Removal of metal cusp for improved contact fill

Abstract

Disclosed is a method for providing improved step coverage of contacts with conductive materials, and particularly metals. An initial conductive layer is deposited over an insulating layer either before or after contact opening formation. The deposition process tends to block the contact mouth with a metal overhang, or cusp. After both conductive layer deposition and contact formation a portion of the initial conductive layer is removed, thus removing at least a portion of the metal cusp and opening the contact mouth for further depositions. The invention has particular utility in connection with formation of metal plugs in high-aspect ratio contacts. Embodiments are disclosed wherein the cusp removal comprises mechanical planarization, etching with high viscosity chemicals, and facet etching.

Dependencies are inferred from the claim text.