JP2003098539A - Liquid crystal display device and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the performance of brightness and contrast by eliminating a light-passing problem in both of the voltage-applied and unapplied states. SOLUTION: An insulating film pattern 20 formed thinner than that of each signal wiring 12 is formed between the signal wirings 12, and an interlayer insulating film 14 arranged on the signal wiring 12 each and the insulating film pattern 20 is formed high so that a projecting area 14a corresponding to the top of each signal wiring 12 is able to reduce a width of a light-passing area occurring at the time of applying voltage to a pixel electrode 15 in the liquid crystal layer, and moreover, a slant area 14c corresponding to over the gap between each signal wiring 12 and the insulating pattern 20 has a slant angle to reduce light-passing of the liquid crystal layer caused by the ruggedness formed on the interlayer insulating film 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device and a manufacturing method thereof, and more particularly to a liquid crystal display device in which liquid crystal molecules of a liquid crystal layer are subjected to alignment treatment and a manufacturing method thereof.

[0002]

2. Description of the Related Art An active matrix type liquid crystal display device has, as its basic structure, an active matrix substrate having a plurality of pixels serving as a display unit for displaying an image arranged in a matrix, a counter electrode, a color filter and the like. It has a counter substrate which is arranged to face the active matrix substrate with a proper gap, and a liquid crystal layer sandwiched between these substrates.

The active matrix substrate has a plurality of scanning wirings and signal wirings which are formed in an intersecting state on an insulating substrate such as a glass substrate. At the intersection where each scanning wiring and the signal wiring are close to each other, the scanning signal applied to the scanning wiring is turned on at a position near the intersection.
A switching element such as a thin film transistor which is turned off is provided. Then, an interlayer insulating film having a predetermined film thickness is provided on the scanning wirings, the signal wirings, and the switching elements, and a signal voltage from each signal wiring is turned on / off by turning on / off each switching element. Pixel electrodes to which are respectively input are provided. The pixel electrodes are arranged in a matrix so as to correspond to the intersections of the scanning lines and the signal lines formed on the insulating substrate, and the size of each pixel is defined by the size of the pixel electrode. To be done.

An alignment film that has been subjected to a rubbing treatment is provided on each of the surfaces of the substrates that sandwich the liquid crystal layer, facing the liquid crystal layer. It is controlled to be oriented in the same direction.

[0005]

The performance of a liquid crystal display device is shown by using brightness and contrast as indexes. In order to improve the brightness, it is necessary to enlarge the pixel electrode of each pixel to increase the area for transmitting light. On the other hand, in order to improve the contrast, it is necessary to prevent the generation of a region through which light is emitted in the case of black display. For this reason, a light-shielding film or the like that does not transmit light is provided in the region through which light passes.

As described above, in the liquid crystal display device, in order to improve the contrast while maintaining the brightness,
It is important to prevent the generation of a region where light leakage occurs without increasing the light-shielding region that does not transmit light.

In the active matrix substrate of the active matrix type liquid crystal display device having the above structure, since the scanning wiring and the like having a predetermined thickness are formed on the insulating substrate, the interlayer insulating film on which the pixel electrode is formed is formed. Unevenness is formed on the surface. When the uneven shape is formed on the surface of the interlayer insulating film as described above, when the rubbing process is performed on the alignment film formed after the pixel electrode is formed, the uniform alignment process cannot be performed and the unevenness is generated. In the formed region, the alignment force of the liquid crystal layer is lowered, the light transmittance is different from that in other regions when no voltage is applied, and there is a problem that light leakage occurs.

FIG. 6 is a schematic cross-sectional view showing an active matrix substrate for explaining the problems caused by the active matrix substrate having the concavo-convex shape formed on the pixel electrodes.

The active matrix substrate 1 has an insulating substrate 2, and a plurality of signal electrodes 3 which are parallel to each other are provided on the insulating substrate 2 at a predetermined equal interval d. An interlayer insulating film 4 is formed on the insulating substrate 2 so as to have a substantially uniform film thickness over the entire surface, and the pixel electrodes 5 are respectively arranged on the interlayer insulating film 4 so as to be located between the signal electrodes 3. It is provided. A liquid crystal layer 6 filled with liquid crystal molecules is formed on the interlayer insulating film 4 provided with the pixel electrode 5.
Is provided. Here, for ease of understanding, only the signal wiring 3, the interlayer insulating film 4, and the pixel electrode 5 formed on the insulating substrate 2 are shown. That is, FIG. 6 shows that the signal wiring 3 is provided directly on the insulating substrate 2, but in reality, the respective components such as the scanning wiring and the switching elements are provided on the insulating substrate 2 shown in FIG. It is provided below the wiring 3.

As shown in FIG. 6, in this active matrix substrate 1, since each signal wiring 3 formed on the insulating substrate 2 has a predetermined thickness h, the portion where each signal wiring 3 is formed is formed. The surface of the corresponding interlayer insulating film 4 is a protruding region protruding by a height h from the surroundings. Also,
The surface of the interlayer insulating film 4 corresponding to each signal wiring 3 in which each signal wiring 3 is not formed is a flat region formed flat. In the protruding region adjacent to the flat region, a slope region is formed that is gradually lowered toward the flat region, so that the flat region has a length along the interval d of each signal line 3 that is longer than the interval d. It's getting shorter. The inclination angle of the inclined region becomes gentle as it moves away from the flat region, but the inclination angle becomes steep in the vicinity of the flat region.

Incidentally, a plurality of scanning wirings (not shown) provided at right angles to the respective signal wirings 3 also cause an uneven shape on the interlayer insulating film.

FIG. 7 shows liquid crystal molecules 7 of the liquid crystal layer 6 when such an uneven shape is formed on the interlayer insulating film 4.
It is a schematic diagram explaining the orientation state of.

Each liquid crystal molecule 7 of the liquid crystal layer 6 has an interlayer insulating film 4
As shown in FIG. 7, due to the uneven surface, particularly the inclined region 4b, the liquid crystal molecules 7 on the flat region 4b are oriented at an inclination angle different from that of the liquid crystal molecules 7 on the flat region 4b. It Therefore, when no voltage is applied, the light transmittance is different from that of the other regions, and light leakage may occur on the inclined region 4b, which may reduce the contrast.

Japanese Unexamined Patent Publication No. 2001-66635 discloses a method of flattening an interlayer insulating film formed on each wiring.

FIG. 8 is a sectional view schematically showing the structure of the active matrix substrate described in this publication.
This active matrix substrate 1 has an insulating substrate 2, and a plurality of signal electrodes 3 which are parallel to each other are provided on the insulating substrate 2 at a predetermined equal interval d. An interlayer insulating film 4 is formed on the insulating substrate 2 so as to have a substantially uniform film thickness over the entire surface, and the pixel electrodes 5 are respectively arranged on the interlayer insulating film 4 so as to be located between the signal electrodes 3. It is provided.

Here, in order to avoid complication of the drawing, only the interlayer insulating film 4, the pixel electrode 5 and the like formed above the signal wiring 3 formed on the insulating substrate 2 are shown, and the insulating substrate 2 is shown. Although it is assumed that the signal wiring 3 is directly formed on the upper side, in actuality, each structure such as the scanning wiring and the switching element is provided on the insulating substrate 2 below the signal wiring 3.

In the active matrix substrate 1 described in this publication, as shown in FIG. 8, insulation having the same thickness as each signal wiring 3 is provided between each signal wiring 3 formed on the insulating substrate 2. The film pattern 6 is formed, and the surface of the interlayer insulating film 4 formed on the insulating substrate 2 is flattened by the insulating film pattern 6.

An insulating film pattern 6 is similarly provided between a plurality of scanning wirings (not shown) provided orthogonally to the respective signal wirings 3.

As described above, since the surface of the interlayer insulating film 4 is flattened, the alignment film (not shown) provided on the interlayer insulating film 4 is caused by the uneven shape on the surface of the interlayer insulating film 4. Alignment failure is prevented, and deterioration of display quality when no voltage is applied is prevented.

However, in the active matrix substrate 1 described in this publication, alignment gaps of liquid crystal molecules occur due to gaps between the pixel electrodes 5 arranged adjacent to each other on the interlayer insulating film 4, causing light leakage. May occur.

FIG. 9 shows the interlayer insulating film 4 as shown in FIG.
FIG. 3 is a schematic diagram showing an alignment state of liquid crystal molecules 7 of a liquid crystal layer 6 when a signal voltage is applied to a pixel electrode 5 of an active matrix substrate 1 having a flat upper surface.

As shown in FIG. 9, in this active matrix substrate 1, when a signal voltage is applied to one of the adjacent pixel electrodes 5, a boundary portion 5 between the adjacent pixel electrodes 5 is formed.
In a, a potential line which is influenced by the lateral electric field from the pixel electrode 5 to which the signal voltage is applied and converges to the boundary portion 5a in the vicinity of the boundary portion 5a as shown by a solid line k in the figure. Occur. Therefore, the liquid crystal molecules 7 of the liquid crystal layer 6 existing in the vicinity of the boundary portion 5a are inclined to the boundary portion 5a side in accordance with this potential line, and are different from the liquid crystal molecules 7 on other regions of the pixel electrode 5. It will have different angles. As a result, there is a possibility that a light leakage region 8 in which light leakage occurs occurs in a region on the pixel electrode 5 which is close to the boundary portion 5a.

In the boundary portion 5a of each pixel electrode 5 formed for each pixel, each signal wiring 3 is provided in a size corresponding to the size of the light passing area 8 generated in the boundary portion 5a. Alternatively, by providing a separate light-shielding film, light leakage is prevented and the contrast is improved.

FIG. 4 shows the distance (hereinafter referred to as a cell gap) between the pixel electrode 5 formed on the most liquid crystal layer 6 side portion of the active matrix substrate 1 and the counter substrate and the width of the light leakage region 8. It is a graph which shows the relationship of.

Referring to the graph of FIG. 4, as the cell gap increases, the width of the light passage region 8 increases, so that the cell gap is preferably small.

For example, referring to the graph of FIG. 4, when the cell gap is 3.0 μm, the width of the light passing area is 5.0 μm, and when the cell gap is 2.5 μm, the width of the light passing area is 4. It is 0 μm. Therefore, in this case, by reducing the cell gap from 3.0 μm to 2.5 μm, the width of the light leakage region can be reduced from 5.0 μm to 4.0 μm by 1.0 μm.

However, since the optimum value of the cell gap is determined by the type of the liquid crystal molecules 7 filled in the liquid crystal layer 6,
When the interlayer insulating film 4 is flattened and the cell gap on the boundary 5a between the pixel electrodes 5 is the same as the cell gap on the other region, the cell gap on the boundary 5a is also different. There is a possibility that the cell gap becomes larger as in the area of (1) and the light leakage area 8 due to the potential line distribution generated at the boundary portion 5a between the pixel electrodes 5 becomes larger and the contrast is lowered.

In order to improve the contrast by forming a light-shielding region that covers the entire light-through region 8 against the occurrence of such a large light-through region 8, the active matrix substrate 1 is formed by the large-sized light-shielding region. The area through which light is transmitted is reduced as a whole, which may reduce the brightness of the entire liquid crystal display device.

Therefore, in the active matrix type liquid crystal display device of the above publication, there is a problem in that it is not easy to improve the contrast while maintaining the brightness, because the contrast is lowered by the light leakage generated when the voltage is applied.

The present invention has been made in order to solve the above-mentioned problems. The problem of light leakage is solved in both the state where a voltage is applied and the state where no voltage is applied, and the performances of brightness and contrast are improved. An object of the present invention is to provide an improved liquid crystal display device and a manufacturing method thereof.

[0031]

In order to solve the above problems, a liquid crystal display device according to the present invention comprises an active matrix substrate in which a plurality of scanning wirings and a plurality of signal wirings are arranged in an intersecting state on an insulating substrate, A counter substrate arranged to face the active matrix substrate with a predetermined gap,
A liquid crystal display device having a liquid crystal layer sandwiched between the active matrix substrate and a counter substrate, wherein the active matrix substrate has a film thickness of each wiring between each wiring of the scanning wiring and the signal wiring. The thin insulating film pattern and the wiring and the insulating pattern are provided on the insulating substrate so as to cover the wiring and the insulating pattern. A flat region formed flat, an interlayer insulating film in which a sloped region is formed gradually higher between the protruding region and the flat region as the distance from the flat region increases, and a flat region on the interlayer insulating film. And a pixel electrode provided so as to partially overlap the signal line in the protruding region.

In the liquid crystal display device of the present invention, the projecting region of the interlayer insulating film projects from the flat region so as to reduce the width of the light leakage region that occurs when a voltage is applied to the pixel electrode in the liquid crystal layer. Is preferred.

In the above liquid crystal display device of the present invention, the tilted region of the interlayer insulating film has a tilt angle at which light leakage of the liquid crystal layer due to the uneven shape formed in the interlayer insulating film is reduced. Is preferred.

In the above liquid crystal display device of the present invention, it is preferable that the inclined region of the interlayer insulating film has an inclination angle of 15 ° or less.

In the above liquid crystal display device of the present invention, it is preferable that the insulating film pattern is formed of a transparent film having a refractive index of 1.4 to 1.95.

The method of manufacturing a liquid crystal display device according to the present invention is the method of manufacturing a liquid crystal display device according to the present invention, wherein each of the signal wiring and the scanning wiring has a constant thickness on the insulating substrate. A step of forming, an step of forming an insulating film pattern thinner than each wiring between the wirings, a step of forming an interlayer insulating film so as to cover the wirings and the insulating film pattern, the interlayer insulation And a step of forming a pixel electrode in a flat region on the film so as to partially overlap the protruding region.

[0037]

BEST MODE FOR CARRYING OUT THE INVENTION The liquid crystal display device and the manufacturing method thereof according to the present invention will be described in detail below.

First, the outline of the liquid crystal display device of the present invention will be described.

The liquid crystal display device of the present invention has an active matrix substrate in which a plurality of pixels, which are display units when displaying an image, are arranged in a matrix, and an active matrix substrate having counter electrodes, color filters and the like. It has a basic structure of an active matrix type including counter substrates which are arranged to face each other with a certain interval, and a liquid crystal layer which is sandwiched between these substrates.

FIG. 1 is a plan view showing a main part of an active matrix substrate of a liquid crystal display device of the present invention. In addition,
In this embodiment, in order to facilitate understanding of the features of the present invention, FIG. 1 shows only one pixel portion surrounded by two scanning wirings and two signal wirings. A large number of pixels are formed on the active matrix substrate.

The active matrix substrate used in the liquid crystal display device of the present invention has a plurality of scanning wirings 13 and signal wirings 12 which are formed in an intersecting state on an insulating substrate such as a glass substrate. A thin film transistor (not shown; hereinafter referred to as a TFT), which is a switching element that is turned on / off by a scanning signal applied to the scanning wiring 13, is provided in the vicinity of the intersection of each scanning wiring 13 and the signal wiring 12. It is provided. Then, an interlayer insulating film having a predetermined film thickness is provided on the insulating substrate so as to cover the scanning wirings 13, the signal wirings 12, and the TFTs. Contact holes reaching the drain electrodes of the respective TFTs are formed in the interlayer insulating film at positions corresponding to the respective drain electrodes. The pixel electrodes 15 connected to the drain electrodes of the respective TFTs through the contact holes are provided on the interlayer insulating film. The pixel electrodes 15 are arranged in a matrix so as to correspond to the portions surrounded by the scanning wirings 13 and the signal wirings 12 formed on the insulating substrate. It is specified by the size of each.

Further, the gate electrode of each TFT arranged in each pixel is connected to a predetermined scanning wiring 13, and a scanning signal is applied to the scanning wiring 13 to control ON / OFF of the gate electrode. To be done. Further, the source electrode of the TFT is connected to a predetermined signal wiring 12, and the signal voltage applied to the source electrode is applied to the pixel electrode 15 via the drain electrode when the gate electrode is turned on.

An alignment film that has been subjected to a rubbing treatment is provided on each of the surfaces of the two substrates that sandwich the liquid crystal layer, facing the liquid crystal layer. Each liquid crystal molecule of the liquid crystal layer is formed by the alignment film of each substrate. , Are controlled to be oriented in a predetermined direction.

2 (a) to 2 (d) are cross-sectional views showing the method of manufacturing the active matrix substrate for each step, and FIG. 2 (d) shows a state in which the manufacturing step is completed. It corresponds to the cross-sectional view taken along the line AA 'in FIG.

In FIGS. 2A to 2D, signal wiring is provided directly on the substrate in order to avoid complication of the drawing.
Although the structure such as the interlayer insulating film and the pixel electrode is shown provided on the signal wiring 12, the scanning wiring 13 and the TFT are actually provided in the lower layer portion of the substrate on which the signal electrode is provided.
Etc. are provided. Since the scanning wirings 13 are provided below the signal wirings described below so as to be orthogonal to the signal wirings, detailed description thereof will be omitted.

The active matrix substrate 10 of the liquid crystal display device of the present invention is, as shown in FIGS. 1 and 2 (d),
A plurality of signal wirings 12 are arranged on the insulating substrate 11 so as to be parallel to each other. Each signal wiring 12 has a constant thickness. An insulating film pattern 20 that is substantially rectangular in a top view and is formed to be thinner than the signal wirings 12 is provided between the adjacent signal wirings 12 and between the adjacent scanning wirings 13. This insulating film pattern 20
Between the signal wirings 12 and the scanning wirings 13,
It is provided so as to have an equal distance from the side edges of each signal wiring 12 and each scanning wiring 13.

An interlayer insulating film 14 is provided on each signal wiring 12 and the insulating film pattern 20 so as to have a substantially uniform film thickness over the entire surface of the substrate.

Each signal wiring 1 provided on the insulating substrate 11
2 and the insulating film pattern 20 have different thicknesses. For this reason, the surface of the interlayer insulating film 14 is formed on the signal wiring 12 so as to have a height slightly higher than that of other portions.
4a, and in the portion on the insulating film pattern 20,
Since the insulating film pattern 20 is provided flat, it becomes a flat region 14b that is flat. Further, the surface of the interlayer insulating film 14 corresponding to the gap between the insulating film pattern 20 and the signal wiring 12 is continuously and continuously increased from the height of the flat region 14b to the height of the protruding region 14b as the distance from the flat region 14b increases. It is an inclined region 14c that is inclined to.

FIG. 3 is a definition diagram for defining the inclination angle of the inclined region 14c.

As shown in FIG. 3, a distance D is formed between each signal wiring 12 and the insulating film pattern 20, and each signal wiring 12 is formed thicker than the insulating film pattern 20 by a thickness t. If the tilted region 14c is
Assuming that the inclination angle is θ with respect to the surface of No. 1, the inclination angle θ has a relational expression of tan θ = t / D (1) between the thickness t and the distance D.

In the active matrix substrate 10 used in the liquid crystal display device of the present invention, the distance D and the thickness t are set so that the inclination angle θ of the inclined region 14c on the surface of the interlayer insulating film 14 is 15 degrees or less. ing.

A pixel electrode 15 is provided on the interlayer insulating film 14 formed to have such an uneven surface. The size of the pixel electrode 15 defines the size of each pixel which is a display unit of image display, and covers the entire surface of the flat region 14b and the inclined region 14c which are between the signal lines 12 on the interlayer insulating film 14. Thus, the peripheral portion is provided so as to overlap the protruding region 14 a corresponding to the signal wiring 12. In addition, in the active matrix substrate 10, the scanning wiring 13 is arranged in the lower layer portion of the insulating substrate 11 on which the signal wiring 12 is provided, as shown by a broken line in the figure, and the signal wiring 1 of the pixel electrode 15 is arranged.
The side edges in the direction along 2 are provided so as to overlap each scanning wiring 13.

In the present invention, the protruding region 14b is formed on the surface of the interlayer insulating film 14 so as to be slightly higher than the other regions on each signal line 12, and the protruding region 14b is formed.
In, the cell gap is formed smaller than other regions. Therefore, as shown in the graph of FIG. 4, it is possible to reduce the width of the light leakage region generated at the boundary between the pixel electrodes 15.

On the other hand, in this case, a predetermined inclination angle θ is formed between the protruding region 14a and the flat region 14b on the interlayer insulating film 14.
In the case where the inclined region 14c having the following is formed and the inclination angle θ of the inclined region 14c is not appropriate,
The liquid crystal molecules present on the inclined region 14c are oriented in a different direction from the liquid crystal molecules present in other regions, and light leakage occurs due to the inclination angle θ of the inclined region 14c and the contrast is lowered. May occur.

FIG. 5 is a graph showing the relationship between the inclination angle θ formed in the inclined region 14c and the contrast.

Referring to this graph, the inclination angle θ is
When the inclination angle θ is 15 ° or less, the same degree of contrast as that of the inclination angle θ = 0 ° can be obtained, but when the inclination angle θ exceeds 15 °, the contrast sharply decreases.

Therefore, the inclination angle θ formed in the inclined region 14c is preferably 15 degrees or less.

In this case, if the above equation (1) is modified,
If D = t / tan θ and θ <15 °,
Since tan θ increases as θ increases, ta
From n15 ° = 0.27 and the above equation (1), the relational expression of D> t / tan15 ° = t / 0.27≈3.7t (2) is obtained. If the distance D and the thickness difference t are set within the range satisfying the expression (2) by the expression (2), the deterioration of the contrast can be suppressed.

Next, a method of manufacturing the active matrix substrate 10 used in the liquid crystal display device of the present invention having the above-mentioned structure will be described step by step with reference to FIGS.

First, as shown in FIG. 2A, the signal wiring 12 is formed on the insulating substrate 11 with an Al-based metal material or the like to have a film thickness of about several thousand Å.

Next, as shown in FIG. 2B, an insulating film is formed between the signal wirings 12 so as to be thinner than the signal wirings 12 by a predetermined dimension, and then the plane is similar to that of each pixel. The insulating film pattern 20 is formed by patterning into a substantially rectangular shape. As described above, in the insulating film pattern 20, the distance D between the signal wiring 12 and the insulating film pattern 20 and the height difference t between the signal wiring 12 and the insulating film pattern 20 satisfy the above equation (2). Set to do.

In this embodiment, the film thickness of the signal wiring 12 is 600 nm and the film thickness of the insulating film pattern 20 is 300 n.
m. In this case, the signal wiring 12 and the insulating film pattern 2
The thickness difference t of 0 is 0.3 μm, and the distance D is D> 3.7 × t = 3.7 × 0.3 (μm) ≈1.1 μm from the above formula (1). . In the present embodiment, the distance D is 1.4 μm.

Further, the insulating film pattern 20 needs to be a transparent film when the liquid crystal display device is a transmissive type, and in this case, the refractive index of the transparent film is 1.4 to.
It is preferably about 1.95. SiN _x , SiO _x, or the like is used as the transparent insulating film. In this embodiment, a SiO ₂ film is used.

Next, as shown in FIG. 2C, the interlayer insulating film 14 is uniformly formed over the entire surface of the signal wiring 12 and the insulating film pattern 20. The interlayer insulating film 14 may be formed of the same material as the insulating film pattern 20, or may be formed of a different material. In the present embodiment, the insulating film pattern and the oxide film SiO ₂ film, which is the same material as 20, are formed.

The thickness of the interlayer insulating film 14 is
Protruding region 14a on the signal wiring 12 from the flat region 14b of
To form an inclined region 14c continuous with the distance D
It is necessary to have a thickness of ½ times or more. In the present embodiment, since the insulating film pattern 20 is patterned with the distance D = 1.4 μm as described above, the thickness of the interlayer insulating film 14 needs to be 700 nm or more. In the present embodiment, the thickness of the interlayer insulating film 14 is set to about 1.1 μm.

By performing these steps, the thickness difference t between the protruding region 14a on the signal wiring 12 and the flat region 14b on the insulating film pattern 20 on the interlayer insulating film 14 is 30.
It is formed so as to be 0 μm, and the inclination angle θ of the inclined region 14c is formed to be 15 ° or less.

Next, as shown in FIG. 2D, ITO
(Indium tin oxide) to the interlayer insulating film 1
4 is provided on the entire surface, and then the flat region 14b and the inclined region 14c of the interlayer insulating film 14 and the protruding region 14a are formed.
Pattern is formed so as to partially overlap with the pixel electrode 15
And

After that, the active matrix substrate 10 is completed through the steps of applying an alignment film and then performing a rubbing process in the same manner as a known method.

Then, the active matrix substrate 10 manufactured through the above steps is bonded to the counter substrate with an appropriate gap, and a liquid crystal material is injected between both substrates to form a liquid crystal layer. The desired active matrix type liquid crystal display device is obtained by further performing necessary steps such as a step of sealing the substrate and a step of attaching a polarizing plate to the outside of both substrates.

In the liquid crystal display device completed through the above steps, in the active matrix substrate, the boundary portion of each pixel electrode 15 is formed on the protruding region 14a of the interlayer insulating film 14, and the protruding region 14a is flat. Area 14b
Since it is formed 300 nm higher than that, the light leakage width can be reduced by about 0.9 μm with reference to FIG. That is, the effective opening area of the pixel electrode portion is 0.9
It could be increased by μm.

As a result, when the pixel electrode 15 which determines the size of one pixel has a size of 14 μm × 14 μm and each pixel is arranged at a pitch of 20 μm, the aperture ratio is about 50%. On the other hand, the aperture ratio is about 55% because the pixel electrode 15 spreads 0.9 μm in each direction.
Therefore, the aperture ratio can be improved by about 5%.

Further, according to the present invention, since the height of the interlayer insulating film 14 is thickly formed as the protruding region 14a only at the boundary of each pixel electrode 15, the liquid crystal material filled in the liquid crystal layer is formed in other regions. Since the cell gap is optimum for the above, it does not adversely affect the image display.

Moreover, the protruding region 14a of the interlayer insulating film 14 is formed.
Since the tilt angle θ of the tilted region 14c formed between the flat region 14b and the flat region 14b is set to 15 degrees or less, it is possible to prevent light leakage due to the tilted region 14c having the tilt angle θ.

As described above, in the liquid crystal display device of the present invention,
Both brightness and contrast can be improved.

[0075]

As described above, in the liquid crystal display device of the present invention, the insulating film patterns formed to be thinner than the thickness of each wiring are formed between the wirings, and the wirings and the insulating film pattern are formed on each wiring. The interlayer insulating film provided is formed to have a high height so that the protruding region on each wiring can reduce the width of the light-excluding region generated when a voltage is applied to the pixel electrode in the liquid crystal layer. An inclined region which is located above the film pattern is formed at an inclination angle that reduces light leakage of the liquid crystal layer due to the uneven shape formed in the interlayer insulating film. Therefore, in the liquid crystal display device of the present invention, it is possible to reduce the width of the light leakage region generated by the lateral electric field at the boundary between the adjacent pixel electrodes, and also to prevent light leakage caused by the uneven shape on the interlayer insulating film. The liquid crystal display device can be prevented and the brightness and the contrast can be improved.

[Brief description of drawings]

FIG. 1 is a plan view showing an active matrix substrate of a liquid crystal display device of the present invention.

FIGS. 2A to 2D are cross-sectional views showing respective steps of a method for manufacturing an active matrix substrate of a liquid crystal display device of the present invention.

FIG. 3 is a definition diagram for defining a tilt angle formed in a tilt region.

FIG. 4 is a graph showing the relationship between the distance between the pixel electrode formed on the innermost portion of the active matrix substrate and the counter substrate and the width of the light leakage region.

FIG. 5 is a graph showing a relationship between a tilt angle θ formed in a tilt region and contrast.

FIG. 6 is a schematic view showing a problem caused by an active matrix substrate having a concavo-convex shape formed on a pixel electrode in a conventional liquid crystal display device.

FIG. 7 is a schematic view showing an alignment state of liquid crystal molecules in a liquid crystal layer when a concavo-convex shape is formed on an interlayer insulating film.

FIG. 8 is a schematic view showing a conventional active matrix substrate in which the surface of an interlayer insulating film is flattened.

FIG. 9 is a schematic diagram showing an alignment state of liquid crystal molecules in a liquid crystal layer when a signal voltage is applied to a pixel electrode of the active matrix substrate.

[Explanation of symbols]

10 Active matrix substrate 11 board 12 signal wiring 13 Scan wiring 14 Interlayer insulation film 15 pixel electrodes 20 Insulating film pattern

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Claims (6)

[Claims] 1. An active matrix substrate in which a plurality of scanning wirings and a plurality of signal wirings are arranged in an intersecting state on an insulating substrate, a counter substrate which is arranged to face the active matrix substrate with a predetermined gap, and A liquid crystal display device comprising a liquid crystal layer sandwiched between an active matrix substrate and a counter substrate, wherein the active matrix substrate has a film thickness of each wiring between each wiring of the scanning wiring and the signal wiring. The thin insulating film pattern is provided on the insulating substrate so as to cover each wiring and the insulating pattern, and the surface corresponding to each wiring has a highly protruding region and the surface corresponding to the insulating film pattern. A flat region formed flat, and an inclined region formed between the protruding region and the flat region and gradually increasing in height with increasing distance from the flat region. And a pixel electrode provided in a flat region on the interlayer insulating film, a part of which is in the protruding region so as to overlap with the signal wiring, respectively. Liquid crystal display device. 2. The projecting region of the interlayer insulating film projects from a flat region so as to reduce the width of a light leakage region that occurs when a voltage is applied to the pixel electrode in the liquid crystal layer. Liquid crystal display device. 3. The liquid crystal according to claim 1, wherein the tilted region of the interlayer insulating film has a tilt angle that reduces light leakage of the liquid crystal layer due to the uneven shape formed in the interlayer insulating film. Display device. 4. The liquid crystal display device according to claim 3, wherein the inclination angle of the inclined region of the interlayer insulating film is 15 ° or less. 5. The insulating film pattern has a refractive index of 1.4.
The liquid crystal display device according to claim 1, wherein the liquid crystal display device is formed of a transparent film having a thickness of about 1.95. 6. The method of manufacturing a liquid crystal display device according to claim 1, wherein a step of forming each of the signal wiring and the scanning wiring with a constant thickness on the insulating substrate; A step of forming an insulating film pattern formed thinner than each wiring, a step of forming an interlayer insulating film so as to cover each wiring and the insulating film pattern, and a part of a flat area on the interlayer insulating film. And a step of forming a pixel electrode so that the pixel electrode overlaps with the projecting region, the manufacturing method of the liquid crystal display device.