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2005
Conference Paper
Titel
Industrialisation of dry phosphorus silicate glass etching and edge isolation for crystalline silicon solar cells
Abstract
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. Additional to PSG etching, the emitter layer at the rear side of the solar cell can be removed simultaneously. In this paper we present a process sequence which meets all this requirements. With an etch gas mixture containing CF(ind 4) and H(ind 2) high PSG to Si selectivities together with high etch rates could be reached enabling short process times on a dynamic in-line plasma etching system. A plasma post cleaning step ensures a clean and well conditioned surface for the subsequent SiNx deposition. The dry PSG etching and cleaning can be integrated together with a rear emitter removal and PECVD deposition step to a vacuum process cluster after emitter diffusion effectively reducing overall production costs. The environmental impact of the used etch gases can be kept low due to a high gas utilization as well as an effective waste gas abatement.