Method to form interconnect structure with tungsten fill

Abstract

Aspects of the present disclosure include a method for forming a contact on a semiconductor device, the semiconductor device including a conductive region disposed over a substrate, the method comprising: depositing a dielectric material on the substrate; forming an opening in the dielectric material to expose the conductive region; forming a barrier layer on a lower surface and sidewalls of the opening in the dielectric material, the barrier layer terminating below an upper surface of the dielectric material and surrounding a lower portion of the opening; depositing cobalt in the lower portion of the opening, the cobalt terminating at an upper surface of the barrier layer; depositing tungsten to fill the opening to at least the upper surface of the dielectric material; and planarizing the upper surface of the dielectric material with the tungsten in the opening.