KR20060101653A - The in-plane switching mode liquid crystal display device and method for fabricating the same - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transverse electric field liquid crystal display device and a method of manufacturing the same in a transverse electric field liquid crystal display device having an ITO-ITO structure, which prevents the occurrence of declining and increases the storage capacitance. A plurality of gate wirings and data wirings defining unit pixels, thin film transistors formed at intersections of the gate wirings and data wirings, common wirings parallel to the gate wirings, and connection portions of pixel electrodes formed in the unit pixels. And a passivation layer formed on the entire surface including the data line, a plurality of common electrodes overlapping one end of the common wiring on the passivation layer, and the other end overlapping the connection portion of the pixel electrode, and parallel to the common electrode. Formed and one end is integrally connected so that the drain of the thin film transistor And a plurality of pixel electrodes which are in contact with the in electrode and whose other end is in contact with the connection portion of the pixel electrode.

IPS, Disclination, Storage Capacitance

Description

Transverse electric field type liquid crystal display device and manufacturing method thereof {THE IN-PLANE SWITCHING MODE LIQUID CRYSTAL DISPLAY DEVICE AND METHOD FOR FABRICATING THE SAME}

1 is a plan view of a unit pixel of a transverse electric field type liquid crystal display device according to the related art.

FIG. 2 is a detailed plan view in I of FIG. 1; FIG.

3A and 3B are diagrams showing rotation directions of liquid crystal molecules.

4 is a plan view of a unit pixel of a transverse electric field type liquid crystal display device according to the present invention;

5A to 5D are cross-sectional views of a transverse electric field liquid crystal display device according to the present invention;

* Explanation of symbols on the main parts of the drawings

112: gate wiring 112a: gate electrode

115: data wiring 115a: source electrode

115b: drain electrode 117: pixel electrode

124: common electrode 125: common wiring

130: pixel electrode connection portion 141, 142, 143: contact hole

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device (LCD), and more particularly, to a transverse electric field type liquid crystal display device having an electrode structure for minimizing a discrepancy generating area and increasing storage capacitance. will be.

Recently, the liquid crystal display device, one of the flat panel display devices that are attracting attention, is an element that changes the optical anisotropy by applying an electric field to a liquid crystal that combines the liquidity and the optical properties of the crystal, which is applied to a conventional cathode ray tube. Compared with its low power consumption, small volume, large size, and high definition, it is widely used.

The liquid crystal display device has a variety of modes depending on the nature of the liquid crystal and the structure of the pattern.

Specifically, the TN mode (Twisted Nematic Mode) for arranging the liquid crystal directors to be twisted by 90 ° and then applying a voltage to the liquid crystal directors, and dividing one pixel into multiple domains to change the viewing angle of each domain to change the wide viewing angle Multi-domain mode to implement, OCB mode (Optically Compensated Birefringence Mode) to compensate the phase change of light according to the direction of light by attaching the compensation film to the outer peripheral surface of the substrate, and two on one substrate In-Plane Switching Mode, which forms an electrode so that the directors of the liquid crystal are twisted in parallel planes of the alignment layer, and VA mode, in which the long axis of the liquid crystal molecules is vertically aligned with the alignment layer plane by using a negative liquid crystal and a vertical alignment layer. (Vertical Alignment), etc.

Among them, the transverse electric field type liquid crystal display device is generally composed of a color filter array substrate and a thin film transistor array substrate disposed opposite to each other and having a liquid crystal layer therebetween.

That is, a black matrix for preventing light leakage and a color filter layer of R, G, and B for implementing color on the black matrix are formed on the color filter array substrate.

The thin film transistor array substrate includes gate wirings and data wirings defining unit pixels, switching elements formed at intersections of the gate wirings and data wirings, and a common electrode and a pixel electrode alternately crossing each other to generate a transverse electric field. Is formed.

Hereinafter, a transverse electric field type liquid crystal display device according to the related art will be described with reference to the accompanying drawings.

1 is a plan view of a unit pixel of a transverse electric field type liquid crystal display device according to the related art, FIG. 2 is a detailed plan view of I of FIG. 1, and FIGS. 3A and 3B are diagrams showing rotation directions of liquid crystal molecules.

Specifically, as illustrated in FIG. 1, a thin film transistor array substrate of a transverse electric field type liquid crystal display device includes a plurality of gate lines 12 arranged in a row and a plurality of gate lines intersecting the gate lines perpendicularly to the gate lines. A unit pixel is defined by the data line 15, and the unit pixel includes a thin film transistor (TFT) that serves as a switching, a plurality of common electrodes 24 parallel to the data line 15, and the common electrode ( The pixel electrode 17 is formed to be alternated between the 24 and parallel to the common electrode 24.

In this case, the common electrode 24 is connected to a common wiring formed on the same layer as the gate wiring to receive a Vcom signal from an external driving circuit. A predetermined region of the common wiring 25 is used as a capacitor lower electrode.

One end of the pixel electrode 17 is integrally connected to the pixel electrode 17 and connected to the drain electrode 15b of the thin film transistor TFT through the first contact hole 18 to receive a pixel signal. A predetermined region of is used as the capacitor upper electrode. Therefore, storage capacitance is generated by the common wiring and the pixel electrode overlapping each other.

In this case, the common electrode may be formed on the same layer as the common wiring or on the same layer as the pixel electrode. First, when the common electrode and the common wiring are formed on the same layer, the two patterns may be integrally formed and common. When the electrode and the pixel electrode are formed on the same layer, the common electrode and the common wiring are connected through the contact hole 19 formed by removing the insulating layer.

On the other hand, when the pixel electrode 17 and the common electrode 24 are formed on the same layer, the pixel electrode 17 and the common electrode 24 are formed of a transparent conductive material such as ITO. In this manner, the pixel electrode and the common electrode are formed of a transparent conductive material such as ITO. It is called ITO-ITO electrode structure.

However, in the case of the transverse electric field type liquid crystal display device having the ITO-ITO structure, as shown in FIG. 2, electric field distortion occurs at the connection portion of the pixel electrode, causing the disclination to occur in this region.

Specifically, as shown in FIG. 2, when a high voltage is applied to the common electrode 24 and a low voltage is applied to the pixel electrode 17, a transverse electric field, which is a horizontal electric field, is generated between the two electrodes. In addition, liquid crystal molecules (not shown), which are initially arranged in the rubbing direction, are rearranged in the direction of the electric field of the transverse electric field to control the transmission of light.

However, since the rotation direction of the liquid crystal molecules 70 in the region A (see FIG. 3A) and the rotation direction of the liquid crystal molecules 70 in the region C (see FIG. 3B) are opposite to each other, the rotation direction of the liquid crystal molecules in the region B is different. Either side can't be defined, and in reality, the rotation of the liquid crystal molecules is distorted. For this reason, a phenomenon in which polarization is hardly transmitted in the B region occurs, which causes a decrease in transmittance of the cell.

In other words, electric field distortion occurs in the region B between the common electrode and the end portion of the pixel electrode, thereby causing disclination. The effective aperture ratio of the pixel is reduced to reduce the luminance of the device.

In the case of the transverse electric field type liquid crystal display device having the ITO-ITO structure, since the pixel electrode and the common electrode are formed on the same layer, the end of the common electrode cannot overlap the pixel electrode connection part, so there is a limit in minimizing the B area and the C area. .

On the other hand, in the case of the transverse electric field type liquid crystal display device, since the electric field direction is horizontal, the storage capacity of the pixel electrode is very small compared to the TN mode liquid crystal display device, whereas the parasitic capacitor (paratic capacity) is the TN mode liquid crystal display. Similar to the device has a disadvantage that the voltage of the pixel electrode is difficult to maintain properly.

However, in the case of a transverse electric field type liquid crystal display device having an ITO-ITO structure, it is also difficult to secure a storage capacity due to overlap of the pixel electrode and the gate wiring layer, and thus it is difficult to secure a sufficient capacity of the pixel electrode. It has a disadvantage in the stability of the liquid crystal cell characteristics.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems. In the transverse electric field type liquid crystal display device having an ITO-ITO structure, the present invention proposes an electrode structure which minimizes the generation area and increases the storage capacity. It is an object of the present invention to provide a transverse electric field type liquid crystal display device and a method of distributing the same, which aim to improve the aperture ratio and improve the stability of liquid crystal cell characteristics.

According to an aspect of the present invention, a transverse electric field type liquid crystal display device includes a plurality of gate lines and data lines vertically intersecting on a substrate to define a unit pixel, and a thin film formed at an intersection point of the gate lines and data lines. One end of the transistor, a common wiring parallel to the gate wiring, a connection portion of the pixel electrode formed in the unit pixel, a passivation film formed on the entire surface including the data wiring, and one end of the common wiring on the passivation film An end is formed to be parallel between the plurality of common electrodes overlapping the connecting portion of the pixel electrode, the common electrode and one end is integrally connected to contact the drain electrode of the thin film transistor, the other end is connected to the connection of the pixel electrode It comprises a plurality of pixel electrodes which are contacted It is done.

In addition, a method of manufacturing a transverse electric field type liquid crystal display device for achieving another object of the present invention includes the steps of forming a gate wiring and a common wiring on a substrate, forming a gate insulating film on the entire surface including the gate wiring; Forming a data line defining a pixel on the gate insulating layer to cross the gate line; forming a connection portion of the pixel electrode in each pixel; and forming a thin film transistor at an intersection point of the gate line and the data line. Forming a protective film on the entire surface including the data line, forming a common electrode on one side of the protective film, the one end of which is in contact with the common wiring and the other end of which overlaps the connection portion of the pixel electrode; The drain electrode and the pixel electrode of the thin film transistor are connected at both ends parallel to the common electrode. And forming a pixel electrode contacted to each of the portions.

In other words, by forming the connection part of the pixel electrode made of a material of another layer and overlapping the end of the common electrode with the connection part of the pixel electrode, it is possible to minimize the declining generation region.

In addition, the connection part of the pixel electrode may be formed at the same time as the data line, and an insulating film (protective film) is further provided between the connection part of the pixel electrode and the common electrode to form a storage capacitor, thereby further securing the storage capacitor. Can be.

Such an electrode structure may be usefully applied to an ITO-ITO structure transflective liquid crystal display device that simultaneously forms a pixel electrode and a common electrode on the same layer.

Hereinafter, the transverse electric field type liquid crystal display device according to the present invention will be described in detail with reference to the accompanying drawings.

4 is a plan view of a unit pixel of a transverse electric field liquid crystal display device according to the present invention, and FIGS. 5A to 5D are cross-sectional views of a process of the transverse electric field liquid crystal display device according to the present invention.

As shown in FIG. 4, a thin film transistor array substrate of a transverse electric field type liquid crystal display device according to the present invention includes a gate having a plurality of gate lines 112 arranged in a line and a gate insulating film (not shown) interposed therebetween. A plurality of data lines 115 defining unit pixels perpendicular to the wirings, thin film transistors (TFTs) serving as switching units, and formed on the same layer as the data lines and separated from the data lines. A connecting portion 130 of the pixel electrode formed in an independent pattern in the unit pixel, a protective film (not shown) formed on the front surface including the data line, and one end are integrally connected to each other to form the first contact hole 141. A plurality of wires contacted to the drain electrode 115b of the thin film transistor and having the other end contacted to the connection part 130 of the pixel electrode through the second contact hole 142. The electrode 117, the common wiring 125 parallel to the gate wiring 112, and one end thereof are in contact with the common wiring through the third contact hole 143 and parallel to the pixel electrode 117. It is formed of a common electrode 124 is formed to generate a transverse electric field.

In this case, the pixel electrode 117 and the common electrode 124 are formed on the same layer on the passivation layer. The common electrode 124 has the other end overlapping the connection part 130 of the pixel electrode. The connection portion and the common electrode of the protective film provided therebetween constitute a storage capacitor.

Since the common wiring 125 is provided on the same layer as the gate wiring 112, the common electrode 124 contacts the common wiring through the third contact hole 143 formed by removing the gate insulating film and the protective film. do.

The pixel electrode 117 contacts the connection portion 130 of the pixel electrode through the second contact hole 142 formed by removing the protective layer.

On the other hand, since the common wiring 125 can extend to the connecting portion 130 of the pixel electrode, it is possible to more secure a region where a transverse electric field is generated between the common electrode and the pixel electrode and to minimize the disclination region. .

The manufacturing method of the transverse electric field liquid crystal display device according to the present invention will be described.

First, as shown in FIG. 5A, to prevent signal delay, a plurality of gate wirings may be formed by depositing and patterning a metal such as aluminum (Al) or aluminum alloy (AlNd: Aluminum Neodymium) having a low resistivity on the substrate. 112, the gate electrode 112a and the common wiring 125 are formed.

In this case, the common wiring 125 is formed to be parallel to the gate wiring 112, and pixel electrodes overlap in a later process to form a storage capacitor.

Next, an inorganic insulating material such as silicon oxide (SiOx) or silicon nitride (SiNx) is generally deposited on the entire surface including the gate wiring 112 by a plasma enhanced chemical vapor deposition (PECVD) method. A gate insulating film (not shown) is formed.

Subsequently, amorphous silicon (a-Si: H) is deposited on the entire surface including the gate insulating film at a high temperature and then patterned to form an independent island-shaped semiconductor layer 114 on the gate insulating film on the gate electrode.

Subsequently, as illustrated in FIG. 5B, metals such as molybdenum (Mo) and molybdenum-tungsten (MoW) are deposited on the entire surface including the semiconductor layer 114 and patterned to form a plurality of data wires 115 and sources. The drain electrodes 115a and 115b and the pixel electrode connecting unit 130 are formed.

The data line 115 is formed to be perpendicular to the gate line 112 in order to define a pixel area, and the source / drain electrodes 115a and 115b are formed at both ends of the semiconductor layer 114, respectively. A thin film transistor for stacking the electrode 112a, the gate insulating film, the semiconductor layer 114, and the source / drain electrodes 115a and 115b to control on / off of the voltage applied to the unit pixel is completed.

The pixel electrode connection unit 130 is formed to be an independent pattern in each pixel, separated from the data line. In particular, it is formed to be parallel to the gate wiring, but formed to be as far as possible from the gate wiring for applying the gate signal to the pixel.

Next, a protective film (not shown) is formed by coating an organic insulating material such as benzocyclobutene (BCB) or an acrylic resin or depositing an inorganic insulating material such as SiNx or SiOx on the entire surface including the data line 115. Form.

Subsequently, as shown in FIG. 5C, a portion of the passivation layer is removed to form a first contact hole 141 through which the drain electrode 115b is exposed, and a second contact through which the pixel electrode connection unit 130 is exposed. The hole 142 is formed. A portion of the passivation layer and the gate insulation layer are removed to form a third contact hole 143 through which the common wiring 125 is exposed.

Subsequently, as illustrated in FIG. 5D, a pixel electrode for generating a transverse electric field in parallel with each other by depositing and patterning a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO) on the entire surface including the passivation layer ( 117 and a plurality of common electrodes 124 are formed.

The common electrode 124 and the pixel electrode 117 may be formed in a straight line shape or may be formed in a zigzag shape.

One end of the pixel electrode 117 is integrally connected to the drain electrode 115b through the first contact hole 141, and the other end of the pixel electrode 117 is connected to the pixel electrode 117 through the second contact hole 142. It contacts each of the connection part 130.

In addition, one end of the common electrode 124 is electrically connected to the common wiring 125 through the third contact hole 143, and the other end thereof overlaps the connection part 130 of the pixel electrode.

Such a transverse electric field type liquid crystal display device can extend the common electrode up to the pixel electrode connection part in the type in which the pixel electrode and the common electrode are formed on the same layer, thereby minimizing the disclination area, and the pixel electrode connection part. By overlapping the common electrodes, it is possible to further secure storage capacitance.

On the other hand, the present invention described above is not limited to the above-described embodiment and the accompanying drawings, it is possible that various substitutions, modifications and changes within the scope without departing from the technical spirit of the present invention. It will be apparent to those of ordinary skill in Esau.

That is, in the above description, the connection portion of the pixel electrode is limited to the contents formed at the same time as the data line.

As described above, the transverse electric field type liquid crystal display device and the method of manufacturing the same according to the present invention have the following effects.

First, the effective aperture ratio of the ITO-ITO structure IPS is improved by removing the disclination region by forming the connection portion between the pixel electrode and the pixel electrode in another layer and overlapping the common electrode formed on the same layer with the pixel electrode. Let's do it.

Second, by increasing the storage capacity by overlapping the connection portion of the pixel electrode and the common electrode, it is possible to secure a sufficient capacity of the pixel electrode to stabilize the liquid crystal cell characteristics.

Claims (13)

A plurality of gate wirings and data wirings vertically crossing the substrate to define the unit pixels; A thin film transistor formed at an intersection point of the gate line and the data line; A common wiring parallel to the gate wiring; A connection part of the pixel electrode formed in the unit pixel; A protective film formed on the entire surface including the data line; A plurality of common electrodes having one end contacting the common wiring on the passivation layer and the other end overlapping a connection portion of the pixel electrode; And a plurality of pixel electrodes which are formed to be parallel between the common electrodes, one end of which is integrally connected to contact the drain electrode of the thin film transistor, and the other end of which contacts the connecting portion of the pixel electrode. Electric field type liquid crystal display device. The method of claim 1, And a connection portion of the pixel electrode is formed on the same layer as the data line. The transverse electric field liquid crystal display device of claim 2, wherein the connection portion of the pixel electrode is formed in a separate pattern from the data line. The method of claim 1, And a protective layer provided between the connecting portion of the pixel electrode, the common electrode, and a protective film disposed therebetween to form a storage capacitor. The method of claim 1, And the common electrode and the pixel electrode are provided on the same layer. The method of claim 1, The common wiring is a horizontal field type liquid crystal display device, characterized in that provided on the same layer as the gate wiring. Forming a gate wiring and a common wiring on the substrate; Forming a gate insulating film on the entire surface including the gate wiring; Forming a data line on the gate insulating film to define a pixel crossing the gate line; Forming a connection portion of a pixel electrode in each pixel; Forming a thin film transistor at an intersection point of the gate line and the data line; Forming a protective film on the entire surface including the data line; Forming a common electrode on the passivation layer, one end of which is in contact with the common wiring and the other end of which overlaps the connection of the pixel electrode; And forming a pixel electrode which is parallel to the common electrode and whose both ends are in contact with a drain electrode of the thin film transistor and a connection portion of the pixel electrode, respectively. The method of claim 7, wherein And a connecting portion of the pixel electrode to form an independent pattern in each pixel. The method of claim 7, wherein And a connecting portion of the data line and the pixel electrode is formed at the same time. The method of claim 7, wherein And the common electrode and the pixel electrode are formed on the same layer at the same time. The method of claim 7, wherein And the common electrode and the pixel electrode are made of ITO. The method of claim 7, wherein And the common electrode contacts the common wiring through a contact hole formed by removing the gate insulating film and the protective film. The method of claim 7, wherein And the pixel electrode contacts the connection portion of the pixel electrode through a contact hole formed by removing the protective layer.

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