Atomic Force Microscope and Its Probe Calibration Method

Abstract

The present disclosure provides an atomic force microscope and a probe calibration method thereof, relating to the technical field of precision measurement, and is used to solve the technical problem that the acquired image of the atomic force microscope is distorted. The probe calibration method includes setting a target position O on the surface of a sample to be measured; moving the tip of the probe to an initial position A, and the initial position A is directly above the target position O; controlling the tip of the probe to move from the initial position towards the target position O; obtaining the actual position O' when the tip of the probe approaches the surface of the sample to be measured; obtaining the displacement deviation between the target position O and the actual position O', and the displacement deviation includes an offset amount and an offset angle; compensating the initial position A of the tip of the probe according to the displacement deviation. The probe calibration method provided by the present disclosure can compensate for the deviation between the target position and the actual position of the probe, avoid causing distortion of the topography image of the object to be measured, and can improve the analysis effect.

Description

Technical Field

[0001] The present disclosure relates to the field of precision measurement technologies, and in particular, to an atomic force microscope and a probe calibration method thereof. Background Art

[0002] An atomic force microscope (AFM for short) can scan the surface profile of a sample and generate a three-dimensional surface map, and is widely used in the research fields of nano-related disciplines such as semiconductors.

[0003] The atomic force microscope includes a probe cantilever assembly, a laser emitter, a spot position detector, etc. The probe cantilever assembly includes a cantilever and a probe disposed at the end of the cantilever. The laser beam emitted by the laser emitter is focused on the back of the cantilever and reflected from the back of the cantilever to the spot position detector. When scanning a sample, due to the interaction force between the atoms on the surface of the sample and the atoms at the tip of the probe, the cantilever will bend and undulate along with the surface topography of the sample, and the spot formed by the reflected light beam on the spot position detector will also shift accordingly. Then, information about the surface topography of the measured sample can be obtained through the change in the spot position.

[0004] However, when using an atomic force microscope to scan a measured sample, the obtained topography image is distorted, thus affecting the analysis effect. Summary of the Invention

[0005] In view of the above problems, embodiments of the present disclosure provide an atomic force microscope and a probe calibration method thereof, which can compensate for the deviation between the target position and the actual position of the probe, avoid distortion of the topography image of the object to be measured, and improve the analysis effect.

[0006] The first aspect of the embodiments of the present disclosure provides a probe calibration method, including the following steps:

[0007] Set a target position O on the surface of the object to be measured;

[0008] Move the tip of the probe to an initial position A, and the initial position A is directly above the target position O;

[0009] Control the tip of the probe to move from the initial position A towards the target position O;

[0010] Obtain the actual position O' when the tip of the probe approaches the surface of the object to be measured;

[0011] Obtain the displacement deviation between the target position O and the actual position O', and the displacement deviation includes an offset amount and an offset angle;

[0012] Compensate the initial position A of the tip of the probe according to the displacement deviation.

[0013] The probe calibration method provided by the embodiments of the present disclosure has at least the following advantages:

[0014] The probe calibration method provided by the embodiments of the present disclosure sets a target position O on the surface of the sample to be measured, moves the tip of the probe to the initial position directly above the target position, controls the tip of the probe to approach the surface of the sample to be measured from the initial position, and obtains the actual position O'; further obtains the displacement deviation between the actual position O' and the target position.

[0015] Furthermore, before scanning the sample to be measured next time, when setting the initial position of the tip of the probe, compensate for the displacement deviation of the tip of the probe, that is, when setting the initial position of the tip of the probe, compensate for the displacement deviation of the probe in advance to eliminate the displacement deviation of the tip of the probe during the lowering process, thereby completing the calibration of the tip of the probe.

[0016] With such a setting, when scanning and measuring the sample to be measured, it can be ensured that the tip of the probe can move to the target position to accurately obtain the information of the surface topography of the target position, and avoid the phenomenon that the topography image of the sample to be measured is distorted and affects the analysis effect.

[0017] For the probe calibration method as described above, the step of obtaining the actual position O' when the tip of the probe approaches the surface of the sample to be measured includes:

[0018] Judge whether the tip of the probe is close to the surface of the sample to be measured;

[0019] If so, obtain the actual position O' when the tip of the probe is close to the surface of the sample to be measured;

[0020] If not, continue to control the tip of the probe to move towards the surface of the sample to be measured.

[0021] For the probe calibration method as described above, the step of judging whether the tip of the probe is close to the surface of the sample to be measured includes:

[0022] Set a preset pressure value when the tip of the probe is close to the surface of the sample to be measured;

[0023] Use a pressure sensor to obtain the actual pressure value between the tip of the probe and the surface of the sample to be measured;

[0024] Judge whether the actual pressure value is greater than or equal to the preset pressure value;

[0025] If so, judge that the tip of the probe is close to the surface of the sample to be measured;

[0026] If not, continue to control the tip of the probe to move towards the surface of the sample to be measured.

[0027] The probe calibration method as described above, wherein the probe is connected to a scanner, and the scanner is signal-connected to a control feedback system; and the scanner includes a first piezoelectric control module for controlling the probe to move along the X-axis direction, a second piezoelectric control module for controlling the probe to move along the Y-axis direction, and a third piezoelectric control module for controlling the probe to move along the Z-axis direction;

[0028] The step of obtaining the displacement deviation between the target position O and the actual position O' includes:

[0029] When the tip of the probe approaches the sample to be measured, the control feedback system obtains the corresponding coordinate positions of the piezoelectric control modules on the scanner.

[0030] The step of compensating the initial position A of the tip of the probe according to the displacement deviation in the probe calibration method as described above includes:

[0031] Use the first piezoelectric control module and the second piezoelectric control module to control the probe to move along the X-axis direction and the Y-axis direction to compensate for the displacement deviation of the tip of the probe.

[0032] The step of moving the tip of the probe to the initial position A, and the initial position A is directly above the target position O in the probe calibration method as described above includes:

[0033] Establish a three-dimensional angular coordinate system, and set the target position O as the coordinate origin (0, 0, 0);

[0034] Set the coordinates of the initial position A as (0, 0, z);

[0035] Control the tip of the probe to move directly above the target position.

[0036] In the probe calibration method as described above, the target position O is the center of the sample to be measured, and a cross-shaped pattern is set at the target position.

[0037] In the probe calibration method as described above, the coordinates of the actual position O' are obtained as (r, α, 0), where r is the offset between the actual position O' and the coordinate origin, and α is the offset angle;

[0038] The step of compensating the initial position of the tip of the probe according to the displacement deviation includes: controlling the tip of the probe to move to the compensation position B, and the coordinates of the compensation position B are (r, α + π, z).

[0039] For the probe calibration method as described above, after replacing a new probe or before scanning a sample to be measured, the probe is calibrated using the calibration method.

[0040] In a second aspect of the embodiments of the present disclosure, there is provided an atomic force microscope used for the probe calibration method described in the first aspect. The atomic force microscope includes a scanner, a probe cantilever assembly, a control feedback system, and an optical detection system. The probe cantilever assembly includes a cantilever and a probe disposed on the cantilever. The probe is located at one end of the cantilever, and the other end of the cantilever is connected to the scanner. The probe is further provided with a pressure sensor connected to the control feedback system. The optical detection system includes a laser emitter and a spot position detector, and the spot position detector is connected to the control feedback system.

[0041] The atomic force microscope provided by the embodiments of the present disclosure has at least the following advantages:

[0042] For the atomic force microscope provided by the embodiments of the present disclosure, it can compensate the initial position of the tip of the probe for the next time according to the displacement deviation of the tip of the probe during the lowering process, so as to eliminate the displacement deviation generated during the lowering process of the tip. Furthermore, the tip of the probe can be moved to a preset target position to accurately obtain the information of the surface topography at the target position, and avoid the phenomenon that the topography image of the sample to be measured is distorted and affects the analysis effect.

[0043] For the atomic force microscope as described above, the scanner includes a first piezoelectric control module, a second piezoelectric control module, and a third piezoelectric control module that are signal-connected to the control feedback system.

[0044] The first piezoelectric control module includes a first piezoelectric ceramic block for controlling the movement of the cantilever in the X-axis direction, and the second piezoelectric control module includes a second piezoelectric ceramic block for controlling the movement of the cantilever in the Y-axis direction. The third piezoelectric control module includes a third piezoelectric ceramic block for controlling the movement of the cantilever in the Z-axis direction.

[0045] For the atomic force microscope as described above, the cantilever is configured to be made of a silicon wafer or a silicon nitride wafer with a thickness range of 5 μm to 500 μm and a length range of 100 μm to 500 μm.

[0046] For the atomic force microscope as described above, when the atomic force microscope scans the sample to be detected, the distance between the tip of the probe and the surface of the sample to be detected ranges from 5 nm to 10 nm. Description of the Drawings

[0047] To more clearly illustrate the technical solutions in the embodiments of the present disclosure or the prior art, the following will briefly introduce the accompanying drawings required in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are some embodiments of the present disclosure. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can also be obtained based on these drawings.

[0048] Figure 1 Structural schematic diagram of the atomic force microscope provided by the embodiment of the present disclosure;

[0049] Figure 2 Schematic diagram of the tip of the probe approaching the surface of the sample to be measured provided by the embodiment of the present disclosure;

[0050] Figure 3 Flow schematic of the probe calibration method provided by the embodiment of the present disclosure Figure 1 ;

[0051] Figure 4 Flow schematic of the probe calibration method provided by the embodiment of the present disclosure Figure 2 ;

[0052] Figure 5 Flow schematic of the probe calibration method provided by the embodiment of the present disclosure Figure 3 ;

[0053] Figure 6 Schematic diagram of the positions of the target position O, the actual position O', the initial position A, and the compensation position B in a three-dimensional angular coordinate system provided by the embodiment of the present disclosure;

[0054] Figure 7 Schematic diagram of the displacement deviation between the target position O and the actual position O' provided by the embodiment of the present disclosure.

[0055] Explanation of reference numerals:

[0056] 10 - Sample to be measured;

[0057] 20 - Probe;

[0058] 21 - Tip;

[0059] 30 - Scanner;

[0060] 40 - Laser emitter;

[0061] 50 - Spot position detector;

[0062] 60 - Control feedback system. Detailed implementation manners

[0063] As described in the background art, when the existing atomic force microscope scans a sample to be measured, there is a problem of distortion of the topography image of the sample to be measured, which affects the analysis effect. After research by the inventor, it is found that the reason for this problem is that when the tip of the probe moves towards the surface of the sample to be measured, the moving path is offset, resulting in a displacement deviation between the actual position of the probe and the target position. Furthermore, the obtained topography image does not match the topography image of the target position, thus resulting in the problem of distortion.

[0064] Therefore, the embodiment of the present disclosure provides a method for calibrating a probe. By setting a target position O on the surface of the sample to be measured and moving the tip of the probe to an initial position A directly above the target position O, controlling the tip of the probe to approach the surface of the sample to be measured from the initial position A, and obtaining the actual position O'; further obtaining the displacement deviation between the actual position O' and the target position O.

[0065] Therefore, before scanning the sample to be measured next time, when setting the initial position A of the tip of the probe, compensate for the displacement deviation of the tip of the probe to eliminate the displacement deviation during the lowering process of the tip of the probe, thereby completing the calibration of the tip of the probe.

[0066] With such a setting, when using the atomic force microscope to scan and measure the sample to be measured, it can ensure that the tip of the probe can move to the target position to accurately obtain the information of the surface topography of the target position, and avoid the phenomenon that the topography image of the sample to be measured is distorted and affects the analysis effect.

[0067] In order to make the above objects, features, and advantages of the embodiments of the present disclosure more obvious and understandable, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments of the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present disclosure.

[0068] Figure 1 It is a schematic structural diagram of an atomic force microscope provided by an embodiment of the present disclosure; Figure 2 It is a schematic diagram of the tip of the probe approaching the surface of the sample to be measured provided by an embodiment of the present disclosure;

[0069] As Figure 1 and Figure 2 shown, the embodiment of the present disclosure provides a probe calibration method, which is implemented based on an atomic force microscope, that is, this calibration method is applicable to calibrating the probe of an atomic force microscope. For the convenience of introducing the probe calibration method in detail, the atomic force microscope is first introduced in the embodiment of the present disclosure.

[0070] The atomic force display microscope provided by the embodiments of the present disclosure can be a non-contact atomic force microscope or a contact atomic force microscope, and the probe calibration method is applicable to the above-mentioned atomic force microscopes. In this embodiment, taking the non-contact atomic microscope as an example, the calibration method of its probe 20 will be described.

[0071] For a non-contact atomic force microscope, when scanning and measuring the surface of a sample 10 to be measured, the tip 21 of the probe 20 of the non-contact atomic force microscope approaches the surface of the sample 10 to be measured, and the tip 21 of the probe 20 does not contact the surface of the sample 10 to be measured. For example, when the non-contact atomic force microscope scans the sample to be detected, a certain distance is maintained between the tip 21 of the probe 20 and the surface of the sample to be detected, and the distance range between the two is 5 nm to 10 nm.

[0072] Specifically, the non-contact atomic force microscope includes a scanner 30, a probe cantilever assembly, a control feedback system 60, and an optical detection system. The probe cantilever assembly includes a cantilever and a probe 20. The cantilever is used to mount the probe 20 and drive the probe 20 to move. One end of the cantilever is connected to the scanner 30, and the other end of the cantilever is connected with the probe 20. The probe 20 has a tip 21 facing the surface of the sample 10 to be measured, and a micro-sensitive element (such as a pressure sensor) is provided at this tip 21.

[0073] The micro-sensitive element is signal-connected to the above control feedback system 60. The micro-sensitive element is configured to sense the weak interatomic interaction force between the surface of the sample 10 to be measured and the tip 21 to determine whether the tip 21 is approaching the surface of the sample 10 to be measured. When the tip 21 approaches the surface of the sample 10 to be measured, due to the interatomic interaction force between the tip 21 and the surface of the sample 10 to be measured, the cantilever deforms or the motion state changes. Furthermore, the control feedback system 60 determines according to the state change of the cantilever. This state change can be reflected by the coordinate information associated with the cantilever and the spot position associated with the cantilever in the following text, so as to obtain the surface structure and properties of the sample 10 to be measured.

[0074] Furthermore, the tip 21 of the probe 20 in the embodiments of the present disclosure is located above the sample 10 to be measured and maintains a certain distance from the upper surface of the sample 10 to be measured, that is, the tip 21 of the probe 20 does not contact the upper surface of the sample 10 to be measured. The scanner 30 can control the tip 21 of the probe 20 to move towards the sample 10 to be measured, and the tip 21 can approach the upper surface of the sample 10 to be measured. When the tip 21 approaches the upper surface of the sample 10 to be measured, the scanner 30 controls the probe 20 to move on the upper surface of the sample 10 to be measured, so as to obtain the overall structural morphology of the upper surface of the sample 10 to be measured.

[0075] The scanner 30 is also used to control the movement of the cantilever and can keep the tip 21 close to the sample 10 to be measured and control the probe 20 to scan the surface of the sample 10 to be measured. The scanner 30 includes a first piezoelectric control module, a second piezoelectric control module, and a third piezoelectric control module, and each piezoelectric control module is respectively connected to the control feedback system 60 by signal.

[0076] Exemplarily, the scanner 30 includes a body. The first piezoelectric control module may be a first piezoelectric ceramic block disposed on the body. The first piezoelectric control module is connected to the control feedback system 60 by signal. The control feedback system 60 can send an action signal to the first piezoelectric ceramic block and control the cantilever to move along the X-axis direction through the first piezoelectric ceramic block; conversely, the control feedback system 60 can obtain the state of the first piezoelectric ceramic block in real time and further obtain the coordinate information of the tip 21 of the cantilever in the X-axis direction at this time.

[0077] The second piezoelectric control module may be a second piezoelectric ceramic block disposed on the body. Similarly, the second piezoelectric ceramic block is connected to the control feedback system 60 by signal. The control feedback system 60 can send an action signal to the second piezoelectric ceramic block and control the cantilever to move along the Y-axis direction through the second piezoelectric ceramic block; conversely, the control feedback system 60 can obtain the state of the second piezoelectric ceramic block and further obtain and judge the coordinate information of the tip 21 of the cantilever in the Y-axis direction at this time.

[0078] Similarly, the third piezoelectric control module may be a third piezoelectric ceramic block disposed on the body. Similarly, the third piezoelectric ceramic block is connected to the control feedback system 60 by signal. The control feedback system 60 can send an action signal to the third piezoelectric ceramic block and control the cantilever to move along the Z-axis direction through the third piezoelectric ceramic block; conversely, the control feedback system 60 can obtain the state of the third piezoelectric ceramic block and further obtain and judge the coordinate information of the tip 21 of the cantilever in the Z-axis direction at this time.

[0079] It should be noted that the plane formed by the X-axis direction and the Y-axis direction is the top surface of the scanner 30, and this top surface may be a horizontal plane; the Z-axis direction is perpendicular to the top surface of the scanner 30, and the probe 20 moves toward the surface of the sample 10 to be measured along the Z-axis direction and approaches the sample 10 to be measured. During the scanning measurement of the sample 10 to be measured, the scanner 30 controls the tip 21 of the probe 20 to always be in a close state with the surface of the sample 10 to be measured, so as to ensure that the tip 21 of the probe 20 continuously measures the surface of the sample 10 to be measured.

[0080] The optical detection system provided in the embodiments of the present disclosure includes a laser emitter 40 and a spot position detector 50, wherein the laser emitter 40 and the spot position detector 50 are each connected to a control feedback system 60. The laser emitter 40 is positioned on the side of the cantilever facing away from the sample 10 to be measured, and a certain distance is maintained between the laser emitter 40 and the cantilever. The laser beam emitted by the laser emitter 40 is focused on the back of the cantilever, that is, the laser beam can be irradiated on the back of the cantilever. After being reflected by the back of the cantilever, the laser beam can be further transmitted to the spot position detector 50.

[0081] The spot position detector 50 is typically located on one side of the laser emitter 40. It is used to receive the laser beam reflected by the back of the cantilever, forming a spot on the spot position detector 50. When a non-contact atomic force microscope is used to scan the sample 10 to be tested, the cantilever will bend and fluctuate with the surface topography of the sample 10 due to the interaction force between the atoms on the surface of the sample 10 and the atoms at the tip 21 of the probe 20. That is, as the tip 21 of the cantilever moves across the surface of the sample 10, the cantilever deforms, and the spot formed by the reflected light beam on the spot position detector 50 will also shift accordingly.

[0082] The control feedback system 60 can detect changes in the light spot position and record the electrical signal. The control feedback system 60 uses the electrical signal of the light spot position change as an action signal for the scanner 30 to adjust the movement of each piezoelectric ceramic block so that the tip 21 remains close to the surface of the sample 10 to be tested. Furthermore, the control feedback system 60 can obtain information about the surface morphology of the sample to be tested based on the recorded light spot position changes and analyze them.

[0083] Furthermore, in the disclosed embodiment, the cantilever can be made of a silicon wafer or silicon nitride wafer having a thickness ranging from 5 μm to 500 μm and a length ranging from 100 μm to 500 μm. This configuration provides the cantilever with good elasticity. When the tiny interatomic interaction force between the cantilever tip 21 and the surface of the sample 10 acts on the cantilever, the cantilever vibrates or deforms, causing the light spot formed on the light spot position detector 50 to shift, thereby improving the accuracy of obtaining surface topography information of the sample.

[0084] Figure 3 Schematic diagram of the process of the probe calibration method provided in the embodiment of the present disclosure Figure 1 , Figure 6 Schematic diagram of the positions of the target position O, actual position O', initial position A, and compensated position B in a three-dimensional angular coordinate system provided in an embodiment of the present disclosure.

[0085] like Figure 3 and Figure 6 As shown, the probe calibration method for the non-contact atomic force microscope includes the following steps:

[0086] Step S100: Set a target position O on the surface of the sample 10 to be measured.

[0087] Specifically, set the target position on the upper surface of the sample 10 to be measured, and control the tip 21 of the probe 20 by the scanner 30 of the non-contact atomic force microscope to approach the upper surface of the sample 10 to be measured, so as to obtain the coordinate information of the target position and record it in the control feedback system 60. For the convenience of describing the implementation process of this method, this target position can be defined as the target position O, that is, the target position O can be any position on the surface of the sample 10 to be measured, and the embodiments of the present disclosure do not limit this.

[0088] Step S200: Move the tip 21 of the probe 20 to the initial position A, and the initial position A is directly above the target position O.

[0089] Specifically, the control feedback system 60 controls the scanner 30 to move the tip 21 of the probe 20 to directly above the target position O according to the coordinate information of the target position O. This position can be defined as the initial position A of the scanner 30, that is, the initial position A is directly above the target position O, and the coordinate information of the initial position A is recorded in the control feedback system 60.

[0090] For example, in the embodiment of the present disclosure, the non-contact atomic force microscope is provided with a three-dimensional angular coordinate system. Preferably, for the convenience of obtaining the displacement deviation between the target position O and the actual position O', the target position O is set as the coordinate origin (0, 0, 0) in the embodiment of the present disclosure; the coordinates of the set initial position A are (0, 0, z); further control the tip 21 of the probe 20 to move to the initial position A, and at this time, the tip 21 of the probe 20 is directly above the target position O.

[0091] It should be noted that since the height at which the tip 21 of the probe 20 is located is different, the displacement offset during the lowering of the tip 21 is also different. Therefore, in the whole implementation process of the calibration method provided by the embodiments of the present disclosure, the height at which the tip 21 of the probe 20 is located is the same; in other words, on the premise that the tip 21 of the probe 20 is at the same preset height, the displacement deviation of the tip 21 of the probe 20 in the X direction and the Y-axis direction is calibrated.

[0092] Step S300: Control the tip 21 of the probe 20 to move from the initial position A towards the target position O.

[0093] Specifically, the control feedback system 60 controls the movement of the tip 21 of the probe 20 in the Z-axis direction through the scanner 30, so that the tip 21 of the probe 20 moves towards the target position O, and the tip 21 of the probe 20 approaches the surface of the sample 10 to be measured. When the tip 21 of the probe 20 approaches the surface of the sample 10 to be measured, the distance between the tip 21 of the probe 20 and the surface of the sample 10 to be measured can be 5 nm to 10 nm at this time.

[0094] Step S400: Obtain the actual position O' when the tip 21 of the probe 20 approaches the surface of the sample 10 to be measured.

[0095] Specifically: To obtain the position information of the above actual position O', it is necessary to determine whether the tip 21 of the probe 20 is close to the surface of the sample 10 to be measured, that is, it is necessary to obtain the actual position O' of the tip 21 of the probe 20 on the surface of the sample 10 to be measured in the state where the tip 21 of the probe 20 is close to the sample 10 to be measured.

[0096] Figure 4 Flow schematic of the probe calibration method provided by the embodiment of the present disclosure Figure 2 ; Figure 5 Flow schematic of the probe calibration method provided by the embodiment of the present disclosure Figure 3 , Figure 4 、 Figure 5 It is also a schematic diagram of the specific implementation process of obtaining the actual position O' when the tip 21 of the probe 20 approaches the sample 10 to be measured.

[0097] As Figure 4 shown, step S400 includes step S410: Determine whether the tip 21 of the probe 20 is close to the surface of the sample 10 to be measured; if so, execute step S420: Obtain the actual position when the tip 21 of the probe 20 is close to the surface of the sample 10 to be measured, that is, obtain the coordinate information of the actual position O. If not, continue to execute step S300: Control the tip 21 of the probe 20 to continue to move in the Z-axis direction until the tip 21 of the probe 20 is close to the surface of the sample 10 to be measured.

[0098] In some embodiments, as Figure 5 shown, the above step S410 includes step S411: Set a preset pressure value when the tip 21 of the probe 20 is close to the surface of the sample 10 to be measured.

[0099] Specifically, since a pressure sensor is also provided in the cantilever assembly and the pressure sensor is connected to the control feedback system 60, a preset pressure value when the tip 21 of the probe 20 is close to the surface of the sample 10 to be measured can be set in the control feedback system 60, so as to facilitate the determination of whether the tip 21 of the probe 20 is close to the surface of the sample 10 to be measured.

[0100] Step S412: Use a pressure sensor to obtain the actual pressure value between the tip 21 of the probe 20 and the surface of the sample 10 to be measured.

[0101] Specifically, during the process of the tip 21 of the probe 20 moving towards the surface of the sample 10 to be measured, use the pressure sensor to measure the actual pressure value between the tip 21 of the probe 20 and the surface of the sample 10 to be measured, and transmit the measurement result to the control feedback system 60, so that the control feedback system 60 can compare the actual pressure value with the preset pressure value to determine whether the tip 21 of the probe 20 is close to the surface of the sample 10 to be measured.

[0102] Step S413: Determine whether the actual pressure value is greater than or equal to the preset pressure value.

[0103] Specifically, after the control feedback system 60 receives the actual pressure value detected by the pressure sensor, compare the actual pressure value with the preset pressure value; if the actual pressure value is greater than or equal to the preset pressure value, it is determined that the tip 21 of the probe 20 is close to the surface of the sample 10 to be measured, and step S420 is executed: Obtain the actual position O' when the tip 21 of the probe 20 is close to the surface of the sample 10 to be measured.

[0104] Conversely, if the actual pressure value is less than the preset pressure value, it is determined that the tip 21 of the probe 20 is not close to the surface of the sample 10 to be measured, and step S300 is continued to be executed: Control the tip 21 of the probe 20 to move from the initial position A towards the target position O until the actual pressure value between the tip 21 of the probe 20 and the surface of the sample 10 to be measured is greater than or equal to the preset pressure value and then stop.

[0105] After obtaining the coordinate information of the actual position O', step S500 is executed: Obtain the displacement deviation between the target position O and the actual position O', where the displacement deviation includes an offset and an offset angle.

[0106] Specifically, when the actual pressure between the tip 21 of the probe 20 and the surface of the sample 10 to be measured is greater than or equal to the preset pressure value, the control feedback system 60 obtains the corresponding coordinate positions of the first piezoelectric control module, the second piezoelectric control module, and the third piezoelectric control module in this state to obtain the coordinate information of the actual position O' in this state.

[0107] Since the coordinate information of the target position O is preset in the control feedback system 60, the control feedback system 60 calculates the displacement deviation between the actual coordinate position O' and the target position O according to the coordinate information of the actual position O' and the preset coordinate information of the target position O, where the above displacement deviation includes an offset and an offset angle.

[0108] In some other embodiments, when the actual pressure between the tip 21 of the probe 20 and the surface of the sample 10 to be measured is greater than or equal to a preset pressure value, the control feedback system 60 can obtain the spot position recorded by the spot position sensor, and then the control feedback system 60 can read the coordinate information of the actual position O' through the spot position. This embodiment does not limit this.

[0109] Specifically, in step S100, a target position O is set on the surface of the sample 10 to be measured, and the tip 21 can be controlled to approach the target position O. At this time, the position information of the target position O is obtained by using the optical detection system. For example, after the tip 21 approaches the target position O, the spot position of the spot on the spot position detector 50 under this device is obtained, and the control feedback system 60 is controlled and the coordinate information of the target position O is obtained accordingly; when the tip 21 approaches the actual target position O', the spot position of the spot on the spot position detector 50 in this state is obtained, and the control feedback system 60 is controlled to obtain the coordinate information of the actual target position O' in this state. The control feedback system 60 can obtain the displacement deviation between the two according to the coordinate information of the initial target position O and the coordinate information of the actual target position O'.

[0110] Of course, among the two different methods for obtaining the displacement deviation of the tip 21 provided in the above embodiments, either one can be selected for application, and this disclosure embodiment does not limit this. Or, this disclosure embodiment can simultaneously adopt the above two different methods to obtain the displacement deviation of the tip 21, so as to facilitate the comparison and calibration of the displacement deviation in the subsequent process, that is, the error between the displacement deviations obtained by the two different methods can be further obtained, and it is judged whether the error is within the error range, so as to obtain a more accurate displacement deviation, thereby improving the calibration effect of the tip 21 of the probe 20 and accurately obtaining the information of the surface topography of the sample 10 to be measured.

[0111] Step S600: Compensate the initial position A of the tip 21 of the probe 20 according to the displacement deviation.

[0112] Specifically, after the control feedback system 60 obtains the displacement deviation between the target position O and the actual position O', this displacement deviation can be stored. Before the probe 20 scans the sample 10 to be measured, the initial position A of the tip 21 of the probe 20 can be compensated.

[0113] Figure 7 This is a schematic diagram of the displacement deviation between the target position O and the actual position O' provided by this disclosure embodiment.

[0114] Such as Figure 6 and Figure 7As shown, the coordinates of the actual position O' are obtained as (r, α, 0), where r is the offset between the actual position O' and the origin of coordinates, and α is the offset angle; when compensating for the initial position A of the tip 21 of the probe 20, the tip 21 of the probe 20 can be controlled to move to the compensation position B, and the coordinates of the compensation position B are (r, α + π, z).

[0115] Exemplarily, the control feedback system 60 controls the first piezoelectric module to act according to the displacement deviation between the obtained target position O and the actual position O', so that the cantilever drives the probe 20 to move along the X-axis direction, and controls the second piezoelectric module to act, so that the cantilever drives the probe 20 to move along the Y-axis direction, so that the tip 21 of the probe 20 moves to the compensation position B to eliminate the displacement deviation of the tip 21 of the probe 20 during the lowering process, thereby completing the calibration of the tip 21 of the probe 20.

[0116] With such a setting, when calibrating the probe 20 using the above calibration method, it can be ensured that the tip 21 of the probe 20 can move to the target position when scanning and measuring the sample 10 to be measured, so as to accurately obtain the information of the surface topography of the target position, and avoid the occurrence of the phenomenon that the topography image of the sample to be measured is distorted and affects the analysis effect.

[0117] Continue to refer to Figure 6 , further, the above target position O can be set at the center of the upper surface of the sample 10 to be measured. Compared with the target position O being set at the edge position of the upper surface of the sample 10 to be measured, setting the target position O at the center of the upper surface of the sample 10 to be measured can ensure that the actual position O' does not deviate from the upper surface of the sample 10 to be measured, so as to ensure that the position information of the actual position O' can be obtained and improve the reliability of the calibration implementation of the probe 20.

[0118] In some embodiments, a cross-shaped pattern is provided on the upper surface of the sample 10 to be measured. The cross-shaped pattern is provided at the center position of the upper surface. The cross-shaped pattern can be a fluorescent marker or others. A cross-shaped pattern is provided on the upper surface of the sample 10 to be measured to facilitate the alignment of the tip 21 of the probe 20 with the center of the sample 10 to be measured and improve the alignment efficiency between the tip 21 and the target position O. Further, the probe 20 can be controlled to move along the Z-axis direction. When the tip 21 of the probe 20 approaches the surface of the sample 10 to be measured, it is convenient to obtain the coordinate information of the actual position O'.

[0119] It should be noted that, in some embodiments, before scanning the next sample 10 to be measured using a non-contact atomic force microscope, or after replacing the probe 20, it is necessary to calibrate the tip 21 of the probe 20 once to accurately obtain information on the surface topography of the sample 10 to be measured. Further, the height of the initial position of the tip 21 before and after calibration is the same. Therefore, after calibration, when scanning the sample 10 to be measured, it is only necessary to compensate for the displacement deviation of the tip 21 of the probe 20 in the X-axis direction and the Y-axis direction.

[0120] The embodiments or implementation manners in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The same or similar parts among the various embodiments can be referred to each other.

[0121] In the description of this specification, the descriptions with reference to terms such as "one implementation manner", "some implementation manners", "illustrative implementation manner", "example", "specific example", or "some examples" mean that the specific features, structures, materials, or characteristics described in connection with the implementation manner or example are included in at least one implementation manner or example of the present disclosure. In this specification, the schematic expressions of the above terms do not necessarily refer to the same implementation manner or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more implementation manners or examples.

[0122] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present disclosure, rather than to limit them; although the present disclosure has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the various embodiments of the present disclosure.

Claims

1. A probe calibration method, characterized in that, It includes the following steps: Set a target position O on the surface of the sample to be measured; Move the tip of the probe to the initial position A, and the initial position A is directly above the target position O; Control the tip of the probe to move from the initial position A towards the target position O; Obtain the actual position O' when the tip of the probe approaches the surface of the sample to be measured; Obtain the displacement deviation between the target position O and the actual position O', and the displacement deviation includes an offset and an offset angle; Compensate the initial position A of the tip of the probe according to the displacement deviation.

2. The probe calibration method according to claim 1, wherein The step of obtaining the actual position O' when the tip of the probe approaches the surface of the sample to be measured includes: Judge whether the tip of the probe is close to the surface of the sample to be measured; If so, obtain the actual position O' when the tip of the probe approaches the surface of the sample to be measured; If not, continue to control the tip of the probe to move towards the surface of the sample to be measured.

3. The probe calibration method according to claim 2, wherein The step of judging whether the tip of the probe is close to the surface of the sample to be measured includes: Set a preset pressure value when the tip of the probe is close to the surface of the sample to be measured; Use a pressure sensor to obtain the actual pressure value between the tip of the probe and the surface of the sample to be measured; Judge whether the actual pressure value is greater than or equal to the preset pressure value; If so, judge that the tip of the probe is close to the surface of the sample to be measured; If not, continue to control the tip of the probe to move towards the surface of the sample to be measured.

4. The probe calibration method according to claim 3, wherein The probe is connected to a scanner, and the scanner is signal-connected to a control feedback system; and the scanner includes a first piezoelectric control module for controlling the probe to move in the X-axis direction, a second piezoelectric control module for controlling the probe to move in the Y-axis direction, and a third piezoelectric control module for controlling the probe to move in the Z-axis direction; The step of obtaining the displacement deviation between the target position O and the actual position O' includes: When the tip of the probe is close to the surface of the sample to be measured, the control feedback system obtains the corresponding coordinate positions of the piezoelectric control modules on the scanner.

5. The probe calibration method according to claim 4, wherein The step of compensating the initial position A of the tip of the probe according to the displacement deviation includes: Use the first piezoelectric control module and the second piezoelectric control module to control the probe to move in the X-axis direction and the Y-axis direction to compensate for the displacement deviation of the tip of the probe.

6. The probe calibration method according to any one of claims 1 to 5, characterized in that The step of moving the tip of the probe to the initial position, and the initial position A is directly above the target position O includes: Establish a three-dimensional angular coordinate system, and set the target position O as the coordinate origin (0, 0, 0); Set the coordinates of the initial position A as (0, 0, z); Control the tip of the probe to move directly above the target position O.

7. The probe calibration method according to claim 6, characterized in that The target position O is the center of the sample to be measured, and a cross-shaped pattern is set at the target position.

8. The probe calibration method according to claim 6, wherein The coordinates of the obtained actual position O' are (r, α, 0), where r is the offset between the actual position O' and the coordinate origin, and α is the offset angle; The step of compensating the initial position A of the tip of the probe according to the displacement deviation includes: controlling the tip of the probe to move to the compensation position B, and the coordinates of the compensation position B are (r, α + π, z).

9. The probe calibration method according to claim 1, wherein After replacing a new probe or before scanning a sample to be measured, the probe is calibrated by using the calibration method.

10. An atomic force microscope used in the probe calibration method according to any one of claims 1 to 9, characterized in that, The atomic force microscope includes a scanner, a probe cantilever assembly, a control feedback system, and an optical detection system; The probe cantilever assembly includes a cantilever and a probe disposed on the cantilever. The probe is located at one end of the cantilever, and the other end of the cantilever is connected to the scanner; the probe is further provided with a pressure sensor connected to the control feedback system; The optical detection system includes a laser emitter and a spot position detector, and the spot position detector is connected to the control feedback system.

11. The atomic force microscope according to claim 10, characterized in that, The scanner includes a first piezoelectric control module, a second piezoelectric control module, and a third piezoelectric control module that are signal-connected to the control feedback system; The first piezoelectric control module includes a first piezoelectric ceramic block for controlling the movement of the cantilever in the X-axis direction, and the second piezoelectric control module includes a second piezoelectric ceramic block for controlling the movement of the cantilever in the Y-axis direction; the third piezoelectric control module includes a third piezoelectric ceramic block for controlling the movement of the cantilever in the Z-axis direction.

12. The atomic force microscope according to claim 10, characterized in that, The cantilever is configured to be made of a silicon wafer or a silicon nitride wafer with a thickness range of 5 μm to 500 μm and a length range of 100 μm to 500 μm.

13. The atomic force microscope according to claim 12, characterized in that, The probe is configured such that when the atomic force microscope scans a sample to be detected, the distance between the tip of the probe and the surface of the sample to be detected ranges from 5 nm to 10 nm.

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