In the fabrication flow of a CMOS image sensor, the Pixel Array P-Well Ion Implantation (IIP) step immediately follows the N-Photocathode implants and associated photolithography P3.This step introduces p-type dopants to form the foundational well structures that house the pixel's active readout components, such as reset and source follower transistors T2.Crucially for active pixel sensors, the deep P-well establishes an electrostatic shielding layer between the P-type epitaxial layer and unrela