Impurities in dielectrics and hydrogen barriers for SrBi2Ta2O9-based ferroelectric memories

We report results of systematic investigation of impurities in dielectrics and hydrogen barriers (Ti and Al2O3 films) during the integration process of SrBi2Ta2O9-based ferroelectric memories. The capacitors integrated with Ti hydrogen barriers are not electrically degraded regardless of the annealing conditions of the subdielectrics. On the contrary, electrical properties of the capacitors using Al2O3 hydrogen barriers significantly depend on the annealing temperatures for subdielectrics. It turned out that interaction of the dielectrics with plasma during sputtering of the Ti films caused fragmentation of the moisture in the dielectrics and absorption of the hydrogen in the Ti films, making annealing irrelevant. However, the alumina films blocked both hydrogen and moisture in the subdielectrics during the passivation process, resulting in dependence on the annealing temperatures. (C) 2001 American Institute of Physics.