Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
1999-06-14
2002-01-29
Cao, Allen (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Core
Reexamination Certificate
active
06342990
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for forming a magnetic pole layer of a thin film magnetic head having at least an induction type magnetic transducer, a thin film magnetic head and a method for manufacturing the same.
2. Description of the Related Art
Recent improvement of the surface recording density of hard disk drives has resulted in demands for improved performance of thin film magnetic heads. Commonly used thin film magnetic heads are composite thin film magnetic heads having a structure in which a recording head having an induction type magnetic transducer for writing and a reproduction head having a magnetoresistive (hereinafter referred to as “MR”) element for reading are stacked into layers. MR elements include AMR elements utilizing the anisotropic magnetoresistive (hereinafter referred to as “AMR”) effect and GMR elements utilizing the giant magnetoresistive (hereinafter referred to as “GMR”) effect. A reproduction head utilizing an AMR element is referred to as “AMR head” or simply as “MR head”, and a reproduction head utilizing a GMR element is referred to as “GMR head”. An AMR head is used as a reproduction head having a surface recording density in the excess of 1 gigabit/inch
2
, and a GMR head is used as a reproduction head having a surface recording density in the excess of 3 gigabit/inch
2
.
An AMR head has an AMR film having the AMR effect. A GMR head has the same structure as that of an AMR head except that the AMR film is replaced with a GMR film having the GMR effect. When exposed to the same external magnetic field, the resistance of a GMR film changes more significantly than that of an AMR film. Therefore, it is said that the reproduction output of a GMR head can be about 3 to 5 times greater than that of an AMR head.
One method for improving the performance of a reproduction head is to change the MR film. In general, an AMR film is a film which is made of a magnetic material having the MR effect and which has a single-layer structure. On the contrary, most GMR films have a multi-layer structure which is a combination of a plurality of films. The GMR effect produces several types of mechanisms, and the layer structures of GMR films depend on the mechanisms. GMR films proposed in the past include superlattice GMR films, granular films and spin valve films, and spin valve films are promising as GMR films which must have a relatively simple configuration, which must exhibit significant fluctuation of resistance even in a weak magnetic field and which are to be mass-produced. Therefore, the purpose of improving the performance of a reproduction head can be easily achieved by, for example, changing the material of the MR film from an AMR film to a GMR film or the like having excellent sensitivity to magnetoresistance.
Factors that determine the performance of a reproduction head other than the choice of the material as described above include the pattern widths, especially MR height. MR height is the length (height) of an MR element from the end thereof where the air bearing surface (surface facing the medium) is located to the opposite end thereof. The MR height is essentially controlled by the amount of lapping during the processing of the air bearing surface.
The trend toward reproduction heads having improved performance has resulted in a need for improvement of recording heads. In order to improve the performance of a recording head especially the recording density, the track density of the magnetic recording medium must be increased. For this purpose, it has been desired to provide a recording head having a narrow track structure by processing a magnetic layer for forming an top magnetic pole on a submicron basis utilizing semiconductor processing techniques.
Another factor that determines the performance of a recording head is the throat height. Throat height is the length (height) of a region that extends from the air bearing surface to an edge of an insulation layer for electrically isolating a thin film coil (the region is referred to as “magnetic pole portion” in this application). There is a need for a reduction of the throat height to improve the performance of a recording head. The throat height is also controlled by the amount of lapping during the processing of the air bearing surface.
As described above, in order to improve the performance of a thin film magnetic head, it is important to form the recording and reproduction heads with preferable balance between them.
A description will now be made with reference to
FIGS. 26 through 36
on an example of a method for manufacturing a composite thin film magnetic head according to the related art.
FIGS. 26 through 36
show a section perpendicular to an air bearing surface.
According to the manufacturing method, as shown in
FIG. 26
, an insulation layer
102
made of, for example, alumina (Al
2
O
3
) is deposited on a substrate
101
made of, for example, aluminum oxide and titanium carbide (Al
2
O
3
.TiC) to a thickness in the range from about 5 to 10 &mgr;m. Next, as shown in
FIG. 27
, a bottom shield layer
103
for a reproduction head is formed on the insulation layer
102
.
As shown in
FIG. 28
, for example, alumina is then deposited on the bottom shield layer
103
to a thickness in the range from 100 to 200 nm by means of sputtering to form a shield gap film
104
. Then, an MR film
105
for forming an MR element for reproduction is formed on the shield gap film
104
to a thickness of several tens nm and is patterned into a desired configuration using photolithography with high accuracy. As shown in
FIG. 29
, a shield gap film
106
is then formed on the shield gap film
104
and MR film
105
to embed the MR film
105
between the shield gap films
104
and
106
.
Next, as shown in
FIG. 30
, a tom shield layer-cum-bottom magnetic pole layer (hereinafter referred to as “bottom magnetic pole layer”)
107
made of a magnetic material, e.g., permalloy (NiFe) to be used for both of reproduction and recording heads is formed on the shield gap film
106
.
As shown in
FIG. 31
, a recording gap layer
108
constituted by an insulation film, e.g., an alumina film, is then formed on the bottom magnetic pole layer
107
, and a photoresist layer
109
is formed on the recording gap layer
108
in a predetermined pattern using photolithography with high accuracy. Next, a first layer thin film coil
110
for an induction type recording head made of, for example, copper (Cu) is formed on the photoresist layer
109
using a plating process.
Next, as shown in
FIG. 32
, a photoresist layer
111
is formed on the photoresist layer
109
and coil
110
in a predetermined pattern using photolithography with high accuracy. Then, a heating process is performed at a temperature of, for example, 250° C. to planarize the photoresist layer
111
and to provide insulation at the gaps of the coil
110
.
Next, as shown in
FIG. 33
, a second layer thin film coil
112
made of, for example, copper is formed on the photoresist layer
111
using, for example, a plating process. Then, a photoresist layer
113
is formed on the photoresist layer
111
and coil
112
in a predetermined pattern using photolithography with high accuracy, and a heating process is performed at a temperature of, for example, 250° C. to planarize the photoresist layer
113
and to provide insulation at the gaps of the coil
112
.
Next, as shown in
FIG. 34
, the recording gap layer
108
is partially etched for forming a magnetic path in a position behind (right-hand side in
FIG. 34
) the coils
110
and
112
. Then, a top magnetic pole layer
114
made of a magnetic material, e.g., permalloy, for the recording head is formed on the recording gap layer
108
and photoresist layers
109
,
111
and
113
. The top magnetic pole layer
114
is in contact with the bottom magnetic pole layer
107
in a position behind the coils
110
and
112
to be magnetically coupled therewith. Next, the recording gap layer
108
and bottom magnetic pole layer
107
are etched by about 0.5 &
Cao Allen
Oliff & Berridg,e PLC
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