JPH0973078A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent liquid crystal driving voltage from getting higher as far as possible and to realize high-definition picture display. SOLUTION: This device is provided with a switching element 7 formed on a 1st transparent substrate 2, a color filter 9 formed on the 1st transparent substrate so as to cover the switching element 7, an array substrate having a picture element electrode 14 formed on the color filter 9, a counter substrate having a counter electrode formed on a 2nd transparent substrate so as to be opposed to the electrode 14, and a liquid crystal layer sealed in a gap between the array substrate and the counter substrate; and the switching element 7 and the electrode 14 are electrically connected by a metallic film 11 deposited by using an optical CVD method in a through-hole 10 formed on the color filter 9.

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 Generally, in order to realize a color image display in a liquid crystal display device, a color filter having a plurality of colored portions arranged so as to correspond to a plurality of pixels of a liquid crystal display element is used. For example, R (red), G (green), B
A color filter formed so that colored cells colored in each hue of (blue) are arranged alternately is used.

A conventional color filter is a thin film transistor (thin film transistor) in which a switching element is formed.
nsistor: Substrate (hereinafter referred to as TFT) (hereinafter,
It was formed not on the TFT substrate side, but on the counter substrate side facing this substrate. That is, a color filter is arranged on a transparent substrate different from the TFT substrate, and the amount of light passing through the color filter is changed by a switching element including a TFT, thereby realizing a color display image.

However, particularly in the active matrix type liquid crystal display device, when the color filter is arranged on the counter substrate side, it is not easy to align the pixel filter with each pixel electrode on the TFT substrate, and the color filter and the liquid crystal layer are arranged. Since the distance is relatively large, there is a problem that the light incident from the oblique direction becomes stray light and the display quality is degraded. And
As the screen becomes more and more pixels, the miniaturization progresses, and thus the above-mentioned problems of alignment of color filters and deterioration of display quality become more serious.

Therefore, a technique has already been known in which a color filter is arranged immediately above or below the pixel electrode. Particularly in an active matrix type liquid crystal display device such as a TFT, each switching element connected to pixel electrodes corresponding to the same hue is turned on and a voltage is applied,
Alternatively, a technique has been developed in which an electrodeposited electrode corresponding to the same hue is provided and a colored layer is electrodeposited directly on the electrodeposited electrode to form a color filter. (JP-A-60-238
34).

According to this technique, since the color filter can be arranged directly above the pixel electrode or the electrodeposited electrode in a self-aligned manner, the color filter can be arranged on the TFT substrate as in the case where the color filter is arranged on the counter substrate side. The problem of alignment with each pixel electrode and the problem of deterioration of display quality due to stray light are solved.

However, when the color filter is provided on the pixel electrode connected to the switching element, the voltage applied to the liquid crystal is divided by the capacitance of the color filter, which causes a problem that a high voltage is required to disturb the liquid crystal. To do.

Further, when the pixel electrode is arranged on the color filter, how to make an electrical connection with the TFT element becomes a problem. That is, in the case of a structure in which a wiring made of ITO or the like is provided at the end of each pixel of the color filter and the TFT element and the pixel electrode are connected to each other, in order to manufacture with high reliability and high non-defective rate, the connecting part is considerably A margin is required, which causes a problem of lowering the aperture ratio. On the other hand, TF
Through hole (connection hole) in the color filter near the T element
In the case of a structure in which the TFT element and the pixel electrode are connected with each other, the through hole is highly reliable and high especially by wet etching (wet etching using an etching solution) or patterning of a photosensitive material, that is, a wet method (wet process). To manufacture with a good product rate, for example, 1-2 μ
The diameter of the through-hole provided in the color filter having a thickness of about m has a considerable margin, specifically 10 to 30.
A margin of about μm is required, which causes a problem that the aperture ratio is reduced.

The present invention has been made in consideration of the above circumstances, and provides a liquid crystal display device capable of preventing an increase in liquid crystal driving voltage as much as possible and realizing high quality image display. The purpose is to provide.

[0010]

According to a first aspect of a liquid crystal display device of the present invention, a switching element is formed on a first transparent substrate, and the switching element is formed on the first transparent substrate so as to cover the switching element. An array substrate having a color filter, a pixel electrode formed on the color filter, a counter substrate having a counter electrode formed on a second transparent substrate so as to face the pixel electrode, and the array substrate. A liquid crystal layer sealed in a gap between the counter substrate and
The switching element and the pixel electrode are formed in the through hole formed in the color filter by photo CVD.
It is characterized by being electrically connected by a metal film deposited by using the method.

A second aspect of the liquid crystal display device according to the present invention is a switching element formed on a first transparent substrate,
An array substrate having a color filter formed on the first transparent substrate so as to cover the switching element, and a pixel electrode formed on the color filter, and a second transparent substrate so as to face the pixel electrode. A counter substrate having a counter electrode formed on a substrate, the array substrate, and a liquid crystal layer sealed in a gap between the counter substrate and the plurality of switching elements and the pixel electrodes formed on the color filter. Is electrically connected by a metal film formed at the same time as the pixel electrode so as to cover the through hole.

A third aspect of the liquid crystal display device according to the present invention is the liquid crystal display device according to the first or second aspect,
The through holes are formed by using an excimer laser.

A fourth aspect of the liquid crystal display device according to the present invention is the liquid crystal display device according to the first or second aspect,
The through hole is formed by a dry etching method.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment of a liquid crystal display device according to the present invention.
The embodiment will be described with reference to FIGS.

FIG. 3 is a plan view of the liquid crystal display device according to the first embodiment, and FIG. 1 is a sectional view of a TFT substrate (also referred to as an array substrate) of the liquid crystal display device according to the first embodiment. . This sectional view is a sectional view taken along the line X1-X1 shown in FIG. The cutting line X2 shown in FIG.
A cross-sectional view taken along the line X2-is shown in FIG.

The liquid crystal display device of the first embodiment comprises an array substrate 1, a counter substrate 20, and a liquid crystal layer 30 sealed in a gap between these substrates (see FIG. 2). The array substrate 1 is manufactured as follows.

First, a metal film made of chromium is formed on the glass substrate 2 using a known technique, and then patterned to form the scanning lines 3 and the gates 3a (see FIG. 1). Then, a transparent insulating film 4 made of, for example, silicon nitride is formed on the entire surface of the glass substrate 2 so as to cover the scanning lines 3 and the gates 3a. Next, a semiconductor layer 5 made of amorphous silicon is formed using a known technique, and then an aluminum layer is deposited on the entire surface and patterned to form a source electrode 6a, a drain electrode 6b, and a signal line 8. The gate 3a, the insulating film 4,
The semiconductor layer 5 and the source / drain electrodes 6a and 6b constitute a TFT element 7 which serves as a switching element.

Then, using a known technique, a color filter 9 is formed by arranging three colored cells of red (R), green (G) and blue (B) (see FIG. 1). The color filter 9 includes the scanning line 3, the TFT element 7, and the signal line 8.
Are formed so as to cover without gaps.

Next, a through hole 10 for making contact with the TFT element 7 is formed by a photolithography technique. To form the through hole 10, first, a photoresist is applied to the entire surface of the substrate on which the color filter 9 is formed by using a spin coater. Then, a photoresist mask (not shown) is formed by patterning this photoresist, and dry etching (for example, RIE (Reactive Ion Etching) or photoexcitation etching) is used to form a through hole having a diameter of 3 μm in the color filter 9. The hole 10 is formed.

Next, after removing the photoresist mask, a metal film 11 is deposited in the through hole 10 by using a photo-CVD (Chemical Vapoun Deposition) method. Specifically, a raw material gas (for example, a methylated metal such as Al, Cd, Sn, and Zn, a carbonyl metal, or the like) is flown over the through hole 10 of the color filter 8 and is irradiated with ultraviolet light to photolyze the raw material gas. Then, the photodecomposition product (metal) is deposited in the through hole 10 to form a thin film. Since this photo CVD method can be performed at a relatively low temperature of 50 to 200 ° C., it does not adversely affect the color filter 8. Although ultraviolet light is used as the irradiation light in the above photo-CVD method, it is also possible to use laser light (for example, excimer laser).

In this case, if the laser beam is also used for forming the through hole 10, the through hole 10 and the metal film 11 can be continuously formed by using the laser beam. Further, when a laser is used, the beam can be narrowed down to a size of about the wavelength, so that a metal film can be formed in the through hole 10 having a diameter of about 1 μm. In addition, when the beam or the substrate is moved, fine drawing can be performed without a mask. Therefore, a mask for a photoresist is not needed and the process can be simplified.

As described above, the metal film 1 is formed in the through hole 10.
After forming No. 1, a film made of ITO (Indium Tin Oxide) is formed on the entire surface by sputtering and then patterned by using a photolithography technique to form the pixel electrode 14. The pixel electrode 14 is the metal film 1 in the through hole 10.
It is electrically connected to the TFT element 7 via 1. After that, the alignment film 1 is formed on the entire surface of the substrate 2 on the TFT element formation side.
5 is formed, and the polarizing plate 16 is formed on the surface opposite to the surface on which the alignment film 5 is formed, whereby the array substrate 1 is completed.

On the other hand, the counter substrate 20 is formed as follows. First, the counter electrode 24 is formed by forming an ITO film on the glass substrate 22 so as to face the pixel electrodes 14 of the array substrate 1 by a sputtering method. Then, polyimide is applied so as to cover the entire surface of the counter electrode, and then an alignment treatment is performed to form an alignment film 26.

After the array substrate 1 and the counter substrate 20 are bonded together, a polarizing plate 16 is attached to the surface of the array substrate 1 opposite to the surface on which the alignment film 5 is formed, and the counter electrode 24 of the counter substrate 20 is formed. The polarizing plate 28 is attached to the surface opposite to the arranged surface, that is, the surface on the display side of the glass substrate 22. A light source as a backlight is provided outside the surface of the array substrate 1 on which the polarizing plate 16 is attached. Further, the liquid crystal 3 sealed in the space between the array substrate 1 and the counter substrate 20.
As 0, a general TN (twisted nematic type) is used.

As described above, according to the liquid crystal display device of this embodiment, the through hole 10 for connecting the pixel electrode 14 and the TFT element 7 is formed in the color filter 9 by dry etching or laser. . As a result, the margin for forming the through hole can be small, and it is possible to manufacture with a high yield rate without lowering the aperture ratio.

Further, according to the liquid crystal display device of the present embodiment, since the pixel electrode 14 is formed on the color filter 9, it is possible to prevent the liquid crystal drive voltage from increasing as much as possible. Moreover, since the metal film 11 in the through hole 10 is formed by the photo-CVD method, it can be formed at a low temperature and does not adversely affect the color filter. Therefore, high-quality image display can be provided.

Next, FIG. 4 shows a structural cross-sectional view of a second embodiment of the liquid crystal display device according to the present invention. The liquid crystal display device according to the second embodiment is different from the liquid crystal display device according to the first embodiment shown in FIG. 1 in that a plurality of through holes 10 provided in the color filter 9 are provided at one connection portion (see FIG. The metal film 13 deposited on the through hole 10 is made of ITO and is formed by the sputtering method at the same time when the pixel electrode 14 is formed.

The through holes 12 are formed by dry etching or laser as in the case of the first embodiment. When an excimer laser is used to form the through holes 12, the excimer laser decomposes only organic substances, so that only the color filter 9 is processed and the TFT
The element 7 is not damaged.

In the liquid crystal display device of the second embodiment, a plurality of (two in FIG. 4) through-holes 12 are provided for the connection portion of the TFT element 7 and the pixel electrode 9 at one location.
Since it is connected with, even a small size through hole is 1
Since it suffices that the individual through holes be connected, defective connections can be reduced, and high yield can be achieved. Also,
Since it is a small-sized through hole, it is possible to increase the aperture ratio and it is possible to cope with high definition.

Needless to say, the liquid crystal display device of this embodiment also has the same effects as the liquid crystal display device of the first embodiment.

Further, in the liquid crystal display device of the present embodiment, the larger the number of through-holes 12 is, the better as long as it is within the range allowed by the space in consideration of the aperture ratio, and the connection failure is further reduced. .

[0032]

As described above, according to the liquid crystal display device of the present invention, it is possible to prevent the liquid crystal drive voltage from increasing and it is possible to realize high-quality image display.

[Brief description of drawings]

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

FIG. 2 is a sectional view showing a configuration of a first embodiment of a liquid crystal display device according to the present invention.

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

FIG. 4 is a sectional view showing a configuration of an array substrate according to a second embodiment of a liquid crystal display device according to the present invention.

[Explanation of symbols]

 1 array substrate 2 glass substrate 3 scanning line 3a gate electrode 4 transparent insulating film 5 semiconductor layer 6a source electrode 6b drain electrode 7 TFT element 8 signal line 9 color filter 10 through hole 11 metal film 12 through hole 13 metal film 14 pixel electrode 15 Alignment Film 16 Polarizing Plate 20 Counter Substrate 22 Glass Substrate 24 Counter Electrode 26 Alignment Film 28 Polarizing Plate 30 Liquid Crystal

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Teruyuki Midorikawa 1-7 Nisshin-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa Toshiba Electronics Engineering Co., Ltd.

Claims (4)

[Claims] 1. A switching element formed on a first transparent substrate, a color filter formed on the first transparent substrate so as to cover the switching element, and a pixel electrode formed on the color filter. An array substrate, an opposed substrate having an opposed electrode formed on a second transparent substrate so as to face the pixel electrode, and a liquid crystal layer sealed in a gap between the array substrate and the opposed substrate. The switching element and the pixel electrode are formed by photo CVD in a through hole formed in the color filter.
A liquid crystal display device characterized by being electrically connected by a metal film deposited by using a method. 2. A switching element formed on a first transparent substrate, a color filter formed on the first transparent substrate so as to cover the switching element, and a pixel electrode formed on the color filter. An array substrate, an opposed substrate having an opposed electrode formed on a second transparent substrate so as to face the pixel electrode, and a liquid crystal layer sealed in a gap between the array substrate and the opposed substrate. The liquid crystal display device is characterized in that the switching element and the pixel electrode are electrically connected by a metal film formed at the same time as the pixel electrode so as to cover a plurality of through holes formed in the color filter. 3. The liquid crystal display device according to claim 1, wherein the through hole is formed by using an excimer laser. 4. The liquid crystal display device according to claim 1, wherein the through hole is formed by a dry etching method.