Asymmetric Halo CMOSFET to Reduce Static Power Dissipation With Improved Performance

Abstract

In this paper, we show the benefits of using asymmetric halo (AH, different source, and drainside halo doping concentrations) MOSFETs over conventional symmetric halo (SH) MOSFETs to reduce static leakage in sub-50-nm CMOS circuits. Device doping profiles have been optimized to achieve minimum leakage at iso on-current. Results show a 61% reduction in static leakage in AH nMOS transistor and a 90% reduction in static leakage in AH pMOS transistor because of reduced band-to-band tunneling current in the reverse biased drain-substrate junctions. In an AH CMOS inverter, static power dissipation is 19% less than in an SH CMOS inverter. Propagation delay in a three-stage ring oscillator reduces by 11% because of reduced drainside halo doping and hence reduced drain junction capacitance. Further comparisons have been made on two-input NAND and NOR CMOS logic gates.