Process for producing an electrical contact on a SIC surface

• US 6,139,624 A
• Filed: 12/19/1997
• Issued: 10/31/2000
• Est. Priority Date: 04/13/1995
• Status: Expired due to Term

• Current Assignee: Infineon Technologies AG
• Original Assignee: Siemens AG
• Inventors: Rupp, Roland
• Primary Examiner(s): Utech, Benjamin L.
• Assistant Examiner(s): ANDERSON, MATTHEW A
• Application Number:
  US08/945,156
• Time in Patent Office: 1,047 Days
• Field of Search: 117/88, 117/2
• US Class Current: 117/2
• CPC Class Codes: H01L 21/045 passivating silicon carbide surfaces
• CPC Class Codes: H01L 21/0495 Schottky electrodes

Abstract

Method for producing an electrical contact on a SiC surface A carbon coating (4), preferably a graphite coating, is first created on the silicon carbide surface (3). Said carbon coating (4) is then converted, with a carbide-forming metal (Me), into a metal carbide coating (7). The SiC/metal carbide contact produced thereby forms, in particular, an almost perfect Schottky contact.

Claims

1. A method for producing an electrical contact on a silicon carbide surface (3), comprising the steps of:

a) producing by epitaxial deposition a SiC crystal (2) having said silicon carbide surface (3);

b) producing a carbon coating (4) on said silicon carbide surface (3) by interrupting silicon delivery during said epitaxial deposition and by delivering only carbon; and

c) converting the carbon coating (4) at least largely into metal carbide with at least one carbide-forming metal.

2. The method as defined in claim 1, wherein the SiC single crystal (2) and the carbon coating (4) are produced by chemical vapor deposition.

3. The method as defined in claim 1, wherein the SiC single crystal (2) and the carbon coating (4) are produced by molecular beam epitaxy.

4. The method as defined in claim 1, wherein the silicon carbide surface (3) is formed with a silicon plane of the SiC single crystal (2) that corresponds in the case of a cubic polytype of SiC (β

-SiC) to a (1 1

     1) crystal surface, and that corresponds in the case of a non-cubic polytype (α

-SiC) to a (0 0 0

     1) crystal surface.

5. The method as defined in claim 1, wherein the silicon carbide surface (3) is formed with a carbon plane of the SiC single crystal (2) that corresponds in the case of a cubic polytype of SiC (β

-SiC) to a (-1 -1 -1) crystal surface, and that corresponds in the case of a non-cubic polytype (α

-SiC) to a (0 0 0 -1) crystal surface.

6. The method as defined in claim 1, wherein the carbon coating (4) has a substantially graphite crystalline structure or a graphite-like crystalline structure.

7. The method as defined in claim 1, wherein the carbon coating (4) is created to have a thickness of less than 1 nm.

8. The method as defined in claim 1, wherein an element selected from the group consisting of tungsten (W), titanium (Ti), tantalum (Ta), boron (B), aluminum (Al), nickel (Ni), and scandium (Sc) is used as the carbide-forming metal.

9. The method as defined in claim 1, wherein the at least one carbide-forming metal is brought to the carbon coating (4) by sputtering.

10. The method as defined in claim 9, wherein the kinetic energy of the metal atoms or metal ions is set to be at least as great as the chemical formation energy of the associated metal carbide.

11. The method as defined in claim 1, wherein the carbide-forming metal is first applied onto the carbon coating (4) and then caused to react chemically with the carbon by means of a temperature treatment.

12. The method as defined in claim 11, wherein the carbide-forming metal is evaporated onto the carbon coating (4).

13. A method for producing an electrical contact on a silicon surface (3), comprising the steps of:

a) producing a SiC crystal (2) by epitaxial deposition at a temperature between approximately 1000°

C. and approximately 1800°

C. said SiC single crystal (2) having said silicon carbide surface (3), immediately followed by

b) cooling the SiC single crystal (2) in vacuum or in an inert gas atmosphere, wherein the carbon coating (4) is produced by evaporating silicon atoms off from said silicon carbide surface (3), and

c) converting the carbon coating (4) at least largely into metal carbide with at least one carbide-forming metal.

14. The method as defined in claim 13, wherein the SiC single crystal (2) is produced by chemical vapour deposition.

15. The method as defined in claim 13, wherein the SiC single crystal (2) is produced by molecular beam epitaxy.

16. The method as defined in claim 13, wherein the silicon carbide surface (3) is formed with a silicon plane of the SiC single crystal (2) that corresponds in the case of a cubic polytype of SiC (β

-SiC) to a (1 1

     1) crystal surface, and that corresponds in the case of a non-cubic polytype (α

-SiC) to a (0 0 0

     1) crystal surface.

17. The method as defined in claim 13, wherein the silicon carbide surface (3) is formed with a carbon plane of the SiC single crystal (2) that corresponds in the case of a cubic polytype of SiC (β

-SiC) to a (--1 -1 -1) crystal surface, and that corresponds in the case of a non-cubic polytype (α

-SiC) to a (0 0 0 -1) crystal surface.

18. The method as defined in claim 13, wherein the carbon coating (4) has a substantially graphite crystalline structure or a graphite-like crystalline structure.

19. The method as defined in claim 13, wherein the carbon coating (4) is created to have a thickness of less than 1 nm.

20. The method as defined in claim 13, wherein an element selected from the group consisting of tungsten (W), titanium (Ti), tantalum (Ta), boron (B), aluminum (Al), nickel (Ni), and scandium (Sc) is used as the carbide-forming metal.

21. The method as defined in claim 13, wherein the at least one carbide-forming metal is brought to the carbon coating (4) by sputtering.

22. The method as defined in claim 21, wherein the kinetic energy of the metal atoms or metal ions is set to be at least as great as the chemical formation energy of the associated metal carbide.

23. The method as defined in claim 13, wherein the carbide-forming metal is first applied onto the carbon coating (4) and then caused to react chemically with the carbon by means of a temperature treatment.

24. The method as defined in claim 23, wherein the carbide-forming metal is evaporated onto the carbon coating (4).