Advanced Direct-Polish Process on Organic Non-Porous Ultra Low-k Fluorocarbon Dielectric on Cu Interconnects

A direct-polish process has applied to the ultra low-k dielectric without the etch stop layer to reduce effective dielectric constant in damascene interconnects. In this study, the direct-polish process on organic non-porous dielectric, fluorocarbon (k=2.2), was demonstrated and an optimum direct-polish process condition was investigated. Mechanical effect, not chemical effect, on fluorocarbon degraded electrical properties by changing of chemical structure of fluorocarbon. A surface plasma treatment of fluorocarbon before polishing was applied to avoid the degradation of electrical characteristics during direct-polish and this result revealed that the surface plasma treatment of fluorocarbon is a practical technique in advanced Cu interconnects.