Plasma-enhanced chemical vapor deposition (PECVD) using microwave or high frequency (HF) plasma is an established process for depositing silicon-based polymer layers for various applications. Vapor-phase monomers enter a reaction chamber and are ionized, excited, or decomposed by a plasma. The fragments then deposit on the substrate surface. Compared to chemically crosslinked polymers, the layers have higher density, greater hardness, and provide a higher barrier effect. The method is especially suitable for coating large surfaces of thermally sensitive materials. For example, permeation barrier layers and optical layers / layer systems can be deposited on plastic films. The layer properties can be relatively easily varied by modifying the plasma excitation and by changing the composition of the process gas.
The Fraunhofer FEP has developed a number of variants of the plasma-enhanced process. The magnetron variant (magPECVD) has the advantage that it gives good layer homogeneity and allows high coating rates on large areas. Also, the process can be readily combined with other coating processes such as magnetron sputtering because it operates at the same process pressure.
arcPECVD gives very dense plasmas, and this allows very high coating rates to be achieved. The process pressure can be varied over a broad range, meaning the process is also compatible with other vacuum coating technologies.
A feature of high frequency PECVD is the even greater range of process pressure. A very wide range of monomers can be used for this technique.