Integration Of Ultra-low-k Xerogel Gapfill Dielectric For high Performance Sub-o.18 /spl mu/m Interconnects

Abstract

Results and Discussion Xerogel exhibits several attractive features as an interlayer dielectric (ILD) film. The dielectric constant is very low (k-1.1 2.0) and can be tailored by altering the inherent porosity. The SiOz based chemical nature is appealing in that it is familiar to the IC community and represents a logical extension of existing SiOz and SOG materials with thermal stability above 500 C and a low coefficient of thermal expansion. However, integration of xerogels is thought to be ]problematic due to its porosity and poor mechanical stability. This work reports the first successful integration of xerogel dielectrics into CMP-planarized, double level metal (DLM) structures. These xerogel structures exhibited a 14% total capacitance reduction compared to comparable low-k hydrogen silsesquioxane (HSQ) gapfill structures with both better electromigration reliability and lower leakage. Both ForceFillhigh pressure A1 extrusion and W plug via processes were successfully integrated.