JP2008282470A - Patterned media manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To fill a magnetic material into the pores of a porous layer efficiently even to the inside of the pores even if a sputtering method is used, the magnetic material layer having very few impurities and high coercive force A method of manufacturing a patterned medium having
A substrate, a porous layer on the substrate and having a plurality of pores substantially perpendicular to the substrate surface, and a magnetic material filled in the pores by a sputtering method are provided. A method for producing a patterned medium, wherein when the magnetic material is filled into a pore by a sputtering method, ion irradiation is performed on the vicinity of the pore to promote migration of sputtered atoms. Patterned media manufacturing method.
[Selection] Figure 8

Description

  The present invention relates to a method for manufacturing a patterned medium that is a perpendicular magnetic recording medium capable of ultra-high density magnetic recording.

  A conventional perpendicular magnetic recording medium mainly comprises a lubricating film, a protective film, a recording layer, a nonmagnetic layer, a soft magnetic backing layer, a nonmagnetic layer, and a substrate. All films are continuous films as shown in FIG. It is. For further high-density recording, it is necessary to refine the magnetic grains forming the magnetic layer in order to ensure a large signal-to-noise ratio (SN ratio). It is not preferable from the viewpoint of thermal fluctuation. As a method of reducing the thermal fluctuation, a method of increasing the medium coercive force can be considered, but the overwrite characteristic tends to deteriorate. Therefore, in recent years, patterned media in which the magnetic material of the recording layer is patterned have been devised. As a result, it is known that a high SN ratio can be secured without increasing the size of the magnetic grains so much that the density can be increased. A form conventionally considered as a patterned medium is a pattern in which a recording layer is patterned on a continuous soft magnetic underlayer as shown in FIG. 2. In such an embodiment, the domain wall of the soft magnetic underlayer is moved. There is a problem that the resulting noise is large and it is difficult to ensure the SN ratio during reproduction. In view of this, a patterned medium in which the soft magnetic underlayer is patterned as shown in FIGS. 3 and 4 has been proposed. By adopting such a form, the movement of the domain wall can be suppressed and noise can be reduced. Further, since the magnetic flux generated from the tip of the main magnetic pole can be effectively passed through the patterned recording layer, a relatively large recording magnetic field can be obtained. Patterned media patterned with such a soft magnetic backing layer uses a imprint technique to create a recess that triggers pattern formation on a substrate such as aluminum or titanium, and then anodizes to form a mold, It is known that it can be obtained by filling the inside with a magnetic material by plating or vapor deposition. In the examples reported so far, the mold is filled with cobalt (Co) by plating, and the coercive force is increased to several thousand Oe by shape magnetic anisotropy. Since the anisotropy is small, it is very difficult to ensure a large squareness ratio.

To perform high-density perpendicular magnetic recording exceeding 1 Tbits / inch ² , the pattern size needs to be about 20 nm or less, and the pattern size needs to be about 10 nm or less in order to cope with higher density. It becomes. It is difficult to form such a micro-sized pattern on the entire surface of the disk, and at present, the production method is limited in terms of production time and cost. At present, the most promising method is to prepare patterned media by filling regularly arranged pores with a diameter of several nm to several tens of nm on the surface of anodized aluminum. For the production of such patterned media, porous alumina is used as a mold.

There exists patent document 1 as a prior art.
Patent Document 1 describes a patterned medium and a manufacturing method thereof. Although it has been described that the inside of the pores of the porous layer is filled with a magnetic material, it has been suggested that it is difficult to fill the magnetic material to the back of the pores using a sputtering method (paragraph 0013). ). Moreover, it does not describe the point of washing the pores before filling the pores with the magnetic material.
JP 2006-277844 A

Various methods are conceivable for filling the magnetic material in the pores of the porous layer, but it is desirable to use a sputtering method in which the crystal orientation is easily controlled. By controlling the crystal orientation, patterned media having a high coercive force can be produced.
In order to perform high-density perpendicular magnetic recording exceeding 1 Tbits / inch ^2, it is necessary to make the pores filled with the magnetic material about 20 nm diameter or less, and about 10 nm or less is necessary for further higher density. Become. On the other hand, in order to fill the recording layer and the soft magnetic backing layer in the pores, it is necessary to make the pores sufficiently deep. It is necessary to fill the pores having a diameter of several to several hundred nm and a depth of several tens of nm to several μm with a magnetic material by sputtering. In a normal semiconductor manufacturing technology, a relatively small one having an aspect ratio (hole depth / hole diameter) of about 3 is filled in by a dry process such as sputtering. However, for those with an aspect ratio of about 10 or higher, hole filling has been attempted by methods such as low pressure long throw sputtering, collimator sputtering, and electric field bias sputtering, but as shown in FIG. Furthermore, since sputtered atoms adhere to the entrance portion at the tip of the hole and close the hole, it is difficult to fill the bottom of the hole with the magnetic material. This is mainly due to the rectilinearity of the sputtered atoms and the weak migration after adhering to the substrate. In general, in low gas pressure sputtering of about 10 ^-1 Pa or less, atoms ejected from the target have fewer collisions with other plasma atoms in the plasma and increase in straightness, but migration after adhesion to the substrate is not very strong. . As a method for promoting the migration of atoms after adhering to the substrate, there is a method of heating the substrate, but it is not efficient from the viewpoint of productivity. In addition, there is a concern about damage to the substrate used due to heat.

  Porous alumina can be obtained by anodizing aluminum. To fill the pores with a magnetic material, it is necessary to clean the pores to remove residual impurities. However, in a generally used cleaning liquid, it is difficult to remove impurities inside the pores because the cleaning liquid does not enter the pores due to the influence of surface tension.

  The present invention solves the above-mentioned problems, and even if a sputtering method is used for filling the magnetic material into the pores of the porous layer, the magnetic material can be efficiently filled to the back of the pores, and there are very few impurities. An object of the present invention is to provide a method for producing a patterned medium having a magnetic layer having a high coercive force.

In order to achieve the above object, the present invention has the following configuration.
A substrate,
A porous layer on the substrate and having a plurality of pores substantially perpendicular to the substrate surface;
A method of manufacturing a patterned medium having a magnetic material filled in the pores by a sputtering method,
A patterned media manufacturing method characterized in that when the magnetic material is filled in the pores by sputtering, ion irradiation is performed on the vicinity of the pores to promote migration of sputtered atoms.

Moreover, it has the following embodiments.
The magnetic body includes two layers, a hard magnetic layer and a soft magnetic layer. The soft magnetic layer is generated below the pores, and the hard magnetic layer is generated above the pores.
Before filling the pores with the magnetic material by sputtering, the inside of the pores is washed with a supercritical fluid.
The porous layer is generated by anodizing the substrate.
The ion energy of the ion irradiation is in the range of 0.1 eV to 10 keV.
The patterned media manufactured by the manufacturing method in any one of the said.

  Since the present invention employs the above-described configuration, even if a sputtering method is used for filling the magnetic material into the pores of the porous layer, the magnetic material can be efficiently filled to the depths of the pores. Fewer magnetic layers can be formed. Since the magnetic material can be filled by sputtering, the crystal orientation can be controlled at the time of filling the magnetic material, and patterned media having a high coercive force can be manufactured. By using the sputtering method and ion irradiation together, the migration of sputtered atoms can be promoted, and even with pores that have multiple magnetic layers and a high aspect ratio, the magnetic material is filled to the back of the pores. Can do. Further, by using a supercritical fluid for cleaning inside the pores, it is possible to effectively clean even inside the pores having a high aspect ratio. If a supercritical fluid obtained by setting the temperature and pressure to a certain value (critical value) or more is used, the inside of a hole having a diameter of several nm can be cleaned. Supercritical fluids have gas properties (diffusivity) and liquid properties (solubility), and can easily enter nano-sized spaces that cannot be penetrated by normal liquids due to surface tension. Effective for precision cleaning of holes and grooves.

  In general, sputtered atoms adhering to the substrate move around on the substrate by migration, and settle to a portion where the energy of the atom itself is the smallest, such as a minute concave portion of the substrate. In other words, in order to fill a porous material such as porous alumina with sputtered atoms, ions having high energy collide with the sputtered atoms adhering to the tip portion of the pores to promote the migration of sputtered atoms. It can be moved to the bottom of the pores. Similar to general sputtered atoms, ions do not fly to the bottom of the pore but only collide near the tip of the pore. Thereby, the tip portion of the pore is always in a high energy state, and the bottom portion of the pore is in a low energy state. By doing so, the sputtered atoms can be moved to the bottom of the pores, and the sputtered atoms can be filled into the pores having a large aspect ratio.

Hereinafter, an example of an embodiment of the present invention will be described.
Porous is produced on the surface of the substrate by anodizing aluminum or titanium, and the soft cleaned or hard magnetic material is filled into the porous cleaned by using a supercritical fluid. Aluminum or titanium can be used for the substrate, and a porous layer can be formed on the surface of the substrate by anodizing this. It is also possible to form aluminum or titanium on a glass substrate and anodize this to produce a porous surface on the substrate. The produced porous material is carried into a washing unit and washed under high temperature and high pressure. Carbon dioxide is used for the supercritical fluid. Since carbon dioxide becomes a supercritical fluid in an environment where the temperature is 31.1 ° C or higher and the pressure is 7.4MPa or higher, the temperature and pressure in the cleaning unit are set to 31.1 ° C or higher and the pressure 7.4MPa or higher to clean the porous material. At this time, if the supercritical fluid is stirred at the same time, it can be effectively washed. Water, methanol, ethanol can be used for the supercritical fluid, and additives can also be added. Table 1 shows the critical temperature and critical pressure of the above-described fluid.

After cleaning the porous material, transport the porous material to the buffer unit, partition the cleaning unit and the buffer unit, reduce the atmospheric pressure to ^10-2 Pa or less with the buffer unit sealed, and partition the buffer unit and the sputter unit. Is opened and the porous material is conveyed to the sputtering unit, and the porous material is filled with a magnetic material by sputtering. There are various sputtering methods, but any method may be used. The magnetic material used for sputtering may be a compound such as oxide and nitride, but is preferably a metal. Ne, Ar, Kr, Xe, etc. can be used as the introduced gas. The substrate is irradiated with ions simultaneously with the sputtering film formation. The energy of the ions to be irradiated may be adjusted to be in the range of about 1 to 300 eV. An ion source using an electron cyclotron resonance phenomenon or an ion source using an inductively coupled plasma is efficient for generating ions, and is effective in promoting the migration of sputtered atoms. When a magnetic material is laminated and filled into a porous material, the top surface of the magnetic material filled in the porous material is not always smooth as shown in FIG. 6, but after the magnetic material is filled, etch back is performed by a dry etching method or the like. As a result, the surface of the magnetic material can be flattened as shown in FIG. At this time, the porous material is also etched by etching, but the porous material is an oxide, so the etching rate is significantly lower than that of the magnetic material, which is a metal, and the deterioration of the porous material due to etching is not big. Thereafter, the recording medium can be produced by filling the porous material with a magnetic material to be a recording layer and performing etching again to smooth the surface. In order to control the crystal orientation of the recording layer, a seed layer having a thickness of several nanometers can be provided between the lower magnetic layer and the recording layer. Further, a diamond-like carbon layer (protective film) and a lubricating film can be formed on the recording layer. A cross-sectional view of the recording medium obtained by such a process is shown in FIG.

  In order to carry out from cleaning to sputtering in a consistent process without exposing the porous material to the atmosphere, a film forming apparatus having at least two or more connected units (chambers) is required. In order to use supercritical fluid for cleaning porous materials, a high-pressure environment is required. On the other hand, a low-pressure environment is required to perform sputtering, so pressure adjustment is required between the cleaning unit and the sputter unit. It is preferable that there is a unit serving as a buffer. The porous material cleaned by the cleaning unit is transferred to the buffer unit without being exposed to the atmosphere, and the pressure is reduced from the high pressure to the low pressure state by the buffer unit, and then transferred to the sputtering unit. By doing in this way, adsorption | suction to the base-material surface, such as water vapor | steam and hydrogen which arises by air | atmosphere exposure, can be prevented, and high quality material preparation is attained.

Although an example of the embodiment of the present invention has been described above, the present invention is not limited to this, and it goes without saying that various modifications can be made within the scope of the technical idea described in the claims. Yes.

Conventional perpendicular magnetic recording media Conventional patterned media Embodiment 1 of patterned media of the present invention Embodiment 2 of patterned media of the present invention Cross-sectional view of pores when magnetic material is filled by conventional sputtering method Cross-sectional view of pore when ion irradiation is performed simultaneously with sputtering Cross-sectional view of pores when etched back after sputtering Sectional drawing of the patterned media manufactured with the manufacturing method of this invention

Claims (6)

A substrate,
A porous layer on the substrate and having a plurality of pores substantially perpendicular to the substrate surface;
A method of manufacturing a patterned medium having a magnetic material filled in the pores by a sputtering method,
A patterned media manufacturing method characterized in that when the magnetic material is filled in the pores by sputtering, ion irradiation is performed on the vicinity of the pores to promote migration of sputtered atoms.   2. The magnetic body includes two layers, a hard magnetic layer and a soft magnetic layer, wherein the soft magnetic layer is generated below the pores and the hard magnetic layer is formed above the pores. Patterned media manufacturing method.   The patterned media manufacturing method according to claim 1, wherein the pores are cleaned with a supercritical fluid before filling the pores with at least the magnetic material.   The patterned media manufacturing method according to claim 3, wherein the process from supercritical fluid cleaning to magnetic material filling is performed in a consistent process in an enclosed space without exposure to the atmosphere.   The patterned medium manufacturing method according to claim 1, wherein the porous layer is generated by anodizing the substrate. A patterned medium manufactured by the manufacturing method according to claim 1.

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