Semiconductor integrated circuit and method for forming the same

• US 6,433,361 B1
• Filed: 02/05/1997
• Issued: 08/13/2002
• Est. Priority Date: 04/29/1994
• Status: Expired due to Term

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Suzawa, Hideomi, Zhang, Hongyong, Takenouchi, Akira
• Primary Examiner(s): CRANE, SARA W
• Application Number:
  US08/999,703
• Time in Patent Office: 2,015 Days
• Field of Search: 257/57, 257/59, 257/619, 257/72, 257/350, 257/351, 257/347, 257/66, 257/69
• US Class Current: 257/59
• CPC Class Codes: H01L 27/1214 comprising a plurality of TFTs formed on a non-semiconducting substrate, e.g. driving circuits for AMLCDs

Abstract

In forming a thin film transistor (TFT), a semiconductor region is formed on a glass substrate and then a gate electrode is formed on the semiconductor region through an gate insulating film. After the gate electrode and a gate electrode arrangement extended from the gate electrode is anodized, insulators each having approximately rectangular shape are formed on side surfaces of the gate electrode and the gate electrode arrangement. An interlayer insulator is formed on a whole surface, and then the second layer arrangement is formed on the interlayer insulator. In an overlap portion in which the second layer arrangement overlaps the gate electrode and the gate electrode arrangement, since the insulators is formed, a slope is small.

Claims

1. A semiconductor device comprising:

an n-channel type thin film transistor comprising a first semiconductor film formed over a substrate having an insulating surface, a pair of source and drain regions of an n-type conductivity in said first semiconductor film, a channel forming region in said first semiconductor film, at least one lightly doped region with a dose amount of 5×

10¹⁴ atoms/cm² or less formed between said channel forming region and at least one of said source and drain regions, a first gate insulating film adjacent to said channel forming region and a first gate electrode adjacent to said channel forming region with said first gate insulating film interposed therebetween; and

a p-channel type thin film transistor connected to said n-channel type thin film transistor, said p-channel type thin film transistor comprising a second semiconductor film formed over said substrate, a pair of source and drain regions of a p-type conductivity in said second semiconductor film, a channel forming region between said source and drain regions in said second semiconductor film, a second gate insulating film adjacent to said channel forming region and a second gate electrode adjacent to said channel forming region with said second gate insulating film interposed therebetween,

wherein said p-channel type thin film transistor has no lightly doped region in said second semiconductor film.

2. A semiconductor device according to claim 1 wherein the gate electrode is located over the channel forming region in each of the n-channel type thin film transistor and the p-channel type thin film transistor.

13. A semiconductor device according to claim 1 wherein said p-channel type thin film transistor is complementarily connected to said n-channel type thin film transistor.

45. A semiconductor device according to claim 1 further comprising an anodic oxide film on said gate electrode;

and a substantially triangular insulator adjacent to a side surface of said gate electrode, wherein said lightly doped region is provided under said substantially triangular insulator.

3. A semiconductor device comprising:

an n-channel type thin film transistor comprising a first semiconductor film formed over a substrate having an insulating surface, a pair of source and drain regions of an n-type conductivity in said first semiconductor film, a channel forming region in said first semiconductor film, at least one lightly doped region formed between said channel forming region and at least one of said source and drain regions, a first gate insulating film adjacent to said channel forming region and a first gate electrode adjacent to said channel forming region with said first gate insulating film interposed therebetween; and

a p-channel type thin film transistor connected to said n-channel type thin film transistor, said p-channel type thin film transistor comprising a second semiconductor film formed over said substrate, a pair of source and drain regions of a p-type conductivity in said second semiconductor film, a channel forming region in said second semiconductor film between said source and drain regions, a second gate insulating film adjacent to said channel forming region and a second gate electrode adjacent to said channel forming region with said second gate insulating film interposed therebetween,

wherein said p-channel type thin film transistor has no lightly doped region in said second semiconductor film, and said source and said drain regions are doped with both phosphorus and boron.

4. A semiconductor device according to claim 3 wherein the gate electrode is located over the channel forming region in each of the n-channel type thin film transistor and the p-channel type thin film transistor.

14. A semiconductor device according to claim 3 wherein said p-channel type thin film transistor is complementarily connected to said n-channel type thin film transistor.

46. A semiconductor device according to claim 3 further comprising an anodic oxide film on said gate electrode;

and a substantially triangular insulator adjacent to a side surface of said gate electrode, wherein said lightly doped region is provided under said substantially triangular insulator.

5. A semiconductor device comprising:

a substrate having an insulating surface;

a first semiconductor film and a second semiconductor film formed over said substrate wherein said first semiconductor film constitutes an n-channel type thin film transistor and said second semiconductor film constitutes a p-channel type thin film transistor;

a gate insulating film formed on said first and second semiconductor films;

a pair of first impurity regions formed in said first semiconductor film, said first impurity regions having an n-type conductivity;

a first channel forming region formed in said first semiconductor film between said first impurity regions;

at least one lightly doped region disposed between said first channel forming region and at least one of said first impurity regions wherein said lightly doped region is doped with an n-type impurity at a lower concentration than said first impurity regions;

a pair of second impurity regions formed in said second semiconductor film, said impurity regions having a p-type conductivity;

a second channel forming region in said second semiconductor film between said second impurity regions wherein no lightly doped region is disposed in said second impurity regions, said second impurity regions containing both phosphorus and boron;

a first gate electrode and a second gate electrode formed over the first and second channel forming regions, respectively, with said gate insulating film interposed therebetween; and

an insulating film comprising silicon nitride formed over said gate insulating film and said first and second gate electrodes,

wherein said gate insulating film and said insulating film cover said first and second semiconductor films except for contact holes opened therein.

47. A semiconductor device according to claim 5 further comprising an anodic oxide film on said gate electrode;

and a substantially triangular insulator adjacent to a side surface of said gate electrode, wherein said lightly doped region is provided under said substantially triangular insulator.

6. A semiconductor device comprising:

a substrate having an insulating surface;

a first semiconductor film and a second semiconductor film formed over said substrate wherein said first semiconductor film constitutes an n-channel type thin film transistor and said second semiconductor film constitutes a p-channel type thin film transistor;

a gate insulating film formed on said first and second semiconductor films;

a pair of first impurity regions formed in said first semiconductor film, said first impurity regions having an n-type conductivity;

a first channel forming region formed in said first semiconductor film between said first impurity regions;

at least one lightly doped region disposed between said first channel forming region and at least one of said first impurity regions wherein said lightly doped region is doped with an n-type impurity at a lower concentration than said first impurity regions;

a pair of second impurity regions formed in said second semiconductor film, said impurity regions having a p-type conductivity;

a second channel forming region in said second semiconductor film between said second impurity regions wherein no lightly doped region is disposed in said second impurity regions;

a pair of third impurity regions formed in said second semiconductor film wherein said third impurity regions contain both of phosphorus and boron and are contiguous to said second impurity regions;

a first gate electrode and a second gate electrode formed over the first and second channel forming regions, respectively, with said gate insulating film interposed therebetween; and

an insulating film comprising silicon nitride formed over said gate insulating film and said first and second gate electrodes,

wherein said gate insulating film and said insulating film cover said first and second semiconductor films except for contact holes opened therein.

48. A semiconductor device according to claim 6 further comprising an anodic oxide film on said gate electrode;

and a substantially triangular insulator adjacent to a side surface of said gate electrode, wherein said lightly doped region is provided under said substantially triangular insulator.

7. A semiconductor device having an active matrix circuit comprising a plurality of switching elements formed over a substrate for switching pixels;

and a driver circuit for driving said active matrix circuit, said driver circuit comprising;

an n-channel type thin film transistor comprising a first semiconductor film formed over said substrate, a pair of source and drain regions in said first semiconductor film, a channel forming region formed between said source and drain regions, at least one lightly doped region with a dose amount of 5×

10¹⁴ atoms/cm² or less formed between said channel forming region and at least one of said source and drain regions, a first gate insulating film adjacent to said channel forming region and a first gate electrode adjacent to said channel forming region with said first gate insulating film interposed therebetween; and

a p-channel type thin film transistor connected to said n-channel type thin film transistor, said p-channel type thin film transistor comprising a second semiconductor film formed over said second semiconductor film, a channel forming region between a source and a drain regions in said second semiconductor film, a second gate insulating film adjacent to said channel forming region and a second gate electrode adjacent to said channel forming region with said second gate insulating film interposed therebetween,

wherein said p-channel type thin film transistor has no lightly doped region in said second semiconductor film.

8. A semiconductor device according to claim 7 wherein the gate electrode is located over the channel forming region in each of the n-channel type thin film transistor and the p-channel type thin film transistor.

15. A semiconductor device according to claim 7 wherein said p-channel type thin film transistor is complementarily connected to said n-channel type thin film transistor.

49. A semiconductor device according to claim 7 further comprising an anodic oxide film on said gate electrode;

and a substantially triangular insulator adjacent to a side surface of said gate electrode, wherein said lightly doped region is provided under said substantially triangular insulator.

9. A semiconductor device having an active matrix circuit comprising a plurality of switching elements formed over a substrate for switching pixels;

and a driver circuit for driving said active matrix circuit, said driver circuit comprising;

an n-channel type thin film transistor comprising a first semiconductor film formed over said substrate, a pair of source and drain regions of an n-type conductivity in said first semiconductor film, a channel forming region in said first semiconductor film, at least one lightly doped region formed between said channel forming region and at least one of said source and drain regions, a first gate insulating film adjacent to said channel forming region and a first gate electrode adjacent to said channel forming region with said first gate insulating film interposed therebetween; and

a p-channel type thin film transistor connected to said n-channel type thin film transistor, said p-channel type thin film transistor comprising a second semiconductor film formed over said substrate, a pair of source and drain regions of a p-type conductivity in said second semiconductor film, a channel forming region in said second semiconductor film between said source and drain regions, a second gate insulating film adjacent to said channel forming region and a second gate electrode adjacent to said channel forming region with said second gate insulating film interposed therebetween,

wherein said p-channel type thin film transistor has no lightly doped region in said second semiconductor film, and said source and said drain regions are doped with both phosphorus and boron.

10. A semiconductor device according to claim 9 wherein the gate electrode is located over the channel forming region in each of the n-channel type thin film transistor and the p-channel type thin film transistor.

16. A semiconductor device according to claim 9 wherein said p-channel type thin film transistor is complementarily connected to said n-channel type thin film transistor.

50. A semiconductor device according to claim 9 further comprising an anodic oxide film on said gate electrode;

and a substantially triangular insulator adjacent to a side surface of said gate electrode, wherein said lightly doped region is provided under said substantially triangular insulator.

11. A semiconductor device having an active matrix circuit comprising a plurality of switching elements formed on an insulating surface of a substrate for switching pixels and a driver circuit for driving said active matrix circuit, said driver circuit comprising:

a first semiconductor film and a second semiconductor film formed over said substrate wherein said first semiconductor film constitutes an n-channel type thin film transistor and said second semiconductor film constitutes a p-channel type thin film transistor;

a gate insulating film formed on said first and second semiconductor films;

a pair of first impurity regions formed in said first semiconductor film, said first impurity regions having an n-type conductivity;

a first channel forming region formed in said first semiconductor film between said first impurity regions;

at least one lightly doped region disposed between said first channel forming region and at least one of said first impurity regions wherein said lightly doped region is doped with an n-type impurity at a lower concentration than said first impurity regions;

a pair of second impurity regions formed in said second semiconductor film, said impurity regions having a p-type conductivity;

a second channel forming region in said second semiconductor film between said second impurity regions wherein no lightly doped region is disposed in said second impurity regions, said second impurity regions containing both phosphorus and boron;

a first gate electrode and a second gate electrode formed over the first and second channel forming regions, respectively, with said gate insulating film interposed therebetween; and

an insulating film comprising silicon nitride formed over said gate film and said first and second gate electrodes,

wherein said gate insulating film and said insulating film cover said first and second semiconductor films except for contact holes opened therein.

51. A semiconductor device according to claim 11 further comprising an anodic oxide film on said gate electrode;

and a substantially triangular insulator adjacent to a side surface of said gate electrode, wherein said lightly doped region is provided under said substantially triangular insulator.

12. A semiconductor device having an active matrix circuit comprising a plurality of switching elements formed on an insulating surface of a substrate for switching pixels and a driver circuit for driving said active matrix circuit, said driver circuit comprising:

a substrate having an insulating surface;

a first semiconductor film and a second semiconductor film formed over said substrate wherein said first semiconductor film constitutes an n-channel type thin film transistor and said second semiconductor film constitutes a p-channel type thin film transistor;

a gate insulating film formed on said first and second semiconductor films;

a pair of first impurity regions formed in said first semiconductor film, said first impurity regions having an n-type conductivity;

a first channel forming region formed in said first semiconductor between said first impurity regions;

at least one lightly doped region disposed between said first channel forming region and at least one of said first impurity regions wherein said lightly doped region is doped with an n-type impurity at a lower concentration than said first impurity region;

a pair of second impurity regions formed in said second semiconductor film, said impurity regions having a p-type conductivity;

a second channel forming region in said second semiconductor film between said second impurity regions wherein no lightly doped region is disposed in said second impurity regions;

a pair of third impurity regions formed in said second semiconductor film wherein said third impurity regions contain both of phosphorus and boron and are contiguous to said second impurity regions;

a first gate electrode and a second gate electrode formed over the first and second channel forming regions, respectively, with said gate insulating film interposed therebetween; and

an insulating film comprising silicon nitride formed over said gate insulating film and said first and second gate electrodes,

wherein said gate insulating film and said interlayer insulating film cover said first and second semiconductor films except for contact holes opened therein.

52. A semiconductor device according to claim 12 further comprising an anodic oxide film on said gate electrode;

and a substantially triangular insulator adjacent to a side surface of said gate electrode, wherein said lightly doped region is provided under said substantially triangular insulator.

17. A semiconductor device comprising an n-channel type thin film transistor and a p-channel type thin film transistor connected with said n-channel type thin film transistor, each comprising:

a semiconductor film formed over a substrate having an insulating surface;

a pair of source and drain regions in said semiconductor film;

a channel region in said semiconductor film; and

a gate insulating film adjacent to said channel region and a gate electrode adjacent to said channel region with said gate insulating film interposed therebetween,

wherein said n-channel type thin film transistor has at least one lightly doped region with a dose amount of 5×

10¹⁴ atoms/cm² or less between said channel region and at least one of said source and drain regions, and

wherein said p-channel type thin film transistor has no lightly doped region in said semiconductor film.

18. A semiconductor device according to claim 17 wherein the gate electrode is located over the channel region in each of the n-channel type thin film transistor and the p-channel type thin film transistor.

19. A semiconductor device according to claim 17 wherein said p-channel type thin film transistor is complementarily connected to said n-channel type thin film transistor.

53. A semiconductor device according to claim 17 further comprising an anodic oxide film on said gate electrode;

and a substantially triangular insulator adjacent to a side surface of said gate electrode, wherein said lightly doped region is provided under said substantially triangular insulator.

20. A semiconductor device comprising an n-channel type thin film transistor and a p-channel type thin film transistor, each comprising:

a semiconductor film formed over a substrate having an insulating surface;

a pair of source and drain regions in said semiconductor film;

a channel region in said semiconductor film; and

a gate insulating film adjacent to said channel region and a gate electrode adjacent to said channel region with said gate insulating film interposed therebetween,

wherein said n-channel type thin film transistor has at least one lightly doped region between said channel region and at least one of said source and drain regions, and

wherein said p-channel type thin film transistor has no lightly doped region in said semiconductor film, and said source and drain regions are doped with both phosphorus and boron.

21. A semiconductor device according to claim 20 wherein the gate electrode is located over the channel forming region in each of the n-channel type thin film transistor and the p-channel type thin film transistor.

22. A semiconductor device according to claim 20 wherein said p-channel type thin film transistor is complementarily connected to said n-channel type thin film transistor.

54. A semiconductor device according to claim 20 further comprising an anodic oxide film on said gate electrode;

and a substantially triangular insulator adjacent to a side surface of said gate electrode, wherein said lightly doped region is provided under said substantially triangular insulator.

23. A semiconductor device comprising an n-channel type thin film transistor and a p-channel type thin film transistor, each comprising:

a semiconductor film formed over a substrate having an insulating surface;

a gate insulating film formed on said semiconductor film;

a pair of impurity regions formed in said semiconductor film;

a channel region formed in said semiconductor film between said pair of impurity regions;

a gate electrode formed over the channel region with said gate insulating film interposed therebetween; and

an interlayer insulating film comprising silicon nitride formed over said gate insulating film and said gate electrode,

wherein said n-channel type thin film transistor has at least one lightly doped region disposed between said channel region and at least one of said pair of impurity regions and said p-channel type thin film transistor has no lightly doped region in said pair of impurity regions, and said pair of impurity regions of said p-channel type thin film transistor containing both phosphorus and boron, and

wherein said gate insulating film and said interlayer insulating film cover said semiconductor film except for contact holes opened therein.

55. A semiconductor device according to claim 23 further comprising an anodic oxide film on said gate electrode;

and a substantially triangular insulator adjacent to a side surface of said gate electrode, wherein said lightly doped region is provided under said substantially triangular insulator.

24. A semiconductor device comprising an n-channel type thin film transistor and a p-channel type thin film transistor, each comprising:

a semiconductor film formed over a substrate having an insulating surface;

a gate insulating film formed on said semiconductor film;

a pair of impurity regions formed in said semiconductor film;

a channel region formed in said semiconductor film between said pair of impurity regions;

a gate electrode formed over the channel region with said gate insulating film interposed therebetween; and

an insulating film formed over said gate insulating film and said first and second gate electrodes,

wherein said n-channel type thin film transistor has at least one lightly doped region disposed between said channel region and at least one of said pair of impurity region, and said p-channel type thin film transistor has no lightly doped region in said pair of impurity regions, and said pair of impurity regions of said p-channel type thin film transistor containing both phosphorus and boron, and

wherein said gate insulating film and said interlayer insulating film cover said semiconductor film except for contact holes opened therein.

56. A semiconductor device according to claim 24 further comprising an anodic oxide film on said gate electrode;

and a substantially triangular insulator adjacent to a side surface of said gate electrode, wherein said lightly doped region is provided under said substantially triangular insulator.

65. A semiconductor device according to claim 24 wherein said insulating film comprises silicon nitride.

25. A semiconductor device having an active matrix circuit comprising a plurality of switching elements formed over a substrate for switching pixels;

and a driver circuit for driving said active matrix circuit, said driver circuit comprising an n-channel type thin film transistor and a p-channel type thin film transistor connected with said n-channel type thin film transistor, each comprising;

a semiconductor film formed over a substrate having an insulating surface;

a pair of source and drain regions in said semiconductor film;

a channel region in said semiconductor film; and

a gate insulating film adjacent to said channel region and a gate electrode adjacent to said channel region with said gate insulating film interposed therebetween,

wherein said n-channel type thin film transistor has at least one lightly doped region with a dose amount of 5×

10¹⁴ atoms/cm² or less between said channel region and at least one of said source and drain regions, and

wherein said p-channel type thin film transistor has no lightly doped region in said semiconductor film.

26. A semiconductor device according to claim 25 wherein the gate electrode is located over the channel forming region in each of the n-channel type thin film transistor and the p-channel type thin film transistor.

27. A semiconductor device according to claim 25 wherein said p-channel type thin film transistor is complementarily connected to said n-channel type thin film transistor.

57. A semiconductor device according to claim 25 further comprising an anodic oxide film on said gate electrode;

and a substantially triangular insulator adjacent to a side surface of said gate electrode, wherein said lightly doped region is provided under said substantially triangular insulator.

28. A semiconductor device having an active matrix circuit comprising a plurality of switching elements formed over a substrate for switching pixels;

and a driver circuit for driving said active matrix circuit, said driver circuit comprising an n-channel type thin film transistor and a p-channel type thin film transistor, each comprising;

a semiconductor film formed over a substrate having an insulating surface;

a pair of source and drain regions in said semiconductor film;

a channel region in said semiconductor film; and

a gate insulating film adjacent to said channel region and a gate electrode adjacent to said channel region with said gate insulating film interposed therebetween,

wherein said n-channel type thin film transistor has at least one lightly doped region between said channel region and at least one of said source and drain regions, and

wherein said p-channel type thin film transistor has no lightly doped region in said semiconductor film, and said source and drain regions are doped with both phosphorus and boron.

29. A semiconductor device according to claim 28 wherein the gate electrode is located over the channel forming region in each of the n-channel type thin film transistor and the p-channel type thin film transistor.

30. A semiconductor device according to claim 28 wherein said p-channel type thin film transistor is complementarily connected to said n-channel type thin film transistor.

58. A semiconductor device according to claim 28 further comprising an anodic oxide film on said gate electrode;

and a substantially triangular insulator adjacent to a side surface of said gate electrode, wherein said lightly doped region is provided under said substantially triangular insulator.

31. A semiconductor device having an active matrix circuit comprising a plurality of switching elements formed over a substrate for switching pixels;

and a peripheral circuit for driving said active matrix circuit, said peripheral circuit comprising an n-channel type thin film transistor and a p-channel type thin film transistor, each comprising;

a semiconductor film formed over a substrate having an insulating surface;

a gate insulating film formed on said semiconductor films;

a pair of impurity regions formed in said semiconductor film;

channel region formed in said semiconductor film between said pair of impurity regions;

a gate electrode formed over the channel region with said gate insulating film interposed therebetween; and

an insulating film comprising silicon nitride formed over said gate insulating film and said gate electrode,

wherein said n-channel type thin film transistor has at least one lightly doped region disposed between said channel region and at least one of said pair of impurity region and said p-channel type thin film transistor has no lightly doped region in said pair of impurity regions of said p-channel type thin film transistor containing both phosphorus and boron, and

wherein said gate insulating film and said interlayer insulating film cover said semiconductor film except for contact holes opened therein.

59. A semiconductor device according to claim 31 further comprising an anodic oxide film on said gate electrode;

and a substantially triangular insulator adjacent to a side surface of said gate electrode, wherein said lightly doped region is provided under said substantially triangular insulator.

32. A semiconductor device having an active matrix circuit comprising a plurality of switching elements formed over a substrate for switching pixels;

and a peripheral circuit for driving said active matrix circuit, said peripheral circuit comprising an n-channel type thin film transistor and a p-channel type thin film transistor, each comprising;

a semiconductor film formed over a substrate having an insulating surface;

a gate insulating film formed on said semiconductor film;

a pair of impurity regions formed in said semiconductor film;

a channel region formed in said semiconductor film between said pair of impurity regions;

a gate electrode formed over the channel region with said gate insulating film interposed therebetween; and

an interlayer insulating film formed over said gate insulating film and said gate electrode,

wherein said n-channel type thin film transistor has at least one lightly doped region disposed between said channel region and at least one of said pair of impurity regions, and said p-channel type thin film transistor has no lightly doped region in said pair of impurity regions, and said pair of impurity regions of said p-channel type thin film transistor containing both phosphorus and boron, and

wherein said gate insulating film and said interlayer insulating film cover said semiconductor film except for contact holes opened therein.

60. A semiconductor device according to claim 32 further comprising an anodic oxide film on said gate electrode;

and a substantially triangular insulator adjacent to a side surface of said gate electrode, wherein said lightly doped region is provided under said substantially triangular insulator.

66. A semiconductor device according to claim 32 wherein said insulating film comprises silicon nitride.

33. An input port comprising an n-channel type thin film transistor and a p-channel type thin film transistor, each comprising:

a semiconductor film formed over a substrate having an insulating surface;

a pair of source and drain regions in said semiconductor film;

a channel region in said semiconductor film; and

a gate insulating film adjacent to said channel region and a gate electrode adjacent to said channel region with said gate insulating film interposed therebetween,

wherein said n-channel type thin film transistor has at least one lightly doped region between said channel region and at least one of said source and drain regions,

wherein said p-channel type thin film transistor has no lightly doped region in said semiconductor film, and

wherein said source and drain regions of said p-channel type thin film transistor contain both phosphorus and boron.

34. An input port according to claim 33 wherein the gate electrode is located over the channel region in each of the n-channel type thin film transistor and the p-channel type thin film transistor.

35. An input port according to claim 33 wherein said p-channel type thin film transistor is complementarily connected to said n-channel type thin film transistor.

61. An input port according to claim 33 further comprising an anodic oxide film on said gate electrode;

and a substantially triangular insulator adjacent to a side surface of said gate electrode, wherein said lightly doped region is provided under said substantially triangular insulator.

36. A central processing unit comprising an n-channel type thin film transistor and a p-channel type thin film transistor, each comprising:

a semiconductor film formed over a substrate having an insulating surface;

a pair of source and drain regions in said semiconductor film;

a channel region in said semiconductor film; and

a gate insulating film adjacent to said channel region and a gate electrode adjacent to said channel region with said gate insulating film interposed therebetween,

wherein said n-channel type thin film transistor has at least one lightly doped region between said channel region and at least one of said source and drain regions,

wherein said p-channel type thin film transistor has no lightly doped region in said semiconductor film, and

wherein said source and drain regions of said p-channel type thin film transistor contain both phosphorus and boron.

37. A central processing unit according to claim 36 wherein the gate electrode is located over the channel region in each of the n-channel type thin film transistor and the p-channel type thin film transistor.

38. A central processing unit according to claim 36 wherein said p-channel type thin film transistor is complementarily connected to said n-channel type thin film transistor.

62. A central processing unit according to claim 36 further comprising an anodic oxide film on said gate electrode;

and a substantially triangular insulator adjacent to a side surface of said gate electrode, wherein said lightly doped region is provided under said substantially triangular insulator.

39. A memory circuit comprising an n-channel type thin film transistor and a p-channel type thin film transistor, each comprising:

a semiconductor film formed over a substrate having an insulating surface;

a pair of source and drain regions in said semiconductor film;

a channel region in said semiconductor film; and

a gate insulating film adjacent to said channel region and a gate electrode adjacent to said channel region with said gate insulating film interposed therebetween,

wherein said n-channel type thin film transistor has at least one lightly doped region between said channel region and at least one of said source and drain regions,

wherein said p-channel type thin film transistor has no lightly doped region in said semiconductor film, and

wherein said source and drain regions of said p-channel type thin film transistor contain both phosphorus and boron.

40. A memory circuit according to claim 39 wherein the gate electrode is located over the channel region in each of the n-channel type thin film transistor and the p-channel type thin film transistor.

41. A memory circuit according to claim 39 wherein said p-channel type thin film transistor is complementarily connected to said n-channel type thin film transistor.

63. A memory circuit according to claim 39 further comprising an anodic oxide film on said gate electrode;

and a substantially triangular insulator adjacent to a side surface of said gate electrode, wherein said lightly doped region is provided under said substantially triangular insulator.

42. A decoder driver comprising an n-channel type thin film transistor and a p-channel type thin film transistor, each comprising:

a semiconductor film formed over a substrate having an insulating surface;

a pair of source and drain regions in said semiconductor film;

a channel region in said semiconductor film; and

a gate insulating film adjacent to said channel region and a gate electrode adjacent to said channel region with said gate insulating film interposed therebetween,

wherein said n-channel type thin film transistor has at least one lightly doped region between said channel region and at least one of said source and drain regions,

wherein said p-channel type thin film transistor has no lightly doped region in said semiconductor film, and

wherein said source and drain regions of said p-channel type thin film transistor contain both phosphorus and boron.

43. A decoder driver according to claim 42 wherein the gate electrode is located over the channel region in each of the n-channel type thin film transistor and the p-channel type thin film transistor.

44. A decoder driver according to claim 42 wherein said p-channel type thin film transistor is complementarily connected to said n-channel type thin film transistor.

64. A decoder driver according to claim 42 further comprising an anodic oxide film on said gate electrode;

and a substantially triangular insulator adjacent to a side surface of said gate electrode, wherein said lightly doped region is provided under said substantially triangular insulator.