Three-dimensional scanning measuring head of metering type atomic force microscope

Abstract

The invention discloses a three-dimensional scanning probe of a metering type atomic force microscope, and relates to the technical field of atomic force microscopes, and the three-dimensional scanning probe of the metering type atomic force microscope comprises a load module, a three-dimensional orthogonal scanning module and a laser interference measurement module. A probe, a probe stress detection unit and a reflector group are fixed in the load module, the load module is fixed on a movable part of the three-dimensional orthogonal scanning module, and the three-dimensional orthogonal scanning module drives the probe to perform scanning in X and Y directions and sample morphology feedback in a Z direction relative to a sample on the sample table; and meanwhile, laser is emitted to a reflector group on the load module, and a measurement result of the laser interference measurement module is obtained, so that the actual three-dimensional displacement of the tip of the probe relative to the surface of the sample is calculated. Abbe errors caused by the fact that the measuring shaft does not pass through the tip of the probe are compensated through a laser interference measurement result, and measurement of surface microstructure parameters of a large sample can be achieved in cooperation with a large-size sample table.

Description

Technical Field

[0001] The present application relates to the technical field of atomic force microscopes, and in particular to a three-dimensional scanning probe of a metrological atomic force microscope. Background Art

[0002] Atomic force microscope (AFM) is a precision measuring instrument with sub-nanometer three-dimensional resolution. It can realize non-destructive characterization of microscopic three-dimensional morphology and physical properties of various solid materials and even biological tissue surfaces, and has a wide range of applications in scientific research and advanced industrial fields. The basic working principle of common AFM equipment is to use a micro cantilever probe to touch the sample with a certain force and use a piezoelectric ceramic scanner to make the two perform relative scanning motion in the XY plane. During the scanning process, the real-time Z-direction feedback of the scanner is used to maintain the force between the probe and the sample unchanged, that is, to keep the distance between the needle tip and the sample constant. The motion trajectory of the needle tip relative to the sample reflects the three-dimensional morphology of the sample surface.

[0003] Although AFM can give the surface three-dimensional dimensions of micro-nano structures with high resolution, the measurement data of most AFM equipment do not have metrological effect. There are two reasons for this: First, the size measurement value of AFM should be the relative displacement between the needle tip and the sample, but ordinary AFM does not directly measure this displacement, but measures the displacement of the scanner. The displacement of each axis of the scanner is generally measured by the internally integrated displacement sensor. The measurement axis (extension line) of these sensors does not pass through the point where the needle tip is located, and does not meet the Abbe principle, that is, the change in the attitude angle when the scanner is displaced will cause the value measured by the displacement sensor to be not equal to the actual relative displacement between the needle tip and the sample. Second, the displacement sensor integrated in the ordinary AFM scanner is generally a capacitive sensor, an inductive sensor or a strain gauge sensor, and its displacement measurement value (sample size measurement result) cannot be directly related to the definition of the length unit, that is, the laser wavelength, and must be calibrated by a higher-level device or standard.

[0004] The lack of metrological properties makes it difficult to compare the measurement results of different AFM devices or the measurement results of AFM and other devices, which is not conducive to the evaluation and control of process consistency in industrial production. In response to this, relevant institutions have developed metrological AFM. These metrological AFMs generally adopt a downward scanning instrument architecture, that is, the probe does not move, and the scanner drives the sample to move in three dimensions. Three mutually orthogonal mirrors are installed on the two adjacent sides and bottom of the sample stage. The lasers emitted by the X, Y, and Z interferometers are respectively vertically hit on the three mirrors, and the extended lines of the beams intersect at the tip of the needle.

[0005] However, the above-mentioned metrological AFM with downward scanning structure has an obvious disadvantage, that is, the size and weight of the sample are limited by the carrying capacity of the scanner, which means that this type of instrument can only be used for the detection of small samples. For large industrial samples, there is currently no suitable metrological AFM equipment. Summary of the invention

[0006] The purpose of this application is to provide a three-dimensional scanning probe for a metrological atomic force microscope, which compensates for the Abbe error caused by the displacement measurement axis not passing through the needle tip through a laser interferometry measurement module, and can achieve measurement of microscopic morphology parameters of the surface of large samples in conjunction with a large-size sample stage.

[0007] To achieve the above objectives, this application provides the following solutions:

[0008] The present application provides a three-dimensional scanning probe for a metrological atomic force microscope, comprising: a load module, a three-dimensional orthogonal scanning module and a laser interferometer measurement module; the load module is used to fix a probe, a probe force detection unit and a reflector group, and the load module is fixed on the movable part of the three-dimensional orthogonal scanning module; the three-dimensional orthogonal scanning module is used to drive the probe to perform scanning in the X and Y directions and sample morphology feedback in the Z direction relative to the sample on the sample stage; the laser interferometer measurement module is used to emit laser to the reflector group arranged on the load module and obtain laser interferometer measurement results, so as to solve the actual three-dimensional displacement of the probe tip relative to the sample surface according to the measurement results of the laser interferometer measurement module.

[0009] Optionally, the load module includes: a probe, a probe holder, a probe force detection unit, a reflector group and a rigid frame; the reflector group includes an X-axis reflector, a Y-axis reflector and a Z-axis reflector.

[0010] The probe is fixed on the probe holder, and the tip of the probe is located at the lowest point of the three-dimensional scanning probe; the probe holder and the probe force detection unit are both fixed on the rigid frame, and the rigid frame is fixed on the movable part of the three-dimensional orthogonal scanning module; the X-axis reflector and the Y-axis reflector are respectively fixed on two adjacent orthogonal surfaces of the rigid frame, and the reflection surfaces of the X-axis reflector and the Y-axis reflector face outward and are respectively perpendicular to the X-axis and the Y-axis; the Z reflector is fixed on the bottom of the probe holder, and the reflection surface of the Z reflector faces upward and is perpendicular to the Z axis.

[0011] Optionally, the probe force detection unit adopts an optical lever optical path or a self-sensing circuit according to the type of the probe.

[0012] Optionally, the three-dimensional orthogonal scanning module comprises: a fixed part and a movable part; the movable part drives the probe of the load module to perform scanning in the X and Y directions and feedback movement in the Z direction relative to the sample on the sample stage.

[0013] Optionally, the laser interferometry measurement module includes: a first mounting frame, a second mounting frame, a right-angle reflector, a first laser interferometry probe, a second laser interferometry probe, a third laser interferometry probe, a fourth laser interferometry probe, a fifth laser interferometry probe and a sixth laser interferometry probe; the first mounting frame and the second mounting frame are fixedly mounted on the fixed part of the three-dimensional orthogonal scanning module; the first laser interferometry probe, the second laser interferometry probe, the third laser interferometry probe, the fourth laser interferometry probe, the fifth laser interferometry probe and the sixth laser interferometry probe are fixedly mounted on the first mounting frame; the right-angle reflector is fixedly mounted on the second mounting frame, and the right-angle reflector is used to reflect the laser of the sixth laser interferometry probe to the Z-axis reflector.

[0014] The first laser interferometer probe, the second laser interferometer probe and the third laser interferometer probe are respectively facing the X-axis reflector, and the first laser interferometer probe, the second laser interferometer probe and the third laser interferometer probe respectively emit lasers to the X-axis reflector and receive reflected light to accurately measure the X-axis displacement of the probe; the three laser points of the first laser interferometer probe, the second laser interferometer probe and the third laser interferometer probe on the X-axis reflector are not collinear.

[0015] The fourth laser interferometer probe and the fifth laser interferometer probe are respectively facing the Y-axis reflector, and the fourth laser interferometer probe and the fifth laser interferometer probe respectively emit lasers to the Y-axis reflector and receive reflected light to accurately measure the Y-axis displacement of the probe.

[0016] The sixth laser interferometer probe faces the right-angle reflector, emits laser light to the right-angle reflector, reflects the laser light to the Z-axis reflector through the right-angle reflector, and receives reflected light to accurately measure the Z-axis displacement of the probe.

[0017] Optionally, calculating the actual three-dimensional displacement of the probe tip relative to the sample surface according to the measurement result of the laser interferometer measurement module specifically includes the following steps:

[0018] After the needle tip contacts the sample surface, the intersection of the planes where the X-axis reflector, the Y-axis reflector and the Z-axis reflector are located is taken as the origin O, and the planes where the three reflectors are located are X=0, Y=0, and Z=0 respectively, to establish the initial coordinate system of the load module, which is regarded as a fixed world coordinate system.

[0019] When the three-dimensional orthogonal scanning module drives the probe to scan, the current coordinate system of the load module is determined according to the change of the measurement result of the laser interferometer measurement module, and the current coordinate system of the load module reflects the position and posture of the load module in the world coordinate system at the current moment.

[0020] According to the load module initial coordinate system and the load module current coordinate system, a rotation matrix and a translation vector from the load module initial coordinate system to the load module current coordinate system are determined.

[0021] According to the coordinates of the probe tip in the initial coordinate system of the load module, the rotation matrix and translation vector from the initial coordinate system of the load module to the current coordinate system of the load module, the actual three-dimensional displacement of the probe tip relative to the fixed sample from the initial moment to the current moment is calculated.

[0022] Optionally, determining the current coordinate system of the load module according to the change of the measurement result of the laser interferometer measurement module specifically includes the following steps:

[0023] According to the change of the measurement result of the laser interferometer measurement module, the equation of the plane where the X-axis reflector is currently located in the world coordinate system and the X-axis vector of the current coordinate system of the load module are determined.

[0024] According to the change of the measurement result of the laser interferometer measurement module and the X-axis vector of the current coordinate system of the load module, the equation of the plane where the Y-axis reflector is currently located in the world coordinate system and the Y-axis vector of the current coordinate system of the load module are determined.

[0025] According to the change of the measurement result of the laser interferometer measurement module, the X-axis vector of the current coordinate system of the load module and the Y-axis vector of the current coordinate system of the load module, the equation of the plane where the Z-axis reflector is currently located in the world coordinate system and the Z-axis vector of the current coordinate system of the load module are determined.

[0026] The coordinates of the origin of the current coordinate system of the load module in the world coordinate system are obtained according to the equation of the plane where the X-axis reflector is currently located, the equation of the plane where the Y-axis reflector is currently located, and the equation of the plane where the Z-axis reflector is currently located.

[0027] The current coordinate system of the load module is determined according to the X-axis vector of the current coordinate system of the load module, the Y-axis vector of the current coordinate system of the load module, the Z-axis vector of the current coordinate system of the load module and the origin of the current coordinate system of the load module.

[0028] Optionally, the measurement results of the laser interferometry measurement module include: the measurement results of the first laser interferometry probe, the measurement results of the second laser interferometry probe, the measurement results of the third laser interferometry probe, the measurement results of the fourth laser interferometry probe, the measurement results of the fifth laser interferometry probe and the measurement results of the sixth laser interferometry probe.

[0029] Optionally, the X-axis vector of the current coordinate system of the load module is determined according to the following formula:

[0030]

[0031] Among them, (k1, m1, n1) is the X-axis vector of the current coordinate system of the load module, K1, M1 and N1 are the plane equation coefficients of the plane where the X-axis reflector is currently located; the plane equation coefficients of the plane where the X-axis reflector is currently located are determined according to the following formula:

[0032]

[0033] Among them, (x a' ,y a ,z a ) is the world coordinate of the laser reflection point of the first laser interferometer probe on the X-axis reflector at the current moment, (x b' ,y b ,z b ) is the world coordinate of the laser reflection point of the second laser interferometer probe on the X-axis reflector at the current moment, (x c' ,y c ,z c ) is the world coordinate of the laser reflection point of the third laser interferometer probe on the X-axis reflector at the current moment.

[0034] Determine the Y-axis vector of the current coordinate system of the load module according to the following formula:

[0035]

[0036] Among them, (k2, m2, n2) is the Y-axis vector of the current coordinate system of the load module, K2, M2 and N2 are the plane equation coefficients of the plane where the Y-axis reflector is currently located; the plane equation coefficients of the plane where the Y-axis reflector is currently located are determined according to the following formula:

[0037]

[0038] Among them, (x d' ,y d ,z d ) is the world coordinate of the laser reflection point of the fourth laser interferometer probe on the Y-axis reflector at the current moment, (x e' ,ye ,z e ) is the world coordinate of the laser reflection point of the fifth laser interferometer probe on the Y-axis reflector at the current moment.

[0039] Determine the Z-axis vector of the load module's current coordinate system according to the following formula:

[0040]

[0041] Among them, (k3, m3, n3) is the Z-axis vector of the current coordinate system of the load module, K3, M3 and N3 are the plane equation coefficients of the plane where the Z-axis reflector is currently located; the plane equation coefficients of the plane where the Z-axis reflector is currently located are determined according to the following formula:

[0042]

[0043] Among them, (x f' ,y f ,z f ) is the world coordinate of the laser reflection point of the sixth laser interferometer probe on the Z-axis reflector at the current moment.

[0044] Optionally, the rotation matrix from the initial coordinate system of the load module to the current coordinate system of the load module is expressed by the following formula:

[0045]

[0046] Among them, R is the rotation matrix from the initial coordinate system of the load module to the current coordinate system of the load module.

[0047] The translation vector from the initial coordinate system of the load module to the current coordinate system of the load module is expressed by the following formula:

[0048]

[0049] Wherein, D is the translation vector from the initial coordinate system of the load module to the current coordinate system of the load module.

[0050] The actual three-dimensional displacement of the probe tip relative to the stationary sample from the initial moment to the current moment is calculated according to the following formula:

[0051]

[0052] Where S is the actual three-dimensional displacement of the probe tip relative to the fixed sample from the initial moment to the current moment, (x P' ,y P' ,z P' ) is the world coordinate of the probe tip at the current moment, (x P ,y P ,z P) is the coordinate of the probe tip in the initial coordinate system of the load module at the initial moment, that is, the world coordinate of the probe tip at the initial moment.

[0053] According to the specific embodiments provided in this application, this application discloses the following technical effects:

[0054] The present application provides a three-dimensional scanning probe of a metrological atomic force microscope, including: a load module, a three-dimensional orthogonal scanning module and a laser interferometer measurement module. A probe, a probe force detection unit and a reflector group are fixed in the load module. The load module is fixed on the movable part of the three-dimensional orthogonal scanning module. The probe is driven by the three-dimensional orthogonal scanning module to perform scanning in the X and Y directions and sample morphology feedback in the Z direction relative to the sample on the sample stage; at the same time, the laser interferometer measurement module emits laser to the reflector group set on the load module and obtains the laser interferometer measurement result, so as to calculate the actual three-dimensional displacement of the probe tip relative to the sample surface according to the measurement result. The present application compensates the Abbe error caused by the displacement measurement axis not passing through the probe tip through the measurement result of the laser interferometer measurement module, and can realize the measurement of the microscopic morphological parameters of the surface of large samples in conjunction with the large-size sample stage, breaking the limitation of the sample size on the traditional metrological atomic force microscope, and can realize the accurate measurement of the microstructure of the surface of large samples; and because of the use of laser interferometer measurement, the size detection result of the atomic force microscope can be traced back to the laser wavelength, which has metrological significance. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0056] Figure 1 A schematic structural diagram of a three-dimensional scanning probe of a metrological atomic force microscope provided in one embodiment of the present application.

[0057] Figure 2 A flowchart of actual displacement calculation of a three-dimensional scanning probe of a metrological atomic force microscope provided in one embodiment of the present application.

[0058] Figure 3 A flowchart of step A2 in the actual displacement calculation process of a three-dimensional scanning probe of a metrological atomic force microscope provided in one embodiment of the present application. DETAILED DESCRIPTION

[0059] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0060] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0061] In an exemplary embodiment, Figure 1 As shown, a three-dimensional scanning probe of a metrological atomic force microscope is provided, comprising: a load module, a three-dimensional orthogonal scanning module and a laser interferometer measurement module; the load module is used to fix a probe, a probe force detection unit and a reflector group, and the load module is fixed on the movable part of the three-dimensional orthogonal scanning module; the three-dimensional orthogonal scanning module is used to drive the probe to perform scanning in the X and Y directions and sample morphology feedback in the Z direction relative to the sample on the sample stage; the laser interferometer measurement module is used to emit laser to the reflector group arranged on the load module and obtain laser interferometer measurement results, so as to solve the actual three-dimensional displacement of the probe tip relative to the sample surface according to the measurement results of the laser interferometer measurement module.

[0062] Specifically in this embodiment, the load module includes: a probe, a probe holder, a probe force detection unit, a reflector group and a rigid frame; the reflector group includes an X-axis reflector, a Y-axis reflector and a Z-axis reflector.

[0063] The probe is fixed on the probe holder, and the tip of the probe is located at the lowest point of the three-dimensional scanning probe; the probe holder and the probe force detection unit are both fixed on the rigid frame, and the rigid frame is fixed on the movable part of the three-dimensional orthogonal scanning module; the X-axis reflector and the Y-axis reflector are respectively fixed on two adjacent orthogonal surfaces of the rigid frame, and the reflection surface of the X-axis reflector and the reflection surface of the Y-axis reflector face outward and are respectively perpendicular to the X-axis and the Y-axis; the Z reflector is fixed on the bottom of the probe holder, and the reflection surface of the Z reflector faces upward and is perpendicular to the Z axis. Specifically, the probe force detection unit adopts an optical lever optical path or a self-sensing circuit according to the type of the probe.

[0064] Specifically in this embodiment, the three-dimensional orthogonal scanning module includes: a fixed part and a movable part; in this embodiment, the three-dimensional orthogonal scanning module is a nano displacement stage, which is divided into a fixed part and a movable part. The movable part drives the probe of the load module to perform scanning in the X and Y directions and feedback movement in the Z direction relative to the sample on the sample stage. A through hole is provided between the fixed part and the movable part, and the optical microscopic observation module can observe the probe and the sample through the through hole.

[0065] In another exemplary embodiment, the optical microscope observation module is an upright optical microscope installed directly above the through hole of the three-dimensional orthogonal scanning module; the function of the optical microscope observation module is to assist in observing the state and relative position of the probe and the sample.

[0066] Specifically in this embodiment, the laser interferometry measurement module includes: a first mounting frame, a second mounting frame, a right-angle reflector, a first laser interferometry probe, a second laser interferometry probe, a third laser interferometry probe, a fourth laser interferometry probe, a fifth laser interferometry probe and a sixth laser interferometry probe; the first mounting frame and the second mounting frame are fixedly mounted on the fixed part of the three-dimensional orthogonal scanning module; the first laser interferometry probe, the second laser interferometry probe, the third laser interferometry probe, the fourth laser interferometry probe, the fifth laser interferometry probe and the sixth laser interferometry probe are fixedly mounted on the first mounting frame; the right-angle reflector is fixedly mounted on the second mounting frame, and the right-angle reflector is used to reflect the laser of the sixth laser interferometry probe to the Z-axis reflector.

[0067] The first laser interferometer probe, the second laser interferometer probe and the third laser interferometer probe are respectively facing the X-axis reflector, and the first laser interferometer probe, the second laser interferometer probe and the third laser interferometer probe respectively emit lasers to the X-axis reflector and receive reflected light to accurately measure the X-axis displacement of the probe; the three laser reflection points of the first laser interferometer probe, the second laser interferometer probe and the third laser interferometer probe on the X-axis reflector are not collinear. Assume that the intersection points of the three laser beams emitted by the first laser interferometer probe, the second laser interferometer probe and the third laser interferometer probe and the X-axis reflector are a, b, and c, respectively, and a, b, and c are not collinear.

[0068] The fourth laser interferometer probe and the fifth laser interferometer probe are respectively oriented toward the Y-axis reflector, and the fourth laser interferometer probe and the fifth laser interferometer probe respectively emit lasers to the Y-axis reflector and receive reflected light to accurately measure the Y-axis displacement of the probe. Assume that the intersection points of the two beams of light emitted by the fourth laser interferometer probe and the fifth laser interferometer probe and the Y-axis reflector are d and e, and the line connecting d and e is not parallel to the X-axis.

[0069] The sixth laser interferometer probe faces the right-angle reflector, emits laser light to the right-angle reflector, reflects the laser light to the Z-axis reflector through the right-angle reflector, and receives the reflected light to accurately measure the Z-axis displacement of the probe. The intersection of the laser beam emitted by the sixth laser interferometer probe and the Z-axis reflector is assumed to be f.

[0070] The measurement results of the laser interferometer measurement module include: the measurement results of the first laser interferometer probe, the measurement results of the second laser interferometer probe, the measurement results of the third laser interferometer probe, the measurement results of the fourth laser interferometer probe, the measurement results of the fifth laser interferometer probe, and the measurement results of the sixth laser interferometer probe. Specifically in this embodiment, the actual three-dimensional displacement of the probe tip relative to the sample surface is calculated based on the measurement results of the laser interferometer measurement module, such as Figure 2 The flowchart shown specifically includes the following steps:

[0071] A1. After the needle tip contacts the sample surface, the intersection of the planes where the X-axis reflector, Y-axis reflector and Z-axis reflector are located is taken as the origin O. The planes where the three reflectors are located are X=0, Y=0 and Z=0 respectively. The initial coordinate system of the load module is established. The initial coordinate system of the load module is regarded as a fixed world coordinate system.

[0072] The intersection of the planes where the reflectors of the three axes X, Y, and Z are located at the initial moment is taken as the origin O, and the planes where the three reflectors are located are X=0, Y=0, and Z=0 to establish the initial coordinate system of the load module at the initial moment. In this coordinate system, the coordinates of the laser reflection points of the laser beams emitted by the six-way laser interferometer probe on the X-axis, Y-axis, and Z-axis reflectors are as follows:

[0073]

[0074] When the three-dimensional orthogonal scanning module starts working, let the laser reflection points at time t be a', b', c', d', e', and f'. Since the three laser beams A, B, and C are parallel to the X-axis, only the X-axis coordinates of a', b', and c' change compared with a, b, and c; since the two laser beams D and E are parallel to the Y-axis, only the Y-axis coordinates of d' and e' change compared with d and e; since the F beam is parallel to the Z-axis after passing through the right-angle reflector, only the Z-axis coordinates of f' change compared with f. Therefore, the coordinates of a', b', c', d', e', and f' can be expressed as follows:

[0075]

[0076] In the formula, Δx a , Δx b , Δx c , Δy d, Δy e , Δz f It is the result measured by each interferometer probe.

[0077] A2. When the three-dimensional orthogonal scanning module drives the probe to scan, the current coordinate system of the load module is determined according to the change of the measurement result of the laser interferometer measurement module; the current coordinate system of the load module reflects the position and posture of the load module in the world coordinate system at the current moment. Figure 3 In the flowchart shown, step A2 specifically includes the following steps:

[0078] A21. According to the changes in the measurement results of the laser interferometer measurement module, determine the equation of the plane where the X-axis reflector is currently located in the world coordinate system and the X-axis vector of the current coordinate system of the load module. Determine the X-axis vector of the current coordinate system of the load module according to the following formula:

[0079]

[0080] Among them, (k1, m1, n1) is the X-axis vector of the current coordinate system of the load module, K1, M1 and N1 are the plane equation coefficients of the plane where the X-axis reflector is currently located; the plane equation of the plane where the X-axis reflector is currently located at time t can be determined by the coordinates of points a', b' and c', and the plane equation coefficients of the plane where the X-axis reflector is currently located can be determined according to the following formula:

[0081]

[0082] Among them, (x a' ,y a ,z a ) is the world coordinate of the laser reflection point of the first laser interferometer probe on the X-axis reflector at the current moment, (x b' ,y b ,z b ) is the world coordinate of the laser reflection point of the second laser interferometer probe on the X-axis reflector at the current moment, (x c' ,y c ,z c ) is the world coordinate of the laser reflection point of the third laser interferometer probe on the X-axis reflector at the current moment.

[0083] A22. According to the change of the measurement result of the laser interferometer measurement module and the X-axis vector of the current coordinate system of the load module, determine the equation of the plane where the Y-axis reflector is currently located in the world coordinate system and the Y-axis vector of the current coordinate system of the load module. Determine the Y-axis vector of the current coordinate system of the load module according to the following formula:

[0084]

[0085] Among them, (k2, m2, n2) is the Y-axis vector of the current coordinate system of the load module, K2, M2 and N2 are the plane equation coefficients of the plane where the Y-axis reflector is currently located; since the Y-axis reflector is always perpendicular to the X-axis reflector, and d' and e' are on the Y-axis reflector at time t, the plane equation of the plane where the Y-axis reflector is currently located at time t can be determined by the coordinates of points d' and e' and the plane equation coefficients of the plane where the X-axis reflector is currently located. Specifically, the plane equation coefficients of the plane where the Y-axis reflector is currently located are determined according to the following formula:

[0086]

[0087] Among them, (x d' ,y d ,z d ) is the world coordinate of the laser reflection point of the fourth laser interferometer probe on the Y-axis reflector at the current moment, (x e' ,y e ,z e ) is the world coordinate of the laser reflection point of the fifth laser interferometer probe on the Y-axis reflector at the current moment.

[0088] A23. According to the change of the measurement result of the laser interferometer measurement module, the X-axis vector of the current coordinate system of the load module and the Y-axis vector of the current coordinate system of the load module, determine the equation of the plane where the Z-axis reflector is currently located in the world coordinate system and the Z-axis vector of the current coordinate system of the load module. Determine the Z-axis vector of the current coordinate system of the load module according to the following formula:

[0089]

[0090] Among them, (k3, m3, n3) is the Z-axis vector of the current coordinate system of the load module, K3, M3 and N3 are the plane equation coefficients of the plane where the Z-axis reflector is currently located; since the Z-axis reflector is always perpendicular to the X-axis reflector and the Y-axis reflector, and f' is on the Z-axis reflector at time t, the plane equation of the plane where the Z-axis reflector is currently located at time t can be determined by the coordinates of point f', the plane equation coefficients of the plane where the X-axis reflector is currently located, and the plane equation coefficients of the plane where the Y-axis reflector is currently located. Specifically, the plane equation coefficients of the plane where the Z-axis reflector is currently located are determined according to the following formula:

[0091]

[0092] Among them, (x f' ,y f ,z f ) is the world coordinate of the laser reflection point of the sixth laser interferometer probe on the Z-axis reflector at the current moment.

[0093] A24. Obtain the coordinates of the origin of the current coordinate system of the load module in the world coordinate system according to the equation of the plane where the X-axis reflector is currently located, the equation of the plane where the Y-axis reflector is currently located, and the equation of the plane where the Z-axis reflector is currently located.

[0094] A25. Determine the current coordinate system of the load module according to the X-axis vector of the current coordinate system of the load module, the Y-axis vector of the current coordinate system of the load module, the Z-axis vector of the current coordinate system of the load module and the origin of the current coordinate system of the load module.

[0095] Assume that the origin of the new load module coordinate system at time t is O'. Since O' is at the intersection of the planes where the three reflectors are located, the point O'(x o' ,y o' ,z o' ) satisfies the following formula:

[0096]

[0097] From this we can solve (x o' ,y o' ,z o' ). Therefore, the translation vector of the new load module coordinate system relative to the initial load module coordinate system at the initial moment is as follows:

[0098]

[0099] A3. According to the load module initial coordinate system and the load module current coordinate system, determine the rotation matrix and translation vector from the load module initial coordinate system to the load module current coordinate system. The rotation matrix from the load module initial coordinate system to the load module current coordinate system is expressed by the following formula:

[0100]

[0101] Among them, R is the rotation matrix from the initial coordinate system of the load module to the current coordinate system of the load module.

[0102] The translation vector from the initial coordinate system of the load module to the current coordinate system of the load module is expressed by the following formula:

[0103]

[0104] Wherein, D is the translation vector from the initial coordinate system of the load module to the current coordinate system of the load module.

[0105] A4. According to the coordinates of the probe tip in the initial coordinate system of the load module, the rotation matrix and translation vector from the initial coordinate system of the load module to the current coordinate system of the load module, the actual three-dimensional displacement of the probe tip relative to the fixed sample from the initial moment to the current moment is calculated. If the coordinates of the probe tip in the initial coordinate system of the load module at the initial moment are defined as P(xP ,y P ,z P ), in this embodiment, the actual three-dimensional displacement of the probe tip relative to the fixed sample from the initial moment to the current moment is calculated according to the following formula:

[0106]

[0107]

[0108] Where S is the actual three-dimensional displacement of the probe tip relative to the fixed sample from the initial moment to the current moment, (x P' ,y P' ,z P' ) is the world coordinate of the probe tip at the current moment, (x P ,y P ,z P ) is the coordinate of the probe tip in the initial coordinate system of the load module at the initial moment, that is, the world coordinate of the probe tip at the initial moment. Since the actual three-dimensional displacement comes from the measurement result of the laser interferometer probe, it can be traced back to the laser wavelength, so the AFM can have a metrological effect.

[0109] The above-mentioned embodiment provided by the present application compensates the Abbe error caused by the displacement measurement axis not passing through the probe tip through the measurement results of the laser interferometer measurement module, and can realize the measurement of the microscopic morphology parameters of the surface of large samples in conjunction with the large-size sample stage, breaking the limitation of the sample size on the traditional metrological atomic force microscope, and can realize the accurate measurement of the microstructure of the surface of large samples; and because of the use of laser interferometer measurement, the size detection results of the atomic force microscope can be traced back to the laser wavelength, which has metrological significance.

[0110] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0111] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A three-dimensional scanning probe for a metrological atomic force microscope, characterized in that: include: A load module, a three-dimensional orthogonal scanning module and a laser interferometer measurement module; the load module is used to fix a probe, a probe force detection unit and a reflector group, and the load module is fixed on the movable part of the three-dimensional orthogonal scanning module; the three-dimensional orthogonal scanning module is used to drive the probe to perform scanning in the X and Y directions and sample morphology feedback in the Z direction relative to the sample on the sample stage; the laser interferometer measurement module is used to emit laser to the reflector group arranged on the load module and obtain the measurement result of the laser interferometer measurement module, so as to solve the actual three-dimensional displacement of the probe tip relative to the sample surface according to the measurement result of the laser interferometer measurement module.

2. The three-dimensional scanning probe of the metrology type atomic force microscope according to claim 1, characterized in that: The load module includes: a probe, a probe holder, a probe force detection unit, a reflector group and a rigid frame; the reflector group includes an X-axis reflector, a Y-axis reflector and a Z-axis reflector; The probe is fixed on the probe holder, and the tip of the probe is located at the lowest point of the three-dimensional scanning probe; the probe holder and the probe force detection unit are both fixed on the rigid frame, and the rigid frame is fixed on the movable part of the three-dimensional orthogonal scanning module; the X-axis reflector and the Y-axis reflector are respectively fixed on two adjacent orthogonal surfaces of the rigid frame, and the reflection surfaces of the X-axis reflector and the Y-axis reflector face outward and are respectively perpendicular to the X-axis and the Y-axis; the Z reflector is fixed on the bottom of the probe holder, and the reflection surface of the Z reflector faces upward and is perpendicular to the Z axis.

3. The three-dimensional scanning probe of the metrology type atomic force microscope according to claim 2, characterized in that: The probe force detection unit adopts an optical lever optical path or a self-sensing circuit according to the type of the probe.

4. The three-dimensional scanning probe of the metrology type atomic force microscope according to claim 2, characterized in that: The three-dimensional orthogonal scanning module comprises: a fixed part and a movable part; the movable part drives the probe of the load module to perform scanning in the X and Y directions and feedback movement in the Z direction relative to the sample on the sample stage.

5. The three-dimensional scanning probe of the metrology type atomic force microscope according to claim 2, characterized in that: The laser interferometer measurement module includes: a first mounting frame, a second mounting frame, a right-angle reflector, a first laser interferometer probe, a second laser interferometer probe, a third laser interferometer probe, a fourth laser interferometer probe, a fifth laser interferometer probe and a sixth laser interferometer probe; the first mounting frame and the second mounting frame are fixedly mounted on the fixing part of the three-dimensional orthogonal scanning module; the first laser interferometer probe, the second laser interferometer probe, the third laser interferometer probe, the fourth laser interferometer probe, the fifth laser interferometer probe and the sixth laser interferometer probe are fixedly mounted on the first mounting frame; the right-angle reflector is fixedly mounted on the second mounting frame, and the right-angle reflector is used to reflect the laser of the sixth laser interferometer probe to the Z-axis reflector; The first laser interferometer probe, the second laser interferometer probe and the third laser interferometer probe are respectively oriented toward the X-axis reflector, and the first laser interferometer probe, the second laser interferometer probe and the third laser interferometer probe respectively emit lasers toward the X-axis reflector and receive reflected light to accurately measure the X-axis displacement of the probe; the three laser points of the first laser interferometer probe, the second laser interferometer probe and the third laser interferometer probe on the X-axis reflector are not collinear; The fourth laser interferometer probe and the fifth laser interferometer probe are respectively facing the Y-axis reflector, and the fourth laser interferometer probe and the fifth laser interferometer probe respectively emit lasers to the Y-axis reflector and receive reflected light, so as to accurately measure the Y-axis displacement of the probe; The sixth laser interferometer probe faces the right-angle reflector, emits laser light to the right-angle reflector, reflects the laser light to the Z-axis reflector through the right-angle reflector, and receives reflected light to accurately measure the Z-axis displacement of the probe.

6. The three-dimensional scanning probe of the metrology type atomic force microscope according to claim 1, characterized in that: The actual three-dimensional displacement of the probe tip relative to the sample surface is calculated based on the measurement result of the laser interferometer measurement module, specifically including: After the needle tip contacts the sample surface, the intersection of the planes where the X-axis reflector, the Y-axis reflector and the Z-axis reflector are located is taken as the origin O, and the planes where the three reflectors are located are X=0, Y=0, and Z=0 respectively, and the initial coordinate system of the load module is established, and the initial coordinate system of the load module is regarded as a fixed world coordinate system; When the three-dimensional orthogonal scanning module drives the probe to scan, the current coordinate system of the load module is determined according to the change of the measurement result of the laser interferometer measurement module, and the current coordinate system of the load module reflects the position and posture of the load module in the world coordinate system at the current moment; Determine a rotation matrix and a translation vector from the initial coordinate system of the load module to the current coordinate system of the load module according to the initial coordinate system of the load module and the current coordinate system of the load module; According to the coordinates of the probe tip in the initial coordinate system of the load module, the rotation matrix and translation vector from the initial coordinate system of the load module to the current coordinate system of the load module, the actual three-dimensional displacement of the probe tip relative to the fixed sample from the initial moment to the current moment is calculated.

7. The three-dimensional scanning probe of the metrology type atomic force microscope according to claim 6, characterized in that: Determining the current coordinate system of the load module according to the change of the measurement result of the laser interferometer measurement module specifically includes: According to the change of the measurement result of the laser interferometer measurement module, determine the equation of the plane where the X-axis reflector is currently located in the world coordinate system and the X-axis vector of the current coordinate system of the load module; According to the change of the measurement result of the laser interferometer measurement module and the X-axis vector of the current coordinate system of the load module, the equation of the plane where the Y-axis reflector is currently located in the world coordinate system and the Y-axis vector of the current coordinate system of the load module are determined; Determine the equation of the plane where the Z-axis reflector is currently located in the world coordinate system and the Z-axis vector of the current coordinate system of the load module according to the change of the measurement result of the laser interferometer measurement module, the X-axis vector of the current coordinate system of the load module, and the Y-axis vector of the current coordinate system of the load module; The coordinates of the origin of the current coordinate system of the load module in the world coordinate system are obtained according to the equation of the plane where the X-axis reflector is currently located, the equation of the plane where the Y-axis reflector is currently located, and the equation of the plane where the Z-axis reflector is currently located; The current coordinate system of the load module is determined according to the X-axis vector of the current coordinate system of the load module, the Y-axis vector of the current coordinate system of the load module, the Z-axis vector of the current coordinate system of the load module and the origin of the current coordinate system of the load module.

8. The three-dimensional scanning probe of the metrology type atomic force microscope according to claim 7, characterized in that: The measurement results of the laser interferometry measurement module include: the measurement results of the first laser interferometry probe, the measurement results of the second laser interferometry probe, the measurement results of the third laser interferometry probe, the measurement results of the fourth laser interferometry probe, the measurement results of the fifth laser interferometry probe and the measurement results of the sixth laser interferometry probe.

9. The three-dimensional scanning probe of the metrology type atomic force microscope according to claim 8, characterized in that: Determine the X-axis vector of the current coordinate system of the load module according to the following formula: Among them, (k1, m1, n1) is the X-axis vector of the current coordinate system of the load module, K1, M1 and N1 are the plane equation coefficients of the plane where the X-axis reflector is currently located; the plane equation coefficients of the plane where the X-axis reflector is currently located are determined according to the following formula: Among them, (x a' ,y a ,z a ) is the world coordinate of the laser reflection point of the first laser interferometer probe on the X-axis reflector at the current moment, (x b' ,y b ,z b ) is the world coordinate of the laser reflection point of the second laser interferometer probe on the X-axis reflector at the current moment, (x c' ,y c ,z c ) is the world coordinate of the laser reflection point of the third laser interferometer probe on the X-axis reflector at the current moment; Determine the Y-axis vector of the current coordinate system of the load module according to the following formula: Among them, (k2, m2, n2) is the Y-axis vector of the current coordinate system of the load module, K2, M2 and N2 are the plane equation coefficients of the plane where the Y-axis reflector is currently located; the plane equation coefficients of the plane where the Y-axis reflector is currently located are determined according to the following formula: Among them, (x d' ,y d ,z d ) is the world coordinate of the laser reflection point of the fourth laser interferometer probe on the Y-axis reflector at the current moment, (x e' ,y e ,z e ) is the world coordinate of the laser reflection point of the fifth laser interferometer probe on the Y-axis reflector at the current moment; Determine the Z-axis vector of the current coordinate system of the load module according to the following formula: Among them, (k3, m3, n3) is the Z-axis vector of the current coordinate system of the load module, K3, M3 and N3 are the plane equation coefficients of the plane where the Z-axis reflector is currently located; the plane equation coefficients of the plane where the Z-axis reflector is currently located are determined according to the following formula: Among them, (x f' ,y f ,z f ) is the world coordinate of the laser reflection point of the sixth laser interferometer probe on the Z-axis reflector at the current moment.

10. The three-dimensional scanning probe of the metrology type atomic force microscope according to claim 9, characterized in that: The rotation matrix from the initial coordinate system of the load module to the current coordinate system of the load module is expressed by the following formula: Among them, R is the rotation matrix from the initial coordinate system of the load module to the current coordinate system of the load module; The translation vector from the initial coordinate system of the load module to the current coordinate system of the load module is expressed by the following formula: Wherein, D is the translation vector from the initial coordinate system of the load module to the current coordinate system of the load module; The actual three-dimensional displacement of the probe tip relative to the stationary sample from the initial moment to the current moment is calculated according to the following formula: Where S is the actual three-dimensional displacement of the probe tip relative to the fixed sample from the initial moment to the current moment, (x P' ,y P' ,z P' ) is the world coordinate of the probe tip at the current moment, (x P ,y P ,z P ) is the coordinate of the probe tip in the initial coordinate system of the load module at the initial moment, that is, the world coordinate of the probe tip at the initial moment.

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