Low-temperature crystallization induced by excimer laser irradiation of SrBi₂Ta₂O₉ films

Transition of a SrBi₂Ta₂O₉ precursor film from amorphous to crystalline was induced by excimer laser irradiation. Both fluorite and perovskite crystalline structures in such films were obtained by excimer laser irradiation at substrate temperatures between 200 and 500 °C. Either an addition of excess bismuth in the precursor film or an increase in the substrate temperature enhanced the formation of the perovskite structure in the excimer laser-induced annealing process, resulting in the perovskite crystalline phase at a relatively lower temperature of 500 °C. Such a low temperature is preferred when SrBi₂Ta₂O₉ is used in ferroelectric devices. The mechanism involved in this laser-induced crystallization is also discussed.