Display device comprising a thin film transistor and a storage capacitor

• US 9,466,622 B2
• Filed: 01/14/2016
• Issued: 10/11/2016
• Est. Priority Date: 08/31/1999
• Status: Expired due to Fees

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Shibata, Hiroshi, Isobe, Atsuo
• Primary Examiner(s): NGO, NGAN V
• Application Number:
  US14/995,442
• Publication Number:
  US 20160133656A1
• Time in Patent Office: 271 Days
• US Class Current: 1/1
• CPC Class Codes: G02F 1/133345 Insulating layers G02F1/1335, G02F1/1337, G02F1/135, G02F1/136 take precedence
• CPC Class Codes: G02F 1/13454 Drivers integrated on the active matrix substrate G02F1/136277 takes precedence
• CPC Class Codes: G02F 1/136209 Light shielding layers, e.g. black matrix, incorporated in the active matrix substrate, e.g. structurally associated with the switching element
• CPC Class Codes: G02F 1/136213 Storage capacitors associated with the pixel electrode
• CPC Class Codes: G02F 1/136227 Through-hole connection of the pixel electrode to the active element through an insulation layer
• CPC Class Codes: G02F 1/136277 formed on a semiconductor substrate, e.g. of silicon
• CPC Class Codes: G02F 1/136286 Wiring, e.g. gate line, drain line
• CPC Class Codes: G02F 1/1368 in which the switching element is a three-electrode device G02F1/136277 takes precedence
• CPC Class Codes: H01L 27/12 the substrate being other than a semiconductor body, e.g. an insulating body
• 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 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 27/1255 integrated with passive devices, e.g. auxiliary capacitors
• CPC Class Codes: H01L 29/4908 for thin film semiconductor, e.g. gate of TFT
• CPC Class Codes: H01L 29/786 Thin film transistors, i.e. transistors with a channel being at least partly a thin film transistors having only the source or the drain region on an insulator layer H01L29/0653; thin film FinFETs H01L29/785
• CPC Class Codes: H01L 29/78633 with a light shield
• CPC Class Codes: H10K 59/12 Active-matrix OLED [AMOLED] displays
• CPC Class Codes: H10K 59/1213 the pixel elements being TFTs
• CPC Class Codes: H10K 59/1216 the pixel elements being capacitors
• CPC Class Codes: H10K 59/123 Connection of the pixel electrodes to the thin film transistors [TFT]
• CPC Class Codes: H10K 59/131 Interconnections, e.g. wiring lines or terminals

Abstract

To provide a liquid crystal display device having high quality display by obtaining a high aperture ratio while securing a sufficient storage capacitor (Cs), and at the same time, by dispersing a load (a pixel writing-in electric current) of a capacitor wiring in a timely manner to effectively reduce the load. A scanning line is formed on a different layer from a gate electrode and the capacitor wiring is arranged so as to be parallel with a signal line. Each pixel is connected to the individually independent capacitor wiring via a dielectric. Therefore, variations in the electric potential of the capacitor wiring caused by a writing-in electric current of a neighboring pixel can be avoided, whereby obtaining satisfactory display images.

Claims

1. A display device comprising:

a pixel provided with a thin film transistor and a storage capacitor;

a scanning line; and

a signal line provided in a direction orthogonal to the scanning line,

wherein a semiconductor film is provided over the scanning line and includes a portion to be a source region, a drain region, a channel formation region of the thin film transistor, and a portion to be a lower electrode of the storage capacitor,

wherein an insulating film is provided over the semiconductor film,

wherein a gate electrode is provided over the portion to be the channel formation region of the semiconductor film and is electrically connected to the scanning line with the insulating film interposed therebetween,

wherein an upper electrode of the storage capacitor is provided over the portion to be the lower electrode with the insulating film interposed therebetween,

wherein the semiconductor film which is over the scanning line is provided in parallel to a substrate,

wherein a part of a lower surface of the upper electrode of the storage capacitor is positioned lower than a lower surface of the gate electrode,

wherein the source region, the drain region, and the channel formation region of the thin film transistor include a region overlapped with the scanning line, and

wherein the scanning line has light blocking characteristics.

2. The display device according to claim 1, wherein the gate electrode is a conductive film formed of poly-Si doped with an impurity element imparting a conductivity type, WSi_X (X=2.0 to 2.8), Al, Ta, W, Cr or Mo, or a film laminating the conductive films selected therefrom.

3. The display device according to claim 1, wherein the scanning line is a conductive film formed of poly-Si doped with an impurity imparting a conductivity type, WSi_X (X=2.0 to 2.8), Al, Ta, W, Cr or Mo, or a film laminating the conductive films selected therefrom.

4. The display device according to claim 1, wherein the signal line is a film mainly composed of Al, W, Ti or TiN, or a film laminating the conductive films selected therefrom.

5. The display device according to claim 1, wherein the upper electrode of the storage capacitor is a conductive film formed of poly-Si doped with an impurity imparting a conductivity type, WSi_X (X=2.0 to 2.8), Al, Ta, W, Cr or Mo, or a film laminating the conductive films selected therefrom.

6. The display device according to claim 1, wherein the display device is incorporated in one selected from the group consisting of a personal computer, a video camera, a mobile computer, a goggle type display, a player using a recording medium, and a digital camera.

7. A display device comprising:

a pixel provided with a thin film transistor and a storage capacitor;

a scanning line; and

a signal line provided in a direction orthogonal to the scanning line,

wherein a semiconductor film is provided over the scanning line and includes a portion to be a source region, a drain region, a channel formation region of the thin film transistor, and a portion to be a lower electrode of the storage capacitor,

wherein an insulating film is provided over the semiconductor film,

wherein a gate electrode is provided over the portion to be the channel formation region of the semiconductor film and is electrically connected to the scanning line with the insulating film interposed therebetween,

wherein an upper electrode of the storage capacitor is provided over the portion to be the lower electrode with the insulating film interposed therebetween,

wherein, the semiconductor film which is over the scanning line is provided in parallel to a substrate,

wherein the signal line is provided over the gate electrode and the upper electrode,

wherein a part of a lower surface of the upper electrode of the storage capacitor is positioned lower than a lower surface of the gate electrode,

wherein the source region, the drain region, and the channel formation region of the thin film transistor include a region overlapped with the scanning line, and

wherein the scanning line has light blocking characteristics.

8. The display device according to claim 7, wherein the gate electrode is a conductive film formed of poly-Si doped with an impurity element imparting a conductivity type, WSi_X (X=2.0 to 2.8), Al, Ta, W, Cr or Mo, or a film laminating the conductive films selected therefrom.

9. The display device according to claim 7, wherein the scanning line is a conductive film formed of poly-Si doped with an impurity imparting a conductivity type, WSi_X (X=2.0 to 2.8), Al, Ta, W, Cr or Mo, or a film laminating the conductive films selected therefrom.

10. The display device according to claim 7, wherein the signal line is a film mainly composed of Al, W, Ti or TiN, or a film laminating the conductive films selected therefrom.

11. The display device according to claim 7, wherein the upper electrode of the storage capacitor is a conductive film formed of poly-Si doped with an impurity imparting a conductivity type, WSi_X (X=2.0 to 2.8), Al, Ta, W, Cr or Mo, or a film laminating the conductive films selected therefrom.

12. The display device according to claim 7, wherein the display device is incorporated in one selected from the group consisting of a personal computer, a video camera, a mobile computer, a goggle type display, a player using a recording medium, and a digital camera.

13. A display device comprising:

a pixel provided with a thin film transistor and a storage capacitor;

a scanning line; and

a signal line provided in a direction orthogonal to the scanning line,

wherein a semiconductor film is provided over the scanning line and includes a portion to be a source region, a drain region, a channel formation region of the thin film transistor, and a portion to be a lower electrode of the storage capacitor,

wherein an insulating film is provided over the semiconductor film,

wherein a gate electrode is provided over the portion to be the channel formation region of the semiconductor film and is electrically connected to the scanning line with the insulating film interposed therebetween,

wherein an upper electrode of the storage capacitor is provided over the portion to be the lower electrode with the insulating film interposed therebetween,

wherein the semiconductor film which is over the scanning line is provided in parallel to a substrate,

wherein a part of a lower surface of the upper electrode of the storage capacitor is positioned lower than a lower surface of the gate electrode,

wherein the signal line is provided over the gate electrode and the upper electrode,

wherein a light shielding film is provided over the signal line and provided so as to overlap with the semiconductor film,

wherein the source region, the drain region, and the channel formation region of the thin film transistor include a region overlapped with the scanning line, and

wherein the scanning line has light blocking characteristics.

14. The display device according to claim 13, wherein the gate electrode is a conductive film formed of poly-Si doped with an impurity element imparting a conductivity type, WSi_X (X=2.0 to 2.8), Al, Ta, W, Cr or Mo, or a film laminating the conductive films selected therefrom.

15. The display device according to claim 13, wherein the scanning line is a conductive film formed of poly-Si doped with an impurity imparting a conductivity type, WSi_X (X=2.0 to 2.8), Al, Ta, W, Cr or Mo, or a film laminating the conductive films selected therefrom.

16. The display device according to claim 13, wherein the signal line is a film mainly composed of Al, W, Ti or TiN, or a film laminating the conductive films selected therefrom.

17. The display device according to claim 13, wherein the upper electrode of the storage capacitor is a conductive film formed of poly-Si doped with an impurity imparting a conductivity type, WSi_X (X=2.0 to 2.8), Al, Ta, W, Cr or Mo, or a film laminating the conductive films selected therefrom.

18. The display device according to claim 13, wherein the display device is incorporated in one selected from the group consisting of a personal computer, a video camera, a mobile computer, a goggle type display, a player using a recording medium, and a digital camera.