Dissolvable dielectric method and structure

摘要

A fabrication process is provided that produces an air gap dielectric in which a multi-level interconnect structure is formed upon a temporary supporting material. The temporary material is subsequently dissolved away leaving behind an intralevel and an interlevel dielectric comprised of air. In one embodiment of the invention, a first interconnect level is formed on a barrier layer. A temporary support material is then formed over the first interconnect level and a second level of interconnect is formed on the temporary support material. Prior to formation of the second interconnect level, a plurality of pillar openings are formed in the temporary material and filled with a conductive material. In addition to providing a contact between the first and second level of interconnects, the pillars provide mechanical support for the second interconnect level. The temporary material is dissolved in a solution that attacks the temporary material but leaves the interconnect material and pillar material intact. In one embodiment of the invention, a passivation layer is formed on the second interconnect level prior to dissolving the temporary material. The air gap dielectric can be used with more than two levels of interconnect, if desired.