Fundamental limit of gate oxide thickness scaling in advanced MOSFETs

The statistical distribution of the direct tunnel leakage current through the ultrathin gate oxides of MOSFETs induces significant fluctuations in the threshold voltage and the transconductance when the gate oxide tunnel resistance becomes comparable to the gate poly-Si resistance. By calculating the measured tunnel current based on multiple scattering theory, it is shown that the threshold voltage and the transconductance fluctuations will be problematic when the gate oxide thickness is scaled down to about 0.8 nm.