JP2866165B2 - Recording medium, method of manufacturing the same, information processing method, and information processing apparatus - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information processing apparatus for performing recording / reproduction with a probe electrode, an information processing method, a recording medium used for the same, and a method for manufacturing the same.

[Prior Art] In recent years, applications of memory materials are at the core of the electronics industry, such as computers and related equipment, video disks, digital audio disks, and the like, and the development of such materials has been extremely active. The performance required for memory materials varies depending on the application, but in general, high density, large recording capacity, fast response time for recording and reproduction, low power consumption, high productivity, low price, etc. Can be raised.

Until now, semiconductor memories and magnetic memories using magnetic materials or semiconductors as the main material were mainly used.However, with the advancement of laser technology in recent years, inexpensive and high-density optical memories using organic thin films such as organic dyes and photopolymers have been developed. Recording media has appeared.

On the other hand, recently, a scanning tunneling microscope (hereinafter abbreviated as STM) capable of directly observing the electronic structure of surface atoms of a conductor has been developed [G. Binnig et al. Phys. Rev. Lett, 49, 57 (198
2)], it is possible to measure high resolution real-space images regardless of whether they are single crystal or amorphous, and they also have the advantage that they can be observed with low power without damaging the sample by current. It is expected to have a wide range of applications because it operates and can be used for various materials.

STM utilizes the fact that a tunnel current flows when a voltage is applied between a metal probe (probe electrode) and a conductive substance to a distance of about 1 nm. This current is very sensitive to changes in the distance between them. By scanning the probe so as to keep the tunnel current constant, it is possible to read various kinds of information on all electron clouds in the real space. At this time, the resolution in the in-plane direction is about 0.1 nm.

Therefore, if the principle of STM is applied, it is possible to perform high-density recording / reproduction sufficiently in the atomic order (sub-nanometer). For example, in a recording / reproducing apparatus disclosed in Japanese Patent Application Laid-Open No. 61-80536, atomic particles adsorbed on the medium surface are removed by an electron beam or the like, writing is performed, and this data is reproduced by STM.

A method has been proposed in which recording and reproduction are performed by STM using a material having a memory effect on the switching characteristics of voltage and current as a recording layer, for example, a thin film layer of a π-electron organic compound or a chalcogen compound [ JP-A-63-161552, JP-A-63-161553]. According to this method, if the recording bit size is 10 nm, large-capacity recording / reproduction of 10 ¹² bits / cm ² is possible.

[Problem to be Solved by the Invention] FIG. 7 shows a configuration example of an information processing apparatus to which STM is applied. This will be described below with reference to the drawings.

101 is a substrate, 102 is a metal electrode layer, and 103 is a recording layer. 201 is an XY stage, 202 is a probe electrode, 203 is a probe electrode support, 204 is a Z-axis linear actuator that drives the probe electrode in the Z direction, 205 and 206 are linear actuators that drive the XY stage in the X and Y directions, respectively.
07 is a pulse voltage circuit.

Reference numeral 301 denotes an electrode layer 1 from the probe electrode 202 via the recording layer 103.
This is an amplifier that detects the tunnel current flowing to 02. 302
Is a logarithmic compressor for converting the change in tunnel current into a value proportional to the gap distance between the probe electrode 202 and the recording layer 103, 30
This is a low-pass filter for extracting the surface unevenness component of the third recording layer 103. An error amplifier 304 detects an error between the reference voltage V _REF and the output of the low-pass filter 303, and a driver 305 drives the actuator 204. Reference numeral 306 denotes a drive circuit for controlling the position of the XY stage 201. 307 is a high-pass filter that separates data components.

FIG. 8 shows a cross section of a conventional recording medium and the probe electrode 202.
Show the tip of.

101 is a substrate, 102 is an electrode layer, 103 is a recording layer, and 104 is a track. 202 is a probe electrode.

401 is a data bit recorded on the recording layer 103, 40
Reference numeral 2 denotes crystal grains formed when the electrode layer 102 is formed on the substrate 101. The size of the crystal grains 402 is 30 to 50 when a normal vacuum deposition method, a sputtering method, or the like is used as a method for manufacturing the electrode layer 102.
It is about nm.

The gap between the probe electrode 202 and the recording layer 103 can be kept constant by the circuit configuration shown in FIG. That is, a tunnel current flowing between the probe electrode 202 and the recording layer 103 is detected, and after passing through a logarithmic compressor 302 and a low-pass filter 303, this value is compared with a reference voltage so that the comparison value approaches zero. By controlling the Z-axis linear actuator 204 that supports the probe electrode 202,
And the recording layer 103 can be kept constant.

Further, the probe electrode 202 traces the surface of the recording medium by driving the XY stage 201, and the data of the recording layer 103 can be detected by separating the high frequency components of the point signal.

FIG. 9 shows the signal intensity spectrum with respect to the frequency of the signal at this point.

signal f ₀ following frequency components is due gently rolling the medium due to warping of the substrate 101, distortion, or the like. signal centered on f ₁ is due to unevenness of the surface of the recording layer 103, it is due to the crystal grain 402 primarily occurs during electrode material formed. f ₂ is a carrier component of the recording data, 403 is a data signal band. f ₃ is a signal component generated from the arrangement of atoms and molecules in the recording layer 103. f _T is a tracking signal. Seventh
Although not shown in the information processing apparatus of FIG, a signal so that the tracking signal f _T can track the data sequence probe electrodes 202, or forming a step on a medium, and out of the track detection This is achieved by writing the signals that can be generated.

When the recording medium shown in the conventional example is used, there are the following problems.

(1) To perform high-density recording utilizing the high resolution which is a feature of the STM, we must place the data signal band 403 between f ₁ and f _3. In this case, using a high pass filter 303 of the cut-off frequency f _c for separating the data component. However, base of the signal components of f ₁ overlaps the data signal band 403. This signal component of f ₁ is the electrode layer 102 crystal grains 402
This is because the data recording size and the bit interval are close to 1 to 10 nm with respect to the crystal grain 402 of 30 to 50 nm.

For this reason, the S / N ratio for data reproduction is reduced, and the error rate of read data is significantly increased.

(2) tracking signal f _T can not be placed only in the vicinity of f _0. Therefore, the tracking signal f _T is the tracking data tracking accuracy becomes a much lower frequency than the data signal band 403 falls. This results in problems such as an increase in the data read error rate and a decrease in the reliability of the information processing apparatus.

In view of the above problems, an object of the present invention is to provide a high S / N ratio.
It is an object of the present invention to provide a recording medium capable of high-speed reproduction, an information processing apparatus and an information processing method using the recording medium.

Further, an object of the present invention is to provide a recording medium in which the S / N ratio is sufficiently improved, the error rate of read data is significantly reduced, and the tracking accuracy of the tracking is significantly improved, and an information processing apparatus using such a recording medium. , An information processing method.

[Means and Actions for Solving the Problems] The above object is achieved by the present invention described below.

That is, the first of the present invention, in a recording medium on which information is recorded or reproduced by applying a voltage from a probe electrode, a substrate, and formed on the substrate, the surface on the side facing the probe electrode, 1nm difference in height of unevenness
Or less, an electrode layer having a smooth surface having a size of 1 μm square or more, a track formed adjacent to the smooth surface and formed in a convex or concave shape with respect to the smooth surface, and formed on the smooth surface of the electrode layer. And a recording layer whose characteristics transition between two or more states having different electric conductivities when a voltage is applied.

Second, in a method of manufacturing a recording medium having a track on which information is recorded or reproduced by applying a voltage from a probe electrode, the difference in height of the unevenness is 1 nm or less, and the size is 1 μm or more. A step of preparing a base material having a smooth surface and a convex or concave portion adjacent to the smooth surface and having a shape corresponding to the track; and forming an electrode layer on the smooth surface and the convex or concave portion of the base material. Bonding a substrate to a surface of the electrode layer opposite to the surface in contact with the base material, transferring the electrode layer to the substrate by peeling the electrode layer from the base material, A recording in which the characteristics are transited between two or more states having different conductivity by applying a voltage on the smooth surface of the base material of the transferred electrode layer and the surface in contact with the protrusions or recesses of the base material. And forming the layer. A method for producing a recording medium according to symptoms.

Third, using the recording medium of the first invention, the electrode layer and the conductive probe while relatively scanning the surface of the recording layer of the recording medium with a conductive probe disposed close to the surface. The information is recorded by applying a pulse voltage between the electrodes and the electrode layer and the conductive probe while relatively scanning the surface of the recording layer on which the information is recorded by a conductive probe disposed close to the surface. And an information processing method for reproducing information by applying a bias voltage between the two and detecting a current flowing through the conductive probe.

Fourth, the recording medium of the first invention, a conductive probe disposed close to the surface of the recording layer of the recording medium, and a scanning unit that relatively scans the conductive probe with respect to the recording medium. A recording circuit for recording information by applying a pulse voltage between the electrode layer of the recording medium and the conductive probe, and applying a bias voltage between the electrode layer of the recording medium and the conductive probe, A reproduction circuit for reproducing information recorded on the recording layer on the recording medium by detecting a current flowing through the conductive probe.

By providing a recording medium having a smooth surface according to the present invention, it has become possible to make full use of the function of an information processing apparatus to which the principle of STM is applied.

 Hereinafter, the present invention will be described with reference to the drawings.

FIG. 1 shows a sectional view of a recording medium according to the present invention. 101
Is a substrate, 102 is an electrode layer having a smooth surface, 103 is a recording layer, 10
4 is a truck.

FIG. 3 is a cross-sectional view showing each step of the production of a recording medium according to the present invention.

In FIG. 3A, first, a smooth substrate 11 is prepared. This smooth substrate needs to have a smooth surface with a height difference of 1 nm or less and a size of 1 μm square or more.

Surface irregularities are measured by bringing the tip of a microprobe close to the sample substrate surface, measuring the interatomic force acting between the tip of the microprobe and the atoms on the sample substrate surface, and observing the sample surface shape using AFM (Atomic). -Force-Microscopy).

By using such an AFM, it is possible to measure the surface shape of a sample at an atomic order resolution regardless of the conductivity or insulation of the sample. The present inventors evaluated the surfaces of various materials using AFM, and found that the following materials were suitable as the smooth substrate 11 in the present invention.

. Crystal cleavage plane: The crystal cleavage plane can easily obtain an extremely smooth surface, and the crystal material is mica or Mg
O, Tic, Si, HOPG, and the like.

. Melted glass surface ... for example, float glass, #
7059 fusion fused quartz.

When the surface shape of the above material was measured by AFM, 10
The difference in the height of the surface irregularities was 1 nm or less in all the μm square regions. In particular, the mica cleavage plane has few steps in the lattice plane generated during cleavage, and has a spatial frequency over a large area (mm).
3.3 × 10 ⁵ cm ^-1 or less height difference of unevenness is 1 nm or less,
It is suitable as a smooth substrate used in the present invention.

Next, as shown in FIG. 3B, a track 104 is formed on the smooth substrate 11. The track 104 is used for efficient random access, positioning, and tracking for performing tracking to a data string when recording and reproducing data, and is formed by providing a concave or convex step larger than the recorded information. . When the track 104 is formed in a convex shape, a thin film is formed on the smooth substrate 11 and formed by ordinary photoetching. Preferably, it is formed by a lift-off method. Further, it is more preferable to selectively deposit and form the track 104 pattern by maskless processing. In the case of a concave shape, it is formed by processing the smooth substrate 11 directly by ordinary photoetching. It is preferable to selectively etch and form the track 104 pattern by maskless processing. Furthermore, in any case, care should be taken not to roughen the smooth surface other than the track 104.

Next, as shown in FIG. 3C, an electrode layer 102 is formed on the smooth substrate 11 including the tracks 104. As the electrode layer 102 according to the present invention, a material having high conductivity and further having poor adhesion to the smooth substrate 11 is preferable. For example, Au, A
Noble metals such as g, Pt, and Pd; alloys such as Au-Pd and Pt-Pd; As a method for forming an electrode using such a material, a conventionally known thin film forming technique is sufficient.

Next, as shown in FIG. 3 (d), an adhesive layer 1 is formed on the electrode layer 102.
Form 3. The adhesive layer 13 according to the present invention is preferably a solventless type having no volume shrinkage, for example, an epoxy resin-based, α-cyanoacrylate-based insulating adhesive or a conductive adhesive such as Epotek silver series. Can be

Next, as shown in FIG.
Attach. In this step, when the substrate 101 and the electrode layer 102 are directly bonded, for example, in the case of eutectic bonding, electroforming, or the like, the adhesive layer 13 can be omitted. Substrate 101 according to the present invention
Any material such as metal, glass, ceramics, and plastic materials can be used when the bonding layer 13 is interposed. In the case of directly bonding to the substrate 101, a relatively smooth material is preferable. Further, when the electrode layer 102 is thick, the substrate 101 can be omitted.

Next, as shown in FIG. 3 (f), the smooth substrate 11 is
By peeling off from the substrate 102, a smooth electrode substrate having a smooth surface with a difference in height of surface unevenness of 1 nm or less and a size of 1 μm □ or more can be formed.

Next, as shown in FIG. 3 (g), the electrode layer of the smooth electrode substrate
By forming the recording layer 103 on the recording layer 102, a recording medium is obtained.

As the recording layer 103, a material having a memory switching phenomenon (electric memory effect) in current-voltage characteristics, for example, a molecule having both a group having a π electron level and a group having only a σ electron level is used as an electrode. It is possible to use an organic monomolecular film or a cumulative film thereof laminated on the organic monomolecular film. The electric memory effect is different when a thin film such as the above-mentioned organic monomolecular film and its cumulative film is disposed between a pair of electrodes.
State showing more than one conductivity (Fig. 11 ON state, OFF state)
By applying a voltage exceeding a threshold value that can make a transition to the low-resistance state (ON state) and a high-resistance state (OFF state), switching (switching) can be performed. Each state can be held (memory) without applying a voltage.

In general, most of organic materials have insulating or semi-insulating properties, and thus the organic materials having a group having a π-electron level applicable in the present invention are remarkably diversified. As a structure of a dye having a π-electron system suitable for the present invention, for example, phthalocyanine, a dye having a porphyrin skeleton such as tetraphenylporphyrin, an azulene-based dye having a squarylium group and a croconic methine group as a bonding chain, quinoline, benzothiazole, Cyanine-like dyes in which two nitrogen-containing heterocycles such as benzoxazole are bonded by a squarylium group and a croconic methine group, or condensed polycyclic aromatics such as cyanine dyes, anthracene and pyrene, and aromatic rings and heterocyclic compounds Polymerized chain compound and diacetylene group, furthermore, derivatives of tetracyanoquinodimethane or tetrathiafulvalene and their analogs and their charge transfer complexes, and furthermore, ferrocene, trisbipyridine ruthenium complex, etc. Metal complex compounds.

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

Regarding the formation of the recording layer 103, specifically, it is possible to apply a vapor deposition method, a cluster ion beam method, or the like,
Among the known prior arts from the viewpoint of controllability, easiness and reproducibility, the LB method 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 has a thickness on a molecular order. In addition, a uniform and uniform organic ultrathin film can be stably supplied over a large area.

In the LB method, when a molecule having a structure having a hydrophilic site and a hydrophobic site in the molecule and the balance between them (the balance of amphipathicity) is appropriately maintained, the molecule moves down the hydrophilic group on the water surface. This is a method of forming a monomolecular film or a cumulative film thereof by utilizing a monomolecular layer.

Examples of the group constituting the hydrophobic site include various generally known saturated and unsaturated hydrocarbon groups, condensed polycyclic aromatic groups, and linear polycyclic phenyl groups. Each of these constitutes a hydrophobic site alone or in combination with a plurality thereof. On the other hand, the most typical constituents of the hydrophilic site include, for example, carboxyl group, ester group, acid amide group, imide group, hydroxyl group, and amino group (1, 2, tertiary and quaternary). And the like.

An organic molecule having both a hydrophobic group and a hydrophilic group in a well-balanced manner can form a monomolecular film on the water surface, and is a very suitable material for the present invention.

Although the electric memory effect of these compounds having a π-electron level has been observed at a film thickness of several tens nm or less, the thickness is preferably 5 to 300 mm from the viewpoints of film formability and uniformity.

FIG. 2 shows a frequency spectrum of a point signal when the recording medium according to the present invention is used in the information processing apparatus shown in FIG.

signal f ₀ following frequency components is due gently rolling the medium due to warping of the substrate 101, distortion, or the like. f ₂ is a carrier component of the recording data, 403 denotes a data signal band. f ₃
Is a signal component generated from the arrangement of atoms and molecules in the recording layer 103. _FT is a tracking signal. centered signal of the f ₁ is intended to slight unevenness of the surface of the base material is transferred to the surface of the electrode layer 102, the irregularities are created smaller than the recording signals equal to or recorded signal data. The change in this unevenness is 1 nm or less in recording and reproduction using STM. In the recording medium according to the present invention, the size of the smooth surface on the surface of the recording layer 103 is 1 μm square or more. As a result, the following operation and effect can be obtained.

(1) recording layer 103 signal component due to unevenness of the surface f ₁ and the data signal band 403 is never overlap, there is no reduction in S / N due to spreading of the spectrum of f _1. That is, the data error rate can be reduced.

(2) tracking signal f _T can be placed in the vicinity of the data signal band 403. Since a high tracking frequency can be used, sufficient tracking accuracy of the tracking can be ensured.

(3) Since the tracking frequency is high, when a step for this tracking is formed on the recording medium, the shape may be substantially the same as the data bit size, and the tracking is performed without sacrificing the recording density. be able to.

(4) Since there is no unevenness on the surface of the recording layer 103, the displacement of the Z-axis of the probe electrode 202 during XY scanning while keeping the gap between the surface of the recording layer 103 and the probe electrode 202 constant is small. For this reason, the XY stage 201 can be driven extremely quickly.

(5) Since there is no unevenness on the surface of the recording layer 103, the tip of the probe electrode 202, that is, the position of the tip atom through which the tunnel current flows is stably selected. Uneven recording layer 103
The so-called ghost phenomenon in which a tunnel current flows between a plurality of atoms of the probe electrode 202 and the recording layer 103 as seen on the surface is eliminated.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples.

Embodiment 1 Embodiment 1 of the present invention will be described with reference to FIGS. 3 (a) to 3 (g).

First, as shown in FIG. 3 (a), a mica plate is cleaved in the air to form a smooth substrate 11.

Next, as shown in FIG. 3 (b), a track 104 having a width of 0.1 μm, a pitch of 1.0 μm and a depth of 50 ° was formed on the smooth substrate 11 by a focused ion beam. The focused ion beam has an accelerating voltage of 40
The test was performed under the conditions of KV, ion current of 14 pA, dose of 1.0 × 10 ¹⁶ / cm ² , and Au ions.

Next, as shown in FIG. 3C, a gold film is formed on the smooth substrate 11 by a vacuum evaporation method to form an electrode layer 102. The electrode layer 1
02 was performed under the conditions that the substrate temperature was kept at room temperature, the deposition rate was 10 ° / sec, the ultimate pressure was 2 × 10 ⁻⁶ Torr, and the film thickness was 2000 °.

Next, as shown in FIG. 3 (d), an adhesive layer 13 (Konishi High Temp HT-10) is applied on the electrode layer 102.

Next, as shown in FIG.
Paste on top. The bonding of the substrate 101 was performed under the conditions of a pressure of 5 kg / cm ² , a temperature of 200 ° C., and a curing time of 1 hour.

Next, as shown in FIG. 3 (f), the smooth substrate 11 is
By peeling off from the substrate 102, a smooth electrode substrate including the substrate 101, the adhesive layer 13, the electrode layer 102, and the track 104 was obtained. Observation of the surface of the thus obtained smooth electrode substrate by STM revealed that the difference in height of the surface irregularities at 10 μm □ was 1 nm or less.

Next, as shown in FIG. 3 (g), a four-layer polyimide LB film was formed on the smooth electrode substrate to form a recording layer 103. Hereinafter, a method for forming the recording layer 103 using the polyimide LB film will be described.

The polyamic acid represented by the formula (1) was dissolved in a mixed solvent of N, N'-dimethylacetamide-benzene (1: 1 V / V) (concentration in terms of monomer: 1 × 10 ⁻³ M), and N was separately adjusted. , N−
1 × 10 ^-3 M of dimethyloctadecylamine in the same solvent
The solution was mixed at a ratio of 1: 2 (V / V) to prepare a polyamic acid octadecylamine salt solution represented by the formula (2).

This solution was spread on an aqueous phase composed of pure water at a water temperature of 20 ° C., and a monomolecular film was formed on the water surface. After removing the solvent by evaporation, the surface pressure was increased to 25 mN / m. After keeping the surface pressure constant, the above-mentioned smooth electrode substrate was immersed gently at a speed of 5 mm / min in a direction across the water surface, and then gently pulled up at a speed of 5 mm / min to produce a two-layer Y-type monomolecular cumulative film. . This operation was repeated to form a four-layer monomolecular cumulative film of polyamic acid octadecylamine salt. Next, the substrate was decompressed (~ 1 mmH
g) Below, calcination by heating at 300 ° C. for 10 minutes to imidize polyamic acid octadecylamine salt (formula 3), Four layers of polyimide single molecule cumulative films were obtained.

Next, using the recording medium produced by the method described above,
When the surface shape was examined by the information processing apparatus shown in FIG. 7, the surface of the recording medium reflected the smooth surface of the electrode and the track 104, and the track 104 had a height of 50 μm at 10 μm square.
The difference in height of the surface irregularities other than the track 104 was 1 nm or less. Therefore, the track 104 could be clearly identified.

Next, an experiment of recording and reproduction was performed. A probe electrode 202 made of platinum / rhodium was used as the probe electrode 202. The probe electrode 202 is for controlling the distance (Z) to the surface of the recording layer 103, and the distance (Z) is finely controlled by a piezoelectric element so as to keep the current constant. Further, the linear actuators 204, 205, and 206 are designed so that fine movement control can be performed in the in-plane (X, Y) direction while keeping the distance Z constant.

Further, the probe electrode 202 can directly perform recording / reproduction / erasing. The recording medium is a high-precision XY stage
It is placed on 201 and can be moved to any position.

The recording medium having the recording layer 103 in which four polyimide layers were accumulated was placed on the XY stage 202. Next, a voltage of +1.5 V was applied between the probe electrode 202 and the electrode layer 102 of the recording medium, and the distance (Z) between the probe electrode 202 and the surface of the recording layer 103 was adjusted while monitoring the current. At this time, the probe current Ip for controlling the distance Z between the probe electrode 202 and the surface of the recording layer 103 was set to be 10 ⁻¹⁰ A ≧ Ip ≧ 10 ⁻¹¹ A.

Next, while scanning the probe electrode 202,
04 was detected. The track 104 is used for positioning during recording and reproduction and tracking to a data string. At this time, when the probe electrode 202 approaches the track 104, when the track 104 is convex, the tunnel current between the probe electrode 202 and the track 104 is rapidly increased, and when the track 104 is concave, It utilizes the fact that the tunnel current drops sharply. Also, high-speed access is performed by recording and reproducing recording information two-dimensionally along the track 104. Then 100Å
Information was recorded at the pitch. In recording such information, the probe electrode 202 is set to the + side and the electrode layer 102 is set to the-side, and the electric memory material (the four polyimide LB films) changes to a low resistance state (ON state) as shown in FIG. Voltage V _th ON
A rectangular pulse voltage (first pulse voltage) exceeding the threshold voltage was applied. Thereafter, the probe electrode 202 was returned to the recording start point, and after the track 104 was detected, the recording layer 103 was scanned again. At this time, adjustment was made so that Z = constant at the time of reading the recording. As a result, in the recording bit, 10
A probe current of about nA flowed, indicating that the probe was in the ON state.

Note that the probe voltage is changed from the ON state of the electric memory material.
The threshold voltage _Vth OFF that changes to the OFF state was set to 10 V (second pulse voltage), which was higher than the threshold voltage, and the recording position was traced again. As a result, it was confirmed that all the recording states were erased and the state transited to the OFF state. Further, when the reading error rate of the information was examined with the reading speed kept constant, it was found that the reading error rate was 10 ^-4 in the prior art, but was significantly improved to 10 ^{-7 in the} present embodiment. In addition, since the track has a small difference in height of the surface irregularities of the recording medium, the step can be formed to be low, so that the change in the Z axis of the probe electrode 202 can be suppressed small, and information can be read,
We also confirmed that random access can be performed at high speed.

Embodiment 2 Embodiment 2 of the present invention will be described with reference to FIGS. 4 (a) to 4 (e).

First, as shown in FIG. 4A, the mica plate is cleaved in the air to form a smooth substrate 11.

Next, as shown in FIG. 4B, a track 104 having a width of 0.1 μm, a pitch of 1.0 μm and a depth of 100 ° was formed on the smooth substrate 11 by a focused ion beam. The focused ion beam was performed under the conditions of an acceleration voltage of 40 KV, an ion current of 14 pA, a dose of 1.0 × 10 ¹⁶ / cm ² , and Au ions.

Next, as shown in FIG. 4C, a gold film is formed on the smooth substrate 11 by a vacuum evaporation method to form an electrode layer 102. The electrode layer 102 maintains the substrate temperature at room temperature, and has a deposition rate of 10 ° / sec,
The test was performed under the conditions of an ultimate pressure of 2 × 10 ⁻⁶ Torr and a film thickness of 5000 °.

Next, as shown in FIG.
Then, the electrode layer 102 and the substrate 101 are eutectic-bonded by heating with a heater to maintain a constant temperature, and then lightly rubbing the surface of the electrode layer 102 formed on the smooth substrate 11 onto the substrate 101. The bonding maintains the substrate temperature at 400 ° C and applies a pressure of 2
The test was performed under the conditions of kg / cm ² and a retention time of 1 minute.

Next, as shown in FIG.
The substrate was peeled off from 2 to obtain a smooth electrode substrate including the substrate 101, the electrode layer 102, and the tracks 104. Observation of the surface of the smooth electrode substrate thus obtained by STM revealed that the difference in height of the surface irregularities was 10 nm or less at 10 μm square.

Next, as shown in FIG. 4 (f), a four-layer polyimide LB film was formed on the smooth electrode substrate to form a recording layer 103.

Next, using the recording medium produced by the method described above,
When the surface shape was examined by the information processing apparatus shown in FIG. 7, the surface of the recording medium reflected the smoothness of the electrodes and the tracks 104. At 10 μm square, the tracks 104 had a height of 50 μm.
The difference in height of the surface irregularities other than the track 104 was 1 nm or less. Therefore, the track 104 could be clearly identified.

Next, experiments of recording, reproduction, and erasing were performed, and it was confirmed that recording, reproduction, and erasing could be performed in the same manner as in Example 1.

Embodiment 3 Embodiment 3 of the present invention will be described with reference to FIGS. 5 (a) to 5 (f).

First, as shown in FIG. 5 (a), a mica plate is cleaved in the atmosphere to form a smooth substrate 11.

Next, as shown in FIG. 5B, a track 104 having a width of 0.1 μm, a pitch of 1.0 μm and a depth of 100 ° was formed on the smooth substrate 11 by a focused ion beam. The focused ion beam has an accelerating voltage
The test was performed under the conditions of 40 KV, an ion current of 14 pA, a dose of 1.0 × 10 ¹⁶ / cm ² , and Au ions.

Next, as shown in FIG. 5C, an Au-Pd film is formed on the smooth substrate 11 by a vacuum evaporation method to form an electrode layer 102. The electrode layer 102 maintains the substrate temperature at room temperature, and has a deposition rate of 10 ° / se.
c, the ultimate pressure was 2 × 10 ⁻⁶ Torr, and the film thickness was 1000 ° C.

Next, as shown in FIG. 5D, nickel is formed on the electrode layer 102 by electroforming to obtain a substrate 101. The electroforming uses a Watt bath to maintain the temperature at 50 ° C., the current density is 0.06 A / cm ² ,
The electroforming was performed for 2 hours to obtain a thickness of 100 μm.

Next, as shown in FIG. 5 (e), the smooth substrate 11 is
By peeling off from the substrate 102, a smooth electrode substrate composed of the substrate 101, the electrodes 102 and the tracks 104 was obtained. Observation of the surface of the smooth electrode substrate thus obtained by STM revealed that the difference in height of the surface irregularities was 10 nm or less at 10 μm square.

Next, as shown in FIG.
A recording layer 103 was formed by forming a layer of a polyimide LB film.

Next, using the recording medium produced by the method described above,
When the surface shape was examined by the information processing apparatus shown in FIG. 7, the surface of the recording medium reflected the smoothness of the electrode and the track 104. At 10 μm square, the track 104 had a height of 5 μm.
The difference between the heights of the surface irregularities other than the tracks 104 was 1 nm or less. Therefore, the track 104 could be clearly identified.

Next, experiments of recording, reproduction, and erasing were performed, and it was confirmed that recording, reproduction, and erasing could be performed in the same manner as in Example 1.

Embodiment 4 Embodiment 4 of the present invention will be described with reference to FIGS. 6 (a) to 6 (g).

First, as shown in FIG. 6 (a), a mica plate is cleaved in the air to form a smooth substrate 11.

Next, as shown in FIG. 6B, a resist pattern 22 is formed on the smooth substrate 11 by an ordinary photolithography process. As the resist pattern 22, RD-2000N (manufactured by Hitachi Chemical) was used.

Next, as shown in FIG. 6C, SiO ₂ is deposited to a thickness of 50 ° and a track 104 is formed by a lift-off method.

Next, as shown in FIG. 6 (d), a gold film is formed on the smooth substrate 11 including the track 104 by a vacuum evaporation method, and the electrode layer 10 is formed.
Form 2. The electrode layer 102 was formed at a substrate temperature of room temperature, a deposition rate of 10 ° / sec, an ultimate pressure of 2 × 10 ⁻⁶ Torr, and a film thickness of 5000 °.

Next, nickel is formed on the electrode layer 102 by electroforming as shown in FIG. The electroforming was performed using a Watt bath at a temperature of 50 ° C., under the conditions of a current density of 0.06 A / cm ² and an electroforming time of 2 hours to obtain a thickness of 100 μm.

Next, as shown in FIG.
The substrate was peeled off from 2 to obtain a smooth electrode substrate including the substrate 101, the electrode layer 102, and the tracks 104. Observation of the surface of the smooth electrode substrate thus obtained by STM revealed that the difference in height of the surface irregularities was 10 nm or less at 10 μm square.

Next, as shown in FIG.
A recording layer 103 was formed by forming a layer of a polyimide LB film.

Next, using the recording medium produced by the method described above,
When the surface shape was examined by the information processing apparatus shown in FIG. 7, the surface of the recording medium reflected the smoothness of the electrodes and the tracks 104. At 10 μm square, the tracks 104 had a height of 50 μm.
The difference in the height of the surface irregularities other than the track 104 was 1 nm or less. For this reason, the track could be clearly identified.

Next, experiments of recording, reproduction, and erasing were performed, and it was confirmed that recording, reproduction, and erasing could be performed in the same manner as in Example 1.

[Effects of the Invention] As described above, the present invention has the following effects.

(1) By transferring the surface shape of the substrate,
The difference in the height of the surface irregularities other than the track is 1 nm or less,
It is possible to form a recording medium whose tracks can be clearly distinguished.

(2) Since the surface shape of the base material can be transferred, a smooth surface can be formed at an arbitrary position on the substrate, and a reference marker and the like can be formed at the same time.

(3) After the electrode layer is formed on the base material, it can be attached to the substrate, so that the substrate can be of any material and form. For example, taking a recording medium as an example, a control circuit for writing and reading is incorporated on a Si chip, and the electrode substrate of the present invention is formed using this chip as a substrate. This makes it possible to provide a recording medium in which a write / read control circuit and a recording layer are formed integrally.

By applying a recent micromechanics technology, a drive actuator is incorporated on a Si chip, and the electrode layer of the present invention is provided on this actuator to provide a recording medium with a fine movement mechanism.

Further, if such a recording medium is used, the error rate of read data can be remarkably reduced, the tracking accuracy can be significantly improved, and high-speed reproduction can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a recording medium used in the present invention, FIG. 2 is a diagram of a frequency spectrum of a reproduced signal of the present invention, and FIGS. 3 to 6 are manufacturing process diagrams in each embodiment. 7 is a configuration diagram of an information processing apparatus to which STM is applied, FIG. 8 is a schematic cross-sectional view of a conventional recording medium, FIG. 9 is a diagram of a frequency spectrum of a reproduction signal of the conventional example, FIG.
FIG. 11 is a waveform diagram of a pulse voltage applied when recording is performed on the recording medium of the present invention, and FIG. 11 is a current-voltage characteristic graph. 101: substrate, 102: electrode layer 103: recording layer, 11: smooth substrate 104: track

──────────────────────────────────────────────────続 き Continued on the front page (31) Priority claim number Japanese Patent Application No. 2-66805 (32) Priority date Hei 2 (1990) March 19 (33) Priority claim country Japan (JP) (72) Inventor Ken Eguchi 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Yuko Morikawa 3-30-2 Shimomaruko 3-chome, Ota-ku, Tokyo Inside Canon Inc. (72) Hiroshi Matsuda Tokyo 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Toshihiko Takeda 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) References JP-A-3-71453 ( JP, A) JP-A-3-503463 (JP, A) JP-A-3-15649 (JP, A) JP-A-4-1950 (JP, A) JP-A-4-90151 (JP, A) (58) ) Surveyed field (Int.Cl. ⁶ , DB name) G11B 9/00

Claims (12)

(57) [Claims] 1. A recording medium on or from which information is recorded or reproduced by applying a voltage from a probe electrode,
A substrate, formed on the substrate, on the surface on the side facing the probe electrode, the difference in height of the unevenness is 1 nm or less, and the size is 1 μm square or more. An electrode layer having tracks formed in a convex or concave shape with respect to a smooth surface, and between two or more states formed on the smooth surface of the electrode layer and having different electrical conductivity from each other by applying a voltage. A recording medium comprising: a recording layer whose characteristics change. 2. The recording medium according to claim 1, wherein the recording layer is made of an organic material having molecules having both a group having a π-electron level and a group having only a σ-electron level. 3. The recording medium according to claim 2, wherein said recording layer comprises a monomolecular film of said organic material or a cumulative film of said monomolecular film. 4. The recording medium according to claim 1, wherein said recording layer has a thickness in a range of 5 ° to 300 °. 5. A method for manufacturing a recording medium having a track on or from which information is recorded or reproduced by applying a voltage from a probe electrode, wherein the difference in height of the unevenness is 1 nm or less and the size is 1 μm □ or less. Preparing a base material having a smooth surface and a convex portion or a concave portion adjacent to the smooth surface and corresponding to the track; and forming an electrode layer on the smooth surface and the convex portion or the concave portion of the base material. A step of bonding a substrate to a surface of the electrode layer opposite to a surface in contact with the base material, a step of transferring the electrode layer to the substrate by peeling the electrode layer from the base material, By applying a voltage on the smooth surface of the base material of the electrode layer transferred to the surface and the surface in contact with the protrusions or recesses, the characteristics are changed between two or more states having different conductivity from each other. Forming a recording layer. Method of manufacturing a recording medium characterized. 6. The method for manufacturing a recording medium according to claim 5, wherein said recording layer is formed of an organic material having a molecule having both a group having a π-electron level and a group having only a σ-electron level. . 7. The production of a recording medium according to claim 6, wherein the recording layer is formed from a monomolecular film of the organic material or a cumulative film of the monomolecular film by a Langmuir-Blodgett method (LB method). Method. 8. The method for manufacturing a recording medium according to claim 5, wherein said recording layer is formed to have a thickness in a range of 5 ° to 300 °. 9. The method for manufacturing a recording medium according to claim 5, wherein the smooth surface of the base material is a cleavage surface of a crystal substrate. 10. The method for manufacturing a recording medium according to claim 5, wherein the smooth surface of the base material is a glass surface formed by melting. 11. The recording medium according to claim 1, wherein said electrode is formed by relatively scanning a surface of a recording layer of said recording medium with a conductive probe disposed close to said surface. The information is recorded by applying a pulse voltage between the layer and the conductive probe, and the surface of the recording layer on which the information is recorded is relatively scanned by a conductive probe disposed close to the surface, An information processing method for reproducing information by applying a bias voltage between an electrode layer and a conductive probe and detecting a current flowing through the conductive probe. 12. A recording medium according to claim 1, a conductive probe disposed close to a surface of a recording layer of said recording medium, and a conductive probe positioned relative to said recording medium. Scanning means for scanning, a recording circuit that records information by applying a pulse voltage between the electrode layer of the recording medium and the conductive probe, and between the electrode layer of the recording medium and the conductive probe. A reproducing circuit for reproducing information recorded on the recording layer of the recording medium by applying a bias voltage and detecting a current flowing through the conductive probe;