Cutoff frequency and propagation delay time of 1.5-nm gate oxide CMOS

The high-frequency AC characteristics of 1.5-nm direct-tunneling gate SiO₂ CMOS are described. Very high cutoff frequencies of 170 GHz and 235 GHz were obtained for 0.08-μm and 0.06-μm gate length nMOSFETs at room temperature. Cutoff frequency of 65 GHz was obtained for 0.15-μm gate length pMOSFETs using 1.5-nm gate SiO₂ for the first time. The normal oscillations of the 1.5-nm gate SiO₂ CMOS ring oscillators were also confirmed. In addition, this paper investigates the cutoff frequency and propagation delay time in recent small-geometry CMOS and discusses the effect of gate oxide thinning. The importance of reducing the gate oxide thickness in the direct-tunneling regime is discussed for sub-0.1-μm gate length CMOS in terms of high-frequency, high-speed operation