Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
2000-10-02
2004-02-03
Evans, Jefferson (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Core
C360S317000, C029S603140
Reexamination Certificate
active
06687082
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a magnetic head for a magnetic recording and reproducing apparatus and a manufacturing method of the magnetic head, and a magnetic recording and reproducing apparatus using this magnetic head.
DESCRIPTION OF THE RELATED ART
Because a magnetic recording and reproducing apparatus has been small sized and has had a large capacity, the volume per one bit recorded on a magnetic recording medium has become rapidly small. In order to detect a magnetic signal generated from this small volume of one bit as a large reproducing output, a magnetoresistive (MR) head has been developed. This MR head is described in a technical report written by R. P. Hunt, “A Magnetoresistive Readout Transducer,” IEEE Trans. Mag., MAG-7, No. 1, 1971, pp. 150-154.
Further, a giant MR (GMR) head used a GMR effect, which can realize a largely higher output compared with the MR head, has been put to practical use. In this GMR effect, especially, the change of resistance corresponds to a cosine between the magnetizing directions of two adjacent magnetic layers. At an MR effect called a spin-valve effect, a large change of resistance is generated in a small operating magnetic field, therefore, the GMR head using this spin-valve effect has been largely used. This GMR head using the spin-valve effect is described in a technical report written by C. Tsang et al., “Design, Fabrication & Testing of Spin-Valve Read Heads for High Density Recording,” IEEE Trans. Mag., Vol. 30, No. 6, 1994, pp. 3801-3806. In this technical report, one of two magnetic layers generating the spin-valve effect is a ferromagnetic pinned layer in which magnetization is fixed so that the direction of the magnetism substantially becomes the direction of the magnetic field of a magnetic recording medium that enters to a magnetic sensing part of the head, by an exchange magnetic field generated by layering an antiferromagnetic film on this one of the magnetic layers. And the other magnetic layer, which contacts with the ferromagnetic pinned layer via a conductive layer such as Cu, is a ferromagnetic free layer whose direction of the magnetism can be changed freely for the magnetic field of the magnetic recording medium. Hereinafter, this GMR head using the spin-valve effect is called a GMR head.
FIG. 1
is a diagram showing a structure of a conventional GMR head seen from an air-bearing surface (ABS) being a surface facing a magnetic recording medium.
FIG. 2
is a sectional view of the conventional GMR head at the line AB in FIG.
1
. As shown in
FIGS. 1 and 2
, at the conventional GMR head, a magnetism separating layer
3
made of an insulation material is formed between an upper shield
6
and a lower shield
2
layered on a ceramic
1
becoming a slider, and a spin-valve layered structure generating the GMR effect as a central region
4
is disposed in this magnetism separating layer
3
. End regions
5
, which supply current and a bias magnetic field to this central region
4
, are formed at both ends of this central region
4
. The part mentioned above is a GMR element for reproducing.
Further, the upper shield
6
is made to be a first magnetic core
6
, and on the opposite side surface of the first magnetic core
6
existing the GMR element, a second magnetic core
11
is layered in parallel with the first magnetic core
6
via a recording gap
7
. At the part between the first and second magnetic cores
6
and
11
, a coil
9
, which is covered with a non magnetizing insulator
8
and a non magnetizing insulator
10
, is disposed. Recording is executed by using a magnetic flux generated from the recording gap
7
between the first and second magnetic cores
6
and
11
magnetized by a magnetic field generated by the coil
9
. A structure, in which a reproducing head by the GMR element and a recording head by an inductive (ID) head are layered, is a practical GMR head.
The GMR head is actually used at a region in which the recording density is more than 3 G bits per square inche, that is, the region is a high density recording region. In case that the recording density is less than this, a conventional MR head using an anisotropic magnetoresistive (AMR) effect can be used sufficiently. That is, the GMR head usable practically is a head in which a high density recording and reproducing being more than 3 G bits per square inch can be realized. A magnetic recording and reproducing apparatus using the GMR head is a high density magnetic recording and reproducing apparatus that realizes the high density recording and reproducing being more than 3 G bits per square inch.
Not limited to the GRM head, an ID head having a recording function on a magnetic recording medium has been always required that its high density recording performance must be increased. Especially, in order to realize the high density recording, it is necessary that the magnetic recording medium has a high coercive force. Because a magnetic transition length recording on the magnetic recording medium is made to be short corresponding to the increase of the recording density, magnetization must be stable even as magnetization length per bit is made to be short. Consequently, in order that the ID head can record on a high coercive force magnetic recording medium being suitable for high density recording, the development to increase the recording magnetic field has been energetically promoted.
Conventionally, a plated film Ni—Fe, in which Ni is about 80 weight % (hereinafter referred to as 80Ni—Fe), has been used for a magnetic core of the ID head. This material has about 1 T (tesla) saturation magnetization (Bs), and can execute recording of 3 G bits per square inch. This is described in a technical report written by C. Tsang et al., “3 Gb/in
2
Recording Demonstration with Dual Element Heads & Thin Film Disks,” IEEE Trans. Mag., Vol. 32, No. 1, 1996, pp. 7-12.
However, in order to perform recording of more than 5 G bits per square inches, a plated film Ni—Fe, in which Ni is about 45 weight % (hereinafter referred to as 45Ni—Fe) is required, instead of the 80Ni—Fe. This is described in a technical report written by C. Tsang et al., “5 Gb/in
2
Recording Demonstration with Conventional AMR Dual Element Heads & Thin Film Disks,” IEEE Trans. Mag., Vol. 33, No. 5, 1997, pp. 2866-2871. This material has saturation magnetization about 1.6 T at maximum. Further, recording of about 12 G bits per square inches can be executed by using this material is described in a technical report written by C. Tsang et al., “12 Gb/in
2
recording demonstration with SV read heads & conventional narrow pole-tip write heads,” IEEE Trans. Mag., Vol. 35, No. 2, 1999, pp. 689-694.
In Japanese Patent Applications Laid-Open No. HEI 8-212512 and HEI 11-16120, a Ni—Fe plated film having about 1.6 T saturation magnetization (Bs) is described. And in Japanese Patent Application Laid-Open No. HEI 10-162322, it is described that a Co type amorphous material represented by Co—Ta—Zr sputtered film is used as a high saturation magnetization (Bs) material. About 1.5 T being the high saturation magnetization (Bs) is possible by using a Co type amorphous film. And in Japanese Patent Application Laid-Open No. HEI 7-262519, a high saturation magnetization (Bs) material such as ferric nitride is applied. About 1.9 T being the high saturation magnetization (Bs) is possible by using a Fe—N type material.
In order to achieve simplification and low cost at manufacturing processes of a magnetic head, it is effective that a magnetic material forming a recording magnetic core is formed by a plating method. At the plating method, a photo resist frame, in which a pattern of a magnetic core is pressed, is formed beforehand, and a desired pattern can be obtained by making a plated film grow in this photo resist frame. This method is now a standard manufacturing method of a thin film magnetic head because of its simplicity and low cost.
In case that the magnetic core pattern is formed by a sputtering method, a photo resist mask is formed on a magnetic film formed beforehand
Honjo Hiroaki
Ishi Tsutomu
Ishiwata Nobuyuki
Nonaka Yoshihiro
Saito Mikiko
Evans Jefferson
Foley & Lardner
NEC Corporation
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