Method and treatment system for inhibiting the precipitation of copper nanoparticles from ultra-pure copper sulfate solution during storage

Abstract

The application discloses a method and a treatment system for inhibiting the precipitation of nano copper in a super-pure copper sulfate solution during storage. After electrolysis and terminal filtration of the super-pure copper sulfate solution are completed, before filling, a sample solution is obtained from an online flow path, and the concentration of cuprous ions in the sample solution is determined. According to the stoichiometric relationship between the concentration of cuprous ions, the volume of the solution to be treated, and hydrogen peroxide for oxidizing monovalent copper to divalent copper, the calculated amount of electronic-grade hydrogen peroxide is calculated according to the oxidation coefficient of cuprous equivalent. The calculated amount of electronic-grade hydrogen peroxide is injected into the flowing super-pure copper sulfate solution in sections, and the cuprous ions are oxidized to divalent copper ions through a residence reaction. The residual cuprous ions and residual hydrogen peroxide in the reacted solution are rechecked, and the solution is filled after passing the rechecking. The application changes the control object of particle growth during storage from exogenous particles to residual monovalent copper sources, and can reduce the risk of delayed precipitation of nano copper without introducing new metal impurities.

Description

Technical Field

[0001] This invention relates to the field of wet electronic chemicals and high-purity copper salt solution treatment technology, specifically to a method and treatment system for inhibiting the precipitation of nano-copper during the storage of ultrapure copper sulfate solution. Background Technology

[0002] In integrated circuit copper interconnect and advanced packaging electroplating processes, copper sulfate solution serves as both a source of copper ions and a crucial chemical in the electroplating bath replenishment system. Downstream customers typically focus on indicators such as metallic impurities, chloride ions, total organic carbon, acidity, copper content, and particle count. Among these, particle count significantly impacts the stability of fine interconnects, blind via filling, and high-density bump plating. For ultrapure copper sulfate solutions, factory inspections often demonstrate acceptable total elemental purity; however, after several weeks of storage, the submicron or nanoparticle count may still show a sustained increase.

[0003] These types of anomalies are not easily detected by routine elemental analysis. This is because the main component of the particles is still copper, and the total copper content in the solution remains almost constant within the testing error range. Retesting results for foreign metal impurities using ICP-MS or ICP-OES may still be within acceptable limits. If only external contamination is considered, the problem is easily attributed to container cleanliness, terminal filtration accuracy, or the filling environment. However, the possibility of valence state transformation within the solution itself forming metallic copper nuclei is often overlooked.

[0004] In the electrolytic preparation of high-purity copper sulfate or copper plating source solutions, copper anode dissolution, cathode side reactions, local mass transfer, and complexation environments can cause monovalent copper to exist in the system for a short period. Although the final product exists as divalent copper sulfate, trace amounts of cuprous ions may be introduced into the finished solution when acidity, oxygen content, and trace reducing conditions change. Cuprous ions are not always stable in aqueous solutions; their disproportionation reaction can generate metallic copper and divalent copper ions. For common chemicals, the change in copper content caused by this reaction is minimal. However, for electronic-grade copper sulfate, where particle counts are strictly controlled, even a small amount of metallic copper clusters can result in a continuous increase in particle count during storage.

[0005] Common approaches in current production control include improving terminal filtration accuracy, extending circulation filtration time, enhancing container cleaning, increasing raw material purity, or adding stabilizers to the electroplating solution. While each of these methods has its merits, for trace cuprous ions already dissolved in the finished product solution, terminal filtration can only remove existing particles and cannot eliminate precursors that continue to disproportionate and precipitate after storage. Container cleaning primarily targets exogenous particles and cannot explain situations where elemental purity is acceptable but particle growth occurs. Stabilizers or complexing agents may introduce new organic residues or metal ion risks and are therefore unsuitable for direct addition to ultrapure copper sulfate finished product solutions.

[0006] Hydrogen peroxide is not an unfamiliar oxidant in copper chemistry, but simply understanding it as "adding an oxidant to copper sulfate" does not solve the practical problems of electronic-grade products. If too little is added, residual cuprous oxide may still disproportionate during storage. If too much is added, residual hydrogen peroxide may affect downstream electroplating solution additives or pose release risks. More importantly, without first determining the cuprous ion concentration, the amount of hydrogen peroxide added can only be determined empirically, making it difficult to maintain consistency across different batches, storage periods, and particle sizes.

[0007] Therefore, a treatment method for the storage stability of ultrapure copper sulfate solution is needed, which can shift the source of particle abnormalities from "foreign particles" back to "the valence risk of residual monovalent copper", and eliminate the hidden danger of nano-copper precipitation during storage before filling, without introducing new metal impurities, significantly changing the main components, or relying on long-term storage trial and error. Summary of the Invention

[0008] The technical problem to be solved by this invention is: for ultrapure copper sulfate solutions with qualified elemental purity at the factory but whose nanoparticle count tends to increase during storage, how to identify and eliminate the potential source of residual cuprous ions before filling, so that the solution no longer continuously generates nano-sized copper particles during storage, while avoiding the introduction of new metallic impurities or organic stabilizers that may bring the risk of organic residues into electronic-grade products.

[0009] To address the aforementioned technical problems, this invention provides a method for suppressing the precipitation of nano-copper in ultrapure copper sulfate solution during storage. The method involves obtaining a sample solution from the online flow path after the ultrapure copper sulfate solution has undergone electrolytic preparation and terminal filtration, but before filling, and determining the concentration of cuprous ions in the sample solution. Then, based on the cuprous ion concentration, the volume of the solution to be treated, and the stoichiometric relationship of hydrogen peroxide oxidizing monovalent copper to divalent copper, the theoretical amount of electronic-grade hydrogen peroxide to be added is calculated, and the calculated amount is obtained according to the cuprous equivalent oxidation coefficient. Subsequently, electronic-grade hydrogen peroxide is injected in stages into the flowing ultrapure copper sulfate solution through a clean material pipeline, allowing it to react with cuprous ions under controlled temperature and residence time. Finally, the residual cuprous ions and residual hydrogen peroxide are checked; if they are within acceptable limits, the solution is filled; if not, additional hydrogen peroxide is added or the residence time is extended.

[0010] In a preferred approach, cuprous ion detection is performed using a split sample solution branch, ensuring that the complexing chromogenic reagent used for detection does not flow back into the main product line. This method obtains the concentration of monovalent copper without introducing the detection reagent into the ultrapure copper sulfate product. The detection results can be corrected using a blank matrix of the same acidity, minimizing the influence of the copper sulfate matrix's color, acidity, and copper content on the determination of low-concentration cuprous ions.

[0011] In a preferred approach, the amount of electronic-grade hydrogen peroxide added is determined using a cuprous equivalent oxidation factor of 1.05 to 1.20. This range is not intended to maximize the amount of oxidant, but rather to provide a small margin to compensate for sampling, mixing, trace side reactions, and detection errors. If consecutive batch verifications show high levels of residual hydrogen peroxide, this factor can be lowered. If the residual cuprous ion concentration is close to the cuprous limit, this factor can be maintained or slightly increased.

[0012] In a preferred approach, hydrogen peroxide is added in stages through at least two injection points, and the reaction is completed after injection via a static mixing section and a residence reaction pipeline. The significance of staged addition is to reduce the local instantaneous concentration of oxidant, avoid the potential impact of excessive local hydrogen peroxide on the compatibility of downstream additives, and also facilitate the formation of more uniform reaction conditions in the pipeline.

[0013] In a preferred approach, when residual hydrogen peroxide does not meet the oxidant limit but residual cuprous ions are within acceptable limits, new chemical reagents are not added blindly. Instead, residual oxidant is reduced through methods such as ultraviolet irradiation, temperature maintenance, or inert gas deoxygenation. Specifically, ultraviolet irradiation uses a low-pressure mercury lamp with a wavelength of 185 nm or 254 nm, with an irradiation dose of 100 mJ / cm² to 500 mJ / cm²; temperature maintenance is maintained at 40°C to 60°C for 10 to 60 minutes; and inert gas deoxygenation uses nitrogen or argon gas filtered through a 0.003 μm filter, purging with a gas-liquid volume ratio of 0.5:1 to 2:1. The common goal of these treatments is to minimize the introduction of new dissolved impurities, meeting the cleanliness requirements for wet electronic chemicals.

[0014] This invention also provides a processing system for implementing the above-described method. The system includes a clean sampling unit, a cuprous detection unit, an equivalent calculation unit, a hydrogen peroxide metering injection unit, a residence reaction pipeline, and a verification and filling switching unit. These units are not simply arranged side-by-side, but rather configured in a closed loop: "the measured cuprous equivalent determines the amount of micro-oxidant added, and the verification result determines filling or adjustment." Thus, the amount of hydrogen peroxide used is no longer an empirical value, but is driven by the actual measurement of residual monovalent copper.

[0015] Compared with existing technologies, this invention has at least the following advantages. First, the problem identification is closer to the chemical root cause of abnormal particle storage. For cases where the particle composition remains copper and the total copper content is essentially unchanged, this invention targets cuprous ions for control, rather than simply increasing filtration intensity. Second, the treatment method is lightweight. Electronic-grade hydrogen peroxide is mainly converted into water and oxygen after the reaction, without introducing new metal ions or requiring the addition of organic stabilizers to the finished product. Third, the dosage can be controlled in a batch-based closed-loop manner. The dosage is calculated using cuprous concentration, the volume to be treated, and the equivalence factor, and verified using residual cuprous ions and residual hydrogen peroxide, avoiding the risks of both over- and under-dosing. Fourth, this method is performed before filling, allowing the removal of disproportionation sources before the finished product enters the storage state, making it suitable for integration into existing ultrapure copper sulfate production lines. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall process of the method described in this invention.

[0017] Figure 2 This is a schematic diagram of the online quantitative micro-oxidation treatment system described in this invention.

[0018] Figure 3 This is a schematic diagram illustrating the closed-loop calculation of the concentration of cuprous oxide and the amount of hydrogen peroxide added according to the present invention.

[0019] Figure 4 This is a schematic diagram of the segmented injection and residence reaction pipeline described in this invention.

[0020] Figure 5 This is a schematic diagram comparing the mechanism of nano-copper precipitation during storage with the inhibition path of this invention.

[0021] Figure 6 This is a schematic diagram illustrating the residual indicator review, supplementation, and extended stay decision-making process described in this invention.

[0022] Figure 7 This is a schematic diagram illustrating the risk review and grading of particles during storage as described in this invention. Detailed Implementation

[0023] The present invention is described below with reference to specific examples and accompanying drawings. The following are illustrative examples and do not constitute a limitation on the scope of protection of the present invention. Unless otherwise stated, wetted parts should preferably be made of polytetrafluoroethylene, perfluoroalkoxy resin, polyvinylidene fluoride, or a clean material verified not to release metal ions. Sampling, injection, and filling processes should preferably be carried out in a clean environment matching the grade of the ultrapure copper sulfate product.

[0024] like Figure 1As shown, the method of the present invention may include steps 101 to 106. In step 101, after the ultrapure copper sulfate solution has completed electrolytic preparation, purification, and terminal filtration, it is not immediately filled. Instead, a sample solution is first obtained from the online flow path before filling. This sampling position is preferably set after the terminal filter and before the filling valve, so that the sample solution can represent the state of the product that is about to enter the packaging container. The sampling branch is preferably sampled after a single rinse, with the initial rinse solution discarded and the subsequent sample solution entering the cuprous detection unit. This can reduce the influence of the sampling valve cavity, dead corners, and initial residual liquid in the branch on the determination of low-concentration cuprous sulfate.

[0025] In step 102, the concentration of cuprous ions in the sample solution is determined. The cuprous ion concentration can be obtained by a monovalent copper selective complexation colorimetric method, an electrochemical microelectrode method, or other process-validated monovalent copper analytical methods. For the complexation colorimetric method, the sample solution can be contacted with a monovalent copper selective complexing agent in a deoxygenated dilution medium. Preferably, the monovalent copper selective complexing agent is 2,9-dimethyl-1,10-phenanthroline (neo-cucurbitane), and the colorimetric reaction is carried out in an acetate-sodium acetate buffer system with a pH of 4.0 to 6.0 for 10 to 30 minutes, and the detection wavelength is 450 nm to 460 nm. During the determination, a copper sulfate blank matrix with the same acidity and copper content is used for background correction, and quantification is performed using the standard addition method or the external standard method. Subsequently, the absorbance is read and corrected by a copper sulfate blank matrix with the same acidity. The detection branch is isolated from the main product pipeline, and the colorimetric reagent and waste liquid do not flow back into the product. For electrochemical methods, electrode contact materials need to be validated for metal deposition and particle release to prevent the detection process itself from becoming a source of contamination.

[0026] In actual production, the concentration of cuprous ions may be very low, and the ultrapure copper sulfate solution itself is quite dark in color. To avoid directly amplifying the detection error to the amount of hydrogen peroxide added, step 102 preferably involves at least two parallel measurements for each batch of sample solution. When the relative deviation between the two measurements exceeds the range specified by the process, resampling is performed, and the sampling branch is checked for residual air or previous batch solution. If the two measurements are consistent, the average value can be used as the input for equivalent calculation. Although this process adds a small amount of analysis time, for finished solutions with storage periods of several weeks, it can result in more stable control of the addition amount.

[0027] In step 103, the theoretical amount of electronic-grade hydrogen peroxide to be added is calculated based on the cuprous ion concentration and the volume of the solution to be treated. The measured cuprous ion concentration is converted to the molar amount of monovalent copper in the solution, and then the theoretical amount of hydrogen peroxide is calculated based on the effective oxidation equivalent of hydrogen peroxide oxidizing monovalent copper to divalent copper. Considering trace side reactions, pipeline mixing efficiency, and measurement errors, the theoretical amount is multiplied by a cuprous equivalent oxidation coefficient of 1.05 to 1.20 to obtain the calculated amount. The amount of hydrogen peroxide added corresponding to this coefficient is lower than the amount added using empirical dosing methods, used only to eliminate residual cuprous ions without turning the finished solution into a system containing significant residual oxidant. The chemical reaction equation for the oxidation of monovalent copper by hydrogen peroxide is: 2Cu → 2Cu + + H2O2 + 2H + → 2Cu 2+ According to the equation + 2H₂O, 1 mole of hydrogen peroxide can oxidize 2 moles of monovalent copper to divalent copper. The theoretical amount to be added is calculated by converting this molar ratio and then multiplying it by the copper(II) equivalent oxidation coefficient.

[0028] like Figure 3 As shown, the cuprous equivalent oxidation coefficient can be gently adjusted between production batches. If a batch review shows that the residual cuprous ion concentration is close to the cuprous limit, while the residual hydrogen peroxide concentration is below the oxidant limit, the next batch can maintain the original coefficient or slightly increase it. If two consecutive batches have residual cuprous ion concentrations far below the cuprous limit but residual hydrogen peroxide concentrations high, the coefficient for the next batch can be reduced by 0.02 to 0.05. This adjustment is not an online real-time oscillation control, but rather a batch-to-batch fine-tuning for stable production, avoiding fluctuations in dosage due to single detections.

[0029] In step 104, the calculated amount of electronic-grade hydrogen peroxide is added to the flowing ultrapure copper sulfate solution. The electronic-grade hydrogen peroxide can be diluted first with electronic-grade ultrapure water or an ultrapure copper sulfate solution of the same acidity before being introduced into the main flow path via a metering pump. Dilution provides greater stability to the metering pump's operating range and reduces the instantaneous hydrogen peroxide concentration near the injection point. The injection pipeline should preferably be made of perfluorinated materials, and the pump head and check valve must be verified against metal deposition.

[0030] like Figure 4 As shown, the calculated dosage can be allocated to multiple injection points. A more reliable allocation method is to add 50% to 80% of the calculated dosage at the first injection point, and after the first static mixing section, add the remaining amount at the second or third injection point. If the main flow rate is high or the cuprous ion concentration is high, the length of the residence reaction pipeline can be increased, rather than simply increasing the local injection concentration. The reaction temperature can be controlled between 15°C and 35°C, and the residence time can be controlled between 5 minutes and 30 minutes. At too low a temperature, the reaction rate decreases; at too high a temperature, the decomposition of residual hydrogen peroxide and the difficulty of controlling solution cleanliness increase.

[0031] In step 105, the solution after the reaction is checked for residual cuprous ions and residual hydrogen peroxide. The residual cuprous ion check is used to determine whether the disproportionation precursor has been substantially eliminated during storage. The residual hydrogen peroxide check is used to determine whether there is a risk of excessive oxidant entering the packaging container. Both are indispensable. If only residual cuprous ions are considered, products with high hydrogen peroxide levels may be released. If only residual hydrogen peroxide is considered, it cannot be determined whether cuprous ions will still form metallic copper nuclei during storage.

[0032] like Figure 6 As shown, when the residual cuprous ion concentration exceeds the cuprous limit, the treatment system does not directly fill the solution. Instead, a small dose of electronic-grade hydrogen peroxide is added according to the verification results, and the solution is passed through the residence reaction pipeline again. The amount added can be calculated based on the cuprous equivalent of the excess. The verification after addition still simultaneously detects residual cuprous ions and residual hydrogen peroxide. When the residual cuprous ion concentration is within acceptable limits but the residual hydrogen peroxide concentration exceeds the oxidant limit, the treatment system no longer adds hydrogen peroxide. Instead, it extends the residence time or initiates treatments such as deoxygenation maintenance, ultraviolet irradiation, or temperature maintenance to reduce the residual hydrogen peroxide concentration.

[0033] In step 106, the solution is switched to clean filling only when the residual cuprous ion concentration is not higher than the cuprous limit and the residual hydrogen peroxide concentration is not higher than the oxidant limit. The filling container can be a fluoropolymer-lined container or a high-density polyethylene clean container that has been verified for particle cleaning and metal precipitation. No stabilizers, complexing agents, or corrosion inhibitors containing metal ions are added before or after filling. For solutions treated by this invention, the cleanliness of the packaging container remains important, but its role is to prevent exogenous particles, not to replace chemical treatment of the cuprous source.

[0034] like Figure 5 As shown, untreated ultrapure copper sulfate solutions containing trace amounts of cuprous ions may slowly evolve along the pathway of "residual Cu+, disproportionation, metallic copper clusters, and nano-copper particles" during storage. The insidious nature of this pathway lies in the fact that the generated particles are still copper, making them difficult to identify as foreign contamination by elemental analysis. This invention, however, converts Cu+ back to Cu2+ before filling by measuring the Cu+ equivalent, quantitatively adding electronic-grade hydrogen peroxide, and verifying residual indicators, thus preventing the continued disproportionation and precipitation of precursors during storage.

[0035] In Example 1, the solution to be treated is an ultrapure copper sulfate solution used for replenishing copper electroplating. Its main components are copper sulfate and sulfuric acid, and the terminal filtration precision is at the nanometer or submicron level commonly used in wet electronic chemicals. A sampling branch is set up before the filling valve on the production line; the branch is rinsed before sampling. The cuprous ion detection unit uses deoxygenation dilution and selective complexation color development with monovalent copper; the colorimetric solution does not flow back to the main line. The detected cuprous ion concentration is converted to the molar amount of monovalent copper in the batch to be treated, and the processing system calculates the theoretical amount of electronic-grade hydrogen peroxide to be added based on this.

[0036] In this embodiment, the cuprous equivalent oxidation coefficient is initially set to 1.10. Electronic-grade hydrogen peroxide is first diluted with electronic-grade ultrapure water to a convenient concentration, and then injected in two stages using a perfluorinated metering pump. The first injection point is located at the front end of the static mixer, adding approximately 70% of the calculated amount. The second injection point is located in the middle of the residence reaction line, adding the remaining amount. The reaction temperature is maintained near room temperature, and the residence time is approximately 15 minutes. During verification, if the residual cuprous ion concentration is below the cuprous limit and the residual hydrogen peroxide concentration is below the oxidant limit, then the batch of solution proceeds to filling.

[0037] In Example 2, the concentration of cuprous ions in the solution to be treated fluctuated significantly. If a fixed amount of hydrogen peroxide is still used, batches with low cuprous ions may show higher residual hydrogen peroxide levels, while batches with high cuprous ions may show higher residual cuprous ion levels. This example uses an inter-batch coefficient correction. If two consecutive batches show higher residual hydrogen peroxide levels and residual cuprous ion levels are far below the limit, the cuprous equivalent oxidation coefficient for the next batch is reduced from 1.12 to 1.08. When the residual cuprous ion level in subsequent batches approaches the cuprous limit, it is restored to 1.10. This correction is relatively small, avoiding excessive adherence to single-batch detection errors.

[0038] In Example 3, the residual hydrogen peroxide in the post-reaction solution was slightly higher than the oxidant limit, but the residual cuprous ions met the requirements. The treatment system directs the solution into the UV irradiation section and through a clean maintenance pipeline at a low flow rate to reduce the residual hydrogen peroxide before retesting. Alternatively, slight temperature increase or inert gas deoxygenation can be used for maintenance. The choice of these three methods depends on the production line equipment conditions, but the common principle is to avoid introducing new metal ions or organic stabilizers.

[0039] In Example 4, representative samples of the treated product are retained and subjected to accelerated storage observation at 25°C to 40°C. This observation is not a release step that must be defined in the claims, but rather a verification method for production line maintenance. If the particle count growth rate of the retained sample is in the low-risk zone during the storage period, the existing cuprous equivalent oxidation coefficient can be maintained. If it enters the verification zone, the sampling branch, cuprous detection calibration, and container cleaning are reviewed. If it enters the treatment zone, the coefficient, residence time, or injection point allocation are adjusted. Figure 7 This illustrates the logical relationship of this risk classification.

[0040] The key to this invention lies not in listing all possible oxidants as options, but in using the actual measurement of residual cuprous ions as a control quantity for pre-filling treatment. If an oxidation system that introduces metal ions, strong complexes, or difficult-to-remove organic matter is used, even if Cu+ can be oxidized, it may not meet the impurity requirements for ultrapure copper sulfate products. The advantage of electronic-grade hydrogen peroxide is that the reaction residue is mainly water and oxygen, and its residual amount can be reduced through independent verification and post-processing.

[0041] This invention also incorporates the function of terminal filtration. Terminal filtration can still be installed before the micro-oxidation treatment to remove particles already formed during the preparation process. Alternatively, a clean protective filter can be installed after the micro-oxidation treatment to intercept occasional particles generated in the pipeline. However, filtration should not be considered a replacement for the core methods of this invention. For nano-copper that continues to form during storage, what truly needs to be addressed is the precursor, namely, residual cuprous ions.

[0042] In some implementations, the limits for cuprous oxide and oxidant can be determined based on the customer's particle size, packaging volume, and shelf life. For example, for products with shorter shelf lives and more lenient particle size requirements, wider verification limits can be selected. For products used in advanced packaging or fine-linewidth interconnects, more stringent limits for cuprous oxide and oxidant can be chosen. The specific values ​​of the limits do not act in isolation; they must be validated in conjunction with the lower limit of quantitation (LQ), sampling repeatability, and sample particle trend of the detection method.

[0043] The processing system of the present invention is as follows Figure 2 As shown. The clean sampling unit 210 obtains a sample solution from the online flow path before filling. The cuprous ion detection unit 220 measures the cuprous ion concentration in the sample solution. The equivalence calculation unit 230 calculates the amount to be added based on concentration, volume, and equivalence factor. The hydrogen peroxide metering injection unit 240 injects the hydrogen peroxide in stages according to the calculated amount. The residence reaction pipeline 250 provides mixing and reaction time. The verification and filling switching unit 260 determines whether to fill, replenish, or extend the residence time based on the verification results. Data and material flow between units are interconnected. Figure 1 Steps 101 to 106 correspond to the steps in the text.

[0044] It should be noted that this invention is compatible with existing ultrapure copper sulfate production lines. For production lines already equipped with terminal filtration and clean filling, only a split sampling, micro-injection, and residence verification module needs to be added before filling. For newly built production lines, the sampling, detection, calculation, injection, residence, and verification modules can be integrated into one unit. Regardless of the arrangement, the waste liquid in the detection branch should not flow back to the main product, and the hydrogen peroxide injection branch should also be equipped with an anti-backflow structure to prevent local concentration anomalies caused by pressure fluctuations in the main line.

[0045] This invention's interpretation of abnormal particle growth during storage can also aid in production troubleshooting. If particle growth persists after treatment, priority should be given to investigating container wall precipitation, filling environment, particle release from end valves, and sampling and counting errors, rather than blindly increasing oxidant. If there is a significant difference in the particle growth slope between untreated and treated samples, it indicates that the original anomaly was primarily related to residual cuprous ions. This invention, by incorporating cuprous ions into pre-release verification, transforms this type of troubleshooting from experience-based judgment into a recordable process variable.

[0046] In this invention, cuprous ion concentration refers to the amount of copper in the sample solution that exists in the form of monovalent copper and can be further oxidized to divalent copper by hydrogen peroxide. This concentration is not equivalent to the total copper concentration, nor is it equivalent to the concentration of foreign metal impurities. The total copper concentration is usually determined by the copper sulfate matrix and is much higher than the cuprous ion concentration. The concentration of foreign metal impurities reflects the content of non-matrix elements such as sodium, potassium, iron, nickel, and chromium. This invention separates the cuprous ion concentration because the precursor of the nano-copper particles during storage can originate from the valence state changes of the main copper element itself, rather than from contamination by foreign elements.

[0047] In this invention, the cuprous equivalent oxidation coefficient refers to a small margin coefficient set based on the theoretical amount of hydrogen peroxide added. The theoretical amount of hydrogen peroxide added is calculated by converting the measured cuprous ion concentration and the volume to be treated. The cuprous equivalent oxidation coefficient is used to cover sampling errors, minor side reactions, pipeline mixing efficiency, and metering pump pulsation. This coefficient should not be interpreted as an arbitrarily amplified safety factor. If the coefficient is too high, the residual hydrogen peroxide verification pressure increases. If the coefficient is too low, the residual cuprous ions may be unacceptable.

[0048] In this invention, the cuprous limit refers to the upper limit of residual cuprous ions allowed to enter the filling process after micro-oxidation treatment, and the oxidant limit refers to the upper limit of residual hydrogen peroxide allowed to enter the filling process. The cuprous limit is used to control the risk of continued formation of metallic copper nuclei during storage, while the oxidant limit is used to control the impact of hydrogen peroxide on downstream electroplating systems, packaging stability, and customer release criteria. The two limits correspond to different risks; therefore, one limit cannot be used to replace the other.

[0049] In this invention, residual cuprous ions refer to the amount of copper still present in the solution as monovalent copper after the reaction, and residual hydrogen peroxide refers to the amount of hydrogen peroxide still possessing oxidizing ability in the solution after the reaction. Both can be measured separately at the same sampling point or separately at adjacent sampling points. For the detection branch, the use of colorimetric reagents or quenching reagents incompatible with the main product is permitted, but these reagents must not be refluxed back to the main product line.

[0050] In this invention, the calculated addition amount refers to the amount of electronic-grade hydrogen peroxide added, output by the equivalence calculation unit to the metering injection unit. The calculated addition amount can be expressed as mass, volume, or metering pump pulse count, but should be convertible back to the effective hydrogen peroxide content within the system. For electronic-grade hydrogen peroxide stock solutions of different concentrations, as long as the conversion relationship remains consistent, the metering injection unit can execute the addition according to the calculated amount.

[0051] To ensure reliable test results, the sampling branch should ideally be equipped with venting and quantitative rinsing mechanisms. Cuprous ions are easily affected by air, tube wall condition, and trace amounts of redox substances. If the sampling branch is left to stand for an extended period, the sample solution within it may differ from the main flow path. In practice, the sampling branch can be rinsed with the solution to be tested before entering the detection cell. After cleaning the detection cell, the background value should be read using a blank matrix before measuring the sample solution. This reduces the cumulative effects of residual solution in the branch, ambient oxygen, and matrix color on the determination of low-concentration cuprous ions.

[0052] To ensure the above sampling conditions are met, the sampling branch can be quantitatively rinsed during sampling, and the background metal content of the rinsing effluent can be monitored. Specifically, the sampling branch is continuously rinsed with the ultrapure copper sulfate solution to be tested or a clean solution of the same specification, and the background metal impurities in the rinsing effluent are monitored online or offline. When the relative fluctuation of several adjacent monitoring values ​​falls within a set range, it is considered that the amount of metal impurities dissolved in the sampling branch has stabilized. The sample obtained at this time can represent the true copper content of the main channel, thus avoiding the inclusion of residual or slowly dissolved metals from the previous batch on the branch wall, which would amplify the measurement error. At the same time, sampling and testing operations should be carried out in a clean environment with particle filtration, such as setting the sampling point and the testing cell in a local laminar flow hood, a clean sampling box, or an environment of equivalent cleanliness. This prevents environmental suspended particles from superimposing into the sample solution or testing cell during sampling, color development, and reading, thereby ensuring that the low-concentration copper content measurement and subsequent particle-related verification are not contaminated by particles in the sampling environment.

[0053] For complexometric colorimetric assays, the colorimetric reaction should be carried out under repeatable acidity and ionic strength conditions. Due to the high divalent copper content in ultrapure copper sulfate solutions, direct colorimetric analysis is easily affected by background absorption. Errors can be reduced through quantitative dilution, matrix-matched blanks, and fixed reaction times. If electrochemical assays are used, it is advisable to confirm the electrode surface memory effect to avoid the influence of reducing components in previous sample solutions on subsequent results.

[0054] When the cuprous ion concentration is below the lower limit of quantitation (LQ) of the detection method, the LQ can be used as a conservative input, or a lower fixed micro-oxidation amount can be adopted based on process validation results. The former is suitable for products with long storage periods and strict particle size control, while the latter is suitable for products with short storage periods or products with consistently low cuprous ion concentrations verified through multiple batches. Regardless of the method used, residual hydrogen peroxide verification should still be retained, as low cuprous batches are most prone to relative excess oxidant.

[0055] The quality of hydrogen peroxide stock solution also needs to be controlled. Electronic-grade hydrogen peroxide should be used only after verification of metal impurities, non-volatile residues, and particulate matter indicators. Storage tanks and pipelines should not be made of materials that easily release metal ions. If the hydrogen peroxide stock solution has been stored for a long period, its effective content must be verified before calculating the amount to be added. Otherwise, measuring according to the nominal concentration may lead to deviations in the actual amount added, resulting in unacceptable residual cuprous ions or excessive residual hydrogen peroxide.

[0056] The arrangement of segmented injection can be adjusted according to the production line flow rate. Low-flow production lines can use two injection points and one static mixer. High-flow production lines can use three injection points and two static mixers. The distance between injection points should not be mechanically set solely based on pipe length; mainstream velocity, mixer pressure drop, temperature, and detection response time should also be considered. If the mainstream velocity is high, simply extending the reaction time can be achieved by increasing the residence time in the pipe volume, without necessarily increasing the local hydrogen peroxide concentration.

[0057] The residence reaction pipeline can utilize coils, straight pipe combinations, or micromixing modules with clean liners. Its design prioritizes allowing sufficient time for hydrogen peroxide to contact cuprous ions while avoiding dead zones. Prolonged residence in dead zones can lead to localized particle precipitation or hydrogen peroxide decomposition producing gas, posing a risk of bubbles and particles to subsequent filling. Therefore, the pipeline should facilitate evacuation, flushing, and periodic validation.

[0058] In a batch production approach, the processing system can operate in a cycle of "pre-batch blank, in-batch verification, and post-batch rinse." The pre-batch blank confirms the absence of residue in the detection and metering branches. The in-batch verification confirms that the micro-oxidation reaction is proceeding as expected. The post-batch rinse prevents copper sulfate solution from crystallizing or becoming locally concentrated in the branches. This cycle does not alter the core steps of the standalone method but reduces misjudgments caused by insufficient branch maintenance in actual production lines.

[0059] In another continuous production method, ultrapure copper sulfate solution passes through an online processing system at a stable flow rate. A cuprous ion detection unit samples at set intervals, and the calculated addition amount is updated based on the most recent or multiple detection results. If the detection cycle is long, the previously calculated addition amount can be maintained between two detections. If the system detects a sudden change in cuprous ion concentration, the product from that period is transferred to an intermediate tank for verification instead of being directly filled. This isolates abnormal batches before packaging.

[0060] Comparative Example 1 illustrates a treatment method that only adds terminal filtration without performing copper equivalent micro-oxidation. Because this method can only retain already formed particles and cannot handle Cu+ still dissolved in the finished product solution, the filtered product may continue to generate new copper nuclei during storage, resulting in a rebound in the particle count. This comparative example demonstrates that if the particle source is Cu+ that has not yet formed nucleations in the solution, filtration cannot fundamentally eliminate delayed particles.

[0061] Comparative Example 2 describes a treatment method where hydrogen peroxide is added directly based on a fixed empirical amount without measuring the cuprous ion concentration. Because this method does not use actual cuprous ion measurement as the basis for the addition amount, batches with low cuprous ion concentrations may have excessive residual hydrogen peroxide, while batches with high cuprous ion concentrations may have insufficient oxidation, resulting in an uncontrolled trend in opposite directions between batches. Compared to this invention, this method lacks the step of "actual cuprous ion measurement driving the addition amount," and cannot reliably balance cuprous ion elimination and oxidant residue.

[0062] Comparative Example 3 describes a treatment method that uses organic additives with complexing or stabilizing effects to inhibit copper nucleation. However, the addition of organic matter introduces risks related to total organic carbon and compatibility with downstream electroplating additives. Even if this method delays nucleation, it may still result in wet electronic chemicals failing to meet customer release requirements, thus transforming particulate issues into new organic residue problems. This invention does not rely on such stabilizers but instead converts Cu+ to Cu2+, reducing copper nuclei at the reaction precursor level.

[0063] Comparative Example 4 involved reserving ample air head space in the packaging container to attempt to slowly oxidize residual Cu+ using oxygen from the air. Because this method relies on gas-liquid mass transfer, the oxygen transfer conditions near the liquid surface and at the bottom of the container differ significantly, leading to inconsistent oxidation rates of cuprous ions throughout the solution. Furthermore, the air head space may introduce particles or carbon dioxide, making it unsuitable as a pre-release treatment for electronic-grade products. This invention performs micro-oxidation in the flow path before filling, allowing for more controllable reaction conditions.

[0064] The above comparative examples do not imply that filtration, container cleaning, or packaging atmosphere control are without value. They remain necessary cleanliness measures in the production of ultrapure copper sulfate, but their boundaries of application differ. Filtration and cleaning address exogenous particles and existing particles, while packaging atmosphere control addresses fluctuations in the storage environment. This invention addresses the chemical source of residual Cu+ within the finished solution continuing to generate nano-copper during storage. These measures can be used synergistically, but they cannot replace each other.

[0065] It should be noted that the core of this invention does not lie in the chemical reaction of hydroxide ions with peroxide itself, but in using the measured value of the residual cuprous ion concentration as the control quantity for quantitative micro-oxidation before filling, and constructing this control process as a closed loop of "measurement—equivalent calculation—segmented injection—dual index verification—filling / adjustment". This closed loop transforms the problem of nano-copper precipitation, which originally only appeared after the storage period, into a process controllable link that can be handled and released before filling.

[0066] In production line management, the system can save the cuprous ion concentration, calculated dosage, actual metering pump pulse count, reaction temperature, residence time, residual cuprous ions, residual hydrogen peroxide, and particle sample retention results for each batch. Not all of these records need to be included in the claims, but they help demonstrate that the invention is not a one-time dosing experience, but rather a wet electronic chemical handling method that can be verified and traced during production.

[0067] For ultrapure copper sulfate solutions with different copper contents or acidities, the cuprous detection method and hydrogen peroxide addition conversion can be recalibrated. During calibration, a copper sulfate solution with the same or similar matrix as the product should be used as a blank to verify that the copper content, acidity, and particle count of the main component do not show adverse changes after the addition of hydrogen peroxide. If the acidity is significantly different, the stability of cuprous copper and the reaction rate of hydrogen peroxide may also differ, and the residence time and verification frequency should be adjusted accordingly.

[0068] For post-packaging sample observation, the daily particle count should not be the sole criterion for judgment. Instead, the rate of increase in particle count before and after storage should be given more attention. A single particle count is easily affected by sampling, shaking, instrument conditions, and localized particles within the container. The rate of increase is a better indicator of whether new particle sources remain during storage. Figure 7 The grading diagram in the figure is used to illustrate this trend review approach. T1 to T3 in the figure are process boundary markers, not fixed values.

[0069] If the customer requires extremely low residual hydrogen peroxide, this invention can divide the oxidation reaction and residual hydrogen peroxide reduction into two stages. The first stage completes Cu+ oxidation at the cuprous equivalent, and the second stage reduces hydrogen peroxide without introducing new impurities. A checkpoint is set between the two stages to avoid premature removal of hydrogen peroxide before the cuprous content is qualified, and also to avoid adding hydrogen peroxide after the cuprous content has been qualified.

[0070] Calibration of the metering pump is particularly important in equipment maintenance. Since this invention processes trace amounts of cuprous ions, the amount of hydrogen peroxide added is typically small. Metering pump pulse error, check valve hysteresis, and pipeline elasticity can all affect the actual amount added. The metering pump output can be calibrated periodically using either a gravimetric or volumetric method, and the calibration results should be written into the equivalent calculation unit. If the metering deviation exceeds the specified range, automatic filling should be suspended, and the process transferred to manual verification or intermediate tank handling.

[0071] This invention can also be configured with abnormal alarm logic. For example, if the copper content suddenly exceeds the historical batch average by a significant margin, the system can prompt an investigation into the electrolysis preparation section, anode status, dissolved oxygen, and reducing contamination. If residual hydrogen peroxide remains persistently high, the system can prompt an investigation into the hydrogen peroxide stock solution concentration, metering pump calibration, and residence tubing temperature. If both checks are satisfactory but the stored particle count continues to rise, the system will prompt an investigation into the packaging containers and filling environment. The above alarm logic serves implementation purposes but does not alter the fundamental scope of protection of this invention.

[0072] In a more production-line-oriented implementation, the processing system can include an intermediate buffer tank. This buffer tank is not for long-term storage, but rather for temporarily storing products not yet released during testing, replenishment, or extended storage periods. The buffer tank should have a clean lining and a bottom drain structure to prevent localized concentration of copper sulfate solution at the bottom or level gauge. Products entering the buffer tank should retain batch identification, and only those that pass verification should be filled; products that fail verification should be returned to the micro-oxidation treatment section.

[0073] When a production line needs to process ultrapure copper sulfate solutions of multiple concentrations, independent matrix blanks and calculation parameters can be established for different concentrations. Copper content, sulfuric acid content, and temperature all affect the detection background and reaction rate. Directly using the calibration curve of a low-concentration product for a high-concentration product may lead to improper background absorption correction, causing the measurement results to deviate from the true value. Conversely, directly using the residence time of a high-concentration product for a low-concentration product may result in a relative excess of hydrogen peroxide. Therefore, when switching between concentrations, it is advisable to first perform a small-flow validation with a representative sample solution.

[0074] When the cuprous detection unit uses a colorimetric method, the color development time can be fixed to a single value, for example, starting the timer after adding the reagent and reading the absorbance at the specified time. The color development time should not be varied according to operator habits, because the reading variation for low-concentration cuprous measurements is inherently small, and differences in reaction time will become significant errors. Automated systems can use the sampling valve's actuation signal to trigger the timing and write the absorbance reading time into the batch record.

[0075] When the cuprous oxide detection unit uses the electrochemical method, electrode cleaning and regeneration are equally important. If copper or organic matter adsorbs on the electrode surface, it can cause tailing in low-concentration measurements. Acid washing, water washing, and blank verification can be scheduled between measurements. If the blank verification fails, the system should not continue to use the measured value for equivalent calculations, but should instead prompt for electrode maintenance or switching to a backup detection channel.

[0076] For hydrogen peroxide injection points, check valves and purging structures are recommended. Check valves prevent backflow of copper sulfate solution from the main line into the hydrogen peroxide branch, while purging structures are used to drain residual liquid from the branch after each batch. If backflow occurs, localized reactions or crystallization may form within the hydrogen peroxide branch, potentially carrying abnormally concentrated liquid into the main line during the next batch startup. This risk is more pronounced in micro-injection systems because the branch volume is not negligible relative to the amount added in a single batch.

[0077] This invention can also be used for reworking already filled products, but reworking is not the preferred method. Reworking requires reopening the packaging container, increasing the risk of particulate and environmental contamination. Furthermore, copper particles that have formed during storage need to be removed by filtration or other means. This invention is more suitable for pre-filling processing, allowing micro-oxidation to occur in a clean, closed pipeline, and for verification before the product enters the container.

[0078] When determining the effectiveness of this invention, it is inappropriate to compare only the instantaneous particle count before filling. The instantaneous particle count before filling mainly reflects the cleanliness of filtration and filling, while the effect of this invention is more reflected in the particle growth trend during storage. A more reasonable evaluation method is to separately collect untreated samples, filtered samples, and samples treated by this invention, and observe the changes in particle count before and after storage under the same container, temperature, and sampling method. If the growth slope of the sample treated by this invention is significantly lower than that of the untreated sample and the filtered sample, it indicates that the source term control is effective.

[0079] For cases where the customer has specified particle counting channels, the same channel and sampling volume should be used for sample retention evaluation. Cross-sectional comparisons between channels with different particle sizes are not recommended. Nano-copper particles may initially appear primarily in smaller particle size channels during the early stages of storage, subsequently showing an increase in larger particle size channels. Focusing only on a single larger particle size channel may underestimate the early disproportionation nucleation risk. Focusing only on the smallest channel may be significantly affected by instrument noise. Therefore, process validation can record multiple channels simultaneously, but release criteria should be implemented according to customer specifications.

[0080] The inert gas back pressure in this invention primarily serves to stabilize the pipeline and control external air bubbles. The inert gas can be purified nitrogen or argon, and it should ideally undergo particle filtration and moisture control before entering the system. The back pressure does not need to be very high; it only needs to prevent the metering pump from pulsating and drawing in air while maintaining a stable main flow path. Excessive back pressure will increase the burden on the seals and may actually introduce a risk of particle release.

[0081] If an online particle counter is already installed in the production line, it can be placed in the bypass after verification for auxiliary confirmation. Online particle counting results do not replace verification of residual cuprous ions and residual hydrogen peroxide, because particle counting only reflects whether particles were present at that time and cannot determine whether Cu+ source terms still exist during storage. Combining particle counting with residual valence state verification can more clearly distinguish between "formed particles" and "chemical precursors that have not yet formed nucleations."

[0082] In some implementations, the equivalence calculation unit can be set to a manual verification mode. For production lines that are implementing this invention for the first time, the operator can verify the calculated dosage provided by the system. Verification includes checking the reliability of the cuprous oxide detection value, whether the hydrogen peroxide stock solution concentration has been updated, whether the volume to be processed is correct, and whether the previous batch verification results require a correction factor. Once the continuous batches have stabilized, the system can be switched to automatic calculation and automatic injection.

[0083] To avoid ambiguity caused by mass-produced documentation, each process step in this invention has a clear relationship with its preceding and following steps: sampling is used to obtain the cuprous concentration, the cuprous concentration is used to calculate the amount of hydrogen peroxide added, segmented injection is used to complete micro-oxidation in clean pipelines, and residual verification is used to determine filling or adjustment. If any core step is removed, the solution will lose its closed-loop mechanism. In particular, if the residual hydrogen peroxide verification is removed, the risk of excessive oxidant cannot be detected. If the residual cuprous verification is removed, the risk of disproportionation during storage cannot be confirmed.

[0084] If implementers only focus on the final particle count at storage without recording residual cuprous ions before filling, it becomes difficult to determine whether an anomaly occurred during preparation, micro-oxidation, packaging, or testing. This invention continuously records cuprous concentration, calculated addition amount, and residual verification results, ensuring a traceable valence state handling history for each batch of product. This history can be used for subsequent process audits and for locating problems during customer quality feedback.

[0085] If the implementer is concerned about the impact of hydrogen peroxide on downstream electroplating additives, a pre-use verification can be performed before the product enters the customer's electroplating tank. Since this invention already controls residual hydrogen peroxide below the oxidant limit before filling, the pre-use verification is usually only for customer confirmation. If the customer verification finds any abnormalities, the batch records of this invention can be used to determine whether the abnormality stems from packaging storage, transportation temperature, or environmental exposure after the customer opens the package.

[0086] This invention is also suitable for integration with supplier change management. When there is a supplier change for electronic-grade hydrogen peroxide, clean containers, perfluorinated tubing, or testing reagents, steps 101 to 106 can be repeated with a small batch of products, and the growth slopes of residual cuprous ions, residual hydrogen peroxide, and retained sample particles can be compared. If all three indicators remain within the existing process window, the scale-up can then be increased to the normal batch size. This can prevent a single raw material change from subtly altering the micro-oxidation effect.

[0087] In extreme cases, if the cuprous ion concentration is significantly higher than historical levels, this invention does not recommend simply increasing the amount of hydrogen peroxide added and releasing the batch directly. A better approach is to first transfer the batch of solution to an intermediate tank to investigate the sources of electrolytic preparation, raw copper, and reducing contamination, and then process it using a staged injection and multiple verification methods. This avoids localized overdose of hydrogen peroxide and also allows for the differentiated management of abnormal batches from normal batches.

[0088] For products with long transportation cycles, this invention can also incorporate transportation temperature into the sample retention verification criteria. If the product is typically transported at higher ambient temperatures, sample retention observation under corresponding temperature conditions can be added during the process validation stage. Increased temperature simultaneously affects the cuprous ion disproportionation rate, hydrogen peroxide decomposition rate, and particle Brownian aggregation behavior. Therefore, combining transportation temperature records with batch micro-oxidation records makes it easier to determine whether particle anomalies reported by customers are caused by changes in storage conditions.

[0089] For small-packaged products, the ratio of container surface area to solution volume is relatively high, making the effects of release or adsorption from the container's inner wall more pronounced. For large-packaged products, mixing uniformity and sample representativeness are more important. The equivalent micro-oxidation step of this invention can be completed in the main filling pipeline and then distributed to different packaging sizes. In this way, regardless of whether it is small or large packaging, the residual cuprous ions and residual hydrogen peroxide before entering the container have been verified, and differences in packaging sizes will not change the main control logic of micro-oxidation.

[0090] In a shutdown and restart scenario, the processing system should first be flushed with the sampling branch, injection branch, and residence tubing using a solution of the same batch or specification before resuming normal testing and filling. During shutdown, residual liquid in the tubing may experience temperature changes or local concentration. If directly added to normal product, this can affect the cuprous oxide detection value and particle background. By flushing and blank verification before startup, such non-steady-state effects can be excluded from the formal batch record, facilitating subsequent review and ensuring more complete and reliable records.

[0091] The specific concentrations, times, temperatures, limits, and piping materials in the above embodiments can be adjusted according to product specifications, production line scale, and customer particle requirements. Any equivalent substitutions made by those skilled in the art, without departing from the core concept of this invention—"measuring copper dioxide, quantitatively micro-oxidizing according to copper dioxide equivalents, and filling after dual-index verification"—regarding the detection method, number of injection points, length of the dwell pipe, or method for reducing residual hydrogen peroxide, should fall within the protection scope of this invention.

Claims

1. A method for inhibiting the precipitation of nano-copper during the storage of ultrapure copper sulfate solution, characterized in that, include: After the electrolytic preparation and terminal filtration of the ultrapure copper sulfate solution are completed and before filling, a sample solution is obtained from the online flow path. The concentration of cuprous ions in the sample solution is determined under the sampling conditions that the amount of metal impurities dissolved is stable and the sampling environment is filtered by particles. The concentration of cuprous ions is the amount of copper that can be oxidized by hydrogen peroxide, expressed as monovalent copper. Based on the concentration of cuprous ions, the volume of the solution to be treated, and the stoichiometric relationship of hydrogen peroxide oxidizing monovalent copper to divalent copper, the theoretical amount of electronic-grade hydrogen peroxide to be added is calculated. The calculated amount is obtained by multiplying the theoretical amount by the cuprous equivalent oxidation coefficient of 1.05 to 1.

20. Electronic-grade hydrogen peroxide is an aqueous solution of hydrogen peroxide controlled by metal impurities and particles. The calculated amount of electronic-grade hydrogen peroxide was injected in stages into the flowing ultrapure copper sulfate solution under inert gas back pressure, allowing it to react with cuprous ions at a temperature of 15°C to 35°C for a residence time of 5 to 30 minutes, thereby oxidizing the cuprous ions to divalent copper ions. The solution after the reaction is checked for residual cuprous ions and residual hydrogen peroxide. If the residual cuprous ions are not higher than the preset cuprous limit and the residual hydrogen peroxide is not higher than the preset oxidant limit, the solution is filled. If the above two limits are not met at the same time, electronic grade hydrogen peroxide is added or the deoxygenation residence time is extended according to the check results.

2. The method according to claim 1, characterized in that, The concentration of cuprous ions was obtained by split sampling, acidity-matched dilution, and selective complexation colorimetric determination of monovalent copper. The reagents used in the colorimetric determination only came into contact with the sample solution branch and did not enter the main product pipeline. The determination results were corrected by blank copper sulfate matrix from the same batch.

3. The method according to claim 1, characterized in that, The cuprous equivalent oxidation coefficient is corrected in continuous production batches based on the verification results. When the residual cuprous ion content is lower than the cuprous limit for two consecutive batches and the residual hydrogen peroxide content is higher than the oxidant limit, the cuprous equivalent oxidation coefficient of the next batch will be reduced by 0.02 to 0.

05.

4. The method according to claim 1, characterized in that, Before injection, electronic-grade hydrogen peroxide is diluted with ultrapure copper sulfate solution of the same acidity or electronic-grade ultrapure water. The diluted hydrogen peroxide solution enters at least two injection points through tubing made of polytetrafluoroethylene or perfluoroalkoxy resin.

5. The method according to claim 1, characterized in that, Segmented injection involves adding 50% to 80% of the calculated amount at the front end of the static mixing section and adding the remaining amount in the middle section of the residence reaction pipeline, so that the hydrogen peroxide concentration at any point in the reaction pipeline does not exceed 5 times the oxidant limit.

6. The method according to claim 1, characterized in that, The preset limit for copper is 0.005 mg / L to 0.050 mg / L, and the preset limit for oxidant is 0.05 mg / L to 0.50 mg / L, with both limits selected according to filling specifications, storage period, and particle count specifications.

7. The method according to claim 1, characterized in that, When the residual hydrogen peroxide is higher than the oxidant limit and the residual cuprous ion is not higher than the cuprous limit, the solution after the reaction is treated by at least one of the following: ultraviolet irradiation section, temperature holding section, or inert gas deoxygenation section, in order to reduce the residual hydrogen peroxide before filling.

8. The method according to claim 1, characterized in that, The filling process uses fluoropolymer-lined containers or high-density polyethylene clean containers that have been cleaned of particles. No stabilizers, complexing agents or corrosion inhibitors containing metal ions are introduced before or after filling.

9. A treatment system for suppressing the precipitation of nano-copper during the storage of ultrapure copper sulfate solution, characterized in that, It includes a clean sampling unit, a cuprous detection unit, an equivalent calculation unit, a hydrogen peroxide metering and injection unit, a residence reaction pipeline, and a verification and filling switching unit; The clean sampling unit is used to obtain sample solution from the online flow path before filling; the cuprous detection unit is used to determine the concentration of cuprous ions in the sample solution; the equivalent calculation unit is used to obtain the calculated amount of electronic-grade hydrogen peroxide to be added according to the method of claim 1; the hydrogen peroxide metering injection unit and the residence reaction pipeline are used to complete segmented quantitative micro-oxidation; and the verification and filling switching unit is used to switch filling, replenishment or extend the deoxygenation residence time based on the verification results of residual cuprous ions and residual hydrogen peroxide.

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