Low temperature processed 0.7SrBi2Ta2O9-0.3Bi3TaTiO9 thin films fabricated on multilayer electrode-barrier structure for high-density ferroelectric memories

Thin films of solid-solution material 0.7SrBi(2)Ta(2)O(9)-0.3Bi(3)TaTiO(9) (0.7SBT-0.3BTT) were fabricated on n(+)-polycrystalline (n(+)-poly) Si substrates by a metalorganic solution deposition technique at a low processing temperature of 650 degrees C using a Pt-Rh/Pt-Rh-O-x electrode-barrier structure. The Pt-Rh/Pt-Rh-O-x structure was deposited using an in situ reactive radio frequency sputtering process. The electrodes had a smooth and fine-grained microstructure and were excellent diffusion barriers between the 0.7SBT-0.3BTT thin film and Si substrate. The ferroelectric (0.7SBT-0.3BTT) test capacitors using these electrode-barrier grown directly on Si showed good ferroelectric hysteresis properties, measured through n(+)-poly Si substrate, with 2P(r) and E-c values of 11.5 mu C/cm(2) and 80 kV/cm, respectively, at an applied electric field of 200 kV/cm. The films exhibited good fatigue characteristics (< 10% decay) under bipolar stressing up to 10(11) switching cycles and the leakage current density was lower 10(-7) A/cm(2) at an applied electric field of 200 kV/cm. The good ferroelectric properties of 0.7SBT-0.3BTT solid-solution thin films at a low processing temperature of 650 degrees C and excellent electrode-diffusion barrier properties of a Pt-Rh/Pt-Rh-O-x structure are encouraging for the realization of high-density nonvolatile ferroelectric random access memories on silicon substrates. (C) 1999 American Institute of Physics. [S0003-6951(99)01240-1].