the trench can allow for a more uniform plating rate within the trench, and thus a more uniform grid can be fabricated. The amount by which the dielectric or release layer 520 extends into the trench can be modified to optimize overall plating rate and plating uniformity.

Figure 5 shows yet another embodiment of a mold core 500 in which the pattern element 540 has a tapered wall. The tapered wall is wider at the outer surface 505 of the mold core 500 to facilitate removal of the formed metal component from the patterned mold core. In other embodiments not shown, the cross-sectional shape of the preformed pattern for any of the mold cores described herein can include, for example, but not limited to, a curved cross-section, a beveled edge at the corner of the cross-section of the pattern, along the pattern A curved path of length and a section that intersect each other at various angles.

6A and 6B illustrate top views of exemplary metal layers 600a and 600b that may be fabricated from the electroformed mold cores described herein. Metal layers 600a and 600b include electroformed elements embodied herein as substantially parallel fingers 610 that have been formed by substantially parallel grooves in the conductive mold core. Metal layer 600b also includes levels that are embodied herein as intersecting vertical fingers 610 An electroformed component of finger 620, wherein fingers 610 and 620 intersect at approximately a right angle. In other embodiments, the fingers 610 and 620 can intersect at other angles while still forming a continuous grid or mesh pattern. The metal layers 600a and 600b also include a frame member 630 that can be used as a bus bar to collect current from the fingers 610 and 620. A bus bar having a portion integrally formed as a metal object can provide process improvement. In the present high-capacity solar module manufacturing method, the battery connection is often achieved by manually soldering the metal strip to the battery. This practice typically results in battery rupture or damage due to manual handling and stress applied to the battery by the solder strip. In addition, manual welding methods result in high labor-related production costs. Thus, as with the possible solution of electroformed metal articles as described herein, bus bars or strips previously formed and attached to the metallization layer can have a low cost automated manufacturing process.

The frame member 630 can also provide mechanical stability such that the metal layers 600a and 600b are a single self-standing workpiece when removed from the mold core. That is, the metal layers 600a and 600b are a single component because the fingers 610 and 620 remain connected when they are self-made from photovoltaic cells or other semiconductor components. Frame element 630 may further assist in maintaining spacing and alignment between finger elements 610 and 620 when the finger elements are attached to a photovoltaic cell. Frame member 630 is shown extending across one of the edges of metal layers 600a and 600b in Figures 6A-6B. However, in other embodiments, the frame members may extend only partially across one edge, or may be bordered by more than one edge, or may be assembled into one or more ears on the edge, or may exist in the mesh itself Inside. In addition, the frame members can be electroformed simultaneously with the fingers 610 and 620, or in other embodiments after the fingers 610 and 620 have been formed. Electroforming in separate steps.

Figure 6C shows a cross section of the metal layer 600b taken at section B-B of Figure 6B. The fingers 610 in this embodiment are shown to have an aspect ratio greater than one, such as from about 1 to about 5, and an aspect ratio such as about 2 in this figure. The wider cross-sectional height can reduce the shadowing effect of the metal layer 600b on a photovoltaic cell. In various embodiments, only a portion of the fingers 610 and 620 can have an aspect ratio greater than one, or that most of the fingers 610 and 620 can have an aspect ratio greater than one, or that all of the fingers 610 and 620 can have An aspect ratio greater than one. The height "H" of the fingers 610 can range, for example, from about 5 microns to about 200 microns, or from about 10 microns to about 300 microns. The width "W" of the fingers 610 can range, for example, from about 10 microns to about 5 mm, such as from about 10 microns to about 150 microns. The distance between the parallel fingers 610 has a distance "P" between the lines among the fingers. In some embodiments, the spacing can range, for example, between about 1 mm and about 25 mm. In Figures 6B and 6C, fingers 610 and 620 have different widths and spacings, but are substantially equal in height. In other embodiments, the fingers 610 and 620 can have different widths, heights, and spacings from one another, or can have some of the same characteristics, or can have all of the same characteristics. These values can be selected based on factors such as the size of the photovoltaic cell, the amount of shielding used for the desired efficiency, or the coupling of metal objects to the front or rear of the cell. In some embodiments, the fingers 610 can have a spacing of between about 1.5 mm and about 6 mm, and the fingers 620 can have a spacing of between about 1.5 mm and about 25 mm. Fingers 610 and 620 are formed in a mold core having a shape and spacing substantially the same as the grooves of fingers 610 and 620. Frame member 630 can have the same dimensions as fingers 610 and 620 The height may be a thinner workpiece as indicated by the dashed line in Fig. 6C. In other embodiments, frame member 630 can be formed over finger elements 610 and 620.

Figure 6C also shows that the fingers 610 and 620 can be substantially coplanar with each other because the fingers 610 and 620 have a plurality of cross-sectional areas that overlap each other. The coplanar grid as depicted in Figure 6C can provide a profile that is lower than the overlapping circular lines of the same cross-sectional area, as compared to conventional grids that are woven up and down each other. The intersecting coplanar lines of metal layer 600b are also integrally formed with each other during the electroforming process, thereby providing greater robustness to the self-standing articles of metal layer 600b. That is, the unitary elements are formed as a workpiece rather than being joined together by separate components. Figures 6D and 6E show other embodiments of coplanar intersecting elements. In FIG. 6D, the fingers 610 are shorter in height than the fingers 620, but are disposed within the cross-sectional height of the fingers 620. Fingers 610 and 620 have bottom surfaces 612 and 622, respectively, which are aligned in this embodiment, such as to provide a flat surface for mounting to a semiconductor surface. In the embodiment of FIG. 6E, the fingers 610 have a greater height than the fingers 620 and extend beyond the top surface of the fingers 620. The majority of the cross-sectional area of the fingers 610 overlaps the entire cross-section of the fingers 620, and thus the fingers 610 and 620 are coplanar as defined herein.

Figures 6F and 6G show other embodiments in which an electroformed metal object interconnects photovoltaic cells in a module. A typical module has a number of batteries connected in series, such as between 36 and 60. These connections are made by attaching the front of a battery to the back of the next cell using a copper strip coated with solder. Attaching the strap in this manner requires a thin and therefore resistive strip so that the strip can bend around the cell without damaging the battery edge. This mutual The connecting pieces typically also require three separate strips that are separately welded. In the embodiment of FIG. 6F, metal object 650 has interconnecting elements 660 that have been integrally molded with first grid region 670. Interconnect element 660 has a first end coupled to one of grids 670 and is configured to extend beyond the surface of the photovoltaic cell to allow connection to an adjacent cell. Interconnect element 660 replaces the need to solder separate strips between cells, thereby reducing manufacturing costs and enabling viable automation. In the illustrated embodiment, interconnect element 660 is a straight section, although other configurations are possible. Also, the number of interconnect elements 660 can vary as desired, such as providing multiple elements 660 to reduce electrical resistance. The interconnect element 660 can be bent or angled after electroforming to enable connection between the front and back of the battery, or can be fabricated in the mold core to be angled relative to the grid 670.

The opposite ends of the interconnecting member 660 can be coupled to a second region 680, wherein the second region 680 can also be electroformed as part of the metal object 650 in the conductive mold core. In FIG. 6F, the second zone 680 is assembled into an ear piece, such as a bus bar, which can then be electrically connected to one of the adjacent battery electrical conduits 690. The conduit 690 is here assembled into a grid, but other configurations are possible. Grid 670 can be used, for example, as an electrical conduit on the front surface of a first battery, while grid 690 can be an electrical conduit on the surface behind a second battery. In the embodiment of Figure 6G, the metal object 655 has a mesh instead of a bus bar type connection. The metal article 655 includes a first region 670, an interconnecting member 660, and a second region 680, all of which have been electroformed into a single component such that the inter-cell connection has been provided by the metal article 655. Thus, metal objects 650 and 655 not only provide electrical conduits on the surface of a photovoltaic cell, but also provide interconnection between cells.

Although the mold core described in Figures 2 to 5 has been described as a flat mold core, However, the mold core can be otherwise cylindrical to facilitate a continuous process. 17 shows a cross-sectional view of an exemplary cylindrical mold core 1700 having a preformed pattern 1710 formed on an outer surface 1720. In such an embodiment, the cylindrical mold core 1700 can be impregnated and rotated in an electroforming bath, and the resulting single piece of metal article can be formed into a continuous strip that can then be trimmed as a separate piece as desired. . In other embodiments, the flat core 1800 illustrated in the cross-sectional view of FIG. 18 can have a first preformed pattern 1810 in the top surface 1820 and a second preformed pattern 1850 in the bottom surface 1860. The first and second preform patterns 1810 and 1850 can be the same or different from one another. For example, in FIG. 18, the first preformed pattern 1810 has elements having different widths, heights, and spacings than the second electroformed pattern 1850. The double side core 1800 can be used to make two patterns at a time, or in other embodiments, one side can be shielded while the other side is used to make an electroformed part. In one embodiment, the first preformed pattern can be used to fabricate a metal object for the front side of the solar cell, and the second preformed pattern can be used to form a metal object for the back side of the solar cell.

FIG. 7 depicts an illustrative flow diagram 700 for a self-standing electroformed metal article for fabricating a semiconductor assembly such as a photovoltaic cell. In the present disclosure, references to semiconductor materials forming semiconductor devices or photovoltaic cells may include amorphous germanium, crystalline germanium, or any other semiconductor material suitable for use in photovoltaic cells. In step 710, an electroforming process is performed using a conductive mold core. The mold core has one or more preformed patterns in which metal objects are formed. In some embodiments, the metal objects are assembled for use as an electrical conduit within a photovoltaic cell. In some embodiments, the metal object can include a topography that enables connection between photovoltaic cells of the solar module. Preform The case may have an aspect ratio greater than one and may include a plurality of parallel patterns that intersect each other. At least a portion of the machined electroformed metal article is built into the preformed pattern. Other portions of the metal article, such as a bus bar, are formed in or on the top surface of the preform.

Electroforming step 710 can include contacting the outer surface of the mold core with a solution comprising a salt of a first metal, wherein the first metal can be, for example, copper or nickel. This first metal may form the entire metal object or may form a metal precursor of one of the other metal layers. For example, a salt solution containing a second metal can be plated onto the first metal. In some embodiments, the first metal can be nickel and the second metal can be copper, wherein the nickel provides a barrier to copper diffusion. A third metal may optionally be plated onto the second metal, such as a third metal that is nickel plated onto a second metal that is copper, the second metal having been plated onto the first metal that is nickel. In this three-layer structure, the copper conduit is encapsulated by nickel to provide a barrier that prevents copper contamination from entering the semiconductor device. The electroforming program parameters in step 710 can be, for example, a current between 1 and 3000 amps per square foot (ASF) and a plating time between, for example, 1 minute to 200 minutes. Other conductive metals may be applied to improve adhesion, improve wettability, act as a diffusion barrier, or improve electrical contact, such as tin, tin alloy, indium, indium alloy, niobium alloy, nickel tungstate or cobalt tungstate .

After forming the metal object, the metal object separates from the conductive mold core into a self-standing single piece workpiece in step 720. This separation step may involve lifting or peeling the article from the mold core with or without the use of a temporary polymeric sheet, or with or without a vacuum treatment. In other embodiments, the removing step can include thermal or mechanical shock or ultrasonic energy to assist in the release of the mold core. Pieces. The ready-to-stand metal object is then formed into the photovoltaic cell or other semiconductor device through attachment and electrical coupling objects as described below. Transferring the metal article to each manufacturing step can be performed without the need for supporting elements such as plastic or polymeric substrates, thereby reducing cost.

Self-standing metal objects can be mounted directly to the solar cell or can be subjected to other processing steps prior to attachment. It is noted that for the purposes of the present invention, "metal objects" are also used interchangeably and are also referred to as grids or meshes, even though some embodiments may not include intersecting cross members. If a metal object that does not have a barrier layer has been formed, the separated self-standing metal object can optionally be subjected to an additional plating operation in step 730. For example, nickel plating can be performed by, for example, no electricity or plating. In some embodiments, the metal object may also be plated with nickel-cobalt-tungsten or cobalt-tungsten-phosphorus at high temperatures to create a diffusion barrier for the copper material, while standard nickel plating prevents migration of copper in the battery below 300 °C. .

After any other plating procedures have been completed, in step 740, an attachment mechanism can be applied to the self-standing metal object for mounting to the battery surface. In the case of a standard solar cell module, a reactive metal layer such as a burn through silver paste can be applied to the surface of the metal object to be coupled to the solar cell. The reactive paste provides an electrical connection between the metal article and the semiconductor layer and can be applied thinly. The paste can be applied to the electroformed metal article by, for example, screen printing. The amount of silver applied to the grid is much smaller than that required to form the metallization layer only by self-burning. Since the burn-through paste is applied to the grid instead of the solar cell, the electrical coupling between the grid and the solar cell is self-aligned. That is, there is no need to align the fingers of the electrical conduit with the conductive paste lines that have been applied to the solar cells, thereby simplifying the manufacturing process. Moreover, in the traditional method, Always apply additional paste to ensure alignment with electrical contacts. In contrast, the method allows the application of silver paste only when necessary. Other methods of utilizing attachment mechanisms include electroplating, electroless plating, wave soldering, physical vapor deposition techniques such as evaporation or sputtering; via inkjet dispersion or pneumatic dispersion techniques; or thin film transfer techniques, such as The grid is stamped onto a molten solder or metal film.

While some solar cell types use dielectric ARC, other types use conductive ARC, such as TCO. In the case of TCO type solar cells, such as those coated with indium tin oxide (ITO), the attachment mechanism in step 740 can be a solder, such as a low temperature solder. The solder is applied to the surface of the grid that is to be in contact with the battery. By applying solder to the grid, the amount of solder used is minimal, thereby reducing material costs. In addition, the solder aligns itself with the mesh. The type of solder on the metal object can be selected to achieve the following characteristics, such as good ohmic contact and electrical conductivity, strong adhesion, rapid heat dissipation, low coefficient of thermal expansion (CTE) mismatch with the target surface, robust mechanical stress release, high Mechanical strength, robust electromigration barriers, adequate wettability, and chemically stable materials between the metal electroformed grid and the surface of the solar cell interact with the barrier. In one embodiment, a no-clean solder can be applied. In another embodiment, an electroless or electroplated low melting point metal or alloy such as, but not limited to, indium, indium tin, indium antimonide, lead tin silver copper, lead tin silver, and lead indium may be applied to the grid. In yet another embodiment, the solder paste can be printed onto the grid. Solder paste may require a drying process before the grid is coupled to the solar cell. In a further embodiment, the tip of the grid, ie the bottom surface, may be impregnated or immersed in a liquid solder that will optionally be attached to the surface of the mesh.

While the attachment mechanism has been described above as being applied to an electroformed article, in other embodiments, step 740 can include applying a burn through paste or solder material to the solar cell. The electroformed article can then be joined to the conductive pattern by a paste or solder. Indium metal or indium alloy can be applied to the article as appropriate to prepare the metal object for contact with the battery. Indium can be plated onto the surface of the mesh by dipping the mesh into the electrolyte while providing current. In another embodiment, the grid can be applied by immersion in an indium solution by electroless plating. The grid can first be immersed in a flux flux that removes the oxide on the tip of the grid and then dipped the grid into the indium tin solder so that the indium tin solder only wets the tip of the grid . In another embodiment, the grid can be dipped into an indium tin paste followed by an annealing step to again coat only the tips of the grid. Preserving precious indium with indium coating only the tip rather than the entire grid while still obtaining a contactable surface. Once the indium is tipped, the fingers or components of the electroformed article can be aligned with the burn-through paste or solder on the cell by, for example, optical alignment marks on the edges of the solar cell.

In other embodiments, metal objects can be used in a back contact type solar cell using similar methods, such as those depicted in FIG. 1B. In step 740, an attachment mechanism, which may typically be solder, may be applied to a metal object or solar cell, and then the metal object is brought into contact with the battery. The attachment mechanism is heated to electrically couple the metal object to the battery. In one embodiment of the back contact solar cell, the electroformed component of the first metal object can be coupled to the p-type region on the back surface of the cell while the electroformed component of the second metal object can be coupled to the n-type region. . For example, metal objects can be assembled to have a linearity as in Figure 6A. a finger and a finger of the first metal object and a finger of the second metal object.

After the attachment mechanism has been applied to the metal object, in step 750, the metal object is coupled to the surface of the battery or semiconductor device. The metal object is brought into contact with the surface of the solar cell. If the burnt silver paste is placed at the tip of the mesh article, the assembly is heated to a burnout temperature of the paste, such as at least 400 ° C or at least 800 ° C. The grid can be fixed mechanically by using rollers or splints during firing. Once the burnt paste is solidified, the adjacent solar cells in the module can be interconnected. In the case of a solder-finished grid, the grid is coupled to the solar cell in a similar manner and heated to the temperature required for the particular solder, typically between 100 ° C and 300 ° C. A heat and/or pressure program in the atmosphere or vacuum can be used to reflow the solder and form a joint between the metal object and the solar cell.

In some embodiments, the individual grid or metal object may be attached to the solar cell prior to deposition of the anti-reflective coating layer after plating through the desired barrier layer. In a standard battery, the grid can be contacted with an emitter surface (e.g., doped with germanium) and heated to produce a nickel halide chemical bond. An ARC such as a nitride may be deposited after the grid is attached, which may then be deposited as appropriate in step 760. The grid bus bar can then be connected to another battery in the module. The embodiment of attaching the grid in front of the ARC layer eliminates any need to use silver to burn through the paste. Furthermore, this embodiment can be applied to a germanium heterojunction solar cell. For example, a self-standing metal object such as a grid can be coupled to the surface of the amorphous junction battery amorphous layer. It can then be heated to form a nickel telluride bond and the ITO layer can be deposited on a subsequent grid.

After the completed photovoltaic cells have been formed in step 750, a plurality of cells forming a solar module can be interconnected in step 770. In some embodiments, bus bars or ears that have been partially electroformed as one of the metal articles can be used for such interconnections.

It can be seen that the self-standing electroformed metal articles described herein are suitable for a variety of battery types and can be inserted at different points within the manufacturing sequence of the solar cells. Additionally, an electroformed electrical conduit can be used on the front or back surface of the solar cell or both. When an electroformed article is used on both the front and back surfaces, the electroformed articles can be applied simultaneously to avoid any thermal expansion mismatch that can cause mechanical bending of the battery.

8A-8B are schematic illustrations of an exemplary photovoltaic cell 800 fabricated to have a self-standing metal object 810. The metal article 810 in this embodiment includes an electroformed component 812 and a frame member 814 that spans the edge near the perimeter of the electroformed component 812. Electroformed elements 812 are shown as parallel lines that intersect perpendicularly in this embodiment to form a continuous grid pattern, but in other embodiments, the electroformed elements can be grouped into lines that intersect at other angles, or Group parallel lines, or other patterns. The tip of the electroformed component 812 has an applied attachment material 820, such as solder or burn through silver paste. The attachment material 820 electrically couples the metal object 810 to the photovoltaic device 830, wherein the photovoltaic device 830 can include a light incident layer 832 (eg, ARC and/or TCO), an active region 834 (emitter and base), and a rear contact. Layer 836. 8B shows another embodiment of a photovoltaic cell 800 in which layer 832 is an ARC, wherein the attachment material 820 is a silver paste that has been burned through the ARC. In FIGS. 8A-8B, an encapsulant (not shown) may be applied to the metal object 810 to seal the completed photovoltaic cell 800 by Frame member 814 forms an interconnection with other batteries. In other embodiments, the second metal object 810 can be coupled to the back contact layer 836 that is a non-light incident surface in a similar manner to provide electrical contacts of opposite polarity to the photovoltaic cell 800.

8C-8D show simplified schematic diagrams of an exemplary back contact solar cell 801 fabricated as a self standing metal object. In the cross-sectional view of FIG. 8C, the solar cell 801 includes a transparent layer 831 (eg, ARC), a semiconductor substrate 833, doped regions 835 and 837, and a passivation layer 840. The two self-standing metal objects 850 and 860 have electroformed components disposed in an alternating manner. The electroformed components of metal objects 850 and 860 provide electrical contact to doped regions 835 and 837, respectively, via apertures 845 in passivation layer 840. FIG. 8D shows a top view of metal objects 850 and 860 for use in solar cell 801. Metal object 850 has fingers 852 that are interdigitated with fingers 862 of metal object 860. The frame member 854 of the metal article 850 and the frame member 864 of the metal article 860 serve as electrical connection points for the metal objects and also provide mechanical stability.

9A-9B illustrate yet another embodiment in which the shielding effect of the solder applied between the metal object and the solar cell can be reduced. 9A shows a vertical cross-sectional view of a standard solder joint 910 that can be produced by soldering a metal component 920 having a linear cross section to a solar cell 930. Since the solder naturally forms a wetting angle between the surfaces joined by it, the solder has an occupied area of the width "F1". The width of this footprint will block light from entering the solar cell 930 and thus cause shadowing. In FIG. 9B, the cross-sectional shape of the electroformed component 925 is different than that of the electroformed component 920 because the electroformed component 925 has a chamfered corner 927 on its lower surface. inverted The keratinization changes the wetting angle of the solder joint 910 such that the occupied area width "F2" is smaller than "F1". Thus, the customized electroformed component 925 shape can reduce shadowing. The ability to tailor the cross-sectional shape of the electroformed component 925 can be achieved by using an electroformed mold core as described in the various embodiments above. Shaped bodies such as chamfering, filleting, micropits, thin tumors, and the like may be formed in the mold core to impart such topography to the electroformed part to be fabricated.

10A-10B show top views of another embodiment of reducing shadowing from solder applied to metal objects. FIG. 10A shows a conventional solder joint 1010 applied to two oblique intersecting linear segments 1020. The total footprint of the solder joint 1010 has a width "F3". Figure 10B shows an electroformed component 1025 in which a concave cut-out topography body 1027 has been incorporated into a corner, wherein the electroformed component 1025 intersects through the topography of the mold core from which the component 1025 has been formed. The concave topography 1027 changes the wetting angle of the solder 1010 such that the occupied area width "F4" is reduced compared to "F3". Shapes other than the concave topography shown herein may be employed. Thus, the ability to tailor the shape of the electroformed component by incorporating the topography into the forming core reduces the shielding of the solder used to couple the electroforming component to the photovoltaic surface.

In another embodiment shown in Figures 11A-11C, the core portion in which the metal object is formed may become part of the final semiconductor device. 11A shows a cross-sectional view of a mold core 1100 similar to the mold core 400 of FIG. 4 described above having a metal base 1120 and a dielectric layer 1130 having a pattern for forming an electroformed component 1110. Electroformed component 1110 has been formed in dielectric layer 1130 during the electroforming process. In addition, the plating thickness may also exceed the height of the core pattern to form the overplating head 1112. In other embodiments, no Overplating is performed, as in electroformed component 1111. When the metal object comprising the electroformed component 1110 is removed from the mold core 1100, the dielectric layer 1130 and the electroformed component 1110 can be peeled from the core metal base 1120 as indicated by arrow 1140. The head 1112 can help secure the electroformed component 1110 to the dielectric layer 1130.

In FIG. 11B, a separate metal object 1150, which is a combination of electroformed components 1110 and surrounded by a dielectric layer 1130, can then be coupled to a semiconductor surface to form, for example, a photovoltaic cell. One embodiment of solar cell 1160 is depicted in the simplified schematic of Figure 11C. Solar cell 1160 includes a semiconductor assembly 1170. The metal article 1150 is coupled to the semiconductor assembly 1170 and is covered with an encapsulant 1180 and a window layer 1190 such as an anti-reflective coating. The encapsulant 1180 can be, for example, ethylene vinyl acetate (EVA), thermoplastic polyolefin (TPO), or polyvinyl butyral (PVB). The dielectric layer 1130 of Figures 11A-11C can be selected to be suitable for a suitable semiconductor application. In the case of photovoltaic cells, the characteristics of the transferable dielectric material will depend on the reliability specifications of the intended solar module. Since the dielectric material will be incorporated into the module, it should have durability that withstands the life of the solar module. The dielectric material should also be transparent to allow light to be transmitted to the solar cell and should also resist diffusion of copper into the cell. One type of suitable dielectric material is, for example, a solder resist dielectric material known in the electronic packaging industry.

In other embodiments, the metal articles described herein can be combined with a polymer sheet to form a polymer layer. Figure 12 shows an embodiment of the method in which a metal object having an electroformed component 1210 has been formed by a mold core 1220. The electroformed component 1210 can be assembled, for example, as a set of parallel lines, or as a set of intersecting lines forming a grid. For this embodiment, the electroformed component 1210 has been plated. To form a rounded head 1212 at its top surface, as described above in relation to electroformed component 312 of Figure 3B. The polymer sheet 1230 is placed on the surface of the mold core and used to remove the electroformed component 1210 from the mold core 1220. Figure 12 shows the state in which the polymer sheet 1230 and the electroformed component 1210 have been lifted from the mold core 1220. The polymer sheet 1230 is in contact with the mold core such that the head 1212 of the electroformed component 1210 is at least partially embedded in the polymer sheet 1230. The head 1212 allows the polymer sheet 1230 to grip the electroformed component 1210 due to its larger area, and the head 1212 can also serve as an anchor point. It is noted that although the head 1212 is embedded with a curved surface, other shapes may be employed. In addition, for some metal objects and mold cores, overplating may not be required. The polymer sheet 1230 having the insert head 1212 of the electroformed component 1210 is lifted from the mold core 1220, thereby pulling the head 1212 up, thereby lifting the electroformed component 1210 of the metal object from the mold core 1220. The bottom of the electroformed component 1212 remains exposed from the polymer sheet 1230 and is suspended from such anchor points, thereby allowing subsequent coating or plating thereof to be applied as desired.

The polymer sheet 1230 can be made of, for example, EVA, TPO, or PVB. The polymer sheet 1230 may optionally constitute a substrate layer 1232 covered by an adhesive layer 1234. The viscous layer 1234 faces the mold core to engage the electroformed component 1210. The substrate layer 1232 can be, for example, a polyethylene, polyester or polyester film (eg, Mylar®), and the adhesive layer 1234 can be, for example, EVA or TPO. If the polymer sheet 1230 includes a viscous material, the mold core 1220 can include an optional release layer 1225 to allow the polymer sheet 1230 to be easily peeled from the mold core 1220. Release layer 1225 can be, for example, a fluoropolymer or other low viscosity material. The adhesive layer 1234 is formed to have a thickness that allows the head 1212 to be at least partially embedded therein.

In some embodiments, the polymer sheet 1230 is primarily used to power The casting element 1210 is removed from the mold core, such as as a transfer material. The polymer sheet 1230 can then be separated from the electroformed component 1210, resulting in a self-standing metal article as described in the above embodiments. The use of polymer sheets to remove metal objects from the conductive mold core allows the processing procedure to become automated, thereby enabling high throughput. The polymer sheet can also provide support for electroformed metal articles when the article is subjected to other manufacturing steps. For example, since the bottom surface of the electroformed component 1210 remains exposed after being drawn from the mold core 1220, the polymer sheet 1230 can be used to hold the metal object while the bottom surface is, for example, plated with a barrier layer or soldered or burned. apply. The polymer sheet 1230 can also provide additional mechanical support to maintain the dimensions of the mesh during operation.

In other embodiments, the polymer sheet can be one of the components in which the metal object will be placed in the final semiconductor device. 13A-13B show an exemplary embodiment in which a polymer layer 1315 is placed over a semiconductor component 1370 to form a photovoltaic cell 1300. In this embodiment, polymer layer 1315 is used as an electrical conduit for the surface behind photovoltaic cell 1300. However, the procedures described in Figures 13A-13B can also be used as a polymer layer 1315 for a front contact or front and back contact. Polymer layer 1315 includes polymer sheet 1330 and electroformed component 1310, which are similar to polymer sheet 1230 and electroformed component 1210 of FIG. The semiconductor component 1370 can be, for example, a solar cell having a layer of layers such as an active region, a back contact, and a TCO layer. In some embodiments, the polymer layer 1315 can have a reactive metal layer (not shown) applied to the exposed surface of the electroformed component 1310, or a reactive metal layer can be applied to the receiving electroforming component. The surface of the semiconductor component 1370 of 1310. The polymer layer 1315 is mechanically and electrically coupled to the semiconductor component 1370 using heat and pressure. Applied The heat and pressure push the grid into the polymer material 1330 as shown in Figure 13B. Electroformed component 1310 establishes a mechanical anchor point in polymer 1330 and provides robust stabilization of electroformed component 1310 within polymer layer 1315. The polymeric material 1330 is selected to have the desired characteristics of the solar encapsulant material, particularly in other desirable limitations depending on the type of battery, such as clarity, durability, wettability, and corrosion resistance. Materials for the polymer sheet 1330 can be, for example, EVA, TPO, PVB, and ionic polymers.

14 is an illustrative flow diagram 1400 of using a polymeric substrate in combination with an electroformed metal article such as a mesh or mesh. In step 1410, a metal object is fabricated by an electroforming process using a conductive mold core having a preformed pattern. In step 1420, the metal article is in contact with the polymer sheet, wherein one of the metal objects is partially embedded within the polymer sheet. In step 1430, the polymer sheet and the electroformed component are lifted or peeled from the mold core to separate the polymer layer from the mold core, wherein the polymer layer is a polymer sheet and a portion of the electroformed grid partially contained therein. Composite material. In optional case 1440, additional plating or other procedures may be performed on the exposed portions of the electroformed component. For example, if a nickel layer is not added during the electroforming process, step 1440 can include plating nickel or another barrier material onto the exposed portion of the grid. Step 1440 can also include a cleaning step, such as removing oxides to prepare a grid for lead bonding.

If a polymer sheet is primarily used as the transfer material, the polymer sheet can be separated from the metal article in step 1450. The metal object can then be processed into a photovoltaic cell or other semiconductor device in step 1460, which can include performing steps 740 through 770 of FIG. In other embodiments of the apparatus for incorporating the polymer sheet into the process, in step 1470, as in step 740 of FIG. Description The attachment mechanism is applied to a grid or semiconductor device. In step 1480, the polymer layer is then coupled to the semiconductor device, such as by using heat and pressure. This bonding procedure causes the polymeric material to encapsulate the electroformed grid and also electrically couple any solder or burn through between the grid and the solar cell. The bonding process can include subjecting the battery and polymer layer to a lamination procedure that uses vacuum, elevated temperature, and pressure. Under lamination conditions, the solder reflows and forms electrical contacts between the cell and the polymer-supported metal grid while the polymer bonds to the cell surface and forms a robust mechanical contact. The photovoltaic cell can then be completed in step 1490 by performing any processing steps, such as applying an anti-reflective layer and forming an interconnection with other cells in the solar module. The procedure of flowchart 1400 applies to both front and back side connections, as well as various types of solar cells, including standard, non-standard TCO coatings and back contact (eg, interdigitated back contact) batteries.

In yet another embodiment, the metal article disclosed herein can be used as a mask for a conductive layer on a semiconductor surface, wherein the metal object is then self-aligned with the pattern created on the conductive layer. Figure 15A shows a perspective view of a portion of a semiconductor device 1510 that includes a layer for a solar cell. The semiconductor device 1510 has a conductive metal layer 1520 placed on its top surface. Conductive metal layer 1520, also known in the industry as a contact layer, can substantially cover the entire surface of semiconductor device 1510. The surface covered by the conductive metal layer 1520 may be the light incident top surface of the solar cell. The conductive metal layer 1520 can be, for example, a metal film deposited on a standard solar cell shortly before deposition of the ARC layer or via burn-through of the metal layer. Conductive layer 1520 can be another TCO layer. In an embodiment, the conductive layer 1520 can be thin with titanium deposited thereon. Floor. Conductive metal layer 1520 is selected to form good ohmic contact with semiconductor device 1510 and provides excellent adhesion to semiconductor device 1510 and to a metal mesh to be subsequently attached. Conductive metal layer 1520 can be, for example, a combination of titanium, tungsten, chromium, molybdenum, or the like, and can be provided on a semiconductor device using any method known in the art, including deposition methods such as physical vapor deposition or electroplating. In some embodiments, the thickness of the conductive metal layer 1520 can be only the thickness required to provide a uniform film that maintains the desired electrical and mechanical properties.

The metal object embodied in FIG. 15B as grid 1530 can be mechanically and electrically coupled to an assembly comprising semiconductor device 1510 and conductive metal layer 1520. Such coupling (not shown) may be by adhesion of solder paste, conductive adhesive or conventional solder such that the metal mesh 1530 has good electrical and mechanical contact to the conductive metal layer 1520. Solder, solder paste or viscous material can be applied to the mesh 1530, such as the bottom surface of the mesh 1530. This grid 1530 is designed to be highly conductive while still providing a relatively low amount of shielding on the battery. Grid 1530 can, for example, have a high height to provide sufficient conductivity, but a narrow width to minimize shadowing as much as possible.

A metal object attached to the conductive metal layer 1520 can be used as a mask to pattern the conductive metal layer 1520 such that a majority of the area of the solar cell can be cleaned for light absorption. For example, as shown, the masking region 1540 is formed directly below the grid 1530 while the exposed portion 1545 includes the remainder of the grid 1530 in the conductive metal layer 1520. The exposed portion 1545 can be removed such that the conductive metal layer 1520 is patterned into the shape of the grid 1530. The etch can be performed, for example, by a wet chemical etching process, a dry etching process such as reactive ion etching, or a physical etching method such as, but not limited to, ion milling. The exposed portion 1545 is removed and the conductive metal layer 1520 is patterned. The etching process can remove all or a portion of the exposed area 1545.

FIG. 15C shows the assembly after etching, such that only the masking region 1540 remains on the surface of the semiconductor device 1510 in this embodiment. The shadow region 1540 has a pattern substantially similar to the grid 1530 and coincides with the grid 1530. Thus, metal grid 1530 provides a chemically resistant mask in the case of wet or reactive ion etching, and a mechanical mask in the case of physical etching, thereby allowing a separate metal object to be coupled to the semiconductor assembly. Connect and align. In Figure 15D, another embodiment is shown in which the semiconductor device 1510 is a standard battery, and wherein the grid 1530 has been coupled to a turn instead of a TCO. After etching, a nitride layer 1550 has been deposited over the area previously occupied by the exposed portions of the conductive metal layer 1520 to form an ARC layer for photovoltaic cells. Although not shown, the metal mesh 1530 can also be coated.

FIG. 16 depicts an exemplary flow diagram 1600 of using a metal object as a mask. In step 1610, a layer of conductive metal is provided on the surface of the semiconductor material. In step 1620, the metal object is electrically and mechanically coupled to the conductive metal layer. As described above and as shown, for example, in Figures 2-7, the metal article can be electroformed in a conductive mold core having a preformed pattern. A portion of the surface of the semiconductor material covered by the metal object is a masked area, and an uncovered portion is an exposed area. In step 1630, the exposed regions are partially or completely removed by, for example, one of the various etching methods described in relation to Figures 15B-15C. The assembly obtained with a patterned conductive metal layer that is self-aligned with the metal object can now be further processed to form a fabricated semiconductor device assembly such as a solar cell. By using the grid as a mask, the step is The total number of steps is significantly reduced compared to conventional masking techniques where separate masking and patterning procedures are required to pattern the contact layer. In addition, since the mask is self-aligned with the patterned wire being fabricated, the alignment between the metal mesh and the wire needs to be eliminated. The metal grid also provides an increased level of robustness compared to conventional burn through silver contacts.

Thus, it can be seen that the use of electroformed metal articles as described herein allows for the preparation of a variety of different photovoltaic cells and solar cell modules. Electroformed metal objects can be inserted at different points within the manufacturing sequence. In addition, such metal articles can be specifically designed to efficiently produce batteries and modules having additional combinations of benefits and characteristics that are not currently readily achievable. For example, improved durability can be obtained because the metal article can be a single workpiece that spans across and across substantially the entire surface of the cell. In particular, if the solar cell is broken, such as during processing or module fabrication, such metal objects will remain intact due to the grid-like nature of the metal object, with minimal functional loss to the battery. In addition, the traversal of metal objects across the surface of the battery can reduce the effects of solder joint failure. Moreover, since the electroformed metal article can be made to have a uniform and predictable thickness throughout, the current can be averaged across the battery. The average distribution of such currents substantially reduces the hot spots established on the surface of the cell, which is now a major cause of degradation and damage to solar cells.

In some embodiments, the flexible module can be prepared as shown in Figures 19-21 by incorporating a particular design topography into the metal object. Such a module can be folded into a compact form and made easy to carry in, for example, a backpack for subsequent deployment and use, such as at a more remote location. In other real In an embodiment, the flexible module can be folded for storage, such as the installation of a roof or awning.

For example, Figure 19 shows a module 1900 folded along parallel lines. In this embodiment, the module 1900 includes 32 separate cells 1910 each including a metal object 1920 attached to a semiconductor substrate. The battery 1910 is disposed on a backing substrate 1930 which may be made of a conventional backing material for photovoltaic modules and may be rigid or flexible. The backing substrate 1930 is divided, such as by folding or scoring, to form fold lines 1941, 1942, and 1943. The battery 1910 is electrically connected in series, in a zigzag order from the first battery 1910a to the fourth battery 1910b, to the fifth battery 1910c, to the eighth battery 1910d, and the like, to the final battery 1910e. The electrical connection between the batteries 1910 can be achieved using a topography of the metal object as described above, such as by using the interconnecting elements 660 and 680 of Figures 6F-6G.

A foldable interconnect 1950 is provided for the interconnection between the cells across the fold lines 1941, 1942, and 1943 in FIG. For example, the connection portion from the battery 1910d to the next battery passes over the fold line 1941. Accordingly, the metal object for the battery 1910d is designed to have a foldable interconnection 1950, and the interconnection between the batteries 1910b and 1910c does not cross a fold line, so there is no interconnection between the batteries thereof. . The foldable interconnect can be a solid sheet such as a sheet or strip of copper having a thickness sufficient to allow for easy folding without cracking or cracking. Thus, the foldable interconnect 1950 acts as a living hinge. In some embodiments, the foldable interconnect 1950 can include an opening 1960 that provides additional flexibility. The foldable interconnect 1950 can be an elongated version of the interconnect, for example, between unfolded cells. In some embodiments The foldable interconnect 1950 can be an integral component that is electroformed into portions of a metal object. In other embodiments, the foldable interconnect 1950 can be an element formed separately from the metal article, such as by electroforming or stamping and subsequent bonding to a metal object of the desired battery. The battery 1910 and the foldable interconnect 1950 are disposed on the substrate 1930 as shown, with the interconnect 1950 spanning the fold lines 1941, 1942, and 1943, and the resulting module 1900 can be folded. In the embodiment of Fig. 19, the fold lines 1941 and 1943 are convex folds, while the fold line 1942 is a concave fold, as indicated by the curved arrow. Thus, the module 1900 is folded such that the plates A, B, C, and D are stacked on each other.

Figure 20 shows another embodiment of a flexible module 2000 similar to that of Figure 19, but with a greater number of batteries. The module 2000 has fold lines 2041, 2042, and 2043 between the boards A, B, C, and D, and the foldable interconnect 2050 passes over the fold lines 2041, 2042, and 2043. The module 2000 can be folded into an accordion type similar to the module 1900, such as having fold lines 2041, 2042, and 2043 alternating between a convex fold and a concave fold. Also shown in Figure 20 is a hole 2070 that can have a drawstring such as a cable or wire to squash the module into a folded configuration. The aperture 2070 in this embodiment is disposed at the edge of the module 2000 and adjacent to the fold lines 2041, 2042, and 2043 to apply a pulling force at the folded joint. The aperture 2070 can include a reinforcement such as an eyelet or a buttonhole to enhance durability. The cable mounting system as described for the folding module 2000 can be used, for example, for opening and stowing of an awning type photovoltaic module.

Although the foldable interconnects of Figures 19 and 20 are shown as being generally rectangular, other shapes are possible. In addition, although the foldable interconnects of Figures 19 and 20 are shown positioned along the edge of one of the cells, and around Most of the edge length, but in other embodiments, the foldable interconnect may extend only along a portion of one of the edges of the battery, or may be eccentrically disposed along the edge, such as at a corner. The specific configuration of the foldable interconnect can be designed to accommodate the folded geometry of a particular module.

Figure 21 shows yet another embodiment of a flexible module 2100 having bi-directional folding capabilities. In this embodiment, in addition to the vertical fold lines 2141, 2142, and 2143, the module 2100 has a horizontal fold line 2145 extending approximately through the line in the module 2100. Thus, the foldable interconnect 2151 is used between adjacent cells disposed across the fold line 2145. The module 2100 can then be folded into a compact size in two directions, similar to a road map. For example, the module 2100 can be folded in half along the fold line 2145 and then accordion-folded along the fold lines 2141, 2142, and 2143, as indicated by the curved arrows.

Figure 22 illustrates an alternative method of forming a flexible module that utilizes mechanical support provided by metal objects attached to the battery. For example, the semiconductor substrate 2210 of the solar cell 2200 can be scored or replaced with a sheet that is shredded along the dashed line 2240 with the metal article 2220 attached thereto. As long as the grid of metal objects 2220 remains intact, the separate sheets of semiconductor substrate 2210 will remain attached to battery 2200, and thus battery 2200 can be bent or flexed along tangent 2240. Additional scoring and tangents are formed to provide an additional degree of flexibility. For example, in some embodiments, the semiconductor substrate can be scored into 2 to 36 sections. In this manner, individual cells having attached metal objects as described herein can be made flexible, allowing the battery to be adapted along a curved or uneven surface as part of a module, particularly in a foldable manner. When the joints are combined, as shown in Figures 19-21. Other amount External benefits and characteristics will be apparent to those skilled in the art, given the detailed description provided herein.

While the present embodiments have been described primarily with respect to photovoltaic cells, such methods and devices are also applicable to other semiconductor applications, such as rewiring layers (RDL) or flexible circuits. Moreover, the flowchart steps can be performed in a different order and can include additional steps not shown.

Although the specification has been described in detail with reference to the embodiments of the present invention, it will be understood that These and other modifications and variations of the present invention can be made by those skilled in the art without departing from the scope of the invention, which is more specifically described in the appended claims. In addition, those skilled in the art will understand that the above description is by way of example only and is not intended to limit the invention.

Claims (47)

An electrical component for photovoltaic cells, the electrical component comprising: a metal object comprising a plurality of electroformed components, the plurality of electroformed components comprising a battery interconnect component integral with a continuous grid, the continuous The grid has a plurality of first elements intersecting the plurality of second elements, wherein the battery interconnect elements are configured to couple the grid directly to an adjacent battery; wherein the battery interconnect elements span the continuous grid a length, and comprising a first zone having a plurality of segments, and a second zone coupled to the plurality of segments coupled to the plurality of segments; wherein each electroformed component is in the continuous grid Having a height and a width, wherein the ratio of the height to the width is an aspect ratio, and wherein a plurality of the electroformed components have an aspect ratio greater than one; wherein the electroformed components are interconnected and integrated Making the metal object a single self-standing workpiece, and wherein the electroforming elements are assembled as an electrical conduit for a light incident surface of a photovoltaic cell, and the continuous mesh is in contact with the light incident surface And the battery is interconnected The components are assembled to extend beyond the light incident surface. The electrical component of claim 1 wherein the aspect ratio is between about 1 and about 10. The electrical component of claim 1 wherein the plurality of electroformed components have a pattern determined by a conductive core formed by the electroformed components. The electrical component of claim 3, wherein at least one of the electroformed components comprises a plated portion formed over an outer surface of one of the conductive mold cores. The electrical component of claim 4, wherein the overplated portion has a rounded top surface. The electrical component of claim 1 wherein the plurality of electroformed components comprise a conductive coating on at least a portion of the electroformed components. The electrical component of claim 6 wherein the electrically conductive coating comprises nickel, indium, tin, antimony, tungsten, cobalt, silver, solder, solder paste, or combinations thereof. The electrical component of claim 1, wherein the continuous mesh further comprises a frame component. The electrical component of claim 8, wherein the frame component comprises a bus bar that spans at least a portion of the continuous mesh. The electrical component of claim 1, wherein the metal object further comprises an electroformed region coupled to the second region of the interconnecting component, and wherein the electroformed region is assembled to function as a second photovoltaic cell An electrical conduit on one of the surfaces. The electrical component of claim 1, wherein the plurality of electroformed components comprise a plurality of substantially parallel first segments that intersect a plurality of substantially parallel second segments. The electrical component of claim 11, wherein the plurality of substantially parallel first segments and the plurality of substantially parallel second segments are linear and perpendicularly intersect. The electrical component of claim 1, wherein the plurality of electroformed components are each The coplanar plane is such that a first coplanar electroformed component has a first cross section that overlaps a majority of a second section of one of the second coplanar electroformed components. The electrical component of claim 1, wherein the first zone of the interconnecting component is between the continuous mesh and the second zone. An electrical component for a photovoltaic cell comprising: a metal object comprising a plurality of electroformed components, the plurality of electroformed components comprising a battery interconnect component integral with a continuous grid, the continuous The grid has a plurality of first elements intersecting the plurality of second elements, wherein the battery interconnect elements are configured to couple the grid directly to an adjacent battery; wherein the battery interconnect elements span the continuous grid a length, and comprising a first zone having a plurality of segments, and a second zone coupled to the plurality of segments coupled to the plurality of segments; wherein each electroformed component is in the continuous grid Having a height and a width, wherein the ratio of the height to the width is an aspect ratio, and wherein a plurality of the electroformed components have an aspect ratio greater than 0.1; wherein the electroformed components are interconnected and integrated Making the metal object a single self-standing workpiece, and wherein the electroforming elements are assembled as an electrical conduit for a light incident surface of a photovoltaic cell, and the continuous mesh is in contact with the light incident surface And the battery mutual Element to group with lines extending beyond the light incident surface. The electrical component of claim 15 wherein the aspect ratio is between about 0.1 and about 1. The electrical component of claim 15 wherein the plurality of electroformed components have The electroformed component is formed in a pattern of one of the conductive mold cores. The electrical component of claim 17, wherein at least one of the electroformed components comprises a plated portion formed over an outer surface of one of the conductive mold cores. The electrical component of claim 18, wherein the overplated portion has a rounded top surface. The electrical component of claim 15 wherein the interconnecting element has a height that is less than one of the heights of the continuous grid. The electrical component of claim 15 wherein the continuous mesh further comprises a frame component. The electrical component of claim 21, wherein the frame component comprises a bus bar that spans at least a portion of the continuous mesh. The electrical component of claim 15 wherein at least one of the plurality of electroformed components has a tapered cross-sectional shape that is achieved in the direction of the height of the electroformed component. The electrical component of claim 15 wherein the first zone of the interconnecting component is between the continuous mesh and the second zone. A method of forming an electrical component for photovoltaic cells, the method comprising the steps of: i) electroforming a metal object on a conductive mold core, wherein the conductive core has an outer surface comprising at least one preformed pattern, The preformed pattern includes a continuous grid pattern coupled to a battery interconnect pattern, wherein the metal object comprises a plurality of formed in the preform pattern Electroformed elements comprising a battery interconnect element coupled to a continuous grid having a plurality of first elements intersecting the plurality of second elements, and wherein the battery Connecting the components to directly couple the mesh to an adjacent battery; and ii) separating the metal object from the conductive die, wherein the plurality of electroformed components are interconnected such that the metal object is Forming a single self-standing workpiece when the conductive cores are separated; wherein the preformed pattern has a height and a width, wherein the ratio of the height to the width is an aspect ratio, and wherein the preformed pattern has an aspect ratio greater than one And wherein the plurality of electroformed components are assembled as an electrical conduit for a light incident surface of a photovoltaic cell. The method of claim 25, wherein the aspect ratio is between about 1 and about 10. The method of claim 25, wherein the electroforming step comprises overplating the electroformed components such that the electroformed components extend over the outer surface of the conductive core. The method of claim 25, wherein the step of electroforming the metal article comprises contacting the outer surface of the mold core with a first solution comprising a salt of a first metal, wherein the first metal comprises one of the first A metal layer is formed within the preformed pattern. The method of claim 25, wherein the plurality of first elements and the plurality of second elements comprise a plurality of substantially parallel first elements intersecting the plurality of substantially parallel second elements, wherein the plurality The first component and the plurality of second components are coplanar such that one of the first components has There is a first section that most overlaps a second section of one of the second elements. The method of claim 29, wherein the plurality of first elements each have a width between about 10 microns and about 5000 microns, and the plurality of second elements each have between about 10 microns and about 5000 A width between microns. The method of claim 29, wherein the plurality of substantially parallel first elements and the plurality of substantially parallel second elements are linear and perpendicularly intersect. The method of claim 25, wherein the preformed pattern has a tapered cross-sectional shape that is wider on the outer surface of the conductive mold core. The method of claim 25, wherein the conductive core has a first outer surface and a second outer surface opposite the first outer surface, wherein the first outer surface comprises a first preformed pattern The second outer surface includes a second preformed pattern. The method of claim 33, wherein the first preform pattern and the second pre-pattern are different from each other. The method of claim 25, wherein the conductive core is metallic, and wherein at least one of the preformed patterns comprises at least one pattern element as a cavity in the conductive core. The method of claim 35, wherein the pattern element is an intersecting trench having three metal sides. The method of claim 35, wherein the conductive mold core comprises a first layer on the outer surface, and wherein the first layer comprises at least one of a low viscosity material or a dielectric material. The method of claim 37, wherein the first layer extends at least partially into the preformed pattern. A method of forming an electrical component for photovoltaic cells, the method comprising the steps of: i) electroforming a metal object on a conductive mold core, wherein the conductive core has an outer surface comprising at least one preformed pattern, The preformed pattern includes a continuous grid pattern coupled to a cell interconnect pattern, wherein the metal object comprises a plurality of electroformed elements formed in the pre-formed pattern, the plurality of electroformed elements comprising a coupling to a continuous a battery interconnection element of the grid having a plurality of first elements intersecting the plurality of second elements, and wherein the battery interconnection elements are assembled to directly couple the grid to an adjacent battery And ii) separating the metal object from the conductive mold core, wherein the plurality of electroformed components are interconnected such that the metal object forms a single self-standing workpiece when separated from the conductive mold core; wherein the preformed pattern Having a height and a width, wherein the ratio of the height to the width is an aspect ratio, and wherein the preformed pattern has an aspect ratio greater than 0.1; and wherein the plurality of electroformed component systems With a light incident surface as a photovoltaic cell, one of an electrical conduit. The method of claim 39, wherein the electroforming step comprises overplating the electroformed components such that the electroformed components extend over the outer surface of the electrically conductive core. The method of claim 40, wherein the overplating step forms a rounded top. The method of claim 40, wherein the top surface of the overplated portion provides an optical surface that assists in the collection of light for the photovoltaic cell. The method of claim 39, wherein the preformed pattern has a tapered cross-sectional shape that is wider on the outer surface of the conductive mold core. The method of claim 43, wherein the electroforming step comprises overplating the electroformed components such that the electroformed components extend over the outer surface of the electrically conductive core. The method of claim 39, wherein the battery interconnect component comprises a bus bar. The method of claim 45, wherein the battery interconnect element has a height that is less than a height of the continuous grid. The method of claim 39, wherein the aspect ratio is between about 0.1 and about 1.