Using method of scanning probe microscope and scanning probe microscope

Abstract

The invention provides a use method of a scanning probe microscope, which comprises the following steps: enabling a light beam emitted by a light source to pass through a light modulator and enter a probe arm of a probe, enabling a signal output by the scanning probe microscope to at least respond to a reference signal and a signal output by a detector, enabling the scanning probe microscope to transmit the reference signal to the light modulator when the scanning probe microscope operates in a contact mode, and causing the state of the optical modulator to at least respond to the reference signal; the signal of the surface characteristic of the detected object can be transferred to the frequency corresponding to the reference signal, and the reference signal is combined to filter the signal output by the sensitive detector, so that the signal-to-noise ratio is greatly improved. The invention also provides a scanning probe microscope.

Description

Technical Field

[0001] The present invention belongs to the technical field of scanning probe technology, and particularly relates to a method for using a scanning probe microscope and a scanning probe microscope. Background Art

[0002] A scanning probe microscope (SPM) measures the surface shape of a sample by bringing a probe close to or into contact with the surface of the sample, and has a very wide range of application fields, including the surface structure, physical properties, chemical reactions, nanomanufacturing, information storage and other characteristics of conductors, semiconductors, insulators, biological, organic, nano and other materials. Most of the existing scanning probe microscopes adopt a method called the optical lever method to detect the object to be measured. Specifically, the optical lever method mainly irradiates a laser on the probe arm of the probe, and detects the position change of the laser reflected by the probe through a detector, so as to detect the position and / or posture of the probe, and further obtain the position of the probe tip and / or the interaction force between the tip and the object to be measured.

[0003] The contact mode is an operating mode of a scanning probe microscope. By bringing the tip of the probe into contact with the surface of the object to be measured and forming a relative displacement between the probe and the object to be measured, at least the characteristics including topography of the surface of the object to be measured are scanned and detected. However, during the operation of the contact mode, since the tip of the probe needs to remain in contact with the object to be measured, correspondingly, the signal received by the sensor always contains the signal of the surface characteristics of the object to be measured and the noise signal, and the noise signal cannot be eliminated, resulting in limited detection accuracy in the contact mode.

[0004] The above information disclosed in the background art section is only used to enhance the understanding of the background of the present invention, and thus may include information that does not constitute the prior art known to those of ordinary skill in the art. Summary of the Invention

[0005] Aiming at the problem of insufficient scanning accuracy in the contact mode existing in the prior art, the present application first provides a method for using a scanning probe microscope, enabling a light beam emitted by a light source to pass through a light modulator and be incident on the probe arm of the probe, and the light intensity of the light beam exiting the light modulator responds to the state of the light modulator, and the light beam is incident on a detector after being reflected by the probe arm; The signal output by the scanning probe microscope responds at least to a reference signal and the signal output by the detector; the signal output by the scanning probe microscope can be at least used to analyze the surface characteristics of the object to be measured; When the scanning probe microscope operates in the contact mode: a reference signal is transmitted to the light modulator, and the state of the light modulator responds at least to the reference signal.

[0006] According to an embodiment of the present application, when the scanning probe microscope operates in the tapping mode: the vibration of the driving device that drives the probe arm to vibrate responds to the reference signal.

[0007] According to an embodiment of the present application, the driving device is a piezoelectric block, and the driving voltage of the piezoelectric block responds at least to the reference signal.

[0008] According to an embodiment of the present application, the scanning probe microscope is configured to be able to switch between the tapping mode and the contact mode.

[0009] According to an embodiment of the present application, at least the reference signal and the signal output by the detector are transmitted to a lock-in amplifier, and the signal output by the lock-in amplifier responds at least to the reference signal and the signal output by the detector.

[0010] According to an embodiment of the present application, the signal output by the lock-in amplifier is transmitted to a data processing device, and the signal output by the data processing device is used as the signal output by the scanning probe microscope.

[0011] According to an embodiment of the present application, the reference signal is a periodic signal.

[0012] According to an embodiment of the present application, at least cross-correlation calculation is performed on the reference signal and the signal output by the detector.

[0013] Another aspect of the present application provides a scanning probe microscope, including a light source, an optical modulator, a probe, and a detector. The light beam emitted by the light source passes through the optical modulator and is incident on the probe arm of the probe. The light beam is reflected by the probe arm and then incident on the detector. The detector is configured such that the signal output by it responds at least to the position of the light irradiated thereon; The light intensity of the light beam exiting the optical modulator responds to the state of the optical modulator, and the state of the optical modulator responds to the reference signal; The probe is connected to a driving device, and the probe can vibrate under the drive of the driving device, and the driving device responds to the reference signal.

[0014] According to an embodiment of the present application, the scanning probe microscope further includes a lock-in amplifier, and the lock-in amplifier is communicatively connected to the optical modulator and the detector.

[0015] According to an embodiment of the present application, the scanning probe microscope further includes a stage, and the stage is configured to be able to carry the object to be measured.

[0016] The method for using a scanning probe microscope provided by this application and the scanning probe microscope have at least the following beneficial effects: When operating in the contact mode, the signal of the surface features of the object to be measured is transferred to the frequency corresponding to the reference signal, and the signal output by the sensitive detector is filtered in combination with the reference signal to block the background noise signal mainly composed of low-frequency noise, so as to significantly reduce the proportion of the background noise signal in the signal used to analyze the surface features of the object to be measured, and greatly improve the signal-to-noise ratio. Description of the Drawings

[0017] Figure 1 It is a schematic diagram of an embodiment of a scanning probe microscope provided by this application.

[0018] In the figure: 1, light source; 2, optical modulator; 3, probe; 31, probe arm; 32, tip; 4, detector; 5, driving device; 6, objective lens; 7, lock-in amplifier; 8, data processing device; 9, stage; 10, object to be measured. Detailed Embodiments

[0019] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, rather than all of the embodiments. It should be noted that the accompanying drawings are all in very simplified forms and use non-precise ratios, only for the purpose of conveniently and clearly assisting in explaining the objectives of the embodiments of the present invention.

[0020] This application first provides a method for using a scanning probe microscope, so that the light beam emitted by the light source 1 passes through the optical modulator 2 and is incident on the probe arm 31 of the probe 3, and the light beam is reflected by the probe arm 31 and then incident on the detector 4. The light source 1 is used to emit a light beam, which can be a laser light source, an LED light source, or any other form that can emit light. The optical modulator 2 can adjust at least the characteristics of the light passing through the optical modulator 2, including the light intensity, using the electro-optic or acousto-optic effect; in some cases, the optical modulator 2 can also be a combination of an electro-optic or acousto-optic effect element that can adjust the polarization, phase, frequency, etc. of the light on the basis of the electro-optic or acousto-optic effect and other optical elements, so as to adjust at least the light intensity. The detector 4 can output a corresponding signal according to the position of the light irradiating thereon.

[0021] When detecting the object to be measured 10, the tip 32 of the probe 3 is brought close to the object to be measured 10, and an interaction force is formed between the tip 32 and the measured surface of the object to be measured 10, thereby affecting the state of the position, angle, etc. of the tip 32, and further affecting the state of the position, angle, etc. of the probe arm 31. Thus, by obtaining the state of the position, angle, etc. of the probe arm 31, the interaction force between the tip 31 and the measured surface of the object to be measured 10 can be analyzed, so as to detect the measured surface of the object to be measured 10. The light emitted by the light source 1 is reflected by the probe arm 31 and incident on the detector 4, thereby forming an optical lever to amplify the changes in the position, angle, etc. of the probe arm 31, and reflecting them in the position where the light beam irradiates on the detector 4. Then, by analyzing the signal output by the detector 4, the state of the position, angle, etc. of the tip 31 of the probe 3 can be amplified and analyzed. The detector 4 can be a position-sensitive detector or a quadrant detector.

[0022] The contact mode means that the tip 32 of the probe 3 is in contact with the object to be measured 10. The interaction force between the tip 32 and the object to be measured 10 is mainly the contact force. Different surface topographies of the object to be measured 10 will cause changes in the state of the position, angle, etc. of the tip 32 and the probe arm 31 through the contact force, and then the surface topography or other characteristics of the object to be measured 10 can be analyzed by the optical lever; further, during the relative movement of the probe 3 and the object to be measured 10, the object to be measured 10 is detected, so as to obtain the distribution of the surface topography or other characteristics of the object to be measured 10.

[0023] On the basis of the above, by analyzing the signal output by the detector 4, the state of the position, angle, etc. of the tip 31 of the probe 3 can be amplified and analyzed, and then the surface characteristics of the object to be measured 10 can be analyzed. Correspondingly, the signal output by the scanning probe microscope provided in this application at least responds to the reference signal and the signal output by the detector 4, and can at least be used to analyze the surface of the object to be measured 10. For the signal output by the scanning probe microscope, it can be an image of the surface of the object to be measured 10, or surface characteristic parameters or indicators, or data to be further processed, or data that has been processed, as long as it can be used to directly or indirectly understand the surface characteristics of the object to be measured 10. The signal output by the atomic force microscope responds to the reference signal and the signal output by the detector 4, which means that when at least one of the reference signal and the signal output by the detector 4 changes or changes beyond the preset range, the signal output by the atomic force microscope also changes accordingly.

[0024] When the scanning probe microscope operates in the contact mode, a reference signal is transmitted to the optical modulator 2, and the state of the optical modulator 2 responds at least to the reference signal. On this basis, the state of the optical modulator 2 changes due to the change of the reference signal. Correspondingly, after the light beam emitted by the light source 1 passes through the optical modulator 2, its state also matches the change or state of the reference signal, realizing the modulation of the light beam, so that the state of the light beam irradiating on the probe arm 31 responds to the reference signal.

[0025] In the foregoing manner, when operating in the contact mode, the light beam emitted by the light source 1 is modulated by the reference signal and the optical modulator 2, and the signal of the detector 4 responsive to the surface features of the object 10 to be measured is transferred to the frequency corresponding to the reference signal; by using the reference signal and the signal output by the sensitive detector 4, the surface features of the object 10 to be measured are jointly analyzed, so as to filter the signal output by the sensitive detector 4 by using the reference signal, blocking the background noise signal mainly composed of low-frequency noise, so as to significantly reduce the proportion of the background noise signal in the signal for analyzing the surface features of the object 10 to be measured, greatly improving the signal-to-noise ratio.

[0026] In some cases, the scanning probe microscope can switch between multiple modes. For example, it can switch between the contact mode and the tapping mode. The tapping mode means that the tip 32 of the probe 3 vibrates, and the tip 32 of the probe 3 approaches or contacts the object 10 to be measured. The interaction force between the tip 32 and the object 10 to be measured can be contact force, van der Waals force, electrostatic force, magnetic force, capillary force, chemical bond force, frictional force and other interaction forces. The surface topography or other properties of the object 10 to be measured will cause changes in the position, angle and other states of the tip 32 and the probe arm 31 through the interaction force, and then the surface topography or other features of the object 10 to be measured are analyzed by the optical lever; further, during the relative movement of the probe 3 and the object 10 to be measured, the object 10 to be measured is detected, so as to obtain the distribution of the surface topography or other features of the object 10 to be measured.

[0027] Similarly to the contact mode, when operating in the tapping mode, the vibration of the probe 3 is modulated by the reference signal, and the signal of the detector 4 responsive to the surface features of the object 10 to be measured is transferred to the frequency corresponding to the reference signal. The signal output by the sensitive detector 4 is filtered by using the reference signal, blocking the background noise signal mainly composed of low-frequency noise, so as to significantly reduce the proportion of the background noise signal in the signal for analyzing the surface features of the object 10 to be measured, greatly improving the signal-to-noise ratio. At the same time, in both the contact mode and the tapping mode, the reference signal is used, and there is no need to separately set a noise reduction device, reducing the complexity of the equipment.

[0028] When the scanning probe microscope operates in the tapping mode, the vibration of the driving device 5 that drives the probe arm 31 to vibrate responds to the reference signal. Accordingly, the vibration of the probe arm 31 responds to the reference signal.

[0029] In addition, when the scanning probe microscope is in the tapping mode, the optical modulator 2 can either modulate the light beam passing through the optical modulator 2 in response to changes in the reference signal, or keep the state of the light beam passing through the optical modulator 2 unchanged without responding to changes in the reference signal. In some cases, the optical modulator 2 can be made not to respond to changes in the reference signal in the tapping mode to reduce the algorithm complexity of analyzing the signal of the detector 10, thereby improving the data processing efficiency.

[0030] Please participate Figure 1 , the driving device 5 that drives the probe 3 to vibrate can be a piezoelectric block, and the piezoelectric block can change its shape in response to changes in the driving voltage, thereby converting the change in the driving voltage into the vibration of the probe 3. The driving voltage of the piezoelectric block responds at least to the aforementioned reference signal, so that the vibration of the probe 3 responds to the reference signal.

[0031] The scanning probe microscope provided by this application is configured to be able to switch between the tapping mode and the contact mode. That is to say, the scanning probe microscope at least has the function settings of the tapping mode and the contact mode. Correspondingly, please refer to Figure 1 , this application also provides a scanning probe microscope, including a light source 1, an optical modulator 2, a probe 3, and a detector 4. The light beam emitted by the light source 1 passes through the optical modulator 2 and is incident on the probe arm 31 of the probe 3. The light beam is reflected by the probe arm 31 and then incident on the detector 4. The detector 4 is configured such that the signal output therefrom responds to the position of the light irradiated thereon; the light intensity of the light beam exiting the optical modulator 2 responds to the state of the optical modulator 2, and the state of the optical modulator 2 responds to the reference signal; the probe 3 is connected to the driving device 5, and the probe 3 can vibrate under the drive of the driving device 5, and the driving device 5 responds to the reference signal. In this way, by turning on the light source 1, making the optical modulator 2 respond to the reference signal, receiving the signal output by the detector 4 and the reference signal, the surface characteristics of the object to be measured 10 are detected in the contact mode; by turning on the light source 1, making the driving device 5 of the probe 3 respond to the reference signal, receiving the signal output by the detector 4 and the reference signal, the surface characteristics of the object to be measured 10 are detected in the tapping mode.

[0032] Similarly, the scanning probe microscope provided by the present application can significantly reduce the proportion of the background noise signal in the signal used for analyzing the surface features of the object to be measured 10 in both the contact mode and the tapping mode, greatly improving the signal-to-noise ratio; in both the contact mode and the tapping mode, a reference signal is used without separately setting a noise reduction device, reducing the complexity of the device. For the specific principle implementation method, please refer to the foregoing content and will not be elaborated here.

[0033] In some cases, a lock-in amplifier can be further set up for signal processing. Specifically, in the contact mode and the tapping mode, the lock-in amplifier 7 receives at least the reference signal and the signal output by the detector 4, and makes the signal output by the lock-in amplifier 7 respond at least to the reference signal and the signal output by the detector, and then uses the signal output by the lock-in amplifier 7 to further analyze the surface features of the object to be measured 10, so as to analyze the signal of the detector 4 using the reference signal. As a feasible implementation manner, the reference signal can be used to filter the signal of the detector 4 to filter out the noise signal in the signal of the detector 4.

[0034] In some cases, a data processing device 8 can be further set up to make the signal output by the lock-in amplifier 7 be transmitted to the data processing device 8 for further processing, and use the signal output by the data processing device 8 as the signal output by the scanning probe microscope. As a feasible implementation manner, the data processing device 8 can be a computer device (which can be a personal computer, a server, or a network device, etc.) to analyze the surface features of the object to be measured 10 according to the data output by the lock-in amplifier 7; in some cases, the data processing device 8 can output the surface topography image of the object to be measured 10, or other surface features and their distributions, and the specific output form can be adjusted according to the needs of data display.

[0035] Based on the foregoing technical solution, the reference signal is a periodic signal. Specifically, the periodic signal can be a sine signal, a pulse signal, or other types of periodically changing signals, as long as it can form a corresponding frequency for reducing the noise signal.

[0036] When analyzing the reference signal and the signal output by the detector 4, at least cross-correlation calculation can be performed on the two to filter out the noise signal.

[0037] Please refer to Figure 1, in some cases, the lock-in amplifier 7 is at least communicatively connected to the detector 4 to at least receive the signal from the detector 4. The lock-in amplifier 7 may also be communicatively connected to the optical modulator 2. In some cases, it may transmit a reference signal to the optical modulator 2; in some cases, it may receive a signal of the state of the optical modulator 2, which is equivalent to receiving the reference signal transmitted to the optical modulator 2. The lock-in amplifier 7 may also be communicatively connected to the driving device 5. In some cases, it may transmit a reference signal to the driving device 5, and in some cases, it may also receive a signal corresponding to the state of the driving device 5.

[0038] It can be understood that, in some cases, the reference signal may be generated by the lock-in amplifier 7 and transmitted to at least one of the optical modulator 2 and the driving device 5 through the communication connection when the scanning probe microscope operates in the corresponding state. In addition, the reference signal may also be generated by other components and transmitted to the lock-in amplifier 7.

[0039] In some cases, the optical modulator 2 at least modulates the light intensity of the light passing through it. Specifically, the light intensity of the light beam exiting the optical modulator 2 responds to the state of the optical modulator 2. In some cases, when the reference signal is a periodic signal, the light intensity of the light beam passing through the optical modulator 2 can achieve periodic changes.

[0040] Please refer to Figure 1 , in some cases, the scanning probe microscope provided by the present application may further include a stage 9 for carrying the object to be measured 10. In some cases, the object to be measured 10 can be driven to move by the stage 9 to cooperate with the probe 3 and the corresponding optical path to scan and detect the surface features of the object to be measured 10. In some cases, the position of the object to be measured 10 can also be fixed, and the probe 3 can be moved relative to the object to be measured 10, so as to scan and detect the surface features of the object to be measured 10.

[0041] Please refer to Figure 1 , in some cases, the scanning probe microscope provided by the present application may further include an objective lens 6. The light beam emitted by the light source 1 passes through the optical modulator 2 and the objective lens 6 to converge on the probe arm 31, thereby reducing the loss of the light beam energy, enhancing the intensity of the signal of the detector 4, thereby improving the signal-to-noise ratio and reducing the noise.

[0042] The above shows and describes the basic principles, main features and advantages of the present invention. Therefore, the above are only embodiments of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification is only the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention also includes various equivalent changes and improvements, and these changes and improvements will all fall within the scope of the present invention claimed.

Claims

1. A method for using a scanning probe microscope, characterized in that: Cause the light beam emitted by the light source to pass through the optical modulator and enter the probe arm of the probe. The light intensity of the light beam exiting the optical modulator responds to the state of the optical modulator. The light beam is reflected by the probe arm and then enters the detector. The signal output by the scanning probe microscope responds at least to the reference signal and the signal output by the detector. The signal output by the scanning probe microscope can be at least used to analyze the surface features of the object to be measured. When the scanning probe microscope operates in the contact mode: transmit the reference signal to the optical modulator, and cause the state of the optical modulator to respond at least to the reference signal.

2. The method for using a scanning probe microscope according to claim 1, wherein: When the scanning probe microscope operates in the tapping mode: cause the vibration of the driving device that drives the probe arm to vibrate to respond to the reference signal.

3. The method for using a scanning probe microscope according to claim 2, characterized in that: The driving device is a piezoelectric block, and the driving voltage of the piezoelectric block responds at least to the reference signal.

4. The method for using a scanning probe microscope according to claim 1, characterized in that: At least transmit the reference signal and the signal output by the detector to the lock-in amplifier. The signal output by the lock-in amplifier responds at least to the reference signal and the signal output by the detector.

5. The method for using a scanning probe microscope according to claim 4, wherein: The signal output by the lock-in amplifier is transmitted to the data processing device, and the signal output by the data processing device is used as the signal output by the scanning probe microscope.

6. The method for using a scanning probe microscope according to claim 1, wherein: The reference signal is a periodic signal.

7. The method for using a scanning probe microscope according to claim 1, wherein: At least perform cross-correlation calculation on the reference signal and the signal output by the detector.

8. A scanning probe microscope, characterized in that: It includes a light source, an optical modulator, a probe, and a detector. Cause the light beam emitted by the light source to pass through the optical modulator and enter the probe arm of the probe. The light beam is reflected by the probe arm and then enters the detector. The detector is configured such that the signal output by it responds at least to the form of the position of the light irradiating thereon. The light intensity of the light beam exiting the optical modulator responds to the state of the optical modulator, and the state of the optical modulator responds to the reference signal. The probe is connected to the driving device, and the probe can vibrate under the drive of the driving device. The driving device responds to the reference signal.

9. A scanning probe microscope according to claim 8, wherein: The scanning probe microscope further includes a lock-in amplifier, and the lock-in amplifier is communicatively connected to the optical modulator and the detector.

10. A scanning probe microscope according to claim 8, characterized in that: The scanning probe microscope further includes a stage, and the stage is configured to be able to carry the object to be measured.

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