Method and apparatus of synthesizing diamond in vapor phaase

摘要

A DC plasma jet method enables us to synthesize diamond at a high speed by spraying an activated carbon-containing gas as a plasma jet to a substrate. Despite the high speed deposition, the method cannot synthesize a wide uniform diamond owing to the ununiformity of the jet and the restriction of sizes of torches. Uniform deposition of diamond on a wide substrate is a purpose of this invention. More than two anode-nozzles and more than one plasma torch are utilized. They are disposed with their center lines crossing at a point. An inert gas or hydrogen gas are supplied in the torches in order to excite inner arc plasma jets. Then the torches are applied a negative DC voltage. The anode-nozzles are applied a positive voltage and are supplied with an inert gas, hydrogen gas or both an inert gas and hydrogen gas. Outer transferable plasma jets are formed between the cathodes of torches as cathodes and the nozzles as anodes. The plasma arc jets are integrated into a unified plasma flame. The nozzles and the torches are moved or rotated in order to enlarge the plasma formation areas. A carbon-containing gas is supplied to confluences of the plasma jets from the cathode-torches and the anode-nozzles from gas supplying nozzles.