KR101171316B1 - Method for repairing working stage with CNT antistatic treatment - Google Patents

Abstract

The present invention provides a method for repairing a CNT antistatic treatment work stage. The repairing method of the CNT antistatic treatment stage of the present invention includes a washing step, a preheating step, a coating step, and a thermosetting step. The cleaning step cleans certain parts of the work stage that need repair. The preheating step preheats the specific site. The coating step coats the repair solution containing carbon nanotubes on the specific portion. The thermal curing step thermally cures the specific site coated with the repair solution. According to the present invention, it is possible to repair CNT antistatic work stage quickly and simply in the field.

Description

Method for repairing working stage with CNT antistatic treatment

The present invention relates to an antistatic work stage, and more particularly, to a method for repairing an antistatic work stage that can protect the work from static electricity by mounting a flat work such as a substrate. .

The work stage used in the semiconductor manufacturing apparatus is a substrate on which a wafer is placed and is usually made of a metallic material. In the semiconductor manufacturing apparatus using the work stage, after the handler fixes the wafer substrate and moves to the work stage, tribostatic static electricity occurs between the work stage and the wafer substrate when the wafer substrate is placed on the work stage.

In addition, the work stage used in the flat panel display (FPD) dispenser usually adsorbs the display substrate in a vacuum manner. The work stage in this case is also usually made of a metallic material, and when the display substrate is adsorbed on the work stage or when the display substrate which was fixed to the adsorption is detached from the work stage, charging occurs in the work stage, so that the display It is charged to the substrate. In recent years, as the display substrate is enlarged, the amount of charging increases, so that the problem of electrostatic charging increases.

A plurality of electronic components such as semiconductor devices are disposed on the wafer substrate and the display substrate. Therefore, when static electricity is generated, it may be applied to the electronic component and transferred to the internal circuit. This, in turn, will seriously damage the reliability of the electronic components. In addition, there is a problem in that particles are attached to the substrate or the substrate is broken when the substrate is lifted up due to the electrostatic charging.

Conventionally, in order to prevent the charging of the static electricity, an ionizer is installed in the work stage to neutralize the charging potential. In this case, however, lift-up is not possible, and the ion wind of the ionizer does not reach, and even when lift-up occurs, static electricity generated between the work stage and the substrate is generated instantaneously, such as a discharge occurs before the ion wind reaches a place where neutralization is required. The problem of peeling charge caused by

In order to solve this problem, in order to prevent the static electricity of the work stage can be coated with a fluorine resin (aka, Teflon coating). Since the fluorine resin has a small adsorption energy with other substances, excellent non-tackiness, and a small coefficient of friction, the fluorine resin has a small correlation with the glass substrate, and thus a small amount of static electricity generated by peeling.

In this case, since the normal fluorine component has insulation, the teflon coating contains a charged material in the fluorine component. That is, by anodizing the work stage and then applying Teflon coating, it is possible to prevent the generation of static electricity in the work stage.

However, the Teflon coating method is relatively expensive to manufacture. In particular, in the case of the dispenser, as the size of the display substrate is increased, the size of the work stage is also increased, so that the manufacturing cost is inevitably higher.

In addition, since the hardness of the fluorine itself is low, the hardness of the coating film made of fluorine is low, and scratches easily occur. As a result, it is difficult to maintain flatness of the scratched portion, which causes particles to occur.

In addition, since fluorine has an insulating property, a filler such as carbon black or a conductive polymer should be added to have an antistatic sheet resistance. Carbon black has a problem that dust is generated as a spherical shape. , An excessive amount of binder should be used, and there is a problem that it is difficult to form a thin film.

On the other hand, if a very small damage is caused to a specific part of the antistatic work stage, a large voltage is collected in that part, thereby causing a great electrical damage to a work product such as a substrate. Therefore, the damaged part should be subjected to antistatic coating again.

By the way, the existing anodizing treatment or fluorine coating is impossible to repair a specific site. Accordingly, even if there is damage to a very small part of the work stage, the front surface of the work stage has to be subjected to the antistatic coating again. This increases the repair cost and lengthens the repair time.

In particular, to perform the antistatic coating again, the work stage must be moved to a separate location for the antistatic coating. Accordingly, the number of workers for repair is inevitably increased, and the repair is inconvenient.

The present invention is to solve various problems including the above problems, while minimizing the generation of static electricity on the surface meeting the substrate of the stage, the manufacturing cost is reduced, the sheet resistance can be properly adjusted, the friction coefficient is low It is an object to provide a work stage with improved wear resistance.

Another object of the present invention is to provide a method for repairing an antistatic work stage, wherein the repair of the antistatic stage is simple and the repair time can be shortened.

Therefore, the repairing method of the CNT antistatic treatment stage according to the preferred embodiment of the present invention includes a washing step, a preheating step, a coating step, and a thermosetting step. In this case, the CNT antistatic work stage includes a work stage on which an electronic component is mounted, at least a surface on which the work is seated is made of a conductive material, and at least the substrate of the work stage is seated. One surface is coated to prevent the charge between the workpiece and the work stage, it means that the antistatic material including a carbon non-tube coating film is coated.

The washing step washes the specific site. The preheating step preheats the specific site. The coating step coats the repair solution containing carbon nanotubes on the specific portion. The thermal curing step thermally cures the specific site coated with the repair solution.

In this case, in the repair solution, the carbon nanotubes are within 10w%. In addition, the repair solution may contain a mass percentage of 10 wt% or less as at least one selected from acrylic, urethane, polyester, epoxy, polyimide, melamine, conductive polymer, ceramic, and organic / inorganic hybrid binders. It is preferable to have a binder which has.

In this case, the repair solution preferably contains a water-soluble dispersant. In addition, the particle size in the repair solution is preferably 10 μm or less in length, 1 μm or less in diameter, and the viscosity of the repair solution is preferably 1 cps to 2 cps or less.

On the other hand, the sheet resistance of the coating film formed by coating the repair solution is preferably 10 ⁵ ~ 10 ¹⁰ Ω / □.

On the other hand, the preheating step, preheating the specific site to 80 ℃ to 100 ℃, the thermosetting step, it can be made by maintaining the specific site at a temperature of 120 ℃ to 200 ℃ 30 minutes.

After the thermosetting step, acetone, toluene, ethanol, dimethylformamide (NN-Dimethyl Formamide, DMF), isopropyl alcohol (Isopropyl Alcohol, IPA), methyl ethyl ketone (Methyl Ethyl Ketone, MEK) selected from the group consisting of It may further comprise the step of removing contaminants by rubbing at least any one, after sprinkling the specific site.

In this case, the repair solution includes a water-soluble dispersant, and the contaminant removing step may include ² kg / cm ² after spraying the acetone. To At a pressure of 7kg / cm ² It can be done by rubbing several times.

According to the present invention, by coating an antistatic material including CNTs, the friction coefficient of the work stage is low and the wear resistance is excellent.

In addition, the work stage requiring repair can be easily repaired in the field, and the repair work is simplified, thereby reducing the cost and reducing the repair time.

1 is a perspective view showing an example of a CNT antistatic work stage according to a preferred embodiment of the present invention.
2 is a cross-sectional view showing a cross section of the upper side of the work stage in FIG.
3 is an enlarged cross-sectional view of part A of FIG. 2.
4 is a modification of FIG. 3.
5 is a flowchart showing each step of the method for repairing a CNT antistatic treatment work stage according to a preferred embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a perspective view showing an apparatus including a work stage which is anti-static treatment of CNTs of the present invention and which requires repair at a specific site.

The apparatus includes a work stage 20 and a base frame 10 supporting the work stage.

The work stage 20 is mounted above the base frame 10. The work stage 20 and the base frame 10 may be integrally formed or may be combined with each other as separate components. On the work stage 20 a work 4 comprising electronic components is seated.

An example of the workpiece may be a wafer substrate or a display substrate. In this case, the apparatus to which the work stage 20 is applied may be a semiconductor manufacturing apparatus on which the wafer substrate is seated or a dispenser on which the display substrate is seated. The present invention is not limited to this, but it is obvious that the present invention is applied to all work stages that require antistatic. On the other hand, the reference numeral 30 is a rail that can move the head for the operation.

It is damaged on the specific site D of the work stage. In this case, damage is a case where the sheet resistance exceeds 10 ¹⁰ Ω / □ or the antistatic coating is peeled off.

FIG. 2 is a cross-sectional view taken along the line II-II of FIG. 1. As shown in FIG. 2, one surface of the work stage 20 is coated with a carbon nanotube coating layer 25.

The work stage 20 is usually made of a metal material such as aluminum. In this case, an anodizing process may be performed on the upper surface of the work stage 20. Anodizing is the use of an electrochemical reaction to apply an artificial oxide coating to the surface of unsurfaced aluminum. Surface abrasion is prevented by the anodizing treatment, and there is an effect of preventing corrosion. In this case, the work stage 20 may be divided into a first stage portion 22 in which the work is directly closed, and a second stage portion 21 supporting the first stage portion.

The carbon nanotube coating layer 25 is formed on a surface on which the substrate of the work stage 20 is seated, and includes carbon nanotubes (CNTs). CNTs form a tube in which one carbon is combined with another carbon atom in a hexagonal honeycomb pattern, and the diameter of the tube is extremely small, at the nanometer level, and thus exhibits unique electrochemical characteristics.

CNTs have excellent mechanical properties, electrical selectivity, and excellent field emission characteristics. If such a CNT is formed as a thin conductive film on the stage, it has high conductivity and thus has an antistatic effect. In addition, since the CNTs constitute networks with each other in a tube shape instead of a spherical shape, there is little possibility of dust and excellent moisture resistance.

The CNTs may be selected from single-walled carbon nanotubes, double-walled carbon nanotubes, multi-walled carbon nanotubes and bundled carbon nanotubes, and combinations thereof.

In addition, carbon nanotubes on which the surface of carbon nanotubes is modified by acid treatment, or carbon nanotubes having different properties such as metallicity and semiconductivity, may be selected.

The coating solution including the carbon nanotubes may include a suitable dispersant. Specific examples of the dispersant include sodium dodecyl sulfate (SDS), triton X (Sigma), Tween20 (polyoxyethyelene Sorbitan Monooleate), CTAB (Cetyl Trimethyl Ammonium Bromide) is mentioned.

The carbon nanotube coating film 25 can be adjusted so that the sheet resistance is 10 ⁵ ~ 10 ¹⁰ Ω / □. The sheet resistance is at an appropriate level to prevent the generation of static electricity at the stage. If the sheet resistance exceeds 10 ¹⁰ Ω / □, the electrical conductivity is not good and the effect of dissipating static electricity on the stage to the outside is small. If the sheet resistance is 10 ⁵ Ω / □ or less, its electrical conductivity is too high. Cursors may affect adjacent electronic components.

The carbon nanotube coating layer 25 may include a binder. The binder may be an acrylic, urethane, polyester, epoxy, polyimide, melamine, conductive polymer or organic / inorganic hybrid binder. The binder may be a thermosetting resin or a photocurable resin.

In this case, the carbon nanotubes included in the carbon nanotube coating layer 25 may be single-walled, double-walled or multi-walled carbon nanotubes.

The carbon nanotube coating layer 25 may have a thickness of 0.1 μm to 100 μm.

Meanwhile, as shown in FIG. 3, an adhesion promoting layer 23 may be formed between the carbon nanotube coating layer 25 and the work stage 20. The adhesion promotion layer 23 functions to improve adhesion between the carbon nanotube coating layer 25 and the work stage 20. In this case, the adhesion promotion layer 23 may be made of a single molecule, oligomer, or polymer material having a carboxylic acid group, anhydride group, or phosphonic acid group capable of chemisorption with the aluminum oxide surface. The adhesion promotion layer 23 may have a thickness of about 1 nm to about 1 μm.

In this case, the binder included in the carbon nanotube coating layer 25 may be a single molecule or a polymer having a bonding force with the adhesion promotion layer 23.

Therefore, as shown in FIG. 3, after the upper surface of the work stage 20 is anodized 22a, the adhesion promotion layer 23 and the carbon nanotube coating layer 25 mixed with the binder are sequentially stacked. Can be.

A protective layer 26 may be formed on the outer surface of the carbon nanotube coating layer 25. The protective layer 26 further improves the durability and wear resistance of the carbon nanotube coating layer 25 while protecting the surface of the carbon nanotube coating layer 25 from the outside while maintaining antistatic performance. In this case, the protective layer 26 may use an inorganic material, an organic single molecule and a high molecular compound, or an organic or inorganic hybrid material, and the thickness thereof may be 0.1 μm to 100 μm.

In the conventional antistatic coating of fluorine material, since the hardness of the fluorine is weak, the thickness of the protective layer is inevitably thickened. Due to the thickness, the antistatic effect is reduced. However, in the case of the present invention, since the carbon nanotube coating film has excellent abrasion resistance and excellent bonding strength with the protective layer, the thickness thereof can be minimized.

In this case, the protective layer may be formed of a ceramic-based, because the ceramic-based protective layer has a high chemical resistance, and has a strong durability in acetone, alcohols and the like.

Meanwhile, as shown in FIG. 4, an inner binder layer 24 may be interposed between the carbon nanotube coating layer 25 and the work stage 20. That is, after the inner binder layer 24 is first coated on the upper surface of the work stage 20 subjected to the anodizing 22a, the carbon nanotube coating layer 25 may be coated on the upper surface of the inner binder layer 24. In this case, an adhesion promoting layer 23 may be interposed between the inner binder layer 24 and the work stage 20.

The inner binder layer 24 may be coated on the work stage 20 using bar coating, slit die coating, dip coating, spin coating, spray coating, screen coating, ink jet coating, or the like. In addition, the carbon nanotube coating layer 25 may be coated on the inner binder layer 24 by using bar coating, slit die coating, dip coating, spin coating, spray coating, screen coating, ink jet coating, or the like. have.

In addition, the adhesion promotion layer 23 may be applied on the work stage 20 using bar coating, slit die coating, dip coating, spin coating, spray coating, screen coating, ink jet coating, or the like.

In this case, it is preferable that the addressing material of the inner binder layer 24 is made of acrylic, urethane, polyester, epoxy, polyimide, melamine, conductive polymer, and organic / inorganic hybrid binders. For example, the urethane-based address material is coated on the work stage with a high adhesive force and at the same time the carbon nanotube coating film 25 is coated with a high adhesive force. Therefore, the address material greatly improves the adhesive force between the work stage and the carbon nanotube coating film. 4, a protective layer 26 may be formed on the outer surface of the carbon nanotube coating layer.

5 is a flowchart illustrating each step of the method for repairing a CNT antistatic treatment work stage according to an embodiment of the present invention.

As shown in FIG. 5, the repairing method according to a preferred embodiment of the present invention includes a washing step S10, a preheating step S20, a coating step S30, and a thermosetting step S40. . In addition, the contaminant removing step (S50) may be further roughened after the thermosetting step.

Referring to each step with reference to Figs. 5 and 2, the washing step (S10) is a step of washing the specific area (D) required for repair, before repair. Preheating step (S20) is a step of preheating the specific site. Coating step (S30) is a step of coating the repair solution containing the CNT to the specific site. The thermosetting step (S40) is a step of thermosetting a specific portion coated with the repair solution. The contaminant removing step is to remove unnecessary substances remaining after the thermosetting step.

When describing each step in detail, the first washing step (S10) is to wash the specific site (D) to be repaired. The washing step is to remove contaminants such as carbon nanotube coating film remaining in a specific portion (D) of the work stage 20. In order to remove contaminants, various methods such as washing with distilled water, washing with acid, and adding a reagent for changing a dispersant may be used. Among them, washing with an acid can wash the surface and remove the internal residual dispersant, and a method of adding a reagent for changing the dispersant can break the surface wash and the dispersant into unit molecules to wash the water better.

In the present invention, the washing step (S10) is more preferably performed in the order of pure water washing, acetone washing and drying. Pure water refers to water in which ions (mainly alkalis and metal ions) are removed from ordinary water. Pure water is more preferably ultrapure water that has removed other impurities (such as organic) that are not ionized.

Acetone cleaning quickly removes moisture from the work stage. This is more necessary when the CNTs forming the carbon nanotube coating film 25 are dispersed with a water-soluble dispersant. Examples of the water-soluble dispersant include sodium dodecyl sulfate (SDS), triton x-100 (tx-100), sodium dodecylbenzene sulfonate (NaDDBS), and gum arabic. The water-soluble dispersant has advantages such as the most stable solution and maximum solubility, and thus has the advantage of effectively dispersing carbon nanotubes. That is, a dispersion solution of more than a certain concentration is required to form a carbon nanotube conductive film having excellent dispersion rate. For this purpose, it is advantageous to use a water-soluble dispersant.

On the other hand, in the washing step, it may be a fluorine coating on the fine portion by the damage. In other words, when damage occurs to a specific part, the center part is dug while the edge protrudes outward. In this case, the center portion may be dug deeper than the anodized layer to pierce the metal portion. Rather than repairing the metal part directly, the outer protruding edge portion is polished so that the upper surface of the work stage is flat. In this case, the area to be coated may be further washed with acetone after washing with ultrapure water.

Thereafter, a preheating step S20 is performed. The preheating step is to increase the coating power of the repair solution to be described later. That is, when the working stage is in the state of 80 ℃ to 100 ℃, coating the carbon nanotube-containing repair solution is because the coating power is improved.

Thereafter, the coating step (S30) is passed. The coating step may be performed using bar coating, slit die coating, dip coating, spin coating, spray coating, screen coating, inkjet coating, brush coating, and the like.

In this case, spray coating using an air brush or direct coating using a brush is more preferable, since this is a coating method that can be easily performed in the field.

In the case of the spray coating spray at a constant flow rate (8 to 16 cc / min) and a constant air pressure (2 to 4 bar), a predetermined time (2 to 8 seconds) at a distance (100 mm to 200 mm) away from the work stage surface After drying. For example, after setting the airbrush to air pressure of 3 bar at a flow rate of 12 cc / min, it is sprayed for 5 seconds at a distance of 150 mm from the surface of the work stage and dried. The drying after spraying is repeated several times.

For brush coating, apply the appropriate amount to the brush so that the solution does not clump, then apply it to a specific area and then dry. This process is repeated several times.

The repair solution includes a CNT and a binder. CNTs have a mass percent of up to 10 w% and can be single-walled, double-walled or multi-walled carbon nanotubes.

The binder may be at least one selected from acrylic, urethane, polyester, epoxy, polyimide, melamine, conductive polymer, fluorine, ceramic, and organic / inorganic hybrid binders.

On the other hand, the repair solution further comprises a dispersant. The dispersant functions to help the dispersion of the CNTs efficiently. In detail, in the synthesis step, the CNTs generate a physical aggregation of μm and chemical aggregation of several tens of nm between nanotubes. Such agglomeration phenomena prevent the formation of three-dimensional network structure in the conductivity implementation and reduce the conductivity efficiency compared to the particles. For example, failure to overcome physical cohesion is very similar to the use of spherical particles at the μm level rather than nanotubes, and further, theoretical percolation concentrations cannot be achieved without chemical coagulation. Therefore, a dispersant is included so that CNT can be efficiently dispersed.

As one of the CNT dispersion methods, the carbon nanotubes may be dispersed in ultrasonic waves in an organic solvent such as amide-based DMF (NN-dimethylformamide) or NMP (1,2-dichlorobenzene, N-methylpyrrolidone). This dispersion method has a problem of poor stability because it is dispersion by simple dissolution, and also has a very low solubility of carbon nanotubes.

As another method of CNT dispersion, a water-soluble dispersant may be applied. Examples of the water-soluble dispersant include sodium dodecyl sulfate (SDS), triton x-100 (tx-100), sodium dodecylbenzene sulfonate (NaDDBS), and gum arabic. The water-soluble dispersant has advantages such as the most stable solution and maximum solubility, and thus has the advantage of effectively dispersing carbon nanotubes. That is, in order to form a carbon nanotube conductive film having excellent dispersion rate, a dispersion solution of a certain concentration or more is required. For this purpose, it is advantageous to use a water-soluble dispersant. In this case, the dispersant preferably has a mass percentage of 10 wt% or less.

In the coating step, it is possible to coat a sufficient degree of flatness even in the prior art, and after that, by polishing the slightly raised portion using sandpaper and abrasive, its height can be adjusted.

After that, the heat curing step (S40). The thermosetting step is such that the repair coating film formed by coating the repair solution can be firmly adhered to the work stage.

It is preferable that the particle size in the said repair solution is 10 micrometers or less in length, and 1 micrometer or less in diameter.

In addition, the viscosity of the repair solution is preferably 1cp to 2cp or less.

In the thermosetting step, the coating site is heated to 100 ° C. to 200 ° C. with an IR heater or a dry heater, and is maintained for a predetermined time (eg, 30 minutes). When the work stage is heated to 200 ° C. or more, there is a possibility that heat deformation occurs in the work stage. For example, in the case of the dispenser, when the work stage is deformed at 10 μm or more, a problem occurs in the work.

After the thermosetting step, the contaminant removing step S50 may be further performed.

The pollutant removal step is selected from the group consisting of acetone, toluene, ethanol, dimethyl formamide (NN-Dimethyl Formamide, DMF), isopropyl alcohol (IPA), methyl ethyl ketone (MEK) It is achieved by sprinkling at least one of the above and then rubbing.

Most dispersants act as impurities after the repair coating film is formed. Accordingly, in order to have a sheet resistance in the correct range, it is preferable to remove the dispersant after coating. The dispersant may be mixed with the CNT in a solvent and coated on the substrate with a mixed solution, usually the solvent is removed by evaporation. The dispersant, however, is not completely removed by evaporation and remains with the CNTs.

If the dispersant is water-soluble, it is preferable to remove the dispersant using acetone. In this case, after properly spraying acetone on the coating part, use a clean wiper to apply a suitable pressure (for example, 2 kg / cm ^2). To 7kg / cm ² ) while rubbing at a constant speed. For example, after sprinkling acetone, rub it at a rate of 5 kg / cm ² and rub it about 500 times at a speed of 2 Hz.

According to the present invention, it is possible to easily repair a work stage that has been treated with CNT antistatic treatment in the field.

As described above, although described with reference to the preferred embodiment of the present invention, those skilled in the art various modifications and variations of the present invention without departing from the spirit and scope of the invention described in the claims below I can understand that you can.

10: base frame 20: work stage
23: adhesive coating layer 24: inner binder layer
25: carbon nanotube coating film 26: protective layer
D: specific area S10: washing step
S20: preheating step S30: coating step
S40: thermal curing step S50: contaminant removal step

Claims (8)

A workpiece including an electronic component is seated, and at least a surface on which the workpiece is seated is prevented from being charged between the workpiece and the work stage on a work stage made of a conductive material and at least one surface of the substrate on which the work stage is seated. Coated with an antistatic material comprising a carbon nontube coating film, and repaired when damage occurs to a specific part of the antistatic treated work stage coated with
Washing the specific site;
Preheating the specific site;
Coating a repair solution containing carbon nanotubes on the specific portion;
Thermally curing a specific portion coated with the repair solution;
Repair method of the CNT antistatic treatment stage comprising a. The method of claim 1,
In the repair solution, the carbon nanotubes are within 10w%,
The repair solution is:
At least one selected from acrylic, urethane, polyester, fluorine, epoxy, polyimide, melamine, conductive polymer, ceramic, and organic-inorganic hybrid binders having a binder having a mass percentage of 10 wt% or less. The repair method of the CNT antistatic treatment work stage characterized by the above-mentioned. The method of claim 2,
Wherein said repair solution comprises a water soluble dispersant. The method of claim 2,
The particle size in the repair solution is 10 µm or less in length and 1 µm or less in diameter,
The repair solution of CNT antistatic treatment stage, characterized in that the viscosity of the repair solution is 1cp to 2cp or less. The method of claim 1,
The sheet resistance of the repair coating film formed by coating the repair solution is 10 ⁵ ~ 10 ¹⁰ Ω / □ Repair method of the CNT anti-static treatment stage, characterized in that. The method of claim 1,
The preheating step, preheating the specific site at 80 ℃ to 100 ℃,
The thermosetting step, characterized in that for maintaining the specific site for 30 minutes at a temperature of 120 ℃ to 200 ℃ CNT anti-static treatment process repair method. 7. The method according to any one of claims 1 to 6,
After the thermosetting step,
At least one selected from the group consisting of acetone, toluene, ethanol, dimethylformamide (NN-Dimethyl Formamide, DMF), isopropyl alcohol (IPA) and methyl ethyl ketone (MEK), the specific The method for repairing a CNT antistatic treatment stage, further comprising the step of removing contaminants by sprinkling after spraying on the site. The method of claim 7, wherein
The repair solution comprises a water-soluble dispersant,
The pollutant removal step, 2kg / cm ² after spraying the acetone To At a pressure of 7kg / cm ² A method for repairing a CNT antistatic treatment stage, comprising rubbing several times.

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