A Comparative Study of NBTI and RTN Amplitude Distributions in High- Gate Dielectric pMOSFETs

摘要

Random telegraph noise (RTN) and negative bias temperature (NBT) stress-induced threshold voltage $(V_{t})$ fluctuations in high- $kappa$ gate dielectric and metal-gate pMOSFETs are investigated. We measured RTN amplitude distributions before and after NBT stress. RTN in poststressed devices exhibits a broader amplitude distribution than the prestress one. In addition, we trace a single trapped charge-induced $ Delta V_{t}$ in NBT stress and find that the average $Delta V_{t}$ is significantly larger than a $Delta V_{t}$ caused by RTN. A 3-D atomistic simulation is performed to compare a single-charge-induced $Delta V_{t}$ by RTN and NBTI. In our simulation, the probability distribution of a NBT trapped charge in the channel is calculated from the reaction-diffusion model. Our simulation confirms that the NBT-induced $Delta V_{t}$ indeed has a larger distribution tail than RTN due to a current-path percolation effect.