Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
2001-08-03
2004-03-23
Heinz, A. J. (Department: 2653)
Dynamic magnetic information storage or retrieval
Head
Core
Reexamination Certificate
active
06710973
ABSTRACT:
PRIORITY TO FOREIGN APPLICATIONS
This application claims priority to Japanese Patent Application No. P2000-286842 and P2000-328405.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention concerns a thin layer magnetic head used for recording and reproduction, for example, in a magnetic disk storage apparatus and a magnetic disk storage apparatus mounting the magnetic head.
2. Description of the Background
In a magnetic disk storage apparatus, data on the recording media is read and written by a magnetic head. In order to increase the recording capacity per unit area of the magnetic disk, it is necessary to increase the area recording density. However, the area recording density of existing in-plane recording systems can not be increased as the length of bits to be recorded is decreased because of thermal fluctuation in the magnetization of the media.
A perpendicular recording system which records magnetization signals in a direction perpendicular to a medium is adapted to address this problem. In the perpendicular recording system, a magnetoresistive head (“MR head”) and a giant magnetoresistive head (“GMR head”) with a larger read output than non-perpendicular systems can be used for reading. However, a single pole head must to be used for the writing head in these systems. With perpendicular recording, it may be necessary to improve the track density and the linear recording density in order to improve the recording density. To improve the track density, the track width of the magnetic head is decreased and formed with higher accuracy.
In a perpendicular recording system, the shape of the main pole of the single pole type recording head has a significant effect on the magnetization pattern of the media. Specifically, the shape of the upper end face of the main pole, which is the end face of the main pole on the side opposite to the MR head (on the trailing side), greatly affects the shape of the magnetization pattern of the media. For example, JP-10-320720/1998 discloses the structure of a single pole type head having a main pole of a trapezoidal shape flattened at the upper end face and wider on the side of the MR head.
However, in the description in JP-10-320720/1998, a description is made of side recording tracks defined by the slope on both sides of the trapezoidal shape. These side recording tracks reduce cross talk with adjacent recording tracks, however, they hinder the improvement of the track density which therefore hinders any improvement in the area recording density. In such a magnetic disk storage apparatus, a skew angle is formed when the magnetic head scans from the inner circumference to the outer circumference of a disk, in which the trapezoidal pole shape erases signals on adjacent tracks. JP-10-320720/1998 has no specific descriptions about the pole forming method.
By using a polishing method, the upper surface of the main pole (second pole) can be flattened. However, when a polishing method such as chemical mechanical polishing (CMP) is used, it is difficult to control the layer thickness which hinders the accuracy of the layer thickness. The thickness may vary by as much as about ±0.5 &mgr;m. This inaccuracy scatters the layer thickness of the main pole, thereby causing scattering in the intensity of the magnetic field from the main pole. Accordingly, it is preferred to adopt a flattening method for the upper surface of the main pole having improved controllability (accuracy) for the layer thickness.
In view of the above, the present invention preferably provides a magnetic head for perpendicular recording having a main pole of a shape with no side recording which does not erase signals on adjacent tracks caused by a skew angle. The invention also includes a manufacturing method of the magnetic head and a magnetic disk storage apparatus mounting the magnetic head for perpendicular recording.
SUMMARY OF THE INVENTION
A single pole type recording head for perpendicular recording in accordance with at least one preferred embodiment of the present invention comprises a first pole (auxiliary pole), a second pole (main pole) and a gap layer formed between the first and second poles in which the width of the first pole opposed to the gap layer is larger than the width of the second pole opposed to the gap layer. When defining the surface of the second pole opposed to the gap layer as a “lower layer” and the surface of the second pole on the side opposite the lower surface (that is, on the trailing side) as an “upper surface” which is flat, the width (B) of the lower surface is preferably smaller than the width (A) of the upper surface in the second pole. Further, an angle formed between the upper surface and both lateral (side) surfaces of the second pole is an acute angle. In accordance with this invention, a magnetic disk storage apparatus is formed by mounting the magnetic head.
In at least one preferred embodiment, the second pole has a shape in which the size changes continuously (i.e., linearly) from the width for the upper surface to the width for the lower surface of the second pole, and each lateral side of the second pole is desirably formed as a slope. In a preferred embodiment, the angle formed between the upper surface and both lateral sides to the upper surface of the second pole is within a range of approximately 60° to 90°. Further, the upper surface of the second pole may be characterized with a “flatness” that varies by less than about 30 nm between the end and the central portion in the upper surface.
In accordance with this invention, a second pole (main pole) is preferably formed by a process characterized by the following sequential steps: forming a resist pattern on an inorganic insulating layer; etching the inorganic insulating layer using the resist pattern as a mask thereby forming a groove having a bottom surface larger than the upper surface and having a slope portion; removing the resist pattern; forming a magnetic layer on the inorganic insulating layer including the groove; and flattening the magnetic layer. The second pole (main pole) may also be formed by a method, following the step of removing the resist pattern, including the sequential steps of: forming a stopper layer for chemical mechanical polishing (CMP) on the inorganic insulating layer; forming a plated underlayer on the stopper layer; plating a magnetic layer on the plated underlayer; and polishing the magnetic layer by chemical mechanical polishing (CMP).
Alternatively, the second pole (main pole) may also be formed by a method, following the step of removing the resist pattern, including the sequential steps of: forming an etching stopper layer on the inorganic insulating layer; forming a plated underlayer on the stopper layer; plating a magnetic layer on the plated underlayer; and flattening the magnetic layer by etching using plasmas.
The inorganic insulating layer is preferably a single layer comprising Al
2
O
3
, AlN, SiC, Ta
2
O
5
, TiC, TiO
2
or SiO
2
, or a laminate or mixed layer comprising two or more of the compounds described above. The magnetic layer constituting the second pole is preferably made of a material having a saturation magnetic flux density (Bs) of at least 1.5 tesla (T). The stopper layer for chemical mechanical polishing (CMP) may be a single layer comprising C, Ta, Mo, Nb, W or Cr, or a laminate layer or an alloy layer comprising the elements described above. The etching stopper layer may be a single layer comprising Cr, Ni, Au, Pt, Pd, Ru, Rh, Cu, Ag, Tc, Re, Os or Ir or a laminate layer or an alloy layer comprising the elements described above.
In order to cope with a narrowed track of the recording head, the width (A) for the upper surface of the second pole (main pole) is preferably 0.3 &mgr;m or less.
In the present invention, the second pole (main pole) of the magnetic head for perpendicular recording has a structure shape that can preferably prevent writing to and erasing adjacent tracks caused by the skew angle in the lateral sides of the second pole. Initially, for preventing writing from the lateral side of
Kawato Yoshiaki
Mochizuki Masafumi
Nishida Yasutaka
Okada Tomohiro
Takano Hisashi
A. Marquez, Esq. Juan Carlos
Fisher Esq. Stanley P.
Heinz A. J.
Reed Smith LLP
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