Microwave field effect transistor structure on silicon carbide substrate

• US 6,521,923 B1
• Filed: 05/25/2002
• Issued: 02/18/2003
• Est. Priority Date: 05/25/2002
• Status: Expired due to Term

• Current Assignee: Qorvo US, Inc. (Qorvo, Inc.)
• Original Assignee: Sirenza Microdevices, Inc. (Qorvo, Inc.)
• Inventors: D'Anna, Pablo, Johnson, Joseph H.
• Primary Examiner(s): CLARK, JASMINE JHIHAN B
• Application Number:
  US10/156,221
• Time in Patent Office: 269 Days
• Field of Search: 257/288, 257/285, 257/213, 257/275, 257/341, 257/368, 257/389, 257/508, 257/77
• US Class Current: 257/288
• CPC Class Codes: H01L 21/743 Making of internal connections, substrate contacts
• CPC Class Codes: H01L 23/552 Protection against radiation, e.g. light or electromagnetic waves
• CPC Class Codes: H01L 29/0847 of field-effect transistors with insulated gate H01L29/0653 takes precedence; with a passive supplementary region between source or drain and substrate related to punch-through, capacity or isolation phenomena H01L29/1079; with LDD or DDD structure H01L29/7833; for thin film transistors H01L29/78618
• CPC Class Codes: H01L 29/1608 Silicon carbide
• CPC Class Codes: H01L 29/402 Field plates
• CPC Class Codes: H01L 29/4175 for lateral devices where the connection to the source or drain region is done through at least one part of the semiconductor substrate thickness, e.g. with connecting sink or with via-hole
• CPC Class Codes: H01L 29/41766 with at least part of the source or drain electrode having contact below the semiconductor surface, e.g. the source or drain electrode formed at least partially in a groove or with inclusions of conductor inside the semiconductor H01L29/41733 - H01L29/41758 take precedence
• CPC Class Codes: H01L 29/7835 with asymmetrical source and drain regions, e.g. lateral high-voltage MISFETs with drain offset region, extended drain MISFETs
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

A microwave transistor structure comprising: (a) a SiC substrate having a top surface; (b) a silicon semiconductor material of a first conductivity type overlaying the top surface of the semiconductor substrate and having a top surface; (c) a conductive gate overlying and insulated from the top surface of the silicon semiconductor material; (d) a channel region of the first conductivity type formed completely within the silicon semiconductor material including a channel dopant concentration; (e) a drain region of the second conductivity type formed in the silicon semiconductor material and contacting the channel region; (f) a body region of the first conductivity type and having a body region dopant concentration formed in the silicon semiconductor material under the conductive gate region; (g) a source region of the second conductivity type and having a source region dopant concentration formed in the silicon semiconductor material within the body region; (h) a shield plate region being adjacent and being parallel to the drain region formed on the top surface of the silicon semiconductor material over a portion of the channel region; wherein the shield plate region is adjacent and parallel to the conductive gate region; and wherein the shield plate extends above the top surface of the silicon semiconductor material to a shield plate height level, and is insulated from the top-surface of the silicon semiconductor material; and (i) a conductive plug region formed in the body region of the silicon semiconductor material to connect a lateral surface of the body region to the top surface of the substrate.

Claims

1. A microwave transistor structure comprising:

a silicon carbide substrate;

a silicon semiconductor material having a top surface;

said silicon semiconductor material overlaying said silicon carbide substrate;

a conductive gate overlying and insulated from said top surface of said silicon semiconductor material;

a channel region formed completely within said silicon semiconductor material of said first conductivity type, said channel region being of a second conductivity type and having a channel region dopant concentration;

a drain region formed in said silicon semiconductor material, said drain region being of said second conductivity type and having a drain dopant concentration greater than said channel region dopant concentration;

said drain region contacting said channel region;

a body region formed in said silicon semiconductor material, said body region being of said first conductivity type and having a body region dopant concentration, said body region dopant concentration being equal or greater than said first dopant concentration, said body region having a first end underlying said conductive gate, any remaining portion of said silicon semiconductor material underlying said gate being of said first conductivity type;

a source region formed in said silicon semiconductor material, said source region being of said second conductivity type and having a source region dopant concentration, said source region being located within said body region;

a shield plate region formed on said top surface of said silicon semiconductor material over a portion of said channel region, said shield plate being adjacent and parallel to said drain region;

said shield plate being adjacent and parallel to said conductive gate region;

said shield plate extending above said top surface of said silicon semiconductor material to a shield plate height level, said shield plate being insulated from said top surface of said silicon semiconductor material; and

a conductive plug region formed in said body region of said silicon semiconductor material, wherein said conductive plug region connects a lateral surface of said body region to said top surface of said substrate.

2. The microwave transistor structure of claim 1, wherein said channel region further includes:

a first region formed completely within said silicon semiconductor material of said first conductivity type, said first region being of a second conductivity type to form a first enhanced drain drift region of said microwave transistor structure and having a first drain drift region dopant concentration; and

a second region formed in said silicon semiconductor material of said first conductivity type, said second region being of said second conductivity type to form a second enhanced drain drift region of said microwave transistor and having a second drain drift dopant concentration, said second enhanced drain drift region contacting said first enhanced drain drift region, said second enhanced drain drift region dopant concentration being greater than said first enhanced drain drift region dopant concentration;

said drain region having a drain dopant concentration greater than said second enhanced drain region dopant concentration;

said drain region contacting said second enhanced drain drift region.

3. The microwave transistor structure of claim 1, wherein said channel region further comprises:

a first enhanced drain drift region formed completely within said semiconductor material to a first depth level, said first enhanced drain drift region being of said second conductivity type, and having a first enhanced drain drift region dopant concentration;

a second enhanced drain drift region formed completely within said semiconductor material to a second depth level, said second enhanced drain drift region being of said second conductivity type, and having a second enhanced drain drift region dopant concentration, said second enhanced drain region contacting said first enhanced drain region;

said second enhanced drain drift region dopant concentration being greater than said first enhanced drain drift region dopant concentration; and

a third enhanced drain drift region formed completely within said semiconductor material to a third depth level, said third enhanced drain drift region being of said second conductivity type, and having a third enhanced drain drift region dopant concentration, said third enhanced drain drift region contacting said second enhanced drain drift region;

said third enhanced drain drift region dopant concentration being greater than said second enhanced drain drift region dopant concentration;

said drain region having a drain dopant concentration greater than said third enhanced drain region dopant concentration;

said drain region contacting said third enhanced drain drift region.

4. The microwave transistor structure of claim 1, wherein said channel region further comprises:

a first enhanced drain drift region formed completely within said semiconductor material to a first depth level, said first enhanced drain drift region being of said second conductivity type, and having a first enhanced drain drift region dopant concentration;

a second enhanced drain drift region formed completely within said semiconductor material to a second depth level, said second enhanced drain drift region being of said second conductivity type, and having a second enhanced drain drift region dopant concentration, said second enhanced drain drift region contacting said first enhanced drain drift region;

said second enhanced drain drift region dopant concentration being greater than said first enhanced drain drift region dopant concentration;

a third enhanced drain drift region formed completely within said semiconductor material to a third depth level, said third enhanced drain drift region being of said second conductivity type, and having a third enhanced drain drift region dopant concentration, said third enhanced drain region contacting said second enhanced drain region;

said third enhanced drain drift region dopant concentration being greater than said second enhanced drain drift region dopant concentration; and

a fourth enhanced drain drift region formed completely within said semiconductor material to a fourth depth level, said fourth enhanced drain drift region being of said second conductivity type, and having a fourth enhanced drain drift region dopant concentration, said fourth enhanced drain drift region contacting said third enhanced drain drift region;

said fourth enhanced drain drift region dopant concentration being greater than said third enhanced drain drift region dopant concentration;

said drain region having a drain dopant concentration greater than said fourth enhanced drain region dopant concentration;

said drain region contacting said fourth enhanced drain drift region.

5. The microwave transistor structure of claim 1 further including:

a contact enhanced region formed in said silicon semiconductor material, said contact enhanced region being of said first conductivity type and having a contact enhanced region dopant concentration, said contact enhanced region dopant concentration being greater than said body region dopant concentration, said contact enhanced region being located within said body region.

6. The microwave transistor structure of claim 1, wherein said shield plate region further includes:

a shield plate region being connected to said source region.

7. The microwave transistor structure of claim 1, wherein said shield plate region further includes:

a shield plate region being connected to a backside of said structure.

8. The microwave transistor structure of claim 1, wherein said first conductivity type further comprises:

a P type conductivity type.

9. The microwave transistor structure of claim 1, wherein said conductive plug further comprises:

a metal plug.

10. The microwave transistor structure of claim 1, wherein said conductive plug further comprises:

a silicided plug.

11. The microwave transistor structure of claim 1, wherein said silicon carbide substrate further comprises:

a substantially heavily doped silicon carbide substrate; and

wherein said substantially heavily doped silicon carbide substrate provides a thermal path and an electrical path for said microwave transistor.

12. The microwave transistor structure of claim 1, wherein said silicon carbide substrate further comprises:

a substantially lightly doped silicon carbide substrate having a substantially high resistivity; and

wherein said substantially lightly doped silicon carbide substrate having said substantially high resistivity provides a thermal path for said microwave transistor.

13. The microwave transistor structure of claim 1, wherein said conductive gate further comprises:

a highly doped polysilicon gate.

14. The microwave transistor structure of claim 1, wherein said conductive gate further comprises:

a sandwich gate further comprising a highly doped polysilicon bottom layer and a top layer selected from the group consisting of a tungsten silicided, a titanium silicided, a cobalt silicided, and a platinum silicided.

15. The microwave transistor structure of claim 1, wherein said conductive gate further comprises:

a metal gate.

16. The microwave transistor structure of claim 1, wherein said shield plate further comprises:

a metal shield plate.

17. The microwave transistor structure of claim 1, wherein said shield plate further comprises:

a polysilicon shield plate.

18. The microwave transistor structure of claim 1, wherein said shield plate further comprises:

a polysilicon/silicided shield plate sandwich.

19. The microwave transistor structure of claim 1, wherein said shield plate further comprises:

a polysilicon/metal shield plate sandwich.

20. The microwave transistor structure of claim 1, wherein said shield plate further comprises:

a shield plate extending above said top surface of said silicon semiconductor material to said shield plate height, wherein said shield plate height level is in the range of (4,000 Å

-8,000 Å

).

21. The microwave transistor structure of claim 5, wherein said conductive plug region further includes:

a conductive plug region formed in said contact enhanced region and said body region of said silicon semiconductor material, wherein said conductive plug region connects a top surface or a lateral surface of said contact enhanced region and connects a lateral surface of said body region to said top surface of said substrate.

22. The microwave transistor structure of claim 10, wherein said silicided plug is selected from the group consisting of a tungsten silicided plug, a titanium silicided plug, a cobalt silicided plug, and a platinum silicided plug.

23. The microwave transistor structure of claim 11, wherein said silicon carbide substrate further comprises:

a substantially heavily doped silicon carbide substrate having a resistivity lower than 0.1 Ω

cm.

24. The microwave transistor structure of claim 12, wherein said silicon carbide substrate further comprises:

a substantially lightly doped silicon carbide substrate having a resistivity higher than 10³ Ω

cm.

25. A microwave transistor structure comprising:

a silicon carbide substrate;

a bonding layer overlying said silicon carbide substrate;

a silicon semiconductor material having a top surface;

said silicon semiconductor material overlaying said bonding layer;

said silicon semiconductor material bonded to said silicon carbide substrate via said bonding layer;

a conductive gate overlying and insulated from said top surface of said silicon semiconductor material;

a channel region formed completely within said silicon semiconductor material of said first conductivity type, said channel region being of a second conductivity type and having a channel region dopant concentration;

a drain region formed in said silicon semiconductor material, said drain region being of said second conductivity type and having a drain dopant concentration greater than said channel region dopant concentration;

said drain region contacting said channel region;

a body region formed in said silicon semiconductor material, said body region being of said first conductivity type and having a body region dopant concentration, said body region dopant concentration being equal or greater than said first dopant concentration, said body region having a first end underlying said conductive gate, any remaining portion of said silicon semiconductor material underlying said gate being of said first conductivity type;

a source region formed in said silicon semiconductor material, said source region being of said second conductivity type and having a source region dopant concentration, said source region being located within said body region;

a shield plate region formed on said top surface of said silicon semiconductor material over a portion of said channel region, said shield plate being adjacent and parallel to said drain region;

said shield plate being adjacent and parallel to said conductive gate region;

said shield plate extending above said top surface of said silicon semiconductor material to a shield plate height level, said shield plate being insulated from said top surface of said silicon semiconductor material; and

a conductive plug region formed in said body region of said silicon semiconductor material, wherein said conductive plug region connects a lateral surface of said body region to said top surface of said substrate.

26. The microwave transistor structure of claim 25, wherein said channel region further includes:

a first region formed completely within said silicon semiconductor material of said first conductivity type, said first region being of a second conductivity type to form a first enhanced drain drift region of said microwave transistor structure and having a first drain drift region dopant concentration; and

a second region formed in said silicon semiconductor material of said first conductivity type, said second region being of said second conductivity type to form a second enhanced drain drift region of said microwave transistor and having a second drain drift dopant concentration, said second enhanced drain drift region contacting said first enhanced drain drift region, said second enhanced drain drift region dopant concentration being greater than said first enhanced drain drift region dopant concentration;

said drain region having a drain dopant concentration greater than said second enhanced drain region dopant concentration;

said drain region contacting said second enhanced drain drift region.

27. The microwave transistor structure of claim 25, wherein said channel region further comprises:

a first enhanced drain drift region formed completely within said semiconductor material to a first depth level, said first enhanced drain drift region being of said second conductivity type, and having a first enhanced drain drift region dopant concentration;

a second enhanced drain drift region formed completely within said semiconductor material to a second depth level, said second enhanced drain drift region being of said second conductivity type, and having a second enhanced drain drift region dopant concentration, said second enhanced drain region contacting said first enhanced drain region;

said second enhanced drain drift region dopant concentration being greater than said first enhanced drain drift region dopant concentration; and

a third enhanced drain drift region formed completely within said semiconductor material to a third depth level, said third enhanced drain drift region being of said second conductivity type, and having a third enhanced drain drift region dopant concentration, said third enhanced drain drift region contacting said second enhanced drain drift region;

said third enhanced drain drift region dopant concentration being greater than said second enhanced drain drift region dopant concentration;

said drain region having a drain dopant concentration greater than said third enhanced drain region dopant concentration;

said drain region contacting said third enhanced drain drift region.

28. The microwave transistor structure of claim 25, wherein said channel region further comprises:

a first enhanced drain drift region formed completely within said semiconductor material to a first depth level, said first enhanced drain drift region being of said second conductivity type, and having a first enhanced drain drift region dopant concentration;

a second enhanced drain drift region formed completely within said semiconductor material to a second depth level, said second enhanced drain drift region being of said second conductivity type, and having a second enhanced drain drift region dopant concentration, said second enhanced drain drift region contacting said first enhanced drain drift region;

said second enhanced drain drift region dopant concentration being greater than said first enhanced drain drift region dopant concentration;

a third enhanced drain drift region formed completely within said semiconductor material to a third depth level, said third enhanced drain drift region being of said second conductivity type, and having a third enhanced drain drift region dopant concentration, said third enhanced drain region contacting said second enhanced drain region;

said third enhanced drain drift region dopant concentration being greater than said second enhanced drain drift region dopant concentration; and

a fourth enhanced drain drift region formed completely within said semiconductor material to a fourth depth level, said fourth enhanced drain drift region being of said second conductivity type, and having a fourth enhanced drain drift region dopant concentration, said fourth enhanced drain drift region contacting said third enhanced drain drift region;

said fourth enhanced drain drift region dopant concentration being greater than said third enhanced drain drift region dopant concentration;

said drain region having a drain dopant concentration greater than said fourth enhanced drain region dopant concentration;

said drain region contacting said fourth enhanced drain drift region.

29. The microwave transistor structure of claim 25 further including:

a contact enhanced region formed in said silicon semiconductor material, said contact enhanced region being of said first conductivity type and having a contact enhanced region dopant concentration, said contact enhanced region dopant concentration being greater than said body region dopant concentration, said contact enhanced region being located within said body region.

30. The microwave transistor structure of claim 25, wherein said shield plate region further includes:

a shield plate region being connected to said source region.

31. The microwave transistor structure of claim 25, wherein said shield plate region further includes:

a shield plate region being connected to a backside of said structure.

32. The microwave transistor structure of claim 25, wherein said first conductivity type further comprises:

a P type conductivity type.

33. The microwave transistor structure of claim 25, wherein said conductive plug further comprises:

a metal plug.

34. The microwave transistor structure of claim 25, wherein said conductive plug further comprises:

a silicided plug.

35. The structure of claim 25, wherein said bonding layer further comprises:

a carbon layer.

36. The structure of claim 25, wherein said bonding layer further comprises:

a silicon layer.

37. The structure of claim 25, wherein said bonding layer further comprises:

a silicon dioxide layer.

38. The structure of claim 25, wherein said bonding layer further comprises:

a metal silicided layer selected from the group consisting of;

a tungsten silicided layer;

a titanium silicided layer; and

a cobalt silicided layer.

39. The microwave transistor structure of claim 25, wherein said silicon carbide substrate further comprises:

a substantially heavily doped silicon carbide substrate; and

wherein said substantially heavily doped silicon carbide substrate provides a thermal path and an electrical path for said microwave transistor.

40. The microwave transistor structure of claim 25, wherein said silicon carbide substrate further comprises:

a substantially lightly doped silicon carbide substrate having a substantially high resistivity; and

wherein said substantially lightly doped silicon carbide substrate having said substantially high resistivity provides a thermal path for said microwave transistor.

41. The microwave transistor structure of claim 25, wherein said conductive gate further comprises:

a highly doped polysilicon gate.

42. The microwave transistor structure of claim 25, wherein said conductive gate further comprises:

a sandwich gate further comprising a highly doped polysilicon bottom layer and a top layer selected from the group consisting of a tungsten silicided, a titanium silicided, a cobalt silicided, and a platinum silicided.

43. The microwave transistor structure of claim 25, wherein said conductive gate further comprises:

a metal gate.

44. The microwave transistor structure of claim 25, wherein said shield plate further comprises:

a metal shield plate.

45. The microwave transistor structure of claim 25, wherein said shield plate further comprises:

a polysilicon shield plate.

46. The microwave transistor structure of claim 25, wherein said shield plate further comprises:

a polysilicon/silicided shield plate sandwich.

47. The microwave transistor structure of claim 25, wherein said shield plate further comprises:

a polysilicon/metal shield plate sandwich.

48. The microwave transistor structure of claim 25, wherein said shield plate further comprises:

a shield plate extending above said top surface of said silicon semiconductor material to said shield plate height, wherein said shield plate height level is in the range of (4,000 Å

-8,000 Å

).

49. The microwave transistor structure of claim 29, wherein said conductive plug region further includes:

a conductive plug region formed in said contact enhanced region and said body region of said silicon semiconductor material, wherein said conductive plug region connects a top surface or a lateral surface of said contact enhanced region and connects a lateral surface of said body region to said top surface of said substrate.

50. The microwave transistor structure of claim 34, wherein said silicided plug is selected from the group consisting of a tungsten silicided plug, a titanium silicided plug, a cobalt silicided plug, and a platinum silicided plug.

51. The microwave transistor structure of claim 39, wherein said silicon carbide substrate further comprises:

a substantially heavily doped silicon carbide substrate having a resistivity lower than 0.1 Ω

cm.

52. The microwave transistor structure of claim 40, wherein said silicon carbide substrate further comprises:

a substantially lightly doped silicon carbide substrate having a resistivity higher than 10³ Ω

cm.

53. A microwave transistor structure comprising:

a silicon carbide substrate;

a first silicon dioxide layer overlaying said silicon carbide substrate;

a second silicon dioxide layer;

a silicon semiconductor material of a first conductivity type, said silicon semiconductor material having a first dopant concentration and a top surface;

said silicon semiconductor material bonded to said silicon carbide substrate via said first silicon dioxide layer and via said second silicon dioxide layer;

a conductive gate overlying and insulated from said top surface of said silicon semiconductor material;

a channel region formed completely within said silicon semiconductor material of said first conductivity type, said channel region being of a second conductivity type and having a channel region dopant concentration;

a drain region formed in said silicon semiconductor material, said drain region being of said second conductivity type and having a drain dopant concentration greater than said channel region dopant concentration;

said drain region contacting said channel region;

a body region formed in said silicon semiconductor material, said body region being of said first conductivity type and having a body region dopant concentration, said body region dopant concentration being equal or greater than said first dopant concentration, said body region having a first end underlying said conductive gate, any remaining portion of said silicon semiconductor material underlying said gate being of said first conductivity type;

a source region formed in said silicon semiconductor material, said source region being of said second conductivity type and having a source region dopant concentration, said source region being located within said body region;

a shield plate region formed on said top surface of said silicon semiconductor material over a portion of said channel region, said shield plate being adjacent and parallel to said drain region;

said shield plate being adjacent and parallel to said conductive gate region;

said shield plate extending above said top surface of said silicon semiconductor material to a shield plate height level, said shield plate being insulated from said top surface of said silicon semiconductor material; and

a conductive plug region formed in said body region of said silicon semiconductor material, wherein said conductive plug region connects a lateral surface of said body region to said top surface of said substrate.

54. The microwave transistor structure of claim 53, wherein said channel region further includes:

a first region formed completely within said silicon semiconductor material of said first conductivity type, said first region being of a second conductivity type to form a first enhanced drain drift region of said microwave transistor structure and having a first drain drift region dopant concentration; and

a second region formed in said silicon semiconductor material of said first conductivity type, said second region being of said second conductivity type to form a second enhanced drain drift region of said microwave transistor and having a second drain drift dopant concentration, said second enhanced drain drift region contacting said first enhanced drain drift region, said second enhanced drain drift region dopant concentration being greater than said first enhanced drain drift region dopant concentration;

said drain region having a drain dopant concentration greater than said second enhanced drain region dopant concentration;

said drain region contacting said second enhanced drain drift region.

55. The microwave transistor structure of claim 53, wherein said channel region further comprises:

a first enhanced drain drift region formed completely within said semiconductor material to a first depth level, said first enhanced drain drift region being of said second conductivity type, and having a first enhanced drain drift region dopant concentration;

a second enhanced drain drift region formed completely within said semiconductor material to a second depth level, said second enhanced drain drift region being of said second conductivity type, and having a second enhanced drain drift region dopant concentration, said second enhanced drain region contacting said first enhanced drain region;

said second enhanced drain drift region dopant concentration being greater than said first enhanced drain drift region dopant concentration; and

a third enhanced drain drift region formed completely within said semiconductor material to a third depth level, said third enhanced drain drift region being of said second conductivity type, and having a third enhanced drain drift region dopant concentration, said third enhanced drain drift region contacting said second enhanced drain drift region;

said third enhanced drain drift region dopant concentration being greater than said second enhanced drain drift region dopant concentration;

said drain region having a drain dopant concentration greater than said third enhanced drain region dopant concentration;

said drain region contacting said third enhanced drain drift region.

56. The microwave transistor structure of claim 53, wherein said channel region further comprises:

a first enhanced drain drift region formed completely within said semiconductor material to a first depth level, said first enhanced drain drift region being of said second conductivity type, and having a first enhanced drain drift region dopant concentration;

a second enhanced drain drift region formed completely within said semiconductor material to a second depth level, said second enhanced drain drift region being of said second conductivity type, and having a second enhanced drain drift region dopant concentration, said second enhanced drain drift region contacting said first enhanced drain drift region;

said second enhanced drain drift region dopant concentration being greater than said first enhanced drain drift region dopant concentration;

a third enhanced drain drift region formed completely within said semiconductor material to a third depth level, said third enhanced drain drift region being of said second conductivity type, and having a third enhanced drain drift region dopant concentration, said third enhanced drain region contacting said second enhanced drain region;

said third enhanced drain drift region dopant concentration being greater than said second enhanced drain drift region dopant concentration; and

a fourth enhanced drain drift region formed completely within said semiconductor material to a fourth depth level, said fourth enhanced drain drift region being of said second conductivity type, and having a fourth enhanced drain drift region dopant concentration, said fourth enhanced drain drift region contacting said third enhanced drain drift region;

said fourth enhanced drain drift region dopant concentration being greater than said third enhanced drain drift region dopant concentration;

said drain region having a drain dopant concentration greater than said fourth enhanced drain region dopant concentration;

said drain region contacting said fourth enhanced drain drift region.

57. The microwave transistor structure of claim 53 further including:

a contact enhanced region formed in said silicon semiconductor material, said contact enhanced region being of said first conductivity type and having a contact enhanced region dopant concentration, said contact enhanced region dopant concentration being greater than said body region dopant concentration, said contact enhanced region being located within said body region.

58. The microwave transistor structure of claim 53, wherein said shield plate region further includes:

a shield plate region being connected to said source region.

59. The microwave transistor structure of claim 53, wherein said shield plate region further includes:

a shield plate region being connected to a backside of said structure.

60. The microwave transistor structure of claim 53, wherein said first conductivity type further comprises:

a P type conductivity type.

61. The microwave transistor structure of claim 53, wherein said conductive plug further comprises:

a metal plug.

62. The microwave transistor structure of claim 53, wherein said conductive plug further comprises:

a silicided plug.

63. The microwave transistor structure of claim 53, wherein said silicon carbide substrate further comprises:

a substantially heavily doped silicon carbide substrate; and

wherein said substantially heavily doped silicon carbide substrate provides a thermal path and an electrical path for said microwave transistor.

64. The microwave transistor structure of claim 53, wherein said silicon carbide substrate further comprises:

a substantially lightly doped silicon carbide substrate having a substantially high resistivity; and

wherein said substantially lightly doped silicon carbide substrate having said substantially high resistivity provides a thermal path for said microwave transistor.

65. The microwave transistor structure of claim 53, wherein said conductive gate further comprises:

a highly doped polysilicon gate.

66. The microwave transistor structure of claim 53, wherein said conductive gate further comprises:

a sandwich gate further comprising a highly doped polysilicon bottom layer and a top layer selected from the group consisting of a tungsten silicided, a titanium silicided, a cobalt silicided, and a platinum silicided.

67. The microwave transistor structure of claim 53, wherein said conductive gate further comprises:

a metal gate.

68. The microwave transistor structure of claim 53, wherein said shield plate further comprises:

a metal shield plate.

69. The microwave transistor structure of claim 53, wherein said shield plate further comprises:

a polysilicon shield plate.

70. The microwave transistor structure of claim 53, wherein said shield plate further comprises:

a polysilicon/silicided shield plate sandwich.

71. The microwave transistor structure of claim 53, wherein said shield plate further comprises:

a polysilicon/metal shield plate sandwich.

72. The microwave transistor structure of claim 53, wherein said shield plate further comprises:

a shield plate extending above said top surface of said silicon semiconductor material to said shield plate height, wherein said shield plate height level is in the range of (4,000 Å

-8,000 Å

).

73. The microwave transistor structure of claim 57, wherein said conductive plug region further includes:

a conductive plug region formed in said contact enhanced region and said body region of said silicon semiconductor material, wherein said conductive plug region connects a top surface or a lateral surface of said contact enhanced region and connects a lateral surface of said body region to said top surface of said substrate.

74. The microwave transistor structure of claim 62, wherein said silicided plug is selected from the group consisting of a tungsten silicided plug, a titanium silicided plug, a cobalt silicided plug, and a platinum silicided plug.

75. The microwave transistor structure of claim 63, wherein said silicon carbide substrate further comprises:

a substantially heavily doped silicon carbide substrate having a resistivity lower than 0.1 Ω

cm.

76. The microwave transistor structure of claim 64, wherein said silicon carbide substrate further comprises:

a substantially lightly doped silicon carbide substrate having a resistivity higher than 10³ Ω

cm.