Etching a substrate: processes – Forming or treating article containing magnetically...
Reexamination Certificate
1999-05-24
2002-07-16
Gulakowski, Randy (Department: 1746)
Etching a substrate: processes
Forming or treating article containing magnetically...
C216S058000, C216S066000, C216S074000, C216S075000, C216S076000, C216S077000, C216S063000, C029S603150, C029S603130, C029S603180, C360S324000
Reexamination Certificate
active
06419845
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of etching a magnetic layer made of high saturated flux density materials, a method of forming a magnetic pole of a thin film magnetic head having at least an inductive-type magnetic transducer for writing and a method of manufacturing a thin film magnetic head.
2. Description of the Related Art
Performance improvement in thin film magnetic heads has been sought in accordance with an increase in surface recording density of a hard disk device. A composite thin film magnetic head, which is made of a layered structure including a recording head with an inductive-type magnetic transducer for writing and a reproducing head with a magnetoresistive (MR) element for reading, is widely used as a thin film magnetic head. As MR elements there are an anisotropic magnetoresistive (AMR) element that utilizes the AMR effect and a giant magnetoresistive (GMR) that utilizes the GMR effect. A reproduction head using the AMR element is called an AMR head or simply an MR head. A 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 more than 1 gigabit per square inch. The GMR head is used as a reproducing head whose surface recording density is more than 3 gigabit per square inch.
The AMR head includes an AMR film having the AMR effect. In the GMR head, the AMR film is replaced with a GMR film having the GMR effect and the configuration of the GMR head is similar to that of the AMR head. However, the GMR film exhibits a greater change in resistance under a specific external magnetic field compared to the AMR film. Therefore, the reproducing output of the GMR head is about three to five times as great as that of the AMR head.
The MR film may be changed in order to improve the performance of a reproducing head. In general, the AMR film is made of a magnetic substance that exhibits the MR effect and has a single-layered structure. In contrast, many of the GMR films have a multi-layered structure consisting of a plurality of films. There are several types of mechanisms which produce the GMR effect and the layer structure of the GMR film changes depending on the mechanism. The GMR films include a superlattice GMR film, a granular film, a spin valve film and so on. The spin valve film is most efficient for the GMR film which has a relatively simple structure, exhibits a great change in resistance in a low magnetic field, and is suitable for mass production. The performance of a reproducing head is thus easily improved by, for example, changing the MR film from the AMR film to the GMR film and so on which are the materials with an excellent magnetoresistive sensitivity.
As a primary factor for determining the performance of a recording head, there is a pattern width, especially an MR height, in addition to the selection of a material described above. The MR height is the length (height) between the end of an MR element closer to an air bearing surface and the other end. The MR height is originally controlled by an amount of grinding when the air bearing surface is processed. The air bearing surface (ABS) here is a surface of a thin film magnetic head that faces a magnetic recording medium and is also called a track surface.
Performance improvement in a recording head has also been expected in accordance with the performance improvement in a reproducing head. It is required to increase the track density of a magnetic recording medium in order to increase the recording density among the performance of a recording head. In order to achieve this, a recording head of a narrow track structure in which the width of a bottom pole and a top pole being formed sandwiching a write gap on the air bearing surface is required to be reduced to the order of few microns to submicron. Semiconductor process technique is used to achieve the narrow track structure.
Another factor for determining the performance of a recording head is the throat height (TH). The throat height is the length (height) of a portion (magnetic pole portion) which is from the air bearing surface to an edge of an insulating layer which electrically isolates the thin film coil. Reducing the throat height is desired in order to improve the performance of a recording head. The throat height is also controlled by an amount of grinding when the air bearing surface is processed.
In order to improve the performance of a thin film magnetic head, it is important to form a recording head and a reproducing head in well balance as described.
Here, a cross sectional configuration of a composite thin film magnetic head as an example of a thin film magnetic head of the related art is described with reference to FIG.
28
A and FIG.
28
B. In
FIG. 28
, “A” shows a cross section vertical to a track surface and “B” shows a cross section of a magnetic pole portion parallel to the track surface. The magnetic head
100
comprises a magnetoresistive reading head portion (called a reading head portion in the following)
100
A for reproducing and an inductive recording head (called a recording head in the following)
100
B for recording.
The reading head portion
100
A is a pattern of a magnetoresistive layer (called an MR layer in the following)
105
being formed on a substrate
101
made of, for example, ALTIC (Al
2
O
3
·TiC) through an undercoating layer
102
formed with, for example, alumina (aluminum oxide, Al
2
O
3
), a bottom shield layer
103
formed with, for example, ferrous aluminum silicide (FeAlSi), and a shield gap layer
104
formed with, for example, aluminum oxide (AM
2
0
., called alumina in the following) in order. Further, a lead terminal layer
105
a
made of a material which does not diffuse into the MR films such as tantalum (Ta), tungsten (W) and so on is formed on the shield gap layer
104
. The lead terminal layer
105
a
is electrically connected to an MR layer
105
. The MR layer
105
is formed with various kinds of materials having magnetoresistive effect such as permalloy (NiFe alloy), nickel (Ni)—cobalt (Co) alloy and so on. A shield gap layer
106
made of, for example, alumina is laminated on the MR layer
105
and the lead terminal layer
105
a
. That is, the MR layer
105
and the lead terminal layer
105
a
are buried between the shield gap layers
104
and
106
.
The recording head portion
100
B comprises a top pole
109
a
being formed on the reading head portion
100
A through a bottom pole
107
which functions as a top shield layer of the MR layer
105
and a gap layer
108
. An insulating layer
110
is formed on the gap layer
108
, and a first layer of a thin film coil
111
and a second layer of a thin film coil
112
are laminated on the insulating layer
110
. The thin film coils
111
and
112
are respectively formed on the shield layers lila and
112
a
by plating method. The thin film coils
111
and
112
are covered with the insulating layers
113
and
114
. A top pole layer
109
including the top pole
109
a
is formed on the insulating layers
110
,
113
and
114
. The top pole layer
109
is covered with an overcoat layer
115
. In the recording head portion
100
B, a bottom pole
107
a
facing the top pole
109
a
has a trim structure in which part of the surface of the top shield layer
107
is processed to be protruded.
In the magnetic head
100
, reading-out of information from a magnetic disk which is not shown in figure is performed in the recording head portion
100
A using magnetoresistive effect of the MR layer
105
, while writing of information to a magnetic disk is performed in the recording portion
100
B using a change in magnetic flux between the top pole
109
a
and the bottom pole
107
a.
FIG.
29
A and
FIG. 29B
to
FIG. 38
show an example of a method of manufacturing another composite thin film magnetic head of the related art.
First, as shown in FIG.
29
A and
FIG. 29B
, an insulating layer
202
made of, for example, alumina (aluminum oxide, Al
2
O
3
) of about 5-10 &mgr;m in thickness is deposited on a subst
Gulakowski Randy
Kornakov Michail
TDK Corporation
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