Focusing and leveling device and semiconductor apparatus

Abstract

The embodiment of the present application relates to the technical field of semiconductor, and specifically discloses a focusing and leveling device and a semiconductor device, the focusing and leveling device comprising: a light source for emitting a detection light beam; a light beam stabilizing device arranged on an exit light path of the light source, the light beam stabilizing device being used for detecting position information and pointing information of the detection light beam, and adjusting a transmission direction of the detection light beam according to a deviation of the position information and the pointing information from preset reference information, so that the detection light beam emitted by the light beam stabilizing device remains stable; and a measuring device arranged on an exit light path of the light beam stabilizing device, the measuring device being used for receiving the detection light beam which is stably adjusted by the light beam stabilizing device, projecting the detection light beam to a surface of a device to be measured, and receiving a feedback light beam reflected by the surface of the device to be measured to determine height information of the surface of the device to be measured.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and in particular to a focusing and leveling device and a semiconductor device. Background Technology

[0002] In photolithography equipment, focusing and leveling devices are used to measure the height and tilt of the wafer surface to ensure that the wafer remains within the depth of focus of the projection lens during exposure. These focusing and leveling devices typically employ the principle of optical triangulation, where a light beam is emitted from a light source and projected onto the wafer surface. The reflected beam is then received, and the wafer's height is calculated based on changes in the position or intensity of the reflected beam. This measurement method relies on the stability of the light beam incident on the wafer surface.

[0003] In practical applications, the light source itself exhibits both pointing and positional shifts. When the light source's pointing direction shifts, the angle of the beam incident on the wafer surface changes, causing a shift in the position of the beam spot on the wafer surface. Similarly, when the light source's position shifts, the entire beam incident on the wafer surface is translated, also causing a shift in the beam spot position. Both of these shifts alter the path of the reflected beam, which is compounded by the change in the reflected beam path caused by variations in wafer height.

[0004] Because the frequency of the light source offset is high, the Z-axis motion mechanism supporting the wafer cannot compensate for this high-frequency change. Therefore, the focusing and leveling device cannot distinguish whether the change in the reflected beam is caused by the change in wafer height or by the offset of the light source, thus generating measurement errors. Summary of the Invention

[0005] This application discloses a focusing and leveling device and a semiconductor device, which aim to reduce the impact of pointing and positional offsets of the probe light source on the measurement accuracy of the focusing and leveling device.

[0006] In a first aspect, this application provides a focusing and leveling device, comprising: a light source for emitting a probe beam; a beam stabilizing device disposed on the output optical path of the light source, the beam stabilizing device being used to detect the position information and pointing information of the probe beam, and to adjust the transmission direction of the probe beam according to the deviation between the position information and pointing information and preset reference information, so as to keep the probe beam emitted by the beam stabilizing device stable; and a measuring device disposed on the output optical path of the beam stabilizing device, the measuring device being used to receive the probe beam stabilized by the beam stabilizing device, and to project the probe beam onto the surface of a device under test, and to receive a feedback beam reflected by the surface of the device under test to determine the height information of the surface of the device under test.

[0007] In one possible implementation, the beam stabilization device includes: a beam splitting adjustment component disposed on the outgoing light path of the light source, the beam splitting adjustment component being used to adjust the transmission direction of the probe beam and split the probe beam into a first beam and a second beam; a detection component being used to receive the first beam and obtain the position information and pointing information of the probe beam based on the first beam, the second beam being used to enter the measuring device; and a control component being electrically connected to the detection component and the beam splitting adjustment component respectively, being used to control the beam splitting adjustment component to compensate for the transmission direction of the probe beam based on the deviation between the position information and pointing information detected by the detection component and preset reference information.

[0008] In one possible implementation, the beam splitting adjustment assembly includes: an adjustment element disposed on the outgoing light path of the light source for adjusting the transmission direction of the detection beam in a first direction; and a first beam splitting element disposed on the outgoing light path of the adjustment element, wherein the first beam splitting element is used to adjust the transmission direction of the detection beam in a second direction and split the detection beam into a first beam and a second beam; wherein the first beam is a transmitted beam and is used to incident on the detection assembly, and the second beam is a reflected beam and is used to incident on the measuring device.

[0009] In one possible implementation, the detection component includes: a second beam splitter disposed on the transmission path of the first beam splitter, the second beam splitter splitting the first beam into a transmission sub-beam and a reflection sub-beam; a first detection unit for receiving the transmission sub-beam to obtain the position information of the detection beam; and a second detection unit for receiving the reflection sub-beam to obtain the pointing information of the detection beam.

[0010] In one possible implementation, the first detection unit includes: a first photodetector disposed in the transmission optical path of the second beam splitter, wherein the first photodetector is a quadrant detector or a position-sensitive detector.

[0011] In one possible implementation, the second detection unit includes: a first focusing element disposed in the reflected light path of the beam splitter; and a second photodetector disposed in the emitted light path of the first focusing element to obtain the pointing information of the detection beam.

[0012] In one possible implementation, the beam stabilization device keeps the maximum angular deviation of the probe beam below a preset threshold, so that the maximum offset range of the probe beam on the surface of the device under test is less than the measurement error of the focusing and leveling device.

[0013] In one possible implementation, the preset threshold is 0.1°.

[0014] In one possible implementation, the measuring device comprises: a projection component disposed in the output optical path of the beam stabilization device for projecting the stabilized probe beam onto the surface of the device under test, wherein the magnification of the projection component is adjustable to adjust the measurement range of the focusing and leveling device; a detection component for receiving the feedback beam reflected from the surface of the device under test and converting it into an electrical signal; and a processor electrically connected to the detection component for processing the electrical signal to determine the height information of the surface of the device under test.

[0015] In one possible implementation, the projection component includes: a projection grating disposed on the outgoing light path of the beam stabilization device; and a projection optical unit disposed on the outgoing light path of the projection grating, wherein the projection optical unit is used to change the magnification of the projection component; wherein the measurement range of the focusing and leveling device is proportional to the grating period of the projection grating and inversely proportional to the incident angle of the probe beam onto the surface of the device under test and the magnification of the projection optical unit.

[0016] In one possible implementation, the projection grating is a transmissive grating, comprising periodically arranged transparent and non-transmissive regions.

[0017] In one possible implementation, the grating period of the projection grating is from 8 μm to 200 μm.

[0018] In one possible implementation, the projection grating is used to divide the probe beam into multiple sub-beams; the projection optical unit is used to adjust the main rays of the multiple sub-beams to be parallel to the optical axis of the projection optical unit on both the incident and exit sides, and then project the multiple sub-beams onto the surface of the device under test.

[0019] In one possible implementation, the projection optical unit includes: a first lens group disposed in the outgoing light path of the projection grating; and a second lens group disposed in the outgoing light path of the first lens group, wherein the distance between the second lens group and the first lens group is adjustable to change the magnification of the projection component.

[0020] In one possible implementation, the first lens group is used to make the principal ray of the sub-beam parallel to the optical axis on the incident side of the projection optical unit, and the second lens group is used to make the principal ray of the sub-beam parallel to the optical axis on the exit side of the projection optical unit.

[0021] In one possible implementation, the detection component includes: a detection grating disposed on the propagation path of the feedback beam for receiving the feedback beam and forming moiré fringes; A polarization beam splitter is disposed on the output optical path of the probe grating to separate the moiré fringes into polarized beams with at least two different polarization directions. A detector array is disposed on the output optical path of the polarization beam splitter, the detector array including at least two detectors to receive the polarized beams with at least two different polarization directions and convert them into corresponding electrical signals, so that the processor can perform differential processing on the electrical signals to determine the height information of the surface of the device under test.

[0022] In one possible implementation, the detector array is a quadrant detector, which includes a first detector and a second detector, the first detector and the second detector being located in the left half and right half of the detector array, respectively. The first detector is used to receive the first polarized light in the polarized beam and convert it into a first electrical signal. The second detector is used to receive the second polarized light in the polarized beam and convert it into a second electrical signal. The processor performs differential processing on the first electrical signal and the second electrical signal to determine the height information of the surface of the device under test.

[0023] In one possible implementation, the detection component further includes: a second focusing element disposed on the outgoing optical path of the polarization beam splitter for converging the first polarized light and the second polarized light emitted from the polarization beam splitter; and a filtering element disposed on the outgoing optical path of the second focusing element for filtering the converged first polarized light and the second polarized light to filter out stray light and select a beam of a preset wavelength to guide into the detector array.

[0024] In one possible implementation, the defocusing amount of the device under test is linearly related to the differential electrical signal, which is the differential signal between the first electrical signal and the second electrical signal. The preset range is the linear region within one cycle of the differential electrical signal.

[0025] In one possible implementation, the detection component further includes: a detection imaging element disposed between the detection grating and the device under test, for receiving the feedback beam and imaging the feedback beam onto the detection grating.

[0026] Secondly, embodiments of this application also provide a semiconductor device, including: a focusing and leveling device provided in any embodiment of the first aspect of this application.

[0027] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the optical path structure of a focusing and leveling device provided in an embodiment of this application; Figure 2 This is a schematic diagram of the optical path structure of the detection device in a focusing and leveling device provided in an embodiment of this application; Figure 3 A diagram showing the correspondence between the projection grating and the detection grating in a focusing and leveling device provided in this application embodiment; Figure 4 This application provides an embodiment of a focusing and leveling device that includes a projection grating, a probe grating, and a moiré fringe formation process. Figure 4 (a) in the diagram is a schematic diagram of a projection grating. Figure 4 (b) in the diagram is a schematic diagram of the detection grating. Figure 4 (c) in the diagram is a schematic diagram of the reflected grating image. Figure 4 (d) in the diagram is a schematic of moiré fringes; Figure 5 A detection area diagram of a detector array in a focusing and leveling device provided in an embodiment of this application; Figure 6 This application provides a defocus response curve diagram of different polarization state electrical signals and differential electrical signals in a focusing and leveling device as a function of defocus amount; Figure 7 A linear relationship diagram between the electrical signal output by the detector array and the defocus amount in a focusing and leveling device provided in this application embodiment.

[0030] Explanation of reference numerals in the attached figures: 1-Focusing and leveling device; 10 - Light source; 101 - First reflecting mirror; 102 - Second reflecting mirror; 20-Beam stabilization device; 201-Spectroscopy adjustment assembly; 2011-Adjustment element; 2012-First spectroscopy element; 202-Detection assembly; 2021-Second spectroscopy element; 2022-First detection unit; 20221-First photodetector; 2023-Second detection unit; 20231-First focusing element; 20232-Second photodetector; 203-Control assembly; 204-Acquisition element; 30-Measuring device; 301-Projection assembly; 3011-Projection grating; 3011a-First non-transparent area; 3011b-First transparent area; 3012-Projection optical unit; 302-Detection assembly; 3021-Detection grating; 3021a-Second non-transparent area; 3021b-Second transparent area; 3022-Polarization beam splitter; 3023-Detector array; 3023a-Left half-region; 3023b-Right half-region; 3024-Detection imaging element; 3025-Second focusing element; 3026-Filter element; 303-Processor; 304-Third reflector; 305-Fourth reflector; 100 - Device under test; 2-Workpiece stage control system; 3-Drive components. Detailed Implementation

[0031] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0032] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, component, or part to having a specific orientation, or to be constructed and operated in a specific orientation.

[0033] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0034] Furthermore, the terms "installation," "setup," "equipped with," "connection," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or constituent parts. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0035] Furthermore, the terms "first," "second," etc., are primarily used to distinguish different devices, components, or constituent parts (which may be the same or different in specific type and construction), and are not intended to indicate or imply the relative importance or quantity of the indicated devices, components, or constituent parts. Unless otherwise stated, "a plurality of" means two or more.

[0036] This embodiment provides a focusing and leveling device 1, such as... Figure 1 As shown, it includes a light source 10, a beam stabilization device 20, and a measuring device 30.

[0037] The light source 10 can be a coherent light source 10, used to emit a probe beam. In this embodiment, the light source 10 can be an ultraviolet light source, a visible light source, or an infrared light source, which can be selected according to the material of the device under test 100 and the measurement accuracy requirements. For example, when the surface of the device under test 100 is coated with photoresist, a light source with a wavelength far from the photosensitive band of the photoresist can be selected to avoid interference with the exposure process. The device under test 100 can be a semiconductor wafer.

[0038] like Figure 1 As shown, the light beam emitted by the light source 10 can be reflected by the first reflector 101 and the second reflector 102 and then enter the beam stabilizing device 20 to meet the requirements of the optical path structure.

[0039] When the light source 10 emits a probe beam, it may exhibit minute fluctuations in position and direction. These fluctuations are typically high-frequency and difficult to completely eliminate through subsequent signal processing. If such a fluctuating probe beam is used directly for measurement, the energy of the fluctuations will be superimposed on the measurement signal, causing measurement errors. In this embodiment, the beam stabilization device 20 actively adjusts the probe beam between the light source 10 and the measuring device 30, ensuring that the probe beam entering the measuring device 30 remains stable.

[0040] A beam stabilization device 20 is disposed in the output light path of the light source 10. After the light source 10 emits a probe beam, the beam stabilization device 20 detects and adjusts the probe beam.

[0041] Specifically, the beam stabilization device 20 can detect the position and pointing information of the probe beam. The position information reflects the lateral positional offset of the probe beam in a plane perpendicular to the transmission direction. The pointing information reflects the angular offset of the probe beam's transmission direction. These two types of information together reflect the stability state of the beam.

[0042] The beam stabilization device 20 compares the detected position and pointing information with preset reference information. The preset reference information can be the position and pointing parameters of a pre-calibrated ideal beam. When the detected position or pointing information deviates from the preset reference information, the beam stabilization device 20 can adjust the transmission direction of the probe beam according to the deviation amount, so that the position and pointing information of the probe beam are restored to a state close to the reference.

[0043] In addition to its detection function, the beam stabilization device 20 also has an adjustment function, thereby performing dual adjustment of the positional and angular offsets of the probe beam emitted from the light source 10. This is because both the positional and angular offsets of the probe beam affect the final spot position on the surface of the device under test 100. If only one is adjusted, the other offset will still lead to the final measurement error. By performing dual detection and dual adjustment of these two offsets, the stability of the beam can be maintained more comprehensively. Through the detection and adjustment process of the beam stabilization device 20, the probe beam is kept relatively stable, and the offset of the probe beam in the lateral position and the change in the angular direction of the probe beam are suppressed simultaneously.

[0044] In one implementation, the beam stabilization device 20 can be a closed-loop feedback control structure. The beam stabilization device 20 may include a detection unit for acquiring the position information (lateral position offset) and pointing information (angular pointing offset) of the probe beam. The detection unit transmits the acquired signals to the control unit, which compares the detected signals with a preset reference signal to calculate the position deviation and pointing deviation. Based on the calculation results, the control unit drives the execution component to change the transmission direction of the probe beam, restoring the position and pointing of the probe beam to the reference state.

[0045] In another implementation, the beam stabilization device 20 can be a control structure combining feedforward and feedback. The beam stabilization device 20 may include a monitoring unit, a correction unit, and a control unit. The monitoring unit is located on the output optical path of the light source 10 and is used to acquire the initial state parameters of the probe beam in real time, including the beam's lateral position and angular direction. The correction unit is located on the output optical path of the monitoring unit and is used to adjust the transmission direction of the probe beam. When the monitoring unit detects a change in the state parameters of the probe beam, it transmits the change to the control unit. The control unit calculates the correction amount according to a preset compensation algorithm and drives the correction unit to perform angle compensation in advance, so that the fluctuation of the output beam is suppressed within a preset range. Simultaneously, the beam stabilization device 20 can also have a feedback detection unit at the output end, feeding back the actual state parameters of the output beam to the control unit for comparison with a preset benchmark, correcting the compensation amount of the correction unit, thus forming a control structure combining feedforward and feedback.

[0046] The measuring device 30 is positioned on the output optical path of the beam stabilizing device 20. The probe beam, stabilized by the beam stabilizing device 20, enters the measuring device 30.

[0047] The measuring device 30 projects the received probe beam onto the surface of the device under test 100. The device under test 100 can be a semiconductor wafer or other substrate that requires surface height detection. The probe beam is reflected on the surface of the device under test 100, forming a feedback beam. The feedback beam carries the height information of the surface of the device under test 100. When the height of the surface of the device under test 100 changes, the path of the reflected beam also changes accordingly.

[0048] The measuring device 30 receives a feedback beam reflected from the surface of the device under test (DUT) 100 and determines the height information of the DUT 100 surface based on the feedback beam. Specifically, the measuring device 30 can calculate the defocusing amount of the DUT 100 surface by analyzing the positional changes, intensity changes, or phase changes of the feedback beam on the detection surface. The defocusing amount can be understood as the distance offset of the DUT 100 surface relative to the imaging focal plane of the measuring device 30, and is used to characterize the deviation between the current position of the DUT 100 and the ideal exposure position.

[0049] In one implementation, the measuring device 30 can be implemented using the principle of triangulation. The measuring device 30 projects a probe beam at a certain angle onto the surface of the device under test (DUT) 100, forming a measuring spot on the surface of DUT 100. When the height of the surface of DUT 100 changes, the position of the measuring spot moves accordingly, and the emission direction of the reflected beam also changes accordingly. By detecting the change in the position of the reflected beam on the probe surface, the measuring device 30 establishes a correspondence between the position of the reflected spot and the height of the surface of DUT 100, thereby calculating the height information of the surface of DUT 100.

[0050] In another implementation, the measuring device 30 can be implemented using the principle of interferometry. The measuring device 30 splits the probe beam into a structured beam and projects it onto the surface of the device under test (DUT) 100. The beam reflected from the surface of DUT 100 interferes with the reference beam, forming interference fringes. The phase distribution of the interference fringes changes with the height of the surface of DUT 100. By acquiring image information of the interference fringes and analyzing the phase changes, the measuring device 30 calculates the height information of the surface of DUT 100.

[0051] It is worth noting that, compared with related technical solutions that passively compensate for signals with mixed errors within the measurement optical path, the beam stabilization device 20 in the focusing and leveling device 1 provided in this application embodiment can actively detect and correct the positional and angular offsets generated by the light source 10 itself, isolating light source fluctuations from the source outside the measurement path. Regardless of whether the light source 10 itself has fluctuations, the probe beam entering the measuring device 30 remains highly stable. Thus, the feedback beam change received by the measuring device 30 mainly originates from the actual height change of the surface of the device under test 100, rather than light source noise, converting passive compensation into active isolation, thereby improving the reliability of the measurement results of the focusing and leveling device 1 from the source. Furthermore, the beam stabilization device 20 provided in this application embodiment can simultaneously detect and adjust the positional and angular offsets of the probe beam, and can achieve closed-loop dynamic stabilization using feedback or feedforward control, thereby maintaining measurement accuracy.

[0052] Thus, the focusing and leveling device 1 provided in this application embodiment achieves pre-emptive active stabilization of the probe beam by introducing a beam stabilization device 20 between the light source 10 and the measuring device 30. Before measurement, the beam is stabilized, and the beam stabilization device 20 isolates the inherent fluctuations of the probe beam generated by the light source 10 from the measurement path. Regardless of whether the light source 10 itself has any offset, the beam entering the measuring device 30 is in a relatively stable state. In this way, the change in the feedback beam received by the measuring device 30 mainly originates from the height change of the surface of the device under test 100, rather than the fluctuations of the light source 10, thereby improving the reliability of the measurement results of the focusing and leveling device 1.

[0053] In some embodiments, the beam stabilization device 20 includes a beam splitting adjustment component 201. The beam splitting adjustment component 201 is disposed in the outgoing light path of the light source 10. The beam splitting adjustment component 201 can be used to adjust the transmission direction of the probe beam, and can also split the probe beam into a first beam and a second beam.

[0054] The beam splitting adjustment assembly 201 is disposed in the output optical path of the light source 10 and may include two moving mirrors. The first moving mirror is used to adjust the transmission direction of the probe beam in the X direction, and the second moving mirror is disposed in the output optical path of the first moving mirror and is used to adjust the transmission direction of the probe beam in the Y direction.

[0055] By setting two moving galvanometers, the transmission direction of the probe beam in the X and Y directions can be adjusted independently, achieving two-dimensional adjustment of the beam direction. The adjustments in the two directions do not interfere with each other. The control device within the focusing and leveling device 1 can calculate the deviation in the X and Y directions based on the position and pointing information fed back by the detection component 202, and accordingly drive the two moving galvanometers to compensate. In this way, regardless of which direction the pointing deviation of the light source 10 occurs, it can be detected and compensated independently, keeping the probe beam stable in both directions and providing a stable incident beam for the subsequent measuring device 30.

[0056] The surface of the second moving galvanometer may be provided with a beam-splitting film to split the incident probe beam into a transmitted first beam and a reflected second beam. The first beam is used for position and direction detection, and the second beam is used for subsequent measurement. After receiving the second beam, the measuring device 30 projects it onto the surface of the device under test 100 and determines the height of the surface of the device under test 100 based on the reflected feedback beam.

[0057] It is worth noting that since the first and second beams are regulated by the same beam splitting adjustment component 201, when the beam splitting adjustment component 201 adjusts the transmission direction of the probe beam, the first and second beams after beam splitting the probe beam are also adjusted synchronously. Therefore, the position and pointing information obtained by the detection component 202 from the first beam can reflect the true state of the second beam incident into the measuring device 30. When the control component 203 controls the beam splitting adjustment component 201 to adjust the probe beam according to the detection result of the first beam, the transmission direction of the second beam is also corrected synchronously. In this way, the second beam incident on the measuring device 30 is no longer affected by the pointing and positional offset of the light source 10 itself, and the second beam received by the measuring device 30 is in a relatively stable state.

[0058] In some embodiments, the beam stabilization device 20 includes a detection component 202. The detection component 202 is disposed in the transmission optical path of the beam splitting adjustment component 201 and is used to receive the first beam. The detection component 202 simultaneously acquires the position information and pointing information of the detection beam based on the first beam.

[0059] In one embodiment, the detection assembly 202 may include a beam splitter, a focusing lens, and two photodetectors. After the first light beam is incident on the beam splitter, a portion of the light passes through the beam splitter and directly into the first photodetector, which outputs an electrical signal corresponding to the lateral position of the light beam. The other portion of the light is reflected by the beam splitter and then converged by the focusing lens to the second photodetector, which outputs an electrical signal corresponding to the angular direction of the light beam. The output signals of the two photodetectors together reflect the position and direction information of the detected light beam.

[0060] In another embodiment, the detection component 202 may include two position-sensitive detectors and a beam splitter. The first beam, after being incident on the beam splitter, is split into two paths. One path directly incidents on the first position-sensitive detector to detect the beam's position information; the other path is converged by a focusing lens and then incident on the second position-sensitive detector to detect the beam's angle information. The two position-sensitive detectors output electrical signals corresponding to the beam information and pointing information, respectively.

[0061] In some embodiments, the beam stabilization device 20 includes a control component 203. The control component 203 is electrically connected to the detection component 202 and the beam splitting adjustment component 201, respectively. The control component 203 receives the position information and pointing information output by the detection component 202, compares the detected information with preset reference information, calculates the position deviation and pointing deviation, and drives the two moving mirrors in the beam splitting adjustment component 201 to perform closed-loop adjustment and correction of the transmission direction of the probe beam, so that the first beam and the second beam emitted from the beam splitting adjustment component 201 are synchronously restored to the preset reference state, thereby providing a continuous and reliable probe light for subsequent measurement.

[0062] In some embodiments, the beam-splitting adjustment assembly 201 includes an adjustment element 2011. The adjustment element 2011 is disposed in the outgoing light path of the light source 10 and is used to adjust the transmission direction of the probe beam in a first direction. The adjustment element 2011 can be the aforementioned first moving mirror or a reflector driven by piezoelectric ceramic. By changing the reflection angle of the moving mirror, the transmission direction of the probe beam in the X direction is changed.

[0063] In some embodiments, the beam splitting adjustment assembly 201 includes a first beam splitting element 2012. The first beam splitting element 2012 may be the second moving mirror described above. The first beam splitting element 2012 is disposed in the output optical path of the adjustment element 2011 and is used to adjust the transmission direction of the probe beam in the Y direction and split the probe beam into a first beam and a second beam.

[0064] In one implementation, the first beam-splitting element 2012 can be a moving beam-splitting prism. The moving beam-splitting prism may contain a beam-splitting film. When the probe beam is incident, part of the light passes through the beam-splitting film to form a first beam, and the other part is reflected by the beam-splitting film to form a second beam. The moving beam-splitting prism as a whole can be driven to rotate, thereby adjusting the transmission direction of the second beam while splitting the light.

[0065] In another implementation, the first beam-splitting element 2012 may include a combination of a prism and a mirror. The prism is used for beam splitting, and the mirror is used to adjust the transmission direction of the probe beam in the Y direction.

[0066] In this way, the first beam splitter 2012 can both change the transmission direction of the probe beam in the Y direction and split the incident probe beam into a transmitted first beam and a reflected second beam. The first beam is a transmitted beam, used to be incident on the detection component 202 for detecting position and orientation information. The second beam is a reflected beam, used to be incident on the measuring device 30 for measuring the height of the device under test 100.

[0067] When the angle of the adjusting element 2011 or the first beam splitter 2012 changes, the transmission direction of the probe beam changes accordingly, and the states of the first and second beams also change synchronously. Through the cooperation of the adjusting element 2011 and the first beam splitter 2012, two-dimensional adjustment of the probe beam in the X and Y directions can be achieved. Simultaneously, the probe beam is split, ensuring that the first and second beams have consistent sources, thus meeting the dual requirements of subsequent detection and measurement.

[0068] In some embodiments, the detection component 202 includes a second beam splitter 2021. The second beam splitter 2021 is disposed in the transmission light path of the first beam splitter 2012 and is used to split the first beam into a transmission sub-beam and a reflection sub-beam.

[0069] By placing the second beam splitter 2021 on the light-emitting side of the first beam splitter 2012, two independent sub-beams can be split from the first beam without obstructing its original path. These sub-beams are used for position information detection and direction information detection, respectively. The two sub-beams are spatially separated after exiting the second beam splitter 2021, without interfering with each other. This results in a simpler overall optical path structure and more flexible component layout.

[0070] The second beam splitter 2021 is the same as the first beam splitter 2012 and may include a moving beam splitter prism. The moving beam splitter prism has a beam splitting film inside. When the first beam is incident, part of the light passes through the beam splitting film to form a transmissive sub-beam, and the other part of the light is reflected by the beam splitting film to form a reflective sub-beam. Alternatively, the second beam splitter 2021 may be a combination structure of a prism and a reflector, which will not be described in detail here.

[0071] In some embodiments, the detection component 202 includes a first detection unit 2022. The first detection unit 2022 is disposed in the transmission optical path of the second beam splitter 2021 and is used to receive the transmitted sub-beam.

[0072] The first detection unit 2022 may include a photodetector, which outputs an electrical signal corresponding to the position of the light spot of the transmissive beam. This electrical signal reflects the lateral positional offset of the detection beam, i.e., position information.

[0073] In some embodiments, the detection component 202 includes a second detection unit 2023. The second detection unit 2023 is disposed on the reflected light path of the second beam splitter 2021 and is used to receive the reflected sub-beam. The second detection unit 2023 may include a photodetector, which outputs an electrical signal corresponding to the position of the converging light spot. This electrical signal reflects the angular pointing offset of the detection beam, i.e., pointing information.

[0074] The first beam is split into a transmitted sub-beam and a reflected sub-beam by the second beam splitter 2021, which are received by the first detection unit 2022 and the second detection unit 2023, respectively. This enables parallel detection of the position and direction information of the probe beam. The change in the spot position of the transmitted sub-beam mainly reflects the lateral position offset of the probe beam, while the reflected sub-beam mainly reflects the angular direction offset of the probe beam. The two detections do not interfere with each other and can be performed simultaneously. Since the transmitted and reflected sub-beams originate from the same first beam, their state information is synchronized. Therefore, the control component 203 can simultaneously acquire the position and direction deviations of the probe beam without the need for time-division multiplexing or calculation through other methods.

[0075] Thus, when the probe beam exhibits both positional and angular deviations, the detection component 202 can output corresponding electrical signals. The processor 303 within the focusing and leveling device 1 calculates the positional and pointing deviations accordingly and controls the control component 203 to drive the adjustment element 2011 and the first beam-splitting element 2012 in the beam-splitting adjustment component 201 for compensation. Compared to schemes that only detect one type of deviation, the focusing and leveling device 1 provided in this embodiment can acquire more comprehensive state information of the probe beam, resulting in higher stability of the compensated beam.

[0076] In some embodiments, the first detection unit 2022 is used to receive the transmitted sub-beam to obtain the position information of the probe beam. The first detection unit 2022 includes a first photodetector 20221, which is disposed on the transmitted light path of the second beam splitter 2021.

[0077] The first photodetector 20221 can be a quadrant detector. A quadrant detector consists of four independent photosensitive regions. When a transmitted sub-beam is incident on the quadrant detector, the intensity of the electrical signal output from each of the four regions is related to the distribution ratio of the light spot in each region. When the probe beam undergoes a lateral shift, the position of the light spot of the transmitted sub-beam moves accordingly, and the signal ratios output from the four regions change. Based on the difference in signals from each region, the lateral shift of the light spot can be calculated, thus obtaining the position information of the probe beam.

[0078] The first photodetector 20221 can also be a position-sensitive detector. A position-sensitive detector is a continuous-type photodetector. When the transmitted beam is incident on the detector surface, the detector outputs an electrical signal corresponding to the centroid position of the beam. When the probe beam undergoes a lateral shift, the centroid position of the beam moves, and the electrical signal output by the detector changes accordingly. The lateral shift of the probe beam can be directly obtained from the signal change, thus providing the position information of the probe beam.

[0079] In some embodiments, the second detection unit 2023 includes a first focusing element 20231 and a second photodetector 20232.

[0080] The first focusing element 20231 is disposed in the reflected light path of the second beam splitter 2021 to converge the reflected sub-beam. After the reflected sub-beam emitted from the second beam splitter 2021 is incident on the first focusing element 20231, the beam is compressed and converged into a smaller spot. When the angle of the probe beam changes, the transmission direction of the reflected sub-beam changes accordingly, and the position of the spot converged by the first focusing element 20231 will also shift accordingly.

[0081] The second photodetector 20232 is disposed in the outgoing light path of the first focusing element 20231 and is used to receive the light spot converged by the first focusing element 20231. The second photodetector 20232 can be a quadrant detector or a position-sensitive detector. According to the optical conversion principle, the change in the angular direction of the probe beam is converted into a change in the position of the converged light spot on the surface of the second photodetector 20232 after passing through the first focusing element 20231. The second photodetector 20232 detects this position change and outputs a corresponding electrical signal, which reflects the angular direction shift of the probe beam.

[0082] By focusing the reflector beam into a small spot using the first focusing element 20231, the sensitivity of the second photodetector 20232 to changes in the spot's position can be improved. When the angle of the detection beam changes slightly, the displacement of the focused spot on the detector surface is amplified, resulting in a more noticeable change in the electrical signal output by the second photodetector 20232, which helps improve the detection accuracy of the pointing information. Simultaneously, the smaller size of the focused spot matches the photosensitive surface size of high-precision detectors, reducing stray light interference.

[0083] In some embodiments, the beam stabilization device 20 includes a collection element 204. The collection element 204 is connected to the first photodetector 20221 and the second photodetector 20232, and transmits the data collected by the first photodetector 20221 and the second photodetector 20232 to the processor 303.

[0084] In some embodiments, such as Figure 1 As shown, the measuring device 30 includes a projection component 301. The projection component 301 is disposed in the output optical path of the beam stabilizing device 20 and is used to project the stabilized probe beam onto the surface of the device under test 100. Specifically, the second beam formed after being split by the first beam splitter 2012, i.e., the projection component 301 is disposed in the reflected optical path of the first beam splitter 2012, and the second beam reflected by the first beam splitter 2012 is incident on the projection component 301.

[0085] The magnification of the projection component 301 is adjustable, and the measurement range of the focusing and leveling device 1 can be adjusted by changing the magnification.

[0086] In one implementation, the projection assembly 301 includes a projection grating 3011 and a projection optics unit 3012. The projection grating 3011 splits the probe beam into multiple sub-beams, and the projection optics unit 3012 projects these sub-beams onto the surface of the device under test 100. The projection optics unit 3012 may include a zoom lens group, and the magnification is adjusted by changing the spacing between the lenses in the lens group.

[0087] In another implementation, the projection assembly 301 includes an adjustable beam expander and a projection objective. The adjustable beam expander is disposed in the output optical path of the beam stabilization device 20 and is used to change the beam diameter of the probe beam. The projection objective projects the expanded beam onto the surface of the device under test 100.

[0088] The magnification of the projection component 301 corresponds to the measurement range of the focusing and leveling device 1. When the magnification increases, the spacing between the sub-beams projected onto the surface of the device under test 100 increases, and the positional change of the reflected beam caused by the change in the height of the device under test 100 becomes more obvious, thus improving the measurement sensitivity, but reducing the measurable height range. When the magnification decreases, the spacing between the sub-beams projected onto the surface of the device under test 100 decreases, increasing the measurable height range, but correspondingly reducing the measurement sensitivity.

[0089] By adjusting the magnification of the projection component 301, an appropriate measurement range can be selected based on the surface undulation of the device under test 100: for a relatively flat device under test 100, the projection component 301 can be adjusted to a larger magnification to obtain higher measurement accuracy; for a device under test 100 with a large surface undulation, the projection component 301 can be adjusted to a smaller magnification to ensure that the measurement range covers the entire undulating area of ​​the device under test 100. In this way, the focusing and leveling device 1 can adapt to different surface morphologies of the device under test 100, and the measurement range can be switched without changing the hardware.

[0090] In some embodiments, such as Figure 1 As shown, the measuring device 30 includes a detection component 302. The detection component 302 is used to receive the feedback beam reflected from the surface of the device under test 100 and convert the feedback beam into an electrical signal.

[0091] In one implementation, the detection component 302 may include an imaging lens and a photodetector. The imaging lens focuses the feedback beam onto the surface of the photodetector, and the photodetector outputs an electrical signal corresponding to the received light intensity. When the surface height of the device under test 100 changes, the incident position of the feedback beam changes accordingly, and the electrical signal output by the photodetector also changes accordingly.

[0092] In another implementation, the detection component 302 may include a detection grating 3021 and a detector array 3023. The detection grating 3021 and the projection grating 3011 in the projection component 301 form moiré fringes, and the surface height information of the device under test 100 carried by the feedback beam is manifested as a phase change of the moiré fringes. The detector array 3023 receives the moiré fringes and outputs an electrical signal corresponding to the phase of the fringes.

[0093] In some embodiments, such as Figure 1 As shown, the measuring device 30 also includes a processor 303. In addition to being connected to the control component 203 and the acquisition element 204, the processor 303 is also electrically connected to the detection component 302. The processor 303 is used to process the electrical signals output by the detection component 302 to determine the height information of the surface of the device under test 100.

[0094] In one implementation, the processor 303 receives the electrical signal output by the detection component 302 and calculates the height information of the surface of the device under test 100 based on a pre-calibrated correspondence between the electrical signal and height. Pre-calibration can be achieved by placing the device under test 100 at a known height, measuring the corresponding electrical signal value, and establishing a mapping relationship between height and electrical signal.

[0095] In another implementation, the processor 303 can perform differential processing on the electrical signals output by the detection component 302. The detection component 302 outputs multiple electrical signals, each corresponding to a beam of light with a different polarization state or spatial position. The processor 303 calculates the difference between each signal and calculates the height information of the surface of the device under test 100 based on the linear relationship between the difference signal and the height. Differential processing can eliminate the influence of intensity fluctuations of the light source 10 and changes in the surface reflectivity of the device under test 100 on the measurement results.

[0096] Thus, the focusing and leveling device 1 in this embodiment provides a stable incident beam through the beam stabilizing device 20, eliminating the interference of light source 10 pointing and positional offsets on the measurement, so that the measuring device 30 does not need to consider the fluctuation factors of the light source 10. The projection component 301, the detection component 302, and the processor 303 in the measuring device 30 cooperate with each other. The projection component 301 adjusts the magnification to change the measurement range, so that the focusing and leveling device 1 can select a suitable range according to the surface undulation of the device under test 100, avoiding insufficient measurement range or wasted measurement accuracy due to a fixed range. The detection component 302 converts the feedback beam into an electrical signal, and the processor 303 extracts height information from the electrical signal to form a complete measurement function. The beam stabilizing device 20, the projection component 301, the detection component 302, and the processor 303 cooperate with each other, so that the measuring device 30 can obtain stable measurement results on the device under test 100 with different surface morphologies, improving the adaptability and accuracy of the measurement.

[0097] In some embodiments, the beam stabilization device 20 keeps the maximum angular deviation of the probe beam below a preset threshold so that the maximum offset range of the probe beam on the surface of the device under test 100 is less than the measurement error of the focusing and leveling device 1.

[0098] When the light source 10 experiences a pointing deviation, the angular pointing of the probe beam deviates. Upon detecting this pointing deviation, the beam stabilization device 20 drives the beam splitting adjustment component 201 to compensate for the transmission direction of the probe beam, restoring the angular pointing of the probe beam to the preset reference information. After compensation, the maximum angular deviation of the probe beam is controlled within a preset threshold. the following.

[0099] Similarly, when the light source 10 experiences a lateral position shift, the propagation path of the probe beam undergoes a parallel shift. After detecting this position shift, the beam stabilization device 20 drives the beam splitting adjustment component 201 to compensate for the transmission angle of the probe beam. By adjusting the angle, the spot position of the probe beam on the surface of the device under test 100 is indirectly corrected, restoring the spot position to the position parameters corresponding to the preset reference information.

[0100] Specifically, the probe beam forms a measurement spot on the surface of the device under test 100, and the position of the spot moves as the angle of the probe beam changes. Let the focal length of the projection component 301 in the measuring device 30 be f, and the incident angle of the probe beam onto the surface of the device under test 100 be θ. Then the angle deviation The range of spot offset induced on the surface of the device under test 100 is: When the maximum angular deviation is controlled within a preset threshold The maximum offset range of the light spot is as follows: Similarly, positional offset. X will also cause a corresponding spot shift on the surface of the device under test 100.

[0101] When the detection and compensation of the beam stabilization device 20 control the maximum angle deviation and the maximum position offset to be below the preset threshold, the total offset range of the light spot is less than the measurement error allowed by the focusing and leveling device 1. Therefore, the maximum offset range of the probe beam on the surface of the device under test 100 is less than the measurement error of the focusing and leveling device 1, and the influence of the state change of the probe beam on the measurement result can be ignored.

[0102] It is worth noting that without the beam stabilization device 20, the position and pointing information of the probe beam emitted from the light source 10 cannot remain stable. Because the position and pointing offsets of the light source 10 occur at high frequencies, the height adjustment mechanism on the surface of the device under test 100 cannot compensate for these high-frequency changes. Therefore, it is impossible to eliminate the beam offset by adjusting the position of the device under test 100 in the Z direction. The offset error of the probe beam on the surface of the device under test 100 will be superimposed on the measurement signal, causing the focusing and leveling device 1 to be unable to distinguish whether the change in the feedback beam is caused by a change in the height of the device under test 100 or by the offset of the light source 10, thus generating measurement errors.

[0103] By setting the beam stabilization device 20, the positional offset and angular deviation of the probe beam are controlled below the preset threshold, so that the influence of the offset of the light source 10 on the measurement accuracy is suppressed within an acceptable range. At the same time, the problem that high-frequency offset cannot be compensated by the device under test 100 in the Z-direction motion is solved.

[0104] Furthermore, by It can be seen that the maximum offset range of the probe beam on the surface of the device under test 100 is positively correlated with the maximum angular deviation of the probe beam, the focal length of the projection component 301 in the measuring device 30, and the incident angle of the probe beam onto the surface of the device under test 100.

[0105] Specifically, the preset threshold can be 0.1°. Setting the preset threshold corresponding to the maximum angular deviation of the probe beam to 0.1° can reliably limit the angular jitter of the probe beam to a small range, so that the maximum offset of the light spot on the surface of the device under test 100 is effectively controlled within the allowable measurement error of the focusing and leveling device 1. This avoids the introduction of additional measurement errors due to excessive angular deviation, and does not require excessively high control precision. It achieves a balance between control effect and measurement accuracy, ensuring the stability and accuracy of the focusing and leveling device 1.

[0106] In some embodiments, such as Figure 1 and Figure 2 As shown, the projection assembly 301 includes a projection grating 3011. The projection grating 3011 is disposed on the outgoing light path of the beam stabilizing device 20 and is used to split the probe beam into multiple sub-beams. Specifically, the projection grating 3011 is located on the reflected light path of the first beam splitting element 2012.

[0107] The projection grating 3011 can be a transmissive grating, and the glass substrate of the projection grating 3011 is coated with an Al or Cr metal layer. For example... Figure 3 As shown, the surface of the projection grating 3011 has a periodically arranged first opaque region 3011a and a first transparent region 3011b. After the probe beam passes through the projection grating 3011, it can form a striped beam of light and dark alternating patterns. The grating period of the projection grating 3011 determines the spacing between adjacent sub-beams; the larger the grating period, the larger the spacing between the sub-beams.

[0108] The grating period of the projection grating 3011 can be selected between 8 micrometers and 200 micrometers. When the grating period of the projection grating 3011 is small, the spacing between the multiple sub-beams formed is small, the measurement range of the focusing and leveling device 1 is small, but the measurement accuracy is high. When the grating period of the projection grating 3011 is large, the spacing between the multiple sub-beams formed is large, the measurement range of the focusing and leveling device 1 is large, but the measurement accuracy is correspondingly reduced. The grating period of the projection grating 3011 can be selected according to the degree of undulation of the surface of the device under test 100 to match the required measurement range.

[0109] In some embodiments, such as Figure 1 and Figure 2As shown, the projection assembly 301 also includes a projection optical unit 3012. The optical projection unit is disposed in the outgoing light path of the projection grating 3011 and is used to project the sub-beam formed by the projection grating 3011 onto the surface of the device under test 100. The projection optical unit 3012 has a variable magnification, and the imaging size and spacing of the sub-beam on the surface of the device under test 100 can be adjusted by changing the magnification.

[0110] When the magnification increases, the imaging size of the sub-beam on the surface of the device under test 100 increases, the spacing between adjacent sub-beams increases, the measurement sensitivity of the focusing and leveling device 1 increases, but the measurement range decreases; when the magnification decreases, the spacing between sub-beams decreases, the measurement range of the focusing and leveling device 1 increases, and the measurement sensitivity decreases.

[0111] In one implementation, the projection optical unit 3012 may include a zoom lens group, comprising at least two lens groups, and the magnification is adjusted by changing the spacing between the lens groups.

[0112] In another implementation, the projection optics unit 3012 may include a combination of an adjustable beam expander and a fixed-focus lens. The adjustable beam expander changes the diameter of the probe beam, and the fixed-focus lens projects the expanded beam onto the surface of the device under test 100.

[0113] It is worth noting that the measuring range of the focusing and leveling device 1 is... , ,in, Let K be the grating frequency of the projection grating 3011, which is the reciprocal of the grating period. K is a coefficient, and K∝α×M1, where α is the incident angle of the probe beam onto the surface of the device under test 100, and M1 is the magnification of the projection optical unit 3012. Therefore, the measurement range of the focusing and leveling device 1 is inversely proportional to the grating frequency (i.e., directly proportional to the grating period) and negatively correlated with the incident angle and magnification. By selecting appropriate grating periods, incident angles, and magnifications, the focusing and leveling device 1 can adapt to devices under test 100 with different surface undulations.

[0114] For example, when measuring a device under test 100 with a large surface undulation, a projection grating 3011 with a large grating period can be selected, detection can be performed at a smaller incident angle, or a projection optical unit 3012 with a smaller magnification can be used to obtain a larger measurement range, ensuring that the height variation of the surface of the device under test 100 does not exceed the measurement range of the focusing and leveling device 1. When measuring a device under test 100 with a flat surface, a projection grating 3011 with a smaller grating period can be selected, detection can be performed at a larger incident angle, or a projection optical unit 3012 with a larger magnification can be used to obtain a smaller measurement range and higher measurement accuracy.

[0115] Thus, in this embodiment, the projection component 301 divides the probe beam into multiple sub-beams through the projection grating 3011 and changes the magnification through the projection optical unit 3012. By combining the influence of the period of the projection grating 3011, the incident angle, and the magnification on the measurement range, the focusing and leveling device 1 can select a suitable range according to the degree of undulation of the surface of the device under test 100. This avoids the problem of insufficient measurement range or wasted measurement accuracy due to a fixed range, and improves the adaptability of the focusing and leveling device 1 to different surface morphologies of the device under test 100.

[0116] In some embodiments, the projection optical unit 3012 can make the principal ray of the sub-beam parallel to the optical axis of the projection optical unit 3012 on both the incident and exit sides.

[0117] In one implementation, the projection optical unit 3012 can be a dual telecentric optical unit. The dual telecentric optical unit includes an object-side telecentric optical path and an image-side telecentric optical path. In the object-side telecentric optical path, an aperture stop is positioned on the image-side focal plane, making the object-side principal ray parallel to the optical axis; in the image-side telecentric optical path, an aperture stop is positioned on the object-side focal plane, making the image-side principal ray parallel to the optical axis. With this structure, the projection optical unit 3012 can ensure that the principal ray of the sub-beam is parallel to the optical axis on both the incident side (the side of the projection grating 3011) and the exit side (the side of the device under test 100).

[0118] In another implementation, the projection optics unit 3012 may include a dual telecentric lens. The dual telecentric lens includes positive and negative lens groups, such as a positive + negative + positive lens combination or a negative + positive + negative lens combination. An aperture stop is positioned at the focal plane between the front and rear lens groups. When the sub-beam enters from the front lens group, the principal ray converges at the center of the aperture stop after passing through the front lens group, and exits from the aperture stop, becoming parallel light after passing through the rear lens group. Thus, the principal ray of the sub-beam on the projection grating 3011 side is parallel to the optical axis, and the principal ray on the device under test 100 side is also parallel to the optical axis.

[0119] The projection optics unit 3012 ensures that the principal ray of the sub-beam is parallel to the optical axis on both the incident and exit sides, reducing magnification errors caused by changes in the surface position of the device under test 100 or the position of the projection grating 3011. When the surface height of the device under test 100 changes, the imaging position of the sub-beam on the surface of the device under test 100 will not shift laterally due to defocusing, thereby improving measurement stability. Simultaneously, the magnification of the projection optics unit 3012 does not change with the object distance, which helps maintain the stability of the measurement range.

[0120] In some embodiments, the projection optical unit 3012 includes a first lens group and a second lens group. The first lens group is disposed in the output light path of the projection grating 3011 and is used to receive the sub-beam emitted from the projection grating 3011. The second lens group is disposed in the output light path of the first lens group and is used to project the sub-beam onto the surface of the device under test 100. The distance between the second lens group and the first lens group is adjustable, and the magnification of the projection optical unit 3012 can be changed by changing the distance between the two lens groups.

[0121] In a practical implementation, the first lens group and the second lens group can each include a combination of positive and negative lenses, such as a positive + negative + positive lens combination or a negative + positive + negative lens combination. By moving the position of the second lens group relative to the first lens group, the focal length of the entire projection optical unit 3012 can be changed, thereby changing the magnification of the projection optical unit 3012.

[0122] For example, when the distance between the first lens group and the second lens group increases, the magnification increases, the imaging size of the sub-beam on the surface of the device under test 100 increases, the spacing between adjacent sub-beams increases, the measurement sensitivity of the focusing and leveling device 1 increases, but the measurement range decreases; when the distance between the first lens group and the second lens group decreases, the magnification decreases, the spacing between sub-beams decreases, the measurement range increases, but the measurement sensitivity decreases.

[0123] In practice, the first lens group is fixed, while the second lens group can move along the optical axis. By driving the second lens group through a drive mechanism, the distance between the two lens groups can be precisely adjusted, thereby achieving continuous adjustment of the magnification.

[0124] In some embodiments, the first lens group is used to make the principal ray of the sub-beam parallel to the optical axis on the incident side of the projection optical unit 3012. The incident side refers to the side on which the beam enters the projection optical unit 3012, i.e., the side facing the projection grating 3011. The front focal plane of the first lens group coincides with the position of the projection grating 3011. When the sub-beam exits the projection grating 3011 and passes through the first lens group, the principal ray is refracted to a direction parallel to the optical axis.

[0125] In some embodiments, the second lens group is used to make the principal ray of the sub-beam parallel to the optical axis on the exit side of the projection optical unit 3012. The exit side refers to the side of the beam that leaves the projection optical unit 3012, i.e., the side facing the device under test 100. The back focal plane of the second lens group coincides with the surface of the device under test 100. After the sub-beam passes through the second lens group, the principal ray is emitted in a direction parallel to the optical axis and forms an image on the surface of the device under test 100.

[0126] Thus, when the height of the surface of the device under test 100 changes, the imaging position of the sub-beam on the surface of the device under test 100 will not be laterally shifted due to defocusing, thereby improving the measurement stability of the focusing and leveling device 1.

[0127] In some embodiments, such as Figure 1 and Figure 2 As shown, the detection component 302 includes a detection grating 3021. The detection grating 3021 is used to receive the feedback beam and form moiré fringes. The detection grating 3021 and the projection grating 3011 in the projection component 301 have an optical object-image relationship. When the surface height of the device under test 100 changes, a relative horizontal shift occurs between the image of the projection grating 3011 and the detection grating 3021, forming moiré fringes according to the interference principle. The light intensity distribution of the moiré fringes changes with the surface height of the device under test 100.

[0128] like Figure 3 As shown, the detection grating 3021 can be a transmissive grating, with periodically arranged second opaque regions 3021a and second transmissive regions 3021b on its surface. The second opaque regions 3021a and the second transmissive regions 3021b are arranged in a periodic alternation pattern. The second transmissive region 3021b allows the feedback beam to pass through, while the second opaque region 3021a blocks the feedback beam from passing through. After the feedback beam passes through the detection grating 3021, it interferes with the image of the projection grating 3011, forming alternating bright and dark moiré fringes.

[0129] The periods of the projection grating 3011 and the probe grating 3021 can be the same or similar. When the image of the projection grating 3011 and the probe grating 3021 are relatively displaced, periodic overlapping grating fringes are formed. When the device under test 100 is at zero position, half of all the sub-spots transmitted through the projection grating 3011 are imaged on the metal coating of the probe grating 3021, and the other half are imaged on the uncoated area. The device under test 100 being at zero position means that the surface of the device under test 100 is at the preset reference height position of the focusing and leveling device 1, that is, the reference plane set by the focusing and leveling device 1 during calibration. The deviation between the actual height of the device under test 100 and this preset reference height is the defocusing amount of the device under test. .

[0130] Moiré fringes carry polarization information. This polarization information contains the polarization direction of the polarized light beam. There are at least two polarized light beams, including a first polarized beam and a second polarized beam. The first polarized beam corresponds to the S-polarization direction, and the second polarized beam corresponds to the P-polarization direction.

[0131] Figure 4 This diagram illustrates the formation process of a projection grating, a probe grating, and moiré fringes in a focusing and leveling device provided in this application embodiment. The diagram demonstrates the principle of moiré fringe generation. Exemplarily, Figure 4(a) in the diagram illustrates that the projection grating 3011 is a reference grating with a period of 8 μm, used to modulate the incident light into a periodic striped sub-beam. Figure 4 (b) in the diagram illustrates that the detector grating 3021 is a receiving grating with a period of 10 μm, which is in an optical image relationship with the projection grating 3011, and is used to receive the feedback beam and form interference fringes. Figure 4 The reflected grating shown in (c) is an image formed on the plane of the probe grating 3021 after the projection grating 3011 is reflected by the device under test 100. When the device under test 100 is defocused, this image is horizontally offset relative to the probe grating 3021. Figure 4 (d) indicates that the moiré fringes are formed by the interference between the projected grating image and the probe grating due to periodic differences and relative horizontal offset. They are alternating bright and dark grating fringes, and their light intensity distribution changes synchronously with the defocusing amount, realizing the conversion of height information into light intensity information.

[0132] In some embodiments, the detection assembly 302 includes a polarization beam splitter 3022. The polarization beam splitter 3022 is disposed in the outgoing light path of the detection grating 3021 and is used to split the moiré fringes into multiple groups of polarized beams with different polarization states. The polarization beam splitter 3022 can be a polarization beam splitter. Based on the aforementioned polarization information, the polarization beam splitter 3022 can separate polarized light into first polarized light and second polarized light, and guide the first polarized light and second polarized light in different directions before entering the detector array 3023.

[0133] In some embodiments, the detection component 302 further includes a detector array 3023. The detector array 3023 includes two independent photodetectors, namely a first detector and a second detector. The first detector and the second detector are used to receive first polarized light and second polarized light, respectively.

[0134] like Figure 5 As shown, the detector array 3023 is a quadrant detector. Its left half-region 3023a corresponds to the first detector, which is used to receive the light beam with the first polarization direction, i.e., the first polarized light. The right half-region 2023b corresponds to the second detector, which is used to receive the light beam with the second polarization direction, i.e., the second polarized light.

[0135] In practical applications, when the surface height of the device under test 100 changes, the relative horizontal offset between the image of the projection grating 3011 and the detection grating 3021 changes accordingly, causing a corresponding change in the light intensity distribution of the moiré fringes. The first detector located in the left half of the region receives the light signal of the first polarized light and converts it into a first electrical signal, while the second detector located in the right half of the region receives the light signal of the second polarized light and converts it into a second electrical signal. The processor 303 performs differential calculations on the two electrical signals to achieve accurate calculation of the height information.

[0136] Specifically, the electrical signals converted from the polarized beam acquired by the detector array 3023 are as follows: , The two sets of signals are obtained after differential processing. . The defocusing amount of the device under test. Phase difference satisfy: And within the 1 / 4 periodic linear region of the sine function, it satisfies .in, The phase difference of the polarized beam. The coefficients are linear, and π is the constant of pi. As the reference light intensity, The amplitude coefficient of the interference signal. The grating frequency of the projection grating. This represents the magnification of the projection optical unit. To detect the angle between the beam and the normal of the device under test.

[0137] From the above formula, we can derive: defocus amount Changes will directly cause phase difference The linear change of the differential electrical signal, in turn, causes the differential electrical signal to... The corresponding change occurs, therefore the defocusing amount can be solved in reverse by detecting the differential electrical signal. This enables height measurement.

[0138] Figure 6 This demonstrates the relationship between the intensity of the differential electrical signal and the defocusing amount of the device under test 100. The correspondence between them, with the horizontal axis representing the defocus amount. The vertical axis represents the differential electrical signal intensity, and the data points are distributed along a straight line, indicating that within the selected measurement range, the differential electrical signal intensity and the defocus amount have a good linear relationship. This linear relationship is the basis for calculating the surface height of the device under test through the electrical signal, and can realize the direct linear conversion from defocus amount to height information.

[0139] Therefore, it can be seen that the electrical signal output by the detector array 3023 is related to the defocusing amount of the device under test 100. There is a correlation between them: the detector array 3023 acquires the electrical signals corresponding to beams with different polarization states, performs differential processing to eliminate common-mode interference, and then utilizes the phase difference... As an intermediate correlation quantity, the light intensity signal Height information of the device under test 100 Establishing a linear correspondence provides a mathematical basis for the processor 303 to subsequently calculate the surface height of the device under test 100, and provides a data foundation for the detection component 302 to achieve accurate height measurement.

[0140] Thus, the detection component 302 converts the feedback beam into moiré fringes through the detection grating 3021, separates beams with different polarization directions through the polarization beam splitter 3022, and then converts the optical signal into an electrical signal through the detector array 3023. After differential processing and verification compensation by the processor 303, the surface height of the device under test 100 is accurately measured. In conjunction with the variable focus characteristics of the projection component 301 and the light stabilization function of the light source 10 stabilization device, the overall measurement performance of the focusing and leveling device 1 is further guaranteed, meeting the practical application requirements of high-precision measurement.

[0141] Based on the above formula, the differential electrical signal satisfies... defocus amount Phase difference satisfy Differential electrical signal With defocus satisfy: Therefore, differential electrical signals With defocus The distribution between them follows a sinusoidal function. Within a complete cycle of the sinusoidal function, there exists a linear region, which is the preset range. The preset range (linear region) is taken as approximately 1 / 4 of the sinusoidal function's cycle. Within this 1 / 4-cycle linear region, the defocusing amount of the device under test is... With differential electrical signals It exhibits a good linear relationship, that is, it satisfies .

[0142] The reason for choosing 1 / 4 of the period as the linear working interval is because within this interval... The phase difference and the defocus amount are approximately linear, and the differential electrical signal and the defocus amount are also approximately linear, which can avoid the calculation distortion caused by the nonlinear region and ensure measurement accuracy and stability.

[0143] Figure 7 This application provides a focusing and leveling device 1 with different polarization states of optical signals and differential electrical signals varying with the defocus amount, illustrating the defocus response curves. The figure shows the variation of the electrical signal output by the detector array 3023 and the defocus amount of the device under test 100, and clarifies the effective linear range for height measurement: the first and second electrical signals exhibit periodic sinusoidal changes with the defocus amount, with opposite phases. The differential electrical signal, obtained by subtracting the first and second electrical signals, also exhibits a periodic sinusoidal distribution, with an amplitude twice that of a single-channel signal. The linear region is the 1 / 4 sinusoidal period interval of the differential electrical signal near zero. Within this interval, the differential electrical signal is approximately linearly correlated with the defocus amount, representing the effective range for height measurement. This avoids calculation errors caused by nonlinear regions, ensuring measurement accuracy.

[0144] Thus, within this 1 / 4 period linear region, measurement deviations caused by the nonlinear region of the sine function can be avoided, thereby improving the defocusing amount. The accuracy of the calculation depends on the range of the linear region, which in turn determines the size of the measurement range.

[0145] In some embodiments, the detection assembly 302 further includes a second focusing element 3025. The second focusing element 3025 is disposed in the output optical path of the polarization beam splitter 3022 and is used for beam focusing, improving light energy utilization, matching the size of the detector array 3023, and optimizing the signal-to-noise ratio.

[0146] Specifically, the second focusing element 3025 converges the first and second polarized light emitted from the polarization beam splitter 3022, enabling the beam to be efficiently incident on the detection surface of the detector array 3023. Through this converging effect, the dispersed beam is focused onto the effective detection area of ​​the detector array 3023, avoiding light energy loss. Furthermore, depending on the size of the detection surface of the detector array 3023, the second focusing element 3025 can also adjust the degree of convergence of the polarized beam to ensure that the spot size matches the detection area of ​​the detector array 3023.

[0147] In some embodiments, the detection assembly 302 further includes a filter element 3026. The filter element 3026 is disposed in the outgoing light path of the second focusing element 3025 and is mainly used to filter out stray light, select a preset wavelength, improve the signal-to-noise ratio, and prevent the detector array 3023 from saturating.

[0148] There may be stray light in the optical path from the light source 10, reflection from the surface of the optical element, or ambient light. This stray light will be superimposed on the effective signal and introduce measurement error. The filter element 3026 can effectively filter out stray light and improve the purity of the electrical signal.

[0149] In some embodiments, the detection assembly 302 further includes a detection imaging element 3024. The detection imaging element 3024 is disposed between the detection grating 3021 and the device under test 100, and is used to receive the feedback beam and to image the feedback beam onto the detection grating 3021.

[0150] The projection grating 3011 divides the light beam into multiple striped sub-beams. The multiple sub-beams are projected onto the device under test 100 by the optical projection unit. The sub-beams are reflected by the device under test 100 to form a feedback beam, which enters the detection imaging element 3024.

[0151] The detection imaging element 3024 can be a dual telecentric optical module, possessing dual telecentric imaging characteristics. In this way, the detection imaging element 3024 can eliminate imaging distortion caused by changes in the surface height of the device under test 100, ensuring that the grating image carried by the feedback beam is accurately projected onto the detection grating 3021, providing a stable and accurate imaging basis for the subsequent formation of interference fringes.

[0152] like Figure 1 As shown, the measuring device 30 may also include a third reflector 304 and a fourth reflector 305 to adjust the optical path structure.

[0153] A second aspect of this application also provides a semiconductor device, including a focusing and leveling device 1, wherein the focusing and leveling device 1 is the focusing and leveling device 1 as described in any of the above embodiments. It is understood that the semiconductor device employing the focusing and leveling device 1 of the above embodiments has all the technical effects of the focusing and leveling device 1 of the above embodiments, and will not be repeated here.

[0154] Specifically, the semiconductor equipment can be a photolithography device, a wafer inspection device, or a laser processing device. For example, during the operation of the photolithography device, the flatness of the surface of the device under test 100 (wafer) directly affects the quality and resolution of the exposed pattern. The processor 303 in the focusing and leveling device 1 monitors the height change of the surface of the device under test 100 in real time and feeds the measurement results back to the workpiece stage control system 2. The workpiece stage control system 2 can drive the device under test 100 to move via the drive component 3, ensuring that the wafer of the device under test is always within the optimal focal plane of the focusing and leveling device 1, thereby achieving high-precision exposure.

[0155] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A focusing and leveling device, characterized in that, include: A light source used to emit a probe beam; A beam stabilization device is disposed on the output light path of the light source. The beam stabilization device is used to detect the position information and pointing information of the probe beam, and adjust the transmission direction of the probe beam according to the deviation of the position information and pointing information from the preset reference information, so as to keep the probe beam emitted by the beam stabilization device stable. A measuring device is disposed on the output optical path of the beam stabilizing device. The measuring device is used to receive the probe beam that has been stabilized and adjusted by the beam stabilizing device, to project the probe beam onto the surface of the device under test, and to receive the feedback beam reflected by the surface of the device under test to determine the height information of the surface of the device under test. The measuring device includes: A projection component, disposed in the output optical path of the beam stabilization device, is used to project the stabilized probe beam onto the surface of the device under test. The magnification of the projection component is adjustable to adjust the measurement range of the focusing and leveling device. The projection component includes a projection grating and a projection optical unit. The projection grating is disposed in the output optical path of the beam stabilization device; the projection optical unit is disposed in the output optical path of the projection grating and is used to change the magnification of the projection component. The measurement range of the focusing and leveling device is directly proportional to the grating period of the projection grating and inversely proportional to the incident angle of the probe beam onto the surface of the device under test and the magnification of the projection optical unit. A detection component is used to receive the feedback beam reflected from the surface of the device under test and convert it into an electrical signal. The detection component includes a detection grating, a polarization beam splitter, and a detector array. The detection grating is disposed on the propagation path of the feedback beam and is used to receive the feedback beam and form moiré fringes. The polarization beam splitter is disposed on the output optical path of the detection grating and is used to separate the moiré fringes into polarized beams with at least two different polarization directions. The detector array is disposed on the output optical path of the polarization beam splitter and includes at least two detectors for receiving the polarized beams with at least two different polarization directions and converting them into corresponding electrical signals. A processor, electrically connected to the detection component, is used to perform differential processing on the electrical signal to determine the height information of the surface of the device under test.

2. The focusing and leveling device according to claim 1, characterized in that, The beam stabilization device includes: A beam splitting adjustment component is disposed on the output light path of the light source. The beam splitting adjustment component is used to adjust the transmission direction of the detection beam and split the detection beam into a first beam and a second beam. A detection component is used to receive the first beam and obtain the position information and pointing information of the detection beam based on the first beam; the second beam is used to enter the measuring device. A control component, electrically connected to the detection component and the beam splitting adjustment component respectively, is used to control the beam splitting adjustment component to compensate for the transmission direction of the detection beam based on the deviation between the position information and the pointing information detected by the detection component and the preset reference information.

3. The focusing and leveling device according to claim 2, characterized in that, The spectral modulation component includes: An adjustment element is disposed in the output light path of the light source and is used to adjust the transmission direction of the detection beam in a first direction; A first beam splitter is disposed on the output light path of the adjustment element. The first beam splitter is used to adjust the transmission direction of the detection beam in the second direction and split the detection beam into the first beam and the second beam.

4. The focusing and leveling device according to claim 3, characterized in that, The detection component includes: The second beam splitter is disposed on the transmission path of the first beam splitter, and the second beam splitter splits the first beam into a transmission sub-beam and a reflection sub-beam; The first detection unit is used to receive the transmitted sub-beam to obtain the position information of the detection beam; The second detection unit is used to receive the reflective sub-beam to obtain the pointing information of the detection beam.

5. The focusing and leveling device according to claim 4, characterized in that, The first detection unit includes: A first photodetector is disposed in the transmission optical path of the second beam splitter, and the first photodetector is a quadrant detector or a position-sensitive detector.

6. The focusing and leveling device according to claim 4, characterized in that, The second detection unit includes: The first focusing element is disposed in the reflected light path of the beam-splitting element; A second photodetector is disposed in the outgoing optical path of the first focusing element to obtain the pointing information of the detection beam.

7. A semiconductor device, characterized in that, include: The focusing and leveling device as described in any one of claims 1 to 6.

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