KR100670061B1 - Vertically Aligned Liquid Crystal Display - Google Patents

Abstract

The gate wiring and the common electrode wiring are formed on the lower substrate, and the insulating film is formed on the gate wiring and the common electrode wiring. A pixel electrode made of a transparent insulating material such as indium tin oxide (ITO) or indium zinc oxide (IZO) is formed on the insulating film. Openings are formed in the pixel electrode, and insulating protrusions are formed on the pixel electrode. At this time, the insulating protrusions cover a part of the openings of the pixel electrode, and the openings covered by the protrusions and the openings which are not are alternately arranged. The common electrode wirings are arranged under the openings not covered by the projections and overlap the openings. In this case, the fringe field may be strengthened by distorting the electric field, thereby improving the response speed of the liquid crystal display and stabilizing the domain.

LCD, vertical alignment, fringe field, opening pattern, projection

Description

Vertically oriented liquid crystal display {A VERTICALLY ALIGNED MODE LIQUID CRYSTAL DISPLAY}

1 is a cross-sectional view of a liquid crystal display device according to a first embodiment of the present invention;

2 is a front view of a thin film transistor substrate for a liquid crystal display according to a second embodiment of the present invention;

3 is a front view of a thin film transistor substrate for a liquid crystal display according to a third embodiment of the present invention;

4 is a cross-sectional view of a thin film transistor substrate for a liquid crystal display according to a fourth embodiment of the present invention;

5 is a front view of a thin film transistor substrate for a liquid crystal display according to a fifth embodiment of the present invention;

6 is a simulation result of a liquid crystal display according to a fourth exemplary embodiment of the present invention.

7 is a cross-sectional view of a liquid crystal display according to a sixth exemplary embodiment of the present invention.

8 is a simulation result of a liquid crystal display according to a sixth exemplary embodiment of the present invention.

9 is a cross-sectional view of a thin film transistor substrate for a liquid crystal display according to a seventh embodiment of the present invention;

10 is a simulation result of a liquid crystal display according to a seventh exemplary embodiment of the present invention.

11 is a cross-sectional view of a thin film transistor substrate for a liquid crystal display according to an eighth embodiment of the present invention;

12 is a cross-sectional view of a thin film transistor substrate for a liquid crystal display according to a ninth embodiment of the present invention;

13 is a cross-sectional view of a thin film transistor substrate for a liquid crystal display according to a tenth embodiment of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to a vertical alignment mode liquid crystal display device having an opening pattern formed on an electrode to secure a wide viewing angle.

In general, a liquid crystal display device injects a liquid crystal material between an upper substrate on which a common electrode, a color filter, and the like are formed, and a lower substrate on which a thin film transistor and a pixel electrode are formed. By applying a different potential to form an electric field to change the arrangement of the liquid crystal molecules, and through this to control the light transmittance is a device that represents the image.

Among them, the vertical alignment mode liquid crystal display in which the long axis of the liquid crystal molecules are arranged perpendicular to the upper and lower substrates without an electric field is applied, and thus, the contrast ratio is large and the wide viewing angle is easily realized.

There is a method of forming an opening pattern in an electrode as a means for implementing a wide viewing angle in a vertical alignment mode liquid crystal display. This method is a method of securing a wide viewing angle by evenly dispersing the tilting direction of the liquid crystal in four directions using a fringe field.

In the conventional method of forming the opening pattern, an opening pattern is formed on the pixel electrode and the common electrode, and the viewing angle is widened by adjusting the direction in which the liquid crystal molecules lie down using a fringe field formed by the opening patterns. There is this.

However, in this case, since the common electrode made of indium tin oxide (ITO) formed on the color filter is patterned by using photolithography, a photolithography process is added.

In addition, the adhesion between the ITO deposited on the color filter by sputtering and the color filter resin is not good, so that the precision of the common electrode is inferior. In addition, there is a problem that damage occurs when the color filter is exposed during ITO etching, in order to prevent this, a reliable organic insulating film (overcoat film) must be coated on the color filter. However, there is a problem that the overcoat film is expensive. When the overcoat layer is formed, the common electrode may not directly contact a black matrix formed of chromium (Cr), and so the resistance may increase, resulting in a serious flicker defect.

In addition, since an opening pattern is formed in the common electrode, an increase in resistance of the common electrode is increased.

On the other hand, when the upper and lower substrates are aligned, the opening pattern formed on the common electrode of the upper plate and the opening pattern formed on the pixel electrode of the lower plate also have difficulty in accurately aligning.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a method of forming opening patterns and protrusions for widening a viewing angle without complicating a manufacturing process of a liquid crystal display device.

In order to solve this problem, in the present invention, first and second openings are formed in the pixel electrode, and protrusions are formed to overlap the first opening.

Specifically, the gate wiring formed on the insulating substrate, the gate insulating film formed on the gate wiring, the semiconductor pattern formed on the gate insulating film, the data insulating film formed on the gate insulating film and the semiconductor pattern, and the protective film formed on the data wiring. And a pixel electrode formed on the insulating substrate, the pixel electrode having a first opening and a second opening, and having a projection made of a gate insulating film and a protective film covering the first opening.

Alternatively, the gate wiring formed on the insulating substrate, the gate insulating film formed on the gate wiring, the semiconductor pattern formed on the gate insulating film, the data wiring formed on the gate insulating film and the semiconductor pattern, the protective film formed on the data wiring and the insulation A substrate for a liquid crystal display device including a pixel electrode formed on a substrate and having a first opening and a second opening, and having a protrusion formed of a gate insulating film, a semiconductor pattern layer, and a protective film covering the first opening.

Next, a structure of a thin film transistor substrate for a liquid crystal display according to an exemplary embodiment of the present invention will be described with reference to the drawings.

1 is a cross-sectional view of a liquid crystal display according to a first exemplary embodiment of the present invention.

A gate wiring (not shown) and a common electrode wiring 110 are formed on the lower substrate 100 made of an insulating material such as glass, and an insulating film 120 is formed on the gate wiring and the common electrode wiring 110. . The pixel electrode 130 made of a transparent insulating material such as indium tin oxide (ITO) or indium zinc oxide (IZO) is formed on the insulating layer 120. Openings 131 and 132 are formed in the pixel electrode 130, and an insulating protrusion 140 is formed on the pixel electrode 130. In this case, the insulating protrusion 140 covers a portion 131 of the openings 131 and 132 of the pixel electrode 130, and the opening 131 covered by the protrusion 140 and the opening 132 which are not covered by the protrusion 140 alternately. It is arranged. The common electrode wiring 110 is disposed below the opening 132 not covered by the protrusion 140 to overlap the opening 132.

The upper substrate 200 has a common electrode 210 made of a transparent conductive material such as ITO or IZO.

은 0.75에서 0.1,

는 -4에서 -6로 액정은 음의 유전율 이방성을 가진다.A liquid crystal material having negative dielectric anisotropy is injected between the lower substrate 100 and the upper substrate 200 to form the liquid crystal layer 300. Where liquid crystal

Is 0.75 to 0.1,

Is -4 to -6, the liquid crystal has negative dielectric anisotropy.

As described above, when the openings 131 and 132 are formed in the pixel electrode 130, and the protrusions 140 are formed in a part thereof, as shown in FIG. 1, the protrusions 140 and the openings 132 are centered. The domains are divided and a stable liquid crystal array is formed. At this time, forming the opening 131 under the protrusion 140 is essential to stabilize the texture (texture). This creates a stable texture on the protrusions. In addition, as shown in FIG. 1, when the common electrode wiring 110 is disposed below the opening 132 where the protrusion 140 of the pixel electrode 130 is not formed, the fringe field is strengthened to further increase the domain. It stabilizes and the response speed increases.

에서 5

사이, 높이는 1㎛에서 3㎛ 사이가 적합한 것으로 나타났다. 또한 돌기의 폭은 15㎛ 내지 25㎛가 바람직하다.An important factor in the above liquid crystal display device is the dielectric constant and height of the projections. Simulation results show that the dielectric constant is 1

In 5

In the meantime, it was found that the height was suitably between 1 µm and 3 µm. Moreover, as for the width of a processus | protrusion, 15 micrometers-25 micrometers are preferable.

In the liquid crystal display having the above structure, since the common electrode 210 of the upper plate 200 is not patterned, all problems caused by patterning the common electrode 210 are solved. In addition, since the direction of the electric field forms a large angle with the long axis direction of the liquid crystal, it is expected to improve the response speed compared to the conventional.

2 is a front view of a thin film transistor substrate for a liquid crystal display according to a second embodiment of the present invention, and FIG. 3 is a front view of a thin film transistor substrate for a liquid crystal display according to a third embodiment of the present invention.

2 and 3 are views illustrating the arrangement of the openings 131 and 132 and the protrusions 140 in one pixel, and the liquid crystal display having the cross-sectional structure according to the first embodiment of the present invention.

Referring to FIG. 2, openings 131 and 132 in a vertical direction are formed in an upper surface of the rectangular pixel electrode 130, and openings 131 and 132 in a horizontal direction are formed in a lower surface thereof. The protrusions 140 are covered by some of the openings 131, and the common electrode wiring 110 passes through the remaining openings 132. The openings 131 covered by the protrusions 140 and the openings 132 which are not, are alternately arranged.

Referring to FIG. 3, openings 131 and 132 are formed in oblique directions on the upper and lower surfaces of the rectangular pixel electrode 130, respectively. At this time, the openings 131 and 132 of the upper surface and the openings 131 and 132 of the lower surface are perpendicular to each other. As in FIG. 2, the openings 131 are covered by the protrusions 140, and the common electrode wiring 110 passes through the remaining openings 132, and the openings 131 which are not covered by the protrusions 140 are not. The openings 132 are alternately arranged.

4 is a cross-sectional view of a thin film transistor substrate for a liquid crystal display according to a fourth embodiment of the present invention.

The gate wiring 113 and the metal piece 114 formed of a double layer of the aluminum layer 111 and the chromium layer 112 are formed on the insulating substrate 100. The metal piece 114 is formed in the side by side strip | belt shape separated by both sides. A gate insulating film 121 is formed on the gate wiring 113 and the metal piece 114, and an amorphous silicon layer 150 serving as a channel portion of the thin film transistor is formed on the gate insulating film 121, and an amorphous silicon layer ( The n + amorphous silicon layer 160, which is an ohmic contact layer, is formed on the 150. A data line 170 including a source electrode and a drain electrode is formed on the n + amorphous silicon layer 160, and a passivation layer 122 is formed on the data line 170. At this time, the gate insulating film 121 and the protective film 122 are removed except for the two pieces of metal 114 separated from the thin film transistor portion to expose the substrate. As a result, the gate insulating film 121 and the protective film 122 formed between the metal pieces 114 protrude relative to the surroundings to function as protrusions. The pixel electrode 130 made of a transparent conductive material such as ITO is formed on the exposed substrate 100. The pixel electrode 130 is connected to the drain electrode of the thin film transistor and has an opening. A portion of the opening of the pixel electrode 130 exposes a protrusion formed of the gate insulating layer 121 and the passivation layer 122 between the metal piece 114, and the periphery of the opening of the pixel electrode 130 may be formed of the metal piece 114. Some overlapping contacts.

The planar arrangement of the liquid crystal display substrate may be clearly understood through FIG. 5.

5 is a front view of a thin film transistor substrate for a liquid crystal display according to a fifth embodiment of the present invention, and is an example of a planar arrangement of the substrate for a liquid crystal display according to the fourth embodiment.                     

Openings 131 and 132 are formed in diagonal directions on the top and bottom surfaces of the rectangular pixel electrode 130, respectively. At this time, the openings 131 and 132 of the upper surface and the openings 131 and 132 of the lower surface are perpendicular to each other. As in FIG. 2, some of the openings 131 are covered by the protrusions 140, and the openings 131 and the openings 132 which are not covered by the protrusions 140 are alternately disposed. On both sides of the opening 131 covered by the protrusion 140, strip-shaped metal pieces 110 are arranged side by side.

When the substrate for a liquid crystal display device is formed in the above structure, as shown in FIG. 6, a stable domain can be formed centering on the projection and the opening, and the response speed can be improved. In addition, it does not require an additional process for forming protrusions, which is advantageous for process simplification.

Next, a process of manufacturing the liquid crystal display substrate according to the fourth embodiment will be described.

First, a double layer of aluminum and chromium is sequentially deposited on the substrate 100 and photo-etched to form the gate wiring 113 and the metal piece 114.

Next, the gate insulating layer 121, the amorphous silicon layer 150, and the n + amorphous silicon layer 160 are successively deposited and photo-etched to form the semiconductor patterns 150 and 160.

A metal such as chromium is deposited on the n + amorphous silicon layer 160 and photo-etched to form a data line including a source electrode and a drain electrode, and then the exposed n + amorphous silicon layer 160 between the source electrode and the drain electrode is formed. Etch and remove

Next, the protective layer 122 is deposited on the data line and photo-etched to form a contact hole for exposing the drain electrode, and the protective layer 122 and the gate insulating layer 121 of the pixel region are patterned to form protrusions.

Finally, the transparent conductive material is deposited and photo-etched to form the pixel electrode 130 having an opening.

As described above, by forming the projections together in the step of forming the contact hole, the addition of the step for forming the projections is prevented.

7 is a cross-sectional view of a liquid crystal display according to a sixth embodiment of the present invention, and FIG. 8 is a simulation result of the liquid crystal display according to the sixth embodiment of the present invention.

Referring to FIG. 7, an insulating protrusion 140 is formed on the lower substrate 100, and the pixel electrode 130 covers the insulating protrusion 140. Here, the openings 131 and 132 are formed in the pixel electrode 130, and some of the openings 131 are positioned above the protrusions 140 to expose a portion of the protrusions 140, and the remaining portions 132 are exposed. Is located in the region between the protrusion 140 and the protrusion. At this time, a common electrode wiring 110 is formed in the latter opening 132.

The common electrode 210 is formed on the upper substrate 200.

A liquid crystal material is injected between the upper substrate 200 and the lower substrate 100 to form the liquid crystal layer 300.

Positioning the opening 131 on the protrusion 140 in the above structure is essential to stabilize the texture. In such a structure, an equipotential curve is formed in a step shape to tilt the liquid crystal director in one direction in the region between the opening and the protrusion. In addition, as shown in the figure, when the common electrode 110 is disposed in the opening 132, the fringe field is strengthened to stabilize the domain and improve the response speed. Important factors in this structure include the width of the openings 131 and 132 of the pixel electrode 130 and the pretilt angle of the liquid crystals on the projection inclined planes. As a result of the simulation, the width of the openings 131 and 132 is 4 μm. Between 10 μm, the pretilt angle was found to be suitable between 70 ° and 90 °.

9 is a cross-sectional view of a thin film transistor substrate for a liquid crystal display according to a seventh embodiment of the present invention, and FIG. 10 is a simulation result of the liquid crystal display according to the seventh embodiment of the present invention.

A gate wiring 113 formed of a double layer of an aluminum layer 111 and a chromium layer 112 is formed on the insulating substrate 100. A gate insulating layer 121 is formed on the gate wiring 113, an amorphous silicon layer 150 serving as a channel portion of the thin film transistor is formed on the gate insulating layer 121, and an ohmic contact layer is formed on the amorphous silicon layer 150. Phosphorus n + amorphous silicon layer 160 is formed. A data line 170 including a source electrode and a drain electrode is formed on the n + amorphous silicon layer 160, and a metal piece 171 is formed on the gate insulating layer 121 in the pixel region. At this time, the metal piece 171 is formed in the side by side strip shape separated by both sides. The passivation layer 122 is formed on the data line 170. At this time, the gate insulating layer 121 and the passivation layer 122 are removed except for the two pieces of metal 171 separated from the thin film transistor portion to expose the substrate 100. As a result, the gate insulating film 121 and the protective film 122 formed between the metal pieces 171 protrude relative to the surroundings to function as protrusions. In addition, the metal piece 171 is positioned between the gate insulating film 121 and the passivation layer 122, and the outline of the gate insulating layer 121 coincides with the left and right outer outlines of the metal piece 171, but the outline of the passivation layer 122 is Partly overlaps with both metal pieces 171 and contacts. The pixel electrode 130 made of a transparent conductive material such as ITO is formed on the exposed substrate 100. The pixel electrode 130 is connected to the drain electrode of the thin film transistor and has an opening. Some of the openings of the pixel electrode 130 expose the projections formed of the passivation layer 122 between the metal pieces 171, and the periphery of the opening of the pixel electrode 130 overlaps with portions of both metal pieces 171, respectively. Doing.

As such, when the metal pieces under the protrusions are not formed as the gate wiring 113 layer but the data wires 170 layer, an empty space may be prevented from being formed under the protrusions during the pixel electrode 130 formation process. By forming in two stages, the effect due to the step between the protrusion and the pixel electrode can be simultaneously obtained, and the texture can be further stabilized. Looking at Figure 10, this effect can be seen.

However, in such a structure, a texture may occur in the upper part of the protrusion and may invade the domain. The reason for this is that the vertical electric field with respect to the substrate in the upper part of the protrusion is too large. When the liquid crystal molecules lie down by the vertical electric field, the texture splats and invades the domain.

One way to prevent this is to make the dielectric constant of the projections smaller than that of the liquid crystal. This weakens the strength of the electric field above the projections and enhances the alignment control force, which prevents the liquid crystals from lying down. In the simulation, when the dielectric constant of the insulating film was 3, a very stable domain was obtained. Among the inorganic insulating films, SiOx is suitable for use for the above applications with a dielectric constant of about 3.4. When the width of the common electrode was set to 6 mu m and the protrusions were formed on the electrode at 1 mu m using an insulating film having a dielectric constant of 3.0, a stable state was obtained up to 430 kPa.

In another method, the opening width of the pixel electrode positioned on the protrusion is wider than 10 μm and a groove is formed in the center of the protrusion to have a pretilt angle on the liquid crystal molecules. This method is illustrated in FIGS. 11 and 12.

11 is a cross-sectional view of a thin film transistor substrate for a liquid crystal display according to an eighth embodiment of the present invention, and FIG. 12 is a cross-sectional view of a thin film transistor substrate for a liquid crystal display according to a ninth embodiment of the present invention.

In FIG. 11, grooves are formed in the protective film 122 layer of the same structure or protrusion as in FIG. 9. This is possible by forming the protective film 122 so as to extend over the two metal pieces 171.

FIG. 12 increases the depth of the groove by leaving the semiconductor layers 150 and 160 under the metal piece 171 as the data wiring layer.

Next, a method of manufacturing the liquid crystal display substrates according to the seventh and eighth embodiments of the present invention will be described.

First, a double layer of aluminum and chromium is sequentially deposited on the substrate 100 and photo-etched to form the gate wiring 113 and the metal piece 114.                     

Next, the gate insulating layer 121, the amorphous silicon layer 150, and the n + amorphous silicon layer 160 are successively deposited and photo-etched to form the semiconductor patterns 150 and 160.

A metal such as chromium is deposited on the n + amorphous silicon layer 160 and photo-etched to form the data wiring 170 and the metal piece 171 including the source electrode and the drain electrode, and then exposed between the source electrode and the drain electrode. The n + amorphous silicon layer 160 is etched and removed.

Next, the protective layer 122 is deposited on the data line and photo-etched to form a contact hole for exposing the drain electrode, and the projection layer is formed by patterning the protective layer 122 and the gate insulating layer 121 in the pixel region. At this time, the photoresist pattern for forming the projections should be adjusted to the width of the photoresist pattern so that the outer portion of the both sides of the metal piece 171 can be exposed. In this case, when the protective film 122 and the gate insulating film 121 are etched using the photoresist pattern as an etching mask, the metal piece 171 also acts as an etching mask so that the width of the gate insulating film 121 is the width of the protective film 122. It is wider than that.

Finally, the transparent conductive material is deposited and photo-etched to form the pixel electrode 130 having an opening.

The liquid crystal display substrate according to the ninth embodiment of the present invention is a semiconductor in the protrusion part in the step of forming the semiconductor pattern (150, 160) in the method for manufacturing the liquid crystal display substrate according to the seventh and eighth embodiment It can be prepared by leaving a layer.

13 is a cross-sectional view of a thin film transistor substrate for a liquid crystal display according to a tenth embodiment of the present invention.                     

The tenth embodiment is the same as the sixth embodiment of FIG. 7 except that the common electrode wiring 115 is formed under the protrusion.

As described above, the fringe field may be strengthened by distorting the electric field by forming protrusions to overlap some openings, thereby improving the response speed of the liquid crystal display and stabilizing the domain.

Claims (26)

Insulation board, A pixel electrode formed on the insulating substrate and having first and second openings; An insulating protrusion formed on the pixel electrode and covering the first opening; A substrate for a liquid crystal display device comprising a. In claim 1, The substrate for the liquid crystal display device of which the first opening portion and the second opening portion are alternately disposed. The method of claim 1 or 2, And a common electrode wiring having a portion overlapping with the second opening. In claim 1, A part of the first and second openings is formed in the first direction, and the other part is formed in the second direction. In claim 1, The height of the projection is 1㎛ 3㎛ substrate for liquid crystal display device. In claim 1, The dielectric constant of the material forming the protrusions is 1

In 5

Substrate for liquid crystal display device. In claim 1, And the pixel electrode has a metal film pattern formed around the first opening, and the protrusion overlaps with the metal film pattern. In claim 7, And the metal layer pattern is formed of the same material on the same layer as the gate line, and the protrusion is formed of a gate insulating layer and a protective layer. Insulation board, A gate wiring formed on the insulating substrate, A gate insulating film formed on the gate wiring, A semiconductor pattern formed on the gate insulating film, A data line formed on the gate insulating film and the semiconductor pattern; A protective film formed on the data wiring, and A pixel electrode formed on the insulating substrate and having a first opening and a second opening; A projection formed of the gate insulating film and the protective film covers the first opening. In claim 9, And a first metal layer pattern formed on the insulating substrate and made of the same material as the gate wiring and overlapping the protrusion. In claim 10, The first metal film pattern is a substrate for a liquid crystal display device formed of a double layer of aluminum and chromium. The method of claim 9 or 10, And a second metal layer pattern formed on the gate insulating layer and made of the same material as the data line and overlapping the protrusion. In claim 12, And the pixel electrode is in contact with the second metal film pattern. In claim 13, The protective film layer of the protrusion is partially overlapped with the second metal film pattern and separated from the pixel electrode. In claim 9, And the first opening and the second opening are alternately disposed. The method of claim 15, And a common electrode wiring having a portion overlapping with the second opening. Insulation board, An insulating protrusion formed on the insulating substrate, A pixel electrode formed on the insulating protrusion and having the first opening and the second opening; Including, And the first opening exposes a portion of the insulating protrusion. The method of claim 17, And a common electrode wiring having a portion overlapping with the second opening. The method of claim 17, And a common electrode wiring having a portion overlapping with the first opening. The method of claim 17, The first and second openings have a width of 4 μm to 10 μm. The method of claim 17, The projection is a substrate for a liquid crystal display device consisting of a gate insulating film and a protective film. Insulation board, A gate wiring formed on the insulating substrate, A gate insulating film formed on the gate wiring, A semiconductor pattern formed on the gate insulating film, A data line formed on the gate insulating film and the semiconductor pattern; A protective film formed on the data wiring, and A pixel electrode formed on the insulating substrate and having a first opening and a second opening; A projection comprising the gate insulating film, the semiconductor pattern layer, and the protective film covers the first opening. The method of claim 22, And a second metal layer pattern formed on the semiconductor pattern layer and made of the same material as the data line and overlapping the protrusion. The method of claim 23, And the pixel electrode is in contact with the second metal film pattern. The method of claim 24, The protective film layer of the protrusion is partially overlapped with the second metal film pattern and separated from the pixel electrode. The method of claim 24, The semiconductor pattern layer and the second metal film pattern of the protrusion are separated on both sides, and the protective film layer is formed over the separated both sides of the second metal film pattern, the center is recessed substrate.

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