Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
2001-12-21
2004-06-08
Ometz, David L. (Department: 2653)
Dynamic magnetic information storage or retrieval
Head
Core
C029S603150, C029S603180
Reexamination Certificate
active
06747842
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a thin film magnetic head having an inductive-type magnetic transducer for writing and a method of manufacturing the same.
2. Description of the Related Art
Improvements in the performance of a thin film magnetic head have been sought since an areal density of a hard disk drive has been improved. A composite thin film magnetic head having a structure, in which a recording head having an inductive-type magnetic transducer for writing and a reproducing head having a magnetoresistive (hereinafter referred to as MR) element for reading are stacked, is widely used as the thin film magnetic head.
FIGS. 25A and 25B
show an example of a cross sectional structure of a conventional thin film magnetic head. This thin film magnetic head includes, for example, a substrate
101
formed of altic (aluminum oxide and titanium carbide; Al
2
O
3
.TiC), an insulating layer
102
formed of aluminum oxide (Al
2
O
3
; hereinafter simply referred to as “alumina”), a bottom shield layer
103
formed of ferronickel alloy (NiFe; hereinafter simply referred to as “permalloy” (trade name)), shield gap films
104
and
106
for burying an MR film
105
, a top shield layer serving as a bottom pole (hereinafter simply referred to as a “bottom pole”)
107
, a write gap layer
108
having an opening
108
K, a thin film coil
109
formed of copper (Cu) for generating magnetic flux, an insulating layer
110
formed of photoresist for insulating the thin film coil
109
from the adjacent elements, a top pole
111
magnetically coupled to the bottom pole
107
through the opening
108
K and forming a propagation path for magnetic flux (magnetic path) with the bottom pole
107
, and an overcoat layer
112
serving as a cap film, stacked in this order from the bottom. The shield gap films
104
and
106
, the write gap layer
108
, and the overcoat layer
112
are formed of, for example, a material similar to that of the insulating layer
102
, and the bottom pole
107
and the top pole
111
are formed of, for example, a material similar to that of the bottom shield layer
103
.
The top pole
111
and the bottom pole
107
have the same uniform width in the vicinity of the write gap layer
108
located in a region closer to a recording-medium-facing surface (air bearing surface)
120
facing a magnetic recording medium (hereinafter simply referred to as a “recording medium”), and these portions form a pole portion
200
defining a recording track width. This pole portion
200
is formed by, for example, forming the top pole
111
having an uniform width portion (a tip portion
111
A) constituting part of the pole portion
200
, and then etching the write gap layer
108
and the bottom pole
107
in a self-aligned manner with use of the tip portion
111
A as a mask.
Enhancing especially the recording density of the recording head among various performances requires miniaturization of the width of the pole portion
200
(magnetic pole width) to the order of submicrons to increase the track density at the recording medium. For this purpose, the magnetic pole width is preferably made uniform with high precision throughout the pole portion
200
. This is because a magnetic pole having a partially greater width causes a side erase, i.e. causing data to be written not only in a track area intended for writing but also in the adjacent track areas, thereby overwriting and erasing information already written in the adjacent track areas.
However, although such miniaturization of the magnetic pole width to the order of submicrons is required, it has been difficult to form the tip portion
111
A of the top pole
111
used as a mask for forming the pole portion
200
with high precision because of the reasons below.
When, for example, the thin film coil
109
is first formed on a planar layer lying thereunder (such as the write gap layer
108
) and covered with the insulating layer
110
, a hill portion (hereinafter referred to also as an “apex portion”) of photoresist is formed on the planar underlying layer. The surface of the apex portion in the vicinity of an edge thereof is fluidized by a heat treatment performed on the photoresist to fill in each gap between turns of the thin film coil
109
, and therefore this surface is formed as a rounded slope. When the top pole
111
formed of a plated film pattern is provided in a region having an irregular structure resulting from the apex portion and the like, light is reflected horizontally or obliquely from the underlying slope when an exposure process is performed on the photoresist film formed in the irregular structure region during a process of forming a framework (frame pattern) used for forming the plated film pattern. Such reflected light decreases the precision of forming the frame pattern because the reflected light increases or decreases the region in the photoresist film exposed to light. This results in a similar decrease in precision of forming the tip portion
111
A of the top pole
111
having a very small width.
Such a decrease in precision of forming the top pole
111
is determined based on, for example, the height of the apex portion from the underlying layer, and the decrease becomes more prominent as an apex angle &agr;
1
, which is one of the factors determining the performance of the recording head, is increased. The apex angle &agr;
1
is an angle between the tangent line to the slope of the insulating layer
110
covering the thin film coil
109
located closer to the air bearing surface
120
side and the surface of the planar underlying layer (write gap layer
108
). In the conventional thin film magnetic head shown in FIG.
25
A and
FIG. 25B
, if a sufficient thickness is provided to the part of the insulating layer
110
located over the thin film coil
109
for the sake of electrical isolation between the thin film coil
109
and the top pole
111
, the slope of the insulating layer
110
located at the vicinity of its edge becomes steep, resulting in a greater apex angle &agr;
1
.
FIG.
26
A and
FIG. 26B
show an example of an approach for suppressing the decrease in precision of forming the top pole
111
resulting from an increase in the apex angle &agr;
1
. FIG.
26
A and
FIG. 26B
are cross sectional views showing a structure of another conventional thin film magnetic head. In this thin film magnetic head, the insulating layer
110
burying the thin film coil
109
is, for example, composed of two insulating elements (insulating layer portions
110
A and
110
B). The thin film coil
109
is disposed on the insulating layer portion
110
A having a surface formed as a relatively gentle slope in the vicinity of an edge thereof, and the insulating layer portion
110
B is disposed so that its edge on the air bearing surface
120
side is recessed to the edge of the insulating layer portion
110
A on the air bearing surface
120
side. Although such a configuration can reduce an apex angle &agr;
2
as compared to the apex angle in the conventional example shown in FIG.
25
A and
FIG. 25B
(&agr;
2
<&agr;
1
), a step is created in the thickness direction between the insulating layers
110
A and
110
B. Such a step in the insulating layer
110
increases the amount of light reflected in the horizontal direction from the slope of the insulating layer portion
110
B in the stepped portion located on the air bearing surface
120
side during the exposure process for forming the frame pattern, thereby making it difficult to improve the precision of forming the top pole
111
. In addition, the step in the insulating layer
110
causes disturbance in magnetic flux inside the top pole
111
at a portion corresponding to the step, leading to a possible decrease in recording characteristics and the like.
Besides the above-described conventional example, various other specific examples are proposed as an approach of reducing the apex angle to enhance the precision of forming the uniform width portion (tip portion) of the top pole. Japanese Patent Laid-Open Publication
Kenyon & Kenyon
Ometz David L.
SAE Magnetics (H.K. ) Ltd.
LandOfFree
Thin film magnetic head and method of manufacturing the same does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Thin film magnetic head and method of manufacturing the same, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Thin film magnetic head and method of manufacturing the same will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3332777