An energy-level perspective of bias temperature instability

Abstract

Many recent publications discussing the stress and recovery behavior of bias temperature instability (BTI) have suggested the existence of two components contributing to the phenomenon. One of these components was found to be quickly relaxing while the other was only slowly relaxing or even permanent. Curiously, although the most likely suggested mechanisms are the generation of interface states and the capture of holes into pre-existing traps, there is no agreement on which mechanism corresponds to which component and both possibilities have been suggested. Alternatively, other groups have suggested evidence that BTI is dominated by a single mechanism, and used the reaction-diffusion (RD) model to describe the degradation. However, RD theory cannot explain the recovery and related intricacies of the phenomenon. We present a new modeling framework based on the various possible energetic configurations of the system and tentatively assign these levels to the hydrogen binding/transport levels in an amorphous oxide. We investigate the possibility that the often observed recoverable and permanent components are in fact two facets of a single degradation mechanism proceeding as a series of steps. We finally subject the model to various experimental data (DC, AC, duty-factor, negative and positive stress, mixed stresses) which are all well reproduced by the model.