Ferroelectric strontium bismuth tantalate thin films deposited by metalorganic chemical vapour deposition (MOCVD)

摘要

Thin films of Sr_(1-x)Bi_(2+x)Ta_2O_9 (SBT) have been deposited by metalorganic chemical vapor deposition (MOCVD) on 150 mm Si wafers with Pt/Ti electrodes. The choice of Bi precursor significantly affects the process; film homogeneity is significantly improved when using alpha beta -diketonate Bi precursor in combination with compatible Sr and Ta precursors. A highly repeatable proces has been developed, with good run-to-run composition and thickness control. Effects of Bi volatility have been investigated in annealing experiments that show the onset of Bi loss at approx 570 deg C at reduced pressure (1-10 Torr). Film properties relevant to integrated ferroelectric random access (Fe RAMS) memories have also been characterized. Remenant polarizations (2P_r) up to 24 mu C cm~(-2) have been obtained at 5 V, with 90