JP3109693B2 - Cleaning method of alignment film for liquid crystal display panel - Google Patents

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 a surface of a substrate constituting 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") also includes a panel on which control elements such as TFTs, electrodes, etc. are formed. Hereinafter, simply referred to as "work B"), for example, by cleaning a substrate such as glass or plastic, and applying a polymer thin film such as polyimide to the surface thereof by a roll coating method or the like, The alignment film is formed by rubbing a polymer thin film.

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

At present, the cleaning liquid after the alignment treatment is as follows.
It is performed with isopropyl alcohol (hereinafter simply referred to as “IPA”) and water. Usually, cleaning with IPA is performed not only for removing organic impurities on the substrate, but also for improving the wettability of the substrate surface. Further, IPA vapor drying is generally widely used for drying the substrate after cleaning.

[0005]

It is known that the cleaning with IPA and water lowers the alignment force of the alignment film. After investigating the cause, the inventors of the present invention have confirmed through experiments that IPA, which is a cleaning solution, is greatly involved in lowering 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 subjected to IPA cleaning under the condition 1 among the conditions described in [Table 1], as shown in [Table 2], the work was indicated by the condition number corresponding to the above condition. It has stopped at the retardation reduction rate as it is. Regarding the alignment unevenness, as a result of cleaning 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 swells the alignment film. An object of the present invention is to solve the above problems.

[0007]

Therefore, according to the present invention, when cleaning the surface of the alignment film formed on the substrate,
Only pure water as a cleaning solution was washed with, then spin dry method, or were to be dried using only the air knife method. The present invention has solved the above-mentioned problem by such a cleaning method.

[0008]

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

[0009]

Embodiments of the present invention will be described below. In the present invention, when cleaning any of the work A and the work B, the present inventors use “pure water” as a cleaning liquid.
It was used. As used herein, “pure water” is generally sufficient to be “pure water” used for manufacturing a semiconductor integrated circuit device in a semiconductor manufacturing plant. Usually, such "pure water" is water with very little dust or impurities.

[0010] Using such “pure water”, first, the work A (or work B) is subjected to quick dump rinsing in a tank to remove dust having a size of 10 μm or more, and then subjected to ultrasonic waves or the like. Washing is performed, and an overflow rinse is performed to prevent dust from re-adhering to the work. And to dry the work, unlike before,
Spin dry and dry. For this drying, an air knife drying method may be used.

As a result of performing the above-described cleaning with “pure water” under the condition 2 shown in [Table 1], as shown in the condition 2 of [Table 2] corresponding to each condition. It became clear that the rate of decrease in retardation was significantly reduced. Also, even if the cleaning with the “pure water” is performed on the work B,
As shown in [Table 3], it was found that the unevenness occurrence rate was greatly improved to about 20%. In each case, swelling of the alignment film due to “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. 1. Defects caused by insufficient orientation force do not occur. 2. A wide range of liquid crystal materials can be used. The heat treatment required only a small degree of heat treatment, and excellent effects such as failure due to thermal damage did not occur and tact time was improved.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-186817 (JP, A) JP-A-1-291489 (JP, A) JP-A-2-52436 (JP, U) JP-A-4-186 1517 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) G02F 1/1337-1/1337 530 G02F 1/13 101

Claims (2)

(57) [Claims] 1. An alignment film for a liquid crystal display panel, wherein the surface of an alignment film formed on a substrate is cleaned using only pure water as a cleaning liquid and then dried using only spin drying. Cleaning method. 2. A method for cleaning a surface of an alignment film formed on a substrate.
Rinsing with pure water only as a cleaning solution
After that, it is dried using only an air knife.
Method for cleaning an alignment film for a liquid crystal display panel.