Wafer cleaning apparatus and wafer cleaning method

Abstract

The application provides a wafer cleaning device and a wafer cleaning method, and belongs to the technical field of wafer processing. The wafer cleaning device comprises a bearing disc, a lower blocking ring, an upper blocking ring and a uniform flow structure. The lower blocking ring is arranged on the lower side outside the bearing disc. The upper blocking ring is arranged on the upper side outside the bearing disc and forms a gap with the lower blocking ring. The uniform flow structure is arranged below the inner side of the upper blocking ring and is used for uniformly distributing the radial pressure in the upper blocking ring and blocking the diffusion of high-pressure fluid to the gap. The uniform flow structure is further provided with a hollow. In wafer cleaning, the uniform flow structure can uniformly distribute the radial pressure in the upper blocking ring, form a uniform flow effect, avoid the formation of a high-pressure area in the inner periphery of the upper blocking ring under the action of centrifugal force and the overflow of the fluid from below the upper blocking ring, the hollow on the uniform flow structure can guide the fluid in the upper blocking ring to the inside of the uniform flow structure, thereby avoiding the secondary pollution caused by the overflow of the fluid from below the lower blocking ring and falling on the wafer surface again, and effectively ensuring the processing quality of the wafer.

Description

[0001] This application is a divisional application of the invention patent application filed on February 27, 2026, with application number 2026102306029. Technical Field

[0002] This application belongs to the field of wafer processing technology, and more specifically, relates to a wafer cleaning apparatus and a wafer cleaning method. Background Technology

[0003] Wafer processing typically includes polishing, cleaning, and drying processes. Currently, chemical mechanical polishing (CMP) is commonly used to remove multi-layered thin films (such as oxide and metal layers) formed on the wafer surface, achieving surface planarization. CMP utilizes the synergistic effect of chemical etching and mechanical abrasion to remove uneven areas on the wafer surface, ensuring the precision of subsequent photolithography and etching processes. After polishing, the wafer needs further cleaning and drying to obtain the finished wafer. During the cleaning process, although an upper baffle is placed on the outer periphery to shield the wafer, there is still a problem of fluid overflowing from below the upper baffle. Summary of the Invention

[0004] In view of the above problems, this application provides a wafer cleaning apparatus and a wafer cleaning method, thereby at least alleviating the problem that fluid easily overflows from below the upper retaining ring during the wafer cleaning process in the prior art.

[0005] A first aspect of this application provides a wafer cleaning apparatus, comprising: Box; The carrier tray, located inside the housing, is used to support the rotation of the wafer; The upper baffle ring is raised and lowered on the outside of the support plate to block the fluid. The flow equalization structure is located on the lower inner side of the upper baffle ring to balance the radial pressure inside the upper baffle ring. The flow equalization structure has a perforation to guide the fluid into its interior, so as to reduce the fluid from overflowing tangentially under the action of centrifugal force.

[0006] In one embodiment, the flow uniform structure includes an annular vertical sidewall and an inner edge extending inward from the top of the vertical sidewall, with cutouts formed in the vertical sidewall and / or the inner edge.

[0007] In some embodiments, multiple circumferentially arranged perforations are provided on both the vertical sidewall and the inner edge. The perforations on the vertical sidewall and the perforations on the inner edge are alternately distributed circumferentially to improve the circumferential uniformity of fluid guidance.

[0008] In some embodiments, a perforation is also provided at the junction of the vertical sidewall and the inner edge to guide the fluid above the outer periphery of the uniform flow structure to flow through the perforation to the bottom of the support plate.

[0009] In one embodiment, the housing has a lower baffle ring extending upward to the outer periphery of the upper baffle ring, forming a gap between the lower baffle ring and the upper baffle ring, and a perforation is provided on the vertical side wall to guide the fluid in the gap into the uniform flow structure.

[0010] In one embodiment, the perforation on the inner edge is inclined from top to bottom toward the inner side of the uniform flow structure, and the angle between the through direction of the perforation and the horizontal plane is α, wherein 3°≤α≤75°, so as to improve the flow direction of the fluids discharged through the perforation on the inner edge and the perforation on the vertical sidewall and reduce the collision between the two fluids.

[0011] In one embodiment, the inner edge is inclined downward from the center of the uniform flow structure to the outer periphery, and the angle between the extension direction of the inner edge and the horizontal plane is β, wherein 3°≤β≤15°, so as to guide the fluid to be discharged below the bearing plate through the hollow on the inner edge, and at the same time guide the liquid in the fluid to be discharged from the top of the inner edge to the outside and downward.

[0012] As a parallel embodiment, another wafer cleaning apparatus is also provided, comprising: A carrier disk is used to support the rotation of the wafer; The lower retaining ring is located on the lower outer side of the bearing plate; The upper retaining ring is located on the upper outer side of the bearing plate; A flow equalization structure is provided between the bearing plate and the lower baffle ring to prevent circumferential pressure distortion and pressure pulsation from occurring on the inner wall of the lower baffle ring when the bearing plate rotates, which would cause fluid to overflow along the gap between the lower baffle ring and the upper baffle ring. The uniform flow structure is formed as a circular hood, consisting of vertical sidewalls and an inner edge extending inward from its top. The vertical sidewalls and / or inner edges are provided with perforations to guide more fluid to drain away from below the support plate.

[0013] As a specific implementation method, the lower edge of the upper baffle ring is located inside the upper edge of the lower baffle ring, and the horizontal distance between the vertical sidewall and the inner wall of the upper baffle ring is d1, 0.5mm≤d1≤4mm, in order to reduce the horizontal distance between the uniform flow structure and the upper baffle ring and avoid interference between the two.

[0014] In one embodiment, the height of the lower edge of the upper baffle ring is lower than the height of the upper edge of the lower baffle ring, but higher than the highest point of the hollowed-out part on the vertical sidewall, so as to extend the flow path of fluid flowing into the gap between the lower baffle ring and the upper baffle ring, and shorten the flow path of fluid flowing into the hollowed-out part on the vertical sidewall.

[0015] In one embodiment, a negative pressure box is also provided below the support plate. The negative pressure box is connected to the inner side of the uniform flow structure through a negative pressure port, and the inner edge extends inward to the gap between the support plate and the negative pressure box.

[0016] In one embodiment, the flow area of ​​the perforated area on the vertical sidewall is 1.5-3 times that of the perforated area on the inner edge. Under the negative pressure of the negative pressure box, the flow guidance capability of the perforated area on the vertical sidewall can be enhanced.

[0017] In one embodiment, the perforations on the vertical sidewall and the perforations on the inner edge both extend circumferentially, and the central angle corresponding to the perforations is 10°-20°. The perforations on the vertical sidewall and the perforations on the inner edge are distributed alternately and intermittently circumferentially, and do not overlap in the circumferential direction, so as to avoid weakening each other's ability to guide the fluid.

[0018] In one embodiment, an inner baffle ring is provided on the inner side of the lower baffle ring, and a receiving cavity is formed between the inner baffle ring and the lower baffle ring. The flow equalization structure is located in the receiving cavity, and a liquid passage hole is provided on the lower edge of the flow equalization structure for liquid to pass through and collect.

[0019] The beneficial effects of this application embodiment are as follows: During the wafer cleaning process, when the carrier disk drives the wafer to rotate, it throws out the fluid. The uniform flow structure set inside the upper baffle ring can uniformly distribute the radial pressure of the fluid, forming a uniform flow effect. This prevents the fluid from forming a high-pressure zone on the inner circumference of the upper baffle ring under the action of centrifugal force and overflowing from below the upper baffle ring. The hollow on the uniform flow structure can guide the fluid in the upper baffle ring into the uniform flow structure, thereby preventing the fluid from overflowing from below the lower baffle ring and falling back onto the wafer surface, causing secondary contamination. At the same time, the fluid after being guided is uniformly discharged from below the carrier disk, realizing the orderly collection and processing of the fluid and effectively ensuring the processing quality of the wafer.

[0020] A second aspect of this application provides a wafer cleaning method, which uses a wafer cleaning apparatus to clean a wafer, including the following steps: The wafer is rotated and cleaned, and the fluid in the upper baffle ring is balanced by the uniform flow structure. The fluid is guided out from below the support plate by the hollowing out to prevent the fluid from overflowing from below the upper baffle ring due to circumferential pressure distortion and pressure pulsation.

[0021] The beneficial effects of this application embodiment are as follows: the uniform flow structure is used to uniformly flow the fluid ejected from the carrier disk and the wafer, avoiding the formation of a high-pressure zone inside the upper baffle ring. At the same time, the hollowed-out structure guides the fluid into the uniform flow structure, preventing the fluid from overflowing outward from the gap between the upper and lower baffle rings, thereby preventing the fluid from flowing back to the wafer surface and causing secondary pollution. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the front cross-sectional structure of a wafer cleaning apparatus provided in an embodiment of this application; Figure 2 For this application Figure 1 A schematic diagram of a local structure in the image; Figure 3 For this application Figure 2 A magnified schematic diagram of the structure of part A in the diagram; Figure 4 For this application Figure 1 Enlarged schematic diagram of the upper and middle baffle rings, the flow equalization structure, and the lower baffle ring; Figure 5 For this application Figure 1 Axonometric view of a uniform flow structure; Figure 6 An enlarged structural schematic diagram of another embodiment of the flow uniformity structure provided in this application; Figure 7 This is a schematic diagram of the front cross-sectional structure of a wafer cleaning device in the prior art.

[0024] Figure label: 1. Lower retaining ring; 11. Gap; 12. Inner retaining ring; 13. Receiving cavity; 14. Box body; 15. Lower base; 2. Bearing plate; 21. Clamping claw; 3. Upper retaining ring; 4. Uniform flow structure; 41. Vertical side wall; 42. Inner edge; 43. Hole; 44. Liquid passage hole; 5. Negative pressure box; 51. Negative pressure port; 6. Wafer. Detailed Implementation

[0025] To enable those skilled in the art to better understand the technical solutions in the embodiments of this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments in the specific implementation of this application should fall within the protection scope of the embodiments of this application.

[0026] To keep the drawings concise, each drawing only schematically shows the parts relevant to the disclosure; these do not represent the actual structure of the product. Furthermore, for ease of understanding, in some drawings, only one of components with the same structure or function is schematically shown, or only one is labeled. In this document, "one" not only means "only one," but can also mean "more than one," and "several" includes "two" and "more than two."

[0027] In this document, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0028] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0029] In the description of this embodiment, terms such as "upper," "lower," "left," and "right" are based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of description and simplification of operation, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0030] Furthermore, in the description of this application, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0031] It should be understood that, unless the context clearly states otherwise, the terms "comprising," "including," or "having" as used herein refer to the presence of an element, but do not exclude the presence or addition of one or more other elements. Furthermore, "comprising" and / or "including" as used herein specify the presence of shapes, numbers, steps, operations, members, elements, and / or combinations thereof, and do not exclude the presence or addition of one or more other shapes, numbers, operations, elements, and / or combinations thereof. Some embodiments of this application are described in detail below with reference to the accompanying drawings. Where there is no conflict between the embodiments, the following embodiments and features can be combined with each other. The steps in the following method embodiments are for illustrative purposes only and are not intended to limit this application.

[0032] After chemical mechanical polishing (CMP), wafer 6 still requires post-processing steps such as cleaning and drying. Wafer 6 cleaning is one of the most crucial steps, aiming to remove contaminants, impurities, and residual reactants from the wafer 6 surface to ensure the processing accuracy and product yield of subsequent photolithography, etching, and deposition processes. In traditional technologies, wafer 6 cleaning operates at relatively low speeds, typically between 1000-3000 rpm. The clamping jaws 21 are small, resulting in minimal fluid overflow during wafer 6 rotation, which is simple radial overflow and has limited impact on cleaning quality.

[0033] It should be noted that the wafer cleaning device is suitable for both the cleaning and drying processes of wafer 6. Both cleaning and drying of wafer 6 utilize the Marangoni effect. In the drying process of wafer 6, the Marangoni effect is a key technological principle, maturely applied in advanced processes. By creating a surface tension gradient on the wafer surface, it drives the directional flow and peeling of the residual liquid film, achieving watermark-free drying. During this drying process, the liquid film peeling simultaneously removes tiny contaminants remaining on the wafer surface, such as 0.12μm particles, thus also providing an auxiliary cleaning effect. In the cleaning process of wafer 6, the Marangoni effect is not directly used as the core decontamination mechanism for horizontal cleaning, but it can help improve cleaning efficiency and contaminant removal rate by optimizing the uniformity of fluid flow. Therefore, the above device is suitable for both wafer 6 cleaning and drying scenarios. To avoid fluid overflow during the cleaning process, affecting the surrounding environment and the normal operation of other components, and causing secondary contamination of wafer 6, existing wafer cleaning devices typically have a retaining ring structure on the outside of the carrier tray 2. Please refer to [link to relevant documentation]. Figure 7 Existing cleaning devices typically have an upper baffle ring 3 and a lower baffle ring 1 around the outer periphery of the carrier plate 2. The upper baffle ring 3 can move up and down. When the wafer 6 is in the cleaning state, the upper baffle ring 3 moves up to a high position to block the fluid, and a gap 11 is formed between the lower edge of the upper baffle ring 3 and the upper edge of the lower baffle ring 1. When the wafer 6 is finished cleaning and another wafer 6 needs to be replaced, the upper baffle ring 3 moves down to a low position to avoid the upper wafer 6.

[0034] When the carrier disk 2 rotates the wafer 6, under the action of centrifugal force, the fluid will accumulate in the area near the inner wall of the upper baffle ring 3, forming a high-pressure zone. Meanwhile, the fluid near the center of the main shaft of the carrier disk 2 is relatively dispersed, forming a low-pressure zone in the center area of ​​the main shaft. Therefore, under high pressure, the fluid in the area near the inner wall of the upper baffle ring 3 easily overflows through the gap 11 and splashes onto the surface of the wafer 6 from above and outside the upper baffle ring 3, severely affecting the cleaning quality of the wafer 6 and reducing its cleaning efficiency.

[0035] Meanwhile, as the carrier disk 2 rotates the wafer 6, it causes the fluid on its outer side to move in a circular motion. Under the influence of centrifugal force, frictional resistance against the inner wall of the lower retaining ring 1, and impact with the inner wall of the lower retaining ring 1, the fluid will generate circumferential pressure distortion on the inner wall of the lower retaining ring 1. At the same fixed position on the inner wall of the lower retaining ring 1, the fluid pressure will repeatedly and rapidly oscillate high and low over time, forming pressure pulsations, which will cause the fluid to overflow outward along the gap 11 between the lower retaining ring 1 and the upper retaining ring 3.

[0036] As the semiconductor industry evolves towards advanced processes, large-size wafers (12 inches and above) have become the mainstream carrier for high-end chips, power devices, and other fields. For large-size wafers (12 inches and above) using advanced processes such as 28nm, 14nm, and 7nm, after chemical mechanical polishing (CMP), they require cleaning and drying processes. Because the precision requirements for controlling surface contaminants on large-size wafers have increased to below 0.18μm, and even below 0.12μm for 14nm and below processes, horizontal cleaning has become the only suitable method. Horizontal cleaning of large-size wafers requires high speeds of 3000-6000 rpm. For processes below 28nm, the speed is typically above 6000 rpm, and for processes below 14nm, it can reach above 8000 rpm. Strong centrifugal force is used to optimize fluid flow, assist in improving cleaning efficiency, or quickly remove residual liquid films from the wafer surface to meet the cleaning or drying requirements of large-size wafers.

[0037] In the aforementioned high-speed scenario, the centrifugal force generated by the rotating wafer 6 driven by the carrier disk 2 increases significantly. Simultaneously, to ensure stable clamping of the wafer 6, the size of the clamping claws 21 also increases accordingly, and their number increases from three to four or six. The airflow disturbance generated during rotation is significantly enhanced, leading to increased friction and impact with the inner wall of the lower retaining ring 1. This causes airflow to overflow tangentially from the gap 11 between the upper retaining ring 3 and the lower retaining ring 1 at high tangential velocity. The synergistic effect of the high rotational speed of the carrier disk 2 and the increased number and size of the clamping claws 21 intensifies the turbulent disturbance of the fluid, significantly increasing the fluid pressure inside the upper retaining ring 3. This further makes it easier for the fluid in the inner wall region of the upper retaining ring 3 to break through the constraint of the upper retaining ring 3 tangentially, resulting in tangential overflow from below the upper retaining ring 3. Traditional retaining ring structures cannot alleviate this pressure pulsation, and the fluid easily overflows through the lower region of the upper retaining ring 3. The overflowing fluid carries tiny contaminants and flows back along the outside of the upper retaining ring 3 to the surface of the wafer 6. This secondary contamination has a significant impact on the yield of the advanced process wafer 6.

[0038] Specifically, at high wafer rotation speeds (≥6000rpm for processes below 28nm, ≥8000rpm for processes below 14nm), the centrifugal force increases quadratically, and the fluid is rapidly thrown towards the outer periphery of wafer 6, resulting in sparse fluid in the central region, becoming a low-pressure area, while the fluid accumulates in the inner wall region of the upper baffle ring 3, becoming a high-pressure area, forming a significant radial pressure gradient. At the same time, at high rotation speeds, the size and number of gripping claws 21 increase, and the airflow disturbance during their rotation becomes nonlinearly enhanced, further disrupting the uniformity of circumferential fluid distribution, leading to sudden pressure changes in local areas and forming circumferential pressure unevenness.

[0039] At the same time, the high rotation speed greatly increases the frequency of friction and impact between the fluid and the inner wall of the lower baffle ring 1. The above phenomenon is positively correlated with the rotation speed. The fluid repeatedly experiences the dual effects of impact pressurization and rebound decompression at the same position on the inner wall of the lower baffle ring 1, forming high-frequency pressure oscillation, that is, pressure pulsation. Meanwhile, the uneven circumferential pressure causes the fluid to flow rapidly between the high-pressure area and the low-pressure area, further amplifying the amplitude of pressure pulsation, and the two form a vicious cycle.

[0040] In summary, traditional wafer cleaning devices are designed only for low-speed scenarios and cannot solve a series of problems caused by pressure distortion and tangential overflow at high speeds. During the cleaning process of wafer 6, uneven circumferential pressure and pressure pulsation caused by high speed result in fluid overflowing tangentially from below the upper baffle ring 3. These problems not only affect the cleaning quality and efficiency of wafer 6, but may also damage related equipment components due to fluid overflow, increasing production costs. Therefore, there is an urgent need for a wafer cleaning device that can solve these defects.

[0041] Please see Figure 1 In a first aspect, this application provides a wafer cleaning apparatus, including a housing 14, a carrier tray 2, an upper retaining ring 3, and a flow equalization structure 4. The housing 14 has an opening for feeding or removing a wafer 6, which can be located on the side or top of the housing 14. The carrier tray 2 is disposed in the housing 14 and has a plurality of clamping claws 21 that can cooperate with each other to hold the wafer 6. The housing 14 can form a relatively sealed space to prevent the wafer 6 and the cleaning process from being affected by the external environment. The carrier tray 2 is rotatably disposed in the housing 14 to support the wafer 6 and drive the wafer 6 to rotate. A cleaning nozzle located above the carrier tray 2 is provided in the housing 14, through which cleaning fluid is sprayed onto the surface of the wafer 6 to achieve cleaning of the wafer 6 surface.

[0042] The upper baffle ring 3 is positioned outside the support tray 2 and can block the fluid ejected from the wafer 6, preventing it from splashing directly onto the inner wall of the chamber 14. The lower baffle ring 1 is connected to the inner bottom wall of the chamber 14 and is located below the outer periphery of the upper baffle ring 3. When the upper baffle ring 3 moves to a higher position, the lower edge of the upper baffle ring 3 and the upper edge of the lower baffle ring 1 partially overlap in the height direction, requiring the fluid to flow downwards around the lower edge of the upper baffle ring 3 before entering the gap 11 between the upper baffle ring 3 and the lower baffle ring 1. Optionally, the support tray 2 and the upper baffle ring 3 can also be installed directly in the area of ​​the cleanroom where the wafer 6 is to be cleaned, instead of being installed inside the chamber 14. Alternatively, they can be combined with the flow equalization structure 4 to achieve the effect of preventing fluid overflow.

[0043] By setting a flow equalization structure 4 on the lower inner side of the upper baffle ring 3, the radial pressure of the fluid inside the upper baffle ring 3 can be balanced. The fluid contains both gas and liquid, and is in a gas-liquid mixture state. During the fluid movement, due to gravity, some liquid will separate from the fluid and fall along the outer wall of the flow equalization structure 4 into the space between the flow equalization structure 4 and the lower baffle ring 1.

[0044] The uniform flow structure 4 utilizes a circumferentially uniform annular structure to regulate the fluid pressure at different locations on the outer periphery of the wafer 6. After the fluid is ejected from the outer periphery of the wafer 6, it flows upward to the inner wall of the upper baffle ring 3 under the action of centrifugal force. During this process, the top wall of the uniform flow structure 4 can uniformly distribute the fluid circumferentially. Simultaneously, after the fluid contacts the inner wall of the upper baffle ring 3, due to the extremely small distance between the outer wall of the uniform flow structure 4 and the inner wall of the upper baffle ring 3, the fluid will not flow directly downward along the inner wall of the upper baffle ring 3. Instead, it will be further uniformized under the action of the uniform flow structure 4, reducing the pressure value on the inner periphery of the upper baffle ring 3. Combined with the setting of the perforation 43, fluid with a certain pressure can be guided through the perforation 43 into the interior of the uniform flow structure 4, forming an effective isolation from the surface of the wafer 6. This prevents the formation of excessively high pressure areas on the inner periphery of the upper baffle ring 3 and the lower baffle ring 1, which would cause the fluid to overflow from the gap 11, thus avoiding contamination of the wafer 6.

[0045] The flow equalization structure 4 is a circumferential ring structure, located inside the lower baffle ring 1. Its height is lower than the support plate 2 but higher than the lower edge of the upper baffle ring 3. This prevents the fluid from directly acting downwards along the inner wall of the upper baffle ring 3 onto the inner wall of the lower baffle ring 1, thus avoiding uneven circumferential pressure and pressure pulsation. The small gap between the outer circumferential wall of the flow equalization structure 4 and the inner circumferential wall of the upper baffle ring 3 prevents most of the fluid from flowing directly through the gap between them into the gap 11 formed by the upper baffle ring 3 and the lower baffle ring 1. The top surface of the flow equalization structure 4 has a certain degree of flatness and extends inwards to below the support plate 2, allowing the fluid to flow along its top surface, thereby guiding the fluid to be evenly distributed and preventing the formation of high-pressure zones on the inner walls of the upper baffle ring 3 and the lower baffle ring 1, thus avoiding fluid overflow due to excessive regional pressure. Specifically, the flow equalization structure 4 can be configured as a cover structure, with its inner ring forming a cavity communicating with the lower part of the support plate 2, achieving sufficient guidance of the fluid.

[0046] It should be noted that the flow equalization structure 4 is applicable to various scenarios. Firstly, it is suitable for scenarios where the upper baffle ring 3 and lower baffle ring 1 are combined. In this scenario, the upper baffle ring 3 and lower baffle ring 1 cooperate, forming a gap 11 between them, which can lead to fluid overflow. Secondly, the flow equalization structure 4 is also suitable for scenarios where a groove is formed on the inner bottom wall of the housing 14, and the inner sidewall of the groove connects with the lower edge of the upper baffle ring 3. The lower edge of the upper baffle ring 3 is located within the groove, and a gap 11 is formed between the upper baffle ring 3 and the inner sidewall of the groove, again leading to fluid overflow. Thirdly, the flow equalization structure 4 is also suitable for scenarios where the upper baffle ring 3 is used alone. The upper baffle ring 3 covers the outer periphery of the wafer 6 and is raised and lowered within the housing 14. A gap 11 is formed between the upper baffle ring 3 and the inner bottom wall of the housing 14, and fluid still overflows from the gap 11.

[0047] In all the above scenarios, a uniform flow structure 4 can be set below the inner side of the upper baffle ring 3 to achieve a uniform effect on the radial pressure of the fluid. At the same time, the hollow 43 is used to guide the fluid into the interior of the uniform flow structure 4, so as to avoid the fluid splashing affecting the surface quality of the wafer 6.

[0048] In one embodiment, the flow equalization structure 4 adopts a structure combining a vertical sidewall 41 and an inner edge 42. The vertical sidewall 41 is a circular cylindrical structure with a small gap between its outer periphery and the inner wall of the upper baffle ring 3, forming a sealing effect on the lower part of the inner cavity of the upper baffle ring 3, preventing fluid from diffusing into the gap 11. The inner edge 42 is connected to the top of the vertical sidewall 41 and extends inward, that is, towards the center of the bearing plate 2. Holes 43 can be formed on the vertical sidewall 41 and the inner edge 42 respectively, or a hole 43 can be formed on one of the vertical sidewall 41 and the inner edge 42, using the hole 43 to guide the fluid into the interior of the flow equalization structure 4.

[0049] Specifically, both the vertical sidewall 41 and the inner edge 42 are provided with perforations 43. These perforations 43 are spaced apart circumferentially, effectively covering different positions on the outer perimeter and top circumferentially, thus ensuring uniform fluid guidance. Furthermore, the alternating distribution of perforations 43 on the vertical sidewall 41 and inner edge 42 ensures complete circumferential coverage, preventing abrupt changes in local flow area and improving the circumferential uniformity of fluid guidance.

[0050] The perforation 43 can take different forms, such as round holes, polygonal holes, elongated holes, or elliptical holes. Taking an elongated hole as an example, the elongated hole extends circumferentially along the flow equalization structure 4 to cover a larger area around the flow equalization structure 4, ensuring effective fluid guidance. Furthermore, the extension direction of the elongated hole on the inner edge 42 can intersect with the radial direction of the flow equalization structure 4, avoiding radial placement as much as possible and improving the uniformity of the distribution of the elongated hole circumferentially along the inner edge 42. The elongated hole on the vertical sidewall 41 can be angled with the axial direction of the flow equalization structure 4 to avoid axial placement, thus achieving effective circumferential coverage. These arrangements ensure that the perforation 43 is evenly distributed around the flow equalization structure 4, thereby improving the consistency of fluid guidance and ensuring a comprehensive flow diversion effect.

[0051] Furthermore, a perforation 43 is also provided at the junction of the vertical sidewall 41 and the inner edge 42. This position is where the outer diameter of the uniform flow structure 4 is relatively large, and it is located in the area where the fluid must pass down into the gap 11. By setting the perforation 43 in this area, the fluid above the outer periphery of the uniform flow structure 4 can be effectively guided into the interior of the uniform flow structure 4, that is, the fluid is guided to the bottom of the bearing plate 2, which enhances the guiding effect on the fluid and prevents the fluid from continuing to flow down to the gap 11.

[0052] In some embodiments, fluid enters the uniform flow structure 4 horizontally through the perforation 43 on the vertical sidewall 41. In this case, the perforation 43 on the inner edge 42 is set to be inclined from top to bottom towards the inner side of the uniform flow structure 4, so that the fluid entering through the perforation 43 on the inner edge 42 can be closer to the flow direction of the fluid flowing in through the perforation 43 on the vertical sidewall 41. That is, the two fluids have better co-directionality, avoiding collision between them, and thus avoiding fluid stagnation or eddy current formation at the collision point, so as to optimize the fluid flow path and reduce the risk of fluid overflow.

[0053] Specifically, the angle between the through direction of the perforation 43 on the inner edge 42 and the horizontal plane is α, 3°≤α≤75°, which can be set to 3°, 5°, 10°, 30°, 60° or 75°, in order to improve the flow direction of the fluid flowing in through the perforation 43 on the inner edge 42 and the perforation 43 on the vertical sidewall 41, reduce the collision between the two fluids, and thus reduce the pressure loss of the fluid during the flow process.

[0054] To further limit the fluid flow direction, guide ribs can be provided on the inner top wall of the inner edge 42. The extension direction of the guide ribs is consistent with the inflow direction of the fluid in the hollow 43 on the inner edge 42, which facilitates the smooth entry of the fluid into the uniform flow structure 4, reduces the turbulence and stagnation of the fluid inside the uniform flow structure 4, reduces the fluid flow resistance, and thus enhances the fluid collection effect of the uniform flow structure 4.

[0055] Specifically, multiple guide ribs are spaced apart along the circumference of the uniform flow structure 4. Guide ribs are arranged between two adjacent hollows 43 on the inner edge 42. A guide channel corresponding to and connected to the hollow 43 is formed between two adjacent guide ribs. The guide channel is used to allow the fluid adsorbed by the corresponding hollow 43 to pass smoothly, thereby improving the fluid collection efficiency.

[0056] Based on this, an annular guide plate can be installed on the inner circumferential wall of the uniform flow structure 4. The annular guide plate is located below the perforation 43 on the vertical sidewall 41 and is fixedly connected to the inner wall of the uniform flow structure 4. The annular guide plate extends circumferentially along the uniform flow structure 4 and is gradually inclined downward from the outer circumference of the uniform flow structure 4 to the axis of the uniform flow structure 4. The fluid flowing into the perforation 43 on the vertical sidewall 41 can flow towards the lower part of the bearing plate 2 under the guidance of the annular guide plate, avoiding the formation of resistance between fluids during the flow process and improving the guiding performance of the fluid.

[0057] In one embodiment, the inner edge 42 is inclined downward from the center of the flow uniform structure 4 to the outer periphery, which can quickly guide the liquid in the fluid into the space between the flow uniform structure 4 and the lower baffle ring 1, avoid uneven distribution caused by the liquid spreading on the surface of the inner edge 42, reduce circumferential pressure fluctuations caused by liquid flow, and further improve the flow uniformity effect.

[0058] Specifically, the angle between the extension direction of the inner edge 42 and the horizontal plane is β, where 3° ≤ β ≤ 15°. It can be set to 3°, 5°, 10°, 12°, or 15°. This angle setting avoids an excessively large angle that would increase the width of the inner edge 42, while also achieving a balancing effect on the fluid, ensuring a uniform distribution of fluid within the upper baffle ring 3. The slope of the inner edge 42 also effectively guides the liquid in the fluid to drain outwards and downwards from the top of the inner edge 42, preventing the fluid from flowing into the gap 11 between the upper baffle ring 3 and the lower baffle ring 1. This angle ensures efficient fluid conduction while preventing uneven pressure distribution due to excessive tilting.

[0059] In some embodiments, the lower edge of the upper baffle ring 3 is located inside the upper edge of the lower baffle ring 1. The horizontal distance between the vertical sidewall 41 and the inner wall of the upper baffle ring 3 is d1, where 0.5mm≤d1≤4mm. If the distance is less than 0.5mm, it is easy for the upper baffle ring 3 to interfere with the uniform flow structure 4 when it rises and falls. If the distance is greater than 4mm, it will not be able to block the high-pressure fluid from spreading to the gap 11, thus preventing the subsequent fluid from flowing back from the outside of the upper baffle ring 3 to the surface of the wafer 6 and ensuring the cleaning quality of the wafer 6.

[0060] More importantly, when d1 is set to a very small size, such as less than 0.5 mm, the cleaning solution, after being ejected by the rotation of wafer 6, is not directly carried away by centrifugal force. Instead, it is drawn into the narrow gap between the uniform flow structure 4 and the upper baffle ring 3 by surface tension, forming a stable liquid film or column. Crucially, the high-speed environment of wafer 6 cleaning (≥6000 rpm for processes below 28 nm) accelerates the evaporation of the liquid film. Contaminants dissolved in the cleaning solution (such as silicon powder, metal ions, and organic additives remaining from CMP polishing) cannot evaporate with the water and gradually deposit and crystallize on the inner wall of the gap. These crystals are mostly micron- or even nano-sized particles, which accumulate continuously with each cleaning cycle. Initially, it will reduce the effective flow cross section of the gap and disrupt the pressure balance of the uniform flow structure 4. After long-term use, it will completely block the gap, causing the high-pressure fluid inside the upper baffle ring 3 to be unable to pass through the gap. It can only forcefully break through the gap 11 between the upper baffle ring 3 and the lower baffle ring 1 and overflow. Moreover, the overflowing fluid will carry crystal detachment particles, causing more serious secondary pollution to the wafer surface.

[0061] Setting d1 to 0.5mm or more breaks the conditions for capillary effect formation. The cleaning fluid will quickly leave the gap under centrifugal force and be thrown to the designated collection area, without lingering in the gap, thus avoiding the crystallization and deposition of contaminants. At the same time, the spacing design of less than 4mm ensures that the uniform flow structure 4 and the upper baffle ring 3 form a blocking effect. When the high-pressure fluid diffuses into the gap 11, it will be physically blocked and cannot directly break through, ensuring the blocking effect on the high-pressure fluid.

[0062] Meanwhile, the lower edge of the upper baffle ring 3 is lower than the upper edge of the lower baffle ring 1, but higher than the highest point of the perforation 43 on the vertical sidewall 41. When the perforation 43 absorbs the fluid at the gap 11, the above positional relationship allows the fluid at the gap 11 to smoothly enter the perforation 43 on the vertical sidewall 41 from below the lower edge of the upper baffle ring 3, avoiding the upper baffle ring 3 from obstructing the fluid. In addition, when the fluid flows downward from above the uniform flow structure 4 to the gap 11, the above height relationship requires the fluid to bypass the lower edge of the lower baffle ring 1 and then turn back upward, which facilitates extending the flow path of the fluid to the gap 11, and using the perforation 43 of the uniform flow structure 4 located on this path to effectively guide the fluid.

[0063] For details, please refer to Figure 3 The distance between the outer peripheral wall of the vertical sidewall 41 and the inner peripheral wall of the lower baffle ring 1 is d2, where d2 ≤ 15 mm, to reduce the airflow entering the gap 11 above the uniform flow structure 4. Simultaneously, the distance between the lower edge of the upper baffle ring 3 and the upper edge of the lower baffle ring 1 is d3, where d3 ≥ 10 mm, so that the fluid must bypass the lower edge of the lower baffle ring 1 to enter the gap 11. This effectively isolates the high-pressure area above the uniform flow structure 4 from the area where the gap 11 is located, allowing only a small amount of airflow to enter the gap 11 and reducing fluid overflow. At the same time, the distance between the lower edge of the upper baffle ring 3 and the highest point of the perforation 43 on the vertical sidewall 41 is d4, where d4 ≤ 10 mm, so that the perforation 43 on the vertical sidewall 41 is lower than the lower edge of the upper baffle ring 3 and the upper edge of the lower baffle ring 1. This facilitates the effective backflow of airflow in the gap 11 through the perforation 43 on the vertical sidewall 41, further reducing fluid overflow.

[0064] Furthermore, the lower edge of the upper baffle ring 3 is also provided with an inclined guide slope. The guide slope avoids the fluid at the gap 11 and guides the fluid at the gap 11, so that the fluid flows into the uniform flow structure 4 through the hollow 43 on the vertical side wall 41 along the guide slope, thereby improving the guiding effect on the fluid and preventing the fluid from overflowing.

[0065] In one embodiment, a negative pressure box 5 is also provided below the support plate 2. The negative pressure box 5 is connected to the inner side of the flow equalization structure 4 through a negative pressure port 51, providing a negative pressure environment inside the flow equalization structure 4. The negative pressure box 5 is located below the support plate 2, which facilitates full avoidance of the structure above, and is used to collect the fluid inside the flow equalization structure 4. Specifically, the rotating shaft of the support plate 2 extends downward and is rotatably connected to the bottom wall of the box body 14. The negative pressure box 5 can be configured as an annular box structure surrounding the outer periphery of the rotating shaft, utilizing the internal space for fluid collection.

[0066] For large-size wafers 6 (diameter ≥ 300mm) of 12 inches or larger, the above-mentioned wafer cleaning device has the characteristics of wider fluid coverage and larger fluid volume during use. By setting a negative pressure box 5 at the bottom of the carrier plate 2 to create a negative pressure state inside the uniform flow structure 4, the negative pressure environment also increases the adsorption effect of the hollow 43, which is conducive to meeting the need for a larger range and larger volume of fluid to be discharged under high speed in the cleaning scenario of large-size wafers 6, avoiding the risk of fluid spillage, and improving the adaptability and versatility of the device for wafers 6 of different sizes.

[0067] In one embodiment, the flow area of ​​the cutout 43 on the vertical sidewall 41 is larger than that of the cutout 43 on the inner edge 42, and is 1.5-3 times larger. During the wafer 6 cleaning process, the fluid above the uniform flow structure 4 is guided into its interior by the cutout 43 on the inner edge 42, preventing all the fluid from being tangentially thrown to the inner wall of the upper baffle ring 3 under centrifugal force. In addition, the fluid that is not guided into the uniform flow structure 4 flows downward from the gap between the uniform flow structure 4 and the upper baffle ring 3, and gradually flows into the gap 11 between the upper baffle ring 3 and the lower baffle ring 1. To prevent the fluid from continuing to flow into the gap 11, the flow area of ​​the cutout 43 on the vertical sidewall 41 is 1.5 to 3 times that of the cutout 43 on the inner edge 42. Under high rotational speed, the wafer 6 can preferentially and efficiently guide the fluid at the gap 11 into the uniform flow structure 4 using the cutout 43 on the vertical sidewall 41 with its larger flow area. The cutout 43 on the vertical sidewall 41 has a stronger suction and conduction capacity than the cutout 43 on the inner edge 42, which can enhance the fluid interception capacity and make it difficult for high-pressure fluid to overflow from the gap 11.

[0068] For example, when the flow area of ​​the hollow 43 on the vertical sidewall 41 is 2.5 times that of the flow area of ​​the hollow 43 on the inner edge 42, more than 90% of the fluid in the gap 11 can be guided under negative pressure, effectively solving the problem of fluid overflow at high speed.

[0069] While the perforations 43 on the vertical sidewall 41 and the perforations 43 on the inner edge 42 are distributed alternately, they do not overlap in the circumferential direction to avoid weakening each other's guiding ability for the fluid. If the perforations 43 on the vertical sidewall 41 and the inner edge 42 overlap in the circumferential direction or are too close together, it will cause the superposition interference of the flow field and the coupling effect of energy dissipation. This will cause the local flow fields (such as negative pressure fields and tangential flow channels) formed by each perforation 43 during the guiding or suction process to permeate and superimpose with each other, resulting in turbulent fluid flow path and attenuation of pressure gradient. This will then produce a coupling attenuation of guiding or suction efficiency, ultimately weakening the uniform flow effect and overflow prevention effect of the uniform flow structure 4.

[0070] In some embodiments, the circumferential angle of each cutout 43, that is, the circumferential coverage angle, is 10°-20°, for example, it can be set to 15°. This angle design ensures that the suction areas radiated by adjacent cutouts 43 do not overlap or interfere with each other, and can form a complementary effect to achieve full circumferential coverage and avoid suction blind spots. If the angle is too large, such as greater than 20°, it will cause the suction load of a single cutout 43 to be too large, and the pressure will not be released in time; if the angle is too small, such as less than 15°, it will increase the number of cutouts 43, resulting in a complex structure and increased cost.

[0071] The above structural design utilizes the vertical sidewall 41 to guide a large amount of fluid and the inner edge 42 to guide a small amount of fluid, achieving effective guidance and collection of fluid near the gap 11, improving fluid discharge efficiency, and preventing fluid from overflowing through the gap 11. At the same time, the large flow area can preferentially guide the high-pressure fluid at the gap 11, avoiding local fluid concentration that could cause pressure distortion on the inner wall of the lower baffle ring 1, further preventing the gap 11 from enlarging due to deformation of the lower baffle ring 1, and thus effectively preventing fluid spillage.

[0072] In one embodiment, an inner baffle ring 12 is also provided on the inner side of the lower baffle ring 1. The inner baffle ring 12 is located on the outer periphery of the negative pressure box 5, and its extension height is less than that of the lower baffle ring 1. This can effectively avoid the negative pressure port 51 and prevent interference with the flow field. A receiving cavity 13 is formed between the inner baffle ring 12 and the lower baffle ring 1. The flow equalization structure 4 is located in the receiving cavity 13. The lower edge of the flow equalization structure 4 is provided with a liquid passage hole 44 for liquid to pass through. The liquid gathers towards the lower inner side of the flow equalization structure 4 after passing through the liquid passage hole 44.

[0073] During the cleaning process of wafer 6, the fluid ejected flows downwards along the inner walls of the upper baffle ring 3 and the lower baffle ring 1 into the gap between the inner baffle ring 12 and the lower baffle ring 1, and then enters the uniform flow structure 4 through the liquid hole 44, accumulating and collecting at the bottom of the receiving cavity 13. A lower base 15 can be set at the bottom of the housing 14, with the inner baffle ring 12 and the lower baffle ring 1 uniformly set on the lower base 15. The top wall of the base forms the bottom wall of the receiving cavity 13. A drain pipe can be set below the lower base 15, and a valve can be installed on the drain pipe to facilitate the periodic discharge of liquid from the receiving cavity 13.

[0074] Furthermore, to improve the flow performance of the liquid, the bottom wall of the receiving cavity 13 is designed as an arc-shaped structure, and the bottom wall of the receiving cavity 13 forms an arc transition with both the inner baffle ring 12 and the lower baffle ring 1. The liquid passage hole 44 is located at the higher point of the arc-shaped structure, and the liquid can flow along the arc-shaped slope into the uniform flow structure 4. At this time, the accumulated liquid has a large height difference with the negative pressure port 51 of the negative pressure box 5, which prevents the accumulated liquid from being sucked into the interior by the negative pressure of the negative pressure box 5 and causing equipment failure.

[0075] The aforementioned wafer cleaning device is specifically designed for the high-speed and high-contaminant control precision requirements of advanced processes below 28nm. Through the coordinated design of the distribution of the cutouts 43 and parameters such as area ratio, it solves the problem of tangential fluid overflow that traditional devices cannot handle, effectively ensuring the processing quality of wafer 6.

[0076] A second aspect of this application provides a wafer cleaning method, which uses a wafer cleaning device to clean a wafer 6, including the following steps: rotating and cleaning the wafer 6, using a flow equalization structure 4 to equalize the fluid in the upper baffle ring 3, and guiding the fluid out from below the support plate 2 through a cutout 43 to prevent the fluid from overflowing from below the upper baffle ring 3 due to circumferential pressure distortion and pressure pulsation.

[0077] In this method, the wafer rotation speed needs to be adapted to the requirements of advanced processes below 28nm. At high rotation speeds of 6000rpm or higher, the size and number of grippers 21 increase, and the combined effect with the high rotation speed causes the fluid to overflow from the gap 11 at a high tangential velocity. During the wafer 6 cleaning process, the upper baffle ring 3 is initially in a low position, which facilitates the mounting of the wafer 6 to be processed onto the carrier disk 2. Then, the upper baffle ring 3 moves upward and covers the outer periphery of the carrier disk 2, and the carrier disk 2 drives the wafer 6 to rotate, spraying the cleaning fluid onto the surface of the wafer 6. During this process, the flow equalization structure 4 is used to equalize the fluid ejected from the carrier disk 2 and the wafer 6, preventing the formation of a high-pressure zone inside the upper baffle ring 3. At the same time, the perforation 43 guides the fluid into the flow equalization structure 4, preventing the fluid from overflowing outward from the gap 11 between the upper baffle ring 3 and the lower baffle ring 1, thereby preventing the fluid from flowing back to the surface of the wafer 6 and causing secondary contamination.

[0078] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and such modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A wafer cleaning apparatus, characterized in that, include: A carrier disk is used to support the rotation of the wafer; A lower retaining ring is disposed on the lower outer side of the bearing plate; The upper retaining ring is disposed on the upper side of the outer side of the bearing plate, and a gap is formed between it and the lower retaining ring; A flow equalization structure is disposed below the inner side of the upper baffle ring. The flow equalization structure is a circumferential ring-shaped shell structure, which is used to equalize the radial pressure inside the upper baffle ring and prevent high-pressure fluid from diffusing into the gap. The flow equalization structure is also provided with a hollow for guiding the fluid into its interior.

2. The wafer cleaning apparatus as described in claim 1, characterized in that, The uniform flow structure consists of a vertical sidewall and an inner edge extending inward from its top, and the cutout is formed in the vertical sidewall and / or the inner edge.

3. The wafer cleaning apparatus as described in claim 2, characterized in that, Both the vertical sidewall and the inner edge are provided with the hollowed-out holes. The hollowed-out holes on the vertical sidewall and the hollowed-out holes on the inner edge are elongated holes. The elongated holes on the vertical sidewall are set at an angle to the axial direction of the flow uniform structure, and the extension direction of the elongated holes on the inner edge is set to intersect the radial direction of the flow uniform structure.

4. The wafer cleaning apparatus as described in claim 3, characterized in that, An annular guide plate is provided on the inner peripheral wall of the flow uniform structure. The annular guide plate is located below the hollowed-out vertical side wall. The annular guide plate extends circumferentially along the flow uniform structure and is gradually inclined downward from the outer periphery of the flow uniform structure to the axis of the flow uniform structure.

5. The wafer cleaning apparatus according to any one of claims 1-4, characterized in that, It also includes a housing, in which the carrier plate, the upper baffle ring, the lower baffle ring and the flow equalization structure are all disposed, and the side or top of the housing is provided with an opening for feeding or taking out the wafer.

6. The wafer cleaning apparatus as described in claim 5, characterized in that, A negative pressure box is also provided below the bearing plate. The negative pressure box is connected to the inner side of the uniform flow structure through a negative pressure port to enhance the adsorption effect of the hollowed-out structure.

7. The wafer cleaning apparatus as described in claim 6, characterized in that, The inner side of the lower baffle ring is also provided with an inner baffle ring. The extension height of the inner baffle ring is less than the extension height of the lower baffle ring, and a receiving cavity is formed between the inner and lower baffle rings. The flow equalization structure is located in the receiving cavity, and the lower edge of the flow equalization structure is provided with a liquid passage hole for liquid to pass through and collect.

8. The wafer cleaning apparatus as described in claim 7, characterized in that, The bottom of the housing is provided with a lower base, and both the inner retaining ring and the lower retaining ring are provided on the lower base. The top wall of the base forms the receiving cavity.

9. The wafer cleaning apparatus as described in claim 8, characterized in that, A drain pipe is provided below the lower base, and a valve is provided on the drain pipe to discharge the liquid in the receiving cavity.

10. A wafer cleaning method, comprising cleaning a wafer using the wafer cleaning apparatus according to any one of claims 1-9, characterized in that, Includes the following steps: The wafer is rotated and cleaned, and the fluid in the upper baffle is uniformly distributed using the uniform flow structure. The fluid is then guided out from below the carrier disk through a perforation.

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