KR20010066256A - liquid crystal display device and fabrication method thereof - Google Patents

Abstract

The present invention provides a method of manufacturing a liquid crystal display by reducing the number of masks, comprising the steps of: providing a pixel region and a substrate having a switching region defined at one corner of the pixel region; Forming a gate wiring including a gate electrode with a first mask; A gate insulating film, a pure semiconductor layer, and an impurity semiconductor layer are stacked in this order, and the semiconductor layer is patterned with a second mask to provide data auxiliary wiring in an area where a data wiring is to be formed, an active layer on the gate electrode, and the gate wiring Forming at least one short circuit protection portion covering a portion of the gap; Forming a data line covering the source and drain electrodes and the data auxiliary line with a third mask, and a capacitor electrode covering a portion of the gate line other than the short circuit prevention unit; Forming a passivation layer covering the source and drain electrodes and the entire surface of the substrate; Applying a negative photoresist on the passivation layer and etching the passivation layer formed in the pixel region with a mask No. 4; A method of manufacturing an array substrate of a liquid crystal display device, comprising forming a pixel electrode by depositing a transparent conductive electrode on the entire surface of the substrate on which the passivation layer is formed and patterning with a mask No. 4.

Description

Liquid crystal display device and fabrication method thereof

The present invention relates to an image display device, and more particularly, to a manufacturing method of a liquid crystal display (LCD) including a thin film transistor (TFT) and a liquid crystal display device according to the manufacturing method. will be.

In particular, the present invention relates to a method of manufacturing by reducing the number of masks used in manufacturing a liquid crystal display, and a liquid crystal display manufactured by the method.

The driving principle of the liquid crystal display device uses the optical anisotropy and polarization property 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.

Accordingly, when the molecular arrangement direction of the liquid crystal is arbitrarily adjusted, the molecular arrangement of the liquid crystal is changed, and light is refracted in the molecular arrangement direction of the liquid crystal due to optical anisotropy to express image information.

Currently, the active matrix liquid crystal display (AM-LCD) in which the above-described thin film transistor and pixel electrodes connected to the thin film transistor are arranged in a matrix manner has attracted the most attention due to its excellent resolution and ability to implement video.

In general, the structure of a liquid crystal panel, which is a basic component of a liquid crystal display, will be described.

1 is a cross-sectional view showing a cross section of a general liquid crystal panel.

In the liquid crystal panel 20, two substrates 2 and 4 having various kinds of elements are formed to correspond to each other, and the liquid crystal layer 10 is interposed between the two substrates 2 and 4. .

The liquid crystal panel 20 includes an upper substrate 4 having a color filter representing a color and a lower substrate 2 having a switching circuit capable of converting a molecular arrangement direction of the liquid crystal layer 10.

The upper substrate 4 includes a color filter layer 8 for implementing color and a common electrode 12 covering the color filter layer 8. The common electrode 12 serves as one electrode for applying a voltage to the liquid crystal 10. The lower substrate 2 has a thin film transistor S serving as a switching function and a pixel electrode 14 serving as an electrode for receiving a signal from the thin film transistor S and applying a voltage to the liquid crystal 10. It is composed of

The portion where the pixel electrode 14 is formed is called the pixel portion P. FIG.

In order to prevent leakage of the liquid crystal 10 injected between the upper substrate 4 and the lower substrate 2, sealants (sealant) is formed at the edges of the upper substrate 4 and the lower substrate 2. It is sealed with).

Referring to the operation and configuration of the lower substrate 2 in Figure 2 showing a plan view of the lower substrate 2 shown in FIG. 1 as follows.

The pixel electrode 14 is formed on the lower substrate 2, and the data line 24 and the gate line 22 are formed in the vertical and horizontal alignment directions of the pixel electrode 14, respectively.

In the active matrix liquid crystal display device, a thin film transistor S, which is a switching element for applying a voltage to the pixel electrode 14, is formed at one portion of the pixel electrode 14. The thin film transistor S includes a gate electrode 26, source and drain electrodes 28 and 30, and a gate electrode 26 is formed to protrude and extend in a portion of the gate wire 22. The source electrode 28 is connected to the data line 24.

The drain electrode 30 is electrically connected to the pixel electrode 14 through the drain contact hole 30 ′.

In addition, a storage capacitor C _st is formed in a portion of the gate line 22 to store charge together with the pixel electrode 14.

The storage capacitor C _{st is} formed using the gate wiring 22 as one electrode and the capacitor electrode 58 formed on the gate wiring as another electrode.

Referring to the operation of the active matrix liquid crystal display, when a signal is applied to the gate electrode 26 of the switching thin film transistor S, the data signal is applied to the pixel electrode 14 and the signal is applied to the gate electrode 26. If not applied, the data signal is not applied to the pixel electrode 14.

The manufacturing process of the liquid crystal panel constituting the liquid crystal display device is a complex process of several complex steps. In particular, the lower substrate on which the thin film transistor S is formed must go through several mask processes.

The performance of the final product is determined by this complex manufacturing process. Preferably, the simpler the process, the less likely it is that defects will occur. That is, since a number of major elements that determine the performance of the liquid crystal display are formed on the lower substrate, the manufacturing process should be simplified.

In general, the manufacturing process of the lower substrate is often determined by what material is used for each device to be made or designed according to the specification.

For example, in the past, a small liquid crystal display was not a problem, but in the case of a large area liquid crystal display of 12 inches or more, the resistivity value of the material used for the gate wiring is an important factor in determining the superiority of the image quality. Therefore, in the case of a large area liquid crystal display element, it is preferable to use a metal with low resistance, such as aluminum or an aluminum alloy.

Hereinafter, a manufacturing process of a conventional active matrix liquid crystal display device will be described with reference to FIGS. 3A to 3E. 3A to 3E are process diagrams showing a process of a cross section taken along cut line III-III of FIG. 2 for ease of explanation.

In general, the structure of a thin film transistor used in a liquid crystal display is an inverted staggered structure. This is because the structure is simple and the performance is excellent.

In addition, the reverse staggered thin film transistor is divided into a back channel etch type (EB) and an etch stopper type (ES) according to a channel forming method, and a simple back channel etch type structure is applied. The liquid crystal display device manufacturing process will be described.

First, a foreign material or an organic material is removed from the substrate 1, and the metal film is deposited by sputtering after cleaning to improve the adhesion between the metal film of the gate material to be deposited and the glass substrate. .

3A is a step of forming a gate electrode 26 and a gate wiring 22 by patterning the metal film after deposition. The gate electrode 26 material, which is important for the operation of the active matrix liquid crystal display, is mainly composed of aluminum having low resistance to reduce the RC delay, but pure aluminum has low chemical resistance to corrosion and is healed in subsequent high temperature processes. In the case of aluminum wiring, it is used in the form of an alloy or a laminated structure is applied because it causes a wiring defect problem due to the formation of the hi-lock.

Next, referring to FIG. 3B, after the gate electrode 26 and the gate wiring 22 are formed, a gate insulating film 50 is deposited over the upper portion and the entire surface of the exposed substrate 1.

In addition, amorphous silicon (a-Si: H: 52), which is a semiconductor material, and amorphous silicon (n ⁺ a-Si: H: 54) containing impurities are deposited on the gate insulating film 50 in succession.

The amorphous silicon 54 containing the impurity is to reduce the contact resistance between the metal layer to be formed later and the active layer 55.

Thereafter, as shown in FIG. 3C, the metal layer is deposited and patterned to form the source electrode 28 and the drain electrode 30.

In addition, a capacitor electrode 58 is formed on the insulating film 50 on the gate wiring 22 so as to overlap a part of the gate wiring 22. That is, in the third mask process, the source electrode 28, the drain electrode 30, and the capacitor electrode 58 are formed.

The ohmic contact layer existing between the source electrode 28 and the drain electrode 30 is removed using the source and drain electrodes 28 and 30 as a mask. If the ohmic contact layer between the source electrode 28 and the drain electrode 30 is not removed, a serious problem may occur in the electrical characteristics of the thin film transistor S, and a great problem may occur in performance.

Careful attention is required to removing the ohmic contact layer. In actual etching of the ohmic contact layer, since there is no etch selectivity with the active layer formed below, the active layer is overetched by about 50 to 100 nm. The etching uniformity directly affects the characteristics of the thin film transistor S. Crazy

Thereafter, as shown in FIG. 3D, an insulating film is deposited and patterned to form a protective film 56 to protect the active layer 55. The passivation layer 56 may adversely affect the characteristics of the thin film transistor due to the unstable energy state of the active layer 55 and the residual material generated during etching, so that the inorganic silicon nitride layer (SiN _x ) or the silicon oxide layer (SiO ₂ ) or the like may be adversely affected. It is formed of inorganic BCB (Benzocyclobutene).

The passivation layer 56 requires high light transmittance, properties of a moisture resistant and durable material.

A process of forming a contact hole during patterning of the passivation layer 56 is added, and a drain contact hole 30 'and a storage contact hole 58' are formed, respectively.

The drain contact hole 30 'and the storage contact hole 58' are for contact with the pixel electrode.

Thereafter, a transparent conductive material (TCO) is deposited and patterned on the passivation layer 56 to form the pixel electrode 14. ITO (Indium Tin Oxide) is mainly used as the transparent conductive material. The pixel electrode 14 is in contact with the capacitor electrode 58 and is in electrical contact with the drain electrode 30 through the drain contact hole 30 ′.

By the above-described process, the thin film transistor substrate of the liquid crystal display device is completed.

4 is a flowchart illustrating a manufacturing process of FIGS. 3A to 3E.

ST200 uses a glass substrate (1) to prepare a substrate. In addition, the process of cleaning the glass substrate 1 is included. Cleaning is aimed at enhancing the adhesion of the thin film to be deposited and improving the characteristics of the thin film transistor, in addition to the basic concept of removing impurities and particles in the substrate or film surface during the initial process to prevent defects.

ST210 is a step of depositing a metal film, and is formed by depositing aluminum or molybdenum. Then, using a lithography technique, the gate electrode and the storage first electrode are formed to have a tapered shape.

ST220 deposits an insulating film, amorphous silicon, and amorphous silicon containing impurities. The insulating film deposits a silicon nitride film or a silicon oxide film with a thickness of about 3000 Å. After deposition of the insulating film, an amorphous silicon film and an amorphous silicon film containing impurities are successively deposited.

ST230 is a step of depositing and patterning a metal such as chromium or chromium alloy to form a source electrode and a drain electrode.

ST240 is a step of forming a channel by removing the impurity semiconductor layer using the source and drain electrodes formed in ST230 as a mask.

ST250 is a step of forming a protective film for protecting the devices. The protective film is made of a material resistant to moisture or external impact. In the process, a contact hole is formed as a medium connected to each device.

ST260 is a step of forming a pixel electrode by depositing and patterning ITO with a transparent conductive electrode (TCO).

The manufacturing method of the active matrix liquid crystal display described above is a five mask method used basically.

That is, five masks such as a gate pattern, an active pattern, a source and drain electrode pattern, a protective film pattern, and a pixel electrode pattern are used. In other words, conventionally, five types of masks are required in order to manufacture the array substrate of a liquid crystal display device.

Therefore, even if the structure of the array substrate is slightly changed, the five types of masks must be redesigned, which increases the time and cost for designing the masks.

Accordingly, an object of the present invention is to provide a method for reducing the number of masks used in manufacturing a liquid crystal display device and to improve the production yield of a product.

1 is a cross-sectional view showing a cross section corresponding to one pixel portion of a general liquid crystal display device.

2 is a plan view illustrating a plane corresponding to a part of a general liquid crystal display;

3A to 3D are process diagrams showing a cross section process along cut line III-III of FIG. 2;

4 is a flowchart showing a process of a general liquid crystal display.

5 is a plan view illustrating a plane of a liquid crystal display according to an exemplary embodiment of the present invention.

FIG. 6A to FIG. 6D are process diagrams illustrating a fabrication process of a cross section taken along cut line VI-VI of FIG. 5. FIG.

FIG. 7 is a cross-sectional view taken along a cut line VIII-VIII in FIG. 5; FIG.

8 shows another example of the portion F of FIG. 5;

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

100: gate wiring 102: gate electrode

110: data wiring 112: data wiring auxiliary electrode

114: source electrode 116: drain electrode

118: pixel electrode 120: etching prevention unit

122 capacitor electrode 132 gate insulating film

134: active layer 136: protective film

138: negative PR 200: mask for the pixel electrode pattern

In order to achieve the above object, the present invention includes a substrate in which a pixel region and a switching region are defined; Gate and data lines formed in the horizontal and vertical directions of the pixel region; A thin film transistor receiving a signal from the gate and the data line and including a gate, a source, a drain electrode, and an active layer formed in the switching region; A pixel electrode receiving a signal from a drain electrode of the thin film transistor and having a portion overlapped with the gate line and an insulating layer therebetween; At least one etch stopper inserted into a first region of the overlapped portion of the gate line and the pixel electrode; An array substrate of a liquid crystal display device including a capacitor electrode formed in a second region of a portion where the gate line and the pixel electrode overlap each other is provided.

In addition, the present invention includes the steps of: providing a pixel region and a substrate having a switching region defined at one corner of the pixel region; Forming a gate wiring including a gate electrode with a first mask; A gate insulating film, a pure semiconductor layer, and an impurity semiconductor layer are stacked in this order, and the semiconductor layer is patterned with a second mask to provide data auxiliary wiring in an area where a data wiring is to be formed, an active layer on the gate electrode, and the gate wiring Forming at least one short circuit protection portion covering a portion of the gap; Forming a data line covering the source and drain electrodes and the data auxiliary line with a third mask, and a capacitor electrode covering a portion of the gate line exposed by the short circuit prevention unit; Forming a passivation layer covering the source and drain electrodes and the entire surface of the substrate; Applying a negative photoresist on the passivation layer and etching the passivation layer formed in the pixel region with a mask No. 4; And depositing a transparent conductive electrode on the entire surface of the substrate on which the protective film is formed, and patterning the transparent conductive electrode on the front surface of the substrate to form a pixel electrode to partially overlap with the short-circuit prevention portion and the capacitor electrode formed on the front or rear gate wiring. A method of manufacturing an array substrate of a display device is provided.

In particular, the present invention provides a method of manufacturing a liquid crystal display using only four masks that are basically used.

In the present invention, a protective film is formed by using a negative photoresist and a mask for forming a pixel electrode.

The negative PR has a characteristic in which an unexposed portion reacts with the developer and is removed by the developer. Therefore, the metal in the unexposed portion is etched when the metal or the like is patterned.

For reference, positive PR has a property opposite to that of the negative PR, and the metal of the exposed portion is patterned.

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

5 is a plan view illustrating a plane of a liquid crystal display according to an exemplary embodiment of the present invention, in which a gate line 100 is formed in a horizontal direction, and a data line 110 is formed in a vertical direction.

A gate electrode 102 protrudes and is formed in the gate line 100, and a source electrode 114 protrudes and extends in the data line 110 near the gate electrode 100, so that the gate electrode 102 is formed. ) And a predetermined area overlap.

In addition, a drain electrode 116 is formed in a direction corresponding to the source electrode 114 around the gate electrode 102, and the pixel electrode 118 contacting the drain electrode 116 is connected to the gate wiring ( 100) and a predetermined interview overlap.

The data auxiliary line 112 is formed under the data line 110, and the data auxiliary line 112 is made of pure amorphous silicon.

In addition, at least one short circuit prevention part 120 made of the same material as the data auxiliary line 112 is formed at a portion where the gate wiring 100 and the pixel electrode 118 overlap each other, and the short circuit prevention part 120 is formed. Capacitor electrodes 122 of the same material as the source and drain electrodes 114 and 116 are overlapped with the short-circuit prevention part 120 in a portion other than).

The function of the short circuit prevention unit 120 will be described later.

In addition, a protective film 130 is formed on the entire substrate of portions other than the pixel electrode 118. The passivation layer 130 is formed by a photolithography process using negative PR, which will be described later.

6A to 6D are process diagrams illustrating a manufacturing process of a cross section taken along the cutting line VI-VI of FIG. 5. In the manufacturing process of the liquid crystal display device according to the present invention, only four types of masks are used to manufacture the liquid crystal display device. Give a way.

First, FIG. 6A illustrates a step of forming the gate electrode 102 and the gate wiring 100 on the substrate 1.

Substantially, in the drawing shown in FIG. 6A, the gate line 100 and the gate electrode 102 are formed independently of each other. That is, they are electrically independent. However, the gate wiring 100 may operate as one electrode of a storage capacitor (not shown) in a later process.

FIG. 6B illustrates forming an active layer 134 and a short circuit prevention unit 120 by depositing and patterning a gate insulating layer 132 and a semiconductor layer on the gate electrode and the wirings 102 and 100, and the active layer 134. The steps of forming the source and drain electrodes 114 and 116 and the channel CH in contact with each other are shown.

The active layer 134 is a stack structure of pure amorphous silicon 134a and impurity amorphous silicon 134b, and the channel CH is formed using the source and drain electrodes 114 and 116 as masks.

In addition, the etch stop unit 120 is patterned with the same material as the pure amorphous silicon 134a and formed to overlap a predetermined area with the gate line 100.

Here, the etch stop unit 120 may cope with the capacitor electrode 122. That is, when the capacitor electrode 122 is formed to overlap a predetermined area with a boundary portion of the gate line 100 at a portion where the pixel electrode 118 and the gate line 100 overlap each other, the etch stop 120 At the same time, the capacity of the storage capacitor increases as the area of the storage capacitor increases while performing a function.

FIG. 6C illustrates a negative photoresist (PR) 138 in order on the passivation layer 136 and the passivation layer 136 over the source and drain electrodes 114 and 116, the etch stop 120, and the entire surface of the substrate. , Which shows the step of patterning.

Although the negative PR 138 has been described above, it will be described again, so that the PR of the exposed portion remains during the development process and finally, the unexposed portion is etched. The negative PR 138 and the pixel electrode pattern mask ( 200, the passivation layer 136 is patterned.

Accordingly, the patterned passivation layer 136 remains in the entire region except for the portion where the pixel electrode (not shown) is finally formed.

In this case, the etch stop unit 120 serves to prevent etching of the gate insulating layer 132 formed under the protective layer 136. The protective layer 136 and the gate insulating layer 132 have a functional difference, but are formed using the same material. Therefore, when the protection layer 136 is etched, the gate insulating layer 132 may be over-etched because there is no etching selectivity with the gate insulating layer 132.

If the gate insulating layer 132 formed on the gate wiring 100 is overetched, an electrical short with the pixel electrode to be generated in a later process may occur, which may result in the formation of a storage capacitor. . In order to prevent this, the etching prevention unit 120 is formed. As the passivation layer 136 to the gate insulating layer 132, a silicon nitride layer (SiN _x ), a silicon oxide layer (SiO ₂ ), or the like is used.

6D is a view illustrating a step of forming the pixel electrode 118.

The pixel electrode 118 is formed using a pixel electrode pattern mask and a positive PR used in the patterning process of the passivation layer 136 of FIG. 6C and the entire surface of the patterned passivation layer 136 and the substrate. do.

Accordingly, the pixel electrode 118 is formed in a region other than the patterned passivation layer 136.

In addition, the pixel electrode 118 is in contact with the drain electrode 116. In the related art, the drain contact hole is used to contact the pixel electrode and the drain electrode, but in the present invention, the drain electrode 116 and the pixel electrode are used. 118 is in direct contact with the drain contact hole. That is, the process of the drain contact hole is removed.

Therefore, the manufacturing process of the liquid crystal display device according to the present invention can be manufactured using only four masks, and since the drain contact hole process is removed, the manufacturing process is simplified.

In addition, since the contact between the pixel electrode 118 and the drain electrode 116 is a direct contact rather than a contact through the drain contact hole, the contact resistance is reduced.

In the pixel electrode 118, indium tin oxide (ITO), indium zinc oxide (IZO), or the like is used.

FIG. 7 is a cross-sectional view taken along the line VII-VII of FIG. 5, and illustrates a relationship between the capacitor electrode 122 and the etch stop 120.

The etch stop 120 prevents the gate insulating film 132 formed on the gate line 100 from being overetched when the passivation layer 136 is patterned, and overlaps the capacitor electrode 122 with a predetermined area.

In addition, the capacitor electrode 122 directly contacts the pixel electrode 118.

8 is an enlarged view of a portion F of FIG. 5 and illustrates another example according to the present invention.

That is, an etching prevention part (not shown) may be removed between the gate line 122 and the portion where the pixel electrode 118 overlaps, and the capacitor electrode 122 may be formed instead. If the capacitor electrode 122 is formed in the region where the etch stop is to be formed as described above, it is obvious that the capacitance of the storage capacitor is further increased.

That is, the drawing illustrated in FIG. 8 will be an example in which the etch stop 120 is replaced with the capacitor electrode 122.

As described above, the manufacturing method of the liquid crystal display according to the present invention has advantages in that manufacturing cost can be reduced because only four masks can be manufactured.

In addition, since the liquid crystal display device can be manufactured using only four masks, there is an advantage in that the mask can be quickly dealt with.

When the liquid crystal display is manufactured by the embodiments of the present invention described above has the following characteristics.

First, when the liquid crystal display device is manufactured by the method of manufacturing the liquid crystal display device according to the embodiments of the present invention, since only four masks can be manufactured, manufacturing cost is reduced.

Second, since the thin film transistor substrate can be composed of four masks, there is an advantage that it can cope quickly when designing the mask.

Third, when the drain electrode and the pixel electrode are in direct contact with each other instead of the contact hole, the contact resistance is reduced.

Fourth, if the etching prevention portion for preventing over-etching of the gate insulating film formed on the gate wiring is replaced by the capacitor electrode, the capacity of the storage capacitor is increased.

Claims (7)

A substrate in which a pixel region and a switching region are defined; Gate and data lines formed in horizontal and vertical directions of the pixel region; A thin film transistor receiving a signal from the gate and the data line and including a gate, a source, a drain electrode, and an active layer formed in the switching region; A pixel electrode receiving a signal from a drain electrode of the thin film transistor and having a portion overlapped with the gate line and an insulating layer therebetween; At least one etch stopper inserted into a first region of the overlapped portion of the gate line and the pixel electrode; Capacitor electrode formed in the second region of the portion where the gate wiring and the pixel electrode overlap Array substrate of a liquid crystal display comprising a. The method according to claim 1, And the etching prevention portion is made of the same material as the active layer. The method according to claim 1, And the capacitor electrode is formed of the same material as the source and drain electrodes. The method according to claim 1, The pixel electrode is an indium tin oxide (ITO), indium zinc oxide (IZO) array substrate of a liquid crystal display device. Providing a pixel region and a substrate in which a switching region is defined at one corner of the pixel region; Forming a gate wiring including a gate electrode with a first mask; A gate insulating film, a pure semiconductor layer, and an impurity semiconductor layer are stacked in this order, and the semiconductor layer is patterned with a second mask to provide data auxiliary wiring in an area where a data wiring is to be formed, an active layer on the gate electrode, and the gate wiring Forming at least one short circuit protection portion covering a portion of the gap; Forming a data line covering the source and drain electrodes and the data auxiliary line with a third mask, and a capacitor electrode covering a portion of the gate line exposed by the short circuit prevention unit; Forming a passivation layer covering the source and drain electrodes and the entire surface of the substrate; Applying a negative photoresist on the passivation layer and etching the passivation layer formed in the pixel region with a mask No. 4; Depositing a transparent conductive electrode on the entire surface of the substrate on which the passivation layer is formed, and patterning it with a mask No. 4 to form a pixel electrode to partially overlap with the short circuit prevention part and the capacitor electrode formed on the front or rear gate wiring; Array substrate manufacturing method of the liquid crystal display device comprising a. The method according to claim 5, And forming the channel by removing the impurity amorphous silicon using the source and drain electrodes as masks before forming the passivation layer. The method according to claim 5, The pixel electrode is an indium tin oxide (ITO), indium zinc oxide (IZO) array substrate manufacturing method of a liquid crystal display device.