JPH05158053A - Liquid crystal display manufacturing method - Google Patents

Abstract

PURPOSE:To attain a uniform thickness and to form a uniform oriented film even around the protrusion of a spacer by forming the spacer of resin on a substrate and then forming the oriented film by vacuum-deposition polymerization. CONSTITUTION:A spacer 35 of resin or a spacer 35 fixed by resin is formed on a substrate 30, and then an oriented film 32 is formed by vacuum-deposition polymerization. In the polymerization, the raw monomer of polyimide is vaporized to form a polyamic acid film on the surface of the substrate 30 on the electrode side, and then the polyamic acid is polymerized to a polyimide. The raw monomer is vaporized in vacuum to prevent a collision between the vaporized monomers, hence the monomer vapor is directly deposited on the electrode substrate, and a uniform polyamic acid film is formed. Polystyrene, silica, acryl, nylon, etc., are exemplified as the resin composition to be used for the spacer 35.

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.

[0002]

2. Description of the Related Art An example of a conventional liquid crystal display device will be described with reference to FIG. Transparent electrode 52 on glass substrate 51a
The substrate 59 is formed by forming a, an insulating film 53a, and an alignment film 54a in this order. Here, the transparent electrode 52a is formed by arranging a plurality of transparent electrodes in a stripe shape so as to be parallel to each other, and the alignment film 54a has a uniaxial alignment treatment.

On the other hand, the transparent electrode 52b, the insulating film 53b, and the alignment film 5 are also formed on the other side of the glass substrate 51b under the same conditions.
The substrate 60 is one in which each layer is formed in the order of 4b.
Similar to the substrate 59, the transparent electrode 52b and the alignment film 54b are formed by arranging a plurality of transparent electrodes in a stripe shape so as to be parallel to each other, and the alignment film 54b is subjected to uniaxial alignment treatment. It is structured.

Next, the alignment films 54a and 54b of the substrates 59 and 60 are opposed to each other, and the substrates 59 and 60 are formed.
D / p so that the twist angle of the liquid crystal composition becomes a desired value.
₀ (= cell thickness / natural pitch) and the direction in which the tilt angle occurs are matched. The cell thickness d is pasted with the seal member 56 at an interval of 2 to 8 μn. These substrates 59,
A liquid crystal composition 57 is interposed between 60 to form a liquid crystal cell 61.

Here, the liquid crystal composition 57 is filled between the two upper and lower alignment films, and its thickness (d) depends on the design and configuration of the liquid crystal display device.
It is about 20.0 μm, preferably 5.0 to 8.0 μm. However, such a wide interval is TN (twisted
Although necessary for a nematic liquid crystal, if a ferroelectric liquid crystal (hereinafter referred to as FLC) using a chiral smectic C phase is used, it is required to be 3 μm or less, generally 2 ± 0.5 μm.

Conventionally, when a known TN liquid crystal is filled in the space of 10 μm by using surface elasticity, a spacer for controlling this space has been devised. That is, the spacer is generally a spherical particle of an organic resin, for example, Micropearl SP-210 (average particle size 10.0 ± 0.5 μm).
Is used. This micropearl is a divinylbenzene-based cross-linking polymer and is a transparent true sphere particle.

However, when the transparent substrate is mechanically stressed from the outside in the display portion, that is, in the region where the liquid crystal 57 is filled, or due to the lack of flatness of the substrate, the two transparent electrodes are short-circuited with each other or Easy to approach. As a result, the liquid crystal is not translucent, and a part of the liquid crystal is blackened, and defects are likely to occur. For this reason, other micro pearl spacers are also scattered in the liquid crystal part to keep the respective electrodes at a constant distance so as not to short-circuit.

However, the spacers were merely scattered on the alignment film, and each of them made point contact with each other, and a large local load was applied to this contact portion. And, if there is an active element at this contact portion, this element may be destroyed. Therefore, it has been devised that a linear "shell" spacer is formed only in an insulating region between electrodes for preventing point concentration and stress concentration.

On the other hand, there are two conventional methods for forming an alignment film: a printing method and spin coating. However, until now, since the spacers were scattered after forming the alignment film, there is no particular problem even when the alignment film is formed using these methods, and good alignment is obtained. Had been obtained. However, in order to secure the cell gap with high accuracy, higher accuracy can be obtained by forming spacers as compared with the method of spraying spacers, and thus this method has been established.

[0010]

Among the conventional techniques, in the printing method, when the alignment film is formed on the substrate on which the spacer is previously formed, the protrusion of the spacer formed on the substrate causes There is a drawback that the alignment film is not formed. Further, the spin coating method has a drawback that unevenness in coating of the alignment film occurs due to the convex portion of the spacer formed on the substrate because it is caused by centrifugal force.

[0011]

According to the present invention, a transparent electrode and an alignment film for covering the transparent electrode are formed on a pair of translucent substrates, which face each other, and a spacer made of resin is formed on at least one of the substrates. Alternatively, in manufacturing a liquid crystal display device in which a spacer fixed by a resin is provided and a liquid crystal is sandwiched, a spacer made of a resin or a spacer fixed by the resin is formed on at least one substrate in advance, and then an alignment film is formed by a vacuum evaporation polymerization method. And a liquid crystal display device manufacturing method.

Examples of the diamine component which is easily sublimated in the condensation polymerization used in the above vacuum vapor deposition polymerization method include 1,4-phenylenediamine, diaminodiphenyl ether, diaminodiphenylmethylene and the like. Of these, diaminodiphenyl ether and diaminodiphenylmethylene are preferred.

As the tetracarboxylic acid component which easily sublimes, pyromellitic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic acid, 1,2,3,4-cyclopentanetetracarboxylic acid, 2,3 , 5-Tricarboxycyclopentylic acid, 3,5,6-tricarboxy-
Norbornane-2-acetic acid, 5- (2,5-dioxotetrahydrofuryl) -3-methyl-cyclohexene dicarboxylic acid, bicyclo- (2,2,2) -oct-7-
Examples include ene-tetracarboxylic acid, 1,2,3,4-furantetracarboxylic acid, and 3,3 ′, 4,4′-perfluoroisopropylidenetetracarboxylic acid. Of these, pyromellitic dianhydride is preferable.

It is possible to form an alignment film such as polyamide, polyurea, or polyurethane by selecting the type of monomer, but polyimide is the most excellent in terms of alignment stability. As a device for carrying out the above-mentioned polymerization reaction, a known device such as that disclosed in JP-A-61-78463 can be used.

In this apparatus, the raw material monomer of polyimide is evaporated in vacuum to form a polyamic film on the electrode side surface of the electrode substrate, and the polyamic can be polymerized to polyimide. Here, the evaporation of the raw material monomers of the polyimide in a vacuum is to prevent the evaporated monomers from colliding with each other or the inner wall of the polymerization apparatus, and to deposit the monomer vapor directly on the electrode substrate to form a uniform polyamic film. 1 × 10 ⁻⁶ Tor in general
Set the degree of vacuum to about r.

Further, the polyimide polymerized by the method using glow discharge together exhibits liquid crystal orientation. This is because ions and electrons generated during glow discharge are incident on the surface of the polyamic film at an angle close to horizontal due to the electric field, which produces the same effect as the rubbing treatment and is polymerized to polyimide in that state. Conceivable. Further, when it is necessary to heat the monomer that undergoes the polymerization reaction, a method of using a monomer kept warm in advance or a method of heating the substrate after being deposited on the substrate at room temperature is applied.

That is, in order to promote sublimation into a vacuum, the tetracarboxylic acid monomer side is heated to 16 by a heat source for heating the substrate.
It is preferable to heat to about 0 ° C. and to heat the diamine monomer to about 140 ° C. Further, in order to promote the polyamic reaction, it is preferable to heat the electrode substrate to 40 ° C. or higher. As a ready-made vacuum vapor deposition polymerization apparatus, a vacuum vaporization polymerization apparatus VEP-100A type manufactured by Nippon Vacuum Technology Co., Ltd. can be used.

The resin composition used for the spacer includes polystyrene, silica, acrylic, vinylidene chloride, nylon and the like. Of these, polystyrene and silica are preferably used. When the spacer shape is not fixed to the substrate, it is appropriate that the stress concentration is as small as possible.
The shape of a sphere, cylinder or ellipsoid is good. When it is used by being fixed on a substrate, a spherical or ellipsoidal shape is suitable.

The size of the spacer is 1 to 30 μm, but 4 to 15 μm is preferable.

[0020]

According to the present invention, a film having a uniform orientation can be formed around the convex portions of the spacer formed on the substrate.

[0021]

EXAMPLES The present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

Example 1 Here, the present invention will be described in detail, limited to the vicinity of the spacer of the present invention. FIG. 1 shows a cross-sectional view near the thin film transistor. Here, 1 is a gate electrode 2, 2 is a gate insulating film, 3 is an amorphous silicon semiconductor film, 4 is an n + -amorphous silicon film, 5 is a source electrode, 6 is a drain electrode, 7 is a pixel electrode, 8 is a protective film, and 9 is Transparent electrode, 10 is an insulating film, 1
Reference numeral 1 is an alignment film, 12 is a light-shielding film made of a colored resin, 13 is a liquid crystal, and 14 is a substrate. First, a gate electrode (tantalum in this embodiment) is formed by using aluminum, tantalum, titanium, copper or the like on a substrate made of glass, quartz or the like,
A gate insulating film (silicon nitride in this embodiment) was formed using silicon nitride, silicon oxide, or the like. Then C
Amorphous silicon semiconductor film using VD, and n
After forming the ⁺ -amorphous silicon film, a source electrode and a drain electrode (titanium in this embodiment) were formed using aluminum, tantalum, titanium, copper, or the like. After forming the thin film transistor in this manner, a pixel electrode was formed using ITO. A protective film (silicon oxide in this embodiment) was formed on top of it by using silicon nitride, silicon oxide, or the like. This protective film is not particularly necessary, but the effect of preventing characteristic deterioration when the insulating property of the colored resin film is not very high or the film of the colored resin film contains ionic impurities There is. Here, a light shielding film made of a colored resin is formed. As this colored resin, there is a color mosaic CK (trade name: manufactured by Fuji Hunt Electronics Technology Co., Ltd.) as a product, but in addition, a product obtained by coloring polyimide, polyamide, polyamic acid, acrylic or the like with carbon, dye, pigment or the like is used. It is possible (color mosaic CK in this example). When using color mosaic CK, spin coat 1400 rpm, 1
A film thickness of about 1 μm can be applied in 0 seconds, and the visible light transmittance in this case is about 1.7% at 550 nm. Here, since this light-shielding film is used as a spacer, the film thickness is set to 5 μm.

Example 2 FIG. 2 shows a schematic view of an apparatus for forming a liquid crystal molecular alignment film of the present invention. Here, 15 is a crucible A for monomers, 1
6 is a crucible B for a monomer, 17 is a monomer A, 18 is a monomer B, 19 is a heat source A for heating a monomer, 20 is a heat source B for heating a monomer, 21 is a shutter A, 22 is a shutter B, 23 is a mask for a substrate, 24 Is a substrate, 25 is a formed liquid crystal molecular alignment film, 26 is a substrate heating source, 27 is a bell jar, 28 is a monomer recovery trap, and 29 is a vacuum pump.

First, the monomers A and B and the substrate were set at predetermined positions in the bell jar, and the inside of the bell jar was set to 10 ^-5 T.
After applying a vacuum of orr or lower, heat sources A and B for heating the monomer
And the substrate heating source is activated to sublimate each monomer. When the substrate reaches 40 ° C and the temperature of the monomer reaches the specified value (160 ° C and 140 ° C for pyromellitic dianhydride and diaminodiphenyl ether), the shutter is opened, and the polymer liquid crystal molecular alignment film is formed on the substrate. Evaporate and polymerize. When the polymer film reaches the film thickness (800Å), the shutter is closed, the heat source is turned off, the inside of the bell jar is returned to normal pressure, and then the substrate is taken out to form a liquid crystal molecule alignment film on the substrate. Here, when polyimide is used as the alignment film, pyromellitic dianhydride is used as the monomer A, and diaminodiphenyl ether is used as the monomer B, and the sublimation may be performed at a stoichiometric ratio. The film thickness is about 600 to 1000Å (800Å in this embodiment). However, in the case of polyimide, since it is a polyamic acid at the stage of vapor deposition polymerization, for example, in the case of obtaining pyromellitic imide, it is necessary to heat it at a temperature of about 200 ° C. for 30 minutes or more to perform an imidization reaction to obtain a polyimide. is there.

Examples 3 to 4 FIG. 3 shows the structure of the liquid crystal device produced by the present invention. Here, 30 is a glass substrate, 31 is a transparent conductive film, 32 is an alignment film formed by the method of the present invention, 33 is a seal, 34
Is a liquid crystal, and 35 is a light-shielding film spacer. The substrate formed by the above method and the substrate on which the alignment film is formed on the transparent conductive film are subjected to the alignment treatment by the rubbing method, and then a seal is formed on one of the substrates and the two substrates are bonded to each other. After injecting, the liquid crystal device was obtained by sealing the injection port.

The liquid crystal applied here is ZLI-1.
565, ZLI-4217, ZLI-4353 and the like. (ZLI-1565 in Example 3, Example 4
ZLI-1565)

Example 4 is shown in FIG. 36 here
Is a glass substrate, 37 is a transparent conductive film, 38 is an alignment film formed by the method of the present invention, 39 is a seal, 40 is a liquid crystal,
Reference numeral 41 is a spacer, and 42 is a light shielding film. Here, when the light-shielding film according to the first aspect is formed, spacers (diameter 5 μm) of 3 wt% are mixed in the resin to form the light-shielding film with the spacers fixed. At this time, the thickness of the light-shielding film is preferably 2 to 3 μm because the spacer can be fixed and sufficient light-shielding property is required.

Table 1 shows the results of comparing the cell thicknesses between the fabrication methods of Examples 3 and 4 and the conventional printing method and spin coater method.

[0029]

[Table 1]

As can be seen from Table 1, the method of the present invention has a smaller variation in thickness than any of the conventional methods, and a uniform cell thickness is obtained. When a liquid crystal display device was produced by the above method, a uniform cell thickness was obtained in each case and perfect alignment was obtained.

[0031]

The liquid crystal display device manufactured according to the present invention has a uniform cell thickness and a perfect orientation, and thus has a good display quality for direct-view displays, high-definition projectors and the like. can get.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of the vicinity of a thin film transistor according to an embodiment of claim 1 of the present invention.

FIG. 2 shows a schematic view of an apparatus for forming a liquid crystal molecular alignment film of the present invention.

FIG. 3 shows a schematic structure of a liquid crystal device prepared according to the present invention.

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

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

[Explanation of symbols]

1 gate electrode 2 gate insulating film 3 amorphous silicon semiconductor film 4 n ⁺ -amorphous silicon film 5 source electrode 6 drain electrode 7 picture element electrode 8 protective film 9 transparent electrode 10 insulating film 11 alignment film 12 light-shielding film 13 with colored resin 13 liquid crystal 14 Substrate 15 Monomer crucible A 16 Monomer crucible B 17 Monomer A 18 Monomer B 19 Monomer heating heat source A 20 Monomer heating heat source B 21 Shutter A 22 Shutter B 23 Substrate mask 24 Substrate 25 Formed liquid crystal molecular alignment film 26 Substrate heating Heat source 27 bell jar 28 monomer recovery trap 29 vacuum pump 30 glass substrate 31 transparent conductive film 32 alignment film formed by the method of the present invention 33 seal 34 liquid crystal 35 spacer 36 glass substrate 37 transparent conductive film 38 by the method of the present invention Alignment film 39 seal 40 Liquid crystal 41 Spacer 42 Light-shielding film 51a, 51b Glass substrate 52a, 52b Transparent electrode 53a, 53b Insulating film 54a, 54b Alignment film 56 Seal member 57 Ferroelectric liquid crystal composition 59, 60 Substrate 61 Liquid crystal cell 62a, 62b Polarizing plate

Claims (2)

[Claims] 1. A pair of translucent substrates each having a transparent electrode and an alignment film covering the transparent electrode formed on its opposing surfaces, and a spacer made of resin or a spacer fixed by the resin is provided on at least one of the substrates. In the manufacturing of the liquid crystal display device in which the liquid crystal is sandwiched, the spacers made of resin or the spacers fixed by the resin are formed on at least one substrate in advance, and then the alignment film is formed by the vacuum vapor deposition polymerization method. Liquid crystal display device manufacturing method. 2. The method according to claim 1, wherein the resin forming the spacer or the resin fixing the spacer is colored.