JP2002066469A - Method for washing liquid crystal device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To certainly wash a liquid crystal device in a small installation space without damaging an element. SOLUTION: A substrate is attached to a substrate chuck in a step S21. Then, the substrate is rotated (step S22) and, after the substrate is preliminarily wetted (step S23), high pressure pure water is blown against the surface of the substrate in a step S24 and a nozzle is scanned to equally wash the entire surface of the substrate. Scanning and blowing are stopped in a step S25 and the substrate is rotated at a high speed in a step S26 to perform the drainage of the substrate. High pressure pure water is blown against the surface of the substrate by scanning the nozzle while the substrate is rotated. By this constitution, the substrate is certainly washed in a small installation space without damaging an element. Water is drained by the high speed rotation of the substrate and the re-adhesion of dust is prevented and no stain is generated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cleaning a liquid crystal device which is suitable for cleaning a liquid crystal device after a rubbing process.

[0002]

2. Description of the Related Art A liquid crystal device such as a liquid crystal light valve is constructed by sealing a liquid crystal between two substrates such as a glass substrate and a quartz substrate. In a liquid crystal light valve, for example, a thin film transistor (hereinafter, referred to as T
FT) are arranged in a matrix, an opposing electrode is arranged on the other substrate, and the optical characteristics of the liquid crystal layer sealed between the two substrates are changed according to an image signal, thereby enabling image display. I do.

[0003] A TFT substrate on which a TFT is arranged and an opposing substrate arranged opposite to the TFT substrate are manufactured separately.
After both substrates are bonded with high precision in a panel assembly process, liquid crystal is sealed.

In the panel assembling process, first, an alignment film is formed on the opposite surface of the TFT substrate and the opposite substrate manufactured in each substrate process, that is, on the surface in contact with the liquid crystal layer of the opposite substrate and the TFT substrate. Next, a rubbing process is performed. Next, a seal portion serving as an adhesive is formed on one edge of one substrate. The TFT substrate and the opposing substrate are bonded to each other using a sealing portion, and are pressure-bonded and cured while performing alignment. A cutout is provided in a part of the seal portion, and the liquid crystal is sealed through the cutout.

By forming an alignment film and performing a rubbing process, the arrangement of liquid crystal molecules when no voltage is applied is determined. The alignment film is formed, for example, by applying polyimide with a thickness of about several tens of nanometers. By forming an alignment film on the surfaces of both substrates facing the liquid crystal layer, liquid crystal molecules can be aligned along the substrate surface. The rubbing process
This is to form a fine groove on the surface of the alignment film to make the film anisotropically oriented. By subjecting the alignment film to a rubbing treatment in a certain direction, the alignment of liquid crystal molecules can be regulated.

By the way, in such a rubbing process,
A large amount of dust may be generated and adhere to the substrate surface. Therefore, after the rubbing treatment of both substrates, a cleaning process for removing dust adhering to the substrate surfaces is performed.

[0007] The cleaning process after rubbing includes a batch cleaning system, an in-line shower cleaning system, an air blow system, and a tape dusting system. The batch cleaning method is a method in which a substrate is immersed in a pure water tank and cleaned by bubbling or ultrasonic waves. The in-line shower cleaning method is a method of cleaning by spraying a pure water shower on the front and back surfaces while sequentially feeding the substrate by roller conveyance. The air blow method is a method of cleaning the substrate surface by blowing N2 (nitrogen) gas through a filter. In addition, the tape dusting method is a cleaning method in which contaminants are transferred to a tape by attaching and detaching a cleaning tape.

[0008]

However, in the batch cleaning method, there is a high risk that contaminants from the substrate surface will adhere again due to the cleaning, and there is a possibility that the ultrasonic wave may damage the substrate surface. In addition, there is a problem that a large amount of pure water is used. The in-line shower cleaning method has a problem that a shower section, an air knife draining section, and a drying section are required as an apparatus configuration, and a cleaning line is lengthened and a space for installing the apparatus is large.
Further, in the air blow method, there is a problem that the removal performance for surface contamination is inferior. In the tape dust removal method, there is a problem of surface contamination due to reverse transfer of contaminants and adhesives from the cleaning tape.
There has been a problem that damage may be caused by sticking the tape.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a method of cleaning a liquid crystal device, which can surely clean an element in a small space without damaging the element.

[0010]

According to the present invention, there is provided a method of cleaning a liquid crystal device, comprising: a step of mounting a substrate on a rotatable base; a first rotation step of rotating the substrate; And a second rotation procedure of rotating the substrate to drain the water after the spraying of the water is stopped.

According to such a configuration, the substrate mounted on the base is rotated in the first rotation procedure. In the spraying procedure, water is sprayed from a nozzle onto the substrate surface while the substrate is rotating. Thereby, the substrate is cleaned. Second
Is performed by rotating the substrate after the spraying of water is stopped. As a result, the substrate surface dries without dust adhering again.

In one aspect of the method for cleaning a liquid crystal device of the present invention, the spraying step is characterized in that the nozzle is scanned with the nozzle facing the substrate surface.

According to such a configuration, the substrate rotates,
Since the nozzle scans facing the substrate surface, water from the nozzle is sprayed evenly on the entire surface of the substrate, and the entire surface of the substrate is reliably cleaned.

In one aspect of the method for cleaning a liquid crystal device according to the present invention, the second rotating step includes rotating the substrate at a higher speed than the substrate rotating speed in the first rotating step. It is characterized by.

According to such a configuration, the substrate dries in a short time.

In one embodiment of the method of cleaning a liquid crystal device according to the present invention, a wetting procedure before wetting the substrate is added before the spraying procedure. According to such a configuration, since the pre-wetting is performed before spraying the water, the affinity of the substrate surface is improved, and occurrence of a stain in the spraying procedure is prevented.

Further, the pre-wetting procedure of the present invention is characterized in that it is performed on the upper and lower surfaces of the substrate.

According to such a configuration, workability can be improved.

In one aspect of the present invention, the spraying step is characterized in that pure water is sprayed on the substrate.

In the spraying step, high-pressure water is sprayed on the substrate.

According to such a configuration, the detergency is improved.

Further, the spraying step is characterized in that a mixed liquid obtained by mixing an inert gas and water is sprayed on the substrate.

According to such a configuration, the detergency is improved by the bubble effect of the inert gas.

In the spraying step, carbon dioxide is selectively added at the time of spraying the water.

According to such a configuration, even a substrate that is weak to static electricity can be cleaned without damaging it.

[0026]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows the first embodiment of the present invention.
5 is a flowchart illustrating a method for cleaning a liquid crystal device according to the embodiment. FIG. 2 is an equivalent circuit diagram of various elements, wiring, and the like in a plurality of pixels constituting a pixel region of the liquid crystal device. FIG. 3 is a plan view of an element substrate such as a TFT substrate together with components formed thereon viewed from the counter substrate side.
FIG. 4 is a cross-sectional view of the liquid crystal device after the assembly step of bonding the liquid crystal by bonding the element substrate and the counter substrate together, taken along the line HH ′ in FIG. FIG. 5 is a cross-sectional view showing the liquid crystal device in detail. FIG. 6 is a flowchart showing a panel assembling process, and FIG. 7 is a schematic configuration diagram showing a cleaning device employed in the first embodiment.

First, the structure of the liquid crystal panel will be described with reference to FIGS.

As shown in FIG. 3 and FIG. 4, the liquid crystal panel is formed by sealing a liquid crystal 50 between an element substrate 10 such as a TFT substrate and a counter substrate 20. Pixel electrodes and the like constituting pixels are arranged in a matrix on the element substrate 10. FIG. 2 shows an equivalent circuit of an element on the element substrate 10 constituting a pixel.

As shown in FIG. 2, in the pixel area,
A plurality of scanning lines 3a and a plurality of data lines 6a are wired so as to intersect, and pixel electrodes 9a are arranged in a matrix in a region defined by the scanning lines 3a and the data lines 6a. A TFT 30 is provided at each intersection of the scanning line 3a and the data line 6a.
Is connected.

The TFT 30 is turned on by the ON signal of the scanning line 3a, whereby the image signal supplied to the data line 6a is supplied to the pixel electrode 9a. This pixel electrode 9
a and a voltage between the counter electrode 21 provided on the counter substrate 20 is applied to the liquid crystal 50. Further, a storage capacitor 70 is provided in parallel with the pixel electrode 9a, and the voltage of the pixel electrode 9a is held by the storage capacitor 70 for a time longer than the time when the source voltage is applied, for example, by three digits. With the storage capacitor 70, the holding characteristics are improved, and an image with a high contrast ratio can be displayed.

FIG. 5 is a schematic sectional view of a liquid crystal panel focusing on one pixel.

The device substrate 10 made of glass, quartz, etc.
A TFT 30 having a D structure is provided. TFT30
Is provided with a scanning line 3a forming a gate electrode via an insulating film 2 in a semiconductor layer in which a channel region 1a, a source region 1d, and a drain region 1e are formed. The data line 6a is stacked on the TFT 30 via the first interlayer insulating film 4,
Data line 6a is electrically connected to source region 1d via contact hole 5. The pixel electrode 9a is stacked on the data line 6a via the second interlayer insulating film 7, and the pixel electrode 9a is electrically connected to the drain region 1e via the contact hole 8.

When an ON signal is supplied to the scanning line 3a (gate electrode), the channel region 1a becomes conductive,
The source region 1d and the drain region 1e are connected, and an image signal flowing on the data line 6a is supplied to the pixel electrode 9a.

In the semiconductor layer, a storage capacitor electrode 1f extending from the drain region 1e is formed. The storage capacitor electrode 1f is connected to a capacitor line 3b via an insulating film 2 which is a dielectric film.
Are arranged opposite to each other, thereby forming the storage capacitor 70. An alignment film 16 made of a polyimide-based polymer resin is laminated on the pixel electrode 9a and rubbed in a predetermined direction.

On the other hand, the opposing substrate 20 is provided with a first light-shielding film 23 in a region facing the data line 6a, the scanning line 3a, and the region where the TFT 30 is formed on the TFT array substrate, that is, in a non-display region of each pixel. . The first light-shielding film 23 allows incident light from the counter substrate 20 side to pass through the channel region 1a, the source region 1d, and the drain region
Is prevented from entering. An opposing electrode (common electrode) 21 is formed over the entire surface of the substrate 20 on the first light-shielding film 23. An alignment film 22 made of a polyimide polymer resin is laminated on the counter electrode 21 and rubbed in a predetermined direction.

A liquid crystal 50 is sealed between the element substrate 10 and the counter substrate 20. Thereby, TFT3
0 writes the image signal supplied from the data line 6a at a predetermined timing to the layer electrode 9a. In accordance with the written potential difference between the pixel electrode 9a and the counter electrode 21, the orientation and order of the molecular assembly of the liquid crystal 50 are changed, thereby modulating light and enabling gradation display.

As shown in FIG. 3 and FIG.
Is provided with a second light shielding film 42 as a frame for partitioning the display area. The second light shielding film 42 is, for example, the first light shielding film 2
3 is made of the same or different light-shielding material.

A seal material 41 for enclosing liquid crystal is formed between the element substrate 10 and the counter substrate 20 in a region outside the second light shielding film 42. The sealing material 41 is disposed so as to substantially match the contour shape of the counter substrate 20, and fixes the element substrate 10 and the counter substrate 20 to each other. The sealing material 41 is used for the element substrate 1.
A liquid crystal injection hole 78 for injecting the liquid crystal 50 into a gap between the bonded element substrate 10 and the counter substrate 20 which is missing at a part of the center of one side of 0 is formed. After the liquid crystal is injected from the liquid crystal injection port 78, the liquid crystal is sealed with a sealing material 79.

A data line driving circuit 61 and mounting terminals 62 are provided along a side of the element substrate 10 in a region outside the sealing member 41 of the element substrate 10, and along two sides adjacent to the one side. , A scanning line driving circuit 63 is provided. On one remaining side of the element substrate 10, a plurality of wirings 64 for connecting the scanning line driving circuits 63 provided on both sides of the screen display area are provided. In at least one of the corners of the opposing substrate 20, the element substrate 1
A conductive member 65 is provided for electrically connecting the first substrate 0 to the counter substrate 20.

Next, a panel assembling process will be described with reference to FIG. A plurality of element substrates 10 are formed on one mother glass substrate. The substrate (TFT substrate) having the plurality of element substrates 10 and the counter substrate 20 are manufactured separately. In the next steps S2 and S7, polyimide (PI) to be the alignment films 16 and 22 is applied to the TFT substrate and the counter substrate 20 prepared in steps S1 and S6, respectively. Next, in steps S3 and S8, the element substrate 1
0 alignment film 16 and alignment film 22 on the surface of the counter substrate 20
Is subjected to a rubbing process.

Next, in steps S4 and S9, a cleaning step is performed. The cleaning steps of steps S4 and S9 are performed using the apparatus shown in FIG. This cleaning step is for removing dust generated by the rubbing treatment, and is performed before the bonding step.

When the cleaning process is completed, a sealing material 41 (see FIG. 2) is formed in step S5. Then
In step S10, the element substrate 10 and the opposing substrate 20 are bonded to each other, and in step S11, pressure is applied while performing alignment, and the sealing material 41 is cured. Next, in step S12, liquid crystal is sealed from a notch provided in a part of the sealing material 41, and the liquid crystal is sealed by closing the notch. Finally,
In step S13, each cell on the mother glass substrate is divided.

FIG. 7 shows a cleaning apparatus. In FIG. 7, a rotating shaft 112 is provided in a cup 111 so as to be rotatable by a motor (not shown).
A substrate chuck 113 is attached to the upper part of the substrate 2. The substrate chuck 113 can hold the substrate 114 by suction, for example, by vacuum suction. The substrate 114 is, for example, an undivided mother glass substrate on which a plurality of element substrates 10 are configured. By reducing the size of the apparatus in FIG. 6, it is also possible to adsorb and fix the opposing substrate 10 or the element substrate 10 alone to the substrate chuck 113.

Above the substrate chuck 113, a jet nozzle 115 is provided. Jet nozzle 115
Can blow high-pressure pure water toward an arbitrary angle below. Further, the jet nozzle 115 can move horizontally or linearly or arcuately as shown by the dashed arrow in FIG.
14 can be directed to the entire surface.

In FIG. 1, in the cleaning step, first, the substrate 114 is attached in step S21. Substrate 11
4 is attached to the substrate chuck 113. Next, in step S22, the motor is rotated to rotate the substrate chuck 113. As a result, the substrate 114 rotates in a horizontal plane. The number of rotations of the substrate can be set arbitrarily. For example, in step S22, 500 to 2000 rpm (number of rotations /
Minutes).

In the next step S23, a pre-wetting treatment is performed to improve the hydrophilicity. In FIG.
From a nozzle (not shown), pure water for pre-wetting treatment is applied to the substrate 1.
14 is discharged. Next step S
24 is a high pressure water spraying and nozzle scanning step.
For example, pure water is sprayed on the surface of the substrate 114 at high pressure by the jet nozzle 115. In this case, the cleaning with the high-pressure pure water is performed evenly by the pre-wetting treatment.
In the present embodiment, the pressure of the pure water to be sprayed can be freely set within a range of, for example, 1 to 10 MPa. The angle of the jet nozzle 115 is, for example, 5
It can be set arbitrarily in the range of up to 90 °.

Then, the jet nozzle 115 is scanned in the horizontal direction. The number of scans and the speed of the nozzle can be arbitrarily set. Since the jet nozzle 115 is scanned in the horizontal direction while rotating the substrate 114, pure water can be sprayed on the entire surface of the substrate 114.

The next step S25 is a process for stopping scanning and spraying of pure water. In the next step S26, the substrate 114 is rotated at a high speed. In this case, for example, the substrate 114 is rotated in the range of 2000 to 4000 rpm. The remaining water on the surface of the substrate 114 is drained by the centrifugal force caused by the rotation.

Next, the operation of the embodiment configured as described above will be described.

On the substrate 114, a plurality of element substrates 10 shown in FIGS. 2 to 5 are formed. In step S3 of FIG. 6, the alignment film 16 on the surface of the element substrate 10 is subjected to a rubbing process. A large number of dusts adhere to the substrate 114 by this rubbing process.

In the present embodiment, the substrate 114
Is attached to the substrate chuck 113 of the cleaning apparatus shown in FIG. 7 (Step S21). The cleaning operation is performed only in the cup 111 having a size slightly larger than the substrate 114, and the installation space of the apparatus is extremely small.

Next, a motor (not shown) is driven to rotate the substrate 114 (step S22). In this case,
For example, the rotation speed is set in the range of 500 to 2000 rpm. Next, in step S23, pre-wetting is performed by discharging pure water to the surface of the substrate 114. The substrate 114 is rotating,
The entire surface of the substrate 114 is made hydrophilic by the pure water.

In the next step S24, high-pressure pure water of, for example, 1 to 10 MPa is sprayed onto the substrate 114 from the jet nozzle 115, and the jet nozzle 115 is scanned in a horizontal direction or in an arc shape. As a result, high-pressure pure water is evenly sprayed on the entire surface of the
The dust adhering to the surface of the surface is reliably cleaned. In some cases, the angle of the jet nozzle 115 is appropriately changed to adjust the angle at which pure water is sprayed onto the surface of the substrate 114. As a result, the surface of the substrate 114 is more reliably cleaned.

Further, by appropriately setting the nozzle angle and the pressure of the pure water, the pressure on the substrate 114 by spraying the pure water can be adjusted, and the cleaning can be performed without damaging the substrate 114. . Further, since only pure water is sprayed on the substrate 114 and the solid does not physically contact the surface of the substrate 114, no dents, dents, or scratches are generated.

Since the substrate 114 is rotated when pure water is sprayed, the pure water sprayed on the surface of the substrate 114 flows outside the surface of the substrate 114 and drops into the cup 111 from the surface of the substrate 114. Therefore, the surface of the substrate 114 is not stained by the cleaning water. In addition, since cleaning is performed by spraying high-pressure water while rotating the substrate 114, pure water is used as cleaning water, and reliable cleaning can be performed with a relatively small amount of pure water, thereby reducing running costs.

Next, in steps S25 and S26, spraying from the jet nozzle 115 is stopped, and the substrate 114 is rotated at a high speed of, for example, 2000 to 4000 rpm to drain the surface of the substrate 114. Since the substrate 114 is rotated at a high speed, centrifugal force causes the substrate 114 to rotate.
Can be removed in a short time, and reattachment of dust can be prevented.

As described above, in the present embodiment, cleaning is performed by spraying high-pressure water while rotating the substrate, and a compact apparatus is used to prevent re-adhesion of contaminants during cleaning. A stable cleaning effect can be reliably obtained. In addition, high-pressure water can be sprayed evenly on the entire surface of the substrate by the rotation of the substrate and the scanning movement of the nozzle, so that the entire surface of the substrate can be uniformly cleaned. For a substrate that is easily damaged, cleaning can be performed without damaging the substrate by appropriately setting the nozzle angle and the pressure of the high-pressure water. In addition, since no physical contact is made with the solid, no damage occurs on the substrate surface. Also,
Since the substrate is rotated, draining is always performed, and it is possible to prevent occurrence of spots on the substrate surface. In addition, there is an advantage that washing can be performed with a small amount of pure water and running cost is small.

Incidentally, in the present embodiment, various types of cleaning devices can be used. For example, FIG. 8 shows that pure water can be discharged from above and below the substrate so that both surfaces of the substrate can be simultaneously wetted.

In FIG. 8, a mounting table 121 is provided in the cup 111 so as to be rotatable in a horizontal direction about a vertical axis (not shown). At the end of the mounting table 121, for example, three holding pins 123 are provided upright, and the substrate 114 can be mounted and fixed inside the upper end of the holding pin 123. A nozzle 122 capable of discharging pure water is provided at the center of the mounting table 121 so that the back surface of the substrate 114 can be wet with pure water.

Further, the structure shown in FIG. 9 can be adopted as the cleaning device.

In FIG. 9, a mounting table 131 is provided in the cup 111 so as to be rotatable in a horizontal direction about a vertical axis (not shown). At the end of the mounting table 131, for example, three holding members 132 are provided. The holding member 132 is swingably attached to the mounting table 131 so that the substrate 114 can be held between the tips of the holding members 132.

It is clear that the cleaning method of the first embodiment can be carried out using the cleaning apparatus shown in FIGS.

FIG. 10 is a flow chart for explaining the second embodiment of the present invention.

Some substrates are vulnerable to physical damage and static electricity. The present embodiment is applied to this case. 10, the same steps as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

This embodiment is different from the first embodiment in that step S35 is adopted instead of step S24, and step S34 is added. In step S34, carbon dioxide gas is selectively added to pure water when cleaning a substrate which is particularly susceptible to static electricity. In step S35, a mixture of an inert gas such as nitrogen gas and pure water is sprayed.

The cleaning apparatus shown in FIG. 7 is provided with a mechanism for adding carbon dioxide gas to pure water in advance, and can add carbon dioxide gas to the mixed solution.

According to such a structure, since the cleaning is performed with the mixed liquid in which the inert gas and the pure water are mixed, the bubbling effect of the inert gas generated at the time of spraying the mixed liquid causes the bubbling effect of the dust on the substrate surface. High removal effect. Therefore,
Even if the pressure of the mixture is not high, a sufficient cleaning effect can be obtained, so that even a substrate that is vulnerable to physical damage can be cleaned without damaging it. Also,
When the mixture is sprayed at a high pressure, a higher cleaning effect can be obtained.

Further, since it is possible to add carbon dioxide gas in advance, even for a substrate which is weak against static electricity,
It can be cleaned without causing damage.

[0069]

As described above, according to the present invention, there is an effect that the element can be reliably cleaned in a small space without damaging the element.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a method for cleaning a liquid crystal device according to a first embodiment of the present invention.

FIG. 2 is an equivalent circuit diagram of various elements, wiring, and the like in a plurality of pixels forming a pixel region of the liquid crystal device.

FIG. 3 is a plan view of an element substrate such as a TFT substrate as viewed from a counter substrate side together with components formed thereon.

FIG. 4 is a cross-sectional view of the liquid crystal device after the assembly step of bonding an element substrate and a counter substrate and enclosing liquid crystal after completion of the assembly process, taken along the line HH ′ in FIG. 3;

FIG. 5 is a cross-sectional view illustrating a liquid crystal device in detail.

FIG. 6 is a flowchart showing a panel assembling process.

FIG. 7 is a schematic configuration diagram showing a cleaning device employed in the first embodiment.

FIG. 8 is a schematic configuration diagram showing another example of the cleaning device.

FIG. 9 is a schematic configuration diagram showing another example of the cleaning apparatus.

FIG. 10 is a flowchart illustrating a second embodiment of the present invention.

[Explanation of symbols]

 S21: Substrate setting S22: Work rotation procedure S23: Pre-wetting procedure S24: High-pressure water spraying and nozzle scanning procedure S25: Scanning and spraying stop procedure S26: High-speed rotation / draining / drying procedure

Claims (9)

[Claims] A step of mounting a substrate on a rotatable base; a first rotation step of rotating the substrate; a spraying step of directing a nozzle toward a rotating substrate surface and spraying water from the nozzle; A second rotation step of rotating the substrate after the spraying of water is stopped to perform drainage. 2. The method for cleaning a liquid crystal device according to claim 1, wherein in the spraying step, the nozzle is scanned with the nozzle facing the substrate surface. 3. The method according to claim 1, wherein in the second rotation procedure, the substrate is rotated at a speed higher than a rotation speed of the substrate in the first rotation procedure. . 4. The method according to claim 1, wherein a wetting step before wetting the substrate is added before the spraying step.
3. The method for cleaning a liquid crystal device according to item 1. 5. The method according to claim 4, wherein the pre-wetting procedure is performed on upper and lower surfaces of the substrate. 6. The method for cleaning a liquid crystal device according to claim 1, wherein in the spraying step, pure water is sprayed on the substrate. 7. The method according to claim 1, wherein the spraying step sprays high-pressure water on the substrate. 8. The method according to claim 1, wherein in the spraying step, a liquid mixture of an inert gas and water is sprayed on the substrate. 9. The method according to claim 1, wherein in the spraying step, carbon dioxide gas is selectively added at the time of spraying the water.