KR20040039988A - Liquid crystal display and method for manufacturing the same - Google Patents

Abstract

PURPOSE: A liquid crystal display and a manufacturing method thereof are provided to maintain a cell gap constantly and prevent the light leakage phenomenon from generating, and enhance a contrast ratio, thereby enhancing a display characteristic. CONSTITUTION: A TFT(Thin Film Transistor) substrate(500) is a substrate in which a unit pixel is formed by a matrix shape, and comprises a TFT(520) formed on a glass substrate, an organic insulation film(530) formed on a first substrate(510) including the TFT(520), and pixel electrodes(540,550) formed on the organic insulation film(530). Between the TFT(520) and the pixel electrodes(540,550), the organic insulation film(530) is interposed. A plurality of protrusion and depression members(533) having a first height are formed on the surface of the organic insulation film(530).

Description

Liquid crystal display and its manufacturing method {LIQUID CRYSTAL DISPLAY AND METHOD FOR MANUFACTURING THE SAME}

The present invention relates to a liquid crystal display device and a manufacturing method thereof, and more particularly, to a liquid crystal display device and a method for manufacturing the same that can improve the display characteristics.

In today's information society, the role of display devices becomes more and more important, and various display devices are widely used in various industrial fields. BACKGROUND With the rapid advance of semiconductor technology, liquid crystal display devices having thin and light display devices and low power consumption are widely used in accordance with the miniaturization and light weight of various information processing devices.

Recently, a reflection-transmissive liquid crystal display device utilizing both the advantages of a reflective liquid crystal display device and a transmissive liquid crystal display device has been developed in order to realize high quality images while reducing power consumption. Such a reflection-transmissive liquid crystal display displays an image in a reflection mode using the first light in a place where the external light amount is abundant, and uses a second light generated by consuming electric energy charged in itself when the external light amount is insufficient. Displays the image in the transmission mode used.

Recently, the reflection-transmissive liquid crystal display has been developed with a structure suitable for improving the image quality in the reflection mode. Typical reflection-transmissive liquid crystal display devices meeting this trend are as follows.

1 is a cross-sectional view of a typical reflection-transmissive liquid crystal display device.

Referring to FIG. 1, a general reflection-transmissive liquid crystal display device 400 may include a thin film transistor (TFT) substrate 100 and a color filter substrate 200 facing the TFT substrate 100. And a liquid crystal layer 300 injected between the TFT substrate 100 and the color filter substrate 200.

The TFT substrate 100 is formed on the glass substrate 110 by the TFT 120, the pixel electrodes 140 and 150 connected to the TFT 120, and the TFT 120 and the pixel electrodes 140 and 150. It is a board | substrate with which the organic insulating film 130 interposed was formed.

The pixel electrodes 140 and 150 include the reflective electrode 150 and the transparent electrode 140 at the same time. The reflective electrode 150 is formed with a transmission window 151 exposing the transparent electrode 140.

Accordingly, the reflection-transmissive liquid crystal display 400 operates in a reflection mode in which the first light incident through the color filter substrate 200 is reflected through the reflection electrode 150 to display an image. In addition, the second light incident from the light source unit (not shown) disposed on the rear surface of the TFT substrate 100 is transmitted through the transmission window 151 to operate in a transmission mode for displaying an image.

In this case, the reflective electrode 150 is formed to have a concave-convex structure in order to improve the viewing angle of the reflective-transmissive liquid crystal display device 400 while increasing the amount of reflection of the reflective electrode 150. Since the reflective electrode 150 is stacked on the organic insulating layer 130 with a uniform thickness, the reflective electrode 150 is determined by the surface structure of the organic insulating layer 130. Accordingly, a plurality of irregularities 133 are formed on the surface of the organic insulating layer 130 so that the reflective electrode 150 has an uneven structure. The unevenness 133 includes a convex portion 133a and a concave portion 133b having relative heights.

This structure is excellent in terms of improving the viewing angle of the reflection-transmissive liquid crystal display device 400. However, by forming the uneven structure on the surface of the TFT substrate 100, the separation distance between the TFT substrate 100 and the color filter substrate 200 is not uniform. That is, such a structure may also act as a cause of non-uniformity of the cell gap of the reflection-transmissive liquid crystal display device 400.

As such, when the cell gap becomes non-uniform, light leakage occurs in the reflection-transmissive liquid crystal display 400, thereby deteriorating display characteristics and causing a problem in which a contrast ratio (C / R) is reduced. .

Therefore, in the case where the unevenness is formed on the surface of the TFT substrate 100, there is a need for a structural method that can uniformly maintain the cell gap of the reflection-transmissive liquid crystal display device 400.

Accordingly, it is a first object of the present invention to provide a liquid crystal display device for improving display characteristics.

In addition, a second object of the present invention is to provide a method of manufacturing the above-mentioned liquid crystal display device.

1 is a cross-sectional view illustrating a general reflection-transmissive liquid crystal display device.

2 is a cross-sectional view illustrating a reflection-transmissive liquid crystal display device according to an exemplary embodiment of the present invention.

3A to 3E are cross-sectional views illustrating a manufacturing process of the reflection-transmissive liquid crystal display shown in FIG. 2.

4 is a cross-sectional view illustrating a reflection-transmissive liquid crystal display device according to another exemplary embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

500: TFT substrate 520: TFT

530: organic insulating film 540: transparent electrode

550: reflective electrode 600: color filter substrate

620: light shielding film 630, 660: color filter

640: protective film 650, 670: common electrode

700: liquid crystal layer 800, 900: reflection-transmissive liquid crystal display device

According to an aspect of the present invention, there is provided a liquid crystal display device including: a first substrate having a plurality of first uneven portions formed of a first convex portion and a first concave portion on a first surface; On the second surface facing the first surface, a plurality of second unevenness formed of a second convex portion corresponding to the first concave portion and a second concave portion corresponding to the first convex portion is formed. A second substrate which maintains a constant distance between the second surface and the second surface; And a liquid crystal layer interposed between the first and second substrates.

In addition, the manufacturing method of the liquid crystal display device according to the present invention for achieving the second object of the present invention, manufacturing a first substrate having a plurality of first unevenness consisting of the first convex portion and the first concave portion on the first surface Making; The second surface facing the first surface is formed with a plurality of second unevenness consisting of a second convex portion corresponding to the first concave portion and a second concave portion corresponding to the first convex portion, Manufacturing a second substrate to maintain a constant distance between the second surface and the second surface; Combining the first and second substrates; And forming a liquid crystal layer between the first and second substrates.

According to such a liquid crystal display and a manufacturing method thereof, the first substrate has a plurality of first uneven portions formed by the first convex portion and the first concave portion, and the second substrate has the second convex portion corresponding to the first concave portion. And a plurality of second concave-convex portions formed of a second concave portion corresponding to the first convex portion. Therefore, the cell gap of the liquid crystal display device can be maintained uniformly to improve display characteristics.

Hereinafter, with reference to the accompanying drawings, it will be described in detail a preferred embodiment of the present invention.

2 is a cross-sectional view illustrating a reflection-transmissive liquid crystal display device according to an exemplary embodiment of the present invention.

Referring to FIG. 2, the reflective-transmissive liquid crystal display device 800 according to the exemplary embodiment of the present invention includes a TFT substrate 500, a color filter substrate 600 and the TFT facing the TFT substrate 500. The liquid crystal layer 700 is injected between the substrate 500 and the color filter substrate 600.

The TFT substrate 500 includes a TFT 520 on the first glass substrate 510, an organic insulating layer 530, and the organic insulating layer 530 formed on the first substrate 510 including the TFT 520. The unit pixel formed of the pixel electrodes 540 and 550 formed on the substrate is formed in a matrix form.

The TFT 520 has a gate electrode 521, a source electrode 525, and a drain electrode 526. In this case, the gate electrode 521 is insulated from the source electrode 525 and the drain electrode 526 through a gate insulating film. As power is applied to the gate electrode 521, an active pattern and an ohmic contact pattern for applying power from the source electrode 525 to the drain electrode 526 are formed on the gate insulating layer. Source and drain electrodes 525 and 526 are formed thereon.

In this case, the organic insulating layer 530 is interposed between the TFT 520 and the pixel electrodes 540 and 550. A contact hole 531 is formed in the organic insulating layer 530 to expose the drain electrode 526. The drain electrode 526 and the pixel electrodes 540 and 550 are electrically connected through the contact hole 531.

A plurality of first unevennesses 533 having a first height is formed on the surface of the organic insulating layer 530. The first unevenness 533 may have a first convex portion 533a having a relatively high height from the first glass substrate 510 and a first concave portion 533b having a relatively low height from the first glass substrate 510. ). The first height is defined as a vertex of the first convex portion 533a and a vertical distance of the first concave portion 533b.

Subsequently, the pixel electrodes 540 and 550 are coated with a uniform thickness on the drain electrode 526 exposed by the organic insulating layer 530 and the contact hole 531. The pixel electrodes 540 and 550 include a transparent electrode 540 and a reflective electrode 550. Specifically, the transparent electrode 540 made of indium tin oxide (ITO) or indium zinc oxide (IZO) is uniformly disposed on the organic insulating layer 530 and the contact hole 531. Laminated to one thickness. Thus, the transparent electrode 540 has the same surface structure as the organic insulating layer 530.

Next, the reflective electrode 550 made of aluminum (Al) having excellent reflectance is stacked on the transparent electrode 540 with a uniform thickness. The reflective electrode 550 is formed with a transmission window 551 exposing a portion of the transparent electrode 540.

In this case, the reflective region is an area where the reflective electrode 550 is formed, and the transmission area is an area defined by the transmission window 551.

The reflection-transmissive liquid crystal display 800 is a reflection mode in which an image is displayed by light reflected by the reflective electrode 550 and a transmission mode in which an image is displayed by light passing through the transmission window 551. Can be operated. When operating in the reflective mode, the reflective electrode 550 is formed in a concave-convex structure so that not only the light efficiency is increased, but the reflective-transmissive liquid crystal display 800 can secure a wide viewing angle.

Although not shown, a first alignment layer (not shown) is further formed on the reflective electrode 550 and the transmission window 551. Specifically, the first alignment layer is formed by coating an organic film of a polyimide system on the reflective electrode 550 and the transmission window 551 and then rubbing in a predetermined direction.

The color filter substrate 600 is a substrate on which the light blocking film 620, the color filter 630, the protective film 640, and the common electrode 650 are sequentially formed on the second glass substrate 610.

Specifically, the light blocking film 620 is formed to correspond to an ineffective display area of the TFT substrate 500. As shown in the figure, the light blocking film 620 is formed corresponding to a region where the TFT 520 is formed to prevent the TFT 520 from being projected on the screen of the reflection-transmissive liquid crystal display device 800. . In addition, the light blocking film 620 blocks the light leaked from the color filter 630 to improve the contrast rate of the reflection-transmissive liquid crystal display device 800.

The color filter 630 includes an R (Red) color pixel expressed in red by light, G (Green) expressed in green by light, and B (Blue) color expressed in blue by light. Each of the color pixels partially overlaps the light blocking film 620 and is formed on the second glass substrate 610 on which the light blocking film 620 is not formed. In this case, since each of the color pixels has a different color, the respective color pixels are spaced apart from adjacent color pixels at predetermined intervals on the light blocking film 620.

As illustrated, a passivation layer 640 is formed on the color filter 630 and the light blocking layer 620. The passivation layer 640 protects the color filter 630 and removes a step formed between the color filter 630 and the light blocking layer 620.

In addition, a plurality of second unevenness 643 having a second height is formed on the surface of the passivation layer 640. The second unevenness 643 may include a second convex portion 643b having a relatively high height from the second glass substrate 610 and a second concave portion having a relatively low height from the second glass substrate 610. 643a. The second height is defined as a vertical distance between a vertex of the second convex portion 643b and a vertex of the second concave portion 643a. Here, the second convex portion 643b is formed at a position corresponding to the first concave portion 533b formed on the organic insulating layer 630 of the TFT substrate 500. In addition, the second concave portion 643a is formed at a position corresponding to the first convex portion 533a.

The second height of the second unevenness 643 is preferably the same as the first height of the first unevenness 533 formed in the organic insulating layer 530.

Next, the common electrode 650 is formed on the passivation layer 640 to have a uniform thickness. The common electrode 640 is made of a transparent conductive film such as an ITO or IZO film. Although not illustrated, a second alignment layer is formed on the common electrode 640, and the second alignment layer together with the first alignment layer controls the pretilt angle of the liquid crystal layer 700.

The color filter substrate 600 is coupled to face the TFT substrate 500 such that the common electrode 650 faces the pixel electrodes 540 and 550. As such, when the color filter substrate 600 and the TFT substrate 500 are coupled to face each other, a liquid crystal layer 470 is formed between the color filter substrate 600 and the TFT substrate 500. Thus, the reflection-transmissive liquid crystal display device 800 is completed.

As shown, the reflective-transmissive liquid crystal display 800 has the same cell gap at some locations. Here, the cell gap is defined as the separation distance between the TFT substrate 500 and the color filter substrate 600.

Specifically, the reflection-transmissive liquid crystal display device 800 has a first cell gap d1 between the first convex portion 533a and the second concave portion 643a, and the first concave portion 533b. ) And the second convex portion 643b has a second cell gap d2. Assuming that the second height is the same as the first height, the first and second cell gaps d1 and d2 are also the same. Even if the first and second heights are not exactly the same, deviations of the first and second cell gaps d1 and d2 may be reduced than when the passivation layer 640 has a flat surface structure. As a result, the cell gap of the reflection-transmissive liquid crystal display device 800 can be maintained uniformly.

3A to 3E are cross-sectional views illustrating a manufacturing process of the reflection-transmissive liquid crystal display shown in FIG. 2.

Referring to FIG. 3A, a light blocking film 620 is formed on the second glass substrate 610. The light shielding film 620 is formed corresponding to the ineffective display area of the TFT substrate 500. Chromium oxide (CrO ₂ ) or an organic black matrix (B / M) having a low reflectance is used for the light blocking film 620.

A first photoresist (not shown) including a red dye or a red pigment is coated on the second glass substrate 610 on which the light blocking film 620 is formed to have a uniform thickness. Thereafter, the first photoresist is patterned to form an R color pattern. Next, after forming a second photoresist (not shown) including a green dye and a green pigment on the second glass substrate 610, the second photoresist is patterned to form a G color pixel pattern. Next, after forming a third photoresist (not shown) including a blue dye and a blue pigment on the second glass substrate 610, the third photoresist is patterned to form a B pixel pattern.

Each of the color pixel patterns is spaced apart from the adjacent color pixel pattern on the light blocking film 620 by a predetermined interval. As a result, a color filter 630 including R, G, and B color pixels is completed on the second glass substrate 610.

3B, a protective material 645 made of acrylic resin or polyimide resin, which is one of photosensitive organic insulating layers, on the second glass substrate 610 on which the color filter 630 and the light blocking film 620 are formed. Is applied.

Referring next to FIG. 3C, a mask 647 is disposed on the protective material 645. A pattern corresponding to the second unevenness 643 is formed in the mask 647. Thereafter, when the protective material 645 is exposed after the mask 647 is disposed, and the exposed protective material 645 is developed, the second unevenness 643 is formed on the second glass substrate 610. A protective film 640 is formed.

The second unevenness 643 may have a second convex portion 643b having a relatively high height from the second glass substrate 610 and a second concave portion having a relatively low height from the second glass substrate 610. 643a.

Although not shown in the drawing, the mask 147 has a phase opposite to that of the pattern mask used for patching the organic insulating film 530 formed on the TFT substrate 500. That is, an area that transmits light in the mask 147 corresponds to an area that blocks light in the pattern mask, and an area that blocks light in the mask 147 corresponds to an area that transmits light in the pattern mask. do.

As shown in FIG. 3D, the common electrode 650 is stacked on the passivation layer 640 with a uniform thickness. As a result, the color filter substrate 600 whose height from the second glass substrate 610 is not uniform is completed.

Thereafter, referring to FIG. 3E, the completed color filter substrate 600 is coupled to the TFT substrate 500 such that the common electrode 650 faces the pixel electrodes 540 and 550. As described above, the first unevenness 533 formed of the first convex portion 533a and the first concave portion 533b is formed on the organic insulating film 530 of the TFT substrate 500, and the organic insulating film 530 is formed. ), Pixel electrodes 540 and 550 are formed to have a uniform thickness.

When combined with the color filter substrate 600 and the TFT substrate 500, the first convex portion 533a corresponds to the second concave portion 643a, and the first concave portion 533b is formed on the first concave portion 533a. Corresponds to the two convex portions 643b. The color filter substrate 600 and the color filter substrate 600 are compensated for by the second concave portion 643a of the color filter substrate 600 by increasing the height of the TFT substrate 500 by the first convex portion 533a. The cell gap of the reflection-transmissive liquid crystal display device 800, which is a distance from the TFT substrate 500, may be kept constant. In addition, the first convex portion 643b of the color filter substrate 600 compensates for the height reduced by the first concave portion 533b of the TFT substrate 500, thereby providing the reflection-transmissive liquid crystal display device. The cell gap of 800 may be kept constant.

Referring back to FIG. 2, a liquid crystal layer 700 is interposed between the color filter substrate 600 and the TFT substrate 500 coupled thereto. As a result, the reflection-transmissive liquid crystal display device 800 capable of maintaining a uniform cell gap is completed.

4 is a cross-sectional view illustrating a reflection-transmissive liquid crystal display device according to another exemplary embodiment of the present invention. In FIG. 4, a reflection-transmissive liquid crystal display device is shown as another embodiment of the present invention in a case where a protective film is not provided between the color filter and the common electrode.

Referring to FIG. 4, the reflective-transmissive liquid crystal display device 900 according to another embodiment of the present invention includes a TFT substrate 500, a color filter substrate 600 provided opposite to the TFT substrate 500, and the TFT. The liquid crystal layer 700 is injected between the substrate 500 and the color filter substrate 600.

The color filter substrate 600 is a substrate on which the light blocking film 620, the color filter 660, and the common electrode 670 are sequentially formed on the second glass substrate 610.

Specifically, the light blocking film 620 is formed to correspond to an ineffective display area of the TFT substrate 500. As shown in the figure, the light blocking film 620 is formed corresponding to a region where the TFT 520 is formed to prevent the TFT 520 from being projected onto the screen of the reflection-transmissive liquid crystal display 900. . In addition, the light blocking film 620 blocks the light leaked from the color filter 660 to improve the contrast ratio of the reflective-transmissive liquid crystal display device 900.

The color filter 660 is composed of an R (Red) pixel expressed in red by light, G (Green) expressed in green by light, and B (Blue) pixel expressed in blue by light. Each of the color pixels partially overlaps the light blocking film 620 and is formed on the second glass substrate 610 on which the light blocking film 620 is not formed. Each of the color pixels is spaced apart from adjacent color pixels at predetermined intervals on the light blocking film.

A plurality of second unevenness 663 is formed on the surface of the color filter 660. The second unevenness 663 may include a second convex portion 663b having a relatively high height from the second glass substrate 610 and a second concave portion having a relatively low height from the second glass substrate 610. 663a. The second convex portion 663b is formed at a position corresponding to the first concave portion 533b of the first unevenness 533 formed in the organic insulating film 530 of the TFT substrate 500. The second concave portion 663a is formed at a position corresponding to the first convex portion 533a of the first unevenness 533.

The common electrode 670 is formed to have a uniform thickness on the color filter 660 and the light blocking film 620. The common electrode 670 is made of a transparent conductive film such as an ITO or IZO film.

The reflection-transmissive liquid crystal display 900 has a first cell gap d1 between the first convex portion 533a and the second concave portion 663a, and the first concave portion 533b and the The second cell gap d2 is provided between the second convex portions 663b. Assuming that the sizes of the first and second unevennesses 533 and 663 are the same, the first and second cell gaps d1 and d2 are also the same. In addition, even if the first and second heights are not exactly the same, the deviation of the first and second cell gaps d1 and d2 may be reduced than when the color filter 660 has a flat surface structure. As a result, the cell gap of the reflection-transmissive liquid crystal display device 900 can be maintained uniformly.

According to such a liquid crystal display and a manufacturing method thereof, the height increased by the first convex portion of the first substrate is compensated for by the second concave portion of the second substrate, and the height reduced by the first concave portion of the first substrate. Compensates for the first convex portion of the second substrate.

Therefore, the cell gap of the reflection-transmissive liquid crystal display device can be kept constant. Furthermore, the display characteristics of the reflection-transmissive liquid crystal display device can be improved by preventing light leakage and improving the contrast ratio.

In addition, in forming the concave-convex structure on the surface of the second substrate, it is easy to manufacture the reflection-transmissive liquid crystal display device by patterning the existing color filter or protective film.

Although described with reference to the embodiments above, those skilled in the art will understand that the present invention can be variously modified and changed without departing from the spirit and scope of the invention as set forth in the claims below. Could be.

Claims (5)

A first substrate having a plurality of first unevenness formed of a first convex portion and a first concave portion on a first surface thereof; On the second surface facing the first surface, a plurality of second unevenness formed of a second convex portion corresponding to the first concave portion and a second concave portion corresponding to the first convex portion is formed. A second substrate which maintains a constant distance between the second surface and the second surface; And And a liquid crystal layer interposed between the first and second substrates. The display device of claim 1, wherein the first substrate includes a switching element, a pixel electrode connected to the switching element, and an insulating layer interposed between the switching element and the pixel electrode and having the first unevenness formed on a surface thereof. The second substrate may include a color filter including R, G, and B pixels, a light shielding film interposed between the color pixels, a color formed on the color filter and the light shielding film, and a protective film on which the second unevenness is formed, and the protective film. And a common electrode formed to a thickness. The display device of claim 1, wherein the first substrate comprises a switching element, a pixel electrode connected to the switching element, and an insulating layer interposed between the switching element and the pixel electrode and having the first unevenness formed on a surface thereof. The second substrate is made of R, G, and B color pixels, and has a color filter in which the second unevenness is formed on a surface thereof, a light blocking film and a color filter interposed between the color pixels, and a common thickness formed on the light blocking film. And an electrode. Manufacturing a first substrate having a plurality of first unevenness formed of a first convex portion and a first concave portion on a first surface; The second surface facing the first surface is formed with a plurality of second unevenness consisting of a second convex portion corresponding to the first concave portion and a second concave portion corresponding to the first convex portion, Manufacturing a second substrate to maintain a constant distance between the second surface and the second surface; Combining the first and second substrates; And Forming a liquid crystal layer between the first and second substrates. The method of claim 4, wherein manufacturing the second substrate comprises: Forming a light shielding film on the second substrate; Forming a color filter formed of R, G, and B pixels on the second substrate on which the light shielding film is formed; Forming a photosensitive organic insulating layer on the second substrate on which the color filter and the light shielding film are formed; Patterning the photosensitive organic insulating layer using a photoresist process to form a protective film having the second unevenness formed thereon; And And forming a common electrode on the passivation layer in a uniform thickness.