KR20020051455A - a method for fabricating reflective and transflective liquid crystal display device and the same - Google Patents

Abstract

PURPOSE: Reflective and transflective liquid crystal displays and method of fabricating the liquid crystal displays are provided to form a drain electrode and a pixel electrode of the same material on the same plane so as to reduce contact resistance and improve picture quality. CONSTITUTION: An array substrate of a reflective liquid crystal display includes a substrate(111), a data line(127) and a gate line(125) formed on the substrate, intersecting each other, to define a pixel region. The substrate further includes a switching element that is formed at the intersection of the gate line and the data line and consists of a gate electrode(132), source and drain electrodes(133,135) and an active layer, and a reflection electrode(119) extended from the drain electrode and placed on the pixel region. The drain electrode and the reflection electrode are formed of the same material.

Description

Reflective and transmissive liquid crystal display device and method for manufacturing the same {a method for fabricating reflective and transflective liquid crystal display device and the same}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and in particular, a reflective liquid crystal display device using a reflection mode, and a reflective liquid crystal display device capable of selectively using a reflection mode and a transmission mode. display substrate).

In general, the reflective liquid crystal display device does not require an additional light source device such as a backlight since the light source can be replaced with an external light source.

The reflective transmissive liquid crystal display device has the functions of a transmissive liquid crystal display device and a reflective liquid crystal display device at the same time, and may use both a backlight light and an external natural light or artificial light source, thereby limiting the surrounding environment. It does not receive, there is an advantage that can reduce the power consumption (power consumption).

1 and 2, a conventional array substrate for reflection transmissive liquid crystal display device will be described.

1 is a schematic plan view showing some pixels of an array substrate for a reflective liquid crystal display device.

As shown in the drawing, the array substrate for a reflective liquid crystal display device is configured such that the gate line 25 and the data line 27 vertically intersect in a plane to define the pixel region P, and at the intersection of the two lines The switching element T is formed.

The switching element T is generally used by forming a thin film transistor (TFT) composed of a gate electrode 32, a source electrode 33, a drain electrode 35, and an active layer 34.

The pixel electrode 19 is positioned on the pixel region P, and contacts the drain electrode 35 of the thin film transistor T to drive a liquid crystal (not shown).

The reflective electrode 19 is formed using an opaque conductive metal having excellent reflectance. Such an opaque metal material may be, for example, an aluminum-based metal including aluminum (Al) and an aluminum alloy (for example, AlNd).

The operation mode of the reflective liquid crystal display device including the array substrate having such a configuration will be briefly described.

As the light source of the reflection mode uses an external light source as described above, the light incident from the outside to the upper substrate (not shown) of the liquid crystal panel is reflected by the reflective electrode 19 formed on the array substrate 21 and is affected by the voltage. As the light passes through the aligned liquid crystal (not shown), the light is emitted in a state where the polarization state of the light is changed according to the birefringence characteristic of the liquid crystal.

In this way, the light emitted from the liquid crystal (not shown) passes through the color filter (not shown) to color the color filter to perform a red / green / blue color display function.

The cross-sectional structure of the reflective liquid crystal display device having such a configuration will be described below with reference to FIG. 2.

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

As shown, first, a gate electrode 32 and a gate wiring (25 in FIG. 2) are formed on the substrate 21, and the data wiring 27, the source electrode 33, and the drain electrode 35 are formed as described above. The gate insulating film 41 is formed between the gate electrode 32.

The active layer 34 overlaps the source electrode 33 and the drain electrode 35, respectively.

After forming the thin film transistor T including each electrode and the active layer, a protective layer 43 made of an insulating material for protecting the thin film transistor is formed.

Next, the protective layer 43 is patterned to form a drain contact hole 45 on the drain electrode 35, thereby forming a reflective electrode 19 in contact with the drain electrode 35. .

In the above-described process, a conventional array substrate for a reflective liquid crystal display device can be manufactured.

In the configuration as described above, in the prior art, the drain electrode and the reflective electrode were formed of different materials, and thus were formed in different layers.

Therefore, the reflective electrode and the drain electrode, which are pixel electrodes, are configured to contact each other through the contact hole.

In this configuration, a contact resistance is generated between the half-electrode 19 and the drain electrode 35 in the portion A where the two electrodes contact each other.

When a low data voltage below a predetermined level is applied to the drain electrode 35, the current flowing between the drain electrode 35 and the pixel electrode 19 is affected to adversely affect image quality.

3 is a partial plan view of an array substrate for a conventional transmissive liquid crystal display device.

As shown, the reflective transmissive liquid crystal display has a structure in which the transmissive portion A and the reflective portion B exist simultaneously in one pixel region P so that the reflective transmissive liquid crystal display can operate in both the reflective mode and the transmissive mode.

The means used to define the reflecting portion and the transmitting portion includes a reflecting electrode (or reflecting plate) 19a including a transmitting hole 51 and a transparent pixel electrode which may be formed on or under the reflecting electrode 19a. It consists of 19b.

The cross-sectional structure of such a configuration will be described below with reference to FIG. 4.

4 is a cross-sectional view taken along the line VV ′ of FIG. 3. (See FIG. 3).

First, the thin film transistor T including the gate electrode 32, the source electrode 33, and the drain electrode 35 is formed on the substrate 21, and then the first passivation layer 43 is formed on the thin film transistor. To form.

Next, a drain contact hole 45 is formed on the drain electrode 35 of the thin film transistor T.

Next, the reflective electrode 19a is formed on the pixel region P while contacting the drain electrode 35 through the drain contact hole 45 and including the transmission hole 51.

Next, the second protective layer 47, which is an insulating material, is formed on the reflective electrode 19a, and then patterned to form a reflective electrode (a portion of the portion contacting the drain electrode 35 through the drain contact hole 45). 19a) is exposed (a result of patterning the contact hole twice).

Next, the transparent pixel electrode 19b is formed to be positioned on the pixel region P while contacting the reflective electrode 19a exposed between the patterned second protective layers 47.

By such a process, a conventional array substrate for a reflective transmissive liquid crystal display device can be manufactured.

As described above, the structure of the pixel electrode and the drain electrode of the transmissive array substrate also has a problem of deterioration in image quality due to contact resistance, and in particular, since it is composed of a double layer pixel electrode, there is complexity in the process, and accordingly the manufacturing time increases. There are many inefficiencies, such as an increase in material costs.

In order to solve the above problems, the present invention proposes a structure in which the drain electrode and the reflecting electrode are integrated with the same material, and ensures reliability and improves the production yield.

FIG. 1 is an enlarged plan view schematically illustrating some pixels of a typical reflective liquid crystal display array substrate.

FIG. 2 is a cross-sectional view taken along line IV-IV ′ of FIG. 1;

FIG. 3 is an enlarged plan view schematically illustrating some pixels of a general array of reflective transmissive liquid crystal display devices;

4 is a cross-sectional view taken along the line VV ′ of FIG. 3;

5 is an enlarged plan view schematically illustrating a portion of an array substrate for a reflective liquid crystal display device according to a first embodiment of the present invention;

6A to 6C are cross-sectional views illustrating a process sequence by cutting along VI-VI ′ of FIG. 5;

7 is an enlarged plan view schematically illustrating a part of an array substrate for a reflective transmissive liquid crystal display device according to a second embodiment of the present invention;

8A to 8C are cross-sectional views illustrating a process sequence by cutting along the line VII-VII ′ of FIG. 7.

<Explanation of symbols for main parts of drawing>

111 substrate 119 reflective electrode

125: gate wiring 127: data wiring

132: gate electrode 133: source electrode

135: drain electrode P: pixel

An array substrate for a reflective liquid crystal display device according to the present invention for achieving the above object is a substrate; A data wiring and a gate wiring which vertically intersect the substrate and define pixel areas; A switching element configured at an intersection point of the gate wiring and the data wiring and including a gate electrode, a source electrode, a drain electrode, and an active layer; And a reflective electrode extending from the drain electrode of the switching element and positioned on the pixel area.

The drain electrode and the reflective electrode are formed of the same material.

The reflective electrode and the drain electrode are formed of aluminum and an aluminum-based alloy having low resistance and excellent reflectance.

The insulating layer is formed of one selected from the group of organic insulating materials consisting of benzocyclobutene (BCB) and acrylic resin.

According to another aspect of the present invention, an array substrate for a reflective transmissive liquid crystal display device includes a transparent substrate; A data wiring and a gate wiring which vertically intersect the substrate and define pixel areas; A switching element configured at an intersection point of the gate wiring and the data wiring and including a gate electrode, a source electrode, a drain electrode, and an active layer; A reflection electrode including a transmission hole in the pixel region and extending from the drain electrode; It includes a transparent pixel electrode formed through the reflective electrode and the insulating film.

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

First Embodiment

In the first embodiment, the structures of the drain electrode and the pixel electrode according to the present invention as described above are applied to an array substrate for a reflective liquid crystal display device.

5 is a plan view schematically illustrating a portion of an array substrate for a reflective liquid crystal display device according to a first embodiment of the present invention.

As illustrated, the gate line 125 and the data line 127 vertically intersect to define the pixel area P, and the switching element T is positioned at the intersection of the two wires.

The switching element T forms a thin film transistor T including a gate electrode 132, a source electrode 133, and a drain electrode 135.

The pixel region P extends from the drain electrode 135 to form a reflective electrode 119.

6A to 6C, a manufacturing process of an array substrate for a reflective liquid crystal display device according to a first embodiment of the present invention will be described.

6A to 6C are cross-sectional views illustrating a process sequence by cutting along VI-VI ′ of FIG. 5.

First, as shown in FIG. 6A, a conductive metal group including aluminum (Al), an aluminum alloy, molybdenum (Mo), copper (Cu), tungsten (W), chromium (Cr), and the like on the substrate 111. The selected one of them is deposited and patterned to form a gate wiring (125 in FIG. 5) and a gate electrode 132.

In this case, when the gate electrode 132 and the gate wiring 125 are made of aluminum, a structure in which other conductive metals protecting the aluminum wiring may be stacked.

Next, an inorganic insulating material group composed of a silicon oxide film (SiO ₂ ) and a silicon nitride film (SiN _x ) on the entire surface of the substrate 111 including the gate wiring 125 and the gate electrode 132. Accordingly, the gate insulating layer 141 is formed by depositing or applying one selected from the group of organic insulating materials including benzocyclobutene, acryl resin, and the like.

A pure amorphous silicon layer (a-Si: H; 134a) and an impurity amorphous silicon layer (n + a-Si: H; 134b) are stacked and patterned on the gate insulating layer 141 to form an upper portion of the gate electrode 132. The semiconductor layer 134 is formed in an island shape.

Next, as shown in FIG. 6B, the conductive metal material as described above is deposited on the entire surface of the substrate 111 on which the semiconductor layer 134 is formed, and then patterned to form the gate wiring (125 in FIG. 5). Is extended from the data line 127 defining the pixel area P to cross vertically, the source electrode 133 connected to the data line 127, the drain electrode 135 spaced apart from the drain electrode 135, and the drain electrode. The formed reflective electrode 119 is formed.

As a result, a structure in which the thin film transistor T is formed at a point where the gate wiring 125 and the data wiring 127 intersect on the substrate 111 is obtained.

Next, as shown in FIG. 6C, the protective layer 143 is formed by coating or depositing the above-described insulating material on the entire surface of the substrate 111 on which the thin film transistor T is formed.

In such a process, an array substrate for a reflective liquid crystal display device according to the present invention can be produced. In the above-described configuration, since the drain electrode 135 and the reflective electrode 119 are formed on the same layer with the same material, a contact hole forming process that is performed separately from the conventional process may be omitted.

In addition, since there is no contact resistance generated between the drain electrode 135 and the reflective electrode 119, poor image quality due to the contact resistance can be prevented.

-Second Example-

The second embodiment is an example in which the structure of the drain electrode pixel electrode according to the present invention as described above is applied to an array substrate for a reflective transmissive liquid crystal display device.

7 is a plan view showing some pixels of an array substrate for a reflective transmissive liquid crystal display device according to a second embodiment of the present invention.

As illustrated, the gate line 125 and the data line 127 vertically intersect on the substrate 111 to define the pixel region P, and the thin film transistor T is present at the intersection of the two wires. do.

The pixel region P is defined as a transmissive portion A and a reflective portion B. For this purpose, a reflective electrode 119a including a transmissive hole 141 is employed, and is transparent to an upper portion of the reflective electrode 119a. The pixel electrode 119b is formed.

The reflective electrode 119a is formed on the entire surface of the substrate 111, and the transmission hole 151 is formed in each pixel, and the drain electrode 135 of the thin film transistor T formed corresponding to each pixel is formed. Form an extension.

In the above-described structure, the transparent pixel electrode 119b is connected to the reflective electrode 119a through the contact hole 136.

Hereinafter, a manufacturing process for the configuration of FIG. 7 will be described with reference to FIGS. 8A to 8C.

8A to 8C are cross-sectional views taken along the line of the process of FIG.

First, as shown in FIG. 8A, the conductive metal as described above is deposited and patterned to form the gate wiring 125 and the gate electrode 132.

Next, the gate insulating layer 141 is formed by depositing or applying the above-described insulating material on the entire surface of the substrate 111 on which the gate wiring 125 and the gate electrode 132 are formed.

A pure amorphous silicon layer 143a and an impurity amorphous silicon layer 143b are stacked and patterned on the gate insulating layer 141 to form a semiconductor layer 134 in an island shape on the gate electrode 132.

Next, as shown in FIG. 8B, the conductive metal material as described above is deposited on the entire surface of the substrate 111 on which the semiconductor layer 134 is formed, and then patterned to form the gate wiring (125 in FIG. 7). Is extended from the data line 127 defining the pixel area P to cross vertically, the source electrode 133 connected to the data line 127, the drain electrode 135 spaced apart from the drain electrode 135, and the drain electrode. The formed reflective electrode 119 is formed.

At the same time, a transmission hole 151 for displaying a transmission mode is formed in an arbitrary region of the reflective electrode 119.

As a result, a structure in which the thin film transistor T is formed at a point where the gate wiring 125 and the data wiring 127 intersect on the substrate 111 is obtained.

Next, as shown in FIG. 8C, the protective layer 143 is formed by coating or depositing the above-described insulating material on the entire surface of the substrate 111 on which the thin film transistor T is formed.

The protective layer 143 is patterned to form a contact hole 136 partially exposing the drain electrode 135.

Next, a selected one of a transparent conductive group consisting of indium tin oxide (ITO) and indium zinc oxide (IZO) is deposited and patterned on the patterned protective layer, and the exposed drain electrode 135 At the same time, the transparent pixel electrode 119b formed to overlap the reflective electrode 119a in a planar manner is formed.

In this way, the reflective transmission liquid crystal display device according to the present invention can be manufactured.

As described above, since the reflective electrode 119a is formed to extend from the drain electrode 135, there is no contact resistance. Unlike the related art, a process of separately patterning the reflective electrode and the reflective electrode and the drain The contact hole process for connecting the electrodes can be omitted.

Therefore, introducing the structures of the drain electrode and the pixel electrode according to the present invention has the following effects.

First, since a separate contact hole process for connecting the drain electrode and the reflective electrode is omitted, the process can be simplified.

In particular, in the case of the reflective transmission type, a process of forming a separate reflective electrode pattern is further omitted.

Third, since there is no contact resistance between the reflective electrode and the drain electrode, the image quality is improved.

Claims (8)

A substrate; A data wiring and a gate wiring which vertically intersect the substrate and define pixel areas; A switching element configured at an intersection point of the gate wiring and the data wiring and including a gate electrode, a source electrode, a drain electrode, and an active layer; A reflective electrode extending from the drain electrode of the switching element and positioned on the pixel region Array substrate for a reflective liquid crystal display device comprising a. The method of claim 1, And the drain electrode and the reflective electrode are made of the same material. The method according to any one of claims 1 to 2, And the reflective electrode and the drain electrode are formed of one selected from the group consisting of a conductive metal group composed of aluminum and an aluminum-based alloy having low resistance and excellent reflectance. The method of claim 1, And the insulating layer is one selected from the group of organic insulating materials consisting of benzocyclobutene (BCB) and acrylic resin. A transparent substrate; A data wiring and a gate wiring which vertically intersect the substrate and define pixel areas; A switching element configured at an intersection point of the gate wiring and the data wiring and including a gate electrode, a source electrode, a drain electrode, and an active layer; A reflection electrode including a transmission hole in the pixel region and extending from the drain electrode; Transparent pixel electrode formed through the reflective electrode and the insulating film Array substrate for a transmissive liquid crystal display device comprising a. The method of claim 5, And the reflective electrode and the drain electrode are made of the same material. The method according to any one of claims 5 to 6, And the reflecting plate is formed of one selected from a group of conductive metals composed of aluminum and an aluminum-based alloy having excellent reflectance. The method of claim 5, And the insulating film is one selected from the group of organic insulating materials consisting of benzocyclobutene (BCB), acrylic resin, and the like.