Analytical Model for Interface Traps-Dependent Back Bias Capability and Variability in Ultrathin Body and Box FDSOI MOSFETs

Independent back bias in the ultrathin body and Box (UTBB) fully depleted silicon-on-insulator (FDSOI) serves as the critical knob for exploiting the performance and power tradeoffs and process/aging compensation. The effectiveness of back bias is one of the major metrics in the stages of circuit design and runtime feedback. In this article, new closed-form expressions accounting for the interface traps and short channel effects-dependent back gate capability in the UTBB FDSOI device are proposed. The developed model allows the accurate assessment of body factor ( $\gamma $ ) with the dependence of front/back interface trap density in the ultrascaled FDSOI device, taking the impact of gate area scaling as well as quantum effects into account. It also facilitates the evaluation of back bias effectiveness variability induced by interface traps and benefits the dynamic threshold voltage strategy in terms of adaptive back-biasing for performance optimization, which is consistent with 3-D device simulations and measurements. Moreover, the results confirm that $\gamma $ variability follows Pelgrom’s rule.