Scanning probe microscope

Abstract

This invention provides a scanning probe microscope that contacts a sample surface with a probe and intermittently scans the sample surface using the probe. The microscope comprises: a cantilever with the probe at its front end; a drive unit that performs a separation action to separate the sample and the probe from the state where the probe is in contact with the sample surface; an excitation unit that causes the sample and the cantilever to vibrate relative to each other at a predetermined frequency during the separation action; a determination unit that determines the separation of the probe relative to the sample surface based on the change in amplitude of the cantilever at the predetermined frequency in the flexural or torsional direction during the separation action; and a drive control unit that stops the separation action of the drive unit at the moment when the determination unit determines that separation has occurred, and moves the probe and the sample surface relative to each other to the next measurement point on the sample.

Description

[0001] The present application is a divisional application of the application with the title of "Scanning Probe Microscope and Scanning Method Thereof", the application number of 201810182105.1, the filing date of March 6, 2018, and the application number of 202110422491.9. TECHNICAL FIELD

[0002] The present application relates to a scanning probe microscope and a scanning method thereof. BACKGROUND

[0003] In the past, a scanning probe microscope in which a probe formed at the front end of a cantilever is continuously scanned on the surface of a sample while the interaction (for example, the amplitude of the cantilever or the deflection of the cantilever) between the probe and the sample is constantly maintained, thereby measuring the convex-concave shape of the sample surface, is known (see Patent Document 1). However, in the scanning probe microscope described in Patent Document 1, since the probe and the sample are always in contact, there is a possibility that the probe is worn or the sample is damaged.

[0004] On the other hand, in Patent Documents 2 and 3, an intermittent measurement method in which the probe is brought into contact with the sample surface only at predetermined measurement points on the surface of the sample and intermittently scans the surface of the sample, thereby measuring the convex-concave shape of the sample surface, is proposed. In this intermittent measurement method, the probe is brought close to the sample surface from above the predetermined measurement points, and the height of the probe when the probe comes into contact with the sample surface is measured. Then, when the measurement is completed, the probe in contact with the sample surface is separated from the sample surface by a predetermined "separation distance" and moved to above the next measurement point. In this way, in the above-described intermittent measurement method, the probe and the sample surface are in contact only at the measurement points, and therefore the minimum contact is sufficient, and it is possible to reduce the wear of the probe or the damage to the sample, as compared with Patent Document 1.

[0005] In particular, in the case of performing the intermittent measurement method in the so-called contact mode in which the deflection of the cantilever is controlled so as to be constantly maintained, the scanning probe microscope generally intermittently scans the surface of the sample by repeatedly performing the process of bringing the probe close to the sample surface, judging that the probe is in contact when the force (deflection) applied to the cantilever is a certain value or more, and measuring the height of the probe, and the process of moving the probe to above the next measurement position by separating the probe and the sample by the above-described "separation distance".

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 10-62158

[0007] Patent Document 2: Japanese Patent Application Laid-Open No. 2001-33373

[0008] Patent Document 3: Japanese Patent Application Laid-Open No. 2007-85764

[0009] Here, the above-described "separation distance" is set so that the force calculated by the product of the spring constant of the cantilever and the separation distance is larger than the attractive force between the probe and the sample in order to separate the probe from the sample. However, the attractive force between the probe and the sample varies depending on each position of the sample surface. Therefore, in the case of a sample in which the attractive force between the probe and the sample greatly differs depending on the position of the sample surface, the separation distance is set to a large value having a sufficient margin even at the position of the maximum attractive force so that the probe can be reliably separated. Also, the value is considered in the case where the probe does not come into contact with the protrusions of the sample during the movement in the air after the probe is separated from a certain measurement point, and thus the value having a margin is set as the separation distance by the operators based on experience. Therefore, the probe and the sample come into contact with each other and are damaged due to the insufficient separation distance caused by the presence of a larger attractive force than predicted or a higher protrusion.

[0010] However, if the separation distance is set to a large value having a sufficient margin, the movement path until the next measurement point in the air becomes long. As a result, the entire time for measuring the protrusions and depressions of the sample surface becomes long, and the measurement efficiency of the protrusions and depressions of the sample surface is reduced. SUMMARY

[0011] The present application has been made in view of such circumstances, and it is an object to provide a scanning probe microscope and a scanning method thereof capable of improving the measurement efficiency of the protrusions and depressions of a sample surface.

[0012] One embodiment of the present application is a scanning probe microscope which brings a probe into contact with a sample surface and intermittently scans the sample surface with the probe, and includes a cantilever having the probe at a distal end thereof, a driving section which performs a separation operation of separating the sample and the probe from a state where the probe is in contact with the sample surface, a vibration exciting section which relatively vibrates the sample and the cantilever at a predetermined frequency in the separation operation, a determination section which determines detachment of the probe from the sample surface based on a change in amplitude of the predetermined frequency of the cantilever in a flexural direction or a torsional direction in the separation operation, and a driving control section which stops the separation operation of the driving section at the time when detachment is determined by the determination section and relatively moves the probe and the sample surface to a next measurement point of the sample.

[0013] One embodiment of the present application is the above-described scanning probe microscope, in which the predetermined frequency is a non-resonant frequency of the cantilever, and the determination section determines that the probe is detached from the sample surface when a decrease in amplitude of the non-resonant frequency of the cantilever in the flexural direction or the torsional direction in the separation operation exceeds a predetermined value.

[0014] One embodiment of the present application is the scanning probe microscope described above, in which the prescribed frequency is a resonance frequency of the cantilever in a state in which the cantilever is in contact with the sample, and the determination section determines that the probe is separated from the sample surface when the amount of decrease in the amplitude of the cantilever in the flexure direction or the torsion direction exceeds a prescribed value in the separation operation.

[0015] One embodiment of the present application is the scanning probe microscope described above, in which the prescribed frequency is a resonance frequency of the cantilever, and the determination section determines that the probe is separated from the sample surface when the amount of increase in the amplitude of the cantilever in the flexure direction or the torsion direction at the resonance frequency exceeds a prescribed value in the separation operation.

[0016] As described above, according to the present application, the troublesome setting of the separation distance taking into account the unknown adsorption force or the height of the convex portion of the sample surface and the damage to the probe and the sample can be eliminated, and thus the efficiency of measurement of the convex-concave shape of the sample surface can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a view showing an example of the schematic structure of the scanning probe microscope A of the first embodiment.

[0018] Figure 2 is a perspective view of the sample S having a slope and the cantilever 2 of the first embodiment.

[0019] Figure 3 is a view showing the flow of the intermittent measurement method of the scanning probe microscope A of the first embodiment.

[0020] Figure 4 is a view for explaining the first range and the second range of the first embodiment.

[0021] Figure 5 is a view showing the state of the cantilever 2 in the case where the sample S is caused to operate in the direction away from the probe 2a at a normal speed.

[0022] Figure 6 is a view showing the state of the cantilever 2 in the separation operation of the first embodiment (in the case where the sample S is caused to operate in the direction away from the probe 2a at a speed exceeding the response speed of the cantilever 2).

[0023] Figure 7 is a flowchart of the separation determination process of the first embodiment.

[0024] Figure 8 is a view showing an example of the schematic structure of the Z-direction driving device 51 of the first embodiment.

[0025] Figure 9 is a graph showing an example of the schematic structure of the scanning probe microscope B of the second embodiment.

[0026] Figure 10 is a graph showing a change in the speed of the cantilever 2 in the flexure direction in the separation operation of the second embodiment.

[0027] Figure 11 is a graph showing the case of the cantilever 2 in the separation operation of the second embodiment (in the case where the sample S is operated in the direction of separation from the probe 2a at a speed slower than the response speed of the cantilever 2).

[0028] Figure 12 is a flowchart of the separation determination processing of the second embodiment.

[0029] Figure 13 is a graph showing an example of the schematic structure of the scanning probe microscope C of the third embodiment.

[0030] Figure 14 is a graph showing the case of the cantilever 2 in the separation operation of the third embodiment Figure 14 (a) of FIG. 7 shows the case of vibration in the flexure direction, Figure 14 (b) of FIG. 7 shows the case of vibration in the twist direction).

[0031] Figure 15 is a graph showing an example of the schematic structure of the scanning probe microscope D of the fourth embodiment.

[0032] Figure 16 is a graph explaining a method of detecting the amount of decrease in the amplitude of the cantilever of the fourth embodiment in vibration in the flexure direction or the twist direction at the non-resonant frequency Figure 16 (a) of FIG. 8 shows the case of vibration in the flexure direction, Figure 16 (b) of FIG. 8 shows the case of vibration in the twist direction).

[0033] Figure 17 is a graph explaining a method of detecting the amount of increase in the amplitude of the cantilever of the fourth embodiment in vibration in the flexure direction or the twist direction at the resonant frequency Figure 17 (a) of FIG. 9 shows the case of vibration in the flexure direction, Figure 17 (b) of FIG. 9 shows the case of vibration in the twist direction).

[0034] Figure 18 is a graph explaining a method of detecting the amount of decrease in the amplitude of the cantilever of the fourth embodiment in vibration in the flexure direction or the twist direction at the resonant frequency Figure 18 (a) of FIG. 10 shows the case of vibration in the flexure direction, Figure 18 (b) of FIG. 10 shows the case of vibration in the twist direction).

[0035] Figure 19 Fig. 1 is a diagram showing an example of an outline structure of a scanning probe microscope E according to a fifth embodiment.

[0036] Figure 20 Fig. 4 is a diagram for explaining a separation determination process according to the fifth embodiment.

[0037] Explanation of Reference Numerals

[0038] 1: scanning probe microscope; 2: cantilever; 3: excitation section; 5: movement driving section; 6: displacement detecting section; 7: control device; 42: determination section; 43: driving control section; 44: measurement section; 51: Z-direction driving device (driving section); 52: XY scanner (scanner section). DETAILED DESCRIPTION

[0039] The scanning probe microscope according to one embodiment of the present application is a scanning probe microscope using a so-called intermittent measurement method in which a probe is brought into contact with a sample surface and the sample surface is intermittently scanned by the probe.

[0040] Hereinafter, a scanning probe microscope according to one embodiment of the present application will be described using the drawings. In the drawings, the same or similar parts are denoted by the same reference numerals, and repetitive description will be omitted at times. In addition, the shape, size, and the like of the elements in the drawings are sometimes exaggerated for the sake of more clear description.

[0041] (First Embodiment)

[0042] Figure 1 Fig. 1 is a diagram showing an example of an outline structure of a scanning probe microscope A according to the first embodiment. As shown in Fig. 1, the scanning probe microscope A has a cantilever 2, a sample stage 4, a movement driving section 5, a displacement detecting section 6, and a control device 7. Figure 1

[0043] The cantilever 2 has a probe 2a at the tip end. The base end of the cantilever 2 is fixed, and the tip end is a free end. The cantilever 2 is an elastic rod member having a small spring constant K, and when the probe 2a at the tip end comes into contact with the surface of a sample S (hereinafter referred to as "sample surface"), a deflection corresponding to the pressure bonding force with which the probe 2a at the tip end presses the sample surface is generated.

[0044] In addition, in the case where the probe 2a at the tip end of the cantilever 2 is in contact with the sample surface and in the case where there is an inclination in the sample surface, a twist or a deflection corresponding to the inclination of the sample surface and the fulcrum reaction force of the fulcrum, which is the contact point between the probe 2a at the tip end and the sample surface, is generated.

[0045] ​The movement driving section 5 relatively moves the probe 2a and the sample S with respect to three-dimensional directions. The movement driving section 5 has a Z-direction driving device 51 (driving section) and an XY scanner 52 (scanner section).

[0046] The sample stage 4 is placed on the Z-direction driving device 51. The sample S is placed on the sample stage 4 in a manner to be opposed to the probe 2a of the cantilever 2.

[0047] The Z-direction driving device 51 moves the sample stage 4 in a direction (Z-direction) perpendicular to a horizontal plane. For example, the Z-direction driving device 51 is a piezoelectric element.

[0048] The Z-direction driving device 51 moves the sample stage 4 in the Z-direction according to a control from the control device 7, thereby performing an approach operation of bringing the sample surface close to the probe 2a or a separation operation of moving the sample S in a direction to separate from the probe 2a.

[0049] The XY scanner 52 relatively moves the probe 2a and the sample S with respect to XY directions according to a control from the control device 7. In addition, in the Figure 1 The plane parallel to the surface of the sample stage 4 is a horizontal plane, and here, 2 axes X, Y orthogonal thereto are defined as an XY plane. For example, the XY scanner 52 is a piezoelectric element.

[0050] In addition, the Z-direction driving device 51 and the XY scanner 52 are not particularly limited as to the arrangement relationship as long as they are configured to relatively perform scanning for three-dimensional shape observation.

[0051] The displacement detecting section 6 detects the deflection amount and the twist amount of the cantilever 2. In the first embodiment, a case where the displacement detecting section 6 uses an optical lever method to detect the deflection amount and the twist amount of the cantilever 2 will be described.

[0052] The displacement detecting section 6 has a light irradiation section 61 and a light detecting section 62.

[0053] The light irradiation section 61 irradiates laser light L1 against a not-shown reflecting surface formed on the back surface of the cantilever 2.

[0054] The light detecting section 62 receives laser light L2 reflected by the above-described reflecting surface. The light detecting section 62 is a light detector having 4-divided light receiving surfaces 27 that receive the laser light L2 reflected by the back surface. That is, the optical path (typically, around the center of the light receiving surface 27) is adjusted so that the laser light L2 reflected by the back surface of the cantilever 2 is incident on the 4-divided light receiving surfaces 27 of the light detecting section 62.

[0055] Next, the method of detecting the deflection amount and the twist amount of the cantilever 2 of the first embodiment will be described using Figure 1 and Figure 2 Next, the method of detecting the deflection amount and the twist amount of the cantilever 2 of the first embodiment will be described using Figure 2is a perspective view of the specimen S having a slope and the cantilever 2.

[0056] The cantilever 2 is displaced in either or both of the Z direction and the Y direction with the probe 2a in contact with the specimen surface. In the first embodiment, the displacement of the cantilever 2 in the Z direction is referred to as a deflection amount, and the displacement of the cantilever 2 in the Y direction is referred to as a twist amount. For example, in an initial condition, the position of the incident point in the light-receiving surface 27 of the light detector 62 of the reflected laser light L2 in a state where no force is applied to the probe 2a is taken as the center position of the light-receiving surface 27. In addition, the state where no force is applied to the probe 2a refers to a state where the cantilever is not deformed, for example, with the probe 2a not in contact with the specimen surface (hereinafter referred to as a "free state").

[0057] In the contact mode, when the probe 2a is in contact with the specimen surface, a deflection amount or a twist amount is generated on the cantilever 2 by applying a force to the probe 2a. Therefore, the position of the reflection point of the reflected laser light L2 from the back surface of the cantilever 2 on which the deflection amount or the twist amount is generated is displaced from the center position. Therefore, the scanning probe microscope A can detect the magnitude and the direction of the force applied to the probe 2a by capturing the moving direction of the point position in the light-receiving surface 27 of the light detector 62.

[0058] For example, in the case where the twist amount is generated on the cantilever 2, the change in the point position in the α direction can be captured in the light-receiving surface 27 of the light detector 62. In addition, in the case where the deflection amount is generated on the cantilever 2, the change in the point position in the β direction can be captured in the light-receiving surface 27. Figure 1

[0059] Here, the amount of change in the point position from the center position depends on the twist amount or the deflection amount. Specifically, in the case where the cantilever 2 is deflected in the +Z direction, the reflection point of the laser light L2 in the light-receiving surface 27 of the light detector 62 changes in the +β direction. In addition, in the case where the cantilever 2 is deflected in the -Z direction, the reflection point of the laser light L2 in the light-receiving surface 27 of the light detector 62 changes in the -β direction. On the other hand, in the case where the twist amount is generated on the cantilever 2 in the +Y direction, the reflection point of the laser light L2 in the light-receiving surface 27 of the light detector 62 changes in the +α direction. In addition, in the case where the twist amount is generated on the cantilever 2 in the -Y direction, the reflection point of the laser light L2 in the light-receiving surface 27 of the light detector 62 changes in the -α direction.

[0060] ​The light detection section 62 outputs a first detection signal corresponding to the position of the reflection point of the laser L2 in the ±Z direction of the light receiving surface 27 to the control device 7. That is, the first detection signal is a DIF signal (deflection signal) corresponding to the deflection amount of the cantilever 2. In addition, the light detection section 62 outputs a second detection signal corresponding to the position of the reflection point of the laser L2 in the ±Y direction of the light receiving surface 27 to the control device 7. That is, the second detection signal is a FFM signal (twist signal) corresponding to the twist amount of the cantilever 2.

[0061] Next, the control device 7 of the first embodiment will be described.

[0062] As shown in FIG. 4, the control device 7 has a determination section 42, a drive control section 43, and a measurement section 44. Figure 1

[0063] The determination section 42 determines whether the probe 2a is in contact with the sample surface on the basis of the first detection signal and the second detection signal output from the light detection section 62. In the following description, the process of determining whether the probe 2a is in contact with the sample surface will be referred to as a "contact determination process".

[0064] In addition, the determination section 42 determines whether the probe 2a is separated from the sample surface on the basis of the first detection signal and the second detection signal output from the light detection section 62. In the following description, the process of determining whether the probe 2a is separated from the sample surface will be referred to as a "separation determination process".

[0065] The drive control section 43 controls the relative movement amount of the probe 2a with respect to the sample S by moving the drive section 5. Here, the scanning probe microscope A of one embodiment of the present application uses an intermittent measurement method of bringing the probe 2a into contact with the sample surface only at a plurality of measurement points set in advance on the sample surface, thereby intermittently scanning the sample surface. Therefore, the drive control section 43 controls each of the approach operation of bringing the probe 2a close to a measurement position, the separation operation of separating the probe 2a and the sample S, and the empty movement operation of moving the probe 2a to the next measurement position.

[0066] Specifically, the drive control section 43 outputs a contact operation signal to the Z direction drive device 51 in order to bring the probe 2a into contact with the sample surface, thereby raising the sample S. Thus, the drive control section 43 brings the probe 2a and the sample surface close to each other.

[0067] The drive control section 43 stops the output of the contact operation signal to the Z direction drive device 51 in the case where it is determined by the contact determination process that the probe 2a is in contact with the sample surface, thereby stopping the approach operation of raising the sample S.

[0068] ​The drive control section 43 outputs a separation operation signal to the Z-direction drive device 51 in order to separate the sample surface from the probe 2a, and lowers the sample S. Thus, the drive control section 43 causes the sample surface to operate in a direction to separate from the probe 2a. That is, the drive control section 43 causes the sample surface to retreat from a state of contact with the probe 2a.

[0069] Here, one of the features of the first embodiment is that the drive control section 43 causes the sample S to operate in a direction to separate from the probe 2a at a speed exceeding the response speed of the cantilever 2 in the separation operation. Here, the response speed is an average moving speed calculated from the resonance frequency of the cantilever 2 and the amplitude at which the cantilever 2 can stably operate at the resonance frequency. Thus, the separation operation of the first embodiment is an operation of causing the sample S to operate in a direction to separate from the probe 2a at a speed exceeding the response speed of the cantilever 2 from a state of contact of the probe 2a with the sample surface.

[0070] The drive control section 43 stops the output of the separation operation signal to the Z-direction drive device 51 in a case where it is determined by the separation determination processing that the probe 2a is separated from the sample surface, and thereby stops the separation operation of lowering the sample S.

[0071] The drive control section 43 moves the probe 2a to a measurement lowering position located directly above the next measurement position by outputting a drive signal to the XY scanner 52.

[0072] The measurement section 44 measures the convex-concave shape of the sample surface in a state of contact of the probe 2a with the sample surface. For example, the measurement section 44 measures the distance of relative movement of the sample S with respect to the probe 2a in the approach operation (hereinafter simply referred to as "relative distance") in a case where it is determined by the contact determination processing that the probe 2a is in contact with the sample surface, and thereby measures the convex-concave shape of the sample surface. For example, the measurement section 44 can calculate the relative distance from the voltage value of the drive signal in a state of contact of the probe 2a with the sample surface. In addition, the measurement section 44 can directly measure the displacement of the sample stage 4 by a sensor (not shown), or can directly measure the height of the sample stage 4 by a sensor (not shown).

[0073] Next, the intermittent measurement method of the scanning probe microscope A of the first embodiment will be described with reference to FIG. 6. Figure 3 The flow of the intermittent measurement method of the scanning probe microscope A of the first embodiment will be described. In addition, as an initial condition, a case where the probe 2a is located at a measurement lowering position of a prescribed measurement point is adopted.

[0074] The drive control section 43 outputs a contact operation signal to the Z-direction drive device 51 to raise the sample stage 4, and thereby starts the approach operation of the probe 2a to the sample surface (step S101).

[0075] The determination section 42 performs contact determination processing of determining whether the probe 2a is in contact with the sample surface based on the first detection signal and the second detection signal output from the light detection section 62 in the case where the approach operation is started (step S102).

[0076] The determination section 42 stops the approach operation in the case where it is determined that the probe 2a is in contact with the sample surface by the contact determination processing (step S103). In this case, since the probe 2a is in contact with the sample surface, a twist or a flex of a certain amount or more occurs in the cantilever.

[0077] The measurement section 44 measures the relative distance in the case where it is determined that the probe 2a is in contact with the sample surface, thereby measuring the convex-concave shape of the sample surface (step S104).

[0078] The drive control section 43 starts a separation operation of moving the sample S in a direction away from the probe 2a at a speed exceeding the response speed of the cantilever 2 in the case where the measurement of the relative distance by the measurement section 44 is completed (step S105).

[0079] The determination section 42 performs separation determination processing of determining whether the probe 2a is separated from the sample surface based on the first detection signal and the second detection signal output from the detection section 33 in the case where the separation operation is started (step S106).

[0080] The drive control section 43 stops the separation operation in the case where it is determined that the probe 2a is separated from the sample surface by the separation determination processing (step S107). Then, the drive control section 43 moves the probe 2a to a measurement lowering position located directly above the next measurement position by outputting a drive signal to the XY scanner 52 (step S108). Then, the drive control section 43 lowers the cantilever 2 from the measurement lowering position, brings the probe 2a into contact at the next measurement position, and starts measurement of the relative distance again by the measurement section 44. In this way, the scanning probe microscope A performs the operations of steps S101 to S108 in correspondence with each measurement point of the sample S, thereby intermittently scanning the sample surface.

[0081] Next, the contact determination processing of the first embodiment will be described.

[0082] The determination section 42 determines that the probe 2a is in contact with the sample surface in the case where the amount of flex indicated by the first detection signal output from the light detection section 62 exceeds the first range.

[0083] The determination section 42 determines that the probe 2a is in contact with the sample surface in the case where the amount of twist indicated by the second detection signal output from the light detection section 62 exceeds the second range.

[0084] Thus, the determination unit 42 determines that the probe 2a is in contact with the sample surface if at least one of the following conditions is met: a first condition where the deflection amount indicated by the first detection signal output from the light detection unit 62 exceeds a first range, and a second condition where the torsion amount indicated by the second detection signal output from the light detection unit 62 exceeds a second range. Furthermore, although the above is an example of independently determining the first and second detection signals, the determination unit 42 can also sum the square of the first detection signal and the square of the second detection signal, and determine contact if the positive value of the square root of the sum is a certain value or higher, using a set value corresponding to the characteristics.

[0085] Next, use Figure 4 The first and second scopes in this embodiment will be described. For example... Figure 4 As shown, the first range is the range between the upper and lower deflection thresholds. The upper deflection threshold is the amount of deflection of the cantilever 2 in the +Z direction due to contact between the probe 2a and the surface of the sample S. On the other hand, the lower deflection threshold is the amount of deflection of the cantilever 2 in the -Z direction due to contact between the probe 2a and the surface of the sample S. Therefore, the determination unit 42 determines that the probe 2a is in contact with the sample surface if the amount of deflection indicated by the first detection signal output from the photodetector 62 exceeds the upper deflection threshold or if the amount of deflection indicated by the first detection signal is lower than the lower deflection threshold.

[0086] The second range is the range between the upper and lower limit thresholds of the torsion. The upper limit value is the amount of torsion of the cantilever 2 in the +Y direction due to contact between the probe 2a and the surface of the sample S. On the other hand, the lower limit value is the amount of torsion of the cantilever 2 in the -Y direction due to contact between the probe 2a and the sample surface. Therefore, the determination unit 42 determines that the probe 2a is in contact with the sample surface if the amount of torsion indicated by the second detection signal output from the photodetector 62 exceeds the upper limit value or if the amount of torsion indicated by the second detection signal is lower than the lower limit value. Thus, in Figure 4 In the two-dimensional coordinates of the deflection and torsion shown, if the position represented by the deflection indicated by the first detection signal and the torsion indicated by the second detection signal is outside the range shown by the slant line, it is determined that the probe 2a is in contact with the sample surface.

[0087] Next, the separation determination process of the first embodiment will be explained.

[0088] During the separation operation, if the determination unit 42 detects vibration of the cantilever 2 at a predetermined amplitude at the resonant frequency of the cantilever, it determines that the probe 2a has separated from the sample surface. Furthermore, the predetermined amplitude is a range smaller than the displacement of the cantilever 2 when the probe 2a is in contact with the sample surface, based on the free position of the cantilever 2.

[0089] For example, the so-called separation determination processing is processing of determining whether or not a rate of change in amplitude in a flexure direction of the cantilever 2 near the resonance frequency is a prescribed value or more in a case where the sample S is caused to act in a direction away from the probe 2a at a speed exceeding the response speed of the cantilever 2. Here, the case where the rate of change in amplitude in the flexure direction is the prescribed value or more indicates a case where the amplitude in the flexure direction sharply increases. In addition, the so-called separation determination processing can also adopt processing of determining whether or not the frequency of vibration of a prescribed amplitude of the cantilever 2 is the resonance frequency of the cantilever in a case where the sample S is caused to act in a direction away from the probe 2a at a speed exceeding the response speed of the cantilever 2.

[0090] The determination section 42 determines that the probe 2a is separated from the sample surface in a case where it is determined that the vibration frequency of the cantilever 2 is the resonance frequency of the cantilever and the rate of change in amplitude of the cantilever 2 is a prescribed value or more in a case where the sample S is caused to act in a direction away from the probe 2a at a speed exceeding the response speed of the cantilever 2. On the other hand, the determination section 42 determines that the probe 2a is in contact with the sample surface (not separated) in a case where it is determined that the frequency of vibration of the cantilever 2 is not the resonance frequency of the cantilever or the rate of change in amplitude of the cantilever 2 is less than the prescribed value in a case where the sample S is caused to act in a direction away from the probe 2a at a speed exceeding the response speed of the cantilever 2.

[0091] Next, the separation determination processing of the first embodiment will be described using Figure 5 , Figure 6 The effects of the separation determination processing of the first embodiment will be described.

[0092] Figure 5 is a graph showing the state of the cantilever 2 in a case where the sample S is caused to act in a direction away from the probe 2a at a normal speed. Figure 6 is a graph showing the state of the cantilever 2 in the separation action of the first embodiment (in a case where the sample S is caused to act in a direction away from the probe 2a at a speed exceeding the response speed of the cantilever 2). Figure 5 (a) of Figure 6 (a) of shows a side view of the cantilever 2 as viewed from the -Y direction, Figure 5 (b) of Figure 6 (b) of shows a side view of the cantilever 2 as viewed from the -X direction.

[0093] The determination section 42 determines that the probe 2a is in contact with the sample surface in a case where at least either the flexure amount or the twist amount of the cantilever 2 is outside the prescribed range in the contact determination processing described above. Therefore, if considered in pairs, the probe 2a is not in contact with the sample surface, that is, the probe 2a is separated from the sample surface, as long as the flexure amount and the twist amount of the cantilever 2 are within the prescribed ranges, respectively.

[0094] However, there are cases where an adsorptive force exists between the probe 2a and the sample surface. Therefore, as shown in FIG. 8, in a case where the sample S is separated from the probe 2a at a normal speed, even if the amount of deflection and the amount of twist of the cantilever 2 are within the prescribed ranges, respectively, the probe 2a comes into contact with the sample surface due to the adsorptive force in some cases. In addition, the adsorptive force between the probe 2a and the sample S differs at each measurement point in some cases. Therefore, it is not possible to uniquely set the threshold values of the amounts of deflection and twist, respectively, at which the probe 2a is separated from the sample surface. Figure 5

[0095] On the other hand, as shown in FIG. 9, in the first embodiment, the driving control section 43 separates the sample S from the probe 2a at a speed exceeding the response speed of the cantilever 2. Here, the probe 2a cannot move faster than the response speed of the cantilever 2. Therefore, when the sample S is separated from the probe 2a at a speed exceeding the response speed of the cantilever 2, even in a case where an adsorptive force exists between the probe 2a and the sample surface, the probe 2a can be immediately separated from the state of being in contact with the sample surface. Figure 6

[0096] Therefore, the cantilever 2 resonates in the amplitude from the state of the probe 2a being in contact with the sample surface, that is, the state of the probe 2a being pressed upward to the free state. In other words, the amplitude of the cantilever 2 in the deflection direction at the resonance frequency sharply increases. Therefore, the determination section 42 of the first embodiment determines that the probe 2a is separated with respect to the sample surface in a case where the vibration of the cantilever 2 in the amplitude in the deflection direction is detected using the resonance frequency (including the frequency of higher order) of the cantilever 2 in the separation operation. Thus, even in a case where an adsorptive force exists between the probe 2a and the sample surface, it is possible to reliably detect that the probe 2a is separated with respect to the sample surface.

[0097] In addition, in a case where the separation is performed at a speed exceeding the response speed of the cantilever 2, in a case where no adsorptive force exists between the probe 2a and the sample surface, the vibration from the deflection state of the cantilever 2 occurs at the resonance frequency in the deflection direction.

[0098] Next, the flow of the separation determination processing of the first embodiment will be described. Figure 7

[0099] ​​​The determination unit 42 determines whether the amount of deflection indicated by the first detection signal output from the light detection unit 62 is within a first range (step S201). If the determination unit 42 determines that the amount of deflection indicated by the first detection signal output from the light detection unit 62 is within the first range, it determines whether the amount of torsion indicated by the second detection signal output from the light detection unit 62 is within a second range (step S202). On the other hand, if the determination unit 42 determines that the amount of deflection indicated by the first detection signal output from the light detection unit 62 is outside the first range, it determines that the probe 2a has not separated from the sample surface (step S206).

[0100] If the determination unit 42 determines that the amount of distortion indicated by the second detection signal output from the light detection unit 62 is within the second range, it determines whether the frequency of the first detection signal is the resonant frequency of the cantilever 2 (step S203). On the other hand, if the determination unit 42 determines that the amount of distortion indicated by the second detection signal output from the light detection unit 62 is outside the second range, it determines that the probe 2a has not separated from the sample surface (step S206).

[0101] If the determination unit 42 determines that the frequency of the first detection signal is the resonant frequency of the cantilever 2, it determines whether the rate of change of the deflection amount shown by the first detection signal exceeds a predetermined value (step S204). On the other hand, if the determination unit 42 determines that the frequency of the first detection signal is not the resonant frequency of the cantilever 2, it determines that the probe 2a has not separated from the sample surface (step S206).

[0102] If the change in the amount of deflection indicated by the first detection signal exceeds a predetermined value, the determination unit 42 determines that the probe 2a has separated from the sample surface (step S205). On the other hand, if the change in the amount of deflection indicated by the first detection signal is less than a predetermined value, the determination unit 42 determines that the probe 2a has not separated from the sample surface (step S206).

[0103] In addition, Figure 7 In this embodiment, the determination unit 42 may perform the processing of step S201 after the processing of step S201, but is not limited to this. The determination unit 42 may perform the processing of step S201 after the processing of step S202, or it may perform the processing of steps S201 and S202 in parallel. Similarly, the determination unit 42 may perform the processing of step S204 after the processing of step S203, or it may perform the processing of steps S203 and S204 in parallel.

[0104] As described above, the scanning probe microscope A of the first embodiment determines that the probe 2a is separated from the sample surface when the vibration of the prescribed amplitude of the cantilever 2 is detected at the resonance frequency (including the high-order frequency) of the cantilever 2 in the separation operation of separating the sample S from the probe 2a at a speed exceeding the response speed of the cantilever 2. Then, the scanning probe microscope A stops the separation operation of the Z-direction drive device 51 at the timing when it is determined that the probe 2a is separated from the sample surface, and relatively moves the probe 2a and the sample in such a manner that the probe 2a is positioned directly above the next measurement point of the sample S.

[0105] Thus, in the scanning probe microscope A, since the separation operation is performed at the optimum separation distance at each measurement point of the sample S, the measurement of the convex-concave shape on the sample surface can be performed in the shortest time. Therefore, the scanning probe microscope A can improve the measurement efficiency of the convex-concave shape on the sample surface.

[0106] Here, the first detection signal indicating the deflection amount sometimes drifts due to temperature change or the like. Therefore, in the past, the influence of the drift has been considered to determine the separation distance, and thus the optimum separation distance could not be determined in advance.

[0107] On the other hand, the scanning probe microscope A of the first embodiment can sequentially determine whether the probe 2a is separated from the sample surface even when the first detection signal drifts. Therefore, the scanning probe microscope A can perform the separation operation at the optimum separation distance without being affected by the drift.

[0108] In addition, in the above-described embodiment, the Z-direction drive device 51 needs to perform the separation operation of moving the sample S in the direction of separating from the probe 2a at high speed without generating vibration. For this reason, the Z-direction drive device 51 can employ a structure using a stacked piezoelectric element 510. For example, as shown in FIG. 6, the Z-direction drive device 51 has the stacked piezoelectric element 510, leaf springs 511 and 512 having the same spring constant, support plates 521 and 522 respectively fixing the leaf springs 511 and 512, and a stage 530. Figure 8

[0109] The sample stage 4 and the sample S are provided at one end of the stacked piezoelectric element 510 via the leaf spring 511. In addition, the stage 530 is provided at the other end of the stacked piezoelectric element 510 via the leaf spring 512. The weight of the stage 530 corresponds to the weight of the sample stage 4 and the sample S.

[0110] Further, when the Z-direction drive device 51 is fixed, it is fixed at the respective centers of gravity of the support plates 521 and 522. Therefore, the Z-direction drive device 51 can not transmit vibration to the surroundings even in the separation operation.

[0111] (Second Embodiment)​

[0112] Next, the scanning probe microscope B of the second embodiment will be described using the drawings. The separation determination processing of the scanning probe microscope B of the second embodiment is different from the "separation determination processing" of the first embodiment, and the separation determination processing is performed based on a change in the velocity of the cantilever 2 in the flexure direction. In addition, the "contact determination processing" of the scanning probe microscope B of the second embodiment performs the same processing as the "contact determination processing" of the first embodiment.

[0113] Figure 9 is a view showing an example of the schematic configuration of the scanning probe microscope B of the second embodiment. As shown in Figure 9 the scanning probe microscope B has the cantilever 2, the sample stage 4, the movement driving section 5, the displacement detecting section 6, and the control device 7B.

[0114] The control device 7B has a determination section 42B, a driving control section 43B, and a measurement section 44.

[0115] The determination section 42B performs the contact determination processing of determining whether or not the probe 2a is in contact with the sample surface based on the first detection signal and the second detection signal output from the light detecting section 62. The contact determination processing of this determination section 42B is the same as the contact determination processing of the first embodiment.

[0116] In addition, the determination section 42B performs the separation determination processing of determining whether or not the probe 2a is separated from the sample surface based on the first detection signal and the second detection signal output from the light detecting section 62. Specifically, the separation determination processing of the determination section 42B is processing of determining the separation of the probe 2a from the sample surface based on a change in the velocity of the cantilever 2 in the flexure direction in the separation operation.

[0117] The driving control section 43B causes the sample S to operate in a direction away from the probe 2a at a velocity lower than the response velocity of the cantilever 2 in the separation operation. That is, in the separation operation, the sample S is caused to operate in a direction away from the probe 2a at a velocity higher than the response velocity of the cantilever 2 in the first embodiment, but the sample S is caused to operate in a direction away from the probe 2a at a velocity lower than the response velocity of the cantilever 2 in the second embodiment. In addition, the operation related to the driving control section 43B other than the above-described separation operation is the same as the driving control section 43.

[0118] Next, the separation determination processing of the second embodiment will be described.

[0119] The determination section 42B determines the separation of the probe 2a from the sample surface based on a change in the velocity of the cantilever 2 in the flexure direction in the separation operation of causing the sample S to operate in a direction away from the probe 2a at a velocity lower than the response velocity of the cantilever 2.

[0120] Here, the determination unit 42B can calculate the velocity change of the cantilever 2 in the deflection direction based on the ratio (Vd / H) of the deflection amount Vd of the cantilever 2 to the distance H that separates the sample S from the probe 2a. In addition, the determination unit 42B can calculate the velocity change of the cantilever 2 in the deflection direction by differentiating the deflection amount Vd of the cantilever 2.

[0121] If, during the separation action in which the sample S is separated from the probe 2a at a speed lower than the response speed of the cantilever 2, the determination unit 42B determines that the probe 2a has left the sample surface if the speed of the cantilever 2 in the flexural direction is lower than a predetermined value.

[0122] Furthermore, if the velocity direction of the cantilever 2 reverses during the separation action of separating the sample S from the probe 2a at a speed lower than the response speed of the cantilever 2, the determination unit 42B determines that the probe 2a has left the sample surface.

[0123] The effects of the separation determination process in the second embodiment will now be explained using the accompanying drawings.

[0124] Figure 10 It is a graph showing the velocity change of the cantilever 2 in the deflection direction during the separation action in the second embodiment. Figure 10 (a) is a graph showing the velocity change of cantilever 2 in the deflection direction when there is no adsorption force between probe 2a and sample S. Figure 10 (b) is a graph showing the velocity change of cantilever 2 in the deflection direction when the adsorption force between probe 2a and sample S is present. Figure 11 This diagram shows the case of the cantilever 2 during the separation operation of the second embodiment 1 (when the sample S moves in the direction of separation from the probe 2a at a speed less than or equal to the response speed of the cantilever 2). Figure 11 (a) shows a side view of cantilever 2 as viewed from the -Y direction. Figure 11 (b) shows a side view of the cantilever 2 as viewed from the -X direction.

[0125] During the separation action, when probe 2a is in contact with the sample surface, the velocity of cantilever 2 in the deflection direction is constant.

[0126] Here, as Figure 10As shown in (a), when there is no adsorption force between probe 2a and sample S, the change in the deflection of cantilever 2, i.e., the velocity of cantilever 2, is approximately zero in the free state when probe 2a separates from the sample surface. Therefore, when the separation action of separating sample S from probe 2a at a velocity lower than the response velocity of cantilever 2 is less than a predetermined value, the determination unit 42B determines that probe 2a has left the sample surface. Thus, the determination unit 42B can reliably detect the separation of probe 2a and sample S when there is no adsorption force between probe 2a and sample S. Furthermore, this predetermined value is less than the velocity of cantilever 2 in the deflection direction when probe 2a is in contact with the sample surface.

[0127] On the other hand, such as Figure 10 (b) Figure 11 As shown, when there is an adsorption force between probe 2a and sample S, the deflection based on this adsorption force returns when probe 2a separates from the sample surface, thus reversing the sign of the Vd / H value. That is, when probe 2a separates from the sample surface, the velocity direction of cantilever 2 reverses. Therefore, when the velocity direction of cantilever 2 reverses during the separation operation, the determination unit 42B determines that probe 2a has left the sample surface. Thus, the determination unit 42B can reliably detect the separation of probe 2a from sample S even when an adsorption force exists between probe 2a and sample S.

[0128] Next, use Figure 12 The process of separation determination in the second embodiment will be explained.

[0129] The determination unit 42B determines whether the amount of deflection indicated by the first detection signal output from the light detection unit 62 is within a first range (step S301). If the determination unit 42B determines that the amount of deflection indicated by the first detection signal output from the light detection unit 62 is within the first range, it determines whether the amount of torsion indicated by the second detection signal output from the light detection unit 62 is within a second range (step S302). On the other hand, if the determination unit 42B determines that the amount of deflection indicated by the first detection signal output from the light detection unit 62 is outside the first range, it determines that the probe 2a has not separated from the sample surface (step S306).

[0130] If the determination unit 42B determines that the amount of torsion indicated by the second detection signal output from the light detection unit 62 is within the second range, it determines whether the speed of the cantilever 2 calculated based on the first detection signal is below a predetermined value (step S303). On the other hand, if the determination unit 42B determines that the amount of torsion indicated by the second detection signal output from the light detection unit 62 is outside the second range, it determines that the probe 2a has not separated from the sample surface (step S306).

[0131] If the determination unit 42B determines that the speed of the cantilever 2 is below a predetermined value, it determines that the probe 2a is separated from the sample surface (step S305). On the other hand, if the determination unit 42B determines that the speed of the cantilever 2 exceeds a predetermined value, it determines whether the speed direction of the cantilever 2 is reversed (step S304).

[0132] If the determination unit 42B determines that the velocity direction of the cantilever 2 has reversed, it determines that the probe 2a has separated from the sample surface (step S305). On the other hand, if the determination unit 42B determines that the velocity direction of the cantilever 2 has not reversed, it determines that the probe 2a has not separated from the sample surface (step S306).

[0133] In addition, Figure 12 In this embodiment, the determination unit 42B may perform the processing of step S301 after the processing of step S301, but is not limited to this. The determination unit 42B may perform the processing of step S301 after the processing of step S302, or it may perform the processing of steps S301 and S302 in parallel. Similarly, the determination unit 42B may perform the processing of step S304 after the processing of step S303, or it may perform the processing of steps S303 and S304 in parallel.

[0134] As described above, in the separation action of separating the sample S from the probe 2a at a speed not exceeding the response speed of the cantilever 2, the scanning probe microscope B of the second embodiment determines the separation of the probe 2a from the sample surface based on the speed change of the cantilever 2 in the flexural direction.

[0135] For example, if the velocity of the cantilever 2 in the flexural direction is below a predetermined value, the determination unit 42B determines that the probe 2a has left the sample surface. Furthermore, if the velocity direction of the cantilever 2 is reversed, the determination unit 42B determines that the probe 2a has left the sample surface.

[0136] Therefore, in the scanning probe microscope B, even when the adsorption force between the probe 2a and the sample S exists, it can operate at the optimal separation distance at each measurement point of the sample S, thus enabling the measurement of the uneven shape on the sample surface in the shortest possible time. Therefore, the scanning probe microscope B can improve the measurement efficiency of the uneven shape on the sample surface.

[0137] In the second embodiment, the sample and probe 2a are separated by lowering the sample S during the separation operation, but this is not a limitation. The drive control unit 43B may also separate the sample S and probe 2a by raising the probe 2a during the separation operation.

[0138] (Third Implementation)

[0139] The scanning probe microscope C of the third embodiment will now be described using the accompanying drawings. The separation determination process of the scanning probe microscope C of the third embodiment differs from the "separation determination process" of the first embodiment; instead, the separation determination process is performed based on an increase in the amplitude of the vibration of the cantilever 2 or a change in the vibration frequency. Furthermore, the "contact determination process" of the scanning probe microscope C of the third embodiment is performed in the same manner as the "contact determination process" of the first embodiment.

[0140] Figure 13 This is a diagram illustrating an example of the schematic structure of the scanning probe microscope C according to the third embodiment. Figure 13 As shown, the scanning probe microscope C has a cantilever 2, a sample stage 4, a moving drive unit 5, a displacement detection unit 6, and a control device 7C.

[0141] The control device 7C includes a determination unit 42C, a drive control unit 43B, and a measurement unit 44.

[0142] The determination unit 42C performs a contact determination process to determine whether the probe 2a is in contact with the sample surface based on the first detection signal and the second detection signal output from the photodetector 62. This contact determination process of the determination unit 42C is the same as that of the contact determination process in the first embodiment.

[0143] The determination unit 42C performs a separation determination process to determine whether the probe 2a is separated from the sample surface based on the first detection signal and the second detection signal output from the detection unit 62.

[0144] Below, refer to Figure 14 The separation determination process of the third embodiment will be explained.

[0145] In the separation determination process of the third embodiment, it is roughly divided into two methods: "a method for detecting changes in the amplitude of deflection or torsion caused by the thermal vibration of the cantilever" and "a method for detecting changes in the resonant frequency of deflection or torsion caused by the thermal vibration of the cantilever".

[0146] (A method for detecting changes in the amplitude of deflection or torsion caused by the thermal vibration of a cantilever)

[0147] The base of cantilever 2 is fixed, while the front end (probe 2a) is free. Therefore, when probe 2a is separated from the sample surface without contact, cantilever 2 resonates with a large amplitude due to thermal vibration. Hereinafter, the state of cantilever 2 with a fixed base and a free front end (probe 2a) is referred to as the cantilever state.

[0148] On the other hand, when probe 2a is in contact with the sample surface, probe 2a is fixed by the sample surface. That is, both the base end and the front end of cantilever 2 are fixed ends. Therefore, the amplitude of the resonance caused by thermal vibration is smaller than the amplitude in the cantilever state. Hereinafter, the state of cantilever 2 with both the base end and the front end fixed ends will be referred to as the double-support state.

[0149] Therefore, when the probe 2a transitions from a state of contact with the sample surface to a state of separation from the sample surface, the amplitude of the vibration of the cantilever 2 increases. Thus, the determination unit 42C determines the separation of the probe 2a from the sample surface based on the increase in the amplitude of the vibration of the cantilever 2 during the separation operation. For example, if the amplitude of the vibration of the cantilever 2 is above a predetermined value during the separation operation, the determination unit 42C determines that the probe 2a and the sample surface have separated. Furthermore, the amplitude of the vibration of the cantilever 2 is at least one of flexural amplitude and torsional amplitude. This predetermined value is set based on the amplitude of the vibration of the cantilever 2 in the double-support state.

[0150] (A method for detecting changes in the resonant frequency of deflection or torsion caused by the thermal vibration of a rod)

[0151] The resonant frequency of the cantilever 2, which resonates due to thermal vibration, differs between the cantilever state and the double-supported state. Therefore, the resonant frequency of the cantilever 2 changes when the probe 2a transitions from a state of contact with the sample surface to a state of separation from the sample surface. Hereinafter, the resonant frequency of the cantilever 2 in the cantilever state will be referred to as the cantilever resonant frequency. On the other hand, the resonant frequency of the cantilever 2 in the double-supported state will be referred to as the double-support resonant frequency.

[0152] Therefore, the determination unit 42C determines the separation of probe 2a from the sample surface based on the change in the resonant frequency of the cantilever 2's vibration during the separation operation. For example, if the change in the vibration frequency of the cantilever 2 is above a predetermined value during the separation operation, the determination unit 42C determines that probe 2a and the sample surface have separated. Furthermore, the vibration frequency of the cantilever 2 is the frequency of vibration in at least one of the flexural and torsional directions. This predetermined value is set based on the resonant frequency of the double support.

[0153] Furthermore, in either of the two separation determination processes described above, the condition for determining that the probe 2a is separated from the sample surface is that the amount of deflection indicated by the first detection signal output from the optical detection unit 62 is within a first range and the amount of torsion indicated by the second detection signal output from the optical detection unit 62 is within a second range.

[0154] As described above, the scanning probe microscope C of the third embodiment determines the separation of probe 2a from the sample surface based on the increase in the amplitude of the vibration of cantilever 2 or the change in the vibration frequency during the separation operation. Therefore, even when there is an adsorption force between probe 2a and sample S, the scanning probe microscope C can operate at the optimal separation distance at each measurement point of sample S, thus enabling the measurement of the uneven shape on the sample surface in the shortest possible time. Therefore, the scanning probe microscope C can improve the efficiency of measuring the uneven shape on the sample surface.

[0155] In addition, the scanning probe microscope C detects the separation of probe 2a from the sample surface through thermal vibration, so no new structure is required.

[0156] (Fourth Implementation)

[0157] The scanning probe microscope D of the fourth embodiment will now be described using the accompanying drawings. The scanning probe microscope D of the fourth embodiment has an excitation unit 3, and unlike the "separation determination process" of the first embodiment, the separation determination process is performed based on the amplitude change of a predetermined frequency of the cantilever 2 in the flexure or torsion direction. Furthermore, the "contact determination process" of the scanning probe microscope D of the fourth embodiment is performed in the same manner as the "contact determination process" of the first embodiment.

[0158] Figure 15 This is a diagram illustrating an example of the schematic structure of the scanning probe microscope D according to the fourth embodiment. (See diagram below.) Figure 15 As shown, the scanning probe microscope D has a cantilever 2, an excitation unit 3, a sample stage 4, a moving drive unit 5, a displacement detection unit 6, and a control device 7D.

[0159] The excitation unit 3 causes the specimen S and the cantilever 2 to vibrate relative to each other at a predetermined frequency during the separation operation. For example, the excitation unit 3 can excite the cantilever 2 or the specimen stage 4. In addition, the direction in which the specimen S and the cantilever 2 vibrate relative to each other at the predetermined frequency can be either a direction perpendicular to the horizontal plane of the specimen stage 4 (Z direction) or a horizontal direction (Y direction). In the following description, this predetermined frequency will be referred to as the excitation frequency.

[0160] The control device 7D includes a determination unit 42D, a drive control unit 43D, and a measurement unit 44.

[0161] The determination unit 42D performs a separation determination process to determine whether the probe 2a has separated from the sample surface based on the first detection signal and the second detection signal output from the photodetector 62. Specifically, the separation determination process of the determination unit 42D is a process of determining the separation of the probe 2a from the sample surface based on the change in the amplitude of the excitation frequency of the cantilever 2 in the flexure direction or torsion direction.

[0162] The drive control unit 43D has the same function as the drive control unit 43B. Furthermore, the drive control unit 43D controls the operation of the excitation unit 3. That is, the drive control unit 43D controls the relative vibration of the sample S and the cantilever 2.

[0163] Below, refer to Figure 16 , 17 Section 18 explains the separation determination process of the fourth embodiment.

[0164] The separation determination process in the fourth embodiment is roughly divided into three methods: "a method for detecting the decrease in amplitude of the cantilever at the non-resonant frequency in the flexure or torsion direction", "a method for detecting the increase in amplitude of the cantilever at the resonant frequency in the flexure or torsion direction", and "a method for detecting the decrease in amplitude of the cantilever at the resonant frequency in the flexure or torsion direction".

[0165] (Methods for detecting the decrease in amplitude of the cantilever at non-resonant frequencies in the flexural or torsional directions:) Figure 16 )

[0166] In this method, the excitation frequency is set to the non-resonant frequency of the cantilever 2. Furthermore, during the separation operation, the excitation unit 3 causes the sample S and the cantilever 2 to vibrate relatively slightly at the non-resonant frequency. In this case, with the probe 2a in contact with the sample surface, the angle of the cantilever 2, with the probe 2a as the fulcrum, changes. That is, in the detection method using an optical lever, the change in the angle of the cantilever 2 is detected as a larger amplitude of the cantilever 2.

[0167] On the other hand, during the separation action, when probe 2a separates from the sample surface, probe 2a moves away from the sample surface, thus reducing the angle change of cantilever 2. Therefore, in the detection method using the optical lever, the smaller amplitude of cantilever 2 is detected. Thus, as the state changes from contact between probe 2a and the sample surface to separation of probe 2a from the sample surface, the amplitude of cantilever 2 decreases. Here, the amplitude of cantilever 2 refers to at least one of the amplitude in the deflection direction and the amplitude in the torsion direction. The amplitude in the deflection direction is the amount of deflection indicated by the first detection signal. The amplitude in the torsion direction is the amount of torsion indicated by the second detection signal.

[0168] Therefore, if the reduction in amplitude of the cantilever 2 at the non-resonant frequency in the deflection or torsion direction exceeds a predetermined value during the separation operation, the determination unit 42D determines that the probe 2a has left the sample surface. Furthermore, this predetermined value is set based on the amount of deflection or torsion detected during the separation operation when the probe 2a is in contact with the sample surface.

[0169] Furthermore, in this method, the cantilever 2 can be made to vibrate slightly in the flexural direction at a non-resonant frequency, or it can be made to vibrate in the horizontal direction. Additionally, in the fourth embodiment, the sample S can be made to vibrate slightly in the flexural direction at a non-resonant frequency, or it can be made to vibrate in the horizontal direction.

[0170] (A method for detecting the increase in amplitude of a cantilever at its resonant frequency in the flexural or torsional direction;) Figure 17 )

[0171] In this method, the excitation frequency is set to the cantilever resonant frequency. Furthermore, during the separation operation, the excitation unit 3 causes the sample S and the cantilever 2 to vibrate relatively slightly at the cantilever resonant frequency. In this situation, with the probe 2a in contact with the sample surface, the cantilever 2 is in a double-support state. Therefore, even if the cantilever 2 is excited by the excitation unit 3 at the cantilever resonant frequency, it will not resonate but will vibrate with a small amplitude.

[0172] On the other hand, during the separation operation, when probe 2a separates from the sample surface, probe 2a leaves the sample surface, and therefore cantilever 2 is in a cantilever state. Thus, cantilever 2 is excited by excitation unit 3 at the cantilever resonant frequency, thereby resonating and vibrating with a large amplitude.

[0173] Therefore, when the probe 2a transitions from a state of contact with the sample surface to a state of separation from the sample surface, the amplitude of the vibration of the cantilever 2 at the cantilever resonant frequency increases. Therefore, the determination unit 42D determines the separation of the probe 2a from the sample surface during the separation operation based on the increase in the amplitude of the vibration of the cantilever 2 at the cantilever resonant frequency. For example, if the increase in the amplitude of the vibration of the cantilever 2 at the cantilever resonant frequency exceeds a predetermined value during the separation operation, the determination unit 42C determines that the probe 2a and the sample surface have separated. Furthermore, the amplitude of the vibration of the cantilever 2 is at least one of flexural amplitude and torsional amplitude.

[0174] Furthermore, in this method, the cantilever 2 can be made to vibrate slightly in the flexural direction at the cantilever resonant frequency, or it can be made to vibrate slightly in the horizontal direction at the cantilever resonant frequency. Additionally, the sample S can be made to vibrate slightly in the flexural direction at the cantilever resonant frequency, or it can be made to vibrate slightly in the horizontal direction at the cantilever resonant frequency.

[0175] However, in the case of minute vibrations in the flexural direction, the excitation frequency is the cantilever resonant frequency of cantilever 2 in the flexural direction. On the other hand, in the case of minute vibrations in the horizontal direction, the excitation frequency is the cantilever resonant frequency of cantilever 2 in the horizontal direction.

[0176] (A method for detecting the decrease in amplitude of a cantilever at its resonant frequency in the flexural or torsional direction;)Figure 18 )

[0177] In this method, the excitation frequency is set to the double-support resonant frequency. Furthermore, during the separation operation, the excitation unit 3 causes the sample S and the cantilever 2 to vibrate relatively slightly at the double-support resonant frequency. In this case, with the probe 2a in contact with the sample surface, the cantilever 2 is in a double-support state. Therefore, the cantilever 2 is excited by the excitation unit 3 at the double-support resonant frequency, thereby resonating and vibrating with a larger amplitude.

[0178] On the other hand, during the separation operation, when probe 2a separates from the sample surface, probe 2a leaves the sample surface, and therefore cantilever 2 is in a cantilever state. Therefore, even if cantilever 2 is excited by excitation unit 3 at the dual-support resonant frequency, it will not resonate but will vibrate with a small amplitude.

[0179] Therefore, when the probe 2a transitions from a state of contact with the sample surface to a state of separation from the sample surface, the amplitude of the vibration of the cantilever 2 at the double-support resonant frequency decreases. Therefore, the determination unit 42D determines the separation of the probe 2a from the sample surface during the separation operation based on the decrease in the amplitude of the vibration of the cantilever 2 at the double-support resonant frequency. For example, if the decrease in the amplitude of the vibration of the cantilever 2 at the double-support resonant frequency exceeds a predetermined value during the separation operation, the determination unit 42C determines that the probe 2a and the sample surface have separated. Furthermore, the amplitude of the vibration of the cantilever 2 is at least one of the amplitude in the flexural direction and the amplitude in the torsional direction.

[0180] Furthermore, in this method, the cantilever 2 can be made to vibrate slightly in the flexural direction at the double-support resonant frequency, or it can be made to vibrate in the horizontal direction at the double-support resonant frequency. Additionally, the sample S can be made to vibrate slightly in the flexural direction at the double-support resonant frequency, or it can be made to vibrate in the horizontal direction at the double-support resonant frequency.

[0181] However, in the case of minute vibrations in the flexural direction, the excitation frequency is the double-support resonant frequency of cantilever 2 in the flexural direction. On the other hand, in the case of minute vibrations in the horizontal direction, the excitation frequency is the double-support resonant frequency of cantilever 2 in the horizontal direction.

[0182] Furthermore, in any one of the three separation determination processes of the fourth embodiment, the condition for determining that the probe 2a is separated from the sample surface is that the amount of deflection indicated by the first detection signal output from the optical detection unit 62 is within a first range and the amount of twist indicated by the second detection signal output from the optical detection unit 62 is within a second range.

[0183] As described above, the scanning probe microscope D of the fourth embodiment includes: an excitation unit 3 that vibrates the sample S and the cantilever 2 relative to each other at a predetermined frequency during the separation operation; and a determination unit 42D that determines the separation of the probe 2a from the sample surface based on the change in amplitude of the cantilever 2 at a predetermined frequency in the flexural or torsional direction during the separation operation. Therefore, even in the presence of an adsorption force between the probe 2a and the sample S, the scanning probe microscope D can operate at an optimal separation distance at each measurement point of the sample S, thus enabling the measurement of the uneven shape on the sample surface in the shortest possible time. Therefore, the scanning probe microscope D can improve the measurement efficiency of the uneven shape on the sample surface.

[0184] Furthermore, in the fourth embodiment, the method of small vibrations at a non-resonant frequency in the flexural or torsional direction is suitable for situations where the amplitude decreases sharply at the instant the probe 2a separates from the sample surface, resulting in a fast response and high-speed operation.

[0185] On the other hand, the method of applying a small amplitude using the resonant frequency (cantilever resonant frequency, double-support resonant frequency) has less impact on the determination of concave and convex shapes because it can detect with a smaller amplitude than non-resonant methods.

[0186] (Fifth Implementation)

[0187] The scanning probe microscope E according to the fifth embodiment will now be described using the accompanying drawings. The scanning probe microscope E of the fifth embodiment, like the fourth embodiment, has an excitation unit 3. Unlike the "separation determination process" of the first embodiment, the separation determination process is performed based on the phase difference between the phase of the vibration of the cantilever 2 in the flexural or torsional direction and the phase of the resonant frequency of the excitation through the excitation unit 3. Furthermore, the "contact determination process" of the scanning probe microscope E of the fifth embodiment is performed in the same way as the "contact determination process" of the first embodiment.

[0188] Figure 19 This is a diagram illustrating an example of the schematic structure of the scanning probe microscope E according to the fifth embodiment. Figure 19 As shown, the scanning probe microscope E has a cantilever 2, an excitation unit 3, a sample stage 4, a moving drive unit 5, a displacement detection unit 6, and a control device 7E.

[0189] The control device 7E includes a determination unit 42E, a drive control unit 43D, and a measurement unit 44.

[0190] The determination unit 42E performs a separation determination process to determine whether the probe 2a has separated from the sample surface based on the first detection signal and the second detection signal output from the photodetector 62. Specifically, the separation determination process of the determination unit 42E is to determine the separation of the probe 2a from the sample surface based on the phase difference between the phase of the vibration of the cantilever 2 in the flexural or torsional direction and the phase of the resonant frequency of the excitation by the excitation unit 3 during the separation operation.

[0191] Next, use Figure 20 The separation determination process of the fifth embodiment will be explained.

[0192] In this method, the excitation frequency is set to the cantilever resonant frequency. Furthermore, during the separation operation, the excitation unit 3 causes the sample S and the cantilever 2 to vibrate relatively slightly at the cantilever resonant frequency. In this case, with the probe 2a in contact with the sample surface, the cantilever 2 is in a double-support state. Therefore, even if the cantilever 2 is excited by the excitation unit 3 at the cantilever resonant frequency, it will not resonate but vibrate non-resonantly. Therefore, the phase difference between the phase of the cantilever 2's vibration and the phase of the excitation frequency excited by the excitation unit 3 is small.

[0193] On the other hand, during the separation operation, when probe 2a separates from the sample surface, probe 2a leaves the sample surface, and therefore cantilever 2 is in a cantilever state. Thus, cantilever 2 is excited by excitation unit 3 at the cantilever resonant frequency, thereby achieving resonance. Therefore, the phase difference between the vibration phase of cantilever 2 and the phase of the excitation frequency excited by excitation unit 3 is approximately 90 degrees. That is, the phase of cantilever 2's vibration is 90° behind the phase of the excitation frequency excited by excitation unit 3.

[0194] Therefore, when the probe 2a transitions from a state of contact with the sample surface to a state of separation from the sample surface, the phase difference between the phase of the vibration of the cantilever 2 and the phase of the excitation frequency excited by the excitation unit 3 increases. Therefore, during the separation operation, the determination unit 42E determines the separation of the probe 2a from the sample surface based on the phase difference between the phase of the vibration of the cantilever 2 in the flexural or torsional direction and the phase of the resonant frequency excited by the excitation unit 3. For example, if the phase difference between the phase of the vibration of the cantilever 2 in the flexural or torsional direction and the phase of the resonant frequency excited by the excitation unit 3 exceeds a predetermined value during the separation operation, the determination unit 42E determines that the probe 2a and the sample surface have separated.

[0195] Furthermore, in this method, the cantilever 2 can be made to vibrate slightly in the flexural direction at the cantilever resonant frequency, or it can be made to vibrate slightly in the horizontal direction at the cantilever resonant frequency. Additionally, the sample S can be made to vibrate slightly in the flexural direction at the cantilever resonant frequency, or it can be made to vibrate slightly in the horizontal direction at the cantilever resonant frequency.

[0196] However, in the case of minute vibrations in the flexural direction, the excitation frequency is the cantilever resonant frequency of cantilever 2 in the flexural direction. On the other hand, in the case of minute vibrations in the horizontal direction, the excitation frequency is the cantilever resonant frequency of cantilever 2 in the horizontal direction.

[0197] Furthermore, in the separation determination process of the fifth embodiment, the condition for determining that the probe 2a is separated from the sample surface is that the amount of deflection indicated by the first detection signal output from the optical detection unit 62 is within a first range and the amount of torsion indicated by the second detection signal output from the optical detection unit 62 is within a second range.

[0198] As described above, the scanning probe microscope E of the fifth embodiment includes: an excitation unit 3 that vibrates the sample S and the cantilever 2 relative to each other at a predetermined frequency during the separation operation; and a determination unit 42E that, during the separation operation, determines the separation of the probe 2a from the sample surface based on the phase difference between the phase of the vibration of the cantilever 2 in the flexural or torsional direction and the phase of the resonant frequency of the excitation by the excitation unit 3. Therefore, even when there is an adsorption force between the probe 2a and the sample S, the scanning probe microscope D can operate at the optimal separation distance at each measurement point of the sample S, thus enabling the measurement of the uneven shape on the sample surface in the shortest possible time. Therefore, the scanning probe microscope B can improve the measurement efficiency of the uneven shape on the sample surface.

[0199] As described above, in one embodiment of the present invention, the scanning probe microscope does not determine whether the probe 2a separates from the sample surface by a predetermined "separation distance" as in existing methods. Instead, it determines whether the probe 2a and the sample surface separate while the separation action is being performed, and stops the separation action if the separation action is determined to be successful. Then, after stopping the separation action, the scanning probe microscope moves the probe to the airspace above the next measurement point.

[0200] Here, in the separation process, the following method is also considered: if the deflection and torsion of the cantilever 2 are within the specified range, it is determined that the probe 2a is not in contact with the sample surface, that is, the probe 2a and the sample surface are separated. However, in this method, even if the deflection and torsion of the cantilever 2 are within the specified range, sometimes the probe 2a may still come into contact with the sample surface due to the aforementioned adsorption force, making it impossible to correctly detect the separation of the probe and the sample surface.

[0201] On the other hand, in one embodiment of the present invention, the scanning probe microscope applies any one of the separation determination processes described in the first to fifth embodiments during the separation operation, thereby reliably detecting the separation between the probe 2a and the sample surface.

[0202] In addition, during the movement of the scanning probe microscope from the point where the separation action stops until it reaches the next measurement point, any one of the separation determination processes described in the first to fifth embodiments can be performed, thereby preventing the probe 2a from colliding with the sample.

[0203] For example, the scanning probe microscope described above performs an approach action (1) and determines whether the probe 2a is in contact with the sample surface (2). If the scanning probe microscope determines that the probe 2a is in contact with the sample surface, it stops the approach action and measures the relative distance (3). Then, after measuring the relative distance, the scanning probe microscope begins a separation action and uses any one of the separation determination processes in the first to fifth embodiments to determine whether the probe 2a and the sample surface are separated (4). Then, if the scanning probe microscope determines that the probe 2a and the sample surface are separated, it stops the separation action (5) and moves the probe 2a to the airspace above the next measurement point (6). Here, while moving the probe 2a to the airspace above the next measurement point, the scanning probe microscope uses any one of the separation determination processes in the first to fifth embodiments to determine whether the probe 2a and the sample surface are separated. Then, while the scanning probe microscope determines that the probe 2a and the sample surface are separated, it continues the above movement; if it determines that the probe 2a and the sample surface are not separated, it returns to (5) and performs the separation action to begin any one of the separation determination processes in the first to fifth embodiments.

[0204] Therefore, in one embodiment of the present invention, the scanning probe microscope can avoid collision between the probe 2a and the sample during its movement to the next measurement point.

[0205] The control devices 7, 7B to 7E described in the above embodiments can be implemented using a computer. In this case, the function can be implemented by recording a program for implementing the function on a computer-readable recording medium, and then having the computer system read and execute the program recorded on the recording medium. Furthermore, the term "computer system" here refers to a system that includes hardware such as an OS or peripheral devices. The term "computer-readable recording medium" refers to removable media such as a flexible disk, optical disk, ROM, CD-ROM, or a storage device such as a hard disk built into the computer system. Moreover, the term "computer-readable recording medium" can also include a medium that dynamically holds the program for a short period of time, such as a communication line used to transmit the program via a network such as the Internet or a telephone line, and a medium that holds the program for a certain period of time, such as volatile memory inside the computer system serving as a server or client in this case. Furthermore, the program described above can be a program used to implement the above function, or a program that can implement the above function by combining it with a program already recorded in the computer system, or a program implemented using a programmable logic device such as a FPGA (Field Programmable Gate Array).

[0206] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the specific structure is not limited to these embodiments and may include designs that do not depart from the spirit of the present invention.

[0207] The execution order of actions, processes, steps, and stages in the apparatus, system, program, and method shown in the claims, specification, and drawings is not specifically indicated as "previous" or "before." Furthermore, it should be noted that any order is permissible as long as the output of a previous process is not used in a later process. Even if terms such as "firstly" or "nextly" are used for convenience in describing the flow of actions in the claims, specification, and drawings, this does not imply that the actions must be performed in that order.

Claims

1. A scanning probe microscope, wherein a probe is brought into contact with a sample surface, and the sample surface is scanned intermittently using the probe, comprising: A cantilever having the probe at its front end; The driving unit performs a separation action that separates the sample and the probe from the state where the probe is in contact with the sample surface; The excitation unit causes the specimen and the cantilever to vibrate relative to each other at a predetermined frequency during the separation action; The determination unit determines the separation of the probe relative to the sample surface based on the change in amplitude of the cantilever at a predetermined frequency in the flexure direction or the torsion direction during the separation action, wherein the amplitude in the flexure direction is the flexure amount and the amplitude in the torsion direction is the torsion amount. as well as The drive control unit stops the separation action of the drive unit when the determination unit determines that separation has occurred, so that the probe and the sample surface move relative to each other to the next measurement point of the sample.

2. The scanning probe microscope according to claim 1, wherein, The specified frequency is the non-resonant frequency of the cantilever. If, during the separation action, the determination unit determines that the probe has left the sample surface if the decrease in amplitude of the cantilever at the non-resonant frequency in the flexural or torsional direction exceeds a predetermined value.

3. The scanning probe microscope according to claim 1, wherein, The specified frequency is the resonant frequency of the cantilever when it is in contact with the sample. If, during the separation action, the determination unit determines that the probe has left the surface of the sample if the decrease in the amplitude of the cantilever in the flexural or torsional direction exceeds a predetermined value.

4. The scanning probe microscope according to claim 1, wherein, The specified frequency is the resonant frequency of the cantilever. If, during the separation action, the determination unit determines that the probe has left the sample surface if the increase in amplitude of the cantilever at the resonant frequency in the flexural or torsional direction exceeds a predetermined value.

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