Stacked via-stud with improved reliability in copper metallurgy

Abstract

A multilevel semiconductor integrated circuit (IC) structure including a first interconnect level including a layer of dielectric material over a semiconductor substrate, the layer of dielectric material comprising a dense material for passivating semiconductor devices and local interconnects underneath; multiple interconnect layers of dielectric material formed above the layer of dense dielectric material, each layer of dielectric material including at least a layer of low-k dielectric material; and, a set of stacked via-studs in the low-k dielectric material layers, each of said set of stacked via studs interconnecting one or more patterned conductive structures, a conductive structure including a cantilever formed in the low-k dielectric material. The dielectric layer of each of the multiple interconnection levels includes a soft low-k dielectric material, wherein the cantilever and set of stacked via-studs are integrated within the soft low-k dielectric material to increase resistance to thermal fatigue crack formation. In one embodiment, each of the set of stacked via-studs in the low-k dielectric material layers is provided with a cantilever, such that the cantilevers are interwoven by connecting a cantilever on one level to a bulk portion of the conductor line on adjacent levels of interconnection, thereby increasing flexibility of stacked via-studs between interconnection levels.