Evidence of Tunneling Driven Random Telegraph Noise in Cryo-CMOS

CMOS technologies operating at cryogenic temperatures play a key role in the successful deployment of quantum computers. While tremendous efforts have been devoted to understanding the de-vice electrostatics, there is a lack of studies on the device performance degradation mechanisms, as for instance bias temperature instability (BTI), in cryogenic environments. To study BTI, typically large-area devices are characterized. However, as we demonstrate, when approaching the cyrogenic temperature regime, the investigation of single defects becomes necessary. Using single defect measurements, we show that even at 4 K, there are active defects causing random tele-graph noise (RTN). We can explain the temperature dependence of the charge transfer mechanism by nuclear tunneling in the framework of the nonradiative multi-phonon (NMP) model. Our measurements and simulations indicate that interface defects are responsible for RTN at cryogenic temperatures. Due to their small relaxation ener-gies and displacements during charge transitions, interface traps have high charge transition rates and do not freeze out, thus playing a cru-cial role for a high-performance operation of noise-sensitive circuits in cryogenic environments.