Toward observable UHVCVD: Modeling of flow dynamics and AAS partial pressure measurement implementation

Ultra-high vacuum chemical vapor deposition is a thin film deposition process that features excellent film purity, but is sensitive to the processing variations (such as, the precursors and their dispensers, the reactor’s initial condition, etc.). In this paper, we present the design of a ultra-high vacuum chemical vapor deposition reactor with in situ partial pressure atomic absorption spectroscopy measurement that improves reproducibility and observability of such a process. Our main contributions are: (i) a conceptual control systems design of ultra-high vacuum chemical vapor deposition; (ii) atomic absorption spectroscopy based sensor design for the real-time in situ partial pressure measurements; (iii) a flux dynamical model; (iv) experimental reactor design; and (v) experimental validation of model components and the atomic absorption spectroscopy measurement technique. Our results show that the proposed sensor systems are able to provide real-time measurements of the partial pressure inside the reactor and our proposed flux dynamical model agrees with the measured partial pressure. The latter allows us to use it in the design of model-based output feedback control of the partial pressure.