An embodiment of the invention shows a process to form a damascene opening
preferably without hardmask overhang or dielectric layer undercut/void.
The low-k dielectric material can be sandwiched in two hardmask films to
form the dielectric film through which an interconnect opening is etched.
A first example embodiment comprises the following. We form a lower
interconnect and an insulating layer over a semiconductor structure. We
form a first hardmask a dielectric layer, and a second hardmask layer,
over the lower interconnect and insulating layer. We etch a first
interconnect opening in the first hardmask, the dielectric layer and the
second hardmask layer. Lastly, we form an interconnect in the first
interconnect opening.