Effect of reverse biased voltage at source and drain on plasma damage

We have examined the possible effects of reverse-biased floating potential at the source and drain during plasma processing on the performance of n-channel metal-oxide-semiconductor field-effect transistors (MOSFETs). Threshold voltage degradation was evaluated by subjecting the gate oxide to high-field injection. Device degradation is found to be enhanced with the floating potential at source and drain for the devices subjected to substrate injection. An increase in electron trapping was observed with an increase in floating potential. Estimation shows that the effective antenna ratio of MOSFET increases with the reverse-biased floating voltage at source and drain. Our results indicate that plasma-charging damage can be significant even under uniform plasma if a potential is developed at the antenna-connected source and drain terminals. Damage in devices subjected to gate injection on the other hand, could have minimal dependence on source and drain potential.