Preparation Of STO Films By RF Magnetron Sputtering

Strontium titivate thin film (STO) is a dielectric material for the applications in electronic devices such as dynamic storage, large scale integrated circuit because of it’s the high dielectric constant, small leakage current, low loss and good thermal stability. The thin film’s properties will directly affect the performance of the corresponding products. The device miniaturization, integration and multifunction have already become major tendencies with the rapid development of the microelectronic integration, sensors and optoelectronic technology. This research focused on improving the preparation of thin film technology and enhancing the performance of the thin films.The STO thin films were deposited on Pt/Si substrates by RF-magnetron sputtering, and the deposition conditions of thin films were investigated particularly. The components, thickness, surface morphology, phase structure and microstructure of the thin films were analyzed by the experimental test. The double SrTiO3thin films were deposited on Pt/Si substrates by changing the preparation process, and their performances were studied. The following results are obtained:(1) The STO thin films present preferred orientation growth which were deposited on Pt/Si (111) and Pt/Si (220) substrate. The STO thin films orientatively grew because the substrate orientation can significantly induce the growth of the films. We can deposit the thin films with different preferred orientations by using different substrates.(2) The STO thin film with different thicknesses were deposited on Pt/Si substrate by changing the sputtering time, and fitted the function between the sputtering time and the films thickness. Therefore, the thickness of the thin films was controlled by changing the sputtering time.(3) The optimum conditions of RF-magnetron sputtering have been obtained through a large number of experiments:the substrate temperature is500℃, sputtering pressure is0.18Pa, sputtering gas ratio between O2and Ar is2, the sputtering time is90min, annealing temperature is700℃under aerobic environment.(4) The STO double thin films were deposited on Pt/Si (111) substrate by RF-magnetron sputtering, then the process was repeated, the deposition condition is substrate temperature of500℃and annealing temperature of700℃under aerobic environment. The sputtering atoms have sufficient kinetic energy to diffuse, nucleate and grow, and the two times annealing makes the film crystallization completely. The double STO thin films are better than the single thin films at stoichiometric ratio, grain size, film smoothness, compactness and crystallization, which show that this preparation process improve the performances greatly.