Late-porogen removal integration for ultra-low-k{sub}(eff) IMDs

摘要

The value k{sub}(eff) has become a valuable metric for evaluating the quality of the final integrated intermetal dielectric (IMD) film stack. Achieving the ITRS projection of 2.5 k{sub}(eff) for interconnect dielectric by the end of the decade may require the integration of highly porous, ultra-low-k films. Moreover, integration must occur with minimal process-induced dielectric damage. To this end, a SEMATECH dual-damascene integration approach has been developed that entails stopless integration and a post-CMP, or "late," porogen-removal process. Low-damage CMP, etch, ash, and dielectric-cure processes were integrated to demonstrate an intraline k{sub}(eff) of 2.5. In addition, preliminary results show that a new spin-on dielectric with relatively higher-temperature stability can be integrated with a PECVD hard-mask for enhanced reliability, though with slightly higher integrated k{sub}(eff).