Chained single-side chemical cleaning system for multilayer silicon wafers

Abstract

The invention belongs to the technical field of semiconductors, and relates to a multi-layer silicon wafer chained single-side chemical cleaning system, which comprises a silicon wafer preliminary cleaning module, a silicon wafer drying module, a silicon wafer cleaning module, a silicon wafer cleaning module, a silicon wafer cleaning module and a silicon wafer cleaning module, the cleanliness detection module is used for detecting the cleanliness of the surface of the primarily cleaned polycrystalline silicon wafer; the cleanliness threshold setting module is used for setting a low-cleanliness threshold and a high-cleanliness threshold, and comparing the cleanliness of the surface of the polycrystalline silicon wafer with the low-cleanliness threshold and the high-cleanliness threshold; the secondary backwashing mode selection module is used for selecting a proper secondary backwashing mode for the polycrystalline silicon wafer; the wastewater recycling module is used for recycling clean water after cleaning is finished; and the wastewater cleanliness judgment module selects a proper wastewater circulation mode for the wastewater. The problems that a traditional silicon wafer cleaning mode depends on simple mechanical equipment, the efficiency of the cleaning mode is low, and the cleaning quality is difficult to effectively guarantee can be solved.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductors, and in particular relates to a chain-type single-side chemical cleaning system for multi-layer silicon wafers. Background Art

[0002] In the semiconductor manufacturing industry, polycrystalline silicon wafers play a crucial role; they are not only directly related to the performance and reliability of semiconductor devices, but also serve as a key indicator of a semiconductor manufacturing company's technological prowess and environmental protection capabilities. Traditional silicon wafer cleaning methods rely primarily on manual labor or simple mechanized equipment. This cleaning method is not only inefficient and difficult to adapt to the pace of large-scale production, but also often lacks effective cleaning quality assurance. The subjective errors introduced by manual operation and the technical limitations of mechanized equipment make it difficult to achieve the high cleanliness standards required by modern semiconductor processes.

[0003] With the rapid development of semiconductor technology, the cleanliness requirements for silicon wafers are becoming increasingly stringent. Traditional cleaning methods are no longer able to meet this urgent need, and traditional cleaning processes suffer from serious resource waste. Cleaning fluids and water, key resources in the cleaning process, are often used and subsequently discarded in large quantities. This extensive resource utilization not only increases production costs and reduces the company's economic benefits, but also places a heavy burden on the environment.

[0004] To address the above issues, traditional silicon wafer cleaning methods rely on manual operations or simple mechanized equipment. This cleaning method is not only inefficient and difficult to adapt to the rhythm of large-scale production, but the cleaning quality is often difficult to effectively guarantee. Summary of the Invention

[0005] In order to solve the problem that the traditional silicon wafer cleaning method relies on simple mechanized equipment, which is not only inefficient but also difficult to effectively guarantee the cleaning quality, the present invention provides a multi-layer silicon wafer chain single-sided chemical cleaning system.

[0006] Multi-layer silicon wafer chain single-side chemical cleaning system, including:

[0007] Silicon wafer preliminary cleaning module, used for preliminary cleaning, drying and cooling of polycrystalline silicon wafers;

[0008] Cleanliness detection module, used to detect the cleanliness of the surface of the polysilicon wafer after preliminary cleaning;

[0009] A cleanliness threshold setting module is used to set a low cleanliness threshold and a high cleanliness threshold, and compare the cleanliness of the polysilicon wafer surface with the low cleanliness threshold and the high cleanliness threshold;

[0010] The secondary rewash mode selection module selects the appropriate secondary rewash mode for the polysilicon wafer based on the cleanliness of the polysilicon wafer surface and the size of the low cleanliness threshold and the high cleanliness threshold;

[0011] Wastewater recycling module, used for recycling clean water after cleaning;

[0012] The wastewater cleanliness determination module is used to set the wastewater cleanliness threshold, compare the cleanliness of the wastewater with the wastewater cleanliness threshold, and select the appropriate wastewater circulation mode.

[0013] Preferably, the silicon wafer preliminary cleaning module comprises: a silicon wafer chain cleaning unit;

[0014] A silicon wafer chain cleaning unit, comprising a chain conveyor for transporting polycrystalline silicon wafers, a cleaning tank for carrying the polycrystalline silicon wafers, pure water pouring equipment for injecting pure water into the cleaning tank, cleaning liquid pouring equipment for injecting cleaning liquid into the cleaning tank, and clean water pouring equipment for removing cleaning liquid from the surface of the polycrystalline silicon wafers;

[0015] The chain conveyor is connected to the cleaning tank, and the pure water filling equipment, cleaning liquid filling equipment, and clean water filling equipment are all connected to the cleaning tank; waste liquid recovery equipment for storing used cleaning liquid and waste water recovery equipment for storing used clean water are provided below the cleaning tank.

[0016] Preferably, the silicon wafer preliminary cleaning module further comprises: a silicon wafer rapid drying unit and a silicon wafer rapid cooling unit;

[0017] The silicon wafer rapid drying unit is located at the next process after the silicon wafer chain cleaning unit, and the silicon wafer rapid cooling unit is located at the next process after the silicon wafer rapid drying unit;

[0018] Silicon wafer rapid drying unit, including fan heat drying equipment;

[0019] Silicon wafer rapid cooling unit, including condensate cooling equipment.

[0020] Preferably, detecting the cleanliness of the surface of the polycrystalline silicon wafer after preliminary cleaning comprises the following steps:

[0021] Based on the cleaning batches of polysilicon wafers or specific time intervals, multiple polysilicon wafers are selected as test samples. The CCD visual inspection instrument observes the surface of the test samples and records the number, size, and distribution of contaminants on the surface of the test samples.

[0022] Calculate the cleanliness of the polysilicon wafer surface and satisfy the following formula:

[0023]

[0024] Among them, CI is the cleanliness index of the surface of the polysilicon wafer; N is the number of pollutants per unit area on the surface of the polysilicon wafer; S is the area of the largest pollutant; D is the average distribution density of the pollutants; a and b represent weighting coefficients.

[0025] Preferably, a low cleanliness threshold and a high cleanliness threshold are set, and the cleanliness of the surface of the polysilicon wafer is compared with the low cleanliness threshold and the high cleanliness threshold, including the following steps:

[0026] Set the low cleanliness threshold LCT and the high cleanliness threshold HCT, and compare the cleanliness of the surface of the polysilicon wafer with the low cleanliness threshold and the high cleanliness threshold;

[0027] If CI < LCT, it means that the cleanliness level of the polysilicon wafer is "low";

[0028] If LCT ≤ CI < HCT, it means that the cleanliness level of the polysilicon wafer is "medium";

[0029] If CI ≥ HCT, it means that the cleanliness level of the polysilicon wafer is "high".

[0030] Preferably, the polysilicon wafer selects a suitable secondary re-washing mode, including the following steps:

[0031] When the cleanliness level of the polysilicon wafer is "high", a secondary re-washing mode with a simple method and low cost is adopted: the high-pressure cleaning mode;

[0032] In the high-pressure cleaning mode, high-pressure clean water is sprayed on the polysilicon wafer, and the pollutants on the surface of the polysilicon wafer are removed through the impact of hydrodynamics. Antistatic agents need to be added to the high-pressure clean water, and the clean water after the polysilicon wafer is cleaned is recycled to the wastewater recycling equipment.

[0033] Preferably, the polysilicon wafer selects a suitable secondary re-washing mode, and further includes the following steps:

[0034] When the cleanliness level of the polysilicon wafer is "medium", a more refined secondary re-washing mode is adopted: the chemical agent + ultrasonic cleaning mode;

[0035] In the chemical agent cleaning mode, an organic solvent is used to clean the surface of the polysilicon wafer for the first time; an inorganic acid is used to clean the surface of the polysilicon wafer for the second time; <00​​​​​​​The cleanliness level of polysilicon wafers is "low", so a complex secondary rewashing mode is used: RCA cleaning + ozone microbubble cleaning + vacuum high temperature treatment;

[0039] The RCA cleaning method uses an ammonia-hydrogen peroxide mixture to clean the surface of the polysilicon wafer for the first time; and uses a hydrochloric acid-hydrogen peroxide mixture to clean the surface of the polysilicon wafer for the second time, completely removing organic matter, metal ions and particulate impurities on the polysilicon surface;

[0040] Ozone microbubble cleaning, RCA cleaning method After cleaning, the polysilicon wafer uses the high activity and strong oxidizing properties of ozone to remove organic matter and particulate impurities on the surface of the polysilicon wafer. The ozone microbubble cleaning method forms an atomically smooth oxide film on the surface of the polysilicon wafer;

[0041] Vacuum high temperature treatment, RCA cleaning + ozone microbubble cleaning method After cleaning, the polysilicon wafers are subjected to vacuum high temperature treatment to further remove gases, solvent molecules and solid impurities adsorbed on the surface of the polysilicon wafers.

[0042] Preferably, the wastewater recycling module includes a water pump power circulation device, a wastewater filtration device and a wastewater detection device; the wastewater filtration device is provided at the subsequent process of the wastewater recovery device, the wastewater detection device is provided at the subsequent process of the wastewater filtration device, and the water pump power circulation device is provided at the subsequent process of the wastewater detection device;

[0043] Wastewater filtering equipment is used to filter the clean water after cleaning; wastewater testing equipment is used to test the clean water after filtration; water pump power circulation equipment is used to input the clean water that has passed the test into the clean water filling equipment.

[0044] Preferably, the wastewater selects a suitable wastewater circulation mode, comprising the following steps:

[0045] Set a wastewater cleanliness threshold, compare the cleanliness of the wastewater with the wastewater cleanliness threshold, and select an appropriate wastewater circulation mode for the wastewater of the wastewater recovery equipment; if the cleanliness of the wastewater is less than the wastewater cleanliness threshold, the clean water is judged to be unqualified, otherwise it is qualified;

[0046] If the clean water is judged to be qualified in cleanliness, the clean water is input into the clean water filling equipment; if the clean water is judged to be unqualified in cleanliness, the clean water is input into the condensate refrigeration equipment as condensate.

[0047] In summary, the present invention has the following beneficial technical effects:

[0048] 1. Efficient and precise initial cleaning of polycrystalline silicon wafers not only thoroughly cleans the wafers but also effectively dries and cools them, providing excellent conditions for subsequent steps. The system also combines an advanced cleanliness detection module with a secondary rewash mode selection module to accurately detect the cleanliness of the wafer surface in real time and automatically select the appropriate cleaning mode based on the detection results. This intelligent design not only improves cleaning efficiency but also enables the system to flexibly adjust according to the actual conditions of the wafers.

[0049] 2. To ensure that the cleaning quality of polysilicon wafers meets customer requirements, precise cleanliness control technology is adopted. By setting low and high cleanliness thresholds, the system can accurately determine the cleanliness level of the silicon wafer surface. The system is also equipped with multiple secondary rewash modes, which can perform targeted cleaning according to different cleanliness levels. This not only ensures the cleaning quality of the silicon wafers, but also improves the stability and reliability of the system.

[0050] 3. This system makes a significant contribution to environmental protection by enabling the recycling of clean water after cleaning. The module effectively filters and tests wastewater, ensuring its cleanliness meets recycling requirements. The system also sets a wastewater cleanliness threshold to further ensure wastewater recycling. This design not only reduces wastewater discharge but also minimizes environmental impact, achieving green and sustainable production.

[0051] 4. Through automated cleaning, testing, and wastewater recycling processes, the system achieves efficient and energy-saving production, reducing manual intervention and waste of clean water resources. The system selects the appropriate cleaning mode based on the wafer's cleanliness level, avoiding unnecessary over-cleaning. This intelligent production method reduces production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 The invention discloses a framework diagram of a multi-layer silicon wafer chain single-side chemical cleaning system.

[0053] Figure 2 The invention discloses an execution flow chart of a multi-layer silicon wafer chain single-side chemical cleaning system. DETAILED DESCRIPTION

[0054] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0055] The following is combined with Figure 1-2The preferred embodiments of the present invention are described in detail.

[0056] See attached Figure 1-2 The present invention proposes a multi-layer silicon wafer chain single-side chemical cleaning system, including a silicon wafer preliminary cleaning module, a cleanliness detection module, a cleanliness threshold setting module, a secondary rewash mode selection module, a wastewater recycling module, and a wastewater cleanliness determination module;

[0057] Silicon wafer preliminary cleaning module, used for preliminary cleaning, drying and cooling of polycrystalline silicon wafers;

[0058] Cleanliness detection module, used to detect the cleanliness of the surface of the polysilicon wafer after preliminary cleaning;

[0059] A cleanliness threshold setting module is used to set a low cleanliness threshold and a high cleanliness threshold, and compare the cleanliness of the polysilicon wafer surface with the low cleanliness threshold and the high cleanliness threshold;

[0060] The secondary rewash mode selection module selects the appropriate secondary rewash mode for the polysilicon wafer based on the cleanliness of the polysilicon wafer surface and the size of the low cleanliness threshold and the high cleanliness threshold;

[0061] Wastewater recycling module, used for recycling wastewater after cleaning;

[0062] The wastewater cleanliness determination module is used to set the wastewater cleanliness threshold, compare the cleanliness of the wastewater with the wastewater cleanliness threshold, and select the appropriate wastewater circulation mode.

[0063] In one embodiment of the present invention, the silicon wafer preliminary cleaning module includes a silicon wafer chain cleaning unit, a silicon wafer rapid drying unit, and a silicon wafer rapid cooling unit. The silicon wafer rapid drying unit is provided as a subsequent process to the silicon wafer chain cleaning unit, and the silicon wafer rapid cooling unit is provided as a subsequent process to the silicon wafer rapid drying unit.

[0064] The silicon wafer chain cleaning unit includes a chain conveyor for transporting polycrystalline silicon wafers, a cleaning tank for carrying the polycrystalline silicon wafers, a pure water filling device for injecting pure water into the cleaning tank, a cleaning liquid filling device for injecting cleaning liquid into the cleaning tank, and a clean water filling device for removing cleaning liquid from the surface of the polycrystalline silicon wafers. The chain conveyor is connected to the cleaning tank, and the pure water filling device, cleaning liquid filling device, and clean water filling device are all connected to the cleaning tank.

[0065] Below the cleaning tank is a waste liquid recovery device for storing used cleaning liquid and a waste water recovery device for storing used clean water. The silicon wafer chain cleaning unit has multiple layers, and the multiple layers of silicon wafer chain cleaning units are stacked in a vertical direction.

[0066] Specifically, polysilicon wafers are transported to a cleaning tank via a chain conveyor. First, a pure water filling device injects pure water into the tank, covering and protecting the polysilicon wafers with pure water. Then, a cleaning liquid filling device injects deionized water into the tank as a cleaning liquid for single-sided cleaning. The cleaning liquid is then recovered to a waste liquid recovery device. A clean water filling device then injects clean water to rinse the surface of the polysilicon wafers. The wastewater from the cleaning process is then recovered to the wastewater recovery device.

[0067] Silicon wafer rapid drying unit, including fan heat drying equipment;

[0068] Specifically, the polycrystalline silicon wafers that have been thoroughly cleaned with clean water to remove surface impurities and residues are sent into the fan heat drying equipment. After the equipment is started, strong hot air blows quickly and evenly across the surface of the silicon wafers, using its efficient heat transfer capability to quickly evaporate the moisture on the silicon wafers. This process not only greatly shortens the drying time, but also effectively avoids the corrosion or contamination of the silicon wafers that may be caused by residual moisture.

[0069] Silicon wafer rapid cooling unit, including condensate cooling equipment;

[0070] Specifically, during the hot air drying process, the silicon wafer absorbs a large amount of heat, causing its surface temperature to rise significantly. If the temperature is not cooled in time, the performance and stability of the silicon wafer may be affected.

[0071] Condensate cooling equipment plays a crucial role in this process, precisely and efficiently cooling the hot surfaces of the multicrystalline silicon wafers through circulating condensate. As the condensate absorbs heat from the wafers, its own temperature gradually rises before being cooled again by an external cooling system, forming a closed-loop cycle. This process ensures that the multicrystalline silicon wafers can be cooled evenly and quickly to room temperature.

[0072] In one embodiment of the present invention, detecting the cleanliness of the surface of a polycrystalline silicon wafer after preliminary cleaning includes the following steps:

[0073] Based on the cleaning batches or specific time intervals of the polysilicon wafers, multiple polysilicon wafers are sampled as test samples. The surface of the test samples is observed using a CCD visual inspection instrument, and the number, size, and distribution of contaminants on the test sample surface are recorded. Contaminants include stains, particles, and residual cleaning fluid areas.

[0074] Calculate the cleanliness of the polysilicon wafer surface and satisfy the following formula:

[0075]

[0076] Where, CI is the cleanliness index of the surface of the polysilicon wafer; N is the number of pollutants per unit area on the surface of the polysilicon wafer; S is the area of the largest pollutant; D is the average distribution density of the pollutants; a and b represent weight coefficients, which are determined according to the evaluation of professionals.

[0077] Exemplarily, the number of pollutants N per square centimeter = 5; the area of the largest pollutant S = 100 square microns; the average distribution density of the pollutants D = 0.02 per square centimeter; determined according to the evaluation of professionals, a = 1 and b = 1;

[0078] To calculate the cleanliness of the surface of the polysilicon wafer, substitute it into the following formula,

[0079]

[0080] In one embodiment of the present invention, a low cleanliness threshold and a high cleanliness threshold are set, and the cleanliness of the surface of the polysilicon wafer is compared with the low cleanliness threshold and the high cleanliness threshold, including the following steps:

[0081] The quality inspection department of the company sets the low cleanliness threshold and the high cleanliness threshold according to the quality inspection standards of the customers; the low cleanliness threshold is used to determine the lowest acceptable level of the cleanliness of the silicon wafer; the high cleanliness threshold is used to determine the excellent level of the cleanliness of the silicon wafer; compare the cleanliness of the surface of the polysilicon wafer with the low cleanliness threshold and the high cleanliness threshold.

[0082] Exemplarily, the quality inspection department of the company sets the low cleanliness threshold LCT = 10×10 4 , the high cleanliness threshold HCT = 10×10 6 ;

[0083] If CI < LCT = 10×10 4 , it means that the cleanliness level of the polysilicon wafer is "low";

[0084] If LCT ≤ CI < HCT, it means that the cleanliness level of the polysilicon wafer is "medium";

[0085] If CI ≥ HCT = 10×10 6 , it means that the cleanliness level of the polysilicon wafer is "high".

[0086] In one embodiment of the present invention, according to the size of the cleanliness of the surface of the polysilicon wafer and the low cleanliness threshold and the high cleanliness threshold, a suitable secondary re-washing mode is selected for the polysilicon wafer, including the following steps:

[0087] If CI ≥ HCT, it means that the cleanliness level of the polysilicon wafer is "high", and a secondary re-washing mode with simple method and low cost is adopted: high-pressure cleaning mode;

[0088] High-pressure cleaning mode: Use high-pressure clean water to spray the polysilicon wafers, and remove the pollutants on the surface of the polysilicon wafers through the impact of hydrodynamic force. The electrostatic effect may be generated when high-pressure clean water sprays the polysilicon wafers. Antistatic agents need to be added to the high-pressure clean water to avoid scratches and damages to the polysilicon wafers caused by the pollutants on the surface of the polysilicon wafers as much as possible. The clean water after the cleaning of the polysilicon wafers is recycled to the wastewater recycling equipment.

[0089] If LCT ≤ CI < HCT, it indicates that the cleanliness level of the polysilicon wafers is "medium", and a more refined secondary re-washing mode is adopted: chemical agent + ultrasonic cleaning mode;

[0090] Chemical agent cleaning mode: Use organic solvents such as toluene, acetone, and alcohol to clean the surface of the polysilicon wafers for the first time; use inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, and hydrofluoric acid to clean the surface of the polysilicon wafers for the second time;

[0091] Ultrasonic cleaning mode: Place the polysilicon wafers after chemical agent cleaning mode in the cleaning tank of the ultrasonic equipment, and remove the pollutants on the surface of the polysilicon wafers through the vibration of ultrasonic waves. It should be noted that the power of the ultrasonic equipment should not be too large to avoid scratches and damages to the polysilicon wafers caused by the pollutants on the surface of the polysilicon wafers as much as possible.

[0092] If CI < LCT, it indicates that the cleanliness level of the polysilicon wafers is "low", and a secondary re-washing mode with complex and efficient methods is adopted: RCA cleaning + ozone micro-bubble cleaning + vacuum high-temperature treatment;

[0093] RCA cleaning method: Use ammonia-hydrogen peroxide mixture (APM) to clean the surface of the polysilicon wafers for the first time; use hydrochloric acid-hydrogen peroxide mixture (HPM) to clean the surface of the polysilicon wafers for the second time, thoroughly remove the organic matters, metal ions, and particle impurities on the polysilicon surface, and improve the electrochemical performance of the silicon wafers at the same time;

[0094] Ozone micro-bubble cleaning: For the polysilicon wafers after RCA cleaning method, use the high activity and strong oxidizing property of ozone to remove the organic matters and particle impurities on the surface of the polysilicon wafers. The ozone micro-bubble cleaning method can form an atomically smooth oxide film on the surface of the polysilicon wafers to avoid the re-adsorption of pollutants on the surface of the polysilicon wafers as much as possible;

[0095] Vacuum high-temperature treatment: After the polysilicon wafers are cleaned by RCA cleaning + ozone micro-bubble cleaning method, the polysilicon wafers are subjected to vacuum high-temperature treatment to further remove the gas, solvent molecules, and solid impurities adsorbed on the surface of the polysilicon wafers.

[0096] In one embodiment of the present invention, the wastewater recycling module includes a water pump power circulation device, a wastewater filtration device, and a wastewater detection device. The wastewater filtration device is provided after the wastewater recovery device, the wastewater detection device is provided after the wastewater filtration device, and the water pump power circulation device is provided after the wastewater detection device.

[0097] Wastewater filtering equipment is used to filter the clean water after cleaning; wastewater testing equipment is used to test the clean water after filtration; water pump power circulation equipment is used to input the clean water that has passed the test into the clean water filling equipment.

[0098] Specifically, the clean water after cleaning is pumped to the wastewater filtration equipment for filtering the clean water after cleaning; the clean water after filtration is pumped to the wastewater detection equipment for detecting the clean water after filtration; if the clean water is judged to be qualified in cleanliness, the water pump power circulation equipment inputs the clean water into the clean water filling equipment; if the clean water is judged to be unqualified in cleanliness, the water pump power circulation equipment inputs the clean water into the condensate refrigeration equipment as condensate.

[0099] In one embodiment of the present invention, selecting a suitable wastewater circulation mode for wastewater includes the following steps:

[0100] The company's quality inspection department sets the wastewater cleanliness threshold according to the customer's quality inspection standards, compares the relationship between the cleanliness of the wastewater and the wastewater cleanliness threshold, and selects the appropriate wastewater circulation mode for the wastewater of the wastewater recovery equipment.

[0101] For example, the quality inspection department sets the wastewater cleanliness threshold value as the suspended solids concentration SS = 50 mg / L and the chemical oxygen demand COD = 100 mg / L in accordance with the customer's quality inspection standards. If the cleanliness of the wastewater does not meet one of the suspended solids concentration and the chemical oxygen demand, the clean water is judged to be unqualified, otherwise it is qualified; if the cleanliness of the clean water is judged to be qualified, the clean water is input into the clean water filling equipment; if the cleanliness of the clean water is judged to be unqualified, the clean water is input into the condensate refrigeration equipment as condensate.

[0102] The interface definitions and communication protocols between modules clarify the interface specifications between modules, including: interface name, parameter type, return value, etc., and formulate corresponding communication protocols to ensure that data and information can be transmitted correctly and efficiently between modules.

[0103] The above embodiments are only used to illustrate the technical solutions of the present invention. Although the present invention is described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. Multi-layer silicon wafer chain single-side chemical cleaning system, characterized by: Including: A silicon wafer preliminary cleaning module for preliminarily cleaning, drying, and cooling polysilicon wafers; A cleanliness detection module for detecting the cleanliness of the surface of polysilicon wafers after preliminary cleaning; A cleanliness threshold setting module for setting a low cleanliness threshold and a high cleanliness threshold, and comparing the cleanliness of the surface of polysilicon wafers with the low cleanliness threshold and the high cleanliness threshold; A secondary re-washing mode selection module for selecting a suitable secondary re-washing mode for polysilicon wafers by combining the cleanliness of the surface of polysilicon wafers with the low cleanliness threshold and the high cleanliness threshold; A wastewater recycling module for recycling the clear water after cleaning; A wastewater cleanliness determination module for setting a wastewater cleanliness threshold, comparing the cleanliness of wastewater with the wastewater cleanliness threshold, and selecting a suitable wastewater recycling mode for wastewater.

2. The multi-layer silicon wafer chain single-side chemical cleaning system according to claim 1, characterized in that: The silicon wafer preliminary cleaning module includes: a silicon wafer chain cleaning unit; The silicon wafer chain cleaning unit includes a chain conveyor belt for transporting polysilicon wafers, a cleaning tank for carrying polysilicon wafers, a pure water filling device for injecting pure water into the cleaning tank, a cleaning liquid filling device for injecting cleaning liquid into the cleaning tank, and a clear water filling device for removing the cleaning liquid on the surface of polysilicon wafers; The chain conveyor belt is connected to the cleaning tank, and the pure water filling device, the cleaning liquid filling device, and the clear water filling device are all connected to the cleaning tank; a waste liquid recovery device for storing the used cleaning liquid and a wastewater recovery device for storing the used clear water are provided below the cleaning tank.

3. The multi-layer silicon wafer chain single-side chemical cleaning system according to claim 2, characterized in that: The silicon wafer preliminary cleaning module further includes: a silicon wafer rapid drying unit and a silicon wafer rapid cooling unit; The silicon wafer rapid drying unit is arranged in the subsequent process of the silicon wafer chain cleaning unit, and the silicon wafer rapid cooling unit is arranged in the subsequent process of the silicon wafer rapid drying unit; The silicon wafer rapid drying unit includes a fan heat drying device; The silicon wafer rapid cooling unit includes a condensate refrigeration device.

4. The multi-layer silicon wafer chain single-side chemical cleaning system according to claim 2, characterized in that: Detecting the cleanliness of the surface of polysilicon wafers after preliminary cleaning includes the following steps: Combined with the cleaning batch of polysilicon wafers or a specific time interval, multiple polysilicon wafers are extracted as detection samples, and a CCD vision detector observes the surface of the detection samples and records the quantity, size, and distribution of pollutants on the surface of the detection samples; Calculating the cleanliness of the surface of polysilicon wafers, satisfying the following formula, where CI is the cleanliness index of the surface of polysilicon wafers; N is the quantity of pollutants per unit area on the surface of polysilicon wafers; S is the area of the largest pollutant; D is the average distribution density of pollutants; a and b represent weight coefficients.

5. The multi-layer silicon wafer chain single-side chemical cleaning system according to claim 4, characterized in that: Setting a low cleanliness threshold and a high cleanliness threshold, and comparing the cleanliness of the surface of polysilicon wafers with the low cleanliness threshold and the high cleanliness threshold includes the following steps: Setting a low cleanliness threshold LCT and a high cleanliness threshold HCT, and comparing the cleanliness of the surface of polysilicon wafers with the low cleanliness threshold and the high cleanliness threshold; If CI < LCT, it means that the cleanliness level of the polysilicon wafer is "low"; If LCT ≤ CI < HCT, it means that the cleanliness level of the polysilicon wafer is "medium"; If CI ≥ HCT, it means that the cleanliness level of the polysilicon wafer is "high".

6. The multi-layer silicon wafer chain single-side chemical cleaning system according to claim 5, characterized in that: Selecting a suitable secondary re-washing mode for polysilicon wafers includes the following steps: The cleanliness level of polysilicon wafers is "high", and a simple and low-cost secondary rewashing mode is used: high-pressure cleaning mode; In the high-pressure cleaning mode, high-pressure clean water is used to spray polycrystalline silicon wafers, and pollutants on the surface of the polycrystalline silicon wafers are removed through the impact of fluid dynamics. Antistatic agents need to be added to the high-pressure clean water. The clean water after the polycrystalline silicon wafer cleaning is recovered to the wastewater recovery equipment.

7. The multi-layer silicon wafer chain single-side chemical cleaning system according to claim 5, characterized in that: Selecting the appropriate secondary rewash mode for polysilicon wafers also includes the following steps: For polysilicon wafers with a cleanliness level of "medium", a more sophisticated secondary rewashing mode is used: chemical agent + ultrasonic cleaning mode; In the chemical cleaning mode, an organic solvent is used to clean the surface of the polysilicon wafer for the first time, and an inorganic acid is used to clean the surface of the polysilicon wafer for the second time. Ultrasonic cleaning mode, chemical cleaning mode: The cleaned polysilicon wafers are placed in the cleaning tank of the ultrasonic equipment, and the contaminants on the surface of the polysilicon wafers are removed by ultrasonic vibration.

8. The multi-layer silicon wafer chain single-side chemical cleaning system according to claim 5, characterized in that: Selecting the appropriate secondary rewash mode for polysilicon wafers also includes the following steps: The cleanliness level of polysilicon wafers is "low", so a complex secondary rewashing mode is used: RCA cleaning + ozone microbubble cleaning + vacuum high temperature treatment; The RCA cleaning method uses an ammonia-hydrogen peroxide mixture to clean the surface of the polysilicon wafer for the first time; and uses a hydrochloric acid-hydrogen peroxide mixture to clean the surface of the polysilicon wafer for the second time, completely removing organic matter, metal ions and particulate impurities on the polysilicon surface; Ozone microbubble cleaning, RCA cleaning method After cleaning, the polysilicon wafer uses the high activity and strong oxidizing properties of ozone to remove organic matter and particulate impurities on the surface of the polysilicon wafer. The ozone microbubble cleaning method forms an atomically smooth oxide film on the surface of the polysilicon wafer; Vacuum high temperature treatment, RCA cleaning + ozone microbubble cleaning method After cleaning, the polysilicon wafers are subjected to vacuum high temperature treatment to further remove gases, solvent molecules and solid impurities adsorbed on the surface of the polysilicon wafers.

9. The multi-layer silicon wafer chain single-side chemical cleaning system according to claim 3, characterized in that: The wastewater recycling module includes a water pump power circulation device, a wastewater filtration device and a wastewater detection device; the wastewater filtration device is arranged at the subsequent process of the wastewater recovery device, the wastewater detection device is arranged at the subsequent process of the wastewater filtration device, and the water pump power circulation device is arranged at the subsequent process of the wastewater detection device; Wastewater filtration equipment, used to filter the clean water after cleaning; Wastewater testing equipment, used to test the clean water after filtration; Water pump power circulation equipment is used to input qualified clean water into the clean water filling equipment.

10. The multi-layer silicon wafer chain single-side chemical cleaning system according to claim 9, characterized in that: Wastewater selection of a suitable wastewater circulation mode includes the following steps: Set a wastewater cleanliness threshold, compare the cleanliness of the wastewater with the wastewater cleanliness threshold, and select an appropriate wastewater circulation mode for the wastewater of the wastewater recovery equipment; if the cleanliness of the wastewater is less than the wastewater cleanliness threshold, the clean water is judged to be unqualified, otherwise it is qualified; If the clean water is judged to be qualified in cleanliness, the clean water is input into the clean water filling equipment; if the clean water is judged to be unqualified in cleanliness, the clean water is input into the condensate refrigeration equipment as condensate.

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