High-density high-reliability tungsten interconnection by filled interconnect groove metallization

A novel multilevel metallization scheme has been developed that uses tungsten for the primary level of interconnection. Grooves that are 1-μm wide and 2.0-μm deep, corresponding to a level of line conductor interconnection, are pattern-etched into a planar layer of oxide dielectric. They are filled by isotropically depositing a blanket layer of pure tungsten using low-pressure chemical vapor deposition (CVD), followed by etch-back of the tungsten to produce a filled-interconnection-groove (FIG) conductor structure. Fabricated FIG conductors display an average sheet resistivity of 48 mΩ/square, comparable to conventional aluminum conductors. In addition, FIG metallization provides excellent planarity and greatly improved electromigration strength, and it facilitates the use of stacked vias