In the 40nm BSI CMOS image sensor flow, backside passivation is critical to reduce dark current and surface recombination at the thinned silicon interface T1.After the wafer undergoes backside thinning and oxide hard mask deposition, it must be prepared for the Backside Passivation Ion Implantation (IIP) photolithography step A1.This specific Pre Litho Cleaning step ensures the oxide hard mask surface is completely free of organic residues and inorganic contaminants before the photoresist is app