Dynamic magnetic information storage or retrieval – Head – Magnetoresistive reproducing head
Reexamination Certificate
1999-05-24
2003-07-22
Ometz, David L. (Department: 2653)
Dynamic magnetic information storage or retrieval
Head
Magnetoresistive reproducing head
C360S125330
Reexamination Certificate
active
06597543
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an inductive-type thin-film magnetic head and a magnetic storage apparatus using the magnetic head.
2. Description of the Prior Art
Recently, the recording density of a hard disk drive has been remarkably improved. A recording density after 1990 tends to rise at an annual rate of approx. 60%. To improve the recording density of a hard disk drive, it is preferable to improve the recording track density by decreasing the track width of a magnetic head. Moreover, to improve the recording density, improvement of the recording bit density is similarly important. To improve the recording bit density, it is preferable to increase the resistance to applied magnetic force (Hc) of a magnetic storage medium. Moreover, to write data in a magnetic storage medium having a high Hc, it is preferable to use an inductive recording head having a high recording capacity. Furthermore, to efficiently detect a signal from micro-scaled recording bits, it is preferable to use an MR reproducing head. Therefore, an MR-inductive composite-type thin-film magnetic head obtained by combining an MR reproducing head with an inductive recording head is prospective for high-density recording.
FIG. 19
is a sectional view of a conventional thinfilm magnetic head. The conventional thin-film magnetic head will be hereafter described by referring to FIG.
19
.
A conventional thin-film magnetic head
70
is constituted by laminating a lower shielding layer
74
, a read gap layer
80
holding an MR magnetosensitive element
78
in an ABS plane
76
, a common pole layer
82
serving as an upper shielding layer and a lower pole layer, and a write gap layer
84
in order on an insulating substrate
72
, then laminating a first flattening layer
86
, a coil pattern layer
88
, and a second flattening layer
90
in order on the write gap layer
84
excluding the vicinity of the ABS plane
76
, and by laminating an upper pole layer
92
on the write gap layer
84
, first flattening layer
86
, and second flattening
90
nearby the ABS plane
76
.
The common pole layer
82
serves as an upper shielding layer for improving the reproducing resolution of an MR reproducing head and a lower pole layer of an inductive recording head. The MR magnetosensitive element
78
detects a signal magnetic field from a not-illustrated magnetic storage medium facing the ABS plane
76
. The thickness of the write gap layer
84
serves as the gap of the inductive recording head. The first flattening layer
86
serves as the insulating base of the coil pattern layer
88
and the second flattening layer
90
corrects the irregular height difference in the coil pattern layer
88
. The portion free from the first flattening layer
86
on the write gap layer
84
nearby the ABS plane
76
specifies the gap depth D of the inductive recording head. The recording track width is determined by the front end portion width W (not illustrated) of the upper pole layer
92
. The front end portion width W represents the width of the upper pole layer
92
on the ABS plane (front end) in the direction vertical to a drawing surface, which is illustrated in FIG.
2
and the like.
To improve the recording capacity under high-density recording, it is preferable to decrease the gap depth D to 1 &mgr;m or less. Moreover, to correspond to high-density recording, it is preferable to realize the upper pole layer
92
having a minimum front end portion width W.
Furthermore, an invention for improving the recording density is disclosed in the official gazette of Japanese Patent Application Laid-Open No. 9-305930. This invention attains its object by using a magnetic recording/reproducing head configured by superimposing a sealed-type MR head on an inductive-type magnetic recording head and thereby, improving the accuracy of widths of the recording coil and recording track of an upper recording head.
BRIEF SUMMARY OF THE INVENTION
OBJECT OF THE INVENTION
To form a necessary gap depth D, it is preferable to form the first flattening layer
86
considerably nearing the ABS plane
76
side, determining the gap depth D. Therefore, the conventional thin-filmmagnetic head
70
has the following problem when forming a resist frame pattern (not illustrated) for forming the upper pole layer
92
through the frame plating method.
The first flattening layer
86
, coil pattern layer
88
, and the second flattening layer
90
are successively superimposed and then, a resist frame pattern is formed. In this case, a large height difference is formed between the write gap layer
84
and the second flattening layer
90
at the front end portion. Therefore, the thickness of the resist film of the resist frame pattern at the front end portion reaches 10 &mgr;m or more. Moreover, the front end of the first flattening layer
86
is formed into a curved surface. Therefore, when light for exposure reflects on the curved surface, the resist frame pattern could easily be overexposed.
Thus, the resist frame pattern for forming the front end portion of the upper pole layer
92
tends to have a large film thickness and it is easily overexposed. Therefore, obtaining a necessary gap depth D makes it difficult to obtain a necessary front-end portion width W.
SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to provide a thin-film magnetic head capable of accurately decreasing a gap depth D and a front-end portion width W and a magnetic storage apparatus using the magnetic head.
The thin-film magnetic head in claim
1
of the present invention is constituted by laminating a write gap layer on a lower pole layer, forming a first flattening layer, a coil pattern layer, and a second flattening layer in order on the write gap layer excluding an ABS plane, and forming an upper pole layer on the write gap layer at least at near the ABS plane. Moreover, a concave portion is formed on the lower pole layer at a position separated from the ABS plane, the concave portion is filled with a non magnetic body, and the gap depth between the upper pole layer and the lower pole layer is determined by the concave portion.
The gap depth is not determined by the distance from the ABS plane to the front end of the first flattening layer but it is determined by the distance from the ABS plane to the margin of the concave portion. Since the concave portion is formed on a flat lower pole layer, no problem occurs in the photolithography process for forming the concave portion. Moreover, the resist frame pattern for forming the front end portion of the upper pole layer is not increased in film thickness nor is it overexposed because the first flattening layer can be sufficiently separated from the ABS plane.
The thin-film magnetic head in claim
2
of the present invention is constituted by laminating a lower shielding layer, a read gap layer holding an MR magnetosensitive element in an ABS plane, a common pole layer serving as an upper shielding layer and a lower pole layer, and a write gap layer in order on an insulating substrate, then laminating a first flattening layer, a coil pattern layer, and a second flattening layer in order on the write gap layer excluding the vicinity of the ABS plane, and then forming at least an upper pole layer on the write gap layer nearby the ABS plane. Moreover, a concave portion is formed on the common pole layer at a position separated from the ABS plane, the concave portion is filled with a nonmagnetic body, and the gap depth between the upper pole layer and the lower pole layer is determined by the concave portion. That is, the thin-film magnetic head in claim
2
is an MR-inductive composite-type thin-filmmagnetic head obtained by combining an MR reproducing head with an inductive recording head.
The thin-film magnetic heads of claims
3
to
29
are constituted by restricting some components of the thin-film magnetic head of claim
1
or
2
. The magnetic storage apparatus of claim
14
uses the thin-film magnetic head in claim
1
or 2.
REFERENCES:
patent: 5111352 (1992-05-0
Ishiwata Nobuyuki
Nonaka Yoshihiro
Saitho Shinsaku
Shimabayashi Kiyotaka
Toba Tamaki
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