High velocity method for depositing diamond films from a gaseous phase in SHF discharge plasma and a plasma reactor for carrying out said method

Abstract

The invention relates to carbon deposition by decomposing gaseous compounds with the aid of the SHF discharge plasma and can be used, for example, for producing polycrystalline diamond films (plates), which are used for producing output windows of power SHF sources, for example gyrotrons. Said invention ensures a high speed deposition of the high quality diamond films (having a loss-tangent angle □ equal to or less than 3×10 −5 on supports whose diameter is equal to or higher than 100 mm. For this purpose, a SHF discharge is initiated in a gas mixture which is arranged in a reaction chamber and contains at least hydrogen and hydrocarbon. Afterwards, said gas mixture is activated by producing a stable nonequilibrium plasma with the aid of SHF radiation having a frequency f which is many times higher than a commonly used frequency of 2.45 GHz, for example 30 GHz. In order to localize the plasma, a standing wave is formed near the carrier and plasma layers are formed in the antinodes thereof in such a way that the sizes thereof are adjustable.

1 . In a method of depositing diamond films from a gaseous phase in a plasma of a microwave discharge, when the microwave discharge is formed in a gaseous mixture placed in a reaction chamber and comprising at least hydrogen and hydrocarbon, wherein the gaseous mixture is activated by means of a microwave discharge to form atoms of hydrogen and carbon-containing radicals, and the latter are deposited on the substrate and form a polycrystalline diamond film as the result of surface reactions, the improvement which comprises:
 activating the gaseous mixture so as to increase a density of electrons, Ne, in the plasma by means of creating a stable, non-equilibrium plasma with a power at least 1 kW and frequency f that exceeds a frequency of 2.45 GHz, in the reaction chamber in order to localize the plasma as a standing microwave with nodes near the substrate is formed as a layer over the substrate which plasma is generated and maintained by microwave beams directed at and converging on the standing microwave so as to deposit diamond film on the substrate.   
   
   
       2 . The method of  claim 1  wherein said gaseous mixture is activated by means of increasing electron density Ne by using electromagnetic radiation with its frequency f equal to 30 GHz, and the dimensions of the plasma layers in the nodes of the standing microwave are controlled by changing the profiles and size of a transverse cross-section of the crossing wave beams that form the standing wave. 
   
   
       3 . The method of  claim 1  or  2  wherein four or more of the wave beams that are crossed pairwise are used to form the standing wave. 
   
   
       4 . The method of  claim 1  or  2  wherein two converging crossing wave beams are used to form the standing wave. 
   
   
       5 . The method of  claim 1  or  2  wherein two converging opposite wave beams are used to form the standing wave. 
   
   
       6 . The method of  claim 1  or  2  wherein the wave beam is incident on the substrate and the wave beam is reflected from the substrate to form the standing wave. 
   
   
       7 - 15 . (canceled)