Semiconductor integrated circuit and fabrication method thereof

• US 6,316,787 B1
• Filed: 05/23/1997
• Issued: 11/13/2001
• Est. Priority Date: 06/04/1996
• Status: Expired due to Fees

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Ohtani, Hisashi
• Primary Examiner(s): Prenty, Mark V.
• Application Number:
  US08/862,895
• Time in Patent Office: 1,635 Days
• Field of Search: 257/350, 257/59, 257/72, 257/347, 257/351, 257/408
• US Class Current: 257/59
• CPC Class Codes: G02F 1/13454 Drivers integrated on the active matrix substrate G02F1/136277 takes precedence
• CPC Class Codes: H01L 27/1237 with a different composition, shape, layout or thickness of the gate insulator in different devices
• CPC Class Codes: H01L 27/124 with a particular composition, shape or layout of the wiring layers specially adapted to the circuit arrangement, e.g. scanning lines in LCD pixel circuits wiring structures per se H01L23/52
• CPC Class Codes: H01L 29/42384 for thin film field effect transistors, e.g. characterised by the thickness or the shape of the insulator or the dimensions, the shape or the lay-out of the conductor
• CPC Class Codes: H01L 29/4908 for thin film semiconductor, e.g. gate of TFT
• CPC Class Codes: H01L 29/78621 with LDD structure or an extension or an offset region or characterised by the doping profile

Abstract

A semiconductor integrated circuit having a high withstand voltage TFT and a TFT which is capable of operating at high speed in a circuit of thin film transistors (TFT) and methods for fabricating such circuit will be provided. A gate insulating film of the TFT required to operate at high speed (e.g., TFT used for a logic circuit) is relatively thinned less than a gate insulating film of the TFT which is required to have high withstand voltage (e.g., TFT used for switching high voltage signals).

Claims

1. A semiconductor device having a driving circuit and an active matrix circuit, said driving circuit comprising:

a logic circuit having at least a first thin film transistor formed over a substrate, said first thin film transistor having a first gate insulating film and a first gate electrode;

a buffer circuit having at least a second thin film transistor formed over said substrate, said second thin film transistor having a second gate insulating film and a second gate electrode; and

a high withstand voltage switching circuit having at least a third thin film transistor formed over said substrate, said third thin film transistor having a third gate insulating film and a third gate electrode,

wherein each width of said second and third gate electrodes is larger than the width of said first gate electrode,

wherein a thickness of said first gate insulating film is 80% or less of each thickness of said second and third gate insulating films.

9. A semiconductor device according to claim 1 wherein said second gate insulating film extends beyond the edges of said second gate electrode.

12. A semiconductor device according to claim 9 wherein at least a low concentration impurity region is located below said extending portion of said gate insulating film beyond said edge of said second gate electrode.

29. A semiconductor device according to claim 1 wherein said thickness of said second gate insulating film is less than 1500 Å

.

33. A semiconductor device according to claim 1 wherein said first and second thin film transistors have a first and a second semiconductor film comprising crystalline silicon respectively.

41. A semiconductor device according to claim 1 wherein said logic circuit is selected from the group consisting of a shift register, a CPU, a memory circuit and a decoder circuit.

48. An LCD using the semiconductor device according to claim 1.

56. A camera using the semiconductor device according to claim 1.

63. A portable personal computer using the semiconductor device according to claim 1.

71. A car navigation system using the semiconductor device according to claim 1.

79. A projector using the semiconductor device according to claim 1.

87. An electroluminescence display using the semiconductor device according to claim 1.

2. A semiconductor device having a driving circuit and an active matrix circuit, said driving circuit comprising:

a logic circuit having at least a first thin film transistor over a substrate;

a buffer circuit having at least a second thin film transistor over said substrate;

a high withstand voltage switching circuit having at least a third thin film transistor formed over said substrate;

said first thin film transistor having a first gate insulating film, a first gate electrode and a first channel region;

said second thin film transistor having a second gate insulating film, a second gate electrode and a second channel region; and

said third thin film transistor having a third gate insulating film, a third gate electrode and a third channel region,

wherein each width of said second and third gate electrodes is larger than the width of said first gate electrode,

wherein a thickness of said first gate insulating film is 80% or less of each thickness of said second and third gate insulating films, and

wherein a length of said first channel region is 80% or less of each length of said second and third channel regions.

10. A semiconductor device according to claim 2 wherein said second gate insulating film extends beyond edges of said second gate electrode.

13. A semiconductor device according to claim 10 wherein at least a low concentration impurity region is located below said extending portion of said gate insulating film beyond said edge of said second gate electrode.

30. A semiconductor device according to claim 2 wherein said thickness of said second gate insulating film is less than 1500 Å

.

34. A semiconductor device according to claim 2 wherein said first and second thin film transistors have a first and a second semiconductor film comprising crystalline silicon respectively.

42. A semiconductor device according to claim 2 wherein said logic circuit is selected from the group consisting of a shift register, a CPU, a memory circuit and a decoder circuit.

49. An LCD using the semiconductor device according to claim 2.

57. A camera using the semiconductor device according to claim 2.

64. A portable personal computer using semiconductor device according to claim 2.

72. A car navigation system using the semiconductor device according to claim 2.

80. A projector using the semiconductor device according to claim 2.

88. An electroluminescence display using the semiconductor device according to claim 2.

3. A semiconductor device, having a driving circuit and an active matrix circuit, said driving circuit compromising:

a logic circuit having a least a first thin film transistor formed over a substrate, said first thin film transistor having a first gate insulating film and a first gate electrode; and

a high withstand voltage switching circuit having at least a second thin film transistor formed over said substrate, said second thin film transistor having a second gate insulating film and a second gate electrode,

wherein a thickness of said first gate insulating film is 80% or less of a thickness or said second gate insulating film.

31. A semiconductor device according to claim 3 wherein said thickness of said second gate insulating film is less than 1500 Å

.

35. A semiconductor device according to claim 3 wherein said first and second thin film transistors have a first and a second semiconductor film comprising crystalline silicon respectively.

50. An LCD using the semiconductor device according to claim 3.

58. A camera using the semiconductor device according to claim 3.

65. A portable personal computer using the semiconductor device according to claim 3.

73. A car navigation system using the semiconductor device according to claim 3.

81. A projector using the semiconductor device according to claim 3.

89. An electroluminescence display using the semiconductor device according to claim 3.

4. A semiconductor device, said semiconductor device having a driving circuit and an active matrix circuit, said driving circuit comprising:

a logic circuit having at least a first thin film transistor formed over a substrate, said first thin film transistor having a first gate insulating film and a first channel region; and

a high withstand voltage switching circuit having at least a second thin film transistor formed over said substrate, said second thin film transistor having a second gate insulating film and a second channel region,

wherein a first thickness of said first gate insulating film is 80% or less of a second thickness of said second gate insulating film, and

wherein a first length of said first channel region is 80% or less of a second length of said second channel region.

11. A semiconductor device according to claim 4 wherein said second gate insulating film extends beyond edges of said second gate electrode.

14. A semiconductor device according to claim 11 wherein at least a low concentration impurity region is located below said extending portion of said gate insulating film beyond said second gate electrode.

32. A semiconductor device according to claim 4 wherein said thickness of said second gate insulating film is less than 1500 Å

.

36. A semiconductor device according to claim 4 wherein said first and second thin film transistors have a first and a second semiconductor film comprising crystalline silicon respectively.

43. A semiconductor device according to claim 4 wherein said logic circuit is selected from the group consisting of a shift register, a CPU, a memory circuit and a decoder circuit.

51. An LCD using the semiconductor device according to claim 4.

59. A camera using the semiconductor device according to claim 4.

66. A portable personal computer using the semiconductor device according to claim 4.

74. A car navigation system using the semiconductor device according to claim 4.

82. A projector using the semiconductor device according to claim 4.

90. An electroluminescence display using the semiconductor device according to claim 4.

5. A semiconductor device having a driving circuit and an active matrix circuit, said driving circuit comprising:

a logic circuit having at least a first thin film transistor formed over a substrate, said first thin film transistor having a first gate insulating film and a first gate electrode; and

a high withstand voltage switching circuit having at least a second thin film transistor formed over said substrate, said second thin film transistor having a second gate insulating film and a second gate electrode,

wherein a thickness of said first gate insulating film is 80% or less of a thickness of said second gate insulating film,

wherein a width of said second gate electrode is larger than the width of said first gate electrode.

16. A semiconductor device according to claim 5 wherein said thickness of said second gate insulating film is less than 1500 Å

.

17. A semiconductor device according to claim 5 wherein said second gate insulating film extends beyond edges of said second gate electrode.

18. A semiconductor device according to claim 17 wherein at least a low concentration impurity region is located below said extending portion of said second gate insulating film beyond said edge of said second gate electrode.

37. A semiconductor device according to claim 5 wherein said first and second thin film transistors have a first and a second semiconductor film comprising crystalline silicon respectively.

44. A semiconductor device according to claim 5 wherein said logic circuit is selected from the group consisting of a shift register, a CPU, a memory circuit and a decoder circuit.

52. An LCD using the semiconductor device according to claim 5.

60. A camera using the semiconductor device according to claim 5.

67. A portable personal computer using the semiconductor device according to claim 5.

75. A car navigation system using the semiconductor device according to claim 5.

83. A projector using the semiconductor device according to claim 5.

91. An electroluminescence display using the semiconductor device according to claim 5.

6. A semiconductor device having a driving circuit and an active matrix circuit, said driving circuit comprising:

a logic circuit having at least a first thin film transistor formed over a substrate, said first thin film transistor having a first gate insulating film, a first gate electrode and a first channel region; and

a high withstand voltage circuit having at least a second thin film transistor formed over said substrate, said second thin film transistor having a second gate insulating film, a second gate electrode, and a second channel region,

wherein a first thickness of said first gate insulating film is 80% or less of a second thickness of said second gate insulating film,

wherein a first length of said first channel region is 80% or less of a second length of said second channel region,

wherein a width of said second gate electrode is larger than the width of said first gate electrode.

19. A semiconductor device according to claim 6 wherein said thickness of said second gate insulating film is less than 1500 Å

.

20. A semiconductor device according to claim 6 wherein said second gate insulating film extends beyond edges of said second gate electrode.

21. A semiconductor device according to claim 6 wherein at least a low concentration impurity region is located below said extending portion of said second gate insulating film beyond said edge of said second gate electrode.

38. A semiconductor device according to claim 6 wherein said first and second thin film transistors have a first and a second semiconductor film comprising crystalline silicon respectively.

45. A semiconductor device according to claim 6 wherein said logic circuit is selected from the group consisting of a shift register, a CPU, a memory circuit and a decoder circuit.

53. An LCD using the semiconductor device according to claim 6.

61. A camera using the semiconductor device according to claim 6.

68. A portable personal computer using the semiconductor device according to claim 6.

76. A car navigation system using the semiconductor device according to claim 6.

84. A projector using the semiconductor device according to claim 6.

92. An electroluminescence display using the semiconductor device according to claim 6.

7. A semiconductor device having a driving circuit and an active matrix circuit, said driving circuit comprising:

a logic circuit having at least a first thin film transistor formed over a substrate, said first thin film transistor having a first gate insulating film and a first gate electrode;

a buffer circuit having at least a second thin film transistor formed over said substrate, said second thin film transistor having a second gate insulating film and a second gate electrode; and

a high withstand voltage switching circuit having at least a third thin film transistor formed over said substrate, said third thin film transistor having a third gate insulating film and a third gate electrode,

wherein a thickness of said first gate insulating film is 80% or less of each thickness of said second and third gate insulating films.

15. A camera using the semiconductor device according to claim 7.

22. A semiconductor device according to claim 7 wherein said thickness of said second gate insulating film is less than 1500 Å

.

23. A semiconductor device according to claim 7 wherein said second gate insulating film extends beyond edges of said second gate electrode.

24. A semiconductor device according to claim 23 wherein at least a low concentration impurity region is located below said extending portion of said second gate insulating film beyond said edge of said second gate electrode.

39. A semiconductor device according to claim 7 wherein said first and second thin film transistors have a first and a second semiconductor film comprising crystalline silicon respectively.

46. A semiconductor device according to claim 7 wherein said logic circuit is selected from the group consisting of a shift register, a CPU, a memory circuit and a decoder circuit.

54. An LCD using the semiconductor device according to claim 7.

69. A portable personal computer using the semiconductor device according to claim 7.

77. A car navigation system using the semiconductor device according to claim 7.

85. A projector using the semiconductor device according to claim 7.

93. An electroluminescence display using the semiconductor device according to claim 7.

8. A semiconductor device having a driving circuit and an active matrix circuit, said driving circuit comprising:

a logic circuit having at least a first thin film transistor formed over a substrate, said first thin film transistor having a first gate insulating film, a first gate electrode and a first channel region;

a buffer circuit having at least a second thin film transistor formed over said substrate, said second thin film transistor having a second gate insulating film, a second gate electrode and a second channel region; and

a high withstand voltage switching circuit having at least a third thin film transistor formed over said substrate, said third thin film transistor having a third gate insulating film and a third channel region,

wherein a thickness of said first gate insulating film is 80% or less of each thickness of said second and third gate insulating films,

wherein a length of said first channel region is 80% or less of each length of said second and third channel regions.

25. A semiconductor device according to claim 8 wherein a width of said second gate electrode is larger than the width of said first gate electrode.

26. A semiconductor device according to claim 8 wherein said thickness of said second gate insulating film is less than 1500 Å

.

27. A semiconductor device according to claim 8 wherein said second gate insulating film extends beyond edges of said second gate electrode.

28. A semiconductor device according to claim 27 wherein at least a low concentration impurity region is located below said extending portion of said second gate insulating film beyond said edge of said second gate electrode.

40. A semiconductor device according to claim 8 wherein said first and second thin film transistors have a first and a second semiconductor film comprising crystalline silicon respectively.

47. A semiconductor device according to claim 8 wherein said logic circuit is selected from the group consisting of a shift register, a CPU, a memory circuit and a decoder circuit.

55. An LCD using the semiconductor integrated circuit according to claim 8.

62. A camera a using the semiconductor device according to claim 8.

70. A portable personal computer using the semiconductor device according to claim 8.

78. A car navigation system using the semiconductor device according to claim 8.

86. A projector using the semiconductor device according to claim 8.

94. An electroluminescence display using the semiconductor device according to claim 8.