Direct lateral profiling of hot-carrier-induced oxide charge and interface traps in thin gate MOSFET's

A simple charge pumping method has been developed to measure the localized hot-carrier damage in scaled thin-gate MOSFET's. Lateral distributions of both interface traps and oxide charge can be derived directly from experimental charge pumping results without numerical simulation. By the use of this method, we have studied the erase-induced hot-carrier damage in flash EPROM devices, including the lateral distributions of both oxide charge (trapped holes) and interface traps. We discovered the following: the damage is confined within the source diffusion region with a rather wide distribution; the erase-induced oxide charge density is orders of magnitude more than erase-induced interface traps; both the peak density and width of the damage depend strongly on the junction bias during the erase operation. These results should be very useful for the reliability modeling and future device design of flash EPROM's.