Suppression of Stand-by Tunnel Current in Ultra-Thin Gate Oxide MOSFETs by Dual Oxide Thickness-Multiple Threshold Voltage CMOS (DOT-MTCMOS)

Abstract

A new circuit scheme, dual oxide thickness–multiple threshold voltage complementary metal oxide semiconductor (CMOS) (DOT-MTCMOS) which can suppress the stand-by tunnel leakage in ultra-thin gate oxide metal semiconductor field effect transistors (MOSFETs) is proposed. In this circuit, a power switch is inserted in series with CMOS circuits. The power switch consists of a high Vth MOSFET with relatively thick gate oxide, in order to suppress not only subthreshold leakage but also tunneling leakage in the stand-by mode, while the CMOS circuit consists of low Vth MOSFETs with ultra-thin gate oxide for the high speed and low voltage operation. Using this circuit scheme, we can utilize the high drive current of ultra-thin gate oxide MOSFETs in the future where the scaling limit of the gate oxide thickness will not be determined by the stand-by power. An application of this scheme to a low voltage operation, hence low power circuit, is also demonstrated.