Improved homogeneity of plasma and coating properties using a lance matrix gas distribution in MW-PECVD

Plasma reactors for the application of silicon oxide coatings (SiOx) are often customized to optimize the processes regarding substrate properties and targeted functionalities. The design of these reactors is often based on qualitative considerations. This paper evaluates the use of a numerical, free simulation software for continuous mechanical problems (OpenFOAM) as a tool to evaluate reactor design options. As demonstrator for this purpose serves a given reactor for large-area pulsed microwave plasmas with a precursor inlet in the form of a shower ring. Previous results indicate that the shower ring may lead to an inhomogeneity in plasma and coatings properties along the substrate surface. Thus, a new precursor inlet design shall be developed. For this, the distribution of the process gases in the reactor for a variety of gas inlet designs and gas flows was simulated and a design chosen based on the results. The reactor was modified accordingly, and the simulations correlated with experimental results of plasma and coating properties. The results show that, despite many simplifications, a simulation of the neutral gas distribution using an open-access software can be a viable tool to support reactor and process design development.