JPH1068955A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to inexpensively obtain an element which is capable of maintaining a uniform cell gap in spite of action of external force thereon, has a high opening rate and contrast and has a good display grade by arranging columnar spaces functioning as auxiliary capacitors for holding the voltage impressed on pixel electrodes on switching elements. SOLUTION: A counter substrate 12 has a transparent glass substrate 21. Color filters 22 and transparent counter electrodes 23 consisting of ITO are successively laminated and formed over the entire part of the inside surface of the glass substrate 21. Further, transparent oriented films 20 consisting of polyimide, etc., are formed on the counter electrodes 23. The columnar spacers 40 are disposed in the regions between source electrodes 27 of respective TFs 17 and the counter electrodes 23 between the array substrate 10 and the counter substrate 12. There columnar spacers 40 maintain the cell gap between the array substrate 10 and the counter substrate 12 at a prescribed value and function also as the auxiliary capacitors.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a liquid crystal display device.

[0002]

2. Description of the Related Art In general, a liquid crystal display element has a pair of substrates each having electrodes formed thereon and facing each other, and a liquid crystal layer is sealed between these substrates.
One set of substrates faces each other with a predetermined gap (cell gap) therebetween, and this cell gap has a significant effect on the display characteristics of the liquid crystal display device. That is, when the cell gap is not uniform over the entire surface of the liquid crystal display element, display quality degradation such as color unevenness, display unevenness, and interference fringes is caused. 2. Description of the Related Art In recent years, as the definition and the capacity of a liquid crystal display element have been increased, it has become necessary to maintain the cell gap with high precision and uniformity over a larger area than before.

Conventionally, in order to keep the cell gap uniform,
Spacer particles are scattered on one substrate, and the other substrate is arranged on this substrate so as to face the substrate. However, there is a problem that the cell gap becomes non-uniform due to variations in the distribution density of the spacers and the lump of the spacers. Further, if the scattered spacers are present on the pixels, there is a problem that the spacers do not function as an optical shutter, thereby causing a decrease in contrast.

Further, when an external force acts by pressing a portion of the spacer having a low scattering density with a finger or the like, the cell gap is significantly reduced, and various problems occur. For example, the liquid crystal alignment (especially the liquid crystal alignment of the smectic layer) is disturbed, the spacer is deformed or broken, and the surrounding alignment film is destroyed.
Display failure may occur due to a short circuit between the opposing substrates, or the glass substrate may be damaged when a thin glass substrate (about 0.7 mm or less in thickness) is used.

To solve such a problem, a liquid crystal display device as disclosed in JP-A-1-134336 has been provided. In this liquid crystal display device, an alignment film is formed on an array substrate having pixel electrodes, wirings, and the like formed in a matrix on the surface, a columnar spacer is formed on the alignment film by photolithography or the like, and then the other substrate is formed. It has a configuration of facing. Since the columnar spacer as described above is formed by photolinography, it is possible to form a non-pixel portion in a desired shape with a uniform distribution density.

[0006]

In the method of dispersing the spacer particles, 90% or more of the dispersed spacer particles fall on the substrate and are used for maintaining the cell gap.
In other words, the same amount of spacer particles as the spacer particles sandwiched between the substrates may be sprayed.

However, when the columnar spacer is formed by photolithography, a photosensitive resin is applied to the entire surface of the substrate, and development is performed after exposure. Then, the photosensitive resin other than the portion where the columnar spacer is formed is dissolved in the developer and discarded. When a 5-micron square columnar spacer is formed in a 100-micron square pixel, about 0.25% of the photosensitive resin applied on the substrate is used as the columnar spacer.
The remaining 99.75% is unused and discarded. As described above, since the efficiency of using the material (photosensitive resin) of the columnar spacer is extremely low, there is a serious problem that the manufacturing cost increases.

On the other hand, in a liquid crystal display device using a thin film transistor (hereinafter, referred to as a TFT), a capacitor called an auxiliary capacitor (Cs: storage capacitor) is formed for each pixel in order to hold and drive liquid crystal molecules. I have. This auxiliary capacitance is composed of a pixel electrode, an auxiliary capacitance line (Cs line), and an insulator sandwiched between them.

The auxiliary capacitance line is drawn out of the liquid crystal cell, like the signal line and the gate line, and has the same potential as the counter electrode on the second substrate facing the first substrate on which the semiconductor switching elements are formed. Is given.

When the auxiliary capacitance line is made thinner in order to improve the aperture ratio of the liquid crystal display element, the amount of charge stored in the auxiliary capacitance decreases. For this reason, the auxiliary capacitance line cannot be made thin, and there is a problem that the aperture ratio is reduced by the auxiliary capacitance line. When an opaque metal wiring such as aluminum or chromium is used as the auxiliary capacitance line in order to lower the wiring resistance, the aperture ratio of the liquid crystal display element is reduced.

Further, there is a problem that the storage capacitor line is short-circuited with the gate line or the signal line to cause display defects.
In particular, the number of intersections between the auxiliary capacitance lines and the signal lines is almost the same as the number of pixels, so that there is a high probability of short-circuiting at these intersections. A short circuit between the auxiliary capacitance line and the signal line is called a CS short circuit, and is a main cause of the failure of the TFT array.

On the other hand, when a pixel electrode is formed on the auxiliary capacitance line, there is a problem that unevenness is formed on the surface of the pixel electrode, and a liquid crystal alignment defect occurs at the step. In particular, as a liquid crystal material, a ferroelectric liquid crystal (FLC) which is a smectic phase, an antiferroelectric liquid crystal (AFLC), a distorted helical ferroelectric liquid crystal (DH)
F), twisted ferroelectric liquid crystal (TF)
When using (LC) or the like, a serious problem occurs.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to eliminate cell gap unevenness, to prevent display failure even when a local force is applied from the outside, and to achieve C-S It is an object of the present invention to provide a liquid crystal display element having a high aperture ratio and good display quality without a short circuit and a short circuit between a gate line and an auxiliary capacitance line.

[0014]

According to a first aspect of the present invention, there is provided a liquid crystal display device comprising: a first substrate having a pixel electrode and a switching element for driving the pixel electrode; A second substrate having electrodes and disposed opposite to the first substrate; and a liquid crystal layer sealed between the first and second substrates, wherein the switching element and the counter electrode face each other. A columnar spacer including a dielectric layer and forming an auxiliary capacitor is provided in the region.

According to a fourth aspect of the present invention, there is provided a liquid crystal display device comprising: a first substrate having a pixel electrode and a switching element electrically connected to the pixel electrode via a source electrode; A second substrate disposed opposite to the first substrate, and a liquid crystal layer sealed between the first and second substrates. A liquid crystal layer is provided in a region where the source electrode and the counter electrode face each other. In addition, a columnar spacer including a dielectric layer and forming an auxiliary capacitance is provided.

According to the liquid crystal display element configured as described above, in the pixel electrode region, a liquid crystal capacitor including a pixel electrode (conductor), liquid crystal molecules (dielectric), and a counter electrode (conductor) is formed. .

The columnar spacer extends between the switching element or the source electrode of the switching element and the counter electrode, maintains a cell gap between the first and second substrates, and has one end contacting the source electrode. Since the other end is in contact with the counter electrode, it also functions as an auxiliary capacitance.

That is, in the region of the switching element provided with the columnar spacer, a column capacitor including a source electrode (conductor), a dielectric layer, and a counter electrode (conductor) is formed. Since the pixel electrode and the source electrode are electrically connected and have the same potential, the column capacitor is connected in parallel with the above-described liquid crystal capacitor. Therefore, the column capacitor, that is, the column spacer acts as an auxiliary capacitance.

Therefore, the auxiliary capacitance line provided for holding and driving the liquid crystal display element becomes unnecessary, and the gate line
Short circuit failure between the auxiliary capacitance lines can be prevented, and the aperture ratio can be significantly increased. In addition, it is not necessary to draw the auxiliary capacitance line to the periphery of the substrate as in the related art,
As a result, the frame of the liquid crystal display element can be narrowed.

Since the auxiliary capacitance line provided on the pixel electrode can be omitted, the pixel electrode can be made flat without unevenness. Therefore, the liquid crystal alignment defect caused by the unevenness of the pixel electrode is eliminated, and the contrast of the liquid crystal display element is improved.

In the present invention, the dielectric layer of the columnar spacer is made of photosensitive polyimide, polyimide, photosensitive acrylic, acrylic, photosensitive epoxy, epoxy, photosensitive benzocyclobutyne polymer, benzocyclobutyne polymer, polyvinylidene fluoride, epoxy It is desirable to use at least one material selected from dielectrics (insulators) such as resins such as acrylates or inorganic substances such as silicon dioxide and silicon nitride.

In the dielectric layer of the columnar spacer, as a ferroelectric substance, a perovskite-type inorganic dielectric such as PZT or PZTL, a Rochelle salt, barium titanate, lead metaniobate, glycine sulfate, potassium nitrate, sodium nitrite, Any of bismuth titanate, lithium tantalate, potassium iodate, and barium magnesium fluoride can be used, and polyvinylidene fluoride (PVDF), a copolymer of vinylidene fluoride and trifluoroethylene as an organic ferroelectric material. Any of a polymer and a copolymer of vinylidene sanide and vinyl acetate can be used.

The conductive layer of the columnar spacer according to the present invention comprises:
Chrome, titanium, aluminum, nickel, copper, gold,
Silver, tungsten, molybdenum, tantalum, indium, tin, indium oxide, indium tin oxide,
It is preferably formed of at least one material selected from iron, cobalt, yttrium, yttrium oxide, graphite, and the like, or a mixed alloy of these materials. By using such a material, a constituent material of the columnar spacer does not dissolve into the liquid crystal, and a highly reliable liquid crystal display element can be provided.

According to the liquid crystal display device of the present invention, at least a part of the columnar spacer is formed by laminating a color filter material. In this case, when forming the color filter on the substrate, at least a part of the columnar spacer can be formed together.
Therefore, the photolithography process for forming the columnar spacer is simplified.

[0025]

Embodiments of the present invention will be described below in detail with reference to the drawings. As shown in FIGS. 1 and 2, an active matrix type liquid crystal display element according to a first embodiment of the present invention includes an array substrate 10 as a first substrate, and an And a liquid crystal layer 14 sealed between these substrates.

The array substrate 10 includes a rectangular transparent glass substrate 33, on which a number of parallel gate lines 32 and a number of signal lines substantially orthogonal to these gate lines are provided. 16 and are formed in a matrix. In each region surrounded by the signal line 16 and the gate line 32, indium tin oxide (hereinafter referred to as ITO)
) Is formed.

At the intersection of each signal line 16 and each gate line 32, an inverted staggered thin film transistor (hereinafter referred to as TFT) 1 using the gate line 32 itself as a gate electrode.
7 are provided.

The TFT 17 will be described in detail. A gate line 32 formed on a glass substrate 33 is covered with a gate insulating film 35 having a laminated structure of a gate oxide film and a silicon oxide film. On top is amorphous silicon (hereinafter a-Si)
A semiconductor thin film 31 composed of a thin film is formed.

On the semiconductor thin film 31, a channel protective film 30 made of a silicon nitride film is formed to protect the semiconductor thin film 31 when forming a channel. On the semiconductor thin film 31 and the channel protective film 30, a source electrode 27 electrically connected to the semiconductor thin film 31 via an ohmic layer 29 and a drain electrode 26 integrated with the signal line 32 are arranged. . Also, the source electrode 27
Are electrically connected to the pixel electrode 28.

The TFT 17 having the above structure is covered with a protective layer 25 of silicon oxide. The protective layer 25, the gate lines 32, the signal lines 16, the pixel electrodes 181 and the like are covered with an alignment film 24 made of polyimide or the like.

On the other hand, the opposite substrate 12 is a transparent glass substrate 2
1, a color filter 22 and a transparent counter electrode 23 made of ITO are sequentially formed over the entire inner surface of the glass substrate. Further, on the counter electrode 23,
A transparent alignment film 20 made of polyimide or the like is formed.

A column spacer 40 is provided between the array substrate 10 and the counter substrate 12 in a region between the source electrode 27 and the counter electrode 23 of each TFT 17. These columnar spacers 40 maintain the cell gap between the array substrate 10 and the counter substrate 12 at a predetermined value, and also function as an auxiliary capacitor, as described later.

More specifically, each columnar spacer 40 is
It has a prismatic column 42 extending substantially perpendicularly from the surface of the counter electrode 23 of the counter substrate 12, and this column is formed of copper as a conductor to a height of 5 microns. The pillar 42 is covered with the alignment film 20 except for the upper end in contact with the counter electrode 23. The extending end of the column 42 is connected to the alignment film 2 on the array substrate 10 side via the alignment film 20.
4 and is opposed to the source electrode 27 of the TFT 17.

Thus, the protective layer 25 of silicon oxide and the alignment films 20 and 24 of polyimide are located between the source electrode 27 of the array substrate 10 and the copper pillar 42 on the counter substrate 12.
Is sandwiched. Since silicon oxide and polyimide are dielectrics, a laminate of the source electrode 27, the silicon oxide protective layer 25, the polyimide alignment films 20, 24, and the copper pillars 42 constitutes a pillar spacer having an auxiliary capacitance function. doing.

Next, a method of manufacturing the liquid crystal display device configured as described above will be described. First, the array substrate 10
A gate line 32 made of a MoTa alloy is formed on the glass substrate 33 by using a magnetron sputtering method, and then a gate insulating film 35 made of a gate oxide film and silicon nitride is formed.

Subsequently, a-Si is formed on the gate insulating film 35.
A film 31 and a channel protection film 30 made of silicon nitride are formed by a CVD method. A-S by etching
After the island of the i film is formed, the ohmic layer 29 is formed.
Thereafter, a pixel electrode 28 is formed in each region, and further, Mo /
A source electrode 27 and a drain electrode 26 made of Al are formed. Thus, the TFT 17 is completed.

Finally, a protective layer 25 of silicon oxide having a thickness of 2500 angstroms is formed on the TFT 17. The protective layer 25 on the source electrode 27 functions as a storage capacitor dielectric.

On the other hand, after forming a color filter 22 on a glass substrate 21, a transparent counter electrode 23 made of ITO is formed on the entire surface of the counter substrate 12. Subsequently, a region other than the portion where the columnar spacer 40 is to be formed is masked with a positive resist having a thickness of 5 μm. In this state, a copper film is formed on the positive resist by a sputtering method, and the copper film is placed in a plating tank containing copper ions and plated. Thereafter, by removing the positive resist, a copper prism 42 having a height of 5 microns is formed.

Subsequently, the array substrate 10 on which the TFT 17 is formed, the color filter 22, the counter electrode 23,
On the counter substrate 12 on which the pillars 42 are formed, the alignment film 24,
A soluble polyimide (AL- manufactured by Nippon Synthetic Rubber Co., Ltd.)
3046) were printed, baked at 80 ° C. for 1 minute using a hot plate, and then further baked in an N 2 oven for 18 minutes.
The solvent is volatilized by baking at 0 ° C. for 30 minutes. The thickness of the formed polyimide was 500 angstroms.

Thereafter, the polyimide films were rubbed to form alignment films 24 and 20. At this time, a rubbing cloth made of rayon and having a hair tip diameter of 0.1 to 10 μm was used in order to sufficiently perform the orientation treatment up to the peripheral portion of each column 42.

Next, an epoxy-based sealing material mixed with a fiber having a diameter of 5 μm is applied to the periphery of the glass substrate 21 of the opposing substrate 12, and then the opposing substrate 12 is arranged to face the array substrate 12. Then, these substrates are accurately aligned, and the two substrates are placed in an oven in a pressurized state.
Heat at 0 ° C. for 3 hours. As a result, the sealing material is completely cured, and the array substrate 10 and the counter substrate 12 are bonded to each other.

In this state, the source electrode 27 of each TFT 17 on the array substrate 10 and the column 4 on the opposite substrate 12
2, a protective layer 25 of silicon oxide and polyimide alignment films 24 and 20 are interposed. Since silicon oxide and polyimide are dielectrics, the source electrode 2
7, silicon oxide protective layer 25, polyimide alignment film 24,
The laminate composed of 20 and the copper pillars 42 constitutes a pillar spacer 40 having an auxiliary capacitance function.

In this embodiment, each columnar spacer 4
Numeral 0 is a square prism having a length of 30 μm, a width of 100 μm, and a height of 5 μm, and constitutes a capacitor having a capacitance of 0.4 pF. Finally,
By injecting a chiral nematic liquid crystal material into the gap between the array substrate 10 and the opposing substrate 12,
An inch TN liquid crystal display element is completed.

The columnar spacers 40 are preferably arranged at a rate of 0.05 to 700 per 1 mm 2. The cross-sectional shape of the columnar spacer 40 parallel to the glass substrate 21 or 33 is preferably a circle or an ellipse, or may be a polygon such as a square, a rectangle, or a triangle.

The present inventors conducted various tests on the liquid crystal display device constructed as described above. At this time, since no spacer was provided on each pixel electrode 28 and the pixel electrode was flat, the alignment of the liquid crystal was uniform and no alignment defect was observed.

The columnar spacer 40 completely functions as an auxiliary capacitor, and has a writing time of 33 μs and a frame period of 1
Good holding drive was possible in 6.7 ms, and an extremely good display image was obtained. Further, the columnar spacers 40 effectively functioned as spacers for maintaining the cell gap, and the cell gap could be maintained with high accuracy of ± 0.05 μ over the entire surface of the liquid crystal display element.

Since the columnar spacer 40 is very hard, even if the center of the liquid crystal display element is strongly pressed with a finger, or 3 kg
/ Cm @ 2 did not affect the display quality at all.

Further, the liquid crystal display element was operated at 70 ° C. and 50% humidity.
As a result of conducting a continuous driving test for 1000 hours under the above environment, nothing dissolves into the liquid crystal from the columnar spacers 40, there is no decrease in the voltage holding ratio or contrast, and good display quality is obtained even after driving for 1000 hours. Was done.

According to the liquid crystal display device configured as described above, the columnar spacers are provided between the source electrode and the counter electrode of each TFT, and these columnar spacers serve as the cell between the array substrate and the counter substrate. The gap is maintained uniform and also functions as an auxiliary capacitor.

For this reason, the conventional auxiliary capacitance line provided for holding and driving the liquid crystal display element becomes unnecessary, so that inconvenience such as short-circuit failure between the gate line and the auxiliary capacitance line can be prevented, and the aperture ratio is significantly increased. Can be. Further, unlike the related art, it is not necessary to draw the auxiliary capacitance line to the peripheral portion of the substrate, so that the frame of the liquid crystal display element can be narrowed.

Since the auxiliary capacitance line provided over the pixel electrode can be omitted, the pixel electrode can be made flat without irregularities. Therefore, the liquid crystal alignment defect caused by the unevenness of the pixel electrode is eliminated, and the contrast of the liquid crystal display element is improved.

Further, since the storage capacitor line becomes unnecessary, the potential applied to the storage capacitor line in the related art becomes unnecessary, so that the power consumption can be reduced accordingly.
Further, an auxiliary capacitance line is not required, and the number of photolithography steps for forming the auxiliary capacitance line can be reduced. The cost of the columnar spacer forming step is higher than that of the conventional step of dispersing the granular spacers.However, since the step of forming the auxiliary capacitance lines can be reduced, the overall manufacturing cost of the liquid crystal display element is reduced by the granular spacer dispersing type. It can be cheaper than a liquid crystal display element.

On the other hand, in order for the columnar spacer to function as an auxiliary capacitor, a part of the columnar spacer needs to be in contact with the pixel electrode or the source electrode. In other words,
Even when the columnar spacer is provided between the pixel electrode and the counter electrode, the columnar spacer can function as an auxiliary capacitor. However, in this case, the following problem occurs.

That is, when the columnar spacer is provided so as to overlap the pixel electrode, the columnar spacer becomes a non-display area, and the aperture ratio decreases. Further, in order to increase the capacity of the columnar spacer, the distance between the pixel electrode and the counter electrode is made shorter than the thickness of the liquid crystal layer, or when a conductor layer is provided on the pixel electrode or the counter electrode, the columnar spacer is used. The electric field spreads around. Then, the liquid crystal molecules are affected by the electric field,
In the peripheral portion of the columnar spacer, that is, in the pixel electrode region, a misalignment region occurs. Such an alignment defect area is visually recognized as light leakage, and as a result, the contrast and display quality of the liquid crystal display element are reduced.

On the other hand, when the columnar spacers are provided in the source electrode region of the TFT as in the liquid crystal display element according to the present embodiment, the aperture ratio does not decrease due to the columnar spacers. Further, even when a liquid crystal alignment defect region is generated around the columnar spacer due to an electric field from the columnar spacer, the contrast and display quality of the liquid crystal display element do not decrease because the source electrode region is a non-display region.

FIG. 3 shows a liquid crystal display device according to a second embodiment of the present invention. The liquid crystal display element according to the present embodiment is different from the above-described first embodiment in that the pillars 42 of each pillar spacer 40 are formed of a laminate of acrylic resin for forming a color filter. doing.

That is, the pillars 42 of each pillar spacer 40
Has a prismatic shape extending substantially perpendicularly from the inner surface of the color filter 22 formed on the counter substrate 12. Then, when the color filter 22 is formed, the pillar 42
It is formed by sequentially stacking red, green, blue, and black acrylic resins.

The column body 42 is covered with the counter electrode 23 made of ITO and the alignment film 20 made of polyimide except for the end on the color filter 22 side. The extending end of the pillar 42 is connected to the TF provided on the array substrate 10 side.
It is located on the source electrode 27 of T17 and is in contact with the alignment film 24 on the array substrate side via the counter electrode 23 and the alignment film 20.

Thus, the protective layer 25 made of silicon oxide and the alignment films 20 and 24 made of polyimide are sandwiched between the source electrode 27 of the array substrate 10 and the pillar 42 on the counter substrate 12. Since silicon oxide and polyimide are dielectrics, the source electrode 27, the silicon oxide protective layer 25, the polyimide alignment films 20, 24, and the pillar 42
Constitute a columnar spacer having an auxiliary capacitance function.

The other structure of the liquid crystal display device is the same as that of the above-described first embodiment, and the same portions are denoted by the same reference characters and will not be described in detail. next,
A method for manufacturing the liquid crystal display device according to the second embodiment configured as described above will be described.

First, the gate lines 3 are formed on the glass substrate 33 of the array substrate 10 in the same manner as in the first embodiment.
2, gate insulating film 35, signal line 16, pixel electrode 28, T
FT17 and the like are formed. Subsequently, a protective layer 25 of silicon oxide having a thickness of 800 Å is formed on the TFT 17. The protective layer 25 on the source electrode 27 functions as a storage capacitor dielectric.

On the other hand, for the opposite substrate 12, a color filter 22 is formed on a glass substrate 21. in this case,
First, an acrylic resist in which a red pigment is dispersed is printed on the glass substrate 21, and a portion where the red color filter and the columnar spacer 40 are to be formed is irradiated with ultraviolet light. Thereafter, the acrylic resist is developed with an organic alkaline developer to remove the resist in the non-exposed areas.

As a result, a red pattern is formed on the glass substrate 21. Subsequently, green, blue, and black patterns are sequentially formed on the glass substrate 21 by the same method, and a color filter 22 including a black matrix is formed.

In the portion where the columnar spacer is formed,
Red, green, blue, and black acrylic resins are sequentially stacked to form a trapezoidal column 42 having a height of 4.5 microns. After that, an ITO film is formed on the color filter 22 and the pillars 42 by sputtering to form a counter electrode 23.

Subsequently, the array substrate 10 on which the TFT 17 is formed, the color filter 22, the counter electrode 23,
On the counter substrate 12 on which the pillars 42 are formed, the alignment film 24,
A soluble polyimide (AL- manufactured by Nippon Synthetic Rubber Co., Ltd.)
1051) were printed, baked at 80 ° C. for 1 minute using a hot plate, and then further baked in
The solvent is volatilized by baking at 0 ° C. for 30 minutes. The thickness of the formed polyimide was 200 angstroms.
After that, the polyimide film is subjected to a rubbing treatment,
20.

Next, an epoxy-based sealing material mixed with a fiber having a diameter of 5 μm is applied to the periphery of the glass substrate 21 of the opposing substrate 12, and then the opposing substrate 12 is arranged to face the array substrate 12. Then, these substrates are accurately aligned, and the two substrates are placed in an oven while being pressed.
Heat at 0 ° C. for 2 hours. As a result, the sealing material is completely cured, and the array substrate 10 and the counter substrate 12 are bonded to each other.

In this state, the source electrode 27 of each TFT 17 on the array substrate 10 and the column 4
2, a protective layer 25 of silicon oxide and polyimide alignment films 24 and 20 are interposed. Since the silicon oxide and the polyimide are dielectrics, the source electrode 27, the silicon oxide protective layer 25, the polyimide alignment film 2
The stacked body including the columns 4 and 20 and the column 42 constitutes a columnar spacer 40 having an auxiliary capacitance function.

In this embodiment, each columnar spacer 4
Numeral 0 is a square pillar having a length of 10 μm, a width of 100 μm, and a height of 5 μm, which constitutes a capacitor having a capacitance of 0.4 pF. Finally,
By injecting a chiral nematic liquid crystal material into a cell gap between the array substrate 10 and the opposing substrate 12, a TN liquid crystal display element having a diagonal of 9 inches is completed.

According to the liquid crystal display device configured as described above, the columnar spacers are provided between the source electrode and the counter electrode of each TFT, and these columnar spacers are provided between the array substrate and the counter substrate. , And also functions as an auxiliary capacitor. Therefore, the same function and effect as those of the first embodiment can be obtained.

Further, according to the second embodiment, since the pillars 42 of each pillar spacer 40 are formed simultaneously with the formation of the color filter, an independent plating step for forming the pillars is required. And productivity can be improved.

FIG. 4 shows a liquid crystal display device according to a third embodiment of the present invention. The liquid crystal display element according to the present embodiment is different from the above-described first embodiment in that the column 42 of each columnar spacer 40 is formed of siloxane containing carbon fine particles.

That is, the pillars 42 of each pillar spacer 40
Is formed in a prismatic shape by using siloxane containing carbon fine particles, extends almost vertically from the inner surface of the alignment film 20 formed on the counter substrate 12, and has an extended end provided on the array substrate 10 side. On the source electrode 27 of the TFT 17 thus formed, it is in contact with the alignment film 24 on the array substrate side.

As a result, the protective layer 25 of silicon oxide and the alignment film 24 of polyimide are sandwiched between the source electrode 27 of the array substrate 10 and the pillar 42 on the counter substrate 12. Since silicon oxide and polyimide are dielectrics, the source electrode 27, the silicon oxide protective layer 2
5, a laminate of the polyimide alignment film 24 and the pillars 42 constitutes a pillar spacer 40 having an auxiliary capacitance function.

The other structure of the liquid crystal display device is the same as that of the above-described first embodiment, and the same portions are denoted by the same reference characters and will not be described in detail. next,
A method for manufacturing the liquid crystal display device according to the third embodiment configured as described above will be described.

First, the gate lines 3 are formed on the glass substrate 33 of the array substrate 10 in the same manner as in the first embodiment.
2, gate insulating film 35, signal line 16, pixel electrode 28, T
FT17 and the like are formed. Subsequently, a 2000-Å-thick silicon oxide protective layer 25 is formed on the TFT 17.
To form The protective layer 25 on the source electrode 27 functions as a storage capacitor dielectric.

On the other hand, as for the counter substrate 12, a color filter 22 and a counter electrode 23 made of ITO are sequentially laminated on a glass substrate 21. Then, the counter substrate 1
2 is printed with soluble polyimide (AL-1051 manufactured by Japan Synthetic Rubber Co., Ltd.) as an alignment film 20, baked at 80 ° C. for 1 minute using a hot plate, and further baked at 180 ° C. for 30 minutes in a N2 oven. To evaporate the solvent. The thickness of the formed polyimide was 600 Å. Thereafter, the polyimide film was subjected to a rubbing treatment to form an alignment film 20.

Next, a polysilane solution dissolved in toluene is applied to the alignment film 20 of the counter substrate 12 and placed in an oven at 120 ° C. for 1 minute to volatilize the toluene, thereby obtaining a thickness of 5.5.
A polysilane film of μ is formed. Then, after irradiating ultraviolet light to a portion of the polysilane film where a columnar spacer is to be formed, the film is developed with a toluene-based developer to remove the resist in a non-exposed portion.

The substrate thus formed is immersed in an alcohol solution containing about 30% of carbon fine particles. As a result, the carbon fine particles are dispersed in the exposed polysilane, and can be made conductive. Subsequently, the substrate is placed in an oven at 180 ° C. for 10 minutes to convert polysilane into siloxane, and immobilize carbon fine particles in siloxane. As a result, the siloxane pillars 42 containing carbon fine particles are formed.

In this embodiment, since the columnar spacer is formed on the rubbed alignment film 20, the columnar body 4 is formed.
The periphery of No. 2 is completely oriented. Then, TF
A soluble polyimide (AL-105 manufactured by Nippon Synthetic Rubber Co., Ltd.) was used as an alignment film 24 on the array substrate 10 on which T17 was formed.
1) is printed and baked at 80 ° C. for 1 minute using a hot plate, and further baked in an N 2 oven at 180 ° C. for 30 minutes to volatilize the solvent. The thickness of the formed polyimide was 600 Å. Thereafter, the polyimide film was subjected to a rubbing treatment to form an alignment film 24.

Next, an epoxy-based sealing material mixed with a fiber having a diameter of 5 μm is applied to the periphery of the glass substrate 21 of the opposing substrate 12, and then the opposing substrate 12 is arranged to face the array substrate 10. Then, these substrates are accurately aligned, and the two substrates are placed in an oven while being pressed.
Heat at 0 ° C. for 2 hours. As a result, the sealing material is completely cured, and the array substrate 10 and the counter substrate 12 are bonded to each other.

In this state, the source electrode 27 of each TFT 17 on the array substrate 10 and the column 4
2, a protective layer 25 of silicon oxide and a polyimide alignment film 24 are interposed. Since silicon oxide and polyimide are dielectrics, the source electrode 2
7, silicon oxide protective layer 25, polyimide alignment film 24,
The stacked body including the siloxane pillars 42 constitutes a pillar spacer 40 having an auxiliary capacitance function.

In this embodiment, each columnar spacer 4
Numeral 0 is a square pillar having a length of 10 μm, a width of 100 μm, and a height of 5 μm, which constitutes a capacitor having a capacity of 0.15 pF. Finally, a chiral nematic liquid crystal material is injected into a cell gap between the array substrate 10 and the opposing substrate 12 to complete a TN liquid crystal display element having a diagonal of 9 inches.

According to the liquid crystal display device configured as described above, the columnar spacers are provided between the source electrode and the counter electrode of each TFT, and these columnar spacers serve as a sail between the array substrate and the counter substrate. The gap is maintained uniform and also functions as an auxiliary capacitor. Therefore, the same function and effect as those of the first embodiment can be obtained.

FIG. 5 shows a liquid crystal display device according to a fourth embodiment of the present invention. This liquid crystal display element differs from the first embodiment in that the column body 42 of each columnar spacer 40 is formed directly on the array substrate 10 side, in particular, on the source electrode 27 of the TFT 17. I have.

That is, the column 42 of each columnar spacer 40
Is formed in a cylindrical shape from aluminum, and extends almost vertically from the source electrode 27 of the TFT 17 provided on the array substrate 10. The pillars 42 are covered with the alignment film 24 made of polyimide except for the end on the source electrode 27 side. The extension end of the column 42 is connected to the alignment film 2 provided on the counter substrate 12 side via the alignment film 24.
0 is in contact.

As a result, the polyimide alignment films 20 and 24 are sandwiched between the opposing substrate 12 and the column 42 extending from the source electrode 27 of the array substrate 10. Since the polyimide is a dielectric, the source electrode 27, the aluminum pillar 42, and the polyimide alignment films 24, 2
0 is a columnar spacer 40 having an auxiliary capacitance function.
Is composed.

The other structure of the liquid crystal display device is the same as that of the above-described first embodiment, and the same portions are denoted by the same reference characters and will not be described in detail. next,
A method for manufacturing the liquid crystal display device according to the fourth embodiment configured as described above will be described.

First, the gate lines 3 are formed on the glass substrate 33 of the array substrate 10 in the same manner as in the first embodiment.
2, gate insulating film 35, signal line 16, pixel electrode 28, T
FT17 and the like are formed.

Subsequently, a region other than the source electrode 27 on the array substrate 10 is masked with a positive resist having a thickness of 5 μm, and the resultant is put into a plating tank containing Al ions to perform plating. Next, the positive resist is peeled off, and a columnar column 42 made of Al having a height of 5 μm and a diameter of 20 μm is formed on the source electrode 27. Then, TF
On T17, a protection layer 25 of silicon oxide having a thickness of 800 Å is formed.

On the other hand, as for the counter substrate 12, a color filter 22 and a transparent counter electrode 23 made of ITO are formed on the glass substrate 21 over the entire surface. Subsequently, a soluble polyimide (manufactured by Nippon Synthetic Rubber Co., Ltd.) AL-3046)
Are printed at 80 ° C. using a hot plate.
After baking for 180 minutes, it was further heated in an N2 oven at 180 ° C for 30 minutes.
Bake for a minute to evaporate the solvent. The thickness of the formed polyimide was 180 angstroms. Thereafter, the polyimide film was subjected to a rubbing treatment to obtain alignment films 24 and 20.

A rubbing cloth made of nylon and having a hair tip diameter of 0.1 to 10 μm was used in order to sufficiently orient the peripheral portion of the column 42. Next, the counter substrate 12
After applying an epoxy-based sealing material mixed with a fiber having a diameter of 5 μm to the periphery of the glass substrate 21 of FIG.
Are arranged to face the array substrate 10. Then, these substrates are accurately positioned, and the two substrates are placed in an oven while being pressed, and heated at 160 ° C. for 3 hours. As a result, the sealing material is completely cured, and the array substrate 10 and the counter substrate 12 are bonded to each other.

In this state, each T of the array substrate 10 is
The polyimide alignment films 24 and 20 are sandwiched between the pillar 42 formed on the source electrode 27 of the FT 17 and the counter electrode 23 on the counter substrate 12. Since the polyimide is a dielectric material, the stacked body including the source electrode 27, the column 42, and the polyimide alignment films 24 and 20 forms a columnar spacer 40 having an auxiliary capacitance function.

In the present embodiment, each columnar spacer 4
Numeral 0 denotes a cylinder having a diameter of 20 microns, which constitutes a capacitor having a capacitance of 0.4 pF. Finally, a chiral nematic liquid crystal material is injected into a cell gap between the array substrate 10 and the opposing substrate 12 to complete a TN liquid crystal display element having a diagonal of 9 inches.

According to the liquid crystal display device configured as described above, the columnar spacer is provided between the source electrode and the counter electrode of each TFT, and the columnar spacer is provided between the array substrate and the counter substrate. , And also functions as an auxiliary capacitor. Therefore, the same function and effect as those of the first embodiment can be obtained.

Further, according to the fourth embodiment, the pillars 42 of each pillar spacer 40 are connected to the source electrode 2 of the TFT 17.
7, the positioning can be performed with high accuracy with respect to the source electrode. Therefore, a decrease in the aperture ratio caused by the columnar spacer can be further reduced, and the contrast and the display quality can be improved.

FIG. 6 shows a liquid crystal display device according to a fifth embodiment of the present invention. The liquid crystal display element according to the present embodiment has a structure in which the pillars 42 of the respective columnar spacers 40 are formed by a laminate of acrylic resin for forming a color filter, and a part of the pixel electrode extends up to the TFT. The third embodiment is different from the first embodiment in that a columnar spacer is arranged on the extension portion.

That is, the column 42 of each columnar spacer 40
Has a prismatic shape extending substantially perpendicularly from the inner surface of the color filter 22 formed on the counter substrate 12. The pillars 42 are formed by sequentially stacking red, green, blue, and black acrylic resins when forming the color filters 22. The column body 42 is formed on the opposite electrode 2 made of ITO except for the end on the color filter 22 side.
3. Covered with an alignment film 20 made of polyimide.

Further, on the side of the array substrate 10, ITO
Each of the pixel electrodes 28 has an extension 28 a extending above the TFT 17. The extending end of the pillar 42 is located on the extending portion 28 a of the pixel electrode 28, and the alignment film 24 on the array substrate side is disposed via the counter electrode 23 and the alignment film 20.
Is in contact with

Thus, the opposing electrode 23 and the polyimide alignment films 20 and 2 are located between the extension 28 a of the pixel electrode 28 located on the TFT 17 and the column 42 on the opposing substrate 12.
4 is sandwiched. Since the polyimide is a dielectric, the laminate of the extension 28a of the pixel electrode 28, the polyimide alignment films 20, 24, and the column 42 constitutes a columnar spacer 40 having an auxiliary capacitance function.

The other structure of the liquid crystal display device is the same as that of the first embodiment described above, and the same portions are denoted by the same reference characters and will not be described in detail. next,
A method for manufacturing the liquid crystal display device according to the fifth embodiment configured as described above will be described.

First, the gate lines 3 are formed on the glass substrate 33 of the array substrate 10 by the same method as in the first embodiment.
2. The gate insulating film 35, the signal line 16, the TFT 17 and the like are formed. Subsequently, a protective layer 25 of silicon oxide having a thickness of 800 Å is formed on the TFT 17.

Thereafter, a pixel electrode 28 made of ITO is formed on the gate insulating film 35. At this time, a part of the pixel electrode 28 is also formed on the TFT 17 to form the extension 28a. On the other hand, for the counter substrate 12, a color filter 22 is formed on a glass substrate 21. In this case, first, an acrylic resist in which a red pigment is dispersed is printed on the glass substrate 21, and a portion where the red color filter and the columnar spacer 40 are to be formed is irradiated with ultraviolet light. Thereafter, the acrylic resist is developed with an organic alkaline developer to remove the resist in the non-exposed areas.

As a result, a red pattern is formed on the glass substrate 21. Subsequently, green, blue, and black patterns are sequentially formed on the glass substrate 21 by the same method, and a color filter 22 including a black matrix is formed.

In addition, in the portion where the columnar spacer is formed,
Red, green, blue, and black acrylic resins are sequentially stacked to form a trapezoidal column 42 having a height of 3.5 microns. After that, an ITO film is formed on the color filter 22 and the pillars 42 by sputtering to form a counter electrode 23.

Subsequently, on the array substrate 10 on which the TFT 17 is formed, the color filter 22, the counter electrode 2
3. An alignment film 2 is formed on the opposite substrate 12 on which the pillars 42 are formed.
Soluble polyimide (A manufactured by Nippon Synthetic Rubber Co., Ltd.)
L-1051) was printed and baked at 80 ° C. for 1 minute using a hot plate, and then baked at 180 ° C. for 30 minutes in a N2 oven to evaporate the solvent. The thickness of the formed polyimide was 500 angstroms. After that, the polyimide film is subjected to a rubbing treatment so that the alignment film 2 is formed.
4, 20.

Next, an epoxy-based sealing material mixed with a fiber having a diameter of 5 μm is applied to the periphery of the glass substrate 21 of the opposing substrate 12, and the opposing substrate 12 is arranged so as to face the array substrate 12. Then, these substrates are accurately aligned, and the two substrates are placed in an oven while being pressed.
Heat at 0 ° C. for 2 hours. As a result, the sealing material is completely cured, and the array substrate 10 and the counter substrate 12 are bonded to each other.

In this state, each T of the array substrate 10 is
Between the extension 28a of the pixel electrode 28 formed on the FT 17 and the column 42 on the counter substrate 12, the counter electrode 23 and the polyimide alignment films 24 and 20 are sandwiched. And
Since polyimide is a dielectric, a laminate composed of the extended portions 28a, the polyimide alignment films 24 and 20, and the pillars 42 forms a pillar spacer 40 having an auxiliary capacitance function.

In the present embodiment, each columnar spacer 4
0 is a square prism having a height of 15μ, a width of 15μ, and a height of 3.5μ,
A capacitor having a capacitance of 0.1 pF is formed. Finally, a chiral nematic liquid crystal material is injected into a cell gap between the array substrate 10 and the opposing substrate 12 to complete a TN liquid crystal display element having a diagonal of 9 inches.

According to the liquid crystal display device configured as described above, the columnar spacer is provided between the extension of the pixel electrode extending on each TFT and the counter electrode, and these columnar spacers are arranged in an array. The sail gap between the substrate and the counter substrate is maintained uniform, and also functions as an auxiliary capacitor. The columnar spacer is a non-display area TFT
Since it is provided above, it is possible to obtain the same operation and effect as in the first embodiment described above.

Further, according to the fifth embodiment, since the pillars 42 of each pillar spacer 40 are formed simultaneously with the formation of the color filters, an independent plating step for forming the pillars is required. And productivity can be improved.

In the fifth embodiment, the column 42 of the columnar spacer 40 is not limited to the laminate of the color filter material, but may be made of copper or carbon particles as in the first or third embodiment. It may be formed of a conductor such as siloxane contained therein.

The present invention is not limited to the above-described embodiment, but can be variously modified within the scope of the present invention. For example, in the above-described embodiment, a thin film transistor is used as a switching element. However, the present invention is not limited to this, and another switching element such as a thin film diode may be used.

[0113]

As described in detail above, according to the present invention,
By arranging the columnar spacer functioning as an auxiliary capacitor for holding the voltage applied to the pixel electrode on the switching element, the cell gap can be maintained uniform even when an external force acts, and the aperture ratio and contrast can be reduced. A high-quality liquid crystal display element with good display quality can be provided at low cost.

[Brief description of the drawings]

FIG. 1 is a plan view showing an array substrate of a liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of the liquid crystal display element according to the above embodiment.

FIG. 3 is a sectional view of a liquid crystal display device according to a second embodiment of the present invention.

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

FIG. 5 is a sectional view of a liquid crystal display device according to a fourth embodiment of the present invention.

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Array substrate 12 ... Counter substrate 14 ... Liquid crystal layer 16 ... Signal line 17 ... Thin film transistor 20, 24 ... Alignment film 22 ... Color filter 23 ... Counter electrode 25 ... Protective film 26 ... Drain electrode 27 ... Source electrode 28 ... Pixel electrode 28a ... Extension part 30 ... Channel protective film 32 ... Gate line 35 ... Gate insulating film 40 ... Column spacer 42 ... Column

Claims (9)

[Claims] A first substrate having a pixel electrode and a switching element for driving the pixel electrode; a second substrate having a counter electrode disposed opposite to the first substrate; A liquid crystal layer sealed between the second substrates, and in a region where the switching element and the counter electrode face each other,
A liquid crystal display device comprising a columnar spacer including a dielectric layer and forming an auxiliary capacitor. 2. The pixel electrode according to claim 1, wherein said pixel electrode has an extension extending above said switching element, and said columnar spacer is provided between said extension and said counter electrode. Item 2. A liquid crystal display device according to item 1. 3. The opposing substrate includes a color filter provided so as to oppose an opposing electrode, and the columnar spacer extends from the color filter and is formed by laminating a color filter material. 3. The liquid crystal display device according to claim 2, wherein an extension end of the column is in contact with an extension of the pixel electrode via a dielectric layer. 4. A first substrate having a pixel element and a switching element electrically connected to the pixel electrode via a source electrode, and a first substrate having a counter electrode and disposed opposite to the first substrate. And a liquid crystal layer sealed between the first and second substrates. A column spacer including a dielectric layer and forming an auxiliary capacitor in a region where the source electrode and the counter electrode face each other. A liquid crystal display device comprising: 5. The columnar spacer has a columnar body extending from the counter electrode and formed of a conductor, and an extended end of the columnar body is connected to the source electrode via a dielectric layer. The liquid crystal display element according to claim 4, wherein the liquid crystal display element is in contact with the liquid crystal display element. 6. A method according to claim 1, wherein said columnar spacer includes a column having one end in contact with said source electrode via a dielectric layer and another end in contact with said counter electrode via a dielectric layer. 5. The liquid crystal display device according to claim 4, wherein: 7. The columnar spacer has a columnar body extending from the source electrode and formed of a conductor, and an extended end of the columnar body is connected to the counter electrode via a dielectric layer. The liquid crystal display element according to claim 4, wherein the liquid crystal display element is in contact with the liquid crystal display element. 8. The opposing substrate includes a color filter provided to oppose an opposing electrode, and the columnar spacer extends from the color filter and is formed by laminating a color filter material. 5. An extended end of the pillar is in contact with the source electrode via a dielectric layer.
3. The liquid crystal display device according to item 1. 9. The dielectric layer according to claim 1, wherein the dielectric layer includes an alignment film covering the switching element and the pixel electrode, and an alignment film covering the counter electrode. 2. The liquid crystal display device according to claim 1.