Transflective liquid crystal display and method of fabricating the same

• US 7,480,020 B2
• Filed: 09/16/2004
• Issued: 01/20/2009
• Est. Priority Date: 03/24/2004
• Status: Expired due to Fees

• Current Assignee: InnoLux Corporation
• Original Assignee: TPO Displays Corporation (InnoLux Corporation)
• Inventors: Ting, Dai-Liang, Wen, Chi-Jain, Lin, Gwo-long, Wu, I-Wei, Ho, Shyuan-Jeng
• Primary Examiner(s): Nelms; David
• Assistant Examiner(s): Nguyen; Thanh-Nhan P
• Application Number:
  US10/942,683
• Publication Number:
  US 20050213002A1
• Time in Patent Office: 1,587 Days
• Field of Search: 349/114, 349/113, 349 42- 43, 349 46- 47
• US Class Current: 349/114
• CPC Class Codes: G02F 1/133555 Transflectors
• CPC Class Codes: G02F 1/13439 characterised by their electrical, optical, physical properties; materials therefor; method of making

Abstract

A transflective liquid crystal display and method of fabricating the same. The pixel region of the transflective comprises a thin film transistor, a transmissive electrode, and a reflective electrode, wherein the overlap of the reflective electrode and the transparent electrode composes a reflective region and the non-overlapping region of the reflective electrode and the transparent electrode form a transmissive region, and the transparent electrode and the source and the drain regions of the thin film transistor are formed of the same silicon layer.

Claims

1. A transflective liquid crystal display comprising:

a lower substrate and an upper substrate opposing each other;

a plurality of pixel regions on the lower substrate;

a thin film transistor having a silicon layer;

a transparent electrode formed in the pixel region, wherein the transparent electrode is conductively connected to the thin film transistor; and

a reflective electrode formed over a portion of the transparent electrode, wherein the reflective electrode is conductively connected to the same thin film transistor;

wherein the overlap of the reflective electrode and the transparent electrode forms a reflective region and the non-overlapping region of the reflective electrode and the transparent electrode form a transmissive region; and

the transparent electrode is a conductive silicon layer formed from the same layer as the silicon layer of the thin film transistor.

2. The display as claimed in claim 1, wherein the silicon layer comprises at least one of a polysilicon layer, an amorphous silicon layer, a doped silicon layer, and an un-doped silicon layer.

3. The display as claimed in claim 1, further comprising:

a thin film transistor device comprising a gate electrode, a source and a drain region on the lower substrate;

a first insulating layer, formed on the silicon layer;

a second insulating layer formed on the first insulating layer covering the gate electrode;

a drain electrode, formed on the second insulating layer and overlying the drain region, wherein the drain electrode is an extension of the data line;

a source electrode, formed on the second insulating layer and overlying the source region;

a first contact plug, perforating through the second insulating and first insulating layers to electrically connect the source electrode and the source region; and

an passivation insulating layer, formed on the second insulating layer and overlying the source electrode and the drain electrode;

wherein the first insulating layer, the second insulating layer, and the passivation insulating layer expose the transparent electrode in the transimissive region; and

the reflective electrode is formed on the passivation insulating layer.

4. The display as claimed in claim 3, further comprising:

a second contact plug, perforating through the passivation insulating layer, thereby forming an interconnect between the source electrode and the reflective electrode;

wherein the source region electrically connects the transparent electrode, and the reflective electrode electrically connects the transparent electrode via the second contact plug, the source electrode, the first contact plug, and the source region.

5. The display as claimed in claim 3, further comprising:

an extension of the reflective layer, comformally extended from the sidewall of the passivation insulating layer to the transparent electrode, thereby forming an electrical connection;

wherein the source region connects the transparent electrode, and the source electrode electrically connects the reflective electrode via the first contact plug, the source region, and the transparent electrode.

6. The display as claimed in claim 3, further comprising:

a second contact plug, perforating through the passivation insulating layer, thereby forming an interconnect between the source electrode and the transparent electrode; and

a third contact plug, perforating through the second insulating layer and the passivation insulating layer, thereby forming an interconnect between the source electrode and the transparent electrode;

wherein the source region is separated from the transparent electrode, and the reflective electrode electrically connects the transparent electrode via the second contact plug, the source electrode, and the third contact plug.

7. The display as claimed in claim 3, further comprising:

an extension of the reflective electrode, comformally extended from the sidewall of the passivation insulating layer to the transparent electrode, thereby forming an electrical connection; and

a third contact plug, perforating the second insulating layer and the passivation insulating layer, thereby forming an interconnect between the source electrode and the transparent electrode;

wherein the source region is separated from the transparent electrode, and the reflective electrode electrically connects the transparent electrode via the second contact plug, the source electrode, and the third contact plug.

8. The display as claimed in claim 3, further comprising:

a second contact plug, perforating through the passivation insulating layer, thereby forming an interconnect between the source electrode and the reflective electrode;

an extension of the source electrode, comformally extended from the sidewall of the second insulating layer to the transparent electrode, thereby forming an electrical connection; and

wherein the source region is separated from the transparent electrode, and the reflective electrode electrically connects the transparent electrode via the second contact plug, the source electrode, and the third contact plug.

9. The display as claimed in claim 3, further comprising:

an extension of the source electrode, comformally extended from the sidewall of the second insulating layer to the transparent electrode, thereby forming an electrical connection;

an extension of the reflective electrode, comformally extended from the sidewall of the passivation insulating layer to the transparent electrode, thereby forming an electrical connection; and

wherein the source region is separated from the transparent electrode, and the reflective electrode electrically connects the transparent electrode via the second contact plug, the source electrode, and the third contact plug.

10. The display as claimed in claim 3, further comprising:

a storage electrode, interposed between the first insulating layer and the second insulating layer, and adjacent to the thin film transistor;

wherein the storage electrode is at the same level with the gate electrode, and an overlap of the storage electrode and the transparent electrode forms a capacitor.

11. The display as claimed in claim 1, wherein the transparent electrode of the transmissive region is comb-shaped.

12. The display as claimed in claim 1, wherein the transparent electrode of the transimissive region is a plurality of separated stripes.

13. The display as claimed in claim 1, wherein in the reflective region, the transparent electrode extends between the reflective electrode and the lower substrate.

14. The display as claimed in claim 1, wherein the silicon layer of the thin film transistor and the transparent electrode are at a same layer structure level.

15. A method for fabricating a transflective liquid crystal display, comprising steps of:

providing a substrate, comprising a plurality of pixels with a transmissive region and a reflective region;

forming a silicon layer on the pixels;

forming a first insulating layer on the substrate covering the silicon layer;

forming a first conductive layer on the first insulating layer, and defining the first conductive layer into at least two scan lines and a gate electrode;

forming a thin film transistor comprising a doped silicon layer by the side of the gate electrode, wherein the doped silicon at one side of the gate electrode serves as a drain region, the doped silicon at the other side of the gate electrode serves as a source region, and the doped silicon covering a large portion of the pixels serves as a transparent electrode, and wherein the transparent electrode is conductively connected to the thin film transistor;

forming a second insulating layer on the first insulating layer covering the gate electrode;

forming a first contact plug, perforating through the second insulating layer and the first insulating layer to the source and drain region;

forming a second conductive layer on the second insulating layer, and defining the second conductive layer into at least two data lines, a drain electrode, and a source electrode, wherein the data lines and the scan lines intersect and form a pixel region;

forming a passivation insulating layer on the second insulating layer covering the data lines, the drain electrode, and the source electrode;

removing a portion of the passivation insulating layer, the second insulating layer, and the first insulating layer exposing the transparent electrode; and

forming a reflective electrode on the passivation insulating layer, wherein the reflective electrode is located within the reflective region, and conductively connected to the same thin film transistor.

16. The method as claimed in claim 15, wherein the silicon layer comprises a polysilicon layer or an amorphous layer.

17. The method as claimed in claim 15, further comprising a step of:

forming a second contact plug, perforating through the passivation insulating layer, thereby forming an interconnect between the source electrode and the reflective electrode.

18. The method as claimed in claim 15, further comprising a step of:

forming an extension of the reflective layer comformally extended from the sidewall of the passivation insulating layer to the transparent electrode to serve as an electrical connection.

19. The method as claimed in claim 15, further comprising steps of:

forming a second contact plug perforating through the passivation insulating layer, thereby forming en interconnect between the source electrode and the reflective electrode; and

forming a third contact plug, perforating through the second insulating layer and the first insulating layer, thereby forming an interconnect between the source electrode and the transparent electrode.

20. The method as claimed in claim 15, wherein the source region is separated from the transparent electrode, further comprising:

forming an extension of the reflective electrode, comformally extended from the sidewall of the passivation insulating layer to the transparent electrode, thereby fanning an electrical connection; and

forming a third contact plug, perforating through the second insulating layer and the passivation insulating layer, thereby forming an interconnect between the source electrode and the transparent electrode.

21. The method as claimed in claim 15, wherein the source region is separated from the transparent electrode, further comprising steps of:

forming a second contact plug, perforating through the passivation insulating layer, thereby forming an interconnect between the source electrode and the reflective electrode; and

forming an extension of the source electrode, comformally extended from the sidewall of the second insulating layer to the transparent electrode, thereby forming an electrical connection.

22. The method as claimed in claim 15, wherein the source region is separated from the transparent electrode, further comprising steps of:

forming an extension of the source electrode, comformally extended from the sidewall of the second insulating layer to the transparent electrode, thereby forming an electrical connection; and

forming an extension of the reflective electrode, comformally extended from the sidewall of the passivation insulating layer to the transparent electrode, thereby forming electrical connection.