Gate insulated field effect transistors and method of manufacturing the same

• US 6,281,520 B1
• Filed: 09/09/1998
• Issued: 08/28/2001
• Est. Priority Date: 11/20/1990
• Status: Expired due to Fees

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei
• Primary Examiner(s): CLARK, JASMINE JHIHAN B
• Application Number:
  US09/149,291
• Time in Patent Office: 1,084 Days
• Field of Search: 257/66, 257/72, 257/59, 257/67, 257/57
• US Class Current: 257/66
• CPC Class Codes: G02F 1/136245 having complementary transistors
• CPC Class Codes: H01L 27/1214 comprising a plurality of TFTs formed on a non-semiconducting substrate, e.g. driving circuits for AMLCDs
• CPC Class Codes: H01L 29/66757 Lateral single gate single channel transistors with non-inverted structure, i.e. the channel layer is formed before the gate
• CPC Class Codes: H01L 29/78666 with normal-type structure, e.g. with top gate
• CPC Class Codes: H01L 29/78675 with normal-type structure, e.g. with top gate
• CPC Class Codes: H01L 29/78681 having a semiconductor body comprising AIIIBV or AIIBVI or AIVBVI semiconductor materials, or Se or Te
• CPC Class Codes: H01L 29/78684 having a semiconductor body comprising semiconductor materials of Group IV not being silicon, or alloys including an element of the group IV, e.g. Ge, SiN alloys, SiC alloys H01L29/7869 takes precedence
• CPC Class Codes: H01L 29/78696 characterised by the structure of the channel, e.g. multichannel, transverse or longitudinal shape, length or width, doping structure, or the overlap or alignment between the channel and the gate, the source or the drain, or the contacting structure of the channel H01L29/78612 takes precedence; transistors having a drain offset region or a lightly doped drain [LDD] H01L29/78621

Abstract

A thin film field effect transistors and manufacturing method for the same are described. The channel region of the transistor is spoiled by an impurity such as oxygen, carbon, nitrogen. The photosensitivity of the channel region is reduced by the spoiling impurity and therefore the transistor is endowed with immunity to illumination incident thereupon which would otherwise impair the normal operation of the transistor. The spoiling impurity is not introduced into transistors which are located in order not to receive light rays.

Claims

1. A liquid crystal device comprising:

a substrate having an insulating surface;

a plurality of switching elements provided over said substrate;

a plurality of first signal lines having a first side and a second side extending in a first direction over said substrate;

a plurality of second signal lines extending over said substrate in a second direction orthogonal to said first direction;

an organic resin film formed over the plurality of switching elements, the plurality of first signal lines and the plurality of second signal lines;

a plurality of pixel electrodes formed over said organic resin film and electrically connected to said plurality of switching elements; and

a liquid crystal layer adjacent to said plurality of pixel electrodes, wherein at least a portion of said plurality of first signal lines between the first side and the second side are completely covered by said plurality of pixel electrodes.

2. The device according to claim 1 wherein each of the plurality of switching elements comprises a thin film transistor of a type selected from the group consisting of a staggered type, a coplanar type, an inverted staggered type and an inverted coplanar type.

3. The device according to claim 1 wherein said liquid crystal material comprises a material selected from the group consisting of a ferroelectric liquid crystal material, a nematic liquid crystal material, a dispersion type liquid crystal and a polymer liquid crystal.

4. The device according to claim 1 wherein said liquid crystal material comprises a nematic liquid crystal of guest host type or dielectric anisotropic type.

5. The device according to claim 1 wherein each of said plurality of switching elements has an active region comprising crystalline silicon doped with hydrogen.

6. The device according to claim 1 wherein said device is a reflection type.

7. The device according to claim 1 wherein said device is a transmission type.

8. A liquid crystal device comprising:

a substrate having an insulating surface;

a plurality of switching elements provided over said substrate;

a plurality of first signal lines extending in a first direction over said substrate;

a plurality of second signal lines extending over said substrate in a second direction orthogonal to said first direction;

an organic resin film formed over the plurality of switching elements, the plurality of first signal lines and the plurality of second signal lines;

a plurality of pixel electrodes formed over said organic resin film and electrically connected to said plurality of switching elements; and

a liquid crystal layer adjacent to said plurality of pixel electrodes,

wherein said plurality of first signal lines extend below said plurality of pixel electrodes so that each of said plurality of pixel electrodes is divided into two parts as viewed from above.

9. The device according to claim 8 wherein each of the plurality of switching elements comprises a thin film transistor of a type selected from the group consisting of a staggered type, a coplanar type, an inverted staggered type and an inverted coplanar type.

10. The device according to claim 8 wherein said liquid crystal material comprises a material selected from the group consisting of a ferroelectric liquid crystal material, a nematic liquid crystal material, a dispersion type liquid crystal and a polymer liquid crystal.

11. The device according to claim 8 wherein said liquid crystal material comprises a nematic liquid crystal of guest host type or dielectric anisotropic type.

12. The device according to claim 8 wherein said device is a reflection type.

13. The device according to claim 8 wherein said device is a transmission type.

14. The device according to claim 8 wherein each of said plurality of switching elements has an active region comprising crystalline silicon doped with hydrogen.

15. A liquid crystal device comprising:

a substrate having an insulating surface;

at least one switching element provided over said substrate;

at least one signal line for supplying signals to said at least one switching element;

an interlayer insulating film comprising an organic material over said substrate covering said at least one switching element and said at least one signal line;

at least one pixel electrode formed over said interlayer insulating film; and

a liquid crystal layer adjacent to said pixel electrode,

wherein at least one signal line extends below a middle portion of said at least one pixel electrode.

16. The device according to claim 15 wherein each of the plurality of switching elements comprises a thin film transistor of a type selected from the group consisting of a staggered type, a coplanar type, an inverted staggered type and an inverted coplanar type.

17. The device according to claim 15 wherein said liquid crystal material comprises a material selected from the group consisting of a ferroelectric liquid crystal material, a nematic liquid crystal material, a dispersion type liquid crystal and a polymer liquid crystal.

18. The device according to claim 15 wherein said liquid crystal material comprises a nematic liquid crystal of guest host type or dielectric anisotropic type.

19. The device according to claim 15 wherein said device is a reflection type.

20. The device according to claim 15 wherein said device is a transmission type.

21. The device according to claim 15 wherein each of the said plurality of switching elements has an active region comprising crystalline silicon doped with hydrogen.

22. A liquid crystal device comprising:

a substrate having an insulating surface;

a plurality of switching elements provided over said substrate;

a plurality of first signal lines having a first side and a second side extending in a first direction over said substrate;

a plurality of second signal lines extending over said substrate in a second direction orthogonal to said first direction;

an interlayer insulating film formed over the plurality of switching elements;

a plurality of pixel electrodes formed over said interlayer insulating film and electrically connected to said plurality of switching elements; and

a liquid crystal layer adjacent to said plurality of pixel electrodes,

wherein a portion of said plurality of first signal lines between the first side and the second side are completely covered by said plurality of pixel electrodes.

23. The device according to claim 22 wherein said liquid crystal material comprises a material selected from the group consisting of a ferroelectric liquid crystal material, a nematic liquid crystal material, a dispersion type liquid crystal and polymer liquid crystal.

24. The device according to claim 22 wherein said liquid crystal material comprises a nematic liquid crystal of guest host type or dielectric anisotropic type.

25. The device according to claim 22 wherein said device is a reflection type.

26. The device according to claim 22 wherein said device is a transmission type.

27. A liquid crystal device comprising:

a substrate having an insulating surface;

a plurality of switching elements provided over said substrate;

a plurality of first signal lines extending in a first direction over said substrate;

a plurality of second signal lines extending over said substrate in a second direction orthogonal to said first direction;

an interlayer insulating film formed over the plurality of switching elements;

a plurality of pixel electrodes formed over said interlayer insulating film and electrically connected to said plurality of switching elements; and

a liquid crystal layer adjacent to said plurality of pixel electrodes,

wherein said plurality of first signal lines extend below said plurality of pixel electrodes so that each of said plurality of pixel electrodes is divided into two parts as viewed from above.

28. The device according to claim 27 wherein said liquid crystal material comprises a material selected from the group consisting of a ferroelectric liquid crystal material, a nematic liquid crystal material, a dispersion type liquid crystal and a polymer liquid crystal.

29. The device according to claim 27 wherein said liquid crystal material comprises a nematic liquid crystal of guest host type or dielectric anisotropic type.

30. The device according to claim 27 wherein said device is a reflection type.

31. The device according to claim 27 wherein said device is a transmission type.

32. A liquid crystal device comprising:

a substrate having an insulating surface;

at least one switching element provided over said substrate;

at least one signal line for supplying signals to said at least one switching element;

an interlayer insulating film over said substrate covering said at least one switching element and said at least one signal line;

at least one pixel electrode formed over said interlayer insulating film; and

a liquid crystal layer adjacent to said pixel electrode,

wherein said at least one signal line extends below a middle portion of said at least one pixel electrode.

33. The device according to claim 32 wherein said liquid crystal material comprises a material selected from the group consisting of a ferroelectric liquid crystal material, a nematic liquid crystal material, a dispersion type liquid crystal and a polymer liquid crystal.

34. The device according to claim 32 wherein said liquid crystal material comprises a nematic liquid crystal of guest host type or dielectric anisotropic type.

35. The device according to claim 32 wherein said device is a reflection type.

36. The device according to claim 32 wherein said device is a transmission type.

37. A liquid crystal device comprising:

a plurality of switching elements arranged in a matrix form;

a plurality of signal lines having a first side and a second side electrically connected to said plurality of switching elements;

an organic resin film formed over the plurality of switching elements and the plurality of signal lines;

a plurality of pixel electrodes formed over said organic resin film and electrically connected to said plurality of switching elements; and

a liquid crystal layer adjacent to said plurality of pixel electrodes,

wherein at least a portion of said plurality of signal lines between the first side and the second side is completely covered by said plurality of pixel electrodes.

38. The liquid crystal device according to claim 37 wherein said switching elements are insulated gate field effect transistors.

39. The liquid crystal device according to claim 38 wherein said signal lines are electrically connected to gate electrodes of said transistors.

40. A liquid crystal device comprising:

a plurality of switching elements arranged in a matrix form;

a plurality of first signal lines having a first side and a second side extending in a first direction and electrically connected to said switching elements;

a plurality of second signal lines extending in a second direction orthogonal to said first direction and electrically connected to said switching elements;

an interlayer insulating film formed over the plurality of switching elements;

an organic resin film formed on said interlayer insulating film;

a plurality of pixel electrodes formed over said organic resin film and electrically connected to said plurality of switching elements; and

a liquid crystal layer adjacent to said plurality of pixel electrodes,

wherein at least a portion of said plurality of first signal lines between the first side and the second side is completely covered by said plurality of pixel electrodes.

41. The device according to claim 40 wherein said switching elements are insulated gate field effect transistors.

42. The device according to claim 41 wherein said first signal lines are connected to gate electrodes of said transistors.

43. A liquid crystal device comprising:

a substrate having an insulating surface;

at least one switching element having at least one thin film transistor formed over said substrate, said thin film transistor comprising a crystalline semiconductor film and a channel region in said crystalline semiconductor film;

at least one signal line electrically connected to said switching element and extending in one direction over said substrate;

an organic resin film formed over said switching element and said signal line;

at least one pixel electrode formed over said organic resin film wherein said pixel electrode is electrically connected to said switching element;

a liquid crystal layer adjacent to said pixel electrode,

wherein at least a portion of said signal line is completely covered by said pixel electrode, and

wherein a total concentration of carbon, oxygen and nitrogen in said channel region is from 1×

10²⁰ atoms/cm³ to 20 atom %.

44. The semiconductor device according to claim 43 wherein said channel region contains boron at a concentration of from 1×

10¹⁵ to 5×

10¹⁷ atoms/cm³.

45. The device according to claim 43 wherein said transistor is selected from the group consisting of a staggered type, a coplanner type, an inverted staggered type and an inverted coplanner type.

46. A liquid crystal device comprising:

a substrate having an insulating surface;

at least one switching element having at least one thin film transistor formed over said substrate, said thin film transistor comprising a crystalline semiconductor including source, drain and channel regions;

at least one signal line electrically connected to said switching element and extending in one direction over said substrate;

an organic resin film formed over said switching element and said signal line;

at least one pixel electrode formed over said organic resin film wherein said pixel electrode is electrically connected to said switching element;

a liquid crystal layer adjacent to said pixel electrode,

wherein at least a portion of said signal line is completely covered by said pixel electrode, and

wherein a total concentration of carbon, oxygen and nitrogen in said source and drain regions is not higher than 7×

10¹⁹ atoms/cm³.

47. The semiconductor device according to claim 46 wherein said channel region contains boron at a concentration of from 1×

10¹⁵ to 5×

10¹⁷ atoms/cm³.

48. The device according to claim 46 wherein said transistor is selected from the group consisting of a staggered type, a coplanner type, an inverted staggered type and an inverted coplanner type.

49. A semiconductor device comprising:

a substrate having an insulating surface;

at least one pixel electrode formed over said substrate;

at least one switching element having at least one thin film transistor formed over said substrate for switching said pixel electrode, said thin film transistor comprising a crystalline semiconductor film and a channel region in said crystalline semiconductor film,

wherein a total concentration of carbon, oxygen and nitrogen in said channel region is from 1×

10²⁰ atoms/cm³ to 20 atom %.

50. The semiconductor device according to claim 49 wherein said channel region contains boron at a concentration of from 1×

10¹⁵ to 5×

10¹⁷ atoms/cm³.

51. The device according to claim 49 wherein said transistor is selected from the group consisting of a staggered type, a coplanner type, an inverted staggered type and an inverted coplanner type.

52. A semiconductor device comprising:

a substrate having an insulating surface;

at least one pixel electrode formed over said substrate;

at least one switching element having at least one thin film transistor formed over said substrate for switching said pixel electrode, said thin film transistor comprising a crystalline semiconductor film and a channel region in said crystalline semiconductor film; and

an organic resin film formed over said switching element, wherein said pixel electrode is formed over said organic resin film,

wherein a total concentration of carbon, oxygen and nitrogen in said channel region is from 1×

10²⁰ atoms/cm³ to 20 atom %.

53. The semiconductor device according to claim 52 wherein said channel region contains boron at a concentration of from 1×

10¹⁵ to 5×

10¹⁷ atoms/cm³.

54. The device according to claim 52 wherein said transistor is selected from the group consisting of a staggered type, a coplanner type, an inverted staggered type and an inverted coplanner type.

55. A semiconductor device comprising:

a substrate having an insulating surface;

at least one pixel electrode formed over said substrate;

at least one switching element having at least one thin film transistor formed over said substrate for switching said pixel electrode, said thin film transistor comprising a crystalline semiconductor film including source, drain and channel regions,

wherein a total concentration of carbon, oxygen and nitrogen in said source and drain regions is not higher than 7×

10¹⁹ atoms/cm³.

56. The semiconductor device according to claim 55 wherein said channel region contains boron at a concentration of from 1×

10¹⁵ to 5×

10¹⁷ atoms/cm³.

57. The device according to claim 55 wherein said transistor is selected from the group consisting of a staggered type, a coplanner type, an inverted staggered type and an inverted coplanner type.

58. A semiconductor device comprising:

a substrate having an insulating surface;

at least one pixel electrode formed over said substrate;

at least one switching element having at least one thin film transistor formed over said substrate for switching said pixel electrode, said thin film transistor including source, drain and channel regions; and

an organic resin film formed over said switching element, wherein said pixel electrode is formed over said organic resin film,

wherein a total concentration of carbon, oxygen and nitrogen in said source and drain regions is not higher than 7×

10¹⁹ atoms/cm³.

59. The semiconductor device according to claim 58 wherein said channel region contains boron at a concentration of from 1×

10¹⁵ to 5×

10¹⁷ atoms/cm³.

60. The device according to claim 58 wherein said transistor is selected from the group consisting of a staggered type, a coplanner type, an inverted staggered type and an inverted coplanner type.

61. A semiconductor device comprising:

a substrate having an insulating surface;

a plurality of switching elements formed over said substrate, each of said switching elements comprising a first thin film transistor;

a plurality of pixel electrodes electrically connected to said switching elements; and

a driver circuit comprising at least one second thin film transistor for driving said switching elements, said second thin film transistor comprising a crystalline semiconductor film including a channel region formed over said substrate,

wherein a total concentration of carbon, oxygen and nitrogen in said crystalline semiconductor film is not higher than 7×

10¹⁹ atoms/cm³.

62. The device according to claim 61 wherein each of said first and second thin film transistors is selected from the group consisting of a staggered type, a coplanner type, an inverted staggered type and an inverted coplanner type.

63. A semiconductor device comprising:

a substrate having an insulating surface;

a plurality of switching elements formed over said substrate, each of said switching elements comprising a first thin film transistor;

an organic resin film formed over said plurality of switching elements; and

a plurality of pixel electrodes formed over said organic resin film and electrically connected to said switching elements; and

a driver circuit comprising at least one second thin film transistor for driving said switching elements, said second thin film transistor comprising a crystalline semiconductor film including a channel region formed over said substrate,

wherein a total concentration of carbon, oxygen and nitrogen in said crystalline semiconductor film is not higher than 7×

10¹⁹ atoms/cm³.

64. The device according to claim 63 wherein each of said first and second thin film transistors is selected from the group consisting of a staggered type, a coplanner type, an inverted staggered type and an inverted coplanner type.

65. A semiconductor device comprising:

a substrate having an insulating surface;

a plurality of switching elements formed over said substrate, each of said switching elements comprising a first thin film transistor;

an organic resin film formed over said plurality of switching elements; and

a plurality of pixel electrodes formed over said organic resin film and electrically connected to said switching elements; and

a driver circuit comprising at least one second thin film transistor formed over said substrate for driving said switching elements, wherein each of said first and second thin film transistors comprises a crystalline semiconductor film including a channel region,

wherein a total concentration of carbon, oxygen and nitrogen in said crystalline semiconductor film of the second thin film transistor is not higher than 7×

10¹⁹ atoms/cm³, and

wherein a total concentration of carbon, oxygen and nitrogen in said crystalline semiconductor film of the first thin film transistor is 1×

10²⁰ atoms/cm³ to 20 atom %.

66. The device according to claim 65 wherein each of said first and second thin film transistors is selected from the group consisting of a staggered type, a coplanner type, an inverted staggered type and an inverted coplanner type.