Electro-optical device and electronic device

• US 8,853,696 B1
• Filed: 05/26/2000
• Issued: 10/07/2014
• Est. Priority Date: 06/04/1999
• Status: Expired due to Fees

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei, Koyama, Jun, Yamamoto, Kunitaka, Konuma, Toshimitsu
• Primary Examiner(s): GEBREMARIAM, SAMUEL A
• Application Number:
  US09/578,895
• Time in Patent Office: 5,247 Days
• Field of Search: 257/59, 257/72, 257/347, 257/344
• US Class Current: 257/59
• CPC Class Codes: H01L 27/1218 with a particular composition or structure of the substrate
• CPC Class Codes: H01L 27/1255 integrated with passive devices, e.g. auxiliary capacitors
• 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 29/78621 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: H01L 29/78645 with multiple gate
• 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
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 33/08 with a plurality of light emitting regions, e.g. laterally discontinuous light emitting layer or photoluminescent region integrated within the semiconductor body H01L27/15 takes precedence
• CPC Class Codes: H10K 2102/3026 Top emission
• CPC Class Codes: H10K 50/84 Passivation; Containers; Encapsulations
• CPC Class Codes: H10K 50/841 Self-supporting sealing arrangements
• CPC Class Codes: H10K 50/8426 Peripheral sealing arrangements, e.g. adhesives, sealants
• CPC Class Codes: H10K 50/846 comprising getter material or desiccants
• CPC Class Codes: H10K 50/87 Arrangements for heating or cooling
• 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 59/123 Connection of the pixel electrodes to the thin film transistors [TFT]
• CPC Class Codes: H10K 59/38 comprising colour filters or colour changing media [CCM]
• CPC Class Codes: H10K 59/8722 : Peripheral sealing arrangements, e.g. adhesives, sealants
• CPC Class Codes: H10K 59/874 : including getter material or desiccant
• CPC Class Codes: H10K 59/8794 : Arrangements for heating and cooling

Abstract

An object of the present invention is to provide an EL display device having a high operation performance and reliability.

The switching TFT 201 formed within a pixel has a multi-gate structure, which is a structure which imposes an importance on reduction of OFF current value. Further, the current control TFT 202 has a channel width wider than that of the switching TFT to make a structure appropriate for flowing electric current. Morever, the LDD region 33 of the current control TFT 202 is formed so as to overlap a portion of the gate electrode 35 to make a structure which imposes importance on prevention of hot carrier injection and reduction of OFF current value.

Claims

1. An electroluminescence display device comprising:

a substrate; and

a plurality of pixels over the substrate, each of the plurality of pixels comprising;

a first thin film transistor;

a second thin film transistor comprising at least two thin film transistors; and

an electroluminescence element comprising an organic layer interposed between a pair of electrodes,

wherein one of the pair of electrodes is electrically connected to the second thin film transistor,

wherein the first thin film transistor comprises at least two channel regions in an active layer, at least two gate electrodes corresponding to the channel regions, over the active layer with a gate insulating film interposed therebetween, and an impurity region interposed between the channel regions, and

wherein the at least two thin film transistors and the electroluminescence element are connected in series.

2. An electroluminescence display device according to claim 1,

wherein the first thin film transistor is a switching thin film transistor and the second thin film transistor is a current control thin film transistor.

3. An electroluminescence display device according to claim 1,

wherein each of the first and second thin film transistors has at least one lightly doped impurity region between a channel region and one of a drain region and the impurity region.

4. An electroluminescence display device comprising:

a substrate; and

a plurality of pixels over the substrate, each of the plurality of pixels comprising;

a switching element comprising an active layer and at least first and second gate electrodes adjacent to the active layer with a gate insulating film interposed therebetween;

a current control element comprising at least two thin film transistors; and

an electroluminescence element comprising an organic layer interposed between a pair of electrodes,

wherein one of the pair of electrodes is electrically connected to the current control element, and

wherein the at least two thin film transistors and the electroluminescence element are connected in series.

5. An electroluminescence display device according to claim 4,

a channel width of the current control element is greater than a channel width of the switching element.

6. An electroluminescence display device according to claim 4,

wherein each of the switching element and the current control element has at least one lightly doped impurity region.

7. An electroluminescence display device according to claim 4,

wherein the substrate comprises a material selected from the group consisting of a glass, a glass ceramic, a quartz, a silicon, a ceramic, a metal, and a plastic.

8. An electroluminescence display device comprising:

a substrate; and

a plurality of pixels over the substrate, each of the plurality of pixels comprising;

a switching element comprising at least two thin film transistors;

a current control element comprising at least two thin film transistors; and

an electroluminescence element comprising an organic layer interposed between a pair of electrodes,

wherein one of the pair of electrodes is electrically connected to the current control element, and

wherein the at least two thin film transistors in the current control element and the electroluminescence element are connected in series.

9. An electroluminescence display device according to claim 8,

a channel width of the current control element is greater than a channel width of the switching element.

10. An electroluminescence display device according to claim 8,

wherein each of the switching element and the current control element has at least one lightly doped impurity region.

11. An electroluminescence display device according to claim 8,

wherein the substrate comprises a material selected from the group consisting of a glass, a glass ceramic, a quartz, a silicon, a ceramic, a metal, and a plastic.

12. An electroluminescence display device comprising:

a substrate; and

a plurality of pixels over the substrate, each of the plurality of pixels comprising;

a first thin film transistor;

a second thin film transistor comprising at least two channel regions; and

an electroluminescence element comprising an organic layer interposed between a pair of electrodes,

wherein one of the pair of electrodes is electrically connected to the second thin film transistor,

wherein the first thin film transistor comprises at least two channel regions in an active layer, at least two gate electrodes corresponding to the channel regions, over the active layer with a gate insulating film interposed therebetween, and an impurity region interposed between the channel regions, and

wherein the at least two channel regions in the second thin film transistor and the electroluminescence element are connected in series.

13. An electroluminescence display device according to claim 12,

wherein the first thin film transistor is a switching thin film transistor and the second thin film transistor is a current control thin film transistor.

14. An electroluminescence display device according to claim 12,

wherein the substrate comprises a material selected from the group consisting of a glass, a glass ceramic, a quartz, a silicon, a ceramic, a metal, and a plastic.

15. An electroluminescence display device comprising:

a substrate; and

a plurality of pixels over the substrate, each of the plurality of pixels comprising;

a first thin film transistor comprising at least two channel regions in a first semiconductor film;

a second thin film transistor comprising at least two channel regions in a second semiconductor film; and

an electroluminescence element comprising an organic layer interposed between a pair of electrodes,

wherein one of the pair of electrodes is electrically connected to the second thin film transistor, and

wherein the at least two channel regions in the second semiconductor film and the electroluminescence element are connected in series.

16. An electroluminescence display device according to claim 15,

wherein the first thin film transistor is a switching thin film transistor and the second thin film transistor is a current control thin film transistor.

17. An electroluminescence display device according to claim 15,

wherein the substrate comprises a material selected from the group consisting of a glass, a glass ceramic, a quartz, a silicon, a ceramic, a metal, and a plastic.