JP2005187844A - Device and method for regenerating acid solution and measuring concentration - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simply perform the regeneration of acid solution and to make measurable of acid concentration in the acid solution and the concentration of eluted material. <P>SOLUTION: In an acid solution regenerating system, the acid solution is held into a vessel and regarding this acid solution, both of the concentration of the acid and the concentration of material eluted in the acid solution are decided. Further, a tank for holding the original liquid of the acid solution, a supplying device for supplying the original liquid from the tank into a vessel and a discharging device for discharging the acid solution from the tank, are arranged, and based on the obtained concentration from a concentration measuring instrument, the original liquid of the acid solution is supplied from the tank with the supplying device and the acid solution in the vessel is discharged with the discharging device, and the acid concentration in the acid solution in the vessel is controlled. Desirably, further, the acid solution is introduced from the vessel into a removing device and the eluted material in the introduced acid solution is removed and the acid solution removing the eluted material is returned back to the vessel. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to concentration measurement, concentration control and regeneration of an acid solution used for etching and the like.

  Acid solutions are used to dissolve various substances. For example, in the etching of various materials such as metals such as copper, aluminum, silicon, and steel, and semiconductors, acid solutions (chemicals) such as hydrochloric acid overwater, aqua regia, phosphoric acid nitrate acetic acid, and ferric chloride are used. In order to manage processes such as etching, it is necessary to know the concentration of the acid solution and the concentration of the eluted material. Therefore, the concentration of the acid and the eluted substance in the acid solution is measured.

  Various methods are used to measure the concentration of the acid and the eluted substance in the acid solution. In the method for measuring the acid concentration in the etching solution described in JP-A-6-265471, spectroscopic measurement is used. In addition, atomic absorption analysis, ion chromatography, ICP analysis, and the like have been used to measure the concentration of metal eluted in the etching solution. For example, in the analysis method described in Japanese Patent Laid-Open No. 10-227742, the copper concentration of the ferric chloride etching solution is obtained by diluting the sample by atomic absorption spectrometry. In JP-A-7-176853, in an ITO thin film etching solution, the acid concentration is measured by electrical conductivity, and the indium content is determined using an absorptiometer.

  The acid solution can be regenerated by adding various chemicals to control the concentration. For example, in the control method described in Japanese Patent Application Laid-Open No. 10-280171, the pH of a ferric chloride etching solution is adjusted by adding an acidic solution based on the measured pH value.

Further, by removing the metal eluted in the etching solution, the etching solution can be regenerated and the etching rate can be controlled to be constant. As a method for regenerating the etching solution, there are a method of taking out as a metal salt by heating or cooling, a method of taking out metal ions by an electrolytic method, and the like. In the reproduction, the concentration of the etching solution and the amount of the substance (containing material in the etching solution) dissolved in the etching solution are monitored, and the dissolved material is removed when the amount of dissolution increases. For example, in the measurement of the aluminum content of an aluminum etching solution described in Japanese Patent Application Laid-Open No. 11-14606, the aluminum content is calculated by measuring the speed of sound. Concentration and aluminum content are kept constant. In the regeneration method described in JP-A-11-140673, the etching solution is regenerated by extracting and removing copper from the waste solution by solvent extraction in a sulfuric acid / hydrogen peroxide-based copper etching solution or the like.
JP-A-6-265471 JP-A-10-227742 Japanese Patent Laid-Open No. 7-176853 Japanese Patent Laid-Open No. 10-280171 Japanese Patent Laid-Open No. 11-14606 JP-A-11-140673 JP-A-8-199480 JP 2002-20959 A

  Conventionally, atomic absorption analysis, ion chromatography, ICP analysis, etc. have been used as a method for measuring the concentration of contained metals in an acid solution such as an etchant, but these require dilution or combustion for measurement. Therefore, it is not suitable for in-line measurement, and it is difficult to incorporate it into the manufacturing process. In addition, the management of stabilizing the etching rate requires both the acid concentration of the etching solution and the concentration of the dissolved metal, etc., but the conventional measurement method cannot simultaneously measure the concentration of the etching solution. For this reason, process control with a constant etching rate could not be performed. Also, conventional equipment for regenerating acid solutions uses a method of extracting metal salts and metal ions, which is very large and expensive.

An object of the present invention is to easily regenerate an acid solution.
Another object of the present invention is to make it possible to measure both the acid concentration of the acid solution and the concentration of the eluted substance.

  An acid solution regeneration system according to the present invention includes a tank that stores an acid solution, a concentration measuring device that determines both the concentration of an acid and the concentration of a substance eluted in the acid solution, and an acid solution Based on the concentration obtained by the tank that contains the stock solution, the supply device that supplies the stock solution from the tank to the tank, the discharge device that discharges the acid solution from the water tank, and the concentration measurement device, the supply device supplies the acid solution from the tank. A concentration controller for supplying the stock solution, discharging the acid solution in the tank by the discharge device, and controlling the concentration of the acid in the acid solution in the tank;

  In the acid solution regeneration system described above, the stock solution in the tank is, for example, a new acid solution, a composition chemical solution and pure water contained therein.

  In the acid solution regeneration system, for example, the concentration control device receives concentration data from the concentration measuring device, calculates a supply amount and a discharge amount, and controls the supply device and the discharge device.

  Preferably, the acid solution regeneration system further includes a removing device that introduces the acid solution from the tank, removes the eluted substance in the introduced acid solution, and returns the acid solution from which the eluted substance has been removed to the tank. Prepare. Preferably, the removal device includes a filter that has been subjected to a plasma graft polymerization process to adsorb specific metal ions, for example. In addition, preferably, a bypass line is further provided in parallel with the removal device.

  In the acid solution regeneration system, the concentration measuring device is, for example, a spectroscopic measuring device. The spectroscopic measurement apparatus includes a light transmission or reflection detection cell into which an acid solution sample to be measured is introduced, a light source that irradiates the cell with light having a wavelength within the wavelength range of ultraviolet light, visible light, and near infrared light. , A spectroscopic means for splitting transmitted light or reflected light obtained by irradiating the light from the light source to the cell, and receiving the light dispersed by the spectroscopic means, and generating a light intensity signal corresponding to the intensity of the received light Absorbance is calculated from the light receiving means, the storage means for storing the calibration curve formula indicating the relationship between the concentration of the acid in the acid solution and the concentration of the substance eluted in the acid solution and the absorbance, and the light intensity signal input from the light receiving means. And the concentration calculation means for simultaneously determining the concentration of the acid in the acid solution and the concentration of the substance eluted in the acid solution from the absorbance based on the calibration curve equation. Preferably, a cell of the spectroscopic measurement device is disposed in the acid solution path between the tank and the removal device. As a result, the removal device can be installed in a closed loop of the circulation line for measuring the concentration, and the regeneration of the acid solution can be performed in parallel with the concentration measurement.

  In the acid solution regeneration system, the concentration measuring device is, for example, a spectroscopic measurement probe that is immersed in the tank and performs concentration measurement.

  The concentration measuring apparatus according to the present invention irradiates a cell for light transmission or reflection detection into which an acid solution sample to be measured is introduced, and light in an ultraviolet wavelength region, a visible light wavelength region, and a near-infrared wavelength region. A light source, a spectroscopic means for dispersing transmitted light or reflected light obtained by irradiating light from the light source to the cell, light received by the spectroscopic means, and a light intensity signal corresponding to the intensity of the received light The light receiving means to be generated, the storage means for storing the calibration curve formula indicating the relationship between the concentration of the acid in the acid solution and the concentration of the substance eluted in the acid solution and the absorbance, and the absorbance from the light intensity signal input from the light receiving means And concentration calculating means for simultaneously determining the concentration of the acid in the acid solution and the concentration of the substance eluted in the acid solution from the absorbance based on the calibration curve equation. The light in the ultraviolet wavelength range, visible wavelength range, and near infrared wavelength range is, for example, 190 to 2000 nm. In one example, the wavelength range is 350 to 2000 nm. The absorbance is measured at several points to several tens of points, for example, discretely within this wavelength range. Or it measures using the continuous spectrum in this wavelength range.

  In the concentration measurement method according to the present invention, the concentration of the acid in the acid solution and the substance eluted in the acid solution are measured. Here, for the acid solution sample to be measured, the intensity of the transmitted or reflected light with a wavelength within the wavelength range of ultraviolet light, visible light and near infrared light is measured, and then the absorbance is calculated from the light intensity signal. Then, both the concentration of the acid in the acid solution and the concentration of the substance eluted in the acid solution are calculated from the absorbance based on the calibration curve equation obtained in advance.

  A concentration control device is provided to control the concentration of the acid solution in response to the concentration measurement result from the concentration measuring device. Since the acid and substance concentrations can be determined simultaneously, the etching process can be controlled.

  A removal device for removing the substance eluted in the acid solution can be installed to measure the concentration of the acid solution and regenerate it in parallel. Therefore, reproduction is possible without using large-scale equipment. Preferably, by using a graft polymerized filter, specific metal ions in the acid solution sample for concentration measurement can be removed, and the etching solution can be regenerated. Preferably, a bypass line is provided in parallel with the removing device. Thereby, the concentration of the eluted substance in the etching solution can be controlled to an appropriate value.

  Further, in the concentration measurement using the spectroscopic measurement, the concentration of the acid in the acid solution and the substance eluted in the acid solution can be determined simultaneously in a short time. By using a flow cell, in-line concentration measurement is possible. Further, concentration control can be continuously performed during an etching process or the like. Further, since the metal contained in the sample acid solution from the cell can be removed by the removing device, the concentration control and regeneration of the acid solution can be continuously performed during the etching process and the like.

  Embodiments of the present invention will be specifically described below with reference to the accompanying drawings.

  In applications such as etching of various materials such as copper, aluminum, silicon, and steel, various acid solutions (chemicals) such as hydrochloric acid overwater, aqua regia, phosphoric acid nitrate acetic acid, and ferric chloride are used. For example, hydrochloric acid overwater is used in etching copper such as printed circuit boards. Hydrochloric acid overwater refers to a solution composed of hydrochloric acid, hydrogen peroxide and water. Etching is performed by immersing an object to be etched in an etching tank, spraying an etching solution, or the like. The management of the acid solution in the etching process or the like is performed based on the measurement of the concentration of the acid in the acid solution and the concentration of the substance dissolved by the acid solution.

  FIGS. 1 and 2 show a system 20 that performs acid concentration measurement, concentration control, and regeneration in an etching bath 10. The etching tank 10 is filled with, for example, hydrochloric acid / hydrogen peroxide as an etching solution, and copper such as the printed circuit board is etched by immersing the printed circuit board or the like therein. In this system, in order to manage the etching process, an etchant sample is introduced from the etching tank 10, the spectrum of the transmitted light or reflected light is measured, and the absorbance is obtained. Then, the concentration of the acid and the concentration of the substance eluted by the acid are obtained using the absorbance and the calibration curve formula. Then, the etching solution is managed and regenerated based on the measured concentration value. The sampling unit 30 includes a liquid feed pump 32 and operates the liquid feed pump 32 to continuously take samples of the etchant from the etching tank 10. The concentration measurement unit 40 is a spectroscopic measurement device, which applies light in the ultraviolet region, visible region, and near-infrared region to a sample to be measured that enters the cell, and calculates the intensity of light transmitted or reflected from the sample. Convert to density value.

  The concentration measuring unit 40 can be installed in-line in the hydrochloric acid / hydrogen peroxide supply line. Specifically, the concentration measuring unit 40 is a spectroscopic measurement device, for example. For this reason, the concentration of hydrochloric acid, hydrogen peroxide, and copper in the acid solution can be continuously quantified during the etching process quickly, simply and accurately without altering the acid solution as a sample. Based on this, the product yield can be improved.

  The sample from the etching tank 10 is spectroscopically measured by the concentration measuring unit 40 and then returned to the etching tank 10 after the eluted metal is removed by the removing device 50. In this closed circulation loop, concentration measurement and etching solution regeneration can be performed in a short time (about 10 minutes). Even if only the acid concentration is constant, the etching rate varies depending on the amount of the eluted material. By removing the eluted metal using the removing device 50, it is possible to perform process control that stabilizes the etching rate (degree of etching) while keeping the acid concentration constant.

  A metal removal filter is used as the removal device 50. The metal removal filter is a graft-polymerized filter, and can capture specific metal ions contained in the chemical liquid that has passed through the liquid feed pump 32. It is known that filters using radiation graft polymerization can be used for waste liquid treatment or the like (for example, JP-A-8-199480, JP-A-2002-20959, etc.).

  Further, it may be preferable to leave some of the metal eluted in the etching solution without completely removing it in the process control. Therefore, as shown in FIG. 2, a bypass line is provided in parallel to the metal removal filter as the removal device 50, and valves 52 and 54 are provided at the inlets to both. Then, by controlling the valves 52 and 54 based on the concentration measurement value obtained by the concentration measuring unit 40, the amount of the eluted metal in the etching solution is controlled to an appropriate value.

  The concentration measuring unit 40 is a spectroscopic measurement device in this embodiment. FIG. 3 shows the configuration of the concentration measuring unit 40 that measures the light intensity of the etching solution sample. The concentration measuring unit 40 is substantially composed of a spectroscopic unit, a sampling unit, and a data processing unit. In the concentration measurement, a verification line formula is obtained in advance. First, a sample of an acid solution having a known concentration is introduced into a light transmission or reflection detection cell, light is transmitted or reflected, and the light intensity of the transmitted light or reflected light is measured. This measurement is repeated for a plurality of samples. Next, the absorbance is calculated from the intensity values of the plurality of samples, and a calibration curve equation between the absorbance, the acid concentration in the acid solution, and the concentration of the eluted substance is obtained. Next, an acid solution to be measured is introduced into the cell, light is transmitted or reflected, and the light intensity of transmitted light or reflected light is measured. Then, the absorbance is calculated from the light intensity value, and both the acid and the concentration of the eluted substance in the acid solution are determined using the absorbance and the calibration curve equation.

  First, the spectroscopic unit will be described. For example, the light source 100 that generates light in the wavelength range of 350 to 2000 nm is used. The light emitted from the light source 100 is collected by the first convex lens 102 and passes through the diaphragm 104 and the interference filter 106 arranged at the focal position of the first convex lens 102. The rotating disk 108 holds a plurality of (for example, eight) interference filters 106 at equal angular intervals in the circumferential direction, and is rotationally driven by the drive motor 110 at a predetermined number of rotations (for example, 1000 rpm). Here, the interference filter 106 separates the light that has passed through the aperture 104 into light having a plurality of predetermined wavelengths. The light dispersed by the interference filter 106 is collected by the second convex lens 112 and irradiates the flow cell 114. A sampled etchant is continuously introduced into the flow cell 114. By using the flow cell 114, the concentration can be continuously measured in-line. A part of the light irradiated to the flow cell 114 is absorbed by the etching solution, and the remaining part is transmitted through the flow cell 114. The light transmitted through the flow cell 114 is collected by the third convex lens 116 and is incident on the light receiving element 118. When the rotating disk 108 is rotationally driven by the drive motor 110, the light receiving element 118 corresponds to the acid solution in the flow cell of light corresponding to the transmission wavelengths of the plurality of interference filters 106 held on the rotating disk. Generate a signal that is proportional to the transmission (or reflection). The light receiving element 118 converts the incident light into a photocurrent corresponding to the intensity thereof.

  Each interference filter 106 held by the rotating disk 108 has different transmission wavelengths depending on the measurement target. When the rotating disk 108 rotates, the interference filters 106 are sequentially inserted into the optical axes of the first convex lens 102 and the second convex lens 112. The light emitted from the light source 100 is dispersed by the interference filter 106, passes through the sample in the flow cell 114 (partly absorbed), is collected by the third convex lens 116, and enters the light receiving element 118. The Thereby, the light receiving element 118 outputs an electric signal corresponding to the light intensity of each wavelength. The amplifier 120 amplifies the transmitted light (or reflected light) intensity signal output from the light receiving element 118 and the A / D converter 122 converts the analog signal output from the amplifier 120 into a digital signal. .

  Next, a specific configuration of the data processing unit 130 will be described. The data processing unit 130 receives a transmitted light (or reflected light) intensity signal, which is a digital signal, from the A / D converter 122, and then calculates the absorbance at each wavelength. Then, based on the calculated absorbance at each wavelength and the calibration curve formula stored in advance, the concentrations of the three components of hydrochloric acid, hydrogen peroxide and copper are calculated. A calibration curve is a multivariate measurement using a multi-degree polynomial of absorbance that measures the absorbance of light of multiple wavelengths for multiple samples of known concentrations and contains a constant term between the absorbance and the concentration of each component. It is obtained in advance by an analysis method and held in the storage device (RAM 136). As described above, when the rotary disk 108 is rotationally driven by the drive motor 110, the light receiving element 118 transmits the transmittance corresponding to the acid solution in the flow cell 114 (or the light corresponding to the transmission wavelength of the interference filter 106 (or A signal proportional to (reflectance) is generated. These signals are amplified by the amplifier 120, converted into digital signals by the A / D converter 122, and input to the microprocessor 132 of the data processing device 130. The data processing unit 130 is a personal computer including a microprocessor 132, for example. Connected to the microprocessor 132 are a ROM 134 for storing programs, a RAM 136 as a work area, a keyboard for inputting data and various commands, an input device 138 such as a mouse, and an output device 140 for outputting signals to the outside. . The ROM 134 stores a program for operating the microprocessor 132 and the like. The RAM 136 stores a calibration curve type and various data. The microprocessor 132 calculates the absorbance at each wavelength from the input digital signal, and calculates the concentration of the acid and the eluted substance in the drug solution from the calculated absorbance of the light of each wavelength using a calibration curve formula. The output device 140 is a printer, a display, a data output interface, or the like that outputs data processing results.

  4 and 5 show a processing flow of the microprocessor 132. FIG. First, when measurement of a sample having a known concentration is started (S10), light intensity data at a plurality of wavelengths is input from the A / D converter 122 of the light measurement system in synchronization with the rotation of the rotating disk 108 (S12). ). Then, the absorbance is calculated from the light intensity data and stored (S14). If there is a sample of the next known concentration (YES in S16), the above process is repeated. If there is no sample of the next known concentration (NO in S16), a calibration curve formula between absorbance and concentration is calculated (S18) and stored in the RAM 136 (S20).

  When measurement of an unknown concentration sample is started (S22), light intensity data at a plurality of wavelengths is input from the A / D converter 122 of the light measurement system in synchronization with the rotation of the rotating disk 108 (S24). Then, the absorbance is calculated from the light intensity data (S26). Then, the concentration is calculated from the absorbance and the calibration curve formula (S28) and stored in the RAM 136 (S30). If the measurement is not completed (NO in S32), the process returns to step 24 to continue the concentration measurement.

  The processing method of the light intensity data in the processing of the microprocessor 132 shown in FIG. 5 is that described in Japanese Patent Laid-Open No. 6-265471 by the present applicant, which was used for spectroscopic measurement in the near infrared wavelength region. It is the same. The specific contents of this data processing method will be described below.

この式において、ｉは、分光された複数の波長の光の順番ないし番号（たとえば、１〜８）であり、Ｒ_ｉは、測定対象である酸溶液のｉ番目の波長の光の透過（または反射）光強度値であり、Ｂ_ｉは、フローセル１１４内に導入された基準濃度の酸溶液の、ｉ番目の波長の光の透過（または反射）光強度値であり、Ｄ_ｉは、フローセル１１４を遮光したときのｉ番目の波長の光の透過（または反射）光強度値である。なお、Ｂ_ｉおよびＤ_ｉは、あらかじめ測定されているデータであり、データ処理装置のＲＡＭ１３６に格納されている。 First, a calculation process according to the following equation (1) is performed on the input digital signal of light intensity to calculate the absorbance A _i .

In this formula, i is the order or number (for example, 1 to 8) of the light having a plurality of wavelengths separated, and R _i is the transmission (or the light of the i-th wavelength of the acid solution to be measured) (or B _i is the transmitted (or reflected) light intensity value of the i-th wavelength light of the acid solution of the reference concentration introduced into the flow cell 114, and D _i is the flow cell 114. Is the transmitted (or reflected) light intensity value of light of the i-th wavelength when the light is shielded. B _i and D _i are data measured in advance, and are stored in the RAM 136 of the data processing apparatus.

Next, the following equation (2) is converted into the absorbance A _i obtained by the arithmetic processing according to equation (1).

The reason for performing the conversion of equation (2) is as follows. The absorbance A _i calculated by the equation (1) changes due to fluctuations in the light emission intensity of the light source 4, sensitivity fluctuations in the light receiving element 118, distortion of the optical system, and the like. However, this change is not very wavelength-dependent, and is superimposed in the same phase and at the same level on each absorbance data for each wavelength of ultraviolet light. Therefore, this change can be offset by taking the difference between the wavelengths as shown in Equation (2).

Incidentally, with variation or deterioration of the absorbance A _i due to temperature variations of the acid solution itself, but also occurs such fluctuations due to an increase in color change and turbidity, these variations are well known methods (e.g. Japanese Patent Laid-Open 3-209149 The description thereof will be omitted.

Next, the density is calculated based on _Si obtained by the equation (2). Here, the case of hydrochloric acid overwater as a copper etching solution will be described. For the three components (hydrochloric acid, hydrogen peroxide and copper) in the etching solution, the following equations (3) to (5) are calculated, the content of the (concentration) C _1, and calculates the content of hydrogen peroxide (the concentration) C _2, and a content (concentration) C ₃ of eluted copper.

式（６）において、Ｓ_ｉとＳ_ｉ＋１は式（１）と式（２）により得られたデータであり、α、βおよびγは検量線式の係数であり、Ｚ_０は定数項である。式（６）に含まれる各データは、塩酸、過酸化水素及び銅の濃度が既知の酸溶液の標準サンプルを用いて濃度測定部４０による測定によりあらかじめ求められたものであり、データ処理装置１３０のＲＡＭ１３６に格納されている。 In the formula _{(3), F (S i} ) is a calibration curve equation hydrochloride, with including first-order terms and higher order terms for S _i, cross terms and a S _i and S _{i + 1} or the product of the higher order terms Including a constant term, for example, expressed by the following equation (6).

In Equation (6), S _i and S _{i + 1} are data obtained by Equation (1) and Equation (2), α, β, and γ are coefficients of the calibration curve equation, and Z ₀ is a constant term. . Each data included in the equation (6) is obtained in advance by measurement by the concentration measuring unit 40 using a standard sample of an acid solution having known concentrations of hydrochloric acid, hydrogen peroxide, and copper. Stored in the RAM 136.

In the formulas (4) and (5), G (S _i ) and H (S _i ) are a hydrogen peroxide calibration curve and a copper calibration curve, respectively. Is an expression of the same form as Similar to the calibration curve formula for hydrochloric acid, these calibration curve formulas are obtained in advance by the concentration measuring unit 40 using standard samples of acid solutions with known concentrations of hydrochloric acid, hydrogen peroxide and copper, and data It is stored in the RAM 136 of the processing unit 130.

The microprocessor 132 of the data processing device 130 of the concentration measuring unit 40 outputs the hydrochloric acid content C ₁ , the hydrogen peroxide content C _2, and the copper content C ₃ to an output device 140 such as a CRT or a printer. , Displayed on a CRT screen, or output as a hard copy on printing paper, and transmitted to an external medicine addition module 60.

  The case where the concentration of the three components is obtained has been described above, but the same processing can be performed for cases other than the three components such as the two components.

  FIG. 6 shows an example of a spectrum in the visible wavelength region and near infrared wavelength region of an acid solution for copper etching. As shown in FIG. 6, the spectral spectrum due to the acid and copper in the etching solution changes in the visible wavelength region and the near-infrared wavelength region before and after etching. The acid concentration and the copper content are determined by spectroscopic measurement in the visible wavelength region and the near infrared wavelength region. Therefore, in order to obtain the concentration of acid and copper in the etching solution, the spectroscopic measurement is performed at wavelengths in the visible region and near infrared region (for example, 350 to 2000 nm). Therefore, in the spectroscopic device shown in FIG. 3, the interference filter 106 provided on the rotating disk 108 transmits light having a plurality of discrete wavelengths within a wavelength range of 350 to 2000 nm. Thereby, the density | concentration of the acid in an etching liquid and copper can be determined simultaneously from spectral data. In the case of detecting an eluting substance other than copper, it can be measured in the same manner if it changes in the visible wavelength region and the near-infrared wavelength region. Thus, the concentration of the acid in the acid solution and the substance eluted in the acid solution can be simultaneously determined in a short time by spectroscopic measurement. Since a flow cell is used, in-line measurement is possible.

  Explaining the wavelength range of the spectroscopic measurement, the measurement of the concentration of the aqueous solution uses an appropriate wavelength range among the ultraviolet wavelength range of 190 to 400 nm, the visible wavelength range of 400 to 800 nm, and the near infrared wavelength range of 800 to 2000 nm. Is done. The characteristics of the acid solution appear greatly in the near-infrared wavelength region, and the characteristics of the eluted substance appear greatly in the visible wavelength region and the ultraviolet wavelength region. (In the example of FIG. 6, the characteristics of the eluted copper appear largely in the vicinity of 800 nm.) Although the wavelength range is 350 to 2000 nm in the above example, it may be widely 190 to 2000 nm. In general, the spectroscopic measurement may be performed in an appropriate wavelength region in which the characteristics of the acid solution and the characteristics of the eluted substance can be detected. Absorbance is measured discretely from several points to several tens of points within the wavelength range. Note that the absorbance at a characteristic wavelength varies depending on the object to be measured (for example, hydrochloric acid and water), so even when the same concentration is measured, the standard deviation and correlation coefficient differ. In other words, there are ones that are easy to measure and ones that are difficult to measure depending on what the composition is. Therefore, an appropriate wavelength may be selected.

As described above, the acid and substance concentrations in the acid solution are calculated based on the absorbance (reflectance) of each wavelength in the ultraviolet region, visible region, and near infrared region, and the calibration curve equation. In the following example, the etchant is hydrochloric acid overwater and is used for etching copper. Table 1 shows a measurement of 42 standard samples of known concentrations (containing copper in hydrochloric acid perwater) by means of the spectroscopic device 40 for hydrochloric acid, hydrogen peroxide (abbreviated as “super water”) and copper. It shows the concentration (theoretical value (wt%, ppm)) obtained by calculation from the absorbance and the actual concentration (measured value (wt%, ppm)) of the standard sample.

  8, FIG. 9, and FIG. 10 show the correlation between the known concentration (theoretical value) and the actual concentration (measured value) for the standard samples shown in Table 1 for hydrochloric acid, hydrogen peroxide, and copper, respectively. Show the relationship. High correlation was obtained for both.

  In the above example, the interference filter 106 in which the wavelength to be extracted is changed stepwise is used as a discrete spectrum, but a continuous spectrum may be used. When measuring a continuous spectrum, an optical system capable of continuously changing the wavelength to be extracted may be used. When a continuous spectrum is used, the measurement and calculation time of light intensity is longer than when calculation is performed using discrete data (for example, 8 points), but high-accuracy measurement is possible because the amount of information increases.

  Next, the concentration control will be described. The drug addition module 60 controls a tank (not shown) of a drug (new liquid and composition chemical liquid and pure water contained therein) for regeneration of the acid solution, and chemical liquid addition. And a supply valve 64 for supplying a chemical from each tank to the etching tank 10 and a waste liquid valve 66 for discharging the waste liquid from the etching tank 10. In the example shown in the figure, four tanks of hydrochloric acid, hydrogen peroxide solution, hydrochloric acid peroxide solution and pure water are provided for the etching solution of peroxide solution.

  FIG. 7 is a flowchart of concentration control in the chemical liquid addition control unit 62. When the chemical solution addition control unit 62 receives the concentration data of hydrochloric acid and hydrogen peroxide from the concentration measurement unit (spectrometer) 40 (S50), based on the concentration, the chemical solution addition control unit 62 stores the drug tank in the drug addition module 60 at the present time. Ascertain the state, and from these data, parameter values necessary for the management of the chemical tank, for example, the amount of stock solution added from the tank (the amount of input chemical solution), the time of stock solution addition, and the amount of waste liquid discharged from the etching tank 10, The waste liquid time is calculated (S52). Here, if necessary, the opening / closing time of the valves 52 and 54 of the removing device 50 is further calculated. Then, when it is determined from the calculation result that a drug needs to be added, the result is output to the output device 140 (S54). Based on the result, the output device 140 controls each valve 64 of the input chemical liquid tank, the waste liquid valve 66 and the valves 52 and 54 of the removing device 50 to open and close for a predetermined time. As a result, the necessary stock solution and the like are supplied to the etching tank 10 and the waste liquid is discharged from the etching tank 10, so that the concentration of the etching liquid in the etching tank 10 can be kept constant. Until the etching process is completed (NO in S56), the process returns to Step S50 and the concentration control is continued. As described above, the concentration control of the acid solution in the tank can be continuously performed during the etching process by opening and closing the valves 64, 66, 52, and 54 based on the concentration measurement data.

  The sample after the concentration measurement is sent to the metal removal filter 50 as described above, and is returned to the etching tank 10 after removing the metal in the sample. Therefore, the acid solution can be regenerated in parallel with the etching without using a large facility. Further, since the copper contained in the sample acid solution from the flow cell is removed by the metal removal filter 50, the concentration regeneration can be continuously performed during the etching process.

  In the above-described example, the etching of copper using hydrochloric acid overwater has been described. However, it goes without saying that the concentration control and regeneration of the acid solution described above is not limited to acid solutions other than hydrochloric acid / hydrogen peroxide (for example, etching solutions such as aqua regia, phosphoric acid nitrate acetic acid, ferric chloride, etc.) and elution substances other than copper. It can also be applied.

  In the above example, the concentration is measured using the spectroscopic measurement device. Instead of using the spectroscopic measurement device, the optical measurement probe (not shown) is immersed in the etching tank 10 to measure the concentration, and the concentration data. May be sent to the concentration control device (chemical solution addition module 60). In this case, the etching solution in the etching tank 10 is sent directly to the metal removal filter 50 (and the bypass line). Then, after the contained metal is removed, it is returned to the etching tank 10.

Block diagram of a system that measures and regenerates the concentration of an acid solution in an etching bath Diagram of part of a system that measures and regenerates the concentration of acid solution in the etching bath The figure which shows an example of a structure of a density | concentration measurement part Microprocessor data processing flowchart Microprocessor data processing flowchart Graph showing one example of spectral change in visible and near infrared wavelength range due to copper etching Flow chart for controlling the chemical addition module For hydrochloric acid, a graph showing the correlation with the actual concentration (measured value) of a standard sample of the known concentration (theoretical value) shown in Table 1 A graph showing the correlation between the hydrogen peroxide solution and the actual concentration (measured value) of a standard sample of the known concentration (theoretical value) shown in Table 1. About copper, the graph which shows the correlation with an actual density | concentration (measurement value) about the standard sample of the known density | concentration (theoretical value) shown in Table 1

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Etching tank, 20 System which performs density | concentration measurement and reproduction | regeneration of acid solution, 30 Sampling part, 32 Liquid feed pump, 40 Concentration measuring part (spectrometer), 50 Metal removal filter, 52,54 Valve of removal apparatus 50, 60 Chemical solution addition module, 62 concentration controller, 64 supply valve, 66 waste liquid valve.

Claims (11)

A tank containing an acid solution;
A concentration measuring device that determines both the concentration of the acid and the concentration of the substance eluted in the acid solution for the acid solution in the tank;
A tank containing a stock solution of the acid solution;
A supply device for supplying the stock solution from the tank to the tank;
A discharge device for discharging the acid solution from the water tank;
Based on the concentration obtained by the concentration measuring device, an acid solution stock solution is supplied from the tank by the supplying device, the acid solution in the tank is discharged by the discharging device, and the acid in the acid solution in the tank is discharged. An acid solution regeneration system comprising a concentration control device for controlling the concentration.   2. The acid solution regeneration system according to claim 1, wherein the stock solution of the tank is a new acid solution, a composition chemical solution and pure water contained therein.   The concentration control device receives concentration data from the concentration measuring device, calculates a supply amount of the supply device and a discharge amount of the discharge device, and based on the calculated supply amount and discharge amount, the supply device and the discharge amount The acid solution regeneration system according to claim 1 or 2, wherein the apparatus is controlled.   The apparatus further comprises a removing device for introducing the acid solution from the tank, removing the eluted substance in the introduced acid solution, and returning the acid solution from which the eluted substance has been removed to the tank. The acid solution regeneration system described in any of the above.   5. The acid solution regeneration system according to claim 4, wherein the removing device includes a filter subjected to a plasma graft polymerization process to adsorb specific metal ions.   The acid solution regeneration system according to claim 4 or 5, further comprising a bypass line in parallel with the removing device. The concentration measuring device is a spectroscopic measuring device.
A light transmission or reflection detection cell into which the acid solution sample to be measured is introduced;
A light source that irradiates the cell with light having a wavelength within the wavelength range of ultraviolet light, visible light, and near-infrared light;
A spectroscopic means for spectroscopically analyzing transmitted light or reflected light obtained by irradiating the cell with light from a light source;
A light receiving means for receiving light split by the spectroscopic means and generating a light intensity signal corresponding to the intensity of the received light;
Storage means for storing a calibration curve formula indicating the relationship between the concentration of acid in the acid solution and the concentration of the substance eluted in the acid solution and the absorbance;
Concentration calculating means for calculating the absorbance from the light intensity signal input from the light receiving means and simultaneously determining the concentration of the acid in the acid solution and the concentration of the substance eluted in the acid solution from the absorbance based on the calibration curve equation The acid solution regeneration system according to any one of claims 1 to 6, characterized by comprising:   7. The acid solution regeneration system according to claim 6, wherein a cell of the spectroscopic measurement device is disposed in a path of the acid solution between the tank and the removal device.   The acid solution regeneration system according to any one of claims 1 to 6, wherein the concentration measuring device is a spectroscopic measurement probe that is immersed in the tank and performs concentration measurement. A light transmission or reflection detection cell into which the acid solution sample to be measured is introduced;
A light source that irradiates the cell with light having a wavelength within the wavelength range of ultraviolet light, visible light, and near-infrared light;
A spectroscopic means for spectroscopically analyzing transmitted light or reflected light obtained by irradiating the cell with light from a light source;
A light receiving means for receiving light split by the spectroscopic means and generating a light intensity signal corresponding to the intensity of the received light;
Storage means for storing a calibration curve formula indicating the relationship between the concentration of acid in the acid solution and the concentration of the substance eluted in the acid solution and the absorbance;
Concentration calculating means for calculating the absorbance from the light intensity signal input from the light receiving means and determining both the concentration of the acid in the acid solution and the concentration of the substance eluted in the acid solution from the absorbance based on the calibration curve equation Concentration measuring device consisting of In measuring the concentration of acids in acid solutions and substances eluted in acid solutions,
For the acid solution sample to be measured, measure the intensity of transmitted or reflected light of wavelengths within the wavelength range of ultraviolet light, visible light and near infrared light,
Calculate the absorbance from the light intensity signal,
A concentration measurement method that calculates both the concentration of the acid in the acid solution and the concentration of the substance eluted in the acid solution from the absorbance based on a calibration curve equation that is determined in advance.

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