JPH06195776A - Recording/reproducing method and device - Google Patents

Abstract

PURPOSE:To prevent a recording error from occurring in a recording/ reproducing method and a device therefor. CONSTITUTION:When a probe 11 scans in the +X-axis direction as a distance between the probe 11 and a recording layer 13 is kept at a fixed value in a recording and reproducing device 10, a control signal C is transmitted over an offet generating circuit 21 from a write timing circuit 18, and offset voltage VOF is output from the offset generating circuit 21 to a drive circuit 17. A piezo actuator 21 is driven by a drive signal SD prepared by the drive circuit 17 corresponding to voltage, in which offset voltage VOF is overlapped to drive voltage VD, thus moving the probe 11 in the -Z-axis direction until the probe II is brought into contact molecularly with the recording layer 13. A recording bit 14 is formed at the said position of recording of the recording layer 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording / reproducing method and a recording / reproducing apparatus, and more particularly to recording recording information on a recording medium using a signal generated by a physical interaction between a recording medium and a probe. The present invention relates to a recording / reproducing method and a recording / reproducing apparatus for reproducing the recorded record information.

[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 is expected to have a wide range of applications for the following reasons (G. Binnig et al. , Phys. Rev. Lett., 49, 57, 19
82). (1) Real-space images can be measured with extremely high resolution (nanometer or less) regardless of whether they are single crystals or amorphous. (2) It has an advantage that it can be observed at low power without damaging the sample by current. (3) It operates in the atmosphere and can be used for various materials.

A scanning tunneling microscope is used as a probe when a probe (metal probe) and a conductive substance are applied with a voltage and the probe is brought close to the surface of the conductive substance by a distance of about 1 nm. The tunnel current flowing between the conductive material and the surface of the conductive material is used. The magnitude of this tunneling current depends on the distance between the probe and the surface of the conductive material and is very sensitive to changes in this distance. Therefore, by scanning the probe so as to keep the magnitude of the tunnel current constant, it becomes possible to read various kinds of information regarding the whole electron cloud in the real space. Also,
The analysis using the scanning tunneling microscope is not limited to the surface analysis of the conductive material, but is beginning to be applied to the structural analysis of the insulating film thinly formed on the surface of the conductive material. In any case, the in-plane resolution of the conductive material or the insulating film is about 0.1 nm.

If the principle of such a scanning tunneling microscope is applied, the atomic order (sub-nanometer) can be sufficiently obtained.
It is possible to perform high-density recording / reproduction in. That is, it is possible to record the recorded information by physically deforming it or changing the electronic state of the surface of the recording medium on the recording medium, and it is possible to reproduce the recorded recording information by the scanning tunneling microscope. For example, a pulse voltage (for example, a peak value of 3 to 8) is applied between the recording medium and the probe.
By applying V and a pulse voltage having a pulse width of 1 to 100 μs, when graphite is used as the recording medium, minute holes (for example, minute holes having a diameter of about 4 nm) can be formed on the surface of the graphite.
When a metal such as Au is used as the recording medium, it is known that minute protrusions (for example, minute protrusions having a diameter of about 10 nm) can be formed on the surface of the metal, and such minute holes and minute protrusions are used as recording bits. Can be used.

Further, as the recording layer, a material having a memory effect on the switching characteristic of the change in conductivity (for example,
A method of performing recording / reproduction with a scanning tunneling microscope using a thin film layer of a π-electron organic compound or chalcogen compound is disclosed in JP-A-63-161552 and JP-A-6-165552.
It is disclosed in Japanese Patent Publication No. 3-161553. According to this method, if the recording bit size is 10 nm, then 10
Large-capacity recording / playback of ¹² bit / cm ² is possible.

In the recording / reproducing apparatus applying the principle of the scanning tunneling microscope, when recording the recording information on the recording medium, the probe is kept waiting for the probe to reach a predetermined position, or while the probe is being scanned. After stopping the scanning of, the operation of increasing the tunnel current flowing between the probe and the recording medium is performed. Here, in order to increase the tunnel current, generally, the applied bias voltage may be gradually or sharply changed, but the recording time is shortened and the influence of disturbance such as temperature drift and vibration is increased. In order to suppress the noise, it is preferable to apply a pulsed voltage between the recording medium and the probe.
A pulse voltage of -10 V and a pulse width of 0.1-100 μs is applied.

[0007]

However, in the recording / reproducing apparatus to which the principle of the scanning tunneling microscope described above is applied, the electric field strength between the recording medium and the probe also increases as a result of increasing the applied voltage during recording. . That is, assuming that the distance between the recording medium and the probe is about 1 nm, the electric field generated between the recording medium and the probe reaches 10 ⁷ to 10 ⁸ V / cm. Under such a strong electric field, a current mainly due to field emission flows. In this case, unlike the tunnel current, carrier injection may occur not only from the tipmost atom of the probe but from the sharp tip near the tip of the probe or the tip of the convex portion on the recording medium side. As a result, in some cases, the generation rate of recording bits decreases. Further, even when the recording bit is formed, the recording / reproducing position (recording bit formation target position) accessed in the tunnel current mode and the portion where the tunnel current flows during recording (actual recording bit formation position) are displaced, The shape of the recording bit may be distorted or the recording bit may be enlarged.

In a large-capacity recording / reproducing apparatus, the problem of recording error causes the recording / reproducing process to be complicated, and
The increase in recording redundancy causes a decrease in recording density. As a result, the entire system becomes complicated and large.

It is an object of the present invention to provide a recording / reproducing method and a recording / reproducing apparatus capable of preventing a recording error.

[0010]

In the recording / reproducing method of the present invention, recording information is recorded on the recording medium by using a signal generated by a physical interaction between the recording medium and the probe. In the recording / reproducing method of reproducing recorded information, the probe is brought into molecular contact with the recording medium during a period of recording the recorded information.

Here, the contact resistance value between the recording medium and the probe when the probe is brought into molecular contact with the recording medium may be 1 MΩ or less, and the probe is brought into molecular contact with the recording medium. The contact resistance value between the recording medium and the probe at this time may be 100 kΩ or less.

Further, during the period in which the probe is brought into molecular contact with the recording medium, the recording medium and the probe are moved to such an extent that an acting force of 10 ⁻⁸ N or more is generated between the recording medium and the probe. The recording medium and the probe may be brought close to each other to such an extent that an action force of 10 ⁻⁷ N or more is generated between the recording medium and the probe during the period in which the probe is brought into molecular contact with the recording medium. May approach.

Further, when the distance between the recording medium and the probe in a period other than the period for recording the recording information on the recording medium is Z ₀ nm, during the period for recording the recording information on the recording medium, The recording medium and the probe may be brought closer to each other by (Z ₀ −4) nm or more, and during the period in which the recording information is recorded on the recording medium, the recording medium and the probe are set to Z ₀ nm or more (Z ₀ nm or more (Z ₀ +3) You may make it approach only by nm or less.

The recording / reproducing apparatus of the present invention records the recording information on the recording medium using a signal generated by the physical interaction between the recording medium and the probe, and reproduces the recorded recording information. The reproducing apparatus includes probe moving means for moving the probe in a direction perpendicular to the surface of the recording medium, and driving means for driving the probe moving means, the driving means including the recorded information on the recording medium. In the recording period, the probe moving means is driven to bring the probe into molecular contact with the recording medium.

Here, a current limiting means may be further included for limiting a current flowing between the recording medium and the probe to 1 μA or less when the probe is brought into molecular contact with the recording medium. However, it may be a resistance element provided in the current path, and the resistance value of the resistance element may be 1 MΩ or less.

[0016]

The recording / reproducing method and recording / reproducing apparatus of the present invention are
There is a marked difference in the degree of contact with the contact recording method using a known probe. That is, the contact in the recording / reproducing method and the recording / reproducing apparatus of the present invention is a state (atomic contact or molecular contact) in which only the minute region at the tip of the probe is in contact with the recording medium. In addition, since this contact is a contact at the most advanced atom, most advanced molecule, or molecular aggregate size, in the present specification, such contact is referred to as “molecular contact” for convenience.

The degree of molecular contact can be monitored by the value of current or resistance flowing in the state of being in molecular contact or the acting force (contact pressure) generated between the probe and the recording medium. Further, it is easy to control the distance between the probe and the recording medium on the order of sub-nanometers (for example, servo control of the probe position using a piezoelectric body) by a known scanning tunneling microscope technique. It is also possible to reproducibly achieve a desired molecular contact state by bringing the probe close to the recording medium by a certain amount from the state.

[0018]

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

FIG. 1 is a block diagram showing a first embodiment of the recording / reproducing apparatus of the present invention.

The recording / reproducing apparatus 10 includes a probe 11, a piezo actuator 12, an XY stage 13, a current / voltage conversion circuit 14, a sample / hold circuit 15, a servo circuit 16, a drive circuit 17, and a write timing circuit 18. , Bias generating circuit 19, XY scanning circuit 20, offset generating circuit 21, and data modulating circuit 2
2 and a data demodulation circuit 23.

The recording medium 1 is made of a material having a substrate 1 _1, and the base electrode 1 ₂ formed on the surface of the substrate 1 _1, which is formed on the base electrode 1 _second surface, a memory effect with respect to switching characteristics of the current-voltage It is composed of a recording layer 1 ₃ made of. Specifically, the recording medium 1, using a flat substrate such as a silicon substrate or a glass or mica as the substrate 1 _1,
Also used monocrystalline gold (Au) as the base electrode 1 _2. Furthermore, the recording medium 1 is

[0022]

[Chemical 1] Of polyamic acid molecule (molecular weight about 200,000)

[0023]

[Chemical 2] The hexadecylamine salt monomolecular film represented by the formula ( ₂ ) was formed by accumulating two, four or six layers on the base electrode 12 by the LB method, and then performing a heat treatment at 300 ° C. for 10 minutes for imidization.

[0024]

[Chemical 3] And a polyimide monomolecular film shown in using as the recording layer 1 _3.

Next, each component of the recording / reproducing apparatus 10 will be described in detail.

(1) Probe 11 and piezo actuator 12 The piezo actuator 12 is driven by the drive signal S _D sent from the drive circuit 17, and moves the probe 11 in the Z-axis direction in the drawing in response to the drive signal S _D. Let

(2) XY stage 13 The XY stage 13 is driven by the output signal of the XY scanning circuit 20 and is moved in the X-axis direction and the Y-axis direction in the figure in accordance with the output signal. The recording medium 1 is placed on the XY stage 13.

(3) Current-voltage conversion circuit 14, sample-hold circuit 15, servo circuit 16 and drive circuit 1
7 current-voltage conversion circuit 14 converts detects a current J flowing between the probe 11 and the base electrode 1 ₂ through the recording layer 1 ₃ into a voltage signal V. The sample hold circuit 15 holds the voltage value of the voltage signal V sent from the current-voltage conversion circuit 14 in response to the _first write control signal W ₁ sent from the write timing circuit 18. The servo circuit 16 calculates the drive voltage V _D by performing a predetermined calculation using the voltage value of the voltage signal V sent from the sample hold circuit 15. The drive circuit 17 is
A drive signal S _D is created according to the drive voltage V _D sent from the servo circuit 16 and the offset voltage V _OF sent from the offset generation circuit 21, and the created drive signal S _D is output to the piezo actuator 12. .

(4) Write Timing Circuit 18 and Offset Generation Circuit 21 The write timing circuit 18 generates the control signal C during recording. Offset generating circuit 21, the control signal C is the transmitted from the write timing circuit 18, and outputs an offset voltage V _OF for causing molecules contacting the probe 11 to the recording layer 1 _3.

(5) Bias Generating Circuit 19 and XY Scanning Circuit 20 The bias generating circuit 19 responds to the _second write control signal W ₂ sent from the write timing circuit 18 to read bias voltage V _BR and recording pulse voltage. generates a V _PW, is applied to the base electrode 1 _second recording medium 1. The XY scanning circuit 20 drives the XY stage 13 in response to the third write control signal W ₃ sent from the write timing circuit 18, and controls the probe 11 to trace the recording data string of the recording medium 1. To do.

(6) Data Modulation Circuit 22 and Data Demodulation Circuit 23 The data modulation circuit 22 modulates the recording data D sent from the outside and outputs it to the write timing circuit 18. Data demodulation circuit 23 demodulates the recorded data D recorded on the recording layer 1 ₃ of the recording medium 1 from the voltage signal V sent from the current-voltage conversion circuit 14, and outputs to the outside.

Next, regarding the operation of the recording / reproducing apparatus 10,
This will be described with reference to FIGS. 1 and 2.

The piezo actuator 21 is driven by the drive signal S _D generated by the drive circuit 17 in accordance with the drive voltage V _D sent from the servo circuit 16, and the XY stage 13 outputs the output signal of the XY scanning circuit 20. by being driven by, as shown in FIG. 2 (a), while the distance between the probe 11 and the recording layer 1 ₃ is kept at a constant value Z _0, the probe 11 is shown arrow direction (+ X-axis direction ) And is moved to a predetermined recording position. Then, from the XY scanning circuit 20 to the XY stage 13
By stopping the output of the output signal to the probe 11, the probe 11 stops at the recording position. Then, the control signal C changes from the write timing circuit 18 to the offset generation circuit 2
By being sent to 1, the offset voltage V _OF is output from the offset generation circuit 21 to the drive circuit 17.
As a result, the drive circuit 17 produces the drive signal S _D corresponding to the voltage obtained by superposing the offset voltage V _OF on the drive voltage V _D. As the piezo actuator 21 is driven by the generated drive signal S _D , the probe 11 moves the recording layer 1 as shown in FIG.
It is moved downward (-Z axis direction) in the figure until it comes into molecular contact with ₃ .

Thereafter, a recording pulse voltage V _PW in which a pulse voltage having a peak value of 2.5 V is superimposed on a bias voltage of 0.1 V
From the bias generation circuit 19 to the probe 11 and the base electrode 1.
By being applied between ₂ and ₂ , the recording bit 1 ₄ is generated at the recording position of the recording layer 1 ₃ as shown in FIG. Then, the output of the offset voltage V _OF from the offset generation circuit 21 to the drive circuit 17 is stopped, as shown in FIG. 1 (D), the distance between the probe 11 and the recording layer 1 ₃ is constant The probe 11 is moved upward (in the + Z axis direction) in the figure until the value becomes Z ₀ . Then, the output signal of the XY scanning circuit 20 is output to the XY stage 13 again, so that the probe 11 is scanned to the next recording position.

After that, by repeating the above operation, the recording bit 1 ₄ is generated at each recording position of the recording layer 1 ₃ .

The timing for scanning the probe 11 in the right direction (X-axis direction) in FIG. 2 and the timing for moving the probe 11 in the vertical direction (Z-axis direction) in FIG. 2 is as shown in FIG.
As shown in (A), the probe 11 may be moved in the Z-axis direction while scanning the probe 11 in the X-axis direction, and as shown in FIG.
The scanning of the probe 11 in the X-axis direction may be stopped only when the probe 11 moves in the Z-axis direction until it comes in contact with the molecule ₃ , and further, as shown in FIG. When moving, the scanning of the probe 11 in the X-axis direction may be stopped. The operation of the recording / reproducing apparatus 10 described above is performed when the probe 11 is scanned in the X-axis direction and moved in the Z-axis direction as shown in FIG.

As described above, the predetermined number of recording bits 1
₄ After recording on a recording medium 1, the left probe 11 was kept constant distance between the probe 11 and the recording layer 1 ₃ X
By scanning in the axial direction, the current J detected by the probe 11 at this time is converted into a voltage signal V by the current-voltage conversion circuit 14 and sent to the data demodulation circuit 23, whereby the recording data D is recorded by the data demodulation circuit 23. Demodulated.

[0038] As a result, the number of layers two layers recording layer 1 _3, in any of the recording medium 1 with four layers and sixth layer, the results shown below were obtained.

In an experiment in which the scanning distance Z ₀ between the probe 11 and the recording layer 1 ₃ was 1 nm, (a) the approach amount of the probe 11 to the recording layer 1 ₃ was 0.6 n.
When less than m, the recording error with a probability of about 1-2% with respect to the formation of 1024 recording bit 1 ₄ (i.e.,
It was observed that the recording bit 1 ₄ was not formed and the recording bit 1 _{4 with} a diameter of 20 nm or more was abnormally generated. Also, record bit 1 ₄
Is before and after the recording position generated abnormally, and in some cases the deviation of the intended recording position actually recording bits 1 ₄ is formed position (positional deviation of the recording bit) reaches more than 5 nm.

[0040] (b) In contrast, more than 0.6nm approach of the recording layer 1 ₃ of the probe 11 (in particular, 1～4N
when the m), the shape variation of the recording bit 1 ₄ is extremely small, and, following minute recording bits 1 ₄ 5Nmfai was formed. Also, the recording bit position shift is ± 1n
It was m or less. It should be noted that the reason why a good recording bit was formed even though the probe 11 was brought close to only 0.6 nm in the state of the distance Z ₀ = 1 nm was that adsorption on the surface of the recording medium 1 was performed because the experiment was performed in the atmosphere. 0.4 from the distance Z _{0 due} to molecular level contamination such as water
It is considered that the molecular contact occurred from the approach distance as small as about nm.

(C) Even when the probe 11 was pushed in by about 4 nm for the distance Z ₀ = 1 nm, no indentation or the like due to the tip of the probe 11 was observed on the recording layer 1 ₃ , the base electrode 1 ₂ and the substrate 1 ₁ . . Therefore, the distance Z ₀
Even when the probe 11 is moved to the recording layer 1 ₃ above, for the displacement to some extent (push), the probe 11
Alternatively, it is considered that the substrate 1 ₁ including the recording layer 1 ₃ is elastically deformed to maintain the state of molecular contact.

(D) In the above (c), the probe 11
The when pushed into the recording layer 1 ₃ as 5~7nm is a tendency that the size variation of the recording bit 1 ₄ increases were observed, which is considered to be because beyond the region of molecular contact of the present invention.

The area where the elastic deformation is maintained against the pushing amount is dependent largely like material of the substrate 1 _1, to control the amount of push while monitoring the current J flowing between the probe 11 and the recording medium 1 As a result, the desired molecular contact can be achieved stably without being affected by the material or environment. For example, in the above experiment, the current J is 100 nA or more (the bias voltage at this time is 100 nA).
mV, 1 MΩ or less in terms of resistance value), more preferably 1
until flowing above .mu.A, by approaching the relative distance between the probe 11 and the recording medium 1, formation of a good recording bit 1 ₄ (recording operation) can be realized. According to such a method, molecular contact can be controlled with good reproducibility even if the value of the distance Z ₀ is unknown before the pushing.

[0044] However, in the state of being molecules contacting the probe 11 to the recording medium 1, as compared to the state of release between the probe 11 and the recording layer 1 _3, excess current J during application of the recording pulse voltage V _PW may flow, as a result, there is a decrease in the shape deterioration and the recording probability of recording bit 1 ₄ occurs. In order to prevent this, it is desirable to provide a limiting resistance or load resistance, that is, to provide a resistive element or a region having low conductivity in a part of the path of the current J. Specifically, the output impedance of the bias generation circuit 19 is designed to be a specified value or more, or the input impedance of the current-voltage conversion circuit 14 is designed to be a specified value or more. Of course, probe 11
And between the current-voltage conversion circuit 14, or, between the bias generating circuit 19 and the base electrode 1 _2, a resistor or resistive element may be connected in series. It is also possible to form the insulating thin film layer such as SiO ₂ between the base electrode 1 ₂ and the recording layer 1 _2. The preferable resistance value at this time is the recording pulse voltage V
Depending on recording conditions, such as conditions (wave height value and width) and the recording layer 1 of ₂ thickness of _PW, but generally it is possible to prevent such deterioration of the shape of the recording bit 1 ₄ If the value of the above 1kΩ~10kΩ . On the other hand, in order to monitor the molecular contact state, it is preferable that the limiting resistance value is equal to or less than the contact resistance value (for example, 1 MΩ).

It is a schematic configuration diagram showing a second embodiment of the recording / reproducing apparatus of the present invention.

The recording / reproducing apparatus 110 of this embodiment comprises a multi-probe head 111 having 3 × 3 probes (only probes 111 _{11 to} 111 ₁₃ are shown), a lateral drive element 112,
The vertical drive element 113, the position control circuit 114, the recording voltage application circuit 115, the switching circuit 116, the detection current signal processing circuit 117, the control computer 118, and the laser light source 121.
A lens 122, a polygon mirror 123, a rotation speed control circuit 124, a position detection element 125, and a position detection signal processing circuit 126, and each probe generated when each probe is in molecular contact with the recording medium 101. The position of each probe is controlled based on the acting force with the recording medium 101.

Next, each component of the recording / reproducing apparatus 110 will be described in detail.

(1) Multi-probe head 111 The multi-probe head 111 is an electron force microscope (AF).
In this embodiment, a plurality of probes composed of soft elastic cantilevers used in M) are integrated on one substrate. In other words, the probe 111 ₁₁ illustrated left end, the cantilever 131 ₁₁ made of an elastic body, which has a tip 132 ₁₁ tip formed conductive to the cantilever 131 ₁₁ The same applies to the other probe .

The multi-probe head 111 can be manufactured as follows. Thickness 0.3μ due to thermal oxidation
m SiO ₂ film is formed on the surface of the Si substrate, and then a cantilever shape with a length of 100 μm and a width of 20 μm is formed into 3 ×.
3 to form a matrix. Subsequently, after forming an electric signal wiring pattern to the tip electrode, S
The multi-probe head 111 is formed by anisotropically etching the back surface of the i substrate with a KOH solution. continue,
Height of 5μ by electron beam deposition method of carbon etc.
The tip of m is installed on the tip of the cantilever. The elastic constant for the deflection of each probe tip manufactured on the thus completed multi-probe head 111 is 0.01 N / m.
It will be about. Further, considering the warp of each cantilever and the process error of the height of each probe, the positional variation in the height direction of each probe tip based on the multi-probe support member is about 1 μm. As the recording medium 101, one whose surface waviness is reduced to about 1 μm or less is used.

(2) Horizontal direction drive element 112, vertical direction drive element 113 and position control circuit 114 The horizontal direction drive element 112 is driven by the output signal of the position control circuit 114 to move the multi-probe head 111 in the X-axis direction in the drawing. It is moved in the Y-axis direction and the θ direction. The vertical drive element 113 is driven by the output signal of the position control circuit 114 to move the recording medium 101 in the Z-axis direction in the figure.

(3) Recording voltage application circuit 115 and switching circuit 116 The recording voltage application circuit 115 includes the probes and the recording medium 101.
And a switching circuit 116 for applying the recording voltage output from the recording voltage applying circuit 115 to only a predetermined probe.

(4) The detection current signal processing circuit 117, the control computer 118, and the detection current signal processing circuit 117 are connected to each probe and the recording medium 10.
The magnitude of the current that flows between 1 and 1 is detected and a playback signal is created. The control computer 118 has a position control circuit 114.
And the detection current signal processing circuit 117 and the switching circuit 116, respectively.

(5) Laser light source 121, lens 122, polygon mirror 123, rotation speed control circuit 124, position detecting element
125 and the position detection signal processing circuit 126 The laser light source 121 is for emitting the laser light L. The lens 122 is for condensing the laser light L emitted from the laser light source 121 on the cantilever of each probe. The polygon mirror 123 is for sequentially scanning the cantilever of each probe with the laser light L condensed by the lens 122. Rotation speed control circuit 124
Controls the rotation of the polygon mirror 123, and outputs the scanning position of the laser light L (that is, information on which probe cantilever is irradiated with the laser light L). The position detecting element 125 is for detecting the spot position on the light receiving surface of the reflected light from the cantilever of the probe irradiated with the laser light L. The position detection signal processing circuit 126 receives the laser beam L from the output signal of the rotation speed control circuit 124 (a signal indicating the scanning position of the laser beam L) and the output signal of the position detection element 125 (the position detection signal). For identifying the cantilever and detecting the displacement amount (deflection amount) of the cantilever in the Z-axis direction in the drawing.

Next, the distance adjustment between the multi-probe head 111 and the recording medium 101 will be described in detail.

Multi-probe head 111 and recording medium 101
The relative distance in the Z-axis direction in the figure between the vertical drive element 11 and
Controlled by 3. That is, for example, when the probe 111 ₁₁ at the left end in the drawing is brought closer to the recording medium 101 by a distance of 1 nm or less, an acting force is generated between the probe 111 ₁₁ and the recording medium 101, and this acting force causes an elasticity to support the probe 111 _11. The body cantilever 131 ₁₁ is bent. This amount of deflection is proportional to the magnitude of the acting force. Therefore, while detecting the amount of deflection of each cantilever,
Multi-probe head 111 using vertical drive element 113
By adjusting the distance and inclination between the recording medium 101 and the recording medium 101, it is possible to generate an acting force of a predetermined magnitude between all the probes and the recording medium 101, and the magnitude of each acting force. Can be suppressed within a certain range. The amount of deflection of each cantilever is detected by the method described below.

Laser light L emitted from the laser light source 121
After condensing the light with the lens 122, the rotation speed control circuit
Polygon mirror 123 controlled by 124 to rotate
Incident on. The rotation of the polygon mirror 123 causes the laser beam L to scan the back surface of the cantilever of each probe.
At this time, by rotating the polygon mirror 123 in the direction of the arrow in the figure, the cantilevers of the respective probes arranged in parallel in the direction perpendicular to the paper surface are also scanned. The position detection element 125 detects the light reflected from the back surface of the cantilever. Here, assuming that the length of each cantilever is d ₁ and the distance from the back surface of the cantilever to the position detection element 125 is d ₂ , when the deflection of the deflection amount ΔZ occurs at the tip of the cantilever,
The light spot on the position detecting element 125 is displaced by the distance 2 × (d ₂ / d ₁ ) × ΔZ. Therefore, based on the output signal of the position detection element 125, the position detection signal processing circuit 126
5 The deflection amount ΔZ of the tip of the cantilever can be detected by detecting the positional deviation of the light spot on the above. At this time, the laser beam L is reflected by the polygon mirror 123.
By scanning, the amount of deflection of the tip of each cantilever can be sequentially detected in a time division manner.

Next, the recording / reproducing operation of the recording / reproducing apparatus 110 will be described in detail.

Recording is performed by bringing each probe close to the recording medium 101 as described above. That is,
In the recording operation, the lateral position control signal is transmitted to the position control circuit 114.
Is sent to the lateral driving element 112, the tip of each probe is moved to a desired recording position on the recording medium 101. After that, a predetermined recording voltage is applied from the recording voltage applying circuit 115 to the probe selected by the switching circuit 116. At this time, the control computer 119 uses the signal from the position detection signal processing circuit 126 (that is, the amount of deflection of each cantilever) so that the molecular contact state is obtained at least during the period when the recording voltage is applied. The vertical driving element 113 is controlled so that the relative distance between each probe and the recording medium 101 is reduced.
Drive. The recording medium 101 and the recording signal used were the same as those used in the first embodiment. On the other hand, in the reproducing operation, the detected current signal processing circuit 118 detects the magnitude of the current flowing between each probe and the recording medium 101 in the state where the two-dimensional scanning is performed, and the reproduced signal is obtained.

By selecting the recording medium 101 and recording voltage (current) conditions, it is possible to apply a recording method that causes a local shape change. In this case, the amount of deflection of the cantilever at the recording position can be applied. (That is, the reproduction signal can be created from the output signal of the position detection signal processing circuit 126).

As a result of a recording / reproducing experiment using the recording / reproducing apparatus 110 having the above-mentioned configuration, for example, the probe is brought into molecular contact with the recording medium 101 at the time of recording, so that the probe is generated between the probe and the recording medium 101. 5 × 1 acting force
It has been clarified that the recording bit with high reproducibility (bit position accuracy, shape and recording probability) can be formed when it is set to 0 ⁻⁸ N to 1 × 10 ⁻⁷ N or more. However, in the case of a sample having two recording layers, stable recording was sometimes realized even under a molecular contact condition of about 1 × 10 ⁻⁸ N.

The recording / reproducing method and the recording / reproducing apparatus of the present invention are not limited to the above-described first and second embodiments, and plastic deformation does not occur on the surface of the recording medium or the tip of the probe. As long as the recording process is performed by increasing the current flowing between the probe and the recording medium to a certain extent and with the tip of the probe in molecular contact with the surface of the recording medium in a minute region. .

[0062]

Since the present invention is configured as described above, it has the following effects. (1) It is possible to form recording bits that are minute and have a uniform shape with good reproducibility. (2) It is extremely easy to install a method and means for bringing a probe relatively close to a recording medium until it comes into molecular contact with a conventional recording / reproducing apparatus of this type, which complicates and enlarges the recording process and recording mechanism. The present invention can be applied without inviting. (3) The reduction of the error rate at the time of recording and the high position accuracy of the recording bit are due to the recording format and the reproducing system.
Since the reproducing mechanism and the reproducing circuit can be simplified, simplification of the entire recording / reproducing apparatus can be achieved, and high speed, small size, and low price can be achieved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of a recording / reproducing apparatus of the present invention.

FIG. 2 is a diagram for explaining the operation of the recording / reproducing apparatus shown in FIG.

3A and 3B are diagrams showing each example of the timing of scanning of the probe in the X-axis direction and the movement of the probe in the Z-axis direction in the recording / reproducing apparatus shown in FIG. 1. FIG. Showing an example of moving the probe, (B) showing an example of stopping the scanning of the probe when moving the probe until it contacts the recording layer, and (C) showing a scanning of the probe when moving the probe. It is a figure which shows the example which stops.

FIG. 4 is a schematic configuration diagram showing a second embodiment of the recording / reproducing apparatus of the present invention.

[Explanation of symbols]

1, 101 recording medium 1 ₁ substrate 1 ₂ base electrode 1 ₃ recording layer 10, 110 recording / reproducing device 11 probe 12 piezo actuator 13 XY stage 14 current-voltage conversion circuit 15 sample hold circuit 16 servo circuit 17 drive circuit 18 writing timing circuit 19 Bias generation circuit 20 XY scanning circuit 21 Offset generation circuit 22 Data modulation circuit 23 Data demodulation circuit 111 Multi-probe heads 111 _{11 to} 111 ₃₃ Probe 112 Horizontal drive element 113 Vertical drive element 114 Position control circuit 115 Recording voltage application circuit 116 Switching circuit 117 Detection current signal processing circuit 118 Control computer 121 Laser light source 122 Lens 123 Polygon mirror 124 Rotational speed control circuit 125 Position detection element 126 Position detection signal processing circuit 131 _{11 to} 131 ₃₃ Cantilever 132 _{11 to} 132 ₃₃ Tip X, Y, Z axis

Front Page Continuation (72) Inventor Shunichi Shito, 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor, Ryo Kuroda 3-30-2, Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Katsunori Hatanaka 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (11)

[Claims] 1. A recording / reproducing method for recording recording information on the recording medium and reproducing the recorded recording information by utilizing a signal generated by a physical interaction between the recording medium and the probe. A recording / reproducing method, characterized in that the probe is brought into molecular contact with the recording medium during a period of recording the recording information on the medium. 2. The recording / reproducing method according to claim 1, wherein a contact resistance value between the recording medium and the probe when the probe is brought into molecular contact with the recording medium is 1 MΩ or less. 3. The recording / reproducing method according to claim 2, wherein a contact resistance value between the recording medium and the probe when the probe is brought into molecular contact with the recording medium is 100 kΩ or less. 4. During the period in which the probe is brought into molecular contact with the recording medium, a gap between the recording medium and the probe is 10 times.
^2. The recording / reproducing method according to claim 1, wherein the recording medium and the probe are brought close to each other to such an extent that an acting force of ^-8 N or more is generated. 5. During a period in which the probe is brought into molecular contact with the recording medium, a gap between the recording medium and the probe is 10 times.
5. The recording / reproducing method according to claim 4, wherein the recording medium and the probe are brought close to each other to such an extent that an acting force of ⁻⁷ N or more is generated. 6. When the distance between the recording medium and the probe is Z ₀ nm in a period other than the period for recording the recording information on the recording medium, the period for recording the recording information on the recording medium is , The recording medium and the probe (Z ₀
-4) The distances of about 1 nm or more are set.
Recording / playback method described. 7. The recording medium and the probe are brought close to each other by Z ₀ nm or more and (Z ₀ +3) nm or less in a period in which the recording information is recorded on the recording medium. Recording and playback method. 8. A recording / reproducing apparatus for recording recording information on the recording medium and reproducing the recorded recording information by using a signal generated by a physical interaction between the recording medium and the probe. A probe moving means for moving the probe in a direction perpendicular to the surface of the recording medium, and a driving means for driving the probe moving means. A recording / reproducing apparatus, characterized in that the probe moving means is driven so as to bring the probe into molecular contact with a recording medium. 9. The method according to claim 8, further comprising current limiting means for limiting a current flowing between the recording medium and the probe to 1 μA or less when the probe is brought into molecular contact with the recording medium. The recording / reproducing apparatus described. 10. The current limiting means is a resistance element provided in the current path.
The recording / reproducing apparatus described. 11. The recording / reproducing apparatus according to claim 10, wherein the resistance value of the resistance element is 1 MΩ or less.