JP2001099773A - Scanning probe microscope and its measuring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a scanning probe microscope and its measuring method capable of shortening the measuring time, reducing wear of a probe, and preventing degradation of measurement precision caused by the wear of the probe in measuring an object having a large area and a high aspect ratio in high resolution. SOLUTION: This scanning probe microscope comprises a probe 14 for facing a sample 13, displacement detecting mechanisms 22, 23 for detecting displacement of the probe in the vertical direction, an XY scanner 12 for scanning a wide area, a single piezoelectric element 16 for displacing the probe in the vertical direction, an approach and retreat signal supplying device 35 for outputting a voltage signal for approaching and retreating the probe to and from the surface of the sample in a sampling position, and a servo control device 30 for maintaining a reference distance between the sample and the probe based on a detection signal from the displacement detecting mechanism. The probe scans the surface while maintaining the reference distance between the probe and the sample in the sampling position, to measure a recessed and projected shape of the surface of the sample. The approach and retreat signal s01 is superimposed to a signal s0 for determining the reference distance in a servo control loop, and servo control is continued.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning probe microscope and a measuring method, and more particularly to a CMP method in a semiconductor manufacturing field.
The present invention relates to a scanning probe microscope equipped with a probe approach / retreat configuration that enables an observation field to be enlarged for polishing evaluation in a (chemical mechanical polishing) process and enables measurement of an object having a high aspect ratio, and a measurement method therefor. .

[0002]

2. Description of the Related Art A scanning probe microscope utilizes an atomic force acting between a probe and the surface of a sample, such as an uneven surface of a semiconductor substrate (wafer), as typified by an atomic force microscope. It is used for measuring and observing fine irregularities. The scanning range on the sample surface is such that a piezoelectric element is generally used as a scanning actuator, and the displacement obtained by the piezoelectric element is, for example, a stroke of the order of μm (micrometer), at most about 100 μm, and is extremely fine. It is. On the other hand, in recent years, it has been desired that a scanning probe microscope can scan a wide area to observe a wide area. Specifically, with the miniaturization of the object to be manufactured in the semiconductor manufacturing process, the flatness of the surface of the semiconductor substrate or the flatness of the surface of the film deposited on the substrate surface in the manufacturing process of various semiconductor devices. The need for evaluation is increasing. In particular, in the evaluation of the flattening process using the CPM, it is required to measure the uneven shape in a wide range from several mm (millimeter) to several tens mm with a resolution of nm (nanometer).

As an apparatus capable of observing a large field of view with fine measurement as described above, an apparatus disclosed in, for example, Japanese Patent Application Laid-Open No. 10-62158 has been proposed instead of a scanning probe microscope. . The apparatus disclosed in this publication is a surface roughness meter, and in the section of the prior art, a stylus type and an optical surface roughness meter are described.
The stylus type surface roughness meter makes a needle member come into contact with the surface of a sample, and scans the sample surface with the needle member to measure the uneven shape of the sample surface. The movement of the needle member is detected by a differential transformer type detector. On the other hand, with an optical surface roughness meter, the irregular shape of the sample surface is detected by an optical displacement detection system. The surface roughness meter is provided with a motor-driven XY stage for moving the sample in the XY directions, and is configured so that the surface of the sample can be observed in a wide area with an inherently mechanical structure. The needle uses a cantilever used in an atomic force microscope as the needle in the above-mentioned publication because the needle contacts the sample surface, the sample surface is deformed and broken by a mechanical structure, and the resolution is low. Suggest that you
It is proposed to use the features of atomic force microscope for surface roughness meter.

Further, according to the scanning tunneling microscope disclosed in Japanese Patent Application Laid-Open No. 2-5340, as shown in FIG. ) Alone to acquire data by approaching the probe to the sample surface, and when moving, move the probe by retracting the probe. by this,
A large observation area can be measured, and the measurement can be performed in a short time without causing abrasion of the probe or collision with the sample surface.

[0005]

As described above, in recent years, there has been a demand for a scanning probe microscope capable of observing fine irregularities of a sample in a large field of view. In the measurement / observation of a conventional scanning probe microscope that inherently measures micrometer-level irregularities, if the scanning range is expanded to a range of millimeters, the moving distance of the probe on the sample surface becomes longer. According to the conventional normal measurement method, during the movement, the tip moves along the surface with its tip being very close to the sample surface, and when the tip contacts the sample surface. Therefore, wear of the tip of the probe becomes remarkable. As a result, a problem that measurement accuracy is lowered is raised. In addition, when the probe is worn, the entire length of the probe is shortened, and accordingly, the height information obtained by the probe includes an error, and the resolution in the surface area to be measured decreases. . Furthermore, as the amount of wear of the probe increases,
The problem that the throughput of measurement is reduced due to frequent probe replacement is also raised. The above-mentioned JP-A-10-
In the apparatus disclosed in Japanese Patent No. 62158, the contact pressure applied to the sample surface is reduced as compared with the conventional surface roughness meter by using the probe of the cantilever of the atomic force microscope in the surface roughness meter. Although he claims that the effect has been achieved, even with this apparatus, it is difficult to solve the above problem simply by using the cantilever of an atomic force microscope.

When measuring a wide range at a high resolution of nm level according to an atomic force microscope or the like, as described above, a piezoelectric element is conventionally used as a scanning actuator and a probe scanning speed is 10 μm / m. Seconds,
It was very time consuming. For example, 10mm x 1
When measuring at 256 × 256 points by scanning a range of 0 mm, the measurement time is about 142 hours (512000 seconds)
Becomes Further, as described above, when measuring over a wide area of 10 mm × 10 mm at 256 × 256 measurement points,
In spite of acquiring the surface data once every 40 μm, according to the conventional measurement method, the probe must be moved so as to follow the unevenness of the sample surface even between the measurement points. This leads to poor measurement efficiency.

In order to avoid the above problem, generally,
The probe is brought close to the sample surface only at the measurement point for obtaining the measurement data, that is, the sampling position, and the height position of the probe with respect to the sample surface is held at the set reference position based on the servo control system. The interval is a section for movement, during which the probe is retracted from the sample surface,
A configuration in which movement is performed in a separated state can be easily considered. As described above, this configuration is disclosed in
No. 40 discloses this. FIG. 6 shows an example of a moving state based on this configuration. In this figure, 101 is a probe, 102 is a locus of movement of the probe 101, 103 is a sampling position,
102a indicates an approaching operation, 102b indicates a retreating operation, and 102c indicates a movement away from the sample surface 104.
In such a configuration, since the probe 101 is moved like the above-described movement locus 102 by using the piezoelectric element, there is a problem in that the operation speed of each of the approaching operation 102a and the retreating operation 102b and the accuracy regarding the position are problematic. Become.

Further, the configuration of the scanning probe microscope disclosed in Japanese Patent Laid-Open No. 2-5340 raises the following important problem. As described above, the scanning probe microscope disclosed in this publication is a scanning tunnel microscope.
In a scanning probe microscope, the probe approaches the sample surface,
By keeping the tunnel current flowing between the probe and the sample at a predetermined fixed amount, a servo control system for maintaining the distance between the probe and the sample at a predetermined constant distance is formed. Then, in order to cause the probe to retreat at a position other than the sampling position, it is necessary to interrupt the servo control at the time of retreat. Because, even if a retract signal is given to the actuator for controlling the height of the probe, if the servo control is continued,
This is because the distance between the probe and the sample is kept constant, so that the evacuation operation cannot be performed. Therefore, when moving to the next sampling position and bringing the probe closer to the sample surface,
As shown in the operation explanatory time charts of FIGS. 5 and 9, a triangular drive signal is generated intermittently to control the position of the probe in the height direction slowly and carefully. There is a problem that the operation has to be performed, and it takes time to approach. Further, since such an approach operation must be performed, control of the operation becomes complicated.

Furthermore, in recent semiconductor manufacturing processes, a scanning probe microscope capable of observing an uneven shape having a high aspect ratio has been required with the miniaturization of an object formed on the surface of a substrate. For example, a hole formed for interlayer wiring called a contact hole has an opening of 0.2 μm and a depth of 1 μm. There is a need for a scanning probe microscope capable of measuring the shape of such a high aspect ratio hole. The probe in the scanning probe microscope necessarily has a thin and long shape. For example, a diameter of 0.1 μm, a length of 1 μm, and a tip radius of 0.01
A probe having a high aspect ratio such as μm is used. In the measurement using the probe having such a high aspect ratio, the measurement time becomes long. In addition, when performing measurement using such a probe, if the servo control is interrupted by the approach / retreat operation of the probe to / from the sample surface, there is a high possibility that the probe will break.

An object of the present invention is to provide a scanning probe microscope having a structure for performing an approach / retreat operation based on a state in which servo control is continued, to measure a narrow area or a wide area,
Alternatively, measurement of a sample with a high aspect ratio can be performed with high accuracy.
An object of the present invention is to provide a scanning probe microscope which can be performed quickly and a measuring method thereof.

It is another object of the present invention to incorporate a configuration for performing an approach / retreat operation of a probe with respect to a conventional ordinary scanning probe microscope for performing a fine measurement to measure a narrow area or a wide area. It is an object of the present invention to provide a scanning probe microscope and a measuring method thereof, which enable quick and precise fine measurement with high accuracy.

Still another object of the present invention is to prevent breakage, breakage and tip abrasion of a high aspect ratio probe used for measuring an uneven shape including a high aspect ratio contact hole or trench on a substrate surface. It is an object of the present invention to provide a scanning probe microscope and a measuring method therefor.

[0013]

Means for Solving the Problems A scanning probe microscope and a measuring method thereof according to the present invention are configured as follows to achieve the above object.

The scanning probe microscope according to the present invention is based on the premise that a probe facing the surface of a sample and a displacement detecting mechanism (optical lever type optical detection) for detecting a displacement of the probe with respect to the surface of the sample in the height direction. And a control means (servo control device) for controlling the distance between the sample and the probe based on a detection signal output by the displacement detection mechanism so as to be maintained at a preset reference distance. During measurement, the surface of the sample is scanned by the probe while maintaining the distance between the probe and the sample at a reference distance (for example, a pressed state), for example, for controlling the distance between the probe and the sample at the reference distance. It is configured to measure the uneven shape and the like of the sample surface using a voltage signal. The first scanning probe microscope according to the present invention further includes an approach / retreat drive device for approaching / retreating the probe to / from the surface of the sample, and the sample and the probe are controlled based on a servo control system by the control means. The approach / retreat driving device performs the approach / retreat operation of the probe at each of the plurality of sampling positions while continuing the control regarding the distance between the data, and acquires data at the sampling positions. The configuration and operation for the above-described measurement are applied to the usual ordinary narrow-area measurement, wide-area measurement, or measurement of the uneven shape of a sample having a high aspect ratio.

The above-mentioned scanning probe microscope preferably includes a moving mechanism for scanning the surface of the sample with the probe over a wide area. More preferably, the moving mechanism mounts the sample and moves the sample in a direction parallel to the sample surface.
This is a sample stage that is moved in units of m. Such a configuration is suitable for wide area measurement.

In the above-described scanning probe microscope according to the present invention, when a wide area measurement is performed by wide-area scanning of the mm class on the sample surface, a plurality of sampling positions are set as measurement points, and a search between the sampling positions is performed. In the movement of the needle, the probe moves while retracted from the sample surface, the probe is approached at the sampling position to perform the measurement, and during the measurement operation, control on the distance between the sample and the probe based on the servo control system Makes the wide area measurement practical. By continuing the servo control by the servo control system in this manner, the approach / retreat operation of the probe at the sampling position can be performed in a short time by using pulse driving.

In the scanning probe microscope having the above configuration, preferably, the probe is a probe having a high aspect ratio, and the probe measures a surface of a sample having a high aspect ratio. By using a probe with a high aspect ratio, it is possible to satisfactorily measure a sample surface having a high aspect ratio based on approach / retreat driving of the probe, not only in a wide area. As a probe with a high aspect ratio, for example, a diameter of 0.1 μm, a length of 1 μm, and a radius of a tip portion of 0.01 μm
It is an elongated probe.

The second scanning probe microscope according to the present invention has the above-described prerequisite, and further includes a moving mechanism for scanning the surface of the sample by the probe, and a moving mechanism for moving the probe in the height direction with respect to the surface of the sample. A piezoelectric element for displacing the probe, reference distance setting means for providing a voltage signal for determining the reference distance, approach / retreat signal supply means for supplying a voltage signal for causing the probe to approach / retreat to the surface of the sample, and a reference distance. Combining means (adder) for combining the voltage signal for determining the distance and the approaching / retreating voltage signal, and subtracting means (subtractor) for calculating the difference between the voltage signal output from the combining means and the detection signal and outputting a deviation signal And The control means generates a control voltage signal based on the deviation signal, and applies the voltage signal to the piezoelectric element to control the expansion and contraction operation. In this scanning probe microscope, similarly to the first scanning probe microscope described above, not only conventional narrow area measurement as in the past, but also wide area measurement, or high aspect ratio by using a probe with a high aspect ratio is used. It is applied to measurement of the uneven shape of a sample having

In the second scanning probe microscope described above, if a wide-area XY stage is used as the moving mechanism, the sample is moved with a large moving stroke of, for example, mm class, and the probe approaches the sample surface only at the sampling position. Then, the measurement operation is performed, and when the probe moves between the sampling positions, the probe is moved away from the sample surface. As a result, a wide range can be moved at high speed, measurement can be performed in a short time, and contact with the sample surface can be eliminated to reduce probe wear. In particular, the displacement of the probe in the height direction with respect to the sample surface, that is, the movement of approach / retreat, and the maintenance of the reference distance between the probe and the sample at the time of measurement, are controlled by a signal that sets the reference distance in the servo control loop. Approaching
By superimposing the evacuation signal, it is possible to perform the operation with a single piezoelectric element.

In the above configuration, preferably, the control means moves the probe toward and away from the surface of the sample at the sampling position where the measurement is performed, while continuing the servo control in the height direction for measurement. When moving from a certain sampling position to the next sampling position, control is performed so as to maintain the retracted state.

In the above configuration, the approach / retreat voltage signal output from the approach / retreat signal supply means is a pulse signal generated periodically.

In the above configuration, the moving mechanism is a sample stage on which the sample is mounted and which moves the sample in a direction parallel to the sample surface, for example, in the horizontal direction in units of mm.

In the above configuration, preferably, a displacement meter for detecting displacement due to expansion and contraction of the piezoelectric element is provided, and the surface irregularities of the sample are measured based on a signal output from the displacement meter.

A third scanning probe microscope according to the present invention has the above-described prerequisite configuration, and further includes a moving mechanism for scanning the surface of the sample with a probe over a wide area, and a sampling position for measuring. A piezoelectric element that matches the height position of the probe with respect to the surface of the sample to the reference distance based on the servo control system, and the probe is moved closer to the surface of the sample at the sampling position. An approach / retreat drive device for retreating from the surface of the sample, and a probe controlled by the approach / retreat drive device at each of a plurality of sampling positions while controlling the distance between the sample and the probe based on a servo control system. , And data is acquired at the sampling position. In this scanning probe microscope, similarly to the first scanning probe microscope described above, not only conventional narrow area measurement as in the past, but also wide area measurement, or high aspect ratio by using a probe with a high aspect ratio is used. It is applied to measurement of the uneven shape of a sample having

In the above configuration, preferably,
The retraction drive is a piezoelectric element. In addition, the moving mechanism,
When performing a wide-area measurement, it is preferable to use a sample stage on which a sample is mounted and the sample is moved in units of mm in a direction parallel to the sample surface. Further, a displacement meter for detecting displacement due to expansion and contraction of the piezoelectric element may be provided, and the surface unevenness of the sample may be measured based on a signal output from the displacement meter.

In the third scanning probe microscope described above,
When the probe approaches the sample surface and is held at a predetermined reference distance, a drive device for approaching / retreating operation is separately provided for the servo piezoelectric element that causes the probe to follow the sample surface. . The drive device performs approach / retreat at the sampling position, performs measurement in the approach state, and moves between the sampling positions in the retracted state.
At this time, the servo control of the servo piezoelectric element is always continued by the servo control system. When a piezoelectric element is used as the approach / retreat driving device, it can be simply configured in a two-stage configuration together with the servo piezoelectric element. In this scanning probe microscope, similarly to the first scanning probe microscope described above, not only conventional narrow area measurement as in the past, but also wide area measurement, or high aspect ratio by using a probe with a high aspect ratio is used. It is applied to measurement of the uneven shape of a sample having

A measuring method of a scanning probe microscope according to the present invention comprises a piezoelectric element for displacing a probe facing a surface of a sample in a height direction relative to the surface, and a displacement detecting mechanism for detecting a displacement of the probe in a height direction. And control means for controlling the distance between the sample and the probe to be maintained at the reference distance based on the detection signal output by the displacement detection mechanism, and maintaining the distance between the probe and the sample at the reference distance. This is a measurement method applied to a scanning probe microscope that measures the surface by scanning the surface with a probe while maintaining control over the distance between the sample and the probe based on the servo control system by the above control means. While approaching and retracting the probe at each of the multiple sampling positions,
This is a measurement method for acquiring data at a sampling position.

In the above-mentioned measuring method, preferably, a voltage signal for determining a reference distance is determined by a loop of a servo control system for maintaining a measuring state of the expansion / contraction operation of the piezoelectric element.
It can be configured to superimpose a voltage signal that causes the probe to approach / retreat from the surface of the sample. Preferably, the measuring method according to the present invention can be achieved by providing a drive and control mechanism for performing the approach / retreat operation of the probe as another independent mechanism not included in the servo control system.

The measuring method of the scanning probe microscope according to the present invention is a method for realizing the measuring operation of the scanning probe microscope having each of the above-described structures, and performs wide area measurement while approaching / evacuating at the sampling position. By keeping the control regarding the distance between the sample and the probe based on the servo control system, the approach / retreat operation of the probe can be instantaneously performed with simple control. According to the measuring method of the scanning probe microscope, not only conventional narrow-area measurement as usual, but also wide-area measurement or measurement of the uneven shape of a sample having a high aspect ratio by using a probe having a high aspect ratio Etc. can be performed.

[0030]

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

FIG. 1 shows a first embodiment of a scanning probe microscope according to the present invention, and shows the configuration of the entire system. In this embodiment, an example of an atomic force microscope will be described as a scanning probe microscope, and an example of wide-area measurement will be described. FIG. 2 shows a case where the atomic force microscope shown in FIG. 1 observes the surface of a sample while scanning it with a probe.
4 shows a timing chart related to a change in the position of a probe when measuring a wide range based on wide-area scanning. FIG. 2 shows the waveforms of the voltage signals of the respective parts when the probe is moved in each of the X and Z directions related to the control of the change in the position of the probe with respect to approach / retreat. The change (displacement) in the position of the probe is caused by the scanning operation of the probe in the substantially parallel direction (XY direction) along the sample surface and the height direction with respect to the sample surface for adjusting the distance between the sample and the probe. (Z direction). The X, Y, and Z directions are directions of three orthogonal axes X, Y, and Z, as shown in FIG.

As shown in FIG. 1, an XY scanner 12 is arranged on a table 11 held horizontally in the figure, and a sample 13 to be observed is arranged thereon. In FIG. 1, the plane parallel to the surface of the table 11 is a horizontal plane,
Here, an XY plane is defined by two orthogonal axes X and Y. The sample 13 is a thin plate-like member such as a semiconductor wafer, for example, and is arranged with the surface to be observed facing upward. The XY scanner 12 is a moving mechanism that moves the sample 13 in the X direction or the Y direction at a relatively large distance, and is, for example, a moving sample stage configured using a pulse motor or the like. The moving stroke in the XY direction by the XY scanner 12 is performed in units of mm (mm), and a stroke of, for example, several tens of mm is set.
For the sample 13 mounted on the XY scanner 12, a cantilever 15 having a probe 14 at its tip is disposed above the sample 13 to observe the upper surface. The tip of the probe 14 faces the surface of the sample 13. In the example shown in FIG. 1, the probe 14 is pressed against the sample surface, for example. A contact state or an arbitrary distance can be set between the probe 14 and the surface of the sample 13. According to the above configuration, by moving the sample 13 by the XY scanner 12, the probe 14 facing the sample 13 scans the sample surface over a wide range as a change in the relative positional relationship, and measures a wide area. It becomes possible.

The base end of the cantilever 15 is fixed, and the tip end provided with the probe 14 is a free end.
The cantilever 15 is an elastic lever member having a small spring constant. When an atomic force is generated between the tip 14 and the sample 13, the tip is displaced in the height direction with respect to the sample surface, and the tip is moved. Deflection occurs depending on the force received. 16
Is a Z-direction drive device that attaches the cantilever 15 to the lower end thereof and moves the cantilever 15 in a direction (Z direction) perpendicular to the horizontal plane. In this embodiment, the Z-direction driving device is formed of, for example, a single piezoelectric element. The piezoelectric element 16 is a servo piezoelectric element for maintaining the height position of the probe 14 with respect to the sample surface at a predetermined reference constant position based on servo control in the Z direction when performing normal measurement / observation. In addition, it is an approaching / retreating piezoelectric element for bringing the probe 14, that is, the cantilever 15, closer to or away from the surface of the sample 13. Thus, the single piezoelectric element 16 is used for servo and for approach / retreat. The piezoelectric element 16 is fixed to the microscope frame 10.

According to the above configuration, in a state where the probe 14 faces the surface of the sample 13 mounted on the XY scanner 12 with an interval, the sample 13 is relatively moved in the XY directions by the XY scanner 12. By adjusting the height position of the cantilever 15, that is, the probe tip 14 with respect to the sample surface by the expansion and contraction operation of the piezoelectric element 16 while moving with a large stroke, a wide-area observation based on a millimeter-class scanning range is performed on the sample surface. Becomes possible. The piezoelectric element 16 for adjusting the height position of the probe 14 with respect to the sample surface includes:
The probe 14 (cantilever 15) is placed on the sample surface at a predetermined interval (for example, a pressed contact state) at each of a number of sampling positions (measurement points) set at regular intervals in the measurement area on the sample surface by the approach / retreat operation. In the approaching state at each sampling position, it operates so as to follow the uneven shape of the sample surface based on servo control for normal measurement / observation. Thereby, measurement data of the sample surface is obtained at each sampling position. Acquisition of measurement data at the sampling position is performed at one point in the moving section in the approaching state. Preferably, the contact time can be shortened by retreating immediately after data acquisition. Therefore, when measuring the surface of the sample 13 by wide-area scanning, the probe 14 is approached only at the sampling position by the single piezoelectric element 16, and follows the surface to acquire measurement data on the unevenness of the sample surface. However, the movement of the probe 14 from one sampling position to the next another sampling position is performed in a state where the probe is separated from the sample surface by the retreat operation.

For the cantilever 15 disposed above the sample 13, a detection system for detecting the height position (displacement in the Z direction) of the probe 14 with respect to the sample surface is provided. In the case of the present embodiment, as an example, an optical lever type optical detection system configured by using the bending deformation of the cantilever 15 and a laser beam is used as the detection system. An optical lever type optical detection system includes a laser light source 22 that irradiates a laser light 21 to a reflection surface formed on the back surface of the cantilever;
It comprises at least a two-part photodetector 23 that receives the laser beam 21 reflected on the back surface. The laser light source 22 and the photodetector 23 are provided at the lower end of the piezoelectric element 16 so as to move with the movement of the piezoelectric element 16. The reflected spot of the laser beam 21 reflected on the back surface of the cantilever 15 is incident on the light receiving surface of the photodetector 23 divided into two. If the distance between the probe and the sample changes while the probe 14 receives an atomic force from the sample surface, the interatomic force received by the probe changes, the height position of the probe 14 is displaced, and the cantilever 15 The amount of deflection deformation changes. The reflected spot of the laser beam 21 on the light receiving surface of the photodetector 23 is displaced from its center position in accordance with the amount of change in the amount of flexural deformation of the cantilever 15, so that the distance between the probe and the sample is constant at a set reference. The probe 14 (the cantilever 1) with respect to the sample surface is held by the servo control system described later so as to be maintained at the distance.
The height position of 5) is adjusted. Thereby, the photodetector 2
The position of the reflected spot of the laser beam 21 on the light receiving surface of No. 3 is also maintained at the center position according to the set constant interval between the probe and the sample.

Next, the control system will be described. Reference numeral 30 denotes a servo control device for controlling the expansion / contraction operation of the servo piezoelectric element 16 in the Z direction. The servo controller 30 controls the distance between the probe and the sample (displacement of the probe) output from the photodetector 23.
Is input. Servo control device 30
Is a reference distance setting unit 31 that sets a reference constant distance and outputs a voltage signal s0 representing the constant distance, and an adder 32 that adds (combines) the signal s0 and the approach / retreat voltage signal s01. And the input detection signal s1
And a voltage signal s02 output from the adder 32, and a subtractor 33 for calculating and outputting a difference between the voltage signal s02 and a voltage signal s02 output from the adder 32. And a control circuit 34 for generating and outputting the voltage signal Vz. The approach / retreat voltage signal s01 is provided from the approach / retreat signal supplier 35 provided in the servo control device 30, and the signal content is a pulse signal output periodically. The voltage signal s02 output from the adder 32 is obtained by adding the voltage signal s0 for the reference distance and the voltage signal s01 for performing the approach / retreat operation. The control voltage signal Vz output from the control circuit 34 is applied to the piezoelectric element 16. The optical lever type optical detection system, the subtractor 33, the control circuit 34, and the piezoelectric element 16 form a feedback loop for servo control. By expanding and contracting the piezoelectric element 16 based on the servo control, the degree to which the atomic force acts between the probe and the sample on the sample 13 at each sampling position in the measurement area determined by the wide scanning range on the sample surface. The cantilever 15 is moved so that the probe approaches, and the distance between the probe and the sample is maintained at the reference distance so that the amount of flexural deformation of the cantilever 15 is constant, and the cantilever 15 is retracted between the sampling positions. To move. According to the above configuration, when the measurement is started,
The servo control system is always maintained in the active state, and the servo control regarding the expansion and contraction operation of the piezoelectric element 16 is continued at the time of movement between the sampling positions and at the time of measurement at the sampling position.

Reference numeral 40 denotes a higher-level control device, which is constituted by, for example, a personal computer. Control device 40
Is a signal processing device 41, a display device 42, an XY scanning circuit 4
3. It is composed of an input unit and the like. The signal processing device 41 includes a storage unit. The signal processing device 41 of the control device 40 is configured to receive the control voltage signal Vz applied to the piezoelectric element 16 from the control circuit 34 of the servo control device 30. Further, an X-Y scanning circuit 43 in the control device 40 is provided with an X-ray for mounting the sample 13 and scanning the same in the XY directions.
A scanning control signal s2 for controlling the operation of the Y scanner 12 is provided. The scanning control signal s2 for moving the sample 13 is output to the XY scanner 12, is given to the signal processing device 41, and is stored in the storage unit. The storage area of the signal processing device 41 stores the measurement area on the surface of the sample 13 as position data of the scanning range, and the measurement data (Vz) corresponding to each sampling position
Is stored. In the case of the present embodiment, by operating the XY scanner 12, wide area measurement by mm (millimeter) class wide area scanning can be performed. The signal processing device 41 of the control device 40 performs the above-described scan data (position data on the sampling position) on the measurement area and the voltage signal Vz applied to the piezoelectric element 16 at each sampling position.
By combining this with (the height data with respect to the surface of the sample 13), image data relating to the uneven shape of the observation surface of the sample 13 is created, and the observation image is displayed on the screen of the display device 42.

In the above configuration, the servo controller 30
Supplies a voltage signal Vz to the piezoelectric element 16 from the controller 4
When the measurement is started based on the application of the signal s2 to the XY scanner 12 from 0, the servo control system is always maintained in the active state, and the piezoelectric element is moved during the sampling position and when the measurement is performed at the sampling position. Servo control is continued for the expansion / contraction operation of 61. Here, “the servo control is continued” means that the servo control device 30 is maintained in the active state at least while the measurement is performed, and the amount of flexural deformation of the cantilever 15 (or the amount of displacement of the probe) is maintained.
Is detected by the optical lever type optical detection system including the laser light source 22 and the photodetector 23, and the distance between the probe 14 and the surface of the sample 13 is determined by a specific distance (reference distance setting) set at the time of measurement. (Reference distance set by the device 31). Approach / evacuation signal supplier 35
Is outputting the approach signal, a feedback voltage signal (Vz) is given to the piezoelectric element 16 and the probe 1
The distance between the sample 4 and the surface of the sample 13 is maintained at the specific distance. When the approach / evacuation signal supplier 35 is outputting the evacuation signal, the probe-sample distance is basically maintained at a specific distance based on the operation of the optical lever type optical detection system and the servo controller 30. However, since the evacuation signal is added, the piezoelectric element 16 is held in a contracted state that realizes a predetermined evacuation state based on the evacuation signal.

The measurement operation in a wide area based on the atomic force microscope having the above configuration will be described with reference to FIG. FIG.
(A) shows the approach and retreat operations of the piezoelectric element 16 to and from the sample 13, and (B) shows a timing chart. Note that the moving direction of the stage and the direction of the cantilever are not limited to those shown in the drawing, and the present invention is effective regardless of the arrangement.

According to the atomic force microscope, a wide area measurement can be performed on the surface of the sample 13 as described above. Although it is necessary to perform wide area scanning for wide area measurement, moving the sample 13 by the XY scanner 12 enables wide area scanning. Further, the probe 14 with respect to the surface of the sample 13
Is adjusted by the expansion and contraction operation of the piezoelectric element 16. As shown in FIG. 2A, as described above, the piezoelectric element 16 expands and contracts with the applied voltage Vz as described above, and at the sampling position, the piezoelectric element 16 becomes larger as indicated by the broken line by the approach / retreat signal s01. The probe 14 (the cantilever 15) is brought close to and pressed against the surface of the sample 13 (state a), and in this state, the surface of the sample is tracked according to the servo control system to measure the unevenness of the surface.
The retreat signal s01 causes the piezoelectric element 16 to largely contract as shown by the solid line, retreat the probe 14 from the surface of the sample 13 (state b), and move to the next sampling position. In FIG. 2A, the piezoelectric element 16 based on the approach / retreat signal is shown.
A range (separation / disconnection range) L caused by the expansion / contraction operation of is shown.

Further, the timing chart (B) of FIG. 2 shows an operation example in which measurement is performed at a certain sampling position P1, and then the measurement is moved to the next sampling position P2. In the timing chart (B), X included in the XY scanner 12
A signal s0 for setting the speed in the X direction by the scanner, a reference distance, a signal s01 for approaching / evacuating, a signal s0 and a signal s0.
1 shows the change of the sum of 1 and the change state of the voltage Vz.
In the timing chart, the horizontal axis shows the passage of time,
In FIG. 2, it corresponds to the X direction which is the moving direction. XY
The speed of the scanner 12 by the X scanner is maintained at a constant speed. Therefore, the sample 13 is always moving with respect to the probe 14.

A signal s0 for setting the distance between the probe and the sample when the probe 14 is brought close to the surface of the sample 13.
Is always kept at a preset value (voltage value V ₀ > 0). In the sense of the measurement by the atomic force microscope, according to the configuration of the measurement according to the present embodiment, the servo control is always kept in a state of being applied, and the servo control is continued. Since the signal s0 is set to a positive constant voltage, when the probe is actually brought close to the sample surface, the probe is pressed against the sample surface. Pressing force for pressing the probe on the sample surface is determined by the voltage value V ₀ which signal s0. The signal s0 for setting a fixed distance serving as a reference (pressing state in the present embodiment) is given by the reference distance setting unit 31 as described above.

At the sampling positions P1 and P2 where the measurement is performed, the approach / retreat voltage signal s01 output from the approach / retreat signal supplier 35 is 0, and the voltage signal s02 output from the adder 32 is s0. Therefore, at each sampling position, a surface measurement based on the following of the sample surface is performed as in the case of the conventional atomic force microscope. However, data relating to the unevenness information on the sample surface is actually acquired at one point in the section in the approaching state. After the measurement is completed at the sampling position P1, it moves to the next sampling position P2.
−V ₁ is output from the save signal supply unit 35. This voltage value is a negative voltage whose absolute value is greater than the voltage V ₀ . Accordingly, the adder 32 a voltage signal output from s02 (= s0 + s01) is -V ₂ (= V ₀ -V ₁
). As a result, the pressing force of the probe against the sample surface is set to a negative pressing force, that is, an attractive force. Since the servo control system is always effective as described above, when the pressing force becomes negative, the probe 14 is retracted from the sample surface. Actually, since the control cannot be performed to a negative force exceeding the surface tension, the probe is completely retracted, and the servo control system is maintained in this state. Therefore, the probe moves from the sampling position P1 to the next sampling position P2 while being away from the sample surface.

When the sampling position P2 is reached, the output of the approach / retreat signal supply unit 35 becomes 0 for a certain period, during which time,
The voltage signal s02 output from the adder 32 becomes V ₀ , the piezoelectric element 16 extends greatly, the probe 14 is pressed against the surface of the sample 13, and the measurement based on the surface following is performed.

As described above, the voltage signal s02 for determining the position of the probe 14 in the loop of the servo control system is different from the signal s0 representing the reference distance by the approach / retreat voltage signal s0.
Since a periodic pulse signal was generated as 1 and superimposed on it, the servo control was continued,
A wide area measurement can be performed while approaching / evacuating at each of a large number of sampling positions. That is, when performing surface observation in a specific measurement region on the surface of the sample 13,
Setting multiple sampling positions for measurement, approaching and retreating the probe to the sample surface at each sampling position to measure, and approaching and retracting the probe while servo control is continued. Was made possible. With this configuration, the wide area measurement described above is performed.
The above arrangement makes it possible, in particular, to perform wide-area measurements quickly and without damaging or damaging the probe or the sample.

The control voltage Vz applied to the piezoelectric element 16 is such that the probe 14 follows the sample surface by the continuous operation of the servo control system when the probe 14 approaches the surface of the sample 13 as described above. Since the expansion / contraction operation of the piezoelectric element 16 is controlled as shown in FIG. 2B, as shown in FIG. 2B, a signal 45 corresponding to the unevenness of the sample surface is superimposed on the pulsed voltage 44. Although the case where the speed by the X scanner is constant has been described, the present invention includes a case where acceleration / deceleration control is performed for movement between each sampling position, and a case where movement by step-and-repeat is performed for each sampling position. In the category.

In the above description of the first embodiment, an example of wide-area measurement using an atomic force microscope has been described. However, at the sampling position (measurement point) in the measurement area, the probe (cantilever) approaches and retreats from the sample surface to perform measurement, and moves to the next sampling position in a retracted state away from the sample surface. The measurement method for keeping the state of the servo control by the servo control device 30 continued is not limited to the wide area measurement. For example, the present invention can be applied to conventional narrow-range measurement. In the case of such a narrow area measurement, a narrow area moving mechanism is used as the XY scanner 12. In the case of the narrow area moving mechanism, for example, it is configured using a piezoelectric element.

The above-described measuring method is convenient when measuring an object having a high aspect ratio using a probe having a high aspect ratio. That is, with the miniaturization of devices and elements formed on a substrate in a recent semiconductor manufacturing process, holes (contact holes and the like) and grooves (trench and the like for element isolation) having a high aspect ratio (5 to 10) are formed. Since the measurement has to be performed, it is necessary to measure the uneven shape of the substrate surface using a long and thin probe having a high aspect ratio even in an atomic force microscope. In the measurement using a probe having such a high aspect ratio, according to the conventional measurement method of an atomic force microscope, problems such as breakage, breakage, and wear of the tip of the probe are likely to occur. On the other hand, if the measurement method according to the first embodiment is used, even if a probe having a high aspect ratio is used, it is possible to prevent the probe from being broken, broken, and worn at the tip.

In the above sense, the configuration and measuring method related to the atomic force microscope described in the above embodiment are not limited to wide-area measurement by wide-area scanning, but can be applied to measurement in which the measurement range is normal. it can.

Next, a second embodiment of the scanning probe microscope according to the present invention will be described with reference to FIG. In FIG. 3, elements substantially the same as the elements shown in FIG. 1 are given the same reference numerals, detailed description thereof will be omitted, and the description of the first embodiment will be cited for the description. It shall be.

In the second embodiment, as in the first embodiment, the probe is measured at each sampling position in the measurement area on the surface of the sample 13 while the servo control based on the servo controller 30 is continued. 3 shows a configuration for performing the approach / retreat operation. In addition to the wide area measurement, narrow area measurement and measurement of an object having a high aspect ratio can be performed.

The characteristic configuration of this embodiment is that the control voltage signal Vz output from the control circuit 34 is not used as the measurement data regarding the unevenness of the sample surface input to the signal processing device 41, The point is that a displacement meter 50 for detecting the displacement is separately attached to the element 16 and the displacement signal output from the displacement meter 50 is used. Various devices can be used as the displacement meter 50.
The displacement signal output from the displacement meter 50 is a signal processing device 41.
Is input to In the configuration of the first embodiment, the voltage Vz
Was used, it was necessary to extract the signal 45 for the unevenness of the sample surface from the voltage Vz. In the case of the present embodiment, the displacement meter 50 was used to directly output the signal for the unevenness of the sample surface. It becomes possible to take in. Other configurations, that is, approach / retreat operations at sampling positions in wide area scanning, and measurement operations, signal processing,
Creation and display of an image are substantially the same as those described in the first embodiment.

Next, a third embodiment of the scanning probe microscope according to the present invention will be described with reference to FIG. In this embodiment, the first piezoelectric element 51 is replaced with the second piezoelectric element 52
And a Z-direction driving device is constituted by a two-stage piezoelectric element structure. The piezoelectric element 51 corresponds to the piezoelectric element 16 for servo described above. However, in the case of the present embodiment, the piezoelectric element 51 is used only as a servo piezoelectric element for tracking a surface during measurement, and is not used as an approach / retreat piezoelectric element as in the above-described embodiment. The piezoelectric element 52 is used as a piezoelectric element dedicated to the approach / retreat operation. Thus, in the present embodiment, Z
The directional drive device is composed of a two-stage piezoelectric element, and the surface following operation for measurement and the approach / retreat operation at the sampling position are performed by separate piezoelectric elements. Piezoelectric element 5
As for the method of providing 1, 52, they can be prepared separately, or the electrode arrangement is devised for a single piezoelectric element, and the piezoelectric element for measurement operation and the piezoelectric element for approach / retreat are incorporated. It is also possible to do so. In FIG. 4, the same reference numerals are given to substantially the same elements as those described in the above-described embodiment.

Since the piezoelectric element 52 for approaching / retreating is separately prepared for the piezoelectric element 51 for following the surface of the measuring operation, the servo controller 30 uses the approaching / retreating signal supplier 35 shown in FIG. The adder 32 becomes unnecessary, and FIG.
They have been excluded. Servo control based on the servo control system including the servo control device 30 is continuously performed with respect to the expansion and contraction operation of the servo piezoelectric element 51 in the Z direction. Further, the operation of approaching and retracting the probe at the sampling position as described above is performed by the expansion and contraction operation of the piezoelectric element 52. The expansion / contraction operation for approach / retreat of the piezoelectric element 52 is performed by the approach / retreat signal s3. The approach / evacuation signal s3 is the approach / evacuation voltage signal s described above.
It is substantially the same as 01. Approach / evacuation signal s3
Can be provided from the above-described approach / retreat signal supply unit 35 separately provided, or can be provided from the signal processing device 41 of the higher-level control device 40.

FIG. 5 is a view corresponding to FIG. 2 described above.
A measurement operation in a wide area or the like based on the atomic force microscope according to the third embodiment will be described. In FIG. 5, (A) shows the operation state (a, b) of approach / retreat of the piezoelectric element 52 to / from the sample 13, and (B) shows a timing chart. This timing chart (B) shows an example of the measurement operation at the sampling positions P1 and P2 similar to the above-described embodiment. In the timing chart (B) of FIG. 5, the speed in the X direction by the X scanner included in the XY scanner 12,
Signal s0 for setting reference distance, signal s for approaching / evacuating
3, the distance between the probe and the sample, and the changing state of the voltage Vz are shown. In the timing chart, the horizontal axis corresponds to the X direction which is the moving direction. The speed in the X direction and the signal s0 are the same as those described in FIG. The approaching / evacuating signal s3 is a pulse signal (positive pulse voltage) 53 periodically generated corresponding to the sampling positions P1 and P2. The distance between the probe and the sample is determined by the positive pulse voltage 53
When a positive pulse voltage 53 is not generated, the value is 0 (section), and when the positive pulse voltage 53 is not generated, the retreat state is a predetermined distance away (section). Also, the servo piezoelectric element 51
Is applied to the sample surface (P1, P2), the probe approaches the sample surface and follows the sample surface in the section corresponding to the sampling position (P1, P2). Since the needle is moving away from the sample surface and moving away from the sample surface, the piezoelectric element 52 extends at the maximum stroke in order to make the distance between the probe and the sample the reference distance,
Vz is the maximum value. Sampling position P1, P
The servo value of Vz at one point in the section 2 is acquired as measurement data. The expansion / contraction operation of the piezoelectric element 52 for the approach / retreat operation can be performed at both ends of the maximum position and the minimum position in the drive range of the piezoelectric element 52, or can be performed between a fixed position and another fixed position in the drive range. 2
It can also be done between points.

According to the configuration of the third embodiment described above, the approaching / retreating piezoelectric element 52 provided separately from the servo piezoelectric element 51 for the measuring operation allows the probe 14 to be moved at the sampling position. Approach the surface of sample 13
It can be evacuated. With this configuration, it is possible to perform wide-area measurement by wide-area scanning while exhibiting the effects described in the above-described embodiment. Also in the third embodiment, in the control operation for measurement, the servo control system is always kept in the active state, and the servo control regarding the operation of the piezoelectric element 51 is continued. Further, similarly to the above-described embodiment, narrow-area measurement can be performed, and an object having a high aspect ratio can be quickly measured using a probe having a high aspect ratio.

In the above embodiment, the piezoelectric element is used as the approach / retreat actuator.
An actuator using a pulse motor, an actuator using hydraulic pressure, an actuator using pneumatic pressure, or the like can also be used. Also in the third embodiment, a configuration using a displacement meter can be adopted.

In each of the above embodiments, the XY scanner for moving the sample is provided as a moving mechanism for performing scanning. However, a moving mechanism may be provided for the probe. Although the atomic force microscope has been described as an example of the scanning probe microscope, the present invention can be applied to other types of scanning probe microscopes such as a tunnel microscope. Furthermore, in each of the above-described embodiments, the scanning probe microscope of the present invention has been described from the viewpoint of the configuration of the apparatus. However, it is needless to say that the present invention can be grasped as a measuring method by focusing on the operation method. is there.

[0059]

As apparent from the above description, the present invention has the following effects.

A plurality of sampling positions are set as measurement points in the measurement of the uneven shape and the like on the sample surface, and when the probe is moved between the sampling positions, the probe is moved away from the sample surface and is moved at the sampling position. Since the measurement is performed by bringing the needle closer, and the control of the distance between the sample and the probe based on the servo control system is continued during the measurement operation, the usual narrow area measurement, wide area measurement, Measurement of a sample surface with a high aspect ratio using a probe with a high ratio, etc. is performed while maintaining good conditions for driving the approach and retreat of the probe at each sampling position, without damaging the probe. It can be done smoothly and quickly.

Further, the wide-area measurement is made practical, and the approach and retreat operations of the probe at the sampling position can be instantaneously performed by simple operation control using pulse driving, and the time required for the approach operation is obtained. Can be shortened, so that the entire measurement time can be shortened. In addition, with this configuration, the unevenness information of the sample surface over a wide scanning range of mm class is measured with a resolution of sub-nm or less, the measurement time is reduced, the wear of the probe is reduced, and the measurement accuracy due to the wear of the probe is measured. Can be prevented from decreasing.

When the irregularities formed on the surface of the sample, such as a semiconductor substrate, are holes or grooves having a high aspect ratio, an elongated probe having a high aspect ratio is used. Since the approach and retreat operations of the probe can be performed while control is continued, the probe can be quickly approached and retracted without damaging the probe,
Measurement can be performed smoothly.

A moving mechanism capable of scanning the surface of the sample with the probe over a wide area is provided. A piezoelectric element for changing the height of the probe with respect to the surface of the sample is formed as a single unit.・ By superimposing the retracting signal, approach / retreat operation and measurement operation at each sampling position can be performed with a single piezoelectric element. It is possible to reduce the measurement time in wide area measurement, reduce the wear of the probe, and prevent the measurement accuracy from being lowered due to the wear of the probe.

Further, the above moving mechanism, a piezoelectric element for matching the height position of the probe with respect to the surface of the sample to the reference distance based on the servo control system at the sampling position for measurement, and the probe at the sampling position. An approach / retreat drive device such as a piezoelectric element that moves the probe away from the surface of the sample when moving between the sampling positions is provided, and the distance between the sample and the probe is controlled based on the servo control system. With the control being continued, the approach / retreat drive device approached / retracted the probe at each of the multiple sampling positions, and acquired data at the sampling positions, so that wide-area measurement could be performed with the same effect as described above, Wide-area measurement, high aspect ratio measurement, etc. can be performed simply by adding a configuration for performing approach / retreat operations to a conventional scanning probe microscope. Kill.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an overall system of a first embodiment of a scanning probe microscope according to the present invention.

FIG. 2 is a diagram illustrating an operation (a measuring method) of the scanning probe microscope according to the first embodiment.

FIG. 3 is a configuration diagram illustrating an entire system of a second embodiment of the scanning probe microscope according to the present invention.

FIG. 4 is a configuration diagram illustrating an entire system of a third embodiment of the scanning probe microscope according to the present invention.

FIG. 5 is a diagram illustrating an operation (a measuring method) of a scanning probe microscope according to a third embodiment.

FIG. 6 is a diagram for explaining the movement of a probe for performing a wide-area measurement in the approach / retreat operation.

[Explanation of symbols]

 Reference Signs List 12 XY scanner 13 Sample 14 Probe 15 Cantilever 16 Piezoelectric element 30 Servo controller 31 Reference distance setter 32 Adder 33 Subtractor 34 Control circuit 35 Approach / retreat signal supplier 40 Controller 51 Servo piezoelectric element 52 Approach / retreat Piezoelectric element

Claims (20)

[Claims] A probe facing a surface of a sample, a displacement detecting mechanism for detecting a displacement of the probe in a height direction with respect to the surface of the sample, and the sample based on a detection signal output by the displacement detecting mechanism. And control means for controlling the distance between the probe and the probe to be maintained at a reference distance, wherein the surface is maintained at the reference distance between the probe and the sample at each of a plurality of sampling positions. A scanning probe microscope for measuring the surface by scanning the probe with the probe, comprising: an approach / retreat drive device for approaching / retreating the probe with respect to the surface of the sample at the sampling position; Approach / retreat of the probe by the approach / retreat drive device at each of the plurality of sampling positions, while continuing to control the distance between the sample and the probe based on the servo control system by It performed, scanning probe microscope and obtaining the data at the sampling location. 2. The scanning probe microscope according to claim 1, further comprising a moving mechanism for scanning the surface of the sample by the probe in a wide area. 3. The scanning type according to claim 2, wherein the moving mechanism is a sample stage on which the sample is mounted, and the sample is moved by a length of mm in a direction parallel to the sample surface. Probe microscope. 4. The scanning probe microscope according to claim 1, wherein the probe is a probe having a high aspect ratio, and the probe measures a surface of the sample having a high aspect ratio. 5. A probe facing a surface of a sample, a displacement detecting mechanism for detecting a displacement of the probe in a height direction with respect to the surface of the sample, and the sample based on a detection signal output by the displacement detecting mechanism. And control means for controlling the distance between the probe and the probe to be maintained at a reference distance, wherein the surface is maintained at the reference distance between the probe and the sample at each of a plurality of sampling positions. A scanning mechanism for scanning the surface of the sample by the probe [in a wide area], and moving the probe to the surface of the sample. A piezoelectric element to be displaced in the height direction; reference distance setting means for providing a voltage signal for determining the reference distance; and providing a voltage signal for moving the probe toward and away from the surface of the sample at the sampling position. Approaching / evacuating signal supply means; synthesizing means for synthesizing the voltage signal for determining the reference distance and the approaching / evacuating voltage signal; calculating a difference between the voltage signal output from the synthesizing means and the detection signal; A subtraction unit that outputs a signal, wherein the control unit generates a control voltage signal based on the deviation signal, and applies the voltage signal to the piezoelectric element to control the expansion and contraction operation. A scanning probe microscope characterized by the following. 6. The scanning probe microscope according to claim 5, wherein the moving mechanism is a mechanism for performing the scanning of the sample surface by the probe in a wide area. 7. The scanning probe microscope according to claim 5, wherein the probe is a probe having a high aspect ratio, and the probe measures a surface of the sample having a high aspect ratio. 8. The control means moves the probe toward and away from the surface of the sample at the sampling position where the measurement is performed while continuing the servo control in the height direction for measurement. The scanning probe microscope according to any one of claims 5 to 7, wherein the scanning probe microscope is held in a retracted state when moving from a sampling position to a next sampling position. 9. The method according to claim 5, wherein the approach / retreat voltage signal output by the approach / retreat signal supply means is a pulse signal generated periodically. Scanning probe microscope. 10. The moving mechanism mounts the sample,
7. A sample stage for moving the sample by a length of mm in a direction parallel to the sample surface.
A scanning probe microscope as described. 11. The apparatus according to claim 6, further comprising a displacement meter for detecting a displacement due to expansion and contraction of the piezoelectric element, and measuring a surface unevenness of the sample based on a signal output from the displacement meter. The scanning probe microscope according to claim 1 or 2. 12. A probe facing a surface of a sample, a displacement detection mechanism for detecting a displacement of the probe in a height direction with respect to the surface of the sample, and the sample based on a detection signal output by the displacement detection mechanism. And control means for controlling the distance between the probe and the probe to be maintained at a reference distance, wherein the surface is maintained at the reference distance between the probe and the sample at each of a plurality of sampling positions. In the scanning probe microscope for measuring the surface by scanning with the probe, a moving mechanism for performing the scanning of the surface of the sample by the probe, and the sampling position with respect to the surface of the sample based on a servo control system A piezoelectric element that matches the position in the height direction of the probe with the reference distance; and bringing the probe close to the surface of the sample at the sampling position, and moving the probe between the sampling positions. Comprises an approach / retreat drive device for retreating the probe from the surface of the sample, while maintaining control on the distance between the sample and the probe based on the servo control system, a plurality of the sampling positions A scanning probe microscope, wherein the approach / retreat driving device performs approach / retreat of the probe and acquires data at the sampling position. 13. The scanning probe microscope according to claim 12, wherein the moving mechanism is a mechanism for scanning the surface of the sample by the probe in a wide area. 14. The scanning probe microscope according to claim 12, wherein the probe is a probe having a high aspect ratio, and the probe measures a surface of the sample having a high aspect ratio. 15. The scanning probe microscope according to claim 12, wherein the approach / retreat driving device is a piezoelectric element. 16. The moving mechanism mounts the sample,
2. A sample stage for moving the sample by a length of mm in a direction parallel to the sample surface.
3. The scanning probe microscope according to 3. 17. A device according to claim 12, further comprising a displacement meter for detecting a displacement caused by expansion and contraction of said piezoelectric element, and measuring surface irregularities of said sample based on a signal output from said displacement meter. The scanning probe microscope according to claim 1 or 2. 18. A piezoelectric element for displacing a probe facing a surface of a sample in a height direction with respect to the surface, a displacement detecting mechanism for detecting a displacement of the probe in a height direction, and an output from the displacement detecting mechanism. Control means for controlling the distance between the sample and the probe based on the detection signal so as to be maintained at a reference distance, and the reference between the probe and the sample at each of a plurality of sampling positions. In a measuring method of a scanning probe microscope for measuring the surface by scanning the surface with the probe while maintaining the distance, controlling a distance between the sample and the probe based on a servo control system by the control means. Measuring the scanning probe microscope, wherein the approach and retreat of the probe is performed at each of a plurality of sampling positions while acquiring the data at the sampling positions. . 19. A loop of a servo control system for maintaining a measurement state of the expansion and contraction operation of the piezoelectric element, wherein the probe approaches and retreats from the surface of the sample in response to a voltage signal that determines the reference distance. 19. The measuring method for a scanning probe microscope according to claim 18, wherein a voltage signal is superimposed. 20. The scanning device according to claim 18, wherein a drive and control mechanism for performing an approach / retreat operation of the probe is provided as another independent mechanism not included in the servo control system. Method of scanning probe microscope.