Numerical and experimental study of a 0.25 µm fully-depleted silicon-on-insulator MOSFET: static and dynamic radio-frequency behaviour

Abstract

We investigate the static and dynamic characteristics of a 0.25 µm gate-length fully-depleted silicon-on-insulator metal–oxide–semiconductor field effect transistor. Considering properly the physical topology of the transistor with its accesses, numerical simulations are performed using a two-dimensional ensemble Monte Carlo simulator and these are compared with experimental results. Moreover, in the simulation we include important effects that appear in real transistors, such as surface charges, contact resistances, impact ionization phenomena and extrinsic parasitic capacitances. The appearance of a velocity overshoot region near the drain, together with the presence of hot carriers in the channel, is observed in the saturation regime. The dynamic behaviour of the device is described through significant small signal equivalent circuit parameters, which are examined by means of internal quantities (such as profiles of the internal electron concentration), provided by numerical simulations. In general, the device shows excellent performance in terms of important design parameters, such as transconductance-to-current ratio, transconductance and cut-off frequency together with a reduced capacitive coupling to the substrate. The results of the Monte Carlo simulations show an exceptional agreement with the experimental data, thus confirming the validity of the simulator as a reliable tool for the analysis of the influence of geometrical and electrical parameters on the static and dynamic performance of the device.