Phase difference coherent Fourier scattering surface particle detection device and method

Abstract

The invention provides a phase difference coherent Fourier scattering surface particle detection device and method, belongs to the technical field of flexible substrate surface particle detection, and solves the problem of low nano-scale particle detection sensitivity under the condition of low illumination power of a visible light band. The detection device comprises a laser, a collimating lens, a first diaphragm, a polarization state modulation module, a first beam splitter prism, a plane mirror, a piezoelectric actuator, an infinite correction microscope objective, a sample, a three-dimensional piezoelectric scanning table, a two-dimensional coarse adjustment displacement table, a second beam splitter prism, a tube lens, a camera, a wide-field illumination light source, a second diaphragm, a first lens, a third diaphragm and a second lens. The system comprises a two-quadrant photoelectric detector, a weak signal amplification circuit, a data acquisition module and a computer control system.

Description

Technical Field

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

[0002] In the manufacturing process of high-performance flexible integrated circuits, dust, particle pollution and other impurities in the environment fall onto the surface of the flexible substrate or packaging film, which can easily lead to defects such as pinholes and cracks, providing transmission channels for oxygen, water vapor, etc., seriously reducing the function and stability of flexible electronic devices. With the improvement of flexible chip performance, flexible substrate surface particle detection technology has become a key guarantee for improving the manufacturing yield of flexible devices.

[0003] Different from traditional silicon-based substrates, the "light, thin, and transparent" characteristics of flexible substrates put forward new requirements for 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 of >400nm; in addition, flexible substrates are more susceptible to thermal damage due to detection light irradiation, 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. That is, the surface particle detection technology applied to silicon-based substrates is difficult to be directly applied 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 of flexible chip manufacturing. Summary of the invention

[0005] The present invention solves the problem of low sensitivity of nano-scale particle detection under low illumination power conditions in the visible light band, and further proposes a phase differential coherent Fourier scattering surface particle detection device and method, wherein the detection device comprises:

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

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

[0008] Preferably, the wide-field illumination light 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 after being reflected by the second aperture (15) and the third beam splitter prism (16), the light is emitted from the tube lens (13). After being reflected by the second beam splitter prism (12) and transmitted by the first beam splitter prism (5), the emitted light enters the infinity correction microscope objective lens (8) for focusing, thereby realizing wide-field illumination of the sample (9). A camera (17) is set to image the sample (9) so that the sample (9) is located in the focal plane of the infinity correction microscope objective lens (8). According to the imaging result, the position of the sample (9) is adjusted 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.

[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 then 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 then 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), and 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 the interference signals of the reflected light, the particle scattered light, and the scattered reflected light and the reference light in the far field, so as to detect 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 three-dimensional piezoelectric scanning stage (10) is driven by a computer control system (24) to scan the sample (9) in the XY direction, the oscillation period and amplitude of the piezoelectric driver (7) are controlled to achieve continuous modulation of the reference light phase, the phase difference measurement value of each scanning position is recorded, and a phase difference measurement value image of the complete scanning area is constructed 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 (8) is less than 1 mW.

[0022] Preferably, 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.

[0023] Preferably, in step 7, the scanning interval 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 method is one of serpentine scanning and grating scanning, and the modulation method 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 the surface height change 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, and the interference amplification of the signal light can be achieved by controlling the splitting ratio of the reference light and the signal light. 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 A schematic diagram of the structure of a phase-difference 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 reflector; 7-piezoelectric driver; 8-infinity-corrected microscope objective; 9-sample; 10-three-dimensional piezoelectric scanning stage; 11-two-dimensional coarse adjustment stage; 12-second beam splitter prism; 13-tube lens; 14-wide-field illumination light 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 a process flow of a phase-difference coherent Fourier scattering surface particle detection method provided by the present invention;

[0028] Figure 3 A schematic diagram of scanning the sample test area 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 is described. The structure of a phase-differential coherent Fourier scattering surface particle detection device described in this embodiment 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 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 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, and then the polarization state modulation module 4 generates linear polarized light or radial polarized light to form a coherent illumination beam. The coherent beam is reflected by the first beam splitter prism 5 and enters the infinity correction 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 generates a tightly focused light spot on the focal plane of the infinity correction 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, and then focused by the infinity correction microscope objective 8, and a wide-field illumination light spot is generated on the focal plane of the infinity correction 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 observe the camera 17, so that the area to be tested 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 start position to the position where there is no particle on the surface of the area to be tested, and the laser light emitted by the laser 1 is tightly focused by the infinity-corrected microscope objective 8. The spot is located at the surface without particles. At this time, the sample 9 interacts with the spot generated by the infinity-corrected microscope objective 8 after being tightly focused, and the reflected light on the surface of the sample 9 is collected by the infinity-corrected microscope objective 8 to form a signal light carrying the sample surface information. 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 through 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, and the two-quadrant photodetector 21 is placed on the rear focal plane of the second lens 20, which is the conjugate plane of the rear 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 amplifying circuit 22 for signal amplification. The output signal of the weak signal amplifying 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 at a surface without particles, 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, so as to ensure 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 drives the three-dimensional piezoelectric scanning stage 8 to complete the line-by-line scanning of the area to be tested of the sample 9. The phase difference measurement value of each scanning position is recorded while scanning, and the phase difference measurement result of the entire area to be tested is constructed by splicing the line-by-line data. When the focused light beam of the infinity-corrected microscope objective 8 passes through the particles on the surface of the sample 9, the phase signals of the left and right quadrants of the two-quadrant photodetector 21 will have obvious differences, and the phase difference signal will show a change of peak first and then valley or valley first and then peak. When the center of the focused light beam coincides with the center of the particle, assuming that the particle is an ideal sphere, the phase influence of the left side of the particle on the left quadrant signal is the same as the influence of the right side of the particle on the right quadrant signal. At this time, the phase difference measurement value is 0 and the center of the particle coincides with the center of the light beam, based on which the position of the center of the particle can be determined. Therefore, the phase difference measurement result of the entire area to be tested is a peak-valley signal appearing in a background signal that is approximately 0. The particle size can be determined based on the duration or amplitude of the peak-valley signal. Therefore, the defect detection report of sample 9 can be obtained by determining the position and size of the particle through the peak location algorithm and the particle size estimation algorithm for the phase difference measurement result of the entire area to be tested.

[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 tested is located in the center of the field of view;

[0035] The wide-field illumination light source 14 is turned on, and the light is emitted from 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, and then enters the infinity-corrected microscope objective 8 for focusing, so as to realize wide-field illumination of the sample 9. The camera 17 is set to image the sample 9 so that the sample 9 is located in the focal plane of the infinity-corrected microscope objective 8. According to the imaging result, the position of the sample 9 is adjusted by the two-dimensional coarse adjustment stage 11 until the surface area of ​​the sample 9 to be detected 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 an infinity-corrected microscope objective lens with a high numerical aperture of 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] The wide-field illumination light source 14 is turned off, and the laser 1 is turned on. 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 then is reflected and transmitted by the first beam splitter prism 5. The light transmitted by the first beam splitter prism 5 is irradiated to 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 illuminated by 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 is strictly located on the focal plane of the infinity-corrected microscope objective 8.

[0039] In S2 , 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. 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 reference light on the sample surface, the camera detects the imaging point on the sample surface, ensuring that the camera is located at the focal plane of the infinitely corrected microscope objective;

[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 mirror 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, and interferes 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, so that the camera 17 detects the imaging point on the surface of the sample 9 to ensure that the camera 17 is located in the focal plane of the infinity-corrected microscope objective 8 in real time;

[0042] The illumination power generated by the spot of 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] The light carrying the surface information of the sample 9 interferes with the reference light and is transmitted by the second beam splitter prism 12, and then is focused by the first lens 18 and filtered by the third aperture 19, and then emitted by the second lens 20. The two-quadrant photodetector 21 is placed in the conjugate plane of the rear focal plane of the infinity-corrected microscope objective 8 to collect the interference signals of the reflected light, the particle scattered light, the scattered-reflected light and the reference light in the far field, so as to detect the signal generated by the interaction between the sample 9 and the high numerical aperture illumination spot;

[0045] S5: using a two-quadrant photoelectric detector to collect far-field intensity signals and inputting them into a weak signal amplification circuit to amplify the two far-field intensity signals, and calculating the phase difference of the two photoelectric signals through a computer control system;

[0046] 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;

[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 in 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 second 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, 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;

[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 scanning 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, and the three-dimensional piezoelectric scanning stage 10 is driven to scan the sample 9 in the XY direction, and 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 method of the sample 9 in the XY direction is one of serpentine scanning and raster scanning, the scanning spacing in the X direction is ≤ 1 / 40 of the focus spot diameter, and the Y 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 by using a peak location algorithm and a particle size estimation algorithm;

[0055] 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 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 the surface height change 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 is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent replacement and improvement made to the above embodiments without departing from the content of the technical solution of the present invention, based on the technical essence of the present invention, within the spirit and principles of the present invention, still fall within the protection scope of the technical solution of the present invention.

Claims

1. A phase-differential coherent Fourier scattering surface particle detection device, characterized in that: The phase-differential coherent Fourier scattering surface particle detection device comprises: A laser (1), a collimating lens (2), a first aperture (3), a polarization state modulation module (4), a first beam splitter prism (5), a plane reflector (6), a piezoelectric driver (7), an infinity-corrected microscope objective lens (8), a sample (9), a three-dimensional piezoelectric scanning stage (10), a two-dimensional coarse adjustment displacement stage (11), a second beam splitter prism (12), a tube lens (13), a wide-field illumination light source (14), a second aperture (15), a third beam splitter prism (16), a camera (17), a first lens (18), a third aperture (19), a second lens (20), a two-quadrant photodetector (21), a weak signal amplification circuit (22), a data acquisition module (23), and a computer control system (24).

2. A phase difference coherent Fourier scattering surface particle detection device according to claim 1, characterized in that: The two-quadrant photoelectric detector (21) is located in a conjugate plane of the rear focal plane of the infinity correction microscope objective lens (8).

3. The phase-differential coherent Fourier scattering surface particle detection device according to claim 1, characterized in that: The wide-field illumination source (14) and the camera (17) are located at the focal plane of the tube lens (13).

4. A phase difference coherent Fourier scattering surface particle detection method, applied to a phase difference coherent Fourier scattering surface particle detection device according to claims 1-3, characterized in that: include: Step 1: Turn on the wide-field illumination light source (14), and after being reflected by the second aperture (15) and the third beam splitter prism (16), the light is emitted from the tube lens (13). After being reflected by the second beam splitter prism (12) and transmitted by the first beam splitter prism (5), the emitted light enters the infinity correction microscope objective lens (8) for focusing, thereby realizing wide-field illumination of the sample (9). A camera (17) is set to image the sample (9) so that the sample (9) is located in the focal plane of the infinity correction microscope objective lens (8). According to the imaging result, the position of the sample (9) is adjusted 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 then 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 then 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); 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), and 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 the interference signals of the reflected light, the particle scattered light, and the scattered reflected light and the reference light in the far field, so as to detect 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 between 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 three-dimensional piezoelectric scanning stage (10) is driven by a computer control system (24) to scan the sample (9) in the XY direction, and the oscillation period and amplitude of the piezoelectric driver (7) are controlled to achieve continuous modulation of the reference light phase, and the phase difference measurement value of each scanning position is recorded at the same time, and a phase difference measurement value image of the complete scanning area is constructed by reading the scanning data line by line; 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.

5. The phase differential coherent Fourier scattering surface particle detection method according to claim 4, characterized in that: 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.

6. A phase differential coherent Fourier scattering surface particle detection method according to claim 4, characterized in that: 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 405nm and 633nm.

7. The phase differential coherent Fourier scattering surface particle detection method according to claim 4, characterized in that: In step 2, the polarization state generated by the polarization state modulation module (4) is one of linear polarization and radial polarization.

8. The phase differential coherent Fourier scattering surface particle detection method according to claim 4, 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 lens (8) is less than 1 mW.

9. The phase differential coherent Fourier scattering surface particle detection method according to claim 4, characterized in that: 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.

10. The phase differential coherent Fourier scattering surface particle detection method according to claim 4, characterized in that: In step 7, the scanning interval 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 method is one of serpentine scanning and grating scanning, and the modulation method of the reference light phase is sinusoidal modulation.

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