Dynamic magnetic information storage or retrieval – Head – Magnetoresistive reproducing head
Reexamination Certificate
2000-10-12
2003-12-02
Ometz, David L. (Department: 2653)
Dynamic magnetic information storage or retrieval
Head
Magnetoresistive reproducing head
C360S271000
Reexamination Certificate
active
06657824
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates to a magnetoresistive effect magnetic head which reads signals recorded on a magnetic recording medium by using magnetoresistive effect. The present invention also relates to a rotary magnetic head apparatus using the magnetoresistive effect magnetic head and to a manufacturing method of this rotary magnetic head apparatus.
2. Prior Art
In recent years, recording densities are increasing in the field of magnetic recording. Instead of bulk heads, thin film heads are widely used as magnetic heads suited for high density recording. A thin film head is manufactured through the use of manufacturing techniques in the field of semiconductor integrated circuits, more specifically film formation techniques such as vaporization, sputtering, and the like, and photolithography techniques such as photoengraving, etching, and the like. These techniques make it possible to form a fine shape with high precision to mass-produce heads. Thin film heads having these advantages are currently mainstreamed as magnetic heads for high-density recording/reproducing systems such as hard disks, tape streamers, and the like.
Of these thin film heads, a magnetoresistive effect magnetic head (referred to hereafter as an MR head) is now in wide use as a magnetic reproducing head on hard disk drives and the like. The MR head reads signals using magnetoresistive effect.
A magnetoresistive effect element (referred to hereafter as an MR element) provides the magnetoresistive effect. The MR head comprises the MR element formed in a gap according to the thin film formation. The width of a thin film MR element determines the track width, easily providing narrow tracks. The MR head provides higher read sensitivity than a coil-type inductive head. Owing to no influence of inductance, the MR head can transfer signals at high-frequencies. The MR head is considered to be an essential device for high-density recording/reproducing systems in the future.
The following describes a configuration example of a magnetic head conventionally used for a hard disk drive with reference to
FIGS. 1 through 3
. A magnetic head
100
is formed as a so-called composite magnetic head comprising an MR head for reproduction and an inductive head for recording which are layered on each other. The magnetic head
100
is mounted on a floating slider
200
which floats above a magnetic disk. The magnetic head
100
is positioned so that a magnetic sensor is exposed from an air bearing surface (ABS)
201
of a floating slider
200
to a magnetic disk's signal recording surface.
Specifically, the magnetic head
100
is provided with a substrate
102
made of Al—TiC and the like on which a base film
101
made of Al
2
O
3
and the like is formed. On the substrate
102
where the base film
101
is formed, there is formed a soft magnetic film of Sendust and the like which functions as a lower magnetic shield thin film
103
. A nonmagnetic nonconductive film
104
of Al
2
O
3
and the like is formed on the substrate
102
where the lower magnetic shield thin film
103
is not formed. The nonmagnetic nonconductive film
104
is as thick as the lower magnetic shield thin film
103
.
Another nonmagnetic nonconductive film of Al
2
O
3
and the like is formed on the lower magnetic shield film
103
and the nonmagnetic nonconductive film
104
to function as a lower shield gap film
105
. On the lower shield gap film
105
, an SAL bias layer, an intermediate layer, and an MR layer are laminated to form an MR element
106
. The MR element
106
is positioned at one side (a face against a medium) of the magnetic head
100
so that one end of the MR element
106
is exposed outward from the air bearing surface
201
of the floating slider
200
.
On both ends of the MR element
106
in the track direction, there is formed a pair of ferromagnetic films
107
and
108
for making a magnetic domain for the MR element
106
to be single-domain and suppressing a Barkhausen noise. On the ferromagnetic films
107
and
108
, there is formed a pair of resistance decreasing films
124
and
125
for decreasing resistance of the MR element
106
and a portion electrically connected to the MR element
106
.
On the lower shield gap film
105
, there is provided a pair of conductors
109
and
110
for supplying the MR element
106
with a sense current. One end of the conductors
109
and
110
is connected to a pair of ferromagnetic films
107
and
108
. The pair of conductors
109
and
110
is electrically connected to the MR element
106
via the pair of ferromagnetic films
107
and
108
.
On the other end of the pair of conductors
109
and
110
, there are provided external connection terminals
111
and
112
which are connected to an external circuit. End faces of the external connection terminals
111
and
112
are exposed outward. Lead wires and the like are connected to these end faces.
On the lower shield gap film
105
, there are formed the MR element
106
, the ferromagnetic films
107
and
108
, the conductors
109
and
110
, and the like. In a manner which covers these elements, a nonmagnetic nonconductive film of Al
2
O
3
and the like is also formed on the lower shield gap film
105
and functions as an upper shield gap film
113
. On the upper shield gap film
113
, a soft magnetic film of Permalloy and the like is formed and functions as an upper magnetic shield thin film
114
.
The above-mentioned portions on the magnetic head
100
constitute an MR head for reproduction. The magnetic head
100
allows the soft magnetic film in the form of the upper magnetic shield thin film
114
to function as a lower-layer core for the inductive head for recording. Namely, the soft magnetic film of Permalloy and the like formed on the upper shield gap film
113
functions as an upper magnetic shield thin film for the MR head and as a lower-layer core for the inductive head.
The soft magnetic film functions as a lower-layer core for the inductive head. A nonmagnetic nonconductive film of Al
2
O
3
and the like is formed on the soft magnetic film and is used as a recording gap film
115
. On the recording gap film
115
, a thin film coil
117
is formed at a position far away from a face against a medium so that the coil
117
is embedded in an insulating film
116
. As shown in
FIG. 1
, the coil
117
is connected to a pair of conductors
118
and
119
and external connection terminals
120
and
121
through which a drive current is supplied.
A soft magnetic film of Permalloy and the like is formed on the recording gap film
115
from a position facing a medium to a position far away from that position. The soft magnetic film functions as an upper-layer core
122
.
Namely, at the side facing a medium on the magnetic head
100
, there is provided the recording gap film
115
sandwiched by the lower-layer core
114
and the upper-layer core
122
which face to each other. At a position far away from the side facing a medium, the coil
117
is provided between the lower-layer core
114
and the upper-layer core
122
. The soft magnetic film functions as the upper-layer core
122
on the magnetic head
100
. At a position farthest from the face against a medium, the upper-layer core
122
is connected to the soft magnetic film functioning as the lower-layer core
114
.
The above-mentioned portions on the magnetic head
100
constitute an inductive head for recording. As the top layer on the magnetic head
100
, there is formed a nonmagnetic nonconductive film of Al
2
O
3
and the like functioning as a protection layer
123
.
The magnetic head
100
according to the above-mentioned configuration is formed at the side of the floating slider
200
so that the face against the medium is positioned at the side of the air bearing surface
201
of the floating slider
200
. When the floating slider
200
floats above a magnetic disk, the magnetic head
100
reads or writes signals onto the magnetic disk. At this time, part of the MR element
5
in the MR head as the magnetic sensor and
Ometz David L.
Sonnenschein Nath & Rosenthal LLP
Sony Corporation
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