JP2001343647A - Liquid crystal display device and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device with high display quality and a method for manufacturing the same. SOLUTION: The liquid crystal display device carries out displaying by applying voltage to a liquid crystal layer which is in a vertical aligned state with no voltage applied to the first and second electrodes. The first electrode is provided with a lower conductive layer, a dielectric layer covering at least a part of the lower conductive layer and an upper conductive layer arranged on the liquid crystal layer side of the dielectric layer. The upper conductive layer is provided with conductive layer opening parts and further the lower conductive layer is arranged opposite to at least a part of the conductive layer opening part via the dielectric layer. The dielectric layer is provided with a recessing part in a region corresponding to the conductive layer opening part. The dielectric layer includes a second dielectric layer formed on a first dielectric layer and the recessing part has an opening part formed on the first dielectric layer.

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 method of manufacturing the same, and more particularly, to a liquid crystal display device having a wide viewing angle characteristic and displaying a high display quality and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, a thin and lightweight liquid crystal display device has been used as a display device for a display of a personal computer or a display section of a portable information terminal device.
However, the conventional twisted nematic type (TN)
Type) and super twisted nematic type (STN type) liquid crystal display devices have the disadvantage of a narrow viewing angle, and various technical developments have been made to solve them.

As a typical technique for improving the viewing angle characteristics of a TN type or STN type liquid crystal display device, there is a method of adding an optical compensator. As another method, there is a lateral electric field method in which an electric field in a direction horizontal to the surface of the substrate is applied to the liquid crystal layer. This lateral electric field type liquid crystal display device has been mass-produced in recent years and has attracted attention. Further, as another technique, a nematic liquid crystal material having a negative dielectric anisotropy is used as a liquid crystal material, and a vertical alignment film is used as an alignment film.
mation of vertical aligned phase). this is,
Voltage controlled birefringence (ECB)
It is one of the types of (fringence) system, and controls the transmittance by utilizing the birefringence of liquid crystal molecules.

[0004]

However, although the lateral electric field method is one of the effective methods as a technique for widening the viewing angle, the production margin in the manufacturing process is remarkably narrower than that of a normal TN type, so that it is stable. There is a problem that production is difficult. This is because gap unevenness between substrates and deviation of the transmission axis (polarization axis) of the polarizing plate with respect to the alignment axis of liquid crystal molecules greatly affect display luminance and contrast ratio. In order to achieve stable production, further technological development is required.

In order to perform uniform display without display unevenness in a DAP type liquid crystal display device, it is necessary to control alignment. As a method of controlling the alignment, there is a method of performing an alignment treatment by rubbing the surface of the alignment film. However, when a rubbing treatment is performed on the vertical alignment film, rubbing streaks are easily generated in a displayed image, which is not suitable for mass production.

On the other hand, as a method of controlling the alignment without performing a rubbing process, a method of forming a slit (opening) in an electrode to generate an oblique electric field and controlling the alignment direction of liquid crystal molecules by the oblique electric field. (For example, JP-A-6-30136). However, if a configuration in which an oblique electric field is generated by forming a slit (opening) in the electrode is adopted, a sufficient voltage cannot be applied to the liquid crystal layer in a region corresponding to the slit formed in the electrode. As a result, there is a problem that the alignment of the liquid crystal molecules in the liquid crystal layer in the region corresponding to the slit cannot be sufficiently controlled, resulting in a loss of transmittance when a voltage is applied.

The present invention has been made to solve the above problems, and has as its object to provide a liquid crystal display device having high display quality and a method of manufacturing the same.

[0008]

A liquid crystal display device according to the present invention comprises a first substrate, a second substrate, the first substrate and the second substrate.
A first electrode provided on the liquid crystal layer side of the first substrate, and a first electrode provided on the second substrate via the liquid crystal layer. And a plurality of picture element regions each defined by the opposing second electrode, and in each of the plurality of picture element regions, the liquid crystal layer is provided between the first electrode and the second electrode. It takes a vertical alignment state when no voltage is applied, and
An orientation state is changed according to a voltage applied between the first electrode and the second electrode, wherein the first electrode includes a lower conductive layer, a first dielectric layer having a first opening, A second dielectric layer provided on the lower conductive layer and the first dielectric layer, and an upper conductive layer provided on the liquid crystal layer side of the second dielectric layer, wherein the upper conductive layer Has at least one conductive layer opening, the lower conductive layer is provided to face at least a part of the at least one conductive layer opening via the second dielectric layer, and The first opening is provided corresponding to the conductive layer opening, and the height of the surface of the second dielectric layer located in the conductive layer opening is the upper conductive layer provided. Having a configuration lower than the height of the surface of the second dielectric layer in the region where
Thereby, the above object is achieved.

[0009] The first dielectric layer may be provided on the lower conductive layer, and the first opening may be formed to expose a part of the lower conductive layer. .

[0010] The first dielectric layer may be provided below the lower conductive layer, and the lower conductive layer may be formed to cover the first opening.

The first substrate is provided under the lower conductive layer,
It may be configured such that a third dielectric layer having a second opening in a region corresponding to the conductive layer opening is further provided.

[0012] The first substrate may further include a thin film transistor, and the third dielectric layer may also serve as a gate insulating film of the thin film transistor.

The method for manufacturing a liquid crystal display device according to the present invention comprises:
A first substrate, a second substrate, and a liquid crystal layer provided between the first substrate and the second substrate; and a first electrode provided on the liquid crystal layer side of the first substrate. A second electrode provided on the second substrate and opposed to the first electrode via the liquid crystal layer.
A plurality of picture element regions each defined by an electrode, wherein the first electrode has a lower conductive layer, a first dielectric layer having a first opening, the lower conductive layer and the first dielectric layer. A second dielectric layer provided on the layer, and an upper conductive layer provided on the liquid crystal layer side of the second dielectric layer, wherein the upper conductive layer has at least one conductive layer opening. The method of manufacturing a liquid crystal display device, wherein the lower conductive layer is provided so as to face at least a part of the opening of the at least one conductive layer via the second dielectric layer. The step of forming one electrode includes forming a lower conductive layer on a substrate, forming a first dielectric layer having a first opening on the substrate, and forming the lower conductive layer and the first conductive layer on the substrate.
Forming a second dielectric layer on the dielectric layer, the surface height of a region corresponding to the first opening being lower than the surface height of another region; Forming an upper conductive layer having a conductive layer opening on a corresponding region of the second dielectric layer, whereby the object is achieved.

[0014] The first dielectric layer may be formed on the lower conductive layer such that the lower conductive layer is exposed in the first opening.

The lower conductive layer may be formed on the first dielectric layer so as to cover at least the first dielectric layer opening of the first dielectric layer.

The method may further include, before the step of forming the lower conductive layer, a step of forming a third dielectric layer having a second opening on the substrate.

The method may further include forming a thin film transistor on the substrate, wherein the third dielectric layer may be formed to also serve as a gate insulating film of the thin film transistor.

Another method of manufacturing a liquid crystal display device according to the present invention comprises a first substrate, a second substrate, the first substrate and the second substrate.
A first electrode provided on the liquid crystal layer side of the first substrate, and a first electrode provided on the second substrate via the liquid crystal layer. A plurality of picture element regions each defined by a second opposing second electrode, wherein the first electrode has a lower conductive layer, a dielectric layer covering at least a part of the lower conductive layer, An upper conductive layer provided on the liquid crystal layer side of a body layer, wherein the upper conductive layer has at least one conductive layer opening,
The method for manufacturing a liquid crystal display device, wherein the lower conductive layer is provided to face at least a part of the opening of the at least one conductive layer via the dielectric layer, and forms the first electrode. Forming a lower conductive layer on the substrate, forming a dielectric film on the lower conductive layer, and forming an upper conductive layer having a conductive layer opening on the dielectric film; By partially removing the dielectric film in the opening of the conductive layer using the upper conductive layer as a mask, the height of the surface of the region corresponding to the first opening becomes higher than the height of the surface of the other region. Forming a lower dielectric layer, thereby achieving said object.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an electrode structure of a liquid crystal display device according to the present invention and its operation will be described. Since the liquid crystal display device according to the present invention has excellent display characteristics, it is suitably used for an active matrix type liquid crystal display device. Hereinafter, an embodiment of the present invention will be described for an active matrix type liquid crystal display device using a thin film transistor (TFT). The present invention is not limited to this, and can be applied to an active matrix type liquid crystal display device and a simple matrix type liquid crystal display device using MIM. Hereinafter, embodiments of the present invention will be described by taking a transmissive liquid crystal display device as an example. However, the present invention is not limited to this, and may be applied to a reflective liquid crystal display device or a transflective liquid crystal display device. it can.

In the specification of the present application, the area of the liquid crystal display device corresponding to the "picture element" which is the minimum unit of display is called "picture element area". In a color liquid crystal display device,
The “picture elements” of R, G, and B correspond to one “pixel”. In an active matrix type liquid crystal display device, a picture element region defines a picture element region by a picture element electrode and a counter electrode facing the picture element electrode. In a simple matrix type liquid crystal display device, each region where a column electrode provided in a stripe shape and a row electrode provided so as to be orthogonal to the column electrode cross each other defines a picture element region. Note that, in the configuration in which the black matrix is provided, strictly speaking, of the regions to which the voltage is applied according to the state to be displayed, the region corresponding to the opening of the black matrix corresponds to the pixel region. .

A liquid crystal display device 10 according to an embodiment of the present invention.
FIG. 1 schematically shows a cross section of one pixel region of 0. Hereinafter, a color filter and a black matrix are omitted for simplicity of description. In the following drawings, components having substantially the same functions as the components of the liquid crystal display device 100 are denoted by the same reference numerals, and description thereof will be omitted. Note that, for simplicity, FIG.
Although one pixel area of 00 is shown, as will be described in detail later, the liquid crystal display device according to the present invention may have at least one electrode configuration shown in FIG. 1 in one pixel area.

The liquid crystal display device 100 includes an active matrix substrate (hereinafter, referred to as "TFT substrate") 100a,
Counter substrate (also referred to as “color filter substrate”) 100b
And a liquid crystal layer 30 provided between the TFT substrate 100a and the counter substrate 100b. The liquid crystal molecules 30a of the liquid crystal layer 30 have a negative dielectric anisotropy, and the TFT substrate 1
The liquid crystal layer 30 is formed by a vertical alignment layer (not shown) provided on the surface of the counter substrate 100b on the liquid crystal layer 30 side.
When no voltage is applied to the vertical alignment film, as shown in FIG. At this time, the liquid crystal layer 30 is in a vertical alignment state. However,
The liquid crystal molecules 30a of the liquid crystal layer 30 in the vertical alignment state may be slightly inclined from the normal of the surface of the vertical alignment film (the surface of the substrate) depending on the type of the vertical alignment film and the type of the liquid crystal material. In general, a state in which a liquid crystal molecular axis (also referred to as “axis direction”) is oriented at an angle of about 85 ° or more with respect to the surface of the vertical alignment film is called a vertical alignment state.

The TFT substrate 100a of the liquid crystal display device 100
Has a transparent substrate (for example, a glass substrate) 11 and a pixel electrode 15 formed on the surface thereof. Counter substrate 100
b has a transparent substrate (for example, a glass substrate) 21 and a counter electrode 22 formed on the surface thereof. The alignment state of the liquid crystal layer 30 in each picture element region changes according to the voltage applied to the picture element electrode 15 and the counter electrode 22 arranged so as to face each other via the liquid crystal layer 30. Display is performed using a phenomenon in which the polarization state and the amount of light transmitted through the liquid crystal layer 30 change with the change in the alignment state of the liquid crystal layer 30.

The picture element electrode 15 included in the liquid crystal display device 100
Has a lower conductive layer 12, a dielectric layer 13 covering at least a part of the lower conductive layer 12, and an upper conductive layer 14 provided on the liquid crystal layer 30 side of the dielectric layer. Further, the dielectric layer 13 has a recess 13r corresponding to the opening 14a of the upper conductive layer 14. The liquid crystal display device 10 shown in FIG.
In No. 0, the lower conductive layer 12 is formed in a region including the entire region on the substrate 11 facing the opening 14a (the area of the lower conductive layer 12> the area of the opening 14a).

The configuration of the picture element electrode 15 in the liquid crystal display device of the present embodiment is not limited to the above example,
As shown in the liquid crystal display device 100 'shown in FIG.
The lower conductive layer 12 may be formed in a region on the substrate 11 facing the substrate 4a (the area of the lower conductive layer 12 = the area of the opening 14a). In addition, the liquid crystal display device 10 shown in FIG.
As in 0 ″, the lower conductive layer 12 may be formed in a region on the substrate 11 facing the opening 14a (the area of the lower conductive layer 12 <the area of the opening 14a). That is, the lower conductive layer 12 may be provided so as to face at least a part of the opening 14a via the dielectric layer 13. However, in the configuration in which the lower conductive layer 12 is formed in the opening 14 a (FIG. 2B), any one of the lower conductive layer 12 and the upper conductive layer 14 is placed in a plane viewed from the normal direction of the substrate 11. In some cases, there is a region where no gap exists (a gap region), and a sufficient voltage is not applied to the liquid crystal layer 30 in a region facing the gap region. Therefore, the width of this gap region (W in FIG. 2B) is adjusted so that the orientation of the liquid crystal layer 30 is stabilized.
It is preferable to make S) sufficiently narrow. Preferably, the WS typically does not exceed about 4 μm.

The lower conductive layer 12 and the upper conductive layer 1
The pixel electrode 15 including the pixel electrode 4 may be referred to as a “two-layer electrode”. “Lower layer” and “upper layer” are terms used to express the relative relationship between the two electrodes 12 and 14 with respect to the dielectric layer 13 and limit the spatial arrangement when the liquid crystal display device is used. is not. Further, the “two-layered electrode” does not exclude a configuration having an electrode other than the lower conductive layer 12 and the upper conductive layer 14, and has at least the lower conductive layer 12 and the upper conductive layer 14, which will be described below. Any configuration having an effect is acceptable. Further, the two-layer structure electrode does not need to be a picture element electrode in a TFT type liquid crystal display device, and can be applied to other types of liquid crystal display devices if a two-layer structure electrode is provided for each picture element region. Specifically, for example, if a column electrode (signal electrode) in a simple matrix type liquid crystal display device has a two-layer structure for each picture element region, the column electrode in the picture element region functions as a two-layer structure electrode. .

Next, with reference to FIGS. 1, 3 and 4, the operation of the liquid crystal display device having the two-layer structure electrode will be described in comparison with the operation of the liquid crystal display device having the electrode of another configuration. .

First, the operation of the liquid crystal display device 100 will be described with reference to FIG.
This will be described with reference to FIG.

FIG. 1A shows the orientation state (OFF state) of the liquid crystal molecules 30a in the liquid crystal layer 30 to which no voltage is applied.
Is schematically shown. FIG. 1B schematically shows a state in which the orientation of the liquid crystal molecules 30a has started to change in accordance with the voltage applied to the liquid crystal layer 30 (ON initial state). FIG. 1C schematically shows a state in which the orientation of the liquid crystal molecules 30a changed according to the applied voltage has reached a steady state. FIG. 1 shows an example in which the same voltage is applied to the lower conductive layer 12 and the upper conductive layer 14 constituting the pixel electrode 15 for simplicity. Curves EQ in FIGS. 1B and 1C show equipotential lines EQ.

As shown in FIG. 1A, the picture element electrode 15
When the counter electrode 22 and the counter electrode 22 have the same potential (when no voltage is applied to the liquid crystal layer 30), the liquid crystal molecules 30 in the pixel region
a is oriented perpendicular to the surfaces of both substrates 11 and 21.

When a voltage is applied to the liquid crystal layer 30, FIG.
Equipotential line EQ (perpendicular to electric lines of force) E shown in (b)
A potential gradient represented by Q is formed. The liquid crystal layer 3 located between the upper conductive layer 14 of the picture element electrode 15 and the counter electrode 22
In 0, a uniform potential gradient represented by equipotential lines EQ parallel to the surfaces of the upper conductive layer 14 and the counter electrode 22 is formed. The lower conductive layer 12 and the counter electrode 22 are provided in the liquid crystal layer 30 located above the opening 14 a of the upper conductive layer 14.
, A potential gradient corresponding to the potential difference is formed. At this time,
Since the potential gradient formed in the liquid crystal layer 30 is affected by the voltage drop (capacitance division) by the dielectric layer 13, the equipotential lines EQ formed in the liquid crystal layer 30 correspond to the region corresponding to the opening 14a. (A “valley” is formed in the equipotential line EQ). Since the lower conductive layer 12 is formed in a region facing the opening 14a via the dielectric layer 13, the opening 1
A potential gradient represented by equipotential lines EQ parallel to the surfaces of the upper conductive layer 14 and the counter electrode 22 is also formed in the liquid crystal layer 30 located near the center of 4a (equipotential lines EQ).
"Bottom of the valley"). Edge portion of opening 14a (opening 14
a) EG including the boundary (extension) of the opening a
In the upper liquid crystal layer 30, an oblique electric field represented by an inclined equipotential line EQ is formed.

A torque is applied to the liquid crystal molecules 30a having negative dielectric anisotropy so as to orient the axis direction of the liquid crystal molecules 30a parallel to the equipotential line EQ (perpendicular to the electric force lines). I do. Therefore, the liquid crystal molecules 30 on the edge portion EG
a is inclined (rotated) clockwise at the right edge EG in the figure and counterclockwise at the left edge EG in the figure, as indicated by arrows in FIG. 1B. ,
It is oriented parallel to the equipotential line EQ.

Here, referring to FIG.
The change in the orientation of 0 will be described in detail.

When an electric field is generated in the liquid crystal layer 30, a torque is applied to the liquid crystal molecules 30a having a negative dielectric anisotropy so as to orient the axis of the liquid crystal molecules 30a in parallel with the equipotential line EQ. I do. As shown in FIG. 5A, the liquid crystal molecules 30
When an electric field represented by an equipotential line EQ perpendicular to the axis azimuth of a is generated, the torque for tilting the liquid crystal molecules 30a in the clockwise or counterclockwise direction acts with equal probability. Therefore, as will be described later with reference to FIG. 3, the liquid crystal molecules 30a which receive the clockwise torque are provided in the liquid crystal layer 30 between the electrodes of the parallel plate type arrangement facing each other.
And the liquid crystal molecules 30a receiving a torque in the counterclockwise direction.
And are mixed. As a result, the change to the alignment state according to the voltage applied to the liquid crystal layer 30 may not occur smoothly.

As shown in FIG. 1B, the edge portion EG of the opening 14a of the liquid crystal display device 100 according to the present invention is represented by an equipotential line EQ inclined with respect to the axial direction of the liquid crystal molecules 30a. When an electric field (oblique electric field) is generated, FIG.
As shown in (b), the liquid crystal molecules 30a have the equipotential lines E
It inclines in a direction in which the amount of inclination for becoming parallel to Q is small (counterclockwise in the illustrated example). Further, the liquid crystal molecules 30a located in a region where an electric field represented by an equipotential line EQ perpendicular to the axis direction of the liquid crystal molecules 30a is generated, as shown in FIG.
As shown in (2), the liquid crystal molecules 30a located on the inclined equipotential line EQ are arranged so that the alignment with the liquid crystal molecules 30a located on the inclined equipotential line EQ is continuous (matched).
Incline in the same direction as a. Here, “located on the equipotential line EQ” means “located in the electric field represented by the equipotential line EQ”.

As described above, the alignment changes starting from the liquid crystal molecules 30a located on the inclined equipotential line EQ progress, and when the steady state is reached, the alignment state is schematically shown in FIG. 1 (c). . Since the liquid crystal molecules 30a located near the center of the opening 14a are almost equally affected by the orientation of the liquid crystal molecules 30a at the opposite edge portions EG of the opening 14a, the liquid crystal molecules 30a are perpendicular to the equipotential lines EQ. The liquid crystal molecules 3 are maintained in an alignment state and are located in a region away from the center of the opening 14a.
0a are the liquid crystal molecules 30 at the edge portions EG which are closer to each other.
a of the opening 14a.
A tilted orientation symmetrical with respect to A is formed. This alignment state is perpendicular to the display surface of the liquid crystal display device 100 (substrate 1).
When viewed from the direction perpendicular to the surfaces of the liquid crystal molecules 1 and 21, the liquid crystal molecules 30a are radially aligned with respect to the center of the opening 14a (not shown). Therefore, in the specification of the present application, such an alignment state is referred to as “radial tilt alignment”.
I will call it.

In order to improve the viewing angle dependency of the liquid crystal display device in all directions, it is necessary that the orientation of liquid crystal molecules in each picture element region has a rotational symmetry about an axis perpendicular to the display surface. Is preferable, and it is more preferable to have axial symmetry. Therefore, it is preferable that the openings 14a are arranged such that the orientation of the liquid crystal layer 30 in the picture element region has rotational symmetry (or axial symmetry). When one opening 14a is formed for each picture element area, it is preferable to provide the opening 14a at the center of the picture element area. The opening 14
The shape of a (shape in the layer plane of the liquid crystal layer 30) also preferably has rotational symmetry (axial symmetry), and is preferably a regular polygon such as a square or a circle. Regarding the arrangement when a plurality of openings 14a are formed in the picture element region,
It will be described later.

Further, in the liquid crystal display device 100,
Since the concave portion 13r is formed in the dielectric layer 13 in the opening 14a of the upper electrode 14 of the picture element electrode 15, the thickness d2 of the liquid crystal layer 30 located in the opening 14a depends on the thickness of the upper conductive layer 14. It is thicker by the thickness of the dielectric layer 13 in the recess 13r than the thickness d1 of the liquid crystal layer in the formed region. Further, the voltage applied to the liquid crystal layer 30 located in the opening 14a receives a voltage drop (capacity division) by the dielectric layer 13 in the recess 13r, so that the upper conductive layer (the opening 14a
(Except region) 14 is lower than the voltage applied to liquid crystal layer 30.

Therefore, the dielectric layer 13 in the recess 13r
By adjusting the thickness of the liquid crystal layer 30, the difference in the retardation amount caused by the difference in the thickness of the liquid crystal layer 30 and the difference due to the location of the voltage applied to the liquid crystal layer 30 (applied to the liquid crystal layer in the opening 14a) The relationship between the applied voltage and the retardation can be controlled so as not to depend on the position in the picture element region. More precisely, the birefringence of the liquid crystal layer, the thickness of the liquid crystal layer, the dielectric constant of the dielectric layer and the thickness of the dielectric layer, the thickness of the concave portion of the dielectric layer (the concave portion 13r
), The relationship between the applied voltage and the retardation can be made uniform at a location in the picture element region, and high-quality display can be achieved. In particular, as compared with a transmissive display device having a dielectric layer having a flat surface, the transmittance is reduced (the light transmission is reduced) due to the decrease in the voltage applied to the liquid crystal layer 30 in the region corresponding to the opening 14a of the upper conductive layer 14. There is an advantage that the reduction in utilization efficiency is suppressed.

In the above description, the case where the same voltage is supplied to the upper conductive layer 14 and the lower conductive layer 12 constituting the picture element electrode 15 has been described, but different voltages are applied to the lower conductive layer 12 and the upper conductive layer 14. Is applied, it is possible to increase the variations of the configuration of the liquid crystal display device capable of performing display without display unevenness. For example, by applying to the lower conductive layer 12 a voltage higher than the voltage applied to the upper conductive layer 14 by a voltage drop due to the dielectric layer 13, the voltage applied to the liquid crystal layer 30 is reduced in a location within the pixel region. Can be prevented from being different.

As described with reference to FIGS. 1 (a) to 1 (c), the liquid crystal display device 100 according to the present invention has the two-layer structure electrode 15 for each picture element area. In the liquid crystal layer 30, an electric field represented by an equipotential line EQ having an inclined region is generated. Liquid crystal molecules 3 having negative dielectric anisotropy in liquid crystal layer 30 in a vertical alignment state when no voltage is applied
0a is the liquid crystal molecule 3 located on the inclined equipotential line EQ.
The orientation direction is changed by using the orientation change of 0a as a trigger,
Form a stable radial tilt orientation. Of course, the liquid crystal display devices 100 'and 10 shown in FIGS.
0 ″ operates similarly. However, in the configuration of FIG. 2B, if the gap region WS is too large (for example, if it exceeds about 5 μm), a sufficient voltage is not applied to the edge of the opening 14a, and the region that does not contribute to display is displayed. Sometimes it becomes.

Next, the operation of the conventional typical liquid crystal display device 200 will be described with reference to FIG. FIG.
(C) schematically shows one picture element region of the liquid crystal display device 200.

The liquid crystal display 200 has a picture element electrode 15A and a counter electrode 22 which are arranged to face each other. Each of the picture element electrode 15A and the counter electrode 22 is formed of a single conductive layer having no opening 14a.

As shown in FIG. 3A, when no voltage is applied to the liquid crystal layer 30, the liquid crystal layer 30 takes a vertical alignment state.

The electric field generated by applying a voltage to the liquid crystal layer 30 is applied to the surface of the pixel electrode 15A and the surface of the counter electrode 22 over the entire pixel region as shown in FIG. Are represented by parallel equipotential lines EQ. At this time, the liquid crystal molecules 30a try to change the alignment direction so that the axis direction is parallel to the equipotential line EQ. However, in an electric field in which the axis direction of the liquid crystal molecules 30a is orthogonal to the equipotential line EQ. As shown in FIG. 5A, the direction in which the liquid crystal molecules 30a incline (rotate) is not uniquely determined. The liquid crystal molecules 30a typically start to tilt in various directions under the influence of the local surface state difference of the vertical alignment film. As a result, the alignment state of the liquid crystal molecules 30a differs between the plurality of picture element regions, and the display by the liquid crystal display device 200 becomes a rough display. The orientation state of the liquid crystal layer 30 is shown in FIG.
It takes a longer time to reach the steady state shown in (1) than in the liquid crystal display device 100 of the present invention described above.

That is, the liquid crystal display device 100 of the present invention
Is capable of high-quality display without roughness and has a fast response speed as compared with the conventional liquid crystal display device 200.
It has the feature of.

Next, referring to FIG.
The operation of the liquid crystal display device 300 having the opening 15b in B will be described. The picture element electrode 15B is composed of a single electrode having an opening 15b, and is formed of the lower conductive layer 12 (for example, FIG.
(Refer to FIG. 2) in that the pixel electrode 15 of the liquid crystal display device of the present invention is not provided. The liquid crystal display device 300 generates an oblique electric field in the liquid crystal layer 30 as in the liquid crystal display device disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 6-30136, which has the opening 14a in the counter electrode.

The liquid crystal layer 30 of the liquid crystal display device 300 is shown in FIG.
As shown in (a), when no voltage is applied, a vertical alignment state is obtained. The orientation state of the liquid crystal layer 30 when no voltage is applied is the same as that of the liquid crystal display device of the present invention (FIGS. 1 and 2) and the conventional typical liquid crystal display device (FIG. 3).

When a voltage is applied to the liquid crystal layer 30, FIG.
An electric field represented by the equipotential line EQ shown in FIG. The picture element electrode 15B is connected to the liquid crystal display device 10 of the present embodiment.
0 pixel electrode 15 (see, for example, FIG. 1).
5b, the equipotential line EQ generated in the liquid crystal layer 30 of the liquid crystal display device 200 falls in a region corresponding to the opening 15b and is inclined into the liquid crystal layer 30 on the edge EG of the opening 15b. An oblique electric field represented by the potential line EQ is formed. However, the pixel electrode 15B is formed from a single conductive layer, and does not have a lower conductive layer (the same potential as the pixel electrode) in a region corresponding to the opening 15b, and thus is located on the opening 15b. In the liquid crystal layer 30, there is a region where an electric field is not generated (a region where the equipotential lines EQ are not drawn).

The liquid crystal molecules 30a having a negative dielectric anisotropy placed under an electric field as described above behave as follows.
First, the liquid crystal molecules 30a on the edge EG of the opening 15b
As shown by the arrow in FIG. 4B, the right edge portion EG in the figure is clockwise, and the left edge portion E in the diagram is clockwise.
In G, they are inclined (rotated) in the counterclockwise direction, and are oriented parallel to the equipotential lines EQ. This is the liquid crystal display device 100 of the present embodiment described with reference to FIG.
Or the tilt (rotation) direction of the liquid crystal molecules 30a in the vicinity of the edge EG is uniquely determined, and the stability can cause an alignment change.

However, the edge E of the opening 15b
Since no electric field is generated in the liquid crystal layer 30 located above the region except for G, no torque for changing the alignment is generated. As a result, even if the alignment change of the liquid crystal layer 30 reaches a steady state after a sufficient time has elapsed, as shown in FIG. 4C, the liquid crystal layer 30 is located above the region excluding the edge EG of the opening 15b. The liquid crystal layer 30 remains in the vertical alignment state. Of course, the edge part E
Under the influence of the change in the alignment of the liquid crystal molecules 30a near G, some of the liquid crystal molecules 30a change the alignment.
The orientation of all the liquid crystal molecules 30a in the upper liquid crystal layer 30 cannot be changed. How far from the end of the opening 15b the liquid crystal molecules 30a are affected depends on the thickness of the liquid crystal layer 30 and the physical properties of the liquid crystal material (magnitude of dielectric anisotropy, elastic modulus, etc.). Also depends on the opening 15b.
Is larger than about 4 μm (the length of one side in the case of a square and the diameter in the case of a circle) exceeds about 4 μm, the liquid crystal molecules 30a near the center of the opening 15b do not change their alignment due to an electric field, Maintain orientation. Therefore, the liquid crystal display device 300
The region located on the opening 15b in the liquid crystal layer 30 of
Since it does not contribute to display, the display quality is reduced. For example, in a normally black display mode, the effective aperture ratio decreases and the display luminance decreases.

As described above, in the liquid crystal display device 300, the direction in which the orientation of the liquid crystal molecules 30a changes is uniquely determined by the oblique electric field formed by the picture element electrode 15B having the opening 15b. Although the display roughness that can occur in the typical liquid crystal display device 200 can be prevented, the brightness is reduced. Since the liquid crystal display device 100 of the present embodiment includes the upper conductive layer 14 having the opening 14a and the lower electrode 12 provided to face the opening 14a,
An electric field can be applied to almost the entire region of the liquid crystal layer 30 located on the opening 14a to contribute to display. Therefore, the liquid crystal display device 100 of the present embodiment has high brightness,
A high-quality display without roughness can be realized.

The shape of the opening 14a of the upper conductive layer 14 of the two-layer structure electrode (picture element electrode) 15 included in the liquid crystal display device of the present embodiment (shape viewed from the normal direction of the substrate) will be described. The shape of the opening 14a may be polygonal,
It may be circular or oval.

The display characteristics of the liquid crystal display device show azimuth dependence depending on the alignment state (optical anisotropy) of liquid crystal molecules. In order to reduce the azimuth angle dependency of the display characteristics, it is preferable that the liquid crystal molecules are aligned with equal probability for all azimuth angles. Further, it is more preferable that the liquid crystal molecules in each picture element region are aligned with equal probability for all azimuth angles. Therefore, the shape of the opening 14a is
It is preferable that the liquid crystal molecules in each of the picture element regions have a shape such that they are aligned with equal probability at all azimuth angles. Specifically, the shape of the opening 14a preferably has rotational symmetry with the center (normal direction) of the picture element region as the axis of symmetry. It is more preferred to have an axis of high rotational symmetry of two or more rotation axes.

The orientation of the liquid crystal molecules 30a when the shape of the opening 14a is polygonal will be described with reference to FIGS. 6 (a) to 6 (c). FIGS. 6A to 6C respectively show
FIG. 3 schematically shows an alignment state of the liquid crystal molecules 30a as viewed from a normal direction of the substrate. In FIGS. 6B and 6C, which show the alignment state of the liquid crystal molecules 30a as viewed from the normal direction of the substrate, the ends of the liquid crystal molecules 30a drawn in an elliptical shape are indicated by black dots. This indicates that the liquid crystal molecules 30a are inclined such that the end is closer to the substrate side where the two-layer electrode having the opening 14a is provided than the other end. The same applies to the following drawings.

Here, a rectangle (including a square and a rectangle)
A structure in which a rectangular opening 14a is formed corresponding to the picture element region will be described as an example. 1A in FIGS. 6A to 6C
The cross sections along the line -1A 'correspond to FIGS. 1A to 1C, respectively, and will be described with reference to FIGS. 1A to 1C. Of course, the picture element area (picture element electrode 15)
Is not limited to this.

When the pixel electrode 15 having the lower conductive layer 12 and the upper conductive layer 14 and the counter electrode 22 are at the same potential, that is, when no voltage is applied to the liquid crystal layer 30, the TFT substrate 100a and the counter substrate The liquid crystal molecules 30a whose alignment direction is regulated by a vertical alignment layer (not shown) provided on the surface of the liquid crystal layer 30 on the liquid crystal layer 30 side in FIG.
As shown in (a), a vertical alignment state is taken.

When an electric field is applied to the liquid crystal layer 30 to generate an electric field represented by the equipotential line EQ shown in FIG. 1A, the liquid crystal molecules 30a having a negative dielectric anisotropy have an axial azimuth. Generates a torque that is parallel to the equipotential line EQ. FIG.
As described with reference to (a) and (b), the liquid crystal molecules 30a under an electric field represented by an equipotential line EQ perpendicular to the molecular axis of the liquid crystal molecules 30a have tilted (rotated) liquid crystal molecules 30a. ) Is not uniquely determined (see FIG. 5).
(A)) While the change in the orientation (tilt or rotation) does not easily occur, the liquid crystal molecule 30a placed under the equipotential line EQ inclined with respect to the molecular axis of the liquid crystal molecule 30a is tilted (rotated). ) Since the direction is uniquely determined, the change in orientation easily occurs. In the structure shown in FIG. 6, the upper conductive layer 14 in which the molecular axis of the liquid crystal molecule 30a is inclined with respect to the equipotential line EQ.
Of the liquid crystal molecules 3 from the four edges of the rectangular opening 14a of FIG.
0a begins to tilt. Then, as described with reference to FIG. 5C, the surrounding liquid crystal molecules 30a are also inclined so as to match the orientation of the inclined liquid crystal molecules 30a at the edges of the openings 14a. As shown in ()), the axial orientation of the liquid crystal molecules 30a is stabilized in the state (radial tilt alignment).

As described above, the opening 14 of the upper conductive layer 14 is formed.
If a is not a slit shape (a shape in which the width (the direction perpendicular to the length) is extremely narrow with respect to the length) but a rectangular shape, the liquid crystal molecules 30a in the picture element region will not be opened when the voltage is applied. 1
Since the liquid crystal molecules 30a are inclined from the edges of the four sides 4a toward the center of the opening 14a, the liquid crystal molecules 30a near the center of the opening 14a where the alignment control force of the liquid crystal molecules 30a from the edges is balanced. Liquid crystal molecules 30a around the opening 14
A state is obtained in which the liquid crystal molecules 30a are continuously tilted radially around the liquid crystal molecules 30a near the center of a. As described above, when the liquid crystal molecules 30a take a radially inclined alignment for each picture element region, the liquid crystal molecules 30a are oriented in all viewing directions (including azimuthal directions).
The existence probabilities of the liquid crystal molecules 30a in the respective axis directions become substantially equal, and a high-quality display without roughness can be realized in all viewing angle directions.

Further, when the shape of the opening 14a is a square having a high rotational symmetry (having a four-time rotation axis), the center of the opening 14a is more apt than a rectangle having a low rotational symmetry (having a two-time rotation axis). Since the symmetry of the radially inclined alignment of the liquid crystal molecules 30a to be described is increased, it is possible to realize a favorable display with less roughness in the viewing angle direction. The opening 14a
Is exemplified as a rectangular shape, but other polygons may be used as long as the liquid crystal molecules 30a inside the opening 14a have a stable radially inclined orientation when a voltage is applied, and a regular polygon having high rotational symmetry may be used. Is more preferred.

The radially tilted alignment of the liquid crystal molecules 30a is more counterclockwise or counterclockwise as shown in FIGS. 8B and 8C than the simple radially tilted alignment as shown in FIG. The clockwise spiral radially inclined orientation is more stable. In the spiral alignment, the alignment direction of the liquid crystal molecules 30a does not change spirally along the thickness direction of the liquid crystal layer 30 as in a normal twist alignment, but the alignment direction of the liquid crystal molecules 30a is viewed in a minute region. And almost no change along the thickness direction of the liquid crystal layer 30. That is, the liquid crystal layer 30
8 (b) or 8 (c) in the cross section at any position in the thickness direction (cross section in a plane parallel to the layer plane), and along the thickness direction of the liquid crystal layer 30. Almost no twist deformation. However, a certain amount of twist deformation occurs in the entire opening 14a.

When a material obtained by adding a chiral agent to a nematic liquid crystal material having a negative dielectric anisotropy is used, FIG.
As shown in (b) and (b), when a voltage is applied, the liquid crystal molecules 30a assume a counterclockwise or clockwise spiral radially inclined orientation around the opening 14a. Whether clockwise or counterclockwise depends on the type of chiral agent used. Therefore,
The liquid crystal layer 30 in the opening 14a is spirally and radially inclined when a voltage is applied, so that the direction of the liquid crystal molecules 30a that are radially inclined and that are wound around the liquid crystal molecules 30a that stand perpendicular to the substrate surface can be changed. Since it can be made constant in all the openings 14a, uniform display without roughness can be achieved. Further, since the direction in which the liquid crystal molecules 30a standing perpendicular to the substrate surface are wound around the liquid crystal molecules 30a, the response speed when a voltage is applied to the liquid crystal layer 30 is improved.

The shape of the opening 14a is not limited to the polygon described above, but may be a circle or an ellipse.

The alignment state of the liquid crystal molecules 30a when the shape of the opening 14a is circular will be described with reference to FIGS. 9 (a) to 9 (c). FIGS. 9A to 9C schematically show the alignment states of the liquid crystal molecules 30a viewed from the normal direction of the substrate. Here, a structure in which a circular opening 14a is formed in a rectangular picture element region will be described as an example. 9 (a) to 9 (c) correspond to FIGS. 1 (a) to 1 (c), respectively.
This will be described with reference to FIGS. 1 (a) to 1 (c).

When the pixel electrode 15 having the lower conductive layer 12 and the upper conductive layer 14 and the counter electrode 22 are at the same potential, that is, when no voltage is applied to the liquid crystal layer 30, the TFT substrate 100a and the counter substrate The liquid crystal molecules 30a whose alignment direction is regulated by a vertical alignment layer (not shown) provided on the surface of the liquid crystal layer 100b on the side of the liquid crystal layer 30 are shown in FIG.
As shown in (a), a vertical alignment state is taken.

When an electric field is applied to the liquid crystal layer 30 to generate an electric field represented by the equipotential line EQ shown in FIG. 1A, the liquid crystal molecules 30a having a negative dielectric anisotropy have an axial azimuth. Generates a torque that is parallel to the equipotential line EQ. FIG.
As described with reference to (a) and (b), the liquid crystal molecules 30a under an electric field represented by an equipotential line EQ perpendicular to the molecular axis of the liquid crystal molecules 30a have tilted (rotated) liquid crystal molecules 30a. ) Is not uniquely determined (see FIG. 5).
(A)) While the change in the orientation (tilt or rotation) does not easily occur, the liquid crystal molecule 30a placed under the equipotential line EQ inclined with respect to the molecular axis of the liquid crystal molecule 30a is tilted (rotated). ) Since the direction is uniquely determined, the change in orientation easily occurs. In the structure shown in FIG. 9, the upper conductive layer 14 in which the molecular axis of the liquid crystal molecule 30a is inclined with respect to the equipotential line EQ.
Liquid crystal molecules 3 from the peripheral edge of the circular opening 14a of FIG.
0a begins to tilt. Then, as described with reference to FIG. 5C, the surrounding liquid crystal molecules 30a are also tilted so as to match the alignment of the tilted liquid crystal molecules 30a at the edges of the openings 14a. As shown in ()), the axial orientation of the liquid crystal molecules 30a is stabilized in the state (radial tilt alignment).

As described above, the opening 14 of the upper conductive layer 14 is formed.
If a is circular, the liquid crystal molecules 30a in the picture element region
Since the liquid crystal molecules 30a incline from the peripheral edge of the opening 14a toward the center of the opening 14a when a voltage is applied, the center of the opening 14a where the alignment regulating force of the liquid crystal molecules 30a from the edge balances. The liquid crystal molecules 30a in the vicinity maintain the state of being vertically aligned with respect to the substrate surface, and the liquid crystal molecules 30a around the liquid crystal molecules 30a close to the center of the opening 14a.
A state in which the liquid crystal molecules 30a are continuously tilted radially around 0a (radially tilted alignment) is obtained. When the shape of the opening 14a is circular, the center of the radially inclined alignment (the position of the liquid crystal molecules 30a aligned perpendicular to the substrate surface) is more stably formed at the center of the opening 14a than in the case of the square.
High-quality display without roughness can be realized in all directions when a voltage is applied.

The effect of stabilizing the center position of the radially inclined orientation, which is obtained when the shape of the opening 14a is circular, is not only because the rotation symmetry of the circle is high, but also because the liquid crystal molecules 30a
It is considered that the edge of the opening 14a that determines the direction in which the tilt is inclined is continuous. The effect of stabilizing the radially inclined orientation due to the continuous edges of the opening 14a can be obtained even when the shape of the opening 14a is an ellipse (an ellipse).

The radially inclined alignment of the liquid crystal molecules 30a is further stabilized by imparting a spiral alignment as described above with reference to FIG. Therefore,
As shown in FIGS. 10 (a) and 10 (b), it is more preferable to form a spiral or clockwise spiral oblique orientation around the opening 14a. In particular, the opening 14
When the area of “a” increases and the distance from the side to the center of the opening 14a increases, the alignment of the liquid crystal molecules 30a located in the opening 14a becomes difficult to stabilize. . For example, by adding a chiral agent to a liquid crystal material, a spiral alignment can be imparted to the radial alignment.

In the above description, the configuration and operation of a two-layer structure electrode having an opening have been described by exemplifying a configuration having one opening for each picture element region. However, a plurality of openings are provided for each picture element region. May be. Hereinafter, a configuration using a pixel electrode having a two-layer structure having a plurality of openings for each pixel region will be described.

In the case where a plurality of openings are provided for each picture element region, each of the plurality of openings is rotated as described above so that the liquid crystal molecules in the picture element region are uniformly oriented in all directions. It is preferable to have a shape having symmetry, and it is preferable that the arrangement of the plurality of openings has rotational symmetry. Hereinafter, the configuration and operation of a liquid crystal display device having a two-layered picture element electrode 15 in which a plurality of openings are arranged in each picture element area so as to have rotational symmetry will be described.

FIG. 11 shows a plurality of openings 14a (14a1).
And 14a2), and each of the openings 14
A concave portion 13r is formed in the dielectric value layer 13 in a.
The cross-sectional structure of one pixel region of the liquid crystal display device 400 including the pixel electrode 15 is schematically shown.

FIG. 11A schematically shows the alignment state (OFF state) of the liquid crystal molecules 30a in the liquid crystal layer 30 to which no voltage is applied. FIG. 11B shows the liquid crystal layer 3.
A state where the orientation of the liquid crystal molecules 30a starts to change in accordance with the voltage applied to 0 (ON initial state) is schematically shown. FIG. 11C schematically shows a state in which the orientation of the liquid crystal molecules 30a changed according to the applied voltage has reached a steady state. FIGS. 11 (a), (b) and (c)
A pixel electrode 15 having one opening 14a for each pixel region
FIG. 1A for a liquid crystal display device 100 including
(B) and (c) respectively. Note that FIG.
Thus, lower conductive layer 12 provided so as to face openings 14a1 and 14a2 via dielectric layer 13 overlaps each of openings 14a1 and 14a2, and has a region between openings 14a1 and 14a2. Although the example in which the lower conductive layer 12 is formed so as to exist also in the (region where the upper conductive layer 14 is present) is shown, the arrangement of the lower conductive layer 12 is not limited to this, and the openings 14a1 and 14a2 are respectively arranged as shown in FIG. 2 (a) and 2 (b). Further, the lower conductive layer 12 formed at a position opposite to the region where the conductive layer of the upper conductive layer 14 is present via the dielectric layer 13 does not substantially affect the electric field applied to the liquid crystal layer 30. It is not particularly necessary to perform patterning, but patterning may be performed.

As shown in FIG. 11A, the picture element electrode 1
5 and the counter electrode 22 are at the same potential (when no voltage is applied to the liquid crystal layer 30), the liquid crystal molecules 3
0a is oriented perpendicular to the surfaces of both substrates 11 and 21.

When a voltage is applied to the liquid crystal layer 30, FIG.
A potential gradient represented by the equipotential line EQ shown in FIG. Upper conductive layer 14 of pixel electrode 15 and counter electrode 22
A uniform potential gradient represented by equipotential lines EQ parallel to the surfaces of the upper conductive layer 14 and the counter electrode 22 is formed in the liquid crystal layer 30 located between the upper and lower conductive layers 14 and 22. Upper conductive layer 1
In the liquid crystal layer 30 located above the four openings 14a1 and 14a2, a potential gradient corresponding to the potential difference between the lower conductive layer 12 and the counter electrode 22 is formed. At this time, the liquid crystal layer 30
Since the potential gradient formed in the liquid crystal layer 30 is affected by the voltage drop due to the dielectric layer 13, the equipotential lines EQ formed in the liquid crystal layer 30 fall in the regions corresponding to the openings 14a1 and 14a2 (equipotential). A plurality of "valleys" are formed in the line EQ). Openings 14a1 and 1a through dielectric layer 13
Since lower conductive layer 12 is formed in a region facing 4a2, upper conductive layer 14 is also provided in liquid crystal layer 30 located near the center of each of openings 14a1 and 14a2.
In addition, a potential gradient represented by an equipotential line EQ parallel to the surface of the counter electrode 22 is formed (“bottom of the valley” of the equipotential line EQ). An oblique electric field represented by an inclined equipotential line EQ is formed in the liquid crystal layer 30 on the edges of the openings 14a1 and 14a2 (the periphery of the opening including the boundaries (extensions) of the openings) EG. .

A torque acts on the liquid crystal molecules 30a having negative dielectric anisotropy so as to orient the axis of the liquid crystal molecules 30a in parallel to the equipotential line EQ. Therefore, the liquid crystal molecules 30a on the edge portion EG are clockwise in the right edge portion EG in the drawing and counterclockwise in the left edge portion EG in the drawing, as indicated by arrows in FIG. 11B. In the directions, they incline (rotate), and are oriented parallel to the equipotential lines EQ.

As shown in FIG. 11B, the openings 14a1 and 14a2 of the liquid crystal display device 400 according to the present invention.
Electric field (oblique electric field) represented by equipotential lines EQ inclined with respect to the axis direction of the liquid crystal molecules 30a at the edge portion EG of
When liquid crystal molecules 3 are generated, as shown in FIG.
0a is inclined in a direction in which the amount of inclination for becoming parallel to the equipotential line EQ is small (counterclockwise in the illustrated example). Also,
Equipotential line E perpendicular to the axial direction of the liquid crystal molecules 30a
Liquid crystal molecules 3 located in a region where an electric field represented by Q is generated
As shown in FIG. 5C, 0a is set on the inclined equipotential line EQ so that the alignment is continuous with (aligned with) the liquid crystal molecules 30a located on the inclined equipotential line EQ. It tilts in the same direction as the liquid crystal molecules 30a located.

As described above, the change in the alignment starting from the liquid crystal molecules 30a positioned on the inclined equipotential line EQ progresses, and when the liquid crystal molecules reach a steady state, as shown in FIG. A symmetric inclined orientation (radial inclined orientation) is formed with respect to the center SA of each of the portions 14a1 and 14a2. Further, the liquid crystal molecules 30a on the region of the upper conductive layer 14 located between the two adjacent openings 14a1 and 14a2 are also aligned so as to be continuous with the liquid crystal molecules 30a at the edges of the openings 14a1 and 14a2. Obliquely oriented (to match). Openings 14a1 and 1
Liquid crystal molecules 30 on the portion located at the center of the edge of 4a2
Since a is affected by the liquid crystal molecules 30a at the respective edge portions to the same extent, the liquid crystal molecules 30a maintain the vertical alignment state similarly to the liquid crystal molecules 30a located at the center of the openings 14a1 and 14a2. As a result, two adjacent openings 14a1
Between 14a2 and 14a2, the liquid crystal layer on the upper conductive layer 14 is also in a radially inclined alignment state. However, the openings 14a1 and 14a
a2 and the radially inclined alignment of the liquid crystal layer and the openings 14a1 and 14a1
The tilt direction of the liquid crystal molecules is different from the radial tilt direction of the liquid crystal layer between 4a2. Paying attention to the alignment near the liquid crystal molecules 30a located at the center of each of the radially inclined alignment regions shown in FIG. 11C, a cone spreading toward the counter electrode is formed in the openings 14a1 and b14a2. While the liquid crystal molecules 30a are inclined to form, the liquid crystal molecules 30 are inclined between the openings so as to form a cone extending toward the upper conductive layer 14. In each of the radially inclined alignments, the liquid crystal molecules 30 at the edge portions are used.
a is formed so as to match the tilt orientation of a.
The two radial tilt orientations are continuous with each other.

As described above, when a voltage is applied to the liquid crystal layer 30, a plurality of openings 14a1 provided in the upper conductive layer 14 are formed.
Liquid crystal molecules 3 on the edge EG of each of
0a, then the liquid crystal molecules 30a in the peripheral region
Are tilted so as to match the tilted alignment of the liquid crystal molecules 30a on the edge portion EG, thereby forming a radial tilted alignment. Therefore, the larger the number of openings 14a formed in one pixel region, the larger the number of liquid crystal molecules 30a that first start to tilt in response to an electric field. The time required for the formation is reduced. That is, the response speed of the liquid crystal display device can be improved by increasing the number of openings 14a formed in the pixel electrode for each pixel region.

As described above, a plurality of openings 1 are provided for each picture element region.
By forming 4a1 and 14a2, a liquid crystal display device having excellent display quality in all directions is realized, and the response characteristics of the liquid crystal display device are also improved.

Next, with reference to FIGS. 12 and 13, the relationship between the shape and relative arrangement of the plurality of openings 14a and the orientation of the liquid crystal molecules 30a will be described. FIG.
11 and 13 are sectional views taken along lines 1C-1C 'and 1D-1D' of FIG.

FIGS. 12 and 13 show a rectangular picture element electrode 1.
5 (picture element region) is illustrated, but the external shape of the picture element electrode 15 (upper conductive layer 14) is not limited to this. Also,
The liquid crystal display device according to the present invention is not limited to the one having one electrode configuration shown in FIGS. 12 and 13 for one picture element region, and the electrode configuration shown in FIGS. You may have two or more inside. Further, there is no particular limitation on the relative positional relationship between the outer periphery of the pixel electrode 15 (upper conductive layer 14) and the opening 14a, and a part of the plurality of openings 14 defines the outer periphery of the upper conductive layer 14. Alternatively, they may be formed so as to overlap corners. This is the same for the liquid crystal display devices of other embodiments showing the picture element region having the plurality of openings 14a. The relative arrangement between the openings 14a, which is preferable for stabilizing the alignment of the liquid crystal molecules over the entire picture element region (and improving the response speed), will be described later.

First, the shape of each opening 14a is
As explained above, it may be polygonal, circular or oval. In order to improve the viewing angle characteristics in all the azimuthal directions of the liquid crystal display device 400 (eliminate the roughness of the display), it is preferable that each shape of the opening 14a has high rotational symmetry. A regular polygon such as a square or a circle shown in FIG. 13 is preferable. Since the relationship between the shape of each opening 14a and the alignment state of the liquid crystal molecules 30a is as described above, the description is omitted here.

In the configuration in which the plurality of openings 14a are formed, it is preferable that the relative arrangement of the plurality of openings 14a has rotational symmetry. For example, as shown in FIG. 12, when four square openings 14a are formed in the upper conductive layer 14 of the square (that is, when the pixel region is a square), the four openings 14a are The upper conductive layer 14 is preferably arranged to have rotational symmetry about the center SA. As shown in the figure, it is preferable to arrange the square upper conductive layer 14 such that the center SA is the rotation axis four times. With this arrangement, as shown in FIGS. 12B and 12C, when a voltage is applied to the liquid crystal layer 30, the regions having the radially inclined alignment formed around the respective openings 14a become: Center S of upper conductive layer 14
It has four-fold rotational symmetry about A. As a result, the viewing angle characteristics of the liquid crystal display device 400 are further uniformed in all azimuthal directions.

FIG. 12 shows an example in which four openings 14a are formed in one picture element region.
The number of a is not limited to this. The number of the openings 14a formed in one picture element region is determined in consideration of the size and shape of the picture element region, the size of the region where the radially inclined orientation is stably formed by one opening 14a, and the response speed. It is set appropriately. When a large number of openings 14a are formed in one picture element region, in order to improve the uniformity of the viewing angle characteristics, the openings 14a are arranged so as to have rotational symmetry throughout the picture element region. However, depending on the shape of the picture element area, it may not be possible to arrange the picture element area so as to have rotational symmetry over the entire picture element area. It is preferable to arrange them so as to have rotational symmetry over as large an area as possible. For example, when the picture element region is a rectangle, the rectangle is divided into a plurality of squares, and a plurality of openings 14a are formed so as to have rotational symmetry with respect to each square, so that a sufficiently uniform viewing angle characteristic is obtained. Can be obtained.

FIG. 13 shows a configuration in which a circular opening 14a is provided instead of the square opening 14a shown in FIG.

As described above with reference to FIG. 12, by arranging the four openings 14a so that the center SA of the upper conductive layer 14 becomes the rotation axis four times, the viewing angle characteristics of the liquid crystal display device can be improved. Further improvements can be made. In addition, a circular shape of the opening 14a is more preferable than a polygonal shape.
Liquid crystal molecules 3 along the edge of each opening 14a
Since the continuity of the alignment of Oa is high, the radially inclined alignment of the liquid crystal molecules 30a is more stable. Further, the plurality of openings 14
In the configuration where a is provided, when the shape of the opening 14a is circular, the continuity between the radially inclined orientations formed by the adjacent openings 14a is high, and a plurality of radially inclined orientations formed in the pixel region are formed. The advantage of easy stability is obtained.

For example, as shown in FIG. 14, even in a configuration in which four circular openings 14a are arranged so that their centers are located at the corners of a rectangle, the liquid crystal molecules located on the diagonal of the rectangle are arranged. 30a can form a continuous tilted orientation. On the other hand, if the four openings 14a in FIG. 14 are square, the rectangular diagonal formed by connecting the centers of the openings 14a does not coincide with the square diagonal of the opening 14a. ,
The orientation of the liquid crystal molecules 30a in the region surrounded by the four openings 14a is unlikely to be continuous. On the other hand, if the shape of the four openings 14a is a rectangle having a similar relationship to the rectangle formed by the centers of the four openings 14a, the above-mentioned problem can be solved, but the four openings 14a are formed in the respective openings 14a. The continuity of the radially inclined orientation is reduced. Therefore, it is preferable to appropriately set the shape and arrangement of the opening 14a in consideration of the shape and size of the picture element region.

The configuration of the liquid crystal display device of this embodiment can employ the same configuration as that of a known vertical alignment type liquid crystal display device, except that the picture element electrode 15 is a two-layered electrode having an opening. Can be manufactured by a known manufacturing method.

Up to the step of depositing a transparent conductive layer (typically, an ITO layer) to be the lower conductive layer 12, it can be carried out by a known manufacturing method. This conductive layer is patterned into a predetermined shape in the process of a conventional liquid crystal display device to form a pixel electrode. In the patterning step of the picture element electrode in the manufacturing process of the conventional liquid crystal display device, the lower conductive layer 12 of the liquid crystal display device of the present embodiment can be patterned. The pattern of the lower conductive layer may be the same as the picture element electrode, or may be a divided pattern corresponding to the opening 14a formed in the upper conductive layer 14. The lower conductive layer 12 is electrically connected to a drain or the like of the TFT similarly to a conventional picture element electrode.

The dielectric layer 13 is formed over substantially the entire surface of the substrate on which the lower conductive layer 12 has been patterned. A conductive layer is deposited on the dielectric layer 13 again. By patterning the obtained conductive layer, an upper conductive layer 14 having an opening 14a is formed. A method of forming the recess 13r in the dielectric layer 13 in a region corresponding to the opening 14a of the upper conductive layer 14 will be described later in detail.

A contact hole for connecting the upper conductive layer 14 to the drain electrode of the TFT is formed in the dielectric layer 13.
In advance. This step can also be performed by a known process. When the configuration in which the upper conductive layer 14 and the lower conductive layer 12 are driven at the same potential is employed, the upper conductive layer 14 and the lower conductive layer 12 may be connected to the same TFT as illustrated. Further, when this configuration is employed, there is an advantage that a conventional driving circuit can be used as it is.

Typically, in order to vertically align liquid crystal molecules having negative dielectric anisotropy, a vertical alignment layer (not shown) is provided on the surface of the pixel electrode 15 and the counter electrode 22 on the liquid crystal layer 30 side. Are formed. The vertical alignment layer is composed of the dielectric layer 13
After the openings 13a and the upper conductive layer 14 are formed, they are formed by printing in the display area of the substrate.

As the liquid crystal material, a nematic liquid crystal material having negative dielectric anisotropy is used. A guest-host mode liquid crystal display device can also be obtained by adding a dichroic dye to a nematic liquid crystal material having negative dielectric anisotropy. The guest-host mode liquid crystal display device does not require a polarizing plate.

Hereinafter, a specific structure of the liquid crystal display device according to the present invention will be exemplified, and in particular, a structure of the dielectric layer 13 having the concave portion 13r and a preferable forming method thereof will be described.

(Embodiment 1) FIG. 15 shows a planar structure of a transmission type liquid crystal display device 500 of Embodiment 1, and FIG.
FIG. 16 shows a cross-sectional view taken along line A ′.

The liquid crystal display device 500 includes a TFT substrate 500
a, a counter substrate 500b, and a vertically aligned liquid crystal layer 30 disposed therebetween. Each of the pixel regions arranged in a matrix is driven by a voltage applied to the pixel electrode 15 and the counter electrode 22. The pixel electrode 15 is connected to a source line 43 to which a signal voltage is applied by a TFT.
The switching of the TFT 44 is controlled by a scanning signal given from the gate wiring 41. TF turned ON by scanning signal
A signal voltage is applied to the picture element electrode 15 connected to T44.

The pixel electrode 15 is composed of a lower conductive layer 12, an upper conductive layer 14, and a dielectric layer (first
A dielectric layer 13a and a second dielectric layer (for example, a photosensitive resin layer) 13b). Lower conductive layer 12 and upper conductive layer 14 are electrically connected to each other at contact hole 45. The upper conductive layer 14 has an opening 14
a, and generates an oblique electric field at the edge when a voltage is applied. Four openings 14 a are formed in a region surrounded by the gate wiring 41, the source wiring 43, and the auxiliary capacitance wiring 42. Eight openings 14a are formed for each picture element region.

The auxiliary capacitance line 42 is formed so as to extend substantially in the vicinity of the center of the picture element region in parallel with the gate line 41. The auxiliary capacitance line 42 forms an auxiliary capacitance with the lower conductive layer 12 opposed via the gate insulating layer 46. The auxiliary capacitance is provided to improve the retention rate of the pixel capacitance. Of course, the auxiliary capacitance may be omitted, and the structure of the auxiliary capacitance is not limited to the above example.

In the liquid crystal display device 500, the dielectric layer 13 provided on the lower conductive layer 12 is formed of a first dielectric layer 13a and a second dielectric layer 13b. Opening 14 of first dielectric layer (also referred to as “protective layer”) 13 a that is patterned into upper conductive layer 14 to be formed later
An opening 13a 'having a shape similar to that of the opening 14a is formed in a region opposed to a. This first dielectric layer 13a
The second dielectric layer 13b is formed thereon by, for example, applying a photosensitive resin. In the process of forming the second dielectric layer 13b on the first dielectric layer 13a having the opening 13a ', the first opening 13 of the first dielectric layer 13a is formed.
Since the material (for example, photosensitive resin) of the second dielectric layer 13b falls into a ′, a recess 13r is formed in a self-alignment with the first opening 13a ′. The method of applying the photosensitive resin material on the first dielectric layer 13a is not limited to the coating method, and for example, a printing method may be used. Considering that a contact hole is formed in the second dielectric layer, the process can be simplified, and thus it is preferable to use a photosensitive resin, but the present invention is not limited to this. Further, an inorganic insulating material such as SiOx or SiNx may be deposited using a thin film deposition method. There is no particular limitation on the material and the application method as long as an insulating material can be applied so as to reflect a surface step (a difference in surface height) due to the first opening 13a 'formed in the first dielectric layer 13a.

The depth of the recess 13r is determined by the first dielectric layer 13a.
, The viscosity of the photosensitive resin to be the second dielectric layer 13b, application conditions, and the like.
Therefore, by adjusting the amount of light when exposing the photosensitive resin layer, compared to a method of adjusting the depth of the recess 13r,
Excellent productivity and reproducibility.

In the liquid crystal display device 500 shown in FIG.
By the opening 13a 'provided in the first dielectric layer 13a,
The recess 13r of the second dielectric layer 13b was formed.
As shown in a liquid crystal display device 500 ′ shown in FIG.
The upper conductive layer 14 is formed on the gate insulating film 46 provided below.
The opening 46a may be formed in a region corresponding to the opening 14a. The lower conductive layer 12 is formed, for example, so as to cover at least the opening 46a of the gate insulating film 46 as illustrated. An opening 46a is also formed in the gate insulating film 46.
Is formed, the concave portion 13r can be deepened without increasing the thickness of the first dielectric layer 13a.

Further, the liquid crystal display device 50 shown in FIG.
0 '', the first dielectric layer 13a is
It may be formed below. With such a configuration,
The opening 46a of the gate insulating layer 46 and the first opening 13a 'of the first dielectric layer 13 can be formed at one time by a single photolithography process, thereby improving production efficiency. Of course, the gate insulating layer 46 and the first dielectric layer 13
It is preferable to select a material so that the etching process can be performed using the same etchant.

Next, the aforementioned liquid crystal display devices 500 and 50
The manufacturing method of 0 ′ and 500 ″ will be described.

FIGS. 19A to 19E show the liquid crystal display device 5.
It is sectional drawing which shows typically the manufacturing process of the TFT substrate 500a of No. 00.

As shown in FIG. 19A, an insulating layer (not shown) made of Ta ₂ O ₅ , SiO ₂ or the like as a base coat film, if necessary, on an insulating transparent substrate (eg, a glass substrate) 11. To form Then, a gate electrode 48 (including the gate signal line 41) is formed by forming a metal layer made of A1, Mo, Ta, or the like by a sputtering method and patterning the same. Here, the gate electrode 48 is formed using Ta. At this time, the auxiliary capacitance signal line 42
Are formed in the same step using the same material. Next, a gate insulating layer 46 is formed on almost the entire surface of the substrate 11 so as to cover the gate electrode 48. Here, the thickness is about 300n
A mN SiNx film is deposited by a P-CVD method to form a gate insulating layer 46. Note that the gate electrode 48 can be anodized and the gate anodic oxide film 49 can be used as a gate insulating layer. Of course, a two-layer structure including an anodic oxide film and an insulating layer such as SiNx may be used.

On the gate insulating layer 46, a Si layer serving as the channel layer 50 and the electrode contact layer 51 is continuously formed by CV.
Deposit by D method. The channel layer 50 has a thickness of about 150 n
m of the amorphous silicon layer, and the electrode contact layer 51
Use an amorphous Si or microcrystalline Si layer with a thickness of about 50 nm doped with an impurity such as phosphorus. The channel layer 50 and the electrode contact layer 51 are formed by patterning these Si layers by a dry etching method using a mixed gas of HCl + SF _{6 or} the like.

Thereafter, as shown in FIG. 19B, a transparent conductive film (ITO) constituting the lower conductive layer 12 is deposited to a thickness of about 150 nm by a sputtering method. Then, A1,
A metal film made of Mo, Ta, or the like is laminated. here,
Ta is used. By patterning these metal layers, a source signal line 43, a source electrode 52, and a drain electrode 53 are formed. Next, the transparent conductive film is patterned to form the lower conductive layer 12. Then, the channel portion of the thin film transistor (TFT) is formed by patterning the electrode contact layer 51 by a dry etching method.

Next, as shown in FIG.
After depositing an insulating film made of x or the like by about 600 nm by a CVD method, the first dielectric layer (protective layer) 13a is formed by patterning. During patterning, a first opening 13a 'is formed at a position facing the opening 14a to be formed in a later step. Further, a contact hole 45 for electrically connecting the lower conductive layer 12 and the upper conductive layer 14 is also formed on the auxiliary capacitance wiring 42 at the same time.

Next, as shown in FIG. 19D, a photosensitive resin to be the second dielectric layer 13b is applied on the first dielectric layer 13a. At this time, the first opening 1
When the photosensitive resin falls (flows) into 3a ', a second dielectric layer 13b in which a recess 13r is formed in a self-aligned manner with respect to the opening 13a is obtained. By exposing and developing the photosensitive resin of the second dielectric layer 13b, a contact hole 45 for electrically connecting the lower conductive layer 12 and the upper conductive layer 14 is formed. The photosensitive resin layer is formed to a thickness of about 1.5 μm using, for example, a positive photosensitive resin (acrylic resin manufactured by JSR: a relative dielectric constant of 3.7). At this time, the depth of the recess 13r can be adjusted by adjusting the viscosity of the photosensitive resin and the application conditions. In addition, using a non-photosensitive resin, in a photolithography process using a separate photoresist,
The second dielectric layer 13b may be formed.

Next, as shown in FIG. 19E, a transparent conductive film (ITO) constituting the upper conductive layer 14 is laminated on the second dielectric layer 13b to a thickness of about 100 nm by a sputtering method. . Thereafter, the transparent conductive film is patterned according to a conventional method to form the upper conductive layer 14 having the opening 14a.

In this manner, a two-layered pixel electrode composed of the lower conductive layer 12 made of the ITO layer, the upper conductive layer 14 made of the ITO layer, and the dielectric layer 13 interposed therebetween is formed. The TFT substrate 500a provided is obtained.

Here, the upper conductive layer 14 and the lower conductive layer 1
The dielectric layer 13 sandwiched between the two layers is formed of two layers, the first dielectric layer 13a and the second dielectric layer 13b, but this is not necessary and may include another layer. Dielectric layer 1
There is no limitation on the type of material or the number of layers forming 3. It is preferable to use a highly transparent material so that the light use efficiency does not decrease. Further, when the second dielectric layer 13b is formed using a photosensitive resin, there is obtained an advantage that the step of forming the contact hole 45 can be simplified. First opening 13
The thickness of the first dielectric layer 13a having a ′ depends on the viscosity of the material forming the second dielectric layer and the application conditions,
Since it affects the depth of r, it can be adjusted to obtain a predetermined depth.

On the other hand, as the counter substrate 500b, the counter electrode 22 made of ITO is formed on the color filter substrate 21 by using, for example, a sputtering method. Then, finally, the liquid crystal display device 500 is obtained through a process of forming a vertical alignment film, a process of bonding to a counter substrate, and a process of injecting a nematic liquid crystal material having negative dielectric anisotropy. These steps are performed by a known method.

Next, the liquid crystal display device 50 shown in FIG.
The method of manufacturing 0 'will be described. Since the configuration other than the TFT substrate 500a 'is the same as that of the liquid crystal display device 500 shown in FIG. 16, the description of the manufacturing method is omitted here.

FIGS. 20A to 20E show the liquid crystal display device 5.
It is sectional drawing which shows typically the manufacturing process of 00 'of the TFT substrate 500a'.

As shown in FIG. 20A, an insulating layer (not shown) made of Ta ₂ O ₅ , SiO _2, or the like as a base coat film, if necessary, on an insulating transparent substrate (eg, a glass substrate) 11. To form Then, a gate electrode 48 (including the gate signal line 41) is formed by forming a metal layer made of A1, Mo, Ta, or the like by a sputtering method and patterning the same. Here, the gate electrode 48 is formed using Ta. At this time, the auxiliary capacitance signal line 42
Are formed in the same step using the same material. Next, a gate insulating layer 46 is formed on almost the entire surface of the substrate 11 so as to cover the gate electrode 48. Here, the thickness is about 300n
A mN SiNx film is deposited by a P-CVD method to form a gate insulating layer 46. When patterning the gate insulating layer 46, an opening 46a is formed at a position facing the opening 14a. Note that the gate electrode 48 can be anodized and the gate anodic oxide film 49 can be used as a gate insulating layer. Of course, a two-layer structure including an anodic oxide film and an insulating layer such as SiNx may be used.

On the gate insulating layer 46, a Si layer serving as the channel layer 50 and the electrode contact layer 51 is continuously formed by CV.
Deposit by D method. The channel layer 50 has a thickness of about 150 n
m of the amorphous silicon layer, and the electrode contact layer 51
Use an amorphous Si or microcrystalline Si layer with a thickness of about 50 nm doped with an impurity such as phosphorus. The channel layer 50 and the electrode contact layer 51 are formed by patterning these Si layers by a dry etching method using a mixed gas of HCl + SF _{6 or} the like.

Thereafter, as shown in FIG. 20B, a transparent conductive film (ITO) constituting the lower conductive layer 12 is deposited to a thickness of about 150 nm by a sputtering method. Then, A1,
A metal film made of Mo, Ta, or the like is laminated. here,
Ta is used. By patterning these metal layers, a source signal line 43, a source electrode 52, and a drain electrode 53 are formed. Next, the transparent conductive film is patterned to form the lower conductive layer 12. Then, the channel portion of the thin film transistor (TFT) is formed by patterning the electrode contact layer 51 by a dry etching method.

Next, as shown in FIG.
An insulating film made of x or the like is deposited to a thickness of about 600 nm by a CVD method and then patterned to form a first dielectric layer.
(Protective layer) 13a is formed. At the time of patterning, a first opening 13a 'is formed in a region of the gate insulating layer 46 facing the opening 46a. Opening 4 of gate insulating layer 46
By forming both 6a and the first opening 13a ',
The recess 13r can be made deeper. Further, a contact hole 45 for electrically connecting the lower conductive layer 12 and the upper conductive layer 14 is also formed on the auxiliary capacitance wiring 42 at the same time.

The subsequent steps are the same as those shown in FIGS.
As shown in (e), FIGS. 19 (d) and 19 (e)
In the same manner as described with reference to FIG.
a ′ is produced.

Next, the liquid crystal display device 50 shown in FIG.
The method of manufacturing 0 ″ will be described. TFT substrate 500a ''
Structures other than the above are the same as those of the liquid crystal display device 500 illustrated in FIG.

FIGS. 21A to 21 E show the liquid crystal display device 5.
It is sectional drawing which shows typically the manufacturing process of 00 "TFT substrate 500a".

As shown in FIG. 21A, FIG.
The gate electrode 48, the auxiliary capacitance signal line 42, the gate insulating layer 46, the channel layer 50, and the electrode contact layer 51 are formed in the same manner as the above-described process with reference to FIG.

Next, as shown in FIG.
A metal film made of Mo, Ta, or the like is laminated. here,
Ta is used. By patterning these metal layers, a source signal line 43, a source electrode 52, and a drain electrode 53 are formed. Then, the channel portion of the thin film transistor (TFT) is formed by patterning the electrode contact layer 51 by a dry etching method.

Next, as shown in FIG.
After depositing an insulating film made of x or the like by about 600 nm by the CVD method, the first dielectric layer 13a and the gate insulating layer 46 are simultaneously patterned to form the first opening 13a 'and the opening 46a. Adopting this configuration has an additional advantage that the number of photolithography steps can be reduced as compared with the manufacturing method described above with reference to FIG.

Next, a transparent conductive film (ITO) constituting the lower conductive layer 12 is deposited to a thickness of about 150 nm by a sputtering method and then patterned to form the lower conductive layer 12.

The subsequent steps are the same as those shown in FIGS.
As shown in (e), FIGS. 19 (d) and 19 (e)
In the same manner as described with reference to FIG.
a '' is produced.

As described above, the dielectric layer 13 in the liquid crystal display device of the present embodiment has a laminated structure including the first dielectric layer 13a and the second dielectric layer 13b.
a 'on the first dielectric layer 13 having an a'
By forming the second dielectric layer 13b so as to cover the surface, a surface shape reflecting the surface step due to the opening 13a ', that is, the recess 13r is obtained. Therefore, it is not necessary to separately perform a photolithography process in which the exposure amount is adjusted on the dielectric layer 13 formed using the photosensitive resin, so that the process can be simplified and the positional accuracy by the alignment of the photomask can be improved. Does not decrease.
In addition, the accuracy of the depth of the recess 13r is increased.

Further, as the first dielectric layer 13 in which the opening 13a is formed, a film formed as a protective film in a general TFT substrate can be used, and the opening 13a is formed by patterning the protective layer. It is only necessary to change the pattern of the mask used in the step of performing the step, and no additional step is required. Further, even when the opening 46a is formed in the gate insulating film 46, no additional step is required. Of course, another dielectric layer having a similar opening may be added to adjust the depth of the recess. In particular, in the case of forming a transflective liquid crystal display device in which the upper conductive layer 14 is used as a reflective electrode, the thickness of the liquid crystal layer in a reflective region (a region defined by the upper conductive layer 14 and displaying in a reflection mode) is set. The thickness of the liquid crystal layer (corresponding to d1 in FIG. 1) of the liquid crystal layer (corresponding to d2 in FIG. 1) in the transmissive region (region defined by the opening 14a of the upper conductive layer 14 and displaying in the transmissive mode) is about 1 / 2, and in that case, it is preferable to add a separate dielectric layer.

As described above, according to the present embodiment, a liquid crystal display device with excellent display quality, which can be manufactured with high productivity and with good reproducibility, and a method for manufacturing the same are provided. (Embodiment 2) The liquid crystal display device of Embodiment 1 has an opening 1
The dielectric layer 13 having the recess 13r was formed by forming the second dielectric layer 13b on the first dielectric layer 13a having 3a '. On the other hand, as shown in FIG. 22, in the liquid crystal display device 600 of the present embodiment, the dielectric layer 13 ′ having the concave portion 13r is formed without forming the laminated structure including the first dielectric layer having the opening. Is formed.

Referring to FIG. 23, the TF of the liquid crystal display device 600 including the dielectric layer 13 'having the concave portion 13r
A method for manufacturing the T substrate 600a will be described.

As shown in FIGS. 23A and 23B,
In the first embodiment, the gate electrode 48 and the gate electrode 48 are formed in the same manner as the steps described above with reference to FIGS.
Auxiliary capacitance signal line 42, gate insulating layer 46, channel layer 5
0 and the electrode contact layer 51, the source signal line 43, the source electrode 52 and the drain electrode 53, and the lower conductive layer 12 are formed.

Thereafter, as shown in FIG. 23C, a photosensitive resin layer to be a dielectric layer 13 'is formed on almost the entire surface of the substrate. A contact hole 4 for electrically connecting the upper conductive layer 14 and the lower conductive layer 12 is formed in the photosensitive resin layer.
5 is formed. The photosensitive resin layer is formed to a thickness of about 1.5 μm using, for example, a positive photosensitive resin (acrylic resin manufactured by JSR: a relative dielectric constant of 3.7). Note that the dielectric layer 13 'may be formed by a photolithography process using a non-photosensitive resin and a separate photoresist.

Next, as shown in FIG. 23D, a transparent conductive film (ITO) constituting the upper conductive layer 14 is laminated to a thickness of about 100 nm by a sputtering method. After this,
The transparent conductive film is patterned according to a conventional method, and the opening 14 is formed.
The upper conductive layer 14 having a is formed.

Next, as shown in FIG. 23 (e), the upper conductive layer 1 is dry-etched using the upper conductive layer 14 as a mask, for example, using CF ₄ + O ₂ gas.
The concave portion 13r is formed by partially (thickness direction) removing the dielectric layer 13 'in the opening 14a of No.4.
The depth of the recess 13r is controlled by adjusting the etching condition (for example, time).

As described above, the recess 13r of the dielectric layer 13 'in the liquid crystal display device of the present embodiment is formed by partially removing the dielectric layer 13' using the upper conductive layer 14 as a mask. I have. Therefore, it is not necessary to separately perform a photolithography process in which the exposure amount is adjusted on the dielectric layer 13 formed using the photosensitive resin, so that the process can be simplified and the positional accuracy by the alignment of the photomask can be improved. Does not decrease. Also,
The accuracy of the depth of the recess 13r is also increased.

Further, there is an advantage that the process margin is increased from the viewpoint of the chemical resistance of the dielectric layer. When the step of forming the upper conductive layer 14 and the opening 14a is performed after forming the concave portion in the dielectric layer 13 as in the related art, the step of removing the resist used for patterning the upper conductive layer 14 is performed. In the above, the acrylic resin or the like forming the dielectric layer 13 is not highly resistant to a resist stripper (particularly, an amine stripper).
In, it is necessary to control the process conditions so that the floating or peeling does not occur. On the other hand, according to the formation method of the present embodiment, after the upper conductive layer 14 is patterned and the opening 14a is formed, the recess 13r is formed in the dielectric layer 13.
In the step of removing the resist used for patterning the upper conductive layer 14, the concave portion 1 is formed in the dielectric layer 13.
Since 3r is not formed, it is hardly damaged by the resist stripping solution, and the process margin is widened.

The method of forming the recess 13r according to the present embodiment can be used in combination with the method of forming the recess 13r exemplified in the first embodiment. In particular, when configuring a transflective liquid crystal display device using the upper conductive layer 14 as a reflective electrode, a deep recess 13r is required to adjust the thickness of the liquid crystal layer in the reflective region and the thickness of the liquid crystal layer. It is effective in the case. Also, when the reflective electrode (upper conductive layer 14) is formed using Al, the upper conductive layer 1 can be formed by dry etching using, for example, CF ₄ + O ₂ gas.
4 can partially remove the dielectric layer 13 'in the opening 14a. The step of removing the dielectric layer 13 ', in addition to the dry etching method, for example, can be performed by using O ₂ ashing.

[0140]

According to the present invention, an oblique electric field is generated at the edge of the opening of the upper conductive layer by the two-layer structure electrode including the upper conductive layer having the opening, the dielectric layer, and the lower conductive layer. Then, since the liquid crystal molecules of the vertical alignment liquid crystal layer are radially tilt-aligned, the radial tilt alignment can be stably and reproducibly formed. In addition, the dielectric layer
Since there is a concave portion (a region where the height of the dielectric layer is low) in a region corresponding to the upper conductive layer, the relationship between the applied voltage and the retardation can be made uniform at a position in the pixel region,
A liquid crystal display device capable of high-quality display is provided. In particular, as compared with a transmissive display device having a dielectric layer with a flat surface, the transmittance is reduced due to a decrease in the voltage applied to the liquid crystal layer in a region corresponding to the opening of the upper conductive layer (light use efficiency is reduced). Decrease) is suppressed. In addition, when the configuration in which the upper conductive layer has a plurality of openings is employed, a stable radially inclined alignment can be obtained over the entire pixel region, and a liquid crystal display device in which a decrease in response speed is suppressed is provided.

Further, according to the present invention, since the concave portions of the dielectric layer can be formed with good reproducibility by a simple manufacturing process, the above-described liquid crystal display device having excellent display quality can be manufactured with high productivity.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a cross section of one picture element region of a liquid crystal display device 100 according to an embodiment of the present invention.

FIGS. 2 (a) and (b) show other liquid crystal display devices 100 ′ and 100 ″ according to an embodiment of the present invention, respectively.
FIG. 4 is a diagram schematically showing a cross section of one picture element region.

FIGS. 3A, 3B and 3C are cross-sectional views schematically showing one picture element region of a conventional liquid crystal display device 200. FIGS.

FIG. 4 is a cross-sectional view schematically showing one picture element region of the liquid crystal display device 300 for comparison.

FIG. 5 is a diagram schematically showing a relationship between lines of electric force and alignment of liquid crystal molecules.

FIG. 6 is a diagram schematically showing an alignment state of liquid crystal molecules as viewed from a normal direction of a substrate in a liquid crystal display device according to an embodiment of the present invention.

FIGS. 7A and 7B are schematic diagrams showing examples of spiral radially inclined alignment of liquid crystal molecules.

FIG. 8 is a diagram schematically illustrating an example of radially inclined alignment of liquid crystal molecules.

FIG. 9 is a view schematically showing an alignment state of liquid crystal molecules as viewed from a normal direction of the substrate in the liquid crystal display device according to the embodiment of the present invention.

FIG. 10 is a diagram schematically illustrating an example of radially inclined alignment of liquid crystal molecules.

FIG. 11 is a liquid crystal display device 400 according to an embodiment of the present invention.
FIG. 4 is a diagram schematically showing a cross-sectional structure of one picture element region of FIG.

FIGS. 12A to 12C are diagrams schematically showing the relationship between the relative arrangement of a plurality of square openings and the orientation of liquid crystal molecules.

FIGS. 13A to 13C are diagrams schematically showing the relationship between the relative arrangement of a plurality of circular openings and the orientation of liquid crystal molecules.

FIG. 14 is a diagram schematically showing the relationship between another relative arrangement of a plurality of circular openings and the orientation of liquid crystal molecules.

FIG. 15 is a liquid crystal display device 50 according to the first embodiment of the present invention.
FIG. 5 is a plan view schematically showing a picture element region of 0.

FIG. 16 is a schematic sectional view of a picture element region of the liquid crystal display device 500 according to the first embodiment.

FIG. 17 is a schematic sectional view of a picture element region of the liquid crystal display device 500 ′ of the first embodiment.

FIG. 18 is a schematic sectional view of a picture element region of the liquid crystal display device 500 ″ of the first embodiment.

FIG. 19 is a process sectional view of the TFT substrate 500a of the liquid crystal display device 500 according to the first embodiment.

FIG. 20 shows a TFT of the liquid crystal display device 500 ′ of the first embodiment.
It is a process sectional view of substrate 500a '.

FIG. 21 is a diagram illustrating the TF of the liquid crystal display device 500 ″ according to the first embodiment.
It is a process sectional view of T substrate 500a ''.

FIG. 22 is a schematic cross-sectional view of a picture element region of the liquid crystal display device 600 according to the second embodiment.

FIG. 23 is a process sectional view of the TFT substrate 600a of the liquid crystal display device 600 according to the second embodiment.

[Explanation of symbols]

 11, 21 Transparent insulating substrate 12 Lower conductive layer 13, 13 'Dielectric layer 13a First dielectric layer (protective layer) 13a Opening of first dielectric layer 13b Second dielectric layer (photosensitive resin layer) 13r Concave part 14 Upper conductive layer 14a Opening part 15 Pixel electrode (two-layer structure electrode) 22 Counter electrode 30 Liquid crystal layer 30a Liquid crystal molecules 100, 100 ', 100' 'Liquid crystal display device 100a TFT substrate 100b Counter substrate

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kazuhiro Maekawa 22-22 Nagaikecho, Abeno-ku, Osaka City, Osaka Inside (72) Inventor Takashi Ochi 22-22 Nagaikecho, Abeno-ku, Osaka City, Osaka Sharp In-house F term (reference) 2H090 HA04 HB07X KA04 KA18 MA01 MA06 MA13 2H092 JA26 JA29 JA35 JA38 JA42 JA44 JA47 JB13 JB23 JB32 JB33 JB38 JB51 JB57 JB63 JB69 KA05 KA07 KB14 MA05 MA08 MA14 MA15 MA19 MA25 NA27 PA02 QA06 QA18 5C094 AA24 AA42 AA43 AA46 BA03 BA43 CA19 EA04 EA05 EB02 ED02

Claims (11)

[Claims] A first substrate, a second substrate, and a liquid crystal layer provided between the first substrate and the second substrate, wherein the liquid crystal layer is provided on the liquid crystal layer side of the first substrate. A first electrode;
A plurality of picture element regions each defined by a second electrode provided on the second substrate and opposed to the first electrode via the liquid crystal layer, wherein in each of the plurality of picture element regions, The liquid crystal layer assumes a vertical alignment state when no voltage is applied between the first electrode and the second electrode, and
An alignment state is changed according to a voltage applied between the electrode and the second electrode, wherein the first electrode includes a lower conductive layer, a first dielectric layer having a first opening, and the lower conductive layer. A second dielectric layer provided on the first dielectric layer and the first dielectric layer; and an upper conductive layer provided on the liquid crystal layer side of the second dielectric layer, wherein the upper conductive layer has at least one layer. The lower conductive layer is provided so as to face at least a part of the at least one conductive layer opening via the second dielectric layer, and One opening is
The height of the surface of the second dielectric layer located in the opening of the conductive layer is provided corresponding to the opening of the conductive layer, and the height of the second dielectric layer in the region where the upper conductive layer is provided is A liquid crystal display device that is lower than the height of the surface of the body layer. 2. The method according to claim 1, wherein the first dielectric layer is provided on the lower conductive layer, and the first opening is formed so as to expose a part of the lower conductive layer. Item 2. The liquid crystal display device according to item 1. 3. The device according to claim 1, wherein the first dielectric layer is provided below the lower conductive layer, and the lower conductive layer is formed to cover the first opening. Liquid crystal display. 4. The method according to claim 1, wherein the first substrate further includes a third dielectric layer below the lower conductive layer, the third dielectric layer having a second opening in a region corresponding to the conductive layer opening. 3
The liquid crystal display device according to any one of the above. 5. The liquid crystal display device according to claim 4, wherein the first substrate further includes a thin film transistor, and the third dielectric layer also functions as a gate insulating film of the thin film transistor. 6. A first substrate, a second substrate, and a liquid crystal layer provided between the first substrate and the second substrate, wherein the liquid crystal layer is provided on the liquid crystal layer side of the first substrate. A plurality of picture element regions each defined by a first electrode provided on the second substrate and a second electrode provided on the second substrate and facing the first electrode with the liquid crystal layer interposed therebetween. A lower conductive layer, a first dielectric layer having a first opening, a second dielectric layer provided on the lower conductive layer and the first dielectric layer, and the liquid crystal of the second dielectric layer. An upper conductive layer provided on a layer side, wherein the upper conductive layer has at least one conductive layer opening, and the lower conductive layer has the at least one conductive layer opening through the second dielectric layer. A method for manufacturing a liquid crystal display device provided so as to face at least a part of an opening of a conductive layer, the method comprising: Forming a pole; forming a lower conductive layer on the substrate; forming a first dielectric layer having a first opening on the substrate; forming the lower conductive layer and the first dielectric layer on the substrate; Forming a second dielectric layer on the body layer, the surface of a region corresponding to the first opening being lower in surface height than the surface of the other region; Forming an upper conductive layer having a conductive layer opening on the second dielectric layer in a region to be formed. 7. The liquid crystal display device according to claim 6, wherein the first dielectric layer is formed on the lower conductive layer such that the lower conductive layer is exposed in the first opening. Manufacturing method. 8. The lower dielectric layer according to claim 6, wherein the lower conductive layer is formed on the first dielectric layer so as to cover at least the first dielectric layer opening of the first dielectric layer. Of manufacturing a liquid crystal display device. 9. Before the step of forming the lower conductive layer,
9. The method according to claim 6, further comprising: forming a third dielectric layer having a second opening on the substrate. 10. 10. The liquid crystal display device according to claim 9, further comprising a step of forming a thin film transistor on the substrate, wherein the third dielectric layer is formed to also serve as a gate insulating film of the thin film transistor. Manufacturing method. 11. A semiconductor device comprising: a first substrate; a second substrate; and a liquid crystal layer provided between the first substrate and the second substrate.
A first electrode provided on the liquid crystal layer side of the first substrate;
A plurality of picture element regions each defined by a second electrode provided on the second substrate and opposed to the first electrode via the liquid crystal layer, wherein the first electrode has a lower conductive layer; A dielectric layer covering at least a part of the lower conductive layer, and an upper conductive layer provided on the liquid crystal layer side of the dielectric layer, wherein the upper conductive layer has at least one conductive layer opening. A method of manufacturing a liquid crystal display device, wherein the lower conductive layer is provided so as to face at least a part of the opening of the at least one conductive layer via the dielectric layer. Forming a lower conductive layer on the substrate; forming a dielectric film on the lower conductive layer; forming an upper conductive layer having a conductive layer opening on the dielectric film. And, using the upper conductive layer as a mask, Forming a dielectric layer in which the height of the surface of the region corresponding to the first opening is lower than the height of the surface of the other region by partially removing the dielectric film in the conductive layer opening; A method for manufacturing a liquid crystal display device, comprising: