Ultra-thin decoupled plasma nitridation (DPN) oxynitride gate dielectric for 80-nm advanced technology

Balancing gate leakage reduction, device performance, and gate dielectric reliability is a major challenge for oxynitride used as a gate dielectric for advanced technology. As compared to RTONO oxynitride, pMOSFET threshold voltage shift and transconductance degradation have been problematic for devices using remote plasma nitridation (RPN) or decoupled plasma nitridation (DPN) process due to non-optimal nitrogen profile in the film. In this paper, we report that the nitrogen profile of DPN gate dielectric can be engineered primarily,by tuning the plasma pressure after optimizing other DPN process parameters to solve these problems. An EOT of 15 Angstrom (23-Angstrom NMOS CETinv) DPN oxynitride is demonstrated to have an acceptable pMOS Vt, comparable transconductance, significantly (similar to30x) longer pMOS time-to-breakdown reliability for packaged devices, and 5 x gate leakage reduction relative to a high quality RTONO used in industry. The high quality ultrathin DPN film is fabricated in a commercially available system, which is compatible with standard CMOS processing technology. These encouraging results make high-pressure DPN oxynitride an attractive gate dielectric candidate for 80-nm advanced technology and beyond.