KR20040056667A - In-Plane Switching mode Liquid crystal display device and method for fabricating the same - Google Patents

Abstract

PURPOSE: An array substrate for an IPS(In Plane Switching) mode LCD(Liquid Crystal Display) and a manufacturing method thereof are provided to control the shape and height of a common electrode and a pixel electrode and then forming them at the same layer, thereby capable of driving them with a low driving voltage, without narrowing the width of the electrodes. CONSTITUTION: A gate insulation layer(133) is formed on a substrate(120). A data wire(138) is formed on the substrate(120) of a semiconductor layer. A passivation layer(145) is formed on source/drain electrodes. An organic insulation material is coated on the entire surface of the passivation layer(145) and thereafter organic film patterns(147) are formed at the regions for forming a common electrode(150) and a pixel electrode(153) by a mask process. Because the common electrode(150) and the pixel electrode(153) are formed on the organic film pattern(147) having a semicircle or a triangle shape, there cross sections have a constant angle, an inclined shape or a curved shape.

Description

In-Plane Switching mode Liquid crystal display device and method for fabricating the same

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film transistor liquid crystal display, and more particularly, to change the cross-sectional shape of a common electrode and a pixel electrode and to form a high cross-sectional height to reduce a driving voltage applied to a transverse electric field. The present invention relates to an array substrate for a liquid crystal display device.

Recently, liquid crystal displays have been spotlighted as next generation advanced display devices having low power consumption, good portability, technology-intensive, and high added value.

The liquid crystal display injects liquid crystal between an array substrate including a thin film transistor (TFT) and a color filter substrate, and obtains an image effect by using a difference in refractive index of light according to anisotropy of the liquid crystal. Means an image display device by a non-light emitting element.

The structure of the liquid crystal molecules is thin and long, and the arrangement direction of the liquid crystal molecules is controlled by an appropriately applied voltage, that is, the alignment direction of the liquid crystal molecules is arbitrarily changed to change the molecular arrangement of the liquid crystal, thereby polarizing the optical anisotropy of the liquid crystal. The desired image information is expressed by arbitrarily modulating the light.

At this time, the electrode for applying a voltage to the liquid crystal is a common electrode located on the color filter substrate and the pixel electrode located on the array substrate, when the voltage is applied to these two electrodes, the upper and lower sides formed by the difference of the applied voltage The method of controlling the direction of the liquid crystal molecules in which the vertical electric field is located is mainly used.

However, when the liquid crystal is driven by the vertical electric field generated by the common electrode and the pixel electrode vertically formed as described above, the characteristics such as transmittance and aperture ratio are excellent, but the viewing angle characteristics are not excellent. . In order to overcome this problem, a liquid crystal driving method using an in-plane switching (IPS) method using a horizontal electric field has been proposed.

The above-described transverse electric field type liquid crystal display device will be described with reference to FIG.

In a general liquid crystal panel of a transverse electric field type liquid crystal display device, a color filter substrate 1 having a color filter and a thin film transistor array substrate 5 face each other, and a liquid crystal 15 is disposed between the two substrates 1 and 5. Formed. At this time, the common electrode 7 and the pixel electrode 9 are formed on the same plane on the thin film transistor array substrate 5, and the horizontal electric field 12 is formed according to the voltage applied thereto. The liquid crystal molecules 15 between the electric fields 12 are driven by the influence thereof.

2A to 2C, the operation of the liquid crystal molecules in the voltage on and off states will be briefly described.

2A and 2B are cross-sectional views and plan views showing the state of liquid crystal molecules in an off state without voltage application of the transverse electric field type liquid crystal display device.

As shown in FIG. 2A, since no voltage is applied, no horizontal electric field is formed between the common electrode 7 and the pixel electrode 9, and no change occurs in the state of the liquid crystal molecules 15.

Referring to FIG. 2B, when a voltage is applied to form a horizontal magnetic field between the common electrode 7 and the pixel electrode 9, the liquid crystal molecules 15 positioned between the two electrodes rotate in a predetermined direction.

2C is a cross-sectional view illustrating the operation of liquid crystal molecules in a voltage on state of a transverse electric field type liquid crystal display device. Although the state of the liquid crystal molecules 15a at positions corresponding to the common electrode 7 and the pixel electrode 9 is unchanged, the liquid crystal molecules 15a positioned between the common electrode 7 and the pixel electrode 9 are the common electrodes. Due to the horizontal electric field 12 formed by the voltage application of 7 and the pixel electrode 9, the horizontal electric field 12 is changed to the same direction as the horizontal electric field 12.

As described above, since the liquid crystal is driven by a horizontal electric field, the transverse electric field type liquid crystal display device has a viewing angle characteristic that can be viewed up to about 80 to 85 ° in the up, down, left, and right directions when the user views the displayed screen from the front. .

Next, the array substrate for a transverse electric field type liquid crystal display device is demonstrated with reference to FIG.

FIG. 3 is a plan view showing a plane of one pixel portion of a lower substrate for a general transverse electric field type liquid crystal display device, and illustrations of the gate and data pad portions are omitted.

As shown in the drawing, a gate wiring 21 including a gate electrode 23 is formed in a first direction, intersects with the gate wiring 21 in a second direction, and includes a data wiring including a source electrode 38. A 35 is formed, and the drain electrode 41 is formed to be spaced apart from the source electrode 38 at a predetermined interval. The source electrode 38 and the drain electrode 41 are formed between the source electrode 38 and the drain electrode 41. An island-shaped semiconductor layer 32 is formed to overlap the drain electrode 41 at predetermined intervals, and the thin film includes the gate electrode 23, the semiconductor layer 32, and the source and drain electrodes 38 and 41. This is called a transistor (T).

In addition, a common wiring 26 is formed in the first direction, and a plurality of common electrodes 28 are branched in the second direction in the common wiring 26.

A drawing wiring 43 extending from the drain electrode 41 is formed in the first direction, and a plurality of pixel electrodes 45 are formed in the second direction in the drawing wiring 43. Are divergently branched.

4 and 5 are cross-sectional views of the array substrate according to AA ′ and BB ′ of FIG. 3.

As shown in FIG. 4, which is a cross-sectional view taken along the line A-A ', a gate insulating film 26 and a gate insulating film 26 over the gate electrode 23 and the gate electrode 23 on the substrate 20. The ohmic contact layer 32b and the ohmic contact layer 32b formed to be spaced apart from the active layer 32a and the active layer 32a by contacting the ohmic contact layer 32b are formed by exposing the active layer 32a and spaced apart from each other. Source and drain electrodes 38 and 41 are formed, and a thin film transistor is formed including the gate electrode 23, the semiconductor layer 32, and the source and drain electrodes 38 and 41. A protective layer 48 made of an inorganic insulating material is formed on the source and drain electrodes 38 and 41.

As shown in FIG. 5, which is a cross-sectional view taken along line B-B 'of the pixel region, a material forming the gate electrode 23 when the gate electrode 23 is formed in the thin film transistor of FIG. 4 on the substrate 20. The common electrode 28 and the gate insulating layer 26 formed on the common electrode 28 and the data line 35 and the pixel electrode 45 are formed on the common electrode 28. A protective layer 48 made of an inorganic insulating material is covered on the data line 35 and the pixel electrode 45.

In the above-described configuration of an array substrate of a transverse electric field type liquid crystal display device, the shape of two voltages, namely, the common electrode 28 and the pixel electrode 45, which cause the state change of the liquid crystal molecules, has a rectangular cross section. .

In the transverse electric field type liquid crystal display device having the above structure, as the electrode spacing is reduced, more electrode patterns are entered in one pixel, so that the aperture ratio decreases. On the contrary, when the electrode spacing is increased, the distance between the common electrode and the pixel electrode becomes far and wide. The generated electric field becomes weak and the liquid crystal does not work. In order to operate this, a high driving voltage is required.

In addition, when a driving voltage is applied to the common electrode and the pixel electrode, an electric field is generated between the two electrodes, but the electric field has a disadvantage in that the strength of the electric field decreases toward the upper substrate.

6A to 6B are diagrams simulating the movement of liquid crystal according to a driving voltage in a conventional transverse electric field liquid crystal display device.

As shown in FIG. 6A, 4V is applied and FIG. 6B is 5V. As shown in FIG.

However, if the driving voltage is increased to improve the liquid crystal characteristics, the power consumption increases, resulting in a problem such as increased battery consumption in the notebook computer, and also goes against the liquid crystal display device for low power consumption.

The present invention has been made to solve the above-described problems, and by forming the same layer by appropriately adjusting the cross-sectional shape and height of the common electrode and the pixel electrode, it is possible to drive at a low driving voltage without narrowing the electrode spacing. The first object of the present invention is to provide an array substrate for a transverse electric field type liquid crystal display device with low power consumption, and to form a wide inter-electrode gap when the driving voltage is not lowered. It is a second object to provide an array substrate for use.

1 is a cross-sectional view showing a cross section of a part of a general transverse electric field type liquid crystal display device;

2A and 2B are a cross-sectional view and a plan view showing an operation of an off state of a general transverse electric field type liquid crystal display device.

2C is a cross-sectional view illustrating an operation of an on state of a general transverse electric field type liquid crystal display device.

3 is a plan view of one pixel unit of a general transverse electric field type liquid crystal display device;

4 and 5 are cross-sectional views of liquid crystal displays according to AA ′ and B-B ′ of FIG. 3.

6A and 6B are diagrams simulating the movement of a liquid crystal when a driving voltage of 4V and 5V is applied to a transverse electric field type liquid crystal display having a conventional electrode structure.

7A to 7C are cross-sectional views illustrating electrode structures of the transverse electric field type liquid crystal display device according to the present invention.

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

9A to 9D and 10A to 10D and 11A to 11D are cross-sectional views taken along the line X-X ', Y-Y', and Z-Z 'of FIG.

12A and 12B are diagrams simulating the movement of liquid crystals when the driving voltages of 3V and 4V are applied to a transverse electric field type liquid crystal display having an electrode structure according to the present invention.

<Description of the symbols for the main parts of the drawings>

120 substrate 133 gate insulating film

138: data wiring 147: organic film pattern

150: common electrode 153: pixel electrode

In order to achieve the above object, the array substrate for a transverse electric field type liquid crystal display device according to the present invention comprises a transparent insulating substrate; A plurality of gate wires configured to be spaced apart from each other and parallel to each other in one direction of the substrate; A common wiring configured to be spaced in parallel with the gate wiring; A plurality of data lines defining pixel regions crossing the gate lines; A thin film transistor configured at an intersection point of the gate line and the data line; A plurality of common electrodes contacted through the common electrode contact hole in the common wiring and formed on the organic layer pattern and branched to the pixel region; The thin film transistor is connected to the thin film transistor through a drain contact hole, and alternately formed with the common electrode, and includes a plurality of pixel electrodes formed on an organic layer pattern.

The material forming the common electrode and the pixel electrode is made of a material selected from chromium, aluminum, indium tin oxide, and indium zinc oxide, and is formed on the same layer.

In addition, the organic film pattern is composed of an organic material of acrylic resin or benzocyclobutene, the cross section of the organic film pattern is characterized in that the triangular or semi-circular.

In addition, the heights of the common electrode and the pixel electrode include a height of 1 μm to 3 μm, including the height of the lower organic layer pattern, and preferably 2 μm.

According to an aspect of the present invention, there is provided a method of fabricating an array substrate for a transverse electric field type liquid crystal display device, the method comprising: forming a plurality of gate wires parallel to each other in a first direction on a transparent insulating substrate; Forming a common wiring spaced apart in parallel with the gate wiring; Forming data lines in a plurality of second directions defining a pixel region crossing the gate lines; Forming a thin film transistor at an intersection point of the gate line and the data line; Forming an organic layer pattern on the thin film transistor; Forming a common electrode connected through the common wiring and the contact hole on the organic layer pattern, and a plurality of pixel electrodes intersecting the common electrode.

Hereinafter, it will be described in detail through a preferred embodiment of the present invention.

In a transverse electric field type liquid crystal display device, a liquid crystal is horizontally operated on a substrate by a common electrode and a pixel electrode formed on an array substrate, which is a lower substrate. Therefore, the electrode structure for operating the liquid crystal is to form the common electrode 105 and the pixel electrode 110 to have a height equal to the thickness of the cell gap (d) of the liquid crystal panel as shown in FIG. However, when the common electrode 105 and the pixel electrode 110 are formed as described above, they are not realistic due to process problems and liquid crystal injection. In this case, the liquid crystal layer may be formed by a dropping method of forming a liquid crystal layer after bonding the two substrates by dropping the liquid crystal onto the lower substrate or the upper substrate rather than the conventional injection method.

In the exemplary embodiment of the present invention, as shown in FIGS. 7B to 7C, the cross-section has a semicircular or triangular shape, and after the organic layer patterns 113 and 114 are formed on the same layer, the organic layer pattern 113 The common electrodes 115 and 116 and the pixel electrodes 117 and 118 are formed on the upper and lower portions 114 and 114.

8 is a plan view showing a plane of one pixel portion of an array substrate for a transverse electric field type liquid crystal display device according to an embodiment of the present invention.

As shown in the figure, the gate wiring 123 in the first direction and the data wiring 138 in the second direction cross each other to define a pixel area, and the gate wiring 123 and the gate wiring 138 intersect with the data wiring 138 at the intersection. A thin film transistor T, which is a switching element connected to the 123 and the data line 138, is formed. The common wiring 130 extending in the first direction is formed in the pixel region P, and the plurality of common electrodes 150 connected to and branched from the common wiring 130 through the common wiring contact hole 160 are formed. It extends in two directions. In addition, in the pixel region P, a plurality of pixel electrodes 153 are arranged to be alternately spaced apart from the common electrode 150 in a second direction. The pixel electrode 153 is formed of a thin film transistor T and a drain. It is connected through the contact hole 149. In this case, an organic layer pattern 147 is formed under the common electrode 150 and the pixel electrode 153, and a common electrode 150 and a pixel electrode 153 are formed on the organic layer pattern 147.

9A to 9D, 10A to 10D, and 11A to 11D are step-by-step manufacturing process diagrams according to X-X ', Y-Y', and Z-Z 'of an array substrate for a transverse electric field liquid crystal display according to the present invention.

As shown in FIGS. 9A, 10A, and 11A, a metal material such as aluminum (Al), an aluminum alloy (AlNd), or molybdenum (Mo) is deposited on the transparent insulating substrate 120, followed by a mask process. The gate wiring 123 and the common wiring 130 are formed by including the gate electrode 126. Thereafter, an inorganic insulating material such as silicon oxide (SiO ₂ ) or silicon nitride (SiNx) is deposited on the entire surface of the substrate 120 on which the gate electrode 126 and the common wiring 130 are formed to form a gate insulating layer 133.

Next, as illustrated in FIGS. 9B, 10B, and 11B, amorphous silicon (a-Si) is deposited on the substrate 120 on which the gate insulating layer 133 is formed, and a mark process is performed to form an active layer 135a and an ohmic. The semiconductor layer 135 of the contact layer 135b is formed.

Next, as shown in FIGS. 9C, 10C, and 11C, a metal material such as chromium (Cr) is deposited on the substrate 120 on which the semiconductor layer 135 is formed to form a data line 138 and the data line ( The drain electrode 143 is formed to be spaced apart from the source electrode 140 branched from 138. The protective layer 145 is formed by depositing silicon oxide (SiO ₂ ), silicon nitride (SiNx), or the like on the source and drain electrodes 140 and 143 spaced apart from each other with the gate electrode 126 interposed therebetween.

Next, as shown in FIGS. 9D, 10D, and 11D, an organic insulating material such as acryl-based resin or benzocyclobutene (BCB) is coated on the protective layer 145 on the entire surface, and then a mask process is performed. The organic layer pattern 147 is formed where the common electrode 150 and the pixel electrode 153 are to be formed. The cross-section of the organic layer pattern 147 may be formed in a triangular or semi-circular shape, and the side surface may have a predetermined angle, or may be curved. In addition, the height of the organic layer pattern 147 may be 1 μm to 3 μm including the thickness of the common electrode 150 or the pixel electrode 153 to be formed on the organic layer pattern 147. It is formed to a height of 탆.

Subsequently, a mask process is performed on the substrate 120 on which the organic layer pattern 147 is formed to expose the drain electrode 143 and the common wiring 130 on the protective layer 145. And a common wiring contact hole 160 is formed. This is to connect the drain electrode 143 and the pixel electrode 153, and connect the common electrode 130 and the common electrode 150 formed on the organic layer pattern 147.

Next, as shown, a metal material, for example, the same as the material forming the gate electrode 126 or the data line 138, is formed in the substrate 120 on which the drain contact hole 149 and the common wiring contact hole 160 are formed. After depositing aluminum (Al), aluminum alloy (AlNd), molybdenum (Mo), chromium (Cr) or transparent metallic materials such as indium-tin-oxide (ITO) and indium-zinc-oxide (IZO) The mask process is performed to form the common electrode 150 and the pixel electrode 153 on the same layer. Since the cross-sectional shape of the common electrode 150 and the pixel electrode 153 is formed on the semi-circular or triangular organic layer pattern 147, the side surface has a predetermined angle and forms an inclined or curved surface.

As described above, when an array substrate for a transverse field type liquid crystal display device including an organic film pattern in the same layer and having a triangular or semicircular common electrode and pixel electrode structure having a height of 1 μm to 3 μm is formed, the common electrode and Since the electric field of the horizontal component of the electric field between the pixel electrodes has the effect of increasing, the response speed characteristics are improved, the response of the liquid crystal according to the electric field is improved, it is possible to lower the driving voltage. Alternatively, the aperture ratio may be increased by forming a wide gap between the electrode and the electrode.

12A and 12B illustrate simulations according to driving voltages of a liquid crystal display device in which protrusions (triangles or semicircles) of electrodes according to the present invention are formed.

As shown, 3V and 4V were applied, but it is shown that they are in contrast with FIGS. 6A and 6B, which are simulation drawings in which 4V and 5V are applied with conventional electrode structures, respectively. Although the electrode width and the distance between electrodes were formed at the same interval, the simulation result shows the same result even though the driving voltage was lowered by 1V. That is, the electrode configuration of the triangular and semi-circular structure has the effect of widening the electrode compared to the conventional electrode structure, which is effective for driving the liquid crystal, the horizontal component of the electric field is increased, the response speed characteristics are improved.

As a result of the foregoing, when the protrusion structure is applied, the aperture ratio can be improved by forming a wide interval between electrodes.

In the transverse electric field type liquid crystal display device in which a triangular or semi-circular protrusion structure electrode is formed, the intensity of the electric field decreases from the array substrate to the top plate which is the color filter substrate. It has the effect of improving the response speed by increasing the horizontal component, and also can lower the driving voltage when forming the electrode at the same interval as before, and when the driving voltage is the same, by forming the electrode interval wider than the conventional opening ratio There is an effect to improve.

Claims (8)

A transparent insulating substrate; A plurality of gate lines configured to be spaced apart from each other and parallel to each other in a first direction of the substrate; A common wiring configured to be spaced in parallel with the gate wiring; A plurality of data lines arranged in a second direction crossing the gate lines to define a pixel area; A thin film transistor configured at an intersection point of the gate line and the data line; A plurality of common electrodes contacted through the common electrode contact hole in the common wiring and formed on the organic layer pattern and branched to the pixel region; A plurality of pixel electrodes connected to the thin film transistor through a drain contact hole and intersected with the common electrode and formed on an organic layer pattern Array substrate for a transverse electric field type liquid crystal display device comprising a. The method of claim 1, And the material forming the common electrode and the pixel electrode is one selected from chromium, aluminum, indium tin oxide, and indium zinc oxide. The method of claim 1, And the common electrode and the pixel electrode are formed on the same layer. The method of claim 1, And the organic layer pattern is formed of an organic resin such as acrylic resin or benzocyclobutene. The method of claim 1, And a cross section of the organic layer pattern is a triangular or semi-circular shape. The method of claim 1, And the heights of the common electrode and the pixel electrode are in the range of 1 μm to 3 μm, including the height of the lower organic layer pattern. The method of claim 6, And a height of the organic layer pattern is 2 μm. Forming a plurality of gate wires in parallel with each other in a first direction on a transparent insulating substrate; Forming a common wiring spaced apart in parallel with the gate wiring; Forming data lines in a plurality of second directions defining a pixel region crossing the gate lines; Forming a thin film transistor at an intersection point of the gate line and the data line; Forming an organic layer pattern on the thin film transistor; Forming a common electrode connected to the common wiring and the contact hole on the organic layer pattern, and a plurality of pixel electrodes that are alternately formed with the common electrode; Method of manufacturing an array substrate for a transverse electric field type liquid crystal display device comprising a.