Reactive Ion Etching Processes for Solar Cell Fabrication

A method for preparing solar cells that enables efficient copper seed layer formation for gate electrode deposition. The method involves depositing a protective gas plasma in a controlled hydrogen environment to create a thin copper seed layer on a transparent conductive film, followed by a second copper layer deposition. This sequential process enables the formation of a uniform copper seed layer suitable for subsequent gate electrode deposition, significantly improving the efficiency and quality of solar cell fabrication.

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A method for preparing solar cells that significantly enhances etching speed and reduces etching time for transparent conductive layers. The method employs a novel acid concentration strategy that maintains a controlled concentration of etching agents while achieving higher etching rates compared to conventional wet etching methods. The controlled acid concentration enables precise control over etching conditions, particularly for difficult-to-etch transparent conductive layers, while minimizing etching liquid usage and volatilization. The method enables rapid etching of transparent conductive layers, enabling faster solar cell production.

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Highly efficient back-contacted solar cell with passivated contacts that reduces recombination and improves efficiency. The cell has interdigitated electrodes on the back contacting doped regions of opposite polarity. The doping in the regions is balanced to create the opposite polarity. This eliminates the need for complex doping steps or masks on the back. The front has lower doping compared to the back. Passivation layers on front and back further reduce recombination. The cell is manufactured by depositing a polycrystalline silicon layer on a dielectric layer, locally doping the back regions, and forming passivation layers.

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Enhancing the etching rate of silicon nitride films in plasma processing by combining iodine heptafluoride (IF7) plasma with an inert gas. The method utilizes a plasma generated by converting IF7 into plasma to etch the silicon nitride film simultaneously with the formation of a silicon oxide film. The IF7 plasma provides high etch rates for the silicon nitride, while the oxide film acts as a sacrificial mask. This approach enables simultaneous etching of both silicon nitride and silicon oxide films at elevated etch rates.

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A novel etching method for photovoltaic cells that enables the removal of the silicon-arsenic (a-Si) transition layer through enhanced physical etching without replacing etching gases or equipment. The method employs reactive ion etching (RIE) with chlorine and sulfur hexafluoride as the etching gas, which generates reactive plasma that selectively targets and breaks through the transition layer. This approach addresses the conventional challenge of removing the transition layer through dry etching without damaging the underlying silicon.

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Method for manufacturing tandem solar cells by selectively removing pyramid-shaped defects from a crystalline silicon substrate surface through a combination of isotropic and anisotropic etching processes. The method employs a novel etching sequence that balances isotropic etching for surface roughness control with anisotropic etching for precise defect removal, enabling the formation of uniform unit layers without compromising the substrate's surface integrity.

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Etching method and application of silicon nitride in crystalline silicon solar cells, particularly for achieving low-temperature sintering and lead-free metallization. The method involves using tellurium glass as the front electrode in crystalline silicon solar cells, where tellurium glass forms a stable silver-silicon contact through oxidation. The tellurium glass powder is melted during the sintering process, forming a stable glass-oxide interface that enables the formation of a high-quality silver-silicon contact. This approach enables the use of tellurium glass in crystalline silicon solar cells, particularly for low-temperature sintering and lead-free metallization, while maintaining high efficiency and performance.

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Method for manufacturing high-efficiency crystalline silicon-based solar cells with integrated intrinsic silicon layers and conductive silicon-based layers. The method employs plasma treatment to form intrinsic silicon layers on the substrate surface during CVD processing. The plasma treatment introduces hydrogen gas into the chamber while maintaining a controlled silicon-containing gas flow, which enhances film quality and passivation while suppressing variations in conversion characteristics. The intrinsic silicon layers are formed in the valleys of the substrate texture, while the conductive silicon-based layers are formed in the valleys and mid-abdomen regions. The plasma treatment achieves controlled film thickness distribution between substrates while maintaining uniform film quality.

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Plasma etching method using a novel etchant that replaces conventional fluorinated gases with heptafluoropropyl methyl ether (HFE) gas, while maintaining the etchant's environmental benefits. The HFE gas, combined with argon (Ar) and oxygen (O2), produces a plasma etching process with improved etching characteristics for high-aspect-ratio structures, while minimizing the etchant's global warming potential. The plasma density can be controlled by adjusting the Ar flow rate, enabling the formation of anisotropic etched patterns.

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Plasma etching method using an etchant with low global warming potential (GWP) for semiconductor device manufacturing. The method employs a combination of hexafluoroisopropanol (HFIP) and argon (Ar) gases in a plasma chamber. By heating the HFIP canister to 75°C and the Ar line to 135°C, HFIP vaporizes and enters the plasma chamber, where it reacts with Ar to form an etching target. This dual-gas approach enables the formation of anisotropic etched patterns through enhanced ion bombardment, while maintaining the environmental benefits of HFIP.

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Plasma-curing of light-receiving surfaces for solar cells enhances performance and stability through a novel fabrication process. The process involves growing a phosphorous-doped oxide layer and an anti-reflective coating (ARC) layer in a plasma-enhanced chemical vapor deposition (PECVD) tool. The ARC layer is formed directly on the phosphorous-doped oxide layer, eliminating the need for intermediate layers. Plasma-induced radiation during the ARC deposition process creates a protective layer that prevents hot electron injection across the interface, thereby reducing interface wear and degradation. The plasma-cured solar cell exhibits improved front surface field (FSF) performance, enhanced UV stability, and enhanced overall solar cell efficiency compared to conventional methods.

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Etching process for III-V semiconductor materials, particularly indium phosphide (InP), that enhances aspect ratio through repeated etching cycles. The process involves three sequential steps: initial isotropic etching, followed by anisotropic etching with a passivation layer, and repeated etching cycles. This multi-step approach enables controlled removal of material from the bottom of the structure while maintaining sidewall integrity, resulting in structures with improved aspect ratios.

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A novel texturing agent for silicon wafers that enhances yield and efficiency of photovoltaic cells produced from diamond wire-cut silicon wafers. The agent combines hydrogen peroxide with a specific etching solution composition that precisely controls the etching process. The composition is optimized to maintain optimal etching conditions while minimizing the formation of undesirable amorphous silicon layers. This agent enables improved surface preparation for photovoltaic cells, resulting in higher efficiency conversion rates compared to conventional methods.

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Process for etching the surface of cadmium telluride solar cells to improve cell efficiency and appearance. The process involves selectively etching the positive side of the solar cell while maintaining the negative side intact. The etching is performed using a controlled atmosphere environment that prevents the formation of acid droplets during the etching process. This controlled environment enables precise control over the etching conditions and prevents the formation of unwanted cadmium telluride spots on the positive side of the solar cell.

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Etching silicon films using an iodine heptafluoride gas with a controlled flow ratio of basic gas. The etching process involves supplying the iodine heptafluoride gas and basic gas to the substrate while maintaining a specific flow ratio between the two gases. This controlled ratio enables precise control over the etching conditions, particularly in achieving high uniformity and suppressing roughness during the wet etching step.

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A process for etching silicon wafers that combines a pretreatment step with an F2-containing gas etching process, enabling improved etch rates and reduced reflection characteristics in photovoltaic applications. The pretreatment step uses an HF-containing gas mixture to modify the silicon surface before etching with F2-containing gas, while the F2-containing gas etches the modified surface. This combined approach enables enhanced etch properties and reduced reflection characteristics compared to conventional F2-based etching methods.

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A plasma texturing method for crystalline solar cells that achieves improved surface roughness without the need for chlorine gas. The method employs a process gas mixture containing N2 (95-99%), NF3 (0.5-3%), O2 (0.2-1%), and H2 (0.2-1%) in a heated crystalline solar cell. The process gas is optimized to achieve the best reflectance at 600-1000 nm. When the H2 gas is discharged, it increases plasma density through electron excitation, effectively creating micro-textured surface features that enhance solar reflectance. This approach enables high-quality solar cell texturing without the need for traditional chlorine-based plasma processing.

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Safe and controllable RIE texturing process for solar silicon wafers that eliminates the need for hazardous gases like SF6 and 02. The process employs a unique pipeline system that provides both gas supply and SiCL4 for the reaction chamber, with the gas mixture ionized by plasma glow discharge. This configuration enables controlled reaction conditions while minimizing the need for hazardous chemicals.

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A method for manufacturing heterojunction solar cells that improves conversion efficiency through controlled hydrogen plasma treatment of the intrinsic silicon layer. The treatment introduces hydrogen gas in a controlled ratio to silicon-containing gas, achieving plasma power densities up to 80 mW/cm². This controlled plasma environment enables uniform hydrogen incorporation into the intrinsic silicon layer, suppressing characteristic variations in the solar cell's performance characteristics. The treatment can be performed during deposition or as a post-deposition process, with the introduction gas ratio optimized for the specific deposition conditions.

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A solar cell backside etching process that improves the etching efficiency and quality of solar cells by controlling the etching conditions. The process employs a controlled water film formation step followed by selective etching of the backside oxide layer using a fluorine-based etchant. The etchant is precisely controlled to achieve a uniform and controlled removal of the oxide layer, while maintaining a protective water film on the silicon surface. The process also employs a series of post-etching steps, including alkaline washing and ozone treatment, to ensure thorough removal of residual etchant residues and prevent post-etching defects.

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Selective etching of emitter in solar cells using printed grid lines as a self-mask. The process improves solar cell efficiency by controlling plasma process parameters through a novel use of printed grid lines as a selective etching mask. The grid lines act as a self-mask, protecting the emitter while allowing plasma etching of the underlying wafer. This approach enables the selective etching of emitter regions while maintaining uniformity and preventing unwanted etching of the wafer surface.

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Method for optimizing solar cell surface modification through controlled etching using a gas mixture containing fluorine (F2) and hydrogen fluoride (HF) with specific concentrations. The etching process, which involves a controlled atmosphere of fluorine-containing gases, enables precise control over etching rate, depth, and pattern formation. The method enables the creation of solar cells with reduced reflectance, which can be beneficial for solar panel applications.

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Dry etching process for crystalline silicon solar cells that utilizes a low-concentration alkali solution to remove damaged surface layers while preserving minority carrier lifetime. The process employs dry etching to create textured surface features, followed by a controlled removal of damaged regions using a low-concentration alkali solution to restore the surface structure. This approach enables the creation of textured surfaces while maintaining carrier lifetime through precise control over etching conditions.

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Surface mount multijunction photovoltaic cells with through-wafer vias that enable efficient interconnection while minimizing etching complexity. The cells feature through-wafer vias that extend from the wafer surface to the back contact, eliminating the need for conventional interconnects and bypass diodes. The vias are formed through a single-step wet etching process using a single-reactant chemistry that achieves passivation and sidewall quality. The vias serve as both interconnects and sidewall passivation layers, enabling reliable and low-cost interconnection of multijunction photovoltaic cells.

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Enhancing solar cell efficiency through surface modification of protective substrates using plasma treatment. The process involves introducing a plasma gas mixture containing fluorinated gases (CxFy) or hydrocarbons (CxHy) to create a polymer coating on the substrate surface. The plasma treatment creates a thin, hydrophobic polymer layer that reduces reflected light and enhances self-cleaning properties of the substrate. The treatment apparatus can be integrated into existing solar cell manufacturing processes, eliminating the need for substrate replacement.

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A method for improving the reflectivity and absorption efficiency of solar cells by processing the back surface before aluminum paste application. The processing involves etching the silicon wafer surface with a mixture of hydrogen fluoride (HF) and hydrogen peroxide (HN03) at elevated temperatures. This etching step creates a textured surface that enhances the aluminum paste's adhesion and promotes uniform light distribution. The resulting polished back surface provides a mirror-like finish for the solar cell, enabling improved light absorption and conversion efficiency.

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Enhancing solar cell efficiency through plasma-enhanced hydrogen treatment of the front protection layer. The process involves injecting hydrogen into the front protection layer during the manufacturing process, specifically after the electrode formation step. The hydrogen plasma treatment creates a protective layer that enhances the solar cell's photoelectric conversion efficiency by reducing surface recombination and improving charge carrier mobility. The treatment is performed after the electrode formation step, before the second electrode is formed, and the plasma is created at temperatures between 250°C and 800°C.

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A solar cell manufacturing method and polishing process that enables precise back polishing of solar cells during polysilicon deposition, while maintaining high efficiency and preventing front surface damage. The process involves a specialized wet etching machine that removes the polysilicon layer from the solar cell substrate, with the polishing surface facing the corrosive etching solution. The etching solution selectively removes the silicon nitride anti-reflective coating, creating a clean surface for subsequent polysilicon deposition. This approach eliminates the front polishing step, which can compromise the solar cell's electrical properties, while maintaining the anti-reflective coating integrity. The wet etching process enables precise control over the polishing depth and surface topography, ensuring optimal solar cell performance.

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Etching photovoltaic solar cells using a novel alkaline-based approach that improves polishing efficiency and reduces environmental impact. The process involves removing the back surface of the silicon substrate through a pretreatment step, followed by etching using a potassium hydroxide solution. The alkaline solution enhances the etching process by creating a more uniform and controlled chemical environment, resulting in superior polishing characteristics that enhance long-wave absorption in photovoltaic cells.

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Vapor-phase etching and texturing of polycrystalline silicon wafers for solar cells using chemical reactions between corrosive gases and silicon. The method enables high-quality etching and texturing of polycrystalline silicon wafers through chemical reactions, achieving better than current mixed acid solution etching and superior anti-reflective properties. The process eliminates the need for expensive and complex RIE technology, while providing precise control over surface texture and anti-reflectivity.

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A method for forming a low-resistance back contact electrode in CdTe solar cells through controlled etching of the semiconductor surface. The method involves applying a chemically active material to the CdTe layer surface, activating it to etch the surface, and then removing the material to expose the semiconductor surface. A metal contact layer is then deposited on the etched surface, providing a durable and low-resistance back contact for CdTe solar cells.

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Chemical etching method for recycling solar cells that enables efficient reuse of the wafer without creating grooves. The method employs a single-step process combining phosphoric acid etching of the anti-reflection coating on the front side of the solar cell with aluminum removal on the rear side. This approach eliminates the need for separate etching steps for the front side and rear side components, while maintaining the wafer's original thickness. The etching process involves a temperature-dependent phosphoric acid solution with a concentration range of 85-95% and a temperature range of 160-180°C. The solution is mixed with a nitric acid and hydrofluoric acid ratio of 4:1. This single-step process enables the efficient removal of the front side anti-reflection coating while preserving the rear side aluminum structure, resulting in a wafer with a smooth surface without grooves.

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A method for enhancing solar cell efficiency through controlled etching of crystalline silicon substrates using microwave-assisted vapor etching. The process involves generating steam vapor through microwave heating, which is then used to vaporize etching solution containing nitric acid and hydrofluoric acid. The vaporized solution is directed through silicon fluoride membranes to etch the substrate surface, creating a thin film that enhances reflectance reduction and doping efficiency. The process enables precise control over etching conditions through microwave vapor generation, allowing for optimized etching parameters while minimizing solution waste.

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A method for preparing a monocrystalline silicon wafer surface without mask reactive ion etching, achieved through a novel gas composition. The method employs a CF-O2-SF gas mixture in the etching process, where CF4 and SF6 are mixed with oxygen to create a plasma that selectively etches silicon surfaces. The CF4 and SF6 are ionized through radio frequency power in the reflection chamber, generating plasma that selectively attacks the silicon surface. This approach enables precise control over etching conditions without the need for mask-based etching, allowing for high-performance etching of monocrystalline silicon surfaces.

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Surface texturing method for solar cells and Great Wall solar cell substrates that enhances light absorption by creating a structured surface morphology. The method employs chemical vapor etching using a combination of HF and HNO3 etchants, with the etchant concentration optimized for single crystal silicon. The etching process creates a series of interconnected trenches that form a structured Great Wall pattern, with each trench positioned between adjacent trenches. This unique morphology enhances light trapping by maximizing the surface area of the solar cell while minimizing reflection losses. The etching process can be repeated multiple times to achieve optimal structural integrity and light absorption efficiency.

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Solar cell texturing using ion implantation to create a pyramidal structure by selectively implanting hydrogen ions in a silicon wafer. The implantation pattern, determined by the wafer's surface orientation and implantation direction, creates a controlled crack structure that propagates along the wafer surface. This crack structure, with its characteristic pyramidal shape, enhances the solar cell's light absorption efficiency while minimizing defects.

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A rie device for etching silicon wafers in solar cell manufacturing that enables precise control and flexibility. The device features a reaction chamber with a gas tube and reactive ion baffle plate, where the gas flows through the tube and enters the chamber. A flow controller regulates the gas flow. On the wafer surface, a reaction ion baffle plate is positioned to control the etching process. This design allows precise control over the etching process while maintaining the wafer's surface integrity, particularly in critical areas like the front face of the solar cell.

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A method for manufacturing solar cells with local back surface field (LBSF) that achieves selective edge insulation while maintaining surface quality. The method employs an alkaline etching paste to create a textured surface on the back face, followed by an acid etching step specifically targeting the silicon layer. This selective etching enables precise edge insulation without damaging the silicon surface. The process combines the benefits of local back surface field technology with conventional edge insulation techniques, reducing manufacturing complexity and environmental impact.

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A method for silicon wafer solar cell fabrication that integrates parasitic junction removal and emitter etch-back into a single process. The method employs a KOH—NaOCl solution for both etch-back and polishing, which simultaneously removes parasitic junctions while maintaining conformal etch-back on doped surfaces and non-conformal polishing on undoped surfaces. This integrated solution enables a streamlined process sequence with only four steps, including parasitic junction removal, emitter etch-back, polishing, and rear-side processing.

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A method for creating high-quality solar cells with improved surface properties through a single-step process. The method involves etching a silicon wafer surface with an acidic etchant, followed by a passivation layer deposition. The acidic etchant selectively removes contaminants while preserving the underlying wafer surface, enabling a single-step process that eliminates the need for additional cleaning steps. The passivation layer is then applied to the wafer surface, followed by laser patterning for local contact structures. This approach preserves the wafer's native surface characteristics while achieving the desired surface texture and passivation properties.

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A solar battery system for reaction ion etching (RIE) processes in semiconductor manufacturing that improves efficiency and reliability. The system comprises an electrode plate gas system and a radio frequency power source, with the electrode plate containing an anode and cathode. The cathode is connected to the RF power source, which generates the etching gas while a protective gas is introduced into the system. This configuration enables the production of both etching gas and protective gas simultaneously, thereby enhancing the etching process while maintaining safety.

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