JP3199221B2 - Liquid crystal display device and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a liquid crystal display device capable of realizing highly bright display or reducing power consumption by extending a display electrode in the first direction in a display area, extending counter electrodes and a source signal wiring in the first direction, and shraddling them over display areas. SOLUTION: A plurality of display areas 2a put with display electrodes 2 and counter wirings 1 between are provide in a matrix state in an active matrix substrate 100. A gate signal wiring 3 and a source signal wiring 4 are provided through the circumference of a display area 2. The counter wiring 1 is formed in a stripe state on a insulation film between layers, and the counter wiring 1 and display electrode 2 are arranged so as to be made in parallel to each other in the longitudinal direction. The counter wiring 1 forms the peripheral part of a display area 2a, and arranged at the position where it is not superimpose with be adjacent source signal wiring 4. Further, the counter wiring 1 forms a extended stripe shape while straddling adjacent plural display areas 2a in the longitudinal direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device having a switching element such as a thin film transistor (hereinafter, referred to as TFT) and using a liquid crystal or the like as a display medium, and more particularly to a structure of an active matrix substrate.

[0002]

2. Description of the Related Art An active matrix type liquid crystal display device in which TFTs are formed in a matrix on an insulating substrate such as glass and used as switching elements is expected to realize a flat panel display with high image quality. I have. As an effective means for realizing a wide viewing angle in a conventional active matrix type liquid crystal display device, a method of applying an electric field to a liquid crystal in a direction substantially parallel to a substrate has been proposed (for example, Japanese Patent Application Laid-Open No. 7-36058). No.).

FIGS. 11 (a), 11 (b) and 12 show such a conventional active matrix type liquid crystal display device 40. FIG.
0 is shown. 11A and 11B show a portion corresponding to one pixel on the active matrix substrate 401, and FIG. 12 shows a line A shown in FIG.
-A 'active-matrix liquid crystal display device 4
00 shows a cross section.

As shown in FIG. 12, an active matrix type liquid crystal display device 400 includes an active matrix substrate 401, a counter substrate 402, and a liquid crystal layer 17 sandwiched between both substrates. The active matrix substrate 401 includes a glass substrate 100, a gate signal line 102, a common wiring 123, a gate insulating film 103, a source signal line 108, and a semiconductor layer 10 formed on the glass substrate 100.
4, a pixel electrode 111 and a drive electrode 113. The gate insulating film 103 is formed so as to cover the gate signal wiring 102 and the common wiring 123, and the semiconductor layer 104, the source signal wiring 108, the pixel electrode 111,
And a drive electrode 113 are formed.

As shown in FIGS. 11A and 11B, a source signal line 108 has a branch 108 'at a portion where the source signal line 108 intersects with the gate signal line 102, and the gate signal line 108 has a branch 108'. A switching element (TFT) 403 is configured by using 102 as a gate electrode 105, a branch portion 108 'as a source electrode, and a picture element electrode 111 as a drain electrode. The drive electrode 113 is formed from the same material as the pixel electrode 111. The drive electrode 13 is a through-hole 2
00 is connected to the common wiring 123.

[0006] A protective insulating film 124 is formed so as to cover the source signal line 108, the picture element electrode 111, the driving electrode 113, and the switching element 403.
16 are formed. The common wiring 23 and the pixel electrode 11 intersect via the gate insulating film 3, and an additional capacitance is formed at the intersection.

The opposing substrate 402 includes a substrate 114 and a substrate 1
14 is provided with the alignment film 116 formed on the active matrix substrate 401 side and the deflection plate 112 formed on the outside.

In such an active matrix type liquid crystal display device 400, the liquid crystal layer 117 is driven by an electric field formed in a direction substantially parallel to the substrate surface (lateral electric field driving system). As shown in FIG. 11A, when no voltage is applied, the liquid crystal molecules 25
It is oriented so as to have a slight angle (0 degree or more and less than 15 degrees) with respect to the longitudinal direction of 1 and the drive electrode 113. When a voltage is applied between the pixel electrode 111 and the drive electrode 113, the liquid crystal molecules 25 are oriented along the electric field E from the pixel electrode 111 to the drive electrode 113, as shown in FIG.

[0009]

In the above-described liquid crystal display device 400 of the lateral electric field driving system, the common wiring 1
23 and its drive electrode 113 are arranged on the TFT substrate side, so that the common wiring (drive electrode) is disposed on the active matrix substrate side as compared with the conventional vertical electric field drive type liquid crystal display device in which the common electrode (drive electrode) is arranged on the counter substrate side. The electrode wiring structure becomes complicated. Therefore, there is a problem in that crosstalk due to parasitic capacitance between the respective wirings is likely to occur. Further, in the case of a transmissive type other liquid crystal display device, a sufficient luminance cannot be obtained because the area of the opening through which the backlight is transmitted is reduced due to the presence of the common wiring and the drive electrode.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object the following objects: (1) By increasing the area of an opening through which backlight light is transmitted, a high-luminance display or Provided is a liquid crystal display device that can realize low power consumption, and (2) a liquid crystal display device that realizes high-quality display with reduced crosstalk by suppressing the influence of source signal lines on picture element electrodes. It is in.

[0011]

A liquid crystal display device according to the present invention comprises: a substrate; a gate signal line and a gate insulating film provided on the substrate; a source signal line provided on the gate insulating film; A thin film transistor formed at each intersection of the gate signal line and the source signal line; a drain electrode connected to the thin film transistor; a connection electrode connected to the drain electrode; a portion of the connection electrode; A common wiring for forming a storage capacitor via the gate insulating film, an interlayer insulating film formed on the gate insulating film, a display electrode and a counter electrode for driving a liquid crystal provided on the interlayer insulating film, A liquid crystal display comprising: an active matrix substrate having: a counter substrate facing the active matrix substrate; and a liquid crystal layer sandwiched between the active matrix substrate and the counter substrate. An apparatus, the display electrodes extend in a first direction in the display region, the counter electrode and the source signal lines extending in the first direction of the display area,
In addition, the display area extends over a plurality of display areas, thereby achieving the above object.

In one embodiment, at least one of the display electrode and the counter electrode is formed so as to overlap the source signal wiring.

In another embodiment, at least one of the display electrode and the counter electrode is formed so as to overlap the gate signal wiring.

According to the liquid crystal display device of the present invention, a substrate, a gate signal wiring and a gate insulating film provided on the substrate,
And the source signal line provided on said gate insulating film, 該Ge
A thin film transistor formed at each intersection between the over preparative signal lines and the source signal line, a drain electrode connected to the thin film transistor, and a connecting electrode connected to the drain electrode, a portion said of said connection electrode A common wiring for forming a storage capacitor via the gate insulating film, an interlayer insulating film formed on the gate insulating film, a display electrode and a counter electrode for driving a liquid crystal provided on the interlayer insulating film, A liquid crystal display device comprising: an active matrix substrate having: a counter substrate facing the active matrix substrate; and a liquid crystal layer sandwiched between the active matrix substrate and the counter substrate. The common wiring is directly connected to the common insulating layer via a contact hole provided in the interlayer insulating layer, thereby achieving the above object.

According to the liquid crystal display device of the present invention, a substrate, a gate signal line and a gate insulating film provided on the substrate,
And the source signal line provided on said gate insulating film, 該Ge
A thin film transistor formed at each intersection between the over preparative signal lines and the source signal line, a drain electrode connected to the thin film transistor, and a connecting electrode connected to the drain electrode, a portion said of said connection electrode An active having a common wiring for forming a storage capacitor via a gate insulating film, an interlayer insulating film formed on the gate insulating film, and a liquid crystal driving display electrode provided on the interlayer insulating film. A matrix substrate, and a liquid crystal facing the active matrix substrate.
A counter substrate having a driving counter electrode substantially at the center of the display area is provided, and the active matrix substrate and a liquid crystal layer sandwiched between the counter substrates are provided, thereby achieving the above object.

In one embodiment, the display electrode is formed so as to overlap with the source signal wiring or the gate signal wiring.

In another embodiment, the longitudinal direction of the counter electrode has a fixed angle with respect to the longitudinal direction of the display electrode.

In still another embodiment, the interlayer insulating layer has a thickness of 1.0 to 10.0 μm.

Further, in another embodiment, the value of the dielectric constant of the interlayer insulating layer is 1.5 to 3.5. Further, in another embodiment, the material of the interlayer insulating film is an organic resin.

Further, in another embodiment, an image is displayed by rotating the liquid crystal layer molecules in the display area in a direction substantially horizontal to the substrate surface.

According to a method of manufacturing a liquid crystal display device according to the present invention, a gate electrode is formed on a substrate and a connection electrode is formed.
Forming a common wiring for forming a storage capacitor with the gate insulating layer interposed therebetween; forming a gate insulating layer on the substrate so as to cover the gate electrode and the common wiring; Forming a source signal wiring and a connection electrode on a layer; forming a thin film transistor at an intersection of the gate signal wiring and the source signal wiring; and forming the thin film transistor and the connection on the gate insulating layer. Covers the electrode, the source signal line, and the gate signal line
Forming an interlayer insulating film, and forming a liquid crystal drive display electrode and a counter electrode on the interlayer insulating film,
Connecting the display electrode and the drain electrode connected to the thin film transistor via the connection electrode through a contact hole penetrating a part of the interlayer insulating film, thereby achieving the above object. Is achieved.

According to the method of manufacturing a liquid crystal display device of the present invention, a gate electrode is formed on a substrate and a connection electrode is formed.
Forming a common wiring for forming a storage capacitor with the gate insulating layer interposed therebetween; forming a gate insulating layer on the substrate so as to cover the gate electrode and the common wiring; Forming a source signal wiring and a connection electrode on a layer; forming a thin film transistor at an intersection of the gate signal wiring and the source signal wiring; and forming the thin film transistor and the connection on the gate insulating layer. Covers the electrode, the source signal line, and the gate signal line
Forming an interlayer insulating film as a step of forming a display electrode for driving liquid crystal on the interlayer insulating film, through the connection electrode via a contact hole which penetrates a portion of the interlayer insulating film, the thin film transistor Connecting the drain electrode connected to the display electrode to the display electrode, and forming a counter electrode facing the display electrode through the liquid crystal layer at a substantially central portion of the display region. As a result, the above object is achieved.

According to the present invention, the following effects can be obtained by the above configuration.

1. The display electrode 2 is formed so as to overlap with the adjacent source signal wiring 4 via the interlayer insulating film 9, thereby preventing transmission light from being blocked by the wiring.

2. Since the relative dielectric constant is small, and the gate signal wiring 3, the source signal wiring 4, and the common wiring 25 in the lower layer are insulated by the thick interlayer insulating film 9, generation of stray capacitance is suppressed.

3. By forming the display electrode 2 and the counter wiring 1 using the same material and the same mask, the distance between the two electrodes is accurately formed.

4. By arranging the counter wiring 1 in a stripe shape on the counter substrate 27 side, it is possible to prevent the occurrence of a parasitic capacitance generated between the counter wiring 1 and the peripheral wiring.

5. The counter wiring 1 is arranged on the counter substrate 27 side in the form of a stripe, and with respect to the longitudinal direction of the display electrode 2,
The longitudinal direction of the opposing wiring 1 is given a certain angle, and the electric field intensity generated between the display electrode 2 and the opposing wiring 1 is made different depending on the position in one display area 2a.

6. By directly connecting the counter wiring 1 to the common wiring 25, the connection wiring 6 connected to the TFT is eliminated.

[7] By disposing the opposing wiring 1 at an intermediate position between the two display electrodes 2 sandwiching the opposing wiring 1, the occurrence of a parasitic capacitance between the opposing wiring 1 and the display electrode 2 is prevented.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) FIG. 1 is a plan view showing a configuration of one pixel portion of an active matrix substrate in a transmission type liquid crystal display device according to Embodiment 1 of the present invention. FIGS. 2 and 3 are cross-sectional views taken along lines BB 'and AA' shown in FIG. 1, respectively.

As shown in FIG. 1, the active matrix substrate 100 is provided with a plurality of display areas 2a sandwiched between display electrodes 2 and counter wirings 1 in a matrix. Further, a gate signal line 3 as a scanning line and a source signal line 4 as a signal line are provided so as to pass through the periphery of the display region 2a and to be orthogonal to each other.
Note that, of these signal wirings, a part of the gate signal wiring 3 overlaps with a part of the counter wiring 1 described above. A thin film transistor (hereinafter, referred to as a TFT 22) functioning as a switching element is provided at an intersection of the gate signal line 3 and the source signal line 4, and the TFT 2
The second drain electrode 12 is finally connected to the display electrode 2 via the connection electrode 6a. The gate signal line 3 is connected to the gate electrode 5 of the TFT 22, and the driving of the TFT 22 is controlled by a signal input to the gate electrode 5. The source signal wiring 4 is connected to the source electrode 11 of the TFT 22, whereby a data signal is input to the source electrode 11 of the TFT 22. Where TFT
The drain electrode 12 is connected to the display electrode 2 via the contact electrode 7 via the contact hole 7. Further, as shown in FIG. 3, the connection wiring 6a and the common wiring 25a
Are sandwiched between the gate insulating films 15 as electrodes to form additional capacitance.

Hereinafter, the structure of the liquid crystal display device according to the first embodiment will be described in more detail with reference to FIGS.

First, for the TFT 22 shown in FIG. 2, a gate electrode 5 connected to the gate signal wiring 3 shown in FIG. 1 and a gate insulating film 15 covering the gate electrode 5 are provided on a lower transparent insulating substrate 20. Have been. A semiconductor layer 14 is formed on the gate insulating film so as to overlap with the gate electrode 5,
The channel protection layer 13 is provided at the center of the semiconductor layer 14. Both ends of channel protection layer 13 and semiconductor layer 1
4 are partially separated on the channel protective layer 13 and serve as the source electrode 11 and the drain electrode 12.
A + -a-Si layer is provided. The gate signal line 3 and the common line 25 may be made of a conductive material, for example, ITO, Ti, Cr, Mo, Ta, Al, SnO ₂ , and a conductive resin. Further, not only a single layer structure but also a multilayer structure may be used.
a / Al, Ta / TaN, Ta ₂ O ₅ / Ta / Al and the like are used. The notation method of Ta / Al is A
1 shows a film having a laminated structure in which Ta is formed on 1.

Next, the transparent conductive film 10a and the metal layer 8 are formed on the end of the source electrode 11 which is one n + -a-Si layer.
b is provided to form the source signal wiring 4 having a two-layer structure. Further, on the other end of the drain electrode 12 which is the n + -a-Si layer, the transparent conductive film 10a '
b ′ are provided. The transparent conductive film 10a 'is extended and serves to connect the drain electrode 12 and the display electrode 2, and is integrated with the connection electrode 6 connected to one electrode 6a of the additional capacitor. Furthermore, TFT2
2, an interlayer insulating film 9 is provided so as to cover the gate signal wiring 3, the source signal wiring 4, and the connection electrode 6. Although the metal layer 8b 'and the drain electrode 12 are shown as not contacting in FIG. 2, there is no problem in characteristics even if they are in direct contact. Further, the metal films 8b and 8b '
Are formed at the same time, and these may be conductive materials, such as ITO, Ti, Cr, Mo, Ta, Al, and SnO.
₂ , conductive resin, Ta / TaN, Ta / ITO, T
It may be formed in a laminated structure such as a / TaN / ITO.

As shown in FIG. 3, the display electrodes 2 for forming pixels are provided on the interlayer insulating film 9 so as to face each other. The display electrode 2 is connected to the drain electrode 12 of the TFT 22 via a transparent conductive film 10 a ′ integrated with the connection electrode 6 by a contact hole 7 penetrating the interlayer insulating film 9. Here, the display electrode 2
It is arranged on the periphery of the display area 2a so as to overlap with the source signal wiring 4 via the interlayer insulating film 9. Note that the connection wiring 6 and the transparent conductive films 10a and 10a '
Made of O, SnO ₂ .

On the interlayer insulating film 9, the counter wiring 1 is formed in a stripe shape. The counter wiring 1 and the display electrode 2 are arranged so as to be parallel to each other in the longitudinal direction. The opposing wiring 1 is arranged at a peripheral portion of the display area 2a and at a position that does not overlap with the adjacent source signal wiring 4. Further, the counter wiring 1 has a stripe shape extending over a plurality of display areas 2a adjacent to each other in the longitudinal direction. The counter wiring 1 and the display electrode 2 are formed in the same process, and these materials may be any conductive materials, such as ITO, Ti, Cr, Mo, Ta,
A conductive resin other than Al and SnO ₂ may be used. Also, T
A laminated structure such as a / TaN may be used.

The interlayer insulating film 9 is made of a colorless and transparent material having a sufficiently low relative permittivity and capable of forming a thick film.
Any insulating material may be used. In the first embodiment, the interlayer insulating film 9 is formed using a photosensitive acrylic resin, but a photosensitive resin other than an acrylic resin may be used. Further, a thermosetting resin such as a polyimide resin or an epoxy resin may be used. However, the use of a photosensitive resin is preferable because the productivity is high, the acrylic resin is colorless and transparent, and the relative dielectric constant is low.

Next, the active matrix substrate of the present embodiment as described above can be manufactured as follows.

First, a gate electrode 5, a gate insulating film 15, a semiconductor layer 14, a channel protection layer 13, a source electrode 11 and a drain electrode 12 are formed on a lower transparent insulating substrate 20 such as a glass substrate. An Si layer is sequentially formed. Here, the semiconductor material is not limited to a-Si (amorphous silicon), but may be p-Si (polysilicon), microcrystalline silicon, or a conductive polymer material. The semiconductor layer 14 is formed of an intrinsic semiconductor layer, and the drain electrode and the source electrode are formed of an n + semiconductor layer. The channel protective film 13 and the gate insulating film 15, Chitsuka silicon (Si _x N _y), it is formed by the SiO ₂ and the insulating resin or the like.

The manufacturing process up to this point can be performed in the same manner as the conventional method of manufacturing an active matrix substrate.

Next, the source signal wiring 4 and the connection electrode 6
Transparent conductive films 10a, 10a 'and metal layer 8 constituting
b, 8b ', a film is sequentially formed by a sputtering method, and is patterned into a predetermined shape.

Further, a photosensitive acrylic resin as an interlayer insulating film 9 is further formed thereon by, for example, 5 μm by spin coating.
m.

Next, the resin is exposed according to a desired pattern and developed with an alkaline solution. As a result, only the exposed portions are etched by the alkaline solution, and the contact holes 7 penetrating through the interlayer insulating film 9 are formed.

Thereafter, in order to form the display electrode 2 and the counter wiring 1 constituting the display area 2a, a metal film is formed by a sputtering method, and is simultaneously patterned by etching. As a result, the display electrode 2, which is one of the electrodes constituting the display region 2a, is connected to the transparent conductive film 10a 'connected to the drain electrode 12 of the TFT 22 via the contact hole 7 penetrating the interlayer insulating film 9. Will be. The counter wiring 1 is patterned into a stripe shape. Note that the display electrode 2 and the counter electrode 1 are formed in the same process and with the same material. As described above, the material was formed of a conductive Ta metal film having no light transmission property.
i, Al, Cr, Mo, or a transparent conductive film such as a light-transmissive ITO film. Here, an example using the wet etching technique has been described, but a dry etching technique may be used.

Next, the unit pixel (display region 2
An alignment film 16 made of polyimide was formed on the surface of an active matrix substrate in which a) was arranged in a matrix, and the surface was subjected to a rubbing treatment. Similarly, a counter substrate 27 having a rubbed alignment film 17 formed on its surface.
And a liquid crystal composition in which rod-like liquid crystal molecules 23 are filled between the active matrix substrates, and polarizing plates 18 and 19 are arranged on the outer surfaces of the two substrates. When there is no electric field (FIG. 1A), the liquid crystal molecules 23 have a slight angle with respect to the longitudinal direction of the stripe-shaped display electrode 2 and the counter wiring 1, that is, the relationship between the long axis (optical axis) of the liquid crystal molecules and the electric field. It is oriented so as to have an angle of 45 ° or more and less than 90 ° in a direction (perpendicular to the longitudinal direction of the display electrode 2 and the counter wiring 1). The orientation of the liquid crystal molecules at the interface between the upper and lower substrates was parallel to each other. The dielectric anisotropy of the liquid crystal molecules is positive. Here, when a voltage is applied to the gate electrode 5 of the TFT to turn on the TFT, the display electrode 2 is turned on.
When an electric field E is induced between the display electrode 2 and the opposing wiring 1, a liquid crystal molecule changes its direction in the direction of the electric field as shown in FIG . 2 arranged on the upper and lower substrates
By arranging the polarization transmission axes of the polarizing plates 18 and 19 at a predetermined angle (for example, crossed Nicols where the polarization transmission axes are perpendicular to each other), it becomes possible to change the light transmittance by applying an electric field. As described above, according to the display method of the present invention, it is possible to provide a display which provides a contrast even without the transparent electrode which is conventionally required on the counter substrate 27. For this reason, all of the steps relating to the formation of the transparent electrode can be omitted, so that the manufacturing cost can be reduced. Further, in the conventional display method using a transparent electrode for the opposite substrate, a dark state is obtained by raising the major axis of liquid crystal molecules from the substrate interface by applying a voltage and setting the birefringence phase difference to 0. The viewing angle direction in which the phase difference is 0 is only the front, that is, the direction perpendicular to the substrate interface,
Even if it is slightly tilted, a birefringence phase difference appears, and in a normally white type display, light leaks, causing a decrease in contrast and a reversal of gradation levels. However, in the display method of this embodiment, the major axis of the liquid crystal molecules is substantially parallel to the substrate and does not rise even when a voltage is applied. Therefore, the change in brightness when the viewing angle direction is changed is small, and the viewing angle characteristics are greatly improved.

In the active matrix substrate thus obtained, an interlayer insulating film 9 is formed between the gate signal wiring 3, the source signal wiring 4, the TFT 22, and the liquid crystal display electrode 2 and the counter wiring 1. Therefore, the display electrode 2 and the counter wiring 1 can be formed so as to overlap each of the wirings 3 and 4 and the TFT 22, and the surface thereof can be flattened.

For example, as shown in FIG. 2, the display electrode 2 is overlapped on the source bus line connected to the TFT for supplying the data signal via the interlayer insulating film 9, while the opposite electrode 1
Are arranged so as to form a pair across the display area 2a and not to overlap with the adjacent source signal lines 4,
The transmission area of the backlight can be enlarged.

Therefore, when a transmissive liquid crystal display device having a liquid crystal interposed between an active matrix substrate and a counter substrate is configured, the aperture ratio can be improved, and the electric field caused by the wirings 3 and 4 can be improved. Is shielded by the display electrode 2 forming the display region 2a and the opposing wiring 2 so that poor alignment of the liquid crystal can be suppressed.
4 and liquid crystal alignment failure due to steps caused by the TFT 22 can be suppressed.

The acrylic resin forming the interlayer insulating film 9 has a relative dielectric constant of 1.5 to 3.5, which is lower than that of the inorganic film (the relative dielectric constant of silicon nitride is 8). Since the thickness can be easily increased to 1.0 to 10.0 μm, the capacitance between the gate signal line 3 and the display electrode 2 can be reduced. As a result, sag and distortion of the signal waveform can be reduced. Similarly,
The capacitance between each of the wirings 3 and 4 and the display electrode 2 and the counter wiring 1 can be reduced, so that sag and distortion of the signal waveform can be reduced. Therefore, each wiring 3,
The influence of crosstalk and the like on the display caused by the capacitance component between the display electrode 4 and the display electrode 2 and the counter wiring 1 can be further improved, and a good and bright display can be obtained.
In addition, by performing patterning by exposure and alkali development, the tapered shape of the contact hole 7 can be improved, so that a good connection between the display electrode 2 and the transparent conductive film 10a 'forming the connection electrode 6 can be achieved. Will be able to gain. In addition, since a photoresist process is not required for the patterning, it is advantageous from the viewpoint of improving productivity. Here, the acrylic resin used as the interlayer insulating film 9 is colored before coating, but can be made more transparent by performing an overall exposure process after patterning. It should be noted that such a transparent treatment of the resin is not limited to being performed by an optical treatment, but may be performed by a chemical treatment. In addition, an acrylic resin is also a preferable material from the viewpoint of high transparency.

(Embodiment 2) It has been considered that when the counter electrode 1 and the display electrode 2 are formed on the interlayer insulating film 9, it is difficult to obtain good display characteristics due to an increase in stray capacitance. However, as described above, the interlayer insulating film 9 used in the liquid crystal display device of the present invention has a feature that the dielectric constant is extremely low and the layer thickness can be increased. Even if a configuration is adopted in which it is disposed so as to overlap with the source signal wiring 4 via the film 9, the stray capacitance can be extremely reduced. Therefore, the effect brought about by overlapping the counter electrode 1 and the source signal wiring 4 via the interlayer insulating film 9 can improve the aperture ratio and the contrast of the liquid crystal display device. With the same effect, the display electrode 2
Is arranged so as to overlap with the gate signal wiring 3 via the interlayer insulating film 9, the generation of stray capacitance can be minimized, thereby improving the aperture ratio and contrast. To

In the lateral electric field mode, the interlayer insulating film
Are planarized by, since the reverse tilt does not occur in the liquid crystal display device according to the invention, essentially black mask is not required. However, as in the first and second embodiments, the counter wiring 1 in the display area 2a is not used.
In the case where the distance between the display electrode 2 and the display electrode 2 is different,
There is a concern that a problem of poor orientation based on a change in response speed due to a difference in distance between the two may occur. Therefore, a black mask may be provided between the opposing wiring 1 and the display electrode 2 which are close to each other and in which the occurrence of an alignment defect may be caused.

(Embodiment 3) FIG. 4 is a plan view showing a liquid crystal display device according to Embodiment 3 of the present invention. 5 and 6 are cross-sectional views taken along lines BB 'and AA' shown in FIG. 3, respectively. In Embodiment 3, Embodiments 1 and 2
The difference from the first embodiment is that the position of the opposing wiring 1 is arranged substantially at the center of the display area 2a, and that the opposing wiring 1 is arranged on the opposing substrate side.

That is, as can be seen from FIGS. 4 to 6, the liquid crystal driving display electrode 2 is provided on the active matrix substrate, and this point has the same configuration as the first and second embodiments. On the other hand, on the counter substrate side, the counter wiring 1 is arranged in the center of the display area 2a in a stripe shape, which is a configuration unique to the present embodiment.

The method of manufacturing the liquid crystal display device according to the third embodiment will now be described.
This will be described with reference to FIGS.

The respective manufacturing steps up to the formation of the interlayer insulating film 9 are as follows.
Since the process is the same as that of the first embodiment, the subsequent manufacturing process will be described. An alignment film 16 made of polyimide is formed on a surface of an active matrix substrate 28 in which unit pixels (display areas 2a) are arranged in a matrix,
The surface was rubbed.

Next, a conductive film is formed on the opposite substrate 27 by a vapor deposition method, and is subjected to a photolithography process and an etching process.
A stripe-shaped opposing wiring 1 was formed. Here, Ta was used as the material of the conductive film, but Ti, Al, Cr,
ITO or the like may be used. Subsequently, an alignment film 17 made of polyimide was formed on the surface of the counter substrate 27, and rubbing was performed on the surface.

The counter substrate 27 formed as described above
And a liquid crystal composition in which rod-like liquid crystal molecules 23 were sealed between the active matrix substrates. Furthermore, polarizing plates 18 and 19 were arranged on the surfaces of the active matrix substrate 28 and the counter substrate 27 on the side opposite to the alignment film. When there is no electric field, the liquid crystal molecules 23 have a small angle with respect to the longitudinal direction of the stripe-shaped display electrode 2 and the counter wiring 1, that is, the major axis (optical axis) of the liquid crystal molecules and the direction of the electric field (the display electrode 2 and the counter wiring). 1 (perpendicular to the longitudinal direction). The orientation of the liquid crystal molecules at the interface with the upper and lower substrates was made parallel to each other. The dielectric anisotropy of the liquid crystal molecules is positive. Here, when a voltage is applied to the gate electrode 5 of the TFT to turn on the TFT, a voltage is applied to the display electrode 2, and an electric field E is induced between the display electrode 2 and the counter wiring 1. The direction is changed (FIG. 4A). In FIGS. 5 and 6, since the thickness direction is illustrated in an enlarged manner, the electric field direction E appears to be inclined. However, in an actual liquid crystal display device, the width of the display region 2a ′ is 40 μm. Since the thickness of the liquid crystal layer is about 6 μm, which is about one digit smaller than that of the liquid crystal layer of about 80 μm, the electric field component in the thickness direction of the liquid crystal layer is extremely small, and the electric field direction can be considered to be almost parallel to the substrate surface. In the above configuration, by arranging the polarization transmission axes of the two polarizing plates 18 and 19 disposed on the surfaces of the upper and lower substrates at a predetermined angle (for example, crossed Nicols where the polarization transmission axes are orthogonal to each other), light is applied by electric field application. Can be changed.

As described above, by disposing the opposing wiring 1 substantially at the center of the opposing substrate 27, the stray capacitance can be reduced as compared with the first and second embodiments. Therefore, sag and distortion of the signal waveform caused by the stray capacitance can be more effectively improved. Further, generation of off-current due to parasitic capacitance can be prevented. Furthermore, in the case of a configuration in which the distance between the opposing wiring 1 and the display electrode 2 is different in the display area 2a as in the first and second embodiments, the response speed is changed based on the difference in the distance between the two. Although there is a concern that the problem of poor orientation may occur, in the present embodiment, such a problem does not occur, and it is not necessary to provide the black mask mentioned in the first and second embodiments.

(Embodiment 4) FIG. 7 is a plan view showing a liquid crystal display device according to Embodiment 4 of the present invention. 8 and 9 are cross-sectional views taken along lines BB 'and AA' shown in FIG. 7, respectively. The fourth embodiment is different from the third embodiment in that the opposing wires 1 in the longitudinal direction are arranged at a certain angle with respect to the longitudinal direction of the display electrodes.

That is, as can be seen from FIGS. 7A and 7B, in the configuration in which the counter wiring 1 is arranged on the counter substrate 27 side, the longitudinal direction of the counter wiring 1 is The counter wiring 1 is arranged so as to be formed in a direction having a certain angle, preferably in a direction along a diagonal line of the quadrangular display area 2 a formed by the source signal wiring 4 and the gate signal wiring 3. I have.

Assuming that the display area 2a is a set of a plurality of small areas, the above-described structure allows
As shown in the cross-sectional view, the electric field strength between the display electrode 2 and the opposing wiring 1 changes depending on the position of the minute area in the display area 2a. Therefore, in the micro regions at different positions, the rotation angle of the liquid crystal molecules changes,
This also affects the value of the birefringence phase difference, so that the inclination of the polarization plane of the circularly polarized light propagating through the liquid crystal layer differs. Accordingly, in the liquid crystal layer of the display area 2a, light having different phase differences or polarization planes propagates depending on the position, thereby greatly improving the viewing angle characteristics.

(Embodiment 5) FIG. 10A is a plan view showing a liquid crystal display device according to Embodiment 5 of the present invention.

In FIG. 10A, the common wiring 25 is
It is different from the other embodiments in that it is arranged near the gate signal wiring 3 connected to the TFT 22.

By adopting such a configuration, it is possible to suppress the occurrence of the disorder of the alignment of the liquid crystal molecules in the central portion of the display area 2a. That is, since the alignment disorder region is limited to the peripheral portion of the display region 2a, the display quality is greatly improved in the entire display region. In addition, a higher quality display can also be obtained by covering only the peripheral portion where the orientation is disordered with a black mask.

(Embodiment 6) FIG. 10B is a plan view showing a liquid crystal display device according to Embodiment 6 of the present invention.

According to FIG. 10B, the counter wiring 1 is directly connected to the common wiring 25 via the contact hole 7 provided in the interlayer insulating film 9, and the display electrode 2 is similarly connected to the common wiring 25. It is directly connected to the TFT 22 via the contact hole 7 provided in the film 9.

By employing such a structure, the connection electrode 6 formed of a transparent conductive film in the display region 2a is different from the case where a storage capacitor is formed on the drain electrode side via the interlayer insulating film 9. Need not be disposed, the transmittance of transmitted light is greatly improved, and the contrast and brightness can be improved. According to such a configuration, the problem of data signal delay due to the wiring resistance of the connection wiring 6 can be solved.

(Embodiment 7) FIG. 10C is a plan view showing a liquid crystal display device according to Embodiment 7 of the present invention.

According to FIG. 10C, the counter wiring 1 is directly connected to the common wiring 25 as in the seventh embodiment, and the counter wiring 1 is connected between the liquid crystal driving display electrodes 2 for driving the display area 2a. It is arranged so that it may be located in the middle position.

By adopting such a configuration, it is possible to prevent the occurrence of a parasitic capacitance generated between the display electrode 2 and the counter wiring 1, so that it is possible to suppress the sagging and distortion of the signal waveform. FIG. 10D shows a configuration in which the features of the seventh embodiment and the features of the fifth embodiment are combined.

In the present embodiment, the counter electrode 1 is shown as a band-shaped electrode, but the counter electrode 1 and the display electrode 2 may have a comb shape. That is, the interelectrode distance between the opposing electrode 1 and the display electrode 2 may be constant, and the opposing electrode 1 and the display electrode 2 may be engaged with each other.

The drive signal of the liquid crystal display device of the present invention may be the same drive signal as that of the TN mode liquid crystal display device, and the applied voltage depends on the liquid crystal material and the cell structure (for example, between the display electrode 1 and the counter electrode 2). Distance). Further, the common wiring may have a constant potential. Further, in the liquid crystal display device of the present invention, the additional capacitance is formed between the connection electrode 6a and the common wiring 25a, but the common wiring 25a may not be provided if the voltage can be held by the liquid crystal material. Further, an additional capacitance may be provided by forming an insulating film on the gate signal wiring 3.

[0074]

According to the above embodiment, the following operations and effects can be obtained.

1. Since the display electrode 2 is formed so as to overlap with the adjacent source signal wiring 4 via the interlayer insulating film 9, it is possible to prevent the transmission light from being blocked by the wiring, thereby improving the aperture ratio. To achieve high contrast and high brightness.

2. Since the relative dielectric constant is small, and the gate signal wiring 3, the source signal wiring 4, and the common wiring 25 in the lower layer are insulated by the thick interlayer insulating film 9, generation of stray capacitance is suppressed. As a result, fluctuations in the driving capacity of the liquid crystal can be prevented, and a data signal with little sagging or distortion can be accurately transmitted to the liquid crystal layer, so that high-contrast display is possible.

3. By forming the display electrode 2 and the counter wiring 1 using the same material and the same mask, the distance between the two electrodes can be accurately formed, thereby improving the manufacturing cost and the yield.

4. By arranging the opposing wiring 1 in a stripe shape on the opposing substrate 27 side, it is possible to prevent the occurrence of a parasitic capacitance generated between the opposing wiring 1 and a peripheral wiring, thereby preventing a deterioration in display quality due to a delay of the opposing signal. .

5. The paired wirings 1 are arranged in a stripe shape on the counter substrate 27 side, and are arranged in the longitudinal direction of the display electrode 2.
By giving a certain angle to the longitudinal direction of the opposing wiring 1, the electric field intensity generated between the display electrode 2 and the opposing electrode 1 is made different depending on the position in one display area 2a, thereby displaying a wide viewing angle. Enable.

6. By directly connecting the opposing wiring 1 to the common wiring 25, the connection wiring 6 connected to the TFT is eliminated, so that a data signal delay due to the influence of wiring resistance can be prevented and the transmittance of transmitted light can be improved. .

7. By disposing the opposing wiring 1 at an intermediate position between the two display electrodes 2 sandwiching the opposing wiring 1, it is possible to prevent occurrence of a parasitic capacitance between the opposing wiring 1 and the display electrode 2, thereby suppressing generation of the parasitic capacitance. Thus, generation of off current can be prevented.

[Brief description of the drawings]

FIG. 1 is a plan view illustrating a configuration of a liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is a sectional view of the liquid crystal display device taken along the line B-B 'of FIG.

FIG. 3 is a sectional view of the liquid crystal display device of FIG. 1 taken along line A-A ';

FIG. 4 is a plan view illustrating a liquid crystal display device according to a second embodiment of the present invention.

5 is a cross-sectional view of the liquid crystal display device of FIG. 4, taken along line B-B '.

6 is a cross-sectional view of the liquid crystal display device of FIG. 4 taken along line A-A '.

FIG. 7 is a plan view illustrating a configuration of a liquid crystal display device according to a fifth embodiment of the present invention.

8 is a cross-sectional view of the liquid crystal display device of FIG. 7 taken along line B-B '.

9 is a cross-sectional view of the liquid crystal display device of FIG. 7 taken along line A-A '.

FIG. 10A is a plan view illustrating a configuration of a liquid crystal display device according to a fifth embodiment of the present invention. (B) is a plan view showing the configuration of the liquid crystal display device according to Embodiment 6 of the present invention.
(C) is a plan view showing the configuration of the liquid crystal display device of Embodiment 7 of the present invention. (D) is a top view which shows another structure of the liquid crystal display device of Embodiment 7 of this invention.

FIGS. 11A and 11B are plan views showing a configuration of a conventional liquid crystal display device.

FIG. 12 is a cross-sectional view illustrating a configuration of a conventional liquid crystal display device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Counter wiring 2 Display electrode 2a Display area 2b Display electrode lead-out part 3 Gate signal wiring 4 Source signal wiring 5 Gate electrode 6 Connection electrode 7 Contact hole 8b ', 8b Metal layer 9 Interlayer insulating film 10a, 10a' Transparent conductive film 11 Source Electrode 12 Drain electrode 13 Channel protective layer 14 Semiconductor layer 15 Gate insulating film 16 Lower alignment film 17 Upper alignment film 18, 19 Polarizer 20 Lower transparent insulating substrate 21 Upper transparent insulating substrate 22 TFT 23 Liquid crystal molecules 24 Liquid crystal layer 25 common wiring 27 counter substrate 28 active matrix substrate

Claims (13)

(57) [Claims] A substrate; a gate signal line and a gate insulating film provided on the substrate; a source signal line provided on the gate insulating film; and a gate signal line and the source signal line. A thin film transistor formed at the intersection, a drain electrode connected to the thin film transistor,
A connection electrode connected to the drain electrode, a common wiring for forming a storage capacitor via a part of the connection electrode and the gate insulating film, and an interlayer insulating film formed on the gate insulating film; An active matrix substrate having a liquid crystal driving display electrode and a counter electrode provided on the interlayer insulating film, a counter substrate facing the active matrix substrate, and sandwiched between the active matrix substrate and the counter substrate; And a liquid crystal layer, wherein the display electrode extends in a first direction in the display area, and the counter electrode and the source signal wiring are in the first direction in the display area. elongation, and liquid crystal display devices over a plurality of the display area. 2. The liquid crystal display device according to claim 1, wherein at least one of the display electrode and the counter electrode is formed so as to overlap with the source signal wiring. 3. The liquid crystal display device according to claim 1, wherein at least one of the display electrode and the counter electrode is formed so as to overlap the gate signal line. 4. A substrate, a gate signal wiring and a gate insulating film provided on the substrate, a source signal wiring provided on the gate insulating film, and each of the gate signal wiring and the source signal wiring. A thin film transistor formed at the intersection, a drain electrode connected to the thin film transistor,
A connection electrode connected to the drain electrode, a common wiring for forming a storage capacitor via a part of the connection electrode and the gate insulating film, and an interlayer insulating film formed on the gate insulating film; An active matrix substrate having a liquid crystal driving display electrode and a counter electrode provided on the interlayer insulating film, a counter substrate facing the active matrix substrate, and sandwiched between the active matrix substrate and the counter substrate; A liquid crystal display device comprising: a liquid crystal layer, wherein the counter electrode is directly connected to the common line via a contact hole provided in the interlayer insulating layer. 5. A substrate, a gate signal line and a gate insulating film provided on the substrate, a source signal line provided on the gate insulating film, and each of the gate signal line and the source signal line. A thin film transistor formed at the intersection, a drain electrode connected to the thin film transistor,
A connection electrode connected to the drain electrode, a common wiring for forming a storage capacitor via a part of the connection electrode and the gate insulating film, and an interlayer insulating film formed on the gate insulating film; An active matrix substrate having a liquid crystal driving display electrode provided on the interlayer insulating film; and a liquid crystal driving counter electrode facing the active matrix substrate.
A liquid crystal display device comprising: a counter substrate substantially at the center of a region; a liquid crystal layer sandwiched between the active matrix substrate and the counter substrate. 6. The liquid crystal display device according to claim 5, wherein the display electrode is formed so as to overlap with the source signal wiring or the gate signal wiring. 7. The device according to claim 5, wherein the longitudinal direction of the counter electrode has a constant angle with respect to the longitudinal direction of the display electrode.
Or the liquid crystal display device according to claim 6. 8. The method according to claim 1, wherein said interlayer insulating layer has a thickness of 1.0 to 10.
The liquid crystal display device according to claim 1, wherein the thickness is 0 μm. 9. The dielectric constant of said interlayer insulating layer is 1.5 to 1.5.
The liquid crystal display device according to claim 1, wherein the ratio is 3.5. 10. The liquid crystal display device according to claim 1 , wherein the material of the interlayer insulating film is an organic resin. 11. The liquid crystal display device according to claim 1, wherein an image is displayed by driving the liquid crystal layer molecules in the display region to rotate in a direction substantially horizontal to the substrate surface. 12. A method for manufacturing a liquid crystal display device, comprising: forming a gate electrode on a substrate;
Forming a common wiring for forming a storage capacitor via a gate insulating layer; forming a gate insulating layer on the substrate so as to cover the gate electrode and the common wiring; Forming a source signal wiring and a connection electrode on the layer; forming a thin film transistor at an intersection of the gate signal wiring and the source signal wiring; and forming the thin film transistor and the connection on the gate insulating layer. Forming an interlayer insulating film so as to cover the electrode, the source signal wiring, and the gate signal wiring ; forming a liquid crystal driving display electrode and a counter electrode on the interlayer insulating film; Connecting the drain electrode connected to the thin film transistor and the display electrode via the connection electrode by a contact hole penetrating a part of the insulating film. 13. A method for manufacturing a liquid crystal display device, comprising: forming a gate electrode on a substrate;
Forming a common wiring for forming a storage capacitor via a gate insulating layer; forming a gate insulating layer on the substrate so as to cover the gate electrode and the common wiring; Forming a source signal wiring and a connection electrode on the layer; forming a thin film transistor at an intersection of the gate signal wiring and the source signal wiring; and forming the thin film transistor and the connection on the gate insulating layer. Forming an interlayer insulating film so as to cover the electrode, the source signal wiring, and the gate signal wiring ; forming a liquid crystal driving display electrode on the interlayer insulating film; Connecting a drain electrode connected to the thin film transistor and the display electrode via the connection electrode by a contact hole penetrating a part thereof; and opposing the display electrode via a liquid crystal layer. The counter electrode display territory that
Forming the region substantially at the center of the region .