Ensemble Monte Carlo study of channel quantization in a 25-nm n-MOSFET

We develop a self-consistent, ensemble Monte Carlo device simulator that is capable of modeling channel carrier quantization and polysilicon gate depletion in nanometer-scale n-MOSFETs. A key feature is a unique bandstructure expression for quantized electrons. Carrier quantization and polysilicon depletion are examined against experimental capacitance-voltage (C-V) data. Calculated drain current values are also compared with measured current-voltage data for an n-MOSFET with an effective channel length (L_eff) of 90 nm. Finally, the full capabilities of the Monte Carlo simulator are used to investigate the effects of carrier confinement in a L_eff=25 nm n-MOSFET. In particular, the mechanisms affecting the subband populations of quantized electrons in the highly nonuniform channel region are investigated. Simulation results indicate that the occupation levels in the subbands are a strong function of the internal electric field configurations and two-dimensional (2-D) carrier scattering