WO2006070704A1 - High density information recording/reproducing/erasing method, and medium and apparatus used therein - Google Patents

Abstract

Orientation direction of fine particles, microcrystals and molecules composing a thin film is changed and information is recorded by virtually dividing the thin film into a multitude of fine regions, bringing a recording/reproducing needle having a sharp leading edge shape into contact with one of the fine regions (for instance, a fine region) and by moving the needle parallel to a surface of the thin film. For instance, information of “0” and “1” is recorded in every fine region by changing the internal structure in two states. The information is read by detecting an interaction force generated between the needle and the thin film, in a status where the recording/reproducing needle having the sharp leading edge shape is brought into constant or intermittent contact with the surface of the thin film.

Description

 Specification

 High-density information recording, playback, and erasing methods, and media and devices used therefor

 Technical field

 TECHNICAL FIELD [0001] The present invention relates to a high-density recording medium capable of recording information in a minute area of the order of 100 square nanometers, a recording apparatus thereof, and a recording, reproducing, and erasing method thereof. Background art

 [0002] In the field of memory, improvement in recording density is always required. For silicon semiconductor memory and magnetic disks, the recording density is expected to reach the limit of the force that has been improved according to Moore's Law. Therefore, there is a need for a new memory that operates on a principle different from the conventional one.

 [0003] As one of such memories, a memory applying the principle of a scanning tunneling microscope (STM) or an atomic force microscope (AFM) is being studied. For example, Patent Document 1 applies the STM principle, scans the surface of a polyimide LB film with a probe electrode, and records information at that position by applying a voltage of a predetermined value or more. Describes a device that can read (reproduce) the recorded information according to the strength of the tunnel current measured in. Non-Patent Document 1 applies the principle of AFM, applies a force in the vertical direction to the film surface with the AFM probe while the polymer film is heated, and checks the film surface in a concave shape. Information is recorded. In this case, information is read out by measuring the ruggedness on the film surface using an AFM device.

On the other hand, the inventor of the present application has studied a method for controlling the orientation characteristics of fine particles, microcrystals, or molecules in a minute region using an AFM apparatus. In Patent Document 2, force is applied using a member having a sharp tip shape such as (but not limited to) an AFM probe to the entire film during film formation or after film formation or in an arbitrary region in the film. In addition, it is described that the orientation direction of fine particles or microcrystals and / or molecules constituting the film is controlled. According to this document, for example, in polymer materials, polyethylene thin film, polytrifluoride steel In many thin films such as silicon thin films and vinylidene fluoride thin films, the AFM probe is scanned on the film surface to apply a mechanical force in the scanning direction. Alternatively, the molecular chain can be oriented in a predetermined direction.

 The result of the orientation control depends on the film temperature when the force is applied. The optimum temperature varies depending on the film material. Furthermore, even if the same film material is used, the optimum temperature is generally different between fine particle or microcrystal orientation control and molecular orientation control. In this regard, a thin film in which a lamellar microcrystal of a random copolymer of vinylidene fluoride and trifluoroethylene (P_ (VDF_TrFE)) is grown on a substrate so that the lamellar surface is oriented perpendicular to the substrate. Will be described as an example. While the thin film is heated, the force in the above-mentioned running direction can be obtained. When the heating temperature is 80 ° C, the microcrystal is rotated by the force applied by the probe force, and its long axis (perpendicular to the molecular chain axis) is arranged approximately parallel to the scanning direction. On the other hand, in the case of heating temperature force S135 ° C, the molecular chain is stretched in the direction of the tip of the probe and then folded and crystallized while maintaining the direction, so the c-axis (molecular chain axis) is Arrange substantially parallel to the scanning direction. Here, an organic polymer material has been described as an example, but the method described in Patent Document 2 can be applied to an organic low-molecular material such as an oligomer or a liquid crystal material. Furthermore, the present invention can be applied to an inorganic thin film composed of fine particles or microcrystals.

[Patent Document 1]

 Japanese Patent Laid-Open No. 6-187675 (published July 8, 1994) (in particular, [0052] to [0076], FIG. 4, FIG. 10 to 10)

 [Patent Document 2]

 International Publication WO2004 / 026459 (April 1, 2004) (Page 15, Line 26 to Page 17, Line 1, Line 7, Figures 2 to 6)

[Non-Patent Document 1]

 HJ Mamin et al., Applied 'Physics' Letters, (USA), American 'Institut Uto'ob' Physics, 1992, 61st, 1003 (HJ Mamin et al., "Thermomechanical writing with an atomic force microscope tip, Applied Physics Lette rs, 1992, vol. 61, p. 1003)

Disclosure of the invention [0006] The problem to be solved by the present invention is to enable high-density information recording, which is difficult with the prior art, by using a technique for controlling the orientation direction of fine particles or microcrystals and / or molecules in a minute region. It is to provide a new type of rewritable random access high density memory.

 [0007] A high-density information recording method according to the present invention for solving the above problems uses a member having a sharp tip shape in a minute region of a thin film formed on a substrate, and is parallel to the surface of the thin film. By applying force, the orientation direction of fine particles, microcrystals, or molecules in the minute region is changed, and information is recorded. As a method of applying a force parallel to the surface of the thin film, for example, a member having a sharp tip shape is in contact with the surface of the thin film regularly or intermittently, and the member is microscopically parallel to the film surface. By moving the distance or vibrating, it is possible to measure the force in the direction parallel to the film surface. Here, the “steady contact state” refers to a state in which the distance between the member and the membrane surface or the contact pressure is controlled to be constant. The “intermittent contact state” refers to a state in which the distance between them or the contact pressure is controlled so as to change periodically or aperiodically. (Hereinafter, “steady or intermittent contact” is used in the above-mentioned meaning in the present specification.) While maintaining the above state, the member is made minute in a direction parallel to the film surface. It shows that the force can be increased along the moving direction with respect to the film by moving the distance. It is also shown that force can be applied to the membrane along the direction of vibration by vibrating the member in a direction parallel to the membrane surface. Each of the above examples is an example that can realize a force parallel to the film surface.

 [0008] When the information is recorded in the minute area, the temperature of the minute area may be controlled by the contact pressure between the member and the film.

 [0009] Further, for example, when the thin film is made of a ferroelectric material, an electric field is applied to the minute region when the recording is performed, and the polarization in the minute region is changed to be superimposed on the information. Information can be recorded. Further, if the thin film is made of a ferromagnetic material, a magnetic field is applied to the minute area when recording is performed, and the magnetization in the minute area is changed to record different information superimposed on the information. You can also.

On the other hand, another high-density information recording according to the present invention made to solve the above-mentioned problems. In the recording method, in a small region of the thin film formed on the substrate, a temperature-controlled sharp tip shape is brought into contact with the surface of the thin film regularly or intermittently, and the temperature of the thin film surface is controlled. Information is recorded by changing the orientation direction of fine particles, microcrystals, or molecules in the minute region. Here, the orientation direction of the fine particles, microcrystals, or molecules in the minute region is controlled only by controlling the temperature of the thin film surface using a member having a sharp tip shape without applying a force parallel to the thin film surface. The technology to record the information is disclosed. By combining the above-described technology for recording information by temperature control and the above-described technology for recording information by applying force with a sharp shape, it becomes possible to realize a higher-density memory device.

 [0011] Further, in the high-density information recording method according to the present invention, it is preferable to record information of three or more values in one information recording area in the minute area of the thin film. According to this technology, multi-value information can be recorded in one information recording area, so that the recording density can be further increased.

 [0012] A recording medium used in the present invention is an information recording medium having at least a substrate and a thin film laminated on the substrate, and records information by the high-density information recording method described above. It is a high-density information recording medium capable of. Here, the thin film laminated on the substrate may be a single layer, or may be composed of a plurality of thin films laminated. In addition, a part of a plurality of laminated thin films may include a protective film that does not record information directly.

 Furthermore, information recording is performed using the above-described “recording method in which a force or heat in a direction parallel to the film surface is applied to a minute region of the thin film” and the above-described electric field or magnetic field. The thin films formed may be the same or may be separate films. In the latter case, one high density information recording medium can be formed by laminating the respective films. When laminating a plurality of films recorded using different recording methods as described above, it is important to place the film recorded using the above method on the outermost surface of the laminated medium. Is more effective.

[0014] In the high-density information reproducing method according to the present invention, a member having a sharp tip shape is contacted regularly or intermittently, and the member is minutely moved in a direction parallel to the film surface relative to the thin film. It is characterized in that it includes a step of reading the orientation direction of the fine particles, microcrystals or molecules in the microscopic region by detecting the force generated between the two when the distance is moved and / or vibrated. However, here, the direction of vibration in the case of “vibrating the member relative to the thin film” is not necessarily limited to a direction parallel to the film surface, and includes a direction parallel to the film surface and a direction perpendicular to the film surface. Includes all directions in three dimensions. This causes a change in the interaction force acting between the two and detects it.

 [0015] Further, the high-density information recording / reproducing method according to the present invention includes the above-described high-density information recording method as one step of information recording (information recording step), and includes the above-described high-density information reproducing method for information reproduction. It is included as one process (information reproduction process).

 [0016] Still other objects, features, and advantages of the present invention will be fully understood from the following description. The benefits of the present invention will become apparent from the following description with reference to the accompanying drawings.

 Brief Description of Drawings

 FIG. 1 is a cross-sectional view showing an embodiment of a high-density information recording apparatus according to the present invention.

 FIG. 2 (a) is a perspective view showing the operation of the high-density information recording apparatus of this example.

 FIG. 2 (b) is a perspective view showing another operation of the high-density information recording apparatus of the present embodiment.

 FIG. 3 is a cross-sectional view showing one embodiment of a high-density information recording apparatus having heating means.

 FIG. 4 is a cross-sectional view showing an embodiment of a high density information recording apparatus having an electric field applying means.

 FIG. 5 is a perspective view showing an information recording operation in a high-density information recording apparatus having electric field applying means.

 FIG. 6 (a) is a cross-sectional view showing an information recording operation in a high-density information recording apparatus having electric field applying means.

 FIG. 6 (b) is a cross-sectional view showing another operation of recording information in the high-density information recording apparatus having the electric field applying means.

 FIG. 7 (a) is a cross-sectional view showing the operation of reproducing information in a high-density information recording apparatus having electric field applying means.

FIG. 7 (b) is a cross-sectional view showing another operation of reproducing information in the high-density information recording apparatus having the electric field applying means. 7 (c)] A cross-sectional view showing another operation of reproducing information in the high-density information recording apparatus having the electric field applying means.

7 (d)] A sectional view showing another operation of reproducing information in the high-density information recording apparatus having the electric field applying means.

 FIG. 8 (a) is a view showing an AFM image of a P (VDF-TrFE) film 41 formed on a graphite substrate. 8 (b)] Perspective view schematically showing the P (VDF-TYFE) film 41 formed on the graphite substrate

FIG. 9 (a) is a view showing an AFM image of a P (VDF-TrFE) film 42 formed on a glass substrate.

9 (b)] A perspective view schematically showing a P (VDF-TYFE) film 42 formed on a glass substrate.

[FIG. 10 (a)] An AFM image after recording information by moving the recording needle parallel to the surface of the P (VDF-TrFE) film 41 heated to 140-145 ° C.

 [FIG. 10 (b)] An AFM image after recording information by moving the recording needle parallel to the surface of the P (VDF_TrFE) film 42 heated to 140-145 ° C.

 [Fig. 11 (a)] AFM image immediately after recording of P (VDF-TrFE) film with recorded information.

 [Fig. 11 (b)] AFM image of P (VDF-TrFE) film with recorded information after heating to 142 ° C.

11 (c)] After the information was erased by heating the P (VDF-TrFE) film on which the information was recorded to 148 ° C

AFM image.

[12] (a)] AFM image of P (VDF-TrFE) film in which information is recorded superimposed by applying force and electric field.

En 12 (b)] Piezoelectric power microscope image of P (VDF-TrFE) film in which information is recorded in a superimposed manner by applying force and applying electric field.

13 (a)] AFM image of the surface before applying force by moving the recording needle parallel to the surface of the polyethylene film.

13 (b)] AFM image of the surface after recording information was recorded by moving the recording needle parallel to the surface of the polyethylene film.

14 (a)] AFM image of the surface before applying force by moving the recording needle parallel to the surface of the polybutene film.

14 (b)] Records information by applying force by moving the recording needle parallel to the surface of the polybutene film. AFM image of the surface after processing.

En 15 (a)] After recording information by controlling the orientation of the microcrystals by applying force by moving the recording needle parallel to the surface while heating the P (VDF_TrFE) film to 80 ° C AFM image. 15 (b)] After recording the information by controlling the orientation of the microcrystals by applying force by moving the recording needle parallel to the surface while heating the P (VDF_TrFE) film to 80 ° C Schematic diagram of the structure.

 [Fig. 16 (a)] AFM image of P (VDF_TrFE) film with recorded information.

(En 16 (b)] The reproduction information obtained by obtaining the P (VDF-TrFE) film strength in which the information was recorded was imaged. Sono]] A diagram showing the relationship between the orientation direction of molecules and the torsional amplitude of the cantilever due to friction. [Explanation of symbols]

 10 ... High-density information recording medium

11 ... Stage

 12 · 'Stage moving device (moving in x, y, z direction)

 12a ... Coarse motion device

 12b ... Fine movement device

 13 ... Recording / playback needle

 14 ... leaf spring

 15 ... Dryino

 16 ... Detector

 17 Control unit

 18 ... Heater

 19 ... Thermometer

 21 ... micro area

 22 ... Vibration mechanism (provides vibration in x_y plane)

23… Vibration mechanism (provides vibration in z direction)

24 ... Outer frame (24a ... Upper part, 24b ... Lower part)

31 ... Electric field application means

41… P (VDF-TrFE) film (c-axis isotropically oriented in the film surface) 42 ··· P (VDF-TrFE) film (c-axis oriented perpendicular to the film surface)

 51 · · · Micro area where the recording needle is moved

 52 ... Minute area where the recording needle was not moved

 53… Area polarized by + 7V voltage

 54… Area polarized by -7V voltage

 BEST MODE FOR CARRYING OUT THE INVENTION

 In the high-density information recording of the present invention, the orientation direction of fine particles or microcrystals and / or molecules is changed in a minute region of an organic or inorganic thin film formed on a substrate, and information is recorded by that direction. To do. For example, by changing between two orientation states, it is possible to record information of “0” and 〃1 for each minute region.This thin film is the same as the thin film described in Patent Document 2. The orientation direction of fine particles or microcrystals and / or molecular chains is determined by contacting a member (recording member) having a sharp tip typified by an AFM probe regularly or intermittently with the thin film surface. In this state, the force can be controlled by increasing the force in the direction parallel to the thin film surface, as an example of means for applying the force parallel to the thin film surface, as described above. This can be achieved by moving a member having a simple tip shape in the membrane plane, and by applying a slight vibration in the in-plane direction, which is different from that in one direction. On the other hand, a means for applying a force parallel to the film surface It is not always necessary to move or vibrate the member on the membrane surface, for example, when a force parallel to the membrane surface is applied to the member using an external driving device, the member is elastically deformed. Even in this case, it is possible that the member can apply a force parallel to the film surface to the fine particles, microcrystals or molecules constituting the film. is there.

[0020] It is also possible to apply the above force by means such as propagating ultrasonic vibration that vibrates in a direction parallel to the film surface to the member using another external driving device. Also in this case, the tip position of the member does not need to move. Furthermore, it is possible to use a force other than mechanical force, for example, an electromagnetic force, as the force parallel to the film surface. In this case as well, the tip position of the member does not need to move. Here, “contact” means that the distance between the two is such that an atomic force works. [0021] The size of the minute area is not particularly limited, but is desirably as small as possible in order to increase the recording density.

 [0022] When controlling the orientation of molecules, the size of the region largely depends on the size of the tip diameter of the recording member. Therefore, in order to increase the recording density, a recording member having a small tip diameter is used. It is desirable. However, the recording density is not determined only by the tip diameter of the recording member, but also depends on the shape of the tip and the material of the film (recording medium). For example, even if the tip diameter is large, it is possible to apply a force parallel to the film surface to a part of the pole of the member tip by devising its shape. On the other hand, depending on the material of the film (recording medium), the orientation of a region wider than the tip diameter may be controlled by molecular self-organization. Therefore, for example, even when a recording member having a tip diameter of 10 mm is used, the size of the minute recording area can be made sufficiently smaller than the diameter of 10 mm by accurately selecting the tip shape and film material. Is possible.

 [0023] When the orientation of fine particles or microcrystals is controlled, the minimum recording area width is determined by the size of the fine particles or microcrystals. By using a film made of smaller crystals, higher density recording becomes possible.

 On the other hand, when the tip diameter of the recording member is large, there are advantages in terms of speeding up recording and erasing and ease of manufacturing the apparatus. For this reason, the tip diameter of the recording member can be appropriately selected according to the purpose.

[0025] During the recording, the above-mentioned orientation control can be performed more precisely by controlling the contact pressure between the recording member and the thin film and the film temperature of the minute region. In addition, when the recording member is moved or vibrated, it is possible to control the orientation more precisely by controlling the amplitude and frequency. In addition, the orientation can be controlled more precisely by controlling physical constants such as elastic constants of the material constituting the recording member. Further, when an electromagnetic force is applied through the recording member as a force parallel to the film surface, the amplitude and frequency of the electromagnetic force to be driven, and the dielectric constant, magnetic constant of the material constituting the recording member, etc. By controlling the physical constant, it is possible to control the orientation more precisely. In addition, when applying an ultrasonic wave through a recording member as a force parallel to the film surface, the ultrasonic frequency, amplitude, elastic constant of the material constituting the recording member, sound speed, etc. By controlling the physical constant, it is possible to control the orientation more precisely.

 [0026] The difference in orientation can be formed, for example, by a difference between a state in which the orientation of fine particles, microcrystals, or molecules is disordered and a state in which the orientation is 1J in a certain direction in the film surface. In addition, the orientation of the fine particles, crystallites, or molecules is aligned in the first direction in the film surface and in a second direction different from that in the film surface (for example, a direction rotated 90 ° from the first direction). It can be a difference from the arranged state.

 [0027] Furthermore, the direction of fine particles, microcrystals, or molecules differs in three or more directions within the film plane (for example, the first direction, the direction rotated 45 ° from the first direction, and the first direction 90 It is also possible to record information by distinguishing three or more states arranged 1J in the direction of rotation). As a result, information of three or more values can be recorded in one area (information recording area). Therefore, according to the present technology, multilevel recording of information is possible, and the recording density can be further increased.

 [0028] In the above description, the orientation direction of the fine particles, microcrystals, or molecules is described only within the film plane. However, including up to the direction perpendicular to the film plane, the vertical direction and any angle such as 30 °, 60 °, etc. Orientation in the direction can be considered, and depending on the material composing the film, three-dimensional orientation control is possible. In fact, in many polymer materials such as polyethylene, the molecular chain can be oriented perpendicular to the substrate by heating to a temperature above the melting point. Therefore, as an example, a molecular member in a minute region can be oriented perpendicular to the substrate by bringing a recording member heated to a temperature equal to or higher than the melting point into contact with the film surface regularly or intermittently. In this case, a force parallel to the film surface cannot be applied during recording. The information recording may be performed using one recording member or a plurality of recording members. When a plurality of recording members are used, higher speed recording is possible.

 [0029] The recorded information can be reproduced using a member (reproduction member) having a sharp tip shape similar to that of the recording member. The same member can be used for recording and reproduction, and different members can be used. Further, reproduction may be performed by using a plurality of members to function simultaneously. An example of the reproduction method is shown below. First, a reproduction method in the case where information is recorded so that anisotropy of the orientation of fine particles, fine crystals, or molecules within the film surface will be described.

[0030] One direction in the film surface with the regeneration member in contact with the film surface constantly or intermittently The reproducing member receives an interaction force in the vibration direction from the molecules, fine particles, or microcrystals by moving the microscopically by a minute distance or microvibrating in the film surface or in other directions. Therefore, the reproducing member is influenced by the induction of torsion when moving a minute distance, and by the attenuation of vibration amplitude and the delay of phase when applying vibration. By detecting these physical quantities, the distribution of the magnitude of the interaction force in the direction of these forces can be measured. The present invention reads out the orientation method of fine particles, microcrystals or molecules based on the magnitude of these interaction forces.

 [0031] These physical quantities are obtained by, for example, an optical lever method in which a part of the reproducing member is irradiated with light and the vibration state of the reproducing member is monitored from the reflected light, or a piezoelectric part is applied to a part of the reproducing member. It is possible to measure with the piezoelectric method that monitors the vibration state of the regenerative member from the output.

 [0032] Within the surface of the recording medium, the reproducing member can be moved to a minute area from which information is to be read, and then the information in the minute area can be read out using the method described above. It is also possible to sequentially read information recorded in the entire area using the above method while scanning the entire surface of the recording medium.

 [0033] In the above example, the reproduction member is vibrated in one direction in the plane and reproduction is performed only from the response. However, reproduction is performed by combining information obtained by vibrating in a plurality of different directions in the plane. Thus, the reproduction accuracy can be improved. In that case, detection can be performed in parallel using a plurality of reproducing members. It is also possible to perform reproduction in chronological order using a single reproduction member. In the above example, the recording medium is fixed and the reproducing member is vibrated, but conversely, the recording medium may be vibrated.

Next, a description will be given of a reproducing method in the case where information recording is performed depending on whether fine particles, microcrystals, or molecules are oriented in a direction perpendicular to or parallel to the film surface. In this case, for example, vibration in a direction perpendicular to the film surface is applied from the back surface of the film by a method of providing a vibration element on a stage for fixing the recording medium. The vibration propagates inside the film and then appears on the surface of the film, but when propagating inside the film, it undergoes changes according to the characteristics of the film. Therefore, the amplitude and phase of the transmitted vibration are measured on the membrane surface by the reproducing member. In general, mechanical vibration is less damped in the polymer chain direction and propagation speed is faster. Les, it is known. Therefore, by comparing the amplitude and phase of the vibration detected by the reproducing member with those of the original vibration, the difference between the vertical alignment and the horizontal alignment can be detected. On the other hand, it is also possible to detect the difference between the vertical alignment and the horizontal alignment by vibrating the reproduction member in a direction perpendicular to the film surface in contact with the film surface and measuring the phase change. .

[0035] In the case where information is recorded due to a difference in polarization superimposed on a difference in orientation of fine particles, microcrystals, or molecules, for example, a conventionally known piezoelectric response scanning microscope (Piezoresponse Scanning) Force Microscopy re-reading power is ⁵ times (for the piezoelectric response scanning microscope, see, for example, Surface science letters, Vol. 302, p. L 284). Alternatively, when information is recorded by a difference in magnetization superimposed on a difference in orientation of microcrystals or molecules, for example, a reproducing member having a magnetoresistive sensor at the tip is used, and a stray magnetoresistive microscope is used. (Scanning Magnetic Resonance Microscopy) can be used to read out information (For example, see Applied Physics Letters, Vol. 80, No. 15, pp. 2713-2715 (2002) for scanning magnetoresistive microscopes) .

[0036] AFM tips with a tip diameter of 10 are widely available on the market. When this AFM probe is used as a recording member, as described above, the size of the minute recording area can be reduced to 10 nm xlOnm or less. That is, the high-density information recording medium according to the present invention can record lbit information in an area of 10 nm × 10 nm or less using an existing recording member. In this case, the recording density is lTbit / cm ^2. That's it. Further, the recording density can be further increased by producing a recording needle having a small tip diameter and optimizing the tip shape. Further, as described above, the orientation direction of fine particles or microcrystals and / or molecules in one minute recording region can be selectively oriented in a plurality of directions within the film surface. Furthermore, by selecting the material of the recording medium, it becomes possible to perform the alignment in the direction perpendicular to the film surface, and the alignment direction can be selected three-dimensionally. Thereby, the recording density is further improved. If n orientation directions can be selected, the recording density is log2n Tbit / cm ² . In addition to the above, the recording density is further increased by selecting a ferroelectric material or a ferromagnetic material as the recording medium as described above and superimposing and recording information based on a difference in polarization or a difference in magnetization. [0037] By performing heating, electric field application, magnetic field application, etc. on at least a part of the information recording area of the recording medium, the recorded information without using the recording member is erased collectively (memory medium). Can be initialized). For example, in the case of polymers such as polyethylene and P_ (VDF-TrFE), the orientation of the molecules can be controlled in a certain direction by heating above the melting point, and the regularity of changes in the molecular orientation is canceled and recorded. Information can be deleted at once. Examples of the heating method include performing with a heating element provided on a stage holding a recording medium. In addition, information recorded by applying an electric field or magnetic field can be overwritten with a single information by applying an electric or magnetic field in a certain direction to at least the recording area, and the information can be erased collectively. On the other hand, erasing the described information is performed by using the member having a sharp tip shape with respect to the entire information recording area of the recording medium and using the information recording method described in at least any one of 4 above. This can also be done by overwriting the information. In any of the above erasing methods, the applied force, heat, electric field, magnetic field, etc. may be performed individually or sequentially in time series, or a plurality of means may be combined in any combination. You may do it at the same time. Further, erasure of information may be performed using a single member or a plurality of members. When a plurality of members are used, faster erasing is possible.

 [0038] As the thin film material of the present invention, an organic low-molecular material, oligomer material, polymer material, or the like can be used. Among organic low-molecular materials, materials having anisotropy in their molecular shapes, such as liquid crystal materials, are useful. Also useful are low-molecular materials that have the ability to self-assemble. Furthermore, not only organic materials but also inorganic crystalline materials, metals, ceramics, etc. can be used. In particular, inorganic ferroelectric microcrystals and fine particles, and thin films made of paramagnetic or ferromagnetic metal or ceramic microcrystals or fine particles are useful as recording media for use in the present invention. As materials constituting the ferroelectric microcrystals and fine particles, for example, inorganic materials such as barium titanate, lead titanate, potassium hydrogen phosphate, Rossier salt, glycine sulfate, sodium nitrate, and thiourea are used. Can. In addition, as a material constituting the ferromagnetic metal or ceramic microcrystals or fine particles, for example, metals such as nickel, iron, and cobalto are useful. Further, organometallic complexes having magnetism are also useful.

[0039] Examples of the organic polymer material include polyethylene resin, polypropylene resin, and polyolefin. 4-methylpentene-1 resin, which is a phen resin, polybutene-1 resin, polybutyl alcohol, ethylene monovinyl alcohol copolymer, polyataryl nitrinole, polybutadiene, polyisoprene, polyamide resin, polyethylene terephthalate Polyester resin typified by butylene terephthalate, polytetrafluoroethylene, polytrifluoroethylene (PTrFE), polyvinylidene fluoride (PVDF), copolymer of polyvinylidene fluoride and polytrifluoroethylene (P (VDF- TrFE)) fluorinated resins such as polysalt-bulu, polysalt-biurydene, polyatalylate, polymetatalylate, polycarbonate, polystyrene, phenol resin, urea resin, melanin resin, alkyd resin, acrylic resin, Epoxy resin, silicone resin, polyimide resin Wholly aromatic polyamide known as Aramido resin, Porifue two Rene one ether, Porifue two Rensurufuido, polyarylate, poly - p_-phenylene, poly _p - xylene

, Poly-p-phenylenevinylene, polyquinoline, polypyrrole, polythiophene, polyaniline

, Polyarylene vinylene, polyphenylene vinylene, polyacetylene, polyphenylene diamine, polyaminophenol, polyvinyl carbazole, polymer viologen, polyion complex, TTF-TCNQ, and the like. In addition, materials composed of organic low molecules or organic oligomers which are constituents of these polymers may be used. Materials such as polymer liquid crystals and oligomer liquid crystals are also useful.

 [0040] As the substrate of the present invention, a substrate made of a conventionally known substrate material can be used.

Although not particularly limited, it is particularly preferable that the substrate surface on which the thin film is formed be a substrate having a symmetric crystal structure. Specifically, a substrate having such a surface is, for example, a graphite, My force, sapphire, NaCl, KC1, KBr, SiC

, ΒΝ, GaN, AIN, GaAs and the like. In the case of the above-described substrate, since the thin film molecules and crystals formed on the surface of the substrate are likely to grow epitaxially, the orientation can be controlled with high accuracy. Therefore, there is an advantage that a writing error hardly occurs when information is recorded. The thin film crystal grown on the substrate can be formed by suitably using a conventionally known method such as vapor phase epitaxy, liquid phase epitaxy, molecular beam epitaxy, etc., depending on the material, form, conditions, etc. of the raw material. it can.

[0041] Depending on the material used as the recording medium, by increasing the temperature of the thin film during the recording, the orientation of the fine particles, microcrystals or molecules using the recording member is facilitated, and the higher the temperature. Accurate orientation control may be possible. In particular, in order to improve the orientation controllability of the microcrystal, it may be effective to heat the thin film material to a temperature higher than the glass transition temperature. In order to improve the molecular orientation controllability, it may be effective to heat to a temperature close to the melting point of the thin film material. Since these conditions vary depending on the characteristics of the materials used as the recording medium, it is important to select the optimum conditions individually.

 [0042] It is particularly useful to use a polymer material having ferroelectricity as a material constituting the thin film. In this case, if the electric field is applied at the same time when the information is recorded in the micro area by the above method or at a time different from the recording by the orientation control, and the presence / absence and direction of the electric field are controlled, the micro area is controlled. The presence / absence or direction of the polarization of the region can be controlled. As a result, information can be recorded by polarization independently of the information recording by orientation control, and information can be recorded at a higher density. In this case, the same recording member used for the orientation control may be used as the recording member for recording the polarization information, or a different recording member may be used.

 [0043] For the same thin film, recording by molecular or amorphous orientation control and recording by polarization or magnetization state control may be performed independently of each other. Therefore, the micro area where information is recorded by the internal structure of the thin film and the micro area where information is recorded by polarization or magnetization do not have to be the same. For example, the micro area where information is recorded by polarization may be larger than the micro area where information is recorded by the internal structure.

 [0044] Ferroelectric polymer materials include, for example, vinylidene fluoride polymer (PVDF), oligomers, vinylidene fluoride copolymers represented by random copolymers of vinylidene fluoride and trifluoroethylene, nylon 7, An odd number nylon such as nylon 9, nylon 11 and nylon 13, or an alternating polymer of cyanobiridene and butyl acetate can be used.

Further, the present invention includes the above-described high-density information recording method as one step of information recording (information recording step), and the above-described high-density information reproducing method includes one step of information reproduction (information reproducing step). The high-density information recording / reproducing method is included. Here, the high-density information recording / reproducing method includes a case where the information recording process and the information reproducing process are performed at different places and times. For example, the information recording process is performed at a predetermined place and time, and thereafter, the information reproducing process is performed at a place different from the predetermined place with a time interval. It may be broken. Furthermore, the present invention may include a case where the information recording process and the information reproducing process are performed by different entities.

 The rewritable random access memory using the high-density information recording method, reproducing method and erasing method described so far can be implemented by the following apparatus. That is, the high-density memory device according to the present invention is an information recording / reproducing device for recording information at a high density on an information recording medium including a thin film formed on a substrate and further reproducing the information. A member having a flexible tip shape, a recording medium necessary for moving the member to each address position in the memory, and a moving mechanism for relatively moving the member, and further, x, a fine movement mechanism for finely changing the relative position in the y and z directions, and a mechanism for controlling the temperature of the member. Here, only one member may be provided for both recording and reproduction, or a recording member and a reproduction member may be provided separately.

 [0047] In this apparatus, as described above, the recording member is moved to the position of the minute region of the information recording medium, and the member is in constant or intermittent contact with the film surface at that position. A force that applies a force in a predetermined direction within the film surface or a force that vibrates in a predetermined direction within the film surface is applied to the member. As a result, the orientation direction of the fine particles, microcrystals or molecules constituting the film is changed, and information is recorded. Further, as described above, when ultrasonic vibration or electromagnetic force is used as a force for changing the orientation direction of fine particles, microcrystals, or molecules, an external force is applied to the recording member. Carry out the drive. In addition, the apparatus can also control the orientation direction of the crystal or molecule by controlling only the temperature of the minute region using a recording member.

 In reproducing information, the reproducing member is brought into contact with a minute region of the information recording medium regularly or intermittently, and then the member and / or the recording medium are moved by a minute distance in a direction parallel to the film surface. Alternatively, by oscillating one or both of the two, the force generated between the two is detected, and the orientation direction of the fine particles, microcrystals, or molecules in the minute region is read out.

[0049] When recording information by controlling the orientation of fine particles, microcrystals, or molecules of a thin film and recording information by polarization are superimposed, an electric field for applying an electric field to the thin film is further added to the high-density information recording apparatus. An application means is provided. [0050] Similarly, when recording information by controlling film orientation and recording information by magnetization are performed in a superimposed manner, magnetic field applying means for applying a magnetic field to the thin film is further provided.

 (The invention's effect)

By using the high-density information recording method, reproducing method, and erasing method according to the present invention, a large-capacity rewritable random access memory exceeding 1 Tbit m ² can be realized.

[0051] Further, by using a film having ferroelectricity or ferromagnetism, information recording by dynamic force and information recording using ferroelectricity or ferromagnetism can be performed independently and superimposed. Therefore, the information recording density can be further increased. Furthermore, the large-capacity memory realized by the present invention may be a rewritable memory or a random access type memory.

 〔Example〕

 Here, first, (1) an embodiment of a high-density memory device according to the present invention will be described, and the operation of this device will be described to explain the high-density information recording method according to the present invention. Next, (2) examples of the information recording method, the erasing method, and the high-density memory (recording medium) according to the present invention will be described based on experimental results. Furthermore, (3) As examples of the information reproducing method according to the present invention, various results of information recording and reproduction using these information recording media are shown.

 (1) Embodiment of high-density memory device according to the present invention

 (1-1) High-density memory device having basic configuration and its operation

 (1-1-1) Configuration of high-density memory device

FIG. 1 shows a cross-sectional view of one embodiment of a high-density memory device according to the present invention. This high-density memory device includes a stage 11 on which the high-density information recording medium 10 according to the present invention is placed, a stage moving device 12 that moves the stage 11 in the x, y, and z-axis directions, and a sharp tip shape. And a Si panel panel 14 having recording and recording / reproducing needles 13. Here, the X-axis and y-axis directions are directions parallel to the surface of the high-density information recording medium 10, and the z-axis direction is a direction perpendicular to the high-density information recording medium 10. The stage moving device 12 is composed of a two-stage moving device, a coarse moving device 12a and a fine moving device 12b. The stage moving device 12 is driven by a driver 15. Here, the fine movement device 12b can be used in the X-axis direction, the y-axis direction, and the z-axis It can be vibrated at the required frequency in the direction. The apparatus further includes a cylindrical outer frame 24 that fixes the above-described parts. The outer frame 24 is divided into an upper part 24a and a lower part 24b, and the leaf spring 14 and the detection unit 16 described later are fixed to the upper part 24a, and the stage 11 and the stage moving device 12 are fixed to the lower part 24b. The outer frame 24 includes a mechanism in which the upper part 24a can rotate 360 degrees in the x_y plane with respect to the lower part 24b. With this mechanism, the plate panel 14 can be rotated in any direction within the x_y plane about the recording / reproducing needle 13.

 The high-density memory device further includes a detection unit 16 for detecting a force acting on the plate panel 14. The driver 15 and the detection unit 16 of the stage moving device 12 are controlled by the control unit 17. The driver 15 changes the relative position between the stage 11 and the recording / reproducing needle 13 and changes the contact pressure between the two by adjusting the distance in the z-axis direction between the two. This contact pressure can be set according to the material of the high-density information recording medium 10.

 As a mechanism for reproducing information, a mechanism 22 that vibrates the recording / reproducing needle 13 in the x_y plane and a mechanism 23 that vibrates in the z direction are provided at the base of the leaf spring 14.

 [0055] As each of these unit devices, those provided in a normal AFM device can be used as they are. For the fine movement device 12b, for example, a piezoelectric element can be used. The detector 16 can be a detector that detects the displacement of the plate panel 14 by an optical method such as an optical lever method or a laser interference method. In addition, a cantilever used in AFM or STM can be used as a plate panel with a recording / reproducing member. In this case, by using a self-detection type cantilever such as a piezoelectric type or a piezoresistive type, a detection system such as the above-mentioned optical lever method or laser interference method becomes unnecessary.

 [0056] (1-1-2) Operation of high density memory device (during recording)

First, an operation for recording information will be described. The film constituting the high-density information recording medium 10 is virtually divided into a large number of minute regions. When information is recorded in one of these many micro areas (here, micro area 21 in the figure), the recording / reproducing needle 13 is arranged immediately above the micro area 21 by the stage moving device 12. In this way, the stage 11 is moved in the X-axis direction and the y-axis direction (Fig. 2 (a)). Then, the stage 11 is moved in the z-axis direction, and the high-density information recording medium 10 and the recording / reproducing needle 13 are brought into contact with each other regularly or intermittently. And as an example, by moving the stage 11 in a predetermined direction by a minute distance, A force in the direction opposite to the moving direction (when the recording / reproducing needle 13 is moved or vibrated with the minute area 21 fixed, the moving direction) is applied to the high-density information recording medium 10 (FIG. 2 ( b)). As a result, the orientation direction of the fine particles, microcrystals, or molecules constituting the film in the minute region 21 can be changed, whereby information such as “(Τ, 〃 ′” can be recorded.

 [0057] (1_1_3) Operation of high-density memory device (during playback)

 The information described in the micro area 21 can be reproduced using the following method. The recording / reproducing needle 13 is disposed immediately above the minute area 21 using the same mechanism as that used for recording. Next, the stage 12 is moved in the ζ-axis direction, and the high-density information recording medium 10 and the recording / reproducing needle 13 are brought into contact with each other. Next, for example, using the vibration mechanism 22, the recording / reproducing needle 13 is vibrated in a specific direction parallel to the recording medium surface. At this time, the magnitude of the force that the recording / reproducing needle 13 receives from the surface of the recording medium is detected by the detection unit 16 as the magnitude of the twist of the plate panel 14. In the above example, the recording / reproducing needle 13 is vibrated using the vibration mechanism 22, but even if the recording medium is vibrated using the fine movement device 12 b, it may be detected as the amplitude and phase of the twist of the plate panel 14. Yo! The vibration direction described as “specific” in the above can be set to any direction. In addition, it is possible to reproduce information with higher accuracy by using data oscillated in different directions for one minute region.

 Furthermore, the following method is also effective as another method for detecting the orientation direction of fine particles, microcrystals, or molecules. While the recording / reproducing needle 13 is vibrated in the z-axis direction using the vibration mechanism 23, the stage 11 is used to approach the recording medium surface, and the recording / reproducing needle 13 is positioned so as to intermittently contact the recording medium surface. In this state, the recording / reproducing needle 13 is torsionally vibrated in a specific direction parallel to the surface of the recording medium using the vibration mechanism 22 or the fine movement device 12b, and the magnitude of the force that the recording / reproducing needle 13 receives from the surface of the recording medium is measured on the plate panel. It is also possible to detect using the detector 16 as a signal of the magnitude and phase of 14 twists.

[0059] Furthermore, the following method is also effective as another method for detecting the orientation direction of fine particles, microcrystals, or molecules. The stage 11 is moved in the z-axis direction, and the high-density information recording medium 10 and the recording / reproducing needle 13 are brought into contact with each other. Next, when the recording / reproducing needle 13 is moved by a minute distance in the direction perpendicular to the long axis of the plate panel 14, the plate panel receives a twisting force. Information can be reproduced by detecting the amplitude information of the torsion signal by the detection unit 16. [0060] When information recording is performed depending on whether the orientation direction of fine particles, microcrystals, or molecules is perpendicular or horizontal to the film surface, the orientation information is reproduced using the following method. it can. First, the recording / reproducing needle 13 is arranged immediately above the minute region 21 using the same mechanism as in the above example. Next, the stage 11 is moved in the z-axis direction, and the high-density information recording medium 10 and the recording / reproducing needle 13 are brought into contact with each other. In this state, the recording medium is vibrated in the z-axis direction using the stage 12. After propagating through the recording medium, the amplitude and phase information of the vibration transmitted to the recording / reproducing needle 13 is detected using the detection unit 16. This makes it possible to regenerate whether the orientation direction of the fine particles, microcrystals, or molecules is perpendicular or horizontal to the film surface.

 [0061] Further, the recording / reproducing needle 13 is intermittently brought into contact with the surface of the recording medium by using the stage moving device 12 while vibrating the recording / reproducing needle 13 in the z-axis direction using the vibration mechanism 23. Whether the orientation direction of the fine particles, microcrystals, or molecules is perpendicular to the film surface or horizontal by reading the phase information of the vibration of the plate panel 14 in this state using the detection unit 16 Can also be played.

 [0062] In order to erase the information described in the minute area 21, all the recorded minute areas may be moved in the same direction by the recording / reproducing needle 13 so that all the areas are in the same state. Further, the recording state may be changed in the entire area by heating the entire thin film to a predetermined temperature or higher.

 In the above embodiment, the same member (recording / reproducing needle 13) is used for both recording and reproduction. However, a recording needle and a reproducing needle may be separately prepared and used separately.

 [0064] (1-2) High-density information recording and reproducing apparatus having heating means

 When the high-density information recording medium 10 is heated at the time of information recording as described above, as shown in FIG. 3, the recording / reproducing needle 13 is further connected to the high-density information recording apparatus of FIG. A heating means (heater) 18 for heating and a thermometer 19 for measuring the temperature of the recording / reproducing needle 13 are provided. The control unit 17 feeds back the measurement result of the thermometer 19 and controls the output of the heater 18 so that the recording / reproducing needle 13 has a temperature suitable for recording and / or erasing. Other configurations and operations are the same as those of the high-density information recording apparatus of FIG.

As the heating means, a laser light source for irradiating the recording area with laser light may be used instead of the heater 18 of the present embodiment. Also, like the heater 18 and laser light source, the recording area is localized. Instead of the heating means for heating the medium, a medium for heating the entire high-density information recording medium 10 may be used. In this case, the heating temperature can be easily controlled by only the portion where the force is applied by the recording / reproducing needle 13, and the orientation of the other portions is not changed by the temperature alone. Set to value.

(1-3) High-density information recording and reproducing apparatus having electric field applying means

 In addition to the control of fine particles or microcrystals and Z or molecules constituting the film of the high-density information recording medium 10, information is recorded by applying an electric field using the high-density information recording medium 10 having a ferroelectric film force. When performing, as shown in FIG. 4, an electric field applying means 31 is further provided in the high-density information recording apparatus of FIG. The electric field applying means 31 applies a positive or negative DC voltage corresponding to the value between the recording / reproducing needle 13 and the stage 11 at the time of recording information and an AC voltage at the time of reproducing.

 The operation of this high density information recording apparatus will be described. Similarly to the above, the recording / reproducing needle 13 is brought into contact with the minute region 21 by the stage moving device 12. Then, using the electric field applying means 31 and the recording / reproducing needle 13 having conductivity, for example, the stage 11 is moved in a predetermined direction while applying a positive or negative DC voltage between the recording / reproducing needle 13 and the stage 11. (Fig. 5), the mechanical force in the direction opposite to the moving direction of the stage 11 (the moving direction when moving the recording / reproducing needle 13 with the minute area 21 fixed) and the DC power The force from the field is applied to the high-density information recording medium 10. As a result, in the minute region 21, fine particles, microcrystals, or molecules change according to the moving direction of the recording / reproducing needle 13, and polarization induced by the applied DC electric field is generated. Recorded independently

In this high-density information recording apparatus, an electric field is simply applied without applying a mechanical force to the high-density information recording medium 10 (that is, without using the present invention at the time of recording). By doing so, information can also be recorded. In this case, after the recording / reproducing needle 13 is in contact with or close to the area (recording area) of the high-density information recording medium 10, a positive or negative value is placed between the stage 11 and the recording / reproducing needle 13 without moving the stage 11. Apply DC voltage. When a positive DC voltage is applied, the downward polarization P1 is in the recording area (Fig. 6 (a)). When a negative DC voltage is applied, the upward polarization P2 is (Fig. 6 (b)). Each formed 2 Value information is recorded by the direction of polarization. Independently, by applying a mechanical force by the method described in (1-1) or H-2), fine particles or microcrystals and / or molecules constituting the thin film are controlled. Information can also be recorded. That is, in the high-density information recording apparatus according to the present invention, information recording by the dynamic force according to the present invention and information recording using an electric field by a conventional method are performed on the same high-density information recording medium 10. Ability to do it independently.

 [0069] Information can be reproduced by detecting the direction of polarization. As shown in FIG. 7 (a) to FIG. 7 (d), the recording / reproducing needle 13 having conductivity is brought into contact with the recording area of the high-density information recording medium 10 regularly or intermittently, and the recording / reproducing needle 13-stage. Apply an AC voltage across 11. In the polarized region, application of alternating voltage causes the film thickness to expand and contract due to the piezoelectricity in the film thickness direction. This vibration can be detected as vibration in the z direction of the recording / reproducing needle 13 having conductivity. The frequency of this piezoelectric vibration is the same as the frequency of the applied voltage. By measuring the phase of both, the polarization direction of the film can be detected.

Information can be erased by polarizing the entire information recording area in the same direction by the above-described recording method using the recording / reproducing needle 13. Further, the recording force can be erased by applying an electric field in the same direction to at least the entire information recording area of the recording medium without using the recording / reproducing needle 13. A specific method of the latter can be realized by placing a recording medium between two parallel plate electrodes and applying a voltage of a certain value or more between the electrodes.

 (2) Examples of information recording method, erasing method and high-density memory (recording medium) according to the present invention Next, polyvinylidene fluoride as an example of a film usable as the high-density memory according to the present invention A polytrifluorinated styrene copolymer (P (VDF-TrFE)) film, a polyethylene film, and a polybutene film will be described below.

[0071] (2-1) Information recording by molecular orientation control (P (VDF-TrFE) film is used as a recording medium)

A solution prepared by dissolving P (VDF-TrFE) in methyl ethyl ketone (MEK) was spin-coated on a graphite substrate, and then heat-treated at 140 ° C. As a result, as shown in FIG. 8 (a) AFM image and FIG. 8 (b) perspective view, a lamellar microscopic structure in which the c-axis (molecular chain axis) is isotropically arranged 1J within the film surface. As a result, a P (VDF-TrFE) film 41 made of crystals and having a thickness of about lOOnm was obtained. Even if a glass substrate or a metal substrate such as aluminum, gold, or platinum is used instead of the graphite substrate, as long as it is crystallized at 140 ° C, it is shown in Figs. 8 (a) and 8 (b). A thin film having a thickness of about 150 mm having the same microcrystals as shown was obtained. On the other hand, when the glass substrate and the film formed on the metal substrate are heated to a temperature (160 ° C) sufficiently higher than the melting point (147 ° C), Fig. 9 (a) AFM image and Fig. 9 (b) oblique view. As shown in the figure, a P (VDF-TrFE) film 42 having a film thickness of about 150 nm was obtained in which the c-axis of the lamellar microcrystal was arranged 1J perpendicular to the film surface.

 [0072] The P (VDF-TrFE) film shown in Figs. 8 (a), 8 (b), 9 (a), and 9 (b) is slightly lower than the melting point (147 ° C). While the film was heated to 140 to 145 ° C., the recording needle was brought into contact with the surface of the film with a needle thickness of 2 nN to 30 nN. In this state, it was moved at a speed of 4 micrometers / second parallel to the film surface, and a horizontal force was applied to control the orientation of the molecules, and information was recorded. Figures 10 (a) and 10 (b) show AFM images (taken at a temperature of 30 ° C) of the film surface after information recording. Here, the recording needle was moved within the minute region 51 in the figure. The direction of the force applied during recording is indicated by arrows in the figure. In both Fig. 10 (a) P (VDF-TrFE) film 41 and Fig. 10 (b) P (VDF-TrFE) film 42, the c-axis (molecular chain axis) is recorded for the microcrystals in the minute region 51. Allocated in the direction of needle movement. On the other hand, the microcrystals were not arranged in the region 52 where the recording needle was not moved. In this way, the arrangement of the microcrystals can be controlled for each minute region by moving the recording needle, and thus information can be recorded for each minute region.

 [2-2] (2-2) Deletion of recorded information (P (VDF-TrFE) film is used as a recording medium)

A film is formed on the graphite substrate by the same method as in Example (2-1), and then molecular orientation is performed using the same method as in Example (2-1) while being heated to 142 ° C. Recorded information. Figure 11 (a) shows an AFM image of the film surface observed at 30 ° C after recording information. The area surrounded by the dotted line is an area 51 where information is recorded by controlling the molecular orientation by applying a force in the direction of the arrow using a recording needle. Figure 1 Kb) shows the result of AFM observation at 30 ° C after heat-treating this sample at 142 ° C for 1 hour. It can be seen that there is no change from the molecular orientation state immediately after recording (Fig. 11 (a)). Furthermore, after heat-treating this sample at 148 ° C above its melting point for 1 hour, the results of AFM observation at 30 ° C again are shown in Fig. 11 (c). It can be seen that the orientation of the molecules whose orientation has been controlled is disturbed, and the microcrystals are oriented in different directions. As described above, the area where microcrystals are arranged By cooling the region after raising the temperature to 147 ° C or higher, which is the melting point of the P (VDF-TrFE) film, it was possible to restore the original state in which the microcrystals were not distributed 1J. In other words, the P (VDF-TrFE) film on the graphite substrate can erase the information written in the micro area by this caloric heat, with the c-axis parallel to the film surface and the in-plane directions. It was. As described above, the P (VDF-Tr rFE) film on the glass substrate records the information by moving the recording needle and the c-axis is arranged in the moving direction of the recording needle (direction parallel to the film surface). By heating to a temperature (160 ° C) sufficiently higher than the melting point (147 ° C), the c-axis was aligned perpendicular to the film surface, and the information was erased. Also, by setting the entire P (V DF-TYFE) film to a temperature higher than the melting point, all recorded information could be erased at once.

(2-3) Information recording in which polarization information is superimposed on orientation information (P (VDF-TrFE) film is used as a recording medium) It is known that a P (VDF-TrFE) film has ferroelectricity. First, using the method of Example (2-1), a P (VDF_TrFE) thin film with a thickness of 75 mm was formed on the graphite substrate and heated to 142 ° C, using the method of the above example. The information was recorded by controlling the orientation of the molecules. Next, at 30 ° C, a metal-coated conductive recording needle was brought into contact with the film surface, and a size of 700 nm X 700 nm in this molecular orientation controlled region was applied while applying a voltage of +7 V. Region 53 was scanned and polarized. Further, while applying a voltage of −7 V to the recording needle, the region 54 having a size of 300 nm × 300 nm within the region subjected to the polarization treatment was scanned, and the polarization treatment was performed in the direction opposite to the polarization. Through the series of operations described above, information recording by polarization was performed in superposition with information recording by molecular orientation. Figure 12 (a) shows an AFM image of the area recorded at 30 ° C after the above processing. Thick arrows indicate the direction in which force was applied using the recording needle during the orientation process. In addition, the region subjected to polarization treatment is indicated by a dotted line. From this figure, it can be seen that the molecules are neatly controlled in orientation. Further, FIG. 12 (b) shows the result of measuring the polarization information of the above-mentioned regions 53 and 54 by using the technique of the piezoelectric power microscope. It can be seen that the polarization is clean in the + and – directions. Further, in the above operation, it is understood that the information can be rewritten because the -direction polarization is formed in the region 54 where the polarization information in the + direction has already been recorded. In this way, by using the P (VDF_TYFE) film as the high density information recording medium 10 of the high density information recording apparatus shown in FIG. For The recording of information by the polarization control that was performed could be performed independently. As a result, the recording density could be further increased.

 [0075] (2-4) Example using polyethylene film as recording medium

 After spin-coating a solution of polyethylene in xylene on a graphite substrate

And heat treatment at 165 ° C. As a result, a polyethylene film having a thickness of 200 mm with the c-axis (molecular chain axis) aligned perpendicular to the film surface was obtained (FIG. 13 (a)). While this polyethylene film was heated to 125 ° C, slightly lower than its melting point of 133 ° C, the recording needle was brought into contact with the film surface with a needle thickness of 30 nN. Next, the film was moved in parallel to the film surface at a speed of 10 zm / sec, and a horizontal force was applied to the film surface. The AFM image of the film after this treatment is shown in Fig. 13 (b). Here, the direction in which the force is increased using the recording needle is indicated by an arrow. The microcrystals in the film after the movement of the recording needle are arranged with the c-axis facing this direction of movement. From the above results, it can be seen that the polyethylene film can record information by controlling the molecular orientation in the same way as the P (VDF_TrFE) film.

 [0076] (2-5) Example of using polybutene film for recording medium

 A solution prepared by dissolving polybutene in xylene was spin-coated on a graphite substrate, and then heat-treated at 130 ° C. As a result, a polybutene crystal in which the c-axis (molecular chain axis) was arranged 1J parallel to the film surface was obtained. These crystals are randomly oriented in the film plane (Fig. 14 (a)). While this polybutene film was heated to 112 ° C, which is slightly lower than its melting point of 115 ° C, the recording needle was brought into contact with the surface of the film with a needle thickness of 2 nN and parallel to the film surface at a speed of 20 nanometer / second. A horizontal force was applied to the membrane surface. Figure 14 (b) shows the AFM image of the film after this treatment. Here, the direction in which the force is increased using the recording needle is indicated by an arrow. Due to the force applied using the recording ^ ", the crystallites in the film are aligned so that the c-axis is in this direction of movement. Using this fact, the polybutene film is a P (VDF-TrFE) film. It can be seen that information can be recorded in the same way as with polyethylene film.

 [2-6] Information recording by controlling crystal orientation (P (VDF-TrFE) film as recording medium)

A film was formed in the same manner as in Example (2-1) to obtain a P (VDF-TrFE) thin film with a thickness of 25 mm. With this film heated to 80 ° C., the recording needle is brought into contact with the film surface and moved in the same manner as in Example (2-1) to apply a horizontal force to the film surface to record information. It was. The results are shown in Fig. 15 (a) as an AFM image observed at 30 ° C. The direction of the force applied using the recording needle is indicated by an arrow. Shown in Here, the lower half of the figure is an area where information is recorded. From this figure, as shown in Fig. 15 (b), the crystallites rotate and the major axis of the crystallites changes as shown in Fig. 15 (b). It can be seen that the needles are neatly oriented in the direction of needle movement. As described above, by appropriately selecting conditions such as temperature, material, and the magnitude of force applied by the recording needle, the orientation direction of not only molecules but also microcrystals can be controlled using the method of the present invention. It is possible to record information.

 (3) Embodiment of information reproduction method according to the present invention

 (3-1) Example of information reproduction 1

Information recorded on the information recording medium (Fig. 16 (a)) in which the orientation of the molecules was controlled after P (VDF-TrFE) was produced on the graphite substrate using the same method as in Example (2-1). An example of playing is shown. Here, the lower half of FIG. 16 (a) is the above-described orientation control, that is, an area where information is recorded. After the recording / reproducing needle 13 was brought into contact with the above region, the recording medium was vibrated at a frequency of 10 kHz in the y-axis direction using the fine movement device 12b shown in FIG. In this state, the amplitude of vibration in the y-axis direction (here, the short axis of the panel panel 14 is installed in the y-axis direction) transmitted to the recording / reproducing needle 13 was detected using the detection unit 16 and the lock-in amplifier. Figure 16 (b) shows an image of the above data at each point. In this figure, it can be seen that the detected amplitude output is small (the image is dark) in the area where information is recorded (lower half of the figure). In the area where the information is recorded, the molecular force is oriented in the direction of the molecular chain force axis (the long axis of the crystallites is oriented in the X-axis direction), so the frictional force in the molecular chain direction becomes the frictional force perpendicular to the molecular chain. Therefore, the amplitude output of the vibration transmitted to the recording / reproducing needle 13 in contact with the film surface is small with respect to the vibration in the y-axis direction of the recording medium. On the other hand, in the area where the information is not recorded (upper half of the figure), each microcrystal is oriented in a random direction, so the molecular chain force S _x axis direction of these microcrystals ( The crystallites facing the long axis force (Sy axis direction) of the crystallite are brightly displayed in Fig. 16 (b) where the amplitude output is large. Thus, the presence or absence of orientation can be detected by the difference in amplitude output, and information recorded on the thin film can be read out.

[0079] This method can also be used for other than thin films in which information is recorded depending on the presence or absence of orientation. For example, the major axis direction of the microcrystals is parallel to the y axis (0 ° direction), 45 from the y axis. Three types of information arranged in the rotated direction (45 ° direction) and x-axis direction (90 ° direction) are recorded on the thin film. When recorded, the amplitude output obtained by the above playback method has the minimum value when the orientation is 0 ° (the image is darkest), the maximum value when the orientation is 90 ° (the image is brightest), and the amplitude output when the orientation is 45 °. It becomes the intermediate value. As a result, information of three values or more can be recorded and read in one area, and the recording density can be further increased.

[0080] This method is not limited to P (VDF-TrFE) produced on the above graphite substrate, but also a P (VDF-TrFE) film formed on another substrate such as a glass substrate or a metal substrate, The present invention can also be applied to thin films made of other materials such as polyethylene films and polybutene films.

 [0081] (3-2) Example 2 of information reproduction

 An example is shown in which recorded information is reproduced on an information recording medium in which the orientation of molecules is controlled after a polyethylene film having a thickness of 300 mm is formed on a graphite substrate using the same method as in Example (2-4). . After the recording / reproducing needle 13 is brought into contact with the area where information is recorded, the recording / reproducing needle 13 is vibrated at a frequency of 30 kHz in the y-axis direction by using the vibration mechanism 22 shown in FIG. In this state, the amplitude and phase of vibration in the y-axis direction of the recording / reproducing needle 13 are detected using the detection unit 16 and the lock-in amplifier. By imaging the above data at each point, molecular orientation information can be read as in Example (3-1). By using this method, the same results can be obtained for polyethylene films formed on other substrates such as glass substrates and metal substrates, as well as P (VDF-TrFE) films and polybutene films. Information recorded by control can be read.

 [3-3] Example 3 of information reproduction

An example will be shown in which recorded information is reproduced for a polyethylene film on which information is recorded using the same method as in Example (3-2). First, the recording / reproducing needle 13 is moved closer to the surface of the recording medium using the stage moving mechanism 12 while vibrating in the z-axis direction at 10 kHz using the vibrating mechanism 23. Then, the position of the recording / reproducing needle 13 in the z-axis direction is determined so that the recording / reproducing needle 13 intermittently contacts the surface of the recording medium. Next, using the vibration mechanism 22 shown in FIG. 1, the recording / reproducing needle 13 is vibrated at a frequency of 50 kHz in the y-axis direction. In this state, the amplitude and phase of the vibration in the y-axis direction of the recording / reproducing needle 13 are detected using the detection unit 16 and the lock-in amplifier. By imaging the above data at each point, the orientation information of the molecule can be read as in Example (3-2). By using this method, glass substrate, gold Similar results can be obtained with polyethylene films formed on other substrates such as metal substrates, as well as P (VDF-TrFE) films and polybutene films, and the recorded information can be read by controlling molecular orientation. .

[0083] (3-4) Example 4 of information reproduction

 An example of reproducing recorded information using an information recording medium in which the orientation of molecules is controlled after a polybutene film is formed on a graphite substrate using the same method as in Example (2-5) is shown. The After the recording / reproducing needle 13 is brought into contact with the area where the information is recorded, the recording / reproducing needle 13 is moved in the y-axis direction, which is perpendicular to the long axis of the plate panel 14 that supports the stage moving mechanism 12. Move only a small distance. As a result, the recording / reproducing needle 13 applies a force in the moving direction to the film surface. The magnitude of torsional deformation in the y-axis direction of the leaf spring 14 at this time is detected by the detector 16. Since the deformation of the plate panel is larger in the region where the molecules are oriented in the X-axis direction than in the region where the molecules are oriented in the y-axis direction, the orientation direction of the molecules can be read out. By imaging the above data at each point, molecular orientation information can be read as in Example (3-2). By using this method, similar results can be obtained for polyethylene films formed on other substrates such as glass substrates and metal substrates, as well as P (VDF-TrFE) films and polybutene films, and recording can be performed by controlling molecular orientation. Information can be read

[3-5] Example 5 of information reproduction

After producing P (VDF-TrFE) on a glass substrate using the same method as in Example (2-1), heating to 160 ° C, the molecular chain is formed on the substrate as shown in Fig. 9 (a). An example in which the recorded information is reproduced by a film oriented perpendicularly. After bringing the recording / reproducing needle 13 into contact with the area where the information is recorded, the recording medium (P (VDF-TYFE) film is vibrated in the z direction at a frequency of 10 kHz from the back using the fine movement device 12b shown in FIG. This vibration propagates to the recording / reproducing needle 13 while causing attenuation or phase delay inside the film, and the detection unit 16 detects the amplitude and phase information of the vibration of the recording / reproducing needle 13 in the z-axis direction, and lock-in amplifier. In the region where molecules are aligned in parallel to the region perpendicular to the substrate, vibration attenuation and phase lag are larger in the film than in the region where molecules are aligned perpendicular to the substrate. The force that is oriented in any parallel direction can be detected. By imaging, molecular orientation information can be read. By using this method, the same results can be obtained for polyethylene films formed on other substrates such as glass substrates and metal substrates, as well as P (VDF-TrFE) films and polybutene films. The recorded information can be read out.

[0085] (3-6) Example of information reproduction 6

An example is shown in which recorded information is reproduced for a P (V DF-TYFE) film in which molecular chains obtained by using the same method as in Example (3-5) are oriented perpendicular to the substrate. While the recording / reproducing needle 13 is vibrated in the z-axis direction at 10 kHz using the vibration mechanism 23 shown in FIG. 1, the stage moving mechanism 12 is used to approach the recording medium surface, and the recording / reproducing needle 13 is intermittently moved to the surface of the recording medium. Determine the z-axis position of the recording / playback needle 13 so that In this state, the amplitude and phase information of the vibration in the z-axis direction of the reproduction member is detected using the detection unit 16 and the lock-in amplifier. The direction of the region in which molecules are aligned in parallel to the region aligned perpendicular to the substrate. The elastic modulus in the ¾-axis direction is small and the energy loss on the film surface is large, so the elastic modulus in the _z- axis direction is small and the phase lag is large. Since a signal is obtained, it is possible to detect a force in which a molecular chain is oriented in a direction perpendicular to or parallel to the substrate from these elastic moduli and phase lag. By using this method, similar results were obtained for polyethylene films formed on other substrates such as glass substrates and metal substrates, as well as P (VDF-TrFE) films and polybutene films. The recorded information can be read out.

[0086] (3-7) Example 7 of information reproduction

An example will be shown in which recorded information is reproduced for a polyethylene film on which information is recorded using the same method as in Example (3-2). First, the recording / reproducing needle 13 is moved closer to the surface of the recording medium using the stage moving mechanism 12 while vibrating in the z-axis direction at 10 kHz using the vibrating mechanism 23. Then, the position of the recording / reproducing needle 13 in the z-axis direction is determined so that the recording / reproducing needle 13 intermittently contacts the surface of the recording medium. Next, the recording medium was vibrated at a frequency of 10 kHz in the y-axis direction using the fine movement device 12b shown in FIG. In this state, the amplitude and phase of the vibration in the y-axis direction of the recording / reproducing needle 13 are detected using the detection unit 16 and the lock-in amplifier. By imaging the above data at each point, molecular orientation information can be read as in Example (3-2). By using this method, glass substrate, metal substrate Similar results can be obtained for polyethylene films formed on other substrates such as plates, as well as P (VDF-TrFE) films and polybutene films, and the ability to read the information recorded by molecular orientation control can be achieved.

 [0087] (3-8) Example 8 of information reproduction

 An example of reproducing recorded information using an information recording medium in which the orientation of molecules is controlled after a polybutene film is formed on a graphite substrate using the same method as in Example (2-5) is shown. The First, while the recording / reproducing needle 13 is vibrated in the z-axis direction at 10 kHz using the vibrating mechanism 23, the recording / reproducing needle 13 is moved closer to the recording medium surface using the stage moving mechanism 12. Then, the position of the recording / reproducing needle 13 in the z-axis direction is determined so as to intermittently contact the surface of the recording medium. After the recording / reproducing needle 13 is intermittently brought into contact with the area where the information is recorded, the recording / reproducing needle 13 is moved in the direction perpendicular to the long axis of the plate panel 14 that supports the stage moving mechanism 12 using the y-axis. Move it a small distance in the direction. As a result, the recording / reproducing needle 13 applies a force in the moving direction to the film surface. The magnitude of torsional deformation in the y-axis direction of the leaf spring 14 at this time is detected by the detector 16. Since the deformation of the plate panel is larger in the region in which the molecules are oriented in the X-axis direction than in the region in which the molecules are oriented in the y-axis direction, the orientation direction of the molecules can be read out. By imaging the above data at each point, molecular orientation information can be read as in Example (3-2). By using this method, similar results are obtained for polyethylene films formed on other substrates such as glass substrates and metal substrates, as well as P (VDF-TrFE) films and polybutene films. The recorded information can be read.

 [0088] (3-9) Example 9 of information reproduction

Using the same method as in Example (2-1), in the area of 100 nm × 100 nm in the P (VDF-TrFE) thin film formed on the graphite substrate as the recording medium:! -11 Information was recorded by controlling the orientation of molecules in different directions. Next, using the same method as in Example (3-1), information was reproduced as the torsional amplitude of the panel panel 14. The results are shown in Figure 17. In this figure, the horizontal axis represents the angle between the orientation direction of the molecules in the regions 1 to 11 and the minor axis of the leaf spring 14, and the vertical axis represents the magnitude of the torsional amplitude. In addition, the solid line shows the magnitude of the torsional amplitude due to friction that is theoretically expected based on the values of 0 ° and 90 ° between the numerator and the plate panel. Show. From the results in Fig. 17, it is understood that information recorded using the method of Example (2-1) in all directions within the recording medium surface can be accurately reproduced using the method of Example (3-1). Karu.

 It should be noted that the specific embodiments or examples made in the section of the best mode for carrying out the invention are merely to clarify the technical contents of the present invention, and The present invention is not limited to specific examples and should not be construed in a narrow sense, and can be implemented with various modifications within the scope of the following claims.

Industrial applicability

[0090] As described above, the present invention relates to a high-density information recording, reproducing, and erasing method, and a medium and apparatus used therefor. Therefore, it has a wide range of industrial applicability, including the electronics industry using powerful technology.

Claims

The scope of the claims

 [1] Applying a force in a direction parallel to the film surface to the surface of the thin film using a member having a sharp tip shape on the minute area of the thin film formed on the substrate. An information recording step of recording information by changing the orientation direction of the fine particles, microcrystals or molecules;

 An information reproduction step of reproducing the information recorded by the information recording step, and the information reproduction step,

 A member having a sharp tip shape is contacted with the thin film regularly or intermittently, and the member is moved and / or vibrated by a minute distance in a direction parallel to the film surface with respect to the thin film, and a force generated between the two And a method of reading the orientation direction of the fine particles, microcrystals, or molecules in the minute region by detecting the above.

 [2] A microscopic region of the thin film formed on the substrate is contacted with a temperature-controlled member having a sharp tip shape and the surface of the thin film is controlled to control the microscopic surface temperature. An information recording process for recording information by changing the orientation direction of fine particles, microcrystals or molecules in the region;

 An information reproduction step of reproducing the information recorded by the information recording step, and the information reproduction step,

 A member having a sharp tip shape is contacted with the thin film regularly or intermittently, and the member is moved and / or vibrated by a minute distance in a direction parallel to the film surface with respect to the thin film, and a force generated between the two And a method of reading the orientation direction of the fine particles, microcrystals, or molecules in the minute region by detecting the above.

[3] The high-density information recording / reproducing method according to claim 1 or 2, wherein the information recording step records information of three or more values in one information recording area in a minute area of the thin film. Raw method.

[4] In a state where the member having the sharp tip shape is in contact with the surface of the thin film constantly or intermittently in the information recording step, the distance is moved in a direction parallel to the film surface. 4. The high-density information recording / reproducing method according to claim 1, wherein the information is recorded by vibrating.

[5] Applying a force in a direction parallel to the film surface to the surface of the thin film using a member having a sharp tip shape on the minute area of the thin film formed on the substrate. A high-density information recording method characterized by recording information by changing the orientation direction of fine particles, microcrystals or molecules.

[6] A microscopic region of the thin film formed on the substrate is brought into contact with a member having a sharp tip shape whose temperature is controlled, and the surface of the thin film is controlled to control the microscopic surface temperature. A high-density information recording method characterized by recording information by changing the orientation direction of fine particles, microcrystals or molecules in a region.

7. The high-density information recording method according to claim 5 or 6, wherein information of three or more values is recorded in one information recording area in the minute area of the thin film.

[8] By moving or vibrating the member having the sharp tip shape in a direction parallel to the film surface in a direction parallel to the film surface while being in contact with the surface of the thin film regularly or intermittently.

8. The high-density information recording method according to claim 5, wherein information is recorded.

[9] The high-density information recording method according to [5], [7] or [8], wherein the temperature of the minute region of the thin film is controlled.

10. The high-density information recording method according to any one of claims 5 to 9, wherein a contact pressure in a minute region of the thin film is controlled.

11. The method according to claim 5, wherein different information is recorded by superimposing the information by applying an electric field to the minute region of the thin film and changing polarization in the minute region. The high-density information recording method described in any one of the above.

12. The method according to claim 5, wherein different information is recorded by being superimposed on the information by applying a magnetic field to the minute region of the thin film and changing the magnetization in the minute region. The high-density information recording method described in any one of the above.

[13] An information recording medium having at least a substrate and a thin film laminated on the substrate, wherein information can be recorded on the thin film by the high-density information recording method according to any one of claims 5 to 12. A high-density information recording medium characterized by the above.

14. The high-density information storage device according to claim 13, wherein a plurality of the thin films are laminated. Recording media.

 [15] A method for reproducing information recorded by the high-density information recording method according to any one of claims 5 to 12,

 A member having a sharp tip shape is contacted with the thin film regularly or intermittently, and the member is moved and / or vibrated by a minute distance in a direction parallel to the film surface with respect to the thin film, and a force generated between the two And a method of reading out the orientation direction of the fine particles, microcrystals, or molecules in the minute region by detecting the above.

 [16] A method for erasing information recorded by the high-density information recording method according to any one of claims 5 to 12,

 A high-density information erasing method comprising erasing information using a method similar to at least one of the recording methods according to claim 5.

 [17] A method of erasing information recorded by the high-density information recording method according to any one of claims 5 to 12, wherein the information is recorded by controlling at least a temperature of an information recording area of the thin film. A high-density information erasing method characterized by performing batch erasure.

 [18] Claim: The high-density information recording / reproducing method according to any one of! To 4 and / or the high-density information recording method according to any one of claims 5 to 12 and / or the high-density information according to claim 15. An apparatus for executing the density information reproducing method and / or the high density information erasing method according to claim 16 or 17,

 A member having a sharp tip shape;

 A high-density memory device comprising: a moving mechanism that relatively moves the thin film and the member in the x, y, and z directions.

19. The high-density memory device according to claim 18, further comprising contact pressure control means for controlling a contact pressure between the thin film and the member.

20. The high-density memory device according to claim 18, further comprising vibration control means for vibrating the member and / or the thin film at a predetermined vibration frequency.

21. The high-density memory device according to claim 18, further comprising temperature control means for setting the thin film and / or the member to a predetermined temperature.

22. An electric field applying means for applying an electric field to the thin film is provided. The high density memory device according to any one of 8 to 21.

23. A magnetic field applying means for applying a magnetic field to the thin film is provided.

The high-density memory device according to any one of 8 to 22.

24. The high-density memory device according to claim 18, further comprising means for applying ultrasonic vibration to the thin film.