Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
2000-12-01
2004-01-20
Letscher, George J. (Department: 2653)
Dynamic magnetic information storage or retrieval
Head
Core
C360S313000
Reexamination Certificate
active
06680815
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The 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
Recently, an improvement in performance of a thin film magnetic head has been sought in accordance with an increase in a surface recording density of a hard disk device. A composite thin film magnetic head is widely used as the thin film magnetic head. The composite thin film magnetic head has a laminated structure comprising a recording head having an inductive magnetic transducer for writing and a reproducing head having a magnetoresistive (hereinafter referred to as MR) element for reading. MR elements include an AMR element utilizing an anisotropic magnetoresistive (AMR) effect and a GMR element utilizing a giant magnetoresistive (GMR) effect. Methods of improving the performance of the reproducing head include a method in which an MR film is changed from an AMR film to a material having excellent sensitivity to magnetic resistance, such as a GMR film; a method in which a pattern width of the MR film, particularly, an MR height is appropriately set; and so on. The MR height means a length (height) of the MR element between the end thereof close to an air bearing surface and the opposite end thereof. The MR height is controlled in accordance with an amount of air bearing surface to be polished in working the air bearing surface. The air bearing surface means the surface of the thin film magnetic head facing a magnetic recording medium. The air bearing surface is sometimes called a track surface.
On the other hand, the improvement in the performance of the recording head is also sought in accordance with the improvement in the performance of the reproducing head. Factors for determining the performance of the recording head include a throat height (TH). The throat height means the length (height) of a magnetic pole portion between the air bearing surface and an edge of an insulating layer for electrically isolating thin film coils for generating a magnetic flux. A reduction in the throat height is desired for the improvement in the performance of the recording head. The throat height is also controlled in accordance with the amount of air bearing surface to be polished in working the air bearing surface.
The increase in a recording density of the performance of the recording head requires the increase in a track density of the magnetic recording medium. For this purpose, it is necessary to implement the recording head having a narrow track structure. In this structure, a bottom pole and a top pole are formed on the bottom and the top of a write gap, respectively, with the write gap sandwiched therebetween, and the bottom and top poles have a narrow width of from a few microns to the submicron order on the air bearing surface. Technology for fabricating a semiconductor is used in order to achieve this structure.
One example of the method of manufacturing the composite thin film magnetic head will be now described as one example of the method of manufacturing the thin film magnetic head of the related art with reference to
FIGS. 32
to
37
.
In this manufacturing method, first, as shown in
FIG. 32
, an insulating layer
102
made of alumina (Al
2
O
3
), for example, is deposited with a thickness of about 5 &mgr;m to 10 &mgr;m on a substrate
101
made of altic (Al
2
O
3
and TiC), for example. Then, a lower shield layer
103
for the reproducing head is formed on the insulating layer
102
. Then, alumina, for example, is sputter deposited with a thickness of 100 nm to 200 nm on the lower shield layer
103
, whereby a shield gap film
104
is formed. Then, an MR film
105
for constituting the MR element for reproducing is formed with a thickness of tens of nanometers on the shield gap film
104
. The MR film
105
is patterned into a desired shape by high-accuracy photolithography. Then, a lead layer (not shown) for functioning as a lead electrode layer to be electrically connected to the MR film
105
is formed on both sides of the MR film
105
. Then, a shield gap film
106
is formed on the lead layer, the shield gap film
104
and the MR film
105
, whereby the MR film
105
is embedded in the shield gap films
104
and
106
. Then, an upper shield-cum-bottom pole (hereinafter referred to as a bottom pole)
107
made of a magnetic material for use in both of the reproducing and recording heads, e.g., permalloy (NiFe) is formed on the shield gap film
106
.
Then, as shown in
FIG. 33
, a write gap layer
108
made of an insulating film, e.g., an alumina film is formed on the bottom pole
107
. Thin film coil
110
made of, for example, copper (Cu) for an inductive recording head is formed on the write gap layer
108
by plating method, for example. Then, a photoresist layer
111
is formed into a predetermined pattern by the high-accuracy photolithography so that the thin film coil
110
may be coated with the photoresist layer
111
. Then, heat treatment takes place at a temperature of, for instance, 250° C. in order to provide planarization of the thin film coil
110
and insulation among the thin film coil
110
. Then, thin film coil
112
made of, for example, copper is formed on the photoresist layer
111
. A photoresist layer
113
is formed so as to cover the thin film coil
112
.
Then, as shown in
FIG. 34
, the write gap layer
108
is partially etched at the rear of the thin film coils
110
and
112
(on the right side in
FIG. 34
) in order to form a magnetic path, whereby an opening
108
a
is formed. Then, an upper yoke-cum-top pole (hereinafter referred to as a top pole)
114
made of the magnetic material for the recording head, e.g., permalloy is selectively formed on the write gap layer
108
and a photoresist layer
113
. The top pole
114
is in contact with and magnetically coupled to the bottom pole
107
in the above-mentioned opening
108
a
. Then, the write gap layer
108
and the bottom pole
107
are etched by about 0.5 &mgr;m by means of ion milling using the top pole
114
as a mask. Then, an overcoat layer
115
made of alumina, for example, is formed on the top pole
114
. Finally, a slider is machined, whereby a track surface (air bearing surface)
120
of the recording head and the reproducing head is formed. As a result, the thin film magnetic head is completed.
FIGS. 35
to
37
show the structure of the completed thin film magnetic head.
FIG. 35
shows a cross section of the thin film magnetic head perpendicular to the air bearing surface
120
.
FIG. 36
shows an enlarged view of the cross section of the magnetic pole portion parallel to the air bearing surface
120
.
FIG. 37
shows a plan view.
FIG. 34
corresponds to the cross section along line XXXIVA—XXXIVA of FIG.
37
. The overcoat layer
115
is not shown in
FIGS. 35
to
37
.
To improve the performance of the thin film magnetic head, it is important to precisely form a throat height TH, an apex angle &thgr;, a pole width P
2
W and a pole length P
2
L shown in
FIGS. 35 and 36
. The apex angle &thgr; means the angle between a line tangent to side surfaces of the photoresist layers
109
,
111
and
113
close to the track surface and an upper surface of the top pole
114
. The pole width P
2
W defines a recording track width on the recording medium. The pole length P
2
L represents the thickness of the magnetic pole. In
FIGS. 35 and 37
, a ‘TH
0
position’ means the edge of the insulating layer (the photoresist layer
109
) under the thin film coils
110
, close to the track surface. The TH
0
position indicates a reference position
0
of the throat height TH.
The structure, in which the respective partial side walls of the top pole
114
, the write gap layer
108
and the bottom pole
107
are vertically formed in self-alignment as shown in
FIG. 36
, is called a trim structure. This trim structure allows a prevention of the increase in an effective track width resulting from a spread of the magnetic flux generated during the writing o
Blouin Mark
Letscher George J.
Oliff & Berridg,e PLC
TDK Corporation
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