Phase-differential coherent Fourier scattering surface particle detection device and method

Abstract

The present invention proposes a phase-differential coherent Fourier scattering surface particle detection device and method, which belongs to the technical field of flexible substrate surface particle detection and solves the problem of low sensitivity in nanometer-scale particle detection under low illumination power conditions in the visible light band. The detection device includes: a laser, a collimating lens, a first aperture, a polarization state modulation module, a first beam splitter prism, a plane reflector, a piezoelectric driver, an infinity-corrected microscope objective lens, a sample, a three-dimensional piezoelectric scanning stage, a two-dimensional coarse adjustment displacement stage, a second beam splitter prism, a tube lens, a camera, a wide-field illumination light source, a second aperture, a first lens, a third aperture, a second lens, a two-quadrant photodetector, a weak signal amplification circuit, a data acquisition module, and a computer control system.

Description

Technical Field

[0001] The invention relates to a phase-differential coherent Fourier scattering surface particle detection device and method, belonging to the technical field of flexible substrate surface particle detection. Background Art

[0002] During the manufacturing process of high-performance flexible integrated circuits, impurities such as dust and particulate matter can land on the surface of flexible substrates or packaging films, leading to defects such as pinholes and cracks. These impurities can create pathways for oxygen and water vapor to pass through, severely degrading the functionality and stability of flexible electronic devices. As the performance of flexible chips improves, flexible substrate surface particle detection technology has become a key component in improving the yield rate of flexible device manufacturing.

[0003] Different from traditional silicon-based substrates, the "light, thin, and transparent" characteristics of flexible substrates put forward new demands on surface particle detection technology. Among them, some organic compound substrate materials have strong absorption of light ≤400nm, thus limiting the detection wavelength range to the visible light band >400nm; in addition, flexible substrates are more susceptible to thermal damage due to irradiation with detection light, so the detection light power should be strictly controlled; as the single-layer thickness of flexible substrate materials decreases to tens of nanometers, the particle detection sensitivity requirements also increase to tens of nanometers. Traditional surface particle detection technology for unpatterned wafers (silicon substrates) based on dark-field scattering often relies on high-power illumination and short-wavelength ultraviolet light when detecting particles of tens of nanometers, which is not suitable for flexible substrate materials. In other words, surface particle detection technology applied to silicon-based substrates is difficult to directly apply to flexible substrates.

[0004] Therefore, a key technical problem that urgently needs to be solved in this field is: how to achieve high-sensitivity detection of nanoparticles under low illumination power conditions in the visible light band and improve the yield rate of flexible chip manufacturing. Summary of the Invention

[0005] In order to solve the problem of low sensitivity in detecting nano-sized particles under low illumination power conditions in the visible light band, the present invention proposes a surface particle detection device and method using phase-differential coherent Fourier scattering, wherein the detection device comprises:

[0006] Laser (1), collimating lens (2), first aperture (3), polarization state modulation module (4), first beam splitter prism (5), plane reflector (6), piezoelectric driver (7), infinity correction microscope objective lens (8), sample (9), three-dimensional piezoelectric scanning stage (10), two-dimensional coarse adjustment displacement stage (11), second beam splitter prism (12), tube lens (13), wide field illumination light source (14), second aperture (15), third beam splitter prism (16), camera (17), first lens (18), third aperture (19), second lens (20), two-quadrant photodetector (21), weak signal amplification circuit (22), data acquisition module (23), computer control system (24).

[0007] Preferably, the two-quadrant photodetector (21) is located in a conjugate plane of the back focal plane of the infinity-corrected microscope objective (8).

[0008] Preferably, the wide-field illumination source (14) and the camera (17) are located in the focal plane of the tube lens (13).

[0009] A phase-differential coherent Fourier scattering surface particle detection method, comprising:

[0010] Step 1: Turn on the wide-field illumination light source (14), and emit the light through the tube lens (13) after being reflected by the second aperture (15) and the third beam splitter prism (16). The emitted light is reflected by the second beam splitter prism (12) and transmitted by the first beam splitter prism (5) before entering the infinity-corrected microscope objective lens (8) for focusing, thereby realizing wide-field illumination of the sample (9). Set a camera (17) to image the sample (9) so that the sample (9) is located at the focal plane of the infinity-corrected microscope objective lens (8). According to the imaging result, adjust the position of the sample (9) through the two-dimensional coarse adjustment stage (11) until the surface area to be detected of the sample (9) is located at the center of the field of view.

[0011] Step 2: Turn off the wide-field illumination light source (14), turn on the laser (1), and the laser light emitted by the laser (1) passes through the collimating lens (2), the first aperture (3) and the polarization state modulation module (4) and is reflected and transmitted by the first beam splitter prism (5). The light transmitted by the first beam splitter prism (5) is irradiated onto the surface of the plane reflector (6) controlled by the piezoelectric driver (7) for reflection. The light reflected by the first beam splitter prism (5) is passed through the infinity-corrected microscope objective (8) to realize bright-field coherent point illumination of the sample (9). The position of the sample (9) is adjusted so that the sample (9) is strictly located on the focal plane of the infinity-corrected microscope objective (8);

[0012] Step 3: The bright field coherent illumination light is focused by the infinity-corrected microscope objective (8), and the spot undergoes mirror reflection, particle scattering, and scattering-reflection interaction with the surface of the sample (9). The signal light carrying the sample surface information collected by the infinity-corrected microscope objective (8) is transmitted through the first beam splitter prism (5) and interferes with the reference light from the plane reflector (6) reflected by the first beam splitter prism (5). The interference light is reflected by the second beam splitter prism (12) and focused by the tube lens (13) to the plane where the camera (17) is located, so that the camera (17) detects the imaging point on the surface of the sample (9) to ensure in real time that the sample (9) is located in the focal plane of the infinity-corrected microscope objective (8);

[0013] Step 4: The interference light transmitted by the second beam splitter (12) is focused by the first lens (18) and filtered by the third aperture (19) before being emitted by the second lens (20). A two-quadrant photodetector (21) is placed at a conjugate plane of the rear focal plane of the infinity-corrected microscope objective (8) to collect interference signals of reflected light, particle scattered light, and scattered reflected light and reference light in the far field, thereby detecting the signal generated by the interaction between the sample (9) and the high numerical aperture illumination spot.

[0014] Step 5: The two intensity signals detected by the two-quadrant photoelectric detector (21) are respectively input into the weak signal amplification circuit (22) for weak signal amplification and then input into the data acquisition module (23), and then input into the computer control system (24) through the data acquisition module (23), and the phase difference between the two photoelectric signals is calculated by the phase difference measurement program in the computer control system (24);

[0015] Step 6: Move the sample (9) so that the scanning starting point is located at a position where there are no particles on the surface, and fine-tune the position of the two-quadrant photodetector (21) so that the far-field phase difference measurement value is 0, so as to ensure that the center of the light beam carrying the surface information of the sample (9) coincides with the center of the two-quadrant photodetector (21);

[0016] Step 7: The computer control system (24) drives the three-dimensional piezoelectric scanning stage (10) to scan the sample (9) in the XY direction, controls the oscillation period and amplitude of the piezoelectric driver (7) to achieve continuous modulation of the reference light phase, records the phase difference measurement value of each scanning position, and constructs a phase difference measurement value image of the complete scanning area by reading the scanning data line by line;

[0017] Step 8: Based on the phase difference measurement value image, the position and size of the particles are determined by the peak positioning algorithm and the particle size estimation algorithm, and a defect detection result report of the sample (9) is constructed, wherein the particle position is determined by the zero-crossing position between the peak-valley / valley-peak signals found by the peak positioning algorithm, and the particle size estimation is determined by the pixel area occupied by the peak-valley / valley-peak signal or the peak-to-peak value.

[0018] Preferably, in step 1, the wide-field illumination light source (14) is a white light source, and the infinity-corrected microscope objective lens (8) is a high numerical aperture infinity-corrected microscope objective lens with NA≥0.6.

[0019] Preferably, the wavelength of the laser emitted by the laser (1) in step 2 is limited to the visible light band, and the wavelength is one of 405 nm and 633 nm.

[0020] Preferably, the polarization state generated by the polarization state modulation module (4) in step 2 is one of linear polarization and radial polarization.

[0021] Preferably, in step 3, the illumination power generated by the spot of the bright field coherent illumination light after being focused by the infinity-corrected microscope objective lens (8) is less than 1 mW.

[0022] Preferably, the arrangement of the two photosensitive surfaces of the two-quadrant photodetector (21) in step 5 is the same as the main scanning direction, the main scanning direction is defined as a direction in which each scan is greater than 1 step along the far-field phase signal scanning direction, and the sub-scanning direction is defined as a direction in which each step is only 1 step along the far-field phase signal scanning direction. If the main scanning direction is the X direction, the two photosensitive surfaces are arranged along the X direction, and the far-field intensity signal carrying the surface information is divided into two photoelectric signals of the left and right quadrants.

[0023] Preferably, the scanning spacing of the sample (9) in the XY direction in step 7 is determined by the minimum particle size of the surface of the sample (9) to be detected, the scanning mode is one of serpentine scanning and grating scanning, and the modulation mode of the reference light phase is sinusoidal modulation.

[0024] The beneficial effects of the present invention are:

[0025] The phase-differential coherent Fourier scattering surface particle detection method provided by the present invention detects the far-field phase-differential signal after the interaction between the sample surface and the high numerical aperture focused light spot. Since the phase signal is more sensitive to surface height changes than the intensity signal, the detection sensitivity based on the far-field phase-differential signal is significantly better than the intensity / amplitude detection method. The bright field illumination and detection method can significantly reduce the illumination light power required for detection. By controlling the splitting ratio of the reference light and the signal light, the interference amplification of the signal light can be achieved. Therefore, the present invention can achieve higher sensitivity detection in the visible light band with low illumination power. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the structure of a phase-differential coherent Fourier scattering surface particle detection device provided by the present invention. Figure 1Among them, 1-laser; 2-collimating lens; 3-first aperture; 4-polarization state modulation module; 5-first beam splitter prism; 6-plane mirror; 7-piezoelectric driver; 8-infinity-corrected microscope objective; 9-sample; 10-3D piezoelectric scanning stage; 11-2D coarse adjustment stage; 12-second beam splitter prism; 13-tube lens; 14-widefield illumination source; 15-second aperture; 16-third beam splitter prism; 17-camera; 18-first lens; 19-third aperture; 20-second lens; 21-two-quadrant photodetector; 22-weak signal amplification circuit; 23-data acquisition module; 24-computer control system;

[0027] Figure 2 A schematic diagram of the process of a phase-differential coherent Fourier scattering surface particle detection method provided by the present invention;

[0028] Figure 3 This is a schematic diagram of scanning the sample area to be tested provided by the present invention. Figure 3 In the figure, (a) is a schematic diagram of surface reflection when there are no particles on the surface, and (b) is a schematic diagram of surface reflection, particle scattering, and scattering-reflection when there are particles on the surface;

[0029] Figure 4 This is a comparison diagram of the far-field phase difference signal and intensity difference signal of particles with a diameter of 100 nm provided by the present invention. DETAILED DESCRIPTION

[0030] Specific implementation method 1: Combination Figure 1 This embodiment describes a phase-difference coherent Fourier scattering surface particle detection device, which includes:

[0031] Laser 1, collimating lens 2, first aperture 3, polarization state modulation module 4, first beam splitter prism 5, plane reflector 6, piezoelectric driver 7, infinity-corrected microscope objective 8, sample 9, three-dimensional piezoelectric scanning stage 10, two-dimensional coarse adjustment stage 11, second beam splitter prism 12, tube lens 13, wide-field illumination light source 14, second aperture 15, third beam splitter prism 16, camera 17, first lens 18, third aperture 19, second lens 20, two-quadrant photodetector 21, weak signal amplification circuit 22, data acquisition module 23 and computer control system 24, wherein the two-quadrant photodetector 21 is located in a conjugate plane of the rear focal plane of the infinity-corrected microscope objective 8, and the wide-field illumination light source 14 and the camera 17 are located in the focal plane of the tube lens 13.

[0032] The laser light emitted by the laser 1 is collimated by the collimating lens 2 and the beam diameter is controlled by the first aperture 3. After passing through the polarization state modulation module 4, it generates linearly polarized light or radially polarized light, forming a coherent illumination beam. The coherent light beam is reflected by the first beam splitter prism 5 and enters the infinity-corrected microscope objective 8. After transmission, it irradiates the surface of the plane reflector 6 controlled by the piezoelectric driver 7. The light reflected by the first beam splitter prism 5 produces a tightly focused light spot at the focal plane of the infinity-corrected microscope objective 8. The white light generated by the wide-field illumination light source 14 is reflected by the second aperture 15 and the third beam splitter prism 16 and then emitted by the tube lens 13. The emitted parallel light is reflected by the second beam splitter prism 12 and transmitted by the first beam splitter prism 5. It is then focused by the infinity-corrected microscope objective 8, producing a wide-field illumination spot at the focal plane of the infinity-corrected microscope objective 8. Turn on the wide-field illumination light source 14 and turn off the laser 1, adjust the two-dimensional coarse adjustment stage 11, the three-dimensional piezoelectric scanning stage 10 and the observation camera 17, so that the area to be measured of the sample 9 is placed in the field of view and strictly placed on the focal plane of the infinity-corrected microscope objective 8; turn off the wide-field illumination light source 14 and turn on the laser 1, fine-tune the three-dimensional piezoelectric scanning stage again and observe the camera 17, so that the sample is strictly located on the focal plane of the infinity-corrected microscope objective 8; set the scanning starting position to a position on the surface of the area to be measured where there are no particles, and the laser light emitted by the laser 1 is tightly focused by the infinity-corrected microscope objective 8 to produce a light spot on the surface where there are no particles. At this time, the sample 9 interacts with the light spot produced by the tight focus of the infinity-corrected microscope objective 8, and the reflected light on the surface of the sample 9 is collected by the infinity-corrected microscope objective 8 to form signal light carrying information about the sample surface. The signal light interferes with the reflected light from the plane reflector 6 at the first beam splitter prism 5, and the Fourier plane detection optical path constructed by the first lens 18 and the second lens 20 records the interference signal of the far field of the two quadrants. Specifically, the light beam carrying the object plane information emitted by the infinity-corrected microscope objective 8 is transmitted through the first beam splitter prism 5 and interferes with the reference light from the plane reflector 6 reflected by the first beam splitter prism 5. The interference light is imaged on the plane where the third aperture 19 is located by the first lens 18, and the front focal plane of the second lens 20 coincides with the plane where the third aperture 19 is located. The interference light beam carrying the object plane information is filtered by the third aperture 19 and emitted by the second lens 20. The two-quadrant photodetector 21 is placed on the back focal plane of the second lens 20, which is a conjugate plane of the back focal plane of the infinity-corrected microscope objective 8. The two beams of photoelectric signals detected by the two-quadrant photodetector 21 are respectively input into the weak signal amplification circuit 22 for signal amplification. The output signal of the weak signal amplification circuit 22 is the input of the data acquisition module 23. The output signal of the data acquisition module 23 is sent to the computer control system 24. The phase difference measurement program in the computer control system 24 realizes the measurement of the phase difference between the two photoelectric signals.Since the current position is located at a particle-free surface, the phase difference measurement result should be approximately 0. Therefore, the position of the two-quadrant photodetector 21 is fine-tuned according to the current phase difference measurement result until the phase difference measurement result is approximately 0, ensuring that the light beam emitted by the second lens 20 is incident on the center of the two-quadrant photodetector 21. The computer control system 24 controls the oscillation frequency and amplitude of the piezoelectric driver 7 and simultaneously drives the three-dimensional piezoelectric scanning stage 8 to complete line-by-line scanning of the test area of ​​the sample 9. During scanning, the phase difference measurement value of each scanning position is recorded, and the phase difference measurement result of the entire test area is constructed by splicing the line-by-line data. When the focused beam from infinity-corrected microscope objective 8 passes through a particle located on the surface of sample 9, the phase signals of the left and right quadrants of the two-quadrant photodetector 21 will differ significantly. The phase difference signal will exhibit a peak followed by a valley, or a valley followed by a peak. When the center of the focused beam coincides with the center of the particle, assuming the particle is a perfect sphere, the phase effect of the left side of the particle on the left quadrant signal is the same as the effect of the right side of the particle on the right quadrant signal. At this point, the phase difference measurement value is zero, and the particle center coincides with the center of the beam, which can be used to determine the position of the particle center. Therefore, the phase difference measurement result for the entire test area is a peak-valley signal appearing in a background signal that is approximately zero. The particle size can be determined based on the duration or amplitude of the peak-valley signal. Therefore, the phase difference measurement results for the entire test area are used to determine the position and size of the particle using a peak location algorithm and a particle size estimation algorithm, thereby obtaining a defect detection report for sample 9.

[0033] Specific implementation method 2: Combination Figure 2-4 This embodiment is described as follows. Figure 2 As shown, the steps of a phase-differential coherent Fourier scattering surface particle detection method described in this embodiment include:

[0034] S1: Turn on the wide-field illumination light source and adjust the sample position so that the area to be inspected is in the center of the field of view;

[0035] Turn on the wide-field illumination light source 14. After being reflected by the second aperture 15 and the third beam splitter prism 16, the light is emitted from the tube lens 13. The emitted light is reflected by the second beam splitter prism 12 and transmitted by the first beam splitter prism 5 before entering the infinity-corrected microscope objective 8 for focusing, thereby achieving wide-field illumination of the sample 9. Set up a camera 17 to image the sample 9 so that the sample 9 is located in the focal plane of the infinity-corrected microscope objective 8. Based on the imaging results, adjust the position of the sample 9 using the two-dimensional coarse adjustment stage 11 until the surface area of ​​the sample 9 to be inspected is located in the center of the field of view.

[0036] In S1 , the wide-field illumination light source 14 is a white light source, and the infinity-corrected microscope objective lens 8 is a high numerical aperture infinity-corrected microscope objective lens with NA ≥ 0.6.

[0037] S2: Turn off the widefield illumination source, turn on the laser, and adjust the sample position so that the sample is strictly located in the focal plane of the infinity-corrected microscope objective;

[0038] Turn off the wide-field illumination light source 14 and turn on the laser 1. The laser light emitted by the laser 1 passes through the collimating lens 2, the first aperture 3, and the polarization state modulation module 4, and is then reflected and transmitted by the first beam splitter prism 5. The light transmitted by the first beam splitter prism 5 is irradiated by the surface of the plane reflector 6 controlled by the piezoelectric driver 7 and reflected. The light reflected by the first beam splitter prism 5 is illuminated by the infinity-corrected microscope objective 8 to achieve bright-field coherent point illumination of the sample 9. The position of the sample 9 is adjusted so that the sample is strictly located on the focal plane of the infinity-corrected microscope objective 8.

[0039] The wavelength of the laser emitted by the laser 1 in S2 is limited to the visible light band, and the wavelength is one of 405 nm and 633 nm. The polarization state generated by the polarization state modulation module 4 is one of linear polarization and radial polarization.

[0040] S3: Through the interaction of specular reflection, particle scattering, and scattering-reflection with the reference light, the camera detects the imaging point on the sample surface, ensuring that the camera is located at the focal plane of the infinity-corrected microscope objective lens;

[0041] like Figure 3 As shown in (b), the bright field coherent illumination light is focused by the infinity-corrected microscope objective 8, and the spot undergoes specular reflection, particle scattering, and scattering-reflection interaction with the surface of the sample 9. The light carrying the sample surface information is collected by the infinity-corrected microscope objective 8 and transmitted by the first beam splitter prism 5, interfering with the reference light from the plane reflector 6 reflected by the first beam splitter prism 5. The interference light is focused by the tube lens 13 to the plane where the camera 17 is located, enabling the camera 17 to detect the imaging point on the surface of the sample 9 to ensure in real time that the camera 17 is located in the focal plane of the infinity-corrected microscope objective 8;

[0042] The illumination power generated by the spot of the bright field coherent illumination light in S3 after being focused by the infinity-corrected microscope objective 8 is less than 1 mW.

[0043] S4: Detecting the signal generated by the interaction between the sample and the high numerical aperture illumination spot;

[0044] After the light carrying the surface information of the sample 9 interferes with the reference light, it is transmitted by the second beam splitter prism 12, focused by the first lens 18, filtered by the third aperture 19, and emitted by the second lens 20. A two-quadrant photodetector 21 is placed in a conjugate plane of the rear focal plane of the infinity-corrected microscope objective 8 to collect the interference signals of the reflected light, the scattered light of the particles, and the scattered-reflected light and the reference light in the far field, thereby detecting the signal generated by the interaction between the sample 9 and the high numerical aperture illumination spot;

[0045] S5: Use a two-quadrant photoelectric detector to collect the far-field intensity signal and input it into a weak signal amplification circuit to amplify the two far-field intensity signals, and calculate the phase difference between the two photoelectric signals through a computer control system;

[0046] The two far-field intensity signals detected by the two-quadrant photodetector 21 are respectively input into the weak signal amplification circuit 22 for weak signal amplification and then input into the data acquisition module 23, and then input into the computer control system 24 through the data acquisition module 23. The phase difference of the two photoelectric signals is calculated by the phase difference measurement program in the computer control system 24;

[0047] The arrangement of the two photosensitive surfaces of the two-quadrant photodetector 21 in S5 is the same as the main scanning direction. The main scanning direction is defined as the direction in which each scan is greater than 1 step along the far-field phase signal scanning direction, and the sub-scanning direction is defined as the direction in which each step is only 1 step along the far-field phase signal scanning direction. If the main scanning direction is the X direction, the two photosensitive surfaces are arranged along the X direction, and the far-field intensity signal carrying the surface information is divided into two photoelectric signals, the left and right quadrants.

[0048] S6: Adjust the sample position so that the focused spot is located where there are no particles, and adjust the position of the two-quadrant photodetector so that the phase difference is 0;

[0049] like Figure 3 As shown in (a), the sample 9 is moved so that the scanning starting point is located at a position where there are no particles on the surface, and the position of the two-quadrant photodetector 21 is fine-tuned so that the far-field phase difference measurement value is 0, thereby ensuring that the center of the light beam carrying the surface information of the sample 9 coincides with the center of the two-quadrant photodetector 21;

[0050] S7: Modulate the phase of the reference light and scan the sample in the XY direction to construct a phase difference measurement value image of the scanned area;

[0051] The oscillation frequency and amplitude of the piezoelectric driver 7 are controlled by the computer control system 24 to achieve the modulation of the reference light phase. At the same time, the three-dimensional piezoelectric scanning stage 10 is driven to scan the sample 9 in the XY direction. The phase difference measurement value of each scanning position is recorded. The phase difference measurement value image of the complete scanning area is constructed by reading the scanning data line by line. The comparison of the far-field intensity difference signal and the phase difference signal of the particle with a diameter of 100nm is shown in FIG. Figure 4 As shown;

[0052] The modulation of the reference light phase in S7 may be sinusoidal modulation;

[0053] In S7, the scanning mode of the sample 9 in the XY direction is one of serpentine scanning and raster scanning, the X-direction scanning spacing is ≤ 1 / 40 of the focus spot diameter, and the Y-direction scanning spacing is 1 / 3-1 / 5 of the minimum particle size to be tested.

[0054] S8: Determine the position and size of the particles using a peak location algorithm and a particle size estimation algorithm;

[0055] Based on the phase difference measurement image, the peak location algorithm and particle size estimation algorithm are used to determine the position and size of the particles, and a defect detection result report is constructed;

[0056] The particle position measured in S8 is determined by the zero-crossing position between the peak-valley / valley-peak signals found by the peak positioning algorithm; the particle size estimation is determined by the pixel area occupied by the peak-valley / valley-peak signal or the peak-to-peak value.

[0057] In summary, the far-field phase difference signal after the interaction between the sample surface and the high numerical aperture focused light spot is detected. Since the phase signal is more sensitive to surface height changes than the intensity signal, the detection sensitivity based on the far-field phase difference signal is significantly better than the intensity / amplitude detection method. At the same time, the bright field illumination and detection method can significantly reduce the illumination light power required for detection. Therefore, the present invention can achieve higher sensitivity detection in the low illumination power visible light band.

[0058] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the present profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical content disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent replacement and improvement of the above embodiments made according to the technical essence of the present invention, within the spirit and principles of the present invention, without departing from the content of the technical solution of the present invention, shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A phase-differential coherent Fourier scattering surface particle detection method, characterized in that: The device used in the surface particle detection method includes: Laser (1), collimating lens (2), first aperture (3), polarization state modulation module (4), first beam splitter prism (5), plane reflector (6), piezoelectric driver (7), infinity correction microscope objective (8), sample (9), three-dimensional piezoelectric scanning stage (10), two-dimensional coarse adjustment stage (11), second beam splitter prism (12), tube lens (13), wide field illumination light source (14), second aperture (15), third beam splitter prism (16), camera (17), first lens (18), third aperture (19), second lens (20), two-quadrant photodetector (21), weak signal amplification circuit (22), data acquisition module (23), computer control system (24); The surface particle detection method comprises: Step 1: Turn on the wide-field illumination light source (14), which is reflected by the second aperture (15) and the third beam splitter prism (16) and then emitted from the tube lens (13). The emitted light is reflected by the second beam splitter prism (12) and transmitted by the first beam splitter prism (5) and then enters the infinity-corrected microscope objective lens (8) for focusing, thereby realizing wide-field illumination of the sample (9). Set the camera (17) to image the sample (9) so that the sample (9) is located in the focal plane of the infinity-corrected microscope objective lens (8). According to the imaging result, adjust the position of the sample (9) by the two-dimensional coarse adjustment stage (11) until the surface area to be detected of the sample (9) is located in the center of the field of view; Step 2: Turn off the wide-field illumination light source (14), turn on the laser (1), and the laser light emitted by the laser (1) passes through the collimating lens (2), the first aperture (3) and the polarization state modulation module (4) and is reflected and transmitted by the first beam splitter prism (5). The light transmitted by the first beam splitter prism (5) is irradiated onto the surface of the plane reflector (6) controlled by the piezoelectric driver (7) for reflection. The light reflected by the first beam splitter prism (5) is passed through the infinity-corrected microscope objective (8) to realize bright-field coherent point illumination of the sample (9). The position of the sample (9) is adjusted so that the sample (9) is strictly located on the focal plane of the infinity-corrected microscope objective (8); Step 3: The bright field coherent illumination light is focused by the infinity-corrected microscope objective (8), and the spot undergoes mirror reflection, particle scattering, and scattering-reflection interaction with the surface of the sample (9). The signal light carrying the sample surface information collected by the infinity-corrected microscope objective (8) is transmitted through the first beam splitter prism (5) and interferes with the reference light from the plane reflector (6) reflected by the first beam splitter prism (5). The interference light is reflected by the second beam splitter prism (12) and focused by the tube mirror (13) to the plane where the camera (17) is located, so that the camera (17) detects the imaging point on the surface of the sample (9) to ensure that the sample (9) is located in the focal plane of the infinity-corrected microscope objective (8) in real time. Step 4: The interference light transmitted by the second beam splitter (12) is focused by the first lens (18) and filtered by the third aperture (19) before being emitted by the second lens (20). A two-quadrant photodetector (21) is placed at a conjugate plane of the rear focal plane of the infinity-corrected microscope objective (8) to collect interference signals of reflected light, particle scattered light, and scattered reflected light and reference light in the far field, thereby detecting the signal generated by the interaction between the sample (9) and the high numerical aperture illumination spot. Step 5: The two far-field intensity signals detected by the two-quadrant photoelectric detector (21) are respectively input into the weak signal amplification circuit (22) for weak signal amplification and then input into the data acquisition module (23), and then input into the computer control system (24) through the data acquisition module (23), and the phase difference of the two photoelectric signals is calculated by the phase difference measurement program in the computer control system (24); Step 6: Move the sample (9) so that the scanning starting point is located at a position where there are no particles on the surface, and fine-tune the position of the two-quadrant photodetector (21) so that the far-field phase difference measurement value is 0, so as to ensure that the center of the light beam carrying the surface information of the sample (9) coincides with the center of the two-quadrant photodetector (21); Step 7: The computer control system (24) drives the three-dimensional piezoelectric scanning stage (10) to scan the sample (9) in the XY direction, controls the oscillation period and amplitude of the piezoelectric driver (7) to achieve continuous modulation of the reference light phase, and simultaneously records the phase difference measurement value of each scanning position. By reading the scanning data line by line, a phase difference measurement value image of the complete scanning area is constructed; Step 8: Based on the phase difference measurement value image, the position and size of the particles are determined by the peak location algorithm and the particle size estimation algorithm, and a defect detection result report of the sample (9) is constructed, wherein the particle position is determined by the zero-crossing position between the peak-valley / valley-peak signals found by the peak location algorithm, and the particle size estimation is determined by the pixel area occupied by the peak-valley / valley-peak signal or the peak-to-peak value.

2. The method for detecting surface particles using phase differential coherent Fourier scattering according to claim 1, wherein: The wide-field illumination source (14) and the camera (17) are located in the focal plane of the tube lens (13).

3. The method for detecting surface particles using phase differential coherent Fourier scattering according to claim 1, wherein: In step 1, the wide-field illumination light source (14) is a white light source, and the infinity-corrected microscope objective lens (8) is a high numerical aperture infinity-corrected microscope objective lens with NA ≥ 0.

6.

4. The method for detecting surface particles using phase differential coherent Fourier scattering according to claim 1, wherein: In step 2, the wavelength of the laser emitted by the laser (1) is limited to the visible light band, and the wavelength is one of 405 nm and 633 nm.

5. The method for detecting surface particles using phase differential coherent Fourier scattering according to claim 1, wherein: The polarization state generated by the polarization state modulation module (4) in step 2 is one of linear polarization and radial polarization.

6. The surface particle detection method using phase differential coherent Fourier scattering according to claim 1, characterized in that: In step 3, the illumination power generated by the spot of the bright field coherent illumination light after being focused by the infinity-corrected microscope objective (8) is less than 1 mW.

7. The method for detecting surface particles using phase differential coherent Fourier scattering according to claim 1, wherein: In step 5, the arrangement of the two photosensitive surfaces of the two-quadrant photodetector (21) is the same as the main scanning direction. The main scanning direction is defined as a direction in which each scan is greater than 1 step along the far-field phase signal scanning direction, and the sub-scanning direction is defined as a direction in which each step is only 1 step along the far-field phase signal scanning direction. If the main scanning direction is the X direction, the two photosensitive surfaces are arranged along the X direction, and the far-field intensity signal carrying the surface information is divided into two photoelectric signals of the left and right quadrants.

8. The method for detecting surface particles using phase differential coherent Fourier scattering according to claim 1, wherein: In step 7, the scanning spacing of the sample (9) in the XY direction is determined by the minimum particle size of the surface of the sample (9) to be detected, the scanning mode is one of serpentine scanning and grating scanning, and the modulation mode of the reference light phase is sinusoidal modulation.

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