DEPOSITION CHARACTERISTICS OF (BA, SR)TIO3 THIN-FILMS BY LIQUID SOURCE METAL-ORGANIC CHEMICAL-VAPOR-DEPOSITION AT LOW SUBSTRATE TEMPERATURES

The deposition characteristics of (Ha, Sr)TiO3 (BST) thin films using a liquid source metal-organic chemical vapor deposition on a 6-inch-di ameter Pt/SiO2/Si wafer were investigated. Ba(DPM)(2)tetraglyme, Sr(DP M)(2)tetraglyme and Ti(DPM)(2)(O+Pr)(2), dissolved in n-butyl acetate, were used as the sources of Ha, Sr and Ti, respectively. Step coverag e, within-wafer uniformities in composition and thickness of the BST f ilms were investigated as a function of substrate temperatures ranging from 420 degrees C to 570 degrees C. As the substrate temperature dec reased, the step coverage improved, whereas the within-wafer uniformit ies degraded. From BST films deposited in a temperature range from 450 degrees C to 480 degrees C, good step coverage (>80%), as well as goo d within-wafer uniformity were obtained. However, in that temperature range, hazy deposition was observed due to many humps on the surface. The humps are an agglomeration of crystalline grains and are a few hun dred A in diameter, which have a Ti-rich composition compared to fiat him region.