Laser-assisted metallization process for solar cell string connection

Abstract

The present invention describes metallization of semiconductor substrates using laser beams and the resulting structures, such as microelectronic devices, semiconductor substrates and / or solar cells, solar cell circuits, solar cell strings and solar cell arrays. The solar cell string may include a plurality of solar cells. The plurality of solar cells may include a substrate and a plurality of semiconductor regions disposed in or on the substrate. A plurality of conductive contact structures are electrically connected to the plurality of semiconductor regions. Each conductive contact structure includes a locally deposited metal portion, the locally deposited metal portion being arranged to contact a corresponding one of the semiconductor regions.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This patent application claims priority to and the benefit of U.S. Provisional Patent Application Serial No. 62 / 773,172, filed on November 29, 2018, U.S. Provisional Patent Application Serial No. 62 / 773,168, filed on November 29, 2018, U.S. Provisional Patent Application Serial No. 62 / 773,148, filed on November 29, 2018, and U.S. Provisional Patent Application Serial No. 62 / 654,198, filed on April 6, 2018, each of which is hereby incorporated by reference in its entirety. This patent application also claims priority to and the benefit of U.S. Provisional Patent Application Serial No. 16 / 376,802 (Agent Docket No. 131815-244461_P270, SunPower Reference No. S2040US), previously filed on April 5, 2019, and entitled “Local Metallization for Semiconductor Substrates using a Laser Beam,” which is hereby incorporated by reference in its entirety. Technical Field

[0003] Embodiments of the present disclosure are in the field of renewable energy or semiconductor processing, and particularly include metallization of semiconductor substrates using laser beams and the resulting structures. Background Art

[0004] Photovoltaic cells (often referred to as solar cells) are well-known devices for converting solar radiation directly into electrical energy. Generally speaking, solar cells are manufactured on semiconductor wafers or substrates using semiconductor processing techniques to form pn junctions near the surface of the substrate. Solar radiation that impinges on the substrate surface and enters the substrate forms electron and hole pairs in the bulk of the substrate. The electron and hole pairs migrate to p-doped and n-doped regions in the substrate, thereby generating a voltage difference between the doped regions. The doped regions are connected to conductive regions on the solar cell to direct current from the cell to an external circuit coupled thereto.

[0005] Electrical conversion efficiency is an important characteristic of solar cells because it is directly related to the ability of the solar cell to generate electricity; higher efficiency provides added value to the end customer; and, all other things being equal, higher efficiency also reduces the manufacturing cost per watt. Similarly, simplified manufacturing methods provide opportunities to reduce manufacturing costs by reducing the unit cost of production. Therefore, technologies that increase the efficiency of solar cells and technologies that simplify the manufacture of solar cells are generally needed. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figures 1A to 1F A side view illustrating operations in a method of manufacturing a string of solar cells.

[0007] Figure 2 An exemplary workflow for constructing a solar cell is shown.

[0008] Figure 3A and Figure 3B A side view illustrating operations in a method of manufacturing a string of solar cells.

[0009] Figure 4 A side view illustrating operations in a method of manufacturing a string of solar cells.

[0010] Figure 5 A side view of a multi-solar cell string is shown.

[0011] Figure 6 A side view showing the operation of a solar cell string.

[0012] Figure 7 A side view showing the operation of a solar cell string.

[0013] Fig. 8A and Figure 8B A side view illustrating operations in a method of manufacturing a string of solar cells.

[0014] Fig. 9 A side view of a multi-solar cell string is shown.

[0015] Fig. 10A and Fig. 10B A side view illustrating operations in a method of manufacturing a string of solar cells.

[0016] Fig.11 A side view showing a method of manufacturing a solar cell string.

[0017] Fig.12 A side view showing a method of manufacturing a solar cell string.

[0018] Fig.13 A plan view of a solar cell string.

[0019] FIG. 14A to FIG. 14D Cross-sectional views illustrating various operations in a method of fabricating a solar cell.

[0020] FIG. 15A to FIG. 15C A cross-sectional view of a solar cell is shown.

[0021] Fig.16 A cross-sectional view of a solar cell is shown.

[0022] FIG. 17A to FIG. 17EExemplary substrates manufactured using the methods, means or apparatus described herein are shown.

[0023] 18A to 18C A side view illustrating operations in a method of manufacturing a string of solar cells.

[0024] FIG. 19A to FIG. 19B A side view showing an exemplary interconnection of metal ribbons of a solar cell. DETAILED DESCRIPTION

[0025] The following detailed description is merely exemplary in nature and is not intended to limit the application and use of the embodiments or such embodiments. As used herein, the word "exemplary" means "used as an example, instance or illustration". Any embodiment described herein as exemplary is not necessarily preferred or advantageous over other embodiments. In addition, it is not intended to be bound by any express or implied theory presented in the aforementioned technical field, background technology, summary of the invention or the following detailed description.

[0026] References to the phrase "one embodiment" or "an embodiment" are not necessarily to the same embodiment. The particular features, structures, or characteristics may be combined in any suitable manner consistent with the present disclosure.

[0027] Terminology. The following paragraphs provide definitions and / or context for terms found in this disclosure (including the appended claims):

[0028] "Area" or "portion" describes a discrete area, volume, portion, or location of an object or material that has definable characteristics but not necessarily fixed boundaries.

[0029] “Comprising” is an open term and does not exclude other structures or steps.

[0030] "Configured to" refers to a structure by indicating a device, such as a unit or component, including a structure that performs one or more tasks during operation, and such structure is configured to perform the tasks even if the device is not currently operating (e.g., not turned on / activated). A device "configured to" perform one or more tasks is expressly intended not to invoke the method or step-by-step interpretation of 35 U.S.C. §112(f) or the sixth paragraph.

[0031] The terms "first", "second", etc. are used as labels for the nouns that follow them, and do not imply any type of order (e.g., spatial, temporal, logical, etc.). For example, referring to a "first" solar cell does not necessarily mean that such solar cell is the first solar cell in a sequence; rather, the term "first" is used to distinguish the solar cell from another solar cell (e.g., a "second" solar cell).

[0032] “Coupled” means that, unless expressly stated otherwise, an element, feature, structure, or node is or can be directly or indirectly connected or communicated with another element / node / feature, and not necessarily directly mechanically connected together.

[0033] "Prevent" means to reduce, diminish, minimize, or effectively or physically eliminate something, such as to completely avoid an outcome, consequence, or future state.

[0034] "Exposure to a laser beam" describes the process of subjecting a material to an incident laser treatment and is used interchangeably with "subjected to laser," "laser treated," and other similar phrases.

[0035] "Doped regions," "semiconductor regions," and similar terms describe semiconductor regions disposed in, on, over, or above a substrate. Such regions may have N-type conductivity or P-type conductivity, and the doping concentration may vary. Such regions may refer to multiple regions, such as a first doped region, a second doped region, a first semiconductor region, a second semiconductor region, and the like. These regions may be formed of polysilicon on the substrate or as part of the substrate itself.

[0036] "Thin dielectric layer," "tunneling dielectric layer," "dielectric layer," "thin dielectric material," or intermediate layer / material refers to a material on a semiconductor region between a substrate and another semiconductor layer, or between doped regions or semiconductor regions on or in a substrate. In certain embodiments, the thin dielectric layer may be a tunneling oxide or nitride layer having a thickness of about 2 nanometers or less. A thin dielectric layer may refer to a very thin dielectric layer through which electrical conduction may be achieved. Conduction may be due to quantum tunneling and / or the presence of smaller regions that are directly physically connected through thin points in the dielectric layer. Exemplary materials include silicon oxide, silicon dioxide, silicon nitride, and other dielectric materials.

[0037] An "intermediate layer" or "insulating layer" describes a layer that provides electrical insulation, passivation, and suppresses light reflectivity. An intermediate layer may be several layers, such as an intermediate layer stack. In some contexts, an intermediate layer may be interchangeable with a tunneling dielectric layer, while in other contexts, an intermediate layer is a mask layer or an "anti-reflective coating" (ARC layer). Exemplary materials include silicon nitride, silicon oxynitride, silicon oxide (SiOx), silicon dioxide, aluminum oxide, amorphous silicon, polycrystalline silicon, molybdenum oxide, tungsten oxide, indium tin oxide, tin oxide, vanadium oxide, titanium oxide, silicon carbide, and other materials and combinations thereof. In a certain example, the intermediate layer may include a material that can be used as a moisture barrier. In addition, for example, the insulating material may be a passivation layer of a solar cell. In a certain example, the intermediate layer may be a dielectric bilayer, such as silicon oxide (SiOx) with a high hydrogen content. x ), aluminum oxide (Al2O3) dielectric double layer.

[0038] "Locally deposited metal" and "metal deposition" are used to describe the formation of a metal region by exposing a metal source to a laser that forms and / or deposits metal from the metal source onto a portion of a substrate. The process is not limited to any particular theory or mechanism of metal deposition. In a certain example, the locally deposited metal can be formed when a metal foil is exposed to a laser beam that forms and / or deposits metal from a metal foil (such as the entire metal foil exposed to the laser beam) onto a portion of a silicon substrate. The process may be referred to as "laser assisted metallization patterning" or LAMP technology. The locally deposited metal may have a thickness of 1 nanometer (nm) to 20 micrometers (μm), a width approximately defined by the laser beam size, and physical and electrical properties that match those of the source metal foil.

[0039] "Patterning" refers to a process that promotes separation or partial separation of source metal, and may specifically refer to weakening the area of ​​metal foil between the bulk of the metal foil and the deposited area of ​​the metal foil (i.e., deposited metal). This patterning may be the result of heating, perforating, deforming, or other manipulation of the metal foil by the same laser process LAMP that deposits the metal foil onto the substrate and may promote the removal of the bulk of the metal foil (i.e., undeposited metal foil) from the resulting device. References to LAMP include such patterning unless otherwise specified.

[0040] "Substrate" may refer to, but is not limited to, a semiconductor substrate such as silicon, and specifically, such as a monocrystalline silicon substrate, a polycrystalline silicon substrate, a wafer, a silicon wafer, and other semiconductor substrates for solar cells. In certain examples, such substrates may be used in microelectronic devices, photovoltaic cells or solar cells, diodes, photodiodes, printed circuit boards, and other devices. These terms are used interchangeably herein.

[0041] In addition, certain terms may be used in the following description for reference purposes only and are not intended to be limiting. For example, terms such as "upper," "lower," "above," and "below" refer to directions in the drawings for which reference is provided. Terms such as "front," "back," "rear," "side," "outside," and "inside" describe the orientation and / or position of portions of a component within a consistent but arbitrary reference system, which orientation and / or position can be clearly understood by reference to the text describing the component in question and the associated drawings. Such terms may include the words specifically mentioned above, their derivatives, and words of similar meaning.

[0042] Described herein is the use of a laser beam to string and locally metallize a semiconductor substrate and the resulting structure (e.g., a microelectronic device, a semiconductor substrate, a solar cell, a string of solar cells, and / or a solar cell array). In the following description, many specific details such as specific process flow operations are set forth in order to provide a thorough understanding of the embodiments of the present disclosure. It will be apparent to those skilled in the art that the embodiments of the present disclosure may be practiced without these specific details. In other cases, well-known manufacturing techniques, such as emitter region manufacturing techniques, are not described in detail to avoid unnecessarily obscuring the embodiments of the present disclosure. In addition, it should be understood that the embodiments shown in the figures are exemplary displays and are not necessarily drawn to scale.

[0043] The methods described herein may be applicable to interdigitated back contact (IBC) solar cells and other types of solar cells, including continuous emitter back contact solar cells, front and / or back contact solar cells with trench architecture (e.g., n-type doped regions and p-type doped regions separated by trench structure films), heterojunction solar cells with intrinsic thin layers (HIT), tunneling oxide passivation contact (TOPCon) solar cells, organic front contact solar cells, front contact cells with overlapping cell portions, passivated emitter and rear cell (PERC) solar cells, mono-PERC solar cells, passivated emitter rear local diffusion (PERL) cells, 3-terminal or 4-terminal tandem cells, stacks, and other types of solar cells. The metallization methods described herein may be applicable to solar cells having a plurality of subcells coupled by a metallization structure. In certain embodiments, the grooves may be positioned between adjacent subcells, and the metallization structure may connect adjacent subcells together. In certain embodiments, the grooves may divide and physically separate one subcell from another subcell (e.g., an adjacent subcell). In certain embodiments, the metallization structure may physically and electrically connect the subcells, wherein the metallization structure may be positioned above the grooves.

[0044] The metallization methods described herein can also be applied to solar cells and / or solar cell portions that have been segmented and / or physically separated (e.g., sliced, partially sliced ​​and further separated). In a certain example, these solar cells and / or solar cell portions can be physically connected and / or electrically connected together by the metallization structures and processes described herein.

[0045] The metallization methods described herein may also be generally applicable to microelectronic devices, semiconductor devices and other substrates, such as light emitting diodes, micro-electromechanical systems, etc. The embodiments described herein may be distinguished from laser induced forward transfer (LIFT) methods, in which thin films are deposited on glass and require subsequent operations such as electroplating to achieve the desired metal thickness.

[0046] A string of solar cells (such as two or more solar cells using metal foil and LAMP deposition) and methods of making the same are disclosed herein. Two or more solar cells can be connected using inexpensive metal foil in a single operation, providing a significant cost advantage over competing technologies.

[0047] In one example, two solar cells are electrically connected by positioning a metal foil over the back side of a first solar cell, and performing a LAMP technique treatment on the metal foil in one or more locations on the back side of the first solar cell. The metal foil may also be positioned over the front side of the first solar cell, and then the LAMP technique treatment is performed in one or more locations on the front side of the first solar cell. The LAMP technique forms one or more conductive contact structures that electrically connect the metal foil to the respective front and back sides of the first solar cell. The conductive contact structures include locally deposited metal portions that electrically connect a metal source (e.g., a metal foil) to a semiconductor region of the solar cell.

[0048] The first solar cell can be connected to the second solar cell via a metal foil on the front or back side of the first solar cell, wherein such metal foil or a portion thereof is positioned over a portion of the second solar cell, and a conductive contact structure is formed between such metal foil and the second solar cell by bonding or LAMP technology. Exemplary bonding techniques include the use of a conductive adhesive, welding or soldering. The conductive contact structure includes locally deposited metal portions that electrically connect a metal source (e.g., the above-mentioned metal foil) to the semiconductor region of the solar cell.

[0049] Depending on the type of solar cells to be connected (e.g., front-contact or back-contact solar cells), the front side of the first solar cell can be connected to the front side of the second solar cell or the back side of the second solar cell. By repeating such a process, a string of solar cells of almost any length can be formed (e.g., by connecting a third solar cell, a fourth solar cell, a fifth solar cell, etc. to the first solar cell or the second solar cell). These longer strings of solar cells can be connected together to form a solar cell array, for example in series and / or in parallel, such as with interconnects and / or bus bars. The first solar cell and / or the second solar cell may include one or more contact pads, and the conductive contact structure may electrically connect the metal foil to the one or more contact pads.

[0050] Strings of solar cells may also be connected together by stacking the strings of solar cells together, for example with their front faces facing each other, and then bonding (electrically and physically bonding) a metal foil extending from one solar cell at the end of a first string of solar cells to a complementary metal foil extending from a solar cell at the end of a second string of solar cells, the second string of solar cells stacked on top of the first string of solar cells to form an electrical connection, for example, using metal foils extending from the ends of the first string of solar cells and the second string of solar cells to achieve electrical connection. Bonding may be accomplished by the LAMP techniques described herein, welding processes such as laser welding, induction welding, ultrasonic welding, plasma welding, and resistance welding, or thermocompression bonding. In another example, bonding is achieved by a conductive adhesive or by crimping a foil extending from one solar cell to a foil extending from another solar cell.

[0051] A positioning process may be performed to position or fix the metal foil to the substrate, such as using a vacuum and / or bonding process to fix the metal foil on / on the substrate. The positioning process may include hot pressing, where rollers and / or heat are used to position or fix the metal foil on the substrate. A vacuum process, hot pressing process, or other similar processes may also be used to uniformly position the metal foil and inhibit the formation of air gaps or air pockets between the metal foil and the substrate.

[0052] The insulating material may be used to electrically isolate a portion of the foil from the first solar cell and / or the second solar cell (such as a selected side or edge of the first solar cell and / or the second solar cell). In a certain example, the insulating material is positioned over at least a portion of the back side of the metal foil (e.g., the side of the metal foil facing away from the back side of the first solar cell). In another example, the insulating material may be positioned over at least a portion of the front side of the metal foil (e.g., the side of the metal foil facing the back side of the first solar cell). The position of the insulating material may be selected so that when the two solar cells are connected and / or mounted, the insulating material inhibits short circuits between the solar cell and the metal foil. The insulating material may be applied before or after the LAMP technique and may cover the entire bulk metal foil or be selectively patterned to provide selective insulation.

[0053] The insulating material can be any non-conductive material, such as a non-conductive tape or other suitable non-conductive shield or covering, and can be used to cover the metal foil when viewed from above. The non-conductive shield can cover the exposed portion of the metal foil between the solar cells. In a certain example, the non-conductive shield can cover the visible portion in the final product, such as a solar cell stack, a module panel, etc. Therefore, the insulating material can include a substantially opaque material that is sufficient to shield the metal foil when viewed from the front. The insulating material can also help to arrange the solar cells and / or fix the solar cells together. Examples of insulating materials include polypropylene or polyethylene, which can further include an adhesive layer such as acrylate. Encapsulating materials can also be used as insulating materials. Exemplary encapsulants include one of the same materials used to form a solar module from the solar cells described herein, including but not limited to polyolefins, EVA, PVA and PVB encapsulants.

[0054] Although insulating materials may be beneficial for the reasons described above, other embodiments may not include insulating materials. In some embodiments, metal foils are provided between solar cells for self-lapping solar cell strings. These designs may facilitate packaging, unpacking, assembly, connection, installation, and maintenance of solar cell modules. These modules may include single solar cell arrays as well as multiple solar cell arrays. Including insulating materials may facilitate lapping when solar cells overlap, for example, adjacent solar cells, thereby preventing short circuits between the solar cells and the metal foil.

[0055] In one embodiment, for example, a metal foil located between a first solar cell and a second solar cell is folded or bent to facilitate connecting the foil to the back side of one solar cell and the front side of another solar cell. The bending can be performed before or after connecting the solar cells. Furthermore, the connection of the first solar cell and the second solar cell to the metal foil can be completed in any order, or even substantially simultaneously. For example, the back side of the first solar cell can be connected to the metal foil before the front side or the back side of the second solar cell is connected to the metal foil. Conversely, the back side of the first solar cell can be connected to the metal foil after the front side or the back side of the second solar cell is connected to the metal foil.

[0056] In one example, the power, wavelength, and / or pulse duration of the laser used in the LAMP technique is selected to form a plurality of locally deposited metal portions without completely ablating the foil. The power, wavelength, and / or pulse duration may be selected / adjusted based on the metal foil composition, melting temperature, and / or thickness. In one example, the laser has a wavelength between about 250 nm and about 2000 nm (such as 250 nm to 300 nm, 275 nm to 400 nm, 300 nm to 500 nm, 400 nm to 750 nm, 500 nm to 1000 nm, 750 nm to 1500 nm, or 1000 nm to 2000 nm), and the laser peak power is greater than 5×10 +4 W / mm 2 , and the laser is a pulsed laser having a pulse frequency of about 1 kHz and about 10 MHz (such as about 1 kHz and about 10 MHz, such as 1 kHz to 1000 kHz, 500 kHz to 2000 kHz, 1000 kHz to 5000 kHz, 2000 kHz to 7500 kHz or 5000 kHz to 10 mHz). The pulse duration may be between 1 fs and 1 ms (such as 1 fs to 250 fs, 100 fs to 500 fs, 250 fs to 750 fs, 500 fs to 1 ns, 750 fs to 100 ns, 1 ns to 250 ns, 100 ns to 500 ns, 250 ns to 750 ns, 500 ns to 1000 ns, 750 ns to 1500 ns, 1000 ns to 5000 ns, 1500 ns to 10000 ns, 5000 ns to 100000 ns, 10000 ns to 500000 ns, or 100000 ns to 1 ms). The laser may be an infrared, green, or ultraviolet laser. In some instances, the laser beam has a width between about 20 and about 50 μm (such as 20 to 30 μm, 25 to 40 μm, and 30 to 50 μm).

[0057] In one embodiment, a method of manufacturing a solar cell string includes forming a semiconductor region in or on a substrate. In another embodiment, the substrate is provided with a semiconductor region in or on the substrate. An intermediate layer may be formed on the semiconductor region, the intermediate layer having openings that expose portions of the semiconductor region. A metal foil may be positioned above the intermediate layer and exposed to a laser beam in a position above, above a portion of, offset from, or adjacent to the openings in the intermediate layer. The metal foil is exposed to the laser beam to form a plurality of conductive contact structures electrically connected to the semiconductor region, each conductive contact structure comprising a locally deposited metal portion. In an embodiment, the method may include laser sputtering a metal foil in a position above the opening in the intermediate layer. Laser sputtering may form a plurality of conductive contact structures electrically connected to the semiconductor region.

[0058] Without being bound by theory, the above-described localized metal deposition achieved by exposing the metal foil to a laser beam can be achieved by partially or completely melting the laser-irradiated portion of the metal foil, partially or completely ablating a portion of the metal foil and subsequently redepositing onto the wafer surface, and / or laser sputtering portions of the metal foil during laser deposition and patterning of the metal foil. In a certain example, first portions of the metal foil are exposed to a laser beam and subsequently deposited onto the wafer surface while the source metal foil layer is patterned. In addition, certain embodiments result in these first portions of the metal foil being fully or at least partially connected to adjacent second portions of the metal foil that have not been exposed to laser irradiation. The metal foil region between the first portion and the second portion may have a relatively weak physical structure (compared to the second portion) that promotes separation of the second portion from the first portion, thereby forming a discrete conductive path.

[0059] Conventional metal deposition and patterning of metal layers for solar cells may include metal deposition using a vacuum chamber or metal plating using a chemical bath. One or more patterning operations are also typically performed to determine areas where deposited metal needs to be removed. In contrast, the metallization method disclosed herein effectively achieves metal deposition and patterning in a single process operation without the need for previously required processes. However, in addition to conventional metal deposition (e.g., after it), LAMP technology may also be used.

[0060] Several implementations described herein can provide lower cost and faster metallization (and eliminate the associated etching process) than using optical lithography, and can achieve more precise patterning with smaller feature width and higher aspect ratio than screen printing. LAMP technology can deposit and pattern metal directly on a substrate using inexpensive metal foil via laser in a single operation, which has a significant cost advantage over competing technologies. LAMP technology can also manufacture relatively small features. Specifically, compared with the structure usually formed using screen printing, tighter spacing and higher efficiency can be achieved. In a certain example, the screen printing conductive contact can include a silver paste with a thickness of up to 50 microns and a minimum feature size of 50 microns. In contrast, LAMP technology can produce a thickness of about 1 nanometer to 20 microns and a minimum feature size of about 25 microns. The deposition thickness can be controlled by the starting thickness of the source material and the laser conditions. The deposition thickness can be in the range of about 5% to about 25% of the thickness of the source material. The thickness of the source material partially limits the laser conditions (especially the pulse duration) required for LAMP. The thickness of the source material partially limits the laser conditions (especially the pulse duration) required for LAMP. In one embodiment, the metal source material may have a thickness in the range of about 1 nm to 1 μm. In a certain example, performing a laser assisted metallization process (LAMP) may include sputtering a metal from a thin source material onto a thin polymer or film using a picosecond laser or a femtosecond laser, wherein the thin source material may have a thickness in the range of about 1 nm to 1 μm. In a certain embodiment, the metal source material may have a thickness in the range of 1 μm to 100 μm (such as 1 μm to 10 μm, 5 μm to 25 μm, 10 μm to 50 μm, 25 μm to 75 μm, or 50 μm to 100 μm). In a certain example, performing a laser assisted metallization process (LAMP) may include sputtering a metal from a metal foil onto a substrate using a picosecond laser or a femtosecond laser, wherein the metal foil may have a thickness in the range of about 1 μm to 100 μm. In various implementations of the LAMP technology, metal thickness parameters before and after LAMP are disclosed, as described in Table 1.

[0061] Table 1

[0062]

[0063] Other advantages include providing a viable method to use lower cost aluminum (in the form of aluminum foil) instead of silver to achieve metallization of semiconductor features. In addition, the aluminum deposited using the LAMP technique can be a pure bulk metal, compared to screen printed silver which has a higher resistance due to its porosity. In various examples using aluminum as the metal foil, in addition to the examples shown in Table 1, the solar cell can have a layer (or layers) of aluminum with a thickness of about 1 nm to 500 μm. The metal foil can include an aluminum content greater than about 97% and a silicon content in the range of about 0 to 2%.

[0064] Exemplary aluminum (Al) metal foils have a thickness approximately in the range of 1 to 100 μm (e.g., in the range of 1 to 15 μm, 5 to 30 μm, 15 to 40 μm, 25 to 50 μm, 30 to 75 μm, or 50 to 100 μm). The Al metal foil may be a tempered grade metal foil, such as, but not limited to, grade F (free state), grade O (fully soft), grade H (strain hardened), or grade T (heat treated). The aluminum metal foil may or may not be anodized, and may include one or more coatings. Multilayer metal foils may also be used. Exemplary metal foils include metal foils of aluminum, copper, tin, tungsten, manganese, silicon, magnesium, zinc, lithium, and combinations thereof, with or without aluminum or as an alloy in the laminate.

[0065] In another example, the operation of forming a metal and patterning a metal layer for a semiconductor device (e.g., a solar cell) may include: first forming a first metal layer on a substrate (e.g., a metal seed layer) by conventional techniques or LAMP techniques; positioning a second metal layer (such as aluminum foil) on the first metal layer; and bonding a portion of the first metal layer to the second metal layer (e.g., using a laser). The metal seed layer may include a deposited tin, tungsten, titanium, copper, and / or aluminum layer. A sputtering process may be used to deposit the metal seed layer. The metal seed layer may have a thickness in the range of 0.05 to 50 microns.

[0066] The solar cell may include a patterned backplane, an encapsulant, and / or a colored (tinted) back encapsulant. The metal foil may be hidden using a mask or covering material (such as a tape) placed between the edge of the solar cell and the metal foil, in the gap region between adjacent solar cells (across the gap between the two). The metal foil may also be anodized or otherwise colored to match the solar cell so that the metal foil is not easily visible or distinguishable from the solar cell when viewed from the front (i.e., the metal foil is covered or obscured). The metal foil may also include an adhesive, such as adhering the metal foil to a substrate for pre-LAMP processing and / or post-LAMP processing. Optionally or in addition, the substrate includes an adhesive to fix the metal foil for pre-LAMP processing and / or post-LAMP processing. A dielectric material, such as a damage buffer material (DBM) or an oxide material, may also be placed between the substrate and the metal foil.

[0067] After the deposition and patterning process as described above, the residues of the metal layer source can be removed in the subsequent process. For example, the portion of the metal foil not exposed to the laser beam is removed (i.e., the undeposited metal foil is removed). In one such embodiment, removing at least a portion of the metal foil not exposed to the laser beam may include removing all portions of the metal foil not exposed to the laser beam. In another example, a portion of the metal foil is exposed to a subsequently applied laser beam (such as another laser beam) and / or is exposed to a laser with different characteristics (e.g., power, frequency, etc.). This subsequent treatment can provide further patterning of the metal foil to achieve the purpose of removing the undeposited metal foil. In some embodiments, the LAMP technology is repeatedly applied on the substrate in continuous steps to form a metal layer on the substrate. In particular, the first foil is processed by the first LAMP technology to form a first conductive contact structure on a first portion or region of the substrate, and the second foil is processed by the second LAMP technology on a second portion or region of the substrate. The second LAMP technology can be used after the portion of the first foil that has not been processed by the first LAMP technology is removed, and the second portion or region can be positioned on the substrate to remove these portions of the first foil. Likewise, the portion of the second foil not treated by the second LAMP technique may be removed, and similar third LAMP, fourth LAMP, etc. techniques may be performed successively to form a metal layer on the substrate. This embodiment may be used in instances where the portion of the foil to be removed is difficult to remove due to its shape or proximity to other features on the substrate, such as metal features.

[0068] In a certain example, the non-local deposition portion of the metal foil is removed, which may cause the local deposition portion of the metal foil to have edge features, such as edge features formed by physically separating, destroying or tearing the bulk metal foil that has not been treated with the LAMP technology from the metal foil portion deposited on the substrate. The edge features may include torn edges or sharp torn edges. In a certain example, the first part of the metal (in this example, aluminum foil) is deposited or directly fixed to the surface of the solar cell by the LAMP technology, while the second part of the metal (adjacent to the first part) is not processed by the LAMP technology and is not deposited or directly fixed to the surface of the solar cell. The first and second parts of the metal foil are attached to each other, and the area between them can be patterned to weaken the area, preferably using the same LAMP technology in the same process step as the deposition of the first part. The second part is removed and physically separated or torn from the first part, thereby forming an edge structure along the side of the first part. The edge structure or feature may be sharp and / or torn in appearance, and is different from the rounded or curved edge of the metallized feature, which is left by metal welding, brazing, electroplating or otherwise deposited on the substrate. Edge structures can also be polished to remove sharp or rough features in subsequent steps.

[0069] Exposing the foil to a laser beam may also form other unique features compared to conventional metallization methods, including the formation of a "U-shaped" structure or valley where the laser beam has contacted the foil. The width of the "U-shape" is approximately equal to the width of the laser beam used. In a certain embodiment, the conductive contact structure is at least temporarily connected by extending from the conductive contact structure to the edge portion of the area of ​​the metal foil not exposed to the laser beam until the area not exposed to the laser beam is removed.

[0070] In one example, the metal foil is exposed to the laser beam to form spatter or sputtering features on the solar cell (e.g., on the foil and / or substrate). Such spatter features can be used to determine whether the solar cell is formed using the LAMP technology. In some examples, at least the spatter features of the metal foil can be removed, for example to facilitate the bonding of a second material to the foil, such as a support plate for removing the foil that has not been exposed to the laser beam, or other components of the solar cell, solar cell string, or higher-level structure, such as an interconnection piece where the foil extends from another cell, or other electrically connected or non-electrically connected components of the solar cell, solar cell string, or higher-level structure. Such spatter can be removed by polishing or etching.

[0071] Laser-assisted metallization can be repeated to build a multi-layer metal foil structure to achieve the purpose of increasing metal thickness (for example, for conductivity or structural purposes) and to facilitate the removal of undeposited portions of the first metal foil layer. Specifically, a second metal source (such as a metal foil, wire, or tape) can be positioned above the first metal foil, wherein the second metal source is laser beam treated in selected locations above the locations of the first metal foil that are not locally deposited (i.e., directly electrically connected) to the semiconductor region, thereby welding or bonding the second metal source to the first metal foil. The second metal source is then mechanically removed to selectively remove areas of the first metal foil that are not locally deposited to the semiconductor region on the substrate.

[0072] In addition, the second metal source is used to provide additional metallization thickness to all or part of the solar cell, such as for the construction of busbars, where the additional metal thickness facilitates electrical conduction. The second metal source can be bonded to the first metal foil via a laser at locations not locally deposited in the first metal foil and / or at selected locations on the same or approximately the same orientation as the first metal foil locally deposited to the semiconductor region. This process can limit the interconnection area between adjacent solar cells and can also be applied to adjacent solar cell strings.

[0073] In addition, the second metal source is positioned on the solar cell substrate, which includes a locally metallized area or portion, such as an area or portion formed by a first metal foil or by a conventional metallization technique. The second metal source is bonded to the locally metallized sites in the selected areas to provide additional metallization in these selected areas. In a certain example, the second metal source is patterned to increase the metal thickness in certain areas and used as a support plate to remove non-locally deposited portions of the first metal foil in other areas. The second metal source can be bonded to the first metal foil using a bonding process. The splicing process includes forming a spot welding array, which can be performed using a laser, hot press bonding (e.g., using nail teeth, nail tooth rollers, needle rollers or nail beds) or conventional brazing and welding techniques. The second metal source can also be bonded to the first foil using a conductive adhesive. In another embodiment, the carrier is a plastic, polymer and / or film, which can be used as an insulator, a moisture barrier, a protective layer, etc.

[0074] In an embodiment, the substrate may have a plurality of doped regions. In an embodiment, the plurality of doped regions may be referred to as a first doped region, a second doped region, etc. In an example, the first doped region may include an N-type semiconductor region, and the second doped region may include a P-type semiconductor region. In an example, the substrate may include a plurality of N-type and P-type semiconductor regions. In some embodiments, the N-type and P-type semiconductor regions may be alternating N-type and P-type semiconductor regions. In an embodiment, the alternating N-type and P-type semiconductor regions may be placed one by one or repeatedly, for example, in an interdigitated structure.

[0075] In an embodiment, the method described herein may include forming a plurality of N-type and P-type semiconductor regions in or on a substrate. Additionally, in a certain example, a method of manufacturing a solar cell may include forming a plurality of N-type or P-type semiconductor regions in or on a side of a substrate. In a certain embodiment, the method may include placing the N-type and P-type semiconductor regions on the front side, the back side, or both of the substrate.

[0076] Strings of solar cells are disclosed herein, such as two or more strings of solar cells. The solar cell may include a doped region, such as a doped region disposed in a substrate, above a substrate, on a substrate, or a combination thereof. In certain embodiments, the doped region may have an N-type conductivity type or a P-type conductivity type. In certain embodiments, the doped region may be positioned on the front side, the back side, or a combination thereof of the substrate.

[0077] In an embodiment, a metal foil is disposed on the back side, the front side, or both the back side and the front side of each of the plurality of solar cells. The metal foil extends between the solar cells, effectively spanning the gap or space between the solar cells. In an example, the back side of the solar cell is electrically connected to the front side of another solar cell through the metal foil. In an example, the back side of the solar cell is electrically connected to the back side of another solar cell through the metal foil. In an example, the front side of the solar cell is electrically connected to the front side of another solar cell through the metal foil. In an embodiment, the solar cell string includes one or more laser assisted metallization conductive contact structures that electrically connect the metal foil to the solar cell. In an embodiment, each conductive contact structure includes a locally deposited metal portion.

[0078] The solar cell may include a contact pad to facilitate the laser assisted metallization conductive contact structure to electrically connect the metal foil, one or more additional solar cells, bus bars and / or solar cell interconnects. In a certain embodiment, the solar cell string includes a third solar cell, a fourth solar cell, a fifth solar cell, etc. connected to the first solar cell and / or the second solar cell. In a certain embodiment, the metal foil is folded or bent between the first solar cell and the second solar cell. The folded or bent metal foil can be used as a stress relief feature.

[0079] The solar cell string may include insulating material as described above, which may be used to electrically isolate portions of the foil from the first solar cell and / or the second solar cell, such as selected sides or edges of the first solar cell and / or the second solar cell.

[0080] In certain embodiments, the metal foil may include different pattern configurations. For example, the metal foil may extend between the first solar cell and the second solar cell and may include stress relief features. In other examples, the metal foil may include information (such as a QR code for solar cells and / or cell string level tracking, alignment, etc.). In one embodiment, the metal foil may include a pattern (such as an interdigitated pattern, a fishbone pattern, etc.). In one embodiment, the metal foil may include a texture (such as a corrugation or a pre-existing texture for unidirectional strength).

[0081] In certain embodiments, the metal foil includes a laser metallized workpiece as described above, such as edge features and / or spatter features.

[0082] As an example of a solar cell string, Figures 1A to 1F A side view of an operation in a method of manufacturing a solar cell string is shown. It will be apparent that the manufacture of solar cell strings can be extended to multiple solar cell strings (see, e.g. Figure 5 , 9 as well as FIG. 10A to FIG. 13 and Figure 18 to Fig.19B ). In addition, it is contemplated that one or more multiple solar cell strings may be further coupled together to form a solar cell array, such as by attaching bus bars or other interconnects at the ends of the strings in parallel and / or series arrangements.

[0083] See also Figure 1A , a solar cell 125 is provided. The solar cell 125 can have any size or configuration. The solar cell 125 includes a plurality of conductive contact structures 110 that are electrically connected to a plurality of semiconductor regions in or on the substrate 100. The conductive contact structures 110 can be formed conventionally, or using a method as disclosed herein and as described herein. FIG. 14A to FIG. 14D The metal foil 120 is formed by a laser deposition process of the metal foil shown. A metal such as metal foil 120 is further provided. The solar cell 125 can be a front contact solar cell and / or a back contact (e.g., interdigitated back contact) solar cell. In a certain example, for a back contact solar cell, the conductive contact structure 110 does not need to be formed.

[0084] See also Figure 1B , positioning the metal foil 120 on the back side 131 of the solar cell 125, and as Figure 1C As shown, a metal foil 120 is exposed to a laser beam 108 of the LAMP technique in a position above the back side 131 of a solar cell 125. The metal foil 120 is exposed to the laser beam 108 to form a plurality of conductive contact structures electrically connected to the back side 131 of the substrate 100. The conductive contact structures electrically connect areas of the substrate 100 to the metal foil 120, allowing electrons to flow from the substrate 100 to the metal foil 120. The conductive contact structures may be distributed uniformly, in a certain pattern, randomly, or in other ways on the back side 131 of the substrate 100. Depending on the polarity of the connection, the metal foil 120 may conduct current to or from the substrate 100. The metal foil 120 is an exemplary metal source and is referred to as a local source because the metal foil 120 is first placed on the substrate surface and then exposed to the laser process (i.e., the LAMP technique) to deposit metal from the metal foil 120 (metal source) onto portions of the substrate 100.

[0085] Portions of the metal foil are fully or at least partially connected to adjacent portions of the metal foil that have not been laser irradiated. In addition to forming an electrical connection between the metal foil 120 and the substrate 100 in the vertical direction, the metal foil can provide bulk conductivity across the entire horizontal plane of the back side of the substrate 100 to provide a continuous conductive surface on the back side of the substrate 100. In addition, the metal foil 120 is used for local metal deposition and / or patterning, such as similar to reference FIG. 14A to FIG. 14DAs described above, portions of the metal foil 120 may be removed (e.g., if the back side of the substrate 100 is used to collect light, like a bifacial solar cell). The solar cell 125 including the electrically attached metal foil 120 may be used to further fabricate a solar cell string, wherein a portion of the metal foil 120 extends beyond the edge of the substrate 100.

[0086] See also Figure 1D The metal foil 120 is electrically connected to the back side 131 of the substrate 100, and the metal foil 120 can be manipulated (such as bent or folded) so that the end of the metal foil 120 protruding from the end of the solar cell 125 can be positioned over the metallized portion of the front side 132 of the adjacent solar cell. The metal foil 120 can be a continuous sheet or a series of strips in a ribbon shape.

[0087] See also Figure 1E , two (or more, such as Figure 5 The solar cells are positioned adjacent to each other so that the metal foil 120 protruding from the first or left solar cell 125a extends over the metallized portion of the second or right solar cell 125b. The metal foil 120 extends from left to right with a length sufficient to conduct electricity between the solar cells 125a and 125b, and can be minimized in this regard. In another embodiment, the metal foil 120 extends from left to right with a length sufficient to cover the entire front side 132 of the solar cell 125b. Therefore, the same piece of metal foil 120 can be used to form conductive contact structures on both the back side 131 of the solar cell 125a and the front side 132 of the solar cell 125b, which can be completed in one or continuous applications of the LAMP, and it can include patterning and removal of non-locally deposited metals on the back side 131 and / or the front side 132.

[0088] See also Figure 1F , a conductive bonding portion 115 is formed in a position above the conductive contact structure 110 of the solar cell 125b to electrically connect the metal foil 120 to the conductive contact structure 110 of the solar cell 125b. The conductive bonding portion 115 electrically connects the conductive contact structure 110 to the metal foil 120, allowing electrons to flow. One or more conductive bonding portions 115 may be distributed on the metal foil 120 uniformly, in a certain pattern, randomly, or in other ways. The metal foil 120 may be exposed to a laser beam to form a plurality of conductive contact structures that electrically connect the metal foil 120 to the conductive contact structure 110 of the solar cell 125b, thereby obtaining a welded or other electrically bonded structure. Alternatively, other bonding mechanisms may be used to connect the metal foil 120 to an existing conductive contact structure 110. Repeatable Figures 1A to 1F The method and structure shown in the figure form a solar cell string by a plurality of solar cells 125, such as Figure 5 shown.

[0089] Figures 1A to 1F The process steps shown may be performed in a single operation or in a different order than shown. Other steps may also be performed, such as performing Figure 1C The process shown, but in Figure 1F In the process shown, soldering, welding or adhesion to 125 by adhesive 120 is used. In one example, a bonding process can be performed to bond the metal foil 120 to the conductive contact structure 110 of the solar cell 125b. In another example, the bonding process can include the laser process described herein. The bonding can include a welding process, such as described above. The bonding can also be thermocompression bonding, soldering or using a conductive adhesive. In addition, multiple solar cell strings can be coupled together to form a solar cell array, for example by attaching bus bars at the ends of the cell strings in parallel and / or series arrangement. Again refer to Figures 1A to 1F The process may be repeated with successive foils to form conductive contact structures on different portions of the substrate, such as a second portion or region, a third portion or region, etc. of the substrate, where each portion or region is a discrete area on the substrate.

[0090] Figure 22100 is a flowchart representing various operations in a method of manufacturing a solar cell according to an embodiment of the present disclosure. At operation 2104, the method includes providing a first solar cell. At operation 2106, the method includes positioning a metal foil over a portion of the first solar cell. At operation 2108, the method includes exposing the metal foil to a laser beam, wherein exposing the metal foil to the laser beam forms a plurality of conductive contact structures electrically connected to the first solar cell. At operation 2110, the method includes providing a second solar cell. At operation 2112, the method includes positioning the metal foil over a portion of the second solar cell. At operation 2114, the method may include bonding the metal foil to the second solar cell. In certain embodiments, at operation 2114, bonding may include exposing the metal foil to a laser beam, wherein exposing the metal foil to the laser beam forms a plurality of conductive contact structures electrically connected to the second solar cell. In certain embodiments, bonding may include a welding process, such as laser welding or induction welding. In embodiments, bonding is performed by a thermocompression bonding process. In certain embodiments, bonding is accomplished by a conductive adhesive. At optional operation 2116, the method may include connecting a string of solar cells (e.g., at the ends of the string of cells) to a foil, bus bar, and / or threaded metal foil ribbon extending from a substrate, in some instances, treated with the LAMP technology described herein. In other instances, the foils of the corresponding strings of solar cells may be bonded together, for example, by welding, brazing, hot pressing, or by a conductive adhesive. Optionally or additionally, the method includes removing at least a portion of the metal foil that was not exposed to the laser beam. Optionally or additionally, the method includes removing spatter features of the metal foil that was not exposed to the laser beam. Optionally or additionally, the method includes forming a plurality of semiconductor regions in or on the substrate. The above operations may be repeated, for example with a continuous foil.

[0091] As another example, FIG. 3A to FIG. 3B A side view showing the fabrication of a solar cell string.

[0092] See also Figure 3A , a solar cell 125a is provided. The solar cell 125a may have any size or configuration, and does not include or necessarily include back metallization. In one embodiment, the solar cell 125a is made by the method described herein (e.g., LAMP technology) and is FIG. 14A to FIG. 14D As shown. Solar cell 125a includes a plurality of conductive contact structures 110, which are electrically connected to a plurality of semiconductor regions in or on substrate 100. In one embodiment, the semiconductor regions may include N-type and / or P-type semiconductor regions in or on substrate 100. Conductive contact structures 110 may be formed conventionally or using a laser deposition process of a metal foil as disclosed herein. Figures 1A to 1FUnlike the example shown, in this example, a second solar cell 125b is provided before the metal foil is connected to the first solar cell 125a. Therefore, a first metal foil 120a is further provided. The metal foil 120a may be pre-folded, such as Figure 3A As shown, or it can be unfolded. Foil 120a can be adhered to first solar cell 125a via vacuum, heat treatment, etc. Alignment methods can be used to align 120a with 125b. Similarly, a second metal foil 120b can be provided and can be adhered to second solar cell 125b via vacuum, heat treatment, etc.

[0093] See also Figure 3B , the metal foil 120a may be positioned over the back side 131 of the solar cell 125a and over the edge portion of the front side 132 of the second adjacent solar cell 125b. The two solar cells 125a and 125b may be positioned adjacent to each other so that the metal foil 120a is below the substrate 100 of the first solar cell 125a and extends over the metallization portion of the solar cell 125b (e.g., as shown), or alternatively, extends directly over the solar cell 125b. A conductive bond 115 is formed in a position over the conductive contact structure 110 of the solar cell 125b to electrically connect the metal foil 120a to the conductive contact structure 110 of the solar cell 125b. The conductive bond 115 electrically connects the conductive contact structure 110 to the metal foil 120a, allowing electrons to flow. One or more conductive bonds 115 may be distributed evenly, in a certain pattern, or otherwise on the metal foil 120a. In one embodiment, the metal foil 120a is exposed to a laser beam at 108 to form a plurality of conductive contact structures that electrically connect the metal foil 120a to the conductive contact structures 110 of the solar cell 125b. The conductive contact structures electrically connect the conductive contact structures 110 to the metal foil 120a, allowing electrons to flow. The conductive contact structures may be distributed uniformly, in a pattern, randomly, or in other ways on the metal foil 120a.

[0094] In one exemplary embodiment, solar cells 125a and 125b are provided, which have conventional metallization patterns (such as metal ink, metal paste and metal wire or aluminum, silver, copper, etc.) as the front electrode on the front side 132, and no back electrode on the back side 131. In this example, a metal foil (e.g., metal foil 120b for solar cell 125b) is used as the back electrode of solar cells 125a and 125b, wherein on the back side 131 of solar cells 125a and 125b, there is no intermediate metal structure between the metal foil and one or more semiconductor regions. Depending on the polarity of the connection, the metal foil 120a can conduct current to or from the solar cell 125b. In addition, different procedures and steps can be performed to form the solar cell string shown. For example, an automatic or manual alignment method can be used to position one solar cell adjacent to another solar cell. In addition, in one example, the steps of the laser deposition process are performed on the front side, the back side, or both the front side and the back side of a plurality of solar cells. Although as shown, the solar cells in the string of solar cells can be connected in series, the solar cells in the solar cell string can also be connected in parallel or in series and in parallel at the same time.

[0095] As another example, Figure 4 A side view of manufacturing a solar cell string is shown. A solar cell 125a is provided, which does not include a plurality of conductive contact structures electrically connected to a plurality of semiconductor regions in or on the substrate 100a. A second solar cell 125b is also provided, which does not include a plurality of conductive contact structures electrically connected to a plurality of semiconductor regions in or on the substrate 100b. A first metal foil 120a is provided, and can be Figure 4 It is shown pre-folded, or may be provided in an unfolded orientation and folded after the second solar cell 125b is provided.

[0096] The foil 120a may be positioned to the first solar cell 125a via vacuum, heat treatment, etc. An alignment method may be used to align 120a with 125b. Similarly, a second metal foil 120b may be provided and may be positioned to the second solar cell 125b via vacuum, heat treatment, etc. The metal foil 120a may be positioned over the back surface 131 of the solar cell 125a and the second adjacent solar cell 125b. The two solar cells 125a and 125b may be positioned adjacent to each other such that the metal foil 120a is below the substrate 100 of the first solar cell 125a and extends over the substrate 100b of the solar cell 125b.

[0097] According to the LAMP technique, the metal foil 120a may be exposed to a laser beam 108 in the following locations: above the conductive contact structures 110 and the solar cell 125b and above the back side 131 of the substrate 100 of the solar cell 125a. According to the processes and resulting structures disclosed above, the metal foil 120a is exposed to the laser beam 108 to form a plurality of conductive contact structures that electrically connect the metal foil 120a to the back side 131 of the substrate 100a of the solar cell 125a, and a plurality of conductive contact structures that electrically connect the metal foil 120a to the substrate 100b of the solar cell 125b. The conductive contact structures electrically connect regions of the substrate 100a and regions of the substrate 100b to the metal foil 120a, allowing electrons to flow to or from the substrate 100a and the substrate 100b, depending on the polarity of the connection.

[0098] Figure 5 A string 175 of exemplary solar cells 125 utilizing metal foil 120 is shown, which may be formed according to the methods and embodiments described herein. In this exemplary string of solar cells, there are 5 solar cells, but 2, 3, 4, 5, 6, 7, 8, 9, 10 or more solar cells may be connected in the string of solar cells. For example, in a super cell embodiment utilizing solar cell strips separated and fabricated from larger solar cells, 50 or 75 or more solar cell strips may be interconnected together utilizing LAMP technology.

[0099] As another example, Figure 6 Shown is a side view of a solar cell string (two cells) with an intermediate insulator.

[0100] See also Figure 6 , provides the above relative to Figures 1A to 1F The metal foil 120a is positioned on the back side 131 of the solar cell 125a. The metal foil 120a includes an insulating material 122, which in some embodiments is positioned and / or disposed on the metal foil 120a so that when the two solar cells 125a and 125b are connected and / or mounted, the insulating material 122 can inhibit a short circuit between the metal foil 120a and the second solar cell 125b electrically connected to the first solar cell 125a. As described above with respect to Figures 1A to 1FAs described, the metal foil 120 is exposed to a laser beam in a position above the back surface 131 of the solar cell 125a to form a plurality of conductive contact structures electrically connected to the back surface 131 of the substrate 100, and the plurality of conductive contact structures electrically connect the area of ​​the substrate 100 to the metal foil 120a. In the manner disclosed above, a conductive bonding portion 115 can be formed in a position above the conductive contact structure 110 of the solar cell 125b to electrically connect the metal foil 120a to the conductive contact structure 110 of the solar cell 125b.

[0101] As another example, Figure 7 A side view of a solar cell string (two cells) with multiple intermediate insulators is shown. Figure 7 , provides the above relative to Figures 1A to 1F The metal foil 120a is positioned on the back side 131 of the solar cell 125. Figure 7 , the metal foil 120 is positioned on the back side 131 of the solar cell 125a. The metal foil 120 includes insulating materials 122 and 124, which are positioned and / or disposed on the metal foil 120a in some embodiments so that when the two solar cells are connected and / or mounted, the insulating materials 122 and 124 can inhibit the short circuit between the metal foil 120a and the first solar cell 125a or the second solar cell 125b electrically connected to the first solar cell 125a. As described above with respect to Figures 1A to 1F As described, the metal foil 120 is exposed to a laser beam in a position above the back surface 131 of the solar cell 125a to form a plurality of conductive contact structures electrically connected to the back surface 131 of the substrate 100, and the plurality of conductive contact structures electrically connect the area of ​​the substrate 100 to the metal foil 120a. In the manner disclosed above, a conductive bonding portion 115 can be formed in a position above the conductive contact structure 110 of the solar cell 125b to electrically connect the metal foil 120a to the conductive contact structure 110 of the solar cell 125b.

[0102] See also Fig. 8A , a solar cell 125a is provided. The solar cell 125a may have any size or configuration, which does not include the back metallization provided above. In one embodiment, the solar cell 125a is made by the method described herein and as FIG. 14A to FIG. 14DAs shown. The solar cell 125a includes a plurality of conductive contact structures 110, which are electrically connected to a plurality of semiconductor regions in or on the substrate 100. The conductive contact structures 110 can be formed using conventional techniques, or can be formed using a laser deposition process as disclosed herein. Before the metal foil is connected to the first solar cell 125a, a second solar cell 125b is also provided. Therefore, a first metal foil 120a is further provided. Optionally, the metal foil 120a includes insulating materials 122 and 124, which are positioned and / or disposed on the metal foil in some embodiments so that when the two solar cells are connected and / or mounted, the insulating material will inhibit a short circuit between the metal foil and the back side 131 of the second solar cell or the front side of the first solar cell. The metal foil 120a can be pre-folded, as Fig. 8A As shown, or it can be unfolded. Foil 120a can be adhered to first solar cell 125a via vacuum, heat treatment, etc. Alignment methods can be used to align 120a with 125b. Similarly, a second metal foil 120b can be provided and can be adhered to second solar cell 125b via vacuum, heat treatment, etc.

[0103] See also Figure 8B , the metal foil 120a can be positioned over the back side 131 of the solar cell 125a and the second adjacent solar cell 125b. The two solar cells 125a and 125b can be positioned adjacent to each other so that the metal foil 120a is below the substrate 100 of the first solar cell 125a and extends over the metallization portion of the solar cell 125b (e.g., as shown), or alternatively, extends just over the solar cell 125b. A conductive bonding portion 115 is formed in a position over the conductive contact structure 110 of the solar cell 125b to electrically connect the metal foil 120a to the conductive contact structure 110 of the solar cell 125b. The conductive bonding portion 115 electrically connects the conductive contact structure 110 to the metal foil 120a, allowing electrons to flow. The bonding can be performed as described above.

[0104] refer to Fig. 9 , the solar cell string can be expanded into a multi-solar cell string, which optionally includes insulating materials 122 and 124, which are positioned and / or disposed on the metal foil 120 in some embodiments, so that when two adjacent solar cells 125 are connected and / or mounted, the insulating materials 122 and 124 can inhibit the short circuit between the metal foil 120 and the solar cells. In addition, it is expected that one or more multi-solar cell strings can be further coupled together to form a solar cell array, for example, by attaching bus bars at the ends of the cell strings in parallel and / or series arrangements.

[0105] See also Fig. 10A, the plurality of solar cells 125 are arranged such that the metal foil 120 extending from one solar cell 125 may extend over the metallization portion 110 of an adjacent solar cell 125. In a certain embodiment, an alignment process may be performed to align the solar cell 125 with the metal foil 120 over the metallization portion 110 of the adjacent solar cell 125. In a certain embodiment, the metal foil 120 may be arranged over the metallization portion 110 of the adjacent solar cell 125 using an automated process (e.g., using a robot or a vision system) or a manual process. Fig. 10A As shown, the metal foil 120 extends across the gap between adjacent solar cells 120, but in other embodiments, an edge portion of one solar cell may overlap an edge portion of an adjacent solar cell in a shingled configuration such that the portion of the metal foil connecting the adjacent solar cells is substantially covered or hidden between the overlapping edge portions.

[0106] See also Fig. 10B , exposing the metal foil 120 to the laser beam 108 in a position above the conductive contact structure 110 of the adjacent solar cell 125. Exposing the metal foil 120 to the laser beam 108 forms a plurality of conductive contact structures that electrically connect the conductive contact structure 110 and the metal foil 120 of the solar cell 125. The conductive contact structures electrically connect the conductive contact structure 110 to the metal foil 120, allowing electrons to flow. The conductive contact structures may be distributed evenly, in a certain pattern, or otherwise on the metal foil 120. Optionally, the foil 120 may be bent or folded to form a solar cell string. In addition, the overlapping portion of the foil 120 may be minimized to maximize the spatial efficiency of the resulting cell string. In a specific example, the gap between adjacent solar cells is about 1 mm.

[0107] Repeating this process for a plurality of adjacent solar cells can form a very long super cell. For example, when a solar cell strip of approximately 1 inch by 6 inches is used for each of the solar cells 125, a super cell of 50, 60, 70, 80, 100 or more solar cell strips can be formed. In this example, the LAMP technique in conjunction with adjacent solar cell strips can include an existing process of providing a solar cell wafer (e.g., a plurality of solar cell wafers, each approximately 6 inches), laser scribing the solar cell wafer to form approximately 1 inch wide solar cell strips from each of the solar cell wafers, and then cutting such solar cell strips to separate the strips from each other. The resulting strips are then aligned and the strips are bonded together with a metal foil using the LAMP technique.

[0108] Fig.11 Shown as FIG. 10A to FIG. 10B Yet another example of the construction shown. Fig.11According to some embodiments, the metal foil of a plurality of solar cells 125 is exposed to a laser beam 108 over the back and / or front sides of the solar cells 125. In a certain embodiment, a solar cell string may be formed by providing a plurality of solar cells 125 arranged such that a metal 120 extending from one solar cell 125 extends over a semiconductor substrate of an adjacent solar cell 125. The metal foil 120 may be exposed to a laser beam 108 or a plurality of laser beams 108 to form a plurality of electrically conductive contact structures electrically connected to the back and / or front sides of the semiconductor substrate of the solar cells 125. In this manner, the metal foil 120 may be used to provide positioning of the semiconductor substrates of adjacent solar cells 125 (e.g., as described below), and / or to connect the cells 125 into a solar cell string. In a certain embodiment, the electrically conductive contact structures described herein may be made by the methods described herein and as described herein. FIG. 14A to FIG. 14D In certain embodiments, in contrast to the embodiment shown in the figure, the first laser beam 108 or the plurality of laser beams 108 may be applied to the front side of the solar cell 125, and then the second laser beam or the plurality of second laser beams 108 may be applied to the back side of the solar cell 125. In certain examples, the laser beams 108 or the plurality of second laser beams 108 may be applied to the back side of the solar cell 125 in separate steps and / or in one process step (e.g. Fig.11 1 (shown) applies the laser beam 108 to the front and back sides of the solar cells. In addition, the laser beam 108 may be applied sequentially, for example, the front side 132 of one solar cell may be exposed to the laser beam 108, then the back side 131 of the adjacent solar cell 125 may be exposed to the laser beam 108, and so on. In addition, any order may be used, for example, the front side 132 of the first solar cell 125 may be exposed to the laser beam, the front side 132 of another third solar cell 125 may be exposed to the laser beam, and the back side 131 of the second solar cell may be exposed to the laser beam 108, etc.

[0109] Fig.12 The metal foil of a plurality of solar cells 125 is shown exposed to a laser beam 108 in a position on the back side and / or the front side of the solar cells 125. In one embodiment, see Fig.12 , a solar cell string may be formed by providing a plurality of solar cells 125 arranged such that a metal 120 extending from one solar cell 125 extends over a seed layer 177 on a semiconductor substrate of an adjacent solar cell 125. The metal foil 120 may be exposed to a laser beam 108 or a plurality of laser beams 108 to form a plurality of conductive contact structures electrically connected to the seed layer 177 of the solar cell 125, as shown. In a certain embodiment, the metal layer may be a metal seed layer. In a certain example, the metal seed layer may include a deposited layer of tin, tungsten, titanium, copper, silver, and / or aluminum. In a certain example, a sputtering process may be used to deposit the metal seed layer.

[0110] The metal foil 120 can be exposed to the laser beam 108 or multiple laser beams 108 to form a plurality of conductive contact structures electrically connected to the front side of the solar cell 125. In this way, the metal foil can be used to provide positioning of the semiconductor substrates of adjacent solar cells 125 (e.g., as described below), and / or to connect the cells 125 into a solar cell string. In certain embodiments, the conductive contact structures described herein can be made by the methods described herein and as shown in FIG. FIG. 14A to FIG. 14D In one embodiment, similar to Fig.11 As described above, the first laser beam 108 or multiple laser beams 108 can be applied to the front side of the solar cell 125, and then the second laser beam or multiple second laser beams 108 can be applied to the back side of the solar cell 125. In one example, the laser beam 108 can be applied to the back side of the solar cell 125 in separate steps and / or in one process step (e.g., Fig.11 108 is applied to the front and back sides of the solar cell. Alternatively, the laser beam 108 may be applied sequentially, for example, similar to Fig.11 In addition, any order may be used, for example, similar to Fig.11 In certain embodiments, exposing the solar cell 125 to the laser beam 108 may be used to bond the metal foil 120 to the metal seed layer 177. In certain examples, the bonding process may include a welding process such as laser welding.

[0111] Fig.13 is a plan view of a solar cell string according to some embodiments. As shown, a metal foil 120 may be electrically connected to a plurality of solar cells 100. As described above, the metal foil may be electrically connected to the solar cell through a locally deposited metal portion. Also as shown, the metal foil 120 may be positioned below a solar cell and positioned above an adjacent solar cell, wherein the metal foil connects the solar cells in the solar cell string. Although (as shown) the metal fingers 201 may extend from the metal foil 120, in some embodiments, the metal foil may terminate at the bus bar portion of the solar cell 100, and another metallization structure may extend from the bus bar portion. In a certain example, the metal foil may be positioned above the bus bar portion of the solar cell 100, and a metal paste, electroplated metal, or other metal foil may extend as a metal finger over the solar cell 100. The metal fingers 201 may be formed by removing a portion of the metal foil 120 that has not been processed by the LAMP technology.

[0112] FIG. 14A to FIG. 14D Cross-sectional views of an exemplary solar cell illustrating various operational steps in a method of fabricating the solar cell.

[0113] See also Fig.14A, an intermediate layer 102 is formed on or over a solar cell substrate 100. The intermediate layer 102 has an opening 104 therein. Although specific reference is made to forming the intermediate layer on or over a substrate, it should be understood that the above directions are relative and that the intermediate layer may be formed on the back side, front side, or even both the back side and the front side of a selected substrate, such as for metallization of the front side, back side, or both the front side and the back side of a substrate.

[0114] The intermediate layer 102 is formed with the opening 104 (eg, patterned as deposited), or the opening 104 is formed in a blanket deposited intermediate layer. In the latter case, in one embodiment, the opening 104 is formed in the intermediate layer 102 by patterning using laser ablation and / or photolithography and etching processes.

[0115] The intermediate layer 102 may be formed on the back side of the substrate 100 opposite to the light receiving side 101 of the substrate 100. A passivation layer and / or an intermediate layer (eg, ARC) may also be formed on the back side of the substrate 100. Specifically, the intermediate layer 102 may be a backside anti-reflective coating (BARC).

[0116] The light receiving surface 101 may have a textured light receiving surface. A hydroxide-based wet etchant may be used to texture the light receiving surface 101 of the substrate 100. A textured surface is a surface having a regular or irregular shape that is used to scatter incident light and reduce the amount of light reflected away from the light receiving surface 101 of the solar cell. A passivation and / or insulation (e.g., ARC) layer may be formed on the light receiving surface 101.

[0117] Although the present disclosure is primarily directed to back-contact solar cells, the methods and techniques discussed herein, particularly the LAMP technology, can be applied to the metallization of substrates in other types of solar cells, such as front-contact solar cells (e.g., PERC solar cells, mono-PERC solar cells, HIT solar cells, TopCon solar cells, PERL cells and tandem cells, as well as other types of solar cells).

[0118] The opening 104 in the intermediate layer 102 may expose portions of a plurality of semiconductor regions formed in or on the substrate 100, including portions of a plurality of first and second semiconductor regions (e.g., N-type and P-type semiconductor regions or vice versa) formed in or on the substrate 100. The substrate 100 may be a single crystal silicon substrate (such as a bulk single crystal N-type doped silicon substrate) or a layer (such as a polycrystalline silicon layer) disposed on a single crystal solar cell substrate. The substrate 100 may have N-type doped regions and P-type doped regions disposed therein / on it, portions of which are exposed through the opening 104 in the intermediate layer 102. In front contact solar cell embodiments, the semiconductor regions on one side of the solar cell may have the same conductivity type (e.g., P-type or N-type).

[0119] The N-type and / or P-type semiconductor regions may be disposed on a dielectric layer, such as a tunneling oxide layer including silicon oxide having a thickness of about 2 nanometers or less. The N-type and / or P-type semiconductor regions may be formed of polysilicon, which is formed, for example, by a plasma enhanced chemical vapor deposition (PECVD) process. The N-type polysilicon emitter region may be doped with N-type impurities, such as phosphorus, and the P-type polysilicon emitter region may be doped with P-type impurities, such as boron. In a certain embodiment, the N-type and P-type semiconductor regions are separated from each other. In a certain example, the N-type and P-type semiconductor regions have a trench or an intrinsic (or lightly doped) region formed therebetween. The trench may extend partially into the substrate and be covered by the intermediate layer 102. The doping concentration of the lightly doped region may be significantly less than that of the N-type and P-type semiconductor regions. A dielectric layer (e.g., a tunneling oxide or silicon dioxide layer) may be positioned between the N-type and P-type semiconductor regions, and may be positioned laterally between the N-type and P-type semiconductor regions.

[0120] See also Fig. 14B , the metal foil 106 is positioned above the intermediate layer 102. In certain embodiments, positioning the metal foil 106 above the intermediate layer may include placing the metal foil above the substrate 100. In certain examples, positioning the metal foil 106 above the substrate 100 may include covering the entire substrate 100. In certain embodiments, a portion of the metal foil 106 may be positioned above the substrate 100, and other portions may be positioned away from the substrate 100, such as extending away from the substrate 100 in a lateral direction, such as Fig. 14BAs shown. In a certain embodiment, in order to fix the metal foil 106 with the substrate 100, a positioning process may be performed, including using a vacuum and / or a stitching process to appropriately fix the metal foil 106 on the substrate 100. In a certain example, the positioning process includes performing a hot pressing process. In another example, the metal foil 106 may be disposed or positioned on the substrate 100 using a roller. In a certain embodiment, a vacuum process, a hot pressing process, or other similar processes may uniformly dispose the metal foil to suppress the formation of air gaps or air pockets between the metal foil and the substrate, as shown. In a certain example, the metal foil 106 may be disposed on the substrate 100 using a roller.

[0121] The metal foil 106 may have a surface area that is significantly larger than the surface area of ​​the solar cells when the metal foil 106 is positioned over the substrate 100. However, in another embodiment, before the metal foil 100 is placed over the solar cells, the large foil may be cut to provide the metal foil 106 with a surface area that is substantially the same as the surface area of ​​the substrate 100. For example, the metal foil may be laser jet cut, water jet cut, etc., before or even after the metal foil is placed on or over the substrate 100.

[0122] See also Fig. 14C , the metal foil 106 may be exposed to the laser beam 108 in a position above the opening 104 in the intermediate layer 102, the opening exposing a portion of the semiconductor region in or above the substrate 100. In a certain embodiment, a region of the metal foil 106 is selectively exposed to the laser beam 108 in a position at least partially above the opening 104 in the intermediate layer 102. In some embodiments, the metal foil 106 is exposed to the laser beam 108 in a position offset from the opening 104 in the intermediate layer 102 (e.g., partially above the opening or not above the opening). In a certain example, the metal foil 106 is exposed to the laser beam 108 in a position adjacent to the opening 104.

[0123] See also Fig.14D The metal foil 106 is exposed to a laser beam 108 to form a plurality of conductive contact structures 110 electrically connected to semiconductor regions in or on the substrate 100 .

[0124] According to one or more embodiments of the present disclosure, each conductive contact structure 110 is or includes a locally deposited metal portion. In one such embodiment, since the metal foil 106 is first placed on the substrate surface, the metal foil 106 is used as a source or metal and is referred to as a local source. The metal foil 106 is then exposed to a laser process, such as a laser beam, to deposit metal from the metal foil 106 (metal source) onto a portion of the substrate. It should be understood that the resulting locally deposited metal portion may have edge features that can be distinguished from metal structures formed by other deposition processes (such as electroplating, welding, or thermal bonding that can provide conformal structures without edge features).

[0125] See again Fig.14D , the second portion or portions 112 and 114 of the metal foil 106 that are not exposed to the laser beam 108 remain on the intermediate layer 102. As shown, portion 112 is a central portion, while portion 114 is an edge portion and may be an overhanging portion. In certain embodiments, such second portions are not deposited or fixed to the solar cell or intermediate layer 102. In a certain embodiment, Fig.14D The structure is implemented as a solar cell without removing portions 112 and / or 114 of the metal foil 106. Such a structure can be used for the back surface metallization of a front-side contact solar cell.

[0126] Re-reference FIG. 14A to FIG. 14D After exposing the metal foil 106 to the laser beam 108, portions 112 and 114 of the metal foil 106 may be removed, and portion 112 may be selectively exposed to the laser beam. FIG. 15A to FIG. 15C shown.

[0127] FIG. 15A to FIG. 15C FIG. 4 shows a cross-sectional view of a solar cell. Fig.15A As shown, removing the second portion of the metal foil may leave a conductive contact structure 110 at a location in the intermediate layer 102 having exposed portions of a plurality of N-type and / or P-type semiconductor regions in or on the substrate 100. Fig. 15B , the formation of sharp or torn edge features 113 on either side of the conductive contact structure 110 is shown. As described above, these edge features 113 are formed by removing a second portion of the metal foil that is not exposed to the laser beam. In some embodiments, some portions 112 and 114 are removed, and other portions 112 and 114 are retained. In a certain embodiment, exposing the metal foil 106 to the laser beam 108 includes removing all or substantially all portions of the metal foil that are not exposed to the laser beam.

[0128] Fig. 15CThe positions of N-type and / or P-type semiconductor regions 105 are shown. In the illustrated embodiment, the N-type and / or P-type semiconductor regions 105 are separated from each other, and each semiconductor region has two conductive contact structures 110. An alternative (not shown) includes one, three or more conductive contact structures in each semiconductor region. In a certain example, the N-type and / or P-type semiconductor regions may have trenches formed therebetween, which extend partially into the substrate and are covered by the intermediate layer 102. In one example, the N-type and / or P-type semiconductor regions may be separated by an intrinsic or lightly doped region therebetween, for example, wherein the doping concentration of the lightly doped region may be significantly less than that of the N-type and / or P-type semiconductor regions. In some embodiments, as with some front-contact solar cells, the semiconductor regions 105 may have the same conductivity type, both N-type or P-type. As described above, it is contemplated that the conductive contact structure 110 may be enhanced with the second metal source.

[0129] Re-reference FIG. 14A to FIG. 14D After applying the laser beam 108 to the metal foil 106, in one example, only portions 114 of the metal foil 106 that were not exposed to the laser beam 108 are removed, while certain portions 112 of the metal foil 106 remain. In one embodiment, the portions 112 may be selectively exposed to the laser beam 108 or a different / subsequent laser beam, which may use the same laser with different laser settings / variants.

[0130] Fig.16 A cross-sectional view of a solar cell is shown. Fig.16 As shown, the laser forms a conductive contact structure 110 and a portion 112 on the intermediate layer 102 (such as an ARC or BARC layer). Portion 114 has been removed. The location of the N-type and / or P-type semiconductor region 105. In one example, the N-type and / or P-type semiconductor region is separated by, for example, a lightly doped region 197 therebetween, for example, wherein the doping concentration of the lightly doped region may be significantly less than that of the N-type and / or P-type semiconductor region. In some embodiments, as with some front-contact solar cells, the semiconductor region 105 may have the same conductivity type, both N-type or P-type. As described above, it is contemplated that the conductive contact structure 110 may be enhanced with the second metal source. As described above, it is further contemplated that portion 112 may be formed by the second metal source.

[0131] FIG. 17A to FIG. 17EAn exemplary semiconductor substrate manufactured using the methods, methods or devices described herein according to some embodiments is shown. The semiconductor substrate is a solar cell 1520a to a solar cell 1520e and may include a silicon substrate 1525. The silicon substrate 1525 may be cleaned, polished, planarized and / or thinned or otherwise processed. The semiconductor substrate 1525 may be an N-type or P-type single crystal silicon or polycrystalline silicon substrate. The solar cell may have a front side 1502 and a back side 1504, wherein the front side 1502 is opposite to the back side 1504. The front side 1502 may be referred to as a light receiving surface 1502, and the back side 1504 may be referred to as a back surface 1504. The solar cell may include a first doped region 1521 and a second doped region 1522. In a certain embodiment, the first doped region may be a P-type doped region (e.g., doped with boron), and the second doped region may be an N-type doped region (e.g., doped with phosphorus). Solar cells 1520a-1520e may include an intermediate layer (e.g., an anti-reflective coating ARC) 1528 on the front side 1502 of the solar cell. Solar cells 1520a-1520e may include a back side intermediate layer (e.g., a back side anti-reflective coating BARC) 1526 on the back side 1504 of the solar cell.

[0132] Fig.17A An exemplary back-contact solar cell manufactured using the methods, means or apparatus described herein is shown. The back-contact solar cell 1520a may include a first doped region 1521 and a second doped region 1522 disposed on the back side 1504 of the solar cell 1520a. In a certain example, the first doped region 1521 and the second doped region 1522 may be doped semiconductor regions. The first doped region 1521 and the second doped region 1522 may be doped polysilicon regions. A thin oxide layer 1573 (e.g., a tunneling oxide layer) may be disposed between the first doped region 1521 and the second doped region 1522 and the substrate 1525. In contrast, the first doped region 1521 and the second doped region 1522 may be positioned in the substrate 1525. Conductive contact structures 1511, 1512 are positioned on the back side 1504 of the solar cell 1520a, wherein the conductive contact structures 1511, 1512 include locally deposited metals on the first doped region 1521 and the second doped region 1522. The first doped region 1521 and the second doped region 1522 may have a separation region 1577 formed therebetween. In one example, the first doped region 1521 and the second doped region 1522 have trenches formed therebetween, which partially extend into the substrate and are covered by the intermediate layer 1562. The trenches may be replaced by intrinsic or lightly doped semiconductor regions.

[0133] Fig. 17BAnother example of a back-contact solar cell 1520b manufactured using the methods, means, or apparatus described herein according to some embodiments is shown. The back-contact solar cell 1520b may include a first doped region 1521 and a second doped region 1522 disposed on the back side 1504 of the solar cell 1520b. In a certain example, the first doped region 1521 and the second doped region 1522 may be extending to a doped semiconductor region in a continuous layer. In one example, the first doped region 1521 and the second doped region 1522 are separated by a lightly doped region 1579 therebetween, for example, wherein the lightly doped region may have a doping concentration significantly less than the first doped region 1521 and the second doped region 1522. In a certain embodiment, a thin oxide layer 1573 (e.g., a tunneling oxide layer) may be disposed between the first doped region 1521 and the second doped region 1522 and the substrate 1525. In a specific embodiment, the first doped region 1521 and the second doped region 1522 may be doped polysilicon regions. Instead, the first doped region 1521 and the second doped region 1522 may be located in the substrate 1525. In one embodiment, the conductive contact structures 1511, 1512 are on the back side 1504 of the solar cell 1520c, wherein the conductive contact structures 1511, 1512 include locally deposited metal formed on the first doped region 1521 and the second doped region 1522 via LAMP technology.

[0134] Fig. 17C An exemplary front-contact solar cell manufactured using the methods, means, or apparatus described herein according to some embodiments is shown. The front-contact solar cell 1520c may include a first doped region 1521 disposed on the back side 1504 of the solar cell 1520c. In a certain example, a second doped region 1522 may be disposed on the front side 1502 of the solar cell 1520c. Although one example of the second doped region 1522 is shown, one or more of the second doped regions 1522 may be used. Conductive contact structures 1511, 1512 may be on the front side and back side 1504 of the solar cell 1520c, wherein the conductive contact structures 1511, 1512 include locally deposited metal formed on the first doped region 1521 and the second doped region 1522 via LAMP technology. The second doped region 1522 may be offset from the first doped region 1521, as shown. The second doped region 1522 may be aligned with the first doped region 1521, for example, vertically aligned.

[0135] Fig.17DAn exemplary front-contact solar cell manufactured using the methods, means, or apparatus described herein according to some embodiments is shown. The front-contact solar cell 1520d may include a first doped region 1521 disposed on the back side 1504 of the solar cell 1520d. The conductive contact structures 1511, 1512 may be on the front side 1502 and the back side 1504 of the solar cell 1520d, respectively, via the LAMP technique, wherein the conductive contact structures 1511, 1512 include locally deposited metals on the first doped region 1521 and the second doped region 1522. The first doped region 1521 and the second doped region 1522 may include amorphous silicon regions. The solar cell 1520b may include an intermediate layer (e.g., an anti-reflective coating ARC) 1526 on the front side 1502 of the solar cell 1520d. The solar cell 1520d may include a back intermediate layer (e.g., a back anti-reflective coating BARC) 1526 on the back side 1504 of the solar cell 1520b. A thin oxide layer 1530 may be disposed between the first doping region 1521 and the substrate 1525 .

[0136] Fig.17E Another exemplary front-contact solar cell manufactured using the methods, means or apparatus described herein according to some embodiments is shown. Solar cell 1520e may include first doped regions 1521a, 1521b disposed on the back side 1504 of solar cell 1520e. In a certain example, second doped regions 1522a, 1522b may be disposed on the front side 1502 of solar cell 1520d. In a certain embodiment, conductive contact structures 1511, 1512 may be disposed on the front side and back side 1504 of solar cell 1520b, respectively, via LAMP technology, wherein conductive contact structures 1511, 1512 include locally deposited metal on first doped regions 1521a, 1521b and second doped regions 1522a, 1522b. The first doped regions 1521a, 1521b may include doped polysilicon regions. Solar cell 1520e may include an intermediate layer (e.g., an anti-reflective coating ARC) 1526 on the front side 1502 of solar cell 1520e. The solar cell 1520e may include a back side intermediate layer (eg, a back side anti-reflective coating (BARC)) 1526 on the back side 1504 of the solar cell 1520e.

[0137] 18A to 18CA side view of operations in a method of manufacturing a solar cell string according to one embodiment of the present disclosure is shown. Referring to FIG. 21A , two solar cells 125 a and 125 b as described above are provided, which include a substrate 100. The substrate includes a plurality of conductive contact structures 110 electrically connected to the substrate 100, and a second portion 114 of the metal foil 106 that is not exposed to the laser beam 108 remains on the substrate 100, overhangs and / or extends from the substrate 100. Although shown as separated, the conductive contact structures 110 and the second portion 114 may be continuous. The solar cells 125 a and 125 b are stacked together in the same orientation. The second portion 114 is joined together at a position 111 to form a joint 115, as shown. Fig.18B As shown. In one embodiment, the bonding can be accomplished by a laser process as described herein. In one embodiment, the bonding is a welding process, such as laser welding, ultrasonic welding, or induction welding. In an embodiment, the bonding can be accomplished by thermocompression bonding. In one embodiment, the bonding is accomplished by a conductive adhesive. This process can also be used to attach two solar cells. Solar cells 125a and 125b can be spread out as shown by the arrows to form a linear string. As shown Fig.18B As shown, this process can be repeated multiple times to form an almost infinite string of cells, such as by adding solar cells 125c, as shown in FIG. Fig.18B Although Fig.18C 3 solar cells are shown in the figure, but 2, 3, 4, 5, 6 or more solar cells may be connected in a solar cell string. In addition, different procedures and steps may be performed to form the solar cell string shown. In a certain embodiment, the strings of solar cells may be connected together by stacking the strings together and bonding a metal foil extending from one solar cell at the end of a first solar cell string to a complementary metal foil extending from a solar cell at the end of a second solar cell string stacked on top of the first solar cell string.

[0138] Fig.19A and 19B An enlarged view of an exemplary interconnection of a metal ribbon 14 to solar cells 125a and 125b is shown, such as at the end of a string of solar cells. Fig.19A , metal ribbon 14 is connected to the back side of each of solar cells 125a and 125b, for example, to form a set of two (or more) parallel-connected solar cell strings. Fig.19B The metal ribbon 14 is connected to the back side of the solar cell 125a and the front side of the solar cell 125b, for example, to form a set of two (or more) solar cell strings connected in series. Fig.19BAs shown, the metal ribbon 14 may be threaded or woven in an over / under configuration between strings of adjacent solar cells. The metal ribbon 14 may extend at either end, for example, to electrically connect to additional strings and / or other components of a solar cell array, matrix, and / or system.

[0139] Although certain materials are specifically described with reference to the above embodiments, in such embodiments, other materials may be easily substituted for some of the materials, and these embodiments are still within the spirit and scope of the embodiments of the present disclosure. For example, in a certain embodiment, a substrate of a different material, such as a substrate of a III-V material, may be used instead of a silicon substrate. In another embodiment, any type of substrate used in the manufacture of microelectronic devices may be used instead of a silicon substrate, for example, a printed circuit board (PCB) and / or other substrates may be used. In addition, although primarily reference is made to back-contact solar cell arrangements, it should be understood that the methods described herein may also be applied to front-contact electrode solar cells. In other embodiments, the above methods may be applicable to manufacture other than solar cells. For example, the manufacture of light emitting diodes (LEDs) may benefit from the methods described herein.

[0140] In addition, although solar cells are described in detail herein, the methods and / or processes described herein can be applied to various substrates and / or devices (e.g., semiconductor substrates). For example, semiconductor substrates can include solar cells, light-emitting diodes, micro-electromechanical systems, and other substrates.

[0141] Furthermore, although many of the embodiments described herein involve making direct contact between a semiconductor and a metal foil as a metal source, the concepts described herein may also be applicable to solar applications (e.g., HIT cells) where contact is made with a conductive oxide (such as indium tin oxide (ITO)) rather than directly contacting the semiconductor. Additionally, embodiments may be applicable to other patterned metal applications, such as PCB trace formation.

[0142] Therefore, local metallization of semiconductor substrates using laser beams and the resulting structures are proposed.

[0143] Although specific embodiments have been described above, even if only a single embodiment is described with respect to a particular feature, these embodiments are not intended to limit the scope of the present disclosure. Unless otherwise specified, the examples of features provided in the present disclosure are intended to be illustrative rather than limiting. The above description is intended to cover those alternatives, modifications, and equivalents that will be apparent to those skilled in the art that have the beneficial effects of the present disclosure.

[0144] The scope of the present disclosure includes any feature or combination of features disclosed herein (expressly or implicitly), or any generalization thereof, whether or not it mitigates any or all of the problems addressed herein. Accordingly, new claims may be made for any such combination of features during the examination process of the present application (or an application claiming priority thereto). In particular, with reference to the appended claims, features from dependent claims may be combined with those of the independent claims, and features from corresponding independent claims may be combined in any appropriate manner, and not just in the specific forms enumerated in the appended claims.

Claims

1. A solar cell string, comprising: a first solar cell having a front side and a back side, wherein the front side is a light receiving side of the first solar cell; a second solar cell having a front side and a back side, wherein the front side is a light receiving side of the second solar cell; a metal foil disposed on the back surface of the first solar cell and on the metal portion of the front surface of the second solar cell; one or more laser-assisted metallization conductive contact structures each having a discrete locally deposited metal portion electrically connected to the back side of the first solar cell, wherein the discrete locally deposited metal portion of each of the one or more laser-assisted metallization conductive contact structures is formed from the metal foil and is separate from the entirety of the metal foil such that the discrete locally deposited metal portion is not connected to the entirety of the metal foil; one or more laser-assisted metallization electrically conductive contact structures each having a discrete locally deposited metal portion electrically connected to the front side of the second solar cell, wherein the discrete locally deposited metal portion of each of the one or more laser-assisted metallization electrically conductive contact structures is formed from the metal foil and is separate from the entirety of the metal foil such that the discrete locally deposited metal portion is not connected to the entirety of the metal foil; and an insulating material located on at least a portion of the front side of the metal foil and / or the back side of the metal foil, wherein the insulating material is selectively patterned and the insulating material selectively electrically separates the portion of the metal foil where the insulating material is located from at least one of the first solar cell and the second solar cell; The insulating material contacts at least one of the first solar cell and the second solar cell only at an edge thereof. 2 . The solar cell string of claim 1 , wherein the metal foil extends over a portion of the front side of the second solar cell. 3 . The solar cell string of claim 1 , wherein the second solar cell comprises one or more contact pads, and wherein the metal foil is electrically connected to the one or more contact pads of the second solar cell. 4 . The solar cell string of claim 1 , further comprising one or more additional solar cells electrically connected to the first solar cell or the second solar cell. 5 . The solar cell string of claim 1 , wherein the metal foil is folded between the first solar cell and the second solar cell. 6 . The solar cell string of claim 1 , wherein the first solar cell and the second solar cell include P-type and N-type doped diffusion regions.

7. The solar cell string of claim 1, further comprising a capping material over a portion of the metal foil between the solar cells.

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