Method for synthesizing diamond

Claim 1

A low pressure vapor phase method of synthesizing diamond from a carbon source ingredient selected from solid carbon, hydrocarbon, hydrocarbon additionally containing O and N in bonded radicals, and carbon tetrachloride, where said method causes raw material gas compound of a mixture of said carbon ingredient and hydrogen to be activated for eventually precipitating diamond on the surface of a substrate heated to a minimum of 600° C. through a maximum of 1,200° C., said method comprising; (a) causing thermoelectron radiating material heated to a minimum of 1,600° C., to activate said raw material gas; (b) generating an electrical potential by connecting said thermoelectron radiating material to a negative electrode and connecting a grid disposed between said thermoelectron radiating material and the substrate to be coated to a positive electrode and applying a DC power supply source to said negative and positive electrodes; (c) extracting thermoelectrons from said thermoelectron radiating material by the electrical potential generated in step (b) to generate a plasma of positive ions between the thermoelectron radiating material and the grid; (d) generating an electrical potential between the grid and the substrate by connecting the substrate to a negative electrode and applying a second DC power supply source for generating plasma between the grid and the substrate while maintaining the potential of said substrate negative relative to the grid to thereby draw positive plasma ions onto the surface of the substrate to form a coating on said surface of the substrate which is heated to a minimum of 600° C. through a maximum of 1,200° C.; (e) jointly applying the effect of activation generated by the thermoelectron radiating material and another activation caused by generation of DC plasma; and (f) maintaining the pressure inside the plasma-generating reactor to between 10 Torr and 400 Torr.