The METAL 5 TRENCH - Photo step defines the spatial geometry for the fifth-level copper interconnect trenches within a via-first dual-damascene integration scheme P1.Positioned immediately after the Via 4 (V4) etch and clean processes, this lithography step patterns the photoresist to expose the underlying inter-level dielectric (ILD 4-2) for the subsequent trench etch A1.Unlike lower-level metal patterning (such as Metal 0 or Metal 1) which directly interfaces with densely packed front-end tran