In the 40nm BEOL integration flow, this specific Ashing & Strip/Clean step immediately follows the ILD 1-1 SiCN Etch that exposes the underlying Metal 1 (M1) copper P3.During the preceding fluorocarbon-based plasma etch, highly crosslinked fluoropolymer residues are intentionally deposited on the dielectric sidewalls to ensure etching anisotropy and profile control P1.However, these post-plasma etch residues, along with any remaining photoresist and sputtered copper species from the exposed M1,