KR101023718B1 - Liquid Crystal Display Device and method for fabricating the same - Google Patents

Abstract

In order to solve the misalignment problem of the upper and lower substrates, and to provide a liquid crystal display device and a manufacturing method thereof suitable for securing the aperture ratio, to achieve the above object, the liquid crystal display device is a pixel area of the first substrate A black matrix layer formed on an area except for; A first interlayer insulating film formed on the first substrate including the black matrix layer; Gate lines and data lines formed vertically and horizontally on the first interlayer insulating film to define the pixel areas; A thin film transistor formed of a gate electrode, a source electrode, and a drain electrode at an intersection of the gate line and the data line; A second interlayer insulating film having a contact hole on the drain electrode and formed on the first substrate; A pixel electrode formed on the pixel region to contact the drain electrode through the contact hole; A common electrode facing the first substrate at a predetermined interval and on a front surface thereof; The back of the first substrate, including a R, G, B light source that is sequentially turned on at a predetermined time interval for one frame, the backlight for sequentially supplying R, G, B light to the first substrate side It characterized in that it comprises a second substrate provided with. The gate line, the data line, and the thin film transistor are formed on the black matrix layer.

Black matrix layer, misalignment, aperture ratio

Description

Liquid Crystal Display Device and method for fabricating the same

1 is a schematic cross-sectional view of a general liquid crystal display device

2 is a schematic cross-sectional view of a general time division type liquid crystal display device.

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

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

5A through 5D are cross-sectional views illustrating a method of manufacturing a liquid crystal display device according to an exemplary embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

60: lower substrate 61: black matrix layer

62: first interlayer insulating film 51: gate line

51a: gate electrode 52: gate insulating film

53 active layer 53a ohmic contact layer

54: data line 54a: source electrode

54b: drain electrode 54c: storage lower electrode

55 second interlayer insulating film 56 contact hole

57: pixel electrode 57a: storage upper electrode                 

58: first alignment layer 70: upper substrate

71: common electrode 72: second alignment layer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device (LCD), and more particularly, to a field-sequential color (FSC) liquid crystal display device and a manufacturing method thereof.

CRT (Cathode Ray Tube), one of the commonly used display devices, is mainly used for monitors such as TVs, measuring devices, and information terminal devices.However, due to the weight and size of the CRT itself, Could not respond actively to demands.

Therefore, in the trend of miniaturization and weight reduction of various electronic products, CRT has a certain limit in weight and size, and is expected to replace the liquid crystal display (LCD) and gas using an electro-optic effect. Plasma display panels (PDPs) using discharges and EL display devices (ELDs) using electroluminescent effects have been studied. Among them, researches on liquid crystal displays have been actively conducted.

In order to replace the CRT, liquid crystal display devices having advantages such as small size, light weight, and low power consumption have been actively developed. Recently, the liquid crystal display device has been developed enough to perform a role as a flat panel display device. In addition, the demand for the liquid crystal display device is continuously increasing as it is used for a monitor and a large information display device of a desktop computer.

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, active matrix LCDs (AM-LCDs) in which a thin film transistor, which is a switching element, and pixel electrodes connected to the thin film transistor are arranged in a matrix manner, are attracting the most attention due to their excellent resolution and ability to implement video.

Hereinafter, a general liquid crystal display device implementing a screen based on the driving principle will be described.

1 is a schematic cross-sectional view of a general liquid crystal display.

As shown in FIG. 1, a general liquid crystal display device includes a transparent first and second glass substrates 1 and 10 bonded to each other with a predetermined space therebetween, and between the first, second and glass substrates 1 and 10. It consists of a liquid crystal panel composed of a filled liquid crystal layer 15 and a backlight 16 positioned on the rear surface of the first glass substrate 1 to supply light to the liquid crystal panel.

Here, the first glass substrate 1, which is a TFT array substrate, includes a plurality of gate lines (not shown) arranged at one direction at regular intervals and a plurality of gate lines arranged at regular intervals in a direction perpendicular to the respective gate lines. A data line (not shown), a plurality of pixel electrodes 2 formed in a matrix form in each pixel region defined by the intersection of the gate lines and the data lines, and the data lines are switched by signals of the gate lines. A plurality of thin film transistors (T) 3 for transmitting a signal of to the pixel electrodes is formed.

On the second glass substrate 10, which is a color filter substrate, a black matrix layer 11 for blocking light except for the pixel region, R (Red) for transmitting only light of a specific wavelength band and absorbing the remaining light, A color filter layer 12 composed of G (Green) and B (Blue) cells and a common electrode 14 for realizing an image are formed.

Reference numeral 13 is an overcoat layer.

The first and second glass substrates 1 and 10 are bonded to each other by a seal material having a predetermined space by a spacer and having a liquid crystal injection hole, so that the liquid crystal is injected between the two substrates.

1 shows only one pixel area on the first and second glass substrates 1 and 10 for convenience.

However, the general liquid crystal display device having such a structure has the following problems.

First, since the light transmittance of the color filter is 33% or less at a maximum, the loss of light reaching the color filter is large, so that the backlight needs to be brightened to increase the brightness, thereby increasing the power consumption.                         

Second, such a color filter is very expensive compared to other materials of the liquid crystal display device, thus increasing the manufacturing cost of the liquid crystal display device.

In order to solve the problem of the liquid crystal display device, a proposed time-division liquid crystal display device capable of realizing full-color without a color filter is proposed.

In general, a backlight of a liquid crystal display device supplies a white light to a liquid crystal panel while it is always turned on, but a time division type liquid crystal display device sequentially fixes the R, G, and B light sources of R, G, and B backlight units for one frame. It is a method of displaying color image by lighting at time interval.

This time-division method was introduced in about 1960, but it was difficult to realize because the technology for a liquid crystal mode having a high response speed and a light source corresponding to the response speed of the liquid crystal must be followed.

In recent years, however, due to the remarkable development of liquid crystal display technology, Ferroelectric Liquid Crystal (FLC), Optical Compensated Bend (OCB), or Twisted Nematic (TN) liquid crystal mode, which has high-speed response characteristics, and R which enables high-speed lighting A time division type liquid crystal display using a G, B backlight has been proposed.

In particular, the OCB mode is mainly used as the liquid crystal mode for the time division type liquid crystal display device. The OCB cell is subjected to a rubbing treatment in the same direction on opposite sides of the upper and lower substrates, and then a constant voltage is applied to the band. By forming a (bend) structure, the liquid crystal molecules move rapidly when voltage is applied, and the time taken for the liquid crystal to be rearranged, that is, the response time is very fast within approximately 5 msec. Therefore, the liquid crystal cell of the OCB mode is very suitable for a time division type liquid crystal display device because it has almost no afterimage on the screen due to its fast response characteristic.

2 is a schematic cross-sectional view of a general time division type liquid crystal display device.

As shown in FIG. 2, a general time division type liquid crystal display device includes an upper substrate 20 and a lower substrate 25 as an array substrate, and a liquid crystal layer 28 filled between upper and lower substrates 20 and 25. And an R, G, and B three-color backlight 29 for supplying light to the liquid crystal panel including the upper and lower substrates 20 and 25 and the liquid crystal layer 28.

On the surface facing the liquid crystal layer 28 of the upper and lower substrates 20 and 25, the common electrode 22 and the pixel electrode 26 are formed to serve as electrodes for applying a voltage to the liquid crystal layer 28. Formed.

A black matrix 21 is formed between the upper substrate 20 and the common electrode 22 to block light in a region other than the pixel electrode 26 of the lower substrate 25.

On the lower substrate 25, a thin film transistor T 27, which is a switching element electrically connected to the pixel electrode 26, is formed at a position corresponding to the black matrix 21 of the upper substrate 20.

The thin film transistor (T) 27 is composed of a gate electrode, a source, and a drain electrode, not shown.

Reference numeral '19' is an overcoat layer.

2 illustrates only one pixel area on the upper and lower substrates 20 and 25 for convenience.                         

The above-mentioned time division type liquid crystal display device is distinguished from the general liquid crystal display device by the fact that it does not need a color filter and the structure which turns on the R, G, B light source of a backlight unit separately.

However, the conventional FSC liquid crystal display device having the above structure is bonded after the thin film transistor array process and the black matrix layer 21 forming process are independently performed on the lower substrate 20 and the upper substrate 20. In consideration of the bonding margin and the alignment margin, the black matrix layer should be wide on the upper substrate 20.

As described above, when the black matrix layer 21 is widely formed on the upper substrate 20, a problem occurs that the aperture ratio decreases.

In addition, since the black matrix layer 21 formed on the upper substrate 20 has a large reflectance, there is a problem in that visibility is poor when strong external light enters.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a liquid crystal display device and a method of manufacturing the same, which are suitable for solving the misalignment problem of the upper and lower substrates and securing the aperture ratio.

In order to achieve the above object, the liquid crystal display device of the present invention comprises a black matrix layer formed on a region other than the pixel region of the first substrate; A first interlayer insulating film formed on the first substrate including the black matrix layer; Gate lines and data lines formed vertically and horizontally on the first interlayer insulating film to define the pixel areas; A thin film transistor formed of a gate electrode, a source electrode, and a drain electrode at an intersection of the gate line and the data line; A second interlayer insulating film having a contact hole on the drain electrode and formed on the first substrate; A pixel electrode formed on the pixel region to contact the drain electrode through the contact hole; A common electrode facing the first substrate at a predetermined interval and on a front surface thereof; The back of the first substrate, including a R, G, B light source that is sequentially turned on at a predetermined time interval for one frame, the backlight for sequentially supplying R, G, B light to the first substrate side It characterized in that it comprises a second substrate provided with. The gate line, the data line, and the thin film transistor are formed on the black matrix layer.

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The black matrix layer is characterized in that composed of molybdenum (Mo).

The storage lower electrode is further formed on the previous gate line.

The storage upper electrode may be further formed to extend from the pixel electrode to overlap the upper storage lower electrode.

The data line and the storage lower electrode may be formed on the same layer.

According to an aspect of the present invention, there is provided a method of manufacturing a liquid crystal display device, the method including: forming a black matrix layer on a region excluding a pixel region of a first substrate; Forming a first interlayer insulating film on the first substrate including the black matrix layer; Forming a gate line including a gate electrode on the first interlayer insulating film; Forming a gate insulating film on the first substrate including the gate line; Forming an active layer on the gate electrode; Forming a data line, a source electrode, and a drain electrode to intersect the gate line to define the pixel area; Forming a second interlayer insulating film on the drain electrode to have a contact hole; Forming a pixel electrode in the pixel region to contact the drain electrode through the contact hole; Forming a common electrode on the entire surface of the second substrate; Bonding the first and second substrates to face each other at a predetermined interval; And R, G, and B light sources sequentially turned on at a predetermined time interval for one frame, and providing a backlight for sequentially supplying R, G, and B lights to the first substrate. And mounting to the back. The gate line, the data line, and the thin film transistor are formed on the black matrix layer.

The black matrix layer is formed of molybdenum (Mo).

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

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First, a liquid crystal display according to an exemplary embodiment of the present invention will be described.

3 is a plan view of a liquid crystal display according to an exemplary embodiment of the present invention, and FIG. 4 is a cross-sectional view of the structure taken along lines II ′ and II ′ of FIG. 3.

As shown in FIGS. 3 and 4, the liquid crystal display according to the exemplary embodiment of the present invention includes a black matrix layer 61 formed on the transparent lower substrate 60 except for the pixel region, and the black matrix. A first interlayer insulating film 62 formed on the entire surface of the lower substrate 60 including the layer 61, and a gate line 51 and a data line formed vertically and horizontally on the first interlayer insulating film 62 to define a pixel region. And a gate insulating layer formed of a material such as SiNx or SiOx on the entire surface of the lower substrate 60 including the gate electrode 51a protruding from one side of the gate line 51. 52, an active layer 53 formed in an island shape on the gate insulating layer 52 on the gate electrode 51a, and protruding from the data line 54 to upper one side of the active layer 53. A source electrode 54a overlapped with the source and the source A drain electrode 54b spaced apart from the pole 54a at a predetermined interval and overlapping the other side of the active layer 53, a storage lower electrode 54c formed on the previous gate line 51, and the drain electrode 54b ) Is formed on the pixel region so as to be in contact with the drain electrode 54b through the second interlayer insulating film 55 formed on the front surface of the lower substrate 60 so as to have the contact hole 56 exposed therebetween. A pixel electrode 57, a storage upper electrode 57a extending from the pixel electrode 57 and overlapping the storage lower electrode 54c, and an upper portion of the lower substrate 60 including the pixel electrode 57. The first alignment film 58 is formed.

In addition, a common electrode 71 and a second alignment layer 72 are formed on the upper substrate 70 that is opposed to and bonded to the lower substrate 60 at a predetermined interval.

As described above, a thin film transistor including a gate electrode 51a, a source electrode 54a, and a drain electrode 54b is formed at a portion where the gate line 51 and the data line 54 cross each other.

The data line 54 and the storage lower electrode 54c are formed on the same layer.

An ohmic contact layer 53a is formed between the source electrode 54a and the active layer 53 and between the drain electrode 54b and the active layer.

The first and second alignment layers 58 and 72 are made of polyimide.

The black matrix layer 61 is formed under the thin film transistor including the gate electrode 51a and the source and drain electrodes 54a and 54b, and under the gate line 51 and the data line 54. The matrix layer 61 is made of molybdenum (Mo). In this case, as illustrated in the drawing, the black matrix layer 61 may not be formed under the drain electrode 54b in which the contact hole 56 is formed.

The pixel electrode 57 may be formed of indium tin oxide (ITO), tin oxide (TO), indium zinc oxide (IZO), or indium tin zinc oxide (ITZO). It consists of

As described above, the liquid crystal display device according to the present invention is a time-division color (FSC) liquid crystal display device in which no color filter layer is required on the upper substrate 70, and the black matrix layer 61 is formed on the upper substrate 70. The structure formed on the lower substrate 60 is not formed on the substrate).
That is, although not separately shown, the liquid crystal display according to the present invention includes R, G, and B light sources that are mounted on the rear surface of the lower substrate 60 and sequentially light at regular time intervals for one frame. By providing a backlight unit (not shown) for sequentially supplying R, G, and B light on the lower substrate 60 side, a color filter layer for transmitting only light of a specific wavelength band in white light is not required. As such, the liquid crystal display device according to the present invention does not require the provision of the color filter layer, and thus manufacturing cost can be reduced by removing the color filter layer. Here, the liquid crystal display according to the present invention is a liquid crystal cell filled between the lower substrate 60 and the upper substrate 70 and whose cell direction is changed according to an electric field between the pixel electrode 57 and the common electrode 71. The liquid crystal layer may include a ferroelectric liquid crystal (FLC), an optically compensated bend (OCB), or a twisted nematic (TN) liquid crystal mode.

As such, since the common electrode 71 is formed on the entire upper substrate 70 and only the second alignment layer 72 is formed on the common electrode 71, the upper and lower substrates 70 and 60 may be misaligned. There is no misalignment at all. Accordingly, the problem of light leakage due to misalignment does not occur.

The common electrode 71 is composed of ITO, TO, IZO, or ITZO.

In addition, since the present invention is to form a black matrix layer on the lower substrate, it can be expected to increase the aperture ratio than the prior art that the black matrix layer was formed on the upper substrate.                     

In addition, since the area of the black matrix layer 61 formed on the lower substrate 60 is narrower than that of the black matrix layer formed on the upper substrate, the external visibility can be improved.

For reference, the reason why the black matrix layer 61 can be formed on the lower substrate 60 as described above is that the present invention eliminates color mixing at the pixel boundary because no color filter layer is required.

Next, the manufacturing method of the liquid crystal display device which concerns on this invention which has the said structure is demonstrated.

5A through 5D are cross-sectional views illustrating a method of manufacturing a liquid crystal display device according to an exemplary embodiment of the present invention.

In the method of manufacturing the liquid crystal display according to the exemplary embodiment of the present invention, as illustrated in FIG. 5A, a first conductive metal (eg, molybdenum (Mo)) (not shown) is deposited on the transparent lower substrate 60. Thereafter, the first conductive metal is patterned by a photo and etching process to form the black matrix layer 61. In this case, the black matrix layer 61 is formed in the remaining regions except for the region defined as the pixel region.

Thereafter, a first interlayer dielectric layer 62 is formed on the entire lower substrate 60 including the black matrix layer 61.

Next, a second conductive metal is deposited on the first interlayer insulating film 62, and the second conductive metal is patterned by using a photo and etching process to form a gate line 51 arranged in one direction, and the gate line. A gate electrode 51a is formed at 51 to protrude in one direction. In this case, the gate line 51 and the gate electrode 51a are formed on the black matrix layer 61.

Thereafter, the gate insulating layer 52 is formed on the entire surface of the lower substrate 60 on which the gate electrode 51a is formed.

The first interlayer insulating layer 62 and the gate insulating layer 52 may be formed of silicon nitride (SiNx) or silicon oxide (SiO ₂ ).

Subsequently, as shown in FIG. 5B, a semiconductor layer (amorphous silicon (a-Si) + impurity amorphous silicon (n + a-Si)) is formed on the gate insulating film 52.

Subsequently, the semiconductor layer is patterned by photo and etching processes to form an active layer 53 having an island shape on the gate electrode 51a.

Thereafter, a third conductive metal is deposited on the entire surface of the lower substrate 60 on which the active layer 53 is formed, and patterned through photo and etching processes to cross the gate line 51 to define pixel regions. A line 54, a source electrode 54a protruding in one direction from the data line 54, and a drain electrode 54b separated from the source electrode 54a by a predetermined interval are formed.

When the source electrode 54a and the drain electrode 54b are formed, an impurity amorphous silicon layer on the channel region is etched to etch between the source electrode 54a and the active layer 53 and between the drain electrode 54b and the active layer. An ohmic contact layer 53a is formed in between.

In addition, when the source electrode 54a and the drain electrode 54b are formed, the storage lower electrode 54c is formed on the upper gate line.

The data line 54 and the source and drain electrodes 54a and 54b are formed on the black matrix layer 61. In this case, the region of the drain electrode 54b where the contact hole is to be formed later may not be formed on the black matrix layer 61 as shown in the drawing.

Thereafter, as shown in FIG. 5C, a second interlayer insulating film 55 is formed on the entire surface of the lower substrate 60 on which the data line 54 is formed.

The second interlayer insulating layer 55 may be formed using at least one of acryl, polyimide, benzocyclobutene (BCB), silicon oxide film, and silicon nitride film.

Next, a contact hole 56 is formed in the second interlayer insulating layer 55 so that one region of the drain electrode 54b is exposed by a photo and etching process.

Next, after the transparent conductive film is deposited on the entire lower substrate 60 including the second interlayer insulating film 55, the transparent conductive film is etched using the pixel electrode forming mask to form the pixel electrode 57 in the pixel region. .

When forming the pixel electrode 57, the storage upper electrode 57a is formed to extend from the pixel electrode 57 and overlap the storage lower electrode 54c above the previous gate line.

Subsequently, a first alignment layer 58 is formed on the entire surface of the lower substrate 60 including the pixel electrode 57.                     

Subsequently, as shown in FIG. 5D, after forming the common electrode 71 on the entire upper substrate 70 facing the lower substrate 60, the second alignment layer 72 is formed on the common electrode 71. To form.

The common electrode 71 is formed of ITO, IZO, TO, ITZO, or the like on the entire surface of the upper substrate 70 without patterning.

Subsequently, the upper and lower substrates 60 and 70 are bonded to face each other at a predetermined interval.

The first and second alignment layers 58 and 72 are made of polyimide or a photo-alignment material, and the first and second alignment layers 58 and 72 made of polyimide are oriented by mechanical rubbing. The photoreactive material made of a polyvinylcinnamate based material or a polysiloxane based material is determined by the irradiation of light such as ultraviolet rays. In particular, when the first and second alignment layers 58 and 72 are made of a photoreactive material, the alignment direction is determined by the irradiation direction of the light or the property of the irradiated light, that is, the polarization direction.

The process of forming the common electrode 71 on the entire upper substrate 70 may be performed before or simultaneously with the process of forming the black matrix layer 61 on the lower substrate 60.

That is, the process of forming a component on the upper substrate 70 and the process of forming a component on the lower substrate 60 may be performed before or after the same regardless of which process is performed first. .

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention.

Therefore, the technical scope of the present invention is not limited to the contents described in the above embodiments, but may be modified within the scope obvious to those skilled in the art.

The liquid crystal display device according to the present invention having the above configuration has the following effects.

First, since the black matrix layer is formed on the lower substrate and the common electrode is formed on the front surface of the upper substrate, no misalignment problem occurs in the upper and lower substrate bonding processes.

Accordingly, the problem of light leakage due to misalignment can be solved.

Second, since the black matrix layer is formed on the lower substrate, an increase in the aperture ratio can be expected from the prior art of forming the black matrix layer on the upper substrate.

Third, since the area of the black matrix layer formed on the lower substrate is narrower than that of the black matrix layer formed on the upper substrate, the external visibility can be improved.

Claims (10)

A first substrate and a second substrate; A black matrix layer formed on the entirety of the first substrate except for the pixel region; A first interlayer insulating film formed on the first substrate including the black matrix layer; Gate lines and data lines formed vertically and horizontally on the first interlayer insulating film to define the pixel areas; A thin film transistor formed of a gate electrode, a source electrode, and a drain electrode at an intersection of the gate line and the data line; A second interlayer insulating film having a contact hole on the drain electrode and formed on the first substrate; A pixel electrode formed on the pixel region to contact the drain electrode through the contact hole; A common electrode formed on the entire surface of the second substrate; The back of the first substrate, including a R, G, B light source that is sequentially turned on at a predetermined time interval for one frame, the backlight for sequentially supplying R, G, B light to the first substrate side Is provided, And the gate line, the data line, and the thin film transistor are formed on the black matrix layer. delete delete The method of claim 1, And the black matrix layer is made of molybdenum (Mo). The method of claim 1, And a lower storage electrode formed on the previous gate line. The method of claim 5, And a storage upper electrode extending from the pixel electrode to overlap the upper storage lower electrode. The method of claim 5, And the data line and the storage lower electrode are formed on the same layer. Forming a black matrix layer on a region other than the pixel region of the first substrate; Forming a first interlayer insulating film on the first substrate including the black matrix layer; Forming a gate line including a gate electrode on the first interlayer insulating film; Forming a gate insulating film on the first substrate including the gate line; Forming an active layer on the gate electrode; Forming a data line intersecting the gate line to define the pixel region, and a source electrode and a drain electrode on both sides of the upper portion of the active layer; Forming a second interlayer insulating film on the drain electrode to have a contact hole; Forming a pixel electrode in the pixel region to contact the drain electrode through the contact hole; Forming a common electrode on the entire surface of the second substrate; Bonding the first and second substrates to face each other at a predetermined interval; And A backlight including R, G, and B light sources that are sequentially turned on at a predetermined time interval for one frame and sequentially supplying R, G, and B lights to the first substrate is provided on the rear surface of the first substrate. Mounting on, The gate line, the data line, the active layer, the source electrode and the drain electrode are formed on the black matrix layer. The method of claim 8, And the black matrix layer is formed of molybdenum (Mo). delete

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