High-sensitivity positioning atomic force microscope detection device and method

Abstract

The invention discloses a high-sensitivity positioning atomic force microscope detection device and method. The high-sensitivity positioning atomic force microscope detection device comprises a dark field oblique incidence light source module, an open atomic force scanning module, a microscopic imaging system and a high-precision motion platform for placing a sample, the dark field oblique incidence light source module provides a multi-angle oblique incidence light source for a sample to form a dark field effect, so that scattered light of micro-nano defects on the surface of the sample is captured by a microscopic imaging system, and high-sensitivity positioning is realized; the atomic force scanning module comprises a radio frequency modulation laser, a probe assembly and a photoelectric detector; the laser output by the laser irradiates the probe assembly and then is reflected into the photoelectric detector; the sample is a transparent element, and the relationship among the incident angle of the dark field oblique incidence light source module, the refractive index of the sample and the numerical aperture NA of the microscopic imaging system is constrained, so that the imaging of the center and the edge of the sample meets the dark field condition. By utilizing the method, the micro-nano scale surface defect can be accurately positioned in the AFM detection process.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical element detection, and in particular relates to a high-sensitivity positioning micro-nano defect atomic force microscope detection device and method. Background Art

[0002] Extreme optical fields, such as inertial confinement fusion systems, high-end lithography machines, and space telescopes, increasingly rely on ultra-high-precision optical components. However, the introduction of surface defects (such as micro- and nano-scale scratches and pitting) is unavoidable during ultra-precision machining. In extreme environments, such as high-energy lasers, these defects induce localized optical field modulation, potentially causing damage points, lowering the laser damage threshold and significantly limiting overall system optical performance and service life. Clarifying the three-dimensional morphology of surface defects facilitates theoretical research on defect-induced optical field modulation.

[0003] Currently, methods for detecting the 3D topography of surface defects include optical methods such as confocal microscopy, white-light interferometry, and structured light 3D reconstruction, as well as non-optical methods such as atomic force microscopy (AFM) and profilometry. Limited by the optical diffraction limit, optical methods struggle to achieve high-precision 3D reconstruction of micro- and nanoscale defects. AFM, on the other hand, can achieve nanometer or even sub-nanometer accuracy in both lateral and longitudinal directions, enabling high-precision 3D imaging of defects.

[0004] AFM inspection equipment typically requires additional auxiliary modules to locate the defect under test. After determining the target location, the probe or sample is moved for three-dimensional inspection. Currently, commonly used positioning auxiliary modules are basically brightfield illumination microscopes, such as the Chinese patent document CN118311300A that discloses an atomic force microscope; the Chinese patent document CN1259558C that discloses a modular atomic force microscope; and the Dimension Icon atomic force microscope produced by Bruker.

[0005] However, if a bright-field microscope is to locate surface defects at the micro- and nano-scale, the magnification of the imaging module needs to be increased, which means reducing the working distance of the positioning microscope and poses a challenge to the design of the AFM system. Summary of the Invention

[0006] The present invention provides a highly sensitive positioning atomic force microscope detection device and method, which can solve the problem that micro-nano defects cannot be located and thus it is difficult to determine the scanning area to be tested.

[0007] A high-sensitivity positioning atomic force microscope detection device, including a dark field oblique incident light source module, an open atomic force scanning module, a microscopic imaging system and a high-precision motion platform for placing samples; The dark field oblique incident light source module is used to provide the sample with multi-angle oblique incident light sources, forming a dark field effect, so that the scattered light of micro-nano defects on the sample surface can be captured by the microscopic imaging system, achieving high-sensitivity positioning; The atomic force scanning module includes a radio frequency modulated laser, a probe assembly and a photodetector; the laser output from the radio frequency modulated laser is irradiated on the probe assembly and then reflected into the photodetector; The sample is a transparent element, and the incident angle of the sample is illuminated by the dark field oblique incident light source module. , the refractive index of the sample , numerical aperture of the microscope imaging system NA The relationship between is constrained so that the imaging of the center and edge of the sample meets the dark field condition; The high-precision motion platform is used to cooperate with the dark-field oblique-incident light source module to locate surface defects on the sample, and to cooperate with the atomic force scanning module to perform three-dimensional imaging of the located defects.

[0008] The dark field oblique incident light source module adopts Kohler illumination and includes an LED, a collimating lens group and a projection lens group; After the LED output light passes through the collimating lens group and the projection lens group in sequence, the light is evenly and obliquely irradiated onto the sample surface, providing a dark-field light source for the microscopic imaging system. This converts the imaging mode of the microscopic imaging system into a dark-field mode for highly sensitive detection of micro-nano defects, thus achieving highly sensitive positioning. A dark-field oblique-incident light source module is arranged above the open atomic force scanning module to provide multiple oblique-incident light sources, enabling the dark-field light source to provide multi-angle illumination, thereby reducing the missed detection of directional defects.

[0009] The RF modulated laser broadens the spectrum width of the laser and reduces the temporal coherence length by setting the frequency of the RF modulated signal. The frequency selection method of the RF modulated signal is as follows: Superimpose bias current on RF modulated signal , and the injected current is obtained ;in, , is the frequency of the RF modulation signal, is the amplitude of the RF modulation signal; The modulation of the current causes the gain coefficient and the refractive index of the gain medium, which in turn causes amplitude modulation AM and phase modulation PM. The expression of the modulated light field is: ; Among them, the modulation depth , is the laser power generated by the bias current, is the laser power amplitude of RF modulation; modulation index , is the amplitude of the angular frequency modulation; using the Jacobi-Anger identity and Fourier series expansion, we can get: ; Among them, the coefficient , , yes Bessel function of the first kind, The intensity of the order sideband is: ; in, For the The complex amplitude of the order sideband; Radio frequency modulation creates sidebands in the laser spectrum, broadening the spectrum width; By modulating the laser parameters with RF, the different sideband intensities are calculated, and then the coherence length is calculated. ,in is the calibration fitting function, is the effective spectrum width; set the minimum value between the distance between the cantilever beam on the probe assembly and the sample surface and the sample thickness to ,when When , no interference occurs and the noise signal is suppressed.

[0010] Because the laser irradiates the cantilever beam while also irradiating the upper and lower surfaces of the sample, the scattered signal generated by the surface will interfere with the cantilever beam's reflected signal, affecting the detection results. By reducing the coherence length of the laser, the optical feedback noise and interference signals can be limited.

[0011] Preferably, a filter is installed in front of the photodetector to filter out the dark field illumination light and only receive the radio frequency laser.

[0012] Preferably, the atomic force scanning module further includes a first reflector and a second reflector. The laser light output by the RF-modulated laser sequentially passes through the first reflector, the probe assembly, and the second reflector before being reflected to the photodetector. By deflecting the light path through the reflectors, bulky components such as the RF-modulated laser and the photodetector are moved away from the measurement area, leaving as much open space above the sample as possible and reducing obstructions when the dark-field light source is incident at an angle, thereby forming an open atomic force scanning module.

[0013] Preferably, the high-precision motion platform comprises an XY large-range translation stage, an XY plane rotation stage and an XYZ three-axis small-range translation stage arranged in sequence from bottom to top; Among them, the XY large-range translation stage is used to perform full-aperture dark field high-sensitivity defect positioning on the sample, determine the position of the defect to be tested on the sample, and move the defect into the lateral scanning range of the probe assembly; The Z axis of the XYZ three-axis small-range translation stage is used to move the defect to be measured to the longitudinal measurement range of the probe assembly, and the XY axis is used to move the sample to enable the probe assembly to scan the defect; The XY rotation stage is used to rotate the sample to the position for imaging directional defects. Under darkfield oblique-incident illumination, the imaging of directional structures such as scratches is affected by the illumination azimuth. Due to obstruction by components such as the probe assembly, reflectors, and mechanical parts, the darkfield oblique-incident light source module cannot provide 360° azimuth illumination. By rotating the sample, 360° azimuth illumination of directional defects on the sample is achieved, eliminating missed detections due to directional variations.

[0014] Furthermore, when the XY plane rotating stage rotates the sample, the XY coordinates of the rotation center are set to , the coordinates of the current defect to be tested are , the sample rotates counterclockwise by an angle of θ When the coordinates after rotation Calculated by the following formula: ; Distance compensation through XY large-range translation stage and , obtain the illumination results of the defects to be measured on the sample surface at different defect angles within the same field of view of the microscopic imaging system, and avoid missed detection.

[0015] Furthermore, when the sample is a transparent component, scattered light from the high-precision motion platform on which the sample is placed can enter the microscopic imaging system, disrupting dark-field imaging conditions. To increase the versatility of the equipment and cover transparent component inspection, an ultra-smooth, high-reflectivity surface or blackbody material is placed as an intermediate layer between the XYZ three-axis short-range translation stage and the sample to prevent scattered light from the translation stage surface from disrupting dark-field conditions.

[0016] Furthermore, the incident angle of the dark field oblique incident light source module incident on the sample is , the refractive index of the sample , numerical aperture of the microscope imaging system The relationship is constrained as follows: ; ; Where, is the angle of incidence The corresponding refraction angle; the refracted light hits the back of the sample and the surface of the middle layer and is reflected. The incident angle of the reflected light hitting the side wall of the sample is , the corresponding refraction angle is ; Need to meet or ;like , then the imaging near the edge of the sample still meets the dark field condition; if , then total reflection occurs at the edge of the sample and emerges from the upper surface of the sample at an angle of , and still meet the dark field conditions.

[0017] A high-sensitivity positioning atomic force microscope detection method, using the above-mentioned atomic force microscope detection device, includes the following steps: S1, fix the sample to be tested on a high-precision motion platform in a horizontal position; place an ultra-smooth high-reflective surface or blackbody material between the sample and the high-precision motion platform; S2: Use the XY large-range translation stage in the high-precision motion platform to perform high-sensitivity positioning of full-aperture micro-nano defects on the sample, and move the defect to be measured on the sample into the lateral scanning range of the probe assembly. If the defect is directional, operate the XY large-range translation stage and XY plane rotation stage in the high-precision motion platform to rotate and translate the defect to the optimal imaging position. S3, operate the XYZ three-axis small-range translation stage in the high-precision motion platform to move the defect to be tested on the sample into the measurement range of the probe assembly; S4, use the atomic force scanning module to measure and obtain the three-dimensional morphology of the defect to be tested.

[0018] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention provides a multi-angle oblique incident light source for the sample by setting a dark field oblique incident light source module, and designs an open atomic force scanning module, combining the high-sensitivity positioning of dark field and the high-precision detection capability of AFM to achieve cross-scale nanoscale microstructure positioning and three-dimensional morphology imaging.

[0019] 2. The present invention designs a radio frequency modulated laser and selects a suitable radio frequency signal frequency based on theoretical derivation and the probe working distance.

[0020] 3. The present invention takes into account the occlusion of components and combines the translation stage and the rotation stage to achieve all-round defect detection without missing any defects.

[0021] 4. The present invention expands the detection capability of transparent components, analyzes and derives the influence of edge scattering, and expands the dark field detection area. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the overall structure of an atomic force microscope detection device with high sensitivity positioning according to the present invention.

[0023] Figure 2 It is a schematic diagram of the structure of the present invention when viewed from above.

[0024] Figure 3 Schematic diagram of the high-precision motion platform in the present invention.

[0025] Figure 4 Schematic diagram of the rotation positioning coordinates in the present invention.

[0026] Figure 5 Schematic diagram of edge detection of a transparent element according to the present invention.

[0027] Figure 6 This is a test result diagram of the present invention. DETAILED DESCRIPTION

[0028] The present invention will be described in further detail below with reference to the accompanying drawings and examples. It should be noted that the following examples are intended to facilitate understanding of the present invention and do not have any limiting effect on the present invention.

[0029] like Figure 1 and Figure 2 As shown, a high-sensitivity positioning atomic force microscope detection device includes an open atomic force scanning module, a dark field oblique incident light source module 5, a microscopic imaging system 7 and a high-precision motion platform 9 for placing a sample 8.

[0030] The atomic force scanning module includes a radio frequency modulated laser 1, a first reflector 21, a probe assembly 6, a second reflector 22, and a photodetector 3. The laser output from the radio frequency modulated laser 1 passes through the first reflector 21, the probe assembly 6, and the second reflector 22 in sequence and is then reflected into the photodetector 3.

[0031] A filter is installed in front of the photodetector 3 to eliminate the influence of oblique incident light in the dark field. The RF modulated laser 1 widens the spectrum width of the laser and reduces the temporal coherence length by setting the frequency of the RF modulation signal.

[0032] Because the laser irradiates the cantilever beam of the probe assembly 6 while also irradiating the upper and lower surfaces of the sample, the scattered signal generated by the surface interferes with the reflected signal from the cantilever beam, affecting the detection results. By reducing the coherence length of the laser, the optical feedback noise and interference signals can be limited.

[0033] The frequency selection method of the RF modulation signal is as follows: Superimpose bias current on RF modulated signal , and the injected current is obtained ;in, , is the frequency of the RF modulation signal, is the amplitude of the RF modulation signal; The modulation of the current causes the gain coefficient and the refractive index of the gain medium, which in turn causes amplitude modulation AM and phase modulation PM. The expression of the modulated light field is: ; Among them, the modulation depth , is the laser power generated by the bias current, is the laser power amplitude of RF modulation; modulation index , is the amplitude of the angular frequency modulation; using the Jacobi-Anger identity and Fourier series expansion, we can get: ; Among them, the coefficient , , yes Bessel function of the first kind, The intensity of the order sideband is: ; in, For the The complex amplitude of the order sideband; Radio frequency modulation creates sidebands in the laser spectrum, broadening the spectrum width; By modulating the laser parameters with RF, the different sideband intensities are calculated, and then the coherence length is calculated. ,in is the calibration fitting function, is the effective spectrum width; set the minimum value between the distance between the cantilever beam on the probe assembly and the sample surface and the sample thickness to ,when When , no interference occurs and the noise signal is suppressed.

[0034] When the probe assembly 6 is scanning, the probe interacts with the surface of the sample 8, causing the cantilever to deflect, thereby changing the laser reflected on the photodetector 3. The light path is refracted by the first reflector 21 and the second reflector 22, and large-volume devices such as the RF modulated laser 1 and the photodetector 3 are moved away from the measurement area, so that the area above the sample 8 is as open as possible, reducing obstructions when the dark field oblique incident light source module 5 is obliquely incident. The precision manual adjustment frame 41 and the precision manual adjustment frame 12 can adjust the position of the RF modulated laser 1, and the precision manual adjustment frame 42 and the precision manual adjustment frame 14 can adjust the position of the photodetector 3, so as to accurately obtain the feedback signal of the cantilever beam. The precision manual adjustment frame 10 can be used to test samples 8 of different thicknesses.

[0035] The microscopic imaging system 7 comprises an imaging lens assembly and an imaging CCD / CMOS component. The dark-field oblique-incidence light source module 5, comprising an LED, a collimator, and a projection module, collimates the LED light before projecting it, evenly irradiating the surface of the sample 8. With a narrow divergence angle, reflected light does not enter the microscopic imaging system 7, capturing only scattered light from defects and improving defect detection sensitivity. Specially customized miniaturization of the optical lens assembly reduces interference with the atomic force scanner module and provides illumination in a wide range of directions.

[0036] like Figure 3 As shown, the high-precision motion platform 9 consists of an XYZ three-axis small-range translation stage 91, an XY large-range translation stage 93, and an XY plane rotation stage 92. The XYZ three-axis small-range translation stage 91 is used for ultra-high-precision AFM detection, and the probe assembly 6 scans the defect by moving the sample 8; wherein, the Z axis is used to adjust the sample to move the defect to be measured to the longitudinal measurement range of the probe assembly 6. The XY large-range translation stage 93 cooperates with the dark field to scan the sample 8 at full aperture to locate the defect to be measured, and then moves it under the probe assembly 6. The entire system is placed on the vibration isolation platform 11 to ensure the detection accuracy of the AFM.

[0037] Under dark field oblique incident illumination, the imaging results of directional structures such as scratches will be affected by the illumination azimuth angle. Figure 2 As shown, due to the obstruction of the probe assembly 6, the reflector 2, the mechanical parts and other components, the dark field oblique incident light source module 5 cannot provide 360° azimuth lighting coverage, and needs to cooperate with the XY plane rotation stage 92 to achieve full angle coverage.

[0038] like Figure 4 As shown, set the XY coordinates of the rotation center to , the coordinates of the current defect to be tested are , the sample rotates counterclockwise by an angle of θ , after rotation the coordinates are It can be calculated by the following formula: ; Compensate distance by XY large range translation stage 93 and It can realize the lighting results of defects to be tested at different angles in the same field of view, eliminating missed detection.

[0039] When the measurement object is a transparent component, the scattered light generated by the sample stage that fixes the sample will enter the microscopic imaging system, thereby destroying the dark field condition. In order to increase the versatility of the equipment and cover the detection of transparent components, it is necessary to place an intermediate layer 13 of ultra-smooth high-reflective surface or black body material between the sample 8 and the XYZ three-axis small-range translation stage 91. Figure 5As shown, the influence of the sample edge needs to be taken into account. In order to reduce the influence of the sample edge and expand the dark field detection range, the incident angle of the dark field oblique incident light source module needs to be adjusted. , Material of the sample to be tested , numerical aperture of high-magnification microscopy systems Constrain the relationship: According to the law of refraction, the angle of incidence and the angle of refraction The relationship is ; The refracted light hits the high reflective surface and is reflected. If the reflected light hits the side wall of the sample, the angle is , refracted light (angle is ) may enter the high-magnification microscopy system and destroy the dark field conditions: ; Satisfy the above two formulas: ; Need to meet or ;like Then the imaging near the edge of the sample still meets the dark field condition, the imaging result has high contrast, and the detection range on transparent samples is expanded. , then total reflection occurs at the edge of the sample and emerges from the upper surface of the sample at an angle of , and still meet the dark field conditions.

[0040] like Figure 6 To demonstrate the improved detection sensitivity, a coaxial illumination light source was installed on the microscopic imaging system 7, allowing comparison of brightfield and darkfield imaging results within the same field of view. The upper left image shows a brightfield microscopic image of the device, showing no defects; the upper right image shows a darkfield microscopic image of the device, showing defects; the lower left image shows the AFM measurement results of the device, and the lower right image corresponds to the cross-sectional distribution of the AFM measurement results, showing a defect of approximately 0.7 μm in width and 2 nm in depth. This demonstrates that the present invention possesses both high-sensitivity darkfield nanometer-scale positioning and high-precision AFM detection capabilities.

[0041] The embodiments described above provide a detailed description of the technical solutions and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements and equivalent substitutions made within the scope of the principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A highly sensitive positioning atomic force microscope detection device, characterized in that: It includes a dark field oblique incident light source module (5), an open atomic force scanning module, a microscopic imaging system (7), and a high-precision motion platform (9) for placing a sample (8); The dark field oblique incident light source module (5) is used to provide a multi-angle oblique incident light source for the sample (8), forming a dark field effect, so that the scattered light of micro-nano defects on the surface of the sample (8) is captured by the microscopic imaging system (7), thereby achieving high-sensitivity positioning; The atomic force scanning module comprises a radio frequency modulated laser (1), a probe assembly (6), and a photoelectric detector (3); the radio frequency modulated laser (1) outputs laser light which is irradiated on the probe assembly (6) and then reflected into the photoelectric detector (3); The sample (8) is a transparent element, and the incident angle of the dark field oblique incident light source module (5) is used to illuminate the sample (8). , the refractive index of the sample , numerical aperture of the microscopic imaging system (7) NA The relationship is constrained so that the imaging of the center and edge of the sample (8) meets the dark field condition; The high-precision motion platform (9) is used to cooperate with the dark-field oblique-incident light source module (5) to locate surface defects on the sample (8), and to cooperate with the atomic force scanning module to perform three-dimensional imaging of the located defects.

2. The high-sensitivity positioning atomic force microscope detection device according to claim 1, characterized in that: The dark field oblique incident light source module (5) adopts Kohler illumination and comprises an LED, a collimating lens group and a projection lens group; After the LED output light passes through the collimating lens group and the projection lens group in sequence, the light is evenly and obliquely irradiated onto the surface of the sample (8), providing a dark field light source for the microscopic imaging system (7), so that the imaging mode of the microscopic imaging system (7) is converted into a dark field mode for high-sensitivity detection of micro-nano defects, thereby achieving high-sensitivity positioning; a dark field oblique incident light source module (5) is arranged above the open atomic force scanning module to provide multiple oblique incident light sources, so that the dark field light source provides multi-angle illumination, thereby reducing the missed detection of directional defects.

3. The high-sensitivity positioning atomic force microscope detection device according to claim 1, characterized in that: The radio frequency modulated laser (1) widens the spectrum width of the laser and reduces the temporal coherence length by setting the frequency of the radio frequency modulated signal; the frequency selection method of the radio frequency modulated signal is as follows: Superimpose bias current on RF modulated signal , and the injected current is obtained ;in, , is the frequency of the RF modulation signal, is the amplitude of the RF modulation signal; The modulation of the current causes the gain coefficient and the refractive index of the gain medium, which in turn causes amplitude modulation AM and phase modulation PM. The expression of the modulated light field is: ； Among them, the modulation depth , is the laser power generated by the bias current, is the laser power amplitude of RF modulation; modulation index , is the amplitude of the angular frequency modulation; using the Jacobi-Anger identity and Fourier series expansion, we can get: ； Among them, the coefficient , , yes Bessel function of the first kind, The intensity of the order sideband is: ； in, For the The complex amplitude of the order sideband; Radio frequency modulation creates sidebands in the laser spectrum, broadening the spectrum width; By modulating the laser parameters with RF, the different sideband intensities are calculated, and then the coherence length is calculated. ,in is the calibration fitting function, is the effective spectrum width; set the minimum value between the distance between the cantilever beam on the probe assembly and the sample surface and the sample thickness to ,when When , no interference occurs and the noise signal is suppressed.

4. The high-sensitivity positioning atomic force microscope detection device according to claim 1, characterized in that: A filter is installed in front of the photodetector (3) for filtering out dark field illumination light and receiving only radio frequency laser light.

5. The high-sensitivity positioning atomic force microscope detection device according to claim 1, characterized in that: The atomic force scanning module further comprises a first reflector and a second reflector, and the laser output by the radio frequency modulated laser (1) passes through the first reflector, the probe assembly (6) and the second reflector in sequence and is reflected into the photoelectric detector (3).

6. The high-sensitivity positioning atomic force microscope detection device according to claim 1, characterized in that: The high-precision motion platform (9) comprises an XY large-range displacement stage (93), an XY plane rotation stage (92), and an XYZ three-axis small-range displacement stage (91) arranged in sequence from bottom to top; The XY large-range translation stage (93) is used to perform full-aperture dark-field high-sensitivity defect positioning on the sample (8), determine the position of the defect to be measured on the sample (8), and move the defect into the lateral scanning range of the probe assembly (6); The Z axis of the XYZ three-axis small-range translation stage (91) is used to move the defect to be measured to the longitudinal measurement range of the probe assembly (6), and the XY axis is used to move the sample (8) to enable the probe assembly (6) to scan the defect; The XY plane rotating stage (92) is used to rotate the sample (8) to a position where the directional defects on the sample (8) are imaged; by rotating the sample, 360° azimuth illumination of the directional defects on the sample (8) is compensated, thereby eliminating missed detection due to directionality.

7. The high-sensitivity positioning atomic force microscope detection device according to claim 6, characterized in that: When the XY plane rotating stage (92) rotates the sample (8), the XY coordinates of the rotation center are set to , the coordinates of the current defect to be tested are , the sample (8) rotates counterclockwise by an angle of θ When the coordinates after rotation Calculated by the following formula: ； Distance compensation by XY large range translation stage (93) and , and obtain the illumination results of the defect to be measured on the surface of the sample (8) in the same field of view of the microscopic imaging system (7) at different defect angles.

8. The high-sensitivity positioning atomic force microscope detection device according to claim 6, characterized in that: An ultra-smooth high-reflective surface or blackbody material is placed between the XYZ three-axis small-range translation stage (91) and the sample (8) as an intermediate layer to prevent scattered light on the surface of the translation stage from destroying the dark field condition.

9. The high-sensitivity positioning atomic force microscope detection device according to claim 1, characterized in that: The incident angle of the dark field oblique incident light source module (5) incident on the sample (8) , the refractive index of the sample , numerical aperture of the microscopic imaging system (7) The relationship is constrained as follows: ； ； Where, is the angle of incidence The corresponding refraction angle; the refracted light hits the back of the sample and the surface of the middle layer and is reflected. The incident angle of the reflected light hitting the side wall of the sample is , the corresponding refraction angle is ; Need to meet or ;like , then the imaging near the edge of the sample still meets the dark field condition; if , then total reflection occurs at the edge of the sample and emerges from the upper surface of the sample at an angle of , and still meet the dark field conditions.

10. A high-sensitivity positioning atomic force microscope detection method, characterized in that: Using the atomic force microscope detection device according to any one of claims 1 to 9, The following steps are involved: S1, fix the sample to be tested on a high-precision motion platform in a horizontal position; place an ultra-smooth high-reflective surface or blackbody material between the sample and the high-precision motion platform; S2, using the XY large-range translation stage in the high-precision motion platform to perform high-sensitivity positioning of full-aperture micro-nano defects on the sample, moving the defect to be tested on the sample into the lateral scanning range of the probe assembly; If the defect has directionality, operate the XY large-range translation stage and XY plane rotation stage in the high-precision motion platform to rotate and translate the defect to the optimal imaging position; S3, operate the XYZ three-axis small-range translation stage in the high-precision motion platform to move the defect to be tested on the sample into the measurement range of the probe assembly; S4, use the atomic force scanning module to measure and obtain the three-dimensional morphology of the defect to be tested.

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