This specific Ashing & Strip/Clean step immediately follows the high-dose P+ ion implantation used to form the VSS and Periphery P-Well contacts, and crucially prepares the wafer for the subsequent high-temperature Dopants Activation anneal A6.During the upstream implantation, the photoresist mask absorbs a massive flux of high-energy dopant ions, which physically damages the resist polymer chains and chemically depletes hydrogen to leave a highly cross-linked, carbonized surface crust A4.As not