JPH063671A - Cleansing method for orientation film for liquid crystal display panel - Google Patents

Abstract

PURPOSE:To prevent sink of the orienting force of an orientation film formed on a liquid crystal display panel. CONSTITUTION:An orientation film is formed on the surface of a base board on the color filter side or on the TFT, etc., formed over the board surface. The surface of this orientation film is cleansed with pure water, etc., and dried by a physical drying method such as the spin-dry method or air knife method. This does not involve a sink of the orientation force, allows use of a wide variety of liquid crystal materials, permits to manage with a light degree of heat treatment, and prevents yielding no-good items due to heat damages and shortage of the orientation force.

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 an alignment film formed on the surface of a substrate which constitutes a liquid crystal display panel.

[0002]

2. Description of the Related Art Conventionally, for example, in manufacturing a TFT type liquid crystal display panel, a panel on a color filter side (hereinafter, simply referred to as "work A") is a panel on which control elements such as TFTs and electrodes are formed. (Hereinafter, simply referred to as “work B”), those substrates, such as glass and plastic, are washed, and a polymer thin film such as polyimide is applied to the surface thereof by a roll coating method or the like. The polymer thin film is rubbed into an alignment film.

Usually, when this rubbing process is performed, foreign substances such as dust generated in that case adhere to the substrate, and in order to remove such foreign substances, cleaning is performed after the rubbing process.

At present, as a cleaning liquid after this orientation treatment,
It is performed with isopropyl alcohol (hereinafter, simply referred to as “IPA”) and water. Usually, the cleaning with IPA is performed for the purpose of removing organic impurities on the substrate and also for improving the wettability of the substrate surface. Further, IPA vapor drying is generally frequently used for drying after cleaning the substrate.

[0005]

It is known that washing with IPA and water reduces the alignment force of the alignment film. The inventors of the present invention have investigated the cause of this, and have confirmed by experiments that IPA, which is the cleaning liquid, is greatly involved in the reduction of the alignment force. The quality of the alignment state can be determined by the retardation value and the alignment unevenness.

Regarding the retardation value, when the work was IPA cleaned under the condition 1 among the conditions shown in [Table 1], as shown in [Table 2], the condition number corresponding to the condition was shown. The rate of retardation decrease seems to have occurred. Regarding the alignment unevenness, as a result of washing with the current method (IPA and water), it was confirmed that 100% of the alignment unevenness occurred as shown in [Table 3]. This is because IPA causes the alignment film to swell. The present invention aims to solve the above problems.

[0007]

Therefore, in the present invention, when cleaning the surface of the alignment film formed on the substrate,
Pure water was used as a cleaning liquid for cleaning, and thereafter, physical drying methods such as a spin dry method and an air knife method were used for drying. The present invention has solved the above problems by such a cleaning method.

[0008]

Therefore, the swelling of the alignment film is reduced, and the retardation value and the alignment unevenness are improved, so that the alignment force is not reduced.

[0009]

Embodiments of the present invention will be described below. According to the present invention, when cleaning either the work A or the work B, the present inventors use “pure water” as the cleaning liquid.
It was used. The "pure water" referred to here is usually "pure water" used for manufacturing a semiconductor integrated circuit device in a semiconductor manufacturing factory. Usually, such "pure water" is water with very little dust and impurities.

Using such "pure water", first, the work A (or the work B) is removed by a quick dump rinse to remove dust having a size of 10 μm or more, and then ultrasonic waves are applied. While cleaning and performing an overflow rinse to prevent dust from reattaching to the work piece. And to dry the work, unlike the conventional,
It was dried by spin drying. An air knife drying method may be used for this drying.

As a result of performing the above-mentioned washing with "pure water" under the condition 2 described in [Table 1], as shown in condition 2 of [Table 2] corresponding to each condition. , It was clarified that the rate of retardation decrease was remarkably reduced. In addition, even if the work B is washed with "pure water",
As shown in [Table 3], it was found that the unevenness occurrence rate was significantly improved to about 20%. In any case, swelling of the alignment film with "pure water" was not observed.

[0012]

[Table 1]

[0013]

[Table 2]

[0014]

[Table 3]

[0015]

As described above, according to the present invention, the orientation force does not decrease. No defects will occur due to insufficient orientation force. A wide range of liquid crystal materials can be used. The heat treatment was light, no defects such as heat damage occurred, and the takt time was improved.

Claims (3)

[Claims] 1. An alignment film for a liquid crystal display panel, characterized in that when cleaning the surface of an alignment film formed on a substrate, it is cleaned by using pure water as a cleaning liquid, and then dried by a physical drying method. Cleaning method. 2. The method for cleaning an alignment film for a liquid crystal display panel according to claim 1, wherein the physical drying method is a spin dry method. 3. The method for cleaning an alignment film for a liquid crystal display panel according to claim 1, wherein the physical drying method is an air knife method.