KR100885844B1 - Liquid crystal display device and method of fabricating thereof - Google Patents

Abstract

In the present invention, the metal layer formed on the pad of the liquid crystal display device is formed of an anisotropic conductive film. The protective layer laminated on the pad is an organic protective layer, and is melted by applying a high temperature in contact with the anisotropic conductive film, and at the same time, the anisotropic conductive film is attached to the pad to form a metal layer to prevent oxidation of the pad. do. As such, by using the organic protective layer and the anisotropic conductive film, the number of masks used can be reduced, and as a result, a simplified manufacturing process is possible.

LCD, transverse electric field mode, pad, anisotropic conductive film, organic protective layer, mask

Description

Liquid crystal display device and manufacturing method therefor {LIQUID CRYSTAL DISPLAY DEVICE AND METHOD OF FABRICATING THEREOF}

1 is a plan view showing the structure of a transverse electric field mode liquid crystal display device.

2A is a cross-sectional view taken along the line II ′ of FIG. 1.

Fig. 2B is a sectional view showing the structure of a pad region of the transverse electric field mode liquid crystal display device.

3A to 3D are diagrams illustrating a manufacturing method of a conventional transverse electric field mode liquid crystal display device.

4A to 4D are views showing a method of manufacturing a transverse electric field mode liquid crystal display device according to the present invention.

5A and 5B illustrate a method of forming an anti-oxidation metal layer of a pad region.

Explanation of symbols on the main parts of the drawings

105: common electrode 107: pixel electrode

108: pad 111: gate electrode

112: semiconductor layer 113: source electrode

114: drain electrode 120,130: substrate

122: gate insulating layer 124: protective layer

129: anti-oxidation metal layer 132: black matrix                 

134: color filter layer 140: liquid crystal layer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device. In particular, the protective film is formed of an organic material, and the anisotropic conductive film is contacted with the organic protective film on the pad, and then pressurized at a high temperature to form a metal layer on the pad, thereby simplifying the manufacturing process. A liquid crystal display device and a method for manufacturing the same.

Recently, with the development of various portable electronic devices such as mobile phones, PDAs, and notebook computers, there is a growing demand for flat panel display devices for light and thin applications. Such flat panel displays are being actively researched, such as LCD (Liquid Crystal Display), PDP (Plasma Display Panel), FED (Field Emission Display), and VFD (Vacuum Fluorescent Display). Liquid crystal display devices (LCDs) are in the spotlight for reasons of implementation.

Such liquid crystal display devices have various display modes according to the arrangement of liquid crystal molecules. However, TN mode liquid crystal display devices are mainly used because of the advantages of easy monochrome display, fast response speed, and low driving voltage. In such a TN mode liquid crystal display device, liquid crystal molecules aligned horizontally with the substrate are almost perpendicular to the substrate when a voltage is applied. Therefore, there is a problem that the viewing angle is narrowed upon application of voltage due to the refractive anisotropy of the liquid crystal molecules.

In order to solve this viewing angle problem, liquid crystal display devices of various modes having wide viewing angle characteristics have recently been proposed, but among them, the liquid crystal display device of the lateral field mode (In Plane Switching Mode) is applied to actual production. It is produced. The IPS mode liquid crystal display device aligns liquid crystal molecules in a plane by forming at least one pair of electrodes arranged in parallel in a pixel to form a transverse electric field substantially parallel to the substrate.

1 illustrates a structure of a conventional IPS mode liquid crystal display device. As shown in the figure, the pixels of the liquid crystal panel 1 are defined by gate lines 3 and data lines 4 arranged vertically and horizontally. Although only the (n, m) th pixels are shown in the drawing, in the liquid crystal panel 1, n and m gate lines 3 and data lines 4 are disposed, respectively, and thus the liquid crystal panel 1 is disposed. N x m pixels are formed throughout. The thin film transistor 10 is formed at the intersection of the gate line 3 and the data line 4 in the pixel. The thin film transistor 10 includes a gate electrode 11 to which a scan signal is applied from the gate line 3, and a semiconductor layer formed on the gate electrode 11 and activated as a scan signal is applied to form a channel layer. 12 and a source electrode 13 and a drain electrode 14 formed on the semiconductor layer 12 and to which an image signal is applied through the data line 4. The image signal input from the outside is applied to the liquid crystal layer. do.

In the pixel, a plurality of common electrodes 5 and a pixel electrode 7 are arranged substantially parallel to the data line 4. In addition, a common line 16 connected to the common electrode 5 is disposed in the middle of the pixel, and a pixel electrode line 18 connected to the pixel electrode 7 is disposed on the common line 16. It overlaps with the common line 16. Storage capacitance is formed in the transverse electric field mode liquid crystal display by overlapping the common line 16 and the pixel electrode line 18.

As described above, in the configured IPS mode liquid crystal display device, the liquid crystal molecules are oriented substantially in parallel with the common electrode 5 and the pixel electrode 7. When the thin film transistor 10 is operated to apply a signal to the pixel electrode 7, a transverse electric field substantially parallel to the liquid crystal panel 1 is generated between the common electrode 5 and the pixel electrode 7. Since the liquid crystal molecules rotate on the same plane along the transverse electric field, gray level inversion due to the refractive anisotropy of the liquid crystal molecules can be prevented.

FIG. 2A is a cross-sectional view taken along the line II ′ of FIG. 1. As shown in FIG. 2A, a gate electrode 11 is formed on the first substrate 20, and a gate insulating layer 22 is stacked over the entire first substrate 20. The semiconductor layer 12 is formed on the gate insulating layer 22, and the source electrode 13 and the drain electrode 14 are formed thereon. In addition, a passivation layer 24 is formed on the entire first substrate 20.

In addition, a plurality of common electrodes 5 are formed on the first substrate 20, and a pixel electrode 7 is formed on the gate insulating layer 22, so that the common electrode 5 and the pixel electrode 7 are interposed therebetween. A lateral electric field occurs in the

The black matrix 32 and the color filter layer 34 are formed on the second substrate 30. The black matrix 32 is to prevent light leakage into an area where the liquid crystal molecules do not operate. As shown in the drawing, the black matrix 32 is between the region of the thin film transistor 10 and the pixel and the pixel (ie, the gate line and the data line). Area). The color filter layer 34 is composed of R (Red), B (Blue), and G (Green) to realize actual colors.

The liquid crystal layer 40 is formed between the first substrate 20 and the second substrate 30 to complete the liquid crystal panel 1.

2B is a diagram showing a pad region of the transverse electric field mode liquid crystal display device. As shown in the figure, a pad 8 is formed on the gate insulating layer 22, and a protective layer 24 is formed on the pad 8. The protective layer 24 is made of an inorganic material such as SiO ₂ or SiNx. A contact hole 27 is formed in the protective layer 24 on the pad 8 so that the pad 8 is opened to the outside. . The open pad 8 is connected to an external driving element so that a signal is applied to the pixel. The metal layer 29 is formed in the contact hole 27 of the protective layer 24. The pad 8 is exposed to the outside during the manufacturing process of the IPS mode liquid crystal display device and is prevented from being oxidized by contact with air. The pad 8 is made of a transparent material such as indium tin oxide (ITO).

3A to 3D show a method of manufacturing the IPS mode liquid crystal display device having the above structure. In this case, the IPS mode liquid crystal display device is divided into a pixel area and a pad area for convenience of description.

First, as shown in FIG. 3A, the gate electrode 11 and the common electrode 5 are formed in the pixel region by laminating and etching metal on the first substrate 20 made of a transparent material such as glass. The gate insulating layer 22 is laminated over the entire substrate 20. Subsequently, as illustrated in FIG. 3B, a semiconductor material is stacked and etched in the pixel region of the gate insulating layer 22 to form the semiconductor layer 12, and then the source electrode 13 and the semiconductor layer 12 are disposed on the semiconductor layer 12. The drain electrode 14 is formed. In addition, at the same time as the source electrode 13 and the drain electrode 14, the pixel electrode 7 is formed in the pixel region and the pad 8 is formed in the pad region.

Thereafter, as shown in FIG. 3C, the protective film 24 made of the inorganic material is formed over the entire first substrate 20, and then the protective layer 24 on the pad 8 formed in the pad region is formed. The pad 8 is opened by forming a contact hole 27. Subsequently, a transparent material such as ITO is deposited on the protective layer 24 and then etched to form a metal layer 29 in the contact hole 27 on the pad 8.

Meanwhile, a black matrix 32 and a color filter layer 34 are formed on the second substrate 30, and as shown in FIG. 3 (d), the first substrate 20 and the second substrate 30 are formed. The liquid crystal layer 40 is formed by bonding and injecting the liquid crystal therebetween to complete the IPS mode liquid crystal display device.

In the IPS mode liquid crystal display device manufacturing method, a mask for forming a gate electrode and a common electrode, a mask for forming a semiconductor layer, a mask for forming a source / drain electrode and a pixel electrode, and a mask for forming a protective layer are used. There is a need for a mask for forming an ITO metal layer. As described above, since a total of five masks are required in the conventional IPS mode liquid crystal display device, the manufacturing process is complicated. In order to simplify the manufacturing process of the IPS mode liquid crystal display device, research has been conducted to reduce the number of masks, but there is no effective method for reducing the number of masks.

The present invention has been made in view of the above, and the liquid crystal which can simplify the manufacturing process by forming a protective layer as an organic protective layer, melting the organic protective layer and attaching a conductive film to the pad to form an anti-oxidation metal layer of the pad. An object of the present invention is to provide a display element and a method of manufacturing the same.

In order to achieve the above object, the liquid crystal display device according to the present invention is defined by a gate line and a data line, the pixel region is formed of a plurality of pixels in which a thin film transistor is formed to form an electric field between the pixel electrode and the common electrode; The pad region includes a pad area formed at an outer portion of the pixel area, the pad area including a pad for applying an external signal to the pixel area, and a conductive film, and a metal layer formed on the pad to prevent oxidation of the pad.

An organic protective layer made of an organic material is formed on the pad of the pad region, and the conductive film is an anisotropic conductive film having conductive balls dispersed therein. When the conductive film is pressed while applying high temperature heat while the conductive film is in contact with the organic protective layer on the pad, the organic protective layer on the pad is melted and the anisotropic conductive film adheres to the pad to prevent oxidation of the metal layer. This is to be formed.

The liquid crystal display element of this invention is not limited to the liquid crystal display element of a specific mode or structure. For example, the present invention may also be applied to liquid crystal display devices having various modes, such as IPS mode liquid crystal display devices, TN mode liquid crystal display devices, VA mode liquid crystal display devices, or liquid crystal display devices having various structures.

In addition, the manufacturing method of the liquid crystal display device of the present invention comprises the steps of preparing a substrate consisting of a pixel region and a pad region, forming a plurality of gate lines and data lines in the pixel region of the substrate, and a plurality of in the pixel region Forming a thin film transistor, forming a pad in the pad region, forming a protective layer over the entire substrate, and forming a metal layer of a conductive film on the pad.

The present invention provides a method of a simplified liquid crystal display device. In addition, the present invention provides a structure of a liquid crystal display device manufactured by a simplified method. In particular, the present invention reduces the number of masks by removing the ITO layer formed to prevent oxidation of the pads.

The pad connects the electrode of the liquid crystal panel with an external driving device. In addition, the pad is formed on the lower substrate of the liquid crystal panel so as to be located outside the liquid crystal panel. Thus, unlike the pixels inside the panel, since the pad is exposed to the outside, it is oxidized in contact with the outside air. When the pad is oxidized, the contact with the external driving device becomes worse, and as a result, the signal of the driving device is not applied to the electrode inside the panel. Accordingly, a metal layer is formed on the pad to prevent oxidation of the pad. In the present invention, the metal layer is formed of an anisotropic conductive film so that the mask for forming a metal layer is not used. To this end, in the present invention, the protective layer is formed of an organic material, and the metal layer is formed by attaching the anisotropic conductive film to the pad by removing the protective layer on the pad by applying pressure at a high temperature after contacting the anisotropic conductive film to the protective layer. To form.

As described above, in the liquid crystal display device of the present invention, the number of masks used is reduced by not using the mask for forming the metal layer, and as a result, the manufacturing process of the liquid crystal display device can be simplified.

The structure or manufacturing method of the liquid crystal display device according to the present invention is not limited to the liquid crystal display device having a specific structure. For example, the present invention may be applied to liquid crystal display devices having various structures such as twisted nematic (TN) mode liquid crystal display devices, IPS mode liquid crystal display devices, and VA (Vertial alignment) mode liquid crystal display devices.

Hereinafter, a liquid crystal display device and a method for manufacturing the same according to the present invention will be described in detail with reference to the accompanying drawings. In the following description, the IPS mode liquid crystal display device will be described as an example of the present invention. However, this is for convenience of description and the present invention is not limited to the liquid crystal display device having a specific structure but is applicable to the liquid crystal display device having various structures.

4A to 4D are diagrams illustrating a method of manufacturing an IPS mode liquid crystal display device according to the present invention. In this case, for convenience of description, the drawings are divided into pixel areas and pad areas.

First, as shown in FIG. 4A, a metal such as Cu, Mo, Ta, Cr, Ti, Al, or Al alloy is evaporated in the pixel region of the first substrate 120 made of a transparent insulating material such as glass. Or stacked by a sputtering method and etched with an etchant to form the gate electrode 111 and the plurality of common electrodes 105. Subsequently, after the insulating layer 122 is formed over the entire first substrate 120, the semiconductor layer 112 is formed by laminating and etching a semiconductor material such as a-Si and n ⁺ a-Si in the pixel region. . Thereafter, metals such as Cr, Mo, Cu, Ta, Ti, Al, or Al alloys are stacked and etched on the semiconductor layer 112 by deposition or sputtering to form a source electrode 113 and a drain electrode 114. As a result, a thin film transistor is formed and a plurality of pixel electrodes 107 are formed of the same metal as the source electrode 113 and the drain electrode 114 in the pixel region. At this time, the pad 108 is formed in the pad area.

Subsequently, as shown in FIG. 4B, a protective layer 124 made of a transparent organic material is stacked on the first substrate 120. The organic material may be BCB (Benzo Cyclo Butene), photoacryl, polyimide, cellulose, plastic, epoxy resin, or the like. Thereafter, as shown in FIG. 4C, the metal layer 129 is formed on the pad 108 in the pad region. The metal layer 129 is to prevent the pad 108 from being opened and oxidized to the outside, and is made of an anisotropic conductive film. By using such an anisotropic conductive film, it is possible to form the anti-oxidation metal layer 129 on the pad 108 without etching the organic protective layer 124 (that is, without using an etching mask).

In addition, the metal layer 129 may be formed on the metal layer 129 without etching the protective layer 124 of the pad region.

5A and 5B illustrate a method of forming the metal layer 129. First, as shown in FIG. 5A, when pressure is applied at a high temperature while the anisotropic conductive film 129a is brought into contact with the organic protective layer 124 formed on the pad 108 of the pad region, the pressure shown in FIG. As described above, the organic protective layer 124 on the pad 108 is dissolved and the anisotropic conductive film 129a is bonded to the pad 108 to form a metal layer 129 on the pad 108. Although not shown in the drawing, the anisotropic conductive film 129a is made of an adhesive and includes a conductive ball therein. Therefore, as the pressure is applied, the anisotropic conductive film 129a is attached to the pad 108, and the conductive balls therein are in contact with each other to be electrically conductive.

Meanwhile, a black matrix 132 is formed on the second substrate 30. The black matrix 132 is formed of Cr / CrOx or black resin, and is formed in the gate line region, the data line region, the thin film transistor region, and the pad region, which are non-display regions, to prevent light from leaking to the non-display regions. . In addition, a color filter layer 134 of R (Red), G (Green), and B (Blue) for real color is formed in the pixel area of the second substrate 130. Although not shown in the drawings, an overcoat layer may be formed on the color filter layer 134 to improve the flatness of the second substrate 130.

As shown in FIG. 4 (d), the first substrate 120 on which the thin film transistor is formed and the second substrate 130 on which the color filter layer 134 is formed are bonded by a sealing material (not shown). The liquid crystal display device is completed by forming a liquid crystal layer 140 by injecting a liquid crystal (liquid crystal injection method) between the first substrate 120 and the second substrate 130. In this case, the liquid crystal layer 140 is not a liquid crystal injection method, but directly drops the liquid crystal onto the first substrate 120 or the second substrate 140 and then the first substrate 120 and the second substrate ( It may be formed by a liquid dispening method in which the liquid crystal is uniformly distributed over the entire substrates 120 and 140 by the bonding of 140.

In the IPS mode liquid crystal display device manufacturing method, the mask for forming the gate electrode 111 and the plurality of common electrodes 105, the source / drain electrodes 113 and 114, the pixel electrode 107 and the pad 108, and the semiconductor A mask for forming the layer 112 is required. In other words, three masks are required. Comparing this with the conventional IPS mode liquid crystal display device, since five masks are used in the conventional IPS mode liquid crystal display device, only three masks are used in the IPS mode liquid crystal display device of the present invention. do. As such, a reduction in the number of masks used means a reduction in the process performed. Therefore, it can be seen that the manufacturing process of the IPS mode liquid crystal display device of the present invention is greatly simplified compared to the conventional IPS mode liquid crystal display device.

In the structure and manufacturing method of the liquid crystal display device of the present invention described above, an IPS mode liquid crystal display device has been described as an example. However, the liquid crystal display device of the present invention is not limited to the liquid crystal display device having a specific structure as described above. For example, the structure of the TN mode liquid crystal display device is similar to that of the IPS mode liquid crystal display device except for the common electrode and the pixel electrode. That is, the structure is similar to that of the IPS mode liquid crystal display device except that the pixel electrode is formed over the entire pixel area on the protective layer and the common electrode is formed on the second substrate to apply an electric field perpendicular to the substrate. The structure of the pad region is also substantially the same as that of the IPS mode liquid crystal display device. Therefore, even in the case of the TN mode liquid crystal display device, it is possible to quickly manufacture the liquid crystal display device by forming a protective layer as an organic protective layer and using an anisotropic conductive film.

In addition, the present invention is not limited to the liquid crystal display device having a specific structure but can be applied to the liquid crystal display device of any structure, and thus may be applied to various manufacturing methods. For example, the IPS mode liquid crystal display device having a common electrode and a pixel electrode formed in a zigzag shape may also be excellently applied to the present invention.

As described above, in the present invention, since the protective layer is formed of an organic material and the anisotropic conductive film is contacted with the organic material to apply a pressure at high temperature to form a pad oxidation prevention metal layer, only three masks for manufacturing a liquid crystal display device are required. Done. Therefore, it is possible to manufacture a liquid crystal display device quickly and to significantly reduce the manufacturing cost.

Claims (20)

A pixel region defined by a gate line and a data line, the pixel region including a plurality of pixels in which a thin film transistor is formed to form an electric field between the pixel electrode and the common electrode; A pad region formed around the pixel region and including a pad for applying an external signal to the pixel region; And A liquid crystal display device made of a conductive film and formed of a metal layer formed on the pad to prevent oxidation of the pad. The liquid crystal display device according to claim 1, wherein the conductive film is an anisotropic conductive film. The method of claim 1, wherein the thin film transistor, A gate electrode formed on the substrate; An insulating layer stacked over the entire substrate on which the gate electrode is formed; A semiconductor layer formed on the insulating layer; A source electrode and a drain electrode formed on the semiconductor layer; And And a protective layer stacked over the entire substrate on which the source and drain electrodes are formed. The liquid crystal display device of claim 3, wherein the protective layer is an organic protective layer. The liquid crystal display device according to claim 4, wherein the organic protective layer is formed on a pad. 6. The liquid crystal display device according to claim 5, wherein the organic protective layer on the pad is removed as the pressure is applied at a high temperature in contact with the conductive film. The liquid crystal display of claim 1, wherein the common electrode and the pixel electrode are formed on a same substrate to generate a transverse electric field. The liquid crystal display device of claim 1, wherein the common electrode and the pixel electrode are formed on different substrates to form an electric field perpendicular to the substrate. A pad formed at an outer portion of the liquid crystal panel; A protective layer laminated on an outer portion of the liquid crystal panel; And Pad portion of the liquid crystal display device composed of a metal layer made of a conductive film formed on the pad. The pad unit of claim 9, wherein the protective layer is an organic protective layer. The pad unit of claim 10, wherein the organic protective layer on the pad is removed as the pressure is applied at a high temperature in contact with the conductive film. The pad part of a liquid crystal display device according to claim 9, wherein the conductive film is an anisotropic conductive film. Preparing a substrate including a pixel region and a pad region; Forming a plurality of gate lines and data lines in the pixel region of the substrate; Forming a plurality of thin film transistors in the pixel region; Forming a pad in the pad area; Forming a protective layer over the substrate; And Forming a metal layer made of a conductive film on the pad. The method of claim 13, wherein the forming of the thin film transistor comprises: Forming a gate electrode in the pixel region on the substrate; Stacking an insulating layer over the substrate; Forming a semiconductor layer over the insulating layer of the pixel region; And And forming a source electrode and a drain electrode on the semiconductor layer. 15. The method of claim 13, further comprising forming a common electrode on the passivation layer of the pixel region to form an electric field substantially perpendicular to the substrate. 15. The method of claim 13, further comprising forming a plurality of common electrodes and pixel electrodes in the pixel region which generate a transverse electric field substantially parallel to the substrate. The method of claim 16, wherein the common electrode is formed at the same time as the gate electrode. The method of claim 16, wherein the pixel electrode is formed at the same time as the source electrode and the drain electrode. The method of claim 13, wherein the protective layer is an organic protective layer. The method of claim 13, wherein the forming of the metal layer comprises: Applying heat to the protective layer; And And applying pressure in the state in which the conductive film is in contact with the protective layer to melt the protective layer on the pad and simultaneously attaching the conductive film to the pad.

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