Following the MET2 ILD oxide etch and the subsequent ashing and strip/clean processes, the M2 trenches and vias are fully open and exposed (Engineering Practice).The Ta-based liner deposition step is inserted here to coat the exposed inter-metal dielectric (IMD) and the underlying metal layer before copper metallization P2.This liner serves a dual purpose: it acts as a robust barrier against copper diffusion into the dielectric, and it provides an adhesion layer for the subsequent copper seed de