JPH0528549A - Recording medium and information processor - Google Patents

Abstract

PURPOSE:To assure the smoothness and hydrophobic property of the recording surface of the recording medium which executes recording, reproducing, etc., of information by using a probe electrode applying the principle of STM and eventually to attain high S/N, high-density recording, reproducing, etc., by high- speed access. CONSTITUTION:This recording medium is used for the information processor for executing recording, reproducing, etc., of the information by detecting the current flowing in an element by the probe electrode and is constituted by providing an amorphous carbon layer 104 on a substrate electrode 102 to be disposed opposite to the probe electrode 201 and laminating a recording layer 103 having an electric memory effect on this amorphous carbon layer 104.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording medium used as a large-capacity and high-density recording medium to which the principle of a scanning tunneling microscope is applied, and an information processing apparatus using the recording medium.

[0002]

2. Description of the Related Art In recent years, the use of memory devices has been at the core of the electronics industry for computers and related equipment, video discs, digital audio discs, etc., and their development is actively progressing. Generally, the performance required for a memory device is (1) high density, large recording capacity (2) fast recording / reproducing response speed (3) small error rate (4) low power consumption (5) ) High productivity and low price.

Until now, magnetic memories and semiconductor memories made of magnetic materials or semiconductors have been the mainstream, but in recent years, along with the progress of laser technology, it is inexpensive and expensive to use organic thin films such as organic dyes and photopolymers. Optical memory devices using high density recording media have 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 (Gie Winig et al., Fervetica Physika Actor, 55 , 726 (198).
2). ), It becomes possible to measure real space images with high resolution regardless of whether it is a single crystal or an amorphous material. Moreover, it has the advantage that it can be observed with low power without damaging the medium with an electric current. Since it can be operated, a wide range of applications are expected.

Such an STM utilizes that a tunnel current flows when a voltage is applied between a metal probe (probe electrode) and a conductive substance to bring them close to a distance of about 1 nm. This current is very sensitive to changes in the distance between the two, and the surface structure in real space can be drawn by scanning the probe so that the tunnel current is kept constant. You can also read the information in.

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 sufficiently perform high-density recording / reproduction on the atomic order (a few nm). As a recording / reproducing method at this time, a method of locally changing the surface shape of the substrate electrode by applying a local electric field between the probe electrode and the substrate electrode,
A method of performing recording by changing the surface state of an appropriate recording layer by using high-energy electromagnetic waves such as particle beams (electron beams, ion beams) or X-rays and energy rays such as visible / ultraviolet light, and reproducing by STM, , A material having a memory effect on the switching characteristics of voltage / current as a recording layer, for example, a thin film layer of π-electron organic compound or chalcogenide is used for recording / recording.
A method of performing reproduction using STM has been proposed. According to this method, if the recording bit size is 10 nm, a large-capacity recording / reproduction of 10 ¹² bit / cm ² is possible.

FIG. 3 shows an example of the structure of a recording / reproducing apparatus to which the STM is applied. Hereinafter, description will be given with reference to the drawings. At the center of this figure are the substrate 101, the substrate electrode 102, and the recording layer 1.
03 is a recording medium. 201 is a probe electrode,
202 is an XY stage, 203 is a support for probe electrodes, 204 is a Z-axis linear actuator that drives the probe electrodes in the Z direction, and 205 and 206 are linear actuators that drive the XY stage in the X and Y directions, respectively.

Reference numeral 301 denotes the probe electrode 201 to the recording layer 1
This is an amplifier that detects a tunnel current flowing to the electrode layer 102 via 03. 302 is a logarithmic compressor for converting a change in tunnel current into a value proportional to the gap distance between the probe electrode 201 and the recording layer 103, and 303 is a low-pass filter for extracting the surface unevenness component of the recording layer 103. . 304 is a reference voltage V _REF and a low pass filter 303
Is an error amplifier that detects an error from the output of the Z axis linear actuator 204, and 305 is a driver that drives the Z-axis linear actuator 204. A drive circuit 306 controls the position of the XY stage. A high-pass filter 307 separates the data components.

Reference numeral 207 is a probe electrode 201 and an electrode 102.
It is a circuit for applying a pulse voltage for recording / reproducing / erasing during the period. Since the probe current changes abruptly when the pulse voltage is applied, the driver 305 controls the HOLD circuit to turn on so that the output voltage becomes constant during that time.

FIG. 4 shows a cross section of the recording medium 1 and a tip of the probe electrode 201, which is a schematic view of the main part of the recording / reproducing apparatus of the conventional example. In the figure, 401 is a data bit recorded on the recording layer 103, and 402 is an electrode layer 102 on the substrate 101.
It is a crystal grain formed when forming. This crystal grain 40
The size of 2 is 30 when a normal metal is used as the material of the electrode layer 102 and is formed by a vacuum deposition method, a sputtering method, or the like.
It is about 50 nm.

The gap between the probe electrode 201 and the recording layer 103 can be kept constant by the circuit configuration shown in FIG. That is, after detecting the tunnel current flowing between the probe electrode 201 and the recording layer 103 and passing through the logarithmic compressor 302 and the low-pass filter 303, this value is compared with a reference voltage so that this comparison value approaches zero. On the probe electrode 20
The gap between the probe electrode 201 and the recording layer 103 can be made constant by controlling the Z-axis linear actuator 204 that supports the No. 1 element.

Further, by driving the XY stage 202, the probe electrode 201 traces the surface of the recording medium, and the high frequency components of the signal at point a (FIG. 3) are separated, so that the data of the recording layer 103 is recorded. Can be detected.

FIG. 5 shows the signal intensity spectrum with respect to the frequency of the signal at point a at this time. The signal of the frequency component of f ₀ or less is due to the gradual undulation of the medium due to the warp or distortion of the substrate 101. The signal centered on f ₁ is due to the unevenness of the surface of the recording layer 103, and is mainly due to the crystal grains 402 generated when the electrode material is formed. f ₂ is a carrier wave component of recording data, and 403 is a data signal band. f ₃ is a signal component generated from the atomic and molecular arrangement of the recording layer 103. Further, f _T is a tracking signal. Although not shown in the recording / reproducing apparatus of FIG. 3, the tracking signal f _T is a signal for enabling the probe electrode 201 to track the data string, and when a step is formed on the medium or it is deviated from the track. It is realized by writing a detectable signal.

In addition to the above-described method, the substrate electrode is formed by heating the crystalline substrate in vacuum vapor deposition and utilizing the epitaxial growth that occurs on the substrate to form the substrate electrode. There are attempts from the viewpoint of forming an oriented film, and attempts to recrystallize a substrate electrode layer by heating an ordinary vapor deposition substrate.

[0015]

When the substrate electrode shown in the conventional example is used for a recording medium used in a recording / reproducing apparatus, there are the following problems.

(1) When the substrate electrode is formed by a normal vapor deposition method. In order to use the high resolution characteristic of STM to perform high density recording, it is preferable to place the data signal band 403 between f ₁ and f ₃ . In this case, a high pass filter 307 having a cutoff frequency f _C is used to separate the data components. However, the base of the signal component of f ₁ is the data signal band 4
It overlaps with 03. This is because the signal component of f ₁ is the electrode layer 1
This is due to the crystal grain 402 of No. 02, and the data recording size and the bit interval are close to 1 to 10 nm with respect to 30 to 50 nm of the crystal grain 402.

For this reason, the S / N ratio of data reproduction may be lowered.

.. The tracking signal f _T can be placed only near f ₀ . Therefore, the tracking signal f
_{Since T} has a frequency that is considerably lower than the data signal band, the tracking data tracking accuracy deteriorates. This results in a high data read error rate,
The reliability of the recording / reproducing apparatus is reduced.

(2) When the substrate electrode is formed by utilizing epitaxial growth. The method using epitaxial growth has the problems that it is difficult to keep the substrate at a high temperature and a certain constant temperature, and the usable substrate is limited to a crystalline one.

(3) When heat-treating a substrate electrode formed by a normal vapor deposition method. In this method, it was necessary to damage the substrate electrode film in order to achieve smoothness that would prevent the above problems.

That is, the object of the present invention is to
In view of the above-mentioned problems of the prior art, a recording medium which can achieve high S / N ratio and high-speed access using an amorphous carbon layer for high-density recording / reproducing, and an information processing apparatus using the same are provided. To do.

[0022]

A feature of the present invention is a recording medium used in an information processing apparatus for recording / reproducing information by detecting a current flowing through an element by a probe electrode. This is a recording medium in which an amorphous carbon layer is provided on a substrate electrode facing the probe electrode, and a recording layer having an electric memory effect is laminated on the amorphous carbon layer.

The recording layer has a film thickness of several angstroms or more and 100 angstroms or less, preferably several angstroms or more and 30 angstroms or less.

Furthermore, the recording medium is characterized in that the recording layer has a monomolecular film of an organic compound or a cumulative film obtained by accumulating the monomolecular film.

The monomolecular film or cumulative film is a film formed by the Langmuir-Blodgett method (LB method), and the organic compound has a group having a conjugated π electron system in the molecule and a σ electron level. It also features a recording medium having a holding group.

The amorphous carbon layer has a function of alleviating the unevenness existing on the surface of the substrate electrode and flattening it regardless of the material of the substrate electrode as the base. Moreover, when a monomolecular film is accumulated by the LB method to form a recording layer, a hydrophobic treatment must be performed in the case of a substrate electrode using a hydrophilic material. Since it is hydrophobic, it becomes possible to realize hydrophobicization at the same time as flattening. Amorphous carbon is a conductive material and also serves as a substrate electrode.

According to this method, the surface can be flattened regardless of the material of the substrate electrode, and the hydrophobicity can be realized at the same time. As a result, a high S / N ratio is achieved when recording / reproducing with high electrical density using a probe electrode.
In comparison, it is possible to easily provide a recording medium that can be accessed at high speed.

Further, a feature of the present invention is that the recording medium as described above, a probe electrode arranged to face the recording medium, a means for applying a voltage between the recording medium and the probe electrode, An information processing device that has at least means for detecting a tunnel current flowing between the recording medium and the probe electrode and that records or reproduces information.

The present invention will be described in detail below.

As an example of the recording medium of the present invention, its sectional view is shown in FIG. Since the substrate 101 used in the present invention is used to support the substrate electrode 102, any material may be used as long as the surface is smooth to some extent, but a substrate material that can be used slightly depending on the method of forming the substrate electrode. Is limited.

The material of the substrate electrode formed on such a substrate may be any material having high conductivity, such as Au, Pt, Ag, Pd, Al, In, Sn, Pd,
There are many materials including metals such as W and alloys thereof, graphite and silicide, and conductive oxides such as ITO, and their application to the present invention can be considered. As a method of forming an electrode using such a material, a conventionally known thin film technique is sufficient.

Regarding the formation of the amorphous carbon layer 104 in the present invention, the conventionally known thin film technique is sufficient, and the vacuum vapor deposition method (resistance heating method) and the like can be mentioned. The thickness of the amorphous carbon layer is preferably 3 nm or more, though it depends on the smoothness of the substrate electrode.

Regarding the formation of the recording layer 103 used in the present invention, a vapor deposition method, a cluster ion beam method or the like can be specifically applied, but controllability, easiness, reproducibility, and Among the known prior arts because of its smoothness, L
Method B 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 a molecular order thickness is obtained. It is possible to stably supply an organic ultra-thin film which has a smoothness that is uniform and uniform over a large area and that reflects the smoothness of the substrate electrode.

In the LB method, in a molecule having a structure having a hydrophilic site and a hydrophobic site in the molecule, when the balance between them (the amphipathic balance) is appropriately maintained,
This is a method of forming a monomolecular film or a cumulative film thereof by utilizing the fact that the molecule becomes a monomolecular layer with the hydrophilic group facing downward on the water surface.

Here, examples of the group constituting the hydrophobic moiety include various widely known saturated groups such as saturated and unsaturated hydrocarbon groups, condensed polycyclic aromatic groups and chain polycyclic phenyl groups. To be These may be used alone or in combination of two or more to form a hydrophobic site.

On the other hand, the most typical constituents of the hydrophilic part are, for example, a carboxyl group, an ester group, an acid amide group, an imide group, a hydroxyl group, and further an amino group (1,2,3 and quaternary group). ) And other hydrophilic groups. Each of these also constitutes a hydrophilic part of the above-mentioned molecule, either alone or in combination.

An organic molecule having both a hydrophobic group and a hydrophilic group in a well-balanced manner and having an insulating property can form a monomolecular film on the water surface, which is extremely advantageous for the present invention. It becomes a suitable material.

As the recording layer used in the present invention, a material having a memory switching phenomenon (electric memory effect) in current-voltage characteristics, for example, a group having a conjugated π electron system and a group having only a σ electron level is used. It is possible to use an organic monomolecular film in which molecules having both are laminated on an electrode or a cumulative film thereof. The electric memory effect is brought to a state (FIG. 7: ON state, OFF state) that shows two or more different conductivity in the state where the thin film such as the organic monomolecular film and its accumulated film is arranged between the pair of electrodes. By applying a voltage exceeding a threshold value at which transition can be performed, it is possible to reversibly transit (switch) to a low resistance state (ON state) and a high resistance state (OFF state). Further, each state can be retained (memory) without applying a voltage.

Generally, most of the organic materials exhibit an insulating property or a semi-insulating property, so that the organic materials having a group having a conjugated π electron system applicable to the present invention are remarkably diversified.

The structure of the dye having a π-electron system suitable for the present invention includes, for example, a dye having a porphyrin skeleton such as phthalocyanine and tetraphenylporphyrin, an azulene dye having a squarylium group and a croconic methine group as a binding chain, and a quinoline. , Benzothiazole, benzoxazole, and other two nitrogen-containing heterocycles linked by a squarylium group and a croconic methine group, or a similar cyanine dye, or a condensed polycyclic aromatic ring such as a cyanine dye, anthracene, or pyrene, and an aromatic ring And a chain compound obtained by polymerizing a heterocyclic compound and a polymer of a diacetylene group, further, a derivative of tetracyanoquinodimethane or tetrathiafulvalene, an analog thereof and a charge transfer complex thereof, and further ferrocene, a trisbipyridine ruthenium complex Etc. Metal complex compounds.

Examples of the polymer material 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. .

Specific examples include the following molecules and the like. <Organic material> [I] Croconic methine dye

[0044]

[Chemical 1]

[0045]

[Chemical 2]

[0046]

[Chemical 3]

[0047]

[Chemical 4]

[0048]

[Chemical 5]

[0049]

[Chemical 6]

[0050]

[Chemical 7]

[0051]

[Chemical 8]

[0052]

[Chemical 9]

[0053]

[Chemical 10]

[0054]

[Chemical 11] Here, R ₁ is equivalent to the group having the above-mentioned σ electron level, and is a long-chain alkyl group introduced for facilitating the formation of a monomolecular film on the water surface. n ≦
30 is preferred. [II] Squalylium dye A compound in which the croconic methine group of the compound described in [I] is replaced with a squarylium group having the following structure.

[0055]

[Chemical 12]

[0056]

[III] Porphyrin-based dye compound

[0057]

[Chemical 14]

[0058]

[Chemical 15] R is introduced to facilitate the formation of a monomolecular film, and is not limited to the substituents listed here. Also, R ₁
˜R ₄ and R correspond to the group having the σ electron level described above. [IV] Fused polycyclic aromatic compound

[0059]

[Chemical 16]

[0060]

[Chemical 17]

[0061]

[Chemical 18]

[0062]

[Chemical 19] [V] Diacetylene compound

[0063]

[Chemical 20] X is a hydrophilic group, and -COOH is generally used, but -O
H, -CONH _2, etc. can be used. [VI] Other

[0064]

[Chemical 21]

[0065]

[Chemical formula 22]

[0066]

[Chemical formula 23]

[0067]

[Chemical formula 24]

[0068]

[Chemical 25]

[0069]

[Chemical formula 26] <Organic polymer material>

[0070]

[Chemical 27]

[0071]

[Chemical 28] Here, R ₁ is a long-chain alkyl group introduced for facilitating formation of a monomolecular film on the water surface, and its carbon number n is 5 ≦ n.
≦ 30 is preferable. R ₅ is a short chain alkyl group, and the carbon number n is preferably 1 ≦ n ≦ 4. Polymerization degree m is 1
00 ≦ m ≦ 5000 is preferable.

It is needless to say that the compounds mentioned as specific examples above have only basic structures, and various substitution products of these compounds are also suitable in the present invention. Needless to say, other than the above, any organic material or organic polymer material suitable for the LB method is suitable for the present invention. For example,
Biomaterials (for example, bacteriorhodopsin and cytochrome C), synthetic polypeptides (PBLG), and the like, which have been actively researched in recent years, are also applicable.

The electric memory effect of these compounds having the conjugated π-electron system has been observed at a film thickness of several tens of μm or less. However, since the tunnel current flowing between the probe electrode and the substrate electrode is used during recording / reproduction. Since the distance between the probe electrode and the substrate electrode must be close so that a tunnel current flows between them, the film thickness of the recording layer of the present invention is 0. Several nm or more and 10 nm or less, preferably 0. It is several nm or more and 3 nm or less.

Any material may be used as the material of the probe electrode 201 as long as it exhibits conductivity. For example, Pt,
Pt-Ir, W, Au, Ag etc. are mentioned. The tip of the probe electrode 201 needs to be as sharp as possible in order to improve the resolution of recording / reproducing / erasing. In the present invention, the probe electrode 201 is manufactured by controlling the tip shape of the needle-shaped conductive material using the electropolishing method, but the manufacturing method and shape of the probe electrode 201 are not limited thereto. .

Furthermore, the number of probe electrodes 201 is not limited to one, and a plurality of probe electrodes may be used, such as one for position detection and one for recording / reproduction. Recording and reproduction are performed by applying a voltage from the probe electrode 201 to the recording layer 103.

FIG. 2 shows the frequency spectrum of the signal at point a in FIG. 3 showing the information processing apparatus according to the present invention. The signal of the frequency component of f ₀ or less is due to the gradual undulation of the medium due to the warp or distortion of the substrate 101. f ₂ is a carrier wave component of recording data, and 403 is a data signal band. f
₃ is a signal component generated from the atomic and molecular arrangement of the recording layer 103. Further, f _T is a tracking signal. The signal centered on f ₁ reflects slight irregularities on the surface of the substrate, and the substrate is prepared such that the irregularities are equal to or smaller than the recording signal of data. The change in the unevenness is 1 nm or less in the recording / reproducing using the STM. Further, in the recording medium according to the present invention, the recording layer 103
The size of the smooth surface is 1 μm square or more.

By using this and the recording medium in which the amorphous carbon layer is provided on the substrate electrode, the following operational effects are obtained. ． The signal component f ₁ due to the unevenness of the surface of the recording layer 103 and the data signal band 403 do not overlap with _each other, and the S / N is not reduced due to the spread of the spectrum of f ₁ . That is, the data error rate can be reduced. ． The tracking signal f _T can be placed near the data signal band 403. That is, the tracking signal f _T
Since a high frequency can be taken, it is possible to sufficiently secure the tracking accuracy of tracking. ． Since the frequency of the tracking signal f _T is high, when the groove for tracking is formed on the recording medium, the shape may be almost the same as the size of the data bit 401.
Tracking can be performed without sacrificing recording density. ． Since there is no unevenness on the surface of the recording layer 103, the recording layer 103
X while keeping the gap between the surface and the probe electrode 201 constant
The displacement of the probe electrode 201 on the Z axis is small when performing Y scanning. Therefore, the XY stage can be driven at an extremely high speed. ． Since there is no unevenness on the surface of the recording layer 103, the tip of the probe electrode 201, that is, the position of the tip atom through which the tunnel current flows is stably selected. The recording layer 1 having irregularities
03, a ghost phenomenon in which a tunnel current flows between the plurality of atoms of the probe electrode 201 and the recording layer 103 disappears. ． In vacuum deposition of substrate electrodes, compared to the method of heating a crystalline substrate and forming a substrate electrode by using epitaxial growth on such a substrate, no complicated steps are required, and it is used for substrates other than crystalline substrates. can do.

[0078]

EXAMPLES The present invention will be described below with reference to examples.

Example 1 An optically polished glass substrate (# 7059 manufactured by Corning Incorporated) was washed with a neutral detergent and trichlene to obtain a substrate 101. Then, the substrate 10
A 100 nm-thick ITO film was formed on 1 by sputtering to form a substrate electrode 102. Further, carbon was deposited on the ITO substrate electrode by a vacuum vapor deposition method (resistance heating). As a result, carbon was formed into an amorphous film on the ITO electrode, and the amorphous carbon layer 104 was formed. The thickness of the amorphous carbon layer is 5 nm and 10 n
Three types of m and 20 nm were deposited. The nature of the ITO surface was originally hydrophilic, but it was hydrophobic due to the amorphous carbon film. This eliminates the need for the conventional hydrophobizing treatment. Using this substrate as a carrier, a polyimide (hereinafter abbreviated as PI) monomolecular film is accumulated by the following LB method,
This was used as the recording layer 103.

The method of forming this LB film will be described below.

The polyamic acid represented by the formula (29) (hereinafter referred to as PA
Is abbreviated) in an N, N-dimethylacetamide-benzene mixed solution (1: 1 V / V) (concentration of monomer conversion: 1 × 10 ⁻³ M), and then separately adjusted N, N-dimethyloctadecylamine 1: 2 with 1 × 10 ⁻³ M of the same solvent of
It was mixed with (V / V) to prepare a polyamic acid octadecylamine salt solution shown in Chemical formula 30. 2 such solution
After spreading on pure water at 0 ° C. to evaporate and remove the solvent from the water surface, the surface pressure was increased to 25 mN / m to form a monomolecular film on the water surface.

Next, while keeping the surface pressure constant,
The substrate was gently dipped at a speed of 5 mm / min so as to traverse the water surface, and the pulling operation was further repeated to accumulate four layers of Y-shaped monomolecular film. Finally, the substrate is heated to 300 ° C
The PA cumulative film was imidized by performing heat treatment for 10 minutes at (Formula 31) to form a PI thin film to be the recording layer 103, and a recording medium 1 was obtained.

[0083]

[Chemical 29]

[0084]

[Chemical 30]

[0085]

[Chemical 31] Next, the recording medium manufactured by the method described above was placed on the XY stage 202 of the information processing apparatus shown in FIG. 3, and the surface shape was examined using the platinum / rhodium probe electrode 201. Reflects the smoothness of the amorphous carbon layer, and the recording medium having an amorphous carbon layer film thickness of 20 nm had surface irregularities of 1 nm or less at 10 μm square (other recording media showed slight irregularities). ).

That is, it was confirmed that the irregularities of several nm to several tens nm existing in the crystal grain boundary portion of the ITO substrate electrode were alleviated by the amorphous carbon layer and the smoothness was improved.

Next, the thickness of the amorphous carbon layer is 2
Recording / reproducing / erasing experiments were performed on a 0 nm recording medium. Probe electrode 201 and electrode layer 102 of recording medium
A voltage of + 1.5V was applied between the two electrodes and the distance (Z) between the probe electrode 201 and the surface of the recording layer 103 was adjusted while monitoring the current. At this time, the probe current I _P for controlling the distance Z between the probe electrode 201 and the surface of the recording layer 103 was set so that 10 ⁻¹⁰ A ≧ I _P ≧ 10 ⁻¹¹ A.

Next, information was recorded at a pitch of 10 nm while scanning the probe electrode 201. To record such information, the probe electrode 201 is on the + side and the electrode layer 102 is on the − side, and the electric memory material (polyimide LB film 4) is used.
A rectangular pulse voltage equal to or higher than the threshold voltage V _th ON shown in FIG. 6 at which the layer) changes to a low resistance state (ON state) was applied. Then, the probe electrode 201 was returned to the recording start point, and the recording layer 103 was scanned again. At this time, when reading the record, adjustment was made so that Z = constant. As a result, it was shown that a probe current of about 10 nA flows in the recorded bit and is in the ON state.

The threshold voltage V _th O at which the electric memory material changes from the ON state to the OFF state is set as the probe voltage.
As a result of setting the voltage to 10 V which is higher than FF and tracing the recording position again, it was also confirmed that all the recording states were erased and transitioned to the OFF state.

Example 2 Three kinds of recording media 1 were produced in exactly the same manner as in Example 1 except that the material of the substrate electrode 102 formed by vacuum vapor deposition was changed to Ag. However, the nature of the Ag surface was originally hydrophilic, but it was hydrophobic due to the formation of the amorphous carbon layer, and therefore the hydrophobic treatment could be omitted.

Next, the surface irregularities of the recording medium were examined in the same manner as in Example 1. As for all the amorphous carbon layer thicknesses of 5 nm, 10 nm and 20 nm, the irregularities on the surface were 1 nm at 10 μm square. It was below.

Further, when an experiment of recording / reproducing / erasing was conducted, the same results as in Example 1 were obtained.

(Example 3) Three kinds of recording media 1 were produced in exactly the same manner as in Example 1 except that the material of the substrate electrode 102 formed by vacuum vapor deposition was changed to Au. However, at this time, in order to improve the adhesion between Au and the substrate, a Cr layer having a film thickness of 5 nm is formed as a subbing layer of Au by a vacuum deposition method.

Next, the surface irregularities of the recording medium were examined in the same manner as in Example 1. As for all the amorphous carbon layer thicknesses of 5 nm, 10 nm and 20 nm, the irregularities of the surface were 1 nm at 10 μm square. It was below.

Further experiments were conducted on recording, reproduction and erasing, and the same results as in Example 1 were obtained.

According to the above-mentioned examples, by providing the amorphous carbon layer on the substrate electrode, the flatness of the substrate electrode can be improved and the hydrophobic surface can be maintained. It has become possible to easily provide a recording medium that can obtain a high S / N ratio and high-speed access in an information processing apparatus that performs recording / reproduction and the like.

However, the film thickness of the amorphous carbon layer to be formed needs to be changed depending on the material of the substrate electrode, the film forming method, the film forming conditions and the like. This is because the film thickness of the amorphous carbon layer required for flattening differs depending on the unevenness present on the surface of the substrate electrode.

Although the LB method is used for forming the recording layer in the above-mentioned embodiments, any film forming method capable of forming an extremely thin and uniform film can be used without being limited to the LB method. Specifically, a film forming method such as MBE or CVD method can be used. Further, the present invention does not limit the substrate material and its shape. Further, in the present embodiment, the probe electrode is one, but the recording / reproducing electrode and the tracking electrode may be divided into two or more.

[0099]

As described above, according to the present invention, the flatness of the substrate electrode is improved and the hydrophobic surface is maintained by providing the amorphous carbon layer having an appropriate film thickness on the substrate electrode. Therefore, various substrates and various substrate electrode materials can be freely selected. Therefore, a high S / N ratio and high-speed access can be obtained in an information processing device that uses a probe electrode to perform electrical high-density recording / reproducing.

[Brief description of drawings]

FIG. 1 is a schematic view of a probe electrode and a main part of a recording medium in an information processing apparatus according to the present invention.

FIG. 2 is a diagram of a frequency spectrum of a reproduction signal of the present invention.

FIG. 3 is a configuration example of an information processing apparatus according to the present invention to which STM is applied.

FIG. 4 is a schematic diagram of a main part of a recording / reproducing apparatus of a conventional example.

FIG. 5 is a diagram of a frequency spectrum of a reproduction signal of a conventional example.

FIG. 6 is a waveform diagram of a pulse voltage applied when recording is performed on the recording medium of the present invention.

FIG. 7 is a diagram showing an electric memory effect of the recording layer used in the present invention.

[Explanation of symbols]

101 substrate 102 substrate electrode 103 recording layer 104 amorphous carbon layer 201 probe electrode 202 XY stage 203 probe electrode support 204 Z-axis linear actuator 205 X-axis linear actuator 206 Y-axis linear actuator 207 Pulse voltage application circuit 301 amplifier 302 logarithmic compressor 303 low pass filter 304 Error amplifier 305 driver 306 XY stage position control drive circuit 307 High pass filter 401 data bits 402 crystal grains 403 data signal band

Claims (6)

[Claims] 1. A recording medium used in an information processing device for recording / reproducing information by detecting a current flowing through an element by a probe electrode, wherein an amorphous carbon layer is provided on a substrate electrode arranged to face the probe electrode. A recording medium comprising a recording layer having an electric memory effect laminated on the amorphous carbon layer. 2. The recording medium according to claim 1, wherein the film thickness of the recording layer is several angstroms or more and 100 angstroms or less. 3. The recording medium according to claim 1, wherein the recording layer has a monomolecular film of an organic compound or a cumulative film obtained by accumulating the monomolecular film. 4. The recording medium according to claim 1, wherein the recording layer is a monomolecular film of an organic compound formed by the LB method or a cumulative film obtained by accumulating the monomolecular film. 5. The recording layer has a monomolecular film of an organic compound having a group having a conjugated π electron system and a group having a σ electron level in the molecule, or a cumulative film obtained by accumulating the monomolecular film. The recording medium according to claim 1 or 2, characterized in that: 6. A recording medium according to any one of claims 1 to 5, and a probe electrode arranged to face the recording medium.
Means for applying a voltage between the recording medium and the probe electrode,
An information processing apparatus, comprising at least means for detecting a tunnel current flowing between the recording medium and a probe electrode, for recording, reproducing or erasing information.