Air purification equipment applied to wafer detection and wafer detection system

Abstract

The invention provides air purification equipment applied to wafer detection and a wafer detection system.The air purification equipment comprises a rack and an air supply part, an outer protection cavity, a light path cavity and a detection cavity are formed in the rack, the light path cavity and the detection cavity are formed in the outer protection cavity, and the air supply part communicates with the outer protection cavity, the light path cavity and the detection cavity; the air pressure in the detection cavity is greater than the air pressure in the light path cavity, and the air pressure in the light path cavity is greater than the air pressure in the outer protection cavity. The light path cavity and the detection cavity are arranged in the outer protection cavity, and a gradient air pressure system in which the air pressure of the detection cavity is higher than that of the light path cavity and the air pressure of the light path cavity is higher than that of the outer protection cavity is constructed, so that multiple protection barriers are formed, external pollutants are effectively prevented from invading a core working area, and the cleanliness control effect is improved; and the requirement of nanoscale wafer detection on the environment is met.

Description

Technical Field

[0001] This application belongs to the field of wafer inspection technology, specifically relating to an air purification device and a wafer inspection system for wafer inspection. Background Technology

[0002] As semiconductor technology enters the nanoscale era, the accuracy requirements for wafer defect detection have been upgraded from the micrometer level to the nanometer level. Temperature fluctuations and residual microparticles in the environment have an increasingly significant impact on detection accuracy, becoming key factors restricting detection accuracy.

[0003] To meet cleanliness control requirements, existing technologies generally employ a cleanliness control scheme where FFUs blow air from the top of the entire chamber and exhaust it centrally from the bottom. This vertical airflow carries out contaminants to maintain chamber cleanliness. However, when there are obstructions such as optical components or protective structures above the detection chamber, the vertical airflow can easily create dead zones, preventing contaminants from being effectively removed. This results in poor cleanliness control in the obstructed areas, making it difficult to meet the stringent cleanliness requirements of nanoscale detection. Summary of the Invention

[0004] Therefore, the technical problem to be solved by this application is to provide an air purification device and a wafer inspection system for wafer inspection, which can improve the cleanliness control effect and meet the requirements of nanoscale inspection for a clean environment.

[0005] To address the aforementioned problems, a first aspect of this application provides an air purification device for wafer inspection, comprising a frame and an air supply unit. The frame contains an outer protective cavity, an optical path cavity, and a detection cavity. The optical path cavity and the detection cavity are disposed within the outer protective cavity. The air supply unit is connected to the outer protective cavity, the optical path cavity, and the detection cavity respectively, to supply airflow into the outer protective cavity, the optical path cavity, and the detection cavity respectively. The air pressure in the detection cavity is greater than the air pressure in the optical path cavity, and the air pressure in the optical path cavity is greater than the air pressure in the outer protective cavity.

[0006] Optionally, the air supply unit includes an air purification unit, the air inlet of which is connected to an air source, and the air outlet of which is connected to the outer protective cavity, the optical path cavity, and the detection cavity, respectively.

[0007] Optionally, the air purification unit is disposed at the top of the frame and is connected to the outer protective cavity to allow airflow to be introduced into the outer protective cavity in a vertically downward direction.

[0008] Optionally, the airflow introduced into the outer protective cavity via the air purification unit flows uniformly downward at a speed of 0.4 m / s to 0.5 m / s, and the outer protective cavity maintains a positive pressure of 1.8 Pa to 2.2 Pa relative to the external space of the frame.

[0009] Optionally, the air supply unit further includes a blower and air collector box, which is connected to the air purification unit. The blower and air collector box is connected to the optical path cavity through a first pipe, and the blower and air collector box is connected to the detection cavity through a second pipe.

[0010] Optionally, the optical path cavity is provided with a first air inlet and a first air outlet on its cavity wall. The first air inlet and the first air outlet are respectively provided on different cavity walls of the optical path cavity, and the first air inlet is connected to the first pipeline.

[0011] Optionally, the first air inlet and the first air outlet are arranged opposite each other in the horizontal direction to form a horizontal unidirectional flow field.

[0012] Optionally, the first exhaust port is provided with a first exhaust mechanism, which is used to extract the airflow in the optical path cavity.

[0013] Optionally, the air volume accuracy of the first exhaust mechanism is ±3%.

[0014] Optionally, the static pressure in the optical path cavity is ≤50Pa, the airflow rate in the optical path cavity is 1150m³ / h to 1250m³ / h, and the airflow velocity in the optical path cavity is 0.27m / s to 0.33m / s.

[0015] Optionally, the detection cavity wall is provided with a second air inlet and a second air outlet. The second air inlet is connected to the second pipeline. The second air inlet is provided with a perforated plate damping so that the airflow in the second pipeline is discharged through the perforated plate damping to form a lateral laminar flow field on the wafer surface.

[0016] Optionally, the turbulence of the airflow discharged via the perforated plate damping is ≤15%, and the airflow velocity of the transverse laminar flow field is 0.23 m / s to 0.27 m / s.

[0017] Optionally, the second exhaust port is provided with a second exhaust mechanism, which is used to create a negative pressure of 90Pa to 110Pa at the second exhaust port to extract the airflow in the detection chamber.

[0018] Optionally, the cavity walls of the optical path cavity and the detection cavity are provided with overcurrent gaps, and the optical path cavity is connected to the detection cavity through the overcurrent gaps. The tolerance of the overcurrent gaps is ±1mm.

[0019] Optionally, the total flow rate of the airflow in the detection cavity is L, and 14%L to 16%L of the airflow in the detection cavity is introduced into the optical path cavity through the flow gap; the pressure difference gradient between the detection cavity and the optical path cavity is 1.3Pa / m to 1.7Pa / m.

[0020] Optionally, the detection cavity maintains a positive pressure of 4.5 Pa to 5.5 Pa relative to the optical path cavity, and the optical path cavity maintains a positive pressure of 2.7 Pa to 3.3 Pa relative to the outer protective cavity.

[0021] Optionally, the first pipeline is a seamless 316L stainless steel pipe with a surface roughness Ra≤0.8μm, and / or the second pipeline is a seamless 316L stainless steel pipe with a surface roughness Ra≤0.8μm.

[0022] Optionally, the air supply unit includes a honeycomb damping structure, which is disposed on the upstream side of the air purification unit. The opening ratio of the honeycomb damping structure is ≥75%, the pressure loss of the airflow passing through the honeycomb damping structure is ≤30Pa, the airflow velocity at the air inlet of the honeycomb damping structure is ≥1.2m / s, and the airflow velocity at the air outlet of the honeycomb damping structure is ≤0.3m / s.

[0023] Optionally, the air purification device includes a control unit, a first differential pressure sensor is disposed between the outer protective cavity and the optical path cavity, and a second differential pressure sensor is disposed between the optical path cavity and the detection cavity. The first differential pressure sensor and the second differential pressure sensor are respectively connected to the control unit. The air purification device includes an exhaust unit, which is connected to the outer protective cavity, the optical path cavity, and the detection cavity. The exhaust unit is disposed at the bottom of the frame. The first pipe, the second pipe, and the exhaust unit are respectively provided with proportional adjustment mechanisms, and the proportional adjustment mechanisms are connected to the control unit.

[0024] A second aspect of this application provides a wafer inspection system, including a wafer inspection device and an air purification device as described above for wafer inspection, wherein the wafer inspection device is connected to the air purification device.

[0025] The air purification device and wafer inspection system provided in the embodiments of this application, which are applied to wafer inspection, form multiple protective barriers by setting the optical path cavity and the detection cavity inside the outer protective cavity and constructing a gradient air pressure system in which the air pressure in the detection cavity is higher than that in the optical path cavity and the air pressure in the optical path cavity is higher than that in the outer protective cavity. This effectively blocks external pollutants from entering the core working area, improves the cleanliness control effect, and adapts to the environmental requirements of nanoscale wafer inspection. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of the air purification device according to an embodiment of this application from one perspective; Figure 2 This is a schematic diagram of the air purification device according to another perspective of an embodiment of this application; Figure 3 This is a schematic diagram of the detection cavity from one perspective, according to an embodiment of this application.

[0027] The reference numerals in the attached figures are as follows: 1. Frame; 2. Air supply section; 21. Air blower and air collection box; 3. Optical path cavity; 31. First air inlet; 32. First air outlet; 4. Detection cavity; 41. Second air inlet; 42. Second air outlet; 5. Exhaust section. Detailed Implementation

[0028] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not 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.

[0029] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0030] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection 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 according to the specific circumstances.

[0031] The embodiments of this application are described below with reference to the accompanying drawings. It should be understood that the embodiments described herein are for illustration and explanation only and are not intended to limit this application.

[0032] See also Figures 1 to 3 As shown, according to a first aspect of the embodiments of this application, an air purification device for wafer inspection is provided, including a frame 1 and an air supply unit 2. The frame 1 is provided with an outer protective cavity, an optical path cavity 3 and a detection cavity 4. The optical path cavity 3 and the detection cavity 4 are disposed in the outer protective cavity. The air supply unit 2 is connected to the outer protective cavity, the optical path cavity 3 and the detection cavity 4 respectively, so as to introduce airflow into the outer protective cavity, the optical path cavity 3 and the detection cavity 4 respectively. The air pressure in the detection cavity 4 is greater than the air pressure in the optical path cavity 3, and the air pressure in the optical path cavity 3 is greater than the air pressure in the outer protective cavity.

[0033] By setting the optical path cavity 3 and the detection cavity 4 inside the outer protective cavity, and constructing a gradient air pressure system in which the air pressure of the detection cavity 4 is higher than that of the optical path cavity 3 and the air pressure of the optical path cavity 3 is higher than that of the outer protective cavity, multiple protective barriers are formed, effectively preventing external pollutants from entering the core working area, improving the cleanliness control effect, and adapting to the environmental requirements of nanoscale wafer detection.

[0034] The air supply unit 2 is connected to the outer protective cavity, the optical path cavity 3, and the detection cavity 4, respectively. It can independently supply airflow into the outer protective cavity, the optical path cavity 3, and the detection cavity 4. Through precise control of the airflow supply, a pressure gradient is formed within the outer protective cavity, the optical path cavity 3, and the detection cavity 4. The detection cavity 4 has the highest pressure, the optical path cavity 3 has a medium pressure, and the outer protective cavity has the lowest pressure. The pressure in the outer protective cavity is higher than the external ambient pressure.

[0035] Specifically, the frame 1 is roughly a cuboid frame structure. The air supply unit 2 is located at the top of the frame 1 and is connected to the top of the outer protective cavity, allowing airflow to enter the outer protective cavity from top to bottom. The outer protective cavity is a cavity structure formed inside the frame 1, and the optical path cavity 3 and the detection cavity 4 are cavity structures separated inside the outer protective cavity, that is, the optical path cavity 3 and the detection cavity 4 are located inside the outer protective cavity.

[0036] The air supply unit 2 includes an air purification unit. The air inlet of the air purification unit is connected to the air source, and the air outlet of the air purification unit is connected to the outer protective cavity, the optical path cavity 3, and the detection cavity 4, respectively.

[0037] The air purification unit provides clean airflow to the outer protective cavity, optical path cavity 3, and detection cavity 4 respectively, ensuring that the air entering these three cavities is purified and preventing the introduction of pollutants by unpurified air. Simultaneously, the unified air supply through a single air purification unit simplifies the air supply system structure, reduces the need for independent purification units, lowers equipment costs and space requirements, and adapts to the miniaturization requirements of the equipment.

[0038] The air purification unit has an intake end connected to an air source to obtain raw gas, and an exhaust end connected to the outer protective cavity, optical path cavity 3 and detection cavity 4 respectively. After the raw air is purified by the air purification unit, it is delivered to the outer protective cavity, optical path cavity 3 and detection cavity 4 respectively to provide clean airflow.

[0039] The air purification unit includes a U17-grade high-efficiency filter with a filtration efficiency of ≥99.999995%@0.1μm.

[0040] The air purification unit is located at the top of the frame 1 and is connected to the outer protective cavity to allow airflow to enter the outer protective cavity in a vertically downward direction.

[0041] By placing the air purification unit at the top of the frame 1, the airflow can be directed vertically downwards into the outer protective cavity, forming a vertical airflow that covers the entire area of ​​the outer protective cavity. This effectively removes suspended pollutants from the cavity, and the uniform coverage of the vertical airflow across the entire protective cavity ensures that the cleanliness of each area of ​​the outer protective cavity is uniform, providing a stable external clean environment for the internal optical path cavity 3 and the detection cavity 4.

[0042] The air purification unit is installed at the top of the frame 1. One exhaust end of the air purification unit can be connected to the outer protective cavity. When working, the clean airflow output by the air purification unit is continuously introduced into the outer protective cavity in a vertically downward direction, so that the airflow forms a top-to-bottom flow path in the protective cavity.

[0043] Specifically, in one embodiment, the air purification unit may include multiple exhaust ends, one of which is directly connected to the outer protective cavity, and the other exhaust ends are connected to the optical path cavity 3 and the detection cavity 4 through a pipeline.

[0044] The airflow introduced into the outer protective cavity through the air purification unit flows downward uniformly at a speed of 0.4 m / s to 0.5 m / s, and the outer protective cavity maintains a positive pressure of 1.8 Pa to 2.2 Pa relative to the external space of the frame 1.

[0045] By maintaining a uniform downward airflow velocity of 0.4 m / s to 0.5 m / s within the outer protective cavity, contaminants can be effectively carried away, maintaining the ISO Class 2 microenvironment control of the outer protective cavity. This also prevents excessively high airflow velocities from disturbing the internal cavity. Maintaining a positive pressure of 1.8 Pa to 2.2 Pa relative to the external space of the frame 1 within the outer protective cavity prevents the infiltration of unpurified external air, further enhancing the protective effect of the outer protective cavity and providing a stable and clean external environment for the internal optical path cavity 3 and detection cavity 4.

[0046] Air purification equipment is usually installed in the clean room, and the outer protective cavity maintains a basic positive pressure of 2±0.2Pa relative to the clean room.

[0047] The bottom of the frame 1 can be provided with an exhaust section 5, through which the airflow entering the outer protective cavity is discharged, thereby ensuring that the airflow in the outer protective cavity flows downward evenly.

[0048] In one embodiment, the airflow entering the outer protective cavity flows uniformly downward at a speed of 0.45 m / s, and the outer protective cavity maintains a positive pressure of 2 Pa relative to the external space of the frame 1.

[0049] like Figure 2 As shown, the air supply unit 2 also includes a blower and air collector box 21, which is connected to the air purification unit. The blower and air collector box 21 is connected to the optical path cavity 3 through the first pipe and to the detection cavity 4 through the second pipe.

[0050] The clean airflow output from the air purification unit is centrally distributed by the air blower and air collection box 21, and then the airflow is delivered to the optical path cavity 3 and the detection cavity 4 through the first pipe and the second pipe respectively, realizing independent control of the air supply to the optical path cavity 3 and the detection cavity 4. The air supply volume can be precisely adjusted according to the cleanliness and airflow requirements of the optical path cavity 3 and the detection cavity 4, improving the flexibility and targeting of the air supply system, while simplifying the pipe connection structure and facilitating system maintenance.

[0051] The blower and air collector box 21 is connected to the exhaust end of the air purification unit, so that it can receive the purified clean airflow. The blower and air collector box 21 is connected to the optical path cavity 3 through the first pipe and to the detection cavity 4 through the second pipe. After the clean airflow is distributed by the blower and air collector box 21, it is accurately delivered to the optical path cavity 3 and the detection cavity 4 through the two pipes respectively.

[0052] The first and second pipelines are independent of each other. The air inlet ends of the first and second pipelines are connected to the air blower box 21, and the exhaust end of the first pipeline is connected to the cavity wall of the optical path cavity 3 and communicates with the internal space of the optical path cavity 3. The exhaust end of the second pipeline is connected to the cavity wall of the detection cavity 4 and communicates with the internal space of the detection cavity 4.

[0053] The optical path cavity 3 has a first air inlet 31 and a first air outlet 32 ​​on its cavity wall. The first air inlet 31 and the first air outlet 32 ​​are respectively located on different cavity walls of the optical path cavity 3. The first air inlet 31 is connected to the first pipeline.

[0054] By setting a first air inlet 31 and a first air outlet 32 ​​on the cavity wall of the optical path cavity 3, the airflow can form a complete flow path within the optical path cavity 3. By placing the first air inlet 31 and the first air outlet 32 ​​on different cavity walls of the optical path cavity 3, airflow stagnation can be reduced, ensuring that contaminants generated within the optical path cavity 3 can be promptly removed. Simultaneously, the first air inlet 31 is connected to the first duct, ensuring efficient input of clean airflow, improving the stability of the cleanliness within the optical path cavity 3, and meeting the clean environment requirements for the operation of optical components.

[0055] The optical path cavity 3 has a first air inlet 31 and a first air outlet 32 ​​on its cavity wall. The first air inlet 31 and the first air outlet 32 ​​are located on different vertically extending cavity walls of the optical path cavity 3, that is, on different side walls of the optical path cavity 3.

[0056] Specifically, in one embodiment, the optical path cavity 3 is generally a cuboid cavity structure, the first air inlet 31 is opened on one side wall, and the first air outlet 32 ​​can be opened on the opposite side wall or on the adjacent side wall.

[0057] like Figure 1 As shown, in one embodiment, the first air inlet 31 and the first air outlet 32 ​​are arranged opposite each other in the horizontal direction to form a horizontal unidirectional flow field.

[0058] By setting the first air inlet 31 and the first air outlet 32 ​​opposite each other in the horizontal direction, the airflow can form a horizontal unidirectional flow field in the optical path cavity 3. The airflow direction is stable and there is no backflow, which can fully cover the optical path transmission area, effectively remove suspended particles around the optical components, avoid pollutants from depositing on the optical path, ensure the accuracy of optical detection, and solve the problem of vertical airflow being easily blocked.

[0059] The first air inlet 31 and the first air outlet 32 ​​are horizontally opposite each other on the cavity wall of the optical path cavity 3. After the clean airflow enters the optical path cavity 3 from the first air inlet 31, it flows radially to the opposite first air outlet 32 ​​in the horizontal direction, forming a stable horizontal unidirectional flow field inside the optical path cavity 3.

[0060] Specifically, such as Figure 1 As shown, in one embodiment, the first air inlet 31 can be disposed on the right cavity wall of the optical path cavity 3, and the first air outlet 32 ​​can be disposed on the left cavity wall of the optical path cavity 3. The first air inlet 31 and the first air outlet 32 ​​are at least partially opposite to each other in the horizontal direction.

[0061] The first exhaust vent 32 is equipped with a first exhaust mechanism, which is used to extract the airflow inside the optical path cavity 3.

[0062] By installing a first exhaust mechanism at the first exhaust vent 32, the airflow within the optical path cavity 3 can be actively accelerated, enhancing airflow flow and ensuring that pollutants are quickly carried away from the optical path cavity 3, preventing pollutant retention. Simultaneously, the exhaust function of the first exhaust mechanism can also help maintain the air pressure within the optical path cavity 3, maintaining the pressure difference between the optical path cavity 3 and the outer protective cavity, as well as between the optical path cavity 3 and the detection cavity 4. This ensures the overall air pressure gradient of the air purification equipment, guarantees the stability of the air pressure system, and further improves the cleanliness control effect of the optical path cavity 3.

[0063] A first exhaust mechanism is installed at the first exhaust port 32. The exhaust direction of the first exhaust mechanism is towards the outside of the optical path cavity 3. When the first exhaust mechanism is working, it generates a suction force to draw the airflow in the optical path cavity 3 out from the first exhaust port 32, thereby realizing the active discharge of the airflow in the optical path cavity 3 and promoting the flow and renewal of airflow in the cavity.

[0064] Specifically, the first ventilation mechanism is an adjustable-speed fan.

[0065] The air volume accuracy of the first exhaust mechanism is ±3%, which enables the exhaust mechanism to have high air volume accuracy and accurately control the airflow discharge in the optical path cavity 3, ensuring that the airflow is stable within the set range, avoiding airflow field instability due to air volume fluctuations, and thus maintaining the pressure difference between the optical path cavity 3 and the outer protective cavity, as well as between the optical path cavity 3 and the detection cavity 4.

[0066] During operation, it can operate stably according to the set air volume parameters, accurately control the airflow rate extracted from the optical cavity 3, avoid excessive fluctuations in air volume, and ensure the stability of the airflow system.

[0067] The static pressure inside the optical path cavity 3 is ≤50Pa, the airflow rate inside the optical path cavity 3 is 1150m³ / h to 1250m³ / h, and the airflow velocity inside the optical path cavity 3 is 0.27m / s to 0.33m / s.

[0068] By controlling the airflow of the first exhaust mechanism and the air intake of the optical cavity 3, the static pressure inside the optical cavity 3 is kept to be ≤50Pa, the airflow rate inside the optical cavity 3 is 1150m³ / h to 1250m³ / h, and the airflow velocity inside the optical cavity 3 is 0.27m / s to 0.33m / s. This creates a low static pressure, stable flow rate and velocity airflow environment inside the optical cavity 3. This avoids the impact of excessive static pressure on the optical components and ensures efficient removal of contaminants through stable airflow rate and velocity. It also adapts to the working characteristics of optical path transmission, providing a clean and stable environment for optical detection and ensuring detection accuracy.

[0069] In this process, the airflow distributes the incoming air through the Venturi effect, converting it into uniform clean air with low static pressure and high flow rate, forming a horizontal unidirectional flow field.

[0070] Specifically, in one embodiment, the static pressure in the optical cavity 3 is 50 Pa, the airflow rate in the optical cavity 3 is 1200 m³ / h, and the airflow velocity in the optical cavity 3 is 0.3 m / s.

[0071] Within the optical path cavity 3, laminar flow covers the entire optical transmission area. After passing through the working area of ​​the optical components, clean air is efficiently exhausted by the first exhaust mechanism. Dynamic airflow organization can remove suspended particles generated within the cavity in real time, ensuring that the optical path is always in a clean environment higher than ISO Class 1.

[0072] The detection chamber 4 has a second air inlet 41 and a second air outlet 42 on its cavity wall. The second air inlet 41 is connected to the second pipeline. The second air inlet 41 is equipped with a perforated plate damping so that the airflow in the second pipeline is discharged through the perforated plate damping to form a transverse laminar flow field on the wafer surface.

[0073] By setting a perforated plate damper at the second air inlet 41 of the detection chamber 4, the airflow is discharged after being damped, which can effectively homogenize the airflow velocity and form a stable transverse laminar flow field on the wafer surface. This avoids airflow turbulence from disturbing the wafer surface. At the same time, the transverse laminar flow can fully cover the wafer detection area, efficiently remove tiny particles in the area, and prevent contaminant deposition from affecting detection accuracy. This meets the requirements of airflow stability and cleanliness for nanoscale wafer detection.

[0074] The detection chamber 4 has a second air inlet 41 and a second air outlet 42 on its cavity wall. The second air inlet 41 is connected to the end of the second pipeline away from the air blower box 21. A perforated plate damping component is installed at the second air inlet 41. The clean airflow delivered by the second pipeline needs to be treated by the pressure equalization and rectification of the perforated plate damping before being discharged into the detection chamber 4, and finally forming a stable transverse laminar flow field on the wafer surface.

[0075] Specifically, when the clean airflow delivered by the second pipeline reaches the second air inlet 41, it first contacts the perforated plate damper. Because the perforated plate damper is densely covered with uniform micropores, the airflow is divided into small airflow streams as it passes through the micropores. Since the micropores are of uniform diameter and evenly distributed, the airflow is constrained by uniform resistance as it passes through the micropores, the flow velocity is homogenized, and the airflow velocity in each area tends to be consistent, achieving a pressure equalization effect. The second air inlet 41 is located at the top of the detection chamber 4 and is connected to the perforated plate damper. The perforated plate damper is vertically positioned with a horizontal airflow direction, thus forming a stable transverse laminar flow field on the horizontally placed wafer surface. This efficiently removes tiny particles from the wafer surface without disturbing the wafer due to airflow turbulence, ensuring the accuracy of nanoscale detection.

[0076] The turbulence intensity of the airflow discharged through the perforated plate damping is ≤15%, and the airflow velocity in the transverse laminar flow field is 0.23 m / s to 0.27 m / s.

[0077] By controlling the turbulence of the airflow discharged through the perforated plate to no more than 15%, a lower turbulence can prevent airflow disturbances from interfering with the wafer surface microstructure and the detection process. By controlling the airflow velocity of the transverse laminar flow field to 0.23 m / s to 0.27 m / s, a stable airflow velocity can ensure that contaminants are continuously and efficiently removed from the wafer surface, ensuring uniform cleanliness inside detection chamber 4 and further improving the accuracy of the detection results.

[0078] The turbulence of the discharged airflow and the airflow rate of the transverse laminar field can be controlled by selecting an appropriate perforated plate damper.

[0079] The second exhaust port 42 is equipped with a second exhaust mechanism, which is used to create a negative pressure of 90Pa to 110Pa at the second exhaust port 42 to extract the airflow in the detection chamber 4.

[0080] By setting a second exhaust mechanism at the second exhaust port 42 and forming a negative pressure of 90Pa to 110Pa, the airflow carrying contaminants in the detection chamber 4 can be stably extracted, accelerating the airflow circulation and renewal, and preventing contaminants from lingering in the detection chamber 4. At the same time, the negative pressure environment can help maintain the air pressure gradient between the detection chamber 4 and the optical path chamber 3, ensuring a stable flow of clean airflow from the detection chamber 4 to the optical path chamber 3, further enhancing the cleanliness and protection effect of the detection chamber 4, and ensuring that wafer detection is not affected by contaminants.

[0081] The second exhaust mechanism has its exhaust direction facing the outside of the detection chamber 4. When working, it can create a negative pressure environment of 90Pa to 110Pa at the second exhaust port 42. Under the adsorption effect of the negative pressure, the airflow in the detection chamber 4 and the pollutants it carries are quickly extracted, realizing the efficient replacement of the airflow in the detection chamber 4.

[0082] An overcurrent gap is provided on the cavity wall of the optical path cavity 3 and the cavity wall of the detection cavity 4. The optical path cavity 3 is connected to the detection cavity 4 through the overcurrent gap, and the tolerance of the overcurrent gap is ±1mm.

[0083] A flow gap is set in the cavity walls of optical cavity 3 and detection cavity 4, and the tolerance is controlled to enable airflow communication between optical cavity 3 and detection cavity 4 through the flow gap, providing a channel for the formation and maintenance of pressure gradient. Precise control of the flow gap tolerance ensures stable and controllable airflow and avoids pressure imbalance caused by excessively large or small gaps.

[0084] The cavity wall of the optical path cavity 3 and the cavity wall of the detection cavity 4 are provided with a flow gap, so that the internal spaces of the optical path cavity 3 and the detection cavity 4 can be connected to each other through the flow gap. Since the air pressure in the detection cavity 4 is greater than the air pressure in the optical path cavity 3, the airflow in the detection cavity 4 can flow into the optical path cavity 3 through the flow gap.

[0085] Specifically, through the flow gap between the optical path cavity 3 and the detection cavity 4, a stable micro-positive pressure system between the detection cavity 4 and the optical path cavity 3 can be formed. Through the automatic pressure gradient compensation mechanism, the cleanliness of the detection cavity 4 is maintained at ISO Class 1 level.

[0086] The total flow rate of the airflow in the detection cavity 4 is L. 14%L to 16%L of the airflow in the detection cavity 4 is introduced into the optical path cavity 3 through the flow gap.

[0087] By allowing 14%L to 16%L of airflow from the detection cavity 4 to enter the optical path cavity 3 through the flow gap, a stable airflow supply is formed between the detection cavity 4 and the optical path cavity 3. This ensures that the clean airflow from the detection cavity 4 can continuously provide cleanliness for the optical path cavity 3, while also preventing excessive airflow loss from affecting the air pressure stability of the detection cavity 4. Through precise airflow distribution ratio, the air pressure gradient between the two cavities is further optimized, improving the overall cleanliness control effect and ensuring a clean environment for optical components and wafer inspection areas.

[0088] Specifically, in one embodiment, 15%L of airflow in the detection cavity 4 is introduced into the optical path cavity 3 through the flow gap.

[0089] The pressure gradient between the detection cavity 4 and the optical path cavity 3 is 1.3 Pa / m to 1.7 Pa / m.

[0090] By controlling the pressure gradient between the detection cavity 4 and the optical path cavity 3 within the range of 1.3 Pa / m to 1.7 Pa / m, a stable and moderate air pressure driving force can be formed. This ensures that the airflow flows smoothly from the detection cavity 4 to the optical path cavity 3. This avoids both excessively large pressure gradients that could cause excessively fast airflow and disturb the optical components or wafers, and insufficient pressure gradients that could not effectively block the diffusion of contaminants. This ensures the cleanliness level of the two core cavities and provides a reliable environmental basis for nanoscale detection. Specifically, in one embodiment, the pressure gradient between the detection cavity 4 and the optical path cavity 3 is 1.5 Pa / m.

[0091] The detection cavity 4 maintains a positive pressure of 4.5 Pa to 5.5 Pa relative to the optical path cavity 3, and the optical path cavity 3 maintains a positive pressure of 2.7 Pa to 3.3 Pa relative to the outer protective cavity. As described above, the outer protective cavity maintains a positive pressure of 1.8 Pa to 2.2 Pa relative to the external space of the frame 1.

[0092] By setting pressure gradients, a tiered protective barrier is formed, effectively blocking the penetration of external pollutants and upgrading the cleanliness level of the core work area from the initial ISO14644 Class 5 standard to Class 1.

[0093] Specifically, by constructing a progressively decreasing pressure gradient between the detection chamber 4, the optical path chamber 3, and the outer protective chamber, a multi-layered three-dimensional protective barrier is formed, effectively blocking the penetration of contaminants from the external environment and between chambers. The positive pressure design of the detection chamber 4 relative to the optical path chamber 3 prevents contaminants that may be generated in the optical path chamber 3 from spreading to the core detection area. At the same time, the positive pressure of the optical path chamber 3 relative to the outer protective chamber can prevent contaminants from the outer protective chamber and the external space from entering the optical path chamber 3. This dual protection ensures that the cleanliness level of the detection chamber 4 and the optical path chamber 3 is raised to the ISO Class 1 standard, meeting the clean environment requirements for nanoscale wafer detection.

[0094] The pressure inside the detection chamber 4 is consistently higher than that inside the optical path chamber 3, with the pressure difference between the two chambers maintained between 4.5 Pa and 5.5 Pa. Conversely, the pressure inside the optical path chamber 3 is higher than that inside the outer protective chamber, with the pressure difference maintained between 2.7 Pa and 3.3 Pa. This pressure gradient prevents contaminants from spreading from the outer protective chamber into the optical path chamber 3, and contaminants from the optical path chamber 3 into the detection chamber 4. Combined with the first and second exhaust ventilation structures, this system effectively blocks contaminants while ensuring stable airflow in the core working area, providing a clean environment for wafer inspection and optical component operation.

[0095] The first pipeline is a seamless 316L stainless steel pipe with a surface roughness Ra≤0.8μm, and / or the second pipeline is a seamless 316L stainless steel pipe with a surface roughness Ra≤0.8μm.

[0096] By using 316L grade stainless steel seamless pipes as the first and second pipelines, contaminants generated by the pipes themselves can be avoided. At the same time, the surface roughness is controlled to be no more than 0.8μm. Low surface roughness can reduce airflow resistance, prevent particulate matter from depositing on the inner wall of the pipe, and ensure that the airflow delivered to the optical path cavity 3 and detection cavity 4 is clean and uncontaminated, ensuring the cleanliness of the core area and meeting the stringent requirements of nanoscale detection for airflow delivery pipelines.

[0097] The air supply unit 2 includes a honeycomb damping structure, which is located on the upstream side of the air purification unit. The opening ratio of the honeycomb damping structure is ≥75%, the pressure loss of the airflow passing through the honeycomb damping structure is ≤30Pa, the airflow velocity at the air inlet of the honeycomb damping structure is ≥1.2m / s, and the airflow velocity at the air outlet of the honeycomb damping structure is ≤0.3m / s.

[0098] By setting a honeycomb damping structure with an opening ratio of no less than 75% and an airflow pressure loss of no more than 30 Pa, the airflow entering the air purification unit can be rectified and homogenized. This ensures that the airflow velocity at the inlet of the honeycomb damping structure is ≥1.2 m / s, and the airflow velocity at the outlet is ≤0.3 m / s. The high opening ratio ensures efficient airflow, while the low airflow pressure loss guarantees reasonable system energy consumption. The controlled flow velocity at the inlet and outlet prevents high-speed airflow from interfering with the airflow environment of subsequent purification units and chambers, effectively improving the purification efficiency of the air purification unit and providing stable and uniform clean airflow to each chamber, further optimizing the overall cleanliness control effect.

[0099] The honeycomb damping structure is positioned upstream of the air purification unit, within the flow channel before the airflow enters the unit, thus forming a series airflow channel with the unit. The honeycomb damping structure is a sheet-like or block-like structure adapted to the airflow channel, composed of numerous regularly arranged honeycomb micropores. These micropores can be hexagonal or circular, and they extend throughout the entire structure along the airflow direction. During installation, the edges of the honeycomb damping structure are tightly fitted to the inner wall of the airflow channel, ensuring that airflow can only pass through the internal honeycomb micropores without side leakage, while also ensuring a stable installation. Furthermore, the relatively small cross-sectional area of ​​the flow channel on the air inlet side of the honeycomb damping structure, combined with the airflow power supplied by the air supply unit 2, allows the airflow to maintain a high velocity upon entering the honeycomb damping structure, meeting the requirement that the airflow velocity at the air inlet is not less than 1.2 m / s, ensuring that the airflow has sufficient initial power to pass through the damping structure. On the other hand, the honeycomb damping structure has a large number of micropores and a total flow cross-sectional area much larger than the flow channel cross-sectional area on the air inlet side. When airflow enters the micropores, the flow channel space suddenly expands. According to fluid mechanics principles, the airflow velocity decreases as the flow cross-sectional area increases. Simultaneously, the walls of the honeycomb micropores generate frictional and local resistance to the airflow, further consuming its kinetic energy. This causes the airflow velocity to continuously decrease as it passes through the damping structure, eventually dropping to below 0.3 m / s by the time it reaches the air outlet. Furthermore, the regular honeycomb structure ensures uniform airflow distribution during flow, avoiding abnormal local velocities and ensuring the overall airflow velocity at the air outlet remains stable within the set range. This provides a stable airflow for the efficient purification of subsequent air purification units while preventing high-speed airflow from disturbing the subsequent cavity environment.

[0100] The air purification equipment includes a control unit, a first differential pressure sensor is installed between the outer protective cavity and the optical path cavity 3, and a second differential pressure sensor is installed between the optical path cavity 3 and the detection cavity 4. The first and second differential pressure sensors are respectively connected to the control unit. The air purification equipment also includes an exhaust unit 5, which is connected to the outer protective cavity, the optical path cavity 3, and the detection cavity 4. The exhaust unit 5 is located at the bottom of the frame 1. The first pipe, the second pipe, and the exhaust unit 5 are each equipped with a proportional adjustment mechanism, which is connected to the control unit.

[0101] A control system is constructed by setting up a control unit, a differential pressure sensor, and a proportional adjustment mechanism. The first differential pressure sensor can monitor the pressure difference between the outer protective cavity and the optical path cavity 3 in real time, and the second differential pressure sensor can monitor the pressure difference between the optical path cavity 3 and the detection cavity 4 in real time. The control unit adjusts the proportional adjustment mechanism according to the monitoring data to achieve precise dynamic control of the differential pressure setpoint from 1 Pa to 15 Pa, ensuring the stability of the system pressure fluctuation range is no greater than ±3%.

[0102] By setting an exhaust section 5 at the bottom of the frame 1, and connecting the exhaust section 5 to the outer protective cavity, the optical path cavity 3 and the detection cavity 4 respectively, it is convenient to centrally discharge pollutants, optimize the airflow circulation path, improve the efficiency of pollutant discharge, and the overall system has a high degree of automation and precise control, ensuring long-term stability of cleanliness and adapting to the high requirements of environmental stability for nanoscale detection.

[0103] The control unit is the controller of the air purification equipment. A first differential pressure sensor is installed between the outer protective cavity and the optical path cavity 3, and a second differential pressure sensor is installed between the optical path cavity 3 and the detection cavity 4. Both the first and second differential pressure sensors are electrically connected to the control unit, transmitting the monitored differential pressure data to it. The air purification equipment also includes an exhaust unit 5, which is connected to the outer protective cavity, the optical path cavity 3, and the detection cavity 4. The exhaust unit 5 is installed at the bottom of the frame 1, and exhausts the airflow from the outer protective cavity, the optical path cavity 3, and the detection cavity 4. A proportional adjustment mechanism is installed on the first pipe, the second pipe, and the exhaust unit 5. This proportional adjustment mechanism can be an electrically controlled regulating valve, electrically connected to the control unit. The control unit can adjust the proportional adjustment mechanism based on the feedback signal from the differential pressure sensor to achieve precise control of airflow and air pressure.

[0104] The exhaust section 5 includes an exhaust collection box, and the exhaust port of the outer protective cavity, the first exhaust port 32, and the second exhaust port 42 are all connected to the exhaust collection box.

[0105] A second aspect of this application provides a wafer inspection system, including a wafer inspection device and an air purification device as described above for wafer inspection, wherein the wafer inspection device is connected to the air purification device.

[0106] The wafer inspection system provided in this application embodiment includes an air purification device as described in any of the above technical solutions, and therefore possesses all the beneficial effects of the above technical solutions.

[0107] The air purification equipment and wafer inspection system provided in this application embodiment solve the key requirements of the semiconductor industry for nanoscale precision measurement, significantly reduce the concentration of submicron particles in the inspection environment, and thus effectively avoid secondary pollution problems caused by particle deposition on the surface of precision devices.

[0108] It will be readily understood by those skilled in the art that the aforementioned advantageous methods can be freely combined and superimposed without conflict.

[0109] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application. The above are merely implementation methods of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this application, and these improvements and modifications should also be considered within the protection scope of this application.

Claims

1. An air cleaning apparatus applied to wafer inspection, characterized by, The air purification device for wafer detection comprises a rack (1) and a blowing part (2), an outer protection cavity, a light path cavity (3) and a detection cavity (4) are arranged in the rack (1), the light path cavity (3) and the detection cavity (4) are arranged in the outer protection cavity, the blowing part (2) is communicated with the outer protection cavity, the light path cavity (3) and the detection cavity (4) respectively, so as to introduce air flow into the outer protection cavity, the light path cavity (3) and the detection cavity (4) respectively, the air pressure in the detection cavity (4) is greater than the air pressure in the light path cavity (3), and the air pressure in the light path cavity (3) is greater than the air pressure in the outer protection cavity.

2. The air purification device according to claim 1, characterized in that, The blowing part (2) comprises an air purification unit, an air inlet end of the air purification unit is communicated with an air source, and air outlet ends of the air purification unit are communicated with the outer protection cavity, the light path cavity (3) and the detection cavity (4) respectively.

3. The air purification device according to claim 2, characterized in that, The air purification unit is arranged at the top of the rack (1), and the air purification unit is communicated with the outer protection cavity, so as to introduce air flow into the outer protection cavity in the vertical downward direction.

4. The air purification device according to claim 3, characterized in that, The air flow introduced into the outer protection cavity through the air purification unit flows uniformly downward at a rate of 0.4 m / s to 0.5 m / s, and the outer protection cavity maintains a positive pressure of 1.8 Pa to 2.2 Pa relative to the external space of the rack (1).

5. The air purification device according to claim 2, wherein, The blowing part (2) further comprises a blowing and collecting box (21), the blowing and collecting box (21) is communicated with the air purification unit, the blowing and collecting box (21) is communicated with the light path cavity (3) through a first pipeline, and the blowing and collecting box (21) is communicated with the detection cavity (4) through a second pipeline.

6. The air purification device according to claim 5, characterized in that, First air inlets (31) and first air outlets (32) are arranged on the cavity wall of the light path cavity (3), the first air inlets (31) and the first air outlets (32) are arranged on different cavity walls of the light path cavity (3) respectively, and the first air inlets (31) are communicated with the first pipeline.

7. The air purification device according to claim 6, characterized in that The first air inlets (31) and the first air outlets (32) are arranged opposite to each other in the horizontal direction, so as to form a horizontal one-way flow field.

8. The air purification device of claim 6, wherein, The first air outlets (32) are provided with a first air extraction mechanism for extracting air flow in the light path cavity (3).

9. The air purification device of claim 8, wherein, The air volume accuracy of the first air extraction mechanism is ±3%.

10. A wafer inspection system, characterized by, The air purification device for wafer detection comprises a rack (1) and a blowing part (2), an outer protection cavity, a light path cavity (3) and a detection cavity (4) are arranged in the rack (1), the light path cavity (3) and the detection cavity (4) are arranged in the outer protection cavity, the blowing part (2) is communicated with the outer protection cavity, the light path cavity (3) and the detection cavity (4) respectively, so as to introduce air flow into the outer protection cavity, the light path cavity (3) and the detection cavity (4) respectively, the air pressure in the detection cavity (4) is greater than the air pressure in the light path cavity (3), and the air pressure in the light path cavity (3) is greater than the air pressure in the outer protection cavity.

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