Wet chemical processing for c-Si solar cells - status and perspectives
Wet chemical processes are widely used within crystalline silicon solar cell production, mainly for surface texturing and cleaning purposes. Whereas research has been focusing mainly on process development in the past, only little progress could be observed in terms of process control techniques. Within the paper current state-ofthe- art wet chemical production processes are discussed and process control and quality assurance procedures (chemical, optical and electrical characterization of the wafers) are proposed. Purpose of the advanced characterization techniques is an enhancement of the process quality as well as an increase in high quality production yield. Further on, future industrial high efficiency cell processing necessitates cost effective, high quality cleaning processes especially prior to any surface passivation step. Starting from the well known semiconductor cleaning sequences, the paper motivates process simplifications and adaptations suitable for PV mass production.