JPH0886792A - Scanning probe microscope - Google Patents

Abstract

PURPOSE: To provide a scanning probe microscope which is capable of high- accuracy measurements even if the relative positions of a cantilever displacement detecting mechanism and a cantilever are varied. CONSTITUTION: The displacement of a cantilever 2 when the cantilever 2 is moved in Z direction and brought close to a sample 7 is detected as the displacement of a light receiving position on a photodetector 6. Then a correction signal generating circuit 13 generates and outputs a voltage correction signal VH proportional to a control signal VP transmitted from a scanning circuit 12, and using the VH a positioning circuit 10 corrects a displacement signal VO transmitted from the photodetector 6, and outputs the corresponding corrected displacement signal VS to a control circuit 11. As the control circuit 11 adjusts the second amount of movement of a Z driving portion 3b so that the displacement of the cantilever 2 is held constant, the scanning circuit 12 adjusts the first amount of movement of XY driving portions 3a, 3a, thereby moving the probe 1 to a predetermined region for scanning.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microscope apparatus for measuring a physical quantity of a sample, and in particular, it utilizes the atomic force or magnetic force acting between the two when a probe is brought close to the sample surface. The present invention relates to a scanning probe microscope that obtains shape information, magnetic information, and the like.

[0002]

2. Description of the Related Art Conventional types of scanning probe microscopes for measuring physical quantities on a sample surface include, for example, an atomic force microscope (AFM) and a magnetic force microscope (MFM).

The atomic force microscope (AFM) obtains shape information of a sample by measuring an atomic force acting between the probe and the sample. That is, the probe provided on the cantilever and the sample are brought close to each other, and the deflection (displacement) of the cantilever due to the atomic force acting between them is measured, and the observation surface of the sample is kept so that the displacement is kept constant. While controlling the relative position of the probe and the sample in a direction perpendicular to the direction (hereinafter appropriately referred to as “Z direction”), the two are relatively observed in the observation plane direction (hereinafter appropriately referred to as “X direction or Y direction”, Alternatively, it is moved in the “XY direction”) to perform scanning.

The magnetic force microscope (MFM) obtains the magnetic distribution of a sample by measuring the magnetic force acting between the probe and the sample. That is, in the configuration of the atomic force microscope described above, the probe is made of a magnetic substance, the probe and the sample are brought close to each other, and the deflection (displacement) of the cantilever due to the magnetic force acting between them is measured. While controlling the relative position of the probe and the sample in the Z direction so as to be kept constant, both are relatively moved in the XY directions for scanning.

Known techniques relating to the above scanning probe microscope include, for example, the following. In the configuration of the atomic force microscope, this known technique holds the cantilever in the moving mechanism and moves the probe closer to the sample to displace the cantilever. Then, the surface information of the sample is obtained by scanning the cantilever in the XY directions while controlling the position of the cantilever in the Z direction so that the displacement is kept constant.

[0006] In this known technique, in the configuration of the atomic force microscope, the sample is held by a mechanism capable of minute movement in the XY direction and the Z direction (hereinafter appropriately referred to as "moving mechanism"). , Move the cantilever by moving the sample closer to the probe. Then, the surface information of the sample is obtained by scanning the sample in the XY directions while controlling the position of the sample in the Z direction so that this displacement is kept constant.

[0007]

However, the above-mentioned known techniques have the following problems. That is, in the known technique, the cantilever is moved in the X, Y, and Z directions when observing the sample surface, but at this time, the mechanism for detecting the displacement of the cantilever (hereinafter appropriately referred to as “displacement detection mechanism”) does not move. Therefore, there is a problem that the relative position between the cantilever and the displacement detection mechanism changes, which may cause an error in the measurement result. That is, as an example, consider the case of a so-called optical lever type atomic force microscope in which the reflected light of the laser light applied to the cantilever is received by the light receiving element, and the displacement of the cantilever is detected as the position change of the laser light on the light receiving element. . In this case, when the cantilever is moved by the moving mechanism, the laser light source and the light receiving element in the optical system including the laser light source, the cantilever that is the reflecting mirror, and the light receiving element are fixed and do not move. Only the position moves. Therefore, these relative positional relationships change, and even if there is no unevenness in the Z direction of the sample, the light receiving position of the laser beam on the light receiving element changes, so that the light receiving element moves in the Z direction on the sample. There is a case in which a detection result as if there is unevenness is output, and there is a disadvantage that a measurement error may occur in the displacement measurement and the measurement accuracy may decrease. Also, this error is difficult to correct after measurement. Also, this measurement error is caused by the cantilever X direction or Y
It increases as the amount of movement in the direction increases.

On the other hand, when the sample is moved in the X, Y and Z directions with respect to the probe as in the known technique, the positional relationship between the displacement detection mechanism of the cantilever and the cantilever does not change, and the problem of the known technique is However, when trying to observe a large sample, the scanning speed and control speed slow down due to its weight, and in order to avoid this, when observing a large sample, it is necessary to cut out only the part to be observed. There is another problem.

An object of the present invention is to provide a scanning probe microscope capable of performing highly accurate measurement even if the relative position between the cantilever displacement detecting mechanism and the cantilever changes.

[0010]

In order to achieve the above object, according to the present invention, a probe for detecting a physical quantity of a sample is attached, and the probe can be displaced in response to the physical quantity detected by the probe. A cantilever, a displacement amount detecting means for detecting a displacement amount of the cantilever and outputting a displacement amount signal corresponding to the cantilever, and a cantilever capable of moving the cantilever in a direction of an observation surface of the sample and a direction perpendicular to the observation surface. 1
And a second moving unit, a first moving amount control unit for controlling a first moving amount of the first moving unit so that the probe scans a predetermined region in the observation surface, and the displacement. Based on the second movement amount, second movement amount control means for controlling the second movement amount of the second movement means so that the displacement amount of the cantilever becomes constant according to the amount signal. In a scanning probe microscope apparatus provided with an arithmetic means for calculating information regarding the physical quantity of the sample and an output means for outputting and displaying the calculated information, the cantilever is moved when the cantilever is moved by the first moving means. Correction amount determining means for outputting as a correction signal according to a detection error unrelated to the physical quantity of the sample included in the displacement amount signal from the displacement amount detecting means, the displacement amount signal and the correction signal are input, and the correction signal By A scanning probe microscope apparatus further comprising: a correction calculation unit that corrects the displacement amount signal and outputs a corrected displacement amount signal corresponding to the corrected displacement amount to the second movement amount control unit. Will be provided.

Preferably, in the scanning probe microscope apparatus, the correction amount determining means is means for determining the correction amount of the correction signal according to the first movement amount of the first moving means. A featured scanning probe microscope apparatus is provided.

Further preferably, in the scanning probe microscope apparatus, the first moving means moves the cantilever in the observation surface direction in response to a control signal input from the first movement amount control means. The scanning probe microscope apparatus is characterized in that the correction amount determining means is a means for setting the correction amount of the correction signal to a voltage substantially proportional to the control signal.

More preferably, in the scanning probe microscope apparatus, the first moving means moves the cantilever in the observation surface direction in response to a control signal input from the first movement amount control means. Means,
The correction amount determining means stores the detection error of the displacement amount detecting means in advance in the form of correlation data between the control signal and the displacement amount of the cantilever detected by the displacement amount detecting means; Data output for reading the detection error corresponding to the control signal when the cantilever is moved in the direction of the observation surface from the correlation data stored in the data storage means and outputting this as a correction signal to the correction calculation means. And a scanning probe microscope apparatus.

Further preferably, in the scanning probe microscope apparatus, the first moving means moves the cantilever in the observation surface direction in response to a control signal inputted from the first movement amount control means. The correction amount determining means stores the detection error of the displacement amount detecting means in advance in the form of correlation data between the first movement amount and the displacement amount of the cantilever detected by the displacement amount detecting means. The data storage means to be stored and the detection error corresponding to the control signal when the cantilever is moved in the direction of the observation surface are read from the correlation data stored in the data storage means, and the correction error is used as the correction signal. There is provided a scanning probe microscope apparatus having a data output unit for outputting to a calculation unit.

More preferably, in the scanning probe microscope apparatus, the first and second moving means respectively move the cantilever according to a control signal inputted from the first and second moving amount control means. A scanning probe microscope apparatus is provided which is a piezoelectric element that moves in the direction of the observation surface and in a direction perpendicular to the observation surface.

Further, preferably, in the scanning probe microscope apparatus, the sample can be two-dimensionally moved in a plane substantially parallel to the observation surface, and the first moving amount by the first moving means is used. There is provided a scanning probe microscope apparatus characterized by further comprising a sample moving means that enables a large moving amount.

More preferably, in the scanning probe microscope apparatus, the displacement amount detecting means receives a laser light source and a condenser lens for irradiating the cantilever with a laser beam, and a reflected light of the laser beam by the cantilever. A light receiving element for outputting a light receiving position signal corresponding to the light receiving position as a displacement amount signal, and the correction calculating means receives the light receiving position signal and the correction signal and outputs the corrected displacement amount signal. There is provided a scanning probe microscope apparatus characterized by comprising a circuit.

Further preferably, in the scanning probe microscope apparatus, the displacement amount detecting means includes a metal probe and measures a tunnel current flowing between the metal probe and the cantilever to measure the displacement amount of the cantilever. There is provided a scanning probe microscope apparatus characterized by being a tunnel microscope for detecting.

[0019]

In the scanning probe microscope apparatus of the present invention,
When measuring the sample, the cantilever to which the probe for detecting the physical quantity of the sample is attached is moved in the Z direction perpendicular to the observation surface by the second moving means to bring the probe close to the sample. As a result, the cantilever is displaced in response to the physical amount detected by the probe, the displacement amount of this cantilever is detected by the displacement amount detecting means, and the corresponding displacement amount signal is output. The second movement amount control means controls the second movement amount of the second movement means so that the displacement amount of the cantilever becomes constant according to the displacement amount signal, and at the same time, the first movement amount control. The means controls the first movement amount of the first moving means that moves the cantilever in the direction of the observation surface of the sample to move / scan the probe to a predetermined area in the observation surface. During this scanning, a detection error unrelated to the physical quantity of the sample occurs due to the movement of the cantilever by the first moving means, and this detection error is included in the displacement amount signal output from the displacement amount detecting means. Therefore, the correction amount determining means outputs a correction signal corresponding to this detection error, and the displacement amount signal and the correction signal from the displacement amount detecting means are input to the correction calculating means, so that the correction displacement corresponding to the actual displacement amount of the cantilever. The amount signal is output to the second movement amount control means. That is, the influence of the detection error can be removed in real time during the measurement. Then, the information about the physical quantity of the sample is calculated by the calculating means based on the second movement amount in the scanning of the predetermined region performed based on the corrected displacement amount signal from which the detection error is removed, and the calculated information is The output is displayed by the output means.
Therefore, it is possible to finally obtain highly accurate information without error.

Further, in general, the above-mentioned detection error, that is, the detection error which occurs during scanning by the movement of the cantilever by the first moving means irrespective of the physical quantity of the sample, is the same as the first movement amount of the first moving means. It is considered that there is some correlation. For example, considering the case of the optical lever type atomic force microscope described above, the reflected light of the laser beam applied to the cantilever is received by the light receiving element, and the displacement of the cantilever is detected as the position change of the laser beam on the light receiving element. It is a composition. That is, in this case, since the cantilever alone is moved by the first moving means with respect to the fixed laser light source and light receiving element, the light receiving position of the laser light on the light receiving element changes, so that the first moving means A detection error will occur depending on the amount of movement. Therefore, by configuring the correction amount determining means to output the correction signal corresponding to the detection error according to the first movement amount of the first moving means, the detection error can be appropriately removed.

Further, when the first moving means is a means for moving the cantilever in the direction of the observation surface in accordance with the control signal input from the first movement amount control means, the above-mentioned detection error and the first The correlation with the amount of movement is the correlation between the detection error and the control signal. Therefore, by configuring the correction amount determining means so that the correction signal has a voltage substantially proportional to the control signal, the correction amount determining means can be adjusted to correspond to the magnitude of the detection error to be removed. Can be properly removed.

When the detection error and the control signal are correlated as described above, another configuration of the correction amount determining means is as follows.
Data storage means for storing in advance the detection error of the displacement amount detection means in the form of correlation data between the control signal and the detection error detected by the displacement amount detection means, and control when the cantilever is moved in the direction of the observation surface. There is also a configuration in which a detection error corresponding to a signal is read from the correlation data and output to the correction calculation means. in this case,
Before starting the measurement of the sample, first, the cantilever is moved by the first moving means without disposing the sample. At this time, since the surface information of the sample is not measured, the displacement amount of the cantilever apparently detected by the displacement amount detecting means is the magnitude of the detection error as it is, and the detection error at this time is associated with the control signal. The correlation data is stored in the data storage means. Then, the measurement of the sample is started, and the corresponding detection error is read from the data storage means by the data output means according to the value of the control signal at the time of scanning and is output to the correction calculation means. In the correction calculation means, the true cantilever displacement amount is calculated by subtracting the detection error input from the data output means from the apparent displacement signal of the cantilever including the error, and the corrected displacement amount signal corresponding to this is calculated. Output to the second movement amount control means. That is, this makes it possible to completely eliminate the error detected by the displacement amount detecting means.

Further, similarly, when the detection error and the first movement amount of the first moving means are correlated, as another configuration of the correction amount determining means, the detection error of the displacement amount detecting means is set to the first error.
Data storage means that is stored in advance in the form of correlation data between the amount of movement of the cantilever and the detection error detected by the displacement amount detection means, and the first when the cantilever is moved in the direction of the observation surface.
There is also a configuration in which a detection error corresponding to the movement amount of is read from the correlation data and is output to the correction calculation means. In this case, before starting the measurement of the sample,
First, the cantilever is moved by the first moving means without disposing the sample. At this time, since the surface information of the sample is not measured, the displacement amount of the cantilever apparently detected by the displacement amount detecting means is the magnitude of the detection error as it is, and the detection error at this time is referred to as the first movement amount. It is stored in the data storage means as correlated correlation data. Then, the measurement of the sample is started, and the corresponding detection error is read from the data storage means by the data output means in accordance with the value of the first movement amount during scanning and is output to the correction calculation means. In the correction calculation means, the true cantilever displacement amount is calculated by subtracting the detection error input from the data output means from the apparent displacement signal of the cantilever including the error, and the corrected displacement amount signal corresponding to this is calculated. Output to the second movement amount control means. That is, this makes it possible to completely eliminate the error detected by the displacement amount detecting means.

The first and second moving means move the cantilever in the direction of the observation surface and in the direction perpendicular to the observation surface in accordance with the control signals input from the first and second movement amount control means. By using the piezoelectric element, the cantilever can be finely moved in the direction of the observation plane and in the direction perpendicular to the observation plane, and the fine movement can be easily controlled.

Further, a sample moving means is provided which is capable of moving the sample two-dimensionally in a plane substantially parallel to the observation surface and which is capable of moving a larger amount than the first moving amount by the first moving means. By having this, it is possible to move the sample with this sample moving means after the measurement is completed, and in the next measurement, it is possible to set the scanning region at a position far away from the scanning region in this measurement, so that it can be easily performed in a wide range of the sample. Measurements can be made.

Further, the displacement amount detecting means receives a laser light source and a condenser lens for irradiating the cantilever with a laser beam, a reflected light of the laser beam by the cantilever, and a light receiving position signal corresponding to the light receiving position as a displacement amount signal. The light receiving element for outputting, and the correction calculating means comprises a light receiving position detecting circuit which receives the light receiving position signal and the correction signal and outputs a correction displacement amount signal, thereby detecting the displacement amount of the cantilever and responding thereto. It is possible to realize means for outputting the corrected displacement amount signal.

Further, the displacement amount detecting means is a tunnel microscope which includes a metal probe and measures the tunnel current flowing between the metal probe and the cantilever to detect the displacement amount of the cantilever. It is possible to realize a means for detecting the displacement amount of and detecting the displacement amount signal corresponding thereto.

[0028]

Embodiments of the present invention will be described below with reference to FIGS. A first embodiment of the present invention will be described with reference to FIGS. This example is an example of an atomic force microscope apparatus. The overall structure of the atomic force microscope apparatus according to this example is shown in FIG. In FIG. 1, the microscope apparatus 100 of the present embodiment.
Is a sample table 8 on which the sample 7 to be observed is placed.
And a cantilever 2 which is attached with a probe 1 for detecting a physical quantity (surface shape) of the sample 7 and which can be displaced in response to the detected shape, and a corresponding displacement amount signal V by detecting the displacement amount of the cantilever 2. A displacement amount detecting means for outputting _O , for example, a displacement amount detecting section 50 and three-dimensional X, Y, Z
First and second moving means for moving the cantilever 2 in any direction (described later), for example, the moving mechanism 3
And second movement amount control means for controlling the movement by the movement mechanism 3, for example, the control circuit 11 and the first movement amount control means, for example, the scanning circuit 12, the displacement amount detection unit 50, the control circuit 11, and the scanning. A display as an arithmetic means for controlling the circuits 12 collectively and for storing the measurement result and calculating the atomic force of the sample 7, for example, a control mechanism 14 and an output means for outputting and displaying the information on the sample 7 which is the measurement result. Part 15
And a correction amount determining means for correcting and calculating a detection error (described later) in the displacement amount detecting section 50 and outputting the correction signal V _H , for example, the correction signal generating circuit 13, the displacement amount signal V _O and the correction signal V _H.
Is input and a correction displacement amount signal V _S is output, for example, a position detecting circuit 10.

The moving mechanism 3 is a cylindrical piezoelectric element, and can be minutely deformed so that the cantilever 2 can be moved in the direction of the observation surface which is the upper surface of the sample 7 (for example, the horizontal direction, hereinafter appropriately referred to as the XY direction). Equipped with XY drive units 3a, 3a and a Z drive unit 3b that is capable of microscopic expansion and contraction so as to enable movement of the cantilever 2 in a direction that advances and retracts toward the sample 7 (for example, a vertical direction, hereinafter appropriately referred to as Z direction). ing.

The sample table 8 is installed so that the sample 7 faces the probe 1, and can be two-dimensionally moved within a plane substantially parallel to the observation surface of the sample 7 by a sample table moving mechanism (not shown). Is. The movable amount at this time is XY.
It is larger than the amount of movement in the XY directions by the drive units 3a, 3a. As a result, the sample 7 can be moved after the measurement is completed, and the scan area can be set at a position far from the scan area in the current measurement in the next measurement, so that the measurement can be easily performed in a wide range of the sample 7.

The scanning circuit 12 outputs a control signal to the XY drive sections 3a, 3a of the moving mechanism 3 so that the probe 1 scans a predetermined area on the observation surface of the sample 7. XY drive units 3a, 3
a is slightly deformed in response to this control signal, whereby
The cantilever 2 moves in the XY directions by a moving amount (hereinafter appropriately referred to as a first moving amount) according to the control signal.

The control circuit 11 controls the Z drive section 3 of the moving mechanism 3.
A control signal is output to b, and the Z drive unit 3b slightly expands and contracts in the Z direction in accordance with this control signal, whereby the cantilever 2 moves by the control signal (hereinafter referred to as the second movement amount as appropriate). ) Only moves in the Z direction. The control circuit 1
1 detects the second movement amount at this time.

The displacement amount detector 50 is composed of a laser light source 4, a condenser lens 5 for condensing the laser light from the laser light source 4 and irradiating the rear surface of the cantilever 2, and a photodiode. The reflected light is received, converted into a corresponding electric signal, and the displacement amount signal V of the cantilever 2 is received.
_The light receiving element 6 outputs as _O.

Although not shown in the drawing, the control mechanism 14 receives a second movement amount of the movement mechanism 3 detected by the control circuit 11 and stores the second movement amount, and a movement amount storage section for storing the movement amount. An arithmetic unit for calculating the surface shape information of the sample 4 based on the second movement amount stored in the amount storage unit and outputting it to the display unit 15. A scanning signal from the scanning circuit 12 is input to the control mechanism 14, and the above-described second movement amount is the scanning signal, that is, XY of the movement mechanism 3.
It is stored in association with the movement in the direction.

The correction signal generation circuit 13 divides the control signal V _P output from the scanning circuit 12 to the XY drive units 3a, 3a, that is, the correction signal V _H having a voltage substantially proportional to the control signal V _P. It is generated and output to the position detection circuit 10.
At this time, the position detection circuit 10 corrects the displacement amount signal V _O from the light receiving element 6 with this correction signal V _H , and outputs the corrected displacement amount signal V _S corresponding to this corrected signal to the control circuit 11.

Next, the operation of the above configuration will be described.
In the microscope apparatus 100 of this embodiment, when measuring the sample 7, the cantilever 2 to which the probe 1 is attached is attached.
Is moved in the Z direction by the action of the Z drive unit 3b of the moving mechanism 3 to bring the probe 1 closer to the sample 7. Probe 1 and sample 7
When and approach 1 nm, a minute atomic force acts between them to cause the cantilever 2 to bend, and the displacement amount of this cantilever 2 is detected as the displacement of the light receiving position on the light receiving element 6, and the displacement amount signal V _O Is output as. This displacement amount signal V _O is input to the control circuit 11 via the position detection circuit 10, and the control circuit 11 makes the second movement of the Z drive unit 3b of the movement mechanism 3 so that the displacement amount of the cantilever 2 becomes constant. While adjusting the amount, the scanning circuit 12 adjusts the first movement amount of the XY drive portions 3a, 3a of the moving mechanism 3 for moving the cantilever 2 in the XY directions to move the probe 1 to a predetermined area in the observation plane. Move / scan.

During this scanning, the XY drive units 3a, 3
When the cantilever 2 is moved in the XY directions by a, a detection error unrelated to the physical quantity (surface shape) of the sample 7 occurs,
The displacement amount detection unit 50 detects the displacement amount signal V _O of the cantilever 2 in a form included in the displacement amount signal V _O. This is shown in FIG.
An explanation will be given using (b).

In FIG. 2A, first, the probe 1 and the cantilever 2 are at the right side positions shown by the broken lines, and the laser light emitted from the laser light source 4 through the condenser lens 5 is the cantilever 2. The light is reflected at a point a on the back surface of, and is received at the position A of the light receiving element 6.

After that, assuming that the probe 1 and the cantilever 2 are moved to the left side in the figure by the distance x by the XY drive units 3a, 3a to reach the position shown by the solid line, from the laser light source 4 via the condenser lens 5. The irradiated laser light is
The light is reflected at a point b on the back surface of the cantilever 2 and is received at the position B of the light receiving element 6. That is, at this time, regardless of the surface shape of the sample 7, the light receiving position of the laser light on the light receiving element 6 changes by Δx in the following formula (*). Δx = x · tan θ · sin φ (*) where θ is the angle between the moving direction (horizontal direction) of the probe 1 and the cantilever 2 and the cantilever 2, and φ is the incident laser beam on the back surface of the cantilever 2. Is the angle formed by the reflected light.

Therefore, if no correction is applied to the state in which the detection error is generated as described above, the light receiving element 6 is apparently shown in FIG. 2 even if there is no surface irregularity in the Z direction of the sample 7. Cantilever 2 as shown by the solid line in (b)
Since the same state as the bent state is detected, a signal as if the sample 7 has a convex portion of height Δz is output to the position detection circuit 10. If the position detection circuit 10 is not provided, the displacement amount signal V _O is output to the control circuit 11 as it is, the control circuit 11 controls the moving mechanism 3 based on the displacement amount signal V _O , and the cantilever 2 is operated.
In the direction of the sample 7 (downward in the figure) by Δx.

In order to prevent this, the microscope apparatus 100 of the present embodiment is provided with the correction signal generation circuit 13, and the correction signal generation circuit 13 generates the correction signal V _H for correcting this detection error to detect the position. A displacement amount signal V _O of the cantilever 2 output to the circuit 10 and detected by the displacement amount detecting section 50.
Is corrected using this correction signal V _H , and this corrected correction displacement amount signal V _S is output to the control circuit 11. The determination of the correction amount in this detection error correction will be specifically described with reference to FIGS. As described above, the displacement amount detector 5
The detection error at 0, that is, the detection error caused by the movement of the cantilever 2 in the X and Y directions during scanning is the light receiving position on the light receiving element 6 when only the cantilever 2 is moved with respect to the fixed laser light source 4 and light receiving element 6. Is caused by a change in the XY driving unit 3a, 3a, it is considered that there is some correlation between the first movement amount of the cantilever 2 by the XY drive units 3a, 3a and the detection error. At this time, since the first movement amount corresponds to the control signal from the control circuit 11, as a result, the control signal and the detection error have a correlation.

Specifically, the detection error is represented by the output signal V _O output from the light receiving element 6 which is a photodiode, as shown in FIG. That is, the light-receiving element 6 is specifically composed of a photodiode divided into two, and the reflected light from the back surface of the cantilever 2 is incident on the light-receiving surface of the light-receiving element 6 substantially at the center, and the light is equally received by the two-divided diode. If so, the outputs from these two diodes become equal, and finally the value of the output signal V _O from the light receiving element 6 becomes zero as shown by the broken line. In this case, no detection error occurs. The control by the control circuit 11 so that the displacement amount of the cantilever 2 becomes constant is such that the light receiving position of the laser light on the light receiving element 6 is always at the center of the light receiving surface, that is, the light is evenly received by the two-divided diodes. To control it.

However, when only the cantilever 2 is moved in the XY directions and the light receiving position is changed as described above, and the incident amount of reflected light is large in one of the two split diodes and small in the other, the output signal V from the light receiving element 6 is detected. The value of _O does not become zero but takes a certain value as shown by the solid line in FIG. At this time, the value of the output signal V _O and the control signal V _P have a relationship as shown in FIG. 3A, for example, and V _O increases as V _P increases.

Here, in the correction signal generation circuit 13 of the microscope apparatus 100 of the present embodiment, this control signal V _P is divided to generate the correction signal V _H having a voltage substantially proportional to V _P. This is shown in FIG. In FIG. 3B, V
Relationship _H = k × V _P: in (k proportional constant). The value of k at this time is such that the magnitude of the correction signal V _H corresponds to the magnitude of the output signal V _O corresponding to the detection error to be removed (that is, the solid line in FIG. 3A and FIG. The straight line of b) is set as closely as possible), and the amount of voltage division from the control signal output from the scanning circuit 12 is determined by this. Then, the correction signal V _H for which the magnitude of the correction amount is determined in this way is output to the position detection circuit 10, and in the position detection circuit 10, from the output signal V _O having the characteristic shown in FIG. The calculation for reducing the correction signal V _H having the characteristic as shown in 3 (b) is performed. As a result, the detection signal V _S after this calculation, that is, after correction, is as shown in FIG. That is, the influence of the detection error can be appropriately removed, and the characteristics shown by the broken line in FIG. 3A can be approximated to the characteristics when the detection error does not occur.

As described above, the position detection circuit 10 removes the detection error contained in the displacement amount signal V _O based on the correction signal V _H from the correction signal generation circuit 13, and the corrected detection signal, that is, the corrected displacement amount. The signal V _S is output to the control circuit 11,
The control circuit 11 controls the moving mechanism 3 to measure the sample 7, and the second moving amount at this time is stored in the moving amount storage unit of the control mechanism 14.

Further, based on the set of the second movement amounts stored in the movement amount storage section of the control mechanism 14 in the scanning of the predetermined area of the sample 7 performed as described above, the control mechanism 1
Information regarding the surface irregularity shape of the sample 7 is calculated by the calculation unit in 4, and the calculated information is output and displayed on the display unit 15. Therefore, it is possible to finally obtain highly accurate information without error.

As described above, according to the microscope apparatus 100 of this embodiment, the correction signal generating circuit 13 generates the correction signal V _H for correcting the detection error so as to be a voltage substantially proportional to the control signal V _P. Then, the correction signal V _H is input to the position detection circuit 10, and the position detection circuit 10 performs correction by subtracting the correction signal V _H from the displacement amount signal V _O from the light receiving element 6, and the corrected displacement amount after the correction. Since the signal V _S is output to the control circuit 11, the influence of the detection error can be removed in real time during the measurement. Therefore, even if the relative positional relationship between the displacement amount detection unit 50 and the cantilever 2 is deviated, it is possible to finally obtain highly accurate surface shape information with no error. Further, at this time, it is not necessary to cut a large sample to make it smaller, unlike the conventional technique of moving the sample.

Although only the error due to the movement of the cantilever 2 in the XY directions was considered as the detection error in the above embodiment, the error due to the movement in the Z direction is problematic because the movement amount during measurement is extremely small. It can be considered that such an error does not occur.

A second embodiment of the present invention will be described with reference to FIGS. The present embodiment is an embodiment in which the configuration of the correction amount determining means is different. Atomic force microscope apparatus 2 according to the present embodiment
The overall configuration of 00 is shown in FIG. In FIG. 4, the configuration of the microscope apparatus 200 of the present embodiment is different from that of the microscope apparatus 100 of the first embodiment in that the detection error is as a correction signal unit that generates a signal for correcting the detection error in the displacement amount detection unit 50. Is stored in advance in the form of correlation data between the control signal V _P1 output from the scanning circuit 12 and the displacement amount signal V _O1 from the light receiving element 6, and the cantilever 2 moves in the XY directions after the start of measurement. And a data output unit 213a that outputs a signal V _O1 indicating a detection error, which corresponds to the control signal V _P2 when moving to the read position, to the read position detection circuit 10 from the correlation data stored in the data storage unit 213b. That is, the correction signal generation circuit 213 is provided. The other structure is almost the same as that of the first embodiment.

In the above structure, first, before the measurement of the sample 7 is started, the cantilever 2 is moved in the XY directions by the moving mechanism 3 without disposing the sample 7 on the sample table 8. Since this time the surface information of the sample 7 is not measured, the output signal V _O1 from the light receiving element 6 to be detected apparently in the position detection circuit 10 has a size of as detecting errors, the V _O1 at this time The value is stored in the data storage unit 213b as correlation data in which the value is associated with the control signal V _P1 . An example of this correlation data is shown in FIG.

After that, the sample 7 is placed on the sample table 8 to start the measurement, and the corresponding V _O1 is momentarily set by the data output unit 213a according to the value of the control signal V _P2 at the time of scanning.
It is read from 13b and output to the position detection circuit 10. The position detection circuit 10 subtracts the output signal V _O1 corresponding to the error input from the data output unit 213a from the output signal V _O2 from the light receiving element 6 including the detection error detected at this time. Output signal V _O of As described above, since the output signal V _O1 detected in advance is equal to the detection error, the detection error included in V _O is 0 regardless of the control signal V _P2 as shown in FIG. 5B. A displacement amount signal corresponding to this is output to the control circuit 11.

According to this embodiment, the position detection circuit 10 can completely eliminate the influence of the detection error.

In the above embodiment, the data storage unit 213b stores the detection error in the form of correlation data between the control signal V _P output from the scanning circuit 12 and the output signal V _O from the light receiving element 6. However, other forms of correlation data are possible. This modification will be described with reference to FIG. In FIG.
The configuration of the microscope apparatus 300 of this embodiment is different from that of the microscope apparatus 200 of the second embodiment in that the detection error in the displacement amount detection unit 50 is detected by the scanning circuit as the correction signal means for generating a signal for correcting the detection error. Moving mechanism 3 detected by 12
The first movement amount d _{1 in} the XY direction and the displacement amount detection unit 5
The data storage unit 313b, which is stored in advance in the form of correlation data with the output signal V _O1 from the light receiving element 6 indicating the detection error detected at 0, and the cantilever 2 is XY after the measurement is started.
And a data output unit 313a that outputs a signal V _O1 indicating a detection error corresponding to the first movement amount d ₂ when moving in the direction to the read position detection circuit 10 from the correlation data stored in the data storage unit 313b. That is, the correction signal generating circuit 313 having the above is provided. Other configurations are the second
This is almost the same as the embodiment described above.

The operation and action relating to the correction in this modification is the first movement of the moving mechanism 3 in which the control voltages V _P1 and V _P2 from the scanning circuit 12 in the second embodiment are detected by the scanning circuit 12. Since only the amount d is replaced, detailed description will be omitted. According to this modification, the same effect as that of the second embodiment can be obtained.

In the first and second embodiments described above, a so-called optical lever type structure is shown as an example of the structure of the displacement amount detecting section 50. However, the displacement amount detecting for detecting the displacement of the cantilever 2 is described. It can be applied even when a tunnel microscope is used as the section. This modification will be described with reference to FIG. In FIG. 7, a voltage is applied between the probe 1 and the metal probe 16 of the tunnel microscope by a voltage applying means (not shown). When the probe 1 and the metal probe 16 approach each other to some extent, a tunnel current flows between them, and the value of this tunnel current is measured by a measuring means (not shown). The distance between the probe 1 and the metal probe 16, that is, the amount of displacement of the probe 1 is detected based on the magnitude of the measured current value.

Also in this case, when the probe 1 and the cantilever 2 are moved leftward by x and moved from the broken line position to the solid line position, referring to FIGS. 2 (a) and 2 (b) in the first embodiment. The same problem as described occurs. That is, Z of sample 7
Even if there is no surface irregularity in the direction, the metal probe 16
Will output a detection result as if the sample 7 had a convex portion of Δx, and as a result, the cantilever 2
Is controlled to approach the sample 7 direction (downward in the figure) by Δx.

Therefore, by applying the correction method in the first and second embodiments, the same effect can be obtained in this modification.

In the first and second embodiments described above, a cylindrical piezoelectric element is used as the moving mechanism 3 for moving the cantilever 2, but any other typified by a tripod can be used. It can also be realized by using a moving mechanism having a different configuration, and the same effect can be obtained in this case as well.

Further, in the above-mentioned first and second embodiments, the atomic force microscope apparatus is taken up as an example of the scanning probe microscope apparatus. However, for example, the magnetic force microscope apparatus is almost the same as the atomic force microscope apparatus. It has a similar configuration,
Since the above-mentioned problems apply as they are, the first and second configurations can be applied to these scanning probe microscope apparatuses, and the same effect can be obtained in this case as well.

[0060]

According to the present invention, a correction signal for correcting a detection error is determined by the correction amount determining means, the correction signal is input to the correction calculating means, and the displacement of the cantilever detected by the displacement amount detecting means. Since the amount signal is corrected and the corrected displacement amount signal corresponding to this corrected displacement amount is output from the correction calculation means to the second movement amount control means, the influence of the detection error can be eliminated in real time during measurement. You can Therefore, even if the relative positional relationship between the displacement amount detecting means and the cantilever is deviated, it is possible to finally obtain highly accurate information with no error. Further, at this time, it is not necessary to cut a large sample to make it smaller, unlike the conventional technique of moving the sample.

Further, since the correction amount determining means is configured to determine the correction amount of the correction signal according to the first movement amount of the first moving means, a signal for appropriately removing the detection error is generated. be able to. Further, since the correction amount determining means is configured so that the correction signal has a voltage substantially proportional to the control signal, the voltage of the correction signal can be adjusted to correspond to the magnitude of the detection error to be removed. It is possible to appropriately remove the detection error in the correction calculation means to which is input. Further, the correction amount determining means stores in advance the detection error of the displacement amount detecting means in the form of a control signal or correlation data between the first movement amount and the detection error detected by the displacement amount detecting means. And the data output means for reading out the control signal when the cantilever is moved in the direction of the observation surface or the detection error corresponding to the first movement amount from the correlation data and outputting it to the correction calculation means. The detection means calculates the true cantilever displacement amount by subtracting the cantilever displacement amount corresponding to the error input from the data output device from the apparent cantilever displacement amount including the error detected by itself. The error can be completely eliminated.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing an overall configuration of an atomic force microscope device according to a first embodiment of the present invention.

FIG. 2 is a diagram for explaining a detection error that occurs in the displacement amount detection unit shown in FIG.

FIG. 3 is a diagram for explaining determination of a correction amount in correction of a detection error performed by the microscope apparatus shown in FIG.

FIG. 4 is a conceptual diagram showing an overall configuration of an atomic force microscope device according to a second embodiment of the present invention.

5A and 5B are diagrams for explaining a detection error correction operation performed by the microscope apparatus shown in FIG.

FIG. 6 is a conceptual diagram showing an overall configuration of an atomic force microscope apparatus according to a modified example of the second embodiment of the present invention.

FIG. 7 is a diagram showing a displacement amount detection unit of an atomic force microscope apparatus according to modified examples of the first and second embodiments of the present invention.

[Explanation of symbols]

 1 probe 2 cantilever 3 moving mechanism 3a XY drive section (first moving means) 3b Z drive section (second moving means) 6 light receiving element 7 sample 8 sample stage 10 position detection circuit (correction calculation means) 11 control circuit (Second movement amount control means) 12 Scanning circuit (first movement amount control means) 13 Correction signal generation circuit (correction amount determination means) 14 Control mechanism (calculation means) 15 Display unit (output means) 50 Displacement amount detection Part 100 Microscope device 200 Microscope device 213 Correction signal generation circuit 213a Data output part 213b Data storage part 300 Microscope device 313 Correction signal generation circuit (correction amount determination means) 313a Data output part 313b Data storage part

Claims (9)

[Claims] 1. A cantilever which is attached with a probe for detecting a physical quantity of a sample and is displaceable in response to the physical quantity detected by the probe, and a displacement amount signal corresponding to the detected cantilever displacement amount. A displacement amount detecting means for outputting the cantilever, first and second moving means capable of moving the cantilever in the observation surface direction of the sample and in a direction perpendicular to the observation surface, respectively, and the probe in the observation surface. A first movement amount control means for controlling a first movement amount of the first movement means so as to scan a predetermined area; and the displacement amount of the cantilever according to the displacement amount signal so that the displacement amount becomes constant. Second movement amount control means for controlling the second movement amount of the second movement means, calculation means for calculating information on the physical quantity of the sample based on the second movement amount, and the calculated information Output to display In the scanning probe microscope apparatus including means, a detection error unrelated to the physical quantity of the sample included in the displacement amount signal from the displacement amount detecting means when the cantilever is moved by the first moving means is detected. Accordingly, a correction amount determining means for outputting a correction signal, the displacement amount signal and the correction signal are input, the displacement amount signal is corrected by the correction signal, and the corrected displacement amount signal corresponding to the corrected displacement amount. To the second movement amount control means, and a correction calculation means for outputting the second movement amount control means to the scanning probe microscope apparatus. 2. The scanning probe microscope apparatus according to claim 1, wherein the correction amount determining means is means for determining a correction amount of the correction signal according to a first movement amount of the first moving means. A scanning probe microscope apparatus characterized by being present. 3. The scanning probe microscope apparatus according to claim 1, wherein the first moving unit moves the cantilever in the observation surface direction according to a control signal input from the first moving amount control unit. The scanning probe microscope apparatus is a means for moving, and the correction amount determining means is a means for setting the correction amount of the correction signal to a voltage substantially proportional to the control signal. 4. The scanning probe microscope apparatus according to claim 1, wherein the first moving unit moves the cantilever in the observation surface direction in response to a control signal input from the first moving amount control unit. The correction amount determining means is a means for moving, the data storage means for storing the detection error of the displacement amount detecting means in the form of correlation data with the control signal in advance, and the cantilever in the observation surface direction. And a data output means for reading the detection error corresponding to the control signal when moved from the correlation data stored in the data storage means and outputting this as a correction signal to the correction calculation means. Scanning probe microscope device. 5. The scanning probe microscope apparatus according to claim 1, wherein the first moving unit moves the cantilever in the observation surface direction according to a control signal input from the first moving amount control unit. The correction amount determining means is a means for moving, and the correction amount determining means stores the detection error of the displacement amount detecting means in the form of correlation data with the first movement amount in advance, and the cantilever performs the observation. Data output means for reading the detection error corresponding to the control signal when moving in the surface direction from the correlation data stored in the data storage means, and outputting this as a correction signal to the correction calculation means. A scanning probe microscope apparatus characterized by the above. 6. The scanning probe microscope apparatus according to claim 1, wherein the first and second moving means are the first
And a piezoelectric element for moving the cantilever in the direction of the observation surface and in a direction perpendicular to the observation surface according to a control signal input from the second movement amount control means. . 7. The scanning probe microscope apparatus according to claim 1, wherein the sample can be two-dimensionally moved in a plane substantially parallel to an observation surface, and the first movement means can perform a first movement. A scanning probe microscope apparatus, further comprising a sample moving means capable of moving a larger amount than the moving amount. 8. The scanning probe microscope apparatus according to claim 1, wherein the displacement amount detecting means includes a laser light source and a condenser lens for irradiating the cantilever with a laser beam, and a reflected light of the laser beam by the cantilever. A light receiving element that receives light and outputs a light receiving position signal corresponding to this light receiving position as a displacement amount signal, and the correction calculating means receives the light receiving position signal and the correction signal and outputs the corrected displacement amount signal. A scanning probe microscope apparatus comprising a position detection circuit. 9. The scanning probe microscope apparatus according to claim 1, wherein the displacement detection means includes a metal probe and measures a tunnel current flowing between the metal probe and the cantilever to measure the cantilever. A scanning probe microscope apparatus, which is a tunnel microscope that detects a displacement amount.