KR20040061811A - a array substrate and the fabrication method for LCD - Google Patents

Abstract

PURPOSE: An array substrate of an LCD device is provided to form a nitride metal layer by injecting a nitrogen gas as depositing a reflector material on an organic insulated film, and to form patterns after depositing a reflective electrode on the nitride metal layer, thereby easily controlling an etching CD(Critical Dimension) process. CONSTITUTION: On a glass substrate(200), plural data lines for applying data signals to a source electrode(251) and plural gate lines for applying gate signals to a gate electrode(230) are crossed each other in matrix type. An area formed by the crossed data lines and the gate lines is a pixel area, and reflective electrodes(290) are formed in the pixel area. On the reflective electrodes(290), nitride aluminum layers and aluminum layers are sequentially accumulated.

Description

Array substrate and method of manufacturing the same for a liquid crystal display device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an array substrate of a liquid crystal display device and a method of manufacturing the same, and more particularly, to an array substrate having improved contact characteristics between an organic film and a reflective electrode and a method of manufacturing the same.

In general, CRT (or CRT: Cathode Ray Tube) has been the most used screen display device for displaying image information on the screen, which is inconvenient to use because it is bulky and heavy compared to the display area. Followed.

As a result, a thin film type flat panel display device having a small display area that can be easily installed and used in any place has been developed, and has gradually replaced the CRT display device.

In particular, TFT-LCD (Thin Film Transistor Liquid Crystal Display) has superior display resolution than other flat panel display devices and exhibits a faster response speed than the CRT when implementing a moving image. .

Briefly referring to the operation of the TFT-LCD, if any pixel is switched by the thin film transistor, the switched arbitrary pixel can adjust the light transmittance of the lower light source.

The switching element is mainly composed of amorphous silicon thin film transistors (a-Si: H TFTs) in which a semiconductor layer is formed of amorphous silicon. This is because the amorphous silicon thin film has a large insulation such as a low-cost glass substrate. This is because it is possible to form at a low temperature on the substrate.

In general, a liquid crystal display device uses a method of displaying an image by light emitted from a light source called a backlight located under the panel.

However, such a liquid crystal display is a very inefficient light modulator that transmits only 3-8% of the light incident by the backlight.

In view of this, various studies have been conducted on reflective liquid crystal display devices that do not use backlight light.

The reflective liquid crystal display device has a structure that reflects external light by using a material having an opaque reflective property in a pixel portion formed of a transparent electrode in a conventional transmissive liquid crystal display device.

Therefore, since the reflective liquid crystal display device is operated using natural light without a backlight, the reflective liquid crystal display device can significantly reduce the amount of power consumed by the backlight. Therefore, the reflective liquid crystal display device can be used in a portable state for a long time. There is an advantage over the display device.

On the other hand, in general, the environment in which the user uses such a reflective liquid crystal display device does not always exist natural light or an artificial light source.

That is, the reflective liquid crystal display may be used in a day when natural light is present or in an office or a building where external artificial light is present, but in a dark environment where natural light does not exist, the reflective reflective liquid crystal display device may be used. You cannot use it.

Therefore, in recent years, a semi-transmissive liquid crystal display device using a combination of advantages of a reflective liquid crystal display device using natural light and a transmissive liquid crystal display device using backlight light has been researched and developed.

1 is a schematic cross-sectional view of a thin film transistor region of a conventional reflective liquid crystal display device.

Here, only the lower substrate including the thin film transistor and the pixel region is illustrated, and the illustration is based on the case where the polycrystalline thin film transistor is employed.

Referring to FIG. 1, a lower substrate of a conventional reflective liquid crystal display device includes a plurality of data lines for applying a data signal to a source electrode 151 and a gate electrode 130 on a substrate 100 such as glass. A plurality of gate lines for applying a gate signal are formed to cross each other in a matrix form.

The area provided by the intersection of the data line and the gate line becomes a pixel area for displaying an image, and in the reflective liquid crystal display device, a reflection plate 190 is formed in the pixel area.

Next, an example of a manufacturing process for forming a polycrystalline thin film transistor and a reflecting plate having such a structure will be briefly described.

First, an amorphous semiconductor film (for example, amorphous silicon) is deposited on a substrate 100 such as glass. Then, crystallization is performed on the amorphous semiconductor film through a method such as annealing using a laser, and predetermined patterning is performed on the crystallized semiconductor film.

Thereafter, a gate insulating layer 120 having a predetermined thickness is formed on the substrate 100 and the patterned crystalline semiconductor layers 110, 111, and 112. In this case, an inorganic insulating film such as SiNx or SiOx is frequently used as the gate insulating film 120.

In addition, the gate electrode 130 is further formed at a predetermined position on the gate insulating layer 120 (corresponding to the position of the formation crystal semiconductor layer 110).

Here, AlNd may be used as the gate electrode 130, and may be formed by a deposition and patterning process through a general semiconductor process.

In this state, lightly doped impurities for forming a lightly doped drain (LDD) region are doped on the gate insulating layer 120 using the gate electrode 130 as a mask.

In this case, the gate electrode 130 corresponds to an area where the gate electrode 130 is not formed by adjusting the thickness of the gate electrode 130 and the implantation conditions of low concentration impurities so that the gate electrode 130 may serve as a mask. The low concentration impurity is doped into the crystalline semiconductor film 111 at the position (LDD region formation).

A photoresist film (not shown) is formed around the gate electrode 130 using a general semiconductor process, and a high concentration impurity for forming the source / drain regions 112 is doped.

Thereafter, the photoresist film (not shown) is removed to form a crystalline semiconductor film 110 having a source / drain region 112 and an LDD region 111 on the substrate 100, and a gate insulating layer 120. And the gate electrode 130 can be formed.

After the source / drain region 112 and the LDD region 111 are formed in this manner, an interlayer 140 is formed as a whole.

In addition, after the via hole is formed in the interlayer insulating layer 140 and the gate insulating layer 120, the source electrode 151 and the drain electrode 152 are formed to form a polycrystalline thin film transistor. .

In addition, in order to display an image in the reflective liquid crystal display, a pixel electrode serving as a reflection plate must be additionally formed.

To this end, first, a passivation layer is formed on the source / drain electrodes 151 and 152 and the interlayer insulating layer 140 of the thin film transistor. The protective film may be formed by laminating a first protective film 160 formed of a material such as SiNx and a second protective film 165 formed of an organic insulating material such as BCB.

In addition, in order to efficiently reflect light from the reflecting plate, it is preferable to form the reflecting plate in a curved irregular shape.

Therefore, in order to form an uneven reflective plate, a photosensitive resin film (for example, a polymer resin) 170 is formed on the second protective film 165 by using a spin coating method or a roll coating method.

And after aligning on the said photosensitive resin film 170 with a mask, ultraviolet-ray (arrow of drawing) is irradiated from the upper side. Subsequently, when the development process is performed, a plurality of photosensitive resin film 170 block parts having different shapes are formed on the second passivation film 165 to correspond to the shapes of the plurality of holes formed in the mask.

Thereafter, the plurality of photosensitive resin films 170 may be softened by heat treatment to form concave-convex irregularities.

The contact hole penetrates the first and second passivation layers 160 and 165 on the drain electrode 152 by a photoresist film coating / exposure / development and etching process by a general semiconductor process. ).

Thereafter, the reflective electrodes 190 are formed on the passivation layers 160 and 165 by depositing a predetermined method using a material having good reflective properties such as aluminum-based metal so as to display an image.

Accordingly, the reflective electrode 190 is electrically connected to the drain electrode 152 through the contact hole, and may perform an operation for displaying an image according to the driving of the thin film transistor.

In this manner, an array substrate of a conventional reflective and transflective liquid crystal display device can be manufactured.

However, in a conventional array substrate of reflective and semi-transmissive liquid crystal display devices having the above-described configuration, a protective film formed of an organic insulating film and an aluminum-based reflective electrode formed on the protective film generally have poor contact characteristics. As a result, peeling of the reflective electrode occurs.

Accordingly, the reflective electrode is not stably deposited on the organic insulating layer, thereby causing a problem of lowering electrical characteristics of the liquid crystal panel.

In addition, there is a problem that a large number of defects are generated when a CD (Critical Dimension) value is very large during the exposure process for depositing a reflective electrode formed on the organic insulating layer using a sputtering method and forming a pattern.

In the process of fabricating an array substrate of a liquid crystal display device, nitrogen (N ₂ ) gas is injected while depositing a reflective plate material of a metal on the organic insulating layer when the reflective plate is deposited and formed on the organic insulating layer as a protective layer. It is an object of the present invention to provide an array substrate of a reflective and semi-transmissive liquid crystal display device having a metal nitride layer formed thereon and a metal reflective electrode deposited on the metal nitride layer to improve contact characteristics of the reflective electrode.

1 is a schematic cross-sectional view of a thin film transistor region of a conventional reflective liquid crystal display device;

2 is a schematic cross-sectional view of a thin film transistor region in an array substrate of a reflective liquid crystal display device employing a polycrystalline thin film transistor according to an embodiment of the present invention.

3 is a view showing a manufacturing process for forming a polycrystalline thin film transistor and a reflector as an embodiment according to the present invention;

<Description of Signs of Major Parts of Drawings>

200 substrate 210 crystalline semiconductor film

211: LDD region 212: source / drain region

220: gate insulating film 240: interlayer insulating film

230: gate electrode 270: irregularities

251 source electrode 252 drain electrode

260: first protective film 265: second protective film

290: reflective electrode 291: aluminum layer

292: aluminum nitride layer

In order to achieve the above object, an array substrate of a liquid crystal display device according to the present invention includes a substrate; A thin film transistor including a gate electrode, a source electrode, a drain electrode, and an active layer on the substrate; A protective film made of an organic insulating film formed on the thin film transistor; And a reflective electrode electrically connected to the drain electrode and comprising a metal nitride layer formed on the passivation layer and a metal layer formed on the metal nitride layer.

The metal nitride layer and the metal layer are formed using an aluminum-based metal.

The metal nitride layer and the metal layer are formed using silver.

The metal nitride layer may be replaced with a metal oxide layer.

Reflective irregularities are formed on the protective film.

The reflective electrode is formed using a sputtering method.

In addition, to achieve the above object, an array substrate manufacturing method of a liquid crystal display device according to the present invention comprises the steps of preparing a substrate; Forming a thin film transistor including a gate electrode, a source electrode, a drain electrode, and an active layer on the substrate; Forming a passivation layer on the thin film transistor; Forming a metal nitride layer on the protective film; Forming a metal layer on the metal nitride layer; characterized in that comprises a.

The protective film is made of an organic insulating film.

In the forming of the passivation layer, the method may further include forming reflective irregularities on the passivation layer.

The metal nitride layer and the metal layer are formed using an aluminum-based metal.

The metal nitride layer and the metal layer are formed using silver.

The metal nitride layer may be replaced with a metal oxide layer.

The metal oxide layer is formed by a sputtering method using oxygen (O ₂ ) gas as a reaction gas.

In the forming of the metal nitride layer, the nitrogen (N ₂ ) gas is characterized in that the stacking by the sputtering method using a reaction gas.

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

2 is a schematic cross-sectional view of a thin film transistor region in an array substrate of a reflective liquid crystal display device employing a polycrystalline thin film transistor according to an embodiment of the present invention.

Referring to FIG. 2, a plurality of data lines for applying a data signal to a source electrode 251 and a gate electrode 230 are provided on an array substrate of a reflective liquid crystal display device on a substrate 200 such as glass. A plurality of gate lines for applying a gate signal to each other are formed in a matrix form.

The area provided by the intersection of the data line and the gate line becomes a pixel area for displaying an image, and in the reflective liquid crystal display, the reflective electrode 290 is formed in the pixel area.

In the reflective electrode 290, an aluminum nitride layer (AlN) and an aluminum (Al) layer are sequentially stacked.

Next, an example of a manufacturing process for forming a polycrystalline thin film transistor and a reflecting plate having such a structure will be briefly described with reference to FIG. 3.

3A to 3D are views illustrating a manufacturing process of forming a polycrystalline thin film transistor and a reflector in the reflective liquid crystal display according to the present invention.

Referring to FIG. 3A, an amorphous semiconductor film (eg, amorphous silicon) is deposited on a substrate 200 such as glass. Then, crystallization is performed on the amorphous semiconductor film through a method such as annealing using a laser, and predetermined patterning is performed on the crystallized semiconductor film.

Thereafter, a gate insulating film 220 having a predetermined thickness is formed on the substrate 200 and the patterned crystalline semiconductor films 210, 211, and 212. In this case, an inorganic insulating film such as SiNx or SiOx is used as the gate insulating film 220.

In addition, a gate electrode 230 is further formed to correspond to a predetermined position on the gate insulating layer 220 (the position of the formed crystal semiconductor layer 210).

Here, AlNd may be used as the gate electrode 230, and may be formed by a deposition and patterning process through a general semiconductor process.

In this state, lightly doped impurities are formed on the gate insulating layer 220 to form a lightly doped drain (LDD) region using the gate electrode 230 as a mask.

In this case, the gate electrode 230 corresponds to an area where the gate electrode 230 is not formed by adjusting the thickness of the gate electrode 230 and the implantation conditions of low concentration impurities so that the gate electrode 230 may serve as a mask. The low concentration impurity is doped into the crystalline semiconductor film 211 at the position (LDD region formation).

A photoresist film (not shown) is formed around the gate electrode 230 by using a general semiconductor process, and a high concentration of impurities for forming the source / drain regions 212 are doped.

Thereafter, the photoresist film (not shown) is removed to form a crystalline semiconductor film 210 and a gate insulating film 220 in which a source / drain region 212 and an LDD region 211 are provided on the substrate 200. And the gate electrode 230 can be formed.

After the source / drain region 212 and the LDD region 211 are formed in this manner, an interlayer 240 is formed as a whole.

In addition, after the via holes are formed in the interlayer insulating film 240 and the gate insulating film 220, the source electrode 251 and the drain electrode 252 are formed to form a polycrystalline thin film transistor. .

In addition, in order to display an image in the reflective liquid crystal display, a reflective electrode serving as a reflector should be additionally formed.

To this end, first, a passivation layer is formed on the source / drain electrodes 251 and 252 and the interlayer insulating layer 240 of the thin film transistor. Here, the protective film is formed by stacking the first protective film 260 made of a material such as SiNx.

Referring to FIG. 3B, a second passivation layer 265 formed of an organic insulating material such as BCB is laminated on the first passivation layer.

In addition, in order to efficiently reflect light from the reflecting plate, it is preferable to form the reflecting plate in a curved concave-convex shape.

Therefore, in order to form the uneven reflective plate, a photosensitive resin film (for example, a polymer resin) 270 is formed on the second protective film 265 by using a spin coating method or a roll coating method.

After aligning the photosensitive resin film 270 with a mask, ultraviolet rays (arrows in the drawing) are irradiated from above. Subsequently, when the development process is performed, a plurality of photosensitive resin film 270 block parts having different shapes are formed on the second passivation film 265 to correspond to the shapes of the plurality of holes formed in the mask.

Thereafter, the plurality of photosensitive resin layers 270 may be softened by heat treatment to form curved irregularities.

Here, the curved reflective irregularities 270 are formed on the second protective film 265 by using the photosensitive resin film. However, the reflective irregularities 270 are simultaneously formed while the second protective film 265 is formed by spin coating or the like. It is also possible.

The contact hole penetrates the first and second passivation layers 260 and 265 on the drain electrode 252 by a photoresist film coating / exposure / development and etching process by a general semiconductor process. ).

Thereafter, as illustrated in FIG. 3C, deposition is performed on the passivation layers 260 and 265 by using a material having good reflective properties such as aluminum-based metal or silver (Ag) to display an image. The reflective electrode 290 is formed.

In this case, the reflective electrode 290 is formed of an aluminum nitride (AlN) layer and an aluminum (Al) layer, and is formed by the following method.

The reflective electrode 290 is deposited on the second passivation layer 265 formed of the organic insulating layer using a metal material.

At this time, in depositing the reflective electrode 290, a sputtering method is generally used, which applies a voltage to a target side made of a material to be formed on a substrate, thereby sputtering gas in the chamber ( Mainly, Ar +) strikes a target such that atoms separated from the target accumulate on a substrate to form a thin film.

Here, nitrogen (N ₂ ) gas is injected into the reaction gas so that aluminum nitride (AlNx) is deposited on the organic insulating layer.

In another embodiment, nitrogen (N ₂ ) or oxygen (O ₂ ) gas may be injected into the reaction gas so that aluminum nitride (AlNx) or aluminum oxide (AlOx) may be stacked on the organic insulating layer.

Subsequently, as shown in FIG. 3D, only aluminum (Al) is laminated on the laminated aluminum nitride layer 291 using a sputtering method.

Thus, after forming the aluminum nitride layer 291 and the aluminum layer 292 sequentially on the organic insulating film which is the said 2nd protective layer, a patterning process is performed.

The reflective electrode formed of the aluminum layer 292 and the aluminum nitride layer 291 has excellent contact characteristics with a protective film formed of the organic insulating layer.

As described above, the array substrate of the reflective liquid crystal display device according to the present invention can be manufactured by the above-described process.

In addition, the manufacturing process as described above may also be employed in manufacturing an array substrate of a transflective liquid crystal display device.

The present invention has been described in detail with reference to specific embodiments, which are intended to specifically describe the present invention. An array substrate and a method of manufacturing the liquid crystal display device according to the present invention are not limited thereto. It will be apparent to those skilled in the art that modifications and variations are possible.

In the array substrate of the liquid crystal display according to the present invention, in forming a reflective plate by depositing a metal reflective plate material on a protective film made of an organic insulating film, nitrogen (N ₂ ) gas is injected to form a metal nitride layer and the metal nitride layer is formed on the metal nitride layer. Subsequent deposition of the reflective electrode enables pattern control of the etching CD during pattern formation, and the reflective electrode has improved contact characteristics with the organic insulating layer, thereby reducing process defects, thereby improving reliability and reducing manufacturing costs.

Claims (14)

A substrate; A thin film transistor including a gate electrode, a source electrode, a drain electrode, and an active layer on the substrate; A protective film made of an organic insulating film formed on the thin film transistor; And a reflective electrode electrically connected to the drain electrode, the reflecting electrode comprising a metal nitride layer formed on the passivation layer and a metal layer formed on the metal nitride layer. The method of claim 1, The metal nitride layer and the metal layer are formed using an aluminum-based metal, the array substrate of the liquid crystal display device. The method of claim 1, The metal nitride layer and the metal layer are formed using silver, the array substrate of the liquid crystal display device. The method of claim 1, And the metal nitride layer is replaced with a metal oxide layer. The method of claim 1, An array substrate of a liquid crystal display device, wherein reflective irregularities are formed on the passivation layer. The method of claim 1, And the reflective electrode is formed by a sputtering method. Preparing a substrate; Forming a thin film transistor including a gate electrode, a source electrode, a drain electrode, and an active layer on the substrate; Forming a passivation layer on the thin film transistor; Forming a metal nitride layer on the protective film; Forming a metal layer on the metal nitride layer; Array substrate manufacturing method of a liquid crystal display device comprising a. The method of claim 7, wherein The protective film is an organic insulating film, the array substrate manufacturing method of the liquid crystal display device. The method of claim 7, wherein The forming of the passivation layer, further comprising the step of forming the reflective irregularities on the passivation layer. The method of claim 7, wherein The metal nitride layer and the metal layer are formed using an aluminum-based metal array substrate manufacturing method of a liquid crystal display device. The method of claim 7, wherein The metal nitride layer and the metal layer are formed using silver, the array substrate manufacturing method of the liquid crystal display device. The method of claim 7, wherein And the metal nitride layer can be replaced with a metal oxide layer. The method of claim 12, And the metal oxide layer is formed by a sputtering method using oxygen (O ₂ ) gas as a reaction gas. The method of claim 7, wherein In the step of forming the metal nitride layer, a method of manufacturing an array substrate of a liquid crystal display device, characterized in that the nitrogen (N ₂ ) gas as a reaction gas is laminated by a sputtering method.