THE EFFECT OF POST-ANNEALING ON BARIUM STRONTIUM TITANATE FILMS DEPOSITED BY RADIO FREQUENCY MAGNETRON SPUTTERING

摘要

Barium strontium titanate (BST) films were deposited on thermally oxidized Si wafers using radio frequency (RF) magnetron sputtering at substrate temperature of 673K. The effects of electric furnace annealing and rapid thermal annealing on the structures, the composition distributions and the morphologies of the films have been investigated. The structures and the compositions are analyzed using grazing X-ray diffraction (GXRD) and X-ray photoelectron spectroscopy (XPS), respectively. The morphologies are observed by atomic force microscopy (AFM). XPS shows that the films exhibit uniform composition distributions. GXRD indicates that a critical annealing temperature of approximately 723K corresponds to the appearance of crystallization. An increasing annealing temperature corresponds to an enhancing crystallization. An optimum annealing temperature of 873K corresponds to an appropriate crystallization, causing smooth and dense structure. Meanwhile, the electric furnace annealed films show (110) preferred orientation. However, at the same annealing temperature rapid thermal annealing in Ar/O_2 (1:1) ambient corresponds to better-crystallized films with smoother and denser structure than electric furnace annealing. The crystal grain shows an average size of 20-30nm and grows along (111) orientation preferentially.