Following the P-Pinning IIP step, the photoresist pattern used as an ion implantation blocking mask must be completely removed A5.This critical strip and clean sequence prepares the wafer for the subsequent P+ VSS and Periphery P-Well Contact IIP photolithography step (Engineering Practice).The upstream P-pinning implant is fundamentally responsible for introducing a heavily doped p+ layer at the Si-SiO₂ interface, which starves the interface states of electrons and suppresses dark current P1.An