A 0.5 μm fully scaled two-level metal fully planarized interconnect structure fabricated with X-ray lithography

A fully planarized two-level-metal structure has been successfully fabricated at 0.5 μm groundrules with the use of X-ray lithography at all processing levels. A 0.5-μm minimum feature size was required for all levels, including the second-level metal. Planarized PECVD oxide and PECVD nitride were employed as dual dielectric layers below M1 and M2. Chemical vapor deposition (CVD) W studs formed by W etchback served as vertical connections for interlevel vias and contacts. All ten lithography patterning steps were performed with X-ray exposures to determine what possible implications this emerging technology might have on the implementation of the interconnect levels