UNIFORM AND LARGE-AREA DEPOSITION OF DIAMOND BY CYCLIC THERMAL PLASMA CHEMICAL-VAPOR-DEPOSITION

Cyclic thermal plasma chemical vapor deposition is used to deposit diamond films on the substrates placed on a rotating stage with the plasma torch mounted off axis from the center of rotation. The Ar-H-2-CH4 plasma jet was generated by a 50 kW level hybrid plasma torch under 250 Torr, and the jet could be extended as long as 300 mm from the torch exit. Pure diamond films were successfully deposited on relatively large-area substrates. The thickness variations within a 10 cm2 area were less than 3% in the direction of rotation, and around 70% in the perpendicular direction. Deposition rates were about 1 nm layers per pass. These corresponded to a conversion efficiency of about 2% (1 carat/h) from CH4 to diamond.