JP2748182B2 - Recording medium, method of manufacturing the same, recording method, recording / reproducing method, recording device, reproducing device, recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a recording medium applying a tunnel current generated by applying a voltage between a probe electrode, which is a probe of a conductive material, and a conductive substance, and manufacturing the recording medium. The present invention relates to a method, a recording method using such a recording medium, a recording / reproducing method, a recording device, a reproducing device, and a recording / reproducing device.

[Prior Art] In recent years, with the development of the information-oriented society, development of a large-capacity memory technology has been performed. Recently, a recording / reproducing apparatus using a scanning tunneling electron microscope (hereinafter abbreviated as STM) has appeared (for example, JP-A-61-80536). Such STM
Utilizes the fact that a tunnel current flows when a voltage is applied between a probe (probe electrode) made of a conductive material and a conductive material to approach a distance of about 1 nm. This current is very sensitive to changes in the distance between them. By scanning the probe electrode 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 / reproducing on the order of atoms (sub-nanometer).

Regarding the recording / reproducing method of memory using STM, the detected tunnel current value is averaged and servo is applied, so that the probe can be operated at high speed without changing the distance (Z) between the probe electrode and the recording surface much. (Japanese Utility Model Application Laid-Open No. 1-13).
No. 3239).

In this method, when scanning the surface of the recording layer with a probe, the probe scanning speed is increased by reducing the amount of displacement of the spatial position of the probe according to the surface irregularities in the Z-axis direction, thereby greatly improving the reproduction speed. It is a thing.

STM is used for recording and playback using a material that has a memory effect on the switching characteristics of voltage and current, such as a π-electron organic material or a thin film layer of chalcogen compounds as the recording layer.
(For example, JP-A-63-161552). According to this method, large-capacity recording and reproduction of 10 ¹² bits / cm ² is possible if the recording bit size is 10 nm.

FIG. 2 shows a cross-sectional example of a conventional recording medium. 105 is a track, 106 is a groove having a track (track groove), 102 is a metal electrode and a recording layer, and 101 is a smooth substrate. Reference numeral 104 denotes a recording surface. The recording medium used here must have a track. When there is no track, recording and reproduction become very difficult.

The track indicates the step portion of the unevenness, and the depth of the track groove was about 50 ° to 100 ° from the electrode surface.

With such a track groove depth, a tunnel current between the recording surface 104 and the recording surface 104 can be detected. It is difficult to detect the tunnel current from the bottom of the track groove.

In such a configuration, if the probe electrode is positioned above the track groove while maintaining the position of the Z-axis spatial coordinate at the time of recording / reproducing, that is, if a tracking error occurs, a current is detected by the probe. Therefore, there is a high possibility that feedback in the Z-axis direction is not applied. In order to always provide feedback, it is necessary to detect the current by the probe regardless of the position of the probe.

[Problems to be Solved by the Invention] In view of the above-mentioned problems of the prior art, an object of the present invention is to provide a structure in which even when a probe electrode is displaced from above a recording surface and positioned above a track groove, a tunnel current is reduced. And keep the feedback in the Z-axis direction.
Recording that can prevent the contact of the probe electrode with the recording surface, the recording surface due to the contact of a part of the track groove, the damage of the probe electrode, etc. by always detecting the height information of the Z-axis of the probe electrode. It is an object of the present invention to provide a recording medium which is a medium and which enables high-speed recording and reproduction, a recording apparatus using the recording medium as described above, a reproducing apparatus, a recording and reproducing apparatus, and a method for manufacturing such a recording medium. is there.

[Means and Actions for Solving the Problems] The features of the present invention are as follows. First, in a recording medium on or from which information is recorded or reproduced by applying a voltage from a probe electrode, On the surface on the side facing the probe electrode, formed is a smooth surface having a height difference of 1 nm or less and a track groove formed adjacent to the smooth surface and formed concavely with respect to the smooth surface. An electrode layer; and a recording layer formed on a smooth surface of the electrode layer and having a property that transitions between two or more states having different conductivity by applying a voltage. Is a recording medium characterized by having a length of 20 mm.

Second, in a method for manufacturing a recording medium having a track on which information is recorded or reproduced by applying a voltage from a probe electrode, a base material having a smooth surface with a difference in height of unevenness of 1 nm or less is prepared. A step of forming an organic thin film having a thickness of 20 ° or less on a smooth surface of the base material, and patterning the organic thin film to leave a convex portion having a shape corresponding to the track, thereby forming the base material. Exposing a smooth surface, forming an electrode layer on the smooth surface and the projections of the base material, and bonding a substrate to a surface of the electrode layer opposite to a surface in contact with the base material. Transferring the electrode layer to the substrate by peeling the electrode layer from the base material, and applying a voltage to the surface of the electrode layer transferred to the substrate that is in contact with the smooth surface and the convex portion of the base material. Different conductivity by applying Its characteristics between two or more states are producing method of a recording medium, characterized in that comprising the step of forming a recording layer of transition.

Third, while using the recording medium of the first invention, the surface of the recording layer of the recording medium is relatively scanned by a probe electrode disposed close to the surface, the distance between the electrode layer and the probe electrode is increased. Applying a bias voltage to the recording medium to identify a track of the recording medium by detecting a tunnel current flowing through the probe electrode, and recording information by applying a pulse voltage between the electrode layer and the probe electrode. This is a characteristic recording method.

Fourth, using the recording medium according to the first aspect of the invention, the surface of the recording layer of the recording medium is relatively scanned by a probe electrode disposed close to the surface, and the surface of the recording layer is interposed between the electrode layer and the probe electrode. A bias voltage is applied to detect a track of the recording medium by detecting a tunnel current flowing through a probe electrode, and information is recorded by applying a pulse voltage between the electrode layer and the probe electrode, thereby recording information. A bias voltage is applied between the electrode layer and the probe electrode while relatively scanning the surface of the recording layer on which is recorded by the probe electrode disposed close to the surface, and a tunnel current flowing through the probe electrode is detected. And reproducing the information by performing the operation.

Fifth, the recording medium according to the first aspect of the invention, a probe electrode disposed in proximity to the surface of the recording layer of the recording medium, a scanning unit configured to scan the probe electrode relative to the recording medium, An identification circuit that identifies a track of the recording medium by applying a bias voltage between the electrode layer of the recording medium and the probe electrode and detects a tunnel current flowing through the probe electrode; And a recording circuit for recording information by applying a pulse voltage between the recording device and the recording circuit.

Sixth, the recording medium according to the first aspect of the invention, a probe electrode disposed close to a surface of a recording layer of the recording medium, scanning means for scanning the probe electrode relative to the recording medium, A bias voltage is applied between the electrode layer of the recording medium and the probe electrode, and a reproducing circuit that reproduces information recorded on the recording layer of the recording medium by detecting a tunnel current flowing through the probe electrode. It is a reproducing apparatus characterized by the following.

Seventh, the recording medium according to the first aspect of the invention, a probe electrode arranged in proximity to the surface of the recording layer of the recording medium, a scanning unit for relatively scanning the probe electrode with respect to the recording medium, An identification circuit that identifies a track of the recording medium by applying a bias voltage between the electrode layer of the recording medium and the probe electrode and detects a tunnel current flowing through the probe electrode; A recording circuit for recording information by applying a pulse voltage between the recording medium and a bias voltage between the electrode layer of the recording medium and the probe electrode, and detecting a tunnel current flowing through the probe electrode. This is a recording / reproducing apparatus including a reproducing circuit for reproducing information recorded on a recording layer of a recording medium.

 Hereinafter, the configuration and operation of the present invention will be described.

FIG. 1 shows a recording medium according to one embodiment of the present invention. 105 is a track, 106 is a groove having a track (track groove), 102 is a metal electrode and a recording layer, and 101 is a substrate. Reference numeral 104 denotes a recording surface corresponding to a recording position.

Here, the track groove 106, which is a feature of the present invention, is preferably as shallow as possible, and a preferable depth is a region where a tunnel current can be detected from the surface of the conductive material layer.
It varies slightly depending on the work function of the conductive material, the bias voltage, and the like. The distance is at most about several nm, but the distance is 20 ° or less from the viewpoint of the current detection method and the like.

Next, another recording medium according to the present invention is shown in FIG. In the present invention, the metal electrode 102 'and the recording layer 103 are separate from the recording medium shown in FIG. The feature of this configuration is that the recording layer 103 is not limited to a conductive material, and a layered organic thin film or the like can be used. In this case, the thickness of the thin film is 4 to 20 mm.
Within this range (when the applied voltage is 0.1 to 10 V), a tunnel current can be obtained between both electrodes.

Next, a recording / reproducing apparatus using the above-described recording medium will be described. FIG. 4 is a schematic configuration diagram of such an apparatus.

Here, a configuration is provided in which a recording medium of a type in which a metal electrode layer 102 ′ is provided on a substrate 101 and a recording layer 103 is further provided thereon. 201 is an XY stage, 202 is a probe electrode, 203 is a support for the probe electrode, 204 is a linear actuator for driving the probe electrode in the Z direction, 205 and 206 are linear actuators for driving the XY stage in the X and Y directions, 207 Is a pulse voltage circuit. An amplifier 301 detects a current flowing from the probe electrode to the electrode layer 102 'via the recording layer 103. Reference numeral 302 denotes a logarithmic compressor for converting a change in current into a value proportional to the distance between the probe electrode and the recording layer, and reference numeral 303 denotes a low-pass filter for extracting a surface unevenness component of the recording layer. 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. 306 is a drive circuit for controlling the position of the XY stage, and 307 is a high-pass filter for separating data components.

Needless to say, a configuration including the other recording medium described above is also possible. Furthermore, although the recording / reproducing / erasing device has been described here, the present invention can also be configured as a recording device, a reproducing device, or the like.

Next, a method for manufacturing a recording medium according to the present invention will be described. First, as shown in FIG. 5 (b), an amphiphilic organic material having sensitivity to energy rays such as electric rays is coated on a substrate 107 having extremely good smoothness such as a fused quartz or mica substrate by Langmuir Blodget. The thin film 108 is formed by a method (LB method). The film formed by the LB method is called an LB film. Then (c)
After irradiation with energy rays in a pattern as shown in FIG. Next, as shown in (d), a metal electrode layer 102 is formed on the patterned substrate by a normal vacuum deposition method, a sputtering method, or an epitaxial growth method. Next, as shown in (e), an adhesive such as a polyimide-based adhesive, an epoxy-based adhesive, a cyanoacrylate-based adhesive, or the like is applied to the substrate to be peeled (the substrate 101 on which the electrodes are formed), and then adhered to the electrode surface Let it. Next, as shown in (f), the metal substrate is peeled off and the metal electrode is peeled off from the smooth substrate to obtain an electrode substrate (recording medium).

Next, a recording layer is formed using this electrode substrate as shown in FIG. The organic material used for the recording layer and the forming method are described below.

As an organic thin film material, 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 formed on an electrode. It is possible to use an organic monomolecular film or a cumulative film thereof laminated on the substrate. The electric memory effect is a state in which a thin film such as the above-mentioned organic monomolecular film and its cumulative film is disposed between a pair of electrodes, and shows a state showing two or more different electric conductivities (FIG. 7 ON state, OFF state). A low-resistance state (ON state) and a high-resistance state (OF
(F state).
In addition, each state can be retained (memory) without applying a voltage.

In general, most of organic materials exhibit insulating or semi-insulating properties, and therefore, in the present invention, the organic materials having a group having an applicable π-electron level are extremely wide-ranging. Examples of the structure of the dye having a π-electron system suitable for the present invention include, 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 binding chain, quinoline, and 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 Is a chain compound and a polymer of a diacetylene group, furthermore, a derivative of tetracyanoquinodimethane or tetrathiafulvalene and an analog thereof and a charge transfer complex thereof, and further, a metal complex such as ferrocene and trisbipyridine ruthenium complex. Compound And the like.

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.

With respect to the formation of the organic recording layer, specifically, a vapor deposition method, a cluster ion beam method, or the like can be applied.However, among known conventional techniques from the viewpoint of controllability, easiness and reproducibility, LB is used.
The method is very 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 of two or more thereof. On the other hand, the most typical components of the hydrophilic site are, for example, a carboxyl group, an ester group,
Examples thereof include acid amide groups, imide groups, hydroxyl groups, and hydrophilic groups such as amino groups (1, 2, tertiary and quaternary).

Each of these may be used alone or in combination with a plurality thereof to constitute the hydrophilic portion of the molecule.

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.

On the other hand, an electrode having a smooth surface can be formed by peeling off the electrode deposited on a smooth substrate in this process and transferring it to another substrate. The electrode surface reflects the smooth surface of the substrate, and the surface of the obtained electrode substrate can be equivalent to the smooth substrate surface.

According to the manufacturing method as described above, a track groove shallower than the conventional one can be formed in the electrode layer, and it becomes possible to finally detect a tunnel current from the groove bottom.

[Example] Hereinafter, an example of the present invention will be described.

Example 1 In this example, a recording medium of the type shown in FIG. 1 was manufactured. First, polyisobutyl methacrylate (PIBM) was coated on a fused silica substrate by the Langmuir-Blodgett method (LB).
Method) to deposit one layer. The thickness of one layer was about 10 °.

The method for forming a PIBM monolayer is described below. PI
BM was dissolved in chloroform to adjust the concentration to 1 g /.
This solution was developed on an aqueous phase composed of pure water at a water temperature of 20 ° C. to form a monomolecular film on the water surface. Increase surface pressure to 12mN / m,
The washed fused quartz substrate previously immersed in the aqueous phase was pulled up at a speed of 5 mm / min to form a PIBM monomolecular film.

An EB exposure apparatus (ELIONICS ELS-330)
According to 0), writing was performed at an acceleration voltage of 30 kV and a dose of 100 μC / cm ² . Development was performed with isopropyl alcohol / water (85/15). Subsequently, a film having a thickness of 1500 Å was formed by a vacuum deposition method at a deposition rate of 25 Å / sec. Then, an adhesive (KONISHI BOND HIGH TEMP H) is attached to the glass substrate (Corning # 7059).
A small amount of T-10) was applied and adhered to the Au surface of the substrate on which Au was deposited. The contact pressure was maintained at about 0.5 kg / cm ^2, and the mixture was left for 2 days while heating to 120 ° C. When the two substrates were peeled off, a recording medium having patterned tracks was obtained while maintaining the surface states of the fused quartz substrate and the patterned PIBM monomolecular film.

The observation was performed by using STM. The truck had the width as set. The track groove depth was about 8 °. When the probe was scanned in the same manner as recording and playback using STM with the probe's Z-axis direction feedback control moderated and the probe's Z-axis displacement reduced against the detected change in the current value. Even when the probe came to the position of the track groove, the current could be detected by the probe.

Example 2 In this example, a recording medium of the type shown in FIG. 1 was manufactured. First, polyisobutyl methacrylate (PIBM) was coated on a fused silica substrate by the Langmuir-Blodgett method (LB).
Method) to deposit two layers. The thickness of one layer was about 10 °.

The method for forming a PIBM monolayer is described below. PI
BM was dissolved in chloroform to adjust the concentration to 1 g /.
This solution was developed on an aqueous phase composed of pure water at a water temperature of 20 ° C. to form a monomolecular film on the water surface. Increase surface pressure to 12mN / m,
The washed fused quartz substrate previously immersed in the aqueous phase was pulled up at a speed of 5 mm / min to form a PIBM monomolecular cumulative film.

An EB exposure apparatus (ELIONICS ELS-330)
According to 0), writing was performed at an acceleration voltage of 30 kV and a dose of 100 μC / cm ² . Development was performed with isopropyl alcohol / water (85/15). Subsequently, a film having a thickness of 1500 Å was formed by a vacuum deposition method at a deposition rate of 25 Å / sec. Then, an adhesive (KONISHI BOND HIGH TEMP H) is attached to the glass substrate (Corning # 7059).
A small amount of T-10) was applied and adhered to the Au surface of the substrate on which Au was deposited. The contact pressure was maintained at about 0.5 kg / cm ^2, and the mixture was left for 2 days while heating to 120 ° C. When the two substrates were peeled off, a recording medium having patterned tracks was obtained while maintaining the surface states of the fused quartz substrate and the patterned PIBM monomolecular film.

The observation was performed by using STM. The truck had the width as set. The track groove depth was about 18 mm. When the probe was scanned in the same manner as recording and playback using STM with the probe's Z-axis direction feedback control moderated and the probe's Z-axis displacement reduced against the detected change in the current value. Even when the probe came to the position of the track groove, the current could be detected by the probe.

Example 3 In this example, a recording medium of the type shown in FIG. 1 was manufactured. First, using a polyamic acid (PAAD-DDE / PAA) obtained by polymerizing 4,4'-diaminodiphenyl ether and pyromellitic anhydride, a two-layer monomolecular cumulative film is formed on a fused quartz substrate by a Langmuir-Blodgett method. Was formed. The thickness of one layer was about 15 °.

Hereinafter, a method of forming a monolayer of PAAD-DDE / PAA will be described. Dimethylacetamide of PAAD-DDE / PAA (DMA
C) PAAD-DDE in solution (concentration in terms of monomer 1 × 10 ^-3 mol /)
N, N-dimethylhexadecylamine (DHDA) was added at a ratio of 2 to 1 equivalent of the repeating unit of / PAA, and PAAD-DDE /
A PAA / DHDA solution was prepared. This solution was developed on an aqueous phase composed of pure water at a water temperature of 20 ° C. to form a monomolecular film on the water surface.

An LB exposure system (ELIONICS ELS-330)
According to 0), writing was performed at an acceleration voltage of 30 kV and a dose of 60 μC / cm ² . The film was developed by DMAC and baked at 150 ° C. for 2 hours to imidize the polyamic acid to obtain a polyimide (PI-DDE / PAA). The thickness of the polyimide obtained at this time was about 5 ° per layer.

Subsequently, a film having a thickness of 1500 Å was formed by a vacuum deposition method at a deposition rate of 25 Å / sec. After this, the glass substrate (Corn
ing # 7059) with adhesive (KONISHI BOND HIGH TEMP HT-1)
A small amount of 0) was applied and adhered to the Au surface of the substrate on which Au was deposited. The contact pressure was maintained at about 0.5 kg / cm ^2, and the mixture was left for 2 days while heating to 120 ° C. When the two substrates were peeled off, a recording medium having patterned tracks was obtained while maintaining the surface condition of the fused quartz substrate and the patterned polyimide LB film.

The observation was performed by using STM. The truck had the width as set. The track groove depth was about 8 °. When the probe was scanned in the same manner as recording and playback using STM with the probe's Z-axis direction feedback control moderated and the probe's Z-axis displacement reduced against the detected change in the current value. Even when the probe came to the position of the track groove, the current could be detected by the probe.

Example 4 In this example, a recording medium of the type shown in FIG. 1 was manufactured. First, using a polyamic acid (PAAD-DDF / PAA) obtained by polymerizing 4,4'-diaminodiphenyl ether and pyromellitic anhydride, a two-layer monomolecular cumulative film is formed on a fused quartz substrate by a Langmuir-Blodgett method. Was formed. The thickness of one layer was about 15 °.

Hereinafter, a method for preparing a monolayer of PAAD / DDE / PAA will be described. Dimethylacetamide (DMAC) of PAAD-DDE / PAA
PAAD-DDE / PA in solution (concentration of monomer 1 × 10 ^-3 mol /)
N, N-dimethylhexadecylamine (DHDA) was added at a ratio of 2 to 1 equivalent of the repeating unit of A, and PAAD-DDE / PAA /
A DHDA solution was prepared. This solution was developed on an aqueous phase composed of pure water at a water temperature of 20 ° C. to form a monomolecular cumulative film on the water surface.

The surface pressure was increased to 25 mN / m, and the washed fused quartz substrate previously immersed in the aqueous phase was immersed at a speed of 5 mm / min and pulled up to form a PAAD-DDE / PAA monomolecular cumulative film.

An EB exposure apparatus (ELIONICS ELS-330)
According to 0), writing was performed at an acceleration voltage of 30 kV and a dose of 60 μC / cm ² . The portion exposed to the electron beam was subjected to imidization to form polyimide (PI-DDE / PAA). The thickness of the polyimide obtained at this time was about 5 ° per layer. An organic monomolecular film having a step was obtained.

Subsequently, a film having a thickness of 1500 Å was formed by a vacuum deposition method at a deposition rate of 25 Å / sec. After this, the glass substrate (Corn
ing # 7059) with adhesive (KONISHI BOND HIGH TEMP HT-1)
A small amount of 0) was applied and adhered to the Au surface of the substrate on which Au was deposited. The contact pressure was maintained at about 0.5 kg / cm ^2, and the mixture was left for 2 days while heating to 120 ° C. When the two substrates were peeled off, a recording medium having patterned tracks was obtained while maintaining the surface condition of the fused quartz substrate and the patterned polyimide LB film.

The observation was performed by using STM. The truck had the width as set. The track groove depth was about 10 mm. When the probe was scanned in the same manner as recording and playback using STM with the probe's Z-axis direction feedback control moderated and the probe's Z-axis displacement reduced against the detected change in the current value. Even when the probe came to the position of the track groove, the current could be detected by the probe.

Example 5 The deposition rate of Au in Example 1 was changed from 25 ° / sec to 1 ° / sec.
And carried out in the same manner as in Example 1. As a result, Example 1
And similar results were obtained.

Example 6 The adhesive in Example 1 was replaced with Konishi Bond High Temp HT-10.
And a 10-hour curable two-liquid mixed epoxy adhesive (KONISHIBON E set) was used in the same manner as in Example 1. As a result, the same result as in Example 1 was obtained.

Example 7 The same operation as in Example 1 was performed, except that mica was used instead of the fused quartz substrate used in Example 1. As a result, the same result as in Example 1 was obtained.

Example 8 Polyisobutyl methacrylate (PIBM) was coated on a fused quartz substrate by the Langmuir Project method (LB method).
Layers were deposited. The thickness of one layer was about 10 °.

The method for forming a PIBM monolayer is described below. PI
BM was dissolved in chloroform to adjust the concentration to 1 g /.
This solution was developed on an aqueous phase composed of pure water at a water temperature of 20 ° C. to form a monomolecular film on the water surface. Increase surface pressure to 12mN / m,
The washed fused quartz substrate previously immersed in the aqueous phase was pulled up at a speed of 5 mm / min. To form a PIBM monomolecular film.

An ultraviolet light exposure device (PLA-521F manufactured by Canon Inc.) is applied to this thin film.
According to A), ultraviolet light having a wavelength of 250 nm was irradiated through the pattern. Development was performed with isopropyl alcohol / water (85/15). Subsequently, a film having a thickness of 1500 Å was formed by a vacuum deposition method at a deposition rate of 25 Å / sec. Thereafter, a small amount of an adhesive (Conishi Bond High Temp HT-10) was applied to a glass substrate (Corning # 7059), and was adhered to the Au surface of the substrate on which Au was deposited. The contact pressure was maintained at about 0.5 kg / cm ^2, and the mixture was left for 2 days while heating to 120 ° C. When both substrates were peeled off, a recording medium having patterned tracks was obtained while maintaining the surface state of the fused quartz substrate and the patterned PIBM monomolecular film.

The observation was performed by using STM. The truck had the width as set. The track groove depth was about 8 °. When the probe was scanned at the same time as recording and reproduction using STM with the probe's Z-axis displacement amount reduced while the probe's Z-axis displacement amount was reduced in response to the detected current value change, Even when the probe came to the position of the groove, the current could be detected by the probe.

Example 9 Polyisobutyl methacrylate (PIBM) was coated on a fused quartz substrate by the Langmuir Project method (LB method).
Layers were deposited. The thickness of one layer was about 10 °.

The method for forming a PIBM monolayer is described below. PI
BM was dissolved in chloroform to adjust the concentration to 1 g /.
This solution was developed on an aqueous phase composed of pure water at a water temperature of 20 ° C. to form a monomolecular film on the water surface. Increase surface pressure to 12mM / m,
Washed SiO ₂ (1 μm thick) previously immersed in the aqueous phase
Was lifted at a speed of 5 mm / min. To produce a PIBM monolayer.

An EB exposure apparatus (ELIONICS ELS-330)
According to 0), writing was performed at an acceleration voltage of 30 kV and a dose of 10 μc / cm ² . Development was performed with isopropyl alcohol / water (85/15). Subsequently, a film having a thickness of 1500 Å was formed by a vacuum deposition method at a deposition rate of 25 Å / sec. Then, an adhesive (KONISHI BOND HIGH TEMP H) is attached to the glass substrate (Corning # 7059).
A small amount of T-10) was applied and adhered to the Au surface of the substrate on which Au was deposited. The contact pressure was maintained at about 0.5 kg / cm ^2, and the mixture was left for 2 days while heating to 120 ° C. When both substrates were peeled off, a recording medium having patterned tracks was obtained while maintaining the surface state of the fused quartz substrate and the patterned PIBM monomolecular film.

The observation was performed by using STM. The truck had the width as set. The track groove depth was about 8 °. When the probe was scanned at the same time as recording and reproduction using STM with the probe's Z-axis displacement amount reduced while the probe's Z-axis displacement amount was reduced in response to the detected current value change, Even when the probe came to the position of the groove, the current could be detected by the probe.

Example 10 Using the recording medium obtained in Example 1, an experiment of recording and reproduction was performed.

The recording / reproducing apparatus shown in FIG. 4 was used, and a probe electrode obtained by electrolytically polishing tungsten was used. The distance (Z) between the probe electrode and the surface of the recording layer is finely controlled by a piezoelectric element so that the current is kept constant. Further, the fine movement control mechanism is 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 can directly perform recording and reproduction. The recording medium is placed on a high-precision XY stage and can be moved to any position. The above recording medium
Placed on XY stage. Next, a voltage of 1 V was applied between the probe electrode and the recording medium, and the distance (Z) between the probe electrode and the recording layer surface was adjusted while monitoring the current. In this case, setting the probe current I _P for controlling the distance Z between the probe electrode and the recording layer surface so that the _{^{10 10 A ≧ I P ≧ 10}} -11 A. Next, information was recorded at a pitch of 100 ° while the probe electrode was scanned on the track. Recording information is 10V with the probe electrode + side and the substrate electrode-side.
A rectangular pulse voltage of 5 μsec was applied.

Observation of the recording surface using STM revealed that a protrusion having a height of several tens of mm was formed at the recording position. Thereafter, the probe electrode was returned to the recording start point, and the recording layer was scanned again. At this time, Z was set to be substantially constant in reading the record. As a result, a probe current of about 10 nA flowed in the recording bit, and recording could be reproduced.

Example 11 Using the recording medium obtained in Example 1, an experiment of recording and reproduction was performed.

The recording / reproducing apparatus shown in FIG. 4 was used, and a probe electrode obtained by electrolytically polishing tungsten was used. The distance (Z) between the probe electrode and the surface of the recording layer is finely controlled by a piezoelectric element so that the current is kept constant. Further, the fine movement control mechanism is 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 can directly perform recording and reproduction. The recording medium is placed on a high-precision XY stage and can be moved to any position. The above recording medium
Placed on XY stage. Next, a voltage of 1 V was applied between the probe electrode and the recording medium, and the distance (Z) between the probe electrode and the recording layer surface was adjusted while monitoring the current. In this case, setting the probe current I _P for controlling the distance Z between the probe electrode and the recording layer surface so that _{^{10 -10 A ≧ I P ≧ 10}} -11 A. Initially, the probe electrode was set to match a reference marker provided in advance. A certain distance from the reference marker was moved along the step (track) of the track groove, and information was recorded at a pitch of 100 ° by scanning the recording surface in a direction perpendicular to the track groove direction. When a plurality of recording bits were formed, the probe electrode was returned to the original track position. Further, the probe electrode was moved along the 200 ° track, and information was recorded in the same manner. This was repeated. For recording information, a rectangular pulse voltage of 4 V, 50 μsec was applied with the probe electrode on the + side and the substrate electrode on the − side.

Observation of the recording surface using STM revealed that a protrusion having a height of several tens of mm was formed at the recording position.

Tracks were also observed. Thereafter, initial settings were made so that the probe electrode was adjusted to a reference marker provided in advance, as in the case of recording. A distance equivalent to the distance moved during recording along the track from the reference marker was moved. Information was reproduced by scanning the recording surface perpendicularly to the track groove direction while gently applying Z-axis feedback. At least the distance for reading all the recording bits was moved, and the probe electrode was immediately returned to the track when the movement was completed. At this time, after detecting a track to move the probe electrode to the Z-axis to determine whether feedback can be applied, the probe was moved several nm further in the same direction.
That is, when a tracking error was intentionally caused, the current from the bottom of the track groove could be sufficiently detected. From this, it was found that the probe electrode can always know the absolute position from the recording surface with respect to the Z-axis space. Thereafter, the probe electrode was returned to the recording start point, and the recording layer was scanned again. At this time, Z was set to be substantially constant in reading the record. As a result, a probe current of about 10 nA flowed in the recording bit, and recording could be reproduced.

Example 12 Using the recording medium obtained in Example 1, an experiment of recording and reproduction was performed.

The recording / reproducing apparatus shown in FIG. 4 was used, and a probe electrode made of platinum was used. The distance (Z) between the probe electrode and the surface of the recording layer is finely controlled by a piezoelectric element so that the current is kept constant. Furthermore, the fine movement control mechanism keeps the distance (Z) constant, and the in-plane (X,
It is designed so that fine movement control can also be performed in the Y) direction.

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

Next, a voltage of 1 V was applied between the probe electrode and the recording medium, and the distance (Z) between the probe electrode and the recording layer surface was adjusted while monitoring the current. At this time, the probe current I _P for controlling the distance Z between the probe electrode and the recording layer surface
It was set so that 10 ^-10 A ≧ I _P ≧ 10 ^-11 A. Next, information was recorded at a pitch of 100 ° while scanning the probe electrode on the track. To record information, set the probe electrode to the + side,
A rectangular pulse voltage of 10 V and 5 μsec was applied with the substrate electrode on the negative side.

Observation of the recording surface using STM revealed that a protrusion having a height of several tens of mm was formed at the recording position. Thereafter, the probe electrode was returned to the recording start point, and the recording layer was scanned again. At this time, Z was set to be substantially constant in reading the record. As a result, a probe current of about 10 nA flowed in the recording bit, and recording could be reproduced.

Example 13 In this example, a recording medium of the type shown in FIG. 3 was manufactured. First, one layer of polyisobutyl methacrylate (PIBM) was deposited on a fused quartz substrate by a Langmuir-Arbjet method (LB method). The thickness of one layer was about 10 °.

The method for forming a PIBM monolayer is described below. PI
BM was dissolved in chloroform to adjust the concentration to 1 g /.
This solution was developed on an aqueous phase composed of pure water at a water temperature of 20 ° C. to form a monomolecular film on the water surface. Increase surface pressure to 12mN / m,
The washed fused quartz substrate previously immersed in the aqueous phase was pulled up at a speed of 5 mm / min to form a PIBM monomolecular film.

An EB exposure apparatus (ELIONICS ELS-330)
According to 0), writing was performed at an acceleration voltage of 30 kV and a dose of 10 μC / cm ² . Development was performed with isopropyl alcohol / water (85/15). Subsequently, a film having a thickness of 1500 Å was formed by a vacuum deposition method at a deposition rate of 25 Å / sec. Then, an adhesive (KONISHI BOND HIGH TEMP H) is attached to the glass substrate (Corning # 7059).
A small amount of T-10) was applied and adhered to the Au surface of the substrate on which Au was deposited. The contact pressure was maintained at about 0.5 kg / cm ^2, and the mixture was left for 2 days while heating to 120 ° C. When the two substrates were peeled off, an electrode substrate having patterned tracks was obtained while maintaining the surface states of the fused quartz substrate and the patterned PIBM monomolecular film. The track groove depth was about 8 °.

Next, PI-DDE / P is formed as a recording layer 103 on the electrode substrate.
A Langmuir-Blodgett film of AA was formed. less than
The method of forming the PI-DDE / PAA LB recording layer will be described.

The monomolecular film of PI-DDE-PPA was formed on the electrode substrate with the track by two layers of PA by the film forming method described in Example 2.
Accumulate AD-DDE / PAA monolayer. By heating this thin film to 150 ° C. to form the recording layer 103, a recording medium in a recording / reproducing apparatus capable of reading a current value by bringing a probe close was obtained. Using this recording medium, an experiment of recording / reproduction / erasing was performed.

A platinum electrode was used as the probe electrode. This probe electrode is for controlling the distance (Z) from the surface of the recording layer, and the distance (Z) is finely controlled by a piezoelectric element so as to keep the current constant. Further, the fine movement control mechanism is 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 can directly perform recording / reproduction / erasing. The recording medium is placed on a high-precision XY stage,
It can be moved to any position. The recording medium described above was placed on an XY stage. Next, a voltage of 1.5 V was applied between the probe electrode and the substrate electrode of the recording medium, and while monitoring the current, the distance (Z) between the probe electrode and the recording layer surface was adjusted. In this case, the probe current I _P of 10 ^-10 A ≧ I _P ≧ 10 for controlling the distance Z between the probe electrode and the recording layer surface
^-11 A. Next, information was recorded at a pitch of 100 ° while scanning the probe electrode on the track. Information records a probe electrode (+) side, the substrate electrode - electrical memory materials in the side (polyimide thin film recording layer) is a low-resistance state (ON state) above the threshold voltage V _th shown in FIG. 6 which changes A rectangular pulse voltage was applied. Thereafter, the probe electrode was returned to the recording start point, and the recording layer was scanned again. At this time, adjustment was made so that Z was constant when reading the record. As a result, 10
It was shown that a probe current of about nA flowed and was in the ON state. The probe voltage is turned on for the electric memory material.
Threshold voltage _Vth OFF or more that changes from the off state to the off state
As a result of setting the voltage to 0 V and tracing the recording position again, it was confirmed that all the recordings were erased and the state transited to the OFF state.
The probe electrode was returned to the above-mentioned recording start point again, and re-recording was performed simultaneously with the above-mentioned recording method. The probe electrode was returned to the re-recording start point, and the recording layer was scanned to read out the recording. In the recording bit, it was confirmed that a current of about 10 nA flowed in the same manner as described above and was in the ON state.

Similar results were obtained when using a probe made of platinum and a tungsten wire electrolytically polished.

[Effects of the Invention] As described above, according to the recording medium of the present invention and the recording / reproducing apparatus using the same, 1) a tracking error such that the probe stops on the bottom of the track groove during recording / reproducing. Recovery can be easily performed even if the error occurs.

2) If it is located above the track groove at the time of access, it is possible to avoid contact with the track groove wall during scanning.

3) Patterned LB when forming track grooves
Although a film is used, the LB film can form a film having a smooth surface at several angstroms, and therefore, there is no projection that is illusion of a recording bit even inside the track groove.

[Brief description of the drawings]

FIG. 1 and FIG. 3 are sectional views showing the configuration of the recording medium of the present invention. FIG. 2 is a sectional view showing the structure of a conventional recording medium. FIG. 4 shows a configuration of a recording / reproducing apparatus using the recording medium of the present invention. FIG. 5 shows a process for producing a recording medium according to the present invention. FIG. 6 shows a rectangular pulse voltage waveform applied in recording information. FIG. 7 is a characteristic diagram showing electrical characteristics of the recording medium. 101 substrate (for forming electrodes) 102 metal electrode layer and recording layer 102 'metal electrode layer 103 recording layer 104 electrode surface corresponding to recording position 105 track 106 groove 107 … Smooth substrate 108 LB film 201 XY stage 202 Probe electrode 203 Probe electrode support 204 Linear actuator (Z axis) 205,206 Linear actuator (X, Y axis) 207 Pulse voltage circuit 301… Amplifier 302… Logarithmic compressor 303… Low-pass filter 304… Error amplifier 305… Driver 306… Drive circuit 307… High-pass filter

Claims (13)

(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, formed with a difference in height of irregularities of 1 nm or less and a concave surface with respect to the smooth surface adjacent to the smooth surface. An electrode layer having a track groove, and a recording layer formed on a smooth surface of the electrode layer, the characteristics of which transition between two or more states having different electrical conductivity by applying a voltage, A recording medium, wherein the track groove has a depth of 20 °. 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 the range of 4 ° to 20 °. 5. A method for manufacturing a recording medium having tracks on which information is recorded or reproduced by applying a voltage from a probe electrode, wherein a base material having a smooth surface with a height difference of 1 nm or less is prepared. Performing a step of forming an organic thin film having a thickness of 20 ° or less on a smooth surface of the base material, and patterning the organic thin film to leave a convex portion having a shape corresponding to the track, thereby forming the organic thin film. Exposing a smooth surface of the material, forming an electrode layer on the smooth surface and the projections of the base material, and bonding a substrate to a surface of the electrode layer opposite to a surface in contact with the base material. The step and, by peeling the electrode layer from the base material, the step of transferring the electrode layer to the substrate, and on the surface that was in contact with the smooth surface and the convex portion of the base material of the electrode layer transferred to the substrate, By applying voltage, the conductivity of each other The method of manufacturing a recording medium whose characteristics between two or more states characterized by comprising the step of forming a recording layer that changes made. 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 4 ° to 20 °. 9. The recording medium according to claim 1, wherein the surface of the recording layer of the recording medium is relatively scanned by a probe electrode disposed close to the surface, and the electrode layer is scanned. By applying a bias voltage between the probe electrode and the probe electrode, identifying the track of the recording medium by detecting the tunnel current flowing through the probe electrode, by applying a pulse voltage between the electrode layer and the probe electrode A recording method characterized by recording information. 10. The recording medium according to claim 1, wherein the surface of the recording layer of the recording medium is relatively scanned by a probe electrode arranged close to the surface, and the electrode layer is scanned. By applying a bias voltage between the probe electrode and the probe electrode, identifying the track of the recording medium by detecting the tunnel current flowing through the probe electrode, by applying a pulse voltage between the electrode layer and the probe electrode While recording information, while relatively scanning the surface of the recording layer on which the information is recorded by a probe electrode disposed close to the surface,
A recording / reproducing method, wherein information is reproduced by applying a bias voltage between the electrode layer and the probe electrode and detecting a tunnel current flowing through the probe electrode. 11. A recording medium according to claim 1, a probe electrode disposed close to a surface of a recording layer of the recording medium, and scanning the probe electrode relative to the recording medium. Scanning means for applying, a bias voltage applied between an electrode layer of the recording medium and a probe electrode, an identification circuit for identifying a track of the recording medium by detecting a tunnel current flowing through the probe electrode, and the recording medium A recording circuit for recording information by applying a pulse voltage between the electrode layer and the probe electrode. 12. The recording medium according to claim 1, a probe electrode disposed close to a surface of a recording layer of the recording medium, and scanning the probe electrode relative to the recording medium. A reproducing unit for reproducing information recorded on the recording layer of the recording medium by applying a bias voltage between the electrode layer and the probe electrode of the recording medium and detecting a tunnel current flowing through the probe electrode. A playback device comprising a circuit. 13. The recording medium according to claim 1, a probe electrode disposed close to a surface of a recording layer of the recording medium, and scanning the probe electrode relative to the recording medium. Scanning means for applying, a bias voltage applied between an electrode layer of the recording medium and a probe electrode, an identification circuit for identifying a track of the recording medium by detecting a tunnel current flowing through the probe electrode, and the recording medium A recording circuit for recording information by applying a pulse voltage between the electrode layer and the probe electrode, and a bias voltage applied between the electrode layer of the recording medium and the probe electrode, and a tunnel flowing through the probe electrode. A reproducing circuit for reproducing information recorded on the recording layer of the recording medium by detecting a current.