KR20080002421A - Transflective liquid crystal display device and fabricating thereof - Google Patents

Abstract

A transflective LCD(Liquid Crystal Display) device and a manufacturing method thereof are provided to reduce production cost by forming integrally a white color filter and an overcoat layer and improve the quality of a transflective image by compensating the transmittance of the color filters of a reflection portion and a transmission portion. A transflective LCD device comprises a first substrate(110), a second substrate(130), a black matrix(132), RGB(Red, Green, Blue) color filters(133a), an overcoat layer(133b), and a common electrode(135). The black matrix is formed on the second substrate to be spaced from each other at regular intervals. The RGB color filters are formed on the second substrate and have different thicknesses for a unit filter. The overcoat layer is integrally formed with a white color filter on the second substrate. The common electrode is formed on the second substrate.

Description

Transflective liquid crystal display device and its manufacturing method {TRANSFLECTIVE LIQUID CRYSTAL DISPLAY DEVICE AND FABRICATING THEREOF}

1 is a cross-sectional view of a transflective liquid crystal display device according to the prior art.

2 is a plan view of the first and second substrates of the transflective liquid crystal display according to the present invention.

FIG. 3 is a cross-sectional view of the white unit pixel illustrated in FIG. 2.

4A to 4E are views showing the process steps of the second substrate along the cut plane I-I 'of FIG.

5 is a view showing a second substrate finally formed by back exposing the color pigments of R, G, and B with a halftone mask as another embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

130: second substrate 132: black matrix (BM)

133a: blue (B) color filter 133b: white (W) color filter integrated overcoat layer

135: common electrode 136: second alignment layer

The present invention relates to a transflective liquid crystal display device and a method for manufacturing the same, and more particularly, a white color filter in manufacturing a color filter substrate having red, green, blue, and white. And a white plus (W +) transflective liquid crystal display device and a method of manufacturing the same, which are intended to reduce the number of processes and the resulting manufacturing cost and contribute to the improvement of transflective image quality by integrally forming an overcoat layer.

 In general, a liquid crystal display device bonds two substrates on which electric field generating electrodes are formed to face each other, injects a liquid crystal material between the two substrates, and then applies liquid crystals to the liquid crystal molecules by applying a voltage to the two electrodes. By moving, it is a device for expressing the image by adjusting the transmittance of light that varies accordingly. However, as mentioned above, the liquid crystal display device requires a separate light source because it is a light receiving device that cannot emit light by itself. Therefore, a backlight device is provided on the rear surface of the liquid crystal panel and the light emitted from the backlight is incident on the liquid crystal panel to adjust the amount of light according to the arrangement of the liquid crystals to display an image. In this case, the field generating electrode of the liquid crystal display device is formed of a transparent conductive material, the two substrates should also be made of a transparent substrate.

Such a liquid crystal display device corresponds to a transmission type liquid crystal display device. Since an artificial back light source such as a backlight is used, a bright image may be realized even in a dark external environment, but power consumption due to the backlight is increased.

It is nonetheless a reflection type liquid crystal display device designed to compensate for this disadvantage. This is a form in which light transmittance is adjusted according to the arrangement of liquid crystals by reflecting external natural or artificial light, which consumes less power than a transmissive liquid crystal display. However, since the reflection type liquid crystal display device has a structure in which most of the light depends on external natural light or artificial light source, it is less power-consuming than the transmission type liquid crystal display device but cannot be used in a dark place.

Accordingly, a liquid crystal display device having both a reflection and a transmission has been proposed as a device capable of appropriately selecting and using two modes of reflection and transmission.

Next, a general transflective liquid crystal display device will be described in detail with reference to the accompanying drawings. 1 is a partial cross-sectional view of a general transflective liquid crystal display device. As shown in the figure, the first substrate 11 and the second substrate 31 are arranged at a predetermined interval. First, a gate electrode 12 is formed on the first substrate 11 below the gate. The insulating film 13 is formed. Of course, before the gate insulating layer 13 is formed, a gate wiring connected to the gate electrode 12 is further formed below.

Next, the active layer 14 and the ohmic contact layers 15a and 15b are sequentially formed on the gate insulating layer 13, and the source and drain electrodes 16a and 16b are formed again on the ohmic contact layers 15a and 15b. The source and drain electrodes 16a and 16b are formed together with the gate electrode 12 to form a thin film transistor. Of course, here as before, a data line (not shown) of a material such as the source and drain electrodes 16a and 16b is additionally formed on the gate insulating layer 13, and the data line is connected to the source electrode 16a and the gate The pixel area is defined by crossing the wiring.

Subsequently, a first passivation layer 17 made of an organic material is formed on the source and drain electrodes 16a and 16b to cover the thin film transistor. In addition, a reflective plate 18 made of an opaque conductive material is formed in the pixel area on the first passivation layer 17, and a second passivation layer 19 is formed thereon. Here, the second protective layer 19 has a contact hole 19a exposing the drain electrode 16b together with the first protective layer 17.

A pixel electrode 20 made of a transparent conductive material is formed in the pixel area on the second protective layer 19, and the pixel electrode 20 is connected to the drain electrode 16b through the contact hole 19a. . The pixel electrode 20 here serves as a transmission electrode, of course. When such a process is completed, the first alignment layer 21 is subsequently formed.

On the other hand, a black matrix 32 is first formed on the second substrate 31, and then red, green, blue, and white colors are formed between the black matrices. The filters 33a and 33b are sequentially formed repeatedly. Here, one color filter as well as color filters 33a and 33b correspond to one pixel electrode 20, and the black matrix 32 covers edges of the thin film transistor and the pixel electrode 20.

An overcoat layer 34 is formed on the color filters 33a and 33b to protect and planarize the color filters 33a and 33b, and acrylic and polyimide resins are usually used.

Next, a common electrode 35 made of a transparent conductive material is formed on the overcoat layer 34, and a second alignment layer 36 is formed on the common electrode 35.

The liquid crystal layer 40 is positioned between the first and second alignment layers 21 and 36. The liquid crystal used here is usually a twisted nematic liquid crystal, and the liquid crystal of the liquid crystal layer 40 The molecules 41 are constantly arranged with a pretilt angle with respect to the substrate.

However, in such a conventional configuration, the color filter for each color of R, G, B, and W is formed by a repeated photolithography process, which complicates the manufacturing process and the corresponding manufacturing cost. There is also a problem that increases.

Accordingly, an object of the present invention is to reduce the number of manufacturing steps and the manufacturing cost thereof by forming white pigments and overcoat layers integrally at the same time during the color filter substrate manufacturing process.

And the achievement of this object can be further embodied through the present invention. That is, the transflective liquid crystal display according to the present invention comprises: a first substrate; A second substrate; A black matrix formed on the second substrate at predetermined intervals; Red, green, and blue color filters having different thicknesses of unit filters formed on the second substrate; An overcoat layer integrally formed with a white color filter on the second substrate; It characterized in that it comprises a common electrode formed on the second substrate.

In addition, the manufacturing method of the transflective liquid crystal display device according to the present invention comprises the steps of providing a first substrate; Providing a second substrate; Forming a black matrix on the second substrate; Forming color filters of R and G having different thicknesses of unit filters on the second substrate; Depositing a color pigment of B on said second substrate; Exposing and developing on said second substrate using a halftone mask; Etching a portion of B on the second substrate; Depositing a W color pigment on an entire surface including a region of a W color filter on the second substrate; And forming a common electrode on the second substrate.

Then, with reference to the drawings with respect to the above configuration and manufacturing method will be described in detail. 2 is a perspective view of first and second substrates of a transflective liquid crystal display device according to the present invention, in which R, G, B, and W are one dot. As shown in the drawing, on the first substrate 110, the reflector F having the reflecting plate 118 formed at the lower portion corresponding to the pixel region P and the conductive material of the reflecting plate 118 at the center thereof are formed. The transmissive part T is removed, and as a whole, the reflecting plate 118 corresponding to the pixel area P on the second substrate 130 has a rectangular frame shape. In addition, an overcoat layer formed integrally with the R, G and B color filters 133a formed between the black matrix 132 and the black matrix 132 and the W color filter formed thereon on the second substrate 130. 133b), a common electrode 135, and the like are formed.

3 is a cross-sectional view of a unit pixel of W after bonding the first substrate 110 and the second substrate 130 of FIG. 2 according to the present invention. As shown in the figure, the thin film transistor formed on the lower first substrate 110 includes a gate electrode 112 to which a scan signal is applied, an active layer 114 to transmit a data signal in response to the scan signal, and A gate insulating film 113 that electrically isolates the active layer 114 and the gate electrode 112, a source electrode 116a formed on both sides of the active layer 114 to apply a data signal, and data; And a drain electrode 116b for applying a signal to the reflective electrode. In addition, a first protective film 117 and a second protective film 119 for protecting the thin film transistor including the source / drain electrodes 116a and 116b are additionally included. Of course, the first protective film 117 is included here. ) And a contact hole 119a and a first alignment layer 121 exposing the reflective plate 118 and the drain electrode 116b formed between the second protective layer 119 and the second passivation layer 119.

On the other hand, the black matrix 132 formed on the second substrate 130 corresponding to the above thin film transistor, and the reflective portion formed on the first substrate 110 in correspondence with the pixel area on the first substrate 110. The overcoat layer 133b formed integrally with the R, G, and B color filters 133a and the W color filter on the second substrate 130 having different thicknesses corresponding to F) and the transmissive portion T again is The common electrode 135 for driving the liquid crystal and the second alignment layer 136 are formed on the entire surface of the overcoat layer 136b.

Now, a method of manufacturing a color filter substrate according to the present invention will be described in detail with reference to FIGS. 4A to 4E. 4A shows a process of forming a black matrix. First, the second substrate 130, such as a glass substrate, is cleaned, and then on the second substrate 130, chromium / chromium oxide (Cr / CrOx), which is used as a black matrix material, is deposited by sputtering, and then photolithography. The Cr / CrOx layer is selectively patterned through an exposure and development process using a process technology to form a plurality of black matrices 132 having a predetermined space.

When the process of forming the black matrix 132 as described above is finished, color filters are formed as shown in FIG. 4B, respectively, and for the sake of convenience, R, G, and B may be formed in the R and G steps. In detail, the first color pigment of R is deposited on the black matrix 132, and then the halftone exposure and development process using the photolithography process technology are repeated to form the color filter 133a of R. Subsequently, G color filter 133b is formed in the same manner. Of course, each unit color filter may be formed by varying thicknesses corresponding to the reflecting portion F and the transmitting portion T formed on the first substrate 110.

4C illustrates the process of forming the color filter of B, which has been described in more detail in the foregoing process of forming R and G. In other words, it can be said that the color filters of R and G described above are made in the same way as the color filter forming method of B in this section. In other words, the B color filter forms R and G color filters 133a and 133b having different thicknesses corresponding to the reflecting portion F and the transmissive portion T formed on the first substrate 110. After depositing the color pigment 133 of B again on the front surface of the second substrate 130, the half-tone exposure and development process using the photolithography process technology corresponds to the pixel region on the first substrate 110. The reflective part F semi-transmits light using a mask, and the transmissive part T corresponding to the pixel area not only blocks the light, but also completes the B color filter by opening all other areas. .

Subsequently, as shown in FIG. 4D, the W color pigment is deposited on the entire surface of the second substrate 130 including the W color filter formation region to form a single body. In the present invention, such a process step is referred to as an overcoat layer 133d formed integrally with a white color filter.

Then, a common electrode is formed as shown in FIG. 4E. In other words, when the process of forming the overcoat layer 133d integrally formed with the above W color filter is completed, the common electrode 136 is formed together with the pixel electrode on the first substrate 110 to operate the liquid crystal cell. Here, the common electrode 136 is made of a transparent metal material such as indium tin oxide (ITO). Of course, the second alignment layer 136 is formed on the common electrode 135, although not shown in the drawing.

However, this manufacturing method can be accomplished in any other way. For example, the color filters of R, G, and B having different thicknesses on the second substrate 130 formed corresponding to the reflecting portion F and the transmitting portion T on the first substrate 110 may be halftone masks. It may be formed by exposing from the bottom, that is, the back of the second substrate 130 using. That is, when FIG. 5 is compared with the drawing of FIG. 4D, the difference is that the etching portions of the R, G, and B color filters of the second substrate 130 formed corresponding to the transmission portion T of the first substrate 110 are separated. You can see that it is located opposite.

Meanwhile, the color filter forming method up to now has different thicknesses of the color filter on the second substrate 130 depending on how the reflecting portion F and the transmitting portion T are formed on the first substrate 110. In addition, the configuration may also look slightly different depending on how the sub color filter is arranged to form a dot on the second substrate 130 based on R, G, B, and W. Since the configuration and formation method are the same, the scope of the present invention will extend to the W + transflective liquid crystal display including the above area and the manufacturing method thereof.

The transflective liquid crystal display device according to the present invention by the configuration and manufacturing method up to now to reduce the manufacturing cost according to the reduction of the number of processes, and also to improve the transflective image quality by compensating the transmittance of the color filter of the reflecting portion and the transmitting portion You can do it.

Claims (5)

A first substrate; Second substrate; A black matrix formed on the second substrate at predetermined intervals; Red, green, and blue color filters having different thicknesses of unit filters formed on the second substrate; An overcoat layer integrally formed with a white color filter on the second substrate; A transflective liquid crystal display device comprising a common electrode formed on the second substrate. The semiconductor device of claim 1, wherein the first substrate comprises: a gate electrode formed on the first substrate; A gate insulating film formed on the gate electrode; A semiconductor layer formed on the gate electrode and the gate insulating film; Source and drain electrodes formed on the semiconductor layer; A first passivation layer formed on the source and drain electrodes; A reflection plate formed on the first passivation layer; A second protective film formed on the reflective plate; A transflective liquid crystal display device comprising a pixel electrode formed on the second passivation layer. Providing a first substrate; Providing a second substrate; Forming a black matrix on the second substrate; Forming color filters of R and G having different thicknesses on the second substrate; Applying the color pigment of B onto the second substrate; Exposing and developing using a halftone mask on the second substrate; Etching a portion of B on the second substrate; Applying a W color pigment on the entire surface including an area of the W color filter on the second substrate; And A method of manufacturing a transflective liquid crystal display device comprising forming a common electrode on the second substrate. The method of claim 3, wherein providing the first substrate comprises: forming a gate electrode on the first substrate; Forming a gate insulating film on the gate electrode; Forming a semiconductor layer on the gate electrode and the gate insulating film; Forming a source and a drain electrode on the semiconductor layer; Forming a first passivation layer on the source and drain electrodes; Forming a reflector on the first passivation layer; Forming a second passivation layer on the reflecting plate; And forming a pixel electrode on the second passivation layer. The method of claim 3, wherein the forming of the R, G color filters having different thicknesses on the second substrate comprises: depositing respective R, G color pigments; Exposing and developing a halftone mask; A method of manufacturing a transflective liquid crystal display device comprising etching according to the degree of exposure.

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