Scanning focusing device, focusing system, semiconductor apparatus, and method

Abstract

The application discloses a scanning focusing device, a focusing system, a semiconductor device and a method. The device comprises an interference scanning module, the interference scanning module comprising a measuring objective lens, a reference objective lens and a reference mirror. The measuring objective lens is arranged in a measuring light path and is used for projecting measuring light to a target sample surface and receiving measuring signal light returned after being reflected by the target sample. The reference objective lens is arranged in a reference light path and is used for focusing reference light to the reference mirror and receiving reference signal light returned after being reflected by the reference mirror. The reference light path is parallel to the measuring light path. The reference mirror is arranged at the end of the reference light path and is used for reflecting the reference light back to the reference objective lens. A first adjusting mechanism is used for driving the interference scanning module to scan along the measuring light path and for driving the interference scanning module to move to a target focusing position. The device is beneficial to improving the focusing speed of a semiconductor manufacturing device.

Description

Technical Field

[0001] This application relates to the field of optical components and systems, and in particular to a scanning focusing device, focusing system, semiconductor device and method. Background Technology

[0002] As semiconductor manufacturing processes advance to smaller nodes, high-precision focusing technology plays a crucial role in optical measurement and inspection equipment. Especially in key process steps such as image-based overlay (IBO) error measurement, optical systems are required to achieve fast and stable autofocus in dynamic environments to ensure image clarity and measurement repeatability.

[0003] Interferometric focusing devices are widely used in focusing systems for semiconductor equipment. An interferometric focusing device uses a beam splitter to divide the light source into reference light and measurement light. These are reflected by the reference objective-reference mirror and the measurement objective-sample surface, respectively, and then re-merge to generate an interference signal. When the optical path difference between the two beams approaches zero, the contrast of the interference fringes reaches its maximum, thus enabling precise focusing on the sample surface.

[0004] In interferometric focusing devices, to ensure that the sample surface is located on the focal plane of the measurement objective, the following two conditions must typically be met: (1) the optical path from the beam splitter to the reference objective and the measurement objective are equal; and (2) the reference mirror is located on the focal plane of the reference objective. To maintain the above optical path consistency and focal plane matching, in the prior art, it is necessary to synchronously move the light source, illumination module, beam splitter, the entire reference optical path assembly, and the measurement optical path assembly to generate a varying optical path difference, thereby achieving focusing under interference conditions. However, this full-optical-path linkage adjustment method has many moving parts and a large overall motion mass, which increases the load on the focusing mechanism, thereby limiting the focusing speed and reducing the working efficiency of semiconductor manufacturing equipment. Summary of the Invention

[0005] This application discloses a scanning focusing device, focusing system, equipment and method for improving the focusing speed of semiconductor manufacturing equipment, thereby solving the technical problem of low working efficiency of semiconductor manufacturing equipment.

[0006] In a first aspect, this application provides a scanning focusing device applied to an optical focusing system. The optical focusing system includes a light source, an interference beam splitting module, and an interference signal collection module. The interference beam splitting module is disposed on the light-emitting side of the light source and is used to split the illumination light provided by the light source to obtain measurement light and reference light. The device includes: an interference scanning module and a first adjustment mechanism, the first adjustment mechanism being connected to the interference scanning module; the interference scanning module includes a measurement objective lens, a reference objective lens, and a reference reflector, wherein: the measurement objective lens is disposed in the measurement optical path and is used to project the measurement light onto the surface of the target sample and receive the measurement signal reflected back by the target sample. The light source includes a reference objective lens positioned in the reference optical path to focus the reference light onto the reference mirror and receive the reference signal light reflected back by the reference mirror. The reference optical path is parallel to the measurement optical path. The reference mirror is positioned at the end of the reference optical path to reflect the reference light back to the reference objective lens. A first adjustment mechanism is used to drive the interferometric scanning module to scan along the measurement optical path and to drive the interferometric scanning module to move to the target focusing position. The target focusing position is determined by the interferometric signal collection module acquiring the interference signal generated by the change in optical path difference between the measurement signal light and the reference signal light during the scanning process of the interferometric scanning module along the measurement optical path.

[0007] As can be seen, by setting the reference optical path and the measurement optical path as parallel structures and integrating the measurement objective, reference objective, and reference reflector into the interferometric scanning module, the first adjustment mechanism only needs to drive the interferometric scanning module to scan and focus along the optical path direction during focusing and scanning. It does not need to drive other components such as the light source and the interferometric beam splitting module at the same time. This effectively reduces the overall mass of the components that the first adjustment mechanism needs to drive, reduces the scanning load, increases the scanning speed, shortens the focusing time, and thus improves the working efficiency of the semiconductor equipment.

[0008] In conjunction with the first aspect, in one possible implementation, the scanning focusing device further includes: a second adjustment mechanism connected to a reference objective lens, the second adjustment mechanism being used to adjust the pose of the reference objective lens; or, the second adjustment mechanism connected to a reference mirror, the second adjustment mechanism being used to adjust the pose of the reference mirror; or, the second adjustment mechanism being connected to both the reference objective lens and the reference mirror, the second adjustment mechanism being used to simultaneously adjust the poses of the reference objective lens and the reference mirror.

[0009] It can be seen that by introducing a second adjustment mechanism connected to the reference objective and / or reference mirror in the scanning focusing device, high-precision adjustment and calibration of the reference optical path can be achieved, keeping the reference optical path parallel to the measurement optical path, thereby ensuring the accuracy and stability of focusing.

[0010] In conjunction with the first aspect, in one possible implementation, the second adjustment mechanism is connected to both the reference objective and the reference mirror, and the scanning focusing device further includes a lens barrel in which the reference objective and the reference mirror are mounted, and the second adjustment mechanism is connected to the lens barrel.

[0011] As can be seen, by integrating the reference objective and reference mirror into the lens barrel and adjusting the overall position of the lens barrel by the second adjustment mechanism, this scanning focusing device achieves precise optical path calibration while further reducing the scanning load and improving the focusing speed.

[0012] In conjunction with the first aspect, in one possible implementation, the measuring objective and the reference objective share the same objective type and have the same numerical aperture.

[0013] It can be seen that by selecting the same type and configuring the same numerical aperture for the measurement objective and the reference objective, the scanning focusing device can achieve good symmetry between the measurement optical path and the reference optical path at the optical path level, thus improving the quality of the interference signal, enhancing the stability of the focusing process and the accuracy of the focus position determination.

[0014] Secondly, this application also provides an optical focusing system, including some or all of the scanning focusing devices as described in the first aspect; an interference beam splitting module, an interference signal collection module, a processor, and a controller, wherein the interference signal collection module is connected to the controller, and the controller is connected to a first adjustment mechanism, wherein: the interference beam splitting module is disposed on the light-emitting side of the light source and is used to split the externally provided illumination light to obtain a measurement light and a reference light; the interference signal collection module is disposed in the converging optical path and is used to collect the measurement signal light formed after the measurement light is reflected by the target sample and the reference signal light formed after the reference light is reflected by the target sample, wherein the converging optical path is the path through which the measurement signal light and the reference signal light converge; the processor is used to determine the target focusing position of the interference scanning module by the interference signal generated by the change of the optical path difference between the measurement signal light and the reference signal light; and the controller is used to control the first adjustment mechanism to drive the interference scanning module to move to the target focusing position.

[0015] As can be seen, the optical focusing system generates parallel measurement and reference beams through an interference beam splitting module, then uses an interference signal collection module to acquire the interference signal of the two beams. The control processing unit then calculates the target focus position based on the interference signal and controls the interference scanning module to quickly achieve focus based on this position. Because the interference scanning module moves independently of other optical components, the optical focusing system effectively reduces motion load and improves focus response speed while achieving high-precision focusing and positioning.

[0016] In conjunction with the second aspect, in one possible implementation, the interference beam splitting module includes: a first beam splitter and a first refracting mirror, wherein: the first beam splitter is disposed on the light-emitting side of the light source, and is used to split the illumination light to obtain a measurement light and a reference light, and transmit the measurement light to the measurement objective lens, and transmit the reference light to the refracting mirror; the first refracting mirror is disposed in the reference optical path, and is used to deflect the reference light so that the deflected reference optical path is parallel to the measurement optical path, and transmit the refracted reference light to the reference objective lens.

[0017] As can be seen, the interference beam splitting module completes the beam splitting of the illumination light through the first beam splitter, and then uses the first refracting mirror to fold the direction of the reference optical path, so that the reference optical path and the measurement optical path remain parallel in space; thus realizing a parallel optical path structure, when the scanning and focusing device moves in a single direction, it can simultaneously change the effective optical path length of the reference optical path and the measurement optical path in that direction, realizing continuous adjustment of the optical path difference between the two optical paths. In addition, by concentrating the optical path folding function in the interference beam splitting module, the scanning and focusing device does not need to integrate the interference beam splitting module, which significantly reduces the weight of the interference scanning module, which is conducive to improving the speed and stability of the interference scanning module, and further improves the working efficiency of the semiconductor equipment.

[0018] In conjunction with the second aspect, in one possible implementation, the system further includes: a third adjustment mechanism connected to the first refracting mirror; the third adjustment mechanism is used to adjust the pose of the first refracting mirror so that the reference optical path is parallel to the measurement optical path.

[0019] It can be seen that by setting a third adjustment mechanism connected to the first refracting mirror, the direction of the reference optical path can be independently and precisely adjusted, achieving parallelism calibration between the reference and measurement optical paths without changing the state of the measurement optical path. This independent adjustment method avoids adding additional adjustment structures to the scanning and focusing device, thus maintaining the lightweight design of the interferometric scanning module while ensuring optical path accuracy, which is beneficial for improving scanning speed and focusing efficiency.

[0020] In conjunction with the second aspect, in one possible implementation, the interference signal collection module includes: a first relay lens group and a focusing sensor; the first relay lens group is disposed in front of the focusing sensor and is used to converge the measurement signal light and the reference signal light to the focusing sensor; the focusing sensor is used to receive the measurement signal light and the reference signal light.

[0021] As can be seen, by focusing the interference beam onto the focusing sensor through the first relay mirror group, this interference signal collection module can efficiently collect the interference signal generated by the measurement signal light and the reference signal light, and convert the optical signal into an electrical signal for processor analysis. While ensuring signal collection efficiency, it provides a reliable data foundation for subsequent interference signal processing and target focusing position determination.

[0022] In conjunction with the second aspect, in one possible implementation, the interference beam splitting module further includes: a variable aperture; the variable aperture is disposed in the reference optical path and is used to open or close the reference optical path.

[0023] As can be seen, by setting a variable aperture in the reference optical path, the interference beam splitting module can flexibly control the on / off state of the reference optical path in different working modes. When focusing, the reference optical path is turned on to ensure the normal generation of the interference signal, and when measuring, the reference optical path is turned off to avoid the interference of the reference light on the measurement signal. This selective on / off control enables the system to quickly switch between the focusing mode and the measurement mode, thus improving the signal-to-noise ratio of the measurement signal while ensuring focusing accuracy.

[0024] In conjunction with the second aspect, in one possible implementation, the optical focusing system further includes: an illumination modulation module; the illumination modulation module is disposed between the light source and the interference beam splitting module, and is used to modulate the illumination light.

[0025] As can be seen, by setting an illumination modulation module between the light source and the interferometric beam splitter, this optical focusing system can flexibly adjust the illumination light to adapt to different measurement conditions. Since the illumination modulation module is arranged independently of the interferometric scanning module and does not move with the scanning motion, the illumination modulation state remains stable during rapid focusing scanning, avoiding changes in the illumination mode caused by scanning motion, thereby ensuring the stability of the measurement performance.

[0026] In conjunction with the second aspect, in one possible implementation, the optical focusing system further includes: a second relay lens group and a collection and detection module; the second relay lens group is disposed on the light-incident side of the collection and detection module, and is used to transmit the measurement signal light and the reference signal light to the interferometric signal collection module before the interferometric scanning module moves to the target focusing position; and to transmit the measurement signal light to the collection and detection module after the interferometric scanning module moves to the target focusing position; the collection and detection module is disposed at the end of the measurement optical path, and is used to collect the measurement signal light and generate measurement data of the target sample based on the measurement signal light.

[0027] As can be seen, by setting up a fourth relay mirror group and a collection detector, the interference beam is transmitted to the interference signal collection module via the second relay mirror group in focusing mode, and the measurement signal light is transmitted to the collection detector via the fourth relay mirror group in measurement mode, thus avoiding optical path conflicts and signal interference between the two modes. This optical path design simplifies the system structure while ensuring that focusing and measurement functions are implemented independently, providing reliable optical architecture support for the efficient operation of the system.

[0028] Thirdly, this application also provides a semiconductor device, including part or all of the optical focusing system as described in the second aspect.

[0029] As can be seen, this semiconductor device achieves precise focusing by integrating an optical focusing system and utilizing the principle of interference. A first adjustment mechanism drives the independent movement of the interferometric scanning module to complete rapid focusing. Because the interferometric scanning module has a light motion load and a high scanning speed, the overall focusing time of the device is significantly shortened, thereby improving the overall yield of the semiconductor metrology process. Simultaneously, components such as the illumination modulation module and the interferometric beam splitting module in the optical focusing system do not move with the scanning, ensuring the stability of the illumination mode and the repeatability of the measurement performance. This structural design gives the semiconductor device significant performance advantages in high-precision, high-speed metrology applications, better meeting the dual demands of modern semiconductor manufacturing for both yield and accuracy.

[0030] Fourthly, this application also provides a focusing control method applied to an optical focusing system as described in the second aspect. The method includes: controlling a first adjustment mechanism to drive an interferometric scanning module to scan along a measurement optical path; during the scanning process, acquiring an interference signal generated by a measurement signal light and a reference signal light; determining the target focusing position of the interferometric scanning module based on the interference signal; and controlling the first adjustment mechanism to drive the interferometric scanning module to move to the target focusing position.

[0031] As can be seen, this focusing control method drives the interferometric scanning module to scan along the optical path, collects interference signals, analyzes and determines the target focusing position, and finally drives the module to move to that position, thus realizing closed-loop focusing control based on the interference principle. Because the interferometric scanning module has a light motion load and a fast scanning speed, the entire focusing process can be completed in a short time, significantly improving the response speed and overall efficiency of the optical focusing system.

[0032] In conjunction with the fourth aspect, in one possible implementation, after controlling the first adjustment mechanism to drive the interferometric scanning module to the target focusing position, the method further includes: closing the variable aperture disposed in the reference optical path.

[0033] As can be seen, in this embodiment of the application, by closing the variable aperture in the reference optical path after focusing, the interference of the reference light on the subsequent measurement signal is effectively avoided. Therefore, it not only ensures the normal generation of interference signals during focusing, but also ensures the high signal-to-noise ratio of the signal during measurement, thereby improving the stability of the overall measurement performance.

[0034] In conjunction with the fourth aspect, in one possible implementation, after controlling the first adjustment mechanism to drive the interferometric scanning module to the target focusing position, the method further includes locking the first adjustment mechanism.

[0035] As can be seen in this embodiment, locking the first adjustment mechanism after focusing can effectively avoid the position drift of the interference scanning module caused by external vibration or movement of the stage, thus ensuring that the relative position between the objective lens and the sample remains stable during subsequent measurement, thereby ensuring the accuracy of the measurement data.

[0036] In conjunction with the fourth aspect, in one possible implementation, before controlling the first adjustment mechanism to drive the interferometric scanning module to scan along the measurement optical path, the method further includes: controlling the motion stage carrying the target sample to move to the first measurement position, so that the measurement objective lens measures the first measurement point of the target sample, the first measurement position being located in the measurement plane, and the measurement plane being perpendicular to the measurement optical path.

[0037] As can be seen, by controlling the motion stage to move to the first measurement position before scanning and focusing, this focusing control method achieves pre-alignment of the measurement point with the measurement optical path, providing support for the efficient operation of the overall measurement process.

[0038] In conjunction with the fourth aspect, in one possible implementation, after controlling the first adjustment mechanism to drive the interferometric scanning module to move to the target focusing position, the method further includes: controlling the motion stage carrying the target sample to move to the second measurement position, so that the second measurement point of the target sample is measured, the second measurement position being located in the measurement plane; controlling the first adjustment mechanism to drive the interferometric scanning module to scan along the measurement optical path again.

[0039] As can be seen from the embodiments of this application, by controlling the motion stage to move sequentially to different measurement positions and repeatedly performing focusing scans, this method realizes continuous focusing operations on multiple measurement points on the target sample, providing efficient focusing support for multi-point measurement.

[0040] In conjunction with the fourth aspect, in one possible implementation, before controlling the first adjustment mechanism to drive the interferometric scanning module to scan along the measurement optical path, the method further includes: controlling the third adjustment mechanism to adjust the orientation of the refracting mirror so that the reference optical path is parallel to the measurement optical path.

[0041] As can be seen in this embodiment, because the attitude of the first refracting mirror is calibrated before scanning and focusing, it is possible to ensure that the reference optical path and the measurement optical path remain parallel, thus ensuring the quality of the interference signal and the accuracy of the focus position determination.

[0042] In conjunction with the fourth aspect, in one possible implementation, before controlling the first adjustment mechanism to drive the interferometric scanning module to scan along the measurement optical path, the method further includes: controlling the second adjustment mechanism to adjust the reference objective and / or reference reflector so that the reference optical path is parallel to the measurement optical path.

[0043] As can be seen in the embodiments of this application, because the pose calibration of the reference objective or reference mirror is performed before scanning and focusing, it can be ensured that the reference optical path and the measurement optical path remain strictly parallel, thus ensuring the quality of the interference signal and the accuracy of the focus position determination.

[0044] In conjunction with the fourth aspect, in one possible implementation, before determining the target focus position of the interferometric scanning module based on the interferometric signal, the method further includes: determining the signal-to-noise ratio of the interferometric signal; if the signal-to-noise ratio of the interferometric signal is lower than a preset threshold, then performing the following operations: increasing the brightness of the light source; controlling the first adjustment mechanism again to drive the interferometric scanning module to scan along the measurement optical path; and during the scanning process, re-acquiring the interference signal generated by the measurement signal light and the reference signal light.

[0045] As can be seen in the embodiments of this application, by introducing a signal-to-noise ratio judgment and adaptive adjustment mechanism before determining the target focus position, the focus control method can effectively cope with signal quality fluctuations caused by factors such as sample reflectivity differences and environmental interference, thus ensuring that the interference signal used for focus position calculation has a sufficient signal-to-noise ratio, thereby improving the reliability and accuracy of focusing. Attached Figure Description

[0046] 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 the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0047] Figure 1 This is a schematic diagram of the focusing posture of an interference scanning module in an existing semiconductor device. Figure 2 This is a schematic diagram of the structure of a semiconductor device provided in an embodiment of this application; Figure 3 This is a schematic diagram of the structure of an optical focusing system provided in an embodiment of this application; Figure 4 This is a schematic diagram of the structure of a control processing unit provided in an embodiment of this application; Figure 5 This is a schematic diagram of the structure of an interference beam splitting module provided in an embodiment of this application; Figure 6 A schematic diagram of the adjustment dimension of a third adjustment mechanism provided in an embodiment of this application; Figure 7 This is a schematic diagram of the structure of the interference signal collection module provided in the embodiments of this application; Figure 8This is a schematic diagram of another interference beam splitting module provided in an embodiment of this application; Figure 9 This is a schematic diagram of the structure of a light source and illumination modulation module provided in an embodiment of this application; Figure 10 A schematic diagram of the structure of a second relay mirror group and a collection and detection module provided in this application embodiment; Figure 11 This is a schematic diagram of the structure of a collection and detection module provided in an embodiment of this application; Figure 12 This is a schematic diagram of the structure of a scanning focusing device provided in an embodiment of this application; Figure 13 This is a schematic diagram of the interference signal generated by the change of the measurement signal light and the reference signal light as the scanning position changes, provided in an embodiment of this application. Figure 14A This is a schematic diagram of another scanning and focusing device provided in an embodiment of this application; Figure 14B A schematic diagram of the adjustment dimension of a second adjustment mechanism provided in an embodiment of this application; Figure 15 This is a schematic diagram of another scanning and focusing device provided in an embodiment of the present application; Figure 16 A schematic flowchart of a focusing control method provided in an embodiment of this application; Figure 17 This is a data flow diagram of a focus control method provided in an embodiment of this application.

[0048] Explanation of reference numerals in the attached figures: 10 - Semiconductor scanning equipment; 101-Scanning and focusing module; 102-Scanning signal collection module; 103-Control unit; 1011 - Scanning light source; 1012 - Scanning beam splitter; 1013 - Scanning objective lens; 1014 - Scanning reference objective lens; 1015 - Scanning reference mirror; 1021 - Scanning sensor; 1022 - Scanning repeater mirror; 20 - Semiconductor equipment; 201 - Optical focusing system; 202 - Motion stage; 2011 - Scanning and focusing device; 2012 - Light source; 2013 - Interference beam splitting module; 2014 - Interference signal collection module; 2015 - Control and processing unit; 2016 - Third adjustment mechanism; 2017 - Illumination modulation module; 2018 - Third relay mirror group; 2019 - Second relay mirror group; 20110 - Collection and detection module; 20111 - Interference scanning module; 20112 - First adjustment mechanism; 20113 - Second adjustment mechanism; 201111 - Measuring objective; 201112 - Reference objective; 201113 - Reference mirror; 201114 - Lens tube; 20131 - First beam splitter; 20132 - First refracting mirror; 20133 - Variable aperture; 20141 - First relay lens group; 20142 - Focusing sensor; 20151 - Processor; 20152 - Controller; 20153 - Processing Module; 20154 - Analysis Module; 20155 - Control Module; 201101 - Fourth relay mirror group; 201102 - Collection detector. Detailed Implementation

[0049] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0050] The terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.

[0051] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0052] The scanning focusing device, focusing system, equipment and methods involved in this solution are mainly used in high-end semiconductor equipment with stringent requirements for focusing accuracy and speed, such as overlay equipment, bright field inspection equipment, dark field inspection equipment, photolithography equipment, etc.

[0053] The scanning focusing device, focusing system, equipment and method involved in this solution are applied to semiconductor measurement and manufacturing scenarios such as image-based measurement equipment or diffraction-based overlay error measurement equipment. In the above scenarios, it is necessary to perform fault identification, image generation and other operations on the target sample (such as mask or wafer) and output the obtained fault data or image data.

[0054] In order to achieve the above-mentioned fault identification, image generation and other steps, the focusing accuracy and speed of the objective lens and the sample directly affect the accuracy of the final measurement results and the overall productivity of the equipment.

[0055] The following describes the prior art involved in the embodiments of this application.

[0056] Semiconductor equipment, such as image-based overlay (IBO) or diffraction-based overlay (DBO) equipment, is a key quality control device in semiconductor manufacturing processes. This type of equipment typically includes a stage for carrying and moving the target sample, an optical focusing system for achieving precise focusing (including a light source, illumination module, reference objective, reference mirror, measurement objective, and focus sensor), and a collection and detection module (including a collection detector) for collecting measurement signals. The performance and speed of the optical focusing system directly affect the overall measurement accuracy and efficiency of the equipment.

[0057] Optical focusing systems are the core modules for achieving precise positioning of target sample surfaces. The scanning focusing device within these systems is typically based on the principle of interference, determining the optimal focal plane position by generating and analyzing interference signals. A common type of scanning focusing device is the interferometric scanning focusing device, which includes an interferometric scanning module consisting of a measuring objective lens, a reference objective lens, and a reference mirror, as well as a scanning mechanism (not shown in the figure) for driving its movement.

[0058] The interferometric scanning module further includes a measurement objective, a reference objective, and a reference reflector. Its working principle is as follows: the measurement light is focused onto the target sample surface by the measurement objective and reflected back as measurement signal light; the reference light is focused onto the reference reflector by the reference objective and reflected back as reference signal light. The scanning mechanism changes the optical path difference between the measurement and reference optical paths. The two reflected beams merge to generate an interference signal. By analyzing this interference signal, the focusing position on the sample surface can be accurately located.

[0059] However, existing interferometric focusing devices have significant shortcomings in practical applications. (See also...) Figure 1 , Figure 1 This is a schematic diagram of the focusing posture of an interference scanning module in an existing semiconductor device.

[0060] The semiconductor scanning device 10 shown in the figure includes a scanning focusing module 101, a scanning signal collection module 102, and a control unit 103. The scanning focusing module 101 is used to scan the target sample and obtain the scanning signal of the target sample based on the control of the control unit 103. The scanning signal collection module 102 is used to collect the scanning signal. The control unit 103 is used to receive the scanning signal and convert the scanning signal into a scanning image.

[0061] Furthermore, the scanning focusing module 101 includes a scanning light source 1011; a scanning beam splitter 1012; a scanning objective lens 1013; a scanning reference objective lens 1014; and a scanning reference mirror 1015. The scanning light source 1011 generates primary illumination light and transmits it to the scanning beam splitter 1012. The scanning beam splitter 1012 is configured in the primary illumination light path and generates scanning illumination light and scanning reference light based on the primary illumination light, and then transmits the scanning illumination light and scanning reference light to the scanning objective lens 1013 and the scanning reference objective lens 1014.

[0062] The scanning objective lens 1013 is disposed in the scanning illumination optical path and is used to scan the target sample based on the control light of the control unit 103.

[0063] The scanning reference objective 1014 is disposed in the scanning illumination optical path and is used to transmit the scanning reference light to the scanning reference mirror 1015. The scanning reference mirror 1015 is disposed at the position that is focused on the scanning reference objective 1014.

[0064] The scanning signal collection module 102 includes a scanning relay mirror 1022 and a scanning sensor 1021 arranged in sequence. The scanning relay mirror 1022 is used to converge the light signal obtained from scanning the target sample to the scanning signal collection module 102. The scanning signal collection module 102 is used to convert the light signal transmitted by the scanning relay mirror 1022 into a digital or electrical signal and send it to the control unit 103 to achieve focusing or scanning.

[0065] like Figure 1 The focusing process of the semiconductor scanning device 10 shown specifically includes: Under the premise that the optical path length of the scanning measurement light reaching the output end of the scanning objective 1013 and the optical path length of the scanning reference light reaching the output end of the scanning reference objective 1014 are equal (Zm=Zr), the scanning objective 1013 performs a Z-axis scan along the optical axis based on the control command of the control unit 103 to generate an optical path difference sequence. Then, the scanning signal collection module 102 receives the scanning signal generated in this process and sends it to the control unit 103. The control unit 103 finds the focal position between the scanning objective 1013 and the target sample based on the scanning signal. At this position, the distance from the target sample to the scanning objective 1013 (i.e., Fm) is equal to the distance from the scanning reference objective 1014 to the scanning reference mirror 1015 (i.e., Fr) (i.e., Fm=Fr). Then, based on this focal position, the scanning objective 1013 can be further adjusted to achieve focusing of the measurement sample and the scanning objective 1013.

[0066] Furthermore, it should be noted that if one attempts to move only the scanning objective lens 1013 to change the relative position of the scanning objective lens 1013 and the target sample so that Fm=Fr, Zm+Fm will remain unchanged, and thus the position where Zm=Zr and Fm=Fr can never be found, thus failing to achieve the focusing problem.

[0067] Therefore, the existing focusing scheme treats the entire scanning and focusing module 101, which includes a scanning light source 1011, a scanning beam splitter 1012, a scanning objective lens 1013, a scanning reference objective lens 1014, and a scanning reference mirror 1015, as a whole, and drives it to perform Z-axis scanning by a moving mechanism (not shown in the figure). However, in this scheme, the scanning load of the moving mechanism is too large, making it difficult to achieve high-speed movement, and the scanning and focusing speeds are relatively low, ultimately leading to the technical problem of low operating efficiency of semiconductor manufacturing equipment.

[0068] Example 1 To address the aforementioned problems, this application provides a semiconductor device 20. Please refer to [link / reference]. Figure 2 and Figure 3 , Figure 2 This is a schematic diagram of the structure of a semiconductor device 20 provided in an embodiment of this application. Figure 3 This is a schematic diagram of an optical focusing system 201 provided in an embodiment of this application. The semiconductor device 20 includes an optical focusing system 201 and a motion stage 202. The optical focusing system 201 is used to ensure that the target sample is always at the optimal focal plane through high-precision automatic focusing. The optical focusing system 201 and the motion stage 202 work together to achieve fast and stable dynamic focusing, improving detection efficiency and reliability.

[0069] The optical focusing system 201 mainly includes a scanning focusing device 2011, a light source 2012, an interference beam splitting module 2013, an interference signal collection module 2014; a control processing unit 2015, a third adjustment mechanism 2016, an illumination modulation module 2017, a third relay mirror group 2018, a second relay mirror group 2019, and a collection and detection module 20110.

[0070] The scanning focusing device 2011 includes an interference scanning module 20111 and a first adjustment mechanism 20112.

[0071] The interferometric scanning module 20111 includes a measurement objective lens 201111, a reference objective lens 201112, and a reference mirror 201113.

[0072] The interference beam splitting module 2013 includes a first beam splitter 20131, a first refracting mirror 20132, and a variable aperture 20133.

[0073] The interference signal collection module 2014 includes a first relay mirror group 20141 and a focusing sensor 20142.

[0074] The control processing unit 2015 is connected to the interference signal collection module 2014, the collection and detection module 20110, and the first adjustment mechanism 20112 to achieve focusing and scanning of the target sample.

[0075] The collection and detection module 20110 includes the fourth relay mirror group 201101 and the collection detector 201102.

[0076] First, some necessary explanations will be given regarding the optical focusing system 201 and the motion stage 202. Figure 2 For a detailed description of all elements of the semiconductor device 20 shown, please refer to the following embodiments.

[0077] The motion stage 202 can be a multi-degree-of-freedom precision displacement stage, such as having translational degrees of freedom perpendicular to the optical axis and rotational degrees of freedom about the optical axis, to achieve precise positioning of the target sample in the horizontal plane.

[0078] The motion stage 202 carries the target sample and moves it to a predetermined position according to the preset measurement point coordinates. It then keeps the target sample stable so that the optical focusing system 201 can perform focusing and scanning operations.

[0079] The optical focusing system 201 includes an interferometric scanning module 20111, a light source 2012, an interferometric beam splitting module 2013, and an interferometric signal collection module 2014. It is used to focus on and detect the target sample. Among them: The light source 2012 is located on the incident light side of the interference beam splitting module 2013 and is used to generate illumination light.

[0080] The interference beam splitting module 2013 is located on the light-emitting side of the light source 2012 and is used to split the illumination light provided by the light source 2012 to obtain the measurement light and the reference light.

[0081] Interference scanning module 20111 is disposed on the light-emitting side of interference beam splitting module 2013, and is used to receive measurement light and reference light generated by interference beam splitting module 2013. It includes measurement objective lens 201111, reference objective lens 201112, and reference reflector 201113, wherein: The measurement objective lens 201111 is set in the measurement optical path (the transmission optical path of the measurement light) to project the measurement light onto the surface of the target sample and to receive the measurement signal light reflected back by the target sample.

[0082] The reference objective 201112 is disposed in the reference optical path (the transmission optical path of the reference light) and is used to focus the reference light onto the reference mirror 201113 and receive the reference signal light reflected back by the reference mirror 201113. The reference optical path is parallel to the measurement optical path. The reference mirror 201113 is disposed at the end of the reference optical path and is used to reflect the reference light back to the reference objective 201112.

[0083] The interference signal collection module 2014 is set in the converging optical path where the measurement signal light and the reference signal light converge. It is used to collect the measurement signal light and the reference signal light, and determine the target focusing position of the measurement objective lens 201111 and the target sample based on the measurement signal light and the reference signal light. The measurement objective lens 201111 is moved according to the target focusing position to achieve focusing on the target sample.

[0084] like Figure 2 The semiconductor device 20 shown, because the reference optical path and the measurement optical path are parallel, only requires simultaneous movement of the components in the interferometric scanning module 20111. Regardless of how the interferometric scanning module 20111 moves, the optical path length of the measurement light reaching the output end of the measurement objective 201111 and the optical path length of the reference light reaching the output end of the reference objective 201112 always remain equal (equivalent to...). Figure 1 In this context, Zm=Zr, therefore, by simultaneously moving the components in the interferometric scanning module 20111, the distance between the target sample and the measurement objective lens 201111 can be changed (equivalent to...). Figure 1 In this embodiment of the application, scanning and focusing can be achieved simply by moving the measurement objective lens 201111, the reference objective lens 201112, and the reference mirror 201113.

[0085] As can be seen, in this embodiment, the reference optical path and the measurement optical path are parallel through the component configuration in the optical focusing system 201. Therefore, it is only necessary to move the components in the interferometric scanning module 20111 at the same time to ensure that the optical path at the light-emitting end of the measurement light reaching the measurement objective 201111 and the optical path at the light-emitting end of the reference light reaching the reference objective 201112 remain equal, thereby reducing the overall motion mass, reducing the load on the focusing mechanism, increasing the focusing speed, and thus improving the working efficiency of the semiconductor device 20.

[0086] Example 2 The above-described embodiments provide a semiconductor device 20 that reduces overall motion mass and improves operating efficiency by achieving parallelism between the reference optical path and the measurement optical path. Based on this, this application first describes the detailed structure of the optical focusing system 201 in the semiconductor device 20. Please refer to [link to relevant documentation]. Figure 3 , Figure 3 This is a schematic diagram of an optical focusing system 201 provided in an embodiment of this application. The optical focusing system 201 includes a scanning focusing device 2011; an interference beam splitting module 2013; an interference signal collection module 2014; and a control processing unit 2015. The interference signal collection module 2014 is connected to the control processing unit 2015, wherein: The scanning and focusing device 2011 specifically includes an interferometric scanning module 20111 and a first adjustment mechanism 20112. The first adjustment mechanism 20112 is used to change the position of the interferometric scanning module 20111 to achieve scanning and focusing of the target sample. The interferometric scanning module 20111 includes a measurement objective lens 201111, a reference objective lens 201112, and a reference mirror 201113. The first adjustment mechanism 20112 is connected to the interferometric scanning module 20111 and is controlled by the control processing unit 2015 to move the interferometric scanning module 20111. For a description of the interferometric scanning module 20111, please refer to the relevant content in the related embodiments; it will not be described in detail here.

[0087] Light source 2012 is positioned on the incident light side of the interference beam splitting module 2013 to generate illumination light. Light source 2012 provides the initial light input to the entire optical focusing system 201, serving as the light energy source for the system to achieve interference focusing and sample measurement. This light source 2012 can be a broadband light source, such as a superluminescent diode or a halogen lamp, which has a wide output spectral range and can provide illumination light with a low coherence length. This is beneficial for obtaining interference signals with clear envelope characteristics during interference focusing, facilitating the identification of the zero optical path difference position.

[0088] As another example, the light source 2012 can be a narrowband light source, such as a laser diode or a solid-state laser, which has a narrow output spectral width and a long coherence length, and can provide high-brightness illumination light, suitable for weakly reflective samples or high-precision focusing scenarios.

[0089] In the optical path layout, the light outlet of the light source is aligned with the light incident side of the interference beam splitter module 2013, and the illumination light generated by the light source 2012 is directly incident on the interference beam splitter module 2013. To ensure the stability and uniformity of the illumination light, collimating or homogenizing elements, such as collimating lenses or homogenizing rods, can also be set between the light source 2012 and the interference beam splitter module 2013 to improve the quality of the incident beam.

[0090] The interference beam splitting module 2013 is located on the light-emitting side of the light source 2012 and is used to split the externally provided illumination light to obtain the measurement light and the reference light.

[0091] Specifically, after the illumination light is split into measurement light and reference light by the interference beam splitter module 2013, the measurement light is projected onto the measurement light path in the scanning focusing device 2011, and the reference light is projected onto the reference light path. The two lights are reflected by the target sample and the reference reflector 201113 respectively to form measurement signal light and reference signal light.

[0092] Furthermore, to achieve parallel propagation of the two beams, the interference beam splitter module 2013 includes one or more components such as a beam splitter, a refracting mirror, and an optical mirror to achieve parallel output of the measurement beam and the reference beam.

[0093] As an example, the interferometric beam splitter module 2013 may include a combination of a polarization beam splitter and a reflective element. The illumination light is split into a measurement beam and a reference beam with mutually perpendicular polarization states by the polarization beam splitter. The two beams are emitted in different directions and then their angles are corrected by the reflective elements in their respective optical paths, so that the two beams enter the measurement objective and the reference objective in a parallel and unidirectional manner.

[0094] As another example, the interferometric beam splitter 2013 includes an optical fiber beam splitter that splits the input illumination light into two optical fiber outputs. The mechanical structure of the optical fiber collimator ensures that the propagation directions of the two output beams remain parallel.

[0095] As another example, the interferometric beam splitter module 2013 includes an optical mirror with a certain thickness. Illumination light is input to the front surface of the optical mirror and reflected to obtain measurement light. The illumination light is transmitted in the optical mirror to the rear surface and reflected by the rear surface of the optical mirror to output reference light.

[0096] The interference signal collection module 2014 is set in the converging optical path to collect the measurement signal light formed by the measurement light after being reflected by the target sample and the reference signal light formed by the reference light after being reflected by the target sample. The converging optical path is the path through which the measurement signal light and the reference signal light converge.

[0097] Specifically, the interference signal collection module 2014 includes a photoelectric sensor, such as a photodiode or camera, for converting the received interference light signal into an electrical signal output. For example... Figure 3 The convergence optical path shown is the path through which the measurement signal light and the reference signal light converge. During the scanning process, the interference signal collection module 2014 continuously collects the interference signal intensity values ​​at a preset sampling frequency.

[0098] Please see Figure 4 , Figure 4 This is a schematic diagram of the structure of a control processing unit 2015 provided in an embodiment of this application. The control processing unit 2015 has a built-in controller 20152 for the processor 20151. The processor 20151 is used to determine the target focus position of the interference scanning module 20111 by the interference signal generated by the change of the optical path difference between the measurement signal light and the reference signal light.

[0099] Specifically, processor 20151 first acquires sequence data of the interference signal intensity changing with the scanning position to construct an interference pattern; then, it performs signal processing on the interference pattern, such as extracting the scanning position corresponding to the peak position of the interference envelope; finally, it determines the target focus position based on the coordinates corresponding to the scanning position. Processor 20151 can be a device with data processing capabilities, such as a digital signal processor, a field-programmable gate array, or a central processing unit.

[0100] The controller 20152 is used to control the first adjustment mechanism 20112 to drive the interferometric scanning module 20111 to move to the target focusing position.

[0101] Specifically, the controller 20152 generates a control command based on the target focus position determined by the processor 20151, and outputs the control command to the first adjustment mechanism 20112.

[0102] As an example, the controller 20152 is a microcontroller unit or application-specific integrated circuit that integrates a position closed-loop control algorithm. Based on the deviation between the target focus position and the current actual position, it calculates the driving amount and driving direction, and controls the first adjustment mechanism 20112 to drive the interferometric scanning module 20111 to move along the measurement optical path to the target focus position, thereby completing the focusing operation.

[0103] As can be seen, the optical focusing system 201 generates parallel measurement and reference beams through the interference beam splitting module 2013, then uses the interference signal collection module 2014 to acquire the interference signal of the two signal beams, and the control processing unit 2015 calculates the target focus position based on the interference signal. Based on the target focus position, it controls the interference scanning module 20111 to quickly achieve focus. Since the interference scanning module 20111 moves independently of other optical components, the optical focusing system 201 can effectively reduce motion load and improve focus response speed while achieving high-precision focus positioning.

[0104] Optionally, the interference beam splitting module includes: a first beam splitter and a first refracting mirror, wherein: the first beam splitter is disposed on the light-emitting side of the light source, and is used to split the illumination light to obtain a measurement light and a reference light, and transmit the measurement light to the measurement objective lens, and transmit the reference light to the first refracting mirror; the first refracting mirror is disposed in the reference optical path, and is used to deflect the reference light so that the deflected reference optical path is parallel to the measurement optical path, and transmit the refracted reference light to the reference objective lens.

[0105] Specifically, please refer to Figure 5 , Figure 5 This is a schematic diagram of the structure of an interference beam splitter 2013 provided in an embodiment of this application, wherein the interference beam splitter 2013 includes a first beam splitter 20131 and a first refracting mirror 20132.

[0106] The first beam splitter 20131 is disposed on the light-emitting side of the light source 2012. As an example, the first beam splitter 20131 is specifically a beam splitting prism or a flat beam splitter, which has a beam-splitting film layer inside, capable of splitting the incident illumination light into two beams according to a preset transmission-reflection ratio. One beam serves as the measurement light and is transmitted along the measurement optical path to the measurement objective lens 201111 in the scanning focusing device 2011; the other beam serves as the reference light and is transmitted to the first refracting mirror 20132.

[0107] A first refracting mirror 20132 is disposed in the reference optical path. As an example, the first refracting mirror 20132 can be a plane mirror or a total internal reflection prism, used to change the propagation direction of the reference light. The reference light, after exiting the first beam splitter 20131, propagates along a first direction and is incident on the first refracting mirror 20132. After reflection by the first refracting mirror 20132, the propagation direction of the reference light is deflected from the first direction to a second direction. This second direction is configured to be parallel to the direction of the measurement optical path, thereby ensuring that the deflected reference optical path remains parallel to the measurement optical path. The deflected reference light is then transmitted to the reference objective lens 201112.

[0108] By refracting the reference optical path through the first refracting mirror 20132, the reference optical path is adjusted to be parallel to the measurement optical path, which lays the foundation for achieving stable interference when the two optical paths converge later.

[0109] As can be seen, the interference beam splitting module 2013 completes the beam splitting of the illumination light through the first beam splitter 20131, and then uses the first refracting mirror 20132 to fold the direction of the reference optical path, so that the reference optical path and the measurement optical path remain parallel in space; thus realizing a parallel optical path structure, when the scanning focusing device 2011 moves in a single direction, it can simultaneously change the effective optical path length of the reference optical path and the measurement optical path in that direction, realizing continuous adjustment of the optical path difference between the two optical paths. In addition, by concentrating the optical path folding function in the interference beam splitting module 2013, the scanning focusing device 2011 does not need to integrate the interference beam splitting module 2013, which significantly reduces the weight of the interference scanning module 20111, which is beneficial to improving the speed and stability of the interference scanning module 20111, and further improves the working efficiency of the semiconductor device 20.

[0110] Optionally, the system further includes: a third adjustment mechanism connected to the first refracting mirror; the third adjustment mechanism is used to adjust the position and orientation of the first refracting mirror so that the reference optical path is parallel to the measurement optical path.

[0111] Specifically, please refer to Figure 6 , Figure 6 This is a schematic diagram illustrating the adjustment dimension of a third adjustment mechanism 2016 provided in an embodiment of this application. The optical focusing system 201 further includes a third adjustment mechanism 2016, which is connected to a first refracting mirror 20132. The first refracting mirror 20132 is disposed in the reference optical path and is used to change the propagation direction of the reference light. The third adjustment mechanism 2016 is used to adjust the pose of the first refracting mirror 20132 to achieve parallelism calibration between the reference optical path and the measurement optical path.

[0112] The third adjustment mechanism 2016 can adopt an adjustment structure composed of multiple top pull screws and / or flexible hinges to change the pitch angle and / or yaw angle of the first refracting mirror 20132, thereby fine-tuning the emission direction of the reference light.

[0113] As an example, please refer to Figure 6 , Figure 6 This application provides a schematic diagram of the adjustment dimensions of a third adjustment mechanism 2016, wherein the third adjustment mechanism 2016 may include multiple adjustment dimensions, including an Ry dimension of rotation about the Y-axis (the Y-axis is perpendicular to the x-axis). Figure 6 One or more of the following: plane, Rz dimension rotating about the Z-axis, Rx dimension rotating about the X-axis, and x dimension moving along the X-axis (the X-axis is parallel to the illumination path).

[0114] During the assembly or use of the optical focusing system 201, when a parallelism deviation between the reference optical path and the measurement optical path is detected, the position of the first refracting mirror 20132 is adjusted by operating the third adjustment mechanism 2016 until the optical axes of the two light paths are parallel to each other. This adjustment process can be combined with a parallelism detection instrument or assisted by calibration based on the quality of the interference signal to ensure that the reference optical path and the measurement optical path maintain a strict parallel relationship.

[0115] It can be seen that by setting a third adjustment mechanism 2016 connected to the first refracting mirror 20132, the direction of the reference optical path can be independently and precisely adjusted, achieving parallelism calibration between the reference optical path and the measurement optical path without changing the state of the measurement optical path. This independent adjustment method avoids adding additional adjustment structures to the scanning and focusing device 2011, thus maintaining the lightweight design of the interferometric scanning module 20111 while ensuring optical path accuracy, which is beneficial to improving scanning speed and focusing efficiency.

[0116] Optionally, the interferometric signal collection module includes: a first relay lens group and a focusing sensor; the first relay lens group is disposed in front of the focusing sensor and is used to converge the measurement signal light and the reference signal light to the focusing sensor; the focusing sensor is used to receive the measurement signal light and the reference signal light.

[0117] Specifically, the interference signal collection module 2014 receives the measurement signal light and the reference signal light through a relay mirror group and a sensor.

[0118] Please see Figure 7 , Figure 7 This is a schematic diagram of the structure of the interference signal collection module 2014 provided in an embodiment of this application. In this embodiment, the interference signal collection module 2014 includes a first relay lens group 20141 and a focusing sensor 20142. The first relay lens group 20141 is disposed in the optical path before the focusing sensor 20142, located on the merging optical path formed by the convergence of the measurement signal light and the reference signal light. After the measurement signal light and the reference signal light merge, they form an interference beam. This interference beam enters the first relay lens group 20141, which focuses the interference beam onto the focusing sensor 20142.

[0119] As an example, the first relay lens group 20141 may include a lens group consisting of one or more lenses, the optical parameters of which are designed according to the photosensitive surface size and position of the focus sensor to ensure that the interference beam is efficiently focused and matched to the receiving aperture of the focus sensor 20142.

[0120] Furthermore, the first relay lens group 20141 may also include an adjustment device for adjusting the aperture of the beam incident on the focus sensor to control the signal intensity or suppress stray light.

[0121] The focus sensor 20142 is positioned near the convergence point of the first relay lens group 20141 and is used to receive the converged measurement signal light and reference signal light. The focus sensor 20142 can be a photodiode, a charge-coupled device camera, or a semiconductor camera, etc., which converts the received interference light signal into an electrical signal or a digital signal for output.

[0122] During the scanning and focusing process, the first adjustment mechanism 20112 drives the interferometric scanning module 20111 to move along the measurement optical path. The optical path difference between the measurement signal light and the reference signal light changes continuously, causing the intensity of the merged interference beam to change accordingly. The first relay lens group 20141 focuses the interference beam onto the focus sensor 20142. The focus sensor 20142 continuously acquires the interference signal at a preset sampling frequency and transmits the acquired signal to the processor 20151 for further processing.

[0123] As can be seen, the interference beam is focused onto the focusing sensor 20142 by the first relay lens group 20141. The interference signal collection module 2014 can efficiently collect the interference signal generated by the measurement signal light and the reference signal light, and convert the optical signal into an electrical signal for analysis by the processor 20151. While ensuring signal collection efficiency, it provides a reliable data foundation for subsequent interference signal processing and target focusing position determination.

[0124] Optionally, the interference beam splitting module further includes a variable aperture; the variable aperture is disposed in the reference optical path, and the variable aperture can be disposed at any position between the first beam splitter and the reference mirror, and the variable aperture is used to open or close the reference optical path.

[0125] Specifically, please refer to Figure 8 , Figure 8 This is a schematic diagram of the structure of an interference beam splitter module 2013 provided in an embodiment of this application. The interference beam splitter module 2013 also includes a variable aperture 20133, which is disposed in the reference optical path and used to turn the reference optical path on or off. By controlling the light transmission state of the variable aperture 20133, selective switching of the reference optical path can be achieved in different operating modes. The variable aperture 20133 can be disposed between the first beam splitter 20131 and the first refracting mirror 20132. In some possible embodiments, the variable aperture 20133 can also be disposed at any point on the reference optical path between the first beam splitter 20131 and the reference reflector 201113.

[0126] The variable aperture 20133 can adopt a mechanical structure, such as an optical switch device or a filter wheel, to physically block or open the reference optical path. For example, the variable aperture 20133 with a mechanical structure contains movable light-blocking blades. The opening and closing of the blades are controlled by electromagnetic drive or motor drive, thereby realizing the physical blocking or opening of the reference optical path.

[0127] During system operation, the variable aperture 20133 switches states according to the current operating mode. When the optical focusing system 201 performs a focusing operation, the controller 20152 controls the variable aperture 20133 to open the reference optical path, allowing the reference light to be smoothly transmitted to the reference objective lens 201112 and the reference mirror 201113, and return to form a reference signal light, which generates an interference signal with the measurement signal light for determining the focus position. When focusing is complete and the optical focusing system 201 switches to the measurement mode, the controller 20152 controls the variable aperture 20133 to close the reference optical path, blocking the transmission of the reference light, avoiding interference from the reference light to the measurement signal, and ensuring that the measurement signal light can be received independently for sample measurement.

[0128] As can be seen, by setting a variable aperture 20133 in the reference optical path, the interference beam splitting module 2013 can flexibly control the on / off state of the reference optical path in different working modes. When focusing, the reference optical path is turned on to ensure the normal generation of the interference signal, and when measuring, the reference optical path is turned off to avoid the interference of the reference light on the measurement signal. This selective on / off control enables the system to quickly switch between the focusing mode and the measurement mode, thus improving the signal-to-noise ratio of the measurement signal while ensuring focusing accuracy.

[0129] Optionally, the optical focusing system further includes an illumination modulation module; the illumination modulation module is disposed between the light source and the interference beam splitting module and is used to modulate the illumination light.

[0130] Specifically, the optical focusing system 201 also includes an illumination modulation module 2017, which is disposed between the light source 2012 and the interference beam splitter 2013, and is used to modulate the illumination light. By pre-modulating the illumination light incident on the interference beam splitter 2013, the optical characteristics of the illumination light can be changed to adapt to the needs of different samples or different measurement scenarios.

[0131] The illumination modulation module 2017 specifically includes zoom lens groups or beam expanders, etc., for independently or in combination modulating the shape, size, position, etc. of the illumination pupil of the illumination light.

[0132] For example, please refer to Figure 9 , Figure 9This is a schematic diagram of the structure of a light source 2012 and an illumination modulation module 2017 provided in an embodiment of this application. In this example, the optical focusing system 201 further includes a third relay lens group 2018, located between the light source 2012 and the illumination modulation module 2017.

[0133] After the light source 2012 generates illumination light, it is collimated by the third relay mirror group 2018 and then modulated by the incident illumination modulation module 2017. Finally, the modulated illumination light is input into the subsequent interference beam splitting module 2013.

[0134] As can be seen, by setting the illumination modulation module 2017 between the light source 2012 and the interferometric beam splitter 2013, the optical focusing system 201 can flexibly adjust the illumination light to adapt to different measurement conditions. Since the illumination modulation module 2017 is arranged independently of the interferometric scanning module and does not move with the scanning motion, the illumination modulation state remains stable during rapid focusing scanning, avoiding changes in the illumination mode caused by scanning motion, thereby ensuring the stability of the measurement performance.

[0135] Optionally, the optical focusing system further includes: a second relay lens group and a collection and detection module; the second relay lens group is disposed on the light-incident side of the collection and detection module, and is used to transmit the measurement signal light and the reference signal light to the interferometric signal collection module before the interferometric scanning module moves to the target focusing position; and to transmit the measurement signal light to the collection and detection module after the interferometric scanning module moves to the target focusing position; the collection and detection module is disposed at the end of the measurement optical path, and is used to collect the measurement signal light and generate measurement data of the target sample based on the measurement signal light.

[0136] Specifically, the optical focusing system 201 further includes a second relay lens group 2019 and a collection and detection module 20110. The second relay lens group 2019 is disposed on the incident light side of the collection and detection module 20110, located on the confluence optical path of the measurement signal light and the reference signal light, and is used to transmit the corresponding beam to the corresponding receiving module according to different system operating modes. The collection and detection module 20110 is disposed at the end of the measurement optical path, and is used to collect the measurement signal light in measurement mode and generate measurement data of the target sample.

[0137] The second relay lens group 2019 performs the dual functions of optical path switching and beam transmission in the optical focusing system 201. Before the interferometric scanning module 20111 moves to the target focusing position, the system is in focusing mode. At this time, the second relay lens group 2019 transmits both the measurement signal light and the reference signal light to the interferometric signal collection module 2014. After the measurement signal light returns through the measurement objective lens 201111, and the reference signal light returns through the reference objective lens 201112, the two signal beams meet and interfere in the merging optical path. The second relay lens group 2019 receives this interference beam and projects it onto the light inlet of the interferometric signal collection module 2014 through internal optical elements, providing an interference signal for determining the focusing position.

[0138] The second relay mirror group 2019 may include a second beam splitter or a second refracting mirror, which deflects the light beam into the optical path of the interferometric signal collection module 2014 in focusing mode. After the interferometric scanning module 20111 moves to the target focusing position, the system switches to measurement mode, at which time the second relay mirror group 2019 transmits the measurement signal light separately to the collection and detection module 20110.

[0139] For example, please refer to Figure 10 , Figure 10 A schematic diagram of a second relay mirror group 2019 and a collection and detection module 20110 provided in this application embodiment is shown. The second relay mirror group 2019 is disposed in the merging optical path of the measurement signal light and the reference signal light, as shown below. Figure 10 In the example structure, in focus mode, the second relay lens group 2019 transmits the measurement signal light and reference signal light along the path shown in the example. Figure 10 The first optical path shown transmits the signal to the interference signal collection module 2014, and in measurement mode, the measurement signal light is transmitted along the path shown. Figure 10 The second optical path shown transmits to the collection and detection module 20110.

[0140] The collection and detection module 20110 is located at the end of the measurement optical path and is used to receive the measurement signal light from the second relay mirror group 2019. As an example, the collection and detection module 20110 may include a fourth relay mirror group 201101 and a collection detector 201102.

[0141] The fourth relay mirror group 201101 consists of one or more lenses and is used to relay and image the received measurement signal light to match the photosensitive surface size and position of the collection detector 201102.

[0142] The collector detector 201102 is used to convert optical signals into electrical or digital signals and generate measurement data of the target sample. The collector detector 201102 can be a photomultiplier tube, a charge-coupled device camera, or a complementary metal-oxide-semiconductor camera, and the appropriate detector type is selected according to the measurement requirements.

[0143] Please see Figure 11 , Figure 11 This is a schematic diagram of the structure of a collection and detection module 20110 provided in an embodiment of this application. The collection and detection module 20110 includes a fourth relay lens group 201101 and a collection detector 201102. The fourth relay lens group 201101 may include a lens group composed of one or more lenses. Its optical parameters are designed according to the photosensitive surface size and position of the collection detector 201102 to ensure that the measurement signal light is efficiently focused and matched with the receiving aperture of the collection detector 201102.

[0144] The collecting detector 201102 is positioned at the convergence point of the fourth relay mirror group 201101 to receive the converged measurement signal light. The collecting detector 201102 can be a photomultiplier tube, a charge-coupled device (CCD) camera, or a complementary metal-oxide-semiconductor (CMOS) camera, etc. In measurement mode, the collecting detector 201102 converts the received interference light signal into an electrical or digital signal, and ultimately generates measurement data for the target sample. The measurement data specifically includes one or more of the following: image of the target sample, detection results, defect type, etc.

[0145] As can be seen, by setting up the fourth relay lens group 201101 and the collection detector 201102, the interference beam is transmitted to the interference signal collection module 2014 via the second relay lens group 2019 in focusing mode, and the measurement signal light is transmitted to the collection detector 201102 via the fourth relay lens group 201101 in measurement mode, thus avoiding optical path conflicts and signal interference between the two modes. This optical path design simplifies the system structure while ensuring that focusing and measurement functions are implemented independently, providing reliable optical architecture support for the efficient operation of the system.

[0146] As can be seen from the optical focusing system 201 described in the above embodiments, the scanning focusing device 2011 reduces the mass of components that need to move during the focusing process, thus improving scanning efficiency and consequently increasing the working efficiency of the semiconductor manufacturing equipment. Simultaneously, components related to the optical path folding function and the parallelism calibration function between the reference optical path and the measurement optical path are also avoided on the scanning focusing device 2011, further improving scanning speed and focusing efficiency. Furthermore, the integration with the illumination modulation module 2017 ensures the stability of measurement performance.

[0147] Example 3 Based on the optical focusing system 201 described in the above-mentioned embodiments, this application also provides a more detailed scanning focusing device 2011, which can be applied to any of the optical focusing systems 201 described in the above-mentioned embodiments. For a detailed description of the optical focusing system 201, please refer to the relevant content in the above-mentioned embodiments, which will not be repeated here.

[0148] Please see Figure 12 , Figure 12 This is a schematic diagram of a scanning focusing device 2011 provided in an embodiment of this application. The scanning focusing device 2011 includes: an interference scanning module 20111 and a first adjustment mechanism 20112, wherein the first adjustment mechanism 20112 is connected to the interference scanning module 20111; the interference scanning module 20111 includes a measuring objective lens 201111, a reference objective lens 201112 and a reference reflecting mirror 201113, wherein.

[0149] The measurement objective lens 201111 is set in the measurement optical path to project the measurement light onto the surface of the target sample and to receive the measurement signal light reflected back by the target sample.

[0150] Reference objective 201112 is disposed in the reference optical path and is used to focus the reference light onto reference mirror 201113 and receive the reference signal light reflected back by reference mirror 201113. The reference optical path is parallel to the measurement optical path. Reference mirror 201113 is disposed at the end of the reference optical path and is used to reflect the reference light back to reference objective 201112.

[0151] The first adjustment mechanism 20112 is used to drive the interferometric scanning module 20111 to scan along the measurement optical path and to drive the interferometric scanning module 20111 to move to the target focusing position. The target focusing position is determined by the interferometric signal collection module 2014 by acquiring the interference signal generated by the change of optical path difference between the measurement signal light and the reference signal light during the scanning process of the interferometric scanning module 20111 along the measurement optical path.

[0152] Specifically, the measurement objective 201111 is located in the measurement optical path, specifically after the interference beam splitter module 2013. The externally provided measurement light is output from the interference beam splitter module 2013 and enters the measurement objective 201111. The measurement objective 201111 projects the measurement light onto the surface of the target sample (such as a mask or wafer). After being reflected by the target sample, the measurement light forms a measurement signal light. This measurement signal light returns along the measurement optical path and is received by the measurement objective 201111, and finally inputs into the interference signal collection module 2014.

[0153] The reference objective 201112 is disposed in the reference optical path, specifically between the interference beam splitter module 2013 and the reference mirror 201113. It is used to focus the reference light provided by the interference beam splitter module 2013 onto the reference mirror 201113 and receive the reference signal light reflected back by the reference mirror 201113. The measurement signal light returns along the measurement optical path and is received by the measurement objective 201111, and finally input into the interference signal collection module 2014. The reference optical path and the measurement optical path are parallel.

[0154] Reference mirror 201113 is located at the end of the reference optical path and is used to reflect the reference light back to reference objective 201112.

[0155] During the interferometric focusing process, the measurement light provided by the interferometric beam splitting module 2013 enters the measurement optical path, and the measurement objective lens 201111 projects the measurement light onto the surface of the target sample. After being reflected by the target sample, the measurement light forms a measurement signal light, which returns along the measurement optical path and is received by the measurement objective lens 201111.

[0156] Meanwhile, the reference light provided by the interference beam splitter module 2013 enters the reference optical path, and the reference objective lens 201112 is set in the reference optical path to focus the reference light onto the reference mirror 201113 located at the end of the reference optical path. After being reflected by the reference mirror 201113, the reference light forms a reference signal light, which returns along the reference optical path and is received by the reference objective lens 201112.

[0157] The first adjustment mechanism 20112 specifically includes one or more driving units, and is connected to the measurement objective lens 201111, reference objective lens 201112, and reference reflector 201113 in the interferometric scanning module 20111, either individually or simultaneously, through one or more driving units. The first adjustment mechanism 20112 can be mounted on the fixed frame of the semiconductor device 20 to control the movement of the interferometric scanning module 20111 independently of other unrelated components such as the light source 2012 and the interferometric beam splitting module 2013.

[0158] To achieve precise linear motion of the interference scanning module 20111, one or more drive units in the first adjustment mechanism 20112 are specifically a combination structure formed by one or more of the following: motor, electric motor, or guide rail.

[0159] During the focusing process, the first adjustment mechanism 20112 is used to drive the interferometric scanning module 20111 to scan along the measurement optical path and to drive the interferometric scanning module 20111 to move to the target focusing position. The target focusing position refers to the spatial position of the interferometric scanning module 20111 when the reference light is focused on the surface of the target sample after being emitted from the measurement objective lens 201111 (i.e., the target sample is at the optimal focal plane). At this position, the optical path difference between the measurement optical path and the reference optical path is zero.

[0160] The target focus position is determined by the interference signal generated by the change of optical path difference between the measurement signal light and the reference signal light. Before the driving interferometric scanning module 20111 scans along the measurement optical path, the reference objective lens 201112 and the reference mirror 201113 have already been focused, that is, the reference light is focused on the reference mirror 201113 by the reference objective lens 201112, and the reference optical path and the measurement optical path are parallel.

[0161] Under the above conditions, the first adjustment mechanism 20112 is used to drive the interferometric scanning module 20111 to scan the surface of the target sample along the measurement optical path in the area between the target sample and the interferometric beam splitting module (such as from top to bottom or from bottom to top).

[0162] During the scanning process, the optical path difference between the measurement optical path and the reference optical path changes, and the interference signal collection module 2014 obtains the changing interference signal. For example, please refer to [link to relevant documentation]. Figure 13 , Figure 13 This is a schematic diagram of the interference signal generated by the measurement signal light and the reference signal light as the scanning position changes, provided in an embodiment of this application. The horizontal axis represents the scanning position of the target sample scanned by the measurement objective lens 201111, and the vertical axis represents the interference intensity of the interference signal. The scanning position corresponding to the point with the strongest interference signal can be determined based on the point with the strongest interference signal, and then the target focus position can be determined based on the scanning position corresponding to the point with the strongest interference signal.

[0163] After determining the target focus position, the first adjustment mechanism 20112 drives the interferometric scanning module 20111 to move to the target focus position, and the focal point of the measurement beam is located on the surface of the target sample, thereby completing the focusing of the measurement objective lens 201111 and the target sample.

[0164] like Figure 12 During the scanning and focusing process, the measurement objective lens 201111, reference objective lens 201112, and reference mirror 201113 move together with the first adjustment mechanism 20112. Therefore, during the scanning process, the optical path length of the measurement light reaching the output end of the measurement objective lens 201111 and the optical path length of the reference light reaching the output end of the reference objective lens 201112 remain equal (i.e., Zm=Zr). The first adjustment mechanism 20112 moves the interference scanning module 20111, which only changes the distance between the target sample and the measurement objective lens 201111. Therefore, in this embodiment, the scanning and focusing device 2011 only needs to move the measurement objective lens 201111, reference objective lens 201112, and reference mirror 201113 to achieve scanning and focusing.

[0165] In some possible implementations, the reference objective 201112 and the measuring objective 201111 share the same housing, which is fixed to the stator and does not move with the drive of the first adjustment mechanism 20112. By integrating the reference objective 201112 and the measuring objective 201111 into the same housing, the relative positional relationship between the two is stably fixed.

[0166] When the interferometric scanning module 20111 performs a scan, only the measurement objective lens 201111, the reference objective lens 201112, and the reference mirror 201113 move with the first adjustment mechanism 20112, while the housing supporting these objectives remains stationary.

[0167] To achieve movement of only the objective lens without moving the housing, the first adjustment mechanism 20112 can employ an internally driven structure. Specifically, the housing serves as a support base fixed to the stator (e.g., frame or base) of the optical focusing system 201, and a guide rail or guide groove extending along the optical axis is provided inside the housing. The measuring objective lens 201111, the reference objective lens 201112, and the reference mirror 201113 are respectively mounted in their corresponding lens barrels or mounts, and the two lens barrels or mounts are fixed together by connectors to form an integral moving component. This integral moving component is slidably mounted on the guide rail inside the housing.

[0168] This structural design eliminates the need for separate housings for the measurement objective 201111, reference objective 201112, and reference mirror 201113, further reducing the mass of the scanning moving parts. Since the housings and their internal structures do not participate in the movement, the scanning load is further reduced. Simultaneously, it improves the temperature consistency between the reference objective 201112 and the measurement objective 201111, enhancing focusing accuracy.

[0169] As can be seen, the scanning and focusing device 2011 sets the reference optical path and the measurement optical path as parallel structures, and integrates the measurement objective lens 201111, the reference objective lens 201112, and the reference reflector 201113 into the interference scanning module 20111. Therefore, when focusing and scanning, the first adjustment mechanism 20112 only needs to drive the interference scanning module 20111 to scan and focus along the optical path direction, without having to drive other components such as the light source 2012 and the interference beam splitting module 2013 at the same time. This effectively reduces the overall mass of the components that the first adjustment mechanism 20112 needs to drive, reduces the scanning load, increases the scanning speed, shortens the focusing time, and thus improves the working efficiency of the semiconductor device 20.

[0170] Optionally, the scanning focusing device further includes: a second adjustment mechanism connected to a reference objective lens, the second adjustment mechanism being used to adjust the pose of the reference objective lens; or, the second adjustment mechanism connected to a reference mirror, the second adjustment mechanism being used to adjust the pose of the reference mirror; or, the second adjustment mechanism connected to both the reference objective lens and the reference mirror, the second adjustment mechanism being used to simultaneously adjust the pose of both the reference objective lens and the reference mirror.

[0171] Specifically, the scanning focusing device 2011 further includes a second adjustment mechanism 20113, which is located on the reference objective lens 201112 and / or the reference mirror 201113, or located on the semiconductor device 20 body and connected to the reference objective lens 201112 and / or the reference mirror 201113.

[0172] The second adjustment mechanism 20113 specifically includes one or more drive units, which are connected to the reference objective lens 201112 and / or the reference mirror 201113 respectively or simultaneously. The one or more drive units are specifically a combination structure formed by one or more of the following: motor, electric motor, or guide rail.

[0173] The second adjustment mechanism 20113 is used to achieve precise adjustment of the optical path inside the interferometric scanning module 20111. The second adjustment mechanism 20113 has multiple optional connection methods to adapt to different assembly and adjustment requirements and structural layouts.

[0174] In one possible implementation, the second adjustment mechanism 20113 is directly connected to the reference objective lens 201112, and the orientation of the reference optical path or the focal position is changed by adjusting the pose of the reference objective lens 201112.

[0175] For example, please refer to Figure 14A , Figure 14A This is a schematic diagram of another scanning focusing device 2011 provided in an embodiment of this application, wherein, apart from the interference scanning module 20111 ( Figure 14A (not shown) and the first adjusting mechanism 20112 ( Figure 14A In addition to the reference objective 201112 (not shown), a second adjustment mechanism 20113 is directly connected to the reference objective 201112. The second adjustment mechanism 20113 is used to change the direction or focal position of the reference optical path by adjusting the pose of the reference objective 201112.

[0176] Furthermore, the second adjustment mechanism 20113 includes one or more adjustment dimensions, such as a first dimension (moving along a direction parallel to the X-axis), a second dimension (moving along a direction parallel to the Y-axis), or a third dimension (moving along a direction parallel to the Z-axis), wherein the Z-axis is parallel to the reference optical path, and the X-axis and Y-axis directions are perpendicular to the Z-axis direction. Please refer to [link to relevant documentation]. Figure 14B , Figure 14B A schematic diagram of the adjustment dimension of a second adjustment mechanism 20113 provided in an embodiment of this application is shown below. Figure 14B A schematic diagram of one possible adjustment dimension of the second adjustment mechanism 20113 shown.

[0177] Fine adjustments are made to the spatial position and attitude angle of the reference objective 201112, thereby changing the optical axis orientation of the reference optical path to ensure its parallelism with the measurement optical path and to guarantee precise matching of the focal point of the reference objective 201112 with the position of the reference mirror 201113. This connection method concentrates the adjustment function on the reference objective 201112, resulting in a relatively simple adjustment structure that helps reduce the complexity and weight of the adjustment mechanism.

[0178] In another possible implementation, the second adjustment mechanism 20113 is directly connected to the reference mirror 201113, and the reflection direction or optical path of the reference light is changed by adjusting the pose of the reference mirror 201113.

[0179] The tilt angle and spatial position of the reference mirror 201113 are independently adjusted, thereby changing the reflection direction of the reference light, achieving parallelism calibration between the reference optical path and the measurement optical path, and ensuring that the reference mirror 201113 is precisely positioned at the focal point of the reference objective lens 201112. This connection method concentrates the adjustment function on the reference mirror 201113, and the adjustment process does not affect the fixed state of the reference objective lens 201112, which is beneficial to maintaining the stability of the reference objective lens 201112.

[0180] In another alternative implementation, the second adjustment mechanism 20113 is connected to both the reference objective lens 201112 and the reference mirror 201113, enabling synchronous or independent adjustment of their poses.

[0181] The reference objective lens 201112 and the reference mirror 201113 are adjusted in a coordinated manner. On the one hand, the optical axis of the reference optical path is adjusted to make it parallel to the measurement optical path. On the other hand, the relative positional relationship between the reference mirror 201113 and the reference objective lens 201112 is ensured. This connection method provides more degrees of adjustment freedom, can more flexibly compensate for assembly errors in the reference optical path, and achieve high-precision matching between the reference optical path and the measurement optical path.

[0182] Through any of the above connection methods, the second adjustment mechanism 20113 can make fine adjustments to the optical elements in the reference optical path, thereby compensating for machining and assembly tolerances during assembly or use, or adjusting the reference objective lens 201112 and the reference mirror 201113 before focusing and scanning, ensuring that the reference optical path and the measurement optical path remain strictly parallel, and ensuring that the reference mirror 201113 is accurately located at the focal position of the reference objective lens 201112, thus providing a guarantee for the subsequent generation of high-quality interference signals.

[0183] Furthermore, it should be noted that while the third adjustment mechanism 2016 includes the x-dimensional movement along the X-axis, the adjustment dimension of the second adjustment mechanism 20113 does not include the first dimension. That is, the second adjustment mechanism 20113 does not need to include the function of moving in a direction parallel to the X-axis. Therefore, the components related to moving in a direction parallel to the X-axis can be removed from the first adjustment mechanism 20112, thereby further reducing the adjustment load of the first adjustment mechanism 20112, further reducing the scanning load, and improving the focusing scanning speed.

[0184] It can be seen that by introducing a second adjustment mechanism 20113 connected to the reference objective lens 201112 and / or the reference mirror 201113 into the scanning focusing device 2011, high-precision adjustment and calibration of the reference optical path can be achieved, so that the reference optical path and the measurement optical path remain parallel, thereby ensuring the accuracy and stability of focusing.

[0185] Optionally, the second adjustment mechanism is connected to both the reference objective and the reference mirror, and the scanning focusing device also includes a lens barrel in which the reference objective and the reference mirror are installed, and the second adjustment mechanism is connected to the lens barrel.

[0186] Specifically, the second adjustment mechanism 20113 is connected to both the reference objective lens 201112 and the reference mirror 201113. The scanning focusing device 2011 also includes a lens barrel 201114. The reference objective lens 201112 and the reference mirror 201113 are installed inside the lens barrel 201114, which integrates them into a single unit. The second adjustment mechanism 20113 is connected to the lens barrel, and by adjusting the position and orientation of the lens barrel 201114, synchronous adjustment of the reference objective lens and the reference mirror is achieved.

[0187] For example, please refer to Figure 15 , Figure 15This is a schematic diagram of another scanning focusing device 2011 provided in an embodiment of this application. In this device, the reference objective lens 201112 and the reference mirror 201113 are jointly installed in the lens barrel 201114, and the lens barrel 201114 is adjusted as a whole by the second adjustment mechanism 20113. This reduces the number of independent adjustment components, simplifies the structure of the scanning focusing device 2011, reduces the overall weight, and further reduces the scanning load, which is beneficial to improving the scanning speed. (Reference objective lens 201112)

[0188] As can be seen, by integrating the reference objective lens 201112 and the reference mirror 201113 into the lens barrel 201114, and by adjusting the pose of the lens barrel 201114 as a whole by the second adjustment mechanism 20113, the scanning focusing device 2011 achieves precise optical path calibration while further reducing the scanning load and improving the focusing speed.

[0189] Optionally, the measuring objective and the reference objective share the same objective type and have the same numerical aperture.

[0190] Specifically, the measurement objective 201111 and the reference objective 201112 use the same objective type, which means that the measurement objective 201111 and the reference objective 201112 adopt the same optical design structure, including the parameters, quantity, installation order, type, coating, polarization and other aspects of the optical lenses are consistent.

[0191] In addition, the measurement objective 201111 and the reference objective 201112 have the same numerical aperture, so that the measurement optical path and the reference optical path are highly matched in terms of optical characteristics, including key parameters such as focal length, working distance and light-gathering ability.

[0192] It can be seen that by selecting the same type and configuring the same numerical aperture for the measurement objective 201111 and the reference objective 201112, the scanning focusing device 2011 can achieve good symmetry between the measurement optical path and the reference optical path at the optical path level, thus improving the quality of the interference signal and enhancing the stability of the focusing process and the accuracy of the focus position determination.

[0193] As can be seen from the apparatus in the above-described embodiments, by setting the reference optical path and the measurement optical path to be parallel, the mass of the moving parts is reduced, thereby improving the working efficiency of the semiconductor manufacturing equipment. The second adjustment mechanism 20113 and the lens barrel 201114 further ensure the accuracy and stability of focusing. By selecting the same type and configuring the same numerical aperture for the measurement objective lens 201111 and the reference objective lens 201112, the stability of the focusing process and the accuracy of the focus position determination are enhanced.

[0194] Example 4 Based on the description of the above-described embodiments, this application also provides a focusing control method, applied to the optical focusing system 201 described in the above-described embodiments. Please refer to [link to relevant documentation]. Figure 16 , Figure 16 A flowchart illustrating a focusing control method provided in this application embodiment includes steps S601-S604, including: S601: Control the first adjustment mechanism to drive the interference scanning module to scan along the measurement optical path.

[0195] Specifically, the controller 20152 in the optical focusing system 201 controls the first adjustment mechanism 20112 to drive the interferometric scanning module 20111 to scan along the measurement optical path, and its movement direction is parallel to the optical axis direction of the measurement optical path.

[0196] During scanning, a scanning control command is sent to the first adjustment mechanism 20112 to drive the interferometric scanning module 20111 to move continuously along the optical axis with a preset scanning step size and scanning range. The scanning range needs to cover the expected focal position, that is, to ensure that the optical path difference between the measurement signal light and the reference signal light can pass through the zero optical path difference point during the scanning process.

[0197] Optionally, before controlling the first adjustment mechanism to drive the interferometric scanning module to scan along the measurement optical path, the method further includes: controlling the motion stage carrying the target sample to move to the first measurement position, so that the measurement objective lens measures the first measurement point of the target sample, the first measurement position being located in the measurement plane, and the measurement plane being perpendicular to the measurement optical path.

[0198] Specifically, before controlling the first adjustment mechanism 20112 to drive the interferometric scanning module 20111 to scan along the measurement optical path, the focusing control method further includes controlling the motion stage carrying the target sample to move horizontally to the first measurement position, so as to move the first measurement point of the target sample to directly below the measurement objective lens, ensuring that when the measurement objective lens measures the first measurement point of the target sample, the first measurement point is located within the focusing detection range covered by the measurement optical path.

[0199] The first measurement position is located within the measurement plane, enabling the measurement objective lens 201111 to measure the first measurement point on the target sample.

[0200] The measurement plane is a plane at a fixed height that is perpendicular to the measurement optical path. It is a horizontal plane formed by the X-axis and Y-axis directions. The position of the target sample in this plane determines the specific point being measured.

[0201] As an example, the motion stage can be a multi-degree-of-freedom precision displacement stage, such as having translational degrees of freedom perpendicular to the optical axis and rotational degrees of freedom about the optical axis, used to achieve precise positioning of the target sample in the horizontal plane. The motion stage carries the target sample and moves along a plane perpendicular to the measurement optical path under the command of the controller, according to preset measurement point coordinates. Specifically, the controller 20152 sends position commands to the motion stage driver, which drives the motion stage to move along the X-axis and Y-axis directions, moving the first measurement point on the target sample directly below the measurement optical path, that is, aligning the first measurement point with the optical axis of the measurement objective lens 201111.

[0202] Once the motion stage reaches the first measurement position and stabilizes, the optical focusing system 201 will then perform subsequent focusing and scanning operations.

[0203] As can be seen, by controlling the motion stage to move to the first measurement position before scanning and focusing, this focusing control method achieves pre-alignment of the measurement point with the measurement optical path, providing support for the efficient operation of the overall measurement process.

[0204] Optionally, before controlling the first adjustment mechanism to drive the interferometric scanning module to scan along the measurement optical path, the method further includes: controlling the third adjustment mechanism to adjust the orientation of the refracting mirror so that the reference optical path is parallel to the measurement optical path.

[0205] Specifically, before the first adjustment mechanism 20112 drives the interferometric scanning module 20111 to scan along the measurement optical path, in order to ensure that the reference optical path and the measurement optical path are parallel, the controller 20152 also needs to control the third adjustment mechanism 2016 to adjust the attitude of the first refracting mirror 20132.

[0206] As an example, the controller 20152 sends an adjustment command to the third adjustment mechanism 2016, driving the first refracting mirror 20132 to make fine adjustments around the first and second rotation axes, changing the emission direction of the reference light. During the adjustment process, a parallelism detector or the quality of the interference signal can be used for auxiliary judgment. When the reference light path and the measurement light path are parallel, the adjustment is stopped and the attitude of the first refracting mirror 20132 is locked.

[0207] As can be seen in this embodiment, because the attitude of the first refracting mirror 20132 is calibrated before scanning and focusing, it can be ensured that the reference optical path and the measurement optical path remain parallel, thus ensuring the quality of the interference signal and the accuracy of the target focus position determination.

[0208] Optionally, before controlling the first adjustment mechanism to drive the interferometric scanning module to scan along the measurement optical path, the method further includes: controlling the second adjustment mechanism to adjust the reference objective and / or reference reflector so that the reference optical path is parallel to the measurement optical path.

[0209] Specifically, before controlling the first adjustment mechanism 20112 to drive the interferometric scanning module 20111 to scan along the measurement optical path, in order to ensure the parallelism between the reference optical path and the measurement optical path, the controller 20152 of the optical focusing system 201 also needs to control the second adjustment mechanism 20113 to adjust the reference objective lens 201112 and / or the reference mirror 201113.

[0210] As an example, the second adjustment mechanism 20113 is connected to the reference objective lens 201112, and the controller 20152 changes the direction of the reference light by adjusting the translation or rotation of the reference objective lens 201112, so that it is parallel to the measurement optical path.

[0211] As another example, the second adjustment mechanism 20113 is connected to the reference mirror 201113. By adjusting the attitude of the reference mirror 201113, the reflection direction of the reference light is changed, thereby achieving parallel calibration of the two beams.

[0212] As another example, the second adjustment mechanism 20113 is connected to the reference objective lens 201112 and the reference mirror 201113 simultaneously, and adjusts the two synchronously. Under the premise of ensuring that the reference mirror 201113 is located at the focal point of the reference objective lens 201112, the direction of the reference optical path is adjusted as a whole.

[0213] As can be seen in this embodiment, because the reference objective 201112 or reference mirror 201113 is calibrated before scanning and focusing, it can be ensured that the reference optical path and the measurement optical path are strictly parallel, thus ensuring the quality of the interference signal and the accuracy of the focus position determination.

[0214] S602: During the scanning process, the interference signal generated by the measurement signal light and the reference signal light is acquired.

[0215] Specifically, during the scanning process, the controller 20152 of the optical focusing system 201 synchronously collects the interference signals generated by the measurement signal light and the reference signal light through the interference signal collection module 2014. The interference signal collection module 2014 is set in the converging optical path formed by the convergence of the measurement signal light and the reference signal light. The focusing sensor 20142 inside it continuously collects the interference signals generated by the measurement signal light and the reference signal light at a preset sampling frequency and converts the optical signals into electrical signals for output.

[0216] S603: Determine the target focus position of the interferometric scanning module based on the interference signal.

[0217] Specifically, the controller 20152 of the optical focusing system 201 determines the target focusing position of the interferometric scanning module 20111 based on the acquired interferometric signal.

[0218] As an example, the controller 20152 first acquires the sequence data of the interference signal intensity changing with the scanning position, constructs the interference signal image, and then performs signal processing on the interference signal image, such as identifying the peak position of the interference envelope through an envelope extraction algorithm, or identifying the scanning coordinates corresponding to the zero optical path difference point through phase analysis, and determining the peak position or the coordinates corresponding to the zero optical path difference point as the target focusing position.

[0219] Optionally, before determining the target focus position of the interferometric scanning module based on the interferometric signal, the method further includes: determining the signal-to-noise ratio of the interferometric signal; if the signal-to-noise ratio of the interferometric signal is lower than a preset threshold, then performing the following operations: increasing the brightness of the light source; controlling the first adjustment mechanism again to drive the interferometric scanning module to scan along the measurement optical path; and during the scanning process, re-acquiring the interference signal generated by the measurement signal light and the reference signal light.

[0220] Specifically, before determining the target focus position of the interferometric scanning module 20111 based on the interferometric signal, the controller 20152 of the optical focusing system 201 needs to perform signal quality control on the interferometric signal and determine whether a rescan adjustment is required.

[0221] As an example, the controller 20152 first performs a signal-to-noise ratio evaluation on the acquired interference signal.

[0222] If the calculated signal-to-noise ratio is lower than the preset threshold, it indicates that the quality of the currently acquired interference signal is insufficient to support accurate target focus position identification, and the system will perform signal quality optimization operation.

[0223] The signal quality optimization operation specifically includes: increasing the brightness of the light source 2012; controlling the first adjustment mechanism 20112 again to drive the interference scanning module 20111 to scan along the measurement optical path; and during the scanning process, re-acquiring the interference signal generated by the measurement signal light and the reference signal light.

[0224] As can be seen in the embodiments of this application, by introducing a signal-to-noise ratio judgment and adaptive adjustment mechanism before determining the target focus position, the focus control method can effectively cope with signal quality fluctuations caused by factors such as sample reflectivity differences and environmental interference, thus ensuring that the interference signal used for focus position calculation has a sufficient signal-to-noise ratio, thereby improving the reliability and accuracy of focusing.

[0225] S604: Control the first adjustment mechanism to drive the interference scanning module to move to the target focusing position.

[0226] Specifically, the controller 20152 controls the first adjustment mechanism 20112 to drive the interferometric scanning module 20111 to move to the target focusing position. Specifically, the processor 20151 obtains the current actual position of the first adjustment mechanism 20112, calculates the positional deviation between the first adjustment mechanism 20112 and the target focusing position, calculates the driving direction and driving amount based on the deviation, and the controller 20152 controls the first adjustment mechanism 20112 to drive the interferometric scanning module 20111 to move along the optical axis until the target focusing position is reached.

[0227] For example, please refer to Figure 17 , Figure 17 This is a data flow diagram of a focus control method provided in an embodiment of this application, wherein the control processing unit 2015 includes a processor 20151 and a controller 20152, wherein: The processor 20151 includes a processing module 20153 and an analysis module 20154, and the controller 20152 includes a control module 20155. The processing module 20153 is used to receive the measurement signal light and reference signal light transmitted by the second relay mirror group 2019, and generate an interference signal based on the measurement signal light and reference signal light, and then send the interference signal to the analysis module 20154. The analysis module 20154 analyzes the interference signal to determine the target focus position of the target sample, and sends the target focus position to the control module 20155. The control module 20155 generates a control command based on the target focus position, and controls the first adjustment mechanism 20112 to move the interference scanning module 20111 to the target focus position based on the control command.

[0228] As can be seen, this focusing control method drives the interferometric scanning module 20111 to scan along the optical path, collects interference signals, analyzes and determines the target focusing position, and finally drives the module to move to that position, thus realizing closed-loop focusing control based on the interference principle. Because the interferometric scanning module 20111 has a light motion load and a fast scanning speed, the entire focusing process can be completed in a short time, significantly improving the response speed and overall efficiency of the optical focusing system 201.

[0229] Optionally, after controlling the first adjustment mechanism to drive the interferometric scanning module to move to the target focusing position, the method further includes: closing the variable aperture set in the reference optical path.

[0230] Specifically, after the first adjustment mechanism 20112 drives the interferometric scanning module 20111 to move to the target focusing position, the optical focusing system 201 also needs to close the variable aperture 20133 set in the reference optical path.

[0231] After the controller 20152 of the optical focusing system 201 completes the focusing operation, it sends a closing command to the variable aperture 20133. The variable aperture 20133 operates according to the command, blocking the reference optical path and preventing the reference light from continuing to be transmitted to the reference objective lens 201112 and the reference mirror 201113. At this time, only the measurement optical path remains open, and the measurement signal light is transmitted via the second relay lens group 2019 to the collection and detection module 20110 to generate measurement data for the target sample.

[0232] As can be seen, in this embodiment of the application, by turning off the variable aperture 20133 in the reference optical path after focusing is completed, the interference of the reference light on the subsequent measurement signal is effectively avoided. Therefore, the normal generation of interference signal during focusing is ensured, and the high signal-to-noise ratio of the signal during measurement is guaranteed, thus improving the stability of the overall measurement performance.

[0233] Optionally, after controlling the first adjustment mechanism to drive the interferometric scanning module to move to the target focusing position, the method further includes locking the first adjustment mechanism.

[0234] Specifically, after controlling the first adjustment mechanism 20112 to drive the interferometric scanning module 20111 to move to the target focusing position, the optical focusing system 201 also needs to lock the first adjustment mechanism 20112.

[0235] As an example, the first adjustment mechanism 20112 can be configured with a self-locking function, such as using a motor with a brake device. When the interferometric scanning module 20111 reaches the target focusing position, the optical focusing system 201 sends a locking command to the first adjustment mechanism 20112, activates the brake device, restricts the degree of freedom of movement of the first adjustment mechanism 20112, and keeps the interferometric scanning module 20111 at the target focusing position.

[0236] As can be seen in this embodiment, locking the first adjustment mechanism 20112 after focusing can effectively avoid the position drift of the interference scanning module caused by external vibration or movement of the stage, thus ensuring that the relative position between the objective lens and the sample remains stable during subsequent measurement, thereby ensuring the accuracy of the measurement data.

[0237] Optionally, after controlling the first adjustment mechanism to drive the interferometric scanning module to move to the target focusing position, the method further includes: controlling the motion stage carrying the target sample to move to the second measurement position, so that the second measurement point of the target sample is measured, and the second measurement position is located in the measurement plane; controlling the first adjustment mechanism to drive the interferometric scanning module to scan along the measurement optical path again.

[0238] Specifically, after the first adjustment mechanism 20112 drives the interferometric scanning module 20111 to move to the target focusing position, the controller 20152 of the optical focusing system 201 also controls the motion stage carrying the target sample to move to the second measurement position and performs the focusing scanning operation again to achieve the measurement of multiple measurement points of the target sample.

[0239] As an example, after the focusing operation of the first measurement point is completed, the optical focusing system 201 needs to continue measuring the second measurement point on the target sample. The optical focusing system 201 sends a movement command to the motion stage, driving the motion stage to move along a plane perpendicular to the measurement optical path, moving the second measurement point on the target sample directly below the measurement optical path, and aligning the second measurement position within the measurement plane with the optical axis of the measurement objective lens 201111. After the motion stage reaches the second measurement position and stabilizes, the optical focusing system 201 again controls the first adjustment mechanism 20112 to drive the interferometric scanning module 20111 to scan along the measurement optical path, acquire interference signals and determine the target focusing position of the second measurement point, and finally drives the interferometric scanning module 20111 to move to that position to complete focusing.

[0240] As can be seen from the embodiments of this application, by controlling the motion stage to move sequentially to different measurement positions and repeatedly performing focusing scans, this method realizes continuous focusing operations on multiple measurement points on the target sample, providing efficient focusing support for multi-point measurement.

[0241] It should be noted that, regarding the focusing control method implemented by the controller and processor in this application, those skilled in the art should understand that these control functions can be implemented in software, purely in hardware logic circuits, or in a combination of software and hardware. The mechanical structure for which protection is sought in this application does not depend on the choice of the above implementation method, but the specific implementation carrier of the control method can take different forms.

[0242] In one feasible implementation, the controller can be implemented in software, i.e., the processor reads and executes program instructions stored in memory to complete the functions corresponding to each control step. The processor can be any processing circuit with program instruction execution capability, including but not limited to: central processing unit (CPU), microprocessor (MCU), digital signal processor (DSP), programmable logic controller (PLC), embedded microcontroller, or a chip dedicated to motion control (such as a motion control coprocessor). The processor can exist as a single chip (such as a microcontroller) or be implemented as a system-on-a-chip (SoC). In this case, in addition to the processor core, the chip can also integrate some hardware acceleration circuits or dedicated peripheral interfaces (such as PWM output, quadrature encoder interface, CAN controller, etc.) for directly driving motors, cylinders, or other mechanical actuators.

[0243] In another feasible implementation, the controller can be implemented entirely in hardware, that is, the control logic is completed by hardware processing circuits that do not have program instruction execution capabilities. These hardware processing circuits can be built from discrete components (such as logic gates, flip-flops, and comparators), but to reduce size and improve reliability, they are typically implemented using integrated circuits, such as Application-Specific Integrated Circuits (ASICs) and Programmable Logic Devices (PLDs), including Field-Programmable Gate Arrays (FPGAs) and Complex Programmable Logic Devices (CPLDs). These hardware circuits can receive sensor signals from the mechanical system (such as limit switches, encoders, and force sensors), process them through combinational or sequential logic, and directly output drive signals (such as PWM waves and relay contact signals) to solenoid valves, servo drivers, or stepper motor drivers, thereby controlling the movement of the mechanical actuators.

[0244] This application does not limit all control functions to using the same implementation method. For example, the timing control part can be implemented using a PLC, while the high-speed response part can be implemented using pure hardware logic; or, one control module (such as position closed loop) can be implemented by an FPGA, and another control module (such as human-machine interaction) can be implemented by an MCU. Those skilled in the art can flexibly choose software, hardware, or a combination of both based on factors such as the real-time requirements, cost, and power consumption of the mechanical system. However, regardless of the implementation method used, as long as it implements the control method described in the claims of this application and can drive the corresponding mechanical structure to complete the predetermined action, it falls within the protection scope of this application.

[0245] The above description is merely a preferred embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. 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 scanning focusing device, applied to an optical focusing system, the optical focusing system comprising a light source, an interference beam splitting module, and an interference signal collection module, wherein the interference beam splitting module is disposed on the light-emitting side of the light source and is used to perform beam splitting processing on the illumination light provided by the light source to obtain a measurement light and a reference light, characterized in that, include: An interferometric scanning module and a first adjustment mechanism, wherein the first adjustment mechanism is connected to the interferometric scanning module; The interferometric scanning module includes a measurement objective lens, a reference objective lens, and a reference mirror, wherein: The measurement objective lens is disposed in the measurement optical path and is used to project the measurement light onto the surface of the target sample and receive the measurement signal light reflected back by the target sample. The reference objective lens is disposed in the reference optical path and is used to focus the reference light onto the reference mirror and receive the reference signal light reflected back by the reference mirror, wherein the reference optical path is parallel to the measurement optical path; The reference mirror is disposed at the end of the reference optical path and is used to reflect the reference light back to the reference objective lens; The first adjustment mechanism is used to drive the interferometric scanning module to scan along the measurement optical path and to drive the interferometric scanning module to move to the target focusing position. The target focusing position is determined by the interferometric signal collection module by acquiring the interference signal generated by the change of optical path difference between the measurement signal light and the reference signal light during the scanning process of the interferometric scanning module along the measurement optical path.

2. The scanning and focusing device according to claim 1, characterized in that, The scanning and focusing device further includes: a second adjustment mechanism. The second adjustment mechanism is connected to the reference objective lens, and the second adjustment mechanism is used to adjust the position and orientation of the reference objective lens; Alternatively, the second adjustment mechanism is connected to the reference mirror, and the second adjustment mechanism is used to adjust the position and orientation of the reference mirror; Alternatively, the second adjustment mechanism is connected to both the reference objective and the reference mirror, and the second adjustment mechanism is used to simultaneously adjust the pose of the reference objective and the reference mirror.

3. The scanning and focusing device according to claim 2, characterized in that, The second adjustment mechanism is connected to both the reference objective and the reference mirror. The scanning focusing device also includes a lens barrel, in which the reference objective and the reference mirror are installed. The second adjustment mechanism is connected to the lens barrel.

4. The scanning and focusing device according to claim 1, characterized in that, The measuring objective and the reference objective share the same objective type, and the measuring objective and the reference objective have the same numerical aperture.

5. An optical focusing system, characterized in that, Includes the scanning and focusing device as described in any one of claims 1-4; The system comprises an interferometric beam splitting module, an interferometric signal collection module, a processor, and a controller. The interferometric signal collection module is connected to the controller, and the controller is connected to the first adjustment mechanism. The interference beam splitting module is located on the light-emitting side of the light source and is used to split the externally provided illumination light to obtain the measurement light and the reference light. The interference signal collection module is disposed in the converging optical path and is used to collect the measurement signal light formed by the measurement light after being reflected by the target sample and the reference signal light formed by the reference light after being reflected by the target sample. The converging optical path is the path through which the measurement signal light and the reference signal light converge. The processor is used to determine the target focus position of the interferometric scanning module by the interference signal generated by the change of the optical path difference between the measurement signal light and the reference signal light; The controller is used to control the first adjustment mechanism to drive the interferometric scanning module to move to the target focusing position.

6. The optical focusing system according to claim 5, characterized in that, The interference beam splitting module includes: a first beam splitter and a first refracting mirror, wherein: The first beam splitter is disposed on the light-emitting side of the light source and is used to split the illumination light to obtain the measurement light and the reference light, and to transmit the measurement light to the measurement objective lens and the reference light to the refracting lens; The first refracting mirror is disposed in the reference optical path to deflect the reference light so that the deflected reference optical path is parallel to the measurement optical path, and to transmit the refracted reference light to the reference objective lens.

7. The optical focusing system according to claim 6, characterized in that, The system further includes: a third adjustment mechanism, which is connected to the first refracting mirror; The third adjustment mechanism is used to adjust the position and orientation of the first refracting mirror so that the reference optical path is parallel to the measurement optical path.

8. The optical focusing system according to claim 5, characterized in that, The interference signal collection module includes: a first relay mirror group and a focusing sensor; The first relay lens group is positioned in front of the focusing sensor to converge the measurement signal light and the reference signal light onto the focusing sensor. The focusing sensor is used to receive the measurement signal light and the reference signal light.

9. The optical focusing system according to claim 5, characterized in that, The interference beam splitting module also includes: a variable aperture; The variable aperture is disposed in the reference optical path, and the variable aperture is used to open or close the reference optical path.

10. The optical focusing system according to claim 5, characterized in that, The optical focusing system further includes: an illumination modulation module; The illumination modulation module is disposed between the light source and the interference beam splitting module, and is used to modulate the illumination light.

11. The optical focusing system according to any one of claims 5-10, characterized in that, The optical focusing system also includes: a second relay lens group and a collection and detection module; The second relay mirror group is disposed on the light-incident side of the collection and detection module, and is used to transmit the measurement signal light and the reference signal light to the interference signal collection module before the interference scanning module moves to the target focusing position; and to transmit the measurement signal light to the collection and detection module after the interference scanning module moves to the target focusing position. The collection and detection module is located at the end of the measurement optical path and is used to collect the measurement signal light and generate measurement data of the target sample based on the measurement signal light.

12. A semiconductor device, characterized in that, include: The optical focusing system as described in any one of claims 5-11.

13. A focusing control method, applied to the optical focusing system as described in any one of claims 5-11, characterized in that, The method includes: The first adjustment mechanism is controlled to drive the interference scanning module to scan along the measurement optical path; During the scanning process, the interference signal generated by the measurement signal light and the reference signal light is acquired; The target focus position of the interferometric scanning module is determined based on the interference signal; The first adjustment mechanism is controlled to drive the interferometric scanning module to move to the target focusing position.

14. The method according to claim 13, characterized in that, After the first adjustment mechanism drives the interferometric scanning module to move to the target focusing position, the method further includes: Close the variable aperture set in the reference optical path.

15. The method according to claim 13, characterized in that, Before controlling the first adjustment mechanism to drive the interferometric scanning module to scan along the measurement optical path, the method further includes: The third adjustment mechanism is controlled to adjust the orientation of the refracting mirror so that the reference optical path is parallel to the measurement optical path; or, The second adjustment mechanism is controlled to adjust the reference objective and / or the reference reflector so that the reference optical path is parallel to the measurement optical path.

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