KR100906956B1 - Trans-reflective type liquid crystal display device and method for fabricating the same - Google Patents

Abstract

Disclosed are a transflective liquid crystal display and a method of manufacturing the same. The liquid crystal display includes an upper substrate on which a color filter and a common electrode are formed on a first substrate, a switching element on a second substrate, an organic insulating layer formed on the switching element, a transparent electrode on an upper surface of the organic intercepting layer, and a pixel electrode formed on the transparent electrode. A lower substrate coupled to the upper substrate so that the common electrode and the pixel electrode face each other, and a liquid crystal layer injected between the lower substrate and the upper substrate, wherein the organic insulating layer includes a recess corresponding to the switching element; It has a convex part. Therefore, the display quality can be improved by preventing the light reflected by the transparent electrode from being irradiated to the channel portion of the switching element.

Reflective-transmissive liquid crystal display, organic insulating film, concave portion

Description

Reflective-transmissive liquid crystal display and its manufacturing method {TRANS-REFLECTIVE TYPE LIQUID CRYSTAL DISPLAY DEVICE AND METHOD FOR FABRICATING THE SAME}

1 is a cross-sectional view showing a part of a profile of a conventional reflection-transmissive liquid crystal display device.

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

FIG. 3 is an enlarged view of the circle portion shown in FIG. 2.

4A to 4F illustrate a method of manufacturing a reflection-transmissive liquid crystal display device according to an exemplary embodiment of the present invention.

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

100: upper substrate 110: second substrate

120: color filter 130: black matrix

140: common electrode 150: first alignment layer

200: lower substrate 220: thin film transistor

260: first substrate 280 organic insulating film

282: transmission electrode 283: reflection electrode

285: second alignment layer 300: liquid crystal layer

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

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

The liquid crystal display is classified into a reflective liquid crystal display device that receives an external first light and displays an image and a transmissive liquid crystal display device that receives an internally generated second light and displays an image. Recently, in order to realize high quality images while reducing power consumption, a reflection-transmissive liquid crystal display device utilizing both the advantages of the reflective liquid crystal display and the transmissive liquid crystal display has been developed.

Such a reflection-transmissive liquid crystal display displays an image in a reflection mode using the first light in a place where the external light amount is abundant, and uses a second light generated by consuming electric energy charged in itself when the external light amount is insufficient. The image is displayed in the transmission mode used.                         

FIG. 1 illustrates a part of a profile of a conventional reflection-transmissive liquid crystal display. Referring to FIG. 1, a problem of the conventional reflection-transmissive liquid crystal display 50 will be described.

First, in the reflection-transmissive liquid crystal display, the first substrate 20, the thin film transistor 10 formed on the upper surface of the first substrate 20, the organic insulating layer 30 formed on the upper surface of the thin film transistor 10, A contact hole 31 formed in the insulating film 30, a transparent electrode 32 deposited on the upper surface of the organic insulating film 30, and a pixel electrode 33 reflecting light.

In the conventional reflection-transmissive liquid crystal display device, the pattern of the organic insulating layer 30 applied to the top surface of the thin film transistor 10 is formed in a convex structure regardless of the position of the pixel. This convex structure becomes a concave structure when viewed from the backlight unit side. That is, as shown in FIG. 1, the light raised from the backlight unit is gathered in a specific direction due to irregularities formed in a concave structure. In particular, the unevenness formed on the thin film transistor channel causes light to be irradiated to the channel, thereby increasing the photo current of the thin film transistor, thereby causing a problem of deterioration of display quality of the liquid crystal display.

Accordingly, the present invention has been made in view of such a conventional problem, and an object of the present invention is to provide a liquid crystal display device for preventing a phenomenon in which some reflected light generated from the backlight unit is irradiated to the thin film transistor channel.

In addition, the present invention provides a method for manufacturing the liquid crystal display device.

According to an aspect of the present invention, a liquid crystal display device includes: an upper substrate on which a color filter and a common electrode are formed on a first substrate, a switching element on a second substrate, an organic insulating layer formed on the switching element, and an upper surface of the organic blocking layer A transparent electrode formed on the transparent electrode, a pixel electrode formed on the transparent electrode, and a lower substrate coupled to the upper substrate so that the common electrode and the pixel electrode face each other, and a liquid crystal injected between the lower substrate and the upper substrate And an organic insulating film having a concave portion corresponding to the switching element and a convex portion, wherein the concave portion is concave with respect to the upper substrate to prevent the reflected light from the transparent electrode from being irradiated to the channel portion of the switching element. It is characterized by having a shape.

In addition, the manufacturing method of the liquid crystal display device for implementing the object of the present invention, forming a color filter and a common electrode on the first substrate to form an upper substrate, forming a switching element on the second substrate, Forming an organic insulating layer having the concave and convex portions corresponding to the switching element on the second substrate, including the switching element, forming a transparent electrode on an upper surface of the organic cutting layer, and a pixel on the transparent electrode And forming an electrode.

In detail, the forming of the organic insulating layer may include coating a thin film made of an organic material on the substrate, and a portion corresponding to the convex portion may be closed on a resultant of applying the thin film, and the concave portion and the connecting portion may be Positioning a mask having an open pattern, irradiating light to a resultant product on which the mask is located, and developing the thin film to which the light is irradiated to form the organic insulating layer.

According to the present invention, concavities and convexities are concave on the thin film transistor channel so that light is not irradiated to the channel.

Hereinafter, a reflection-transmissive liquid crystal display and a method of manufacturing the same according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 2 is a profile for explaining the structure of a reflective-transmissive liquid crystal display 600 according to a preferred embodiment of the present invention, and FIG. 3 is an enlarged view specifically showing the circle portion shown in FIG.

2 and 3, the reflective-transmissive liquid crystal display according to the preferred embodiment of the present invention is generally viewed between the upper substrate 100, the lower substrate 200, the upper substrate 100, and the lower substrate 200. It is made of a liquid crystal layer 300 injected into.

The upper substrate 100 includes a color filter 120 formed of R (Red) .G (Green) .B (Blue) color pixels on the second substrate 110 and a black matrix (BM) 130. And the common electrode 140 and the first alignment layer 150 are formed.

Specifically, the second substrate 110 is formed between the RGB pixel, which is a color pixel expressed by a predetermined color by the light passing through, and each of the RGB color pixels to increase the contrast ratio (C / R). The black matrix layer 130 is formed by a thin film process. A common electrode 140 made of indium tin oxide (ITO) or indium zinc oxide (IZO) is coated thereon, and a first rubbed in a predetermined direction on the common electrode 140. An alignment layer 150 is formed.

Meanwhile, the lower substrate 200 includes a thin film transistor 220, an organic insulating layer 280, a pixel electrode formed of a transmission electrode 282, a reflective electrode 283, and a second alignment layer on the first substrate 260. A substrate 285 is formed. Here, only the thin film transistor is shown in the drawing, but the storage capacitor is not shown.

In detail, the first substrate 260, the thin film transistor 220 formed on the top surface of the first substrate 260, the organic insulating film 280 formed on the top surface of the thin film transistor 220, and the contact hole formed in the organic insulating film 280. 281, a transparent electrode 282 deposited on the upper surface of the organic insulating layer 280, and a reflective electrode 283 reflecting light.

Specifically, referring to FIGS. 2 and 3, the thin film transistor 220 is formed on the transparent first substrate 260.

The thin film transistor 220 may further include an insulating film 222 that insulates the source electrode 225 and the drain electrode 226 from the gate electrode 221, the source electrode 225 and the drain electrode 226, and the gate electrode 221. As the power is applied to the gate electrode 221, the semiconductor layers 223 and 224 are configured to supply power from the source electrode 225 to the drain electrode 226.

At least one thin film transistor 220 having such a configuration is arranged in a matrix form on the first substrate 260.

In this case, a gate power is applied to the gate electrodes of all the thin film transistors belonging to each column among the thin film transistors 220 arranged in a matrix form by a common gate line.

That is, the thin film transistors arranged in a matrix form are turned on or turned off in units of rows by a common gate line.

On the other hand, the source power of all the thin film transistors belonging to each row among the thin film transistors arranged in a matrix form is supplied with data power by a common data line.

That is, the power applied to the common data line is applied to the source electrodes of all the thin film transistors arranged in the matrix form.

As such, a turn-on voltage is applied to any one of the selected common gate lines while a desired voltage is applied to the source electrodes of all the thin film transistors, so that the thin film transistors belonging to one selected row of the thin film transistors arranged in a matrix form are sourced. Power is output from the electrode to the drain electrode via the semiconductor layer.

As such, the power output to the drain electrode drives the liquid crystal so that the display can be performed.

In this case, when a transparent electrode is formed on the drain electrode 226, the display may be performed by a transmission method. When the electrode is formed of a metal having excellent reflectance on the drain electrode 226, the display may be performed by the reflection method. In the case where both the transparent electrode and the metal electrode are formed on the drain electrode 226, the display may be performed by a reflection-transmission method.                     

In the present invention, both a transparent electrode and a metal electrode are formed on the drain electrode 226 of the thin film transistor 220 in order to perform the display in the reflection-transmission method.

In this case, the source electrode 225 is also formed on the same layer as the drain electrode 226, so that the transparent electrode and the metal electrode contact only the drain electrode 226 so as to contact the upper surface of the thin film transistor 220. The organic insulating layer 280 is formed to a thickness.

In this case, the organic insulating layer 280 has a concave portion A and a convex portion, and the concave portion A has a concave shape in order to prevent reflected light from being irradiated to the channel portion of the thin film transistor 220.

Here, the diameter of the concave portion is a diameter of the circle when a virtual circle is assumed as shown in the drawing, and the channel length C is used so that the reflected light is not irradiated to the channel portion of the thin film transistor 220. Should cover enough. Specifically, the diameter R of the concave portion preferably has a ratio of about 2: 1 with respect to the length of the channel. For example, since the channel length of most of the thin film transistors 220 is 3 µm to 5 µm, the diameter of the concave portion has a length of 6 µm to 10 µm or more, which is sufficient to cover the channel length.

Accordingly, in the reflection-transmissive liquid crystal display 600, as shown in FIG. 3, the reflected light may be irradiated to a portion other than the channel portion of the thin film transistor 220.

In the organic insulating layer 280, a contact hole 281 for opening the drain electrode 226 of the thin film transistor 220 is formed.

The pixel electrodes 282 and 283 are formed on the organic insulating layer 280 to contact the drain electrode 226 of the thin film transistor through the contact hole 281. In detail, a transparent electrode 282 made of ITO or IZO is laminated on the organic insulating layer 280 with a uniform thickness, and a reflective electrode having a transmission window 284 for opening the transparent electrode 282 over the transparent electrode 282. 283 are laminated to a uniform thickness. In this case, a metal material having excellent reflectance is used for the reflective electrode 283.

In this case, since the transparent electrode 282 is stacked on the organic insulating layer 280 with a uniform thickness, the transparent electrode 282 has the same structure as the organic insulating layer 280. That is, since the shape of the organic insulating layer 280 has a concave-convex structure having convex and concave shapes as described above, the shape of the transparent electrode 282 is also the same.

Thereafter, the reflective electrode 283 stacked on the transparent electrode 282 has the same surface structure as the transparent electrode 282 because it is stacked with a uniform thickness. The second alignment layer 285 is further formed on the reflective electrode 283 and the transmission window 284.

Next, the upper substrate 100 is coupled to face the lower substrate 200 so that the common electrode 140 faces the pixel electrodes 282 and 283. As such, the liquid crystal layer 300 is injected between the upper substrate 100 and the lower substrate 200. Thus, the reflection-transmissive liquid crystal display device 600 is completed.

Hereinafter, a manufacturing process of the lower substrate 200 of the reflection-transmissive liquid crystal display 600 shown in FIG. 2 will be described.                     

4A to 4F illustrate a more specific manufacturing method of a reflection-transmissive liquid crystal display device according to an exemplary embodiment of the present invention. Here, the same parts among the parts shown in FIG. 1 use the same reference numerals.

Referring to FIG. 4A, a gate thin film 230 having a predetermined thickness is formed through a sputtering process or the like over the entire area of the transparent first substrate 260.

In this case, the material forming the gate thin film 230 may be aluminum (Al), aluminum-neodymium alloy (Al-Nd alloy), chromium (Cr) and the like.

In the case of using pure aluminum as the gate thin film 230, troubles such as hill rock may occur if the process temperature is not carefully set.

 As such, when the gate thin film 230 using aluminum-neodymium alloy and chromium is used, the gate electrode 221 having low electrical resistance and high strength can be obtained.

Referring to FIG. 4B, the gate thin film 230 formed on the first substrate 260 is patterned through a photoresist coating process, a photo process using a first pattern mask (not shown), an exposure process, and an etching process. The electrode 221 is formed.

Subsequently, as shown in FIG. 4C, thin films are continuously deposited on the first substrate 260 by a plasma enhanced chemical vapor deposition process to include the gate electrode 221.

Specifically, the thin films sequentially deposited on the first substrate 100 on which the gate electrode 221 is formed may include the gate insulating layer 222, the first and second semiconductor layers 223 and 224, and the metal for forming the source / drain electrodes. Film 227.

More specifically, the gate insulating layer 222 is a transparent thin film formed on the entire surface of the first substrate 260 to include the gate electrode 221 and has a thin film thickness of about 4500 kPa made of silicon nitride (SiNx).

On the other hand, the first semiconductor film 223 is formed over the entire surface of the gate insulating film 222. The first semiconductor film 223 is formed of amorphous silicon and has a thickness of about 2000 GPa.

When power is applied to the gate electrode 221, the first semiconductor layer 223 serves as a channel for supplying power to the drain electrode from the source electrode to be described later.

Subsequently, the second semiconductor film 224 is formed over the entire surface of the first semiconductor film 223. The second semiconductor film 224 is formed such that the n + amorphous silicon material in which the n + material is ion-doped to the amorphous silicon has a thickness of about 500 GPa.

On the other hand, the source-drain electrode forming metal film 227 is again formed on the upper surface of the second semiconductor film 224. The source-drain electrode forming metal film 227 has a thickness of about 1500 GPa by the sputtering method. Is formed.

Subsequently, as illustrated in FIG. 4D, the gate insulating layer 222, the first and second semiconductor layers 223 and 224, and the source / drain electrode forming metal layer 227 formed on the upper surface of the gate electrode 221 are predetermined. Patterned to shape.

Subsequently, the second semiconductor film 224 exposed to the outside in the process of forming the drain electrode 225 and the source electrode 226 is etched using the source electrode 226 and the drain electrode 225 as a mask to form a thin film transistor ( 220) is produced.

In addition, the organic insulating layer 280 is thinly formed on the entire surface of the first substrate 260 on which the thin film transistor 220 is formed.

The organic insulating layer 280 is intended to prevent the transmissive electrode and the reflective electrode, which will be described later, from shorting to a conductive pattern other than the drain electrode 225, for example, the source electrode 226 and the like. In this case, the organic insulating layer 280 should be insulative and transparent so that light can be transmitted therethrough. In order to satisfy this, the organic insulating layer 280 is made of a benzo cyclic butene material, which is a transparent insulating material.

Thereafter, as shown in FIG. 4E, a mask for forming irregularities of the organic insulating layer 280 is positioned. The mask 700 has a portion 710 corresponding to the thin film transistor is opened, and the remaining portion has a slit opened in a predetermined pattern. A portion of the organic insulating layer 280 corresponding to the thin film transistor 220 may have a concave shape, and other portions of the organic insulating layer 280 may have a convex shape. That is, in order to implement a concave shape, a mask 700 having a slit that opens a central portion widely and gradually closes to a peripheral portion thereof is required.

Subsequently, as shown in FIG. 4F, the mask 700 is positioned, and the organic insulating layer 280 is unevenly formed through a process of exposure and development.

In order to have a gentle concave shape in the portion of the organic insulating layer 280 corresponding to the thin film transistor 220, the slit of the mask 700 of FIG. 4E must be precisely implemented.                     

Here, the ratio of the diameter of the channel portion of the thin film transistor 220 to the concave portion of the organic insulating layer 280 is preferably set to about 1: 2.

Although the subsequent steps are not shown in the drawings, a photoresist thin film having a predetermined thickness is formed on the top surface of the organic insulating film by spin coating, and the like, corresponding to the drain electrode portion of the thin film transistor in the photoresist thin film by a photo / etch process. The contact portion is removed to form a contact hole.

Subsequently, a transparent electrode is deposited on the organic insulating layer to have a predetermined thickness of a conductive ITO material or an IZO material. At this time, part of the transmissive electrode is also deposited on the transistor of the thin film transistor exposed by the context hole, and the power output from the drain electrode is applied.

This transmissive electrode is formed on the upper surface of the organic insulating film in order to cause the reflection-transmissive liquid crystal display to perform display in the transmissive mode.

Thereafter, a reflective electrode is formed on the upper surface of the organic insulating film by a sputtering method.

As a result, the light supplied from the outside is reflected by the unevenness of the reflective electrode and passes through the liquid crystal to enable high brightness display, and the display is possible by using the light passing through the transmissive electrode through the organic insulating layer on the bottom surface of the lower substrate.

The lower substrate manufactured by the above method is combined with the upper substrate on which the RGB pixel and the common electrode are formed, and the liquid crystal is injected between the first and second substrates while the upper substrate and the lower substrate are coupled to each other so that the reflection-transmissive liquid crystal is formed. The display device is manufactured.

As described above in detail, since the portions corresponding to the thin film transistors have the concave-convex shape of the organic insulating film applied to the upper surface of the thin film transistor in a concave structure when viewed from the upper substrate, the partial reflection light of the light generated from the backlight unit is thin film transistor channel portion. Can be prevented.

As mentioned above, although this invention was demonstrated by the said Example, this invention is not restrict | limited by this, It is clear that a deformation | transformation and improvement are possible for a person skilled in the art within the range of ordinary knowledge.

Claims (6)

An upper substrate on which a color filter and a common electrode are formed on the first substrate; A switching element on the second substrate, an organic insulating layer formed on the switching element, a transparent electrode formed on an upper surface of the organic switching layer, and a pixel electrode formed on the transparent electrode, wherein the common electrode and the pixel electrode face each other. A lower substrate coupled with the upper substrate; And A liquid crystal layer injected between the lower substrate and the upper substrate, The organic insulating layer has a concave portion corresponding to the switching element and a convex portion, wherein the concave portion has a concave shape with respect to the upper substrate in order to prevent the reflected light from the transparent electrode from being irradiated to the channel portion of the switching element. Liquid crystal display device. 2. The liquid crystal display device according to claim 1, wherein the ratio of the channel length of the switching element to the diameter of the concave portion is about 1: 2. The liquid crystal display device according to claim 1, wherein the thickness of the organic insulating film of the concave portion is thinner than the thickness of the organic insulating film of the convex portion and thinner than the thickness of the organic insulating film of the region where the pixel electrode is formed. Forming an upper substrate by forming a color filter and a common electrode on the first substrate; Forming a switching element on the second substrate; Forming an organic insulating layer including the switching element, the organic insulating layer having concave and convex portions corresponding to the switching element on the second substrate; Forming a transparent electrode on an upper surface of the organic barrier film; And Forming a pixel electrode on the transparent electrode. The method of claim 4, wherein Forming the organic insulating film, Coating a thin film made of an organic material on the substrate; Positioning a mask having a pattern in which a portion corresponding to the convex portion is closed and the concave portion and the connecting portion are opened on the resultant product to which the thin film is applied; Irradiating light onto the resultant product in which the mask is located; And And developing the thin film irradiated with the light to form the organic insulating layer. The method of claim 4, wherein the ratio of the channel length of the switching element to the diameter of the concave portion is about 1: 2.

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