JP5024521B2 - Method and apparatus for producing high-temperature and high-concentration persulfuric acid solution - Google Patents

Description

  The present invention relates to a method and an apparatus for producing a high-temperature high-concentration persulfuric acid solution that is suitably used for producing and regenerating a washing liquid for washing electronic components.

  In a technique for cleaning an electronic material substrate such as a silicon wafer, a liquid crystal glass substrate, and a photomask substrate, a mixed solution (SPM) of concentrated sulfuric acid and hydrogen peroxide solution is usually used in a process of peeling and cleaning the resist. It is known that the cleaning effect by SPM is due to the high oxidation resolution of persulfuric acid (peroxodisulfuric acid) produced by oxidizing hydrogen peroxide with sulfuric acid.

In addition to the above method, a method for producing persulfate ions by electrolyzing an aqueous solution containing sulfate ions in an electrolytic bath to obtain persulfate ion-dissolved water (sulfuric acid electrolysis method) is also known. (See Patent Documents 1 and 2).
JP 2001-192874 A Special table 2003-511555 gazette

  However, in SPM, hydrogen peroxide solution needs to be replenished to compensate for the decomposition of persulfuric acid generated by hydrogen peroxide when it decomposes itself and its oxidizing power decreases. However, since the sulfuric acid concentration is gradually diluted by the addition of hydrogen peroxide solution, it is difficult to maintain the liquid composition constant, and the cleaning liquid is discarded and updated every predetermined time or every predetermined processing amount. For this reason, there is a problem that a large amount of chemicals must be stored and discarded. In this method, the concentration of persulfuric acid produced is limited, which leads to the limit of the cleaning effect.

  On the other hand, the sulfuric acid electrolysis method can continuously generate persulfuric acid, but electrolysis of sulfuric acid at high temperature or high concentration results in poor electrolysis efficiency and cannot generate persulfuric acid to a high persulfuric acid concentration. Therefore, it was necessary to perform electrolysis using low-temperature and low-concentration sulfuric acid. Also, especially in the case where high cleaning ability such as ashless is required in the manufacture of electronic material substrates, the cleaning liquid needs to be at a high temperature. However, at high temperatures, the persulfuric acid concentration is high due to the high self-decomposition rate of persulfuric acid. It also has a problem that it is difficult to maintain.

  The present invention has been made against the background of the above circumstances, and a continuous high-temperature sulfuric acid solution containing a high concentration of persulfate ions capable of effectively stripping and removing and decomposing resist deposits such as semiconductor wafers. It is an object of the present invention to provide a method and an apparatus for producing a high-temperature and high-concentration persulfuric acid solution that can be produced and supplied to a container.

That is, in the method for producing a high-temperature high-concentration persulfuric acid solution according to the present invention, the invention described in claim 1 is the sulfuric acid contained in the solution by repeatedly performing an electrolytic reaction while circulating a solution containing sulfate ions at a concentration of 10 to 18M. When producing a high-concentration persulfate solution having a persulfate ion concentration higher than that of the solution before electrolysis by generating persulfate ions from ions, and supplying the high-concentration persulfate solution to the persulfate-use side The high-concentration persulfuric acid solution contains sulfate ions at a concentration of 10 to 18M , and the concentration difference is equal to or less than 2M in the concentration of the sulfate ions in the solution subjected to the electrolytic reaction. characterized by a high-temperature and high-concentration persulfuric acid solution having a higher temperature than the high-concentration persulfuric acid solution before mixing by mixing hot solution than.

The method for producing a high-temperature high-concentration persulfuric acid solution according to claim 2 is the invention according to claim 1, wherein the high-temperature solution containing sulfate ions is newly supplied from outside the system, and includes a solution containing sulfate ions Alternatively, it is characterized in that the recovered solution recovered after being used on the persulfuric acid use side and decreasing the persulfate ion concentration is heated .

The invention of the method for producing a high-temperature high-concentration persulfate solution according to claim 3 is characterized in that persulfate ions are converted from sulfate ions contained in the solution by repeatedly performing an electrolytic reaction while circulating a solution containing sulfate ions at a concentration of 10 to 18M. When producing a high concentration persulfuric acid solution having a higher concentration of persulfate ions than the solution before electrolysis and supplying the high concentration persulfuric acid solution to the persulfuric acid use side, The solution contains sulfate ions at a concentration of 10 to 18 M, and is a higher temperature solution than the high-temperature persulfate solution, and is used after the persulfate ion concentration is reduced after being used on the persulfuric acid use side. A high-temperature high-concentration persulfuric acid solution having a temperature higher than that of the high-concentration persulfuric acid solution before mixing is mixed .

  The invention of the method for producing a high-temperature high-concentration persulfuric acid solution according to claim 4 is the high-temperature high-temperature perfusion solution according to any one of claims 1 to 3, wherein a high-temperature solution containing sulfate ions is mixed with the high-concentration persulfuric acid solution. The high-concentration persulfuric acid solution is further heated.

  The method for producing a high-temperature high-concentration persulfuric acid solution according to claim 5 is the invention according to any one of claims 1 to 4, wherein the temperature of the solution containing sulfate ions circulated in the electrolytic reaction is 10 to 70. It is characterized by being at ° C.

  The invention of the method for producing a high-temperature high-concentration persulfuric acid solution according to claim 6 is the invention according to any one of claims 1 to 5, wherein the temperature of the high-temperature solution containing sulfate ions is 130 to 200 ° C. It is characterized by that.

  The invention of the method for producing a high-temperature high-concentration persulfate solution according to claim 7 is the invention according to any one of claims 1 to 6, wherein the mixing ratio of the high-concentration persulfate solution to a high-temperature solution containing sulfate ions Is 1:10 to 1: 1.

  The invention of the method for producing a high-temperature high-concentration persulfuric acid solution according to claim 8 is the invention according to any one of claims 1 to 7, wherein the temperature of the high-temperature high-concentration persulfuric acid solution supplied to the persulfuric acid use side is 100 to 190 ° C.

The invention of the high temperature high concentration persulfuric acid solution generator according to claim 9 includes an electrolytic reaction device for generating persulfate ions from sulfate ions contained in the solution at a concentration of 10 to 18 M by electrolytic reaction, and the sulfate ions. A storage tank for storing the solution, a circulation line for transferring the solution from the storage tank as an electrolytic solution to the electrolytic reaction apparatus, and for transferring the solution electrolyzed from the electrolytic reaction apparatus to the storage tank, and the electrolytic reaction look containing persulfate ions generated in the apparatus, the electrolytic and high concentration persulfate supply line for supplying the persulfate solution persulfate consuming with increased persulfate ion concentration than the previous solution which undergoes,該過sulfate comprising sulfate ions at a concentration of 10~18M to the supply line, characterized in that it comprises a high-temperature sulfuric acid solution supply line, wherein the high concentration by supplying hot solution than persulfate solution is mixed into the high-concentration persulfuric acid solution To.

  The invention of the apparatus for producing a high-temperature high-concentration persulfuric acid solution according to claim 10 is the invention according to claim 9, wherein the electrolytic solution transferred to the electrolytic reaction device or the electrolytic solution transferred from the electrolytic reaction device is An electrolyte solution cooling means for cooling is provided.

  The invention of the apparatus for producing a high-temperature high-concentration persulfuric acid solution according to claim 11 is the sulfuric acid newly supplied from outside the system as the electrolyte to be transferred to the electrolytic reaction device in the invention according to claim 9 or 10. A replenishment line is provided for replenishing a solution containing ions or a recovered solution used after the persulfate ion concentration is reduced by using the persulfate.

  The invention of the apparatus for producing a high-temperature high-concentration persulfuric acid solution according to claim 12 is the invention according to any one of claims 9 to 11, wherein the high-temperature sulfuric acid solution supply line is newly supplied from outside the system. A high-temperature sulfuric acid solution supply line heating means configured to supply a solution containing ions or a recovered solution that is used after the persulfate ion concentration is reduced and is recovered after the persulfate ion concentration is reduced. It is characterized by providing.

  The invention of the device for producing a high-temperature high-concentration persulfuric acid solution according to claim 13 is the invention according to any one of claims 9 to 12, wherein the persulfuric acid supply line is mixed with the high-temperature solution containing the sulfate ions. A first persulfate supply line heating means for heating the solution containing the persulfate ions, and a second persulfate supply line heating means for heating the solution containing the persulfate ions after the mixing. And

  A high-temperature high-concentration persulfuric acid solution generator according to claim 14 is the invention according to any one of claims 9 to 13, wherein the persulfuric acid use side is a cleaning system using persulfuric acid. And

That is, according to the present invention, persulfate ions are generated by causing the electrolytic reaction device to perform an electrolytic reaction with a pair of the anode and the cathode using a solution containing sulfate ions. The material of these electrodes is not limited to a specific one in the present invention. However, when platinum, which is widely used as an electrode, is used as the anode of the electrolytic reaction apparatus of the present invention, there is a problem that persulfate ions cannot be produced efficiently and platinum is eluted. On the other hand, the diamond electrode can efficiently generate persulfate ions and has little electrode wear. Therefore, it is desirable that at least one of the electrodes of the electrolytic reaction apparatus, in particular, at least the anode capable of generating persulfate ions be composed of diamond electrodes, and it is more desirable that both the anode and cathode be composed of diamond electrodes. .
The conductive diamond electrode is a semiconductor material such as a silicon wafer used as a substrate, and after synthesizing a conductive diamond thin film on the wafer surface, the wafer is dissolved or synthesized in a plate shape under the condition that the substrate is not used. There may be mentioned free-standing conductive polycrystalline diamond.

  The conductive diamond thin film is a conductive thin film that is doped with a predetermined amount of boron, nitrogen, or the like during synthesis of the diamond thin film, and is generally boron-doped. If the doping amount is too small, the technical significance does not occur. If the doping amount is too large, the doping effect is saturated. Therefore, a doping amount in the range of 50 to 20,000 ppm with respect to the carbon amount of the diamond thin film is suitable. . As the conductive diamond electrode, a plate-like one is usually used, but a plate having a network structure can also be used. That is, in the present invention, the shape and number of electrodes are not particularly limited.

In the electrolytic treatment performed using the conductive diamond electrode, the current density on the surface of the conductive diamond electrode is set to 10 to 100,000 A / m ^2, and a solution containing sulfate ions is parallel to the diamond electrode surface and the liquid passage speed is set. It is desirable to perform contact treatment at 1 to 10,000 m / hr.

In the above electrolysis reactor, the electrolysis is performed while circulating the solution between the storage tank through the circulation line, so that the persulfate ion concentration can be sufficiently increased, and when high-concentration sulfuric acid is used as the electrolyte solution. Also, a high persulfate ion concentration can be obtained. This solution containing persulfate ions can be supplied to the appropriate persulfate use side through a persulfate supply line.
When the sulfuric acid concentration of the electrolyzed solution is about 2 to 9M, the persulfate ion generation efficiency by electrolysis increases. However, when the electrolyzed solution is used as a cleaning solution, the sulfuric acid concentration is the concentration of organic substances such as resist from the electronic material substrate. It greatly affects the removal effect. The peeling / dissolving effect of organic substances such as resist decreases with decreasing sulfuric acid concentration. Therefore, the inventors have repeated various experiments and found that the sulfuric acid concentration in the range of 10M to 18M is an appropriate concentration in consideration of electrolysis efficiency and cleaning efficiency.

In addition, the suitable temperature of the solution in an electrolytic reaction apparatus is 10-60 degreeC. When the temperature range is exceeded, the electrolysis efficiency decreases and the wear of the electrode also increases. Moreover, as a result of electrolysis, the solution temperature rises and the self-decomposition of persulfate ions is accelerated. On the other hand, if the temperature is lower than the above temperature, when the electrolytic solution is used as a cleaning solution, the heat energy for heating to increase the cleaning effect becomes enormous, which is not practical. For the same reason, it is more desirable to set the lower limit to 25 ° C. and the upper limit to 45 ° C.
In addition, since the solution circulating through the storage tank and the electrolytic reaction device becomes relatively high as a result of electrolysis, the electrolytic solution cooling means such as a heat exchanger when transferring to the storage tank or the electrolytic reaction device It is desirable to provide cooling. As a result, the solution circulating in the storage tank and the electrolytic reaction device is maintained within a range of 10 to 70 ° C. to enable a good electrolytic reaction and suppress the self-decomposition of persulfate ions generated by the electrolytic reaction. be able to.

  Moreover, in the said system, the to-be-electrolyzed solution supplied to an electrolytic reaction apparatus can be replenished by providing a replenishment line. As the solution to be replenished, a solution containing sulfate ions newly supplied from the outside of the system or a recovered solution recovered after the persulfate ion concentration is decreased on the persulfuric acid use side can be used. The replenishing solution can be directly supplied to a circulation line, a storage tank, or an electrolytic reaction device. When the replenishing solution is hot, it is desirable that the solution be cooled via the cooling means.

A high-concentration persulfate solution in which persulfate ions are sufficiently high by repeated electrolysis is supplied to the persulfate use side in various applications. The persulfuric acid use side is not particularly limited as the present invention, and can be applied to various uses that require persulfate ions. As described above, a suitable use example is one that is used for cleaning a semiconductor wafer or the like by generating persulfate ions in a sulfuric acid solution.
However, a high-concentration persulfuric acid solution in which the persulfate ion concentration is increased in an electrolytic reaction has a relatively low temperature and cannot obtain sufficient oxidizing power due to self-decomposition of persulfuric acid. On the other hand, it is conceivable to heat a high-concentration persulfate solution and supply it to the use side. However, if it takes time, the self-decomposition of persulfate ions proceeds before use, and the persulfate ion concentration decreases. End up. For this reason, in the present invention, as a means for raising the temperature of the high-concentration persulfuric acid solution in a short time, a high-temperature solution containing 10-18 M of sulfate ions is mixed with the high-concentration persulfuric acid solution and heated in a short time. Is possible. The high-concentration persulfuric acid solution can be heated by the first persulfuric acid supply line heating means to a temperature of 80 ° C. or lower at which decomposition of persulfate ions does not proceed before mixing in order to reduce the load caused by the mixing. . As the first persulfuric acid supply line heating means, an appropriate heating device such as a heater or a heat exchanger can be used.

As a high-temperature solution containing sulfate ions to be mixed with the high-concentration persulfuric acid solution, it is collected after the persulfate ion concentration is lowered by using a solution that contains sulfate ions newly supplied from outside the system or on the persulfate-use side. A heated recovered solution can be used. These solutions may be supplied by being branched from the same supply source as the electrolyte to be used (supplied) in the electrolytic reaction apparatus.
A high-temperature solution containing sulfate ions can be supplied through a high-temperature sulfuric acid solution supply line, and is preferably heated to 130 to 200 ° C. by high-temperature sulfuric acid solution supply line heating means such as a heater provided in the line. Mix in concentrated persulfate solution. In addition, the sulfuric acid concentration in the high-temperature solution containing sulfate ions is required to be 10 to 18 M from the viewpoint of cleaning ability, and it is desirable to have a sulfate ion concentration equivalent to the solution used for electrolysis.
The mixing ratio of the high-concentration persulfuric acid solution and the high-temperature solution containing sulfate ions is preferably 1:10 to 1: 1. By mixing the two liquids under these conditions, a cleaning liquid having a prescribed solution temperature, sulfate ion concentration, and persulfate ion concentration can be reliably produced.

The high-temperature high-concentration persulfuric acid solution obtained by the above mixing becomes a temperature of 100 to 190 ° C. as a result of mixing. This high-temperature high-concentration persulfuric acid solution may be supplied as it is to the persulfuric acid use side, and can be further heated by a second persulfuric acid supply line heating means such as a heater provided in the persulfuric acid supply line. For example, in the single-wafer type using a jet cleaning liquid in which use of a high-temperature solution is particularly desirable, it is desirable that the heating means be heated to 150 to 190 ° C. and supplied to the persulfuric acid use side.
The appropriate temperature of the cleaning liquid can be 100 ° C. to 190 ° C. Below this temperature range, the effect of stripping and cleaning with persulfuric acid decreases. On the other hand, if the temperature exceeds 200 ° C., the cleaning liquid will boil and the resist cannot be sufficiently oxidized, and there is a problem of danger due to sulfuric acid mist, so the appropriate temperature of the cleaning liquid is within the above range. It is desirable to set the sulfate ion concentration so that the boiling point is higher than the temperature of the cleaning solution so that the cleaning solution does not boil.

  In the cleaning section, which is an example of the persulfuric acid use side, the cleaning material is effectively cleaned by cleaning the cleaning material with a high-temperature sulfuric acid solution containing high-concentration persulfate ions. Contaminants are effectively stripped and removed. The contaminants peeled off are transferred into the sulfuric acid solution, and are effectively decomposed by the oxidizing power when persulfate ions are self-decomposed. The cleaning unit may be either a single wafer type or a batch type, and the configuration on the use side is not limited to a specific one in the present invention. In the cleaning section, the cleaning liquid can be stored in the cleaning tank and the material to be cleaned can be immersed in the cleaning, and the cleaning liquid or a jet thereof can be applied to the material to be cleaned for cleaning. The jet can be formed as it is, or by a jet forming apparatus that mixes the cleaning liquid and a gas. As the gas, for example, air, nitrogen, inert gas, or the like can be used. The specific configuration of the jet forming device is not limited to a specific one, and a known one can be used. According to the cleaning by the jet flow, the required persulfuric acid solution can be made in a small amount, and reattachment of the peeled resist or the like can be prevented. In this jet cleaning, the cleaning effect is significantly improved by using a cleaning liquid having a high persulfate ion concentration.

  In the cleaning section, the persulfate ion concentration gradually decreases due to the self-decomposition of the persulfate ions in the solution. This persulfate ion-containing solution can be recovered as described above and returned to the electrolytic reaction apparatus as an electrolytic solution to regenerate persulfate ions. Further, the solution used for washing can be subjected to treatment such as drainage without returning to the persulfuric acid supply system.

  As described above, according to the method for producing a high-temperature and high-concentration persulfuric acid solution of the present invention, from the sulfate ions contained in the solution by repeatedly performing an electrolytic reaction while circulating a solution containing sulfate ions at a concentration of 10 to 18M. When producing a high concentration persulfate solution by generating persulfate ions and supplying the high concentration persulfate solution to the persulfuric acid use side, sulfate ions are added to the high concentration persulfate solution at a concentration of 10 to 18M. Since a high-temperature high-concentration persulfuric acid solution is mixed to produce a high-concentration persulfate solution, a high-concentration persulfate solution is produced by repeated electrolysis even when a solution containing 10 to 18 M high-concentration sulfate ions is used as electrolysis. Can do. In addition, by adjusting the solution containing sulfate ions to be subjected to the electrolytic reaction to a low temperature in advance, the electrolytic efficiency is further increased, the amount of persulfuric acid generated is increased, and the temperature of the electrolytic solution after electrolytic treatment is kept low. Persulfuric acid autolysis can be prevented and can be increased and maintained at higher persulfate concentrations.

  Furthermore, since the high-concentration persulfuric acid solution is instantaneously heated by mixing the high-concentration persulfuric acid solution obtained as described above with a high-temperature sulfuric acid solution immediately before the use of persulfuric acid such as a cleaning device, The problem that the persulfuric acid concentration decreases due to the self-decomposition of persulfuric acid by the time it reaches the use side is eliminated, and the cleaning material is effectively cleaned with a cleaning liquid having a high cleaning capacity. it can.

  In addition, if the solution used for the electrolytic reaction and the high-temperature solution containing sulfate ions have the same sulfate ion concentration, the sulfate ion concentration can be increased even when the high-temperature persulfate solution is mixed with the high-temperature solution. Therefore, there is no need to adjust the sulfate ion concentration by mixing a large amount of a high-temperature solution, and the mixing amount and mixing ratio can be easily set considering only the temperature adjustment. In addition, as an equivalent sulfate ion density | concentration, what has a density | concentration difference of 2 M or less can be illustrated.

  In addition, according to the apparatus for producing a high-temperature high-concentration persulfuric acid solution of the present invention, an electrolytic reaction device for producing persulfate ions from sulfate ions contained in the solution at a concentration of 10 to 18 M by electrolytic reaction, and the sulfate ions are included. A storage tank for storing the solution, a circulation line for transferring the solution from the storage tank as an electrolytic solution to the electrolytic reaction apparatus, and for transferring the solution electrolyzed from the electrolytic reaction apparatus to the storage tank, and the electrolytic reaction A persulfuric acid supply line for supplying a high-concentration persulfate solution containing persulfate ions generated by the apparatus to the persulfuric acid use side, and a high-temperature solution containing sulfate ions at a concentration of 10 to 18 M are supplied to the persulfuric acid supply line. A high-temperature sulfuric acid solution supply line that mixes with the solution containing the persulfate ions, so that electrolysis is performed while circulating the electrolyte solution between the storage tank and the electrolytic reaction tank, and the persulfate ion in the solution. The concentration can be made sufficiently high, and the solution containing the persulfate ions can be supplied to the use side through the persulfate supply line, and the hot sulfuric acid solution is mixed into the persulfate supply line through the high-temperature sulfuric acid solution supply line to instantly In addition, a high-temperature high-concentration persulfuric acid solution can be obtained. Moreover, the sulfuric acid density | concentration of both solutions can be made equivalent by making the supply source of the solution used for an electrolytic reaction, and the hot solution containing a sulfate ion the same.

(Embodiment 1)
Below, one Embodiment of this invention is described based on FIG.
The apparatus for producing a high-temperature high-concentration persulfuric acid solution according to this embodiment includes a persulfuric acid supply system 10 that produces persulfuric acid by an electrolytic reaction. First, the configuration of the persulfuric acid supply system 10 will be described with reference to FIG. To do.
The persulfuric acid supply system 10 includes a storage tank 1 that stores a concentrated sulfuric acid solution as an electrolytic solution, and a feed pipe 2a and a return pipe 2b of a circulation line are connected to the storage tank 1, and the feed pipe 2a. Is provided with a liquid feed pump 3 for feeding the electrolyte solution. On the downstream side of the liquid feed pump 3, a cooler 4 for cooling the liquid electrolyte to be fed is interposed as a liquid electrolyte cooling means. On the downstream side, the feed pipe 2 a is connected to the inlet side of the electrolytic reaction tank 5. In addition, you may comprise the said cooler so that it may provide in the return pipe 2b side and may cool the electrolyte solution sent by the exit side of the electrolytic reaction tank 5. FIG.

  In the electrolytic reaction tank 5, an anode 5a and a cathode 5b are disposed, and a bipolar electrode 5c is disposed between the anode 5a and the cathode 5b. Note that the present invention is not limited to the bipolar type, and may include only an anode and a cathode as electrodes. A DC power source 6 is connected to the anode 5a and the cathode 5b, thereby enabling DC electrolysis in the electrolytic reaction tank 5.

The electrolytic reaction tank 5 is configured such that a solution passes between the electrodes, and the return pipe 2 b is connected to the outlet side of the electrolytic reaction tank 5. In this embodiment, the electrodes 5a, 5b, 5c are constituted by diamond electrodes. The diamond electrode is manufactured by forming a diamond thin film on a substrate and doping boron in a range of preferably 50 to 20,000 ppm with respect to the carbon content of the diamond thin film. In addition, the substrate may be removed to form a self-supporting type after the thin film is formed.
The electrolytic reaction tank 5 and the DC power source 6 constitute the electrolytic reaction apparatus of the present invention.

  The return pipe 2b connected to the outlet side of the electrolytic reaction tank 5 is connected to the storage tank 1, and the solution circulates between the storage tank 1 and the electrolytic reaction tank 5 by the feed pipe 2a and the return pipe 2b. Is configured to do. The storage tank 1 is connected to a persulfuric acid supply line 7 for supplying the electrolyzed solution to the cleaning tank 20 on the persulfuric acid use side. The persulfuric acid supply line 7 is provided with an on-off valve 7a. It is installed. Furthermore, a replenishment line 8 for replenishing an electrolyte to be electrolyzed in the electrolytic reaction apparatus is connected to the storage tank 1 via an on-off valve 8a. The persulfuric acid supply system 10 is configured as described above.

The persulfuric acid supply line 7 is connected to a persulfuric acid use side (not shown) via a liquid feed pump 11 and a heater 12 corresponding to the first persulfuric acid supply line heating means on the downstream side. In the persulfuric acid supply line 7, the high-temperature sulfuric acid solution supply line 13 is joined at the downstream side of the heater 12 and at the upstream side B portion on the persulfuric acid use side. The high-temperature sulfuric acid solution supply line 13 is provided with a heater 14 corresponding to a high-temperature sulfuric acid solution supply line heating unit. The high temperature persulfuric acid solution supply line 13 is configured to supply a sulfuric acid solution having a sulfate ion concentration difference of 2 M or less from the high concentration persulfuric acid solution supplied through the persulfuric acid supply line. As the sulfuric acid solution, there can be used a solution containing sulfate ions newly supplied from outside the system or a recovered solution recovered after the persulfate ion concentration is decreased on the persulfuric acid use side.
In addition, the replenishment line 8 provided in the persulfuric acid supply system 10 is recovered after the persulfate ion concentration is lowered by using a solution containing sulfate ions or a persulfate use side that is newly supplied from outside the system. The recovered solution is supplied, and a cooler 9 is interposed in the line 8.

The operation of the above embodiment will be described below.
On the persulfuric acid supply system 10 side, a sulfuric acid solution having a concentration of 10 to 18 M (14.5 M in this embodiment) is accommodated in the storage tank 1. The solution in the storage tank 1 is sequentially sent to the electrolytic reaction tank 5 by the liquid feed pump 3 through the feed pipe 2a. At this time, the solution is preferably cooled to about 40 ° C. by the cooler 4. In the electrolytic reaction tank 5, the DC power source 6 is energized between the anode 5 a and the cathode 5 b. By this energization, the bipolar electrode 5c is polarized and an anode and a cathode appear. The solution sent to the electrolytic reaction tank 5 is passed between these electrodes. At this time, it is desirable to set the output of the liquid feed pump 3 so that the liquid flow rate is 1 to 10,000 m / hr. In the above energization, it is desirable to control the energization so that the current density on the diamond electrode surface is 10 to 100,000 A / m ² .

  When the solution is energized in the electrolytic reaction tank 5, the sulfate ions in the solution undergo an oxidation reaction to generate persulfate ions, thereby obtaining a sulfuric acid solution containing a high concentration of persulfate ions. The sulfuric acid solution containing the persulfate ions is stored in the storage tank 1 through the return pipe 2b. Although the sulfuric acid solution containing persulfate ions stored in the storage tank 1 is heated to 40 to 60 ° C. by the electrolysis, it does not reach a temperature at which self-decomposition of persulfate ions is particularly promoted. The solution in the storage tank 1 is further cooled to about 40 ° C. by the cooler 4 while being fed by the pump 3 through the feed pipe 2a, and then introduced again into the electrolytic reaction tank 5 and electrolyzed in the same manner as described above. Persulfate ions are generated to increase the concentration of persulfate ions, and then transferred to the storage tank 1 through the return pipe 2b. By repeating the above operation, the concentration of persulfate ions in the concentrated sulfuric acid solution increases further, and it becomes possible to obtain a high concentration of persulfate ions such as 50 to 150 g / L in the concentrated sulfuric acid solution.

After the persulfate ion concentration becomes sufficiently high, the on-off valve 7a is opened while continuing the electrolysis, and a concentrated sulfuric acid solution containing persulfate ions (high concentration persulfate solution) is supplied to the persulfate supply line 7. In the present invention, it is also possible to stop the electrolysis in the electrolytic cell 5 and supply the high-concentration persulfuric acid solution.
In the persulfuric acid supply line 7, the high-concentration persulfuric acid solution is fed by the liquid feed pump 11, and is preferably heated by the heater 12 at a temperature at which the self-decomposition rate of persulfuric acid does not become very high, for example, 70 ° C. or less (this In the embodiment, the temperature is raised to 60 ° C. However, this heating can be omitted.
The high-concentration persulfuric acid solution transferred in the persulfuric acid supply line 7 is transferred to the persulfuric acid use side. At this time, the high temperature supplied from the high-temperature sulfuric acid solution supply line 13 at the downstream portion B of the heater 12. With sulfuric acid solution. In the mixing of the high-concentration persulfuric acid solution and the high-temperature sulfuric acid solution, the volume mixing ratio is desirably 1:10 to 1: 1. When this high-concentration persulfuric acid solution and a high-temperature (preferably 130 to 200 ° C.) solution are merged in the persulfuric acid supply line 7, the solution is instantaneously preferably heated to 100 to 190 ° C. The sulfuric acid solution is supplied to the persulfuric acid use side.

  Moreover, the electrolyte solution reduced in volume by supplying to the high-concentration persulfuric acid solution is directly supplied to the storage tank 1 and the circulation lines 2a and 2b from the replenishment line 8 as necessary. Further, the replenishment line 8 may be connected to the entrance side of the electrolytic reaction tank 5 without being connected to the storage tank 1 or instead of (or in addition to) the storage tank 1 or the circulation lines 2a and 2b. . In this case, a replenishment storage tank may be separately provided, the electrolyte solution to be replenished in the supply storage tank may be stored, and the electrolyte solution may be joined from the supply storage tank to the feed pipe 2a. . Further, another storage tank may be connected to the storage tank 1 in series, and the electrolytic solution may be supplied to the other storage tank. Then, the electrolytic solution may be sent from the other storage tank to the electrolytic reaction tank 5 through the feed pipe 2a.

(Embodiment 2)
Next, an embodiment in which a cleaning unit is connected as the persulfuric acid use side will be described with reference to FIG. In addition, about the structure similar to the said embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted or simplified.

The persulfuric acid supply line 7 of the persulfuric acid supply system 10 passes through the liquid feed pump 22 and, on the downstream side thereof, a washing tank on the persulfuric acid use side via a heater 23 corresponding to the first persulfuric acid supply line heating means. 20 is connected.
A heater 21 for heating the stored cleaning liquid is provided in the cleaning tank 20. Further, a feed pipe 26 having an SS removal filter 25 and a pump 27 interposed is connected to the washing tank 20 on the drain side, and the feed pipe 26 is a portion A downstream of the pump 27 and the persulfuric acid supply system. Ten replenishment lines 8 and a reflux pipe 28 corresponding to a high-temperature sulfuric acid solution supply line are branched and connected. The reflux pipe 28 is provided with a heater 29 corresponding to a high-temperature sulfuric acid solution supply line heating means. Further, the reflux pipe 28 joins the persulfuric acid supply line 7 on the downstream side of the heater 23 and on the upstream side B portion of the cleaning tank 20.

Next, the operation of the above embodiment will be described.
On the persulfuric acid supply system 10 side, a sulfuric acid solution having a concentration of 10 to 18 M (14.5 M in this embodiment) is accommodated in the storage tank 1, and the electrolytic reaction tank 5 is sequentially passed through the feed pipe 2 a by the liquid feed pump 3. To liquid. At this time, the solution is preferably cooled to about 40 ° C. by the cooler 4. In the electrolytic reaction tank 5, an electrolytic reaction is performed in the same manner as in the above embodiment, and a sulfuric acid solution containing a high concentration of persulfate ions is obtained.

After the persulfate ion concentration becomes sufficiently high, the on-off valve 7a is opened while continuing the electrolysis, and a concentrated sulfuric acid solution containing persulfate ions (high concentration persulfate solution) is supplied to the persulfate supply line 7.
The high-concentration persulfuric acid solution transferred in the persulfuric acid supply line 7 is transferred to the washing tank 20 side and accumulated. At this time, the high temperature supplied from the reflux pipe 28 at the downstream portion B of the heater 23. With sulfuric acid solution. The solution is obtained by collecting a cleaning solution containing persulfate ions and sulfate ions accumulated in the cleaning tank 20, and the concentration of persulfate ions is reduced from the beginning due to autolysis. This recovered solution is fed by the pump 27 through the feed pipe 26. Note that the entire amount of the recovered solution transferred through the feed pipe 26 is sent to the reflux pipe 28 during cleaning. Further, the present invention may be configured such that a small amount of the recovered solution transferred through the feed pipe 26 is sent to the replenishment line 8 and the remainder is sent to the reflux pipe 28. In the mixing of the high-concentration persulfuric acid solution and the high-temperature sulfuric acid solution, the volume mixing ratio is desirably 1: 3 to 1: 5.

The cleaning liquid is preferably maintained at 130 to 150 ° C. in the cleaning tank 20 by the operation of the heater 21. After being collected, the cleaning liquid is preferably 130 to 200 ° C. by a heater 29 interposed in the reflux pipe 28. (In this embodiment, about 150 ° C.). When this high-temperature cleaning liquid and a solution containing persulfate ions are merged in the persulfuric acid supply line 7, the solution instantaneously preferably becomes 100 to 150 ° C. (about 140 ° C. in this embodiment) and enters the cleaning tank 20. be introduced. Moreover, as a result of mixing, the persulfate ion concentration of the high-temperature high-concentration persulfate solution is about 16 g / L.
In the cleaning tank 20, the high-temperature high-concentration persulfuric acid solution is gradually accumulated as a cleaning liquid. At this time, in the cleaning tank 20, the solution temperature in the tank is preferably maintained at 100 to 190 ° C. (about 150 ° C. in this embodiment) by the heater 21.

  In the cleaning tank 20, the semiconductor substrate 100 as a material to be cleaned is immersed in the cleaning liquid while being held by the substrate holder 101 or the like. In the cleaning tank 1, resist residues and the like on the surface of the semiconductor substrate 100 are peeled and removed by the action of a high concentration and high temperature sulfuric acid solution containing persulfate ions at a high concentration, and transferred to the sulfuric acid solution as a contaminant, Dissolve. The dissolved resist is further decomposed by the oxidizing power of persulfate ions that undergo autolysis. As described above, the cleaned cleaning liquid is sequentially transferred by the feed pipe 26, and SS that cannot be decomposed is removed by the SS removal filter 25. The recovered cleaning liquid is sent to the reflux pipe 28 by the liquid feeding pump 27 as described above, and the recovered liquid whose temperature has been lowered by the liquid feeding is heated to about 150 ° C. by the heater 29 and transferred through the persulfuric acid supply line 7. Mix in a high concentration persulfate solution.

If the cleaning is continued for 30 seconds to several minutes, the surface of the semiconductor substrate 100 is effectively cleaned, so that the cleaning process is terminated, and the supply of the high-concentration persulfuric acid solution from the persulfuric acid supply system 10 is stopped. A solution having a reduced persulfate ion concentration in the cleaning tank 20 is supplied from the feed pipe 26 to the entire replenishment line 8. The supply amount at this time is an amount that compensates for the amount reduced by the supply of the high-concentration persulfuric acid solution to the cleaning tank 20 in the persulfuric acid supply system 10.
A small amount of the cleaning liquid transferred to the replenishment line 8 is cooled to about 40 ° C. by the cooler 9 and then directly supplied to the storage tank 1 or the electrolytic reaction tank 5 of the persulfuric acid supply system 10 as an electrolytic solution. At this time, it is desirable to generate persulfate ions in the electrolytic reaction tank 5 while electrolysis continues.

In the present invention, the electrolyte solution may be supplied from the replenishment line 8 while supplying the high-concentration persulfuric acid solution. In that case, it is desirable to adjust the replenishment amount so that the persulfuric acid concentration of the solution supplied while continuing the electrolysis does not gradually decrease due to the replenishment.
Note that the concentrated sulfuric acid solution used for replenishment may be a concentrated sulfuric acid solution newly supplied from outside the system, or any of the recovered liquids recovered after persulfate ions are reduced by autolysis on the persulfuric acid use side. Good.

(Embodiment 3)
In the second embodiment, the cleaning unit including a batch type cleaning tank has been described. However, in the present invention, the cleaning liquid may be applied to a single wafer cleaning unit. Below, the usage example provided with a jet forming apparatus as one Embodiment is demonstrated based on FIG. In addition, the same code | symbol is attached | subjected about the structure similar to the said embodiment, and the description is abbreviate | omitted or simplified.

The persulfuric acid supply line 7 of the persulfuric acid supply system 10 passes through a liquid feed pump 31, a heater 32 corresponding to the first persulfuric acid supply line heating means, and an infrared heater 33 corresponding to the second persulfuric acid supply line heating means. Connected to the cleaning section.
In the cleaning section, a nozzle 34 is provided as a jet forming device, and the tip side ejection section of the nozzle 34 is located in the cleaning tank 30. The nozzle 34 is configured to eject a jet of concentrated sulfuric acid solution containing persulfate ions supplied from the persulfuric acid supply line 7 downward.
Further, a substrate mounting table 102 is installed in the cleaning tank 30 in the ejection direction of the nozzles 34, and the semiconductor substrate 100, which is a material to be cleaned, is mounted on the substrate mounting table 102. It is desirable that the substrate mounting table 102 or the nozzle 34 is relatively movable so that the jet flows uniformly on the surface of the semiconductor substrate 100. In the cleaning liquid drainage part of the cleaning tank 30, a recovery pipe 35 is connected, and the recovery pipe 35 is connected to a recovery storage tank 36. A feed pipe 38 is connected to the collection storage tank 36 via an SS removal filter 37 and a liquid feed pump 39, and the feed pipe 38 is a portion A on the downstream side of the liquid feed pump 39. And a reflux pipe 40 corresponding to a high-temperature sulfuric acid solution supply line. A heater 41 corresponding to a high-temperature sulfuric acid solution supply line heating unit is interposed in the reflux pipe 40. Further, the reflux pipe 40 joins at a portion B of the persulfuric acid supply line 7 downstream of the heater 32 and upstream of the infrared heater 33. The replenishment line 8 is provided with a cooler 9.

Next, the operation of the single wafer cleaning system configured as described above will be described.
The concentrated sulfuric acid solution containing a high concentration of persulfate ions generated by the persulfuric acid supply system 10 is transferred to the washing tank 30 side through the persulfuric acid supply line 7 by the liquid feed pump 31 and supplied to the nozzle 34. At this time, the solution is heated to a temperature at which the self-decomposition rate of persulfuric acid does not become very high, for example, 50 to 60 ° C., on the upstream side of the persulfuric acid supply line 7. However, this heating configuration can be omitted. Further, the concentrated sulfuric acid solution containing persulfate ions at a high concentration is transferred to the washing tank 30 side and used for washing. At that time, the solution is sent through the reflux pipe 40 at the downstream portion B of the heater 32. Mixed with hot cleaning solution. The cleaning liquid is a solution containing persulfate ions and sulfate ions recovered in the cleaning tank 30, recovered in the recovery pipe 35, temporarily stored in the recovery storage tank 36, and then sent through the feed pipe 38 by the pump 39. To be liquidated. Note that the entire amount of the cleaning liquid transferred through the feed pipe 38 is sent to the reflux pipe 40 during cleaning. Further, the present invention may be configured such that a small amount of the cleaning liquid transferred through the feed pipe 38 is sent to the replenishment line 8 and the remainder is sent to the reflux pipe 40. In mixing the high-concentration persulfuric acid solution and the high-temperature sulfuric acid solution, it is desirable that the volume mixing ratio is 1: 1 to 1: 3.

The cleaning liquid is preferably used at a temperature of 150 to 190 ° C. (about 170 ° C. in this embodiment) in the cleaning tank 30, and the temperature lowered to the reflux pipe 40 is suitably adjusted by the heater 41. Is raised to 150 to 190 ° C. (about 170 ° C. in this embodiment). When this high-temperature cleaning solution and a solution containing persulfate ions are combined in the persulfuric acid supply line 7, the solution instantaneously preferably has a temperature of 100 to 150 ° C. (in this embodiment, about 130 ° C.). Moreover, as a result of mixing, the persulfate ion concentration of the high-temperature high-concentration persulfate solution is about 30 g / L.
Furthermore, the high-temperature high-concentration persulfuric acid solution is preferably heated to 150 to 190 ° C. (about 170 ° C. in this embodiment) by the infrared heater 33 and supplied to the cleaning tank 30.

  In the washing tank 30, a high-temperature concentrated sulfuric acid solution containing high-concentration persulfate ions is jetted at the nozzle 34 and ejected for a certain period of time. The substrate 100 is set on the substrate mounting table 102, and the substrate 100 is rotated by the substrate mounting table 102. The surface of the rotating substrate 100 is evenly cleaned by the jet flow, and the resist and the like are peeled off and removed. The sprayed cleaning liquid scatters and drops after cleaning the substrate 100, and is successively discharged from the cleaning tank 30 through the recovery pipe 35 while decomposing the resist melt, and is accumulated in the recovery storage tank 36. The concentration of persulfate ions in the solution gradually decreases due to autolysis. The high-temperature concentrated sulfuric acid solution accumulated in the collection reservoir 36 is sequentially transferred through the feed pipe 38 by the liquid feed pump 39, and the SS contained in the solution is removed by the SS removal filter 37. The recovered cleaning liquid is sent to the reflux pipe 40 by the liquid feeding pump 39 as described above, and the recovered liquid whose temperature has been lowered by the liquid feeding is heated to about 170 ° C. by the heater 41 and transferred through the persulfuric acid supply line 7. Mix in a high concentration persulfate solution.

  When the cleaning is completed, the supply of the high-concentration persulfuric acid solution from the persulfuric acid supply system 10 is stopped, and the entire amount of the solution in the cleaning tank 20 is supplied from the feed pipe 38 to the replenishment line 8. The supply amount at this time is an amount that compensates for the amount reduced by the supply of the high-concentration persulfate solution to the washing tank 30 in the persulfuric acid supply system 10. A small amount of the cleaning liquid transferred to the replenishment line 8 is cooled to about 40 ° C. by the cooler 9 and then directly supplied to the storage tank 1 or the electrolytic reaction tank 5 of the persulfuric acid supply system 10 as an electrolytic solution. Also at this time, it is desirable to generate persulfate ions in the electrolytic reaction tank 5 while electrolysis continues.

  In the present invention, the electrolyte solution may be supplied from the replenishment line 8 while supplying the high-concentration persulfuric acid solution. In that case, it is desirable to adjust the replenishment amount so that the persulfuric acid concentration of the solution supplied while continuing the electrolysis does not gradually decrease due to the replenishment.

(Embodiment 4)
In the above-described embodiment, the high temperature sulfuric acid solution is obtained from the solution collected in the cleaning tank for those equipped with a batch type cleaning tank as the cleaning unit. However, as the present invention, the high temperature sulfuric acid solution is supplied from outside the system. It may be. Below, this embodiment is described based on FIG. In addition, the same code | symbol is attached | subjected about the structure similar to each said embodiment, and the description is abbreviate | omitted or simplified.

The persulfuric acid supply line 7 of the persulfuric acid supply system 10 is joined to the high-temperature sulfuric acid solution supply line 50 at a downstream portion B thereof via a liquid feed pump 31 and a heater 32 corresponding to the first persulfuric acid supply line heating means. Furthermore, it is connected to the cleaning section via an infrared heater 33 corresponding to the second persulfuric acid supply line heating means. The high-temperature sulfuric acid solution supply line 50 is connected to the sulfuric acid storage tank 51, and the high-temperature sulfuric acid solution supply line 50 is provided with a heater 52 as high-temperature sulfuric acid solution supply line heating means. A replenishment line 8 is connected to the sulfuric acid storage tank 51, and a sulfuric acid solution can be supplied from the sulfuric acid storage tank 51 to the replenishment line 8 and the high-temperature sulfuric acid solution supply line 50, respectively.
In the cleaning section, a nozzle 34 is provided as a jet forming device, and the tip-side ejection section of the nozzle 34 is located in the cleaning tank 30. Further, the cleaning liquid draining section of the cleaning tank 30 is configured such that the cleaning liquid used for cleaning is drained without being sent to the persulfuric acid supply system.

Next, the operation of the single wafer cleaning system configured as described above will be described.
In the sulfuric acid storage tank 51, sulfuric acid having a sulfuric acid concentration of 10 to 18M (14.5M in this embodiment) is stored and supplied to the persulfuric acid supply system 10 to generate persulfate ions by an electrolytic reaction. The concentrated sulfuric acid solution produced in the persulfuric acid supply system 10 and containing persulfate ions at a high concentration is transferred to the cleaning tank 30 side through the persulfuric acid supply line 7 by the liquid feed pump 31 and supplied to the nozzle 34 side. . At this time, the solution is heated by the heater 32 to a temperature at which the self-decomposition rate of persulfuric acid does not become very high, for example, 50 to 60 ° C. However, this heating configuration can be omitted. Further, the concentrated sulfuric acid solution containing persulfate ions at a high concentration is mixed with the high-temperature high-concentration sulfuric acid solution supplied from the high-temperature sulfuric acid solution supply line 33 in the part B of the persulfuric acid supply line 7 to instantaneously reach about 130 ° C. Heated. In the mixing of the high-concentration persulfuric acid solution and the high-temperature sulfuric acid solution, the volume mixing ratio is 1: 2. In the high-temperature sulfuric acid solution supply line 33, normal temperature sulfuric acid stored in the sulfuric acid storage tank 51 is heated to 170 ° C. by the heater 52 and supplied. The high-temperature high-concentration persulfuric acid solution obtained by the above mixing in part B is further heated to about 170 ° C. by the infrared heater 33 and then supplied to the nozzle 34.

In the cleaning tank 30, a high-temperature concentrated sulfuric acid solution containing persulfate ions is jetted at the nozzle 34 and ejected for a certain period of time, and the substrate 100 placed on the substrate mounting table 102 is washed evenly, and the resist is peeled off. Remove. The sprayed cleaning liquid scatters and drops after the substrate 100 is cleaned, and is successively discharged from the cleaning tank 30 while decomposing the dissolved resist.
On the other hand, in the persulfuric acid supply system 10, when the concentrated sulfuric acid solution containing the electrolyzed persulfate ions is insufficient, the persulfuric acid storage is preferably performed while the persulfuric acid supply line 7 is stopped and then the electrolysis is preferably continued. A high-concentration sulfuric acid solution at room temperature, which is a new solution, is supplied from the tank 51 through the supply line 8 as an electrolyte. This electrolytic solution can be electrolyzed in an electrolytic reaction device provided in the persulfuric acid supply line 10 and supplied as a cleaning liquid from the persulfuric acid supply line 7 to the cleaning tank 30. In the present invention, the electrolytic solution may be replenished through the sulfuric acid storage tank 51 while the high-concentration persulfuric acid solution is supplied through the persulfuric acid supply line 7.

  As described above, the present invention has been described based on each of the above embodiments.In particular, when a high concentration persulfuric acid solution is generated and used from high concentration sulfuric acid, and the waste liquid is collected and reused as an electrolyte, Although the electrolysis efficiency is low due to the high concentration of sulfuric acid, if the current efficiency is increased, a large amount of gas is generated and the electrolysis efficiency cannot be increased. Therefore, as in the present invention, it is an indispensable technique to carry out electrolysis while circulating sulfuric acid to increase the concentration of persulfuric acid. Further, the present invention is not limited to the description of the above embodiment, and appropriate modifications can be made without departing from the scope of the present invention.

Hereinafter, examples using the sulfuric acid recycling type single wafer cleaning system of the fourth embodiment will be described.
A high-concentration sulfuric acid solution (14.8M) prepared in a ratio of 40 liters of 98% concentrated sulfuric acid and 10 liters of ultrapure water was accommodated in the storage tank. In the electrolytic reaction apparatus, two electrolytic reaction tanks each incorporating 10 boron-doped conductive diamond electrodes having a diameter of 15 cm and a thickness of 0.5 mm were arranged in series. Effective anode area for electrolysis is 30dm ^2, and electrolysis by setting the current density 30A / dm ^2. At this time, in the electrolytic reaction apparatus, it was confirmed that the persulfuric acid production rate was 3 g / l / hr. By continuing the electrolysis while circulating the solution between the storage tank and the electrolytic reactor, the concentration of persulfuric acid in the solution reached 50 g / L.
The solution containing persulfuric acid in the storage tank was used as a cleaning liquid in a single wafer cleaning apparatus at 500 ml / min. In the middle of this, the mixture was heated to about 70 ° C. with a heater, mixed with a high-temperature high-concentration sulfuric acid solution (14.8M), heated to about 170 ° C., and introduced into the nozzle. A 5-inch silicon wafer with a resist held on the substrate mounting table was added for 2 min. / Washed at a rate of about 1 sheet. The waste liquid was collected in a collection tank. This process was performed continuously for 3 hours, and 60 clean wafers could be obtained. During this time, no new chemical was added, and the TOC concentration of the cleaning liquid in the recovery tank was below the detection limit.

(Comparative Example 1)
The single wafer cleaning apparatus of Example 1 was used, and a cleaning liquid heated to 170 ° C. was mixed with sulfuric acid: hydrogen peroxide solution at a ratio of 4: 1. A 5-inch silicon wafer with a resist is added for 2 min. / Washed at a rate of about 1 sheet. After 3 hours, 60 clean wafers could be obtained, but about 27 L of cleaning waste liquid was generated.

It is the schematic which shows the production | generation apparatus of the high temperature high concentration persulfuric acid solution of this invention. It is the schematic which shows one Embodiment of the persulfuric acid supply system contained in the production | generation apparatus of the high temperature high concentration persulfuric acid solution of this invention. It is the schematic which shows one Embodiment of this invention. Similarly, it is the schematic which shows other embodiment. Similarly, it is the schematic which shows other embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Storage tank 2a Feed pipe 2b Return pipe 4 Cooler 5 Electrolysis reaction tank 5a Anode 5b Cathode 5c Bipolar electrode 6 DC power supply 7 Persulfuric acid supply line 8 Replenishment line 9 Cooler 10 Persulfuric acid supply system 12 Heater 13 High-temperature sulfuric acid solution supply line DESCRIPTION OF SYMBOLS 14 Heater 20 Washing tank 23 Heater 26 Feeding pipe 28 Reflux pipe 29 Heater 30 Washing tank 32 Heater 33 Infrared heater 34 Nozzle 35 Collection pipe 36 Collection storage tank 38 Feed pipe 40 Reflux pipe 41 Heater 50 High-temperature sulfuric acid solution supply line 51 Sulfuric acid storage tank 52 Heater

Claims (14)

By repeatedly conducting an electrolytic reaction while circulating a solution containing sulfate ions at a concentration of 10 to 18M, persulfate ions are generated from sulfate ions contained in the solution, and the concentration of persulfate ions is higher than that before the electrolysis. When the high-concentration persulfuric acid solution is manufactured and supplied to the persulfuric acid use side, the high-concentration persulfuric acid solution contains sulfate ions at a concentration of 10 to 18 M , and the electrolytic reaction is performed. The concentration of the solution to be provided is equal to the concentration of the sulfate ion, and the difference in concentration is 2M or less, and the solution having a temperature higher than that of the high-temperature persulfate solution is mixed to have a temperature higher than that of the high-concentration persulfate solution before mixing. A method for producing a high-temperature high-concentration persulfuric acid solution, characterized by using a high-temperature high-concentration persulfuric acid solution. The high-temperature solution containing the sulfate ion is heated from the solution containing the sulfate ion newly supplied from outside the system or the recovered solution recovered after the concentration of the persulfate ion is decreased on the persulfuric acid use side. The method for producing a high-temperature high-concentration persulfuric acid solution according to claim 1, wherein By repeatedly conducting an electrolytic reaction while circulating a solution containing sulfate ions at a concentration of 10 to 18M, persulfate ions are generated from sulfate ions contained in the solution, and the concentration of persulfate ions is higher than that before the electrolysis. When the high concentration persulfuric acid solution is manufactured and supplied to the persulfuric acid use side, the high concentration persulfuric acid solution contains sulfate ions at a concentration of 10 to 18 M, and the high temperature persulfuric acid solution A solution having a temperature higher than that of the solution, which is used on the persulfuric acid use side and the recovered solution recovered after the persulfate ion concentration is lowered is mixed with the heated high-persulfate solution before mixing. A method for producing a high-temperature high-concentration persulfuric acid solution, characterized in that a high-temperature high-concentration persulfuric acid solution having a high temperature is used.   The high-temperature high-concentration persulfate solution according to any one of claims 1 to 3, further comprising heating the high-temperature high-concentration persulfate solution obtained by mixing a high-temperature solution containing sulfate ions with the high-concentration persulfate solution. Generation method.   The method for producing a high-temperature high-concentration persulfuric acid solution according to any one of claims 1 to 4, wherein the temperature of the solution containing sulfate ions circulated in the electrolytic reaction is 10 to 70 ° C.   The method for producing a high-temperature high-concentration persulfuric acid solution according to any one of claims 1 to 5, wherein the temperature of the high-temperature solution containing sulfate ions is 130 to 200 ° C.   The high-temperature high-concentration persulfate solution according to any one of claims 1 to 6, wherein a mixing ratio between the high-concentration persulfate solution and a high-temperature solution containing sulfate ions is 1:10 to 1: 1. Generation method.   The method for producing a high-temperature high-concentration persulfuric acid solution according to any one of claims 1 to 7, wherein the temperature of the high-temperature high-concentration persulfuric acid solution supplied to the persulfuric acid use side is 100 to 190 ° C. . An electrolytic reaction device for generating persulfate ions from sulfate ions contained in a solution at a concentration of 10 to 18 M by an electrolytic reaction, a storage tank for storing the solution containing the sulfate ions, and the solution to be electrolyzed from the storage tank as was transferred to the electrolytic reaction apparatus, a circulation line for transporting a solution that is the electrolyte from the electrolytic reaction apparatus to the storage tank, the viewing containing persulfate ions produced by the electrolytic reaction apparatus, before performing the electrolysis persulfate supply line for supplying a high concentration persulfate solution persulfate consuming with increased persulfate ion concentration than the solution contains sulfate ions at a concentration of 10~18M to該過sulfuric acid supply line, the high concentration over An apparatus for producing a high-temperature high-concentration persulfuric acid solution, comprising: a high- temperature sulfuric acid solution supply line that supplies a solution having a temperature higher than that of the sulfuric acid solution and mixes the solution with the high-concentration persulfate solution.   The high-temperature high-concentration persulfuric acid solution according to claim 9, further comprising an electrolytic solution cooling means for cooling the electrolytic solution transferred to the electrolytic reaction device or the electrolytic solution transferred from the electrolytic reaction device. Generator.   As an electrolytic solution to be transferred to the electrolytic reaction apparatus, a solution containing sulfate ions newly supplied from outside the system or a recovered solution used after the persulfate ion concentration is reduced after being used on the persulfuric acid use side is used. The apparatus for producing a high-temperature high-concentration persulfuric acid solution according to claim 9 or 10, further comprising a replenishment line for replenishing.   The high-temperature sulfuric acid solution supply line is configured to supply a solution containing sulfate ions newly supplied from outside the system or a recovered solution that is used on the persulfuric acid use side and recovered after the persulfate ion concentration decreases. The apparatus for producing a high-temperature high-concentration persulfuric acid solution according to any one of claims 9 to 11, further comprising a high-temperature sulfuric acid solution supply line heating unit configured to heat the solution.   The persulfate supply line includes a first persulfate supply line heating means for heating the solution containing the persulfate ions before mixing the high-temperature solution containing the sulfate ions, and a solution containing the persulfate ions after the mixing. The apparatus for producing a high-temperature high-concentration persulfuric acid solution according to any one of claims 9 to 12, further comprising a second persulfuric acid supply line heating means for heating the persulfuric acid.   The apparatus for producing a high-temperature high-concentration persulfuric acid solution according to any one of claims 9 to 13, wherein the persulfuric acid use side is a cleaning system using persulfuric acid.

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