Patent Application
20080050616
The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which:
Hereinafter, a method of manufacturing a magnetic layer, a patterned magnetic recording medium including thus formed magnetic layers, and a method of manufacturing the patterned magnetic recording medium according to embodiments of the present invention will be described in detail with reference to the attached drawings. The method of forming the magnetic layer will be described together with the method of manufacturing the magnetic recording medium.
In the drawings, the widths and thicknesses of layers and regions are exaggerated for clarity. Like reference numerals in the drawings denote like elements, and thus their description will be omitted.
The seed layers 350a are formed onto bottoms of the holes H, i.e., on the parts (“exposed parts”) of the interlayer 320, which are exposed through the holes H. The seed layers 350a may be formed using an electroless plating method. The seed layers 350a may be magnetic layers formed of CoP, CoB, NiP, or NiB or nonmagnetic layers formed of Cu, Ag, Au, Ni, or Pd. The seed layers 350a may have a thickness between 1 nm and 30 nm. The seed layers 350 may have a HCP (002) or FCC (111) orientation in the direction parallel to an upper surface of substrate 300. In one exemplary embodiment, the seed layers 350a are nonmagnetic layers, and the interlayer 320 is omitted. In this case, the lower layer 330 may include the soft magnetic layer 310 only. The magnetic layers 350b are formed on the seed layers 350a so as to fill up the holes H. The top surfaces of the magnetic layers 350b locate at the same planar surface regardless of the location of the holes on the magnetic layers 350b. The magnetic layers 350b are formed using an electroplating method. The magnetic layers 350b may be magnetic layers formed of CoNiP, CoPt, CoPtP, CoPtB, CoCrPt, CoCrTa, or CoCrNb. The magnetic layers 350b may be formed of CoPt or FePt, which has a body centered tetragonal (BCT) structure, for example, LiO structure. The magnetic layers 350b may be a multilayer formed of Co/Pt or Co/Pd. The magnetic layers 350b may have a thickness between 10 nm and 100 nm. The magnetic layers 350b have an HCP structure and planes which are parallel with the upper surface of the substrate 300 and <002>-orientated-, thereby the magnetic layers 350b show perpendicular magnetization anisotropic properties. Magnetic anisotropic energy of the magnetic layers 350b is greater than that of the seed layers 350a.
To improve bonding between the substrate 300 and the lower layer 330, the magnetic recording medium may include an additional seed layer (not shown). The seed layer for adhesion may be formed of Ta, Cr, or Ti using a deposition method, e.g., a sputtering method. The seed layer for adhesion may have a thickness between 5 nm and 20 nm.
Referring to
Referring to
The nanoimprinting refers to a nano patterning method which includes manufacturing a master stamp using one of the above-mentioned lithographies, coating a resin layer such as a photoresist layer on the lower layer 330, imprinting the resin layer using the master stamp, and patterning the resin layer on a nano scale.
The nanoimprinting is simple and economical and thus appropriate for mass-productions. However, if the plurality of holes H are formed using the nanoimprinting, portions of the resin layer may remain on bottoms of the plurality of holes H. The portions of the resin layer left on the bottoms of the plurality of holes may be removed using reactive ion etching (RIE) or plasma ashing.
Referring to
An electrolyte used in the electroless plating method may contain salts of a metal, which is to be plated and a reductant. It may further contain auxiliary components including a pH regulator, a buffer, a complexing agent, etc. For example, when the electroless plating method is used to form an Ni seed layer, the electrolyte may contain NiCl2 or NiSO4 as metallic salts, and NaH2PO2, NaBH4, or Hydrazine:N2H4 as a reductant.
The electroless plating renders a formation of a metal plate on the lower layer 330 through a chemical reaction between the electrolyte contained in the electroless plating composition and the lower layer 330 which is formed on a substrate 300, without applying an external current to the substrate 300. Therefore, a resulted plate, that is, the seed layers 350a in one exemplary embodiment as shown in
An uniform seed layers 350a may be obtained using the electroless plating method, even when the portions of the resin layer remain on the bottoms of the holes H. Thus, if the seed layers 350a are formed using the electroless plating method, a step of removing the remaining portions of the resin layer using RIE or plasma ashing may be omitted.
To accelerate the electroless plating, a catalytic nucleus may be formed on an entire upper surface of the lower layer 330, after the lower layer 330 may be formed and before the resin layer 340 is formed. When the lower layer 330 includes a soft magnetic layer 310 and an interlayer 320, the catalytic nucleus may be formed on the upper surface of the interlayer 320. The catalytic nucleus may be formed of a noble metal such as Pd. Alternatively, the catalytic nucleus may be formed after a template 340 is formed on the interlayer 320 but before forming the seed layer 350a. In this case, the catalytic nucleus is formed on parts (exposed parts) of the interlayer 320, where the surface of the interlayer 320 is exposed through the holes H.
Referring to
A planarizing process, e.g., a chemical mechanical polishing (CMP) or burnishing, may be performed to planarize surfaces of the resulting patterned magnetic layers 350b. An anti-corrosion protection layer (not shown) may be on the template 340a and the magnetic layers 350b, followed by coating with a lubricant. The anti-corrosion protection layer may be formed of, for example, diamond-like carbon (DLC).
As described above, in the present invention, the patterned magnetic layers 350b are formed on the seed layers 350a to have an uniform thickness. Thus, the uniformity of thicknesses and micro structures of the patterned magnetic layers 350b may be improved.
Also, before the magnetic layers 350b are formed, the seed layers 350a may be formed using the electroless plating method. This allows a formation of uniform seed layers 350 in each individual hole H. Thus, the total heights of the seed layers 350a and the magnetic layers 350b, which fill up the respective individual holes H, are uniform regardless where the holes H are located on the substrate 300.
In addition, the magnetic layers 350b have the HCP structure and are formed to have planes which are parallel with the upper surface plane of the substrate 300 and <200>-orientated. As a result, the orientation characteristics of the magnetic layers 350b, which are used as data recording layers, are improved, and thus the perpendicular magnetic anisotropic properties and magnetization reverse properties of the patterned magnetic layers 350b may be improved. Moreover, the patterned magnetic layers 350b, which are formed while an external magnetic field M is applied in a direction perpendicular to the upper surface of the substrate 300, have improved orientation properties and magnetic properties.
To improve reading and writing characteristics and a recording density of a magnetic recording medium, magnetization orientation of magnetic domains may be reversed by a coherent rotation. For this purpose, the magnetic layers 350b corresponding to bit sizes may have the HCP structure and (002) planes which are parallel with the upper surface of the substrate 300. Also, the magnetic layers 350b are required to have appropriate thicknesses, aspect ratios and uniform micro structures.
The patterned magnetic layers 350b of the present invention may satisfy the above conditions. Thus, a magnetic recording medium including the magnetic layers 350b according to the present invention may have good reading and writing characteristics and a high recording density of 1 Tb/in2 or higher.
In addition, uniform seed layers 350a may be formed using an electroless plating method, even when portions of the resin layer 340 remain on the bottoms (i.e., exposed parts 360) of the holes H after the nanoimprinting process to form a template 340a, leaving an uneven bottom surface. Therefore, an additional process of removing the portions of the resin layer left on the bottoms of the holes H is not required. As a result, the process may be shortened and simplified.
While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2006-0079470 | Aug 2006 | KR | national |
