Electronic device

• US 6,670,637 B2
• Filed: 02/26/2002
• Issued: 12/30/2003
• Est. Priority Date: 10/29/1999
• Status: Expired due to Term

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Konuma, Toshimitsu, Koyama, Jun, Yamazaki, Shunpei, Mizukami, Mayumi, Inukai, Kazutaka
• Primary Examiner(s): Thomas, Tom F
• Assistant Examiner(s): TRAN, THIEN F
• Application Number:
  US10/083,004
• Publication Number:
  US 20020134979A1
• Time in Patent Office: 672 Days
• Field of Search: 257/59, 257/72, 257/350, 257/351, 257/387, 257/408, 349/42, 349/43, 349/46
• US Class Current: 257/59
• CPC Class Codes: H01L 27/1222 with a particular composition, shape or crystalline structure of the active layer
• CPC Class Codes: H01L 27/127 with a particular formation, treatment or patterning of the active layer specially adapted to the circuit arrangement
• CPC Class Codes: H01L 29/78621 with LDD structure or an extension or an offset region or characterised by the doping profile
• CPC Class Codes: H01L 29/78627 with a significant overlap between the lightly doped drain and the gate electrode, e.g. GOLDD
• CPC Class Codes: H10K 50/84 Passivation; Containers; Encapsulations
• CPC Class Codes: H10K 50/8426 Peripheral sealing arrangements, e.g. adhesives, sealants
• CPC Class Codes: H10K 50/8428 Vertical spacers, e.g. arranged between the sealing arrangement and the OLED
• CPC Class Codes: H10K 50/846 comprising getter material or desiccants
• 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 71/00 Manufacture or treatment specially adapted for the organic devices covered by this subclass

Abstract

To provide an electronic device capable of bright image display. A pixel is structured such that a switching TFT and a current controlling TFT are formed on a substrate and an EL element is electrically connected to the current controlling TFT. A gate capacitor formed between a gate electrode of the current controlling TFT and an LDD region thereof holds a voltage applied to the gate electrode, and hence a capacitor (condenser) is not particularly necessary in the pixel, thereby making the effective light emission area of the pixel large.

Claims

1. An electronic device comprising:

a first thin film transistor on an insulating surface;

a first semiconductor island in the first thin film transistor;

a first source region and a first drain region in the first semiconductor island;

at least a first gate electrode adjacent to the first semiconductor island with a first gate insulating film interposed therebetween;

a second thin film transistor on the insulating surface;

a second semiconductor island in the second thin film transistor;

a second source region and a second drain region in the second semiconductor island;

at least an LDD region in the second semiconductor island;

at least a second gate electrode adjacent to the second semiconductor island with a second gate insulating interposed therebetween;

wherein the second gate electrode is electrically connected to the first drain region;

a light emitting layer,

wherein the light emitting layer is electrically connected to the second drain region,

wherein the second thin film transistor is a p-channel thin film transistor,

wherein at least a portion of the second semiconductor island is overlapped with the second gate electrode with the second gate insulating film interposed therebetween to form a capacitor.

2. A device according to claim 1,

wherein the LDD region of the second thin film transistor includes a p-type impurity element at a concentration in a range of 1× 10¹⁵ to 5×

10¹⁷ atoms/cm³.

3. A device according to claim 1,

wherein the electronic device is in combination with an electric apparatus,

wherein the electric apparatus is one selected from the group consisting of an EL display, a video camera, a head mount type display, an image reproduction apparatus including a recording medium, a portable computer, a personal computer, a cellular telephone, a sound reproduction device.

4. A device according to claim 1, further comprising:

at least an insulating film over the first and second thin film transistors;

a first electrode over the insulating film;

the light emitting layer over the first electrode;

a second electrode over the light emitting layer.

5. A device according to claim 4,

wherein the insulating film comprises an organic material.

6. A device according to claim 4,

wherein one of the first and second electrodes is an anode while the other is a cathode.

7. An electronic device comprising:

a first thin film transistor on an insulating surface;

a first semiconductor island in the first thin film transistor;

a first source region and a first drain region in the first semiconductor island;

at least a first gate electrode adjacent to the first semiconductor island with a first gate insulating film interposed therebetween;

a second thin film transistor on the insulating surface;

a second semiconductor island in the second thin film transistor;

a second source region and a second drain region in the second semiconductor island;

at least an LDD region in the second semiconductor island;

at least a second gate electrode adjacent to the second semiconductor island with a second gate insulating interposed therebetween;

wherein the second gate electrode is electrically connected to the first drain region;

a light emitting layer,

wherein the light emitting layer is electrically connected to the second drain region,

wherein the second thin film transistor is a p-channel thin film transistor,

wherein at least a portion of the second semiconductor island is overlapped with the second gate electrode with the second gate insulating film interposed therebetween to form a capacitor,

wherein the first thin film transistor has a multi-gate structure.

8. A device according to claim 7,

wherein the LDD region of the second thin film transistor includes a p-type impurity element at a concentration in a range of 1× 10¹⁵ to 5×

10¹⁷ atoms/cm³.

9. A device according to claim 7,

wherein the electronic device is in combination with an electric apparatus,

wherein the electric apparatus is one selected from the group consisting of an EL display, a video camera, a head mount type display, an image reproduction apparatus including a recording medium, a portable computer, a personal computer, a cellular telephone, a sound reproduction device.

10. A device according to claim 7, further comprising:

at least an insulating film over the first and second thin film transistors;

a first electrode over the insulating film;

the light emitting layer over the first electrode;

a second electrode over the light emitting layer.

11. A device according to claim 10,

wherein the insulating film comprises an organic material.

12. A device according to claim 10,

wherein one of the first and second electrodes is an anode while the other is a cathode.

13. An electronic device comprising a pixel portion and a driver circuit portion, said electronic device comprising:

an n-channel thin film transistor in the driver circuit portion on an insulating surface;

a first semiconductor island in the n-channel thin film transistor;

a first source region and a first drain region in the first semiconductor island;

at least a first LDD region in the first semiconductor island;

at least a first gate electrode adjacent to the first semiconductor island with a first gate insulating interposed therebetween;

a first thin film transistor in the pixel portion on the insulating surface;

a second semiconductor island in the first thin film transistor;

a second source region and a second drain region in the second semiconductor island;

at least a second gate electrode adjacent to the second semiconductor island with a second gate insulating film interposed therebetween;

a second thin film transistor in the pixel portion on the insulating surface;

a third semiconductor island in the second thin film transistor;

a third source region and a third drain region in the third semiconductor island;

at least a second LDD region in the third semiconductor island;

at least a third gate electrode adjacent to the third semiconductor island with a third gate insulating interposed therebetween;

wherein the third gate electrode is electrically connected to the second drain region;

a light emitting layer;

wherein the light emitting layer is electrically connected to the third drain region;

wherein the second thin film transistor is a p-channel thin film transistor;

wherein at least a portion of the third semiconductor island is overlapped with the third gate electrode with the third gate insulating film interposed therebetween to form a capacitor.

14. A device according to claim 13,

wherein the second LDD region of the second thin film transistor includes a p-type impurity element at a concentration in a range of 1× 10¹⁵ to 5×

10¹⁷ atoms/cm³.

15. A device according to claim 13,

wherein the electronic device is in combination with an electric apparatus,

wherein the electric apparatus is one selected from the group consisting of an EL display, a video camera, a head mount type display, an image reproduction apparatus including a recording medium, a portable computer, a personal computer, a cellular telephone, a sound reproduction device.

16. A device according to claim 13, further comprising:

at least an insulating film over the first, second and third thin film transistors;

a first electrode over the insulating film;

the light emitting layer over the first electrode;

a second electrode over the light emitting layer.

17. A device according to claim 16,

wherein the insulating film comprises an organic material.

18. A device according to claim 16,

wherein one of the first and second electrodes is an anode while the other is a cathode.

19. An electronic device comprising a pixel portion and a driver circuit portion, said electronic device comprising:

an n-channel thin film transistor in the driver circuit portion on an insulating surface;

a first semiconductor island in the n-channel thin film transistor;

a first source region and a first drain region in the first semiconductor island;

at least a first LDD region in the first semiconductor island;

at least a first gate electrode adjacent to the first semiconductor island with a first gate insulating interposed therebetween;

a first thin film transistor in the pixel portion on the insulating surface;

a second semiconductor island in the first thin film transistor;

a second source region and a second drain region in the second semiconductor island;

at least a second gate electrode adjacent to the second semiconductor island with a second gate insulating film interposed therebetween;

a second thin film transistor in the pixel portion on the insulating surface;

a third semiconductor island in the second thin film transistor;

a third source region and a third drain region in the third semiconductor island;

at least a second LDD region in the third semiconductor island;

at least a third gate electrode adjacent to the third semiconductor island with a third gate insulating interposed therebetween;

wherein the third gate electrode is electrically connected to the second drain region;

a light emitting layer;

wherein the light emitting layer is electrically connected to the third drain region;

wherein the second thin film transistor is a p-channel thin film transistor;

wherein at least a portion of the third semiconductor island is overlapped with the third gate electrode with the third gate insulating film interposed therebetween to form a capacitor,

wherein the first thin film transistor has a multi-gate structure.

20. A device according to claim 19,

wherein the second LDD region of the second thin film transistor includes a p-type impurity element at a concentration in a range of 1× 10¹⁵ to 5×

10¹⁷ atoms/cm³.

21. A device according to claim 19,

wherein the electronic device is in combination with an electric apparatus,

wherein the electric apparatus is one selected from the group consisting of an EL display, a video camera, a head mount type display, an image reproduction apparatus including a recording medium, a portable computer, a personal computer, a cellular telephone, a sound reproduction device.

22. A device according to claim 19, further comprising:

at least an insulating film over the first, second and third thin film transistors;

a first electrode over the insulating film;

the light emitting layer over the first electrode;

a second electrode over the light emitting layer.

23. A device according to claim 22,

wherein the insulating film comprises an organic material.

24. A device according to claim 22,

wherein one of the first and second electrodes is an anode while the other is a cathode.