Reference modulator, complementary modulator, focusing device, method and semiconductor apparatus

Abstract

This application discloses a reference modulator, a complementary modulator, a focusing device, a method, and a semiconductor device, relating to the field of semiconductor technology. The first modulation section of the reference modulator modulates the illumination light, and two through-holes on its sides form two reference beams. When the object under test moves in both directions, the corresponding reference beams pre-illuminate the detection area before focusing, thereby obtaining the surface reflectivity. During bidirectional scanning of the object under test, changes in the surface reflectivity of the object under test can be sensed in real time before formal focusing. The operating parameters of the light source are dynamically adjusted based on these changes, enabling the focusing detector in the optical focusing device to avoid saturation distortion when detecting high-reflectivity areas and improve the signal-to-noise ratio when detecting low-reflectivity areas, always operating within the linear response range. This effectively solves the problem of insufficient detection accuracy caused by drastic changes in wafer surface reflectivity, significantly improving the overall focusing accuracy of the optical focusing device.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and in particular to a reference modulator, a complementary modulator, a focusing device, a method, and a semiconductor apparatus. Background Technology

[0002] In the field of semiconductor wafer inspection, the wafer surface contains various materials such as silicon substrate, silicon oxide, silicon nitride, polysilicon and metal interconnects, which have significant differences in reflectivity. This causes the detector to be prone to saturation distortion in high reflectivity areas when using the eccentric mask method for focusing, while the signal-to-noise ratio drops sharply in low reflectivity areas due to weak signals. Furthermore, the detector has difficulty adapting to the dynamic range in real time under scenarios of sudden changes in reflectivity, which seriously degrades the focusing accuracy.

[0003] Existing technologies attempt to suppress interference by introducing an independent monitoring optical path into the detection optical path to dynamically normalize the defocus signal. However, this approach requires high gain amplification in low-reflection areas, which introduces noise, and requires reduced gain in high-reflection areas, resulting in sensitivity loss. It is prone to insufficient detection accuracy due to drastic changes in wafer surface reflectivity, leading to technical problems such as low focusing accuracy. Summary of the Invention

[0004] This application discloses a reference modulator, a complementary modulator, a focusing device, a method, and a semiconductor device to solve the technical problem of insufficient detection accuracy caused by drastic changes in the reflectivity of the wafer surface, resulting in low focusing accuracy.

[0005] In a first aspect, this application provides a reference modulator applied to an optical focusing device. The optical focusing device includes a light source and a detection component. The light source is used to generate illumination light, and the optical focusing device is used to focus on an object under test. The object under test is capable of moving along a first direction and a second direction opposite to the first direction. The reference modulator includes: A first substrate, wherein the first substrate has a first through hole and a second through hole; A first modulation section is disposed on a first substrate, and a first through hole and a second through hole are located on both sides of the first modulation section; The first modulation unit is used to modulate the illumination light to form a first modulation beam, which is then used to focus the object under test. The first through hole is used to allow illumination light to pass through in order to form a first reference beam. The first reference beam is used to illuminate the detection area in advance during the process of the object under test moving along the first direction, before focusing the detection area of ​​the object under test using the first modulated beam, so as to obtain the first surface reflectivity of the detection area through the detection component, and then dynamically adjust the working parameters of the light source according to the first surface reflectivity. The second through-hole is used to allow illumination light to pass through, so as to form a second reference beam. The second reference beam is used to illuminate the detection area in advance during the movement of the test object along the second direction, before focusing the detection area of ​​the test object using the first modulated beam, so as to obtain the second surface reflectivity of the detection area through the detection component, and then dynamically adjust the working parameters of the light source according to the second surface reflectivity.

[0006] The reference modulator provided in this application comprises a first modulation section for modulating illumination light, and a first through-hole and a second through-hole located on both sides of the first modulation section, on a first substrate. The first through-hole allows illumination light to pass through to form a first reference beam, and the second through-hole allows illumination light to pass through to form a second reference beam. During the movement of the object under test along a first direction, the first reference beam can illuminate the detection area of ​​the object under test in advance before focusing using the first modulated beam, thereby obtaining the first surface reflectivity of the detection area through a detection component, and then dynamically adjusting the operating parameters of the light source based on the first surface reflectivity. Similarly, during the movement of the object under test along a second direction opposite to the first direction, the second reference beam can illuminate the object under test using the first modulated beam. Before focusing on the area to be detected, the area is illuminated in advance to obtain the second surface reflectance of the area through the detection component. Then, the operating parameters of the light source are dynamically adjusted according to the second surface reflectance. Therefore, the above scheme ensures that the surface reflectance change of the test object can be sensed in real time before the formal focusing during the bidirectional scanning process. The operating parameters of the light source (such as current, voltage, output power, etc.) are dynamically adjusted according to the surface reflectance change. This allows the focusing detector in the optical focusing device to avoid saturation distortion when detecting high reflectance areas and improve the signal-to-noise ratio when detecting low reflectance areas, always operating in the linear response range. This effectively solves the problem of insufficient detection accuracy caused by drastic changes in wafer surface reflectance and significantly improves the overall focusing accuracy of the optical focusing device.

[0007] In one possible implementation, the first substrate has a third through hole, and the first modulation unit is fixedly installed in the third through hole. This allows the first modulation unit and the through hole structure on the first substrate to be integrated into the same substrate, effectively reducing the overall structural volume and improving the device integration and structural compactness. At the same time, it can ensure higher relative positional accuracy between the first modulation unit and each through hole, making the assembly more stable and reliable, and avoiding the relative positional shift between the main modulation beam and the reference beam due to installation deviation. This further ensures the stability of the optical path reference and improves the accuracy of system focusing and precision detection.

[0008] In one possible implementation, a transparent substrate is used as the first substrate, and the first modulation unit is fixedly mounted on its surface. This ensures that the illumination light can pass smoothly through the substrate to form a reference beam, while providing a flat and stable support for the first modulation unit. This improves the overall structural rigidity and installation positioning accuracy, prevents the first modulation unit from shifting or deforming during operation, and ensures that the relative position of the main modulation beam and the two reference beams is stable and reliable. This is beneficial for maintaining the reference stability during focusing and detection, and further improves the focusing accuracy and detection reliability of the system.

[0009] In one possible implementation, the first through hole and the second through hole are symmetrically arranged on both sides of the first modulation section. This ensures that the relative spatial position relationship between the first reference beam and the modulation beam, and the relative spatial position relationship between the second reference beams, remain consistent as the object under test moves along the first or second direction. This eliminates measurement errors or response delay differences caused by structural asymmetry, allowing the optical focusing device to dynamically adjust the detector parameters based on unified pre-acquired reflectivity data during bidirectional scanning, further ensuring the consistency of focusing accuracy.

[0010] Secondly, this application provides a complementary modulator, used in conjunction with the aforementioned reference modulator, comprising: The second substrate has a first blocking part and a second blocking part. The first blocking part is positioned corresponding to the first through hole and is used to block the first reference sub-beam generated after the first reference beam is incident on the test object from passing through. The second blocking part is positioned corresponding to the second through hole and is used to block the second reference sub-beam generated after the second reference beam is incident on the test object from passing through. The second modulation unit is disposed on the second substrate. The second modulation unit and the first modulation unit are offset from each other on the pupil surface or the conjugate surface. The second modulation unit is used to modulate the first modulation reflection beam generated after the first modulation beam is incident on the test object to form the second modulation reflection beam.

[0011] The complementary modulator provided in this application, by setting a first blocking part corresponding to the position of the first through hole and a second blocking part corresponding to the position of the second through hole, can accurately intercept the first reference sub-beam generated by the reflection of the first reference beam by the object under test and the second reference beam generated by the reflection of the second reference beam by the object under test. At the same time, the second modulation part is mounted on the second substrate and is staggered with the first modulation part on the pupil surface or conjugate surface, so that the second modulation part can perform secondary modulation on the first modulation reflected beam to generate the second modulation reflected beam. The above settings fundamentally eliminate the noise superposition and signal crosstalk caused by the mixing of the first reference sub-beam and the second reference sub-beam into the second modulation reflected beam, significantly improve the purity and signal-to-noise ratio of the detector received signal in the optical focusing device, and further ensure the focusing accuracy and stability of the optical focusing system in complex reflectivity environments.

[0012] In one possible implementation, the second substrate has a fourth through hole, and the second modulation unit is fixedly installed in the fourth through hole. This allows the second modulation unit and the blocking structure on the second substrate to be integrated into the same substrate. While improving the overall integration and structural compactness of the device, it also ensures higher relative positional accuracy between the second modulation unit and the blocking parts on both sides, making the assembly more stable and reliable. This effectively avoids problems such as optical path misalignment and signal crosstalk caused by installation gaps or positional offsets, thereby ensuring stable and accurate modulation of the main modulation reflected beam and further improving the reliability and accuracy of optical focusing and precision detection.

[0013] In one possible implementation, the second substrate is a transparent substrate, and the second modulation part, the first blocking part, and the second blocking part are all fixedly mounted on its surface. On the one hand, this can ensure normal transmission of the light beam and avoid the substrate itself from blocking or losing the effective optical path. On the other hand, it can provide a flat and uniform mounting base for the second modulation part and the two blocking parts, making the relative position accuracy between the functional structures higher, the overall structure more stable and reliable, effectively reducing the risk of optical path offset caused by assembly errors, and facilitating precise optical path coordination with the reference modulator. This can reliably achieve modulation of the main modulation reflected beam and blocking of the reference sub-beam, while ensuring the stability of the focusing reference, further improving the focusing accuracy and detection stability of the system.

[0014] Thirdly, this application also provides a detection component for use in conjunction with the aforementioned reference modulator, comprising: The mounting plate has a fifth through hole for the first modulated reflected beam generated after the first modulated beam is incident on the object under test to pass through. The first detection element is disposed on the mounting plate and its position corresponds to the first through hole. It is used to receive the first reference sub-beam generated after the first reference beam is incident on the object under test. The second detection element is disposed on the mounting plate and corresponds to the position of the second through hole. It is used to receive the second reference sub-beam generated after the second reference beam is incident on the object under test.

[0015] The detection component works in conjunction with the reference modulator. A fifth through hole is provided on the mounting plate to allow the first modulated reflected beam of the main optical path to pass through. At the same time, a first detection element and a second detection element are provided corresponding to the positions of the first through hole and the second through hole.

[0016] The detection assembly provided in this application includes a mounting plate, a first detection element, and a second detection element. A fifth through-hole in the mounting plate is specifically designed for the passage of a first modulated reflected beam, allowing it to enter the subsequent imaging or main detection optical path without being obstructed by the reference optical path elements. Simultaneously, the first and second detection elements are precisely positioned corresponding to the positions of the first and second through-holes, respectively, ensuring that when the object under test moves along the first or second direction, the first detection element can independently and in real-time acquire the first reference sub-beam formed by the reflection of the first reference beam, and the second detection element can independently and in real-time acquire the first reference sub-beam formed by the reflection of the first reference beam. The second reference sub-beam, formed by the reflection of the two reference beams, allows the system to acquire surface reflectivity data of the detected area in real time before focusing, regardless of the direction in which the object under test is scanned. This eliminates the blind spot of unidirectional detection and ensures the continuity and full coverage of focusing parameter adjustment. In addition, by physically isolating the first and second reference sub-beams from the first modulated reflected beam at the optical path receiving end, saturation interference or crosstalk of strong reference light to the main detection channel is effectively avoided, ensuring a high signal-to-noise ratio of the main detection signal, while also ensuring the independence and accuracy of the reference light signal.

[0017] Fourthly, this application also provides an optical focusing device, comprising: A light source, used to provide illumination; The reference modulator provided in the above embodiments is disposed in the transmission optical path of the illumination light and is used to form a first reference beam, a second reference beam, and a first modulated beam; A focusing module is set in the post-stage optical path of the reference modulator. It is used to project the first reference beam, the second reference beam and the first modulation beam onto the surface of the object under test, and to collect the first reference sub-beam, the second reference sub-beam and the first modulation reflection beam generated on the surface of the object under test. The first reference sub-beam corresponds to the first reference beam, the second reference sub-beam corresponds to the second reference beam, and the first modulation reflection beam corresponds to the first modulation beam. The beam splitting module is located in the post-focusing optical path of the focusing module and is used to split the first reference sub-beam, the second reference sub-beam and the first modulated reflection beam into the first detection optical path and the second detection optical path. The complementary modulator provided in the above embodiment is disposed in the first detection optical path and is used to modulate the first modulated reflection beam corresponding to each position point during the scanning process of the focusing module or the motion stage carrying the object to be tested along a preset direction, so as to form a second modulated reflection beam. The first detector is set in the optical path of the complementary modulator to detect the second modulated reflected beam and obtain multiple first photoelectric signals. The detection component provided in the above embodiments is disposed in the second detection optical path and is used to detect the first reference sub-beam or the second reference sub-beam to obtain a second photoelectric signal; The second detector is set in the second detection optical path and is used to detect the first modulated reflected beam corresponding to each position point during the scanning process of the focusing module or the moving stage carrying the object to be tested along the preset direction, so as to obtain multiple third photoelectric signals. The control processing unit is connected to the light source, the first detector, the detection assembly, the second detector, and the focusing module. The control processing unit is used for: Based on the second photoelectric signal, determine whether the output power of the light source meets the focusing requirements; If the output power of the light source does not meet the focusing requirements, control the light source to adjust its output power. After the output power of the light source meets the focusing requirements, the focusing module or the motion stage carrying the object to be tested is controlled to scan along a preset direction to obtain the first photoelectric signal and the third photoelectric signal corresponding to each position point of the focusing module or the motion stage carrying the object to be tested. The first defocusing amount of the object under test is determined based on the first photoelectric signal and the third photoelectric signal corresponding to each position point; Based on the first defocusing amount, control the focusing module or the motion stage carrying the test object to move so that the surface of the test object is located at the focal point of the first modulated beam.

[0018] This optical focusing device uses a reference modulator to simultaneously generate a first modulated beam, a first reference beam, and a second reference beam. A focusing module projects these beams onto the surface of the object under test and collects the corresponding reflected beams. The beams are then transmitted via a beam splitter, enabling independent transmission and collaborative operation of the main modulated optical path and the reference optical path. The complementary modulator and the first detector process the first modulated reflected beam formed by the reflection of the first modulated beam from the object under test, forming a second modulated reflected beam and obtaining a first photoelectric signal. The second detector directly acquires the first modulated reflected beam corresponding to each position point to obtain a third photoelectric signal. The detection component specifically receives the reflected sub-beams corresponding to the two reference beams and outputs a second photoelectric signal. While retaining the main optical path's focusing detection function, a stable and reliable reference standard is introduced simultaneously, fundamentally solving the technical problems of traditional optical modulators failing to provide an effective reference optical path, easily exhibiting focusing deviations, and insufficient detection accuracy. Furthermore, the control processing unit can determine whether the output power of the light source meets the focusing requirements based on the second photoelectric signal detected by the detection component. If the output power of the light source does not meet the focusing requirements, the control unit adjusts the output power of the light source. This avoids insufficient signal-to-noise ratio in low-reflectivity areas of the test object, which can lead to insufficient effective signals received by the second detector, and avoids saturation of the second detector in high-reflectivity areas. This ensures that the second detector in the optical focusing device can maintain effective detection capability across the entire reflectivity range of the test object, expanding the matching capability of the optical focusing device for test objects with different reflectivities. In addition, because the power of the light source is adjusted in advance based on the signal collected by the detection component, the output power of the light source meets the focusing requirements. The focusing requirement ensures that the second detector maintains effective detection capability, thus guaranteeing the effectiveness of the third photoelectric signal. Furthermore, once the output power of the light source meets the focusing requirement, the focusing module or the motion stage carrying the object under test is controlled to scan along a preset direction, acquiring the first and third photoelectric signals corresponding to each position point of the focusing module or the motion stage carrying the object under test. When determining the first defocus amount of the object under test based on the first and third photoelectric signals corresponding to each position point, the accuracy of the first defocus amount determination is improved. Finally, because the determined first defocus amount is relatively accurate, when controlling the movement of the focusing module or the motion stage carrying the object under test based on this first defocus amount, focusing can be completed more precisely, improving focusing accuracy.

[0019] In one possible implementation, the second detector is positioned in the subsequent optical path of the detection component. Based on the detection component's accurate reception and transmission of the first and second reference sub-beams to provide a stable reference signal, the second detector can specifically receive the first modulated reflected beam transmitted through the detection component's optical path. This avoids signal crosstalk between the first modulated reflected beam and the reference sub-beam during transmission, ensuring the second detector can accurately capture the third photoelectric signal corresponding to each position point. Furthermore, the second detector's placement in the subsequent optical path of the detection component allows the detection component to receive the first or second reference sub-beam earlier than the second detector receives the first modulated reflected beam. This allows for advance adjustment of the light source power based on the signal acquired by the detection component, ensuring the light source's output power meets focusing requirements. This avoids insufficient signal-to-noise ratio in low-reflectivity areas of the test object, preventing insufficient effective signal received by the second detector, and avoids saturation of the second detector in high-reflectivity areas. This ensures the second detector in the optical focusing device maintains effective detection capability across the entire reflectivity range of the test object, expanding the optical focusing device's compatibility with test objects of different reflectivities.

[0020] In one possible implementation, the first modulated beam needs to be clearly projected onto the surface of the object under test. Therefore, a conjugate relationship is required between the reference modulator and the surface of the object under test to ensure that the first modulated beam forms a clear periodic pattern on the surface of the object under test, providing an accurate optical signal for subsequent photoelectric signal acquisition and processing.

[0021] In one possible implementation, a complementary modulator is used to further modulate the reflected image of the reference modulator. The complementary modulator and the reference modulator need to be conjugate to ensure that the image of the reference modulator can be clearly formed on the complementary modulator to form a second modulated reflected beam, providing an accurate optical signal for subsequent photoelectric signal acquisition and processing.

[0022] In one possible implementation, the conjugate surface of the reference modulator and the photosensitive surface of the detector component need to be conjugate to ensure that the image of the reference modulator can be clearly formed on the first and second detector elements, providing accurate optical signals for subsequent photoelectric signal acquisition and processing.

[0023] In one possible implementation, the focusing module is a single structure of an objective lens or a focusing assembly, or a combination of a focusing assembly and an objective lens, and is set in the optical path between the reference modulator and the object under test. This allows for flexible adaptation to different focusing accuracies and optical path space requirements. A single structure can achieve a compact and simple optical path layout, reducing assembly complexity, while a combined structure can achieve more precise beam control and focus adjustment.

[0024] Fifthly, this application also provides a semiconductor device, including the aforementioned optical focusing device.

[0025] The semiconductor device provided in this application includes the aforementioned optical focusing device. It has the same or corresponding technical features as the optical focusing device mentioned above, and has the same effects.

[0026] Sixthly, this application also provides a focusing control method applied to the control processing unit in the aforementioned optical focusing device, comprising: Acquire the second photoelectric signal; Based on the second photoelectric signal, determine whether the output power of the light source meets the focusing requirements; If the output power of the light source does not meet the focusing requirements, control the light source to adjust its output power. After the output power of the light source meets the focusing requirements, the focusing module or the motion stage carrying the object to be tested is controlled to scan along a preset direction to obtain the first photoelectric signal and the third photoelectric signal corresponding to each position point of the focusing module or the motion stage carrying the object to be tested. The first defocusing amount of the object under test is determined based on the first photoelectric signal and the third photoelectric signal corresponding to each position point; Based on the first defocusing amount, control the focusing module or the motion stage carrying the test object to move so that the surface of the test object is located at the focal point of the first modulated beam.

[0027] The focusing control method provided in this application is applied to the control processing unit in the aforementioned optical focusing device, and has the same or corresponding technical features as the aforementioned optical focusing device, with the same effect.

[0028] In one possible implementation, before acquiring the second photoelectric signal, the transmission time of the signal used to characterize and adjust the output power of the light source is determined. This synchronizes the change in light source power with the scanning time of different reflectivity regions of the object under test, avoiding lag or lead in light intensity adjustment due to timing deviations. This ensures stable and appropriate light intensity signals are obtained in both high and low reflectivity regions of the object under test, further improving the adaptability and detection accuracy of the optical focusing device.

[0029] In one possible implementation, determining the transmission time of the target signal includes: acquiring the distance between the first modulation unit in the reference modulator and the target via, the projection magnification of the reference modulator, the scanning rate, and the communication delay between itself and the light source; wherein the target via is either the first via or the second via; and determining the transmission time of the target signal based on the distance between the first modulation unit and the target via, the projection magnification of the reference modulator, the scanning rate, and the communication delay between itself and the light source. Specifically, the transmission time difference is calculated based on the distance between the first modulation unit and the target via, the projection magnification, and the scanning rate, wherein the response time difference is the distance between the first modulation unit and the target via divided by the product of the projection magnification and the scanning rate; and the communication delay is subtracted from the response time difference to obtain the transmission time of the target signal. This application, when calibrating the target signal transmission time, comprehensively considers the structure of the reference modulator, projection magnification, scanning rate, and communication delay parameters. It can accurately calculate the response time difference required for adjusting the light source power, thereby precisely determining the timing of the target signal transmission. This ensures that the change in light source power is strictly matched with the scanning time of different reflectivity regions of the test object, avoiding signal saturation or insufficient signal-to-noise ratio caused by timing deviations. This significantly improves the adaptability, stability, and detection accuracy of the optical focusing device during high-speed scanning.

[0030] In one possible implementation, acquiring the second photoelectric signal includes: acquiring multiple second photoelectric signals collected by the detection component within a target time period when the illumination light is incident on the target through-hole; wherein the target time is the ratio of the diameter of the target through-hole to the scanning rate, and the target through-hole is either a first through-hole or a second through-hole; calculating the average of the multiple second photoelectric signals, and using the average of the multiple second photoelectric signals as the final second photoelectric signal. In this application, the target time is first determined based on the ratio of the diameter of the target through-hole to the scanning rate, and then the average of the multiple second photoelectric signals collected by the detection component within the target time period is used as the final second photoelectric signal, which improves the accuracy of the determined second photoelectric signal.

[0031] In one possible implementation, before controlling the light source to adjust its output power, the adjustment current value of the light source is first determined, so that the power of the light source can be adjusted based on the adjustment current value. In addition, when determining the adjustment current value of the light source, the corresponding first ideal voltage value is first determined according to the characteristics of the second detector, and the actual voltage value measured by the detection component is obtained. On the surface of the object to be tested with consistent reflectivity, the first measured voltage value measured by the second detector and the second measured voltage value measured by the detection component are obtained respectively. A proportionality coefficient is calculated, where the proportionality coefficient is the ratio of the first measured voltage value to the second measured voltage value. Finally, based on the first ideal voltage value, the actual voltage value, the proportionality coefficient, and the current value of the light source when the illumination light is incident on the target through-hole, the adjustment current value of the light source is accurately determined.

[0032] In one possible implementation, the object under test is initially focused before acquiring the second photoelectric signal. This initial focusing provides a foundation for subsequent high-precision focusing, improving focusing efficiency. Furthermore, a first image of the object's surface is acquired using a camera; the defocus amount is determined based on the first image; and the motion stage is controlled based on the defocus amount to perform initial focusing on the object. This eliminates the need for repeated manual adjustments to the focus position, enabling automated control of the focusing process, rapidly reducing defocus deviation, and improving focusing efficiency.

[0033] In one possible implementation, the focusing operation is started and stopped based on the positional relationship between the object under test, the objective lens field of view, and the through-hole projection. The focusing operation is only performed when the object under test is detected to be within the objective lens field of view, preventing invalid operations and resource waste. Simultaneously, during the scanning process, the object under test is controlled to move precisely to the corresponding projection position in a specified direction before the detection component is controlled to detect the target reference sub-beam, thereby acquiring the second photoelectric signal, which improves the effectiveness and reliability of signal acquisition. In addition, adjacent scanning lines adopt a reverse movement method, which makes the scanning action smoother and more continuous, further improving the overall focusing and detection efficiency, making the entire focusing process more efficient and stable.

[0034] In one possible implementation, after controlling the object under test to move along the projection position of the target through-hole on the plane of the object under test towards the projection position of the first modulation unit on the plane of the object under test, the method further includes: if it is detected that the object under test has moved outside the projection area of ​​the first modulation unit on the object under test, then the focus enable is stopped from being sent to stop the focus operation; and the detection component is controlled to clear the collected data. This ensures that the optical focusing device only works within the effective detection area and releases the space occupied by the collected data in the detection component, reducing invalid calculations and resource consumption, thereby improving the efficiency and stability of focus control.

[0035] In one possible implementation, after clearing the collected data using the detection component, the method further includes: starting to scan the next row of the target row; returning to the step of controlling the object under test (DUT) to move along the projection position of the target aperture on the plane of the DUT towards the projection position of the first modulation unit on the plane of the DUT during the target row scan; and, upon detecting that the DUT has moved to the projection position of the target aperture of the reference modulator on the plane of the DUT, controlling the detection element in the detection component corresponding to the target aperture to detect the target reference sub-beam. This allows for continuous focus detection row by row, reducing manual intervention. Simultaneously, clearing data before each row scan avoids data residue interference, resulting in more accurate detection results for each row and a more coherent overall scanning process.

[0036] In one possible implementation, since the power of the light source is adjusted in advance based on the signal collected by the detection component, the output power of the light source meets the focusing requirements, ensuring that the second detector maintains effective detection capability, that is, ensuring the effectiveness of the third photoelectric signal. Then, after the output power of the light source meets the focusing requirements, the focusing module or the motion stage carrying the object to be tested is controlled to scan along a preset direction to acquire the first photoelectric signal and the third photoelectric signal corresponding to each position point of the focusing module or the motion stage carrying the object to be tested. Based on the first photoelectric signal and the third photoelectric signal corresponding to each position point, the first departure point of the object to be tested is determined. When determining the focal length, the accuracy of determining the first defocus amount is improved. Since the determined first defocus amount is more accurate, when controlling the focusing module or the motion stage carrying the test object to move according to the first defocus amount, focusing can be completed more precisely, thus improving focusing accuracy. In addition, after the output power of the light source meets the focusing requirements, the focusing module or the motion stage carrying the test object is controlled to scan along the direction from the projection position of the target through hole on the plane of the test object to the projection position of the first modulation unit on the plane of the test object, and the focusing operation is started, avoiding invalid focusing operations when the first modulation unit is outside the projection area on the test object.

[0037] In one possible implementation, during the focusing process, a second photoelectric signal collected by the detection component is also received. Since the focusing module or the motion stage carrying the object scans along the direction from the projection position of the target through-hole on the plane of the object to the projection position of the first modulation unit on the plane of the object, the detection component acquires the second photoelectric signal obtained after passing through the target through-hole earlier than the third photoelectric signal received by the second detector after passing through the first modulation unit. That is, the power of the light source is adjusted in advance based on the photoelectric signal collected by the detection component at the previous position, so as to avoid saturation or insufficient signal-to-noise ratio of the second detector during the focusing process at the later position, ensuring that the second detector is in a stable state, improving the accuracy of reflectivity signal detection, thereby improving the accuracy of defocus signal determination, and thus improving focusing accuracy. Furthermore, after determining the target current value to be set for the light source based on the second photoelectric signal, it is judged whether the target current value is within the current threshold range. If the current exceeds the threshold range, it indicates that adjusting the current value of the power supply is insufficient to balance the energy received on the second detector. Therefore, in this application, when the current exceeds the threshold range, the focus enable is stopped, thereby avoiding the problem of low focus accuracy caused by the low accuracy of the third photoelectric signal collected by the second detector. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 A schematic diagram of a semiconductor device provided in an embodiment of this application; Figure 2 A structural diagram of an optical focusing device provided in an embodiment of this application; Figure 3 A schematic diagram of a reference modulator provided in an embodiment of this application; Figure 4 A schematic diagram of another reference modulator provided in an embodiment of this application; Figure 5 A schematic diagram illustrating the use of an optical focusing device in conjunction with an imaging system, as provided in this application embodiment; Figure 6 A schematic diagram of a complementary modulator provided in an embodiment of this application; Figure 7 A schematic diagram of another complementary modulator provided in an embodiment of this application; Figure 8 A schematic diagram of a detection component provided in an embodiment of this application; Figure 9 A flowchart of a focusing control method provided in an embodiment of this application; Figure 10 This application provides a schematic diagram of the motion trajectory of a motion table. Figure 11 A schematic diagram illustrating the correspondence between the projected positions of the object under test and the reference modulator when the motion table moves in a first direction, as provided in an embodiment of this application. Figure 12 A schematic diagram illustrating the correspondence between the projected positions of the object under test and the reference modulator when the motion table moves in the second direction, as provided in an embodiment of this application. Figure 13 This is a schematic diagram illustrating the averaging of data provided in an embodiment of this application; Figure 14 A schematic diagram showing the correspondence between the projection of the reference modulator onto the plane where the object to be measured is located and the object to be measured during a focusing process provided in an embodiment of this application; Figure 15 This application provides an embodiment of a detection component, a second detector, and a curve showing the change in the driving current or power of the light source before adjusting the power of the light source. Figure 16 This application provides an embodiment of a detection component, a second detector, and a curve showing the change in the driving current or power of the light source after adjusting the power of the light source. Figure 17 A flowchart of a focusing control method for automatically adapting to changes in wafer reflectivity, provided in an embodiment of this application.

[0040] Explanation of reference numerals in the attached figures: 1000 - Semiconductor Equipment; 100 - Optical focusing device; 200 - Collection system; 300 - Imaging system; 30001 - Imaging module; 30002 - Beam splitter element; 1-Light source; 2-Reference modulator; 21-First substrate; 211-First through hole; 212-Second through hole; 213-First modulation unit; 214-Third through hole; 2110-Projection of the first through hole; 2120-Projection of the second through hole; 2130-Projection of the first modulation unit; 3-Focusing module; 31-Objective lens; 32-Focusing assembly; 321-Focusing motor; 322-Focusing lens; 4-Spectral Module; 41-First beam splitter; 42-Second beam splitter; 5-Complementary modulator; 51-Second substrate; 511-First blocking portion; 512-Second blocking portion; 513-Second modulation portion; 514-Fourth through hole; 6-First detector; 7-Detection components; 71-Mounting plate; 711-Fifth through hole; 712-First detection element; 713-Second detection element; 8-Second detector; 9-Control processing unit; 10 - Item to be tested; 11-Motion control module; 12-Sports table; 13-Collimating element; 14-First focusing element; 15 - Second focusing element; 16-Control unit. Detailed Implementation

[0041] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of this application.

[0042] The core of this application is to provide a reference modulator, a complementary modulator, a focusing device, a method, and a semiconductor device to solve the technical problem of insufficient detection accuracy caused by drastic changes in the reflectivity of the wafer surface, resulting in low focusing accuracy.

[0043] To enable those skilled in the art to better understand the present application, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0044] In semiconductor equipment, optical focusing devices are often used in conjunction with other systems in various processes. For example, to ensure clear imaging of the object under test (DUT) in an imaging system and guarantee detection accuracy, an optical focusing device is typically configured. Semiconductor equipment integrating optical focusing devices and imaging systems is mainly used in semiconductor wafer inspection, photolithography alignment, and precision alignment scenarios. It can be applied to equipment such as optical inspection equipment, precision alignment systems, and wafer alignment platforms. It is usually connected to a light source, detector, drive mechanism, and processing unit, and ensures clear imaging and accurate positioning through imaging and autofocus, providing high-precision imaging for semiconductor processing and inspection.

[0045] In practice, the reflectivity of a wafer surface varies greatly due to the deposition of different materials in different areas (e.g., silicon substrate, silicon oxide region, silicon nitride region, polysilicon gate, metal interconnects, photoresist coverage area, etc.), ranging from 3% to over 90%. Most focusing techniques used in semiconductor detection are affected by these abrupt changes in reflectivity. For example, differential confocal focusing and off-center masking methods, which convert defocusing into light intensity signals, are easily affected by reflectivity variations. Laser off-centering methods, which calculate defocusing by measuring the centroid of the returned spot, are also subject to fluctuations due to factors such as signal-to-noise ratio.

[0046] In the design of related optical focusing devices, an optical path is led out as a normalized bypass for light intensity, which is used to collect the light intensity reflected from the surface of the object under test (e.g., a wafer). When the reflectivity of the object under test changes, the defocus signal is normalized based on the signal collected by the normalized bypass, reducing the error caused by the change in reflectivity. However, because the reflectivity of the object under test causes large fluctuations in reflected light intensity, low reflectivity areas are prone to insufficient signal-to-noise ratio, and high reflectivity areas are prone to saturation of the detector in the normalized bypass, making it impossible to calibrate the defocus signal based on the signal collected by the normalized bypass to achieve accurate focusing. Therefore, in this application, to ensure that the detector in the normalized bypass maintains effective detection capability across all reflectivity ranges of the object under test, a new semiconductor device is proposed. In this semiconductor device, the power of the light source is adjusted in advance based on the signal collected by the detection component, so that the output power of the light source meets the focusing requirements, ensuring that the second detector (i.e., the detector in the normalized bypass) maintains effective detection capability, thereby achieving accurate calibration of the defocus signal and achieving accurate focusing.

[0047] Example 1

[0048] Figure 1 A schematic diagram of a semiconductor device provided in an embodiment of this application is shown below. Figure 1 As shown, the semiconductor device 1000 includes an optical focusing device 100, a collection system 200, an imaging system 300, a motion stage 12, and a motion control module 11; the collection system 200 is used to gather the light reflected from the object to be tested 10 to the imaging system 300 after the optical focusing device 100 has completed focusing.

[0049] Light source 1 illuminates the object under test 10. The light reflected from the object under test 10 is collected by the collection system 200 and transmitted to the imaging system 300. The image of the object under test 10 acquired by the imaging system 300 can be used for defect detection. To ensure clear imaging by the imaging system 300, focusing is first required by the optical focusing device 100. The motion stage 12 can move along the X-axis (parallel to the plane containing the surface of the object under test 10), the Y-axis (parallel to the plane containing the surface of the object under test 10 and perpendicular to the X-axis), and the Z-axis (perpendicular to the plane containing the surface of the object under test 10 and perpendicular to both the X-axis and Y-axis). The motion stage 12 can also rotate around the Z-axis. The motion control module 11 can not only drive the motion stage 12 to move (or / and rotate) along the X-axis and Y-axis to illuminate different positions of the object under test 10 and realize defect detection at different positions of the object under test 10, but also drive the motion stage 12 to move along the Z-axis to position the object under test 10 at the focal point of the illumination light. Furthermore, to avoid detector saturation or insufficient signal-to-noise ratio caused by the light intensity reflected from the surface of the object under test 10, the optical focusing device 100 provided in this application collects reflectivity change information in advance and adjusts the power of the light source 1 based on the reflectivity change information, thereby ensuring that the detector maintains effective detection capability, improving the accuracy of defocus determination, and thus improving focusing accuracy. After the optical focusing device 100 completes focusing, the imaging system 300 then performs imaging, ensuring clear imaging and thus improving detection accuracy.

[0050] Example 2

[0051] The semiconductor device 1000 provided in the above embodiments integrates an optical focusing device 100 capable of achieving high focusing accuracy. To enable those skilled in the art to better understand the optical focusing device 100 provided in this application, this embodiment provides a detailed description of embodiments of the optical focusing device 100. Figure 2 A structural diagram of an optical focusing device provided in an embodiment of this application is shown below. Figure 2 As shown, the optical focusing device 100 includes: Light source 1, used to provide illumination; Reference modulator 2 is disposed in the transmission optical path of the illumination light and is used to form a first reference beam, a second reference beam, and a first modulated beam; The focusing module 3 is disposed in the post-stage optical path of the reference modulator 2. It is used to project the first reference beam, the second reference beam and the first modulation beam onto the surface of the object under test 10, and to collect the first reference sub-beam, the second reference sub-beam and the first modulation reflection beam generated on the surface of the object under test 10. The first reference sub-beam corresponds to the first reference beam, the second reference sub-beam corresponds to the second reference beam, and the first modulation reflection beam corresponds to the first modulation beam. The beam splitting module 4 is disposed in the post-stage optical path of the focusing module 3 and is used to split the first reference sub-beam, the second reference sub-beam and the first modulated reflection beam into the first detection optical path and the second detection optical path. The complementary modulator 5 is disposed in the first detection optical path and is used to modulate the first modulated reflection beam corresponding to each position point of the focusing module 3 or the motion stage 12 carrying the object to be tested 10 during the scanning process along the preset direction, so as to form a second modulated reflection beam. The first detector 6 is set in the optical path after the complementary modulator 5 to detect the second modulated reflected beam and obtain multiple first photoelectric signals; The detection component 7 is disposed in the second detection optical path and is used to detect the first reference sub-beam or the second reference sub-beam to obtain the second photoelectric signal; The second detector 8 is set in the second detection optical path and is used to detect the first modulated reflected beam corresponding to each position point of the focusing module 3 or the motion stage 12 carrying the object to be tested 10 during the scanning process along the preset direction, so as to obtain multiple third photoelectric signals. The control processing unit 9 is connected to the light source 1, the first detector 6, the detection assembly 7, the second detector 8, and the focusing module 3. The control processing unit 9 is used for: Based on the second photoelectric signal, determine whether the output power of light source 1 meets the focusing requirements; If the output power of light source 1 does not meet the focusing requirements, control light source 1 to adjust its output power; After the output power of the light source 1 meets the focusing requirements, the focusing module 3 or the motion stage 12 carrying the object to be tested 10 is controlled to scan along a preset direction to obtain the first photoelectric signal and the third photoelectric signal corresponding to each position point of the focusing module 3 or the motion stage 12 carrying the object to be tested 10. The first defocusing amount of the object to be tested 10 is determined based on the first photoelectric signal and the third photoelectric signal corresponding to each position point. Based on the first defocus amount, control the focusing module 3 or the motion stage 12 carrying the test object 10 to move so that the surface of the test object 10 is located at the focal point of the first modulated beam.

[0052] Light source 1 can be a light-emitting diode (LED) light source, or a laser light source, or other light sources. The number of light sources 1 can be set to one or more. When a single light source is used, light source 1 is located on one side of the optical axis of the optical focusing device 100. Using a single light source obliquely incident on the reference modulator 2 is low-cost and easy to assemble, which is beneficial for system integration and stable operation. When multiple light sources are used, multiple light sources are obliquely incident on the reference modulator 2 at the same angle around the optical axis along the circumference. When light source 1 is located on the optical axis, the reflected light will return along the original path, forming a stable light spot on the detector. Once defocusing occurs, the center position of the reflected light spot will not change, making it impossible to obtain defocus information from the displacement. However, in this application, light source 1 is located on one side of the optical axis, so that the reflected light path and the incident light path no longer coincide. When the defocusing amount of the objective lens 31 changes, the returned light beam will be incident on the detector at different angles or positions, and the light spot will move laterally accordingly, thereby enabling the acquisition of defocus information.

[0053] Light source 1 provides illumination light, which is collimated by collimating element 13 and then incident on reference modulator 2. The pupil surface of collimating element 13 is located at the reference modulator 2, which ensures uniform illumination and better beam matching, reduces aberrations and stray light, and makes the modulation effect more stable. In the fields of optical focusing and precision detection, optical modulators are often used to constrain and modulate the beam propagation path to achieve functions such as optical path selection, reference marking, and signal calibration. Traditional optical modulators mostly only have a single light intensity modulation function, which can only meet the light transmission and energy control requirements of the main optical path. It is difficult to provide a stable and reliable reference optical path at the same time, resulting in the lack of an effective reference during the focusing process, which easily leads to problems such as focusing deviation and insufficient detection accuracy. Therefore, this application provides a new optical modulator, referred to herein as reference modulator 2. Figure 3 A schematic diagram of a reference modulator provided in an embodiment of this application; Figure 4 A schematic diagram of another reference modulator provided in an embodiment of this application is shown below. Figure 3 or Figure 4 As shown, the reference modulator 2 includes: The first substrate 21 has a first through hole 211 and a second through hole 212. A first modulation section 213 is disposed on a first substrate 21, and a first through hole 211 and a second through hole 212 are located on both sides of the first modulation section 213. The first modulation unit 213 is used to modulate the illumination light to form a first modulation beam, which is used to focus the object 10 under test. The first through hole 211 is used to allow illumination light to pass through in order to form a first reference beam. The first reference beam is used to illuminate the detection area in advance during the process of the test object 10 moving along the first direction, before focusing the detection area of ​​the test object 10 using the first modulated beam, so as to obtain the first surface reflectivity of the detection area through the detection component 7, and then dynamically adjust the working parameters of the light source 1 according to the first surface reflectivity. The second through hole 212 is used to allow illumination light to pass through in order to form a second reference beam. The second reference beam is used to illuminate the area to be detected in advance before the first modulated beam is used to focus the area to be detected of the object to be tested 10 during the movement of the object to be tested 10 along the second direction, so as to obtain the second surface reflectivity of the area to be detected by the detection component 7, and then dynamically adjust the working parameters of the light source 1 according to the second surface reflectivity.

[0054] The reference modulator 2 is located between the light source 1 and the object under test 10. The first substrate 21 serves as the base of the reference modulator 2. The first substrate 21 supports the first modulation section 213, and the first through-hole 211 and the second through-hole 212 on the first substrate 21 are distributed on both sides of the first modulation section 213, achieving positional fixation and layout of each structure based on the substrate. The first through-hole 211 and the second through-hole 212 can be formed at the edge of the first substrate 21, and the first modulation section 213 is formed at the middle of the first substrate 21, such as... Figure 3 and Figure 4As shown. The first through-hole 211 and the second through-hole 212 are symmetrically arranged on both sides of the first modulation section 213. This ensures that the relative spatial position relationship between the first reference beam and the modulation beam, and the relative spatial position relationship between the second reference beams, remains consistent as the object under test 10 moves along the first or second direction. This eliminates measurement errors or response delay differences caused by structural asymmetry, allowing the optical focusing device 100 to dynamically adjust detector parameters based on unified pre-acquired reflectivity data during bidirectional scanning, further guaranteeing consistent focusing accuracy. Furthermore, it should be noted that the first direction refers to the direction from which the projection 2130 of the first modulation section (i.e., the projection position of the first modulation section 213 on the plane where the object under test 10 is located) points to the projection 2110 of the first through-hole (i.e., the projection position of the first through-hole 211 on the plane where the object under test 10 is located) or the projection 2120 of the second through-hole (i.e., the projection position of the second through-hole 212 on the plane where the object under test 10 is located). The second direction refers to the direction from which the projection 2130 of the first modulation section points to the projection 2120 of the second through-hole or the projection 2110 of the first through-hole. The first through-hole 211 and the second through-hole 212 are located on both sides of the first modulation section 213. The centers of the first through-hole 211, the second through-hole 212, and the first modulation section 213 may be on a straight line, or their projections on a plane parallel to the optical axis may partially overlap. The first modulation section 213 has a patterned structure, and the pattern is not limited. For example, the pattern of the first modulation section 213 may be a rectangular ring missing a long side, or it may have a periodic structure, such as a grating (this structure has a light-transmitting area and a light-blocking area, i.e., alternating bright and dark stripes; when incident illumination light passes through this structure, the beam is modulated by the light-transmitting area and the light-blocking area, thereby forming the first modulated beam). The shape of the first modulation section 213 may be square, circular, etc. Figure 3 In the middle, the first modulation unit 213 adopts a circular structure. Figure 4 The first modulation section 213 adopts a square structure. The size and shape of the first through hole 211 and the second through hole 212 are not limited, but determined according to the actual situation. Furthermore, the first through hole 211 and the second through hole 212 can each be a single through hole, such as... Figure 4 As shown; it can also be a through-hole structure composed of multiple through holes, such as Figure 3 As shown.

[0055] The reference modulator provided in this application comprises a first modulation section 213 for modulating illumination light, and a first through-hole 211 and a second through-hole 212 located on both sides of the first modulation section 213. The first through-hole 211 allows illumination light to pass through to form a first reference beam, and the second through-hole allows illumination light to pass through to form a second reference beam. During the movement of the object under test 10 along a first direction, the first reference beam can illuminate the detection area of ​​the object under test 10 before focusing using the first modulation beam, thereby obtaining the first surface reflectivity of the detection area through the detection component 7, and then dynamically adjusting the operating parameters of the light source 1 based on the first surface reflectivity. Similarly, during the movement of the object under test 10 along a second direction opposite to the first direction, the second reference beam can illuminate the detection area of ​​the object under test 10 before focusing using the first modulation beam, thereby obtaining the first surface reflectivity of the detection area through the detection component 7. The second surface reflectance of the detected area is taken, and the operating parameters of the light source 1 are dynamically adjusted according to the second surface reflectance. The first through hole 211 and the second through hole 212 located on both sides of the first modulation unit 213 are used to modulate the illumination light to form a first modulation beam to meet the requirements of the main optical path for light transmission and energy control. At the same time, the above scheme ensures that the surface reflectance change of the test object 10 can be sensed in real time before formal focusing during the bidirectional scanning process of the test object 10. The operating parameters of the light source 1 (such as current, voltage, output power, etc.) are dynamically adjusted according to the surface reflectance change, so that the focusing detector in the optical focusing device 100 can avoid saturation distortion when detecting high reflectance areas and improve the signal-to-noise ratio when detecting low reflectance areas, and always work in the linear response range. This effectively solves the problem of insufficient detection accuracy caused by the drastic change in wafer surface reflectance and significantly improves the overall focusing accuracy of the optical focusing device 100.

[0056] In one possible implementation, the first substrate 21 has a third through-hole 214. The third through-hole 214 is used to accommodate the first modulation section 213. The shape and size of the third through-hole 214 are adapted to the first modulation section 213. By fixing the first modulation section 213 in the third through-hole 214 through adhesive bonding, thread fastening, or other methods, the first modulation section 213 and the through-hole structure on the first substrate 21 can be integrated into the same substrate, effectively reducing the overall structural volume and improving the device integration and structural compactness; at the same time, it can ensure higher relative positional accuracy between the first modulation section 213 and each through-hole, making the assembly more stable and reliable, avoiding the relative positional shift between the main modulation beam and the reference beam due to installation deviation, thereby further ensuring the stability of the optical path reference and improving the accuracy of system focusing and precision detection.

[0057] In addition, in one possible implementation, a transparent substrate is used as the first substrate 21, or the portion of the first substrate 21 on which the first modulation unit 213 is mounted is transparent. The first modulation unit 213 is fixedly mounted on the surface of the first substrate 21. This can ensure that the illumination light can pass smoothly through the substrate to form a reference beam, while providing a flat and stable support for the first modulation unit 213, improving the overall structural rigidity and installation positioning accuracy, and preventing the first modulation unit 213 from shifting or deforming during operation. This ensures that the relative position of the main modulation beam and the two reference beams is stable and reliable, which is beneficial to maintaining the reference stability during the focusing and detection process, and further improving the focusing accuracy and detection reliability of the system.

[0058] To provide a stable and symmetrical reference beam, in implementation, the first through-hole 211 and the second through-hole 212 are symmetrically arranged on both sides of the first modulation section 213. For example... Figure 3 or Figure 4 As shown, by symmetrically arranging the first through-hole 211 and the second through-hole 212 on both sides of the first modulation section 213, a symmetrical dual reference optical path centered on the main modulation beam can be formed. While realizing the modulation function of the main optical path, two stable and symmetrical reference beams are provided simultaneously, providing a balanced and reliable dual reference for the system's focusing and positioning. The symmetrical arrangement can effectively reduce the asymmetry caused by assembly errors and optical path offsets, ensuring good consistency between the two reference optical paths, thereby reducing focusing deviation and improving overall detection accuracy.

[0059] In one possible implementation, the reference modulator 2 is conjugate to the surface of the object under test 10. That is, the first modulated beam emitted by the reference modulator 2 is accurately imaged onto the surface of the object under test 10 after passing through the optical path, and conversely, the surface of the object under test 10 can also be accurately imaged onto the plane of the reference modulator 2. The first modulated beam needs to be clearly projected onto the surface of the object under test 10. Therefore, the reference modulator 2 and the surface of the object under test 10 are conjugate to ensure that the first modulated beam forms a clear periodic pattern on the surface of the object under test 10, providing an accurate optical signal for subsequent photoelectric signal acquisition and processing.

[0060] A focusing module 3 is provided in the optical path following the reference modulator 2. The focusing module 3 is either an objective lens 31 or a focusing assembly 32, located in the optical path between the reference modulator 2 and the object under test 10. Alternatively, the focusing module 3 may consist of a focusing assembly 32 and an objective lens 31, which are sequentially positioned in the optical path between the reference modulator 2 and the object under test 10. Figure 2As shown, the focusing assembly 32 includes a focusing motor 321 and a focusing lens 322. The objective lens 31 moves along the optical path axis, changing the optical path and optical path of the beam, so that the beam is focused on the surface of the object 10 to complete focusing. The focusing assembly 32 is adjusted along the optical path displacement to change the convergence and divergence state and the focusing position of the beam, thereby achieving focusing. The optical focusing device 100 can serve the imaging system 300. Figure 5 As shown, Figure 5 This is a schematic diagram illustrating an optical focusing device used in conjunction with an imaging system according to an embodiment of this application. The imaging system 300 includes an objective lens 31, an imaging module 30001, and a beam splitter 30002. Furthermore, it should be noted that... Figure 5 The optical focusing components include a light source 1, a reference modulator 2, a beam splitting module 4, a focusing module 3, a complementary modulator 5, a first detector 6, a second detector 8, and a detection component 7.

[0061] The focusing module 3, disposed in the post-stage optical path of the reference modulator 2, is used to project the first reference beam, the second reference beam, and the first modulation beam onto the surface of the object under test 10, and to collect the first reference sub-beam, the second reference sub-beam, and the first modulation reflected beam generated on the surface of the object under test 10. The first reference sub-beam corresponds to the first reference beam, the second reference sub-beam corresponds to the second reference beam, and the first modulation reflected beam corresponds to the first modulation beam. That is, the first reference beam is reflected by the surface of the object under test 10 to form the first reference sub-beam, the second reference beam is reflected by the surface of the object under test 10 to form the second reference sub-beam, and the first modulation beam is reflected by the surface of the object under test 10 to form the first modulation reflected beam.

[0062] The beam splitting module 4 is disposed in the post-stage optical path of the focusing module 3 and is used to split the first reference sub-beam, the second reference sub-beam and the first modulated reflection beam into the first detection optical path and the second detection optical path. Figure 2 In this system, the beam splitting module 4 includes a first beam splitter element 41 and a second beam splitter element 42. Both the first beam splitter element 41 and the second beam splitter element 42 can be polarizing beam splitters. The first beam splitter element 41 and the second beam splitter element 42 are sequentially located in the subsequent optical path of the focusing module 3. The first beam splitter element 41 first reflects the first reference sub-beam, the second reference sub-beam, and the first modulated reflection beam to the second beam splitter element 42, and the second beam splitter element 42 transmits the first modulated reflection beam to form a first detection optical path; the second beam splitter element 42 reflects the first reference sub-beam and the second reference sub-beam to form a second detection optical path. In addition, it is worth noting that the first beam splitter element 41 is also located between the reference modulator 2 and the focusing module 3, and the first beam splitter element 41 transmits the first reference beam, the second reference beam, and the first modulated beam to the focusing module 3.

[0063] In addition to the reference modulator 2, the optical focusing device 100 also includes a complementary modulator 5 on the first probe light path split by the beam splitting module 4. Specifically, Figure 2 In this configuration, the complementary modulator 5 is disposed between the beam splitting module 4 and the first focusing element 14. The complementary modulator 5 works in conjunction with the aforementioned reference modulator 2 and is applied in the optical focusing device 100 provided in the above embodiment, which is used to focus on the object 10. Figure 6 This is a schematic diagram of a complementary modulator provided in an embodiment of this application. Figure 7 This is a schematic diagram of another complementary modulator provided in an embodiment of this application. Figure 6 or Figure 7 As shown, the complementary modulator 5 includes: The second substrate 51 is the base of the complementary modulator 5 and is used to mount the blocking portion and the second modulation portion 513. The second substrate 51 has a first blocking portion 511 and a second blocking portion 512. The size of the first blocking portion 511 is larger than the size of the first through-hole 211, and the size of the second blocking portion 512 is larger than the size of the second through-hole 212. The shape of the first blocking portion 511 is adapted to the first through-hole 211, and the shape of the second blocking portion 512 is adapted to the second through-hole 212. Furthermore, the second substrate 51 is opaque, and the first blocking portion 511 and the second blocking portion 512 are part of the second substrate 51. The first blocking portion 511 corresponds to the position of the first through-hole 211 and is used to block the first reference sub-beam generated after the first reference beam is incident on the test object 10 from passing through. It should be noted that the correspondence between the first blocking part 511 and the first through hole 211 specifically means that the first blocking part 511 and the first through hole 211 have a specific alignment relationship in a preset direction (usually a plane perpendicular to the optical axis), and the first blocking part 511 exactly blocks the first through hole 211. The second blocking part 512 corresponds to the second through hole 212 and is used to block the second reference sub-beam generated after the second reference beam is incident on the test object 10. The correspondence between the second blocking part 512 and the second through hole 212 specifically means that the second blocking part 512 and the second through hole 212 have a specific alignment relationship in a preset direction (usually a plane perpendicular to the optical axis), and the second blocking part 512 exactly blocks the second through hole 212. Figure 6 The provided complementary modulator 5 is the same as the one described above. Figure 3 Used in conjunction with reference modulator 2; Figure 7 The provided complementary modulator 5 is the same as the one described above. Figure 5 It is used in conjunction with the reference modulator 2.

[0064] The second modulation unit 513 is disposed on the second substrate 51. The second modulation unit 513 and the first modulation unit 213 are offset from each other on the pupil surface or conjugate surface, such as by 1 / 2 grating period. The second modulation unit 513 is used to modulate the first modulation reflection beam generated after the first modulation beam is incident on the test object 10 to form the second modulation reflection beam.

[0065] The first modulation section 213 and the second modulation section 513 have the same size, structure and type, except that they are offset in one direction and the amount of offset is no greater than one period of the periodic pattern. In the complementary modulator 5, by setting a first blocking part 511 corresponding to the position of the first through hole 211 and a second blocking part 512 corresponding to the position of the second through hole 212, the first reference sub-beam generated by the reflection of the first reference beam by the test object 10 and the second reference sub-beam generated by the reflection of the second reference beam by the test object 10 can be accurately intercepted. At the same time, the second modulation part 513 is mounted on the second substrate 51 and is staggered with the first modulation part 213 on the pupil surface or conjugate surface, so that the second modulation part 513 can perform secondary modulation on the first modulation reflected beam to generate the second modulation reflected beam. The above settings fundamentally eliminate the noise superposition and signal crosstalk caused by the mixing of the first reference sub-beam and the second reference sub-beam into the second modulation reflected beam, significantly improve the purity and signal-to-noise ratio of the detector received signal in the optical focusing device 100, and further ensure the focusing accuracy and stability of the optical focusing system in complex reflectivity environments.

[0066] In one possible implementation, the second substrate 51 has a fourth through hole 514. The fourth through hole 514 is used to accommodate the second modulation section 513. The shape and size of the fourth through hole 514 are adapted to the second modulation section 513. By fixing the second modulation section 513 into the fourth through hole 514 through methods such as adhesive bonding or threaded fastening, the second modulation section 513 and the blocking structure on the second substrate 51 can be integrated into the same substrate. This improves the overall integration and structural compactness of the device, while ensuring higher relative positional accuracy between the second modulation section 513 and the blocking sections on both sides. The assembly is more stable and reliable, effectively avoiding problems such as optical path misalignment and signal crosstalk caused by installation gaps or positional offsets. This ensures stable and accurate modulation of the main modulation reflected beam, further improving the reliability and accuracy of optical focusing and precision detection.

[0067] In one possible implementation, the second substrate 51 is a transparent substrate, or the portion of the second substrate 51 on which the second modulation section 513 is mounted is transparent. The second modulation section 513 is fixedly mounted on the surface of the second substrate 51, and the first blocking section 511 and the second blocking section 512 are fixedly mounted on the surface of the second substrate 51. Using a transparent substrate for the second substrate 51, and fixing the second modulation section 513, the first blocking section 511, and the second blocking section 512 on its surface, ensures normal transmission of the light beam, preventing the substrate itself from blocking or causing loss to the effective optical path. It also provides a flat and uniform mounting surface for the second modulation section 513 and the two blocking sections, resulting in higher relative positional accuracy between the functional structures, a more stable and reliable overall structure, and effectively reducing the risk of optical path misalignment caused by assembly errors. Simultaneously, it facilitates precise optical path coordination with the reference modulator 2, reliably modulating the main modulation reflected beam and blocking the reference sub-beam, while ensuring a stable focusing reference, further improving the system's focusing accuracy and detection stability.

[0068] In the optical focusing device provided in this application, the complementary modulator 5 is disposed in the first detection optical path. The second modulation part 513 of the complementary modulator 5 modulates the first modulation reflection beam corresponding to each position point of the focusing module 3 or the motion stage 12 carrying the object to be tested 10 during scanning along a preset direction to form the second modulation reflection beam.

[0069] In one possible implementation, the conjugate surface of the reference modulator 2 is conjugate with that of the complementary modulator 5. The complementary modulator 5 is used to further modulate the reflected image of the reference modulator 2. The conjugate relationship between the complementary modulator 5 and the conjugate surface of the reference modulator 2 ensures that the image of the reference modulator 2 can clearly form a second modulated reflected beam on the complementary modulator 5, providing an accurate optical signal for subsequent photoelectric signal acquisition and processing.

[0070] In the subsequent optical path of the complementary modulator 5, a first detector 6 is also provided. The first detector 6 can be a photodiode, a complementary metal-oxide-semiconductor (CMOS) image sensor, etc. The first detector 6 is used to detect the second modulated reflected beam and obtain multiple first photoelectric signals. The first photoelectric signals include defocus signals and signals reflected by the object under test 10. In implementation, a first focusing element 14 can be provided between the complementary modulator 5 and the first detector 6, so that the second modulated reflected beam is collimated by the first focusing element 14 and then received by the first detector 6.

[0071] In order to more accurately determine the defocus signal and improve the focusing accuracy, in this application, in addition to detecting the first photoelectric signal through the first detection optical path mentioned above, a detection component 7 is also provided on the second detection optical path. Figure 8 This is a schematic diagram of a detection component 7 provided in an embodiment of this application. The detection component 7, used in conjunction with the aforementioned reference modulator 2, includes: Mounting plate 71, the mounting plate 71 has a fifth through hole 711, for the first modulated reflected beam generated after the first modulated beam is incident on the object under test 10 to pass through; The first detection element 712 can be a photodiode, CMOS image sensor, etc. The first detection element 712 is mounted on the mounting plate 71, specifically fixed by means of snap-fit, screw tightening, or adhesive bonding to ensure stability. The first detection element 712 corresponds to the position of the first through-hole 211 and is used to receive the first reference sub-beam generated after the first reference beam is incident on the object under test 10. Specifically, the correspondence between the first detection element 712 and the first through-hole 211 means that the installation or sensing position of the first detection element 712 is aligned with the geometric center or specific opening area of ​​the first through-hole 211 in a preset direction to ensure that the first reference beam can pass through accurately.

[0072] The second detection element 713 can be a photodiode, CMOS image sensor, etc. The second detection element 713 is mounted on the mounting plate 71, specifically fixed by means of snap-fit, screw tightening, or adhesive bonding to ensure stability. The second detection element 713 corresponds to the position of the second through-hole 212 and is used to receive the second reference sub-beam generated after the second reference beam is incident on the object under test 10. Specifically, the correspondence between the second detection element 713 and the second through-hole 212 means that the installation or sensing position of the second detection element 713 is aligned with the geometric center or specific opening area of ​​the second through-hole 212 in a preset direction to ensure that the second reference sub-beam can pass through accurately.

[0073] The detection component 7 works in conjunction with the reference modulator 2. A fifth through hole 711 is provided on the mounting plate 71 to allow the first modulated reflected beam of the main optical path to pass through. At the same time, a first detection element 712 and a second detection element 713 are provided corresponding to the positions of the first through hole 211 and the second through hole 212.

[0074] The detection assembly 7 includes a mounting plate 71, a first detection element 712, and a second detection element 713. A fifth through-hole 711 in the mounting plate 71 is specifically designed for the passage of the first modulated reflected beam, allowing it to enter the subsequent imaging or main detection optical path without being obstructed by the reference optical path elements. Simultaneously, the first detection element 712 and the second detection element 713 are precisely positioned corresponding to the first through-hole 711 and the second through-hole 712, respectively. This ensures that when the object under test 10 moves along the first or second direction, the first detection element 712 can independently and in real-time acquire the first reference sub-beam formed by the reflection of the first reference beam and the second detection element 713. 13 can independently and in real time acquire the second reference sub-beam formed by the reflection of the second reference beam. In this way, no matter which direction the object under test 10 is scanned, the system can acquire the surface reflectivity data of the detected area in real time before formal focusing through the corresponding detection element, eliminating the blind zone of unidirectional detection and ensuring the continuity and full coverage of focusing parameter adjustment. In addition, by physically isolating the first reference sub-beam and the second reference sub-beam from the first modulated reflected beam at the optical path receiving end, the saturation interference or crosstalk of strong reference light to the main detection channel is effectively avoided, ensuring the high signal-to-noise ratio of the main detection signal, and also ensuring the independence and accuracy of the reference light signal.

[0075] By detecting the first reference sub-beam or the second reference sub-beam through the detection component 7 disposed in the second detection optical path, a second photoelectric signal can be obtained. This second photoelectric signal is the reflection signal of the object under test 10. In this application, the change in reflectivity of the object under test 10 can be determined through the second photoelectric signal, that is, the second photoelectric signal can also be called the reflectivity change signal.

[0076] In one possible implementation, the photosensitive surface of the detector component 7 is conjugate to the conjugate surface of the reference modulator 2. The conjugate relationship between the conjugate surface of the reference modulator 2 and the photosensitive surface of the detector component 7 ensures that the image of the reference modulator 2 can be clearly formed on the first detector element 712 and the second detector element 713, providing accurate optical signals for subsequent photoelectric signal acquisition and processing.

[0077] In addition to the detection component 7 in the second detection optical path, a second detector 8 is also provided. The second detector 8 can be a photodiode, a CMOS image sensor, etc. The second detector 8 is used to detect the first modulated reflected beam corresponding to each position point during the scanning process of the focusing module 3 or the motion stage 12 carrying the object under test 10 along a preset direction, and obtain multiple third photoelectric signals.

[0078] In one possible implementation, such as Figure 2As shown, the second detector 8 is disposed in the subsequent optical path of the detection component 7. In implementation, a second focusing element 15 can be disposed between the second detector 8 and the detection component 7, so that the first modulated reflected beam is collimated by the second focusing element 15 and then received by the second detector 8.

[0079] Based on the accurate reception and transmission of the first reference sub-beam and the second reference sub-beam by the detection component 7 to provide a stable reference signal, the second detector 8 can specifically receive the first modulated reflected beam after transmission through the optical path of the detection component 7. This avoids signal crosstalk between the first modulated reflected beam and the reference sub-beam during transmission, ensuring that the second detector 8 can accurately capture the third photoelectric signal corresponding to each position point. In addition, the second detector 8 is set in the subsequent optical path of the detection component 7, so that the detection component 7 receives the first reference sub-beam or the second reference sub-beam earlier than the second detector 8 receives the first modulated reflected beam. As a result, the power of the light source 1 can be adjusted in advance based on the signal collected by the detection component 7, so that the output power of the light source 1 meets the focusing requirements. This avoids the insufficient signal-to-noise ratio caused by the low reflectivity area of ​​the test object 10, which leads to insufficient effective signal received by the second detector 8, and the saturation of the second detector 8 caused by the high reflectivity area. This ensures that the second detector 8 in the optical focusing device can maintain effective detection capability across all reflectivity ranges of the test object 10, expanding the matching capability of the optical focusing device for test objects 10 with different reflectivities.

[0080] The control processing unit 9 can be a computer processing system, specifically including an industrial control computer, a microcontroller, etc. The control processing unit 9 is connected to the light source 1, the first detector 6, the detection component 7, the second detector 8, and the focusing module 3. It is used to determine whether the output power of the light source 1 meets the focusing requirements based on the second photoelectric signal; if the output power of the light source 1 does not meet the focusing requirements, it controls the light source 1 to adjust its output power; after the output power of the light source 1 meets the focusing requirements, it controls the focusing module 3 or the motion stage 12 carrying the object under test 10 to scan along a preset direction; it acquires the first photoelectric signal and the third photoelectric signal corresponding to each position point of the focusing module 3 or the motion stage 12 carrying the object under test 10; based on the first photoelectric signal and the third photoelectric signal corresponding to each position point, it determines the first defocus amount of the object under test 10; based on the first defocus amount, it controls the focusing module 3 or the motion stage 12 carrying the object under test 10 to move, so that the surface of the object under test 10 is located at the focal point of the first modulated beam.

[0081] Because the control processing unit 9 adjusts the power of the light source 1 in advance based on the signal collected by the detection component 7, the output power of the light source 1 meets the focusing requirements, ensuring that the second detector 8 maintains effective detection capability, that is, ensuring the effectiveness of the third photoelectric signal. Therefore, after the output power of the light source 1 meets the focusing requirements, the focusing module 3 or the motion stage 12 carrying the object to be tested 10 is controlled to scan along a preset direction to acquire the first photoelectric signal and the third photoelectric signal corresponding to each position point of the focusing module 3 or the motion stage 12 carrying the object to be tested 10. When determining the first defocus amount of the object to be tested 10 based on the first photoelectric signal and the third photoelectric signal corresponding to each position point, the accuracy of the determination of the first defocus amount is improved. Finally, because the determined first defocus amount is relatively accurate, when the focusing module 3 or the motion stage 12 carrying the object to be tested 10 is controlled to move according to the first defocus amount, focusing can be completed more accurately, thus improving the focusing accuracy.

[0082] Additionally, it should be noted that the preset direction specifically refers to the direction perpendicular to the optical axis. Based on the first and third photoelectric signals corresponding to each position point, the first defocus amount is determined. Then, based on the first defocus amount, the focusing module 3 or the motion stage 12 carrying the object under test 10 is moved, so that the surface of the object under test 10 is located at the focal point of the first modulated beam. The control processing unit 9 can be connected to the motion control module 11, and the motion control module 11 is connected to the motion stage 12, such as... Figure 5 As shown, the control processing unit 9 can send motion control to the motion table 12 through the motion control module 11, thereby controlling the movement of the motion table 12.

[0083] When the focusing module 3 is the objective lens 31, by moving the objective lens 31 along the optical path axis, the converging optical path and optical path of the beam emitted from the reference modulator 2 are changed, so that the beam is precisely focused on the surface of the object under test 10, thereby achieving system focusing by adjusting the position of the objective lens 31. When the focusing module 3 is a focusing assembly 32 including a focusing motor 321 and a focusing lens 322, the focusing motor 321 drives the focusing lens 322 to make displacement adjustment along the optical path direction, changing the optical incident position of the focusing lens 322, thereby controlling the convergence and divergence of the beam and the focusing position to achieve focusing. Alternatively, the motion stage 12 carrying the object under test 10 is controlled to translate back and forth along the main optical axis of the optical path, so that the surface of the object under test 10 is located at the focal point of the first modulated beam.

[0084] The optical focusing device provided in this embodiment uses a reference modulator 2 to simultaneously generate a first modulated beam, a first reference beam, and a second reference beam. This beam, along with a focusing module 3, is projected onto the surface of the object under test 10 and the corresponding reflected beams are collected. The beams are then split and transmitted via a beam splitter 4, achieving independent transmission and collaborative operation between the main modulated optical path and the reference optical path. The complementary modulator 5 and the first detector 6 process the first modulated reflected beam formed by the reflection of the first modulated beam from the object under test 10 to form a second modulated reflected beam and obtain a first photoelectric signal. The second detector 8 directly acquires the first modulated reflected beam corresponding to each position point to obtain a third photoelectric signal. The detection component 7 specifically receives the reflected sub-beams corresponding to the two reference beams and outputs a second photoelectric signal. While retaining the main optical path focusing detection function, a stable and reliable reference standard is introduced simultaneously, fundamentally solving the technical problems of traditional optical modulators being unable to provide an effective reference optical path, prone to focusing deviations, and lacking detection accuracy. Furthermore, the control processing unit 9 can determine whether the output power of the light source 1 meets the focusing requirements based on the second photoelectric signal detected by the detection component 7. If the output power of the light source 1 does not meet the focusing requirements, the control unit 9 adjusts the output power of the light source 1. This avoids insufficient signal-to-noise ratio caused by low reflectivity areas of the test object 10, resulting in insufficient effective signal received by the second detector 8, and saturation of the second detector 8 caused by high reflectivity areas. This ensures that the second detector 8 in the optical focusing device can maintain effective detection capability across all reflectivity ranges of the test object 10, expanding the matching capability of the optical focusing device for test objects 10 with different reflectivity. In addition, since the power of the light source 1 is adjusted in advance based on the signal collected by the detection component 7, the output power of the light source 1 meets the focusing requirements. The focus requirement ensures that the second detector 8 maintains effective detection capability, thus ensuring the effectiveness of the third photoelectric signal. Furthermore, after the output power of the light source 1 meets the focusing requirement, the focusing module 3 or the motion stage 12 carrying the object to be tested 10 is controlled to scan along a preset direction, acquiring the first and third photoelectric signals corresponding to each position point of the focusing module 3 or the motion stage 12 carrying the object to be tested 10. When determining the first defocus amount of the object to be tested 10 based on the first and third photoelectric signals corresponding to each position point, the accuracy of the first defocus amount determination is improved. Finally, because the determined first defocus amount is relatively accurate, when controlling the movement of the focusing module 3 or the motion stage 12 carrying the object to be tested 10 based on this first defocus amount, focusing can be completed more precisely, improving focusing accuracy.

[0085] Example 3

[0086] The foregoing description includes a semiconductor device and an optical focusing apparatus. This embodiment also provides a focusing control method applied to the aforementioned optical focusing apparatus. The embodiments of the optical focusing apparatus have been described in detail above. In this embodiment, for technical features identical to those in the optical focusing apparatus embodiments, please refer to the description above; they will not be repeated here. Figure 9 A flowchart of a focus control method provided in an embodiment of this application is shown below. Figure 9 As shown, the method includes: S10: Acquire the second photoelectric signal; Before acquiring the second photoelectric signal, in order to detect the object 10 to be tested, such as... Figure 5 As shown, the control unit 16 (such as a computer system) can be connected to the motion control module 11 to send motion commands to the motion control module 11. The control unit 16 is also connected to the control processing unit 9 to send an adaptive reflectivity change enable to the control processing unit 9, that is, to enable the function of automatically adapting to the reflectivity change of the test object 10.

[0087] As described above, after detecting the first or second reference sub-beam by the detection component 7, a second photoelectric signal is obtained. The control processing unit 9 then acquires the second photoelectric signal collected by the detection component 7.

[0088] It should be noted that, in order to match the time of power change of light source 1 with the time of scanning different reflectivity regions of the wafer, before acquiring the second photoelectric signal, the calibration of the transmission time of the signal used to characterize the adjustment of the output power of light source 1 is also included. In one possible implementation, before acquiring the second photoelectric signal, the following is also included: Determine the timing of the target signal transmission, where the target signal is a signal used to characterize the adjustment of the output power of light source 1.

[0089] In implementation, the timing of the target signal transmission is determined, including: The distance between the first modulation section 213 in the reference modulator 2 and the target through hole, the projection magnification of the reference modulator 2, the scanning rate, and the communication delay between itself and the light source 1 are obtained; wherein, the target through hole is either the first through hole 211 or the second through hole 212; The target signal transmission time is determined based on the distance between the first modulation unit 213 and the target through-hole, the projection magnification of the reference modulator 2, the scanning rate, and the communication delay between the control processing unit 9 and the light source 1. The distance between the first modulation unit 213 and the target through-hole is the distance between the center of the first modulation unit 213 and the center of the target through-hole. The projection magnification of the reference modulator 2 refers to the ratio between the image size formed on the plane (i.e., the image plane) of the object under test 10 after the pattern on the first modulation unit 213 is projected onto the object under test 10, and the actual size of the corresponding pattern on the first modulation unit 213. When determining this magnification, a pattern with a known size (such as a single stripe) on the first modulation unit 213 is selected, its image size on the image plane is measured, and the image size is divided by the actual size of the pattern to obtain the projection magnification. The scanning rate refers to the distance the object under test 10 moves per unit time when it is scanned by the motion stage 12.

[0090] Specifically, the target signal transmission time is determined based on the distance between the first modulation unit 213 and the target through-hole, the projection magnification of the reference modulator 2, the scanning rate, and the communication delay time between itself and the light source 1, including: The response time difference is calculated based on the distance between the first modulation unit 213 and the target through hole, the projection magnification and the scanning rate. The response time difference is the distance between the first modulation unit 213 and the target through hole divided by the product of the projection magnification and the scanning rate. Subtracting the communication delay from the response time difference yields the target signal transmission time.

[0091] Assuming the distance between the first modulation unit 213 and the target through-hole is l, the projection magnification of the reference modulator 2 is α, the scanning rate is v, and the communication delay between itself (i.e., the control processing unit 9) and the light source 1 is t_c, then the response time difference Δt is: Δt = l / (α v); considering communication delay, the target signal transmission time is Δt-t_c.

[0092] After calibrating the transmission time of the signal used to characterize the output power of the light source 1, in order to improve focusing efficiency, in one possible implementation, before acquiring the second photoelectric signal, the following steps are taken: acquiring a first image of the surface of the object under test 10 using a camera; determining the defocus amount of the object under test 10 based on the first image; and controlling the movement of the motion stage 12 according to the defocus amount to perform preliminary focusing on the object under test 10. The camera is included in the imaging system described above. After acquiring the image of the object under test 10, the image edge texture, detail contrast, and other sharpness features are extracted and compared with the sharpness reference benchmark preset by the system. Based on this, the offset direction and degree of the object under test 10 relative to the beam focus are determined, and the corresponding defocus amount is calculated. Then, the motion stage 12 carrying the object under test 10 is driven to adjust its position along the optical axis according to the obtained defocus amount, reducing the distance between the object under test 10 and the focus, and completing the preliminary focusing of the object under test 10.

[0093] Since the object under test 10 is initially focused before acquiring the second photoelectric signal, it provides a foundation for subsequent high-precision focusing and improves focusing efficiency. In addition, the camera acquires a first image of the surface of the object under test 10; the defocus amount of the object under test 10 is determined based on the first image; the motion stage 12 is controlled to move based on the defocus amount to perform initial focusing on the object under test 10. This eliminates the need for repeated manual adjustment of the focus position, enabling automated control of the focusing process, quickly reducing defocus deviation, and further improving focusing efficiency.

[0094] After initial focusing of the object 10 is completed, film scanning begins. To avoid invalid focusing operations and reduce resource waste, in one possible implementation, after initial focusing of the object 10 and before acquiring the second photoelectric signal, the following steps are also included: Once the scanning starts, the relationship between the test object 10 and the field of view of the objective lens 31 in the focusing module 3 is obtained. If the object to be tested 10 is detected to be outside the field of view of objective lens 31, the focusing operation will not be performed.

[0095] During target row scanning, the test object 10 is controlled to move along the projection position of the target through hole on the plane where the test object 10 is located towards the projection position of the first modulation unit 213 on the plane where the test object 10 is located. When the test object 10 is detected to have moved to the projection position of the target through hole of the reference modulator 2 on the plane where the test object 10 is located, the detection element in the detection assembly 7 corresponding to the target through hole is controlled to detect the target reference sub-beam and proceed to the step of acquiring the second photoelectric signal. Among them, when scanning adjacent rows of the target row, the movement direction of the test object 10 is opposite, the target through hole is the first through hole 211 or the second through hole 212, and the target reference sub-beam is the first reference sub-beam or the second reference sub-beam.

[0096] Figure 10This application provides a schematic diagram of the motion trajectory of a motion table, as shown in the embodiment of the present application. Figure 10 As shown, the motion trajectory of the motion table 12 is Z-shaped, and the motion trajectory of the object to be tested 10 is also Z-shaped under the action of the motion table 12. Figure 11 This is a schematic diagram illustrating the correspondence between the projected positions of the object under test and the reference modulator when the motion stage moves in a first direction, as provided in an embodiment of this application. It is assumed that the first through-hole 211 and the second through-hole 212 are of identical size, such as having a light-transmitting aperture diameter of d, and are symmetrically distributed on both sides of the first modulation section 213. Figure 11 As shown, when the motion stage 12 moves in the first direction, the object under test 10 moves along the projection position of the first through hole 211 on the plane where the object under test 10 is located (hereinafter referred to as the first through hole projection 2110) towards the projection position of the first modulation unit 213 on the plane where the object under test 10 is located (hereinafter referred to as the first modulation unit projection 2130). The object under test 10 first passes through the projection position of the first through hole 211 on the plane where the object under test 10 is located. Since the first detection element 712 corresponds to the first through hole 211 and the first reference sub-beam corresponds to the first through hole 211, the first detection element 712 is controlled to detect the first reference sub-beam. After the first detection element 712 receives the first reference sub-beam, its internal photosensitive structure is excited by photons to generate photogenerated charges, converting the light intensity information of the beam into the corresponding current or voltage signal, completing the conversion from optical signal to electrical signal, and finally outputting the second photoelectric signal. Figure 12 This is a schematic diagram illustrating the correspondence between the projected positions of the object under test and the reference modulator when the motion stage moves in a second direction, as provided in an embodiment of this application. Figure 12 As shown, when the motion stage 12 moves in the second direction, the object under test 10 moves along the projection position of the second through hole 212 on the plane where the object under test 10 is located (hereinafter referred to as the second through hole projection 2120) towards the projection position of the first modulation unit 213 on the plane where the object under test 10 is located (hereinafter referred to as the first modulation unit projection 2130). The object under test 10 first passes through the projection position of the second through hole 212 on the plane where the object under test 10 is located. Since the second detection element 713 corresponds to the second through hole 212 and the second reference sub-beam corresponds to the second through hole 212, the second detection element 713 is controlled to detect the second reference sub-beam. After receiving the second reference sub-beam, the photosensitive structure inside the second detection element 713 is excited by photons to generate photogenerated charges, converting the light intensity information of the beam into the corresponding current or voltage signal, completing the conversion from optical signal to electrical signal, and finally outputting the second photoelectric signal.

[0097] Since the projection of the reference modulator 2 onto the plane where the object under test 10 is located is a certain area, this area may correspond to multiple reflectivity regions of the object under test 10. Different reflectivities will cause differences in reflected light intensity, thereby interfering with the acquisition accuracy of the photoelectric signal. Therefore, in order to improve the accuracy of the determined second photoelectric signal, in one possible implementation, acquiring the second photoelectric signal includes: When illumination light is incident into the target through hole, the detection component 7 collects multiple second photoelectric signals within a target time; wherein, the target time is the ratio of the diameter d of the target through hole to the scanning speed v, and the target through hole is either the first through hole 211 or the second through hole 212. Calculate the average of multiple second photoelectric signals, and use the average of multiple second photoelectric signals as the final second photoelectric signal.

[0098] Assuming the target time is represented by T, then the target time is T = d / v. In this embodiment, the acquired signal will be averaged over a time interval of d / v, and the average of multiple second photoelectric signals will be transmitted, i.e., the second photoelectric signal... . Figure 13 This is a schematic diagram illustrating data averaging as provided in an embodiment of this application. In practice, the number of data sets (second photoelectric signals) selected for averaging is not limited. Figure 13 In this embodiment, the average of every three sets of data (i.e., the second photoelectric signal) is taken. The target time is first determined based on the ratio of the diameter of the target through hole to the scanning rate, and then the average of the multiple second photoelectric signals collected by the detection component 7 within the target time is used as the final second photoelectric signal, which improves the accuracy of the determined second photoelectric signal.

[0099] In addition, to verify the accuracy of the second photoelectric signal, during implementation, the signal collected by the second detector 8 after the target signal is transmitted is obtained; if the average value of the signal collected by the detection module within the target time is found to be in a constant proportional relationship with the signal collected by the second detector 8, then the second photoelectric signal transmitted is determined to be correct.

[0100] S11: Based on the second photoelectric signal, determine whether the output power of the light source meets the focusing requirements; if not, proceed to step S12; if yes, proceed to step S13. Based on the second photoelectric signal, determine whether the output power of light source 1 meets the focusing requirements, including: The first ideal voltage value corresponding to the second detector 8 is determined based on the characteristics of the second detector 8; wherein, the characteristics of the second detector 8 include photoelectric response characteristics, linear operating range, etc. Obtain the ratio between the first ideal voltage value and the second photoelectric signal; Based on the ratio result, determine whether the output power of light source 1 meets the focusing requirements.

[0101] Specifically, in implementation, determining whether the output power of light source 1 meets the focusing requirements based on the ratio result includes: acquiring the first measured voltage value measured by the second detector 8 and the second measured voltage value measured by the detection component 7 on the surface of the test object with consistent reflectivity; calculating the proportionality coefficient, where the proportionality coefficient is the ratio of the first measured voltage value to the second measured voltage value; and determining the current value corresponding to the second photoelectric signal based on the product of the ratio result, the proportionality coefficient, and the current value of light source 1 when the illumination light is incident on the target through-hole. If the current value corresponding to the second photoelectric signal is detected within the current threshold range, it is determined that the output power of light source 1 meets the focusing requirements; if the current value corresponding to the second photoelectric signal is detected outside the current threshold range, it is determined that the output power of light source 1 does not meet the focusing requirements. The current threshold range characterizes the current range when light source 1 is operating normally. Furthermore, it should be noted that when the test object 10 is a wafer, a test object with consistent reflectivity is selected as a wafer with consistent reflectivity. The selected wafer with consistent reflectivity is a bare silicon wafer or a wafer covered with a uniform oxide layer, and its surface reflectivity fluctuation range is less than ±5%.

[0102] S12: Control the light source to adjust its output power and return to step S10; If, based on the second photoelectric signal, it is determined that the output power of light source 1 does not meet the focusing requirements, the control processing unit 9 controls light source 1 to adjust its output power. To reasonably adjust the output power of light source 1, in one possible implementation, before controlling light source 1 to adjust its output power, the following steps are also included: The first ideal voltage value corresponding to the second detector 8 is determined based on its characteristics, and the actual voltage value measured by the detection component 7 is obtained. On the surface of the test object with consistent reflectivity, the first measured voltage value measured by the second detector 8 and the second measured voltage value measured by the detection component 7 are obtained respectively. Calculate the proportionality coefficient, where the proportionality coefficient is the ratio of the first measured voltage value to the second measured voltage value; The adjustment current value of light source 1 is determined based on the first ideal voltage value, the actual voltage value, the proportional coefficient, and the current value of light source 1 when the illumination light is incident on the target through hole.

[0103] Specifically, based on the first ideal voltage value, the actual voltage value, the proportional coefficient, and the current value of light source 1 when the illumination light is incident on the target through-hole, the adjustment current value of light source 1 is determined, including: Obtain the ratio of the first ideal voltage value to the actual voltage value; The adjustment current value of light source 1 is obtained by multiplying the ratio of the first ideal voltage value to the actual voltage value with the proportionality coefficient and the current value of light source 1 when the illumination light is incident on the target through hole.

[0104] The actual voltage value measured by the detection component 7 is the second photoelectric signal described above. The power of light source 1 is limited during its normal operating range, necessitating the establishment of a normal operating range. Within this range, it is expected that the signal acquired by the second detector 8 will remain at a relatively stable level. This refers to the first ideal voltage value. The first measured voltage value N-PD and the second measured voltage value Det-PD are measured on a flat surface with uniform reflectivity, respectively, with a proportionality coefficient k = N-PD / Det-PD. It can be assumed that the signal on detector 7 is received Δt earlier than the signal on the second detector 8. The signal on detector 7 reflects the upcoming change in reflectivity, therefore the current after Δt can be predicted, i.e., the adjustment current value of light source 1. The adjustment current value of light source 1. The calculation formula is: ; in, This represents the current value of light source 1 when the illumination light is incident on the target through-hole. This represents the proportionality coefficient.

[0105] After calculating the adjustment current value of the light source 1, the control processing unit 9 sends a power adjustment signal of the light source 1 containing the adjustment current value of the light source 1. The operating current of the light source 1 is directly controlled by the power adjustment signal of the light source 1, thereby changing the luminous intensity of the light source 1 and thus completing the adjustment of the output power of the light source 1.

[0106] S13: Control the focusing module or the motion stage carrying the object to be tested to scan along a preset direction, and acquire the first photoelectric signal and the third photoelectric signal corresponding to each position point of the focusing module or the motion stage carrying the object to be tested.

[0107] After determining from the second photoelectric signal that the output power of the light source 1 meets the focusing requirements, the control processing unit 9 controls the focusing module 3 or the motion stage 12 carrying the object under test 10 to scan along a preset direction. The preset direction refers to the direction perpendicular to the optical axis. Specifically, the control unit 9 controls the focusing module 3 or the motion stage 12 carrying the object under test 10 to scan along the direction from the projection position of the target through hole on the plane where the object under test 10 is located to the projection position of the first modulation unit 213 on the plane where the object under test 10 is located, and starts to perform the focusing operation. The first photoelectric signal corresponding to each position point of the focusing module 3 or the motion stage 12 carrying the object under test 10 is acquired by the first detector 6, and the third photoelectric signal corresponding to each position point of the focusing module 3 or the motion stage 12 carrying the object under test 10 is acquired by the second detector 8.

[0108] In one possible implementation, after the focusing operation begins but before acquiring the first and third photoelectric signals corresponding to each position point of the focusing module 3 or the motion stage 12 carrying the object under test 10, the method further includes: Receive the second photoelectric signal and determine the target current value to be set for light source 1 based on the second photoelectric signal; When the target current value is detected to be within the current threshold range of the light source 1, the current value of the power supply is controlled to be the target current value, and the process proceeds to the step of acquiring the first photoelectric signal and the third photoelectric signal corresponding to each position point of the focusing module 3 or the motion stage 12 carrying the object under test 10. If the target current value is detected to exceed the current threshold range of light source 1, the focus enable is stopped from being sent to stop the focus operation; the process returns to receiving the second photoelectric signal and determining the target current value to be set for light source 1 based on the second photoelectric signal.

[0109] It should be noted that the target current value to be set for light source 1 is determined based on the second photoelectric signal, and the target current value to be set for light source 1 is the adjustment current value of light source 1 described above. Please refer to the description above for details.

[0110] After determining the target current value, check whether the target current value is within the current threshold range. , If the target current value is detected within ) Then the current value of the control power supply is If the target current value is detected to be outside the specified range, meaning the required current exceeds the normal operating range of the power supply, it indicates an abnormal reflectivity range has been encountered. Adjusting the power of light source 1 is insufficient to balance the energy received by the second detector 8. Therefore, the focus enable signal is stopped, and the focus-finding function is disconnected. The detection component 7 continues to receive energy until the target current value falls within the current threshold range, at which point the focus-finding function is restored.

[0111] During the focusing process, a second photoelectric signal is also received from the detection component 7. Figure 14 This is a schematic diagram illustrating the correspondence between the projection of a reference modulator onto the plane of the object under test and the object under test during the focusing process, as provided in an embodiment of this application. Figure 14As shown in (a) to (d), the object under test 10 moves in the first direction, first passing through the first through-hole 211, and then through the first modulation unit 213. That is, the detection component 7 can first collect the first reference sub-beam, and then the second detector 8 will collect the first modulated reflected beam. Since the focusing module 3 or the motion stage 12 carrying the object under test 10 scans along the direction from the projection position of the target through-hole on the plane where the object under test 10 is located to the projection position of the first modulation unit 213 on the plane where the object under test 10 is located, the second photoelectric signal obtained by the detection component 7 after passing through the target through-hole is earlier than the third photoelectric signal obtained by the second detector 8 after passing through the first modulation unit 213. That is, the power of the light source 1 is adjusted in advance based on the photoelectric signal collected by the detection component 7 at the previous position, so as to avoid the second detector 8 from saturation or insufficient signal-to-noise ratio during the focusing process at the later position, ensuring that the second detector 8 is in a stable state, improving the accuracy of reflectivity signal detection, thereby improving the accuracy of defocus signal determination, and thus improving focusing accuracy. Figure 2 In the diagram, the positional relationship between the detection component 7 and the second detector 8 is shown. Figure 15 This application provides an embodiment of a detection component, a second detector, and a curve showing the change in the driving current or power of the light source before adjusting the power of the light source. Figure 16 This application provides an embodiment of a detection component, a second detector, and a curve showing the change in the driving current or power of the light source after adjusting the power of the light source. Figure 15 and Figure 16 In the diagram, the horizontal axis represents time t, and the vertical axis represents light intensity or power of light source 1. Curve e represents the change of the signal received by detector component 7 over time, curve f represents the change of the signal received by the second detector 8 over time, and curve g represents the change of the driving current or power of light source 1 over time. Figure 15 As shown, the driving current or power of the light source 1 is constant; the detection component 7 receives the signal Δt earlier than the second detector 8, and the signal collected by the second detector 8 is in a fluctuating state. Figure 16 In this process, the driving current or power of light source 1 is in a state of flux; the detection component 7 receives the signal Δt earlier than the second detector 8, and the signal collected by the second detector 8 is almost in a stable state. That is, by converting the fluctuation value received by the detector into the change in the power of light source 1, the signal received by the second detector 8 is always in a relatively stable state.

[0112] Furthermore, after determining the target current value to be set for the light source 1 based on the second photoelectric signal, it is determined whether the target current value is within the current threshold range. If it exceeds the current threshold range, it indicates that adjusting the current value of the power supply is insufficient to balance the energy received by the second detector 8. Therefore, in this application, when the current threshold range is exceeded, the focus enable is stopped, thereby avoiding the problem of low focus accuracy caused by the low accuracy of the third photoelectric signal collected by the second detector 8.

[0113] S14: Determine the first defocusing amount of the object to be measured based on the first photoelectric signal and the third photoelectric signal corresponding to each position point.

[0114] Before determining the first defocus amount, the motion stage 12 is first used to precisely move the reference surface to be measured along the optical axis at a preset step size. A known standard defocus amount is set for each fixed distance moved. At each standard defocus position, the voltage values ​​of the first and third photoelectric signals at the same position are simultaneously acquired, and the voltage difference between the two signals is calculated. Multiple sets of different standard defocus amounts and their corresponding signal voltage differences are recorded sequentially. A fixed corresponding curve or conversion formula between the two is obtained through data fitting, thus establishing a mapping relationship between the defocus amount and the photoelectric signal difference. Then, from the first and third photoelectric signals obtained in step S13, the first and third photoelectric signals corresponding to the same position point are obtained, and the difference between the first and third photoelectric signals corresponding to the same position point is obtained. Based on the pre-established mapping relationship between the defocus amount and the photoelectric signal difference, the first defocus amount corresponding to each position point can be determined separately.

[0115] S15: Based on the first defocus amount, control the focusing module or the motion stage carrying the object to be tested to move so that the surface of the object to be tested is located at the focal point of the first modulated beam.

[0116] In step S14 above, the first defocus amount corresponding to each position point is determined. In step S15, based on the first defocus amount, controlling the focusing module 3 or the motion stage 12 carrying the object to be tested 10 to move specifically refers to moving along the optical axis. The average of the first defocus amounts of multiple position points is taken to obtain the overall defocus amount of multiple position points.

[0117] In practice, during the process of controlling the movement of the stage 12 carrying the object under test 10 according to the first defocus amount, so that the surface of the object under test 10 is located at the focal position of the first modulated beam, the control processing unit 9 sends a defocus signal containing the overall defocus amount to the motion control module 11, and the motion control module 11 issues a motion control command to the stage 12, so that the stage 12 moves according to the motion control command, so that the surface of the object under test 10 is located at the focal position of the first modulated beam.

[0118] As described above, the focusing module 3 comprises an objective lens 31 and / or a focusing assembly 32. When the focusing assembly 32 is moved along the optical axis according to the first defocus amount, so that the surface of the object under test 10 is located at the focal point of the first modulated beam, the control processing unit 9 generates a focusing drive signal based on the overall defocus amount and sends the focusing drive signal to the focusing assembly 32. The focusing assembly 32 includes a focusing motor 321 and a focusing lens 322. After receiving the drive signal, the focusing motor 321 generates power to drive the focusing lens 322 to move along the optical path, thereby compensating for the focal point shift of the optical path. By adjusting the position of the focusing lens 322, the focal position of the first modulated beam is changed, ultimately allowing the surface of the object under test 10 to accurately fall at the focal point of the first modulated beam.

[0119] When the objective lens 31 is moved along the optical axis according to the first defocus amount, so that the surface of the object under test 10 is located at the focal position of the first modulated beam, the control processing unit 9 generates a focusing drive signal according to the overall defocus amount and sends the focusing drive signal to the drive mechanism connected to the objective lens 31. The drive mechanism receives the focusing drive signal and drives the objective lens 31 to adjust its position along the optical path axis, changing the focal position of the first modulated beam, compensating for the offset caused by the overall defocus, and finally making the surface of the object under test 10 accurately located at the focal position of the first modulated beam.

[0120] The above describes the process of controlling the focusing module 3 or the motion stage 12 carrying the object under test 10 to scan along the direction from the projection position of the target through hole on the plane where the object under test 10 is located to the projection position of the first modulation unit 213 on the plane where the object under test 10 is located, and performing a focusing operation. After controlling the object under test 10 to move along the direction from the projection position of the target through hole on the plane where the object under test 10 is located to the projection position of the first modulation unit 213 on the plane where the object under test 10 is located, the following is also included: If the object under test 10 is detected to have moved outside the projection area of ​​the first modulation unit 213 on the object under test 10, the focus enable signal is stopped, thus stopping the focus operation; the detection component 7 is controlled to clear the collected data. This ensures that the optical focusing device only works within the effective detection area and releases the space occupied by the collected data in the detection component 7, reducing invalid calculations and resource consumption, thereby improving the efficiency and stability of focus control.

[0121] To achieve automated detection, after the control detection component 7 clears the collected data, the following is also included: The scanning of the next line of the target line begins. When scanning the target line, the test object 10 is controlled to move along the projection position of the target through hole on the plane where the test object 10 is located towards the projection position of the first modulation unit 213 on the plane where the test object 10 is located. When the test object 10 is detected to have moved to the projection position of the target through hole of the reference modulator 2 on the plane where the test object 10 is located, the detection element in the detection assembly 7 corresponding to the target through hole is controlled to detect the target reference sub-beam.

[0122] In combination with the above Figure 10 , Figure 11 and Figure 12 If the target is scanned in the first direction, the object under test 10 is controlled to move along the projection position of the first through hole 211 on the plane where the object under test 10 is located towards the projection position of the first modulation unit 213 on the plane where the object under test 10 is located. When the object under test 10 is detected to have moved to the projection position of the first through hole 211 on the plane where the object under test 10 is located, the first detection element 712 in the detection assembly 7 corresponding to the first through hole 211 is controlled to detect the first reference sub-beam, and then the second photoelectric signal is obtained according to the first reference sub-beam to perform the above-mentioned focusing control process. The next row after the target row is scanned in the second direction. The object under test (DUT) 10 is controlled to move along the projection position of the second through-hole 212 on the plane where DUT 10 is located towards the projection position of the first modulation unit 213 on the plane where DUT 10 is located. When it is detected that DUT 10 has moved to the projection position of the second through-hole 212 on the plane where DUT 10 is located, the second detection element 713 in the detection assembly 7 corresponding to the second through-hole 212 is controlled to detect the second reference sub-beam. Then, the second photoelectric signal is obtained based on the second reference sub-beam, and the above-mentioned focusing control process is performed. Other rows are then scanned and focused control is performed sequentially, so that focusing detection can be completed continuously row by row, reducing manual intervention. At the same time, the data is cleared before each row scan to avoid data residue interference, making the detection results of each row more accurate and the overall scanning process more coherent.

[0123] After receiving relevant signals during the focusing control process, such as reflectivity change signal and defocus amount, the control processing unit 9 can transmit these relevant signals to the control unit 16, which then displays and stores the relevant signals.

[0124] The entire process of the focus control method has been described above. In order to enable those skilled in the art to better understand the entire process of the focus control method described above, the following description will continue with reference to the accompanying drawings and embodiments, taking the test object 10 as a wafer. Figure 17 A flowchart of a focusing control method for automatically adapting to changes in wafer reflectivity, as provided in the embodiments of this application, is shown below. Figure 17 As shown, the method includes: S16: Complete the issuance time and coefficient calibration; S17: The motion stage begins focusing, and the focus plane is roughly determined; S18: Turn on the detection component, start collecting data, move a distance d, average the current and send it to the light source controller; S19: Focus tracking is enabled, and the power supply current is changed in real time according to the light source controller. S20: Determine whether the current value is within the current threshold range; if not, return to step S18; if yes, proceed to step S21. S21: Continuous autofocus; S22: Reaching the edge region of the wafer, enabling focus tracking, and clearing the probe component data; S23: Determine whether all rows have been scanned; if yes, proceed to step S24; if no, return to step S18. S24: Scanning complete.

[0125] Combination Figure 5 The entire control process includes: 1. When performing wafer inspection, the control unit 16 sends motion commands to the motion control module 11 and simultaneously sends an adaptive reflectivity change enable; 2. The optical focusing component detects the defocus signal and the reflectivity change signal and feeds them back to the control processing unit 9. The control processing unit 9 transmits the defocus signal to the motion control module 11, so that the motion control module 11 can control the motion stage 12 to perform focus tracking; and synchronously processes the reflectivity signal to transmit the power adjustment signal of the light source 1 to the light source 1 in the optical focusing component. 3. The control transmits the relevant signals to the control unit 16 for processing, display, and storage.

[0126] The entire workflow is explained in detail below: Step 0: Complete the feedback issuance time and coefficient calibration; Step 1: The motion stage 12 activates the focus-finding mode at the designated position to roughly determine the focal plane position; Step 2: The scanning begins. The wafer is outside the field of view of objective lens 31, and no focus tracking is performed. Step 3: The wafer moves to the projection position of the light-transmitting aperture of the reference modulator 2, and the detection component 7 begins to collect data. After moving a distance d, And send the message to the control processing unit 9 to change the current of the light source 1; Step 4: The wafer moves to the projection area of ​​the first modulation section 213, starts the focus tracking mode, receives the signal from the detection component 7 in real time and sends it to the light source 1 controller simultaneously.

[0127] Step 5: Real-time detection If the required current exceeds the normal operating range of light source 1, it indicates an abnormal reflectivity range has been encountered. Adjusting the current of light source 1 is insufficient to balance the energy received by the second detector 8, thus enabling focus and disabling the focus tracking function. Detector component 7 continues to receive energy until the current value meets the requirements, at which point the focus tracking function is restored.

[0128] Step 6: The wafer moves outside the projection area of ​​the first modulation section 213, the tracking is enabled, the data collected by the detection component 7 is cleared, the next row is scanned, and the process is repeated in Step 2 until the wafer scanning is completed.

[0129] The focusing control method provided in this application is applied to the control processing unit 9 in the optical focusing device 100 mentioned above, and has the same or corresponding technical features as the optical focusing device 100 mentioned above, and has the same effect.

[0130] The above-described preferred embodiments have further detailed the purpose, technical solutions, and advantages of this application. It should be understood that the above description is only a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A reference modulator applied to an optical focusing device, the optical focusing device comprising a light source and a detection component, the light source being used to generate illumination light, the optical focusing device being used to focus on an object under test, the object under test being movable along a first direction and a second direction opposite to the first direction, characterized in that, The reference modulator includes: A first substrate, wherein the first substrate has a first through hole and a second through hole; A first modulation unit is disposed on the first substrate, and the first through hole and the second through hole are located on both sides of the first modulation unit; The first modulation unit is used to modulate the illumination light to form a first modulation beam, and the first modulation beam is used to focus the object under test. The first through hole is used to allow the illumination light to pass through to form a first reference beam. The first reference beam is used to illuminate the detection area in advance before focusing the detection area of ​​the test object using the first modulated beam during the movement of the test object along the first direction, so as to obtain the first surface reflectivity of the detection area through the detection component, and then dynamically adjust the working parameters of the light source according to the first surface reflectivity. The second through-hole is used to allow the illumination light to pass through, so as to form a second reference beam. The second reference beam is used to illuminate the detection area in advance during the movement of the test object along the second direction, before focusing the detection area of ​​the test object using the first modulated beam, so as to obtain the second surface reflectivity of the detection area through the detection component, and then dynamically adjust the operating parameters of the light source according to the second surface reflectivity.

2. The reference modulator according to claim 1, characterized in that, The first substrate has a third through hole, and the first modulation part is fixedly installed in the third through hole.

3. The reference modulator according to claim 1, characterized in that, The first substrate is a transparent substrate, and the first modulation part is fixedly mounted on the surface of the first substrate.

4. The reference modulator according to any one of claims 1 to 3, characterized in that, The first through hole and the second through hole are symmetrically disposed on both sides of the first modulation section.

5. A complementary modulator, characterized in that, Used in conjunction with the reference modulator as described in any one of claims 1 to 4, comprising: The second substrate has a first blocking part and a second blocking part. The first blocking part is positioned corresponding to the first through hole and is used to block the first reference sub-beam generated after the first reference beam is incident on the test object from passing through. The second blocking part is positioned corresponding to the second through hole and is used to block the second reference sub-beam generated after the second reference beam is incident on the test object from passing through. The second modulation unit is disposed on the second substrate and is offset from the first modulation unit on the pupil surface or conjugate surface. It is used to modulate the first modulation reflection beam generated after the first modulation beam is incident on the test object to form a second modulation reflection beam.

6. A detection component, characterized in that, Used in conjunction with the reference modulator as described in any one of claims 1 to 4, comprising: The mounting plate has a fifth through hole for the first modulated reflected beam generated after the first modulated beam is incident on the object under test to pass through. A first detection element is disposed on the mounting plate, and the position of the first detection element corresponds to the position of the first through hole, for receiving the first reference sub-beam generated after the first reference beam is incident on the object under test. The second detection element is disposed on the mounting plate and corresponds to the position of the second through hole. It is used to receive the second reference sub-beam generated after the second reference beam is incident on the object under test.

7. An optical focusing device, characterized in that, include: A light source, used to provide illumination; The reference modulator as described in any one of claims 1 to 4 is disposed in the transmission optical path of the illumination light and is used to form a first reference beam, a second reference beam, and a first modulated beam; A focusing module is disposed in the post-stage optical path of the reference modulator, and is used to project a first reference beam, a second reference beam and a first modulation beam onto the surface of the object under test, and to collect a first reference sub-beam, a second reference sub-beam and a first modulation reflection beam generated on the surface of the object under test, wherein the first reference sub-beam corresponds to the first reference beam, the second reference sub-beam corresponds to the second reference beam, and the first modulation reflection beam corresponds to the first modulation beam. A beam splitting module is disposed in the post-stage optical path of the focusing module, and is used to split the first reference sub-beam, the second reference sub-beam and the first modulated reflection beam into a first detection optical path and a second detection optical path. A complementary modulator, disposed in the first detection optical path, is used to modulate the first modulated reflected beam corresponding to each position point during the scanning process of the focusing module or the motion stage carrying the test object along a preset direction, so as to form a second modulated reflected beam. The complementary modulator is used in conjunction with the reference modulator. The complementary modulator includes: a second substrate, the second substrate having a first blocking part and a second blocking part, the first blocking part corresponding to the position of the first through hole, used to block the first reference sub-beam generated after the first reference beam is incident on the test object from passing through, the second blocking part corresponding to the position of the second through hole, used to block the second reference sub-beam generated after the second reference beam is incident on the test object from passing through; a second modulation part, the second modulation part being disposed on the second substrate, the second modulation part being offset from the first modulation part on the pupil surface or conjugate surface, used to modulate the first modulated reflected beam generated after the first modulated beam is incident on the test object, so as to form a second modulated reflected beam. A first detector is disposed in the optical path of the complementary modulator to detect the second modulated reflected beam and obtain multiple first photoelectric signals. A detection component, disposed in the second detection optical path, is used to detect the first reference sub-beam or the second reference sub-beam to obtain a second photoelectric signal. The detection component works in conjunction with the reference modulator. The detection component includes: a mounting plate having a fifth through hole for allowing the first modulated reflected beam generated after the first modulated beam is incident on the test object to pass through; a first detection element disposed on the mounting plate, corresponding to the position of the first through hole, for receiving the first reference sub-beam generated after the first reference beam is incident on the test object; and a second detection element disposed on the mounting plate, corresponding to the position of the second through hole, for receiving the second reference sub-beam generated after the second reference beam is incident on the test object. The second detector is disposed in the second detection optical path and is used to detect the first modulated reflected beam corresponding to each position point of the focusing module or the motion stage carrying the object under test during the scanning process along the preset direction, so as to obtain multiple third photoelectric signals. The control processing unit is connected to the light source, the first detector, the detection component, the second detector, and the focusing module. The control processing unit is used for: Based on the second photoelectric signal, determine whether the output power of the light source meets the focusing requirements; If the output power of the light source does not meet the focusing requirements, control the light source to adjust its output power. After the output power of the light source meets the focusing requirements, the focusing module or the motion stage carrying the object under test is controlled to scan along a preset direction to obtain the first photoelectric signal and the third photoelectric signal corresponding to each position point of the focusing module or the motion stage carrying the object under test. The first defocusing amount of the object under test is determined based on the first photoelectric signal and the third photoelectric signal corresponding to each location point; Based on the first defocusing amount, the focusing module or the motion stage carrying the object under test is controlled to move so that the surface of the object under test is located at the focal point of the first modulated beam.

8. The optical focusing device according to claim 7, characterized in that, The second detector is disposed in the subsequent optical path of the detection component.

9. The optical focusing device according to claim 7 or 8, characterized in that, The reference modulator is conjugate with the surface of the object under test.

10. The optical focusing device according to claim 7, characterized in that, The conjugate surface of the reference modulator is conjugate with that of the complementary modulator.

11. The optical focusing device according to claim 7, characterized in that, The photosensitive surface of the detection component is conjugate with the conjugate surface of the reference modulator.

12. The optical focusing device according to claim 7, characterized in that, The focusing module is an objective lens or a focusing assembly, and the objective lens or the focusing assembly is located in the optical path between the reference modulator and the object under test. The focusing module comprises the focusing assembly and the objective lens, which are sequentially arranged in the optical path between the reference modulator and the object under test.

13. A semiconductor device, characterized in that, include: The optical focusing device as described in any one of claims 7 to 12.

14. A focusing control method, applied to the optical focusing device as described in any one of claims 7 to 12, characterized in that, include: Acquire the second photoelectric signal; Based on the second photoelectric signal, determine whether the output power of the light source meets the focusing requirements; If the output power of the light source does not meet the focusing requirements, control the light source to adjust its output power. After the output power of the light source meets the focusing requirements, the focusing module or the motion stage carrying the object under test is controlled to scan along a preset direction to obtain the first photoelectric signal and the third photoelectric signal corresponding to each position point of the focusing module or the motion stage carrying the object under test. The first defocusing amount of the object under test is determined based on the first photoelectric signal and the third photoelectric signal corresponding to each location point; Based on the first defocusing amount, the focusing module or the motion stage carrying the object under test is controlled to move so that the surface of the object under test is located at the focal point of the first modulated beam.

15. The focusing control method according to claim 14, characterized in that, After the initial focusing of the object under test and before acquiring the second photoelectric signal, the method further includes: Once the scanning starts, the relationship between the object under test and the field of view of the objective lens in the focusing module is obtained. If the object to be tested is detected to be outside the objective lens's field of view, focusing will not be performed. During target row scanning, the test object is controlled to move along the projection position of the target through-hole on the plane of the test object toward the projection position of the first modulation unit on the plane of the test object. When the test object is detected to have moved to the projection position of the target through-hole of the reference modulator on the plane of the test object, the detection element in the detection assembly corresponding to the target through-hole is controlled to detect the target reference sub-beam, and the step of acquiring the second photoelectric signal is entered. In this step, when scanning adjacent rows of the target row, the movement direction of the test object is opposite, the target through-hole is the first through-hole or the second through-hole, and the target reference sub-beam is the first reference sub-beam or the second reference sub-beam.

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