Transient relaxation, which has been addressed as an undesirable issue in high-k alternate gate dielectrics, has been studied systematically. In Hf-based dielectrics, it follows a universal line irrespective of stress times and stress voltages if stressed
(static/dynamic) up to certain limits. The results presented here reveal that bulk charge trapping shows a fast transient relaxation (TR) for a very short time (. ms) after stress (substrate injection) followed by a slow relaxation (> 1 s), while interface passivation/
relaxation follows a slow trend. Bulk trappings, which play a major role in causing device instabilities in high-k gate oxides, are mostly relaxable, while interface degradation cannot be passivated completely. Moreover, an interface-passivation mechanism seems to be independent of stress histories. Devices with stronger bulktrapping immunity showed faster TR. The experimental results show good agreement with the simplified mathematical model presented for HfO2 gate oxides. The temp