Scanning Probe Microscope System

Abstract

The present application relates to a scanning probe microscope system, which includes a plurality of probe holders, a main body probe head, a main body base, and a measurement and control device. Each probe holder is configured to mount a sensing probe. The main body probe head includes a front-end circuit and a positioning guide groove. The positioning guide groove is configured to detachably mount a plurality of probe holders. The probe holder is electrically connected to the front-end circuit. The main body base is configured to support the main body probe head and is signal-connected to the sensing probe. The measurement and control device is signal-connected to the main body base. During use, one of the probe holders is selected and mounted in the positioning guide groove of the main body probe head, and the measurement and control device realizes signal interaction with the corresponding sensing probe through the main body base, so that the scanning probe microscope system can realize the function of arbitrary measurement and imaging, that is, it can be used immediately, and the compatible use of a variety of sensing probes is realized.

Description

Technical Field

[0001] The present application relates to the technical field of microscopes, and particularly to a scanning probe microscope system. Background Art

[0002] A scanning probe microscope (SPM) uses a sharp probe to scan the surface of a sample to obtain some properties of the sample surface. Different SPMs usually use different sensing probes, and their tip characteristics and corresponding tip-sample interactions are different. The scanning tunneling microscope (STM) is the first type of instrument invented in SPM. STM is based on the principle of electron tunneling effect and uses a conductive metal tip to detect the tunneling current, thereby detecting the local electron density of the sample for measurement and imaging.

[0003] The atomic force microscope (AFM) is another important type of instrument in SPM and is currently the most widely used. AFM can image the topography of a sample. AFM can also perform high-resolution measurement and imaging of the local surface potential, charge, carrier density, conductivity, etc. of the sample. Currently, in different environments, different sensing probes need to be used, and at this time, different host probes and measurement and control systems need to be equipped, and even a complete set of dedicated instruments need to be designed and equipped, resulting in great technical difficulty, high cost, and time-consuming and laborious implementation. Summary of the Invention

[0004] Based on this, in view of the above technical problems, the present application provides a scanning probe microscope system.

[0005] The present application provides a scanning probe microscope system, including:

[0006] A plurality of probe holders, each probe holder being configured to mount a sensing probe;

[0007] A host probe, including a front-end circuit and a positioning guide groove, the positioning guide groove being configured to detachably mount the plurality of probe holders, and the probe holder being electrically connected to the front-end circuit;

[0008] A host base, configured to support the host probe and signal-connected to the sensing probe; and

[0009] A measurement and control device, signal-connected to the host base.

[0010] In one embodiment, when any one of the plurality of probe holders is mounted on the positioning guide groove, the position of the tip of the sensing probe thereon relative to the positioning guide groove remains unchanged.

[0011] In one embodiment, the positioning guide groove is configured to install the plurality of probe holders by insertion.

[0012] In one embodiment, the sensing probe includes a self-sensing atomic force probe, a laser detection atomic force probe, and a scanning tunneling microscope probe.

[0013] In one embodiment, the host probe further includes:

[0014] A laser diode that emits laser light irradiated at a set position of the laser detection atomic force probe; and

[0015] A position detector, and the laser light reflected from the set position is irradiated at the center position of the position detector.

[0016] In one embodiment, the preamplifier circuit includes:

[0017] An identification circuit electrically connected to the probe holder.

[0018] In one embodiment, the preamplifier circuit further includes:

[0019] A preamplifier drive circuit, the first end of the preamplifier drive circuit is connected to the sensing probe; and

[0020] A self-excitation circuit connected to the preamplifier drive circuit to form a negative feedback loop.

[0021] In one embodiment, the preamplifier drive circuit includes:

[0022] A signal attenuation circuit, the first end of the signal attenuation circuit is connected to the sensing probe;

[0023] A capacitance compensation circuit, the first end of the capacitance compensation circuit is connected to the second end of the signal attenuation circuit; and

[0024] A current-voltage conversion circuit, the first end of the current-voltage conversion circuit is connected to the second end of the capacitance compensation circuit.

[0025] In one embodiment, the self-excitation circuit includes:

[0026] A programmable gain amplifier circuit, the first end of the programmable gain amplifier circuit is connected to the second end of the current-voltage conversion circuit;

[0027] A root mean square circuit, the first end of the root mean square circuit is connected to the second end of the programmable gain amplifier circuit;

[0028] A subtraction circuit, the first end of the subtraction circuit is connected to the second end of the root mean square circuit;

[0029] A multiplier, the first end of the multiplier is connected to the second end of the subtraction circuit, and the second end of the multiplier is connected to the second end of the programmable gain amplifier circuit;

[0030] A phase shift circuit, the first end of the phase shift circuit is connected to the third end of the multiplier; and

[0031] An analog switch, the first end of the analog switch is connected to the second end of the phase shift circuit, and the second end of the analog switch is connected to the third end of the signal attenuation circuit.

[0032] In one embodiment, the pre-driver circuit includes a plurality of operational amplifiers, the voltage amplitude change of the plurality of operational amplifiers within 1 microsecond is ±0.01%, and the high slew rate is greater than or equal to 16V / s.

[0033] The above scanning probe microscope system includes a plurality of probe holders, a main probe head, a main probe base, and a measurement and control device. Each probe holder is configured to mount a sensing probe. The main probe head includes a pre-circuit and a positioning slot. The positioning slot is configured to detachably mount the plurality of probe holders. The probe holder is electrically connected to the pre-circuit. The main probe base is configured to support the main probe head and is signal-connected to the sensing probe. The measurement and control device is signal-connected to the main probe base. In this application, for each type of sensing probe, a probe holder is designed and configured. All probe holders can be detachably mounted in the positioning slot of the main probe head. And all probe holders can be electrically connected to the pre-circuit. During use, one of the probe holders is selected and mounted in the positioning slot of the main probe head, and the measurement and control device realizes signal interaction with the corresponding sensing probe through the main probe base, so that the scanning probe microscope system can realize any measurement and imaging function, that is, it can be used immediately, realizing the compatible use of multiple sensing probes. Description of the Drawings

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0035] Figure 1 Schematic structural diagram of a scanning probe microscope system provided by an embodiment of the present application;

[0036] Figure 2 Schematic structural diagram of a scanning probe microscope system provided by another embodiment of the present application;

[0037] Figure 3Schematic structural diagram of a scanning probe microscope system provided by another embodiment of the present application;

[0038] Figure 4 Schematic connection diagram of a front-end circuit structure provided by an embodiment of the present application;

[0039] Figure 5 Schematic connection diagram of a front-end drive circuit structure provided by an embodiment of the present application.

[0040] Description of reference numerals of main components

[0041] 100, scanning probe microscope system; 11, probe holder; 12, sensing probe; 20, host probe; 21, front-end circuit; 22 front-end drive circuit; 23 self-excitation circuit; 221, signal attenuation circuit; 222 capacitance compensation circuit; 223 current-voltage conversion circuit; 231, programmable gain amplifier circuit; 232, root mean square circuit; 233, subtraction circuit; 234 multiplier; 235, phase shift circuit; 236, analog switch; 24, laser diode; 25 position detector; 30, host base; 31, piezoelectric scanner; 32 sample to be scanned; 33, probe height coarse adjustment assembly; 40, measurement and control device; 41, main controller; 42, computer. Detailed implementation manners

[0042] To make the above objects, features, and advantages of the present application more obvious and understandable, the following describes the detailed implementation manners of the present application with reference to the accompanying drawings. Many specific details are set forth in the following description to fully understand the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present application. Therefore, the present application is not limited by the specific implementations disclosed below.

[0043] It can be understood that the terms "first", "second", etc. used in the present application can be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish a first element from another element. For example, without departing from the scope of the present application, the first acquisition module can be called the second acquisition module, and similarly, the second acquisition module can be called the first acquisition module. Both the first acquisition module and the second acquisition module are acquisition modules, but they are not the same acquisition module.

[0044] It should be noted that when an element is referred to as being "disposed on" another element, it can be directly on the other element or there may also be an intermediate element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time.

[0045] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. The terms used in the description of this application herein are for the purpose of describing specific embodiments only and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0046] This application provides a scanning probe microscope system 100. The scanning probe microscope system 100 includes a plurality of probe holders 11, a main body probe 20, a main body base 30, and a measurement and control device 40.

[0047] Each probe holder 11 is configured to mount a sensing probe 12. The main body probe 20 includes a front-end circuit 21 and a positioning guide groove. The positioning guide groove is configured to detachably mount the plurality of probe holders 11, and the probe holders 11 are electrically connected to the front-end circuit 21. The main body base 30 is configured to support the main body probe 20 and is signal-connected to the sensing probe 12. The measurement and control device 40 is signal-connected to the main body base 30. The structure of the measurement and control device 40 is not specifically limited as long as it can be signal-connected to the main body base 30 to achieve signal interaction with the corresponding sensing probe 12 so that the scanning probe microscope system 100 can implement any measurement and imaging function as needed.

[0048] In an implementable manner, the measurement and control device 40 includes a main controller 41 and a computer 42. The main controller 41 in the scanning probe microscope system 100 mainly includes: a coarse adjustment control circuit, a scanning control circuit, a feedback and imaging circuit, etc. The function of the feedback control circuit is to receive the signal detected by the sensing probe 12 (such as the force signal in AFM), compare it with the set reference signal (such as setting the force magnitude to 1 nanonewton), and then output an error signal. According to this error signal, the voltage value V of the piezoelectric scanner 31 in the vertical direction (Z direction) is adjusted z , so as to control the height of the sample 32 to be scanned so that the effective distance between the probe and the sample 32 to be scanned, or the deformation amount of the probe, or the interaction force remains constant. In this way, the voltage value V z can be used as the local height, i.e., the topography, of the sample 32 to be scanned at different positions. By scanning the position of the probe tip on the sample 32 to be scanned through the scanning control circuit, a topography image can be obtained.

[0049] For each type of sensing probe 12 in this application, a probe holder 11 is designed and configured. All the probe holders 11 can be detachably installed in the positioning guide grooves of the main probe head 20. Moreover, all the probe holders 11 can be electrically connected to the front-end circuit 21. During use, one of the probe holders 11 is selected and installed in the positioning guide groove of the main probe head 20, and the measurement and control device 40 realizes signal interaction with the corresponding sensing probe 12 through the main probe base 30, so that the scanning probe microscope system 100 can realize any measurement and imaging function on a selected-and-used basis, achieving the compatible use of multiple sensing probes 12.

[0050] In one embodiment, when any one of the multiple probe holders 11 is installed in the positioning guide groove, the position of the tip of the sensing probe 12 thereon relative to the positioning guide groove remains unchanged. That is, a main probe head 20 can be configured with multiple probe holders 11, and when different probe holders 11 are installed with different sensing probes 12, the mechanical positions of the probe tips are basically unchanged (the same applies to the main probe base 30). This makes the position of the probe tip relative to the center of the sample 32 to be scanned basically unchanged during each measurement, facilitating in-situ and comparative measurements.

[0051] In one embodiment, the positioning guide grooves are configured to install the multiple probe holders 11 by insertion. For each type of sensing probe 12, a probe holder 11 assembly is designed and configured to meet the installation requirements of its mechanical structure. The external installation dimensions of all the probe holders 11 are compatible, so that all the probe holders 11 can be tightly installed in the positioning guide grooves of the main probe head 20 by insertion.

[0052] The electrical interfaces between the probe holder 11 and the main probe head 20 are compatible, and the measurement and control device 40 has the measurement functions required for all the sensing probes 12 and can be used on a selected-and-used basis. That is, a unified electrical interface is adopted between the probe holder 11 and the main probe head 20, which is compatible with various sensing probes 12, can realize the automatic identification of the probe holder 11 type, and can also configure or modify the measurement functions or parameters through the user measurement and control software (computer 42, mobile phone, etc.). Any measurement and imaging function of all the sensing probes 12 can be realized on a selected-and-used basis.

[0053] In one embodiment, the sensing probe 12 includes a self-sensing atomic force probe (hereinafter referred to as a self-sensing AFM probe), a laser detection atomic force probe (hereinafter referred to as a laser detection AFM probe), and a scanning tunneling microscope probe. As Figures 1-3 shown, they are respectively the structural diagrams of the scanning probe microscope system 100 using a tuning fork type self-sensing AFM probe, the structural diagram of the scanning probe microscope system 100 using a laser detection AFM probe, and the structural diagram of the scanning probe microscope system 100 using a scanning tunneling microscope probe.

[0054] In this embodiment, a total of three types of probe holders 11 are designed: the probe holder 11 for self-sensing AFM probes, the probe holder 11 for laser-detection AFM probes, and the probe holder 11 for scanning tunneling microscope probes. Among them, the probe holder 11 for self-sensing AFM probes has two types (slightly different in size), which are respectively used to install the self-made balanced tuning fork type self-sensing probe and the A-probe self-sensing probe, and can realize the measurement and topography imaging functions based on frequency modulation and the self-excitation of the tuning fork probe. The probe holder 11 for laser-detection AFM probes can install two types of probes, and can respectively realize the measurement and topography imaging functions in the contact mode and the tapping mode based on amplitude modulation. The probe holder 11 of the scanning tunneling microscope is used to install the tungsten (W) or platinum / iridium (PtIr) metal filaments commonly used in the scanning tunneling microscope, and the sharp tips are usually formed by electrochemical etching, and can realize the measurement and imaging functions of the scanning tunneling microscope.

[0055] The main probe 20 in the scanning probe microscope system 100 is installed above the main base 30 and is supported by the probe height coarse adjustment component 33 (stepping motor and lifting screw) in the main base 30. In this example, there are 3 sets of height coarse adjustment components including the lifting screw. Under the control of the main controller 41 and the computer 42, the height coarse adjustment component can drive the screw to lift, thereby driving the lifting of the main probe 20, so that the distance between the probe tip and the sample 32 to be scanned changes. When the scanning probe microscope performs measurement and imaging, the tip and the sample 32 to be scanned are usually in a contact state (repulsive interaction with each other) or the distance is very small (dominated by attractive interaction, or long-range forces such as electrostatic force and magnetic force, and the distance is in the range of a few nanometers to 100 nanometers), and it is necessary to measure the magnitude of this interaction force or to realize measurement or imaging through this interaction force.

[0056] The main probe 20 in the scanning probe microscope system 100 can be configured with a variety of probe holders 11, which are respectively used for the installation of self-sensing AFM probes, laser-detection AFM probes, scanning tunneling microscope probes, etc., but only one of the probe holders 11 can be inserted at the same time. The front-end circuit 21 includes all the circuits required for the signal processing of various types of probes. In one of the embodiments, the front-end circuit 21 includes an identification circuit. The identification circuit is electrically connected to the probe holder 11. After automatically identifying the type of the probe holder 11 through the identification circuit, these circuits can be automatically selected for use, or the use of these circuits can be selected through the main controller 41 or the user software (computer 42).

[0057] The main base 30 in the scanning probe microscope system 100 includes a piezoelectric scanner 31. The sample 32 to be scanned and measured is first mounted on the sample stage to be scanned, and the sample stage is mounted on the piezoelectric scanner 31. The function of the piezoelectric scanner 31 is to drive the sample 32 to be scanned and measured to move in the X, Y, and Z directions, so as to realize the scanning of the sample 32 to be scanned and the precise motion control of the height. The maximum range of motion control is usually 1 micron - 100 microns, and the accuracy or resolution can reach about 0.01 nanometers. In the main base 30, a second position adjustment device for the piezoelectric scanner 31 and the sample 32 to be scanned and measured in the horizontal plane is usually provided, and its adjustment range is usually about + / - 10 millimeters.

[0058] The probe holder 11 electrical signal interface (compatible with various probes) is shown in Table 1. In the main probe 20 of the host, the probe holder 11 and the preamplifier circuit 21 are connected through the signals between the M1 - probe holder 11 and the preamplifier circuit 21, and there are a total of 8 signals. Among them, pin 2 (DI2 - ISO) and pin 3 (DI3 - ISO) are used for the automatic identification of the type of the probe holder 11. When the probe holder 11 is not installed, these two input signals are floating, and the signals are both high level (11).

[0059] Table 1 Signal interface between the probe holder 11 components and the preamplifier circuit 21 (compatible with various probes)

[0060]

[0061] For different probe holders 11, the specific identification method and working process are as follows:

[0062] 1. Probe holder 11 for self - sensing AFM probes:

[0063] On the probe holder 11 for self - sensing AFM probes, these two signals are directly connected to the signal ground (pin 5, analog signal ground). Therefore, after the probe holder 11 for self - sensing AFM probes is installed, these two input signals are short - circuited to the ground, and the signals are both low level (00). The main controller 41 and the computer 42 of the scanning probe microscope can then determine that the probe holder 11 for tuning - fork type self - sensing probes is being used at this time. At this time, pin 4 (TF Tapping, probe vibration excitation of TF) and pin 7 (TF Sensor, TF sensing signal output) are connected to the probe signal preamplifier circuit 21 for the measurement or imaging of tuning - fork type self - sensing probes; while pins 1, 6, and 8 do not function.

[0064] The probe holder 11 of the self-sensing AFM probe has two types (slightly different in size), which are respectively used to install the self-made balanced tuning fork type self-sensing probe and the A-probe self-sensing probe, and can realize the measurement and topography imaging functions based on frequency modulation and self-excitation of the tuning fork probe. The physical sizes of these two different self-sensing probes are slightly different. Therefore, the probe holder 11 is also slightly different. The circuit parameters of driving and detecting these two different self-sensing probes are also slightly different. Therefore, the settings of their measurement and control parameters are also slightly different; the settings can be manually completed by the user through the measurement and control software on the main controller 41 or the computer 42.

[0065] 2. The probe holder 11 of the laser detection AFM probe

[0066] On the probe holder 11 of the laser detection AFM probe, the pin 2 (DI2-ISO) is directly connected to the signal ground (pin 5, analog signal ground), and the pin 3 (DI3-ISO) is left floating (not connected). After installing the probe holder 11 of the laser detection AFM probe, these two input signals are respectively low level and high level (01), and the controller of the scanning probe microscope and the measurement and control software in the computer 42 can judge that the probe holder 11 of the laser detection AFM probe is used at this time. As Figure 2 shown, the preamplifier circuit 21 in the main probe 20 outputs a signal to drive the laser diode 24 to emit a laser signal, which irradiates the back of the microcantilever probe and then is emitted to the position detector 25 to detect the deformation of the microcantilever probe, so as to detect the interaction force between the probe and the sample 32 to be scanned. In this way, the measurement and imaging functions of the contact mode AFM can be realized.

[0067] If a tapping mode AFM probe is installed, the probe vibration excitation provided by the main controller 41 can be output to the probe through the pin 1 (AFM Tapping, probe vibration excitation of AFM), so as to realize the measurement and imaging functions of the tapping mode AFM. The circuit parameters of driving and detecting these two different laser detection type AFMs in the contact mode and the tapping mode are slightly different. Therefore, the settings of their measurement and control parameters are also slightly different; the settings can be manually completed by the user through the measurement and control software on the main controller 41 or the computer 42.

[0068] In addition, if the installed tip is a conductive AFM probe, the probe bias signal can be output to the conductive tip of the probe through the pin 6 (TipBias, probe bias), so as to realize the measurement and imaging functions based on conductive AFM such as conductive atomic force microscope, electrostatic force microscope or Kelvin probe force microscope.

[0069] 3. The probe holder 11 of the scanning tunneling microscope

[0070] On the probe holder 11 of the scanning tunneling microscope, pin 2 (DI2-ISO) is suspended (not connected), and pin 3 (DI3-ISO) is directly connected to the signal ground (pin 5, analog signal ground). Therefore, these two input signals are at high level and low level (10) respectively. The controller of the scanning probe microscope and the measurement and control software in the computer 42 can then determine that the probe holder 11 of the scanning tunneling microscope is being used at this time. As Figure 3 shown, the tunneling current signal from the tip is connected to the probe signal preamplifier circuit 21 in the host probe 20 through pin 4 (STM Sensor, tunneling current), thus completing the measurement and imaging functions of the scanning tunneling microscope.

[0071] In one embodiment, the host probe 20 further includes a laser diode 24 and a position detector 25.

[0072] The laser emitted by the laser diode 24 irradiates at the set position of the laser detection atomic force probe. The laser reflected from the set position irradiates at the central position of the position detector 25.

[0073] It should be noted that components such as the laser diode 24 and the position detector 25 in the host probe 20 are only required when using the probe holder 11 of the laser detection type AFM probe, but these two components are always installed in the host probe 20 for standby. The laser diode 24 can be a semiconductor laser diode. The position detector 25 is used to detect the position of the laser spot. Optionally, in the host probe 20, first position adjustment devices for the laser diode 24 and the position detector 25 are respectively provided in the horizontal plane, and their adjustment ranges are generally about + / -5 mm.

[0074] In order to keep the amplitude of the quartz tuning fork constant at its resonant frequency during self-oscillation. This requires the self-oscillation module and the pre-driver module in the probe measurement and control circuit to form an electrical circuit with specific functions. In one embodiment, the preamplifier circuit 21 further includes a pre-driver circuit 22, a self-excitation circuit 23, and a frequency measurement module (not shown in the figure). The first end of the pre-driver circuit 22 is connected to the sensing probe 12. The self-excitation circuit 23 is connected to the pre-driver circuit 22 to form a negative feedback loop.

[0075] The pre-driver circuit 22 functions to input the excitation signal and output the response signal, and this part is directly connected to the sensing probe 12. The error in this part will have a very large impact on the signal quality. Please refer to Figure 4In one embodiment, the pre-drive circuit 22 includes a signal attenuation circuit 221, a capacitance compensation circuit 222 and a current-voltage conversion circuit 223. The first end of the signal attenuation circuit 221 is connected to the sensing probe 12. The first end of the capacitance compensation circuit 222 is connected to the second end of the signal attenuation circuit 221. The first end of the current-voltage conversion circuit 223 is connected to the second end of the capacitance compensation circuit 222. The signal attenuation circuit 221 can weaken the signal driving the quartz tuning fork. The weakened signal can be provided to the quartz tuning fork and the capacitance compensation circuit 222. The output signals of these two lines are superimposed, so that only the piezoelectric current of the quartz tuning fork can be amplified by the current-voltage conversion circuit 223. The signal output by the pre-drive circuit 22 is continuously input to the next stage through the buffer circuit.

[0076] Please also see Figure 5 In one embodiment, the pre-drive circuit 22 includes a plurality of operational amplifiers. This part of the circuit is mainly composed of integrated operational amplifiers. The chip selected for this circuit design is a high-precision, low-power, high-speed operational amplifier. Each chip contains two operational amplifiers, which greatly facilitates the simplification of the circuit board structure and saves circuit space. In this circuit design, the main performance demands are reflected in speed and low noise. The circuit achieves a voltage amplitude change of ±0.01% of the operational amplifier within 1μs, and the high slew rate can also exceed 16V / s. The circuit's high-speed requirement for the operational amplifier is to prevent the signal from being distorted when passing through the circuit, especially to maintain the shape integrity of the high-speed signal. When working on a device with a weak signal such as a quartz tuning fork probe, a high speed is indispensable.

[0077] The self-excitation circuit 23 controls the circuit signal in the form of negative feedback to form a loop, which is linked with the pre-drive circuit 22. The negative feedback automatically controls and adjusts the signal amplitude, so that the signal amplitude and signal phase meet the conditions of self-excitation.

[0078] In one embodiment, the self-excitation circuit 23 includes a programmable gain amplifier circuit 231 , a root mean square circuit 232 , a subtraction circuit 233 , a multiplier 234 , a phase shift circuit 235 and an analog switch 236 .

[0079] The first end of the programmable gain amplifier circuit 231 is connected to the second end of the current-voltage conversion circuit 223. The first end of the root mean square circuit 232 is connected to the second end of the programmable gain amplifier circuit 231. The first end of the subtraction circuit 233 is connected to the second end of the root mean square circuit 232. The first end of the multiplier 234 is connected to the second end of the subtraction circuit 233, and the second end of the multiplier 234 is connected to the second end of the programmable gain amplifier circuit 231. A phase shift circuit 235, the first end of the phase shift circuit 235 is connected to the third end of the multiplier 234. The first end of the analog switch 236 is connected to the second end of the phase shift circuit 235, and the second end of the analog switch 236 is connected to the third end of the signal attenuation circuit 221.

[0080] The programmable gain amplifier circuit 231 can amplify the signal from the pre-driver circuit 22 described above. The next part is the root mean square circuit 232, which is used to measure the root mean square value of the amplitude of the amplified signal. The above two signals: the amplified signal and the root mean square value, are continuously input to the subtraction circuit 233, and after processing, they are passed to the phase shift circuit 235 by the gain control part. In the phase shift circuit 235, the circuit can control a certain phase shift to act on the signal, so that the generated signal can be used as a "driving signal" and monitored. Finally, through an analog switch 236, the signal is sent to the pre-driver circuit 22.

[0081] In the above circuit, the driving of the circuit does not depend on the input of an external signal, but can utilize signals such as noise in the circuit, and after processing such as amplification, drive the probe to work at the resonance frequency. When the driving circuit tends to be stable, the signals in the circuit are only signals with a frequency equal to the resonance frequency of the tuning fork probe (usually a sine signal), and signals of other frequencies are attenuated. In this case, the quartz tuning fork probe can be regarded as a band-pass filter, and because it only selects the resonance frequency and has an extremely narrow passband, it has good frequency selection characteristics and a very high gain at its resonant frequency. In the stable state of the loop, only the loop gain of the signal with a frequency equal to the resonance frequency is equal to 1, and for signals with other frequencies, due to the existence of the band-pass filter, their loop gains are all less than 1, showing different degrees of attenuation. After entering the stable state for a period of time, only the signal with the resonant frequency will remain in the loop.

[0082] The typical working process of the scanning probe microscope system 100 is as follows:

[0083] 1. Install the sample 32 to be scanned. Fix the sample to be tested on the sample stage 32 to be scanned (the sample stage 32 to be scanned is usually a circular iron sheet), and then place the sample stage 32 to be scanned on the piezoelectric scanner 31.

[0084] 2. Install the sensing probe 12. Install the sensing probe 12 on the corresponding probe holder 11, and insert the probe holder 11 into the installation position of the probe holder 11 of the host probe 20.

[0085] 3. Adjust the laser optical path (this step is not required for the tuning fork type self-sensing probe and the scanning tunneling microscope). Adjust the position adjustment knobs (there are 2 knobs, respectively for front-back and left-right position adjustments) of the laser diode 24 on the right side of the host probe 20, so that the emitted laser just irradiates at an appropriate position on the back of the microcantilever probe. Then adjust the position adjustment knobs (there are 2 knobs, respectively for front-back and left-right position adjustments) of the position detector 25 on the right side of the host probe 20, so that the laser emitted by the microcantilever just irradiates at the center position of the position detector 25.

[0086] 4. Measure the probe vibration curve and set parameters (i.e., Q curve measurement, this step is not available for the contact mode AFM and the scanning tunneling microscope). First, apply a sinusoidal voltage excitation signal to the probe to excite its mechanical vibration and measure its amplitude and phase to obtain the Q curve. Second, select signals of appropriate voltage, frequency, amplitude, etc. according to the Q curve to make the probe enter the state of excited vibration.

[0087] 5. Automatically approach the distance between the probe and the sample 32 to be scanned. Set the reference value of the probe sensing signal (for example, the force reference value in AFM is 1 nanonewton), and make the probe tip contact the sample 32 to be scanned and keep the sensing signal equal to the set reference value through an automatic (or manual) method. The automatic approach method is that the coarse adjustment control circuit in the main controller 41 outputs a motor control signal to drive the lead screw in the probe height coarse adjustment assembly 33 in the host base 30 to move downward, so that the host probe 20 moves downward, reducing the distance between the probe and the sample 32 to be scanned until the sensing signal (such as the magnitude of the force) detected by the probe is equal to the reference value.

[0088] It should be noted that in different sensing probes 12 and measurement modes, the sensing signals are different. In the contact mode AFM, the deformation of the probe microcantilever is proportional to the force exerted on the probe; in the tapping mode AFM, the vibration amplitude of the probe microcantilever represents the magnitude of the force exerted on the tip. In the frequency modulation imaging mode of the tuning fork type self-sensing probe, the change in the tuning fork vibration frequency represents the magnitude of the force gradient exerted on the tip. In the scanning tunneling microscope, the distance between the probe and the sample 32 to be measured is adjusted to the nanoscale to generate a stable tunneling current.

[0089] After the automatic approach is completed, the feedback control circuit receives the signal detected by the sensing probe 12 (such as the force signal in AFM), compares it with the set reference value (such as the set magnitude of the force), and then outputs an error signal, and adjusts the voltage value V of the piezoelectric scanner 31 in the vertical direction (Z direction) according to this error signal.z , so as to control the height of the sample 32 to be scanned, so that the effective distance between the probe and the sample 32 to be scanned, or the deformation amount of the probe, or the interaction force remains constant.

[0090] 6. Topography scanning. Under normal imaging conditions, the scanning control circuit in the main controller 41 outputs scanning drive signals in the X and Y directions, so that the piezoelectric scanner 31 generates a scanning grating. By keeping the probe sensing signal constant, point-by-point scanning of the sample 32 to be measured can be realized. The scanned image (such as a topography map) is then displayed and processed by the computer 42 and the measurement and control software.

[0091] 7. Single-point measurement function, including spectral curve measurement. After the topography scanning is completed, the probe can be positioned at a selected position on the sample 32 to be scanned, and the sensing probe 12 is used to perform local characteristic measurement on the sample 32 to be scanned, such as measuring the force-distance curve at this position.

[0092] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0093] The above-described embodiments only represent several implementation manners of the present application. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A scanning probe microscope system, characterized in that, Comprising: A plurality of probe holders, each probe holder being configured to mount a sensing probe; A main body probe, including a pre - circuit and a positioning guide groove, the positioning guide groove being configured to detachably mount the plurality of probe holders, and the probe holders being electrically connected to the pre - circuit; Wherein, the pre - circuit includes: a pre - drive circuit and a self - excitation circuit, a first end of the pre - drive circuit being connected to the sensing probe; the self - excitation circuit and the pre - drive circuit are connected to form a negative feedback loop; The pre - drive circuit includes a signal attenuation circuit, a capacitance compensation circuit, and a current - voltage conversion circuit; A first end of the signal attenuation circuit is connected to the sensing probe; a first end of the capacitance compensation circuit is connected to a second end of the signal attenuation circuit; and a first end of the current - voltage conversion circuit is connected to a second end of the capacitance compensation circuit; The self - excitation circuit includes a programmable gain amplifier circuit, a root - mean - square circuit, a subtraction circuit, a multiplier, a phase - shift circuit, and an analog switch; A first end of the programmable gain amplifier circuit is connected to a second end of the current - voltage conversion circuit; a first end of the root - mean - square circuit is connected to a second end of the programmable gain amplifier circuit; a first end of the subtraction circuit is connected to a second end of the root - mean - square circuit; a first end of the multiplier is connected to a second end of the subtraction circuit, a second end of the multiplier is connected to a second end of the programmable gain amplifier circuit; a first end of the phase - shift circuit is connected to a third end of the multiplier; a first end of the analog switch is connected to a second end of the phase - shift circuit, and a second end of the analog switch is connected to a third end of the signal attenuation circuit; A main body base, configured to support the main body probe and be signal - connected to the sensing probe; and A measurement and control device, signal - connected to the main body base.

2. The scanning probe microscope system according to claim 1, wherein When any one of the plurality of probe holders is mounted in the positioning guide groove, the tip of the sensing probe thereon has a constant position relative to the positioning guide groove.

3. The scanning probe microscope system according to claim 1, wherein The positioning guide groove is configured to mount the plurality of probe holders by an insertion method.

4. The scanning probe microscope system according to claim 1, wherein, The sensing probe includes a self - sensing atomic force probe, a laser - detection atomic force probe, and a scanning tunneling microscope probe.

5. The scanning probe microscope system according to claim 4, wherein, The main body probe further includes: A laser diode, the laser emitted by which irradiates a set position of the laser - detection atomic force probe; and A position detector, the laser reflected from the set position irradiating the center position of the position detector.

6. The scanning probe microscope system according to claim 4, wherein The pre - circuit includes: An identification circuit, electrically connected to the probe holder.

7. The scanning probe microscope system according to any one of claims 1 - 3, characterized in that: A unified electrical interface is adopted between the probe holder and the main body probe.

8. The scanning probe microscope system according to claim 1, characterized in that: The negative feedback loop automatically controls the signal amplitude and adjusts the phase, so that the signal amplitude and signal phase meet the conditions of self - excitation.

9. The scanning probe microscope system according to claim 6, wherein The identification circuit automatically identifies the type of the probe holder and selects and uses the corresponding circuit.

10. The scanning probe microscope system according to claim 1, characterized in that, The pre-drive circuit includes a plurality of operational amplifiers, and the voltage amplitude change of the plurality of operational amplifiers within 1 microsecond is ±0.01%, and the high slew rate is greater than or equal to 16 V / s.

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