KR20170045618A - Liquid crystal display device having uniform alignment layer - Google Patents

Abstract

According to the present invention, an alignment liquid is introduced into a contact hole by removing a step generated by a pixel electrode disposed around the contact hole. At this time, an entire one side of the pixel electrode around the contact hole is removed to form an introduction path through which the alignment liquid is introduced. Also, a specific region of a predetermined width and length is removed to form the introduction path so that the alignment liquid is smoothly introduced into the contact hole through the introduction path, and at the same time, a penetration path of an etchant used to etch the pixel electrode is extended to the maximum to prevent the etchant from penetrating into the pixel electrode.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device having a uniform alignment layer,

The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device capable of preventing the occurrence of light leakage on the screen due to unevenly formed alignment films due to stepped portions and contact holes of the pixel electrodes when an alignment film is formed by an ink- Device.

2. Description of the Related Art In recent years, the size of a flat panel display device used for various portable electronic devices such as a mobile phone, a PDA, and a notebook computer and a television has been gradually increasing. As such a flat panel display device, a liquid crystal display (LCD), a plasma display panel (PDP), and an organic light emitting device panel (OLED) have been actively studied and especially because of mass production technology, ease of driving means, Liquid crystal display devices (LCDs) have been widely applied.

1 schematically shows a cross section of a general liquid crystal display element. The liquid crystal display element 1 includes a first substrate 3 and a second substrate 5 and a liquid crystal layer 7 formed between the first substrate 3 and the second substrate 5, . The first substrate 3 is a driving element array substrate. Although not shown in the drawing, a plurality of pixels are formed on the first substrate 5, and a thin film transistor (TFT) The same driving element is formed. The second substrate 5 is a color filter substrate, and a color filter layer for realizing colors is formed. In addition, pixel electrodes and common electrodes are formed on the first substrate 3 and the second substrate 5, respectively, and an alignment film for aligning the liquid crystal molecules of the liquid crystal layer 7 is coated.

The first substrate 3 and the second substrate 5 are bonded together by a sealing material 9 and a liquid crystal layer 7 is formed therebetween to form a drive Information is displayed by controlling the amount of light transmitted through the liquid crystal layer by driving the liquid crystal molecules by the device.

The manufacturing process of the liquid crystal display device is largely divided into a driving device array substrate process for forming a driving device on the first substrate 3, a color filter substrate process for forming a color filter on the second substrate 5, and a cell process The manufacturing process of such a liquid crystal display device will be briefly described as follows.

First, a plurality of gate lines (Gate Line) and a data line (Date Line), which are arranged on the first substrate 3 by a driving element array process and define a pixel region, are formed, And a thin film transistor which is a driving element connected to the data line is formed. In addition, a pixel electrode and a common electrode for driving the liquid crystal layer are formed as the signal is applied to the thin film transistor through the thin film transistor through the driving element array process.

The third substrate 5 is also provided with a color filter layer of R, G, and B that emits color by a color filter process and a black matrix that blocks light from being transmitted through the image non-display area.

Subsequently, the liquid crystal molecules of the liquid crystal layer formed between the first substrate 3 and the second substrate 5 after applying the alignment film to the first substrate 3 and the second substrate 5, respectively, The alignment film is rubbed to provide a fixing force (i.e., a pretilt angle and an alignment direction). Thereafter, a spacer for keeping a cell gap constant is dispersed on the first substrate 3 and a sealing material is applied to the outer frame portion of the first substrate 3 or the second substrate 5 And pressure is applied to the first substrate 3 and the second substrate 5 to be cemented. On the other hand, the first substrate 3 and the second substrate 5 are formed of a glass substrate having a large area. In other words, since a plurality of panel regions are formed on a large-area glass substrate, and TFTs and color filter layers, which are driving elements, are formed in each of the panel regions, in order to manufacture a single liquid crystal panel, It must be processed. Then, the liquid crystal is injected into each of the liquid crystal panels processed as described above, and the liquid crystal injection hole is sealed to form the liquid crystal layer, and then the liquid crystal panel is inspected to manufacture a liquid crystal display device.

The electro-optic effect of the liquid crystal is determined by the anisotropy of the liquid crystal itself and the arrangement state of the liquid crystal molecules. Therefore, The display quality of the display device is greatly influenced. Therefore, the alignment film formation process for more effectively orienting the liquid crystal molecules is very important in relation to image quality characteristics in the liquid crystal cell process.

The alignment film is formed by a roll printing method, and FIG. 2 shows a conventional roll printing method for forming an alignment film. As shown in FIG. 2, the conventional alignment film formation uses a printing method using a plurality of rolls. That is, the alignment liquid 24 supplied between the cylindrical annealing roll 22 and the doctor roll 23 is rotated by the rotation of the annealing roll 22 and the doctor roll 23, Lt; / RTI > At this time, the supply of the alignment liquid 24 is performed by the dispenser 21 in the form of a syringe.

On the other hand, when the annealing roll 22 is in contact with a printing roll 24 having a rubber plate 25 attached thereto in a predetermined area of the surface thereof, the alignment solution on the surface of the annealing roll 22 is transferred to the rubber plate 25 do. The rubber plate 25 corresponds to the substrate 26 to which the alignment liquid is to be applied, and a mask pattern is formed to selectively print an alignment film on the substrate. The alignment liquid transferred onto the rubber plate 25 is re-transferred onto the substrate 6 to form an alignment film as the print table 27 on which the substrate 26 is mounted moves in contact with the printing roll 24. Usually, the thickness of the alignment layer is about 500 to 1000 angstroms. Even if the thickness of the same substrate is about 100 angstroms, defects such as unevenness due to unevenness in orientation may occur on the liquid crystal display (LCD) The characteristics of the screen are influenced.

However, in the above-described roll printing method, since the dispenser supplies the alignment liquid on the annealing roll while moving left and right on the upper side of the annealing roll, there is a limit to forming an alignment film having a uniform thickness. Particularly, It becomes more difficult to uniformly coat the alignment film. Moreover, since all the alignment liquid transferred to the rubber plate 25 is not transferred to the substrate, more of the alignment liquid is substantially discarded than the alignment liquid formed on the substrate, and thus there is a problem that the material cost is wasted.

Also, the roll (doctor roll, anneal roll, printing roll) must be replaced with other models depending on the size of the substrate, and the cleaning process is periodically performed, resulting in troublesome processes and inferior productivity.

Further, as the size of the substrate is increased, the sizes of the roll printing equipment (annealing rolls and printing rolls) must also be increased. Therefore, it is difficult to maintain the uniformity of the alignment film, Loses.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and it is an object of the present invention to provide a liquid crystal display element which can prevent defects due to unevenness of alignment by making the alignment film thickness uniform throughout the substrate when the alignment film is formed by the inkjet method do.

In order to achieve the above object, in the liquid crystal display element according to the present invention, the alignment liquid flows smoothly into the contact holes in order to uniformly apply the alignment liquid to the entire substrate. To this end, in the present invention, a step generated by the pixel electrode disposed around the contact hole is removed, and the alignment liquid flows into the contact hole.

At this time, in the present invention, the entire one side of the pixel electrode around the contact hole may be removed to form an inflow passage through which the alignment liquid flows, or a specific region of a predetermined width and length may be removed to form an inflow passage. By forming the inflow path with a predetermined width and length, the alignment liquid smoothly flows into the contact holes through the inflow passages, and at the same time, the penetration path of the etchant used for etching the pixel electrodes is maximally extended, It is possible to prevent infiltration of foreign matter into the apparatus. As a result, disconnection of the pixel electrode due to penetration of the etchant can be prevented.

The inlet passage may be formed in various shapes. For example, one or a plurality of the inflow passages may be formed with a predetermined width and a predetermined length to introduce the alignment liquid into the contact holes.

The common electrode and the pixel electrode are disposed on the first protective layer and the second protective layer, respectively, and the common electrode and the first protective layer are etched by the same process to form the first contact hole and the common electrode. At this time, the common electrode is over-etched due to a difference in etch rate, and is undercut under the first protective layer. When the pixel electrode is disposed on the second protective layer and connected to the drain electrode of the thin film transistor through the contact hole, the common electrode and the pixel electrode are electrically insulated by the space created by the undercut.

In the present invention, since the alignment liquid is formed by dropping the alignment liquid by the ink-jet method, it is possible to form an alignment film quickly and to apply it to a large liquid crystal display device.

In addition, in the present invention, by forming an inlet passage for introducing the alignment liquid into the pixel electrode around the contact hole so that the aligned liquid can smoothly spread into the contact hole, a uniform alignment film can be formed over the entire substrate .

In the present invention, it is possible to prevent disconnection of the pixel electrode by increasing the penetration distance of the etchant penetrating into the pixel electrode at the time of etching the pixel electrode.

1 is a cross-sectional view schematically showing a structure of a conventional liquid crystal display device.
2 is a view showing an apparatus for forming a liquid crystal display element alignment film in a roll printing system.
3A and 3B are views showing an ink-jet type liquid crystal display element alignment film forming apparatus.
4 is a plan view showing a structure of a liquid crystal display element according to a first embodiment of the present invention.
5A is a sectional view taken along the line I-I 'of FIG. 4;
5B is a cross-sectional view taken along a line II-II 'in FIG.
6A is a plan view showing a flow path of an alignment liquid in a liquid crystal display element having a structure in which a pixel electrode covers a contact hole and its periphery.
6B is a plan view showing that the spread of the alignment liquid is blocked by the step of the pixel electrode in the liquid crystal display element having the structure in which the pixel electrode covers the contact hole and the periphery.
Fig. 6C is a diagram showing a nonuniform arrangement of liquid crystal molecules due to a non-uniform alignment film; Fig.
7A to 7E are views showing a method for manufacturing a liquid crystal display element according to the first embodiment of the present invention.
8A and 8B are plan views showing a structure of a liquid crystal display element according to a second embodiment of the present invention.
FIGS. 9A and 9B are views showing a path through which an etching liquid penetrates into a pixel electrode in a structure in which pixel electrodes on one side of a contact hole are completely removed. FIG.

In the present invention, an alignment film is formed by an ink-jet method, thereby facilitating formation of an orientation film of a large liquid crystal display device, minimizing waste of alignment liquid, simplifying the process, and improving productivity.

Particularly, in the present invention, the structure of the liquid crystal display element is changed in order to uniformly form the alignment film formed by the inkjet method over the entire display element. The structure change of the liquid crystal display element can minimize a step or the like which prevents spreading when the alignment liquid dropped by the inkjet method spreads on the surface of the substrate, thereby preventing image quality deterioration due to uneven orientation. Particularly, in the present invention, the alignment film is smoothly applied in the contact hole connecting the pixel electrode to the thin film transistor, so that a uniform alignment film is formed over the entire display device.

3 is a view showing an apparatus for forming an ink jet alignment film, wherein Fig. 3A is a sectional view and Fig. 3B is a plan view.

As shown in the drawing, an inkjet alignment film forming apparatus includes an inkjet head unit 120 for dropping an alignment liquid directly on a mother substrate 100 on which a plurality of liquid crystal panels 110 are formed, (Not shown) for supplying an alignment liquid and a connection wiring portion (not shown) for mechanically connecting the inkjet head portion 120 and an alignment liquid supply portion (not shown). The inkjet head unit 120 includes at least one head 120a, and each head 120a has a plurality of holes. The amount of the alignment liquid to be applied to the substrate and the dropping position of the alignment liquid are adjusted by opening and closing the holes. In addition, the process time of the alignment layer can be controlled by adjusting the number of the holes.

When nitrogen gas (N ₂ ) is supplied to the alignment liquid supply unit (not shown) storing the alignment liquid, the pressure of the alignment liquid supply unit is increased by the nitrogen gas, and the alignment liquid is supplied to the inkjet head unit 120 ). At this time, the introduced alignment liquid is dropped onto the mother substrate 100 through the holes formed in the ink jet head unit 120. The alignment liquid ejected through the holes is dropped onto the substrate to form an alignment film having a uniform thickness.

The alignment film is formed while the stage or the head where the substrate is located is selectively moved to form the alignment film 130 in the region of the mother substrate 100 passing the inkjet head. At this time, the inkjet head unit 120 selectively supplies the alignment layer 130 on the substrate by supplying a liquid alignment liquid onto the substrate and closing a part of the holes formed in the inkjet head unit 120 during movement of the stage (not shown) . The region where the alignment film 130 is formed is a region 120 where the thin film transistor array and the color filter substrate are formed.

Since the ink jet head unit 120 is composed of at least one head 120a having a plurality of holes so that the dropping area of the alignment liquid can be freely adjusted according to the size of the mother substrate 100, As the size increases, the number of heads can be increased and the size of the substrate can be easily coped with.

4 is a view showing a structure of a liquid crystal display device according to a first embodiment of the present invention to which the ink jet alignment film forming apparatus is applied. In general, a liquid crystal display element is made up of N × M pixels arranged vertically and horizontally, but only one pixel is shown in the figure for convenience of explanation.

4, each pixel of the liquid crystal display according to the first embodiment of the present invention includes a gate line 204 to which a scan signal is applied from an external driver circuit, a data line 206 to which an image signal is applied, And a thin film transistor (T) arranged in a crossing region of the thin film transistor (T). The thin film transistor T includes a gate electrode 203 connected to the gate line 204 and a semiconductor layer 207 disposed on the gate electrode 203 and activated when a scanning signal is applied to the gate electrode 203, And a source electrode 208 and a drain electrode 209 disposed on the semiconductor layer 207.

An image signal is applied to the source 208 and the drain electrode 209 through the source electrode 208 and the drain electrode 209 as the semiconductor layer 208 is activated, A pixel electrode 210 for operating the pixel electrode 210 and a common electrode 236 for forming an electric field together with the pixel electrode 210 are disposed.

 In this case, the common electrode 236 is disposed over the entire substrate, the pixel electrode 210 is disposed in the pixel region, the common voltage is applied to the common electrode 236 over the entire substrate, An image signal corresponding to the pixel is applied. At this time, the pixel electrode 210 is disposed on an upper portion of the common electrode 236 with an insulating layer interposed therebetween, and is disposed in a plurality of strips having a predetermined width and spacing. Although the pixel electrode 210 is formed in parallel in the drawing, the pixel electrode 210 may be arranged at a certain angle in one pixel and may be formed in a symmetrical shape bent at least once.

The pixel electrode 210 is electrically connected to the drain electrode 209 through the first contact hole 229a and the second contact hole 229b. At this time, the pixel electrode 210 is disposed inside the first contact hole 229a and the second contact hole 229b, but not all around the second contact hole 229b, (229b), which will be described later in detail.

The liquid crystal display device having the above structure will be described in more detail with reference to FIGS. 5A and 5B. 5A is a cross-sectional view taken along line I-I 'of FIG. 4, and FIG. 5B is a cross-sectional view taken along a line II-II'.

5A, a gate electrode 203 is disposed on the first substrate 220 and a gate insulating layer 222 is stacked over the first substrate 220. [ Although the gate electrode 203 is formed integrally with the gate line, it may be separately formed and electrically connected. A source electrode 208 and a drain electrode 209 are disposed on the gate insulating layer 222 and a semiconductor layer 207 is formed on the gate insulating layer 222 to be activated when a signal is applied to the gate electrode 203. A first passivation layer 224 is deposited over the first passivation layer 220. At this time, a portion of the first passivation layer 224 on the drain electrode 209 is removed to form a first contact hole 229a in the first passivation layer 224, and the drain electrode 209 is exposed to the outside Exposed.

A common electrode 236 is disposed on the first passivation layer 224 and a second passivation layer 226 is deposited on the entire surface of the first substrate 220. The pixel electrode 210 is disposed on the second passivation layer 226. At this time, the pixel electrode 210 is disposed on the second passivation layer 226 at a constant width and a constant interval.

A part of the second protective layer 226 is removed to form a second contact hole 229b. At this time, the second passivation layer 226 is aligned with the first passivation layer 224 and is formed as one contact hole. The first contact hole 229a and the second contact hole 229b are formed by etching the first and second protection layers 224 and 226 at the same position, And the second protective layer 226 at the same time. The pixel electrode 210 is electrically connected to the drain electrode 209 of the thin film transistor T through the first contact hole 229a and the second contact hole 229b.

The pixel electrode 210 and the common electrode 236 are disposed between the pixel electrode 210 and the common electrode 236 with a second protective layer 226 interposed therebetween. An electric field is formed. Since the common electrode 236 is disposed over the entire pixel and the pixel electrode 210 is disposed over the common electrode 236 with a constant width and spacing between the pixel electrode 210 and the common electrode 236, An electric field parallel to the surface of the substrate 220 is formed.

Since the second passivation layer 226 and the common electrode 236 are formed by one etching process, the second passivation layer 226 does not completely cover the top and side surfaces of the common electrode 236 The side surface of the common electrode 236 is exposed to the outside. However, in the present invention, the common electrode 246 is over-etched during the etching process of the second passivation layer 226 and the common electrode 236, so that the common electrode 246 So that the common electrode 246 is disposed within a certain distance from the end of the first protective layer 224.

Accordingly, even when the pixel electrode 210 is disposed inside the first contact hole 229a and the second contact hole 229b, the pixel electrode 210 is disposed within the first contact hole 229a and the second contact hole 229b, An empty space S is formed between the electrode 210 and the common electrode 236 due to an undercut and the pixel electrode 210 and the common electrode 236 are electrically insulated by the empty space S.

As described above, in the present invention, the pixel electrode 210 and the second passivation layer 226 are etched by a single process, and the pixel electrode 210 and the common electrode 236 are electrically isolated by an empty space due to undercut , The manufacturing process can be simplified and the manufacturing cost can be reduced.

A first alignment layer 228 is formed on the first substrate 220 on which the pixel electrode 210 is formed. The first alignment layer 228 is mainly made of polyimide or polyamide, and a plurality of mirco grooves are formed on the surface by rubbing treatment. Such fine grooves cause alignment regulating force in the alignment film to align the liquid crystal molecules in contact with the alignment film in a certain direction. The reason why the liquid crystal molecules are oriented in a certain direction due to the alignment regulating force of the alignment film is that the liquid crystal molecules are fixed to the surface of the alignment film by the alignment regulating force of the alignment film (for this reason, the anchoring energy is also referred to as surface fixing force).

The second substrate 230 is provided with a black matrix 232 for blocking transmission of light to the image non-display area and a color filter layer 234 for realizing colors. 2 substrate 230. In this case, The black matrix 232 is disposed in a region between a pixel and a pixel and in a thin film transistor forming region to block leakage of light to the region. The color filter layer 234 includes R, G, and B color filter layers, Color.

A second alignment layer 238 is disposed on the color filter layer 234. Like the second alignment film 238 and the first alignment film 228, is formed of polyimide or polyamide and is rubbed in a predetermined direction to align the liquid crystal molecules of the liquid crystal layer 240 in a specific direction. At this time, the first alignment layer 228 and the second alignment layer 238 may be parallel or perpendicular to each other in the rubbing direction.

The first passivation layer 224 on the drain electrode 209 is removed to form the first contact hole 229a and the second passivation layer 226 on the top of the drain electrode 209 is etched, 2 contact holes 229b are formed. The lower common electrode 236 is etched when the second contact hole 229b is etched so that the common electrode 236 is undercut and disposed within a predetermined distance from the wall surface of the second contact hole 229b, The pixel electrode 210 disposed on the second passivation layer 226 is electrically insulated from the common electrode 236 by a space formed by the undercut.

A part of the pixel electrode 210 is partially formed in the first contact hole 229a and the second contact hole 229b and in the second protective layer 229a around the first contact hole 229a and the second contact hole 229b The pixel electrode 210 may be electrically connected to the drain electrode 209 through the first contact hole 229a and the second contact hole 229b.

However, in the present invention, the pixel electrode 210 is not disposed around the entirety of the second protection layer 226 above the first contact hole 229a and the second contact hole 229b, The left area of the hole 229b and the lower area of the second contact hole 229b in FIG. 4) are removed so that the pixel electrode 210 is not disposed above the second protective layer 226 in the corresponding area. That is, one side of the pixel electrode 210 is removed from the square pixel electrode 210 disposed on the second protection layer 226 around the first contact hole 229a and the second contact hole 229b, The pixel electrode 210 is not formed in the second passivation layer 226 of the first passivation layer 226 but only in the first contact hole 229a and the second contact hole 229b.

The absence of the pixel electrode 210 on one side (one side) of the second contact hole 229b and the pixel electrode 210 on the second passivation layer 226 of the corresponding region, In order to smoothly apply the alignment liquid into the first contact holes 229a and the second contact holes 229b at the time of forming the alignment film to form a uniform alignment film over the entire liquid crystal display element And will be described in more detail with reference to the drawings.

6A and 6B are a plan view and a sectional view, respectively, of a structure in which pixel electrodes 210 are formed around a second contact hole 229b on the second protective layer 226, and FIG. 6C is a cross- Fig. 5 is a diagram showing the orientation of liquid crystal molecules. Fig.

As shown in FIG. 6A, in the liquid crystal display device of this structure, the pixel electrode 210 is disposed not only within the second contact hole 229b but also over the entire outer region around the second contact hole 229b.

On the other hand, when the first alignment film 228 is applied, the alignment liquid is dropped onto the first substrate 220 having the structure shown in FIG. 6A by using the alignment film forming apparatus shown in FIGS. 3A and 3B, and then cured. The alignment liquid dropped on the first substrate 220 is spread on the first substrate 220 to form the first alignment film 228 over the entire first substrate 220. [ Therefore, in order to form a uniform first alignment layer 228 over the entire surface of the first substrate 220, the alignment liquid must be uniformly spread over the entire surface of the first substrate 220.

The alignment liquid dropped through the alignment film forming apparatus spreads out of the area dropped on the first substrate 220. At this time, since the same level difference as that of the pixel electrode 210 exists on the first substrate 220, the alignment liquid flows first along the step difference and gradually spreads over the entire first substrate 220 beyond the step difference.

In order to form a uniform first alignment layer 228 in the first and second contact holes 229a and 229b as well as the pixel electrode 210 and the second passivation layer 226, It must be uniformly applied to the first contact hole 229a and the second contact hole 229b. However, as shown in FIG. 6A, the alignment liquid spreading around the second contact holes 229b flows along the step of the pixel electrode 210. That is, the step of the pixel electrode 210 serves as a passage through which the alignment liquid flows, and the alignment liquid spreads along the step of the pixel electrode 210 covering the second contact hole 229b.

6B, when the alignment liquid spreads along the step of the pixel electrode 210, the alignment liquid is separated from the first and second contact holes 229a and 229a by the step of the pixel electrode 210, (229b). Accordingly, the application of the alignment liquid to the first contact holes 229a and the second contact holes 229b is not smoothly performed. When the first alignment film 228 is formed, the first contact holes 229a and the second contact holes 229b The thickness of the first alignment layer 228 in the second contact hole 229b is smaller than the thickness of the first alignment layer 228 in the other region so that a uniform first alignment layer 228 can not be formed, The first alignment layer 228 may not be formed in the first and second contact holes 229a and 229b.

The thickness of the first alignment film 228 of the partial region b (for example, the first contact hole 229a and the second contact hole 229b) is different from the thickness of the other region a, The alignment regulating force of the first alignment film 228 in the region b is less than the thickness of the first alignment film 228 in the region a and the first alignment film 228 is not formed in the partial region b, 228), the alignment direction (or pretilt angle) of the liquid crystal molecules 241b in the b region and the alignment direction (or the pretilt angle) of the liquid crystal molecules 241a in the a region are different from each other. Therefore, when the image according to the image signal is realized through the region a, the light transmissivity of the region b and the region a are different from each other, so that light leakage occurs through the region b due to the difference in light transmittance. A defective image quality is caused.

However, in the present invention, as shown in FIGS. 5A and 5B, the pixel electrode 210 on one side (one side) of the pixel electrode 210 disposed around the second contact hole 229b is removed, The pixel electrode 210 is not formed in the second passivation layer 226 and the pixel electrode 210 is formed only in the second contact hole 229b. Therefore, when the alignment liquid spreads, the alignment liquid smoothly flows into the first contact holes 229a and the second contact holes 229b without being blocked by the step of the pixel electrode 210. [ That is, in the present invention, by forming the alignment liquid inflow region into which the alignment liquid flows into the first contact holes 229a and the second contact holes 229b, a first alignment film having a uniform thickness over the entire surface of the first substrate 220 (228).

On the other hand, in the figure, the alignment liquid inflow region is formed in a lower region (that is, a region adjacent to the gate line 203) of the second contact hole 229b, but the present invention is not limited to such a structure. The alignment liquid inflow region is for smoothly flowing into the first contact holes 229a and the second contact holes 229b when the alignment liquid spreads on the substrate, and any structure is possible as long as such an object can be achieved . For example, the pixel electrode on the upper portion (that is, the pixel center side) of the pixel electrode 210 above the second passivation layer 226 around the second contact hole 229b is removed so that the liquid- And the pixel electrodes on the side surface (that is, the data line side and the opposite side) of the pixel electrode 210 above the second passivation layer 226 around the second contact hole 229b are removed so that the liquid- It may be formed in this region.

Further, even when the pixel electrodes around the contact holes 229a and 229b are formed in a shape other than a rectangular shape, for example, a circular shape, an alignment liquid inflow region can be formed. In this case, the alignment liquid inflow region may be formed by removing a predetermined region in the direction in which the alignment liquid spreads when forming the alignment film, for example, each quadrant (upper and lower, left and right) of the circular pixel electrode.

Hereinafter, a method of manufacturing a liquid crystal display device according to a first embodiment of the present invention will be described in detail with reference to the drawings.

7A to 7E are views showing a method of manufacturing a liquid crystal display element according to the first embodiment of the present invention.

First, as shown in FIG. 7A, a gate electrode 203 is formed on a transparent first substrate 220 such as glass or plastic. Although not shown in the drawing, a gate line is formed when the gate electrode 203 is formed. The gate electrode 203 and the gate line are formed by depositing a metal such as Al or an Al alloy on the first substrate 220 by evaporation or sputtering and then performing a photolithography process using a mask And may be formed by patterning.

Next, a gate insulating layer 222 is formed by depositing SiOx, SiNx, or the like over the entire first substrate 220 on which the gate electrode 203 is formed by a CVD (Chemical Vapor Deposition) process.

Thereafter, a semiconductor layer 207 is formed on the gate insulating layer 222 and a source electrode 208 and a drain electrode 209 are formed on the semiconductor layer 312. In the case of forming the amorphous semiconductor layer, the semiconductor layer 207 is formed by depositing amorphous silicon by CVD method and then patterning the amorphous silicon layer. In the case of forming the crystalline semiconductor layer, the amorphous silicon layer And then crystallizing or laminating crystalline silicon. The source electrode 208 and the drain electrode 209 are formed by depositing a metal such as Cr, Mo, Al, Al alloy or the like by vapor deposition or sputtering, and then patterning it by a photolithography process using a mask. Although not shown in the drawings, a data line is also formed when the source electrode 208 and the drain electrode 209 are formed.

A first passivation layer 224 is formed on the first substrate 220 on which the thin film transistor is formed and then etched to form a first contact hole 229a on the first passivation layer 224 above the drain electrode 209 ). The first passivation layer 224 may be formed by laminating an inorganic insulating material such as SiOx or SiNx by CVD or by applying an organic insulating material such as photo acryl.

7B, a conductive layer 236a made of a transparent conductive material such as ITO (Indium Tin Oxide) or IZO (Indium Zinc Oxide) and an insulating layer A photoresist pattern 260 is formed on the insulating layer 226a by a photomask. At this time, a portion of the insulating layer 226a including the first contact hole 229a is exposed to the outside by the development of the photoresist pattern 260. [ Then, the insulating layer 226a and the conductive layer 236a are etched by the photoresist pattern 260. Then,

The insulating layer 226a and the conductive layer 236a are removed by the etching to form the common electrode 236 and the second passivation layer 226 and the second contact hole 229b, . Since the insulating layer 226a and the conductive layer 236a have different etching rates, when the insulating layer 226a and the conductive layer 236a are etched by one etching process, the conductive layer 236a is overetched So that the common electrode 2360 is undercut under the second protective layer 226.

7D, a conductive layer 210a made of a transparent conductive material such as ITO or IZO is deposited over the entire surface of the first substrate 220 and etched to form the pixel electrode 210, 3, an orientation liquid such as a polyimide or polyamide is applied to a thickness of about 500-1000 A to form a first alignment layer 228 over the entire surface of the first substrate 200.

The pixel electrode 210 is disposed to completely cover the second contact hole 229b, but is disposed along three sides of the periphery of the second contact hole 229b, not the entire periphery of the second contact hole 229b. That is, the pixel electrode 210 is not formed around the one side of the second contact hole 229b, and the pixel electrode 210 does not have a step in this region.

The first alignment film 228 is formed by dropping the alignment liquid by the alignment film forming apparatus shown in FIG. 3, spreading the aligned alignment liquid over the entire surface of the first substrate 220, and then curing. Since the alignment liquid spreads into the second contact holes 229b through the alignment liquid inflow region and uniformly spreads over the entire first substrate 220 including the contact holes 229a and 229b, ) Can be formed. In addition, the first alignment layer 228 is subjected to rubbing treatment to give a set alignment direction.

7E, a metal such as Cr or CrOx is stacked on the second substrate 230 and etched to form a black matrix 232 in the image non-display area. Then, (R), green (G), and blue (B) pigments or dyes are deposited and etched to form a color filter layer 234 over the entire surface. Then, an alignment liquid is applied onto the color filter layer 234 by an alignment film forming apparatus and cured to form a second alignment film 238. [ Although not shown in the drawing, a planarization layer made of an organic insulating material may be formed on the color filter layer 234 before the second alignment film 238 is formed.

Next, a liquid crystal layer 240 is formed between the first substrate 220 and the second substrate 230 to complete a liquid crystal display device.

As described above, in the present invention, since the pixel electrode 210 on one side around the contact holes 229a and 229b is removed to smoothly flow the alignment liquid into the contact holes 229a and 229b when the alignment liquid is applied, So that the first alignment layer 228 is formed to have a uniform thickness over one substrate 220. As a result, the light leakage phenomenon caused by the unevenness of the first alignment film 228 can be prevented.

8A and 8B are views showing a structure of a liquid crystal display device according to a second embodiment of the present invention. Since the structure of this embodiment is similar to that of the first embodiment, description of the same structure will be omitted and only other structures will be described in detail.

As shown in Fig. 8A, in the liquid crystal display element of this structure, the second contact hole 329b and the pixel electrode 310 are arranged around the second contact hole 329b. In the first embodiment, all the pixel electrodes on one side (or one side) of the second contact holes are removed so that the pixel electrodes are not disposed on one side of the rectangular second contact holes, pixel electrodes are formed only inside the contact holes, The pixel electrode 310 surrounding the second contact hole 329b is filled with the alignment liquid inflow passages 310a and 310b formed in the grooves having the set width d, Is formed. At this time, the grooves are formed along the orientation liquid spreading direction in which the entrance thereof spreads all over the liquid crystal tabular element when the alignment film is formed. It is also preferable that the extending direction of the grooves is also arranged substantially parallel to the orientation liquid spreading direction.

That is, compared to the first embodiment, in this embodiment, the inflow passage of the alignment liquid introduced into the second contact holes 329b is formed to be small. The structure of the first embodiment, which is shown in Figs. 9A and 9B, Explain.

9A, since the pixel electrodes 210 on one side of the second contact holes 229b are all removed in the first embodiment, the pixel electrodes 210 are formed in the second protective layer 226 and common The second protection layer 226 and the common electrode 236 are exposed to the outside while covering the side surface of the electrode 236. Therefore, when the conductive layer is etched by the etching liquid when the pixel electrode 210 is formed, the etching liquid penetrates through the space S of the exposed region.

9B, the penetrated etchant penetrates the pixel electrode 210 along the edge of the pixel electrode 210, thereby breaking the pixel electrode 210. When the pixel electrode 210 is disconnected, an image signal supplied through the thin film transistor is not applied to the pixel electrode 210 of the corresponding pixel, and the corresponding pixel becomes a dark spot, resulting in a defective liquid crystal display element.

As described above, in the first embodiment, the etchant penetrates into the removed region to flow the alignment liquid into the second contact holes 229b, and then, along the edge region of the pixel electrode 210, Infiltration. If one side of the pixel electrode 210 is not removed, disconnection of the pixel electrode 210 due to penetration of the etchant does not occur. However, in this case, a light leakage phenomenon occurs due to nonuniform application of the alignment film.

In this embodiment, it is possible to uniformly form the alignment film and to prevent disconnection of the pixel electrode 310 due to penetration of the etchant. For this, in this embodiment, the pixel electrode 310 around the second contact hole 329b is removed to form an alignment liquid inflow passageway that flows into the second contact hole 329b, and at the same time, the alignment liquid inflow passageway is minimized The etchant penetrating path along the edge of the pixel electrode 310 is maximized to prevent the etchant from penetrating into the pixel electrode 310.

8A, the pixel electrode 310 around the second contact hole 329b on the second passivation layer 326 is removed, and the entire one side of the second contact hole 329b is removed Only the predetermined region is removed to form a groove-like inflow passage 310a into which the alignment liquid having the width (d) and the length (l) set in the pixel electrode 310 flows. The alignment liquid flowing through the edge step of the pixel electrode 310 flows into the second contact hole 329b through the inflow passageway 310a when the alignment liquid is dripped and spreading so that the contact holes 329a and 329b The alignment liquid can be uniformly applied over the entire surface of the first substrate 320 including the first substrate 320.

In this embodiment, the etching liquid flows into the pixel electrode 310 along the edge of the pixel electrode 310 when the pixel electrode 310 is etched, and the etchant flows into the pixel electrode 310 through the inflow path 310a . In this embodiment, since the inflow passages 310a are formed to have a constant width d and a length l, the etchant infiltrated into this area is formed along the edges of the inflow passages 310a by the length of the pixel electrodes 310 And then penetrates into the pixel electrode 310 along the outer edge of the pixel electrode 310 again.

Therefore, compared to the first embodiment, since the penetration distance of the etchant increases (2 L + (the length of one side of the pixel electrode excluding the width of the inflow path of the side where the inflow path is formed)), It becomes difficult to penetrate. Even when a part of the etchant penetrates into the pixel electrode 310, the amount thereof is minimized and the pixel electrode 310 can not be disconnected.

Although the inlet passage 310a has a rectangular shape having a specific width (a) and a length (l), the inlet passage 310a need not have a specific shape. The purpose of the inflow path 310a is to increase the infiltration distance of the etchant flowing into the pixel electrode 310 along the edge of the pixel electrode 310 while flowing the alignment liquid into the second contact hole 329b Any shape can be used as long as it can achieve this purpose. For example, the inflow passage 310a may be formed by a zigzag straight line at a certain angle, and may have a curved shape with a predetermined curvature and bent a plurality of times.

Further, the inflow passage 310a need not be limited to a specific position. Although the inflow path 310a is formed on the lower side of the rectangular pixel electrode 310 around the second contact hole 329b in the figure, the inflow path 310a may be formed at various positions such as a side surface and a top surface. There will be.

In the case of the circular shape of the pixel electrode 310, the inflow passage 301a may be removed to the boundary of the contact hole 329b in the circumferential direction by the set width to form the groove-like inflow passage 310a. At this time, although it may be formed anywhere on the circumference in the circular diameter direction of the inflow passage 310a, it is preferable that it is provided along the spreading direction of the alignment liquid when forming the alignment film.

As shown in FIG. 9B, a plurality of the inflow passages 310a may be formed. As described above, the purpose of the inflow path 310a is to cause the alignment liquid to flow into the contact holes 329a and 329b, to penetrate the pixel electrode 310 along the edge of the pixel electrode 310, This purpose is more easily achieved by forming a plurality of the inflow passages 310a since it is for increasing the distance. That is, by forming a plurality of the inflow passages 310a, the infiltration of the alignment liquid into the second contact holes 329b is smooth, and the etchant infiltrated by the inflow passages 310a flows into the edges of the plurality of inflow passages 310a The penetration distance of the etchant is increased and the disconnection of the pixel electrode 310 can be prevented.

Although a plurality of inflow passages 310a are formed in a specific shape in the drawing, the inflow passages 310a may be formed in various shapes such as a zigzag linear shape or a serpentine curved shape. Although a plurality of inflow passages 310a are formed on the specific one side (that is, the lower side) of the square-shaped pixel electrode 310 around the second contact hole 329b in the figure, (I. E., Top side or side) and may be formed on two or more sides. When a plurality of inflow passages 310a are formed on two or more sides, the inflow passages 310a formed on each side may be formed in the same shape or in different shapes.

Although the present invention has been described with a specific structure for the sake of convenience, it is not intended to limit the scope of the present invention. For example, although the structure of the pixel electrode and the common electrode is described in the above-described detailed structure in a specific structure, the present invention is not limited to the pixel electrode and the common electrode having such a specific structure. The present invention relates to a liquid crystal display device, and can be applied to liquid crystal display devices having all the structures provided with an alignment film.

In addition, although many details are described in the above description, it should be interpreted as an example of preferred embodiments rather than limiting the scope of the invention. Therefore, the invention should not be construed as limited to the embodiments described, but should be determined by equivalents to the appended claims and the claims.

120, 130, 220, 230: substrate 210, 310: pixel electrode
224, 324: first protective layer 226, 326: second protective layer
229a, 229b, 329a, 329b: contact holes 236, 336:
228, 238, 328, 338:

Claims (14)

A substrate including a plurality of pixels;
A thin film transistor arranged in each pixel;
A common electrode and a pixel electrode arranged in each pixel;
A contact hole disposed in the pixel to connect the thin film transistor and the pixel electrode; And
And an alignment layer disposed over the entire substrate,
Wherein the pixel electrode is disposed inside the contact hole and around the contact hole, and the pixel electrode around the contact hole is connected to the contact hole to have an inlet passage through which the alignment liquid flows when the alignment layer is formed. The thin film transistor according to claim 1,
A gate electrode disposed on the first substrate;
A gate insulating layer disposed on the gate electrode;
A semiconductor layer disposed on the gate insulating layer; And
And a source electrode and a drain electrode disposed on the semiconductor layer. 3. The method of claim 2,
A first passivation layer covering the thin film transistor; And
And a second protective layer disposed between the common electrode and the pixel electrode. The liquid crystal display according to claim 3, wherein the contact hole is formed in the first passivation layer and the second passivation layer above the drain electrode. The liquid crystal display element according to claim 4, wherein the pixel electrode is disposed above the second passivation layer around the contact hole. The liquid crystal display element according to claim 5, wherein the alignment liquid inflow passages are formed on at least one side of four sides of the square-shaped pixel electrodes around the contact holes. The liquid crystal display element according to claim 5, wherein the alignment liquid inflow passages are formed with a predetermined width in the pixel electrodes around the contact holes. The liquid crystal display element according to claim 7, wherein the alignment liquid inflow passages are grooves provided at predetermined widths in the pixel electrodes around the contact holes. The liquid crystal display element according to claim 8, wherein an inlet of the groove is disposed along a spreading direction of the alignment liquid. The liquid crystal display element according to claim 7, wherein the alignment liquid inflow passage has a rectangular shape, a zigzag shape, or a curved shape. The liquid crystal display element according to claim 7, wherein a plurality of alignment liquid inflow passages are provided on the pixel electrodes. The liquid crystal display according to claim 4, wherein the common electrode is disposed on the first passivation layer, the pixel electrode is disposed on the second passivation layer, and the common electrode is undercut to be electrically insulated from the pixel electrode by the space. A substrate including a plurality of pixels;
A thin film transistor arranged in each pixel;
A first protective layer disposed on the substrate;
A common electrode disposed over the first passivation layer of the pixel;
A second protective layer disposed on the common electrode;
A pixel electrode disposed on the second passivation layer and connected to the thin film transistor through a contact hole formed in the first passivation layer and the second passivation layer; And
And an alignment layer disposed over the entire substrate,
Wherein the pixel electrode is provided with an inflow passageway for introducing an alignment liquid of the alignment layer into the contact hole, the inflow passageway maximizing the infiltration distance of the etchant penetrating along the edge of the pixel electrode. 14. The liquid crystal display according to claim 13, wherein the inflow passage has a rectangular shape, a zigzag shape or a curved shape with a predetermined width and a predetermined length.

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