Extremely Low Keff (1.9) Cu Interconnects with Air Gap Formed Using SiOC

Abstract

Dual damascene Cu interconnects with Keff below 2.0 have been demonstrated for the first time. Air gaps between Cu lines were formed with a low K SiOC film in a carefully designed manner. CoWP cap layers were introduced to protect the Cu lines and to eliminate a dielectric liner layer. In addition, AGE (Air Gap Exclusion) was applied to solve crucial problems related to the air gaps. Keff of 1.9 was obtained at 65nm design rule, which surpassed by far ITRS target (2.52.8) for hp45. It was also confirmed that leakage current between lines was suppressed by the formation of the air gaps.