Preparation and Electrical Properties of BST Thin Films Deposited by Liquid Source Misted Chemical Vapor Depositon(LSMCVD)

Abstract

(Ba,Sr)TiO3(BST) thin films were grown on platinized Si wafer by LSMCVD. The electrical properties of BST films were investigated on Pt/SiO2/Si and Pt/Ti/SiO2/Si. BST thin films were deposited at room temperature and pressure of 700Torr followed by prebaking step at 240oC and baking step at 500oC. Top electrode with area of 1.24x10-3cm2 were fabricated by rf sputter-deposition of 100nm-thick Pt film on the BST film. The fabricated capacitors were postannealed at 750oC to increase the crystallinity. The dielectric constant of 212 and the leakage current densities of 5.8X10-7A/cm2 at +1.1V were achieved at the thickness of 115nm. The significant increase in leakage current and the short failure of BST thin films was arising from the formation of hillock of bottom electrode Pt, which was verified in the photographs of TEM, SEM, and AFM during heat treatment. Especially, the electric properties of BST films was improved by the various conditions of heat treatments(temperature, ambient gas).