The low temperature processing for removal of metallic bismuth in ferroelectric SrBi Ta O thin films

A low temperature processing of a modified rf magnetron sputtering has successfully applied to obtain a ferroelectric SrBi2Ta2O9 SBT.thin films. The excess metallic bismuth in SBT films had a bad influence on the ferroelectric properties and was easily evaporated by the second annealing in low oxygen pressure 5 Torr.at 6508C. The 120 nm thick Sr0.7Bi2.7Ta2.0O9 films prepared by the second annealing for 0.5 h at 6508C showed a well-saturated hysteresis loop and had a remanent polarization Pr. of 12 mCrcm2, a coercive field Ec.of 45 kVrcm at an applied voltage of 5 V. The leakage current density of the second annealed SBT films was about 4.0=10y8 Arcm2 at 100 kVrcm. The films showed fatigue-free characteristics up to 2.0=1010 switching cycles under 5 V bipolar pulse. A low temperature processing for removal of metallic Bi in SBT films is very attractive for nonvolatile memory applications q1999 Elsevier Science B.V. All rights reserved.