A unified understanding on fully-depleted SOI NMOSFET hot-carrier degradation

A unified understanding on fully-depleted SOI (FDSOI) N-Channel MOSFET hot-carrier degradation is presented using a novel methodology and devices fabricated on SIMOX and BESOI substrates. We measured traditionally reported front gate threshold voltage shift and de-coupled front and back gate threshold voltage shifts by accumulating the opposite interface. Interpretation of the experimental results are provided on floating body, bipolar breakdown and series parasitic source/drain resistance (Bds) debiasing effects on hot-carrier degradation. BESOI substrates showed less degradation than SIMOX. However, the degradation mechanisms are same in both substrates. At low drain bias, device degradation is dominated by the coupling of back interface degradation to the front interface. Back interface is degraded by the hole trapping and interface states generation simultaneously. Front interface is degraded by the interface states generation. At moderate drain bias, floating body induced shift in threshold voltage is dominant despite moderate front interface states generation. At high Vds, interface states generation at the back interface and the competing hole trapping and interface states generation at the front interface are observed. Finally, we proposed a phenomenological model for FDSOI N-Channel MOSFET degradation taking into account all dominant effects.