Reliability and performance of submicron LDD NMOSFET´s with buried As n-impurity profiles

The reliability and performance of submicron LDD NMOSFET\´s with retrograde Arsenic impurity profiles in the n^-region were investigated. These structures were compared to devices with conventional As drains and phosphorus-implanted (P⁺) LDD\´s. Reduced substrate current was expected from 2D simulation and was confirmed experimentally. Lifetime under DC stress was improved by a factor of 15 over that observed for LDD devices. Transconductance was 93% of a conventional NMOSFET and 5% greater than a LDD FET having a P⁺implant of cm^-2, CMOS ring oscillator stage delay was equal to or better than the delay for LDD and conventional NMOSFET\´s and depicted a tradeoff between gmand gate-drain overlap capacitance Cdg. Short channel effects were evaluated for Leffdown to 0.45 µm and found to be similar to standard LDD designs.