Low voltage substrate current: a monitor for interface states generation in ultra-thin oxide n-OSFETs under constant voltage stresses

The low voltage substrate current (I_b) has been studied based on generation kinetics and used as a monitor of interface states (N_it) generation for ultra-thin oxide n-MOSFETs under constant voltage stress. It is found that the low voltage I_b is formed by electrons tunnelling through interface states, and the variations of I_b(\DeltaI_b) are proportional to variations of N_it (\DeltaN_it). The N_it energy distributions were determined by differentiating N_it(V_g). The results have been compared with that measured by using gate diode technique.