Scanning probe microscope and control method

Abstract

A detecting mechanism (110) acquires first information indicating the position of a cantilever in the Z-axis direction and second information indicating the position of a sample S in the Z-axis direction or the position of a sample stand (14) in the Z-axis direction. An approach processing part (104) determines a speed reduction position on the basis of the first information and the second information. The approach processing part (104) controls a displacement mechanism so that an approach speed changes from high speed to low speed at the speed reduction position.

Description

Scanning probe microscope and control method

[0001] The present disclosure relates to a scanning probe microscope and a control method.

[0002] A so-called optical lever scanning probe microscope (SPM) includes a cantilever with a probe, a stage on which a sample is placed, and an optical microscope. The optical microscope can be moved independently of the cantilever and the stage by a user or the like. The user can use the optical microscope to visually check the positions of the sample and the probe.

[0003] The SPM can acquire an image of the topography of the sample surface by moving the cantilever probe along the surface of the sample and detecting the deflection of the cantilever. This type of SPM further includes a light irradiation unit that irradiates the cantilever with light and a light detection unit that receives the light reflected from the cantilever.

[0004] When an SPM starts observing a sample surface, it first performs an approach operation to bring the cantilever closer to the sample. Specifically, the approach operation involves gradually bringing the probe closer to the sample surface by moving the cantilever vertically downward. The SPM also moves the cantilever using feedback control based on the signal value indicated by the detection signal from the light detection unit. When the signal value reaches a preset target value, the SPM determines that the probe has approached the sample surface and stops the movement of the cantilever. The SPM then completes the approach operation, and observes the sample surface by scanning the cantilever horizontally.

[0005] Furthermore, Japanese Patent No. 2909828 (Patent Document 1) discloses a scanning tunneling microscope (STM) for measuring a sample. The STM does not have a cantilever, but instead includes a probe, a stage, and an optical microscope. The probe is fixed to the optical microscope. A sample is placed on the stage. In addition, the STM moves the stage using feedback control based on the tunnel current.

[0006] When the STM starts observing the surface of a sample, it moves the stage on which the sample is placed in the thickness direction of the sample, thereby performing an approach operation to bring the probe closer to the sample. When the probe and sample are close to each other, the STM starts measuring the sample.

[0007] To shorten the time required for this approach operation, the STM increases the stage movement speed. However, when the stage movement speed is increased, the sample and the probe may collide due to the above-mentioned feedback control. Therefore, the STM described in Patent Document 1 calculates the distance between the sample and the probe and, based on that distance, determines a speed reduction position where the stage speed should be reduced. The STM then moves the stage at high speed up to the speed reduction position, and when the stage reaches this speed reduction position, moves the stage at a low speed.

[0008] Patent No. 2909828

[0009] The SPM executes the above-mentioned feedback control during the approach operation. Therefore, strictly speaking, the cantilever stops after the control device issues a command to stop the cantilever, which poses a risk of the cantilever probe colliding with the sample. Therefore, it is conceivable to slow down the cantilever movement speed during the approach operation to prevent the probe from colliding with the sample. However, slowing down the cantilever movement speed would result in a significant increase in the time required for the approach operation.

[0010] It is also conceivable to apply the STM technology for determining the velocity reduction position described in Patent Document 1 to an SPM. However, as described above, in the STM, the probe is fixed relative to the optical microscope. On the other hand, in an SPM, as described above, the optical microscope is moved independently of the cantilever and the stage. Therefore, the STM technology, in which the probe is fixed relative to the optical microscope, cannot be applied to an SPM.

[0011] The present invention has been made to solve these problems, and aims to provide a scanning probe microscope and a control method that can perform an approach operation in a short time while reducing the risk of the cantilever coming into contact with the sample surface.

[0012] The scanning probe microscope of the present disclosure includes a sample stage, a cantilever, a displacement mechanism, a detection mechanism, and an approach processing unit. A sample is placed on the sample stage. The cantilever is scanned along the surface of the sample. The displacement mechanism changes the relative position of the sample stage and the cantilever in the thickness direction of the sample. The detection mechanism acquires first information, which is information about the position of the cantilever in the thickness direction, and second information, which is information about the position of the sample in the thickness direction or the position of the sample stage in the thickness direction. The approach processing unit controls the displacement mechanism at a predetermined approach speed so that the sample stage and the cantilever approach each other. Based on the first information and the second information, the approach processing unit determines a speed reduction position at which the approach speed is switched from high to low. The approach processing unit also controls the displacement mechanism so that the approach speed changes from high to low at the speed reduction position.

[0013] The control method disclosed herein is a method for controlling a scanning probe microscope. The scanning probe microscope includes a sample stage on which a sample is placed and a cantilever that scans along the surface of the sample. The relative position of the sample stage and the cantilever in the thickness direction of the sample is changed. The control method includes acquiring first information regarding the position of the cantilever in the thickness direction and second information regarding the position of the sample in the thickness direction or the position of the sample stage in the thickness direction. The control method includes changing the relative position at a predetermined approach speed so that the sample stage and the cantilever approach each other. The control method includes determining a speed reduction position at which the approach speed is switched from high to low, based on the first information and the second information. Changing the relative position includes changing the relative position so that the approach speed is switched from high to low at the speed reduction position.

[0014] The scanning probe microscope and control method of the present disclosure enable an approach operation to be performed in a short time while reducing the risk of the cantilever coming into contact with the sample surface.

[0015] FIG. 1 is a diagram schematically illustrating a configuration of an SPM according to the present disclosure; FIG. 2 is a diagram illustrating an example of a hardware configuration of an information processing device; FIG. 3 is a functional block diagram illustrating main functions of an information processing device; FIG. 4 is a diagram illustrating a method for determining a speed reduction position according to a first embodiment; FIG. 5 is a diagram illustrating a method for determining a speed reduction position according to the first embodiment; FIG. 6 is a flowchart illustrating a processing flow of an SPM according to the first embodiment; FIG. 7 is a diagram illustrating an example of a mode setting screen according to the first embodiment; FIG. 8 is an example of an input screen; FIG. 9 is a diagram illustrating a method for determining a speed reduction position according to a second embodiment; FIG. 10 is a diagram illustrating a method for determining a speed reduction position according to the second embodiment; FIG. 11 is a flowchart illustrating a processing flow of an SPM according to the second embodiment.

[0016] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals and their description will not be repeated.

[0017] First Embodiment [Configuration Example] Fig. 1 is a diagram schematically illustrating the configuration of a scanning probe microscope (SPM) according to the present disclosure. The scanning probe microscope is also referred to as SPM100. The SPM100 typically measures the shape of the surface of the sample S by utilizing a physical quantity acting between a probe 3 and the surface of the sample S. The SPM100 may also be an atomic force microscope (AFM). In this case, the physical quantity is an atomic force (attractive force or repulsive force).

[0018] 1 , the SPM 100 includes, as its main components, a measuring device 10, an information processing device 20, a display device 30, and an input device 40. The measuring device 10 includes, as its main components, an optical system 1, a cantilever 2, a fine movement mechanism 12 (scanner), a sample stage 14, an XY-direction driving unit 16, a Z-direction driving unit 18, a feedback signal generating unit 22, a first motor 61, a second motor 62, and an optical microscope 50. In this embodiment, the first motor 61 and the second motor 62 are typically stepping motors.

[0019] The surface of the sample stage 14 is a placement surface 14a. The sample S is placed on the placement surface 14a of the sample stage 14. In the following, the thickness direction of the sample S is referred to as the Z-axis direction, and the directions perpendicular to the Z-axis direction are referred to as the X-axis direction and the Y-axis direction. The Z-axis direction is also the height direction of the SPM 100.

[0020] The sample stage 14 is placed on the fine movement mechanism 12. The fine movement mechanism 12 is a moving device for changing the relative positional relationship between the sample S and the probe 3 during analysis of the sample S. The fine movement mechanism 12 has an XY scanner 12xy and a Z scanner 12z. The XY scanner 12xy moves the sample stage 14 in the X-axis direction and the Y-axis direction. The Z scanner 12z finely moves the sample stage 14 in the Z-axis direction. The XY scanner 12xy has a piezoelectric element that deforms in response to a voltage applied from the XY-direction driver 16. The Z scanner 12z has a piezoelectric element that expands and contracts in response to a voltage applied from the Z-direction driver 18. The Z scanner 12z expands and contracts due to this piezoelectric element. Note that the XY scanner 12xy and the Z scanner 12z are not limited to having a piezoelectric element.

[0021] The cantilever 2 is disposed opposite the sample stage 14. The cantilever 2 is formed in the shape of a leaf spring, and one end of the cantilever 2 is supported by the holder 4. In other words, this one end is a fixed end. The other end of the cantilever 2 is a free end, and is disposed opposite the sample S on the sample stage 14. In the example shown in FIG. 1 , it is disposed upward in the Z-axis direction. The tip of the free end of the cantilever 2 has a front surface and a back surface opposite the front surface. The front surface is the surface that faces the sample S. A probe 3 is disposed on the front surface so as to face the sample S. During analysis of the sample S, the cantilever 2 is scanned along the surface of the sample S.

[0022] A reflecting member 2a that reflects light is formed on the back surface of the cantilever 2. The reflecting member 2a may be coated with a predetermined material (such as aluminum or gold). A physical quantity (such as atomic force) acting between the probe 3 and the sample S displaces the tip of the free end of the cantilever 2 in the Z-axis direction.

[0023] An optical system 1 for detecting the amount of deflection of the cantilever 2 (i.e., the amount of displacement of the tip) is provided above the cantilever 2 in the Z-axis direction. When measuring the sample S, the optical system 1 irradiates a laser beam onto the back surface (reflecting member 2a) of the cantilever 2 and detects the laser beam reflected by the reflecting surface. Specifically, the optical system 1 has a laser light source 6, a beam splitter 5, a reflecting mirror 7, and a photodetector 8.

[0024] The laser light source 6 has a laser oscillator that emits laser light. The photodetector 8 has a photodiode that detects the incident laser light. The laser light LA ​​emitted from the laser light source 6 is reflected by the beam splitter 5 and irradiated onto the reflecting member 2a of the cantilever 2. The laser light reflected by the back surface of the cantilever 2 is further reflected by the reflecting mirror 7 and enters the photodetector 8.

[0025] The photodetector 8 has a light-receiving surface that is divided into multiple (for example, two) parts in the Z-axis direction (displacement direction) of the cantilever 2. Alternatively, the photodetector 8 has a light-receiving surface that is divided into four parts in the Z-axis and Y-axis directions. When the tip of the cantilever 2 is displaced in the Z-axis direction, the ratio of the amount of light irradiated onto the multiple light-receiving surfaces changes, and therefore the amount of deflection (amount of displacement) of the cantilever 2 can be detected based on the multiple amounts of light received.

[0026] The optical system 1 and the cantilever 2 constitute a "cantilever unit 35." The optical microscope 50 is disposed above the cantilever unit 35 in the Z-axis direction. The user adjusts the focus of the optical microscope 50 on the sample S to specify the observation range, and adjusts the irradiation position of the laser light to match the reflecting member 2a of the cantilever 2. Image data acquired by the optical microscope 50 is output to the information processing device 20.

[0027] The feedback signal generator 22 calculates the amount of deflection of the cantilever 2 by arithmetic processing of the detection signal provided by the photodetector 8. The feedback signal generator 22 controls the Z-direction position of the sample S so that the atomic force between the probe 3 and the sample S is constant. Hereinafter, this control is also referred to as "feedback control." Specifically, the feedback signal generator 22 calculates the deviation Sd between the calculated amount of deflection of the cantilever 2 and a target value, and calculates a control amount for driving the Z scanner 12z so that the deviation Sd becomes zero. The feedback signal generator 22 calculates a voltage value Vz for displacing the Z scanner 12z corresponding to this control amount. The feedback signal generator 22 outputs a voltage signal indicating the voltage value Vz to the Z-direction driver 18. The Z-direction driver 18 applies the voltage value Vz to the Z scanner 12z. In this way, the Z-direction driver 18 receives the voltage value input from the feedback signal generator 22 and applies a voltage based on the voltage value to the Z scanner 12z.

[0028] The information processing device 20 calculates a voltage value Vx in the X-axis direction and a voltage value Vy in the Y-axis direction according to preset scanning conditions, and outputs the calculated voltage values ​​to the XY-direction driving unit 16 so that the sample stage 14 moves in the X-axis and Y-axis directions relative to the probe 3. The XY-direction driving unit 16 applies the voltage values ​​Vx and Vy to the XY scanner 12xy.

[0029] The information processing device 20 mainly controls the operation of the measuring device 10. Measurement data indicating the feedback amount in the Z-axis direction (the voltage Vz applied to the Z scanner 12z and the deviation Sd) is output from the Z-axis driver 18 to the information processing device 20. The measurement data is transmitted for each measurement point determined at predetermined intervals in the Y-axis direction of the sample S. The information processing device 20 stores the measurement data. The information processing device 20 calculates the displacement amount of the sample S in the Z-axis direction from the voltage Vz based on pre-stored correlation information. This correlation information is information indicating the relationship between the voltage Vz and the displacement amount of the sample S (sample stage 14) in the Z-axis direction corresponding to the voltage Vz.

[0030] The calculated displacement amount is a value that reflects a value indicating the position in the Z-axis direction of the sample S (hereinafter also referred to as a "Z value"). The information processing device 20 calculates the displacement amount in the Z-axis direction of the sample S at each position in the X-axis and Y-axis directions within the scanning range, thereby creating two-dimensional or three-dimensional measurement data that represents the shape of the surface of the sample S.

[0031] The measurement data created by the information processing device 20 includes a value (Z value) indicating the position in the Z-axis direction at each position on the XY plane. The Z value is the height of the sample S at each position. For example, the position in the Z-axis direction is expressed by a Z coordinate with the origin as the reference point. The origin in the Z-axis direction is, for example, the position of the placement surface 14a when the sample stage 14 is in the lowest position. In this way, the SPM 100 (information processing device 20) measures the surface condition of the sample S based on the light reflected by the reflecting member 2a.

[0032] The display device 30 and the input device 40 are connected to the information processing device 20. The display device 30 is configured, for example, with a liquid crystal display (LCD) panel. The information processing device 20 displays information such as the surface shape of the sample S on the display device 30 based on the created measurement data. The information processing device 20 also displays image data acquired by the optical microscope 50, an input screen (described later), and the like on the display device 30. The input device 40 is, for example, a pointing device such as a keyboard or a mouse, and receives commands from a user. When a touch panel is used as the user interface, the input device 40 and the display device 30 are integrally formed. The information processing device 20 corresponds to the "control device" of the present disclosure.

[0033] Image data acquired by imaging with the optical microscope 50 is output to the information processing device 20. The information processing device 20 may cause the display device 30 to display the image data.

[0034] The user can adjust the focus of the optical microscope 50 on the sample S to identify the observation location, and can adjust the irradiation position of the laser light in accordance with the cantilever 2. The cantilever 2 is disposed between the optical microscope 50 and the sample stage 14 in the Z-axis direction.

[0035] The cantilever unit 35 can move in the X-axis, Y-axis, and Z-axis directions by the driving force of the first motor 61. The information processing device 20 can control the first motor 61 by outputting a pulse signal to the first motor 61. The information processing device 20 can determine the amount of movement of the cantilever unit 35 based on the number of pulses in the pulse signal. The amount of movement of the cantilever unit 35 is, for example, the amount of movement from the initial position of the cantilever unit 35. The information processing device 20 can also control the speed of movement of the cantilever unit 35 (cantilever 2) by controlling the frequency of the pulse signal applied to the first motor 61. For example, as described below, the information processing device 20 can move the cantilever unit 35 (cantilever 2) at high speed or low speed.

[0036] The first motor 61 has a screw that transmits a driving force to the cantilever unit 35. The information processing device 20 may specify the amount of movement of the cantilever unit 35 as a value obtained by multiplying the number of applied pulses by the pitch of the screw.

[0037] Furthermore, the information processing device 20 can move the cantilever unit 35 by controlling the first motor 61 based on a command from the user to the input device 40. For example, when placing the sample S on the sample stage 14, the user inputs a command to raise the cantilever unit 35 to the input device 40. This causes the cantilever unit 35 to rise, increasing the space between the sample stage 14 and the cantilever 2 (probe 3), facilitating the task of placing the sample S on the sample stage 14 and improving user convenience.

[0038] The optical microscope 50 can be moved in the X-axis, Y-axis, and Z-axis directions by the driving force of the second motor 62. The information processing device 20 can control the second motor 62 by outputting a pulse signal to the second motor 62. The information processing device 20 can determine the amount of movement of the optical microscope 50 and the position of the optical microscope 50 based on the number of pulses of the pulse signal. The amount of movement of the optical microscope 50 is, for example, the amount of movement from the initial position of the optical microscope 50. The second motor 62 has a screw that transmits power to the optical microscope 50. The information processing device 20 may determine the amount of movement of the optical microscope 50 by multiplying the pitch of the screw by the number of applied pulses.

[0039] Furthermore, the information processing device 20 can move the optical microscope 50 by controlling the second motor 62 based on a command from the user to the input device 40 .

[0040] [Hardware Configuration of Information Processing Device] FIG. 2 is a diagram showing an example of the hardware configuration of information processing device 20. Referring to FIG. 2, information processing device 20 mainly includes a central processing unit (CPU) 160, a read-only memory (ROM) 162, a random access memory (RAM) 164, a hard disk drive (HDD) 166, a communication interface (I / F) 168, a display I / F 170, an input I / F 172, and a motor I / F 174. The components are interconnected via a data bus. Note that at least a portion of the hardware configuration of information processing device 20 may be located within measurement device 10. Alternatively, information processing device 20 may be configured as a separate entity from SPM 100 and configured to communicate bidirectionally with SPM 100.

[0041] The communication I / F 168 acquires information (voltage value Vz and deviation Sd) from the Z-direction drive unit 18. The communication I / F 168 also outputs the voltage value Vx and the voltage value Vy in the Y-axis direction to the XY-direction drive unit 16. The communication I / F 168 also acquires image data from the optical microscope 50. The display I / F 170 is an interface for communicating with the display device 30. The input I / F 172 is an interface for communicating with the input device 40. The motor I / F 174 is an interface for outputting pulse signals to the first motor 61 and the second motor 62.

[0042] The ROM 162 stores programs executed by the CPU 160. The RAM 164 can temporarily store data generated by the execution of the programs by the CPU 160 and data input via the communication I / F 168. The RAM 164 can function as a temporary data memory used as a work area. The HDD 166 is a non-volatile storage device. A semiconductor storage device such as a flash memory may be used instead of the HDD 166.

[0043] The program stored in ROM 162 may be stored in a non-transitory storage medium and distributed as a program product. Alternatively, the program may be provided by an information provider as a product program that can be downloaded via the Internet or the like. The information processing device 20 reads the program provided from a storage medium or the Internet or the like. The information processing device 20 stores the read program in a predetermined storage area (e.g., ROM 162). By executing the program, the CPU 160 can perform the image data acquisition process described below. The information processing device 20 is also referred to as a "control device" or a "control circuit."

[0044] [Example of functional configuration of information processing device] Fig. 3 is a functional block diagram showing the main functions of the information processing device 20. The information processing device 20 has a detection unit 102, an approach processing unit 104, and a storage unit 108. The first motor 61 corresponds to the "displacement mechanism" of the present disclosure. The displacement mechanism changes the relative position of the sample stage 14 and the cantilever 2 (cantilever unit 35) in the Z-axis direction. The approach processing by the approach processing unit 104 will be described later. The optical microscope 50, the detection unit 102, and the second motor 62 constitute a detection mechanism 110.

[0045] The number of pulses from the second motor 62 is input to the detection unit 102. As will be described later, the detection unit 102 acquires first information and second information based on the number of pulses of the second motor 62, and outputs the first information and second information to the approach processing unit 104. In this embodiment, the first information is information about the position of the cantilever 2 in the Z-axis direction. The second information is information about the position of the sample S in the Z-axis direction.

[0046] Furthermore, the detection unit 102 can detect the amount of movement of the cantilever 2 in the Z-axis direction based on the number of pulses from the first motor 61 .

[0047] The approach processing unit 104 controls the first motor 61 at an approach speed described below. Furthermore, the approach processing unit 104 determines a speed reduction position based on the first information and the second information. The speed reduction position is a position where the approach speed is switched from high to low. Furthermore, the approach processing unit 104 controls the first motor 61 so that the approach speed changes from high to low at the speed reduction position. The memory unit 108 stores a previous speed reduction position 108A described below. Furthermore, the memory unit 108 stores programs such as calculation formulas described below.

[0048] Data of an image captured by the optical microscope 50 (hereinafter also referred to as "image data") is input from the optical microscope 50 to the detection unit 102. The detection unit 102 may detect whether or not the image data is focused on the target object, as will be described later.

[0049] [Determining the Speed ​​Slowing Position] Next, a method for determining the speed slowing position will be described. In this embodiment, the focal length L3 of the optical microscope 50 is constant at least during the period in which the approach process is being performed.

[0050] The SPM 100 starts measuring the sample S when a predetermined start condition is met. The start condition includes the following first and second conditions. The first condition is met when a start operation is performed by the user on the input device 40. The second condition is met when the SPM 100 detects that the sample S to be measured has been placed.

[0051] As described above, to improve user convenience, the cantilever unit 35 including the cantilever 2 can be moved in the Z-axis direction by user operation or the like. In particular, since the cantilever unit 35 is moved upward to place the sample S on the sample stage 14, the cantilever 2 (probe 3) and the sample S may be far apart after the sample is placed. Therefore, when the above-described start condition is met, the SPM 100 of this embodiment executes the approach process. The approach process is a process of bringing the cantilever 2 closer to the sample S. The approach process is also referred to as an "approach operation." Furthermore, the speed at which the cantilever 2 (cantilever unit 35) is brought closer to the sample S during the approach process (approach period) is also referred to as the "approach speed."

[0052] More specifically, the approach process is a process of moving the cantilever 2 closer to the sample S while performing feedback control until a physical quantity (e.g., atomic force) that the cantilever 2 receives from the sample S reaches a specified value. When the physical quantity reaches the specified value, the information processing device 20 outputs a stop command to the measurement device 10. The specified value may be set by the user or may be a predetermined value. Note that in the approach process, a value corresponding to the physical quantity (e.g., the amount of deflection of the cantilever 2) may be used instead of the physical quantity itself.

[0053] In the approach process of this embodiment, the sample stage 14 is fixed, while the cantilever 2 is lowered. Furthermore, during the analysis of the sample S, the SPM 100 drives the sample stage 14 in the Z-axis direction using the Z-direction driver 18, and fixes the cantilever 2. As a modified example, during the analysis of the sample S, the SPM 100 may drive the cantilever 2 and fix the sample stage 14, or may drive both the cantilever 2 and the sample stage 14.

[0054] To shorten the approach process time, the information processing device 20 may increase the descent speed (approach speed) of the cantilever 2. However, if the descent speed of the cantilever 2 is too fast, even if the physical quantity reaches a specified value and the measurement device 10 receives a stop command from the information processing device 20, the cantilever 2 will stop after the stop command is received. This poses a risk of the cantilever 2 colliding with the sample S. In this case, there is a risk of damage to at least one of the probe 3 and the sample S. Conversely, if the approach speed is slowed down to prevent a collision between the cantilever 2 and the sample S, the approach process will take a long time.

[0055] Therefore, the SPM 100 of this embodiment determines a speed reduction position in order to shorten the approach process time and reduce collisions between the cantilever 2 and the sample S. The SPM 100 then lowers the cantilever unit 35 to the speed reduction position at a first speed, and when the cantilever unit 35 reaches the speed reduction position, lowers the cantilever unit 35 at a second speed. Here, the second speed is slower than the first speed. The first speed corresponds to "high speed" in this disclosure, and the second speed corresponds to "low speed" in this disclosure. For example, the first speed may be the maximum speed of the cantilever 2, and the second speed may be the minimum speed of the cantilever 2.

[0056] The SPM 100 can shorten the approach process time by lowering the cantilever 2 at high speed to the speed reduction position. Furthermore, since the cantilever 2 is lowered at a low speed after reaching the speed reduction position, the possibility of the cantilever 2 colliding with the sample S can be reduced even if the stopping of the cantilever 2 is delayed from the stop command of the feedback control.

[0057] 4 and 5 are diagrams for explaining a method for determining a speed reduction position in this embodiment. Fig. 4(A) is a diagram for explaining a method for acquiring first information, and Fig. 4(B) is a diagram for explaining a method for acquiring second information. Fig. 5 is a diagram for explaining a method for determining a speed reduction position based on the first information and the second information.

[0058] First, the information processing device 20 acquires image data from the optical microscope 50 while lowering the optical microscope 50. The detection unit 102 of the information processing device 20 detects whether the object is in focus in the image data. Then, if the detection unit 102 detects that the object is in focus, it stores the position of the optical microscope 50 at that time (the number of pulses of the second motor 62).

[0059] In this embodiment, the information processing device 20 repeats this process twice, and recognizes the position where the cantilever 2 is focused the first time after the cantilever starts to descend as information (first information) about the position of the cantilever 2. Then, the information processing device 20 recognizes the position where the cantilever 2 is focused the second time as information (second information) about the position of the sample S.

[0060] In this embodiment, the method of detecting whether or not the object is in focus is adopted, in which the detection unit 102 processes image data in real time and automatically performs the detection. As such a method, a conventionally known method can be appropriately adopted, for example, a contrast method.

[0061] This will be described in detail with reference to Fig. 4. Fig. 4(A) shows a state in which it is detected by a predetermined method (for example, the contrast method described above) that the object has been brought into focus for the first time after the optical microscope 50 has started to descend. The detection unit 102 acquires the number of pulses of the second motor 62 in this state as first information. This first information is information relating to the position of the cantilever 2 (reflecting member 2a) in the Z-axis direction.

[0062] When the detection unit 102 acquires the first information, the information processing device 20 executes a retraction process so that the detection light 50a from the optical microscope 50 does not strike the cantilever 2. This retraction process is, for example, a process of moving the cantilever 2 in at least one of the X-axis direction and the Y-axis direction. Thereafter, the information processing device 20 lowers the optical microscope 50 until the object is again in focus.

[0063] 4B is a diagram showing a state in which it is detected by a predetermined method that the object has been brought into focus for the first time after the retraction process has been performed. The detection unit 102 acquires the number of pulses of the second motor 62 at this point as second information. This second information is information regarding the position of the sample S (sample surface Sa) in the Z-axis direction. As described above, the detection unit 102 (detection mechanism 110) acquires the first information and the second information based on the detection by the optical microscope 50.

[0064] In the state shown in FIG. 4A, the distance between the lens of the optical microscope 50 and the reflecting member 2a of the cantilever 2 should be the focal length L3 of the optical microscope 50. Also, in the state shown in FIG. 4B, the distance between the lens of the optical microscope 50 and the reflecting member 2a on the sample surface Sa should be the focal length L3 of the optical microscope 50. Since the distance L3 is constant, as shown in FIG. 4A, the distances L1 and L2 are the same. The distance L1 is the distance the optical microscope 50 descends (see FIG. 4B). The distance L2 is the distance from the reflecting member 2a (more precisely, the point where the detection light strikes the reflecting member 2a) to the sample surface Sa. In other words, the distance L2 is the distance between the cantilever 2 and the sample S.

[0065] In this way, the approach processing unit 104 can calculate the distance L2 based on the difference between the "first information (the number of pulses of the second motor 62 when the cantilever is in focus)" and the "second information (the number of pulses of the second motor 62 when the sample surface is in focus)." For example, the approach processing unit 104 can calculate the distance L2 by subtracting the "second information" from the "first information" and converting the number of pulses into a movement amount.

[0066] The approach processing unit 104 determines the speed reduction position α based on the calculated distance L2, which will be described in detail with reference to FIG.

[0067] The distance L4 from the reflecting member 2a to the tip 3a of the probe 3 is a fixed value determined by the type of cantilever used. A fixed distance from the sample surface Sa is defined as distance L6. Distance L6 is the distance at which the cantilever 2 approaches the sample so that the physical quantity it receives from the sample S may reach a specified value, and is a fixed value determined by the user based on the properties and shape of the sample S. In other words, it is the distance between the sample and the cantilever at which it is desirable to start reducing the approach speed, and is, for example, 0.5 mm. Note that distances L4 and L6 may be changeable by the user.

[0068] The approach processing unit 104 calculates the distance L5 between the probe tip 3a and the sample surface Sa by subtracting the distance L4 from the distance L2. Furthermore, the approach processing unit 104 calculates the distance L7 by which the cantilever is moved at high speed by subtracting the distance L6 from the distance L5. That is, the approach processing unit 104 calculates the distance L7 using the following formula (1):

[0069] L7=L2-L4-L6 (1) Here, the distance L2 on the right side of equation (1) is the same as the distance L1, which is the lowering distance of the optical microscope 50. Furthermore, the distances L4 and L6 on the right side of equation (1) are fixed values. Therefore, the sum M of the distances L4 and L6 is also a fixed value. In other words, the distance L7 can also be expressed by the following equation (2).

[0070] L7 = L1 - M1 (2) In this way, the approach processing unit 104 can calculate the distance L5 between the probe tip 3a and the sample surface Sa based on the first information and the second information. Furthermore, the distance L7 by which the cantilever is moved at high speed can be calculated from the distance L5 and a pre-stored fixed value. In other words, the speed reduction position α at which the approach speed of the cantilever 2 (cantilever unit 35) is reduced can be determined. The approach processing unit 104 then controls the first motor 61 so that the cantilever 2 and the sample S approach each other and the approach speed is reduced at the speed reduction position α.

[0071] That is, the approach processing unit 104 moves the cantilever 2, which is currently positioned (the position of the cantilever 2 shown in FIG. 5 ), a distance L7 at a first speed (high speed). After moving the distance L7, the approach speed of the cantilever 2 is changed to a second speed (low speed) on the assumption that the cantilever 2 has reached the speed reduction position α. ​​The cantilever 2 is then moved further until the physical quantity received from the sample S reaches a specified value. This control allows the cantilever 2 to move at high speed from the initial position to the speed reduction position α and then at a low speed from the speed reduction position α. ​​As a result, the SPM 100 can perform the approach operation in a short time while reducing the risk of the cantilever 2 coming into contact with the sample surface Sa.

[0072] While the distance L6 between the speed reduction position α and the sample surface is a fixed value, the distance L7 between the tip 3a of the probe and the speed reduction position α could not be determined with conventional technology because it differs depending on the height of the cantilever 2 at any given time. Even if the absolute value of the height of the cantilever 2 could be determined, the height of the sample surface on which it is placed is unknown, so the distance L7 could not be determined.

[0073] In this embodiment, the distance L7 can be determined based on the first information and the second information calculated by the optical microscope 50. It should be noted that the distance between the sample surface and the cantilever 2 is calculated, and there is no need to calculate the absolute values ​​of the heights of the sample surface and the cantilever.

[0074] In this embodiment, the second information is information indicating the position of the sample surface Sa in the Z-axis direction. Therefore, the detection mechanism 110 detects the sample surface Sa, and the information processing device 20 can acquire the second information.

[0075] Furthermore, the focal length L3 of the optical microscope 50 is constant at least during the period in which the approach process is being performed, and therefore the processing load of the optical microscope 50 can be reduced compared to a configuration in which the focal length L3 of the optical microscope 50 is variable.

[0076] Furthermore, in this embodiment, the reflecting member 2 a of the cantilever 2 used to measure the sample can also be used to acquire the first information. Therefore, compared to an SPM in which the reflecting member used to measure the sample and the reflecting member used to acquire the first information are separate, the SPM 100 of this embodiment can reduce the number of parts.

[0077] Furthermore, in this embodiment, the optical microscope 50 that displays image data during periods other than the approach period can be used as a common optical microscope 50 for acquiring the first information and the second information. Therefore, compared to an SPM in which the optical microscope that displays the detected image and the optical microscope that acquires the first information and the second information are separate, the scanning probe microscope of the present disclosure can reduce the number of parts.

[0078] 6 is a flowchart showing the processing flow of the SPM 100 of this embodiment. The flowchart in Fig. 6 starts when the above-mentioned start condition is met. First, in step S102, the SPM 100 acquires first information (information about the position of the cantilever in the Z-axis direction) (see Fig. 4A).

[0079] Next, in step S104, the SPM 100 acquires second information (information regarding the position of the sample surface Sa in the Z-axis direction) (see FIG. 4B). Next, in step S106, the SPM 100 determines a speed reduction position α (see FIG. 5). Next, in step S108, the SPM 100 executes an approach process based on the speed reduction position α. ​​Then, after the approach process is completed, in step S110, the SPM 100 starts measuring the sample S.

[0080] [Previous Speed ​​Slowing Position] Next, the previous speed slowing position 108A in Fig. 3 will be described. There are cases where the thickness of the sample S to be measured this time is the same or approximately the same as the thickness of the sample S measured previously. In such cases, the speed slowing position α for the previous measurement and the current measurement will be the same. Therefore, in cases such as when the user recognizes that the thickness of the sample S to be measured this time is the same or approximately the same as the thickness of the sample S measured previously, it is preferable that the information processing device 20 use the speed slowing position α determined previously as the speed slowing position α for the current measurement.

[0081] When the information processing device 20 determines the speed reduction position α, it stores it as the previous speed reduction position 108 A. Furthermore, the user can select whether or not to use the previous speed reduction position 108 A as the current speed reduction position.

[0082] 7 is a diagram showing an example of a mode setting screen. This mode setting screen is displayed in the display area 30A of the display device 30 when the above-mentioned start condition is met. In the example of FIG. 7, the modes of the SPM 100 include a normal mode and a same as previous mode. In the example of FIG. 7, a character image 41 for the normal mode, a character image 43 for the same as previous mode, and an OK button 44 are displayed.

[0083] The user can select (set) a desired mode by inputting a command on the mode setting screen of Fig. 7. In the example of Fig. 7, the mode is set by selecting the radio button corresponding to the desired mode and operating the OK button 44. The mode setting is realized, for example, by storing a mode flag indicating the mode in a predetermined storage area.

[0084] When the normal mode is set by the user, the information processing device 20 determines the speed reduction position α by the process in Fig. 6. A case where the same mode as the previous time was set by the user will be described.

[0085] The information processing device 20 stores in advance the distance by which the user raised the cantilever 2 after the previous measurement (the value obtained by converting the number of pulses of the first motor into a distance). Since this distance corresponds to L5 (the current distance between the tip of the cantilever and the sample surface), distance L7 can be calculated by subtracting L6, which was used previously, from L5.

[0086] With this configuration, the cantilever 2 can be moved based on the previously determined speed reduction position, thereby reducing the process of lowering the optical microscope 50 and the process performed on the image data acquired by the optical microscope 50.

[0087] Second Embodiment Next, a second embodiment will be described. For example, the sample S may have a characteristic that makes it impossible to focus the optical microscope 50. This characteristic is a characteristic that does not have a certain level of contrast, such as the sample surface Sa being black. In such a case, it may be impossible to focus the optical microscope 50 on the sample S, and it may be impossible to determine the speed reduction position α. ​​Therefore, in the second embodiment, a configuration will be described that makes it possible to determine the speed reduction position α even when the optical microscope 50 cannot focus on the sample S.

[0088] The placement surface 14a in the second embodiment is a reflective member. This reflective member is, for example, a mirror. Because the placement surface 14a is a reflective member in this way, the SPM 100 can focus the optical microscope 50 on the placement surface 14a. Therefore, the detection mechanism 110 can obtain the position of the placement surface 14a in the Z-axis direction as second information.

[0089] In other words, in the second embodiment, the information processing device 20 recognizes the position of the object on which the optical microscope 50 focuses the first time after starting to descend as the position of the cantilever 2 (first information), and recognizes the position of the object on which the optical microscope 50 focuses the second time as the position of the placement surface 14a (second information).

[0090] Furthermore, if the sample S is present at a position where the optical microscope 50 is focused, the detection mechanism 110 cannot detect the placement surface 14a due to the obstruction caused by the sample S. Therefore, in the second embodiment, the SPM 100 executes a predetermined process to enable the detection mechanism 110 to detect the position of the placement surface 14a. The predetermined process in this embodiment is, for example, a process of moving the sample stage 14 a predetermined distance in a predetermined direction on the XY plane. This process allows the sample S to be evacuated, and as a result, the detection mechanism 110 can detect the placement surface 14a (can acquire second information). This predetermined process is also referred to as a "sample S evacuation process." Furthermore, when the placement surface 14a is detected, the SPM 100 moves the sample stage 14 so that the sample S returns to its original position.

[0091] Furthermore, in this embodiment, the thickness of the sample S is used to determine the speed reduction position α. ​​The thickness of the sample S is input, for example, by the user. FIG. 8 shows an example of an input screen on which the thickness of the sample is input. For example, this input screen is displayed in the display area 30A of the display device 30 when the above-mentioned start condition is met. In the example of FIG. 8, an input area 45 is displayed. The user inputs the thickness of the sample in the input area 45.

[0092] 9 and 10 are diagrams for explaining the method of determining the speed reduction position in this embodiment. Note that FIGS. 9 and 10 show the state after the evacuation process of the sample S has been executed. Similar to FIG. 4A, FIG. 9A shows that the information processing device 20 has acquired first information (information about the position of the cantilever 2 in the Z-axis direction). Furthermore, FIG. 9B shows that the information processing device 20 has acquired second information (information about the position of the placement surface 14a in the Z-axis direction).

[0093] 9(A) and 9(B), the distance L3 (the focal length of the optical microscope 50) is constant. Therefore, as shown in FIG. 9(A), the distance L11 and the distance L12 are the same. The distance L11 is the distance the optical microscope 50 is lowered (see FIG. 9(B)). The distance L12 is the distance from the reflecting member 2a (more precisely, the point on the reflecting member 2a where the detection light strikes) to the placement surface 14a. In other words, the distance L12 is the distance between the cantilever 2 and the placement surface 14a.

[0094] 10, the approach processing unit 104 determines the speed reduction position α based on the distance L12. As shown in FIG. 10, the thickness of the sample is set to a distance L18. Here, the thickness of the sample (distance L18) is an input value input in advance by the user to the input screen of FIG. 8.

[0095] The approach processing unit 104 calculates distance L15 by subtracting distance L4 from distance L12. Distance L15 is the distance between the probe tip 3a and the placement surface 14a. Furthermore, the approach processing unit 104 calculates distance L17 by subtracting distance L6 and distance L18 from distance L15. That is, the approach processing unit 104 calculates distance L17 using the following equation (3):

[0096] L17=L12-L4-L6-L18 (3) Here, the distance L12 on the right side of equation (3) is the same as the distance L11, which is the lowering distance of the optical microscope 50. Furthermore, the distances L4 and L6 on the right side of equation (3) are the above-mentioned total value M. In other words, the distance L17 can also be expressed by the following equation (4).

[0097] L17=L11-L18-M1 (4) Fig. 11 is a flowchart showing the processing flow of the information processing device 20 of this embodiment. In Fig. 11, the processing of steps S120 and S122 is added before step S102 in Fig. 6, and step S104 is replaced with step S124.

[0098] When the above-described start condition is met, in step S120, the information processing device 20 executes the evacuation process of the sample S. Next, in step S122, the information processing device 20 acquires the thickness of the sample S input by the user (see FIG. 8).

[0099] After the process of step S102 is completed, the information processing device 20 acquires second information (the position of the sample stage 14 in the Z-axis direction) in step S124. Thereafter, the information processing device 20 executes the process of step S106.

[0100] In this way, the information processing device 20 of this embodiment can determine the speed reduction position α based on the first information, the second information, and the thickness of the sample (distance L18), even if the sample S has characteristics that prevent the optical microscope 50 from focusing on the sample S.

[0101] Furthermore, the information processing device 20 executes a process (predetermined process) for evacuating the sample S (step S120). Therefore, even if the sample S is located in a position that prevents the information processing device 20 from acquiring the second information, the information processing device 20 can acquire the second information.

[0102] The retraction process of the sample S is a process of moving the sample stage 14 in the XY plane. Therefore, the SPM 100 can realize the retraction process of the sample S by a relatively simple process.

[0103] <Modifications> (1) In the above embodiment, the SPM 100 is configured to move (lower) the cantilever 2 without moving the sample stage 14 (the sample stage 14 is fixed) during the approach process. However, a configuration may be adopted in which the cantilever 2 is moved (raised) without moving the cantilever 2 (the cantilever 2 is fixed) during the approach process. In this configuration, the SPM 100 determines the speed reduction position α based on the distance L2 or the distance L12, etc. Then, the SPM 100 moves (raises) the sample stage 14 at a third speed up to the speed reduction position α, and then moves (raises) the sample stage 14 at a fourth speed (a speed slower than the third speed) after the sample stage 14 reaches the speed reduction position α.

[0104] Furthermore, the SPM 100 may move (lower) the cantilever 2 and move (raise) the sample stage 14 during the approach process. In this case, the speed reduction position of the cantilever 2 (hereinafter referred to as the "first speed reduction position α1") and the speed reduction position of the sample stage 14 (hereinafter referred to as the "second speed reduction position α2") are determined based on the distance L2 or the distance L12. Then, during the approach process, the SPM 100 moves (lowers) the cantilever 2 at a first speed to the first speed reduction position α1, and moves (lowers) the sample stage 14 at a second speed once the cantilever 2 reaches the first speed reduction position α1. Furthermore, the SPM 100 moves (raises) the sample stage 14 at a third speed to the second speed reduction position α2, and moves (raises) the sample stage 14 at a fourth speed once the sample stage 14 reaches the second speed reduction position α2. In other words, the first motor 61 is a displacement mechanism that changes the relative position in the Z-axis direction between the sample stage 14 and the cantilever 2. The above-mentioned approach speed is the speed at which the relative position is changed. An SPM employing such a configuration can achieve the same effects as the above-mentioned SPM.

[0105] (2) In the above embodiment, the first information is the position of the reflecting member 2 a of the cantilever 2 in the Z-axis direction. However, the first information may be any other part of the cantilever 2. For example, the first information may be the position of the probe 3 in the Z-axis direction.

[0106] (3) In the above-described embodiment, the optical microscope 50 is exemplified as the detection device that detects the first information and the second information. However, the detection device may be another device. The other device may be, for example, a camera or a microscope related to the optical microscope 50 (for example, an electron microscope).

[0107] (4) In the above embodiment, the focal length of the optical microscope 50 is constant during the approach period. However, it may be variable as long as the approach processing unit 104 can recognize the focal length of the optical microscope 50. When such a configuration is adopted, the first information and the second information may be recognized, for example, by changing the focal length. That is, the focal length of the optical microscope 50 is gradually increased, and the focal length when the microscope is first focused is recognized as L3. The focal length when the microscope is second focused is recognized as L1 + L3. By subtracting these values, the distance L2 (= L1) between the cantilever 2 and the sample surface can be recognized.

[0108] When such a configuration is employed, for example, the information processing device 20 can acquire the first information and the second information while keeping the optical microscope 50 fixed. Therefore, the process of moving the optical microscope 50 can be reduced.

[0109] Furthermore, after the optical microscope 50 acquires the first information, the focal length for acquiring the second information may be calculated by adding a predetermined value to the focal length used when the first information was acquired. The information processing device 20 determines whether the second information can be acquired using the calculated new focal length. If the information processing device 20 is unable to acquire the second information due to out-of-focus conditions, it drives the optical microscope 50 to acquire the second information. With this configuration, the travel distance of the optical microscope 50 can be reduced.

[0110] (5) In the above embodiment, a configuration has been described in which the optical microscope 50 automatically adjusts the focus. However, a configuration in which a user manually adjusts the focus of the optical microscope 50 may also be employed. For example, the information processing device 20 may detect at least one of the position of the cantilever 2 in the Z-axis direction, the position of the sample surface Sa in the Z-axis direction, and the position of the placement surface 14a in the Z-axis direction through manual focusing by the user.

[0111] (6) In the above embodiment, the predetermined process for the detection mechanism 110 to acquire the second information is described as a process of moving the sample stage 14 to evacuate the sample S (see step S120 in FIG. 11 , etc.). However, the predetermined process may be another process. For example, the predetermined process may be a process of moving the optical microscope 50 a predetermined distance in a predetermined direction on the XY plane.

[0112] Alternatively, the optical microscope 50 may be lowered until the structure (sample stage) behind the cantilever 2 is brought into focus while the cantilever 2 is within the field of view. In this case, the SPM 100 does not need to retract the cantilever 2.

[0113] Alternatively, the speed reduction position α may be determined before the sample S having the above-described characteristics is placed. For example, the information processing device 20 lowers the optical microscope 50 before the sample S is placed. Then, the information processing device 20 recognizes the object that comes into focus the first time after the optical microscope 50 starts to descend as the position of the cantilever 2 (first information), and the object that comes into focus the second time as the position of the sample S (second information). The information processing device 20 then acquires the thickness of the sample S by displaying the input screen shown in FIG. 8 . The information processing device 20 determines the speed reduction position α based on the first information, the second information, and the thickness of the sample S. After the speed reduction position α is determined, the information processing device 20 executes a prompt notification to prompt the user to place the sample S on the sample stage 14. The prompt notification is, for example, a process of displaying a text image such as "Please place the sample" on the display device 30. Once the sample S is placed and the user performs a start operation, the information processing device 20 executes the approach process. With this configuration, the speed reduction position α can be determined without performing a predetermined process.

[0114] (7) In the examples of Figures 4 and 9, the optical microscope 50 is shown as a simplified rectangle. In the examples of Figures 4 and 9, the distance between the optical microscope 50 and the detection object (the reflective member 2a of the cantilever 2, the sample surface Sa) is the distance between the bottom side of the rectangle and the detection object. However, this distance may also be the distance between a predetermined member of the optical microscope 50 and the detection object. The predetermined member may be, for example, an optical system (lens) included in the optical microscope 50.

[0115] Aspects It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0116] (Item 1) A scanning probe microscope according to the present disclosure includes a sample stage, a cantilever, a displacement mechanism, a detection mechanism, and an approach processing unit. A sample is placed on the sample stage. The cantilever is scanned along the surface of the sample. The displacement mechanism changes the relative position of the sample stage and the cantilever in the thickness direction of the sample. The detection mechanism acquires first information, which is information about the position of the cantilever in the thickness direction, and second information, which is information about the position of the sample in the thickness direction or the position of the sample stage in the thickness direction. The approach processing unit controls the displacement mechanism at a predetermined approach speed so that the sample stage and the cantilever approach each other. Based on the first information and the second information, the approach processing unit determines a speed reduction position at which the approach speed is switched from high to low. The approach processing unit also controls the displacement mechanism so that the approach speed is switched from high to low at the speed reduction position.

[0117] With this configuration, the scanning probe microscope detects not only the second information, which is the position of the sample or the position of the sample stage, but also the first information about the cantilever. Based on the first information and the second information, the scanning probe microscope can determine the speed reduction position where the approach speed is switched from high to low. Therefore, even if the cantilever is movable in the thickness direction of the sample, the speed reduction position can be appropriately determined, allowing the approach operation to be performed in a short time while reducing the risk of the cantilever coming into contact with the sample surface.

[0118] (Item 2) In the scanning probe microscope according to item 1, the second information is information indicating the position of the surface of the sample in the thickness direction.

[0119] According to this configuration, the detection mechanism can detect the second information by detecting the surface of the sample.

[0120] (Item 3) In the scanning probe microscope according to item 1, the sample stage has a placement surface on which the sample is placed. The second information is information indicating the position of the placement surface in the thickness direction. The approach processing unit accepts input of thickness information indicating the thickness of the sample from a user. The approach processing unit determines a speed reduction position based on the first information, the second information, and the thickness information.

[0121] With this configuration, the second information can be obtained even when the detection mechanism cannot detect the surface of the sample.

[0122] (4) In the scanning probe microscope according to the third aspect, the detection mechanism executes a predetermined process to acquire the second information. The detection mechanism acquires the second information after the predetermined process has been executed.

[0123] According to this configuration, even if the detection mechanism cannot be obtained due to obstruction of the sample, the second information indicating the position of the placement surface can be obtained by executing a predetermined process.

[0124] (Item 5) In the scanning probe microscope according to item 4, the predetermined process includes a process of moving the sample stage.

[0125] According to this configuration, the second information can be acquired by the relatively simple process of moving the sample stage.

[0126] (Item 6) In the scanning probe microscope according to any one of items 1 to 5, the detection mechanism includes an optical microscope with a fixed focal length. The cantilever is disposed between the optical microscope and a sample stage in the thickness direction. The scanning probe microscope moves the optical microscope in the thickness direction. The detection mechanism acquires first information based on the position of the optical microscope where the distance between the cantilever and the optical microscope is the focal length. The detection mechanism acquires second information based on the position of the optical microscope where the distance between the sample or the sample stage and the optical microscope is the focal length.

[0127] According to this configuration, the first information and the second information can be obtained using a microscope that has a relatively simple configuration.

[0128] (Item 7) In the scanning probe microscope according to item 6, the cantilever has a reflecting member formed on the side opposite to the portion facing the sample. The cantilever is displaced so that a physical quantity acting between the cantilever and the sample remains constant. The scanning probe microscope further includes a light source that irradiates the reflecting member with light. The scanning probe microscope measures the sample based on light reflected by the reflecting member. The detection mechanism acquires the first information based on the position of the optical microscope where the distance between the reflecting member and the optical microscope is the focal length.

[0129] With this configuration, the reflective member used for measuring the sample and the reflective member used for acquiring the first information can be used as a common reflective member, and therefore the scanning probe microscope of the present disclosure can reduce the number of parts compared to a scanning probe microscope in which the reflective member used for measuring the sample and the reflective member used for acquiring the first information are separate.

[0130] (Item 8) The scanning probe microscope according to any one of Items 1 to 5, further comprising a storage device that stores a previously determined speed reduction position. The approach processing unit controls the displacement mechanism so that the approach speed is changed from high to low at the speed reduction position previously stored in the storage device.

[0131] According to this configuration, the displacement mechanism can be controlled based on the previously determined speed reduction position, so that the process of determining the speed reduction position can be reduced.

[0132] (Item 9) In a scanning probe microscope described in any one of Items 1 to 5, the approach processing unit controls the displacement mechanism by performing feedback control until the physical quantity acting between the cantilever and the sample reaches a specified amount.

[0133] According to this configuration, the displacement mechanism can be controlled by a relatively simple process. (Item 10) In the scanning probe microscope according to any one of Items 1 to 5, the cantilever moves in the thickness direction independently of the sample stage.

[0134] This configuration can improve user convenience when placing a sample on the sample stage.

[0135] (Item 11) A control method according to the present disclosure is a method for controlling a scanning probe microscope. The scanning probe microscope includes a sample stage on which a sample is placed and a cantilever that scans along the surface of the sample. The relative position of the sample stage and the cantilever in the thickness direction of the sample is changed. The control method includes acquiring first information related to the position of the cantilever in the thickness direction and second information related to the position of the sample in the thickness direction or the position of the sample stage in the thickness direction. The control method includes changing the relative position at a predetermined approach speed so that the sample stage and the cantilever approach each other. The control method includes determining, based on the first information and the second information, a speed reduction position at which the approach speed is switched from high to low. Changing the relative position includes changing the relative position so that the approach speed is switched from high to low at the speed reduction position.

[0136] With this configuration, the scanning probe microscope detects not only the second information, which is the position of the sample or the position of the sample stage, but also the first information about the cantilever. Based on the first information and the second information, the scanning probe microscope can determine the speed reduction position where the approach speed is switched from high to low. Therefore, even if the cantilever is movable in the thickness direction of the sample, the speed reduction position can be appropriately determined, allowing the approach operation to be performed in a short time while reducing the risk of the cantilever coming into contact with the sample surface.

[0137] It should be noted that, with regard to the above-mentioned embodiments and modified examples, it has been intended from the outset of the application that the configurations described in the embodiments may be appropriately combined, including combinations not mentioned in the specification, to the extent that no inconvenience or contradiction arises.

[0138] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0139] 1 Optical system, 2 Cantilever, 2a Reflecting member, 3 Needle, 3a Tip, 4 Holder, 5 Beam splitter, 6 Laser light source, 7 Reflecting mirror, 8 Photodetector, 10 Measuring device, 12 Fine movement mechanism, 14 Sample stage, 14a Placement surface, 20 Information processing device, 22 Feedback signal generating unit, 30 Display device, 30A Display area, 35 Cantilever unit, 40 Input device, 45 Input area, 50 Optical microscope, 50a Detection light, 61 First motor, 62 Second motor, 102 Detection unit, 104 Approach processing unit, 108 Memory unit, 108A Previous speed reduction position, 110 Detection mechanism, 162 ROM, 164 RAM.

Claims

1. A sample stage having a placement surface on which a sample is placed; a cantilever that is scanned along a surface of the sample; a displacement mechanism for changing a relative position between the sample stage and the cantilever in a thickness direction of the sample; a detection mechanism that acquires first information that is information about a position of the cantilever in the thickness direction and second information that is information indicating a position of the placement surface in the thickness direction; an approach processing unit that controls the displacement mechanism at a predetermined approach speed so that the sample stage and the cantilever approach each other; The approach processing unit includes: receiving an input of thickness information indicating a thickness of the sample from a user; determining a speed reduction position at which the approach speed is switched from a high speed to a low speed based on the first information, the second information, and the thickness information; The scanning probe microscope controls the displacement mechanism so that the approach speed changes from a high speed to a low speed at the speed reduction position.

2. the scanning probe microscope executes a predetermined process for the detection mechanism to acquire the second information; The scanning probe microscope according to claim 1 , wherein the detection mechanism acquires the second information after the predetermined process is executed.

3. 3. The scanning probe microscope according to claim 2, wherein the predetermined process includes a process of moving the sample stage.

4. the detection mechanism includes an optical microscope having a fixed focal length; the cantilever is disposed between the optical microscope and the sample stage in the thickness direction, The scanning probe microscope moves the optical microscope in the thickness direction, The detection mechanism includes: acquiring the first information based on a position of the optical microscope where a distance between the cantilever and the optical microscope is the focal length; 4. A scanning probe microscope according to claim 1, wherein the second information is acquired based on a position of the optical microscope where a distance between the sample or the sample stage and the optical microscope is the focal length.

5. The cantilever is a reflecting member is formed on the opposite side of the portion facing the sample, a displacement such that a physical quantity acting between the cantilever and the sample becomes constant; The scanning probe microscope further includes a light source that irradiates the reflecting member with light, the scanning probe microscope measures the sample based on the light reflected by the reflecting member; 5. The scanning probe microscope according to claim 4, wherein the detection mechanism acquires the first information based on a position of the optical microscope at which a distance between the reflecting member and the optical microscope becomes the focal length.

6. The scanning probe microscope further includes a storage device that stores the previously determined speed reduction position, 4. The scanning probe microscope according to claim 1, wherein the approach processing unit controls the displacement mechanism so that the approach speed is changed from a high speed to a low speed at the speed reduction position previously stored in a storage device.

7. 4. The scanning probe microscope according to claim 1, wherein the approach processing unit controls the displacement mechanism by executing feedback control until a physical quantity acting between the cantilever and the sample reaches a specified amount.

8. 4. The scanning probe microscope according to claim 1, wherein the cantilever moves in the thickness direction independently of the sample stage.

9. 1. A method for controlling a scanning probe microscope, comprising: The scanning probe microscope comprises: a sample stage having a placement surface on which a sample is placed; a cantilever that is scanned along a surface of the sample; The relative position between the sample stage and the cantilever in the thickness direction of the sample is changed, The control method includes: Obtaining first information regarding a position of the cantilever in the thickness direction and second information indicating a position of the placement surface in the thickness direction; changing the relative position at a predetermined approach speed so that the sample stage and the cantilever approach each other; receiving an input of thickness information indicating a thickness of the sample from a user; determining a speed reduction position at which the approach speed is switched from a high speed to a low speed based on the first information, the second information, and the thickness information; The control method, wherein changing the relative position includes changing the relative position such that the approach speed at the speed reduction position changes from a high speed to a low speed.