Following the PMD oxide etch and subsequent clean processes, the Ta-based liner deposition serves as the foundational barrier layer for the Metal 1 (MET1) copper interconnect P3.Copper is utilized as the primary conductor in modern interconnects due to its low resistivity, but its high diffusivity dictates that it will drift or diffuse into the surrounding dielectric without a conformal barrier, leading to catastrophic circuit shorting P3.To mitigate this, a Ta-based stack—typically consisting o