Plasma Etching Techniques for Solar Cell Production

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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Plasma etching method using heptafluoropropyl methyl ether (HFE-347mcc3) and heptafluoroisopropyl methyl ether (HFE-347mmy) as etchant gases, achieving high aspect ratio etching while maintaining selectivity. The method employs a bias voltage-controlled plasma environment, where the etchant gas mixture is supplied to the plasma chamber along with argon gas. The HFE-347mcc3 and HFE-347mmy mixtures are vaporized and introduced into the plasma chamber, where they interact with the plasma to enhance etching performance. The etching process enables the formation of high-aspect-ratio structures through anisotropic etching, with improved selectivity compared to conventional fluorocarbon-based etching methods.

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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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Selective etching of silicon oxide films using a plasma etching process that combines a fluorocarbon gas with an oxidant like oxygen. The process employs a halogenated hydrocarbon gas and a C4F6O3 gas in a controlled ratio, with the fluorocarbon gas forming active species in the plasma while the oxidant provides reactive oxygen species. This dual-gas approach enables precise control of sidewall etch rates while maintaining selective etching of the silicon oxide film.

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Method to improve the efficiency of heterojunction solar cells by treating the intrinsic amorphous silicon (a-Si) layer with hydrogen plasma multiple times during deposition. After forming each layer of a-Si, hydrogen plasma treatment is performed before continuing with the next layer. This step is repeated multiple times during the deposition of the entire a-Si stack. The hydrogen plasma treatment improves carrier transport in the a-Si layers, which increases solar cell efficiency.

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Etching silicon-based films using a novel plasma-enhanced etching process that combines multiple etching cycles with plasma treatment. The process involves preparing a substrate with the target film, then repeatedly applying etchant gas followed by plasma treatment to expose the substrate. This approach enhances etch uniformity and surface quality by addressing the film's chemical and physical properties.

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Copper seed layer processing method and solar cell preparation method to improve the conductivity and tensile strength of copper electrode grid lines in solar cells. The method involves partially oxidizing the copper seed layer on the solar cell substrate before electroplating the copper grid lines. The oxidation is done using plasma treatment. This improves the contact between the copper grid and the seed layer, reducing defects and voids. It also reduces oxide formation during electroplating, which improves grid conductivity.

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Method to improve uniformity of plasma processing for semiconductor devices like solar cells. The method involves doping hydrogen gas into the plasma processing chamber during deposition of thin films like aluminum oxide. The hydrogen improves thickness uniformity of the deposited film across the wafer. It can be added as an auxiliary gas along with the reactant and carrier gases. The hydrogen can be in excited state provided by a remote plasma generator.

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A plasma etching method for high-aspect-ratio silicon structures using a fluorocarbon-free etchant. The method employs a mixed gas containing argon and 1,1,2,2-tetrafluoroethylenetriethanol as the etchant, which achieves superior etching characteristics compared to conventional perfluorocarbon-based etchants. The etchant is generated through a plasma process where the mixed gas is introduced into a plasma chamber containing an etchant source. The plasma etching process enables the formation of high-aspect-ratio structures with minimal fluorocarbon film deposition, while maintaining high etch rates and selectivity.

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Plasma etching method using pentafluoropropanol (PFP) with low global warming potential, replacing conventional perfluorocarbon (PFC) gas. The method employs a PFP/argon gas mixture in an etching chamber, where the PFP vaporizes and generates plasma. The plasma density is enhanced through electropositive Ar addition, enabling isotropic etching of target surfaces. The PFP/argon mixture maintains a controlled ratio of 2:3 to 1:9, ensuring optimal etching conditions for silicon oxide thin films.

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Selective plasma etching of silicon oxide films using a novel gas mixture that improves etch selectivity and prevents shoulder collapse in spacers. The method employs a fluorocarbon-hydrofluoric acid gas mixture for plasma etching, with specific ratios of fluorocarbon and hydrofluoric acid gases. The fluorocarbon gas enhances surface passivation, while the hydrofluoric acid gas selectively etches the silicon oxide film. The fluorocarbon-hydrofluoric acid gas mixture provides superior etch selectivity compared to conventional fluorocarbon-hydrofluoric acid gas mixtures, particularly in the critical shoulder region of spacers. This approach enables reliable etching of silicon oxide films without compromising spacer integrity.

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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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Plasma etching method using a low-GWP etchant that enables high aspect ratio etching in semiconductor devices. The method employs a hydrofluoroether gas, HFE-347, with a global warming potential (GWP) lower than traditional perfluorocarbon (PFC) gases. The etchant is supplied in a mixed gas composition of 3:2 to 1:4 heptafluoroisopropyl methyl ether (CF3CH(CH2)2CH2OEt) and argon, with flow rates in the 9:1 to 7:3 ratio. The etchant selectively etches silicon oxide or silicon nitride structures with diameters greater than 10 times their depths, enabling the formation of high-aspect-ratio holes.

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Etching of silicon-based films using a novel plasma etching process that enhances selectivity through controlled fluorine incorporation. The process employs a temperature-controlled plasma etching environment where the substrate temperature is maintained below -40°C. This temperature condition enables the formation of a plasma containing hydrogen and fluorine, which selectively etches silicon-based films while selectively degrading fluorine-containing compounds. The plasma composition can be optimized to achieve improved selectivity between silicon oxide and silicon films.

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Plasma etching method using perfluoropropylcarbinol (PPC) as a low-GWP discharge gas for high-aspect-ratio silicon oxide structures. The method employs PPC as a precursor to form a stable gas phase, which enhances plasma density and surface chemistry. PPC vaporizes in the chamber, generating a stable PPC-argon mixture that enables efficient etching of silicon oxide thin films through enhanced ion bombardment. The PPC-argon mixture is optimized with a flow ratio of 2:3 to 1:9, maintaining optimal etching conditions for high-aspect-ratio etching.

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Plasma etching method using PIPVE (perfluoroisopropyl vinyl ether) with low global warming potential for high-aspect-ratio silicon etching. The method employs a PIPVE vaporizer followed by a discharge gas containing the vaporized PIPVE and argon. The plasma is generated by applying a bias voltage to the substrate, with the PIPVE serving as a precursor to fluorine-containing species. The plasma etches the target material through ion bombardment, resulting in anisotropic etching with improved selectivity and uniformity compared to conventional PFC-based etching.

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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 optimizing heterojunction solar cells through controlled hydrogen plasma treatment during thin film deposition. The process involves plasma etching the intrinsic silicon layer before deposition of the conductive silicon layer, followed by hydrogen plasma treatment during film formation. This approach enables precise control over film thickness variations during deposition, which can lead to improved conversion characteristics and reduced batch-to-batch variability in solar cells.

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A method for achieving high-efficiency solar cells through a single-chamber process that eliminates interface contaminants. The method employs controlled plasma treatment of the photovoltaic unit's interface regions between layers, specifically the p-n junction interface. The treatment process selectively reacts with contaminants present at this interface, effectively removing them from the chamber while maintaining the unit's electrical performance. This approach enables the production of high-efficiency solar cells without the need for separate chamber cleaning steps, achieving comparable efficiency levels as conventional multi-chamber processes.

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Etching silicon-containing films using a plasma processing apparatus that employs a novel fluorine-based gas mixture. The apparatus generates plasma through a CF4-H2-IF6 mixture, which is supplemented with an additive gas containing fluorine. The CF4 component provides the base plasma, while the IF6 component enhances the etching process by reducing fluorine binding energy. This approach enables improved etching performance of silicon-containing films in plasma processing applications.

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