JPS5949566B2 - liquid crystal display element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dielectric film coated on an electrode substrate of a liquid crystal display element.

Conventionally, in a TN-FEM liquid crystal display element, liquid crystal molecules are aligned horizontally with respect to a cell substrate, and there is a well-known rubbing method as a method for this purpose.

Furthermore, the liquid crystal molecules have a twisted structure between the upper and lower substrates (see FIG. 1). In this case, in order to horizontally align the liquid crystal molecules, a dielectric film having good wettability with the liquid crystal is coated on the electrode and used as a liquid crystal horizontal alignment layer. Conventionally, this dielectric film is Si02, TiO2, MgF2, Y203.
, organic polymer dielectric films containing imide rings, etc. When forming these dielectric films, a mask was required at the lead-out portion of the electrode (see FIG. 2), and selection of the mask material became a problem. The following mask materials were used here. That is, the dielectric film is SiO
2. MetalMask is generally used when TiO2, Y2O3, etc. are formed by vacuum evaporation, and printing of the Mask material is used for organic polymer dielectric films where the dielectric film is applied using a spinner, spray, etc. used.
In the case of the MetalMask mentioned above, the setting must be done manually, which takes time, and
When printing sk materials, the material must be insoluble in the dielectric film coating solution, and after coating and drying.
It is often extremely difficult to select the material because it is easy to remove with a solvent, which is one of the causes of instability in the process.

The present invention solves the above-mentioned conventional drawbacks, and aims to provide a novel method for forming a dielectric film, which is completely different from conventional methods for forming a dielectric film.

Hereinafter, one embodiment of the present invention will be described in detail using the drawings.

The present invention makes it possible to achieve IN-LINE automation of alignment film formation using PhotoProcessLine by using a photolytic alkali-soluble polymer dielectric film.

The material for the dielectric film is an O (ortho)-naphthoquinonediazide dielectric. This is generally Posi-type
It is commercially available as eResist and is manufactured by Shipley.
AZ-119, -1350J, -34O from GAF, GAF MicroLine PR-102, 115 from GAF, OFPR from Tokyo Ohka, etc. The naphthoquinonediazide dielectric material is made of naphthoquinonediazide sulfonic acid chloride and an alkali-soluble polymer (phenol/novolac resin, PVAI cellulose, etc.)
alkali-soluble polymers containing esters or monomers containing hydroxyl groups [OH], such as hydroquinone,
A variety of resorcinols can be obtained by combining esters such as chloroglucine and hydroxybenzophenone with the above polymers, and one example will be described next. In general, a liquid crystal molecule has one or more benzene rings in a linear chain as shown in the following structural formula, and the molecule as a whole has an elongated structure.

R, R': Alkyl group, and the photodecomposed alkali-soluble resin according to the present invention is naphthoquinone-1(1,2)-diazide-(2 )-5-sulfonic acid novolac ester.

{However, m≧N. m and n are integers} This photolytic alkaline resin also has a large number of benzene rings and also has polar groups such as -SO2-, -0-, and =O, so it horizontally aligns the liquid crystal molecules by light splitting. In addition, due to the presence of one --SO2 group, the polymer membrane itself has flexibility, and a groove format using rubbing can also be effectively achieved.

Spin the above photodecomposed alkaline resin on a transparent electrode.
The r-coat is dried, masked with a predetermined photomask (see FIG. 3), and then exposed.

The exposed areas become alkali-soluble and are then developed with an alkaline solution.

During development, an organic alkaline aqueous solution (Shipley: M
A metal-free developer consisting of F-312, Tokyo Ohkasha NMD, etc.) is used. After the development process, a polymer having the structure of the above formula (2) remains in the afterimage area, but since this part has an azide group (=N2) that has photosensitivity, 200 and CX2
Heat treatment (POst-Bake) for about 0 minutes thermally decomposes the azide group to eliminate photosensitivity, and at the same time increases the adhesion of the resist material to the substrate, or re-exposes this afterimage area to convert it into carboxylic acid. Furthermore, the above heat treatment (POst-B
ake) may be used for thermal decomposition. Also, especially when the adhesion between the substrate and the resist material is a problem, for example, 0rgan0c.
h10rnsi1ane, disi1yamide, h
The resist may be applied after the surface of the substrate is treated with experimenty1disi1azane or the like. After the above treatment, known rubbing is performed to form cells. Next, two examples of specific formation of a liquid crystal display element according to the present invention obtained through experiments will be explained. First example: Place OFPR (manufactured by Tokyo Ohka Co., Ltd.) on a transparent electrode substrate using a spinner. A film with a thickness of 2500λ was obtained by heating at 80°C1.
After performing Pre-Bake for 0 minutes, exposure was performed using a predetermined photomask, and then development was performed using an NMD developer (manufactured by Tokyo Ohka Co., Ltd.).

After that, it was washed with pure water and post-treated at 200℃ for 30 minutes.
I went to Bake. At this time, it was confirmed by an infrared absorption spectrum that the infrared absorption intensity of the azide group (=N2) had disappeared (~2000CT! l-ri. After that, Rub
Bing was performed to form cells. As the injected liquid crystal, biphenyl+ester liquid crystal was used. As a result, a high-contrast liquid crystal cell with very good alignment was obtained. Second Example After the development process in the first example, re-exposure was carried out.

Thereafter, Post-Bake was performed at 200°C for 20 minutes. Thereafter, cells were formed in the same manner as in the first example. As a result, a high-contrast liquid crystal cell with very good alignment was obtained. According to the present invention as described above, the liquid crystal alignment film is formed of a photolytic alkali-soluble polymer film, and naphthoquinonediazide nerfonic acid ester is used as the material of the photolytic alkali-soluble polymer dielectric film. , at least a plurality of continuously connected benzene rings in the substance, and -S02
Because of this, it has good wettability for liquid crystal molecules and can perform a good horizontal alignment effect, and has sufficient flexibility, so it can effectively form grooves by rubbing. .

That is, a good liquid crystal alignment film can be realized. Furthermore, since the lead-out portions of the electrodes and the like can be removed by exposure, it is possible to achieve IN-LINE automation using a photo process line.

[Brief explanation of drawings]

FIG. 1 is an explanatory external perspective view of a liquid crystal cell, FIG. 2 is a plan view of the liquid crystal cell, and FIG. 3 is a plan view of the liquid crystal cell after photomasking. In the figure, 1: substrate, 2: liquid crystal molecules, 3: electrode extension part,
4: Photomask.

Claims (1)

[Claims] 1. A liquid crystal display element characterized in that an electrode substrate is coated with a photolytic alkali-soluble polymer dielectric film made of naphthoquinonediazide sulfonic acid ester, and the dielectric film is used as an alignment film for liquid crystal molecules.