JPH1096931A - Liquid crystal oriented film and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal oriented film which imparts uniform and high pretilt angles to liquid crystal molecules and has high reliability and a process which provides this oriented film with a simple stage and easily increases the dielectric constant of the liquid qrystal oriented film. SOLUTION: The halogen element content of the molecules constituting the film surface of the liquid crystal oriented film 41 formed on a substrate 61 is higher than the halogen element content of the molecules constituting the part near the substrate boundary or the inside of the film with this liquid crystal oriented film and the process for producing the same. The surface of the liquid crystal oriented film is irradiated with the charges or neutral particle fluxes consisting of the halogen element as their constitute elements, by which the high pretilt angles are imparted to the liquid crystal molecules. The halogen element described above is fluorine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquid crystal alignment film used for a liquid crystal display device.

[0002]

2. Description of the Related Art At present, an active matrix type liquid crystal display device having a thin film transistor element in each pixel is widely used as a high performance color display device. In this method, an electric field generated between a signal line (or gate line) and a pixel electrode causes an abnormal alignment region called reverse tilt discrimination. In order to reduce the abnormal alignment region, it is necessary to set the pretilt angle of the liquid crystal molecules to 2 degrees or more so that reverse tilt does not occur. In a super twisted nematic (STN) system widely used as a display device such as a word processor, liquid crystal molecules are twisted by about 240 degrees. In order to stably obtain the twist of about 240 degrees, it is necessary that the liquid crystal alignment film has a pretilt angle of 4 degrees or more. In addition, twisted state nematic (T
The N) method has the advantage that the drive voltage is reduced and the response speed is increased by increasing the pretilt angle. If a pretilt angle of about 10 degrees or more can be stably obtained over the entire display screen, OCB, HA
New display modes such as N, π cell, 180 degree twist π cell, bend alignment cell, and splay alignment cell can be realized. For these reasons, studies have been made on liquid crystal alignment films that can provide high pretilt angles to liquid crystal molecules.

[0003]

As a method of giving a high pretilt angle to liquid crystal molecules, there is a method of introducing a hydrophobic functional group into a liquid crystal alignment film. Examples of the hydrophobic functional group include a long-chain alkyl group, a cholesteryl group, a functional group having a fluorine element such as CF ₃ , and a functional group having a skeleton similar to a liquid crystal molecule such as biphenyl. The position where the hydrophobic functional group is introduced is a side chain, a main chain, or a terminal group of polyamic acid or soluble polyimide. The mechanism of developing the pretilt angle of the liquid crystal molecules can be explained by the effect of the surface tension of the liquid crystal alignment film. In other words, a liquid crystal alignment film having a low surface tension (a liquid crystal alignment film having a high degree of hydrophobicity) exhibits a high pretilt angle because repulsion with liquid crystal molecules is large.
Therefore, by introducing a hydrophobic functional group into the liquid crystal alignment film, the pretilt angle of the liquid crystal molecules can be increased.

The pretilt angle increases almost in proportion to the amount of the hydrophobic functional group introduced. As a result of intensive studies by the inventors, when the amount of the hydrophobic functional group introduced is increased so that the pretilt angle becomes 5 degrees or more, the solution (varnish) of the liquid crystal alignment film becomes hydrophobic (lipophilic), and It was found that the wettability was worse. As a result, the substrate cannot be uniformly applied (printed) by repelling the liquid crystal alignment film solution,
There has been a problem that the thickness of the liquid crystal alignment film after firing becomes uneven. This unevenness in film thickness significantly deteriorated the display quality of the liquid crystal display device.

Further, it has been found that introduction of a hydrophobic functional group into the side chain or terminal of the liquid crystal alignment film is easier to synthesize than introduction into the main chain, but has the following problems.

The liquid crystal alignment film is obtained by applying a liquid crystal alignment film solution to a substrate and volatilizing a solvent in a hot plate or an oven. When air is more hydrophobic when the substrate and air are compared, the side chains and terminal groups rotate toward the air side during solvent evaporation, and extend almost perpendicularly from the substrate surface. This tendency becomes remarkable when the solvent evaporates after the application of the alignment film solution. When there is a temperature distribution on a hot plate or in an oven, or when air is blowing on a substrate, unevenness occurs in the evaporation rate of the solvent in one substrate soil. The solvent evaporates faster in the region where the temperature is high or where the wind is applied, so that the amount of side chains or terminal groups extending vertically from the film surface is smaller than in the other region. Therefore, the pretilt angle of the liquid crystal molecules in this region decreases. When the pretilt angle is reduced, the voltage-transmittance characteristic changes, resulting in display unevenness in the liquid crystal display device.

Further, when the surface of the alignment film is stretched by rubbing and the main chains of the alignment film molecules are aligned in the rubbing direction, the conformation of the hydrophobic side chains (terminal groups) also changes. Before rubbing, a hydrophobic side chain (terminal) group extends almost vertically from the film surface. When rubbing is performed, with the conformational change of the main chain of the alignment film molecule,
The hydrophobic side chain (terminal) group extending vertically from the film surface enters the inside of the film (substrate side). As a result, the pretilt angle decreases. This means that the margin of the pretilt angle for rubbing is narrow.

As described above, it is difficult to obtain a high pretilt angle such as 5 degrees or more (especially 8 degrees or more) uniformly over the entire surface of the substrate by the conventional method.

The present invention solves these problems and provides liquid crystal molecules with a uniform and high pretilt angle over the entire surface of the substrate.
It is another object of the present invention to obtain a highly reliable liquid crystal alignment film and provide the film in a simple process. Another object of the present invention is to provide a method for easily increasing the dielectric constant of a liquid crystal alignment film. In addition, there is no unevenness in the image, the image is hardly burned,
It is an object to provide a high-quality liquid crystal display device.

[0010]

To achieve the above object, the present invention provides a liquid crystal alignment film formed on a substrate,
It is an object of the present invention to provide a liquid crystal alignment film characterized in that the halogen element content in the molecules constituting the film surface is larger than the halogen element content in the molecules constituting the vicinity of the substrate interface or inside the film.

Further, in the alignment film formed on the substrate, the halogen element content in the molecules constituting the film surface is 2%.
% Or more, and the content of a halogen element in molecules constituting the vicinity of the substrate interface is less than 2% to obtain a liquid crystal alignment film.

Further, a method for producing a liquid crystal alignment film characterized by imparting a high pretilt angle to liquid crystal molecules by irradiating the surface of the liquid crystal alignment film with a charged particle or a neutral particle bundle containing a halogen element as a constituent element. What you get.

Further, the present invention provides a liquid crystal alignment film and a method of manufacturing the liquid crystal alignment film, wherein the halogen element is fluorine.

In this case, it is preferable to use NF ₃ or CF ₄ as a gas source for the charged particles or neutron particles. Further, the present invention provides a method for producing an alignment film in which charged particles or neutron particles are irradiated to the rubbed liquid crystal alignment film surface.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, the surface of the liquid crystal alignment film is made hydrophobic by irradiating the liquid crystal alignment film formed on the substrate with a charged particle or a neutral particle bundle containing a halogen element.

The halogen element is F, Cl, Br or the like. The charged or neutral particle flux includes an ion beam, plasma, and the like. In the present invention, irradiation with a charged or neutral particle flux is referred to as plasma treatment or ion beam irradiation, but is not limited thereto. Assuming that the halogen element is X, charged or neutral particles include X ⁺ ion, X ⁻ ion, excited X atom, excited molecule having X as a constituent, cation having X as a constituent, and X as a constituent Anions and the like are included.

As an example, FIG. 1 shows the relationship between the plasma processing time and the surface energy of the alignment film (reaction gas: NF ₃
(0.2 Torr), 900 cm ² parallel plate electrode, distance between electrodes: 3.5 cm, applied voltage: 13.56 MHz,
15W, alignment film material: polyimide (Nissan Chemical SE-15
0). As the processing time increases, the surface energy decreases, and the surface of the alignment film becomes hydrophobic. This tendency did not change even when the reaction gas, the material of the alignment film, the electrode shape, the applied voltage, and the like were changed.

As a gas used to form a charged particle bundle or a neutral particle bundle, NF ₃ , CF ₄ , C ₃ F ₈ , Xe
F ₂ , NHF ₂ , NH ₂ F, NCl ₃ , NHCl ₂ , N
H ₂ Cl, CHF ₃ , CH ₂ F ₂ , CH ₃ F, CC
_{l 4, CHCl 3, CH 2} Cl 2, CHCl 3 ... and the like.

In particular, NF ₃ , CF ₄ , and XeF _{2, which} are gases made of molecules containing elemental fluorine, are preferred.

In charged or neutral particle bundles such as plasma, radicals such as fluorine atoms and chlorine atoms and excited atoms and ions are generated, and these radicals collide with the alignment film surface. C, C, C in the alignment film molecules on the alignment film surface due to the collision
Bonds such as —H, C—O—C, C ＝ O, and C—N are broken, and then re-bonded with the fluorine atom or chlorine atom (C-
F). As a result, the following polymer is generated.

[0021]

Embedded image

Embedded image

Embedded image The surface of the alignment film is hydrophobized by the action of the fluorine atoms and chlorine molecules introduced as described above.

The content (composition ratio) of the introduced halogen element can be evaluated by XPS (X-ray photoelectron spectroscopy). In XPS, the depth of the detected electrons can be changed by changing the detection angle. For example, at a detection angle of 5 degrees, about 9 A from the sample surface (hereinafter, Angstroms is represented by A), and at a detection angle of 45 degrees, about 7 A from the sample surface.
The elemental composition of 0A can be known. The alignment film irradiated with the charged or neutral particle flux is subjected to XPS analysis, and the composition ratio (%) of each element is determined with the detected total element amount being 100%. If the composition ratio of the halogen element at the detection angle of 1 to 10 degrees is larger than the composition ratio of the halogen at the detection angle of 45 to 90 degrees, the halogen element content (composition ratio) in the molecules constituting the film surface becomes closer to the substrate interface. Or it can be said that it is larger than the halogen element content (composition ratio) in the molecules constituting the inside of the film.

Further, SIMS (Secondary Ion Mass Spectrometry)
It is also possible to analyze the amount of the halogen element in the alignment film. By performing SIMS measurement while sputtering the alignment film, it is possible to evaluate the halogen element amount on the alignment film surface and inside the alignment film (bulk).

FIG. 2 shows the relationship between the plasma processing time and the pretilt angle, and FIG. 3 shows the relationship between the surface energy and the pretilt angle when performing the plasma processing. As can be seen from the figure, increasing the plasma processing time increased the pretilt angle. Hydrophobic orientation film by plasma treatment
A high pretilt angle of 0 degree or more could be given to the liquid crystal molecules. In addition, plasma processing conditions (processing time, power)
By changing the angle, an arbitrary pretilt angle could be obtained.

As shown in FIG. 4A, when the charged particles or the neutral particles are irradiated, the reactive particles collide with the surface of the alignment film 41 and do not diffuse into the alignment film. Therefore, the area 42 that is hydrophobized by irradiation of the charged or neutral particle bundle
Is 150 A at most from the alignment film surface. If the thickness of the liquid crystal alignment film is 200 A or more, the alignment film in the vicinity of the substrate 43 is not hydrophobized even when the charged or neutral particle flux is irradiated, and thus the adhesion to the substrate is good (FIG. )reference).
Actually, the halogen element-containing effect in the molecules constituting the film surface is determined by the composition ratio within 10% of the film thickness when viewed from the surface, and the halogen element-containing effect in the molecules constituting the vicinity of the substrate interface is determined from the substrate. As a result, the thickness is less than 10% of the film thickness.

On the other hand, when the alignment film material 44 is made hydrophobic by bonding a halogen atom or the like to the alignment film molecule as shown in FIG. 4B, the vicinity 45 of the interface with the substrate 43 also becomes hydrophobic. Adhesion (wetting property) of the polymer decreased. When the adhesion is reduced, there is a problem that the alignment film is peeled off when the alignment film is rubbed or when the substrate is heated by curing the sealing agent.

Irradiation of a charged or neutral particle flux can be performed uniformly on a large-area substrate, as can be seen from the results of forming amorphous silicon for large-scale integrated circuits (LSIs) and liquid crystal display elements. it can. In the present invention,
A uniform and high pretilt angle could be obtained over a large area of about 500 mm × 600 mm.

Since the molecules of the alignment film and the halogen atoms are chemically bonded by the irradiation of the charged or neutral particle bundle, even if the liquid crystal display device having the alignment film of the present invention has been used for 8 years or more,
The pretilt value does not change, and a high pretilt angle can be stably provided for a long time according to the present invention.

In the alignment film having a hydrophobic functional group introduced into a side chain (terminal), the pretilt angle changes as shown by a curve B in FIG. 5 when the rubbing strength is changed. This phenomenon is explained as shown in FIG. Before the rubbing treatment, the hydrophobic side chain (terminal) group 52 extends almost vertically from the alignment film molecule main chain 51 on the film surface. When the rubbing treatment is performed, the hydrophobic side chain (terminal) group 52 extending vertically from the film surface enters the inside (substrate side) of the film due to the conformational change of the alignment film molecule main chain 51. As a result, the pretilt angle decreases.

On the other hand, in the alignment film of the present invention, a halogen atom (ion) is mainly bonded to the main chain of the alignment film molecule.
Therefore, even if the rubbing strength is changed, the surface energy (halogen element content) of the alignment film surface does not change, and thus the pretilt angle hardly changes. This relationship is shown in curve A of FIG. As a result, in the production of the liquid crystal display device, even if the rubbing condition was changed due to a defect of the rubbing device, the yield could be improved without changing the pretilt angle.

Further, since the surface of the liquid crystal alignment film was made hydrophobic by irradiation with the charged or neutral particle bundle, the alignment film became difficult to absorb water. When polyvinyl alcohol or the like is used as the alignment film material, there is a problem that the alignment film absorbs moisture and the rubbing effect is deteriorated, or the alignment film is dissolved. When polyimide or the like is used as the alignment film material, there is a problem that the polyimide absorbs moisture and hydrolyzes to change the dielectric constant and the pretilt angle, thereby deteriorating the display quality. According to the alignment film of the present invention, since the surface is made hydrophobic, water absorption is less likely to occur, and the reliability of the liquid crystal alignment film can be improved.

If the same image is displayed on the liquid crystal display for a certain period of time, there is a defect called "burn-in" in which the previous display appears to remain thin when changed to the next display. Image sticking occurs when ionic impurities contained in the liquid crystal are adsorbed on the liquid crystal alignment film. In the liquid crystal alignment film of the present invention, since the surface of the alignment film is made hydrophobic, ionic impurities are less likely to be adsorbed on the alignment film, and the image sticking failure can be prevented.

As in the present invention, when the surface of the liquid crystal alignment film is halogenated by irradiation with a charged or neutral particle bundle,
The polarizability of the alignment film was increased, and the dielectric constant of the alignment film could be increased. As a result, when the dielectric constant of the alignment film increases, the effective voltage applied to the liquid crystal increases, so that the driving voltage of the liquid crystal display device can be reduced.

Further, by irradiating fluorine (or chlorine) atom radicals in the plasma from obliquely to the substrate on which the alignment film is formed, or by using a mask having a plurality of rectangular openings, rubbing can be performed. In addition, the liquid crystal molecules could be aligned in one direction with a constant pretilt angle.

By partially irradiating the charged or neutral particle flux, a wide viewing angle called a dual domain can be obtained. That is, the first substrate is irradiated with the charged or neutral particle flux (high pretilt angle) and the second substrate is not charged or irradiated with the neutral particle flux (low pretilt angle). The liquid crystal with the charged or neutral particle flux irradiated on the second substrate (high pretilt angle) and the charged or neutral particle flux non-irradiated (low pretilt angle) region on the first substrate are opposed to each other. Form cells. Thereby, the rising directions of the liquid crystal molecules when voltage is applied are different.
Since two regions are formed and these portions compensate for each other's viewing angles, a liquid crystal display device having a wide viewing angle can be manufactured.

As a plasma method, a parallel plate type, a magnetic field type, and an electron cyclotron resonance type can be applied. By confining the plasma with a magnetic field, the processing time for hydrophobization can be reduced. The pressure of the reaction gas is 0.05 to 1
0 Torr is preferable, and high frequency (13.56 MHz) power is preferably 1 W to 300 W (particularly 3 to 100 W).

In the present invention, the alignment film is made of polyimide,
Polyamide, BCB (Penzocyclobutene polymer),
A transparent organic thin film such as polyvinyl alcohol is preferred. In particular, a polyimide film obtained by imidizing a polyamic acid synthesized from the following diamine and acid anhydride is preferable.

Acid anhydrides: aliphatic and alicyclic tetracarboxylic dianhydrides such as butanetetracarboxylic dianhydride and 2,3,5-tricarboxycyclopentylacetic dianhydride, pyromellitic dianhydride, etc. Aromatic tetracarponic dianhydride.

Diamine: p-phenylenediamine, 4,
Aliphatic or alicyclic diamines such as 4'-diaminodiphenylmethane;

[0040]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) A first embodiment of the present invention will be described with reference to FIG.

First, as shown in FIG.
A gate metal 62a made of a MoTa alloy was formed thereon by using a magnetron butter method. Next, the gate oxide film 6
A gate insulating film made of 2b and silicon nitride was formed.
An a-Si film 62c and a channel protection film 62d made of silicon nitride were formed thereon by a CVD method.

A-Si by patterning and etching
After the islands were formed, an ohmic layer was formed. afterwards,
A pixel electrode 63 was formed, and source and drain electrodes made of Mo / Al were formed. In this way, the TFT
62 is completed. Finally, a silicon oxide protective layer (passivation film) 64 having a thickness of 2500 angstroms was formed on the TFT.

A solution prepared by dispersing a red pigment in a photosensitive BCB varnish was applied on a second substrate (not shown), and a portion for forming a red color filter was exposed.
Thereafter, the non-exposed portions were removed with a developer to form a red color filter. Similarly, blue and green color filters were formed on the second substrate. A transparent electrode of indium tin oxide (ITO) was formed on the entire surface of the substrate on which the color filter was formed. Photosensitivity B
Color filters using CB are excellent in chemical resistance and heat resistance.

As shown in FIG. 7B, a first substrate 61 having a TFT 62 (hereinafter referred to as a substrate 61 including a TFT 62, a pixel electrode 63, and a protective film 64) and a second substrate having a color filter are provided. A soluble polyimide (AL-1051 manufactured by Nippon Synthetic Rubber Co., Ltd.) was printed thereon as an alignment film 41, and was further heated at 80 ° C. for 1 minute using a hot plate.
_The mixture was baked at 180 ° C. for 30 minutes in an oven to evaporate the solvent. The thickness of the polyimide was 500 angstroms.

As shown in FIG. 7C, a polyimide alignment film 41 is formed.
The first substrate 61 and the second substrate on which the pattern was formed were rubbed in one direction, for example, in the direction of the arrow. The rubbing cloth used was made of rayon and had a hair tip diameter of 0.1 to 10 microns. The rubbing conditions were as follows: roller rotation speed 500 rpm, substrate moving speed 50 mm / s, pushing amount 0.5 mm,
The number of rubbings is one. The substrate was washed with an aqueous solution containing a neutral surfactant as a main component to remove attached dirt (such as rubbing cloth hair) from the rubbing cloth.

The first and second substrates rubbed as shown in FIG. 7D were placed in a plasma chamber 70 as shown in FIG. 8, and the surface of the alignment film was subjected to a hydrophobic treatment. More specifically, these substrates are placed in a chamber evacuated to 10 ^-6 Torr, and NF ₃ gas is introduced thereinto for 0.2 Torr.
r, parallel plate electrodes 71, 7 having an electrode area of 900 cm ²
2. Distance between electrodes: 3.5cm, applied voltage: 13.56M
The plasma treatment was performed at 15 Hz for 2 minutes (FIG. 7).
Arrows in (d) schematically show ion irradiation).

The electrode 72 on which the substrate on which the alignment film was formed was grounded, and a high-frequency voltage was applied to the opposite electrode 71 so that the alignment film was not etched by the ions accelerated by the electric field. This substrate was placed in an N ₂ oven at 180 ° C., 3
It was baked for 0 minutes, and further washed with an aqueous solution mainly containing a neutral surfactant. Thus, the NF ₃ gas physically adsorbed on the alignment film surface was removed. Note that in FIG.
Denotes a substrate carry-in port, and reference numeral 74 denotes a carry-out port.

Next, as shown in FIG. 7E, an epoxy-based seal in which 5 μm diameter spacer particles 65 are scattered on the first substrate 61 and a 5 μm diameter fiber is mixed around the second substrate 66. Material 67 was applied. The first substrate 61 and the second substrate 66 are opposed to each other, the upper and lower substrates are accurately aligned, and the two opposed substrates are placed in an oven while being pressed, and heated at 160 ° C. for 3 hours. Thereby, the sealing material 67 was completely cured, and the first substrate and the second substrate were bonded to form a cell. After the chiral nematic liquid crystal material 68 was injected into this cell, the injection port was cured with an epoxy-based adhesive. A drive circuit was mounted thereon to produce a TN type liquid crystal display device having a diagonal of 9 inches.

When the pretilt angle of this liquid crystal display device was measured, a uniform pretilt angle of 20.0 degrees ± 0.1 was obtained over the entire surface of the substrate. As a result, there was little edge reverse generated when a voltage was applied to the electrode, and a contrast of 200: 1 could be obtained hidden by the black matrix portion. This pretilt angle did not change even after a 500-hour driving test under a high temperature and high humidity condition of a temperature of 80 ° C. and a humidity of 90%.

The adhesion between the alignment film 41 and the substrates 61 and 66 was good, and the alignment film was not peeled off during rubbing even in the 1.5 μm-high uneven portion where the TFT element 62 was formed.

The liquid crystal display of this example had good liquid crystal alignment, voltage holding ratio, and contrast, and display quality was good even after driving for 5000 hours. Also, the resistivity is 10 ⁻¹² Ω
Even when a liquid crystal material containing a relatively large amount of impurity ions of cm was used, no burn-in failure occurred.

Further, the relative dielectric constant of the alignment film was increased from 3.0 to 3.8 by the plasma treatment of this embodiment, and the driving voltage of the liquid crystal display device could be reduced.

The alignment film of this example was analyzed by XPS using characteristic X-rays of Al. 12 ° and 90 ° detector angles
And from the surface of the sample about 20 A and about 100 A, respectively.
Was determined.

The average composition ratio of the F element from the sample surface to a depth of about 20 A was 5%, and the average composition ratio of the F element from the sample surface to a depth of about 100 A was 1%. That is,
The halogen element content (composition ratio) in the molecules constituting the film surface is larger than the halogen element content (composition ratio) in the molecules constituting the vicinity of the substrate interface or inside the film.

In order to exhibit the effect of the present invention, in the XPS analysis using the characteristic X-ray of Al, the angle of the detector is set to 1
Approximately 20A deep from the sample surface obtained when set to 2 degrees
The average composition ratio of F element up to 2% is preferably 2% or more (preferably 4% or more and 30% or less). In addition, when the angle of the detector is 90 degrees, the depth from the sample surface is 10
The average composition ratio of the F element up to 0A is preferably less than 2% (preferably 1% or less).

In order to provide a high pretilt angle of 5 ° or more, the halogen content (composition ratio) on the surface side of the alignment film must be 2
% Or more, preferably 4% to 50%,
The halogen content on the substrate side is preferably less than 2%, preferably 1% or less.

Example 2 Example 2 differs from Example 1 in that rubbing was performed after the plasma treatment and that the plasma conditions and the alignment film material were changed.

First, a first substrate and a second substrate similar to the first substrate 61 and the second substrate 66 of the first embodiment are prepared.

On a first substrate 61 having a TFT 62 and a second substrate having a color filter, a soluble polyimide (AL-L manufactured by Nippon Synthetic Rubber Co., Ltd.)
1051) was printed and baked at 80 ° C. for 1 minute using a hot plate at 180 ° C. for 30 minutes in a N ₂ oven to evaporate the solvent. The thickness of the polyimide was 500 angstroms.

The first and second substrates were placed in a plasma chamber, and the surface of the alignment film was subjected to a hydrophobic treatment.

More specifically, these substrates are formed at 10 ^-6 To
rr was placed in a vacuum chamber, CF ₄ gas was introduced to 0.1 Torr, a parallel plate electrode of 900 cm ² electrode, the distance between the electrodes: 3.5 cm, and the applied voltage: 13.
Plasma treatment was performed at 56 MHz and 10 W for 1 minute.

The first and second substrates subjected to the plasma treatment were subjected to a rubbing treatment. The rubbing cloth used was made of rayon and had a hair tip diameter of 0.1 to 10 microns. The rubbing conditions were as follows: roller rotation speed 800 rpm, substrate moving speed 5
The rubbing frequency is 0 mm / s and the pushing amount is 0.6 mm.

Next, spacer particles of 5 μm in diameter were scattered on the first substrate, and an epoxy-based sealing material mixed with fibers of 5 μm in diameter was applied to the periphery of the second substrate. The first substrate and the second substrate are opposed to each other, and the positions of the upper and lower substrates are accurately adjusted.
The sealing material was completely cured by heating in an oven at 160 ° C. for 3 hours, and the first substrate and the second substrate were bonded to form a cell. After injecting a chiral nematic liquid crystal material into this cell, the inlet was cured with an epoxy-based adhesive. A drive circuit is mounted on this, and a diagonal 9
An inch TN liquid crystal display device was manufactured.

When the pretilt angle of the liquid crystal display device was measured, a uniform pretilt angle of 8.0 degrees ± 0.1 was obtained over the entire surface of the substrate. As a result, the edge reverse was hidden by the black matrix portion, and a contrast of 250: 1 could be obtained. This pretilt angle did not change even after a 500-hour driving test under high temperature and high humidity at a temperature of 80 ° C. and a humidity of 90%.

The adhesion between the alignment film and the substrate was good, and the alignment film was not peeled off during rubbing even in the 1.5 μm-high uneven portion where the TFT element was formed.

The liquid crystal display device of this example had good liquid crystal alignment, voltage holding ratio and contrast, and good display quality even after driving for 5000 hours. Also, the resistivity is 10 ^-13 Ω
Even when a liquid crystal material containing a relatively large amount of impurity ions of cm was used, no burn-in failure occurred.

Further, the relative dielectric constant of the alignment film was increased from 2.7 to 3.7 by the plasma treatment of this example, and the driving voltage of the liquid crystal display device could be reduced.

As in the present embodiment, even when rubbing was performed after the plasma treatment, a good liquid crystal display device similar to that of the first embodiment could be formed.

The alignment film of this example was analyzed by XPS using characteristic X-rays of Al. 12 ° and 90 ° detector angles
And from the surface of the sample about 20 A and about 100 A, respectively.
Was determined. The average composition ratio of the F element from the sample surface to a depth of 20A was 2%, and the average composition ratio of the F element from the sample surface to a depth of 100A was 1%. That is, the halogen element content (composition ratio) in the molecules constituting the film surface is larger than the halogen element content (composition ratio) in the molecules constituting the vicinity of the substrate interface or inside the film.

Embodiment 3 Embodiment 3 differs from Embodiment 1 in that the present invention is applied to an antiferroelectric liquid crystal display device.

First, a first substrate and a second substrate similar to the first substrate 61 and the second substrate 66 of the first embodiment are prepared. On a first substrate having a TFT and a second substrate having a color filter, a soluble polyimide as an alignment film (AL-1051 manufactured by Nippon Synthetic Rubber Industries, Ltd.)
Was printed and baked at 80 ° C. for 1 minute using a hot plate at 180 ° C. for 30 minutes in a N ₂ oven to evaporate the solvent. The thickness of the polyimide was 500 angstroms.

The first and second substrates having the polyimide alignment film formed thereon were subjected to a rubbing treatment. The rubbing cloth used was made of nylon and had a hair tip diameter of 0.1 to 10 microns. The rubbing conditions are as follows: the number of rotations of the roller is 500 rpm, the moving speed of the substrate is 50 mm / s, the pushing amount is 0.5 mm, and the number of rubbing is three.

The rubbed first and second substrates were placed in a plasma chamber, and the surface of the alignment film was subjected to a hydrophobic treatment. Specifically, these substrates were placed in a chamber evacuated to 10 ^-6 Torr, and NF ₃ gas was introduced to 2 Torr, a parallel plate electrode of 900 cm ² electrode, a distance between the electrodes: 3.5 cm, and an applied voltage. : 13.56 MHz,
Plasma treatment was performed at 15 W for 10 minutes. Note that a high-frequency voltage was applied to the electrode on which the alignment film forming substrate was placed, and the counter electrode was grounded so that the hydrophobicity (halogenation) was sufficiently performed.

Next, 2 μm diameter spacer particles were scattered on the first substrate, and an epoxy sealing material mixed with 2 μm diameter fibers was applied to the periphery of the second substrate. The first substrate and the second substrate were opposed. While placing the substrate under the ground accurately, pressurizing the two opposing substrates,
The sealing material was completely cured by heating in an oven at 160 ° C. for 3 hours, and the first substrate and the second substrate were bonded to form a cell. After injecting the antiferroelectric liquid crystal material into this cell, the inlet was cured with an epoxy-based adhesive. A drive circuit was mounted thereon to produce a TN type liquid crystal display device having a diagonal of 7.5 inches.

When the pretilt angle of this liquid crystal display device was measured, a uniform pretilt angle of 5.0 degrees ± 0.1 was obtained over the entire surface of the substrate. As a result, the edge reverse was hidden by the black matrix portion, and a contrast of 100: 1 was obtained. This pretilt angle did not change even after a 500-hour driving test under high temperature and high humidity at a temperature of 80 ° C. and a humidity of 90%.

The adhesion between the alignment film and the substrate was good, and the alignment film was not peeled off during rubbing even in the uneven portion having a height of 0.5 μm on which the TFT element was formed.

The liquid crystal display of this example had good liquid crystal alignment, voltage holding ratio and contrast, and good display quality even after driving for 5000 hours. Also, the resistivity is 10 ⁻¹² Ω
Even when a liquid crystal material containing a relatively large amount of impurity ions of cm was used, no burn-in failure occurred.

In the case of a liquid crystal material having spontaneous polarization such as an antiferroelectric liquid crystal, the relative permittivity of the liquid crystal material is as high as about 150. As a result, the voltage drop at the alignment film portion is large. In this example, the relative dielectric constant of the alignment film was increased from 3.0 to 6.8 by the plasma treatment, so that the driving voltage of the liquid crystal display device could be significantly reduced.

The alignment film of this example was analyzed by XPS using characteristic X-rays of Al. The angles of the detector were set to 5 degrees and 90 degrees, and the element composition ratios of about 20 A and about 100 A were obtained from the surface of the sample, respectively. The average composition ratio of the F element from the sample surface to the depth of 20A is 7%, and the depth from the sample surface is 1
The average composition ratio of the F element up to 00A was 1%.
That is, the halogen element content (composition ratio) in the molecules constituting the film surface is larger than the halogen element content (composition ratio) in the molecules constituting the vicinity of the substrate interface or inside the film.

(Embodiment 4) Referring to FIG.
An example will be described. This embodiment is different from the first embodiment in that liquid crystal molecules are aligned without performing a rubbing process.

As shown in FIG. 9A, the first substrate has the same structure as the substrate 61 described in the first embodiment. First, a gate metal made of an MoTa alloy is provided on the substrate surface by magnetron sputtering. It was formed using a method. Next, a gate insulating film made of a gate oxide film and silicon nitride was formed. An a-Si film and a channel protective film made of silicon nitride were formed thereon by a CVD method.

After forming a-Si islands by etching, an ohmic layer was formed. Thereafter, a pixel electrode was formed, and a source / drain electrode made of Mo / Al was further formed. Thus, the TFT is completed. Finally, a 2500-Å-thick silicon oxide protective layer (passivation film) was formed on the TFT.

A solution prepared by dispersing a red pigment in a photosensitive BCB varnish was applied on a second substrate, and a portion for forming a red color filter was exposed. Thereafter, the non-exposed portions were removed with a developer to form a red color filter. Similarly, blue and green color filters were formed on the second substrate. A transparent electrode of indium tin oxide (ITO) was formed on the entire surface of the substrate on which the color filter was formed. Color filters using photosensitive BCB are excellent in chemical resistance and heat resistance.

On a first substrate having a TFT and a second substrate having a color filter, a soluble polyimide (AL-1051 manufactured by Nippon Taisei Rubber Co., Ltd.) was used as an alignment film 41.
And print it on a hot plate at 80 ° C for 1 minute.
Further, it was baked at 180 ° C. for 30 minutes in an N 2 oven to evaporate the solvent. The thickness of the polyimide was 500 angstroms.

The first and second substrates were placed in a plasma chamber and subjected to the following hydrophobic treatment. FIG. 9B
As shown in FIG. 5, an ion beam containing F ⁺ , F ⁻ , and F ^* (fluorine radical) was irradiated from a beam source 80 for 5 minutes from an oblique direction (θ) of the soil liquid crystal alignment film 41. In the present embodiment, θ is set to 60 degrees, but θ is preferably 10 to 70 degrees. The ion beam is formed of NF ₃ plasma (N
It was obtained by narrowing F ⁺ or F ⁻ generated from F ₃ gas pressure (0.2 Torr) into a beam using an electric field.

Before performing ion beam irradiation (FIG. 9)
(See (a)), the molecular skeleton (polymer main chain) 81 on the surface of the polyimide alignment film 41 has a zigzag structure. When the ion beam is irradiated from an oblique direction, as shown on the right side of FIG. 9B, fluorination occurs selectively in a portion 82 of the molecular chain of the alignment film perpendicular to the irradiation direction of the ion beam.

A portion 83 parallel to the ion beam irradiation direction
Hardly undergoes fluorination. As a result, FIG.
As shown in (C), the pretilt angle of the liquid crystal molecules in (B) is higher than the pretilt angle (the angle between the substrate surface and the main axis of the liquid crystal molecules) in (A). Bulk liquid crystal molecules (C) are affected by the high pretilt angle (B),
It has a pretilt angle in the same direction as (B). In this way, it is possible to obtain the same liquid crystal molecular alignment as that obtained by rubbing in the directions (b) to (b) by ion beam irradiation.

Next, spacer particles of 5 μm in diameter were scattered on the first substrate, and an epoxy-based sealing material mixed with a fiber of 5 μm in diameter was applied to the periphery of the second substrate. The first substrate and the second substrate were opposed. Position the upper and lower substrates accurately, and pressurize the two opposing substrates,
The sealing material 16 was completely cured by heating in an oven at 160 ° C. for 3 hours, and the first substrate and the second substrate were bonded to form a cell. After injecting the chiral nematic liquid crystal material into this cell, the inlet was cured with an epoxy-based adhesive. A drive circuit was mounted thereon to produce a TN liquid crystal display device having a diagonal of 9 inches.

When the pretilt angle of the liquid crystal display device was measured, a uniform pretilt angle of 8.0 degrees ± 0.1 was obtained over the entire surface of the substrate. As a result, the edge reverse was hidden by the black matrix portion, and a contrast of 100: 1 was obtained. This pretilt angle did not change even after a 500-hour driving test under high temperature and high humidity at a temperature of 80 ° C. and a humidity of 90%.

The adhesion between the alignment film and the substrate was good, and the alignment film was not peeled off during rubbing even in the 1.5 μm-height irregularities where the TFT elements were formed.

The liquid crystal display device of this example had good liquid crystal alignment, voltage holding ratio, and contrast, and had good display quality even after driving for 5000 hours. Also, the resistivity is 10 ⁻¹² Ω
Even when a liquid crystal material containing a relatively large amount of impurity ions of cm was used, no burn-in failure occurred.

Further, as in the present embodiment, the uniform alignment of the liquid crystal molecules could be obtained without rubbing by irradiating the ion beam obliquely.

The alignment film of this example was analyzed by XPS using characteristic X-rays of Al. 12 ° and 90 ° detector angles
And from the surface of the sample about 20 A and about 100 A, respectively.
Was determined.

The average composition ratio of the F element from the sample surface to the depth 12A is 2.5%,
The average composition ratio of the F element up to A was 1%. That is, the halogen element content (composition ratio) in the molecules constituting the film surface is larger than the halogen element content (composition ratio) in the molecules constituting the vicinity of the substrate interface or inside the film.

(Embodiment 5) A fifth embodiment of the present invention will be described with reference to FIG. The third embodiment is different from the first embodiment in that a grub-like alignment film is used and liquid crystal molecules are aligned without performing a rubbing process.

First, an active matrix substrate 61 is obtained in the same manner as in the first embodiment. That is, a gate metal made of a MoTa alloy was formed on the first substrate by using a magnetron sputtering method. Next, a gate insulating film made of a gate oxide film and silicon nitride was formed. A-S on it
CVD of i-film and channel protective film made of silicon nitride
Formed by the method.

After an island of a-Si was formed by etching, an ohmic layer was formed. Thereafter, a pixel electrode was formed, and a source / drain electrode made of Mo / Al was further formed. Thus, the TFT is completed. Finally, a silicon oxide protective layer (also called a passivation film) having a thickness of 2500 angstroms was formed on the TFT.

Further, similarly to the second substrate of the first embodiment, a solution prepared by dispersing a red pigment in a photosensitive BCB varnish is applied to the soil of the second substrate to form a red color filter. The exposed part was exposed. Thereafter, the non-exposed portions were removed with a developer to form a red color filter.
Similarly, blue and green color filters were formed on the second substrate. A transparent electrode of indium tin oxide (ITO) was formed on the entire surface of the substrate on which the color filter was formed. A color filter using photosensitive BCB is excellent in chemical resistance and heat resistance.

On a first substrate having a TFT and a second substrate having a color filter, a photosensitive BCB varnish is applied, pre-baked (80 ° C. for 1 minute), and exposed (36
5 m) 250 mJ / cm ² ), development (3 xylene)
Minutes), post-baking (200 ° C, 30 minutes), and convex part 1
A grub-like alignment film 84 having a micron space of 1 micron was formed.

The first and second substrates were placed in a plasma chamber and subjected to the following hydrophobic treatment.

As shown in FIGS. 10 (a), 10 (b) and 10 (c), the oblique direction of the liquid crystal alignment film from the direction along the groove.
From (θ), F ⁺ , F ⁻ , F
^* Irradiated with an ion beam containing (fluorine radical) for 5 minutes. In the present embodiment, θ is set to 30 degrees, but θ is set to 10 degrees.
Preferably it is 70 degrees. The ion beam is C
It was obtained by focusing F ⁺ and F ⁻ generated from F ₄ plasma (CF ₄ gas pressure 0.4 Torr) on a beam using an electric field. According to the same principle as described in the fourth embodiment,
The same liquid crystal molecule alignment as that obtained when rubbing was performed in the directions from (d) to (c) could be obtained by ion beam irradiation.

Next, spacer particles of 5 μm in diameter were scattered on the first substrate, and an epoxy sealing material mixed with a fiber of 5 μm in diameter was applied to the periphery of the second substrate. The first substrate and the second substrate were opposed. Position the upper and lower substrates accurately, and pressurize the two opposing substrates,
The sealing material was completely cured by heating in an oven at 160 ° C. for 3 hours, and the first substrate and the second substrate were bonded to form a cell. After injecting the chiral nematic liquid crystal material into this cell, the inlet was cured with an epoxy-based adhesive. A drive circuit is mounted on this, and a diagonal 9
An inch TN liquid crystal display device was manufactured.

When the pretilt angle of the liquid crystal display device was measured, a uniform pretilt angle of 8.0 degrees ± 0.1 was obtained over the entire surface of the substrate. As a result, the edge reverse was hidden by the black matrix portion, and a contrast of 100: 1 was obtained. This pretilt angle did not change even after a 500-hour driving test under high temperature and high humidity at a temperature of 80 ° C. and a humidity of 90%.

The adhesion between the alignment film and the substrate was good, and the alignment film was not peeled off during rubbing even in the 1.5 μm-height irregularities where the TFT elements were formed.

The liquid crystal display of this example had good liquid crystal alignment, voltage holding ratio, and contrast, and display quality was good even after driving for 5000 hours. Also, the resistivity is 10 ⁻¹² Ω
Even when a liquid crystal material containing a relatively large amount of impurity ions of cm was used, no burn-in failure occurred.

Further, as in the present embodiment, by uniformly irradiating the grub-like alignment film with an ion beam, uniform alignment of liquid crystal molecules could be obtained without rubbing treatment. As the material of the grub alignment film, photosensitive BCB, photosensitive polyimide, and photosensitive acrylic resin are preferable.

(Embodiment 6) A sixth embodiment of the present invention will be described with reference to FIG. The difference from the first embodiment is that a liquid crystal display device having a wide viewing angle is realized by changing the plasma conditions for each region.

First, both the first substrate 61 and the second substrate 66 having the same TFT structure and color filter structure as in the first embodiment were prepared.

On the first substrate 61 having a TFT and the second substrate 66 having a color filter, an alignment film 4 is formed.
Soluble polyimide (AL-1 made by Nippon Taisei Rubber Co., Ltd.)
051) at 80 ° C. using a hot plate.
The mixture was baked at 180 ° C. for 30 minutes in an N ₂ oven for 30 minutes to evaporate the solvent. The thickness of the polyimide was 500 angstroms.

The first and second substrates having the polyimide alignment film formed thereon were rubbed. The rubbing cloth used was made of rayon and had a hair tip diameter of 0.1 to 10 microns. The rubbing conditions were as follows: the number of rotations of the roller was 500 rpm, the substrate moving speed was 50 mm / s, the pushing amount was 0.5 mm, and the number of rubbing was one.

Rubbed first and second substrates 6
Sample Nos. 1 and 66 were placed in a plasma chamber, and the surface of the alignment film was partially hydrophobized. More specifically, a stainless mask 91 having an opening of 40 μm square in a checkered pattern is placed on these substrates, and placed in a chamber evacuated to 10 ⁻⁶ Torr, and NF ₃ gas is introduced. .2
Torr, parallel plate electrode of 900 cm ² electrode, distance between electrodes: 3.5 cm, applied voltage: 13.56 MHz, 1
Plasma treatment was performed at 5 W for 1 minute (FIG. 11B).
As a result, a half area of the pixel corresponding to the mask opening (the signal line 94, the gate line 92, the Cs line 9 on the TFT substrate side)
The area 95 surrounded by 3 is hydrophobicized in a checkered pattern (FIG. 9C).

Next, spacer particles of 5 μm in diameter were sprayed on the first substrate, and an epoxy sealing material mixed with a fiber of 5 μm in diameter was applied to the periphery of the second substrate. The hydrophobic region of the first substrate and the non-hydrophobic region of the second substrate were opposed, and the non-hydrophobic region of the first substrate and the hydrophobic region of the second substrate were opposed to each other. The position of the upper and lower substrates is accurately adjusted, and the two substrates facing each other are placed in an oven while being pressurized, and heated at 160 ° C. for 3 hours to completely cure the sealing material. And the second substrate were bonded to form a cell. After injecting a chiral nematic liquid crystal material (the twist direction of the chiral material is a direction in which liquid crystal molecules are in a splay alignment) into the cell, the inlet was cured with an epoxy-based adhesive. Mount a drive circuit on this,
A TN liquid crystal display device having a diagonal of 9 inches was manufactured.

When the pretilt angle of this liquid crystal display device was measured, it was found that the degree of the pretilt angle was 6.0 degrees ± 0.
1. A uniform pretilt angle of 1.0 degree ± 0.1 was obtained on the non-hydrophobic alignment film. Edge reverse is hidden by the black matrix part, and contrast 10
0: 1 could be obtained. The pretilt angle is 8
There was no change even after a 500-hour driving test at a high temperature and a high humidity of 0 ° C. and a humidity of 90%.

In this embodiment, the hydrophobic region and the non-hydrophobic region (the high pretilt angle region and the low pretilt angle, respectively) face each other, and the rising direction of the liquid crystal molecules when voltage is applied is 18
Two regions differing by 0 degrees were formed. As a result, a cell having a wide viewing angle without gradation inversion could be manufactured by a simple process. The reason why the wide viewing angle is obtained is that these two regions mutually compensate the viewing angle.

The adhesion between the alignment film and the substrate was good, and the alignment film was not peeled off during rubbing even in the 1.5 μm-height irregularities where the TFT elements were formed.

The liquid crystal display of this example had good liquid crystal alignment, voltage holding ratio, and contrast, and had good display quality even after driving for 5000 hours. Also, the resistivity is 10 ⁻¹² Ω
Even when a liquid crystal material containing a relatively large amount of impurity ions of cm was used, no burn-in failure occurred.

In addition, the relative dielectric constant of the alignment film was increased from 3.0 to 3.8 by the plasma treatment of the present example, and the driving voltage of the liquid crystal display device could be reduced.

(Embodiment 7) This embodiment is different from the embodiment 1 in that the pretilt angle of liquid crystal molecules is remarkably increased to realize a high-speed response.

First, both the first substrate and the second substrate having the same TFT structure and color filter structure as in the first embodiment were prepared.

On a first substrate having a TFT and a second substrate having a color filter, BC
B solution (manufactured by Dow Chemical Co., Ltd.) was printed, and was heated at 80 ° C. for 1 minute using a hot plate, and further placed in an N ₂ oven for 20 minutes.
It was baked at 0 ° C. for 30 minutes to polymerize. The thickness of the BCB polymer was 500 Å.

The first and second substrates having the BCB polymer alignment film formed thereon were subjected to a rubbing treatment. The rubbing cloth used was made of rayon and had a hair tip diameter of 0.1 to 10 microns. The rubbing conditions were as follows: the number of rotations of the roller was 500 rpm, the substrate moving speed was 50 mm / s, the pushing amount was 0.5 mm, and the number of rubbing was one.

The rubbed first and second substrates were placed in a plasma chamber, and the surface of the alignment film was subjected to a hydrophobic treatment. Specifically, these substrates are placed in a chamber evacuated to 10 ^-6 Torr, and NF ₃ gas is introduced to 0.2 Torr, a parallel plate electrode of 900 cm ² electrode, the distance between the electrodes: 3.5 cm, Applied voltage: 13.56M
Plasma treatment was performed at 15 Hz for 3 minutes.

Next, spacer particles of 5 μm in diameter were sprayed on the first substrate, and an epoxy sealing material mixed with a fiber of 5 μm in diameter was applied to the periphery of the second substrate. The first substrate and the second substrate were opposed. While accurately aligning the upper and lower substrates, pressurizing the two opposing substrates,
The sealing material was completely cured by heating in an oven at 160 ° C. for 3 hours, and the first substrate and the second substrate were bonded to form a cell. After injecting a chiral nematic liquid crystal material into this cell, the inlet was cured with an epoxy-based adhesive. A drive circuit is mounted on this, and a diagonal 9
An inch TN liquid crystal display device was manufactured.

When the pretilt angle of this liquid crystal display device was measured, a uniform pretilt angle of 40.0 degrees ± 0.1 was obtained over the entire surface of the substrate. As a result, the time required for the liquid crystal molecule arrangement to change from the off state to the on state was 0.5 ms, and the time required for the liquid crystal molecule arrangement to change from the on state to the off state was 0.8 ms, and a high-speed response was realized. Further, the edge reverse was hidden by the black matrix portion, so that a contrast of 200: 1 could be obtained.

This pre-tilt angle is a temperature of 80 ° C. and a humidity of 90
% Did not change even after a 500-hour driving test at high temperature and high humidity.

The adhesion between the alignment film and the substrate was good, and the alignment film did not peel off during rubbing even in the 1.5 μm-height irregularities where the TFT elements were formed.

The liquid crystal display device of this example had good liquid crystal alignment, voltage holding ratio, and contrast, and display quality was good even after driving for 5000 hours. Also, the resistivity is 10 ⁻¹² Ω
Even when a liquid crystal material containing a relatively large amount of impurity ions of cm was used, no burn-in failure occurred.

Further, the relative dielectric constant of the alignment film was increased from 3.0 to 3.8 by the plasma treatment of this example, and the driving voltage of the liquid crystal display device could be reduced.

The alignment film of this example was analyzed by XPS using characteristic X-rays of Al. 12 ° and 90 ° detector angles
And from the surface of the sample about 20 A and about 100 A, respectively.
Was determined. The average composition ratio of the F element from the sample surface to a depth of 20A was 20%, and the average composition ratio of the F element from the sample surface to a depth of 100A was 1.5%. That is, the halogen element content (composition ratio) in the molecules constituting the film surface is larger than the halogen element content (composition ratio) in the molecules constituting the vicinity of the substrate interface or inside the film.

(Embodiment 8) The present embodiment is different from the embodiment 1 in that rubbing is performed after the plasma treatment and the reaction gas of the plasma and the material of the alignment film are changed.

First, both the first substrate and the second substrate having the same TFT structure and color filter structure as in the first embodiment were prepared.

On a first substrate having a TFT and a second substrate having a color filter, BC
B solution (manufactured by Dow Chemical Co., Ltd.) was printed, and the solution was heated at 80 ° C. for 1 minute using a hot plate, and further placed in an N ₂ oven for 25 minutes.
It was baked at 0 ° C. for 30 minutes to polymerize. The thickness of the BCB polymer film was 500 Å.

The first and second substrates were placed in a plasma chamber, and the surface of the alignment film was subjected to a hydrophobic treatment.

More specifically, these substrates are set to 10 ^-6 To
rr was placed in a chamber evacuated to rr, and CCl ₄ gas was introduced to 0.1 Torr, a parallel plate electrode having an electrode of 900 cm ^2, a distance between the electrodes: 3.5 cm, and an applied voltage: 1
Plasma treatment was performed at 3.56 MHz and 10 W for 1 minute.

The plasma-treated first and second substrates were rubbed. The rubbing cloth used was made of rayon and had a hair tip diameter of 0.1 to 10 microns. The rubbing conditions were as follows: roller rotation speed 800 rpm, substrate moving speed 5
The rubbing frequency is 0 mm / s and the pushing amount is 0.6 mm.

Next, spacer particles of 5 μm in diameter were scattered on the first substrate, and an epoxy sealing material mixed with a fiber of 5 μm in diameter was applied to the periphery of the second substrate. The first substrate and the second substrate were opposed. While accurately aligning the upper and lower substrates, pressurizing the two opposing substrates,
The sealing material was completely cured by heating in an oven at 160 ° C. for 3 hours, and the first substrate and the second substrate were bonded to form a cell. After injecting the chiral nematic liquid crystal material into this cell, the inlet was cured with an epoxy-based adhesive. A drive circuit is mounted on this, and a diagonal 9
An inch TN liquid crystal display device was manufactured.

When the pretilt angle of the liquid crystal display device was measured, a uniform pretilt angle of 10.0 degrees ± 0.1 was obtained over the entire surface of the substrate. As a result, the edge reverse was hidden by the black matrix portion, and a contrast of 250: 1 could be obtained. This pretilt angle is 500 ° C under high temperature and high humidity of 80 ° C and 90% humidity.
There was no change even after the time drive test.

The adhesion between the alignment film and the substrate was good, and the alignment film did not peel off during rubbing even in the 1.5 μm-height irregularities where the TFT elements were formed.

The liquid crystal display of this example had good liquid crystal alignment, voltage holding ratio, and contrast, and had good display quality even after driving for 5000 hours. Also, the resistivity is 10 ^-13 Ω
Even when a liquid crystal material containing a relatively large amount of impurity ions of cm was used, no image sticking occurred.

Further, the relative dielectric constant of the alignment film was increased from 2.7 to 3.7 by the plasma treatment of this example, and the driving voltage of the liquid crystal display device could be reduced.

Even in the case of rubbing after the plasma treatment as in the present embodiment, a good liquid crystal display device similar to the first embodiment could be formed.

The alignment film of this example was analyzed by XPS using characteristic X-rays of Al. 12 ° and 90 ° detector angles
And from the surface of the sample about 20 A and about 100 A, respectively.
Was determined.

The average composition ratio of the Cl element from the surface of the sample to a depth of 20 A is 2%, and the depth is 100 A from the surface of the sample.
The average composition ratio of Cl element up to 1% was 1%. That is, the halogen element content (composition ratio) in the molecules constituting the film surface is larger than the halogen element content (composition ratio) in the molecules constituting the vicinity of the substrate interface or inside the film.

In order to exhibit the effect of the present invention, the average composition ratio of Cl element from the surface of the sample to the depth of 20 A is 2% or more (preferably 4% or more and 50% or less). The average composition ratio of Cl element up to 100 A is 2
% (Preferably 1% or less).

These examples are described for the purpose of facilitating the understanding of the present invention, and do not limit the present invention. The present invention can be applied to a liquid crystal display device having a thin film diode element (TFD), a reflection type liquid crystal display device, and a projection type liquid crystal display device. In addition, various modifications can be made without departing from the gist of the present invention.

[0146]

The liquid crystal molecules can be given a high pretilt angle of 10 degrees or more by making the surface region of the liquid crystal alignment film formed on the substrate hydrophobic. An arbitrary pretilt angle can be obtained by changing the irradiation conditions (processing time, power) of the charged or neutral particle flux.

The surface of the alignment film can be selectively hydrophobized by irradiation with a charged or neutral particle bundle. At this time, since the alignment film near the substrate interface is not hydrophobized, the adhesion to the substrate is good.

Irradiation of charged or neutral particle flux has been used in the formation of amorphous silicon for large-scale integrated circuits (LSIs) and liquid crystal display elements, and can uniformly treat large-area substrates. Therefore, a uniform and high pretilt angle can be obtained on a large-area substrate.

Since the alignment film molecules and the halogen atoms are strongly bonded by the irradiation of the charged or neutral particle flux, the (1)
Higher pretilt angle can be stably provided.

Since the composition ratio of the halogen element on the surface of the alignment film hardly changes even if the rubbing conditions are changed, the value of the pretilt angle hardly changes even if the rubbing conditions are changed.

Since the surface of the liquid crystal alignment film is rendered hydrophobic by irradiation with a charged or neutral particle bundle, it becomes difficult for the alignment film to absorb water, and hydrolysis of the alignment film hardly occurs, thereby increasing the long-term reliability of the liquid crystal alignment film. .

Since the surface of the liquid crystal alignment film has been rendered hydrophobic by irradiation with the charged or neutral particle bundle, ionic impurities are less likely to be adsorbed on the alignment film, and defective image sticking can be prevented.

Since the surface of the liquid crystal alignment film is halogenated by irradiation with a charged or neutral particle bundle, the polarizability of the alignment film is increased, and the dielectric constant of the alignment film can be increased.

By irradiating the charged or neutral particle bundle from the oblique direction of the substrate, the liquid crystal molecules can be aligned without rubbing, and the pretilt angle can be controlled.

The irradiation of the charged or neutral particle flux is partially performed, and the region of the first substrate having a high pretilt angle and the region of the second substrate having a low pretilt angle are changed to the region of the second substrate having a high pretilt angle. The liquid crystal display device having a wide viewing angle can be manufactured by facing the region of the first substrate with the low pretilt angle.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a relationship between a plasma processing time and a surface energy.

FIG. 2 is a diagram illustrating a relationship between a plasma processing time and a pretilt angle.

FIG. 3 is a diagram illustrating a relationship between a pretilt angle and a surface energy.

FIGS. 4A and 4B are schematic diagrams illustrating the adhesion between a substrate and an alignment film.

FIG. 5 is a diagram illustrating a relationship between a rubbing condition and a pretilt angle.

FIG. 6 is a diagram showing a relationship between rubbing treatment and deformation of alignment film molecule side chains.

FIG. 7 is a diagram for explaining a liquid crystal display device according to the first embodiment of the present invention.

FIG. 8 is a schematic diagram of a plasma device used in the present embodiment.

9A and 9B are diagrams illustrating a liquid crystal display element according to Example 4 of the present invention, wherein FIG. 9A is a side view of a substrate before particle irradiation and a schematic view showing alignment film molecular chains on the alignment film surface, and FIG. FIG. 2 is a schematic view showing a side view of a substrate and a molecular chain of an alignment film on a surface of an alignment film in a state of particle irradiation, and FIG.

10A and 10B are diagrams illustrating a liquid crystal display element according to a fifth embodiment of the present invention, wherein FIG. 10A is a perspective view, FIG. 10B is a front view, and FIG.
Is a side view.

11 (a), (b), and (c) show Example 6 of the present invention.
FIGS. 3A and 3B are diagrams illustrating a liquid crystal display device according to the first embodiment, in which FIG. 3A is a plan view of a mask, FIG.

[Explanation of symbols]

 41: alignment film, 62: TFT, 63: pixel electrode, 64: protective film, 65: spacer, 66: second substrate, 66: counter electrode, 67: sealing material, 68: liquid crystal material, 70: plasma chamber, 80 ... beam source,

Claims (6)

[Claims] In a liquid crystal alignment film formed on a substrate, the halogen element content (composition ratio) in molecules constituting the film surface is determined by the halogen element content in molecules constituting the vicinity of the substrate interface or inside the film. (Liquid composition ratio). 2. An alignment film formed on a substrate, wherein a halogen element content in molecules constituting the film surface is 2% or more, and a halogen element content in molecules constituting the vicinity of the substrate interface is 2%. Liquid crystal alignment film, wherein 3. The liquid crystal alignment film according to claim 1, wherein the halogen element is fluorine. 4. A method for producing a liquid crystal alignment film, characterized by imparting a high pretilt angle to liquid crystal molecules by irradiating the surface of the liquid crystal alignment film with a charged particle or a neutral particle bundle containing a halogen element as a constituent element. . 5. The method for producing a liquid crystal alignment film according to claim ₄ , wherein NF ₃ or CF ₄ is used as a gas source for said charged particle or neutral particle bundle. 6. The method for producing a liquid crystal alignment film according to claim 4, wherein the irradiation of the charged particles or the neutral particle bundle is performed on the rubbed surface of the liquid crystal alignment film.