KR20120107269A - Liquid crystal display device and method for fabricating the same - Google Patents

Abstract

PURPOSE: A liquid crystal display device and a manufacturing method thereof are provided to laminate an inorganic insulating film and an organic insulating film by a first protection film, thereby guaranteeing a source electrode, a drain electrode, and the protection film are in contact with each other, and reducing the load on a common electrode. CONSTITUTION: A second contact hole selectively eliminates only a second protection film. The second contact hole exposes a pixel electrode. A connection electrode(280b) is formed on the second protection film. The connection electrode connects a drain electrode with the pixel electrode by a first contact hole and the second contact hole. A common electrode(280a) is formed on the same layer as the connection electrode. The common electrode forms a fringe electric field with the pixel electrode.

Description

Liquid crystal display and its manufacturing method {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 liquid crystal display device, and more particularly, to a liquid crystal display device and a manufacturing method thereof capable of improving image quality and reducing power consumption of the liquid crystal display device.

(PDP), Electro Luminescent Display (ELD), Vacuum Fluorescent (VFD), and the like have been developed in recent years in response to the demand for display devices. Display) have been studied, and some of them have already been used as display devices in various devices.

Among them, the liquid crystal display is the most widely used, replacing the CRT (Cathode Ray Tube) for mobile image display due to the excellent image quality, light weight, thinness, and low power consumption. In addition to the mobile use, various developments have been made for televisions and monitors for receiving and displaying broadcast signals.

The liquid crystal display includes a color filter substrate having a color filter array, a thin film transistor substrate having a thin film transistor array, and a liquid crystal layer formed between the color filter substrate and the thin film transistor substrate.

The color filter substrate is formed with a color filter for color implementation and a black matrix for light leakage prevention. In the thin film transistor substrate, a plurality of pixel electrodes to which data signals are separately supplied are formed in a matrix form. Also, a thin film transistor for driving a plurality of pixel electrodes individually, a gate line for controlling the thin film transistor, and a data line for supplying a data signal to the thin film transistor are formed on the thin film transistor substrate.

The liquid crystal molecules are thin and long in structure and have an orientation in the arrangement. When an electric field is applied to the liquid crystal display, the liquid crystal molecules are moved by an electric field applied to the liquid crystal layer, and the light transmittance is changed to display an image or a character. Such liquid crystal display devices have been spotlighted as next generation advanced display devices due to their excellent image quality, light weight, and low power consumption.

Hereinafter, a general liquid crystal display will be described with reference to the accompanying drawings.

FIG. 1 is a cross-sectional view of a general liquid crystal display and illustrates only a thin film transistor substrate.

As shown in FIG. 1, a thin film transistor substrate of a general liquid crystal display device includes a gate insulating film formed on the entire surface of the substrate 100 including the substrate 100, the gate electrode 110a formed on the substrate 100, and the gate electrode 110a. 120, the active layer 130 formed on the gate insulating layer 120 and the semiconductor layer 130a and the ohmic contact layer 130b are sequentially stacked, the source formed on the active layer 130 and spaced apart from a predetermined region, A protective layer 150 formed on the entire surface of the gate insulating layer 120 including the drain electrodes 140a and 140b, the source and the drain electrodes 140a and 140b, and a contact hole formed by selectively removing the protective layer 150. The pixel electrode 160 is connected to the drain electrode 140b.

However, when the passivation layer 150 is formed of the organic insulating layer on the entire gate insulating layer 120 including the source and drain electrodes 140a and 140b formed of the metal material, the source and drain electrodes 140a may be formed due to the material difference between the metal and the organic insulating layer. , 140b) and the protective film 150 are degraded.

Specifically, when a hole is formed between the source and drain electrodes 140a and 140b and the passivation layer 150 due to the passivation layer 150 having poor contact characteristics, foreign matter may be mixed in the passivation layer 150. . As a result, a defect of the liquid crystal display may occur, and the etchant may be caused when the passivation layer 150 does not function properly to form a contact hole in the passivation layer 150 or to form the pixel electrode 160 on the passivation layer 150. (Etchant) causes a problem that the thin film transistor and the electrode of the liquid crystal display is damaged.

The present invention has been made to solve the above problems, the first protective film is laminated with an inorganic insulating film and an organic insulating film to ensure fairness, the organic insulating film can reduce the power consumption by reducing the load between the source and the common electrode It is an object of the present invention to provide a liquid crystal display device and a method for manufacturing the same.

The liquid crystal display device of the present invention for achieving the above object, the substrate; A gate line and a data line formed vertically and horizontally on the substrate to define a pixel area; A thin film transistor formed at an intersection of the gate line and the data line; A first passivation layer formed on the substrate including the thin film transistor and in which an inorganic insulating layer and an organic insulating layer are sequentially stacked; A pixel electrode formed on the first passivation layer; A second passivation layer formed on an entire surface of the first passivation layer including the pixel electrode; A second contact hole exposing the pixel electrode by selectively removing the first and second passivation layers by selectively removing the first and second passivation layers to expose the drain electrode of the thin film transistor; A connection electrode formed on the second passivation layer and connecting the drain electrode and the pixel electrode through the first and second contact holes; And a common electrode formed on the same layer as the connection electrode to form a fringe electric field with the pixel electrode.

The thickness of the inorganic insulating film of the first protective film is thinner than the thickness of the organic insulating film.

The inorganic insulating film has a thickness of 1000 kPa to 2000 kPa.

The common electrode has a plurality of open regions.

The connection electrode is formed in an island shape on the second passivation layer.

The upper surface of the second passivation layer is flat.

In addition, the manufacturing method of the liquid crystal display device of the present invention for achieving the same object comprises the steps of forming a gate line and a gate electrode on a substrate; Forming a gate insulating film on the substrate including the gate line and a gate electrode; Forming an active layer in which a semiconductor layer and an ohmic contact layer are sequentially stacked on the gate insulating layer; Depositing and patterning a data electrode material on the gate insulating layer including the active layer to form a source line and a drain electrode at the same time as forming a data line crossing the gate line to define a pixel region; Forming a first passivation layer by sequentially depositing an inorganic insulating layer and an organic insulating layer on the gate insulating layer including a source and a drain electrode; Forming a pixel electrode on the first passivation layer; Forming a second passivation layer on an entire surface of the first passivation layer including the pixel electrode; Selectively removing the first and second passivation layers to form a first contact hole exposing the drain electrode and selectively removing only the second passivation layer to form a second contact hole exposing the pixel electrode; And forming a connection electrode connecting the drain electrode and the pixel electrode through the first and second contact holes and forming a common electrode forming a fringe electric field with the pixel electrode.

The first contact hole and the second contact hole are simultaneously formed.

The organic insulating film of the first protective film is formed thicker than the inorganic insulating film.

The common electrode is formed to have a plurality of open regions.

The connection electrode is formed in an island shape on the second passivation layer.

As described above, the liquid crystal display of the present invention and a method of manufacturing the same may form a protective film in which an inorganic insulating film and an organic insulating film are sequentially stacked on a gate insulating film including a source and a drain electrode, thereby improving contact characteristics between the source and drain electrodes and the protective film. Can be. In addition, the capacitance formed between the common electrode and the data line may be reduced to improve the image quality of the liquid crystal display and to reduce power consumption.

1 is a cross-sectional view of a general liquid crystal display device.
2 is a plan view of the liquid crystal display of the present invention.
3A is a cross-sectional view taken along the line II ′ of FIG. 2.
3b is a sectional view taken along the line II-II 'of FIG. 2;
4A to 4F are cross-sectional views illustrating a method of manufacturing the liquid crystal display of the present invention.

The most common driving mode used in the liquid crystal display is a twisted nematic (TN) mode in which the liquid crystal directors are arranged so that the liquid crystal directors are twisted by 90 ° and then applied a voltage to the liquid crystal directors, and pixels arranged side by side on a substrate. There is an In-Plane Switching Mode mode in which a liquid crystal is driven by a horizontal electric field between the electrode and the common electrode.

In the transverse electric field mode, the pixel electrode and the common electrode are alternately formed in the opening of the thin film transistor substrate so that the liquid crystal is aligned by the transverse electric field generated between the pixel electrode and the common electrode. However, since the transverse electric field mode liquid crystal display has a wide viewing angle but a low aperture ratio and a low transmittance, a fringe field switching (FFS) mode liquid crystal display has been proposed to solve the above problems.

In the fringe field mode liquid crystal display, a pixel electrode in the form of a through electrode is formed in a pixel region, and a plurality of common electrodes are formed in a slit form on the pixel electrode to operate liquid crystal molecules by a fringe electric field formed between the pixel electrode and the common electrode. Let's do it.

Since the fringe field mode liquid crystal display device can precisely control the liquid crystal molecules, the upper, lower, left, and right 180 ° wide viewing angles can be realized, and color contrast can be obtained even in a diagonal direction and a high contrast ratio can be obtained. In addition, the structure covering the common electrode on the data line may reduce the line width of the black matrix to improve the aperture ratio.

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

2 is a plan view of the liquid crystal display of the present invention. 3A and 3B are cross-sectional views taken along the line II ′ of FIG. 2 and II-II ′ of FIG. 2, respectively.

2, 3A, and 3B, the liquid crystal display of the present invention is formed on the substrate 200 and the substrate 200 vertically and horizontally to define a pixel area, a gate line GL and a data line DL. , A first passivation layer formed on the substrate 200 including the thin film transistor and the thin film transistor formed at the intersection of the gate line GL and the data line DL, and the inorganic insulating film 250a and the organic insulating film 250b are sequentially stacked. The second passivation layer 270 and the first and second passivation layers formed on the entire surface of the first passivation layer 250 including the pixel electrode 260 and the pixel electrode 260 formed on the first passivation layer 250. A second exposing the pixel electrode 260 by selectively removing only the first contact hole 290a and the second passivation layer 270 by selectively removing the 250 and 270 to expose the drain electrode 240b of the thin film transistor. It is formed on the contact hole 290b and the second passivation layer 270 and through the first and second contact holes 290a and 290b. It includes an electrode (240b) and the pixel electrode 260 connected to the electrode (280b) and the connection electrode (280b) and the common electrode (280a) is formed in the same layer forming the pixel electrode 260 and the fringe field for connecting.

In detail, the thin film transistor includes a gate electrode 210a connected to the gate line GL, a gate insulating film 220 formed on the entire surface of the substrate 200 including the gate line GL and the gate electrode 210a, and a gate. An active layer 230 including a semiconductor layer 230a and an ohmic contact layer 230b formed on the gate insulating layer 220 corresponding to the electrode 210a, a source electrode 240a connected to the data line DL, and The drain electrode 240b is formed to be spaced apart from the source electrode 240a by a predetermined interval.

In the spaced interval between the source electrode 240a and the drain electrode 240b, the ohmic contact layer 230b is removed to form a channel ch.

However, in a general liquid crystal display device, since a protective film is formed of an organic insulating film on the entire gate insulating film including a thin film transistor, the contact characteristics of the source, drain electrode, and protective film are degraded due to the difference between the source, drain electrode, and organic insulating film formed of a metal material. do.

In other words, the protective film is excited without uniformly contacting the entire surface of the gate insulating film including the thin film transistor. Therefore, a hole may be formed between the source, drain electrode, and the passivation layer, and foreign matter may be mixed in the hole. In addition, in the general liquid crystal display, when the contact hole is formed in the passivation layer or the pixel electrode is formed on the passivation layer, the passivation layer may not function properly due to an etchant, which may cause a defect of the thin film transistor.

In order to prevent the defects described above, when the protective film is formed of only an inorganic insulating film, the larger the area of the liquid crystal display device, the more the data line and the common electrode are overloaded, thereby degrading the image quality of the liquid crystal display device. Power is increased.

Accordingly, the present invention forms the first passivation layer 250 in which the inorganic insulating layer 250a and the organic insulating layer 250b are sequentially stacked on the gate insulating layer 220 including the thin film transistor. The inorganic insulating layer 250a of the first passivation layer 250 may improve contact characteristics between the source and drain electrodes 240a and 240b formed of a metal material and the first passivation layer 250.

In this case, the inorganic insulating film 250a is preferably silicon nitride (SiNx) and the organic insulating film 250b is photo acryl. The top surface of the organic insulating film 250b is flat to contact the pixel electrode 260. Characteristics are improved. In addition, the inorganic insulating film 250a is thinner than the organic insulating film 250b because the inorganic insulating film 250a is for improving the contact characteristics between the first passivation film 250 and the thin film transistor, and specifically, the thickness of the inorganic insulating film 250a is 1000 kPa to 2000 kPa. The thickness of the organic insulating film 250b is preferably 1.5 µm to 4 µm.

In the liquid crystal display of the present invention as described above, a hole may be formed between the first passivation layer 250 and the thin film transistor to prevent a failure of the liquid crystal display. In addition, the structure in which the inorganic insulating layer 250a and the organic insulating layer 250b are sequentially stacked may reduce capacitance that is formed between the common electrode 280a and the data line DL, thereby reducing power consumption.

On the other hand, the capacitance is determined by the following equation (1).

Where C is the capacitance, d is the thickness of the protective film, S is the conductive surface area, ε r is the dielectric constant, and ε o is the dielectric constant of the free space, 8.854 x 10 ^-12 .

A general liquid crystal display device forms a passivation layer only with an inorganic insulating layer such as silicon nitride (SiNx), but the present invention stacks an inorganic insulating layer such as silicon nitride (SiNx) and an organic insulating layer such as photo acryl in order to form a passivation layer. Form. At this time, it is preferable that the thickness of the inorganic insulating film of this invention is 1000 kPa-2000 kPa, and the thickness of the organic insulating film 250b is 1.5 micrometer-4 micrometers.

However, since the dielectric constant of the inorganic insulating film is about 2 times higher than the dielectric constant of the organic insulating film, the capacitance between the common electrode and the data line of the present invention is calculated by substituting in Equation 1, compared to the capacitance of the general liquid crystal display device. Decreases to about 1/10.

Therefore, the liquid crystal display of the present invention not only reduces the load of the common electrode, reduces power consumption, but also improves the image quality of the liquid crystal display. In the liquid crystal display of the present invention, since the thickness of the inorganic insulating film is remarkably thin compared to the thickness of the organic insulating film, the organic insulating film may be substituted by only the organic insulating film in Equation (1).

2, 3A, and 3B, the second passivation layer 270 formed on the entire surface of the first passivation layer 250 including the pixel electrode 260 may be formed of an inorganic insulating layer, and may be silicon nitride (SiNx). Do. The common electrode 280a having a plurality of open regions is formed on the second passivation layer 270, and the plurality of open regions may have a rod shape.

The first and second contact holes 290a and 290b are used to connect the pixel electrode 260 and the drain electrode 240b. The first contact hole 290a connects the first and second passivation layers 250 and 270. The second contact hole 290b is formed by selectively removing only the second passivation layer 270.

The first and second contact holes 290a expose portions of the drain electrode 240b and portions of the pixel electrode 260, respectively. The connection electrode 280b formed on the same layer as the common electrode 280a is formed in an island shape to connect the pixel electrode 260 and the drain electrode 240b through the first and second contact holes 290a and 290b. Let's do it.

That is, the video signal of the drain electrode 240b is supplied to the pixel electrode 260 through the connection electrode 280b, and a fringe electric field is formed between the common electrode 280a and the pixel electrode 260 supplied with the common voltage. Liquid crystal molecules work.

The pixel electrode 260, the common electrode 280a, and the connection electrode 280b may be formed of a transparent electrode or may be formed of a light blocking metal. In the former case, indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (TO), or indium tin zinc oxide (ITZO) is selected from The latter case is selected from a light shielding material such as molybdenum or molybdenum laminate, copper, aluminum, aluminum-neodium alloy, chromium.

In the liquid crystal display of the present invention as described above, the contact characteristics of the source and drain electrodes 240a and 240b and the first passivation layer 250 may be improved to prevent defects of the liquid crystal display, and the common electrode 280a and the data may be prevented. The capacitance between the lines DL is reduced, so that the image quality of the liquid crystal display is improved and power consumption is reduced.

Hereinafter, the manufacturing method of the liquid crystal display device of the present invention will be described in detail.

4A to 4F are cross-sectional views illustrating a method of manufacturing the liquid crystal display of the present invention.

As shown in FIG. 4A, a gate electrode material (not shown) is deposited on the entire surface of the substrate 200 through a deposition method such as a sputtering method, and then a gate line (not shown) and a photolithography process using a first mask. The gate electrode 210a is formed. The gate insulating layer 220 is formed on the entire surface of the substrate 200 including the gate line and the gate electrode 210a.

As shown in FIG. 4B, the active layer 230 in which the semiconductor layer 230a and the ohmic contact layer 230b are sequentially stacked is formed on the gate insulating layer 220 corresponding to the gate electrode 210a by using a second mask. do.

As illustrated in FIG. 4C, a data electrode material (not shown) is deposited on the entire surface of the gate insulating layer 220 including the active layer 230. The data electrode material is patterned using a third mask to form a data line (not shown) that vertically crosses the gate line (not shown) to define a pixel area, and protrudes from the data line (not shown). Source and drain electrodes 240a and 240b are formed.

Meanwhile, as shown in FIG. 4B, when the active layer 230 is formed, the ohmic contact layer 230b is removed to form a channel, or when the source and drain electrodes 240a and 240b are formed, the ohmic contact layer 230b. ) May be removed to form a channel.

Subsequently, as shown in FIG. 4D, the inorganic insulating film 250a and the organic insulating film are formed on the entire gate insulating film 220 including the thin film transistor including the gate electrode 210a, the active layer 230, and the source and drain electrodes 240a and 240b. The first passivation layer 250 is formed by sequentially stacking the 250 b layers. At this time, the thickness of the inorganic insulating film 250a is formed to be thinner than the thickness of the organic insulating film 250b.

As described above, the first passivation layer 250, in which the inorganic insulating layer 250a and the organic insulating layer 250b are sequentially stacked, has improved contact characteristics with the source and drain electrodes 240a and 240b, and thus the first passivation layer 250 and the thin film transistor. It prevents the formation of a hole (Hole) between. Therefore, it is possible to prevent the failure of the liquid crystal display device from occurring.

As shown in FIG. 4E, the pixel electrode 260 is formed on the first passivation layer 250 using the fourth mask, and the second passivation layer 270 is formed on the entire surface of the first passivation layer 250 including the pixel electrode 260. Form. In order to connect the pixel electrode 260 and the drain electrode 240b, the first and second passivation layers 250 and 270 are selectively removed using a fifth mask to form a first contact hole 290a. Only the second passivation layer 270 is selectively removed to form the second contact hole 290b. In order to form the first and second contact holes 290a and 290b, it is preferable to use a dry etching method.

The first and second contact holes 290a and 290b are formed at the same time, and the first and second contact holes 290a expose part of the drain electrode 240b and part of the pixel electrode 260, respectively. In this case, the inorganic insulating layer 250a of the first passivation layer 250 may be damaged by an etchant when forming a contact hole in the first passivation layer or forming a pixel electrode on the first passivation layer. prevent.

4F, a common electrode 280a having a plurality of open regions is formed on the second passivation layer 270 using a sixth mask, and formed in an island shape on the same layer as the common electrode 280a. To form a connection electrode 280b connecting the pixel electrode 260 and the drain electrode 240b through the first and second contact holes 290a and 290b.

That is, the video signal of the drain electrode 240b is supplied to the pixel electrode 260 through the connection electrode 280b, and a fringe electric field is formed between the common electrode 280a and the pixel electrode 260 supplied with the common voltage. Liquid crystal molecules work.

As described above, in the method of manufacturing the liquid crystal display of the present invention, capacitance formed between the common electrode 280a and a data line (not shown) is reduced, thereby improving image quality of the liquid crystal display and reducing power consumption.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Will be apparent to those of ordinary skill in the art.

200: substrate 210a: gate electrode
220: gate insulating film 230: active layer
230a: semiconductor layer 230b: ohmic contact layer
240a: source electrode 240b: drain electrode
250: first protective film 250a: inorganic insulating film
250b: organic insulating film 260: pixel electrode
270: second protective film 280a: common electrode
280b: connection electrode 290a: first contact hole
290b: second contact hole

Claims (11)

Board;
A gate line and a data line formed vertically and horizontally on the substrate to define a pixel area;
A thin film transistor formed at an intersection of the gate line and the data line;
A first passivation layer formed on the substrate including the thin film transistor and in which an inorganic insulating layer and an organic insulating layer are sequentially stacked;
A pixel electrode formed on the first passivation layer;
A second passivation layer formed on an entire surface of the first passivation layer including the pixel electrode;
A second contact hole exposing the pixel electrode by selectively removing the first and second passivation layers by selectively removing the first and second passivation layers to expose the drain electrode of the thin film transistor;
A connection electrode formed on the second passivation layer and connecting the drain electrode and the pixel electrode through the first and second contact holes; And
And a common electrode formed on the same layer as the connection electrode to form a fringe electric field with the pixel electrode. The method of claim 1,
The thickness of the inorganic insulating film of the first protective film is thinner than the thickness of the organic insulating film. The method of claim 2,
The inorganic insulating film has a thickness of 1000 kPa to 2000 kPa. The method of claim 1,
And the common electrode has a plurality of open regions. The method of claim 1,
And the connection electrode is formed in an island shape on the second passivation layer. The method of claim 1,
And a top surface of the second passivation layer is flat. Forming a gate line and a gate electrode on the substrate;
Forming a gate insulating film on the substrate including the gate line and a gate electrode;
Forming an active layer in which a semiconductor layer and an ohmic contact layer are sequentially stacked on the gate insulating layer;
Depositing and patterning a data electrode material on the gate insulating layer including the active layer to form a source line and a drain electrode at the same time as forming a data line crossing the gate line to define a pixel region;
Forming a first passivation layer by sequentially depositing an inorganic insulating layer and an organic insulating layer on the gate insulating layer including a source and a drain electrode;
Forming a pixel electrode on the first passivation layer;
Forming a second passivation layer on an entire surface of the first passivation layer including the pixel electrode;
Selectively removing the first and second passivation layers to form a first contact hole exposing the drain electrode and selectively removing only the second passivation layer to form a second contact hole exposing the pixel electrode; And
And forming a connection electrode connecting the drain electrode and the pixel electrode through the first and second contact holes and forming a common electrode forming a fringe electric field with the pixel electrode. The method of claim 7, wherein
And forming the first contact hole and the second contact hole at the same time. The method of claim 7, wherein
The organic insulating film of the first protective film is formed thicker than the inorganic insulating film. The method of claim 7, wherein
The common electrode may be formed to have a plurality of open regions. The method of claim 7, wherein
The connection electrode may be formed in an island shape on the second passivation layer.

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