Preparation and properties of (Ba/sub x/Sr/sub 1-x/)TiO/sub 3/ thin film for high density DRAM application

BST thin film is thought as the best candidate to substitute for SiO/sub 2/ thin film in high density DRAM application due to its high dielectric constant and low leakage current property. In this paper, (Ba/sub x/Sr/sub 1-x/)TiO/sub 3/ (x=0-1) thin films with pure perovskite phase and good surface morphology were successfully prepared by the MOD method, in which acetates and titanium(IV) isopropoxide were used as source materials while acetic acid and ethylene glycol ethyl were used as solvents. The films were heated by two steps pyrolysis and annealing. The precursor and the gel heated at different temperatures were analyzed by thermal analysis and infrared absorption spectroscopy analysis to ascertain mechanism of the heating process and choose an appropriate heating condition. The phase-formation characteristics of the films were investigated by X-ray diffraction. For the film prepared under the optimized condition, dielectric constant distributed between 1036 and 340 when frequency varied from 10 kHz to 3 MHz.