Abstract: A method and apparatus for efficiently depositing a dielectric film with a preselected thickness pattern, in particular, a homogeneous, uniform diamond or diamond-like film, on large area substrates through the use of opposing plasma torches and linearly superimposing of microwave modes within the reaction chamber creating and maintaining an extended linear plasma in close proximity to the substrate surfaces and utilizing laminar flow of the reactant gases in the plasma and over the surfaces. Substrate surfaces can be moved past the opposing torches permitting the coating of large area, rectangularly-shaped substrate surfaces in a simple manner. Alternatively, the plasma horn or horns can be moved across the substrate permitting coating of large area, rectangularly-shaped substrate surfaces.