Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
2002-02-11
2004-07-13
Tupper, Robert S. (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Core
Reexamination Certificate
active
06762911
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a combination type thin film magnetic head having an inductive type thin film magnetic head element serving as a writing magnetic converting element and a magnetoresistive type thin film magnetic head element serving as a reading magnetic converting element stacked one on the other, and a method of manufacturing the same. More particularly, the present invention relates to an inductive type writing thin film magnetic head having a narrow record track for attaining a high surface recording density on a magnetic record medium by utilizing magnetic materials having a high saturation magnetic flux density, and a method of manufacturing the same.
2. Description of the Related Art
Recently a surface recording density of a hard disc device has been improved, and it has been required to develop a thin film magnetic head having an improved performance accordingly. A recent magnetoresistive type thin film magnetic head using a GMR (Giant Magneto-Resistive) element has a surface recording density up to 100 gigabits/inch
2
. A combination type thin film magnetic head is constructed by stacking an inductive type thin film magnetic head intended for writing information on a magnetic record medium and a magnetoresistive type thin film magnetic head intended for reading information out of the magnetic record medium on a substrate. As a reading magnetoresistive element, a GMR element having a magnetoresistive change larger than a normal anisotropic MR element by 5-15 times has been used. In order to improve a performance of the GMR element, there have been various proposals.
In a normal anisotropic MR element, a single film of a magnetic material showing the magnetoresistive effect is utilized. Many GMR elements have a multi-layer structure having a stack of a plurality of films. There are several mechanisms for generating a resistance change in the GMR element, and the multi-layer structure is dependent upon a mechanism. For instance, a super-lattice GMR film and a glanular film have a simple structure and a large resistance change under a weak magnetic field. A spin-valve GMR film will be suitable for a large scale manufacture.
As stated above, a desired high surface recording density can be simply attained by changing the AMR element by the GMR element as long as the reproducing thin film magnetic head is concerned, and a surface recording density could be further increased by utilizing a magnetic material having a higher magnetoresistive sensitivity. A performance of a reproducing head element is also dependent upon a pattern width in addition to the above mentioned selection of material. The pattern width includes a MR height and track width. A track width is determined by a photolithography process and a MR height is determined by an amount of polishing for forming an air bearing surface (ABS).
At the same time, the performance of the recording magnetic head is also required to be improved in accordance with the improvement of the performance of the reproducing magnetic head. In order to increase a surface recording density, it is necessary to realize a high track density on a magnetic record medium. To this end, a pole portion of the recording thin film magnetic head element has to be narrowed in a sub-micron order by utilizing the semiconductor manufacturing process. However, upon decreasing a track width by utilizing the semiconductor manufacturing process, there is a problem that a sufficiently large magnetic flux could not be obtained due to a miniaturized structure of the pole portion. In order to solve such a problem, there has been proposed to make at least a pole portion of a recording head element of a magnetic material having a high saturation flux density (Hi-Bs material).
FIGS. 1-5
show successive steps of a method of manufacturing a conventional combination type thin film magnetic head. In these drawings, A represents a cross sectional view cut along a plane perpendicular to the air bearing surface ABS and B denotes a cross sectional view of a pole portion cut along a plane parallel to the air bearing surface ABS.
FIG. 6
is a plan view showing schematically the structure of the known combination type thin film magnetic head.
As shown in
FIG. 1
, an alumina (Al
2
O
3
) insulating film
12
having a thickness of about 2-3 &mgr;m is deposited on a substance
11
made of AlTiC. Next, a bottom shield film
13
made of a magnetic material for magnetically shielding a GMR reading head element from an external magnetic field. On the bottom shield film
13
, a shield gap film
14
made of alumina is formed with a thickness of 300-350 Å by sputtering. Then, a GMR film
15
having a given layer-structure is formed, and lead electrodes
16
for the GMR film are formed by a lift-off process. Next, a top shield gap film
17
made of alumina is formed with a thickness of 300-350 Å by sputtering, and a magnetic film
18
serving as a top shield film is formed with a thickness of about 3 &mgr;m.
Next, an isolation film
19
made of alumina is formed with a thickness of about 0.3 &mgr;m for isolating the reading GMR head element from a writing induction type thin film magnetic head element to suppress noise in a reproduced output from the GMR head element. After that, a bottom pole
20
of the recording head element made of permalloy is formed with a thickness of 1.5-2.0 &mgr;m as illustrated in FIG.
1
. It should be noted that in the drawings a ratio of thickness of various portions does not exactly correspond to an actual ratio. For instance, the isolation film
19
is shown to have a smaller thickness.
Next, as depicted in
FIG. 2
, on the bottom pole
20
, is formed a write gap film
21
having a thickness of about 2000 Å, and a top pole
22
made of permalloy which is a magnetic material having a high saturation magnetic flux density is formed in accordance with a given pattern. At the same time, a bridge film
23
for magnetically coupling the bottom pole
20
with the top pole
22
at a back-gap is formed. The top pole
22
and bridge film
23
are formed by plating with a thickness of about 3-4 &mgr;m.
Then, in order to avoid a widening of an effective track width, i.e. in order to prevent a magnetic flux from extending at the bottom pole
20
during a writing operation, the write gap film
21
and the underlying bottom pole
20
around the top pole
22
are etched by ion milling to form a so-called trim structure. After that, forming an alumina insulating film
24
having a thickness of about 3 &mgr;m over a whole surface, a surface is flattened by the chemical mechanical polishing (CMP) as shown in FIG.
3
.
Next, as illustrated in
FIG. 4
, a thin film coil
25
is formed on the flattened surface by the electrolytic plating of Cu in accordance with a given pattern, and an insulating film
26
which supports the thin film coil
25
in an electrically insolated manner is formed by photoresist. Next, as depicted in
FIG. 5
, a top pole
28
made of permalloy is formed with a thickness of about 3 &mgr;m such that the top pole
22
and bridge film
23
are coupled with each other by the top pole
28
. Next, a whole surface is covered with an overcoat film
29
made of alumina. It should be noted that during the formation of the top pole
28
, an electrically conductive film
29
for connecting the thin film coil
25
to an external circuit is formed with a same magnetic material as that of the top pole
28
. Finally, an end surface into which the GMR film
15
, write gap film
21
, top pole
22
and so on are exposed is polished to form an air bearing surface ABS to complete a slider.
FIG. 6
shows a cross sectional view and a plan view illustrating the structure of the known combination type thin film magnetic head manufactured in the manner explained above. The bottom pole
20
has a large area, but the top poles
22
and
28
have a smaller area than the bottom pole. One of factors determining the performance of the writing head element is a throat height TH. The throat hei
Kamigama Takehiro
Sasaki Yoshitaka
Headway Technologies Inc.
Tupper Robert S.
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