Process for making diamond, doped diamond, diamond-cubic boron nitride composite films

• US 4,816,291 A
• Filed: 08/19/1987
• Issued: 03/28/1989
• Est. Priority Date: 08/19/1987
• Status: Expired due to Term

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Doerr, Hans J., Bunshah, Rointan F., Desphandey, Chandra V.
• Primary Examiner(s): Pianalto, Bernard
• Application Number:
  US07/087,141
• Time in Patent Office: 587 Days
• Field of Search: 427/38, 427/39
• US Class Current: 427/566
• CPC Class Codes: C23C 14/0605 Carbon
• CPC Class Codes: C23C 14/32 by explosion; by evaporation and subsequent ionisation of the vapours , e.g. ion-platingC23C14/34 - C23C14/48 take precedence
• CPC Class Codes: C30B 25/02 Epitaxial-layer growth
• CPC Class Codes: C30B 29/04 Diamond

Abstract

A process and apparatus that may be used for the production of diamond and doped diamond films at high rates by activated reactive vapor deposition. Carbon is evaporated in a vacuum chamber in the presence of atomic hydrogen containing plasma to form diamond precursors which then deposit on a substrate located within the vacuum chamber.

Claims

1. A process for depositing films comprising diamond on a substrate, said process comprising the steps of:

supporting a substrate in a vacuum;

evaporating a source of carbon to produce a carbon vapor in a zone between the source of carbon and the substrate;

introducing a hydrogen containing gas into said zone;

accelerating electrons from an electron source into said zone to ionize said carbon vapor and hydrogen containing gas to form carbon-hydrogen complex precursor molecules in said zone,

depositing said precursor molecules from said zone onto said substrate; and

maintaining said substrate at a temperature sufficient to dissociate said deposited precursor molecules to form said film comprising diamond.

2. A diamond deposition process according to claim 1 wherein said source of carbon is graphite.

3. A diamond deposition process according to claim 2 wherein said graphite is evaporated by an electron beam.

4. A diamond deposition process according to claim 1 wherein said hydrogen containing gas is selected from the group consisting of hydrogen, methane ethane and other hydrocarbon gases.

5. A diamond deposition process according to claim 4 wherein said hydrogen containing gas is a mixture of hydrogen and hydrocarbon gases or a mixture of hydrogen and argon or a mixture of hydrogen, argon and hydrocarbon gases.

6. A diamond deposition process according to claim 1 wherein said substrate is selected from the group consisting of stainless steel, molybdenum, glass, quartz, silicon and aluminum.

7. A diamond deposition process according to claim 1 wherein the temperature of said substrate is maintained at temperatures of between about 600°

C. and 1000°

C.

8. A diamond deposition process according to claim 1 wherein the partial pressure of said hydrogen containing gas is between about 2×

10^-4 torr and 20×

10^-3 torr.

9. A diamond deposition process according to claim 8 wherein said hydrogen containing gas is hydrogen.

10. A diamond deposition process according to claim 1 wherein the electrons which are deflected into said zone are produced by said electron source comprising a heated filament.

11. A diamond deposition process according to claim 10 wherein said filament is tungsten, tantalum, molybdenium or carbon.

12. A diamond deposition process according to claim 1 wherein said electrons are deflected into said zone by accelerating said electrons toward an anode.

13. A diamond deposition process according to claim 10 wherein the electrons generated by said filament are accelerated through said zone toward an anode.

14. A diamond deposition process according to claim 13 wherein the potential at said anode is about 80 volts.

15. A diamond deposition process according to claim 1 wherein said film is doped with p and n type dopants such as aluminum, lithium or boron.

16. A deposition process according to claim 1 wherein a film comprising diamond cubic boron nitride is deposited.

17. A diamond deposition process according to claim 15 wherein a boron containing gas is introduced into said zone to provide a film comprising boron doped diamond.

18. A diamond deposition process according to claim 15 wherein vapor of metal organic compounds such as trimethyl aluminum are introduced into said zone to provide a film comprising aluminum doped diamond.

19. A diamond deposition process according to claim 1 wherein said hydrogen containing gas contains CH₄, nitrogen and hydrogen and boric acid/boric oxide is co-evaporated with said carbon to thereby form a film comprising cubic boron nitride doped diamond.