Feedback control of thin film growth in an HPCVD reactor via reduced order models

This paper describes the development of a reduced order model-based feedback control methodology for the regulation of the growth of thin films in a high-pressure chemical vapor deposition (HPCVD) reactor. This is achieved in the context of gas dynamics coupled with a nonlinear reduced order model of the surface reactions involved in the source vapor decomposition and film growth on the substrate. Also modeled is the realtime observation technique used to obtain a partial measurement of the deposition process. The control problems are optimal tracking problems of the film thickness that employ state-dependent Riccati gains with nonlinear observations and the resulting dual state dependent Riccati equations for the compensator gains.