KR20070000191A - Ips mode liquid crystal display device and method of manufacturing the same - Google Patents

Abstract

An IPS(In-Plane Switching) mode LCD and a method for manufacturing the same are provided to significantly reduce the widths of a common electrode and a pixel electrode, thereby improving the aperture ratio, by forming the pixel electrode and the common electrode on tapered edges of an insulating pattern. An insulating layer is formed on a substrate(100). A first resist is formed on the insulating layer in a predetermined pattern. The insulating layer is etched using the first resist layer as a mask, thereby forming an insulating pattern(110a) having tapered edges. An electrode layer is formed on the resultant substrate including the insulating pattern. A second resist layer is formed on the electrode layer. The second resist layer is ached such that the second resist layer remains on the tapered edges of the insulating pattern. The electrode layer is pattern-etched using the remaining second resist layer as a mask. The first photoresist layer and the second resist layer are removed, thereby forming a common electrode(200a) and a pixel electrode(200b) on the tapered edges of the insulating pattern. The common electrode and the pixel electrode are parallel with each other.

Description

IPS mode liquid crystal display device and method of manufacturing the same

The present invention relates to a liquid crystal display device, and more particularly to an IPS mode liquid crystal display device.

Ultra-thin flat panel display devices having a thickness of only a few centimeters of the display screen, and liquid crystal display devices (Liquid Crystal Display Device) mainly have a wide range of applications, such as notebook computers, monitors, aircraft.

The liquid crystal display device includes a liquid crystal layer formed between the lower substrate, the upper substrate, and both substrates. The liquid crystal display device is a flat panel display device in which an arrangement of the liquid crystal layers is changed according to voltage application, and accordingly, light transmittance is adjusted to display an image. .

Hereinafter, a conventional liquid crystal display device will be described with reference to the drawings.

1 is a schematic perspective view of a conventional liquid crystal display device, which corresponds to a so-called twisted nematic (TN) mode liquid crystal display device. 1A shows a state where no voltage is applied, and FIG. 1B shows a state where a voltage is applied.

First, the structure of the conventional TN mode liquid crystal display device will be briefly described, and then the driving principle thereof will be described.

The conventional TN mode liquid crystal display device includes a liquid crystal layer 5 between the first substrate 1, the second substrate 3, and both substrates 1, 3.

A first polarizing plate 7 having a transmission axis in a predetermined direction is formed on an outer surface of the first substrate 1, and a second transmission plate having a transmission axis in a direction opposite to the first polarizing plate is formed on an outer surface of the second substrate 3. The polarizing plate 9 is formed.

Although not shown, a pixel electrode is formed on the first substrate 1, and a common electrode is formed on the second substrate 3, so that a vertical electric field is formed between the pixel electrode and the common electrode. .

In the state where no voltage is applied as in FIG. 1A, the liquid crystal layer 5 is arranged in a twisted 90 degree state between the first substrate 1 and the second substrate 3. Herein, when light 10 is incident through the second polarizing plate 9, the light is transmitted through the liquid crystal layer 5. At this time, the liquid crystal molecules are twisted and transmitted 90 degrees in the same manner as the liquid crystal molecules that are twisted by 90 degrees. Will pass through. Thus, the image is in a white state.

In the state where a voltage is applied as shown in FIG. 1B, the liquid crystal molecules forming the liquid crystal layer 5 are vertically arranged between the substrates 1 and 3 by a vertical electric field between the pixel electrode and the common electrode. Herein, when the light 10 is incident through the second polarizing plate 9, the light 10 is transmitted through the liquid crystal layer 5. In this case, rotation of the polarization direction of the light is not performed, and thus the light 10 may not pass through the first polarizing plate 7. Thus, the image is in a black state.

However, such a TN mode liquid crystal display device has a big disadvantage that the viewing angle is narrow.

2 is a diagram illustrating a viewing angle problem of a TN mode liquid crystal display device.

2A is a white display state without a voltage, FIG. 2B is a black display state with a full voltage applied, and FIG. 2C is an intermediate display state with an intermediate voltage applied thereto.

As shown in FIG. 2A, in the state where no voltage is applied, the liquid crystal molecules 5 are twisted at a fine inclination angle in the same direction, and the incident light (shown by the arrow) displays white in any direction.

As shown in FIG. 2B, in the state where the full voltage is applied, the liquid crystal molecules 5 are oriented vertically under the influence of the electric field, and the incident light does not twist and displays black.

As shown in FIG. 2C, the liquid crystal molecules 5 are oriented in an oblique direction in a state where an intermediate voltage is applied, and thus the display state is different according to the direction of incident light. That is, the light incident from the lower right to the upper left does not change the polarization direction of the light, and thus displays black, whereas the light incident from the lower left to the upper right shows the polarized direction of the light at a twisted white.

As described above, the TN mode liquid crystal display device has a disadvantage in that the display state is different according to the incident direction of light and thus the viewing angle is narrow.

Accordingly, researches to broaden the viewing angle have been actively conducted, and various methods have been proposed as part of the research. For example, a so-called IPS (In Plane Switching) mode using a horizontal electric field, an alienated VA (Vertical Alignment) mode using a vertical alignment film, an electrically controlled Birefringence (ECB) mode, etc. have been proposed. A multidomain method using an average value of an array and a phase compensation method of changing a phase difference according to a change in a viewing angle using a phase difference film have been proposed.

The present invention relates to an IPS mode liquid crystal display device among various methods for widening the viewing angle as described above. Hereinafter, the conventional IPS mode liquid crystal display device will be described in more detail.

3 is a view of a conventional IPS mode liquid crystal display device, and FIGS. 3A and 3B are cross-sectional views and a plan view, respectively, without a voltage applied, and FIGS. 3C and 3D are cross-sectional views and a plan view, respectively, with a voltage applied thereto.

First, the structure of the conventional IPS mode liquid crystal display device will be briefly described, and then the driving principle thereof will be described.

The conventional IPS mode liquid crystal display device includes a liquid crystal layer 5 between the first substrate 1, the second substrate 3, and both substrates 1, 3.

A first polarizing plate 7 having a transmission axis in a predetermined direction is formed on an outer surface of the first substrate 1, and a second transmission plate having a transmission axis in a direction opposite to the first polarizing plate is formed on an outer surface of the second substrate 3. The polarizing plate 9 is formed.

Further, the pixel electrode 2 and the common electrode 4 are formed in parallel with each other on the first substrate 1, so that a horizontal electric field is formed between the pixel electrode 2 and the common electrode 4.

In the state where no voltage is applied as shown in FIGS. 3A and 3B, the liquid crystal layer 5 is substantially horizontal with respect to the longitudinal direction of the electrodes 2 and 4 between the first substrate 1 and the second substrate 3. Are arranged. In this case, when the light 10 is incident through the first polarizing plate 7, the light is transmitted through the liquid crystal layer 5, in which the rotation of the polarization direction of the light is not performed so that the transmission axis is opposite to the first polarizing plate 7. It cannot pass through the second polarizing plate 9. Thus, the image is in a black state.

In the state where a voltage is applied as shown in FIGS. 3C and 3D, the liquid crystal layer 5 is arranged differently in the vicinity of the first substrate 1 and in the vicinity of the second substrate 3. That is, in the vicinity of the first substrate 1, the second substrate 3 is arranged in a direction perpendicular to the longitudinal direction of the electrodes 2 and 4 by a horizontal electric field between the pixel electrode 2 and the common electrode 4. ), The electric field is less affected, and is arranged in the horizontal direction with respect to the longitudinal direction of the electrodes 2 and 4 as in the case of no voltage application.

Accordingly, when the light 10 is incident through the first polarizing plate 7, the light is transmitted through the liquid crystal layer 5, and the light is twisted and transmitted like the twisted liquid crystal molecules. Passes through the second polarizing plate (9) opposite. Thus, the image is in a white state.

As described above, since the IPS mode liquid crystal display device switches horizontally without vertically aligning the liquid crystal molecules, the viewing angle characteristic does not change according to the incident direction of light even when an intermediate voltage is applied.

However, the IPS mode liquid crystal display device has a problem in that transmittance is small by forming the pixel electrode 2 and the common electrode 4 on the first substrate 1.

The reason why the transmittance is small is that the aperture ratio decreases by the width of the pixel electrode 2 and the common electrode 4. Currently, the width of the pixel electrode 2 and the common electrode 4 is about 4 μm, which is the minimum thickness that can be formed by the photolithography process. In the case of using the photolithography process, the pixel electrode 2 and the There is a limit in reducing the width of the common electrode 4.

The present invention was devised to solve the above problems, and a first object of the present invention is to provide a method of manufacturing an IPS mode liquid crystal display device which can improve aperture ratio by significantly reducing the width of a pixel electrode and a common electrode by applying a new process. To provide.

A second object of the present invention is to provide an IPS mode liquid crystal display device having an improved aperture ratio by significantly reducing the width of the pixel electrode and the common electrode.

The present invention is a first step of forming an insulating layer on a substrate in order to achieve the first object; A second step of patterning a first resist layer in a predetermined shape on the insulating layer; A third step of forming an insulating layer pattern having tapered edge portions by etching the insulating layer using the patterned first resist layer as a mask; Forming a common electrode and a pixel electrode electrode layer on an exposed substrate surface, a tapered edge portion of the insulating layer, and an upper surface of the first resist layer; A fifth step of forming a second resist layer on the entire surface of the substrate; A sixth step of ashing the second resist layer such that the second resist layer remains only at the tapered edge portion of the insulating layer; A seventh step of etching the electrode layer formed on the exposed substrate surface and the upper surface of the first resist layer; And an eighth process of removing the first resist layer and the remaining second resist layer to form a common electrode and a pixel electrode arranged in parallel with each other at predetermined tapered edge portions of the insulating layer. A method of manufacturing an IPS mode liquid crystal display device is provided.

The present inventors studied a method of greatly reducing the widths of the pixel electrode and the common electrode in order to improve the aperture ratio in the IPS mode liquid crystal display device, and the present invention is characterized in that the edge portion of the insulating layer is tapered during the etching process. In view of the above, when the pixel electrode and the common electrode are formed on the tapered edge portion of the insulating layer, it was confirmed that the width of the pixel electrode and the common electrode can be greatly reduced, thereby completing the present invention.

Here, the third process may be performed by a wet etching process using an etchant, or may be performed through a dry etching process using an etching gas. However, when performing the dry etching process, it is preferable to inject the etching gas inclinedly.

In addition, the sixth step is preferably performed using an oxygen plasma.

In addition, the seventh process may be performed through a dry etching process using an etching gas. However, it is preferable to vertically administer the etching gas during the dry etching process.

In addition, the present invention, in order to achieve the second object, the first substrate and the second substrate facing each other and provided with a pixel region; A liquid crystal layer formed between the substrates; An insulating layer having an edge portion tapered in the pixel area on the first substrate; The present invention provides an IPS mode liquid crystal display device including a pixel electrode and a common electrode having a predetermined inclination at a tapered edge portion of the insulating layer and arranged in parallel with each other.

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

1. Manufacturing method of IPS mode liquid crystal display device

4A through 4H are cross-sectional views illustrating a manufacturing process of an IPS mode liquid crystal display device according to an exemplary embodiment of the present invention, in which only a pixel electrode and a common electrode are formed in a unit pixel region of the IPS mode liquid crystal display device. It is shown. Other portions may be modified in various ways known in the art.

First, as shown in FIG. 4A, the insulating layer 110 is formed on the substrate 100.

The insulating layer 110 may be made of an inorganic insulating material such as SiOx, SiNx, or may be made of an organic insulating material such as benzocyclobutene (BCB) or polyvinyl alcohol (Polyvinylalcohol), and a double layer of an inorganic insulating material and an organic insulating material. It may be made of.

The insulating layer 110 may function as a gate insulating film and / or a protective film of the liquid crystal display device.

Thereafter, as shown in FIG. 4B, the first resist layer 120 is formed in a predetermined shape on the insulating layer 110.

The first resist layer 120 may be formed by patterning a photoresist material capable of reacting with light through an exposure process.

Thereafter, as illustrated in FIG. 4C, the insulating layer is etched using the patterned first resist layer 120 as a mask to form an insulating layer pattern 110a having tapered edges.

The insulating layer pattern 110a having the tapered edge portion may be formed by a wet etching process or a dry etching process.

In the wet etching process, the etching liquid penetrates into the lower part of the mask due to the process characteristics. Thus, when the wet etching process is used, the insulating layer 110a may be etched to penetrate the lower portion of the first resist layer 120 to taper the edge portion thereof. Can be.

In the case of using the dry etching process, the insulating layer 100a may be etched such that the edge portion is tapered by inclining the etching gas.

After that, as shown in FIG. 4D, the common electrode and the pixel electrode electrode layer 200 are disposed on the exposed surface of the substrate 100, the tapered edge portion of the insulating layer 110a, and the upper surface of the first resist layer 120. Form.

The material of the electrode layer 200 may be a transparent metal such as ITO or an opaque metal such as Mo or Ti.

Forming the electrode layer 200 on the exposed surface of the substrate 100 and the upper surface of the first resist layer 120 is possible through a deposition process or a sputtering process under a conventional condition, and the taper of the insulating layer 110a It is possible to form the electrode layer 200 at the deep edge portion by adding a slight modification to the normal process conditions.

For example, when the pressure is set higher than normal conditions in the deposition process, the path of the electrode layer material to be increased may be changed to be inclined by the pressure, so that the electrode layer 200 may be formed at the tapered edge portion.

Thereafter, as shown in FIG. 4E, the second resist layer 130 is formed on the entire surface of the substrate.

The second resist layer 130 may be formed of the same material as the first resist layer 120 or may be formed of a different material.

Thereafter, as illustrated in FIG. 4F, the second resist layer 130 is ashed to leave the second resist layer 130a only at the tapered edge portion of the insulating layer 110a.

The ash treatment may be performed using an oxygen plasma.

Thereafter, as illustrated in FIG. 4G, the electrode layer 200 formed on the exposed substrate surface 100 and the first resist layer 120 is etched. Then, the electrode layers 200a and 200b remain only at the tapered edge portions of the insulating layer 110a.

Such a process may be performed through a dry etching process in which the etching gas is vertically administered. When the etching gas is vertically administered, the electrode layer 200 formed on the exposed surface of the substrate 100 and the upper surface of the resist layer 120 is etched, whereas the electrode layer 200a formed on the tapered edge portion of the insulating layer 110a, The second resist layer 120a and the remaining second resist layer 130a serve as a mask and remain without being etched.

Thereafter, as shown in FIG. 4H, the common resist 200a and the pixel electrode 200b are completed by removing the first resist layer 120 and the remaining second resist layer 130a.

The common electrode 200a and the pixel electrode 200b have a predetermined slope in the tapered edge portion of the insulating layer 110a in cross section and are arranged parallel to each other in a plane, thereby forming a horizontal electric field therebetween. Will be.

As described above, the width (length X in FIG. 4H) of the common electrode 200a and the pixel electrode 200b may be formed to be 1 μm or less by the same process as in FIGS. 4A to 4H, thereby greatly increasing the aperture ratio.

Meanwhile, as described above, only the pixel electrode and the common electrode are formed in the unit pixel region in FIGS. 4A to 4H, and the gate line and the data line intersecting each other in the unit pixel region, The thin film transistor is formed at the intersection of the data lines.

Specific methods of forming the gate line, the data line, and the thin film transistor may be performed by various methods known in the art.

4A to 4H illustrate only a process of forming a substrate on which a pixel electrode and a common electrode are formed. In the IPS liquid crystal display device, the substrate and the opposing substrate facing the substrate are bonded to each other with a liquid crystal layer interposed therebetween. do.

In this case, the counter substrate is manufactured by sequentially forming a light shielding layer for weaving light leakage, and a color filter layer of red, blue, and green.

In addition, a spacer may be further formed on one of the above substrates to maintain a cell gap of the liquid crystal display device.

In addition, an alignment layer may be further formed on at least one of the above substrates for the initial alignment of liquid crystals. The alignment layer may be formed by rubbing alignment treatment using a polyamide or polyimide compound, PVA (polyvinylalcohol), polyamic acid, or the like, or PVCN (polyvinylcinnamate) or PSCN (polyvinylcinnamate). It may be formed by photo-alignment treatment using a photoreactive material such as polysiloxanecinnamate) or CelCN (cellulosecinnamate) compound.

On the other hand, there are a vacuum injection method and a liquid crystal dropping method as a method of forming a liquid crystal layer between both substrates.

The vacuum injection method is a method of injecting the liquid crystal through a predetermined injection hole after the two substrates are bonded, the liquid crystal dropping method is a method of bonding both substrates after dropping the liquid crystal on any one of the two substrates. Since the vacuum injection method takes a long time to inject the liquid crystal when the size of the substrate is large, the productivity is decreased, so the liquid crystal dropping method is preferable.

2. IPS mode liquid crystal display device

FIG. 5 is a cross-sectional view of an IPS mode liquid crystal display device according to an exemplary embodiment of the present invention, which illustrates only a state in which a pixel electrode and a common electrode are formed in a unit pixel area of an IPS mode liquid crystal display device.

As can be seen in Figure 5, the IPS mode liquid crystal display device according to the present invention is a liquid crystal layer 400 formed between the first substrate 100 and the second substrate 300 and the two substrates (100, 300) facing each other )

The first substrate 100 has an insulating layer 110a having a tapered edge portion.

The common electrode 200a and the pixel electrode 200b are arranged in parallel with each other at predetermined tapered edges of the insulating layer 110a.

The material of the common electrode 200a and the pixel electrode 200b may be a transparent metal such as ITO or an opaque metal such as Mo or Ti.

The width X of the common electrode 200a and the pixel electrode 200b is 1 μm or less.

Although not shown, a gate line and a data line are formed on the first substrate 100 to cross each other to define a pixel region, and a thin film transistor is formed at an intersection of the gate line and the data line.

In addition, the substrates 100 and 300 are sealed by a sealing material, and spacers are formed between the substrates 100 and 300 so as to maintain a cell gap of the liquid crystal display device. The spacer may be a ball-shaped ball spacer or a columnar column spacer.

In addition, an alignment layer for initial alignment of liquid crystals is formed on at least one of the substrates 100 and 300.

In addition, although not specifically described, various components other than the common electrode 200a and the pixel electrode 200b which are the core of the present invention may be changed by various methods known to those skilled in the art.

According to the present invention having the above-described configuration, the common electrode and the pixel electrode can be formed to 1 μm or less, and the aperture ratio is greatly improved as compared with the prior art, thereby improving the transmittance.

1A and 1B are diagrams schematically illustrating a state in which no voltage is applied and a state in which a voltage is applied in a conventional twisted nematic (TN) mode liquid crystal display device, respectively.

FIG. 2 illustrates a problem in that a narrow viewing angle is formed in a conventional TN mode liquid crystal display device. FIG. 2A illustrates a white display state without a voltage, FIG. 2B shows a black display state with a full voltage applied, and FIG. 2C shows an intermediate voltage. It is a figure which shows the intermediate display state which applied.

3 is a view of a conventional IPS mode liquid crystal display device, and FIGS. 3A and 3B are cross-sectional views and a plan view, respectively, without a voltage applied, and FIGS. 3C and 3D are cross-sectional views and a plan view, respectively, with a voltage applied thereto.

4A to 4H are cross-sectional views illustrating a manufacturing process of an IPS mode liquid crystal display device according to an exemplary embodiment of the present invention.

5 is a cross-sectional view of an IPS mode liquid crystal display device according to an exemplary embodiment of the present invention.

<Description of Signs of Major Parts of Drawing>

100: substrate 110, 110a: insulating layer

120: first resist layer 130: second resist layer

200: metal layer 200a, 200b: common electrode, pixel electrode

Claims (14)

A first step of forming an insulating layer on the substrate; A second step of patterning a first resist layer in a predetermined shape on the insulating layer; A third step of forming an insulating layer pattern having tapered edge portions by etching the insulating layer using the patterned first resist layer as a mask; Forming a common electrode and a pixel electrode electrode layer on an exposed substrate surface, a tapered edge portion of the insulating layer, and an upper surface of the first resist layer; A fifth step of forming a second resist layer on the entire surface of the substrate; A sixth step of ashing the second resist layer such that the second resist layer remains only at the tapered edge portion of the insulating layer; A seventh step of etching the electrode layer formed on the exposed substrate surface and the upper surface of the first resist layer; And And an eighth process of removing the first resist layer and the remaining second resist layer to form a common electrode and a pixel electrode arranged in parallel with each other at predetermined tapered edge portions of the insulating layer. Method of manufacturing a mode liquid crystal display device. The method of claim 1, And the third process is performed by a wet etching process using an etchant. The method of claim 1, Wherein the third process is performed through a dry etching process using an etching gas, the manufacturing method of the IPS mode liquid crystal display device, characterized in that performed by inclining the etching gas. The method of claim 1, The sixth step is a method of manufacturing an IPS mode liquid crystal display device, characterized in that performed using oxygen plasma. The method of claim 1, The seventh process is performed through a dry etching process using an etching gas, the manufacturing method of the IPS mode liquid crystal display device, characterized in that performed by vertically administering the etching gas. The method of claim 1, Forming a gate line and a data line on the substrate to cross each other; And And forming a thin film transistor in an intersection region of the gate line and the data line. The method of claim 6, Preparing an opposing substrate facing the substrate and having a light shielding layer and a color filter layer thereon; And A method of manufacturing an IPS mode liquid crystal display device, further comprising the step of forming a liquid crystal layer between the both substrates. The method of claim 7, wherein Forming a liquid crystal layer between the both substrates Dropping a liquid crystal layer onto any one of the above substrates; And A method of manufacturing an IPS mode liquid crystal display device, characterized in that the step of bonding both the substrates. A first substrate and a second substrate facing each other and provided with pixel regions; A liquid crystal layer formed between the substrates; An insulating layer having an edge portion tapered in the pixel area on the first substrate; An IPS mode liquid crystal display device comprising a common electrode and a pixel electrode having a predetermined slope on the tapered edge portion of the insulating layer and arranged in parallel with each other. The method of claim 9, And the common electrode and the pixel electrode are made of a transparent metal or an opaque metal. The method of claim 9, Wherein the common electrode and the pixel electrode have a width of 1 μm or less. The method of claim 9, A gate line and a data line formed on the first substrate to cross each other; And And a thin film transistor formed at an intersection of the gate line and the data line. The method of claim 9, And a light blocking layer and a color filter layer formed on the second substrate. The method of claim 9, And a spacer for maintaining a cell gap between the first substrate and the second substrate.