Investigation of Positive and Negative Bias Temperature Instability of High-\kappa Dielectric Metal Gate Metal--Oxide--Semiconductor-Field-Effect-Transistors by Random Telegraph Signal

We investigate the impact of positive and negative bias temperature instability (P/NBTI) on the current degradation by using the drain current random telegraph signal (Id-RTS) in high-kappa gate dielectric and metal-gate MOSFETs. The samples were stressed at typical BTI oxide electric field (similar to 7 MV/cm) and Id-RTS amplitude (Delta Id-RTS) distributions were measured before and after P/NBTI stress. It is shown that Id-RTS degradation (Delta Id-RTS /Id-RTS) in NBTI devices exhibits a wider amplitude distribution than the PBTI one. In addition, we trace trapped charge-induced saturation current I-D,I-sat degradation in P/NBTI stress. As a result, the statistical analysis indicates that Delta/I-D,I-sat/I-D,I-sat of the p-MOSFET is larger than Delta I-D,I-sat/I-D,I-sat of the n-MOSFET. Moreover, the lifetime of the device is numerically estimated based on current degradation with or without RTS. We consequently found that P/NBTI lifetime comes worse by considering the effect of RTS. (c) 2013 The Japan Society of Applied Physics