KR101258084B1 - Liquid crystal display device and fabrication method thereof - Google Patents

Abstract

According to an aspect of the present invention, there is provided a method of fabricating a liquid crystal display device, the method including: providing a substrate in which a pixel region and a peripheral region are defined and a dummy layer having a predetermined height is formed in the peripheral region; Preparing a first substrate by forming a thin film transistor on the pixel region of the substrate; Preparing a second substrate; And forming a liquid crystal layer between the first substrate and the second substrate.

Liquid crystal amount, dummy layer, patterned glass

Description

Liquid crystal display device and its manufacturing method {LIQUID CRYSTAL DISPLAY DEVICE AND FABRICATION METHOD THEREOF}

1 is a cross-sectional view of a conventional liquid crystal display device.

2 is a flowchart illustrating a manufacturing method of a conventional liquid crystal display device.

3 is a plan view illustrating some pixels of a substrate on which a thin film transistor is formed;

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

5 is a cross-sectional view showing some elements of a thin film transistor according to the present invention.

6 is a cross-sectional view showing a substrate on which a dummy layer is formed of an insulating layer according to the present invention.

7 is a cross-sectional view showing a substrate in which a dummy layer is formed on the substrate itself according to the present invention.

8 is a cross-sectional view showing an embodiment of a liquid crystal display device in which a dummy layer according to the present invention is formed on a second substrate.

Description of the main parts of the drawing

T: thin film transistor 115: data line

130: dummy layer 140: black matrix

Recently, the importance of the display device for displaying various information is increasing with the rapid development of the information and communication field, and one of the existing display devices (Cathode Ray Tube) has a certain limit to meet the latest trend of light weight and thinning. Could not. As a flat panel display, a liquid crystal display (LCD), a plasma display panel (PDP), and an electroluminescence display (ELD) have been developed to meet expectations, and research and development are actively conducted. It is becoming.

Among the display devices, liquid crystal display devices are displays having advantages such as light weight, thinness, and low power, and are widely used not only for display devices such as notebook computers, but also for desktop computers and large TVs. have. In recent years, liquid crystal display devices have become more and more large and thin, and the manufacturing process is being automated.

1 is a cross-sectional view schematically showing a cross section of a general liquid crystal display device. As shown in the figure, the liquid crystal display device 1 includes a liquid crystal layer 7 formed between the first substrate 5 and the second substrate 3 and between the first substrate 5 and the second substrate 3. It consists of. The first substrate 5 is a substrate on which a thin film transistor (TFT), which is a driving element, is formed. Although not shown in the drawing, a plurality of pixels are formed, and each pixel is formed of a thin film transistor. The upper substrate 3 is a color filter substrate, and a color filter layer for realizing color is formed. In addition, a pixel electrode and a common electrode are formed on the first substrate 5 and the second substrate 3, respectively, and an alignment film for aligning liquid crystal molecules of the liquid crystal layer 7 is coated.

The first substrate 5 and the second substrate 3 are bonded by a sealing material 9, and a liquid crystal layer 7 is formed therebetween to drive the first substrate 5. The device displays the information by controlling the amount of light passing through the liquid crystal layer by driving the liquid crystal molecules.

The manufacturing process of the liquid crystal display device is largely a driving element thin film transistor substrate process for forming a driving element on the first substrate 5 and a color filter substrate process and a cell process for forming a color filter on the second substrate 3. The process of such a liquid crystal display device will be described with reference to FIG. 2 as follows.

First, a plurality of gate lines and data lines are formed on the first substrate 5 by a driving element thin film transistor process to define pixel regions, and the gate lines are formed in each of the pixel regions. And a thin film transistor which is a driving element connected to the data line (S101). In addition, the driving device is connected to the thin film transistor through the thin film transistor process to form a pixel electrode for driving the liquid crystal layer as a signal is applied through the thin film transistor.

In addition, the second substrate 3 is formed with a color filter layer and a common electrode of R, G, B to implement color by a color filter process (S104). Subsequently, an alignment film is applied to the second substrate 3 and the first substrate 5, respectively, and then alignment control force or surface is applied to the liquid crystal molecules of the liquid crystal layer formed between the second substrate 3 and the first substrate 5. In order to provide a fixing force (ie, a pretilt angel and an orientation direction), the alignment layer is rubbed (S102 and S105). Subsequently, the first substrate 5 is spread with a spacer for keeping the cell gap constant and a sealing material is applied to the outer portion of the second substrate 3, and then the first substrate 5 is applied. And the second substrate 3 by applying pressure (S103, S106, S107). On the other hand, the first substrate 5 and the second substrate 3 is made of a large area of the substrate. In other words, a plurality of panel regions are formed on a large-area substrate, and a TFT and a color filter layer serving as driving elements are formed in each of the panel regions. (S108). Thereafter, liquid crystal is injected into the individual liquid crystal panel processed as described above through the liquid crystal inlet, and the liquid crystal inlet is encapsulated to form a liquid crystal layer, and then the liquid crystal display is manufactured by inspecting each liquid crystal panel (S109 and S110). .

Therefore, the liquid crystal is injected between the first substrate and the second substrate. The liquid crystal must be filled by the cell gap between the first substrate and the second substrate.

3 and 4 are plan views showing some pixels for the liquid crystal display, and cross-sectional views taken along the line II ′ of FIG. 3.

As shown, the gate line 13 and the data line 15 are formed on the first substrate 10 on which the thin film transistor is formed to cross each other in a matrix, and the gate line 13 and the data line ( The thin film transistor T is formed at the intersection point of 15). The thin film transistor T includes a gate electrode 25, an active layer 19, a source electrode 21, and a drain electrode 23. The pixel electrode 17 is formed on the entire surface of the area defined by the gate line 13 and the data line 15 intersecting, which is called a pixel area. The pixel electrode 17 is in side contact with the drain electrode 23.

In this configuration, the color filter 44 is formed in the pixel area of the second substrate 12 as an area for implementing an image. Since the portion except the pixel region, that is, the region in which the data line 15 and the gate line 13 are formed, is a region where light leakage occurs, the black matrix 40 covers the portion. Done. In addition, a black matrix 40 is formed on the thin film transistor T to prevent light leakage.

The liquid crystal 50 is filled between the first substrate 11 and the second substrate 12, and the cell gap corresponds to H ₀ .

In this case, the region where the black matrix 40 is formed is not a portion in which an image is expressed, and thus is not related to the alignment and the amount of liquid crystal. However, when a substrate is prepared by forming a device, a color filter, or the like, and the two substrates are bonded to each other, the liquid crystal should be filled as much as the cell gap between the two substrates. Since liquid crystals are expensive, an increase in the amount of liquid crystals leads to an increase in product cost, so it is desirable to reduce the liquid crystal amount margin. Therefore, the pixel area affected by the alignment or amount of the liquid crystal should be finely controlled in the liquid crystal amount and the cell gap, but the area covered by the black matrix need not be so, so a method for reducing the liquid crystal amount has been required.

In order to solve the above problems, the present invention manufactures a liquid crystal display using a patterned glass in which a dummy layer having a predetermined height is formed in a peripheral area where a black matrix is not formed, thereby forming a cell gap in the peripheral area. It is an object of the present invention to provide a liquid crystal display device and a method of manufacturing the same by reducing the amount of liquid crystal used between two substrates.

A liquid crystal display device according to the present invention includes a first substrate having a pixel region and a peripheral region defined therein, a dummy layer having a predetermined height in the peripheral region, a plurality of gate lines, data lines, and thin film transistors formed on the dummy layer; ; A second substrate facing the first substrate; And a liquid crystal layer filled between the first substrate and the second substrate. The method for manufacturing the liquid crystal display device includes a pixel region and a peripheral region, and a dummy layer having a predetermined height in the peripheral region. Providing a formed substrate; Preparing a first substrate by forming a thin film transistor on the pixel region of the substrate; Preparing a second substrate; And forming a liquid crystal layer between the first substrate and the second substrate.

Forming the dummy layer to provide a substrate includes depositing an insulating film on the substrate and patterning the insulating film.

In addition, another step of forming the dummy layer includes a step of forming a patterned substrate.

The dummy layer is formed on a first substrate and / or a second substrate.

In the liquid crystal display device, an area where a pixel electrode is formed is an area where an image is implemented according to an alignment of the liquid crystal, and a part where an image is not implemented is an area where a black matrix is formed. In the present invention, the pixel region and the peripheral region are defined and described below. The pixel region is a region in which the pixel electrode is formed, and is defined as an region in which an image is implemented according to the alignment of liquid crystals. It is defined as an area where black matrices including lines and data lines are formed and thin film transistors are formed.

Therefore, the present invention is characterized in that by forming a dummy layer having a constant height in the peripheral area, the step height of the peripheral area is increased, and as a result, the cell gap of the peripheral area is reduced and the amount of liquid crystal can be reduced.

The present invention is characterized in that a dummy layer is formed in the peripheral region except the pixel region as a method for reducing the liquid crystal amount margin. In other words, it is possible to reduce the cell gap in the peripheral region and to reduce the amount of liquid crystal charged in the peripheral region. Therefore, in the present invention, the dummy layer refers to a pattern formed at a predetermined height to reduce the amount of liquid crystal. Liquid crystal itself is an expensive material, and in order to make a liquid crystal display device, a liquid crystal must be injected into a very narrow gap between two substrates, but it takes a long time when the liquid crystal is injected. Therefore, if the cell gap in the peripheral area is reduced and the amount of liquid crystal used is reduced, the unit cost decreases as well as the liquid crystal injection time.

Since the gate line, the data line and the thin film transistor element are formed on the dummy layer, the upper portion is preferably formed flat. Therefore, it is preferable to deposit the pattern on the entire substrate. However, other methods may be possible if the patterned dummy layer can be formed in a flat manner. The substrate in which the dummy layer is patterned in this manner is called patterned glass.

The dummy layer is formed only in the peripheral area. The image portion of the liquid crystal display device varies depending on the orientation of the liquid crystal and the amount of liquid crystal. However, when the dummy layer as described above is formed in the image region, the portion where the dummy layer exists is smaller than the others, and eventually the amount of charged liquid crystal decreases, so that the amount of light or luminance is changed, so that the image to be realized is different. do. In addition, when the step height of the dummy layer is large, there is a fear of light leakage. However, in the case where the dummy layer is formed only in the peripheral region, even if the liquid crystal has an abnormal orientation, it is not a problem because it is covered by the black matrix.

The liquid crystal display device using the dummy layer will be described with reference to the accompanying drawings.

5 is a cross-sectional view showing some elements of a thin film transistor according to the present invention. The first substrate 110 on which the thin film transistor T is formed may correspond to a portion where the gate line, the data line 115, and the thin film transistor T are formed when the second substrate 112 is bonded to the second substrate 112. The black matrix 140 is formed on the second substrate 112 to form a peripheral region. As shown, between the first substrate 110 and the second substrate 112 in the portion where the thin film transistor T is formed, between the data line 115 and the second substrate 112 and not shown, the gate line (not shown). The dummy layer 130 stacked between the second substrate 112 and the second substrate 112 and forming a step is formed. Where the dummy layer is formed is a place where all the black matrix is to be formed, the dummy layer 130 can be formed at an appropriate height according to the needs, such as the type or use of the liquid crystal display device. At this time, considering the thin film transistor (T) and other components, the dummy layer preferably has a height of about 5000Å.

In the present invention, the cell gap of the pixel area of the first substrate 110 on which the dummy layer 130 is formed is reduced than when there is no dummy layer. Referring to FIG. 5, when the height of the dummy layer 130 is h, it is reduced by h than the cell gap H ₀ (see FIG. 4) when the dummy layer 130 is not present. Therefore, as the cell gap is reduced in the vicinity of the peripheral region, there is an advantage that fewer liquid crystals may be injected.

In order to manufacture the liquid crystal display device according to the embodiment as shown in FIG. 5, the method of forming the dummy layer is as follows.

Although not shown in the drawing, first, a first substrate (not shown; see 110 of FIG. 5) used in the liquid crystal display device is prepared. Various substrates may be used for the liquid crystal display device, but the substrate is preferable. An insulating layer for forming a dummy layer is deposited on the first substrate 110 at a predetermined height. The insulating film may be deposited using a material made of silicon nitride (SiNx), silicon oxide (SiOx), or the like. The height may vary depending on the liquid crystal display and may also vary depending on the overall cell gap. However, compared with the structure formed in another board | substrate, 5000 kPa is preferable. It is then patterned such that the insulating layer remains only in the peripheral region.

6 is a cross-sectional view illustrating a substrate on which a dummy layer is formed as an insulating layer. As shown, an insulating layer 211 remains in a portion of the substrate 210, that is, the peripheral region, to form a dummy layer. 5 illustrates that a dummy layer is formed by the above-described method.

Another way to form the dummy layer is to form a dummy layer on the substrate itself. In the case of the substrate, the pattern may be formed by etching the substrate, not by depositing an insulator or the like.
7 is a cross-sectional view illustrating a substrate on which the dummy layer 311 is formed on the substrate 310 itself. As shown, a dummy layer 311 is formed on a portion of the substrate, that is, the substrate 310 corresponding to the peripheral region.

8 is a cross-sectional view illustrating a liquid crystal display device in which a dummy layer 430 is formed on a second substrate 412.

As illustrated, a thin film transistor T is formed on the first substrate 410, and a color filter 444 and a black matrix 440 are formed on the second substrate 412 opposite to the thin film transistor T. However, the height of the peripheral region is increased by forming the dummy layer 430 at the position where the black matrix 440 is to be formed on the second substrate 412, that is, the peripheral region. Even in this case, the cell gap is reduced, and it can be seen from the drawing that the distance between the thin film transistor T and the second substrate 412 of the first substrate 410 is reduced by the height of the dummy layer 430.

As in the above-described two embodiments, the dummy layer may be formed of any substrate as long as it is a region where the black matrix is to be formed, that is, a peripheral region. It may also be formed on the first substrate and the second substrate at the same time. As long as it does not affect the image of the pixel region, it can be formed on any substrate to reduce the amount of liquid crystal, and the height thereof can be appropriately adjusted.

A method of manufacturing a thin film transistor including a dummy layer as described above is as follows. After forming the substrate on which the thin film transistor is formed, the substrate facing the substrate is bonded.

Although not shown in the drawing, a dummy layer is formed in a peripheral region by first preparing a substrate and then depositing and patterning an insulating film on the substrate. The dummy layer should then be formed in the region corresponding to the position of the black matrix. Alternatively, the dummy layer may be formed by etching the substrate itself. Subsequently, a gate line in one direction and a gate electrode extending from the gate line are formed on the substrate. Then, a gate insulating film, an amorphous silicon layer, and an amorphous silicon layer doped with impurities are sequentially deposited, and a metal layer is deposited by a method such as sputtering. Then, the metal layer and the impurity amorphous silicon layer are patterned by photolithography or the like to form a data line, a source Drain electrodes and impurity semiconductor layers are formed, respectively. The amorphous silicon layer may be crystallized by a solidification crystallization method or excimer laser annealing (ELA) to form a semiconductor layer.

Next, a protective layer is deposited using a silicon nitride film or a silicon oxide film and then patterned together with an amorphous silicon layer to form a protective layer and a semiconductor layer. At this time, the data line (not shown, 415 of FIG. 8), which is not covered by the protective layer when the protective layer is patterned, is also etched. In this case, the film thicknesses of the portions corresponding to the data lines and the pixel regions are different. Therefore, the gate insulating film is etched in the portion where the metal layer is not left, such as the pixel region.

Subsequently, a transparent conductive material such as indium tin oxide (ITO) is deposited and patterned to form a pixel electrode. The pixel electrode (not shown, see 417 of FIG. 8) partially overlaps the drain electrode and contacts the side of the drain electrode. .

The thin film transistor substrate may be formed in the same manner as described above. When using the substrate on which the thin film transistor is formed as the first substrate, preparing the second substrate includes forming a color filter on the substrate. In this case, a color filter layer is formed on the second substrate using pigments such as red (R), green (G), and black (B) in the pixel region, and a black matrix is formed in the peripheral region. When the first substrate and the second substrate are prepared, the liquid crystal display device is manufactured by bonding the two substrates and injecting the liquid crystal. In this case, the patterned glass may be used for any of the two substrates. That is, the dummy pattern may be formed on the first substrate and / or the second substrate. A dummy layer may be formed on one substrate or a dummy layer may be formed on both peripheral regions of the two substrates, and the height of the dummy layer may be adjusted within a range that does not affect the image quality of the liquid crystal display. .

Alternatively, a liquid crystal display device may be manufactured. The present invention may be implemented in a liquid crystal display device having a color filter on transistor (COT) structure in which a color filter is provided on a substrate on which a thin film transistor is formed. That is, the thin film transistor is formed on the substrate on which the dummy layer is formed by using the patterned glass, and the color filter layer is formed on the substrate on which the thin film transistor is formed. In this way, a liquid crystal display device can be manufactured by preparing a first substrate, preparing a second substrate facing the first substrate, and bonding the two substrates together. Of course, even in this case, it is possible to use a patterned glass in which a dummy layer is formed on both substrates.
Although the configuration and implementation of the present invention have been described in detail above, various modifications may be made without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the embodiments, but should be determined not only by the claims mentioned but also by the equivalents of these claims.

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According to the present invention, a cell gap of a peripheral area can be reduced by forming a liquid crystal display by forming a dummy layer having a predetermined height in a peripheral area where a black matrix is not formed. By reducing the cell gap of the peripheral region that does not directly affect the image, it is possible to reduce the amount of liquid crystal injected between the two substrates. When the amount of liquid crystal used can be reduced, the injection time of the liquid crystal is also reduced, thereby increasing the speed of the process, thereby increasing the process efficiency, and providing a liquid crystal display device having reduced cost.

Claims (9)

A first substrate on which pixel regions and peripheral regions are defined; A dummy layer formed in a peripheral region of the first substrate; A plurality of gate lines, data lines, and thin film transistors formed on the dummy layer of the first substrate; A pixel electrode formed in the pixel region of the first substrate and electrically connected to the thin film transistor; A second substrate disposed to face the first substrate and having a black matrix formed at a position facing the peripheral region of the first substrate; And And a liquid crystal layer filled between the first substrate and the second substrate. delete The method of claim 1, And the second substrate includes a color filter layer in a pixel area. Providing a first substrate and a second substrate having pixel regions and peripheral regions defined therein; Forming a dummy layer having a predetermined height in a peripheral region of the first substrate; Forming a thin film transistor on the dummy layer of the first substrate; Forming a pixel electrode electrically connected to the thin film transistor in the pixel region of the first substrate; Forming a black matrix in a peripheral region of the second substrate; Forming a color filter layer in the pixel region of the second substrate; Bonding the first substrate and the second substrate to each other; And Forming a liquid crystal layer between the first substrate and the second substrate. 5. The method of claim 4, Forming a dummy layer in a peripheral region of the first substrate includes depositing an insulating film on the first substrate and patterning the insulating layer to form a dummy layer having a predetermined height in the peripheral region. Liquid crystal display device manufacturing method. 5. The method of claim 4, Forming a dummy layer in the peripheral region of the first substrate, patterning the first substrate comprises forming a dummy layer having a predetermined height in the peripheral region. 5. The method of claim 4, Forming a thin film transistor on the dummy layer of the first substrate, Forming a gate line and a gate electrode on the patterned first substrate; Forming a gate insulating film on an entire surface of the first substrate including the gate electrode; And And forming a data line, a semiconductor layer, and a source / drain electrode defining the pixel region by crossing the gate line perpendicularly to the gate line, and exposing the gate insulating layer formed in each pixel region. Display device manufacturing method. The liquid crystal display device of claim 1, wherein a dummy layer is formed between the second substrate and the black matrix. The method of claim 4, further comprising forming a dummy layer between the second substrate and the black matrix.

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