This specific Ashing & Strip/Clean step immediately follows the intermediate N-type Floating Diffusion (NFD) ion implantation in the shared-pixel architecture A3.During the preceding implant, the photoresist (PR) layer blocking the transfer gates and photodiode regions absorbs high-energy n-type dopants, transforming its upper layer into a highly crosslinked, carbonized crust known as high-dose ion-implanted photoresist (HDI-PR) P1.This hardened mask must be entirely eradicated before the subseq