JPH11271804A - Liquid crystal display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display which has a high holding capability to withstand low-frequency driving, can minimize a leak current from a capacity, and reduce power consumption without increasing its manufacturing cost. SOLUTION: Between a drain electrode arranged at one end of a dielectric material layer 102 and an auxiliary capacity electrode 101b arranged at the other end, electrodes 104c, 104c... are mounted intermittently on the top surface of the dielectric material layer 102, while electrodes 101c, 101c... are placed on the reverse surface so that the electrodes 104c, 104c... and 101c, and 101c... overlap partially with each other at both the ends. Capacitors are formed where they overlap with each other and their polarities cancel each other, so the polarities cancel on the whole auxiliary capacity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquid crystal display device represented by a thin film transistor.

[0002]

2. Description of the Related Art Since a liquid crystal display device has a feature that the device itself is lightweight and thin, it is widely used as a display element of a portable terminal or a screen for a large-screen thin television.

In particular, in recent years, the demand for portable terminals has been increasing, and there has been a strong demand for devices that can be driven by a battery for a long period of time, and reducing the power consumption of liquid crystal display devices has become a major issue.

Since it is considered effective to lower the frequency to reduce the power consumption, a liquid crystal display device having a higher holding capacity is desired.

Here, the structure of a conventional thin film transistor array (hereinafter, the thin film transistor may be referred to as “TFT”) will be described.

FIG. 14 is a sectional view of a conventional TFT array, and FIG. 15 is an equivalent circuit thereof.

In this TFT array, after a gate electrode 101a and an auxiliary capacitance electrode 101b are formed on a glass substrate, a gate insulating film 102, an amorphous Si layer 103,
It has a structure in which a source electrode 104a, a drain electrode 104b, a passivation layer 105, and a pixel electrode layer 106 are sequentially formed.

As shown in FIG. 14, in the conventional TFT array, an auxiliary capacitance element is formed by the drain electrode 104b and the auxiliary capacitance electrode 101b, and the electric charge held in the liquid crystal is accumulated by the auxiliary capacitance element. As a material of the gate insulating film 102 forming the auxiliary capacitance element, a dielectric constant of 4
The degree of SiO _x and the dielectric constant and 6 about SiN _x have been used. In order to form a capacitor with higher holding ability using these materials, the area of the capacitor needs to be increased. However, when the area of the capacitive element is increased, the light use efficiency is reduced, and an additional power for compensating the light use efficiency is required, so that it is not very effective in reducing the power consumption.

For this reason, recently, the dielectric constant of T
High dielectric constant materials such as aO _x have come to be used.
This is because if a material having a higher dielectric constant is used for a device having the same design as that of the related art, a liquid crystal display device having a higher holding capacity can be obtained.

However, when such a high dielectric constant material is used, the leakage current is increased only by forming the conventional material having a thickness of about several hundred nm, and it is not always possible to obtain a high holding ability.

On the other hand, if the film is formed as a thick film having a thickness of about several 1000 nm, the leakage is considerably reduced, but the cost is increased from the viewpoint of throughput in order to form a film having such a thick film. There is.

Further, when the film thickness is increased, the magnitude of the leak current varies in the film thickness direction depending on the polarities of the upper and lower electrodes.
When the liquid crystal is actually driven, there is a problem that a residual direct current component is generated even if the liquid crystal is driven by an alternating current.

That is, as long as one auxiliary capacitance element is formed, a polarity is generated in the film thickness direction as shown in FIG. 15, which causes a problem that the retention characteristics are different between the plus writing and the minus writing.

[0014]

SUMMARY OF THE INVENTION The present invention has been made to solve such problems.

[0015] That is, an object of the present invention is to provide a liquid crystal display device having a high holding ability capable of withstanding low frequency driving.

Another object of the present invention is to provide a liquid crystal display device capable of reducing a leakage current from a capacitive element as much as possible which causes a burn-in of a liquid crystal during AC driving.

It is a further object of the present invention to provide a liquid crystal display device capable of reducing power consumption without increasing manufacturing costs.

[0018]

According to a first aspect of the present invention, there is provided a liquid crystal display device comprising: a liquid crystal layer sandwiched between a first electrode and a second electrode; An applying means for selecting a signal and applying a voltage corresponding to the display signal to the first electrode; a first capacitive element disposed between the first electrode and the applying means; A second capacitor disposed between the first capacitor and the first electrode, the second capacitor having a polarity opposite to that of the first capacitor.

According to a second aspect of the present invention, there is provided a liquid crystal display device.
A liquid crystal layer sandwiched between the first electrode and the second electrode;
Applying means for selecting a display signal and applying a voltage corresponding to the display signal to the first electrode; a first capacitive element disposed between the first electrode and the applying means; A second capacitor disposed in parallel between the first capacitor and the first electrode and having a polarity opposite to that of the first capacitor.

According to a third aspect of the present invention, there is provided a liquid crystal display device comprising:
A liquid crystal layer sandwiched between the first electrode and the second electrode;
An applying means for selecting a display signal and applying a voltage corresponding to the display signal to the first electrode; and an applying means arranged in parallel with the liquid crystal layer between the first electrode and the applying means. A first capacitive element, and a second capacitive element disposed between the first capacitive element and the first electrode and having a polarity opposite to that of the first capacitive element. I do.

According to a fourth aspect of the present invention, there is provided a liquid crystal display device comprising:
A liquid crystal layer sandwiched between the first electrode and the second electrode;
An applying means for selecting a display signal and applying a voltage corresponding to the display signal to the first electrode; and an applying means arranged in parallel with the liquid crystal layer between the first electrode and the applying means. A first capacitor, and a second capacitor disposed in parallel with the liquid crystal layer between the first capacitor and the first electrode, the second capacitor having a polarity opposite to the polarity of the first capacitor. And a capacitor.

According to a fifth aspect of the present invention, there is provided a liquid crystal display device comprising:
4. The liquid crystal display device according to claim 1, wherein, as the capacitive element, a dielectric layer disposed between the first electrode and the application unit, and a dielectric layer disposed on one surface of the dielectric layer. 5. A first electrode layer in which a plurality of first intermediate electrodes are disposed at predetermined intervals, and a second electrode in which a plurality of second intermediate electrodes are disposed on the other surface of the dielectric layer. Each is
A second electrode layer disposed at a position straddling two adjacent electrodes on the first electrode layer.

In the liquid crystal display device according to the present invention, two capacitance elements, the first capacitance element and the second capacitance element, are arranged in series with the liquid crystal layer, and the polarity of the first capacitance element is changed. And the polarities of the second capacitive element are opposite to each other, the polarities of the capacitive elements cancel each other out, and the polarity of the entire capacitive element becomes almost zero. As a result, the holding capacity can be increased without increasing the leakage current from the capacitor. Further, it is possible to prevent the liquid crystal from burning due to a leak current.

Furthermore, since the required holding capacity is secured by using two capacitors in combination, it is not necessary to increase the thickness of the dielectric, and the manufacturing cost can be reduced.

In the liquid crystal display device according to the present invention, two capacitance elements, the first capacitance element and the second capacitance element, are disposed in parallel with the liquid crystal layer, and the polarity of the first capacitance element is changed. And the polarities of the second capacitive element are opposite to each other, the polarities of the capacitive elements cancel each other out, and the polarity of the entire capacitive element becomes almost zero. As a result, the holding capacity can be increased without increasing the leakage current from the capacitor. Further, it is possible to prevent the liquid crystal from burning due to a leak current.

Furthermore, since the necessary holding capacity is secured by using two capacitors in combination, it is not necessary to increase the thickness of the dielectric, and the manufacturing cost can be reduced.

In the liquid crystal display device according to the third aspect, two capacitance elements, the first capacitance element and the second capacitance element, are disposed in parallel with the liquid crystal layer, and the polarity of the first capacitance element is changed. And the polarities of the second capacitive element are opposite to each other, the polarities of the capacitive elements cancel each other out, and the polarity of the entire capacitive element becomes almost zero. As a result, the holding capacity can be increased without increasing the leakage current from the capacitor. Further, it is possible to prevent the liquid crystal from burning due to a leak current.

Furthermore, since the necessary holding capacity is secured by using two capacitors in combination, it is not necessary to increase the thickness of the dielectric, and the manufacturing cost can be reduced.

According to a fourth aspect of the present invention, in the liquid crystal display device, two capacitance elements, the first capacitance element and the second capacitance element, are disposed in parallel with the liquid crystal layer, and the polarity of the first capacitance element is changed. And the polarities of the second capacitive element are opposite to each other, the polarities of the capacitive elements cancel each other out, and the polarity of the entire capacitive element becomes almost zero. As a result, the holding capacity can be increased without increasing the leakage current from the capacitor. Further, it is possible to prevent the liquid crystal from burning due to a leak current.

Further, since the necessary holding capacity is secured by using two capacitors in combination, it is not necessary to increase the thickness of the dielectric, and the manufacturing cost can be reduced.

In the liquid crystal display device according to the fifth aspect, as the capacitive element, a predetermined distance is provided on one surface of a dielectric layer disposed between the first electrode and the applying means. A plurality of electrode plates are intermittently arranged, and a plurality of electrode plates are arranged on the other surface at positions straddling two adjacent electrode plates of the electrode plate.

In this capacitive element, electrode plates are provided at alternate positions on both surfaces of the dielectric layer, and the same electric capacity as when a plurality of capacitive elements are connected in series can be secured. Can be higher.

Further, since the same number of polarities are formed in the capacitive element in opposite directions, they are canceled each other, and the leak current becomes almost zero.

Further, since a thick dielectric layer is not used, an increase in manufacturing cost can be suppressed.

[0035]

Embodiments of the present invention will be described below.

(First Embodiment) FIGS. 1 and 2 show the configuration of a liquid crystal display device according to a first embodiment of the present invention.

FIG. 1 is a vertical sectional view of the liquid crystal display device according to the present embodiment, and FIG. 2 is an equivalent circuit thereof.

In the liquid crystal display device of this embodiment, a drain electrode is connected to the left end of the dielectric material layer 102 in the figure, and an auxiliary capacitance electrode 101b is provided at a lower right position in the figure.

Further, on the upper surface of the dielectric material layer 102, a plurality of electrodes 104c, 104c.
1c, 101c... Are intermittently arranged, respectively.
The electrodes 104c, 104c ... and the electrodes 101c, 101c ...
Means that one electrode 101c is arranged at a position between two adjacent electrodes 104c, 104c,
The vicinity of both left and right ends of this one electrode 101c in the drawing is the two electrodes 104c, 1c facing each other via the dielectric material layer 102.
04c is disposed at a position overlapping with each end portion.

In this liquid crystal display device, a plurality of electrodes 101c, 101c alternately arranged on the upper and lower surfaces of the dielectric material layer 102, the drain electrode 104b, the auxiliary capacitance electrode 101b, and the dielectric material layer 102 are used. And the electrodes 104c, 104c,... Are formed as a series capacitor between the drain electrode 104b at both ends of the dielectric material layer 102 and the auxiliary capacitance electrode 101b via the electrodes 101c, 104c.

With such a structure, one capacitor is formed by a pair of electrodes 101c and 104c facing each other with the dielectric material layer 102 interposed therebetween, and it is equivalent to connecting a number of these capacitors in series. Circuit is formed.

Therefore, even when the dielectric material layer 102 has a small thickness, a capacitor having a structure in which a plurality of capacitors are connected in series is formed. Is obtained.

Even though each capacitor has a polarity, it is formed so that the polarities are opposite to each other, so that the polarities cancel each other out, and the individual polarities are canceled as a whole. As a result, it is the same as having no polarity in the whole capacitor element, so that leakage current can be suppressed.

In particular, if the number of series capacitors formed by arranging the upper and lower electrodes at alternate positions is set to be an even number, as shown in FIG. Since the numbers become equal and the polarities having the same strength and opposite directions cancel each other, the polarity difference of the leak current in the film thickness direction can be completely canceled. As a result, leakage current can be suppressed.

The dielectric material layer 102 of each capacitor
Since the film thickness itself is small, an increase in manufacturing cost can be suppressed.

The following second to sixth embodiments, including this embodiment, do not limit the scope of the present invention.

That is, in the first embodiment, as shown in the equivalent circuit of FIG. 2, an auxiliary capacitor 203 is connected in parallel to the liquid crystal display layer 202, and a plurality of capacitors 203a and Although the liquid crystal display device has a configuration in which 203b are connected in series so that the polarities are opposite to each other, the polarities are offset by combining a plurality of capacitors having opposite polarities in other configurations. What is necessary is just what was connected so that it might be.

For example, as shown in FIG. 3A, an auxiliary capacitor 203 is connected in parallel to the liquid crystal display layer 202, and a plurality of capacitors 203a and 203b constituting the auxiliary capacitor 203 are connected in the opposite directions. It is also possible to adopt a configuration in which the components are connected in parallel.

Further, as shown in FIG.
02 and a plurality of capacitors 203a and 203a constituting the auxiliary capacitance 203.
03b are connected in series so that their polarities are opposite to each other, or as shown in FIG.
02 and a plurality of capacitors 203a and 203a constituting the auxiliary capacitance 203.
03b may be connected in parallel so that the polarities are opposite to each other.

(Second Embodiment) Next, a liquid crystal display device according to a second embodiment of the present invention will be described.

FIG. 4 is a vertical sectional view of the liquid crystal display device according to the second embodiment, and FIG. 5 is an equivalent circuit thereof.

In the liquid crystal display device of this embodiment, an auxiliary capacitance element is formed by connecting two capacitors 203a and 203b in parallel. In the first dielectric material layer 102b, a lower electrode 101d disposed below the first dielectric material layer 102b is connected to the source electrode 104b to form an auxiliary capacitance upper electrode, and the auxiliary capacitance lower electrode is formed by the upper electrode 104d.

On the other hand, in the second dielectric material layer 102c,
The upper electrode 104e and the source electrode 104b are connected to the pixel electrode 1
06, and the lower electrode 104b is used as an auxiliary capacitance lower electrode. Note that the auxiliary capacitance lower electrode 104d and the auxiliary capacitance lower electrode 101b are connected by an electrode 107.

In the liquid crystal display device of this embodiment, FIG.
As shown in (2), since two capacitors 203a and 203b having different polarities in the upper and lower film thickness directions are formed in parallel with each other, the polarities cancel each other out, and as a result, a leak current can be suppressed.

(Third Embodiment) Next, a liquid crystal display device according to a third embodiment of the present invention will be described.

FIG. 6 is a vertical sectional view of a liquid crystal display device according to a third embodiment of the present invention, and FIG. 7 is a plan view of the liquid crystal display device.

Hereinafter, a method for manufacturing the liquid crystal display device according to this embodiment will be described.

First, a metal layer 302 was formed on a transparent substrate 301 and patterned to form a dielectric lower electrode. Although quartz is used as the transparent substrate 301, a glass substrate, an MgO substrate, or plastic may be used.

In this embodiment, first, Ti was sputtered to a thickness of 200 A (angstrom), and Pt was sputtered thereon to a thickness of 2000 A (angstrom). In particular, an oxide conductor such as IrO _x or RuO _x can be used as the lower electrode of the dielectric. Mo and Al are MoT
a, MoW, etc. can also be used. The electrode 30
In pattern 2, the taper shape of about 30 to 60 degrees improved the dielectric breakdown voltage and reduced the leakage current.

Next, SrTiO 3 is formed by sputtering.
₃ was formed to a thickness of 3000 A (angstrom). Thereafter, annealing was performed at 500 ° C. for 1 hour in an O ₂ atmosphere in order to crystallize the dielectric. Next, the dielectric is patterned.
To form a dielectric layer 303. As the dielectric, oxides such as TaO _x , perovskite oxides,
Alternatively, a composite film of any of these plural dielectrics may be used, and an inorganic dielectric film or an organic dielectric film may be used.

Next, a metal layer 304 was formed thereon by sputtering. In the present embodiment, Pt is set to 200
0A (angstrom), but also like the lower electrode, a laminated film of Pt and Ti, IrO _x , RuO
_x or the like may be used.

Next, MoTa was sputtered to a thickness of 2000 A (angstrom) to form a film, and was patterned by dry etching to form a drain electrode, a signal line 305a, and a source electrode 305b of the TFT.

Next, a contact layer 306 was formed. In this embodiment, n ⁺ amorphous silicon is
A film was formed to a thickness of 0A (angstrom) and patterned by a dry etching method. Thereafter, the amorphous silicon 307 was continuously formed to a thickness of 3000 A (angstrom) and the SiN _x 308 was formed to a thickness of 300 A (angstrom) by a CVD method.

Next, SiN is formed by dry etching.
_{The x} layer, the amorphous silicon layer, and the n ⁺ amorphous silicon layer were continuously etched to form TFT islands.

As 307, after amorphous silicon is formed, it may be polycrystallized by laser annealing or the like. The SiN _x layer 308 is also SiO _x , TaO
Other insulators such as _x may be used, and a stacked film of these may be used. After that, the gate electrode layer 30
9 was formed. In this embodiment, the laminated film of Mo and Al
Although formed to a thickness of 000 A (Angstrom), any of the above-mentioned metals can also be used.

Next, the SiN _x layer is deposited by CVD method to a thickness of 20 μm.
The inorganic passivation layer 310 was formed by forming a film having a thickness of 00A (angstrom) and patterning it by a dry etching method to form through holes and the like. Further, a film was formed by coating an acrylic resin with a thickness of 2 μm, and patterning was performed by dry etching to form through holes and the like, thereby forming an organic passivation layer 311.

In this embodiment, an acrylic resin is used.
Polyimide or BCB (benzocyclolobutene) may be used. Since BCB has a small dielectric constant of about 3, it is effective in reducing the coupling capacitance between the pixel electrode and the signal line or the TFT. Further, a black resin may be used. Further, a stacked film of these organic materials may be used.

Further, the pixel electrode layer 312 was formed by sputtering and patterning. In this embodiment, ITO is used. However, if a metal having a high reflectance such as Al is used, it is effective in combination with a liquid crystal in a reflection mode. In addition, the organic passivation layer allows the array to have good flatness, has little disclination of liquid crystal, and has good display characteristics. Since the passivation layer also used SiN _x having a large stopping power against impurity ions such as Na, deterioration of display performance was small even when driving for a long time. Also, the pattern of the pixel electrode
In this example, ITO was etched with a hydrochloric acid-based etchant in this example, but the composite film of the organic passivation layer and the inorganic passivation layer did not corrode the underlying signal green or gate line.

On one transparent substrate 313, the counter electrode layer 31 is provided.
As No. 4, ITO was formed to a thickness of 1000 A (angstrom). As the transparent substrate, a glass substrate, a quartz substrate, a plastic substrate, an MgO substrate, or the like can be used. This glass substrate and the above-mentioned TFT array substrate were combined, and a TN (twisted nematic) liquid crystal 315 was injected with an appropriate gap by using a spacer or the like to complete a liquid crystal display device.

The liquid crystal layer 315 may be a GH (guest host) mode, an OCB mode, or an IPS mode (in-plane switching mode; horizontal electric field mode). A polymer dispersed liquid crystal, a ferroelectric liquid crystal, an antiferroelectric liquid crystal, or the like can be used. In this embodiment, an example in which the liquid crystal layer is a single layer is shown, but a liquid crystal layer may be a multilayer.

In this embodiment, an inverted stagger type top gate type TFT is used for the TFT, but a normal stagger type TFT may be used. A bottom gate type may be used, and amorphous silicon, microcrystalline silicon, polycrystalline silicon, silicon germanium, or the like may be used for a semiconductor portion.

In the liquid crystal display device of the present embodiment, the drain electrode 305b is connected to the left end of the dielectric layer 303 in the figure,
An auxiliary capacitance electrode 304c is provided at the right end position in the drawing. Further, a plurality of electrodes 304a are provided on the upper surface of the dielectric layer 303.
And 304b, a plurality of electrodes 302a, 302
b and 302c are intermittently arranged. The electrodes 304a and 304b and the electrodes 302a to 302c are arranged such that the electrode 304a is located between two adjacent electrodes 302a and 302b.
The electrode 304b is disposed so as to be located between 302c. The vicinity of both left and right ends of the electrode 302a in the drawing is disposed so as to overlap with the respective ends of the drain electrode 305b and the electrode 304a opposed to each other via the dielectric material layer 303. Similarly, the electrode 302b is disposed between the opposing electrodes 304a and 304b, the electrode 302c is disposed between the opposing electrodes 304b and 304c, and the upper and lower surfaces of the dielectric layer 303 are disposed. The electrodes arranged at the respective positions are arranged at alternate positions while overlapping each other at the ends.

In this liquid crystal display device, the auxiliary capacitance element is composed of a plurality of electrodes 302a to 302c and 304a alternately arranged on the upper and lower surfaces of the dielectric layer 303, the drain electrode 305b, the auxiliary capacitance electrode 304c, and the dielectric layer 303. , And 304b, forming a series capacitor with electrodes 302a to 302c, 304a, and 304b interposed between the drain electrode 305b and the auxiliary capacitance electrode 304c at both ends of the dielectric layer 303.

With such a structure, a pair of electrodes facing each other via the dielectric layer 303, for example, the electrode 30
One capacitor is formed by the left end of 4a and the right end of electrode 302a. If attention is paid to this capacitor, an alternating current is applied at the time of energization, and charges are accumulated. When the current is cut off, it is ideal that the electric charge stored here is released and the electric charge becomes zero. However, since some electric charge remains, the capacitor has polarity. Assume now that the left end of the electrode 304a and the electrode 302a
It is assumed that the capacitor formed with the right end portion of FIG.

Here, the right end of the electrode 304a and the electrode 302
Focusing on the left end of b, another capacitor is also formed during this time. In this capacitor, polarization occurs at the electrode 304a and the electrode 302a, respectively.
Has a polarity opposite to the polarity of the capacitor formed by the left end of the capacitor 302 and the right end of the electrode 302a. Therefore, opposite polarities exist at the left and right ends of the electrode 304a, and these mutually cancel each other, so that the appearance is the same as the absence of the polarities.

Similarly, the overlapping portion between the drain electrode 305b and the electrode 302a, the left end of the electrode 304b and the electrode 3
02, a capacitor is also formed at an overlapping portion between the right end of the electrode 304b and the left end of the electrode 302c, and at an overlapping portion between the right end of the electrode 302c and the left end of the electrode 304c. Is formed with a total of six capacitors. Each capacitor has a polarity, and these polarities cancel each other. For this reason, the entire auxiliary capacitance element has the same state as having no polarity, and the leakage current can be suppressed.

Further, in this liquid crystal display device, a circuit equivalent to connecting the six capacitors in series is formed, so that the thickness of the dielectric layer 303 can be substantially increased without increasing the film thickness. A large holding capacity equivalent to that of a capacitive element having a large film thickness can be obtained.

Further, the dielectric material layer 102 of each capacitor
Since the film thickness itself is small, an increase in manufacturing cost can be suppressed.

In the present embodiment, the number of capacitors connected in series in terms of an equivalent circuit is six, but any other number of capacitors can be formed. However, when the number is set to an even number, it is possible to obtain a display characteristic with less burn-in. In the present embodiment, the overlapping portion of the upper electrode 304 and the lower electrode 302 is formed to have substantially the same size, but may be different.

(Fourth Embodiment) Next, a liquid crystal display device according to a fourth embodiment of the present invention will be described.

FIGS. 8A to 8C are vertical sectional views of a liquid crystal display device according to the fourth embodiment of the present invention.

The liquid crystal display of this embodiment is a modification of the liquid crystal display of the third embodiment. The description overlapping with the description of the liquid crystal display device according to the third embodiment will be omitted.

In the liquid crystal display device of the present invention, the structure shown in the present embodiment can be adopted.

In the liquid crystal display device shown in FIG. 8A, a dielectric layer 601 is etched to form a concave portion, a metal layer is formed, and then a flattening process such as a CMP (chemical mechanical etching) method is performed. Completely flat lower electrode 602
To form Next, a dielectric layer 603 forming a plurality of adjacent capacitors is formed and patterned, and then an upper electrode 604 is formed, and a passivation 605 layer and a pixel electrode layer 606 are formed.

In the liquid crystal display device having this structure, the dielectric 603
Is the lower electrode 602 and the dielectric layer 6 forming a flat surface.
01, so that the dielectric 603 overlies it.
It is characterized by the fact that a leak is unlikely to occur.

In the liquid crystal display device shown in FIG. 8B, the dielectric covers the lower electrode 602 forming the projection, but the dielectric is formed between the dielectric layer 603 and the upper electrode layer 604. A body layer 607 is formed. Therefore, the dielectric layer 6
In 03, the portion covering the step of the lower electrode 602 is relaxed by the dielectric 607, so that the electric field applied to the upper electrode 604 is reduced, so that leakage is less likely to occur.

In the liquid crystal display device shown in FIG. 8C, the dielectric layer 603 is patterned in an island shape, and the dielectric layer 607 is formed therebetween. With such a structure, the dielectric 603 forming a plurality of adjacent capacitors is formed.
Is reduced.

The dielectric layer 607 preferably has a lower dielectric constant than the dielectric 603. In this embodiment, BCB is used, but any of the dielectrics described in this embodiment can be used. In addition, a passivation layer is formed between a plurality of adjacently formed capacitors and the pixel electrode 606.
The layers (605a, 605b) were provided, and a shield electrode layer 608 was formed therebetween. When the shield electrode 608 was driven, it was fixed at a ground potential or an appropriate potential. Thus, the coupling capacitance between the upper electrode 604 and the pixel electrode 606 can be reduced. The shield electrode 608 was also formed between the TFT and the pixel electrode. Thus, the coupling capacitance between the TFT and the pixel electrode can be reduced.

In this embodiment, one TFT and one dielectric element are connected to one pixel, but a plurality of TFTs and dielectric elements may be connected to one pixel. Thereby, the redundancy of the TFT and the dielectric array is increased, and a point defect due to a defect of the TFT or the dielectric element portion in the display element can be prevented. Conversely, one TFT may be connected to a plurality of pixels via a plurality of dielectrics having different numbers of chains. With such a configuration, the divided pixels can be formed, and the potential corresponding to the number of capacitors connected in series can be held in the liquid crystal, so that the area gradation can be achieved. For example, it is effective to combine with a liquid crystal which only takes a binary state, such as an antiferroelectric liquid crystal.

(Fifth Embodiment) Next, a liquid crystal display device according to a fifth embodiment of the present invention will be described.

FIG. 9 is a vertical sectional view of a liquid crystal display according to a fifth embodiment of the present invention, and FIG. 10 is a plan view of the liquid crystal display.

Hereinafter, a method for manufacturing the liquid crystal display device according to the present embodiment will be described.

First, Pt having a thickness of 1
A film was formed by sputtering to a thickness of μm, and patterning was performed to form electrode layers 402 and 404. Metal layer 4
As 02 and 404, any of the metals described in the above embodiment may be used.

Next, SrTiO ₃ was deposited to a thickness of 1 μm and patterned to form a dielectric layer 403. As the dielectric material, any of the dielectric materials in the above embodiments can be used. Thereafter, a metal layer 405 was formed by sputtering and patterned to form a drain electrode and a signal line electrode 405a of the TFT, a source electrode 405b, and a connection electrode 405c between a dielectric and a pixel electrode.

In this embodiment, MoTa is used, but any metal material used in the above embodiments can be used.

Next, a contact layer 406 having a thickness of 500
A (Angstrom), amorphous silicon layer 40
7 is 3000A (angstrom), insulating layer 4
08 was formed to have a thickness of 3000 A (angstrom), the gate electrode layer 409 was formed to have a thickness of 2000 A (angstrom), and a TFT was formed. This is the T
Similar to the formation of FT. Therefore, the TFT may have any other structure described in the above embodiment. In the manufacturing process, the inorganic passivation layer 410,
Although the organic passivation layer 411 and the pixel electrode layer 412 were formed, the steps are exactly the same as those in the above-described embodiment. That is, any of the materials described above may be used as the material.

This was combined with a counter substrate similar to that of the above-described embodiment, and a liquid crystal was injected with an appropriate gap to produce a liquid crystal display device. Regarding the structure of the liquid crystal material and the liquid crystal layer, a plurality of patterns similar to those of the above-described embodiment can be formed.

The features of the liquid crystal display device according to this embodiment are as follows.
That is, the capacitance of the dielectric is formed not in the deposition direction (vertical direction in the figure) but in the horizontal direction between the left and right electrodes 402 and 404 in the figure.

Therefore, the thickness of the dielectric layer can be changed only by changing the pattern of the electrodes 402 and 404. In particular, it is easy to obtain a large film thickness of about 5 μm to 10 μm. In the present embodiment, the electrodes 402 and 404
Was 10 μm.

In the liquid crystal display device of this embodiment, the dielectric layer 403 of the auxiliary capacitance element and the electrodes 402 and 403 to be disposed on both sides of the dielectric layer 403 are arranged in the longitudinal direction of the liquid crystal display device, that is, in the figure. Since they are arranged in the horizontal direction, the thickness of the dielectric layer 403 can be increased regardless of the thickness of the liquid crystal display device. As a result, the storage capacity of the auxiliary capacitance element can be increased.

Since the heights of the electrodes 402 and 404 are sufficiently increased, of the auxiliary capacitance elements arranged in the horizontal direction,
The width of the dielectric layer 403 was sufficiently secured. Therefore, the width of the auxiliary capacitance element can be made sufficiently large, and as a result, the holding capacity of the auxiliary capacitance element can be increased.

(Sixth Embodiment) Next, a sixth embodiment of the present invention will be described.
The liquid crystal display device according to the embodiment will be described.

FIG. 11 is a vertical sectional view of a liquid crystal display according to a sixth embodiment of the present invention, and FIG. 12 is a plan view of the liquid crystal display.

Hereinafter, a method for manufacturing the liquid crystal display device according to the present embodiment will be described.

On a transparent substrate, ITO was sputtered to a thickness of 2000 A (angstrom) to form a film, and then patterned to form a dielectric lower electrode 502 and a TFT.
Drain, signal line electrode 505a, source electrode 505b
Was formed. Although quartz is used as the transparent substrate, any other substrate described in the above embodiment can be used.

Next, SrTiO ₃ was sputtered to a thickness of 3000 A (angstrom) to form a film, and then patterned to form a striped dielectric layer 503.
Next, a dielectric upper electrode 504 was formed. In this embodiment, ITO is used. For the dielectric layer 503 and the upper and lower electrode layers, any of the materials described in the above embodiments can be used.

In particular, when a reflection mode liquid crystal is used, the lower electrode is a laminated film of Pt and Ti (Pt on Ti), and the upper electrode is a laminated film of Al and Pt (Al on Pt). Is preferred.

Next, the contact layer 506 is formed to a thickness of 500A.
(Angstrom), amorphous silicon layer 507
3000 A (angstrom), insulator layer 508 with 3000 A (angstrom), gate metal layer 509
Are formed to a thickness of 2000 A (angstrom), respectively, to form a TFT. This is also the same as the process of the above-described embodiment. Regarding the structure of the TFT, any structure similar to that of the above-described embodiment can be used.

Next, the passivation layer 510 is
A (angstrom) was formed. Although SiN _x is used for the passivation 510, an organic material may be used, or a stack of these may be used, as in the above-described embodiment.

This was combined with a counter substrate similar to that of the above-described embodiment, and a TN liquid crystal was injected with an appropriate gap to complete a liquid crystal display device. A plurality of patterns can be used for the liquid crystal material and the structure of the liquid crystal layer as in the above-described embodiment.

FIG. 13 is a circuit diagram showing the features of this embodiment. In FIG. 13, the number of capacity connected in series is 5
Are shown.

In the present embodiment, one of the capacities 524a to 524a to 440a to 440c connected in series in the form of a chain formed by a dielectric layer.
524e are in series with the liquid crystals 525a to 525c, respectively.

Further, since 524a to 524e are connected in series, three kinds of electric fields can be applied to the liquid crystal even if one kind of electric field is written in the dielectric and the liquid crystal from the TFT.

Of course, in general, (2n-1) pieces (n ≧
If the series capacitance of 1) is formed, n electric fields can be applied. Therefore, in this configuration, area gradation can be performed.
Thus, multi-gradation display is possible even with a liquid crystal material that can take only two values, such as an antiferroelectric liquid crystal.

[0115]

As described in detail above, according to the present invention, it is possible to provide a liquid crystal display device having a high holding ratio, capable of controlling gradation, and capable of obtaining a high-quality image with high reliability at a low price. .

That is, according to the first aspect of the present invention, two capacitance elements, the first capacitance element and the second capacitance element, are arranged in series with respect to the liquid crystal layer, and the first capacitance element is provided. Since the polarity of the element and the polarity of the second capacitance element are arranged to be opposite to each other, the polarity of the capacitance element is canceled, and the polarity of the entire capacitance element becomes almost zero. As a result, the holding capacity can be increased without increasing the leakage current from the capacitor. Further, it is possible to prevent the liquid crystal from burning due to a leak current.

Furthermore, since the necessary holding capacity is secured by using two capacitive elements in combination, it is not necessary to increase the thickness of the dielectric, and the manufacturing cost can be reduced.

According to the second aspect of the present invention, the first
And two capacitors, a second capacitor and a second capacitor, are disposed in parallel to the liquid crystal layer so that the polarity of the first capacitor and the polarity of the second capacitor are opposite to each other. , The polarities of the capacitive elements are canceled out, and the polarities of the capacitive elements as a whole become almost zero. As a result, the holding capacity can be increased without increasing the leakage current from the capacitor. Further, it is possible to prevent the liquid crystal from burning due to a leak current.

Furthermore, since the necessary holding capacity is secured by using two capacitors in combination, it is not necessary to increase the thickness of the dielectric, and the manufacturing cost can be reduced.

According to the third aspect of the present invention, the first
And two capacitors, a second capacitor and a second capacitor, are disposed in parallel to the liquid crystal layer so that the polarity of the first capacitor and the polarity of the second capacitor are opposite to each other. , The polarities of the capacitive elements are canceled out, and the polarities of the capacitive elements as a whole become almost zero. As a result, the holding capacity can be increased without increasing the leakage current from the capacitor. Further, it is possible to prevent the liquid crystal from burning due to a leak current.

Furthermore, since the necessary holding capacity is secured by using two capacitors in combination, it is not necessary to increase the thickness of the dielectric, and the manufacturing cost can be reduced.

According to the fourth aspect of the present invention, the first
And two capacitors, a second capacitor and a second capacitor, are disposed in parallel to the liquid crystal layer so that the polarity of the first capacitor and the polarity of the second capacitor are opposite to each other. , The polarities of the capacitive elements are canceled out, and the polarities of the capacitive elements as a whole become almost zero. As a result, the holding capacity can be increased without increasing the leakage current from the capacitor. Further, it is possible to prevent the liquid crystal from burning due to a leak current.

Further, since the necessary holding capacity is secured by using two capacitors in combination, it is not necessary to increase the thickness of the dielectric, and the manufacturing cost can be reduced.

According to the fifth aspect of the present invention, a first aspect is provided.
Or the liquid crystal display device according to 3, wherein the capacitor element is intermittently provided at a predetermined interval on one surface of a dielectric layer disposed between the first electrode and the application unit. A structure in which a plurality of electrode plates are provided and a plurality of electrode plates are provided on the other surface at positions straddling two adjacent electrode plates of the electrode plate.

In this capacitive element, electrode plates are provided at alternate positions on both surfaces of the dielectric layer, and the same electrical capacity as that obtained by connecting a plurality of capacitive elements in series can be secured. Can be higher.

Further, since the same number of polarities are formed in the capacitive element in opposite directions, they are canceled each other, and the leak current becomes almost zero.

Further, since a thick dielectric layer is not used, an increase in manufacturing cost can be suppressed.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view of a liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is an equivalent circuit of the liquid crystal display device according to the first embodiment of the present invention.

FIG. 3 is an equivalent circuit of a liquid crystal display device according to a modification of the first embodiment of the present invention.

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

FIG. 5 is an equivalent circuit of a liquid crystal display device according to a second embodiment of the present invention.

FIG. 6 is a vertical sectional view of a liquid crystal display device according to a third embodiment of the present invention.

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

FIG. 8 is a vertical sectional view of a liquid crystal display device according to a fourth embodiment of the present invention.

FIG. 9 is a vertical sectional view of a liquid crystal display device according to a fifth embodiment of the present invention.

FIG. 10 is a plan view of a liquid crystal display device according to a sixth embodiment of the present invention.

FIG. 11 is a vertical sectional view of a liquid crystal display device according to a sixth embodiment of the present invention.

FIG. 12 is a plan view of a liquid crystal display device according to a fifth embodiment of the present invention.

FIG. 13 is an equivalent circuit of a liquid crystal display device according to a fifth embodiment of the present invention.

FIG. 14 is a sectional view of a conventional TFT array.

FIG. 15 is an equivalent circuit of a conventional TFT array.

[Explanation of symbols]

 101a ... Gate electrode 101b ... Auxiliary capacitance electrode 101c ... Auxiliary capacitance intermediate electrode 102 ... Gate green insulation film 102a ... Gate electrode 102b ... Auxiliary capacitance element 102c ... Auxiliary capacitance element 103 ... Amorphous silicon layer 104a ... Drain electrode 104b ... Source electrode 105 ... Passivation layer 105a ... Passivation layer 105b ... Passivation layer 106 ... Pixel electrode 107 ... Auxiliary capacitance lower connection Electrode 201: TFT 202: Liquid crystal capacitance

 ──────────────────────────────────────────────────続 き Continued from the front page (72) Inventor Takeshi Hioki 33, Shinisogo-cho, Isogo-ku, Yokohama-shi, Kanagawa Prefecture Toshiba Production Engineering Laboratory Co., Ltd.

Claims (5)

[Claims] A liquid crystal layer sandwiched between a first electrode and a second electrode; and an application unit for selecting a display signal and applying a voltage corresponding to the display signal to the first electrode. A first electrode disposed between the first electrode and the applying means;
And a second capacitor disposed between the first capacitor and the first electrode, the second capacitor having a polarity opposite to the polarity of the first capacitor. A liquid crystal display device characterized by the above-mentioned. 2. A liquid crystal layer sandwiched between a first electrode and a second electrode; and an application unit for selecting a display signal and applying a voltage corresponding to the display signal to the first electrode. A first electrode disposed between the first electrode and the applying means;
And a second capacitor disposed in parallel between the first capacitor and the first electrode and having a polarity opposite to that of the first capacitor. A liquid crystal display device comprising: 3. A liquid crystal layer sandwiched between a first electrode and a second electrode; and an application unit for selecting a display signal and applying a voltage corresponding to the display signal to the first electrode. A first capacitance element disposed in parallel with the liquid crystal layer between the first electrode and the application means; and a first capacitance element disposed between the first capacitance element and the first electrode. And a second capacitor having a polarity opposite to the polarity of the first capacitor. 4. A liquid crystal layer sandwiched between a first electrode and a second electrode; and an application unit for selecting a display signal and applying a voltage corresponding to the display signal to the first electrode. A first capacitive element disposed in parallel with the liquid crystal layer between the first electrode and the applying unit; and a liquid crystal layer between the first capacitive element and the first electrode. And a second capacitor having a polarity opposite to that of the first capacitor, the second capacitor being disposed in parallel with the first capacitor. 5. The liquid crystal display device according to claim 1, wherein the capacitance element comprises: a dielectric layer disposed between the first electrode and the application unit; and the dielectric layer. A first electrode layer disposed on one surface of the first electrode and a plurality of first intermediate electrodes disposed at predetermined intervals, and disposed on the other surface of the dielectric layer, Multiple second
A liquid crystal display device, wherein each of the intermediate electrodes comprises: a second electrode layer disposed at a position straddling two adjacent electrodes on the first electrode layer.