In the 40nm BSI CMOS Image Sensor flow, the final Ashing & Strip/Clean step follows the Bond Pad Metal 7 Barrier Etch to comprehensively remove highly crosslinked photoresist and post-etch residues P1. During the preceding barrier etch, halogen-based plasmas interact with the Ta/TaN barrier and underlying copper to generate complex fluorocarbon polymers and organometallic byproducts A2. If left untreated, these residues form a highly resistive interfacial layer that severely degrades the specifi