Electro-optical device and electronic device

• US 9,123,854 B2
• Filed: 09/20/2013
• Issued: 09/01/2015
• 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:
  US14/032,220
• Publication Number:
  US 20140014963A1
• Time in Patent Office: 711 Days
• Field of Search: 257/59, 257/72, 257/344
• US Class Current: 1/1
• 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 a gate electrode electrically connected to the first thin film transistor; and

an electroluminescence element electrically connected to the second thin film transistor,

wherein the first thin film transistor comprises at least two channel regions which are electrically connected in series and an impurity region interposed between the two channel regions,

wherein the second thin film transistor comprises at least two channel regions which are electrically connected in series, and

wherein the impurity region of the first thin film transistor has substantially the same impurity concentration as a source region or a drain region of the first thin film transistor.

2. An electroluminescence display device according to claim 1, a channel width of the second thin film transistor is greater than a channel width of the first thin film transistor.

3. 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.

4. An electroluminescence display device according to claim 1, wherein an equation of W2/L2≧

5×

W1/L1 establishes where a channel length of the second thin film transistor is L2 , a channel width of the second thin film transistor is W2, a channel length of the first thin film transistor is L1 and a channel width of the first thin film transistor is W1.

5. An electroluminescence display device according to claim 4, wherein the channel length of the second thin film transistor (L2) is 0.1 to 50 μ

m, the channel width of the second thin film transistor (W2) is 0.5 to 30 μ

m, the channel length of the first thin film transistor (L1 ) is 0.2 to 18 μ

m and the channel width of the first thin film transistor (W1) is 0.1 to 5 μ

m.

6. An electroluminescence display device according to claim 1, 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.

7. 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 a gate electrode electrically connected to the first thin film transistor; and

an electroluminescence element electrically connected to the second thin film transistor,

wherein the first thin film transistor comprises at least two channel regions which are electrically connected in series, an impurity region interposed between the two channel regions, and a lightly doped impurity region between one of the two channel regions and one of a drain region and a source region,

wherein the second thin film transistor has a lightly doped impurity region between a channel region and one of a drain region and a source region,

wherein the lightly doped impurity region of the first thin film transistor does not overlap a gate electrode of the first thin film transistor and the lightly doped impurity region of the second thin film transistor overlaps the gate electrode of the second thin film transistor at least partly, and

wherein the impurity region of the first thin film transistor has substantially the same impurity concentration as the source region or the drain region of the first thin film transistor.

8. An electroluminescence display device according to claim 7, a channel width of the second thin film transistor is greater than a channel width of the first thin film transistor.

9. An electroluminescence display device according to claim 7, 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.

10. An electroluminescence display device according to claim 7, wherein an equation of W2/L2≧

5×

W1/L1 establishes where a channel length of the second thin film transistor is L2 , a channel width of the second thin film transistor is W2, a channel length of the first thin film transistor is L1 and a channel width of the first thin film transistor is W1.

11. An electroluminescence display device according to claim 10, wherein the channel length of the second thin film transistor (L2) is 0.1 to 50 μ

m, the channel width of the second thin film transistor (W2) is 0.5 to 30 μ

m, the channel length of the first thin film transistor (L1 ) is 0.2 to 18 μ

m and the channel width of the first thin film transistor (W1) is 0.1 to 5 μ

m.

12. An electroluminescence display device according to claim 7, 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.

13. A portable telephone 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 a gate electrode electrically connected to the first thin film transistor; and

an electroluminescence element electrically connected to the second thin film transistor,

wherein the first thin film transistor comprises at least two channel regions which are electrically connected in series and an impurity region interposed between the two channel regions,

wherein the second thin film transistor comprises at least two channel regions which are electrically connected in series, and

wherein the impurity region of the first thin film transistor has substantially the same impurity concentration as a source region or a drain region of the first thin film transistor.

14. A portable telephone according to claim 13, 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.

15. A portable telephone according to claim 13, wherein an equation of W2/L2≧

5×

W1/L1 is established where a channel length of the second thin film transistor is L2 , a channel width of the second thin film transistor is W2, a channel length of the first thin film transistor is L1 and a channel width of the first thin film transistor is W1.

16. A portable telephone according to claim 15, wherein the channel length of the second thin film transistor (L2) is 0.1 to 50 μ

m, the channel width of the second thin film transistor (W2) is 0.5 to 30 μ

m, the channel length of the first thin film transistor (L1 ) is 0.2 to 18 μ

m and the channel width of the first thin film transistor (W1) is 0.1 to 5 μ

m.

17. A portable telephone according to claim 13, 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.