In a 40nm Backside Illuminated (BSI) CMOS Image Sensor, exposing the bond pad or through-silicon via (TSV) landing pad from the backside requires etching through a highly complex, thick stack of dielectric materials A1.Following the sequential opening of the Pad Oxide and Contact Etch Stop Layers (CESL 1 and 2), the PMD 1 Etch initiates the bulk removal of the Pre-Metal Dielectric (PMD) stack P1.Because the total dielectric thickness in BSI architectures is substantial, the complete etch sequenc