ULTRA-FAST (0.5-MU-M) CMOS CIRCUITS IN FULLY DEPLETED SOI FILMS

CMOS dual-modulus, divide by 128/129, prescaler circuits were built in thin Si films on SIMOX (Separation by IMplantation of OXygen) wafers. They operated at 6.2 GHz, the highest speed ever reported for a digital CMOS circuit, and 50% faster than the control circuits built in bulk Si. We made detailed electrical characterization of individual n- and p-channel transistors. The capacitances of the n and p diodes were also measured. Using these data in circuit simulations we determined that the gain in speed was primarily due to the decrease in the parasitic capacitances, in particular that of the source/drain junctions. We also measured ring-oscillator delay times, with minimum delay per stage of 34 ps.