Characteristics of Gate Current Random Telegraph Signal Noise in SiON/HfO2/TaN p-Type Metal-Oxide-Semiconductor Field-Effect Transistors under Negative Bias Temperature Instability Stress Condition

Gate dielectric traps are becoming a major concern in the high-k/metal gate devices. In this paper, new experimental results and in-depth study on gate current random telegraph signal (I-g RTS) noise in SiON/HfO2/TaN gate stack p-type metal-oxide-semiconductor field-effect transistors (PMOSFETs) are reported. Single carrier trapping/detrapping in the high-k/metal gate stack under negative bias temperature instability (NBTI) stress is observed for the first time. The location of traps, the impacts of gate bias, temperature and substrate bias are discussed for understanding the RTS mechanism in high-k devices. Moreover, during long time stress, an abrupt change of amplitude of Ig fluctuation and the mean capture and emission time is also observed for the first time, due to new trap generated or activated by the NBTI degradation. The characteristics of the single carrier trapping/detrapping behavior under NBTI stress are very different from that on the normal bias condition, which give us more information about the traps in the high-k/metal gate stack. (C) 2010 The Japan Society of Applied Physics