KR20050066640A - Array substrate for use in reflective lcd and method of fabricating the same - Google Patents

Abstract

The present invention relates to a reflective liquid crystal display device, and to a reflective liquid crystal display device having a COT structure in which a color filter is formed on an array substrate.

The array substrate for a reflective liquid crystal display device according to the present invention includes a black matrix, a color filter, a drain electrode and a reflective electrode made of the same material in the same process. The reflective electrode is integrally formed with the drain electrode and positioned in the pixel area to serve to reflect light incident from the outside again, and to reduce power consumption of the liquid crystal display device.

In such a structure, since the reflective electrode is integrally formed with the drain electrode in the same process, there is an advantage that the process of manufacturing an array substrate for a reflective liquid crystal display device having a color filter on TFT (COT) structure can be simplified.

Description

Array Substrate for Use in Reflective LCD and Method of Fabricating the Same}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflective liquid crystal display device, and more particularly, to an array substrate for a reflective liquid crystal display device having a color filter on TFT (COT) structure constituting a color filter on the thin film transistor array unit, and a manufacturing method thereof.

In general, a liquid crystal display device displays an image by using optical anisotropy and birefringence characteristics of liquid crystal molecules. When an electric field is applied, the alignment of liquid crystals is changed, and the characteristics of light transmission vary according to the arrangement direction of the changed liquid crystals.

In general, a liquid crystal display device is formed by arranging two substrates on which electric field generating electrodes are formed so that the surfaces on which the two electrodes are formed face each other, injecting a liquid crystal material between the two substrates, and then applying a voltage to the two electrodes. By moving the liquid crystal molecules by the electric field is a device that represents the image by the transmittance of light that varies accordingly.

1 is a view schematically showing a general transmissive liquid crystal display device.

As shown, the upper substrate 5 of the general color liquid crystal display device 11 includes a color filter composed of the sub color filters 8 and a black matrix 6 formed between each sub color filter 8, It also includes a common electrode 18 deposited on each sub color filter 8 and the black matrix (6). In the lower substrate 22 of the color liquid crystal display apparatus 11, the pixel electrode 17 and the switching element T are formed in the pixel region P, and array wiring is formed around the pixel region P. FIG. The liquid crystal 14 is filled between the upper substrate 5 and the lower substrate 22.

The lower substrate 22 is also referred to as an array substrate, and the thin film transistor T, which is a switching element, is positioned in a matrix type, and the gate wiring 13 crosses the plurality of thin film transistors TFT. ) And data wirings 15 are formed.

In this case, the pixel area P is an area defined by the gate wiring 13 and the data wiring 15 intersecting. A transparent pixel electrode 17 is formed on the pixel area P as described above.

The pixel electrode 17 uses a transparent conductive metal having a relatively high transmittance of light, such as indium-tin-oxide (ITO).

A storage capacitor C connected in parallel with the pixel electrode 17 is formed on the gate wiring 13, and a part of the gate wiring 13 is used as the first electrode of the storage capacitor C, and a second As the electrode, an island-shaped storage metal layer 30 formed of the same material as the source and drain electrodes is used.

In this case, the island-shaped storage metal layer 30 is configured to be in contact with the pixel electrode 17 to receive a signal of the pixel electrode.

As described above, when the upper color filter substrate 5 and the lower array substrate 22 are bonded to each other to produce a liquid crystal panel, light leakage defects due to the bonding error between the color filter substrate 5 and the array substrate 22 may be reduced. It is very likely to occur.

A description with reference to FIG. 2 is as follows.

FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1.

As described above, the first substrate 22, which is an array substrate, and the second substrate 5, which is a color filter substrate, are spaced apart from each other, and the liquid crystal layer 14 is disposed between the first and second substrates 22, 5. This is located.

The thin film transistor T including the gate electrode 32, the active layer 34, the source electrode 36, and the drain electrode 38 is disposed on the array substrate 22, and the thin film transistor T is disposed on the thin film transistor T. A protective film 40 is configured to protect it. A gate dielectric film 16 is interposed between the gate electrode 32 and the active layer 34 to insulate the gate electrode 32.

In the pixel region P, a transparent pixel electrode 17 is formed in contact with the drain electrode 38 of the thin film transistor T. A storage capacitor C connected in parallel with the pixel electrode 17 includes a gate line 13. It is configured on the top.

The upper substrate 5 includes a black matrix 6 corresponding to the gate wiring 13, the data wiring 15, and the thin film transistor T, and corresponds to the pixel region P of the lower substrate 22. The color filters 8a, 8b and 8c are thus constructed.

In this case, the general array substrate is configured such that the data line 15 and the pixel electrode 17 are spaced apart by a predetermined distance A to prevent vertical cross talk, and the gate line 13 and the pixel electrode are spaced apart from each other. (17) It is also configured to be spaced apart by a predetermined interval (B).

Since the spaces A and B spaced apart between the data line 15 and the gate line 13 and the pixel electrode 17 are areas where light leakage occurs, a black matrix formed on the upper color filter substrate 5 matrix) (6) will cover this part.

In addition, the black matrix 6 formed on the thin film transistor T serves to block light so that light incident from the outside does not affect the active layer 34 through the passivation layer 40. .

However, a misalignment may occur during the process of bonding the upper substrate 5 and the lower substrate 22. In view of this, a margin of a constant value is determined when designing the black matrix 6. Since the design is carried out with reference to), the aperture ratio decreases by that amount.

In addition, in the case where the bonding error beyond the margin occurs, there is often a light leakage defect in which the light leakage regions A and B are not covered by the black matrix 6.

In this case, since the light leakage appears outside, there is a problem of degrading the image quality of the liquid crystal display.

Conventionally, an example of configuring the color filter and the black matrix together with a thin film transistor on a single substrate has been proposed as a method for solving the above problems.

A description with reference to FIG. 3 is as follows.

3 is an enlarged plan view of a portion of an array substrate for a reflective liquid crystal display device having a COT structure according to the related art.

As shown in the drawing, the gate wires 52 extending in one direction on the substrate 50 are parallel to each other and are parallel to the gate wires 52 to define the pixel region P. The wiring 66 is configured.

The thin film transistor T including the gate electrode 54, the active layer 58, the source electrode 62, and the drain electrode 64 is formed at the intersection of the gate wiring 52 and the data wiring 66. .

Color pixels 72a, 72b, 72c representing red (R), green (G), and blue (B) are formed in the pixel region (P), and the upper portion of the color filters (72a, 72b, 72c) The pixel electrode 80 in contact with the drain electrode 64 is configured.

In the above-described configuration, the black matrix 74 is formed corresponding to the gate wiring 52, the data wiring 66, and the thin film transistor.

At this time, when the color filters 72a, 72b, and 72c are arranged in the same color region in the up and down neighboring pixel regions, the black matrix 74 need not be formed on the gate wiring 52. .

4A to 4G, a manufacturing process of a reflective liquid crystal display autonomous array substrate having a conventional COT structure having the above-described configuration will be described.

4A to 4G are cross-sectional views taken along the line IV-IV of FIG. 3 and shown according to a conventional process sequence.

First, as shown in FIG. 4A, a selected one of a group of conductive metals including copper (Cu), tungsten (W), chromium (Cr), molybdenum (Mo), and the like is deposited on the substrate 50, and the first layer is deposited. Patterning is performed by a mask process to form the gate wiring 52 and the gate electrode 54 connected thereto.

Next, one selected from the group of inorganic insulating materials including silicon nitride (SiN _x ) and silicon oxide (SiO ₂ ) is deposited on the entire surface of the substrate 50 on which the gate wiring 52 and the gate electrode 54 are formed. The gate insulating film 56 is formed.

Next, as shown in FIG. 4B, a pure amorphous silicon layer (a-Si: H) and an amorphous silicon layer (n ⁺ a-) containing impurities are formed on the entire surface of the substrate 50 on which the gate insulating layer 56 is formed. Si: H) is laminated and patterned by a second mask process to form an active layer 58 and an ohmic contact layer 60 stacked in an island shape on the gate insulating film 56 corresponding to the gate electrode 54. Form.

Next, as shown in FIG. 4C, the conductive metal as described above is deposited on the entire surface of the substrate 50 on which the ohmic contact layer 60 is formed, and patterned by using a third mask process to form an upper portion of the ohmic contact layer 60. Source electrodes 62 and drain electrodes 64 are spaced apart from each other. In addition, the data line 66 is connected to the source electrode 62 and extends in a direction perpendicular to the gate line 52 to define the pixel area P.

At the same time, an island-shaped storage metal layer 68 is further formed on a portion of the gate wiring 52.

Subsequently, the ohmic contact layer 60 exposed to the spaced apart regions of the source and drain electrodes 62 and 64 is etched to expose the lower active layer 58.

Next, one selected from the group of inorganic insulating materials including silicon nitride (SiN _X ) and silicon oxide (SiO ₂ ) is deposited on the entire surface of the substrate 50 on which the source and drain electrodes 62 and 64 are formed. The protective film 70 is formed.

Next, as shown in FIG. 4D, color filters 72a and 72b are formed on the first passivation layer 70 corresponding to the pixel region P. Next, as shown in FIG.

The color filters 72a and 72b form color filters representing red (R), green (G), and blue (B) in a plurality of pixel areas (P) according to a specific arrangement order, for each color filter of each color. It is patterned sequentially, but at the same time using the same mask.

Therefore, the color filter may be formed by a fourth mask process.

Subsequently, as shown in FIG. 4E, a photosensitive black organic layer is coated on the substrate 50 on which specific color filters 72a and 72b are formed for each pixel region P, and patterned by a fifth mask process. The black matrix 74 is formed on the upper portion corresponding to the 66, the gate wiring 52, and the thin film transistor T.

At this time, when the color filter of the same color is formed in one direction in the pixel area adjacent to the newly direction in the plane, since the color filter is formed on the upper portion of the gate wiring, as shown in FIG. It is not necessary to form the brick matrix 74 in the upper part.

Next, as shown in FIG. 4F, the drain electrode 64, the first passivation layer 70 and the color filter on the island-shaped storage metal layer 68 are patterned by a sixth mask process to form a drain contact hole ( 76 and a storage contact hole 78.

Next, as shown in FIG. 4G, indium tin oxide (ITO) and indium zinc oxide (IZO) are formed on the entire surface of the substrate 50 on which the color filters 72a and 72b and the black matrix 74 are formed. And depositing one selected from the group of transparent conductive materials including the patterned layer and patterning the same by the seventh mask process to simultaneously contact the drain electrode 64 and the island-shaped storage metal layer 68. The pixel electrode 80 is formed.

In the above-described configuration, the island-shaped storage metal layer 68 in contact with the pixel electrode 80 is the first electrode, and the lower gate wiring 52 overlapping the gate wiring 52 is formed on the first electrode. A storage capacitor portion C _ST serving as a two electrode is formed.

According to the above process, a conventional array substrate for a transmissive liquid crystal display device having a COT structure can be manufactured.

Since the array substrate and the transmissive liquid crystal display device as described above do not have their own light emitting devices, a backlight, which is a light source, is positioned under the array substrate. However, the power consumed in the backlight is relatively large, resulting in a large capacity of the power supply. The power supply device has also been a problem because of the limited use time, and the need for a reflective liquid crystal display device that does not use a backlight light source has been raised to solve such problems.

The present invention relates to an array substrate of a reflective liquid crystal display device to solve the above problems. Since the reflective liquid crystal display operates using external light, the amount of power consumed can be greatly reduced. In the array substrate used in the reflective liquid crystal display device having the COT structure according to the present invention, a reflective plate or a reflective electrode having an opaque reflective characteristic is used in the pixel portion where the transparent electrode is formed in the conventional transmissive liquid crystal display device. Compared with the conventional liquid crystal display device, less power consumption can be achieved.

According to an aspect of the present invention, there is provided an array substrate for a reflective liquid crystal display device including: a gate wiring disposed on a substrate and including a gate pad at one end thereof; A gate insulating layer disposed over the gate pad and the gate wiring and exposing the gate pad; A data line disposed on the gate insulating film and defining a pixel region by crossing the gate line vertically; A thin film transistor positioned at an intersection point of the gate line and the data line and including a gate electrode, a semiconductor layer, a source electrode, and a drain electrode; A first pixel electrode formed of the same material as that of the data wiring and integrally formed with the drain electrode in the same process and formed of a conductive material having a high reflectance; A black matrix positioned on an upper portion of the thin film transistor and the data line and a portion of the gate line; A color filter layer positioned on each pixel area on the first pixel electrode; A protective layer having the black matrix and a color filter layer formed on the front surface of the substrate and exposing a part of the first pixel electrode and the gate pad; And a transparent second pixel electrode positioned on the passivation layer and in contact with the first pixel electrode and independently patterned for each pixel region.

The array substrate for a reflective liquid crystal display device further includes an inorganic insulating layer disposed on a front surface of the substrate on which the data line, the source electrode, the drain electrode, and the first pixel electrode are formed to expose a portion of the first pixel electrode and the gate pad. . In the array substrate for a reflective liquid crystal display device, the inorganic insulating film is formed between the thin film transistor and the black matrix. The inorganic insulating film is one of silicon nitride and silicon oxide, and the protective layer is one selected from an organic insulating film and an inorganic insulating film. The semiconductor layer includes an active layer of pure amorphous silicon on an upper portion of the gate electrode, and an ohmic contact layer in amorphous silicon containing impurities and contacting the source and drain electrodes. In addition, the semiconductor layer is formed to extend under the data wiring, or is formed in an island shape on the gate electrode. In the array substrate for a reflective liquid crystal display device, the first pixel electrode is selected from a group of highly reflective conductive materials composed of aluminum (Al), aluminum alloy (AlNd), and silver (Ag). The second pixel electrode is composed of one of indium tin oxide (ITO) and indium zinc oxide (ITO). The color filter includes red, green, and blue color filters corresponding to each pixel area. In the reflective liquid crystal display array substrate, the first pixel electrode overlaps a part of the gate wiring, and the lower gate wiring is the first electrode and the upper first pixel electrode is the second electrode. A storage capacitor having a dielectric of a gate insulating film interposed therebetween is formed. The array substrate for a reflective liquid crystal display device further includes a gate pad terminal formed of the same material on the gate pad in the same process as the second pixel electrode.

According to another aspect of the present invention, there is provided a method of manufacturing an array substrate for a reflective liquid crystal display device, including forming a gate wiring including a gate pad at one end and a gate electrode extending from the gate wiring on a substrate; Forming a gate insulating film on an entire surface of the substrate on which the gate wiring, the gate pad, and the gate electrode are formed; Forming an alumina layer including an active layer made of pure amorphous silicon and an ohmic contact layer made of impurity amorphous silicon on the gate electrode upper gate insulating film; Forming and patterning a highly reflective conductive material on the entire surface of the substrate on which the semiconductor layer is formed, the data line perpendicularly intersects the gate line and defines a pixel region together with the gate electrode, and extends from the data line to the top of the ohmic contact layer. Forming a first pixel electrode in the pixel region integrally with a source electrode, a source electrode separated from the source electrode, a drain electrode on the ohmic contact layer, and a drain electrode; Forming a first protective layer on an entire surface of the substrate so as to cover the patterned highly conductive material; Forming a black matrix on the drain electrode, the source electrode, the data wiring, and the gate wiring; Forming a color filter layer on each pixel area of the substrate on which the black matrix is formed; Forming a second passivation layer on the substrate on which the black matrix and the color filter layer are formed; Simultaneously etching the first and second passivation layers to form a first contact hole exposing the first pixel electrode, and simultaneously etching the first and second passivation layers and the gate insulating layer to expose a gate pad. Forming a contact hole; Forming and patterning a transparent conductive material on the entire surface of the substrate on which the first and second contact holes are formed, thereby forming a second pixel electrode directly contacting the first pixel electrode through the first contact hole in each pixel region; Characterized in that.

The method of manufacturing an array substrate for a reflective liquid crystal display device may further include a thin film transistor including a gate electrode, an active layer, an ohmic contact layer, a source electrode, and a drain electrode. In the method of manufacturing an array substrate for a reflective liquid crystal display device, the first protective layer is formed between the thin film transistor and the black matrix, and is selected from inorganic insulating materials including silicon nitride and silicon oxide. 2 The protective layer is formed of one selected from the group of organic insulators and inorganic insulators. The semiconductor layer is formed to extend below the data line or to have an island shape on the gate electrode. In the method of manufacturing an array substrate for a reflective liquid crystal display device, the first pixel electrode is selected from a group of highly reflective conductive materials including aluminum (Al), aluminum alloy (AlNd), and silver (Ag). The second pixel electrode is composed of one of indium tin oxide (ITO) and indium zinc oxide (ITO). The color filter includes red, green, and blue color filters corresponding to each pixel area. In the method of manufacturing an array substrate for a reflective liquid crystal display device, the first pixel electrode is overlapped with a part of the gate wiring so that the lower gate wiring is the first electrode and the upper first pixel electrode is the second electrode. A storage capacitor having a dielectric of a gate insulating film interposed therebetween is formed. The process of forming the second pixel electrode may further include forming a gate pad terminal formed of a transparent conductive material on the gate pad and directly contacting the gate pad through a second contact hole.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

In the reflective liquid crystal display device, the array substrate has a color filter on thin film transistor (COT) structure including a black matrix and a color filter, and the pixel electrode is integrated with the drain electrode of the thin film transistor. It is characterized by serving as a reflector that reflects light.

FIG. 5 is a plan view schematically illustrating a configuration of an array substrate for a reflective liquid crystal display device having a color filter on TFT (COT) structure according to the present invention, and FIG. 6 is a cross-sectional view taken along the cutting line VI-VI of FIG. 5. 7 is a cross-sectional view of the pixel portion, and FIG. 7 is a cross-sectional view taken along the cutting line VII-VII of FIG. 5, and is a cross-sectional view of the gate pad portion.

As shown in FIGS. 5 to 6, a gate line 102 extending in one direction is formed on the substrate 100, and the plurality of pixel regions P are vertically intersected with the gate line 102. A data line 118 is defined.

The thin film transistor T including the gate electrode 104, the semiconductor layer 112, and the source and drain electrodes 114 and 116 is formed at the point where the gate line 102 and the data line 118 cross each other. The gate electrode 104 extends from the gate wiring 102, and the source electrode 114 extends from the data wiring 118. The drain electrode 116 is spaced apart from the source electrode 116 by a predetermined interval. The semiconductor layer 112 includes an active layer 112a made of pure amorphous silicon material and an ohmic contact layer 112b made of impurity crystalline silicon. The semiconductor layer 112 may be formed in an island pattern pattern on the gate. As shown in FIG. 5, it may be configured to extend below the data line 118.

The first pixel electrode 120 is integrally formed using the same material as the drain electrode 116 of the thin film transistor T in the pixel region P defined by the intersection of the gate wiring 102 and the data wiring 118. Configure The first pixel electrode 120 is formed of the same material as the source and drain electrodes 114 and 116 in the same process. The first pixel electrode 120 is selected from a conductive material having excellent reflectance reflecting light. For example, aluminum (Al), aluminum alloy (AlNd), silver (Ag), or the like may be used as the material forming the first pixel electrode 120.

In the above-described configuration, a black matrix T is formed on the thin film transistor T and the data line 102, and a red color R is formed on each pixel region P on the first pixel electrode 120. And a color filter layer 126 of green (G) and blue (B). A portion of the first pixel electrode 120 overlaps the gate wiring 102 to form a storage capacitor C _ST . That is, a storage capacitor C having a lower gate wiring 102 as a first electrode, an upper first pixel electrode 120 as a second electrode, and a gate insulating film 108 interposed therebetween as a dielectric. _ST ) is formed.

In addition, the second pixel electrode 140 patterned for each pixel region P is positioned on the color filter layer 126. The second pixel electrode 140 is made of a transparent conductive material such as indium-tin-oxide (ITO) or indium-zinc-oxide (IZO). The second pixel electrode 140 is in contact with the first pixel electrode 120 through the first contact hole 130 and has a structure electrically connected to the storage capacitor C _ST .

As shown in FIGS. 5 and 7, a gate pad 106 positioned at one end of the gate wiring 102 is positioned on the substrate 100 in the gate pad part, and the gate insulating film 108 and the first protective layer are disposed on the substrate 100. 122 is formed to cover the gate pad 106. A second contact hole 132 exposing a part of the gate pad 106 is formed in the gate insulating layer 108 and the first passivation layer 122, and the gate pad terminal 142 is formed in the second contact hole 132. In contact with the gate pad 106 through. The gate pad terminal 142 is formed of the same material as the second pixel electrode 140 of FIG. 6 in the same process, and transmits an electrical signal input from the outside to the gate wiring 102 through the gate pad 106. Do it.

5 to 7, the black matrix 124 is positioned on the thin film transistor T array unit, and the first pixel electrode 120 reflecting the light and the light transmit the light. Red (R), green (G), and blue (B) color filter layers 126 are formed between the transparent second pixel electrodes. The black matrix 124 covers the light leakage region and is configured to correspond to the gate wiring 102, the data wiring 118, and the thin film transistor T. The black matrix 124 is formed by applying an opaque organic material, and serves to block light and also to serve as a protective film for protecting the thin film transistor (T).

In the above-described array substrate having a COT structure, since the first pixel electrode 120 integrally formed with the drain electrode 116 is made of a material having a high reflectance reflecting light, the liquid crystal display reflects light incident from the outside. Make the device work. That is, the first pixel electrode 120 also serves as a reflector.

Hereinafter, a method of manufacturing an array substrate for a liquid crystal display device according to an exemplary embodiment of the present invention will be described with reference to FIGS. 8A to 8F, 9A to 9F, and 10A to 10F.

8A to 8F are process plan views illustrating each process of forming the array substrate of FIG. 5, and FIGS. 9A to 9F and 10A to 10F are cut lines IX-IX and XX of FIGS. 8A to 8F. It is a process sectional drawing shown by the process sequence corresponding to each top view. Here, cutting lines IX-IX in FIGS. 8A to 8F are cutting lines between the thin film transistor and the pixel, and X-X is a cutting line of the gate pad portion.

8A, 9A, and 10A, a conductive metal is deposited and patterned on the substrate 100 to form a gate wiring 102 including a gate pad 106 at one end thereof, and a gate wiring 102. ) To form a gate electrode 104.

Next, as illustrated in FIGS. 8B, 9B, and 10B, silicon nitride (SiN _X ) is formed on the entire surface of the substrate 100 on which the gate wiring 102, the gate electrode 104, and the gate pad 106 are formed. One selected from the group of inorganic insulating materials including silicon oxide (SiO ₂ ) is deposited to form a gate insulating layer 108, which is a first insulating layer.

Next, pure amorphous silicon (a-Si: H) and amorphous silicon (n + a-Si: H) containing impurities are deposited on the gate insulating layer 108 and patterned to form an upper portion of the gate electrode 104. The semiconductor layer 112 including the active layer 112a and the ohmic contact layer 112b is formed on the gate insulating layer 108. The semiconductor layer 112 may be formed in an island shape on the gate electrode 104, and as shown in FIG. 8B, data wirings 118 of FIG. 8C are formed on and after the gate electrode 104. It may be formed extending in the position to be.

Next, as shown in FIGS. 8C, 9C, and 10C, aluminum (Al), aluminum alloy (AlNd), and silver are formed on the entire surface of the substrate 100 on which the active layer 112a and the ohmic contact layer 112b are formed. The source electrode 114 and the drain electrode 116 and the source electrode 112 which are in contact with the ohmic contact layer 112 are deposited by depositing and patterning a selected one of the conductive metal groups having excellent reflectivity such as (Ag). And a data line 118 connected to and vertically intersecting the gate line 102, and a first pixel electrode 120 including the pixel region 109 integrally with the drain electrode 116. After the pattern of the metal layer, the ohmic contact layer 112b exposed between the source electrode 114 and the drain electrode 116 is patterned to form a channel region in the lower active layer 112a. In this case, the source electrode 114 and the drain electrode 116 function as an etch stop layer. Therefore, the thin film transistor T including the gate electrode 104, the active layer 112a, the ohmic contact layer 112b, the source electrode 114, and the drain electrode 116 is completed by such a process.

Also, in such a configuration, since the first pixel electrode 120 is formed of a conductive metal having excellent reflectance, the first pixel electrode 120 serves as a reflective electrode, and is configured to overlap with a portion of the front gate wiring so that the storage capacitor C _{ST is} formed. Configure That is, in the storage capacitor C _ST , a portion of the gate wiring 102 is used as the first electrode, and a second pixel electrode covering the gate wiring 102 is used as the second electrode, and the gate insulating film interposed therebetween is formed. 108 is used as a dielectric.

Next, as shown in FIGS. 8D, 9D, and 10D, nitride is formed on the entire surface of the substrate 100 on which the source and drain electrodes 114 and 116, the data line 118, and the first pixel electrode 120 are formed. One selected from the group of inorganic insulating materials including silicon (SiN ₂ ) and silicon oxide (SiO ₂ ) is thickened to form the first protective layer 122. In this case, the function of the first passivation layer 122 serves to prevent a poor contact that may occur between the black matrix 124, which is an organic layer formed thereafter, and the active layer 112a. The first passivation layer 122 may not be formed unless contact failure occurs between the organic layer (black matrix) formed in a later step and the active layer 112a.

The process of forming the thin film transistor array unit through the above-described process is completed.

Next, an opaque organic material having a low dielectric constant is coated on the first passivation layer 122 to form a black organic layer, and then patterned to form a black organic layer. The black matrix 124 is formed on the upper part of the 102 and the data wiring 118. The black matrix 124 also serves to protect the thin film transistor (T). The black matrix 124 formed on the gate wiring 102 does not cover all of the gate wiring 102 and is configured to expose the lower first electrode.

Next, as shown in FIGS. 8E, 9E, and 10E, color resin is applied to the entire surface of the substrate 100 on which the black matrix 124 is formed, and red (R) is applied to the plurality of pixel regions P. FIG. And color filter layers 126 of green (G) and blue (B) are formed, respectively. In this case, the color filter layer 126 is formed on a portion other than where the black matrix 124 is formed, but is not formed on the storage capacitor (C _ST ).

Next, as illustrated in FIGS. 8F, 9F, and 10F, silicon nitride (SiN _X ) and silicon oxide (SiO ₂ ) are formed on the entire surface of the substrate 100 on which the black matrix 124 and the color filter layer 126 are formed. The second protective layer 128 is formed by depositing one selected from the group of inorganic insulating materials including or one selected from the group of organic insulating materials including benzocyclobutene (BCB) and an acrylic resin.

Subsequently, the second protective layer 128 and the first protective layer 122 are etched to expose the first contact hole 130 exposing a part of the first pixel electrode 120 on the gate electrode 102. Form. In addition, in the etching process of forming the first contact hole 130, the second protective layer 128, the first protective layer 126, and the gate insulating layer 108 are etched to expose the gate pad 106. The second contact hole 132 is formed.

Subsequently, as shown in FIGS. 5, 6, and 7, indium-tin-oxide (ITO) and indium-as described above on the entire surface of the substrate 100 on which the patterned second protective layer 128 is formed. A transparent conductive metal including zinc oxide (IZO) is deposited to form a transparent electrode layer. Subsequently, the transparent electrode layer is patterned to form a second pixel electrode 140 corresponding to the pixel region P. FIG.

The second pixel electrode 140 is in direct contact with the exposed first pixel electrode 120 through a first contact hole. That is, the transparent second pixel electrode 140 is in contact with the first pixel electrode 120 which is a reflective electrode with the color filter interposed therebetween.

Accordingly, the second pixel electrode 140 receives a signal from the drain electrode 116 through the first pixel electrode 120. In addition, since it contacts the exposed first pixel electrode 120, it is also connected to the storage capacitor C _ST .

In addition, at the same time as forming the second pixel electrode 140, the gate pad terminal 142 is formed of the same material as the second pixel electrode 140 as illustrated in FIG. 7. The gate pad terminal 142 is in direct contact with the gate pad 106 through the second contact hole 132.

According to the above process, an array substrate for a reflective liquid crystal display device having a COT structure according to the present invention can be manufactured. That is, a reflective array substrate having a COT structure in which the first pixel electrode 120 serves as a reflective electrode may be manufactured.

In the reflective array substrate having the COT structure as described above, since the black matrix 124 and the color filter layer 126 are formed on the lower substrate, the bonding margin does not have to be considered and the first pixel electrode 120 is a reflective electrode. ) Is formed together with the drain electrode 116 to simplify the process.

In the above-described array of COT structure reflective liquid crystal display devices of the present invention, since the thin film transistor, the array portion, the color filter, and the black matrix are formed on the same substrate, there is no need for a bonding margin when designing the black matrix. There is an advantage that can improve the aperture ratio.

In addition, since the first pixel electrode, which is a reflective electrode, is integrally formed with the drain electrode at the same time, the process time can be shortened and the cost can be reduced to improve product yield and price competitiveness. Unlike the transmissive type, the reflective liquid crystal display device has a latent advantage in that low power consumption can be obtained.

1 is a view schematically showing a configuration of a general transmissive liquid crystal display device;

FIG. 2 is a cross-sectional view of the liquid crystal display device taken along the line II-II of FIG. 1;

FIG. 3 is an enlarged plan view showing some pixels of an array substrate for a transmissive liquid crystal display device having a COT structure according to the prior art;

4A to 4G are cross-sectional views illustrating a process sequence according to the prior art, cut along IV-IV of FIG. 3,

5 is a plan view schematically illustrating a configuration of an array substrate for a reflective liquid crystal display device having a color filter on TFT (COT) structure according to the present invention;

6 is a cross-sectional view taken along the line VI-VI of FIG. 5, and is a cross-sectional view of the pixel portion.

7 is a cross-sectional view taken along the cutting line VII-VII of FIG.

8A through 8F are process plan views illustrating respective processes of forming the array substrate of FIG. 5;

9A to 9F are cross-sectional views illustrating a process sequence of a thin film transistor and a pixel to be cut along the cutting line IX-IX of FIGS. 8A to 8F to correspond to each plan view.

10A to 10F are cross-sectional views of the gate pad unit in order of cutting the cutting line X-X of FIGS. 8A to 8F to correspond to the plan views.

<Brief description of the main parts of the drawing>

100: substrate 102: gate wiring

104: gate electrode 114: source electrode

116: drain electrode 118: data wiring

120: first pixel electrode 124: black matrix

126: color filter layer 140 second pixel electrode

Claims (17)

A gate wiring located on the substrate; A gate insulating film positioned over the gate wiring; A data line positioned on the gate insulating film, the data line crossing the gate line and defining a pixel area; A thin film transistor positioned at an intersection point of the gate line and the data line and including a gate electrode, a semiconductor layer, a source electrode, and a drain electrode; A reflective electrode extending from the drain electrode to the pixel region; A black matrix positioned on the thin film transistor; A color filter layer positioned on each of the pixel areas on the reflective electrode; A transparent electrode positioned on the color filter layer and in contact with the reflective electrode Array substrate for a reflective liquid crystal display device comprising a. The method of claim 1, And a reflective electrode formed of the same material as the data line and formed integrally with the drain electrode in the pixel region in the same process. The method of claim 1, The gate pad may further include a gate pad formed at one end of the gate wiring. The gate pad may include a passivation layer formed on a front surface of the substrate on which the black matrix and the color filter layer are formed, and exposing a portion of the reflective electrode and the gate pad. And a gate pad terminal formed of the same material in the same process as that of the transparent electrode, wherein the gate insulating layer exposes the gate pad and the transparent electrode is independently patterned for each pixel region. Board. The method of claim 1, And an inorganic insulating layer disposed on the front surface of the substrate on which the data line, the source electrode, the drain electrode, and the reflective electrode are formed, and exposing a portion of the reflective electrode and the gate pad, wherein the inorganic insulating layer is formed between the thin film transistor and the black matrix. Array substrate for reflective liquid crystal display device. The method of claim 4, wherein And the inorganic insulating layer is one of silicon nitride (SiN _X ) and silicon oxide (SiO ₂ ), and the protective layer is one selected from an organic insulating layer and an inorganic insulating layer. The method of claim 1, And said semiconductor layer comprises an active layer of pure amorphous silicon on top of a gate electrode, and an ohmic contact layer comprising amorphous silicon containing impurities and contacting said source and drain electrodes. The method of claim 1, And the semiconductor layer is one formed to extend under the data line or formed in an island shape on the gate electrode. The method of claim 1, The reflective electrode is one selected from the group of highly reflective conductive materials composed of aluminum (Al), aluminum alloy (AlNd), and silver (Ag), and the transparent electrode is made of indium tin oxide (ITO) and indium zinc oxide. An array substrate for a reflective liquid crystal display device comprising one of oxides (ITOs), wherein the color filters include red, green, and blue color filters corresponding to each pixel area. The method of claim 1, The reflective electrode overlaps a portion of the gate wiring to form a storage capacitor having a lower gate wiring as a first electrode, an upper reflective electrode as a second electrode, and a gate insulating film interposed therebetween as a dielectric. Array substrate for reflective liquid crystal display device. Forming a gate wiring including a gate pad at one end on the substrate and a gate electrode extending from the gate wiring; Forming a gate insulating film on an entire surface of the substrate on which the gate wiring, the gate pad, and the gate electrode are formed; Forming a semiconductor layer on the gate insulating film on the gate electrode; Forming source and drain electrodes spaced apart from the semiconductor layer, a data line connected to the source electrode and crossing the gate wiring to define a pixel region, and a reflective electrode extending from the drain electrode to the pixel region; ; Forming a black matrix on the drain electrode and the source electrode; Forming a color filter layer on each pixel area of the substrate on which the black matrix is formed; Forming a transparent electrode on the color filter layer Array substrate manufacturing method for a reflective liquid crystal display device comprising a. The method of claim 10, The semiconductor layer includes an active layer made of pure amorphous silicon and an ohmic contact layer made of impurity amorphous silicon, and the reflective electrode is formed by forming and patterning a highly reflective conductive material on the entire surface of the substrate, and forming the source and drain electrodes. The array substrate manufacturing method for a reflective liquid crystal display device formed on the ohmic contact layer spaced apart from each other. The method of claim 10, Forming a first protective layer on an entire surface of the substrate to cover the reflective electrode; Forming a second passivation layer on the substrate on which the black matrix and the color filter layer are formed; Simultaneously etching the first and second passivation layers to form a first contact hole exposing the first pixel electrode, and simultaneously etching the first and second passivation layers and the gate insulating layer to expose a gate pad. 2 forming a contact hole Array substrate manufacturing method for a reflective liquid crystal display device further comprising. The method of claim 12, And the transparent electrode is in direct contact with the reflective electrode through the first contact hole. The method of claim 12, The forming of the transparent electrode may further include forming a gate pad terminal formed of a transparent conductive material on the gate pad and directly contacting the gate pad through the second contact hole. Array substrate manufacturing method. The method of claim 12, The first protective layer is formed of one selected from inorganic insulating materials including silicon nitride (SiN _X ) and silicon oxide (SiO ₂ ), and the second protective layer is formed of one selected from organic insulating materials and inorganic insulating materials, And the semiconductor layer extends below the data line or has an island shape on the gate electrode. The method of claim 10, The reflective electrode is one selected from the group of highly reflective conductive materials composed of aluminum (Al), aluminum alloy (AlNd), and silver (Ag), and the transparent electrode is made of indium tin oxide (ITO) and indium zinc oxide. And a color filter comprising red, green, and blue color filters corresponding to each pixel region, wherein the color filter comprises one of oxide (ITO). The method of claim 10, The reflective electrode overlaps a portion of the gate wiring to form a storage capacitor having a lower gate wiring as a first electrode, an upper reflecting electrode as a second electrode, and a gate insulating film interposed therebetween as a dielectric. A method of manufacturing an array substrate for a liquid crystal display device.