Interconnect and contact system for metal-gate MOS VLSI devices

Claim 1

A gate, contact and interconnect structure for an MOS integrated circuit, comprising: a metal gate on a face of a silicon body comprising a layer of tungsten overlying and adhered to a thin layer of silicon oxide, and a coating of oxide on the sidewalls of said gate totally encapsulating said gate; heavily-doped source/drain regions in said face self-aligned with said oxide on the sidewalls of the metal gate, a tungsten metal layer formed on the surface of said source/drain regions self-aligned with said oxide on the sidewalls of the metal gate, a thick deposited insulator coating on said face over said metal gate and over said tungsten metal layer and source/drain regions, a metal contact and interconnect strip extending along said face overlying said insulator coating and extending into a contact hole in said insulator coating to make electrical connection to said tungsten metal layer, and comprising: a thin layer of molybdenum over said insulator coating, a thicker layer of tungsten over said molybdenum, and a layer of gold over said thicker layer of tungsten.