The ILD 1-2 Oxide Etch step is a critical back-end-of-line (BEOL) process designed to form the Metal 2 interconnect trenches within the interlayer dielectric P4.Following the Metal 2 photolithography and the preceding ILD 1-1 SiCN via/etch stop layer opening, this step subtractively defines the horizontal routing pathways for the subsequent Ta-based liner and copper seed deposition P1.Unlike front-end oxide etches (such as pad oxide or spacer etches) that interface directly with robust crystalli