High-resolution THZ imaging for optimized polysi patterning process

We present new ways to characterize, analyze and improve the patterning process of doped polysilicon (polySi) for application as passivating contacts for 6’’ high-efficiency bifacial cells and interdigitated back contact (IBC) cells. Combined with standard characterization techniques, non-destructive sheet resistance mapping with ultrahigh resolution using THz imaging allows us to understand p+polySi patterning issues. We propose a reliable, high-quality patterning process that provides firing-stable surface passivation. Such passivation levels are suitable for application in several high-efficiency cell concepts, including IBC cells with polySi passivating contacts.