JP2003140157A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device which is provided with post spacers, however, in which uneven film thickness or rubbing unevenness of an alignment layer is hardly observable and which exhibits high picture quality. SOLUTION: In the liquid crystal display device with a structure wherein a liquid crystal substance is sandwiched between a pair of substrates, placed opposite to each other, of which the interval is adjusted as specified by a plurality of the mutually independent post spacers, the post spacers are aligned in a checkered pattern with a ratio of one post spacer for every two pixels and equivalently distributed per pixel on one substrate out of a pair of the substrates.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device provided with a high-quality image in which unevenness in the film thickness and rubbing unevenness of an alignment film are hard to be visually recognized even though it has a columnar spacer.

[0002]

2. Description of the Related Art Generally, a liquid crystal display device has a structure in which a liquid crystal substance is sandwiched between a pair of substrates facing each other. Here, the image display by the liquid crystal display device is performed by applying a voltage between the pair of substrates and controlling the light transmittance based on the birefringence characteristic of the liquid crystal substance. Therefore, when the distance between the opposing substrates is not uniform in the screen, the electric field strength applied between the opposing electrodes is different in the screen, which is a serious problem in image quality. Therefore, conventionally, a predetermined amount of fine glass beads are dispersed on one of the substrates as a spacing member, and as a result, the glass beads are dispersed in the liquid crystal substance, thereby providing a predetermined spacing between the pair of substrates. I was adjusting.

However, it is very difficult to uniformly disperse the glass beads on one of the substrates, and in some cases, the glass beads are unevenly distributed (localized) in the screen, which causes a problem of deterioration of image quality. It was

Therefore, in recent years, rather than spraying glass beads on a substrate, it is possible to realize relatively good positional accuracy, dimensional accuracy, and shape accuracy on one of a pair of substrates facing each other. It is possible to provide a spacing member (that is, columnar spacers that are independent of each other) in which an insulating resin such as a photosensitive resin or an insulator such as an oxide film such as SiO ₂ is formed in an island shape by using a lithography technique or an etching technique. Has been done.

[0005]

However, the formation of the alignment film such as polyimide (PI) and the rubbing treatment are performed after the formation of the columnar spacers. Therefore, if the columnar spacers are formed indiscriminately, they will be caused by the uneven shape of themselves. As a result, there is a problem that the film thickness unevenness and the rubbing unevenness that can be visually recognized at the time of forming the alignment film are generated, the liquid crystal alignment is abnormally caused, and the image quality obtained in the liquid crystal display device is extremely deteriorated.

The present invention is intended to solve the problems of the prior art, and a liquid crystal display that provides a high-quality image with the film thickness unevenness and the rubbing unevenness of the alignment film hardly visible, even though the spacers are provided. The purpose is to provide a device.

[0007]

The present inventors have found that the above-mentioned problems can be solved or alleviated by making the arrangement of the columnar spacers a specific pattern, and have completed the present invention.

That is, the present invention provides a liquid crystal display device having a structure in which a liquid crystal substance is sandwiched between a pair of opposed substrates which are adjusted to have a predetermined distance by a plurality of independent columnar spacers. Provided is a liquid crystal display device, wherein columnar spacers are arranged in a checkered pattern on one substrate at a rate of one for every two pixels and equivalent to each pixel.

Further, in this liquid crystal display device, in a method of manufacturing a liquid crystal display device having a structure in which a liquid crystal substance is sandwiched between a pair of substrates facing each other, two pixels are formed on one substrate of the pair of substrates. Provided is a manufacturing method including a step of forming columnar spacers in a checkered pattern so as to be equivalent to each pixel at one ratio.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The liquid crystal display device of the present invention has a structure in which a liquid crystal substance is sandwiched between a pair of substrates facing each other, which are adjusted to have a predetermined interval by a plurality of columnar spacers independent of each other. .

According to the knowledge of the present inventors, the alignment film applied on the columnar spacers is accumulated around the columnar spacers, and the film thickness unevenness of the alignment film is apt to occur. 2 (a) from the point that the image quality is deteriorated because the unevenness of the film thickness is visually recognized.
It is conceivable that one columnar spacer 23 is provided for each pixel between the pixel electrodes 22 arranged in a matrix on the substrate 21 and is equivalent to each pixel as shown in FIG. In the case of 2 (a), it was found that the arrangement density of the columnar spacers 23 was too high, the alignment of the liquid crystal substance was hindered, and alignment disorder called disclination was likely to occur.

On the other hand, as shown in FIG. 2B, when the columnar spacers 23 are arranged in a checkered pattern which is equivalent to each pixel at a rate of 4 pixels, the unevenness of the film thickness of the alignment film is made uniform. Although it was found that it is hard to be visually recognized, the effect can be expected when the aperture ratio is 54 in the case of a semi-transmissive liquid crystal display device in which the size of the pixel electrode 22 is 18 μm square.
It has been found that the limit is up to about 60%, which cannot be expected for a recent semi-transmissive liquid crystal display device having an aperture ratio of about 66% or more.

Therefore, in the present invention, as shown in FIG.
The columnar spacers 3 are arranged in a checkered pattern at a ratio of one to two pixels and equivalent to each pixel. This makes it possible to keep the gap between the substrates in the screen constant, prevent the columnar spacers 3 from approaching each other excessively, and even the unevenness of the film thickness of the alignment film to prevent the occurrence of disclination. It is possible to improve the quality of image quality.

Further, when considering an arbitrary columnar spacer 3 among a plurality of columnar spacers 3 formed in a checkered pattern as a center, there are four columnar spacers 3 adjacent to the periphery thereof. It is more preferable that the central columnar spacer 3 and the four columnar spacers 3 adjacent to the central columnar spacer 3 have substantially the same distance.

Further, in the present invention, a plurality of pixel electrodes 2
Are preferably formed in a matrix on one of the pair of substrates 1 as shown in FIG.

The smaller the columnar spacers 3 are, the more difficult it becomes to hinder the alignment of the liquid crystal. Therefore, the cross-sectional area thereof is preferably 1 to 100 μm ² , and preferably 5 to ² .
It is 5 μm ² .

As described above, the liquid crystal display device of the present invention is characterized by the arrangement of the columnar spacers, but other components, the pair of substrates, the liquid crystal substance, the electrodes, etc. are the same as those of the known liquid crystal display device. A similar configuration can be adopted.

The liquid crystal display device of the present invention, that is, the liquid crystal display device having a structure in which a liquid crystal material is sandwiched between a pair of substrates facing each other, has a ratio of one to two pixels and is equivalent to each pixel. It can be manufactured by a known manufacturing method except that the columnar spacers are formed in a checkerboard pattern. For example, a photosensitive resin may be applied onto one of a pair of substrates and dried to form a photosensitive resin layer, and the photosensitive resin layer may be processed into a columnar spacer by a photolithography method.

[0019]

EXAMPLE A manufacturing example of the liquid crystal display device (active matrix type liquid crystal display device) of the present invention shown in FIG. 3 will be described below.

First, a semiconductor thin film 32 (for example, polycrystalline silicon) forming a TFT is formed on a drive substrate 31 made of glass or the like with a thickness of 50 to 150 nm. If necessary, after implanting Si ⁺ ions to decrystallize, 600
Larger particles may be obtained by heat treatment at about ° C or by annealing with an excimer laser or the like.

This semiconductor thin film 32 is patterned into a predetermined shape, and a gate insulating film 33a is formed to a thickness of 10 to 100 nm by means of a thermal oxidation method or an LPCVD method.

Next, polycrystalline silicon or MoSi, WSi, Al, Ta, Mo / T to be the gate electrode 33 is formed.
A metal layer of a, Mo, W, Ti, Cr or the like is formed and patterned. When polycrystalline silicon is used as the gate electrode 33, P ⁺ ions or the like may be thermally diffused in order to reduce the resistance.

After that, using the gate electrode 33 as a mask, impurity ions are implanted by an ion implantation method or an ion doping method to form a source region S and a drain region D.

Subsequently, PSG, NSG, etc. are used for 400 to 80
The first interlayer insulating film 34 is formed by atmospheric pressure CVD with a thickness of 0 nm. Contact holes CONS and COND communicating with the source region S and the drain region D are opened in this.

Then, a conductive thin film of Al or the like is formed to a thickness of 300 to 700 nm by sputtering or the like. This is patterned into a predetermined shape and processed into a source electrode 36S and a drain electrode 36D. On top of these, for example PSG
And the like are formed into a second interlayer insulating film 35 by atmospheric pressure CVD with a thickness of 300 to 2000 nm. CM as required
The surface flattening treatment of the second interlayer insulating film 35 may be performed by using the P method or the like.

After that, the drain electrode 36D and the light shielding film 37 are formed.
A contact hole CON2 is formed in the second interlayer insulating film 35 for electrical connection with the metal film that also serves as the contact hole. On top of this, a metal thin film, such as Ti, Al, Mo, Cr, W, TiNx, or a silicide of these metals, which becomes the light-shielding film 37 that also serves as a black mask, is formed by a method such as sputtering.
A film having a thickness of about 500 nm is formed and patterned into a predetermined shape.

On the light-shielding film 37, for example, PSG or the like is formed by atmospheric pressure CVD to a thickness of 300 to 2000 nm to form a third interlayer insulating film 38. In order to improve the orientation of the liquid crystal, the surface of the third interlayer insulating film 38 may be planarized by using the CMP method or the like, if necessary. The second interlayer insulating film 35 and the third interlayer insulating film 38 may be planarized by using SOG, an organic film, or the like by a spin coating method.

After that, a contact hole CON3 for making electrical connection with the pixel electrode 39 is opened in the third interlayer insulating film 38. On top of this, a metal or metal oxide film to be the pixel electrode 39 (a transparent conductive film such as an ITO film in the case of a transmissive liquid crystal display device, or a light-reflecting property of Ag, Al or the like in the case of a reflective liquid crystal display device) Conductive film) 30 to 10 by sputtering method
A film having a thickness of about 00 nm is formed and patterned into a predetermined shape. After that, if necessary, you may anneal at about 200-400 degreeC.

On top of this, for example, a photosensitive resin paint, etc.
After applying about 6 μm, the columnar spacers 40 are formed in a checkered pattern by patterning in an island shape as shown in FIG. 1 by using a photolithography technique. This columnar spacer 4
In addition to the photosensitive resin, 0 may be formed by forming an inorganic film such as SiO ₂ by the CVD method or by forming a non-photosensitive resin coating material by the spin coating method or the printing method and then patterning. The cross-sectional area of the columnar spacer 40 is 1 to
100 μm ² .

After that, an alignment film (not shown) made of PI or the like is formed on the drive substrate 1 by a conventional method, and a rubbing treatment for aligning the liquid crystal is performed with a buff material such as cotton.
A liquid crystal cell is constructed by stacking and fixing it on a counter substrate 42 having a counter electrode 41 which has been similarly processed. Then, the liquid crystal 43 is injected into the liquid crystal cell, and heat treatment is performed if necessary.
The liquid crystal display device is completed.

In the liquid crystal display device thus obtained, the distance between the driving substrate 31 and the counter substrate 42 is
It is kept uniform by the height of the columnar spacers 40, the visibility of the film thickness unevenness and rubbing unevenness of the alignment film is low, and disclination is unlikely to occur. Therefore, a high quality image can be obtained.

[0032]

According to the liquid crystal display device of the present invention, by making the array pattern of the columnar spacers a specific pattern, there is no alignment disorder of the liquid crystal, and it is possible to make the unevenness of the film thickness and the rubbing unevenness of the alignment film less visible. , High-quality images can be obtained.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an array pattern of columnar spacers in the present invention.

FIG. 2 is an explanatory diagram of an array pattern of columnar spacers for comparison.

FIG. 3 is a schematic sectional view of a liquid crystal display device of the present invention.

[Explanation of symbols]

1,21 substrates, 2,22 pixel electrodes, 3,23 columnar spacers

Claims (6)

[Claims] 1. A liquid crystal display device having a structure in which a liquid crystal substance is sandwiched between a pair of opposed substrates which are adjusted to have a predetermined distance by a plurality of independent columnar spacers, and one of the pair of substrates is a substrate. 2 pillar spacers on top
A liquid crystal display device, characterized in that the pixels are arranged in a checkered pattern so that one pixel and one pixel are equivalent. 2. The liquid crystal display device according to claim 1, wherein the distances between the arbitrary columnar spacers and the four columnar spacers existing adjacent to the periphery thereof are substantially the same. 3. The cross-sectional area of the columnar spacer is 1 to 100 μm.
The liquid crystal display device according to claim 1, wherein the ^2. 4. The liquid crystal display device according to claim 1, wherein a plurality of pixel electrodes are formed in a matrix on one of the pair of substrates. 5. A method for manufacturing a liquid crystal display device having a structure in which a liquid crystal material is sandwiched between a pair of substrates facing each other, wherein one pixel of two substrates is provided on one substrate of the pair of substrates. A manufacturing method including a step of forming columnar spacers in a checkered pattern so as to be equivalent to pixels. 6. A photosensitive resin layer is formed by applying a photosensitive resin on one substrate of the pair of substrates and drying the substrate, and the photosensitive resin layer is processed into a columnar spacer by a photolithographic method. The manufacturing method described.