In the fabrication of 40nm BSI CMOS Image Sensors, the bond pad stack commonly consists of a top barrier, a main aluminum (Al) layer, and a bottom barrier A1.Following the Metal 7 Bond Pad photolithography step, this specific Ta-Barrier etch acts as the top layer breakthrough process P3.Its primary function is to accurately transfer the photoresist pattern into the top tantalum (Ta) or tantalum nitride (TaN) anti-reflective and protective capping layer, thereby exposing the underlying Al for the