Method to remove excess metal in the formation of damascene and dual interconnects

Abstract

A method of removing excess metal, particularly copper, in the fabrication of interconnects has been achieved. In accordance with the objects of this invention, a new method of removing excess metal in the formation of an interconnect has been achieved. A semiconductor substrate is provided. A dielectric layer is provided overlying the semiconductor substrate. Trenches are formed in this dielectric layer for planned damascene or dual damascene interconnects. A barrier layer is provided overlying the dielectric layer and lining the trenches. A metal layer is provided overlying the barrier layer and completely filling the trenches. A masking layer is deposited overlying the metal layer. The masking layer is patterned to form a mask that only overlies the trenches. The metal layer is etched down where not covered by the mask. This etching down is partial so that the barrier layer is not exposed. This etching down leaves the metal layer underlying the mask thicker than the metal layer not underlying the mask. The masking layer is etched away. The metal layer and the barrier layer are polished down to the top surface of the dielectric layer to form the planned interconnects, and the integrated circuit is completed.