The backside of a BSI CMOS image sensor incorporates complex dielectric architectures to optimize optical transmission and carrier collection, governed by the absorption properties of the semiconductor T1.Following the initial Bond Pad Opening 1 which partially clears the upper organic layers, the Bond Pad Opening 2 - Photo step defines the precise lithographic mask required to pattern the remaining underlying barrier films, such as the upper grid seal and lower OCL coatings A2.This step is dist