JPH06300513A - Probe position control method, scanning tunnelling microscope and record reproducing device - Google Patents

Abstract

PURPOSE:To accurately conduct feedback control of an elastic probe. CONSTITUTION:A tunnel current Jt detected by an elastic probe 40 is transformed into a transformed voltage Vt by a current/voltage transforming circuit 21 and then inputted to a Z-servo circuit 23 via a logarithmic transforming circuit 22. In the Z-servo circuit 23, based on a logarithmic voltage LogVt from the logarithmic transforming circuit 22 and a gain parameter PG from an FB loop gain setting circuit 26, a distance control signal SL is prepared for driving-control a Z-fine movement mechanism 25 so that a distance between an elastic probe 40 and an observed sample 1 may be constant. The distance control signal SL is inputted to the Z-fine movement mechanism 25 after being amplified by an amplifier 24. Consequently, since the elastic probe 40 is bimorph- driven by the Z-fine movement mechanism 25, distance between the elastic probe 40 and the observed sample 1 is held constant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a probe position control method, a scanning tunneling microscope and a recording / reproducing apparatus.

[0002]

2. Description of the Related Art In recent years, a scanning tunneling microscope (STM) has been developed which can directly observe the electronic structure of surface atoms of a conductor, and enables real space images to be measured with high resolution regardless of whether it is a single crystal or an amorphous material. (G. Binnig et al., Ph
ys. Rev. Lett., 49, 57, 1982). A scanning tunneling microscope uses a tip from the surface of a conductive substance in a state where a voltage is applied between the metal tip (probe) and the conductive substance.
The tunnel current flowing between the tip and the conductive substance is used when the distance is approached to a distance of about nm. The magnitude of this tunneling current depends on the distance between the tip and the surface of the conductive material and is very sensitive to changes in this distance. Therefore, by scanning the tip so that the magnitude of the tunnel current is kept constant,
It becomes possible to read various information about all electron clouds in the real space. At this time, the in-plane resolution of the conductive substance is about 0.1 nm.

By applying the principle of such a scanning tunneling microscope, the atomic order (sub-nanometer) can be sufficiently obtained.
It is possible to perform high-density recording / reproduction in. For example, in the recording / reproducing apparatus disclosed in Japanese Patent Laid-Open No. 61-80536, information is recorded by removing atomic particles adsorbed on the surface of the recording medium by an electron beam or the like, and a scanning tunneling microscope is used. Then, the recorded information is reproduced.

Further, as the recording layer, a material having a memory effect on the switching characteristics of voltage and current (for example, π
A method of performing recording / reproducing with a scanning tunneling microscope using a thin film layer of an electronic organic compound or a chalcogen compound is disclosed in JP-A-63-161552 and JP-A-63-16.
It is disclosed in Japanese Patent No. 1553. According to this method
If the recording bit size is 10 nm, then 10 ¹² bits
High-capacity recording / playback of as high as / cm ² is possible.

Further, for the purpose of downsizing, a plurality of microprobes with tips provided at the tip are formed on a semiconductor substrate, and information is recorded by displacing the probes with a recording medium facing each tip. The recording apparatus to be used is disclosed in JP-A-62-281138 and JP-A-1-
It is disclosed in Japanese Patent Publication No. 196751. For example, 1c
5 2500 probes on a silicon chip of m ² square
By combining the 0x50 matrix-type multi-probe head with the above-mentioned material having a memory effect, it is possible to record / reproduce digital data of 400 Mbit per tip and a total recording capacity of 1 Tbit.

At this time, a tip is mounted on a cantilever (cantilever beam) having a length of several 100 μm to form a cantilever-shaped microprobe, and the cantilever-shaped microprobe is composed of a piezoelectric body and driven. A method is being considered. Conventionally, as a method of producing such a cantilever, a method of producing a cantilever having a multi-layer structure such as a piezoelectric thin film or a metal film by applying a semiconductor process and using a processing technique for performing fine processing on one substrate has been used. Yes (TRAlbrecht et al., “Mic
rofabrication of integrated scanning tunneling mic
roscope ”, Proceedings of 4th International Confer
ence on scanning tunneling microscope / spectroscop
y, 1990).

[0007]

Conventionally, the microprobe and the multi-probe head in which the microprobe is integrated have been manufactured by applying an IC process. In other words, a cantilever type probe with a tip formed on the probe tip is created using photolithography technology,
A microprobe and a multiprobe head have been proposed in which this cantilever is driven by piezoelectric power or electrostatic force. However, since the microprobe formed by such a photolithography technique is not large in size, it does not have such a large elastic constant. Therefore, when the microprobe is brought close to the recording medium or the sample facing the microprobe and the current flowing between them is used to construct the recording / reproducing apparatus or the scanning tunneling microscope, there are the following problems.

(1) As described above, when the microprobe is brought close to the sample (recording medium), the tip of the tip and the van der Waals force, the surface tension of the liquid such as water, and the electrostatic force due to the voltage applied between them. The attraction force due to Due to the balance between this force and the elastic force of the flexure of the actuator, when the tip of the tip is brought close to the sample, the cantilever bends when the tip of the tip reaches the unstable point and the tip of the tip reaches the sample. Is adsorbed, and at this time, the detection current from the tip suddenly reaches a certain value. Under such a suction state, the amount of displacement of the tip is greatly reduced as compared with the state in which the tip of the tip is free. Therefore, if feedback control is performed in this state in which the current flowing between the tip of the tip and the sample is constant, the control results are much worse than when the tip is free. Therefore, when the microprobe is used for recording / reproducing in this state, the distance between the two is greatly changed when the probe is accessed on the sample, resulting in deterioration of recording / reproducing performance. Further, when used in a scanning tunneling microscope, correct information on the surface roughness of the sample could not be obtained.

(2) Further, when a multi-probe head in which microprobes are integrated is produced, the probe performance varies due to process variations and the like. At this time, if the mechanical characteristics of the probe, in particular, the elastic constants vary, the amount of decrease in the displacement of the probe tip varies when the probe comes into contact, and the control performance varies from probe to probe.
For this reason, in the recording / reproducing apparatus using the multi-probe in which a plurality of microprobes are integrated, the signal varies from probe to probe, and the desired performance cannot be obtained.

It is an object of the present invention to provide a probe position control method, a scanning tunnel microscope and a recording / reproducing apparatus which can accurately perform feedback control of an elastic probe.

[0011]

According to the probe position control method of the present invention, a conductive tip provided at the tip of an elastic probe flows between the conductive tip and the sample when the sample is brought into contact with the sample. In a probe position control method for controlling the position of the elastic probe by using an electric current, a decrease in displacement of the tip of the elastic probe caused by contact between the conductive tip and the sample is corrected.

Here, the decrease in displacement of the tip of the elastic probe may be corrected by correcting the gain of a control loop for controlling the distance between the conductive tip and the sample.

Alternatively, when the conductive tips of the multi-probe head in which a plurality of elastic probes having conductive tips are integrated are brought into contact with a sample, the conductive tips and the sample are separated from each other. In the probe position control method for controlling the position of each elastic probe by using each current flowing therebetween, displacement of the tip of each elastic probe caused by contact between each conductive tip and the sample. Correct each decrease.

Here, by correcting the gain of each control loop for controlling the distance between each conductive tip and the sample, the displacement decrease of the tip of each elastic probe is corrected. May be.

The scanning tunneling microscope of the present invention comprises a multi-probe head in which a plurality of elastic probes each having a conductive tip on its tip are integrated, and each of the conductive tips when the conductive tip is brought into contact with a sample. In a scanning tunneling microscope including a plurality of control means for controlling the position of each elastic probe by using each current flowing between a conductive tip and the sample, a control loop of each control means It includes a plurality of correction means for respectively correcting the gain.

Here, it may further include storage means for storing the correction amounts of the correction means, and storage means for storing feedback parameters of the control means. .

The recording / reproducing apparatus of the present invention comprises a multi-probe head in which a plurality of elastic probes each having a conductive tip on its tip are integrated, and the conductive tips when the conductive tips are brought into contact with a sample. In a recording / reproducing apparatus including a plurality of control means for controlling the position of each elastic probe by using each current flowing between the sample tip and the sample, the gain of the control loop of each control means is set. It includes a plurality of correction means for correcting each.

Here, it may further include storage means for storing the correction amounts of the correction means, and storage means for storing feedback parameters of the control means. .

[0019]

According to the probe position control method of the present invention, the feedback control of the elastic probe can be accurately performed by correcting the displacement reduction of the tip of the elastic probe caused by the contact between the conductive tip and the sample. it can. Specifically, the decrease in displacement of the tip of the elastic probe may be corrected by correcting the gain of the control loop for controlling the distance between the conductive tip and the sample.

The scanning tunneling microscope of the present invention can accurately perform feedback control of the elastic probe by including a plurality of correction means for correcting the gain of the control loop of each control means.

The recording / reproducing apparatus of the present invention can accurately perform feedback control of the elastic probe by including a plurality of correcting means for respectively correcting the gains of the control loops of the respective controlling means.

[0022]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram showing an embodiment of the scanning tunneling microscope of the present invention.

The scanning tunneling microscope 10 includes an XY fine movement drive mechanism 11, an XY fine movement drive circuit 12, a bias circuit 13, an elastic body probe 40 having a conductive tip 49 at its tip, and a current-voltage conversion circuit 21. , Logarithmic conversion circuit 22, Z servo circuit 23, amplifier 24, Z fine movement mechanism 25, and feedback loop gain setting circuit (hereinafter referred to as “FB loop gain setting circuit 26”).
A control circuit 30, a switch circuit 31, and a display 32. Each component of the scanning tunneling microscope 10 will be described in detail below.

(1) XY fine movement drive mechanism 11, XY fine movement drive circuit 12 and bias circuit 13 The XY fine movement drive mechanism 11 has the conductive tip 49 in the X-axis direction and the Y-axis direction in the figure with respect to the surface of the observation sample 1. Each is for scanning. XY fine movement drive circuit 1
2 is for driving the XY fine movement drive mechanism 11. The bias circuit 13 is for applying a predetermined bias voltage between the conductive tip 11 and the observation sample 1.

(2) Elastic Body Probe 40 The elastic body probe 40 is specifically shown in FIG.
As shown in (B), respectively, the silicon substrate 41, the first SiNx layer 42, the first driving electrode 43, and the first
Piezoelectric thin film 44, a second driving electrode 45, a second piezoelectric thin film 46, a third driving electrode 47, and a second S electrode.
The iNx layer 48 includes a sharp conductive tip 49 for detecting the tunnel current J _t , and a tip electrode 50. That is, the elastic body probe 40 is a cantilever having a bimorph structure, and when a predetermined voltage is applied to each of the first to third driving electrodes 43, 45, and 47, a reverse piezoelectric effect is applied to the upper and lower sides in the drawing. Displace in the direction.

In order to manufacture the elastic probe 40, for example, a Si ₃ N ₄ film having a thickness of 0.15 μm is formed on a silicon (100) substrate 41 having a thickness of 0.5 μm by the CVD method. The source gas used at this time is SiH ₂ Cl ₂ : N
H ₃ (1: 9) and the substrate temperature is 800 ° C. Then, the Si ₃ N ₄ film is patterned into a desired shape by photolithography and CF ₄ dry etching to form a first SiNx layer 42. Then, a 0.01 μm thick Cr film and a 0.09 μm thick Au film are formed.
After forming the film, the Cr film and the Au film are patterned into a desired shape by photolithography and wet etching to form the first driving electrode 43.
Then, an AlN film (piezoelectric thin film) having a thickness of 0.3 μm is formed by a sputtering method. At this time, Al is used as a target and sputtering is performed in an Ar + N ₂ atmosphere. Subsequently, the AlN film is patterned into a desired shape by photolithography and wet etching with an Al etchant to form a first piezoelectric thin film 44.

Thereafter, in the same manner as in the above step, the second drive electrode 45, the second piezoelectric thin film 46 and the third drive electrode 47 are sequentially formed to form the silicon substrate.
Au / Cr-AlN-Au / Cr-AlN-Au / Cr
Form the bimorph structure of. Then, as a protective layer,
A second SiNx layer 48 is formed by depositing amorphous SiN having a thickness of 0.15 μm by the CVD method. Subsequently, a conductive tip 49 made of tungsten (W) is formed by a vapor deposition method, and then a portion without a Si ₃ N ₄ film is removed by anisotropic etching of silicon by KOH to manufacture a cantilever. . Finally, the conductive tip 49 is Pt coated.

The size of one cantilever manufactured as described above is 500 μm in length × 100 μm in width,
The resonance frequency in the Z-axis direction shown in FIG. 1 is 2.3 kHz,
The average amount of displacement of the bimorph when 1 V is applied is 1.5 μm. Further, in the free state, the elastic constant k _P of the deflection of the piezoelectric bimorph in the Z-axis direction is k _P ≈
It is calculated as 0.01 N / m.

[0030] ^{_{k P = b × t 3/}} 4 × L 3 × E (1) However, E = cantilever Young's modulus b = cantilever density t = cantilever thickness L = length of the cantilever Furthermore, conductive tip 49 has a radius of curvature of about 0.
Assuming that the coating layer is 1 μm and the coating layer is an organic material, and the Young's modulus thereof is about 10 ⁻⁹ N / m ² , the elastic constant k _S ≈1 N / m for the recess of the coating layer was estimated.

(3) Current / voltage conversion circuit 21, logarithmic conversion circuit 22, Z servo circuit 23, amplifier 24 and FB loop gain setting circuit 26 Current / voltage conversion circuit 21, logarithmic conversion circuit 22, Z servo circuit 23, amplifier 24 and FB loop gain setting circuit 2
Reference numeral 6 denotes the elastic probe 40 and the observation sample 1 when observing the sample.
This is to apply a servo so that the distance between and becomes constant. That is, the tunnel current J _t detected by the elastic body probe 40 is converted into the converted voltage V _t by the current-voltage conversion circuit 21, and then input to the Z servo circuit 23 via the logarithmic conversion circuit 22. In the Z servo circuit 23, the output signal of the logarithmic conversion circuit 22 (logarithmic voltage Log
(V _t )) and the gain parameter P _G which is the output signal of the FB loop gain setting circuit 26, the elastic probe 40 is set so that the distance between the elastic probe 40 and the observation sample 1 becomes constant. A distance control signal S _{L for} drive control is created. The distance control signal S _L is amplified by the amplifier 24 and then input to the elastic body probe 40. As a result, when the elastic body probe 40 is bimorph-driven,
The distance between the elastic body probe 40 and the observation sample 1 is kept constant. The Z fine movement mechanism 25 including a laminated piezoelectric element is used when the elastic body probe 40 is largely moved in the Z axis direction.

Here, in the Z servo circuit 23, as shown in FIG. 3, the logarithmic voltage Log (V _t ) is input to the plus input terminal and the predetermined distance set value Z ₀ is input to the minus input terminal. Output signal of the variable gain amplifier 102 and the variable gain amplifier 102 in which the error signal e which is the output signal of the subtractor 101 is input to the input terminal and the gain parameter P _G is input to the control terminal. Low-pass filter with cut-off frequency f _C
103 and a correction circuit 104 to which the distance control signal S _L which is the output signal of the low-pass filter 103 and the gain parameter P _G are respectively input. The output signal of the correction circuit 104 is used as the correction distance control signal S in the switch circuit 31.
(See FIG. 1).

The magnitude of the logarithmic voltage Log (V _t ) input from the logarithmic conversion circuit 22 to the plus input terminal of the subtractor 101 is proportional to the distance between the conductive tip 49 and the observation sample 1 (tip And the current between the samples is a tunnel current), the Z servo circuit 23 outputs the distance control signal S _L so that the magnitude of the logarithmic voltage Log (V _t ) becomes constant. Therefore, in the Z servo circuit 23, the subtractor 101 subtracts the logarithmic voltage Log (V _t ) from the distance setting value Z ₀ to generate the error signal e. Then, the error signal e is
From the FB loop gain setting circuit 26 to the variable gain amplifier 10
Amplification is carried out at an amplification factor according to the gain parameter P _G sent to the unit 2. The error signal e amplified by the variable gain amplifier 102 passes through the low-pass filter 103 to remove high frequency components, and then the distance control signal S _L
Is output to the amplifier 24 (see FIG. 1). Further, the distance control signal S _L output from the low pass filter 103
Is corrected by the correction circuit 104 according to the gain parameter P _G sent from the FB loop gain setting circuit 26 to the correction circuit 104, and is output to the switch circuit 31 as a correction distance control signal S. The corrected distance control signal S is output to the display 32 as a topo signal representing the surface irregularities of the observation sample 1.

The FB loop gain setting circuit 26 will be described.
Of the conductive tip 49 of the elastic probe 40.
Not generated due to the attraction force acting between the tip and the observation sample 1.
Fig. 4 (A) to (C) for the contact state of both
Explanations will be given with reference to each. FIG. 4A shows a conductive tip.
49 shows the state in which the observation sample 1 and the observation sample 1 are in contact with each other by the attraction force.
It is a figure. When performing STM observation in the atmosphere,
Surface of observation sample 1 (or tip of conductive tip 49)
Must be covered with a very thin insulating cover layer 201.
Many. Therefore, the conductive tip 49 has the coating layer 201.
The tunnel current from the surface of the observation sample 1 is detected via the
It At this time, the tip of the conductive tip 49 and the coating layer 201
A repulsive force due to contact acts between and. With this repulsive force
Therefore, elastic deformation of the elastic body probe 40 is generated.
In addition, concave elastic deformation occurs in the coating layer 201. Figure
4 (B) is a conductive tip in the initial state of contact.
The tip of 49 came into contact with the coating layer 201 on the surface of the observation sample 1.
At the time, the position of the base of the elastic probe 40, the conductive tip
Position of tip of tip 49 and surface of observation sample 1
It is a figure which shows the model showing. Where the elastic probe
The root of 40 means that the elastic probe 40 is the Z fine movement mechanism 25.
The part that is joined to. As shown in the figure, elasticity
The base of the body probe 40, the tip of the conductive tip 49, and
The surface of the observation sample 1 is bent by the elastic probe 40.
The elastic body related to the deflection of the covering layer 201
It will be in a state of being connected to each other. Where the elastic probe
The elastic constant of the flexure of 40 is represented by "k_P And the coating layer 201
The elastic constant is “k_S From this state, the elastic body
Move the valve 40 to “ΔZ_d "Only close to the surface of observation sample 1
The tip of the conductive tip 49 is “Δ
Z_S It is assumed that it has been displaced only by "(see Fig. 4C).
Consider the force balance of the tip of the mushroom conductive tip 49.
And k_P × (ΔZ_d-ΔZ_S) = K_S × ΔZ_S (2) holds. If the above equation (2) is modified, ΔZ_S= K_P × ΔZ_d/ (K_P + K_S ) (3) holds. From the above formula (3), the elastic body probe 40
Actual displacement of the tip of the conductive tip 49 when driven
The amount is k compared to the driving amount of the elastic body probe 40. _P /
(K_P + K_S ) Will only decrease. For example, bullet
Elastic constant k of the sex probe 40_P Is about 0.01 N / m
And the elastic constant k of the coating layer 210_S Is about 1 N / m,
The displacement reduction amount of the tip of the conductive tip 49 is about 1/10.
It will be about 0.

As described above, it was found that the displacement of the tip of the conductive tip 49 is greatly reduced when the tip of the conductive tip 49 is in contact with the tip. However, this influences the position control of the elastic probe 40. About Figure 5
This will be described in detail with reference to (A), (B) and FIG. 6, respectively.

FIG. 5A shows the elastic probe 40 of FIG.
It is a block diagram showing a control system usually used when performing position control in the illustrated Z-axis direction. This control system is a first block corresponding to the conductive tip 49 that detects a change in the tunnel current J _t from the displacement Z of the tip of the conductive tip 49.
301, a second block 302 corresponding to the subtractor 101 of the current-voltage conversion circuit 21, the logarithmic conversion circuit 22, and the Z servo circuit 23 for obtaining an error signal e of a linear signal with respect to the displacement Z from the tunnel current J _t ; A third block 303 corresponding to the variable gain amplifiers 102 to 24 of the Z servo circuit 23 for obtaining the applied voltage V to the elastic body probe 40 from the signal e, and the conversion of the applied voltage V to the elastic body probe 40 to the displacement Z. And a fourth block 304 showing the characteristics. In the figure, “A”, “B” and “G ₁ ” represent constants, “G ₂ (s)” represents the transfer characteristic of the variable gain amplifier 102 of the Z servo circuit 23 to the amplifier 24, and G
₃ (s) ”indicates the transfer characteristic of conversion from the applied voltage V of the elastic probe 40 to the displacement Z. On the other hand, the conductive tip 4
The tip of 9 comes into contact with the conductive tip 49 as described above.
As shown in FIG. 5B, the control system in the case where the displacement of the tip of the is decreased is the fourth block 304 and the first block 301.
And a fifth block 305 corresponding to the reduction of the displacement of the tip of the conductive tip 49 is added between and. Here, the fifth block 305 has a gain of k _P / (k _P +
k _S ) as an attenuator. In the figure,
“Z ′” indicates the amount of displacement of the conductive tip 49. Figure 5
The influence of the difference between the control system shown in (A) and the control system shown in FIG. 5 (B) on the control performance will be described in detail below with reference to the frequency characteristic of the control system open loop gain characteristic shown in FIG. Explained. The cutoff frequency of the applied voltage-displacement conversion characteristic of the piezoelectric probe 40 is sufficiently high, and the Q value of the resonance frequency of the piezoelectric probe 40 is small.

The open loop gain characteristic of the control system shown in FIG. 5A is shown by the solid line in FIG. Where "f
_C ”is the low-pass filter 103 (FIG. 3) of the Z servo circuit 23.
Cut-off frequency of low-pass filter 10
When 3 has a first-order damping characteristic, the open loop gain is -2 when the frequency becomes higher than the cutoff frequency f _C.
It attenuates at a rate of 0 dB / dec. At this time, the servo response frequency in the Z-axis direction is the frequency f _{1 at} which the open loop gain crosses 0 dB. On the other hand, the open loop gain characteristic of the control system shown in FIG. 5 (B) is over the entire frequency range as shown by the broken line in FIG. 6 compared to the open loop gain characteristic of the control system shown in FIG. 5 (A). , The gain is “k _P / (k _P +
k _S ) ”. In this case, the servo response frequency in the Z-axis direction is frequency f ₂ , which is smaller than frequency f ₁ by“ k _P / (k _P + k _S ) ”. Even if the open loop gain is designed so that the response frequency of the Z servo when the elastic body probe 40 is in the free state is 1 kHz, the elastic constant k _S of the coating layer 201 is about 1 N / m, In the servo system in which the elastic constant k _P of the probe 40 is about 0.01 N / m, the response of the servo is only about 10 Hz.

Therefore, the FB loop gain setting circuit 26
(See FIG. 1), the elastic constant k _P of the elastic probe 40 is
And the elastic constant k _S of the coating layer 201, the amount of displacement reduction at the time of contact of the tip of the conductive tip 49 is estimated, and the gain parameter P _G is determined so as to compensate for this.
The gain of the variable gain amplifier 102 (see FIG. 3) of the Z servo circuit 23 is determined based on the determined gain parameter P _G. Thereby, the open loop gain of the control system is compensated. Further, the correctable circuit 104 of the Z servo circuit 23 corrects the distance control signal S _L output from the low-pass filter 103 on the basis of the gain parameter P _G , so that the actual tip displacement of the conductive tip 49 is displaced. A corrected distance control signal S indicating the quantity is created.

(4) Control Circuit 30, Switch Circuit 31, and Display 32 The control circuit 30 shown in FIG.
The bias circuit 13 and the Z fine movement mechanism 25 are respectively controlled, and the conversion voltage V _t sent from the current-voltage conversion circuit 21 is processed when the surface of the observation sample 1 is observed to create a tunnel current image. . The switch circuit 31 is for switching between the output signal of the control circuit 30 and the corrected distance control signal S generated by the Z servo circuit 23. The display 32 is for displaying the tunnel current image and the topo image of the observation sample 1 by the output signal of the control circuit 30 and the corrected distance control signal S sent from the switch circuit 31.

Next, the operation of the scanning tunneling microscope 10 will be briefly described.

At the time of observing the surface, a predetermined bias voltage is applied between the conductive tip 49 and the observation sample 1 by the bias circuit 1.
When the Z fine movement mechanism 25 is driven in the state of being applied from No. 3, the elastic body probe 40 is moved to such an extent that the tunnel current J _t of a predetermined value flows between the conductive tip 49 and the observation sample 1. After being brought close to the observation sample 1, the elastic body probe 40 is servo-controlled so that the distance between the two becomes constant. In this state, the XY fine movement drive circuit 12 drives the XY fine movement drive mechanism 11,
The conductive tip 49 is two-dimensionally scanned on the surface of the observation sample 1. At this time, the tunnel current J _t whose value changes due to minute irregularities on the surface of the observation sample 1 is detected by the conductive tip 49. Detected tunnel current J _t
Is converted into a converted voltage V _t by the current-voltage conversion circuit 21 and then taken into the control circuit 30. With the control circuit 30,
A tunnel current image is created by processing the conversion voltage V _t in synchronization with an XY scanning signal that causes the conductive tip 49 to two-dimensionally scan the surface of the observation sample 1. The tunnel current image is displayed on the display 3 via the switch circuit 31.
It is displayed in 2. In addition, when changing the observation place, X
The observation sample 1 is moved in the illustrated X-axis direction and Y-axis direction by a Y coarse movement mechanism (not shown in FIG. 1) to move the conductive tip 49 to a desired observation region, and then the observation is similarly performed. Is done.

During observation, the FB loop gain setting circuit 26
In, the displacement reduction amount at the time of contact is estimated to be 0.01, and the gain of the variable gain amplifier 102 is set so as to have a gain 100 times higher than the normal feedback loop gain so as to correct this reduction amount. The position control of the elastic body probe 40 in the illustrated Z-axis direction was performed. At this time, it was found from the closed loop gain response that the position control in the Z-axis direction in the figure follows up to about 1 kHz, which is close to the actuator performance limit. In this state, the conductive tip 49
While the bias voltage of 1 V is applied from the bias circuit 13 to the observation sample 1, the Z fine movement mechanism 25 is driven so that a tunnel current J _{t of} 1 nA flows between the conductive tip 49 and the observation sample 1. After bringing the conductive tip 49 close to the observation sample 1, the elastic probe 40 was controlled by the Z servo circuit 23 so that the distance between them was constant. In this state, the XY fine movement drive circuit 12 drives the XY fine movement drive mechanism 11 to observe the surface of the observation sample 1. At this time, even if the frequency in the main scanning direction is set to about 100 Hz and the scanning of the conductive tip 49 is performed at high speed, the correction distance control signal S corresponding to the minute irregularities on the surface of the observation sample 1 can be created, and stable scanning is performed. Type tunnel microscope image (ST
M image) could be displayed on the display 32.

The scanning tunneling microscope 1 of this embodiment is used.
In No. 0, the elastic body probe 40 has a bimorph structure of a thin film piezoelectric actuator.
Instead of an actuator, as a current detection type micro current probe, this micro current probe may be attached to a fine movement driving element such as a laminated piezoelectric element to control in the Z-axis direction.

Next, a first embodiment of the recording / reproducing apparatus of the present invention will be described with reference to FIG.

The recording / reproducing apparatus 600 comprises a structure 611, a base 612 on which a recording medium 601 is placed, and a Z actuator 61.
3, a multi-probe head 614 having 4 × 4 probes 614 _{11 to} 614 ₄₄ , an XY actuator 615, a probe head control circuit 616, a Z servo circuit 617, and F
B loop gain setting circuit 618 and cantilever drive circuit
619, inclination correction circuit 620, voltage application circuit 621, scanning circuit 622, tracking control circuit 623, and addition circuit
624, includes an encoder 625 and a decoder 626. Next, each component of the recording / reproducing apparatus 600 will be described in detail.

(1) The structure 611, the base 612, and the Z actuator 613 structure 611 have a sealed internal space. A base 612 on which the recording medium 601 is mounted is attached to the bottom surface inside the structure 611 via a Z actuator 613, and the Z actuator 613 moves the Z axis direction in the drawing.
It is moved in the α rotation direction and the β rotation direction respectively in the figure. It should be noted that the surface of the recording medium 601 is formed with concave grooves having a width of 200 nm and a depth of 30 nm at a pitch of 2 μm in the X-axis direction shown in the figure along with a length of 100 μm in the Y-axis direction shown by fine processing such as a semiconductor process. ×
4 sets of strip-shaped, tracking pattern 602 is formed for the position control of each probe 14 _{11-14 44.} Further, the recording medium 601 is formed on a flat substrate such as glass or mica, a substrate electrode formed of an epitaxial growth surface of gold grown on this substrate, on which each tracking pattern 602 is formed, and on this substrate electrode. In addition, it is composed of a monolayer bilayer cumulative film of squarylium-bis-6-octylazulene (hereinafter referred to as "SOAZ"). Here, SOAZ is a material having a memory effect on the switching characteristics of voltage and current, and can be formed by a known Langmuir-Projet method.

(2) Multi-probe head 614 and X
Y Actuator 615 Multi-probe head 614 is a 4 × 4 probe 614.
And has a _{11 to 614 44.} Where each probe 614
_As shown in FIG. 8, _{11 to} 61 ₄₄ are arranged at positions facing each tracking pattern 602 formed on the surface of the recording medium 601, at a pitch of 1 mm (W ₁ = W ₁ =
1 mm) and a pitch of 200 μm (L
₁ = 200 μm). The multi-probe head 614 is attached to the upper surface inside the structure 611 via the XY actuator 615 so as to be close to the surface of the recording medium 601 and face each other.
Are moved in the X-axis direction and the Y-axis direction shown in FIG. Each of the probes 614 _{11 to} 614 ₄₄ was made in the same manner as the elastic probe 40 shown in FIG.
It includes a cantilever type actuator in which a piezoelectric thin film such as 1N and a metal thin film are laminated.

(3) Probe head control circuit 616 The probe head control circuit 616 is arranged so that each of the probes 614 _{11 to} 614.
Each tunnel current signal J _t11 output from ₄₄
Receive J _t44, the tunnel current signal J _t11 through J _t44
Is output to the Z servo circuit 617 and the decoder 626.

(4) The Z servo circuit 617, the FB loop gain setting circuit 618, the cantilever drive circuit 619, and the inclination correction circuit 620 The Z servo circuit 617 receives the tunnel current signals J _{t11 to} J _t44 from the control circuit 616. Z direction drive signals A _{11 to} A _{44 for} changing the distances between the probes 614 _{11 to} 614 ₄₄ and the surface of the recording medium 601 so that the values become predetermined values.
And outputs the generated Z-direction drive signals A _{11 to} A ₄₄ to the cantilever drive circuit 619 and the tilt correction circuit 620, respectively. The cantilever drive circuit 619 is a Z servo circuit.
617 in accordance with the Z-direction driving signal A ₁₁ to A ₄₄ inputted from, by applying respectively a predetermined voltage to the first to third driving electrodes of each probe 614 _{11-614 44} (see FIG. 2) , The probes 614 _{11 to} 614 ₄₄ are displaced in the Z-axis direction in the drawing. The tilt correction circuit 620 creates a tilt correction signal D for changing the tilt of the multi-probe head 614 according to the Z-direction drive signals A _{11 to} A ₄₄ input from the Z servo circuit 617, and outputs it to the Z actuator 613. The FB loop gain setting circuit 618 is similar to the FB loop gain setting circuit 26 shown in FIG.

[0050] (5) a voltage application circuit 621 voltage application circuit 621 is for applying various voltages between the respective probe 614 _{11-614 44} and the recording medium 601.

(6) Scanning circuit 622, tracking control circuit 623 and addition circuit 624 The scanning circuit 622, the tracking control circuit 623 and the addition circuit 624 are arranged on the surface of the recording medium 601 while tracking control of the probes 614 _{11 to} 614 _44. For two-dimensional scanning.

(7) Encoder 625 and Decoder 626 Encoder 625 records information (data) input from the outside.
Is encoded and the record information is converted into binary data of “0” or “1”. The converted binarized data is transmitted to each probe 614 _{11 to} 6 via the probe head control circuit 616.
_Entered in 14 ₄₄ . The decoder 626 converts the reproduced binarized data into recording information (data) and then outputs it to the outside.

Next, the operation of the recording / reproducing apparatus 600 will be described.

By driving the Z actuator 613, the multi-probe head 614 is brought closer to the recording medium 601. Since each of the probes 614 _{11 to} 614 ₄₄ has an elastic constant smaller than that of the surface of the recording medium 610, when all the probes 614 _{11 to} 614 ₄₄ collectively approach the recording medium 601, the elastic cantilever Due to the deformation, the force acting between them can be kept below a certain level. As a result, upon contact,
It is possible to prevent damage to the tip electrode surface and the probe 614 _{11-614 44} of the recording medium 601. When recording / reproducing, each probe 614 _{11 to} 614 of the multi-probe head 614
_{Reference numeral 44} approaches the recording medium 601 to such an extent that tunnel currents respectively flow. The tunnel current signals J _{t11 to} J _t44 output from the probes 614 _{11 to} 61 ₄₄ are input to the Z servo circuit 617 via the probe head control circuit 616. In the Z servo circuit 617, the Z direction drive signals A _{11 to} A ₄₄ for keeping the distances between the probes 614 _{11 to} 614 ₄₄ and the recording medium 601 constant are the tunnel current signals J _{t11 to} J _t.
Each is created based on _t44 . The generated Z-direction drive signals A _{11 to} A ₄₄ are applied to the first to third drive electrodes (see FIG. 2) of the probes 614 _{11 to} 614 ₄₄ via the cantilever drive circuit 619. In addition, the tilt correction circuit 620 creates a tilt correction signal D for correcting the tilt between the multi-probe head 614 and the recording medium 601 based on the Z-direction drive signals A _{11 to} A ₄₄ , and outputs the tilt correction signal D to the Z actuator 613. Is output.

At the time of recording / reproducing, an XY scanning signal is output from the scanning circuit 622 to the multi-probe head 614, which causes the multi-probe head 614 to scan the recording medium 601 in the X-axis direction and the Y-axis direction in the figure, respectively. It At this time, the tracking control circuit 623, the tracking pattern edge position is detected from the change in the tunnel current detected by the probe 614 _{11-614 44.} Based on the detection result, the positional deviation between the tracking pattern 602 and the multi-probe head 614 is corrected by the XY actuator 615. In this state, the recording voltage is applied from the voltage applying circuit 612 between each probe 614 _{11-614 44} and the recording medium 601, and a tunnel current is modulated, recorded bit on the recording medium 601 is formed To be done.

The control of the multi-probe head 614 in the Z-axis direction in the recording / reproducing apparatus 600 will be described below in detail with reference to FIG.

The Z servo circuit 617 controls the probe head.
Timing from circuit 616, each probe 614₁₁~ 614₄₄
Each tunnel current signal J from_t11~ J_t44The digital signal
Each probe 614
₁₁~ 614₄₄Sequentially generate each control signal to control the Z axis direction
Yes, it has a digital servo system configuration. Z servo circuit 61
7 is a selection circuit 701 as shown in FIG.
, A / D conversion circuit 702, logarithmic conversion circuit 703, and
Set value Z₀ Is input to the minus input terminal
704, gain correction circuit 705, and each probe 614₁₁~ 6
14₄₄Correction amount G for each ₁₁~ G₄₄Memory 706 in which is stored
, PI control circuit 707, D / A conversion circuit 708, and switching
Circuit 709.

The tunnel current signals J _{t11 to} J _t44 from the probes 614 _{11 to} 61 ₄₄ are _transmitted to the probe head control circuit 616.
Are input to the selection circuit 701 via. Selection circuit
In 701, only one of the tunnel current signals J _{t11 to} J _t44 is selected according to the timing from the probe head control circuit 616 (hereinafter, the selected tunnel current signal is referred to as “tunnel current signal J _tn ”). .). The selected tunnel current signal J _tn is converted into a digital signal by the A / D converter 702 (hereinafter, the tunnel current signal J _tn converted into a digital signal will be referred to as “digital tunnel current signal J _tn (t)”). Called.). Digital tunnel current signal J
_The logarithmic conversion circuit 703 logarithmically converts _tn (t) into linearization with respect to the distance between the probe and the recording medium 601 (hereinafter, linearized digital tunnel current signal J _tn (t). ) Is defined as “Linearized digital tunnel current signal Lo
gJ _tn (t) ”. ). The linearized digital tunnel current signal LogJ _tn (t) is input to the plus input terminal of the subtractor 704, and is subtracted from a predetermined set value Z ₀ by the subtractor 704 to be converted into an error signal e _n (t). It

At this time, in the memory 706, the address corresponding to the probe selected by the selection circuit 701 is designated by the probe head control circuit 616, and the correction amount G _{n of the} selected probe is stored in the memory. It is output from the 706 to the correction circuit 705. The correction amounts G _{11 to} G ₄₄ stored in the memory 706 are created by the FB loop gain setting circuit 618 so as to compensate the displacement reduction amount due to the contact. In the correction circuit 705, the correction error signal e _n (t) ′ is created by multiplying the error signal e _n (t) by the correction amount G _n . The PI control circuit 708 generates a distance control signal U _n (t) that displaces the distance between the selected probe and the recording medium 601 so that the correction error signal e _n (t) ′ becomes zero. The distance control signal U _n (t) is
After being converted into an analog signal by the D / A converter 708, it is applied by a switching circuit 709 to an actuator that drives the selected probe in the Z-axis direction.

The probe head control circuit 616 sequentially switches the probe to be selected while storing the distance control signal U _n (t) corresponding to each probe number, and applies the same to all the probes 614 _{11 to} 614 ₄₄ . Then, control in the Z-axis direction is performed. After the distance control signal is applied to the actuator once, the actuator is in a floating state until the distance control signal is applied to the same actuator again. That is, during this period, the control voltage is held by the capacitance between the electrodes of the actuator, and the displacement of the actuator is maintained. As a result, it is possible to correct the decrease in Z servo response due to the displacement reduction of all the probes 614 _{11 to} 61444 and its variation, and by inputting the corrected error signal to the PI control circuit 707, all the probes 614 ₁₁ to 614 ₄₄ can be corrected. for 614 _44, with same accuracy and to frequencies close to the performance limits of the actuators, it is possible to perform servo control.

Next, the recording / reproducing performed while applying the servo as described above will be described.

Each probe 61 of the multi-probe head 614
When 4 _{11-614 44} tips of contacts the surface of the recording medium 601, the surface is elastically deformed in the recording medium 601, a tunnel current flows between the tip and the substrate electrode. 16 probes
The elastic constants k _P of 614 _{11 to} 614 ₄₄ were about 0.01 N / m ± 10%, like the elastic probe 40 shown in FIG. Furthermore, the radius of curvature of the tip of the tip is about 0.1 μm.
And the Young's modulus of the organic material of the recording medium 601 is about 10 ⁻⁹ N
/ M ² , the elastic constant k for the concave of the recording medium 601
_S was estimated to be about 1 N / m. Therefore, in the FB loop gain setting circuit 618, the displacement reduction amount at the time of contact is 0.01
Estimated at 10% ±, so as to correct the displacement reduction, after the correction amount G ₁₁ ~G ₄₄ of each probe 614 _{11-614 44} is created, stored in the memory 706.

Recording of recording information was performed as follows. Between each probe 614 _{11-614 44} and the recording medium 601, a bias voltage of 0.1 V, to the extent that a constant tunnel current (1 nA) flows, each probe 614 ₁₁
Each of the recording medium 601 and the recording medium 601 was brought up to 614 ₄₄ . Each of the probes 614 _{11 to} 614 ₄₄ was independently driven in the Z-axis direction by the Z servo circuit 617, and feedback control was performed so that a tunnel current of 1 nA would flow. Further, an inclination correction signal D for correcting the inclination between the multi-probe head 614 and the recording medium 601 is created based on the Z-direction drive signals A _{11 to} A ₄₄ and output to the Z actuator 613. In this state, after moving each probe 614 _{11 to} 61 ₄₄ to a desired position on the recording medium 601, the bias voltage is modulated and a 6V pulse voltage is applied to a predetermined probe 614 _{11 to} 614 _44.
When applied between the recording medium 601 and the recording medium 601, it is instantaneously about 0.1.
A recording bit (10
nmφ recording bit) was formed. When scanning was performed after application of the pulse voltage, the state was maintained. Therefore, the recording bit in the low resistance state is associated with "1" and the recording bit in the high resistance state is associated with "0". Then, the encoder 625 encodes the recording information (data) input from the outside into binary data of “0” and “1”, and the decoder 626 reproduces the binary data, Recording and reproduction of the digitized data were performed.

Next, a second embodiment of the recording / reproducing apparatus of the present invention will be described with reference to FIG.

The recording / reproducing apparatus of this embodiment is different from the recording / reproducing apparatus 600 shown in FIG. 7 in that it has the Z servo circuit shown in FIG. That is, the Z servo circuit is the selection circuit.
801, an A / D conversion circuit 802, a logarithmic conversion circuit 803,
A subtractor 804 having a predetermined set value Z ₀ input to its negative input terminal, a PI control circuit 806, and a PI control circuit 806.
The control parameters K _{11 to} K ₄₄ of each probe are 614 _{11 to} 614 _44.
Memory 807 and D / A conversion circuit 808 stored for each
And a switching circuit 809.

Each probe 814₁₁~ 814₄₄From each tunnel
Current signal J_t11~ J_t44Is the probe head control circuit (not
Input to the selection circuit 801 via the respective channels. Election
The selection circuit 801 uses the timing from the probe head control circuit.
Each tunnel current signal J_t11~ J_t44one of
Only selected (hereinafter, selected tunnel current signal
"Tunnel current signal J_tn". ). Selected
Tunnel current signal J _tnIs a digital converter with A / D converter 802.
Converted to digital signals (hereinafter, converted to digital signals
Tunnel current signal J_tnThe digital tunnel current signal
J_tn(t) ”. ). Digital tunnel current signal J
_tn(t) is calculated by logarithmic conversion by the logarithmic conversion circuit 803.
Linearized with respect to the distance between the probe and the recording medium.
(Hereinafter, linearized digital tunnel current signal J
_tn(t) is converted to the “linearized digital tunnel current signal LogJ
_tn(t) ”. ). Linearized digital tunnel current signal
Issue LogJ_tn(t) is input to the positive input terminal of the subtractor 804
Then, the subtractor 804 sets a predetermined set value Z₀ Be subtracted from
Error signal e_nconverted to (t). PI control circuit 80
At 6, the error signal e_nselected so that (t) is zero.
Distance control signal that displaces the distance between the probe and the recording medium.
Issue U_n(t) is created. Distance control signal U_n(t) is D / A
After being converted into an analog signal by the converter 808, the switching circuit
Drives the selected probe in the Z-axis direction by 809
Applied to the actuator.

The probe head control circuit sequentially switches the probes to be selected, and all the probes 814 _{11 to} 814 _44.
In the same manner, control in the Z-axis direction is performed. At this time, the FB loop gain setting circuit (not shown) estimates the displacement reduction amount of each probe 814 _{11 to} 814 ₄₄ due to the contact,
The control parameters K _{11 to} K ₄₄ of the PI control circuit 806 for compensating the estimated displacement reduction amounts are created and stored in the memory 807. As a result, the PI control circuit _{806, U n (t) =} K p × e n (t) + K i × ∫e n (t) dt (4) However, K _p, the K _i = control parameter, distance control The signal U _n (t) is generated, but the control parameter K _i of the integral term (the second term of the same equation) of the above equation (4) is increased so as to compensate for the displacement decrease. As the control parameters K _i , the control parameters K _{11 to} K ₄₄ stored in the memory 807 are used.

In the present embodiment, the displacement reduction due to the contact is compensated by changing the control parameters K _i of the two items of the equation (4), but in the digital servo system as described above, the analog value is changed. It is also possible to increase the advantage of the integral term of the above equation (4) by increasing the clock frequency of the sampling timing that is converted into a digital value from the above.

[0069]

Since the present invention is configured as described above, it has the following effects.

(1) The deterioration of the distance control performance between the elastic probe and the sample caused by the decrease in the displacement of the tip of the conductive tip due to the contact of the tip of the elastic probe with the medium is compensated for. Stable control can be enabled. As a result, stable signal reproduction can be realized in a scanning tunneling microscope or recording / reproducing apparatus using a microprobe.

(2) In a scanning tunneling microscope or a recording / reproducing apparatus using a multi-probe head in which microprobes are integrated, variations in mechanical characteristics of a plurality of elastic body probes are absorbed, and when each elastic body probe makes contact with each other. It is possible to compensate for the deterioration of the probe position control performance due to the displacement reduction, and to realize stable signal reproduction from all the probes.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a scanning tunneling microscope of the present invention.

2A and 2B are diagrams showing a specific configuration of the elastic probe shown in FIG. 1, in which FIG. 2A is a side sectional view and FIG.
It is sectional drawing which follows the A line.

3 is a block diagram showing a configuration of a Z servo circuit shown in FIG.

4A and 4B are diagrams for explaining the FB loop gain setting circuit shown in FIG. 1, where FIG. 4A is a diagram showing a state in which a conductive tip and an observation sample are in contact with each other by an attraction force, and FIG.
Is a model representing the position of the base of the elastic probe, the position of the tip of the conductive tip and the position of the surface of the observation sample when the tip of the conductive tip contacts the coating layer on the surface of the observation sample in the initial state of contact. (C) is a model showing the position of the root of the elastic probe, the position of the tip of the conductive tip, and the positional relationship of the surface of the observation sample when the tip of the conductive tip is displaced by "ΔZ _S ". FIG.

5A and 5B are views for explaining the effect of a large decrease in the displacement of the tip of the conductive tip shown in FIG. 1 on the position control of the elastic probe, FIG. 5A being the Z axis of the elastic probe. FIG. 3B is a block diagram showing a control system normally used when performing directional position control, and FIG. 3B is a block diagram showing the control system when the displacement of the tip of the conductive tip is reduced.

FIG. 6 is a graph for explaining the effect of a large decrease in the displacement of the tip of the conductive tip shown in FIG. 1 on the position control of the elastic probe.

FIG. 7 is a schematic configuration diagram showing a first embodiment of a recording / reproducing apparatus of the present invention.

FIG. 8 is a diagram for explaining the configuration of the multi-probe head shown in FIG.

9 is a diagram for explaining the configuration of the Z servo circuit shown in FIG. 7. FIG.

FIG. 10 is a diagram for explaining the configuration of a Z servo circuit in the second embodiment of the recording / reproducing apparatus of the present invention.

[Explanation of symbols]

1 Observation Sample 10 Scanning Tunnel Microscope 11 XY Fine Motion Drive Mechanism 12 XY Fine Motion Drive Circuit 13 Bias Circuit 21 Current-Voltage Conversion Circuit 22 Logarithmic Conversion Circuit 23 Z Servo Circuit 24 Amplifier 25 Z Fine Motion Mechanism 26 FB Loop Gain Setting Circuit 30 Control Circuit 31 Switch circuit 32 Display 40 Elastic body probe 41 Silicon substrate 42 First SiNx layer 43 First drive electrode 44 First piezoelectric thin film 45 Second drive electrode 46 Second piezoelectric thin film 47 Third drive Electrode 48 Second SiNx layer 49 Conductive tip 50 Tip electrode 101 Subtractor 102 Variable gain amplifier 103 Low-pass filter 104 Correction circuit 201 Coating layer 301 to 305 Block 600 Recording / reproducing device 601 Recording medium 611 Structure 612 Base 613 Z actuator 614 Multi-probe head 614 _{11 to} 614 ₄₄ , 814 ₁₁ , 814 ₁₂ , 814 ₄₄ Probe 615 XY actuator 616 Probe head control circuit 617 Z servo circuit 618 FB loop gain setting circuit 619 Cantilever drive circuit 620 Tilt correction circuit 621 Voltage application circuit 622 Scan circuit 623 Tracking control circuit 624 Adder circuit 625 Sign 626 Decoder 701,801 Selection circuit 702,802 A / D conversion circuit 703,803 Logarithmic conversion circuit 704,804 Subtractor 705 Gain correction circuit 706,807 Memory 707,806 PI control circuit 708,808 D / A conversion circuit 709,809 Switching circuit k _P , k _S Elastic constant J _t Tunnel current V _t Voltage Log (V _t ) Logarithmic voltage P _G Gain parameter S _L Distance control signal Z ₀ Distance set value e Error signal S Correction distance control signal

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Toshimitsu Kawase 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Masahiro Tagawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Kya Non non corporation

Claims (10)

[Claims] 1. The position of the elastic probe is controlled by using a current flowing between the conductive tip and the sample when the conductive tip provided at the tip of the elastic probe is brought into contact with the sample. In the probe position control method described above, the displacement decrease of the tip of the elastic probe caused by the contact between the conductive tip and the sample is corrected. 2. The displacement reduction of the tip of the elastic probe is corrected by correcting the gain of a control loop for controlling the distance between the conductive tip and the sample. Item 1. A probe position control method according to item 1. 3. A sample comprising: a plurality of elastic probes having conductive tips provided at their tips, wherein the conductive tips of a multi-probe head are brought into contact with the sample. In the probe position control method for controlling the position of each elastic probe by using each current flowing in between, displacement of the tip of each elastic probe caused by contact between each conductive tip and the sample A probe position control method characterized by correcting each decrease. 4. Correcting the displacement reduction of the tip of each elastic probe by correcting the gain of each control loop for controlling the distance between each conductive tip and the sample. 4. The method according to claim 3,
The probe position control method described. 5. A multi-probe head in which a plurality of elastic probes having conductive tips provided at the tip are integrated, and the conductive tips and the sample when the conductive tips are brought into contact with a sample. In a scanning tunneling microscope including a plurality of control means for controlling the position of each elastic probe by using each current flowing between, a plurality of correction means for correcting the gain of the control loop of each control means. A scanning tunneling microscope, comprising: 6. The storage device according to claim 5, further comprising a storage unit that stores the correction amount of each correction unit.
The scanning tunneling microscope described. 7. The scanning tunneling microscope according to claim 5, further comprising storage means for storing feedback parameters of the respective control means. 8. A multi-probe head in which a plurality of elastic probes having conductive tips provided on the tip are integrated, and the conductive tips and the sample when the conductive tips are brought into contact with a sample. In a recording / reproducing apparatus provided with a plurality of control means for controlling the position of each elastic probe by using each current flowing between the plurality of control means, a plurality of control loop gains of the control means are respectively corrected. A recording / reproducing apparatus including a correction unit. 9. The storage device further includes a storage unit that stores the correction amount of each correction unit.
The recording / reproducing apparatus described. 10. The recording / reproducing apparatus according to claim 8, further comprising storage means for storing feedback parameters of the respective control means.