A NEW ASSESSMENT OF THE SELF-LIMITING HOT-CARRIER DEGRADATION IN LDD NMOSFETS BY CHARGE-PUMPING MEASUREMENT

By progressively lowering the gate-base level in the charge pumping (C P) measurement, the channel accumulation layer is caused to advance in to the LDD gate-drain overlap and spacer-oxide regions, extending the interface that can be probed. This constitutes the basis of a new tech nique that separates the hot-carrier-induced interface states in the r espective regions. Linear drain current degradation, measured at low a nd high gate bias, provides clear evidence that interface state genera tion initiates in the spacer region and progresses rapidly into the ov er-lap/channel regions with stress time in a two-stage mechanism, invo lving first a series resistance increase and saturation, followed by a carrier mobility reduction.