Performance and Reliability of Strained-Silicon nMOSFETs With SiN Cap Layer

A complete comparison of performance and reliability between polysilicon gate/SiON oxide nMOSFETs with and without SiN cap layer is presented. The uniaxial tensile strain induced by the cap layer causes an improvement in the channel current drive capability without degrading the noise performance. The gain in the transconductance, for the strained devices, was found to decrease for increasing channel lengths and for higher channel fields. Similar robustness against hot carrier stress, bias-temperature instability, and time to breakdown were found between strained and unstrained-silicon devices, confirming the advantages of strain technology