Current and future low-k dielectrics for Cu interconnects

Low-k/Cu integration with low-cost process is a key to future multilevel Cu damascene. This paper describes current status and future direction of low-k dielectrics for Cu interconnects. A novel direct patterning of low-k dielectric films by photochemical reaction is proposed as a future low cost multilevel interconnect technology. It is demonstrated that the smallest feature size of 50 nm damascene lines and via holes can be directly patterned in methylsilsesquiazane low-k dielectric films by electron beam lithography for the first time. In addition, a porous methylsilsesquiazane film is developed and evaluated as a candidate for future ultra-low-k dielectrics.