JPH11326944A - Liquid crystal display device and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the display quality, the aperture ratio, and the yield by providing an insulating light shielding film in regions corresponding to upper parts of switching elements, area between picture element electrodes, and regions under peripheral edge parts of picture element electrodes in an inter-layer insulating film. SOLUTION: With respect to an active matrix substrate 9, switching elements (for example, thin film transistors TFTs) arranged like a matrix, a gate wiring (scanning signal lines) to send a gate signal to each switching element, and a source wiring (data signal lines) to send a source signal (data signal) are provided on an insulating substrate 1. An inter-layer insulating film 5 is provided so as to cover switching elements, the gate wiring, and the source wiring 4. Picture element electrodes 8 are provided on the inter-layer insulating film 5. A light shielding layer 7 is provided in areas corresponding t upper parts of TFTs, area between picture element electrodes 8, and areas under peripheral edge parts of picture element electrodes 8 is the inter-layer insulating film 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquid crystal display device and a method for manufacturing the same. More specifically, the present invention relates to a liquid crystal display device having excellent display quality, a high aperture ratio, and an excellent yield, and a simple and inexpensive method for manufacturing such a liquid crystal display device.

[0002]

2. Description of the Related Art In recent years, liquid crystal display devices have been widely used from AV to amusement fields, mainly for computer displays. In the future, in order to respond to a variety of media, liquid crystal display devices will become larger, higher definition,
Higher brightness is desired.

FIG. 5 is a sectional view of a conventional active matrix type liquid crystal display device. This liquid crystal display device 500
Are the active matrix substrate 509 and the opposing substrate 51
2 and a liquid crystal layer 513 provided between the active matrix substrate 509 and the counter substrate 512. The active matrix substrate 509 is an insulating substrate 501
And a thin film transistor (TFT) provided on the insulating substrate for controlling electro-optical characteristics of liquid crystal of a liquid crystal layer 513.
(Not shown); a gate wiring (not shown) for supplying a gate signal to the TFT and a source wiring 5 for supplying a source signal to the TFT.
04; an interlayer insulating film 505 provided so as to cover the TFT, the gate wiring and the source wiring; and the interlayer insulating film 50
5 and a pixel electrode 508 provided on the pixel electrode 5. The counter substrate 512 includes an insulating substrate 501; a color filter 510 having color layers R, G, and B and a light-shielding film (black matrix) 507; and a counter electrode 511.

Such a liquid crystal display device provides display information on a screen by selecting display pixels arranged in a matrix. In a liquid crystal display device of this active matrix driving method (a method of selecting a display pixel using a switching element such as a TFT for each pixel electrode 508), a TFT is applied between the pixel electrode 508 and the counter electrode 511. It has a function of turning on and off a signal voltage, and displays image information by optical modulation of a liquid crystal layer caused by a potential difference between a pixel electrode and a counter electrode.

In such a liquid crystal display device, a gate wiring, a source wiring, a TFT, and a pixel electrode are provided via an interlayer insulating film 505. Therefore, since the gate wiring and the source wiring and the pixel electrode can be formed so as to overlap with each other, the area of the pixel electrode can be increased, and as a result, the aperture ratio is increased.

Further, in order to reduce the margin for bonding the substrates and to improve the aperture ratio, a technique has been proposed in which gate and source wirings are used as a light-shielding film (Japanese Patent Laid-Open No. 2-207222).

[0007]

However, the prior art has the following problems.

In the liquid crystal display device shown in FIG. 5, it is very difficult to position the light shielding film when bonding the substrates. For this reason, a large margin for bonding the substrates has to be taken, and an advanced bonding technique is required.
Further, in this liquid crystal display device, since the signal wiring and the pixel electrode are formed via the interlayer insulating film, the SD
Leakage is unlikely to occur, but DD leakage between pixel electrodes tends to occur due to poor patterning due to dust or the like.

In the technique described in Japanese Patent Application Laid-Open No. 2-207222, since the wiring is formed of metal to shield light, there is a reduction in contrast due to reflection from the wiring. Further, in this technique, it is necessary to overlap the signal wiring and the pixel electrode. In a structure where the signal wiring and the pixel electrode do not overlap,
This is because light leakage occurs due to disturbance of the alignment of the liquid crystal due to the lateral electric field of the pixel electrode, which causes a decrease in contrast. When the signal wiring and the pixel electrode are formed so as to overlap with each other, crosstalk occurs due to the coupling capacitance generated therefrom. When the source wiring is formed from a transparent film such as ITO to simplify the manufacturing process, light cannot be shielded.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a liquid crystal display device which is excellent in display quality, has a high aperture ratio, and is excellent in yield. It is an object of the present invention to provide a simple and inexpensive manufacturing method of a liquid crystal display device.

[0011]

A liquid crystal display device according to the present invention has a plurality of scanning signal lines and data signal lines provided crossing each other, switching elements provided in a matrix, and pixel electrodes. An active matrix substrate; a counter substrate having a color filter and a counter electrode; and a liquid crystal layer disposed between the active matrix substrate and the counter substrate. An interlayer insulating film made of a transparent organic resin is provided on the signal line and the switching element; a pixel electrode is provided on the interlayer insulating film except for a region corresponding to the upper part of the switching element; An insulating light-shielding film is provided in a region of the insulating film corresponding to an upper portion of the switching element, a region between the pixel electrodes, and a region below a peripheral portion of the pixel electrode.

In a preferred embodiment, the data signal line is formed of a transparent material.

According to another aspect of the present invention, a method for manufacturing a liquid crystal display device is provided. The method includes the steps of forming a scanning signal line, a data signal line, and a switching element on a substrate; and forming an interlayer insulating film made of a transparent organic resin on the scanning signal line, the data signal line, and the switching element. Forming; and forming a pixel electrode on the interlayer insulating film excluding a region corresponding to an upper portion of the switching element;
The interlayer insulating film is opaquely dyed using the pixel electrode as a mask, and a region of the interlayer insulating film corresponding to an upper portion of the switching element, a region between the pixel electrodes, and a lower portion of a peripheral portion of the pixel electrode. Forming an insulating light-shielding film.

In a preferred embodiment, the pixel electrode is formed by patterning using a negative photoresist.

Hereinafter, the operation of the present invention will be described.

According to the present invention, the light-shielding film is formed from a dyeable and insulating material (particularly, an organic material). Such materials have lower reflectivity than metals,
There is no reduction in contrast due to reflection from the light shielding film. Further, since there is no need to overlap the signal wiring and the pixel electrode, no coupling capacitance is generated, and crosstalk is prevented.

In addition, since the pixel electrode and the light-shielding film are formed in a self-aligned manner and the pixel electrode and the light-shielding film are overlapped at the peripheral portion of the pixel electrode, the signal wiring does not overlap with the pixel electrode. However, it is possible to prevent a decrease in contrast due to light leakage due to disturbance of alignment of liquid crystal due to a lateral electric field of the pixel electrode. Furthermore, even if the source wiring is formed from a transparent conductive film such as ITO in order to simplify the manufacturing process,
Can be shaded.

In a preferred embodiment of the present invention, the patterning of the pixel electrode is performed using a negative resist. In the case of patterning so as to separate the pixel electrodes, the pixel electrode film remains between the pixel electrodes when the positive resist is used, but does not remain between the pixel electrodes when the negative resist is used. Therefore, it is possible to prevent leakage between the pixel electrodes due to the remaining pixel electrode film. In addition, since a light-shielding film is automatically formed between the pixel electrodes, it does not become a bright spot. Conversely, if peeling of the pixel electrode causes display failure, it is preferable to use a positive resist.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be specifically described below with reference to the drawings, but the present invention is not limited to these embodiments.

FIG. 1 is a schematic sectional view of a liquid crystal display according to a preferred embodiment of the present invention; FIG. 2 is a schematic plan view of an active matrix substrate of the liquid crystal display of FIG. 1; Of the active matrix substrate of FIG.
It is sectional drawing by the III-III line.

As shown in FIGS. 1 to 3, the liquid crystal display device 100 includes an active matrix substrate 9, a counter substrate 12, the active matrix substrate 9, and the counter substrate 1.
And a liquid crystal layer 13 disposed between the first and second liquid crystal layers.

In the active matrix substrate 9,
Switching elements (for example, TFTs) 2 arranged in a matrix on an insulating substrate 1 and gate wiring (scanning signal lines) for sending a gate signal to each switching element 2
3 and a source wiring (data signal line) 4 for transmitting a source signal (data signal). The gate wiring 3 and the source wiring 4 are provided in parallel with each other. The gate wiring 3 and the source wiring 4 are provided so as to cross each other (substantially orthogonal in this embodiment). An interlayer insulating film 5 is provided on the entire substrate so as to cover the switching element 2, the gate wiring 3, and the source wiring 4. Further, a pixel electrode 8 is provided on the interlayer insulating film 5.

The TFT 2 includes a gate electrode 14, a gate insulating film 15, a source electrode 16, a drain electrode 17, a semiconductor layer 18, a source connection wiring 19, and a drain connection wiring 2.
Has zero. Part of the gate wiring 3 forms a gate electrode 14, and part of the source wiring 4 forms a source electrode 16. The TFT 2 is electrically connected to the pixel electrode 8 via a contact hole 6 provided through the interlayer insulating film 5.

The counter substrate 12 has a color filter 10 having color layers R, G, and B on the insulating substrate 1; and a counter electrode 11.

As shown in FIGS. 1 to 3, in the present invention, the light-shielding film 7 is formed of the interlayer insulating film 5, the region corresponding to the upper part of the TFT 2, the region between the pixel electrodes 8, and
Is provided in a lower region of the peripheral portion of.

Hereinafter, a preferred example of a method for manufacturing such a liquid crystal display device will be described.

First, a gate wiring 3 and a gate electrode 14 are formed on an insulating substrate (eg, a glass substrate) 1 by depositing Ta, A1, or the like by a sputtering method and patterning the same. Next, the gate insulating film 1
5 is formed. Gate insulating film 15 is formed by anodizing gate wiring 3 and gate electrode 14 or by a plasma CVD method. When the gate insulating film is formed by anodic oxidation, the gate insulating film is made of, for example, tantalum oxide or aluminum oxide obtained by oxidizing a gate wiring and a gate electrode. When formed by a plasma CVD method, silicon nitride, silicon oxide, or the like is used alone or in combination.

Next, a semiconductor layer 18 is formed on the gate insulating film 15 by depositing and patterning non-doped amorphous silicon by, for example, a low-pressure CVD method or a plasma CVD method. Furthermore, by a plasma doping method or a low-acceleration ion implantation method,
A source electrode 16 and a drain electrode 17 are formed. Next, a source connection line 19 for electrically connecting the source electrode 16 and the source line 4 and a drain connection line 20 for electrically connecting the drain electrode 17 and the pixel electrode 8 are formed. Preferably, the source connection wiring 19 and the drain connection wiring 20 are made of a transparent conductive material (for example, IT
O). Further, A1, Ta, Cr,
The source wiring 4 is formed using Mo or ITO.

Further, an interlayer insulating film 5 is formed by using, for example, a spin coating method using a colorless and transparent material (particularly, an organic material) having dyeability and insulating properties. Examples of colorless and transparent materials having dyeability and insulating properties include, for example, gelatin, casein, glue, polyvinyl alcohol, polyvinylpyrrolidone, acrylic resin, polyimide, polyamide, polyurea, polyurethane, polycinnamic acid and derivatives thereof. Can be Preferred materials are acrylic resin and gelatin, and more preferred material is acrylic resin. If necessary, a photosensitive agent (for example, a dichromate, a diazo compound) can be added. The thickness of the interlayer insulating film can vary depending on the application of the obtained liquid crystal display device, the material used, and the like, but is preferably 1 to 4 μm.

After forming a contact hole 6 in the interlayer insulating film 5 by any appropriate method, a transparent conductive material (for example, ITO) is sputtered on the interlayer insulating film 5 and patterned to form a pixel. An electrode 8 is formed. The pixel electrode 8 is formed except for a region corresponding to an upper part of the TFT 2. Preferably, the patterning of the pixel electrode is performed using a negative resist.

Next, using the pixel electrode 8 as a mask, a predetermined portion of the interlayer insulating film 5 is opaquely dyed to form a light shielding film 7. The color to be dyed is not particularly limited as long as it has a light-shielding property, but is preferably black. Dyeing is performed, for example, by immersing the substrate on which the pixel electrode is formed in an acidic dye or a reactive dye, and then washing and removing the dye on the pixel electrode. As the acid dye, any appropriate acid dye (for example, Black-181 (manufactured by Nippon Kayaku Co., Ltd.)) is used. As the reactive dye, any suitable reactive dye is used. The immersion time can vary depending on the type of the dyeable material, the desired light shielding property of the light shielding film, and the like. In order to obtain sufficient light-shielding properties, it is preferable to dye the interlayer insulating film by 1 to 2 μm in the depth direction. When dyeing is performed in the depth direction of 1 to 2 μm, the dyeing is performed not only in the depth direction of the interlayer insulating film but also in the horizontal direction. You. Therefore,
An insulating light-shielding film 7 is formed in a region of the interlayer insulating film 5 corresponding to the upper part of the TFT 2, a region between the pixel electrodes 8, and a region below the periphery of the pixel electrode 8. Finally, an orientation film is formed by any appropriate method, and the active matrix substrate 9 is obtained.

On the other hand, an insulating substrate (for example, a glass substrate)
A color filter 10, a counter electrode 11 made of ITO or the like, and an alignment film are formed on 1 to obtain a counter substrate 12.

The active matrix substrate 9 and the opposing substrate 12 manufactured as described above are bonded together with a sealing material therebetween, and a liquid crystal material is sealed between the bonded substrates to form a liquid crystal layer 13. Get 100.

The width of the light-shielding film 7 formed between the pixel electrodes 8 is, as shown in FIGS.
And may be narrower than the width of the gate wiring 3, or may be wider than the width of the source wiring 4 and the gate wiring 3 as shown in FIG.

The source electrode and the source wiring and their connection wiring, or the drain electrode and the drain wiring and their connection wiring are made of a transparent conductive material (for example, IT
By simultaneously forming O), the manufacturing process can be further simplified.

[0036]

According to the present invention, there is provided a liquid crystal display device which is excellent in display quality, has a high aperture ratio, and is excellent in yield, and a simple and inexpensive method for manufacturing such a liquid crystal display device.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a liquid crystal display according to a preferred embodiment of the present invention.

FIG. 2 is a schematic plan view of an active matrix substrate of the liquid crystal display device of FIG.

3 is a cross-sectional view of the active matrix substrate of FIG. 2, taken along the line III-III.

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

FIG. 5 is a schematic sectional view of a conventional liquid crystal display device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulating substrate 2 Thin film transistor 3 Gate wiring 4 Source wiring 5 Interlayer insulating film 6 Contact hole 7 Light shielding film 8 Pixel electrode 9 Active matrix substrate 10 Color filter 11 Counter electrode 12 Counter substrate 13 Liquid crystal layer 14 Gate electrode 15 Gate insulating film 16 Source Electrode 17 Drain electrode 18 Semiconductor layer 19 Source connection wiring 20 Drain connection wiring

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01L 29/786 H01L 29/78 619B

Claims (4)

[Claims] An active matrix substrate having a plurality of scanning signal lines and data signal lines provided crossing each other, switching elements provided in a matrix, and pixel electrodes; and a color filter and a counter electrode. A counter substrate having: a liquid crystal layer disposed between the active matrix substrate and the counter substrate; and an interlayer insulating film made of a transparent organic resin provided on the signal lines and the switching elements; A pixel electrode is provided on the interlayer insulating film except for a region corresponding to the upper part of the switching element; and a region of the interlayer insulating film corresponding to the upper part of the switching element, between the pixel electrodes And a liquid crystal display device provided with an insulating light-shielding film in a region below the peripheral portion of the pixel electrode. 2. The liquid crystal display device according to claim 1, wherein said data signal line is formed of a transparent material. Forming a scanning signal line, a data signal line, and a switching element on the substrate; and forming an interlayer insulating film made of a transparent organic resin on the scanning signal line, the data signal line, and the switching element. Forming a pixel electrode on the interlayer insulating film excluding a region corresponding to an upper portion of the switching element; dyeing the interlayer insulating film opaquely using the pixel electrode as a mask to form the interlayer insulating film; Forming an insulating light-shielding film in a region of the film corresponding to an upper portion of the switching element, a region between the pixel electrodes, and a region below a peripheral portion of the pixel electrode. Method. 4. The method according to claim 3, wherein the pixel electrode is formed by patterning using a negative photoresist.