Dry Phosphorus silicate glass etching and surface conditioning and cleaning for multi-crystalline silicon solar cell processing (original) (raw)
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Dry Phosphorus Silicate Glass Etching for Crystalline Si Solar Cells
Dry plasma etching techniques could be of permanent importance in future complete in-line fabrication of crystalline silicon solar cells. Phosphorus silicate glass (PSG) etching represents the most challenging process step, since it has to be etched fast and residual free, without damaging the underlying emitter layer. In this paper we present a process sequence which meets all this requirements. With different CF-containing etch gas mixtures high SiO 2 to Si selectivities together with high etch rates could be reached enabling short process times. A plasma post cleaning step ensures a clean and well conditioned surface for the subsequent SiN x deposition. Dry PSG etched solar cells reached efficiencies of 14.6 % on mc-Si and 15 % on Cz-Si, having similar or even better performance in all solar cell parameters compared to wet chemically PSG etched reference cells. Upscaling of the selective etching processes to an industrially suitable in-line etching system with high wafer throughp...
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This paper gives an overview on the standard crystalline silicon solar cell manufacturing processes typically applied in industry. Main focus has been put on plasma processes which can replace existing, mainly wet chemical processes within the standard process flow. Finally, additional plasma processes are presented which are suited for higher-efficient solar cells, i.e. for the "passivated emitter and rear cell" concept (PERC) or the "heterojunction with intrinsic thin layer" approach (HIT). Plasma processes for the deposition of thin dielectric or semiconducting layers for surface passivation, emitter deposition or antireflective coating purposes are presented. Plasma etching processes for the removal of phosphorus silicate glass or parasitic emitters, for wafer cleaning and masked and mask-free surface texturisation are discussed.
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