Low temperature metal-organic chemical vapor deposition of (Ba,Sr)TiO3 thin films for capacitor applications

Low temperature metal-organic chemical vapor deposition (MOCVD) processes for producing high dielectric (Ba,Sr)TiO3 (BST) films studied using a noble dome type reactor, liquid delivery technique and new precursors. One of the problems associated with conventional MOCVD reactors having a shower head was substrate surface-dependent deposition of film composition as well as the thickness. which might result in pattern-dependent deposition of BST films. The new chamber used in this study was capable of controlling both the substrate heater and chamber wall temperatures which successfully eliminated such surface-dependent deposition property. The film composition and thickness were essentially the same on either Pt and SiO2 surfaces when both the wall and heater temperatures were controlled. However, the film composition, thickness and uniformity were differed markedly on the Pt and SiO2 surfaces when only the heater temperature was controlled. Excellent step coverage and smooth (haze-free) surface morpholgy of BST films were obtained from a deposition at 470 degreesC.