JP2002031589A - Scanning probe microscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute excellent scanning by correcting a macro Z-direction fluctuation portion caused by inclination or swell of a sample, a characteristic of a scanner or the like in a scanning probe microscope. SOLUTION: This scanning probe microscope equipped with a probe arranged oppositely to the sample, a Z-direction scanner driven in the Z-direction, an X, Y-direction scanner for scanning in the X, Y directions, and a measuring head for detecting displacement of the probe, is also equipped with a Z-direction correction means for correcting the macro Z-direction fluctuation portion from the reference height. A first configuration of the Z-direction correction means has correction data in the Z-direction relative to a position in the X, Y directions for compensating the Z-direction fluctuation portion, and corrects the driving quantity of the Z-direction scanner based on the correction data. A second configuration of the Z-direction correction means has a tilt stage capable of adjusting a tilt angle unidirectionally or bidirectionally against a reference plane of the scanning probe microscope between a sample stand and the sample, and corrects the inclination caused by the characteristic of the sample or the scanner by the tilt stage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a scanning probe microscope.

[0002]

2. Description of the Related Art Surface observation is performed for observing the surface of metals, semiconductors, ceramics, resins, and the like, measuring roughness, and observing thin films such as liquid crystals, polymers, and vapor-deposited films. As a device for inspecting a fine surface shape of a sample, for example, an atomic force microscope (AFM) for measuring an atomic force acting between a probe and a sample surface, and a tunnel current flowing between the probe and the sample surface are used. The tunnel microscope (STM) used is known. Atomic force microscope (AFM) is a probe
A cantilever that supports the probe and a displacement detection system that detects bending of the cantilever, detects an atomic force (attractive force or repulsive force) between the probe and the sample, and determines that the atomic force is constant. The shape of the sample surface is observed by controlling the distance between the probe and the surface of the sample so that the distance between the probe and the sample surface is controlled.

In a scanning probe microscope, two-dimensional scanning of a sample by movement in the XY directions and feedback control in the Z direction are performed between the sample and the probe using a scanner movable in the XY directions and the Z direction. The shape of the sample surface is measured by acquiring the height information of the sample. The scanning in the XY direction and the feedback control in the Z direction are performed by a minutely displaceable drive mechanism such as a piezo element provided on the sample side or the probe side. The normal movement range of this drive mechanism is, for example, about several tens of μm in the XY directions, and on the order of several μm in the Z direction. As an example of a scanner using a tube type piezo element, the maximum scanning range (X, Y directions) is 30 μm × 30 μm.
m and a maximum measurement range (Z direction) of 5 μm are known.

[0004]

The height of the sample in the Z direction includes a micro height representing the shape of the sample surface and a macro height based on the inclination, undulation of the sample, and the characteristics of the scanner. I have. The scanning probe microscope obtains the shape of the sample surface by measuring micro height information from the height in the Z direction of the sample. On the other hand, the macro height
This is a variation in the Z direction that hinders scanning by the scanning probe microscope. Since the measurement range of the scanning probe microscope in the Z direction is limited by the movement range of the scanner in the Z direction,
In order to scan the entire scanning range on the sample, the height difference of the sample surface is smaller than the movement amount of the scanner in the Z direction, and both the minimum height position and the maximum height position of the sample are the Z position of the scanner.
Must be within range of movement in direction.

[0005] Even when the height difference of the sample surface is smaller than the amount of movement of the scanner in the Z direction, the height position of the sample at the scanning start point is determined with respect to the minimum height position and the maximum height position of the sample. The scanning may be affected by the position or the position of the starting position of the scanner in the Z direction at the scanning start point with respect to the movement range of the scanner in the Z direction. FIG. 8 is a schematic diagram for explaining the effect on scanning due to the macro Z-direction variation.
The macro Z-direction variation of the sample due to the inclination of the sample, the undulation of the sample, the characteristics of the scanner, and the like are shown. In FIGS. 8A and 8B, it is assumed that the movement amount b in the Z direction is the same as the height difference a, and scanning is started from the middle point of the movement range of the scanner.

FIG. 8A shows a case where the sample is inclined. When the sample S1 having the inclined surface with the height difference a is scanned by the scanner with the movement amount b in the Z direction, a range where scanning cannot be performed may occur depending on the scanning start point. When the position of P1 (the midpoint position of the scanning range c) is set as the scanning start point,
The entire scanning range c can be scanned. On the other hand, P2, P
When the position 3 (end point position of the scanning range c) is set as the scanning start point, the scanning ranges c2 and c3 cannot be scanned because a2 and a3 in the Z direction are outside the moving range of the scanner.

FIG. 8B shows a case where the sample has undulation. Even when the sample S2 having the undulation of the height difference a is scanned by the scanner having the movement amount b in the Z direction, a range where scanning cannot be performed may occur depending on the scanning start point. When the position of Q1 (the middle point of the scanning range c) is set as the scanning start point, the entire scanning range c can be scanned. On the other hand, when the positions of Q2 and Q3 (the highest point position and the lowest point position of the undulation) are set as the scanning start points, a2 'and a2 in the Z direction are set.
3 'is outside the moving range of the scanner, so the scanning range c
2 ′, c3 ′ cannot be scanned.

[0008] Even a sample having no inclination or undulation may cause apparent inclination or undulation depending on the characteristics of the scanner. FIG. 8C shows a state in which scanning is performed in the X and Y directions by deforming the piezo element. In such scanning, when viewed from a probe fixed in the X and Y directions, the surface of the sample is shown in FIG.
It has the undulation as shown in (d). Also,
Depending on the deviation of the movement in the X and Y directions, a tilt is included. The macro Z-direction variation caused by such scanner characteristics is also described in FIG.
As in (b), the scanning range is limited.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned conventional problems and to perform a good scan by correcting a macro Z-direction variation caused by a tilt, undulation of a sample, characteristics of a scanner, and the like. .

[0010]

SUMMARY OF THE INVENTION According to the present invention, there is provided a Z-direction correcting means for correcting a macro-Z-direction variation from a reference height. Is corrected. The present invention relates to a scanning probe having a probe opposed to a sample, a Z-direction scanner driven in the Z direction, an X and Y direction scanner for scanning in the X and Y directions, and a measuring head for detecting displacement of the probe. The microscope includes a Z-direction correction unit that corrects a macro Z-direction variation from a reference height.

A first aspect of the Z-direction correction means comprises Z-direction correction data for positions in the X and Y directions for compensating for Z-direction fluctuations, and the driving amount of the Z-direction scanner is determined based on the correction data. Is corrected. The correction data can be formed based on, for example, a macro Z-direction variation of the sample or the scanner. For example, the correction data can be data having the same magnitude as the macro Z-direction variation and the sign inverted. Alternatively, a reference height may be determined, and a variation in the Z direction from the reference height may be used. The macro Z-direction variation can be obtained in advance by measuring means such as a scanning probe microscope. At this time, if the entire scanning range cannot be measured by one scan, the measurement can be performed by connecting the Z-direction variation obtained by dividing the entire scanning range into a plurality of regions. As the Z-direction scanner, a drive mechanism for Z-axis feedback normally provided in a scanning probe microscope or a drive mechanism for Z-axis macro correction can be used.

A second aspect of the Z-direction correcting means includes a sample stage for supporting a sample, a probe arranged to face the sample stage, a Z-direction scanner driven in the Z direction, and X, Y
A scanning probe microscope equipped with an X and Y direction scanner for scanning in a direction and a measuring head for detecting displacement of a probe, wherein an inclination angle of a scanning probe microscope with respect to a reference plane between a sample stage and a sample is determined. A tilt stage that can be adjusted in one direction or two directions is provided, and the tilt stage corrects tilt due to characteristics of a sample or a scanner. The tilt stage can adjust the tilt angle in one direction such as the X direction or the Y direction, or in two directions such as the X direction and the Y direction. By adjusting the tilt angle in two directions, it is possible to cope with an arbitrary tilt direction of the sample surface. The adjustment of the tilt angle by the tilt stage can be performed based on visual observation of the sample surface or measurement data obtained by scanning. Note that the tilt direction of the tilt stage does not necessarily need to be the X direction or the Y direction, and the two directions do not need to be perpendicular if they form a predetermined angle with each other.

The adjustment of the tilt angle is performed with respect to a reference plane provided in the scanning probe microscope, so that the Z direction fluctuation due to the tilt and undulation of the sample and the Z direction fluctuation due to the scanner characteristics are both controlled. Can respond.

According to the first aspect of the Z-direction correction means of the present invention, it is possible to correct tilt and undulation due to the characteristics of the sample and the Z-direction scanner, and to perform a good scan without limiting the scanning range. be able to. Further, according to the second aspect of the Z-direction correction means of the present invention, it is possible to correct the tilt due to the characteristics of the sample and the Z-direction scanner, and it is possible to perform satisfactory scanning without limiting the scanning range. .
Further, it is also possible to perform visual adjustment without preparing correction data in advance.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings. First, a first embodiment of the present invention will be described. FIG. 1 is a schematic block diagram for explaining a first embodiment of the present invention, and is a diagram illustrating a scanning atomic force microscope as an example. The scanning probe microscope 1 includes a probe 2, a cantilever 3 that supports the probe 2, a displacement measuring head 4 that detects bending of the cantilever 3, and a scanner 5 that scans the sample S in the X and Y directions and moves the sample S in the Z direction. Probe 2 and sample S
Is detected by the amount of deflection of the cantilever 3 to measure the surface shape of the sample S.

The displacement measuring head 4 includes a light source such as a laser oscillator (not shown), an optical system such as a mirror and a slit, and a photodetector 4a such as a photodiode. Laser light emitted from the laser oscillator and reflected by the cantilever 3 is shown. Is detected by the photodetector 4a, whereby the displacement of the cantilever 3 is detected. The detection signal is measured by the measurement / control means 7, and height data of the sample S can be obtained. Further, the scanner 5 includes an X- and Y-axis driving unit 5a and a Z-axis feedback driving unit 5b. The X and Y axis driving means 5a scans the sample S in the X and Y directions by being driven by a control signal from the measurement / control means 7. on the other hand,
The drive means 5b for Z-axis feedback performs feedback control in the Z direction by PI control by the feedback control means 6 having received the detection signal. The X- and Y-axis driving units 5a and the Z-axis feedback driving unit 5b can be constituted by, for example, piezo elements.

In the Z direction feedback control signal,
A micro-displacement amount and a macro-Z-direction fluctuation amount of the sample surface are included, and when the feedback control signal is directly input to the Z-axis feedback driving unit 5b and driven,
The amount of displacement in the Z direction by the scanner 5 is an amount obtained by adding a macro Z direction variation to a micro displacement. This addition amount may exceed the fluctuation range of the Z-axis feedback driving unit 5b, and in this case, it becomes difficult to perform good scanning.

The scanning probe microscope according to the present invention has a Z
It is provided with a direction correction data 8 and a configuration for compensating a macro Z-direction variation using the correction data. The Z-direction correction data 8 is data for correcting tilt and undulation due to the characteristics of the sample and the Z-direction scanner.
It is stored in a storage means or the like in association with the coordinate position. In the configuration for performing the compensation, the correction data corresponding to the X and Y coordinate positions being scanned is read, and the read correction data is input to the Z-axis feedback driving means 5b together with the feedback signal from the feedback control means 6.

By inputting the correction data 8 to the Z-axis feedback driving means 5b, the Z-direction position determined by the Z-axis feedback driving means 5b becomes a macro Z position.
Only the micro Z-axis direction component is obtained by subtracting the direction fluctuation. The Z-axis feedback driving unit 5b displaces the sample S by this micro Z-axis direction component, and maintains the distance between the probe 2 and the sample S at a predetermined distance. The detection signal can be obtained as the feedback amount in the Z direction.
Accordingly, the displacement in the Z-axis direction is only a micro Z-axis direction component, so that the displacement can be kept within the fluctuation range of the Z-axis feedback driving unit 5b, and good scanning can be performed.

FIG. 2 is a schematic block diagram for explaining another configuration example of the first embodiment of the present invention. The configuration example shown in FIG. 1 is configured to include a Z-axis feedback driving unit 5b as a Z-axis direction driving unit.
The configuration example shown in FIG. 2 includes a Z-axis macro correction driving unit 5c in addition to the Z-axis feedback driving unit 5b as a Z-axis direction driving unit.

In this configuration example, the Z-axis feedback driving means 5b is controlled by a control signal from the feedback control means 6, and the Z-axis macro correction driving means 5c is controlled by correction data 8. The Z-axis feedback driving unit 5b displaces an amount obtained by adding the micro displacement amount and the macro displacement amount, while the Z-axis macro correction driving unit 5c displaces in a direction to compensate for the macro displacement amount. by this,
The displacement amount of the scanner 5 in the Z-axis direction is only a micro displacement amount from which a macro displacement amount is subtracted. Accordingly, the displacement in the Z-axis direction is only a micro Z-axis direction component, so that the displacement can be kept within the fluctuation range of the Z-axis feedback driving unit 5b, and good scanning can be performed.

The driving means 5c for Z-axis macro correction may be constituted by a piezo element similar to the driving means 5b for Z-axis feedback, or an arbitrary driving mechanism such as an electrostatic driving element or a linear motor may be applied. Can be. By using a drive mechanism having a large displacement amount as the Z-axis macro correction drive unit 5c, it is possible to cope with a large Z-direction variation that cannot be driven by the piezo element.

3 and 4 are schematic diagrams for explaining the correction of the macro displacement amount by the correction data. FIG. 3 shows an example of correcting the inclination, and FIG. 4 shows an example of correcting the undulation.
FIG. 3A schematically shows the displacement amount of the sample surface obtained by adding the micro displacement amount and the tilt amount. On the other hand, FIG. 3B schematically shows the displacement amount of the inclination, which is measured in advance and stored as correction data for compensating the displacement amount. Using the correction data of FIG. 3B, FIG.
By subtracting the macro slope from the displacement obtained by adding the micro displacement and the macro slope of FIG.
It is possible to extract only the micro displacement amount as shown in FIG.

FIG. 4A schematically shows the displacement amount of the sample surface to which the micro displacement amount and the undulation are added. On the other hand, FIG. 4B schematically shows the displacement amount of the undulation, which is measured in advance and stored as correction data for compensating the displacement amount. By using the correction data of FIG. 4B and subtracting the macro undulation from the displacement obtained by adding the micro displacement and the macro undulation of FIG. 4A, FIG. Only the micro displacement as shown can be extracted.

Since the micro displacement shown in FIGS. 3C and 4C is within the range of movement of the scanner in the Z direction,
The entire scanning range can be scanned without narrowing the scanning range. It should be noted that the macro fluctuation amount is represented by the slope in FIG.
In the case of the form including the undulation, it can be handled similarly by the correction data. Further, in the above configuration example, the correction data is stored as compensation for the previously measured displacement amount. However, the displacement amount itself is stored, and this displacement amount is corrected when the scanner is driven in the Z-axis direction. It is also possible to adopt a configuration in which adjustment is performed.

The acquisition of the correction data 8 can be obtained, for example, by the configuration shown in FIG. In the configuration shown in FIG. 5, in a normal scanning probe microscope, a detection signal fed back from the detector 4 to the feedback control means 6 is passed through a low-pass filter 9 to extract low-frequency components as macro fluctuations, and to provide correction data. 8 is stored. In this data acquisition, when a macro variation is large and cannot be performed in one scan, the scan range is divided and data obtained by a plurality of scans is combined.

Next, a second embodiment of the present invention will be described. FIG. 6 is a schematic diagram for explaining the second embodiment of the present invention. In the second embodiment, a Z-direction correcting unit that corrects a macro Z-direction variation enables an inclination angle with respect to a scanning probe microscope to be adjusted in one direction or two directions between a sample stage and a sample. It is composed of a tilt stage. FIG. 6A shows a configuration example in which the tilt angle is adjusted in one direction. The tilt stage 10 can adjust the tilt angle of the support surface that supports the sample S by the adjusting screw 11.

FIG. 6B shows a configuration example in which the tilt angle is adjusted in two directions. The first tilt stage 10a and the second tilt stage 10b having different tilt directions are provided. , 11b adjust the inclination angle of the support surface that supports the sample S. 6 (a),
FIG. 6B shows a configuration example in which the side supporting the sample S is a scanner, but as shown in FIG. 6C, a configuration example in which the probe side is a scanner. FIG.
In each of the tilt stages (a), (b) and (c), the adjustment of the tilt angle can be performed based on measurement data obtained by visually observing or scanning the surface of the sample S.

FIG. 7 is a view for explaining tilt adjustment by a configuration example in which the tilt angle shown in FIG. 6B is adjusted in two directions. In FIG. 7A, the tilt stages 10a and 10b are arranged so as to overlap with a sample table (not shown) with respect to the sample S whose surface Su is tilted, and the adjusting screw 11 is set.
The respective inclination angles are adjusted by a and 11b. FIG. 7B shows a state after adjusting the inclination angle.
The inclination of the surface Su of the sample S with respect to the reference plane of the scanning probe microscope can be corrected.

Here, when a sample stage (not shown) is used as a reference plane, the inclination of the sample can be corrected. Further, when a position different from the scanner is used as the reference plane in the scanning probe microscope, it is possible to correct not only the inclination of the sample but also the inclination based on the scanner characteristics.

[0031]

As described above, according to the scanning probe microscope of the present invention, it is possible to perform a good scan by correcting the macro Z-direction variation due to the inclination and undulation of the sample and the characteristics of the scanner. it can.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram for explaining a first embodiment of the present invention.

FIG. 2 is a schematic block diagram for explaining another configuration example of the first embodiment of the present invention.

FIG. 3 is a schematic diagram illustrating correction of a macro displacement amount (inclination) by correction data.

FIG. 4 is a schematic diagram for explaining correction of a macro displacement amount (undulation) by correction data.

FIG. 5 is a schematic block diagram for explaining acquisition of correction data.

FIG. 6 is a schematic diagram for explaining a second embodiment of the present invention.

FIG. 7 is a diagram illustrating tilt adjustment by a configuration example in which a tilt angle is adjusted in two directions.

FIG. 8 is a schematic diagram for explaining an effect on scanning due to a macro Z-direction variation.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Scanning probe microscope, 2 ... Probe, 3 ... Cantilever, 4 ... Detector, 5 ... Scanner, 5a ... Drive means for X and Y correction, 5b ... Drive means for Z-axis feedback,
5c: Z-axis macro correction driving means, 6: feedback control means, 7: measurement / control means, 8: correction data, 9
... low-pass filter, 10, 10a, 10b ... tilt stage, 11, 11a, 11b ... adjustment screw, S ... sample, S
u: Sample surface.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2F069 AA54 AA60 DD08 DD12 DD22 EE11 EE22 FF01 GG04 GG06 GG07 GG15 GG35 GG39 GG52 GG56 GG62 HH04 JJ04 JJ19 JJ25 LL03 MM01 MM24 MM32 NN00 PP02 QQ05

Claims (2)

[Claims] 1. A scanning type comprising a probe opposed to a sample, a Z-direction scanner driven in the Z direction, an X and Y direction scanner for scanning in the X and Y directions, and a measuring head for detecting displacement of the probe. A probe microscope, comprising: a Z-direction correction unit configured to correct a macro Z-direction variation;
The Z-direction correction means includes X, Y for compensating the Z-direction variation.
A scanning probe microscope, wherein a driving amount of a Z-direction scanner is corrected based on Z-direction correction data for a position in a direction. 2. A sample table for supporting a sample, a probe arranged to face the sample table, a Z-direction scanner driven in the Z direction, an X and Y direction scanner for scanning in the X and Y directions, What is claimed is: 1. A scanning probe microscope comprising a measuring head for detecting a displacement, comprising: a Z-direction correction unit for correcting a macro Z-direction variation, wherein the Z-direction correction unit is provided between a sample stage and a sample. A scanning probe microscope, characterized in that it is a tilt stage that allows a tilt angle with respect to a reference plane of the probe microscope to be adjusted in one direction or two directions.