Two-dimensional simulation of band-to-band tunneling in an LDD-MOSFET: explanation of experimental results and prediction of new phenomena

A generalization of band-to-band tunneling (BTBT) in two dimensions was implemented using a MINIMOS device simulator. The BTBT-related leakage currents of a MOSFET were simulated as functions of drain/gate bias, oxide thickness, and lightly-doped drain (LDD) structure and found to be in agreement with experiment. It is found that in the deep subthreshold regime at high drain voltage, the leakage currents result from the combined effects of BTBT and impact ionization. The model allows a quantitative explanation of the recently reported enhanced transistor degradation due to BTBT. In addition, a new mode of BTBT-related leakage for deep-submicron MOSFETs in the entire channel region is predicted