JPH11271340A - Scanning type probe microscope with scanner damage prevention mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a scanning type probe microscope where a piezoelectric body scanner is less frequently damaged due to the application of excessive force. SOLUTION: One end of a tube-type piezoelectric body scanner 1 is fixed to a fixing stand 2, and a stage 3 is fixed to the other end. A mirror 4 is fixed to the reverse side of the stage 3. Light being radiated from a light source 8 is reflected by a polarization beam splitter 6 and enters the mirror 4. Reflection light from the mirror 4 passes through the polarization beam splitter 6 and is condensed on the light reception surface of a position detector 9 by a lens 7. An operation circuit 20 obtains the inclination of the mirror 4, namely the displacement of the scanner 1, based on the output of the position detector 9. A controller 21 drives a warning means 22 when the displacement of the scanner 1 exceeds a tolerance based on information from the operation circuit 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a scanning probe microscope capable of measuring surface information of a sample with atomic order resolution.

[0002]

2. Description of the Related Art Scanning probe microscope (SPM: Scanning P)
robe Microscope) is a scanning tunneling microscope (ST
M: Scanning Tunneling Microscope) and Atomic Force Microscope
(AFM: Atomic Force Microscope) is particularly famous.

The scanning tunneling microscope is the first scanning probe microscope. By utilizing a tunnel current flowing between a metal probe and a conductive sample in close proximity to each other, the surface shape of the sample at an atomic order resolution can be obtained. The measurement has been realized. In the scanning probe microscope, a sample that can be observed is limited to a conductive sample because a tunnel current is used.

The atomic force microscope is a device developed using STM technology such as servo technology, and uses atomic force acting between atoms on the tip of a probe and the surface of a sample to obtain an atomic-order resolution. The measurement of the surface shape of the sample is realized. For this reason, the sample that can be observed is not limited to a conductive sample, and an insulating sample can be measured.

In order to realize a high resolution in a scanning probe microscope, a scanning mechanism capable of controlling the relative position between the probe and the sample with high accuracy is required. In general, a piezoelectric scanner is used.

A scanning probe microscope is a sample scanning type in which a probe is moved by moving a sample, and a probe sample is moved by moving a probe, depending on a difference in an object to be scanned by a scanning mechanism. It is divided into a probe scanning type that performs scanning between them.

[0007]

The piezoelectric scanner, which is the mainstream of the scanning mechanism of the scanning probe microscope, is a relatively brittle and fragile component. In a scanning probe microscope, when a sample is exchanged or a probe is exchanged, an excessive force is applied to the piezoelectric scanner, and the piezoelectric scanner may be damaged.

In particular, in a probe-scanning scanning probe microscope, when a cantilever tip having a probe is attached, it is determined whether or not the tip is correctly attached by pushing the cantilever tip to confirm that there is no backlash. Is going. For this reason, excessive force is applied to the piezoelectric scanner, and the piezoelectric scanner is frequently damaged.

Further, in the scanning probe microscope, before the measurement, the structure supporting the probe and the structure holding the sample are roughly moved in order to roughly approximate the probe and the sample to a predetermined distance. When approaching, the malfunction of this approach causes the approach operation to be continued even though the probe and the sample are already in contact, and excessive force is applied to the piezoelectric scanner, and the piezoelectric scanner may be damaged. is there.

Further, while the XY stage is being evacuated for the purpose of exchanging the sample, for example, the structure supported by the piezoelectric scanner is lowered too much by some mistake, and the XY stage is moved without knowing it. , Because the XY stage hit the structure and was located at an inappropriate height,
This may cause breakage due to excessive force applied to the piezoelectric scanner.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a scanning probe microscope in which a piezoelectric scanner is less frequently damaged by an excessive force. is there.

[0012]

SUMMARY OF THE INVENTION The present invention relates to a scanning probe microscope provided with a mechanism for preventing breakage of a piezoelectric scanner for providing relative scanning between a probe and a sample. Has external force detecting means for detecting an external force applied to the piezoelectric scanner, and warning means for urging the operator's attention, and the external force detecting means drives a warning means for detection of an external force exceeding a preset allowable value. I do.

The external force detecting means includes, for example, an optical system for detecting the displacement of the piezoelectric scanner, and specifies the external force applied to the piezoelectric scanner based on the correlation between the external force applied to the piezoelectric scanner and the displacement generated thereby. I do.

Alternatively, the external force detecting means includes means for detecting a voltage generated at the electrode of the piezoelectric scanner, and applies an external force to the piezoelectric scanner based on a correlation between the external force applied to the piezoelectric scanner and the voltage generated at the electrode. Identify external forces.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. First, a first embodiment will be described with reference to FIG. The present embodiment has a configuration in which a scanner breakage prevention mechanism is added to a scanning probe microscope having a linear correction mechanism disclosed in Japanese Patent Application Laid-Open No. 7-98206 by the applicant.

As shown in FIG. 1, a tube-type piezoelectric scanner (hereinafter, referred to as a scanner) 1 has a single common electrode provided on an inner peripheral surface of a tube-shaped piezoelectric body and an outer peripheral surface provided with a single common electrode. It has a configuration in which four drive electrodes are provided in the circumferential direction, one end of which is fixed on the fixed base 2.
An external force is applied to the scanner 1 based on this configuration, and the scanner 1 is displaced. A stage 3 is fixed to the other end of the scanner 1. A mirror 4 is fixed on the back side of the stage 3. An opening 2a is provided in the fixed base 2 around the center axis of the scanner 1, and light can be guided into the scanner from below.

Below the opening 2a, a quarter-wave plate 5, a polarizing beam splitter 6, and a lens 7 are arranged in this order from above. The polarization beam splitter 6 reflects light of a component having a specific vibration surface of the light emitted from the light source 8 toward the scanner 1. In addition, the polarizing beam splitter 6
The light reflected by the mirror 4 and returned is guided to the lens 7.

The lens 7 converts the incident light into convergent light and guides it to a position detector 9 disposed further below. This lens 7 is supported by a lens holder 10. As described above, the external force applied to the scanner 1 is detected based on the configuration for guiding the light from the light source 8 to the position detector 9 (external force detecting means).

The light source 8 includes a semiconductor laser 8a and a lens 8b. The light emitted from the semiconductor laser 8a is converted into parallel light by a lens 8b, and the parallel light is incident on the polarization beam splitter 6.

The position detector 9 is arranged such that the light receiving surface is located at the focal plane of the lens 7, and a spot is formed on the light receiving surface by the light arriving via the polarization beam splitter 6. Then, the position detector 9 detects the position of this spot.

The lens holder 10 has a thread 10 on its outer surface.
The screw 10a is screwed to the fixed base 2 by engaging with the screw thread 2b formed on the inner surface of the fixed base 2. At the lower end of the lens holder 10, a plurality of holes 10b are formed, into which a plurality of couplings 12a protruding from the gear 12 are inserted.

The gear 12 is rotatably supported.
The gear 12 meshes with a gear 14 fixed to a rotation shaft of a motor 13. The scan controller 15 performs a predetermined process on the reference voltage in the X direction generated by the waveform generator 16 and the reference voltage in the Y direction generated by the waveform generator 17, and controls each of the X direction and the Y direction. Generate a signal. These control signals in the X and Y directions are supplied to the scanner driver 18.

The scanner driver 18 applies voltages to four drive electrodes of the scanner 1 so as to displace the scanner 1 to a state specified by the supplied control signal.
The preamplifier 19 amplifies the output signal of the position detector 9 indicating the position of the spot and supplies the amplified signal to the arithmetic circuit 20. The arithmetic circuit 20 receives the output signal of the position detector 9 after being amplified by the preamplifier 19, determines the displacement state of the scanner 1 based on the output signal, and sends the displacement signal indicating the displacement state to the scan controller 15 and the controller 21. Supply.

The scan controller 15 includes the arithmetic circuit 2
It has a non-linearity correcting means 15a for applying a predetermined correction to a control signal generated based on the displacement signal supplied from 0.

The controller 21 and the warning means 22 connected thereto constitute a scanner damage prevention mechanism.
The warning unit 22 is configured by, for example, a buzzer that emits a sound as schematically illustrated in the drawing, but may be configured by a red lamp that emits light such as red light.

Next, the operation of the scanner system configured as described above will be described. First, when the scanner driver 18 does not apply a voltage to any of the four drive electrodes of the scanner 1, the scanner 1 is not displaced and is in the reference state. When the scanner driver 18 applies a voltage to the four drive electrodes of the scanner 1 based on a control signal output from the scan controller 15, displacement occurs in the scanner 1 according to the state of the voltage application.

The light collimated by the lens 8 b of the light source 8 is reflected by the polarizing beam splitter 6. At this time, the light becomes linearly polarized light having a polarization component in only one direction by the polarizing beam splitter 6, and further becomes circularly polarized light by transmitting through the quarter-wave plate 5. And 1 /
The light transmitted through the four-wavelength plate 5 enters the inside of the scanner 1 from the opening 2 a of the fixed base 2. The light that has entered the inside of the scanner 1 reaches the mirror 4, is reflected by the mirror 4, and enters the １ ／ wavelength plate 5 again. When the light passes through the quarter-wave plate 5, it becomes linearly polarized light that is orthogonal to the polarization at the beginning. Thus, in the polarization beam splitter 6, the light passes through the light source 8 without being reflected. The light transmitted through the polarizing beam splitter 6 is condensed by the lens 7 and enters the position detector 9 to form a spot on the light receiving surface of the position detector 9.

Here, when the scanner 1 is not displaced,
The spot is formed at the center of the light receiving surface of the position detector 9. On the other hand, when the scanner 1 is displaced, the mirror 4 is inclined with respect to the optical axis of the light incident on the inside of the scanner 1. Therefore, the light is reflected by the mirror 4 in a direction different from the incident direction. Specifically, when the tip of the scanner 1 has an inclination of θ with respect to the reference state, the light incident on the mirror 4 is reflected at an angle of 2θ.

The light reflected by the mirror 4 is converted into linearly polarized light by the quarter-wave plate 5, and then passes through the polarization beam splitter 6 and the lens 7 while being condensed.
To form a spot on the light receiving surface of the position detector 9. However, since the light is reflected by the mirror 4 at an angle of 2θ, the spot formation position is shifted from the center of the position detector 9 according to the tilt direction of the mirror 4.

Here, the relation d = f · tan (2θ) (1) is established between the deviation amount d of the spot formation position on the position detector 9 and the inclination angle θ of the mirror 4. Therefore, by detecting the deviation amount d of the spot formation position by the position detector 9, the inclination angle θ of the mirror 4 can be obtained based on the above equation (1).

The arithmetic circuit 20 performs the above arithmetic based on the output signal of the position detector 9 to obtain
The tilt angle θ of the mirror 4 is obtained. Also position detector 9
For example, the light receiving area is divided into four parts, and the spot shift direction can be detected based on which area the spot is formed. The displacement direction of the spot is mirror 4
Accordingly, the arithmetic circuit 20 determines the tilt direction of the mirror 4 based on the output signal of the position detector 9. Thus, the arithmetic circuit 20 specifies the tilt angle θ and the tilt direction of the mirror 4, that is, the tilt angle θ and the tilt direction of the stage 3, and detects the state of the stage 3.

The arithmetic circuit 20 converts the information thus obtained into monitor signals representing the displacements of the stage 3 in the X and Y directions, respectively, and outputs the signals to the scan controller 15.
Give to. Specifically, assuming that light receiving information in each of the four light receiving regions of the position detector 9 is A, B, C, and D, dx = (A + D)-(B + C) (2) dy = (A + B)-( C + D) (3) The monitor signals dx and dy are obtained based on the following equation, and are supplied to the scan controller 15.

The scan controller 15 generates respective control signals in the X and Y directions to displace the stage 3 to a predetermined state based on the reference waveforms output from the waveform generators 16 and 17, respectively. In this state, the nonlinearity control means 15a monitors the monitor signal,
The deviation between the currently desired state of the stage 3 and the actual state of the stage 3 indicated by the monitor signal is obtained. Between the desired stage 3 state and the actual stage 3 state,
Since deviation occurs due to hysteresis, creep, or the like generated in the displacement of the piezoelectric body constituting the scanner 1, the non-linearity control means 15a calculates this deviation. Then, the nonlinearity control means 15a changes the control signal so as to compensate for this deviation. That is, feedback control is performed so that the actual state of the stage 3 obtained by the arithmetic circuit 20 becomes a desired state.

Thus, the actual state of the stage 3 (the tilt angle θ and the tilt direction) is optically detected, and the feedback control is performed so that the detected actual state of the stage 3 becomes a desired state. In addition, even if hysteresis or creep occurs in the displacement of the piezoelectric body constituting the scanner 1, it is prevented from affecting the displacement of the stage 3, and the state of the stage 3 can be controlled well.

Next, the operation of the scanner damage prevention mechanism will be described. FIG. 2A schematically shows how the scanner is displaced when a load is applied to the scanner in a lateral direction, and FIG. 2B shows the relationship between the load applied to the scanner and the displacement caused thereby. It is a graph.

As can be seen from FIG. 2B, the external force (load) applied to the tip of the scanner and the displacement of the tip of the scanner have a linear relationship, and as is generally well known, the displacement of the scanner and the displacement of the scanner are generally known. The slope also has a linear relationship. Therefore, the external force applied to the scanner can be obtained from the inclination of the scanner.

The controller 21 checks the inclination angle θ of the stage 3 obtained by the arithmetic circuit 20, ie, the displacement of the scanner 1, and if this exceeds a predetermined value (allowable value), a buzzer as a warning means. By driving 104, a warning sound is generated.

The predetermined value (allowable value) is determined according to the mechanical strength of the scanner 1, and different values are usually selected in the xy and z directions. As described above, when an excessive external force in the radical direction is applied to the scanner 1, a warning sound is issued, so that a situation in which the excessive external force is continuously applied to damage the scanner 1 is avoided.

Further, in order to prevent the scanner 1 from being damaged, it is preferable to perform the following processing. It is effective that the controller 21 drives the buzzer 104 as a warning unit and outputs a stop signal to stop the operation of the scanner 1 to the scan controller 15.

Alternatively, the scan controller 15
In order to set the scanner 1 in the reference state based on the stop signal, the scanner driver 18
, The voltage applied to the drive electrode of the scanner 1 may be cut off.

Further, the controller 21 includes an arithmetic circuit 2
0, the displacement of the scanner 1 is monitored, and the scanner 1 is sent from the scanner driver 18 via the scan controller 15 so as to be equal to or less than a predetermined value (allowable value) set in advance.
May be feedback controlled.

The apparatus shown in FIG. 1 is a sample scanning type scanning probe microscope, but the above-described scanner damage prevention mechanism can be applied to a probe scanning type scanning probe microscope as it is.

Next, a second embodiment will be described with reference to FIG. FIG. 3 shows a probe scanning type scanning probe microscope provided with a scanner breakage prevention mechanism according to the present embodiment.

As shown in FIG. 3, the cantilever tip 110 extends from the cantilever 11
4 has a probe 116 at its tip. The cantilever tip 110 is held by a lever holder 118.

The lever holder 118 has a holder main body 120 in which a concave portion 122 for accommodating the support portion 112 of the cantilever chip 110 is formed. The support body 112 of the cantilever chip 110 is provided on the holder body 120.
Is fixed by a screw 126.

The head 138 to which the lever holder 118 is attached is a scanner 16 fixed to a base 158 supported by a Z stage 170 so as to be movable in the z direction.
0 is fixed to the free end. The scanner 160 is
The head 138 is displaced in the xyz directions according to a voltage supplied from a scanner driver (not shown), and as a result, the head 138 is scanned in the xyz directions.

The head 138 has a head body 140 in which a concave portion for receiving the lever holder 118 is formed. The lever holder 118 is positioned by the holder main body 120 being brought into contact with the corner of the concave portion. It is supported by the magnetic force of the embedded magnet 144.

The head 138 is connected to the cantilever 11.
4 has a displacement detecting optical system by an optical lever method for optically detecting the displacement of the free end. This optical system includes a laser module 152 that irradiates a free end of the cantilever 114 with a convergent beam, and a four-division photodiode 154 that receives light reflected at the free end of the cantilever 114.

Below the head 138, an XY stage 172 on which the sample 174 is mounted is arranged. The XY stage 172 moves the sample 174 to the head 138 in order to change the measurement position by the probe 116 and when exchanging the sample.
Used to keep away from.

The head body 140, the holder body 120, and the cantilever chip 110 are machined with high precision. The xy position of the cantilever unit 110 with respect to the lever holder 118 is adjusted in advance. The adjusted lever holder 118 is positioned by pressing the three reference surfaces defining the corners of the holder body 120 against the three abutment surfaces defining the corners of the recess formed in the head body 140, and is positioned with respect to the head 138. To be installed in a fixed position. Since the xy position of the cantilever unit 110 is adjusted in advance, the lever holder 118
Is attached to the head 138, the free end of the cantilever 114 is automatically positioned at the focal position of the light emitted from the laser module 152.

At the time of SPM measurement, the head 138 is moved by the scanner 160 and the probe 116 is moved with respect to the sample.
Is scanned in the xy directions. During scanning, cantilever 114
Monitor the displacement of the free end of the. As described above, the displacement of the free end of the cantilever 114, that is, the z position of the probe 116 can be determined by monitoring the position of the spot formed on the photodiode 154 by the light emitted from the laser module 152 being reflected by the cantilever 114. By performing image processing based on the xy position obtained with respect to the scanner 160 and the z position obtained with respect to the photodiode 154, an SPM image of the sample is obtained.

Next, the scanner damage prevention mechanism of this embodiment will be described. The scanner damage prevention mechanism of this embodiment includes an x-voltmeter 176 connected to the x-direction drive electrode of the scanner 160, a y-voltmeter 178 connected to the y-direction drive electrode of the scanner 160, and the controller 18
0. The controller 180 includes the x voltmeter 1
Based on the information from the voltmeter 76 and the y voltmeter 178, the driving of the warning means 182 for calling attention to the operator is controlled,
A Z stage driver 184 for controlling the driving of the Z stage 170 and an XY stage driver 186 for controlling the driving of the XY stage 172 are controlled.

The x voltmeter 176, the y voltmeter 178, and the controller 180 constitute an external force detecting means, which specifies the magnitude and direction of the external force applied to the scanner 1 based on the voltage detected here, and responds to the external force. Warning means 18
2 is driven.

The warning means 182 is, for example, a buzzer that emits a sound as schematically illustrated in the drawing, but may be a red lamp that emits light such as red light. Warning means 1
Reference numeral 82 denotes any functional body that can perform an operation that draws the operator's attention.

Next, the operation of the scanner damage prevention mechanism configured as described above will be described. As shown in FIG. 4, the scanner 160 includes a cylindrical piezoelectric body 162,
One common electrode 164 circling the inner peripheral surface and four drive electrodes 166 located at intervals in the circumferential direction of the outer peripheral surface
a, 168a, 166b, and 168b.

The inner common electrode 164 is grounded, and the + x-side drive electrode 166 for displacement in the x direction, which is located axially symmetrically with respect to each other.
A + x voltmeter 1 is applied to each of the a and -x side drive electrodes 166b.
76a and the -x voltmeter 176b are connected, and similarly, the + y-side drive electrode 16 for displacement in the y direction, which is located axially symmetrically with respect to each other.
A + y voltmeter 178a and a -y voltmeter 178b are connected to the 8a and -y drive electrodes 168b, respectively. In addition, the x voltmeter 176 in FIG.
And -x voltmeter 176b are representatively shown, and y voltmeter 178 is typically + y voltmeter 178a and -y voltmeter 17
8b is shown.

FIG. 5A schematically shows a state where a force Fx in the −x direction is applied to the scanner 160.
(B) is a graph showing the result of measuring the magnitude of the force F-x and the voltage Vx generated at the + x-side drive electrode 166a at this time.

As shown in FIG. 5B, the scanner 1
There is a specific relationship between the force applied to 60 and the voltage generated at the drive electrode. Therefore, by examining the voltage generated at each of the four drive electrodes, the force F applied to the scanner 160 is determined.
Size and direction can be specified. Not only the force in the x direction or the y direction but also the force in the z direction can be specified.

In FIG. 4, the + x-side drive electrode 166a, the -x-side drive electrode 166b, the + y-side drive electrode 168a, and-
The voltage generated at the y-side drive electrode 168b is +
x voltmeter 176a, -x voltmeter 176b, and + y voltmeter 1
78a and -y voltmeter 178b are detected and the information is sent to controller 180.

In FIG. 3, the controller 180 determines that x
The magnitude and direction of the force applied to the scanner 160 are specified based on the information supplied from the voltmeter 176 and the y voltmeter 178, and when the force exceeds the preset allowable value, the warning unit 182 is driven. , A command to stop the Z stage 170 is given to the Z stage driver 184, and a command to stop the XY stage 172 is given to the XY stage driver 186.
Put out The allowable value is determined according to the mechanical strength of the scanner 160, and usually different values are selected in the xy direction and the z direction.

Thus, in a situation where the operator is applying force to the scanner 160 when the cantilever chip 110 is replaced, the function of alerting the operator by the warning means 182 contributes to preventing the scanner 160 from being damaged. Also,
In a situation where an axial force is applied to the scanner 160 due to a malfunction of the approach, the function of stopping the Z stage 170 contributes to preventing the scanner 160 from being damaged. Further, in a situation where the XY stage 172 is in contact with the head 138 that has been lowered too much, the function of stopping the XY stage 172 contributes to preventing the scanner 160 from being damaged.

Therefore, the following can be said about the scanning probe microscope in the present embodiment. (1) In a scanning probe microscope that performs relative scanning between a probe and a sample by using a piezoelectric scanner, a moving means for relatively moving the probe and the sample (in the second embodiment, Are the XY stage 172 and the Z stage 170) and external force detecting means for detecting an external force applied to the piezoelectric scanner (in the second embodiment,
x voltmeter 176, y voltmeter 178, controller 180
The external force detection means includes a scanner damage prevention mechanism that drives the warning means for detection of an external force exceeding a preset allowable value. Scanning probe microscope. (2) In the scanning probe microscope according to the above (1), the external force detecting means drives a warning means and stops the moving means, and further includes a scanner damage preventing mechanism. (3) In the above (1) or (2), the external force detecting means includes a means for detecting a voltage generated at the electrode of the piezoelectric scanner, and a correlation between the external force applied to the piezoelectric scanner and the voltage generated at the electrode. A scanning probe microscope having a scanner breakage prevention mechanism for identifying an external force applied to a piezoelectric body scanner based on a relationship.

The present invention is not limited to the above-described embodiment at all, and various modifications can be made without departing from the gist of the present invention. For example, in the embodiment, the cylindrical piezoelectric scanner is described as an example, but the scanner breakage prevention mechanism of the present invention can be applied to a stacked type or another type of piezoelectric scanner.

[0064]

According to the scanning probe microscope of the present invention, when excessive force is applied to the piezoelectric scanner, the operator is alerted by sound, light, or the like. The frequency of scanner damage is reduced.

[Brief description of the drawings]

FIG. 1 shows a scanner system of a sample scanning type scanning probe microscope provided with a scanner breakage prevention mechanism according to a first embodiment of the present invention, with a part cut away.

FIG. 2A schematically shows a state where the scanner is displaced when a load is applied to the scanner in a lateral direction,
(B) is a graph showing the relationship between the load applied to the scanner and the displacement caused by the load.

FIG. 3 is a partially cut-away view of a probe-scanning scanning probe microscope provided with a scanner breakage prevention mechanism according to the first embodiment of the present invention.

FIG. 4 shows details of the scanner, the x-voltmeter, and the y-voltmeter shown in FIG.

FIG. 5A is a diagram schematically illustrating a state in which a lateral force is applied to a scanner, and FIG. 5B is a graph illustrating a relationship between a force applied to the scanner and a voltage generated at an electrode.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Scanner 3 Stage 4 Mirror 5 1/4 wavelength plate 6 Polarization beam splitter 7 Lens 8 Light source 9 Position detector 20 Arithmetic circuit 21 Controller 22 Warning means

Claims (3)

[Claims] 1. A scanning probe microscope for performing relative scanning between a probe and a sample using a piezoelectric scanner, an external force detecting means for detecting an external force applied to the piezoelectric scanner, and a warning means for calling attention of an operator. A scanning probe microscope provided with a scanner breakage prevention mechanism, wherein the external force detection means drives a warning means for detection of an external force exceeding a preset allowable value. 2. An external force detecting means according to claim 1, wherein said external force detecting means includes an optical system for detecting a displacement of said piezoelectric scanner. A scanning probe microscope equipped with a scanner breakage prevention mechanism that identifies the applied external force. 3. The external force detecting means according to claim 1, wherein the external force detecting means includes means for detecting a voltage generated at an electrode of the piezoelectric scanner, and based on a correlation between an external force applied to the piezoelectric scanner and a voltage generated at the electrode. A scanning probe microscope equipped with a scanner breakage prevention mechanism that identifies an external force applied to a piezoelectric scanner.