KR100983704B1 - Liquid crystal display device and method for fabricating thereof - Google Patents

Abstract

The present invention relates to a liquid crystal display device and a method of manufacturing the same that can improve the viewing angle and improve the luminance of reflection in the viewing angle, the first and second substrates; A reflective plate formed on the first substrate and having an asymmetric unevenness having an inclined surface elongated in one direction; And a liquid crystal layer formed between the first and second substrates.

Description

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

1 is a view showing a typical reflective liquid crystal display device.

3 is a view showing a liquid crystal display device according to the present invention.

3A and 3B are graphs showing reflected luminance according to incident / reflected light and reflection angle of a mirror type reflector.

4A and 4B are graphs showing reflected luminance according to incident light / reflected light and a reflection angle of a symmetric uneven reflection plate;

5A and 5B are graphs showing reflected luminance according to incident light / reflected light and reflection angle of an asymmetric uneven reflective plate;

6A to 6D are views showing the manufacturing process of the liquid crystal display device according to the present invention.

7A to 7C are views showing the manufacturing process of the asymmetric unevenness according to the present invention.

8 shows a semi-transmissive area of a rectangle.

9 shows a circular transflective area.

*** Explanation of symbols for main parts of drawing ***

101,201: gate electrodes 105a, 205a: semiconductor layer

105b and 205b: ohmic contact layer 107a and 207a: source electrode                 

107b and 207b Drain electrodes 108 and 208

108a: organic film 111,211 pixel electrode

250: mask

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device and a method of manufacturing the same, which can improve the viewing angle and the reflection brightness.

Liquid crystal display devices are widely applied to such portable information and communication devices because they are light, thin, and low power consumption. However, general transmissive liquid crystal display devices require a backlight device. Power consumption not only shortens the usage time after one-time charging of the portable device, but also causes a problem of poor portability due to the weight and thickness of the backlight.

In addition, since the backlight occupies 80% or more of the power consumption of the transmissive liquid crystal display device having a separate light source unit including a backlight, a reflective liquid crystal without using a backlight to make a low power consumption liquid crystal display device. Display elements are required. In the case of the reflective liquid crystal display device, since the image must be expressed using only external light, maximizing the light efficiency is the maximum research point of the reflective liquid crystal display device. Therefore, many studies have been conducted to improve the light efficiency.

1 is a cross-sectional view of a unit pixel of a general reflective liquid crystal display device.

As shown in the figure, the reflective liquid crystal display device includes a first substrate 10, a second substrate 20, and a liquid crystal layer 30 formed therebetween.

The thin film transistor T is formed on the first substrate 10, which is a switching device that is disposed at each pixel to apply and cut off a signal voltage to the liquid crystal 30, and the thin film transistor T is formed on the first substrate 10. Is a gate electrode 1, a semiconductor layer 5a and an ohmic contact layer 5b formed on the gate electrode 1, and source / drain electrodes 7a and 7b formed on the ohmic contact layer 5b. It consists of. A gate insulating film 3 is disposed between the gate electrode 1 and the semiconductor layer 5a to insulate them, and the thin film transistor T is protected on the source / drain electrodes 7a and 7b. The protective film 9 is formed. In addition, a pixel electrode 11 is formed on the passivation layer 9 of the pixel region, and the pixel electrode 11 is a drain electrode 7b of the thin film transistor T through a contact hole 9a formed on the passivation layer 9. Is electrically connected).

In addition, the second substrate 20 includes a black matrix 2 for preventing light leakage between pixels, a color filter 4 for implementing color, an overcoat film 6 for planarizing the surface of the color filter 4, and A common electrode 12 for applying a voltage to the liquid crystal layer 30 together with the pixel electrode 11 is formed.

In the liquid crystal display device configured as described above, the liquid crystal is driven according to the voltage applied to the common electrode 12 and the pixel electrode 11, thereby controlling the transmittance of light.

In this case, the common electrode 12 is formed of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO), and the pixel electrode 11 is opaque having excellent reflection characteristics such as aluminum or aluminum alloy. It is formed of a metallic material.

Therefore, the pixel electrode 11 drives the liquid crystal 30 and at the same time serves as a reflector reflecting external light. In this case, the pixel electrode and the reflector may be formed separately.

However, in the conventional reflective liquid crystal display device having a mirror type reflective plate as described above, since the surface of the reflective plate is flat, light incident from external light in a specific direction is reflected in the specific direction so that the user is reflected. There was a problem with a narrow viewing angle range where light could be seen.

Accordingly, an object of the present invention is to solve the above problems, and an object of the present invention is to provide a liquid crystal display device having a reflecting plate capable of improving a viewing angle and a method of manufacturing the same.

In addition, another object of the present invention is to provide a liquid crystal display device having a reflecting plate capable of improving the reflectance within the viewing angle and a manufacturing method thereof.

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

The present invention for achieving the above object is the first and second substrate; A reflective plate formed on the first substrate and having an asymmetric unevenness having an inclined surface elongated in one direction; And a liquid crystal layer formed between the first and second substrates. In this case, the reflective plate includes a pixel electrode, and the pixel electrode is made of a metal material having excellent reflection characteristics such as aluminum (Al) or aluminum alloy (AlNd).

The thin film transistor may further include a thin film transistor formed on the first substrate, the thin film transistor comprising: a gate electrode formed on the first substrate; A gate insulating film formed on the gate electrode; A semiconductor layer formed on the gate insulating film; And a source / drain electrode formed on the semiconductor layer.

In addition, each of the concave-convex has asymmetrical shape because the height of the concave-convex from the one side of the concave-convex to the smaller or higher.

In addition, the present invention comprises the steps of preparing a first and a second substrate: forming an asymmetric unevenness having an inclined surface elongated in one direction on the first substrate; Applying a reflective material onto the unevenness; And it provides a method for manufacturing a liquid crystal display device comprising the step of forming a liquid crystal layer between the first and second substrate. The method may further include forming a thin film transistor on the first substrate, and the forming of the thin film transistor may include forming a gate electrode on the first substrate; Forming a gate insulating film on the gate electrode; Forming a semiconductor layer on the gate insulating film; And forming a source / drain electrode on the gate insulating film.

The forming of the asymmetric unevenness may include applying an organic layer on the protective film; The organic layer is formed by using a mask that is divided into a half transmission region and a transmission region of light, and wherein the width of the slit provided in the semi-transmissive region increases or decreases from one side of the semi-transmissive region toward the other side. Exposing; And heat treating the exposed organic layer. In addition, although the semi-transmissive area of the mask may be a circular or rectangular shape, a mask having a semi-transmissive area of another type may be used.

In addition, the present invention comprises the steps of preparing a first and a second substrate; Forming a gate electrode on the first substrate; Forming a gate insulating film on the gate electrode; Forming a semiconductor layer on the gate insulating film; Forming a source / drain electrode on the gate insulating film; Coating an organic layer on an entire surface of the first substrate including the source / drain electrodes; The organic layer is formed by using a mask that is divided into a half transmission region and a transmission region of light, and wherein the width of the slit provided in the semi-transmissive region increases or decreases from one side of the semi-transmissive region toward the other side. Exposing and then developing to form an organic pattern having a plurality of steps; Heat-treating the organic pattern to form irregularities; And it provides a method for manufacturing a liquid crystal display device comprising the step of applying a reflective material on the unevenness.

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

FIG. 2 is a view showing a liquid crystal display device according to the present invention. As shown in the drawing, the liquid crystal display device 100 includes a space between the first and second substrates 110 and 120 and the first and second substrates 110 and 120. It consists of a liquid crystal layer 130 formed on.

The second substrate 120 is formed with a black matrix 102, a color filter 104, and an overcoat layer 106 for planarizing the surface of the color filter 104, and on the liquid crystal layer 130. The common electrode 112 for applying a voltage is formed.

The common electrode 112 is formed of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO).

A thin film transistor T is formed on the first substrate 110, and the thin film transistor T has a gate electrode 101 to which a scan signal is applied and a semiconductor layer 105a that transmits a data signal in response to the scan signal. ), A gate insulator 103 that electrically isolates the semiconductor layer 105a from the gate electrode 101, and a source electrode formed on both sides of the semiconductor layer 105a to apply a data signal. 107a and the ohmic contact layer 105b for reducing contact resistance between the drain electrode 107b for transmitting the data signal to the pixel electrode 111 and the semiconductor layer 105a and the source / drain electrodes 107a and 107b. It consists of. A passivation layer 109 is formed on the thin film transistor T including the source / drain electrodes 107a and 107b to protect the thin film transistor T.

In the thin film transistor T configured as described above, when a scan signal having a high level is applied to the gate electrode 101, a channel through which electrons can move is formed in the semiconductor layer 105a. The data signal of 107a can be transferred to the drain electrode 107b via the semiconductor layer 105a. On the other hand, when a scan signal having a low level is applied to the gate electrode 101, the channel formed in the semiconductor layer 105b is blocked, so that the data signal is stopped to the drain electrode 107b, thereby switching. You will be in charge.

In addition, the pixel electrode 111 electrically connected to the drain electrode 107b and the contact hole 109a is formed on the passivation layer 109 and has an excellent reflecting property such as aluminum or aluminum alloy (AlNd) to reflect external light. It is formed of an opaque metal material such as).

In addition, the pixel electrode 111 is formed in a concave-convex shape on the surface thereof to more effectively reflect external light, thereby improving the viewing angle. Since the concave-convex shape is an asymmetrical line extending in one direction, the luminance of reflection in the viewing angle is increased. Can be further improved.

That is, the reflector plate 125 formed in the pixel region includes an uneven pattern 108 and an opaque metal film coated thereon, that is, the pixel electrode 111. In this case, the pixel electrode 111 not only drives a liquid crystal by applying a voltage to the liquid crystal layer 130 by a signal applied from the drain electrode 107b, but also serves as a reflective film reflecting external light. Therefore, in order to more effectively reflect the external light, the uneven pattern 108 is formed separately so that the surface of the pixel electrode 111 is waved.

The liquid crystal display device of the present invention configured as described above has an advantage that the viewing angle and the reflected brightness can be improved as compared with the prior art. In other words, in the related art (see FIG. 1), since the pixel electrode 11 has a flat reflective surface, light is reflected only in one direction, thereby causing a narrow viewing angle. On the other hand, in the present invention, since the wave is formed on the surface of the pixel electrode 111, the viewing angle can be improved by reflecting external light in various directions. In addition, the uneven pattern 108 to wave the surface of the pixel electrode 111 may be formed in a symmetrical shape having inclined surfaces on both sides, in particular, in the present invention, the surface of the pixel electrode 111 in one direction By making a long lined asymmetric shape, the reflection luminance in the viewing angle range for scanning is further improved.

3A and 3B show the reflectances of the incident light I1 / reflected light R1 and the reflection angle of the mirror-shaped reflector with respect to the conventional mirror-shaped reflector.

As shown in the figure, the incident light I1 incident on the side of the mirror type reflector 201 is intensively reflected only at the same angle as the incident light I1 with respect to the normal direction. At this time, since the incident light I1 generally considers 30 °, the exit angle of the reflected light R1 is concentrated at 30 °. Therefore, as shown in FIG. 3B, the reflectance is very excellent for the same angle of view and the viewing angle, but the viewing angle is not present toward the front reflection angle corresponding to the scanning environment of the user other than the viewing angle (mirror angle). Very narrow

Therefore, the viewing angle problem can be solved by using a symmetrical reflector having an inclined surface.

4A and 4B show incident light I2 / reflected light R2 and thus reflected luminance for a symmetrical reflecting plate having inclined surfaces on both sides, and FIGS. 5A and 5B show asymmetrical reflecting plates having inclined surfaces only in one direction. It shows the incident light (I3) / reflected light (R3) and the reflected luminance accordingly.

First, as shown in FIGS. 4A and 4B, in the symmetrical reflecting plate 301, the light I2 incident on the inclined surface laterally reflects with an angle of incidence and an angle wider than the angle of incidence. At this time, as shown in Figure 4b, the light reflected back at the angle of incidence, that is, the density of the reflected light reflected in the direction of the viewing angle, the highest, there is also a reflected light having a reflection angle smaller or larger than the incident angle. Therefore, there is an advantage that the viewing angle can be improved compared to the mirror-type reflector.

However, since the reflection component A which emits the reflected light in the front direction by the inclined surface of the unevenness inclined in the incident angle direction is substantially the angle at which the user looks at the image by the reflected light, the reflected light reflected in the front is felt by the user. It becomes a component of reflected light. Therefore, the reflected light component B reflected on the inclined surface inclined in the opposite direction does not substantially affect the viewing angle.

Accordingly, the present invention can increase the components of the light reflected in the front direction to the light incident on the axial plane in order to further improve the reflection brightness in the viewing angle and improve the viewing angle, it is possible to reduce the light that does not substantially contribute to securing the viewing angle Reflector structure is required.

As shown in FIGS. 5A and 5B, the light I3 incident on the inclined surface of the asymmetric reflector 401 having the reflective surface inclined in one direction is reflected toward the front direction. At this time, since the area of the inclined surface inclined in the incident angle direction, that is, the inclined surface for emitting the reflected light in the front direction is larger than that of the symmetrical reflecting plate, the component A of the reflected light actually felt by the user increases. Therefore, the reflected luminance can be further improved in the viewing angle range as compared with the symmetrical reflecting plate.

That is, in comparison with FIGS. 4B and 5B, the reflected luminance of the reflected light emitted by the asymmetrical reflector is far higher than that of the asymmetric reflector in the reflected light emitted in the front direction. Will decrease.

The asymmetrical reflecting plate may be formed using a slit mask having a different width of the slit, and the manufacturing method of the liquid crystal display device of the present invention including the asymmetrical reflecting plate as described above will be described.

As shown in FIG. 6A, a transparent first substrate 210 is prepared, and then a thin film transistor T is formed on the first substrate 210. The process of forming the thin film transistor (T) is as follows.

 First, a metal film is deposited on the first substrate 210 and the metal film is patterned through a photo-etching process to form a gate electrode 201a. Subsequently, an inorganic material such as SiNx or SiO 2 is deposited on the entire surface of the first substrate 210 including the gate electrode 201 to form the gate insulating film 203, and then amorphous silicon () is formed on the gate insulating film 203. The n + semiconductor layer doped with amorphous-Si) or polysilicon phosphorus (P) is continuously deposited and then patterned to form the semiconductor layer 205a and the ohmic contact layer 205b. Thereafter, a metal material is deposited on the ohmic contact layer 205b and then patterned to form a source electrode 207a and a drain electrode 207b.

As shown in FIG. 6B, an organic material such as BCB or photoacryl is coated on the entire surface of the source electrode 207a and the drain electrode 207b and the pixel region to form a passivation layer 209 on the thin film transistor. On the gate insulating film 203, asymmetrical irregularities 208 are formed so that the height becomes thicker from one side to the other side. In this case, the unevenness 208 should be formed so that a part of the drain electrode 207 is exposed, and the unevenness 208 is formed through the following process. Although not shown in the drawing, when the protective film is not formed, the unevenness 208 may be formed directly on the gate insulating film 203.

First, as shown in FIG. 7A, an organic layer 208a such as photo-acryl or benzocyclobutene is coated on the gate insulating layer 203, and then a transmission region T The mask 250 divided into a half-transmission region (H) is disposed on the organic layer 208a, and then irradiated with light such as UV (indicated by arrows on the drawing). In this case, the semi-transmissive region (H) of the mask 250 is composed of a plurality of slits that can partially transmit light, the width of the slit increases or decreases from one side to the other side. Accordingly, the light transmittance at one side and the other side is different in the transflective region (H). That is, when the area of the widest slit is called A, the area where the middle slit is defined as B, and the area where light is blocked is C, the light transmittance decreases from A to C. In this case, the transflective region H of the mask 250 may be a quadrangle 250a or a circle 250b as shown in FIGS. 8 and 9.                     

Therefore, when the organic layer 208a is exposed through the mask 250 having the structure as described above and then acted on the developer, as shown in FIG. 7B, the uneven pattern 208b of the asymmetric structure is arranged in one direction. Can be formed. That is, since the exposure amount is greatest in the region A having the widest slit width, the organic layer is removed the most, the organic pattern remains in the region C where the light is blocked, and the region A in the middle slit region B. Since the exposure amount is larger than that, the organic layer is less removed than the organic pattern in the region A, thereby making the organic pattern 208b having a step shape as a whole.

Subsequently, as shown in FIG. 7C, an asymmetric unevenness 208 that is inclined in one direction through the heat treatment (baking) process, that is, becomes thinner or thicker from one side to the other side, may be formed.

At this time, in order to uniformly form the inclined surface of the unevenness 208, when forming the organic pattern 208 (FIG. 7B), the pattern widths of the A, B, and C regions are the same, and AB, BC, and C-substrates (protective films) 209 ) So that the step is uniform.

After forming the unevenness 208 through FIGS. 7A to 7C as described above, as shown in FIG. 6C, reflective characteristics such as Ag, Ag alloy, Al, and Al alloy (AlNd) are formed on the unevenness 208. The excellent metal material is coated and then patterned to form a pixel electrode 211 electrically connected to the drain electrode 207b through the contact hole 209a.

Subsequently, as shown in FIG. 6D, the first substrate 220 and the black matrix 202, the color filter 204, and the common electrode 212 on which the thin film transistor T and the pixel electrode 211 are formed are formed. After the second substrate 210 is bonded to each other, the liquid crystal layer 230 is formed therebetween, whereby a liquid crystal display device capable of improving the viewing angle and the reflected luminance within the viewing angle can be formed.

As described above, the present invention can improve the viewing angle by forming irregularities on the surface of the pixel electrode, and inclining the irregularities in one direction to increase the reflected light emitted from the front, thereby further improving the luminance of reflection in the viewing angle. .

Claims (18)

delete delete delete delete delete delete delete delete delete Preparing the first and second substrates: Forming a gate electrode on the first substrate; Forming a gate insulating film on the gate electrode; Forming a semiconductor layer on the gate insulating film; And Forming a source / drain electrode on the gate insulating film; Applying an organic layer on the first substrate; A mask including a transmissive region (H) for partially transmitting the light is disposed on the organic layer and includes a transmissive region (T) of light and a plurality of slits, wherein the transflective region (H) is the width of the slit. The first area A and the second area B, the widest first area A, the second area B having a slit width in the middle, and the third area C where light is blocked. And the length and width of each of the third region C are the same, The organic layer is exposed and developed through the mask to correspond to the first region A, the second region B, and the third region C, respectively, and the organic patterns have a stepped shape with different thicknesses of the organic layers. Forming a; Heat treating the staircase-shaped organic pattern to form an asymmetric uneven pattern having an inclined surface with one side extending in one direction; Forming a pixel electrode connected to the drain electrode on the asymmetric uneven pattern and functioning as a reflecting plate; And Forming a liquid crystal layer between the first and second substrates. delete delete delete The method of claim 10, wherein the semi-transmissive region of the mask is formed in a circular shape. The method of claim 10, wherein the semi-transmissive region of the mask is formed in a rectangular shape. Preparing first and second substrates; Forming a gate electrode on the first substrate; Forming a gate insulating film on the gate electrode; Forming a semiconductor layer on the gate insulating film; Forming a source / drain electrode on the gate insulating film; Coating an organic layer on an entire surface of the first substrate including the source / drain electrodes; A mask including a transmissive region (H) for partially transmitting the light is disposed on the organic layer and includes a transmissive region (T) of light and a plurality of slits, wherein the transflective region (H) is the width of the slit. The first area A and the second area B, the widest first area A, the second area B having a slit width in the middle, and the third area C where light is blocked. And the length and width of each of the third region C are the same, The organic layer is exposed and developed through the mask to correspond to the first region A, the second region B, and the third region C, respectively, and the organic patterns have a stepped shape with different thicknesses of the organic layers. Forming a; Heat treating the staircase-shaped organic pattern to form an asymmetric uneven pattern having an inclined surface with one side extending in one direction; Applying a reflective material connected to the drain electrode on the asymmetric unevenness; And Selectively patterning the reflective material to form a pixel electrode functioning as a reflecting plate; Method of manufacturing a liquid crystal display device comprising a. delete 17. The method of claim 16, wherein the reflective material is Al or AlNd.

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