Semi-automatic wafer cleaning machine and wafer cleaning method

Abstract

This invention relates to the field of semiconductor cleaning equipment technology, and discloses a semi-automatic wafer cleaning machine and wafer cleaning method, including a cabinet. A working top plate is fixedly mounted on the top of the cabinet, a splash guard is fixedly mounted on the top of the working top plate, an interactive panel is fixedly mounted on the top of the splash guard, a support mechanism is fixedly mounted at the center of the working top plate, and a wafer tray is fixedly mounted on the top of the support mechanism. The water outlet group sprays cleaning fluid upwards at a preset flow rate, generating upward hydrodynamic pressure on the back of the wafer. Simultaneously, the water return group naturally drains the fluid, creating a negative pressure. The combined effect suspends the wafer above the supporting chassis, forming a continuous transverse flow micro-circulation field. Desorbed particulate contaminants are promptly carried away by the liquid flow and discharged through the water return group, avoiding blind spots and particle redeposition problems caused by solid contact, significantly improving the back-side cleaning effect.

Description

Technical Field

[0001] This invention relates to the field of semiconductor cleaning equipment technology, specifically to a semi-automatic wafer cleaning machine and a wafer cleaning method. Background Technology

[0002] In semiconductor manufacturing processes, wafer cleaning is a critical step determining device yield and reliability. As process nodes continue to shrink, higher demands are placed on the efficiency of removing particulate contaminants from the back of the wafer and controlling wafer damage during the cleaning process. Existing semi-automatic wafer cleaning machines typically use a support chassis to hold the wafer, and a spray arm sprays cleaning fluid onto the front of the wafer, with the back of the wafer in direct contact with the upper surface of the support chassis. This cleaning method has the following technical drawbacks: the contact between the back of the wafer and the support chassis is solid, meaning that particulate contaminants on the back cannot be effectively carried away by the liquid flow, resulting in poor back-side cleaning performance; simultaneously, the mechanical stress generated by the solid contact can easily cause scratches or microcracks on the back of the wafer, affecting wafer quality. Summary of the Invention

[0003] The main objective of this application is to provide a semi-automatic wafer cleaning machine and wafer cleaning method to solve the technical problem in the prior art where the back side of the wafer is in contact with the solid of the supporting chassis, resulting in poor back side cleaning effect and easy damage to the wafer. It has the beneficial effect of achieving efficient cleaning of the back side of the wafer while avoiding mechanical damage to the wafer.

[0004] The present invention provides the following technical solution: a semi-automatic wafer cleaning machine, including a base cabinet, a working top plate fixedly mounted on the top of the base cabinet, a splash guard fixedly mounted on the top of the working top plate, an interactive panel fixedly mounted on the top of the splash guard, a support mechanism fixedly mounted on the top of the center of the working top plate, a wafer tray fixedly mounted on the top of the support mechanism, side motors fixedly mounted on both sides of the working top plate, and spray rocker arms fixedly mounted on the output ends of the side motors; The wafer tray includes a support base, the top of which has a surface groove, and the bottom of which has a plurality of liquid through holes evenly distributed in concentric annular areas. The liquid through holes are divided into a water outlet through hole group and a water return through hole group. A bottom liquid pipe is fixedly installed at the center of the bottom of the supporting chassis. The bottom liquid pipe is connected to several liquid through holes in the inner ring area to form an inner ring water outlet through hole group. An outer liquid pipe is fixedly installed on the outer wall of the bottom liquid pipe. The outer liquid pipe is connected to several liquid through holes in the middle ring area and the outer ring area in an intermittent manner to form a middle ring and outer ring water outlet through hole group. The remaining liquid through holes form a return water through hole group. The return water through hole group is connected to the external drainage passage, and the cleaning fluid is naturally discharged through the return water through hole group. The water outlet through-hole group and the water return through-hole group are alternately arranged on the upper surface of the support base, so that the wafer is suspended above the support base at a predetermined distance under the combined action of the upward dynamic pressure generated by the water outlet through-hole group and the drainage negative pressure formed by the water return through-hole group. A fluid support pad with a thickness of 0.5mm to 1.5mm is formed between the back side of the wafer and the upper surface of the support base. The cleaning liquid in the fluid support pad flows laterally between the water outlet through-hole group and the water return through-hole group to refresh the back cleaning liquid and carry away the desorbed particles. The outer wall of the supporting chassis is fixedly equipped with several protective shells along the circumference. A transmission module is fixedly equipped inside the protective shells. A cleaning chamber is opened in the inner cavity of the supporting chassis. The cleaning chamber coincides with several liquid through holes of the water outlet through hole group. A shielding slide is slidably sleeved inside the cleaning chamber. The shielding slide is engaged with the moving end of the transmission module. The effective flow area of ​​the water outlet through hole group is adjusted by moving the shielding slide in the cleaning chamber.

[0005] As a preferred embodiment of the present invention, a megasonic transducer array is embedded in the interior or lower surface of the substrate of the supporting chassis, the operating frequency of the megasonic transducer array is 0.8MHz to 1.2MHz, and the substrate material of the supporting chassis is quartz. The acoustic waves generated by the mega-sonic transducer array are conducted to the back side of the wafer via the supporting chassis substrate and the fluid support pad. The thickness δ of the fluid support pad satisfies the standing wave resonance condition δ=n×λ / 2, where λ is the wavelength of the acoustic waves in the cleaning fluid and n is a positive integer, so that a standing wave resonance is formed in the fluid support pad. The acoustic radiation force drives the particles on the back side of the wafer to migrate towards the acoustic pressure wave nodal surface and are discharged with the liquid flow of the return water through hole group.

[0006] As a preferred embodiment of the present invention, the shielding slider causes the water outlet direction to deviate from the axis of the liquid through-hole and generates a tangential velocity component parallel to the back side of the wafer. The tangential components of each shielding slider are in the same direction, so that the cleaning fluid generates a tangential impact torque in the same direction on the outer edge region of the back side of the wafer, driving the wafer to rotate around its central axis. The effective flow rate of the water outlet through-hole group is controlled by adjusting the movement of the shielding slider, thereby controlling the wafer rotation speed. The water outlet direction of the liquid through-holes in the inner ring region and the middle ring region remains vertical, only providing dynamic pressure for suspension support, and does not participate in rotation drive, thereby achieving decoupled independent control of suspension support force and rotation drive torque.

[0007] As a preferred embodiment of the present invention, the support mechanism includes a hollow shaft, a water-blocking baffle, and a connecting seat; The hollow shaft is rotatably inserted into the central through hole of the working top plate via a bearing. A liquid transmission channel is axially formed at the central axis of the hollow shaft, and the liquid transmission channel is connected to the bottom liquid pipe. The water-blocking baffle is a disc-shaped structure, which is fixedly assembled on the outer wall of the middle part of the hollow shaft. The bottom surface of the water-blocking baffle and the top surface of the working top plate form a seal to prevent the cleaning fluid from leaking downward from the gap between the hollow shaft and the working top plate. The connecting seat is a flange structure, fixedly assembled on the top of the water-blocking baffle, and rigidly connected to the bottom of the supporting chassis.

[0008] As a preferred technical solution of the present invention, the transmission module includes a drive motor, a signal control component, a screw, a limit guide rod, a moving nut, and a protective bracket; The drive motor is fixedly mounted on the inner wall of the protective housing, and the signal control component is fixedly mounted on the outer wall of the drive motor; the screw is coaxially fixedly mounted on the output end of the drive motor, and the limiting guide rod is arranged parallel to the screw; the middle part of the movable nut is threaded to the outer surface of the screw, and the side part of the movable nut is slidably sleeved on the limiting guide rod; the protective bracket is a U-shaped bracket, and the ends of the limiting guide rod and the screw are rotatably connected to the two ends of the protective bracket respectively; the driving end of the shielding slide is engaged and fixed with the movable nut.

[0009] As a preferred embodiment of the present invention, the drive motor is a micro stepper motor; the signal control component is a control board with an encoder, used to receive control signals and precisely control the rotation angle and speed of the drive motor.

[0010] As a preferred embodiment of the present invention, the shielding slide is made of polytetrafluoroethylene, and its thickness is matched with the height of the cleaning chamber with a small gap.

[0011] As a preferred embodiment of the present invention, the protective shell and the outer wall of the supporting chassis are detachably sealed together by means of a sealing ring and screws.

[0012] As a preferred embodiment of the present invention, the spray arm includes a cleaning nozzle and a cleaning pipe. The cleaning pipe is a hollow pipe, with one end connected to a liquid supply line and the other end fitted with the cleaning nozzle. Multiple cleaning nozzles at different angles are arranged side by side on the outer wall of the cleaning pipe.

[0013] The wafer cleaning method of a semi-automatic wafer cleaning machine includes the following steps: Step S1, Loading and Pre-stabilization: The operator places the wafer to be cleaned in the surface sink and selects the cleaning program through the interactive panel; the control unit starts the water outlet hole group, which sprays the cleaning fluid upward through the bottom liquid pipe and the outer liquid pipe at a preset flow rate. The return water hole group is connected to the external drainage channel for natural drainage, and a fluid support pad with a thickness of 0.5mm to 1.5mm is established between the back of the wafer and the upper surface of the support base, so that the wafer is suspended above the support base and has no solid contact with the upper surface of the support base. Step S2, Rotation Start: The control unit adjusts the shielding slide corresponding to the water outlet hole group in the outer ring area to the target position through the transmission module, so that the water outlet hole group in the outer ring generates a tangential impact torque, driving the wafer to rotate around the central axis to the target speed; the water outlet direction of the liquid holes in the inner ring area and the middle ring area remains vertical, only providing dynamic pressure for suspension support; Step S3, Chemical Cleaning: The megaacoustic transducer array is started at a working frequency of 0.8MHz to 1.2MHz. The acoustic waves are coupled to the back of the wafer through the supporting chassis substrate and the fluid support pad. The thickness δ of the fluid support pad is maintained at the standing wave resonance condition δ=n×λ / 2. The side motor drives the spray arm to swing above the wafer, and the cleaning nozzle sprays chemical cleaning solution onto the front of the wafer. Step S4, deionized water rinsing and unloading: The spray arm switches to deionized water to rinse the front side of the wafer; after cleaning, the water supply through the outlet is gradually closed, and the wafer falls back smoothly into the surface sink under gravity, and the operator takes out the wafer.

[0014] The present invention has the following beneficial effects: The semi-automatic wafer cleaning machine and wafer cleaning method involve spraying cleaning fluid upwards at a preset flow rate through the water outlet through-hole group, generating upward hydrodynamic pressure on the back of the wafer. At the same time, the return water through-hole group naturally drains the liquid, forming a negative pressure for drainage. The two work together to suspend the wafer above the support base, forming a fluid support pad of 0.5mm to 1.5mm between the back of the wafer and the upper surface of the support base. In this fluid support pad, the cleaning fluid is sprayed out from the water outlet hole group and flows laterally to the adjacent water return hole group before being discharged, forming a micro-circulation flow field with continuous lateral flow. This ensures that the back side of the wafer is always in contact with fresh cleaning fluid, and the desorbed particulate contaminants are carried away by the liquid flow in time and discharged through the water return hole group. This avoids the back cleaning blind zone and particle redeposition problems caused by solid contact, and significantly improves the back cleaning effect. At the same time, there is no solid contact between the wafer and the supporting chassis, which eliminates the mechanical stress caused by solid contact and avoids the generation of scratches or microcracks on the back of the wafer. In addition, the fluid support pad has elastic potential well characteristics: when the wafer is biased towards the support base due to external disturbance, the gap narrows, resulting in an increase in the outflow dynamic pressure, which automatically pushes the wafer back to the equilibrium position; when the wafer deviates from the support base, the gap widens, resulting in a relatively stronger drainage negative pressure, which automatically pulls the wafer back to the equilibrium position. Stable suspension can be maintained without active closed-loop control, which further ensures the safety of the wafer during the cleaning process. Attached Figure Description

[0015] Figure 1 This is a three-dimensional structural diagram of the present invention; Figure 2 This is a schematic diagram of the installation position of the top plate of the present invention; Figure 3 This is a schematic diagram showing the installation position of the support mechanism of the present invention; Figure 4 This is a schematic diagram of the spray rocker arm structure of the present invention; Figure 5 This is a schematic diagram of the side motor structure of the present invention; Figure 6 This is a schematic diagram of the support mechanism structure of the present invention; Figure 7 This is a schematic diagram of the wafer tray mounting position according to the present invention; Figure 8 This is a schematic diagram of the liquid through-hole structure of the present invention; Figure 9 This is a schematic diagram of the outer liquid tube structure of the present invention; Figure 10 This is a schematic diagram of the cleaning chamber structure of the present invention; Figure 11 This is a schematic diagram of the transmission module structure of the present invention.

[0016] In the diagram: 1. Base cabinet; 2. Splash guard frame; 3. Interaction panel; 4. Operating top plate; 5. Support mechanism; 6. Wafer tray; 7. Side motor; 8. Sprayer arm; 51. Hollow shaft; 52. Water-blocking baffle; 53. Connecting seat; 61. Support chassis; 62. Surface recess; 63. Liquid passage; 64. Protective housing; 65. Bottom liquid pipe; 66. Outer liquid pipe; 67. Cleaning chamber; 68. Shielding slide; 69. Transmission module; 691. Drive motor; 692. Signal control component; 693. Limiting guide rod; 694. Lead screw; 695. Moving nut; 696. Protective bracket. Detailed Implementation

[0017] 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 embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] Figure 1 A schematic structural diagram of a semi-automatic wafer cleaning machine is shown. (For example...) Figure 1 As shown in the embodiment of this application, a semi-automatic wafer cleaning machine is provided. The semi-automatic wafer cleaning machine includes a base cabinet 1, a working top plate 4, a splash guard 2, an interactive panel 3, a support mechanism 5, a wafer tray 6, a side motor 7, and a spray rocker arm 8.

[0019] Specifically, the top plate 4 is fixedly assembled to the top of the cabinet 1 by fasteners such as bolts. The cabinet 1 integrates a liquid supply system, a control system and a power module (not shown in the figure). The liquid supply system is used to provide pressurized chemical cleaning fluid and deionized water for the cleaning process. The control system includes control units such as microprocessors, which are used to execute preset cleaning programs and coordinate the work of various components.

[0020] The splash guard 2 is fixedly mounted on the top of the working top plate 4, forming a four-sided enclosed cleaning work area to prevent cleaning fluid from splashing outwards during the cleaning process. The interactive panel 3 is fixedly mounted on the top of the splash guard 2, allowing operators to set cleaning parameters and control the start and stop of the equipment.

[0021] The support mechanism 5 is fixedly mounted on the top of the working top plate 4 at its center, and is used to support the wafer tray 6. The wafer tray 6 is fixedly mounted on the top of the support mechanism 5, serving as the core component for carrying the wafers to be cleaned. Two side motors 7 are fixedly mounted on the bottom sides of the working top plate 4, respectively, with the top output shaft of each side motor 7 extending upward from the working top plate 4. The base of the spray arm 8 is fixedly mounted on the top output shaft of the side motor 7, and its end is equipped with a cleaning nozzle (not shown). During operation, the side motors 7 on both sides drive the spray arm 8 to swing back and forth above the wafer according to the preset program of the control system. The cleaning nozzle at the end of the spray arm 8 evenly sprays the cleaning solution or deionized water onto the upper surface of the wafer, completing the cleaning work on the front side of the wafer.

[0022] The wafer tray 6 includes a support base 61. The support base 61 has a disc-shaped structure, with a recessed central area at its top forming a surface groove 62, which is used to accommodate and position the wafer. The bottom of the surface groove 62 has multiple liquid through holes 63 evenly distributed in multiple concentric annular areas. The liquid through holes 63 are divided into groups of outflow through holes and groups of return through holes with different functions.

[0023] A bottom liquid pipe 65 is integrally formed at the center of the bottom of the support chassis 61. This bottom liquid pipe 65 is directly connected to multiple liquid through holes 63 located in the inner ring region, forming an inner ring water outlet through hole group. An outer liquid pipe 66 is fixedly fitted to the outer wall of the bottom liquid pipe 65. The outer liquid pipe 66 is connected to a portion of the liquid through holes 63 distributed in the middle and outer ring regions in an intermittent manner, forming middle and outer ring water outlet through hole groups. Among all the liquid through holes 63, the remaining liquid through holes 63, except those forming the water outlet through hole group, form a return water through hole group. The return water through hole group is connected to a drainage passage provided inside or outside the support chassis 61, and the cleaning fluid can be naturally discharged through the return water through hole group under the action of gravity or pressure difference.

[0024] The water outlet and return through-hole groups are arranged alternately on the upper surface of the support chassis 61. During the cleaning process, the liquid supply system connecting the bottom liquid pipe 65 and the outer liquid pipe 66 pumps the cleaning fluid upward at a preset flow rate. The cleaning fluid is sprayed upward from the water outlet through-hole group, generating upward hydrodynamic pressure on the back side of the wafer. At the same time, the return through-hole group, due to the discharge of liquid, forms a relatively low-pressure area near its orifice, generating downward fluid suction on the back side of the wafer. Under the combined action of these two forces, the wafer overcomes its own gravity and suspends itself at a predetermined distance above the support chassis 61. At this time, a fluid support pad with a thickness of 0.5 mm to 1.5 mm is formed between the back side of the wafer and the upper surface of the support chassis 61.

[0025] In this fluid support pad, the cleaning fluid sprayed from the outflow vias impacts the back side of the wafer and then flows laterally to the adjacent return vias before being discharged, thus creating a continuously renewing lateral micro-circulation flow field within the gap. This flow mechanism ensures that the back side of the wafer is always in contact with fresh cleaning fluid and continuously carries away particulate contaminants detached from the back side of the wafer, effectively preventing particles from accumulating and re-attaching within the support pad, significantly improving the cleaning effect on the back side of the wafer.

[0026] At the same time, since there is no solid contact between the wafer and the supporting chassis 61, the risk of scratches or microcracks caused by mechanical contact is completely eliminated.

[0027] Furthermore, the fluid support pad possesses elastic potential well characteristics. When the wafer moves closer to the support chassis 61 due to minor external disturbances, the thickness of the fluid support pad decreases, causing a sharp increase in the outflow dynamic pressure, thereby automatically pushing the wafer back to its equilibrium position. Conversely, when the wafer moves slightly away from the support chassis 61, the increased gap strengthens the drainage negative pressure effect, automatically pulling the wafer back to its equilibrium position. This process is entirely spontaneously completed by fluid dynamics effects, maintaining stable wafer suspension without the need for external sensors or an active closed-loop control system, greatly simplifying system complexity and improving reliability.

[0028] To achieve the rotational cleaning of the wafer, the inner cavity of the support chassis 61 is also provided with an annular cleaning chamber 67. This cleaning chamber 67 is aligned and connected with multiple liquid through holes 63 of the water outlet through hole group in the outer ring region. A shielding slide 68 is slidably fitted inside the cleaning chamber 67. Multiple protective shells 64 are fixedly mounted circumferentially on the outer wall of the support chassis 61. A transmission module 69 is fixedly mounted inside each protective shell 64. The driving end of the shielding slide 68 is engaged and fixedly connected to the moving end of the transmission module 69.

[0029] During operation, the transmission module 69 drives the shielding slide 68 to slide in a preset direction within the cleaning chamber 67. The shielding slide 68 is designed to obliquely block part of the water outlet hole, causing the direction of the cleaning fluid flowing through that area to deviate from the vertical axis of the liquid outlet hole 63, generating a tangential velocity component parallel to the back surface of the wafer. The tangential velocity components generated by each shielding slide 68 are in the same direction, and these unidirectional tangential impact forces act together on the outer edge region of the back surface of the wafer, forming a net tangential impact torque that drives the wafer to rotate around its own central axis.

[0030] By adjusting the movement of the shielding slider 68 through the transmission module 69, the degree of obstruction of the outer ring water outlet through-hole group can be continuously and steplessly changed, thereby adjusting the effective water flow rate that generates the tangential driving force. This allows for precise control of the wafer rotation speed to meet the different rotation speed requirements of various cleaning process steps. The liquid through-holes 63 located in the inner and middle ring regions, since they do not have shielding sliders 68 and their water outlet direction remains vertical, only provide vertically upward suspension support dynamic pressure and do not participate in the wafer rotation drive. This decoupled design in structure and function achieves independent control of the wafer suspension support force and the rotation drive torque, ensuring they do not interfere with each other.

[0031] In one embodiment, details of the aforementioned support mechanism 5 are described by way of example. The support mechanism 5 includes a hollow shaft 51, a water-blocking baffle 52, and a connecting seat 53. The hollow shaft 51 is rotatably inserted into the central through-hole of the working top plate 4 via bearings. A liquid transmission channel is axially formed along the central axis of the hollow shaft 51. One end of the liquid transmission channel is connected to the liquid supply system inside the cabinet 1, and the other end is connected to the bottom liquid pipe 65 of the wafer tray 6, for conveying cleaning fluid. The water-blocking baffle 52 is a disc-shaped structure, integrally formed or fixedly assembled to the outer wall of the middle portion of the hollow shaft 51. A sealing ring is provided between the bottom surface of the water-blocking baffle 52 and the top surface of the working top plate 4 to form a sealing structure. The connecting seat 53 is a flange structure, fixedly assembled to the top of the water-blocking baffle 52, and rigidly connected to the bottom of the supporting chassis 61 by bolts.

[0032] By setting up the water-blocking baffle 52, when cleaning fluid accidentally seeps out from the central area of ​​the wafer tray 6 and flows downward along the outer wall of the connecting seat 53, the liquid is effectively blocked by the water-blocking baffle 52 and drips down its outer edge into the drainage groove of the working top plate 4. This blocks the path of liquid leakage downward from the gap between the hollow shaft 51 and the working top plate 4 into the cabinet 1, playing a crucial role in protecting the electrical components inside the cabinet 1, such as the liquid supply system, control system, and power module, from liquid corrosion, thereby improving the long-term safety and service life of the equipment.

[0033] In one embodiment, the structure of the aforementioned transmission module 69 is described exemplarily. The transmission module 69 specifically includes a drive motor 691, a signal control component 692, a lead screw 694, a limit guide rod 693, a moving lead nut 695, and a protective bracket 696.

[0034] The drive motor 691 is fixedly mounted on the inner wall of the protective housing 64, and the signal control component 692 is fixedly mounted on the outer wall of the drive motor 691.

[0035] The lead screw 694 is coaxially and fixedly connected to the output end of the drive motor 691 via a coupling.

[0036] The limiting guide rod 693 is arranged parallel to the screw 694, with one end fixed to the outer wall bracket of the drive motor 691. The middle part of the movable nut 695 is threaded to the outer surface of the screw 694, while its side is slidably sleeved on the limiting guide rod 693. The protective bracket 696 is a U-shaped bracket, with the ends of the limiting guide rod 693 and the screw 694 rotatably connected to their respective ends, providing stable support for the entire screw transmission pair. The driving end of the shielding slide 68 is engaged and fixed to the movable nut 695.

[0037] When the control system issues an adjustment command, the signal control unit 692 receives and processes the command, driving the drive motor 691 to output a precise rotation angle.

[0038] The rotational motion is converted by the screw 694 into a precise linear translation of the movable nut 695 along the limiting guide rod 693, which in turn drives the shielding slide 68, which is engaged with the movable nut 695, to move smoothly and precisely within the cleaning chamber 67.

[0039] This lead screw and nut transmission method enables continuous stepless adjustment of the position of the shielding slide 68, providing structural assurance for precise control of the effective flow area and tangential flow rate of the water outlet orifice.

[0040] Preferably, the drive motor 691 is a miniature stepper motor; Signal control unit 692 is a control board with an encoder.

[0041] Using a stepper motor allows for convenient and precise control of its rotation angle and speed through the number of pulses. Combined with a control board equipped with an encoder, a high-precision position and speed closed-loop control system can be formed to ensure the adjustment of the movement of the shielding slider 68.

[0042] The shielding slide 68 is made of polytetrafluoroethylene, and its thickness is matched with the height of the cleaning chamber 67 with a small gap.

[0043] Polytetrafluoroethylene (PTFE) material has an extremely low coefficient of friction and excellent chemical corrosion resistance. The small gap fit ensures that the shielding slide 68 slides smoothly without the risk of jamming, while also effectively preventing the cleaning fluid from flowing into the cleaning chamber 67, thus ensuring the accuracy of flow regulation.

[0044] Furthermore, the protective housing 64 and the outer wall of the supporting chassis 61 are detachably sealed together by a sealing ring and screws. This allows maintenance personnel to independently remove a single protective housing 64 along with its internal drive module 69 for maintenance, repair, or replacement when needed, without disassembling the entire wafer tray 6, significantly reducing equipment maintenance costs and downtime.

[0045] In one embodiment, a megaacoustic transducer array (not shown) is embedded inside or on the lower surface of the substrate of the supporting chassis 61. The operating frequency of the megaacoustic transducer array is set in the range of 0.8MHz to 1.2MHz, and the substrate material of the supporting chassis 61 is quartz. Quartz material has a high acoustic impedance matching degree with the cleaning fluid (such as water), and compared with metal materials, the sound wave reflection loss at the interface between quartz and liquid is smaller, resulting in higher sound wave transmission efficiency.

[0046] After the megaacoustic transducer array is started, the sound waves it generates are conducted and coupled to the fluid support pad on the back of the wafer via the quartz substrate of the supporting chassis 61 and the liquid column filling the liquid through-hole 63.

[0047] The conduction path is composed entirely of solid quartz and liquid, with no direct contact points between the solid and the wafer. This eliminates the huge energy loss caused by repeated refraction and transmission of acoustic energy between multiple solid-solid and solid-liquid interfaces such as transducers, tank walls, and wafers in traditional solid-contact megaacoustic cleaning.

[0048] Furthermore, the thickness δ of the fluid support pad is set to satisfy the standing wave resonance condition, i.e., δ = n × λ / 2. Here, λ is the wavelength of the acoustic wave in the cleaning fluid at a specific operating frequency, and n is a positive integer.

[0049] For example, when the operating frequency is 1MHz, the speed of sound in ultrapure water is about 1500m / s, and the calculated wavelength λ is 1.5mm. Half the wavelength λ / 2 is 0.75mm.

[0050] Under standing wave resonance, a stable sound pressure distribution will form inside the fluid support pad, and the sound radiation force will reach its maximum value on the sound pressure nodal surface.

[0051] Tiny particulate contaminants attached to the back of the wafer will migrate and accumulate directionally towards the acoustic pressure wave nodal under the influence of acoustic radiation force.

[0052] Subsequently, these aggregated particulate pollutants are efficiently carried away by the transverse microcirculation liquid flow from the effluent through-hole group to the return water through-hole group, and are finally discharged through the return water through-hole group.

[0053] The synergistic mechanism of acoustic field focusing and liquid flow removal has a significantly higher particle removal efficiency than simple mega-acoustic stirring or traditional solid contact conduction methods.

[0054] Furthermore, since the megasonic energy is evenly distributed and acts on the entire back side of the wafer, it avoids the damage to the nanoscale device structure that may be caused by excessively high local acoustic energy density; at the same time, it also fundamentally avoids the risk of edge cracking caused by the mechanical vibration of the transducer transmitted to the edge of the wafer in traditional solid contact megasonic waves.

[0055] In one embodiment, the return water through-hole assembly can be connected to a negative pressure return water pump in addition to natural drainage. By actively applying external negative pressure, the renewal rate of the transverse micro-circulation flow field from the outlet water through-hole to the return water through-hole within the fluid support pad can be further enhanced, thereby further improving the removal efficiency of particulate contaminants on the back side under specific process requirements.

[0056] In one embodiment of the spray arm 8, the spray arm 8 includes a cleaning nozzle and a cleaning pipe. The cleaning pipe is a hollow pipe, with one end connected to a liquid supply line and the other end fitted with a cleaning nozzle; and multiple cleaning nozzles at different angles are arranged side by side on the outer wall of the cleaning pipe.

[0057] The multi-angle nozzle design allows for a wider spray coverage area, ensuring uniform chemical spraying and deionized water rinsing of all areas on the wafer surface during the oscillation process, eliminating cleaning dead zones.

[0058] This application also provides a wafer cleaning method based on the above-described semi-automatic wafer cleaning machine, including the following steps.

[0059] In step S1, during loading and pre-stabilization, the operator places the wafer to be cleaned into the surface sink 62 of the support chassis 61 and selects a preset cleaning program through the interactive panel 3. Subsequently, the control unit starts the liquid supply system. The cleaning fluid is supplied to the bottom liquid pipe 65 and the outer liquid pipe 66 of the wafer tray 6 through the liquid transmission channel in the hollow shaft 51 of the support mechanism 5. Finally, it is sprayed upward from the water outlet hole group of each concentric ring area at a preset flow rate. At the same time, the return water hole group is connected to the external drainage channel for natural drainage. Under the combined action of the upward dynamic pressure of the water outlet hole group and the negative pressure of the return water outlet hole group, a fluid support pad with a thickness of 0.5mm to 1.5mm is quickly established and maintained between the back side of the wafer and the upper surface of the support base 61, so that the wafer is stably suspended and has no solid contact with the support base 61. In step S2, during the rotary start-up, the control unit drives the transmission module 69 via a control signal. The drive motor 691 rotates precisely, and the shielding slide 68 is adjusted to the target position via the screw 694 and the movable nut 695 to set the tangential water flow rate of the outer ring water outlet hole group. At this time, the cleaning fluid flowing out of the outer ring water outlet group generates a tangential impact torque in the same direction, driving the wafer to rotate smoothly around its central axis to the target speed. During this process, the liquid through-holes 63 in the inner and middle ring regions maintain vertical water flow, continuously providing dynamic pressure for suspension support, ensuring that the wafer maintains a stable suspension height while rotating.

[0060] In step S3, chemical cleaning, the megaacoustic transducer array is started at an operating frequency of 0.8MHz to 1.2MHz, and the acoustic energy is efficiently coupled to the fluid support pad through the quartz substrate supporting the chassis 61. The control system maintains the fluid support pad thickness δ to meet the standing wave resonance condition by stabilizing the liquid supply pressure and flow rate, forming a stable standing wave field in the liquid film, and using acoustic radiation force to drive the back particles to migrate towards the wave node surface and be carried away by the transverse liquid flow. Meanwhile, the side motor 7 drives the spray arm 8 to swing above the wafer, and the cleaning nozzles at different angles on it spray chemical cleaning solution evenly onto the front side of the wafer to achieve chemical cleaning of the front side.

[0061] In step S4, during deionized water rinsing and unloading, the spray arm 8 is switched to deionized water supply to rinse the front side of the wafer with deionized water to remove residual chemical cleaning solution. After rinsing, the control unit issues a command to gradually reduce the flow rate and pressure of the liquid supply system to the water outlet hole group. The thickness of the fluid support pad gradually decreases, and finally, under the action of gravity, the wafer falls smoothly and without impact back into the surface sink 62 of the support chassis 61. Once the wafer has come to a complete stop, the operator can remove the cleaned wafer, completing one full cleaning cycle.

[0062] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, 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 process, method, article, or apparatus.

[0063] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended technical solutions and their equivalents.

Claims

1. A semi-automatic wafer cleaning machine, comprising a base cabinet (1), a working top plate (4) fixedly mounted on the top of the base cabinet (1), a splash guard (2) fixedly mounted on the top of the working top plate (4), an interactive panel (3) fixedly mounted on the top of the splash guard (2), a support mechanism (5) fixedly mounted on the top of the center of the working top plate (4), a wafer tray (6) fixedly mounted on the top of the support mechanism (5), side motors (7) fixedly mounted on both sides of the working top plate (4), and spray rocker arms (8) fixedly mounted on the output ends of the side motors (7), characterized in that: The wafer tray (6) includes a support base (61), the top of the support base (61) is provided with a surface groove (62), and the bottom of the surface groove (62) is evenly distributed with a plurality of liquid through holes (63) in multiple concentric annular areas. The liquid through holes (63) are divided into a water outlet through hole group and a water return through hole group. A bottom liquid pipe (65) is fixedly installed at the bottom center of the supporting chassis (61). The bottom liquid pipe (65) is connected to several liquid through holes (63) in the inner ring area to form an inner ring water outlet through hole group. An outer liquid pipe (66) is fixedly installed on the outer wall of the bottom liquid pipe (65). The outer liquid pipe (66) is connected to several liquid through holes (63) in the middle ring area and the outer ring area in a spaced manner to form a middle ring and outer ring water outlet through hole group. The remaining liquid through holes (63) form a return water through hole group. The return water through hole group is connected to the external drainage passage, and the cleaning liquid is naturally discharged through the return water through hole group. The water outlet hole group and the water return hole group are alternately arranged on the upper surface of the support chassis (61), so that the wafer is suspended above the support chassis (61) at a predetermined distance under the combined action of the upward dynamic pressure generated by the water outlet hole group and the drainage negative pressure formed by the water return hole group. A fluid support pad with a thickness of 0.5mm to 1.5mm is formed between the back side of the wafer and the upper surface of the support chassis (61). The cleaning liquid in the fluid support pad flows laterally between the water outlet hole group and the water return hole group to refresh the back cleaning liquid and carry away the desorbed particles. The outer wall of the supporting chassis (61) is fixedly fitted with several protective shells (64) along the circumferential direction. The transmission module (69) is fixedly fitted inside the protective shells (64). The inner cavity of the supporting chassis (61) is provided with a cleaning chamber (67). The cleaning chamber (67) coincides with several liquid through holes (63) of the water outlet through hole group. A shielding slide (68) is slidably sleeved inside the cleaning chamber (67). The shielding slide (68) is engaged with the moving end of the transmission module (69). The effective flow area of ​​the water outlet through hole group is adjusted by the movement of the shielding slide (68) in the cleaning chamber (67).

2. The semi-automatic wafer cleaning machine according to claim 1, characterized in that: The substrate of the supporting chassis (61) is fitted with a megohmonic transducer array inside or on the lower surface. The megohmonic transducer array operates at a frequency of 0.8MHz to 1.2MHz. The substrate of the supporting chassis (61) is made of quartz.

3. The semi-automatic wafer cleaning machine according to claim 1, characterized in that: The shielding slider (68) causes the water outlet direction to deviate from the axis of the liquid through hole (63) and generates a tangential velocity component parallel to the back side of the wafer. The tangential components of each shielding slider (68) have the same direction.

4. The semi-automatic wafer cleaning machine according to claim 1, characterized in that: The support mechanism (5) includes a hollow shaft (51), a water-blocking baffle (52), and a connecting seat (53); The hollow shaft (51) is rotatably inserted into the central through hole of the working top plate (4) through a bearing. A liquid transmission channel is provided along the axial direction at the central axis of the hollow shaft (51). The liquid transmission channel is connected to the bottom liquid pipe (65). The connecting seat (53) is a flange structure, which is fixedly assembled on the top of the water-blocking baffle (52) and rigidly connected to the bottom of the bearing chassis (61).

5. The semi-automatic wafer cleaning machine according to claim 1, characterized in that: The transmission module (69) includes a drive motor (691), a signal control component (692), a screw (694), a limit guide rod (693), a movable nut (695), and a protective bracket (696). The drive motor (691) is fixedly mounted on the inner wall of the protective housing (64), and the signal control component (692) is fixedly mounted on the outer wall of the drive motor (691); the screw (694) is coaxially fixedly mounted on the output end of the drive motor (691), and the limiting guide rod (693) is arranged parallel to the screw (694); the middle part of the movable nut (695) is threaded to the outer surface of the screw (694), and the side of the movable nut (695) is slidably sleeved on the limiting guide rod (693); the protective bracket (696) is a U-shaped bracket, and the ends of the limiting guide rod (693) and the screw (694) are rotatably connected to the two ends of the protective bracket (696) respectively; the driving end of the shielding slide (68) is engaged and fixed with the movable nut (695).

6. The semi-automatic wafer cleaning machine according to claim 5, characterized in that: The drive motor (691) is a miniature stepper motor; the signal control unit (692) is a control board with an encoder, used to receive control signals and precisely control the rotation angle and speed of the drive motor (691).

7. The semi-automatic wafer cleaning machine according to claim 1, characterized in that: The shielding slide (68) is made of polytetrafluoroethylene, and its thickness is matched with the height of the cleaning chamber (67) with a small gap.

8. The semi-automatic wafer cleaning machine according to claim 1, characterized in that: The protective outer shell (64) and the outer wall of the supporting chassis (61) are detachably sealed together by a sealing ring and screws.

9. The semi-automatic wafer cleaning machine according to claim 1, characterized in that: The spray rocker arm (8) includes a cleaning nozzle and a cleaning pipe. The cleaning pipe is a hollow pipe with one end connected to a liquid supply line and the other end equipped with the cleaning nozzle. Multiple cleaning nozzles at different angles are arranged side by side on the outer wall of the cleaning pipe.

10. A wafer cleaning method based on the semi-automatic wafer cleaning machine according to any one of claims 1 to 9, characterized in that, Includes the following steps: Step S1, loading and pre-stabilization: The operator places the wafer to be cleaned in the surface sink (62) and selects the cleaning program through the interactive panel (3); the control unit starts the water outlet hole group, and the water outlet hole group sprays the cleaning liquid upward through the bottom liquid pipe (65) and the outer liquid pipe (66) at a preset flow rate. The return water hole group is connected to the external drainage channel for natural drainage, and a fluid support pad is established between the back of the wafer and the upper surface of the support base (61), so that the wafer is suspended above the support base (61) and has no solid contact with the upper surface of the support base (61); Step S2, Rotation Start: The control unit adjusts the shielding slide (68) corresponding to the water outlet hole group in the outer ring area to the target position through the transmission module (69), so that the water outlet hole group in the outer ring generates a tangential impact torque, driving the wafer to rotate around the central axis to the target speed; the water outlet direction of the liquid through holes (63) in the inner ring area and the middle ring area remains vertical, only providing suspension support dynamic pressure; Step S3, chemical cleaning: The mega-sonic transducer array is started at a working frequency of 0.8MHz to 1.2MHz. The acoustic wave is coupled to the back of the wafer through the substrate (61) and the fluid support pad. The thickness δ of the fluid support pad is maintained at the standing wave resonance condition δ=n×λ / 2. The side motor (7) drives the spray arm (8) to swing above the wafer, and the cleaning nozzle sprays chemical cleaning solution onto the front of the wafer. Step S4, deionized water rinsing and unloading: The spray arm (8) switches to deionized water to rinse the front side of the wafer; after cleaning, the water supply through the outlet hole group is gradually closed, and the wafer falls back smoothly into the surface sink (62) under the action of gravity, and the operator takes out the wafer.

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