EL display device having pixel electrode with projecting portions and manufacturing method thereof

• US 7,710,028 B2
• Filed: 09/11/2008
• Issued: 05/04/2010
• Est. Priority Date: 09/03/1999
• Status: Expired due to Fees

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei
• Primary Examiner(s): Roy; Sikha
• Application Number:
  US12/208,528
• Publication Number:
  US 20090051270A1
• Time in Patent Office: 600 Days
• Field of Search: 313/504, 313/506
• US Class Current: 313/506
• 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 27/1251 comprising TFTs having a different architecture, e.g. top- and bottom gate TFTs
• 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 2102/3026 Top emission
• CPC Class Codes: H10K 2102/321 Inverted OLED, i.e. having cathode between substrate and anode
• CPC Class Codes: H10K 50/805 Electrodes
• CPC Class Codes: H10K 50/81 Anodes
• CPC Class Codes: H10K 50/822 characterised by their shape
• CPC Class Codes: H10K 50/826 Multilayers, e.g. opaque multilayers
• CPC Class Codes: H10K 50/854 comprising scattering means
• CPC Class Codes: H10K 50/86 Arrangements for improving contrast, e.g. preventing reflection of ambient light
• CPC Class Codes: H10K 59/12 Active-matrix OLED [AMOLED] displays
• CPC Class Codes: H10K 59/123 Connection of the pixel electrodes to the thin film transistors [TFT]
• CPC Class Codes: H10K 59/17 Passive-matrix OLED displays
• CPC Class Codes: H10K 59/805 Electrodes

Abstract

Reducing the manufacturing cost of an EL display device and an electronic device furnished with the EL display device is taken as an objective. A textured structure in which projecting portions are formed on the surface of a cathode is used. External stray light is diffusely (irregularly) reflected by the action of the projecting portions when reflected by the surface of the cathode, and therefore a defect in which the face of an observer or the surrounding scenery is reflected in the surface of the cathode can be prevented. This can be completed without using a conventionally necessary high price circular polarizing film, and therefore it is possible to reduce the cost of manufacturing the EL display device.

Claims

1. An EL display device comprising:

a switching transistor and a current control transistor formed over a substrate, each of the switching transistor and the current control transistor including an active layer, a gate electrode and a first insulating film between the active layer and the gate electrode;

a first source wiring and a first drain wiring electrically connected to the active layer of the switching transistor;

a second source wiring and a second drain wiring electrically connected to the active layer of the current control transistor;

a second insulating film having a contact hole formed over the switching transistor, the current control transistor, a first source wiring, a first drain wiring, a second source wiring and the second drain wiring;

a first electrode having a plurality of projecting portions formed over the second insulating film and electrically connected to one of the second source wiring and the second drain wiring through the contact hole;

an EL layer formed over the first electrode;

a second electrode formed over the EL layer; and

a third insulating film formed over the second electrode and being in contact with an edge of the second insulating film,

wherein one of the first source wiring and the first drain wiring is electrically connected to the gate electrode of the current control transistor.

2. The EL display device according to claim 1, wherein a spacing between the plurality of projecting portions is in the range of 0.05 to 1 μ

m.

3. The EL display device according to claim 1, wherein each of the second insulating film and the third insulating film is a passivation film.

4. The EL display device according to claim 1, wherein the first electrode comprises a pixel electrode and a cathode.

5. The EL display device according to claim 1, further comprising:

an input-output wiring line formed over the substrate and being electrically connected to the second electrode,

wherein the third insulating film is in contact with the input-output wiring line.

6. An electronic device having the EL display device according to claim 1, wherein the electronic device is one selected from the group consisting of a video camera, a goggle type display, a game machine, a car navigation system, a personal computer, a mobile computer, a portable telephone, an electronic book, an image playback device and an EL display.

7. An EL display device comprising:

a first insulating film formed over a substrate;

a switching transistor and a current control transistor formed the first insulating film, each of the switching transistor and the current control transistor including an active layer, a gate electrode and a second insulating film between the active layer and the gate electrode;

a first source wiring and a first drain wiring electrically connected to the active layer of the switching transistor;

a second source wiring and a second drain wiring electrically connected to the active layer of the current control transistor;

a third insulating film having a contact hole formed over the switching transistor, the current control transistor, a first source wiring, a first drain wiring, a second source wiring and the second drain wiring;

a first electrode having a plurality of projecting portions formed over the second insulating film and electrically connected to one of the second source wiring and the second drain wiring through the contact hole;

an EL layer formed over the first electrode;

a second electrode formed over the EL layer; and

a fourth insulating film formed over the second electrode and being in contact with an edge of the third insulating film,

wherein one of the first source wiring and the first drain wiring is electrically connected to the gate electrode of the current control transistor.

8. The EL display device according to claim 7, wherein a spacing between the plurality of projecting portions is in the range of 0.05 to 1 μ

m.

9. The EL display device according to claim 7, wherein each of the third insulating film and the fourth insulating film is a passivation film.

10. The EL display device according to claim 7, wherein the first electrode comprises a pixel electrode and a cathode.

11. The EL display device according to claim 7, further comprising:

an input-output wiring line formed over the first insulating film and being electrically connected to the second electrode,

wherein the fourth insulating film is in contact with the input-output wiring line.

12. An electronic device having the EL display device according to claim 7, wherein the electronic device is one selected from the group consisting of a video camera, a goggle type display, a game machine, a car navigation system, a personal computer, a mobile computer, a portable telephone, an electronic book, an image playback device and an EL display.

13. An EL display device comprising:

a switching transistor and a current control transistor formed over a substrate, each of the switching transistor and the current control transistor including an active layer, a gate electrode and a first insulating film between the active layer and the gate electrode;

a first source wiring and a first drain wiring electrically connected to the active layer of the switching transistor;

a second source wiring and a second drain wiring electrically connected to the active layer of the current control transistor;

a second insulating film having a first contact hole formed over the switching transistor, the current control transistor, a first source wiring, a first drain wiring, a second source wiring and the second drain wiring;

a third insulating film having a second contact hole and comprising an organic resin formed over the second insulating film;

a first electrode having a plurality of projecting portions formed over the third insulating film and electrically connected to one of the second source wiring and the second drain wiring through the first contact hole and the second contact hole;

an EL layer formed over the first electrode;

a second electrode formed over the EL layer; and

a fourth insulating film formed over the second electrode and being in contact with an edge of the second insulating film and an edge of the third insulating film,

wherein one of the first source wiring and the first drain wiring is electrically connected to the gate electrode of the current control transistor.

14. The EL display device according to claim 13, wherein a spacing between the plurality of projecting portions is in the range of 0.05 to 1 μ

m.

15. The EL display device according to claim 13, wherein each of the second insulating film and the fourth insulating film is a passivation film.

16. The EL display device according to claim 13, wherein the first electrode comprises a pixel electrode and a cathode.

17. The EL display device according to claim 13, further comprising:

an input-output wiring line formed over the substrate and being electrically connected to the second electrode,

wherein the fourth insulating film is in contact with the input-output wiring line.

18. An electronic device having the EL display device according to claim 13, wherein the electronic device is one selected from the group consisting of a video camera, a goggle type display, a game machine, a car navigation system, a personal computer, a mobile computer, a portable telephone, an electronic book, an image playback device and an EL display.