Low-temperature substrate current characterization of N-channel MOSFET's

The substrate-to-drain current ratio is investigated over the temperature range of 77-292K for various MOS device geometries and oxide thicknesses. It is experimentally verified that, at any given temperature in the range of interest, a widely used semi-empirical model for substrate current continues to be valid. Inherent to the verification process, the temperature dependence of the saturation voltage is also investigated experimentally. One implication arising from the results is that, as temperature decreases, the driving force of hot-electron phenomena, namely the product of the mean free path of the electron and the maximum channel electric field, increases less than expected.