Ferroelectric S $r_{0.9}$/B $i_{2.1}$/T $a_{2}$/ $O_{9}$ solutions were synthesized using sol-gel process in which strontinum ethoxide bismuth ethoxide trantalum ethoxide were used a s startring materials. SBT thin films were coated on Pt/Ti/ $SiO_2$/Si substrates by spin-coating. rapid thermal annealing (RTA) was used to promote crystallization. Thin films were annealed at $700^{circ}C$ for 1 hr in an oxygen atmosphere. This temperature is about 10$0^{circ}C$ lower than the usual annealing temperature for SBT thin films. Pt top-electrode was deposited by sputtering and thin films were post-annealed at $700^{circ}C$ for 30 min. to enhance electrical properties. As the RTA temperature increased the higher 2 $P_{r}$ values were obtained. At RTA temperature being 78$0^{circ}C$ remanent polarization of S $r_{0.9}$/B $i_{2.1}$/T $a_{2}$/ $O_{9}$ thin film was 7.73 $mu$C/cm $_2$ and the leakage current density was 1.14$ imes$10$^{-7}$ A/c $m^2$ at 3 V. As RTA temperature increased the breakdown voltage was decreased. It is considered that the low-field breadown is caused by the rough surface of SBT films and forming bismuth metal in SBT thin films.films.lms.