In the 40nm BSI CMOS Image Sensor flow, the bond pad opening module must establish electrical access to the embedded metal routing (Engineering Practice).Following the etching of the bulk silicon and pad oxide, the CESL 1 Etch step removes the first contact etch stop layer encountered in the backside dielectric stack A1.The CESL is typically composed of plasma-enhanced chemical vapor deposited (PECVD) amorphous hydrogenated silicon nitride P1.Because the BSI pad opening requires penetrating mult