Controller and Estimator Design for Regulation of Film Thickness, Surface Roughness, and Porosity in a Multiscale Thin Film Growth Process

This work focuses on simultaneous regulation of film thickness, surface roughness, and porosity in a multiscale model of a thin film growth process using the inlet precursor concentration as the manipulated input. Specifically, under the assumption of continuum, a partial differential equation model is first derived to describe the dynamics of the precursor concentration in the gas phase. The thin film growth process is modeled via a microscopic kinetic Monte Carlo simulation model on a triangular lattice with vacancies and overhangs allowed to develop inside the film. Closed-form dynamic models of the thin film surface profile and porosity are developed and used as the basis for the design of model predictive control algorithms to simultaneously regulate film thickness, surface roughness, and porosity. Both state feedback and porosity estimation-based output feedback control algorithms are presented. Simulation results demonstrate the applicability and effectiveness of the proposed modeling and control approach by applying the proposed controllers to the multiscale model of the thin film growth process.