Silicon carbide epitaxial layers grown on substrates offcut towards

• US 6,329,088 B1
• Filed: 06/24/1999
• Issued: 12/11/2001
• Est. Priority Date: 06/24/1999
• Status: Expired due to Term

• Current Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Original Assignee: Advanced Technology Materials, Inc. (Entegris Incorporated)
• Inventors: Brandes, George R., Tischler, Michael A., Landini, Barbara E.
• Primary Examiner(s): Jones, Deborah
• Assistant Examiner(s): STEIN, STEPHEN J
• Application Number:
  US09/339,510
• Time in Patent Office: 901 Days
• Field of Search: 428/698, 428/699, 428/700, 428/446, 428/450, 117/951, 117/2, 117/88, 423/345
• US Class Current: 428/698
• CPC Class Codes: C30B 25/02 Epitaxial-layer growth
• CPC Class Codes: C30B 29/36 Carbides
• CPC Class Codes: H01L 21/02378 Silicon carbide
• CPC Class Codes: H01L 21/02433 Crystal orientation
• CPC Class Codes: H01L 21/02529 Silicon carbide
• CPC Class Codes: H01L 21/02576 N-type
• CPC Class Codes: H01L 21/02579 P-type
• CPC Class Codes: H01L 21/02581 Transition metal or rare earth elements
• CPC Class Codes: H01L 21/02587 Structure
• CPC Class Codes: H01L 21/0262 Reduction or decomposition of gaseous compounds, e.g. CVD
• CPC Class Codes: H01L 29/045 by their particular orientation of crystalline planes
• CPC Class Codes: H01L 29/1608 Silicon carbide
• CPC Class Codes: Y10T 428/24777 Edge feature
• CPC Class Codes: Y10T 428/30 Self-sustaining carbon mass or layer with impregnant or other layer

Abstract

A silicon carbide epitaxial film, grown on an offcut surface of a SiC crystalline substrate of hexagonal crystal form, having an offcut angle of from about 6 to about 10 degrees, toward the <1{overscore (1)}00> crystalline direction of the substrate. The resultant silicon carbide epitaxial film has superior morphological and material properties.

Claims

1. An epitaxial SiC film, grown on an offcut surface of a SiC substrate having a hexagonal structure, with the offcut surface having an offcut angle of from about 2 to about 10 degrees, and the crystallographic direction of the offcut surface being towards one of the six equivalent <

1{overscore (1)}00>

directions of the substrate ±

7.5 degrees, wherein said epitaxial SiC film comprises a device quality SiC film having a smooth surface morphology, within an edge exclusion area, and having a root mean square roughness not exceeding about 2 nanometers in a 20×

20 μ

m² area.

2. The epitaxial SiC film of claim 1, wherein the SiC substrate comprises 4H—

SiC.

3. The epitaxial SiC film of claim 1, wherein the SiC substrate comprises 6H—

SiC.

4. The epitaxial SiC film of claim 1, wherein said epitaxial SiC film has a root mean square roughness of less than 1 nanometer in a 20×

20 μ

m² area.

5. The epitaxial SiC film of claim 1, wherein the offcut angle is from about 7 to about 9 degrees.

6. The epitaxial SiC film of claim 1, wherein the offcut angle is about 8 degrees.

7. The epitaxial SiC film of claim 1, wherein the offcut direction is towards one of the six equivalent <

1{overscore (1)}00>

directions ±

5 degrees.

8. The epitaxial SiC film of claim 1, wherein the offcut direction is towards one of the six equivalent <

1{overscore (1)}00>

directions ±

2.5 degrees.

9. The epitaxial SiC film of claim 1, wherein the offcut direction is towards one of the six equivalent <

1{overscore (1)}00>

directions ±

1.5 degrees.

10. The epitaxial SiC film of claim 1, doped with an n-type and/or p-type dopant species.

11. The epitaxial SiC film of claim 1, doped with an n-type dopant species and/or a p-type dopant species.

12. The epitaxial SiC film of claim 1, doped with a dopant species at a dopant concentration of from about 1×

10¹³ to about 1×

10²¹ atoms·

cm<sup>−

3</sup>.

13. The epitaxial SiC film of claim 1, doped with a dopant species at a dopant concentration of from about 1×

10¹⁸ to about 1×

10²¹ atoms·

cm<sup>−

3</sup>.

14. The epitaxial SiC film of claim 1, doped with a dopant species at a dopant concentration of from about 1×

10¹⁹ to about 1×

10²¹ atoms·

cm<sup>−

3</sup> .

15. The epitaxial SiC film of claim 1, having a microelectronic device structure formed on or in the film.

16. The epitaxial SiC film of claim 1, wherein said epitaxial SiC film has no large-scale step bunching.

17. A silicon carbide article, comprising:

a SiC substrate of hexagonal crystal form, with an offcut surface having an offcut angle of from about 2 to about 10 degrees, and the crystallographic direction of the offcut surface being towards one of the six equivalent <

1{overscore (1)}00>

directions of the substrate ±

7.5 degrees; and

an epitaxial SiC film, grown on the offcut surface, wherein said epitaxial SiC film comprises a device quality epitaxial SiC film having a smooth surface morphology, within an edge exclusion area, and having a root mean square roughness of not exceeding 2 nanometers in a 20×

20 μ

m² area.

18. The silicon carbide article of claim 17, wherein the SiC substrate comprises 4H—

SiC.

19. The silicon carbide article of claim 17, wherein the SiC substrate comprises 6H—

SiC.

20. The silicon carbide article of claim 17, wherein the epitaxial SiC film has a root mean square roughness of less than 1 nanometers in a 20×

20 μ

m² area.

21. The silicon carbide article of claim 17, wherein the offcut angle is from about 7 to about 9 degrees.

22. The silicon carbide article of claim 17, wherein the offcut angle is about 8 degrees.

23. The silicon carbide article of claim 17, wherein the offcut direction is towards one of the six equivalent <

1{overscore (1)}00>

directions ±

5 degrees.

24. The silicon carbide article of claim 17, wherein the offcut direction is towards one of the six equivalent <

1{overscore (1)}00>

directions ±

2.5 degrees.

25. The silicon carbide article of claim 17, wherein the offcut direction is towards one of the six equivalent <

1{overscore (1)}00>

directions ±

1.5 degrees.

26. The silicon carbide article of claim 17, wherein the epitaxial SiC film is doped with an n-type and/or p-type dopant species.

27. The silicon carbide article of claim 17, wherein the epitaxial SiC film is doped with an in-type dopant species and/or a p-type dopant species.

28. The silicon carbide article of claim 17, wherein the epitaxial SiC film is doped with a dopant species at a dopant concentration of from about 1×

10¹³ to about 1×

10²¹ atoms·

cm<sup>−

3</sup>.

29. The silicon carbide article of claim 17, wherein the epitaxial SiC film is doped with a dopant species at a dopant concentration of from about 1×

10¹⁸ to about 1×

10²¹ atoms·

cm<sup>−

3</sup>.

30. The silicon carbide article of claim 17, wherein the epitaxial SiC film is doped with a dopant species at a dopant concentration of from about 1×

10¹⁹ to about 1×

10²¹ atoms·

cm<sup>−

3</sup>.

31. The silicon carbide article of claim 17, comprising a microelectronic device structure formed on or in the epitaxial SiC film.

32. A silicon carbide epitaxial material, grown on a (0001) 4H—

SiC crystalline substrate offcut towards the <

1{overscore (1)}00>

crystalline direction of the substrate, wherein said silicon carbide epitaxial material has a smooth surface morphology, within an edge exclusion area, and having a root mean square roughness not exceeding about 2 naniometers in a 20×

20 μ

m² area.

33. The silicon carbide epitaxial material of claim 32, wherein the (0001 ) 4H—

SiC crystalline substrate has an offcut angle of from about 7 to about 9 degrees towards the <

1{overscore (1)}00>

crystalline direction of the substrate.

34. The silicon carbide epitaxial material of claim 32, wherein the (0001) 4H—

SiC crystalline substrate has an offcut angle of about 8 degrees towards the <

1{overscore (1)}00>

crystalline direction of the substrate.

35. The silicon carbide epitaxial material of claim 32, doped with an n-type and/or a p-type dopant species at a dopant concentration of from about 1×

10¹⁸ to about 1×

10²¹ atoms·

cm<sup>−

3</sup>.

36. A 4H—

SiC epilayer film grown on a (0001) 4H—

SiC substrate offcut towards the <

1{overscore (1)}00>

crystalline direction of the substrate, wherein said epilayer film has a LEED (0{overscore (1)}) beam intensity profile as shown in FIG. 2.

37. A 4H—

SiC epilayers film grown on a (0001) 4H—

SiC substrate offcut towards the <

1{overscore (1)}00>

crystalline direction of the substrate, wherein said epilayers film has an average root mean square roughness less than 0.8 nanometers in a 20×

20 μ

m² area.

38. A silicon carbide article comprising a 4H—

SiC epitaxial material on a (0001) 4H—

SiC single crystal substrate offcut towards the <

1{overscore (1)}00>

crystalline direction of the substrate, wherein said 4H—

SiC epitaxial material has a smooth surface morphology, within an edge exclusion area, and having a root mean square roughness not exceeding about 2 nanometers in a 20×

20 μ

m² area.

39. The silicon carbide article of claim 38, wherein the (0001) 4H—

SiC single crystal substrate has an offcut angle of from about 7 to about 9 degrees towards the <

1{overscore (1)}00>

crystalline direction of the substrate.

40. The silicon carbide article of claim 38, wherein the (0001) 4H—

SiC single crystal substrate has an offcut angle of about 8 degrees towards the <

1{overscore (1)}00>

crystalline direction of the substrate.

41. The silicon carbide article of claim 38, wherein the 4H—

SiC epitaxial material is doped with an n-type and/or a p-type dopant species at a dopant concentration of from about 1×

10¹⁸ to about 1×

10²¹ atoms·

cm<sup>−

3</sup>.

42. A silicon carbide article comprising a 4H—

SiC epilayer film growing on a (0001) 4H—

SiC substrate offcut towards the <

1{overscore (1)}00>

crystalline direction of the substrate, having a LEED (0{overscore (1)}) beam intensity profile as shown in FIG. 2.

43. A silicon carbide article comprising a 4H—

SiC epilayers film grown on a (0001) 4H—

SiC substrate offcut towards the <

1{overscore (1)}00>

crystalline direction of the substrate, having an average root mean square roughness less than about 0.8 nanometers in a 20×

20 μ

m² area.

44. A method of forming a device quality silicon carbide epitaxial film, comprising depositing said film at subatmospheric pressure conditions on a silicon carbide substrate of hexagonal crystal form, offcut towards the <

1{overscore (1)}00>

crystalline direction of the substrate, wherein said silicon carbide epitaxial film has a smooth surface morphology, within an edge exclusion area, and has a root mean square roughness not exceeding about 2 nanometers in a 20×

20 μ

m² area.

45. The method of claim 44, wherein the silicon carbide substrate comprises 4H—

SiC.

46. The method of claim 44, wherein the silicon carbide substrate comprises 6H—

SiC.

47. The method of claim 44, wherein the offcut angle is from about 7 to about 9 degrees.

48. The method of claim 44, wherein the offcut angle is about 8 degrees.

49. The method of claim 44, wherein the offcut direction is towards one of the six equivalent <

1{overscore (1)}00>

directions ±

5 degrees.

50. The method of claim 44, wherein the offcut direction is towards one of the six equivalent <

1{overscore (1)}00>

directions ±

2.5 degrees.

51. The method of claim 44, wherein the offcut direction is towards one of the six equivalent <

1{overscore (1)}00>

directions ±

1.5 degrees.

52. The method of claim 44, further comprising doping the silicon carbide epitaxial film with an n-type and/or p-type dopant species at a dopant concentration of from about 1×

10¹⁷ to about 1×

10²¹ atoms·

cm<sup>−

3</sup>.

53. The method of claim 52, wherein the silicon carbide epitaxial film is doped to a dopant concentration of from about 1×

10¹⁹ to about 1×

10²¹ atoms·

cm<sup>−

3</sup>.

54. A method of forming a device quality silicon carbide epitaxial film, comprising depositing said film at subatmospheric pressure conditions on a (0001) 4H—

SiC crystalline substrate offcut towards the <

1{overscore (1)}00>

crystalline direction of the substrate, wherein said silicon carbide epitaxial film has a smooth surface morphology, within an edge exclusion area, and has a root mean square roughness not exceeding about 2 nanometers in a 20×

20 μ

m² area.

55. The method of claim 54, wherein the (0001) 4H—

SiC single crystal substrate has an offcut angle of from about 7 to about 9 degrees towards the <

1{overscore (1)}00>

crystalline direction of the substrate.

56. The method of claim 54, wherein the (0001) 4H—

SiC single crystal substrate has an offcut angle of about 8 degrees towards the <

1{overscore (1)}00>

crystalline direction of the substrate.

57. The method of claim 54, wherein growth of said film is carried out using SiH₄ and C₄ with a H₂ carrier gas as a gaseous source medium for said film deposition.

58. The method of claim 57, wherein growth of said film is carried out under growth conditions including temperature in the range of from about 1450 to about 1650°

C.

59. The method of claim 57, wherein intentional in-situ doping of said film is carried out during growth of said film.

60. The method of claim 59, wherein doping is conducted with a dopant source for a dopant species selected from the group consisting of nitrogen, aluminum, phosphorus, boron, and vanadium.

61. The method of claim 59, wherein doping is conducted using N₂ gas to provide nitrogen as an in-type dopant of the film.

62. The method of claim 59, wherein doping is conducted using triethylaluminum to provide aluminum as a p-type dopant of the film.

63. The method of claim 54, including the step of fabricating an electronic device on the film.

64. A method of forming a device quality silicon carbide epitaxial film, comprising growing said film on a (0001) 4H—

SiC crystalline substrate offcut towards the <

1{overscore (1)}00>

crystalline direction of the substrate, wherein said growing step comprises;

introducing, a carrier gas, a vaporized silicon-containing material and a vaporized carbon-containing material into a growth chamber at subatmosphieric pressure conditions; and

maintaining the carrier gas, silicon-containinig material and carbon-containing material flows and temperature condition for a time sufficient to grow a film of desired thickness,

wherein said film has a smooth surface morphology, within an edge exclusion area, and has a root mean square roughness not exceeding about 2 nanometers in a 20×

20 μ

m² area.