Semiconductor device manufacturing: process – Having magnetic or ferroelectric component
Reexamination Certificate
2003-01-13
2004-02-17
Chaudhari, Chandra (Department: 2813)
Semiconductor device manufacturing: process
Having magnetic or ferroelectric component
C438S104000, C438S950000
Reexamination Certificate
active
06692977
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for manufacturing a magnetic head for recording information on a magnetic recording medium in the form of a direction of magnetization.
2. Description of the Related Art
In recent years, as computers have become popular, a large quantity of information has become dealt with in daily life. Such information is recorded on a recording medium in the form of a large number of physical marks by an information recording/regeneration apparatus, and the recorded information is regenerated by the information recording/regeneration apparatus reading the marks on the recording medium and generating electrical regeneration signals.
One of the information recording/regeneration apparatus is a hard disk drive (HDD), which is characterized by its large storage capacity and high access speed to information. In general, the HDD comprises a magnetic disk with a surface made of a magnetic material, which constitutes a recording medium, and a magnetic head for recording information in the magnetic disk or regenerating the information recorded in the magnetic disk.
The surface of the magnetic disk is magnetized on a small region (1-bit region) basis, and 1 bit of information is recorded in a 1-bit region in the form of a direction of magnetization.
In general, the magnetic head has a coil shaped like a thin film and is disposed close to the magnetic disk. A current is supplied to the coil in the magnetic head to generate a magnetic field, and the magnetic field is leaked to the outside. The leaked magnetic field causes magnetization of each small region of the magnetic disk, whereby the information is recorded in the magnetic disk.
The surface recording density of the magnetic disk increases from year to year, and accordingly, the magnetic head becomes required to have a higher information recording performance. For example, it is required to increase a recording frequency to further increase an information transfer rate in recording information in the magnetic disk by the magnetic head. In order to attain such an increased transfer rate, a distance between turns of a conductive material constituting the coil in the magnetic head is preferably reduced to reduce a length of a yoke portion, that is, a portion between a recording gap and a connected portion (back gap) between an upper magnetic pole and a lower magnetic pole. Thus, a time lag between the generation of the magnetic field in the coil and the recording of the information in the magnetic disk is reduced, whereby a high frequency recording can be accomplished.
On the coil in the magnetic head, an overcoat layer made of an insulating material containing a metal element, such as alumina (Al
2
O
3
), is formed by sputtering, evaporation or the like to prevent a current leakage.
Now, in a process for manufacturing the magnetic head, a step of forming the overcoat layer made of Al
2
O
3
on the coil by sputtering will be described by referring to FIG.
16
.
Part (a) of
FIG. 16
is a cross-sectional view of a part of the coil in the magnetic head, and part (b) of
FIG. 16
is a cross-sectional view of the same after the overcoat layer made of Al
2
O
3
is formed on the coil shown in part (a) of FIG.
16
.
In a step of forming the coil shown in part (a) of
FIG. 16
, a spiral coil
70
made of Cu is formed on an insulating layer (not shown) by plating.
In a step of forming the coil shown in part (b) of
FIG. 16
, an overcoat layer
81
made of Al
2
O
3
is formed by sputtering on the coil
70
formed in the step shown in part (a) of FIG.
16
.
As described above, if the distance between turns of the copper wire constituting the coil
70
is reduced to reduce the length of the magnetic pole yoke for a higher write rate in the recording of the information in the magnetic disk by the magnetic head, it becomes difficult to completely fill gaps between the turns of the copper wire with Al
2
O
3
, and thus, a void
82
may occur as shown in part (b) of FIG.
16
. If such a void
82
occurs, the coil
70
is corroded (oxidized) and an electrical resistance thereof increases, which may cause an increase of the voltage applied to the coil, increase of heat generation in the coil, for example.
Thus, there is known a technique of applying, to a coil, a photoresist, which is a kind of insulating material which has a higher flowability than the insulating material containing a metal element, such as Al
2
O
3
, and subjecting the photoresist to a thermal treatment or UV (ultraviolet) treatment to cure the photoresist, thereby forming a photoresist layer on the coil.
FIG. 17
is a cross-sectional view of a conventional magnetic head having gaps between turns of the conductive material constituting a coil filled with a photoresist.
The magnetic head shown in
FIG. 17
is a combined magnetic head
32
composed of a regenerating head
10
and a recording head
90
.
The regenerating head
10
of the combined magnetic head
32
comprises an element portion
11
, a regenerating lower shield
12
and a regenerating upper shield
13
disposed to sandwich the element portion
11
from both sides thereof in a thickness direction, and a regenerating gap layer
14
disposed to fill a space between the regenerating lower shield
12
and the regenerating upper shield
13
and sandwich the element portion
11
from both sides thereof in the thickness direction.
The regenerating upper shield
13
of the regenerating head
10
serves also as a lower magnetic pole of a recording head
90
described later. Therefore, in the following description, the lower magnetic pole is assigned the same reference numeral
13
as the regenerating upper shield
13
, and referred to as a lower magnetic pole
13
.
The recording head
90
of the combined magnetic head
32
comprises the lower magnetic pole
13
, a lower tip secondary magnetic pole
91
a
and a back gap
91
b
formed on the lower magnetic pole
13
, an insulating layer
92
also formed on the lower magnetic pole
13
, a lower coil
93
formed on the insulating layer
92
, a lower photoresist coat layer
94
formed to cover the lower coil
93
, a lower overcoat layer
95
formed on the lower photoresist coat layer
94
, and a recording gap layer
96
formed on the lower overcoat layer
95
and the lower tip secondary magnetic pole
91
a
. In addition, the recording head
90
has two layers of coils and further comprises an upper coil
97
formed on the recording gap layer
96
, an upper photoresist coat layer
98
formed on the upper coil
97
, and an upper magnetic pole
99
formed on the upper photoresist coat layer
98
and the recording gap layer
96
.
The lower magnetic pole
13
and the upper magnetic pole
99
are connected to each other by the back gap
91
b
disposed at the center of the lower coil
93
and the upper coil
97
and form a magnetic circuit surrounding the lower coil
93
and the upper coil
97
. The magnetic field generated by the lower coil
93
and the upper coil
97
passes through the lower magnetic pole
13
and the upper magnetic pole
99
and is leaked to the outside via the lower tip secondary magnetic pole
91
a
formed on the lower magnetic pole
13
and the upper magnetic pole
99
. The lower tip secondary magnetic pole
91
a
and the upper magnetic pole
99
each face the magnetic disk, not shown, and the magnetic field leaked to the outside causes the magnetization of each small region of the magnetic disk to be inverted.
With the combined magnetic head
32
shown in
FIG. 17
, as described above, the photoresist, which is a kind of insulating material, has a higher flowability than the insulating materials containing a metal element. Therefore, the spaces between the turns of the conductive material constituting the coil can be filled with the photoresist without any void, and the problem that the electrical resistance of the coil is increased due to the corrosion of the coil can be avoided.
Comparing the photoresist with the insulating material containing a metal element, however, the photoresist ge
Hasegawa Minoru
Ohtsuka Yoshinori
Chaudhari Chandra
Fujitsu Limited
Greer Burns & Crain Ltd.
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