Dynamic-stress-induced enhanced degradation of 1/f noise in n-MOSFETs

AC-stress-induced degradation of 1/f noise is investigated for n-MOSFETs with thermal oxide or nitrided oxide as gate dielectric, and the physical mechanisms involved are analyzed. It is found that the degradation of 1/f noise under AC stress is far more serious than that under DC stress. For an ac stress of V/sub G/=0/spl sim/0.5 V/sub D/, generations of both interface states (/spl Delta/D/sub it/) and neutral electron traps (/spl Delta/N/sub et/) are responsible for the increase of 1/f noise, with the former being dominant. For another AC stress of V/sub G/=0/spl sim/V/sub D/. a large increase of 1/f noise is observed for the thermal-oxide device, and is attributed to enhanced /spl Delta/N/sub et/ and generation of another specie of electron traps, plus a small amount of /spl Delta/D/sub it/. Moreover, under the two types of AC stress conditions, much smaller degradation of 1/f noise is observed for the nitrided device due to considerably improved oxide/Si interface and near-interface oxide qualities associated with interfacial nitrogen incorporation.