Electro-optical device

• US 7,012,656 B2
• Filed: 03/16/2001
• Issued: 03/14/2006
• Est. Priority Date: 03/17/2000
• Status: Expired due to Term

• Current Assignee: 138 East LCD Advancements Limited (Vector Capital Corporation)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Murade, Masao
• Primary Examiner(s): Parker, Kenneth
• Application Number:
  US09/809,207
• Publication Number:
  US 20020021378A1
• Time in Patent Office: 1,824 Days
• Field of Search: 349/38, 349/34, 349/42, 349/43, 349/110, 349/44
• US Class Current: 349/43
• CPC Class Codes: G02F 1/136213 Storage capacitors associated with the pixel electrode
• CPC Class Codes: G02F 1/136227 Through-hole connection of the pixel electrode to the active element through an insulation layer
• CPC Class Codes: G02F 1/1368 in which the switching element is a three-electrode device G02F1/136277 takes precedence

Abstract

An electro-optical device includes a substrate on which a TFT, a data line, a scanning line, a capacitance line, a first intermediate conductive layer, a second intermediate conductive layer, and a pixel electrode are formed. A first contact hole, via which the drain of the TFT and the first intermediate conductive layer are connected to each other, is formed in an area which overlaps, in plan view, with the data line. The above-described structure of this electro-optical device, which includes the intermediate conductive layer disposed between the pixel electrode and the pixel switching TFT, allows an increase in the pixel aperture ratio and also an increase in the storage capacitance. Besides, degradation in the quality of a displayed image due to steps formed, in the vicinity of the pixel electrode, on the surface of an alignment film is minimized.

Claims

1. An electro-optical device comprising:

a thin film transistor formed above a substrate;

a pixel electrode electrically connected to a drain region of a semiconductor layer of said thin film transistor;

a storage capacitor having a first capacitor electrode which comprises said drain region and a second capacitor electrode;

an intermediate conductive layer for electrically connecting said drain region of said semiconductor layer of said thin film transistor and said pixel electrode, said intermediate conductive layer disposed between a layer of said second capacitor and a layer of said pixel electrode; and

an upper conductive layer disposed between a layer of said intermediate conductive layer and said layer of said pixel electrode; and

a first contact hole formed in an area under upper conductive layer, said first contact hole serving to electrically connect to said drain region of said semiconductor layer of said thin film transistor to said intermediate conductive layer.

2. The electro-optical device according to claim 1, at least one of said plurality of upper conductive layers serving as a capacitance line which extends under said intermediate conductive layer while avoiding an area where said first contact hole is formed.

3. The electro-optical device according to claim 1, said first contact hole having a depth that is smaller than a depth of a second contact hole formed between said intermediate conductive layer and said pixel electrode.

4. The electro-optical device according to claim 1, said intermediate conductive layer includes a light-shielding conductive film.

5. The electro-optical device according to claim 4, said intermediate conductive layer comprising a part of a light-shielding area.

6. The electro-optical device according to claim 5, said intermediate conductive layer comprising a part extending along said data line in plan view, and said part defining a part of said light-shielding area along said data line.

7. The electro-optical device according to claim 6, further comprising capacitor electrode which includes a part extending along said data line in plan view, and

in an area along said data line, a width Wd of said data line, a width We of said capacitor electrode, and a width Wm of the part, extending along said data line, of said intermediate conductive layer are selected so as to satisfy a condition Wd<

Wc<

Wm.

8. The electro-optical device according to claim 7, an edge portion, extending along said data line, of said pixel electrode overlapping with an edge portion of aid intermediate conductive layer.

9. An electro-optical device, comprising:

a thin film transistor formed above a substrate;

a pixel electrode electrically connected to a drain region of a semiconductor layer of said thin film transistor;

a plurality of upper conductive layers disposed between a layer of said semiconductor layer of said thin film transistor and a layer of said pixel electrode;

an intermediate conductive layer that electrically connects said drain region of said semiconductor layer of said thin film transistor and said pixel electrode; and

a first contact hole formed in an area under at least one of said plurality of upper conductive layers, said first contact hole electrically connecting said drain region of said semiconductor layer of said thin film transistor to said intermediate conductive layer,

said first contact hole having a diameter that is smaller than a diameter of a second contact hole that electrically connects said intermediate conductive layer to said pixel electrode.

10. An electro-optical device, comprising:

a thin film transistor formed above a substrate;

a pixel electrode electrically connected to a drain region of a semiconductor layer of said thin film transistor;

a plurality of upper conductive layers disposed between a layer of said semiconductor layer of said thin film transistor and a layer of said pixel electrode;

an intermediate conductive layer that electrically connects said drain region of said semiconductor layer of said thin film transistor and said pixel electrode; and

a first contact hole formed in an area under at least one of said plurality of upper conductive layers, said first contact hole electrically connecting said drain region of said semiconductor layer of said thin film transistor to said intermediate conductive layer,

at least one of said plurality of upper conductive layers serving as a data line electrically connected to a source region of said semiconductor layer of said thin film transistor, and said first contact hole being located in an area under said data line.

11. The electro-optical device according to claim 10, said first contact hole being disposed near a location where said line and said scanning line cross each other.

12. The electro-optical device according to claim 10, least one of said plurality of upper conductive layers serving as a scanning line extending in a direction crossing said data line, and said intermediate conductive layer extending along said scanning line from an area of said data line.

13. The electro-optical device according to claim 11, further comprising a second contact hole, via which said intermediate conductive layer and said pixel electrode are electrically connected to each other, is formed in an area where said intermediate conductive layer extends along said scanning line.

14. The electro-optical device according to claim 13, said second contact hole being formed at a substantially middle location between adjacent data lines.

15. The electro-optical device according to claim 11, said intermediate conductive layer being disposed at least partially opposite to a capacitor electrode formed of a film forming said scanning line via an interlayer insulating film.

16. The electro-optical device according to claim 15, further comprising a second contact hole formed at a location which overlaps, in plan view, with said capacitor electrode.

17. The electro-optical device according to claim 15,

said capacitor electrode comprising a part extending along said scanning line and a part extending along said data line from a location where said capacitor electrode and said data line cross each other, in plan view, and

said intermediate conductive layer overlapping, at least partially, with said capacitance electrode via an interlayer insulating film.

18. The electro-optical device according to claim 10, said intermediate conductive layer extending along said data line.

19. The electro-optical device according to claim 10, said semiconductor layer being formed in an area under said data line.

20. The electro-optical device according to claim 19, said first contact hole being formed at a location symmetrical to the location of a third contact hole via which the source region of said semiconductor layer and said data line are connected to each other, with respect to a channel region of said semiconductor layer.

21. The electro-optical device according to claim 19, further comprising:

a lower light shielding film which is disposed under said semiconductor layer which projects, in plan view, from said scanning line, and

a second contact hole via which said intermediate conductive layer and said pixel electrode are electrically connected to each other, the second contact hole being located in an area into which said lower light shielding film projects, in plan view, from said scanning line.

22. An electro-optical device comprising:

a thin film transistor formed on a substrate;

a data line electrically connected to a drain region of a semiconductor layer of said thin film transistor;

a pixel electrode electrically connected to a drain region of said semiconductor layer of said thin film transistor;

a light-shielding intermediate conductive layer that electrically connects the drain region of said semiconductor layer of said thin film transistor and said pixel electrode;

a capacitance line which is disposed in the drain region of said semiconductor layer of said thin film transistor and which extends along said data line;

a light-shielding film formed of a film forming said intermediate conductive layer; and

a contact hole via which said capacitance line and said light shielding film are electrically connected with each other in an area under said data line.