JP7625971B2 - Scanning probe microscope and control method - Google Patents

Description

This disclosure relates to a scanning probe microscope and a control method.

Conventionally, a scanning probe microscope (SPM) equipped with a probe that moves relatively along the surface of a sample has been proposed. For example, the SPM described in JP 2021-004859 A (Patent Document 1) includes a control device, a sample stage on which a sample is placed, and a probe that moves relatively along the surface of the sample. The SPM measures the sample by driving the sample stage in the X-axis, Y-axis, and Z-axis directions. In addition, the control device performs feedback control so that the physical quantity (e.g., atomic force) acting between the probe and the sample is constant.

JP 2021-004859 A

During measurement of a sample by the SPM described above, even if the feedback control described above is performed, there are cases where the physical quantity acting between the probe and the sample does not remain constant. This is the case, for example, when the sample has a convex portion that is too large to be measured by the SPM. If the measurement is continued while the convex portion is present on the sample, there is a possibility that an inaccurate measurement result will be obtained.

This invention was made to solve these problems, and aims to provide a technique that reduces the occurrence of inaccurate measurement results even when the physical quantity acting between the probe and the sample is not constant.

The scanning probe microscope of the present disclosure measures a sample. The scanning probe microscope is a scanning probe microscope that includes a sample stage on which the sample is placed, a probe placed facing the sample, a first drive mechanism that moves the probe relatively along the surface of the sample by executing a first control so that a physical quantity acting between the probe and the sample becomes constant, and a control device that stops the measurement of the sample if the physical quantity does not become constant despite the execution of the first control.

The control method disclosed herein is a method for controlling a scanning probe microscope. The scanning probe microscope comprises a sample stage on which a sample is placed, a probe placed facing the sample, and a first drive mechanism for relatively moving the probe along the surface of the sample. The control method comprises executing a first control such that a physical quantity acting between the probe and the sample becomes constant, and stopping measurement of the sample if the physical quantity does not become constant despite the execution of the first control.

According to the present disclosure, even if control is performed so that the physical quantity acting between the probe and the sample is constant, if the physical quantity does not become constant, the measurement of the sample is stopped. Therefore, according to the present disclosure, it is possible to reduce the acquisition of inaccurate measurement results.

FIG. 1 is a diagram illustrating a schematic configuration of an SPM according to an embodiment. FIG. 2 is a diagram illustrating an example of a hardware configuration of an information processing device. FIG. 13 is a diagram showing an example of a measurement range. FIG. 2 is a functional block diagram of an information processing device. FIG. 13 is a diagram showing a method for detecting the occurrence of thermal drift. FIG. 13 is a diagram showing a second control in a case where an excessively large uneven portion is present on the sample. 4 is a flowchart for explaining an operation method of the SPM. 13 is a flowchart for explaining an operation method of the SPM according to the third embodiment. 11 shows an example of a notification message displayed on the display device. 13 shows an example of a notification message displayed in a display area of a display device. 13 is an example of a mode selection screen. FIG. 13 is a diagram for explaining a method for predicting a waiting time. FIG. 1 is a diagram for explaining thermal drift. 13 is a flowchart for explaining an operation method of the SPM of the modified example. 13 is a flowchart of a waiting time calculation process.

The following describes in detail an embodiment of the present invention with reference to the drawings. Note that the same or corresponding parts in the drawings are given the same reference numerals and their description will not be repeated.

[First embodiment]
FIG. 1 is a diagram showing a schematic configuration of a scanning probe microscope (SPM) according to an embodiment. A scanning probe microscope 100 according to the present embodiment is typically an atomic force microscope (AFM) that measures the shape of the surface of a sample S by utilizing a physical quantity acting between a probe (needle) 3 and the surface of the sample S. The present disclosure can be similarly applied to other scanning probe microscopes, for example, a scanning tunneling microscope (STM). The physical quantity is, for example, an atomic force (attractive or repulsive force). In the following, the height direction of the sample S is the Z-axis direction, and the directions perpendicular to the Z-axis direction are the X-axis direction and the Y-axis direction.

As shown in FIG. 1, the scanning probe microscope 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, a coarse movement mechanism 13, an XY direction drive unit 16, a Z direction drive unit 18, and a feedback signal generating unit 22. The "fine movement mechanism 12" in this embodiment corresponds to the "first drive mechanism" in this disclosure, and the "coarse movement mechanism 13" in this embodiment corresponds to the "second drive mechanism" in this disclosure.

The sample S is placed on the sample stage 14. 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. 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 drive unit 16. The Z scanner 12z has a piezoelectric element that expands and contracts in response to a voltage applied from the Z direction drive unit 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 a configuration having a piezoelectric element.

In this embodiment, when the voltage applied by the Z-direction driving unit 18 is the maximum value Vmax, the sample stage 14 is driven to the highest position in the Z-axis direction. When the voltage applied by the Z-direction driving unit 18 is the minimum value Vmin, the sample stage 14 is driven to the lowest position in the Z-axis direction. For example, the maximum value Vmax is +V1 (V1 is a positive real number), and the minimum value Vmin is -V1. When the voltage applied by the Z-direction driving unit 18 is 0, the sample stage 14 is driven to the initial position. In this embodiment, the initial position is the center position in the Z-axis direction. As a modified example, when the voltage applied by the Z-direction driving unit 18 is the maximum value Vmax, the sample stage 14 may be driven to the lowest position in the Z-axis direction, and when the voltage is the minimum value Vmin, the sample stage 14 may be driven to the highest position in the Z-axis direction.

The cantilever 2 is formed in the shape of a leaf spring, one end of which is supported by a holder 4. The other end of the cantilever 2 is a free end, and is arranged to face the sample S. In the example shown in FIG. 1, it is arranged upward in the Z-axis direction. The cantilever 2 has a front surface that faces the sample S, and a back surface opposite the front surface. A probe 3 is arranged on the surface of the tip of the free end of the cantilever 2 so as to face the sample S. The back surface of the tip is configured to reflect light. The tip of the cantilever 2 is displaced in the Z-axis direction by a physical quantity (e.g., atomic force) acting between the probe 3 and the sample S.

An optical system 1 is provided above the cantilever 2 in the Z-axis direction to detect the amount of deflection of the cantilever 2 (i.e., the amount of displacement of the tip). When measuring the sample S, the optical system 1 irradiates the back surface (reflecting surface) of the cantilever 2 with laser light and detects the laser light 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.

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 back surface (reflection surface) of the cantilever 2. The laser light reflected by the back surface of the cantilever 2 is further reflected by the reflector 7 and enters the photodetector 8.

The photodetector 8 has a light receiving surface that is divided into multiple (e.g., 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 direction and the Y-axis direction. When the tip of the cantilever 2 is displaced in the Z-axis direction, the ratio of the amount of light irradiated to the multiple light receiving surfaces changes, and the amount of deflection (displacement) of the cantilever 2 can be detected based on the multiple amounts of light received.

The feedback signal generating unit 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 generating unit 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 referred to as "feedback control". The feedback control corresponds to the "first control" of this disclosure. Specifically, the feedback signal generating unit 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 generating unit 22 calculates a voltage value Vz for displacing the Z scanner 12z corresponding to this control amount. The feedback signal generating unit 22 outputs a voltage signal indicating the voltage value Vz to the Z direction driving unit 18. The Z direction driving unit 18 applies the voltage value Vz to the Z scanner 12z. In this way, the Z-direction drive unit 18 accepts the input of a voltage value from the feedback signal generator 22 and applies a voltage based on that voltage value to the Z scanner 12z.

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

The coarse movement mechanism 13 moves the sample stage 14 in the X-axis direction, the Y-axis direction, and the Z-axis direction. Furthermore, in the X-axis direction, the Y-axis direction, and the Z-axis direction, the first movement range of the sample stage 14 by the fine movement mechanism 12 is configured to be smaller than the second movement range of the sample stage 14 by the coarse movement mechanism 13. Furthermore, due to causes described below, the SPM 100 may not be able to properly measure the sample S. In this case, the coarse movement mechanism 13 executes a retraction process under the control of the information processing device 20. The retraction process is a process for increasing the distance between the probe 3 and the sample stage 14. The coarse movement mechanism 13 is driven by the information processing device 20.

The information processing device 20 mainly controls the operation of the measuring device 10. Measurement data indicating the amount of feedback in the Z-axis direction (applied voltage Vz to the Z scanner 12z and deviation Sd) is sent from the Z-axis driving unit 18 to the information processing device 20. The measurement data is transmitted for each measurement point determined at a predetermined interval in the Y-axis direction of the sample S (see FIG. 3). The information processing device 20 stores the measurement data. The information processing device 20 calculates the amount of displacement of the sample S in the Z-axis direction from the voltage Vz based on correlation information indicating the relationship between the voltage Vz stored in advance and the corresponding amount of displacement of the sample S (sample stage 14) in the Z-axis direction. The calculated amount of displacement is a value reflecting a value indicating the position of the sample S in the Z-axis direction (hereinafter also referred to as the "Z value"). The information processing device 20 creates two-dimensional or three-dimensional measurement data representing the shape of the surface of the sample S by calculating the amount of displacement of the sample S in the Z-axis direction at each position in the X-axis and Y-axis directions in the scanning range. The information processing device 20 causes the display device 30 to display information such as the shape of the surface of the sample S based on the measurement data.

The image 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 corresponds to the surface height at each position on the sample stage 14, and at the position where the sample S is present, it corresponds to the height including the sample S. The information processing device 20 displays the created image data on the display device 30. In addition, various information is input from the user via the input device 40.

[Hardware configuration of information processing device]
2 is a diagram showing an example of the hardware configuration of the information processing device 20. Referring to FIG. 2, the information processing device 20 has, as main components, 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, and an input I/F 172. The components are connected to each other by a data bus. At least a part of the hardware configuration of the information processing device 20 may be located inside the measuring device 10. Alternatively, the information processing device 20 may be configured as a separate entity from the scanning probe microscope 100, and configured to communicate bidirectionally with the scanning probe microscope 100.

The communication I/F 168 is an interface for communicating with the measurement device 10. 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 ROM 162 stores the programs executed by the CPU 160. The RAM 164 can temporarily store data generated by the execution of the programs in 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 working 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.

The program stored in ROM 162 may be stored in a storage medium and distributed as a program product. Alternatively, the program may be provided by an information provider as a so-called product program that can be downloaded via the Internet or the like. The information processing device 20 reads the program provided on a storage medium or via the Internet or the like. The information processing device 20 stores the read program in a specified storage area (e.g., ROM 162). By executing the program, the CPU 160 can execute the image data acquisition process described below.

The display device 30 can display a setting screen for setting the conditions for acquiring image data. In addition, while acquiring image data, the display device 30 can display image data created by the information processing device 20 and data obtained by processing this image data.

The input device 40 accepts inputs, including instructions from a user (e.g., an analyst) to the information processing device 20. The input device 40 includes a keyboard, a mouse, and a touch panel that is integrated with the display screen of the display device 30, and accepts image acquisition conditions, etc.

[Measurement range of sample S]
A user can input a measurement range of the sample S from the input device 40. FIG. 3 is a diagram showing an example of the measurement range R1. In the example of FIG. 3, the measurement range R1 is set to a rectangular shape. As shown in FIG. 3, the information processing device 20 relatively moves the probe 3 so as to reciprocate along a measurement path L (first line path) in the Y-axis direction of the sample S. In the example of FIG. 3, the positive direction of the Y-axis corresponds to the "first direction" of the present disclosure, and the negative direction of the Y-axis corresponds to the "second direction" of the present disclosure. When the reciprocating movement of the probe 3 ends in the measurement path L, the probe 3 is relatively moved a predetermined amount in the X-axis direction. Then, the probe 3 relatively moves so as to reciprocate again in the next measurement path (second line path). In this way, the probe 3 reciprocates in all lines in the measurement range R1. In addition, as a modified example, the probe 3 may be reciprocated in the X-axis direction.

[Processing of information processing device]
FIG. 4 is a functional block diagram of the information processing device 20. The information processing device 20 has an input unit 102, a processing unit 104, a driving unit 106, and a storage unit 108. The input unit 102 receives measurement data (applied voltage Vz and deviation Sd) from the Z-direction driving unit 18. This measurement data is output to the processing unit 104. The processing unit 104 creates measurement data by calculating the amount of displacement of the sample S in the Z-axis direction. Here, data created by the processing unit 104 when the probe 3 is relatively moved in the first direction described above is referred to as "first measurement data". The first measurement data is measurement data in the forward path. Moreover, data created by the processing unit 104 when the probe 3 is relatively moved in the second direction described above is referred to as "second measurement data". The second measurement data is measurement data in the return path. In this way, the processing unit 104 creates the first measurement data and the second measurement data.

The processing unit 104 also determines whether the deviation Sd is zero. When the measurement of the sample S is in a normal state, the deviation Sd becomes zero as a result of the above-mentioned feedback control being executed. However, the deviation Sd may not become zero due to the following reasons. The reasons include a first cause and a second cause.

The first cause is the presence of excessively uneven portions in the sample S, as described below. Excessively uneven portions refer to excessively high convex portions and excessively deep concave portions. Excessively high convex portions are convex portions having a height greater than the above-mentioned first movement range in the Z-axis direction (the movement range of the sample stage 14 by the fine movement mechanism 12). Moreover, excessively deep concave portions are concave portions having a depth greater than the above-mentioned first movement range in the Z-axis direction. Here, the first movement range of the sample stage 14 by the fine movement mechanism 12 is several μm to several tens of μm.

The second cause is the occurrence of thermal drift. Thermal drift occurs due to heat generation from the SPM100 device or the sample S during measurement of the sample S by the SPM100. Thermal drift of the entire SPM100 device may cause an unintended change in the relative position between the probe 3 and the sample S.

There are two types of unintended changes in the relative position between the probe 3 and the sample S: the probe 3 approaches the sample S over time, and the probe 3 moves away from the sample S over time. For example, if thermal drift occurs in the direction in which the probe 3 approaches the sample S, the deviation Sd may not become zero even if the Z scanner 12z is fully contracted when the measurement of the sample S is continued. Conversely, if thermal drift occurs in the direction in which the probe 3 moves away from the sample S, the deviation Sd may not become zero even if the Z scanner 12z is fully extended. In other words, the voltage applied to the Z scanner 12z by the Z direction drive unit 18 due to the occurrence of thermal drift is at the maximum value Vmax or the minimum value Vmin, so that the deviation Sd does not become zero (the atomic force does not become constant) even if the feedback control described above is executed. Such a state is referred to as a state in which the influence of thermal drift beyond the operating range of the fine movement mechanism 12 occurs.

In the following, "thermal drift that acts to bring the probe 3 and the sample S closer together over time" is also referred to as "first thermal drift". Also, "thermal drift that acts to move the probe 3 and the sample S away from each other over time" is also referred to as "second thermal drift". Also, when thermal drift occurs, the type of the thermal drift does not change midway. For example, when a first thermal drift occurs, there is no case where a second thermal drift occurs midway. Also, when a second thermal drift occurs, there is no case where a first thermal drift occurs midway.

Next, a method for identifying the type of cause (whether it is the first cause or the second cause) will be described. When the processing unit 104 determines that the deviation Sd is not zero, it acquires the measurement data (previously acquired measurement data) stored in the memory unit 108. For example, the processing unit 104 acquires the most recently stored (most recently acquired) N pieces of measurement data, where N is an integer equal to or greater than 1. Each of the N pieces of measurement data includes the first measurement data and the second measurement data. Then, the processing unit 104 identifies the type of cause based on the measurement data.

Figure 5 is an example of past measurement data. In Figures 5(A) to 5(C), the horizontal axis indicates time t, and the vertical axis indicates the height of the sample S measured by the SPM 10. Figure 5 also shows measurement data for the outbound journey and measurement data for the return journey. The start time of the measurement on the outbound journey is "t0", the reversal time from the outbound journey to the return journey is "t1", and the end time of the measurement on the return journey is "t2". Note that in the example of Figure 5, for convenience, when reversing from the outbound journey to the return journey, the end time of the measurement on the outbound journey is the same as the start time of the measurement on the return journey, but the end time of the measurement may differ from the start time of the measurement on the return journey.

The processing unit 104 converts the measurement data on the return journey into inverse data (third measurement data) in which the time series of the measurement data on the return journey is reversed. The processing unit 104 then calculates the degree of agreement between the measurement data on the forward journey (first measurement data) corresponding to the return journey and the inverse data. The degree of agreement is a value indicating the degree of agreement between the measurement data on the forward journey and the inverse data. The degree of agreement is calculated, for example, based on the average value or standard deviation of the differences between the values indicated by the measurement data on the forward journey and the inverse data, which are measured at multiple identical positions on the sample S.

Figure 5 (A) is a diagram for explaining the cause of the absence of thermal drift and the presence of excessively large unevenness (i.e., the first cause). As shown in Figure 5 (A), the measurement data during the measurement period on the forward path matches the reverse data (the degree of match is equal to or greater than a threshold). Therefore, when the deviation Sd is not zero and the processing unit 104 acquires the past measurement data shown in Figure 5 (A), it identifies the first cause.

Figure 5 (B) shows a case where a thermal drift (first thermal drift) occurs that causes the probe 3 and the sample S to approach each other. In Figure 5 (B), the measurement data on the return path shows that the probe 3 and the sample S are approaching each other due to the influence of the first thermal drift.

Figure 5(C) shows a case where a thermal drift (second thermal drift) occurs that acts to move the probe 3 and the sample S away from each other. In Figure 5(C), the measurement data on the return path shows that the probe 3 and the sample S move away from each other due to the influence of the second thermal drift. Note that the waveforms when no thermal drift occurs (normal waveforms) on the return paths in Figures 5(B) and 5(C) are shown by dashed lines.

Note that the measurement data in FIG. 5 is an example. For example, depending on the configuration of the SPM 100, the measurement data in FIG. 5(C) may be acquired when a first thermal drift occurs, and the measurement data in FIG. 5(B) may be acquired when a second thermal drift occurs.

As shown in Figures 5(B) and 5(C), the measurement data during the measurement period on the forward path does not match the reverse data (the degree of match is less than a threshold). Therefore, when the deviation Sd is not zero and the processing unit 104 acquires the past measurement data shown in Figure 5(B), it identifies the second cause (the occurrence of a first thermal drift). Also, when the deviation Sd is not zero and the processing unit 104 acquires the past measurement data shown in Figure 5(C), it identifies the second cause (the occurrence of a second thermal drift).

When the processing unit 104 identifies the type of cause, it stores a flag (cause information) capable of identifying the type of cause in the storage unit 108. When the processing unit 104 identifies the first cause, it stores an unevenness flag in the storage unit 108. This unevenness flag is a flag indicating that an excessively uneven portion has been detected. When the processing unit 104 identifies the second cause, it stores a thermal drift flag in the storage unit 108. The thermal drift flag is a flag indicating that a thermal drift has been detected. Furthermore, when the processing unit 104 identifies the first or second cause, it transmits a cause signal indicating the identified cause to the measuring device 10. By receiving this cause signal, the measuring device 10 can identify the cause that has occurred.

Furthermore, if the sample S has an excessively uneven portion, which is the first cause, not only will the SPM 100 be unable to measure the sample S properly, but continuing the measurement may cause the sample S and the probe 3 to come into contact with each other, damaging at least one of the sample S and the probe 3. Therefore, the SPM 100 of this embodiment executes a second control to eliminate the influence of the first cause, and continues the measurement after the second control.

FIG. 6 is a diagram showing the second control for eliminating the influence of the first cause. In FIG. 6, the sample S and the measurement range R1 set by the user are shown. Then, as shown in FIG. 6(A), it is assumed that the deviation Sd does not become zero (a special convex portion exists) in the portion α. In this case, the driving unit 106 executes a retraction process (a process for increasing the distance between the probe 3 and the sample stage 14 (sample S)) by driving the coarse movement mechanism 13. This allows the SPM 100 to prevent the probe 3 from colliding with the sample S. Then, the measuring device 10 sets the voltage applied from the Z direction driving unit 18 to the Z scanner 12z to 0. This is because there is a high possibility that the Z scanner 12z is fully contracted or fully extended in order to follow the shape of the excessively uneven portion. Furthermore, the processing unit 104 changes the measurement range from the measurement range R1 to a new measurement range R2 as shown in FIG. 6(B). The driving unit 106 drives the coarse movement mechanism 13 to move the new measurement range R2 so that it can be measured. Then, the measurement device 10 resumes measurement of the sample S in the measurement range R2. Because the voltage applied to the Z scanner from the Z direction driving unit 18 is set to 0, the sample stage 14 is driven to the initial position. Therefore, the SPM 100 can reduce collision between the probe 3 and the sample stage 14, and can measure the measurement range R2 with a margin in the extension and contraction range of the Z scanner 12z.

Here, the measurement range R2 is the range excluding the portion α, that is, the measurement range excluding the portion α where the atomic force was not constant, and is desirably the same area as the measurement range R1. More specifically, the measurement range R2 is the range adjacent to the portion α. "Adjacent to the portion α" may mean "the portion α exists on the frame that forms the measurement range R2". Also, "adjacent to the portion α" may mean "a predetermined distance away from the frame that forms the measurement range R2". Also, the information processing device 20 stores the XY coordinates of the portion α where the first cause occurred. Then, the information processing device 20 sets a new measurement range R2 based on the XY coordinates of the portion α.

Furthermore, if the first cause occurs again in the new measurement range R2, a new measurement range is set excluding the portion α where the first cause occurred again. In this way, SPM 100 repeats resetting the measurement range until the measurement in that measurement range is completed without the first cause occurring. Furthermore, if a measurement range in which the first cause does not occur cannot be set for sample S despite resetting the measurement range multiple times, SPM 100 determines that measurement of sample S is impossible and ends the measurement process. Therefore, information processing device 20 executes a notification indicating that measurement is impossible.

Furthermore, if thermal drift, which is the second cause, occurs, the SPM 100 cannot properly measure the sample S. Therefore, the SPM 100 of this embodiment executes a second control to reduce the influence of the second cause, and continues the measurement after the second control.

During the measurement of the sample S, it is assumed that the deviation Sd does not become zero (the influence of thermal drift exceeding the operating range of the fine movement mechanism 12 occurs). In this case, the driving unit 106 needs to execute a retraction process (a process of increasing the distance between the probe 3 and the sample stage 14 (sample S)) by driving the coarse movement mechanism 13. The second control for eliminating the first cause and the second cause includes this retraction process. This makes it possible to prevent the probe 3 from colliding with the sample S. Then, the measuring device 10 sets the applied voltage to the Z scanner 12z to 0. As described above, in the "state in which the influence of thermal drift exceeding the operating range of the fine movement mechanism 12 occurs", the voltage applied to the Z scanner 12z by the Z direction driving unit 18 is in the maximum value Vmax or the minimum value Vmin, so the voltage is adjusted to 0. The second control for eliminating the first cause and the second cause includes a process of setting the applied voltage to 0. Furthermore, the driving unit 106 drives the coarse movement mechanism 13 to bring the probe 3 and the sample S closer together again, and resumes the measurement of the sample S in the measurement range R1. Since the voltage applied to the Z scanner from the Z direction driving unit 18 is set to 0, the Z scanner 12z can expand and contract again.

[How SPM works]
Fig. 7 is a flow chart for explaining the operation method of the SPM 100. The process in Fig. 7 is executed for each measurement point in the set measurement range.

In step S2, the SPM 100 acquires the deviation Sd. Next, in step S4, the SPM 100 drives the Z scanner 12z so that Sd = 0 by executing feedback control. Next, in step S5, the SPM 100 judges whether or not Sd = 0. If Sd = 0, the SPM 100 stores the measurement data at the time when it was judged that Sd = 0 in the memory unit 108 in step S21. Next, in step S22, the SPM 100 judges whether or not the measurement of the sample S has been completed. If it is judged YES in S22, the process ends. On the other hand, if it is judged NO in step S22, the process returns to step S2.

If the answer is NO in step S5, then in step S6, the SPM 100 temporarily stops the measurement. Next, in step S7, the SPM 100 drives the coarse movement mechanism 13 to move the sample stage 14 away from the cantilever 2. Then, in S8, the SPM 100 sets the voltage applied from the Z direction drive unit 18 to the Z scanner 12 to 0. Furthermore, in step S9, the SPM 100 identifies the reason why Sd=0 was not achieved.

Figure 8 is a diagram for explaining the cause identification process of step S9. In step S72, SPM 100 judges whether measurement data is stored in memory 108. Here, the measurement data is the measurement data for sample S for which the process of Figure 7 has been started. If there is no measurement data (for example, if the measurement of the first line has not been completed), SPM 100 cannot identify the cause. Therefore, if the measurement data is not stored in memory 108 in step S72 (NO in step S72), SPM 100 stops the measurement in step S82 and then ends the process. SPM 100 may also notify the user that the process has ended.

On the other hand, if the answer is YES in step S72, the process proceeds to step S74. In step S74, SPM100 generates the reverse data described above. Next, in step S76, it is determined whether the degree of match between the forward data and the generated reverse data is equal to or greater than a threshold value (see the explanation of FIG. 5).

If the answer is YES in step S76 (i.e., the case is as shown in FIG. 5(A)), then in step S78, SPM 100 detects an excessively uneven portion (identifies the first cause). On the other hand, if the answer is NO in step S76 (i.e., the case is as shown in FIG. 5(B) or FIG. 5(C)), then in step S80, SPM 100 detects thermal drift (identifies the second cause).

Returning to FIG. 7 for explanation, when the processing of step S9 is completed, the SPM 100 determines the identified cause in step S10. If the cause is excessive unevenness, the processing proceeds to step S11, and if the cause is thermal drift, the processing proceeds to step S16.

In step S11, SPM 100 stores the uneven portion flag in a predetermined storage area (for example, RAM 164 shown in FIG. 2). Next, in step S12, SPM 100 sets a new measurement range R2 (see FIG. 6) that excludes the excessively uneven portion (i.e., the portion determined in step S5 that the deviation Sd is not 0). Next, in step S14, SPM 100 resumes measurement of sample S in the new measurement range R2, and the process returns to step S2.

In addition, in step S16, the SPM 100 stores the thermal drift flag. Next, in step S20, the SPM 100 again drives the coarse adjustment mechanism 13 to bring the probe 3 and the sample stage 14 (sample S) closer together, resumes measurement of the sample S in the measurement range R1, and the process returns to step S2.

During sample measurement with a conventional SPM, there are cases where the atomic force does not remain constant even if the above-mentioned feedback control is performed. This is the case, for example, when the sample has a convex portion that is too large for the SPM to measure. If the measurement is continued with the convex portion present on the sample, there is a possibility that an inaccurate measurement result will be obtained.

Therefore, if Sd=0 is not satisfied (if the result of step S5 is NO), SPM100 stops the measurement in step S6. Therefore, SPM100 can reduce the occurrence of inaccurate measurement results.

In addition, if the SPM stops measuring the sample, there may be a problem of a delay in the end time of the sample measurement.

In addition, for example, there are cases where the SPM 100 executes a measurement that requires a long time. Measurements that require a long time include, for example, measurements with a high pixel count, measurements at a slow scanning speed, measurements of multiple samples, and the like. In the case of measurements that require a long time like this, the user may be located at a distance from the SPM 100. In this case, if the sample measurement stops unintentionally by the user, there is a risk that a long time will pass without the user noticing that the measurement has stopped. Furthermore, it will be necessary to start the measurement again, which places a burden on the user.

On the other hand, if the atomic force is not constant, the SPM 100 stops the measurement of the sample S, executes the second control, and resumes the measurement of the sample after executing the second control (see steps S14 and S20 in FIG. 7). The second control is a control for reducing the influence of the cause that has occurred. In the present embodiment, the second control is, for example, steps S7 and S8. The SPM 100 resumes the measurement of the sample after executing the second control (steps S14 and S20). Therefore, the SPM 100 can resume the measurement of the sample S after eliminating the cause that does not result in Sd=0. This allows the user to reduce the occurrence of delays in the measurement of the sample. The user does not need to perform an operation to have the SPM 100 measure the sample S again, which reduces the burden on the user.

The second control also includes a process of retracting the sample stage 14 (step S7). This reduces the risk of the probe 3 colliding with the sample stage 14.

The second control also includes a process of setting the voltage applied to the Z scanner 12z to 0. Therefore, the sample stage 14 is driven to the initial position. Therefore, the SPM 100 can reduce the collision between the probe 3 and the sample stage 14, and can measure the measurement range R2 with a margin in the extension and contraction range of the Z scanner 12z.

Furthermore, the SPM 100 identifies the cause based on the past first measurement data and second measurement data (see FIG. 8 ). Therefore, the SPM 100 can identify the cause why the atomic force is not constant.

Furthermore, if the degree of agreement between the forward data and reverse data described above is higher than a threshold value, SPM100 stores a concave/convex portion flag and executes the control of step S12 as the second control. The control of step S12 is a control for setting the measurement range of the sample S to a measurement range excluding the portion where the atomic force was not constant. Therefore, SPM100 can measure the sample S in the portion other than the special convex portion by setting the measurement range R1 of the sample S to the measurement range R2 excluding the portion α.

As shown in FIG. 6, the newly set measurement range R2 is adjacent to the portion α where the special convex portion exists (the portion where the deviation Sd does not become zero even when feedback control is executed). Therefore, the amount of movement on the XY plane when changing the measurement range can be minimized.

If the first measurement data and the second measurement data have not been acquired (NO in step S72 in FIG. 8), the SPM 100 stops measuring the sample (step S82). This makes it possible to prevent the measurement of the sample S from being continued in a state in which the cause of Sd not being zero cannot be identified.

[Other embodiments]
(1) The information processing device 20 may execute a notification based on the identified cause (the type of the stored flag). For example, when the first cause is identified (when the measurement range R1 is set to the measurement range R2), the display device 30 may notify the user. FIG. 9 shows an example of a notification message displayed in the display area 30A of the display device 30. In the example of FIG. 9, a notification message 140 is displayed saying "The measurement range has been changed because an unmeasurable convex or concave portion was found." This notification is executed at a predetermined timing after the occurrence of the first cause. This predetermined timing is, for example, the timing when the measurement of the sample S in the measurement range R2 is completed. This allows the SPM 100 to make the user aware that an unmeasurable convex or concave portion was found in the measurement range and that the measurement range has been changed.

Furthermore, the information processing device 20 may notify the user via the display device 30 when the second cause occurs. FIG. 10 shows an example of a notification message displayed in the display area 30A of the display device 30. The notification message 150 in FIG. 10 reads, "Thermal drift has occurred." By providing such a notification, the SPM 100 can make the user aware that thermal drift has occurred.

(2) In FIG. 6, a configuration has been described in which the SPM 100 automatically changes the measurement range when a special convex portion or special concave portion of the sample S is detected. However, there are cases in which the user does not wish to change the measurement range in this manner. In consideration of this, the SPM 100 may be configured to allow the user to select between an automatic measurement mode and a stop mode. The automatic measurement mode is a mode in which measurement of the sample S is resumed after measurement of the sample S is stopped. The stop mode is a mode in which measurement of the sample S is not resumed after measurement of the sample S is stopped. The automatic measurement mode corresponds to the "first mode" of the present disclosure, and the stop mode corresponds to the "second mode" of the present disclosure.

Figure 11 is an example of a mode selection screen. This selection screen is displayed in the display area 30A of the display device 30. This selection screen includes a sentence 190 saying "Please select a mode," an option 192 for an automatic measurement mode, and an option 194 for a stop mode.

The user can set the mode by checking the check box of the desired option. For example, the user uses the input device 40 to check the check box. The SPM 100 accepts the mode selection input from the user and sets the selected mode. In this way, the user can select either the stop mode or the automatic measurement mode, which improves user convenience.

7, when thermal drift occurs, the voltage applied to the Z scanner 12z is reset to 0 in step S8, and then the measurement is immediately resumed in step S20. However, if the measurement is immediately resumed, the influence of the thermal drift of the entire SPM 100 may remain, and an unintended change in the relative position between the probe 3 and the sample S may occur again due to the influence of the thermal drift exceeding the operating range of the fine movement mechanism 12.

Therefore, a waiting time may be provided for the thermal drift of the entire SPM 100 to be reduced or eliminated before the measurement of the sample S is resumed. In this way, the second control in the event that thermal drift occurs includes a process of stopping the measurement of the sample S for the waiting time.

In this modified example, a method for calculating this waiting time will be described. Generally, when thermal drift occurs, the amount of thermal drift (degree of influence of thermal drift) decreases with the passage of time from the time of occurrence (see graph A in FIG. 12). The SPM 100 of this modified example calculates (or estimates) the waiting time based on this phenomenon.

Figure 12 is a diagram for explaining a method for predicting waiting time. As shown in Figure 12, the amount of thermal drift M1 at timing t11, the amount of thermal drift M2 at timing t12, plot A1, and plot A2 are shown. In addition, graph A of a function showing the relationship between waiting time and thermal drift is shown.

The information processing device 20 creates function graph A based on the thermal drift amount M1, the thermal drift amount M2, and the elapsed time T0. More specifically, the information processing device 20 calculates the difference ΔM between the thermal drift amount M1 and the thermal drift amount M2. The information processing device 20 then calculates the rate of change of the thermal drift amount by dividing the difference ΔM by the elapsed time T0. Then, the information processing device 20 creates function graph A based on the rate of change. The formula for creating the function is stored in the memory unit 108, for example.

Then, the information processing device 20 calculates the time T1 until the amount of thermal drift reaches the minimum value M0 (timing t13) based on graph A as the waiting time. Note that the start timing of the waiting time T1 is, for example, the timing when the calculation of the waiting time T1 is completed.

Figure 13 is a diagram for explaining the thermal drift amount M1 and the thermal drift amount M2. The information processing device 20 uses past measurement data of two or more measurement paths (two or more lines). As shown in Figure 13 (A), the information processing device 20 calculates a first measurement difference value M1a based on the first measurement data (measurement data of the forward path) and the second measurement data (measurement data of the return path) in the first measurement path of the sample S (the first line in the example of Figure 13). Specifically, the information processing device 20 calculates the reverse data of the forward path (data whose time series is reversed). In Figure 13 (A), the reverse data of the forward path is shown by a dashed line. Then, the information processing device 20 calculates the first measurement difference value M1a, which is the difference value between the reverse data and the return path data. The first measurement difference value M1a is a value according to the thermal drift amount. The larger the thermal drift amount, the larger the measurement difference value. In addition, the information processing device 20 calculates the amount of thermal drift M1 by multiplying the first measurement difference value M1a by a predetermined coefficient C. The coefficient C is a real number and may be set to 1.

Also, as shown in FIG. 13B, the information processing device 20 calculates a second measurement difference value M2a based on the first measurement data (measurement data of the forward path) and the second measurement data (measurement data of the return path) in the second measurement path of the sample S (the second line in the example of FIG. 13). Specifically, the information processing device 20 calculates the reverse data of the forward path (data whose time series is reversed). In FIG. 13B, the reverse data of the forward path is shown by a broken line. Then, the information processing device 20 calculates a second measurement difference value M2a, which is a difference value between the reverse data and the return path data. The second measurement difference value M2a is a value according to the amount of thermal drift. Also, as described above, in general, when thermal drift occurs, the amount of thermal drift decreases with the passage of time from the time of the occurrence. Therefore, the second measurement difference value M2a is smaller than the first measurement difference value M1a. Also, the information processing device 20 calculates the amount of thermal drift M2 by multiplying the second measurement difference value M2a by the above-mentioned coefficient C.

Furthermore, the information processing device 20 acquires the elapsed time T0 from when the relative reciprocating movement of the probe 3 in the first measurement path ends (timing t11 in FIG. 12) to when the relative reciprocating movement of the probe in the second measurement path ends (timing t12 in FIG. 12). The information processing device 20 can acquire the elapsed time T0 from the scanning speed of the probe 3 and the number of pixels to be measured. The information processing device 20 may also have a timer for measuring the elapsed time T0.

Then, the information processing device 20 creates graph A based on the thermal drift amount M1 (a value calculated from the first measurement difference value M1a), the thermal drift amount M2 (a value calculated from the second measurement difference value M2a), and the elapsed time T0, and uses the graph A to calculate the waiting time T1.

Figure 14 is a flowchart for explaining the operation method of the SPM of this modified example. In the flowchart of Figure 14, steps S17 and S18 are added between steps S16 and S20 of the flowchart of Figure 7.

When the process of step S16 is completed, in step S17, SPM100 calculates the waiting time T1. Next, in step S18, SPM100 determines whether the waiting time T1 has elapsed. SPM100 executes the process of stopping the measurement of the sample S for the waiting time as the second control described above (NO in step S18). Then, when the waiting time T1 has elapsed (YES in step S18), SPM100 resumes the measurement of the sample S in step S20.

15 is a flowchart of the waiting time calculation process in step S17. In step S102, the SPM 100 calculates a first measurement difference value M1a based on the first and second measurement data in the past first measurement path. Next, in step S104, the SPM 100 calculates a second measurement difference value M2a based on the first and second measurement data in the past second measurement path .

Next, in step S106, SPM 100 acquires elapsed time T0. Then, SPM 100 calculates waiting time T1 by creating graph A. Note that in this modified example, waiting time T1 is calculated using data from two plots (plot A1 and plot A2) as shown in FIG. 12, but graph A may be calculated using data from three or more plots.

According to this modified example, the SPM 100 can calculate the waiting time T1 according to the amount of thermal drift that is occurring. Furthermore, the SPM 100 resumes the measurement of the sample S after the waiting time T1 has elapsed, so that the measurement of the sample S can be performed with reduced effects of thermal drift.

In this modified example, the SPM 100 calculates the waiting time T1, but the waiting time T1 may be a predetermined time. The predetermined time is, for example, one hour. The waiting time T1 may also be set by the user. Even with this configuration, the SPM 100 resumes measurement of the sample S after the waiting time T1 has elapsed, so that a measurement of the sample S with reduced effects of thermal drift can be performed.

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

(1) A scanning probe microscope according to one embodiment measures a sample and includes a sample stage on which the sample is placed, a probe positioned opposite the sample, a first drive mechanism that moves the probe relatively along the surface of the sample by executing a first control so that a physical quantity acting between the probe and the sample becomes constant, and a control device that stops the measurement of the sample if the physical quantity does not become constant despite the execution of the first control.

With this configuration, even if the physical quantity acting between the probe and the sample is not constant, the measurement of the sample is stopped, thereby reducing the possibility of obtaining inaccurate measurement results.

(2) In the scanning probe microscope described in 1, when the physical quantity does not become constant, the control device stops the measurement of the sample, executes the second control, and resumes the measurement of the sample after executing the second control.

With this configuration, it is possible to resume measurement of the sample even if the physical quantity acting between the probe and the sample is not constant.

(Clause 3) The scanning probe microscope described in paragraph 2 further includes a second drive mechanism that executes a retraction process to increase the distance between the probe and the sample stage, and the second control includes the retraction process.

With this configuration, when the physical quantity acting between the probe and the sample is not constant, a retraction process is performed to increase the distance between the probe and the sample stage, thereby reducing collisions between the probe and the sample stage.

(Clause 4) In the scanning probe microscope described in clause 2 or 3, the first driving mechanism drives the sample stage in response to an applied voltage, and when the applied voltage is zero, drives the sample stage to an initial position, and the second control includes a process of setting the voltage applied to the first driving mechanism to zero.

With this configuration, when the physical quantity acting between the probe and the sample is not constant, the sample stage can be driven to the initial position, reducing the chance of the probe colliding with the sample stage when sample measurement is resumed.

(5) In the scanning probe microscope described in any one of paragraphs 2 to 4, the control device relatively moves the probe back and forth in a first direction perpendicular to the height direction of the sample and in a second direction opposite to the first direction along the same measurement path of the sample to obtain measurement data of the sample, stores the first measurement data obtained by moving the probe in the first direction and the second measurement data obtained by moving the probe in the second direction along the same measurement path, and, if the physical quantity is not constant, identifies the cause why the physical quantity is not constant based on the stored first measurement data and second measurement data, and stores cause information that can identify the identified cause.

With this configuration, cause information can be identified based on the first measurement data and the second measurement data.

(6) In the scanning probe microscope described in 5, when the degree of agreement between the first measurement data and the data obtained by reversing the time series of the second measurement data is equal to or greater than a threshold, the control device executes, as the second control, a control for setting the measurement range of the sample to a measurement range excluding the portion where the physical quantity is not constant.

With this configuration, if the degree of coincidence is equal to or greater than the threshold, there is a high possibility that the sample contains a convex or concave portion that cannot be measured by the scanning probe microscope. Since it is impossible to perform measurement in a measurement range that includes the location where such a convex or concave portion exists, the sample can be properly measured by setting a measurement range that excludes the location where the convex or concave portion exists.

(7) In the scanning probe microscope described in 6, the measurement range that is set is a range adjacent to the location.

This configuration allows the amount of drive of the first drive mechanism to be minimized when changing the range.

(Item 8) In the scanning probe microscope described in any one of Items 5 to 7, the control device executes, as the second control, a process of stopping the measurement of the sample for a predetermined waiting time when the degree of agreement between the first measurement data and the data obtained by reversing the time series of the second measurement data is less than a threshold value.

With this configuration, the scanning probe microscope resumes measuring the sample after the standby time has elapsed, allowing measurements to be performed on the sample S with reduced effects of thermal drift.

(Item 9) In the scanning probe microscope described in any one of Items 5 to 7, when the degree of agreement between the first measurement data and the data obtained by reversing the time series of the second measurement data is less than a threshold value, the control device calculates a first measurement difference value based on the first measurement data and the second measurement data in the first measurement path of the sample, calculates a second measurement difference value based on the first measurement data and the second measurement data in the second measurement path of the sample, obtains the elapsed time from when the relative reciprocating movement of the probe ends in the first measurement path to when the relative reciprocating movement of the probe ends in the second measurement path, calculates a waiting time based on the first measurement difference value, the second measurement difference value, and the elapsed time, and executes a process of stopping the measurement of the sample for the calculated waiting time as the second control.

With this configuration, it is possible to calculate a waiting time according to the amount of thermal drift that is occurring. Furthermore, since the scanning probe microscope resumes measuring the sample after the waiting time has elapsed, it is possible to perform measurements on the sample S with reduced effects of thermal drift.

(10) In the scanning probe microscope described in any one of paragraphs 5 to 9, the control device stops measuring the sample if the first measurement data and the second measurement data are not stored.

With this configuration, if the first and second measurement data are not stored, for example if one reciprocating movement is not completed, the cause cannot be identified. In this case, the measurement of the sample can be stopped, ensuring safety.

(Item 11) In the scanning probe microscope according to any one of items 5 to 10, the control device executes a notification based on the cause information.

According to this configuration, it is possible to make the user aware of the occurrence of the cause.
(Item 12) In the scanning probe microscope described in any one of Items 2 to 11, the control device is capable of switching between a first mode in which the sample measurement is stopped and then restarted, and a second mode in which the sample measurement is not restarted and then stopped, by user input.

With this configuration, the user can select either a first mode in which the sample measurement is stopped and then restarted, or a second mode in which the sample measurement is stopped and then not restarted.

(Clause 13) A control method according to another aspect is a control method for a scanning probe microscope that measures a sample and that includes a sample stage on which a sample is placed, a probe placed facing the sample, and a first drive mechanism that moves the probe relatively along the surface of the sample, the control method including executing a first control that keeps a physical quantity acting between the probe and the sample constant, and stopping the measurement of the sample if the physical quantity does not become constant despite the execution of the first control.

With this configuration, even if the physical quantity acting between the probe and the sample is not constant, the measurement of the sample is stopped, thereby reducing the possibility of obtaining inaccurate measurement results.

It is intended from the outset that the configurations described in the above-mentioned embodiments and modified examples may be combined as appropriate, including combinations not mentioned in the specification, to the extent that no inconvenience or contradiction arises.

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

1 Optical system, 2 Cantilever, 3 Probe, 4 Holder, 5 Beam splitter, 6 Laser light source, 7 Reflector, 8 Photodetector, 10 Measuring device, 12 Fine movement mechanism, 13 Coarse movement mechanism, 14 Sample stage, 20 Information processing device, 22 Feedback signal generating unit, 30 Display device, 30A Display area, 40 Input device, 100 Scanning probe microscope, 102 Input unit, 104 Processing unit, 106 Driving unit, 162 ROM, 164 RAM.

Claims (15)

1. A scanning probe microscope for measuring a sample, comprising:
a sample stage on which the sample is placed;
A probe disposed facing the sample;
a first drive mechanism that relatively moves the probe along the surface of the sample by executing a first control so that a physical quantity acting between the probe and the sample is constant;
a control device that stops the measurement of the sample when the physical quantity does not become constant despite the execution of the first control,
The control device includes:
a first direction perpendicular to a height direction of the sample and a second direction opposite to the first direction are perpendicular to the height direction of the sample, and the probe is moved back and forth relative to the first direction along the same measurement path of the sample to acquire measurement data of the sample;
when the physical quantity is not constant, if a degree of agreement between first measurement data acquired by moving the probe in the first direction and time-series reversed data of second measurement data acquired by moving the probe in the second direction is greater than a threshold, cause information indicating a cause that the sample has an excessively large concave portion or an excessively large convex portion is stored;
When the physical quantity does not become constant and the degree of coincidence is smaller than the threshold value, cause information indicating that a cause is that thermal drift of the scanning probe microscope is occurring is stored . 1. A scanning probe microscope for measuring a sample, comprising:
a sample stage on which the sample is placed;
A probe disposed facing the sample;
a first drive mechanism that relatively moves the probe along the surface of the sample by executing a first control so that a physical quantity acting between the probe and the sample is constant;
a control device that stops the measurement of the sample when the physical quantity does not become constant despite the execution of the first control,
The control device includes:
a first direction perpendicular to a height direction of the sample and a second direction opposite to the first direction are perpendicular to the height direction of the sample, and the probe is moved back and forth relative to the first direction along the same measurement path of the sample to obtain measurement data of the sample;
executing a second control for setting a measurement range of the sample to a measurement range excluding a portion where the physical quantity did not become constant when a degree of agreement between first measurement data acquired by moving the probe in the first direction and time-series reversed data of second measurement data acquired by moving the probe in the second direction is greater than a threshold value when the physical quantity does not become constant;
After executing the second control, the scanning probe microscope resumes measurement of the sample. 1. A scanning probe microscope for measuring a sample, comprising:
a sample stage on which the sample is placed;
A probe disposed facing the sample;
a first drive mechanism that relatively moves the probe along the surface of the sample by executing a first control so that a physical quantity acting between the probe and the sample is constant;
a control device that stops the measurement of the sample when the physical quantity does not become constant despite the execution of the first control,
The control device includes:
a first direction perpendicular to a height direction of the sample and a second direction opposite to the first direction are perpendicular to the height direction of the sample, and the probe is moved back and forth relative to the first direction along the same measurement path of the sample to obtain measurement data of the sample;
executing a second control for stopping measurement of the sample for a predetermined waiting time when a degree of agreement between first measurement data acquired by moving the probe in the first direction and time-reversed data of second measurement data acquired by moving the probe in the second direction is smaller than a threshold value when the physical quantity is not constant;
After executing the second control, the scanning probe microscope resumes measurement of the sample. 1. A scanning probe microscope for measuring a sample, comprising:
a sample stage on which the sample is placed;
A probe disposed facing the sample;
a first drive mechanism that relatively moves the probe along the surface of the sample by executing a first control so that a physical quantity acting between the probe and the sample is constant;
a control device that stops the measurement of the sample when the physical quantity does not become constant despite the execution of the first control,
The control device includes:
a first direction perpendicular to a height direction of the sample and a second direction opposite to the first direction are perpendicular to the height direction of the sample, and the probe is moved back and forth relative to the first direction along the same measurement path of the sample to acquire measurement data of the sample;
When the physical quantity is not constant, if a degree of agreement between first measurement data acquired by moving the probe in the first direction and time-reversed data of second measurement data acquired by moving the probe in the second direction is smaller than a threshold value,
calculating a first measurement difference value based on the first measurement data and the second measurement data in a first measurement path of the sample;
calculating a second measurement difference value based on the first measurement data and the second measurement data in a second measurement path of the sample;
acquiring an elapsed time from when the relative reciprocating movement of the probe ends in the first measurement path to when the relative reciprocating movement of the probe ends in the second measurement path;
calculating a standby time based on the first measurement difference value, the second measurement difference value, and the elapsed time;
executing a second control for stopping the measurement of the sample for the calculated waiting time;
After executing the second control, the scanning probe microscope resumes measurement of the sample . The control device includes:
if the physical quantity does not become constant, stopping the measurement of the sample and then executing a second control;
2. The scanning probe microscope according to claim 1 , wherein measurement of the sample is resumed after the second control is executed. the scanning probe microscope further includes a second drive mechanism that executes a retraction process to increase a distance between the probe and the sample stage;
The scanning probe microscope according to claim 5 , wherein the second control includes the retraction process. The first drive mechanism includes:
Driving the sample stage in response to the applied voltage;
When the applied voltage is zero, the sample stage is driven to an initial position;
7. The scanning probe microscope according to claim 5 , wherein the second control includes a process of setting a voltage applied to the first driving mechanism to zero. 3. The scanning probe microscope according to claim 2 , wherein the set measurement range is a range adjacent to the location. 9. The scanning probe microscope according to claim 1 , wherein the control device stops the measurement of the sample when the first measurement data and the second measurement data are not stored. The scanning probe microscope according to claim 1 , wherein the control device executes a notification based on the cause information. The control device includes:
a first mode in which the measurement of the sample is stopped and then resumed;
11. The scanning probe microscope according to claim 1 , wherein a first mode is switchable by a user input between a first mode in which the measurement of the sample is stopped and a second mode in which the measurement of the sample is not resumed. a sample stage on which a sample is placed;
A probe disposed facing the sample;
a first drive mechanism that relatively moves the probe along a surface of the sample, the method comprising:
The control method includes:
executing a first control such that a physical quantity acting between the probe and the sample becomes constant;
stopping the measurement of the sample when the physical quantity does not become constant despite the execution of the first control ;
Acquiring measurement data of the sample by relatively reciprocating the probe in a first direction perpendicular to a height direction of the sample and in a second direction opposite to the first direction along the same measurement path of the sample;
storing cause information indicating a cause that the sample has an excessively large concave portion or an excessively large convex portion when a degree of agreement between first measurement data acquired by moving the probe in the first direction and time-series reversed data of second measurement data acquired by moving the probe in the second direction is greater than a threshold value when the physical quantity is not constant;
and storing cause information indicating that a cause is that thermal drift is occurring in the scanning probe microscope when the physical quantity does not become constant and the degree of coincidence is smaller than the threshold value . a sample stage on which a sample is placed;
A probe disposed facing the sample;
a first drive mechanism that relatively moves the probe along a surface of the sample, the method comprising:
The control method includes:
executing a first control such that a physical quantity acting between the probe and the sample becomes constant;
stopping the measurement of the sample when the physical quantity does not become constant despite the execution of the first control;
Acquiring measurement data of the sample by relatively reciprocating the probe in a first direction perpendicular to a height direction of the sample and in a second direction opposite to the first direction along the same measurement path of the sample;
executing a second control for setting a measurement range of the sample to a measurement range excluding a portion where the physical quantity does not become constant when a degree of agreement between first measurement data acquired by moving the probe in the first direction and time-series reversed data of second measurement data acquired by moving the probe in the second direction is greater than a threshold value when the physical quantity does not become constant;
and resuming measurement of the sample after performing the second control. a sample stage on which a sample is placed;
A probe disposed facing the sample;
a first drive mechanism that relatively moves the probe along a surface of the sample, the method comprising:
The control method includes:
executing a first control such that a physical quantity acting between the probe and the sample becomes constant;
stopping the measurement of the sample when the physical quantity does not become constant despite the execution of the first control;
Acquiring measurement data of the sample by relatively reciprocating the probe in a first direction perpendicular to a height direction of the sample and in a second direction opposite to the first direction along the same measurement path of the sample;
executing a second control for stopping measurement of the sample for a predetermined waiting time when a degree of agreement between first measurement data acquired by moving the probe in the first direction and time-reversed data of second measurement data acquired by moving the probe in the second direction is smaller than a threshold value when the physical quantity is not constant;
and resuming measurement of the sample after performing the second control. a sample stage on which a sample is placed;
A probe disposed facing the sample;
a first drive mechanism that relatively moves the probe along a surface of the sample, the method comprising:
The control method includes:
executing a first control such that a physical quantity acting between the probe and the sample becomes constant;
stopping the measurement of the sample when the physical quantity does not become constant despite the execution of the first control;
Acquiring measurement data of the sample by relatively reciprocating the probe in a first direction perpendicular to a height direction of the sample and in a second direction opposite to the first direction along the same measurement path of the sample;
When the physical quantity is not constant, if a degree of agreement between first measurement data acquired by moving the probe in the first direction and time-reversed data of second measurement data acquired by moving the probe in the second direction is smaller than a threshold value,
calculating a first measurement difference value based on the first measurement data and the second measurement data in a first measurement path of the sample;
calculating a second measurement difference value based on the first measurement data and the second measurement data in a second measurement path of the sample;
acquiring an elapsed time from when the relative reciprocating movement of the probe ends in the first measurement path to when the relative reciprocating movement of the probe ends in the second measurement path;
calculating a standby time based on the first measurement difference value, the second measurement difference value, and the elapsed time;
executing a second control of stopping the measurement of the sample for the calculated waiting time;
and resuming measurement of the sample after performing the second control.

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