KR20040074428A - a method for selectively removing polyimide alignment layer coated on negative photoresist formed on a substrate and recycling the same using a plasma - Google Patents

Abstract

PURPOSE: A method for selectively removing a polyimide organic alignment layer applied to a glass substrate where a negative photoresist is formed by using plasma while reproducing the glass substrate is provided to selectively remove a polyimide organic alignment layer only applied to a negative photoresist by using dry plasma, thereby effectively reproducing a substrate. CONSTITUTION: A polyimide organic alignment layer(102) is applied to a negative photoresist forming glass substrate. The negative photoresist forming glass substrate is injected into a reaction chamber(10) while maintaining pressure at 100 to 900mTorr. The pressure is maintained by injecting O2/N2 mixed gases within the reaction chamber(10). Plasma is generated by applying power to an electrode of a plasma reaction device. The polyimide organic alignment layer(102) is selectively dissolved.

Description

Method for selectively removing polyimide alignment layer coated on negative photoresist formed on a substrate and recycling the same using plasma to selectively remove polyimide organic alignment layer coated on negative photoresist formed glass substrate using a plasma}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for reproducing glass substrates used in LCDs or thin film transistor (LCD) -LCDs. More specifically, the present invention relates to polyimide organic materials coated on negative photoresists formed on glass substrates such as LCD and TFT-LCDs. A method of regenerating a glass substrate by selectively removing the alignment film using dry plasma.

With the development of various flat panel display devices, the development and production of LCD and TFT-LCD are increasing. Such an LCD element is basically composed of glass to apply the electrode on the inner surface of the substrate facing each other, and to form a black matrix (resin BM) using a post spacer (protrusion) or resin thereon, It is comprised by apply | coating a polyimide organic aligning film on it again, injecting a liquid crystal between it, and sealing it.

In the application process of the alignment film, once the glass substrate on which the post spacers are formed is cleaned, the polyimide is printed and pre-cured, and the state of the alignment film is inspected. This is followed by rubbing for the liquid crystal array. In the above process, the pre-fired substrate is inspected and if a defect occurs, it is transferred to the substrate regeneration process to regenerate the substrate, which is the same even after the secondary firing.

Thus, in the manufacturing process of a liquid crystal display element, many cases generate | occur | produce a board | substrate after apply | coating a polyimide organic aligning film to a board | substrate. In the substrate regeneration process, the polyimide alignment film applied to the glass substrate on which the post spacer or the like is formed must be removed. In the past, the polyimide organic alignment film was completely removed by a wet process.

That is, as a conventional wet process for removing the polyimide alignment layer, a solvent such as tetramethyl ammonium hydroxide is added to the polyimide alignment layer coated on the substrate to be regenerated to peel off the polyimide alignment layer (strip fair). Subsequently, the substrate on which the alignment layer has been peeled off is brushed and washed with a neutral solution, and then dried by spin dry to regenerate the substrate.

However, the above-described conventional wet process has the following problems.

First, the peeling method of the polyimide organic alignment layer by the solvent as described above is difficult to remove the alignment layer completely, the quality of the regenerated substrate was not excellent. In the wet process, the solvent applied to the regenerated substrate penetrates between the substrate and the polyimide to exfoliate. In this process, the exfoliation amount of the first penetration site and the later penetration area are different, resulting in uneven peeling. It caused a problem. In particular, it is relatively easy to remove the polyimide alignment layer after the polyimide coating, but after the second firing, since the alignment layer is firmly formed, it is difficult to remove the alignment layer and thus it is impossible to completely reproduce the substrate.

Second, the wet process requires a lot of costs for line equipment and processes for each process, as well as a large work space, and uses a large amount of organic solvents, and therefore, a huge cost is required for a facility for wastewater treatment or reuse. There was even a problem that caused environmental pollution.

Third, as an organic solvent used in the wet process, a negative photoresist such as a post spacer, a protruding resin, or a black matrix using a resin, which is present in whole or in part under the alignment layer, is maintained as it is. It is impossible to selectively peel off only the polyimide alignment film while making it. Therefore, a substrate that has undergone a regeneration by a wet process has a problem in that a negative photoresist such as a post spacer must be formed again.

The present invention was devised to solve the above problems, and selectively uses only a polyimide organic alignment layer coated on a negative photoresist formed on a glass substrate such as an LCD or a TFT-LCD using a dry plasma rather than a conventional wet process. It is an object of the present invention to provide a method of efficiently regenerating a substrate by removing the substrate.

According to the present invention, the polyimide alignment layer can be easily removed even after the secondary firing, and the negative photoresist existing thereunder while efficiently removing the polyimide alignment layer by a dry method using plasma instead of an organic solvent. The substrate regeneration efficiency can be improved by keeping the as is.

1 shows an example of a plasma apparatus employed for removing a polyimide alignment layer and regenerating a substrate according to the present invention.

<Description of main reference symbols in the drawings>

10. Reaction chamber 11. First electrode 12. Second electrode

13. Leading electrode 14. Insulation 15. Power supply

16. Inlet 17. Outlet 100. Target

In order to achieve the above object, a method of regenerating a substrate according to the present invention is applied on a negative photoresist formed on a glass substrate using a plasma apparatus having a reaction chamber for generating a plasma by a high frequency power source applied to an electrode. A method of selectively removing a polyimide organic alignment layer and regenerating a glass substrate, comprising: introducing a negative photoresist forming glass substrate coated with the polyimide organic alignment layer into the reaction chamber and maintaining a pressure at 100 to 900 mTorr; Maintaining the pressure while introducing an O ₂ / N ₂ mixed gas into the reaction chamber; And selectively decomposing the polyimide organic alignment layer by generating a plasma by applying a power of 1 to 20 kwatts to the electrode of the plasma reactor. The mixing ratio of the O ₂ / N ₂ mixed gas introduced into the reaction chamber is preferably 2: 1 to 1: 2 by volume.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms or words used in the specification and claims should not be construed as having a conventional or dictionary meaning, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention. Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiment of the present invention and do not represent all of the technical idea of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations.

1 shows a plasma apparatus for applying a method of removing an alignment layer and regenerating a substrate using a plasma according to the present invention. It is to be understood that the present invention is not limited to the configuration of the illustrated plasma device, and that various modifications can be made within the scope of achieving the object of the present invention.

Looking briefly at the plasma reactor illustrated in the present embodiment, the first electrode 11, which is one of the parallel plate electrodes, is installed in the reaction chamber 10, and the second electrode 12 is installed on the upper portion opposite thereto. The object to be processed 100 is placed on the first electrode 11. The object to be processed 100 is, for example, judged to be defective in the TFT-LCD substrate manufacturing process and is reproduced. The glass substrate 101 is disposed on the glass substrate 101 to maintain a distance from an opposing substrate (not shown) during the assembly process. A negative photoresist 103 such as a plurality of post spacers, MVA mode protrusion for securing a wide viewing angle, or a black matrix using a resin (resin BM) is formed. The negative photoresist 103 may be manufactured by a photolithography process using a conventionally applied photoresist.

The first electrode 11 is connected to the drawing electrode 13 extending out of the reaction chamber 10, and the drawing electrode 13 is connected to the power supply 15 again to supply high frequency power for generating plasma. Receive. The lead electrode 13 is insulated from the reaction chamber 10 by the insulating portion 14.

In addition, a second electrode is provided on the side opposite to the first electrode 11 in the reaction chamber 10 to excite the reaction gas in the reaction vessel 10 to generate a plasma as described later.

The reaction chamber 10 is formed with an inlet 16 for injecting a reaction gas for plasma generation and an outlet 17 for discharging the gasses.

Then, the process of removing the alignment layer of the substrate according to the present invention using the above apparatus will be described.

First, the object 100 to be processed is introduced into the reaction chamber 10. At this time, the pressure in the reactor is maintained at about 100 mTorr ~ 900 mTorr. Subsequently, the reaction gas is introduced into the reaction chamber 10 through the gas inlet 16, wherein a mixed gas of O ₂ and N ₂ is used as the gas. At this time, the pressure in the reaction chamber 10 is maintained as it is even when the gas is introduced.

Subsequently, a high frequency power source of 1 to 20 kwatts is applied from the power supply 15 to the electrode 11 to generate an O ₂ / N ₂ plasma. The highly reactive gas is then dissociated, excited and ionized as follows.

O ₂ → O + OO + e → O ^* + e

O ₂ + e → O ₂ ^* + e O ₂ → O ₂ ⁺ + e

^{_{O 2 → 2O + + 2e 2O}} 2 + → O - + O 3

^{O + e → O - O +} 2e → O 2 -

N ₂ → N + NN + e → N ^* + e

N ₂ + e → N ₂ ^* + e N ₂ → N ₂ ⁺ + e

^{_{N 2 → 2N + + 2e N}} + e → N -

N + 2e → N ^2- N + 3e → N ^3-

This reaction step is displayed the second, third reaction mixture is, the _{^{O 2 +, O -, O}} 3, N -, N 2-, N 3- , etc. is obtained to again momentarily e ^* O, O ₂ Unstable and highly reactive radicals such as ^* , O ₃ ^* , N ^* , N ₂ ^* are produced.

The generated radicals break down molecular bonds of the polyimide constituting the alignment layer 102 of the object 100 to decompose into organic molecules of nitrogen, oxygen, and carbon. The decomposed polyimide organic molecules are combined with oxygen and nitrogen present in the reaction chamber to form CO, CO ₂ , NO, NO ₂ , H ₂ O, etc., and are discharged through the outlet 17 in the gas phase. Looking at it as follows.

C ^{- +} O + → CO

O ^{- +} O + → O ₂

N ^- + O ₂ → NO ₂ ⁺

N ^- + O → NO ⁺

According to the invention this reaction occurs evenly across the substrate.

Meanwhile, the radical ions may be partially or entirely present under the alignment layer 102 of the substrate, a black matrix using a resin or MVA mode protrusion or a resin for securing a wide viewing angle. Has a limited reactivity with respect to the negative photoresist 103, such as). That is, the negative photoresist 103 is a composition including a binder, a photocrosslinker, a photoinitiator, a solvent, and other additives, and unlike the positive photoresist, the molecular weight of the binder is greatly increased by a reaction such as crosslinking and photodimerization by exposure. While thermal properties, chemical resistance, and reaction stability are significantly increased, the decomposition of radicals is difficult to perform. Especially, the mixed N ₂ gas further improves the decomposition resistance of radical negative ions of the negative photoresist to negative photoresist. Let them survive. The main component of the formed negative photoresist is a (meth) acrylate polymer is mainly used in addition to the polyvinyl alcohol-based and polyisoprene-based polymers. In addition, various kinds of binders as disclosed in Korean Patent Application Publication No. 1998-22330 A polymer may be used, and any negative photoresist having an improved decomposition resistance to radicals by reaction such as crosslinking by exposure may be used according to the object of the present invention. In consideration of the decomposability to the polyimide alignment film and the decomposability of the negative photoresist, the most suitable O ₂ / N ₂ mixed gas mixing ratio is 2: 1 to 1: 2 by volume.

As such, the polyimide alignment layer 102 applied over the glass substrate may be selectively and uniformly removed while maintaining the negative photoresist material partially or wholly present under the alignment layer by O ₂ / N ₂ plasma etching. The effect of the present invention will be more clearly understood through the following experiment.

Experimental Example

Color filter layer consisting of pigment-dispersion type negative photoresist (containing benzyl methacrylate / methacrylic acid from Fuji Film Arch, Japan) as a spin coating method on a glass substrate of size 600 × 700 × 0.7 mm ³ And a 500 μm thick polyimide alignment layer were continuously injected into a plasma reactor having a volume of 100 liters, and vacuum was formed. The mixed O ₂ / N ₂ gas (1: 1) was 1,500 sccm (Standard Cubic Centimeter per Minute (quantity at 0 ° C., 1 atm) was applied to the electrode with a power of 2 kwatt to generate a plasma and reacted for 40 seconds.

Subsequently, after completion of the reaction, the substrate was taken out of the reactor and the surface thereof was observed. As a result, it was confirmed that all of the polyimide alignment layer was removed, and there were no defects for 1024 × 765 cells of the substrate. In addition, when the color sensitivity change of the color filter layer formed under the alignment film of the board | substrate was measured, it was observed that it was less than 2%, and it confirmed that it remained almost as it was.

The organic alignment film removing method of the substrate according to the present invention has the following advantages.

First, since the present invention removes the polyimide organic alignment layer by a dry process in the plasma reactor, it does not need a large sized equipment and the operation cost is low, and the maintenance and operation is easier and easier than the conventional wet process.

Second, in the conventional wet process, it is difficult to remove the polyimide alignment layer after secondary firing, but according to the present invention, the polyimide membrane can be completely removed even after secondary firing. This means that it is difficult to remove the conventional alignment film, so that the discarded substrate can be reproduced more effectively.

Third, since the polyimide alignment layer is removed by a plasma dry process, there is no need to use a large amount of organic solvents used in the conventional wet process, thereby preventing problems such as environmental pollution.

Fourth, since the components of the polyimide organic alignment film decomposed according to the present invention are removed in a gaseous phase, an additional step such as washing the regenerated substrate with a neutral solution and drying it is unnecessary.

Fifth, in the conventional wet process, there is a difference in the degree of removal of the alignment film at the corners and the center of the substrate where the peeling phenomenon occurs due to the organic solvent, so that the regeneration is not uniform and the regeneration failure rate is relatively high. By removing the alignment layer as a whole by the chemical reaction used, there is no difference in the degree of removal and the defect rate can be significantly reduced.

Sixth, the conventional wet process removes not only the polyimide alignment layer but also negative photoresist materials such as a spacer partially or wholly present by using a large amount of highly soluble organic solvent, but in the present invention, O ₂ / By limiting the reactivity with the negative photoresist using the N ₂ mixed gas, it is possible to selectively remove the alignment film. This can improve substrate regeneration efficiency and shorten subsequent manufacturing processes.

Claims (2)

A method of selectively removing a polyimide organic alignment layer applied on a negative photoresist formed on a glass substrate by using a plasma apparatus having a reaction chamber for generating plasma by a high frequency power source applied to an electrode, and regenerating the glass substrate, Inserting a negative photoresist forming glass substrate coated with the polyimide organic alignment layer into the reaction chamber and maintaining a pressure at 100 to 900 mTorr; Maintaining the pressure while introducing an O ₂ / N ₂ mixed gas into the reaction chamber; And Selectively decomposing the polyimide organic alignment layer by generating a plasma by applying a power of 1 to 20 kwatts to the electrode of the plasma reactor; coating on the glass substrate on which the negative photoresist is formed; A method of selectively removing the polyimide organic alignment layer and regenerating the glass substrate. The method of claim 1, The mixing ratio of the O ₂ / N ₂ mixed gas is 2: 1 to 1: 2 volume ratio to selectively remove the polyimide organic alignment layer applied on the glass substrate on which the negative photoresist is formed to regenerate the glass substrate Way.