In the 40nm Backside Illuminated (BSI) CMOS Image Sensor process flow, the light shield (LS) and aperture grid restrict optical crosstalk between adjacent pixels (Engineering Practice).Following the deposition of the barrier and bulk grid metal, the Oxide Grid Seal Layer is deposited directly onto the continuous metal stack (Engineering Practice).Because the process flow proceeds next to photoresist application and then Oxide Grid Seal Layer Etch, this oxide primarily serves as a dielectric hard