JP2003114449A - Active matrix liquid crystal display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize an active matrix liquid crystal display performing high quality display by heightening the degree of freedom for sticking together of a counter substrate disposed, via a liquid crystal layer, opposite to an insulation substrate on which thin film transistors, are disposed in an array shape. SOLUTION: A color filter layer 115 constituted of colored insulation films 118, 116 and 117 of red, green and blue is provided so as to come into contact with an insulation substrate 101 on which the thin film transistor 102 is disposed and a pixel electrode 109 is provided so as to come into contact with the color filter layer 115 and to be conductively connected to a drain 105. The counter substrate 112 having a common electrode 113 provided on the entire surface thereof is stuck to the insulation substrate 101 opposite to each other without performing strict alignment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure technology of an active matrix liquid crystal display device using a thin film transistor or a diode as a switching element.

[0002]

2. Description of the Related Art An active matrix liquid crystal display device is widely used as a display device of a portable device by taking advantage of its features such as high image quality, thinness and light weight. In particular, in order to deal with image display in OA equipment, televisions, etc., full-color display is indispensable, and a display device having the structure shown in FIG. 2 has been devised and put into practical use.

FIG. 2 is a sectional view of a color active matrix liquid crystal display device, in which thin film transistors 202 are arranged in an array on an insulating substrate 201 such as glass. The thin film transistor 202 includes a source 203, a semiconductor layer 204, a drain 205, and a gate electrode 207 that also serves as a gate insulating film 206 scanning line.
The scanning signal applied to 07 controls the current flowing between the source 203 and the drain 205 to act as a switching element. A data line 208 is provided so as to be conductively connected to the source 203 and orthogonal to the scanning line, and a data signal applied to the data line 208 is supplied to the pixel electrode 209 conductively connected to the drain 205 by switching operation of the thin film transistor. Apply. The insulating film 210 maintains insulation between the scanning line and the data line 208 provided so as to be orthogonal to the scanning line. The counter substrate 212 is disposed so as to face the insulating substrate 201 with the liquid crystal layer 211 interposed therebetween, and the pixel electrode 2
The alignment state of the liquid crystal layer 211 is controlled by the electric field generated between the data signal applied to 09 and the common electrode 213 to display information. Counter substrate 2 to realize color display
A red (R), green (G), and blue (B) color filter layer 214 is provided between the pixel electrode 12 and the common electrode 213 at a position corresponding to the pixel electrode 209.

[0004]

However, in the active matrix liquid crystal display device, since the thin film transistor 202 and the color filter layer 214 are arranged on different substrates, there is a problem that the degree of freedom in assembling the liquid crystal display device is low. is there. For example, if the thin film transistor 202 that controls blue data and the pixel electrode 210 are displaced to the left or right, adjacent edges or red colors are mixed and displayed, and accurate color information cannot be displayed. In order to avoid this, the pixel electrode is made smaller than the area of the color filter for each color to ensure the degree of freedom in assembly. As a result, the area for displaying information is reduced and the display quality is degraded.

In view of the above problems, the object of the present invention is to
An object of the present invention is to realize an active matrix liquid crystal display device that increases the degree of freedom in assembling the liquid crystal display device and displays accurate color information with high quality.

[0006]

Means for Solving the Problems In order to solve the above problems, means taken in an active matrix liquid crystal display device according to the present invention include a thin film switching element composed of a thin film transistor or a diode, a colored insulating film, a thin film switching element and a conductive film. That is, the connected pixel electrodes are sequentially laminated.

As another means, a scanning line conductively connected to the gate electrode of the thin film transistor, a colored insulating film, a signal line conductively connected to the source of the thin film transistor, and a pixel electrode conductively connected to the drain of the thin film transistor are sequentially laminated.

As another means, a scanning line conductively connected to the gate electrode of the thin film transistor, a first colored insulating film, a signal line conductively connected to the source of the thin film transistor, a second colored insulating film, and a pixel conductively connected to the drain of the thin film transistor. That is, the electrodes are sequentially laminated.

As another means, a thin film switching element composed of a thin film transistor or a diode, a pixel electrode,
That is, a colored insulating film is sequentially stacked.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

(Embodiment 1) FIG. 1 is a sectional view of an active matrix liquid crystal display device according to Embodiment 1 of the present invention. Thin film transistors 102 are arranged in an array on an insulating substrate 101 such as quartz or glass. Thin film transistor 1
Reference numeral 02 denotes a source 103 and a drain 105 made of a semiconductor containing impurities serving as donors or acceptors, a semiconductor layer 104 made of a semiconductor containing a low concentration of impurities or an intrinsic semiconductor, and a gate insulating film made of an insulator such as silicon oxide. 106, a gate electrode 107 made of a conductive material containing a metal or a high concentration of impurities and also serving as a scanning line. Although the coplanar type thin film transistor is shown in FIG. 1, an inverted stagger type thin film transistor may be used. A data line 108 made of metal is provided so as to be conductively connected to the source 103 and orthogonal to the scanning line. At this time, an interlayer insulating film 110 made of an inorganic insulating film such as silicon oxide or an organic insulating film such as polyimide is provided in order to maintain the insulation between the scanning line and the data line 108. A color filter layer 115 including a red colored insulating film 118, a green colored insulating film 116, and a blue colored insulating film 117 is formed in a thickness of 0.5 to 3 μm so as to be in contact therewith. For the color filter layer 115, a contact hole 119 and a color filter pattern are simultaneously formed by a photolithography method using a colored resist in which a pigment is uniformly dispersed in a PVA-based or acrylic-based photosensitive resin. This is repeated for the three colors of red, green and blue to provide the color filter layer 115 in which the three primary colors are arranged. As the pigment, red may be dianthraquinone type, green may be halogenated phthalocyanine type, and blue may be phthalocyanine type. In order to obtain excellent color reproducibility, a yellow pigment, a purple pigment or the like may be added. The contact hole 120 is
Open at the same time as the source side contact hole 121,
The contact hole 119 of the color filter layer 115 is opened as a mask. A pixel electrode 109 made of a transparent conductive film such as ITO is provided so as to be in contact with the color filter layer 115 and be conductively connected to the drain 105. The data line 108 and the scanning line are formed by the color filter layer 11 having a large film thickness.
Since it is below 5, it is not necessary to provide a space between the data line 108, the scanning line and the pixel electrode 109 as in the conventional case, and the area of the pixel electrode 109 can be increased.

3 to 10 μm so as to face the insulating substrate 101
The counter substrate 112 is attached via the liquid crystal layer 111 having a thickness of m. A common electrode 113 made of a transparent conductive film such as ITO is provided on the entire surface of the counter substrate 112. Counter substrate 112
Since it has a simple structure in which the common electrode 113 is simply provided, there is no need to perform any particular alignment when assembling the liquid crystal display device, and the degree of freedom in assembly is high. Furthermore, the common electrode 112
Is a low-resistance IT because there is no thermal restriction during ITO film formation.
O can be obtained and can be fixed at a constant potential all the time, so that a large liquid crystal display device without flicker can be realized.

As a method for forming the color filter layer 115, the color resist method has been described as an example. However, the silver salt sensitive material used for the color film is applied to obtain a three primary color pattern by one exposure. Method, offset printing, flexographic printing, or other printing method is used to form the color filter layer, and the photolithography method is used to form the contact holes 11.
If 9 is opened, it can be realized by a simpler process.

(Embodiment 2) FIG. 3 is a sectional view of an active matrix liquid crystal display device according to Embodiment 2 of the present invention, in which a diode is used as a switching element. The diodes 302 are arranged in an array on an insulating substrate 301 such as glass. The diode 302 is an MIM element in which a first metal 303 made of tantalum, an insulating layer 304 made of tantalum oxide, and a second metal 305 made of a metal such as chromium are stacked. It is a non-linear resistance element that utilizes the flowing Pool-Frenkel current. A color filter layer 311 including a red colored insulating film 308, a green colored insulating film 309, and a blue colored insulating film 310 is provided so as to be in contact with these. As in the first embodiment, the color filter layer 311 may be formed by any of a colored resist method, a silver salt sensitive material method, and a printing method. The pixel electrode 306 is electrically connected to the second metal 305 through the contact hole 312 opened in the color filter layer 311, and the pixel electrode 306 is connected to the color filter layer 31.
It is formed so as to contact the top of 1. A counter substrate 314 is attached so as to face the insulating substrate 301 through a liquid crystal layer 313 having a thickness of 3 to 10 μm. A data line 315 made of a transparent conductive film such as ITO processed into a stripe shape is provided on the counter substrate 314. The data line 315 is arranged so as to be orthogonal to the scanning line wired at the same time as the first metal 303 of the MIM element, and the data signal applied to the data line 315,
The MIM element is switched by controlling the scanning signal applied to the scanning line, and the pixel electrode 306 and the data line 31 are switched.
An electric field is generated during 5 to control the alignment state of the liquid crystal layer 313 and display information. Since the MIM element and the liquid crystal layer 313 are connected in series at the intersection of the data line 315 and the scanning line, the scanning signal may be applied to the data line and the data signal may be applied to the scanning line, contrary to the upper part. Since the color filter layer 311 is provided below the pixel electrode 306, full-color display is possible, and the MIM element has a color filter layer 31.
Since it is below 1, the area of the pixel electrode 306 can be made larger than in the conventional case, and the transmittance can be greatly improved. Further, unlike the conventional case, it is not necessary to perform strict alignment in the XY directions when assembling the liquid crystal display device, and only one of the alignments is required, and the degree of assembly freedom can be increased.

As the diode, the MIM element having the insulating layer of tantalum oxide has been described, but the MIM element having the insulating layer of silicon nitride, the ZnO varistor, the MIS.
A diode having a structure may be used.

(Embodiment 3) FIG. 4 is a sectional view of an active matrix liquid crystal display device according to Embodiment 3 of the present invention. Here, the configuration of the thin film transistors 402 arranged in an array in the active matrix liquid crystal display device of the present example is the same as that of the active matrix liquid crystal display device shown in FIG. Will be omitted.

As shown in FIG. 4, the thin film transistor 402
A color filter layer 415 including a red colored insulating film 418, a green colored insulating film 416, and a blue colored insulating film 417 is formed so as to be in contact with the above. Color filter layer 4
Reference numeral 15 simultaneously forms a color filter pattern and two contact holes 419 and 420 using a colored resist. The data line 408 and the drain 1 are conductively connected to the source 103 and are in contact with the upper portion of the color filter layer 415.
The pixel electrode 409 is provided so as to be conductively connected to the pixel electrode 05 and contact the upper portion of the color filter layer 415. The data lines 408 and the scanning lines formed at the same time as the gate electrodes 107 are arranged so as to be orthogonal to each other.
15 also serves. With such a structure, there is no need to form an interlayer insulating film provided for the purpose of maintaining insulation between the wirings, and the process can be shortened.

The liquid crystal layer 41 faces the insulating substrate 401.
The counter substrate 41 having the common electrode 413 provided on the entire surface via
Place 2. At this time, it is not necessary to align the counter substrate 412 with the insulating substrate 401, and the degree of freedom in assembling the liquid crystal display device is high. (Embodiment 4) FIG. 5 is a sectional view of an active matrix liquid crystal display device according to Embodiment 4 of the present invention. Here, since the configuration of the thin film transistors 502 arranged in an array in the active matrix liquid crystal display device of this example is similar to that of the active matrix liquid crystal display device shown in FIG. 3, corresponding parts are designated by the same reference numerals. The description is omitted.

As shown in FIG. 4, contact holes 530 and 531 are opened in the gate insulating film 106 on the source 103 and the drain 105, respectively, and the thin film transistor 50 is formed.
2. A red colored insulating film 516 is provided using a colored resist in which a red pigment is dispersed so as to be in contact with the insulating substrate 501.
At this time, by the photolithography method, the source of one thin film transistor at the same time as the color filter pattern,
Contact holes 532 and 533, respectively, in the drain
A total of three contact holes 534 are opened in the source of the adjacent thin film transistor. Next, a blue colored insulating film 517 is provided using a colored resist in which a blue pigment is dispersed. At this time, two contact holes 535 and 536 are opened simultaneously with the color filter pattern. The data line 508 is in contact with the red colored insulating film 516 and the blue colored insulating film 517 and is conductively connected to the source 103.
And a green colored insulating film 518 is provided using a colored resist in which a green pigment is dispersed. Green colored insulating film 51
Reference numeral 8 is provided so as to open a contact hole 537 at the same time as a color filter pattern by a photolithography method and cover all the data lines 508. Here, red,
Although the color insulating film is formed in the order of blue and green and the color filter layer 515 including three primary colors is provided, the color order of the color insulating film to be formed is not limited to this and may be arbitrary.
After forming the colored insulating films of arbitrary two colors, the data lines are wired, and the remaining one color may be formed so as to completely cover the data lines. A pixel electrode 509 is provided so as to be in contact with these and be conductively connected to the drain 105. Scan lines, data lines, and thin film transistors 5 formed simultaneously with the gate electrode 107
Since all 01 are embedded under or inside the color filter layer, the pixel electrode 509 can have a large area without any restrictions such as providing a space between them. Furthermore,
Since the data line 508 provided so as to be orthogonal to the scanning line is provided inside the color filter layer, there is no need to particularly provide an interlayer insulating film for holding insulation between wirings, and the structure is simple. Become. Although the formation of the color filter layer by the colored resist method has been described as an example, the same structure can be realized without any problems even by a forming method by a combination of a printing method and a photolithography method or a forming method by a dyeing method.

The liquid crystal layer 51 is arranged so as to face the insulating substrate 501.
A counter substrate 51 having a common electrode 513 provided on the entire surface via
Place 2. Similar to the first and third embodiments, it is not necessary to align the counter substrate 512 with the insulating substrate 501, and the degree of freedom in assembling the active matrix liquid crystal display is high.

(Embodiment 5) FIG. 6 is a sectional view of an active matrix liquid crystal display device according to Embodiment 5 of the present invention. Here, since the configuration of the thin film transistors 602 arranged in an array in the active matrix liquid crystal display device of this example is similar to that of the active matrix liquid crystal display device shown in FIG. 1, corresponding parts are designated by the same reference numerals. The description is omitted.

As shown in FIG. 6, a pixel electrode 609 is provided so as to be conductively connected to the drain 105, and the thin film transistor 6 is formed.
02, the color filter layer 61 formed of a red colored insulating film 618, a green colored insulating film 616, and a blue colored insulating film 617 so as to be in contact with the data line 108 and cover all of them.
5 is formed. Since the color filter layer 615 does not need to be finely processed such as a contact hole and only a color filter pattern is formed, a printing method such as offset printing or flexographic printing, a silver salt sensitive material method for obtaining a three primary color pattern by one exposure Are suitable.

The liquid crystal layer 61 faces the insulating substrate 601.
The counter substrate 61 in which the common electrode 613 is provided on the entire surface via
Place 2. At this time, similarly to Embodiments 1, 3, and 4, it is not necessary to align the counter substrate 612 with the insulating substrate 601, and the degree of freedom in assembling the liquid crystal display device is high. Further, since the common electrode 613 and the data line 108 or the pixel electrode 609 and the common electrode 613 are not short-circuited even if a conductive foreign substance is mixed in the liquid crystal layer 611, a large active matrix liquid crystal having a large display area. This is advantageous for display devices.

In the active matrix liquid crystal display device having such a structure, the color filter layer 615 is provided between the pixel electrode 609 and the common electrode 613.
Although a sufficient electric field is not applied to the liquid crystal layer 611, a sufficient electric field can be applied to the liquid crystal layer 611 by increasing the voltage of the data signal applied to the data line 108, and information can be displayed without any problem.

In this example, the active matrix liquid crystal display device in which the thin film transistors are arranged in an array has been described, but the same applies to the active matrix liquid crystal display device in which the diodes are arranged in an array in Embodiment 2.

[0026]

The present invention has the following excellent effects.

First, it is not necessary to strictly bond the insulating substrate, in which thin film switching elements composed of thin film transistors or diodes are arranged in an array, to the counter substrate, and the yield at the time of bonding is greatly improved. .

Secondly, since an ITO film can be formed on the electrodes provided on the counter substrate without thermal restriction, an ITO film having a low resistance can be obtained, and an active matrix liquid crystal display device having a large area without flicker can be obtained. realizable.

Third, since the area of the pixel electrode can be increased, a bright image with high transmittance can be realized.

Fourthly, since the color filter layer also serves as the insulation of the intersection of the data line and the scanning line, the conventionally provided interlayer insulating film becomes unnecessary, and the process can be shortened. As a result, yield improvement and cost reduction can be realized.

Fifth, by embedding the data lines in the colored insulating films of the three primary colors forming the color filter layer, it is possible to eliminate the conventional interlayer insulating film and increase the area of the pixel electrode at the same time. A liquid crystal display device with high image quality can be realized at low cost.

Sixth, by providing the color filter layer so as to be in contact with the pixel electrode, the common electrode and the data line or the common electrode and the pixel electrode can be short-circuited even if a conductive foreign substance is mixed in the liquid crystal layer. Since it is not provided, the yield can be improved in the assembly process, and a liquid crystal display device having a large display area can be stably assembled.

[Brief description of drawings]

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

FIG. 2 is a sectional view of a conventional active matrix liquid crystal display device.

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

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

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

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

[Explanation of symbols]

101, 201, 301, 401, 501, 601 Insulating substrate 102, 202, 402, 502, 602 Thin film transistor 302 Diode 103, 203 Source 104, 204 Semiconductor layer 105, 205 Drain 106, 206 Gate insulating film 107, 207 Gate electrode 108 , 208, 315, 408, 508 Data line 109, 209, 306, 409, 509, 609 Pixel electrode 303 First metal 304 Insulation layer 305 Second metal 110, 210 Interlayer insulation film 111, 211, 313, 411 511,611 Liquid crystal layers 112,212,314,412,512,612 Counter substrates 113,213,413,513,613 Common electrodes 115,214,311,415,515,615 Color filter layers 116,309,416,518 ， 16 green colored insulating film 117,310,417,517,617 blue colored insulating film 118,308,418,516,618 red colored insulating film 119,120,121,312,419,420,5
32,533,534,535,536,537 Contact hole

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[Procedure amendment]

[Submission date] July 24, 2002 (2002.7.2)
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[Procedure Amendment 1]

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[Claims]

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[0006]

In order to solve the above problems, an active matrix liquid crystal display device according to the present invention is an active matrix liquid crystal display device in which thin film switching elements composed of thin film transistors are arranged in an array. The thin film switching element is arranged corresponding to the pixel area defined by the signal line,
A pixel electrode conductively connected to the thin film switching element is provided, and a color filter layer color-coded by a plurality of colored insulating films containing at least three colors of red, green and blue is provided on the pixel electrode on the pixel electrode, The color filter layer is characterized in that ends of adjacent colored insulating films are in contact with each other at least outside the pixel electrode formation region. With such a configuration, it is not necessary to perform strict alignment at the time of bonding the array substrate having the thin film switching elements arranged in an array with the counter substrate, and the yield is significantly improved. Further, I provided under the color filter layer
Since the TO film is formed without being subjected to thermal restrictions, it has an effect of reducing the resistance.

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[Procedure Amendment 5]

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[Procedure correction 6]

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ITO provided under the color filter layer
Since the film is formed without thermal constraints,
It has the effect of achieving low resistance. Therefore, it is possible to realize an active matrix liquid crystal display device having a large area without flicker.

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Claims (5)

[Claims] 1. An active matrix liquid crystal display device in which thin film switching elements comprising thin film transistors or diodes are arranged in an array, wherein the thin film switching element, a colored insulating film, and pixel electrodes conductively connected to the thin film switching element are sequentially laminated. An active matrix liquid crystal display device characterized by: 2. A scanning line conductively connected to a gate electrode of a thin film transistor, a colored insulating film, a signal line conductively connected to a source of the thin film transistor, and a pixel electrode conductively connected to a drain of the thin film transistor. Active matrix liquid crystal display device. 3. A scanning line conductively connected to a gate electrode of a thin film transistor, a first colored insulating film, a signal line conductively connected to a source of the thin film transistor, a second colored insulating film, and a pixel conductively connected to a drain of the thin film transistor. An active matrix liquid crystal display device characterized in that electrodes are sequentially laminated. 4. An active matrix liquid crystal display device characterized in that a thin film switching element composed of a thin film transistor or a diode, a pixel electrode and a colored insulating film are sequentially laminated. 5. The pixel region defined by the scanning line and a signal line provided so as to be orthogonal to the scanning line according to claim 1, claim 2, claim 3 or claim 4, An active matrix liquid crystal display device, characterized in that each is color-coded by a plurality of colors including at least three colors of red, green and blue.