Tungsten stud process for stacked via applications

摘要

A tungsten stud, stacked via process, has been developed, featuring smooth planar topographies at all metal levels. The desirable topography is obtained by allowing the tungsten stud to reside at the same level, or slightly above the level, of the top surface of the via hole insulator. This is achieved via an insulator etch back procedure, performed after metal stud formation.