JP2008256579A - Scanning probe microscope and scanning method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To sample observation data on a sample surface without delaying the measuring time even if adsorptive power by a moisture layer on the sample surface is applied when a probe approaches or comes into contact with the sample. <P>SOLUTION: While the probe 2 is oscillated at a constant oscillation amplitude by an exciting means 3 and an oscillation amplitude controlling means 5, a controlling means 8 makes the probe 2 approach or come into contact with the sample until an interaction force works between the probe 2 and the sample surface S. A detecting means 6 detects the approach or contact of the probe 2 with the sample surface S by detecting the variation of the oscillation frequency of the probe 2 by the interaction force, and samples the observation data. A scanning probe microscope is provided where the probe 2 is temporarily separated from the sample surface after sampling the observation data, and is moved to a next observation point. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a scanning probe microscope that measures various physical property information such as the surface shape and viscoelasticity of a sample by scanning a probe surface close to the surface of the sample, and a scanning method using the same. .

  Scanning probe microscopes such as scanning tunneling microscopes and atomic force microscopes are known as devices capable of observing the shape of a sample surface and measuring physical properties. In particular, the atomic force microscope is widely used as a microscope capable of observing the shape of any sample such as a metal, an insulator, and a living body. At that time, high-resolution measurement is expected without destroying the probe and the sample.

  Current measurement methods of scanning probe microscopes include a contact mode in which the probe is scanned while contacting the sample, and a dynamic force mode (DFM mode: Dynamic Force Microscopy in which the sample surface is scanned while vibrating the probe). Various measurement modes such as Mode) have been devised.

  However, in each measurement mode described above, there is a problem that the probe and the sample surface are worn. In the contact mode, since the probe and the sample surface are in continuous contact, the wear is very large. Also, in the DFM mode, the wear of the probe and the sample surface is small compared to the contact mode, but since the probe and the sample surface are in intermittent contact, the number of contact times, contact pressure, etc. increase. Wear on the probe and sample surface is inevitable.

  Therefore, a non-contact mode based on frequency control is known as a measurement mode for suppressing wear of the probe and the sample surface.

In the non-contact mode by frequency control, the sample surface is scanned while vibrating so that the vibration amplitude is kept constant, and the probe surface is displaced by van der Waals force acting between the probe and the sample surface. The distance between the probe and the sample surface is controlled by controlling the vibration frequency of the probe. In order to detect the attractive force of van der Waals force acting between the probe and the sample surface, it is possible to scan at a position away from the sample surface (non-contact area), and to reduce the wear between the probe and the sample. Can be reduced. (For example, see Non-Patent Document 1)
However, in the non-contact mode, it is difficult to measure a sample having large irregularities such as 100 nm or more. This is because when the unevenness of the sample is large, the shift direction of the vibration frequency of the probe may be reversed, thereby interrupting the measurement and making it impossible to perform a stable measurement.

  Therefore, a scanning probe microscope using a measurement method called an SIS mode is known which can measure the surface shape of a sample with high accuracy even for a sample with large irregularities and can suppress wear of the sample and the probe.

FIG. 7 shows a schematic configuration diagram of a scanning probe microscope using the SIS mode, and FIG. 8 shows a flowchart of a measuring method using the scanning probe microscope. (For example, see Patent Document 1.)
For convenience of explanation, the direction parallel to the sample surface is defined as the XY direction, and the direction perpendicular to the sample surface is defined as the Z direction. Hereinafter, this measurement mode is referred to as SIS mode.

  In step 0, the piezoelectric element 14 is driven by the excitation power source 15, and the cantilever 13 having the probe 2 fixed to the piezoelectric element 14 at the tip is vibrated at a vibration frequency that resonates or forcibly vibrates.

  In step 1, the probe 2 on the cantilever 13 is moved so as to approach the sample surface S by being driven in the Z direction by the three-dimensional actuator 12.

  In step 2, laser light is emitted from the light source 16, and reflected light reflected from the back surface of the cantilever 13 is incident on the photodetector 17 to detect a change in the cantilever 13. This is because the change in the vibration amplitude of the probe 2 due to the interaction force (van der Waals force, repulsive force or attractive force due to contact) between the probe 2 on the cantilever 13 and the sample S is incident on the photodetector 17. When the amplitude attenuation detecting unit 28 detects the reflected light information, the movement of the probe 2 in the Z direction is stopped.

In step 3, observation data is collected at the position where the probe 2 is stopped in step 2. In step 4, the cantilever 13 is moved away from the sample surface S in the Z direction by the three-dimensional actuator 12.

  In step 5, the probe 2 is moved in the XY directions by the three-dimensional actuator 12 to the next observation position. If the amplitude attenuation detector 28 detects that the amplitude of the cantilever 13 is attenuated during scanning in the XY directions, the process proceeds to step 6.

  In Step 6, immediately stop the movement of the cantilever 13 in the X and Y directions, and further move in the Z direction away from the sample P, and then go to Step 5.

  On the other hand, if the cantilever 13 has reached the next observation position, the process proceeds to step 2. By repeating this series of operations, observation data at each observation position is collected, and the surface shape of the sample surface S is obtained.

As described above, in other measurement modes such as the DFM mode, the probe and the sample surface are scanned while contacting or intermittently contacting, while in the SIS mode, the probe is brought close to the sample surface only at the observation position. Since the probe is separated from the sample surface outside the observation position, wear on the sample surface can be minimized.
TRAlbrecht et al. “Frequency modulation detection using high-Q cantilevers for enhanced force microscope sensitivity”, J. Appl. Phys., 69, 668, (1991) JP 2005-69851 A

However, the conventional apparatus described above still has the following problems.
When the probe is brought close to the sample, the probe is affected by adsorption by the moisture layer, etc. on the sample surface. When the probe receives adsorption force, the probe vibration attenuates or stops, so the probe is adsorbed. It is necessary to pull the probe away from the sample until it is detached from the sample and the vibration is restored to the original state. For this reason, the driving distance for separating the probe from the sample increases, and there is a problem that the time for scanning the probe increases and the measurement time increases.

  The present invention solves the above-described problems, detects that the probe and the sample surface have approached the non-contact region, and attenuates or stops the probe vibration due to the adsorption force from the moisture layer on the sample surface. It is an object of the present invention to provide a scanning probe microscope and a scanning method thereof that can avoid the problem and shorten the scanning time.

  In order to solve the above problems, in the scanning probe microscope of the present invention, a probe that can be moved relative to a sample surface in a Z direction perpendicular to an XY direction parallel to the sample surface by a moving means. A needle, vibration means for vibrating the probe at a vibration frequency that resonates or forcibly vibrates, observation means for observing the vibration state of the probe, vibration amplitude control means for keeping the vibration amplitude of the probe constant, and the probe Detecting means for detecting that the probe and the sample surface are approaching or contacting each other from a change in the vibration state of the probe, observation means for collecting observation data on the sample surface, and movement of the probe in the XY direction and movement in the Z direction. Control means for controlling, when the probe reaches each observation position, the control means stops the movement of the probe in the XY directions, and moves the probe in the Z direction to bring it closer to the sample surface. Move the observation means to the observation data If the detection means detects that the probe and the probe are approaching or contacting each other during the movement in the XY direction, the control means causes the probe to move to the next observation position. The needle was moved in the Z direction away from the sample surface.

  In the scanning probe microscope according to the present invention, the oscillating means vibrates the probe at a predetermined vibration frequency, and the vibration amplitude control means performs vibration of the probe based on the output of the vibration state of the probe detected by the observing means. Control was made so that the amplitude was always kept constant. As a result, even if the probe receives an interaction force due to, for example, the probe approaching or contacting the sample surface, the vibration amplitude of the probe is kept constant. The influence can be avoided.

  In the scanning probe microscope according to the present invention, even if the probe approaches the sample surface only at each observation position by the control means, and the probe approaches or contacts the sample surface during movement in the XY direction, Since the probe is immediately pulled away from the sample surface, wear of the probe and the sample can be suppressed.

  Here, the vibration state of the probe means all parameters representing the vibration state, specifically, for example, vibration amplitude, vibration frequency, vibration phase, and the like.

  The observation means may be any means as long as it can observe the vibration state of the probe. Specifically, for example, a photodetector, a laser interferometer, or the like can be used.

  Further, the distance by which the probe is pulled away from the sample surface is preferably, for example, a preset value or until the vibration state of the probe returns to the original state, but is not limited thereto.

  Further, the scanning probe microscope of the present invention is the above-mentioned scanning probe microscope of the present invention, wherein the vibration frequency of the probe changed due to an interaction force received by the probe approaching or contacting the sample surface. When either one of the displacement amount or the displacement rate exceeded a preset value, it was determined that the probe approached or contacted the sample surface.

  Here, the displacement amount of the vibration frequency is preferably a displacement amount based on the vibration frequency in a state where the probe does not receive the interaction force, but is not limited thereto. Further, the displacement rate of the vibration frequency is preferably a displacement rate based on the vibration frequency in a state where the probe is not receiving the interaction force, but is not limited thereto.

  Further, the scanning probe microscope of the present invention is the scanning probe microscope according to any one of the above-described aspects of the present invention, wherein the control means separates the probe from the sample surface after the observation means collects observation data. It was decided to move in the Z direction. Accordingly, since the probe is moved away from the sample surface in the X and Y directions at positions other than the observation position, the distance between the probe and the sample is secured, so that damage due to collision between the probe and the sample surface is ensured. The possibility of this can be reduced.

  Here, the distance by which the probe is pulled away from the sample surface is preferably, for example, a preset value or until the vibration frequency of the probe returns to the original state, but is not limited thereto.

  The scanning probe microscope of the present invention is the scanning probe microscope according to any one of the above-described inventions, wherein when the probe has reached the next observation position by the control means, the probe is once removed from the sample surface. After moving in the Z direction to be separated, the observation data is collected by bringing the probe close to or in contact with the sample surface.

  In the scanning probe microscope of the present invention, in the scanning probe microscope of the present invention, the observation means collects one or more types of observation data. Thereby, since different types of observation data are collected, various observation data can be collected efficiently, and the state of the sample surface can be grasped from various aspects.

  Here, the observation data refers to various data indicating the state of the sample surface, for example, data indicating various physical property characteristics such as shape, elasticity, viscosity, adsorption force, electrical characteristics, and magnetic characteristics.

  Further, the scanning probe microscope of the present invention is the scanning probe microscope according to any one of the above-described inventions, wherein the probe is spaced apart in the Z direction by a certain distance from the position where the probe approaches or contacts the sample surface. The observation means collects at least one type of observation data. As a result, observation data can be collected at the sample surface and at a position away from the sample surface in a certain distance Z direction, and more various observation data can be collected.

  The scanning probe microscope of the present invention is a range from the position where the probe approaches or contacts the sample surface to a position spaced apart in the Z direction by a certain distance in the scanning probe microscope of the present invention. The observation means collects at least one type of observation data at any of a plurality of positions. Thereby, it is possible to observe the spatial distribution of observation data, for example, a three-dimensional magnetic distribution, in a range from the sample surface to a position away from the sample surface in a certain distance Z direction.

  Further, the scanning probe microscope of the present invention is the scanning probe microscope of any of the present invention described above, wherein the observation means is moving while moving the probe in the XY direction parallel to the sample surface to the next observation position. When it was detected that the probe and the sample surface were approached or contacted, at least one type of observation data was collected at the approached or contacted position. Thereby, observation data can be increased without increasing the measurement time.

  In addition, the scanning method of the scanning probe microscope of the present invention includes a probe that is arranged with respect to the sample surface and is capable of relative movement in the Z direction perpendicular to the XY direction parallel to the sample surface. This is a scanning method in which the needle is vibrated at a vibration frequency that resonates or is forced to vibrate, the probe is brought close to the sample surface while the vibration amplitude of the probe is kept constant, and observation data of the sample surface is collected. Then, after the probe reaches the observation position, the probe is brought close to the Z direction perpendicular to the sample surface, and the probe and the sample surface are approached or contacted due to a change in the vibration frequency of the probe. An observation step of stopping movement of the probe in the Z direction and collecting observation data when detecting that, and a scanning step of moving the probe in the XY direction to the next observation position; During the scanning step, the probe and the sample surface When it is detected that the approach or touch, it was decided to have the step of moving the Z direction away the probe from the sample surface.

  In the scanning method of the scanning probe microscope according to the present invention, control is performed so that the vibration amplitude of the probe is always kept constant during the scanning step and the observation step. As a result, even if the probe receives an interaction force due to, for example, the probe approaching or contacting the sample surface, the vibration amplitude of the probe is kept constant. Can be avoided.

  In the scanning probe microscope according to the present invention, the probe may be brought close to the sample surface only at each observation position, and the probe may approach or contact the sample surface during the scanning process. Since the probe is immediately pulled away from the sample surface, wear of the probe and the sample can be suppressed.

  Here, the distance for pulling the probe away from the sample surface is preferably a preset value or until the vibration state of the probe returns to the original state, but is not limited thereto.

  Further, the scanning method of the scanning probe microscope of the present invention is the scanning method of the scanning probe microscope of the present invention, wherein the observation step moves the probe in the Z direction perpendicular to the sample surface, When either one of the displacement amount or the displacement rate of the vibration frequency of the probe, which has been changed by the interaction force received when the probe approaches or contacts the sample surface, exceeds a preset value, It was determined that the probe approached or contacted the sample surface, and the movement of the probe in the Z direction was stopped and observation data was collected.

  Here, the displacement amount of the vibration frequency is preferably a displacement amount based on the vibration frequency in a state where the probe does not receive the interaction force, but is not limited thereto. Further, the displacement rate of the vibration frequency is preferably a displacement rate based on the vibration frequency in a state where the probe is not receiving the interaction force, but is not limited thereto.

  The scanning probe microscope scanning method according to the present invention is the scanning probe microscope scanning method according to any one of the above-described present inventions, wherein after the observation data is collected in the observation step, the probe is separated from the sample surface. The step of moving in the Z direction is included. Thereby, since the probe approaches or contacts the sample surface only at the observation position, wear of the probe and the sample surface can be reduced.

  Further, the scanning method of the scanning probe microscope of the present invention is the scanning method of the scanning probe microscope of any one of the present invention described above, once the probe has reached the next observation position by the scanning step. The method includes moving the needle in the Z direction away from the sample surface.

  Further, the scanning method of the scanning probe microscope of the present invention is the scanning method of the scanning probe microscope of the present invention, wherein the vibration amplitude of the probe in the observation step and the probe of the scanning step in the scanning step are the same. The step of changing the vibration amplitude is included. Thereby, for example, when the vibration amplitude of the probe in the observation step is reduced, the dissipated energy between the probe and the sample surface can be reduced, and wear due to the collision between the probe and the sample surface can be reduced or avoided.

  Further, the scanning method of the scanning probe microscope of the present invention is the scanning method of the scanning probe microscope of the present invention described above, wherein the vibration frequency of the probe in the observation step and the probe in the scanning step are the same. The step of changing the vibration frequency is included.

  Further, the scanning method of the scanning probe microscope of the present invention is the scanning method of the scanning probe microscope of any of the present invention, wherein the probe is detected to approach or contact the sample surface during the observation step. A displacement amount or a displacement rate of the vibration frequency of the probe, and a displacement amount or a displacement rate of the vibration frequency of the probe that detects that the probe approaches or contacts the sample surface during the scanning step. It was decided to have a process to change. Thereby, for example, if the detection sensitivity during the scanning process is set to a higher sensitivity, wear due to collision between the probe and the sample surface can be reduced or avoided.

  A scanning probe microscope scanning method according to the present invention is the scanning probe microscope scanning method according to any one of the above-mentioned present inventions, wherein the probe approaches a certain distance in the Z direction from a position where the probe approaches or contacts the sample surface. It was decided to have a step of collecting at least one or more types of observation data at the separated positions. Thereby, observation data can be collected at the sample surface and at a position away from the sample surface in a certain distance Z direction.

  Further, the scanning method of the scanning probe microscope of the present invention is the scanning method of the scanning probe microscope of any of the above-described present invention, wherein a certain distance from the position where the probe and the sample surface approach or contact each other in the Z direction. The method includes a step of collecting one or more types of observation data at an arbitrary plurality of positions within a range up to a position separated from each other. Thereby, it is possible to observe the spatial distribution of observation data, for example, a three-dimensional magnetic distribution, in a range from the sample surface to a position away from the sample surface in a certain distance Z direction.

  According to the scanning probe microscope and its scanning method of the present invention, when the probe and the sample surface approach or come into contact with each other, the vibration amplitude of the probe is kept constant by the vibration means and the vibration amplitude control means. Even if the probe receives an adsorption force due to the moisture layer on the sample surface, it is possible to avoid the vibration of the probe from being attenuated or stopped by the adsorption force, so that the scanning time can be shortened, that is, the measurement time can be shortened. it can.

  In addition, when the detecting means detects that the probe and the sample surface are approaching or contacting from the displacement amount or displacement rate of the vibration frequency of the probe, the unevenness that is difficult in the non-contact mode by the conventional frequency control is detected. Even for large samples, stable measurement is possible because the probe is moved close to the preset value only at each observation position until the probe is moved to a preset value, and the probe is moved away from the sample surface after collection of observation data. It can be performed. That is, measurement in a non-contact region that is an advantage of frequency control is possible.

  The scanning probe microscope according to the first embodiment of the present invention will be described below.

  FIG. 1 is a schematic configuration diagram showing a scanning probe microscope according to the present invention.

As shown in FIG. 1, the scanning probe microscope 1 according to the present invention has a cantilever having a probe 2 at the tip thereof arranged so that the tip of the sample P faces the surface S of the sample P placed on the sample stage 11. 13 and the vibration means 3 that resonates or forcibly vibrates the cantilever 13 at the vibration frequency (f _S ), and the vibration state (for example, vibration amplitude and vibration frequency) of the cantilever 13 that is vibrated by the vibration means 3 is observed. The observation means 4, the vibration amplitude control means 5 for keeping the vibration amplitude of the probe 2 constant based on the output of the observation means 4, and the probe 2 and the sample surface S approach or contact based on the output of the observation means 4. The detection means 6 for detecting the change (Δf) in the vibration frequency of the cantilever 13 due to the above, the observation means 7 for collecting observation data when the probe 2 and the sample surface S approach or contact, and the sample of the probe 2 Parallel to surface S Control means 8 for controlling movement in the XY direction and movement in the Z direction perpendicular to the sample surface S is provided.

  Further, the other end of the cantilever 13 provided with the probe is fixed to the piezoelectric element 14. The piezoelectric element 14 has a function of resonating or forcibly oscillating the cantilever 13 with an excitation power source 15. That is, the piezoelectric element 14 and the vibration power source 15 constitute the vibration means 3.

When the cantilever 13 is vibrated at the vibration frequency (f _S ) by the piezoelectric element 14, the probe 2 also vibrates at the vibration frequency (f _S ) in the Z direction perpendicular to the sample surface S.

  The piezoelectric element 14 is attached to the three-dimensional actuator 12. The three-dimensional actuator 12 can move the probe 2 in the XY direction parallel to the sample surface S and the Z direction perpendicular to the sample surface S via the piezoelectric element 14 and the cantilever 13.

  The upper surface of the cantilever 13 is a reflecting surface, and the laser light L is emitted from the light source 16 onto the surface. The reflected light R reflected from the upper surface of the cantilever 13 is detected by the photodetector 17. The photodetector 17 uses, for example, a four-divided photodiode, and can measure a change in position of the reflected light R from a difference in intensity of detection signals detected when the reflected light R enters each photodiode.

  In the present embodiment, the position change of the reflected light R of the vibrating cantilever 13, that is, the vibration state (vibration amplitude, vibration frequency, vibration phase, etc.) of the probe 2 can be detected. That is, the observation means 4 is constituted by the light source 16 and the photodetector 17.

  The detection signal obtained by the photodetector 17 is amplified by the amplifier 18 and sent to the vibration amplitude control means 5 and the detection means 6.

  The signal sent from the amplifier 18 is sent to the excitation power source 15 through the amplitude adjustment circuit 19 and the phase adjustment circuit 20 that constitute the vibration amplitude control means 5.

  The amplitude adjustment circuit 19 is controlled so that the amplitude of the output signal of the observation means 4 is always constant, and the controlled signal is phase-adjusted by the phase adjustment circuit 20 and then supplied to the excitation power source 15. Therefore, the vibration amplitude of the cantilever 13 is always kept constant.

  For example, when the probe receives an adsorbing force from the moisture layer on the sample surface and the vibration amplitude of the cantilever 13 increases or decreases, the observation means 4 detects the vibration amplitude change, and excites a signal that cancels the change. In order to send the power to the power supply 15, feedback is applied so that the change in the vibration amplitude is canceled and the vibration is continued at a constant amplitude. That is, the amplitude adjustment circuit 19 and the phase adjustment circuit 20 constitute the vibration amplitude control means 5.

When the vibration amplitude of the cantilever 13 is kept constant by the vibration amplitude control means 5 as described above, when the probe 2 and the sample P approach to a distance where an interaction force such as an atomic force works, the interaction force As a result, the vibration frequency of the cantilever 13 changes. The vibration frequency of the cantilever 13 is amplified by the amplifier 18 as a detection signal of the observation means 4, then converted to a voltage according to the vibration frequency by the frequency-voltage converter 21, and sent to the voltage displacement detection unit 22. . In the voltage displacement detection unit 22, the signal voltage (V) sent from the frequency-voltage converter 21 and the voltage (V _S ) corresponding to the vibration frequency (f _S ) in the normal state not receiving the interaction force. (ΔV = V−V _S : That is, the displacement of the vibration frequency) is obtained. When this voltage displacement (ΔV) exceeds a preset value (V _t : hereinafter referred to as threshold voltage), the information is sent to the control unit 23.

  That is, the frequency-voltage converter 21 and the voltage displacement detector 22 constitute the detection means 6.

  Although the displacement of the vibration frequency is used for detecting the displacement of the vibration frequency, the displacement rate of the vibration frequency may be used.

  Connected to the three-dimensional actuator 12 are an XY-direction drive unit 24 and a Z-direction drive unit 25 that drive the three-dimensional actuator to scan the probe 2 in the XYZ directions. The XY direction driving unit 24 and the Z direction driving unit 25 are controlled by the control unit 23. The control unit 23 controls the Z direction driving unit 25 based on the signal from the detection means 6. That is, the three-dimensional actuator 12, the control unit 23, the XY direction driving unit 24, and the Z direction driving unit 25 constitute a control unit 8.

  Further, the control unit 23 receives the fact that the detection means 6 detects the approach or contact between the probe 2 and the sample surface S when the vibration frequency of the probe 2 changes and exceeds a set value. The position data of the probe 2 in the XYZ directions at the time is sent to the data storage unit 26. The data storage unit 26 collects and stores the position data as observation data and displays it on a display unit 27 such as a monitor. That is, the observation data displayed on the display unit 27 represents the surface shape of the sample surface S. In other words, the data storage unit 26 and the display unit 27 constitute the observation means 7.

  Further, the control means 8 transmits position data from the control unit 23 to the data storage unit 26 and controls the Z direction driving unit 25 so that the probe 2 is separated from the sample surface S, and the probe 2 is moved to the next observation position. To the XY direction parallel to the sample surface S.

  When the probe 2 is being scanned in the XY directions, if it is detected that the change in the vibration state of the probe 2 has changed beyond a preset value, the scanning in the XY directions is stopped and the probe 2 is stopped. The needle 2 is moved in the Z direction away from the sample surface S.

  That is, the control means 8 moves the probe 2 on the cantilever 13 away from the sample surface S when the detection means 6 detects that the vibration frequency of the cantilever 13 has changed to a preset value or higher during any movement. Move in the direction.

The distance at which the probe 2 is moved away from the sample P in the Z direction may be a preset distance or until the vibration frequency of the probe 2 returns to the original state (f _S ).

  Here, a specific example of measuring the surface shape of the sample surface S with the scanning probe microscope 1 configured as described above will be described with reference to FIGS.

  FIG. 2 is a flowchart showing an example of a process of generating the surface shape of the sample surface S in the present embodiment. FIG. 3 is a conceptual diagram showing the operation of the probe 2 in this embodiment.

  First, as step 1, the cantilever 13 and the probe 2 are vibrated at the vibration frequency by the vibration means 3. The probe 2 is controlled by the vibration means 3, the observation means 4 and the vibration amplitude control means 5 so that the vibration amplitude becomes constant.

  Next, as step 2, in a state where the probe 2 is oscillating with a constant amplitude, the control unit 23 controls the Z direction driving unit 25 to drive the three-dimensional actuator 12, and the probe 2 is moved to the sample P. To a distance to receive interaction force such as interatomic force. At this time, in the present embodiment, the probe 2 is not scanned in the XY directions.

  As Step 3, when the probe 2 approaches the sample surface S and receives an interaction force, the vibration frequency of the probe 2 changes. The detecting means 6 detects this change in vibration frequency. When the change exceeds a preset value, the detection means 6 sends the information to the control unit 23, and the control unit 23 controls the Z-direction drive unit 25 to stop the three-dimensional actuator 12 and Stop moving.

  In the present embodiment, the detection means 6 detects that the probe 2 has approached or contacted the sample surface S from the amount of displacement of the vibration frequency of the probe 2. However, the present invention is not limited to this. Rate may be used.

  Next, in step 4, the control unit 23 sends the position information at which the probe 2 is stopped (the position in the XY direction and the position in the Z direction) to the data storage unit 26 as observation data.

Further, in step 5, the control unit 23 controls the Z direction driving unit 25 to move the probe 2 in the Z direction away from the sample P, for example, by 10 nm. The movement distance in the Z direction is not limited to 10 nm, and may be until the vibration frequency of the probe 2 returns to the original state (f _S ), for example.

  Note that the order of step 4 and step 5 may be reversed, or may be simultaneous. Further, step 3, step 4 and step 5 may all be performed simultaneously.

  Further, step 5 may be omitted and the process may proceed to step 6 immediately. In this case, even if the probe 2 immediately approaches or comes into contact with the sample surface S, in Step 7, the control means 23 immediately controls the Z-direction drive unit 25 to drive the three-dimensional actuator 12, and the probe 2 is moved. Since the probe is moved in the Z direction to be separated from the sample surface S, the probe and the sample surface do not collide.

  After the above process is completed, as step 6, the control unit 23 controls the XY direction driving unit 24 to drive the three-dimensional actuator 12, and scans the probe 2 in the XY direction so as to reach the next observation position.

  During the scanning in the XY directions, if the probe 2 approaches or comes into contact with the convex portion or the like of the sample surface S, the detection means 6 has approached or contacted the probe 2 and the sample surface S as in step 3. Is sent to the control unit 23, and the process proceeds to Step 7. On the other hand, when the probe 2 and the sample P do not approach and the probe 2 reaches the next observation position, the process proceeds to step 2 and the operations from step 2 to step 6 are performed.

If the probe 2 and the sample surface S approach or come into contact, the process proceeds to step 7. In step 7, the control unit 23 controls the XY direction driving unit 24 to stop the driving of the three-dimensional actuator 12 in the XY direction, and to move the probe 2 and the sample P in the Z direction, for example, 10 nm away. Then, the Z direction driving unit 25 is controlled to drive the three-dimensional actuator 12 in the Z direction. The moving distance in the Z direction is not limited to 10 nm, or may be until the vibration frequency of the probe 2 returns to the original state (f _S ).

  After step 7 is completed, the process proceeds to step 6. That is, the control unit 23 controls the XY direction driving unit 24 to move the probe 2 again in the XY direction so that the probe 2 reaches the next observation position. If the probe 2 and the sample surface S approach or contact again during the scanning in the XY directions, the process proceeds to step 7. In this way, Step 6 and Step 7 are repeated until the probe 2 reaches the next observation position.

  When the probe 2 reaches the next observation position by the above process, the process proceeds to step 2 and the observation data at the new observation position is collected.

  By repeating Step 2 to Step 6 and Step 7 in this way, observation data at each observation position is accumulated in the data accumulation unit 26, and observation data at all observation positions is collected. A shape image of the sample surface S can be obtained from the collected observation data. In addition, a surface shape image of the sample surface S can be displayed on the display unit 27.

  In the scanning probe microscope of the present invention, even if the probe 2 receives the adsorption force by the moisture layer on the sample surface S, the vibration amplitude of the probe 2 is kept constant by the vibration amplitude control means 5. 2 is not stopped and the vibration amplitude is not attenuated. In the prior art, since the vibration of the probe 2 is stopped or attenuated by this adsorption force, it is necessary to separate the probe 2 from the sample P until it is separated from the adsorption and the vibration of the probe 2 is restored to the original state. Was causing a time delay. In the present invention, since the probe 2 is always vibrated with a constant amplitude, the vibration of the probe 2 is not stopped or attenuated by the adsorption force, and the measurement time can be shortened.

  Further, in FIG. 2 and FIG. 3, “Step 1” is displayed as “S1” for the sake of convenience, and the same applies to Step 2 to Step 7. Further, in FIG. 3, the operation of the probe 2 is represented on the XZ plane, but the present invention is not limited to this, and may be the YZ plane, for example. In FIG. 3, the positions in the X direction of step 2 (S2) and step 5 (S5) are different, but this is because the figure is simplified, and the position of the probe 2 in the XY direction in actual operation. Are the same.

  Next, a second embodiment according to the present invention will be described with reference to FIGS. FIG. 4 is a flowchart showing an example of a process for generating the surface shape of the sample surface S in the present embodiment. FIG. 5 is a conceptual diagram showing the operation of the probe 2 in this embodiment.

  The difference between the second embodiment and the first embodiment is that, in the first embodiment, the control unit 23 moves the probe 2 to the sample surface S as soon as the probe 2 reaches the next observation position in step 6. In contrast, in the scanning probe microscope according to the second embodiment, after the probe 2 in step 6 has reached the next observation position, the control unit 23 next moves the probe 2 from the sample P in step 8. The point is that the probe 2 is moved closer to the sample surface S after being moved once in the Z direction. That is, in FIG. 4 and FIG. 5, step 8 (S8) for moving in the Z direction away from the probe 2 and the sample surface S is added.

  That is, as in the first embodiment, the control unit 23 brings the probe 2 close to the sample surface S and collects observation data by the steps 1 to 6 and 7, and the probe 2 is removed from the sample surface S. After being separated, it is moved in the XY directions to reach the next observation position. Thereafter, in step 8, the control unit 23 controls the Z direction driving unit 25 to move the probe 2 in the Z direction, which is once pulled away from the sample surface S, and then approaches the probe 2 toward the sample P.

  Note that the distance by which the probe 2 is pulled up in step 8 may be the same distance as in step 5 or a different distance. 4 and 5, “Step 1” is displayed as “S1” for the sake of convenience, and the same applies to Step 2 to Step 8. In FIG. 4, the operation of the probe 2 is shown on the XZ plane. However, the present invention is not limited to this. For example, the YZ plane may be used. Further, in FIG. 5, the positions in the X direction of step 2 (S2), step 5 (S5), and step 8 (S8) are different because this is a simplified diagram, and in actual operation, the probe is The positions of 2 in the XY direction are the same.

  Next, a third embodiment according to the present invention will be described with reference to FIG. FIG. 6 is a flowchart showing an example of a process for generating the surface shape of the sample surface S in the present embodiment.

  The third embodiment is different from the first embodiment in that, in the first embodiment, the vibration means 3 and the vibration amplitude control means 5 always vibrate the probe 2 with a constant amplitude. In the scanning probe microscope of the third embodiment, the probe 2 in the step (step 1 to step 5) in which the probe 2 approaches the sample surface S and the observation data is collected by the vibration means 3 and the vibration amplitude control means 5. And the vibration amplitude (hereinafter, scanning amplitude) of the probe 2 in the step (step 6 and step 7) in which the probe 2 moves to the next observation position. .

  That is, as in the first embodiment, the control unit 23 brings the probe 2 close to the sample surface S and collects observation data and pulls the probe 2 away from the sample surface S by the steps 1 to 5. The observation amplitude is used as the vibration amplitude of the probe 2 in this step.

  As step 9, after step 5, the vibration amplitude of the probe 2 is changed from the observation amplitude to the scanning amplitude by the vibration means 3 and the vibration amplitude control means 5.

  After the vibration amplitude of the probe 2 is changed in step 9, the probe 2 is moved to the next observation position in steps 6 and 7.

  In step 10, after the probe 2 reaches the next observation position, the vibration amplitude of the probe 2 is changed from the scanning vibration amplitude to the observation amplitude by the vibration means 3 and the vibration amplitude control means 5.

  In this way, by changing the vibration amplitude according to the state of the probe 2, for example, if the scanning vibration amplitude is increased, the response becomes higher. Therefore, the probe 2 is moved to the next observation point during the moving process. It is possible to prevent the probe 2 from colliding with the sample surface S after the change of the vibration frequency due to the approach to the sample surface S or the like until the probe 2 is pulled up. Therefore, damage due to collision between the probe 2 and the sample P can be reduced or avoided during the scanning process.

  Here, in step 9 and step 10, the vibration amplitude of the probe 2 is changed, but the vibration frequency of the probe 2 may be used.

Here, the vibration amplitude of the probe 2 is changed in step 9 and step 10, but the threshold voltage (V _t ) used when detecting that the probe 2 and the sample surface S are approaching or contacting each other is set. It may be changed.

  Step 9 is after step 5, but not limited to this, step 5 and step 11 may be performed simultaneously, or step 6 and step 9 may be performed simultaneously. In addition, as in the second embodiment, step 8 (that is, the probe 2 is once lifted and then brought close to the sample) may be incorporated. In that case, step 8 may be before or after step 12. Or it may be simultaneous.

  In FIG. 6, for the sake of convenience, “Step 1” is displayed as “S1”, and Steps 2 to 7 and Steps 9 and 10 are the same.

  The above is description about each embodiment by this invention, However, The technical scope of this invention is not limited to the said embodiment, A various change is added in the range which does not deviate from the meaning of this invention. Is possible.

  For example, in each of the above embodiments, the observation means collects the probe position data as the observation data. However, the observation means is not limited to this. It doesn't matter.

  Furthermore, instead of collecting only one of these observation data, a plurality of observation data (for example, position data and viscosity) may be collected. As a result, more effective observation data can be collected, and the sample P can be observed in a multifaceted manner at a time.

  The observation means may collect one or more types of observation data at a position where the probe is close to or in contact with the sample surface and a position where the probe is separated from the sample surface by a distance h. As a result, data at two locations, i.e., the sample surface and a position h away from the sample surface, can be collected, and a physical property amount or the like corresponding to the distance from the sample surface can be observed.

  Furthermore, observation data may be collected at a plurality of arbitrary positions within a range from the sample surface to a position separated from the sample surface by a distance h as a position for collecting observation data. Thereby, the spatial distribution of the observation data on the sample surface can be observed, and for example, a three-dimensional distribution such as a magnetic field and an electric field can be obtained.

  In each of the above embodiments, the position at which the probe approaches or contacts the sample surface while moving the probe in the XY direction parallel to the sample surface to the next observation position may be added to the observation data as the observation position. . Thereby, observation data can be increased without changing the measurement time.

  In addition, the amount of displacement of the cantilever was detected using a photodetector. However, the detection is not limited to a cantilever using a photodetector. For example, self-detection that measures the amount of vibration displacement of a cantilever by detecting changes in the capacity of the cantilever A mold lever may be used.

  The vibration direction of the probe is the Z direction perpendicular to the sample surface, but the vibration direction of the probe may be any direction, for example, it may be vibrated in a direction parallel to the sample surface.

  Further, the probe is driven by the three-dimensional actuator. However, the present invention is not limited to this, and the probe and the sample may be moved relatively. For example, the sample may be driven by the three-dimensional actuator.

  Although the three-dimensional actuator is integrated, the present invention is not limited to this, and the three-dimensional actuator may be divided, for example, the probe may be driven by a Z-direction actuator, and the sample may be driven by an XY-direction actuator.

  Moreover, although the cantilever is vibrated by the piezoelectric element, the present invention is not limited thereto, and for example, a crystal resonator may be used.

  Further, although the four-split optical photodiode is used as the photodetector 17, the present invention is not limited to this, and for example, a two-split optical photodiode may be used.

It is a schematic block diagram of the scanning probe microscope in 1st embodiment of this invention. It is a flowchart which shows an example of the sample surface measuring method in 1st embodiment of this invention. It is a conceptual diagram which shows operation | movement of the probe in 1st embodiment of this invention. It is a flowchart which shows an example of the sample surface measuring method in 2nd embodiment of this invention. It is a conceptual diagram which shows the operation | movement of the probe in 2nd embodiment of this invention. It is a flowchart which shows an example of the sample surface measuring method in 3rd embodiment of this invention. It is a schematic block diagram of the scanning probe microscope by a prior art. It is a flowchart which shows an example of the measuring method by the scanning probe microscope by a prior art.

Explanation of symbols

P Sample S Sample surface L Laser light R Reflected light 1 Scanning probe microscope 2 Probe 3 Excitation means 4 Observation means 5 Vibration amplitude control means 6 Detection means 7 Observation means 8 Control means 11 Sample stage 12 Three-dimensional actuator 13 Cantilever 14 Piezoelectric element 15 Excitation power source 16 Light source 17 Photo detector 18 Amplifier 19 Amplitude adjustment circuit 20 Phase adjustment circuit 21 Frequency-voltage converter 22 Voltage displacement detection unit 23 Control unit 24 XY direction drive unit 25 Z direction drive unit 26 Data storage unit 27 Display unit 28 Amplitude attenuation detection unit

Claims (17)

A probe arranged relative to the sample surface and capable of relative movement in the Z direction perpendicular to the XY direction parallel to the sample surface;
Vibration means for vibrating the probe at a vibration frequency for resonance or forced vibration;
Observation means for observing the vibration state of the probe;
Vibration amplitude control means for keeping the vibration amplitude of the probe constant;
Detecting means for detecting that the probe and the sample surface are approaching or in contact with each other from a change in a vibration state of the probe;
Observation means for collecting observation data of the sample surface;
Control means for controlling movement in the XY direction and movement in the Z direction,
The control means moves the probe in the Z direction to approach the sample surface;
The observation means collects observation data,
When the probe is moved in the XY direction until it reaches the next observation position, and the detection means detects that the probe and the probe are approaching or contacting during movement in the XY direction The scanning means moves the probe in the Z direction away from the sample surface. The scanning probe microscope according to claim 1,
The detection means detects that the probe has approached or contacted the sample surface when at least one of the displacement amount or displacement rate of the vibration frequency of the probe exceeded a preset value. A scanning probe microscope. The scanning probe microscope according to claim 1,
The scanning probe microscope characterized in that the control means moves the probe in the Z direction away from the sample surface after the observation means collects observation data. The scanning probe microscope according to any one of claims 1 to 3,
The control means moves the probe in the XY direction until it reaches the next observation position, and once moves the probe in the Z direction away from the sample surface, the probe is then moved to the sample. A scanning probe microscope characterized by being moved in the Z direction approaching the surface. The scanning probe microscope according to any one of claims 1 to 4,
The scanning probe microscope characterized in that the observation means collects at least one type of observation data at a position where the probe approaches or contacts the sample surface. In the scanning probe microscope in any one of Claim 1 to 5,
The scanning probe microscope characterized in that the observation means collects at least one type of observation data at a position separated in the Z direction by a certain distance from a position where the probe approaches or contacts the sample surface. In the scanning probe microscope in any one of Claim 1 to 5,
The observation means collects at least one type of observation data at a plurality of arbitrary positions within a range from a position at which the probe approaches or contacts the sample surface to a position separated by a certain distance in the Z direction. A scanning probe microscope characterized by the above. The scanning probe microscope according to any one of claims 1 to 7,
The observation means detects that the probe approaches the probe surface and the sample surface while the control means moves the probe to the next observation position in the XY direction parallel to the sample surface. A scanning probe microscope characterized in that at least one type of observation data is collected at a detected position. A probe arranged relative to the sample surface and capable of relative movement in the Z direction perpendicular to the XY direction parallel to the sample surface, and oscillating the probe at a vibration frequency that resonates or forcibly oscillates; A scanning method of a scanning probe microscope for obtaining observation data of the sample surface by bringing the probe close to the sample surface with the vibration amplitude of the probe kept constant,
The probe is approached in the Z direction perpendicular to the sample surface at the observation position, and the probe and the sample surface are detected to approach or contact from the change in the vibration state of the probe. An observation step of stopping movement of the needle in the Z direction and collecting observation data;
A scanning step of moving the probe in the XY direction to the next observation position;
A step of moving the probe in the Z direction away from the sample surface when detecting that the probe and the sample surface approach or contact each other during the scanning step. Scanning method of scanning probe microscope. The scanning probe microscope scanning method according to claim 9,
In the observation step, the probe is brought close to the Z direction perpendicular to the sample surface at the observation position, and at least one of the displacement amount or displacement rate of the vibration frequency of the probe exceeds a preset value. By this, when detecting that the probe and the sample surface are approaching or contacting each other, the scanning type is a step of stopping the movement of the probe in the Z direction and collecting observation data Probe microscope scanning method. In the scanning method of the scanning probe microscope in any one of Claim 9 to 10,
A scanning probe microscope scanning method comprising a step of moving the probe in the Z direction away from the sample surface after the observation step. In the scanning method of the scanning probe microscope in any one of Claim 9 to 11,
A scanning probe microscope scanning method comprising the step of temporarily moving the probe in the Z direction away from the sample surface when the probe reaches the next observation position in the scanning step. In the scanning method of the scanning probe microscope in any one of Claim 9 to 12,
A scanning probe microscope scanning method comprising a step of changing a vibration amplitude of the probe in the observation step and a vibration amplitude of the probe in the scanning step. In the scanning method of the scanning probe microscope in any one of Claim 9 to 13,
A scanning probe microscope scanning method comprising a step of changing a vibration frequency of the probe in the observation step and a vibration frequency of the probe in the scanning step. In the scanning method of the scanning probe microscope in any one of Claim 10 to 14,
A displacement amount or displacement rate of the vibration frequency of the probe that detects that the probe approaches or contacts the sample surface during the observation step, and the probe approaches the sample surface during the scanning step. A scanning method for a scanning probe microscope, comprising: changing a displacement amount or a displacement rate of the vibration frequency of the probe for detecting contact. In the scanning method of the scanning probe microscope in any one of Claim 9 to 15,
A scanning method for a scanning probe microscope, comprising a step of collecting at least one type of observation data at a position spaced apart in the Z direction by a predetermined distance from a position where the probe approaches or contacts the sample surface . In the scanning method of the scanning probe microscope in any one of Claim 9 to 15,
Collecting at least one type of observation data at any of a plurality of positions within a range from a position where the probe approaches or contacts the sample surface to a position separated in the Z direction by a certain distance. A scanning method of a scanning probe microscope, which is characterized.

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