Modeling and Control of MOCVD of Ferroelectric Thin Films

Polycrystalline Barium Strontium Titanate/Oxide (BSTO) films exhibit low dielectric losses and tunable dielectric constants, and can be used as a frequency agile materials for manufacturing RF and microwave communication components. These properties have a strong dependence on stoichiometry and microstructure. Additionally, precise control of composition over a large area and enhanced growth rates are important in reducing manufacturing costs.

A methodology was developed and implemented under this DARPA-funded program to perform reactor-scale physical modeling and model-based process control for barium strontium titanate (Ba_1-xSr_xTiO₃ or BSTO) thin film deposition. This novel approach, demonstrated for the first time on YBCO deposition in an earlier program, began from first-principles quantum chemistry computations led by Stanford University to determine the pathways of the complex chemical processes involved in precursor decomposition and BSTO formation.

We developed an accurate physical model of the chamber for predicting film deposition rate and uniformity. A run-to-run controller was development in conjunction with the modeling effort, and its performance demonstrated using MATLAB™ simulations.

Related Publications

• S. Ghosal, J. L. Ebert, D. de Roover, and A. Emami-Naeini, Model-based Control of MOCVD Rate, Uniformity and Stoichiometry, Presented at the Third Symposium of Process Control, Diagnostics, and Modeling in Semiconductor Manufacturing, 195^th Meeting of the Electrochemical Society, Seattle, May 2-6, 1999.