Aerosol-Deposited (Ba,Sr)TiO3 Thick Films Prepared by Rapid Thermal Annealing for Microwave Applications

Abstract

Barium strontium titanate (BST; Ba0.5Sr0.5TiO3) thick films were successfully deposited on a Cu substrate by the aerosol deposition (AD) process in the room temperature range. The aerosol-deposited BST thick films were annealed in pure 02 and N-2 atmospheres at 100, 200, and 300 degrees C by the rapid thermal annealing (RTA) process. A sandwich-type vertical capacitive structure was fabricated on the BST thick films to obtain dielectric properties. It was found that the aerosol-deposited BST thick films had a very dense structure and good adhesion. The difference between the effects of 02 and N2 atmospheres on the electrical behavior of the BST thick films was investigated after RTA. Analysis of the X-ray diffraction (XRD) patterns of the films showed that the aerosol-deposited BST thick films had a perovskite structure without any secondary phases. The relative permittivity and loss tangent of the as-deposited BST thick films were 83 and 0.02, respectively, at 1 MHz. In addition, after the RTA process in O-2 and N-2 atmospheres, the relative permittivities of the BST thick films increased.