Pixel TFT and driver TFT having different gate insulation width

• US 6,278,131 B1
• Filed: 01/05/2000
• Issued: 08/21/2001
• Est. Priority Date: 01/11/1999
• Status: Expired due to Term

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Shibata, Hiroshi, Fukunaga, Takeshi, Koyama, Jun, Yamazaki, Shunpei
• Primary Examiner(s): Abraham, Fetsum
• Application Number:
  US09/477,865
• Time in Patent Office: 594 Days
• Field of Search: 257/59, 257/72, 257/347, 257/350, 257/351, 257/357
• 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 27/1255 integrated with passive devices, e.g. auxiliary capacitors
• CPC Class Codes: H01L 27/1277 using a crystallisation promoting species, e.g. local introduction of Ni catalyst
• 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 29/78645 with multiple gate

Abstract

A semiconductor device having high reliability, in which TFTs with appropriate structures for the circuit functions are arranged, is provided. Gate insulating films (115) and (116) of a driver TFT are designed thinner than a gate insulating film (117) of a pixel TFT in a semiconductor device having a driver circuit and a pixel section on the same substrate. In addition, the gate insulating films (115) and (116) of the driver TFT and a dielectric (118) of a storage capacitor are formed at the same time, so that the dielectric (118) may be extremely thin, and a large capacity can be secured.

Claims

1. A semiconductor device having a driver circuit section and a pixel section on the same substrate, wherein:

a driver TFT of said driver circuit section, and a pixel TFT of said pixel section, each have a gate insulating film with a mutually differing film thickness; and

a film thickness of a dielectric of a storage capacitor formed in said pixel section is the same as a film thickness of the gate insulating film of said driver TFT.

3. The semiconductor device according to claim 1, wherein:

a film thickness of the gate insulating film of said pixel TFT is between 50 and 200 nm; and

a film thickness of the gate insulating film of said driver TFT is between 5 and 50 nm.

4. The semiconductor device according to claim 1, wherein:

said storage capacitor includes an electrode from a semiconductor film; and

an element selected from a group consisting of nickel, cobalt, palladium, germanium, platinum, iron, or copper is included in said electrode, at a concentration of 1×

10¹⁹ atoms/cm³ or greater.

5. The semiconductor device according to claim 4, wherein a periodic table group 15 element is included in said electrode at a concentration of between 5×

10¹⁸ and 1×

10²⁰ atoms/cm³.

6. Electric equipment wherein the semiconductor device according to claim 1 is used as a display section.

2. A semiconductor device having a driver circuit section and a pixel section on the same substrate, wherein:

a film thickness of a gate insulating film of a driver TFT of said driver circuit section is thinner than the film thickness of a gate insulating film of a pixel TFT of said pixel section; and

a film thickness of a dielectric of a storage capacitor formed in said pixel section is the same as the film thickness of the gate insulating film of said driver TFT.

7. A semiconductor device having at least one active matrix display device, said display device comprising:

a substrate;

a pixel electrode formed over said substrate;

a first semiconductor island formed over said substrate, having at least one channel forming region and a region as a first capacitor forming electrode of a storage capacitor;

a first insulating film formed on said first semiconductor island, said first insulating film including a first gate insulating film on said channel forming region and a capacitor forming insulating film on said region as the capacitor forming electrode;

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

a second capacitor forming electrode over said region as the first capacitor forming electrode with said capacitor forming insulating film interposed therebetween;

a first thin film transistor for switching said pixel electrode, said first thin film transistor comprising said channel forming region, said gate insulating film and said gate electrode;

a driver circuit comprising at least one second thin film transistor formed over said substrate, said second thin film transistor comprising a second semiconductor island including a channel forming region, a second gate insulating film formed on said second semiconductor island and a second gate electrode formed on said second gate insulating film,

wherein said capacitor forming insulating film has a same thickness as said second gate insulating film and a smaller thickness than said first gate insulating film.

8. The semiconductor device according to claim 7 wherein the thickness of said capacitor forming insulating film is 5 to 50 nm and the thickness of said first gate insulating film is 50 to 200 nm.

9. The semiconductor device according to claim 7 wherein said active matrix display device is a liquid crystal display device or an EL display device.

10. The semiconductor device according to claim 7 wherein said semiconductor device is a portable telephone.

11. The semiconductor device according to claim 7 wherein said semiconductor device is a video camera.

12. The semiconductor device according to claim 7 wherein said semiconductor device is a mobile computer.

13. The semiconductor device according to claim 7 wherein said semiconductor device is a goggle type display.

14. The semiconductor device according to claim 7 wherein said semiconductor device is a projector.

15. The semiconductor device according to claim 7 wherein said semiconductor device is a personal computer.

16. The semiconductor device according to claim 7 wherein said semiconductor device is an electronic game equipment.

17. The semiconductor device according to claim 7 wherein said semiconductor device is an image reproduction device.

18. The semiconductor device according to claim 7 wherein said semiconductor device is a digital camera.

19. A semiconductor device having at least one active matrix display device, said display device comprising:

a substrate;

a pixel electrode formed over said substrate;

a first semiconductor island formed over said substrate, having at least one channel forming region and a region as a first capacitor forming electrode of a storage capacitor;

a first insulating film formed on said first semiconductor island, said first insulating film including a first gate insulating film on said channel forming region and a capacitor forming insulating film on said region as the capacitor forming electrode;

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

a second capacitor forming electrode over said region as the first capacitor forming electrode with said capacitor forming insulating film interposed therebetween;

a first thin film transistor for switching said pixel electrode, said first thin film transistor comprising said channel forming region, said gate insulating film and said gate electrode;

a driver circuit comprising at least one second thin film transistor formed over said substrate, said second thin film transistor comprising a second semiconductor island including a channel forming region, a second gate insulating film formed on said second semiconductor island and a second gate electrode formed on said second gate insulating film,

wherein said capacitor forming insulating film has a same thickness as said second gate insulating film and a smaller thickness than said first gate insulating film, and

wherein said second gate insulating film and said second capacitor forming insulating film are formed by thermal oxidation while said first gate insulating film is formed by thermal oxidation and a chemical vapor deposition.

20. The semiconductor device according to claim 19 wherein the thickness of said capacitor forming insulating film is 5 to 50 nm and the thickness of said first gate insulating film is 50 to 200 nm.

21. The semiconductor device according to claim 19 wherein said active matrix display device is a liquid crystal display device or an EL display device.

22. The semiconductor device according to claim 19 wherein said semiconductor device is a portable telephone.

23. The semiconductor device according to claim 19 wherein said semiconductor device is a video camera.

24. The semiconductor device according to claim 19 wherein said semiconductor device is a mobile computer.

25. The semiconductor device according to claim 19 wherein said semiconductor device is a goggle type display.

26. The semiconductor device according to claim 19 wherein said semiconductor device is a projector.

27. The semiconductor device according to claim 19 wherein said semiconductor device is a personal computer.

28. The semiconductor device according to claim 19 wherein said semiconductor device is an electronic game equipment.

29. The semiconductor device according to claim 19 wherein said semiconductor device is an image reproduction device.

30. The semiconductor device according to claim 19 wherein said semiconductor device is a digital camera.

31. A semiconductor device having at least one active matrix display device, said display device comprising:

a substrate;

a pixel electrode formed over said substrate;

a first semiconductor island formed over said substrate, having at least one channel forming region and a region as a first capacitor forming electrode of a storage capacitor;

a first insulating film formed on said first semiconductor island, said first insulating film including a first gate insulating film on said channel forming region and a capacitor forming insulating film on said region as the capacitor forming electrode;

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

a second capacitor forming electrode over said region as the first capacitor forming electrode with said capacitor forming insulating film interposed therebetween;

a first thin film transistor for switching said pixel electrode, said first thin film transistor comprising said channel forming region, said gate insulating film and said gate electrode;

a light shielding film located below at least said channel forming region of said first semiconductor island with an insulating film interposed therebetween; and

a driver circuit comprising at least one second thin film transistor formed over said substrate, said second thin film transistor comprising a second semiconductor island including a channel forming region, a second gate insulating film formed on said second semiconductor island and a second gate electrode formed on said second gate insulating film,

wherein said capacitor forming insulating film has a same thickness as said second gate insulating film and a smaller thickness than said first gate insulating film.

32. The semiconductor device according to claim 31 wherein the thickness of said capacitor forming insulating film is 5 to 50 nm and the thickness of said first gate insulating film is 50 to 200 nm.

33. The semiconductor device according to claim 31 wherein said active matrix display device is a liquid crystal display device or an EL display device.

34. The semiconductor device according to claim 31 wherein said semiconductor device is a portable telephone.

35. The semiconductor device according to claim 31 wherein said semiconductor device is a video camera.

36. The semiconductor device according to claim 31 wherein said semiconductor device is a mobile computer.

37. The semiconductor device according to claim 31 wherein said semiconductor device is a goggle type display.

38. The semiconductor device according to claim 31 wherein said semiconductor device is a projector.

39. The semiconductor device according to claim 31 wherein said semiconductor device is a personal computer.

40. The semiconductor device according to claim 31 wherein said semiconductor device is an electronic game equipment.

41. The semiconductor device according to claim 31 wherein said semiconductor device is an image reproduction device.

42. The semiconductor device according to claim 31 wherein said semiconductor device is a digital camera.