Investigation of hydrogen-induced degradation in Pb(ZrxTi1−x)O3 thin film capacitors for the application of memory devices

Hydrogen-induced degradation in Pb(ZrxTi1−x)O3 (PZT) thin film capacitors is investigated in terms of three process parameters, such as electrode structures (Pt/PZT/Pt and Ir/IrO2/PZT/Pt/IrO2), Zr/Ti compositional ratios (60/40, 53/47, 40/60, 30/70), and the domain poling states (±5 V). It was found that the hydrogen-induced degradation is enhanced when PZT films have high Ti portion, and can be suppressed by domain poling prior to the hydrogen anneal. From secondary ion mass spectroscopy analysis, it can be concluded that the hydrogen-induced degradation originates mainly from the interface of PZT and Pt electrodes. Hysteresis loop shifts in PZT capacitors indicate that negative charge develops at interfaces by the hydrogen anneal. Chemically, hydrogen-induced degradation can be elucidated as the formation of negatively charged hydroxyl group (OH−).