JP2003131248A - Liquid crystal display device and manufacturing method therefor, and substrate therefor, and electronic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device capable of improving an alignment property of a liquid crystal by improving disturbed alignment direction of the liquid crystal due to ruggedness caused by a plane form of electrodes. SOLUTION: The liquid crystal display device is made up so that an insulating film 17 is embedded between electrode fingers 6a, and a step difference between the upper face of a 2nd electrode 6 and that of the insulating film 17 is smaller than the film thickness of the 2nd electrode 6.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a liquid crystal display device, a method for manufacturing the liquid crystal display device, a substrate for the liquid crystal display device,
More particularly, the present invention relates to a liquid crystal display device which can improve the orientation of liquid crystals and is excellent in display quality, a manufacturing method thereof, a substrate for a liquid crystal display device, and an electronic device.

[0002]

2. Description of the Related Art Conventionally, as one means for increasing the viewing angle of a liquid crystal display device, an in-plane lateral electric field is generated with respect to a substrate, and this lateral electric field causes liquid crystal molecules to be in a plane parallel to the substrate. In-Plane Switching (hereinafter referred to as “In-Plane Switching”)
Abbreviated as "IPS". ) Technology has been put to practical use. And in recent years, fringe field switching (Fringe-Field Switching,
Hereinafter, it is abbreviated as “FFS”. ) Technology is "High-Transm
ittance, Wide-Viewing-Angle Nematic Liquid Crystal
Display Controlled by Fringe-Field Switching ", S.
H. Lee et al., ASIA DISPLAY 98, p.371-374, "A High
Quality AM-LCD using Fringe-Field Switching Techno
logy ", SHLee et al., IDW'99, p.191-194.

The FFS technique described in this specification will be described below. FIG. 12 is a diagram showing the difference in concept between IPS and FFS. FIG. 12 (a) is IPS and FIG. 12 (b).
Indicate FFS, respectively. In IPS and FSS, as shown in FIGS. 12A and 12B, the liquid crystal molecule 202 between the pair of substrates 200 and 201 is driven by the lateral electric field E by the pair of electrodes 203 and 204. Is the same. However, the cell gap is d, the electrode width is w,
If the distance between the electrodes is l, the relationship between these dimensions is IP
In S, 1 / d> 1 and 1 / w> 1, whereas FF
In S, 1 / d <1 and 1 / w <1, or 1 / d = 0 and 1 / w = 0. That is, in the IPS, the inter-electrode distance is larger than the cell gap and the electrode width, whereas the FF
In S, the distance between electrodes is smaller than the cell gap or the electrode width (the electrode 203 and the electrode 2 in the IPS of FIG. 12A).
04 is sufficiently close) or the inter-electrode distance is 0. In other words, in FFS, FIG.
As shown in (b), an electrode configuration is adopted in which the other electrode 203 (+ pole) is laminated above one electrode 204 (− pole) via the insulating layer 205.

The direction of the generated electric field is slightly changed due to the difference in the electrode structure, and the electric field direction in IPS is the direction in which the electrodes face each other (y direction in the figure).
In the electrode structure of 2 (b), since the electrodes 203 and 204 are laminated, in addition to the lateral direction (Y direction in the drawing),
In particular, it has a strong electric field component in the direction perpendicular to the substrate surface (Z direction in the drawing) near the edge of the electrode 203. As a result, I
In PS, liquid crystal molecules 2 located between the electrodes 203 and 204
02 is driven, the liquid crystal molecules 202 located above the electrodes 203 and 204 are hardly driven.
In the case of, not only the liquid crystal molecules positioned between the electrodes 203, 203 but also the liquid crystal molecules 202 positioned above the electrode 203.
Will also be driven. Therefore, in the FFS, if the electrode is formed of a transparent conductive film such as indium tin oxide (hereinafter abbreviated as “ITO”), the electrode portion can also contribute to the display, and the same. It has an advantage that the aperture ratio can be increased as compared with the IPS of the conditions.

[0005]

However, in the above-mentioned IPS and FFS, irregularities due to the film thickness of the electrodes are formed on the substrate 201 toward the liquid crystal side. That is, the electrodes are flat in the method using the normal longitudinal electric field, but in the IPS and the FFS, the electrodes are comb-shaped, so that in the IPS, the substrate 20 is formed as shown in FIG.
1 is formed on the substrate 201 toward the liquid crystal side with a step difference corresponding to the film thickness of the electrodes 203 and 204 due to the electrodes 203 and 204, and in FFS, as shown in FIG. Electrode 203 toward the liquid crystal side
As a result, unevenness having steps corresponding to the film thickness of the electrode 203 is formed. Since the unevenness due to the shape of the electrode disturbs the alignment direction of the liquid crystal molecules 202,
There is a problem that it causes display defects such as deterioration of contrast and light leakage.

The present invention has been made to solve the above problems, and in a liquid crystal display device driven by a lateral electric field, the disturbance of the alignment direction of the liquid crystal due to the unevenness due to the film thickness of the electrodes is improved. Then, an object of the present invention is to provide a bright liquid crystal display device capable of improving the orientation of the liquid crystal and excellent in display quality, and a manufacturing method thereof. It is another object of the present invention to provide a substrate for a liquid crystal display device used in the above liquid crystal display device, and an electronic apparatus including the above liquid crystal display device having excellent display quality.

[0007]

In order to achieve the above-mentioned object, a liquid crystal display device of the present invention is a liquid crystal display device in which liquid crystal is sandwiched between a pair of substrates facing each other. An electrode and a switching element are provided on one of the substrates, and the electrode is a first electrode and a plurality of electrode fingers formed above the first electrode via an interlayer insulating layer. And a switching element electrically connected to either the first electrode or the second electrode, and the liquid crystal is generated at the first electrode and the second electrode. Driven by the transverse electric field
An insulating film is embedded between the electrode fingers, and a step between the upper surface of the second electrode and the upper surface of the insulating film is smaller than the film thickness of the second electrode.

In a conventional liquid crystal display device provided with a substrate for generating a lateral electric field, there is always unevenness having steps corresponding to the film thickness of electrodes, whereas in the liquid crystal display device of the present invention, electrode fingers An insulating film is embedded between them, and the step between the upper surface of the second electrode and the upper surface of the insulating film is smaller than the film thickness of the second electrode. Therefore, as shown in Examples described later, The disorder of the alignment direction is improved, and the alignment property of the liquid crystal can be improved. Further, the liquid crystal display device of the present invention is a liquid crystal display device provided with a substrate that generates a lateral electric field, and since the lateral electric field is used to drive the liquid crystal, the viewing angle can be widened and disclination can be prevented. In addition, defects such as light leakage do not occur. Therefore, according to the liquid crystal display device of the present invention, a liquid crystal display device that is bright and has excellent display quality can be realized.

In the above liquid crystal display device, the second electrode is formed above the first electrode via the interlayer insulating layer and has a plurality of electrode fingers. The FFS can be easily arranged as
It is possible to realize a liquid crystal display device that adopts the method electrode arrangement.

In the above liquid crystal display device, the first
As the arrangement of the electrode and the second electrode, the FFS type electrode arrangement may not be adopted, but it is preferable to adopt the FFS type electrode arrangement. When the FFS type electrode arrangement is adopted, the liquid crystal molecules located above the electrodes can be driven in a good alignment state, and the electrodes are formed of a transparent conductive film, and the electrode portions also contribute to the display. In this case, the aperture ratio can be increased and a liquid crystal display device which is bright and has excellent display quality can be realized as compared with the case where an IPS type substrate under the same conditions is used.

Further, in the case of adopting the FFS system, if the cell gap is d, the electrode width is w, and the electrode distance is l,
A configuration of 1 / d <1 and 1 / w <1 may be adopted, that is, a configuration in which the interelectrode distance is smaller than the cell gap and the interelectrode distance is smaller than the electrode width. By using such a liquid crystal display device, a liquid crystal display device which is brighter and has excellent display quality can be realized.

In the above liquid crystal display device, it is desirable that the surface formed by the upper surface of the second electrode and the upper surface of the insulating film is substantially flat. In the liquid crystal display device of the present invention, “generally flat” also includes the case where there are unintended irregularities due to an error during manufacturing. By using such a liquid crystal display device, it is possible to more effectively improve the disorder of the alignment direction of the liquid crystal molecules and improve the alignment property of the liquid crystal.

Further, in the above liquid crystal display device, it is desirable that the first electrode is provided on the entire surface of the one substrate.

By using such a liquid crystal display device, F
When adopting the FS method, if the cell gap is d, the electrode width is w, and the distance between electrodes is l, then 1 / d = 0 and 1 / w
= 0 (l = 0) can be adopted, and the area of the first electrode can be wide (for example, the first electrode is solid).
be able to. Therefore, when the second electrode is formed of a transparent conductive film, the first electrode is formed of a metal film, and the first electrode functions not only as an electrode but also as a reflection layer, another reflection layer or an external It is possible to realize a reflective liquid crystal display device without adding a reflection plate or the like.

Further, in the above-mentioned liquid crystal display device, the first electrode and the second electrode have a plurality of electrode fingers, and the electrode finger of the second electrode is a plane electrode of the first electrode. It may be arranged at a position between the electrode fingers.

In order to achieve the above object, a method of manufacturing a liquid crystal display device of the present invention is a manufacturing method of manufacturing any one of the above liquid crystal display devices, wherein one of the pair of substrates is used. Forming a first electrode on the substrate of
Forming a second electrode having a plurality of electrode fingers above the first electrode via an interlayer insulating layer; forming an insulating layer on the entire surface of the second electrode; and the second electrode By polishing the insulating layer until the surface of
And a step of forming an insulating film between the electrode fingers. According to such a method of manufacturing a liquid crystal display device, it is possible to obtain a liquid crystal display device in which the surface formed by the upper surface of the second electrode and the upper surface of the insulating film is substantially flat, and the alignment state of the liquid crystal is easily good. It is possible to obtain the above liquid crystal display device which is bright and has excellent display quality.

In order to achieve the above object, a method of manufacturing a liquid crystal display device of the present invention is a manufacturing method of manufacturing any one of the above liquid crystal display devices, wherein one of the pair of substrates is used. Forming a first electrode on the substrate of
Forming an insulating layer on the upper side of the first electrode and removing a part of the insulating layer in the thickness direction to form a comb-shaped recess in plan view on the surface of the insulating layer; A conductive layer is formed on the surface of the layer, and the conductive layer is polished until the surface of the insulating layer is exposed to form a second electrode having a plurality of electrode fingers, and between the electrode fingers. And a step of forming an insulating film. Also by such a method for manufacturing a liquid crystal display device, a liquid crystal display device in which the surface formed by the upper surface of the second electrode and the upper surface of the insulating film is substantially flat is obtained, and the alignment state of the liquid crystal is easily good. It is possible to obtain the above liquid crystal display device which is bright and has excellent display quality.

In order to achieve the above object, the liquid crystal display device of the present invention is a liquid crystal display device in which liquid crystal is sandwiched between a pair of substrates facing each other, and one of the pair of substrates. An electrode and a switching element are provided on the substrate of, and the electrode includes a first electrode and a second electrode provided in the same layer as the first electrode, and the first electrode and the second electrode are provided. Has a plurality of electrode fingers, the electrode finger of the second electrode is arranged at a position between the electrode fingers of the first electrode, and the switching element is of the first electrode or the second electrode. The liquid crystal is electrically connected to one of the electrodes, and the liquid crystal is driven by a horizontal electric field generated by the first electrode and the second electrode, and between the adjacent first electrode and second electrode, An insulating film is embedded on the first electrode and the second electrode. And the step between the upper surface of the insulating film may be characterized in that less than the thickness of the first electrode and the second electrode.

In the liquid crystal display device of the present invention, the "same layer as the first electrode" means a layer provided at the same time in the step of providing the first electrode. Therefore, it is a layer made of the same material as the first electrode and having the same film thickness.

In the above liquid crystal display device, the insulating film is embedded between the first electrode and the second electrode which are adjacent to each other, and the step between the upper surfaces of the first electrode and the second electrode and the upper surface of the insulating film is the first. Since the thickness is smaller than the film thickness of the electrode and the second electrode, the disorder of the alignment direction of the liquid crystal molecules is improved, and the alignment property of the liquid crystal can be improved. In addition, this liquid crystal display device is also a liquid crystal display device having a substrate that generates a lateral electric field, and since the lateral electric field is used to drive the liquid crystal, the viewing angle can be widened and no disclination occurs. No defects such as leakage will occur. Therefore, according to the liquid crystal display device of the present invention, a liquid crystal display device that is bright and has excellent display quality can be realized.

Further, in the above liquid crystal display device, the electrodes are the first electrode and the second electrode provided in the same layer as the first electrode.
An electrode, and the first electrode and the second electrode are
It has a plurality of electrode fingers, the electrode finger of the second electrode is arranged at a position between the electrode fingers of the first electrode,
It is possible to realize a liquid crystal display device in which an IPS type electrode arrangement is adopted as the arrangement of the first electrode and the second electrode.

In the above liquid crystal display device, it is desirable that the surface formed by the upper surfaces of the first electrode and the second electrode and the upper surface of the insulating film is substantially flat. By using such a liquid crystal display device, it is possible to more effectively improve the disorder of the alignment direction of the liquid crystal molecules and improve the alignment property of the liquid crystal.

Further, in any of the above liquid crystal display devices, it is desirable that the liquid crystal has a positive dielectric anisotropy. In the liquid crystal display device of the present invention, the liquid crystal may have a positive dielectric anisotropy or a negative dielectric anisotropy, but the dielectric anisotropy is more preferable. . By using such a liquid crystal display device, as compared with the case where a liquid crystal having a negative dielectric anisotropy is adopted, the driving voltage can be easily lowered, and the response characteristics are excellent.
Disturbance of the alignment direction of the liquid crystal molecules can be more effectively improved, and the alignment of the liquid crystal can be improved.

In order to achieve the above object, the substrate for a liquid crystal display device of the present invention is provided with an electrode and a switching element on the substrate, and the electrode includes a first electrode and a first electrode. Also includes a second electrode having a plurality of electrode fingers formed on the upper side with an interlayer insulating layer interposed therebetween, and the switching element is electrically connected to either the first electrode or the second electrode. An insulating film is embedded between the electrode fingers, and a step between the upper surface of the second electrode and the upper surface of the insulating film is smaller than the film thickness of the second electrode.

By adopting such a substrate for a liquid crystal display device as one of a pair of substrates constituting the liquid crystal display device, the alignment state of the liquid crystal is good, and the display is bright and excellent in display quality. A liquid crystal display device can be obtained.

In order to achieve the above object, the liquid crystal display device substrate of the present invention is provided with an electrode and a switching element on the substrate, and the electrode is the same as the first electrode and the first electrode. The second electrode provided on one layer, and the first electrode
The electrode and the second electrode have a plurality of electrode fingers, the electrode finger of the second electrode is arranged at a position between the electrode fingers of the first electrode, and the switching element is the first electrode. Alternatively, it is electrically connected to any one of the second electrodes, and between the adjacent first electrode and second electrode,
An insulating film is embedded, and a step between the upper surfaces of the first electrode and the second electrode and the upper surface of the insulating film is smaller than the film thickness of one or both of the first electrode and the second electrode. It may be a substrate for a liquid crystal display device.

By adopting such a substrate for a liquid crystal display device as one of a pair of substrates constituting the liquid crystal display device, the alignment state of the liquid crystal is good,
It is possible to obtain the above liquid crystal display device which is bright and has excellent display quality.

In order to achieve the above object, the electronic equipment of the present invention is characterized by including any one of the above liquid crystal display devices. By using such an electronic device, an electronic device including a liquid crystal display unit with high brightness and high contrast can be realized.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] A first embodiment of the present invention will be described below with reference to the drawings. The liquid crystal display device of this embodiment employs an example of the liquid crystal display device substrate of the present invention as a lower substrate. The liquid crystal display device of the present embodiment is particularly characterized in that an insulating film is embedded between the electrode fingers that form the second electrode. FIG. 1 is a plan view showing a configuration of a lower substrate in the liquid crystal display device of the present embodiment, and FIG. 2 is a cross-sectional view enlarging a part of the liquid crystal display device of the present embodiment. In all of the following drawings, in order to make the drawings easy to see, the film thicknesses, the dimensional ratios, and the like of the respective constituent elements are appropriately changed.

As shown in FIG. 2, the liquid crystal display device of the present embodiment has a positive dielectric anisotropy between a pair of substrates including an upper substrate 7 and a lower substrate 1 having an FFS type electrode structure. The liquid crystal 22 is sandwiched.

As shown in FIG. 1, the lower substrate 1 has a plurality of data lines 2 extending in the vertical direction in FIG. 1 and a plurality of gate lines 3 extending in the horizontal direction in FIG. Are arranged in a matrix. In the lower left part of each pixel in FIG. 1, the gate line 3 branches toward the inside of the pixel to form a gate electrode 4, and a thin film transistor 5 (Thin Film Transistor, hereinafter abbreviated as “TFT”) for pixel switching. I am configuring.

One terminal of the source and the drain of the TFT of each pixel is connected to the data line 2, and the other terminal is connected to the first electrode 14 separated for each pixel region. The first electrode 14 is formed on the insulating layer deposited on the data line 2, the gate line 3 and the TFT 5, and is connected to the drain terminal of the TFT 5 via the contact hole 5a. A comb-teeth-shaped second electrode 6 having a plurality of electrode fingers 6a (6 in FIG. 1 per pixel) extending in the vertical direction in FIG. 1 is provided, and each electrode finger of the second electrode 6 is provided. A portion connecting the 6a partially overlaps the gate line 3 in a plane.

As shown in FIG. 1, the second electrodes 6 are connected to each other between the pixels, and are kept at a constant potential in the entire display area. The region surrounded by the data line 2 and the gate line 3 constitutes one pixel of the liquid crystal display device of this embodiment.

Further, FIG. 2 shows A of the lower substrate 1 shown in FIG.
It is a cross-sectional structure in the −A ′ part. Here, the first electrode 14
Is formed of a metal film having high reflectance such as aluminum and silver, is electrically connected to the pixel switching TFT 5 (not shown in FIG. 2), functions as an electrode, and also serves as a reflection layer. Also works. Therefore, this liquid crystal display device is a reflective liquid crystal display device, and external light is incident from the upper substrate 7 side.

An interlayer insulating layer 15 made of a translucent material is formed on the first electrode 14, and a transparent conductive film such as ITO having a film thickness of about several 1000 nm is formed on the interlayer insulating layer 15. 2, the second electrode 6 having a plurality of electrode fingers 6a extending in the direction penetrating the paper surface is formed, and the surface of the second electrode 6 and the insulating film 1 are formed between the electrode fingers 6a.
The insulating film 17 is embedded so that the surface formed by the surface of the insulating film 7 and the surface of the insulating film 7 is substantially flat.

An alignment film 16 is formed on the second electrode 6 and the insulating film 17. As the material of the alignment film 16, polyimide, a surfactant, a coupling agent,
A metal complex or the like can be used. Further, it is also possible to use an alignment film including a metal film and a monomolecular film formed on the surface of the metal film by a sulfur compound molecule having a linear structure. Although the rubbing process may or may not be performed, when the rubbing process is performed, the rubbing direction is orthogonal to the extending direction of the electrode fingers 6a in order to match the tilt direction of liquid crystal molecules when a voltage is applied, which will be described later. Is desirable.

On the other hand, looking at the cross-sectional structure of the upper substrate 7, on the transparent substrate 27 made of glass or the like, for example, R (red), G
A color filter 18 including a colored layer of each of (green) and B (blue) and a light shielding layer (black matrix) is formed, and an insulating layer 20 made of a translucent material is formed on the color filter 18. An alignment film 21 is formed on the insulating layer 20.
Are formed. The material of the alignment film 21 may be the same as that of the lower substrate 1 side.

In the case of this embodiment, the lower substrate 1 has a first
An FFS type electrode configuration is adopted in which the second electrode 6 is laminated above the electrode 14 with the interlayer insulating layer 15 interposed therebetween. Therefore, the liquid crystal 22 is driven by the lateral electric field E generated by the first electrode 14 and the second electrode 6 of the lower substrate 1. here,
As an example of the dimensions of each part constituting the liquid crystal display device of the present embodiment, the pitch of one pixel is 150 to 200 nm, the cell gap d is 48 to 64 nm, and each electrode finger 6 of the second electrode 6 is shown.
The width w of a is 20 to 40 nm, and the distance m between the electrode fingers 6a of the second electrode 6 is 30 to 60 nm. Preferably, the pitch of one pixel is 150 nm, the number of electrode fingers 6a of the second electrode 6 is 3 to 4, and the width w of each electrode finger 6a of the second electrode 6 is 20 n.
m, the distance m between the electrode fingers 6a of the second electrode 6 is 30 to 40n.
m. It should be noted that the inter-electrode distance l described in the section [Prior Art] corresponds to the interval between the first electrode 14 and the second electrode 6, and therefore l = 0 in the example shown in the present embodiment. , F
The conditions of the FS method are satisfied.

Next, the operation of the liquid crystal display device of this embodiment will be described with reference to FIGS. 3 and 4. 3 and 4, the alignment film is omitted in order to make the drawings easier to see. 3A and 3B are diagrams showing the state of liquid crystal molecules in the state where no voltage is applied, together with the second electrode and the insulating film, FIG. 3A is a plan view, and FIG. 3B is a sectional view. As shown in FIGS. 3A and 3B, the lower substrate 1 and the upper substrate are in a state where no voltage is applied between the first electrode 14 and the second electrode 6 (state in which no voltage is applied). Alignment films 16 and 2 respectively provided on the surface of
By 1, the major axis direction of the liquid crystal molecule 23 is aligned with the extending direction of the electrode finger 6a of the second electrode 6. As a result, black is displayed in the state where no voltage is applied.

FIG. 4 is a diagram showing the state of liquid crystal molecules under a voltage applied state together with the second electrode and the insulating film. FIG. 4 (a) is a plan view and FIG. 4 (b) is a cross section. It is a figure. As shown in FIGS. 4A and 4B, the first
When a voltage is applied between the electrode 14 and the second electrode 6 (voltage application state), the liquid crystal molecules 2 located on the insulating film 17 are
The major axis direction of 3 is oriented in a direction orthogonal to the extending direction of the electrode fingers 6a of the second electrode 6. In addition, the major axis direction of the liquid crystal molecules 23 located on the second electrode 6 is also the electrode finger 6 a of the second electrode 6.
Is oriented in a direction orthogonal to the extending direction of the. As a result, white display is obtained when the voltage is applied.

Next, an example of the method of manufacturing the liquid crystal display device of this embodiment will be described in detail with reference to the drawings. FIG. 5 is a diagram for explaining a part of an example of the method for manufacturing the liquid crystal display device of the present invention, and is a cross-sectional view showing a portion corresponding to the liquid crystal display device shown in FIG. As described above, in the liquid crystal display device and the liquid crystal display device substrate of the present invention, the insulating film 17 is provided between the electrode fingers 6 a forming the second electrode 6.
Since it is particularly characteristic that the insulating film 17 is embedded, in this embodiment, only the step of providing the insulating film 17 will be described in detail with reference to the drawings, and a method similar to the conventional method can be adopted. Detailed description of the steps before providing the insulating film 17 and the steps after providing the insulating film 17 will be omitted. In FIG. 5, the same components as those in FIG. 2 are designated by the same reference numerals.

First, a method of manufacturing the lower substrate 1, which is an example of the liquid crystal display device substrate of the present invention, will be described. First, the pixel switching TFT 5 (not shown in FIG. 5) is formed on the transparent substrate 13 made of glass or the like by using a method similar to the conventional method. Then, Fig. 5
As shown in (a), T
The transparent substrate 1 includes the first electrode 14 electrically connected to the FT5.
3 Provide on the entire surface. The first electrode has a shape separated for each pixel by patterning. After that, FIG.
As shown in (b), the interlayer insulating layer 15 is formed on the first electrode 14.
To form.

Subsequently, as shown in FIG. 5C, a transparent conductive film 6b of ITO or the like is formed on the entire surface of the interlayer insulating layer 15 and patterned, so that as shown in FIG. 6A. In FIG. 6, the second electrode 6 having a plurality of electrode fingers 6a extending in a direction penetrating the paper surface is formed.

Next, as shown in FIG. 6B, the insulating layer 1
7a is formed on the entire surface and is polished by a chemical mechanical polishing (CMP) method until the surface of the second electrode 6 is exposed, so that insulation is provided between the electrode fingers 6a as shown in FIG. 6C. The film 17 is formed, and the surface formed by the surface of the second electrode 6 and the surface of the insulating film 17 becomes substantially flat. In the CMP method used for polishing here, it is usually 1
An error of about 0% occurs. Therefore, in the present embodiment, that the surface formed by the surface of the second electrode 6 and the surface of the insulating film 17 is “generally flat” means about 10% of the film thickness of the insulating layer 17a polished by the CMP method. It also includes the case where there are unintended irregularities due to the error of.

After that, the alignment film 16 is formed on the second electrode 6 and the insulating film 17, and the lower substrate 1 of this embodiment is manufactured.

Next, a method of manufacturing the upper substrate 7 will be described. First, the upper substrate 7 of this embodiment is manufactured by sequentially forming the color filter 18, the insulating layer 20, and the alignment film 21 on the transparent substrate 27 made of glass or the like by using the same method as the conventional one. It

Finally, the lower substrate 1 manufactured as described above.
The upper substrate 7 and the upper substrate 7 are attached to each other with a sealing material so that the alignment film 16 and the alignment film 21 face each other, and the liquid crystal 22 is sucked into the space between the two substrates by a method such as a vacuum suction method, and a predetermined amount By forming a liquid crystal layer having a thickness,
The liquid crystal display device shown in FIG. 2 is manufactured.

In the liquid crystal display device of the present embodiment, the insulating film 17 is provided between the electrode fingers 6a so that the surface formed by the surface of the second electrode 6 and the surface of the insulating film 17 is substantially flat. Since it is embedded, the disorder of the alignment direction of the liquid crystal molecules 23 is improved, and as shown in the examples described later, the liquid crystal located on the second electrode 6 is compared with the case where the insulating film 17 is not provided. The long axis direction of the molecule 23 is accurately oriented in a direction orthogonal to the extending direction of the electrode finger 6a of the second electrode 6 in the voltage applied state. As a result, the amount of light absorbed by the liquid crystal layer is extremely small, and bright white display can be obtained. Also,
In the liquid crystal display device according to the present embodiment, since the horizontal electric field is used to drive the liquid crystal 22, the viewing angle can be widened, and disclination does not occur and defects such as light leakage do not occur. As described above, according to the liquid crystal display device of the present embodiment, a bright liquid crystal display device having excellent display quality can be realized.

Further, in the liquid crystal display device of the present embodiment, the FFS type electrode arrangement is adopted as the arrangement of the first electrode 14 and the second electrode 6 on the lower substrate 1, and the second electrode 6 is made of a transparent conductive film. Since the liquid crystal molecules 23 located above the second electrode 6 can be driven in a good alignment state and the part on the second electrode 6 can be contributed to the display, the same conditions are satisfied. As compared with the case of using the IPS type substrate, the aperture ratio can be increased, and a liquid crystal display device that is bright and has excellent display quality can be realized.

Further, among the electrode arrangements of the FFS system, in particular, in the liquid crystal display device of the present embodiment, since the laminated structure is used, the first electrode 14 is formed of a metal film so that it can be used only as an electrode. Since it can be made to function as a reflection layer without using the FFS method, a reflection type liquid crystal display device can be extremely rationalized without adding a reflection layer or an external reflection plate separately from the first electrode 14. Can be realized.

Further, in the liquid crystal display device of the present embodiment, since the distance m between the electrode fingers 6a of the second electrode 6 is 30 to 40 nm, the disturbance of the alignment direction of the liquid crystal molecules 23 is improved more effectively. The orientation of the liquid crystal 22 can be improved. In addition, high-definition display is possible.

Further, in the liquid crystal display device of this embodiment, since the liquid crystal 22 has a positive dielectric anisotropy, the driving voltage is lower than that in the case of using a liquid crystal having a negative dielectric anisotropy. Since the voltage can be easily applied and the response characteristics are excellent, the disturbance in the alignment direction of the liquid crystal molecules 23 can be more effectively improved, and the alignment property of the liquid crystal 22 can be improved.

Further, in the method of manufacturing the liquid crystal display device of the present embodiment, after the second electrode 6 having the plurality of electrode fingers 6a is formed on the lower substrate 1, the insulating layer 17a is formed on the entire surface, and the second electrode 6 is formed.
This is a method of forming the insulating film 17 between the electrode fingers 6a by polishing until the surface of the electrode 6 is exposed. Therefore, the surface formed by the surface of the second electrode 6 and the surface of the insulating film 17 is generally formed. A flat liquid crystal display device can be obtained, and a liquid crystal display device in which the alignment state of the liquid crystal 22 is good and which is bright and excellent in display quality can be easily obtained.

The method of manufacturing the liquid crystal display device of the present invention is not limited to the above-mentioned manufacturing method, and examples thereof include the following method. Another example of the method for manufacturing the liquid crystal display device of the present embodiment will be described in detail below with reference to the drawings. FIG. 7 is a view for explaining a part of another example of the method for manufacturing a liquid crystal display device of the present invention, and is a cross-sectional view showing a portion corresponding to the liquid crystal display device shown in FIG. is there.

The method of manufacturing the liquid crystal display device shown in FIG.
Since only the step of providing the insulating film 17 is different from the method of manufacturing the liquid crystal display device shown in FIGS. 5 and 6 described above, only the step of providing the insulating film 17 will be described in detail here with reference to the drawings. Detailed description of steps before the insulating film 17 is provided and steps after the insulating film 17 is provided is omitted. Note that, also in FIG. 7, the same components as those in FIG. 2 are denoted by the same reference numerals.

The first electrically connected to the TFT 5 is formed by using the method for manufacturing the liquid crystal display device shown in FIG.
The electrode 14 is formed on the transparent substrate 13 by patterning into a shape separated for each pixel, and the insulating layer 15 is formed over the entire surface of the first electrode 14 as shown in FIG.
a is formed. In the insulating layer 15a, a slight recess is formed in the separated portion of the first electrode corresponding to the boundary of each pixel. It should be noted that this recess is a portion other than the display area of the pixel, and therefore, in the case of a direct-view display having a large pixel size, the display quality is hardly affected even as it is. However, if the pixel size of the light valve, which is the display engine of the projection display, is 20 μm or less, the unevenness between the pixels may affect the light leakage of the pixel portion. In such a case, the recesses between the pixels may be flattened by a polishing process.
Then, a part of the insulating layer 15a is removed in the thickness direction by a method such as forming a photoresist pattern having a predetermined shape on the insulating layer 15a and then etching the same, as shown in FIG. 7B. Then, the insulating layer 15b is formed in which a concave portion having a comb shape in plan view is formed on the surface of the insulating layer 15a.

Next, as shown in FIG. 7C, the insulating layer 1
Conductive layer 6b made of a transparent conductive film such as ITO on the surface of 5b
Is formed on the entire surface, and C is formed until the surface of the insulating layer 15b is exposed.
By polishing the conductive layer 6b using the MP method, as shown in FIG.
As shown in (d), the second electrode 6 having a plurality of electrode fingers 6a extending in a direction penetrating the plane of the drawing in FIG.
Is formed, the insulating film 17 is formed between the electrode fingers 6a, and the surface formed by the surface of the second electrode 6 and the surface of the insulating film 17 becomes substantially flat. In the manufacturing method of the liquid crystal display device shown in FIG. 7, a surface formed by the surface of the second electrode 6 and the surface of the insulating film 17 is “generally flat” means that the conductive layer is polished by the CMP method. 6b
It also includes the case where there are unintended irregularities due to an error of about 10% of the film thickness of.

By the method of manufacturing a liquid crystal display device as described above, a liquid crystal display device in which the surface formed by the surface of the second electrode 6 and the surface of the insulating film 17 is substantially flat can be obtained, and the liquid crystal 22 can be easily formed. It is possible to obtain a liquid crystal display device which has a good alignment state and is bright and excellent in display quality.

[Second Embodiment] A second embodiment of the present invention will be described below with reference to the drawings. In the above-described first embodiment, an example of the reflection type liquid crystal display device employing the FFS type electrode configuration has been described.
An example of a transmissive liquid crystal display device that employs an S-type electrode configuration will be described. FIG. 7 is an enlarged cross-sectional view of a part of the liquid crystal display device of the present embodiment. The liquid crystal display device of the present embodiment is different from the liquid crystal display device of the first embodiment described above only in the material of the first electrode and the adoption of an IPS type electrode configuration as the electrode configuration. Therefore, in FIG. 7, the same components as those in FIG. 2 are designated by the same reference numerals, and detailed description of the common parts will be omitted.

Looking at the cross-sectional structure of the lower substrate 1 constituting the liquid crystal display device of this embodiment, as shown in FIG. 8, a transparent conductive film such as ITO is formed on the transparent substrate 13, and the first electrode 32 is formed. And the second electrode 31 is formed. First electrode 3
The second electrode 31 and the second electrode 31 each have a plurality of electrode fingers 31a and 32a extending in a direction penetrating the plane of the drawing in FIG. 8, and the electrode finger 31a of the second electrode 31 is a first electrode in plan view. It is arranged at a position between the 32 electrode fingers 32a. In addition, between the first electrode 32 and the second electrode 31 which are adjacent to each other,
The insulating film 37 is embedded so that the surfaces formed by the surfaces of the first electrode 32 and the second electrode 31 and the surface of the insulating film 37 are substantially flat.

In the case of this embodiment, the lower substrate 1 has the first
The electrode configuration of the IPS system in which the electrode 32 and the second electrode 31 are arranged side by side is adopted. Therefore, the liquid crystal 22
Are driven by a lateral electric field E generated by the first electrode 32 and the second electrode 31 of the lower substrate 1. In the case of this embodiment,
As shown in FIG. 8, the first electrode 32 and the second electrode 31 are arranged side by side, and the pixel size is on the order of 100 μm and the cell gap is about several μm.
The distance 1 to the electrode 31 is sufficiently large with respect to the cell gap d and the electrode width w, and satisfies the condition for the IPS system electrode configuration.

In the liquid crystal display device of this embodiment, the surfaces of the first electrode 32 and the second electrode 31 and the surface of the insulating film 37 are formed between the first electrode 32 and the second electrode 31 which are adjacent to each other. The insulating film 3 so that the exposed surface is substantially flat.
Since 7 is embedded, the disorder of the alignment direction of the liquid crystal molecules 23 is improved, and liquid crystal molecules positioned on the first electrode 32 and the second electrode 31 are compared with the case where the insulating film 37 is not provided. The major axis direction of 23 is accurately oriented in a direction orthogonal to the extending direction of the electrode fingers 31a, 32a of the first electrode 32 and the second electrode 31 in a voltage applied state. as a result,
The light absorbed by the liquid crystal layer is extremely small, and a bright white display is obtained.

Also, in the liquid crystal display device of the present embodiment, since the horizontal electric field is used to drive the liquid crystal 22, the viewing angle can be widened, and disclination does not occur, and defects such as light leakage occur. There is nothing to do. As described above, the liquid crystal display device of the present embodiment can also obtain the same effect as that of the first embodiment.

[Electronic Equipment] Hereinafter, examples of electronic equipment provided with the liquid crystal display device of the above embodiment will be described. Figure 9
FIG. 4 is a perspective view showing an example of a mobile phone. In FIG. 9, reference numeral 1000 indicates a mobile phone body, and reference numeral 1001.
Indicates a liquid crystal display unit using the above liquid crystal display device.

FIG. 10 is a perspective view showing an example of a wrist watch type electronic device. In FIG. 10, reference numeral 1100 indicates a watch body, and reference numeral 1101 indicates a liquid crystal display unit using the above liquid crystal display device.

FIG. 11 is a perspective view showing an example of a portable information processing device such as a word processor and a personal computer. In FIG. 11, reference numeral 1200 is an information processing apparatus, reference numeral 1202 is an input unit such as a keyboard, reference numeral 1204 is the information processing apparatus main body, and reference numeral 1206 is a liquid crystal display unit using the above liquid crystal display device.

Since the electronic equipment shown in FIGS. 9 to 11 is equipped with the liquid crystal display section using the liquid crystal display device of the above-mentioned embodiment, it is possible to realize the electronic equipment provided with the bright and excellent display quality. be able to.

The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the above-described embodiment, an example of a reflective type color liquid crystal display device and a transmissive type color liquid crystal display device has been shown, but the present invention is not limited to monochrome / color, reflective type / transmissive type / semitransmissive reflective type. , Applicable. That is, the color filter does not necessarily have to be provided as in the above-described embodiment, and for example, in the above-described first embodiment, the first electrode used as the reflective layer transmits the light from the backlight. A semi-transmissive reflection type liquid crystal display device may be formed by forming a hole for this.

Further, in the above-mentioned embodiment, the structure in which the surface formed by the liquid crystal side surface of the electrode and the liquid crystal side surface of the insulating film is substantially flat is taken as an example, but the present invention is not limited to this structure.
If the step between the liquid crystal side surface of the electrode and the liquid crystal side surface of the insulating film is smaller than the film thickness of one or both of the first electrode and the second electrode, the disorder of the alignment direction of the liquid crystal molecules is improved. Thus, the effect of improving the orientation of the liquid crystal can be obtained.

Further, in the above-mentioned embodiment, the structure in which the liquid crystal has a positive dielectric anisotropy has been taken as an example, but the present invention is not limited to this structure, and a structure in which the liquid crystal has a negative dielectric anisotropy is also possible. Good.
Further, in the above embodiment, the configuration in which the first electrode and the pixel switching TFT are electrically connected has been taken as an example, but the configuration is not limited to this, and the second electrode and the pixel switching TFT are not limited to this. It may be configured to be electrically connected.

Further, in the above embodiment, the structure in which the first electrode also serves as the reflective layer has been described as an example of the reflective type, but the invention is not limited to this structure and the reflective layer (reflective plate) is provided separately from the first electrode. May be provided. Further, as the electrode configuration of the FFS system, not only the configuration in which the second electrode is laminated on the first electrode via the insulating film, but also the configuration in which the inter-electrode distance is made smaller than the cell gap by using the same layer configuration as the IPS May be adopted.

Further, regarding the concrete description of the shape, dimensions, etc. of each component such as the first electrode and the second electrode, the data line, the gate line, etc., it is not limited to the example of the above embodiment,
The design can be changed as appropriate.

[0073]

EXAMPLES The effects of the liquid crystal display device of the present invention will be described in detail below with reference to examples. The liquid crystal display device of the present invention shown in FIG. 2 and the liquid crystal display device of the present invention shown in FIG. 2 and a conventional liquid crystal display device which are different only in that an insulating film is not provided are prepared and a voltage is applied. The distribution of transmittance in the direction crossing the electrode fingers of the liquid crystal display device was measured to examine the alignment state of liquid crystal molecules.

The results are shown in FIG. FIG. 13 is a graph showing the distribution of the transmissivity in the direction crossing the electrode fingers of the liquid crystal display device when a voltage is applied, where the vertical axis represents the transmissivity and the horizontal axis represents the electrode fingers 6a in the liquid crystal display device. The relative position in the transverse direction is shown. In FIG. 13, the lower part of the horizontal axis is aligned with the relative position of the horizontal axis,
3 is a cross-sectional view of an electrode finger 6a and an insulating film 17 that form a second electrode 6 of the liquid crystal display device shown in FIG. Also,
In FIG. 13, symbol b indicates the transmittance of the liquid crystal display device of the present invention, and symbol a indicates the transmittance of the conventional liquid crystal display device.

From FIG. 13, in the liquid crystal display device of the present invention,
The transmittance on the second electrode 6 is higher than that of the conventional liquid crystal display device in which the insulating film is not provided. From this, it can be seen that the liquid crystal molecules located on the second electrode 6 are driven in a good alignment state, and the disorder in the alignment direction of the liquid crystal molecules is improved. Therefore, according to the liquid crystal display device of the present invention, it was confirmed that bright white display was obtained in the voltage applied state.

[0076]

As described above in detail, in the liquid crystal display device of the present invention, the insulating film is embedded between the electrode fingers, and the step between the upper surface of the second electrode and the upper surface of the insulating film is reduced. Since the thickness is smaller than the film thickness of the second electrode, the disorder of the alignment direction of the liquid crystal molecules is improved, and the alignment property of the liquid crystal can be improved. Further, in the liquid crystal display device of the present invention, an insulating film is embedded between the adjacent first and second electrodes, and a step between the upper surfaces of the first and second electrodes and the upper surface of the insulating film is The thickness may be smaller than the film thickness of either or both of the first electrode and the second electrode. This configuration also improves the disorder of the alignment direction of the liquid crystal molecules and improves the alignment property of the liquid crystal. Is possible. Therefore, according to the liquid crystal display device of the present invention, a liquid crystal display device that is bright and has excellent display quality can be realized.

[Brief description of drawings]

FIG. 1 is a plan view showing a configuration of a lower substrate in a liquid crystal display device of a first embodiment.

FIG. 2 is an enlarged cross-sectional view of a part of the liquid crystal display device of the first embodiment.

3A and 3B are diagrams showing a state of liquid crystal molecules in a state in which no voltage is applied, together with a second electrode and an insulating film, FIG. 3A is a plan view, and FIG. 3B is a sectional view.

4A and 4B are diagrams showing a state of liquid crystal molecules under a voltage applied state together with a second electrode and an insulating film, FIG. 4A is a plan view, and FIG. 4B is a sectional view.

5 is a diagram for explaining a part of an example of a method for manufacturing a liquid crystal display device of the present invention, which is a cross-sectional view showing a portion corresponding to the liquid crystal display device shown in FIG.

6 is a diagram for explaining a part of the example of the method for manufacturing the liquid crystal display device of the present invention, which is a cross-sectional view showing a portion corresponding to the liquid crystal display device shown in FIG.

FIG. 7 is a view for explaining a part of another example of the method for manufacturing the liquid crystal display device of the present invention, which is a cross-sectional view showing a portion corresponding to the liquid crystal display device shown in FIG. is there.

FIG. 8 is an enlarged cross-sectional view of a part of the liquid crystal display device of the present embodiment.

FIG. 9 is a diagram showing an example of an electronic apparatus including the liquid crystal display device of the present invention.

FIG. 10 is a diagram showing another example of an electronic device including the liquid crystal display device of the present invention.

FIG. 11 is a diagram showing another example of an electronic apparatus including the liquid crystal display device of the present invention.

FIG. 12 is a lateral electric field mode liquid crystal display device ((a) IP).
It is a figure for demonstrating the principle of S system and (b) FFS system).

FIG. 13 is a graph showing a distribution of transmissivity in a direction crossing the electrode fingers of the liquid crystal display device in a voltage applied state, in which the vertical axis represents the transmissivity and the horizontal axis represents the electrode fingers 6a in the liquid crystal display device. The relative position in the transverse direction is shown.

[Explanation of symbols]

1 Lower substrate 5 TFT 6, 31 Second electrode 6a, 31a, 32a electrode fingers 6b conductive layer 7 Upper substrate 13, 27 Transparent substrate 14, 32 First electrode 15, 15a, 15b, 17a Insulating layer 16, 21 Alignment film 17,37 Insulation film 18 color filters 22 Liquid crystal 23 Liquid crystal molecules

Claims (12)

[Claims] 1. A liquid crystal display device in which a liquid crystal is sandwiched between a pair of substrates facing each other, wherein an electrode and a switching element are provided on one of the pair of substrates, Is composed of a first electrode and a second electrode having a plurality of electrode fingers formed above the first electrode via an interlayer insulating layer, and the switching element is the first electrode or the first electrode. Two
Electrically connected to one of the electrodes, the liquid crystal is driven by a lateral electric field generated by the first electrode and the second electrode, an insulating film is embedded between the electrode fingers, A liquid crystal display device, wherein a step between the upper surface of the second electrode and the upper surface of the insulating film is smaller than the film thickness of the second electrode. 2. The liquid crystal display device according to claim 1, wherein a surface formed by the upper surface of the second electrode and the upper surface of the insulating film is substantially flat. 3. The liquid crystal display device according to claim 1, wherein the first electrode is provided on the entire surface of the one substrate. 4. The first electrode and the second electrode each have a plurality of electrode fingers, and the electrode fingers of the second electrode are arranged at a position between the electrode fingers of the first electrode in plan view. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is provided. 5. A liquid crystal display device in which liquid crystal is sandwiched between a pair of substrates facing each other, wherein an electrode and a switching element are provided on one of the pair of substrates, and the electrode Comprises a first electrode and a second electrode provided in the same layer as the first electrode, wherein the first electrode and the second electrode have a plurality of electrode fingers, and the electrode of the second electrode The finger is disposed at a position between the electrode fingers of the first electrode, and the switching element is the first electrode or the second electrode.
The liquid crystal is electrically connected to one of the electrodes, and the liquid crystal is driven by a horizontal electric field generated between the first electrode and the second electrode, and is driven between the adjacent first electrode and second electrode. Is filled with an insulating film, and a step between the upper surfaces of the first electrode and the second electrode and the upper surface of the insulating film is smaller than the film thickness of the first electrode and the second electrode. Liquid crystal display device. 6. The liquid crystal display device according to claim 5, wherein a surface formed by the upper surfaces of the first electrode and the second electrode and the upper surface of the insulating film is substantially flat. 7. The liquid crystal display device according to claim 1, wherein the liquid crystal has a positive dielectric anisotropy. 8. Claims 1 to 4 or claim 7.
The manufacturing method for manufacturing the liquid crystal display device according to any one of 1, wherein a step of forming a first electrode on one of the pair of substrates, and a step of forming a first electrode above the first electrode. Forming a second electrode having a plurality of electrode fingers via an interlayer insulating layer; forming an insulating layer on the entire surface of the second electrode; and insulating the surface of the second electrode until exposed. And a step of forming an insulating film between the electrode fingers by polishing the layer, the method for manufacturing a liquid crystal display device. 9. Claims 1 to 4 or claim 7.
The manufacturing method for manufacturing the liquid crystal display device according to any one of 1, wherein a step of forming a first electrode on one of the pair of substrates, and a step of forming a first electrode above the first electrode. Forming an insulating layer and removing a part of the insulating layer in the thickness direction to form a comb-shaped recess in a plan view on the surface of the insulating layer; and forming a conductive layer on the surface of the insulating layer. Then, by polishing the conductive layer until the surface of the insulating layer is exposed, a second electrode having a plurality of electrode fingers is formed, and
A step of forming an insulating film between the electrode fingers, the method of manufacturing a liquid crystal display device. 10. A substrate is provided with an electrode and a switching element, and the electrode has a first electrode and a plurality of electrode fingers formed above the first electrode via an interlayer insulating layer. A second electrode, wherein the switching element is the first electrode or the second electrode.
An insulating film is electrically connected to either one of the electrodes, an insulating film is embedded between the electrode fingers, and a step between the upper surface of the second electrode and the upper surface of the insulating film is a film thickness of the second electrode. A substrate for a liquid crystal display device, which is smaller than 11. An electrode and a switching element are provided on a substrate, and the electrode comprises a first electrode and a second electrode provided in the same layer as the first electrode, the first electrode and the first electrode. The two electrodes have a plurality of electrode fingers, the electrode fingers of the second electrode are arranged at positions between the electrode fingers of the first electrode, and the switching element is the first electrode or the second electrode.
An insulating film is electrically connected to one of the electrodes, and an insulating film is embedded between the first electrode and the second electrode which are adjacent to each other, and upper surfaces of the first electrode and the second electrode and the insulating film. The step for the liquid crystal display device is smaller than the film thickness of one or both of the first electrode and the second electrode. 12. An electronic apparatus comprising the liquid crystal display device according to claim 1. Description: