The P-Pinning Ion Implantation (IIP) step is critical for forming the surface P+ layer of the Pinned Photodiode (PPD) in a CMOS image sensor P1.Following the N-type photodiode (PD) and floating diffusion (FD) implants, this step introduces a shallow, heavily doped p-type layer directly at the silicon surface T3.The primary function of this layer is to physically separate the n-type charge storage region from the Si-SiO2 interface P1.By maintaining a high surface hole concentration, this structur