Defect-Centric Distribution of Channel Hot Carrier Degradation in Nano-MOSFETs

Abstract

The defect-centric distribution is used, for the first time, to study the channel hot carrier (CHC) degradation. This distribution has been recently proposed for bias temperature instability (BTI) shift and we show that it also successfully describes the CHC behavior. This distribution has the advantage of being described by two physics-based parameters, the average threshold voltage shift produced by a single charge η and the number of stress-induced charged traps N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</sub> . We study the behavior of η and N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</sub> on nFETs with different geometries for different CHC stress times. As in the case of BTI, we observe that: 1) during the CHC stress, η is constant and N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</sub> increases at the same rate of ΔV <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> and 2) η scales as 1/Area. We show that the density of charged traps induced by CHC stress strongly increases with reducing channel length, in contrast to BTI, where the density of charged traps is independent of the device geometry. The defect analysis enabled by the defect-centric statistics can be used to deepen our understanding of CHC degradation in nanoscale MOSFETs, where the defects are reduced to a numerable level.