The low temperature processing for removal of metallic bismuth in ferroelectric SrBi2Ta2O9 thin films

Abstract

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 SET films had a bad influence on the ferroelectric properties and was easily evaporated by the second annealing in low oxygen pressure (5 Torr) at 650 degrees C. The 120 nm thick Sr0.7Bi2.7Ta2.0O9 films prepared by the second annealing for 0.5 h at 650 degrees C showed a well-saturated hysteresis loop and had a remanent polarization (Pr) of 12 mu C/cm(2), a coercive field (Ec) of 45 kV/cm at an applied voltage of 5 V. The leakage current density of the second annealed SET films was about 4.0 X 10(-8) h/cm(2) at 100 kV/cm. The films showed fatigue-free characteristics up to 2.0 X 10(10) switching cycles under 5 V bipolar pulse. A low temperature processing for removal of metallic Bi in SET films is very attractive for nonvolatile memory applications (C) 1999 Elsevier Science B.V. All rights reserved.