JPH04324426A - Substrate for liquid crystal element and production thereof - Google Patents

Abstract

PURPOSE:To obtain the substrate which does not generate dust and static electricity and has good reproducibility at a low cost by providing an oriented film consisting of a photosensitive resin having rugged shapes on the surface onto a substrate body. CONSTITUTION:The resin having the rugged shapes is formed on the substrate and this resin consists of the photosensitive resin. Such structure is obtd. by forming the film 3 made of the photosensitive resin on the surface of the substrate body 2 and exposing the film 3 made of the photosensitive resin at prescribed patterns, then developing the film. Electron rays are utlizable as well in addition to various kinds of electromagnetic waves, such as visible rays, UV rays, X-rays and gamma rays, for the exposing processing of the film 3 consisting of the photosensitive resin. Projecting lines and grooves are formed nearly parallel to the rugged shapes to be formed. In addition, various kinds of shapes, such as shapes to make the sections crossing these lines or grooves as sine, square or triangular wave shapes can be adopted. The rugged shapes are formed by the lithography techniques used for producing semiconductors in this forming method and, therefore, the substrate is formed inexpensively with good reproducibility.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate for a liquid crystal element and a method for manufacturing the same.

0002

[Prior Art] Conventionally, substrates for liquid crystal elements have an alignment film on the surface to give alignment to liquid crystal molecules, and this alignment film is mainly formed by rubbing the surface of polyimide resin with a cloth. It was formed using the oblique evaporation method.

0003

However, when the alignment film is formed by the above-mentioned rubbing method, there are problems in that dust is generated and the alignment film is charged with static electricity. Furthermore, the shape of the surface of the alignment film formed by the rubbing method has a problem of poor reproducibility. On the other hand, the oblique evaporation method has the problem of high cost and poor reproducibility.

The present invention has been made in view of the above-mentioned circumstances, and it is an object of the present invention to provide a substrate for a liquid crystal element and a method for manufacturing the same which can solve the above-mentioned problems.

[0005]

[Means for Solving the Problems] The substrate for a liquid crystal element of the present invention has an alignment film made of a photosensitive resin having an uneven shape on the surface of the substrate body. Furthermore, in a preferred embodiment, a photosensitive polyimide resin is used as the photosensitive resin.

[0006] Furthermore, in the method of manufacturing a substrate for a liquid crystal element of the present invention, a photosensitive resin is applied to the surface of the substrate body, and then the photosensitive resin film is exposed to light in a predetermined pattern and then developed to form a pattern on the surface. An alignment film having an uneven shape having an alignment function is formed.

Examples of photosensitive resins include polyimide resins having a Si-Si bond in the main chain represented by the following formula 1, cresol novolak resins mixed with naphthoquinonediazide, cyclized rubbers with aromatic bisazide added, Examples include a mixture of phenol resin with aromatic azide, t-butoxycarbonate-esterified polyvinylphenol with onium acid added, polymethyl methacrylate, polybutene-1 sulfone, and polyglycidyl methacrylate.

[0008]

[Chemical formula 1] R1, R2, R3, R4, R5, R6, R7, R8, R
9, R10, R11, R12 are H, F, CnH2n+
1, a saturated hydrocarbon, a methoxy group or an ethoxy group. m is 1 or 2. l is 1 or 2.

Among these, photosensitive polyimide resins having Si--Si bonds in their main chains are particularly suitable for fine processing and are suitable resins for realizing the present invention. Various methods such as a coating method, a spin coating method, a dip coating method, and a Langmuir-Blodgett (LB) method can be used to form a film made of this photosensitive resin on a substrate.

[0010] In addition to various electromagnetic waves such as visible light, ultraviolet rays, X-rays, and γ-rays, electron beams can be used for photosensitizing a film made of a photosensitive resin.

Various shapes can be adopted for the uneven shape to be formed, such as a shape in which the protrusions and grooves are formed substantially parallel to each other, and a cross section crossing them has a sine wave, rectangular wave, or triangular wave shape. Among these, an uneven shape in which the cross-sectional shape of the protrusions is asymmetrical has the advantage that the pretilt angle of the display liquid crystal can be increased. When the protrusions and grooves are formed substantially parallel, the pitch is preferably 5 μm or less, preferably 1 μm or less, in order to improve the alignment of display liquid crystal to a practical level. Further, the convex and convex shaped protrusions to be formed do not have to be formed in only one direction, but may be formed in directions that intersect with each other.

0012

According to the structure of claim 1, an alignment film is formed on the surface of which an uneven shape is formed with good reproducibility. Further, claim 2 operates as follows. When a film made of a photosensitive resin is exposed to light in a predetermined pattern and at a predetermined amount of light, and then this film is developed, a predetermined pattern is formed. At this time, by appropriately selecting the amount of irradiation light, it is possible to leave a film made of photosensitive resin on the bottom of the groove portion. According to the configurations of claims 3 and 4, an alignment film having a fine and highly reproducible uneven shape on its surface is formed.

[0013]

【Example】

(Embodiment 1) A liquid crystal element substrate of this embodiment and its manufacturing method will be described with reference to FIGS. 1 to 3. In this example, first, n of polyamic acid represented by the following two formulas is
- A methylpyrrolidone (NMP) solution is spin-coated on the substrate body 2 with the electrode 1 to a thickness of 0.2 μm, and then prebaked at 250° C. for 1 hour to imidize the photosensitive polyimide shown in formula 1 above. A film 3 consisting of the following was formed.

[0015]

[Case 2] In the formula, R1 to R12, m, and l are the same as in formula 1 above.

Next, using a mask in which lines and spaces with a width of 0.25 μm were alternately provided, a KrF excimer laser (wavelength 248 nm, pulse energy 0.18 mJ) was used.
, exposure energy: 85.1 mJ/cm 2 , pulse frequency: 200 Hz). Next, development was performed using a 1:1 mixed solution of dimethylacetamide and ethanol. As a result, the surface of the membrane 3 has protrusions 7 as shown in FIG.
An uneven shape in which the grooves 8 and 8 were formed in parallel was formed with good reproducibility. At this time, because the exposure energy was set to 50 to 85% of the amount of light required to completely remove the groove, a film made of photosensitive polyimide with a thickness of about 0.1 μm remained at the bottom of groove 8. .

Next, as shown in FIG. 2, the film 3 is etched by irradiating the film 3 with an ion beam 4 at an angle of 60 degrees with respect to the substrate body 2, and the uneven shape of the film 3 surface is blazed as shown in FIG. The alignment film 5 was completed with an uneven shape having an angle (angle between the substrate surface and the longer oblique side) of about 30 degrees. The cross-sectional shape of each convex portion 6 of this alignment film 5 is asymmetrical with respect to a perpendicular line drawn from the apex.

Using this substrate, a cell with a gap of 10 μm was prepared, and 99 parts by weight of cyano-based TN liquid crystal and a blue dye (
injecting a mixture consisting of 1 part by weight of LSB-278);
The order parameters were calculated by measuring the two-color ratio. As a result, the order parameter was 0.75, and it was confirmed that the alignment film 5 manufactured in this example had good alignment performance.

Here, the order parameter S is the alignment film 5
Substitute the absorbance A when the polarization axis is aligned parallel to the length direction of the ridges and the absorbance A' when the polarization axis is aligned perpendicular to the length direction of the ridges into the following formula 1. This is the calculated value.

[0020]

[Math 1]

The substrate for a liquid crystal element of this embodiment is made of a resin having unevenness made of photosensitive polyimide, and an alignment film having an uneven shape with good reproducibility can be formed on the surface. In addition, in the manufacturing method of the liquid crystal element substrate of this example,
A film 3 made of photosensitive polyimide having Si-Si bonds in the main chain was formed, exposed to light in a predetermined pattern, and then developed. In the exposed areas, the Si-Si bonds were broken and the molecular weight was lowered. It was removed during development, forming a positive pattern. According to such a substrate for a liquid crystal element and its manufacturing method, there are no factors that generate dust or static electricity, so a good alignment film can be formed. Further, in this formation method, the uneven shape can be formed using lithography technology used in manufacturing semiconductors, so the alignment film can be formed at low cost and with good reproducibility.

(Example 2) A polyimide precursor represented by Formula 4 was synthesized by mixing the polyimide acid represented by Formula 2 above and a compound represented by Formula 3 below.

[0023]

[Chemical formula 3]

[0024]

[C4] In the formula, R1 to R12, m, and l are the same as in formula 1 above.

Next, on the substrate body 2 on which the transparent electrode 1 was formed, 100 layers of the synthesized polyimide precursor were laminated by the LB method to obtain the state shown in FIG. 1. After this Example 1
The polyimide precursor was imidized under the same conditions as described above.

Thereafter, photosensitive treatment and development treatment were performed in the same manner as in Example 1, and then ion beam etching was performed to form an alignment film 5 substantially similar to that in Example 1. Next, using this substrate, a cell similar to that in Example 1 (cell gap 10 μm) was prepared.
m) was formed, and the same liquid crystal as in Example 1 was injected into it. When the order parameter of this liquid crystal element was measured, it was 0.
．． 76, confirming that the alignment film 5 produced in this example exhibited good alignment performance.

[0027] In this example as well, the same effects as in Example 1 could be obtained.

(Example 3) A film 6 made of photosensitive polyimide was formed in the same manner as in Example 2. This film 6 was then exposed to X-rays and developed to form an alignment film 5 similar to that in Example 1.

In this example as well, the same effects as in Example 1 were obtained. In addition, when holography is used as a method for forming unevenness, it is possible to easily form an uneven shape having a sin wave shape in cross section, and it can be used.

(Example 4) Similarly to Example 1, the substrate body 2 with the electrode 1 was coated with a positive photosensitive resin (A made by Shipley Co., Ltd.) made of a mixture of cresol novolac resin and naphthoquinone diazide.
Z1350J) was spin-coated to a thickness of 0.2 μm to form a film 3 made of a photosensitive resin.

Next, using a mask in which lines and spaces each having a width of 0.25 μm were alternately provided, exposure processing was performed using a high-pressure mercury lamp. Then, development was performed using a 2.38% aqueous solution of tetramethylammonium hydroxide. Further, ion beam etching was performed to form an alignment film 5 substantially similar to that in Example 1. When a cell similar to that in Example 1 was formed using this substrate, the same effects as in Example 1 were obtained.

(Example 5) Similarly to Example 1, a negative photosensitive resin (OMR83 manufactured by Tokyo Ohka Co., Ltd.), which is made by adding aromatic bisazide to cyclized rubber, was applied to the substrate body 2 with the electrode 1 to a thickness of 0.
A film 3 made of photosensitive resin was formed by spin coating to a thickness of 2 μm.

Next, using a mask in which lines and spaces each having a width of 0.25 μm were alternately provided, exposure processing was performed using a high-pressure mercury lamp. Next, development was performed using a commercially available xylene developer (OMR developer manufactured by Tokyo Ohka Co., Ltd.). Furthermore, ion beam etching was performed to form an alignment film 5 substantially similar to that in Example 1. When a cell similar to that in Example 1 was formed using this substrate, the same effects as in Example 1 were obtained.

(Example 6) Similarly to Example 1, negative photosensitive resin (OEBR manufactured by Tokyo Ohka Co., Ltd.) was used on the substrate body 2 with the electrode 1.
-100) to a thickness of 0.2 μm to form a film 3 made of a photosensitive resin.

Next, using a mask in which lines and spaces each having a width of 0.25 μm were provided alternately, an electron beam (2.0
Exposure processing was performed at ×10 −6 C/cm 2 and an acceleration voltage of 20 KV). Then, development was performed using a commercially available special developer. Further, ion beam etching was performed to form an alignment film 5 substantially similar to that in Example 1. When a cell similar to that in Example 1 was formed using this substrate, the same effects as in Example 1 were obtained.

Although limited examples have been described above, the photosensitive resin that can be used in the present invention includes various materials as described above, and the excitation source for irradiation includes visible light, ultraviolet rays, and X-rays. , gamma rays, electron beams, etc. are applicable.

[0037]

As explained above, the substrate for a liquid crystal element according to the present invention has an alignment film made of a photosensitive resin having an uneven surface on the substrate body. In addition, the method for manufacturing a substrate for a liquid crystal element of the present invention involves forming a film made of a photosensitive resin on the surface of the substrate body, and then exposing the film of the photosensitive resin to light in a predetermined pattern and developing it. This is a method of forming a substrate having an uneven shape having an alignment function.

According to such a substrate for a liquid crystal element and its manufacturing method, a predetermined pattern is formed on the surface of a film made of a photosensitive resin, so that a good substrate can be formed without causing dust or static electricity. can. Further, in this formation method, the uneven shape is formed using lithography technology used in manufacturing semiconductors, so the substrate can be formed at low cost and with good reproducibility.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing a state in which a photosensitive polyimide film is formed on the surface of a substrate.

FIG. 2 is a cross-sectional view showing a developed state of a photosensitive polyimide film.

FIG. 3 is a cross-sectional view showing a completed liquid crystal element substrate.

[Explanation of symbols]

2　Board body 3 Photosensitive polyimide film 5 Alignment film

Claims (4)

[Claims] 1. A substrate for a liquid crystal element, comprising an alignment film made of a photosensitive resin having an uneven surface on a substrate body. 2. A film made of a photosensitive resin is formed on a substrate main body, and then the film of the photosensitive resin is exposed to light in a predetermined pattern, and then developed, so that the surface has an uneven shape having an alignment function. A method for manufacturing a substrate for liquid crystal elements that forms a film. 3. The substrate for a liquid crystal element according to claim 1, wherein the photosensitive resin is a photosensitive polyimide resin. 4. The method for manufacturing a substrate for a liquid crystal element according to claim 2, wherein the photosensitive resin is a photosensitive polyimide resin.