The "RIE etch ILD 3-2 Etch" step in the BONDPAD module of a 40nm BSI CMOS Image Sensor is a critical process used to expose the underlying metal pad for external electrical connection P3.Following the preliminary removal of upper dielectric layers in "ILD 3-1 Etch", this specific step completes the penetration through the remaining thick interlayer dielectric (ILD) to land precisely on the Bond Pad barrier P3.Unlike general oxide or nitride etches used in early device formation, this bond pad et