JPH05296710A - Inclination detecting method and device using the method - Google Patents

Abstract

PURPOSE:To detect an amount of inclination across a substrate using a plurality of electrodes. CONSTITUTION:Electrodes S1 to S6 are concentrically formed on the reverse side of a substrate 1 equipped with a probe head, and AC power supplies V1 to V6 are respectively connected thereto. The power supplies V1 to V6 generate voltage V1 to V6 respectively dephased with pi/3 (60 deg.) at the same angular frequency omega. A sample or a board 2 as recording media has a conductive electrode SS, and the electrodes S1 to S6 of the substrate 1 and the electrode SS form what is called a parallel plate capacitor. Electric current flowing to the electrode SS from the power supplies V1 to V6 via the electrodes S1 to S6 is detected with a load resistor RL as voltage output. The detected voltage Vd in this case is amplified by an amplifier 3 and, then, inputted to synchronous detectors 4 and 5. Furthermore, the detectors 4 and 5 synchronously detect voltage vector showing the X- and Y-axis directions of the probe head respectively as a reference signal. Then, the magnitude of the voltage vector detected at the board 2 in X- and Y-axis directions is detected as an inclination amount in respective directions.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inclination detecting method, an information processing apparatus using the same, a tunnel microscope and the like.

[0002]

2. Description of the Related Art In recent years, a scanning tunneling microscope (hereinafter referred to as STM) capable of directly observing the electronic structure of surface atoms of a conductor.
Was developed by [G. Binnig et al. Phys. Rev. Lett, 49, 57 (19
82)], single-crystal or amorphous, high-resolution measurement of real space images is possible.

The STM is a metallic probe (probe electrode)
The fact that a tunnel current flows when a voltage is applied between the conductive materials to bring them closer to a distance of about 1 nm is used. This current is very sensitive to changes in the distance between the two, and by scanning the probe so as to keep the tunnel current constant, it is possible to read various types of information regarding all electron clouds in real space. At this time, the resolution in the in-plane direction is about 0.1 nm.

A recording / reproducing apparatus using this STM is disclosed in, for example, Japanese Patent Laid-Open No. 61-80536. In this recording / reproducing apparatus, writing is performed by removing atomic particles adsorbed on the surface of the medium by an electron beam or the like. , STM is reproducing this data.

As a recording layer, a material having a memory effect with respect to switching characteristics of voltage and current, for example, a thin film layer of π-electron organic compound or chalcogen compound is used to record / record.
A method of reproducing by STM is disclosed in Japanese Patent Laid-Open No. 63-161552.
Japanese Patent Laid-Open No. 63-161553. According to this method, the recording bit size is 10n.
When m, a large capacity recording / reproducing of 10 ¹² bits / cm ² is possible.

Further, a device for forming a plurality of probe electrodes on a semiconductor substrate for the purpose of downsizing and displacing a recording medium facing the probe electrodes for recording is disclosed in JP-A-62-281138 and JP-A-1-196751. It is disclosed in the publication.

In these devices, probe electrodes for detecting a tunnel current are provided on a plurality of cantilevers formed by a semiconductor process, and a recording medium facing them is attached to a cylindrical piezoelectric element to cause circular motion. By doing so, recording and reproduction are performed.

When accessing a recording medium using a multi-probe array head having a plurality of probe electrodes, the probe head substrate and the recording medium substrate must be arranged in parallel. Normally, the distance between these two substrates is set to 1 to 3 μm. Further, the variation amount of the distance is required to be ± 0.5 μm or less.

For example, when a probe electrode is formed on a cantilever having a length of 300 μm and the cantilever is displaced in the vertical direction of the substrate by electrostatic force or piezoelectric power of a piezoelectric thin film, the maximum displacement amount is 3 to 10 μm. .. The tips of all the probe electrodes are arranged on the same plane, and in order to maintain the same probe electrode-substrate distance, the distance between the probe head substrate and the recording medium substrate is 3 μm or less within the movable range of the cantilever. At a distance of
In addition, it is necessary to set a distance that can compensate for a variation of about ± 1 μm in the warp caused by the manufacturing of each cantilever.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a tilt detecting method for detecting tilt between substrates using a plurality of electrodes, and an apparatus using the tilt detecting method.

[0011]

A tilt detecting method according to a first aspect of the present invention for attaining the above object comprises a relative tilt between a first substrate and a second substrate facing the first substrate. And a step of applying AC voltages having different phases to the plurality of electrodes provided on the first substrate, and a method of detecting the voltage on the second substrate facing the plurality of electrodes. The method is characterized by including a step of detecting a current flowing into the detection electrode from the plurality of electrodes by the detection electrode, and a step of measuring a phase and an amplitude of the detected current.

An information processing apparatus according to a second invention related to the first invention is an information processing apparatus for recording / reproducing / erasing by using a recording medium and a probe head approaching and facing the recording medium, A plurality of electrodes provided on the probe head, an oscillator for applying an alternating voltage having a different phase to each of the plurality of electrodes, a detection electrode provided on the recording medium facing the plurality of electrodes, and a detection electrode An inclination detection unit that detects the inclination between the recording medium and the probe head by measuring the phase and amplitude of the detected current; and a control mechanism that makes the inclination detected by the inclination detection unit zero. It is a feature.

The scanning probe microscope according to the third invention related to the first invention is a scanning probe microscope for observing the shape or electronic state of the surface of a sample by using a sample and a probe head which approaches and faces the sample. And a plurality of electrodes provided in the probe head, and an oscillator for applying an AC voltage having a different phase to each of the plurality of electrodes,
A detection electrode provided on the sample facing the plurality of electrodes, an inclination detection means for detecting the inclination between the sample and the probe head by measuring the phase and amplitude of the current detected by the detection electrode, And a control mechanism for making the inclination detected by the inclination detection means zero.

[0014]

In the tilt detecting method and the apparatus using the same having the above-described structure, alternating voltages having different phases are applied to the plurality of electrodes formed on the first substrate, and the plurality of electrodes form the second substrate. The amount of tilt is directly detected by detecting the current flowing into the device and further performing phase detection with a phase component containing the amount of tilt of the second substrate relative to the first substrate as information.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the principle of operation of the tilt detecting method of the present invention. Electrodes S1 to S6 are formed concentrically on the back surface of the substrate 1 having a probe head, and AC power sources V1 to V6 are connected to the electrodes S1 to S6, respectively. The power sources V1 to V6 have the same angular frequency ω, and the voltages V1 to V6 are out of phase by π / 3 (60 °).
To occur. That is, the voltages V1 to V6 applied to the electrodes S1 to S6
Generates a voltage vector that rotates on the surface of the substrate 1. The voltage Vn applied to the electrode Sn is expressed by the following equation. Vn = Vo · exp {i (ωt + (n-1) π / 3)}) (where n = 1, 2, 3, ... 6, and i ² = −
1)

The substrate 2 which is a sample or a recording medium has a conductive electrode SS, and the electrodes S1 to S6 of the substrate 1 and the electrode SS of the substrate 2 are provided.
Form a so-called parallel plate capacitor, and its capacitance Cn is, as shown by the following equation, the area So of the electrode Sn and the electrode SS.
It is decided by the distance dn between and. When ε _o is the permittivity in vacuum, the following equation is obtained. Cn ＝ ε _o・ So / dn

From the power sources V1 to V6 through the electrodes S1 to S6, the electrode SS
The current flowing into the load resistance RL is detected as a voltage output. The detection voltage Vd at this time is expressed by Vd = i · ω · RL · Σ n (Cn · Vn). This voltage Vd is amplified by the amplifier 3 and then input to the synchronous detectors 4 and 5.

The synchronous detectors 4 and 5 are voltage vectors indicating the X-axis and Y-axis directions of the probe head, respectively (since the current flowing through the capacitance Cn leads the voltage Vn by π / 2 in phase,
Synchronous detection is performed by using an AC voltage having an angular frequency ω and a phase of −π / 2 and 0) as a reference signal. That is, the magnitude of the voltage vector in the X-axis direction and the voltage vector in the Y-axis direction detected on the substrate 2 is detected as the amount of tilt in each axial direction. At this time, the inclination amount Xc is detected, Yc is, Xc = π · A · Σ n (cos [(n-1) π / 3} / dn) Yc = π · A · Σ n (sin [(n- 1) π / 3} / dn) (However, A = ε _o · So · Vo · RL) (1)

When the inclinations of the substrate 1 in the X and Y directions are α and β, respectively, and the coordinate radii of the electrodes S1 to S6 arranged concentrically are r, the distance dn is the inclinations α and β and the average substrate. It can be expressed by the following equation by the distance do. dn = α ・ r ・ cos [(n-1) π / 3} + β ・ r ・ sin [(n-1) π / 3} + do

Furthermore, 1 / dn = 1 / ( do + Δdn) = 1 / do-Δdn / do 2 + (Δdn) 2 / do 3 - ··· and expand, under the conditions of Derutadn«do, until the second term Taking 1 / dn = 1 / do−α · r · cos [(n−1) π / 3} / do ² −β · r · sin [(n−1) π / 3} / do ² ·· Since (2), the inclination amounts Xc and Yc are Δdn << when the average inter-substrate distance do is sufficiently smaller than the distance between the electrodes S1 to S6.
do holds and substituting Eq. (2) into Eq. (1), Xc = (π · A · r / 2do ² ) · α Yc = (π · A · r / 2do ² ) · β.

Here, the inclination amounts Xc and Yc represent the inclinations α and β in the directions defined at the beginning. In this case, the directions of Xc and Yc do not have to be orthogonal to each other and can be aligned with the drive axis of the mechanism for tilting the substrate 1 having the probe head. Further, the minimum number of axes that determine the probe head surface is 2, but even if there are two or more drive axis directions, the inclination in each axis direction can be detected. According to such a method, it becomes possible to easily control the parallel plane holding without performing complicated calculation processing.

FIG. 2 is a plan view of an embodiment in which the tilt detecting mechanism is applied to an STM device, FIG. 3 is a front view, and FIG. 4 is a side view. The sample table 1 on which the observation sample S is arranged is mounted on the support table 10.
1, an XY scanning drive mechanism 12 for scanning in the XY plane, and a Z direction drive mechanism 1 for moving the support substrate 13 in the Z direction.
4 and are installed. Here, the observation sample S is electrically conductive and also serves as the electrode SS described above. Probe head substrate 1 having probe electrodes formed on a cantilever
The probe head substrate 5 is supported by the support substrate 13. The electrodes S1 to S6 described above are provided on the periphery of the probe head substrate 15. Further, the Z-direction drive mechanism 14 supports the support substrate 13 via four piezo elements 16, a sharpened portion 17 attached to the piezo elements 16, and a tension spring 18 so that the amount of inclination thereof can be adjusted.

FIG. 5 shows the electrode S1 on the probe head substrate 15.
In the signal processing circuit unit 19, a tunnel current signal detected by a plurality of probe electrodes formed on the probe head substrate 15 is processed and output to an external circuit. An AC voltage whose phase is rotated by π / 3 is applied to each of the electrodes S1 to S6. In this embodiment, by utilizing the fact that the probe head substrate 15 is a Si substrate, these AC voltage generating circuits are integrally formed on the probe head substrate 15.

FIG. 6 shows a block circuit configuration diagram of the STM. The piezo element 16 for tilt correction attached to the Z-direction drive mechanism 14 supports the support substrate 13 from the back surface via the sharpened portion 17, and supports the support substrate. A plurality of cantilevers 22 having a probe electrode 21 at the tip are formed in the center of the surface of a probe head substrate 15 fixed to the surface of the surface 13, and electrodes S1 to S6 for tilt detection are provided in the peripheral portion of the surface. Drive electrodes 23 are provided. The observation sample S facing the probe head substrate 15 is a counter electrode of the electrodes S1 to S6.
It becomes SS and is fixed on the surface of the sample table 11, and the load resistance
It is connected to the RL and the inclination correction control circuit 24. The output of the inclination correction control circuit 24 is connected to the piezo element 16 via the buffer circuit 25, and is also input to the approach control circuit 26 as it is.

In the drawing, the circuits 27 to 31 are shown to be attached to only one probe electrode, but in reality, these circuits are similarly attached to each probe electrode. Each probe electrode 21 on the probe head substrate 15 is connected to the input of each current amplifier 27, and the output of each current amplifier 27 is the positive input of each difference amplifier 28, the common image display circuit 29, and the common proximity control circuit 26. Connected to the input of. The negative input of each difference amplifier 28 is the reference voltage.
It is connected to Vr and its output is connected to the image display circuit 29 common to the Z-direction drive electrode of each cantilever 22 via each PID control circuit 30. The output of the approach control circuit 26 is connected to the Z-direction drive mechanism 14. Furthermore, X
The output of the Y scanning circuit 31 is the image display circuit 29 and the sample table 11.
Is connected to the XY scanning drive mechanism 12 shown in FIGS. In addition, a control CPU that controls these
32 is connected to these.

FIG. 7 shows an AC voltage generating circuit, in which an even number of CMOS inverters 41 are connected in a ring shape and a delay capacitor 42 is connected to every other CMOS inverter to form a so-called ring counter oscillation circuit. The number of connection stages of the inverter 41 and the size of the delay capacitor 42 are set so that a desired oscillation frequency can be obtained, and in FIG. 7, for convenience of description, the inverter 41 is composed of 12 inverters 41. The electrodes S1 to S6 extract voltages from the tap positions of the oscillator circuit which are symmetrical with respect to six times and are amplified by the buffer circuit 43. Further, the signals Vx and Vy for detecting the inclination amount are respectively taken out from the tap having a voltage advanced by π / 2 from the voltage of the electrode and the tap having the same phase as the electrode.

FIG. 8 is a block circuit diagram of the inclination correction control circuit 24. The observation sample S having conductivity is biased for STM via a load resistor RL for inclination detection.
The voltage connected to Vb and generated in the load resistance RL is amplified by the amplifier 44 and then connected to the synchronous detectors 45 and 46. The signals Vx and Vy shown in FIG. 7 are input as synchronous signals to the synchronous detectors 45 and 46, respectively, and detection is performed based on this phase. Outputs of the synchronous detectors 45 and 46 are input to arithmetic processing circuits 47 and 48 for feedback control. The arithmetic processing circuits 47 and 48 are for controlling while maintaining the stability of the system of the feedback loop. For example, a general PID control or a forward control that a priori calculates the control amount from the detected tilt amount. , A method such as control applying fuzzy theory is applied. The simplest is the arithmetic processing circuit 4.
Proportional control in which 7, 48 are simple amplifiers may be used.

The two tilt control amounts calculated by the arithmetic processing circuits 47 and 48 are input to four differential amplifiers 49, and four tilt adjustment amounts are adjusted by the difference or the sum and the inversion of the sign thereof. Are converted into respective driving voltages of the piezo elements 16. That is, when changing the tilt in the X direction, the piezo elements 16a and 16d shown in FIG. 4 are expanded and contracted in the same direction, and the piezo elements 16b and 16c are piezo elements 16a and 1d.
It expands and contracts in the same direction as 6d. When changing the inclination in the Y direction, set the piezo elements 16a and 16b in the same direction,
The piezo elements 16c and 16d are replaced by piezo elements 16a and 1
6b expands and contracts in the same direction as the opposite direction.

FIG. 9 shows a circuit example of the synchronous detection circuits 45 and 46. The amplifier 50 to which the input is connected has both positive and negative polarities, and the positive and negative outputs are analog switch SW1.
, SW2, and is input to the integrating circuit consisting of the resistor Ri and the capacitor Ci. The phase reference signal Vin is connected to the control input of the analog switch SW1 after being amplified and waveform-shaped, and its inverted signal is connected to the control input of the analog switch SW2. With this circuit configuration, the phase reference signal
The output voltage of the integration circuit is generated and output only with the signal that has the same phase component as Vin. The phase reference signal Vin is the signal Vx in the synchronous detection circuit 45, and the synchronous detection circuit 46
Then it is signal Vy.

Next, the approaching operation of the probe head and the sample substrate will be described. The tilt correction control circuit 24 detects the tilt amount based on the voltage detected by the load resistance RL, and the calculated driving voltage drives the tilt correction piezo element 16 via the buffer circuit 25. By controlling this circuit loop,
The sample S and the probe head substrate 15 are kept parallel to each other. The tunnel current flowing between the sample S and the probe electrode 21 by the bias power supply Vb is converted into a voltage by the current amplifier 27 and input to the differential amplifier 28. Differential amplifier 28
Compares the value of the tunnel current with the reference voltage Vr and amplifies the difference voltage. The PID control circuit 30 outputs a signal to change the displacement amount of the cantilever 22 in the Z direction so that the difference voltage becomes zero.

Further, the output of the tilt detection is monitored, and while confirming that the sample S and the probe head substrate 15 are parallel to each other, the Z-direction drive mechanism 14 is driven to bring the probe head substrate 15 close to the sample S. This operation is controlled by the approach control circuit 26 and is performed until a tunnel current flows through the probe electrode 21. When the tunnel current is detected from all the probe electrodes 21 on the probe head substrate 15, the STM is in a state where the surface of the sample S can be observed.

In the observation operation of the STM, the amount of change of the cantilever 22 is feedback-controlled so that the tunnel current is always a constant value, and the drive voltage of the cantilever 22 at this time is imaged into a topographic image by the image display circuit 29. .. Alternatively, the cantilever 22 is controlled so that the average value of the tunnel current is constant, and only the high frequency component of the tunnel current is imaged by the image display circuit 29 into a constant height image. A series of operations such as two-dimensional scanning of the XY stage of the sample table 11 by the XY scanning circuit 31 are sequence-controlled by the control CPU 32. Further, in FIG. 6, the STM image observing operation has been described with respect to only one probe electrode 21, but in practice, similar processing may be performed in parallel on tunnel currents from a plurality of probe electrodes 21. For example, the images may be displayed simultaneously by switching in a time-division manner.

As described above, by applying the tilt detecting method according to the present invention to the STM using the plurality of probe electrodes 21, the probe head can easily approach the sample S and the region to be observed of the sample is searched. Time can be shortened. Further, the unevenness of the contrast on the image caused by the inclination between the observation sample S and the probe head is eliminated.

Next, the recording / reproducing apparatus according to the present invention will be described. 10 is a plan view and FIG. 11 is a front view. The piezo element 16 attached to the support 10 has a sharpened portion 17
The XYZ drive mechanism 62 supports the support base 61 via the recording medium substrate R fixed to the recording medium support base 63.
Are arranged so as to be driven in the three axis directions. The support base 61 of the probe head substrate 15 includes piezo elements 16a, 1
Positioning is performed at three points by a sharpened portion 17 attached to 6b and abutting on the back surface, and a fulcrum P3 fixed on the support base 10 and abutting on the front surface.

That is, as shown in FIG. 12, the support base 61 is fixed at three points of the contact points P1 and P2 of the pointed portion 17 driven by the piezo elements 16a and 16b and the fulcrum P3, and the piezo elements 16a and 16b are fixed. By expanding and contracting, the tilt can be changed with respect to the two axes having an angle of 60 degrees with respect to the fulcrum P3. Then, a cantilever forming portion 64 is provided in the center of the probe head substrate 15, and an electrode (SS electrode) 65 for tilt detection is formed around the cantilever forming portion 64.

FIG. 13 is a view showing the arrangement of tilt detection drive electrodes 70 on the recording medium substrate R and the configuration of the drive circuit. A recording layer 71 is provided in the center of the recording medium substrate R, and an inclination detecting drive electrode 70 composed of S1 to S4 is provided outside the recording layer 71. That is, the electrodes S1 to S4 are arranged at the respective vertices of the square, and the signals of which the phases are shifted by π / 2 are supplied from the oscillator of the ring counter composed of the plurality of inverters 72 via the buffer amplifier 73. Further, signals .phi.1 and .phi.2 obtained by advancing the phases of the phase signals in the directions corresponding to the two drive axes forming an angle of 60.degree. By .pi. / 2 are taken out from this oscillator for the inclination detection processing described later. At this time, in order to compensate for the phase shift due to its own electrostatic capacity of the drive electrode, the amplifier 75 outputs the compensation capacitor 74 in parallel.

FIG. 14 is a block circuit diagram of the recording / reproducing apparatus. The probe head substrate 15, which is variably supported by the two piezo elements 16 and the fulcrum P3 with respect to the inclination about the two axes, faces the recording medium substrate R movably supported by the XYZ drive mechanism 62 in the three axis directions, The probe electrode 2 at the tip of the cantilever 22 on the substrate 15
1 and the recording layer 71 of the recording medium substrate R are close to each other, and the electrode 65 on the probe head substrate 15 and the drive electrode 70 of the recording medium substrate R face each other. After the voltage of the load resistance RL connected to the electrode 65 (that is, the electrode SS) is amplified by the amplifier 44, it is input to the synchronous detectors 45 and 46, the outputs of which are output via the arithmetic processing circuits 47 and 48, respectively. It is output to the piezo elements 16a and 16b, respectively.

A current amplifier 27 is connected to each probe electrode 21 via a resistor Rx and a bias power supply Vb. The output of the current amplifier 27 is connected to the positive input of the differential amplifier 28 and the reference voltage Vr is connected to the negative input. , The output of the differential amplifier 28 is P
Each cantilever 2 via the ID control amplifier 30.
2 is connected to the drive electrode in the Z direction.

The signals φ1 and φ2 output from the amplifier 75 of the recording medium substrate R are connected to the phase reference inputs of the synchronous detectors 45 and 46, respectively, and the magnitude of the drive current of the arithmetic processing circuit 48 is the proximity control circuit. 26 is transmitted. The approach control circuit 26 is also connected to the output of the current amplifier 27 and the output of the arithmetic processing circuit 47, and the output is connected to the XYZ drive mechanism 62. The output of the XY scanning amplifier 31 is connected to the XY driving signal input of the XYZ driving mechanism 62.

The output of the modulation circuit 76 is connected to the probe electrode 21 via a capacitor Cx, and data is input to the input of the modulation circuit 76 from the outside. The output of the current amplifier 27 is connected to the input of the demodulation circuit 77, and the demodulation circuit 77 outputs data to the outside.

Although not shown in FIG. 14, a data reading circuit and a data writing circuit are provided for each probe electrode.

Probe head substrate 15 and recording medium substrate R
The approaching operation with and is performed in the same manner as the STM described above. That is,
The signal detected by the load resistor RL is amplified by the amplifier 44 and input to the synchronous detectors 45 and 46. The reference signals .phi.1 and .phi.2 for this synchronous detection have a phase difference of 60.degree., And tilt components along the drive axes of the piezo elements 16a and 16b are detected.

The detection signals output from the synchronous detectors 45 and 46 are fed back to the arithmetic processing circuit 4 for feedback.
The piezo elements 16a, 16b are driven via 7, 48. The configurations of the arithmetic processing circuits 47 and 48 do not need to consider the inclinations of the mutual axes, and may be set so that the respective feedback control is stable. Specifically, P
ID control or simple proportional control may be used. Of course, by using fuzzy control or the like, the approach speed between the recording medium and the probe head, the distance from the probe head, the amount of inclination of the probe head, the distribution tendency of the variation of the cantilever 22 warp in the probe head surface, and the drive mechanism Needless to say, further stable control can be performed by organically utilizing and controlling the parameters such as the inertial amount.

The approach control circuit 26 is the probe head substrate 1
The approaching operation is performed while monitoring the amount of inclination between the recording medium substrate R and the recording medium substrate 5 and the distance. The distance between the probe head substrate 15 and the recording medium substrate R is equal to that of the drive electrode 7 provided on the recording medium substrate R.
It can be calculated by obtaining the total amount of current flowing from 0 to the detection electrode 65 of the probe head substrate 15. In this embodiment, the distance between the substrates is measured by the current supplied to the arithmetic processing circuit 48 that drives the drive electrode 70.

The approach control circuit 26 is the probe head substrate 1
When the distance between the probe head substrate 15 and the recording medium substrate R reaches, for example, 3 μm, the tunnel current of each probe electrode 21 is changed. To check. At this time, if all the probe electrodes 21 do not detect the tunnel current, the approaching speed is reduced and the approaching is continued. After all the probe electrodes 21 detect the tunnel current,
This Z-direction approaching operation is completed.

Cantilever 2 depending on the probe head
The warp distribution of 2 may be inclined in one direction. In such a case, when the probe electrode 21 of the probe head substrate 15 partially detects the tunnel current, the distribution state thereof may be calculated and corrected.

In the recording / reproducing apparatus of the present invention, since the distance between the probe head and the recording medium can be measured independently of the detection of the tunnel current of the probe electrode 21, the warp distribution of these cantilevers 22 can be easily calculated. it can.

Next, the recording / reproducing operation of the recording / reproducing apparatus of the present invention will be described. From probe electrode to current amplifier 27
The tunnel current value which is amplified by and converted into a voltage is compared with the reference voltage Vr by the differential amplifier 28, and the PID control amplifier 30 displaces the cantilever 22 in the Z direction so that the average of the comparison value becomes zero. Is adjusted. That is, by this operation, the distance between the probe electrode and the medium is controlled to be constant. This operation is performed for each cantilever 22 on the probe head substrate 15.
In this state, the XY drive mechanism 62 scans the medium XY. At this time, the information written in the recording medium layer as a change in physical state is read by the probe electrode 21 as a change in tunnel current. This tunnel current is input to the demodulation circuit 77 after being amplified by the current amplifier 27 that performs current-voltage conversion. The demodulation circuit 77 restores the read signal to a digital data format and outputs it.

When the data writing operation is performed, the modulation circuit 76 is controlled while the cantilever 22 is controlled so that the distance between the probe electrode and the medium is constant as in the reproducing operation.
Converts the input data into the write voltage by
It is applied to the probe electrode 21 via Cx.

As described above, by applying the tilt detecting mechanism of the present invention to the recording / reproducing apparatus, the probe head substrate 1
5 when approaching the recording medium substrate R, the probe electrode 21
Is prevented from colliding with the recording layer 71, and damage to recorded data and deterioration of the probe electrode 21 are prevented.

Further, the AC voltage applied for detecting the inclination cancels each other out when the probe head substrate 15 and the recording medium supporting base 63 are held in parallel with each other, and may not be mixed into the probe current as noise during recording and reproduction. Absent.

[0052]

As described above, the tilt detecting method according to the present invention and the processing apparatus using the same can detect the amount of substrate tilt in any direction. That is, by making the detected inclination direction coincide with the drive axis of the substrate inclination correction mechanism, it is possible to easily perform parallel plane holding control by feedback control without performing complicated calculation.

Further, by using the tilt detecting method of the present invention, the tilt amount between the probe head substrate and the sample substrate can be detected from the state where the probe electrode is completely separated from the sample or the recording medium. That is, the parallelism between the substrates can be maintained before the probe electrode enters the region where the tunnel current can be detected, which has the following advantages.

(1) The probe head can be approached at high speed without the probe electrode colliding with the recording medium.

(2) Since the distance between the probe head and the recording medium can be measured, an appropriate distance between the probe head and the recording medium can always be maintained.

(3) The probe head retracting operation and access preparation operation can be realized by a simple control circuit, and the reliability of the apparatus is improved.

[Brief description of drawings]

FIG. 1 is a diagram illustrating the principle of tilt detection.

FIG. 2 is a plan view of an STM.

FIG. 3 is a front view of an STM.

FIG. 4 is a side view of the STM.

FIG. 5 is a layout view of tilt detection electrodes on a probe head substrate.

FIG. 6 is a block circuit configuration diagram of an STM.

FIG. 7 is a drive circuit diagram of an electrode for tilt detection.

FIG. 8 is a block circuit configuration diagram of a tilt correction control circuit.

FIG. 9 is a circuit diagram of a synchronous detection circuit.

FIG. 10 is a plan view of a recording / reproducing apparatus.

FIG. 11 is a front view of the recording / reproducing apparatus.

FIG. 12 is an explanatory diagram of a relationship between a probe head and a drive shaft of a tilt correction mechanism.

FIG. 13 is a drive circuit diagram of drive electrodes for tilt detection.

FIG. 14 is a block circuit configuration diagram of a recording / reproducing apparatus.

[Explanation of symbols]

 1, 2 Substrate 3 Amplifier 4, 5 Synchronous detector 10 Support stage 11 Sample stage 12 XY scanning drive mechanism 13 Support substrate 14 Z direction drive mechanism 15 Probe head substrate 16 Piezo element 17 Pointed tip 21 Probe electrode 22 Cantilever 23 Drive electrode 24 Tilt control circuit 26 Approach control circuit 29 Image display circuit 32 CPU S Sample R Recording medium substrate

 ─────────────────────────────────────────────────── (72) Inventor Akihiko Yamano 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Shunichi Shito 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Within the corporation

Claims (4)

[Claims] 1. A method for detecting a relative inclination between a first substrate and a second substrate facing the first substrate, wherein the plurality of electrodes provided on the first substrate are different from each other. Applying an alternating voltage having a phase, detecting a current flowing from the plurality of electrodes to the detection electrode by a detection electrode facing the plurality of electrodes and provided on the second substrate, and the detection And a step of measuring the phase and amplitude of the generated current. 2. An information processing apparatus for recording / reproducing / erasing by using a recording medium and a probe head which approaches the recording medium and faces the recording medium, wherein a plurality of electrodes included in the probe head and the plurality of electrodes are provided. Oscillators for applying alternating voltage having different phases to each other, detection electrodes provided on the recording medium facing the plurality of electrodes, and the recording by measuring the phase and amplitude of the current detected by the detection electrodes. An information processing apparatus comprising: an inclination detection unit that detects an inclination between a medium and a probe head; and a control mechanism that makes the inclination detected by the inclination detection unit zero. 3. A scanning probe microscope for observing the shape or electronic state of a sample surface by using a sample and a probe head that approaches and opposes the sample, and a plurality of electrodes provided on the probe head, and a plurality of electrodes. An oscillator for applying alternating voltage having different phases to the electrodes of the electrodes, a detection electrode provided on the sample facing the plurality of electrodes, and a phase and an amplitude of a current detected by the detection electrodes. A scanning probe microscope comprising: an inclination detecting means for detecting the inclination between the sample and the probe head; and a control mechanism for making the inclination detected by the inclination detecting means zero. 4. The apparatus according to claim 2, wherein the probe head is a multi-probe array head having a plurality of probes.