KR20080034140A - Method and device for removing conductive metal oxide thin film - Google Patents

Abstract

[PROBNLEMS] A method and a device for removing a conductive metal oxide thin film without leaving a scar nor stress deformation. [MEANS OF SOLVING PROBLEMS] The device comprises a first electrode (18) disposed so as to immerse one end thereof into electrolyte (17), a second electrode (13) disposed so as to immerse one end thereof into electrolyte (17) to allow the one end to face a conductive metal oxide thin film (11) so that the conductive metal oxide thin film (11) of a base material (12) immersed in the electrolyte (17) in a treating bath (16) acts as a cathodes, and a power supply (14) for applying a dc voltage so that the second electrode (13) acts as an anode and the first electrode (18) as a cathode. A dc voltage is applied to the both electrodes (13, 18) to remove the conductive metal oxide thin film (11) by a reduction reaction. [EFFECTS] A conductive metal oxide thin film can be efficiently removed without causing a scan nor stress deformation, and hence an expensive functional glass substrate or the like can be recycled.

Description

METHOD AND DEVICE FOR REMOVING CONDUCTIVE METAL OXIDE THIN FILM}

The present invention relates to a method for removing a conductive metal oxide thin film formed on a substrate by sputter deposition or the like so as to be reused, and an apparatus for implementing the method.

For example, a high-performance glass substrate on which ITO (an oxide of indium and tin and a transparent conductive film) is formed has excellent optical performance (transmittance, etc.) and mechanical performance (flatness, etc.). Is used. However, since this high-performance glass substrate is expensive, when the ITO formed on the surface does not satisfy the quality control standard, the ITO is removed and reused to reduce the cost.

As a method of removing conductive metal oxide thin films, such as ITO, there exist a method of removing by mechanical abrasion, or the method of removing by chemical etching. The former method is to remove the conductive metal oxide thin film formed on the surface of the workpiece 1 by abrasion by the polishing brush 2, as shown in FIG.

In addition, the latter method is to remove the conductive metal oxide thin film formed on the surface by immersing the workpiece 1 in the chemical liquid 3 that chemically dissolves the conductive metal oxide thin film as shown in FIG. For example, patent document 1, 2).

Patent Document 1: Japanese Patent Application Laid-Open No. 6-321581

Patent Document 2: Japanese Patent Application Laid-Open No. 9-86968

However, since the method of removing by mechanical abrasion is to rub a polishing brush, abrasions (wounds) and stress deformation may be generated on the surface of a workpiece. If you have scratches, you will not be able to reuse it. In addition, when the target object is a flat panel display, since the glass thickness of a glass substrate is about 0.5 mm, there exists a possibility that it may be damaged by the mechanical abrasion of a contact system. Therefore, a delicate brush pressure adjustment is required, and a long time is required for complete peeling.

On the other hand, the method of removing by chemical etching uses a strong acid or a strong alkali chemical solution, so it is necessary to pay sufficient attention to handling, resulting in poor workability and wastewater treatment of the used electrolyte solution. In addition, the recovery of the rare metal requires a separate extraction operation, which is very uneconomical.

The problem to be solved by the present invention is that in the method by mechanical abrasion, scratches and stress deformation occurs, the substrate can not be reused, and subtle pressure adjustment of the brush is required, it takes a long time for complete peeling, chemical In the etching method, not only the workability is deteriorated, but also the wastewater treatment of the used electrolyte solution is required, and additional extraction work is required for recovery of the rare metal, which is uneconomical.

Method for removing the conductive metal oxide thin film of the present invention,

In order to remove the conductive metal oxide thin film of a base material without leaving abrasion marks, stress deformation, etc., and without using a strong acid or strong alkali chemicals,

A base material which has a conductive metal oxide thin film immersed in electrolyte solution,

A first electrode immersed in electrolyte solution,

A second electrode immersed in an electrolyte solution and disposed to face the conductive metal oxide thin film,

The main feature is that the conductive metal oxide thin film is removed by a reduction reaction by applying a voltage such that the first electrode is the cathode and the second electrode is the anode.

In the method for removing the conductive metal oxide thin film of the present invention, the conductive metal on the surface of the substrate after the reduction reaction may be removed by, for example, abrasion by a flexible body such as a sponge or jet of jet water. The remaining conductive metal can be reliably removed without causing scratches or editing layers on the substrate surface.

In the present invention described above, it is possible to efficiently remove the conductive metal formed on the substrate by using an electrolyte having a resistivity of 10 ² Ω · cm to 10 ⁶ Ω · cm.

Method for removing the conductive metal oxide thin film of the present invention,

A first electrode arranged to immerse at least one end in the electrolyte;

A second electrode disposed so that at least one end is immersed in the electrolyte solution so that the conductive metal oxide thin film of the substrate immersed in the electrolyte solution in the processing tank becomes the cathode, and the one end is opposed to the conductive metal oxide thin film;

It can be implemented by using the apparatus of the present invention having a power supply for applying a voltage such that the second electrode is an anode and the first electrode is a cathode.

The first electrode or the second electrode of the conductive metal oxide thin film removing device of the present invention is in a flat plate shape inclined in a non-contact state with the electrolyte above the substrate so that the electrolyte flows on the conductive metal oxide thin film of the substrate. When the structure is provided with the electrolyte supply mechanism for supplying the electrolyte solution to the flat plate-shaped first electrode or the second electrode, the thickness of the electrolyte layer on the conductive metal oxide thin film can be reduced, and the removal efficiency is improved. .

In the conductive metal oxide thin film removing device of the present invention, when a moving mechanism such as the base material and the second electrode is provided, the conductive metal formed on the surface of the base material can be efficiently removed.

In the above-described conductive metal oxide thin film removing apparatus of the present invention, it is preferable that the first electrode and the second electrode are disposed such that the first electrode passes over the conductive metal oxide thin film of the substrate before the second electrode. . This is because the conductive metal oxide thin film in the vicinity of the second electrode where voltage is applied to the anode generates a reducing action. When moved in the reverse direction, a portion where the conductive reaction is lost due to the reduction reaction passes through the electrodes. This is because there is a possibility that it cannot be formed.

Moreover, in the electroconductive metal oxide thin film removal apparatus of the said invention, when the electrolyte solution in the said processing tank is guide | induced to electrolyte solution supply mechanism or the said injection mechanism, and the said electrolyte solution is comprised so that circulation use is possible, the amount of electrolyte solution required is at least.

(Effects of the Invention)

In the present invention, since the conductive metal formed on the substrate is removed after weakening the adhesion by non-contact electrolytic elution, the conductive metal oxide thin film can be efficiently removed without leaving scratches or stress deformation on the substrate. It is possible to reclaim and use expensive functional glass substrates to be used. In addition, since no strong acid or strong alkali chemicals are used, environmental load can be reduced, and resource cycles such as a base metal and a rare metal are also possible, which is economically advantageous.

1 is a view showing the basic principle of the present invention.

2 is a view for explaining a first example of the device of the present invention for implementing the method of the present invention.

3 is a view for explaining a second example of the device of the present invention for implementing the method of the present invention.

4 is a view for explaining a third example of the device of the present invention for implementing the method of the present invention.

5 is a view for explaining a fourth example of the device of the present invention for implementing the method of the present invention.

6 is a view for explaining a fifth example of the device of the present invention for implementing the method of the present invention.

7 is a view for explaining a sixth example of the device of the present invention for implementing the method of the present invention.

8 is a view showing an example of a recovery apparatus after the electrolytic reduction treatment of the conductive metal oxide thin film using a fourth example of the apparatus of the present invention.

It is a figure explaining the method of removing a metal thin film by mechanical abrasion.

It is a figure explaining the method of removing a metal thin film by chemical etching.

(Explanation of the sign)

11: conductive metal oxide thin film 11a: conductive metal

12: description 13: second electrode

14: power supply 15: rotating sponge

16: Processing bath 17: Amount of electrolyte

18: first electrode 19: circulation tank

20: pump 22: spray nozzle

The present invention weakens the adhesion by non-contact electrolytic elution to remove the conductive metal oxide thin film of the substrate without leaving scratches, stress deformation, or the like, and without using a strong acid or strong alkali chemical solution. After making it, it implement | achieved by removing the electroconductive metal formed in the base material.

Example

Hereinafter, after explaining the basic principle of the method of this invention using FIG. 1, the best form for implementing this invention is demonstrated in detail using FIGS.

The present invention is a non-contact processing method that does not leave scratches or stress deformation on the substrate, and is a method of removing a conductive metal oxide thin film that does not use strong acid or strong alkali.

That is, in this invention, as shown in FIG. 1, the base material 12, such as an insulator or an electrically conductive material which has the conductive metal oxide thin film 11, and the 1st electrode 18 and the 2nd electrode 13 are processed into a processing tank ( It is immersed in the electrolyte solution 17 in 16. Then, for example, a DC voltage or a pulse voltage is applied from the power supply 14 so that the first electrode 18 becomes the cathode and the second electrode 13 becomes the anode.

In this manner, a reduction reaction occurs in the conductive metal oxide thin film 11 and metallized to weaken the bond with the substrate 12. The conductive metal 11a which has become weakly bonded to the substrate 12 is reliably removed from the substrate 12 by, for example, a flexible body such as a rotating sponge 15, which is rubbed with a weak stress. In addition, a non-contact method such as jet water flow may be used instead of the flexible body.

That is, in the present invention, for example, a DC voltage is applied so that the base 12 on which the conductive metal oxide thin film 11 is formed, the first electrode 18 is a cathode, and the second electrode 13 is an anode. In this case, the surface portion of the conductive metal oxide thin film 11 facing the anode of the second electrode 13 becomes a cathode, and hydrogen / oxygen ions and fine bubbles start to be generated from the surface of both electrodes by electrolytic action. .

On the surface of the conductive metal oxide thin film 11, H ₂ is generated by this electrolytic action, but this H ₂ becomes a reducing agent to generate an action of removing O ₂ in the conductive metal oxide thin film. In addition, since the generation of H ₂ occurs at the interface of the conductive metal oxide thin film, a highly efficient reduction reaction occurs.

The conductive metal oxide thin film, which is free of the bond by O ₂ , is made of only a metal element, thereby weakening the bonding strength to the surface of the substrate. The conductive metal consisting only of this metal element can be easily removed by abrasion of weak stress by a flexible body such as a sponge, or jet flow.

The method for removing the conductive metal oxide thin film of the present invention is based on the above basic principle, and is performed by using the conductive metal oxide thin film removing device of the present invention shown in FIG.

FIG. 2 shows the first electrode 18 in contact with the conductive metal oxide thin film 11 above the substrate 12 in which the conductive metal oxide thin film 11 is immersed in the electrolyte solution 17 of the processing bath 16 toward the liquid surface. ) And the second electrode 13 are arranged in parallel and immersed.

Then, for example, when a direct current voltage is applied from the power supply 14 so that the first electrode 18 becomes the cathode and the second electrode 13 becomes the anode, the power supply 14 (+)-second electrode 13- A closed circuit of the electrolytic solution 17-the conductive metal oxide thin film 11-the electrolytic solution 17-the first electrode 18-the power source 14 (-) is formed, and the vicinity of the second electrode 13 applied as the anode is formed. Fine bubbles of hydrogen are generated from the surface of the conductive metal oxide thin film 11.

At this time, H ₂ generated on the surface of the conductive metal oxide thin film 11 in the vicinity of the second electrode 13 becomes a reducing agent, thereby causing the action of removing O ₂ in the conductive metal oxide thin film 11. In addition, since the generation of H ₂ occurs at the interface of the conductive metal oxide thin film 11, an efficient reduction reaction occurs.

The conductive metal oxide thin film 11, which is not bonded by O ₂ , is made of only a metal element and exists in a state in which a bonding force is weakened on the surface of the substrate 12. The conductive metal 11a, which has become weakly bonded to the substrate 12, is removed from the substrate 12 by being rubbed with a weak stress by the rotating sponge body 15 disposed downstream of the second electrode 13.

The conductive metal oxide thin film removing apparatus of the present invention is not limited to the configuration shown in FIG. 2, and may be the configuration shown in FIGS. 3 to 7.

FIG. 3 shows the first electrode 18 inclined in a non-contact state with the electrolyte solution 17 above the substrate 12 such that the electrolyte solution 17 flows on the conductive metal oxide thin film 11 of the substrate 12. It consists of a flat plate shape.

In FIG. 3, the electrolyte 17 of the processing tank 16 is once circulated to supply the electrolyte 17 in the processing tank 16 to the flat plate-shaped first electrode 18 that is inclined. 19 is received, and is sent to the first electrode 18 by the pump 20. When accommodating this electrolyte solution 17 in the circulation tank 19, when the metal mixed in the electrolyte solution 17 is removed through the filter 21, the base material 12 at the time of abrasion by the rotating sponge body 15 is carried out. The wound can be prevented.

In addition, in the apparatus of the present invention having the configuration shown in FIG. 3, the second electrode 13 and the rotating sponge body 15 are integrated into one. In the structure shown in FIG. 4, the conductive metal oxide thin film 11 is rubbed off at the same time as reduction, and is reliably removed from the base material 12. As shown in FIG.

5 is provided with an injection nozzle 22 for injecting jet water flow on the surface of the substrate 12 instead of the rotating sponge 15 of the apparatus of the present invention having the configuration shown in FIG. 2, and the electrolyte solution to the injection nozzle 22. FIG. Supply of (17) is made to circulate and supply the electrolyte solution 17 in the process tank 16 like FIG. By removing the conductive metal 11a, which has become weakly bonded to the substrate 12 due to the jet flow from the jet nozzle 22, it is possible to reliably prevent the substrate 12 from being damaged.

6 is provided with the injection nozzle 22 instead of the rotating sponge 15 of the apparatus of this invention of the structure shown in FIG. 3, and supplying the electrolyte solution 17 to this injection nozzle 22 is carried out with the processing tank 16. In FIG. The internal electrolyte solution 17 is supplied and circulated for use.

FIG. 7 shows the present invention having the configuration shown in FIG. 2 in which the second electrode 13 and the injection nozzle 22 are integrated into one.

In these examples shown in FIGS. 3 to 7, the metal mixed in the electrolyte 17 is removed by passing through the filter 21. Instead, as shown in FIG. 8, the reduced metal mixed in the electrolyte 17 is replaced. You may collect.

That is, the electrolytic solution 17 containing the conductive metal 11a removed from the base material 12 is collected in the recovery tank 23, and the microbubbles are mixed by the microbubble generator 24. As a result, the microbubbles become nuclei and the metal particles are clustered to be recovered by the filter, so that the reduced metal is recovered through the filter 25.

As described above, the present invention is not an electrolytic elution removal reaction in which a positive voltage is applied to a workpiece, which is generally performed, but a characteristic processing method of applying a negative voltage to the workpiece.

In addition, the electrolytic reaction here is because when causing the generation of H ₂ in the region of a very small amount of a conductive metal oxide thin film surface current is not almost needed.

Therefore, the electrolyte 17 used may be a mixture of a neutral salt solution generally used, or a neutral salt solution in tap water or river water, but preferably has a resistivity of 10 ² Ω · cm to 10 ⁶ Ω · cm More preferably, it is adjusted to 10 <^3> ohm * cm-10 <^4> ohm * cm. In the present invention, since both the first electrode 18 and the second electrode 13 are non-contact with the substrate 12, the first electrode 18 is high in the electrolytic solution 17 having a high resistivity of less than 10 ² Ω · cm. And a conductive state in which a voltage applied between the second electrode 13 does not pass through the conductive metal oxide thin film 11 and passes through the electrolyte 17 between the first electrode 18 and the second electrode 13. This is because the removal efficiency of the conductive metal oxide thin film 11 is lowered. If the resistivity exceeds 10 ⁶ Ω · cm, it is necessary to apply a high voltage, which is not economically desirable.

Thus, in this invention, since the electrolyte solution 17 with a comparatively high resistivity is suitable, the tap water, river water, etc. which were conventionally not preferable as electrolyte solution 17 can be used, and it is excellent also in the aspect of economy and safety.

Incidentally, a 100 mm x 100 mm workpiece formed of ITO having a film thickness of 1000 x 10 ^-10 m on a glass substrate using tap water as an electrolyte solution is immersed in the electrolyte solution as shown in Fig. 3, and immersed in the electrolyte solution as well. A DC voltage of about 100 V was applied to the second Cu electrode (anode) and the flat plate-shaped first electrode (cathode) for about 1 minute (current: 0.5 A), after which the glass substrate was made of a rotating sponge having a diameter of 150 mm. As a result of rubbing and wiping the surface of ITO, ITO can be removed and the glass substrate can be regenerated.

This invention is not limited to the above-mentioned example, For example, the technical idea of each claim, such as making the 2nd electrode 13 the inclined flat plate shape instead of the 1st electrode 18 of FIG. It goes without saying that the embodiment may be changed as appropriate within the scope of. In addition, recovery of the reduced metal mixed in the electrolyte solution 17 is not necessarily limited to the method shown in FIG.

Claims (5)

A substrate having a conductive metal oxide thin film immersed in an electrolyte solution; A first electrode immersed in an electrolyte solution; And A second electrode immersed in an electrolyte solution and disposed to face the conductive metal oxide thin film; And removing the conductive metal oxide thin film by a reduction reaction by applying a voltage such that the first electrode is a cathode and the second electrode is an anode. The method of removing a conductive metal oxide thin film according to claim 1, wherein the resistivity of the electrolyte is 10 ² Ω · cm to 10 ⁶ Ω · cm. An apparatus for carrying out the method of removing the conductive metal oxide thin film according to claim 1 or 2, comprising: A first electrode disposed to immerse at least one end in the electrolyte; A second electrode disposed so that at least one end is immersed in the electrolyte solution so that the conductive metal oxide thin film of the substrate immersed in the electrolyte solution in the processing tank becomes the cathode, and the one end is opposed to the conductive metal oxide thin film; And And a power supply for applying a voltage such that the second electrode is an anode and the first electrode is a cathode. The method of claim 3, wherein the first electrode or the second electrode is formed in a flat plate shape inclined in a non-contact state with the electrolyte above the substrate so that the electrolyte flows on the conductive metal oxide thin film of the substrate; An electrolytic solution supply mechanism for supplying an electrolytic solution to the inclined flat plate-shaped first electrode or the second electrode is provided. The apparatus for removing a conductive metal oxide thin film according to claim 3 or 4, further comprising a moving mechanism of the base or the second electrode, or a moving mechanism of the base and the second electrode.

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