By Jochen Rentsch, Head of the Wet Chemical and Plasma Technologies, Fraunhofer ISE; Rupprecht Ackermann, Department of Wet Chemical and Plasma Technologies, Fraunhofer ISE; Gero Kästner, Department of Wet Chemical and Plasma Technologies, Fraunhofer ISE; Christoph Schwab, Department for Wet Chemical and Plasma Technologies, Fraunhofer ISE; Martin Zimmer, Department for Wet Chemical and Plasma Technologies, Fraunhofer ISE,; Ralf Preu, Director of the Division for PV Production Technology and Quality Assurance, Fraunhofer ISE
Wet chemical process equipment is widely used in industrial solar cell production, and inline etching systems in particular have attracted more and more attention since their introduction 10 years ago. The horizontal wafer transport within these systems has made it possible to think about single-side wafer treatments even for wet chemical process applications. Since its market introduction in 2004, the chemical edge isolation process based on the single-side removal of the parasitic emitter at the rear side of the solar cells has gained an increasing share of the market in comparison to competing technologies that use laser techniques. However, stabilization and control of such a process under mass production conditions remains challenging. The introduction of new high-efficiency cell concepts involving passivated rear sides will increase the importance of single-side wafer treatments, as the final solar cell performance is significantly affected not only by the complete removal of the parasitic emitter but also by an ideally polished surface on the rear side of the wafer.
