JP4130169B2 - Scanning probe microscope - Google Patents

Description

  The present invention relates to a scanning probe microscope, and more particularly to a scanning probe microscope having an operation state management function of a step-in method (“step-in” is a registered trademark) in which a probe approaches and retreats from a sample.

  A scanning probe microscope is conventionally known as a measurement apparatus having a measurement resolution capable of observing a fine object of atomic order or size. In recent years, scanning probe microscopes have been applied to various fields such as measurement of fine irregularities on the surface of a substrate or wafer on which a semiconductor device is made. There are various types of scanning probe microscopes depending on the detected physical quantity used for measurement. For example, there are a scanning tunnel microscope using a tunnel current, an atomic force microscope using an atomic force, a magnetic force microscope using a magnetic force, etc., and their application range is expanding.

  Among these, the atomic force microscope is suitable for detecting fine irregularities on the surface of the sample with high resolution, and has a proven record in the fields of semiconductor substrates and disks. Recently, it has also been used for in-line automatic inspection processes.

  The atomic force microscope includes a measuring device portion based on the principle of the atomic force microscope as a basic configuration. Usually, a tripod type or tube type XYZ fine movement mechanism formed using a piezoelectric element is provided, and a cantilever having a probe tip formed at the tip is attached to the lower end of the XYZ fine movement mechanism. The tip of the probe faces the surface of the sample. For example, an optical lever type optical detection device is provided for the cantilever. That is, laser light emitted from a laser light source (laser oscillator) disposed above the cantilever is reflected by the back surface of the cantilever and detected by the photodetector. When the cantilever is twisted or bent, the incident position of the laser beam in the photodetector changes. Therefore, when a displacement occurs between the probe and the cantilever, the direction and amount of the displacement can be detected by the detection signal output from the photodetector. As for the configuration of the above atomic force microscope, a comparator and a controller are usually provided as a control system. The comparator compares the detection voltage signal output from the photodetector with the reference voltage and outputs a deviation signal. The controller generates a control signal so that the deviation signal becomes zero, and gives this control signal to the Z fine movement mechanism in the XYZ fine movement mechanism. In this way, a feedback servo control system that maintains a constant distance between the sample and the probe is formed. With the above configuration, the probe can be scanned while following the fine irregularities on the sample surface, and the shape of the probe can be measured (see, for example, Patent Document 1).

  At the time when the atomic force microscope was invented, measurement of surface fine shapes on the order of nm (nanometer) or less was a central issue by utilizing its high resolution. However, at present, the scanning probe microscope has been expanded in its range of use to in-line automatic inspection in which inspection is performed at an intermediate stage of an in-line manufacturing apparatus for semiconductor devices. In such a situation, in the actual inspection process, it is required to inspect the surface of the substrate or wafer at predetermined intervals. For this reason, automatic measurement for rapidly detecting the surface of a substrate or wafer is also being demanded.

  An example of a technique for quickly detecting the surface of a substrate or wafer using an atomic force microscope is a step-in method. In the step-in method, the probe is brought close to the sample surface at each of a plurality of measurement points set at predetermined intervals, the shape of the approached surface is measured, and then the probe is retracted. Then, the operation of moving the probe by a distance corresponding to the predetermined interval, approaching the surface again, measuring the surface, and retracting is repeated.

  The operation of the step-in method and the state of the cantilever will be described with reference to FIGS. 7A, the probe 100 is in contact with the surface of the measurement sample 103 and a Z-axis fine movement mechanism (not shown) moves the cantilever base 102 to the sample side. FIG. 7B shows a normal retracted state, which is generated when the Z-axis fine movement mechanism moves the cantilever base 102 away from the sample 103. FIG. 7C shows an abnormal retreat state. In FIG. 7C, the probe 100 is adsorbed to the sample surface 103 even though the cantilever base 102 is retracted to the normal retracted position. Therefore, the cantilever 101 is in a state of bending toward the sample side. FIG. 8 shows an example of the step-in operation of the probe 100 with respect to the sample surface 103, and the arrows indicate the movement trajectory of the probe. In FIG. 8, (1) is an approach operation, and when the approach is completed, the state of FIG. (2) in FIG. 8 is the evacuation state, and when the evacuation is completed normally, the state shown in FIG. 7 (b) is obtained. In FIG. 8, (3) shows a state where the XY fine movement mechanism (not shown) is used to move to the position of the next measurement point. In the step-in operation, the above operations (1) to (3) are repeated for each measurement point at a constant interval.

  When the conventional scanning atomic force microscope performs the measurement operation by the step-in method as described above, there is a case where the retreat of (2) shown in FIG. 8 is not normally performed. For example, in the case where the probe attracting force on the sample surface is strong, even if the cantilever base 102 moves away from the sample surface, the probe 100 provided at the tip of the soft cantilever 101 may remain adsorbed on the sample surface. is there. These are the states of FIG. 7C described above. If the movement of (3) in FIG. 8 is performed in a state where such an abnormal retreat operation has occurred, there is a problem that the image is disturbed or the probe is damaged.

As described above, the conventional step-in scanning probe microscope does not manage the state of the tip when the probe is retracted. There is a problem that it cannot be distinguished whether the image is disturbed due to adsorption or the like.
Japanese Patent No. 3364531

  The problem of the present invention is that in a step-in scanning probe microscope, when image disturbance due to probe adsorption occurs, it is not possible to distinguish between the actual sample shape and the image disturbance due to adsorption or the like. Is to eliminate.

  In view of the above-described problems, the object of the present invention is to realize the tip state monitoring when the probe is retracted when the sample is measured by the step-in method so that the content of the image can be accurately grasped. Another object of the present invention is to provide a scanning probe microscope.

  In order to achieve the above object, a scanning probe microscope according to the present invention is configured as follows.

The first scanning probe microscope (corresponding to claim 1) includes a cantilever having a probe at the tip, and moves the cantilever to move the probe closer to or away from the sample to obtain surface information of the sample. A scanning probe microscope, a displacement detection device for detecting the displacement amount of the cantilever, a monitor means for monitoring a detection signal output from the displacement detection device after the probe retracting operation is completed, and a detection monitored by the monitor means A probe retracting state confirmation unit is configured to include a determination unit that determines whether the probe retracting operation is normal or abnormal based on the signal .

In the second scanning probe microscope (corresponding to claim 2 ), in the first apparatus configuration described above, preferably, when the determination unit determines that the probe retracting operation is abnormal, an alarm is issued. It is characterized by having an alarm / stop unit to stop the measurement operation.

  Since the scanning probe microscope according to the present invention includes a probe retraction state confirmation unit for confirming normality or abnormality of the probe retraction operation, in the step-in scanning probe microscope, the needle tip state when the probe is retreated It is possible to monitor. In conventional step-in scanning probe microscopes, the tip state management is not performed when the probe is retracted. I can't tell if it's a disturbance. On the other hand, the configuration according to the present invention includes a displacement detection device that detects the displacement amount of the cantilever, and the probe retraction state confirmation unit outputs a detection signal output from the displacement detection device after the probe retraction operation is completed. A monitor unit for monitoring and a determination unit for determining whether the retracting operation of the probe is normal or abnormal based on the detection signal monitored by the monitor unit, so that image disturbance due to probe adsorption is accurately detected Can be detected. In particular, when the determination unit determines that the probe retracting operation is abnormal, it has an alarm / stop unit that issues an alarm and stops the measurement operation, so it can reliably detect image disturbance due to probe adsorption, Further, when the probe sticking occurs, the measurer is notified by an alarm and the measuring operation is stopped to prevent the probe from being damaged.

  According to the present invention, in the step-in type scanning probe microscope, the retracted state of the probe can be confirmed, and the breakage of the probe and the disturbance of the measurement data can be prevented.

  Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

  The configuration of a scanning probe microscope (SPM) according to the present invention will be described with reference to FIG. This scanning probe microscope assumes an atomic force microscope (AFM) as a typical example.

  A sample stage 11 is provided in the lower part of the scanning probe microscope. A sample 12 is placed on the sample stage 11. The sample stage 11 is a mechanism for changing the position of the sample 12 in a three-dimensional coordinate system 13 composed of orthogonal X, Y, and Z axes. The sample stage 11 includes an XY stage 14, a Z stage 15, and a sample holder 16. The sample stage 11 is normally configured as a coarse movement mechanism that causes displacement (position change) on the sample side. On the upper surface of the sample holder 16 of the sample stage 11, the sample 12 having a relatively large area and a thin plate shape is placed and held. The sample 12 is, for example, a substrate or a wafer on which a semiconductor device is manufactured on the surface. The sample 12 is fixed on the sample holder 16. The sample holder 16 includes a sample fixing chuck mechanism.

  A specific configuration example of the sample stage 11 will be described with reference to FIG. In FIG. 2, 14 is an XY stage, and 15 is a Z stage. The XY stage 14 is a mechanism for moving the sample on the horizontal plane (XY plane), and the Z stage 15 is a mechanism for moving the sample 12 in the vertical direction. The Z stage 15 is mounted and mounted on the XY stage 14, for example.

  The XY stage 14 includes two Y-axis rails 201 arranged in parallel in the Y-axis direction, a Y-axis motor unit composed of a Y-axis motor 202 and a Y-axis driving force transmission mechanism 203, and an X-axis direction. The X-axis mechanism unit includes two parallel X-axis rails 204, an X-axis motor 205, and an X-axis driving force transmission mechanism 206. By the XY stage 14, the Z stage 15 is arbitrarily moved in the X-axis direction or the Y-axis direction. The Z stage 15 is provided with a drive mechanism for raising and lowering the sample holder 16 in the Z-axis direction. In FIG. 2, the drive mechanism is hidden and not shown. A chuck mechanism 207 for fixing the sample 12 is provided on the sample holder 16. As the chuck mechanism 207, a mechanical type or a mechanism using an action such as adsorption or electrostatic is usually used.

  In FIG. 1, an optical microscope 18 having a drive mechanism 17 is disposed above the sample 12. The optical microscope 18 is supported by a drive mechanism 17. The drive mechanism 17 includes a focus Z-direction moving mechanism 17a for moving the optical microscope 18 in the Z-axis direction and an XY-direction moving mechanism 17b for moving in the XY axial directions. As an attachment relationship, the Z-direction moving mechanism 17a moves the optical microscope 18 in the Z-axis direction, and the XY-direction moving mechanism 17b moves the units of the optical microscope 18 and the Z-direction moving mechanism 17a in the respective XY axes. Although the XY direction moving mechanism portion 17b is fixed to the frame member, the frame member is not shown in FIG. The optical microscope 18 is disposed with its objective lens 18a facing downward, and is disposed at a position facing the surface of the sample 12 from directly above. A camera 19 is attached to the upper end of the optical microscope 18. The camera 19 captures and acquires an image of a specific area of the sample surface captured by the objective lens 18a, and outputs image data.

  On the upper side of the sample 12, a cantilever 21 having a probe 20 at the tip is arranged in a close state. The cantilever 21 is fixed to the attachment portion 22. For example, the attachment portion 22 is provided with an air suction portion (not shown), and the air suction portion is connected to an air suction device (not shown). The cantilever 21 is fixed and mounted by adsorbing the base portion having a large area by the air suction portion of the mounting portion 22.

  The attachment portion 22 is attached to a Z fine movement mechanism 23 that causes a fine movement operation in the Z direction. Further, the Z fine movement mechanism 23 is attached to the lower surface of the cantilever displacement detection unit 24.

  The cantilever displacement detector 24 has a configuration in which a laser light source 26 and a light detector 27 are attached to a support frame 25 in a predetermined arrangement relationship. The cantilever displacement detector 24 and the cantilever 21 are held in a certain positional relationship, and the laser light 28 emitted from the laser light source 26 is reflected by the back surface of the cantilever 21 and enters the photodetector 27. The cantilever displacement detector constitutes an optical lever type optical detector. When the cantilever 21 undergoes deformation such as twisting or bending by the optical lever type optical detection device, the deformation can be detected.

  The cantilever displacement detector 24 is attached to an XY fine movement mechanism 29. The XY fine movement mechanism 29 moves the cantilever 21, the probe 20 and the like at a minute distance in the XY axial directions. At this time, the cantilever displacement detector 24 is moved simultaneously, and the positional relationship between the cantilever 21 and the cantilever displacement detector 24 is unchanged.

  In the above description, the Z fine movement mechanism 23 and the XY fine movement mechanism 29 are usually composed of piezoelectric elements. The Z fine movement mechanism 23 and the XY fine movement mechanism 29 cause displacement of the probe 20 by a minute distance (for example, several to 10 μm, maximum 100 μm) in each of the X axis direction, the Y axis direction, and the Z axis direction.

  In the above mounting relationship, the observation field of view by the optical microscope 18 includes the surface of a specific region of the sample 12 and the tip (back) of the cantilever 21 including the probe 20.

  Next, a control system of the scanning probe microscope will be described. As a configuration of the control system, a comparator 31, a controller 32, a first control device 33, and a second control device 34 are provided. The controller 32 is a controller for realizing in principle a measurement mechanism using, for example, an atomic force microscope (AFM). The first control device 33 is a control device for driving control of each of a plurality of drive mechanisms, and the second control device 34 is a higher-level control device.

  The comparator 31 compares the voltage signal Vd output from the photodetector 27 with a preset reference voltage (Vref) and outputs a deviation signal s1 (s1 = Vref−Vd). Usually, when no force is applied to the probe, Vd indicates a voltage in the vicinity of 0 V, and the reference voltage (Vref) is set to a plus number V in the normal measurement state. When a repulsive force is applied to the probe and the cantilever is deformed to the anti-sample side, Vd is displaced to the plus side. When an attractive force is applied to the probe and the cantilever is deformed to the sample side, Vd is deformed to the minus side. The controller 32 generates a control signal s2 so that the deviation signal s1 becomes 0, and gives this control signal s2 to the Z fine movement mechanism 23. Upon receiving the control signal s2, the Z fine movement mechanism 23 adjusts the height position of the cantilever 21, and keeps the distance between the probe 20 and the surface of the sample 12 at a constant distance. The control loop from the photodetector 27 to the Z fine movement mechanism 23 detects the deformation state of the cantilever 21 with the optical lever type optical detection device while scanning the sample surface with the probe 20. This is a feedback servo control loop for maintaining the distance to the sample 12 at a predetermined constant distance determined based on the reference voltage (Vref). By this control loop, the probe 20 is kept at a constant distance from the surface of the sample 12, and when the surface of the sample 12 is scanned in this state, the uneven shape of the sample surface can be measured.

  Next, the 1st control apparatus 33 is provided with the following function parts.

  The position of the optical microscope 18 is changed by a driving mechanism 17 including a focusing Z-direction moving mechanism 17a and an XY-direction moving mechanism 17b. The first control device 33 includes a first drive control unit 41 and a second drive control unit 42 for controlling the operations of the Z direction moving mechanism unit 17a and the XY direction moving mechanism unit 17b.

  The sample surface and the image of the cantilever 21 obtained by the optical microscope 18 are picked up by the camera 19 and taken out as image data. Image data obtained by the camera 19 of the optical microscope 18 is input to the first control device 33 and processed by the internal image processing unit 43.

  In the feedback servo control loop including the controller 32 and the like, the control signal s2 output from the controller 32 means a height signal of the probe 20 in the scanning probe microscope (atomic force microscope). . Information related to the change in the height position of the probe 20 can be obtained by the height signal of the probe 20, that is, the control signal s2. The control signal s2 including the height position information of the probe 20 is given to the Z fine movement mechanism 23 for driving control as described above, and is taken into the data processing unit 44 in the control device 33.

  The voltage signal Vd output from the photodetector 27 of the cantilever displacement detector (displacement detector) 24 is monitored by the monitor 49 after the probe retracting operation is completed.

  The scanning of the sample surface with the probe 20 in the measurement region on the surface of the sample 12 is performed by driving the XY fine movement mechanism 29. The drive control of the XY fine movement mechanism 29 is performed by an XY scanning control unit 45 that provides the XY fine movement mechanism 29 with an XY scanning signal s3.

  The XY stage 14 and the Z stage 15 of the sample stage 11 are driven by an X drive control unit 46 that outputs an X direction drive signal, a Y drive control unit 47 that outputs a Y direction drive signal, and a Z direction that outputs a Z direction drive signal. It is controlled by the drive control unit 48.

  The first control device 33 includes a storage unit that stores and saves the set control data, the input optical microscope image data, the data related to the height position of the probe, and the like as necessary.

  A second control device 34 positioned above the first control device 33 is provided. The second control device 34 stores and executes a normal measurement program and sets and stores a normal measurement condition, stores and executes an automatic measurement program and sets and stores the measurement condition, stores measurement data, and displays an image of the measurement result. Processing such as processing and display on the display device (monitor) 35 is performed. In particular, in the case of the present invention, the step-in method includes a process of confirming the probe retracting state for confirming normality or abnormality of the probe retracting operation, and the displacement detection is performed after the probe retracting operation is completed. A detection signal output from the apparatus is monitored, and a program for determining whether the probe retracting operation is normal or abnormal based on the monitored detection signal is provided. Further, when it is determined that the probe retracting operation is abnormal, it has a function of issuing an alarm and stopping the measuring operation. Furthermore, it can be configured to have a communication function, and can have a function to communicate with an external device.

  Since the second control device 34 has the above function, the second control device 34 includes a CPU 51 that is a processing device and a storage unit 52. The storage unit 52 stores and saves the above programs, condition data, and the like. Further, the CPU 51 and the storage unit 52 realize the function of the determination unit described later. Further, the second control device 34 includes an image display control unit 53 and a communication unit. In addition, an input device 36 is connected to the second control device 34 via an interface 54 so that programs, conditions, data, and the like stored in the storage unit 52 can be set and changed by the input device 36. It has become. Further, the second control device 34 is functionally realized with a determination unit and an alarm / stop unit, and an alarm 37 and a stop device 38 are connected via an interface 56. The determination unit of the second control device 34 determines whether the retracted state of the probe 20 is normal or abnormal based on the monitor signal from the monitor unit 49. When the determination unit determines that the retracted state of the probe 20 is abnormal, the determination unit causes the alarm 37 to be alerted via an alarm / stop unit, which will be described later, and the measurement operation is stopped by the stop device 38.

  The CPU 51 of the second control device 34 provides higher-level control commands and the like to each functional unit of the first control device 33 via the bus 55, and the image processing unit 43, the data processing unit 44, and the monitor unit 49. Image data, data related to the height of the probe, and the like.

  The determination unit for determining whether the probe retracting operation is normal or abnormal based on the detection signal monitored by the monitor unit 49, and the alarm / stop unit are functional means in the CPU 51 of the second control device 34 as described above. Configured as As shown in FIG. 4, the probe retracted state confirmation device 60 is configured by the determination unit 61 in the second control device 34 and the monitor unit 49 in the first control device.

  The alarm / stop unit 57 shown in FIG. 4 is a device that issues a warning via the interface 57 and stops the measurement operation when the determination unit 61 determines that the probe retracting operation is abnormal. .

  Next, the basic operation of the scanning probe microscope (atomic force microscope) will be described.

  The tip of the probe 20 of the cantilever 21 is made to face a predetermined region on the surface of the sample 12 such as a semiconductor substrate placed on the sample stage 11. Normally, the probe 20 is brought close to the surface of the sample 12 by the Z stage 15 which is a probe approach mechanism, and an atomic force is applied to cause the cantilever 21 to bend and deform. The amount of bending due to the bending deformation of the cantilever 21 is detected by the optical lever type optical detection device described above. In this state, the sample surface is scanned (XY scan) by moving the probe 20 relative to the sample surface. The XY scanning of the surface of the sample 12 by the probe 20 is performed by moving (finely moving) the probe 20 side by the XY fine movement mechanism 29 or by moving (coarsely moving) the sample 12 side by the XY stage 14. This is done by creating a relative movement relationship in the XY plane between the sample 12 and the probe 20.

  The movement on the probe 20 side is performed by giving an XY scanning signal s3 related to XY fine movement to an XY fine movement mechanism 29 including a cantilever 21. The scanning signal s3 related to the XY fine movement is given from the XY scanning control unit 45 in the first control device 33. On the other hand, the movement on the sample side is performed by giving drive signals from the X drive control unit 46 and the Y drive control unit 47 to the XY stage 14 of the sample stage 11.

  The XY fine movement mechanism 29 is configured using a piezoelectric element, and can perform scanning movement with high accuracy and high resolution. Further, the measurement range measured by the XY scanning by the XY fine movement mechanism 29 is limited by the stroke of the piezoelectric element, and therefore is a range determined by a distance of about 100 μm at the maximum. According to the XY scanning by the XY fine movement mechanism 29, a minute range is measured. On the other hand, since the XY stage 14 is usually configured using an electromagnetic motor as a drive unit, the stroke can be increased to several hundred mm. According to the XY scanning by the XY stage, a wide range is measured.

  As described above, while the predetermined measurement area on the surface of the sample 12 is scanned with the probe 20, the amount of bending of the cantilever 21 (the amount of deformation due to bending) is controlled based on the feedback servo control loop. I do. The amount of bending of the cantilever 21 is controlled so as to always coincide with the reference target amount of bending (set by the reference voltage Vref). As a result, the distance between the probe 20 and the surface of the sample 12 is maintained at a constant distance. Accordingly, the probe 20 moves while tracing the fine uneven shape (profile) on the surface of the sample 12, and the fine uneven shape on the surface of the sample 12 can be measured by obtaining the probe height signal.

  For example, as shown in FIG. 3, the scanning probe microscope as described above is incorporated as an automatic inspection process 92 for inspecting a substrate (wafer) at an intermediate stage of an in-line manufacturing apparatus of a semiconductor device (LSI). When a substrate (sample 12) to be inspected is unloaded from the production process step 91 in the previous stage by a substrate transfer device (not shown) and placed on the substrate holder 16 of the scanning probe microscope (SPM) in the automatic inspection step 92, scanning is performed. A microprotrusion shape of a predetermined area on the substrate surface is automatically measured by a scanning probe microscope, and the pass / fail of the processing of the substrate manufacturing in the previous stage is determined. Thereafter, the substrate is transported again to the subsequent manufacturing processing step 93 by the substrate transfer device. The

  Next, the probe retraction state confirmation unit of the scanning probe microscope will be described with reference to FIGS.

  FIG. 4 is a block diagram of the probe retraction state confirmation unit 60 described above. The probe retraction state confirmation unit 60 includes a monitor unit 49 and a determination unit 61. The monitor unit 49 is provided in the first control device 33, monitors the detection signal output from the light detector 27 after the retracting operation of the probe 20 is completed, and outputs the displacement signal to the determination unit 61. The determination unit 61 outputs an adsorption determination signal to the alarm / stop unit 57 when determining that the probe 20 is in an adsorbed state on the sample surface.

  FIG. 5 shows only the determination unit 61 and the alarm / stop unit 57 in the computer configuration of the second control device 34 described above. The determination unit 61 includes an input unit 62 and an output unit 63, and the CPU 51 and the storage unit 52 described above. In the determination unit 61, a predetermined value for determining whether or not the probe is in the suction state is stored in the storage area 64 in the storage unit 52. The storage area 65 stores processing programs (determination program and alarm / stop program). The determination unit 61 stores in advance the displacement signal from the monitor unit 49 in the normal retracted state in the storage unit 52 as a signal of the photodetector in the normal state, and from the monitor unit 49 in the retracted state at the time of measurement. The absolute value of the difference signal and the signal in the normal state stored in the storage unit is obtained, and if the absolute value is smaller than the predetermined value, it is determined that it is normal, and a normal value signal, for example, zero is displayed as an alarm / stop unit. If the absolute value is larger than the predetermined value, it is determined that the probe is attracted, and an abnormal signal, for example, 1 is output to the alarm / stop unit 57. Note that the signal of the photodetector in the normal state may be stored whenever the signal in the normal state can be detected. It is preferably performed immediately before the sample is approached.

  The alarm / stop unit 57 is a functional part that outputs a warning signal and stops the measurement operation when the determination unit 61 determines that the retracting operation of the probe 20 is abnormal. When the signal from the determination unit 61 is zero, this functional part issues an alarm-off signal to the alarm 37 via the interface 56, issues a measurement operation continuation signal, and maintains the measurement operation continuation state. When the signal from the determination unit 61 is 1, an alarm-on signal is output to the alarm 37 and a measurement operation stop signal is output to the stop device 38. As a result, when the alarm sounds, it can be determined that the probe is in the probe adsorption state, and the measurement operation is automatically stopped, so that the probe can be prevented from being damaged.

  Next, the effect | action of this embodiment is demonstrated using the flowchart of FIG. 6 corresponding to the processing program memorize | stored in the memory | storage area | region 65 which concerns on the determination part 61 and the warning / stop part 57. FIG. The processing program starts with the start of measurement, and sequentially performs an approach operation (step S10), an SPM measurement (step S11), and a retreat operation (step S12). After executing the evacuation operation in step S12, the monitor unit 49 monitors the signal Vd of the photodetector 27 (step S13). A difference DS (DS = Vd−Vd_usual) between the monitored signal and the signal Vd_usual of the photodetector 27 in the normal state stored in the storage unit is calculated (step S14). The CPU compares the difference DS with a predetermined value stored in the storage area 64 of the storage unit 52 (step ST15). As a result, when the absolute value of the difference DS is smaller than the predetermined value, the movement to the next measurement point (step ST16). Thereafter, it is determined whether or not the measurement is finished (step S17). If the measurement is not finished, the process returns to step S10 again to perform the process. If the measurement is finished, the execution of the processing program is finished. If the absolute value of the difference DS is greater than or equal to a predetermined value in step S15, 1 is output to the alarm 37 and the stop device 38. When the signal is 1, the alarm / stop unit 57 operates, outputs an alarm signal to the alarm 37, and outputs a measurement operation stop signal to the stop device 38 to stop the measurement operation (step S18).

  As described above, when the determination unit 61 determines that the probe retracting operation is abnormal, the alarm / stop unit 57 that issues an alarm and stops the measurement operation, and the alarm 37 and the stop device 38 that output the alarm are provided. Therefore, it is possible to reliably detect the disturbance of the image due to the probe sticking, and when the probe sticking occurs, the measurement person is notified with an alarm and the measuring operation is stopped to prevent the probe from being damaged.

  In the description of the above-described embodiment, an optical microscope is used for wide-area observation. Instead, various types such as a scanning electron microscope and a laser microscope can be used.

Configurations described implementation form of the shape, for merely present invention is schematically illustrated enough to understand and implement for the size and positional relationships, also numerical values and compositions (materials) Is just an example. Therefore, the present invention is not limited to the embodiment described above, and can be modified in various forms without departing from the scope of the technical idea shown in the claims.

  The present invention is used as a step-in scanning probe microscope capable of confirming the retracted state of the probe and preventing damage to the probe and disturbance of measurement data.

It is a block diagram which shows the whole structure of the scanning probe microscope which concerns on this invention. It is a perspective view which shows the specific structure of a sample stage. It is the block diagram which showed the structure by which the scanning probe microscope which concerns on this invention is used as an in-line automatic test process. It is a block block diagram of a probe evacuation state confirmation part. It is a block block diagram which shows a determination part and a warning / stop part. It is a flowchart corresponding to the processing program of a determination part and an alarm / stop part. It is a figure which shows the state of a cantilever in a step-in system, and is a figure which shows (a) contact state, (b) normal evacuation state, and (c) abnormal evacuation state. It is a figure which shows operation | movement of the step-in type cantilever.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Sample stage 12 Sample 16 Sample holder 17 Drive mechanism 18 Optical microscope 19 Camera 20 Probe 21 Cantilever 22 Mounting part 23 Z fine movement mechanism 29 XY fine movement mechanism 33 1st control apparatus 34 2nd control apparatus 34 Monitor part 55 Alarm / stop apparatus 60 Probe retraction state confirmation unit 61 Judgment unit

Claims (2)

In a scanning probe microscope comprising a cantilever having a probe at the tip, moving the cantilever to move the probe closer to or away from the sample, and obtaining surface information of the sample,
A displacement detection device that detects the displacement amount of the cantilever, a monitor unit that monitors a detection signal output from the displacement detection device after completion of the retracting operation of the probe, and a detection signal monitored by the monitor unit A probe retraction state confirmation unit comprising a determination unit that determines whether the probe retraction operation is normal or abnormal .
A scanning probe microscope characterized by the above. The determination means by the scanning probe microscope according to claim 1, characterized by comprising an alarm and stop means for stopping the measurement operation by issuing an alarm when the retracting operation of the probe is determined to be abnormal .

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