Turn-On Voltage Degradation of Short Channel MOSFETs Due to Generation of Interface States

For scaled Mos devices long term reliability of the turn-on voltage is important. Longterm stability of the turn-on voltage has been measured under stress aging for 2000 h (T=150°C. E=2.5×106V/cm). Generation of interface traps without essential flatband shift is observed. Despite that, positive turn-on voltage shift appears for effective channel lengths L<2.0μm. The stress measurements have been performed on multitransistor structures which permit to measure interface traps, threshold voltage, and feature sizes on the same test structure. The relationship between the turn-on voltage shift and the interface trap density is discussed with respect to the effective channel length.