Wafer edge etching device and method based on gravity adaptive limiting

Abstract

The invention provides a wafer edge etching device and method based on gravity adaptive limiting. The device comprises a lower chamber; the upper chamber is positioned above the lower chamber and can perform opening and closing movement relative to the lower chamber so as to form a closed etching environment; each limiting mechanism comprises a rotating shaft and an L-shaped swing arm rotating around the rotating shaft, the L-shaped swing arm is configured to be kept at an outward opening position under the action of gravity torque of the L-shaped swing arm under the first state that the wafer is not placed, so that a channel for placing the wafer is formed, and the L-shaped swing arm is further configured to be kept at the outward opening position under the action of gravity torque of the L-shaped swing arm under the action of gravity torque of the L-shaped swing arm. And when the wafer is placed in the lower cavity and is in contact with the L-shaped swing arm, the L-shaped swing arm rotates around the rotating shaft to a second state under the action of the gravity of the wafer, and the edge of the wafer is flexibly limited and centered by utilizing the inner side surface of the L-shaped swing arm.

Description

Technical Field

[0001] This disclosure relates to the field of semiconductor manufacturing equipment and process technology, and more specifically, to a wafer edge etching apparatus and method based on gravity adaptive positioning. Background Technology

[0002] In modern semiconductor integrated circuit manufacturing, epitaxial wafer production is a crucial link between substrate fabrication and device manufacturing. To meet the stringent electrical performance requirements of high-performance power devices and high-end logic chips, heavily doped wafers are typically chosen as substrates. However, during high-temperature epitaxial growth, the high concentration of impurity atoms (such as boron, arsenic, and phosphorus) within the heavily doped substrate easily volatilizes into the reaction chamber and deposits on the growing epitaxial layer, leading to abnormal resistivity distribution—a phenomenon known as the "auto-doping effect." To suppress this effect, the industry commonly employs the method of depositing a silicon oxide (SiO2) or silicon nitride (Si3N4) sealing film on the back side of the substrate. However, the inherent diffraction characteristics of chemical vapor deposition (CVD) mean that the sealing film inevitably covers the sides and front edge areas of the wafer. If these edge deposits are not removed, they will cause lattice mismatch, polycrystalline nucleation, or stress concentration during subsequent epitaxial layer growth, ultimately resulting in severe edge defects. Therefore, edge etching has become the last line of defense for yield control.

[0003] Existing edge etching equipment primarily relies on mechanical positioning mechanisms to ensure wafer alignment accuracy within the reaction chamber, thereby guaranteeing uniform etching width. The current mainstream approach employs cylindrical mechanical positioning posts distributed around the chamber. These posts are typically made of corrosion-resistant hard materials and are driven vertically by motors or cylinders. While this method solves the positioning problem to some extent, its reliance on a "rigid contact" and "active drive" design philosophy has revealed numerous drawbacks in practical applications.

[0004] The existing operating methods have three main problems: First, the "etching dead zone" and "yield killer" issues. Because the locating posts must maintain physical contact with the wafer edge for support, the contact point forms a hydrodynamic "stagnant point." Etching fluid or gas cannot effectively penetrate below the contact surface, preventing complete removal of the sealing film and resulting in etching residue caused by physical obstruction. Under high-precision inspection, these residues are often misjudged as cracks or chips, leading to yield loss. Second, the risks of "mechanical damage" and "particle contamination." The wafer edge is the weakest area in terms of mechanical strength. During frequent lifting and lowering movements, the rigid locating posts are highly susceptible to stress damage from minor vibrations or alignment errors, inducing microcrack propagation. Simultaneously, the complex lifting and lowering transmission mechanism, operating in an acidic corrosive environment for extended periods, generates wear particles that become a fatal source of contamination. Finally, there are the issues of "high maintenance costs" and "insufficient safety." Traditional mechanisms rely on precisely fitted moving parts, which have a very short lifespan (usually only 3 months) in hydrofluoric acid mist environments, and frequent downtime for maintenance significantly increases operation and maintenance costs. Summary of the Invention

[0005] The main purpose of this disclosure is to provide a wafer edge etching device and method based on gravity adaptive positioning. Through innovative passive mechanical structure and fluid dynamics design, it fundamentally solves the problems of etching dead angles, mechanical damage and insufficient safety in the prior art.

[0006] To achieve the above objectives, this disclosure provides a wafer edge etching apparatus based on gravity adaptive positioning, comprising: Inferior chamber; An upper chamber, located above the lower chamber, is capable of opening and closing relative to the lower chamber to form a closed etching environment; Multiple limit mechanisms; Each of the limiting mechanisms includes a rotating shaft and an L-shaped swing arm that rotates around the rotating shaft. The L-shaped swing arm is configured such that, in a first state where no wafer is placed, the L-shaped swing arm remains in an outwardly open position under the action of its own gravitational torque, thereby forming a channel for placing the wafer. The L-shaped swing arm is also configured such that, when the wafer is placed in the lower chamber and comes into contact with the L-shaped swing arm, the L-shaped swing arm rotates around the rotating shaft to a second state under the action of the wafer's own gravity, and the inner surface of the L-shaped swing arm flexibly limits and centers the edge of the wafer.

[0007] Furthermore, this disclosure also relates to a wafer edge etching method based on gravity adaptive positioning, the method being performed using the apparatus described above, the method comprising: The upper chamber is separated from the lower chamber, and the L-shaped swing arm is kept in the first outward opening state by utilizing the gravity of the limiting mechanism itself. The wafer is brought into contact with and pressed by its own gravity, driving the L-shaped swing arm to rotate around the axis to the second state. At the same time, the wafer is automatically pushed to the centering position by the coordinated action of the multiple limiting mechanisms. After etching is completed, the wafer is lifted, so that the L-shaped swing arm is freed from the pressure of the wafer's gravity and automatically returns to the first state under its own gravity.

[0008] This disclosure fundamentally changes the driving method and constraint mechanism of the wafer edge etching device by adopting a gravity-driven L-shaped swing arm structure, thereby triggering a series of progressive technical effects. First, since the L-shaped swing arm relies on its own gravitational torque to keep it open in the first state, forming a spacious channel for wafer placement, and in the second state it is driven by the wafer's own gravity to rotate and achieve limiting, this design replaces the motor, cylinder and its associated sensing, control and transmission chain system in the traditional solution with constant gravitational potential energy. Therefore, the active driving components are completely eliminated, the system complexity is reduced by orders of magnitude, thereby significantly reducing electrical failure points and sources of motion wear, significantly improving equipment reliability, and simplifying the chamber sealing design. Secondly, because the multiple limiting mechanisms are arranged circumferentially and symmetrically, each L-shaped swing arm is synchronously driven by the gravity of the same wafer. When the wafer descends and contacts the inner side of each swing arm, gravity is simultaneously decomposed into the reverse torque that drives each swing arm to rotate and the horizontal thrust on the wafer. Therefore, the rotation angle of each swing arm automatically adapts to the actual offset of the wafer. The swing arm on the offset side is compressed deeper and has a greater thrust, while the opposite side is the opposite. This forms a negative feedback mechanical closed loop between multiple contact points, continuously pushing the wafer to the lowest energy state of force balance. Ultimately, the geometric center of the wafer automatically coincides with the theoretical center determined by the mechanism. The alignment accuracy depends only on the consistency of the torque design of each swing arm and is not affected by sensor drift or control delay. Furthermore, because the L-shaped swing arm uses its inner surface rather than a rigid cylindrical surface to contact the wafer edge, and the limiting force originates from the wafer's gravity rather than a forced clamping force, the contact stress is flexibly dispersed, avoiding stress concentration in hard materials. Since the contact force adaptively adjusts with the magnitude of gravity, over-constraint is avoided. This creates an elastic support rather than rigid clamping in the most vulnerable chamfered area of ​​the wafer edge, fundamentally eliminating the induction of microcracks and particle friction. Simultaneously, because the swing arm opens outwards in the first state to form an unobstructed channel, there is no scraping between the wafer edge and the mechanism when the wafer is inserted. In the second state, only the inner surface lightly touches the wafer edge in a point contact mode. The etching medium can flow around the contact point and quickly re-adhere behind it. Boundary layer theory indicates that this point contact has extremely weak interference with the flow field, ultimately completely eliminating the "shadow effect" of traditional limiting pillars, and the edge etching residue rate approaches zero. Furthermore, after etching is completed, the method lifts the wafer to remove the gravitational pressure from the L-shaped swing arm. The swing arm then automatically resets to the first state under its own gravitational torque. The reset process does not require additional action commands or actuators and is seamlessly connected with the wafer pick-and-place action, thereby eliminating the independent steps such as lifting and lowering the limit column in the traditional solution. This shortens the single process cycle and correspondingly increases the equipment capacity and utilization rate. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of the main structure of the gravity-adaptive positioning wafer edge etching apparatus provided in this disclosure, showing the etching environment and wafer position consisting of an upper chamber and a lower chamber.

[0010] Figure 2 This is a schematic diagram of the working principle of the L-shaped limiting mechanism in the first state (without a wafer placed), showing the state in which the L-shaped swing arm opens outward under its own gravity torque to form a loading channel.

[0011] Figure 3 This is a schematic diagram of the working principle of the L-shaped limiting mechanism in the second state (after placing the wafer), showing the contact between the wafer and the guide ramp inside the limiting arm during the wafer's descent.

[0012] Figure 4 This is a top view schematic diagram of the arrangement of the limiting mechanisms, showing the layout of the four limiting mechanisms located at 45°, 135°, 225° and 315° azimuth angles on the wafer cleavage plane.

[0013] Figure 5 This is a schematic diagram of a closed-loop system for adjusting the etching width, showing the effect of a first closed-loop and a second closed-loop with different radial dimensions on the etching width adjustment.

[0014] Figure 6 This is a schematic flowchart of the wafer edge etching method based on gravity adaptive positioning provided in this disclosure. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description is provided in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of this disclosure.

[0016] Before delving into the specific structure of this disclosure, it is necessary to first describe the process environment and design in which this disclosure is situated. Semiconductor manufacturing equipment, especially equipment involving wet etching or dry plasma etching, faces extreme physicochemical challenges. The equipment not only needs to withstand long-term erosion from highly corrosive media such as hydrofluoric acid (HF) and nitric acid (HNO3), but also must control the wafer position with micron-level precision. Furthermore, due to the increasing wafer size (from 200mm to 300mm), its weight, brittleness, and dynamic behavior under high-speed rotation or airflow impact become increasingly complex. Traditional design approaches often tend towards "confrontation," that is, forcibly fixing the wafer by increasing the rigidity of the mechanical structure, increasing motor power, and using harder materials. However, this "head-on" strategy is precisely the root cause of mechanical damage and particulate contamination at the wafer edges. This disclosure takes a completely different approach, utilizing the most constant and reliable force—gravity—to replace complex electrical drives, achieving adaptive wafer fixation through flexible torque balance. This design not only simplifies the structure but also eliminates the physical root cause of defects in principle.

[0017] See Figure 1 The wafer edge etching apparatus based on gravity adaptive limiting provided in this disclosure comprises an etching environment consisting of an upper chamber 100 and a lower chamber 200. The lower chamber 200 typically serves as a fixed base, and its material is selected from specially corrosion-resistant aluminum alloy (surface hard anodized or nickel-plated) or high-purity stainless steel to ensure the structural stability and corrosion resistance of the apparatus. In the edge etching process, in order to expose the area to be etched at the wafer edge (typically a range of 1mm-3mm inward from the edge), the edge of the wafer 10 needs to be exposed, and in the initial placement stage, the wafer center may have a deviation. How to eliminate the deviation at the wafer center under these conditions without damaging its fragile edges is the key problem to be solved by the core mechanism of this disclosure—the L-shaped limiting mechanism.

[0018] See Figure 2 and Figure 3 The L-shaped limiting mechanism 300 is the core of this disclosure. Furthermore, Figure 3The area filled by the cross-sectional lines on the surface of wafer 10 schematically shows the layer to be etched, and the area filled by dots schematically shows the etching medium in the etching environment. Unlike the vertically lifting cylinder in the prior art, the limiting mechanism 300 of this disclosure adopts a rotating structure based on the lever principle. Specifically, each limiting mechanism 300 includes a horizontal rotating shaft 310 fixed on the base of the lower chamber 200, and an L-shaped swing arm that rotates freely around the rotating shaft 310. This L-shaped swing arm is geometrically composed of two parts: a counterweight arm 301 located outside the rotating shaft 310, and a limiting arm 302 located inside the rotating shaft 310. The connection between the two is provided with a shaft hole, which fits onto the rotating shaft 310. The rotating shaft 310 is preferably made of high-purity alumina ceramic or silicon carbide. These two materials are not only extremely hard and wear-resistant, but also have excellent inertness to acidic environments, which can prevent metal particle contamination during rotation. The L-shaped swing arm itself, or at least the part of the limiting arm 302 that contacts the wafer, is made of polytetrafluoroethylene (PTFE), commonly known as Teflon. The choice of PTFE is not arbitrary, but based on the following material science considerations: First, PTFE has almost perfect chemical corrosion resistance, capable of withstanding long-term erosion from mixed acid mists of HF and HNO3 without swelling or degradation; second, PTFE has extremely low surface energy and a coefficient of friction (dynamic coefficient of friction can be as low as 0.04), meaning that when it contacts the wafer edge and undergoes relative sliding (self-alignment process), the frictional resistance is minimal and friction particles are not easily generated; finally, and most importantly, PTFE's hardness is much lower than that of single-crystal silicon. This soft material undergoes slight elastic deformation upon contact, thereby greatly dispersing contact stress and acting as a buffer, fundamentally eliminating the risk of stress concentration and microcracks caused by hard limiting pillars.

[0019] The dynamic behavior of the L-shaped limit mechanism 300 is based on a precise torque balance design. To achieve "passive drive" and "intelligent opening and closing," the design mass and lever arm length of the counterweight arm 301 have undergone rigorous calculations. We define the pivot 310 as the fulcrum. (As in...) Figure 2As shown, in the first state without external force (i.e., no wafer is placed), the gravitational torque generated by the counterweight arm 301 is greater than that generated by the limiting arm 302. Under the action of this net torque, the L-shaped swing arm will naturally rotate outward around the pivot 310 until the bottom of the counterweight arm 301 touches the set limiting block (not shown) or the lower chamber base. At this time, the limiting arm 302 opens outward, presenting an "upward L-shaped" posture. In this state, the diameter of the envelope circle formed by the tops of the four limiting arms 302 is larger than the diameter of the wafer 10 (for example, for a 300mm wafer, the diameter of the envelope circle can be designed to be 310mm). This forms a spacious, unobstructed loading channel. The external mechanical transfer arm can place the wafer 10 vertically downward or place it on the raised central pin (not shown), and throughout the process, the edge of the wafer will never laterally scrape against the limiting mechanism. This completely avoids the "card" or "fragment" accidents caused by asynchronous lifting of the limit column or misplacement of the wafer in traditional equipment.

[0020] When wafer 10 is released and begins to descend (e.g., driven by the center pin), the core mechanism of this disclosure—gravity-adaptive centering—comes into play. Figure 3 As shown, the inner side of the limiting arm 302 has a guide ramp 302a with a specially designed curvature. When the wafer 10 descends to a certain height, its outermost edge will first contact the guide ramp 302a in its open state. At this time, the mechanical balance within the system is broken. The wafer 10, as a mass (a 300mm wafer weighs approximately 125 grams), exerts its gravity on the guide ramp 302a through the contact point. The force exerted by the wafer 10 on the guide ramp 302a can be decomposed into a vertically downward component and a horizontally outward component. The vertical component is applied to the limiting arm 302, generating a reverse torque. Because the design ensures that the reverse torque is much greater than the restoring torque of the counterweight arm, the L-shaped swing arm is forced to rotate inward around the pivot 310. This rotational motion has two results: first, the limiting arm 302 gradually changes from an "upward L-shape" to a "downward L-shape"; second, the guide ramp 302a exerts a horizontally inward thrust on the edge of the wafer.

[0021] Because the device has four symmetrical limiting mechanisms 300 arranged circumferentially, these four horizontal inward thrusts form a closed-loop negative feedback control system. Assuming the wafer 10 is placed biased to the left, the left limiting mechanism 300 will experience earlier and deeper pressure from the wafer, resulting in a larger reverse thrust; while the right mechanism experiences less force and a smaller thrust. This force imbalance drives the wafer to move to the right until the forces in the four directions reach equilibrium. At this point, the geometric center of the wafer perfectly coincides with the center determined by the four limiting mechanisms. This process is entirely automatic, requiring no sensors to detect position or any motors for servo adjustment. It utilizes the most fundamental principle of physics, the "principle of minimum energy"—the wafer can only reach a stable state of minimum potential energy in its lowest position (i.e., the center position, where all L-arms are pressed down equally). This passive alignment is not only extremely accurate (up to ±0.05mm) but also highly robust, and will not fail due to sensor drift or electrical interference.

[0022] When wafer 10 is fully seated and enters the etching process stage (second state), the contact state between the limiting arm 302 and the wafer edge is key to solving the "etching dead zone" problem in this disclosure. Traditional cylindrical limiting posts typically have line contact or even surface contact with the wafer edge (considering the deformation of the cylindrical surface). This tight physical contact blocks the fluid flow, leading to poor chemical displacement below the contact area and creating a "shadow effect." In contrast, the L-shaped limiting arm 302 of this disclosure, in its final equilibrium state, gently rests on the wafer edge solely due to gravity. Thanks to the design of the guide ramp 302a, the contact point is strictly limited to the outermost chamfered area of ​​the wafer edge or a very small point in the non-functional area. From a fluid dynamics perspective, this point contact has minimal interference with the flow field. Etching gas or liquid can smoothly bypass the contact point and flow across the upper and lower surfaces of the wafer edge. Boundary layer theory tells us that when fluid bypasses a small obstacle, it quickly adheres behind it, thus ensuring a sufficient supply of reactants to the area behind the contact point. Experimental data show that by using the flexible point contact scheme disclosed herein, the etching residue rate at the wafer edge is reduced to almost zero, completely eliminating false defects in subsequent inspections.

[0023] Furthermore, the spatial layout of the L-shaped limiting mechanism 300 is also one of the important innovations of this disclosure. For example... Figure 4As shown, four limiting mechanisms 300 are respectively arranged at 45°, 135°, 225° and 315° azimuth angles of the cleavage plane 11 of the wafer 10 at the center position. This arrangement is not arbitrary, but based on a deep understanding of the crystallographic properties of single-crystal silicon. For the (100) crystal orientation wafers most commonly used in the semiconductor industry, its cleavage plane (i.e. the crystal plane most prone to fracture) is usually located in the {111} plane family, which corresponds to a direction at a specific angle to the main flat edge or notch on the plane projection of the (100) wafer. Traditional layouts are often based on considerations of avoiding robotic arms or other components, without fully taking into account the mechanical anisotropy of the wafer. If the force direction of the limiting mechanism happens to coincide with the cleavage plane, the wafer is very likely to fracture brittlely along the cleavage plane when subjected to thermal stress or mechanical impact. The 45° symmetrical layout disclosed herein avoids the stress-sensitive regions of the main cleavage planes through geometric calculations, ensuring that the externally applied clamping force (even the flexible gravitational component) is distributed in the direction of higher wafer mechanical strength, thereby significantly reducing the risk of wafer breakage. Simultaneously, from a fluid dynamics perspective, the 45° orthogonal layout has higher rotational symmetry, which helps to form a more uniform swirling flow field within the cavity. In rotary etching processes, the uniformity of the gas or liquid flow directly determines the azimuth uniformity of the etching rate. The optimized layout reduces turbulence and vortex dead zones in the flow field, resulting in a highly consistent etching width across the entire wafer.

[0024] Having addressed the issues of mechanical positioning and etching dead zones, this disclosure further focuses on the adjustability and flexibility of the process. Edge etching processes are not static; different chip products and different subsequent packaging requirements necessitate different definitions of the edge exclusion width (EEW) (e.g., 1mm, 1.5mm, or 2mm). Traditional equipment adjustment of the etching cycle (CD) typically relies on adjusting process parameters such as etching time, flow rate, or pressure, which often has far-reaching consequences and requires lengthy verification. This disclosure introduces a purely physical adjustment mechanism—a closed-loop 400. Figure 5 As shown, the herring ring 400 is removable and replaceable. We physically change the spacing between the wafer edge and the outer periphery of the herring ring 400 by providing a series of herring ring kits with different radial dimensions, thereby adjusting the coverage of the etching medium (in conjunction with...). Figure 3 (Easy to understand), thereby adjusting the edge etching width. Specifically, when a sealing ring 400 with a first radial dimension (e.g., a larger radial dimension) is installed ( Figure 5 (shown by the solid line in the middle), the flow channel is narrower, resulting in a smaller etch width D1; while when replaced with a closed ring 400 having a second radial dimension (e.g., a smaller radial dimension) ( Figure 5(As shown by the dashed line), the flow channel widens, resulting in a larger etching width D2. This method of adjusting process parameters by changing hardware offers extremely high determinism and repeatability. Once a suitable closed-loop 400 is selected, the etching width value is "locked" by the physical structure and will not fluctuate with the environment as easily as process parameters, greatly improving process stability.

[0025] Beyond its core process performance, this disclosure also features groundbreaking designs in terms of equipment safety. Etching media used in semiconductor manufacturing, such as hydrofluoric acid, are highly toxic and permeable. Traditional sealing methods (O-rings) may age, harden, or corrode after prolonged exposure to acidic gases, leading to minute leaks. These leaks are often difficult to detect in time by conventional indoor gas detectors, only triggering an alarm when a certain concentration has accumulated, by which time equipment corrosion or a threat to personnel has often already occurred. (See also: [link to relevant documentation]) Figure 3 This disclosure introduces a zone safety module 500 at the closed boundary between the upper chamber 100 and the lower chamber 200. The zone safety module 500 includes an annular groove 502 located outside the main sealing ring. The annular groove 502 is connected to the plant's acid exhaust system and is maintained at a slight negative pressure (e.g., -100 Pa to -300 Pa) throughout the process. This negative pressure zone serves two purposes: first, it acts as a "dynamic barrier"—if a micro-leak occurs in the main sealing ring, the leaking high-pressure process gas will be directly captured and drawn away by the negative pressure of the annular groove 502, preventing it from leaking into the outside atmosphere. Second, it acts as an "online monitoring station." The zone safety module 500 also includes a highly sensitive pressure sensor 501 for monitoring the pressure within the annular groove 502. Under normal conditions, the pressure is maintained at a set negative pressure baseline. If the main seal fails, allowing a large influx of process gas, or if external air enters due to damage to the outer seal, pressure sensor 501 will immediately detect the drastic pressure fluctuation. Upon receiving the signal, the control system will immediately trigger hardware interlocks: instantly cutting off the process gas supply valve, stopping the RF power supply (in the case of dry etching), and activating the auxiliary exhaust fan at full power. This proactive defense mechanism eliminates safety hazards in their early stages, fully meeting and even exceeding the requirements of semiconductor equipment environmental health and safety standards and exhaust ventilation standards.

[0026] To ensure the long-term reliable operation of the device described in this disclosure, a maintenance strategy is an indispensable part of the design. Traditional active limit mechanisms contain complex moving parts such as motors, lead screws, slide rails, and cylinders, which are prone to failure in acidic corrosive environments. Particles are a major enemy of semiconductor processes, and mechanical friction is the primary source of particles. The L-shaped limit mechanism 300 of this disclosure has only one low-speed rotating friction pair in the entire system, the rotating shaft 310. Due to the use of PTFE and ceramic pairing, the coefficient of friction is extremely low and it has self-lubricating properties, eliminating the need for any lubricating oil or grease (which is absolutely prohibited in vacuum chambers). This "maintenance-free" or "low-maintenance" design concept significantly extends the theoretical lifespan of the limit mechanism from 3 months in traditional solutions to more than 1 year. More importantly, due to its simple structure (consisting of only two or three parts) and the absence of electrical calibration, replacement and cleaning become exceptionally simple. Technicians can complete the disassembly and replacement of the L-shaped arm in just a few minutes, greatly shortening the average repair time of the equipment and improving its uptime.

[0027] Accordingly, see Figure 6 This disclosure also provides a wafer edge etching method based on gravity adaptive positioning, which is performed using the apparatus according to the foregoing embodiments, and includes: S601: Separate the upper chamber from the lower chamber, and use the gravity of the limiting mechanism itself to keep the L-shaped swing arm in the first outward opening state; S602: The wafer is brought into contact with and pressed by its own gravity, and the L-shaped swing arm is driven to rotate around the pivot to the second state. At the same time, the wafer is automatically pushed to the centering position by the synergistic effect of the multiple limiting mechanisms. S603: After etching is completed, the wafer is lifted up, so that the L-shaped swing arm is freed from the pressure of the wafer's gravity and automatically resets to the first state under its own gravity.

[0028] Next, we will describe in detail the workflow of the apparatus and method described in this disclosure through a complete process cycle. This process not only covers mechanical actions but also integrates the timing coordination of fluid and chemical reactions.

[0029] Before the process begins, the upper chamber 100 is in the high-open position. The limiting mechanism 300 in the lower chamber 200 is in the first state. Under the action of gravity, the four L-shaped swing arms open outward, forming a spacious and unobstructed loading channel. At this time, the external robotic arm holds a wafer 10 to be processed (e.g., 300mm, with a CVD-deposited silicon dioxide film on the edge) and extends it into the upper chamber. The device's ejector pin rises to receive the wafer 10. The robotic arm then retracts. At this time, the area safety module 500 is in standby monitoring mode.

[0030] The ejector pin slowly lowers wafer 10. When the edge of the wafer contacts the guide ramp 302a of the limiting mechanism 300, the gravitational potential energy of wafer 10 begins to convert into mechanical driving energy. The four L-shaped swing arms synchronously rotate inward under the pressure of the wafer's gravity. If there is a deviation in the wafer's placement (e.g., biased towards 315°), the swing arm at 315° will experience the force first and be stronger, generating a reverse thrust that pushes the wafer towards 135° until the forces in all four directions are balanced. Finally, wafer 10 falls smoothly, now in a centered state. The limiting arm 302 remains in a "downward L-shaped" position, flexibly holding the wafer edge. The entire process is smooth and impact-free, avoiding excessive instantaneous stress.

[0031] The upper chamber 100 descends and presses against the lower chamber 200. The sealing ring is compressed into place. At this time, the annular groove 502 of the safety module 500 in the control system's control area establishes a negative pressure barrier, and the pressure sensor 501 begins real-time monitoring. Simultaneously, nitrogen gas is introduced into the main reaction chamber for purging, replacing the air and establishing the micro-positive pressure or vacuum environment required for the process.

[0032] According to the predetermined process formula, the etching medium is introduced into the chamber.

[0033] For wet etching: Wafer 10 rotates at high speed (e.g., 500-1500 RPM). The nozzle sprays the pre-mixed etching solution onto the wafer edge. Under centrifugal force, the solution spreads towards the edge. At this time, the sealed ring 400 (pre-selected size) precisely controls the width of the liquid flow, ensuring the etching width meets requirements. The point contact design of the limiting arm 302 allows the solution to clean the contact points without obstruction, ensuring no dead zones.

[0034] For dry etching: a fluorine-containing process gas is introduced into the chamber, and radio frequency energy is applied to excite the plasma. A closed loop 400 controls the range of ion bombardment. The limiting arm 302 is made of a material resistant to plasma bombardment and will not introduce metallic impurities.

[0035] After the etching reaction is complete, the etching medium is cut off. For wet processes, deionized water is sprayed to clean the edges and remove residual acid, followed by swirl drying using high-purity nitrogen. During this process, the wafer continues to rotate, and the L-shaped limiting mechanism 300 relies on the wafer's gravity to maintain stability, resist airflow disturbances, and prevent the wafer from flying out or shifting.

[0036] The upper chamber 100 rises. The central ejector pin lifts wafer 10. As the wafer rises, the pressure it exerts on the limiting arm 302 gradually disappears. Under the torque of the counterweight arm 301, the L-shaped swing arm automatically flips outward, returning to its initial "upward L-shaped" position. The robotic arm reaches in to remove the processed wafer and inserts the next wafer. The entire cycle is smooth and efficient, with no unnecessary mechanical waiting time.

[0037] In summary, the technical solution provided in this disclosure, through a profound application of fundamental physical principles and meticulous refinement of process details, successfully constructs a wafer edge etching system integrating high precision, high yield, high reliability, and high security. It not only solves current industry pain points but also provides a highly valuable reference paradigm for the design of future larger-size and more advanced semiconductor devices. Utilizing gravity—a cost-free and indestructible energy source—in conjunction with advanced materials and fluid dynamics design, this disclosure demonstrates the enormous potential of minimalist engineering design in solving complex manufacturing problems.

[0038] It should be noted that the technical solutions described in this disclosure can be combined arbitrarily as long as they do not 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 wafer edge etching apparatus based on gravity adaptive positioning, comprising: Inferior chamber; An upper chamber, located above the lower chamber, is capable of opening and closing relative to the lower chamber to form a closed etching environment; Multiple limit mechanisms; The feature is that each of the limiting mechanisms includes a rotating shaft and an L-shaped swing arm that rotates around the rotating shaft. The L-shaped swing arm is configured such that, in a first state where no wafer is placed, the L-shaped swing arm remains in an outwardly open position under the action of its own gravitational torque, thereby forming a channel for placing the wafer. The L-shaped swing arm is also configured such that, when the wafer is placed in the lower chamber and comes into contact with the L-shaped swing arm, the L-shaped swing arm rotates around the rotating shaft to a second state under the action of the wafer's own gravity, and the inner surface of the L-shaped swing arm flexibly limits and centers the edge of the wafer.

2. The wafer edge etching apparatus based on gravity adaptive positioning according to claim 1, characterized in that, The L-shaped swing arm includes a counterweight arm connected to one side of the pivot and a limiting arm connected to the other side of the pivot.

3. The wafer edge etching apparatus based on gravity adaptive positioning according to claim 2, characterized in that, The inner side of the limiting arm is provided with a guide ramp, which is configured to contact the chamfered area of ​​the wafer edge during the wafer descent process, and convert the gravitational component of the wafer into a torque that pushes the L-shaped swing arm to rotate, while converting the reaction force generated by the limiting arm into a horizontal component that pushes the wafer to move toward the centering position.

4. The wafer edge etching apparatus based on gravity adaptive positioning according to claim 3, characterized in that, At least the portion of the limiting arm that contacts the wafer is made of polytetrafluoroethylene.

5. The wafer edge etching apparatus based on gravity adaptive positioning according to claim 1, characterized in that, The plurality of limiting mechanisms are four in number and are respectively arranged at 45°, 135°, 225° and 315° azimuth angles on the cleavage surface of the wafer at the center position, so as to avoid the stress-sensitive area of ​​the cleavage surface of the wafer and promote the uniform distribution of the swirling flow field in the etching environment.

6. The wafer edge etching apparatus based on gravity adaptive positioning according to claim 1, characterized in that, The device also includes a regional safety module located at the closed interface between the upper chamber and the lower chamber. The regional safety module includes an annular groove, an auxiliary exhaust channel communicating with the annular groove, and a pressure sensor for monitoring the pressure within the annular groove. The regional safety module is configured to maintain a negative pressure state relative to the external environment during the etching process to capture potential leaked gases.

7. The wafer edge etching apparatus based on gravity adaptive positioning according to claim 1, characterized in that, The device also includes a detachably mounted hermetical ring selected from a set of hermetical rings with different radial dimensions to adjust the coverage of the etching medium by physically changing the distance between the wafer edge and the outer periphery of the hermetical ring, thereby adjusting the edge etching width.

8. The wafer edge etching apparatus based on gravity adaptive positioning according to claim 1, characterized in that, In the second state, the guide ramp of the limiting arm makes only point contact with the wafer edge, and the point contact is located in the chamfered area of ​​the wafer edge, so as to allow the etching medium fluid to flow around the contact point and thus eliminate etching dead corners.

9. The wafer edge etching apparatus based on gravity adaptive positioning according to claim 1, characterized in that, The device is configured for wet etching processes or dry plasma etching processes.

10. A wafer edge etching method based on gravity-adaptive positioning, characterized in that, The method is performed using the apparatus according to any one of claims 1 to 9, the method comprising: The upper chamber is separated from the lower chamber, and the L-shaped swing arm is kept in the first outward opening state by utilizing the gravity of the limiting mechanism itself. The wafer is brought into contact with and pressed by its own gravity, driving the L-shaped swing arm to rotate around the axis to the second state. At the same time, the wafer is automatically pushed to the centering position by the coordinated action of the multiple limiting mechanisms. After etching is completed, the wafer is lifted, so that the L-shaped swing arm is freed from the pressure of the wafer's gravity and automatically returns to the first state under its own gravity.

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