Interconnect structure having large self-aligned vias

Abstract

A wavy line interconnect structure that accommodates small metal lines and enlarged diameter vias is disclosed. The enlarged diameter vias can be formed using a self-aligned dual damascene process without the need for a separate via lithography mask. The enlarged diameter vias make direct contact with at least three sides of the underlying metal lines, and can be aligned asymmetrically with respect to the metal line to increase the packing density of the metal pattern. The resulting vias have an aspect ratio that is relatively easy to fill, while the larger via footprint provides low via resistance. An interconnect structure having enlarged diameter vias can also feature air gaps to reduce the chance of dielectric breakdown. By allowing the via footprint to exceed the minimum size of the metal line width, a path is cleared for further process generations to continue shrinking metal lines to dimensions below 10 nm.