Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
2001-09-17
2003-12-30
Vo, Peter (Department: 3729)
Metal working
Method of mechanical manufacture
Electrical device making
C029S603110, C029S603130, C029S603150, C029S603160, C029S603170, C300S013000, C300S013000, C451S005000, C451S041000
Reexamination Certificate
active
06668442
ABSTRACT:
BACKFGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a thin film magnetic head having at least an inductive-type magnetic transducer for writing and a method of manufacturing the same.
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 having an inductive-type magnetic transducer for writing and a reproducing head having magnetoresistive (MR) elements for reading, is widely used as a thin film magnetic head. The MR elements includes an anisotropic magnetoresistive (AMR) element that utilizes the AMR effect and a giant magnetoresistive (GMR) element that utilizes the GMR effect. A reproducing head using an 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.
In general, an AMR film is made of a magnetic substance that exhibits the MR effect and has a single-layered structure. In contrast, most of GMR films have a multi-layered structure consisting of a plurality of films. There are several types of mechanisms which produces the GMR effect. The layer structure of a GMR film depends on the mechanism. The GMR films include a super-lattice GMR film, a spin valve film, a granular film and so on, while the spin valve film is most efficient as 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 reproduction.
As a primary factor for determining the performance of a reproducing head, there is a pattern width, especially an MR height. 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 sandwiching a write gap on the air bearing surface is required to be reduced to the order of some microns to submicron. Semiconductor process technique is used to achieve the narrow track structure.
Another factor 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 controlled as well 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 the recording head and the reproducing head as described in well balance.
Here, an example of a manufacturing method of a composite thin film magnetic head as an example of a thin film magnetic head of a related art is to be described with reference to
FIGS. 31A and 31B
to
FIGS. 36A and 36B
.
As shown in
FIGS. 31A and 31B
, an insulating layer
102
made of, for example, alumina (aluminum oxide, Al
2
O
3
of about 5 to 10 &mgr;m in thickness is formed on a substrate
101
made of, for example, aluminum oxide and titanium carbide (Al
2
O
3
.TiC). Further, a bottom shield layer
103
for a reproduction head made of, for example, permalloy (NiFe) is formed on the insulating layer
102
.
Next, as shown in
FIGS. 32A and 32B
, for example, alumina of about 100~200 nm in thickness is deposited on the bottom shield layer
103
to form a shield gap film
104
. Then, 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 photolithography with high precision is applied to obtain a desired shape. Next, a lead terminal layer
106
facing the MR film
105
is formed by lift-off method. Next, a shield gap film
107
is formed on the shield gap film
104
, the MR film
105
and the lead terminal layer
106
, and the MR film
105
and the lead terminal layer
106
are buried in the shield gap layers
104
and
107
. Next, a top shield-cum-bottom pole (called bottom pole in the followings)
108
of about 3 &mgr;m in thickness made of, for example, permalloy (NiFe), which is a material used for both of a reproduction head and a recording head, is formed on the shield gap film
107
.
Next, as shown in
FIGS. 33A and 33B
, a write gap layer
109
of about 200 nm in thickness made of an insulating layer such as an alumina film is formed on the bottom pole
108
. Further, an opening
109
a
for connecting the top pole and the bottom pole is formed through patterning the write gap layer
109
by photolithography. Next, a pole tip
110
is formed with magnetic materials made of permalloy (NiFe) and nitride ferrous (FeN) through plating method, while a connecting portion pattern
110
a
of the top pole and the bottom pole is formed. The bottom pole
108
and a top pole layer
116
which is to be described later are connected by the connecting pattern
110
a
and so that forming a through hole after CMP (Chemical and Mechanical Polishing) procedure which is to be described later becomes easier.
Next, as shown in
FIGS. 34A and 34B
, the write gap layer
109
and the bottom pole
108
are etched about 0.3~0.5 &mgr;m by ion milling having the pole tip
110
as a mask. By etching the bottom pole
108
, a trim structure is formed. As a result, widening of effective write track width can be avoided (that is, suppressing widening of magnetic flux at the bottom pole when data is being written). Next, after an insulating layer
111
of about 3 &mgr;m, made of, for example, alumina is formed all over the surface, the whole surface is flattened by CMP.
Next, as shown in
FIGS. 35A and 35B
, a first layer of a thin film coil
112
for inductive-type recording heads made of, for example, copper (Cu) is selectively formed on the insulating layer
111
by, for example, plating method. Further, a photoresist film
113
is formed in a desired pattern on the insulating layer
111
and the thin film coil
112
by photolithography with high precision. Further, a heat treatment of desired temperature is applied for flattening the photoresist film
113
and insulating between the thin film coils
112
. Likewise, a second layer of a thin film coil
114
and a photoresist film
115
are formed on the photoresist film
113
, and a heat treatment of desired temperature is applied for flattening the photoresist film
115
and insulating between the thin film coils
114
.
Next, as shown in
FIGS. 36A and 36B
, a top pole yoke-cum-top pole layer (called a top pole layer in the followings)
116
made of, for example, permalloy, which is a magnetic material for recording heads, is formed on the top pole
110
, the photoresist films
113
and
115
. The top pole layer
116
has a contact with the bottom pole
108
in a position rear of the thin film coils
112
and
114
, and is magnetically coupled to the bottom pole
108
. Further, an over coat layer
117
made of, for example, alumina is formed on the top pole layer
116
. At last, a track surface (air bearing surface) of recording heads and reproducing heads is formed throug
Kim Paul
Oliff & Berridg,e PLC
TDK Corporation
Vo Peter
LandOfFree
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