Methods of synthesizing and polishing a flat diamond film and free- standing diamond film

摘要

A flat free-standing diamond film is produced by growing alternately at least one pair of a potential-concave diamond layer and a potential- convex diamond layer on a non-diamond substrate and eliminating the substrate. The potential-concave films are made by a CVD method under a condition (b), which is characterized by of a substrate temperature of 880 C. to 950 C. and a hydrocarbon ratio of 2.5 vol % to 3.5 vol %. The potential-convex films are made by a CVD method under the condition (a) which is charcterized by of a substrate temperature of 800. degree. C. to 850 C. and a hydrocarbon ratio of 0.5 vol % to 1.5 vol %. The condition (a) can make a potential-convex film of a good crystal quality in spite of a slow deposition speed. It is preferable to employ an assembly of thinner potential-convex films and thicker potential-concave films to curtail the total time of synthesis. A multilayered diamond film with an arbitrary curvature can be produced by selecting the production conditions (a) and (b), and the thicknesses of the potential-convex layers and the potential-concave layers.P PThe diamond films still fixed on the substrate can be polished by an ordinary polishing apparatus, since the film is flat. A polished flat diamond film can be obtained by eliminating the substrate.