Following the sequential deposition of Ti for adhesion, TiN for a diffusion barrier, and bulk chemical vapor deposition (CVD) of Tungsten within the contact holes, the resulting structure exhibits significant metallic overburden and surface topography P2.The Tungsten Chemical Mechanical Planarization (W CMP) step exists to globally planarize the wafer surface by removing this bulk W overburden, physically isolating individual contact plugs prior to the subsequent barrier TiN/Ti CMP and cleaning