On the Understanding of Aging-Induced Band Tail States Under Cryogenic Temperatures

Le résumé fourni par la source

This work investigates how bias-temperature-instability (BTI) stress affect the transfer characteristics of FinFETs under cryogenic temperatures. Compared with room-temperature operation, BTI-stressed devices exhibit counterintuitive trends: a reduced subthreshold swing (SS), an increased on-current (Ion), and a higher peak transconductance (Gmmax). We attribute these shifts to the charge trapping of near-interfacial defects of which the thermal emission is strongly suppressed at cryogenic temperature. The resulting persistent occupancy perturbs band-edge states at the interface and reshapes the band tail states distribution—enhancing the localized states while reducing the transport states. The physical simulations quantitatively reproduce these behaviors, supporting the proposed mechanism. In addition, ab-initio calculations implicate oxygen vacancies (Vo) within interfacial layers in PMOS as the dominant traps. These results explain the reasons for the aging phenomenon of cryo-devices and identify an additional origin of band tail states relevant to cryogenic operation.

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