KR20020044312A - Data storage device and method of producing magnetic recording media used it - Google Patents

Abstract

PURPOSE: Data storage media are provided to use carbon nanotubes for reducing interferences between neighboring magnetic substances, generated as bit size of magnetic media is smaller and nearer, thereby increasing data stability. CONSTITUTION: A porous material(120) is accumulated on a substrate(110). A ferromagnetic material(140) is contained in porous parts of the porous material, and causes a magnetic polarization phenomenon, to perform magnetic recording media functions. An information recorder applies a magnetic field to the ferromagnetic material, to generate magnetic polarization in the ferromagnetic material, and records information. An information reader extracts an effect of the magnetic polarization of the ferromagnetic material, and reads out an information state in accordance with a polarization direction.

Description

Information storage device and method for manufacturing information storage medium used therein {Data storage device and method of producing magnetic recording media used it}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to data storage media, and more particularly to a vertical magnetic recording medium having a data size of nanometers.

With the advancement of information, high-capacity and high-speed information storage devices are rapidly progressing, and the demand for high-speed and high-density information storage devices capable of recording / reproducing is increasing. In general, an information storage device is divided into a main memory device such as a memory using a semiconductor and an auxiliary storage device such as a hard disk, a CD-ROM, or a CD-RW. In particular, since a hard disk can record and reproduce a large amount of information quickly, it is widely used as an auxiliary storage device of the current computer.

The amount of data that can be recorded per unit area of a hard disk using the current planar magnetic recording medium, that is, the surface recording density is about tens of Gbit / in ² , and is increasing by about 60% every year. This is due to the development of giant magnetoresistence heads rather than the development of magnetic recording media. In magnetic recording, data bits, i.e., zero or one, are recorded in two magnetic moment directions by the direction of the magnetic field of the head flying over the magnetic medium. The regeneration of the magnetic storage device is read out through the current detected by the induced current of the head according to the magnetic moment direction of the recorded bit.

Since the magnetic recording medium uses ferromagneticity due to the long-range ordering of the spins of the electrons of the material, the thermal instability of the magnetic recording medium is inevitably increased as the recording density increases. You will be faced with a Superparamagnetic Limit. If the domain volume of the magnetic medium becomes smaller than the Superdiamagnetic Limit, it is reported that the thin film type magnetic recording medium cannot have a recording density of about 100 Gbit / in ² or more because spontaneous magnetic moment disappears due to thermal energy. have.

Efforts are currently being made to develop a vertical magnetic recording medium to overcome the limitations of the horizontal recording method, but there are no specific research results.

Disclosure of Invention The present invention has been made to solve the above problems, and an object of the present invention is to provide a structure and a manufacturing method of a nanometer-sized stable vertical magnetic recording medium, and to provide an information storage device having high integration and large capacity.

1 is a schematic block diagram of a vertical magnetic recording medium implemented with a ferromagnetic material supported on a nanometer-sized pore in accordance with an embodiment of the present invention.

FIG. 2A is a simplified block diagram of a vertical magnetic recording medium implemented with carbon nanotubes grown in nanometer-sized pores and a ferromagnetic material supported on the carbon nanotubes according to an embodiment of the present invention.

FIG. 2B is an enlarged view of the ferromagnetic material supported in the carbon nanotubes shown in FIG. 2A;

3 is a diagram conceptually illustrating a distribution of bit cells in a magnetic recording medium according to an embodiment of the present invention;

4A to 4H illustrate a process for implementing a nanometer-sized vertical magnetic recording medium according to an embodiment of the present invention.

※ Explanation of code about main part of drawing ※

110: substrate

120: porous materials

130: Carbon Nanotubes

140: ferromagnetic materials supported in the porous

150: protective layer

121: Pore of Porous Materials

131: Graphite Layer

In order to achieve the above object, the present invention provides an information storage device, comprising: a porous material stacked on a substrate; A ferromagnetic material supported in the pores of the porous material and causing a magnetic polarization phenomenon to perform a magnetic recording medium function; Information recording means for recording information by generating magnetic polarization in the ferromagnetic material by applying a magnetic field to the ferromagnetic material; And information reading means for detecting an effect due to magnetic polarization of the ferromagnetic material and reading the information state along the polarization direction.

In addition, the first step of depositing a thin film for making a porous material (Subrous material) on a substrate (Substrate); A second step of forming pores in the thin film by an electrochemical method; A third step of growing carbon nanotubes in the pores formed in the second step; And a fourth step of supporting a ferromagnetic material that performs a magnetic recording medium function by causing magnetic polarization in the carbon nanotubes grown in the third step. Is provided.

By adopting the vertical magnetic recording method, the present invention can significantly increase the recording density than the conventional thin film magnetic recording medium, and ideally provides a few Tbit / in class ² magnetic recording medium. That is, the nano-structured magnetic recording medium of the present invention forms a stable nanometer-sized bit cell without departing from the superparamagnetic limit, and is applied to a magnetic field applied from an external magnetic head. By recording the information by using the polarization reversal of the ferromagnetic material, and detecting the change in the current of the head induced by the interaction with the recorded magnetic polarization, it can be used in the magnetic recording device for reading the recorded information.

In the magnetic recording medium of the present invention, a porous material having a constant array of nanometers is preferably electrochemically anodized porous alumina (Al ₂ O ₃ ) or porous silicon. As the magnetic material, any ferromagnetic metal such as Fe, Ni, Co, alloys thereof, or oxide-based ferromagnetic materials can be used. The pore size of electrochemically anodized porous alumina (Al ₂ O ₃ ) or porous silicon (Porous Silicon) can be adjusted to several to several tens of nanometers by anodizing conditions. In particular, in order to reduce the interference caused by the interaction between neighboring ferromagnetic materials located at several to several tens of nanometers, carbon nanotubes are first grown in the porous material of porous materials, and then a technique of supporting the magnetic material inside the nanotubes is used. It is also possible to use. In order to support the magnetic material in the pores of the porous material of several tens to several tens of nanometers, it is preferable to apply a process capable of manufacturing a high quality nano thin film such as atomic layer deposition (Atomic Layer Deposition).

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a schematic block diagram of a vertical magnetic recording medium embodied by a ferromagnetic material supported on a nanometer-sized pore in accordance with an embodiment of the present invention.

As shown in the figure, the vertical magnetic recording medium embodied by the ferromagnetic material supported in the pore of the present invention is composed of a porous material 120 on the substrate 110, and a ferromagnetic material 140, which is an information storage medium. In some cases, when the medium is operated in an oxidizing atmosphere, a protective layer 15 to prevent oxidation may be required.

FIG. 2A is a simplified block diagram of a vertical magnetic recording medium implemented with carbon nanotubes grown in nanometer-sized pores and a ferromagnetic material supported on the carbon nanotubes according to an embodiment of the present invention, and FIG. It is an enlarged view of the ferromagnetic material supported in the carbon nanotube shown in 2a.

As shown in the figure, a vertical magnetic recording medium made of a ferromagnetic material supported in carbon nanotubes according to the present invention is grown on the porous material 120 and the porous material 120 on the substrate 110. Single-walled or multi-walled carbon nanotubes 130 and a ferromagnetic material 140 that is an information storage medium carried in the carbon nanotubes 130.

Since the carbon nanotubes 130 have metallic properties, the carbon nanotubes 130 reduce the influence of magnetic fields between neighboring magnetic bodies, thereby increasing the stability of data. In addition, since it prevents external chemical substances and improves thermal conductivity, it also serves to prevent deterioration of the magnetic body due to repeated magnetic inversion. The protective film 150 may be applied as necessary as in FIG. 1.

The ferromagnetic medium 140 is divided into a bit cell having a pre-formed pore size. Each ferromagnetic material has a 0 or 1 state according to magnetic polarization generated by an externally applied magnetic field, and is separated into a porous film. The polarization direction is constant only inside the bit cell.

The ferromagnetic material changes the spin state of the internal atoms constituting the ferromagnetic material according to the direction of the magnetic field applied from the outside to generate polarization having a specific direction, and the collection of magnetic polarizations aligned in the same direction is immediately recorded information. . For this purpose, as recording means, a micro-electrode magnetic head (not shown) is placed on top of the medium so that polarization is induced locally only in one bit cell when information is recorded bit by bit. Add. The polarization inside the bit cell is maintained for a long time unless an external magnetic field above the coercive field is applied.

By applying a magnetic field to such ferromagnetic material to generate magnetic polarization, information can be recorded, which can use information recording means such as a conventional head. In addition, if desired information has already been recorded on the ferromagnetic material, the information state can be read by detecting the effect of such magnetic polarization by using information reading means such as a conventional head.

3 is a diagram conceptually illustrating a distribution of bit cells in a magnetic recording medium according to an embodiment of the present invention, in which the above figure shows a disc-shaped magnetic recording medium, and the figure below shows a rectangular portion of the figure. Shows the shape of the bit cell when viewed from above.

In general, when a porous material is formed, it spontaneously has a hexagonal structure or a cubical structure, and the hexagonal structure has a higher recording density. The bit cell of the present invention may have a size of several tens to several tens of nanometers, and the exact size may be controlled by the conditions for forming the porous material.

4A to 4H illustrate a process for implementing a nanometer-sized vertical magnetic recording medium according to an embodiment of the present invention, which will be described in detail as follows.

4A is a cross-sectional view after depositing a thin film 120 for making a porous material on the substrate 110. The thin film 120 for making the porous material is deposited as a thin film using conventional physical vapor deposition or chemical vapor deposition, and the material is porous alumina (Porous Alumina, Al ₂ O ₃ ) or porous silicon (Porous Silicon), etc. It is preferable to use.

4B is a cross-sectional view when the porous layer 121 is formed of the substrate 110 and the thin film 120 for making a porous material by an electrochemical method. As mentioned above, the size of the pores can range from several tens to tens of nanometers, and the exact size can be controlled by the conditions for forming the porous material.

4C is a cross-sectional view of the substrate 110 and the porous material 120 after supporting the magnetic material. Since the size of the pores is several tens to several tens of nanometers, the uniform magnetic material cannot be supported in the pores by conventional physical vapor deposition or chemical vapor deposition. Therefore, it is recommended to use the atomic layer deposition method having excellent nanometer-sized stack coverage. desirable. In addition, in the case of the porous material 120 and the ferromagnetic material having a large surface tension, the porous material 120 may be formed into a molten solution and supported by capillary action.

Figure 4d shows a process for making a magnetic material supported on the carbon nanotubes shown in Figures 2a and 2b. The cross-sectional view after growing the carbon nanotubes 130 in the pores 121 of the substrate 110 and the porous material 120. The carbon nanotubes 130 may grow molecules or polymers containing carbon by chemical vapor deposition (CVD) or thermal decomposition. A single or multi-ply carbon nanotubes may be formed according to the pore size. Is generated. In addition, when alumina or the like is used as the porous material, the graphite layer 131 may be formed above the pores, which may be etched in an oxidizing atmosphere.

FIG. 4E is a cross-sectional view of the carbon nanotube having an open end by etching the graphite layer 131 above the pore in FIG. 4D. Etching may be performed by heating at 700 ° C. or above in an oxygen atmosphere or dissolving in nitric acid.

FIG. 4F is a cross-sectional view when the magnetic material is supported in the open carbon nanotube produced in FIG. 4E. FIG. It is preferable to use the above-mentioned atomic layer deposition method or the capillary phenomenon of a molten solution for the method of carrying a magnetic substance. After supporting the magnetic material, it is necessary to close the tip of the carbon nanotube as necessary, which can be achieved by heat treatment at 400 ℃ or laser beam irradiation.

4G and 4H are sectional views when the protective layer 150 is applied to the magnetic recording medium formed in FIGS. 4C and 4F, respectively. Conventional hard disks do not require a protective layer because the media is contained in a vacuum packaged box, but in the case of a detachable disk, application of a polymer film or the like to prevent oxidation of the media may be required.

The present invention described above is capable of various substitutions, modifications, and changes without departing from the spirit of the present invention for those skilled in the art to which the present invention pertains, and the above-described embodiments and accompanying It is not limited to the drawing.

According to the present invention as described above, it has been proposed a method of dramatically increasing the recording density of magnetic recording by providing a nanometer-sized vertical magnetic recording medium. In addition, as a material for reducing the interference between neighboring magnetic material generated as the bit size of the magnetic medium becomes smaller and closer, there is an effect of providing a medium that can improve the stability of data using carbon nanotubes.

Claims (14)

In the information storage device, A porous material stacked on a substrate; A ferromagnetic material supported in the pores of the porous material and causing a magnetic polarization phenomenon to perform a magnetic recording medium function; Information recording means for recording information by generating magnetic polarization in the ferromagnetic material by applying a magnetic field to the ferromagnetic material; And And information reading means for detecting an effect due to magnetic polarization of the ferromagnetic material and reading the information state along the polarization direction. The method of claim 1, The ferromagnetic material, The information storage device, characterized in that produced by using any one of atomic layer deposition or capillary phenomenon of the molten solution in order to support in the porous. The method of claim 1, The ferromagnetic material is stored in nanometer-sized carbon nanotubes (Carbon Nanotubes), characterized in that formed in the pores of the porous material. The method of claim 3, wherein The ferromagnetic material, In order to support the carbon nanotubes, the information storage device, characterized in that produced using any one of atomic layer deposition or capillary phenomenon of the molten solution. The method of claim 1, An porous material for supporting the ferromagnetic material, information storage device, characterized in that manufactured using any one of porous alumina (Porous Alumina) or porous silicon (Porous Silicon). The method of claim 1, And a protective layer laminated on the surface of the ferromagnetic material to prevent oxidation when the ferromagnetic material is operated in an oxidizing atmosphere. Depositing a thin film to form a porous material on a substrate; A second step of forming pores in the thin film by an electrochemical method; A third step of growing carbon nanotubes in the pores formed in the second step; And a fourth step of supporting a ferromagnetic material that performs a magnetic recording medium function by causing magnetic polarization in the carbon nanotubes grown in the third step. The method of claim 7, wherein The thin film for making the porous material is an information storage medium manufacturing method using a carbon nanotube, characterized in that formed using any one of porous alumina (Porous Alumina, Al ₂ O ₃ ) or porous silicon (Porous Silicon). The method of claim 7, wherein The third step, The carbon nanotube is a method of manufacturing an information storage medium using carbon nanotubes, characterized in that the growth of the molecule containing carbon using any one of chemical vapor deposition (CVD) or pyrolysis method. The method of claim 7, wherein The fourth step, Method for manufacturing information storage medium using carbon nanotubes, characterized in that by using the atomic layer deposition method to support the ferromagnetic material in the carbon nanotubes. The method of claim 7, wherein The fourth step, In order to support the ferromagnetic material in the carbon nanotubes to form the ferromagnetic material in the form of a molten solution to carry the information storage medium using carbon nanotubes, characterized in that the capillary phenomenon. The method of claim 7, wherein When the carbon nanotubes are grown, if graphite is formed on the pores, the method of manufacturing the information storage medium using the carbon nanotubes further comprises etching the graphite. The method of claim 12, When the carbon nanotube ends are opened by etching the graphite, the carbon nanotubes may be closed by using one or more of a heat treatment method or a laser beam irradiation method. Information storage medium manufacturing method used. The method of claim 7, wherein And forming a protective layer on the surface of the ferromagnetic material in order to prevent oxidation of the ferromagnetic material.