After the planarization of tungsten and Ti/TiN contact plugs via CMP, the Metal 0 (M0) W Deposition step establishes the first local interconnect layer in the 40nm BEOL flow P1.M0 serves as the critical bridge linking high-aspect-ratio contact plugs to the subsequent global routing layers A2.Unlike the Metal 1 through Metal 4 steps in this flow, which utilize copper electroplating within a dual-damascene architecture P2, this M0 step employs blanket tungsten deposition followed by subtractive pa