Qi Xiang

Polarity dependent reliability of advanced MOSFET using MOCVD nitrided Hf-silicate high-k gate dielectric

We report reliability of MOSFETs with MOCVD nitrided Hf-silicate (HfSiON) high-k gate dielectric. HfSiON has shown superior electrical characteristics, such as low leakage relative to SiO/sub 2/ and high mobility compared to other high-k gate dielectrics. SILC is found to be comparable to SiO/sub 2/ and better than Hf-silicate without nitridation. TDDB and BTI reveal significant difference between inversion and accumulation mode. Polarity-dependent charge trapping and defect generation are observed and attributed to asymmetric band diagram as well as dissimilar charging processes in two stress modes. Trap-assisted tunneling is evidenced by its strong temperature dependence. Charge pumping tests indicate higher interface density compared to SiO/sub 2//Si. The Weibull slope is determined to be about 3, showing robust wear-out quality of the high-k dielectric.

High performance ultra-thin silicon nitride gate dielectrics prepared by in-situ RTCVD techniques

Through the characterization of RTCVD process conditions, high performance CMOS devices based on silicon nitride stack gate dielectrics with 40 nm gate length were prepared. In sub 20 /spl Aring/ thick ultra-thin stack gate dielectrics approaching 12 /spl Aring/ of EOT, it was found that HF last cleaned dielectric layer shows slightly higher leakage current as compared to the conventional RCA cleaned dielectric layer. It may be due to thinner dielectric properties on HF last cleaned surfaces. It was also found that annealing with NO, N/sub 2/O and N/sub 2/ modifies the bonding structure of silicon nitride stack layers and significantly improved the properties of ultra-thin stack gate dielectrics.