The Praparation Of BaTiO₃ Thin Film By Spin Spray Pyrolysis And The Research Of Dielectric Property

With the development of the technology, BaTiO3 thin film, as a special material, has already been a base for microelectronics, communication, sensor, optics and penetrated into many parts of the science field. There are many physical methods to prepare BaTiO3 thin film, such as radio-frequency magnetron sputtering, pulsed laser deposition, MBE and many chemical methods such as Sol-Gel, metalorganic chemical vapor deposition(MOCVD), hydrothermal and so on.. Generally, the physical methods need vacuum environment, which are so strict to the apparatus that current laboratory can hardly achieve it. Compared with physical technologies, the chemical technologies are much easier and do not need complicated equipments.In this paper, we designed and assembled the device of spin spray pyrolysis, which was upgraded and improved through experiments, and finally finalized the design. BaTiO3 thin films were explored by the device of spin spray pyrolysis made at home. BaTiO3 precursor solution was made using tetrabutyl titanate and barium acetate as raw materials. Quartz and Si wafers were used as substrates. The effects of preparation conditions such as anneal temperature, heating rate, annealing time and rotational speed on the structure, surface morphology and electrical properties of the film were investigated with TG (thermogravimetry), XRD (crystal structure), SEM, step profiler (film thickness) and capacitance. The feasibility and performance of equipment were also tested by the preparation of barium titanate thin films.The results show that the spin spray pyrolysis device can prepare BaTiO3 thin film successfully. Anneal temperature, heating rate, annealing time and rotational speed have certain effects on the structures and surface morphologies of BaTiO3 thin films. The best conditions for preparing BaTiO3 thin films were as follows:the substrate temperature, nozzle distance, gas flow, anneal temperaturew, heating rate, annealing time and rotational speed were 150℃,20 mm, 1L/min,700℃,5/min,60min and 4000r/min, respectively. The dielectric constant of the thin film annealed with 700℃is 198 measured at 1KHz and 293K. The change rate of dielectric constant with temperature is relatively small.Barium titanate thin films were prepared with magnetron sputtering method in this paper, the dielectric constant of which was also measured. Comparing with the barium titanate thin film prepared by spin spray pyrolysis, the dielectric constant of the former was much lower.