JPH09288275A - Method for removing oriented film and device for removing oriented film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for measuring film thicknesses which is highly reliable and is simple at the time of measuring the film thickness of the oriented film formed on the substrate of a liquid crystal display element by using a stylus method. SOLUTION: A plate 4 having a slit-shaped slotted part is set on the substrate 1 formed with the oriented film 13 on the uppermost layer. An elastic material 5 consisting of a resin material is brought into contact with the oriented film 3 from this slotted part and is slid to partly remove the oriented film, by which only the oriented film 3 is removed without simultaneously removing the film formed on the layer lower than the oriented film 3. As a result, the reliability of the measured value of the film thickness is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to removal of an alignment film, which selectively removes only the alignment film when the film thickness of the alignment film formed on a substrate used for a liquid crystal display device is measured by a stylus method. A method and an alignment film removing apparatus.

[0002]

2. Description of the Related Art As shown in FIG. 5, a structure of a liquid crystal display device is such that an underlayer film 22 such as an insulating film made of ITO (Indium Tin Oxide) or a transparent resin and an alignment film for defining the alignment direction of liquid crystal molecules. The liquid crystal 24 is held between a pair of substrates 21 on which the liquid crystal 23 is formed, and the periphery is sealed with a sealant 25. The alignment film 23 is made of a polymer material such as polyimide and is formed in the uppermost layer in contact with the liquid crystal. The alignment film 23 is generally formed by an offset printing method, a spin coating method, or the like.

The alignment film 23 is subjected to an alignment treatment by a rubbing method or the like, which defines the alignment direction of liquid crystal molecules in contact with the alignment film.

In order to properly perform the above-mentioned alignment treatment and obtain good display quality as a liquid crystal display element, it is necessary to optimize various processes and maintain them even at the time of forming the alignment film prior to the alignment treatment. is there. In particular, the control of the film thickness of the alignment film is one of the very important items because it has a great influence on the alignment characteristics such as the pretilt angle of liquid crystal molecules. High measurement methods are always required.

This film thickness can be measured with extremely high accuracy by using a scanning electron microscope.
Since the device is large-scale and very expensive, it is not realistic to use it for controlling the film thickness of the alignment film.

As another method for measuring the thickness of a thin film, which has been conventionally used, light is used as a probe to measure the transmission or reflection characteristics of a target film having a known optical constant, such as the ellipsometry method. Then, there is a method of calculating the film thickness from the obtained information. This method has an advantage that the film thickness of the target film can be measured in a non-contact and non-destructive manner, and therefore even after the film thickness is measured, the subsequent steps are not affected.

However, in the method of using light as a probe, it is necessary to know the optical constant of the target film in advance. Normally, the alignment film is an ultrathin film having a film thickness of several hundred angstroms or less. Since it is formed on a multi-layered substrate on which a large number of transparent electrodes, insulating films, etc. are formed, the optical constant may change during firing. Further, since the substrate as a whole constitutes a very complicated optical system, it is often difficult to accurately interpret the optical characteristics obtained from the probe. Therefore, the reliability of the optical constant, which is indispensable for determining the film thickness, cannot be obtained, so that the reliability of the measured value decreases. Further, the thin films formed on the liquid crystal display element are laminated so that the optical characteristics thereof are as close as possible, so that considerable accuracy is required to read these differences accurately. Therefore, there is a problem in that considerable equipment and time are required to overcome these difficulties.

Still another thin film thickness measuring method is as follows:
A part of the target film is removed by a cutter knife, and the probe is pressed against a region including a step between the remaining part and the removed part of the target film, and scanning is performed so as to cross the step. There is a stylus method that calculates the film thickness from the amount of displacement of the needle.

When this stylus method is used, a removed portion is formed in the alignment film, and rubbing failure occurs during the subsequent rubbing process, so that it cannot be applied to all substrates. However, in general, when controlling the film thickness of the thin film formed by the offset printing method or the spin coating method as described above, it is difficult for these methods to cause the variation in the film thickness for each substrate, and it takes about several hours. Since a variation with respect to each certain period is more likely to occur, a method is adopted in which one substrate is extracted by punching every predetermined period, and the film thickness of this substrate is measured and controlled.

The stylus method has an advantage that measurement can be performed more easily than a method using light as a probe.

[0011]

However, when the film thickness of the alignment film formed on the substrate of the liquid crystal display element is to be measured by the above-mentioned stylus method, there are the following problems.

Since a thin film made of a transparent resin layer or the like is usually formed in the lower layer of the alignment film, the blade edge of the cutter reaches the lower layer film when the alignment film is removed by a cutter knife, and only the alignment film is formed. Was very difficult to remove, and there was the problem that the reliability of the measured values was reduced.

To solve the problem in the stylus method, Japanese Patent Laid-Open No. 3-150894 discloses a method of forming a film thickness check hole at the same time as a via hole during film formation in a film thickness management method for a multilayer thin film circuit board. However, since it is not necessary to form a hole in the alignment film that is usually formed in the liquid crystal display element, if a new film thickness check hole is attempted to be formed, the number of steps increases correspondingly, which is not convenient. I have a problem. Further, when using the offset printing method, it is possible to perform patterning by using a format in which a film thickness check hole is formed in advance.
As described above, there is a problem that rubbing failure occurs during the rubbing process. Further, it is conceivable that patterning is performed using a format in which a film thickness check hole is formed only when the film thickness is measured by punching every predetermined period, but a thin film is formed using the offset printing method. In this case, the film thickness of the thin film formed tends to fluctuate even when the format is exchanged, so that there is a problem that the reliability of the measured value is completely lost.

Further, a method of removing a part of the alignment film by plasma etching can be considered, but it requires a large-scale apparatus and is used for controlling the film thickness of the alignment film in terms of cost and simplicity. Not relevant.

The present invention has been made in view of the above problems, and in measuring the film thickness of the alignment film of a liquid crystal display element, the advantage of the stylus method of simplicity is utilized, and the measurement is performed reliably. In order to do so, the present invention provides an alignment film removing method and an alignment film removing apparatus that can selectively remove only the alignment film.

[0016]

In the method for removing an alignment film according to claim 1 of the present invention, the film thickness of an alignment film made of a polymer material formed on a substrate used in a liquid crystal display device is measured by a stylus method. At this time, a method of removing the alignment film, which is a first step of removing a part of the alignment film by bringing an elastic body made of a resin material into contact with the alignment film and sliding the elastic body. And a second step of cleaning the removed portion of the alignment film generated by the first step.

The method for removing an alignment film according to a second aspect of the present invention is the method for removing an alignment film according to the first aspect, wherein:
In the step of (1), when a part of the alignment film is removed using an elastic body made of a resin material, a plate having a slit-shaped hollow portion is interposed between the elastic body made of the resin material and the alignment film. Then, the elastic body is brought into contact with and slid on the alignment film through the slit-shaped hollow portion.

According to a third aspect of the present invention, in the alignment film removing apparatus, a stage for fixing the substrate on which the alignment film is formed, and a resin provided so as to be in contact with and slidable on the surface of the substrate on which the alignment film is formed. An alignment film removing means for removing the alignment film, which has an elastic body made of a material, and a cleaning means for cleaning a portion of the substrate where the alignment film is removed by the alignment film removing means. To do.

The operation of the above configuration will be described below. In the method for removing an alignment film according to claim 1 of the present invention, the alignment film is removed by bringing an elastic body made of a resin material into contact with the alignment film and sliding the same, that is, bringing the elastic body into contact with the alignment film. A frictional force is generated by rubbing in the state of being made, and the alignment film is removed by the frictional force, so that the lower layer film of the alignment film is not removed at the same time.
Since it is possible to selectively remove only the alignment film,
The reliability of the film thickness measurement value obtained by the stylus method can be improved.

In the method for removing an alignment film according to a second aspect of the present invention, an elastic body made of a resin material is brought into contact with and slid on the alignment film through a slit-shaped hollow portion to remove a part of the alignment film. Since it is removed, the removed portion and the remaining portion of the alignment film can coexist in a limited region.

In the alignment film removing apparatus according to the third aspect of the present invention, it is possible to realize the alignment film removing method as described above.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIGS. FIG. 1 is a cross-sectional view showing a step of measuring the film thickness of an alignment film formed on a liquid crystal display element by a stylus method using the alignment film removing method of the present invention. 1 is a glass substrate, 2
Is a lower layer film made of ITO or an insulating film, and 3 is an alignment film.

First, as shown in FIG. 1 (b), a plate 4 having slit-shaped hollow portions is set on a substrate on which an alignment film 3 is formed as the uppermost layer. Next, FIG.
As shown in (c), a part of the alignment film 3 is removed by bringing the elastic body 5 made of a resin material into contact with and sliding on the alignment film 3 from the slit-shaped hollow portion.
A step is formed between the remaining portion and the removed portion. After part of the alignment film 3 is removed, as shown in FIG. 1D, cleaning is performed by blowing air 7 to remove the foreign matter 6 generated when part of the alignment film 3 is removed. . Further, as shown in FIG. 1E, the probe 8 is scanned so as to cross the step while contacting a region including the step between the remaining portion and the removed portion of the alignment film, and the probe is caused by the step. The film thickness is calculated from the displacement amount of 8.

Incidentally, in order to remove the foreign matter 6 generated when a part of the alignment film 3 is removed, a chemical such as acetone may be wiped off instead of blowing air.

As described above, in the present invention, when the film thickness is measured by the stylus method, the alignment film which is the target film is removed by using the elastic body made of the resin material instead of the cutter knife. Therefore, only the alignment film can be selectively removed, and the reliability of the film thickness measurement value obtained by the stylus method can be improved. This is because the alignment film formed on the substrate of the liquid crystal display element is generally formed of a polyimide-based polymer resin or an amide-based polymer resin, but since these materials have almost no affinity with other substances, the lower layer film. Since the adhesion strength to and is not so large, it is more suitable to scrape off with an elastic body made of a resin material than to scrape off with a cutter knife.

Usually, when measuring the film thickness by the stylus method, the distance that the probe can scan is about 2 mm, so it is necessary to make both the removed portion and the remaining portion coexist within this range. In the present invention, since the alignment film 3 is removed by contacting and sliding the elastic body 5 made of a resin material with the alignment film 3, the removal portion and the remaining portion remain within a range of 2 mm without using the plate 4. It is difficult to make both department and department coexist. Therefore, it is preferable that the plate 4 is used to coexist the removed portion and the remaining portion of the alignment film within a limited range.

Next, an alignment film removing apparatus for removing the alignment film from the substrate on which the alignment film is formed will be described below with reference to FIG.

FIG. 2 is a schematic view of an alignment film removing apparatus of the present invention, which includes a stage 10 for fixing a substrate 9 and an alignment film removing means 1 for selectively removing the alignment film formed on the substrate 9.
1, a cleaning unit 12 for cleaning foreign substances generated when the alignment film is removed, and a control unit 13 for controlling each unit.

In the present embodiment, the stage 1
0 is provided with an adsorption hole so that the substrate 9 can be adsorbed and fixed.

The alignment film removing means 11 is composed of an extendable and retractable arm 14 and an elastic body 15 made of a resin material provided in front of the arm 14, and the elastic body 15 is fixed to the stage 10 by suction. The alignment film formed on the substrate 9 can be brought into a contact state or a non-contact state. Further, the elastic body 15 comes into contact with the alignment film formed on the substrate 9 and slides.

Further, the cleaning means 12 is equipped with an air gun 16 having an air ejection port, and the ejection port of the air gun 16 faces the contact point between the elastic body 15 and the alignment film formed on the substrate 9. Therefore, the elastic body 15 can blow off the foreign matter generated when the alignment film on the substrate 9 is removed by the jet air.

A method of removing the alignment film by the alignment film removing apparatus having the above structure will be described with reference to the flow chart of FIG.

First, as shown in FIG. 3A, the substrate 9 is adsorbed and fixed at a predetermined position on the stage 10. Next, as shown in FIG. 3B, the alignment film removing means 11
Then, the cleaning means 12 is moved to a predetermined position, the arm 14 provided in the alignment film removing means 11 is extended, and the elastic body 15 provided at the tip of the arm 14 is brought into contact with the alignment film formed on the substrate 9. . Next, as shown in FIG. 3C, the elastic body 15 is slid to remove the alignment film formed on the substrate 9. Next, as shown in FIG. 3D, air is ejected from the air gun 16 provided in the cleaning means 12 to blow away foreign matters generated by removing the alignment film.
Next, as shown in FIG. 3E, the alignment film removing means 11 and the cleaning means 12 are retracted, and the substrate 9 is removed.

In the alignment film removing device, the alignment film removing means 11 and the cleaning means 12 may be fixed and the substrate 9 may be moved.

If desired, a plate having a slit-shaped hollow portion may be interposed between the substrate 9 and the elastic body 15. In this case, it is necessary that the plate does not wobble when the elastic body 15 slides on the alignment film on the substrate 9. This may be fixed on the stage 10, for example.

FIG. 4 shows that the film thickness is measured at 10 locations on one substrate by the film thickness measurement method by the stylus method using the alignment film removing method of the present invention and the conventional film thickness measurement method by the stylus method. The measurement results are shown. In the alignment film removing method of the present invention, a commercially available plastic eraser was used as the elastic body 15. The accurate film thickness of this substrate was measured with a scanning electron microscope and found to be 450 Å. As can be seen from this figure, the film thickness measuring method by the stylus method using the alignment film removing method of the present invention has higher reliability of the measured value than the conventional film thickness measuring method by the stylus method. .

In the present embodiment, in measuring the film thickness of the alignment film, a step of removing the alignment film,
Although the step of measuring the film thickness of the alignment film by using the probe pin is performed by using a different device, the alignment film removing device of the present invention is provided with a step measuring means provided with the probe pin, and the control unit 13 is provided. It may be controlled by.

[0038]

As described above, according to the method for removing an alignment film of the present invention, since the alignment film is removed by using the elastic body made of the resin material, the alignment film can be aligned without removing the lower layer film of the alignment film. Since only the film can be selectively removed, the reliability of the measured value by the stylus method can be improved.

Further, since a part of the alignment film is removed by bringing an elastic body made of a resin material into contact with and sliding on the alignment film through the slit-shaped hollow portion, the alignment film removal part and the remaining part are removed. Has the effect of being able to coexist in a limited area.

Further, by using the alignment film removing apparatus of the present invention, it is possible to easily and selectively remove only the alignment film.

[Brief description of drawings]

FIG. 1 is a flow chart showing a process of film thickness measurement by a stylus method using an alignment film removing method of the present invention.

FIG. 2 is a schematic view showing an alignment film removing apparatus of the present invention.

FIG. 3 is a flow chart showing a step of removing an alignment film using the alignment film removing apparatus of the present invention.

FIG. 4 is a diagram showing the results of film thickness measurement values of the present invention and the prior art.

FIG. 5 is a diagram showing a cross-sectional shape of a liquid crystal display element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glass substrate 2 Lower layer film 3 Alignment film 4 Plate 5 Elastic body made of resin material 6 Foreign matter 7 Air 8 Probe 9 Substrate 10 Stage 11 Alignment film removing means 12 Cleaning means 13 Control section 14 Arm 15 Elastic body made of resin material 16 Air gun

Claims (3)

[Claims] 1. A method for removing an alignment film formed of a polymer material formed on a substrate used for a liquid crystal display device when the film thickness is measured by a stylus method, the method comprising a resin material. A first step of removing a part of the alignment film by bringing the elastic body into contact with the alignment film and sliding the elastic body, and cleaning a removal part of the alignment film generated by the first step A second step; and a method for removing an alignment film, comprising: 2. In the first step, when a part of the alignment film is removed using an elastic body made of a resin material,
A plate having a slit-shaped hollow portion is interposed between the elastic body made of the resin material and the alignment film, and the elastic body is brought into contact with and slid on the alignment film through the slit-shaped hollow portion. The method for removing an alignment film according to claim 1, wherein 3. An alignment film, comprising: a stage for fixing a substrate having an alignment film formed thereon; and an elastic body made of a resin material provided slidably in contact with the alignment film formation surface of the substrate. An alignment film removing apparatus comprising: an alignment film removing unit for removing the alignment film; and a cleaning unit for cleaning a portion of the substrate where the alignment film is removed by the alignment film removing unit.