The METAL 2 TRENCH - Photo step is a critical back-end-of-line (BEOL) lithography process that defines the lateral routing structures for the second metal layer A1.T1 Prior to this step, the V1 vias were etched into the inter-layer dielectric (ILD), establishing a via-first dual-damascene integration scheme.P2 Unlike Frontside Deep Trench or STI photo steps that pattern bulk silicon for isolation, or Metal 0/1 steps that interface directly with the sensitive device contact levels, the Metal 2 st