New Understanding of Random Telegraph Noise Amplitude in Tunnel FETs

As one of the important sources of lowfrequency noise, random telegraph noise (RTN) in tunnel FET (TFET) has attracted growing attention recently. However, there is still lack of explanation for the high-amplitude RTN, which may cause serious variability and reliability problems to TFET-based ultralow-power circuits. In this paper, we experimentally investigate the RTN amplitude characteristics in TFETs, revealing the mechanism of highamplitude RTN. It is found that the nonuniform distribution of band-to-band tunneling (BTBT) generation rate along device width direction is responsible for the high-amplitude RTN. Locations with relatively higher BTBT generation rate may act as critical paths dominating the device current. “Lucky” trap located at a critical path can induce the high-amplitude RTN. With device width shrinking, the number of critical paths may be reduced, resulting in much higher maximum RTN amplitude. In addition, the impacts of process parameters on RTN amplitude are discussed. Both higher source doping concentration (N
_S
) and higher thermal budget can effectively mitigate the nonuniformity of BTBT generation rate along device width direction, causing suppressed RTN amplitudes. Considering that the higher thermal budget may lead to degraded device performance, the annealing process should compromisingly be designed in terms of both variation and device performance.