Switching element, display device, light emitting device using the switching element, and semiconductor device

• US 20030066740A1
• Filed: 10/09/2002
• Published: 04/10/2003
• Est. Priority Date: 10/09/2001
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Inukai, Kazutaka
• Granted Patent: US 7,102,161 B2
• Time in Patent Office: Days
• US Class Current: 200/11D
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2300/0861 with additional control of the display period without amending the charge stored in a pixel memory, e.g. by means of additional select electrodes
• CPC Class Codes: G09G 2310/0248 Precharge or discharge of column electrodes before or after applying exact column voltages
• CPC Class Codes: G09G 3/325 the data current flowing through the driving transistor during a setting phase, e.g. by using a switch for connecting the driving transistor to the data driver
• CPC Class Codes: G09G 3/3283 in which the data driver supplies a variable data current for setting the current through, or the voltage across, the light-emitting elements
• CPC Class Codes: H10K 59/12 Active-matrix OLED [AMOLED] displays

Abstract

A switching element is provided, which is capable of short-circuiting or opening three or more nodes simultaneously, and in which the surface area occupied on a substrate can be reduced. The switching element of the present invention has an active layer, an insulating film contacting the active layer, a gate electrode contacting the insulating film, and three or more connection electrodes. The active layer has at least one channel forming region and three or more impurity doped regions, and the connection electrodes are each connected to a different impurity region. An impurity region contacting an arbitrary connection electrode contacts only one of the channel forming regions.

Claims

1. A switching element comprising:

an insulating surface;

an active layer contacting the insulating surface;

a gate insulating film formed on the insulating surface and covering the active layer; and

a gate electrode contacting the gate insulating film;

wherein;

the active layer has a channel forming region and three or more impurity regions;

the channel forming region and the gate electrode overlap with each other while sandwiching the gate insulating film therebetween;

the three or more impurity regions are each connected to at least one wiring; and

the three or more impurity regions contact the channel forming region.

2. A display device having the switching element according to claim 1.

3. A switching element comprising:

an insulating surface;

an active layer contacting the insulating surface;

a gate insulating film formed on the insulating surface and covering the active layer; and

a gate electrode contacting the gate insulating film;

wherein;

the active layer has a channel forming region and three or more impurity regions;

the channel forming region and the gate electrode overlap with each other while sandwiching the gate insulating film therebetween;

the three or more impurity regions are each connected to at least one wiring; and

each of the three or more impurity regions connects each of low concentration impurity regions, and all the low concentration impurity regions connect the channel forming region.

4. A display device having the switching element according to claim 3.

5. A switching element comprising:

an insulating surface;

an active layer contacting the insulating surface;

a gate insulating film formed on the insulating surface and covering the active layer; and

a gate electrode contacting the gate insulating film;

wherein;

the active layer has a channel forming region and three or more impurity regions;

the channel forming region and the gate electrode overlap with each other while sandwiching the gate insulating film therebetween;

the three or more impurity regions are each connected to at least one wiring; and

each of the three or more impurity regions connects each of the offset regions, and all the offset regions connect the channel forming region.

6. A display device having the switching element according to claim 5.

7. A switching element comprising:

an insulating surface;

an active layer contacting the insulating surface;

a gate insulating film formed on the insulating surface and covering the active layer; and

n gate electrodes (where n is a natural number equal to or greater than

     2) contacting the gate insulating film;

wherein;

the active layer has n channel forming regions and three or more impurity regions;

each of the n channel forming regions and each of the n gate electrodes overlap with each other while sandwiching the gate insulating film therebetween;

each of the three or more impurity regions is connected to at least one wiring; and

each of the three or more impurity regions contacts one mutually different channel forming region from among the n channel forming regions.

8. A display device having the switching element according to claim 7.

9. A switching element comprising:

an insulating surface;

an active layer contacting the insulating surface;

a gate insulating film formed on the insulating surface and covering the active layer; and

n gate electrodes (where n is a natural number equal to or greater than

     2) contacting the gate insulating film;

wherein;

the active layer has n channel forming regions and three or more impurity regions;

each of the n channel forming regions and each of the n gate electrodes overlap with each other while sandwiching the gate insulating film therebetween;

each of the three or more impurity regions is connected to at least one wiring; and

each of the three or more impurity regions contacts each of low concentration impurity regions, respectively, and the low concentration impurity regions contact one mutually different channel forming region from among the n channel forming regions.

10. A display device having the switching element according to claim 9.

11. A switching element comprising:

an insulating surface;

an active layer contacting the insulating surface;

a gate insulating film formed on the insulating surface and covering the active layer; and

n gate electrodes (where n is a natural number equal to or greater than

     2) contacting the gate insulating film;

wherein;

the active layer has n channel forming regions and three or more impurity regions;

each of the n channel forming regions and each of the n gate electrodes overlap with each other while sandwiching the gate insulating film therebetween;

each of the three or more impurity regions is connected to at least one wiring; and

each of the three or more impurity regions contacts each of offset regions, and all the offset regions contact one mutually different channel forming region from among the n channel forming regions.

12. A display device having the switching element according to claim 11.

13. A switching element comprising:

an insulating surface;

a gate electrode contacting the insulating surface;

a gate insulating film formed on the insulating surface and covering the gate electrode; and

an active layer contacting the gate insulating film;

wherein;

the active layer has a channel forming region and three or more impurity regions;

the channel forming region and the gate electrode overlap with each other while sandwiching the gate insulating film therebetween;

the three or more impurity regions are each connected to at least one wiring; and

the three or more impurity regions are connected to the channel forming region.

14. A display device having the switching element according to claim 13.

15. A switching element comprising:

n gate electrodes (where n is a natural number equal to or greater than

     2) contacting the insulating surface;

a gate insulating film formed on the insulating surface covering n gate electrodes; and

an active layer contacting the gate insulating film;

wherein;

the active layer has n channel forming regions and three or more impurity regions;

each of the n channel forming regions and n gate electrodes overlap with each other while sandwiching the gate insulating film;

each of the three or more impurity regions is connected to at least one wiring; and

each of the three or more impurity regions contacts one mutually different channel forming region from among the n channel forming regions.

16. A display device having the switching element according to claim 15.

17. A light emitting device comprising:

a switching element;

a first transistor;

a second transistor;

an organic light emitting element;

a signal line; and

an electric power source line;

wherein;

the switching element has;

an active layer;

a gate insulating film contacting the active layer; and

a gate electrode contacting the gate insulating film;

the active layer has a channel forming region and three impurity regions;

the channel forming region and the gate electrode overlap with each other while sandwiching the gate insulating film therebetween;

the three impurity regions contact the channel forming region;

the first transistor has a gate electrode, a drain region, and a source region;

among the three impurity regions;

one impurity region is connected to the signal line;

one impurity region is connected to the gate electrode of the first transistor; and

one impurity region is connected to the drain region of the first transistor;

the second transistor has a source region and a drain region;

one of the source region and the drain region of the second transistor is connected to the electric power source line, and the other is connected to the drain region of the first transistor;

the organic light emitting element has a pixel electrode; and

the source region of the first transistor is connected to the pixel electrode of the organic light emitting element.

20. The semiconductor device according to claim 17 further comprising a first electrode electrically connected to a first one of the three impurity regions, a second electrode electrically connected to a second one of the three impurity regions, and a third electrode electrically connected to a third one of the three impurity regions.

18. A light emitting device comprising:

a switching element;

a first transistor;

a second transistor;

an organic light emitting element;

a signal line;

an electric power source line;

a first scanning line; and

a second scanning line, wherein;

the switching element has;

an active layer;

a gate insulating film contacting the active layer; and

a gate electrode contacting the gate insulating film;

the active layer has a channel forming region and three impurity regions;

the channel forming region and the gate electrode overlap with each other while sandwiching the gate insulating film therebetween;

the three impurity regions contact the channel forming region;

the first transistor has a gate electrode, a drain region, and a source region;

among the three impurity regions;

one impurity region is connected to the signal line;

one impurity region is connected to a gate electrode of the first transistor; and

one impurity region is connected to a drain region of the first transistor;

the gate electrode of the switching element is connected to the first scanning line;

the gate electrode of the second transistor is connected to the second scanning line;

the second transistor has a source region and a drain region;

the source region or the drain region of the second transistor is connected to the electric power source line, and the other is connected to the drain region of the first transistor;

the organic light emitting element has a pixel electrode; and

the source region of the first transistor is connected to the pixel electrode of the organic light emitting element.

19. A semiconductor device comprising:

an insulating surface;

a semiconductor island formed on the insulating surface, said semiconductor island comprising a channel forming region and at least three impurity regions, wherein each of said at least three impurity regions is separated from one another and is in contact with said channel region;

a gate insulating film formed on said semiconductor island; and

a gate electrode formed over the channel region with the gate insulating film interposed therebetween.