Gate Tunneling Current Fluctuations associated with Random Dopant Effects

Random-dopant-induced gate tunneling current fluctuations are studied for the first time. It is shown that gate leakage currents considerably fluctuate among MOSFETs even if there is no gate oxide thickness fluctuation. The physical origin of random-dopant-induced gate tunneling current fluctuations near the stand-by (Vg≈ +0 V) is the fluctuations in source-to-channel p-n junction location rather than the fluctuations in normal oxide field. Statistical variations of p-n junction location due to random impurities are essential for ultra-small MOSFETs and should be appropriately taken into account in the device simulation.