JP2992909B2 - Manufacturing method of recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a high-density recording medium. More specifically, use in an information processing device to which a scanning tunneling microscope (STM) is applied.
The present invention relates to a method of manufacturing a recording medium capable of performing the following.

[0002]

2. Description of the Related Art In recent years, with the development of the information society, the development of large-capacity memories has been very actively performed. The performance required of the memory generally includes 1) high density and large recording capacity 2) fast response time for recording and reproduction 3) low power consumption 4) high productivity and low price.

On the other hand, recently, a scanning tunneling microscope (S
TM) was developed (G. Binning et al.
Phys. Rev .. Lett. 49, 57 (198
2)), high resolution measurement in real space can be performed irrespective of single crystal or amorphous.

[0004] Such STM utilizes the fact that a tunnel current flows when a voltage is applied between a metal probe (probe electrode) and a conductive substance to approach a distance of about 10 °. This current is very sensitive to changes in the distance between the two, and by scanning the probe so as to keep the tunnel current constant, it is possible to draw the surface structure in real space, and at the same time, various kinds of information on the total electron cloud of surface atoms Information can also be read. The resolution in the in-plane direction at this time is about 1 °.

Therefore, if the principle of STM is applied, it is possible to perform high-density recording / reproducing on the order of atoms (several Å). As a recording / reproducing method at this time, recording is performed by changing the surface state of an appropriate recording layer using a high energy electromagnetic wave such as a particle beam (electron beam, ion beam) or X-ray and an energy beam such as visible / ultraviolet light. The recording and reproduction are performed by using a material having a memory effect on the switching characteristics of voltage and current, for example, a thin film layer of a π-electron organic compound or chalcogenide as a recording layer.
A method using a TM has been proposed (Japanese Unexamined Patent Publication No.
161552, 3). In addition, there has been proposed a method and an apparatus for capturing molecules from a fluid on a substrate by applying a voltage pulse, selectively writing data bits, and reading and erasing the data bits (Japanese Patent Laid-Open No. 1-196751).
No.).

Incidentally, in order to actually perform recording and reproduction on a memory medium as an apparatus, it is necessary to perform so-called tracking positioning and tracking to a data string. As a method of manufacturing an electrode substrate having a track of this type of high-density memory, 1) forming a track on the electrode substrate by using lithography technology 2) applying an atomic arrangement of crystals 3) forming a conductor on a recording medium Embedding tracks 4) Proposing a concave or convex portion on a base material, depositing a metal layer on the base material, and then separating the metal and using the separated surface as an electrode surface. .

[0007]

When the electrode substrate shown in the above-mentioned conventional example is used, the recording density may be lowered and the manufacturing process may be complicated. Is required to provide a recording medium.

That is, the object of the present invention is to
Recording that can solve the problems in the prior art as described above
An object of the present invention is to provide a method for manufacturing a medium .

[0009] The structure of the present invention for achieving the above object is as follows. First, on a cleavage plane of a crystal substrate or on a molten glass substrate.
A process of forming a metal layer thereon and a convex track pattern
The surface of the transfer material on which is formed is opposed to the surface of the metal layer.
Remove the transfer material after placing it and applying pressure from above the transfer material.
Thereby, a concave track pattern is formed on the surface of the metal layer.
The transfer process and the concave track pattern is transferred
Forming a recording layer on the metal layer.
Manufacturing method, secondly, on a cleavage plane of a crystal substrate or molten glass
Forming a metal layer on a metal substrate;
A step of bonding a plate, and a step of bonding the gold bonded to the substrate.
Removing the crystal substrate from the metal layer,
The surface of the transfer material on which the turn is formed is formed by the crystal group of the metal layer.
Place the plate facing the surface where the board has been peeled off, and apply pressure from above the transfer material.
After removing the transfer material, the metal layer surface
Transferring a concave track pattern to the
Form a recording layer on the metal layer to which the rack pattern has been transferred.
Thirdly, a method for manufacturing a recording medium comprising:
The recording layer is formed by the Langmuir-Blodgett method.
3. Production of the recording medium according to any one of the first and second aspects
Method, and the point.

The details of the present invention will be described below.

FIG. 1 is a cross-sectional view showing the steps of manufacturing an electrode substrate having tracks according to the present invention. 101 is a substrate, 102 is an electrode layer, 103 is a transfer material,
104 is a track pattern, and 104 'is a transferred track pattern. In FIG. 1, first, an electrode substrate having an electrode layer 102 on a substrate 101 is prepared. This electrode substrate may be one in which an electrode layer is formed directly on the substrate,
It is also possible to use a peeled surface obtained by peeling the electrode layer from the base material.

In order to perform high-speed, high-density recording utilizing the characteristics of the STM, an electrode substrate capable of realizing a high S / N ratio and high-speed recording / reproduction is required. Therefore, it is preferable that the surface of the substrate 101 is smooth. For example, 1) a cleavage plane of a crystal: mica, MgO, TiC, Si, graphite, etc. 2) a molten glass surface: float glass, Corning #
7059, fused quartz and the like.

The surfaces of these various materials can be observed using an atomic force microscope (AFM). Such A
FM can measure the surface shape of a sample with atomic-order resolution regardless of the conductivity or insulation of the sample. The present inventors observed the surface shape of each of the above-mentioned materials using an AFM.
It was found that it had a smoothness of not more than nm and was suitable as a substrate used in the present invention.

Here, it is preferable that the electrode layer 102 has high conductivity. For example, Au, Ag, Pt, P
Metals such as d and alloys such as Au-Pd and Pt-Pd, as well as their laminated films. As a method of forming an electrode using such a material, a conventionally known method of forming a thin film is sufficient.

When a peeled substrate is used as an electrode substrate, the electrode substrate can be formed by forming an electrode layer on the base material using the above substrate as a base material, and copying the electrode layer onto a separately prepared peeled substrate. In this case, the release substrate only needs to have smoothness, and may be the same or different from the base material. As for the peeling method, eutectic bonding, electroforming and the like can be used in addition to peeling using an adhesive. As such an adhesive, a non-solvent type that does not have volume shrinkage is preferable.
Epoxy resins, polyimide resins and the like can be mentioned.

On the other hand, a transfer material having a track pattern only needs to be able to form a desired track pattern, and there is no limitation in the present invention. Also, a conventionally known lithography technique can be used as a method of forming a track pattern, and there is no limitation on its shape.

[0017]

Embodiments of the present invention will be described below.
Examples 1 to 4 correspond to the manufacturing process of the recording medium of the present invention.
Among them, an embodiment relating to production of an electrode substrate in particular.

(Example 1) As shown in FIG. 2, a Corning # 7059 glass substrate is washed to form a substrate 101 (FIG. 2 (a)). Subsequently, an Au film is formed on the substrate 101 by a vacuum evaporation method to form an electrode layer 102 (FIG. 2B). The electrode layer 102 has a substrate temperature of 400 ° C.
Vapor deposition rate 10Å / sec, ultimate pressure 2 × 10 ^-6 Torr
The film was formed under the conditions of r and a film pressure of 2000 °.

[0019] On the other hand, SiO ₂ is 1μ as a transfer material 103
An m-formed Si substrate was used (FIG. 2C). After washing the transfer material, an EB resist (trade name: OEB)
R-1000 (manufactured by Tokyo Ohka), exposed and developed to form a desired track pattern 104.
(D)) EB lithography conditions are acceleration voltage of 20 kV and dose amount of 5
It was 0 μC / cm ² .

Subsequently, using the resist pattern as a mask, SiO ₂ was etched. The etching depth was 1000 °, the pressure was 5 Pa using CF ₄ as an etching gas, and the discharge power was 150 W. Thereafter, the resist was peeled off using methyl ethyl ketone, and a convex track pattern 104 was formed.

Next, the transfer material 103 is disposed on the electrode substrate so as to oppose it (FIG. 2E). After applying a pressure of 5 kg / cm ² from above the transfer material, the transfer material is removed (FIG. 2F). )).

When the surface of the electrode substrate prepared by the above method was observed by STM, a concave track pattern 104 'was formed at 10 μm square, and the tracks could be clearly discriminated.

(Example 2) First, mica is cleaved in the air to form a substrate 101. Subsequently, Au was deposited under the same conditions as in Example 1 to form an electrode layer 102. Example 1
The transfer of the track pattern was performed in the same manner as in Example 1 using the transfer material 103 formed in the step (1).

When the surface of the electrode substrate prepared by the above method was observed by STM, a concave track pattern was formed at 10 μm square, and the tracks could be clearly identified. Further, it was found that the transfer material could be used repeatedly.

Embodiment 3 As shown in FIG. 3, mica is cleaved in the air, and an electrode layer 102 is formed on the mica 101.
Au was epitaxially grown. The deposition conditions at this time are the same as in the first embodiment. Subsequently, the adhesive 105
After applying (trade name: High Super 5 manufactured by Cemedine), a release substrate 106 is attached on the adhesive 105.
Bonding was performed at 3 kg / cm ² , room temperature, and a curing time of 24 hours. Subsequently, the substrate 101 was peeled from the electrode layer 102 to obtain an electrode substrate including the substrate 105, the electrode layer 102, and the adhesive 105.

Next, using the transfer material formed in Example 1, the track pattern was transferred in the same manner as in Example 1.

When the surface of the electrode substrate prepared by the above-described method was observed by STM, a concave track pattern was formed at 10 μm square, and the tracks could be clearly identified. Further, it was found that the transfer material could be used repeatedly.

(Example 4) On a cleaned fused quartz substrate,
Au was deposited in the same manner as in Example 1. Next, Example 1
The transfer material formed in step 2 was placed so as to face the electrode substrate, and a pressure of 5 kg / cm ² was applied from above the transfer material. At this time, the electrode substrate temperature was set to 600 ° C., and the pressurizing and heating time was set to 1 minute. Thereafter, the substrate temperature was returned to room temperature, and the transfer material was removed.

When the surface of the electrode substrate prepared by the above method was observed by STM, a concave track pattern was formed at 10 μm square, and the tracks could be clearly identified. Further, it was found that the transfer material could be used repeatedly.

Example 5 An electrode substrate was formed in the same manner as in Example 1 (FIGS. 4A to 4F). Next, FIG.
As shown in (g), a four-layer polyimide Langmuir-Blodgett film (LB film) was formed on the electrode substrate to form a recording layer 107. Hereinafter, formation of the polyimide LB film by the Langmuir-Blodgett method will be described.

First, polyamic acid was dissolved in N, N'-dimethylacetamide (concentration in terms of monomer of 1 × 10
^-3 M) and a separately prepared 1 × 10 ⁻³ M solution of N, N′-dimethyloctadecylamine in the same solvent, in a ratio of 1: 2 (V
/ V) to prepare a polyamic acid octadecylamine salt solution.

This solution was spread on an aqueous phase composed of pure water at a water temperature of 20 ° C., and a monomolecular film was formed on the water surface. After removing the solvent by evaporation, the surface pressure was increased to 25 mN / m. While keeping the surface pressure constant, the above electrode substrate was gently immersed in a direction crossing the water surface at a speed of 5 mm / min.
The film was gently pulled up at a rate of / min to form a two-layer Y-type monomolecular cumulative film. By repeating this operation, a four-layer monomolecular cumulative film of polyamic acid octadecylamine salt was formed. This substrate was heated and baked at 300 ° C. for 10 minutes under reduced pressure to imidize the octadecylamine polyamic acid salt, thereby obtaining a four-layer polyimide monomolecular film.

Next, when the surface shape of the recording medium was examined by the information processing apparatus shown in FIG. 5 using the recording medium prepared by the above method, the surface of the recording medium reflected the smooth surface of the electrode. The surface unevenness was 1 nm or less.

Next, an experiment of recording and reproducing information was performed using the apparatus shown in FIG.

As the probe electrode 202, a probe electrode made of platinum-rhodium was used. The probe electrode controls a distance Z from the surface of the recording layer 107, and the distance Z is finely controlled by a piezoelectric element so as to keep the current constant. Further, the linear actuator 204,
205 and 206 are designed so that fine movement control can be performed in the in-plane (X, Y) direction while keeping the distance Z constant. Further, the probe electrode can directly perform recording, reproduction, and erasing.

On the other hand, the recording medium is placed on the high-precision XY stage 201 and can be moved to any position. The above-described recording medium is placed on the XY stage, and a positive electrode is provided between the probe electrode and the electrode layer 102 of the recording medium.
While applying a voltage of 1.5 V and monitoring the current, the probe current I _p for controlling the distance Z between the probe electrode 202 and the surface of the recording layer 107 is increased to 10 ⁻¹⁰ A ≧ I _p ≧ 10
^-11 A was set.

Next, the probe electrode 202 is connected to the recording layer 107.
While scanning on the above, information was recorded at a pitch of 100 °.

The recording of such information is performed by the probe electrode 202.
When the recording layer (four polyimide LB films) having a memory property with respect to the voltage-current switching characteristics changes to the low resistance state (ON state) with the positive side and the negative side of the electrode layer 102 shown in FIG. A pulse voltage was applied.

Thereafter, the probe electrode was returned to the recording start point, and the recording layer 107 was scanned again. At this time, when reading out the record, adjustment was made so that Z = constant. As a result, it was shown that a probe current of about 10 nA flowed in the data bit, and the data bit was turned on.

After the probe voltage was changed from the ON state of the electric memory material to the OFF state by applying the pulse voltage shown in FIG. 7, the recording position was traced again. It was also confirmed that the state had changed.

[0041]

As described above, according to the present invention, the mother
Since an electrode substrate having tracks is manufactured by transferring a track pattern to an extremely smooth electrode surface reflecting the smoothness of the material,. It has become easy to mass-produce smooth electrode substrates having tracks, and it has become possible to reduce production prices. . Since the transfer material can be used repeatedly, the price can be reduced. . Since the track pattern is formed on the transfer material, the track pattern can be formed without impairing the smoothness of the base material. As a result, the area other than the tracks reflects the smoothness of the base material
Is extremely smooth and uses the principle of a scanning tunneling microscope.
Recording that can be used suitably for applied information processing devices
The medium can be easily manufactured.

[Brief description of the drawings]

FIG. 1 is a process chart of an electrode substrate manufacturing method according to the present invention.

FIG. 2 is a manufacturing process diagram according to the embodiment of the present invention.

FIG. 3 is a manufacturing process diagram in the example of the present invention.

FIG. 4 is a manufacturing process diagram in the example of the present invention.

FIG. 5 is a configuration diagram of an information processing apparatus to which STM is applied.

FIG. 6 is a diagram showing a waveform of an electric pulse required to cause a recording layer of a recording medium formed by the manufacturing method of the present invention to transition from a high resistance state to a low resistance state.

FIG. 7 is a diagram showing a waveform of an electric pulse necessary for returning a low resistance state portion on a recording layer of a recording medium formed by the manufacturing method of the present invention to a high resistance state again.

[Description of sign]

DESCRIPTION OF SYMBOLS 101 Substrate 102 Electrode layer 103 Transfer material 104, 104 'Track pattern 105 Adhesive 106 Peeling substrate 107 Recording layer 201 XY stage 202 Probe electrode 203 Probe electrode support 204 Z axis linear actuator 205XY which drives a probe electrode in the Z direction Linear actuator for driving stage in X direction 206 Linear actuator for driving XY stage in Y direction 301 Amplifier 302 Logarithmic compressor 303 Low-pass filter 304 Error amplifier 305 Driver 306 Drive circuit 307 High-pass filter

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshihiro Yanagisawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Haruki Kawada 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon (56) References JP-A-3-156749 (JP, A) JP-A-62-157327 (JP, A) JP-A-2-56749 (JP, A) JP-A-4-1951 (JP, A) A) (58) Field surveyed (Int. Cl. ⁶ , DB name) G11B 9/00

Claims (3)

(57) [Claims] 1. The method according to claim 1, wherein the substrate is on a cleavage plane of a crystal substrate or a molten glass substrate.
Step of forming a metal layer on a plate and a convex track pattern
The surface of the transfer material on which the pattern is formed faces the surface of the metal layer.
After placing and pressing on the transfer material, remove the transfer material.
A concave track pattern on the surface of the metal layer.
Transferring the concave track pattern
Forming a recording layer on the metal layer which has been formed.
The method of manufacturing a recording medium. 2. The method according to claim 2, wherein the substrate is on a cleavage plane of a crystal substrate or a molten glass substrate.
Forming a metal layer on a plate; and forming a substrate on the metal layer.
Bonding step and a metal layer bonded to the substrate
Of removing the crystal substrate from the substrate and a convex track putter
The surface of the transfer material on which the pattern is formed is
Placed opposite to the peeled surface and pressed from above the transfer material
Later, by removing the transfer material, the metal layer surface
Transferring a concave track pattern;
The recording layer on the metal layer to which the magnetic pattern has been transferred
And a method for manufacturing a recording medium. 3. The recording layer according to claim 1, wherein said recording layer is a Langmuir Brodget.
2. The method according to claim 1, wherein
3. The method for producing a recording medium according to any one of 2.