Properties of ultra-thin wafer-bonded silicon-on-insulator MOSFET's

Abstract

Strong interface coupling effects on the subthreshold and transconductance characteristics have been experimentally observed and analytically modeled. For total depletion, the subthreshold swing reaches a nearly ideal value. The front channel subthreshold slope of ultrathin MOSFETs is very sensitive to the density of states at the buried Si-SiO/sub 2/ interface so that a thicker fully depleted film is preferable when the quality of this interface is poor. The transconductance reaches a maximum for total depletion. Simple theoretical models are proposed which explain the substantial variations of the transconductance and subthreshold slope as the opposite interface is scanned from inversion to total depletion and accumulation. These MOSFETs behave very well and demonstrate that high carrier mobilities and low densities of defects can be obtained at both interfaces even in ultrathin silicon-on-insulator (SOI) structures.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>