KR20040046791A - Liquid crystal display device - Google Patents

Abstract

PURPOSE: An LCD(Liquid Crystal Display) is provided to minimize the change of the vertical capacitance between a data line and a pixel electrode, although a pattern shift phenomenon is generated, thereby preventing a longitudinal spot of a chuck. CONSTITUTION: A gate line(42) is extended on a lower substrate with a direction. A data line(45) defines a pixel region by crossing the gate line(42) and is extended with a direction. A source electrode(45a) is protruded from a side of the data line(45) and a drain electrode(45b) is separated from the source electrode(45a) with a predetermined distance. At the crossed portion of the gate line(42) and the data line(45), a thin film transistor having a gate electrode, a source electrode, a drain electrode, a gate insulation film, and an active layer is formed. At the pixel region, a transparent pixel electrode(47) is formed and at this time the pixel electrode(47) is contacted to the drain electrode(45b) and a storage upper electrode through a contact hole.

Description

Liquid crystal display device {LIQUID CRYSTAL DISPLAY DEVICE}

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 suitable for preventing the occurrence of a vertical line defect of a chuck due to a pattern distortion caused by a chuck shape and a change in vertical capacitance during a photo process.

As the information society develops, the demand for display devices is gradually increasing in various forms, and in recent years, liquid crystal display devices (LCDs), plasma display panels (PDPs), electro luminescent displays (ELDs), and VFDs (Vacuum) Various flat panel display devices such as fluorescent display have been studied, and some are already used as display devices in various devices.

Among them, LCD is the most used as a substitute for CRT (Cathode Ray Tube) for mobile image display device because of the excellent image quality, light weight, thinness, and low power consumption. In addition to mobile type such as notebook computer monitor, BACKGROUND ART Various developments have been made in televisions and computer monitors for receiving and displaying broadcast signals.

Although various technical advances have been made in order for such a liquid crystal display device to serve as a screen display device in various fields, the task of improving the image quality as the screen display device is often arranged with the above characteristics and advantages.

Therefore, in order to use a liquid crystal display as a general screen display device in various parts, it is a matter of how high quality images such as high definition, high brightness and large area can be realized while maintaining the characteristics of light weight, thinness and low power consumption. have.

Such a liquid crystal display may be classified into a liquid crystal panel displaying an image and a driving unit for applying a driving signal to the liquid crystal panel.

The liquid crystal panel includes a lower substrate in which a plurality of pixel regions are arranged in a matrix form, one thin film transistor and one pixel electrode arranged for each pixel, an upper substrate including a color filter and a common electrode for displaying color; The liquid crystal layer is filled between the upper substrate and the lower substrate.

Polarizing plates for linearly polarizing visible light (natural light) are attached to both surfaces of the upper and lower substrates, respectively.

Here, the lower substrate (TFT array substrate) includes a plurality of gate wirings arranged in one direction at a predetermined interval, a plurality of data wirings arranged at regular intervals in a direction perpendicular to the respective gate wirings, and the respective gate wirings. A plurality of pixel electrodes formed in a matrix form in each pixel region defined by intersections of the data lines and a plurality of thin film transistors which are switched by signals of the gate lines to transfer the signals of the data lines to the pixel electrodes. Is formed.

In the upper substrate (color filter substrate), a black matrix layer for blocking light except for the pixel region, an R, G, and B color filter layer for expressing color colors, and a common electrode for implementing an image are formed. do.

In addition, the upper substrate and the lower substrate thus formed have a predetermined space by a spacer for maintaining a cell gap, and are bonded by a sealant. And liquid crystal is formed in the space inside a seal material.

When manufacturing a liquid crystal display device having such a structure, instead of forming one liquid crystal panel on one glass substrate, a plurality of liquid crystal panels are simultaneously formed on one large substrate according to the size of the glass substrate and the size of the liquid crystal panel. do.

The liquid crystal display device configured as described above includes a manufacturing process of a panel upper substrate and a lower substrate accompanied with a process of forming a liquid crystal cell forming a pixel unit, forming and rubbing an alignment layer for liquid crystal alignment, and an upper substrate and a lower substrate. The substrate is bonded through a plurality of processes, such as a process of injecting and encapsulating a liquid crystal between the bonded upper and lower substrates.

Here, the manufacturing process of the lower substrate includes forming a thin film transistor (TFT) portion and forming other electrode portions by applying and etching an electrode material, a semiconductor layer, and an insulating layer on the substrate. do.

After the liquid crystal injection and encapsulation process, polarizing plates are attached to both sides of the upper and lower substrates to complete the liquid crystal panel.

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

1 is a plan view showing a vacuum chuck for manufacturing a general liquid crystal display device and a glass substrate mounted thereon.

2 is an enlarged plan view of a unit pixel of a liquid crystal display device according to the prior art, and FIGS. 3A and 3B are cross-sectional views taken along line II ′ of FIG. 2 according to the prior art.

The vacuum chuck for manufacturing the liquid crystal display device according to the prior art is made of a metal material as shown in Figure 1 and the support portion 11 and a plurality of protrusions configured to mount the glass substrate 10, the glass substrate 10 ) Is composed of a vacuum line (12) formed between the protruding support (11) to be seated on the support (11) of the vacuum chuck.

At this time, the support portion 11 is a rectangular edge-shaped protrusions are formed repeatedly from the edge of the chuck to the center with a predetermined interval, the glass substrate 10 is seated on the protruding support portion 11 of the vacuum chuck.

At this time, the glass substrate 10 shows a lower substrate, and a gate pad is formed at one edge thereof, and a source pad is formed at the other edge thereof perpendicular thereto.

Hereinafter, the configuration of the liquid crystal display device according to the related art manufactured using the vacuum chuck will be described.

2. Description of the Related Art A conventional liquid crystal display device has a gate line 32 extending in one direction on the lower substrate 31 as illustrated in FIGS. 2 and 3A, and defines a pixel area crossing the gate line 32 to define a pixel area. There is an extended data line 35.

A source electrode 35a is formed to protrude from the data line 35, and a drain electrode 35b is formed to be spaced apart from the source electrode 35a by a predetermined interval.

In this case, the source electrode 35a protrudes to have a '⊂' shaped groove, and the drain electrode 35b is spaced apart from the source electrode 35a at a predetermined interval inside the '⊂' shaped groove. An active channel is formed in a '⊂' shape between the electrode 35a and the drain electrode 35b.

The gate electrode 32a protrudes to one side of the gate line 32, and a gate insulating layer 33 is formed on the lower substrate 31 including the gate line 32.

An active layer 34 is formed on the gate electrode 32a and on the gate insulating layer 33 below the data line 35, the source electrode 35a, and the drain electrode 35b.

In this case, the active layer 34 is formed to have a narrower width than the data line 35, the source electrode 35a, and the drain electrode 35b, and is formed by stacking an amorphous silicon layer 34a and an n + amorphous silicon layer 34b. .

In addition, the front gate line of the storage capacitor formation region serves as a storage lower electrode, and the upper storage electrode is formed in an island shape on the upper gate insulating layer.

In this case, the storage upper electrode is formed in an island shape when the active layer and the data line are formed.

The passivation layer 36 is formed on the entire lower substrate 31 including the data line 35, and the passivation layer 36 has contact holes on one region of the drain electrode 35b and the storage upper electrode.

In addition, a transparent pixel electrode 37 is formed in the pixel region, wherein the pixel electrode 37 is in contact with the drain electrode 35b and the upper storage electrode through the contact hole.

When the liquid crystal display device having the above configuration is manufactured by using the vacuum chuck of FIG. 1, since the support part 11 of the vacuum chuck is formed with curvature, the glass substrate (especially the lower substrate) seated thereon This curvature causes the light to be distorted during the photo process due to the curvature, thereby preventing a desired pattern from being formed.

In particular, when the data line 35 and the active layer 34 are patterned, the protective film 36 overlaps the pixel electrode 37 by a pattern shift phenomenon for each process step, as shown in FIG. 3B. The thickness is varied, resulting in a difference in overlapping vertical capacitance.

In other words, in FIG. 3A, when the thickness of the active layer 34 overlaps the pixel electrode 37 is t1 and the thickness of the overlap between the data line 35 and the pixel electrode 37 is t2, a photo process using a vacuum chuck is used. When the data line 35 and the active layer 34 are patterned, if a pattern shift phenomenon occurs, as illustrated in FIG. 3B, the thickness at which the active layer 34 and the pixel electrode 37 overlap is t1 to t1 ′. In addition, the overlapping area of the data line 35 and the pixel electrode 37 may be reduced or increased.

When the pattern shift phenomenon occurs during the photo process using the vacuum chuck as described above, the area where the data line overlaps the pixel electrode and the overlapping vertical thickness are changed to increase the Cdp deviation. Problems intensify.

The present invention has been made to solve the above problems, and an object of the present invention is to minimize the vertical capacitance change between the data line and the pixel electrode even if a pattern shift occurs, so that the liquid crystal display is suitable for preventing the occurrence of vertical line irregularities in the chuck. It is to provide an element.

1 is a plan view showing a vacuum chuck and a glass substrate mounted on an upper portion of a general liquid crystal display device

2 is an enlarged plan view of a unit pixel of a liquid crystal display according to the related art.

3A and 3B are cross-sectional views taken along line II ′ of FIG. 2 according to the prior art.

4 is an enlarged plan view of a unit pixel of a liquid crystal display according to an exemplary embodiment of the present invention.

5 is a structural cross-sectional view taken along line II-II 'of FIG. 4 according to the present invention.

6 is a cross-sectional view taken along line III-III 'of FIG. 4 according to the present invention.

Explanation of symbols on the main parts of the drawings

41: lower substrate 42: gate line

42a: gate electrode 43: gate insulating film

44: active layer 45: data line

46: protective film 47: pixel electrode

According to an aspect of the present invention, there is provided a liquid crystal display device including: a plurality of gate lines and data lines intersecting to define a pixel area; A thin film transistor formed at an intersection of the gate line and the data line; An active layer formed on an upper side of the gate line to protrude to the left and right sides of the data line around the data line to have a zigzag shape; And a pixel electrode formed in the pixel region.

The present invention relates to a configuration for improving the vertical line unevenness of the chuck by preventing the Cdp deviation and the luminance difference does not occur even if the pattern distortion occurs during the photo process due to the shape of the vacuum chuck.

Hereinafter, a liquid crystal display device according to an exemplary embodiment of the present invention will be described with reference to the accompanying drawings.

4 is an enlarged plan view of a unit pixel of a liquid crystal display according to an exemplary embodiment of the present invention.

5 is a cross-sectional view taken along line II-II 'of FIG. 4 according to the present invention, and FIG. 6 is a cross-sectional view taken along line III-III' of FIG. 4 according to the present invention.

As shown in FIG. 4, the liquid crystal display according to the exemplary embodiment of the present invention has a gate line 42 extending in one direction on the lower substrate 41, and defines a pixel area by crossing the gate line 42. And a data line 45 extending in one direction.

There is a source electrode 45a protruding from one side of the data line 45, and a drain electrode 45b spaced apart from the source electrode 45a by a predetermined interval.

In this case, the source electrode 45a protrudes to have a '⊂' shaped groove, and the drain electrode 45b is spaced apart from the source electrode 45a at a predetermined interval inside the '⊂' shaped groove. An active channel is formed in a '⊂' shape between the electrode 45a and the drain electrode 45b.

The gate electrode 42a protrudes toward one side of the gate line 42, and a gate insulating layer 43 is formed on the lower substrate 41 including the gate line 42.

An active layer 44 is formed on the gate electrode 42a and on the gate insulating layer 43 below the data line 45, the source electrode 45a, and the drain electrode 45b.

In this case, the active layer 44 is formed to have a narrower width than the data line 45, the source electrode 45a, and the drain electrode 45b, and is formed by stacking the amorphous silicon layer 44a and the n + amorphous silicon layer 44b. .

In addition, the active layer 44 formed in the data line 45 direction is formed to have a zigzag shape with respect to the data line 45.

In more detail, the active layer 44 protrudes alternately to the left and right sides of the data line 45 around the data line 45, and the width and length of the active layer 44 protruding to the left and right sides are the same.

For example, if the width of the active layer 44 is approximately 4 μm, the width protruding into the data line 45 is about 1 μm from the left and right sides, and the interval between the protruding active layer 44 and the pixel area is increased. The interval before the active layer 44 protrudes can be configured to be about 10 μm.

As described above, the gate electrode 42a and the source electrode 45a, the drain electrode 45b, the gate insulating layer 43, and the active layer 44 are provided at the intersection of the gate line 42 and the data line 45. Thin film transistor is formed.

The front gate line of the storage capacitor formation region serves as a storage lower electrode, and the upper storage electrode is formed in an island shape on the gate insulating layer 43 on the upper side thereof.

In this case, the storage upper electrode is formed in an island shape when the active layer and the data line are formed.

The passivation layer 46 is formed on the entire surface of the lower substrate 41 including the data line 45. The passivation layer 46 has contact holes on one region of the drain electrode 45b and the storage upper electrode. This is flattened.

In this case, the protective layer 46 may be formed of an inorganic insulating material such as silicon nitride (Si 3 N 4) or silicon oxide (SiO 2), or an acrylic organic compound, Teflon, BCB (benzocyclobuten), Cytop, or PFCB ( It is formed of at least one of organic substances such as perfluorocyclobutane.

In addition, the transparent pixel electrode 47 is formed in the pixel area, and the pixel electrode 47 is in contact with the drain electrode 45b and the storage upper electrode through the contact hole.

As shown in FIGS. 4, 5, and 6, when the active layer 44 is zigzag-shaped so as to protrude alternately left and right around the data line 45, the active layer 44 is left or right. Even if it is shifted, the average change in the vertical capacitance due to the change in the area where the data line 45 and the pixel electrode 47 overlap and the thickness change ('t3' and 't4') of the passivation layer 46 can be minimized. .

For example, even when shifted to the left side, the change in the vertical capacitance caused by the left shift to some extent can be compensated by the active layer protruding to the right side.

The present invention is not limited to the above embodiments, and includes various forms that can be easily derived by those skilled in the art from the above embodiments.

The liquid crystal display of the present invention as described above has the following effects.

If the active layer is formed zigzag to protrude to the left and right around the data line, even if the pattern shift phenomenon occurs, the change in the vertical capacitance due to the change in the area where the data line and the pixel electrode overlap and the thickness of the protective film are minimized. Can be.

As a result, it is possible to prevent the chuck vertical line staining problem from occurring.

Claims (5)

A plurality of gate lines and data lines intersecting to define a pixel area; A thin film transistor formed at an intersection of the gate line and the data line; An active layer formed on an upper side of the gate line to protrude to the left and right sides of the data line around the data line to have a zigzag shape; And a pixel electrode formed in the pixel region. The method of claim 1, The thin film transistor may include a gate electrode protruding from one side of the gate line; A gate insulating film formed on the entire surface of the substrate; A source electrode protruding from the data line; A drain electrode spaced apart from the source electrode and overlapping with one region of the active layer; And an active layer formed on the gate electrode and on the gate insulating layer below the data line, the source electrode, and the drain electrode. The method of claim 2, The source electrode has a '⊂' shaped groove, the liquid crystal display device. The method of claim 2 or 3, And the drain electrode is formed to be spaced apart from the source electrode by a predetermined interval inside the groove of the '⊂' shape. The method of claim 1, And a length and a width of the active layer protruding to the left and right sides of the data line are the same.