Method for synthesizing flat diamond film, diamond free-standing film, and polishing method for diamond film

摘要

A flat free-standing diamond film is produced by growing alternately more than 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) of a substrate temperature of 880 DEG C to 950 DEG C and a hydrocarbon ratio of 2.5 vol% to 3.5vol%. The potential-convex films are made by a CVD method under the condition (a) of a substrate temperature of 800 DEG C to 850 DEG 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 the 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. The 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. IMAGE