Single-chip cleaning device and method

Abstract

The invention provides a single-chip cleaning device and method, and belongs to the field of semiconductor manufacturing equipment and processes. The device comprises a rotary bearing unit, a center and edge fluid conveying system and a control unit, after first treatment liquid is supplied through a center nozzle to achieve wafer surface hydrophobization, liquid supply is stopped immediately, center liquid supply is forbidden, an edge rocker arm accurately positions the nozzle to the specific radial position of the wafer edge, oxidizing second treatment liquid is output in a high-flux mode, and the wafer surface hydrophobization is achieved. And synchronously increasing the rotating speed of the wafer to a high rotating speed for generating strong centrifugal shearing force. The hydrophobic surface is rapidly hydrophilized through chemical oxidation modification, a one-way laminar flow field is formed in combination with centrifugal washing, residual liquid medicine and reaction products on the edge are thoroughly removed, and secondary etching damage is avoided.

Description

Technical Field

[0001] This disclosure relates to the field of semiconductor manufacturing equipment and processes, and in particular to a single-wafer cleaning apparatus and method. Background Technology

[0002] In modern semiconductor manufacturing processes, as feature sizes continue to shrink and device structures evolve from two-dimensional planar to three-dimensional stacked structures, wet cleaning processes, as the cornerstone of ensuring yield, have become exponentially more technically challenging. Of the hundreds of processes in integrated circuit manufacturing, cleaning accounts for approximately 30%, making it the most frequently repeated process step. Single-wafer cleaning machines, with their precise control over the flow field, chemical reaction kinetics, and particle removal efficiency of a single wafer, have completely replaced tank cleaning machines as the mainstream choice for critical cleaning steps, especially in front-end and mid-end processes. Among numerous cleaning chemicals, dilute hydrofluoric acid (DHF) is widely used to remove native oxide layers, sacrificial oxide layers, or residual hard mask layers due to its extremely high selective etching ability on silicon dioxide (SiO2). However, DHF treatment is accompanied by a key physicochemical change: as the surface silicon oxide is removed, the exposed single-crystal silicon surface is passivated by hydrogen atoms, resulting in a sharp drop in wafer surface energy and a sudden change in contact angle from a hydrophilic state (less than 5 degrees) to a strongly hydrophobic state (greater than 60 degrees). This instantaneous reversal of surface properties completely alters the fluid's movement behavior on the wafer surface, causing the continuous liquid film to rupture and shrink into discrete droplets.

[0003] Existing technologies for cleaning after DHF hydrophobication primarily follow the standard "center-spray-centrifugal spreading" model. However, this model faces significant technical bottlenecks when treating hydrophobic surfaces. The first common strategy involves switching between deionized water (DIW) and ozone water (O3W) directly through the center nozzle after DHF treatment stops. This approach suffers from "transit time effect" and "kinetic energy decay." The fluid takes time to reach the edge from the center, and due to the repulsive effect of the hydrophobic surface, the centrally sprayed fluid struggles to create an effective "bulldozer" effect to push away residual droplets at the edge; instead, it often slides over the droplets, causing them to stagnate. Furthermore, the radial velocity of the centrally injected water decreases significantly by the time it reaches the edge, failing to provide sufficient shear stress to overcome the adhesion of the hydrophobic droplets. The second strategy employs a process of "stopping DHF treatment - direct high-speed spin-drying - full-area ozone water treatment." While this method attempts to avoid watermarks through spin-drying, it ignores the complex fluid dynamics of the edge region. At the physical edge of a wafer, the interaction between airflow and liquid flow creates intense turbulent vortices. Simple spin drying often results in droplets containing high concentrations of reaction products (such as fluorosilicates) being "captured" at the edge, forming difficult-to-remove "watermarks" or "silicate spots" after drying. Once these residues dry, their chemical bonds are extremely strong, making them difficult to remove with subsequent conventional cleaning.

[0004] The aforementioned technical defects manifest as a failure mode known as "Edge Pattern" in actual production. According to feedback data from wafer surface defect detectors, this defect appears as high-density clusters of particles or cloud-like blemishes near the wafer edge repulsion zone. Microscopic analysis reveals that these defects are actually caused by localized over-etching or reaction product precipitation due to residual DHF droplets. Because DHF is highly corrosive, even minute amounts of residual droplets can cause irreversible damage to intricate nanopatterns, such as open circuits at contacts, leading to significant yield losses. This is especially true in devices with extremely high aspect ratios, where edge residues are more likely to cause interlayer short circuits or structural collapse. While existing yield management systems can automatically identify these defects through defect classification, they cannot eliminate their origin. Therefore, the industry urgently needs an innovative cleaning solution that can overcome the fluid instability of hydrophobic surfaces and achieve complete removal of edge residues. Summary of the Invention

[0005] This disclosure aims to solve the core technical problem of existing single-wafer cleaning technologies after the DHF process, where the hydrophobicity of the wafer surface leads to chemical residues, accumulation, splashing, and secondary reactions in the edge regions, resulting in abnormal edge patterns and excessive local light scattering. This disclosure provides a device and method for completely eliminating edge residues from both physical and chemical perspectives by creatively introducing an "instant edge blocking" timing sequence and a "high-energy oxidation flow field" reconstruction mechanism.

[0006] To achieve the above objectives, this disclosure provides a single-wafer cleaning device with a hardware architecture specifically optimized to support complex edge processing logic. The device includes: a precision-controlled rotating support unit for providing a wide range of variable rotational speeds and high accelerations; a central fluid delivery system responsible for routine full-wafer processing; and a core edge fluid delivery system. The edge fluid delivery system is not merely an auxiliary nozzle, but an independently controlled process module, comprising a high-speed servo-driven edge rocker arm and flow-rate edge nozzles with a specially designed flow path. The control unit is configured with a unique process algorithm: at the moment the DHF process ends, logically prohibiting the intervention of any low-kinetic-energy central fluid, it immediately triggers the edge system to precisely deliver the nozzles to a critical fluid dynamic point—a certain proportional distance from the edge (preferably R / 3 position)—and simultaneously invokes a combination of process parameters (flow rate and high rotational speed). This position is selected based on fluid dynamics analysis, located upstream of the critical transition zone from laminar to turbulent flow, ensuring that the injected high-energy fluid can completely cover and flush all possible stagnation areas downstream. Furthermore, the device uses high-purity PFA material to construct the entire fluid loop to ensure cleanliness and durability under strong acid and strong oxidizing environments.

[0007] This disclosure also provides a cleaning method based on the aforementioned apparatus, which redefines the standard operating procedure for cleaning hydrophobic surfaces. Its core step involves using a high-concentration ozone-water stream inserted at a specific location within the "golden window" after DHF treatment. This method utilizes the strong oxidizing properties of ozone water to modify the edge hydrophobic silica surface into a hydrophilic silica surface within milliseconds, fundamentally disrupting the interfacial mechanics basis for the existence of hydrophobic droplets (i.e., droplet contraction due to the principle of minimum Gibbs free energy). Simultaneously, the powerful centrifugal shear force generated by high rotation speed and the momentum of the "liquid wall" spreading outward from the target location physically forcefully remove any potential residues or splash droplets. This simultaneous "chemical modification + physical rinsing" mechanism effectively overcomes the limitations of single mechanisms in traditional methods.

[0008] This disclosure offers significant advantages over existing technologies: First, it completely eliminates edge cluster defects. Experimental data shows that, using this solution, the incidence of edge pattern anomalies drops from a significant proportion in traditional processes to near zero. This is crucial for advanced processes aiming for the highest yield. Second, it significantly improves flow field stability and anti-splashing capabilities. Through targeted spraying at specific edge locations, this disclosure constructs a stable unidirectional laminar centrifugal flow field in the outer annular region of the wafer where problems are most likely to occur, effectively suppressing aerosol splashing caused by edge turbulence. Third, it broadens the process window. The combination of flow rate and high rotation speed provides greater robustness to the cleaning process, enabling it to adapt to surface conditions with varying degrees of hydrophobicity and reducing sensitivity to fluctuations in upstream processes. Finally, it effectively prevents secondary contamination. By prioritizing the edge, it avoids the risk of bringing edge contaminants back to the central region, ensuring uniform cleanliness across the entire wafer surface. Attached Figure Description

[0009] Figure 1 The image shows a defect distribution map generated by a particle counter scan on the wafer surface after using the standard DHF cleaning process in the prior art. A high density of edge defects is clearly visible in the lower left corner of the image.

[0010] Figure 2 It shows Figure 1 The enlarged schematic diagram of the area within the dashed line shows the typical cluster-like defect morphology caused by DHF residue.

[0011] Figure 3 The diagram shows a top view of a single-piece cleaning device according to an embodiment of the present invention, which illustrates in detail the spatial geometric relationship between the edge rocker arm and the edge nozzle at the working position of the target edge.

[0012] Figure 4 The diagram shows the surface defect distribution of a wafer obtained under the same experimental conditions after applying the technical solution of this invention.

[0013] Figure 5 A schematic flowchart of the single-wafer cleaning method provided in an embodiment of the present invention is shown. Detailed Implementation

[0014] The technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings.

[0015] In this specification and claims, specific terms have the following meanings: DHF (Dilute Hydrofluoric Acid) refers to a solution of hydrofluoric acid and ultrapure water in a specific ratio, used for etching silicon oxide. O3W (Ozone Water) refers to an oxidizing solution formed by dissolving high-purity ozone gas in deionized water. R / 3 position refers to a location on the radial coordinate system approximately one-third of the wafer radius from the physical edge of the wafer. Edge Pattern specifically refers to patterned defects or particle aggregations remaining in the wafer edge region after the cleaning process, caused by chemical residues or uneven etching.

[0016] This embodiment details a single-piece cleaning device 100 specifically designed to address the problem of hydrophobic residue at edges. This single-piece cleaning device 100 integrates the latest advancements in precision mechanical engineering, fluid dynamics control, and chemical reaction engineering, aiming to provide a highly reliable and efficient cleaning platform. See also... Figure 3 The core of the single-wafer cleaning unit 100 is a high-performance rotating support unit 10, which horizontally supports the wafer and drives it to rotate around a vertical central axis. Unlike traditional belt drives or low-end direct-drive motors, this embodiment employs advanced hollow-shaft magnetic levitation direct-drive motor technology. This motor utilizes Lorentz force to achieve non-contact levitation of the rotor, completely eliminating friction and wear of mechanical bearings, thereby avoiding the generation of particulate matter, which is crucial for the cleanroom environment of advanced processes. The magnetic levitation system, through a built-in high-frequency displacement sensor and active magnetic bearing controller, can monitor and compensate for the axial and radial vibrations of the rotor in real time, controlling the rotor runout to the micrometer level, typically less than 10 micrometers. This extreme stability is the hardware foundation for achieving the "instantaneous high acceleration" process requirement of this disclosure. The motor can provide extremely high torque, supporting stepless speed regulation from 0 to 3000 rpm, and acceleration up to 5000 rpm / s or even higher. This high dynamic response capability allows the cleaning process to complete speed switching in a very short time, maximizing the use of inertial forces to remove surface droplets.

[0017] The rotating bearing unit 10 has six pneumatic clamping pins 11 along its edge. To withstand harsh chemical environments such as strong acids (e.g., DHF) and strong oxidants (e.g., ozone water), the main body of the clamping pins 11 is made of high-strength PEEK (polyetheretherketone), and the part in contact with the wafer is inlaid with high-purity perfluoroalkoxy resin (PFA). PFA material is not only corrosion-resistant, but its extremely low surface energy makes it difficult for DHF solutions to adhere to its surface, significantly reducing secondary pollution sources.

[0018] The core hardware innovation of this disclosure lies in the edge fluid delivery system. It is not a simple auxiliary nozzle, but a self-operating precision subsystem designed to accurately reconstruct the flow field in the edge region. The edge rocker arm 20 is driven by a high-resolution servo motor with a motion trajectory accuracy of ±0.1 mm. An electronic cam curve is pre-set in the control unit 50 of the single-piece cleaning device 100, ensuring that the edge rocker arm 20 can switch rapidly between the standby and processing positions with an optimal acceleration curve. To meet the "immediate intervention" process requirement of this disclosure, the total stroke time of the edge rocker arm 20 from the standby position to the target edge working position is strictly controlled to within 0.5 seconds, and even as low as 0.3 seconds. This rapid response is designed to occupy a favorable hydrodynamic position the instantaneously after DHF treatment stops.

[0019] The edge nozzle 30 is a key actuator for flow field reconstruction. As detailed below, the edge nozzle 30 supplies a second processing fluid with oxidizing capabilities to the off-center region of the wafer. Conventional pinhole nozzles produce extremely fine, high-speed jets at high flow rates, which can easily lead to sputtering or even damage to the fine patterns on the wafer surface. The edge nozzle 30 in this embodiment employs a special fan-shaped wide-angle design. Its internal flow channels are optimized by computational fluid dynamics, are gradually expanding, and a flow straightening structure is set before the outlet to eliminate swirl. This design allows the fluid to form a "liquid curtain" at the outlet that is approximately 20 mm to 40 mm wide, uniform in thickness, and has a consistent velocity vector. This design allows the impact pressure of the fluid to remain within a safe range at extremely high flow rates, for example, from 1.4 L / min to 2.5 L / min, while ensuring coverage area. In terms of jet geometry, the edge nozzle 30 is not mounted vertically downwards. Its jet axis forms an angle of 10 degrees to 50 degrees with the vertical, preferably 30 degrees, and its direction is strictly directed towards the outside of the wafer. This "centrifugal tilt" design ensures that the fluid has a significant radial outward velocity the moment it contacts the wafer, physically eliminating the possibility of the solution flowing back to the center of the wafer. This is crucial for preventing the central area from being contaminated by high concentrations of residues at the edges.

[0020] To meet the flow requirements of the edge nozzles, the chemical supply system has been specially enhanced. The system employs an all-PFA material flow path, including pumps, valves, piping, and connectors, to ensure zero metal ion deposition. In particular, high-response pneumatic diaphragm valves with an opening time of less than 50 milliseconds are selected. The system is equipped with a high-precision ultrasonic flow meter capable of measuring pulsating flow and its instantaneous values ​​in real time. The control unit incorporates an advanced PID flow control loop. Unlike traditional open-loop control, this PID loop can stabilize the flow rate at the set value, such as 1.4 liters / minute, within 0.2 seconds of valve opening, with an error controlled within ±0.05 liters / minute. This millisecond-level flow response is crucial for short-duration edge impact processes lasting only 5 to 15 seconds, ensuring that every drop of chemical reaches the wafer surface at the right time and at the right speed. Furthermore, the system integrates a pressure sensor to monitor nozzle back pressure; if an abnormal pressure is detected, indicating nozzle blockage or piping leakage, a safety interlock mechanism will be immediately triggered.

[0021] Regarding the process flow, this embodiment will explain in detail the cleaning method proposed in this disclosure, especially how to eliminate edge defects through strict timing control and parameter coordination, utilizing a physicochemical coupling mechanism. The entire process can be divided into three main stages.

[0022] The first stage is surface hydrophobication treatment. In this stage, the single-piece cleaning device 100 performs a standard oxide layer removal process. For this, the central fluid delivery system includes at least one central nozzle 40, such as... Figure 3As shown, the central nozzle 40 is positioned above the geometric center of the wafer to supply a first processing solution to the wafer surface for etching and forming a hydrophobic surface. Specifically, the control unit 50 of the single-wafer cleaning device 100 controls the central nozzle 40 to descend to the working position, while the rotating carrier unit 10 maintains a low speed. The rotation speed is typically set between 200 rpm and 500 rpm, preferably 300 rpm, the DHF (dilution ratio 100:1) flow rate is set to 1.0 L / min, and the duration is approximately 15 to 30 seconds. During this stage, HF molecules diffuse to the wafer surface and react chemically with the native oxide layer (SiO2) to generate water-soluble hexafluorosilicic acid (H2SiF6) and water. As the oxide layer is peeled off layer by layer, the underlying monocrystalline silicon lattice is exposed. Due to the presence of hydrogen ions in the HF solution, the surface dangling bonds are rapidly saturated with hydrogen atoms, forming Si-H bonds. This chemical change leads to a sharp decrease in surface free energy, resulting in strong hydrophobicity. At this point, the DHF solution can no longer maintain a continuous liquid film on the wafer surface, instead breaking down and shrinking into numerous free droplets. At a low centrifugal force of 300 rpm, these droplets are primarily controlled by gravity and adhesion, slowly moving towards the edge and easily accumulating there. The low rotation speed is chosen to prevent the hydrophobic droplets from breaking into tiny aerosols due to excessive air shear force upon detachment from the surface; these aerosols, if they were to re-deposit on the surface, would form a difficult-to-remove contaminant.

[0023] The second stage is edge flow field reconstruction and strong oxidation intervention, which is the most crucial "golden operating window" of this disclosure. At the moment T0 when the DHF flow rate reaches zero, the control unit 50 of the single-wafer cleaning device 100 immediately triggers a concurrent command sequence. First, the control logic explicitly includes a "dead time," strictly prohibiting the central nozzle 40 from spraying any fluid, such as DIW. This is based on fluid dynamics considerations: the low-speed water flow injected at the center will cause severe "slippage" on the hydrophobic surface, resulting in extremely low coupling efficiency between the fluid and the wafer surface, making it impossible to effectively transfer momentum to propel the DHF droplets stuck at the edge. On the contrary, the impact of the low-energy water flow may cause large droplets at the edge to break into more difficult-to-remove microdroplets. Second, the control unit 50 of the single-wafer cleaning device 100 controls the edge rocker arm 20 to quickly move to the target edge working position within T0+0.3 seconds, and controls the edge nozzle 30 to output the second processing fluid at a flow rate capable of forming a continuous liquid film covering the wafer edge region. The target edge working position is located within a radial distance range of 20% to 45% of the radius of the physical edge of the wafer. In this embodiment, this position is precisely defined as R / 3. The selection of the R / 3 position is not arbitrary but based on Reynolds number calculations. In the rotating disk flow field, there is a critical radius for the fluid to transition from laminar to turbulent flow. The R / 3 position is usually upstream of this critical region. Injecting fluid at this location ensures that the fluid, as it spreads outward, can form a stable liquid film covering all potential downstream turbulent stagnation zones, acting like a advancing "wall" to sweep away all impurities. In other words, the target edge working position is such that the second processing fluid ejected from the edge nozzle 30, under the action of centrifugal shear force, forms a centrifugal flow field that diffuses unidirectionally from the target edge working position to the physical edge of the wafer. Simultaneously, the control unit 50 of the single-piece cleaning device 100 controls the rotating bearing unit 10 to increase its rotational speed from a first speed of 300 rpm to a second speed between 800 rpm and 1500 rpm at an angular acceleration of 1500 rpm to 5000 rpm. This second speed drives the liquid film to generate centrifugal shear force sufficient to overcome the pinning effect of residual droplets on the hydrophobic surface. Furthermore, this step-like acceleration aims to break the static equilibrium of the droplets using the impact force generated by the rate of acceleration change. Finally, the edge nozzle 30 opens instantaneously upon reaching its position, outputting O3W at a concentration of 20 ppm to 50 ppm, with the flow rate forcibly locked at a high level of 1.4 L / min to 2.5 L / min.

[0024] The physicochemical mechanism at this stage involves two aspects. First, chemical modification. Ozone water at concentrations above 20 ppm possesses extremely high redox potentials. When it comes into contact with the residual hydrophobic silicon surface at the edge, ozone molecules rapidly decompose to produce monatomic oxygen or hydroxyl radicals, which react with Si-H bonds to generate Si-OH and oxygen. This reaction is extremely fast, growing a chemical oxide layer of approximately 3-5 angstroms on the silicon surface within milliseconds. This oxide layer is rich in hydroxyl groups and is extremely hydrophilic. This surface hydrophilization instantly alters the Young's contact angle of the residual DHF droplets, causing it to plummet from over 60 degrees to less than 10 degrees. This fundamentally disrupts the mechanical basis for the droplets to maintain their spherical shape, causing them to rapidly spread and integrate into the mainstream O3W liquid film, thus being diluted and carried away. Second, high-energy physical scouring. High rotation speeds above 800 rpm generate a huge centrifugal force field at the R / 3 position. With a flow rate exceeding 1.4 liters per minute, the O3W forms a thick (greater than 100 micrometers thick) and high-speed moving "liquid wall" at the wafer edge. According to boundary layer theory, this liquid wall possesses extremely high momentum, capable of applying strong shear stress to the wafer edge. Based on the removal torque model, when the removal torque generated by the shear force exceeds the adhesion torque of the particles or droplets, the residue is peeled off. This disclosure ensures that the shear stress far exceeds the pinning force of the hydrophobic droplets through the product effect of high rotational speed and flow rate, thereby achieving physically forced removal.

[0025] In addition, the control unit 50 may also include a flow monitoring module for real-time monitoring of the instantaneous flow rate of the second processing fluid, and triggering an alarm or pausing the process when the monitored instantaneous flow rate is lower than a preset process threshold.

[0026] The third stage is full-film purification and drying. After the edge crisis is resolved, the process enters the routine full-film cleaning stage to ensure overall cleanliness. The edge nozzles are closed and retracted, while the center nozzle 40° is opened. The system alternately sprays SC-1 solution or O3W, combined with megasonic cleaning for full-film cleaning. This step is to remove trace particles that may have fallen into the central area due to airflow disturbance and to perform a final oxidation treatment on the entire film, ensuring a uniform surface condition. Finally, a DIW rinse is performed, followed by a high-speed spin-drying stage. Since the edge area has been thoroughly hydrophilized in the second stage, the water film shrinks evenly during drying, completely eliminating the risk of watermarks.

[0027] To objectively evaluate the technical effectiveness of this disclosure, a series of rigorous comparative experiments were conducted on a 300mm wafer advanced process production line. The experimental subjects were wafers with residual hydrophobic slurry on their surface after CMP (Chemical Mechanical Polishing), with a focus on examining defects in the edge regions. The reference group adopted the industry-standard process, i.e., stopping DHF treatment and then spraying O3W through the center nozzle 40. Experimental group A only optimized the DHF parameters, without introducing edge treatment, and reduced the DHF rotation speed to 300 rpm. Experimental group B adopted the scheme of this disclosure, immediately introducing the edge rocker arm 20 at the R / 3 position for high-flow, high-speed rinsing after DHF treatment. A full-wafer scan was performed using a surface defect scanner. The results showed that the reference group had serious defects, such as… Figure 1 and Figure 2 As shown, the scanning electron microscope image reveals a distinct high-density defect cloud C at the edge of wafer W, confirmed to be fluorosilicate residue. This not only affects yield quality but also influences the interpretation of the contamination particle count—inferiorly inflating the particle count. Experimental group A showed improvement, reducing the defect number to approximately 50. Lowering the DHF rotation speed reduced initial aerosol splashing, but the fluid dynamics retention problem remained. Experimental group B achieved complete defect elimination; the high-energy edge flow field thoroughly resolved the residue issue, and the edge cleanliness was consistent with the central region. Figure 4 As shown.

[0028] In-depth data analysis reveals the double-edged sword effect of rotational speed and the limitations of center flushing. A comparison between the control group and experimental group A shows that reducing the rotational speed is beneficial during the DHF stage. This is because in the early stages of hydrophobic surface formation, excessive centrifugal force causes droplets to prematurely detach from the surface and enter the air, forming aerosols. These aerosols randomly fall back, causing secondary contamination. Therefore, this disclosure adheres to a low rotational speed strategy during the DHF stage. Although experimental group A showed improvement, it still had a 5% failure rate, proving that relying solely on the center nozzle 40 cannot completely eliminate hydrophobic residue at the edges. As the fluid flows from the center to the edge, its kinetic energy is significantly reduced due to frictional losses, reaching the edge with insufficient strength to overcome the pinning force of the hydrophobic surface. Experimental group B achieved "zero defects," thanks to the synergistic effect of three factors: R / 3 position, 800 rpm rotational speed, and 1.4 L / min flow rate. The R / 3 position ensures complete fluid coverage of the outer third of the critical area; 800 rpm provides the necessary centrifugal shear force to prevent droplet retention; and 1.4 L / min provides sufficient medium flux to form a thick liquid film to encapsulate and dilute residues. All three parameters are indispensable. Increasing the rotation speed alone without sufficient flow may lead to film rupture and the formation of dry spots; insufficient flow without sufficient rotation speed results in insufficient shear force to physically remove stubborn particles. Microscopic morphology analysis further confirms this. Defects in the reference group exhibit typical "silicate precipitation" characteristics, accompanied by slight roughening of the silicon surface, which is chemical corrosion damage caused by the long-term residence and concentration of DHF droplets. In contrast, the edge region after applying this disclosure shows clearly visible atomic steps on the surface, without any precipitation or etching pits, proving that residual droplets were completely removed by the rapid intervention mechanism of this disclosure before causing damage.

[0029] The core idea of ​​this disclosure lies in "edge flow field reconstruction," and its specific implementation is not limited to the single process described above, but can be flexibly adjusted according to actual process requirements. For example, on some extremely hydrophobic surfaces, such as photoresist surfaces, simple liquid rinsing may still be insufficient. As a variant, this embodiment can add a nitrogen nozzle next to the edge nozzle, or directly use a nozzle containing both fluids. A high-speed nitrogen flow is used in conjunction with the O3W jet. This gas-liquid mixed jet can generate an ultrasonic excitation effect, producing microbubble cavitation, further improving the removal efficiency of nanoscale particles, while the airflow helps to push the liquid towards the edge more quickly. For next-generation ultra-large wafers with a diameter of 450 mm, a single R / 3 position may not be sufficient to cover the wide edge band. In this case, the control unit can be programmed to execute a "dynamic scanning" mode. During the 15-second edge processing time, the edge rocker arm 20 continuously moves from the R / 2 position to the edge position, while the rotation speed linearly increases from 800 rpm to 1200 rpm. This dynamic scanning strategy ensures optimal linear velocity and fluid impact angle for every inch of the edge area from the inside out, avoiding jet shadows that may occur with fixed positions. While this embodiment primarily discusses O3W treatment after DHF, this single-wafer cleaning device 100 is also applicable to treatments after other hydrophobic processes. For example, the edge flow rinsing logic of this disclosure can also be used after using buffered hydrofluoric acid or buffered oxide etching solution. In this case, the second treatment solution can be replaced with dilute ammonia or DIW with added surfactants to adjust the surface zeta potential and prevent particle re-adsorption using electrostatic repulsion.

[0030] The control unit 50 disclosed herein can be further upgraded to an intelligent control unit. By collecting a large amount of historical process data, including flow rate, rotation speed, defect rate, etc., a flow field model is established using machine learning algorithms (such as random forests or neural networks). The system can automatically fine-tune the edge jetting parameters based on the real-time monitored DHF etching time (reflecting the surface hydrophobicity). For example, if a batch of wafers is found to have a thick oxide layer, a long DHF etching time, and extremely high surface hydrophobicity, the control unit 50 will automatically increase the edge jetting flow rate from 1.4 liters / minute to 1.8 liters / minute and the rotation speed to 1000 rpm to cope with more severe residue challenges. This adaptive control capability significantly improves the yield stability of the equipment in multi-variety, small-batch production environments.

[0031] This disclosure also relates to airflow control in the single-wafer cleaning apparatus 100. During high-speed rotation, the wafer edge exhibits extremely high linear velocity, easily inducing strong air turbulence. To address this, the single-wafer cleaning apparatus 100 is equipped with a high-efficiency fan filter unit, forming a uniform, vertically downward laminar flow within the cleaning chamber. The airflow velocity is precisely calculated and controlled, typically between 0.3 m / s and 0.5 m / s. This stable vertical airflow acts as an "air curtain," suppressing the upward airflow and vortices caused by wafer rotation, preventing waste liquid ejected from the wafer edge from splashing back onto the wafer surface as aerosol. Simultaneously, the airflow also helps to rapidly expel volatile chemicals from the chamber, ensuring the cleanliness of the process environment.

[0032] Accordingly, see Figure 5 This disclosure also provides a single-wafer cleaning method, which is performed using the single-wafer cleaning device 100 of the foregoing embodiments. The method includes the following steps S501, S502 and S503.

[0033] S501: The first processing liquid is supplied to the rotating wafer surface through the central nozzle to etch the wafer surface and form a hydrophobic surface.

[0034] S501: After stopping the supply of the first processing liquid, control the edge rocker arm to move the edge nozzle to the target edge working position.

[0035] S501: Control the rotating bearing unit to increase the wafer rotation speed to the second rotation speed, and at the same time supply the second processing liquid to the wafer through the edge nozzle at the flow rate.

[0036] The aforementioned target edge working position is such that the second processing liquid ejected from the edge nozzle forms a centrifugal flow field that diffuses unidirectionally from the target edge working position to the physical edge of the wafer under the action of the centrifugal shear force.

[0037] In summary, this disclosure solves the long-standing problem of hydrophobic edge residue in semiconductor cleaning processes through a sophisticated electromechanical-hydraulic integrated system. Its technical solution is based on fluid dynamics and surface chemistry theories, and experimental data demonstrates its significant value in improving yield. This invention is not only applicable to current 12-inch wafer manufacturing but also provides crucial edge control capabilities for future 18-inch wafer cleaning technologies, exhibiting extremely high industrial application prospects.

[0038] It should be noted that the technical solutions described in the embodiments of this disclosure can be combined arbitrarily without conflict.

[0039] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A single-piece cleaning device, characterized in that, include: A rotating support unit is configured to horizontally support the wafer and drive the wafer to rotate about a vertical central axis; A central fluid delivery system includes at least one central nozzle positioned above the geometric center of the wafer for supplying a first processing fluid to the wafer surface to etch the wafer surface and form a hydrophobic surface. An edge fluid delivery system, set independently of the central fluid delivery system, includes an independently drivable edge rocker arm and an edge nozzle disposed at the end of the edge rocker arm, the edge nozzle being configured to supply a second processing liquid with oxidizing capabilities to the non-central region of the wafer; as well as The control unit is communicatively connected to the rotating bearing unit, the central fluid delivery system, and the edge fluid delivery system. The control unit is configured to, after controlling the central nozzle to stop outputting the first processing liquid to complete the hydrophobic treatment, control the edge rocker arm to position the edge nozzle to the target edge working position, and control the edge nozzle to output the second processing liquid at a flow rate capable of forming a continuous liquid film covering the wafer edge region. At the same time, the control unit controls the rotating bearing unit to increase the wafer rotation speed to a second rotation speed, which can drive the liquid film to generate a centrifugal shear force sufficient to overcome the residual droplet pinning effect on the hydrophobic surface. The target edge working position is such that the second processing liquid ejected from the edge nozzle forms a centrifugal flow field that diffuses unidirectionally from the target edge working position to the physical edge of the wafer under the action of the centrifugal shear force.

2. The single-piece cleaning device according to claim 1, characterized in that, The target edge working position is located within a radial distance range of 20% to 45% of the radius of the physical edge of the wafer.

3. The single-piece cleaning device according to claim 1, characterized in that, The edge nozzle is configured as a fan-shaped wide-angle nozzle.

4. The single-piece cleaning device according to claim 1, characterized in that, The control unit is configured to implement a zero-flow waiting strategy during the time interval between the cessation of the first processing fluid output and the commencement of the second processing fluid output, in order to prevent the central fluid delivery system from outputting any fluid to the wafer surface.

5. The single-piece cleaning device according to claim 1, characterized in that, The second rotational speed is set to a range of 800 rpm to 1500 rpm, and the control unit is configured to accelerate the wafer from the first rotational speed during the hydrophobication process to the second rotational speed at an angular acceleration of 1500 rpm to 5000 rpm.

6. The single-piece cleaning device according to claim 1, characterized in that, The control unit also includes a flow monitoring module, which is used to monitor the instantaneous flow rate of the second processing liquid in real time, and to trigger an alarm or suspend the process when the monitored instantaneous flow rate is lower than a preset process threshold.

7. The single-piece cleaning device according to claim 1, characterized in that, The first treatment solution is an aqueous solution of hydrofluoric acid with a dilution ratio of 500:1 to 10:1, and the second treatment solution is ultrapure water containing 10 ppm to 80 ppm ozone gas.

8. The single-piece cleaning device according to claim 1, characterized in that, The device also includes an airflow control unit located above the rotating bearing unit, the airflow control unit being configured to provide a constant and uniform vertical laminar flow during operation of the edge nozzles.

9. The single-piece cleaning device according to claim 1, characterized in that, The rotating bearing unit is driven by a hollow shaft magnetic levitation motor, and the control unit has a built-in PID control algorithm to suppress axial runout and radial vibration during sudden changes in rotational speed.

10. A single-wafer cleaning method, characterized in that, The method is performed using a single-wafer cleaning device according to any one of claims 1 to 9, the method comprising: The first processing liquid is supplied to the rotating wafer surface through the central nozzle to etch the wafer surface and form a hydrophobic surface. After stopping the supply of the first processing liquid, control the edge rocker arm to move the edge nozzle to the target edge working position; The rotating support unit is controlled to increase the wafer rotation speed to the second rotation speed, while the second processing fluid is supplied to the wafer at the specified flow rate through the edge nozzle. The target edge working position is such that the second processing liquid ejected from the edge nozzle forms a centrifugal flow field that diffuses unidirectionally from the target edge working position to the physical edge of the wafer under the action of centrifugal shear force.

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