The transient signal response of submicron vertical silicon field-effect transistors

Abstract

A Monte Carlo simulation has been used to model steady state and transient electron transport in a vertical geometry n-type silicon metal-oxide field effect transistor (Si n-MOSFET). Detailed time-dependent voltage signal analysis has been carried out to demonstrate the modulation response of the device, which has been compared with the result of an identical analysis performed on a more conventional planar geometry silicon-on-insulator n-MOSFET of similar dimensions and doping. The effective source-drain separation of the modelled devices is 90 nm, while the polysilicon gate length and channel width are 50 nm. The calculations suggest that provided the contact resistance and capacitance associated with the drain of similar experimental structures can be limited, the upper limit to the current gain cut-off frequency of this vertical MOSFET is 160±10 GHz, a 50% improvement over the planar device.