KR20040016221A - Reflective Liquid Crystal Device display and Manufacturing for the same - Google Patents

Abstract

PURPOSE: A reflection type liquid crystal display and its fabrication method are provided to increase directivity to a user by forming an asymmetrical unevenness on a surface of a reflection electrode. CONSTITUTION: A gate line and a data line(62) are formed longitudinally and laterally to define a pixel area. A reflection electrode(63) has a number of asymmetrical unevenness(64) and is formed on the pixel area. And a thin film transistor is formed on a cross point of the gate line and the data line. The asymmetrical unevenness has different slopes at both sides, and has a gradual slope toward one direction.

Description

Reflective Liquid Crystal Display and Manufacturing Method for the Same

The present invention relates to a display device, and more particularly, to a reflective liquid crystal display device and a manufacturing method thereof.

Recently, due to the rapid development of the information and communication field, the importance of the display industry for displaying desired information is increasing day by day, and to date, CRT (cathod ray tube) among information display devices can display various colors and display brightness It has also enjoyed steady popularity so far because of its superiority.

However, there is an urgent need for the development of flat panel displays instead of CRTs that are bulky and bulky due to the desire for large, portable and high resolution displays. These flat panel displays have a wide range of applications from computer monitors to displays used in aircraft and spacecraft.

Currently produced or developed flat panel displays include liquid crystal display (LCD), electro luminescent display (ELD), field emission display (FED), plasma display panel (PDP), etc. In order to achieve an ideal flat panel display, light weight, high brightness, high efficiency, high resolution, high speed response characteristics, low driving voltage, low power consumption, low cost, and color display characteristics are required. Among such flat panel displays, the liquid crystal display device is in the spotlight because of its durability as well as its desire.

On the other hand, the liquid crystal display device is an image display device using the optical anisotropy characteristics of the liquid crystal, and when the light is irradiated to the liquid crystal exhibiting polarization characteristics according to the voltage applied state of the liquid crystal display device according to the alignment state of the liquid crystal It is a device that can express the image by adjusting the amount.

In order to configure the liquid crystal display device, a liquid crystal panel including the liquid crystal layer and a circuit disposed around the liquid crystal panel to apply a signal to the liquid crystal panel and control the signal are further required.

Hereinafter, a general transmissive liquid crystal display device will be described with reference to the accompanying drawings.

1 is a schematic perspective view of a general transmissive liquid crystal display device.

As shown in FIG. 1, the transmissive liquid crystal display device includes a liquid crystal panel 10 including an upper substrate 11, a lower substrate 12, and a liquid crystal layer 13 formed between the two substrates for expressing color; The first and second polarizers 14 and 15 are disposed on the liquid crystal panel 10 so that the polarizers 19 cross each other.

Although not shown, the liquid crystal panel 10 further includes a backlight, which is a light source, and a light guide plate, a reflecting plate, a diffusion plate, and a prism for transmitting light emitted from the backlight.

Here, the first and second polarizing plates 14 and 15 have a characteristic in which the polarization direction is vertical.

The lower substrate 12 may also be referred to as an array substrate, and a thin film transistor (not shown), which is a switching element, and a pixel electrode (not shown) for displaying an image are located in a matrix type. In order to operate the thin film transistor, the gate wiring 16 and the data wiring 17 are formed to be orthogonal to each other. In addition, a common electrode (not shown) is formed on the upper substrate 11.

Pixel electrodes (not shown) and common electrodes (not shown) respectively formed on the lower substrate 12 and the upper substrate 11 are indium-tin oxides for transmitting light emitted from the backlight. -oxide: It is composed of transparent conductive metal such as ITO).

The liquid crystal molecules 18 of the liquid crystal layer 13 formed between the upper substrate 11 and the lower substrate 12 are formed by the alignment layer (not shown) formed on the surfaces of the two substrates facing each other. The azimuth angles from 12) to the upper substrate 11 are twisted by 90 degrees.

That is, white light irradiated from the backlight is polarized in one direction by the second polarizing plate 15, and light polarized by the second polarizing plate 15 is refracted by the lower substrate 12 and the liquid crystal layer 13. do.

At this time, as shown, the light incident on the liquid crystal layer 13 is refracted to be orthogonal to the direction polarized by the second polarizing plate 15 by rotating the azimuth angle by 90 degrees by the twisting of the liquid crystal molecules 18. . As such, the intensity of transmitted light may be adjusted by adjusting the azimuth or polar angle of the liquid crystal molecules 18 in the liquid crystal layer 13.

In addition, the white light refracted by the liquid crystal layer 13 passes through the upper substrate 11 on which a color filter (not shown) capable of expressing an RGB color is formed, and the upper substrate 11 has a color. Light passes through the first polarizing plate 14 and is represented as an image.

Accordingly, the transmissive liquid crystal display may implement an image by controlling the intensity of transmitted light after expressing polarization and refraction using light irradiated from the backlight and expressing color.

However, the transmissive liquid crystal display device using such a backlight is not only limited to manufacturing ultra-light and ultra-thin by increasing the weight and volume by the backlight and its integral structure to irradiate light from the rear, but also to drive the backlight. There is a problem that power consumption is increased accordingly.

In order to solve such a problem, research on a reflective liquid crystal display device using external light as a light source has been actively conducted.

2 is a schematic perspective view of a reflective liquid crystal display device.

As shown in FIG. 2, the reflective LCD includes a liquid crystal panel 24 including an upper substrate 21, a lower substrate 22, and a liquid crystal layer 23 interposed between the two substrates, and the liquid crystal panel. The polarizing plate 25 arrange | positioned on 24 is comprised.

Although not shown, each pixel area on the lower substrate 22 further includes a reflective electrode formed to reflect external light.

In addition, the polarizing plate 25 transmits light that vibrates in a specific direction perpendicular to the traveling direction of light and absorbs the remaining components.

That is, as shown in the figure, when no voltage is applied to the liquid crystal panel 24, the reflective liquid crystal display device has external light polarized by the polarizing plate 25, and the polarized external light has an upper substrate ( 21 and the liquid crystal layer 23 are refracted by the reflective electrode of the lower substrate 22 and then refracted by the liquid crystal layer 23, and the color filter of the upper substrate 21 (not shown). By passing through), an image can be realized.

On the other hand, when a voltage is applied to the liquid crystal panel 24, the light polarized by the polarizing plate 25 is rotated with the azimuth angle of the liquid crystal molecule 26 to be reflected on the reflective electrode and reflected on the reflective electrode. The light is refracted by the liquid crystal layer 23 and is incident on the polarizer 25 so as to be absorbed by the polarizer 25.

For example, a plurality of elements such as the scattering film 21 and the retardation plate 23 may be further included to artificially control the polarization state of the external light polarized by the polarizing plate 25.

In this case, the scattering film 21 is to scatter light to provide a wider viewing angle from the observer's point of view, the phase difference plate 23 is the right circular polarization (RCP) ) Or left circular polarization (LCP).

Accordingly, the reflective liquid crystal display device may transmit or absorb the external light reflected by the control of the liquid crystal molecules 26, and may widen the viewing angle from the reflected and transmitted external light by using the scattering plate and the phase difference plate. have.

Such a reflective liquid crystal display will be described in detail with reference to the accompanying drawings.

3 is a plan view of a typical reflective liquid crystal display device. As shown in FIG. 3, a general reflective liquid crystal display device includes gate lines 31 and data lines 32 formed vertically and horizontally to define pixel regions (not shown), and pixels corresponding to the pixel regions. A gate electrode 34, a gate insulating film (not shown), a semiconductor layer 36, a source / drain electrode 37a, at a portion where the electrode 33 and the gate wiring 31 and the data wiring 32 cross each other; A thin film transistor composed of 37b) is formed.

The thin film transistor is a switching element, and may apply a data signal to the pixel electrode 33 by a switching signal applied to the gate electrode 27.

In addition, the pixel electrode 33 reflects external light to the opaque reflective electrode 33 having high reflectivity.

4 is a cross-sectional view taken along line II ′ of FIG. 3, in which a general reflective liquid crystal display device includes a gate electrode 43 protruding from a gate wire (not shown) formed in one direction on the lower substrate 42, and A gate insulating film 44 formed on the lower substrate 42 including the gate electrode 43, a semiconductor layer 45 formed in an island shape on the gate insulating film 44 corresponding to the gate electrode 43, and And a passivation layer 46 formed on the lower substrate 42 including the source / drain electrodes 47a and 47b formed on both sides of the semiconductor layer 45, and the source / drain electrodes 47a and 47b. The reflective electrode 48 is formed on the passivation layer 46 of the pixel region to be electrically connected to the electrode 47b, and the first alignment layer 49a is formed on the reflective electrode 48.

In this case, there is a thin film transistor including the gate electrode 43, the gate insulating layer 44, the semiconductor layer 45, and the source / drain electrodes 47a and 47b. In addition, the reflective electrode 48 which contacts the drain electrode 47b through a drain contact hole (not shown) is driven by an opaque conductive metal material having a high reflectance (not shown) to drive external light and It serves to reflect.

Next, on the upper substrate 41 facing the lower substrate 42, a color formed in each pixel region between the black matrix 50 and the black matrix 50 for blocking light at portions other than the pixel region. A filter 51, a common electrode 52 formed on the color filter 51, and a second alignment layer 49b formed on the common electrode 52 are provided. A liquid crystal layer 53 formed between the two substrates is further formed.

In addition, the reflective liquid crystal display device further includes a separate diffusion plate 54 on the upper substrate 41 as shown.

Because the brightness of the liquid crystal display is not good as the light reflected by the reflective electrode 48 and emitted to the outside, a separate diffuser plate 54 is attached to the upper portion of the upper substrate 41 so that the diffuser plate is provided. By using the diffused light of the light at 54, a liquid crystal display device having high luminance is produced.

However, such a structure does not require a separate process when fabricating the lower substrate 42, but requires a separate diffusion plate 54 to be attached, and thus it is difficult to obtain an ultra-thin liquid crystal display device, and thus a manufacturing cost of the liquid crystal display device. This has the drawback.

A reflection type liquid crystal display device has been proposed to compensate for such drawbacks.

5 is a plan view of another conventional reflective liquid crystal display device, and FIG. 6 is a cross-sectional view taken along line II-II 'of FIG. 5.

As shown in FIG. 5, another conventional reflective liquid crystal display device includes a gate line 31 and a data line 32 formed vertically and horizontally to define a pixel area on a lower substrate (not shown). The reflective electrode 33 formed with a plurality of pits 38 in the pixel region and the gate wiring 31 and the data wiring 32 are formed at intersections thereof. And a thin film transistor T for applying a signal of a data line to the reflective electrode 33.

Here, the plurality of pits 38 are formed to diffusely reflect the incident external light by forming recessed portions having a predetermined interval on the flat reflective electrode 33 surface.

6 is a cross-sectional view taken along line II-II 'of FIG. 5, in which a plurality of the pits 38 formed on the reflective electrode 48 etch a protective film at regular intervals to diffusely reflect the incident external light to form a trench. As a result, the reflective electrode 48 having the fit 38 may be formed.

Accordingly, another conventional reflective liquid crystal display device may diffusely reflect external light by using the plurality of pits 38 formed on the lower substrate 42 at predetermined intervals.

However, since the fit 38 that can be formed in one reflective electrode is limited, there is a problem that the luminance is lowered.

Another prior art reflective liquid crystal display device has been proposed to solve this problem.

7 is a plan view of another conventional reflective liquid crystal display device.

As shown in FIG. 7, another conventional reflective liquid crystal display device includes a gate line 31 and a data line 32 formed vertically and horizontally to define a pixel area on a lower substrate (not shown). The reflective electrode 33 formed on the pixel area and having a plurality of symmetrical irregularities 39 for diffusely reflecting the incident external light, and formed at a portion where the gate wiring 31 and the data wiring 32 cross each other; The thin film transistor T is configured to apply the signal of the data line 32 according to the signal of the gate line 31.

Here, the symmetrical concave-convex 39 is formed to have a wavy curve on the surface of the reflective electrode 33 to diffuse the light diffusely.

FIG. 8 is a cross-sectional view taken along line III-III ′ of FIG. 7, and another conventional reflective liquid crystal display device includes a gate electrode 43 protruding from a gate line (not shown) formed in one direction on a lower substrate 42. And a gate insulating film 44 formed on the entire surface of the lower substrate 42 including the gate electrode 43, a semiconductor layer 45 formed in an island shape on the gate insulating film 44, and the semiconductor layer ( 45 is connected to the source / drain electrodes 47a and 47b formed on both sides, the passivation layer 46 formed on the lower substrate 42 including the source / drain electrodes 47a and 47b, and the drain electrode 47b. And a reflective electrode 48 formed on the passivation layer 46.

At this time, the upper surface of the protective film 46 is formed with a wavy symmetrical irregularities 39, the reflective electrode 48 is formed in the same shape along the upper surface of the protective film 46.

Therefore, another conventional reflective liquid crystal display device can increase luminance by diffusely reflecting the incident light of external light using the reflective electrode 48 formed to have the symmetrical irregularities 39.

Looking at the manufacturing method of another conventional reflective liquid crystal display device configured as described above are as follows.

First, a conductive metal material such as molybdenum (Mo), tungsten (W), chromium (Cr), and an aluminum alloy is deposited and patterned on the lower substrate 42 to form a gate wiring in one direction (not shown) and the gate wiring. The protruding gate electrode 43 is formed.

In addition, the gate insulating layer 44 is formed on an entire surface of the substrate including the gate electrode 43 by using an insulating material such as silicon nitride (SiNx) or silicon oxide (SiOx).

Next, an amorphous silicon and an amorphous silicon containing impurities are deposited and patterned on the gate insulating layer 44 to form a semiconductor layer 45 in an island shape in a portion corresponding to the gate electrode.

In addition, a data line (not shown) intersecting the gate line by depositing and patterning a conductive metal on the entire surface of the substrate on which the semiconductor layer 45 is formed, and protruding from the data line above the gate electrode 43. A source electrode 47a and a drain electrode 47b spaced apart from the source electrode 47a by a predetermined interval are formed.

Next, a passivation layer 46 is formed on the lower substrate 42 on which the source / drain electrodes 47a and 47b are formed using an inorganic insulating layer, an organic insulating layer, or a photosensitive layer, and then a drain contact hole is formed in the drain electrode 47b. (Not shown).

In addition, a plurality of symmetrical irregularities 39 are formed on the surface of the protective layer 46, which is a lower layer of the reflective electrode 48, to diffusely reflect external light.

In this case, when the protective film 46 is formed of the inorganic insulating film, symmetrical irregularities 39 may be formed on the protective film by a photolithography method using PR, and the protective film 46 is formed of the organic insulating film. In addition, a plurality of symmetrical irregularities 39 may be formed on the surface of the passivation layer 46 by dry etching using a material such as SF ₆ + O ₂ or oxygen ashing.

Thereafter, an opaque conductive metal having excellent reflective properties such as aluminum is deposited and patterned on the passivation layer 46 having the plurality of symmetrical irregularities 39 formed thereon to form the reflective electrode 48. In this case, the reflective electrode 48 formed of aluminum may be deposited on the curved protective layer 46 without being lifted because of excellent contact with the protective layer.

Next, a first alignment layer 49a may be further formed on the reflective electrode 48 to align the liquid crystal molecules (not shown).

Finally, the black matrix 50, the color filter 51, the common electrode 52, and the second alignment layer 49b are formed on the upper substrate corresponding to the lower substrate 42, and the two substrates are bonded to each other. After finishing the injection of the liquid crystal 53 between the two substrates.

However, another conventional reflective liquid crystal display device has the following problems.

FIG. 9 is a view schematically illustrating reflection of incident light in a conventional reflective electrode having symmetrical unevenness, which is along the surface of the symmetrical unevenness 39 when the incident light 55 is irradiated to the symmetrical unevenness 39 in one direction. It can be seen that the light is reflected in a random direction.

When the symmetrical concave-convex 39 is used as the reflecting surface as described above, light efficiency is lowered because the incident light 55 irradiated from the light source of the indoor or outdoor cannot be condensed to be viewed at a desired angle from the user.

For example, a reflective liquid crystal display device such as a personal portable terminal does not need a wide viewing angle, and can be displayed at a specific viewing angle that is easy for a user to handle the portable terminal.

Accordingly, the conventional reflective liquid crystal display device has the following problems.

First, when the reflection type liquid crystal display of the prior art includes a diffuser plate for diffuse reflection of external light, productivity is reduced due to an increase in the volume and manufacturing cost of the diffuser plate.

Second, in the conventional reflective liquid crystal display device, when the symmetrical fit is formed on the pixel electrode of the lower substrate, the luminance is lowered due to spatial constraints for forming the fit.

Third, the reflective liquid crystal display of the prior art has low light efficiency because the reflective electrode cannot be condensed in the direction of the user when the reflective electrode is formed to have symmetrical irregularities to diffuse the incident external light.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and an object thereof is to provide a reflective liquid crystal display device having high directivity and a manufacturing method thereof by forming asymmetric unevenness on the surface of the reflective electrode.

1 is a schematic perspective view of a general transmissive liquid crystal display device.

2 is a schematic perspective view of a general reflective liquid crystal display device.

3 is a plan view of a conventional general reflective liquid crystal display device.

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

5 is a plan view of another conventional reflective liquid crystal display device.

FIG. 6 is a cross-sectional view taken along line II ′ of FIG. 5.

7 is a plan view of another conventional reflective liquid crystal display device.

FIG. 8 is a cross-sectional view taken along line III-III ′ of FIG. 7.

9 is a view schematically showing reflection of incident light in a conventional reflective electrode having symmetrical irregularities.

10 to 11 are plan views of reflective liquid crystal display devices according to the first to second embodiments of the present invention.

FIG. 12 is a cross-sectional view of the lower substrate of FIGS.

FIG. 13 is a view showing that incident light is reflected on the surface of the reflective electrode of the present invention having asymmetric unevenness.

14 to 21 are cross-sectional views of manufacturing a reflective liquid crystal display device according to the present invention.

FIG. 22 is a cross-sectional view illustrating a halftone mask used in a process of manufacturing a reflective liquid crystal display device according to a first embodiment of the present invention.

FIG. 23 is a graph showing the transmittance of the mask according to FIG. 22.

FIG. 24 is a cross-sectional view illustrating a halftone mask used in a process of manufacturing a reflective liquid crystal display device according to a second embodiment of the present invention.

FIG. 25 is a diagram illustrating diffraction phenomenon in a diffraction mask in which the size of the fine protrusions increases in sequence.

FIG. 26 is a diagram illustrating diffraction phenomenon in a diffraction mask in which the spacing of minute protrusions increases in sequence.

27 is a graph showing the transmittance of the mask according to FIG. 24.

FIG. 28 is a cross-sectional view illustrating a gray mask used in a process of manufacturing a reflective liquid crystal display device according to a third embodiment of the present invention.

29 is a graph showing the transmittance of the mask according to FIG. 28.

Explanation of symbols for main parts of the drawings

60: lower substrate 61: gate wiring

62: data wiring 63: reflective electrode

64: asymmetric unevenness 65: gate electrode

66 gate insulating film 67 semiconductor layer

68a, 68b: source / drain electrodes 69: protective film

71a: first alignment layer 72: halftone mask

73: ultraviolet ray 80: opaque substance

81: translucent material film 82,83: material film with low transmittance

84: micro projection 85: light absorbing material

92: diffraction mask 93: gray mask

100: incident light 101: reflected light

102: eyes

A reflective liquid crystal display device of the present invention for achieving the above object includes a gate wiring and a data wiring formed vertically and horizontally to define a pixel region, a reflective electrode formed on the pixel region with a plurality of asymmetrical irregularities, and And a thin film transistor formed at the intersection of the gate wiring and the data wiring.

Here, the asymmetric unevenness has different inclinations on both sides with respect to the tip.

The plurality of asymmetric unevennesses have a gentle slope in one direction.

In addition, a gate wiring formed in one direction on the lower substrate and a gate electrode protruding from the gate wiring, a gate insulating film formed on a substrate including the gate wiring, a semiconductor layer formed on the gate insulating film above the gate electrode, Source electrodes, drain electrodes, and data lines formed on both sides of the semiconductor layer, a protective film formed on the drain electrode to have a plurality of asymmetric unevennesses on an upper surface thereof, and an asymmetric unevenness shape on the pixel region. It is characterized by including a reflective electrode.

Here, the protective film uses a photosensitive material to form asymmetric unevenness by photolithography.

In addition, the method of manufacturing a reflective liquid crystal display device of the present invention comprises the steps of forming a thin film transistor at the intersection of the gate wiring and data wiring, forming a protective film on the substrate on which the thin film transistor is formed, Forming a contact hole in the drain electrode and forming a plurality of asymmetric unevennesses; and forming a reflective electrode on the passivation layer to be connected to the drain electrode.

Here, the asymmetric unevenness is made through a photolithography method using a halftone mask.

Ashing is further performed on the asymmetric unevenness of the protective film.

In the reflective liquid crystal display of the present invention, a plurality of asymmetric unevennesses having a gentle inclination in one direction are formed on the surface of the reflective electrode in order to increase the directivity of the reflected light.

That is, the reflective liquid crystal display of the present invention is patterned so that asymmetrical irregularities having a gentle inclination in one direction are formed on the upper surface of the protective layer by using a mask having an inclination of a portion corresponding to one unevenness, and the protective layer Directivity may be enhanced by depositing a conductive metal material having excellent reflectivity on the pattern and then patterning the reflective electrode.

Hereinafter, a reflective liquid crystal display and a method of manufacturing the same will be described with reference to the accompanying drawings.

10 is a plan view of a reflective liquid crystal display device according to a first embodiment of the present invention.

As shown in FIG. 10, the liquid crystal display according to the first exemplary embodiment of the present invention has a gate wiring 61 and a data wiring 62 formed vertically and horizontally to define a pixel region, the gate wiring 61 and A reflective electrode having a thin film transistor T formed at a portion where the data lines 62 intersect, and an asymmetric unevenness 64 for applying a data signal and reflecting external light in one direction due to the switching of the thin film transistor T. It comprises a 63.

Although not shown, the asymmetric unevenness 64 is formed along the asymmetric unevenness formed on the surface of the protective film formed under the reflective electrode 63.

Here, " A " is a partial perspective view of FIG. 10, wherein a gentle inclined surface is formed in one direction so as to reflect external light incident to the asymmetric unevenness 64 to have directivity to the user, whereas The other direction is formed to have a steep slope.

In addition, although a plurality of the asymmetrical irregularities 64 having a gentle slope in one direction are arranged in a line in the vertical direction, as shown in FIG. 11, they may be spaced apart at regular intervals, or randomly. It may be formed.

Looking at the cross section of the lower substrate of the reflective LCD according to the present invention as follows.

FIG. 12 is a cross-sectional view of the lower substrate taken along line IV to IV ′ of FIG. 10.

As shown in FIG. 12, the reflective LCD according to the present invention includes a gate electrode 65 formed to protrude from the gate wiring 61 formed in one direction on the lower substrate 60, and an upper portion of the gate electrode 65. A gate insulating film 66 formed on the gate insulating film 66, an island-shaped semiconductor layer 67 formed on the gate insulating film 65 corresponding to the gate electrode 65, and source / drain electrodes 68a formed on both sides of the semiconductor layer. 68b, a protective film 69 formed on the substrate including the drain electrode 68b, and a reflective electrode electrically connected to the drain electrode 68b and formed of a highly reflective metal material on the protective film 69. And the alignment film 71a formed on the reflective electrode 63.

In this case, the passivation layer 69 is formed of a photosensitive layer, and asymmetric unevenness 64 is formed on the upper surface of the passivation layer 69.

In addition, the reflective electrode 63 is formed in the same shape along the asymmetric unevenness 64 formed on the upper surface of the protective film 69.

On the other hand, indoors, a light source such as an incandescent lamp or a fluorescent lamp is disposed on the ceiling, or a light source such as sunlight enters through a window. As such, the light source is generally located above the liquid crystal display. In addition, the light source is mainly located above the liquid crystal display device outdoors.

Therefore, in order to efficiently use the light irradiated from such a light source, the reflection angle of the reflection type liquid crystal display device can be directed to direct the reflected light toward the user, thereby improving the light efficiency of the reflection type liquid crystal display device.

FIG. 13 is a view illustrating incident light reflected on a surface of a reflector having asymmetric unevenness. The incident light 100 incident in parallel from a light source (not shown) is formed through the asymmetric unevenness formed on the surface of the reflective electrode 63. It can be seen that the reflected reflected light 101 is directed in the direction of the user's eye 102.

Therefore, the parallel light emitted from the light source to the liquid crystal display can be reflected in one direction through the asymmetric unevenness 64 formed on the surface of the reflective electrode 63.

Therefore, the reflective liquid crystal display device of the present invention can increase the light efficiency by using the asymmetric unevenness 64 formed on the surface of the reflective electrode 63.

The manufacturing method of the reflective liquid crystal display device according to the present invention configured as described above is as follows.

14 to 20 are cross-sectional views of a reflective liquid crystal display device according to the present invention.

First, as shown in FIG. 14, a conductive material such as Al, Mo, Ta, W, Cr, or Al alloy is formed on the lower substrate 60, and then the gate wiring 61 in one direction using a photolithography process. ), And at the same time, the gate electrode 65 is formed to protrude from the gate wiring 61.

Next, as shown in FIG. 15, SiN _X , SiO _X , and the like are deposited on the entire surface of the lower substrate 60 including the gate electrode 65 by plasma chemical vapor deposition (CVD). ).

Subsequently, as shown in FIG. 16, after the a-Si thin film is deposited on the lower substrate 60 including the gate insulating layer 66 by the plasma CVD method, the gate corresponding to the gate electrode 65 is formed. The semiconductor layer 67 is formed by patterning only the a-Si thin film on the insulating film 66.

Then, as shown in Figure 17, after forming a metal, such as Al, Cr, Ti, Al alloy on the entire surface of the lower substrate 60 including the semiconductor layer 67 by a sputtering method, a photolithography The data line 62 is formed to intersect the gate line 61 using the process, and the source / drain electrodes 68a and 68b are formed on both sides of the semiconductor layer 67 at the same time.

18 to 20, a protective film 69 made of a photosensitive material is formed on the lower substrate 60 on which the data line 62 is formed, and a predetermined portion of the drain electrode 68b is formed. The protective film 69 is exposed, and a plurality of asymmetric unevenness 64 is formed on the upper surface of the protective film 69.

At this time, after forming the asymmetric unevenness 64 on the upper surface of the protective film 69, a portion of the protective film 69 corresponding to the drain electrode 68b may be exposed.

Next, as shown in FIG. 21, the reflective electrode 63 is formed on the protective film 69 on which the asymmetric unevenness 64 is formed to have the shape of the asymmetric unevenness 64 by using a conductive metal having excellent reflectivity such as Al. To form.

Although not shown, a first alignment layer 71a is formed on the lower substrate on which the reflective electrode 63 is formed, and the thin film transistor T, the gate wiring 61 and the data wiring 62 are formed on the upper substrate. A black matrix is formed to shield the light, a color filter is formed on the upper substrate on which the black matrix is formed, and a second alignment layer is formed on the upper substrate on which the color filter is formed.

Finally, the lower substrate 60 and the upper substrate are bonded together, and a liquid crystal layer (not shown) is formed between the two substrates, thereby completing the manufacturing process of the reflective liquid crystal display device according to the present invention.

In the manufacturing process of such a reflective liquid crystal display device, in order to form a plurality of thin films can be generally formed using a photolithography method.

In particular, the following photolithography process may be performed to form the asymmetric unevenness 64 on the upper surface of the protective film 69 formed of the photosensitive material.

20 is a detailed cross-sectional view of a manufacturing process of a liquid crystal display according to the present invention, in which one asymmetric unevenness (64 in FIG. 10) is formed to form a plurality of asymmetric unevennesses (64 in FIG. 10) on an upper surface of a protective film 69 made of a photosensitive film. 64 shows a photolithography process using a half tone mask 72 in which the transmittance is changed in one direction.

In this case, the light transmitted by the halftone mask 72 may be used as a light source having a specific wavelength such as ultraviolet rays 73.

In addition, the characteristic of the photosensitive film is positive, and the portion exposed to the ultraviolet light (Ultra Violet) 73 irradiated from the light source is developed or etched.

Therefore, in the liquid crystal display of the present invention, the asymmetric unevenness 64 may be formed through a photolithography method using a mask having a transmittance inclined in one direction on a portion where one unevenness is to be formed.

Such a method of manufacturing the reflective liquid crystal display device of the present invention will be described in detail with reference to Examples.

FIG. 22 is a cross-sectional view illustrating a halftone mask used in a process of manufacturing a reflective liquid crystal display device according to a first embodiment of the present invention.

As shown in FIG. 22, the half tone mask 72 used in the reflective liquid crystal display manufacturing process according to the first embodiment of the present invention is provided at a portion corresponding to one asymmetric unevenness 64. FIG. Since the translucent materials 81, 82, and 83 are sequentially stacked to transmit the gradient in one direction, the half surface of the protective film 69 is half-exposed using the half-tone mask 72 such that the symmetrical irregularities 64 are formed. Can be formed.

Here, such a translucent material may have a stacked structure to have 2 to 4 layers as shown in the figure.

For example, the half tone mask 72 is formed of chromium (Cr) and chromium (Cr) to block ultraviolet rays (73 in FIG. 22) at a portion corresponding to the tip 64a of the asymmetric unevenness 64 formed on the upper surface of the protective film 69. The same opaque material 80 is formed, and a silicide-based first semi-transmissive film 81 is formed between the opaque material 80 and the opaque material 80, and is close to the opaque material 80. On one side of the transflective layer, a second material layer 82 such as silicon (Si), silicon nitride (SiNx), silicon oxide (SiOx), or the like is formed. Similarly, another third semi-permeable membrane 83 may be further formed on one side of the material having a low transmittance.

FIG. 23 is a view showing the transmittance of the mask according to FIG. 22, from the state of low transmittance from the opaque material 80 to the transflective layers 81, 82, 83 and the transmission region (not shown). It can be seen that the transmittance is sequentially increased in the step shape.

That is, by adjusting the amount of light transmitted through the half-tone mask in which the semi-transmissive film 81 and the low transmissive material film 82 are sequentially stacked, a part of the upper surface of the protective film 69 formed of the photosensitive material The asymmetric unevenness 64 may be formed by developing the upper surface of the passivation layer 69 that is differentially exposed and the differential exposure.

In addition, when the protective film 69 is patterned, the tip 64a of the steep inclined surface 64 of the asymmetric unevenness 64 is smoothed through ashing after the development to be formed on the protective film 69. The formation of the reflective electrode 63 may be facilitated.

24 is a cross-sectional view illustrating a mask used in a process of manufacturing a reflective liquid crystal display device according to a second embodiment of the present invention.

As shown in FIG. 24, the diffraction mask 92 used in the reflective liquid crystal display manufacturing process according to the second exemplary embodiment of the present invention is provided with minute projections 84 having different sizes in portions corresponding to one unevenness. Forming large in sequence can vary the intensity of light transmitted due to diffraction of light. The asymmetric unevenness 64 can be formed by diffraction exposure on the upper surface of the protective film 69 using such a diffraction mask 92.

Here, the smaller the distance between the micro-projections 84 can produce more diffraction phenomenon, the smaller the size of the micro-projections 84 can cause more diffraction phenomenon, the diffraction phenomenon occurs a lot In this case the light intensity is further reduced.

In other words, the size of the micro-projections 84 may be increased in order to reduce the diffraction phenomenon, or the distance between the plurality of micro-projections 84 may be increased in order to reduce the diffraction phenomenon, thereby changing the intensity of transmitted light and thereby asymmetry. Unevenness 64 can be formed.

FIG. 25 is a diagram illustrating a diffraction phenomenon in a diffraction mask in which the size of the micro-projections increases in sequence. In the light passing through the plurality of micro-projections 84 having different sizes, the wavefront of the same phase spreads out in a circular model. It can be seen that the wavefronts interfere with each other to change the intensity of light.

Here, referring to the Young's diffraction experiment, the smaller the size of the slit is, the wider the gap of the diffraction pattern appears, and the smaller the exposure is. Therefore, the slit may correspond to the minute protrusions 84 and thus is subjected to diffraction exposure.

FIG. 26 shows a diffraction phenomenon in a diffraction mask in which the spacing of the fine protrusions is sequentially increased. As the spacing between the plurality of minute protrusions having a constant size increases, the diffraction phenomenon decreases and the space between the minute protrusions 84 is increased. The light passing through it can be seen that proceeds as is.

Therefore, the diffraction mask 92 used in the reflective liquid crystal display manufacturing process of the present invention can be provided with a plurality of minute projections 84 having different sizes or spacing therebetween to facilitate formation of asymmetric unevenness.

In this case, in order to control the intensity of light using a diffraction phenomenon, the size of the minute protrusions 84 is several to several tens of micrometers (μm), and the material of the minute protrusions 84 is made of light absorbing black. This is preferred.

FIG. 27 is a graph illustrating the transmittance of the mask according to FIG. 24. As the size of the micro-projections increases from the opaque material 80, it can be seen that the transmittance increases in a parabolic shape with distance from a low transmittance.

By adjusting the amount of light transmitted using a mask in which a plurality of minute protrusions 84 having a predetermined size and interval are formed, a part of the upper surface of the protective film 89 formed of the photosensitive material is differentially exposed and the differential exposure is performed. An asymmetric unevenness 64 may be formed by developing the upper surface of the passivation layer 84.

FIG. 28 is a cross-sectional view illustrating a gray mask used in a process of manufacturing a reflective liquid crystal display device according to a third embodiment of the present invention.

As shown in FIG. 28, the gray mask 72 used in the reflective liquid crystal display manufacturing process according to the third exemplary embodiment of the present invention has a transmittance inclined in one direction to a portion corresponding to one unevenness. The light absorbing material 85 may be formed to have a different intensity of transmitted light. Therefore, asymmetrical unevenness 64 can be formed by patterning the upper surface of the protective film using such a gray mask.

Here, the mask 72 may vary the concentration of the light absorbing material 85 so that the transmittance is inclined in one direction to a portion corresponding to the unevenness, as shown in FIG. The thickness can be varied.

FIG. 29 is a graph showing the transmittance of the mask according to FIG. 28, and has a constant slope with distance from the state of low transmittance as the size increases from the opaque material 80 to the light absorbing material 85. It can be seen that the increase.

Similarly, by adjusting the amount of light transmitted using the mask 72 having the light absorbing material 85 having a constant transmittance, the upper surface of the protective film 69 formed of the photosensitive material is differentially exposed, and the differential exposure. An asymmetric unevenness 64 may be formed by developing the upper surface of the passivation layer 69.

As described above, in the method of manufacturing a reflective liquid crystal display device of the present invention, a protective film 69 is formed using a photosensitive material, and a transmittance corresponding to one unevenness on the upper surface of the protective film 69 is in one direction. The light efficiency can be improved by forming a plurality of asymmetric unevenness 64 using the halftone mask 72, the diffraction mask 92, or the gray mask 93 having the inclination.

As described above, the reflective liquid crystal display of the present invention and the manufacturing method thereof have the following effects.

First, the reflective liquid crystal display device of the present invention has an asymmetric uneven surface formed with a gentle inclined surface on the surface of the reflective electrode, thereby condensing the light emitted from the light source in the direction of the observer can increase the light efficiency.

Second, the method of manufacturing a reflective liquid crystal display device of the present invention is asymmetric because a mask having a transmittance gradient is used to form a plurality of asymmetric unevennesses on the upper surface of the protective film formed of the photosensitive material. Formation of unevenness can be easily formed.

Claims (19)

Gate wiring and data wiring formed vertically and horizontally to define the pixel region; A reflective electrode having a plurality of asymmetric unevennesses formed on the pixel area; And a thin film transistor formed at an intersection point of the gate line and the data line. The reflective liquid crystal display device according to claim 1, wherein the asymmetric unevenness has different inclinations on both sides of the tip. The reflective liquid crystal display device according to claim 1, wherein the plurality of asymmetric unevennesses have a gentle inclined surface in one direction. A gate wiring formed in one direction on the lower substrate and a gate electrode protruding from the gate wiring; A gate insulating film formed on a substrate including the gate wiring; A semiconductor layer formed on the gate insulating film above the gate electrode; Source electrodes, drain electrodes, and data lines formed on both sides of the semiconductor layer; A protective film formed on the drain electrode to have a plurality of asymmetric unevennesses on an upper surface thereof; And a reflective electrode having an asymmetric uneven shape on the pixel area. The liquid crystal display of claim 4, wherein the passivation layer is formed of a photosensitive material. Forming a thin film transistor at an intersection of the gate wiring and the data wiring; Forming a protective film on the substrate on which the thin film transistor is formed; Forming a contact hole in the drain electrode of the thin film transistor and forming a plurality of asymmetric unevennesses; And forming a reflective electrode on the passivation layer so as to be connected to the drain electrode. The method of claim 6, wherein the asymmetric unevenness is formed by a photolithography method using a halftone mask. The method of claim 7, wherein the halftone mask is formed by stacking semitransmissive layers on portions corresponding to one asymmetric unevenness. The method of claim 8, wherein the half-tone mask further comprises an opaque material formed on one side of the semi-transmissive layers. 9. The method of claim 8, wherein the transmittance of the halftone mask has a step shape. The method of claim 6, wherein the asymmetric unevenness is formed by a photolithography method using a diffraction mask. 12. The method of claim 11, wherein the diffraction mask has a plurality of minute protrusions having sequential sizes in portions corresponding to the asymmetric unevenness. 12. The method of claim 11, wherein the diffraction mask is formed such that a distance between the plurality of minute protrusions having a predetermined size is increased in one direction. The method of claim 12, wherein the diffraction mask further comprises an opaque material formed on one side of the micro-projection. The method of manufacturing a reflective liquid crystal display device according to any one of claims 12 and 13, wherein the plurality of minute protrusions are black light absorbing materials. The method of manufacturing a reflective liquid crystal display device according to any one of claims 12 to 13, wherein the transmittance of the diffraction mask has a parabolic shape. The method of claim 6, wherein the asymmetric unevenness is formed by a photolithography method using a gray mask. 18. The method of claim 17, wherein the gray mask has a light absorbing material having a transmittance inclined in one direction on a portion corresponding to the asymmetric unevenness. 7. The method of claim 6, further comprising ashing the asymmetric unevenness of the passivation layer.