Microwave plasma enhanced chemical vapour deposition (PECVD) of thin films is the preferred technology when highest deposition rates are desirable. However, large area applications have always suffered from poor film thickness uniformity and unacceptable variations of thin film properties. Coaxial plasma line sources in various arrangements have recently proven their ability to overcome most limitations, which prevented microwave PECVD of becoming a mainstream technology in the field of large area coatings. In this article, the advantages and the potential of the coaxial plasma line sources and suitable vacuum processes are discussed in detail. (c) 2005 Elsevier B.V. All rights reserved.