JP2000122064A - Alignning treatment of liquid crystal alignment film and its device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for giving an alignment characteristic without contacting, without leaving ions in an alignment film and without bringing a chemical change in an alignment film molecules, and to provide simultaneously a contamination-free liq. crystal cell having excellent electric property. SOLUTION: A substrate 13 on which an alignment film is formed is fixed to a substrate holder 16. The holder 16 can be rotated around an axis 14 and shifted in directions X-Y. Aligning treatment is carried out by irradiating the substrate with a neutral atomic beam emitted from a high-energy atomic gun 11. The polar angle of incidence θ can be varied by moving the atomic gun 11 along a moving locus 15 and a tilt angle can be varied in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for aligning a liquid crystal alignment film, and more particularly to a method and an apparatus for aligning liquid crystal without contact.

[0002]

2. Description of the Related Art Operation modes of a liquid crystal panel include a twisted nematic (TN) mode, a super twisted nematic (STN) mode, and an in-plane mode.
A switching (IPS) method and the like are known,
Also, ferroelectric liquid crystal panels have been developed, no matter which method is used or which material is selected,
In order to determine the initial alignment state of the liquid crystal, it is necessary to regulate the direction of the molecular axis of the liquid crystal on the substrate surface, and an alignment film is used for that purpose. As a means for obtaining the initial alignment used industrially, a rubbing treatment of rubbing the surface of a polymer thin film made of polyimide or the like with a cloth-wound roller is mainstream, whereby liquid crystal alignment in the rubbing direction can be obtained.
This rubbing treatment is widely used because of its simplicity and low cost, but it has a problem of contamination of the liquid crystal alignment film surface and static electricity.

One of the new methods for solving the above-mentioned problem is an alignment treatment method by ion beam irradiation. This is a single element ion beam emitted from an ion gun such as argon, which is usually used for surface analysis methods such as secondary ion mass spectrometry, to form minute grooves on the alignment film surface or decompose molecules on the alignment film surface Thus, the surface of the alignment film is treated so as to obtain the initial alignment of the liquid crystal molecules.

[0004]

In the rubbing method which is currently mainstream, contamination and static electricity due to rubbing are problematic as described above. In the ion beam irradiation method proposed to solve this problem, positive ions (eg, argon ions) of an inert gas are irradiated on the surface of the alignment film, so that the alignment film is positively charged. As a method of removing the charge, it is general to irradiate the surface of the alignment film with electrons simultaneously with the irradiation of ions. However, when an alignment film is formed by this method to form a liquid crystal cell, an electric field is often generated inside the cell, which deteriorates the electric characteristics of the liquid crystal cell. The fact that an internal electric field is generated after the cell is formed means that ions remain in the alignment film.

[0005] Irradiation of positive ions not only causes a sputtering phenomenon but also chemically causes a reaction between ions and molecules. Positive ions of the inert gas deprive the alignment film molecules of electrons with a strong electron acceptor, and this serves as a starting point to induce a decomposition reaction of the alignment film molecules. The reaction is very complex and the generated ions are very diverse, as they are further affected by ions during the decomposition process. Since the decomposition by sputtering overlaps with this, a very large variety of molecular ions are generated in the alignment film. This is considered sufficiently because complicated molecular ions are detected in the mass spectrum of the polymer thin film by the secondary ion mass spectrometry using the same ion gun. These ions are generated not only on the surface of the alignment film but also inside the alignment film. In the orientation treatment by the ion beam method, ions accelerated at several kV are irradiated. However, ions having such high energy penetrate into the interior of the orientation film and cause a complicated reaction as described above, thereby causing many ions. Generate.

[0006] The polarity of ions generated by ion beam irradiation is both positive and negative, but many are positive in view of the law of conservation of charge. Although electron irradiation is performed to neutralize the positive ions, the ions are not actually neutralized. Macroscopically, it merely neutralizes the entire alignment film. Many cations derived from organic compounds do not take a stable chemical structure even when donated with electrons, and conversely, protons are extracted from the surroundings, donated, or decomposed to generate ions. Therefore, ions eventually remain in the alignment film, and the electrical characteristics of the liquid crystal cell deteriorate.

An object of the present invention is to solve the above-mentioned problems of the prior art, and an object of the present invention is to eliminate non-contact without leaving ions in the alignment film and without causing a chemical change in alignment film molecules. It is an object of the present invention to provide a method capable of imparting alignment characteristics by using a liquid crystal cell having no contamination and having excellent electric characteristics.

[0008]

According to the present invention, there is provided, according to the present invention, a method of scanning a substrate with a high-speed, electrically neutral, chemically inert beam of atoms. There is provided an alignment treatment method for a liquid crystal alignment film, characterized by selectively aligning the entire liquid crystal alignment film formed on a substrate or a portion thereof.

According to the present invention, in order to achieve the above object, a substrate holder for holding a substrate on which an alignment film is formed is provided in a vacuum chamber, and the substrate holder is electrically mounted on the substrate held by the substrate holder. And an atom gun for irradiating a high-speed beam of neutral and chemically inactive atoms to the liquid crystal alignment film alignment processing apparatus.

[0010]

When a neutral atom that is electrically neutral and chemically inactive collides with an alignment film molecule at high speed, the detailed mechanism is not clear, but the alignment film molecule aligns in parallel with the incident direction of the atom beam. , The same anisotropy as rubbing is induced,
When a liquid crystal cell is manufactured using the processed substrate, a uniform liquid crystal alignment can be obtained. Also, changing the incident angle of the neutral atom beam on the substrate changes the pretilt angle of the liquid crystal. The results of these experiments will be described in detail in Examples, but the alignment treatment using a high-speed atom gun can obtain a liquid crystal alignment film in the same way as rubbing, and also controls the pretilt angle control of liquid crystal, which has been highly material-dependent. It can be performed only under conditions.

In addition, when ions collide with molecules of the alignment film, a complicated chemical reaction due to charge transfer proceeds, and various types of ions remain in the alignment film, thereby increasing the electrical characteristics of the liquid crystal device. According to the present invention in which neutral and inactive atoms such as argon and xenon collide with each other, the present invention can maintain stable electrical characteristics without residual ions. In addition, since the treatment method of the present invention does not involve a chemical change such as decomposition of alignment film molecules, it is possible to prevent occurrence of contamination and to obtain an alignment film having high stability.

[0012]

Next, an embodiment of the present invention will be described in detail with reference to FIGS. 1 to 4
1 is a schematic configuration diagram showing an apparatus in which a processing method of the present invention is performed. As shown in FIG. 1, a glass substrate 13 coated with an alignment film is fixed to a substrate holder 16 provided in a vacuum chamber 17. When neutral atoms emitted from the high-speed atom gun 11 collide with molecules on the alignment film surface, the detailed mechanism is unknown, but the long axis of the alignment film molecules is
Rearrange in parallel with The fast atom ion gun may be one used for general fast atom bombardment mass spectrometry.

The high-speed atomic gun 11 is fixed to an arm (not shown) so as to be movable along a movable locus 15, and the substrate holder 16 is movable on a plane, that is, in the XY directions, and is rotated by the holder. The stage is rotatable around the axis 14. The vacuum chamber 17 is further provided with a rare gas gun 18 so that a rare gas can be blown near the irradiation position of the atomic beam 12. The gas of the rare gas gun 18 is supplied by a gas supply pipe 18a, and the gas in the vacuum chamber 17 is exhausted by an exhaust pipe 17a. By changing the two incident directions of the atomic beam 12 to the glass substrate 13, the polar angle θ and the azimuth ψ (see FIG. 2), the orientation of the alignment film molecules can be controlled.
The polar angle θ is set by moving the fast atom gun 11 along the movable trajectory 15, and the azimuthal angle ψ 21 is set by the substrate holder 16.
Can be set to a desired value by rotating the shaft around the holder rotating shaft 14.

As shown in FIG. 3, the polar angle θ can be changed by rotating the arm 31 to which the high-speed atom gun 11 is fixed about the rotation axis 32. The change in the polar angle θ mainly affects the size of the unevenness on the surface of the alignment film, and also simultaneously affects the alignment characteristics of the alignment film formed on the surface of the alignment film (see the third embodiment and FIG. See FIG. 16). Azimuth ψ
The angle between the long axis of the alignment film molecule and the long axis of the substrate can be controlled by changing the angle. Therefore, the orientation film structure can be freely controlled by changing the azimuth angle ψ and the polar angle θ.

The substrate holder 16 for fixing the substrate is shown in FIG.
As shown in (1), it is possible to move in the horizontal plane, that is, in the X direction and the Y direction perpendicular thereto. As a result, the atomic beam can be scanned over the entire substrate surface, and orientation processing on the entire substrate surface can be performed. A heater is embedded in the substrate holder 16 so that a high-speed atomic beam can be irradiated while heating the substrate. Instead of the heater, the substrate surface may be irradiated with infrared light by an infrared lamp.

FIG. 4 shows a specific example of the structure of the high-speed atom gun 11. As shown in FIG. Rare gas atoms such as argon and xenon are supplied to the ionization chamber 41 by a gas supply pipe 41a, and thermions emitted from the filament 42 in the ionization chamber 41 collide with an inert gas in the ionization chamber to form positive ions. As primary ions. The generated primary ions are accelerated by the potential difference between the anode 43 and the ion extraction electrode 44, extracted from the ionization chamber 41, and
The primary ion beam 48 is narrowed down to form a primary ion beam 48. The primary ion beam 48 is adjusted in position by the reflector 46 and enters the gas chamber 47. The same kind of rare gas atoms are supplied to the gas chamber 47 by a gas supply pipe 47a, and the primary ion beam 48 incident on the gas chamber collides with the rare gas atoms at high speed. At this time, charge transfer occurs, and some of the primary ions become fast neutral and inactive atoms, and the fast neutral atom beam 49
Is released as The remaining ions cannot leave the gas chamber 47 to which a negative potential has been applied.

FIG. 5 schematically shows the collision of the neutral atom beam on the alignment film surface. The fast neutral atoms 51 collide with the alignment film 54 and are scattered inside the surface or near the very surface, and some remain as neutral atoms 52 from the alignment film and remain as neutral atoms 53 inside the alignment film. . It is considered that the provision of kinetic energy due to the collision serves as a driving force for rearrangement of the alignment film molecules. Kinetic energy given to the alignment film molecules depends on the incident angle (polar angle θ) of the neutral atom beam, the acceleration voltage of the primary ion beam, and the mass of the neutral atoms. Can be. Also, neutral atoms 53 will remain in the alignment film,
Since it has no charge, it has no effect on electrical characteristics. Further, since the colliding neutral atoms are chemically inactive, the alignment film does not undergo a chemical change. Neutral atoms for irradiation are preferably relatively heavy rare gas atoms such as argon and xenon, and primary ion acceleration is several hundred volts or more.
Several thousand volts is desirable. At this time, when the substrate is heated, the molecules of the alignment film are easily moved depending on the material of the alignment film, and are easily affected by the irradiation of the atomic beam. The heating temperature of the substrate varies depending on the material of the alignment film, but it is preferable that the heating temperature is about the softening point of the material of the alignment film.

When a neutral gas beam is irradiated while irradiating the sample surface with a rare gas with the rare gas gun 18 shown in FIG.
As shown in FIG. 6, neutral atoms 62 irradiated with a rare gas gun
Collision between the atom and the fast neutral atom 61 of the atomic beam occurs. The kinetic energy of the colliding neutral atoms 62 is lower than that of the fast neutral atoms 61 of the atomic beam, and the translation direction also has a distribution. Therefore, this mode is effective when the surface of the alignment film 63 is to be softened. . Here, the influence on the alignment film can be controlled by changing the amount of the rare gas supplied by the rare gas gun.

[0019]

Next, embodiments of the present invention will be described in detail with reference to the drawings. First Embodiment As a first embodiment, the azimuth angle ψ is fixed in the major axis direction of the substrate, the incident angle (polar angle θ) of the xenon beam is set to 60 °, the surface of the polyimide alignment film is treated, and the reflected light is reflected. Analysis of alignment film structure by polarization anisotropy measurement, observation by polarization microscope after cell assembly, measurement of voltage holding ratio, residual D
C evaluation was performed, and the present invention was compared with the case of the rubbing treatment and the case of the ion beam method.

As shown in FIG. 7, 5 cm × 4
A 2 cm × 2 cm ITO (indium tin oxide) film 71 is provided as a transparent electrode in the center of a centimeter glass substrate 72, and a polyamic acid is spin-coated thereon, and is heated at 90 ° C. using an oven. 3
After calcination was performed for 0 minutes, main calcination was performed at 250 ° C. for 1 hour to form a polyimide thin film. Two substrates with the above-mentioned alignment film were prepared for cell assembly. In addition, a substrate without a transparent electrode was also manufactured in order to measure a pretilt angle of a liquid crystal by a crystal rotation method. The thickness of the alignment film measured by a reflection ellipsometer was 810 angstroms to 830 angstroms. In addition, Corning 7059 was used for the glass substrate, and poly (4,4'-oxydiphenylene pyromellitic acid) was used for the polyamic acid.

The glass substrate on which the polyimide thin film was formed was set on the substrate holder 16 such that the long side of the substrate was in the X direction. Azimuth angle of incidence of the fast atom beam at this position ψ
Is set to 0 °. Xenon was used for the fast atoms, and the atomic beam irradiation was performed in a vacuum at an acceleration voltage of the primary ions of 3000 V and a current value of 10 mA. The atomic beam has no charge and cannot be scanned by a deflector or the like. Then, the substrate was moved in the X and Y directions to scan the entire surface of the substrate with an atomic beam. FIG. 8 shows a schematic diagram of the atomic beam scanning. The substrate holder is moved so that the edge of the substrate can be scanned, and the substrate holder is moved in the X direction while irradiating the atomic beam.
The second scan is performed (FIG. 8A). Next, the substrate holder is returned to the original position after the irradiation of the atomic beam is stopped (FIG. 8).
(B)]. Since the beam diameter of the atomic beam is about 2 millimeters, the substrate holder is shifted by 1 millimeter in the Y direction (FIG. 8C), and the substrate holder is moved again in the X direction to scan the atomic beam (FIG. 8). (D)]. Hereinafter, the alignment process was performed on the entire surface of the substrate by repeating the operations of FIGS. 8B to 8D. This time, the moving speed of the substrate in the X direction was 5 mm per second.

Comparative Example 1 As in the case of the first embodiment, as shown in FIG. 7, a 2 cm × 2 cm ITO film is provided at the center of a 5 cm × 4 cm glass substrate. Then, a polyimide film was formed thereon. A substrate without a transparent electrode was also manufactured to measure the pretilt angle of the liquid crystal by the crystal rotation method. The film thickness measured with a reflection ellipsometer is 82
It was between 0 Angstroms and 830 Angstroms. Rubbing is performed using a rayon roll at a rotation speed of 800.
The operation was performed once under the conditions of rotation / minute, indentation of 0.6 mm, and stage speed of 20 mm / sec.

Comparative Example 2 As in the case of the first embodiment, as shown in FIG. 7, a 2 cm × 2 cm ITO film is provided at the center of a 5 cm × 4 cm glass substrate. Then, a polyimide film was formed thereon. A substrate without a transparent electrode was also manufactured to measure the pretilt angle of the liquid crystal by the crystal rotation method. The film thickness measured with a reflection ellipsometer is 81
It was 0 to 820 angstroms. The treatment was performed by an ion beam method using an argon ion gun. The acceleration voltage of the ion beam was 300 volts, the current value was 60 microamperes, and the incident polar angle θ was 60 ° as in the first embodiment.

[Evaluation] In order to evaluate the anisotropy of the alignment films formed according to the first embodiment and the comparative examples 1 and 2, the reflected light polarization anisotropy was measured [Reference: Japanese Journal of Applied Physics 35]. (1996)
5873]. FIG. 9 shows the result. The vertical axis represents the phase difference Δ between the p-polarized component (normal to the substrate) and the s-polarized component (horizontal direction of the substrate) of the reflected light, and the horizontal axis represents the incident azimuth of light in the reflected light polarization anisotropy measurement. The black circles are those subjected to the alignment treatment according to the present invention, and the white squares are those rubbed. The magnitude of the anisotropy is based on the difference DΔ between the maximum value and the minimum value of Δ according to the reference. D.DELTA. Of the rubbed sample was about 5.2.degree., And that of the sample obtained by irradiation with the high-speed atomic beam of the example was about 4.5.degree., Indicating that the same anisotropy as that of the rubbing treatment was developed. . In the case of Comparative Example 2, the angle was 4.7 °. According to the reference document, the thickness of the alignment layer and the tilt angle of the alignment layer (the tilt angle of the optically anisotropic axis: substrate: Table 1 shows the inclination angle with respect to the surface.

[0025]

[Table 1]

In order to compare the cells of the alignment film formed by each method, an anti-parallel cell (a cell in which the orientation directions of two opposing surfaces are different by 180 °) was prepared using these substrates, and a fluorine-based cell was prepared. A liquid crystal cell was fabricated by injecting a nematic liquid crystal material. Only the rubbed surface was cleaned with ultrapure water before the cell assembly. Sealing was performed by heat-treating a thermosetting epoxy adhesive at 150 ° C. for 1 hour. The cell gap was 5 micrometers.
The liquid crystal injection port was sealed with a UV curable resin using a 1 milliwatt low-pressure mercury lamp.

As a result of observation by a polarizing microscope, it was found that all the cells had good liquid crystal alignment. The pretilt angle of the liquid crystal measured by the crystal rotation method was 1.1 ° for those subjected to high-speed atomic beam irradiation, 2.7 ° for rubbing treatment, and 1.9 ° for ion beam treatment. Next, the evaluation results of the electrical characteristics are shown. As electric characteristics, attention was paid to voltage holding ratio and residual DC. The voltage holding ratio was evaluated by applying a rectangular pulse voltage having ± 5.0 volts, a pulse width of 60 microseconds, and a pulse interval of 16.67 milliseconds, and measuring the voltage immediately before the end of the pulse pause period. Table 2 shows the measurement results.

[0028]

[Table 2]

Those subjected to the high-speed atomic beam treatment showed higher values than those subjected to the rubbing treatment, and those subjected to the ion beam treatment exhibited extremely lower values than the others.
This indicates that the liquid crystal subjected to the ion beam treatment contains a large amount of mobile ions. Therefore, the mobile ion density and the mobility in each liquid crystal cell were estimated from the response current waveform to the application of the triangular wave. The applied voltage is a triangular wave voltage of ± 10 volts and a frequency of 0.01 hertz. Table 3 shows the measurement results. It is considered that the reason why the ion density is higher in the rubbing method than in the first embodiment is due to the influence of static electricity generated by friction. The ion beam method has an extremely high ion density as compared with the other methods. Then, it is considered that the reason why the mobility of the ions is low is that the ion diameter is large as compared with those by other methods.

[0030]

[Table 3]

Next, the residual DC of each cell was evaluated.
After applying a DC voltage to the cell for a certain period of time as an initial stress, the applied voltage waveform was switched to an AC rectangular wave voltage, and the residual DC immediately after the switching was measured by the flicker elimination method. From this measurement, the relationship between the magnitude of the residual DC and the initial DC voltage application time was determined for each cell. FIG. 10 shows the device configuration. The cell 104 is divided into a polarizer 102 and an analyzer 103.
The photodiode detector 105 detects the amount of transmitted light from the halogen lamp 101, and data is taken into the personal computer 108 via the oscilloscope 107. At this time, the polarizer 102 and the analyzer 103 were arranged in crossed Nicols. An arbitrary waveform generator 106 was used for voltage application. As shown in FIG. 11, first, a 5 volt DC voltage is applied as an initial DC stress for 0 to 30 minutes.
In order to perform the flicker elimination method, ±
2.5 volts and 10 Hz were applied. The offset value applied to the applied signal when the flicker disappeared was defined as residual DC. FIG. 12 shows the measurement results. Initial DC stress 30
The residual DC of each cell after one minute is about 0.42 volt which is the worst when the alignment treatment is performed by the ion beam method, is about 0.1 volt after the rubbing method, and about 0.03 volt according to the embodiment. And it was the best. As described above, when the alignment treatment method according to the present invention is used, a favorable liquid crystal alignment can be obtained without deteriorating the electrical characteristics.

[Second Embodiment] As a second embodiment, a xenon beam is fixed at an incident angle of 60 ° and a mask is used to irradiate a beam so that the azimuth angles differ by 90 ° within one substrate. After the cell was assembled, observation with a polarizing microscope was performed to confirm that the alignment directions of the liquid crystal were different. As in the first embodiment, as shown in FIG.
After a 2 cm × 2 cm ITO film 71 is provided at the center of a 4 cm glass substrate 72, polyamic acid is spin-coated on the ITO film 71, and baked at 90 ° C. for 30 minutes using an oven. 1 at 250 ° C
This was baked for a time to obtain a polyimide thin film. Two substrates with the above-mentioned alignment film were prepared for cell assembly. The film thicknesses measured with a reflection ellipsometer were 805 angstroms and 810 angstroms, respectively. Corning 7059 was used for the glass substrate, and poly (4,4'-oxydiphenylenepyromellitic acid) was used for the polyamic acid.

The atomic beam irradiation was performed in a vacuum at an acceleration voltage of primary ions of 3000 V and a current value of 10 mA. In order to obtain anti-parallel liquid crystal alignment different by 90 ° in two regions as shown in FIG. 14, half of the substrate was masked and the processing shown in FIG. 13 was performed. First, half of the lower substrate was masked, the substrate holder was rotated by + 45 °, and irradiation was performed in the same manner as in the first embodiment with the incident azimuth of the high-speed ion beam set to 45 ° [(a), (b)] ]. Next, a mask is applied to the half that has been processed by removing the mask, and the substrate is removed by -4.
Rotate to the position of 5 ° to change the incident azimuth of the atomic beam
The same processing was performed at 5 ° [(c), (d)]. The upper substrate was similarly treated at azimuth angles of -135 ° and 135 ° to form an alignment film, and the two substrates were overlapped to inject a fluorine-based nematic liquid crystal material to produce a liquid crystal cell.
The above-described alignment processing can be performed by controlling the XY stage. That is, by turning on / off the high-speed atom gun and moving the substrate in a horizontal plane, it is possible to perform an orientation process at a desired position on the substrate at a desired azimuth. Therefore, the present invention can be applied to the orientation division technique. As a result of observation by a polarizing microscope, it was confirmed that good liquid crystal light distribution was confirmed in each region and that the directions of the liquid crystal directors were different by 90 °.

[Third Embodiment] As a third embodiment, the azimuth angle ψ is fixed in the longitudinal direction of the substrate (ψ = 0 °), and the incident angle (polar angle θ) of the neutral atom beam is 0 to 80. The surface of the alignment film is processed by changing the angle by 10 ° every 10 °, the structure of the alignment film is measured by reflected light polarization anisotropy and the atomic force microscope, the surface roughness is evaluated, and the liquid crystal alignment after the cell is assembled is measured by the polarizing microscope. Observation, pretilt measurement, and residual DC evaluation were performed. As in the first embodiment, as shown in FIG. 7, an ITO film was formed on a glass substrate, and a polyimide film was formed thereon.
In order to assemble the cells, a total of 18 substrates with an alignment film were prepared, two at each polar angle. In addition, a substrate without a transparent electrode film was also manufactured to measure the pretilt angle. The thickness of the alignment film of each substrate measured by a reflection ellipsometer was 805 to 835 angstroms. Corning 7059 was used for the glass substrate, and the polyimide film was formed using poly (4,4'-oxydiphenylene pyromellitic acid). Xenon was used for the fast atoms, the primary ion acceleration voltage was 3000 V, the current value was 10 mA, and the atomic beam was irradiated in vacuum with the polar angle changed as described above.

[Evaluation] FIG. 15 shows the dependency of the orientation layer thickness and the orientation tilt angle on the substrate surface on the incident angle of the high-speed atomic beam by the reflected light polarization anisotropy measurement. As the incident angle was increased, the thickness of the alignment layer and the tilt angle of the alignment were reduced. Further, as shown in FIG. 16, the surface roughness decreased as the incident angle was increased. A liquid crystal cell was fabricated using the substrate having these alignment films, and the pretilt was measured by a crystal rotation method. As shown in FIG. 17, as the incident angle was increased, the pretilt angle was increased up to around 40 ° and then decreased. When observed by a polarizing microscope, many liquid crystal domains were observed when the incident polar angle of the fast atom beam was 0 ° and 10 °, and when the incident polar angle was 20 °, the direction of the liquid crystal director was different in some places. Was observed. At 30 ° or more, uniform liquid crystal alignment was obtained.

Next, the voltage holding ratio and the residual DC were evaluated as electric characteristics of each cell manufactured by changing the incident polar angle of the high-speed atomic beam. Voltage holding ratio ± 5.0 volts, pulse width 60 microseconds, pulse interval 16.67
This was performed by applying a rectangular pulse voltage of millisecond. Table 4 shows the measurement results.

[0037]

[Table 4]

The residual DC of each cell was evaluated by applying a DC voltage as an initial stress to the cell for 30 minutes, switching the applied voltage waveform to an AC rectangular wave voltage, and measuring the residual DC immediately after the switching by a flicker elimination method. did. As shown in FIG. 11, the applied waveform is as follows. First, a DC voltage of 5 volts is applied for 30 minutes as an initial DC stress, and ± 2.5 volts corresponding to a halftone voltage for performing the flicker elimination method is used.
Hz was applied. The offset value applied to the applied signal when the flicker disappeared was defined as residual DC. Table 5 shows the residual DC value of each cell. From the evaluation results shown in Tables 4 and 5, it was found that the values of the voltage holding ratio and the residual DC were good and there was no problem.

[0039]

[Table 5]

As described above, according to the present invention, the pretilt angle of the liquid crystal can be controlled by changing the incident polar angle of the fast atom beam without affecting the electrical characteristics.

[Fourth Embodiment] In the region where the incident polar angle is low in the third embodiment, the alignment of the liquid crystal becomes non-uniform. Therefore, xenon leaks into the vacuum chamber to reduce the pressure to 0.1.
A xenon beam was irradiated at 01 Pascal to perform a softer and more uniform orientation treatment. Alignment film structure analysis by reflected light polarization anisotropy measurement of alignment film subjected to such treatment, observation of alignment film surface morphology by atomic force microscope, polarization microscope observation after cell assembly, measurement of pretilt Was done.

As shown in FIG.
A polyamic acid was spin-coated on a glass substrate measuring 4 cm × 4 cm, and 90 ° C. was performed using an oven.
After calcination at 30 ° C. for 30 minutes, main baking was performed at 250 ° C. for 1 hour to obtain a polyimide thin film. No transparent electrode was formed because no electrical properties were evaluated. The thickness of the alignment film measured by a reflection ellipsometer was 810 Å and 825 Å. Corning 7059 was used for the glass substrate, and poly (4,4) was used for the polyamic acid.
4'-oxydiphenylene pyromellitic acid) was used.

The incident polar angle θ of the high-speed atom beam was set to 20 ° at which non-uniform liquid crystal alignment was obtained in the third embodiment. Xenon was used for the high-speed atomic beam, and the atomic beam was irradiated at an acceleration voltage of the primary ions of 5000 V and a current value of 10 mA. The substrate movement speed was 5 millimeters per second. The distance between the high-speed atom gun and the substrate was 1 cm. An anti-parallel cell was formed with a fluorine-based nematic liquid crystal interposed between the substrates obtained by this alignment treatment, and observed by a polarizing microscope. As a result, unlike the third embodiment, a good liquid crystal alignment was obtained. Table 6 summarizes the thickness of the alignment layer of the alignment film obtained by the reflected light polarization anisotropy measurement, the alignment tilt angle, the pretilt angle measured by the crystal rotation method, and the average unevenness measured by the atomic force microscope.

[0044]

[Table 6]

As described above, in the present invention, a uniform liquid crystal cell having a high pretilt angle can be obtained by lowering the incident polar angle of the fast atom beam and leaking a small amount of xenon into the vacuum chamber.

[0046]

As described above, the method for treating a liquid crystal alignment film of the present invention irradiates a high-speed beam of electrically neutral and chemically inactive atoms onto the alignment film. The following effects can be enjoyed. Since no ions remain in the alignment film, good liquid crystal alignment can be realized without deterioration of electrical characteristics. The pretilt angle of the liquid crystal can be controlled by changing the incident polar angle of the fast atom beam. Since no chemical change is caused in the alignment film, the alignment film can be formed stably and contamination can be prevented. By turning the beam on and off by scanning the substrate, it is possible to easily perform the split orientation process.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a processing apparatus for describing an embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating an outline of an alignment treatment method of the present invention.

FIG. 3 is a partial explanatory view of the processing apparatus of the present invention.

FIG. 4 is a schematic diagram illustrating a configuration of a high-speed atom gun used in the present invention.

FIG. 5 is an operation explanatory diagram illustrating an embodiment of the present invention.

FIG. 6 is an operation explanatory diagram illustrating an embodiment of the present invention.

FIG. 7 is a schematic view of a substrate used in an example of the present invention.

FIG. 8 is a schematic diagram illustrating an alignment treatment method according to the first embodiment of the present invention.

FIG. 9 is a characteristic diagram showing evaluation of the first example of the present invention.

FIG. 10 is an explanatory diagram of a residual DC evaluation measurement method performed on an example of the present invention.

FIG. 11 is a diagram showing applied waveforms used for residual DC evaluation performed in an example of the present invention.

FIG. 12 is a diagram showing a result of a residual DC measurement performed on the first example of the present invention.

FIG. 13 is a view for explaining an alignment treatment method performed in a second embodiment of the present invention.

FIG. 14 is a diagram illustrating an alignment process performed in a second embodiment of the present invention.

FIG. 15 is a diagram showing the incident polar angle dependence of the orientation layer thickness and the orientation tilt angle in the third embodiment of the present invention.

FIG. 16 is a view showing the incident polar angle dependence of the surface unevenness of the alignment film according to the third embodiment of the present invention.

FIG. 17 is a diagram showing the incident polar angle dependence of the pretilt angle of the liquid crystal in the third embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 11 high-speed atom gun 12 atom beam 13 glass substrate 14 holder rotation axis 15 movable trajectory 16 substrate holder 17 vacuum chamber 17a exhaust pipe 18 rare gas gun 18a gas supply pipe 31 arm 32 rotation axis 41 ionization chamber 41a gas supply pipe 42 filament 43 anode 44 Ion extraction electrode 45 Focus electrode 46 Reflector 47 Gas chamber 47a Gas supply tube 48 Primary ion beam 49 Fast neutral atom beam 51 Fast neutral atom 52, 53 Neutral atom 54 Alignment film 61 Fast neutral atom 62 Neutral atom 63 Alignment film 71 ITO film 72 Glass substrate 101 Halogen lamp 102 Polarizer 103 Analyzer 104 Cell 105 Photodiode detector 106 Arbitrary waveform generator 107 Oscilloscope 108 Personal computer

[Procedure amendment]

[Submission date] October 15, 1998 (1998.10.
15)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0037

[Correction method] Change

[Correction contents]

[0037]

[Table 4]

Claims (12)

[Claims] 1. A high-speed, electrically neutral and chemically inactive beam of atoms is scanned over a substrate to select the entire liquid crystal alignment film or a portion thereof formed on the substrate. An alignment treatment method for a liquid crystal alignment film, which comprises: 2. The alignment treatment of a liquid crystal alignment film according to claim 1, wherein a pretilt angle of the liquid crystal is controlled by changing an incident angle (polar angle) of the beam of atoms to the liquid crystal alignment film. Method. 3. The method according to claim 1, wherein the alignment is performed in a vacuum or in an inert gas. 4. The method for aligning a liquid crystal alignment film according to claim 1, wherein the alignment processing is performed while heating the liquid crystal alignment film. 5. The method according to claim 1, wherein the beam of atoms is a beam of inert gas atoms. 6. A substrate holder for holding a substrate on which an alignment film is formed in a vacuum chamber, and a high level of electrically neutral and chemically inactive atoms on the substrate held by the substrate holder. An alignment treatment apparatus for a liquid crystal alignment film, comprising: an atom gun for irradiating a velocity beam. 7. The liquid crystal alignment according to claim 6, wherein the atom gun is fixed to a rotatable arm so that an incident angle (polar angle) of an atom beam on a substrate surface can be changed. Film alignment equipment. 8. The alignment treatment of a liquid crystal alignment film according to claim 6, wherein the substrate holder is movable in X and Y directions and is rotatable around an axis perpendicular to the substrate surface. apparatus. 9. The atom gun has an ionization chamber for ionizing neutral atoms, and a gas chamber for emitting ions emitted from the ionization chamber to emit neutral atoms. Item 7. An alignment treatment apparatus for a liquid crystal alignment film according to Item 6. 10. The liquid crystal according to claim 6, wherein a rare gas gun capable of irradiating a rare gas near a neutral atom irradiation position on the substrate surface is provided in the vacuum chamber. Alignment processing device for alignment film. 11. The apparatus according to claim 6, wherein a heater is built in the substrate holder. 12. The alignment processing apparatus for a liquid crystal alignment film according to claim 6, wherein an infrared lamp capable of irradiating the substrate with infrared light is provided in the vacuum chamber.