While various thin-film deposition methods have been explored for BSTO growth, including: sol-gel synthesis, spin-coating and atomic layer epitaxy, the most common way of growing BST thin films is by MOCVD using beta-diketonate-type precursors from a liquid source. As a technique for fabrication of BSTO films, MOCVD offers the potential for growth under highly oxidizing conditions, for large area deposition, scalable for manufacturing, and high throughput. However, the process is highly complex involving flow, heat transfer, and gas-phase and surface chemical kinetics.
The desirable dielectric properties of the polycrystalline BSTO films have strong dependence on film stoichiometry and microstructure, which, in turn, are closely linked to deposition conditions and growth kinetics. For enhanced yield, most of the deposition surface on the wafer must have optimal stoichiometry. Additionally, microstructure is dependent on growth rate and substrate temperature. The optimal growth rate is a complex, non-linear function of wafer and chamber temperatures, and of precursor and oxide spatial concentrations within the chamber. Physical model-based control provides the best solution to all control issues related to BSTO thin film production.