KR100934846B1 - Reflective type liquid crystal display device and manufacturing method - Google Patents

Abstract

The reflective liquid crystal display device and a method of manufacturing the same according to the present invention implement a single gamma by adjusting the angles of the reflecting portion and the transmitting portion, and at the same time using a low twisted nematic (LTN) liquid crystal. A fourth substrate for implementing a high phase retardation value compared to a conventional phase delay plate by implementing a quarter wave delay plate (QWP), the first substrate having a pixel part divided into a plurality of reflection parts and a transmission part; A gate electrode and a gate line formed on the pixel portion of the first substrate, and a reflective electrode formed on the reflective portion of the first substrate; A first insulating film formed on the first substrate; An active pattern formed on the gate electrode; A data line formed on the first substrate and defining a pixel region crossing the source / drain electrode and the gate line electrically connected to the source / drain region of the active pattern; A pixel electrode formed in the pixel region including the reflecting portion and the transmitting portion and electrically connected to the drain electrode; A second insulating film formed on the first substrate; A common electrode formed in a single pattern over the entire pixel portion of the first substrate, the common electrode having a plurality of first slits in the transmission portion and a plurality of second slits in the reflection portion; A second substrate joined to face the first substrate; And a low twisted nematic liquid crystal layer formed between the first substrate and the second substrate, wherein the first slit is disposed in the same direction with respect to the data line, while the second slit is predetermined with respect to the data line. It is inclined at an angle, and the common electrode is formed on the data line, so that the aperture ratio is improved.

Description

Reflective liquid crystal display device and manufacturing method therefor {TRANS-REFLECTIVE LIQUID CRYSTAL DISPLAY DEVICE AND METHOD OF FABRICATING THE SAME}

The present invention relates to a transflective liquid crystal display device and a method for manufacturing the same, and more particularly, to a transflective liquid crystal display device and a method of manufacturing the same that can selectively use both reflection and transmission mode.

Recently, with increasing interest in information display and increasing demand for using a portable information carrier, a lightweight flat panel display (FPD), which replaces a conventional display device, a cathode ray tube (CRT), is used. The research and commercialization of Korea is focused on. In particular, the liquid crystal display (LCD) of the flat panel display device is an image representing the image using the optical anisotropy of the liquid crystal, is excellent in resolution, color display and image quality, and is actively applied to notebooks or desktop monitors have.

The liquid crystal display is largely composed of a color filter substrate and an array substrate, and a liquid crystal layer formed between the color filter substrate and the array substrate.

The active matrix (AM) method, which is a driving method mainly used in the liquid crystal display device, uses an amorphous silicon thin film transistor (a-Si TFT) as a switching device to drive the liquid crystal in the pixel portion. to be.

Hereinafter, a structure of a general liquid crystal display device will be described in detail with reference to FIG. 1.

1 is an exploded perspective view schematically illustrating a general liquid crystal display.

As shown in the figure, the liquid crystal display device is largely a liquid crystal layer (liquid crystal layer) formed between the color filter substrate 5 and the array substrate 10 and the color filter substrate 5 and the array substrate 10 ( 30).

The color filter substrate 5 includes a color filter C composed of a plurality of sub-color filters 7 for implementing colors of red (R), green (G), and blue (B); A black matrix 6 that separates the sub-color filters 7 and blocks light passing through the liquid crystal layer 30, and a transparent common electrode that applies a voltage to the liquid crystal layer 30. 8)

In addition, the array substrate 10 may be arranged vertically and horizontally to define a plurality of gate lines 16 and data lines 17 and a plurality of gate lines 16 and data lines 17 that define a plurality of pixel regions P. The thin film transistor T, which is a switching element formed in the cross region, and the pixel electrode 18 formed on the pixel region P, are formed.

The color filter substrate 5 and the array substrate 10 configured as described above are joined to face each other by a sealant (not shown) formed outside the image display area to form a liquid crystal display panel. The bonding of the 5 and the array substrate 10 is made through a bonding key (not shown) formed on the color filter substrate 5 or the array substrate 10.

The liquid crystal display device configured as described above may be classified into a transmission type and a reflection type according to a light source to be used.

In this case, the transmissive liquid crystal display is a form in which an artificial light emitted from a backlight, which is a back light source attached to the rear side of the liquid crystal display panel, is incident on the liquid crystal to display the color by adjusting the amount of light according to the arrangement of the liquid crystals. The type liquid crystal display is a form in which light transmittance is adjusted according to the arrangement of liquid crystals by reflecting external natural light or artificial light source.

Since the transmissive liquid crystal display uses an artificial back light source, a bright image can be realized even in a dark external environment. However, the power consumption of the transmissive liquid crystal display is large. Since the structure depends on the light source, power consumption is lower than that of the transmissive liquid crystal display, but it cannot be used in a dark place.

Accordingly, a reflection-transmissive liquid crystal display device has been proposed as a device capable of appropriately selecting and using two modes according to a necessary situation.

Such a transflective liquid crystal display generally uses a normally white mode in which white light is output when no voltage is applied. Since the reflection mode is designed based on the reflection mode, the transmittance of the transmissive mode when no voltage is applied is determined. It is only about 50% of the reflection mode transmittance. In addition, in the transmitting part, the light supplied from the backlight is directly transmitted to the outside through the liquid crystal layer, but in the case of the reflecting part, the external light source is reflected from the reflective electrode through the liquid crystal layer and then transmitted to the outside through the liquid crystal layer. When is applied, the phase difference change in the liquid crystal layer and the reflection electrode cannot be the same between the reflection portion and the transmission portion.

In order to solve the problem in the single cell gap structure, a liquid crystal display device having a dual cell gap structure, which has a structure in which the transmission cell gap is larger than the reflection cell gap, has been proposed.

Hereinafter, the reflective transmissive liquid crystal display device having the dual cell gap structure will be described in detail through a method of manufacturing the same. For reference, a method of reducing the number of masks in terms of productivity is required because a manufacturing process of the liquid crystal display device basically requires a plurality of mask processes (ie, photolithography) for fabricating an array substrate including a thin film transistor. This is required.

2A to 2G are cross-sectional views sequentially illustrating a manufacturing process of a general reflective transmissive liquid crystal display device, and showing a manufacturing process of a reflective transmissive liquid crystal display device having a dual cell gap structure in which a cell gap of a transmissive part is larger than a cell gap of a reflective part. .

As shown in FIG. 2A, a gate electrode 21 made of a conductive metal material is formed on the array substrate 10 using a photolithography process (first mask process).

Next, as shown in FIG. 2B, the first insulating film 15a, the amorphous silicon thin film, and the n + amorphous silicon thin film are sequentially deposited on the entire surface of the array substrate 10 on which the gate electrode 21 is formed. Subsequently, an active pattern 24 made of the amorphous silicon thin film is formed on the gate electrode 21 by selectively patterning the amorphous silicon thin film and the n + amorphous silicon thin film by using a photolithography process (second mask process).

In this case, an n + amorphous silicon thin film pattern 25 patterned in the same shape as the active pattern 24 is formed on the active pattern 24.

Thereafter, as illustrated in FIG. 2C, a conductive metal material is deposited on the entire surface of the array substrate 10 and then selectively patterned using a photolithography process (third mask process) to form a source on the active pattern 24. The electrode 22 and the drain electrode 23 are formed. In this case, the n + amorphous silicon thin film pattern formed on the active pattern 24 has a predetermined region removed through the third mask process, thereby forming an ohmic − between the active pattern 24 and the source / drain electrodes 22 and 23. An ohmic contact layer 25n is formed.

Next, as shown in FIG. 2D, the second insulating film 15b, which is an organic insulating film such as acrylic, is deposited on the entire surface of the array substrate 10 on which the source electrode 22 and the drain electrode 23 are formed. Thereafter, a portion of the second insulating layer 15b is removed through a photolithography process (fourth mask process) to adjust the cell gap of the contact hole 40 and the transmission portion exposing a portion of the drain electrode 23. An open hole T is formed.

As shown in FIG. 2E, a conductive metal material having excellent reflectance is deposited on the entire surface of the array substrate 10 on which the second insulating film 15b is formed, and then, using a photolithography process (a fifth mask process). The reflective electrode 18r is formed to be electrically connected to the drain electrode 23 through the contact hole 40.

Next, as shown in FIG. 2F, after the transparent conductive metal material is deposited on the entire surface of the array substrate 10, the reflective electrode 18r is formed using a photolithography process (sixth mask process). The pixel electrode 18t is formed in the entire pixel region including the reflector.

As described above, a general reflective transmissive liquid crystal display device requires a total of six photolithography processes to manufacture an array substrate including a thin film transistor, and thus requires a larger number of photolithography processes than a transmissive liquid crystal display device.

The photolithography process is a series of processes in which a pattern drawn on a mask is transferred onto a substrate on which a thin film is deposited to form a desired pattern. The photolithography process includes a plurality of processes such as photoresist coating, exposure, and development processes. It has the disadvantage of dropping.

In particular, a mask designed to form a pattern is very expensive, and as the number of masks applied to the process increases, the manufacturing cost of the liquid crystal display device increases in proportion thereto.

The array substrate 10 fabricated as described above is bonded to the upper surface of the color filter substrate 5 as shown in FIG. 2G by a sealant formed on the outer side of the image display area to form a liquid crystal display device.

In this case, the color filter substrate 5 includes a black matrix 6 that prevents light leakage into the thin film transistor, the gate line, and the data line, and a color filter 7 for realizing red, green, and blue colors. A predetermined overcoat layer 9 and a common electrode 8 are formed on the black matrix 6 and the color filter 7.

A liquid crystal layer (not shown) is interposed between the color filter substrate 5 and the array substrate 10 configured as described above, and the thickness of the liquid crystal layer is defined as cell gaps d1 and d2.

Here, in order to reduce the difference in the phase difference value of the light due to the difference in the light travel distance in the reflector and the light travel distance in the transmissive part, the light travel distance in the reflector is equal to the travel distance of the light in the transmissive part. In consideration of being doubled, the reflector cell gap d1 is designed to correspond to 1/2 of the transmissive cell gap d2 having an open hole in the second insulating layer 15b.

However, the reflection type liquid crystal display device having the dual cell gap structure has the following problems.

First, an organic insulating material having excellent step characteristics is mainly used to provide a cell gap difference between the reflecting part and the transmitting part. In the case of the organic insulating material, a separate process equipment is required and the cost is high.

Second, depending on the step of the insulating film, the process of varying the cell gap between the reflective portion and the transmissive portion requires a substantially complex process condition, thereby reducing the process efficiency.

In addition, in order to implement a reflection type transverse electric field (IPS) liquid crystal display device for a wide viewing angle, there are problems that a plurality of retardation compensation films must be applied.

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 reflective transmissive liquid crystal display device and a method of manufacturing the same in which an array substrate is manufactured by five mask processes.

Another object of the present invention is to provide a reflective transmissive liquid crystal display device and a method of manufacturing the same by improving a mask process by forming a reflective electrode when forming a gate electrode.

Another object of the present invention is to provide a reflection type liquid crystal display device and a method of manufacturing the same, which can implement the reflection type wide viewing angle mode with a single cell gap.

Other objects and features of the present invention will be described in the configuration and claims of the invention described below.

In order to achieve the above object, the reflection-transmissive liquid crystal display device of the present invention comprises a first substrate having a pixel portion divided into a plurality of reflecting portion and the transmission portion; A gate electrode and a gate line formed on the pixel portion of the first substrate, and a reflective electrode formed on the reflective portion of the first substrate; A first insulating film formed on the first substrate; An active pattern formed on the gate electrode; A data line formed on the first substrate and defining a pixel region crossing the source / drain electrode and the gate line electrically connected to the source / drain region of the active pattern; A pixel electrode formed in the pixel region including the reflecting portion and the transmitting portion and electrically connected to the drain electrode; A second insulating film formed on the first substrate; A common electrode formed in a single pattern over the entire pixel portion of the first substrate, the common electrode having a plurality of first slits in the transmission portion and a plurality of second slits in the reflection portion; A second substrate joined to face the first substrate; And a low twisted nematic liquid crystal layer formed between the first substrate and the second substrate, wherein the first slit is disposed in the same direction with respect to the data line, while the second slit is predetermined with respect to the data line. It is inclined at an angle, and the common electrode is formed on the data line, so that the aperture ratio is improved.

In addition, the method of manufacturing a reflective transmissive liquid crystal display device of the present invention comprises the steps of providing a first substrate having a plurality of reflecting portion and the pixel portion divided into a transmission portion; Forming a gate electrode and a gate line on the pixel portion of the first substrate, and forming a reflective electrode on the reflective portion of the first substrate; Forming a first insulating film on the first substrate; Forming a data line on the first substrate to define a pixel region by crossing an active pattern, a source / drain electrode, and the gate line; Forming a pixel electrode on the pixel area including the reflecting part and the transmitting part, the pixel electrode being electrically connected to the drain electrode; Forming a second insulating film on the first substrate; Forming a common electrode in a single pattern over the entire pixel portion of the first substrate, wherein the common electrode has a plurality of first slits in the transmission portion and a plurality of second slits in the reflection portion; Forming a low twisted nematic liquid crystal layer between the first substrate and the second substrate; And bonding the first substrate and the second substrate, wherein the first slit is disposed in the same direction with respect to the data line, while the second slit is formed to be inclined at a predetermined angle with respect to the data line. The common electrode may be formed on the data line to improve the aperture ratio.

As described above, the reflective liquid crystal display device and the method of manufacturing the same according to the present invention provide an effect of reducing the number of masks used for manufacturing the thin film transistor and reducing the manufacturing process and cost.

In addition, the reflective liquid crystal display device and the manufacturing method thereof according to the present invention can realize a reflective wide viewing angle with one λ / 4 phase delay plate and two λ / 2 phase delay plates, and by implementing a single cell gap, The yield and productivity can be improved compared to the dual cell gap.

In addition, the reflection-transmissive liquid crystal display device and the manufacturing method thereof according to the present invention can obtain a high phase delay value compared to a conventional phase delay plate when implementing a λ / 4 phase delay plate with a low twisted nematic liquid crystal, thereby improving luminance efficiency of a transmission part. It can be effective.

In addition, the reflective liquid crystal display device and the method of manufacturing the same according to the present invention provide an advantage of easily implementing a single gamma by adjusting the electrode angle of the reflecting unit and the transmitting unit.

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

FIG. 3 is a plan view schematically illustrating a portion of an array substrate of a reflective transmissive liquid crystal display according to an exemplary embodiment of the present invention. For convenience of description, one pixel including a thin film transistor including a gate pad part, a data pad part, and a pixel part is provided. It is shown.

In an actual liquid crystal display device, N gate lines and M data lines intersect and MxN pixels exist, but one pixel is shown in the figure for simplicity of explanation.

In addition, the transflective liquid crystal display device according to the embodiment of the present invention is an In Plane Switching (IPS) type liquid crystal display device in which a liquid crystal molecule is driven in a horizontal direction with respect to a substrate to improve the viewing angle to 170 degrees or more. In particular, FIG. 3 illustrates a fringe field switching method for implementing an image by driving a fringe field formed between a pixel electrode and a common electrode to drive liquid crystal molecules positioned on the pixel region and the pixel electrode through a slit; FFS) The liquid crystal display device is shown as an example.

As shown in the drawing, an array substrate 110 according to an embodiment of the present invention is arranged on the array substrate 110 divided into a reflecting portion (R) and a transmission portion (T) in a vertical direction to define a pixel area of the gate Line 116 and data line 117 are formed. In addition, a thin film transistor, which is a switching element, is formed in an intersection area between the gate line 116 and the data line 117, and a plurality of slits for driving a liquid crystal (not shown) by generating a fringe field in the pixel area. The common electrode 108 having the 108s and 108s ', the pixel electrode 118 and the reflective electrode 118' in the form of a box are formed.

Here, the reflection-transmissive liquid crystal display device according to the embodiment of the present invention is a λ / 4 phase delay using a low twisted nematic liquid crystal having a twist angle of about 63 to 64 ° to the liquid crystal, preferably 63.5 ° or 63.6 °. By implementing the plate it is possible to obtain a high phase delay value compared to the existing phase delay plate is characterized in that to improve the luminance efficiency of the transmission (T).

In this case, a portion of the gate line 116 positioned at the front end may overlap a portion of the pixel electrode 118 therebetween with a first insulating layer (not shown) therebetween to form a storage capacitor. The storage capacitor serves to maintain a constant voltage applied to the liquid crystal capacitor until the next signal. That is, the pixel electrode 118 of the array substrate 110 forms a liquid crystal capacitor together with the common electrode 108. In general, the voltage applied to the liquid crystal capacitor is not maintained until the next signal is input and is leaked. Disappear. Therefore, in order to maintain the applied voltage, the storage capacitor must be connected to the liquid crystal capacitor.

In addition to maintaining the signal, the storage capacitor has effects such as stabilization of gray scale display and reduction of flicker and afterimage.

The thin film transistor includes a gate electrode 121 connected to the gate line 116, a source electrode 122 connected to the data line 117, and a drain electrode 123 electrically connected to the pixel electrode 118. It is. In addition, the thin film transistor includes an active pattern 124 that forms a conductive channel between the source electrode 122 and the drain electrode 123 by a gate voltage supplied to the gate electrode 121.

In this case, a part of the source electrode 122 extends in one direction to form a part of the data line 117, and a part of the drain electrode 123 extends toward the pixel area to directly contact the pixel electrode without a separate contact hole. 118 is electrically connected.

As described above, a common electrode 108 having a plurality of slits 108s and 108s ', a pixel electrode 118, and a reflective electrode 118' is formed in the pixel region. The pixel electrode 118 is formed over the entire pixel area, that is, the entire reflective part R and the transmissive part T, while the reflective electrode 118 ′ is formed only in the reflective part R to provide an external light source. It will act as a reflection.

In addition, the common electrode 108 is formed in a single pattern over the entire pixel portion, and a plurality of first slits 108s in the transmission portion T and a plurality of second slits in the reflection portion R are formed. And 108s').

In this case, the first slit 108s is disposed in substantially the same direction with respect to the data line 117, while the second slit 108s ′ has a predetermined angle with respect to the data line 117. It is disposed so as to generate the same effect as rubbing in different directions in the reflecting portion (R) and the transmission portion (T). This is a method for realizing a single gamma in the reflecting part R and the transmitting part T. The electrode of the reflecting part R, that is, the second slit 108s compared with the electrode of the transmitting part T, that is, the first slit 108s. ') Is inclined at about 30-40 °, preferably 35 °.

In addition, when the common electrode 108 is formed in a single pattern over the entire pixel portion, it is necessary to form a common line for electrically connecting the common electrodes as compared with the case where the common electrode is formed in each pixel region. There will be no. As a result, the number of masks required to fabricate the array substrate 110 can be reduced by one.

In addition, since the opaque common line is not required as described above, the common electrode 108 is also formed on the data line 117, thereby improving the aperture ratio. It is present in the outermost first slit 108s around the data line 117 to maximize the transmittance around the data line 117.

The gate pad electrode 126p and the data pad electrode 127p electrically connected to the gate line 116 and the data line 117 are formed in the edge region of the array substrate 110 configured as described above. The scan signal and the data signal applied from the driving circuit unit (not shown) are transferred to the gate line 116 and the data line 117, respectively.

That is, the gate line 116 and the data line 117 extend toward the driving circuit part and are connected to the corresponding gate pad line 116p and the data pad line 117p, respectively, and the gate pad line 116p and the data pad The line 117p receives the scan signal and the data signal from the driving circuit unit through the gate pad electrode 126p and the data pad electrode 127p electrically connected to the gate pad line 116p and the data pad line 117p, respectively. You will be authorized.

For reference, reference numerals 140a and 140b indicate a first contact hole and a second contact hole, respectively, wherein the data pad electrode 127p is electrically connected to the data pad line 117p through the first contact hole 140a. The gate pad electrode 126p is electrically connected to the gate pad line 116p through the second contact hole 140b.

Here, the reflective liquid crystal display device according to the embodiment of the present invention uses a half-tone mask or a diffraction mask (hereinafter referred to as a half-tone mask to include a diffraction mask) and an active pattern and a source / By forming a drain electrode and a data line in a single mask process and forming a pixel electrode to directly connect the drain electrode without a separate contact hole, the number of masks required to fabricate an array substrate can be reduced.

In addition, the reflective liquid crystal display device according to the embodiment of the present invention allows the reflective electrode array substrate to be manufactured by a total of five mask processes by forming the reflective electrode when forming the gate electrode, and the reflective transmissive wide viewing angle mode with a single cell gap. It will be possible to implement, which will be described in detail through the manufacturing method of the following reflection-transmissive liquid crystal display device.

4A through 4E are cross-sectional views sequentially illustrating a manufacturing process along lines IIIa-IIIa ', IIIb-IIIb, and IIIc-IIIc of the array substrate illustrated in FIG. 3, and a process of manufacturing an array substrate of a pixel portion is shown on the left side. The right side shows a step of manufacturing an array substrate of a data pad part and a gate pad part in order.

5A to 5E are plan views sequentially illustrating a manufacturing process of the array substrate illustrated in FIG. 3.

As shown in FIGS. 4A and 5A, the gate electrode 121, the gate line 116, and the reflective electrode 118 ′ are formed in the pixel portion of the array substrate 110 made of a transparent insulating material such as glass. A gate pad line 116p is formed in the gate pad portion of the array substrate 110.

In this case, the gate electrode 121, the gate line 116, the reflective electrode 118 ′, and the gate pad line 116p deposit a first conductive layer on the entire surface of the array substrate 110 and then perform a photolithography process. It is formed by selectively patterning through a mask process).

Here, the first conductive layer may include aluminum (Al), aluminum alloy (Al alloy), tungsten (W), copper (Cu), chromium (Cr), molybdenum (Mo), and Low resistance opaque conductive materials such as molybdenum alloys can be used. In addition, the first conductive layer may have a multilayer structure in which two or more low resistance conductive materials are stacked.

As described above, when the gate electrode 121 and the gate line 116 are formed, the reflective liquid crystal display according to the exemplary embodiment of the present invention forms the reflective electrode 118 'by the first conductive layer to form the reflective electrode. The number of masks required for the formation of 118 'can be reduced.

Next, as shown in FIGS. 4B and 5B, the gate electrode 121, the gate line 116, the reflective electrode 118 ′, and the gate pad line 116p are formed on the entire surface of the array substrate 110. The first insulating film 115a, the amorphous silicon thin film, the n + amorphous silicon thin film, and the second conductive film are formed.

Thereafter, the amorphous silicon thin film, the n + amorphous silicon thin film, and the second conductive film are selectively removed through a photolithography process (second mask process) to form an active pattern including the amorphous silicon thin film in the pixel portion of the array substrate 110 ( 124 is formed, and a source electrode 122 and a drain electrode 123 formed of the second conductive layer are formed on the active pattern 124.

In this case, a data line 117 made of the second conductive layer is formed in the data line region of the array substrate 110 through the second mask process, and the second data pad portion of the array substrate 110 is formed. A data pad line 117p made of a conductive film is formed.

In this case, a first n + amorphous silicon thin film pattern 125 ′ formed of the n + amorphous silicon thin film and patterned in the same shape as the active pattern 124 is formed on the active pattern 124.

In addition, the first amorphous silicon thin film pattern 124 ′ and the second amorphous silicon thin film and the n + amorphous silicon thin film respectively formed under the data pad line 117p and patterned in the same shape as the data pad line 117p. An n + amorphous silicon thin film pattern 125 "is formed.

Here, the active pattern 124, the source / drain electrodes 122 and 123, and the data line 117 according to an exemplary embodiment of the present invention use a half-tone mask to perform one mask process (second mask process). Simultaneously, the second mask process will be described in detail with reference to the accompanying drawings. However, the present invention is not limited thereto, and the active pattern 124, the source / drain electrodes 122 and 123, and the data line 117 may be formed by two mask processes.

6A through 6F are cross-sectional views illustrating a second mask process according to an exemplary embodiment of the present invention in the array substrate illustrated in FIGS. 4B and 5B.

As shown in FIG. 6A, the first insulating film 115a is formed on the entire surface of the array substrate 110 on which the gate electrode 121, the gate line 116, the reflective electrode 118 ′, and the gate pad line 116p are formed. An amorphous silicon thin film 120, an n + amorphous silicon thin film 125, and a second conductive film 130 are formed.

In this case, the second conductive layer 130 may be made of a low resistance opaque conductive material such as aluminum, aluminum alloy, tungsten, copper, chromium, molybdenum and molybdenum alloy to form a source electrode, a drain electrode, and a data line.

6B, after forming the first photoresist film 170 made of photosensitive material such as photoresist on the entire surface of the array substrate 110, the first half-tone mask according to the embodiment of the present invention. Light is selectively irradiated to the first photoresist layer 170 through 180.

In this case, the first half-tone mask 180 blocks the first transmission region I transmitting all of the irradiated light and the second transmission region II transmitting only a part of the light and blocking part of the light and all the irradiated light. The blocking region III is provided, and only the light passing through the first half-tone mask 180 is irradiated to the first photosensitive film 170.

Subsequently, after developing the first photoresist layer 170 exposed through the first half-tone mask 180, as shown in FIG. 6C, the blocking region III and the second transmission region II are formed. The first photoresist layer pattern 170a to the fourth photoresist layer pattern 170d having a predetermined thickness remain in the region where all of the light is blocked or partially blocked by the light, and the first transmission region I through which all the light is transmitted The first photoresist film is completely removed to expose the surface of the second conductive film 130.

In this case, the first photoresist pattern 170a to the third photoresist pattern 170c formed in the blocking region III are formed thicker than the fourth photoresist pattern 170d formed through the second transmission region II. In addition, the first photoresist film is completely removed in a region where all light is transmitted through the first transmission region I. This is because a positive type photoresist is used, and the present invention is not limited thereto. May be used as the photoresist.

Next, as shown in FIG. 6D, the amorphous silicon thin film, the n + amorphous silicon thin film, and the second formed on the lower portion of the first photosensitive film pattern 170a to the fourth photosensitive film pattern 170d formed as described above are used as a mask. When the conductive film is selectively removed, an active pattern 124 made of the amorphous silicon thin film is formed on the pixel portion of the array substrate 110, and the second conductive layer is formed on the data line portion of the array substrate 110. A data line (not shown) is formed.

In addition, a data pad line 117p formed of the second conductive layer is formed in the data pad part of the array substrate 110.

In this case, the first n + amorphous silicon thin film pattern 125 ′ and the second conductive layer formed of the n + amorphous silicon thin film and the second conductive layer and patterned in the same shape as the active pattern 124, respectively, on the active pattern 124. The conductive film pattern 130 ′ is formed.

In addition, the first amorphous silicon thin film pattern 124 ′ and the second amorphous silicon thin film and the n + amorphous silicon thin film respectively formed under the data pad line 117p and patterned in the same shape as the data pad line 117p. An n + amorphous silicon thin film pattern 125 "is formed.

Thereafter, as illustrated in FIG. 6E, an ashing process of removing a portion of the first to fourth photoresist patterns may be performed to completely remove the fourth photoresist pattern of the second transmission region II. .

In this case, the first photoresist pattern to the third photoresist pattern correspond to the blocking region III by the fifth photoresist pattern 170a 'through the seventh photoresist pattern 170c', in which the thickness of the fourth photoresist pattern is removed. Only the source electrode region and the drain electrode region and the upper portion of the data pad line 117p remain.

6F, the array substrate 110 is removed by removing a portion of the second conductive film pattern using the remaining fifth photoresist pattern 170a ′ to seventh photoresist pattern 170c ′ as a mask. A source electrode 122 and a drain electrode 123 formed of the second conductive film are formed in the pixel portion.

In this case, the first n + amorphous silicon thin film pattern 125 ′ formed of an n + amorphous silicon thin film remains on the active pattern 124, and is formed on the entire surface of the array substrate 110 to form a pixel electrode to be described later. When the third conductive layer is deposited, the channel region of the active pattern 124, specifically, the back channel, may be prevented from being contaminated by the deposition of the third conductive layer.

As described above, according to the exemplary embodiment of the present invention, the active pattern 124, the source / drain electrodes 122 and 123, and the data line 117 may be formed through a single mask process by using a half-tone mask.

Next, as illustrated in FIGS. 4C and 5C, a third conductive layer is formed on the entire surface of the array substrate 110 on which the active patterns 124, the source / drain electrodes 122 and 123, and the data lines 117 are formed. do.

Thereafter, the third conductive film is selectively patterned using a photolithography process (third mask process) to form a pixel electrode 118 directly connected to the drain electrode 123 in the pixel portion of the array substrate 110. do.

In this case, the first n + amorphous silicon thin film pattern may be selectively removed through the third mask process to ohmic contact between the source / drain region of the active pattern 124 and the source / drain electrodes 122 and 123. The ohmic contact layer 125n is formed.

As described above, according to the exemplary embodiment of the present invention, the pixel electrode 118 and the ohmic contact layer 125n may be formed through a single mask process by using a half-tone mask in the third mask process. It will be described in detail with reference to the drawings. However, the present invention is not limited thereto, and the ohmic contact layer 125n may be formed during the process of forming the source electrode 122 and the drain electrode 123 in the second mask process.

7A to 7F are cross-sectional views illustrating a third mask process according to an exemplary embodiment of the present invention in the array substrate illustrated in FIGS. 4C and 5C.

As shown in FIG. 7A, a third conductive layer 150 is formed on the entire surface of the array substrate 110 on which the active pattern 124, the source / drain electrodes 122 and 123, and a data line (not shown) are formed. .

In this case, the third conductive layer includes a transparent conductive material having excellent transmittance such as indium tin oxide (ITO) or indium zinc oxide (IZO) to form a pixel electrode.

In this case, when the first n + amorphous silicon thin film pattern 125 ′ remains on the channel region of the active pattern 124 as described above, the back channel of the active pattern 124 is deposited by the deposition of the third conductive layer. This can prevent the contamination.

As shown in FIG. 7B, the second half-tone mask according to the embodiment of the present invention is formed after forming the second photoresist layer 175 formed of a photoresist such as photoresist on the entire surface of the array substrate 110. Light is selectively irradiated to the second photoresist layer 175 through 185.

In this case, the second half-tone mask 185 blocks the first transmission region I through which all of the irradiated light is transmitted and the second transmission region II through which only a part of the light is transmitted and partly blocks the light. The blocking region III is provided, and only the light passing through the second half-tone mask 185 is irradiated to the second photosensitive film 175.

Subsequently, after developing the second photoresist layer 175 exposed through the second half-tone mask 185, as shown in FIG. 7C, the blocking region III and the second transmission region II are formed. The first photoresist pattern 175a and the second photoresist pattern 175b having a predetermined thickness remain in the region where all of the light is blocked or partially blocked by the light, and the first transmission region I through which all the light is transmitted The second photoresist film is completely removed to expose the surface of the third conductive film 150.

In this case, the first photoresist pattern 175a formed in the blocking region III is thicker than the second photoresist pattern 175b formed through the second transmission region II. In addition, the second photoresist film is completely removed in a region where all light is transmitted through the first transmission region I. This is because a positive type photoresist is used, and the present invention is not limited thereto. May be used as the photoresist.

Next, as shown in FIG. 7D, the second conductive film and the first n + amorphous silicon thin film formed below the first photosensitive film pattern 175a and the second photosensitive film pattern 175b formed as a mask are used as masks. When the pattern is selectively removed, an ohmic contact layer 125n formed of the n + amorphous silicon thin film and patterned in the same shape as the source / drain 122 and 123 is formed in the pixel portion of the array substrate 110. Will be.

In this case, the ohmic contact layer 125n serves to ohmic contact between the source / drain region of the active pattern 124 and the source / drain electrodes 122 and 123.

Subsequently, as shown in FIG. 7E, an ashing process of removing a portion of the first photoresist layer pattern and the second photoresist layer pattern is performed to completely remove the second photoresist layer pattern of the second transmission region II.

In this case, the first photoresist layer pattern is a third photoresist layer pattern 175a 'from which the thickness of the second photoresist layer pattern is removed and remains only in the pixel electrode region corresponding to the blocking region III.

Subsequently, as shown in FIG. 7F, a portion of the third conductive film is removed by using the remaining third photoresist pattern 175a ′ as a mask to transfer the third conductive film to the pixel portion of the array substrate 110. The pixel electrode 118 thus formed is formed.

In this case, the pixel electrode 118 may be directly connected to a part of the drain electrode 123 without a separate contact hole, thereby eliminating a mask process required to form the contact hole.

Next, as shown in FIGS. 4D and 5D, after forming the second insulating film 115b on the entire surface of the array substrate 110 on which the pixel electrode 118 is formed, the photolithography process (fourth mask process) is performed. The first contact hole 140a and the second contact hole 140a expose a portion of the data pad line 117p and the gate pad line 116p to the data pad part and the gate pad part of the array substrate 110 by selectively removing the insulating film. The contact hole 140b is formed.

In this case, the reflective transmissive liquid crystal display according to the exemplary embodiment of the present invention does not form an open hole for removing a part of the second insulating layer 115b of the transmissive part, thereby realizing a single cell gap in which the cell gap of the transmissive part is the same as the cell gap of the reflective part. Done.

4E and 5E, a fourth conductive film formed of a transparent conductive material is formed on the entire surface of the second insulating film 115b in which the first contact hole 140a and the second contact hole 140b are formed. Thereafter, by selectively patterning using a photolithography process (a fifth mask process), the common electrode having a plurality of first slits 108s in the transmission portion and a plurality of second slits 108s' in the reflection portion 108).

In this case, by selectively patterning the fourth conductive layer using the fifth mask process, the data pad portion and the gate pad portion respectively pass through the first contact hole 140a and the second contact hole 140b. The data pad electrode 127p and the gate pad electrode 126p electrically connected to the line 117p and the gate pad line 116p are formed.

In this case, the fourth conductive layer is a transparent conductive material having excellent transmittance such as indium tin oxide or indium zinc oxide to form the common electrode 108, the data pad electrode 127p, and the gate pad electrode 126p. It includes.

In addition, the common electrode 108 according to the embodiment of the present invention is formed in a single pattern over the entire pixel portion, and a plurality of first slits in the common electrode 108 in the transmission portion where the pixel electrode 118 is formed. 108s are formed, and a plurality of second slits 108s 'are formed in the reflective part in which the pixel electrode 118 and the reflective electrode 118' are formed.

In this case, since the common electrode 108 is formed in a single pattern over the entire pixel portion, the gate line 116 and the data are regions in which the plurality of first slits 108s and the second slits 108s' are not formed. It is also formed on the line 117 and the thin film transistor. For reference, the pixel unit refers to an image display area of the array substrate 110 in which all pixel areas are collected to display an image.

In particular, in the reflective liquid crystal display according to the exemplary embodiment of the present invention, since the common electrode 108 is also formed on the data line 117, the aperture ratio of the liquid crystal display panel is improved, and the transmissive part has left and right sides of the pixel electrode 118. The tip is present in the outermost first slit 108s around the data line 117 to maximize the transmittance around the data line 117.

In addition, the pixel electrode 118 is directly overlapped with the drain electrode 124 of the thin film transistor to form a contact hole for connecting the pixel electrode 118 and the drain electrode 123. Do not need to be formed in the pixel region, thereby increasing the aperture ratio of the pixel region.

The array substrate according to the embodiment of the present invention configured as described above is bonded to the color filter substrate by a sealant formed on the outside of the image display area, wherein the color filter substrate includes light through the thin film transistor, the gate line, and the data line. Black matrix to prevent leakage and color filter for red, green and blue color are formed.

At this time, the bonding of the color filter substrate and the array substrate is made through a bonding key formed on the color filter substrate or the array substrate.

Meanwhile, as described above, the reflective transmissive liquid crystal display according to the embodiment of the present invention implements a λ / 4 phase delay plate (QWP) using low twisted nematic (LTN) liquid crystal. In the cell gap structure, the luminance efficiency of the transmission part can be improved while single gamma can be realized by adjusting the angles of the electrodes of the reflection part and the transmission part, which will be described in detail with reference to the accompanying drawings.

8A and 8B are graphs schematically showing the electro-optical characteristics of the LTN horizontal switching cell according to the change of the orientation angle, and FIG. 8A illustrates the electro-optical characteristics of the LTN horizontal switching cell according to the change of the orientation angle in the reflector. 8b shows the electro-optic characteristics of the LTN horizontal switching cell according to the change of the orientation angle in the transmission part.

For reference, in the calculation process, a positive type liquid crystal having a dielectric constant anisotropy Δε and a refractive index anisotropy Δn value of 0.0778 and +13.1, respectively, was used. In addition, the electrode width (inter-slit spacing) and the electrode interval (slit width) were set to 4 micrometers which is the minimum pattern level which the general mass-production equipment forms. The cell gap was set to 2.5 μm in consideration of the liquid crystal value in order to satisfy the phase delay value of 194 nm.

9 is a plan view showing the angles of orientation of the reflecting portion and the transmitting portion in the reflective transmissive liquid crystal display device according to the embodiment of the present invention.

10A and 10B are graphs showing the electro-optic characteristics of the transmissive part and the reflecting part, and the electro-optical characteristics of the transmissive part and the reflecting part are simulated when the transmissive part is oriented at 5 ° relative to the electrode and the reflector is oriented at -30 ° relative to the electrode. And through measurement.

In general, in the case of IPS (In Plane Switching) mode and FFS (Fringe Field Switching) mode, the change of cell transmittance according to the applied voltage, that is, the electro-optic characteristic, is oriented at an angle with respect to the electrode between the electrodes and the alignment process. The characteristics vary depending on whether you do it.

8A and 8B, simulation results show that the transmittance and reflectance depend on the orientation angle with respect to the electrode. This means that when the angles of orientation of the transmissive part and the reflecting part are different, it is possible to display the same gradation with the single gamma.

When combining the transmittance and reflectance according to the orientation angle with respect to the electrode, as shown in FIGS. 8A, 8B, and 10A, the transmissive part is oriented at 5 ° relative to the electrode and the reflector is oriented at -30 ° relative to the electrode as shown in FIGS. The most similar electro-optic properties could be obtained.

In order to verify this, two cells having different orientation angles under the same conditions were manufactured and experimentally measured. As shown in FIG. 10C, it was confirmed that the electro-optic characteristics of the transmission part and the reflection part were identical.

At this time, the cell is applied to the 2.0 inch cell which is currently produced in FFS mode, the array substrate is in FFS mode and the electrode width and the distance between the electrodes are 4㎛, respectively, and the dielectric anisotropy Δε and the refractive index anisotropy Δn are 0.0609 and +10.9, respectively. Positive type liquid crystal having was used. The cell gap was designed to be 3.2㎛ to satisfy the retardation value of 194nm of the liquid crystal, and all processes except for the alignment process proceeded the same, and only the alignment angles were 5 ° and -30 ° relative to the electrode direction during the alignment process. The cells were fabricated in different ways.

 Accordingly, as shown in FIG. 9, in the embodiment of the present invention, the angle of the electrode of the reflector relative to the transmissive part, or the second slit 108s' of the reflective part relative to the first slit 108 of the transmissive part is preferably 30 to 40 °. Preferably, the single gamma can be realized in the transmission part and the reflection part by adjusting the angle to 35 ° and performing rubbing only once at an angle α of 1 to 10 °, preferably 5 °, with respect to the first slit 108 of the transmission part. .

11A and 11B illustrate a parameter space diagram for calculating ΔS of an LTN cell.

12A and 12B schematically illustrate an optical structure of an LTN liquid crystal cell according to an exemplary embodiment of the present invention. FIG. 12A shows an optical structure of an LTN liquid crystal cell in a black state, and FIG. 12B shows an LTN liquid crystal in a white state. The optical structure of the cell is shown.

In order for an LTN cell to achieve an optimal black state, an optimal design of the twist angle and phase delay value of the TN cell is required. In order to realize an optimal black state with zero reflectance of the reflector, the TN liquid crystal layer itself should serve as a λ / 4 phase delay plate (QWP).

As the light passing through the TN liquid crystal layer is closer to the perfect circular polarization, the light reflected from the reflective electrode is completely blocked by the polarizing plate and the reflectance is reduced. Will be zero.

So, the output light from above, should be as close as possible to circular polarization. Therefore, the following ΔS can be defined, and since ΔS is the difference between the final output light and the ideal circular polarization, the smaller the difference is, the closer the circular polarization of the output light is.

As a result of calculating the twist angle and phase delay value of the liquid crystal layer using a parameter space diagram to calculate Equation 2, as shown in FIGS. 11A and 11B, the twist angle of 63.6 ° at the reference design wavelength of 550 nm. And a phase delay value of 194 nm. Under this condition, the polarizer and the TN liquid crystal layer act as λ / 4 phase delay plates.

That is, as shown in FIG. 12A, the black state of the transmissive part is arranged by arranging the polarizing plate and the λ / 4 phase delay plate orthogonal to the combination of the polarizing plate and the TN liquid crystal layer serving as the λ / 4 phase delay plate on the back of the reflective electrode. It is possible to realize black state by canceling phase delay.

In addition, in order to obtain a white state of both the reflecting unit and the transmitting unit, a horizontal electric field is applied to the liquid crystal layer so that the phase delay value inside the cell is changed while the liquid crystal rotates in the horizontal direction.

As shown in Fig. 12B, the reflecting part white state is arranged such that the liquid crystal layer twisted by the applied horizontal electric field is rotated horizontally and is aligned with the transmission axis of the upper polarizing plate in the same 0 ° direction as the transmission axis of the upper polarizing plate. If the incident light is linearly polarized through the polarizer, the phase delay of the liquid crystal layer may not be felt during the reciprocation of the liquid crystal layer. Accordingly, the white state can be realized by the incident linearly polarized light reaching the upper polarizer without any phase change. The transmissive white state implementation shows that as the electric field is applied, most of the liquid crystal molecules in the transmissive region are arranged along the optical axis of the λ / 4 phase delay plate in the lower plate except near the alignment layer which is held by the strong anchoring energy. . As a result, the combination of the LTN liquid crystal layer and the λ / 4 phase delay plate in the lower plate exhibits the phase delay effect of the λ / 2 phase delay layer with an optical axis of -45 °. Accordingly, the light linearly polarized at 90 ° through the lower polarizer passes through the λ / 4 phase delay plate and the LTN liquid crystal layer, and almost feels the λ / 2 phase delay. The light is changed to 0 ° polarized light and passes through the upper polarizer. White state is implemented.

As described above, the reflection-transmissive liquid crystal display device according to the embodiment of the present invention can obtain a high phase delay value compared to the existing phase delay plate by implementing the λ / 4 phase delay plate with LTN liquid crystal, thereby improving the luminance efficiency of the transmission part. Will be.

In addition, as shown in FIGS. 12A and 12B, the reflective transmissive liquid crystal display according to the exemplary embodiment of the present invention can realize the reflective wide viewing angle with one λ / 4 phase delay plate and two λ / 2 phase delay plates. Will be.

The embodiment of the present invention describes an amorphous silicon thin film transistor using an amorphous silicon thin film as an active pattern as an example, but the present invention is not limited thereto, and the present invention is a polycrystalline silicon thin film using a polycrystalline silicon thin film as the active pattern. The same applies to transistors.

In addition, the present invention can be used not only in liquid crystal display devices but also in other display devices fabricated using thin film transistors, for example, organic light emitting display devices in which organic light emitting diodes (OLEDs) are connected to driving transistors. have.

Many details are set forth in the foregoing description but should be construed as illustrative of preferred embodiments rather than to limit the scope of the invention. Therefore, the invention should not be defined by the described embodiments, but should be defined by the claims and their equivalents.

1 is an exploded perspective view schematically showing a general liquid crystal display device.

2A to 2G are cross-sectional views sequentially illustrating a manufacturing process of a general reflective transmissive liquid crystal display device.

3 is a plan view schematically illustrating a portion of an array substrate of a transflective liquid crystal display according to an exemplary embodiment of the present invention.

4A to 4E are cross-sectional views sequentially showing manufacturing processes taken along lines IIIa-IIIa ', IIIb-IIIb and IIIc-IIIc of the array substrate shown in FIG.

5A through 5E are plan views sequentially illustrating a manufacturing process of the array substrate illustrated in FIG. 3.

6A to 6F are cross-sectional views illustrating a second mask process according to an embodiment of the present invention in the array substrate shown in FIGS. 4B and 5B.

7A to 7F are cross-sectional views illustrating a third mask process according to an exemplary embodiment of the present invention in the array substrate shown in FIGS. 4C and 5C.

8A and 8B are graphs schematically showing electro-optical characteristics of LTN horizontal switching cells with a change in orientation angle.

FIG. 9 is a plan view showing an angle of orientation of a reflecting portion and a transmitting portion in the reflective transmissive liquid crystal display device according to the embodiment of the present invention; FIG.

10A and 10B are graphs showing the electro-optical characteristics of the transmission part and the reflection part through simulation and measurement.

11A and 11B show a parameter space diagram for calculating ΔS of LTN cells.

12A and 12B schematically illustrate an optical structure of an LTN liquid crystal cell according to an embodiment of the present invention.

** Explanation of symbols for main parts of drawings **

108: common electrode 108s, 108s': slit

110: array substrate 116: gate line

117 data line 118 pixel electrode

118 ': reflective electrode 121: gate electrode

122 source electrode 123 drain electrode

124: active pattern

Claims (13)

Providing a first substrate having a pixel portion divided into a plurality of reflection portions and a transmission portion; Forming a gate electrode and a gate line on the pixel portion of the first substrate, and forming a reflective electrode on the reflective portion of the first substrate; Forming a first insulating film on the first substrate; Forming a data line on the first substrate to define a pixel region by crossing an active pattern, a source / drain electrode, and the gate line; Forming a pixel electrode on the pixel area including the reflecting part and the transmitting part, the pixel electrode being electrically connected to the drain electrode; Forming a second insulating film on the first substrate; Forming a common electrode in a single pattern over the entire pixel portion of the first substrate, wherein the common electrode has a plurality of first slits in the transmission portion and a plurality of second slits in the reflection portion; Forming a low twisted nematic liquid crystal layer between the first substrate and the second substrate; And And bonding the first substrate and the second substrate, wherein the first slit is disposed in the same direction with respect to the data line, while the second slit is formed to be inclined at a predetermined angle with respect to the data line. And the common electrode is formed on the data line to improve the aperture ratio. The method of claim 1, wherein forming an active pattern and a source / drain electrode on the first substrate is performed. Forming an active pattern on the gate electrode with the first insulating layer interposed therebetween, and forming a source / drain electrode on the active pattern to electrically connect the source / drain regions of the active pattern; And And forming an n + amorphous silicon thin film pattern patterned in the same shape as the active pattern on the active pattern. 3. The method of claim 2, wherein the forming of the pixel electrode in the pixel region including the reflecting portion and the transmitting portion forms a pixel electrode in the pixel region so as to directly connect with a portion of the drain electrode. And removing a portion to form an ohmic contact layer. The method of manufacturing a reflective transmissive liquid crystal display device according to claim 1, wherein a low twisted nematic liquid crystal having a twist angle of 63 to 64 ° is formed between the first substrate and the second substrate. The method of claim 1, wherein the second slit of the reflector is formed to be inclined at an angle of 30 to 40 degrees with respect to the data line. The method of claim 1, further comprising forming an alignment layer on the surfaces of the first substrate and the second substrate. The method of claim 1, further comprising rubbing the alignment layer of the first substrate at an angle of about 1 ° to about 10 ° with respect to the first slit. A first substrate having a pixel portion divided into a plurality of reflection portions and a transmission portion; A gate electrode and a gate line formed on the pixel portion of the first substrate, and a reflective electrode formed on the reflective portion of the first substrate; A first insulating film formed on the first substrate; An active pattern formed on the gate electrode; A data line formed on the first substrate and defining a pixel region crossing the source / drain electrode and the gate line electrically connected to the source / drain region of the active pattern; A pixel electrode formed in the pixel region including the reflecting portion and the transmitting portion and electrically connected to the drain electrode; A second insulating film formed on the first substrate; A common electrode formed in a single pattern over the entire pixel portion of the first substrate, the common electrode having a plurality of first slits in the transmission portion and a plurality of second slits in the reflection portion; A second substrate joined to face the first substrate; And A low twisted nematic liquid crystal layer formed between the first substrate and the second substrate, wherein the first slit is disposed in the same direction with respect to the data line, while the second slit is at an angle with respect to the data line. Wherein the common electrode is formed on the data line to improve the aperture ratio. The liquid crystal display of claim 8, wherein the low twisted nematic liquid crystal layer is formed of a low twisted nematic liquid crystal having a twist angle of 63 to 64 degrees. The liquid crystal display of claim 8, wherein the second slit of the reflector is inclined at an angle of 30 to 40 degrees with respect to the data line. The liquid crystal display device according to claim 8, further comprising an alignment layer formed on the surfaces of the first substrate and the second substrate. 12. The film of claim 11, wherein the alignment film of the transmissive part is oriented at an angle of 5 ° with respect to the first slit, and the alignment film of the reflective part is oriented at an angle of -30 ° with respect to the second slit. Reflective type liquid crystal display device. The liquid crystal display of claim 8, wherein the cell gaps of the transmissive part and the reflecting part are the same.

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