Selection of crystal orientation in diamond film chemical vapor deposition

Abstract

In depositing an adhering, continuous, polycrystalline diamond film on a substrate by forming a refractory nitride interlayer on the substrate and depositing diamond on the interlayer in a vacuum chamber containing a microwave activated mixture of hydrogen and a gas including carbon, the crystal orientation of the deposited diamond, <111> or <100>, is selected by controlling the pressure in the chamber. Preferably, relatively higher microwave power is utilized at higher pressures.

What is claimed is: 
     
       1. A method for forming diamond crystallites, the method comprising: providing a refractory nitride material having a surface;   depositing said diamond directly on said surface by chemical vapor deposition from an activated gaseous mixture including hydrogen and a gas containing carbon; and   controlling the pressure of said gaseous mixture during said vapor deposition so that said crystallites have preferred crystal orientation.   
     
     
       2. The method of claim 1 wherein said pressure is less than about 30 torr so that said orientation is the <100> crystal orientation. 
     
     
       3. The method of claim 1 wherein said pressure is greater than about 30 torr so that said orientation is the <111> crystal orientation. 
     
     
       4. The method of claim 1 wherein said nitride has a thickness of at least 500 angstrom units and wherein the method further comprises activating said mixture by microwave energy while maintaining said surface at a temperature in the range of about 600 to about 1100 degrees centigrade and maintaining said pressure below about 100 torr. 
     
     
       5. The method of claim 4 wherein said pressure is less than 30 torr so that said orientation is the <100> crystal orientation. 
     
     
       6. The method of claim 4 wherein said pressure is greater than 30 torr so that said orientation is the <111> crystal orientation. 
     
     
       7. In a method for depositing a film of diamond crystallites on a substrate from an activated gas providing carbon from which said crystallites are formed, an improvement for depositing said crystallites with a predetermined crystal orientation wherein the improvement comprises selecting the pressure of said gas so as to determine said crystal orientation. 
     
     
       8. The method of claim 7 wherein said crystallites are deposited on a refractory nitride material. 
     
     
       9. The improvement of claim 8: wherein in said method, said gas consists of hydrogen and a compound including said carbon, and said substrate is maintained at a temperature in a range of 600 degrees to 1100 degrees centigrade; and   wherein said improvement further comprises selecting said pressure below about 30 torr so as to preferentially deposit said crystallites having the <100> orientation.   
     
     
       10. The improvement of claim 8: wherein in said method, said gas consists of hydrogen and a compound including said carbon, and said substrate is maintained at a temperature in a range of 600 degrees to 1100 degrees centigrade; and   wherein said improvement further comprises selecting said pressure above about 30 torr so as to preferentially deposit said crystallites having the <111> orientation.