KR20020093196A - Reflective-transmissive type liquid crystal device and method of manufacturing the same - Google Patents

Abstract

PURPOSE: A transflective liquid crystal display device and a method for fabricating the same are provided to distribute transmission windows of reflecting electrodes into a plurality of areas for increasing flat topology portions below reflecting areas, thereby increasing the reflexibility and improving the uniformity of reflected light. CONSTITUTION: A transflective liquid crystal display device includes gate wires formed on a substrate having a plurality of pixel parts and extended in a first direction, data wires formed on the gate wires via a gate insulating film and extended in a second direction intersecting the first direction, a protecting film formed on the data wires and the gate insulating film, and pixel electrodes(130) formed on the protecting film and connected to the data wires through via-holes(124) formed in the protecting film on the data wires, wherein the pixel electrodes are formed of transparent electrodes and reflecting electrodes stacked on the transparent electrodes, and the reflective electrodes on the respective pixel parts have a plurality of transmission windows(136) for exposing the transparent electrodes below the reflective electrodes.

Description

Reflective-transmissive type liquid crystal device and method of manufacturing the same

The present invention relates to a reflection-transmissive liquid crystal display device and a method for manufacturing the same, and more particularly, to a reflection-transmission liquid crystal display device and a method for manufacturing the same which can increase both reflection efficiency and transmission efficiency.

In today's information society, the role of electronic display devices becomes more and more important, and various electronic display devices are widely used in various industrial fields.

In general, an electronic display device refers to a device that transmits various information to a human through vision. In other words, an electronic display device may be defined as an electronic device that converts electrical information signals output from various electronic devices into optical information signals that can be recognized by human eyes, and serves as a bridge that connects humans and electronic devices. It may be defined as.

In such an electronic display device, when an optical information signal is displayed by a light emitting phenomenon, it is called an emissive display device, and when a light modulation is displayed by reflection, scattering, or interference phenomenon, a light receiving display ( It is called a non-emissive display device. The light emitting display device, also called an active display device, includes a cathode ray tube (CRT), a plasma display panel (PDP), a light emitting diode (LED), and an electroluminescent display (electroluminescent display). display; ELD). In addition, the light receiving display device, which is a passive display device, includes a liquid crystal display (LCD), an electrochemical display (ECD), an electrophoretic image display (EPID), and the like.

Cathode ray tubes (CRTs) used in image display devices such as televisions and computer monitors occupy the highest share in terms of display quality and economy, but have many disadvantages such as heavy weight, large volume and high power consumption. .

However, due to the rapid progress of semiconductor technology, the electronic display device suitable for the new environment, that is, the thin and light, the low driving voltage and the low power consumption of the electronic device, according to the miniaturization, low voltage and low power of various electronic devices, and the miniaturization and light weight of the electronic device, The demand for flat panel display devices with features is rapidly increasing.

Among the various flat panel display devices currently developed, liquid crystal displays are thinner and lighter than other display devices, have low power consumption and low driving voltage, and are widely used in various electronic devices because they can display images close to cathode ray tubes. Is being used.

The liquid crystal display device is composed of two substrates having electrodes formed thereon and a liquid crystal layer inserted therebetween, by applying a voltage to the electrodes to rearrange liquid crystal molecules of the liquid crystal layer to control the amount of transmitted light. Display device. Electrodes are formed on each of the two substrates, and a thin film transistor (TFT) for switching a voltage applied to each electrode is formed on one of the two substrates.

Meanwhile, the liquid crystal display may be classified into a transmissive liquid crystal display displaying an image using an external light source and a reflective liquid crystal display using natural light instead of the external light source. In electronic devices such as clocks and calculators that require minimal power consumption, reflective liquid crystal displays are often used. However, transmissive liquid crystal displays are generally used in notebook computers that require high quality image display.

In the current trend, in order to realize the maximum high quality image while reducing the power consumption, it is possible to use the advantages of both the reflection type and the transmission type to obtain the appropriate visibility for the use environment despite the change in the ambient light intensity. Reflective-transmissive liquid crystal display devices have been developed.

1 is a plan view showing a pixel portion of a thin film transistor substrate (hereinafter referred to as a "TFT substrate") in a conventional reflection-transmissive liquid crystal display device. FIG. 2 is a cross-sectional view of the TFT substrate taken along the line AA ′ of FIG. 1.

1 and 2, a single metal film or a double metal such as chromium (Cr), aluminum (Al), molybdenum (Mo), or molybdenum tungsten (MoW) on a transparent substrate 10 made of glass, quartz, or sapphire A gate wiring made of a film is formed. The gate line includes a gate electrode 14, a gate line 12 connected to the gate electrode 24, and a gate pad (not shown) that receives a signal from the outside and transfers the signal to the gate line 12. .

A gate insulating layer 15 made of silicon nitride is formed on the gate line and the substrate 10. The active pattern 16 of the thin film transistor formed of a semiconductor film such as amorphous silicon is formed on the gate insulating film 15.

A data line made of a metal film is formed on the active pattern 16 and the gate insulating film 15. The data line intersects the source electrode 22, the drain electrode 24, and the gate line 12, respectively overlapping both edges of the active pattern 16, and is connected to the drain electrode 24. 20 and a data pad (not shown) connected to the end of the data line 20 to transmit an image signal.

A passivation layer 26 made of an inorganic material or an organic material is formed on the data line and the gate insulating film 15. A via hole 28 is formed through the passivation layer 26 to expose the source electrode 22. Preferably, embossing is formed on the surface of the protective film 26 to make the reflecting plate of the pixel portion into a scattering structure. Although not shown, the via hole 28 is formed on the gate pad and the data pad, respectively.

The pixel electrode 30 connected to the source electrode 22 is formed on the via hole 28 and the passivation layer 26 through the via hole 28. That is, first, a transparent electrode layer such as indium-tin-oxide (ITO) or indium-zinc-oxide (IZO) is deposited and patterned into a pixel electrode pattern to form a transparent electrode 32. Subsequently, a reflective electrode layer such as aluminum (Al) or chromium (Cr) is deposited thereon, and then the reflective electrode layer of a predetermined region is removed by a photolithography process to form a reflective electrode 34 having a transmission window 42. At this time, the region where the reflective electrode 34 remains on the transparent electrode 32 becomes the reflective region 40.

According to the above-described conventional reflection-transmissive liquid crystal display device, there is a limit in the positioning of the reflection region 40 and the topology of the reflection electrode 34 is not flat according to the step of the lower structure, so that the top surface is not flat. It is difficult to obtain reflectance of.

In addition, the color filter substrate attached on the TFT substrate has a black matrix (reference numeral 50 of FIG. 1) which prevents light leakage between the pixel portion and the pixel portion and separates the pixel portions from each other. It is formed in a mesh shape. When a misalignment occurs between the TFT substrate and the color filter substrate and the position of the black matrix is distorted, light leaks from the pixel portion, thereby greatly reducing the contrast ratio (C / R) of the panel. do. Therefore, in consideration of the assembly margin of the upper and lower substrates, the area of the transmissive region 42 must be made small, which causes a decrease in the transmissive efficiency.

It is a first object of the present invention to provide a reflection-transmissive liquid crystal display device capable of increasing both reflection efficiency and transmission efficiency.

A second object of the present invention is to provide a method of manufacturing a reflection-transmissive liquid crystal display device which can increase both reflection efficiency and transmission efficiency.

1 is a plan view showing a pixel portion of a thin film transistor substrate in a conventional reflection-transmissive liquid crystal display device.

FIG. 2 is a cross-sectional view of the thin film transistor substrate taken along the line AA ′ of FIG. 1.

3 is a plan view showing a pixel portion of a thin film transistor substrate in the reflection-transmissive liquid crystal display device according to the first embodiment of the present invention.

4 is a cross-sectional view of the thin film transistor substrate taken along line BB ′ of FIG. 3.

5A through 5D are cross-sectional views illustrating a method of manufacturing a reflection-transmissive liquid crystal display device according to a first embodiment of the present invention, taken along line BB ′ of FIG. 3.

6 is a plan view illustrating a pixel portion of a thin film transistor substrate in the reflection-transmissive liquid crystal display device according to the second embodiment of the present invention.

7 is a plan view showing a pixel portion of a thin film transistor substrate in the reflection-transmissive liquid crystal display device according to the third embodiment of the present invention.

<Explanation of symbols for main parts of the drawings>

100: transparent substrate 110: gate line

112 gate electrode 114: gate insulating film

115: active pattern 116: source electrode

118: drain electrode 120: data line

122: protective film 124: beer hall

130: pixel electrode 132: transparent electrode

134: reflective electrode

In order to achieve the first object, the present invention is a gate wiring formed on a substrate having a plurality of pixel portions and extending in a first direction; A data wiring formed on the gate wiring via a gate insulating film and extending in a second direction perpendicular to the first direction; A protective film formed on the data line and the gate insulating film; And a pixel electrode formed on the passivation layer and connected to the data line through a via hole formed in the passivation layer over the data line, wherein the pixel electrode includes a transparent electrode and a reflective electrode stacked on the transparent electrode. The reflective electrode of each pixel portion has a plurality of transmissive windows exposing the lower transparent electrodes thereof, thereby providing a reflection-transmissive liquid crystal display device.

According to an aspect of the present invention, there is provided a method including: forming a gate wiring extending in a first direction on a substrate having a plurality of pixel portions; Forming a data line extending in a second direction perpendicular to the first direction through a gate insulating layer on the gate line; Forming a protective film on the data line and the gate insulating film; Partially etching the passivation layer to form a via hole exposing the data line; And a reflection having a transparent electrode connected to the data line through the via hole on the via hole and the passivation layer, and a plurality of transmission windows stacked on the transparent electrode and exposing a transparent electrode below the one pixel part. It provides a method of manufacturing a reflection-transmissive liquid crystal display device comprising the step of forming a pixel electrode made of an electrode.

According to the present invention, it is possible to increase the reflectance by dispersing the transmission window of the reflective electrode into a plurality of regions so that the lower topology of the reflective region becomes flat. In addition, since a large number of transmission windows are formed, even if large misalignment occurs during assembly of a thin film transistor substrate (TFT substrate) and a color filter substrate, a light leakage area may be reduced in the pixel portion, thereby preventing the contrast ratio from being reduced. have.

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

3 is a plan view showing a pixel portion of a TFT substrate in the reflection-transmissive liquid crystal display device according to the first embodiment of the present invention. 4 is a cross-sectional view of the TFT substrate taken along the line BB ′ of FIG. 3.

3 and 4, a gate wiring made of a single metal film or a double metal film such as chromium (Cr), aluminum (Al), molybdenum (Mo), or molybdenum tungsten (MoW) is formed on the transparent substrate 100. do. The gate line is connected to a gate line 110 extending in a first direction (that is, a transverse direction) and a gate connected to an end of the gate line 110 to receive a scan signal from the outside and to transfer the gate signal to the gate line 110. A pad (not shown) and a gate electrode 112 of the thin film transistor that is part of the gate line 110.

A gate insulating layer 114 made of an inorganic insulator such as silicon nitride is formed on the gate line and the substrate 100. An active pattern 115 made of a semiconductor film such as amorphous silicon is formed on the gate insulating layer 114 corresponding to the gate electrode 112.

A data line made of a metal film is formed on the active pattern 115 and the gate insulating layer 114. The data line may include a first electrode (hereinafter referred to as a source electrode) 116 overlapping the first area of the active pattern 115 and a second area opposite to the first area of the active pattern 115. An overlapping second electrode (hereinafter referred to as a drain electrode) 118 and a data line 120 connected to the drain electrode 118 and extending in a second direction (ie, a longitudinal direction) perpendicular to the first direction. And a data pad (not shown) connected to an end of the data line 120 to transfer an image signal to the thin film transistor.

A passivation layer 122 having a via hole 124 exposing the source electrode 116 is formed on the data line and the gate insulating layer 114. Although not illustrated, via holes are formed on the gate pad and the data pad through the passivation layer 122. An embossing (not shown) for scattering light is formed on the surface of the passivation layer 122 in the display area, which is an area in which the pixel parts are collected to display an image.

The pixel electrode 130 connected to the source electrode 116 is formed on the passivation layer 122 through the via hole 124. Although not illustrated, a gate pad electrode and a data pad electrode connected to the gate pad and the data pad are formed on the passivation layer 122 in the same layer as the pixel electrode 130.

The pixel electrode 130 receives an image signal from a thin film transistor and generates an electric field together with an electrode (not shown) of an upper substrate (ie, a color filter substrate). The pixel electrode 130 is formed in the pixel portion partitioned by the gate line 110 and the data line 120, and an edge thereof is formed at the edge of the pixel electrode 130 to secure a high aperture ratio. Nested.

The pixel electrode 130 is a reflection in which a transparent electrode 132 such as ITO or IZO and a plurality of transmission windows 136 are formed on the transparent electrode 132 and expose a transparent electrode 132 below the pixel electrode 130. It consists of an electrode 134. Preferably, the transmission window 136 is formed in a circular shape and has an area of 10 to 90% of the area of the pixel portion.

Therefore, the TFT substrate of the reflective-transmissive liquid crystal display device of the present invention has a plurality of reflection regions R in which the reflective electrode 134 remains on the transparent electrode 132 and a plurality of transmissions in which only the transparent electrode 132 remains. Regions T are alternately arranged. That is, by forming a plurality of transmission windows 136 on the reflective electrode 34 to disperse the transmission region T into a plurality of small regions, the portion of the top surface of the reflective electrode 134 becomes flat to increase the reflectance. You can. In addition, since the reflective region R is evenly distributed in one pixel portion, uniformity of reflected light may be improved.

In addition, since a plurality of transmission windows 136 are formed, a large misalignment occurs during assembly between the TFT substrate and the color filter substrate, so that even if the position of the black matrix is changed, the area of light leakage from the pixel portion can be reduced. It is possible to reduce the contrast ratio (C / R) decrease of and improve the transmission efficiency.

5A through 5D are cross-sectional views illustrating a method of manufacturing a reflection-transmissive liquid crystal display device according to a first embodiment of the present invention, taken along line BB ′ of FIG. 3.

3 and 5A, as a gate film on a transparent substrate 100 made of an insulating material such as glass, quartz or sapphire, for example, chromium (Cr), aluminum (Al), molybdenum (Mo) or molybdenum tungsten ( After depositing a single metal film or a double metal film such as MoW), the gate film is patterned by a photolithography process to form a gate wiring. The gate line may include a gate line 110 extending in a first direction (ie, a transverse direction), a gate electrode 112 formed in the pixel portion, and a portion of the gate line 110, and an end of the gate line 110. It includes a gate pad (not shown) connected to and formed in the pad region.

A gate insulating film 114 made of an inorganic insulating film such as silicon nitride is formed on the substrate 100 on which the gate wiring is formed to a thickness of about 4500 kW. A semiconductor film such as amorphous silicon is deposited on the gate insulating layer 114 and patterned by a photolithography process to form an active pattern 115 of the thin film transistor.

After depositing a metal film such as molybdenum (Mo), molybdenum tungsten (MoW), or chromium (Cr) on the active pattern 115 and the gate insulating layer 114 by patterning the metal film by a photolithography process A data wiring is formed. The data line is connected to the source electrode 116 and the drain electrode 118 and the drain electrode 118 overlapping the first and second regions of the active pattern 115 and is orthogonal to the first direction. The data line 120 extends in two directions (ie, longitudinal directions) and a data pad (not shown) connected to an end of the data line 120 to transfer an image signal to the thin film transistor.

As the protective film 122 on the data line and the gate insulating film 114, for example, a photosensitive organic film is applied to a thickness of about 2 μm or more, and then the protective film 122 is exposed using a photomask. In this way, when the protective layer is formed by applying an organic layer thickly, parasitic capacitance is not generated between the data line and the pixel electrode to be formed thereon, so that the pixel electrode is connected to the data line 120 and the gate line in order to secure a high aperture ratio. 110 and overlapping with each other. In this case, the photomask has a partial exposure pattern made of a slit or a translucent film on a portion corresponding to the pixel portion in order to make the reflecting plate of the pixel portion scattered. When the protective film 122 is exposed using the photomask and development is performed, a via hole 124 exposing the source electrode 116 is formed. In addition, the protective film 122 of the pixel portion is formed with embossing (not shown) on its surface.

Subsequently, ITO or IZO is sputtered on the via hole 124 and the passivation layer 122 to a thickness of about 500 to 1200 GPa to form a transparent electrode layer 131. In this case, the transparent electrode layer 131 is formed to contact the source electrode 116 through the via hole 124. Subsequently, an aluminum alloy such as aluminum (Al) or aluminum admium (Al-Nd) or chromium (Cr) is deposited on the transparent electrode layer 131 to a thickness of about 1500 to 4000 GPa to form a reflective electrode layer 133. do. Then, a photoresist film 135 is applied on the reflective electrode layer 133 to a thickness of about 2 μm.

Referring to FIG. 5B, the photoresist film 135 is exposed in two steps. That is, the photoresist film 135 is exposed using a photomask in which a partial exposure pattern corresponding to the transmission region T and a complete exposure pattern corresponding to the reflective region R are formed together. Thereafter, when the photoresist film 135 is developed, the photoresist layer 135 remains thick in the reflective region R with a thickness of about 1.9 μm, and in the transmissive region T, the photoresist film 135 remains thin with a thickness of about 4000 micrometers or less by diffraction exposure. In the remaining areas, the photoresist pattern 135a from which the photoresist film is completely removed is formed.

Referring to FIG. 5C, the reflective electrode layer 133 and the transparent electrode layer 131 are simultaneously etched using the photoresist pattern 135a as an etching mask. Subsequently, the photoresist pattern 135a is ashed or dry etched to completely remove the photoresist pattern in the transmission region T to expose the reflective electrode layer 133 below the photoresist pattern. The resist pattern 135b is present.

Referring to FIG. 5D, the exposed electrode layer 133 is dry-etched using the remaining photoresist pattern 135b as an etching mask. Then, the reflective electrode layer 133 of the transmission region T is removed and only the transparent electrode layer 131 remains. Subsequently, when the photoresist pattern 135b is removed by an ashing and stripping process, a transparent window 136 stacked on the transparent electrode 132 and the transparent electrode 132 and exposing the transparent electrode 132 below is provided. A pixel electrode 130 of a reflection-transmissive liquid crystal display device including a plurality of reflective electrodes 134 is formed. Preferably, the transmission window 136 has a circular shape and is formed to have an area of 10 to 90% of the area of the pixel portion.

Here, in the present exemplary embodiment, the pixel electrode 130 of the reflection-transmissive liquid crystal display device is formed by two-step tone exposure using one photomask. However, the pixel electrode 130 may be formed using two photomasks. It is obvious. That is, after the transparent electrode layer 131 is deposited, the transparent electrode layer 131 is patterned with a first photomask to form the transparent electrode 132. Subsequently, the reflective electrode layer 133 is deposited on the transparent electrode 132 and the passivation layer 122, and then the reflective electrode layer 133 is patterned with a second photomask to expose the lower transparent electrode 132. The reflective electrode 134 having a plurality of transmission windows 136 is formed.

FIG. 6 is a plan view showing a pixel portion of a thin film transistor substrate in the reflection-transmissive liquid crystal display device according to the second embodiment of the present invention, except that the transmission window 138 of the pixel electrode 130 is formed in a polygon. Is the same as the first embodiment described above.

FIG. 7 is a plan view illustrating a pixel portion of a thin film transistor substrate in a reflection-transmission liquid crystal display device according to a third exemplary embodiment of the present invention, wherein one rectangular transmission window 140 and a plurality of circular transmission windows 142 are combined. The transmission region T of the pixel portion is formed. In addition, although not shown, a transmission region may be formed by combining one rectangular transmission window and a plurality of polygonal transmission windows.

As described above, according to the present invention, by dispersing the transmission window of the reflective electrode into a plurality of regions, the lower topology of the reflective region becomes flat. Therefore, the topology of the reflective electrode can be flattened to increase the reflectance. In addition, since the reflective regions are evenly distributed within one pixel portion, the uniformity of reflected light can be improved.

In addition, since a large number of transmission windows are formed, a large misalignment occurs during assembly between the TFT substrate and the color filter substrate, so that the area of light leakage from the pixel portion can be reduced even when the position of the black matrix is distorted. C / R) degradation can be reduced and the transmission efficiency can be improved.

As described above, although described with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified and modified within the scope of the present invention without departing from the spirit and scope of the present invention described in the claims below. It will be appreciated that it can be changed.

Claims (12)

A gate wiring formed on a substrate having a plurality of pixel portions and extending in a first direction; A data wiring formed on the gate wiring via a gate insulating film and extending in a second direction perpendicular to the first direction; A protective film formed on the data line and the gate insulating film; And A pixel electrode formed on the passivation layer and connected to the data line through a via hole formed in the passivation layer on the data line; And the pixel electrode comprises a transparent electrode and a reflective electrode stacked on the transparent electrode, wherein the reflective electrode of each pixel portion has a plurality of transmission windows exposing the lower transparent electrode. The reflection-transmissive liquid crystal display device according to claim 1, wherein the transmission window is formed in a circular or polygonal shape having the same size. The reflection-transmissive liquid crystal display device according to claim 1, wherein the transmission window is formed by combining one quadrangle and a plurality of circles. The reflection-transmissive liquid crystal display device according to claim 1, wherein the transmission window is formed by combining one quadrangle and a plurality of polygons. The reflection-transmissive liquid crystal display device according to claim 1, wherein the transmission window has an area of 10 to 90% of the area of the pixel portion. Forming a gate wiring extending in a first direction on a substrate having a plurality of pixel portions; Forming a data line extending in a second direction perpendicular to the first direction through a gate insulating layer on the gate line; Forming a protective film on the data line and the gate insulating film; Partially etching the passivation layer to form a via hole exposing the data line; And A reflective electrode having a plurality of transparent electrodes connected to the data line through the via holes on the via hole and the passivation layer, and a plurality of transmission windows stacked on the transparent electrode and exposing a transparent electrode below the one pixel part; Forming a pixel electrode comprising a reflection-transmissive liquid crystal display device. The method of claim 6, wherein the transmission window is formed in a circular or polygonal shape. The method of claim 6, wherein the transmission window is formed by combining one quadrangle and a plurality of circles. The method of claim 6, wherein the transmission window is formed by combining one quadrangle and a plurality of polygons. The method of manufacturing a reflection-transmissive liquid crystal display device according to claim 6, wherein the transmission window is formed to have an area of 10 to 90% of the area of the pixel portion. The method of claim 6, wherein the forming of the pixel electrode comprises: Sequentially depositing a transparent electrode layer and a reflective electrode layer on the via hole and the passivation layer; Forming a photoresist pattern on the reflective electrode layer so as to remain thick in the reflective region and thin in the transmissive region; Simultaneously etching the reflective electrode layer and the transparent electrode layer using the photoresist pattern as a mask; Removing the photoresist pattern by a predetermined thickness so that the reflective electrode layer of the transmission region is exposed; Removing a reflection electrode layer of the transmission region to form a plurality of transmission windows exposing the transparent electrode layer below; And And removing the photoresist pattern to form a pixel electrode composed of a transparent electrode and a reflective electrode stacked on the transparent electrode. The method of claim 6, wherein the forming of the pixel electrode comprises: Depositing a transparent electrode layer on the via hole and the passivation layer; Patterning the transparent electrode layer to form a transparent electrode connected to the data line through the via hole; Depositing a reflective electrode layer on the transparent electrode and the passivation layer; And And patterning the reflective electrode layer to form a reflective electrode having a plurality of transmission windows exposing the lower transparent electrodes.