The physical phenomena responsible for excess noise in short-channel MOS devices

The physical phenomena responsible for the excess noise in short-channel MOS devices are explained based on the non-equilibrium noise theory. Comparing the MOS excess noise with the well known excess noise in a mesoscopic conductor, it is suggested that the physical origins of both are the same. Using this theory, it is proposed that the noise sources used in the impedance field method (IFM) should contain not only the usual thermal noise component, but also a partially suppressed shot noise term which accounts for the limited number of inelastic scattering events in the channel. The theoretical predictions of a simplified model based on this theory are presented and compared with the measurement results. It is shown both theoretically and experimentally that the non-equilibrium noise component is smaller when a larger gate to source voltage is applied. The accurate calculation of the suppression factor, which is in general a function of device terminal voltages, remains a challenge.