Liquid crystal display device and method for manufacturing the same

Abstract

The present invention provides a liquid crystal display device to be operated at high speed and with high precision by improving performance of a thin-film transistor without increasing cross capacity of gate lines and data lines. On an upper layer of a gate insulator GI at an intersection of gate lines GL and data lines DL to be prepared on an active matrix substrate SUB1, which makes up a liquid crystal display panel of a liquid crystal display device, an insulating material with low dielectric constant is dropped by ink jet coating method to prepare another insulator LDP in order to improve performance characteristics of the thin-film transistor to be prepared on a silicon semiconductor layer SI without increasing cross capacity on said intersection.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 represents plan views to explain essential processes of a method for manufacturing an active matrix substrate of a liquid crystal display panel, which constitutes Embodiment 1 of a liquid crystal display device according to the present invention;

FIG. 2 is a cross-sectional view along the line A-A of the active matrix substrate when data lines are prepared in a process (4) as shown in FIG. 1;

FIG. 3 represents plan views to explain essential processes of a method for manufacturing the active matrix substrate of the liquid crystal display panel, which constitutes Embodiment 2 of the liquid crystal display device of the present invention;

FIG. 4 is a cross-sectional view along the line A-A of the active matrix substrate when data lines are prepared in a process (4) as shown in FIG. 3;

FIG. 5 represents plan views to explain essential processes of a method for manufacturing the active matrix substrate of the liquid crystal display panel, which constitutes Embodiment 3 of the liquid crystal display device of the present invention;

FIG. 6 is a cross-sectional view along the line A-A of the active matrix substrate when data lines are prepared in a process (4) as shown in FIG. 5;

FIG. 7 represents plan views to explain essential processes of a method for manufacturing the active matrix substrate of the liquid crystal display panel, which constitutes Embodiment 4 of the liquid crystal display device of the present invention;

FIG. 8 is a cross-sectional view along the line A-A of the active matrix substrate when data lines are prepared in a process (4) as shown in FIG. 7;

FIG. 9 represents plan views to explain essential processes of a method for manufacturing the active matrix substrate of the liquid crystal display panel, which constitutes Embodiment 5 of the liquid crystal display device of the present invention;

FIG. 10 is a cross-sectional view of the active matrix substrate along the line B-B when data lines are prepared in the process (4) of FIG. 9 and another substrate is attached to seal the liquid crystal;

FIG. 11 represents plan views to explain essential processes of a method for manufacturing the active matrix substrate of the liquid crystal display panel, which constitutes Embodiment 6 of the liquid crystal display device of the present invention;

FIG. 12 is a cross-sectional view of the active matrix substrate along the line B-B when data lines are prepared in the process (4) of FIG. 11 and another substrate is attached to seal the liquid crystal;

FIG. 13 represents plan views to explain essential processes of a method for manufacturing the active matrix substrate of the liquid crystal display panel, which constitutes Embodiment 7 of the liquid crystal display device of the present invention;

FIG. 14 is a cross-sectional view of the active matrix substrate along the line B-B when data lines are prepared in the process (4) of FIG. 13 and another substrate is attached to seal the liquid crystal;

FIG. 15 represents plan views to explain essential processes of a method for manufacturing the active matrix substrate of the liquid crystal display panel, which constitutes Embodiment 8 of the liquid crystal display device of the present invention;

FIG. 16 is a cross-sectional view of the active matrix substrate along the line B-B when data lines are prepared in the process (4) of FIG. 15 and another substrate is attached to seal the liquid crystal;

FIG. 17 represents an equivalent circuit of a display panel unit of a liquid crystal display device of active matrix type; and

FIG. 18 represents drawings to explain an arrangement of a pixel unit PXL of a display panel PNL shown in FIG. 17 and an arrangement of a thin-film transistor TFT to constitute a pixel unit PXL.

Claims

1. A liquid crystal display device with a liquid crystal interposed between a first insulating substrate and a second insulating substrate, wherein said liquid crystal display device comprises: a plurality of gate lines prepared in parallel to each other and disposed on said first insulating substrate;a plurality of data lines prepared in parallel to each other and being disposed to intersect via said gate line insulating layer;each of regions enclosed by said gate lines and said data lines is regarded as a unit pixel region, and a region where said plurality of gate lines and said plurality of data lines cross each other makes up a display region;said liquid crystal display device further comprising a thin-film transistor, consisting of a gate electrode extending from said gate line to said unit pixel region, a gate insulator to cover said gate line and said gate electrode, a semiconductor layer sequentially prepared on said gate insulator, an ohmic contact layer separately prepared on surface of said semiconductor layer, and a source electrode and a drain electrode formed on said separated ohmic contact layer; andsaid insulating layer at the intersection of said gate line and said data line has a 2-layer structure, comprising said gate insulator and an insulator with low dielectric constant prepared by ink jet coating on an upper layer or on a lower layer of said gate insulator.

2. A liquid crystal display device with a liquid crystal interposed between a first insulating substrate and a second insulating substrate, wherein said liquid crystal display device comprises: a plurality of gate lines prepared in parallel to each other and disposed on said first insulating substrate;a plurality of data lines prepared in parallel to each other and being disposed to intersect via said gate line insulating layer;each of regions enclosed by said gate lines and said data lines is regarded as a unit pixel region, and a region where said plurality of gate lines and said plurality of data lines cross each other makes up a display region;said liquid crystal display device further comprising a thin-film transistor, consisting of a gate electrode extending from said gate line to said unit pixel region, a gate insulator to cover said gate line and said gate electrode, a semiconductor layer sequentially prepared on said gate insulator, an ohmic contact layer separately prepared on surface of said semiconductor layer, and a source electrode and a drain electrode formed on said separated ohmic contact layer; andover the entire area of said display region, said gate insulating layer on said gate line has a 2-layer structure, comprising said gate insulator and an insulator with low dielectric constant prepared by ink jet coating along said gate line on an upper layer or on a lower layer of said gate insulator.

3. A liquid crystal display device according to claim 1 or 2, wherein said insulator with low dielectric constant is a heat-resistant resin.

4. A liquid crystal display device according to claim 1 or 2, wherein said insulator with low dielectric constant is an aromatic hydrocarbon type organic polymer or a polyallyl ether type organic polymer.

5. A method for manufacturing a liquid crystal display device with a liquid crystal interposed between a first insulating substrate and a second insulating substrate, said method comprising the steps of: preparing a plurality of gate lines running in parallel to each other on said first insulating substrate;depositing a gate insulator to cover said first insulating substrate including said gate lines;preparing an insulator with low dielectric constant by ink jet coating method on said gate insulator of a portion where said gate line and said data line cross each other; andpreparing a plurality of data lines running in parallel to each other by making said gate lines cross on said gate line insulating layer and said insulator with low dielectric constant.

6. A method for manufacturing a liquid crystal display device with a liquid crystal interposed between a first insulating substrate and a second insulating substrate, said method comprising the steps of: preparing a plurality of gate lines running in parallel to each other on said first insulating substrate;preparing an insulator with low dielectric constant by ink jet coating method on said gate lines of a portion where said gate line and said data line cross each other;depositing a gate insulator to cover said first insulating substrate including said gate lines and said insulator with low dielectric constant; andpreparing a plurality of data lines running in parallel to each other by making said gate lines cross on said insulator with low dielectric constant and said gate line insulating layer.

7. A method for manufacturing a liquid crystal display device with a liquid crystal interposed between a first insulating substrate and a second insulating substrate, said method comprising the steps of: preparing a plurality of gate lines running in parallel to each other on said first insulating substrate;depositing a gate insulator to cover said first insulating substrate including said gate lines;preparing an insulator with low dielectric constant by ink jet coating method on said gate insulator along said gate line; andpreparing a plurality of data lines by making said gate lines cross on said gate line insulating layer and said insulator with low dielectric constant.

8. A method for manufacturing a liquid crystal display device with a liquid crystal interposed between a first insulating substrate and a second insulating substrate, said method comprising the steps of: preparing a plurality of gate lines running in parallel to each other on said first insulating substrate;preparing an insulator with low dielectric constant by dropping ink according to ink jet coating method on said gate insulator along said gate lines;depositing a gate insulator to cover said first insulating substrate including said gate lines; andpreparing a plurality of data lines running in parallel to each other by making said gate lines cross on said insulator with low dielectric constant and said gate line insulating layer.

9. A method for manufacturing a liquid crystal display device according to one of claims 5 to 8, said method further comprising a step of: preparing a thin-film transistor, said thin-film transistor has a semiconductor layer on said gate insulating layer and an ohmic contact layer separately provided on surface of said semiconductor layer, a source electrode and a drain electrode being prepared on said separate ohmic contact layer, and a display region is made up with unit pixels to be formed on each portion enclosed by said plurality of gate lines and said plurality of data lines.

10. A method for manufacturing a liquid crystal display device according to one of claims 5 to 8, wherein said insulator with low dielectric constant is a heat-resistant resin.

11. A method for manufacturing a liquid crystal display device according to one of claims 5 to 8, wherein said insulator with low dielectric constant is an aromatic hydrocarbon type organic polymer or a polyallyl ether type organic polymer.