Abstract:
(Vp) well below the bandgap voltage of silicon has received
widespread attention [1,2,3]. Substrate currents (Isue) for
drain voltages down to 0.6V [1] and floating body effects in
SOI devices down to 0.8V [2] were reported. This would
imply that the impact ionization induced operational and
reliability issues in nMOSFETs will continue to deca-nano
meter device generations.
Based on Monte Carlo simulations it was suggested that
various modes of elecffon-electron interactions resulting in
the high energy tail (HET) of the electron energy distribution
are responsible for some elecfrons to have more energy than
that gained from the lateral electric field (E61) [3,4]. An
anomalous increase of the gate voltage at which the Isus
peaks (Vcp"ud which can not be explained by HET is
presented. We have also compared the sub-bandgap impact
ionization in CONventional (CON) and Lateral
Asymmetrical Channel (LAC) nMOSFETs of channel length
l00nm. An enhancement of the increase in V60..1 is found in
the LAC devices. Based on the results presented we propose
quantization of inversion layer as an additional energy gain
mechanism for the electrons.