Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
1999-12-13
2002-03-12
Letscher, George J. (Department: 2652)
Metal working
Method of mechanical manufacture
Electrical device making
C360S317000
Reexamination Certificate
active
06353995
ABSTRACT:
BACKGROUND 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 to a method of manufacturing the same.
2. Description of the Related Art
Recently, an improvement in performance of thin film magnetic heads has been sought in accordance with an increase in a surface recording density of a hard disk drive. A composite thin film magnetic head, which has a stacked structure of a recording head having an inductive-type magnetic transducer for writing and a reproducing head having a magnetoresistive effect element (hereinafter referred to as an MR element) for reading-out, is widely used as the thin film magnetic head. MR elements include an AMR element using a magnetic film exhibiting an anisotropic magnetoresistive effect (hereinafter referred to as an AMR effect) and a GMR element using a magnetic film exhibiting a giant magnetoresistive effect (hereinafter referred to as a GMR effect). The reproducing head using the AMR element is called an AMR head or simply an MR head, and the reproducing head using the GMR element is called a GMR head. The AMR head is used as the reproducing head whose surface recording density exceeds 1 gigabit per square inch, and the GMR head is used as the reproducing head whose surface recording density exceeds 3 gigabits 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, many of the GMR films have a multi-layered structure consisting of a plurality of films. There are several types of producing mechanisms of the GMR effect. The layer structure of the GMR film depends on the mechanism. A super lattice GMR film, a spin valve film, a granular m and the like are proposed as the GMR film. Of these types of films, the spin valve film is most efficient as the GMR film which is relatively simple in structure, exhibits a great change in resistance in a low magnetic field, and is suitable for mass-production.
A pattern width, especially an MR height is a primary factor for determining the performance of a reproducing head. The MR height is the length (height) between the end of the MR element closer to an air bearing surface and the other end. The MR height is originally controlled by the amount of polishing during the process of the air bearing surface. The air bearing surface (ABS) is a surface of a thin film magnetic head facing a magnetic recording medium and is also called a track surface.
An improvement in performance of a recording head has also been expected in accordance with the improvement in performance of a reproducing head. It is necessary to increase the track density of the magnetic recording medium in order to increase the recording density among the performance of the recording head. In order to achieve this, it is necessary to develop the recording head with a narrow track structure, the width of a bottom magnetic pole (bottom pole) and a top magnetic pole (top pole) sandwiching a write gap on the air bearing surface being reduced to the order of several microns to submicron. The semiconductor process technique is used to achieve the narrow track structure.
The throat height (TH) is another factor for determining the performance of the recording head. The throat height is the length (height) between the air bearing surface and an edge of an insulating layer (magnetic pole portion) which electrically isolates the thin film coil. Reducing the throat height is desired in order to improve the performance of the recording head. The throat height is also controlled by the amount of polishing during the process of the air bearing surface.
In order to improve the performance of the thin film magnetic head, it is important to form the recording head and the reproducing head in well balance.
An example of a method of manufacturing a composite thin film magnetic head will be described with reference to
FIGS. 26A and 26B
through
FIGS. 31A and 31B
as an example of a thin film magnetic head of the related art.
As shown in
FIGS. 26A and 26B
, an insulating layer
202
made of, for example, alumina (aluminum oxide, Al
2
O
3
) is formed with about 5 to 10 &mgr;m thick on a substrate
201
made of, for example, altic (Al
2
O
3
. TiC). Subsequently, a bottom shield layer
203
for the reproducing head made of, for example, permalloy (NiFe) is formed on the insulating layer
202
.
As shown in
FIGS. 27A and 27B
, for example, alumina of about 100-200 nm in thickness is deposited on the bottom shield layer
203
to form a shield gap film
204
. An MR film
205
of tens of nanometers in thickness for making up the MR element for reproducing is formed on the shield gap film
204
, and high-precision photolithography is applied to obtain a desired shape. A lead terminal layer
206
for the MR film
205
is formed by lift-off. A shield gap film
207
is formed on the shield gap film
204
, the MR film
205
and the lead terminal layer
206
, and the MR film
205
and the lead terminal layer
206
are buried in the shield gap films
204
and
207
. A top shield-cum-bottom pole (hereinafter referred to as a bottom pole)
208
of about 3 &mgr;m in film thickness made of a magnetic material used for both the reproducing head and the recording head such as permalloy (NiFe) is formed on the shield gap film
207
.
As shown in
FIGS. 28A and 28B
, a write gap layer
209
of about 200 nm in film thickness made of an insulating layer such as an alumina film is formed on the bottom pole
208
. Further, an opening
209
a
for connecting the top pole and the bottom pole is formed through patterning the write gap layer
209
by photolithography. A pole tip
210
is formed of the magnetic materials consisting of permalloy (NiFe) and nitride ferrous (FeN) through plating with a connecting portion pattern
210
a
for connecting the top pole and the bottom pole. The bottom pole
208
and a top pole layer
216
which will be described hereinafter are connected by the connecting portion pattern
210
a
and therefore forming a through hole after CMP (Chemical and Mechanical Polishing) process, which will be described later, becomes easier.
As shown in
FIGS. 29A and 29B
, the write gap layer
209
and the bottom pole
208
are etched about 0.3 to 0.5 &mgr;m by ion milling having the pole tip
210
as a mask. By etching to the bottom pole
208
, a trim structure is formed. As a result, the widening of effective write track width can be avoided (that is, suppressing the spread of magnetic flux in the bottom pole when data is being written). Subsequently, after an insulating layer
111
with a film thickness of about 3 &mgr;m, made of, for example, alumina is formed over the whole surface and then the surface is planarized by CMP.
As shown in
FIGS. 30A and 30B
, a thin film coil
212
of a first layer for an inductive-type recording head made of, for example, copper (Cu) is selectively formed on the insulating layer
211
by, for example, plating. On the insulating layer
211
and the thin film coil
212
, a photoresist film
213
is formed in a desired pattern by high-precision photolithography. A heat treatment of a predetermined temperature is applied to planarize the photoresist film
213
and to insulate between the turns of the thin film coil
212
. Similarly, a thin film coil
214
of a second layer and a photoresist film
215
are formed on the photoresist film
213
, and the heat treatment of a predetermined temperature is applied to planarize the photoresist film
215
and to insulate between the turns of the thin film coil
214
.
As shown in
FIGS. 31A and 31B
, a top yoke-cum-top pole layer (hereinafter referred to as a top pole layer)
216
made of the magnetic material for recording heads, for example, permalloy is formed on the pole tip
210
and the photoresist films
213
and
215
. The top pole layer
216
is in contact with the bottom pole
208
in a rearward position of the thin film coils
212
and
214
, and magnetically coupled to the bottom pole
20
Iijima Atsushi
Sasaki Yoshitaka
Letscher George J.
Oliff & Berridg,e PLC
TDK Corporation
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