Dark-field confocal microscopy measurement device and method based on time-varying fractional-order vortex demodulation

Abstract

The present application discloses a dark-field confocal microscopy measurement device and method based on time-varying fractional-order vortex demodulation, relating to the field of confocal microscopy measurement technology. The device comprises a time-varying modulated illumination module, an optical scanning module, a signal acquisition and demodulation module, a function generator and a sample stage. The function generator is respectively connected to the time-varying modulated illumination module and the signal acquisition and demodulation module to provide reference signals to the time-varying modulated illumination module and the signal acquisition and demodulation module respectively. The sample stage is used to place a sample to be measured. The time-varying modulated illumination module is used to emit fractional-order vortex light to the optical scanning module. The optical scanning module is used to transmit the fractional-order vortex light to the sample to be measured in the sample stage and transmit the return light signal to the signal acquisition and demodulation module. The signal acquisition and demodulation module is used to collect the return light signal and perform dark-field confocal detection on the return light signal according to the reference signal to obtain measurement information of the sample to be measured. The present application can improve the sensitivity and accuracy of the measuring device.

Description

Technical Field

[0001] The present application relates to the field of confocal microscopy measurement technology, and in particular to a dark-field confocal microscopy measurement device and method based on time-varying fractional-order vortex demodulation. Background Art

[0002] Interlayer defects (such as holes, stacking faults, etc.) of three-dimensional integrated circuits can easily lead to a decrease in the electrical performance and life of the integrated circuits. Therefore, the detection of interlayer defects can ensure the yield of semiconductor three-dimensional integrated circuit products. Confocal microscopy measurement technology can be used for non-destructive defect detection of three-dimensional integrated circuits due to its three-dimensional tomography capability. However, the strong reflection information on the surface of the three-dimensional integrated circuit can easily drown out the weak interlayer defect scattering information, resulting in insufficient defect detection sensitivity and the inability to detect tiny defects at the nanometer scale. In a confocal system, the sensitivity of the measurement system reflects the system's ability to detect tiny signals. High sensitivity means that the system can detect smaller signal changes in the sample, thereby achieving a higher defect detection rate. In high-sensitivity defect detection, factors such as light source quality, environmental noise, and detector noise seriously affect the measurement accuracy of the confocal system, resulting in low system sensitivity and inaccurate measurements. Therefore, how to stably improve the sensitivity of the confocal system is a problem that those skilled in the art urgently need to solve. Summary of the Invention

[0003] The purpose of this application is to provide a dark-field confocal microscopy measurement device and method based on time-varying fractional-order vortex demodulation, which can improve the sensitivity of the confocal microscopy measurement device and enhance the accuracy of measurement.

[0004] To achieve the above objectives, this application provides the following solutions:

[0005] In the first aspect, the present application provides a dark-field confocal microscopy measurement device based on time-varying fractional-order vortex demodulation, wherein the dark-field confocal microscopy measurement device based on time-varying fractional-order vortex demodulation includes a time-varying modulated illumination module, an optical scanning module, a signal acquisition and demodulation module, a function generator and a sample stage, and the function generator is respectively connected to the time-varying modulated illumination module and the signal acquisition and demodulation module.

[0006] The function generator is used to provide reference signals for the time-varying modulation lighting module and the signal acquisition and demodulation module respectively.

[0007] The sample stage is used for placing the sample to be tested.

[0008] The time-varying modulation illumination module is used to emit fractional-order vortex light to the optical scanning module.

[0009] The optical scanning module is used to transmit the fractional-order vortex light to the sample to be tested in the sample stage, and, when the fractional-order vortex light reflects a return light signal on the sample to be tested, transmit the return light signal to the signal acquisition and demodulation module.

[0010] The signal acquisition and demodulation module is used to acquire the return light signal and perform dark field confocal detection on the return light signal according to the reference signal to obtain measurement information of the sample to be tested. The measurement information is a measurement result of whether the sample to be tested has defects based on dark field confocal detection.

[0011] Optionally, the time-varying modulated illumination module includes a laser, a half-wave plate, a polarizer, a first non-polarizing beam splitter and a spatial light modulator arranged in sequence, and the spatial light modulator is connected to the function generator.

[0012] The laser emits incident light, which passes through the half-wave plate, the polarizer and the first non-polarizing beam splitter in sequence before reaching the spatial light modulator. The spatial light modulator modulates the incident light into the fractional-order vortex light according to the reference signal, and transmits the fractional-order vortex light to the first non-polarizing beam splitter. The first non-polarizing beam splitter transmits the fractional-order vortex light to the optical scanning module.

[0013] Optionally, the optical scanning module includes a second non-polarization beam splitter, a galvanometer, a scanning lens, a tube lens and an objective lens, which are arranged in sequence.

[0014] The second non-polarization beam splitter is arranged opposite to the first non-polarization beam splitter, and the objective lens is arranged opposite to the sample stage.

[0015] The second non-polarizing beam splitter receives the fractional-order vortex light emitted from the first non-polarizing beam splitter. The fractional-order vortex light passes through the galvanometer, the scanning lens, the tube lens and the objective lens in sequence and then irradiates the sample to be measured in the sample stage.

[0016] The objective lens receives the return light signal reflected by the sample to be tested, and transmits the return light signal to the tube lens, the scanning lens and the galvanometer in sequence before reaching the second non-polarizing beam splitter, and the second non-polarizing beam splitter transmits the return light signal to the signal acquisition and demodulation module.

[0017] Optionally, the signal acquisition and demodulation module includes an aperture, a focusing lens, a pinhole, a photomultiplier tube and a lock-in amplifier arranged in sequence.

[0018] The focusing lens and the second non-polarization beam splitter are arranged opposite to each other, and the aperture is arranged between the focusing lens and the second non-polarization beam splitter; the lock-in amplifier is connected to the function generator.

[0019] The aperture receives the return light signal transmitted by the second non-polarizing beam splitter, filters the return light signal, and retains the central scattered light signal. The central scattered light signal is focused to the pinhole by the focusing lens. The photomultiplier tube converts the central scattered light signal into an electrical signal, and then transmits the electrical signal to the lock-in amplifier. The lock-in amplifier demodulates the electrical signal according to the reference signal to obtain measurement information of the sample to be measured.

[0020] Optionally, the sample stage is an axial electric translation stage.

[0021] In the second aspect, the present application provides a dark-field confocal microscopy measurement method based on time-varying fractional-order vortex demodulation. The dark-field confocal microscopy measurement method based on time-varying fractional-order vortex demodulation is applied to the dark-field confocal microscopy measurement device based on time-varying fractional-order vortex demodulation as described in the first aspect. The dark-field confocal microscopy measurement method based on time-varying fractional-order vortex demodulation includes the following steps.

[0022] A time-varying modulation illumination module is used to emit fractional-order vortex light to an optical scanning module.

[0023] The optical scanning module is used to transmit the fractional-order vortex light to the sample to be tested in the sample stage. When the fractional-order vortex light reflects a return light signal on the sample to be tested, the return light signal is transmitted to the signal acquisition and demodulation module.

[0024] The signal acquisition and demodulation module is used to acquire the return light signal, and dark field confocal detection is performed on the return light signal according to the reference signal to obtain measurement information of the sample to be tested. The measurement information is a measurement result of whether the sample to be tested has defects based on dark field confocal detection.

[0025] Optionally, the time-varying modulation illumination module is used to emit fractional-order vortex light to the optical scanning module, which specifically includes the following contents.

[0026] The incident light is emitted by a laser, and the incident light passes through a half-wave plate, a polarizing plate and a first non-polarizing beam splitter in sequence before reaching a spatial light modulator.

[0027] The spatial light modulator is used to modulate the incident light into the fractional-order vortex light according to a reference signal, and the fractional-order vortex light is transmitted to the first non-polarization beam splitter.

[0028] The first non-polarization beam splitter transmits the fractional-order vortex light to the optical scanning module.

[0029] Optionally, the optical scanning module is used to transmit the fractional-order vortex light to the sample to be tested in the sample stage. When the fractional-order vortex light reflects an echo signal on the sample to be tested, the echo signal is transmitted to a signal acquisition and demodulation module, which specifically includes the following contents.

[0030] The fractional-order vortex light emitted from the first non-polarizing beam splitter is received by a second non-polarizing beam splitter, and the fractional-order vortex light is sequentially transmitted to a galvanometer, a scanning lens, a tube lens and an objective lens, and then irradiated onto the sample to be measured in the sample stage.

[0031] The objective lens is used to receive the return light signal reflected by the sample to be tested, and the return light signal is sequentially transmitted to the tube lens, the scanning lens and the galvanometer mirror before reaching the second non-polarization beam splitter.

[0032] The second non-polarization beam splitter is used to transmit the return light signal to the signal acquisition and demodulation module.

[0033] Optionally, the signal acquisition and demodulation module is used to acquire the return light signal, and dark field confocal detection is performed on the return light signal according to a reference signal to obtain measurement information of the sample to be measured, which specifically includes the following contents.

[0034] The return light signal transmitted by the second non-polarization beam splitter is received by using an aperture, and the return light signal is filtered to obtain a central scattered light signal.

[0035] The central scattered light signal is focused onto a pinhole by using a focusing lens, so that the central scattered light signal passes through the pinhole and is transmitted to a photomultiplier tube.

[0036] The central scattered light signal is converted into an electrical signal by using the photomultiplier tube, and the electrical signal is transmitted to a lock-in amplifier.

[0037] The lock-in amplifier is used to demodulate the electrical signal according to a reference signal to obtain measurement information of the sample to be measured.

[0038] Optionally, the sample stage is an axial electric translation stage.

[0039] According to the specific embodiments provided in this application, this application discloses the following technical effects:

[0040] The present application provides a dark-field confocal microscopy measurement device and method based on time-varying fractional-order vortex demodulation, in which fractional-order vortex light is emitted to an optical scanning module through a time-varying modulated illumination module. After the optical scanning module transmits the fractional-order vortex light to the sample to be measured in the sample stage, the return light signal reflected by the sample to be measured is transmitted to the signal acquisition and demodulation module. The return light signal is collected by the signal acquisition and demodulation module, and dark-field confocal detection is performed on the return light signal, thereby obtaining microscopic and nanometer-level measurement information related to the dark-field confocal detection of the sample to be measured. By using time-varying fractional-order vortex light as illumination light to highlight the scattering information, the signal strength of tiny defects can be improved, and the sensitivity and accuracy of defect detection of the device can be enhanced. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0042] Figure 1 A schematic structural diagram of a dark-field confocal microscopy measurement device based on time-varying fractional-order vortex demodulation provided in one embodiment of the present application.

[0043] Figure 2 A flowchart of a dark-field confocal microscopy measurement method based on time-varying fractional-order vortex demodulation is provided in one embodiment of the present application.

[0044] Figure 3 A schematic diagram of a dark-field confocal microscopy measurement method based on time-varying fractional-order vortex demodulation provided in one embodiment of the present application.

[0045] Description of reference numerals:

[0046] 1—Laser; 2—Half-wave plate; 3—Polarizer; 4—First non-polarizing beam splitter; 5—Spatial light modulator; 6—Second non-polarizing beam splitter; 7—Galvanometer; 8—Scanning lens; 9—Tube lens; 10—Objective lens; 11—Sample to be measured; 12—Axial motorized translation stage; 13—Aperture diaphragm; 14—Focusing lens; 15—Pinhole; 16—Photomultiplier tube; 17—Lock-in amplifier; 18—Function generator. DETAILED DESCRIPTION

[0047] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0048] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0049] In an exemplary embodiment, Figure 1 As shown, an embodiment of the present application provides a dark-field confocal microscopy measurement device based on time-varying fractional-order vortex demodulation, and the dark-field confocal microscopy measurement device based on time-varying fractional-order vortex demodulation includes a time-varying modulated illumination module, an optical scanning module, a signal acquisition and demodulation module, a function generator 18 and a sample stage, and the function generator 18 is respectively connected to the time-varying modulated illumination module and the signal acquisition and demodulation module.

[0050] The function generator 18 is used to provide reference signals for the time-varying modulation lighting module and the signal acquisition and demodulation module respectively.

[0051] The sample stage is used to place the sample 11 to be tested.

[0052] The time-varying modulation illumination module is used to emit fractional-order vortex light to the optical scanning module.

[0053] The optical scanning module is used to transmit the fractional-order vortex light to the sample to be tested 11 in the sample stage, and, when the fractional-order vortex light reflects an echo signal on the sample to be tested 11, transmit the echo signal to the signal acquisition and demodulation module.

[0054] The signal acquisition and demodulation module is configured to acquire the return light signal and perform dark-field confocal detection on the return light signal based on the reference signal to obtain measurement information of the sample 11. This measurement information is a defect-detection result of the sample 11 obtained through dark-field confocal detection. In other words, the dark-field confocal microscopy measurement device is ideal for nanoscale defect detection in semiconductor chips. Its purpose is to detect the presence of nanoscale defects at various measurement points on the semiconductor chip.

[0055] In this embodiment, the time-varying modulated illumination module comprises, in order of light propagation direction, a laser 1, a half-wave plate 2, a polarizer 3, a first non-polarizing beam splitter 4, and a spatial light modulator 5. The spatial light modulator 5 is connected to the function generator 18, which provides a reference signal for spatial light modulation. Laser 1 refers to a light source device capable of emitting laser light. In this embodiment, the laser light emitted by laser 1 serves as the initial incident light. Half-wave plate 2 refers to a birefringent crystal of a certain thickness. When normally incident light passes through it, the phase difference between the ordinary light and the extraordinary light is equal to π or an odd multiple thereof. Such a crystal is a half-wave plate 2, also known as a half-wave plate. Polarizer 3 refers to polarized glass, which has excellent optical properties such as light transmittance. Non-polarizing beam splitters have a light splitting function and are primarily used to split a single beam of light into two or more beams. Under active control, a spatial light modulator (SLM) can modulate a parameter of a light field through liquid crystal molecules. For example, this can be achieved by modulating the amplitude of the light field, modulating the phase through the refractive index, modulating the polarization state through polarization rotation, or converting incoherent light into coherent light. This allows information to be easily loaded into one- or two-dimensional light fields, rapidly processing the loaded information by leveraging the wide bandwidth and multi-channel parallel processing capabilities of light. SLMs are core components of systems such as real-time optical information processing, optical interconnects, and optical computing.

[0056] In this embodiment, the laser 1 emits incident light, and the incident light passes through the half-wave plate 2, the polarizer 3 and the first non-polarizing beam splitter 4 in sequence before reaching the spatial light modulator 5. The spatial light modulator 5 modulates the incident light into the fractional-order vortex light according to the reference signal, and feeds the fractional-order vortex light back to the first non-polarizing beam splitter 4 again, and then the first non-polarizing beam splitter 4 transmits the fractional-order vortex light to the optical scanning module.

[0057] In this embodiment, the optical scanning module is composed of a second non-polarizing beam splitter 6, a galvanometer 7, a scanning lens 8, a tube lens 9 and an objective lens 10 in order according to the direction of light propagation. The second non-polarizing beam splitter 6 is arranged opposite to the first non-polarizing beam splitter 4, and the objective lens 10 is arranged opposite to the sample stage. The second non-polarizing beam splitter 6 receives the fractional-order vortex light emitted from the first non-polarizing beam splitter 4. The fractional-order vortex light passes through the galvanometer 7, the scanning lens 8, the tube lens 9 and the objective lens 10 in sequence and then irradiates the sample to be tested 11 in the sample stage. The galvanometer 7 is a device for laser scanning, and the galvanometer 7 can swing at high speed to achieve rapid scanning and positioning of the laser beam. The scanning lens 8 is used to form a focused light spot of uniform size on a plane with the laser beam. The tube lens 9 is an optical element commonly used for imaging in microscopes. The objective lens 10 can be a lens group composed of a plurality of lenses. It is the most important optical component of a microscope and is mainly used to use light to image the object to be inspected for the first time.

[0058] In this embodiment, since the fractional-order vortex light reflects back a light return signal after being irradiated on the surface of the sample to be tested 11, the light return signal will also follow the original path and pass through the objective lens 10, the tube lens 9, the scanning lens 8, the galvanometer mirror 7, and the second non-polarizing beam splitter 6. First, the objective lens 10 receives the light return signal reflected from the sample to be tested 11 and transmits the light return signal to the tube lens 9, the scanning lens 8, and the galvanometer mirror 7 in sequence before reaching the second non-polarizing beam splitter 6. The second non-polarizing beam splitter 6 then transmits the light return signal to the signal acquisition and demodulation module.

[0059] In this embodiment, the signal acquisition and demodulation module comprises, in order of light propagation direction, an aperture 13, a focusing lens 14, a pinhole 15, a photomultiplier tube 16, and a lock-in amplifier 17. The focusing lens 14 is positioned opposite the second non-polarizing beam splitter 6, with the aperture 13 positioned between them. The lock-in amplifier 17 is connected to the function generator 18, which provides a reference signal for the lock-in amplifier 17. The aperture 13 refers to an entity in an optical system that restricts the light beam. It can be the edge of a lens, a frame, or a specially designed perforated screen. It can be used to restrict the light beam or the size of the field of view (imaging range). The focusing lens 14 is a gradient refractive index lens with end-face focusing and imaging properties, as well as a cylindrical shape. The pinhole 15 is a circular aperture with a diameter of tens of microns. Pinhole 15 is used to filter tiny point light sources in the optical path, filter laser beams, and so on. Photomultiplier tubes 16 are vacuum electronic devices that convert weak optical signals into electrical signals. They are used in optical measuring instruments and spectral analysis instruments. They can measure extremely weak radiation power with wavelengths between 200 and 1200 nanometers in low-energy photometry and spectroscopy. Lock-in amplifiers 17 are amplifiers that can isolate specific carrier frequency signals from highly noisy environments.

[0060] In this embodiment, the aperture 13 receives the return light signal transmitted by the second non-polarization beam splitter 6, filters the return light signal, and retains the central scattered light signal. The central scattered light signal is focused to the pinhole 15 by the focusing lens 14. The photomultiplier tube 16 converts the central scattered light signal into an electrical signal, and then transmits the electrical signal to the lock-in amplifier 17. The lock-in amplifier 17 demodulates the electrical signal according to the reference signal to obtain measurement information of the sample to be measured 11.

[0061] In this embodiment, the lock-in amplifier 17 amplifies and demodulates the measurement electrical signal according to the input reference signal at the same frequency as the phase switching frequency of the spatial light modulator 5 to obtain the nanoscale sample weak information of the sample to be measured 11.

[0062] It should be noted that the various optical elements in the time-varying modulation illumination module, the optical scanning module, the signal acquisition and demodulation module, and the function generator 18 in this embodiment, the above-mentioned individual optical elements are common optical elements in this field, and the functions and effects of each optical element are common knowledge in this field and will not be repeated here.

[0063] In this embodiment, the sample stage can be an automatic translation stage or a manual translation stage. In this embodiment, an automatic translation stage is preferred. The automatic translation stage is preferably an axial electric translation stage 12. The axial electric translation stage 12 can automatically perform axial displacement in an electric manner. Since the sample to be tested 11 is placed on the axial electric translation stage 12, the automatic axial displacement of the axial electric translation stage 12 can realize the scanning measurement of the sample to be tested 11 by the device, thereby obtaining more comprehensive sample information of the sample to be tested 11.

[0064] Based on the structure of the dark-field confocal microscopy measurement device provided in this embodiment, its working process mainly includes the following contents.

[0065] (a) The time-varying fractional-order vortex light is modulated by the spatial light modulator 5. First, two different fractional-order vortex phase images are loaded into the spatial light modulator 5. The phase distributions are exp(il1φ) and exp(il2φ) and the superposition of the same blazed grating, where φ is the angular coordinate of the liquid crystal surface of the spatial light modulator 5, l1 and l2 are orders, satisfying 1-l1=l2-1, |l1|>0.5, |l2|>0.5, the blazed grating period is M, the phase image is a grayscale image, and the grayscale 0-255 linearly corresponds to 0-2π. A reference signal is provided by the function generator 18 to trigger the spatial light modulator 5 to quickly switch between the two fractional-order vortex phase images, thereby modulating the ordinary incident light emitted by the laser 1 into time-varying fractional-order vortex light.

[0066] In this embodiment, the time-varying fractional-order vortex light refers to fractional-order vortex light with rapidly switching orders. Fractional-order vortex light is a type of light with a spiral phase structure, zero central light intensity, a unique radial notch in the light spot, and a definite orbital angular momentum. These characteristics give fractional-order vortex light broad application prospects in various fields such as optical measurement.

[0067] In this embodiment, the two fractional-order vortex phase images in the spatial light modulator 5 are switched in a triggered manner. Function generator 18 outputs two identical periodic signals as reference signals. One reference signal is input to the spatial light modulator 5 to trigger the image modulation process, with a frequency greater than 1 kHz. The other reference signal is input to the lock-in amplifier 17, causing it to demodulate at the same frequency as the phase switching, with a time constant greater than 2-3 times the period of the reference signal.

[0068] (b) The fractional vortex light sequentially passes through the galvanometer 7, the scanning lens 8, the tube lens 9, and the objective lens 10 and is focused on the surface of the sample 11 to be measured.

[0069] In this embodiment, the incident light emitted by the laser 1 is parallel light, and the polarization state is adjusted to the spatial light modulator 5 through the half-wave plate 2 and the polarizer 3. After the parallel light enters the spatial light modulator 5 at a certain angle, it is modulated by the spatial light modulator 5 into fractional-order vortex light with rapidly switching orders. The blazed grating period M is adjusted so that the emitted first-order diffraction light is coaxial with the subsequent optical path.

[0070] (c) The signal return light is filtered out by the aperture 13 to remove the approximately annular fractional vortex reflected light, retaining the central scattered light, and is then detected in dark field confocal by the focusing lens 14, pinhole 15 and photomultiplier tube 16.

[0071] (d) The measured electrical signal is input to the lock-in amplifier 17 , which demodulates the measured electrical signal according to the reference signal provided by the function generator 18 to obtain the measurement information of the sample 11 to be measured.

[0072] In this embodiment, when a certain scanning point has no defects, there is a fixed difference in the return signal intensity under the illumination of the l1 and l2 order vortex light, and the demodulation amplitude of the phase-locked amplifier 17 is a non-zero basis; when a certain scanning point has a defect, the difference in the return signal intensity under the illumination of the l1 and l2 order vortex light increases, and the demodulation amplitude and phase of the phase-locked amplifier 17 both show significant changes, thereby obtaining the defect distribution of the sample to be tested 11. Therefore, when the present embodiment uses the phase-locked amplifier 17 to demodulate the measurement electrical signal, it can be judged whether each scanning point has defects based on the demodulation amplitude and phase of the phase-locked amplifier 17. Specifically, when the demodulation amplitude of the phase-locked amplifier 17 is a non-zero basis, it is determined that the current scanning point has no defects. When the demodulation amplitude and phase of the phase-locked amplifier 17 both float significantly, it is determined that the current scanning point has defects, and finally the defect distribution of the sample to be tested 11 can be obtained.

[0073] (e) The sample stage can use an axial electric translation stage 12, and the light beam is optically scanned by the galvanometer 7. Each scanning point obtains an amplitude voltage for demodulation by the phase-locked amplifier 17. After the light beam scans in the sample to be tested 11, a two-dimensional image is obtained.

[0074] In this embodiment, the fractional-order vortex light performs a point scanning process on the surface of the sample to be measured 11, and the dwell time of each scanning point is greater than 2-3 times the phase switching period.

[0075] (f) The axial electric translation stage 12 performs a step-by-step displacement motion, recording a two-dimensional image for each step. After the measurement is completed, a three-dimensional image of the sample 11 to be measured can be achieved.

[0076] To make the specific measurement process of the device of the present application clearer, an example is provided below. In actual use, it is necessary to pre-load two different fractional-order vortex phase images into the spatial light modulator 5, one of which has a vortex phase order of 0.8 and the other has a vortex phase order of 1.2. Then, the function generator 18 is controlled by program setting to generate a trigger signal of 1.5kHz, and the spatial light modulator 5 is controlled to switch rapidly between two fractional-order vortex phase images at a speed of 1.5kHz; then, the spatial light modulator 5 is placed in the illumination light path of the time-varying modulation illumination module, and the polarization state of the incident light of the laser 1 is modulated by the half-wave plate 2 and the polarizer 3 to match the spatial light modulator 5, and irradiated on the spatial light modulator 5 to obtain fractional-order vortex light with a phase rapidly switching between 0.8 order and 1.2 order; then, the fractional-order vortex light is guided to the surface of the sample to be tested 11 through the optical scanning module, so that the fractional-order vortex light passes through the second non-polarization beam splitter 6, the galvanometer 7, the scanning lens 8, the tube lens 9 and the objective lens 10 in sequence and is irradiated on the surface of the sample to be tested 11, and the sample to be tested 11 is scanned and detected by the galvanometer 7, and the return light signal intensity at the point of the sample to be tested 11 is recorded for each scan, and the residence time of the light spot of a single scanning point is set to 2ms, and its return light signal passes through the objective lens 1 in sequence. 0, the tube lens 9, the scanning lens 8, the galvanometer 7 and the second non-polarizing beam splitter 6 return to the original path and reach the signal acquisition and demodulation module. After the aperture 13 of the signal acquisition and demodulation module receives the return light signal transmitted by the second non-polarizing beam splitter 6, it filters the return light signal and retains the central scattered light signal. The central scattered light signal is focused to the pinhole 15 by the focusing lens 14. The photomultiplier tube 16 collects the central scattered light signal and converts it into a measurement electrical signal; finally, the measurement electrical signal is input to the phase-locked amplifier 17. The function generator 18 provides the phase-locked amplifier 17 with a reference signal with a frequency of 1.5kHz. The phase-locked amplifier 17 demodulates the measurement electrical signal according to the reference signal. When the demodulation amplitude of the phase-locked amplifier 17 is a non-zero base, it is determined that there is no defect at the current scanning point. When the demodulation amplitude and phase of the phase-locked amplifier 17 are obviously floating, it is determined that there is a defect at the current scanning point, thereby determining whether there are defects at each position point of the sample to be tested 11, and further obtaining the defect distribution of the sample to be tested 11.

[0077] This embodiment utilizes time-varying fractional-order vortex light illumination to highlight the scattered information of the sample 11 under test, increasing the signal strength of tiny defects and thereby improving the device's defect detection sensitivity. Furthermore, the lock-in amplifier 17 utilizes its high-sensitivity demodulation capability for tiny periodically varying signals to detect the weak intensity and phase fluctuations caused by defects with high sensitivity, further enhancing the device's defect detection sensitivity.

[0078] Another embodiment of the present application provides a dark field confocal microscopy measurement method based on time-varying fractional-order vortex demodulation, which is applied to the dark field confocal microscopy measurement device based on time-varying fractional-order vortex demodulation as described in the above embodiment. Figure 2 and Figure 3 As shown, the dark field confocal microscopy measurement method based on time-varying fractional-order vortex demodulation mainly includes the following steps.

[0079] Step S1: emitting fractional-order vortex light to an optical scanning module using a time-varying modulation illumination module.

[0080] Step S2: using the optical scanning module to transmit the fractional-order vortex light to the sample 11 to be tested in the sample stage; when the fractional-order vortex light reflects an echo signal on the sample 11 to be tested, the echo signal is transmitted to the signal acquisition and demodulation module.

[0081] Step S3, using the signal acquisition and demodulation module to collect the return light signal, and performing dark field confocal detection on the return light signal according to the reference signal to obtain measurement information of the sample to be tested 11, wherein the measurement information is the measurement result of whether the sample to be tested 11 has defects based on dark field confocal detection.

[0082] In this embodiment, step S1 utilizes the time-varying modulation illumination module to emit fractional-order vortex light to the optical scanning module, which specifically includes the following contents.

[0083] Step S11 : Utilize the laser 1 to emit incident light, and the incident light sequentially passes through the half-wave plate 2 , the polarizer 3 , and the first non-polarization beam splitter 4 before reaching the spatial light modulator 5 .

[0084] Step S12: Utilize the spatial light modulator 5 to modulate the incident light into the fractional-order vortex light according to a reference signal, and transmit the fractional-order vortex light to the first non-polarization beam splitter 4.

[0085] Step S13: The first non-polarization beam splitter 4 transmits the fractional-order vortex light to the optical scanning module.

[0086] In this embodiment, step S2 uses the optical scanning module to transmit the fractional-order vortex light to the sample to be tested 11 in the sample stage. When the fractional-order vortex light reflects an echo signal on the sample to be tested 11, the echo signal is transmitted to the signal acquisition and demodulation module, which specifically includes the following contents.

[0087] Step S21: Use the second non-polarizing beam splitter 6 to receive the fractional-order vortex light emitted from the first non-polarizing beam splitter 4, and transmit the fractional-order vortex light to the galvanometer 7, scanning lens 8, tube lens 9 and objective lens 10 in sequence, and then irradiate it onto the sample to be tested 11 in the sample stage.

[0088] Step S22 : using the objective lens 10 to receive the return light signal reflected by the sample 11 to be tested, and transmitting the return light signal to the tube lens 9 , the scanning lens 8 and the galvanometer mirror 7 in sequence, and then reaching the second non-polarization beam splitter 6 .

[0089] Step S23: using the second non-polarization beam splitter 6 to transmit the return light signal to the signal acquisition and demodulation module.

[0090] In this embodiment, step S3 utilizes the signal acquisition and demodulation module to acquire the return light signal, and performs dark field confocal detection on the return light signal according to the reference signal to obtain measurement information of the sample to be measured 11, which specifically includes the following contents.

[0091] Step S31 : using the aperture 13 to receive the return light signal transmitted by the second non-polarization beam splitter 6 , and filtering the return light signal to obtain a central scattered light signal.

[0092] Step S32 : Using the focusing lens 14 to focus the central scattered light signal onto the pinhole 15 , the central scattered light signal passes through the pinhole 15 and is transmitted to the photomultiplier tube 16 .

[0093] Step S33 : using the photomultiplier tube 16 to convert the central scattered light signal into an electrical signal, and transmitting the electrical signal to the lock-in amplifier 17 .

[0094] Step S34 : Demodulate the electrical signal using the lock-in amplifier 17 according to the reference signal to obtain measurement information of the sample 11 to be tested.

[0095] The present application proposes a dark-field confocal microscopy measurement device and method based on time-varying fractional-order vortex demodulation, which uses fractional-order vortex light with rapidly switched orders as incident light to scan the sample 11 to be measured, distinguishes surface reflection information from interlayer defect scattering information through orbital angular momentum, and uses the asymmetric change of scattering information during rapid phase switching to highlight defect signals, and uses a phase-locked amplifier 17 to demodulate and obtain high-sensitivity sample information, thereby being able to measure and capture nanometer-level measurement information of the sample 11 to be measured, and can more accurately and reliably identify defects in the sample 11 to be measured, thereby improving the accuracy of defect detection and the defect recognition rate of the dark-field confocal microscopy measurement device.

[0096] The technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0097] This document uses specific examples to illustrate the principles and implementation methods of this application. The description of the above examples is only intended to help understand the method and core concept of this application. At the same time, for those skilled in the art, based on the concept of this application, there may be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A dark field confocal microscopy measurement device based on time-varying fractional-order vortex demodulation, characterized in that: The dark field confocal microscopy measurement device based on time-varying fractional-order vortex demodulation includes a time-varying modulation illumination module, an optical scanning module, a signal acquisition and demodulation module, a function generator and a sample stage, wherein the function generator is connected to the time-varying modulation illumination module and the signal acquisition and demodulation module respectively; The function generator is used to provide reference signals for the time-varying modulation lighting module and the signal acquisition and demodulation module respectively; The reference signal frequency provided by the function generator to the time-varying modulation lighting module and the signal acquisition and demodulation module is the same; The sample stage is used to place the sample to be tested; The time-varying modulation illumination module is used to emit fractional-order vortex light to the optical scanning module; The time-varying modulated illumination module comprises a laser, a half-wave plate, a polarizer, a first non-polarizing beam splitter and a spatial light modulator which are arranged in sequence, and the spatial light modulator is connected to the function generator; The laser emits incident light, and the incident light passes through the half-wave plate, the polarizer, and the first non-polarizing beam splitter in sequence before reaching the spatial light modulator. The spatial light modulator quickly switches between two fractional-order vortex phase images according to the reference signal. The phase distributions of the two fractional-order vortex phase images are respectively the superposition of exp(il1φ) and exp(il2φ) and the same blazed grating, wherein φ is the angular coordinate of the liquid crystal surface of the spatial light modulator, l1 and l2 are orders, satisfying 1-l1=l2-1, |l1|>0.5, |l2|>0.5, the blazed grating period is M, the phase image is a grayscale image, the grayscale 0-255 linearly corresponds to 0-2π, the switching frequency is greater than 1kHz, and the incident light is modulated into the fractional-order vortex light, and the fractional-order vortex light is transmitted to the first non-polarizing beam splitter, and the first non-polarizing beam splitter transmits the fractional-order vortex light to the optical scanning module; The optical scanning module is used to transmit the fractional-order vortex light to the sample to be tested in the sample stage, and, when the fractional-order vortex light reflects a return light signal on the sample to be tested, transmit the return light signal to the signal acquisition and demodulation module; The optical scanning module includes a second non-polarizing beam splitter, which is arranged opposite to the first non-polarizing beam splitter; The signal acquisition and demodulation module is used to acquire the return light signal and perform dark field confocal detection on the return light signal according to the reference signal to obtain measurement information of the sample to be tested, wherein the measurement information is a measurement result of whether the sample to be tested has defects obtained based on the dark field confocal detection; The signal acquisition and demodulation module includes an aperture, a focusing lens, a pinhole, a photomultiplier tube and a phase-locked amplifier arranged in sequence; the focusing lens is arranged opposite to the second non-polarizing beam splitter, and the aperture is arranged between the focusing lens and the second non-polarizing beam splitter; the phase-locked amplifier is connected to the function generator; the aperture receives the return light signal transmitted by the second non-polarizing beam splitter, filters the return light signal, and retains the central scattered light signal. The central scattered light signal is focused to the pinhole by the focusing lens, and the photomultiplier tube converts the central scattered light signal into an electrical signal, and then transmits the electrical signal to the phase-locked amplifier. The phase-locked amplifier demodulates the electrical signal according to the reference signal. The demodulation frequency of the phase-locked amplifier is the same as the frequency of the spatial light modulator switching the fractional-order vortex phase image, and the time constant is greater than 2-3 times the period of the reference signal, thereby obtaining the measurement information of the sample to be measured.

2. The dark field confocal microscopy measurement device based on time-varying fractional-order vortex demodulation according to claim 1, characterized in that: The optical scanning module further includes a galvanometer, a scanning lens, a tube lens and an objective lens arranged in sequence; The objective lens is arranged opposite to the sample stage; The second non-polarizing beam splitter receives the fractional-order vortex light emitted from the first non-polarizing beam splitter, and the fractional-order vortex light passes through the galvanometer, the scanning lens, the tube lens, and the objective lens in sequence, and then irradiates the sample to be measured in the sample stage; The objective lens receives the return light signal reflected by the sample to be tested, and transmits the return light signal to the tube lens, the scanning lens and the galvanometer in sequence before reaching the second non-polarizing beam splitter, and the second non-polarizing beam splitter transmits the return light signal to the signal acquisition and demodulation module.

3. The dark field confocal microscopy measurement device based on time-varying fractional-order vortex demodulation according to claim 1, characterized in that: The sample stage is an axial electric translation stage.

4. A dark field confocal microscopy measurement method based on time-varying fractional-order vortex demodulation, characterized in that: The dark-field confocal microscopy measurement method based on time-varying fractional-order vortex demodulation is applied to the dark-field confocal microscopy measurement device based on time-varying fractional-order vortex demodulation according to any one of claims 1 to 3, and the dark-field confocal microscopy measurement method based on time-varying fractional-order vortex demodulation includes: Using a time-varying modulation illumination module to emit fractional-order vortex light to an optical scanning module; The optical scanning module is used to transmit the fractional-order vortex light to the sample to be tested on the sample stage. When the fractional-order vortex light reflects a return light signal on the sample to be tested, the return light signal is transmitted to the signal acquisition and demodulation module. The signal acquisition and demodulation module is used to acquire the return light signal, and dark field confocal detection is performed on the return light signal according to the reference signal to obtain measurement information of the sample to be tested. The measurement information is a measurement result of whether the sample to be tested has defects based on dark field confocal detection.

5. The dark field confocal microscopy measurement method based on time-varying fractional-order vortex demodulation according to claim 4, characterized in that: The time-varying modulation illumination module is used to emit fractional-order vortex light to the optical scanning module, specifically including: Using a laser to emit incident light, the incident light passes through a half-wave plate, a polarizer, and a first non-polarizing beam splitter in sequence before reaching a spatial light modulator; modulating the incident light into the fractional-order vortex light according to a reference signal using the spatial light modulator, and transmitting the fractional-order vortex light to the first non-polarization beam splitter; The first non-polarization beam splitter transmits the fractional-order vortex light to the optical scanning module.

6. The dark field confocal microscopy measurement method based on time-varying fractional-order vortex demodulation according to claim 5, characterized in that: The optical scanning module is used to transmit the fractional-order vortex light to the sample to be tested on the sample stage. When the fractional-order vortex light reflects a return light signal on the sample to be tested, the return light signal is transmitted to the signal acquisition and demodulation module, which specifically includes: using a second non-polarizing beam splitter to receive the fractional-order vortex light emitted from the first non-polarizing beam splitter, and transmitting the fractional-order vortex light to a galvanometer, a scanning lens, a tube lens, and an objective lens in sequence, and then irradiating the fractional-order vortex light onto the sample to be measured in the sample stage; Using the objective lens to receive the return light signal reflected by the sample to be tested, and transmitting the return light signal to the tube lens, the scanning lens and the galvanometer mirror in sequence before reaching the second non-polarization beam splitter; The second non-polarization beam splitter is used to transmit the return light signal to the signal acquisition and demodulation module.

7. The dark field confocal microscopy measurement method based on time-varying fractional-order vortex demodulation according to claim 6, characterized in that: The signal acquisition and demodulation module is used to acquire the return light signal, and dark field confocal detection is performed on the return light signal according to the reference signal to obtain measurement information of the sample to be measured, specifically including: receiving the return light signal transmitted by the second non-polarization beam splitter by using an aperture, and filtering the return light signal to obtain a central scattered light signal; Focusing the central scattered light signal onto a pinhole using a focusing lens, so that the central scattered light signal passes through the pinhole and is transmitted to a photomultiplier tube; Converting the central scattered light signal into an electrical signal using the photomultiplier tube, and transmitting the electrical signal to a lock-in amplifier; The lock-in amplifier is used to demodulate the electrical signal according to a reference signal to obtain measurement information of the sample to be measured.

8. The dark field confocal microscopy measurement method based on time-varying fractional-order vortex demodulation according to claim 4 is characterized in that: The sample stage is an axial electric translation stage.

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