JPH0498632A - Recording medium and information processing device using this medium and access method - Google Patents

Abstract

PURPOSE:To increase a recording density by providing continuous staircase-like rugged shapes on a surface and changing the thickness of a recording layer stepwise by the rugged shapes. CONSTITUTION:After a glass substrate 1 is washed, Cr is deposited as an under coating layer thereon and further Au is deposited by evaporation to form a counter electrode 2. A chloroform soln. prepd. by dissolving SOAZ at 0.2mg/ml concn. is then developed on a water phase consisting of pure water kept at 20 deg.C to form a monomolecular film on the water surface. The surface pressure of the monomolecular film is increased up to 20mN/m and further, while this pressure is kept constant, the electrode substrate is gently immersed into the water so as to cross the water surface and is further pulled up to accumulate two layers of the Y-shaped monomolecular films; in succession, the immersion distance of the substrate is decreased at 2mum pitch and two layers of the cumulative films are provided on the counter electrode, by which the recording layer 3 and the projecting step parts 4 are formed. The track pitch is made into several 100Angstrom to several mum in this way.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a recording medium that enables ultra-high density memory by using the principle of a scanning tunneling microscope (STM), and a recording/reproducing device using the same. The present invention relates to information processing devices including recording devices and playback devices, and access methods.

[Prior Art] In recent years, the use of memory materials has become the core of the electronics industry, such as computers and related equipment, video disks, digital audio disks, etc., and the development of these materials has been extremely active. The performance required of memory materials varies depending on the application, but in general, 1) high density and large storage capacity 2) fast response speed for recording and playback 3) low power consumption 4) high productivity (low price) Examples include cheap.

On the other hand, a scanning tunneling microscope (STM) was developed that can directly observe the electronic structure of surface atoms of conductors [G, B1nn
1g et al, PhysRev, Le
tt, 49, 57 (1982)] It has become possible to measure real space images with high resolution regardless of whether they are single crystal or amorphous.
Furthermore, it has the advantage of being able to observe with low power without damaging the medium due to the current, and furthermore, it can operate in the atmosphere and can be used for various materials, so it is expected to have a wide range of applications.

Such STM utilizes the fact that a tunnel current flows when a voltage is applied between a metal probe (probe electrode) and a conductive substance and the probe is brought close to a distance of about 10 nm (1 nm). This current is extremely sensitive to changes in the distance between the two, and by scanning the probe while keeping the tunneling current constant, it is possible to depict the surface structure in real space, and at the same time, it is possible to draw various information about the total electron cloud of surface atoms. information can also be read. At this time, the resolution in the in-plane direction is about one person. Therefore, by applying the principle of STM, it is sufficient to achieve the atomic order (
High-density recording and reproduction can be performed by several people. The recording and reproducing method at this time is to change the surface condition of the appropriate recording layer using high-energy electromagnetic waves such as particle beams (electron beams, ion beams) or X-rays, and energy rays such as visible and ultraviolet light. A method of recording and reproducing with STM, and a method of recording and reproducing with STM using a material that has a memory effect on the switching characteristics of voltage and current as a recording layer, such as a thin film layer of a π-electron organic compound or chalcogenide. Several methods have been proposed.

By the way, in order to actually perform recording and reproduction on a memory medium as an apparatus, it is necessary to perform so-called tracking, which is positioning and tracing to a data string. Tracking methods for this type of high-density memory include: 1) A method in which markers at reference positions are written in advance. (JP-A-64-53363, JP-A-64-53365
2) A method in which a V-shaped groove is formed in advance on the surface of the recording medium and the probe electrode is controlled so that it is always in the center of this groove.While forming the groove during recording, unevenness information is recorded in the groove. Then, when reading out, the method reads by tracing this groove.(Japanese Patent Application Laid-Open No.
107341, Japanese Unexamined Patent Publication No. 1-151035) 3) A method of writing or reading information along the crystal lattice arrangement arranged in stripes by applying the atomic arrangement of the crystal. (Japanese Unexamined Patent Publication No. 1-154332) 4) A conductive track electrode is embedded in the recording medium, and tracking is performed using a tunnel current between this electrode and a probe electrode. (Japanese Unexamined Patent Publication No. 1-133239) and the like have been proposed.

[Problems to be Solved by the Invention] 1) According to the method in which reference position markers are written in advance, recorded data can be written in two-dimensional areas, STMO high resolution and high resolving power are achieved, and the recording density is extremely high. However, in order to detect this reference position marker, the surface of the recording medium must be scanned in two dimensions, and it takes a considerable amount of time to find the reference marker.

2) There are the following problems in forming grooves for tracking on the surface of a medium. In order to form grooves corresponding to the recording bit size of about 100 people, about 300 grooves are required. To achieve this, processing using an ion beam is used. However, in order to control and process as many as 300 fine grooves at a pitch of 300 to 600 people, an ultra-precision stage with mechanical accuracy of about 30 to 60 people is required. This type of device is very large and has a limited handling environment, making it unsuitable for things that need to be produced in large quantities at low cost, such as memory media. Grooves can also be formed by electron beam processing or X-ray exposure, but in this case the width of the groove that can be formed is ~3000 mm.
This would make it impossible to perform high-density recording that takes advantage of the high resolution of STM.

3) When tracking the atomic arrangement of a crystal,
Although it is possible to take advantage of the high resolution of STM, the area of the recording surface required for the recording medium, for example, the recording density, can be reduced to 100 people per person.
If the recording capacity is 1012 bits, the area of the recording surface is ICm2, but it is difficult to easily obtain a crystal substrate with a striped lattice arrangement over such an area without disorder or defects in the lattice arrangement. It is difficult to meet the low cost and high productivity requirements of recording media.

4) The method of embedding a tracking electrode in a recording medium, applying a tracking signal to this electrode, and detecting this signal with a probe to perform tracking makes the control mechanism for the recording/reproducing device easier, but it Processing the electrodes and providing terminals for injecting tracking signals of two or three different frequencies not only results in extremely low recording density, but also complicates the recording medium creation process and reduces productivity and yield. and cannot supply low-cost media.

That is, the present invention solves the above-mentioned problems, realizes high-density recording and reproducing by taking advantage of the characteristics of STM, provides a low-cost and highly productive recording medium, an access method that enables high-speed recording and reproducing, and The present invention provides a recording and reproducing device using such a recording medium, and an information processing device including a recording device and a reproducing device.

[Means and effects for solving the problems] The present invention is characterized by: Firstly, a recording medium on which information is recorded and reproduced using a probe electrode has a continuous step-like uneven shape on the surface. A recording medium, secondly, the recording medium according to the first aspect, wherein the uneven shape changes the thickness of the recording layer in a stepwise manner; thirdly, the recording layer has a π electron level in the molecule. and a group having a σ electron level, and fourthly, the recording layer is made of an organic compound laminated on an electrode substrate provided on the substrate. The recording medium according to the second aspect, which includes a monomolecular film or a monomolecular cumulative film; A method for accessing a recording medium having a step-like unevenness on its surface, the method comprising: detecting an edge of the unevenness; scanning the probe electrode at an angle with the edge; An access method including the step of moving a recording medium or a probe electrode in a direction along the edge portion. Seventh, an access method for a recording medium having a step-like uneven shape on its surface, the method comprising: detecting the edge portion. an access method comprising: a step of determining an azimuth angle with respect to the edge of a data string to be recorded and reproduced; and a step of scanning a probe electrode in the data string direction starting from the edge portion; 5th, an information processing device having the recording medium according to any one of the above 6th items, and having the access method according to the 6th item; 9th, having the recording medium according to any one of the 1st to 5th items, and The present invention is an information processing apparatus having the access method as described in item 2 of the preceding statement.

In other words, one aspect of the present invention is to provide a stepped portion (edge) on the surface of a recording medium that has irregularities or changes in electronic state that are larger than the recorded information, and record information is two-dimensionally recorded and reproduced along this edge portion. Specifically, it provides a high-density, high-speed accessible recording medium.

A block diagram of such a recording medium is shown in FIG. In this figure, an electrode 2 and a recording layer 3 are laminated on a substrate 1, and steps are provided by changing the thickness of the recording layer in a continuous step-like manner.

By the way, in the recording/reproduction using a recording medium and the tracking method for this purpose in the present invention, a voltage is applied between a probe electrode (conductive probe) and a conductive substance, and the distance between the two is maintained at 10 Å or less. It takes advantage of the fact that tunnel current flows when Further, according to the access method of the present invention, the probe electrode detects the first edge portion and reads data by two-dimensionally scanning the probe electrode along the edge portion, so that the data writing area can be accessed at high speed.

The access method of the present invention will be explained below based on the drawings.

In FIG. 2, reference numeral 6 denotes a recording/reproducing area, and 11 a stage for supporting a recording medium. This stage is driven in the Y-axis direction by a linear actuator 16. 13 is a recording/reproducing head which supports the probe electrode 12 and has X or Z respectively.
The position is controlled by an axially driven actuator 15.14.

The distance between the recording medium surface and the probe electrode is controlled by a tunnel current flowing between the recording medium surface and the probe electrode. This is done by detecting the tunnel current flowing between the recording medium probe electrodes using the bias voltage (8) by the load resistor RL, amplifying it by the amplifier 21, determining the appropriate probe height by the probe height detection circuit 22, and by the biaxial drive control circuit 25. Probe height is adjusted.

The recording/reproducing area 6 is determined using the edge 4 as a reference. That is, the X-axis drive control section 26 and the actuator 15
Accordingly, the probe electrode 12 scans in the X-axis direction. At this time, when the probe electrode approaches the edge portion 4, the tunnel current increases rapidly between the probe electrode and the electrode at the edge portion. Edge detector 2 detects this rapidly increasing tunnel current.
Detect with 3. Based on this detection signal, the X-axis drive control circuit reverses the scanning direction of the probe. Then, after a certain period of time has elapsed, the scanning direction of the probe electrode is reversed again and scanning is performed in the direction toward the edge portion. At this time, a drive signal is sent to the Y-axis drive control circuit to move the stage by one step in the Y-axis direction.

By repeating the above operations, the probe electrode can always scan the recording/reproducing area along the edge portion and at a certain angle with respect to the edge portion.

When recording on a recording medium, a write voltage is applied from the probe electrode through the SW from the data modulator 28 based on the point in time when the probe electrode detects the edge portion 4 and performs inversion scanning in the X-axis direction.

At this time, a series of data pulse trains are recorded until the probe electrode scans in the X-axis direction for a certain period of time and then starts reversing scanning in the edge direction again.

By performing this recording operation every time the probe electrode detects the edge portion 4, a data string at a certain angle to the edge portion is written, and the Y-axis stage is sequentially moved in synchronization with this to create a two-dimensional An area 6 in which data is recorded is formed.

During reproduction, the probe electrode is scanned with the edge portion as a reference, similar to during recording. At this time, the direction adjustment between the X-axis scanning direction of the probe electrode and the recorded data string was
A so-called wobbling method as disclosed in Japanese Patent No. 4-15727 may be used, or correction may be made when data is demodulated using a technique such as pattern matching that scans an area two-dimensionally.

FIG. 3(a) shows how data is recorded on the surface of the recording medium. 5 is the data recording bit, 31 (solid arrow) is the trajectory of the probe tip when the probe electrode scans away from the edge, and 32 (broken arrow) is the trajectory of the probe tip as the probe electrode moves toward the edge. It is.

FIG. 3(b) shows a case where the edge portion 4 is not a perfect straight line but has irregularities. Even in such a case, there is no problem in recording and reproducing since the data string is written so as to follow the edge portion. That is, the shape of the edge portion has a large tolerance for finishing accuracy.

Furthermore, since two-dimensional scanning is performed along this edge, the probe electrode can be guided to any data recording area using this edge. For example, when a recording medium is first installed in an information processing apparatus, an error occurs in the positional relationship between the probe electrode and the recording area of the recording medium due to the mechanical precision of the installation. This error is usually 10 to 10
It is about 0 μm. This is much larger than the data recording area. However, by using this edge detection scan, data areas can be easily found and tracked. Furthermore, according to the recording medium and access method of the present invention, the edge portion has a step and is arranged in a stripe or matrix.
X, Y, 2) coordinates can be determined. Therefore,
Detection of any location becomes easier, and access speed is expected to improve.

As a method for forming the step portion (edge) according to the present invention, for example, the following method can be considered. First, a conductive material is formed on the substrate to serve as an electrode facing the probe electrode, and then a recording layer is uniformly laminated over the entire surface of the facing electrode. Thereafter, edges are formed in a desired shape by decreasing or increasing the laminated area of the recording layer on the substrate as needed so that the recording layer has a step-like shape when viewed in cross section. Alternatively, after forming the edges, electrodes may be formed and a recording layer may be provided separately.

Although it is possible to apply a vapor deposition method, a cluster ion beam method, etc. as a specific method for forming the edge portion, the Langmuir-Prodgett method (LB method) is preferred among known conventional techniques due to its controllability, ease, and reproducibility. is extremely suitable. According to this LB method, a monomolecular film of an organic compound having a hydrophobic site and a hydrophilic site in one molecule or a cumulative film thereof can be easily formed on a substrate, and the thickness is on the order of a molecule. , and can stably supply a uniform and homogeneous ultra-thin organic film over a large area.

In addition, in the LB film manufacturing apparatus used in the present invention, in order to make the immersion and lifting distance correspond to the pitch of the stepped portion, a vibration isolator was installed in the water phase, and further, the substrate was driven up and down by a conventional DC motor using a piezo element. . More specifically, using a probe, for example, HOPG (Highly-Orien
ted-Pyrolithic-Gtraphite)
It is sufficient to measure the lattice spacing of , and drive the substrate with a piezo element so as to correspond to the desired track pitch.

Therefore, in the method for forming the step portion according to the present invention, the pitch can be easily formed from several hundred to several μm, and therefore it is possible to increase the recording density.

The recording layer used in the present invention is made of a material that has a memory switching phenomenon (electrical memory effect) in current-voltage characteristics, for example, molecules that have both a group having a π electron level and a group having only a σ electron level. It becomes possible to use an organic monomolecular film laminated on the electrode or a cumulative film thereof.

Since most organic materials generally exhibit insulating or semi-insulating properties, there is a wide variety of organic materials having a group having a π electron level that can be applied in the present invention. Examples of structures of dyes having a π-electron system suitable for the present invention include phthalocyanine, dyes having a porphyrin skeleton such as tetraphenylporphyrin, azulene dyes having squarylium groups and croconic methine groups as bonding chains, quinoline, benzothiazole, Cyanine-based similar dyes, such as benzoxazole, in which two nitrogen-containing heterocycles are bonded by a squarylium group and a croconic methine group, or cyanine dyes, fused polycyclic aromatics such as anthracene and pyrene, and aromatic and heterocyclic compounds and polymers of diacetylene groups, derivatives of tetracyanoquinodimethane or tetrathiafulvalene, analogs thereof, and charge transfer complexes thereof, and metal complexes such as ferrocene and trisbipyridine ruthenium complexes. Examples include compounds.

Examples of polymeric materials suitable for the present invention include addition polymers such as polyacrylic acid derivatives, condensation polymers such as polyimide, ring-opening polymers such as nylon, and biopolymers such as bacteriorhodopsin.

The electrical memory effect of compounds with these π-electron levels has been observed in films with a thickness of several tens of micrometers or less;
When using the recording/reproducing method described above, the distance between the probe electrode and the electrode facing it (counter electrode) must be made close so that a tunnel current flows between the two, so the film thickness of the recording layer according to the present invention is is 3 Å or more and 100 Å
Hereinafter, the thickness is preferably 3 Å or more and 30 Å or less.

In the present invention, any material may be used as the substrate for supporting the thin film laminated with organic materials as described above as long as the surface is smooth, and the material of the counter electrode provided on the substrate may also be used. Any material having high conductivity may be used, such as Au or Pt.

Metals such as Ag, Pd, Af, In, Sn, Pb, and W, and their alloys, as well as graphite, silicide, and conductive oxides such as ITO, as well as many other metals (
These materials can be considered to be applied to the present invention. Conventionally known thin film techniques are sufficient for forming electrodes using such materials. However, for the electrode material that is directly formed on the substrate, it is desirable to use a conductive material that does not form an insulating oxide when forming the LB film on the surface, such as a noble metal or an oxide conductor such as ITO. No matter which material is used, it is preferable that the surface thereof be smooth.

Furthermore, any material may be used for the probe electrode as long as it exhibits conductivity (for example, Pt).

Examples include Pt-Ir, W, Au, and Ag. The tip of the probe electrode needs to be as sharp as possible to increase the resolution of recording, playback, and erasure. In the present invention, a probe electrode is produced by controlling the shape of the tip of a needle-shaped conductive material using an electropolishing method, but the method and shape of the probe electrode are not limited thereto. Furthermore, the number of probe electrodes does not need to be limited to one; a plurality of probe electrodes may be used, such as one for position detection and one for recording/reproduction.

Next, an information processing apparatus using the recording medium of the present invention will be explained with reference to the block diagram of FIG. In FIG. 4, reference numeral 12 denotes a probe electrode for applying a voltage to the recording medium, and a voltage is applied from this probe electrode to the recording layer 3 to perform recording and reproduction.

The target recording medium is placed on the XY stage II. 47 is a probe current amplifier; 46 is a servo circuit that reads the probe current and controls fine movement mechanisms 44 and 45 using piezoelectric elements so that the height of the probe electrode is constant; 41 is a probe electrode 12 and a counter electrode 2; Recorded between
This is a power supply for applying a pulse voltage for erasing.

Since the probe current changes rapidly when applying a pulse voltage, the servo circuit 46 turns on the HOLD circuit.
The output current is controlled to be constant during that time.

43 is an XY scanning drive circuit for controlling the movement of the XY force direction probe electrode 12. 11 and 42, the distance between the probe electrode 12 and the recording medium is roughly controlled in advance so that a probe current of about 10-'A is obtained, or the relative displacement between the probe electrode and the substrate in the x and y directions is large (fine movement). outside the control mechanism).

All of these devices are centrally controlled by a microcomputer 49. Further, 5o represents a display device.

In addition, the mechanical performance in movement control using piezoelectric elements is shown below.

Z direction fine movement control range: 0. 1 nm”-ILL
mZ direction coarse movement control range: lOnm-10mm Tolerance: <lnm (during coarse motion control) [Examples] Examples of the present invention will be described below.

15.1 In this example, a recording medium of the type shown in FIG. 1 was produced. First, an optically polished glass substrate 1 was cleaned using a neutral detergent and Triclean, and then Cr was deposited as an undercoat layer to a thickness of 50 layers by vacuum evaporation (resistance heating), and then Au was deposited to a thickness of 400 layers by the same method. A counter electrode 2 was formed by vapor deposition.

Next, a chloroform solution in which squarylium-bis-6-octylazulene (hereinafter abbreviated as 5OAZ) was dissolved at a concentration of 0.2 mg/mρ was spread on an aqueous phase consisting of pure water at a water temperature of 20°C, and a monomolecular film was formed on the water surface. was formed. Wait for the solvent to evaporate, increase the surface pressure of the monolayer to 20 mN/m,
Furthermore, while keeping this constant, the electrode substrate was gently immersed across the water surface at a speed of 5 mm/min, and then pulled up again to accumulate two Y-shaped monomolecular films, and then the immersion distance of the substrate was 2 μm. The recording layer 3 and the convex step portion (edge) 4 were thus formed by decreasing the pitch and providing a two-layer cumulative film on the counter electrode. The height of the stepped portion at this time is 30 people.

Recording, reproducing, and erasing experiments were conducted on the recording medium prepared by the method described above using the information processing apparatus shown in FIG.

First, FIG. 5 shows an example of the configuration of an information processing apparatus that implements the recording medium access method according to the present invention. FIG. 6 shows an example of the locus of the tip of the probe electrode on the recording medium. Further, FIG. 7 shows waveform examples of each signal line of the information processing apparatus of FIG. 5 during reproduction and recording, respectively. This will be explained below according to the drawings.

In FIG. 5, 1, 2, 3.4 are the recording medium according to this embodiment, 11 is a stage, and X, Y, and Z are arranged to draw the probe electrode into an arbitrary recording area on the recording medium. It can move within a range of 10mm in each direction. 61 is a cylindrical P
The ZT actuator is used to scan the probe electrode 12 along the data row on the recording medium, and can move up to 2 μm in each of the X, Y, and Z directions.

Probe electrode 12 is connected to current amplifier 62 . The output of the current amplifier 62 is input to a sample hold circuit 64 via a logarithmic compression circuit 63. The output signal (a) of the sample hold circuit is input to a comparator 65, a peak hold circuit 66, and a high pass filter 70, respectively.

The output (b) of the peak hold circuit 66 is output to the error amplifier 67.
and a low-pass filter 68. The output of the error amplifier is connected to a cylindrical PZT Δ2 drive electrode. On the other hand, the output of the low-pass filter 68 is input to a comparator 69 through an attenuator VR. The output (d) of the high-pass filter is connected to the other input of comparator 69. Furthermore, the output of the comparator 69 is input to a data demodulator of a data modulation/demodulation section 75 .

The data modulation output of the data modulation/demodulation section is connected to a pulse generator 73, combined with a DC bias voltage (1), and connected to the recording medium electrode 2 and the stepped portion 4.

The tracking control section 74 drives the cylindrical PZT actuator 61 via an up/down counter 71 and a D/A converter 72. up/down counter 71
Comparator 6 for edge detection is connected to the up input (g) of
5 and the up control signal from the tracking control section. On the other hand, the down input (f) of the deep down counter 71 is connected to the down control signal of the tracking control section. The count output of the up/down counter is converted into an analog voltage by the D/A converter 72 and drives the cylindrical PZT by ΔX.

Assuming a data reproducing operation, the trajectory of the probe electrode 12 on the recording medium is as shown in FIG. 6(a). stage 11
Cylindrical PZ from the probe position 80 initially set by
When T61 starts data scanning and detects edge 4 through a locus 81, the scanning of the probe electrode is reversed and becomes a locus 82. After further scanning a certain distance, it turns around again and moves in the direction toward edge 4.

The above operation is repeated, and when the probe electrode 12 detects five data bit rows, it sequentially scans this data row while adjusting the scanning direction.

The scanning direction of the probe electrode is controlled by a variable resistor R2 using a control signal.
ΔX/ of the cylindrical PZT actuator 61
This is done by changing the drive ratio of ΔY. Although not shown in Fig. 6, detection of the proper scanning direction is performed using the wobbling voltage (k).
The determination is made by driving the tunnel voltage by ΔY and monitoring the peak-held envelope signal (C) of the tunnel voltage at this time.

Further, FIG. 6(b) shows the state in which the probe electrode 12 scans the data string of the recording medium in a sectional view taken along the line AA' in FIG. 6(a). To control the distance between the probe electrode and the surface of the recording medium, a signal (b) obtained by peak-holding the logarithmically compressed value of the tunnel current is input to a reference voltage V by an error amplifier 67.
ms and drives the cylindrical PZT by ΔZ.

With this control, the probe electrode scans to encompass the convex part of the data string or the part with the highest electronic state.

Next, the operation during reproduction will be explained using the timing chart of FIG. 7 showing the states of each signal.

The tunneling current detected by the probe electrode is shown in Figure 5.6.
After being amplified by the current amplifier 2, it is logarithmically compressed by 63 and sampled and held by 64. During playback, this sample and hold circuit enters a through state and outputs the pressure of the logarithmic compressor as it is.

The sample and hold output (a) is compared with a threshold voltage V8□ by an edge detection comparator to detect when the probe electrode approaches an edge. However, ■, 2
is thicker than the output voltage according to the data string (set.

The edge-detected signal forces the up-down counter to switch to up-count operation. After further up-counting a certain count value, it switches to down-counting again. The up and down control signals of the up/down counter at this time are shown in FIGS. 7(g) and 7(f), respectively. Further, the ΔX drive output is shown in FIG. 7(h).

This operation allows the probe electrode to scan without colliding with the edge portion of the recording medium.

The sample hold output (a) extracts a high frequency component, that is, a data information component, using a high-pass filter, and converts it into an envelope signal (C
) is compared with an appropriately attenuated voltage to obtain binarized data (e). The respective input signals of the comparators at this time are shown in FIGS. 7(C) and (d). Further, the binarized signal is shown in FIG. 7(e). In addition, the envelope signal (c) is
The peak hold output (b) is integrated by the low pass filter 68.

Next, the operation at the time of recording is shown in the seventh column, which represents the state of each signal.
This will be explained using the timing chart shown in the figure and FIG.

The pressure signal (a) of the sample hold 64 is compared with V□ by the comparator 65, and when edge approach is detected, Van is first set to a predetermined level and a write operation begins.

After waiting for time for the control of the distance between the probe electrode and the recording medium to become stable, the sample hold control signal (i) is put into a hold state in synchronization with the data write clock, and the pulse generator 73 generates a write pulse (j). This data pulse is written until the probe electrode performs inversion scanning, and as soon as the probe performs inversion scanning, it returns to reading scanning, and the data writing operation is in a standby state until the next edge is detected.

Next, the recording and reproducing method will be explained using FIG. However, as the probe electrode 12, a platinum/rhodium probe electrode made by an electric field polishing method is used, and this probe electrode 12 is designed so that a voltage can be applied to the recording layer 3.
The distance (Z) is controlled by a piezoelectric element. Furthermore, the probe electrode 12 is in-plane (X
.

The fine movement control mechanism system is designed so that movement can be controlled also in the Y) direction.

Further, the probe electrode 12 can directly perform recording, reproduction, and erasing. Further, the recording medium is placed on a high-precision XY stage 11 and can be moved to any position. Therefore, by this movement control mechanism, the probe electrode 12
Recording, playback, and erasing can be performed on tracks at arbitrary positions.

A recording medium having the recording layer 3 described above was set in a recording/reproducing apparatus. At this time, the Y direction of the track and the Y direction of the recording/reproducing device were installed so that they were almost parallel. Next, +1.5■ between the probe electrode 12 and the facing electrode 2 of the recording medium.
voltage was applied, and the distance (Z) between the probe electrode 12 and the counter electrode 2 was adjusted while monitoring the current flowing through the recording layer 3. At this time, the probe current for controlling the distance 2 between the probe electrode 12 and the counter electrode 2 is set to 10-"A≧
It was set so that Ip≧10-”A. Next, distance 2
While keeping constant, probe electrode 12 is scanned in the X direction, and after confirming that a track is formed on the recording medium, move probe electrode 12 to any track (recording layer).
held above. Next, the probe electrode was scanned in the Y direction while keeping the distance between the probe electrode and the counter electrode constant. At this time, it has been found that by performing tracking using the method described above, it is possible to scan the probe electrode 12 on any desired track without straying from it.

Next, while scanning the probe electrode 12 on the track, information was recorded at a pitch of 50 people.

Recording of such information is performed with the probe electrode 12 on the + side and the counter electrode 2 on the one side, so that the electrical memory material is in a low resistance state (O
A triangular wave pulse voltage higher than the threshold voltage VthoN shown in FIG. 10 was applied so as to change to the N state. Thereafter, the probe electrode was returned to the recording start point and scanned over the track again. As a result, the recording bit was 0.7m.
A probe current comparable to that of a human flowed, indicating that the probe was in an ON state. In the above playback experiment, the pit error rate was 3×10-''.

In addition, as a result of setting the probe electrode to an IOV higher than the threshold voltage Vthoyy at which the electric memory material changes from the ON state to the OFF state and tracing the recorded position again, all recorded states were erased and the state transitioned to the OFF state. Also confirmed.

The thickness of each 5OAZ layer was determined by small-angle X-ray diffraction and was about 15.

Example 1 and Example 1 (Similarly, after forming the counter electrode 2 on the glass substrate 1, 2, 4, 6, 8, and 10 layers of polyimide LB film were accumulated in the X direction and the Y direction, respectively, and recording was performed. Layer 3 was formed.The method for forming the polyimide LB film is as follows.

Polyamic acid (molecular weight approximately 200,000) at a concentration of 1 x 10-3
A solution of dimethylacetamide dissolved at
/v) to prepare a polyamic acid octadecylamine salt solution. The solution was spread on an aqueous phase consisting of pure water at a water temperature of 20°C to form a monomolecular film on the water surface. The surface pressure of this monomolecular film was increased to 25 mN/m, and while keeping this constant, the substrate was stretched 5 mm across the water surface.
The Y-type monomolecular film was accumulated by dipping and pulling up while moving at a speed of 1/min.

Subsequently, by decreasing the immersion distance of the substrate at a pitch of 1 μm, a cumulative film of 2.4.6.8.10 layers was formed on the counter electrode. Next, the bent substrate was rotated 90'' to form a cumulative film of 2,4,6,8,10 layers perpendicular to the cumulative film.

Further, these films were heated at 300'C for one layer to form polyimide.

The thickness per polyimide layer is determined by ellipsometry.
Approximately four people were required by law. Furthermore, a schematic diagram of the recording medium produced in this manner is shown in FIG.

When recording and reproducing experiments were conducted in the same manner as in Example 1 using such a recording medium, the pit error rate was lXl0
-', and deletion was also possible.

After immersing a glass substrate with a counter electrode formed thereon in the same manner as in Example 1 in pure water at a water temperature of 20°C, a polyamic acid similar to that in Example 2 was spread on the water surface to form a monomolecular film. Formed. The surface pressure of this monomolecular film was increased to 25 mN/m,
Furthermore, while keeping this constant, the substrate was pulled up across the water surface at a rate of 5 mm/min. The immersion distance of such a substrate was reduced to 500 people in the same manner as in Example 2, and 1 person was immersed on the substrate.
．． 3.5.7.9 layers of cumulative films were formed in the X and Y directions, respectively.

Further, these films were heated at 300° C. for 10 minutes to form polyimide.

When recording and reproducing experiments were carried out in the same manner as in Example 1 using such a recording medium, the bit error rate was lXl.
0-' and could be erased.

叉”U pull A A counter electrode and a recording layer were formed in the same manner as in Example 2.

However, recording media were formed by increasing the immersion distance of the substrate as the number of records of the recording layer increased.

When recording and reproducing experiments were conducted in the same manner as in Example 1 using such a recording medium, the pit error rate was 2X10.
-' and could be erased.

If the glass substrate was washed with hexamethyldisilazane (HMD)
After hydrophobic treatment by leaving it in saturated steam of S) for a day and night,
2.4 in each of the X direction and Y direction in the same manner as in Example 2.
, 6.8. A step consisting of 10 layers of polyimide cumulative film was formed.

Next, as in Example 1, an undercoat layer of Cr with a thickness of 50 layers and Au with a thickness of 500 layers was formed on the substrate by vacuum evaporation.

Thereafter, a two-layer polyimide cumulative film was formed as a recording layer.

When recording and reproducing experiments were conducted using such a recording medium in the same manner as in Example 1, the bit error rate was 3X1.
0-' and could be erased.

[Effects of the Invention] As described above, according to the present invention, 1) the track pitch of the recording area can be controlled to several hundreds to several μm, and the recording area can be made into units; , the total area of the recording surface is not controlled, and the recording density can be maximized to the maximum.

2) Since the edge-based tracking operation is performed on a two-dimensional data area, the processing time for the tracking operation is extremely small compared to 1 bit of data, allowing for high-speed data reading. Writing becomes possible.

3) Since the data string is written based on the edge of the recording medium, when the probe electrode scans the data bit string during reading, it is possible to accurately predict the timing at which the data bit is recorded, which eliminates wobbling etc. Therefore, the scanning direction for the data string can be determined reliably.

4) The track forming material and the recording layer can be made of the same material and can be easily formed, resulting in high productivity and low cost.

There are effects like this.

[Brief explanation of drawings]

FIG. 1 is a diagram illustrating the configuration of a recording medium according to the present invention. FIG. 2 is a diagram illustrating an access method according to the present invention. FIG. 3 is a diagram for explaining the present invention in detail. FIG. 4 is a configuration block diagram of an information processing device according to the present invention. FIG. 5 is a diagram showing the configuration of an information processing device that implements the access method of the present invention. FIG. 6 is a diagram showing the locus of the probe electrode of the information processing device in FIG. 5 on the surface of the recording medium. FIG. 7 shows signal waveforms during reproduction by the information processing apparatus shown in FIG. FIG. 8 is a diagram showing signal waveforms of various parts of the information processing apparatus of FIG. 5 during recording. FIG. 9 shows a pulse signal waveform applied when recording on the recording medium of the present invention. 1... Substrate 2... Electrode (counter electrode) 3... Recording layer 4... Step portion (edge portion) 5... Recording bit 6... Recording/reproducing area 11... XY stage 12 ... Probe electrode 13 ... Recording and reproducing head 4 ... Actuator 5 that drives the head in the Z-axis direction
... Actuator 6 that drives the head in the X-axis direction.
・Actuator that drives the stage in the Y-axis direction・
・Amplifier 2...Probe height detection circuit 3...Edge detector 4...Data demodulator 5...Two-axis drive control circuit 6...X-axis drive control circuit 7...Y-axis drive Control circuit 8...Data modulator 1...Trajectory 32 when the probe electrode scans in the direction away from the edge...Trajectory l when the probe electrode scans in the direction approaching the edge...Pulse power supply 2...Coarse movement mechanism 3...XY direction scanning drive circuit 4...2 direction fine movement control mechanism 5...XY direction fine movement control mechanism 6...Servo circuit 7...Probe current amplifier 8... - Coarse movement drive circuit 9... Microcomputer O... Display device 1... Cylindrical PZT actuator 2... Current amplifier 3... Logarithmic compression circuit 4... Sample hold circuit 5... Comparator 6...Peak hold circuit 7...Error amplifier 8...Low pass filter 9...Comparator O...High pass filter...Up/down counter 2...D/A converter 3... ...Pulse generator for data writing 4...Tracking control section 5...Data modulation/demodulation section 76...Stage control section 80...Initialized probe position 81...Trajectory from which data scanning started 82...Trajectory reversed by edge 1 Figure

Claims (9)

[Claims] (1) A recording medium on which information is recorded and reproduced using probe electrodes, the recording medium having a continuous step-like uneven shape on its surface. (2) The recording medium according to claim 1, wherein the uneven shape is formed by changing the thickness of the recording layer in a stepwise manner. (3) The recording layer has a group having a π electron level in the molecule and a σ
3. The recording medium according to claim 2, comprising an organic compound having a group having an electronic level. (4) The recording layer includes a monomolecular film or a monomolecular cumulative film of an organic compound laminated by a Langmuir-Prodgett method on an electrode substrate provided on a substrate. recording medium. (5) The recording medium according to claim 1, wherein the height difference of the stepped uneven shape is 3 to 100 Å. (6) A method for accessing a recording medium having a step-like uneven shape on its surface, which includes a step of detecting a stepped portion of the uneven shape, and a step of scanning the probe electrode at an angle with the stepped portion. , a step of moving a recording medium or a probe electrode in a direction along the stepped portion. (7) A method for accessing a recording medium having a step-like uneven shape on its surface, which includes a step of detecting the stepped portion, a step of determining an azimuth angle of a data string to be recorded and reproduced with respect to the stepped portion, and a step of determining the azimuth angle with respect to the stepped portion of the data string to be recorded and reproduced. 1. An access method comprising: scanning a probe electrode in a data column direction starting from the data column. (8) comprising a recording medium according to any one of claims 1 to 5;
An information processing device comprising the access method according to claim 6. (9) having a recording medium according to any one of claims 1 to 5;
An information processing device comprising the access method according to claim 7.