By Kris Baert, Program Manager of Si Solar Cells in the Photovoltaics Department, IMEC; Paul W. Mertens, Ultra Clean Processing Expertise Centre Leader, IMEC; Twan Bearda, Photovoltaics Division, IMEC
Wet processing can be a very high performing and cost-effective manufacturing process. It is therefore extensively used in Si solar cell fabrication for saw damage removal, surface texturing, cleaning, etching of parasitic junctions and doped oxide glass. PV manufacturers have succeeded in bringing down the cost of ownership of batch-type and in-line tools. The trend to back-side passivated solar cells requires cost-effective single-sided processing solutions. With the future pointing to ever-thinner silicon solar cells, handling these thin wafers in wet environments is a major challenge for any wet process. This paper reviews the major wet processing steps, emphasising some new developments and unknown issues, and provides a more general outlook on trends in wet processing.