JPS63261554A - information storage device - Google Patents

Abstract

PURPOSE:To realize the ultra-high density recording and high speed reproduction of an information by setting a projection part on a memory medium face and providing a sensor of a space current in opposition to the medium face. CONSTITUTION:The atom. lump 2a formed on a substrate 1 is formed in the shape felling down a triangular column so as to enable to absorb its displacement with a probe 3 and the arrangement pitch of the atom. lump 2a line becomes of a signal. The substrate 1 coats a positive photo-resist in about 1,000Angstrom on the GaAs(110) face subjected to cleavage, executes a laser exposure for forming the guide groove 24 for tracking, exposes the GaAs face by subjecting the exposing part to chemical etching and removes the GaAs face by plasma etching to form a groove. Thereafter, the resist on the GaAs face is removed by plasma usher to form the substrate 1 having a groove 24. The atomic lump 2a as the memory unit of an information is obtd. by forming an Ag with its deposition on the GaAs face by the ion beam deposition restricted in a slit shape. Since the shape of the memory unit of the information can reach up to an atomic level, the drastical improvement in recording density is thus made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the storage and reproduction of information, and particularly to an information storage device suitable for ultra-high density information storage and high speed information transmission.

[Conventional technology]

2. Description of the Related Art As a recording (or storage) and reproducing method replacing magnetic disks and magnetic tapes, so-called optical disks, which optically record and reproduce information, have been put into practical use.

Supported by the rapid development of semiconductor lasers and the development of optical design technology, such optical discs have become commonly available in playback-only and write-once type discs (for example, "Introduction to Video Discs and DAD" written by So-Hato Iwamura). Published by Corona Publishing, November 1, 1981, see Chapters 6 and 10).

On the other hand, since the basic principle of these optical discs is to record and reproduce information using a beam of light focused close to the diffraction limit of light, the unit shape of information (so-called bit) must be at least 0.4 μm in size. However, the storage capacity can be increased by increasing the size of the optical disk.

Furthermore, when reproducing information recorded on an optical disc, the upper limit of the clock frequency is set at about 10 MHz due to restrictions on the rotational frequency of the disc and the pit shape.

[Problem that the invention seeks to solve]

In the above-mentioned conventional technology, although optical disk memory has a higher recording density than so-called magnetic memory, it is difficult to expect a significant increase in recording density due to the restriction of the diffraction limit of light (even with short wavelength lasers, There was a problem that the density was increased by 3 times.

Furthermore, no consideration was given to a significant increase in storage density, and there were also problems in terms of information reproduction speed.

SUMMARY OF THE INVENTION An object of the present invention is to provide an information storage device that performs ultra-high-density recording and high-speed reproduction (significantly improved transfer speed) of information that exceeds the limits of optical discs.

(Means for solving the problem) The above purpose is to set a protrusion made of minute atomic masses etc. on the surface of the memory medium, and install a space current (tunnel current) sensor (sample) opposite to this medium surface. This is achieved by

(Operation) The basic form of recognition for recording and reproducing information is whether a substance exists or not, and even miniaturization of substances, substance constituent crystals, atoms, electrons, etc. is allowed.

Therefore, by setting the presence or absence of atoms on a certain plane, the basic unit of information can be reduced (that is, the recording density can be improved).

The storage unit of information on an optical disk is approximately 0.4 μm (4000 μm).
In principle, the storage unit of information of the existence of atoms (approximately 2 human diameter) is 4X10' compared to an optical disk.
It is possible to double the density.

Therefore, a memory medium in which several or hundreds of atomic blocks are used as information storage units can be used as an ultra-high-density storage device.

FIG. 9 is a diagram explaining the principle of the present invention, in which an atomic mass 2 formed on a single crystal cleavage plane 1 is provided in a convex shape from the substrate plane 1 to the outer space, and the height Z from the atomic mass 2 and the substrate are A probe 3 for detecting the height Zo from the plane 1 is placed above the atomic mass (at a distance of approximately several tens of people).

Now, as an atomic mass, conductive metals such as Ni and Ag
When using , the conducting electrons in the metal are electrically bound within the metal by attractive force.

In order to overcome this attractive force and extract the electrons to the outside, energy (work function) exceeding a certain value must be applied.

Here, the tunnel current density JT that flows between metals separated by a distance Z by applying a voltage V with energy lower than the work function φ is the self-electron approximation, J, - (aβφ pot V/Z)
It can be expressed as exp (-a Zφ number), and J7
is an exponential function of the distance NZ. Here, a-4π(2m)
No./h=10.25nm-' (eV) cloudy, β-8"/4
rth (e is electric charge, m is electron mass, h is blank constant)
is a constant that is almost unaffected by the type of metal. In addition, Zo is the distance between the probe 3 and the substrate 1, and Zo >
It is z.

Therefore, since φ is 1 to 5 eV on the metal surface, changing the distance Z by 1 to 3 people will increase the tunnel current (electrical signal in space).
The difference is one finger.

FIG. 10 is a graph showing the tunneling current detected by the configuration shown in FIG. It is obtained as an exponential change in density J.

This basic principle is used, for example, in Nikkei Microdevices.

Tunneling microscope (STM) described in November issue, 1986, P, 81-97.
In STM, information on the atomic arrangement is obtained by adjusting the distance between the tip and the atoms so that the tunneling current is always constant, but in the present invention, the tunneling current exceeding a certain threshold is , can recognize the presence or absence of information.

In addition, in order to align the information storage unit with the position of the probe, concentric circles or spiral grooves or pit row tracks are provided, and the information storage unit is placed between or within the tracks, similar to when reproducing information from an optical disk. It is recommended to form a

By doing so, it is possible to easily employ an optical tracking method (utilizing the diffraction effect by grooves or pit rows) connected to the sensor.

However, in this case, the recording surface density remains about 103 times that of an optical disk, but a tracking method using tunnel current can also be easily achieved.

Furthermore, in order to improve tracking accuracy, the information storage unit is made into a wide protrusion, thereby eliminating the misalignment with the sensor position.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of an information storage/reproduction device using an information storage device according to the present invention, in which 1 is a substrate (substrate or 3 is a probe (sample or sensor) for tunneling current (electrical signal in space), 4 is a driving device for the probe 3, 5 is a detection amplifier circuit for tunneling current, 6 is a substrate (memory medium) rotation drive 7 is a signal recording/reproducing circuit; 8 is a laser light source used for coarse Z-axis adjustment between the probe 3 and the substrate 1; 9 is a half mirror; 110 is a condensing lens; 11 is a focusing lens;
It is a tracking adjuster.

In the figure, laser light from a laser light source 8 is focused on a groove formed in a substrate 1 via a half mirror 9 and a condensing lens 10, and the intensity of the diffracted light, which becomes a focus/tracking control signal, is detected by an optical sensor. The focus and tracking adjuster 11 has the following functions.

The focus/tracking adjuster 11 works in conjunction with the driving device 4 for the probe 3, and can perform two-axis alignment on the surface of the substrate by rough adjustment. Here, it is preferable that the focus/tracking adjuster 11 and the probe 3 be set on substantially the same track.

After that, the substrate 1 is rotated and a minute voltage is applied to the piezoelectric element (not shown) incorporated in the drive device 4 to make fine adjustments so that the tunnel current (unit signal source) from the atomic mass can be detected. Complete alignment.

FIG. 2 is a perspective view showing an embodiment of an information recording medium, in which 1 is a substrate (memory medium), 2a is an atomic mass, 3 is a probe,
24 is a guide groove, and 25 is a light spot area.

In the figure, the atomic masses 2a formed on the base Fil are formed in the shape of a tilted triangular prism so as to absorb the positional deviation with respect to the probe 3, and the arrangement pitch of the atomic masses 2a rows serves as a signal.

For the substrate 1, approximately 1000 positive photoresists were coated on the isolated GaAs (110) surface, and laser exposure (He-Cd, N- A-0, 9) L, the exposed portion is chemically etched to expose the GaAs surface, and the GaAs surface is removed by plasma etching to form a groove.

Thereafter, the resist on the GaAs surface was removed using a plasma asher to form the substrate 1 with grooves 24.

The atomic mass 2a as the information storage unit was obtained by depositing Ag on the GaA3 surface by ion beam deposition focused in a slit shape. The thickness of the film is preferably in the range of 10 to 500 because the thicker the film, the more the slit-like shape (displacement) becomes continuous and planar.

FIG. 3 is a block diagram showing an example of a device for forming micro atomic masses, in which an ion beam 1 emitted from an atomic ion source 12 is shown.
3 is turned on and off by a shutter 15 controlled by a signal source 14.

The ion beam that has passed through the shutter 15 is shaped into a predetermined shape by a multistage collimator 16 to form a micro atomic mass 2 on the memory substrate 1 .

The stage 17 of the memory board 1 is controlled to move in the direction of the arrow by a piezoelectric element 18 and a piezoelectric motor 19.

Here, in order to increase the recording density, it is necessary to reduce the width of the ion beam to 5 Å or less.

FIG. 4 is a configuration diagram showing an example of the collimator 16 having a multi-stage configuration.

In the figure, a slit 2 that can be slightly displaced by a piezoelectric element 21 is located between fixed slit groups 20a and 20b.
0c, and a probe 22 for atomic ions is provided in the slit 2°C, and a control circuit 23 controls so that the number of atoms flying to the probe 22 is always constant.

The ion beam flies in the direction from the slit 20a to 20b. Electric field in the direction of the arrow to focus the beam.

Applying a magnetic field is effective.

By setting the overlap of the slits in the slit group at different levels and by controlling the number of atoms that are slightly displaced and emitted from the collimator to a constant value, the ion beam can be sufficiently focused and controlled to a constant amount. Can form tiny atomic clusters.

Further, in FIG. 3, the memory substrate 1 is moved by a piezoelectric motor 19, and it is possible to move about 10 people, and it is possible to form an array of atomic clusters with extremely small pits.

Further, since the memory base l is configured to maintain a constant distance from the multi-stage collimator 16 using a displacement sensor (not shown) using the piezoelectric element 18, it is possible to form an atomic cluster array with high precision.

Here, the height of the atomic mass is preferably 10 to 500 people, because: ■ When the unevenness of the substrate surface is two atoms thick (approximately 2 people), the noise level is similar to the amplifier noise level (1,
7X 10-” A/30 KHz bandwidth), and the formation of atomic clusters of 0500 Å or more may cause shape abnormalities due to formation distortion of the atomic clusters (e.g., electromigration).
This is because it is easy to occur.

The information recording and reproducing device described above has the base 1 as described above! As a result of playback, it was possible to obtain a memory with a storage density approximately 103 times that of an optical disk.

In addition, when writing information, a voltage corresponding to energy φ4 larger than the work function φ is applied between the probe 3 and the atomic lump 2a, and several tens of atoms in the atomic lump 2a are evaporated in an electric field, thereby easily writing a signal. can.

As described above, according to the present invention, it is possible to record information at a higher density than the so-called striped optical disk, and the optical tracking method described in the embodiment can be replaced with other methods, such as tracking using tunnel current according to the present invention. It goes without saying that by adopting this method, even higher density is possible.

Further, although GaAs was used as the substrate material in one embodiment of the present invention, other conductive materials such as Ag may also be used.

Ni, AJ! and semiconductor materials such as St, chalcogenide compounds, etc. can be used.

Furthermore, the shape of the atomic mass as a unit of information storage is not limited to the horizontal triangular prism of this embodiment, and may be, for example, conical. In this case, the shape of the tip of the probe may be a triangular prism. Bye.

Furthermore, since tunnel current occurs both underwater and in the atmosphere, it is easy to replace the information storage medium.

FIG. 5 is a perspective view showing a method of adjusting the focus of the atomic mass 2a and the probe 3, in which the positions of the atomic mass 2a and the probe 3 are kept constant on a plane adjacent to the atomic mass 2a, which is a unit of information storage. In order to obtain a control signal to maintain, another atomic mass array 2b may be provided. Reference numeral 27 is a tunnel current probe for fine focus adjustment.

FIG. 6.7.8 is a conceptual diagram showing another row of tracking means, in which a plurality of probes 3a, 3b, and 3C are used to
Tracking control can be performed using the difference signal between the tunnel currents and 30.

〔Effect of the invention〕

As explained above, according to the present invention, the shape of the information storage unit can reach the atomic level, so it is possible to significantly improve the recording density and solve the problems of the above-mentioned conventional technology, such as miniaturization of the recording device. However, it is possible to provide an information storage device with excellent functionality.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of an information recording/reproducing device using an information storage device according to the present invention, FIG. 2 is a perspective view showing an embodiment of an information storage medium, and FIG. FIG. 4 is a block diagram showing an example of a forming device, FIG. 4 is a configuration diagram showing an example of a multi-stage collimator 16, FIG. 5 is a perspective view showing a focus adjustment method, and FIG. 6.7.8 is a diagram showing a tracking means. FIG. 9 is a conceptual diagram showing the other side, FIG. 9 is a diagram explaining the principle of the present invention, and FIG. 10 is a graph diagram showing detected tunnel current. 1... Subject (memory medium), 2...
... Atomic mass, 3 ... Specimen (sensor or probe), 4 ... Probe drive device, 5
......Tunnel current detection circuit, 8...
...Laser light source, 10...Condensing lens, 12...Atomic ion source, 16...
・・・・・・Collimator, 24・・・・・・Guide groove. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10

Claims (1)

[Claims] 1. In an information storage device that records information based on a difference in spatial distance between a specimen and a subject, the density of an electrical signal in space caused by a difference in the spatial distance between the specimen and the subject is A unit signal source is used, and information is recorded and reproduced by pre-set protrusions on the surface of the subject or by physically removing pre-set protrusions, thereby enabling ultra-high-density storage at the atomic level. information storage device. 2. In the information storage device according to claim 1, the storage unit of the information of the object is located on the plane of the object and is formed in a convex shape with a height in the range of 10 to 500 Å. An information storage device characterized by being an atomic mass. 3. In the information storage device according to claim 2, concentric or spiral grooves or pit rows are provided in the object as a means for scanning the atomic mass, which is the unit of storage of the information, and an optical An information storage device characterized in that information is recorded and reproduced by tracking. 4. In the information storage device according to claim 2, a signal source controls the atomic mass and the specimen to maintain constant positions on a plane adjacent to the atomic mass, which is the storage unit of the information. An information storage device characterized in that another atomic mass is provided as a. 5. In the information storage device according to claim 2, an electric field of φw or more is applied to the atomic lump of the information storage unit to evaporate a part of the atomic lump in the electric field to bring it into a recording state, An information storage device characterized in that information is recorded and reproduced by determining changes in tunnel current in an electric field.