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

Abstract

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.

Advances in surface modification and functionalization for tailoring the characteristics of thin films and membranes via chemical vapor deposition techniques

“…In UHV‐CVD method, the reactor pressure is kept at extremely low levels to achieve high purity, especially when the precursors can react and generate a binding with the residual gasses. This process is often performed at lower temperatures compared to the conventional CVD techniques, in order to decrease the chance of dopant evaporation 87 . It should be noted that after dopant evaporation, which can happen at high temperatures, it is possible for the evaporated species to return to the surface and change the concentration of dopant.…”

“…This process is often performed at lower temperatures compared to the conventional CVD techniques, in order to decrease the chance of dopant evaporation. 87 It should be noted that after dopant evaporation, which can happen at high temperatures, it is possible for the evaporated species to return to the surface and change the concentration of dopant. In a recent study, Byeon et al well demonstrated the advantageous features of using UHV-CVD compared to LP-CVD for the epitaxial growth of Si and SiGe in the absence of a carrier gas.…”