EL display device, driving method thereof, and electronic equipment provided with the EL display device

• US 8,558,773 B2
• Filed: 02/26/2013
• Issued: 10/15/2013
• Est. Priority Date: 06/21/1999
• Status: Expired due to Fees

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamauchi, Yukio, Fukunaga, Takeshi
• Primary Examiner(s): Vo, Tuyet Thi
• Application Number:
  US13/776,772
• Publication Number:
  US 20130175536A1
• Time in Patent Office: 231 Days
• Field of Search: 345/92, 345/90, 345/88, 345/82, 345/76, 345/100, 345/77, 345/102
• US Class Current: 345/92
• CPC Class Codes: G09G 2300/023 Display panel composed of stacked panels
• CPC Class Codes: G09G 2300/04 Structural and physical details of display devices
• CPC Class Codes: G09G 2300/0408 Integration of the drivers onto the display substrate
• CPC Class Codes: G09G 2300/0417 Special arrangements specific to the use of low carrier mobility technology
• CPC Class Codes: G09G 2300/0426 Layout of electrodes and connections
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 3/2018 by time modulation using two or more time intervals
• CPC Class Codes: G09G 3/2022 using sub-frames
• CPC Class Codes: G09G 3/30 using electroluminescent panels
• CPC Class Codes: G09G 3/32 semiconductive, e.g. using light-emitting diodes [LED]
• CPC Class Codes: G09G 3/3225 using an active matrix
• CPC Class Codes: G09G 3/3258 with pixel circuitry controlling the voltage across the light-emitting element
• CPC Class Codes: H01L 27/1277 using a crystallisation promoting species, e.g. local introduction of Ni catalyst
• CPC Class Codes: H01L 27/1296 adapted to increase the uniformity of device parameters
• CPC Class Codes: H01L 27/156 two-dimensional arrays
• CPC Class Codes: H01L 29/045 by their particular orientation of crystalline planes
• CPC Class Codes: H01L 29/0603 characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions isolation regions between components H01L21/76; design considerations for integrated circuits H01L27/00; geometrical design considerations for devices H01L29/0657
• CPC Class Codes: H01L 29/786 Thin film transistors, i.e. transistors with a channel being at least partly a thin film transistors having only the source or the drain region on an insulator layer H01L29/0653; thin film FinFETs H01L29/785
• 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 29/78624 the source and the drain regions being asymmetrical
• 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 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 33/62 : Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls
• CPC Class Codes: H10K 2102/3026 : Top emission
• 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 59/122 : Pixel-defining structures or layers, e.g. banks
• CPC Class Codes: H10K 59/8794 : Arrangements for heating and cooling

Abstract

An EL display device capable of performing clear multi-gradation color display and electronic equipment provided with the EL display device are provided, wherein gradation display is performed according to a time-division driving method in which the luminescence and non-luminescence of an EL element (109) disposed in a pixel (104) are controlled by time, and the influence by the characteristic variability of a current controlling TFT (108) is prevented. When this method is used, a data signal side driving circuit (102) and a gate signal side driving circuit (103) are formed with TFTs that use a silicon film having a peculiar crystal structure and exhibit an extremely high operation speed.

Claims

1. A display device comprising:

a first glass substrate;

a base insulating film over and in contact with the first glass substrate, the base insulating film comprising silicon;

a semiconductor film over the base insulating film, the semiconductor film comprising polysilicon;

a gate insulating film over the semiconductor film, the gate insulating film comprising a first insulating film containing silicon and oxygen and a second insulating film containing silicon and nitrogen;

a gate electrode over the gate insulating film, the gate electrode comprising molybdenum;

a third insulating film over the gate electrode, the third insulating film being a stack comprising silicon-containing films each selected from a silicon oxide film, a silicon nitride film, and a silicon nitride oxide film;

a source electrode and a drain electrode over the third insulating film, the source electrode and the drain electrode each comprising a first titanium film, an aluminum film over the first titanium film, and a second titanium film over the aluminum film;

a fourth insulating film over the source electrode and the drain electrode, the fourth insulating film comprising an organic resin;

a pixel electrode over the fourth insulating film, the pixel electrode comprising a metal and being electrically connected to one of the source electrode and the drain electrode;

a fifth insulating film over the fourth insulating film and having an opening in which the pixel electrode is exposed, wherein the fifth insulating film comprises an organic resin, covers an edge of the pixel electrode, and has a tapered shape in a region surrounding the opening;

an EL layer over the pixel electrode and the fifth insulating film; and

a conductive film over the EL layer, the conductive film being capable of transmitting light emitted from the EL layer.

2. A portable telephone comprising the display device according to claim 1.

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

a second glass substrate over the conductive film,

wherein the second glass substrate is fixed to the first glass substrate by an adhesive to form a closed space, and

wherein an area of the second glass substrate is smaller than an area of the first glass substrate so that a part of the first glass substrate is exposed.

4. The display device according to claim 3, further comprising a gate signal side driving circuit,

wherein at least part of the gate signal side driving circuit is located in the closed space.

5. The display device according to claim 3, further comprising a flexible print circuit which is connected to the display device in a region where the first glass substrate is exposed due to the difference in area between the first glass substrate and the second glass substrate.

6. A display device comprising:

a pixel portion over a first glass substrate;

a pair of gate signal side driver circuits over the first glass substrate, the pair of gate signal side driver circuits interposing the pixel portion; and

a second glass substrate over the pixel portion and the pair of gate signal side driver circuits,

wherein the pixel portion comprises a set of a blue-emissive pixel, a green-emissive pixel, and a red-emissive pixel,

wherein the blue-emissive pixel, the green-emissive pixel, and the red-emissive pixel each comprise;

a base insulating film over and in contact with the first glass substrate, the base insulating film comprising silicon;

a semiconductor film over the base insulating film, the semiconductor film comprising polysilicon;

a gate insulating film over the semiconductor film, the gate insulating film comprising a first insulating film containing silicon and oxygen and a second insulating film containing silicon and nitrogen;

a gate electrode over the gate insulating film, the gate electrode comprising molybdenum;

a third insulating film over the gate electrode, the third insulating film being a stack comprising silicon-containing films each selected from a silicon oxide film, a silicon nitride film, and a silicon nitride oxide film;

a source electrode and a drain electrode over the third insulating film, the source electrode and the drain electrode each comprising a first titanium film, an aluminum film over the first titanium film, and a second titanium film over the aluminum film;

a fourth insulating film over the source electrode and the drain electrode, the fourth insulating film comprising an organic resin;

a pixel electrode over the fourth insulating film, the pixel electrode comprising a metal and being electrically connected to one of the source electrode and the drain electrode;

a fifth insulating film over the fourth insulating film and having an opening in which the pixel electrode is exposed, wherein the fifth insulating film comprises an organic resin, covers an edge of the pixel electrode, and has a tapered shape in a region surrounding the opening;

an EL layer over the pixel electrode and the fifth insulating film, the EL layer being arranged to emit respective emission color; and

a conductive film over the EL layer, the conductive film being capable of transmitting light emitted from the EL layer.

7. The display device according to claim 6,

wherein the second glass substrate is fixed to the first glass substrate by an adhesive to form a closed space, and

wherein the pixel portion and at least part of the pair of gate signal side driver circuits are located in the closed space.

8. A portable telephone comprising the display device according to claim 6.

9. The display device according to claim 6,

wherein an area of the second glass substrate is smaller than an area of the first glass substrate so that a part of the first glass substrate is exposed.

10. The display device according to claim 9, further comprising a flexible print circuit which is connected to the display device in a region where the first glass substrate is exposed due to the difference in area between the first glass substrate and the second glass substrate.

11. A display device comprising:

a pixel portion over a first glass substrate, the pixel portion comprising a plurality of pixels;

a second glass substrate over the pixel portion, wherein an area of the second glass substrate is smaller than an area of the first glass substrate so that a part of the first glass substrate is exposed; and

a flexible print circuit over the first glass substrate,

wherein at least one of the plurality of pixels comprising;

a base insulating film over and in contact with the first glass substrate, the base insulating film comprising silicon;

a semiconductor film over the base insulating film, the semiconductor film comprising polysilicon;

a gate insulating film over the semiconductor film, the gate insulating film comprising a first insulating film containing silicon and oxygen and a second insulating film containing silicon and nitrogen;

a gate electrode over the gate insulating film, the gate electrode comprising molybdenum;

a third insulating film over the gate electrode, the third insulating film being a stack comprising silicon-containing films each selected from a silicon oxide film, a silicon nitride film, and a silicon nitride oxide film;

a wiring over the third insulating film, the wiring being configured to function as a source electrode and a drain electrode and comprising a first titanium film, an aluminum film over the first titanium film, and a second titanium film over the aluminum film;

a fourth insulating film over the wiring, the fourth insulating film comprising an organic resin;

a pixel electrode over the fourth insulating film, the pixel electrode comprising a metal and being electrically connected to the wiring;

a fifth insulating film over the fourth insulating film and having an opening in which the pixel electrode is exposed, wherein the fifth insulating film comprises an organic resin, covers an edge of the pixel electrode, and has a tapered shape in a region surrounding the opening;

an EL layer over the pixel electrode and the fifth insulating film; and

a conductive film over the EL layer, the conductive film being capable of transmitting light emitted from the EL layer, and

wherein the flexible print circuit is electrically connected to the wiring over the exposed part of the first glass substrate.

12. A portable telephone comprising the display device according to claim 11.

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

a pair of gate signal side driver circuits over the first glass substrate,

wherein the pixel portion is interposed between the pair of gate signal side driver circuits.

14. The display device according to claim 13,

wherein the second glass substrate is fixed to the first glass substrate by an adhesive to form a closed space, and

wherein at least part of the pair of gate signal side driver circuits is located in the closed space.