THE ROLE OF RAPID THERMAL-PROCESSING IN CRYSTALLIZATION OF SBT THIN-FILMS

Investigation of the annealing conditions of SrBi2Ta2O9 (SBT) films sh owed that crystallization behavior and grain growth is significantly a ffected by temperature ramp rates. Thin films of SET were deposited on Si/SiO2/Ti/Pt substrates using MOD (Metal-Organic Decomposition) two layer spin-on processing. The films were annealed at 800 degrees C in diffusion furnace under flowing O-2 for complete crystallization. It w as found that the grain growth could be enhanced, leading to improved ferroelectric properties, by introducing a two step anneal methodology . The first step involves rapid thermal annealing (RTA) of the SET lay ers at temperatures close to 700 degrees C for 30 sec. at ramp rates b etween 75 to 125 degrees C/sec. followed by the second anneal employin g a diffusion furnace at 800 degrees C for 30 to 60 min. This first RT A step is considered to be very important as it promotes grain growth when followed by diffusion anneal at 800 degrees C. A similar diffusio n anneal, in the absence of RTA, wasn't enough to yield a dense film.