Accuracy and Issues of the Spectroscopic Analysis of RTN Traps in Nanoscale MOSFETs

This paper investigates the limitations to the accuracy and the main issues of the spectroscopic analyses of random telegraph noise (RTN) traps in nanoscale MOSFETs. First, the impact of the major variability sources affecting decananometer MOSFET performance on both the RTN time constants and the trap depth estimation is studied as a function of the gate overdrive. Results reveal that atomistic doping and metal gate granularity broaden the statistical distribution of the RTN time constants far more than what comes from the random position of the RTN trap in the 3-D device electrostatics, contributing, in turn, to a significant reduction of the accuracy of trap spectroscopy. The accuracy is shown to improve the higher is the gate overdrive, owing to a more uniform and gate-bias-independent surface potential in the channel, with, however, the possible drawback of triggering the simultaneous trap interaction with both the channel and the gate. This simultaneous interaction is, finally, shown to critically compromise trap spectroscopy in thin-oxide devices.