Semiconductor device and liquid crystal display device

• US 8,854,583 B2
• Filed: 03/30/2011
• Issued: 10/07/2014
• Est. Priority Date: 04/12/2010
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Kubota, Daisuke, Yamashita, Akio, Ishitani, Tetsuji, Tamura, Tomohiro, Mikami, Mayumi
• Primary Examiner(s): Briggs, Nathanael R
• Application Number:
  US13/075,292
• Publication Number:
  US 20110249228A1
• Time in Patent Office: 1,287 Days
• Field of Search: 349/42, 349/43, 349/140, 349/141, 349/122, 349/138
• US Class Current: 349/138
• CPC Class Codes: G02F 1/1334 based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
• CPC Class Codes: G02F 1/1343 Electrodes reflective electrodes G02F1/133553
• CPC Class Codes: G02F 1/13439 characterised by their electrical, optical, physical properties; materials therefor; method of making
• CPC Class Codes: G02F 1/13793 Blue phases
• CPC Class Codes: G02F 1/139 based on orientation effects in which the liquid crystal remains transparent
• CPC Class Codes: H01L 27/1225 with semiconductor materials not belonging to the group IV of the periodic table, e.g. InGaZnO

Abstract

In a liquid crystal display device in which a liquid crystal layer exhibiting a blue phase is sandwiched between a first substrate and a second substrate, a pixel electrode layer is electrically connected to a drain electrode layer of a transistor and a common electrode layer is electrically connected to a conductive layer formed through the same steps as the drain electrode layer. The pixel electrode layer and the common electrode layer are over an interlayer film and spaced apart from each other. An opening formed in the interlayer film is filled with liquid crystal, and the liquid crystal layer is formed.

Claims

1. A liquid crystal display device comprising:

a substrate;

a transistor comprising a gate insulating layer, a semiconductor layer, and a source electrode and a drain electrode electrically connected to the semiconductor layer, over the substrate;

a conductive layer over the substrate;

an interlayer insulating film over the transistor and the conductive layer;

a first electrode layer electrically connected to one of the source electrode and the drain electrode, the first electrode layer being on and in contact with the interlayer insulating film;

a second electrode layer electrically connected to the conductive layer, the second electrode layer being on and in contact with the interlayer insulating film; and

a liquid crystal layer including a liquid crystal material exhibiting a blue phase,

wherein the one of the source electrode and the drain electrode, the interlayer insulating film, and the first electrode layer are stacked,

wherein the conductive layer, the interlayer insulating film, and the second electrode layer are stacked,

wherein the one of the source electrode and the drain electrode and the conductive layer are spaced apart from each other,

wherein the interlayer insulating film and the gate insulating layer have an opening between the first electrode layer and the second electrode layer,

wherein the liquid crystal layer is included in the opening,

wherein the substrate and side surfaces of the gate insulating layer, the one of the source electrode and the drain electrode, the interlayer insulating film, the first electrode layer, the conductive layer, and the second electrode layer are exposed in the opening, and

wherein the substrate and the side surfaces of the gate insulating layer, the one of the source electrode and the drain electrode, the interlayer insulating film, the first electrode layer, the conductive layer, and the second electrode layer are in contact with the liquid crystal layer.

2. The liquid crystal display device according to claim 1,

wherein the first electrode layer and the second electrode layer each have a comb-like shape.

3. The liquid crystal display device according to claim 1, further comprising a second insulating layer on and in contact with the one of the source electrode and the drain electrode and the conductive layer,

wherein the second insulating layer is interposed between the transistor and the interlayer insulating film.

4. The liquid crystal display device according to claim 1,

wherein the liquid crystal layer includes a photocurable resin and a photopolymerization initiator.

9. The liquid crystal display device according to claim 1,

wherein the second electrode layer and the third electrode layer have substantially the same pattern in a plan view.

10. The liquid crystal display device according to claim 1,

wherein the semiconductor layer comprises an oxide semiconductor layer, and

wherein the oxide semiconductor layer comprises a crystal region which is c-axis-aligned perpendicularly to a surface of the oxide semiconductor layer.

5. A liquid crystal display device comprising:

a first substrate;

a transistor comprising a gate insulating layer, a semiconductor layer, and a source electrode and a drain electrode electrically connected to the semiconductor layer, over the first substrate;

a conductive layer over the first substrate;

an interlayer insulating film over the transistor and the conductive layer;

a first electrode layer electrically connected to one of the source electrode and the drain electrode, the first electrode layer being on and in contact with the interlayer insulating film;

a second electrode layer electrically connected to the conductive layer, the second electrode layer being on and in contact with the interlayer insulating film; and

a liquid crystal layer including a liquid crystal material exhibiting a blue phase, over the first electrode layer and the second electrode layer;

a third electrode layer overlapping with the second electrode layer, over the liquid crystal layer; and

a second substrate over the third electrode layer,

wherein the one of the source electrode and the drain electrode, the interlayer insulating film, and the first electrode layer are stacked,

wherein the conductive layer, the interlayer insulating film, and the second electrode layer are stacked,

wherein the one of the source electrode and the drain electrode and the conductive layer are spaced apart from each other,

wherein the interlayer insulating film and the gate insulating layer have an opening between the first electrode layer and the second electrode layer,

wherein the liquid crystal layer is included in the opening,

wherein the first substrate and side surfaces of the gate insulating layer, the one of the source electrode and the drain electrode, the interlayer insulating film, the first electrode layer, the conductive layer, and the second electrode layer are exposed in the opening, and

wherein the first substrate and the side surfaces of the gate insulating layer, the one of the source electrode and the drain electrode, the interlayer insulating film, the first electrode layer, the conductive layer, and the second electrode layer are in contact with the liquid crystal layer.

6. The liquid crystal display device according to claim 5,

wherein the first electrode layer, the second electrode layer, and the third electrode layer each have a comb-like shape.

7. The liquid crystal display device according to claim 5, further comprising a second insulating layer on and in contact with the one of the source electrode and the drain electrode and the conductive layer,

wherein the second insulating layer is interposed between the transistor and the interlayer insulating film.

8. The liquid crystal display device according to claim 5,

wherein the liquid crystal layer includes a photocurable resin and a photopolymerization initiator.

11. The liquid crystal display device according to claim 5,

wherein the semiconductor layer comprises an oxide semiconductor layer, and

wherein the oxide semiconductor layer comprises a crystal region which is c-axis-aligned perpendicularly to a surface of the oxide semiconductor layer.