KR19990052411A - Manufacturing method of liquid crystal display device - Google Patents

Abstract

The present invention discloses a method of manufacturing a liquid crystal display device in an in-plane switching (IPS) mode. In this method, a pixel electrode and an opposite electrode are formed on the same transparent substrate, and a thin film transistor for switching the pixel electrode is applied to a liquid crystal display device formed on the substrate, and on top of the transparent insulating substrate, Forming a protective film pattern coated with a photosensitive film; Depositing a transparent conductive material in a predetermined thickness on the entire surface of the substrate; And removing the photosensitive layer and the transparent conductive material on the protective layer.

Description

Manufacturing method of liquid crystal display device

The present invention relates to a method for manufacturing a liquid crystal display device, and more particularly, to a method for manufacturing an in-plane switching mode liquid crystal display device in which a pixel electrode and an opposite electrode are formed on the same substrate.

In general, in display elements such as notebook computers, televisions, and graphic displays, a liquid crystal display panel for realizing an image includes a pair of transparent glass substrates and liquid crystal enclosed between the glass substrates. A panel having a structure in which a pixel electrode and a switching element such as a thin film transistor for switching the pixel electrode is formed on at least one of the glass substrates, and a color filter and a counter electrode are formed on the other opposing one. Recently, a liquid crystal of a TN mode (Twist nematic mode) is used as a liquid crystal which is widely used, and the liquid crystal display device in which the liquid crystal of the TN mode is used is a vertical applied to the pixel electrode of the lower substrate and the pixel electrode of the upper substrate. Since the liquid crystal is operated by the electric field, the viewing angle is narrow.

In order to solve the viewing angle problem described above, a liquid crystal display device having an in-plane switching mode (hereinafter referred to as IPS mode) using a parallel field has been proposed.

FIG. 1 shows a unit pixel area formed on the lower glass substrate of the liquid crystal display device in the IPS mode and the peripheral portion thereof.

Referring to FIG. 1, the liquid crystal display of the IPS mode includes a main portion of the pixel electrode 4 in parallel with the scan line 2 at a position separated from the scan line (or gate line 2) by a predetermined interval on the lower substrate. (main) line (hereinafter referred to as first main line: 4a) is formed, and a plurality of branches (hereinafter referred to as first branches: 4b) vertically branched from the main line 4a are formed, These first branches 4b are separated from each other at predetermined intervals and arranged in parallel with each other. The first branches 4b of the pixel electrode 4 are separated from the first branches 4b at predetermined intervals and are branches parallel to the first branches (hereinafter, referred to as second branches). Referred to as: 6b). The second branches 6b branch from a main line (hereinafter referred to as a second main line 6a) formed in parallel with the scan line 2, and the second main line 6a is connected to the scan line 2. It is formed on the common electrode bus line 8 which is separated and arranged in parallel at a predetermined interval, and is electrically connected to the common electrode bus line 8 under the insulating film through a contact hole formed in the insulating film 10 below. Therefore, a voltage for generating a parallel electric field is applied from the common electrode bus line 8. Meanwhile, the pixel electrode 4 is electrically connected to the thin film transistor 12 to receive a voltage for generating a parallel electric field.

Since the pixel electrode 4 and the counter electrode 6 are formed on the same lower substrate 5, when a voltage is applied to the pixel electrode 4 and the counter electrode 6 of the liquid crystal display device, a horizontal electric field is applied. Is generated. Liquid crystals having negative dielectric anisotropy by application of a horizontal electric field are arranged in a direction perpendicular to the direction of the electric field and inclined at 45 degrees to the polarization direction, thereby becoming a bright state.

However, in the liquid crystal display of the IPS mode, the parallel electric field generated by the first branches 4a of the pixel electrode 4 and the second branches 6a of the counter electrode 6 may be generated by the first and the second. The liquid crystals between the two branches 4a, 6a and on top of the edge portion align, but fail to align the liquid crystals above their respective center portions. This results in a problem of lowering of transmittance. In order to solve this problem, a method of forming a very narrow gap between the first branches 4a and the second branches 4b such as 3-4 μm is used.

However, this method also has a problem that the first branches 4a of the pixel electrode 4 and the second branches 6a of the opposite electrode 6 adjacent to each other short during the process as the gap between the pixel electrode and the counter electrode becomes narrow. This may occur.

Accordingly, the present invention has been made to solve the above-described problems, and when the gap between the pixel electrode and the counter electrode is narrowed, the manufacturing of a liquid crystal display device which can prevent the short circuit occurring between the pixel electrode and the adjacent counter electrode. The purpose is to provide a method.

1 is a schematic plan view of a unit pixel area and a peripheral portion of a liquid crystal display in an in-plane switching mode;

2A to 2F are cross-sectional views illustrating a method of manufacturing a liquid crystal display device according to an embodiment of the present invention.

3A to 3F are cross-sectional views illustrating a method of manufacturing a liquid crystal display device according to another embodiment of the present invention.

(Explanation of symbols for the main parts of the drawing)

20, 20a, 20b: ITO film 22: insulating layer

24: protective film 26, 30: photosensitive film

26a, 30a: Photoresist pattern 28: Mask

28a: transparent portion of the mask 28b: opaque portion of the mask

In order to achieve the above object of the present invention, in the method of manufacturing a liquid crystal display device according to an aspect of the present invention, a pixel electrode and a counter electrode are formed on the same transparent substrate, and a thin film transistor for switching the pixel electrode. Is applied to the liquid crystal display device formed on the substrate, and forming a protective film pattern on which a photosensitive film is applied on the transparent insulating substrate; Depositing a transparent conductive material in a predetermined thickness on the entire surface of the substrate; And removing the photosensitive layer and the transparent conductive material on the protective layer.

According to another aspect of the present invention, there is provided a method of manufacturing a liquid crystal display device, wherein a pixel electrode and a counter electrode are formed on the same transparent substrate, and a thin film transistor for switching the pixel electrode is applied to the liquid crystal display device formed on the substrate. Forming a common electrode wiring on the transparent insulating substrate; Forming an insulating layer on the substrate including the common electrode wiring; Forming a protective film on the insulating layer; Forming a photoresist mask pattern separated by a predetermined interval on the passivation layer; Etching away the exposed portion of the protective film; Depositing a transparent conductive material in a predetermined thickness on the entire surface of the substrate; And stripping the photoresist mask pattern to remove the photoresist mask pattern and a transparent conductive material thereon, wherein the odd-numbered layers of the transparent conductive films formed on the insulating film between the passivation layers are pixel electrodes. The second films are opposite electrodes, and the pixel electrode is electrically connected to the switching element, and the opposite electrode is formed to be electrically connected to the common electrode wiring.

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

2A to 2F are flowcharts illustrating a method of manufacturing a liquid crystal display device according to an exemplary embodiment of the present invention.

Referring to FIG. 2A, a substrate in which an insulating layer 22 and a passivation layer 24 are sequentially stacked is provided on a transparent insulating substrate (not shown) such as a glass substrate. Although not shown in the drawing, a scanning line, a common electrode bus line, a thin film transistor, and the like are already formed on the provided substrate. Then, a photosensitive film 26 of a predetermined thickness is applied over the protective film 24. The protective film 24 formed on the substrate is preferably formed to a thickness of 2,000 mPa or more.

Referring to FIG. 2B, a mask 28 composed of a transparent portion 28a and an opaque portion 28b is aligned on top of the photosensitive film 26, and light of a specific wavelength is incident to expose the photosensitive film 26. . The photosensitive film used in the present embodiment is a positive photoresist in which the exposed portion is removed by the developing solution. During the exposure process, the photosensitive film located below the transparent portion 28a of the mask 28 is exposed. Thereafter, a developing process of dipping the substrate including the exposed photosensitive film 26 in a developing solution to remove the exposed portion is performed. The state after the above-mentioned developing process is completed is shown in FIG. 2C. As shown in Fig. 2C, the protective film 24 located between the photosensitive film patterns 26a is exposed. Portions between the photoresist pattern 26a are portions in which the pixel electrode and the counter electrode are to be formed in a subsequent process, and the width thereof is 3-4 탆.

Next, referring to FIG. 2D, the exposed portion of the protective layer 24 is etched and removed. In this case, as the etching method used, plasma etching, which is a kind of dry etching method, may be used, and a wet etching method of selectively etching only the exposed protective film may be used, but dry etching method may be used for accurate pattern formation. It is more preferable.

Next, referring to FIG. 2E, a transparent conductive material 20 is deposited on the entire surface of the substrate on which the exposed protective film is etched. Indium Tin Oxide (hereinafter referred to as ITO) is preferably used as the transparent conductive material described above, and the thickness thereof is preferably 500 Pa or less. As the vapor deposition method thereof, it is preferable to use a chemical vapor deposition method. The ITO film 20 is formed on the exposed portion of the insulating layer 22 and on the photoresist pattern 26a by the above deposition process. In the above deposition process, the pattern in the odd order from the direction on the selected X-axis is in contact with the drain of the thin film transistor, and the pattern in the even number is in contact with the common electrode bus line. In addition, if the contact order is alternately performed, it is also possible to contact the odd-numbered pattern with the common electrode bus line and the even-numbered pattern with the drain of the thin film transistor.

Referring to FIG. 2F, a strip process of removing the photoresist film is performed to remove the photoresist pattern 26a. During the stripping process described above, the ITO film 20 on the photoresist pattern 26a is removed together with the photoresist pattern 26a, so that a separate process for removing it is not necessary. As a result of the above processes, the ITO electrode 20a formed at the odd number becomes the pixel electrode, and the ITO electrode 20b formed at the even number becomes the counter electrode.

By forming the pixel electrode 20a and the counter electrode 20b according to the above process sequence, a short circuit problem between the pixel electrode 20a and the counter electrode 20b can be prevented.

3A to 3F are flowcharts illustrating a method of manufacturing a liquid crystal display device according to another exemplary embodiment of the present invention.

The method of the present embodiment differs from the previous embodiment in that a negative photoresist 30 is used in which the unexposed portions are removed from the developing solution. Thus, referring to FIGS. 3B and 3C, the photosensitive film under the opaque portion 28a of the mask 28 remains after the developing process by the exposure process, resulting in the photosensitive film pattern 30a. As shown in Figs. 3D to 3F, the process after the photosensitive film pattern forming step proceeds in the same manner as in the foregoing embodiment, and thus the description thereof is omitted here.

Referring to FIG. 3F, as a result of the above-described processes, the ITO electrode 20a formed at the odd number is the pixel electrode, and the ITO electrode 20b formed at the even number is the counter electrode.

In the case of the present embodiment, if the contact order is alternately performed, the odd-numbered ITO electrodes are opposed to each other by contacting the odd-numbered pattern with the common electrode bus line and the even-numbered pattern with the drain of the thin film transistor. As the electrode, a method of forming the even-numbered ITO electrode by the pixel electrode is also possible. By forming the pixel electrode 20a and the counter electrode 20b according to the above process sequence, a short circuit problem between the pixel electrode 20a and the counter electrode 20b can be prevented.

Meanwhile, after the pixel electrode and the counter electrode patterns are formed, the alignment layer is formed on the uppermost surface of the substrate, in which case, the pretilt angle of the alignment layer is preferably 4 degrees or less. When driving the completed liquid crystal display panel according to the above conditions, the liquid crystal is aligned in the range of 0 to 45 degrees by rubbing of the parallel field and the alignment film generated by the voltage applied to the pixel electrode and the counter electrode. In addition, the transmittance can be maximized by making the product of the thickness of the liquid crystal layer and the anisotropic refractive index be in the range of 0.2-0.6 μm.

As described above, the present invention forms the pixel electrode and the counter electrode as the same material by a photolithography method using a photosensitive film pattern, thereby preventing a short circuit problem between adjacent pixel electrodes and the counter electrode. As a result, the failure rate of the liquid crystal display device can be lowered, thereby improving the reliability.

Meanwhile, although specific embodiments of the present invention have been described and illustrated, modifications and variations can be made by those skilled in the art. Accordingly, the following claims are to be understood as including all modifications and variations as long as they fall within the true spirit and scope of the present invention.

Claims (11)

In the method of manufacturing a liquid crystal display device wherein a pixel electrode and an opposite electrode are formed on the same transparent substrate, and a switching element for switching the pixel electrode is formed on the substrate. Forming a common electrode wiring on the light transmitting substrate; Forming an insulating layer on the substrate including the common electrode wiring; Forming a protective film pattern coated with a photosensitive film on the insulating layer; Depositing a transparent conductive material in a predetermined thickness on the entire surface of the substrate; And And removing the photosensitive layer and the transparent conductive material on the passivation layer, wherein the odd-numbered layers of the transparent conductive layers formed on the insulating layer between the passivation layers are pixel electrodes, and the even-numbered layers are opposite electrodes. And an electrode is electrically connected to the switching element, and the counter electrode is electrically connected to the common electrode wiring. The method of claim 1, wherein the forming of the protective layer pattern comprises: depositing a protective layer on the insulating layer; Applying a photoresist film on top of the protective film; Exposing the photoresist to form a photoresist mask pattern; And removing the protective film of the exposed portion by removing the photoresist. The method of manufacturing a liquid crystal display device according to claim 2, wherein the photosensitive film is a positive photosensitive film from which an exposed portion is removed by development. The method of claim 2, wherein the photosensitive film is a negative photosensitive film from which an unexposed portion is removed by development. The method of claim 1, wherein the removing of the photosensitive film and the transparent conductive material is performed by stripping the photosensitive film on the protective film. The method of claim 1, wherein the switching element is a thin film transistor. The method of claim 1, wherein the transparent conductive material is indium tin oxide. The method of claim 1, wherein the protective film is formed to a thickness of 2000 GPa or more. The method of claim 1, wherein widths of the counter electrode and the pixel electrode are formed to be 3 to 4 µm, respectively. In the method of manufacturing a liquid crystal display device wherein a pixel electrode and an opposite electrode are formed on the same transparent substrate, and a thin film transistor for switching the pixel electrode is formed on the substrate. Forming a common electrode wiring on the transparent substrate; Forming an insulating layer on the substrate including the common electrode wiring; Forming a protective film on the insulating layer; Forming a photoresist mask pattern separated by a predetermined interval on the passivation layer; Etching away the exposed portion of the protective film; Depositing a transparent conductive material in a predetermined thickness on the entire surface of the substrate; And Stripping the photoresist mask pattern to remove the photoresist mask pattern and the transparent conductive material thereon, wherein the odd-numbered layers of the transparent conductive films formed on the insulating film between the passivation layers are pixel electrodes, and the even second Wherein the films are opposite electrodes, wherein the pixel electrode is electrically connected to the switching element, and the opposite electrode is electrically connected to the common electrode wiring. The method of claim 10, wherein the transparent conductive material is indium tin oxide.