The RIE etch ILD 3-1 Etch is a critical subtractive process within the BONDPAD module of the 40nm BSI CMOS Image Sensor packaging flow P1.Following the sequential ILD 1 and 2 etches, this step removes the bulk of the thick upper interconnect-level dielectric layer to expose the top-level metal (Metal 7) for subsequent wire bonding or bump formation A2.Unlike shallow oxide hard mask etches or isotropic wet nitride removals, this step requires highly anisotropic deep etching through thick dielectr