EL display device and manufacturing method thereof

• US 6,433,487 B1
• Filed: 08/23/2000
• Issued: 08/13/2002
• Est. Priority Date: 09/03/1999
• Status: Expired due to Term

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei
• Primary Examiner(s): Wong, Don
• Assistant Examiner(s): VO, TUYET THI
• Application Number:
  US09/644,429
• Time in Patent Office: 720 Days
• Field of Search: 315/169.3, 315/169.1, 313/506, 313/504, 313/507, 313/111, 313/113, 313/116, 136/261
• US Class Current: 315/169.3
• 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 electroluminescence display device comprising:

a plurality of cathodes formed in a stripe shape;

an electroluminescence layer formed over the plurality of cathodes; and

a plurality of anodes formed in a stripe shape over the electroluminescence layer;

wherein the plurality of cathodes and the plurality of anodes are arranged so as to be orthogonal to each other;

wherein the surfaces of the plurality of cathodes on the sides closer to the electroluminescence layer have textured structures, each of said textured structures comprising projecting portions, and

wherein a pitch between said projecting portions to 0.05 to 1 μ

m.

2. A device according to claim 1, wherein the cathode is formed on an electrode having a textured structure on its surface.

3. A device according to claim 1 wherein the electroluminescence display device is incorporated into a device selected from the group consisting of a video camera, a digital camera, a goggle type display, a game machine, a car navigation system, a personal computer, a portable information terminal, a mobile computer, a portable telephone, an electronic book and an image playback device.

4. An electroluminescence display device comprising an electroluminescence element containing a cathode, an electroluminescence layer, and an anode, wherein the surface of the cathode on the side closer to the electroluminescence layer has a textured structure comprising projection portions, and wherein a pitch between said projecting portions is 0.05 to 1 μ

m.

5. A device according to claim 4, wherein the cathode is formed on an electrode having a textured structure on its surface.

6. A device according to claim 4 wherein the electroluminescence display device is incorporated into a device selected from the group consisting of a video camera, a digital camera, a goggle type display, a game machine, a car navigation system, a personal computer, a portable information terminal, a mobile computer, a portable telephone, an electronic book and an image playback device.

7. An electroluminescence display device comprising an electroluminescence element containing a cathode, an electroluminescence layer, and an anode,

wherein the electroluminescence element is electrically connected to a thin film resistor,

wherein the surface of the cathode on the side closer to the electroluminescence layer has a textured structure comprising projecting portions, and

wherein a pitch between said projecting portions is 0.05 to 1 μ

m.

8. A device according to claim 7, wherein the cathode is formed on an electrode having a textured structure on its surface.

9. A device according to claim 7 wherein the electroluminescence display device is incorporated into a device selected from the group consisting of a video camera, a digital camera, a goggle type display, a game machine, a car navigation system, a personal computer, a portable information terminal, a mobile computer, a portable telephone, an electronic book and an image playback device.

10. A method of manufacturing an electroluminescence display device, comprising:

a step of forming a first textured structure on a surface of an electrode;

a step of forming a cathode over the electrode having the first textured structure to form a second textured structure comprising projecting portions on a surface of said cathode;

a step of forming an electroluminescence layer over the cathode; and

a step of forming an anode over the electroluminescence layer,

wherein a pitch between said projecting portions of said second textured structure is 0.05 to 1 μ

m.

11. A method according to claim 10, wherein the step of forming the textured structure is performed by photolithography.

12. A method according to claim 10, wherein the step of forming the textured structure is performed by holography.

13. A method according to claim 10 wherein the electroluminescence display device is incorporated into a device selected from the group consisting of a video camera, a digital camera, a goggle type display, a game machine, a car navigation system, a personal computer, a portable information terminal, a mobile computer, a portable telephone, an electronic book and an image playback device.

14. A method of manufacturing an electroluminescence display device, comprising:

a step of forming a plurality of electrodes arranged in a stripe shape;

a step of forming first textured structures on the plurality of electrodes;

a step of forming a cathode over the plurality of electrodes on which the first textured structures are formed to form a second textured structure comprising projecting portions on a surface of said cathode;

a step of forming an electroluminescence layer over the cathode; and

a step of forming a plurality of anodes arranged in a stripe shape over the electroluminescence layer so as to be orthogonal to the plurality of electrodes arranged in the stripe shape,

wherein a pitch between said projecting portions of said second textured structure is 0.05 to 1 μ

m.

15. A method according to claim 14, wherein the step of forming the textured structure is performed by photolithography.

16. A method according to claim 14, wherein the step of forming the textured structure is performed by holography.

17. A method according to claim 14 wherein the electroluminescence display device is incorporated into a device selected from the group consisting of a video camera, a digital camera, a goggle type display, a game machine, a car navigation system, a personal computer, a portable information terminal, a mobile computer, a portable telephone, an electronic book and an image playback device.

18. A method of manufacturing an electroluminescence display device, comprising:

a step of forming a thin film transistor;

a step of forming a pixel electrode electrically connected to the thin film transistor;

a step of forming a first textured structure on a surface of the pixel electrode;

a step of forming a cathode over the pixel electrode on which the first textured structure is formed to form a second textured structure comprising projecting portions on a surface of said cathode;

a step of forming an electroluminescence layer over the cathode; and

a step of forming an anode over the electroluminescence layer,

wherein a pitch between said projecting portions of said second textured structure is 0.05 to 1 μ

m.

19. A method according to claim 18, wherein the step of forming the textured structure is performed by photolithography.

20. A method according to claim 18, wherein the step of forming the textured structure is performed by holography.

21. A method according to claim 18 wherein the electroluminescence display device is incorporated into a device selected from the group consisting of a video camera, a digital camera, a goggle type display, a game machine, a car navigation system, a personal computer, a portable information terminal, a mobile computer, a portable telephone, an electronic book and an image playback device.