JPH04117642A - Recording medium, its manufacture recorder and reproducing device recorder, and reproducing device using relevant medium - Google Patents

Abstract

PURPOSE:To simplify a recording and reproduction, and to improve reproducibility by providing a convex track where a face operating a recording due to an electric memory effect, and the face of the side wall always make an obtuse angle, on a substrate. CONSTITUTION:A recording and reproducing device which detects currents flowing to elements by a probe electrode, is equipped with a convex physical track 2 and a recording layer 1 whose face has the electric memory effect. Then, the face which operates the recording due to the electric memory effect, and the face of the side wall of the track 2 make the obtuse angle. Thus, the edge part of the boundary of both the track 2 and the recording face can be easily detected, and the tracking which has high accuracy can be realized. Thus, the recording, reproduction, and erasing can be facilitated and the reproducibility of information can be improved.

Description

[Detailed description of the invention] [A field of application] The present invention is directed to a scanning tunnel! This paper relates to ultra-high density memory using the i-mirror principle.

[Problem B to be solved by conventional technology and invention] In recent years,
Memory devices are used in computers and related equipment,
It forms the core of the electronics industry, producing video discs, digital audio discs, etc., and its development is actively progressing. The performance required of memory devices is generally (1) high density and large storage capacity, (2) fast response speed for recording and playback, (3) low error rate, and (4) low power consumption. 5) High productivity and low price.

Until now, magnetic memory was made from magnetic materials or semiconductors,
Semiconductor memories have been the mainstream, but with advances in laser technology in recent years, optical memory devices have appeared that use inexpensive, high-density recording media that use organic thin films such as organic dyes and photopolymers.

On the other hand, recently, a scanning tunneling microscope (hereinafter abbreviated as STM) that can directly observe the electronic structure of surface atoms of a conductor has been developed [G. Binnig et al.
a Physica Acta) J 55,726
(1982), )], it has become possible to measure real space images with high resolution regardless of whether they are single crystal or amorphous, and it also has the advantage of being able to observe with low power without damaging the medium due to current. Moreover, since it can be operated even in the atmosphere, it is expected to have a wide range of applications.

STM utilizes the fact that a tunnel current flows when a voltage is applied between a metal probe (probe electrode) and a conductive substance and the probe is brought close to a distance of about 1 nm. This current is very sensitive to changes in the distance between the two, and by scanning the probe while keeping the tunneling current constant, it is possible to draw the surface structure in real space (at the same time, it is possible to draw various information about the total electron cloud of surface atoms). The in-plane resolution is about 0.1 nm. Therefore, applying the STM principle is sufficient for high-density recording and reproduction on the atomic order (0, several nm). The recording and reproducing method at this time is to perform appropriate recording using high-energy electromagnetic waves such as particle beams (electron beams, ion beams) or X-rays, and energy beams such as visible and ultraviolet light. A method of recording by changing the surface state of the layer and reproducing it with STM, and a thin film layer of a material that has a memory effect on voltage/current switching characteristics as a recording layer, such as a π-electron organic compound or chalcogenide. A method of recording and reproducing using STM has been proposed.

In the recording/reproducing method described above, in order to actually record/reproduce a large amount of information, position detection and correction control (tracking) of the probe electrode in the x-y force direction (direction in the plane of the recording medium) is required. Become. This tracking method is
A method has already been proposed that uses the atomic arrangement of the recording medium substrate to perform high-density and high-precision detection, but since the atomic arrangement must be detected with extremely high precision, it is difficult to say that it is easy to handle. Ta.

Therefore, in order to perform tracking easily, a guide groove (track) is formed by providing unevenness on the substrate of the recording medium in advance, and a probe electrode follows the concave or convex portion of the track. A method is proposed.

In this method, when detecting a track using a probe electrode, the current flowing between the probe electrode and the recording medium is constantly measured, and this current value is adjusted to be constant according to changes in the shape of the recording medium surface. By providing feedback to the element controlling the height of the probe electrode,
control the distance between the probe electrode and the medium, or
The track position is recorded by stopping this feedback, converting the value of the current flowing between the probe electrode and the recording medium, and measuring the distance between the probe electrode and the recording medium. On the other hand, the tip of the probe electrode has a certain finite radius of curvature. Therefore, if the shape change of the track portion on the surface of the recording medium is steep, the detection of the edge portion, which is the boundary between the track and the recording surface, will occur.
There is a risk of the track and probe electrode coming into contact.

However, in this conventional method, there was no consideration given to the angle of the side wall of the track with respect to the recording surface, which made it difficult to detect the edge of the boundary between the track and the recording surface during tracking using a probe electrode. Not only is it difficult to achieve highly accurate tracking, but there is also the problem that the probe electrode and the track may be damaged due to contact between the probe electrode and the side wall of the track.

In other words, an object of the present invention is to easily reproduce the recording and reproducing of a large amount of information in an electrical high-density recording and reproducing method using probe electrodes, in view of the problems of the prior art described above. The purpose of the present invention is to propose a recording medium and a method for manufacturing the same, which can be executed easily and efficiently, and a recording/reproducing apparatus, a recording apparatus, and a reproducing apparatus using such a recording medium.

[Means and effects for solving the problem] The present invention is characterized by a recording medium having a convex surface on the substrate in which the surface on which recording is performed by the electric memory effect and the surface of the side wall of the track are always at an obtuse angle. It consists in having a shaped track. Furthermore, there are features corresponding to the above-mentioned tracks in a method of manufacturing a recording medium including such a track, and in a recording/reproducing apparatus, a recording apparatus, and a reproducing apparatus each having such a recording medium.

As an example of the recording medium of the present invention, a cross-sectional view thereof is shown in FIG. Since it is used for is limited.

Methods for forming the convex steps that will become the tracks 2 on the substrate 4 include etching and lift-off of metals, inorganic materials, organic materials, etc. using conventional lithography technology using resist, or using the resist itself as the step. It is also possible to do so. It is also conceivable to form the step directly on the substrate by processing the substrate by irradiating it with high-energy radiation such as an electron beam or ion beam, or to form it by anisotropic etching of the Si substrate. Also,
A method of depositing a substance on a substrate by beam irradiation is also possible, and this method involves the formation of contaminants that adhere to the substrate when irradiated with an electron beam.

When forming a step as described above, it is necessary that the surface on which recording is performed by the electric memory effect and the surface of the side wall of the track always have an obtuse angle.For this purpose, when using lithography technology, it is necessary to use side etching for etching. When using the resist itself as a step, it is preferable to use a positive type. In addition, track formation using the adhesion of contamination caused by electron beam irradiation is possible because the intensity distribution of the electron beam is Gaussian, so the contamination also accumulates in the shape of a Gaussian distribution, so it is possible to record by the electric memory effect. This is the preferred method, as the plane of the track and the plane of the side wall of the track always form an obtuse angle.

In this way, it is necessary to form a conductive layer that will become the substrate electrode 3 on the substrate on which the tracks 2 are formed.

However, if the substrate 4 and the steps forming the tracks 2 are made of conductive material, it is not necessary to form this conductive layer. As a method for forming the conductive layer, it is possible to form a thin film evenly and uniformly on the substrate 4 on which tracks have been formed, such as by the very simple known sputtering method, but the method is not limited to this method. Any means that can form a conductive layer is possible.

As the material of the organic compound insulating layer used as the recording layer 1 in the present invention, any organic material may be used as long as it exhibits insulation properties.

Regarding the formation of an organic compound insulating layer, specifically, it is possible to apply vapor deposition methods, cluster ion beam methods, etc., but the LB method is extremely superior among known conventional techniques due to its controllability, ease, and reproducibility. suitable.

According to this LB method, it is possible to easily form a monomolecular film of an organic compound having a hydrophobic site and a lignophilic site in one molecule or a cumulative film thereof on a substrate, and to have a thickness on the order of a molecule. Moreover, it is possible to stably supply a uniform and homogeneous ultra-thin organic film over a large area.

The LB method is a molecule with a structure that has a hydrophilic site and a hydrophobic site, and when the balance between the two (balance of amphiphilicity) is maintained appropriately, the molecule has a lignophilic group on the water surface. This is a method of creating a monomolecular film or a cumulative film thereof by utilizing the fact that the monomolecular layer forms downward.

Examples of the group constituting the hydrophobic moiety include various hydrophobic groups such as generally widely known saturated and unsaturated hydrocarbon groups, fused polycyclic aromatic groups, and chain polycyclic phenyl groups. These each constitute a hydrophobic site singly or in combination. On the other hand, the most typical constituent elements of the wood-loving site are carboxyl groups, ester groups, acid amide groups, imide groups, hydroxyl groups, and amino groups (1, 2, tertiary, and quaternary), etc. Examples include wood-loving groups such as . These also constitute the tree-like part of the above molecule either singly or in combination.

Organic molecules that have both hydrophobic and hydrophilic groups in a well-balanced manner and have insulating properties can form a monomolecular film on the water surface, making them extremely suitable materials for the present invention. becomes.

The material of the substrate electrode 3 used in the present invention may be any material as long as it has high conductivity, such as Au.

There are many materials, including metals such as Pt, Ag, Pd, AJL, In, Sn, Pb, and W, and alloys thereof, as well as conductive oxides such as graphite, silicide, and even ITO. Application of these to the present invention is conceivable. Conventionally known thin film techniques are sufficient for forming electrodes using such materials. However, when forming the recording layer on the surface of the substrate electrode, it is preferable to use a conductive material that does not form an insulating oxide, such as an oxide conductor such as a noble metal or ITO. It is also preferable that the surface is smooth.

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

Since most organic materials generally exhibit insulating or semi-insulating properties, the present invention can be applied to a wide variety of organic materials having a group having a π-electron level.

Examples of structures of dyes having a π-electron system suitable for the present invention include phthalocyanine, dyes having a porphyrin skeleton such as tetraphenylporphyrin, azulene dyes having squarylium groups and croconic methine groups as bonding chains, quinoline, benzothiazole, Cyanine-based similar dyes in which two nitrogen-containing heterocycles are bonded by a squarylium group and a croconic methine group such as benzoxazole, or cyanine dyes, fused polycyclic aromatics such as anthracene and birene, and aromatic ring and heterocyclic compounds are polymerized chain compounds and diacetylene group polymers, as well as conductors of tetracyanoquinodimethane or tetrathiafulvalene, their normal analogs, and their charge transfer complexes, and furthermore ferrocene, trisbipyridine ruthenium complexes, etc. Examples include metal complex compounds.

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

Regarding the formation of the organic recording layer, it is also possible to specifically apply vapor deposition methods, cluster ion beam methods, etc., but the above-mentioned LB method is the most suitable among known conventional techniques due to its controllability, ease, and reproducibility. suitable.

Examples of the groups constituting the hydrophobic moiety include the widely known saturated and unsaturated hydrocarbon groups, fused polycyclic aromatic groups, and chain polycyclic phenyl groups. Examples include hydrophobic groups. These each constitute a hydrophobic site singly or in combination. On the other hand, the most typical constituent elements of the wood-loving site are carboxyl groups, ester groups,
Examples include acid amide groups, imide groups, hydroxyl groups, and wood-loving groups such as amino groups (1, 2, 3, and 4). These also constitute the tree-like part of the above molecule either singly or in combination.

Organic molecules that have a well-balanced combination of these hydrophobic groups and hydrophilic groups and a π-electron system with an appropriate size can form a monomolecular film on the water surface, and this is the It is an extremely suitable material for the invention.

Specific examples include the following molecules.

Organic materials in the margin below> [I] Croconic medium dye Here, R3 corresponds to the group with the σ electron level mentioned above, and was introduced to facilitate the formation of a monomolecular film on the water surface. A long-chain argyl group, the number of carbon atoms n is 5≦n≦
30 is preferred.

[■] Squarylium dye A compound in which the croconic methine group of the compound listed in [I] is replaced with a squarylium group having the following structure.

[+11] Porphy Phosphorous pigment compound air HI -CH2NIIC,l+.

M = H, Cu, Ni, Al2-CI! Rare earth gold ash ion and R=0CR(COOH)CnH,...5≦n≦25
M = if, Cu, Ni, Zn,
Al2-CR and rare earth metal ion R = CI, H, n, 550525M =
fiz, Cu, Ni, Zn, Al2
<I! and rare earth metal ion R are introduced to facilitate the formation of a monomolecular film, and are not limited to the substituents listed here. Also, R1
-R4,R corresponds to the group having the above-mentioned σ electron level.

[■l Condensed polycyclic aromatic compound■ OOH [V cocyacetylene compound 0113→C112 catties (:= c-c= C→CIt
2)7 XO≦n, l≦20 〉10〉10
11,-CONH, etc. can also be used.

[VI] Other quinquichenyl <organic polymeric materials> [I] Addition polymer polyacrylic acid polyacrylic acid ester acrylic acid copolymer 4] Acrylic acid ester copolymer [TI] Condensation polymer polycarbonate ■ -F-OCO-CH-C1+, )- [+11] Ring-opening polymer l) Polyethylene oxide-f-O-CI-CHd- Here, R1 is a long-chain alkyl group introduced to facilitate the formation of a monomolecular film on the water surface; The prime number n is 5≦n
≦30 is suitable.

Further, R4 is a short-chain alkyl group, and the number of carbon atoms n is 1≦n
≦4 is suitable. The degree of polymerization m is preferably 100≦m≦5000.

The compounds mentioned above as specific examples are only basic structures, and it goes without saying that various substituted products of these compounds are also suitable in the present invention.

It goes without saying that any organic material or organic polymer material other than those mentioned above is also suitable for the present invention as long as it is suitable for the LB method. For example, biomaterials (for example, bacteriorhodopsin and cytochrome C) and synthetic polypeptides (PBLG), which have been actively researched in recent years, can also be applied.

The electrical memory effect of compounds with these π electron levels has been observed in films with a thickness of several 1101 L or less;
Since a tunnel current flowing between the probe electrode and the substrate electrode is used during recording and reproduction, the distance between the probe electrode and the substrate electrode must be shortened so that the tunnel current flows between the probe electrode and the substrate electrode. The thickness of the added layer is 0. The thickness is several nm or more and 10 nm or less, preferably O0 is several nm or more and 3 nm or less.

Further, the material of the probe electrode 5 may be any material as long as it exhibits conductivity, such as Pt.

Examples include Pt-Ir, W, Au, and Ag. The tip of the probe electrode needs to be as sharp as possible to increase the resolution of recording, playback, and erasure. In the present invention, a probe electrode is produced by controlling the shape of the tip of a needle-shaped conductive material using an electropolishing method, but the method and shape of the probe electrode are not limited thereto.

Furthermore, the number of probe electrodes does not need to be limited to one; a plurality of probe electrodes may be used, such as one for position detection and one for recording/reproduction.

Next, a recording/reproducing apparatus using the recording medium of the present invention will be explained using the block diagram shown in FIG. In FIG. 1, reference numeral 5 denotes a probe electrode for applying a voltage to the recording medium, and recording and reproduction are performed by applying a voltage to the recording layer 1 from this probe electrode.

The target recording medium is placed on the XY stage 12. This XY stage 12 allows recording and recording on the recording medium.
The rough location for playback is set. IO is a probe current amplifier, and 9 is a servo circuit that controls the Z-direction fine movement control mechanism 7 using a piezoelectric element so that the height of the probe electrode from the recording medium is constant. Reference numeral 11 denotes a power source for applying a pulse voltage for recording and erasing between the probe electrode 5 and the substrate electrode 4. Note that when applying the pulse voltage, the probe current changes rapidly, so the servo circuit 9 uses HOL to keep the output current constant during that time.
It is controlled to turn on the D circuit.

8 is an XY scanning drive circuit for controlling the movement of the probe electrode 5 in the XY force direction using the XY direction fine movement control mechanism 6. The coarse movement mechanism 13 and the coarse movement drive circuit 14 coarsely control the distance between the probe electrode 5 and the recording medium so that a probe current of about 10-'A can be obtained in advance.
It is used to increase the relative displacement between the probe electrode and the substrate in the XY direction (outside the range of the fine movement control mechanism).

All of these devices are centrally controlled by a microcomputer 15. Further, 16 represents a display device.

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

Two-direction fine movement control range: 0.1 layer m to 1 μm Z direction coarse movement control range: 10 layers m to I Omm XY direction scanning range: 0. 1 nm ~ 1 um XY direction coarse movement control range: 10 layers m ~ 10 mm Measurement, control tolerance: <
O, lnm (during fine movement control) Measurement and control tolerance: <lnm (during coarse movement control) The present invention will be described below according to examples.

[Example] Example 1 After cleaning an optically polished glass substrate (substrate 4) using a neutral detergent and Triclean, the substrate was irradiated with an electron beam using an electron drawing device to remove contaminants.
Track 2 was formed. The electron beam drawing conditions at this time were an acceleration voltage of 30 kV and an electron beam current of 8 x 10
-”A, spot diameter 0.1μm, sweep speed 10-'mm
/SeC, and 1.0 mm x 0 as shown in Figure 2.
．． 5mm area with 2.0μm pitch, length 1mm, width 0
．． Tracks of 1 μm were formed.

At this time, the height of the track was 0.01 μm, and the cross section in the width direction was approximately in the shape of a Gaussian curve. Also, the degree of vacuum during drawing is 8X10-'T in the sample chamber.
orr, and the electron gun chamber was 5×1 CM'Torr.

Next, on the substrate, Au was deposited to a thickness of 1 nm by sputtering to form a substrate electrode 3, and then a polyimide LB film, which was to become a recording layer 1, was formed. The method for forming this LB film will be described below.

A mixed solution of dimethylacetamide and benzene in which polyamic acid (hereinafter abbreviated as PA) is dissolved at a repeating unit concentration of 1.0 mmoJ2I2/ρ is spread on pure water at 20°C, and after evaporating and removing the solvent from the water surface, Surface pressure 25
mN/m to form a monomolecular film on the water surface. next,
While maintaining this surface pressure constant, the substrate was gently immersed across the water surface at a speed of 5 mm/min, and then pulled up to accumulate two Y-shaped monomolecular films. Next, the substrate was heat-treated at 300° C. for 10 minutes to imidize the PA cumulative film to form a polyimide (hereinafter abbreviated as PI) thin film to form an organic compound insulating layer.

Recording/playback/recording/playback is performed on the recording medium created by the method described above using the recording/playback/recording/playback device shown in Figure 1.
We conducted an erasure experiment. However, as the probe electrode 5, a platinum/rhodium probe electrode prepared by an electric field polishing method was used. This probe electrode 5 can be used for directly recording, reproducing, and erasing. The distance (Z) between the probe electrode 5 and the recording layer 1 is controlled by applying an appropriate voltage from the servo circuit 9 to the Z-direction fine movement control mechanism 7, and furthermore, while maintaining this function, the probe electrode 5 is The XY direction fine movement control mechanism 6 is controlled by the XY scanning drive circuit 8 so that the movement can be controlled in the (X, Y) directions as well. Further, the recording medium is placed on a high-precision XY stage 12 and can be moved to any position. Therefore, this movement control mechanism allows the probe electrode 5 to perform recording, reproduction, and erasing at any position on the recording medium.

A recording medium having a recording layer 1 in which PI27iF was accumulated as described above was set in a recording/reproducing apparatus. At this time, track 2
The recording/playback device was installed so that its length direction and the Y direction of the recording/reproducing device were almost parallel. Next, apply a voltage of -1.0 to the probe electrode 5 with respect to the substrate electrode 3 of the recording medium, and measure the distance (Z) between the probe electrode 5 and the substrate electrode 3 while monitoring the current flowing through the recording layer 1. adjusted. Thereafter, by controlling the Z-direction fine movement control mechanism 7 to change the distance between the probe electrode 5 and the surface of the recording layer 1, current characteristics as shown in FIG. 3 were obtained. Note that the distance 2 between the probe electrode 5 and the surface of the recording layer 1 can be adjusted by changing the probe current and the probe voltage, but in order to keep the distance Z constant at an appropriate value, the probe current must be changed. I, is 10-'A≧
engineering, ≧1O-12A, preferably 10-”A≧engineering, ≧10
It is necessary to adjust the probe voltage so that the voltage is 0.5V and the probe current is set to 10-'A (corresponding to region b in Figure 3). The distance between the probe electrode 5 and the surface of the recording layer 1 was controlled.Next, while keeping this distance 2 constant, the probe electrode 5 was scanned in the X direction, that is, in the direction across track 2, and track 2 was formed on the recording medium. After confirming that the probe electrode 5 is formed, move the probe electrode 5 to any two adjacent tracks 2.
(recording surface).

Next, while scanning the probe electrode 5 along the track 2, information was recorded at a pitch of 5 nm. Tracking is performed by keeping the output voltage of the servo circuit 9 constant (HOLD circuit O
(N), it can also be performed with the servo circuit 9 operating (HOLD circuit 0FF). At this time, track 2 is detected when the output voltage of the servo circuit 9 is kept constant (H
OLD circuit ON) is increased until the probe current is saturated, and the servo circuit 9 is kept operating (HOLD circuit 0F).
In the case of F), the change in the output voltage of the servo circuit is 3.
Track 2 was recognized by the increase in v. Recording of such information is performed using a pulse voltage (V, , = -15V) that is higher than the threshold voltage Vt, hos and has a waveform similar to that shown in Fig. 4(a).
was applied to write the ON state. Note that when applying the pulse voltage, the output voltage of the servo circuit 9 is kept constant. The written information is written after controlling the distance between the probe electrode 5 and the surface of the recording layer 1 under the same conditions as when writing.
While keeping the output of the servo circuit 9 constant, scan the probe electrode 5 and directly read the changes in probe current between the ON state area and the OFF state area, or leave the servo circuit 9 operating (HOLD). Circuit 0FF) By scanning the probe electrode 5, it is possible to read the change in the output voltage of the servo circuit 9 between the ON state region and the OFF state region. In this example, it was confirmed that the probe current in the ON state region changed by more than three orders of magnitude compared to before recording (or in the OFF state region).

Furthermore, after controlling the distance between the probe electrode 5 and the surface of the recording layer 1 under the same conditions as during writing, the output of the servo circuit 9 is held constant, and the probe voltage V th is set. 0 or more 8■
(FIG. 4(b)), and as a result of scanning the probe electrode 5 again and tracing the recorded position, it was confirmed that all recorded states were erased and the state transitioned to the OFF state. In the above playback experiment, the pit error rate was 3X10
-6.

Furthermore, when the cross section of this recording medium in the direction across the track 2 was observed with an electron microscope, the height of the track 2 was 10 nm as shown in Fig. 3, and the cross section was a Gaussian curve. The surface on which recording is effected and the surface of the side wall of track 2 always have an obtuse angle, and especially the edge portion, which is the boundary between track 2 and the recording surface, has a very gentle curve.

Example 2 A substrate electrode 3 with a thickness of 30 nm was formed in the same manner as in Example 1 on a substrate 4 that had been cleaned in the same manner as in Example 1, and Cr was further deposited to a thickness of 30 nm by a normal vapor deposition method, and then a negative resist (
Hitachi Chemical RD-200ON-10) was applied, and after a bre-bake (80°C for 20 minutes), exposure to far ultraviolet rays and development using a special developer were performed to obtain lines and spaces of 0.5 μm and length of 2 mm. A resist pattern was formed. Next, the substrate 4 is subjected to a boss bake (120°C
After 20 minutes), Cr was etched by dipping it in a Cr etching solution for 30 seconds, and finally the resist was removed with acetone. On the substrate on which track 2 was formed as described above, a PI thin film was formed in the same manner as in Example 1 (6th
figure). Recording, reproducing, and erasing experiments were conducted on the thus prepared recording medium in the same manner as in Example 1. As a result, the pit error rate was 5×10 −′, and erasing was also possible.

Furthermore, when a cross section of this recording medium in the direction across the track 2 was observed using an electron microscope, it was found that the surface where recording is performed by the electric memory effect and the surface of the side wall of the track 2 always form an obtuse angle, as shown in FIG. In particular, the edge portion, which is the boundary between track 2 and the recording surface, had a very gentle curve.

Comparative Example 1 After hydrophobically treating the substrate 4 cleaned in the same manner as in Example 1 with hexamethyldisilazane, a negative resist (Hitachi Chemical RD-200ON-10) was applied, and a brebake (8
After 20 minutes at 0° C., exposure to deep ultraviolet rays and development using a special developer were performed for 60 seconds to form a resist pattern with a line and space of 0.5 μm and a length of 2 mm, which was designated as track 2. Next, after the substrate was post-baked (120°C for 20 minutes), a thin film of Au and PI was formed on the substrate 4 in the same manner as in Example 1 (Fig. 11).
. Example 1 for the recording medium created as described above
Recording, playback, and erasing experiments were conducted in the same manner as above. As a result, during tracking, it was difficult to confirm track 2, the pit error rate was significantly worse than in Example 1, and the probe electrode 5 used and the track where the recording/playback experiment was performed 2 was observed with an electron microscope, it was found that the tip of the probe electrode 5 was bent and the track 2 was damaged. When a cross section of this recording medium in the direction across track 2 was observed using an electron microscope, it was found that the surface on which recording is performed by the electric memory effect and the surface of the side wall of track 2 are almost perpendicular or at a slightly acute angle, as shown in Figure 11. there were.

Example 3 A positive resist (Tokyo Ohka TSMR-8800) was coated on a glass substrate 4 that had been cleaned in the same manner as in Example 1, and after blebake (90°C for 30 minutes), exposure to deep ultraviolet rays (
A resist pattern with a line and space of 0.6 μm and a length of 2 mm was formed by developing with Nikon NSR-1505G3A) and a special developer. Next, the substrate 4 was post-baked (120° C. for 20 minutes), and then a thin film of Au and PI was formed in the same manner as in Example 1 to form a recording medium (FIG. 7). Recording, reproducing, and erasing experiments were conducted in the same manner as in Example 1 on the recording medium prepared as described above. As a result, the pit error rate was 5.
X10-'', and erasing was also possible.

Furthermore, when a cross section of this recording medium in the direction across the track 2 was observed with an electron microscope, it was found that the surface where recording is performed by the electric memory effect and the surface of the side wall of the track 2 always form an obtuse angle, as shown in FIG. In particular, the edge portion, which is the boundary between track 2 and the recording surface, had a very gentle curve.

Example 4 A substrate electrode 3 with a thickness of 30 nm was formed in the same manner as in Example 1 on a glass substrate 4 that had been cleaned in the same manner as in Example 1, and a negative resist (Hitachi Chemical RD-200ON-10) was further applied.
After B-L and B-1 (80'C, 20 minutes), exposure to deep ultraviolet rays and development using a special developer were performed to form a resist pattern with a line and space of 0.5 μm and a length of 2 mm. Next, the related board is boss baked (
120°C for 20 minutes), then 3% Au was deposited by vacuum evaporation method.
It was formed with a thickness of 0 nm. Next, the substrate 4 was subjected to ultrasonic cleaning while immersed in acetone, and the resist was peeled off. Finally, in the same manner as in Example 1, a recording layer 1 was formed to obtain a recording medium (FIG. 8). Recording, reproducing, and erasing experiments were conducted in the same manner as in Example 1 on the recording medium prepared as described above. As a result, the pit error rate was 5×10
-6, and erasing was also possible.

Furthermore, when a cross section of this recording medium in the direction across the track 2 was observed using an electron microscope, it was found that the surface on which recording is performed by the electric memory effect and the surface of the side wall of the track 2 always form an obtuse angle, as shown in FIG. In particular, the edge portion, which is the boundary between track 2 and the recording surface, had a very gentle curve.

Example 5 A substrate electrode 3 with a thickness of 30 nm was formed in the same manner as in Example 1 on a substrate 4 that had been cleaned in the same manner as in Example 1. Furthermore, a recording layer 1 was formed in the same manner as in Example 1, and then a recording layer was formed. Tracks 2 of Cr were formed on the layer 1 by etching in the same manner as in Example 2 to form a recording medium (FIG. 9). Recording, reproducing, and erasing experiments were conducted in the same manner as in Example 1 on the recording medium prepared as described above. As a result, the pit error rate was 5.
X10-', and erasing was also possible.

Furthermore, when a cross section of this recording medium in the direction across the track 2 was observed using an electron microscope, it was found that the surface where recording is performed by the electric memory effect and the surface of the side wall of the track 2 always form an obtuse angle, as shown in FIG. In particular, the edge portion, which is the boundary between track 2 and the recording surface, had a very gentle curve.

Example 6 A recording medium having tracks 2 formed by anisotropically etching a Si substrate was produced.

The method is shown below.

First, the oxide film on the surface of the SL substrate is etched using a known resist and an etching solution so that the lines and spaces are 0.
It was patterned with a thickness of 5 μm and a length of 2 mm. Thereafter, the Si portion of the substrate 4 was anisotropically etched for 3 minutes using a KOH solution to form tracks 2, and then the Si oxide film was removed.

On the substrate 4 on which the tracks 2 were formed as described above, thin films of Au and PI were formed in the same manner as in Example 1 (FIG. 10).

Recording, reproducing, and erasing experiments were conducted on the thus prepared recording medium in the same manner as in Example 1. the result,
The pit error rate was 5×10'', and erasing was possible.

Furthermore, when a cross section of this recording medium in the direction across track 2 was observed using an electron microscope, it was found that the surface where recording is performed by the electric memory effect and the surface of the side wall of track 2 were always at an obtuse angle, as shown in Figure 10. .

In the examples described above, track formation was carried out by a process using contamination and resist generated during electron beam irradiation, but it is not limited to this. (If steps can be physically formed, any For example, it is possible to form grooves directly on the substrate by irradiating high-energy radiation such as an ion beam.In addition, as for the shape of the track, we have described a linear one. However, the LB method is not limited to this, and may be in the form of a spiral, circular, etc.Also, the LB method has been used to form the organic compound insulating layer and the recording layer, but it is not possible to form an extremely thin and uniform layer. L if it is a film formation method that can create a film
It can be used not only for method B, but specifically for MBE and CV.
Film forming methods such as the D method can be mentioned. Furthermore, the present invention does not limit the substrate material or its shape in any way. Furthermore, although one probe electrode is used in this embodiment, two or more probe electrodes may be used, one for recording/reproduction and one for tracking.

[Effects of the Invention] As described above, according to the present invention, it is possible to simplify the manufacturing process of a completely new recording medium that is capable of recording at a much higher density than optical recording. Become.

■ Track detection is easy during recording, playback, and erasing, and there is no risk of damage to probe electrodes or tracks.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the configuration of a recording/reproducing apparatus used in the present invention. FIG. 2 is a diagram showing an example of a track pattern formed on the recording medium of the present invention. FIG. 3 shows the current characteristics of the recording medium of the present invention. FIG. 4(a) shows a pulse signal waveform applied when recording on the recording medium of the present invention. FIG. 4(b) shows a pulse signal waveform applied to the recording medium of the present invention when erasing data. 5 to 10 are cross-sectional views of the recording medium of the present invention. FIG. 11 is a diagram showing a cross section of a conventional recording medium. 1... Recording layer 2... Track 3... Substrate electrode 4... Substrate 5... Probe electrode 6... XY direction fine movement control mechanism... Two direction fine movement control mechanism 8... XY direction scanning drive circuit 9...Servo circuit 10...Probe current amplifier 11...Pulse power supply 12...XY stage 13
...Coarse movement mechanism 14...Coarse movement drive circuit 15...
・Microcomputer 16...Display device

Claims (14)

[Claims] (1) A recording medium used in a recording/reproducing device that detects a current flowing through an element using a probe electrode, the recording medium having a physically convex track and a recording layer having an electric memory effect on the surface of the recording medium. A recording medium characterized in that the surface on which recording is performed by the electric memory effect and the surface of the side wall of the track are always at an obtuse angle. (2) The method for manufacturing a recording medium according to claim (1), wherein the track is formed by contamination added to the irradiated surface when the electron beam is irradiated. (3) The method for manufacturing a recording medium according to claim (1), wherein the tracks are formed with a positive type resist. (4) The method for manufacturing a recording medium according to claim (1), wherein the tracks are formed by etching using a resist. (5) The method for manufacturing a recording medium according to claim (1), wherein the tracks are formed by lift-off using a resist. (6) The method for manufacturing a recording medium according to claim (1), wherein the tracks are formed by anisotropic etching of the Si substrate. (7) A recording/reproducing device comprising the recording medium according to claim (1). (8) A recording device comprising the recording medium according to claim (1). (9) A reproducing device comprising the recording medium according to claim (1). (10), the thickness of the recording layer is 0. The recording medium according to claim (1), characterized in that it is several nm or more and 10 nm or less,
The recording medium manufacturing method according to claims (2), (3), (4), (5), and (6), the recording and reproducing apparatus and recording apparatus according to claims (7), (8), and (9), playback device. (11), the thickness of the recording layer is 0. The recording medium according to claim (1), characterized in that the thickness is several nm or more and 3 nm or less, the method for manufacturing a recording medium according to claims (2), (3), (4), (5), or (6), A recording and reproducing device, a recording device, and a reproducing device according to claims (7), (8), and (9). (12) The recording medium according to claim (1), wherein the recording layer has a monomolecular film of an organic compound or a cumulative film formed by accumulating the monomolecular film; claims (2) and (3) ,(4
), (5), and (6), the recording medium manufacturing method described in claim (
7), (8), and (9) recording and reproducing devices and recording devices;
playback device. (13) The recording medium, recording medium manufacturing method, recording and reproducing apparatus, recording apparatus, and reproducing apparatus according to claim (12), wherein the monomolecular film or the cumulative film is a film formed by the LB method. . (14) The recording medium, recording medium manufacturing method, and recording/reproduction according to claim (12), wherein the organic compound has a group having a π electron level and a group having a σ electron level in the molecule. equipment, recording equipment, playback equipment.