Double-channel ultrapure water equipment for silicon wafer production

Abstract

The invention relates to the technical field of preparation of ultrapure water for semiconductors, in particular to double-channel ultrapure water equipment for silicon wafer production, and aims to meet the dual water supply requirements of a first water supply loop with a high water quality grade and a second water supply loop with a low water quality grade in silicon wafer production. When water quality disturbance occurs in the low-water-quality second water supply loop, disturbance data are obtained through the online monitoring assembly, and the controller adjusts pulse waveform parameters of the second loop electric drive desalination module in a linkage mode to eliminate disturbance and recover water quality; meanwhile, peak shifting scheduling is carried out on the water production stage and the salt release stage of the second loop in combination with the water use state of the high-water-quality first water supply loop, and the situation that the water quality stability of the first loop is affected by water quality fluctuation of the second loop or ion concentration change in the salt release process is avoided; and the first loop is ensured to always meet the high-cleanliness water use requirement of the key process of the silicon wafer.

Description

Technical Field

[0001] This invention relates to the field of ultrapure water preparation technology for semiconductors, and more particularly to a dual-channel ultrapure water equipment for silicon wafer production. Background Technology

[0002] As the core substrate for semiconductor devices and photovoltaic modules, silicon wafers require extremely high purity ultrapure water during their production process (such as slicing, grinding, etching, cleaning, and final rinsing). Trace ions, organic matter, silicon residue, particles, and other contaminants in the water can directly lead to defects on the silicon wafer surface (such as white spots and scratches), device leakage, and reduced photoresist adhesion, ultimately affecting product yield and performance.

[0003] According to the standards of the Semiconductor Equipment and Materials International (SEMI) and industry practices, water used in silicon wafer production must meet two core water quality standards based on process requirements: Grade I water quality (critical cleaning / final rinsing water): resistivity ≥18.2MΩ・cm, total organic carbon (TOC) ≤3ppb, silicon content ≤0.01ppt, particle number (≥0.2μm) ≤1 particle / mL; Secondary water quality (general flushing / equipment makeup water): resistivity ≥10MΩ・cm, TOC ≤50ppb, silicon content ≤0.1ppt. Appropriate relaxation of the indicators is allowed, but the requirements of large flow rate, low cost and no cross-contamination must be met.

[0004] The current conventional process for preparing ultrapure water for silicon wafer production is as follows: raw water pretreatment (filtration, softening, activated carbon adsorption) → two-stage reverse osmosis (RO) → desalination unit (ion exchange mixed bed / EDI) → advanced treatment (ultraviolet oxidation, ultrafiltration, terminal filtration) → water distribution and reflux. To meet the requirements of differentiated water supply, the existing technology mainly adopts a solution of setting up two independent water supply loops: A high-quality loop: Deeply polishes the central permeate water (e.g., using a fine mixed bed, vacuum degassing, ultrafiltration, terminal filtration, etc.) and supplies it to key process points; One or more ordinary loops: centrally produced water is either simply treated or supplied directly to non-critical water points.

[0005] In existing semiconductor ultrapure water quality distribution systems, a critical and unresolved technical dilemma has long existed: water quality disturbances and maintenance requirements during the operation of ordinary water quality loops systematically threaten the safety and stability of the high-purity water supply loop. Specifically, the simplified or low-cost purification units used in ordinary loops are prone to disturbances in the quality of the effluent (such as resistivity, TOC, and especially silicon content) when dealing with fluctuations in raw water or performance degradation. This not only affects its own water supply but also transmits risks through two pathways: first, the potential risk of water quality penetration is difficult to completely eliminate under dynamic operating conditions due to physical isolation measures; second, the high-load impact generated during the regeneration of the purification unit in this loop, if overlapping with the peak production water demand of the high-purity loop, will directly compete for system resources, leading to unstable or interrupted critical production water supply.

[0006] In addition, existing systems often monitor characteristic pollutants such as silicon in a lagging and isolated manner, lacking real-time, closed-loop monitoring and adaptive control within the ordinary loop. Furthermore, the operation of the two loops is isolated from each other, and the maintenance work of the ordinary loop cannot be intelligently coordinated with the water usage patterns of the high-purity loop, resulting in inappropriate selection of maintenance windows. This can either interfere with production or force delays in maintenance, accumulating water quality risks. Summary of the Invention

[0007] Therefore, the present invention provides a dual-channel ultrapure water equipment for silicon wafer production to overcome the problems mentioned in the background art.

[0008] To achieve the above objectives, the present invention provides a dual-channel ultrapure water equipment for silicon wafer production, comprising at least a raw water pretreatment unit, a reverse osmosis unit, and a desalination unit, characterized in that it further comprises: A diversion unit is installed on the product water side of the desalination unit to divert the product water to the first water supply circuit and the second water supply circuit. The first water supply circuit is used for critical cleaning and to supply water to the final rinsing point. Along its water flow direction, it includes an ultraviolet treatment section, a polishing section, a degassing unit, an ultrafiltration unit, and a terminal filtration unit. The second water supply circuit is used for general rinsing and supplying water to the equipment's water replenishment points, and is equipped with an electric desalination module; An isolation and anti-cross-flow component is installed between the first water supply circuit and the second water supply circuit; An online monitoring component is installed in the second water supply circuit to acquire monitoring data of the second water supply circuit, the monitoring data including inlet water resistivity, outlet water resistivity, silicon content and total organic carbon; The controller is configured to determine whether water quality disturbance has occurred in the inlet water of the second water supply circuit based on the monitoring data of the second water supply circuit, adjust the pulse waveform parameters of the electric desalination module in response to the occurrence of water quality disturbance, and perform staggered scheduling of the water production stage and the salt release stage of the second water supply circuit after adjusting the pulse waveform parameters.

[0009] As a preferred technical solution for a dual-channel ultrapure water equipment for silicon wafer production, the electrically driven desalination module has a cross-flow structure, including a filling area filled with ion exchange resin of uniform particle size, an electrode plate assembly that cooperates with the filling area, and a high-frequency pulse power supply unit connected to the electrode plate assembly. The pulse waveform parameters output by the high-frequency pulse power supply unit include frequency and duty cycle.

[0010] As a preferred technical solution for dual-channel ultrapure water equipment used in silicon wafer production, the online monitoring components include inlet water monitoring components and outlet water monitoring components; The water inlet monitoring component is located at the water inlet of the electrically driven desalination module in the second water supply circuit, and includes a resistivity meter; The effluent monitoring component is located at the outlet of the electrically driven desalination module in the second water supply circuit, and includes a resistivity meter, a silicon content monitor, and an online total organic carbon analyzer.

[0011] As a preferred technical solution for dual-channel ultrapure water equipment used in silicon wafer production, the controller determines whether water quality disturbances have occurred based on monitoring data from the second water supply circuit, including: A water quality disturbance is determined to have occurred in response to the effluent silicon content exceeding a silicon content threshold. In response to the effluent silicon content not exceeding a silicon content threshold, the resistivity difference is calculated based on the influent resistivity and effluent resistivity. This difference, combined with the effluent total organic carbon concentration, determines whether a water quality disturbance monitoring condition has been triggered. Furthermore, based on the trigger duration of the water quality disturbance monitoring condition, it is determined whether a water quality disturbance has occurred in the second water supply circuit, including: Based on the determination result that the trigger duration is greater than or equal to the preset trigger duration, it is determined that a water quality disturbance has occurred in the second water supply circuit; Among them, the water quality disturbance monitoring conditions are that the resistivity difference is lower than the resistivity difference threshold and / or the total organic carbon concentration in the effluent is higher than the organic carbon concentration threshold.

[0012] As a preferred technical solution for a dual-channel ultrapure water system used in silicon wafer production, the controller responds to water quality disturbances by adjusting the pulse waveform parameters of the electrically driven desalination module according to the triggering cause of the disturbance. Specifically, this includes: The response is that the silica content in the effluent is higher than the silica content threshold, and the duty cycle and frequency of the pulse waveform are increased simultaneously. In response to the triggering cause being that the resistivity of the inlet water is lower than the resistivity difference threshold, the duty cycle of the pulse waveform is increased; In response to the triggering cause being that the total organic carbon concentration in the effluent is higher than the organic carbon concentration threshold, the frequency of the pulse waveform is increased.

[0013] As a preferred technical solution for a dual-channel ultrapure water system used in silicon wafer production, the controller calculates the current theoretical water production cycle and the expected regeneration time of the electrically driven desalination module based on the adjusted pulse waveform parameters, wherein: In response to the expected regeneration time point falling during the peak water usage period of the first water supply circuit, it is determined to implement off-peak scheduling.

[0014] As a preferred technical solution for a dual-channel ultrapure water equipment for silicon wafer production, the controller acquires historical water usage data of the first water supply circuit to determine several low-water-use periods and several high-water-use periods of the first water supply circuit.

[0015] As a preferred technical solution for a dual-channel ultrapure water equipment for silicon wafer production, the controller identifies the next low water usage period of the first water supply circuit and records it as the target period, and generates a scheduling instruction to adjust the start-up time of the salt release phase of the electrically driven desalination module of the second water supply circuit to the target period.

[0016] As a preferred technical solution for a dual-channel ultrapure water system used in silicon wafer production, the controller generates the scheduling instructions based on the following processes: Calculate the time difference between the expected regeneration time point and the start time of the target time period; The duty cycle or frequency of the pulse waveform is adjusted based on the time difference to reduce the saturation rate of the ion exchange resin. The time difference is negatively correlated with the duty cycle or the frequency.

[0017] As a preferred technical solution for dual-channel ultrapure water equipment for silicon wafer production, the isolation and anti-cross-flow component includes dual electric shut-off valves connected in series on the two water supply circuit connection pipelines and a relief valve and differential pressure sensor located between the two valves. The controller is also configured to determine whether the pressure difference between the two circuits exceeds a safety threshold range based on the data from the differential pressure sensor, and to close the dual electric shut-off valve and open the relief valve based on the determination result that the pressure difference exceeds the safety threshold range.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: the dual-channel ultrapure water equipment for silicon wafer production provided by the present invention achieves dual-loop water supply with different water qualities through a diversion design, which can adapt to the water needs of different processes. With the help of online monitoring components, the water quality disturbance of the second water supply loop is detected in real time. The controller adjusts the parameters of the electric drive desalination module in a targeted manner to quickly eliminate the disturbance. Furthermore, the water-sensitive period of the first water supply loop is avoided through peak scheduling. With the help of isolation and anti-cross-contamination components, the cross-contamination path is blocked. This ensures the high cleanliness and stability of the water used for critical cleaning and final rinsing, while also achieving an economical and efficient supply of general rinsing water. At the same time, the linkage adjustment prevents the disturbance of the low water quality loop from being transmitted to the high water quality loop, thus taking into account both the stringent process requirements of silicon wafer production and the safety and economy of equipment operation. In particular, the controller prioritizes silicon content, a core and sensitive indicator in silicon wafer production, to quickly respond to critical pollution risks and promptly cut off pollution output. It then uses a combination of resistivity difference and total organic carbon concentration monitoring and time-lapse verification to distinguish between real disturbances and accidental fluctuations, avoiding misjudgments or omissions. For different causes of disturbances, the controller specifically adjusts the pulse waveform parameters of the electric desalination module, enhancing ion adsorption capacity by adjusting the duty cycle and improving the migration efficiency of organic decomposition products by adjusting the frequency, achieving precise and efficient elimination of disturbances. Throughout the process, the controller's coordinated control ensures the rapid recovery and stability of water quality in the second water supply loop, while precise judgment and targeted adjustment reduce ineffective operations, avoiding interference with critical water use in the first water supply loop. This provides core assurance for the safety and stability of the dual-loop differentiated water supply, meeting the stringent process requirements of silicon wafer production. In particular, the controller accurately calculates the theoretical water production cycle and expected regeneration time of the electric desalination module based on the adjusted pulse waveform parameters. Combining the historical water usage data of the first water supply loop to divide the peak and off-peak periods, it determines whether the regeneration time conflicts with the critical water usage peak. Then, it identifies the next water usage off-peak period as the target period. By calculating the time difference and adjusting the pulse waveform parameters based on the negative correlation, it slows down the saturation rate of the ion exchange resin and accurately shifts the salt release stage to the off-peak period. From a time perspective, it avoids the interference of ion concentration fluctuations during the regeneration stage on the critical water usage of the first water supply loop. This ensures the regeneration effect of the electric desalination module, maintains the water quality stability of the first water supply loop, avoids ineffective adjustments, and improves the continuity and economy of the dual-loop water supply equipment, meeting the stringent process requirements of silicon wafer production. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the process flow of a dual-channel ultrapure water equipment for silicon wafer production according to an embodiment of the present invention; Figure 2 This is a flowchart illustrating the process of adjusting pulse waveform parameters by the controller in an embodiment of the present invention. Detailed Implementation

[0020] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0021] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0022] It should be noted that in the description of this invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0023] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0024] Please see Figures 1-2 As shown, these are respectively a process flow diagram of the dual-channel ultrapure water equipment for silicon wafer production according to an embodiment of the present invention and a flowchart of the controller adjusting pulse waveform parameters according to an embodiment of the present invention.

[0025] In this embodiment of the invention, a dual-channel ultrapure water equipment for silicon wafer production is provided. Both the first water supply circuit and the second water supply circuit are circuits separated from the fresh water circuit. The first water supply circuit is a high-quality water supply branch separated from the fresh water (water produced by the desalination unit). It undergoes multiple deep polishing processes and is used in the most critical production stages, with water quality requirements meeting ultrapure water standards. The second water supply circuit is a secondary high-quality water supply branch separated from the fresh water. Its treatment requirements are relatively low, and it is used in auxiliary and general production stages, with water quality requirements lower than those of the first water supply circuit.

[0026] In practice, the diversion ratio of the two water supply circuits is usually dynamically adjusted according to the actual water demand through the regulating valve in the diversion unit. This is existing technology and will not be elaborated further.

[0027] Specifically, the ultraviolet treatment section mainly destroys residual organic matter in the water and sterilizes it; the polishing section (usually referring to a mixed bed or EDI) increases the resistivity of the water to near the theoretical limit (18.2 MΩ·cm) and deeply removes ions; the degassing unit removes dissolved gases such as carbon dioxide from the water; the ultrafiltration unit removes particulate matter, bacteria, colloidal silica and microbial fragments; and the terminal filtration unit (usually a membrane filter of 0.1 microns or smaller) removes any possible pre-filter media shedding or particles, ensuring that the particulate matter index entering the pipeline is absolutely reliable.

[0028] Specifically, an electric desalination module (such as electro-deionization (EDI) or its improved version) is a highly efficient, continuous desalination technology that uses less chemical reagents. It can deeply desalinate, produce water with high resistivity, and partially remove weakly ionized substances (such as silicon and boron).

[0029] Specifically, in the cross-flow structure of the electric desalination module, the freshwater flow rate is typically 8 m / h to 12 m / h, and the concentrate flow rate is 30% to 50% of the freshwater flow rate. The electric desalination module specifically comprises: The filling zone is filled with ion exchange resin of uniform particle size; in practice, the particle size range of the uniform particle size ion exchange resin in the electrically driven desalination module is 0.5 mm to 1 mm, with a particle size deviation of ≤5%. The electrode plate assembly includes at least a pair of parallel electrode plates, which are respectively disposed on both sides of the filling area and in direct contact with the ion exchange resin in the filling area, for forming a direct current electric field perpendicular to the water flow direction within the filling area; it is understood that this structure can increase the number of charged ions (such as Na+) in the water. + Cl - SiO3 2- The migration path and residence time under the action of an electric field improve the efficiency of desalination and removal of charged pollutants, while reducing water flow short circuits and dead zones, and preventing local blockage of the resin bed. A high-frequency pulse power supply unit, the output of which is electrically connected to the electrode plate assembly, is used to apply a high-frequency pulse voltage to the electrode plate assembly; Among them, the high-frequency pulse power supply unit is configured to receive digital instructions from the controller and output an adjustable pulse waveform. The parameters of the pulse waveform include at least the frequency (adjustable range of 50Hz to 10kHz) and the duty cycle (adjustable range of 10% to 90%). It can be understood that the frequency (i.e. the speed of pulse periodic repetition) affects the migration-desorption kinetics of ions on the surface of resin particles and in the solution, and the duty cycle (i.e. the proportion of high-level energization time in the entire cycle) directly affects the applied effective electric field energy.

[0030] Specifically, the online monitoring components include influent monitoring components and effluent monitoring components; The inlet water monitoring component is integrated and installed in the second water supply circuit on the inlet header pipe, which is adjacent to the inlet flange of the electric desalination module. It includes a resistivity meter for real-time monitoring and transmission of the inlet water resistivity of the electric desalination module. The effluent monitoring component, integrated and installed in the second water supply circuit on the effluent header pipe immediately downstream of the effluent flange of the electric desalination module, includes: A resistivity meter is used to monitor and transmit the resistivity of the effluent from the electrically driven desalination module in real time. An online silicon content analyzer, employing the principles of ultraviolet-visible spectroscopy or molybdate colorimetry, is used for continuous monitoring of silicon content in effluent. An online total organic carbon analyzer, employing the principles of ultraviolet oxidation-conductivity detection or thin-film infrared detection, is used to continuously monitor the total organic carbon concentration in effluent.

[0031] It is understandable that water quality disturbances will occur when the second loop's own fine treatment unit (i.e., the electrically driven desalination module) is nearing or reaching its processing limit. This indicates that the influent water quality of the entire equipment is deteriorating or the pretreatment process efficiency is declining. If not monitored and addressed simultaneously, the influent water quality of the first loop may also deteriorate in the same way soon. In addition, when water quality disturbances occur in the second loop (such as resin saturation or the need for regeneration), the flow resistance and product water flow rate of its electrically driven desalination module will change drastically. If there is any pressure imbalance between the first and second loops at this time (even with isolation components, it is difficult to completely avoid instantaneous pressure differences under dynamic operating conditions), the pressure fluctuations in the second loop may be transmitted through the pipeline network, causing unstable water supply pressure in the first loop. For silicon wafer cleaning processes, instantaneous fluctuations in flow rate and pressure may lead to uneven cleaning and particle residue, directly affecting yield. While the probability of seal failure or internal leakage in the isolation and anti-cross-flow components is low, the potential risk of contaminants back-permeating or leaking into the first loop network still exists in extreme cases where the water quality in the second loop deteriorates significantly and there is a large pressure difference with the first loop. If such water penetration occurs, it will directly contaminate the entire high-purity water network of the first loop, causing catastrophic batch product losses. Therefore, this invention treats disturbance signals in the second loop as an opportunity for equipment collaborative optimization. Through intelligent scheduling, the potential crisis of the second loop disturbance affecting the first loop is transformed into a low-risk maintenance event, thereby merging the two parallel subsystems into a smart and interconnected whole.

[0032] Specifically, the controller determines whether a water quality disturbance has occurred based on monitoring data from the second water supply circuit, including: In response to the effluent silica content exceeding the silica content threshold, a water quality disturbance is identified, the water supply ratio of the second water supply circuit is reduced, and the salt release phase of the electrically driven desalination module is initiated; during implementation, the silica content threshold must be strictly controlled within 0.1 ppt (10 -13 To prevent silicon ions from depositing on the equipment surface or contaminating the primary circuit through pipeline backflow (g / L), this threshold is referenced to the silicon content limit for secondary water in the SEMIF40 standard.

[0033] In response to the effluent silica content not exceeding the silica content threshold, the resistivity difference is calculated based on the influent resistivity and effluent resistivity (understandably, higher resistivity indicates better water quality; resistivity difference = effluent resistivity - influent resistivity; influent resistivity directly reflects the initial ion content of the raw water, while effluent resistivity reflects the residual ion content after desalination; the difference between the two quantifies the desalination efficiency of the electrically driven desalination module). This, combined with the effluent total organic carbon concentration, determines whether water quality disturbance monitoring conditions are triggered. Furthermore, based on the trigger duration of the water quality disturbance monitoring conditions, it is determined whether water quality disturbance has occurred in the second water supply circuit, including: Based on the determination result that the trigger duration is greater than or equal to the preset trigger duration, it is determined that a water quality disturbance has occurred in the second water supply circuit. It is understandable that the preset trigger duration is usually set to 1 minute to eliminate accidental fluctuation interference. Factors such as water flow impact in the pipeline and errors in monitoring instruments may cause parameter deviations for a short period of time (<1 minute). If it is directly determined as a disturbance, it will cause the controller to adjust frequently, affecting the stability of the water supply. Among them, the water quality disturbance monitoring conditions are that the resistivity difference is lower than the resistivity difference threshold and / or the total organic carbon concentration in the effluent is higher than the organic carbon concentration threshold. In practice, under normal operating conditions, the inlet water resistivity should be between 15 MΩ·cm and 18 MΩ·cm, and the outlet water resistivity should be between 12 MΩ·cm and 15 MΩ·cm. Therefore, the resistivity difference threshold is usually between 3 MΩ·cm and 5 MΩ·cm, and preferably set to 4 MΩ·cm. In practice, referring to the TOC limit of secondary ultrapure water in the SEMI F40 standard, 50ppb is the highest acceptable organic concentration for general rinsing processes: if this threshold is exceeded, organic matter will form residues on the silicon wafer surface, affecting the adhesion of photoresist and the consistency of subsequent processes.

[0034] Understandably, silicon content is a specific and potentially fatal contaminant in silicon wafer production. It is highly hazardous, difficult to remove, and easily accumulates, thus being set as the highest priority criterion. No additional verification time is required. The controller collects silicon content data from the outlet of the electric desalination module in the second water supply loop in real time and compares it directly with the corresponding threshold. If the detected value exceeds the standard, it is immediately identified as a water quality disturbance, and the outlet valve of the second water supply loop is immediately closed to suspend water supply to the point of use. Simultaneously, the bypass valve of the loop is opened to directly discharge the high-silicon water into the wastewater treatment system, completely preventing the spread of pollution. Maintaining the closed state, the controller continues to collect silicon content data from the outlet of the electric desalination module, with a 30-second verification period. If the silicon content drops below the threshold within 30 seconds, it is determined to be an occasional fluctuation, and the vent valve is closed and water supply is restored. If the silicon content remains above the threshold within 30 seconds, it is confirmed to be actual contamination caused by resin adsorption saturation, and the regeneration process begins. At this time, the salt release stage of the electric desalination module is activated, and the connecting valve between the module and the second water supply circuit is closed to ensure that the highly polluted water generated during the regeneration process only circulates within the module and is discharged through the concentrate channel, without flowing into the main water supply pipeline. During regeneration, the pulse duty cycle (adjusted to 60%–70%) and frequency (adjusted to 80kHz–10kHz) can be simultaneously increased to enhance silicon ion desorption efficiency and shorten the regeneration time. The controller not only adapts to the specific needs of silicon wafer production by prioritizing silicon content, solving the defect of indiscriminate judgment of existing technical indicators, but also ensures the accuracy of the judgment result by using dual indicators and multiple constraints of continuous triggering time. The judgment process has a small computational load and can adapt to water quality fluctuations in real time.

[0035] Specifically, the essence of the influent resistivity being lower than the resistivity difference threshold is that the high influent ion concentration leads to an increase in the desalination load of the electric desalination module. If the effective action time of the electric field with the original duty cycle is insufficient, it will be difficult to fully adsorb the excess ions in the water, resulting in excessive ion residue in the effluent and affecting the water quality of the second water supply circuit. The role of the pulse duty cycle is to control the effective action time of the electric field (duty cycle = pulse energizing time / total cycle time). Increasing the duty cycle can prolong the adsorption time of the electric field on ions: on the one hand, it can match the desalination requirements of influent with high ion concentration, enhance the synergistic adsorption effect of uniform particle ion exchange resin and electric field, and ensure that excess ions are fully captured; on the other hand, there is no need to increase the voltage, and the desalination efficiency can be improved simply by extending the action time, avoiding plate polarization and energy waste caused by high voltage. At the same time, it fits the mass transfer characteristics of the cross-flow structure, prevents ions from accumulating in the flow channel, and ensures that the effluent water quality is stable and meets the standards.

[0036] Specifically, an excessive total organic carbon (TOC) concentration in the effluent means that organic matter and its decomposition products in the water have not been effectively removed. These substances have small molecular size and slow migration rate, making them easy to adsorb and retain on the surface of uniform particle resin. Under normal frequencies, they are difficult to migrate quickly to the concentrate channel. The role of pulse frequency is to control the alternation speed of the electric field. Increasing the frequency can accelerate the alternation rhythm of the electric field direction: firstly, it can break the boundary layer resistance of organic decomposition products, reduce their residence time on the resin and electrode surface, and promote their discharge with the concentrate; secondly, the high-frequency alternating electric field can enhance the polarization effect of organic matter, making it easier for it to be intercepted and separated by ion-selective permeation membranes, thereby improving the removal efficiency.

[0037] In practice, to cope with water quality disturbances, the electric desalination module needs to start regeneration (salt release). Regeneration is a process that consumes a lot of water and electricity and may produce high-concentration waste liquid. This will have a concentrated impact on the water production capacity of the pretreatment unit (such as reverse osmosis and desalination unit) shared by all equipment and the wastewater treatment capacity of the plant system. If regeneration happens to coincide with the peak water consumption of the first loop, this resource competition may lead to insufficient water supply or water pressure drop in the first loop, resulting in a water-grabbing situation.

[0038] Specifically, the adjusted pulse waveform parameters (duty cycle and frequency) directly determine the desalination efficiency and resin saturation rate of the electric desalination module. Increasing the duty cycle prolongs the effective duration of the electric field, increases the desalination depth, and delays resin saturation. Increasing the frequency accelerates the migration rate of organic matter and ions, reduces adsorption retention, and similarly prolongs the effective working time of the resin. Therefore, by adjusting the parameters, the theoretical water production cycle from the current state to adsorption saturation can be accurately calculated, thereby determining the expected regeneration time. This determination can be achieved using engineering calculation methods or specialized water treatment simulation software, both of which are existing technologies and will not be elaborated further.

[0039] Understandably, in silicon wafer production, the peak water usage period of the first water supply circuit requires extremely high water quality stability. The regeneration stage of the electric desalination module is accompanied by a sharp increase in ion concentration. If this overlaps with the peak period, water quality may penetrate due to fluctuations in pipeline pressure differential, contaminating the first circuit. Therefore, it is necessary to determine whether to stagger the peak period by matching the regeneration time point with the peak period. If there is an overlap (i.e., the expected regeneration time point is during the peak water usage period of the first water supply circuit), staggered scheduling is implemented to avoid conflicts between regeneration contamination and peak water usage. If there is no overlap (i.e., the expected regeneration time point is not during the peak water usage period of the first water supply circuit), staggered scheduling is not implemented to reduce unnecessary parameter adjustments and energy waste, and to balance water quality safety and water supply economy.

[0040] In implementation, the process of determining several low-water-use periods and several high-water-use periods of the first water supply circuit includes: (1) The controller acquires historical water-use data from the flow sensor on the outlet side of the terminal filter unit of the first water supply circuit. The acquisition period is set to 30 days, and the data granularity is 1 minute / strip. The data includes timestamps and real-time flow values ​​(excluding data from abnormal periods such as equipment maintenance and shutdown, i.e., data with a flow of 0 or less than 10% of the normal minimum flow), and retains valid production period data; (2) Divide the 24 hours of each day into 24 time windows with 1 hour as the unit, including 0:00-1:00, 1:00-2:00, ..., 23:00-24:00, and calculate the average flow value of each time window over 30 days; (3) Calculate the 90th percentile (denoted as Q) of the average flow of all valid time windows. 90 ) and the 50th percentile (denoted as Q) 50 ), where Q 90 As a peak flow threshold, Q 50 As a threshold for low-flow rate; (4) If the average daily flow rate of a certain time window is ≥ Q 90 If two or more consecutive adjacent time windows meet this condition, they are combined and determined to be continuous peak water usage periods; if the average daily flow rate of a certain time window is ≤ Q 50 If two or more consecutive adjacent time windows meet the condition, they are combined and judged as continuous low water usage periods; (5) Repeat the above steps every 7 days, recalculate the flow threshold and peak and off-peak periods based on the latest 30-day historical data, adapt to the changes in water usage patterns caused by production process adjustments, and ensure the real-time effectiveness of the judgment results.

[0041] It is understandable that the regeneration time point is the specific time when the ion exchange resin in the electrically driven desalination module is close to saturation and its desalination capacity is about to fail, at which point the controller starts the salt release stage (i.e., resin regeneration). Therefore, the larger the time difference, the longer the time before the next low point, and the slower the saturation rate is required. This requires reducing the duty cycle or frequency to weaken the effect of the electric field (reducing the duty cycle reduces the effective adsorption time of the electric field, and reducing the frequency reduces the ion migration rate). The larger the time difference, the greater the reduction should be to make the saturation rate slower. In practice, (1) if the duty cycle has been increased due to water quality disturbance, only the frequency is adjusted here; (2) if the frequency has been increased, only the duty cycle is adjusted here; In specific implementation: when the time difference is > 2h, the current duty cycle is reduced by 15% to 20% or the current frequency is reduced by 3kHz to 4kHz; when 1h < time difference ≤ 2h, the current duty cycle is reduced by 10% to 15% or the current frequency is reduced by 2kHz to 3kHz; when 0.5h < time difference ≤ 1h, the current duty cycle is reduced. 5%~10% or lower the current frequency by 2kHz; when the time difference is ≤0.5h, lower the current duty cycle by 5% or lower the current frequency by 1kHz; (3) when the duty cycle and frequency have been increased simultaneously due to water quality disturbance, a small-amplitude, alternating downward adjustment strategy should be adopted, that is, first lower the duty cycle, then lower the frequency, and cycle until the time difference requirement is met. Each downward adjustment should not exceed 10% (duty cycle) or 2kHz (frequency), and always maintain a duty cycle ≥30% and a frequency ≥1kHz.

[0042] Specifically, the water isolation and anti-cross-flow component is installed on the cross-pipe connecting the first water supply circuit and the second water supply circuit, including: Two electrically operated shut-off valves, labeled as the first shut-off valve and the second shut-off valve respectively, are connected in series in the cross pipeline along the water flow direction to form a physical isolation section; A relief valve, the inlet of which is connected to the physical isolation section between the first shut-off valve and the second shut-off valve, and the outlet of which is connected to the drainage equipment; A differential pressure sensor is used to measure the real-time pressure difference between the first water supply circuit and the second water supply circuit; The controller is connected to the differential pressure sensor, two electrically operated shut-off valves, and the relief valve, and is further configured to execute the following safety linkage logic: Real-time monitoring of pressure difference data returned by the differential pressure sensor; If the absolute value of the pressure difference exceeds the preset safety threshold range, an isolation command is generated, controlling the first and second shut-off valves to close simultaneously, and synchronously controlling the relief valve to open, thereby emptying any cross-flowing water that may exist in the physical isolation section. In practice, the safety threshold range is 0.1MPa to 0.3MPa. If the pressure difference exceeds the safety threshold (e.g., >0.3MPa or <0.1MPa), it may cause water in the low-pressure circuit to be back-drawn by the high-pressure circuit, or water in the highly polluted circuit to actively flow back.

[0043] In addition, the isolation command can also be actively triggered by the controller in response to a disturbance in the second water supply circuit where the silicon content exceeds the standard or a water quality disturbance that cannot be eliminated.

[0044] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

[0045] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A dual-channel ultrapure water system for silicon wafer production, comprising at least a raw water pretreatment unit, a reverse osmosis unit, and a desalination unit, characterized in that, Also includes: A diversion unit is installed on the product water side of the desalination unit to divert the product water to the first water supply circuit and the second water supply circuit. The first water supply circuit is used for critical cleaning and to supply water to the final rinsing point. Along its water flow direction, it includes an ultraviolet treatment section, a polishing section, a degassing unit, an ultrafiltration unit, and a terminal filtration unit. The second water supply circuit is used for general rinsing and supplying water to the equipment's water replenishment points, and is equipped with an electric desalination module; An isolation and anti-cross-flow component is installed between the first water supply circuit and the second water supply circuit; An online monitoring component is installed in the second water supply circuit to acquire monitoring data of the second water supply circuit, the monitoring data including inlet water resistivity, outlet water resistivity, silicon content and total organic carbon; The controller is configured to determine whether water quality disturbance has occurred in the inlet water of the second water supply circuit based on the monitoring data of the second water supply circuit, adjust the pulse waveform parameters of the electric desalination module in response to the occurrence of water quality disturbance, and perform staggered scheduling of the water production stage and the salt release stage of the second water supply circuit after adjusting the pulse waveform parameters.

2. The dual-channel ultrapure water equipment for silicon wafer production according to claim 1, characterized in that, The electrically driven desalination module has a cross-flow structure, including a filling region filled with ion exchange resin of uniform particle size, an electrode plate assembly that cooperates with the filling region, and a high-frequency pulse power supply unit connected to the electrode plate assembly. The pulse waveform parameters output by the high-frequency pulse power supply unit include frequency and duty cycle.

3. The dual-channel ultrapure water equipment for silicon wafer production according to claim 1, characterized in that, The online monitoring components include an influent monitoring component and an effluent monitoring component; The water inlet monitoring component is located at the water inlet of the electrically driven desalination module in the second water supply circuit, and includes a resistivity meter; The effluent monitoring component is located at the outlet of the electrically driven desalination module in the second water supply circuit, and includes a resistivity meter, a silicon content monitor, and an online total organic carbon analyzer.

4. The dual-channel ultrapure water equipment for silicon wafer production according to claim 1, characterized in that, The controller determines whether a water quality disturbance has occurred based on monitoring data from the second water supply circuit, including: In response to the water silica content being higher than the silica content threshold, a water quality disturbance is determined and the outlet valve of the second water supply circuit is closed; In response to the effluent silicon content not exceeding a silicon content threshold, the resistivity difference is calculated based on the influent resistivity and effluent resistivity. This difference, combined with the effluent total organic carbon concentration, determines whether a water quality disturbance monitoring condition has been triggered. Furthermore, based on the trigger duration of the water quality disturbance monitoring condition, it is determined whether a water quality disturbance has occurred in the second water supply circuit, including: Based on the determination result that the trigger duration is greater than or equal to the preset trigger duration, it is determined that a water quality disturbance has occurred in the second water supply circuit; Among them, the water quality disturbance monitoring conditions are that the resistivity difference is lower than the resistivity difference threshold and / or the total organic carbon concentration in the effluent is higher than the organic carbon concentration threshold.

5. The dual-channel ultrapure water equipment for silicon wafer production according to claim 1, characterized in that, The controller responds to the situation where the effluent silica content is not higher than the silica content threshold and a water quality disturbance occurs, by adjusting the pulse waveform parameters of the electrically driven desalination module according to the triggering cause of the water quality disturbance, specifically including: In response to the triggering cause being that the resistivity of the inlet water is lower than the resistivity difference threshold, the duty cycle of the pulse waveform is increased; In response to the triggering cause being that the total organic carbon concentration in the effluent is higher than the organic carbon concentration threshold, the frequency of the pulse waveform is increased.

6. The dual-channel ultrapure water equipment for silicon wafer production according to claim 5, characterized in that, The controller calculates the current theoretical water production cycle and the expected regeneration time point of the electrically driven desalination module based on the adjusted pulse waveform parameters, wherein: In response to the expected regeneration time point falling during the peak water usage period of the first water supply circuit, it is determined to implement off-peak scheduling.

7. The dual-channel ultrapure water equipment for silicon wafer production according to claim 6, characterized in that, The controller acquires historical water usage data of the first water supply circuit to determine several low-water-use periods and several high-water-use periods of the first water supply circuit.

8. The dual-channel ultrapure water equipment for silicon wafer production according to claim 7, characterized in that, The controller identifies the next low water usage period of the first water supply circuit and records it as the target period, and generates a scheduling instruction to adjust the start time of the salt release phase of the electric desalination module of the second water supply circuit to the target period.

9. The dual-channel ultrapure water equipment for silicon wafer production according to claim 8, characterized in that, The controller generates the scheduling instructions based on the following processes: Calculate the time difference between the expected regeneration time point and the start time of the target time period; The duty cycle or frequency of the pulse waveform is adjusted based on the time difference to reduce the saturation rate of the ion exchange resin. The time difference is negatively correlated with the duty cycle or the frequency.

10. The dual-channel ultrapure water equipment for silicon wafer production according to claim 1, characterized in that, The isolation and anti-cross-flow component includes a dual electric shut-off valve connected in series on the two water supply circuit connection pipelines and a relief valve and differential pressure sensor located between the two valves. The controller is also configured to determine whether the pressure difference between the two circuits exceeds a safety threshold range based on the data from the differential pressure sensor, and to close the dual electric shut-off valve and open the relief valve based on the determination result that the pressure difference exceeds the safety threshold range.

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