Preparation of (Ba, Sr)TiO3Thin Films by Chemical Vapor Deposition Using Liquid Sources

Thin films of (Ba, Sr)TiO3with high dielectric constant were prepared on Pt/SiO2/Si substrates of 6-inch-diameter by chemical vapor deposition using liquid sources. Ba(DPM)2and Sr(DPM)2dissolved into tetrahydrofuran were vaporized in a vaporizer at 523 K, and Ti(O-i-C3H7)4was bubbled at 313 K. The mixture of the source vapors with O2and N2O was supplied to the reactor (10 Torr) at uniform velocities through a shower-type nozzle, which realized uniform profiles in the deposited film thickness and composition. The electrical properties are significantly influenced by the film composition, and the typical properties obtained for a 800-Å-thick film prepared at the substrate temperature of 823 K are an equivalent SiO2thickness teqof 5.2 Å, a leakage current JLof 2.4× 10-6A/cm2(at 1.65 V), and a dielectric loss tan ? of 0.07.