Real-time analysis of ultra-thin gate dielectric breakdown and recovery - A reality

Switching behaviours have been observed after gate dielectric breakdown under certain favourable conditions. In our recent report in IEDM 2009, the conductive breakdown path in gate dielectric can be 'switched-off' if a reverse bias, as opposed to the stressing voltage, is applied, a condition required for observing SET and RESET conduction in bipolar switching material systems. Similar phenomenon has also been observed for unipolar switching. This means that breakdown transistor can be 'repaired' electrically by a reverse threshold voltage to expand its lifetime. More recently, detailed insights of the dielectric breakdown and recovery were reported by real-time transmission electron microscopy analysis. In this invited talk, the real-time TEM analysis of the physical structure and morphology of breakdown paths in high-k/metal gate system while under electrical stress is discussed. The results are further correlated with the chemical composition of the breakdown path dynamically during breakdown and recovery. Oxygen vacancies and metal atoms from the anode constitute the chemistry of the nanoscale breakdown path.