Effects of Annealing in H_2-Containing Ambient on Surface Morphologies and Ferroelectricities of SrBi_2Ta_2O_9 Ferroelectric Thin Films

The forming gas (FG,95% N 2+5%H 2) annealing step required in microchip fabrication results in an unacceptable degradation of the electric properties of SrBi 2Ta 2O 9 (SBT) thin films. It is an important question in SBT thin films applications. The effects of annealing in forming gas on the surface morphologies and ferroelectricities of SBT thin films are studied. SBT ferroelectric thin films are fabricated on the Pt/TiO 2/SiO 2/Si substrates by metal-organic decomposition (MOD) methods. The films are annealed in forming gas. Experimental results show that the degradation of ferroelectric properties of SBT thin films can be attributed to the depletion of Bi element caused by the reductive effect of hydrogen. Results of SEM show that Bi is in the columnar structures on SBT surface. However, the ferroelectric properties of SBT thin films can be recovered by oxygen annealing at 750℃ temperature for 1 h. It is attributed to the oxidation of oxygen.