Scanning method and device of scanning probe microscope based on high-speed instantaneous force control

Abstract

The application provides a scanning method of a scanning probe microscope based on high-speed instantaneous force control, wherein the scanning probe microscope comprises a probe unit, the method comprises the following steps: acquiring an action force signal between the probe unit and a sample; calculating a real amplitude signal according to the action force signal; acquiring a set amplitude signal; acquiring a first sinusoidal signal; and obtaining a target action force signal according to the real amplitude signal, the set amplitude signal and the first sinusoidal signal; and scanning the surface of the sample according to a target sample scanning mode indicated by the target action force signal; the target sample scanning mode represents a working mode of scanning the surface of the sample under the indication of the target action force signal. The method solves the problems of low tapping frequency of peak force and limited scanning range, and realizes high-speed instantaneous force tapping and mechanical property measurement while ensuring the scanning range.

Description

Technical Field

[0001] This invention relates to the field of scanning probe microscopy, and more particularly to a scanning method and apparatus for scanning probe microscopy based on high-speed instantaneous force control. Background Technology

[0002] Currently, the fastest peak force tapping mode on the market is achieved by Bruker's Dimension Fast Scan, which scans at a peak force tapping frequency of 8kHz. However, its maximum scan area is only 35µm x 35µm. Furthermore, Dimension Fast Scan achieves its faster scanning speed through significant modifications to the previous generation of the scanner head. Also, the 8kHz peak force tapping frequency is only four times higher than the original 2kHz, resulting in a very limited speed improvement.

[0003] Fantner's group at the Swiss Federal Institute of Technology in Lausanne (EPFL) achieved a peak force tapping frequency of 100 kHz by replacing the traditional peak force tapping method with a photothermal effect-driven approach. However, the drawback is that the scanning range is very small, only 1.8 μm x 1.8 μm.

[0004] Therefore, simultaneously increasing the probe modulation frequency without reducing the scanning range has become a key technical challenge that those skilled in the art urgently need to address. Summary of the Invention

[0005] This invention provides a scanning method and apparatus for a scanning probe microscope based on high-speed instantaneous force control, in order to solve the problems of low peak force tapping frequency and limited scanning range.

[0006] According to a first aspect of the present invention, a scanning method for a scanning probe microscope based on high-speed instantaneous force control is provided, comprising the following steps:

[0007] The force signal between the probe unit and the sample is acquired; the force signal characterizes the change of the force on the sample over time.

[0008] The true amplitude signal is calculated based on the applied force signal; the true amplitude signal represents the amplitude of the applied force signal.

[0009] Obtain the set amplitude signal;

[0010] Obtain the first sine wave signal; and obtain the target force signal based on the actual amplitude signal, the set amplitude signal, and the first sine wave signal;

[0011] The surface of the sample is scanned in a target sample scanning mode based on the target force signal; the target sample scanning mode characterizes the working mode of scanning the sample surface under the instruction of the target force signal.

[0012] Optionally, the true amplitude signal is calculated based on the force signal, and the specific steps include:

[0013] A second sine wave signal is acquired, and a background signal is generated based on the second sine wave signal under the triggering of the force signal.

[0014] A first force signal is obtained based on the background signal and the force signal; the first force signal represents the first true force signal after subtracting the background signal.

[0015] An average baseline signal is obtained based on the first force signal; the average baseline signal characterizes the average baseline of the first force signal.

[0016] A second force signal is obtained based on the average baseline signal and the first force signal; the second force signal represents the second true force signal obtained by subtracting the average baseline signal from the first force signal;

[0017] A third force signal is obtained based on the second force signal; the third force signal represents the third true force signal after the second force signal takes a positive value;

[0018] The true amplitude signal is obtained based on the third force signal.

[0019] Optionally, the true amplitude signal is calculated based on the force signal, and the specific steps include:

[0020] Obtain the third sine wave signal;

[0021] A fourth force signal is obtained based on the third sinusoidal signal and the force signal, and the fourth force signal represents the signal obtained by mixing and multiplying the force signal and the third sinusoidal signal.

[0022] The true amplitude signal is obtained based on the fourth force signal, and the true amplitude signal represents the amplitude of the force signal.

[0023] Optionally, a first sine wave signal is obtained; the target force signal is obtained based on the actual amplitude signal, the set amplitude signal, and the first sine wave signal. The specific steps are as follows:

[0024] An error signal is obtained based on the true amplitude signal and the set amplitude signal; the error signal characterizes the error information between the true amplitude signal and the set amplitude signal.

[0025] The control signal is obtained based on the error signal;

[0026] Obtain the first sine wave signal;

[0027] The target force signal is obtained based on the first sine signal and the control signal.

[0028] Optionally, the specific steps for obtaining the interaction force signal between the probe unit and the sample include:

[0029] Obtain the target force signal;

[0030] The target sample is scanned according to the target force signal in the scanning mode.

[0031] During the scanning process of the target sample scanning mode, the scanning process is detected, and the force signal is generated.

[0032] According to a second aspect of the present invention, a method for measuring mechanical properties based on scanning probe microscopy is provided for measuring the mechanical properties of a sample surface, the method comprising the following steps:

[0033] According to any one of the first aspects of the present invention, the scanning method of the scanning probe microscope based on high-speed instantaneous force control scans the surface of the sample, forms a scanning motion, and obtains a force signal, wherein the force signal characterizes the characteristics of the force signal changing with time.

[0034] A quantitative value is obtained based on the force signal; the quantitative value characterizes the surface features of the sample.

[0035] Optionally, a quantitative value is obtained based on the sample scanning signal, and the specific steps include:

[0036] The fifth force signal is obtained based on the sample scanning signal; the fifth force signal characterizes the variation of the force acting on the sample with the distance between the sample and the force-applying party;

[0037] Several quantitative values ​​are determined based on the contact machinery model and the fifth force signal.

[0038] Optionally, the quantitative value includes: van der Waals force and / or capillary adhesion between the sample and the force-applying party.

[0039] According to a third aspect of the present invention, a scanning apparatus for a scanning probe microscope based on high-speed instantaneous force control is provided, comprising:

[0040] The module includes a scanning module, a true amplitude calculation module, a set amplitude generation module, and a target force signal generation module.

[0041] One end of the scanning module is connected to one end of the true amplitude calculation module, and the other end of the scanning module is connected to one end of the target force signal generation module; the other end of the target force signal generation module is connected to the other end of the true amplitude calculation module and the set amplitude generation module.

[0042] The scanning module is used to scan the sample surface to generate a force signal and send the force signal to the real amplitude calculation module.

[0043] The true amplitude calculation module is used to obtain the true amplitude signal based on the force signal and send the true amplitude signal to the target force signal generation module;

[0044] The set amplitude generation module is used to generate a set amplitude signal and send the set amplitude signal to the target force signal generation module;

[0045] The target force signal generation module is used to generate a target force signal using the real amplitude signal and the set amplitude signal, and send it to the scanning module; thereby controlling the scanning module to perform scanning work in the target sample scanning mode according to the target force signal.

[0046] Optionally, the scanning module specifically includes:

[0047] The beam transmitting unit, signal detection unit, longitudinal piezoelectric driving unit, probe holding unit, probe cantilever beam unit, and probe unit are all included.

[0048] In this configuration, one end of the probe unit is mounted in the probe holding unit, the probe cantilever beam unit is connected to the probe holding unit and supports the probe unit, and the other end of the probe unit extends out of the probe cantilever beam unit; one end of the longitudinal piezoelectric drive unit is connected to the probe holding unit, and the other end of the longitudinal piezoelectric drive unit is connected to the target force signal generation module; the signal detection unit is connected to one end of the true amplitude calculation module.

[0049] The probe unit is used to periodically apply a certain force to the surface of the sample; and the probe unit is controlled by the longitudinal piezoelectric drive unit.

[0050] The longitudinal piezoelectric drive unit is used to drive the probe unit to operate in the target sample scanning mode using the received target sample scanning signal;

[0051] The beam transmitting unit is used to transmit a beam to the probe cantilever beam unit;

[0052] The probe cantilever beam unit is used to support the probe unit together with the probe holding unit, and to reflect the received beam transmitted by the beam transmitting unit into the signal detection unit;

[0053] The signal detection unit is used to generate the sample scanning signal based on the reflected beam detected on the probe cantilever beam unit, and send it to the mechanical characteristic calculation module and the true amplitude calculation module.

[0054] Optionally, the true amplitude calculation module specifically includes:

[0055] The system comprises a background generation unit, a first comparison unit, a baseline averaging unit, a second comparison unit, a signal positive conversion unit, a second integration unit, and a sine signal generation unit.

[0056] One end of the background generation unit is connected to the signal detection unit, and the other end of the background generation unit is connected to one end of the first comparison unit and one end of the sine wave signal generation unit; one end of the first comparison unit is also connected to the signal detection unit, and the other end of the first comparison unit is connected to one end of the baseline averaging unit and one end of the second comparison unit; the other end of the baseline averaging unit is connected to one end of the second comparison unit; the other end of the second comparison unit is connected to one end of the signal positive conversion unit; the other end of the signal positive conversion unit is connected to one end of the second integration operation unit; the other end of the second integration operation unit is connected to the target force signal generation module.

[0057] The sinusoidal signal generating unit is used to generate a first sinusoidal signal, a second sinusoidal signal, or a third sinusoidal signal, and send the second sinusoidal signal or the third sinusoidal signal to the real amplitude calculation module, and send the first sinusoidal signal to the target force signal generating module;

[0058] The background generation unit is configured to, when receiving the force signal, trigger the background generation unit to generate a background signal based on the received second sine signal, and send the background signal to the first comparison unit;

[0059] The first comparison unit is configured to obtain a first force signal based on the received background signal and the force signal, and send the first force signal to the baseline averaging analysis unit and the second comparison unit;

[0060] The baseline averaging analysis unit is used to generate an average baseline signal based on the received first force signal, and send the average baseline signal to the second comparison unit;

[0061] The second comparison unit is configured to obtain a second force signal based on the received average baseline signal and the first force signal, and send the second force signal to the signal correction unit;

[0062] The signal positive unit is used to obtain a third force signal based on the second force signal and send the third force signal to the second integration unit;

[0063] The second integration unit is used to obtain the true amplitude signal based on the third force signal and send the true amplitude signal to the target force signal generation module.

[0064] Optionally, the true amplitude calculation module specifically includes:

[0065] Phase-sensitive detection unit and low-pass filter unit;

[0066] One end of the phase-sensitive detection unit is connected to the signal detection unit, the other end of the phase-sensitive detection unit is connected to one end of the low-pass filter unit, and the other end of the low-pass filter unit is connected to the target force signal generation module.

[0067] The phase-sensitive detection unit is used to obtain a fourth force signal based on the received force signal and the third sine signal, and send the fourth force signal to the low-pass filter unit.

[0068] A low-pass filter unit is used to obtain the true amplitude signal based on the fourth force signal and send the true amplitude signal to the target force signal generation module.

[0069] Optionally, the target force signal generation module specifically includes:

[0070] The third comparison unit, the control signal generation unit, and the summation unit;

[0071] One end of the third comparison unit is connected to the other end of the true amplitude calculation module and the set amplitude calculation module; the other end of the third comparison unit is connected to one end of the control signal generation unit; the other end of the control signal generation unit is connected to one end of the summing unit; the other end of the summing unit is connected to the other end of the longitudinal electric drive unit and the other end of the sine signal generation unit.

[0072] The third comparison unit is used to generate an error signal based on the true amplitude signal and the set amplitude signal, and send the error signal to the control signal generation unit;

[0073] The control signal generation unit is used to generate a control signal based on the error signal and send the control signal to the summing unit;

[0074] The summing unit is used to generate the target force signal based on the first sine signal and the control signal, and send the target force signal to the scanning module.

[0075] According to a fourth aspect of the present invention, a scanning system for a scanning probe microscope based on high-speed instantaneous force control is provided, comprising: a scanning device for a scanning probe microscope based on high-speed instantaneous force control as described in any of the third aspects of the present invention, used to scan a sample under the control of a set amplitude signal and generate a force signal; and

[0076] A mechanical property calculation module; the mechanical property calculation module is connected to the scanning module and is used to receive the force signal sent by the scanning module; and calculate a quantitative value based on the force signal, the quantitative value characterizing the surface features of the sample.

[0077] This invention provides a scanning method for a scanning probe microscope based on high-speed instantaneous force control, comprising: obtaining a true amplitude signal based on the force signal between the probe unit and the sample; generating a target force signal based on the true amplitude signal and a set amplitude signal, so that the probe unit scans the sample surface in a sample scanning mode under the control of the target force signal; since the target sample force signal used to control the probe unit to operate in the target sample scanning mode is generated based on the set amplitude signal and the true amplitude signal, the scanning mode of the probe unit is controlled by the set amplitude signal. Therefore, the technical solution provided by this invention realizes scanning imaging under the control of the set amplitude signal; by controlling the probe unit scanning with instantaneous force based on the peak force tapping mode, compared with scanning using other principles, the problem of limited scanning range is solved, ensuring the requirements of the product scanning range are met.

[0078] Furthermore, the surface of the sample is scanned using a scanning probe microscope based on high-speed instantaneous force control, forming a scanning motion and obtaining the force signal between the probe unit and the sample; a quantitative value is obtained based on the force signal; it can be seen that the quantitative value is directly obtained from the force signal, which solves the problem of low peak force tapping frequency and realizes high-frequency peak force tapping.

[0079] In summary, this invention achieves the goal of ensuring both high-frequency peak force tapping and the required probe scanning range. Attached Figure Description

[0080] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0081] Figure 1 This is a schematic flowchart of a scanning method for a scanning probe microscope based on high-speed instantaneous force control according to an embodiment of the present invention;

[0082] Figure 2 This is a flowchart illustrating a method for measuring mechanical properties based on a scanning probe microscope according to an embodiment of the present invention.

[0083] Figure 3 This is a schematic diagram of a scanning device for a scanning probe microscope based on high-speed instantaneous force control in one embodiment of the present invention;

[0084] Figure 4 This is a schematic diagram of a scanning module in one embodiment of the present invention;

[0085] Figure 5 This is a schematic diagram of the true amplitude calculation module in one embodiment of the present invention;

[0086] Figure 6 This is a schematic diagram of the true amplitude calculation module in another embodiment of the present invention;

[0087] Figure 7 This is a schematic diagram of a target force signal generation module in one embodiment of the present invention;

[0088] Figure 8 This is a schematic diagram showing the specific connection relationship of the scanning device of a scanning probe microscope based on high-speed instantaneous force control in one embodiment of the present invention;

[0089] Figure 9 This is a schematic diagram showing the specific connection relationship of the scanning device of a scanning probe microscope based on high-speed instantaneous force control in another embodiment of the present invention;

[0090] Figure 10 This is a schematic diagram of a scanning system for a scanning probe microscope based on high-speed instantaneous force control according to an embodiment of the present invention;

[0091] Figure 11 This is a schematic diagram of a scanning system for a scanning probe microscope based on high-speed instantaneous force control in a specific embodiment of the present invention;

[0092] Figure 12 This is a schematic diagram of a scanning system for a scanning probe microscope based on high-speed instantaneous force control in another specific embodiment of the present invention;

[0093] Figure 13 This is a schematic diagram of the interaction between the probe unit and the sample within a specific embodiment of the present invention;

[0094] Explanation of reference numerals in the attached figures:

[0095] 1-Probe cantilever beam;

[0096] 2-Probe tip;

[0097] 3-Laser;

[0098] 4- The laser emitted by the laser;

[0099] 5-Laser reflected from the back of the cantilever beam;

[0100] 6-Four-quadrant photodetector;

[0101] 7-Laser spot longitudinal deflection signal;

[0102] 8-Probe Holder;

[0103] 9-sample;

[0104] 10, 11, 12 - Comparators;

[0105] 13-Summation unit. Detailed Implementation

[0106] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0107] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0108] Currently, the fastest peak force tapping mode on the market is achieved by Bruker's Dimension Fast Scan, which scans at a peak force tapping frequency of 8kHz. However, its maximum scan area is only 35µm x 35µm. Furthermore, Dimension Fast Scan achieves its faster scanning speed through significant modifications to the previous generation of the scanner head. Also, the 8kHz peak force tapping frequency is only four times higher than the original 2kHz, resulting in a very limited speed improvement.

[0109] Fantner's group at the Swiss Federal Institute of Technology in Lausanne (EPFL) achieved a peak force tapping frequency of 100 kHz by replacing the traditional peak force tapping method with a photothermal effect-driven approach. However, the drawback is that the scanning range is very small, only 1.8 μm x 1.8 μm.

[0110] In view of this, after multiple experimental verifications, the inventors discovered that by separating the mechanical property calculation module and calculating the quantitative value solely using the force signal between the received sample and the probe, the problem of low peak force tapping frequency was solved, and high-frequency peak force tapping was achieved.

[0111] By introducing an instantaneous force setpoint to control probe scanning, combined with the peak force tapping mode in existing technology, the problem of limited scanning range is solved, ensuring the requirements for scanning range are met.

[0112] The high-speed instantaneous force control and nanoscale quantitative mechanical property measurement method of the present invention does not require any modification to the existing atomic force microscope system structure. It only changes the control method and can achieve a 100-fold increase in probe modulation frequency while maintaining the scanning range.

[0113] The technical solution of the present invention will be described in detail below with reference to specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0114] Please refer to Figure 1 According to an embodiment of the present invention, a scanning method for a scanning probe microscope based on high-speed instantaneous force control is provided, wherein the scanning probe microscope includes a probe unit, and the method includes the following steps:

[0115] S11: Acquire the force signal between the probe unit and the sample; the force signal characterizes the change of the force on the sample over time;

[0116] S12: Calculate the true amplitude signal based on the applied force signal; the true amplitude signal represents the amplitude of the applied force signal;

[0117] S13: Obtain the set amplitude signal;

[0118] S14: Obtain the first sine wave signal; and obtain the target force signal based on the actual amplitude signal, the set amplitude signal, and the first sine wave signal;

[0119] S15: Scan the surface of the sample in a target sample scanning mode according to the target force signal; the target sample scanning mode characterizes the working mode of scanning the sample surface under the instruction of the target force signal.

[0120] And repeat steps S11-S15 in a loop;

[0121] In step S11, the force signal between the probe unit and the sample is generated by scanning the scanning surface through the scanning module. The technical solution of the present invention introduces an instantaneous force setpoint signal and combines instantaneous force control with peak force tapping mode scanning to realize peak force tapping under instantaneous force control. Compared with the scanning mode driven by photothermal effect in the prior art, it solves the problem of limited scanning range and ensures the requirements of scanning range.

[0122] In one embodiment, obtaining the force signal between the probe unit and the sample in step S11 specifically includes:

[0123] Step S111: Obtain the target force signal;

[0124] Step S112: Scan the target sample according to the target force signal in the target scanning mode;

[0125] Step S113: During the scanning process of the target sample scanning mode, the scanning process is detected, and the force signal is generated.

[0126] In one embodiment, the step S12 of calculating the true amplitude signal based on the force signal specifically includes:

[0127] Step S121: Obtain the second sine signal, and generate a background signal based on the second sine signal under the triggering of the force signal;

[0128] Step S122: Obtain the average baseline signal based on the first force signal; the average baseline signal represents the average baseline of the first force signal;

[0129] Step S123: Obtain a second force signal based on the average baseline signal and the first force signal; the second force signal represents the second true force signal obtained by subtracting the average baseline signal from the first force signal;

[0130] Step S124: Obtain a third force signal based on the second force signal; the third force signal represents the third true force signal after the second force signal takes a positive value;

[0131] Step S125: Obtain the true amplitude signal based on the third force signal.

[0132] In another embodiment, the step S12 of calculating the true amplitude signal based on the force signal specifically includes:

[0133] Step S121: Obtain the third sine wave signal;

[0134] Step S122: Obtain a fourth force signal based on the third sine signal and the force signal, wherein the fourth force signal represents the signal obtained by mixing and multiplying the force signal and the third sine signal;

[0135] Step S123: Obtain the true amplitude signal based on the fourth force signal, wherein the true amplitude signal represents the amplitude signal of the force signal.

[0136] In one embodiment, step S14, obtaining the first sine wave signal and obtaining the target force signal based on the actual amplitude signal, the set amplitude signal, and the first sine wave signal, specifically includes:

[0137] Step S141: Obtain an error signal based on the true amplitude signal and the set amplitude signal; the error signal characterizes the error information between the true amplitude signal and the set amplitude signal;

[0138] Step S142: Obtain the control signal based on the error signal;

[0139] Step S143: Obtain the first sine wave signal;

[0140] Step S144: Obtain the target force signal based on the first sine signal and the control signal.

[0141] Secondly, according to an embodiment of the present invention, a method for measuring mechanical properties based on a scanning probe microscope is also provided, for measuring the mechanical properties of a sample surface. Please refer to [reference needed]. Figure 2 ;like Figure 2 As shown, the method for measuring mechanical properties based on a scanning probe microscope provided in this embodiment includes the following steps:

[0142] S21: The surface of the sample is scanned according to the scanning method of the scanning probe microscope based on high-speed instantaneous force control in the foregoing embodiment, forming a scanning motion and obtaining a force signal, wherein the force signal characterizes the characteristics of the force signal changing with time.

[0143] S22: A quantitative value is obtained based on the force signal; the quantitative value characterizes the surface features of the sample.

[0144] The mechanical characteristic calculation in the technical solution of this invention is not involved in the instantaneous force control and peak force tapping cycle described in the foregoing embodiments. Instead, quantitative values ​​are obtained directly from the force signal for sample surface imaging. Compared with existing technologies, high-frequency peak force tapping is achieved without changing the equipment, solving the problem of low probe unit modulation frequency. This achieves a 100-fold increase in probe modulation frequency.

[0145] In one embodiment, obtaining the quantitative value based on the sample scanning signal in step S22 specifically includes:

[0146] Step S221: Obtain the fifth force signal based on the sample scanning signal; the fifth force signal characterizes the variation of the force acting on the sample with the distance between the sample and the force-applying party;

[0147] Step S222: Determine several quantitative values ​​based on the contact mechanical model and the fifth force signal.

[0148] In one embodiment, the quantitative value includes: van der Waals force and / or capillary adhesion between the sample and the force-applying party.

[0149] Please refer to Figures 3-9 According to an embodiment of the present invention, a scanning device for a scanning probe microscope based on high-speed instantaneous force control is also provided, such as... Figure 3 As shown, the device includes:

[0150] The module comprises a scanning module 102, a true amplitude calculation module 103, a setpoint amplitude generation module 101, and a target force signal generation module 104.

[0151] One end of the scanning module 102 is connected to one end of the true amplitude calculation module 103, and the other end of the scanning module 102 is connected to one end of the target force signal generation module 104; the other end of the target force signal generation module 104 is connected to the other end of the true amplitude calculation module 103 and the instantaneous force setting amplitude generation module 101.

[0152] The scanning module 102 is used to scan the sample surface to generate a force signal and send the force signal to the true amplitude calculation module 103; the scanning module 102 performs scanning using a peak force tapping mode;

[0153] The true amplitude calculation module 103 is used to obtain the true amplitude signal based on the force signal and send the true amplitude signal to the target force signal generation module 104.

[0154] The set amplitude generation module 101 is used to generate a set amplitude signal and send the set amplitude signal to the target force signal generation module 104.

[0155] The target force signal generation module 104 is used to generate a target force signal using the real amplitude signal and the set amplitude signal, and send it to the scanning module 102; thereby controlling the scanning module 102 to perform scanning work in the target sample scanning mode according to the target force signal.

[0156] The scanning device of the scanning probe microscope based on high-speed instantaneous force control described in this invention utilizes the set amplitude generation module 101 to achieve instantaneous force control, and combines the real amplitude calculation module 103, the scanning module 102, the set amplitude generation module 101, and the target force generation module to realize peak force tapping scanning imaging under instantaneous force control; it solves the problem of limited scanning range in the prior art and meets the requirements for scanning range.

[0157] Combination Figure 3 , Figure 4 , Figure 8 As shown, in one embodiment, the scanning module 102 specifically includes:

[0158] The beam transmitting unit 1021, the signal detection unit 1022, the longitudinal piezoelectric driving unit 1026, the probe holding unit 1025, the probe cantilever beam unit 1024, and the probe unit 1023;

[0159] In this configuration, one end of the probe unit 1023 is mounted in the probe holding unit 1025, the probe cantilever beam unit 1024 is connected to the probe holding unit 1025 and supports the probe unit 1023, and the other end of the probe unit 1023 extends out of the probe cantilever beam unit 1024; one end of the longitudinal piezoelectric drive unit 1026 is connected to the probe holding unit 1025, and the other end of the longitudinal piezoelectric drive unit 1026 is connected to the target force signal generation module 104; the signal detection unit 1022 is connected to one end of the true amplitude calculation module 103.

[0160] Specifically, the probe holding unit 1025 is a probe holder 8, but it can also be other probe holding units 1025. This invention is not limited to these, and any implementation of the probe holding unit is within the protection scope of this invention.

[0161] The probe unit 1023 is used to periodically apply a certain force to the surface of the sample; and the probe unit 1023 is controlled by the longitudinal piezoelectric drive unit 1026; in one specific embodiment, the probe unit 1023 is a probe.

[0162] The longitudinal piezoelectric driving unit 1026 is used to drive the probe unit 1023 to work in the target sample scanning mode using the received target sample scanning signal. Specifically, the longitudinal piezoelectric driving unit 1026 is a longitudinal piezoelectric actuator, or it can be other longitudinal piezoelectric driving units 1026. The present invention is not limited to this, and any implementation of the longitudinal piezoelectric driving unit is within the protection scope of the present invention.

[0163] The beam transmitting unit 1021 is used to transmit a beam to the probe cantilever beam unit 1024; specifically, the beam transmitting unit 1021 is a laser 3, or it can be other beam transmitting units 1021. The present invention is not limited to this, and any implementation of the beam transmitting unit is within the protection scope of the present invention.

[0164] The probe cantilever beam unit 1024 is used to support the probe unit 1023 together with the probe holding unit 1025, and to reflect the received light beam transmitted by the light beam transmitting unit 1021 into the signal detection unit 1022; specifically, the probe cantilever beam unit 1024 is the probe cantilever beam 1, or it can be other probe cantilever beam units 1024. The present invention is not limited thereto, and any implementation of the probe cantilever unit is within the protection scope of the present invention.

[0165] The signal detection unit 1022 is used to generate the sample scanning signal based on the reflected beam detected on the probe cantilever beam unit, and send it to the true amplitude calculation module 103. Specifically, the signal detection unit 1022 is a four-quadrant photodetector 6, but it can also be other signal detection units 1022. This invention is not limited to these, and any implementation of the signal detection unit is within the protection scope of this invention, such as... Figure 4 , Figure 8 and Figure 9 As shown;

[0166] Combination Figure 3 , Figure 5 and Figure 8 As shown, in one embodiment, the true amplitude calculation module 103 specifically includes:

[0167] The system comprises a background generation unit 1031, a first comparison unit 1032, a baseline averaging and analysis unit 1033, a second comparison unit 1034, a signal positive conversion unit 1035, a second integration operation unit 1036, and a sine signal generation unit 1037.

[0168] One end of the background generation unit 1031 is connected to the signal detection unit 1022, and the other end of the background generation unit 1031 is connected to one end of the first comparison unit 1032 and one end of the sine wave signal generation unit 1037; one end of the first comparison unit 1032 is also connected to the signal detection unit 1022, and the other end of the first comparison unit 1032 is connected to one end of the baseline averaging unit 1033 and one end of the second comparison unit 1034; the other end of the baseline averaging unit 1033 is connected to one end of the second comparison unit 1034; the other end of the second comparison unit 1034 is connected to one end of the signal positive conversion unit 1035; the other end of the signal positive conversion unit 1035 is connected to one end of the second integration unit 1036; the other end of the second integration unit 1036 is connected to the target force signal generation module 104.

[0169] The sinusoidal signal generating unit 1037 is used to generate a first sinusoidal signal, a second sinusoidal signal, or a third sinusoidal signal, and send the second sinusoidal signal or the third sinusoidal signal to the real amplitude calculation module 103, and send the first sinusoidal signal to the target force signal generating module 104; specifically, the sinusoidal signal generating unit 1037 is a sinusoidal signal generator, or it can be other sinusoidal signal generating units 1037. The present invention is not limited thereto, and any implementation of the sinusoidal signal generating unit is within the protection scope of the present invention;

[0170] The background generation unit 1031 is used to trigger the background generation unit 1031 to generate a background signal according to the received second sine signal when the force signal is received, and send the background signal to the first comparison unit 1032; specifically, the background generation unit 1031 is a background generator, or it can be other types of background generation unit 1031. The present invention is not limited thereto, and any implementation of the background generation unit is within the protection scope of the present invention.

[0171] The first comparison unit 1032 is used to obtain a first force signal based on the received background signal and the force signal, and send the first force signal to the baseline averaging analysis unit 1033 and the second comparison unit 1034; specifically, the first comparison unit 1032 is a comparator 10, or it can be other types of first comparison unit 1032. The present invention is not limited thereto, and any implementation of the first comparison unit is within the protection scope of the present invention.

[0172] The baseline averaging analysis unit 1033 is used to generate an average baseline signal based on the received first force signal and send the average baseline signal to the second comparison unit 1034.

[0173] The second comparison unit 1034 is used to obtain a second force signal based on the received average baseline signal and the first force signal, and send the second force signal to the signal positive unit 1035; the second comparison unit 1034 is a comparator 11, or it can be other types of second comparison unit 1034. The present invention is not limited thereto, and any implementation of the second comparison unit is within the protection scope of the present invention.

[0174] The signal positive unit 1035 is used to obtain a third force signal based on the second force signal and send the third force signal to the second integration unit 1036;

[0175] The second integration unit 1036 is used to obtain the true amplitude signal based on the third force signal, and send the true amplitude signal to the target force signal generation module 104, such as... Figure 5 , Figure 8 As shown.

[0176] For another implementation of the true amplitude calculation module, please refer to... Figure 3 , Figure 6 and Figure 9 As shown, the true amplitude calculation module 103 specifically includes:

[0177] Phase-sensitive detection unit 1038 and low-pass filter unit 1039;

[0178] One end of the phase-sensitive detection unit 1038 is connected to the signal detection unit 1022, and the other end of the phase-sensitive detection unit 1038 is connected to one end of the low-pass filter unit 1039. The other end of the low-pass filter unit 1039 is connected to the target force signal generation module 104.

[0179] The phase-sensitive detection unit 1038 is used to obtain a fourth force signal based on the received force signal and the third sine signal, and send the fourth force signal to the low-pass filter unit 1039.

[0180] Low-pass filter unit 1039 is used to obtain the true amplitude signal based on the fourth force signal and send the true amplitude signal to the target force signal generation module 104, as shown in Figure 6. Figure 9 As shown.

[0181] Combination Figure 3 , Figure 7 , Figure 8 As shown, in one embodiment, the target force signal generation module 104 specifically includes:

[0182] The third comparison unit 1043, the control signal generation unit 1042, and the summation unit 1041;

[0183] One end of the third comparison unit 1043 is connected to the other end of the true amplitude calculation module 103 and the set amplitude calculation module; the other end of the third comparison unit 1043 is connected to one end of the control signal generation unit 1042; the other end of the control signal generation unit 1042 is connected to one end of the summing unit 1041; the other end of the summing unit 1041 is connected to the other end of the longitudinal electric drive unit and the other end of the sine signal generation unit 1037;

[0184] The third comparison unit 1043 is used to generate an error signal based on the true amplitude signal and the set amplitude signal, and send the error signal to the control signal generation unit 1042; the third comparison unit 1043 is a comparator 12, or it can be other types of third comparison unit 1043. The present invention is not limited thereto, and any implementation of the third comparison unit is within the protection scope of the present invention.

[0185] The control signal generation unit 1042 is used to generate a control signal based on the error signal and send the control signal to the summing unit 1041. Specifically, the control signal generation unit 1042 is a PI controller, or it can be other types of control signal generation unit 1042. This invention is not limited to this, and any implementation of the control signal generation unit is within the protection scope of this invention.

[0186] The summing unit 1041 is used to generate the target force signal based on the first sine signal and the control signal, and send the target force signal to the scanning module 102, such as... Figure 8 and Figure 9 As shown.

[0187] Please refer to Figure 10 According to an embodiment of the present invention, a scanning system for a scanning probe microscope based on high-speed instantaneous force control is also provided. The system includes: the scanning device for the scanning probe microscope based on high-speed instantaneous force control as described in the foregoing embodiment, and a mechanical characteristic calculation module 105; wherein:

[0188] The scanning device of the scanning probe microscope based on high-speed instantaneous force control is used to scan the sample under the control of instantaneous force point and generate an action force signal; the mechanical property calculation module 105 is connected to the scanning module 102 and is used to receive the action force signal sent by the scanning module 102; and calculate a quantitative value based on the action force signal, the quantitative value characterizing the surface features of the sample.

[0189] The technical solution of this invention, based on peak force tapping imaging under instantaneous force control, separates the mechanical characteristic calculation module 105 from the loop formed by the set amplitude generation module, the true amplitude calculation module 103, and the target force signal generation module 104. It directly generates quantitative values ​​based on the force signal generated by the scanning module 102, which are then used for imaging. Compared with the prior art, this solution not only solves the problem of limited scanning range in the prior art but also solves the problem of low scanning frequency. It simultaneously improves both the requirements for scanning range and scanning frequency.

[0190] In one embodiment, the mechanical property calculation module 105 is specifically connected to the signal detection unit 1022 in the scanning module 102, and is used to receive the force signal sent by the signal detection unit 1022; and calculate a quantitative value based on the force signal, the quantitative value characterizing the surface features of the sample, such as... Figure 10 As shown.

[0191] In one specific embodiment, the scanning probe microscope is an atomic force microscope, but it is not limited to the atomic force microscope. It can also be a transverse force microscope, a scanning tunneling microscope, or an electrostatic force microscope. It should be understood that the scanning probe microscope described in this invention is not limited to these. As long as it meets the requirements of this invention, it is within the protection scope of this invention.

[0192] The following description uses an atomic force microscope as an example, combined with a specific embodiment of the invention, to further illustrate the invention in detail; please refer to... Figures 11-13 .

[0193] like Figure 11As shown, the probe is mounted in the probe holder 8 and has a probe cantilever beam 1 supporting the probe tip 2. In this case, the probe tip-sample separation is modulated by a longitudinal piezoelectric driver. The laser 3 emits laser light onto the probe cantilever beam 1, and the laser light reflected from the probe cantilever beam 1 is captured by a four-quadrant photodetector 6.

[0194] During operation, the four-quadrant photodetector 6 generates a laser spot longitudinal deflection signal 7 based on the reflected light of the laser 4 emitted by the laser 3, i.e., the laser 5 reflected from the back of the cantilever beam. The laser spot longitudinal deflection signal 7 is a force signal.

[0195] The laser spot longitudinal deflection signal 7 is then transmitted to the background generator, which generates a background signal, which refers to the periodic waveform of the background signal when the needle tip does not interact with the sample.

[0196] Comparator 10 processes force signal 7 by subtracting background signal to generate first force signal, which represents the signal of probe tip-sample interaction force independent of parasitic background.

[0197] The first force signal is transmitted to the baseline averaging unit to determine the baseline and generate an average baseline signal.

[0198] Comparator 11 processes the first force signal by subtracting the average baseline signal to generate a second force signal, which represents the tip-sample interaction force without cantilever DC drift.

[0199] The signal is further transferred to the signal positive unit to obtain the third force signal. The third force signal indicates that the longitudinal deflection signal 7 of the laser spot only leaves a positive deflection signal and is transmitted to the integrator. The true amplitude signal is obtained through integration. The true amplitude signal refers to the amplitude of the deflection signal after positive deflection and is transmitted to the comparator 12 in DC form.

[0200] The set amplitude generation module 101 generates a set amplitude signal and transmits it to the comparator 12. The comparator 12 compares the set amplitude signal with the actual amplitude signal, generates an error signal, and transmits the error signal to the PI controller, which in turn generates a control signal. The control signal is then transmitted to the summing unit 13, which combines it with a first sine signal generated by the sine wave generator to generate a target force signal. The summing unit 13 then applies the target force signal to the longitudinal piezoelectric actuator, which drives the probe holder 8 to maintain the interaction between the probe tip 2 and the sample 9 in a substantially stable state.

[0201] While the control loop is operating, the laser spot longitudinal deflection signal 7 is transmitted to the mechanical property calculation module for semi-online calculation to obtain the nanoscale quantitative mechanical properties of sample 9. Specifically, the laser spot longitudinal deflection signal 7 is converted into a fifth force signal, which refers to the curve of the interaction force between the probe tip and the sample. The magnitude is determined using, for example, the Oliver-Pharr model, DMT model, Snedden model, Hertz model, or other contact mechanics models, using the upper part of the ramp; the quantitative values ​​include van der Waals attraction and capillary adhesion force occurring when the tip leaves the sample, etc.

[0202] like Figure 12 As shown, when the true amplitude calculation module consists of a phase-sensitive detector, a low-pass filter, and a sine wave generator, the longitudinal deflection signal 7 of the laser spot generated by the four-quadrant photodetector 6 is sent to the phase-sensitive detector. The phase-sensitive detector generates a fourth force signal, which is sent to the low-frequency filter. The low-frequency filter generates the true amplitude signal and sends it to the comparator 12. Other processes are the same as in the above embodiments and will not be described again here.

[0203] The other end (output) of the integrator or low-frequency filter can also be connected to an instantaneous force point analysis unit; the instantaneous force point analysis unit is used to analyze the real amplitude signal output by the integrator (or low-frequency filter) to obtain an instantaneous force point analysis signal; the instantaneous force point analysis signal is used for quantitative analysis; Figure 11 and Figure 12 The arrows extending from the instantaneous force point analysis unit indicate the instantaneous force point analysis signal output by the instantaneous force point analysis unit.

[0204] The detected signal of the interaction between probe tip 2 and sample 9 surface is as follows: Figure 13 As shown, the upper part is the curve of the distance between the probe tip 2 and the sample 9 changing with time, and the lower part is the curve of the longitudinal force changing with time. The longitudinal force includes the van der Waals force, capillary adhesion force and contact force between the probe tip 2 and the surface of the sample 9.

[0205] The interaction between probe tip 2 and sample 9 comprises three intervals, marked by vertical lines p1 to p5 that represent the timestamps of these three interaction intervals. p1 to p2 represents the van der Waals force interval, p2 to p4 represents the contact force interval, and p4 to p5 represents the capillary adhesive force interval. The synchronous signal is the timestamp signal from p1 to p5.

[0206] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A scanning method for a scanning probe microscope based on high-speed instantaneous force control, wherein, The scanning probe microscope includes a probe unit, characterized by comprising the following steps: The force signal between the probe unit and the sample is acquired; the force signal characterizes the change of the force on the sample over time. The true amplitude signal is calculated based on the applied force signal; the true amplitude signal represents the amplitude of the applied force signal. Obtain the set amplitude signal; Obtain the first sine wave signal; and obtain the target force signal based on the actual amplitude signal, the set amplitude signal, and the first sine wave signal; The surface of the sample is scanned in a target sample scanning mode based on the target force signal; the target sample scanning mode characterizes the working mode of scanning the sample surface under the instruction of the target force signal. The specific steps for calculating the true amplitude signal based on the force signal include: Obtain the third sine wave signal; A fourth force signal is obtained based on the third sinusoidal signal and the force signal, and the fourth force signal represents the signal obtained by mixing and multiplying the force signal and the third sinusoidal signal. The true amplitude signal is obtained based on the fourth force signal, and the true amplitude signal represents the amplitude signal of the force signal. Obtain the first sine wave signal; obtain the target force signal based on the actual amplitude signal, the set amplitude signal, and the first sine wave signal. The specific steps are as follows: An error signal is obtained based on the true amplitude signal and the set amplitude signal; the error signal characterizes the error information between the true amplitude signal and the set amplitude signal. The control signal is obtained based on the error signal; Obtain the first sine wave signal; The target force signal is obtained based on the first sine signal and the control signal.

2. The scanning method of the scanning probe microscope based on high-speed instantaneous force control according to claim 1, characterized in that, The specific steps for obtaining the force signal between the probe unit and the sample include: Obtain the target force signal; The target sample is scanned according to the target force signal in the scanning mode. During the scanning process of the target sample scanning mode, the scanning process is detected, and the force signal is generated.

3. A method for measuring mechanical properties based on scanning probe microscopy, used to measure the mechanical properties of a sample surface, characterized in that, The method includes the following steps: The scanning method of the scanning probe microscope based on high-speed instantaneous force control according to claim 1 scans the surface of the sample, forms a scanning motion, and obtains a force signal, wherein the force signal characterizes the characteristics of the force signal changing with time. A quantitative value is obtained based on the force signal; the quantitative value characterizes the surface features of the sample.

4. The method for measuring mechanical properties based on a scanning probe microscope according to claim 3, characterized in that, The quantitative value is obtained based on the sample scanning signal. The specific steps include: The fifth force signal is obtained based on the sample scanning signal; the fifth force signal characterizes the variation of the force acting on the sample with the distance between the sample and the force-applying party; Several quantitative values ​​are determined based on the contact machinery model and the fifth force signal.

5. The method for measuring mechanical properties based on a scanning probe microscope according to claim 4 is characterized in that, The quantitative values ​​include: van der Waals forces and / or capillary adhesion between the sample and the force-applying party.

6. A scanning device for a scanning probe microscope based on high-speed instantaneous force control, the device being used to implement the scanning method of a scanning probe microscope based on high-speed instantaneous force control as described in any one of claims 1-5, characterized in that, include: The module includes a scanning module, a true amplitude calculation module, a set amplitude generation module, and a target force signal generation module. One end of the scanning module is connected to one end of the true amplitude calculation module, and the other end of the scanning module is connected to one end of the target force signal generation module; the other end of the target force signal generation module is connected to the other end of the true amplitude calculation module and the set amplitude generation module. The scanning module is used to scan the sample surface to generate a force signal and send the force signal to the real amplitude calculation module. The true amplitude calculation module is used to obtain the true amplitude signal based on the force signal and send the true amplitude signal to the target force signal generation module; The set amplitude generation module is used to generate a set amplitude signal and send the set amplitude signal to the target force signal generation module; The target force signal generation module is used to generate a target force signal using the real amplitude signal and the set amplitude signal, and send it to the scanning module; thereby controlling the scanning module to perform scanning work in the target sample scanning mode according to the target force signal. The scanning module specifically includes: The beam transmitting unit, signal detection unit, longitudinal piezoelectric driving unit, probe holding unit, probe cantilever beam unit, and probe unit are all included. In this configuration, one end of the probe unit is mounted in the probe holding unit, the probe cantilever beam unit is connected to the probe holding unit and supports the probe unit, and the other end of the probe unit extends out of the probe cantilever beam unit; one end of the longitudinal piezoelectric drive unit is connected to the probe holding unit, and the other end of the longitudinal piezoelectric drive unit is connected to the target force signal generation module; the signal detection unit is connected to one end of the true amplitude calculation module. The probe unit is used to periodically apply a certain force to the surface of the sample; and the probe unit is controlled by the longitudinal piezoelectric drive unit. The longitudinal piezoelectric drive unit is used to drive the probe unit to operate in the target sample scanning mode using the received target sample scanning signal; The beam transmitting unit is used to transmit a beam to the probe cantilever beam unit; The probe cantilever beam unit is used to support the probe unit together with the probe holding unit, and to reflect the received beam transmitted by the beam transmitting unit into the signal detection unit; The signal detection unit is used to generate the sample scanning signal based on the reflected beam detected on the probe cantilever beam unit, and send it to the mechanical property calculation module and the true amplitude calculation module. The actual amplitude calculation module specifically includes: Phase-sensitive detection unit and low-pass filter unit; One end of the phase-sensitive detection unit is connected to the signal detection unit, the other end of the phase-sensitive detection unit is connected to one end of the low-pass filter unit, and the other end of the low-pass filter unit is connected to the target force signal generation module. The phase-sensitive detection unit is used to obtain a fourth force signal based on the received force signal and the third sine signal, and send the fourth force signal to the low-pass filter unit. A low-pass filter unit is used to obtain the true amplitude signal based on the fourth force signal and send the true amplitude signal to the target force signal generation module; The target force signal generation module specifically includes: The third comparison unit, the control signal generation unit, and the summation unit; One end of the third comparison unit is connected to the other end of the true amplitude calculation module and the set amplitude calculation module; the other end of the third comparison unit is connected to one end of the control signal generation unit; the other end of the control signal generation unit is connected to one end of the summing unit; the other end of the summing unit is connected to the other end of the longitudinal electric drive unit and the other end of the sine signal generation unit. The third comparison unit is used to generate an error signal based on the true amplitude signal and the set amplitude signal, and send the error signal to the control signal generation unit; The control signal generation unit is used to generate a control signal based on the error signal and send the control signal to the summing unit; The summing unit is used to generate the target force signal based on the first sine signal and the control signal, and send the target force signal to the scanning module.

7. A scanning system for a scanning probe microscope based on high-speed instantaneous force control, characterized in that, include: The scanning device of the scanning probe microscope based on high-speed instantaneous force control as described in claim 6 is used to scan the sample under the control of a set amplitude signal and generate a force signal. as well as A mechanical property calculation module; the mechanical property calculation module is connected to the scanning module and is used to receive the force signal sent by the scanning module; and calculate a quantitative value based on the force signal, the quantitative value characterizing the surface features of the sample.

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