Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
2001-10-09
2004-06-01
Tugbang, A. Dexter (Department: 3729)
Metal working
Method of mechanical manufacture
Electrical device making
C029S603070, C029S603160, C029S603180, C029S605000, C360S123090, C360S125330, C360S317000, C216S039000, C216S041000, C451S005000, C451S041000
Reexamination Certificate
active
06742242
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to a thin film magnetic head for writing and a method of manufacturing the same, and more particularly relates to a combination type thin film magnetic head including an inductive type thin film magnetic head for writing and a magnetoresistive type magnetic head for reading, said magnetic heads being supported by a substrate in a stacked fashion.
2. Description of 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.
There has been proposed and actually used a combination type thin film magnetic head including an inductive type thin film magnetic head for writing and a magnetoresistive type magnetic head for reading, said magnetic heads being supported by a substrate in a stacked fashion. As the reading magnetic head utilizing the magnetoresistive effect, there has been generally used a reading magnetic head utilizing an anisotropic magnetoresistive (AMR) effect, but there has been also developed a magnetic head utilizing a giant magnetoresistive (GMR) effect having a resistance change ratio higher than the normal anisotropic magnetoresistive effect by several times.
In the present specification, these AMR and GMR elements are termed as a magnetoresistive type thin film magnetic head or simply MR reproducing element.
By using the AMR reproducing element, a very high surfacerecording density of several gigabits per a unit square inch has been realized, and a surface recording density can be further increased by using the GMR element. By increasing a surface recording density in this manner, it is possible to realize a hard disc device which has a very large storage capacity of more than 10 gigabytes and is still small in size.
A height (MR Height: MRH) of a magnetoresistive reproducing element is one of factors which determine a performance of a reproducing head including a magnetoresistive reproducing element. This MR height MRH is a distance measured from an air bearing surface on which one edge of the magnetoresistive reproducing element is exposed to the other edge of the element remote from the air bearing surface. During a manufacturing process of the magnetic head, a desired MR height MRH is obtained by controlling an amount of polishing the air bearing surface.
At the same time, a performance of a recording head has been also required to be improved. In order to increase a surface recording density, it is necessary to make a track density on a magnetic record medium as high as possible. For this purpose, a width of a pole portion at the air bearing surface has to be reduced to a value within a range from several micron meters to several submicron meters. In order to satisfy such a requirement, the semiconductor manufacturing process has been adopted for manufacturing the thin film magnetic head.
One of factors determining a performance of an inductive type thin film magnetic film for writing is a throat height (TH). This throat height TH is a distance of a pole portion measured from the air bearing surface to an edge of an insulating layer which serves to separate electrically a thin film coil from the air bearing surface. It has been required to shorten this distance as small as possible. Also this throat height TH is determined by an amount of polishing the air bearing surface.
In order to improve the performance of the combination type thin film magnetic head including a stack of an inductive type thin film magnetic head for writing and a magnetoresistive type thin film magnetic head for reading, it is important that the inductive type thin film magnetic head for writing and magnetoresistive type thin film magnetic head for reading are formed with a good balance.
FIGS. 1-11
show successive steps of manufacturing a known typical thin film magnetic head, in which A represents a cross sectional view cut along a plane perpendicular to the air bearing surface and B denotes a cross sectional view cut along a plane parallel with the air bearing surface.
FIGS. 12-14
are a cross sectional view illustrating a completed thin film magnetic head, a cross sectional view of the pole portion, and a plan view depicting the whole magnetic head. This magnetic head belongs to a combination type thin film magnetic head which is constructed by stacking an inductive type thin film writing magnetic head and a magnetoresistive type thin film reading magnetic head one on the other.
At first, as illustrated in
FIG. 1
, on a substrate
1
made of, for instance aluminum-titan-carbon (AlTiC), is deposited an insulating layer
2
made of alumina (Al
2
O
3
) and having a thickness of about 5-10 &mgr;m.
Then, as depicted in
FIG. 2
, a first magnetic layer
3
constituting one of magnetic shields for protecting the MR reproducing magnetic head from external magnetic fields is formed to have a thickness of 3 &mgr;m on the insulating layer.
Then, after depositing by sputtering a shield gap layer
4
made of an alumina with a thickness of 100-150 nm as shown in
FIG. 3
, a magnetoresistive layer
5
having a thickness of several tens nano meters and being made of a material having the magnetoresistive effect, and the magnetoresistive layer is shaped into a desired pattern by a highly precise mask alignment.
Next, as represented in
FIG. 4
, a second shield gap layer
6
made of an alumina is formed to embed the magnetoresistive layer
5
within the shield gap layers
4
,
6
.
Next, as shown in
FIG. 5
, a second magnetic layer
7
made of a permalloy and having a thickness of 3 &mgr;m is formed. This magnetic layer
7
serves not only as the other shield layer (top shield) for magnetically shielding the MR reproducing element together with the above mentioned first magnetic layer
3
, but also as one of poles (bottom pole) of the inductive type writing thin film magnetic head to be manufactured later.
Next, after forming, on the second magnetic layer
7
, a write gap layer
8
made of a nonmagnetic material such as alumina to have a thickness of about 200 nm and a given pattern. After forming a magnetic layer made of a magnetic material having a high saturation magnetic flux density such as permalloy (Ni 50%: Fe 50%) and iron nitride (FeN), this magnetic layer is shaped into a given pattern by a highly precise mask alignment to form a pole chip
9
. A width W of the pole chip
9
defines a track width. Therefore, in order to attain the high surface recording density, it is necessary to narrow the width W of the pole chip
9
as small as possible.
During the formation of the pole chip
9
, a dummy pattern
9
′ for connecting the second magnetic layer
7
constituting the bottom pole with a third magnetic layer
16
constituting the top pole is formed. This dummy pattern, makes the formation of a through hole easy after mechanical polishing or chemical-mechanical polishing (CMP).
Then, in order to prevent an increase of an effective track width, that is, in order to prevent a spread of a magnetic flux at the lower pole during a writing operation, the gap layer
8
and second magnetic layer
7
constituting the bottom pole in a vicinity of the pole chip
9
are removed by an ion beam etching such as an ion milling. This condition is shown in
FIG. 5
, and the thus formed structure is called a trim structure, and the trim structure constitutes a pole portion of the second magnetic layer.
Furthermore, as depicted in
FIG. 6
, an insulating layer
10
made of an alumina is formed to have a thickness of about 3 &mgr;m, and then an assembly is flattened by CMP. Then, after forming an electrically insulating photoresist layer
11
in accordance with a given pattern by a highly precise mask alignment, a first layer thin film coil
12
made of, for instance a copper is formed on the insulating layer
11
.
Next, as depicted in
FIG. 7
, after forming an insulating photoresist layer
13
on the first layer thin film coil
12
by a highly precise mask alignment, a surface of the photores
Kim Paul D
Oliff & Berridg,e PLC
TDK Corporation
Tugbang A. Dexter
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