JPH06336683A - Method for regenerating etching solution and regenerating device therefor - Google Patents

Abstract

PURPOSE:To provide a method for regenerating an etching solution and a regenerating device for the method, with which the composition of the etching solution that enables good patterning can be maintained and the consumption of expensive hydroiodic acid can be reduced. CONSTITUTION:In the method for regenerating the etching solution which is used for forming a transparent electrode pattern on the surface of a substrate for the liquid crystal display element by the etching, the etching solution contg. at least a solution mixture consisting of hydroiodic acid and ferric chloride is replenished with hydrochloric acid and water. At this time, the replenishing amounts of hydrochloric acid and water are calculated by using the chlorine ion concentration and specific gravity values of the etching solution before and after the regeneration. The replenishment of the etching solution with hydrochloric acid and water is performed by mixing hydrochloric acid and water in a ratio calculated as described above and thereafter adding the resulting mixture to the etching solution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for regenerating an etching solution containing a mixture of hydroiodic acid and ferric chloride used for forming a transparent electrode pattern on the surface of a liquid crystal display substrate. Is.

[0002]

2. Description of the Related Art Conventionally, as an etching solution used for etching an ITO film formed on a substrate for a liquid crystal display element to form an ITO electrode fine pattern, for example, hydrochloric acid / ferric chloride mixed solution, A hydrochloric acid / nitric acid mixed solution is used. In these hydrochloric acid-based etching solutions, solution deterioration occurs such that it becomes difficult to control the pattern line width and maintain the etching rate due to changes in the composition of the solution accompanying the etching process.

In order to cope with the change in the composition of the etching solution, hydrochloric acid or water is replenished to maintain the etching solution in such a composition that a good patterning characteristic can be obtained. For the management of this etching solution, the oxidation-reduction potential and the specific gravity of the etching solution are measured, and water, hydrochloric acid and a reducing agent are generally replenished in order to keep them constant.

[0004]

[Problems to be Solved by the Invention] However, I
When the hydrochloric acid / ferric chloride mixed solution or the hydrochloric acid / nitric acid mixed solution shown in the above conventional example is used as the TO etching solution, the etching solution permeates the interface between the ITO and the photoresist to form an ITO pattern. Undercut is apt to occur, and it is not suitable for pattern miniaturization associated with higher definition of liquid crystal display devices. Furthermore, when an ITO pattern is formed on an organic film such as a color filter, the pattern edge is disturbed or peeling occurs at the interface between the organic film and the ITO for the same reason as described above, which makes pattern formation difficult.

On the other hand, when an etching solution composed of a mixture of hydroiodic acid and ferric chloride is used, the undercut of the ITO pattern is very small, which is suitable for miniaturization. ITO on organic film
An etching solution composed of a mixture of hydroiodic acid and ferric chloride is also used as an etching solution instead of a hydrochloric acid system because it has an advantage that pattern formation is possible. However, the following equilibrium reaction exists in this etching solution, and chlorine ions are generated.

[0006]

[Chemical 1]

Further, as a result of the mist containing chlorine ions being discharged out of the system due to the etching treatment, there is a drawback that the composition of the etching solution changes and the etching characteristics deteriorate.

The present invention has been made in order to solve the above-mentioned problems of the conventional example. By replenishing the etching solution with hydrochloric acid and water, the composition of the solution for maintaining good patterning is maintained. It is therefore an object of the present invention to provide a method and apparatus for regenerating an etching solution that can reduce the amount of expensive hydroiodic acid used.

[0009]

That is, the present invention provides a method of regenerating an etching solution used for forming a transparent electrode pattern on a surface of a liquid crystal display element substrate by etching, wherein at least the etching solution is hydroiodic acid. A method for regenerating an etching solution, which comprises supplementing hydrochloric acid and water to a mixed solution containing ferric chloride.

Further, according to the present invention, in an apparatus for regenerating an etching solution used for forming a transparent electrode pattern on a surface of a substrate for a liquid crystal display element by etching, a chlorine ion concentration and a specific gravity of the etching solution are constantly measured, An apparatus for regenerating an etching solution, comprising means for controlling the replenishment amounts of hydrochloric acid and water to the etching solution such that the ion concentration and the specific gravity are within a certain value.

The present invention will be described in detail below. In the method for regenerating an etching solution of the present invention, the replenishment amounts of hydrochloric acid and water are calculated from the chlorine ion concentration and specific gravity of the etching solution before and after the regeneration. Also, replenishing the etching solution with hydrochloric acid and water is
It is preferable to add hydrochloric acid and water at a ratio calculated by the above method and then add them to the etching solution.

Next, the grounds for calculating the replenishment amounts of hydrochloric acid and water in the etching liquid regenerating method of the present invention are shown below. The amount of etching solution at the time of deterioration is A (l), the specific gravity is d _A , the chlorine ion concentration is C _A (g / l), and the specific gravity at the time of regeneration is d
_B and chloride ion concentration C _B (g / l). The hydrochloric acid used for replenishment is a commercial product with a concentration of 35% and a specific gravity of 1.175.

Further, when the replenishing amount of hydrochloric acid is x (l) and the replenishing amount of water is y (l), the following relational expression is established.

[0014]

[Equation 1] Solving this for hydrochloric acid / water replenishment amounts x (l) and y (l),

[0015]

[Equation 2]

Therefore, the amount of etching liquid at the time of deterioration,
By measuring the specific gravity and chlorine ion concentration in advance and setting the specific gravity and chlorine ion concentration during regeneration to the specific gravity and chlorine ion concentration of the new liquid, the replenishment amount of hydrochloric acid and water can be calculated.
Then, by replenishing both of them with the deteriorated etching solution, it is possible to regenerate the same composition as the new solution.

Regarding the method of replenishing hydrochloric acid / water, when hydrochloric acid is directly added, a precipitate of a solid substance is not formed and is not regenerated. Therefore, the replenished portions of hydrochloric acid and water are mixed in advance, diluted and then replenished to the etching solution. Preferably.

[0018]

EXAMPLES The present invention will be specifically described below with reference to examples.

Example 1 FIG. 1 shows an example of a method for regenerating an etching solution according to the present invention, showing a flow of a regenerating apparatus in which a hydrochloric acid / water mixing tank for regenerating the etching solution is added to an ITO etching line. It is a thing.

In the ITO etching liquid tank 1, hydroiodic acid (58 wt%): ferric chloride (35 wt%) = 7: 3
A mixed liquid having a ratio of (Vol ratio) is stored and stirred by the etching liquid circulation pump 2. The concentration of the main components in the etching solution at the time of the new solution is 600 to 70 for all iodine ions.
0 g / l, total iron ions 40 to 60 g / l, and chlorine ions 80 to 100 g / l. The specific gravity is 1.5 to 1.6.
Is.

During the etching process, since the etching solution is heated and the etching method is a spray method, a mist containing chlorine is generated and exhausted to the outside of the system. As a result, the composition of the etching solution changes, and the main component concentrations are 1100 to 1200 g / l for all iodine ions and 9 for all iron ions.
It is concentrated to 0-110 g / l. On the other hand, chlorine ions are reduced to 0 to 5 g / l.

As the composition of the etching solution changes, IT
Since the side etch amount of the O pattern changed and the etching characteristics deteriorated, the ultrapure water 4 calculated by the formula in the hydrochloric acid / water mixing tank 3 was y (l), and the hydrochloric acid x calculated by the formula was x.
(1) was added, and the regenerant liquid was prepared by stirring with the regenerant liquid circulation pump 5. Then, through the regeneration liquid delivery pump 6,
The regenerating liquid was sent to the ITO etching liquid tank, and was stirred together with the etching liquid by the etching liquid circulation pump.

The etching solution whose composition has been changed by this etching solution regeneration method is composed of all iodine ions, all iron ions,
Any concentration of chlorine ions could be used as a regenerative etching solution equivalent to the new solution. Regarding the etching property, the number of electrode shorts was remarkably reduced by the regeneration, and an extremely good regenerated etching solution was obtained.

Embodiment 2 FIG. 2 shows another embodiment of the method for regenerating an etching solution according to the present invention, which is characterized by having a mixing device for controlling the mixed composition of hydrochloric acid and water and the replenishment amount according to the expressions. 3 shows a flow of the playback device.

The same etching solution as in Example 1 is stored in the ITO etching tank 1 and stirred by the etching solution circulating pump 2. A liquid lower limit sensor 7, a specific gravity monitor 8, and an ion electrode type chlorine ion concentration monitor 9 are attached to the ITO etching tank 1. When the etching liquid decreases due to the etching process and the liquid lower limit sensor 7 detects that the liquid is below the liquid lower limit, the specific gravity of the etching liquid at that time is detected by the specific gravity monitor 8, and the chlorine ion concentration of the etching liquid is determined by the ion electrode type chlorine ion concentration. It was made into a device so that the monitor 9 could measure. The liquid lower limit was set to 1/2 of the initial liquid amount.

Information on the liquid lower limit liquid amount and the specific gravity and the chlorine ion concentration measured by the above method is sent to the regeneration control device 10, and the replenishment amount x (l) of hydrochloric acid obtained from the formula is obtained.
A signal line is provided to send an instruction to the hydrochloric acid / water mixing tank 3 to the hydrochloric acid tank pump 11.

Further, a signal line for sending an instruction for supplying the replenishment amount y (l) of water to the hydrochloric acid / water mixing tank 3 to the ultrapure water solenoid valve 12 is provided. The hydrochloric acid tank 13 was provided with a pipe for storing 35% hydrochloric acid and capable of sending the hydrochloric acid to the hydrochloric acid / water mixing tank 3 by the hydrochloric acid tank pump 11. In the hydrochloric acid / water mixing tank 3 to which the replenishment amounts x (l) and y (l) of the hydrochloric acid / water were supplied according to the instructions of the above-mentioned regeneration control device, the liquid is uniformly distributed by the regenerant circulation pump 5 as in the first embodiment. Stirring was carried out until. The regenerant liquid thus prepared was supplied to the ITO etching tank 1 by the regenerant liquid feed pump 6 and agitated by the liquid circulation pump.

By using the above-mentioned regeneration system having a mixing device for controlling the mixed composition of hydrochloric acid and water-replenishment amount, the deteriorated etching solution is automatically regenerated and a stable etching solution treatment capacity is provided. In addition, the amount of new liquid input and the amount of waste liquid generated have been significantly reduced.

[0029]

As described above, according to the present invention, hydrochloric acid and ultrapure water are used against the deterioration caused by the etching process of the ITO etching solution which is a mixed solution of hydroiodic acid and ferric chloride. By replenishing the mixed solution, the deteriorated etching solution has the same processing capacity as the new solution, and the ITO etching process can be stabilized. In addition, instead of introducing a new liquid of expensive hydriodic acid / ferric chloride mixture, it is possible to drastically reduce the cost by introducing inexpensive hydrochloric acid / ultra pure water mixed liquid.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a flow of a reproducing apparatus in which a hydrochloric acid / water mixing tank for reproducing an etching solution is added to an ITO etching line according to the present invention.

FIG. 2 is an explanatory diagram showing a flow of a regenerator in which a mixing device for controlling a mixed composition of hydrochloric acid and water and a replenishment amount is added to the ITO etching line according to the present invention.

[Explanation of symbols]

 1 ITO etching tank 2 Etching liquid circulation pump 3 Hydrochloric acid / water mixing tank 4 Ultrapure water 5 Regeneration liquid circulation pump 6 Regeneration liquid feed pump 7 Liquid lower limit sensor 8 Specific gravity monitor 9 Ion electrode type chloride ion concentration monitor 10 Regeneration control device 11 Hydrochloric acid tank pump 12 Ultrapure water solenoid valve 13 Hydrochloric acid tank

Claims (4)

[Claims] 1. A method of regenerating an etching solution used for forming a transparent electrode pattern on a surface of a substrate for a liquid crystal display element by etching, wherein at least the etching solution is a mixed solution of hydroiodic acid and ferric chloride. A method for regenerating an etching solution, which comprises supplementing hydrochloric acid and water. 2. The method of regenerating the etching solution,
The method for regenerating an etching solution according to claim 1, wherein the replenishment amounts of hydrochloric acid and water are calculated from the chlorine ion concentration and specific gravity of the etching solution. 3. The method for regenerating an etching solution according to claim 1, wherein hydrochloric acid and water are added to the etching solution after mixing the hydrochloric acid and water at a ratio calculated according to claim 2. 4. A chlorine ion concentration and a specific gravity of the etching solution are constantly measured in an apparatus for regenerating an etching solution used for forming a transparent electrode pattern on a surface of a substrate for a liquid crystal display element by etching. An apparatus for regenerating an etching solution, comprising means for controlling the replenishment amounts of hydrochloric acid and water to the etching solution such that