KR101157226B1 - Liquid crystal display and method for manufacturing lcd - Google Patents

Abstract

The present invention discloses a liquid crystal display device and a method of manufacturing the same, which prevent light leakage and improve contrast ratio by minimizing a step difference of a contact area in a pixel area of a liquid crystal display device. The disclosed invention includes depositing and etching a metal film on a transparent insulating substrate to form a gate electrode, a gate wiring, a common wiring, a first common electrode and a first storage electrode; Sequentially applying and depositing a gate insulating film, a semiconductor film, and a metal film on the insulating substrate on which the gate electrode and the like are formed, and etching the same to form a source / drain electrode, a data line, a second storage electrode, and a channel layer; Forming a photoresist pattern for forming a contact hole on the passivation layer by applying a passivation layer on the insulating substrate on which the source / drain electrodes and the like are formed, and then exposing and developing the photoresist layer; And forming a contact hole along the photoresist pattern, depositing a transparent metal film on the protective film on which the photoresist pattern is formed, and then forming a pixel electrode, a contact portion, and a second common electrode according to a lift-off process. It is characterized by.

LCD, IPS, Slit, Step, Light Leaks

Description

Liquid crystal display and its manufacturing method {LIQUID CRYSTAL DISPLAY AND METHOD FOR MANUFACTURING LCD}

1 is a diagram illustrating a pixel structure of a transverse electric field type liquid crystal display device according to the related art.

2 is a cross-sectional view taken along the line AA ′ of FIG. 1.

3 is a diagram illustrating a pixel structure of a transverse electric field type liquid crystal display device according to an exemplary embodiment of the present invention.

4 is a cross-sectional view taken along the line II ′ of FIG. 3.

5 is a cross-sectional view taken along the line II ′ of FIG. 3;

6 is a cross-sectional view taken along the line K-K ′ of FIG. 3.

* Description of the symbols for the main parts of the drawings *

100: glass substrate 101: gate electrode

102: gate insulating film 103: common wiring

103a: first common electrode 103b: second common electrode

104: channel layer 105a: source electrode

105b: drain electrode 106: ohmic contact layer

107: first storage electrode 107a: pixel electrode

107b: second storage electrode 109: protective film                 

112: contact portion

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display (LCD), and more particularly, by minimizing a step difference in a contact area in a pixel area of a liquid crystal display, preventing light leakage and contrast ratio. The present invention relates to a liquid crystal display device and a method of manufacturing the same.

In general, as the modern society changes to the information socialization, the importance of the liquid crystal display module, which is one of the information display devices, is gradually increasing. Cathode ray tube (CRT), which is widely used so far, has many advantages in terms of performance and cost, but has many disadvantages in terms of miniaturization or portability.

In order to secure the shortcomings of the CRT, liquid crystal displays have been developed that can realize light and small, high brightness, large screen, low power consumption and low cost.

The liquid crystal display (LCD) has excellent display resolution than other flat panel display devices and exhibits a response speed that is higher than that of a CRT when implementing a moving image.

In general, the driving principle of the liquid crystal display device uses the optical anisotropy and polarization of the liquid crystal.

Since the liquid crystal is thin and long in structure, the liquid crystal has directivity in the arrangement of molecules, and the direction of the molecular arrangement can be controlled by artificially applying an electric field to the liquid crystal.

When the molecular alignment direction of the liquid crystal is arbitrarily adjusted, the molecular arrangement of the liquid crystal is changed, and light polarized by optical anisotropy may be arbitrarily modulated to express image information.

Currently, an active matrix liquid crystal display device (AM-LCD: below Active Matrix LCD, abbreviated as liquid crystal display device) in which a thin film transistor and pixel electrodes connected to the thin film transistor are arranged in a matrix manner has the best resolution and video performance. It is attracting attention.

The liquid crystal display includes a color filter substrate on which a common electrode is formed, an array substrate on which a pixel electrode is formed, and a liquid crystal filled between two substrates. The liquid crystal display is one of active matrix liquid crystal display devices that are mainly used and are twisted nematic (TN). nematic) type liquid crystal display device. The twisted nematic method is a method of driving the liquid crystal director by installing electrodes on two substrates, arranging the liquid crystal directors to be twisted by 90 °, and then applying a voltage to the electrodes.

However, the TN (twisted nematic mode) liquid crystal display has a big disadvantage that the viewing angle is narrow.

Recently, researches on liquid crystal displays employing various new methods have been actively conducted to solve the narrow viewing angle problem. In this method, an in-plane switching mode (IPS) or an OCB is used. Optically compensated birefrigence mode.

Among these, the transverse electric field type liquid crystal display includes two electrodes formed on the same substrate in order to drive the liquid crystal molecules in a horizontal state with respect to the substrate, and a voltage is applied between the two electrodes so as to be horizontal with respect to the substrate. Generate an electric field in the direction. In other words, the long axis of the liquid crystal molecules does not stand on the substrate.

For this reason, the change of the birefringence of the liquid crystal with respect to the visual direction is small, and the viewing angle characteristic is much superior to the conventional TN type liquid crystal display device.

Hereinafter, a structure of a transverse electric field type liquid crystal display device according to the related art will be described in detail with reference to the accompanying drawings.

1 is a diagram illustrating a pixel structure of a transverse electric field type liquid crystal display device according to the related art.

As shown in FIG. 1, the gate line 11 applying the driving signal and the data line 13 applying the data signal are vertically intersected to define a unit pixel area.

On the unit pixel area, a plurality of common electrodes 3a branched in a slit form from a common wiring 3 to which a common signal is applied, and a storage electrode 7 forming a storage capacitance together with the common wiring 3. The plurality of pixel electrodes 7a branched in the slit form are alternately arranged alternately at predetermined intervals.

The thin film transistor TFT, which is a switching element, is disposed on an area where the gate line 11 and the data line 13 vertically intersect.

The thin film transistor may include a gate electrode 1 branched from the gate line 11, a source electrode 5a branched from the data line 13 while positioned above the gate electrode 1, and the source electrode ( It is composed of a drain electrode 5b which is in electrical contact with the pixel electrode 7a while facing 5a).

In the IPS mode LCD having the above structure, the pixel electrode 7a having the slit structure and the common electrode 3a are alternately disposed on the lower substrate to form a transverse electric field, and the pixel electrode The liquid crystal molecules are arranged horizontally in accordance with the transverse electric field direction formed between the 7a and the common electrode 3a.

Since the liquid crystal molecules are arranged horizontally as described above, the viewing angle characteristic is excellent and an excellent image is displayed.

FIG. 2 is a cross-sectional view taken along the line AA ′ of FIG. 1.

As shown in FIG. 2, a metal film is deposited on a glass substrate 10 made of a transparent insulating substrate, and then the metal film is etched by a photolithography process to form a gate electrode 1 and a slit common electrode ( Simultaneously form 3a).

The gate insulating film 2 is coated on the glass substrate 10 on which the gate electrode 1 and the common electrode 3a are formed, and then amorphous silicon and doped amorphous silicon are coated on the gate insulating film 2. Next, a photolithography process is performed to form the channel layer 6.

Then, a metal film is deposited and etched on the glass substrate 10 on which the channel layer 6 is formed to form source / drain electrodes 5a and 5b and a data line (not shown).

The first passivation layer 8 is coated on the glass substrate 10 formed on the source / drain electrodes 5a and 5b and then etched to form a contact hole.                         

A transparent metal film (ITO) is deposited on the glass substrate 10 having the contact hole and is etched to form a slit pixel electrode 7a, and then a second passivation layer 9 is formed on the glass substrate ( Apply on the whole area of 10).

However, the liquid crystal display device having the IPS structure having the above structure has a disadvantage in that the manufacturing cost is increased because the array substrate is manufactured by performing the mask process 5 or 4 times.

In addition, since the conventional transverse electric field type pixel electrode and the common electrode are alternately arranged in a slit form, there is a disadvantage in that the liquid crystal molecules oriented at the top and the bottom of the unit pixel area are not symmetrical, causing light leakage.

According to the present invention, a common electrode and a pixel electrode formed in a unit pixel region are formed in a folded structure while a transverse electric field type liquid crystal display device is manufactured according to a three mask process.

In addition, it is an object of the present invention to provide a liquid crystal display device and a method of manufacturing the same, which reduces manufacturing costs by minimizing the level difference between the contact areas of the wirings and the electrodes and improves light leakage defects.

In order to achieve the above object, the liquid crystal display device manufacturing method according to the present invention,

Depositing and etching a metal film on the transparent insulating substrate to form a gate electrode, a gate wiring, a common wiring, a first common electrode, and a first storage electrode;

Sequentially applying and depositing a gate insulating film, a semiconductor film, and a metal film on the insulating substrate on which the gate electrode and the like are formed, and etching the same to form a source / drain electrode, a data line, a second storage electrode, and a channel layer;

Forming a photoresist pattern for forming a contact hole on the passivation layer by applying a passivation layer on the insulating substrate on which the source / drain electrodes and the like are formed, and then exposing and developing the photoresist layer; And

Forming a contact hole along the photoresist pattern, depositing a transparent metal film on the passivation layer on which the photoresist pattern is formed, and then forming a pixel electrode, a contact portion, and a second common electrode according to a lift-off process; It features.

The source / drain electrode, the data line, the second storage electrode, and the channel layer may be formed by a diffraction exposure process, and the pixel electrode, the contact portion, and the second common electrode may be transparent metal, and the contact portion may be formed of the drain electrode. The first storage electrode is formed to be electrically connected.

In the liquid crystal display device according to the present invention,

Board;

Data lines, gate lines, and common lines intersected on the substrate to define a unit pixel area;

A switching element disposed in an area where the data line and the gate line cross each other;

First common wiring branched from the common wiring and formed in a direction parallel to the data wiring;                     

A pixel electrode and a second common electrode which are alternately disposed on the unit pixel area at predetermined intervals;

A first storage electrode connected to the drain electrode of the switching element; And

And a second storage electrode overlapping the first storage electrode with the insulating layer interposed therebetween.

Here, the pixel electrode and the second common electrode is a slit structure, the pixel electrode and the second common electrode is a transparent metal, and further comprising a contact portion electrically connecting the drain electrode and the first storage electrode of the switching element. It features.

The second storage electrode is electrically connected to any one of the second common electrodes, and the pixel electrode is electrically connected to the first storage electrode.

According to the present invention, the common electrode and the pixel electrode formed in the unit pixel region are formed in a bent structure while the transverse electric field type liquid crystal display device is manufactured according to the three mask process.

In addition, the manufacturing cost is lowered and the light leakage defect is improved by minimizing the step difference between the contact areas of the wirings and the electrodes.

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

3 is a diagram illustrating a pixel structure of a transverse electric field type liquid crystal display device according to an exemplary embodiment of the present invention.

As illustrated in FIG. 3, the gate line 111 applying the driving signal and the data line 113 applying the data signal are vertically intersected to define a unit pixel area.

Here, in the present invention, the data line 113 is formed to have a bent structure at a predetermined angle in the center region in the unit pixel region. This is because the alignment direction of the liquid crystal molecules is vertically symmetrical to realize a wide viewing angle. to be.

On the unit pixel area, a common wiring 103 for applying a common signal is formed in a parallel direction while facing the gate wiring 111. One of the two first common electrodes 103a branched from the common line 103 is formed in a direction parallel to the data line 113, and the other is a direction parallel to an area adjacent to the data line 113. It is formed.

In addition, a first storage electrode 107 of a storage capacitor is formed in a direction parallel to the gate wiring 111 in a unit pixel area adjacent to the gate wiring 111, and the first storage electrode 107 is disposed in the unit pixel region. The second storage electrode 107b overlapping with each other to form a storage capacitor is formed.

The second storage electrode 107b is formed together when the data line 113 is formed.

The thin film transistor TFT, which is a switching element, is disposed on an area where the data line 113 and the gate line 111 vertically cross each other.                     

The thin film transistor includes a gate electrode 101 branched from the gate line 111, a source electrode 105a positioned above the gate electrode 101, and branched to the data line 113, and the source electrode. It is comprised by the drain electrode 105b which electrically contacts with the said 1st storage electrode 107, facing 105a.

The first storage electrode 107 is electrically contacted with a plurality of pixel electrodes 107a disposed in a unit pixel area in a slit structure.

The second common electrodes 103b electrically contacting the common wiring 103 and the first common electrode 103a are alternately arranged at a predetermined interval with the pixel electrodes 107a in the unit pixel area. Formed.

In addition, the drain electrode 105b of the thin film transistor is electrically connected to the first storage electrode 107 and the contact portion 112, and has a slit structure for a data signal applied from the data line 113. It applies to the electrode 107a.

That is, the first storage electrode 107 may be regarded as a pixel electrode 107a.

In addition, one of the second common electrodes 103b electrically connected to the first common electrode 103a may be in electrical contact with the second storage electrode 107b, so that the first storage electrode 107 Together they form a storage capacitance.

That is, the second storage electrode 107a receives a common signal.

4 is a cross-sectional view taken along the line II ′ of FIG. 3.

As shown in FIG. 4, a gate metal film is deposited on the glass substrate 100, which is a transparent insulating substrate, and the metal film is etched by a photolithography process to form a gate wiring, a gate electrode 101, a common wiring, and a first common electrode. And a first storage electrode 107.

In this case, the first storage electrode 107 is formed in an independent form not electrically contacted with the common wiring and the first common electrode.

When the gate electrode 101 is formed on the glass substrate 100 as described above, the gate insulating film 102, the amorphous silicon film, the doped amorphous silicon film, and the source / drain metal film are successively deposited and then subjected to the diffraction exposure process. Accordingly, the channel layer 104, the ohmic contact layer 106, the source / drain electrodes 105a and 105b, the data line, and the second storage electrode are simultaneously formed.

In this case, in order to form the pixel electrode 107a according to the three mask process, the channel layer 104 formed on the pixel region is successively removed to expose the gate insulating layer 102.

When the source / drain electrodes 105a and 105b are formed on the glass substrate 100 as described above, the protective film 109 is coated on the entire area of the glass substrate 100 and a part of the drain electrode 105b is formed. Expose

In addition, in order to form the pixel electrode 107a on the pixel area, the glass layer 100 is etched by removing the channel layer 104 (amorphous silicon and doped amorphous silicon) to expose the gate insulating layer 102. ) To the outside.

When the contact hole is formed on the passivation layer 109 as described above, the ITO transparent metal layer is deposited without removing the photoresist formed on the passivation layer 109 according to a lift-off process.

In the transparent metal deposited on the photoresist patterned on the passivation layer 109, an etchant solution penetrates through the lift-off process to separate the transparent metal together with the photoresist, leaving only the pixel electrode 107a patterned in the pixel region. .

When the lift-off process is performed according to the three mask process as described above, as shown in the drawing, the drain electrode 105b and the first storage electrode 107 are electrically connected by the contact portion 112 which is a transparent metal.

In addition, in the contact hole process of the passivation layer 109, the gate insulating layer 102 is removed to form a pixel electrode 107a by depositing a transparent metal layer in an area where the glass substrate 100 is exposed.

The contact portion 112 electrically connects the first storage electrode 107 and the drain electrode 105b formed on the glass substrate 100 together with the gate electrode 101 to be applied from the source electrode 105a. The data signal to be applied is applied to the first storage electrode 107.

The first storage electrodes 107 are electrically connected to the pixel electrode 107a formed of a transparent metal. In the present invention, the pixel electrode 107a and the first storage electrode 107 are electrically connected to each other. By minimizing the step, it was possible to prevent the liquid crystal alignment failure.

In the region adjacent to the pixel electrode 107a, a second common electrode 103b formed of a transparent metal is formed with the gate insulating layer 102 and the passivation layer 109 therebetween.

That is, in the present invention, the second common electrode 103b forming the electric field together with the pixel electrode 107a is formed of a transparent metal.

In general, in the case of forming an array substrate of a liquid crystal display according to a three-mask process, a pixel electrode electrically connected to the thin film transistor and storage electrodes formed on the common wiring to form a storage capacitance are formed on the lower portion of the common wiring. A large step occurs. In the present invention, the step is minimized by changing the pixel structure.

In particular, the liquid crystal alignment defect frequently occurs in the electrical contact region where a large step is formed, thereby minimizing such defects in the present invention.

FIG. 5 is a cross-sectional view taken along the line II ′ of FIG. 3.

As illustrated in FIG. 5, a cross-sectional view of the thin film transistor region, the contact region of the second storage electrode 107b, the second common electrode 103b, and the first common electrode 103a in FIG. 3 is illustrated.

In the thin film transistor region, contact holes formed on the gate electrode 101, the gate insulating layer 102, the channel layer 104, the ohmic contact layer 106, the source / drain electrodes 105a and 105b and the passivation layer 109 are formed. It is formed according to the 3 mask process.

Here, the drain electrode 105b is electrically connected to the first storage electrode 107 and the contact portion 112 formed on the glass substrate 100.                     

The gate insulating layer 102, the channel layer 104, and the second storage electrode 107b are formed on the first storage electrode to form a storage capacitance together with the first storage electrode 107.

The passivation layer 109 is formed on the second storage electrode 107b, and one side of the second storage electrode 107b is exposed in the contact hole process of the passivation layer 109 to expose the second common electrode 103b. And electrical connection.

The second common electrode 103b is electrically connected to the first common electrode 103a.

That is, since the common signal applied from the common wiring is applied to the second storage electrode 107b via the first common electrode 103a and the second common electrode 103b, the second storage electrode 107b is the same. The storage capacitance is formed together with the first storage electrode 107.

FIG. 6 is a cross-sectional view of the region of KK ′ of FIG. 3, and is illustrated in FIG. 3. The contact region of the second common electrode 103b electrically connected to the common line 103 and branched to the pixel region is illustrated in FIG. 3. This is a cross-sectional view cut.

The common wiring 103 is formed on the glass substrate 100, and a gate insulating film 102 and a protective film 109 are formed on the common wiring 103.

In order to electrically connect with the second common electrode 103b, a part of the common wiring 103 is exposed in the process of forming a contact hole on the passivation layer 109.                     

As described above, the transparent metal is deposited in an area where a part of the common wiring 103 is exposed, and thus the second common electrode 103b is formed in the slit form in the pixel area.

Therefore, in the present invention, even if the array substrate is formed in accordance with the three mask process, there is almost no step difference between the common wiring 103 and the second common electrode 103b, so that alignment failure does not occur when the liquid crystal is aligned by the rubbing cloth. Will not.

Therefore, in the present invention, while forming the array substrate in a three-mask process according to the lift-off process, the liquid crystal rubbing defect is eliminated by minimizing the step difference generated in the contact region.

As described in detail above, the present invention simplifies the manufacturing process by manufacturing the transverse electric field type liquid crystal display device according to a three mask process, while forming a common electrode and a pixel electrode formed in the unit pixel region in a bent structure to improve the viewing angle. It has an improved effect.

In addition, it is possible to minimize the step difference between the contact areas of the wirings and the electrodes, thereby improving the problem of preventing light leakage defects and reducing the contrast ratio.

The present invention is not limited to the above-described embodiments, and various changes can be made by those skilled in the art without departing from the gist of the present invention as claimed in the following claims.

Claims (10)

Depositing and etching a metal film on the transparent insulating substrate to form a gate electrode, a gate wiring, a common wiring, a first common electrode, and a first storage electrode; Sequentially applying and depositing a gate insulating film, a semiconductor film, and a metal film on the insulating substrate on which the gate electrode is formed, and etching the same to form a source / drain electrode, a data line, a second storage electrode, and a channel layer; Applying a protective film on the insulating substrate on which the source / drain electrodes are formed, and then applying a photosensitive film to expose and develop a photoresist pattern to form a contact hole; And Forming a contact hole to expose the drain electrode along the photoresist pattern, and simultaneously etching the passivation layer and the gate insulating layer at a predetermined interval in the pixel region so that the gate insulating layer and the passivation layer are laminated and patterned at the predetermined interval in the pixel region. next, Depositing a transparent metal film on the insulating substrate on which the photosensitive film pattern is formed, and alternately forming a pixel electrode and a second common electrode between the stacked gate insulating film and the protective film according to a lift-off process; And forming a contact portion made of a transparent metal film on the exposed insulating substrate between the first storage electrodes to electrically connect the drain electrode and the first storage electrode. The method of claim 1, The source / drain electrode, the data line, the second storage electrode and the channel layer are formed by a diffraction exposure process. delete delete Board; Data lines, gate lines, and common lines intersected on the substrate to define a unit pixel area; A switching element disposed in an area where the data line and the gate line cross each other; A first common electrode branched from the common wiring and formed in a direction parallel to the data wiring; A pixel electrode and a second common electrode which are alternately disposed on the unit pixel area at predetermined intervals; A first storage electrode connected to the drain electrode of the switching element; And And a second storage electrode overlapping the gate insulating layer and the channel layer on the first storage electrode. The pixel electrode and the second common electrode are formed of a transparent metal, and a gate insulating film and a protective film are stacked and patterned between the pixel electrode and the second common electrode, and the pixel electrode and the second common electrode are stacked gate insulating films. And a protective film formed between the substrate and the passivation layer. The method of claim 5, And the pixel electrode and the second common electrode have a slit structure. delete The method of claim 5, And a contact portion electrically connecting the drain electrode and the first storage electrode of the switching element. The method of claim 5, The second storage electrode is electrically connected to any one of the second common electrode. The method of claim 5, The pixel electrode is electrically connected to the first storage electrode.

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