Wafer adaptive focus defect detection device

Abstract

The application discloses a wafer adaptive focusing defect detection device, and relates to the field of wafer surface defect detection, comprising: a detection light source for providing a detection illumination beam to a wafer surface to be detected; an optical imaging assembly; a focusing module arranged in an optical path formed by the detection light source and the optical imaging assembly, the focusing module comprising a liquid lens, the adjusting part being used for adjusting the liquid interface curvature to realize focal length adjustment; an adaptive curvature compensation assembly connected with the liquid lens, used for actively compensating liquid interface disturbance caused by gravity or acceleration inside the liquid lens during movement or attitude change of the device. By adopting the above scheme, the liquid lens and the adaptive curvature compensation assembly are integrated, and optical stability of active disturbance suppression in a dynamic scanning process is realized in cooperation, high-speed focusing, high focusing accuracy and high-speed focusing are realized, and therefore the sensitivity and detection efficiency of wafer defect detection are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of wafer surface defect detection technology, and more particularly to a wafer adaptive focusing defect detection device. Background Technology

[0002] In integrated circuit manufacturing, wafer surface defect detection is a critical quality control step to ensure device yield and reliability. As process nodes continue to evolve towards deeper submicron and nanometer scales, the size of wafer surface structures continues to decrease, significantly increasing process complexity. Defects such as particle contamination, scratches, pits, and residues have an increasingly prominent impact on device electrical performance and yield. Therefore, after several key wafer manufacturing processes, such as photolithography, etching, chemical mechanical polishing (CMP), and thin film deposition, highly sensitive and stable defect detection of the wafer surface is necessary to achieve process monitoring and optimization.

[0003] Current wafer defect detection technologies are primarily based on optical detection methods. These methods identify and locate defects by illuminating the wafer surface and collecting reflected, scattered, or diffracted light signals. In wafer optical defect detection based on imaging or scattering signals, the detection object distance, as a key parameter of the optical system, directly affects the imaging magnification, depth of focus, and spatial distribution characteristics of the defect signal. Under different object distances, the energy distribution, contrast, and signal-to-noise characteristics of wafer surface defects on the detector vary significantly. This is especially true for tiny defects approaching the optical resolution limit, where the feasibility of detection is highly dependent on a suitable object distance setting. Traditional mechanical focusing systems, such as those involving moving the entire objective lens or lens group, suffer from high inertia, slow response, and limited positioning accuracy, making it difficult to achieve nanometer-level real-time focusing during high-speed scanning, resulting in insufficient sensitivity for detecting tiny defects. Furthermore, to rapidly complete the scanning and inspection of large-area wafers, the focusing system must have a millisecond-level response speed. The high inertia and wear of moving parts in traditional mechanical focusing severely limit the movement and scanning speed of the inspection platform.

[0004] Therefore, there is an urgent need to provide an adaptive focusing solution that can simultaneously meet the requirements of high precision, high speed, and high dynamic stability. This has become a key obstacle restricting the development of advanced wafer defect detection technology towards higher sensitivity and higher efficiency. Summary of the Invention

[0005] The purpose of this invention is to provide a wafer adaptive focusing defect detection device to solve the technical problems of insufficient focusing accuracy, limited response speed, and poor dynamic stability in existing wafer surface defect detection systems during high-speed scanning.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] A wafer adaptive focusing defect detection device includes: A detection light source is used to provide a detection illumination beam to the surface of the wafer to be inspected. An optical imaging component is disposed on the outgoing light path of the wafer and is used to receive light signals reflected or scattered by the surface of the wafer and to perform imaging. A focusing module is disposed in the optical path formed by the detection light source and the optical imaging component. The focusing module includes a liquid lens, which includes a first liquid, a second liquid, and an adjustment component. The first liquid and the second liquid have different refractive indices and form a variable curvature liquid interface inside the liquid lens. The adjustment component is used to adjust the curvature of the liquid interface to achieve focal length adjustment. An adaptive curvature compensation component, connected to the liquid lens, is used to actively compensate for disturbances at the liquid interface inside the liquid lens caused by gravity or acceleration during the movement or attitude change of the device, so as to maintain the optical stability of the liquid lens.

[0008] Furthermore, the adaptive curvature compensation component includes: A flexible transparent diaphragm is disposed inside the liquid lens to isolate the first liquid and the second liquid inside the liquid lens, forming a liquid interface with variable curvature; A liquid compensation component is in fluid communication with a chamber containing the first liquid or the second liquid; The liquid compensation component compensates for the deformation of the flexible transparent diaphragm by adjusting the volume or pressure of the compensation liquid during the movement or posture change of the device.

[0009] Furthermore, the adjusting element is an electrowetting drive element, comprising: The first electrode is electrically connected to the first liquid; The second electrode is electrically connected to the second liquid. The first electrode and the second electrode are respectively disposed on both sides of the flexible transparent membrane, and the curvature of the liquid interface is adjusted by changing the voltage applied between the first electrode and the second electrode.

[0010] Furthermore, the focusing module also includes: The second lens is arranged sequentially with the liquid lens along the optical path; A linear displacement drive is connected between the liquid lens and the second lens to drive the liquid lens and the second lens to undergo relative linear displacement.

[0011] Furthermore, the linear displacement drive includes a miniature piezoelectric ceramic actuator, one end of which is fixedly connected to the liquid lens and the other end of which is fixedly connected to the second lens; the miniature piezoelectric ceramic actuator is used to drive the relative linear displacement between the liquid lens and the second lens.

[0012] Furthermore, it also includes: A focusing drive mechanism is connected to the focusing module and is used to drive the focusing module to move in a direction perpendicular to the wafer surface in order to coarsely adjust the focusing distance of the optical imaging component.

[0013] Furthermore, it also includes: A height detection unit is used to acquire, in real time, the height information of the focusing module or the optical imaging component relative to a reference position; The aiming control unit is used to predict the surface height of multiple stations on the detection path of the wafer based on the known topography information of the wafer, and calculate the target height signal of the focusing drive mechanism at the corresponding station based on the predicted surface height.

[0014] Furthermore, it also includes: The instruction planning unit is communicatively connected to the pre-aiming control unit and is used to receive the target height signal; The instruction planning unit is used to combine the target height signal with the real-time height of the focusing module to generate a sequence of displacement control instructions to control the focusing drive mechanism to operate sequentially during the detection process.

[0015] Furthermore, the focusing drive mechanism receives and responds to the displacement control command sequence, and performs the corresponding displacement action.

[0016] Furthermore, it also includes: The closed-loop correction unit is communicatively connected to the height detection unit and the instruction planning unit, respectively, and is used to compare the actual displacement fed back by the height detection unit with the expected displacement corresponding to the displacement control instruction to obtain the displacement deviation. The control parameters of the instruction planning unit or subsequent displacement control instructions are dynamically corrected based on the displacement deviation.

[0017] Furthermore, the known morphological information of the wafer includes at least one of the following: product design thickness, wafer warpage distribution map, and actual height data recorded when inspecting the previous wafer in the same batch.

[0018] Furthermore, it includes an imaging and signal separation optical path, the optical path including a multi-wavelength illumination unit, an illumination mode switching unit, an illumination beam splitter and an imaging beam splitter arranged sequentially along the illumination optical path; The illumination beam splitter is used to deflect the illumination beam toward the surface of the wafer to be inspected, forming a coaxial illumination optical path; the imaging beam splitter is used to separate the reflected or scattered light signal returning from the wafer surface into at least two paths, one of which is transmitted to the imaging sensor for defect imaging, and the other is transmitted to the focusing sensing unit for real-time focusing or ranging.

[0019] Furthermore, the multi-wavelength illumination unit includes: Multiple light sources with different center wavelengths; A drive control circuit is used to drive at least one of the plurality of light sources to emit light in a time-sequential switching manner, so as to achieve time-division, single-wavelength illumination detection.

[0020] Furthermore, the lighting mode switching unit is a rotatable filter wheel, which is provided with a transparent window for providing bright field lighting, an annular light shield for providing annular dark field lighting, and a polarizer for providing polarized lighting.

[0021] The beneficial effects of the wafer adaptive focusing defect detection device provided by this invention are as follows: By introducing a liquid lens as a focusing module into the detection optical path and combining it with an adaptive curvature compensation component to dynamically stabilize the liquid interface morphology, a rapid focal length adjustment mechanism without large-inertia mechanical moving parts is achieved, thereby significantly reducing the system's motion inertia and mechanical wear risks. Based on this, the variable curvature interface formed by the first and second liquids can achieve continuous and controllable focal length changes under electrical signal drive, shortening the focusing response time to milliseconds or even lower, effectively meeting the real-time focusing requirements during high-speed wafer scanning. Simultaneously, the high precision of the liquid interface curvature adjustment enables nanometer-level equivalent object distance adjustment resolution, significantly improving the imaging clarity and signal-to-noise ratio of minute defects and enhancing the detection capability of defects approaching the optical resolution limit. Furthermore, by setting an adaptive curvature compensation component, the deformation of the liquid interface caused by changes in gravity components and acceleration disturbances during device movement, vibration, or attitude changes is actively corrected, significantly improving the focal length stability of the optical system under dynamic scanning conditions. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall structure of a wafer adaptive focusing defect detection device according to the present invention; Figure 2 This is a schematic diagram of the structure of the liquid lens according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of the liquid lens and the second lens according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the structure of the liquid compensation component according to an embodiment of the present invention; Figure 5This is a control flowchart of the wafer adaptive focusing defect detection device according to an embodiment of the present invention.

[0023] Reference numerals: 1. Detection light source; 11. Filter wheel; 2. Optical imaging assembly; 3. Liquid lens; 31. First liquid; 32. Second liquid; 33. First electrode; 34. Second electrode; 35. Insulating sheet; 36. Sealing shell; 37. Second lens; 4. Adaptive curvature compensation assembly; 41. Flexible transparent diaphragm; 42. Liquid compensation component; 5. Linear displacement drive component; 6. Height detection unit; 61. Focusing drive mechanism; 62. Command planning unit; 7. Pre-aiming control unit; 8. Closed-loop correction unit; 9. Known wafer topography information. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art. The terms "comprising" and similar expressions used herein mean that the element or object preceding the word covers the element or object listed after the word and its equivalents, but does not exclude other elements or objects.

[0025] Combined with appendix Figure 1 -Appendix Figure 5 The specific embodiments of the present invention will be further described in detail below.

[0026] Reference Figures 1-3 In some embodiments of the present invention, a wafer adaptive focusing defect detection device is provided. The device includes a detection light source 1, an optical imaging component 2, and a focusing module disposed in the optical path formed by the detection light source 1 and the optical imaging component 2, and works in conjunction with an adaptive curvature compensation component 4 to achieve stable focusing of the wafer under inspection during high-speed scanning. The detection light source 1 provides a detection illumination beam to the surface of the wafer under inspection. The optical imaging component 2 is disposed on the outgoing light path of the wafer and receives the light signal reflected or scattered by the wafer surface and performs imaging to acquire defect image data. The focusing module adjusts the focusing distance by changing the equivalent focal length of the optical path. The adaptive curvature compensation component 4 maintains the optical stability of the focusing module during device movement or attitude changes. Through the synergistic design of the above-described structure, the device achieves high-precision, high-response dynamic focusing control without relying on large-stroke mechanical movement.

[0027] In some embodiments of the present invention, the focusing module includes a liquid lens 3. The liquid lens 3 contains a first liquid 31 and a second liquid 32, which have different refractive indices and form a variable curvature liquid interface within the liquid lens 3. The liquid lens 3 has a sealing shell 36. The adjusting member is used to adjust the curvature of the liquid interface to change the equivalent focal length of the liquid lens 3. Preferably, the first liquid 31 is a conductive liquid, and the second liquid 32 is an insulating liquid, forming a stable interface structure within the sealed cavity. When the adjusting member is activated, the liquid interface deforms under the combined action of interfacial tension and an external driving field, thereby achieving continuous adjustment of the focal length. Compared to the traditional method of focusing by moving the entire objective lens or lens group, this structure significantly reduces the moment of inertia, shortens the response time, and avoids vibration and wear problems caused by large moving parts, which is beneficial for maintaining stable imaging quality during high-speed wafer scanning.

[0028] In some specific embodiments of the present invention, the adjusting member is an electrowetting drive member. The electrowetting drive member includes a first electrode 33 and a second electrode 34, the first electrode 33 and the second electrode 34 are provided with insulating sheets 35, and are electrically connected to a first liquid 31 and a second liquid 32, respectively. The first liquid 31 is preferably a conductive liquid containing an electrolyte, and the second liquid 32 is an insulating liquid that is immiscible with it. The first electrode 33 and the second electrode 34 are respectively disposed on both sides of the flexible transparent diaphragm 41 or on the cavity wall surface in contact with the liquid. By applying a controllable voltage between the first electrode 33 and the second electrode 34, an electric field distribution is formed at the interface between the first liquid 31 and the second liquid 32, thereby changing the equivalent interface energy at the interface. Its curvature adjustment mechanism is based on the electrowetting effect: when the applied voltage is zero, the interfacial tension between the first liquid 31 and the second liquid 32, and its contact angle with the solid interface, are in a natural equilibrium state, corresponding to a certain interfacial curvature. When a voltage is applied between the electrodes, the first liquid 31 containing the electrolyte undergoes charge redistribution under the action of the electric field, forming an electric bilayer structure at the liquid-solid interface, which leads to a decrease in interfacial free energy and a change in the contact angle. According to the functional relationship between the change in contact angle and the interfacial tension, the radius of curvature of the liquid interface changes accordingly, thereby causing a change in the equivalent focal length of the liquid lens 3. By adjusting the amplitude, polarity, and waveform of the applied voltage, continuous and reversible control of the interfacial curvature can be achieved.

[0029] Furthermore, the first liquid 31 containing the electrolyte can be an aqueous electrolyte solution or an ionic liquid system. By optimizing the electrolyte concentration and conductivity, the risk of electrolytic reaction can be reduced while ensuring driving sensitivity, thus improving interface stability. To prevent electrochemical side reactions or interface aging during long-term driving, an insulating dielectric layer or hydrophobic coating can be provided on the electrode surface, so that the electrowetting process is achieved through electric field coupling rather than direct current conduction, thereby improving service life. Through the above-mentioned electrowetting driving structure, the curvature adjustment of the liquid interface does not depend on mechanical movement, but achieves microscale deformation through interface energy regulation, which has the advantages of short response time, low inertia, low power consumption, and high-resolution adjustment. Its focus adjustment speed can reach millisecond level or even faster, and the adjustment process is continuous and smooth without mechanical shock, which is beneficial for maintaining a stable focus state during high-speed wafer scanning and platform acceleration and deceleration, significantly improving the imaging clarity and detection signal-to-noise ratio of small defects.

[0030] Reference Figure 4 In some embodiments of the present invention, the adaptive curvature compensation component 4 includes a flexible transparent diaphragm 41 and a liquid compensation element 42. The flexible transparent diaphragm 41 is disposed inside the liquid lens 3 to isolate the first liquid 31 from the second liquid 32, forming a liquid interface with variable curvature. The liquid compensation element 42 is in fluid communication with the chamber containing the first liquid 31 or the second liquid 32. During device movement or attitude changes, the liquid interface may undergo undesirable deformation due to changes in the direction of gravity or acceleration disturbances, affecting optical stability. By adjusting the volume or pressure of the compensation liquid through the liquid compensation element 42, the flexible transparent diaphragm 41 undergoes reverse compensation deformation, thereby offsetting the interface shift caused by external disturbances and achieving active stabilization control of the interface curvature. By adopting the above solution, the focal length stability of the system during high-speed scanning or platform acceleration and deceleration is effectively improved, the imaging drift caused by attitude changes is reduced, and the risk of false detection and missed detection is reduced.

[0031] In some specific embodiments of the present invention, the liquid compensation component 42 is an external liquid pump. The external liquid pump is connected to the chamber of the liquid lens 3 through a microfluidic pipeline, and can be selectively connected to the chamber containing the first liquid 31 or the chamber containing the second liquid 32. The external liquid pump is preferably a high-precision micro-metering pump or a piezoelectric micro-pump, and its output flow rate and pressure can be precisely adjusted under the drive of the control unit. When a change in device posture or acceleration / deceleration motion is detected that causes a shift in the liquid interface, the external liquid pump injects or extracts a small amount of liquid into the corresponding chamber, causing a compensatory change in the pressure inside the chamber, which in turn drives the flexible transparent diaphragm 41 to produce a reverse deformation to maintain the target curvature state of the liquid interface. To improve the compensation accuracy and response speed, the external liquid pump can be combined with a pressure sensor or displacement monitoring unit to form a closed-loop control structure, and dynamically correct the pumping flow rate by collecting chamber pressure or interface position change data in real time. With the above structure, the liquid compensation component 42 can not only achieve curvature locking control, but also stably maintain the liquid interface in a plane with curvature during the coarse adjustment stage, or provide a reference pressure environment for electrowetting drive during the fine adjustment stage, thereby improving the stability and repeatability of the overall focusing system.

[0032] In some embodiments of the present invention, the focusing module further includes a second lens 37 and a linear displacement drive 5. The second lens 37 and the liquid lens 3 are arranged sequentially along the optical path, and the linear displacement drive 5 is connected between the liquid lens 3 and the second lens 37 to drive them to undergo relative linear displacement. Through the synergistic effect of the curvature adjustment of the liquid lens 3 and the micro-displacement of the second lens 37, a wider range of focal length coverage and finer optical compensation can be achieved.

[0033] In some specific embodiments of the present invention, the liquid lens 3 and the second lens 37 in the focusing module cooperate to form a graded focusing structure, wherein the second lens 37 can be a fixed focal length lens or an optical lens that can participate in auxiliary adjustment. To achieve effective separation of coarse and fine adjustment, when performing large-range focal length adjustment, one of the lenses is preferentially driven to move relative to the optical axis by the linear displacement drive 5 to change the optical distance between the two lenses, thereby achieving coarse adjustment of the equivalent focal length. During the coarse adjustment process, in order to avoid the interface curvature change of the other liquid lens 3 from causing coupling interference to the overall focal length, the adaptive curvature compensation component 4 performs curvature locking control on the liquid lens 3. Specifically, the pressure of the chamber containing the first liquid 31 or the second liquid 32 is actively adjusted by the liquid compensation component 42, so that the flexible transparent diaphragm 41 is in a state of force balance, and the liquid interface is approximately planar, that is, the radius of curvature tends to be infinite, corresponding to an equivalent optical curvature of 0. At this time, the liquid lens 3 is equivalent to a parallel plate structure in the optical system, does not participate in focal length change, and exists only as a light-transmitting element. This method allows the focusing freedom to be concentrated on the axial displacement of a single lens during the coarse adjustment stage, avoiding the complexity of control caused by multiple variables and the resulting focal length drift.

[0034] After coarse adjustment and bringing the focal length close to the target focus position, the linear displacement drive 5 stops operating and remains in its current position. Then, the locking control on the curvature of the liquid lens 3 is released, and fine curvature adjustment of the liquid interface is performed via the electrowetting drive. By applying a precisely controlled driving voltage between the first electrode 33 and the second electrode 34, the contact angle between the electrolyte-containing first liquid 31 and the second liquid 32 is changed, transforming the liquid interface from a planar state to a spherical shape with minute curvature, thereby achieving small-range, high-resolution focal length fine-tuning. Because electrowetting adjustment has a fast response speed, high resolution, and does not involve large-scale mechanical movement, it is suitable for fine correction at the focus end. During the fine-tuning stage, the curvature adjustment amount typically varies within a small range, enabling nanometer-level equivalent object distance compensation and effectively eliminating focus deviation caused by local wafer warping or platform micro-vibrations.

[0035] In some other embodiments of the present invention, the roles of coarse adjustment and fine adjustment can also be interchanged. That is, the liquid lens 3 performs large-range curvature adjustment to achieve coarse adjustment, while the second lens 37 performs micro-displacement through a micro-piezoelectric ceramic actuator to achieve fine adjustment; or, during the coarse adjustment stage, one of the two liquid lenses 3 is locked in a curvature state, and only the other liquid lens 3 performs curvature adjustment. All of the above different combinations achieve decoupling of the focusing variables by locking the curvature compensation of the non-main focusing element at a certain stage, and all are optional implementations of the present invention.

[0036] The linear displacement drive 5 is preferably a miniature piezoelectric ceramic actuator, with one end fixedly connected to the liquid lens 3 and the other end fixedly connected to the second lens 37. Driven by an electrical signal, the miniature piezoelectric ceramic actuator generates micron-level or even sub-micron-level displacement changes for fine compensation of the optical path. This structure, while ensuring response speed, further improves the focusing range and accuracy, realizing a graded focusing strategy combining coarse and fine adjustments.

[0037] Reference Figure 5 In some specific embodiments of the present invention, the device further includes a focusing drive mechanism 61, used to drive the focusing module to move along a direction perpendicular to the wafer surface, so as to achieve coarse adjustment of the focusing distance of the optical imaging component 2. The focusing drive mechanism 61 can be a linear motor, a voice coil motor, or a high-precision ball screw slide structure. The focusing drive mechanism 61 completes the coverage of a large-stroke focusing range, while the liquid lens 3 and the micro piezoelectric ceramic actuator complete high-speed fine adjustment, thereby ensuring the focusing range while achieving high dynamic response capability.

[0038] In some embodiments of the present invention, a height detection unit 6 and a pre-aiming control unit 7 are also provided. The height detection unit 6 is used to acquire the height information of the focusing module or optical imaging component 2 relative to the reference position in real time, and can be implemented using a laser displacement sensor, a capacitive displacement sensor, or an optical interferometric ranging structure. The pre-aiming control unit 7 predicts the surface height of multiple stations on the detection path based on the known wafer topography information 9, and calculates the target height signal of the focusing drive mechanism 61 at the corresponding station based on the predicted surface height. The known wafer topography information may include the product design thickness, wafer warpage distribution map, or actual height data recorded during the inspection of the previous wafer in the same batch. Through the pre-aiming prediction mechanism, focus compensation commands can be generated in advance, reducing the amplitude of real-time closed-loop adjustment and improving overall scanning efficiency.

[0039] In some embodiments of the present invention, the instruction planning unit 62 is communicatively connected to the pre-aiming control unit 7, and is used to receive the target height signal and generate a sequence of displacement control instructions in combination with the real-time height of the focusing module, so as to control the focusing drive mechanism 61 to act sequentially during the detection process. The focusing drive mechanism 61 receives and responds to the displacement control instruction sequence and executes the corresponding displacement action. At the same time, a closed-loop correction unit 8 is provided, which is communicatively connected to the height detection unit 6 and the instruction planning unit 62, and is used to compare the actual displacement with the expected displacement to obtain the displacement deviation, and dynamically correct the control parameters or subsequent displacement control instructions according to the displacement deviation. Through the composite control strategy combining pre-aiming control and closed-loop correction, nanometer-level focusing accuracy can be maintained under high-speed motion, improving the dynamic stability and repeatability of the system.

[0040] In some specific embodiments of the present invention, an imaging and signal separation optical path is further included. This optical path includes a multi-wavelength illumination unit, an illumination mode switching unit, and an illumination beam splitter arranged sequentially along the illumination optical path, and an imaging beam splitter arranged along the return optical path. The illumination beam splitter refracts the illumination beam onto the surface of the wafer to be inspected, forming a coaxial illumination optical path; the imaging beam splitter separates the light signal returning from the wafer surface into at least two paths, one of which is transmitted to an imaging sensor for defect imaging, and the other is transmitted to a focusing sensor unit for real-time focusing or ranging. By separating and coordinating defect imaging and focusing / ranging functions at the optical path level, mutual interference can be avoided, and signal utilization efficiency can be improved.

[0041] In some embodiments of the present invention, the multi-wavelength illumination unit includes multiple light sources with different center wavelengths and a driving control circuit. The driving control circuit drives at least one of the multiple light sources to emit light in a time-sequential switching manner, realizing time-division, single-wavelength illumination detection. Different wavelengths can provide enhanced contrast for different types of defects, improving defect identification capabilities. The illumination mode switching unit is preferably a rotatable filter wheel 11, on which a transparent window, an annular light-blocking plate, and a polarizer are provided, respectively for providing bright-field illumination, annular dark-field illumination, and polarized illumination modes. By switching the illumination mode, optimized detection of different defect types such as particle defects, scratch defects, or film thickness variations can be performed, improving system adaptability.

[0042] In some other embodiments of the present invention, the driving method of the liquid lens 3 is not limited to an electrowetting drive, but can also employ a piezoelectric drive, electrostatic drive, or electromagnetic drive structure; the material of the flexible transparent diaphragm 41 can be a high-transmittance elastic polymer or a thin-film glass material; the liquid compensation component 42 can use a micro-injection pump or a flexible liquid storage chamber structure to achieve pressure regulation; the focusing drive mechanism 61 can also be modularly replaced according to the equipment platform structure. The imaging and signal separation optical path can also be adjusted to an inclined illumination or multi-angle scattering detection structure according to detection requirements. All the above alternative solutions are within the protection scope of the present invention, and as long as they do not depart from the technical concept and structural framework defined by the present invention, they should be covered within the protection scope of the present invention.

[0043] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0044] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0045] While embodiments of the present invention have been described in detail above, it will be apparent to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations fall within the scope and spirit of the present invention. Furthermore, the present invention described herein may have other embodiments and can be implemented or carried out in various ways.

Claims

1. A wafer adaptive focusing defect detection device, characterized in that, include: A detection light source is used to provide a detection illumination beam to the surface of the wafer to be inspected. An optical imaging component is disposed on the outgoing light path of the wafer and is used to receive light signals reflected or scattered by the surface of the wafer and to perform imaging. A focusing module is disposed in the optical path formed by the detection light source and the optical imaging component. The focusing module includes a liquid lens, which includes a first liquid, a second liquid, and an adjustment component. The first liquid and the second liquid have different refractive indices and form a variable curvature liquid interface inside the liquid lens. The adjustment component is used to adjust the curvature of the liquid interface to achieve focal length adjustment. An adaptive curvature compensation component, connected to the liquid lens, is used to actively compensate for liquid interface disturbances caused by gravity or acceleration inside the liquid lens during the movement or attitude change of the device, so as to maintain the optical stability of the liquid lens. The adaptive curvature compensation component includes: A flexible transparent diaphragm is disposed inside the liquid lens to isolate the first liquid and the second liquid inside the liquid lens, forming a liquid interface with variable curvature; A liquid compensation component is in fluid communication with a chamber containing the first liquid or the second liquid; The liquid compensation component compensates for the deformation of the flexible transparent diaphragm by adjusting the volume or pressure of the compensation liquid during the movement or posture change of the device. The focusing module also includes: The second lens is arranged sequentially with the liquid lens along the optical path; A linear displacement drive is connected between the liquid lens and the second lens, and is used to drive the liquid lens and the second lens to undergo relative linear displacement; Furthermore, during the coarse adjustment process of driving the liquid lens and the second lens to undergo relative linear displacement through the linear displacement drive, the pressure of the chamber containing the first liquid or the second liquid is actively adjusted by the liquid compensation component, so that the flexible transparent diaphragm is in a state of force balance, and the liquid interface has an approximately planar shape, that is, the corresponding equivalent optical curvature is 0.

2. The wafer adaptive focusing defect detection device according to claim 1, characterized in that, The adjusting component is an electrowetting drive component, comprising: The first electrode is electrically connected to the first liquid; The second electrode is electrically connected to the second liquid. The first electrode and the second electrode are respectively disposed on both sides of the flexible transparent membrane, and the curvature of the liquid interface is adjusted by changing the voltage applied between the first electrode and the second electrode.

3. The wafer adaptive focusing defect detection device according to claim 1, characterized in that, The linear displacement actuator includes a miniature piezoelectric ceramic actuator, one end of which is fixedly connected to the liquid lens and the other end of which is fixedly connected to the second lens; the miniature piezoelectric ceramic actuator is used to drive the relative linear displacement between the liquid lens and the second lens.

4. The wafer adaptive focusing defect detection device according to claim 1, characterized in that, Also includes: A focusing drive mechanism is connected to the focusing module and is used to drive the focusing module to move in a direction perpendicular to the wafer surface in order to coarsely adjust the focusing distance of the optical imaging component.

5. The wafer adaptive focusing defect detection device according to claim 4, characterized in that, Also includes: A height detection unit is used to acquire, in real time, the height information of the focusing module or the optical imaging component relative to a reference position; The aiming control unit is used to predict the surface height of multiple stations on the detection path of the wafer based on the known topography information of the wafer, and calculate the target height signal of the focusing drive mechanism at the corresponding station based on the predicted surface height.

6. The wafer adaptive focusing defect detection device according to claim 5, characterized in that, Also includes: The instruction planning unit is communicatively connected to the pre-aiming control unit and is used to receive the target height signal; The instruction planning unit is used to combine the target height signal with the real-time height of the focusing module to generate a sequence of displacement control instructions to control the focusing drive mechanism to operate sequentially during the detection process.

7. The wafer adaptive focusing defect detection device according to claim 6, characterized in that, The focusing drive mechanism receives and responds to the displacement control command sequence, and performs the corresponding displacement action.

8. A wafer adaptive focusing defect detection device according to claim 6 or 7, characterized in that, Also includes: The closed-loop correction unit is communicatively connected to the height detection unit and the instruction planning unit, respectively, and is used to compare the actual displacement fed back by the height detection unit with the expected displacement corresponding to the displacement control instruction to obtain the displacement deviation. The control parameters of the instruction planning unit or subsequent displacement control instructions are dynamically corrected based on the displacement deviation.

9. The wafer adaptive focusing defect detection device according to claim 5, characterized in that, The known morphological information of the wafer includes at least one of the following: product design thickness, wafer warpage distribution map, and actual height data recorded when inspecting the previous wafer in the same batch.

10. The wafer adaptive focusing defect detection device according to claim 1, characterized in that, It includes an imaging and signal separation optical path, which includes a multi-wavelength illumination unit, an illumination mode switching unit, an illumination beam splitter, and an imaging beam splitter arranged sequentially along the illumination optical path; The illumination beam splitter is used to deflect the illumination beam toward the surface of the wafer to be inspected, forming a coaxial illumination optical path; the imaging beam splitter is used to separate the reflected or scattered light signal returning from the wafer surface into at least two paths, one of which is transmitted to the imaging sensor for defect imaging, and the other is transmitted to the focusing sensing unit for real-time focusing or ranging.

11. The wafer adaptive focusing defect detection device according to claim 10, characterized in that, The multi-wavelength illumination unit includes: Multiple light sources with different center wavelengths; A drive control circuit is used to drive at least one of the plurality of light sources to emit light in a time-sequential switching manner, so as to achieve time-division, single-wavelength illumination detection.

12. The wafer adaptive focusing defect detection device according to claim 11, characterized in that, The lighting mode switching unit is a rotatable filter wheel, which is provided with a transparent window for providing bright field lighting, an annular light shield for providing annular dark field lighting, and a polarizer for providing polarized lighting.

Images