KR0156206B1 - Storage capacitor forming method and structure of liquid crystal display element - Google Patents

Abstract

The present invention relates to a method and a structure for forming a storage capacitor of a liquid crystal display device, and more particularly, to a method and a structure for forming a storage capacitor of a liquid crystal display device suitable for increasing the capacity of a storage capacitor formed by a pixel electrode and a gate line per unit cell. It is about.

The storage capacitor forming method of the liquid crystal display device of the present invention for this purpose in the manufacturing process of the liquid crystal display device having a plurality of gate wirings on the insulating substrate, a plurality of data wirings orthogonal thereto and pixel electrodes in each pixel region, the gate on the substrate Forming a plurality of gate lines with electrodes and forming a gate insulating film on the entire surface; forming an active layer and an ohmic contact layer on the gate electrode to form a thin film transistor; forming a source / drain electrode in the thin film transistor formation region. Simultaneously forming a first metal layer on a neighboring gate insulating film, forming a protective film having contact holes on the drain electrode and the first metal layer, and connecting the drain electrode and the first metal layer through contact holes. And forming a pixel electrode in the pixel region if possible. The storage capacitor structure of the liquid crystal display device of the present invention is a liquid crystal display device having a plurality of gate lines, a gate insulating film and a pixel electrode on a protective film on a substrate, wherein a first metal layer is selectively formed on the gate insulating film. The passivation layer having contact holes is formed on the first metal layer, and a pixel electrode is formed on the first metal layer and the pixel region.

Description

Method and Structure of Storage Capacitor in Liquid Crystal Display Devices

1 is a layout diagram of a storage capacitor of a conventional liquid crystal display device.

FIG. 2 is a cross sectional view of the process taken along line AA ′ of FIG. 1.

3 is a layout diagram of a storage capacitor of a liquid crystal display device according to a first embodiment of the present invention.

4 is a cross-sectional view of the process taken along line AA ′ of FIG. 3.

5 is a layout diagram of a storage capacitor of a liquid crystal display device according to a second embodiment of the Bonner invention.

6 is a cross-sectional view taken along line A-A 'of FIG.

* Explanation of symbols for main parts of the drawings

41 substrate 42 gate electrode

42a: gate line 42a ': storage line

43: gate insulating film 44: active charge

45 doped layer 46a, 46b source / drain electrode

46c: first metal layer 47: protective film

47a: contact hole 47b: through hole

48: pixel electrode

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a structure for forming a storage capacitor of a liquid crystal display device. In particular, the storage capacitor of the liquid crystal display device is adapted to increase the capacity of a storage capacitor selectively formed in the pixel electrode region for each unit cell. It relates to a formation method and a structure.

Hereinafter, a storage capacitor forming method and a structure of a conventional liquid crystal display device will be described with reference to the accompanying drawings.

FIG. 1 is a layout diagram of a storage capacitor of a conventional liquid crystal display device, and FIG. 2 is a process cross-sectional view taken along line AA ′ of FIG. 1, and the gate is disposed on the transparent insulating substrate 21 as shown in FIG. A plurality of gate lines 22a having protrusions are formed on the electrode 22, a gate insulating film 23, an amorphous silicon layer as an active layer, and a doping layer for ohmic contact are deposited on the entire surface, and then the gate electrode 22. The active layer 24 and the doped layer 25 are patterned so as to remain only in the upper transistor formation region.

Subsequently, as shown in FIG. 2B, a metal layer is deposited on the entire surface and patterned to form a plurality of data lines having protrusions with the source electrode 26a in a direction perpendicular to the gate line 22a.

In this case, the drain electrode 26b is formed in the pixel region opposite to the source electrode.

Subsequently, the doping layer of the channel portion is patterned using source / drain electrodes 26a and 26b to form a channel of the transistor, and then forms a protective film 27 to protect the transistor as shown in FIG. .

Next, before forming the pixel electrode on the passivation layer 27, a contact hole 27a is formed in the passivation layer surrounding the drain to electrically contact the drain electrode 26b and the pixel electrode.

Subsequently, as illustrated in FIG. 2D, the transparent metal for forming the pixel is deposited and patterned to form the pixel electrode 28 in the pixel region.

In this case, the drain electrode 26b and the pixel electrode 28 contact with each other through the contact hole 27a, and the storage capacitor is patterned so that the neighboring gate line 22a and the pixel electrode 28 overlap with each other. Form.

That is, a capacitor having a dielectric formed between the pixel electrode 28 and the adjacent gate line 22a is formed.

The storage capacitor operation of the conventional liquid crystal display device formed as described above is as follows.

When the gate driving signal is applied to the gate line, the thin film transistor is turned on so that the data signal applied to the data line is applied to the pixel electrode to drive the liquid crystal.

In this case, the data signal applied to the pixel electrode is induced in the storage capacitor to drive the liquid crystal for a predetermined time even when the thin film transistor is turned off.

However, the storage capacitor of the conventional liquid crystal display device as described above has the following problems.

A storage capacitor formed by overlapping pixel electrodes on a neighboring gate line has a double structure insulating film consisting of a gate insulating film and a protective film formed between two adjacent gate lines and a pixel electrode, thereby forming an insulating film having a double structure insulating film. Due to the thickness, the capacity of the storage capacitor is reduced, and when the signal is applied to the gate electrode, the signal applied to the pixel electrode through the drain electrode does not induce sufficient charge to drive the liquid crystal. Therefore, the flicker of the liquid crystal display increases, resulting in deterioration in image quality. do.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and in the case of the source / drain process, by selectively forming the same electrode as the source / drain in the pixel portion, the storage of the liquid crystal display device suitable for increasing the capacity of the storage capacitor is provided. It is an object of the present invention to provide a method and a structure for forming a capacitor.

The storage capacitor forming method of the liquid crystal display device of the present invention for achieving the above object in the manufacturing process of the liquid crystal display device having a plurality of gate wirings on the insulating substrate, a plurality of data wirings orthogonal thereto and pixel electrodes in each pixel region, Forming a plurality of gate lines having a gate electrode on the substrate and forming a gate insulating film on the front surface; forming an active layer and an ohmic contact layer on the gate electrode to form a thin film transistor; and source in the thin film transistor formation region. / Forming a drain electrode and selectively forming a first metal layer on a neighboring gate insulating film, forming a protective film having contact holes on the drain electrode and the first metal filling, drain electrode and the first through the contact hole 1 includes forming a pixel electrode in the pixel region so as to be connected to the metal layer In the liquid crystal display device having a plurality of gate lines, a gate insulating film, and a pixel electrode on the passivation layer, the storage capacitor structure of the liquid crystal display device of the present invention is characterized in that the first metal layer is selectively formed on the gate insulating film. And a protective film having contact holes on the first metal layer, and a pixel electrode formed on the first metal layer and the pixel region.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

3 and 5 are layout diagrams of storage capacitors of the first and second exemplary embodiments of the present invention, and FIG. 4 is a cross-sectional view taken along line AA ′ of FIG. 3, and FIG. 6 is AA ′ of FIG. 5. The process cross-sectional view along the line shows a gate line 42a and a storage line having a gate electrode 42 protruding on the transparent insulating substrate 41 as shown in FIGS. 4A and 6A. 42a '), a plurality of gate insulating layers 43 and an active layer of amorphous silicon and a doping layer for ohmic contacts are deposited on the entire surface, and the active layer is patterned by patterning an amorphous silicon layer and an ohmic contact layer so that only the transistors of each pixel remain. 44 and the doped layer 45 are formed.

Subsequently, as in FIG. 4 (b), metal is deposited and patterned to form source / drain electrodes to form source / drain electrodes 46a and 46b.

At this time, when the source / drain electrodes 46a and 46b are simultaneously formed, the first metal layer 46c is formed to remain in the region where the storage capacitor is to be formed on the gate insulating layer 43 above the neighboring gate line 42a.

In addition, when forming the source / drain electrodes 46a and 46b as shown in FIG. 6 (b), the first metal layer is formed in the region where the storage capacitor is formed on the gate insulating film on the storage line 42a 'side. It forms 46c.

The doped layer 45 of the channel portion is then patterned using source / drain electrodes 46a and 46b as a mask to make the channel of the transistor.

Next, as shown in FIGS. 4C and 6C, a protective film 47 is formed on the entire surface of the transistor to protect the transistor.

Subsequently, before forming the pixel electrode on the passivation layer 47, the passivation layer on the drain electrode 46b and the first metal layer 46c such that the drain electrode 46b and the first metal layer 46c are in electrical contact with the pixel electrode. 47) is selectively removed to form contact holes 47a and 47b.

Subsequently, as illustrated in FIGS. 4D and 6D, a transparent metal is deposited and patterned to form a pixel to form the pixel electrode 48.

Here, the drain electrode 46b formed of chromium (Cr), chromium / aluminum (Cr / Al), or an alloy of chromium (Cr) and aluminum (Al), or the like, has a pixel electrode 48 through the contact hole 47a of the protective film. The first metal layer 46c contacts the pixel electrode 48 through the through hole 47b of the passivation layer to form a storage capacitor in contact with the upper redundancy.

The operation of the liquid crystal display device storage capacitor of the present invention described as described above is the same as before.

As described above, the effect of the storage capacitor of the liquid crystal display device of the present invention is as follows.

By forming a metal in the region where the storage capacitor is to be formed in the vertical direction above the gate line, the gate insulating film and the protective film are formed to compensate for the capacity decrease of the conventional storage capacitor due to the increase in thickness, thereby increasing the capacity of the storage capacitor connected to the pixel. You can.

Therefore, it is possible to improve the image quality of the liquid crystal display by reducing the occurrence of flicker.

Claims (11)

In the manufacturing process of a liquid crystal display device having a plurality of gate wirings on the insulating substrate, a plurality of data wirings orthogonal thereto, and a pixel electrode in each pixel region, a plurality of gate lines having gate electrodes are formed on the substrate and the gate insulating film is formed on the entire surface of the insulating substrate. Forming a; Forming an active layer and an ohmic contact layer on the gate electrode to form a thin film transistor; Forming a source / drain electrode in the thin film transistor forming region and selectively forming a first metal layer on a neighboring gate insulating film; Forming a protective film having contact holes on the drain electrode and the first metal layer; And forming a pixel electrode in the pixel region to be connected to the drain electrode and the first metal layer through the contact hole. The method of claim 1, wherein the first metal layer is formed of the same metal as the source / drain electrodes. The method of claim 1, wherein the first metal layer is formed of one of chromium (Cr), chromium / aluminum (Cr / Al), and an alloy of chromium and aluminum. The method of claim 1, wherein the first metal layer is formed for a storage capacitor. The method of claim 1, wherein the first metal layer has at least one surface larger or smaller than a pixel electrode. A liquid crystal display device having a plurality of gate lines, a gate insulating film, and a pixel electrode on a protective film on a substrate, wherein a first metal layer is selectively formed on the gate insulating film, and a protective film having a contact hole is formed on the first metal layer. The storage capacitor structure of the liquid crystal display device, characterized in that the pixel electrode is formed in the first metal layer and the pixel region. 7. The story capacitor structure of claim 6, wherein the first metal layer is formed of the same metal as the source / drain electrodes. 7. The storage capacitor structure of claim 6, wherein the first metal layer is formed of one of chromium (Cr), chromium / aluminum (Cr / Al), and an alloy of chromium and aluminum. The storage capacitor structure of claim 6, wherein the first metal layer is formed for a storage capacitor. 7. The storage capacitor structure of claim 6, wherein the first metal layer is formed on a gate insulating layer above a neighboring gate line when forming a source / drain. 7. The storage capacitor structure of claim 6, wherein the first metal layer has at least one surface formed larger or smaller than the pixel electrode.