In 40nm Back-Side Illuminated (BSI) CMOS Image Sensor technology, minimizing optical and electrical crosstalk is critical, often necessitating complex light shield grid structures P4.The Optical Pad 1 Deposition step occurs immediately following the tungsten (W) and titanium nitride (TiN) etch and subsequent strip processes in the light shield (LS) grid module A1.Its primary function is to serve as the foundational layer of a multi-film dielectric stack that will eventually act as a hard mask an