Scanning probe microscope and method for controlling scanning probe microscope

Abstract

This scanning probe microscope comprises: a measurement unit including a probe for measurement; and a controller for controlling the measurement unit. Upon acquisition of an instruction for starting the measurement, the controller identifies a predicted value of a total of drift amounts in the measurement when the measurement is started at the timing of acquiring the instruction. The predicted value is based on reference information that defines a temporal change in the drift amounts. The controller starts the measurement when the predicted value is smaller than a predetermined threshold value, and avoids the start of the measurement when the predicted value is equal to or larger than the threshold value.

Description

Scanning probe microscope and control method thereof

[0001] The present invention relates to scanning probe microscopes, and in particular to drift in scanning probe microscopes.

[0002] In a scanning probe microscope, a deviation in the positional relationship between the probe and the sample that occurs during measurement is known as drift.

[0003] Various techniques have been proposed to reduce the effects of drift in measurements using scanning probe microscopes. For example, Japanese Patent Laid-Open Publication No. 2007-278896 (Patent Document 1) discloses a scanning probe microscope that uses three-dimensional information about the surface shape of a sample and correction data for temperature drift. This scanning probe microscope acquires the three-dimensional information about the sample, calculates a probe scanning trajectory based on the three-dimensional information and the correction data, and moves the probe according to the probe scanning trajectory.

[0004] Furthermore, Japanese Patent Laid-Open Publication No. 2016-032290 (Patent Document 2) discloses a drift correction method for a scanning probe microscope. This method comprises four steps. In the first step, a probe is scanned along a scan line on a sample surface to perform shape measurement along the scan line, and then the probe is moved to the next scan line. This process is repeated. In the second step, after the shape measurement along a specific scan line in the first step is completed, a reference shape along the scan line is measured by scanning the probe along a predetermined reference shape measurement scan line on the sample surface. In the third step, the current reference shape measurement result obtained in the second step is compared with the previous reference shape measurement result to calculate the amount of drift that has occurred over time between the two. Then, in the fourth step, the current shape measurement result obtained in the first step is corrected based on the amount of drift calculated in the third step.

[0005] JP 2007-278896 A JP 2016-032290 A

[0006] In the conventional techniques described above, correction data is generated according to the drift that occurs. However, if the amount of drift that occurs is too large, problems may occur that cannot be avoided by using only the correction data. For example, if the amount of drift is too large and the probe gets too close to the sample, the probe and / or the sample may be damaged during scanning. If the drift is too large and the probe and sample are too far apart, the measurement results may become meaningless.

[0007] The present invention has been devised in view of the above circumstances, and its purpose is to provide a technique for more reliably avoiding the inconvenience that may arise due to drift in a scanning probe microscope.

[0008] A scanning probe microscope according to one aspect of the present disclosure comprises a measurement unit including a measurement probe and a controller that controls the measurement unit, wherein when the controller receives an instruction to start measurement, it determines a predicted value of the total amount of drift in the measurement when the measurement is started at the time the instruction is received, the predicted value being based on reference information that defines the change in the amount of drift over time, and the controller starts the measurement if the predicted value is less than a predetermined threshold, and avoids starting the measurement if the predicted value is equal to or greater than the threshold.

[0009] A method for controlling a scanning probe microscope according to one aspect of the present disclosure is a method for controlling a scanning probe microscope that is implemented by a computer and includes the steps of: acquiring an instruction to start measurement; calculating a predicted value of the total amount of drift in the measurement when the measurement is started at the timing when the instruction is acquired; and determining whether to start the measurement based on the predicted value, wherein the predicted value is based on reference information that defines the change in the amount of drift over time; and in the determining step, if the predicted value is less than a predetermined threshold, the measurement is started, and if the predicted value is equal to or greater than the threshold, the start of the measurement is avoided.

[0010] According to one aspect of the present disclosure, a technique is provided for more reliably avoiding problems that may arise due to drift in a scanning probe microscope.

[0011] 5 is a diagram showing an example of the configuration of a scanning probe microscope; FIG. 6 is a diagram showing an example of the scanning pattern of a probe 114; FIG. 7 is a diagram showing an example of time-varying drift amount in a scanning probe microscope 1; FIG. 8 is a flowchart of an example of processing that is started at the timing when initialization is completed upon power-on in a scanning probe microscope 1; FIG. 9 is a flowchart of a subroutine of step S70; and FIG. 10 is a diagram showing a modified example of the subroutine of FIG.

[0012] Hereinafter, embodiments of the present disclosure 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 description thereof will not be repeated.

[0013] [Configuration of a Scanning Probe Microscope] Fig. 1 is a diagram showing an example of the configuration of a scanning probe microscope. An example of a scanning probe microscope is an atomic force microscope. Note that the scanning probe microscope may be another type of scanning probe microscope (for example, a scanning tunneling microscope). In Fig. 1, the Z-axis direction represents the height direction of the sample, and the X-axis and Y-axis directions represent directions perpendicular to the Z-axis direction.

[0014] Referring to FIG. 1, a scanning probe microscope 1 includes a measurement unit 100 and a controller 150 .

[0015] The controller 150 includes a computer 132 , a scanning signal generating unit 133 , a storage device 134 , a display device 135 , and an input device 136 .

[0016] In one implementation example, computer 132 includes at least one processor and displays the results of calculations performed by the at least one processor on display device 135. Input device 136 inputs signals in response to user operations to computer 132. Storage device 134 non-temporarily stores programs executed by the processor.

[0017] The computer 132 controls the overall operation of the scanning probe microscope 1. As will be described later, when the computer 132 receives an instruction to measure a sample, it may calculate a predicted value of the amount of drift that will occur from the start of the measurement at the timing when the instruction is received until the end of the measurement, and may start the measurement in accordance with the instruction on the condition that the predicted value is less than a predetermined threshold. Note that the computer 132 may avoid starting the measurement in accordance with the instruction if the predicted value is equal to or greater than the threshold.

[0018] The measurement unit 100 includes a sample stage 112 on which a sample 110 is placed, a piezoelectric scanner 111 that displaces the sample stage, a cantilever 113 with a probe 114 formed at the tip, a displacement detection mechanism 120 that detects the displacement of the cantilever 113, and a feedback signal generating unit 131.

[0019] The piezo scanner 111 includes a Z scanner 111z that generates displacement in the Z direction based on a voltage value Vz, and an XY scanner 111xy that generates displacement in the X and Y directions based on voltage values ​​Vx and Vy.

[0020] Displacement detection mechanism 120 includes laser diode 115 and photodetector 119. In scanning probe microscope 1, when the tip of probe 114 is brought close to sample 110 to observe the surface, laser light emitted from laser diode 115 is reflected by the back surface of cantilever 113, and the reflected light is received by photodetector 119. As probe 114 is brought closer to the surface of sample 110, cantilever 113 bends like a leaf spring. The amount of bending (amount of displacement on the Z axis) is observed at the light-receiving position of photodetector 119.

[0021] The feedback signal generating unit 131 receives a detection signal from the photodetector 119. The feedback signal generating unit 131 calculates the amount of deflection of the cantilever 113 based on the detection signal. The feedback signal generating unit 131 controls the Z-direction position of the sample so that the atomic force between the probe 114 and the surface of the sample 110 is always constant. The feedback signal generating unit 131 calculates a voltage value Vz for displacing the piezo scanner 111 in the Z-axis direction based on the amount of deflection of the cantilever 113, and outputs the voltage value Vz to the Z scanner 111z.

[0022] The scanning signal generating unit 133 calculates voltage values ​​Vx and Vy in the X-axis and Y-axis directions so that the sample 110 moves relative to the probe 114 in the XY plane according to a predetermined scanning pattern, and outputs them to the XY scanner 111xy.

[0023] A signal reflecting the amount of feedback in the Z-axis direction (deviation signal Sd) is sent to computer 132 and stored in storage device 134. Based on the deviation signal Sd, computer 132 calculates the amount of surface displacement due to the unevenness of sample 110. By calculating the amount of displacement at each position in the X-axis and Y-axis directions, computer 132 recreates a three-dimensional image of the sample surface and displays it on the screen of display device 135. This three-dimensional image data is also stored in storage device 134. The data includes coordinates indicating the position on the X-Y plane and the sample height at those coordinates. Computer 132 can read out the three-dimensional image data stored in storage device 134 at any time and display it on display device 135. Computer 132 can perform height correction on the three-dimensional image data as needed and display it on display device 135.

[0024] [Threshold] The "threshold" used by the computer 132 to determine whether to start a sample measurement when the computer 132 receives an instruction to measure the sample will be described below.

[0025] Drift can occur in the scanning probe microscope 1. If the amount of drift that can occur during a measurement is too great, the probe may get too close to the sample, which may cause damage to the probe and / or sample during scanning. Also, if the amount of drift that can occur during a measurement is too great, the probe may get too far away from the sample, which may cause the measurement results to be meaningless.

[0026] On the other hand, in the scanning probe microscope 1, the amount of drift at which the above-mentioned situation occurs, whereby "the probe and / or sample are damaged during scanning" or "the measurement results become meaningless", is set as a "threshold value".

[0027] When computer 132 receives an instruction to measure a sample, it calculates a predicted value of the amount of drift that is expected to occur from the start to the end of the measurement if the measurement is started immediately. If the calculated predicted value is less than the threshold, computer 132 may start the measurement immediately in response to receiving the instruction. If the calculated predicted value is equal to or greater than the threshold, computer 132 may avoid starting the measurement at the time of receiving the instruction.

[0028] [Scanning Pattern] Fig. 2 is a diagram showing an example of a scanning pattern of the probe 114. In Fig. 2, the region to be measured on the sample 110 is shown as a measurement range R1. The measurement range R1 represents the range of the surface of the sample 110 with respect to the three-dimensional image to be acquired of the sample 110.

[0029] The scanning pattern of the probe 114 includes one or more lines indicated as a "first line," a "second line," a "third line," etc. In the scanning probe microscope 1, the probe 114 moves relative to the sample 110. That is, it may be only the probe 114 that moves, or only the sample 110, or both the probe 114 and the sample 110. In the following, for ease of explanation, the scanning pattern of the probe 114 will be explained assuming that the probe 114 moves.

[0030] On the "first line," the probe 114 moves in the negative direction of the Y axis (toward the bottom in FIG. 2 ) along line L11, and then moves in the positive direction of the Y axis (toward the top in FIG. 2 ) along line L12. That is, on the "first line," the probe 114 reciprocates along the Y axis direction. Then, the probe 114 moves in the positive direction of the X axis (toward the right in FIG. 2 ) along line L10.

[0031] Thereafter, the probe 114 moves back and forth along the Y-axis direction on the “second line,” moves along the X-axis direction, and then moves back and forth along the Y-axis direction on the “third line.” The probe 114 repeats such back and forth along the Y-axis direction and movement along the X-axis direction to scan the entire measurement range R1.

[0032] 2, the Y-axis direction constitutes an example of a “main scanning direction.” The X-axis direction is a direction that intersects with the main scanning direction and constitutes an example of a sub-scanning direction.

[0033] [Prediction curve of drift amount] Fig. 3 is a diagram showing an example of the change over time in the drift amount in the scanning probe microscope 1. In Fig. 3, the vertical axis represents the drift amount per unit time, and the horizontal axis represents the elapsed time from the completion of initialization when the power is turned on in the scanning probe microscope 1. In Fig. 3, line LP represents the prediction curve of the change over time in the drift amount.

[0034] In the example of Fig. 3, line LP is shown as a prediction curve. As shown by line LP, the amount of drift per unit time decreases over time. More specifically, the amounts of drift per unit time at times T1, T2, T3, and T4 are shown as values ​​D1, D2, D3, and D4, respectively. Value D2 is smaller than value D1, value D3 is smaller than value D2, and value D4 is smaller than value D3.

[0035] In one implementation, a predicted amount of drift expected to occur in a measurement from a certain time over a certain length of time is determined based on the amount of drift per unit time at that time and the length of time. For example, a predicted amount of drift expected in a measurement from time T1 to time TA is determined as the product of value D1 (the amount of drift per unit time at time T1) and time TA. When predicted values ​​are determined in this manner, in the example of FIG. 3 , the predicted amount of drift expected to occur in a measurement decreases the later the measurement is started. That is, the predicted amount is smaller for a measurement started at time T2 than for a measurement started at time T1, the predicted amount is smaller for a measurement started at time T3 than for a measurement started at time T2, and the predicted amount is smaller for a measurement started at time T4 than for a measurement started at time T3.

[0036] In this embodiment, the line LP is an example of information (hereinafter also referred to as "reference information") that defines the change in the drift amount over time. The reference information does not need to be in the form of a function, and may have other forms. An example of another form is the drift amount for multiple time periods from the completion of the initialization (drift amount Q0 for the time period from 0 to 1 minute, drift amount Q1 for the time period from 1 to 2 minutes, drift amount Q2 for the time period from 2 to 3 minutes, drift amount Q3 for the time period from 3 to 4 minutes, ...).

[0037] In one implementation example, the reference information is stored in the storage device 134. The computer 132 can calculate the predicted value of the drift amount described above by using the information in the storage device 134. Note that the reference information may be stored in a storage device installed outside the scanning probe microscope 1, as long as the storage device is accessible by the computer 132.

[0038] [Creating Reference Information (Information Prescribing Time-Varying Change in Drift Amount)] The reference information may be created in advance and stored in the storage device 134, or may be created by the computer 132. An example of a method for creating the reference information will be described below.

[0039] First, the computer 132 continuously measures the amount of deflection of the probe 114 for a given period of time. At this time, the position of the sample stage 112 in the scanning probe microscope 1 is adjusted so that the probe 114 abuts against the sample 110.

[0040] Then, the computer 132 identifies the amount of drift at each of a plurality of timings based on the results of the measurement of the amount of deflection. For example, the change in the amount of deflection (amount of displacement on the Z axis) from the completion of initialization of the scanning probe microscope 1 until one minute has passed is identified as the amount of drift one minute after the completion of initialization. Furthermore, the change in the amount of deflection from one minute after the completion of initialization until two minutes after the completion of initialization is identified as the amount of drift two minutes after the completion of initialization.

[0041] The computer 132 arranges the multiple drift amounts identified as described above on a time axis, obtains a quadratic curve obtained by quadratic curve approximation, and stores the obtained quadratic curve in the storage device 134 as reference information.

[0042] The approximation method used to create the reference information is not limited to quadratic curve approximation, but by using quadratic curve approximation, reference information that appropriately represents changes in the amount of drift that are expected to occur in a typical scanning probe microscope 1 can be created through relatively simple calculations.

[0043] [Processing Flow] The following describes the processing flow performed by the computer 132. Fig. 4 is a flowchart of an example of processing that is started when initialization is completed upon power-on in the scanning probe microscope 1. In one implementation example, the processing in Fig. 4 is realized by the processor of the computer 132 executing a given program. The content of the processing in Fig. 4 will be described below.

[0044] In step S10, computer 132 determines whether any instruction has been input. The instruction to computer 132 may be input by operating input device 136, may be input from an external device, or may be input according to a pre-set setting (for example, timer reservation). Computer 132 repeats the control of step S10 until it determines that an instruction has been input (NO in step S10), and when it determines that an instruction has been input (YES in step S10), it proceeds to step S20.

[0045] In step S20, computer 132 identifies the content of the input instruction. In step S30, computer 132 determines whether the input instruction is an instruction to create reference information. If computer 132 determines that the input instruction is an instruction to create reference information (YES in step S30), control proceeds to step S40. If not (NO in step S30), control proceeds to step S50.

[0046] In step S40, the computer 132 creates the reference information, and then the computer 132 returns control to step S10.

[0047] In step S50, computer 132 determines whether the input instruction is a measurement instruction. If computer 132 determines that the input instruction is a measurement instruction (YES in step S50), control proceeds to step S70, and if not (NO in step S50), control proceeds to step S60.

[0048] In step S60, the computer 132 performs the operation according to the input instructions, and then returns control to step S10.

[0049] In step S70, the computer 132 processes the measurement instruction. The contents of step S70 will be described later with reference to Figure 5. After that, the computer 132 returns control to step S10.

[0050] 5 is a flowchart of the subroutine of step S70. The contents of step S70 will be described with reference to FIG.

[0051] In step S700, the computer 132 reads out the conditions for the instructed measurement. The measurement conditions may be input to the computer 132 together with the measurement instruction, or may be registered in the computer 132 in advance.

[0052] In step S702, the computer 132 calculates, as a predicted value, the amount of drift that is predicted to occur while the measurement is being performed under the conditions read out in step S700 if the measurement is started immediately.

[0053] In calculating the predicted value, the computer 132 first identifies (estimates) the length of time required for the measurement. The length of time required for the measurement may be identified based on parameters included in the measurement conditions.

[0054] In one implementation example, the measurement conditions include the number of 3D images acquired in the measurement. If the time required to acquire one 3D image is specified, the length of time required for the measurement is specified as the product of that time and the number of 3D images acquired in the measurement. However, in the scanning probe microscope 1, the number of 3D images acquired in the measurement may be fixed at "1." In this case, the measurement conditions do not need to include the number of 3D images acquired in the measurement.

[0055] The time required to acquire one three-dimensional image may be registered as a fixed value in the scanning probe microscope 1. The time required to acquire one three-dimensional image may be registered as a fixed value for each of multiple types of sample. In this case, if the measurement conditions include the type of sample, the computer 132 can use the type to specify the time required to acquire one three-dimensional image.

[0056] In one implementation example, the measurement conditions include a scanning speed in the main scanning direction. If the scanning speed in the main scanning direction and the number of pixels in the sub-scanning direction (the "number of lines" in FIG. 2) are specified, the time required to measure one sample can be specified based on the operation speed, the number of pixels, and the scanning speed.

[0057] In one implementation, the measurement conditions include the number of pixels in the sub-scanning direction. If the scanning speed in the main scanning direction is specified, the computer 132 can use these and the scanning speed to determine the time required to acquire one 3D image.

[0058] At least one of the scanning distance and scanning speed in the main scanning direction and the number of pixels in the sub-scanning direction may be registered as a fixed value in the scanning probe microscope 1 .

[0059] Then, the computer 132 calculates the total amount of drift from the start to the end of the measurement using the length of time required for the measurement and the reference information as a predicted value.

[0060] 3 is used as reference information, the computer 132 calculates, as the predicted value, the product of the "amount of drift per unit time" at that time in the quadratic function defined by the line LP and the "time required for measurement." For example, if the computer 132 receives a measurement instruction one minute after the completion of initialization at power-on and the length of time required for measurement is two minutes, the computer 132 calculates, as the predicted value, the product of the "amount of drift per unit time" for one minute in the quadratic function and "two minutes."

[0061] In step S704, computer 132 determines whether the predicted value calculated in step S702 is less than a predetermined threshold value. If computer 132 determines that the predicted value is less than the threshold value (YES in step S704), control proceeds to step S710; otherwise (NO in step S704), control proceeds to step S706.

[0062] In step S706, the computer 132 calculates the timing at which measurement can be started. The timing at which measurement can be started is the earliest timing at which the predicted value of the amount of drift that is predicted to occur in the measurement if the measurement is started at that timing falls below the threshold value.

[0063] For example, assume that the computer 132 receives a measurement instruction two minutes after the completion of initialization, the measurement takes five minutes, and the line LP in FIG. 3 is registered as reference information. In this case, the computer 132 first calculates the product of the "amount of drift per unit time" two minutes after the completion of initialization and "5 minutes" for the function of line LP. If this product is equal to or greater than a threshold, the computer 132 performs the control of step S706. In step S706, the computer 132 calculates the product of the "amount of drift per unit time" three minutes after the completion of initialization and "5 minutes." If this product is equal to or greater than a threshold, the computer 132 further calculates the product of the "amount of drift per unit time" four minutes after the completion of initialization and "5 minutes." If this product is less than the threshold, the computer 132 identifies the timing four minutes after the completion of initialization as the "start possible timing."

[0064] In step S708, computer 132 notifies the user of the timing at which measurement can be started. The notification may be a display on display device 135, an audio output, a notification sent to a user registered in computer 132 (for example, a user who inputs a measurement instruction), or a combination of these. Thereafter, computer 132 returns control to FIG. 4.

[0065] On the other hand, in step S710, the computer 132 causes the measurement unit 100 to start the instructed measurement.

[0066] Then, in step S712, the computer 132 waits until it determines that the measurement in the measurement unit 100 has been completed (NO in step S712), and when it determines that the measurement has been completed (YES in step S712), it returns control to FIG.

[0067] According to the process described above, the creation of reference information (step S40) is performed on the condition that the computer 132 has received an instruction to create the reference information. The trigger for creating the reference information is not limited to receiving an instruction. The creation of reference information may be performed each time a measurement instruction is input, or may be performed automatically upon completion of initialization of the scanning probe microscope 1 (automatically, without the need for a specific instruction). If default reference information is registered in the scanning probe microscope 1, the creation of reference information may be omitted. However, when reference information is created in the scanning probe microscope 1, the created reference information may reflect individual differences in the scanning probe microscope 1. Furthermore, if a user uses the scanning probe microscope 1 in a special environment, the created reference information may reflect the special environment of the scanning probe microscope 1.

[0068] In the above-described process, if it is determined in step S704 that the predicted value is equal to or greater than the threshold value, an operation is performed to move the probe 114 away from the sample 110, and then, when measurement is started in step S710, an operation is performed to move the probe 114 closer to the sample 110. These operations can be performed manually by the user, for example.

[0069] According to the process described above, when the computer 132 receives a measurement instruction, it calculates a predicted value as the total amount of drift that is predicted to occur in the measurement. If the predicted value is less than a predetermined threshold, the computer 132 causes the measurement unit 100 to start measurement. On the other hand, if the predicted value is equal to or greater than the predetermined threshold, the computer 132 returns control to FIG. 4 without causing the measurement unit 100 to start measurement. In other words, the measurement is prevented from starting immediately. This prevents the measurement from starting at a time when the total amount of drift may reach the threshold during measurement.

[0070] According to the process described above, when measurement cannot be started immediately, the computer 132 calculates and notifies the user of the timing when measurement can be started. Calculation and notification of the timing when measurement can be started may be omitted. However, if the timing when measurement can be started is notified, the user can recognize the timing when the desired measurement can be started and can instruct the user to start measurement again at that timing.

[0071] The computer 132 may calculate the timing when measurement can be started, and then instruct the measurement unit 100 to start measurement when the timing when measurement can be started arrives. Such a modified example will be described with reference to Fig. 6. Fig. 6 is a diagram showing a modified example of the subroutine of Fig. 5.

[0072] In the example of FIG. 6, after the computer 132 calculates the possible start timing in step S706, the control proceeds to step S709.

[0073] In step S709, the computer 132 determines whether the time specified as the start possible timing has arrived. The computer 132 holds control at step S709 until it determines that the time specified as the start possible timing has arrived (NO in step S709). If it determines that the time has arrived (YES in step S709), the computer 132 proceeds to step S710. In step S710, the computer 132 causes the measurement unit 100 to start control.

[0074] 6 described above, if it is not possible to immediately start measurement according to the input instruction based on the relationship between the predicted value and the threshold value, computer 132 causes measurement unit 100 to start measurement when the timing at which it is possible to start arrives, without the need to input a new instruction. As a result, once an instruction is input, scanning probe microscope 1 automatically starts measurement when the timing arrives at which the total amount of drift predicted to occur in the measurement does not exceed the threshold value.

[0075] According to the process described above, the predicted value can be calculated in accordance with the measurement conditions, and as a result, in the scanning probe microscope 1, depending on the content of the instructed measurement, the measurement may or may not start immediately after being instructed.

[0076] Instead of or in addition to step S706, the computer 132 may specify the maximum number of images for which measurement can be started immediately at the time indicated.

[0077] For example, assume that the measurement conditions include "10" as the number of images to be acquired. If the predicted value calculated according to the number "10" is equal to or greater than the threshold, the computer 132 calculates a new predicted value according to the number "9." If the predicted value calculated according to the number "9" is equal to or greater than the threshold, the computer 132 further calculates a new predicted value according to the number "8." If the predicted value calculated according to the number "8" is less than the threshold, the computer 132 specifies "8" as the maximum number of images for which measurement can be started immediately.

[0078] Then, the computer 132 may notify the maximum number of sheets instead of or in addition to step S708.

[0079] When the maximum number is notified, the user again inputs a measurement instruction that includes the maximum number as the number of images to be acquired to the scanning probe microscope 1. This enables the user to immediately start measurement to acquire the maximum number of three-dimensional images possible at the time the instruction was issued to the scanning probe microscope 1.

[0080] 6, the computer 132 may specify the maximum number instead of step S706, skip step S709, and cause the measuring unit 100 to start measuring the maximum number of images in step S710. At this time, the computer 132 may notify the user that there is a difference in the number of 3D images acquired between the instructed measurement and the measurement that the computer 132 instructs the measuring unit 100 to start.

[0081] Aspects It will be understood by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0082] (Item 1) A scanning probe microscope according to one aspect comprises a measurement unit including a measurement probe, and a controller that controls the measurement unit, wherein when the controller receives an instruction to start a measurement, the controller determines a predicted value of a total amount of drift in the measurement when the measurement is started at the timing when the instruction is received, the predicted value being based on reference information that defines a change in the amount of drift over time, and the controller may start the measurement if the predicted value is less than a predetermined threshold, and avoid starting the measurement if the predicted value is equal to or greater than the threshold.

[0083] The scanning probe microscope according to the first aspect provides a technique for more reliably avoiding problems that may arise due to drift in the scanning probe microscope.

[0084] (Clause 2) In the scanning probe microscope according to paragraph 1, the controller may identify the earliest start timing at which the total amount of drift until the end of the measurement will be less than the threshold value, based on the reference information, and cause the measurement unit to start the measurement when the earliest start timing arrives.

[0085] According to the scanning probe microscope of the second aspect, even if the start of measurement is avoided at the timing when the measurement instruction is acquired, the measurement can be automatically started when the earliest start timing arrives.

[0086] (Clause 3) In the scanning probe microscope according to paragraph 1 or 2, the controller may identify the earliest start timing at which the total amount of drift until the end of the measurement is less than the threshold value, based on the reference information, and notify the user of the earliest start timing.

[0087] According to the scanning probe microscope according to the third aspect, even if the start of measurement is avoided at the timing when the measurement instruction is acquired, the user can recognize the earliest start timing.

[0088] (4) In the scanning probe microscope according to any one of paragraphs 1 to 3, the controller may calculate, as the predicted value, the product of the amount of drift per unit time and the length of time required for the measurement, in specifying the predicted value.

[0089] According to the scanning probe microscope of paragraph 4, the predicted value can be calculated in a simple manner. (paragraph 5) In the scanning probe microscope of paragraph 4, the controller may acquire the measurement conditions, and in specifying the predicted value, specify the length of time required for the measurement based on the measurement conditions as the time from the start to the end of the measurement.

[0090] According to the scanning probe microscope of paragraph 5, the information (predicted value) used to determine whether or not a measurement will be performed at the time when a measurement instruction is obtained is created according to the measurement conditions, and the result of the determination whether or not a measurement will be performed at the time when a measurement instruction is obtained is based on the measurement conditions.

[0091] (Item 6) In the scanning probe microscope according to item 5, the measurement conditions include at least one of the number of images acquired in the measurement, the scanning speed in the main scanning direction, and the number of pixels acquired in a direction intersecting the main scanning direction.

[0092] According to the scanning probe microscope of the sixth aspect, the result of the determination as to whether or not the measurement is to be performed at the timing when the measurement instruction is acquired can reflect the measurement conditions.

[0093] (Clause 7) In the scanning probe microscope according to any one of clauses 1 to 6, the controller may obtain a plurality of drift amounts corresponding to a plurality of timings, and create the reference information predicted from the plurality of drift amounts.

[0094] According to the scanning probe microscope according to the seventh aspect, the reference information can reflect the individual differences of the scanning probe microscope.

[0095] (Item 8) In the scanning probe microscope according to item 7, the reference information may be a quadratic curve obtained by quadratic curve approximation using the plurality of drift amounts.

[0096] According to the scanning probe microscope of item 8, reference information that appropriately represents changes in the amount of drift that are expected to occur in a typical scanning probe microscope can be created by a relatively simple calculation.

[0097] (Clause 9) In the scanning probe microscope according to any one of clauses 1 to 8, the controller may identify the maximum number of images for which the measurement can be started at the timing when the instruction is acquired, based on the reference information, and notify the user of the maximum number.

[0098] According to the scanning probe microscope of paragraph 9, the user can recognize the maximum number of images for which measurement can be started at the timing when the instruction is acquired.

[0099] (Clause 10) A method for controlling a scanning probe microscope according to one aspect is a method for controlling a scanning probe microscope that is implemented by a computer, and includes the steps of: acquiring an instruction to start a measurement; calculating a predicted value of a total amount of drift in the measurement when the measurement is started at the timing when the instruction is acquired; and judging whether to start the measurement based on the predicted value, wherein the predicted value is based on reference information that defines a change in the amount of drift over time; and wherein, in the judging step, if the predicted value is less than a predetermined threshold, the measurement is started, and if the predicted value is equal to or greater than the threshold, the start of the measurement is avoided.

[0100] The scanning probe microscope control method according to the tenth aspect provides a technique for more reliably avoiding problems that may arise due to drift in a scanning probe microscope.

[0101] (Clause 11) The method for controlling a scanning probe microscope according to Clause 10 may further include the steps of: identifying, based on the reference information, the earliest start timing at which the total amount of drift until the end of the measurement is less than the threshold; and causing the scanning probe microscope to start the measurement in response to the arrival of the earliest start timing.

[0102] According to the scanning probe microscope control method of paragraph 11, even if the start of measurement is avoided at the timing when the measurement instruction is acquired, the measurement can be automatically started when the earliest start timing arrives.

[0103] (Clause 12) The method for controlling a scanning probe microscope according to clause 10 or 11 may further include the steps of: identifying, based on the reference information, the earliest start timing at which the total amount of drift until the end of the measurement is less than the threshold; and notifying the earliest start timing.

[0104] According to the scanning probe microscope control method of paragraph 12, even if the start of measurement is avoided at the timing when the measurement instruction is acquired, the user can recognize the earliest start timing.

[0105] (Item 13) In the method for controlling a scanning probe microscope according to any one of Items 9 to 11, the step of calculating the predicted value may include calculating, as the predicted value, the product of the amount of drift per unit time and the length of time required for the measurement.

[0106] According to the scanning probe microscope control method of the thirteenth aspect, the predicted value can be calculated in a simple manner.

[0107] (Clause 14) The method for controlling a scanning probe microscope according to Clause 13 may further include a step of acquiring conditions for the measurement, and the step of calculating the predicted value may include specifying the length of time required for the measurement based on the conditions for the measurement as the time from the start to the end of the measurement.

[0108] According to the scanning probe microscope control method of paragraph 14, information (predicted value) used to determine whether or not a measurement will be performed at the time a measurement instruction is obtained is created in accordance with the measurement conditions, and the result of the determination as to whether or not a measurement will be performed at the time a measurement instruction is obtained is based on the measurement conditions.

[0109] (Item 15) In the method for controlling a scanning probe microscope according to Item 14, the measurement conditions may include at least one of the number of images acquired in the measurement, the scanning speed in the main scanning direction, and the number of pixels acquired in a direction intersecting the main scanning direction.

[0110] According to the scanning probe microscope control method of the fifteenth aspect, the result of the determination as to whether or not the measurement is to be performed at the timing when the measurement instruction is acquired can reflect the measurement conditions.

[0111] (Item 16) The method for controlling a scanning probe microscope according to any one of Items 10 to 15 may further comprise the step of creating the reference information based on a plurality of drift amounts corresponding to each of a plurality of timings.

[0112] According to the scanning probe microscope control method of paragraph 16, individual differences between scanning probe microscopes can be reflected in the reference information.

[0113] (Item 17) In the method for controlling a scanning probe microscope according to Item 16, the reference information may be a quadratic curve obtained by quadratic curve approximation using the plurality of drift amounts, and the predicted value may be an integral value of the quadratic curve from the start to the end of the measurement.

[0114] According to the scanning probe microscope control method of paragraph 17, reference information that appropriately represents changes in the amount of drift that are expected to occur in a typical scanning probe microscope can be created by relatively simple calculations.

[0115] (Clause 18) The method for controlling a scanning probe microscope according to any one of clauses 10 to 17 may further include the steps of identifying, based on the reference information, the maximum number of images for which the measurement can be started at the timing when the instruction is acquired, and notifying the maximum number.

[0116] According to the scanning probe microscope control method of paragraph 18, the user can recognize the maximum number of images for which measurement can be started at the timing when an instruction is acquired.

[0117] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is defined by the claims, not by the description of the above-described embodiments, and is intended to include all modifications within the meaning and scope of the claims. Furthermore, it is intended that each technique in the embodiments can be implemented alone or, if necessary, in combination with other techniques in the embodiments to the extent possible.

[0118] 1 Scanning probe microscope, 100 Measurement unit, 110 Sample, 111 Piezo scanner, 111xy XY scanner, 111z Z scanner, 112 Sample stage, 113 Cantilever, 114 Probe, 115 Laser diode, 119 Photodetector, 120 Displacement detection mechanism, 131 Feedback signal generator, 132 Computer, 133 Scanning signal generator, 134 Storage device, 135 Display device, 136 Input device, 150 Controller.

Claims

1. A scanning probe microscope comprising: a measurement unit including a measurement probe; and a controller for controlling the measurement unit, wherein, when the controller receives an instruction to start a measurement, it determines a predicted value of the total amount of drift in the measurement when the measurement is started at the timing when the instruction is received, the predicted value being based on reference information that defines the change in the amount of drift over time, and the controller starts the measurement if the predicted value is less than a predetermined threshold, and avoids starting the measurement if the predicted value is equal to or greater than the threshold.

2. The scanning probe microscope of claim 1, wherein the controller identifies the earliest start timing at which the total amount of drift until the end of the measurement will be less than the threshold value based on the reference information, and causes the measurement unit to start the measurement when the earliest start timing arrives.

3. The scanning probe microscope according to claim 1, wherein the controller identifies the earliest start timing at which the total amount of drift until the end of the measurement is less than the threshold value based on the reference information, and notifies the user of the earliest start timing.

4. A scanning probe microscope according to claim 1, wherein the controller, in specifying the predicted value, calculates the product of the amount of drift per unit time and the length of time required for the measurement as the predicted value.

5. A scanning probe microscope as described in claim 4, wherein the controller acquires the conditions of the measurement, and in specifying the predicted value, specifies the length of time required for the measurement based on the conditions of the measurement as the time from the start to the end of the measurement.

6. A scanning probe microscope according to claim 5, wherein the measurement conditions include at least one of the number of images acquired in the measurement, the scanning speed in the main scanning direction, and the number of pixels acquired in a direction intersecting the main scanning direction.

7. The scanning probe microscope according to claim 1, wherein the controller acquires a plurality of drift amounts corresponding to a plurality of timings, and creates the reference information predicted from the plurality of drift amounts.

8. The scanning probe microscope according to claim 7, wherein the reference information is a quadratic curve obtained by quadratic curve approximation using the plurality of drift amounts.

9. The scanning probe microscope according to claim 1, wherein the controller identifies the maximum number of images for which the measurement can be started at the timing when the instruction is acquired based on the reference information, and notifies the user of the maximum number.

10. A control method for a scanning probe microscope, implemented by a computer, comprising: a step of acquiring an instruction to start measurement; a step of calculating a predicted value of the total amount of drift in the measurement when the measurement is started at the timing when the instruction is acquired; and a step of determining whether to start the measurement based on the predicted value, wherein the predicted value is based on reference information that defines the change in the amount of drift over time, and in the determining step, if the predicted value is less than a predetermined threshold, the measurement is started, and if the predicted value is equal to or greater than the threshold, the start of the measurement is avoided.

11. A method for controlling a scanning probe microscope according to claim 10, further comprising the steps of: identifying the earliest start timing at which the total amount of drift until the end of the measurement will be less than the threshold value based on the reference information; and causing the scanning probe microscope to start the measurement in response to the arrival of the earliest start timing.

12. A method for controlling a scanning probe microscope according to claim 10, further comprising the steps of: identifying the earliest start timing at which the total amount of drift until the end of the measurement is less than the threshold value based on the reference information; and notifying the earliest start timing.

13. A method for controlling a scanning probe microscope according to claim 10, wherein the step of calculating the predicted value includes calculating the product of the amount of drift per unit time and the length of time required for the measurement as the predicted value.

14. A method for controlling a scanning probe microscope according to claim 13, further comprising a step of acquiring the conditions of the measurement, wherein the step of calculating the predicted value includes specifying the length of time required for the measurement based on the conditions of the measurement as the time from the start to the end of the measurement.

15. A method for controlling a scanning probe microscope according to claim 14, wherein the measurement conditions include at least one of the number of images acquired in the measurement, the scanning speed in the main scanning direction, and the number of pixels acquired in a direction intersecting the main scanning direction.

16. A method for controlling a scanning probe microscope according to claim 10, further comprising the step of creating the reference information based on a plurality of drift amounts corresponding to a plurality of timings.

17. A method for controlling a scanning probe microscope according to claim 16, wherein the reference information is a quadratic curve obtained by quadratic curve approximation using the plurality of drift amounts.

18. A method for controlling a scanning probe microscope as described in claim 10, further comprising the steps of: identifying the maximum number of images for which the measurement can be started at the timing when the instruction is acquired based on the reference information; and notifying the maximum number.

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