Reduction of Process-induced Damage and Improvement of Imprint Characteristics in SrBi2Ta2O9 Capacitors by Postmetallization Annealing

We investigated the effect of process damage induced after capacitor etching procedures in the process of ferroelectric random access memory (FeRAM) fabrication for SrBi2Ta2O9 capacitors. We found that this damage was suppressed by postmetallization annealing (400 °C, 30 min in O2) and that imprint characteristics were improved by the annealing, because active elements such as hydrogen and water induced during contact hole formation on tungsten plugs and first-metal formation are adsorbed effectively by the annealing before they penetrate into these capacitors.