A Compact Interface-Trapped-Charge-Induced Subthreshold Current Model for Surrounding-Gate MOSFETs

With the effects of equivalent oxide charges on the flatband voltage, we report a compact interface-trapped-charge-induced subthreshold current model for the surrounding-gate (SRG) MOSFETs based on the scaling equation and the drift-diffusion approach. It is found that a thin gate oxide can effectively reduce the subthreshold current degradation caused by the positive/negative trapped charges. In contrast to the thin gate oxide, a thick silicon film is required to alleviate the subthreshold current degradation caused by the negative trapped charges. In comparison with the fresh device, the damaged device with negative/positive trapped charges can decrease/increase more subthreshold current roll-up caused by the short-channel effects (SCEs). The model can be used to explore the hot-carrier-induced subthreshold current degradation for the SRG MOSFETs for its memory cell application.