Reduced order modeling and control of thin film growth in an HPCVD reactor (Q2783754)

The authors describe a reduced order model-based feedback control methodology for regulation of the growth of thin films in a High-Pressure Chemical Vapor Deposition (HPCVD) reactor. Precise control of the film thickness and composition is highly desirable, thus, real-time control of the deposition is also very important. The source vapor species transport is modeled by the standard gas dynamics partial differential equations, with species decomposition reactions, which are reduced down to a system of ordinal differential equations by use of the proper orthogonal decomposition technique. The utilization of reduced order models greatly simplifies the mathematical formulation of the physical process, so that it can be solved quickly enough to be used for real-time model-based feedback control. The authors use a nonlinear feedback control method based on the state-dependent Riccati equation (SDRE). A second SDRE is contained in a state estimator which uses the nonlinear partial observations of the growth process. These nonlinear control techniques are implemented on the HPCVD model, and the results are analyzed as to the effectiveness of the reduced order model and the nonlinear control at tracking the desired film growth profile.