Dynamic magnetic information storage or retrieval – Head – Magnetoresistive reproducing head
Reexamination Certificate
2000-09-12
2002-07-02
Evans, Jefferson (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Magnetoresistive reproducing head
C360S319000, C360S125330
Reexamination Certificate
active
06414824
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a thin film magnetic head having at least an inductive magnetic transducer for writing and a method of manufacturing the same.
2. Description of the Related Art
In recent years, an improvement in performance of a thin film magnetic head is demanded in association with an increase in surface recording density of a hard disk drive. As a thin film magnetic head, a composite thin film magnetic head in which a recording head having an inductive-type magnetic transducer for writing and a reproducing head having a magnetoresistive (hereinbelow, referred to as MR) element for reading are stacked is widely used.
One of factors which determine the performances of the recording head is throat height (TH). The throat height is a length (height) of a magnetic pole from the air bearing surface to the edge of an insulating layer for electrically isolating a thin film coil for generating a magnetic flux. The air bearing surface is a surface of a thin film magnetic head, which faces a magnetic recording medium and is also called a track surface. In order to improve the performances of the recording head, reduction in throat height is desired. The throat height is controlled by a polishing amount at the time of processing the air bearing surface.
In order to improve the recording density in the performances of the recording head, it is necessary to increase track density of a magnetic recording medium. For this purpose, it is necessary to realize a recording head of a narrow track structure in which the width on the air bearing surface of each of a bottom pole and a top pole formed while sandwiching a write gap is reduced to the order of a few microns to submicrons. In order to achieve this, semiconductor processing techniques are used.
Referring now to
FIGS. 30
to
35
, as an example of a method of manufacturing a conventional thin film magnetic head, a method of manufacturing a composite thin film magnetic head will be described.
According to the manufacturing method, first, as shown in
FIG. 30
, an insulating layer
102
made of, for example, alumina (Al
2
O
3
) is deposited in thickness of about 5 to 10 &mgr;m on a substrate
101
made of altic (Al
2
O
3
with TiC) or the like. Subsequently, a bottom shield layer
103
for a reproducing head is formed on the insulating layer
102
. For example, alumina is then deposited by sputtering in thickness of 100 to 200 nm on the bottom shield layer
103
to form a shield gap film
104
. An MR film
105
for constructing an MR device for reproduction is deposited on the shield gap film
104
and is patterned in a desired shape by high-precision photolithography. Then lead layers (not shown) as lead electrode layers which are electrically connected to the MR film
105
are formed on both sides of the MR film
105
. After that, a shield gap film
106
is formed on the lead layers, the shield gap film
104
, and the MR film
105
, and the MR film
105
is buried in the shield gap films
104
and
106
. An upper shield-cum-bottom pole (hereinbelow, referred to as a bottom pole)
107
made of a magnetic material such as Permalloy (NiFe) used for both of the reproducing head and the recording head is formed on the shield gap film
106
.
As shown in
FIG. 31
, on the bottom pole
107
, a write gap layer
108
made of an insulating material such as alumina is formed. On the write gap layer
108
, a thin film coil
109
for an inductive recording head made of, for example, copper (Cu) is formed by plating or the like. Subsequently, a photoresist layer
110
is formed in a predetermined pattern by high-precision photolithography so as to cover the thin film coil
109
. In order to flatten the thin film coil
109
and insulate turns of the thin film coil
109
from each other, a heat treatment is performed at, for example, 250°
As shown in
FIG. 32
, in a position rearward of the thin film coil
109
(right side in FIG.
32
), an opening
108
a
is formed by partially etching the write gap layer
108
in order to form a magnetic path. Then, a top yoke-cum-top magnetic pole (hereinbelow, called a top pole)
111
made of a magnetic material such as Permalloy for the recording head is selectively formed on the write gap layer
108
and the photoresist layer
110
. The top pole
111
is in contact with and magnetically coupled to the bottom pole
107
in the opening
108
a
. The top pole
111
is used as a mask and the write gap layer
108
and the bottom pole
107
are etched by about 0.5 &mgr;m through ion milliing. After that, an overcoat layer
112
made of, for example, alumina is formed on the top pole
111
. Finally, a slider is machined to thereby form a track surface (air bearing surface)
120
of the recording head and the reproducing head. In such a manner, a thin film magnetic head is completed.
FIGS. 33
to
35
show the structure of the thin film magnetic head in a completed state.
FIG. 33
is a cross section of the thin film magnetic head perpendicular to the air bearing surface
120
.
FIG. 34
is an enlarged cross section parallel to the air bearing surface
120
of the pole part.
FIG. 35
is a plan view. Each of
FIGS. 30
to
33
is a cross section taken along line A-A′ of FIG.
35
. In
FIGS. 33
to
35
, the overcoat layer
112
is not shown.
In order to improve the performance of the thin film magnetic head, it is important to form the head with accurate throat height TH, apex angle &thgr;, pole width P
2
W and pole length P
2
L shown in
FIGS. 33 and 34
. The apex angle &thgr; is an angle formed by a straight line which is in contact with a side face on the track face side of the photoresist layer
110
and the top face of the top pole
111
. The pole width P
2
W defines the width of a recording track on a recording medium. The pole length P
2
L indicates the thickness of the pole. In
FIGS. 33 and 35
, “TH
0
position” denotes the edge on the track face side of the photoresist layer
110
as an insulating layer which electrically isolates the turns of the thin film coil
109
, that is, a reference position
0
of the throat height TH.
As shown in
FIG. 34
, a structure in which side walls of the top pole
111
, the write gap layer
108
and a part of the bottom pole
107
are formed vertically in a self-aligned manner is called a trim structure. According to the trim structure, an increase in the effective track width due to expansion of the magnetic flux which occurs at the time of writing data to a narrow track can be prevented. As shown in
FIG. 34
, lead layers
121
as a lead electrode layer electrically connected to the MR film
105
are provided on both sides of the MR film
105
. In
FIGS. 30
to
33
, the lead layers
121
are omitted.
FIG. 36
shows the structure in plan view of the top pole
111
. As shown in the diagram, the top pole
111
has a yoke
111
a
which occupies a major part of the top pole
111
and a pole tip
111
b
having an almost constant width W
100
as the pole width P
2
W. In the coupling portion between the yoke
111
a
and the pole tip
111
b
, the outer periphery of the yoke
111
a
forms an angle a to a plane parallel to the air bearing surface
120
. In the coupling portion, the outer periphery of the pole tip
111
b
forms an angle &bgr; to a plane parallel to the air bearing surface
120
. For example, a is about 45 degrees and &bgr; is 90 degrees. The width of the pole tip
111
b
defines the width of a recording track on a recording medium. The pole tip
111
b
includes a portion F on the front side (the air bearing surface
120
side) with respect to the position TH
0
and a portion R on the rear side (on the yoke
111
a
side) with respect to the position TH
0
. As understood from
FIG. 33
, the portion F extends on the flat write gap layer
108
, and the portion R and the yoke
111
a
extend on a coil portion (hereinbelow, called an “apex portion” which is covered with the photoresist layer
110
and is raised like a mountain).
The shape of the top pole is described in, for example, Japanese Unexamine
Evans Jefferson
TDK Corporation
LandOfFree
Thin film magnetic head having a shield layer adjacent a gap... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Thin film magnetic head having a shield layer adjacent a gap..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Thin film magnetic head having a shield layer adjacent a gap... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2882010