Wafer cleaning and drying method and device

Abstract

The invention provides a wafer cleaning and drying method and device, and belongs to the technical field of semiconductor manufacturing. The method comprises the following steps: immersing a wafer in a cleaning solution for a preset time; lifting the wafer at a first speed; continuously lifting the wafer upwards at a second speed, wherein the second speed is a lifting speed dynamically determined according to a real-time measurement result of the liquid film on the surface of the wafer; and continuously lifting the wafer upwards at a first speed until the wafer reaches a preset position. In the soaking stage, the cleaning liquid fully permeates the surface of the wafer and micro-nano defects; local residues caused by uneven initial liquid film in the subsequent stage are reduced in the initial extraction stage; the residual risk caused by uneven rupture of a liquid film is reduced in the intermediate extraction stage; and in the final pulling stage, natural fracture of the liquid film on a gas-liquid interface is realized, water mark formation and secondary adsorption of particles carried by residual liquid are reduced, and the cleanliness of the wafer is improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing technology, and in particular to a method and apparatus for cleaning and drying wafers. Background Technology

[0002] In semiconductor wafer manufacturing, cleaning and drying are crucial steps to ensure the cleanliness of the wafer surface. Generally, low-flow drying (LFD) is used to control the pulling speed, so that gravity and the adhesion of water on the wafer surface are balanced, allowing the water to flow down naturally under the action of gravity.

[0003] However, different cleaning solutions have different surface tensions, and different wafers also have different surface roughnesses. Affected by factors such as surface tension and wafer roughness, the solution film rupture process during drying is inconsistent, and some areas of the solution fail to detach in time, forming residues that affect subsequent processes; furthermore, the dehydration rate at the wafer edge and center differs to varying degrees, and residual moisture may carry particulate impurities, causing secondary adsorption and affecting the cleanliness of the wafer. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a method and apparatus for cleaning and drying wafers, which can improve the cleanliness of wafers.

[0005] To achieve the above objectives, the technical solution adopted in the embodiments of the present invention is as follows:

[0006] This invention provides a method for cleaning and drying wafers, the method comprising:

[0007] Immerse the wafer in the cleaning solution for a preset time;

[0008] Pull the wafer upwards at a first speed until the upper edge of the wafer is on the same plane as the surface of the cleaning solution;

[0009] The wafer is pulled upward at a second speed until the lower edge of the wafer separates from the surface of the cleaning solution. The second speed is a pulling speed dynamically determined based on real-time measurement results of the liquid film on the wafer surface.

[0010] Continue to pull the wafer upward at the first speed until the wafer reaches the preset position.

[0011] In some embodiments, the step of continuing to pull the wafer upward at a second speed until the lower edge of the wafer separates from the surface of the cleaning solution includes:

[0012] The wafer is pulled upwards at the first target speed, and the thickness of the liquid film on the surface of the wafer is measured in real time using a laser interferometer to obtain the real-time measurement result.

[0013] If the real-time measurement results indicate that the difference between the thickness of the liquid film on the surface of the wafer edge region and the thickness of the liquid film on the surface of the wafer center region is greater than a preset threshold, the first target speed is positively compensated to obtain a second target speed, wherein the second target speed is greater than the first target speed.

[0014] If the real-time measurement results indicate that the difference between the thickness of the liquid film on the surface of the wafer edge region and the thickness of the liquid film on the surface of the wafer center region is less than or equal to the preset threshold, the first target speed is reverse-compensated to obtain a third target speed, wherein the third target speed is less than the first target speed.

[0015] The wafer is pulled upward at a second speed until the lower edge of the wafer is separated from the surface of the cleaning solution. The second speed includes the first target speed, the second target speed, and the third target speed.

[0016] In some embodiments, the step of pulling the wafer upward at a first speed until the upper edge of the wafer is on the same plane as the surface of the cleaning solution includes:

[0017] The wafer is pulled upward at a first speed, and the first transducer is controlled to work alternately at a first ultrasonic frequency and a second ultrasonic frequency until the upper edge of the wafer contacts the surface of the cleaning fluid, wherein the second ultrasonic frequency is greater than the first ultrasonic frequency.

[0018] In some embodiments, the first ultrasonic frequency is 28 kHz to 30 kHz, and the second ultrasonic frequency is 40 kHz to 45 kHz.

[0019] In some embodiments, the step of continuing to pull the wafer upward at a second speed until the lower edge of the wafer separates from the surface of the cleaning solution includes:

[0020] The wafer is pulled upward at a second speed, and the second transducer is controlled to operate at a third ultrasonic frequency until the lower edge of the wafer is separated from the surface of the cleaning solution.

[0021] In some embodiments, the third ultrasonic frequency is 1 MHz to 1.3 MHz.

[0022] In some embodiments, when the wafer is immersed in the cleaning solution, the temperature of the cleaning solution is controlled at a first temperature;

[0023] When the wafer is pulled upward at a first speed, the temperature of the cleaning solution is controlled at a second temperature.

[0024] While the wafer continues to be pulled upward at the second speed, the temperature of the cleaning solution is controlled at the second temperature, which is dynamically determined based on the second speed and is greater than the first temperature.

[0025] In some embodiments, the first temperature is 25°C to 26°C, and the second temperature is 35°C to 40°C.

[0026] In some embodiments, the first velocity is in the range of 0 mm / s to 0.4 mm / s, and the second velocity is in the range of 0.5 mm / s to 2 mm / s.

[0027] This invention also provides a wafer cleaning and drying apparatus, the apparatus comprising:

[0028] A cleaning tank filled with cleaning fluid;

[0029] Lifting structure;

[0030] The workpiece holder connected to the lifting structure is used to carry the wafer;

[0031] A laser interferometer is disposed at the opening of the cleaning tank and configured to measure the thickness of the liquid film on the surface of the wafer in real time during the process of the lifting structure lifting the workpiece holder so that the workpiece holder carries the wafer and floats out of the liquid surface of the cleaning solution.

[0032] A speed compensation module is electrically connected to the laser interferometer to obtain the real-time measurement results of the laser interferometer and determine the speed at which the lifting structure lifts the workpiece frame upward based on the real-time measurement results.

[0033] The beneficial effects of this invention are:

[0034] In this embodiment, during the immersion stage, the cleaning solution fully penetrates the wafer surface and micro-nano defects through a preset immersion time, using liquid swelling to peel off large-particle contaminants and loosen micro-nano-level impurities. During the initial lifting stage, the wafer is lifted at a first speed to drive the liquid film to flow towards the edge, reducing local residues caused by uneven initial liquid film in subsequent stages. During the intermediate lifting stage, a second speed is dynamically determined based on real-time measurements of the liquid film on the wafer surface to balance gravity and adhesion, reducing the risk of residues caused by uneven liquid film rupture. This can adapt to differences in surface tension of different cleaning solutions and differences in surface roughness of different wafers. During the final lifting stage, the wafer continues to be lifted upwards at a first speed, achieving natural rupture of the liquid film at the gas-liquid interface, reducing watermark formation and secondary adsorption of particles carried by residual liquid, and improving the cleanliness of the wafer. Attached Figure Description

[0035] Figure 1 A schematic flowchart illustrating the wafer cleaning and drying method in an embodiment of the present invention;

[0036] Figure 2 A schematic diagram showing the structure of the wafer cleaning and drying apparatus in an embodiment of the present invention;

[0037] Figure 3 This is a schematic diagram of the structure of the electronic device in an embodiment of the present invention. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0039] Different cleaning solutions have varying surface tensions, and different wafers also have varying surface roughness. Due to factors such as surface tension and wafer roughness, the solution film rupture process during drying is inconsistent, and some areas of the solution fail to detach in time, leaving residues that affect subsequent processes. Furthermore, the dehydration rate differs to varying degrees between the wafer edge and the center, and residual moisture may carry particulate impurities, causing secondary adsorption and affecting the cleanliness of the wafer.

[0040] This invention provides a method and apparatus for cleaning and drying wafers, which can improve the cleanliness of wafers.

[0041] This invention provides a method for cleaning and drying wafers, such as... Figure 1 As shown, it includes:

[0042] Step 101: Immerse the wafer in the cleaning solution for a preset time.

[0043] This step is the immersion stage, in which the wafer is immersed in the cleaning solution of the cleaning machine, so that the contaminants on the wafer surface are loosened by the immersion action of the cleaning solution. During this stage, the immersion time is preset, such as 30s to 120s of stillness time under the liquid surface, in order to remove large particles of contaminants from the surface.

[0044] Step 102: Pull the wafer upward at a first speed until the upper edge of the wafer is on the same plane as the surface of the cleaning solution.

[0045] This step is the initial lifting stage. After the soaking stage, the wafer is lifted until the upper edge of the wafer is on the same plane as the surface of the cleaning solution. In other words, during the initial lifting stage, the wafer is completely below the liquid surface. When lifting the wafer upward at the first speed, the first speed can be a uniform motion, so that the liquid film on the wafer surface flows uniformly towards the lower edge of the wafer, which facilitates the rapid separation of the liquid film from the wafer in the subsequent process.

[0046] In the initial lifting stage, the wafer is completely below the liquid surface. During the upward lifting process, the position on the wafer's circumference that first contacts the liquid surface is the upper edge of the wafer. When the upper edge of the wafer is on the same plane as the liquid surface, that is, when the upper edge of the wafer contacts the liquid surface, the initial lifting stage ends, and the wafer is still below the liquid surface.

[0047] The bottom edge of a wafer is opposite the top edge, and the distance between the bottom edge and the top edge is the diameter of the wafer.

[0048] Step 103: Continue to pull the wafer upward at the second speed until the lower edge of the wafer separates from the surface of the cleaning solution. The second speed is a pulling speed dynamically determined based on the real-time measurement results of the liquid film on the wafer surface.

[0049] This step is the intermediate lifting stage. After the initial lifting stage, the wafer is further pulled until its lower edge separates from the surface of the cleaning solution. During the intermediate lifting stage, part of the wafer is above the liquid surface, while the other part remains below. The point where the wafer's circumference finally contacts the cleaning solution surface during this upward pulling process is the lower edge of the wafer. The intermediate lifting stage ends when the lower edge of the wafer separates from the cleaning solution surface, at which point the wafer is above the liquid surface.

[0050] During the intermediate lifting stage, the thickness of the liquid film on the wafer surface can be measured in real time using a laser interferometer (0.1 nm resolution). The lifting speed is dynamically determined based on the measurement results, ensuring a dynamic balance between gravity and adhesion of the liquid film during the lifting stage. For example, when the liquid film is locally too thick (adhesion dominates), the speed is automatically reduced to prolong the time of gravity action, avoiding uneven cracking and residue caused by insufficient tension. When the liquid film thins to a critical state (gravity dominates), the speed is appropriately increased to improve production efficiency while ensuring drying quality. Furthermore, for high surface tension solutions (such as alkaline solutions containing surfactants), the lifting speed can be automatically reduced to ensure sufficient time for gravity to overcome strong adhesion; for low surface tension solutions (such as diluted HF solutions), the lifting speed can be automatically increased to shorten the process time without affecting the drying effect.

[0051] Furthermore, at this stage, it is considered that some areas of the wafer are directly exposed to the air interface, resulting in abnormal dehydration rates due to fluid disturbances (such as edge eddies and liquid surface fluctuations). Dynamically adjusting the pull-up speed can eliminate the difference in dehydration rates between the wafer edge and center. For example, when the liquid film thickness at the edge is lower than the critical value in the center region, the pull-up speed in the corresponding edge region is automatically reduced to slow down the dehydration rate. By dynamically determining the pull-up speed based on real-time measurement results, the difference in liquid film thickness decay rates between the edge and center is reduced to within 5%, thus preventing edge residue and center droplet aggregation caused by uneven dehydration from the source.

[0052] Step 104: Continue to pull the wafer upward at the first speed until the wafer reaches the preset position.

[0053] This step is the final pulling stage. After the intermediate pulling stage, the wafer is further pulled until it reaches the preset position. During the final pulling stage, the wafer is completely above the liquid surface. When pulling the wafer upward at the first speed, the first speed can be a constant speed, allowing the residual liquid film on the wafer surface to naturally break at the gas-liquid interface (fracture energy < 0.1 J / m). 2 Natural cooling eliminates thermal stress (cooling rate ≤ 0.5℃ / s) and prevents watermarks from remaining.

[0054] In this embodiment of the invention, during the immersion stage, the cleaning solution fully penetrates the wafer surface and micro-nano defects through a preset immersion time, using liquid swelling to peel off large particulate contaminants and loosen micro-nano-level impurities. During the initial lifting stage, the wafer is lifted at a first speed to drive the liquid film to flow towards the edge, reducing local residues caused by uneven initial liquid film in subsequent stages. During the intermediate lifting stage, a second speed is dynamically determined based on real-time measurements of the liquid film on the wafer surface to balance gravity and adhesion, reducing the risk of residues caused by uneven liquid film rupture. This can adapt to differences in surface tension of different cleaning solutions and differences in surface roughness of different wafers. During the final lifting stage, the wafer continues to be lifted upwards at a first speed, achieving natural rupture of the liquid film at the gas-liquid interface, reducing watermark formation and secondary adsorption of particles carried by residual liquid, and improving the cleanliness of the wafer.

[0055] In some embodiments, the step of continuing to pull the wafer upward at a second speed until the lower edge of the wafer separates from the surface of the cleaning solution includes:

[0056] The wafer is pulled upwards at the first target speed, and the thickness of the liquid film on the surface of the wafer is measured in real time using a laser interferometer to obtain the real-time measurement result.

[0057] If the real-time measurement results indicate that the difference between the thickness of the liquid film on the surface of the wafer edge region and the thickness of the liquid film on the surface of the wafer center region is greater than a preset threshold, the first target speed is positively compensated to obtain a second target speed, wherein the second target speed is greater than the first target speed.

[0058] If the real-time measurement results indicate that the difference between the thickness of the liquid film on the surface of the wafer edge region and the thickness of the liquid film on the surface of the wafer center region is less than or equal to the preset threshold, the first target speed is reverse-compensated to obtain a third target speed, wherein the third target speed is less than the first target speed.

[0059] The wafer is pulled upward at a second speed until the lower edge of the wafer is separated from the surface of the cleaning solution. The second speed includes the first target speed, the second target speed, and the third target speed.

[0060] In this embodiment, the thickness of the liquid film on the wafer surface can be measured in real time using a laser interferometer. The liquid film thickness data of the edge and center regions can be obtained and the difference can be compared. When the difference between the two exceeds a preset threshold (e.g., 10%), the system dynamically compensates the lifting speed based on the real-time measurement results to determine the second speed.

[0061] Specifically, during the lifting stage, the wafer is first lifted upwards at a first target speed, and the thickness of the liquid film on the wafer's surface is measured in real time using a laser interferometer to obtain real-time measurement results. The first target speed can be a preset base lifting speed. After a period of upward lifting, part of the wafer is above the liquid surface, while the other part remains below. Considering the environmental differences when measuring the thickness of the liquid film on the wafer's surface, environmental differences can be eliminated by combining dual-mode interferometry with refractive index compensation to ensure data comparability. For example, for the part above the liquid surface, the displacement of the interference fringes due to the refractive index difference Δn = 0.33 at the air-liquid film interface can be directly detected to measure the thickness h1 of the liquid film on the wafer above the liquid surface; for the part below the liquid surface, a refractive index compensation algorithm can be used to measure the thickness h2 of the liquid film on the wafer below the liquid surface, where the corresponding intermediate laser wavelength is corrected to λ based on the refractive index of the cleaning fluid (refractive index 1.33). eff =λ0 / n 液 , λ eff The corrected wavelength is λ0, the initial wavelength is n. 液 Let be the refractive index of the cleaning fluid. When calculating the thickness difference, the portion above and below the liquid surface at the radial position of the wafer is normalized using the following formula:

[0062]

[0063] After obtaining the thickness difference Δh through the above steps, it is compared with a preset threshold, which can be 10%.

[0064] In one example, if Δh is greater than 10%, then the first target velocity is positively compensated to obtain the second target velocity: v2=v1+Kp·(Δh-10%)+Ki∫(Δh-10%)dt; where v2 is the second target velocity, v1 is the first target velocity, Kp is the proportional coefficient, and Ki is the integral coefficient.

[0065] In another example, if Δh is less than or equal to 10%, the first target velocity is compensated in reverse to obtain the third target velocity: v3 = v1 * 0.8; where v3 is the third target velocity.

[0066] The second speed includes v1, v2 and v3.

[0067] In this way, by precisely capturing the unevenness of the liquid film thickness between the edge and the center, the local lifting speed can be adjusted accordingly. For example, if the liquid film at the edge is too thin, the lifting speed in the corresponding area can be reduced to slow down dehydration; if the liquid film at the center is too thick, the speed can be appropriately increased to enhance the gravity peeling effect. This balances the dehydration rate between the edge and the center, avoiding uneven breakage, solution residue, and secondary adsorption of particles with residual liquid caused by differences in liquid film thickness, ensuring that the liquid film thins uniformly during the lifting process. This achieves natural breakage of the liquid film at the gas-liquid interface, reducing watermark formation and secondary adsorption of particles carried by residual liquid, thus improving the cleanliness of the wafer.

[0068] In some embodiments, the step of pulling the wafer upward at a first speed until the upper edge of the wafer is on the same plane as the surface of the cleaning solution includes:

[0069] The wafer is pulled upward at a first speed, and the first transducer installed in the cleaning machine is controlled to work alternately at a first ultrasonic frequency and a second ultrasonic frequency until the upper edge of the wafer contacts the surface of the cleaning liquid, wherein the second ultrasonic frequency is greater than the first ultrasonic frequency.

[0070] In this embodiment, during the initial lifting stage, while the system lifts the wafer at a uniform speed at a first speed, it controls the first transducer in the cleaning machine to work in an alternating high and low frequency mode. The first ultrasonic frequency (e.g., 28kHz) generates a directional microflow to push the thick liquid film in the central region to the edge. In conjunction with the second ultrasonic frequency (e.g., 40kHz), the capillary rise phenomenon in the edge region is suppressed. The two frequencies work together to reduce the thickness difference of the liquid film on the wafer surface. When the upper edge of the wafer reaches the liquid surface, a uniform liquid film distribution is formed, which provides a good foundation for the dynamic dehydration control in the subsequent intermediate lifting stage and effectively reduces the problems of edge residue and local drying differences caused by the unevenness of the initial liquid film.

[0071] The first ultrasonic frequency is 28kHz to 30kHz, and the second ultrasonic frequency is 40kHz to 45kHz. The low-frequency ultrasound (28kHz to 30kHz) generates strong macroscopic disturbances in the liquid, pushing the thick liquid film in the center of the wafer towards the edge, promoting initial homogenization of the liquid film. The high-frequency ultrasound (40kHz to 45kHz) suppresses capillary rise at the edge through fine vibration, reducing excessive accumulation of the liquid film at the edge. The alternating action of these two frequencies during the wafer pulling process at the first speed reduces the thickness difference of the surface liquid film when the upper edge of the wafer reaches the liquid surface, laying a uniform liquid film foundation for dynamic dehydration control in the subsequent mid-pulling stage and reducing residue problems caused by initial liquid film unevenness.

[0072] In some embodiments, the step of continuing to pull the wafer upward at a second speed until the lower edge of the wafer separates from the surface of the cleaning solution includes:

[0073] The wafer is pulled upward at a second speed, and the second transducer in the cleaning machine is controlled to operate at a third ultrasonic frequency until the lower edge of the wafer is separated from the surface of the cleaning solution.

[0074] In this embodiment, during the lifting stage, the second transducer inside the cleaning machine is controlled to operate continuously at a third ultrasonic frequency. Through the cavitation effect and microfluidic action generated by this ultrasonic frequency, the uniform thinning of the surface liquid film in a certain area of ​​the wafer (i.e., the area below the liquid surface) is further promoted. At the same time, the system continues to lift the wafer at a dynamically determined second speed, which can reduce the fluid disturbance to the area exposed to the air interface, balance the dehydration rate between the edge and the center, and ensure that when the lower edge of the wafer leaves the liquid surface, the surface liquid film can break and separate in a more uniform and controllable manner, reducing the risk of local residue and secondary adsorption of particles, and improving the overall drying effect and cleanliness.

[0075] The third ultrasonic frequency is between 1 MHz and 1.3 MHz. This high-frequency ultrasonic wave generates nanoscale vibrations and a fine cavitation effect, forming a uniform acoustic flow field on the wafer surface. This promotes uniform thickness of the liquid film at the molecular scale and suppresses abnormal thinning or rupture of the liquid film caused by edge fluid disturbance. The high-frequency vibration also enhances the uniform distribution of surface tension in the liquid film, assisting in real-time compensation of dehydration differences between the edge and center during dynamic lifting speed. This ensures that when the lower edge of the wafer detaches from the liquid surface, the liquid film peels off uniformly in a controllable manner, reducing the risk of micron-sized droplet residue and particle adsorption with residual liquid.

[0076] In some embodiments, when the wafer is immersed in the cleaning solution, the temperature of the cleaning solution is controlled at a first temperature;

[0077] When the wafer is pulled upward at a first speed, the temperature of the cleaning solution is controlled at a second temperature.

[0078] While the wafer continues to be pulled upward at the second speed, the temperature of the cleaning solution is controlled at the second temperature, which is dynamically determined based on the second speed and is greater than the first temperature.

[0079] In this embodiment, during the immersion stage (when the wafer is statically immersed), the temperature is maintained at a first temperature to facilitate the cleaning solution to fully penetrate the micro-nano defects on the wafer surface and loosen contaminants through moderate swelling. During the initial lifting stage (lifting at a first speed) and the intermediate lifting stage (dynamically lifting at a second speed), the temperature is raised to a higher second temperature. The high temperature reduces the surface tension of the cleaning solution, promoting the flow and spreading of the liquid film on the wafer surface. Combined with ultrasonic vibration and lifting action, the uniformity of the liquid film is enhanced. At the same time, the high temperature environment can accelerate the molecular movement within the liquid film, assisting gravity in overcoming surface adhesion and reducing the problem of slow flow caused by high liquid film viscosity, further reducing the risk of solution residue and particle adsorption.

[0080] Furthermore, the second temperature can be dynamically determined based on the second velocity, reducing the risk of residue caused by uneven liquid film rupture. Combined with the dynamically determined second velocity, it can accommodate differences in surface tension of different cleaning solutions and differences in surface roughness of different wafers. For example, the determination of the second temperature can be based on the following formula:

[0081] T = T0 + 0.3(v-1), (unit: ℃, mm / s);

[0082] T is the second temperature, T0 is the initial temperature (taken as 35℃), and v is the second velocity.

[0083] The first temperature is 25°C to 26°C, and the second temperature is 35°C to 40°C. The synergy between the first and second temperatures ensures effective loosening of pollutants and improves the efficiency of liquid film dehydration, reducing the risk of solution residue and particle adsorption.

[0084] In some embodiments, the first velocity is in the range of 0 mm / s to 0.4 mm / s, and the second velocity is in the range of 0.5 mm / s to 2 mm / s.

[0085] In this embodiment, during the initial lifting stage, the first speed is set in the lower range of 0 mm / s to 0.4 mm / s, and is not zero. This slow lifting provides sufficient time for the ultrasonic synergistic effect, allowing the liquid film to flow uniformly towards the edge under the drive of gravity and ultrasonic microfluidics, thus suppressing edge capillary effects. During the intermediate lifting stage, the second speed is dynamically adjusted to the range of 0.5 mm / s to 2 mm / s. Based on the real-time feedback of the liquid film thickness from the laser interferometer, the speed is reduced in thick film areas (such as the central region) to prolong the time of gravity action, while the lifting speed in thin film areas (such as the edge region) enhances the liquid film peeling efficiency. Simultaneously, it compensates for the dehydration differences between the edge and center caused by fluid disturbance, ensuring uniform thinning of the liquid film throughout the lifting process, laying the foundation for final residue-free drying. This avoids uneven liquid film breakage caused by high-speed lifting and overcomes the problem of insufficient adaptability of traditional uniform-speed processes to different regions and liquid films with different properties, improving drying effect and wafer cleanliness.

[0086] To achieve the above objectives, group experiments were conducted with different ultrasonic frequencies, different pulling speeds, and different cleaning solution temperatures. The thickness difference of the liquid film on the wafer surface and the residual particles on the wafer surface were measured in each group. The measurement results are shown in Table 1 below:

[0087] Table 1

[0088]

[0089] The experiments in groups 1 to 10 show that:

[0090] Compared with Group 1 (40kHz single frequency) and Group 2 (28kHz + 40kHz alternation), the thickness difference decreased from 18.2% to 8.7%, indicating that 28kHz promotes liquid film flow and 40kHz suppresses edge effects. The two work together to make the liquid film distribution more uniform.

[0091] Compared with Group 1 (25℃) and Group 2 (38℃), the particle residue decreased from 22ea to 9ea, indicating that high temperature reduces surface tension (67.8mN / m at 38℃) and enhances dehydration efficiency.

[0092] The optimal group is group 8: dual-frequency ultrasound + adaptive compensation, with a thickness difference of 2.8% between the edge and center of the liquid film and a particle residue of 3. This shows that staged dynamic adjustment + dual-frequency ultrasound can effectively balance gravity and adhesion, solve the problem of uneven liquid film rupture, and meet the dehydration requirements of cleaning solutions with different surface tensions.

[0093] This invention also provides a wafer cleaning and drying apparatus, such as... Figure 2 As shown, it includes:

[0094] Cleaning tank 21, the cleaning tank 21 being filled with cleaning solution;

[0095] Lifting structure;

[0096] The workpiece holder 22 is connected to the lifting structure and is used to support the wafer 23;

[0097] A laser interferometer 24 is disposed at the opening of the cleaning tank 21 and is configured to measure the thickness of the liquid film on the surface of the wafer in real time during the process of the lifting structure lifting the workpiece holder 22 so that the workpiece holder carrying the wafer 23 floats out of the liquid surface of the cleaning solution.

[0098] Speed ​​compensation module 25, which is electrically connected to laser interferometer 24, to obtain the real-time measurement results of laser interferometer 24, and to determine the speed at which the lifting structure lifts the workpiece holder 22 upward based on the real-time measurement results.

[0099] In this embodiment, the thickness of the liquid film on the wafer surface can be monitored in real time using a laser interferometer 24. When the thickness difference between the edge and the center is greater than 10%, the speed compensation module 25 triggers a PID algorithm to adjust the pulling speed (e.g., reducing the speed to 0.5 mm / s at the edge and increasing it to 1.2 mm / s at the center) to control the thickness difference to ≤2.8%, which is more than 90% better than the traditional constant-speed process (thickness difference 30.7%). This avoids uneven liquid film breakage caused by high-speed pulling and overcomes the problem of insufficient adaptability of the traditional uniform-speed process to liquid films of different regions and properties, thus improving the drying effect and wafer cleanliness.

[0100] In some embodiments, the wafer cleaning and drying apparatus further includes a first transducer 26 and a second transducer 27. The first transducer 26 is disposed on both sides of the cleaning tank 21, and the second transducer 27 is disposed at the bottom of the cleaning tank 21. The first transducer 26 can operate alternately using a first ultrasonic frequency and a second ultrasonic frequency, and the second transducer 27 can operate using a third ultrasonic frequency.

[0101] In this way, during the initial lifting stage, while the wafer cleaning and drying device lifts the wafer at a uniform speed at the first speed, the first transducer 26 operates in an alternating high and low frequency mode. It generates directional microflow through the first ultrasonic frequency (e.g., 28kHz) to push the thick liquid film in the central region to flow towards the edge. In conjunction with the second ultrasonic frequency (e.g., 40kHz), it suppresses the capillary rise phenomenon in the edge region. The synergistic effect of the two frequencies reduces the thickness difference of the liquid film on the wafer surface, forming a uniform liquid film distribution when the upper edge of the wafer reaches the liquid surface. This provides a good foundation for the dynamic dehydration control in the subsequent intermediate lifting stage and effectively reduces the problems of edge residue and local drying differences caused by the unevenness of the initial liquid film.

[0102] Furthermore, during the lifting stage, the second transducer 27 operates continuously at the third ultrasonic frequency. Through the cavitation effect and microfluidic action generated by this ultrasonic frequency, the uniform thinning of the surface liquid film in a certain area of ​​the wafer (i.e., the area below the liquid surface) is further promoted. At the same time, the liquid film is measured in real time by the laser interferometer 24, and the speed compensation module 25 dynamically determines the second speed based on the measurement results to continue lifting the wafer. This can reduce the fluid disturbance to the area exposed to the air interface, balance the dehydration rate between the edge and the center, and ensure that when the lower edge of the wafer leaves the liquid surface, the surface liquid film can break and separate in a more uniform and controllable manner, reducing the risk of local residue and secondary adsorption of particles, and improving the overall drying effect and cleanliness.

[0103] Please refer to Figure 3 The present invention also provides an electronic device 30, including a processor 31, a memory 32, and a computer program stored in the memory 32 and executable on the processor 31. When the computer program is executed by the processor 31, it implements the various processes of the above-described wafer cleaning and drying method embodiments and can achieve the same technical effect. To avoid repetition, it will not be described again here.

[0104] This invention also provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, it implements the various processes of the above-described wafer cleaning and drying method embodiments and achieves the same technical effects. To avoid repetition, it will not be described again here.

[0105] The computer-readable storage medium, as defined herein, includes both permanent and non-permanent, removable and non-removable media, and information storage can be achieved by any method or technology. Information can be computer-readable instructions, data structures, program modules, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic magnetic disk storage or other magnetic storage, or any other non-transfer medium that can be used to store information accessible to the terminal device under test. As defined herein, computer-readable storage media does not include transient media, such as modulated data signals and carrier waves.

[0106] This invention also provides a computer program product, including computer instructions that, when executed by a processor, implement the above-described... Figure 1The various processes of the method embodiments shown can achieve the same technical effect, and will not be described again here to avoid repetition.

[0107] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0108] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk), and includes several instructions to cause a terminal (which may be a mobile phone, computer, server, air conditioner, or network device, etc.) to execute the methods described in the various embodiments of the present invention.

[0109] In the various method embodiments of this disclosure, the sequence numbers of each step are not intended to limit the order of the steps. For those skilled in the art, any changes in the order of the steps are within the scope of protection of this disclosure without any creative effort.

[0110] It should be noted that the various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, since the embodiments are basically similar to the product embodiments, the descriptions are relatively simple, and the relevant parts can be referred to the descriptions of the product embodiments.

[0111] The above description represents the preferred embodiments of this disclosure. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles described herein, and these improvements and modifications should also be considered within the scope of protection of this disclosure.

Claims

1. A method for cleaning and drying wafers, characterized in that, The method includes: Immerse the wafer in the cleaning solution for a preset time; Pull the wafer upwards at a first speed until the upper edge of the wafer is on the same plane as the surface of the cleaning solution; The wafer is pulled upward at a second speed until the lower edge of the wafer separates from the surface of the cleaning solution. The second speed is a pulling speed dynamically determined based on real-time measurement results of the liquid film on the wafer surface. Continue to pull the wafer upward at the first speed until the wafer reaches the preset position.

2. The method according to claim 1, characterized in that, The step of continuing to pull the wafer upward at a second speed until the lower edge of the wafer separates from the surface of the cleaning solution includes: The wafer is pulled upwards at the first target speed, and the thickness of the liquid film on the surface of the wafer is measured in real time using a laser interferometer to obtain the real-time measurement result. If the real-time measurement results indicate that the difference between the thickness of the liquid film on the surface of the wafer edge region and the thickness of the liquid film on the surface of the wafer center region is greater than a preset threshold, the first target speed is positively compensated to obtain a second target speed, wherein the second target speed is greater than the first target speed. If the real-time measurement results indicate that the difference between the thickness of the liquid film on the surface of the wafer edge region and the thickness of the liquid film on the surface of the wafer center region is less than or equal to the preset threshold, the first target speed is reverse-compensated to obtain a third target speed, wherein the third target speed is less than the first target speed. The wafer is pulled upward at a second speed until the lower edge of the wafer is separated from the surface of the cleaning solution. The second speed includes the first target speed, the second target speed, and the third target speed.

3. The method according to claim 1, characterized in that, The step of pulling the wafer upward at a first speed until the upper edge of the wafer is on the same plane as the surface of the cleaning solution includes: The wafer is pulled upward at a first speed, and the first transducer is controlled to work alternately at a first ultrasonic frequency and a second ultrasonic frequency until the upper edge of the wafer contacts the surface of the cleaning fluid, wherein the second ultrasonic frequency is greater than the first ultrasonic frequency.

4. The method according to claim 3, characterized in that, The first ultrasonic frequency is 28 kHz to 30 kHz, and the second ultrasonic frequency is 40 kHz to 45 kHz.

5. The method according to claim 1, characterized in that, The step of continuing to pull the wafer upward at a second speed until the lower edge of the wafer separates from the surface of the cleaning solution includes: The wafer is pulled upward at a second speed, and the second transducer is controlled to operate at a third ultrasonic frequency until the lower edge of the wafer is separated from the surface of the cleaning solution.

6. The method according to claim 5, characterized in that, The third ultrasonic frequency is 1 MHz to 1.3 MHz.

7. The method according to any one of claims 1 to 6, characterized in that, When the wafer is immersed in the cleaning solution, the temperature of the cleaning solution is controlled at a first temperature; When the wafer is pulled upward at a first speed, the temperature of the cleaning solution is controlled at a second temperature. While the wafer continues to be pulled upward at the second speed, the temperature of the cleaning solution is controlled at the second temperature, which is dynamically determined based on the second speed and is greater than the first temperature.

8. The method according to claim 7, characterized in that, The first temperature is 25°C to 26°C, and the second temperature is 35°C to 40°C.

9. The method according to any one of claims 1 to 6, characterized in that, The first velocity is in the range of 0 mm / s to 0.4 mm / s, and the second velocity is in the range of 0.5 mm / s to 2 mm / s.

10. A wafer cleaning and drying apparatus, characterized in that, The device includes: A cleaning tank filled with cleaning fluid; Lifting structure; The workpiece holder connected to the lifting structure is used to carry the wafer; A laser interferometer is disposed at the opening of the cleaning tank and configured to measure the thickness of the liquid film on the surface of the wafer in real time during the process of the lifting structure lifting the workpiece holder so that the workpiece holder carries the wafer and floats out of the liquid surface of the cleaning solution. A speed compensation module is electrically connected to the laser interferometer to obtain the real-time measurement results of the laser interferometer and determine the speed at which the lifting structure lifts the workpiece frame upward based on the real-time measurement results.

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