Method for removing wafer corrosion stains and liquid medicine residues

Abstract

The invention discloses a method for removing wafer corrosion stains and liquid medicine residues, and particularly relates to the technical field of semiconductor manufacturing, and the method comprises the steps of S1, pre-cleaning treatment, S2, main cleaning sequence, S3, targeted alkali cleaning treatment and S4, deep rinsing and drying. According to the method for removing the wafer corrosion stains and the liquid medicine residues, a dynamic replacement mechanism of gradient HF, laminar flow spraying and automatic liquid replacement with the conductivity larger than 5 microseconds per centimeter is adopted in the main cleaning stage, the batch cleaning consistency is guaranteed, three-step rinsing is matched with rotary spraying in the rinsing and drying link, and the cleaning efficiency is improved. And vacuum drying and a 2-5mm nitrogen cushion layer formed 10 seconds before drying are combined, so that secondary defects such as water marks, oxidation and carbonization are avoided, and the structural integrity of the wafer and the stability of a cleaning process are guaranteed.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing technology, and in particular to a method for removing etching stains and chemical residues from wafers. Background Technology

[0002] In the semiconductor wafer manufacturing process, etching is a core step that uses chemical or physical means to remove excess material from the wafer surface and form fine circuit structures at the micron or even nanometer level.

[0003] Existing cleaning technologies have significant shortcomings: Pre-cleaning lacks a linkage mechanism for real-time detection of dirt types to adapt to megasonic frequencies, resulting in blind cleaning. The main cleaning stage has poor HF concentration adaptability, the spray structure is prone to secondary adsorption of pollutants, and there is no dynamic liquid exchange mechanism to monitor the concentration of impurities in the cleaning solution in real time, resulting in large batch-to-batch fluctuations in performance. KOH alkaline washing for stubborn stains uses a fixed concentration without dynamic concentration compensation, resulting in insufficient cleaning uniformity. In the rinsing and drying process, single-stage rinsing is prone to watermarks, and vacuum or hot air drying can easily lead to secondary defects such as wafer oxidation and organic carbonization. These problems make it difficult to meet the stringent requirements of 7nm and below advanced processes for wafer cleanliness, structural integrity and process consistency.

[0004] Therefore, there is an urgent need for an efficient and precise method to remove wafer etching stains and chemical residues. Summary of the Invention

[0005] The main objective of this invention is to provide a method for removing etching stains and chemical residues from wafers, which can effectively solve the problems mentioned above.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for removing etching stains and chemical residues from wafers includes the following steps: S1: Pre-cleaning treatment; The etched wafers were placed in the SC1 cleaning tank and cleaned with adjustable frequency megasonic waves. At the same time, images of the wafer surface were acquired in real time by an online optical inspection module to determine the density of contaminants and the level of residue. S2: Main cleaning sequence; The pre-cleaned wafers are sequentially passed through the first HF cleaning tank, the TMAH cleaning tank, and the second HF cleaning tank for gradient cleaning. Each tank adopts a laminar flow spray structure and a dynamic displacement mechanism to maintain a solution flow rate of 0.5-0.8 m / s. S3: Targeted alkaline washing treatment; Based on the detection results in S1, potassium hydroxide aqueous solution of the corresponding concentration was injected into the KOH cleaning tank to perform directional alkaline cleaning of the wafer. During the cleaning process, the solution concentration was monitored in real time and dynamically compensated by a pH sensor. S4: Deep rinsing and drying; After alkaline washing, the wafers are placed in an ultrapure water rinsing tank for step-concentration rinsing, and then vacuum drying combined with nitrogen gas cushion layer technology is used to complete the drying process.

[0007] Preferably, in S1, the SC1 cleaning solution is composed of NH4OH, H2O2 and ultrapure water in a mass ratio of 1:1:5-1:2:8, the cleaning temperature is controlled at 65-75℃, and the cleaning time is 8-12 min. The frequency range of the adjustable megasonic wave is 1-3MHz. The frequency is switched according to the type of stain. When metal residue is dominant, 2-3MHz is used, and when organic stain is dominant, 1-2MHz is used.

[0008] Preferably, in step S1, the online optical detection module uses multispectral imaging technology to identify particulate contaminants with a particle size ≥0.1μm and blue liquid residue, and converts the detection results into electrical signals to be transmitted to the process control system.

[0009] Preferably, in step S2, the hydrofluoric acid concentrations in the first HF cleaning tank and the second HF cleaning tank are 0.5-1wt% and 0.1-0.3wt% respectively, the cleaning temperature is 20-25℃, the cleaning time of the first HF is 30-60s, and the cleaning time of the second HF is 15-30s. The TMAH cleaning tank has a tetramethylammonium hydroxide concentration of 2-5 wt%, a temperature of 40-50℃, and a cleaning time of 60-90 seconds.

[0010] Preferably, in S2, the laminar flow spray structure adopts a slit nozzle array to form a parallel liquid film covering the wafer surface, with a Reynolds number Re < 2000; The dynamic replacement mechanism monitors the concentration of impurities in the solution using a conductivity sensor, and automatically triggers the solution replacement procedure when the conductivity exceeds 5 μS / cm.

[0011] Preferably, in step S3, the initial concentration of the KOH aqueous solution is adjusted according to the detection results. When the stain distribution density is ≥5 stains / cm², the concentration is 45-55wt%, and when the stain distribution density is <5 stains / cm², the concentration is 30-40wt%. The cleaning temperature is 75-85℃, and the treatment time is 40-80s.

[0012] Preferably, in step S3, the concentration dynamic compensation adopts a feedforward-feedback composite control, which collects the solution pH value in real time through a pH sensor. When the pH deviates from the target value by ±0.2, concentrated KOH solution or ultrapure water is automatically added, and the compensation response time is ≤2s.

[0013] Preferably, in step S4, the stepped concentration rinsing is divided into three stages: the first stage uses ultrapure water containing 0.01wt% surfactant, the second stage uses ultrapure water with resistivity ≥18MΩ・cm, and the third stage uses ultrapure water sterilized by UV. The rinsing time for each stage is 30-45s, and a rotating spray method is used with a rotation speed of 300-500rpm.

[0014] Preferably, in step S4, the vacuum degree of the vacuum drying is controlled at... Pa, drying temperature is 60-80℃, drying time is 5-8min; The nitrogen gas cushion layer is formed 10 seconds before drying, and the thickness of the cushion layer is 2-5 mm.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention uses an online optical detection module linked to tunable megasonic waves during the pre-cleaning stage to avoid the blindness of fixed-frequency cleaning; combined with the targeted alkaline cleaning stage, the KOH concentration is matched based on the detection data and dynamically compensated in real time by a pH sensor, which can accurately remove different types and densities of corrosion stains and chemical residues, meet the wafer cleanliness requirements of advanced processes at 7nm and below, and avoid damage to the wafer due to improper cleaning parameters.

[0016] 2. The main cleaning stage of this invention adopts a dynamic replacement mechanism of gradient HF, laminar flow spray and automatic liquid replacement with conductivity of over 5μS / cm to ensure batch cleaning consistency. The rinsing and drying stage uses a three-stage rinsing combined with rotating spray, combined with vacuum drying and a 2-5mm nitrogen gas cushion layer formed in the first 10 seconds of drying to eliminate secondary defects such as watermarks, oxidation, and carbonization, and ensure the integrity of the wafer structure and the stability of the cleaning process. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating the overall method of the present invention. Detailed Implementation

[0018] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0019] Example 1, as Figure 1 As shown, a method for removing etching stains and chemical residues from wafers includes the following steps: S1: Pre-cleaning treatment; After the etching process, the wafer with corrosion stains (such as metal oxide particles and organic polymer residues) and chemical residues (such as unreacted etching solution components) on its surface is placed stably in a special cleaning tank containing SC1 cleaning solution. A variable frequency megasonic wave generator is used for auxiliary cleaning. The megasonic wave generates high-frequency vibration energy in the cleaning solution, which can effectively remove tiny contaminants attached to the wafer surface and avoid damage to the wafer substrate. Meanwhile, the online optical inspection module integrated in the cleaning tank captures image information of every area on the wafer surface in real time through a high-definition image acquisition unit. The acquired image data is transmitted to the background analysis system. The system uses image recognition algorithms to calculate the distribution density (number of stains per unit area) and residual level (divided into low, medium, and high levels based on the stain coverage area and residual thickness), and feeds the results back to the process control terminal in real time, providing accurate data support for subsequent targeted treatment.

[0020] S2: Main cleaning sequence; After pre-cleaning, the wafers, whose surfaces have been largely free of easily removable contaminants, are sequentially fed into the first HF cleaning tank, the TMAH cleaning tank, and the second HF cleaning tank according to a preset transport path for gradient cleaning. This gradient cleaning method achieves the step-by-step removal of contaminants of different properties through the sequential action of different types of cleaning solutions. Each cleaning tank adopts a laminar flow spray structure. This structure uses a precisely designed fluid channel to make the cleaning fluid flow in a stable laminar flow state. At the same time, it is combined with a slit nozzle array to evenly spray the cleaning fluid to form a continuous parallel liquid film. The liquid film completely covers every area of ​​the wafer surface, ensuring that there are no dead corners in the cleaning. The laminar flow state can also prevent the cleaning fluid from generating eddies that could cause secondary adhesion of contaminants. Meanwhile, each tank is equipped with a dynamic replacement mechanism to maintain the purity and activity of the cleaning solution in real time; During the cleaning process, the flow rate of the cleaning solution is strictly controlled at 0.5-0.8 m / s. This flow rate ensures that the cleaning solution is in full contact with the wafer surface and quickly removes reaction products and contaminants, while also preventing the cleaning solution from splashing or exerting excessive impact on the wafer due to excessive flow rate, which could affect the wafer's positional stability.

[0021] S3: Targeted alkaline washing treatment; Based on the data on dirt distribution density and residue level obtained by the online optical detection module in S1, the process control system automatically calculates and determines the appropriate concentration of potassium hydroxide (KOH) aqueous solution, and then injects the corresponding concentration of KOH aqueous solution into the KOH cleaning tank through a precision metering pump. Wafers that still have specific contaminants (such as highly adhesive metal compounds and stubborn organic residues) after the main cleaning sequence are sent to a KOH cleaning tank for targeted alkaline cleaning. KOH, as a strong alkaline solution, can react chemically with such stubborn contaminants, destroy the structural stability of the contaminants, and transform them into soluble substances, thereby achieving targeted removal. During the cleaning process, the pH sensor integrated in the KOH cleaning tank collects the pH value of the cleaning solution in real time (the pH value directly reflects the KOH concentration) and transmits the pH data to the concentration control unit in real time. When the concentration of the cleaning solution changes due to reaction consumption or water evaporation, the control unit promptly activates the dynamic compensation mechanism to ensure that the concentration of the cleaning solution is always maintained within the target range, thus ensuring the stability of the targeted alkaline cleaning effect.

[0022] S4: Deep rinsing and drying; Wafers that may have residual KOH solution and reaction products on their surface after targeted alkaline washing are transferred to an ultrapure water rinsing tank for step-by-step concentration rinsing. Step-by-step rinsing avoids watermarks or re-adsorption of impurities on the wafer surface due to excessive concentration difference by gradually reducing the concentration of impurities in the cleaning solution. After rinsing, the wafers are sent to a vacuum drying equipment. A composite drying technology combining vacuum drying with a nitrogen gas cushion layer is used. The vacuum environment can quickly lower the boiling point of water and accelerate the evaporation of moisture on the wafer surface. At the same time, the nitrogen gas cushion layer can form an inert gas protective film on the wafer surface to prevent the wafer surface from reacting with oxygen and carbon dioxide in the air during the drying process, which could lead to oxidation or contamination. Ultimately, this achieves rapid and non-damaging drying of the wafer surface.

[0023] In Example 2, further, in S1, the SC1 cleaning solution is prepared by mixing NH4OH (ammonium hydroxide), H2O2 (hydrogen peroxide) and ultrapure water in a specific ratio. NH4OH can adjust the pH value of the cleaning solution to an alkaline environment, promoting the decomposition and dissolution of organic stains. H2O2, as an oxidant, can oxidize and remove metal residues on the wafer surface (such as Cu, Fe, Ni metal ions, which are converted into soluble oxides). Ultrapure water, as a solvent, ensures the purity of the cleaning solution and avoids the introduction of new impurities. The mass ratio of the three components is controlled within the range of 1:1:5-1:2:8, which can ensure the cleaning effect while avoiding excessive corrosion of the wafer surface. The cleaning temperature is set at 65-75℃. This temperature range can significantly enhance the activity of each component in the cleaning solution, accelerate the reaction rate between dirt and chemical residue, and at the same time avoid excessive temperature from causing oxidation of the wafer surface or decomposition of the cleaning solution components. The cleaning time is controlled at 8-12 minutes to ensure that surface contaminants are fully removed and to prevent prolonged cleaning from adversely affecting the wafer surface morphology.

[0024] The frequency range of the tunable megasonic wave is set to 1-3MHz. The megasonic wave energy in this frequency range is moderate, which can effectively act on contaminants on the wafer surface without causing excessive cavitation effect that damages the wafer. When the wafer surface is dominated by metal residues (such as metal particles and metal ion complexes), a higher frequency of 2-3MHz is used. The higher frequency megasonic vibration can act more precisely on the hard metal contaminants and promote their removal from the wafer surface. When organic contaminants (such as photoresist residue and polymer decomposition products) are the dominant pollutants, a lower frequency of 1-2MHz is used. The lower frequency megasonic waves can form a wider vibration field in the cleaning solution, which is more conducive to the decomposition and stripping of organic flexible contaminants.

[0025] Furthermore, in S1, the online optical inspection module employs multispectral imaging technology. This technology illuminates the wafer surface by emitting probe light of different wavelengths (such as visible light and near-infrared light). Different types of contaminants (particulate stains, chemical residues) exhibit different reflection and absorption characteristics to different wavelengths of light. By acquiring multi-band optical signals and performing comparative analysis, the module can accurately identify micro-particle stains with a particle size ≥0.1μm (this particle size is a critical contaminant control threshold in semiconductor wafer manufacturing; particles smaller than this size have little impact on subsequent processes, while particles larger may lead to device failure). At the same time, it can accurately distinguish chemical residues with a characteristic blue color (such as blue compound residues generated after some etching solution reacts with the wafer). After the detection is completed, the module converts the identified dirt location, quantity, residue type and other information into a standard electrical signal through the signal conversion unit and transmits it to the wafer cleaning process control system. The system adjusts the subsequent cleaning parameters in real time according to the electrical signal to realize closed-loop control of the cleaning process.

[0026] Furthermore, in S2, the concentration of hydrofluoric acid (HF) in the first HF cleaning tank is set to 0.5-1wt%. This concentration of HF can quickly react chemically with the oxide layer (such as SiO2 oxide layer) and attached metal oxide contaminants on the wafer surface to generate soluble fluorides, thereby removing such contaminants. The cleaning temperature is controlled at 20-25℃ (room temperature range) to avoid excessive corrosion of HF at high temperatures that could damage the wafer. The cleaning time is set to 30-60s to ensure that thicker oxide layers and stubborn metal oxides are fully removed. The hydrofluoric acid concentration in the second HF cleaning tank is reduced to 0.1-0.3 wt%. The purpose of using low-concentration HF for secondary cleaning is to remove any residual fluoride products and trace amounts of unreacted oxide layer that may have remained after the first HF cleaning, while reducing excessive corrosion of the wafer surface and protecting the fine structure of the wafer surface. The cleaning temperature is also maintained at 20-25℃, and the cleaning time is shortened to 15-30 seconds, which improves process efficiency while ensuring the cleaning effect.

[0027] The concentration of tetramethylammonium hydroxide (TMAH) in the TMAH cleaning tank is 2-5 wt%. As a weakly alkaline cleaning solution, TMAH can effectively dissolve organic contaminants (such as residual photoresist components and organic polymers) on the wafer surface. At the same time, it has a certain chelating effect on metal ions on the wafer surface. The cleaning temperature is set at 40-50℃, which can increase the dissolution rate of TMAH on organic contaminants and accelerate the cleaning process. The cleaning time is controlled at 60-90 seconds to ensure that the organic contaminants are completely dissolved and carried away by the cleaning solution.

[0028] Furthermore, in S2, the laminar flow spray structure adopts a precision-machined slit nozzle array. The slit width of the nozzle is controlled at 0.1-0.3mm to ensure that the cleaning fluid forms a parallel liquid film of uniform thickness (0.5-1mm) when it is sprayed from the nozzle. This liquid film can cover the wafer surface in a stable laminar flow state, avoiding turbulence that would cause contaminants to be stirred up and re-adhere to the wafer surface. Through fluid dynamics calculations and adjustments, the Reynolds number (Re) in the laminar flow spraying process is controlled to be less than 2000. A Reynolds number Re < 2000 is a key indicator for determining the laminar flow state. Under this state, the cleaning fluid flows smoothly, has high mass transfer efficiency, and can efficiently remove contaminants and reaction products from the wafer surface. The dynamic displacement mechanism monitors the concentration of impurities in the cleaning solution in real time using a high-precision conductivity sensor. During the cleaning process, as contaminants dissolve and reaction products are generated, the conductivity of the cleaning solution gradually increases (pure cleaning solution has extremely low conductivity, while the increase in impurity ions leads to an increase in conductivity). When the conductivity sensor detects that the conductivity of the cleaning fluid exceeds 5 μS / cm, it indicates that the impurity content in the cleaning fluid has reached the threshold that affects the cleaning effect. At this time, the system automatically triggers the fluid replacement program, injecting new pure cleaning fluid through the inlet valve and discharging old cleaning fluid containing a large amount of impurities through the drain valve, thereby realizing the dynamic renewal of the cleaning fluid and always maintaining the high purity and high decontamination ability of the cleaning fluid.

[0029] Furthermore, in S3, the initial concentration of the KOH aqueous solution is strictly adjusted according to the stain distribution density obtained from S1. When the test results show that the stain distribution density on the wafer surface is ≥5 stains / cm², it indicates that the wafer surface is heavily contaminated and a higher concentration (45-55wt%) of KOH aqueous solution is required. A higher concentration of KOH can provide stronger chemical reactivity and quickly decompose high-density stubborn stains. When the density of contaminants is less than 5 per cm², the surface contamination of the wafer is relatively mild. A low concentration (30-40 wt%) of KOH aqueous solution can effectively remove residual contaminants while avoiding excessive corrosion of the wafer surface by high concentrations of KOH.

[0030] The cleaning temperature is controlled at 75-85℃. This temperature range can significantly accelerate the reaction rate of KOH with stubborn stains, shorten the cleaning time, and at the same time avoid excessive temperature from causing the KOH solution to evaporate too quickly or causing oxidation and discoloration on the wafer surface. The processing time is set to 40-80 seconds, with the specific time dynamically adjusted according to the level of dirt residue (80 seconds for high residue level and 40 seconds for low residue level) to ensure that dirt is thoroughly removed while preventing adverse effects on the electrical properties and surface morphology of the wafer from prolonged high temperature and strong alkaline environment.

[0031] Furthermore, in S3, the concentration dynamic compensation adopts a feedforward-feedback composite control strategy. The feedforward control unit calculates the theoretical consumption of KOH during the cleaning process in advance based on the preset process parameters such as the total amount of dirt detected by S1 and the cleaning time, and replenishes an appropriate amount of concentrated KOH solution or ultrapure water into the cleaning tank in advance to achieve early intervention on concentration changes. Meanwhile, the feedback control unit collects the actual pH value of the cleaning solution in real time through the pH sensor and compares it with the target pH value (determined according to the set KOH concentration). When the pH value deviates from the target value by ±0.2 units, it indicates that the concentration of the cleaning solution has exceeded the allowable error range. At this time, the feedback control unit immediately issues a command to automatically replenish concentrated KOH solution (when the pH is lower than the target value, i.e., the concentration is insufficient) or ultrapure water (when the pH is higher than the target value, i.e., the concentration is too high) through the high-precision dosing pump. The response time of the entire compensation system is controlled within ≤2s, which can quickly correct the deviation of the cleaning solution concentration, avoid the decrease in cleaning effect or wafer damage caused by concentration fluctuations, and ensure the stability and consistency of the targeted alkaline washing process.

[0032] Furthermore, in S4, the stepped concentration rinsing is divided into three consecutive cleaning stages, each stage achieving a different cleaning objective in turn: The first stage of rinsing uses ultrapure water containing 0.01 wt% nonionic surfactant. The surfactant can reduce the surface tension of ultrapure water, enhance the ability to penetrate and remove residual impurities in the tiny gaps on the wafer surface, and at the same time prevent impurity particles from agglomerating on the wafer surface during the rinsing process. The second-stage rinsing uses high-purity ultrapure water with a resistivity ≥18MΩ・cm (this resistivity is the standard indicator for electronic-grade ultrapure water, indicating that the water contains almost no ionic impurities). The high-purity ultrapure water rinsing thoroughly removes any surfactants and other soluble impurities that may remain after the first-stage rinsing. The third-stage rinsing uses ultrapure water that has been treated with UV (ultraviolet light) sterilization. UV sterilization can effectively kill microorganisms (such as bacteria and fungi) that may exist in ultrapure water, preventing microorganisms from adhering to the wafer surface and causing contamination in subsequent processes.

[0033] The rinsing time for each stage is controlled at 30-45 seconds to ensure thorough rinsing while improving process efficiency. The rinsing process uses a rotating spray method. The wafer is fixed on the rotating platform by a special clamp, and the rotation speed is set to 300-500 rpm. The centrifugal force generated by the rotation can accelerate the removal of water after rinsing, and at the same time, the sprayed ultrapure water can evenly cover both sides of the wafer to avoid rinsing dead corners.

[0034] Furthermore, in S4, during the vacuum drying process, the vacuum level inside the vacuum drying equipment is strictly controlled at... The high vacuum range of Pa can significantly reduce the saturated vapor pressure of moisture, allowing moisture on the wafer surface to evaporate quickly at a lower temperature, thus avoiding damage to the fine structure of the wafer surface caused by high-temperature drying. The drying temperature is set at 60-80℃. This temperature can further accelerate the evaporation rate of moisture, and is far below the heat resistance threshold of wafer materials and surface coatings, preventing thermal deformation or performance degradation of the wafer. The drying time is controlled at 5-8 minutes, and dynamically adjusted according to the amount of residual moisture on the wafer surface (8 minutes if there is a lot of residual moisture, 5 minutes if there is a little) to ensure that the moisture on the wafer surface is completely evaporated and the drying standard is met.

[0035] The formation of the nitrogen gas cushion layer is precisely controlled 10 seconds before the start of vacuum drying. At this time, the wafer has entered the drying chamber and the chamber has begun to be evacuated. High-purity nitrogen (purity ≥99.999%) is introduced in advance to make the nitrogen evenly distributed on the wafer surface and form a gas cushion layer with a thickness of 2-5mm. This thickness of air cushion layer can effectively isolate the wafer surface from any residual oxygen and moisture in the cavity, preventing oxidation and secondary contamination, while not hindering the subsequent evaporation of moisture in the vacuum environment, thus achieving the dual goals of drying effect and surface protection.

[0036] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for removing etching stains and chemical residues from wafers, characterized in that, Includes the following steps: S1: Pre-cleaning treatment; The etched wafers were placed in the SC1 cleaning tank and cleaned with adjustable frequency megasonic waves. At the same time, images of the wafer surface were acquired in real time by an online optical inspection module to determine the density of contaminants and the level of residue. S2: Main cleaning sequence; The pre-cleaned wafers are sequentially passed through the first HF cleaning tank, the TMAH cleaning tank, and the second HF cleaning tank for gradient cleaning. Each tank adopts a laminar flow spray structure and a dynamic displacement mechanism to maintain a solution flow rate of 0.5-0.8 m / s. S3: Targeted alkaline washing treatment; Based on the detection results in S1, potassium hydroxide aqueous solution of the corresponding concentration was injected into the KOH cleaning tank to perform directional alkaline cleaning of the wafer. During the cleaning process, the solution concentration was monitored in real time and dynamically compensated by a pH sensor. S4: Deep rinsing and drying; After alkaline washing, the wafers are placed in an ultrapure water rinsing tank for step-concentration rinsing, and then vacuum drying combined with nitrogen gas cushion layer technology is used to complete the drying process.

2. The method for removing etching stains and chemical residues from wafers according to claim 1, characterized in that: In S1, the SC1 cleaning solution is composed of NH4OH, H2O2 and ultrapure water in a mass ratio of 1:1:5-1:2:8, the cleaning temperature is controlled at 65-75℃, and the cleaning time is 8-12min. The frequency range of the adjustable megasonic wave is 1-3MHz. The frequency is switched according to the type of stain. When metal residue is dominant, 2-3MHz is used, and when organic stain is dominant, 1-2MHz is used.

3. The method for removing etching stains and chemical residues from wafers according to claim 1, characterized in that: In S1, the online optical detection module uses multispectral imaging technology to identify particulate contaminants with a particle size ≥0.1μm and blue liquid residue, and converts the detection results into electrical signals to be transmitted to the process control system.

4. The method for removing etching stains and chemical residues from wafers according to claim 1, characterized in that: In step S2, the hydrofluoric acid concentrations in the first HF cleaning tank and the second HF cleaning tank are 0.5-1wt% and 0.1-0.3wt% respectively, the cleaning temperature is 20-25℃, the cleaning time of the first HF is 30-60s, and the cleaning time of the second HF is 15-30s. The TMAH cleaning tank has a tetramethylammonium hydroxide concentration of 2-5 wt%, a temperature of 40-50℃, and a cleaning time of 60-90 seconds.

5. The method for removing etching stains and chemical residues from wafers according to claim 1, characterized in that: In S2, the laminar flow spray structure adopts a slit nozzle array to form a parallel liquid film covering the wafer surface, with a Reynolds number Re < 2000; The dynamic replacement mechanism monitors the concentration of impurities in the solution using a conductivity sensor, and automatically triggers the solution replacement procedure when the conductivity exceeds 5 μS / cm.

6. The method for removing etching stains and chemical residues from wafers according to claim 1, characterized in that: In step S3, the initial concentration of the KOH aqueous solution is adjusted according to the detection results. When the stain distribution density is ≥5 stains / cm², the concentration is 45-55wt%, and when the stain distribution density is <5 stains / cm², the concentration is 30-40wt%. The cleaning temperature is 75-85℃, and the treatment time is 40-80s.

7. The method for removing etching stains and chemical residues from wafers according to claim 1, characterized in that: In S3, the concentration dynamic compensation adopts a feedforward-feedback composite control. The pH value of the solution is collected in real time by a pH sensor. When the pH deviates from the target value by ±0.2, concentrated KOH solution or ultrapure water is automatically added, and the compensation response time is ≤2s.

8. The method for removing etching stains and chemical residues from wafers according to claim 1, characterized in that: In S4, the stepped concentration rinsing is divided into 3 stages. The first stage uses ultrapure water containing 0.01wt% surfactant, the second stage uses ultrapure water with resistivity ≥18MΩ・cm, and the third stage uses ultrapure water sterilized by UV. The rinsing time for each stage is 30-45s, and a rotating spray method is used with a rotation speed of 300-500rpm.

9. The method for removing etching stains and chemical residues from wafers according to claim 1, characterized in that: In step S4, the vacuum degree of the vacuum drying is controlled at... Pa, drying temperature is 60-80℃, drying time is 5-8min; The nitrogen gas cushion layer is formed 10 seconds before drying, and the thickness of the cushion layer is 2-5 mm.

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