JPH11106957A - Measuring method of hydrogen peroxide concentration in pre-etching liquid and controlling method of hydrogen peroxide concentration - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately measure the concn. of hydrogen peroxide in a pre- etching liquid without inhibition of metal ions dissolving in the liquid by adding an ammonium vanadate soln. with sulfuric acidity as a color developing reagent to color the pre-etching soln. and then measuring the absorbance in a specified wavelength range. SOLUTION: The absorbance of a colored polishing liquid is measured with a color meter at a proper wavelength in 420 to 490 nm wavelength range. Thereby, when quantitative measurement of absorbance is carried out by using the color developing reaction of hydrogen peroxide and ammonium vanadate, measurement of absorbance is not influenced by metal ions dissolving in the pre- etching soln. and the metal ions are not inhibiting factors for the measurement of hydrogen peroxide as far as the concn. of Fe4<3+> is 200 to 400 ppm or lower, Ni<2+> is 100 to 200 ppm or lower and Cr<3+> is 50 to 100 ppm or lower. When the concn. of oxalic acid or its dihydrate is 10 to 30 g/l, the changes in the measured value are suppressed within +2.5%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an etching product such as a shadow mask for a color picture tube, an aperture grill for a Trinitron (registered trademark) tube, and a lead frame for a semiconductor device by using a photo-etching method. Prior to the etching step of etching the exposed metal surface of the metal thin plate on which the resist film having the predetermined pattern is formed on the main surface, the oxide film or the resist remaining film formed on the surface to be etched of the metal thin plate is etched. In the surfacing (pre-etching) step of removing from the surface, the concentration of hydrogen peroxide contained in the surfacing liquid contained in the surfacing tank and into which the metal sheet is immersed is measured. The concentration of hydrogen peroxide in the surfacing liquid The measuring method and the concentration of hydrogen peroxide in the surface liquid in the surface tank are adjusted to a predetermined concentration. On the hydrogen peroxide concentration control method of the surface-out solution.

[0002]

2. Description of the Related Art Etching products such as shadow masks, aperture grills, and lead frames use photoetching to process long metal sheets such as low-carbon aluminum-killed steel and invar materials that are iron-nickel alloys. It is manufactured by In the etching process of the series of manufacturing processes of the etching product, the surface of the metal sheet is exposed before performing the spray etching. In this surface treatment, the oxide film adhering to the etched surface (exposed metal surface) of the thin metal plate after the development and hardening treatment, and the very thin remaining resist film that covers the etched surface are covered. This is performed for the purpose of removing from the etched surface. Then, in the surfacing step, a process of immersing the metal sheet in a surfacing liquid stored in a surfacing tank while carrying the long metal sheet in the longitudinal direction is performed. The surfacing liquid used in this surfacing step is an aqueous solution containing hydrogen peroxide, oxalic acid, sulfuric acid, etc. in industrial water, of which hydrogen peroxide is the surface to be etched of the metal sheet to be etched. In order to remove the remaining resist film adhering to the surface to be etched, the resist is contained in the surfacing liquid.

[0003] In the above-mentioned surfacing step, the concentration of hydrogen peroxide in the surfacing liquid gradually decreases as the metal sheet is treated. Therefore, in order to maintain the performance of the exposing liquid in a constant state, the exposing liquid is managed so that the hydrogen peroxide concentration in the exposing liquid is maintained at a predetermined concentration. The management of the surface liquid is performed by collecting a predetermined amount of the surface liquid contained in the surface tank from the surface tank, measuring the concentration of hydrogen peroxide contained in the collected surface liquid, Based on the measurement result, the replenishing amount of the hydrogen peroxide solution of the fresh surface liquid to the surface tank is controlled. The measurement of the concentration of hydrogen peroxide contained in the sampled surface liquor has been conventionally performed by an iodine coulometric titration method. The measurement of the concentration of hydrogen peroxide in the surface liquor by the iodine coulometric titration method is performed as follows. That is, a surface laying solution is added to an electrolytic solution containing sodium thiosulfate and potassium iodide. At this time, hydrogen peroxide in the surface oxidizing solution oxidizes potassium iodide in the electrolytic solution to generate iodine, and this iodine immediately reacts with a known amount of sodium thiosulfate contained in the electrolytic solution. Therefore, at this time, sodium thiosulfate is consumed in proportion to the concentration of hydrogen peroxide in the surface liquid. Therefore, the remaining sodium thiosulfate is subjected to coulometric titration (back titration) with iodine generated by electrolytic oxidation to measure the concentration of hydrogen peroxide in the exposed liquid.

[0004]

However, according to the conventional iodine coulometric titration method, the iron ions dissolved in the surfacing liquid hinder the measurement, and the measured hydrogen peroxide concentration actually decreases. Will cause an error with respect to the concentration of hydrogen peroxide. Conventionally, this measurement error has not been a serious problem in the management of the surface liquid. However, as etching products such as shadow masks have become more precise, errors in measuring the concentration of hydrogen peroxide in the surfacing liquid have become a problem in managing the surfacing liquid, and are more accurate than conventional methods. There is a need for a method capable of measuring the concentration of hydrogen peroxide in the exposed liquid. Furthermore, in recent years, as a material for a shadow mask, an invar material mainly composed of iron and nickel has been used, and accordingly,
Nickel ions in addition to iron ions are dissolved in the surface liquid, and the interference of the nickel ions causes a larger measurement error of the hydrogen peroxide concentration. Therefore, even when the invar material is used as a material for an etching product, a method is required that can accurately measure the concentration of hydrogen peroxide in the surface laying liquid.

[0005] The present invention has been made in view of the above-mentioned circumstances, and has been developed in such a manner that it is not hindered by metal ions such as iron ions and nickel ions dissolved in the surface liquid. To provide a method for measuring the concentration of hydrogen peroxide in a surface liquor that can accurately measure the concentration of hydrogen peroxide in the surface liquor, and to accurately measure the concentration of hydrogen peroxide in the surface liquor, It is an object of the present invention to provide a method for managing the concentration of hydrogen peroxide in a surfacing liquid which can accurately control the surfacing liquid in a surfacing tank.

[0006]

The invention according to claim 1 is
The etching process is performed prior to the etching step of etching the exposed metal surface of the metal sheet on which the resist film having the predetermined pattern is formed on the main surface, and the oxide film and the resist remaining film formed on the etched surface of the metal sheet are etched. In the method for measuring the concentration of hydrogen peroxide contained in the surfacing liquid used in the surfacing step used in the surfacing step of removing from the surface, a predetermined amount of the surfacing liquid is sampled,
After adding a sulfuric acid-acid ammonium vanadate solution as a coloring reagent to the collected surface-exposing solution to develop the surface-exposing solution, the wavelength of the color surface-exposing solution is 420 nm to 490 nm.
The method is characterized in that the absorbance at a predetermined wavelength in the range of nm is measured to determine the concentration of hydrogen peroxide in the surface laying liquid.

According to a second aspect of the present invention, an etching process is performed prior to an etching step of etching an exposed metal surface of a thin metal plate having a resist film having a predetermined pattern formed on a main surface thereof. In the surfacing step of removing the exposed oxide film and resist residual film from the surface to be etched, a predetermined amount of surfacing liquid that is contained in the surfacing tank and in which the metal sheet is immersed is collected from the surfacing tank and collected. Measuring the concentration of hydrogen peroxide contained in the quenching liquid, and controlling the replenishment amount of fresh clarifying liquid or hydrogen peroxide solution to the quenching tank based on the measurement result; In the method for controlling the concentration of hydrogen peroxide in the exposed liquid, which is adjusted so that the concentration of hydrogen peroxide in the exposed liquid in the liquid is maintained at a predetermined concentration, the concentration of hydrogen peroxide in the exposed liquid is measured as follows. To do The features. That is, after a predetermined amount of the surfacing liquid is collected from the surfacing tank, a sulfuric acid ammonium vanadate solution is added as a coloring reagent to cause the surfacing liquid to develop color. Wavelength 4
The absorbance at a predetermined wavelength in the range of 20 nm to 490 nm is measured to determine the concentration of hydrogen peroxide in the surface liquid.

When measuring the concentration of hydrogen peroxide in the surface liquor by the method according to the first aspect of the present invention, the concentration of the metal ions dissolved in the surface liquor is changed to iron ion (Fe ₃₊ ).
200 to 400 ppm or less, nickel ion (Ni ₂₊ ) is 100 to 200 ppm or less, and chromium ion (Cr ₃₊ ) is 50 to 100 ppm or less, which affects the absorbance measurement of the color surface exposure liquid. Without
It does not interfere with the measurement of hydrogen peroxide concentration. In addition, although oxalic acid contained in the surface liquid hinders the measurement, the oxalic acid dihydrate concentration is 10 to 30 g / L (20 g / L ± 10 g / L).
In the case of L), the fluctuation of the measured value falls within ± 2.5%. Therefore, according to this method, the concentration of hydrogen peroxide in the surface liquid can be accurately measured.

When the concentration of hydrogen peroxide in the surface liquid is controlled by the method according to the second aspect of the present invention, the concentration of hydrogen peroxide in the surface liquid can be accurately measured as described above. Therefore, the replenishing amount of the fresh surfacing liquid or the hydrogen peroxide solution to the surfacing tank is controlled based on the measurement result, so that the hydrogen peroxide concentration in the surfacing liquid in the surfacing tank becomes a predetermined concentration. , And the management of the surface liquid in the surface tank is performed with high accuracy.

[0010]

Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of application of a method for managing the concentration of hydrogen peroxide in a surface liquid using the method for measuring the concentration of hydrogen peroxide in a surface liquid according to the present invention. FIG. 2 is a schematic diagram partially showing a block diagram. The management of the surface liquid in the surface tank in the surface step is performed with respect to the temperature of the surface liquid, the oxidation-reduction potential, and the like, but in this specification, the management of the hydrogen peroxide concentration in the surface liquid is performed. And only the relevant elements are shown in FIG.

A metal thin plate having a resist film having a predetermined pattern formed on a main surface thereof after completion of development and hardening treatment in a previous step, for example, a long metal thin plate 10 made of Invar material is continuously conveyed and exposed. When the metal sheet 10 is carried into the apparatus 12, the metal sheet 10 is transported by a plurality of transport rollers 14.
The surfacing liquid 16 is guided into the surfacing tank 18 in which the surfacing liquid 16 is stored, immersed in the surfacing liquid 16 in the surfacing tank 18, and then sent out of the surfacing tank 18 and transported to an etching chamber (not shown). It is supposed to be. The surfacing liquid 16 may have the same composition as that conventionally used, but one example of the composition is as follows. For 100 L of industrial water, 1.5 kg of 35% hydrogen peroxide water is used. , 2.0 kg of oxalic acid and 40 ml of 96% sulfuric acid. Further, the temperature of the surfacing liquid 16 is, for example, 20 ° C. to 30 ° C.
Adjusted to ° C.

The concentration control device for controlling the concentration of hydrogen peroxide in the surface liquid 16 in the surface bath 18 includes a concentration measuring unit 20 for measuring the concentration of hydrogen peroxide in the surface liquid, A liquid circulation pump 22 which collects the exposed liquid 16 from the inside and sends it to the concentration measuring unit 20, a control unit (system control sequencer) 24 for controlling the whole system, and a cycle for measuring the concentration of hydrogen peroxide in the exposed liquid 16 Measurement period operation unit (measurement period timer) 26 for setting the setting, and the conversion unit 2 for outputting a control signal corresponding to the hydrogen peroxide concentration measured by the concentration measurement unit 20
8. Receiving a control signal from the surfacing liquid tank 30 storing the fresh surfacing liquid and the conversion unit 28, and replenishing the surfacing liquid stored in the surfacing liquid tank 30 to the surfacing tank 18 by a required amount. It is composed of a liquid supply pump 32 and the like.

As shown in the block diagram of FIG. 2, the concentration measuring section 20 includes an overflow tank 34 for temporarily storing the overflow liquid fed from the inside of the exposure liquid tank 30 while overflowing the overflow liquid, and a predetermined amount from the overflow tank 34. A measuring unit 36 for measuring and dispensing a predetermined amount of the exposing liquid, adding a predetermined amount of a coloring reagent to the predetermined amount of the exposing liquid, and mixing the same, and measuring the absorbance of the exposing liquid mixed with the coloring reagent to form a color. A colorimeter 38 that outputs a voltage proportional to the absorbance, and a display device that calculates the concentration of hydrogen peroxide in the exposed liquid from the absorbance output from the colorimeter 38, and displays and records the concentration. It is provided with an attached recorder 40. The surface liquid overflowing from the overflow tank 34 is returned to the surface tank 18. The surface liquid is circulated between the surface tank 16 and the overflow tank 34 of the concentration measuring unit 20. Can be Also, the measuring section 3
6, the colorimeter 38 and the recorder 40 with a display
4 is controlled collectively. Further, the recorder 40 with a display is connected to the conversion unit 28, and the conversion unit 28
From the amount of deviation between the measured concentration of hydrogen peroxide sent from the recorder 40 with the indicator of the concentration measuring unit 20 and the preset target concentration of hydrogen peroxide, based on the control parameter input in advance, The number of times the liquid supply pump 32 is driven is calculated so that the concentration of hydrogen peroxide in the surfacing liquid 16 in the surfacing tank 18 becomes the target concentration, and a control signal is output.

As shown in the flow path diagram in FIG. 3, the measuring section 36 includes an eight-way cock 42, a syringe 44, a measuring pipe 46, a coloring reagent tank 48, a pure water tank 50, a pure water supply pump 52, and a magnetic stirrer. Mixing cell 54, three-way switching valve 5
6 and a sampling and waste liquid pump 58 are provided. Then, the overflow tank 34, the syringe 44, both ends of the measuring tube 46, the coloring reagent tank 48, the pure water tank 5
0, a mixing cell 54 and a three-way switching valve 56 are connected to the eight ports of the eight-way cock 42 respectively. The outlet of the mixing cell 54 is connected to the inlet of a flow cell (not shown) of the colorimeter 38, and the outlet of the flow cell of the colorimeter 38 is connected to the three-way switching valve 56. The coloring reagent tank 48 contains a sulfuric acid acidic ammonium vanadate solution.

Next, a description will be given of an operation of maintaining and controlling the concentration of hydrogen peroxide in the surfacing liquid 16 in the surfacing tank 18 during the surfacing process by the concentration management device having the above-described configuration.

First, the operation of measuring the concentration of hydrogen peroxide in the surfacing liquid 16 in the surfacing tank 18 will be described. The surfacing liquid 16 in the surfacing tank 18 is collected by a predetermined amount and sent to the overflow tank 34 of the concentration measuring unit 20 by the liquid circulation pump 22. The flush liquid temporarily stored in the overflow tank 34 is supplied to the three-way switching valve 56 by the sampling / waste liquid pump 58 in a state where the eight-way cock 42 of the measuring section 36 is switched to the position shown in FIG. , The liquid is introduced into the measuring pipe 46, and a predetermined amount of the exposed liquid is collected in the measuring pipe 46. The amount of the face-out liquid collected in the measuring tube 46 is, for example, a fixed amount of 0.5 ml to 1 ml. At this time, the syringe 44 is driven at the same time, and the coloring reagent tank 4 is moved.
From 8 to a certain amount of ammonium vanadate solution is drawn into the syringe 44. In this case, the amount of the ammonium vanadate solution to be added to the exposing liquid should be such that the coloring agent, ammonium vanadate, is within about 4 times the molar concentration ratio of hydrogen peroxide in the exposing liquid. The sulfuric acid concentration of the ammonium vanadate solution is adjusted to about 1 molar. Further, the pure water supply pump 52 is driven to supply pure water from the pure water tank 50 into the mixing cell 54 and the flow cell of the colorimeter 38, and the inside of the mixing cell 54 and the colorimeter 3
The inside of the flow cell of No. 8 is washed with pure water. The waste liquid after washing is discharged by a pump 58 through a three-way switching valve 56. After the completion of the cleaning operation, a certain amount of pure water is injected and stored in the mixing cell 54.

When a predetermined amount of face-out liquid is dispensed into the measuring tube 46 and a certain amount of ammonium vanadate solution is sucked into the syringe 44, the eight-way cock 42 is moved to the position shown in FIG. Can be switched. In this state, the syringe 44
Is driven, a predetermined amount of ammonium vanadate solution is extruded from the inside of the syringe 44, and the exposed liquid in the measuring tube 46 flows into the mixing cell 54 together with the predetermined amount of ammonium vanadate solution. Then, in the mixing cell 54, the pure water, the surfacing liquid and the ammonium vanadate solution are stirred and diluted and mixed by a magnetic stirrer. By this operation, the surface-exposing liquid develops a color, and the color-exposed liquid flows from the mixing cell 54 into the flow cell of the colorimeter 38, and the color-exposed liquid flows while passing through the flow cell. The absorbance of the coloring surface liquid is measured by a meter.

Here, the ammonium vanadate solution is yellow, and due to the reaction between hydrogen peroxide and ammonium vanadate in the exposing liquid, the liquid in which the exposing liquid and the ammonium vanadate solution are mixed develops a color. It has a reddish-brown color.
The maximum absorption wavelength in the visible region of the color surface liquid is, for example, 455 nm. When oxalic acid is present in the surface liquid, the maximum absorption wavelength shifts from 447 nm to 450 nm. Therefore, the measurement of the absorbance of the coloring surface liquid by the colorimeter 38 is performed at an appropriate wavelength within the range of 420 nm to 490 nm.

As described above, according to the method of measuring the concentration of hydrogen peroxide in the surface liquor by absorptiometry using the color reaction between hydrogen peroxide and ammonium vanadate, The concentration of metal ions is 200 to 400 ppm or less for iron ions (Fe ₃₊ ) and 100 to 200 ppm for nickel ions (Ni ₂₊ ).
Hereinafter, chromium ions (Cr ₃₊ ) are 50 to 100.
If it is at most ppm, it will not affect the absorbance measurement of the color surface exposure liquid and will not be an obstacle to the hydrogen peroxide concentration measurement. In addition, although oxalic acid contained in the surface liquid hinders the measurement, the oxalic acid dihydrate concentration is 10 to 30 g / L (20 g / L).
(± 10 g / L), the fluctuation of the measured value falls within ± 2.5%. Furthermore, even if citric acid is contained in the exposing liquid, citric acid does not affect the color reaction of the exposing liquid, and even if 3 ml of concentrated hydrochloric acid is contained in 1 liter of the exposing liquid. In addition, hydrochloric acid does not affect the color reaction of the exposed solution.

The absorbance of the color surface liquid is measured by the colorimeter 38, and when a voltage proportional to the absorbance is output from the colorimeter 38 and input to the recorder 40 with an indicator, the recording with an indicator is performed. In the total 40, the concentration of hydrogen peroxide in the surface liquid is calculated from the absorbance output from the colorimeter 38 based on the data of the calibration curve prepared and input in advance. Then, the calculated hydrogen peroxide concentration in the surfacing liquid is displayed and recorded on the recorder 40 with a display.

The operation of measuring the concentration of hydrogen peroxide in the surfacing liquid 16 in the surfacing tank 18 is performed as described above.
The measurement of the concentration of hydrogen peroxide in the surface liquid 16 is performed at a measurement cycle set by the measurement cycle operation unit 26, for example, 10 minutes to 1 minute.
It is performed intermittently with a period of 5 minutes. And the concentration measuring unit 2
When the measured concentration of hydrogen peroxide intermittently sent from the recorder 40 with a display of 0 to the conversion unit 28 deviates from the preset target concentration of hydrogen peroxide, the conversion unit 28 immediately outputs the target concentration. The required control signal is output and the feed pump 32
Is controlled, and the required amount of fresh surface liquid is replenished from the surface liquid tank 30 to the surface tank 18. This allows
The concentration of hydrogen peroxide in the surface liquid 16 in the surface bath 18 is as follows:
It will always be maintained at the predetermined concentration.

The facing liquid tank 30 in the above-described embodiment.
Instead, a hydrogen peroxide solution tank storing hydrogen peroxide solution is provided, and a required amount of the hydrogen peroxide solution stored in the hydrogen peroxide solution tank is controlled by a liquid supply pump 32 controlled by a control signal from the conversion unit 28. Only the surface tank 30 may be replenished.

[0024]

According to the method for measuring the concentration of hydrogen peroxide in a surface liquor according to the first aspect of the present invention, metal ions such as iron ions and nickel ions dissolved in the surface liquor are free from interference. The present invention can accurately measure the concentration of hydrogen peroxide in the surface liquid. The present invention meets the demand for improvement in measurement accuracy when used as a device.

According to the method for controlling the concentration of hydrogen peroxide in the surfacing liquid according to the second aspect of the present invention, the concentration of hydrogen peroxide in the surfacing liquid is accurately measured, so that the inside of the surfacing tank can be controlled in the surfacing step. The present invention is capable of accurately controlling the surface exposure liquid, and the present invention relates to a demand for improvement of the control accuracy accompanying the high definition of an etching product such as a shadow mask, and a management in a case where an invar material is used as a material of the etching product. It responds to requests for improved accuracy.

[Brief description of the drawings]

FIG. 1 shows an application example of a method for managing the concentration of hydrogen peroxide in a surface liquid using the method for measuring the concentration of hydrogen peroxide in a surface liquid according to the present invention. It is the schematic which shows a part with a block diagram.

FIG. 2 is a block diagram showing a configuration of a part of a device for managing the concentration of hydrogen peroxide in a surfacing liquid of the surfacing device shown in FIG. 1;

FIG. 3 is a flow path diagram of a concentration measuring section of the apparatus for managing the concentration of hydrogen peroxide in the surface liquid shown in FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Metal thin plate 12 Exposure apparatus 16 Exposure liquid 18 Exposure tank 20 Concentration measuring part 22 Liquid circulation pump 24 Control part (system control sequencer) 26 Measurement period operation part (measurement period timer) 28 Conversion part 30 Exposure liquid tank 32 Liquid supply pump 34 Overflow tank 36 Measuring unit 38 Colorimeter 40 Recorder with indicator 42 Hawk cock 44 Syringe 46 Measuring tube 48 Coloring reagent tank 50 Pure water tank 54 Mixing cell 58 Sampling and waste liquid pump

Claims (2)

[Claims] An oxide film or a resist formed on an etched surface of a metal thin plate, which is performed prior to an etching step of etching an exposed metal surface of the metal thin plate having a resist film having a predetermined pattern formed on a main surface thereof. In the method for measuring the concentration of hydrogen peroxide contained in a surfacing liquid used in a surfacing step for removing a residual film from a surface to be etched, a method for measuring the concentration of hydrogen peroxide in the surfacing liquid, a predetermined amount of the surfacing liquid Was collected, and a sulfuric acid ammonium vanadate solution was added as a color-forming reagent to the collected surface-exposing solution to develop the surface-exposing solution. A method for measuring the concentration of hydrogen peroxide in the exposed liquid by measuring the absorbance at a predetermined wavelength in the liquid. 2. An oxide film or a resist formed on a surface to be etched of a metal thin plate, which is performed prior to an etching step of etching an exposed metal surface of the metal thin plate having a resist film having a predetermined pattern formed on a main surface thereof. In the surfacing step of removing the remaining film from the surface to be etched, a surfacing liquid that is contained in the surfacing tank and in which the metal sheet is immersed is collected by a predetermined amount from the surfacing tank. The concentration of the contained hydrogen peroxide is measured, and the replenishing amount of fresh surfacing solution or hydrogen peroxide solution to the surfacing tank is controlled based on the measurement result, so that the Adjusting the concentration of hydrogen peroxide to be maintained at a predetermined concentration,
In the method for controlling the concentration of hydrogen peroxide in a surface exposure liquid, a sulfuric acid ammonium vanadate solution is added as a coloring reagent to the surface exposure liquid collected by a predetermined amount from the surface exposure tank to develop the surface exposure liquid. After that, the absorbance at a predetermined wavelength within the wavelength range of 420 nm to 490 nm of the color surface exposure liquid is measured to determine the concentration of hydrogen peroxide in the surface exposure liquid. Hydrogen peroxide concentration control method.