Dynamic-stress-induced enhanced degradation of 1/f noise in n-MOSFET's

AC-stress-induced degradation of 1/f noise is investigated for n-MOSFET's w ith thermal oxide or nitrided oxide as gate dielectric, and the physical me chanisms involved are analyzed. It is found that the degradation of 1/f noi se under ac stress is far more serious than that under de stress, For an ac stress of V-G = 0 similar to 0.5 V-D, generations of both interface states (Delta D-it) and neutral electron traps (Delta N-et) are responsible for t he increase of 1/f noise, with the former being dominant. For another ac st ress of V-G = 0 similar to V-D, a large increase of 1/f noise is observed f or the thermal-oxide device, and is attributed to enhanced Delta N-et and g eneration of another specie of electron traps, plus a small amount of Delta D-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 conside rably improved oxide/Si interface and near-interface oxide qualities associ ated with interfacial nitrogen incorporation.