Etching a substrate: processes – Forming or treating article containing magnetically...
Reexamination Certificate
2001-01-22
2003-12-30
Utech, Benjamin L. (Department: 1765)
Etching a substrate: processes
Forming or treating article containing magnetically...
C029S603130, C029S603150, C029S603180, C360S112000
Reexamination Certificate
active
06669855
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of manufacturing a thin-film magnetic head having at least an inductive-type magnetic transducer for writing.
2. Description of the Related Art
Improvements in the performance of a thin-film magnetic head have been sought since a surface recording density of a hard disk drive has been improved. A composite thin-film magnetic head having a structure in which, a recording head having an inductive-type magnetic transducer for writing and a reproducing head having a magnetoresistive (hereinafter referred to as MR) element for reading are stacked, is widely used as the thin-film magnetic head. The MR element includes an AMR element using an anisotropic magnetoresistive (hereinafter referred to as AMR) effect and a GMR element using a giant magneto resistive (hereinafter referred to as GMR) effect. The reproducing head using the AMR element is called an AMR head or simply an MR head, and the reproducing head using the GMR element is called a GMR head. The AMR head is used as a reproducing head whose surface recording density is over 1 gigabit per square inch, and the GMR head is used as the reproducing head whose surface recording density is over 3 gigabit per square inch.
The AMR head comprises an AMR film having the AMR effect. The GMR head has a structure identical to the AMR head except that a GMR film having the GMR effect is used in place of the AMR film. However, when the same external magnetic field is applied, the GMR film exhibits greater change in resistance than the AMR film. As a result, the GMR head can increase the reproduction output in the order of three to five times the AMR head.
In order to improve the performance of the reproducing head, a method of replacing the AMR film with a material having better magnetoresistive sensitivity such as the GMR film as the MR film, a method of making an appropriate pattern width of the MR film, especially the MR height and other methods are employed. The MR height is a distance between an end of the MR element on the air bearing surface side to an end thereof on the other side, and it is controlled by a polishing amount in processing the air bearing surface. The air bearing surface, here, is a surface of the thin film magnetic head facing a magnetic recording medium, and is called a track surface as well.
On the other hand, improvements in performance of a recording head have been desired while performance in a reproducing head has improved. A factor which determines the performance of the recording head is a throat height. The throat height is a length of a pole between the air bearing surface and an edge of an insulating layer which electrically separates a thin-film coil for generating magnetic flux. The throat height is desired to be optimized in order to improve the performance of the recording head. The throat height is controlled by a polishing amount in processing the air bearing surface.
To improve a recording density among the performance of the recording head, a track density of the magnetic recording medium needs to be increased. In order to achieve such an increase, a recording head with a narrow track structure needs to be realized in which a width of the top and bottom poles on the air bearing surface, which are formed on top and bottom sandwiching a write gap, is reduced from the order of some microns to sub-microns. Semiconductor process techniques are employed to achieve the narrow track structure.
A method of manufacturing the composite thin-film magnetic head as an example of the methods of manufacturing the thin-film magnetic head of the related art will be described by referring to FIG.
27
through FIG.
32
.
As shown in
FIG. 27
, in this manufacturing method, an insulating layer
102
made of, for example, aluminum oxide (Al
2
O
3
; hereinafter referred to simply as “alumina”) of about 5 &mgr;m to 10 &mgr;m in thickness is deposited on a substrate
101
made of, for example, altic (aluminum oxide and titanium carbide; Al
2
O
3
.TiC). A bottom shield layer
103
for a reproducing head is formed on the insulating layer
102
. A shield gap film
104
is formed on the bottom shield layer
103
by, for example, sputter-depositing alumina with 100 nm to 200 nm in thickness. An MR film
105
of tens of nanometers in thickness for making up the MR element for reproduction is formed on the shield gap film
104
, and patterned in a desired shape through photolithography with high precision. Next, after forming lead layers (not shown) on both sides of the MR film
105
as an extraction electrode layer which is electrically connected to the MR film
105
, a shield gap film
106
is formed on the lead layer, the shield gap film
104
and the MR film
105
, and then the MR film
105
is buried in the shield gap films
104
and
106
. Further, a top shield-cum-bottom pole (hereinafter referred to simply as a bottom pole)
107
made of magnetic materials, such as ferronickel (NiFe; hereinafter referred to simply as “permalloy” (trade name)) used for both reproduction and recording heads is formed on the shield gap film
106
.
As shown in
FIG. 28
, a write gap layer
108
made of an insulating material, such as alumina, is formed on the bottom pole
107
, and a photoresist film
109
in a desired pattern is formed on the write gap layer
108
through photolithography with high precision. Next, a thin-film coil
110
for an inductive-type recording head made of, for example, copper (Cu) is formed on the photoresist film
109
by, for example, plating. A photoresist film
111
in a desired pattern is formed covering the photoresist film
109
and the thin-film coil
110
through photolithography with high precision. Next, the photoresist film
111
is subjected to a heat treatment at a temperature of, for example, 250° C. to have turns of the coil
110
insulated from each other.
As shown in
FIG. 29
, an opening
108
a
is formed by partially etching the write gap layer
108
in a position behind the coil
110
(right-hand side in
FIG. 29
) to expose part of the bottom pole
107
in order to form a magnetic path. A film of a magnetic material with a high saturation magnetic flux density, such as permalloy, is formed by an electrolytic plating, covering the exposed surface of the bottom pole
107
, and the photoresist film
111
and the write gap layer
108
. The plated film formed of permalloy is selectively etched by ion milling using a mask (not shown) formed of a photoresist film having a prescribed planar shape, to thereby form a top yoke-cum-top pole (hereinafter referred to as a top pole)
112
. The top pole
112
has, for example, such a planar shape as shown in
FIG. 32
, which will be described hereinafter, and includes a yoke
112
a
and a pole tip
112
b.
The top pole
112
has a contact with the bottom pole
107
in the opening
108
a
being magnetically coupled. Next, after both the write gap layer
108
and the bottom pole
107
are partially etched about 0.5 &mgr;m by ion milling using part of the top pole
112
(the pole tip
112
b
) as a mask (see FIG.
31
), an overcoat layer
113
is formed of a material, such as alumina, on the top pole
112
. The thin-film magnetic head is completed after a track surface, that is, air bearing surface
120
of the recording head and reproducing head is formed by machining or polishing.
FIG.
30
through
FIG. 32
show a completed configuration of the thin-film magnetic head.
FIG. 30
shows a cross-sectional view of the thin-film magnetic head orthogonal to the air bearing surface
120
,
FIG. 31
is an enlarged cross-sectional view of the pole in parallel to the air bearing surface
120
, and
FIG. 32
is a plan view.
FIG. 29
is a cross sectional view taken along the line XXIX—XXIX in FIG.
32
. Illustrations of the overcoat layer
113
and the like are omitted in
FIG. 30
to FIG.
32
. The thin-film coil
110
shown in
FIG. 32
is only the outermost periphery portion thereof, and the photoresist film
111
shown therein is only the outermost end thereof.
In FIG.
Iijima Atsushi
Kanakubo Katsuya
Sasaki Yoshitaka
Yari Seiji
Ahmed Shamim
Oliff & Berridg,e PLC
TDK Corporation
Utech Benjamin L.
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