EFFECTS OF MICROSCOPIC FLUCTUATIONS IN DOPANT DISTRIBUTIONS ON MOSFET THRESHOLD VOLTAGE

The effects of fluctuations in dopant distribution on the MOSFET threshold voltage and their dependence on the scaling were investigated, using device simulation. The simulation indicates that the microscopic fluctuations in dopant distribution not only induces threshold-voltage deviations, but also lowers the mean threshold-voltage value. It was also found that the threshold-voltage deviation is mostly affected by fluctuating dopant distribution at the substrate surface, rather than throughout the depletion layer. Discussion incorporating microscopic fluctuations in surface electric potential, due to fluctuating dopant distribution, explained not only deviations but also the mean value lowering of the threshold voltage in the simulation.