A dynamic soak time control system and method for wet etching of a photovoltaic cell PSG

Abstract

The application provides a dynamic soaking time control system and method for photovoltaic cell PSG wet etching, and the control system comprises a film thickness detector, an abnormal data filtering unit, a batch thickness calculation unit, a dynamic time decision unit and a control unit; the film thickness detector is arranged at a feeding end of a wet etching machine; the film thickness detector and the batch thickness calculation unit are electrically connected with the abnormal data filtering unit; and the batch thickness calculation unit is electrically connected with the dynamic time decision unit. The film thickness detector measures the PSG layer thickness of a silicon wafer piece by piece, the soaking time is dynamically set through a linear mapping relationship based on the average film thickness of the current batch according to the actually measured PSG thickness, the soaking time is adjusted in advance, the etching time is accurately matched with the PSG thickness of the incoming material, the problems of over-etching when the thickness is thin and residual when the thickness is thick in the fixed time mode are fundamentally solved, the efficiency dispersion of the cell piece is significantly reduced, and the yield is improved.

Description

Technical Field

[0001] This invention belongs to the field of photovoltaic cell manufacturing technology, specifically relating to a dynamic immersion time control system and method for PSG wet etching of photovoltaic cells. Background Technology

[0002] In photovoltaic cell manufacturing, phosphorus diffusion is a core process for forming the PN junction, which creates a phosphosilicate glass (PSG) layer on the silicon wafer surface. Subsequent wet etching processes need to completely remove the PSG layer while avoiding excessive etching of the silicon wafer surface. However, the thickness of the PSG layer is not constant—affected by factors such as the uniformity of the temperature field in the diffusion furnace tube, fluctuations in gas flow rate, and differences in loading position, the PSG thickness of different silicon wafers within the same batch varies significantly, with even more pronounced deviations between different batches.

[0003] Traditional PSG wet etching equipment uses a fixed immersion time for the positive etching process, meaning that all silicon wafers are etched for the same duration regardless of the thickness of the incoming PSG. This "one-size-fits-all" control mode has a fundamental flaw: when the PSG on the silicon wafer surface is too thick, the fixed etching time is insufficient to completely remove the PSG, resulting in etching residue. This residual PSG affects subsequent passivation and electrode contact, directly leading to a decrease in cell efficiency. When the PSG on the silicon wafer is too thin, the fixed time leads to over-etching, causing acid to erode the silicon substrate and increasing the recombination of surface defects, which also reduces cell efficiency. This process mismatch caused by thickness fluctuations ultimately manifests as large dispersion in cell efficiency and low yield within batches, becoming a key bottleneck restricting the consistency of yield and efficiency in the mass production of photovoltaic cells.

[0004] Existing technologies already include improved solutions for the wet etching process. For example, Chinese patent CN210379094U proposes a simple water film device for wet etching, which forms a water film protective layer by setting a water spray pipe at the silicon wafer inlet to prevent acid and acid mist from corroding the silicon wafer surface. Chinese patent CN202830170U further discloses a wet etching machine with a blowing device, which uses airflow to accelerate water film diffusion and ensure that the water film completely covers the silicon wafer surface, thereby solving the problems of over-etching and black edges caused by differences in water film diffusion effects on different types of silicon wafers. These solutions focus on the uniformity of water film coverage, but none of them address the issue of the compatibility between PSG thickness fluctuations and etching time, failing to solve the problem of insufficient or over-etching caused by thickness deviations at its source.

[0005] Furthermore, existing control systems generally lack a comprehensive assessment of the overall batch status. Conventional solutions typically adjust parameters based on single-wafer inspection or random sampling results. Anomalies in individual wafers (such as occasional inspection errors or surface contamination on individual wafers) can easily interfere with system judgment, causing unnecessary fluctuations in process parameters. While wafer-by-wafer inspection and independent control can improve accuracy, they would severely reduce production line cycle time, making them impractical in mass production environments. Summary of the Invention

[0006] This invention addresses the technical problem in existing PSG wet etching processes where a fixed etching time cannot adaptively match PSG thickness fluctuations, leading to etching residue on thicker silicon wafers and over-etching on thinner silicon wafers, resulting in inconsistent cell efficiency and reduced yield. The invention provides a PSG wet etching control system and method that combines film thickness detection at the loading end with batch-based dynamic time setting.

[0007] Therefore, the technical solution provided by the present invention is as follows: A dynamic immersion time control system for photovoltaic cell PSG wet etching includes a film thickness detector, an abnormal data filtering unit, a batch thickness calculation unit, a dynamic time decision unit, and a control unit; The film thickness detector is located at the loading end of the wet etching machine. The film thickness detector and the batch thickness calculation unit are both electrically connected to the abnormal data filtering unit. The batch thickness calculation unit is also electrically connected to the dynamic time decision unit. The film thickness measuring instrument measures the PSG layer thickness on the surface of each silicon wafer entering the machine and outputs the thickness data to the abnormal data filtering unit. The abnormal data filtering unit identifies and removes single-wafer thickness data that exceeds a set threshold as abnormal values. The batch thickness unit performs an arithmetic average of the valid thickness data retained in the current batch to obtain the batch average film thickness H. avg The dynamic time decision unit is based on the batch average film thickness H avg Compared with the standard film thickness reference value H S The deviation ΔH was calculated, and the target etching time t was determined. a The control unit receives the target etching time t output by the dynamic time decision unit. a This controls the dwell time of the silicon wafer within the etching tank.

[0008] This invention automatically removes single-wafer thickness data that exceeds the reasonable range by setting up an abnormal data filtering unit, avoiding contamination of the batch average results by individual abnormal silicon wafers or occasional detection errors, ensuring that the control strategy is based on the actual state of the batch, and greatly improving the robustness of the system.

[0009] Furthermore, it also includes a liquid state compensation module, which includes a temperature sensor and a concentration sensor installed in the etching tank. Both the temperature sensor and the concentration sensor are electrically connected to the control unit. The control unit converts the real-time received liquid temperature T and liquid concentration C into a compensation coefficient α and transmits the compensation coefficient α to the dynamic time decision unit. The dynamic time decision unit adjusts the target etching time t based on the compensation coefficient α. a Make corrections.

[0010] This invention introduces temperature and concentration sensors to monitor the state of the etching solution in real time, and converts the changes in the activity of the solution into a compensation coefficient to dynamically correct the etching time. This effectively eliminates the changes in etching rate caused by solution consumption and temperature fluctuations, making the time setting more accurate and further improving batch-to-batch consistency.

[0011] Furthermore, the control unit is a PLC controller or an industrial computer.

[0012] The industrial control computer displays key parameters in real time through a human-machine interface, allowing operators to monitor batch status at any time. Historical data is traceable, facilitating process optimization and anomaly investigation, and providing a data foundation for intelligent manufacturing and big data analysis.

[0013] Furthermore, the film thickness measuring instrument is a spectral reflectometer or a spectral ellipsometer.

[0014] The detector probe of the spectrophotometer is vertically downward or at a set angle aligned with the surface of the silicon wafer during transport, used to measure the thickness of the PSG layer on the surface of the silicon wafer online before it enters the etching tank. The film thickness detector has a spectral acquisition speed of no less than 100 ms / time to match the production line cycle time requirements.

[0015] Furthermore, it also includes a water film auxiliary device and a blowing device. The water film auxiliary device is located at the silicon wafer inlet of the etching tank, and the blowing device is located behind the water film auxiliary device along the silicon wafer conveying direction. The water film auxiliary device includes a water spray pipe with multiple water spray holes for spraying water onto the silicon wafer surface. The air blowing device includes an air supply pipe and an air outlet, with air jet holes facing the silicon wafer to accelerate the uniform spreading of the water film.

[0016] This invention also provides a method for dynamically controlling the immersion time of photovoltaic cell PSG wet etching, which employs the above-mentioned control system and includes the following steps: Step 1) Loading Inspection: As the silicon wafers enter the loading end, the film thickness detector measures the PSG layer thickness on the surface of each silicon wafer and generates a thickness data sequence. Step 2) Abnormal data filtering: The abnormal data filtering unit receives thickness data, determines data that exceeds the threshold of the reasonable thickness range as abnormal values ​​and removes them, and does not participate in the subsequent batch average calculation; Step 3) Batch average thickness calculation: Taking 4-5 basket batches from the machine operation as a unit, the batch thickness calculation unit performs an arithmetic average of the retained effective thickness data to obtain the batch average film thickness H. avg ; Step 4) Dynamic Time Decision: The dynamic time decision unit calculates the deviation ΔH=H avg -H S According to the linear mapping relationship t a =t S +kΔH; Among them, t S The baseline immersion time corresponds to the standard film thickness, and k is the linear mapping coefficient; Step 5) Etching execution: The control unit receives the target etching time t a Controlling the residence time of the silicon wafer within the positive etching groove. a Move out after time; Step 6) Washing and drying: After etching is completed, the sample is washed in a cleaning tank and then dried.

[0017] The method of this invention uses batch average rather than single-wafer extreme values ​​for fault tolerance: the machine operation unit consists of 4-5 baskets as a batch, and the arithmetic mean H of the film thickness of all wafers in the batch is taken. avg Do not use the maximum or minimum value of a single chip, or the independent distribution time of a single chip, to avoid abnormal chips interfering with the entire batch process.

[0018] Furthermore, step 4) is preceded by a step of collecting drug solution state parameters: Temperature and concentration sensors collect the temperature T and concentration C of the chemical solution in the etching tank in real time and send them to the control unit. The control unit converts the collected values ​​into a compensation coefficient α=f(T,C). In step 4), the dynamic time decision unit incorporates the compensation coefficient α into the calculation, and the corrected etching time is t. a =α(t S +kΔH).

[0019] Furthermore, in step 4), when the calculated target etching time t a Exceeding the preset safe time interval [t] min , t max When [the boundary value is specified], it will be automatically output as a boundary value.

[0020] Furthermore, in step 2), the abnormal data filtering unit is also used to count the number and proportion of abnormal data, and output an alarm signal to the machine control system when the abnormal proportion exceeds the preset warning value.

[0021] Furthermore, in step S5, before the silicon wafer enters the etching tank, the water film auxiliary device sprays pure water onto the surface of the silicon wafer to form a protective water film, and the blowing device accelerates the water film to spread evenly with airflow, ensuring that the water film completely covers the surface of the silicon wafer before it enters the etching tank.

[0022] The beneficial effects of this invention are as follows: This invention measures the PSG layer thickness on the surface of silicon wafers one by one using a film thickness measuring instrument. The film thickness of each cell is measured online at the PSG loading end. Based on the measured PSG thickness and the average film thickness of the current batch, the etching immersion time is dynamically set through a linear mapping relationship. The immersion time is pre-adjusted to ensure that the etching time is precisely matched with the incoming PSG thickness. This fundamentally solves the problem of over-etching when the thickness is too thin and residue when it is too thick in the fixed time mode, significantly reducing the efficiency dispersion of the cells and improving the yield. Attached Figure Description

[0023] Figure 1 This is a block diagram illustrating the system principle of the present invention.

[0024] Explanation of reference numerals in the attached figures: 1. Film thickness detector; 2. Abnormal data filtering unit; 3. Drug solution state compensation module; 4. Batch thickness calculation unit; 5. Dynamic time decision unit; 6. Control unit. Detailed Implementation

[0025] The following specific embodiments illustrate the implementation of the invention. Those skilled in the art can easily understand other advantages and effects of the invention from the content disclosed in this specification.

[0026] Exemplary embodiments of the invention are now described; however, the invention may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided to fully and completely disclose the invention and to fully convey its scope to those skilled in the art. The terminology used in the exemplary embodiments is not intended to limit the invention.

[0027] Unless otherwise stated, the terms used herein (including technical terms) have their common meaning as understood by one of ordinary skill in the art. Furthermore, it is understood that terms defined in commonly used dictionaries should be understood to have a meaning consistent with the context of their relevant field, and not to be interpreted as having an idealized or overly formal meaning.

[0028] Example 1 This invention provides a dynamic immersion time control system for wet etching of photovoltaic cells using PSG, including a film thickness detector, an abnormal data filtering unit, a batch thickness calculation unit, a dynamic time decision unit, and a control unit; The film thickness detector is located at the loading end of the wet etching machine. The film thickness detector and the batch thickness calculation unit are both electrically connected to the abnormal data filtering unit. The batch thickness calculation unit is also electrically connected to the dynamic time decision unit. The film thickness measuring instrument measures the PSG layer thickness on the surface of each silicon wafer entering the machine and outputs the thickness data to the abnormal data filtering unit. The abnormal data filtering unit identifies and removes single-wafer thickness data that exceeds a set threshold as abnormal values. The batch thickness unit performs an arithmetic average of the valid thickness data retained in the current batch to obtain the batch average film thickness H. avg The dynamic time decision unit is based on the batch average film thickness H avg Compared with the standard film thickness reference value H S The deviation ΔH was calculated, and the target etching time t was determined. a The control unit receives the target etching time t output by the dynamic time decision unit. a This controls the dwell time of the silicon wafer within the etching tank.

[0029] like Figure 1 As shown, the output of the film thickness detector of the present invention is electrically connected to an abnormal data filtering unit, the output of the abnormal data filtering unit is electrically connected to a batch thickness calculation unit, the output of the batch thickness calculation unit is electrically connected to a dynamic time decision unit, and the output of the dynamic time decision unit is electrically connected to a control unit.

[0030] This invention measures the PSG layer thickness on the surface of silicon wafers one by one using a film thickness measuring instrument. The film thickness of each cell is measured online at the PSG loading end. Based on the measured PSG thickness and the average film thickness of the current batch, the etching immersion time is dynamically set through a linear mapping relationship. The immersion time is pre-adjusted to ensure that the etching time is precisely matched with the incoming PSG thickness. This fundamentally solves the problem of over-etching when the thickness is too thin and residue when it is too thick in the fixed time mode, significantly reducing the efficiency dispersion of the cells and improving the yield.

[0031] Example 2 Based on Example 1, this example provides a dynamic immersion time control system for photovoltaic cell PSG wet etching, and also includes a chemical solution state compensation module. The chemical solution state compensation module includes a temperature sensor and a concentration sensor disposed in the etching tank. The temperature sensor and the concentration sensor are both electrically connected to the control unit. The control unit converts the real-time received chemical solution temperature T and chemical solution concentration C into a compensation coefficient α, and transmits the compensation coefficient α to the dynamic time decision unit. The dynamic time decision unit adjusts the target etching time t based on the compensation coefficient α. a Make corrections.

[0032] This invention introduces temperature and concentration sensors to monitor the state of the etching solution in real time, and converts the changes in the activity of the solution into a compensation coefficient to dynamically correct the etching time. This effectively eliminates the changes in etching rate caused by solution consumption and temperature fluctuations, making the time setting more accurate and further improving batch-to-batch consistency.

[0033] Example 3 This embodiment provides a method for dynamically controlling the immersion time of photovoltaic cell PSG wet etching, including the following steps: Step 1) Loading Inspection: As the silicon wafers enter the loading end, the film thickness detector measures the PSG layer thickness on the surface of each silicon wafer and generates a thickness data sequence. Step 2) Abnormal data filtering: The abnormal data filtering unit receives thickness data, determines data that exceeds the threshold of the reasonable thickness range as abnormal values ​​and removes them, and does not participate in the subsequent batch average calculation; Step 3) Batch average thickness calculation: Taking 4-5 basket batches from the machine operation as a unit, the batch thickness calculation unit performs an arithmetic average of the retained effective thickness data to obtain the batch average film thickness H. avg ; Step 4) Dynamic Time Decision: The dynamic time decision unit calculates the deviation ΔH=H avg -H S According to the linear mapping relationship t a =t S +kΔH; Among them, t S The baseline immersion time corresponds to the standard film thickness, and k is the linear mapping coefficient; Step 5) Etching execution: The control unit receives the target etching time t a Controlling the residence time of the silicon wafer within the etching tank (t) a Move out after time; Step 6) Washing and drying: After etching is completed, the sample is washed in a cleaning tank and then dried.

[0034] In this embodiment, the incoming material detection module uses the NXTHelios-rc online spectroreflectometer manufactured by NXT Measuring Technology, Germany. This device has a spectral acquisition speed of less than 100ms, supports online measurement, and matches the production line throughput target.

[0035] The detection probe is installed directly above the conveyor roller at the loading end, at a vertical distance of 50mm from the silicon wafer surface. The batch thickness calculation unit consists of 4 baskets (116 wafers per basket, totaling 464 wafers) per batch. The standard film thickness reference value H... S The wavelength is set to 30~33nm, and the baseline immersion time is t. SThe etching time was set to 315 seconds, and the linear mapping coefficient k was set to 5 seconds / nm. This means that for every 1nm deviation of the PSG thickness from the standard value, the etching time was adjusted by 5 seconds. The etching solution was a mixture of NaOH, additives, and water, with a concentration of 4.4%.

[0036] In a certain production batch, after filtering out abnormal data, the PSG thickness of 464 silicon wafers was found to be valid for 460 wafers. The average film thickness H of the batch was calculated. avg The wavelength is 35nm, the deviation ΔT = +3.5nm, and the dynamic time decision unit calculates t. a = 315 + 3.5 × 5 = 332.5s. This batch of silicon wafers was removed after being immersed in the etching tank for 332.5 seconds. Subsequent testing showed that the PSG on the surface of this batch of silicon wafers was completely removed without any residue or etching marks. The standard deviation of the cell efficiency within the batch decreased by approximately 62% compared to the fixed-time mode.

[0037] Example 4 Based on Example 3, this example provides a dynamic immersion time control method for PSG wet etching of photovoltaic cells, which includes a chemical solution state parameter acquisition step before step 4): Temperature and concentration sensors collect the temperature T and concentration C of the chemical solution in the etching tank in real time and send them to the control unit. The control unit converts the collected values ​​into a compensation coefficient α=f(T,C). In step 4), the dynamic time decision unit incorporates the compensation coefficient α into the calculation, and the corrected etching time is t. a =α(t S +kΔH).

[0038] In this embodiment, a PT100 platinum resistance temperature sensor (measurement accuracy ±0.1℃) and a conductivity sensor (measurement accuracy ±0.5%FS) are installed inside the etching tank.

[0039] The control unit has a built-in compensation model α = (C / C) S ) · exp[E / R · (1 / T S - 1 / T)], where C is the concentration of the drug solution, C S T represents the standard concentration of the drug solution. S The standard temperature is 68℃, T is the temperature of the chemical solution, E is the activation energy of the etching reaction, and R is the gas constant.

[0040] In a certain production batch, the batch average membrane H avg Given a wavelength of 28nm, ΔT = -6.5nm, the basic calculation t... S+ k·ΔT = 315 - 6.5×5 = 282.5s. Simultaneously, the measured temperature T of the drug solution is 67.5℃ (lower than the standard temperature of 68℃), the measured concentration C is 95% of the standard concentration, and the compensation coefficient α is calculated to be 0.92. The dynamic time decision unit outputs the corrected t. a = 0.92 × 282.5 = 259.9s.

[0041] After etching for 259.9 seconds, the PSG in this batch of silicon wafers was completely removed, and the surface smoothness was good. In contrast, with the uncompensated method, if etching were continued for 282.5 seconds when the reagent activity was low, the actual removal amount would be too large, posing a slight risk of over-etching; while the fixed-time mode (315 seconds) resulted in etching residue due to the thicker PSG and lower reagent activity. The reagent compensation method in this embodiment effectively avoided the above two risks, achieving a batch yield of 99.56%.

[0042] Example 5 Based on Example 3, this example provides a dynamic immersion time control method for wet etching of photovoltaic cells using PSG. In step 4), when the calculated target etching time t... a Exceeding the preset safe time interval [t] min ,t max When [the boundary value is specified], it will be automatically output as a boundary value.

[0043] In this embodiment, the abnormal data filtering unit has a built-in threshold for a reasonable thickness range [T]. l , T h [25nm, 38nm]. In a certain production batch, among 464 silicon wafers, the PSG thickness measurement data for 40 wafers were between 22nm and 23nm, exceeding the reasonable range. These were automatically marked and removed by the abnormal data filtering unit. The batch average film thickness H was calculated from the 424 valid data wafers. avg The wavelength is 29nm, ΔH = -2.5nm, t a = 315 - 2.5×5 = 302.5s.

[0044] Example 6 Based on Example 3, this example provides a dynamic immersion time control method for PSG wet etching of photovoltaic cells. In step 5), before the silicon wafer enters the etching tank, a water film auxiliary device sprays pure water on the surface of the silicon wafer to form a protective water film, and a blowing device accelerates the water film to spread evenly with airflow to ensure that the water film completely covers the surface of the silicon wafer before it enters the etching tank.

[0045] The water film device is located at the silicon wafer inlet of the etching tank and includes a water spray pipe and a water inlet pipe. The water spray pipe is equipped with multiple water spray holes, which spray pure water onto the surface of the silicon wafer conveyed by the rollers to form a protective water film on the silicon wafer surface.

[0046] The air blowing device is located behind the water film device and includes an air supply pipe and an air outlet. The air outlet has an air jet hole facing the silicon wafer. The air jet direction is 45° with the silicon wafer's travel direction. The airflow is used to accelerate the uniform spread of the water film and ensure that the water film completely covers the surface of the silicon wafer.

[0047] Under the premise of complete water film coverage, the dynamic time control system calculates t based on the average film thickness of the batch. a Etching is performed. The water film protection effectively prevents unintended corrosion of the silicon wafer surface by acid and acid mist, while dynamic time control precisely matches the time required for PSG removal; the two work synergistically.

[0048] Comparative Example 1 Compared with Comparative Example 1 and Example 3, the difference is that the soaking time was fixed at 315s.

[0049] Comparative Example 2 Compared to Example 5, Comparative Example 2 differs in that it does not include an anomaly filtering scheme. Instead, it incorporates all 22nm, 23nm, and 24nm wavelengths into the average calculation, thus lowering the batch average film thickness to approximately 26nm. The calculated t... a The time was 287.5 seconds, which is 15 seconds longer than the actual required time, causing 424 normal silicon wafers to face the risk of over-corrosion.

[0050] To verify the technical effect of the present invention, experiments were conducted on Examples 3-5 and the comparative examples, and the results are shown in Table 1.

[0051] The experimental batches for both the embodiments and comparative examples of this invention are 30 batches (batch sample size: 4 baskets = 464 pieces).

[0052] Comparing Example 3 and Comparative Example 1, Example 3, which employs dynamic time control, achieved a batch yield of 99.35%, which is greater than the 98.27% of Comparative Example 1. Comparing Example 4 and Example 3, Example 4, which employs a dynamic control scheme with drug solution state compensation, achieved a batch yield of 99.56%, which is higher than the 99.35% of Example 3. Comparing Example 5 and Comparative Example 2, it can be seen that the batch yield of Comparative Example 2 is lower than that of Example 5, at only 91.37%, because no abnormal data filtering was performed.

[0053] Experimental data show that the proposed solution significantly outperforms the traditional fixed-time solution in key indicators such as PSG residue rate, over-trace rate, efficiency consistency, and batch yield. The activation of the chemical solution state compensation module further improves yield and reduces surface defect density. The abnormal data filtering unit triggered anomaly rejection 19 times across 30 experimental batches, involving a total of 47 abnormal wafers, all of which were effectively filtered without interfering with batch control decisions, verifying the system's anti-abnormal interference capability.

[0054] The examples above are merely illustrative of the invention and do not constitute a limitation on the scope of protection of the invention. Any design that is the same as or similar to the invention falls within the scope of protection of the invention.

Claims

1. A dynamic immersion time control system for wet etching of photovoltaic cells using PSG, characterized in that, It includes a film thickness measuring instrument, an abnormal data filtering unit, a batch thickness calculation unit, a dynamic time decision unit, and a control unit; The film thickness detector is located at the loading end of the wet etching machine. The film thickness detector and the batch thickness calculation unit are both electrically connected to the abnormal data filtering unit. The batch thickness calculation unit is also electrically connected to the dynamic time decision unit. The film thickness measuring instrument measures the PSG layer thickness on the surface of each silicon wafer entering the machine and outputs the thickness data to the abnormal data filtering unit. The abnormal data filtering unit identifies and removes single-wafer thickness data that exceeds a set threshold as abnormal values. The batch thickness unit performs an arithmetic average of the valid thickness data retained in the current batch to obtain the batch average film thickness H. avg The dynamic time decision unit is based on the batch average film thickness H avg Compared with the standard film thickness reference value H S The deviation ΔH was calculated, and the target etching time t was determined. a The control unit receives the target etching time t output by the dynamic time decision unit. a This controls the dwell time of the silicon wafer within the etching tank.

2. The dynamic immersion time control system for photovoltaic cell PSG wet etching according to claim 1, characterized in that, It also includes a liquid state compensation module, which includes a temperature sensor and a concentration sensor installed in the etching tank. The temperature sensor and the concentration sensor are both electrically connected to the control unit. The control unit converts the real-time received liquid temperature T and liquid concentration C into a compensation coefficient α and transmits the compensation coefficient α to the dynamic time decision unit. The dynamic time decision unit adjusts the target etching time t based on the compensation coefficient α. a Make corrections.

3. The dynamic immersion time control system for photovoltaic cell PSG wet etching according to claim 1, characterized in that, The control unit is a PLC controller or an industrial computer.

4. A dynamic immersion time control system for photovoltaic cell PSG wet etching according to claim 1, characterized in that, The film thickness measuring instrument is a spectral reflectometer or a spectral ellipsometer.

5. A dynamic immersion time control system for photovoltaic cell PSG wet etching according to claim 1, characterized in that, It also includes a water film auxiliary device and a blowing device. The water film auxiliary device is located at the silicon wafer inlet of the etching tank, and the blowing device is located behind the water film auxiliary device along the silicon wafer conveying direction. The water film auxiliary device includes a water spray pipe with multiple water spray holes for spraying water onto the silicon wafer surface. The air blowing device includes an air supply pipe and an air outlet, with air jet holes facing the silicon wafer to accelerate the uniform spreading of the water film.

6. A method for dynamically controlling the immersion time of photovoltaic cell PSG wet etching, comprising the dynamic immersion time control system for photovoltaic cell PSG wet etching as described in any one of claims 1 to 5, characterized in that, Includes the following steps: Step 1) Loading Inspection: As the silicon wafers enter the loading end, the film thickness detector measures the PSG layer thickness on the surface of each silicon wafer and generates a thickness data sequence. Step 2) Abnormal data filtering: The abnormal data filtering unit receives thickness data, determines data that exceeds the threshold of the reasonable thickness range as abnormal values ​​and removes them, and does not participate in the subsequent batch average calculation; Step 3) Batch average thickness calculation: Taking 4-5 basket batches from the machine operation as a unit, the batch thickness calculation unit performs an arithmetic average of the retained effective thickness data to obtain the batch average film thickness H. avg ; Step 4) Dynamic Time Decision: The dynamic time decision unit calculates the deviation ΔH=H avg -H S According to the linear mapping relationship t a =t S +kΔH; Among them, t S The baseline immersion time corresponds to the standard film thickness, and k is the linear mapping coefficient; Step 5) Etching execution: The control unit receives the target etching time t a Controlling the residence time of the silicon wafer within the positive etching groove. a Move out after time; Step 6) Washing and drying: After etching is completed, the sample is washed in a cleaning tank and then dried.

7. The method for dynamically controlling the immersion time of photovoltaic cell PSG wet etching according to claim 6, characterized in that, Before step 4), there is also a step for collecting drug solution state parameters: Temperature and concentration sensors collect the temperature T and concentration C of the chemical solution in the etching tank in real time and send them to the control unit. The control unit converts the collected values ​​into a compensation coefficient α=f(T,C). In step 4), the dynamic time decision unit incorporates the compensation coefficient α into the calculation, and the corrected etching time is t. a =α(t S +kΔH).

8. The method for dynamically controlling the immersion time of photovoltaic cell PSG wet etching according to claim 6, characterized in that, In step 4), when the calculated target etching time t a Exceeding the preset safe time interval [t] min , t max When [the boundary value is specified], it will be automatically output as a boundary value.

9. The method for dynamically controlling the immersion time of photovoltaic cell PSG wet etching according to claim 6, characterized in that, In step 2), the abnormal data filtering unit is also used to count the number and proportion of abnormal data, and output an alarm signal to the machine control system when the abnormal proportion exceeds the preset warning value.

10. The method for dynamically controlling the immersion time of photovoltaic cell PSG wet etching according to claim 6, characterized in that, In step S5, before the silicon wafer enters the etching tank, the water film auxiliary device sprays pure water onto the surface of the silicon wafer to form a protective water film, and the blowing device accelerates the water film to spread evenly with airflow, ensuring that the water film completely covers the surface of the silicon wafer before it enters the etching tank.

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