Liquid crystal display device and method for manufacturing the same

An LCD device includes first and second substrates; an insulating layer on the first substrate, the insulating layer comprising an inclined sidewall portion exposing a portion of the first substrate; gate and data lines crossing each other and defining pixel region on the first substrate; a common auxiliary electrode on the inclined sidewall portion of the insulating layer; a pixel electrode on the first substrate; a common electrode on the second substrate; and a liquid crystal layer between the first and second substrates.

This application claims the benefit of the Korean Application No. P2002-41003 filed on Jul. 13, 2002, which is hereby incorporated by reference for all purposes as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display (LCD) device and a method of fabricating the same. More particularly, the present invention relates to a liquid crystal display device and a method for fabricating the same having a common auxiliary electrode capable of preventing electric field dispersion, stabilizing the alignment of liquid crystal material, and wherein an aperture ratio of the LCD device is increased.

2. Discussion of the Related Art

Over time, demands on display technology have gradually increased and resulted in the development of a variety of flat display panels including liquid crystal displays (LCDs), plasma display panels (PDPs), electro luminescent displays (ELDs), vacuum fluorescent displays (VFDs), etc. Some of the aforementioned flat panel display panels are currently being employed as displays of various apparatuses.

Owing to their excellent picture display quality, light weight, thin dimensions, and low power consumption, LCDs are being developed for use as televisions (TVs), capable of receiving and displaying broadcasted signals, and are widely used in portable displays as monitors of notebook computers and the like.

Despite various technical developments in the LCD technology, however, research in enhancing picture quality of LCD devices has been lacking in some respects compared to research in other features and advantages of LCD devices. Therefore, to increase the use of LCD devices as displays in various fields of application, LCD devices capable of expressing high quality images (e.g., images having a high resolution and a high luminance) with large-sized screens, while still maintaining a light weight, minimal dimensions, and low power consumption must be developed.

LCDs generally include a liquid crystal display panel for displaying a picture and a driving part for providing driving signals to the liquid crystal display panel. The LCD panel generally includes first and second glass substrates bonded to each other and spaced apart from each other by a cell gap. A layer of liquid crystal material is injected into the gap between the first and second glass substrates. Light transmittance characteristics of the liquid crystal material may be selectively altered by electric fields generated between the first and second glass substrates to display images on the LCD panel.

Molecules of liquid crystal material contained between upper and lower substrates of Twisted Nematic (TN) mode LCDs are aligned along longitudinal directions substantially parallel with the lower and upper substrates and are generally spirally twisted to a predetermined pitch such that the alignment of the longitudinal directions within the liquid crystal molecules is continuously changeable.

The light transmittance characteristics of TN mode LCDs generally varies across each gray level in accordance with a corresponding viewing angle. Further, TN mode LCDs distribute light symmetrically in right and left directions while distributing light asymmetrically in lower and upper directions. Accordingly, gray inversion of images is generated.

Use of Vertical Alignment (VA) mode LCDs has been proposed to overcome the aforementioned problems and compensate for variations in light transmittance characteristics across viewing angles. In VA mode LCDs, a pixel region is divided into a plurality of domains, wherein liquid crystal material aligned in different directions in each of the domains. In VA mode LCDs either a protrusion or an electric field inducing window is formed on the upper substrate while a common auxiliary electrode (i.e., side electrode) is formed on the lower substrate.

A related art LCD device will now be explained in greater detail below.

FIG. 1illustrates a schematic view of a related art LCD device andFIG. 2illustrates a cross-sectional view of the related art LCD device shown inFIG. 1taken along line I-I′.

A related art LCD device generally includes opposing lower and upper substrates1and10and a layer of liquid crystal material16interposed between the lower and upper substrates1and10.

The lower substrate1includes a plurality of gate lines2and data lines4crossing each other, pixel regions defined at each of the crossings of the gate and data lines2and4, a gate electrode (not shown) extending to both sides of the gate line2, a gate insulating layer (not shown) formed over the lower substrate1and on the gate line2, an active region3formed over the gate insulating layer in a region above the gate line2, a pixel electrode7formed within the pixel region and formed out of the same layer as that of the active region3, a source electrode4aextending from the data line4and overlapping a first portion of the active region3, a drain electrode4bformed apart from the source electrode4aand overlapping a second portion of the active region3as well as a predetermined portion of the pixel region7, an interlayer passivation film6formed over an entire surface of the lower substrate1and on the pixel electrode7, an orientation control electrode5formed over the interlayer passivation film6and overlapping the circumference of the pixel electrode7, and a first alignment layer8formed over the lower substrate1and on the orientation control electrode5. Orientation control electrodes5of adjacent pixel regions are connected to each other.

The upper substrate10includes a black matrix layer (not shown) for preventing light leakage in regions outside the pixel regions of the lower substrate1, a color filter layer (not shown) formed in regions over the upper substrate10corresponding to the black matrix layer and the pixel regions of the lower substrate1, a common electrode13formed over the color filter layer wherein the common electrode13has an “X”-shaped orientation control window14, and a second alignment layer15formed over the upper substrate10and on the common electrode13.

Referring toFIG. 2, when an electric field is generated between the pixel electrode7and the common electrode13, a fringe field (designated by the solid arrows) is generated by the orientation control window14within the common electrode13. Affected by the fringe field, liquid crystal molecules become aligned differently at opposing sides of the orientation control window14and, accordingly, compensate for variations in light transmittance characteristics across viewing angles.

Use of LCD devices such as those illustrated inFIGS. 1 and 2is disadvantageous for the following reasons. For example, the orientation control electrode5is formed of an opaque metal and is spaced apart from the data line4by a predetermined distance to prevent the generation of an electrical short. Because the orientation control electrode5is spaced apart from the data line4, a width of the pixel region decreases thereby decreasing aperture ratio and luminance of the LCD device. To compensate, the related art LCD devices illustrated inFIGS. 1 and 2require backlights of increased brightness and therefore require an increased level of power consumption.

Moreover, electrical fields generated in TN mode LCD devices face outwardly toward the perimeter of the pixel. Accordingly, alignment of the liquid crystal material becomes unstable and light leakage is generated at the perimeter of each pixel region, decreasing the overall brightness of the LCD device. Furthermore, alignment of the liquid crystal material becomes unstable when a light force is applied the LCD panel and a spot is generated that is difficult to remove due to a slow response time of the liquid crystal material.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a liquid crystal display device and method of fabricating the same that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.

An advantage of the present invention provides an LCD device and a method of fabricating the same wherein an alignment of liquid crystal material is stable and a rapid response time and high aperture ratio may be obtained.

To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, an LCD device may, for example, include first and second substrates; an insulation layer on the first substrate, the insulation layer having an inclined sidewall portion exposing a portion of the first substrate; a plurality of gate and data lines crossing each other to define pixel regions on the first substrate; a common auxiliary electrode on the inclined sidewall portion of the insulation layer; a pixel electrode on the first substrate; a common electrode on the second substrate; and a liquid crystal layer between the first and second substrates.

In one aspect of the present invention, a method for manufacturing an LCD device may, for example, include providing a first substrate; providing a second substrate; forming an insulation layer on a first substrate, wherein the insulation layer comprises an inclined sidewall portion exposing a portion of the first substrate; forming gate and data lines to cross each other on the insulation layer; forming a common auxiliary electrode on the inclined sidewall portion of the insulation layer; forming a passivation layer and a pixel electrode on the first substrate; and forming a common electrode on the second substrate.

In another aspect of the present invention, a method for manufacturing an LCD device may, for example, include providing a first substrate; forming an insulation layer on the first substrate, the insulation layer having an inclined sidewall portion exposing a portion of the first substrate; forming a gate line along a first direction on the insulation layer and a common auxiliary electrode on the inclined sidewall portion of the insulation layer; forming a gate insulating layer on the first substrate; forming a data line along a second direction on the gate insulating layer, the second direction being substantially perpendicular to the first direction; forming a passivation layer on the first substrate; and forming a pixel electrode on the first substrate.

In yet another aspect of the present invention, a method for manufacturing an LCD device may, for example, include providing a first substrate; forming an insulation layer on the first substrate; forming a gate line on the insulation layer in one direction; forming a gate insulating layer on the gate line; etching the gate insulating layer and the insulation layer to form inclined sidewall portion; forming a data line on the gate insulating layer and a common auxiliary electrode on the inclined sidewall portion of the insulation layer; forming a passivation layer on the first substrate; and forming a pixel electrode on the first substrate.

DETAILED DESCRIPTION OF THE INVENTION

According to the principles of the present invention, an LCD device may, for example, include a common auxiliary electrode (i.e., a side electrode) formed on an inclined sidewall portion of an insulation layer formed on a lower substrate. Accordingly, alignment efficiency of liquid crystal material may be improved and a dispersion of alignment directions of liquid crystal molecules may be prevented such that alignment directions of liquid crystal molecules may be stabilized. According to the principles of the present invention, the common auxiliary electrode may be simultaneously formed with the forming of a gate line or a data line.

Accordingly, common auxiliary electrodes and methods for manufacturing the same will now be described in greater detail.

According to the principles of the present invention, a common auxiliary electrode may be formed on an inclined sidewall portion of an organic insulation layer of a lower substrate. In a first aspect of the present invention, the common auxiliary electrode may be formed simultaneously with a formation of the gate line. In a second aspect of the present invention, the common auxiliary electrode may be formed simultaneously with a formation of the data line.

FIG. 3illustrates a schematic view of a unit pixel of an LCD device according to the principles of the present invention.FIG. 4illustrates a cross-sectional view of the LCD device shown inFIG. 3taken along line II-II′ according to a first aspect of the present invention.

Referring toFIGS. 3 and 4, the LCD device according to the first aspect of the present invention may, for example, include opposing lower and upper substrates50and40, respectively, spaced apart from each other by a predetermined distance and a layer of liquid crystal material45interposed between the lower and upper substrates50and40. As will be described in greater detail below, the lower substrate50may, for example, include a plurality of gate lines and data lines52aand54a, respectively, formed to cross each other and defining pixel regions where they cross. Further, as will be described in greater detail below, a pixel electrode56may be formed within each pixel region. Although not shown, a thin film transistor (TFT) may be formed at crossings of the gate and data lines52aand54a. The TFT may be used as a switch capable of transmitting signals applied to the data line54ato the pixel electrode56in response to a signal applied to the gate line52a.

According to the first aspect of the present invention, an organic insulation layer51having an inclined sidewall portion may be formed on the lower substrate50such that the inclined sidewall portion exposes the lower substrate50in regions of the lower substrate corresponding to the pixel regions. In one aspect of the present invention, the organic insulation layer51may be formed out of an organic insulating material such as BenzoCycloButene (BCB), or photo-acrylic resin, and the like. The gate line52amay be formed on the organic insulation layer51along a first direction and a common auxiliary electrode52bmay be formed on the inclined sidewall portion of the organic insulation layer51and overlap at least a portion of the perimeter of the pixel electrode56. A gate insulating layer53may be formed over the entire surface of the lower substrate50and on the gate line52aand the common auxiliary electrode52b. A data line54amay be formed on the gate insulating layer53to substantially perpendicularly cross the gate line52a. A passivation layer55may be formed over the entire surface of the lower substrate50including the data line54a. The pixel electrode56may be formed on the passivation layer55within the pixel region.

According to the first aspect of the present invention, the upper substrate40may, for example, include a black matrix layer41for preventing light leakage in regions outside the pixel regions of the lower substrate50. The upper substrate40may also include a color filter layer42for selectively transmitting light having predetermined wavelengths at portions corresponding to pixel regions of the black matrix layer41. A common electrode43may be formed over the entire surface of the upper substrate40and on the color filter layer42. Further, at least one dielectric protrusion44may be formed on a portion of the common electrode43in a pattern substantially symmetric about the center of the pixel region.

Referring toFIG. 4, when an electric field is formed between the pixel electrode56on the lower substrate50and the common electrode43on the upper substrate40, the dielectric protrusion44, formed on the common electrode43of the upper substrate40, induces a fringe field (designated by the dotted lines of FIG.4). The dielectric protrusion44distorts the electric field applied to the layer of liquid crystal material45. Due to the presence of the fringe field, liquid crystal molecules may be asymmetrically aligned with respect to the dielectric protrusion44and light transmittance characteristics of the liquid crystal material may be compensated for across a range of viewing angles. Accordingly, the dielectric protrusion44uniformly stabilizes an image within the pixel region and generates a multi-domain effect within the LCD device. In one aspect of the present invention, at least one dielectric protrusion44may be formed on the common electrode43of the upper substrate40. According to the principles of the present invention, an electric field inducing window may be provided as a hole or slit within the common electrode43as an alternative to forming the dielectric protrusion44on the common electrode43.

According to the principles of the present aspect, the fringe field may be reinforced by the common auxiliary electrode52boverlapping at least a portion of the perimeter of the pixel electrode56. As a result of the reinforcement, liquid crystal molecules may be prevented from facing outwardly at the perimeter of the pixel electrode56such that liquid crystal molecules are uniformly aligned. Due to the presence of the common auxiliary electrode52b, the area of the pixel region affected by the electric field increases. As a result, the LCD device of the first aspect of the present invention may have an increased aperture ratio compared to aperture ratios of LCD devices such as those illustrated inFIGS. 1 and 2. Further, the efficiency with which liquid crystal molecules at the perimeter of the pixel electrode56may be driven increases. As a result, the time required for the layer of liquid crystal material45to stabilize within the LCD device, and therefore the response time, may be reduced compared to stabilization and response times of LCD devices such as those illustrated inFIGS. 1 and 2.

A method for manufacturing the LCD device according to the first aspect of the present invention will now be described in greater detail.

FIGS. 5Ato5D illustrate cross-sectional views in fabricating the LCD device shown inFIG. 3taken along line II-II′ according to a first aspect of the present invention.

A method for fabricating the lower substrate50will now be described.

Referring toFIG. 5A, an organic insulation layer51may be formed on the lower substrate50and selectively etched to expose portions of the lower substrate50in regions corresponding to the pixel region and to form an inclined sidewall portion in the organic insulation layer51. In one aspect of the present invention, the organic insulation layer51may be formed out of an organic insulating material such as BenzoCycloButene (BCB), photo-acrylic resin, and the like.

Next, a first metal layer52may be formed over the entire surface of the lower substrate50and on the organic insulation layer51. In one aspect of the present invention, the first metal layer may be formed by a sputtering process.

Referring toFIG. 5B, the first metal layer52may be selectively patterned to form a gate line52aarranged along a first direction, wherein the gate line includes a gate pad (not shown) and a gate electrode (not shown), and a common auxiliary electrode52bon the inclined sidewall portion of the organic insulation layer51and substantially surrounding the pixel region. In one aspect of the present invention, the first metal layer52may be formed of a material such as Al, Mo, Cr, Ta Al alloy, and the like.

Next, a gate insulating layer53may be deposited over the entire surface of the lower substrate50and on the gate line52aand common auxiliary electrode52b. In one aspect of the present invention, the gate insulating layer53may be formed of a material such as SiNx, SiOx, and the like, by a deposition method such as Plasma Enhanced Chemical Vapor Deposition (PECVD). In another aspect of the present invention, the gate insulating layer53may be formed of a material such as BenzoCycloButene (BCB), acrylic resin, polyimide compound, and the like, to obtain an LCD device having an increased high aperture ratio.

Although not shown, first and second semiconductor layers (e.g., amorphous silicon and impurity doped amorphous silicon layers) may be formed over the entire surface of the lower substrate50to form an active layer (not shown). The first and second semiconductor layers may then selectively patterned using a mask to be formed into an island-shaped active layer (not shown) above the gate electrode.

Referring toFIG. 5C, a second metal layer may be formed over the entire surface of the lower substrate50and on the active layer (not shown) and selectively patterned to form the data line54a(shown inFIG. 3) arranged along a second direction, substantially perpendicular to the first direction, to define the pixel region, wherein the data line includes data pads (not shown) arranged at opposing ends of the data line54a. In one aspect of the present invention, the second metal layer may be formed out of a material such as Al, Mo, Cr, Ta, Al alloy, and the like, by a deposition method such as sputtering.

Although not shown, a source electrode may be formed to extend from the data line54atoward the active layer, and a drain electrode (not shown) may be formed to be spaced apart from the source electrode. During the patterning of the second metal layer54, the second semiconductor layer may become over-etched between the source and drain electrodes.

After patterning the second metal layer, a passivation layer55may be, formed over the entire surface of the lower substrate50and on the data line54a. In one aspect of the present invention, the passivation layer55may be formed out of a material such as BenzoCycloButene (BCB), acrylic resin, polyimide compound, SiNx, or SiOx, and the like. After being formed over the lower substrate50, the passivation layer55may be selectively etched using a photo-mask process to form so that first, second, and third contact holes (not shown) above the drain electrode, the gate pad, and the data pad, respectively.

Next, a transparent conductive metal layer may be formed over the passivation layer55and within the first, second, and third contact holes. Accordingly, a portion of the transparent conductive metal layer provided in the pixel region (i.e., the pixel electrode56) electrically contacts the drain electrode through the first contact hole, a portion of the transparent conductive metal layer provided on the passivation layer and adjacent the second contact hole (i.e., gate pad terminal) may contact the gate pad, and a portion of the transparent conductive metal layer provided on the passivation layer and adjacent the third contact hole (i.e., data pad terminal) may contact the date pad. In one aspect of the present invention, the pixel electrode56may be formed to overlap with at least a portion of the common auxiliary electrode52bformed on the inclined sidewall portion of the organic insulation layer51.

A method for fabricating the upper substrate40will now be described.

Referring toFIG. 5D, a layer of black matrix material may be formed over the upper substrate40and then patterned to form a black matrix layer41.

Next, a color filter layer42may be formed over the upper substrate40and on the black matrix layer41. In one aspect of the present invention, the color filter layer42may comprise red, green, and blue (R, G, and B) elements formed in regions corresponding to respective pixel regions.

Next, a common electrode43may be formed over the entire surface of the upper substrate40and on the color filter layer42. In one aspect of the present invention, the common electrode43may be formed out of a transparent conductive material such as ITO.

Subsequently, a photosensitive material may be formed over the common electrode43and selectively patterned by photolithography to form at least one dielectric protrusion44. According to the principles of the present invention, the dielectric protrusion44may distort electric fields applied to the layer of liquid crystal material45. In one aspect of the present invention, the dielectric protrusion44may be formed of a photosensitive material having a dielectric constant substantially equal to or less than the dielectric constant of the liquid crystal material. For example, the dielectric protrusion44may be formed out of a material having the dielectric constant of about 3 or less. Accordingly, the dielectric protrusion44may be formed out of a material such as photoacrylate, BenzoCycloButene (BCB), and the like. In another aspect of the present invention, an electric field inducing window (not shown) may be provided as a hole or slit within the common electrode43as an alternative to forming the dielectric protrusion44.

Next, a spacer (not shown) and sealant material may be formed on one of the lower and upper substrates50and40followed by bonding of the lower and upper substrates50and40together. Subsequently, liquid crystal material may be injected between the lower and upper substrates50and40, thereby forming a layer of liquid crystal material45. In one aspect of the present invention, the liquid crystal material may have either a positive or negative dielectric anisotropy. In another aspect of the present invention, a chiral dopant may be added to the liquid crystal material45.

In a second aspect of the present invention, a common auxiliary electrode may be formed on an inclined sidewall portion of an organic insulation layer of a lower substrate. Further, the common auxiliary electrode may be formed simultaneously with a formation of the data line.

FIG. 6illustrates a cross-sectional view of an LCD device shown inFIG. 3taken along line III-III′ according to the second aspect of the present invention.

Referring toFIGS. 3 and 6, the LCD device according to the second aspect of the present invention may, for example, include opposing lower and upper substrates50and40, respectively, spaced apart from each other by a predetermined distance and a layer of liquid crystal material45interposed between the lower and upper substrates50and40. As will be described in greater detail below, the lower substrate50may, for example, include a plurality of gate and data lines52aand54a, respectively, formed to cross each other and defining pixel regions where they cross. Further, and as will be discussed in greater detail below, a pixel electrode56may be formed within each pixel region. Although not shown, a thin film transistor (TFT) may be formed at crossings of the gate and data lines52aand54a. The TFT may be used as a switch capable of transmitting signals applied to the data line54ato the pixel electrode56in response to a signal applied to the gate line52a.

According to the second aspect of the present invention, an organic insulation layer51having an inclined sidewall portion may be formed on the lower substrate50such that the inclined sidewall portion exposes the lower substrate50in regions of the lower substrate50corresponding to the pixel regions. In one aspect of the present invention, the organic insulation layer51may be formed out of an organic insulating material such as BenzoCycloButene (BCB), or photo-acrylic resin, and the like. The gate line52amay be formed on the organic insulation layer51along a first direction and a gate insulating layer53may be formed over the entire surface of the lower substrate50and on the gate line52a. A data line54amay be formed over the gate insulating layer53to substantially perpendicularly cross the gate insulating layer53and a common auxiliary electrode54bmay be formed on the inclined sidewall portion of the organic insulation layer51and overlap at least a portion of the perimeter of the pixel electrode56. A passivation layer55may be formed over the entire surface of the lower substrate50and on the data line54aand the common auxiliary electrode54b. The pixel electrode56may be formed on the passivation layer55within the pixel region.

According to the second aspect of the present invention, the upper substrate40may, for example, include a black matrix layer41for preventing light leakage in regions outside the pixel regions of the lower substrate50. The upper substrate40may also include a color filter layer42for selectively transmitting light having predetermined wavelengths at portions corresponding to pixel regions of the black matrix layer41. A common electrode43may be formed over the entire surface of the upper substrate40and on the color filter layer42. Further, at least one dielectric protrusion44may be formed on a portion of the common electrode43in a pattern substantially symmetric about the center of the pixel region.

Referring toFIG. 6, when an electric field is formed between the pixel electrode56on the lower substrate50and the common electrode43on the upper substrate40, the dielectric protrusion44, formed on the common electrode43of the upper substrate40, induces a fringe field (designated by the dotted lines of FIG.6). The dielectric protrusion44distorts the electric field applied to the layer of liquid crystal material45. Due to the presence of the fringe field, liquid crystal molecules may be asymmetrically aligned with respect to the dielectric protrusion44and light transmittance characteristics of the liquid crystal material may be compensated for across a range of viewing angles. Accordingly, the dielectric protrusion44uniformly stabilizes an image within the pixel region and generates a multi-domain effect within the LCD device. In one aspect of the present invention, at least one dielectric protrusion44may be formed on the common electrode43of the upper substrate40. According to the principles of the present invention, an electric field inducing window may be provided as a hole or slit within the common electrode43as an alternative to forming the dielectric protrusion44on the common electrode43.

According to the principles of the present invention, the fringe field may be reinforced by the common auxiliary electrode54boverlapping at least a portion of the perimeter of the pixel electrode56. As a result of the reinforcement, liquid crystal molecules may be prevented from facing outwardly at the perimeter of the pixel electrode56such that liquid crystal molecules are uniformly aligned. Due to the presence of the common auxiliary electrode52b, the area of the pixel region affected by the electric field increases. As a result, the LCD device of the first aspect of the present invention may have an increased aperture ratio compared to aperture ratios of LCD devices such as those illustrated inFIGS. 1 and 2. Further, the efficiency with which liquid crystal molecules at the perimeter of the pixel electrode56may be driven increases. As a result, the time required for the layer of liquid crystal material45to stabilize within the LCD device, and therefore the response time, may be reduced compared to stabilization and response times of LCD devices such as those illustrated inFIGS. 1 and 2.

A method for manufacturing the LCD device according to the second aspect of the present invention will now be described in greater detail.

FIGS. 7Ato7D illustrate cross-sectional views in fabricating the LCD device shown inFIG. 3taken along line III-III′ according to a second aspect of the present invention.

Referring toFIG. 7A, the organic insulation layer51and the first metal layer52may be successively formed over the entire surface of the lower substrate50. In one aspect of the present invention, the first metal layer52may be formed of a material such as Al, Mo, Cr, Ta, Al alloy, or the like and may be deposited by sputtering process. Next, the first metal layer52may be selectively patterned to form a gate line52a(as shown inFIG. 3) arranged along a first direction, a gate pad having a predetermined area at one end of the gate line52a, and a gate electrode extending from the gate line52a. Next, a gate insulating layer53is formed over the entire surface of the lower substrate50and on the gate line52a. In one aspect of the present invention, the gate insulating layer53may be formed out of a material such as SiNx, SiOx, and the like, by a deposition method such as Plasma Enhanced Chemical Vapor Deposition (PECVD). In another aspect of the present invention, the gate insulating layer53may be formed of a material such as BenzoCycloButene (BCB), acrylic resin, polyimide compound, and the like, to obtain an LCD device having an increased high aperture ratio.

Next, the gate insulating layer53and the organic insulation layer51may be selectively etched to expose portions of the lower substrate50in regions corresponding to the pixel region and to form an inclined sidewall portion in the organic insulation layer51. In one aspect of the present invention, the inclined sidewall portion may be formed in both the organic insulation layer51and the gate insulating layer53. In one aspect of the present invention, the organic insulation layer51may be formed out of an organic insulating material such as BenzoCycloButene (BCB), photo-acrylic resin, and the like.

Although not shown, first and second semiconductor layers (e.g., amorphous silicon and impurity doped amorphous silicon layers) may be formed over the entire surface of the lower substrate50to form an active layer (not shown). The first and second semiconductor layers may then selectively patterned using a mask to be formed into an island-shaped active layer (not shown) above the gate electrode.

Referring toFIG. 7B, a second metal layer54may be formed over the entire surface of the lower substrate50and on the active layer (not shown).

Referring toFIG. 7C, the second metal layer54may be selectively patterned to form the data line54aarranged along a second direction, substantially perpendicular to the first direction, to define the pixel region, wherein the data line includes data pads (not shown) arranged at opposing ends of the data line54a, and a common auxiliary electrode54bon the inclined sidewall portion of the organic insulation layer51and substantially surrounding the pixel region. In one aspect of the present invention, the second metal layer54may be formed out of a material such as Al, Mo, Cr, Ta, Al alloy, and the like, by a process such as sputtering.

Although not shown, a source electrode may be formed to extend from the data line54atoward the active layer, and a drain electrode (not shown) may be formed to be spaced apart from the source electrode. During patterning of the second metal layer54, the second semiconductor layer may become over-etched between the source and drain electrodes.

After patterning the second metal layer, a passivation layer55may be formed over the entire surface of the lower substrate50, on the data line54a, and on the common auxiliary electrode54b. In one aspect of the present invention, the passivation layer55may be formed out of a material such as BenzoCycloButene (BCB), acrylic resin, polyimide compound, SiNx, or SiOx, and the like. After being formed over the lower substrate50, the passivation layer55may be selectively etched using a photo-mask process to form so that first, second, and third contact holes (not shown) above the drain electrode, the gate pad, and the data pad, respectively.

Next, a transparent conductive metal layer may be formed over the passivation layer55and within the first, second, and third contact holes. Accordingly, a portion of the transparent conductive metal layer provided in the pixel region (i.e., the pixel electrode56) electrically contacts the drain electrode through the first contact hole, a portion of the transparent conductive metal layer provided on the passivation layer and adjacent the second contact hole (i.e., gate pad terminal) may contact the gate pad, and a portion of the transparent conductive metal layer provided on the passivation layer and adjacent the third contact hole (i.e., data pad terminal) may contact the date pad. In one aspect of the present invention, the pixel electrode56may be formed to overlap with at least a portion of the common auxiliary electrode54bformed on the inclined sidewall portion of the organic insulation layer51.

A method for fabricating the upper substrate40will now be described.

Referring toFIG. 7D, a black matrix layer41may be formed over the upper substrate40for preventing light leakage in regions outside the pixel regions of the lower substrate. Next, an RGB color filter layer42, for selectively transmitting light at predetermined wavelengths through respective pixel regions.

Next, a common electrode43may be formed over the entire surface of the upper substrate40and on the color filter layer42. In one aspect of the present invention, the common electrode43may be formed out of transparent conductive material such as ITO.

Subsequently, a photosensitive material may be formed over the common electrode43and selectively patterned by photolithography to form dielectric protrusion44. According to the principles of the present invention, the dielectric protrusion44may distort electric fields applied to the layer of liquid crystal material45. In one aspect of the present invention, the dielectric protrusion44may be formed of a photosensitive material having a dielectric constant substantially equal to or less than the dielectric constant of the liquid crystal material. For example, the dielectric protrusion44may be formed out of a material having the dielectric constant of about 3 or less. Accordingly, the dielectric protrusion44may be formed out of a material such as photoacrylate, BenzoCycloButene (BCB), and the like. In another aspect of the present invention, an electric field inducing window (not shown) may be provided as a hole or slit within the common electrode43as an alternative to forming the dielectric protrusion44.

Next, a spacer (not shown) and sealant material may be formed on one of the lower and upper substrates50and40followed by bonding of the lower and upper substrates50and40. Subsequently, liquid crystal material may be injected between the lower and upper substrates50and40, thereby forming a layer of liquid crystal material45. In one aspect of the present invention, the liquid crystal material may have either a positive or negative dielectric anisotropy. In another aspect of the present invention, a chiral dopant may be added to the liquid crystal material45.

In a third aspect of the present invention, the common auxiliary electrode may be formed above the pixel electrode56, separately from the formation of both the gate and data lines. Accordingly, the common auxiliary electrode according to the third aspect of the present invention may be formed over the inclined sidewall portion of the organic insulation layer51.

According to the principles of the present invention, the common auxiliary electrode may be formed over the inclined sidewall portion of the organic insulation layer such that at least a portion of the common auxiliary electrode is inclined. Accordingly, liquid crystal molecules within the layer of liquid crystal material may be prevented from facing outwardly proximate the perimeter of the pixel region such that the liquid crystal molecules are substantially aligned uniformly. As a result, the time required for the layer of liquid crystal material45to stabilize within the LCD device, and therefore the response time, may be reduced.

According to further principles of the present invention, the common auxiliary electrode, formed on the inclined sidewall portion of the organic insulation layer, reinforces the fringe field. As a result of the reinforcement, liquid crystal molecules may be prevented from facing outwardly at the perimeter of the pixel electrode56such that liquid crystal molecules are uniformly aligned. As a result, the LCD device of the present invention may have an increased aperture ratio.

According to further principles of the present invention, the common auxiliary electrode may be formed simultaneously with the gate line or the data line, thereby simplifying the manufacturing process steps.