Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
1999-08-13
2002-04-09
Renner, Craig A. (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Core
C360S123090
Reexamination Certificate
active
06369983
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to magnetic recording technology and more particularly to a method and system for providing a glue layer and seed layer for the coil of a write head.
BACKGROUND OF THE INVENTION
Magnetic data is typically stored on a magnetic recording medium, such as a disk, using a conventional write head. The conventional write head may be a separate head, but is typically part of a conventional merged head.
FIG. 1A
depicts a conventional merged head
10
. The conventional merged head
10
typically includes a read head
11
for reading magnetic data and a conventional write head
19
. The conventional read head includes a first shield
12
, first and second gaps
14
and
18
, respectively, and a magnetoresistive sensor
16
. The magnetoresistive sensor
16
is typically a giant magnetoresistance sensor, such as a spin valve. The conventional read head
11
also includes a first pole/second shield
20
(“first pole”). Although used in writing, the first pole
20
also acts as a shield for the conventional read head
11
.
The conventional write head
19
is typically an inductive head, including the first pole
20
and a second pole
26
. The second pole
26
is typically grown on a seed layer
24
. The first pole
20
and second pole
26
are separated by a write gap
22
. The write head also typically includes one or more conventional coils
30
which are used to carry current. Two conventional coils
30
are depicted in FIG.
1
A. When energized by the current driven through the conventional coils
30
, the first and second poles
20
and
26
generate a magnetic field in the write gap. When brought into proximity with the disk or other recording media, the magnetic field writes data to the disk.
FIG. 1B
depicts the coils
30
and the surrounding part of the conventional write head
19
. The conventional coils
30
include two conventional coils,
30
-
1
and
30
-
2
, having six turns each. The conventional coils
30
are insulated from the first pole
20
, the second pole
26
, and each other by conventional insulating layers
32
,
40
, and
42
. Each conventional coil
30
-
1
and
30
-
2
includes a conventional conductive layer
38
and
48
, respectively, that are typically made of copper. Each of the copper layers
38
and
48
is grown on a conventional seed layer
36
and
46
, respectively. The conventional seed layers
36
and
46
are also typically made of copper. The conventional seed layers
36
and
46
are grown on conventional glue layers
34
and
44
, respectively. The conventional glue layers
34
and
44
promote adhesion between the corresponding conventional coil
30
-
1
and
30
-
2
and the insulating layers
32
and
40
, respectively. The conventional glue layers
34
and
44
are typically composed of titanium. Thus, the conventional seed layers
36
and
46
and the conventional glue layers
34
and
44
may carry some current driven through the conventional coils
30
-
1
and
30
-
2
, respectively.
In order to form the conventional coils
30
for the write head
19
, photolithography is typically used.
FIG. 2
depicts a conventional method
50
for forming one of the conventional coils
30
. Although the method
50
can be used for either conventional coil
30
-
1
or
30
-
2
,
FIG. 2
will be explained in the context of providing the first conventional coil
30
-
1
.
FIGS. 3A through 3D
depict a portion of the conventional write head
19
during formation of the conventional coil
30
-
1
. Referring now to FIGS.
2
and
3
A-
3
D, the conventional glue layer
34
is provided on the conventional insulating layer
32
, via step
52
. Thus, step
52
typically includes depositing a layer of Ti on the conventional insulating layer
32
. The conventional glue layer
34
promotes adhesion to the insulating layer
32
. The conventional seed layer
36
, which is typically made of Cu, is then provided on the conventional glue layer
34
, via step
54
.
FIG. 3A
depicts the conventional insulating layer
32
, conventional glue layer
34
, and conventional seed layer
36
after step
54
is performed. A resist structure is provided on the conventional seed layer
36
, via step
56
.
FIG. 3B
depicts a portion of the conventional write head
19
after the resist structure
37
is provided. The lines in the resist structure
37
cover the portions of the conventional seed layer
36
above which an insulator will be used to separate turns of the conventional coil
30
-
1
. The resist structure
37
thus includes apertures in areas in which the conventional coil
30
-
1
will be formed. The conventional coil
30
-
1
is then deposited, via step
58
. Step
58
is typically performed by plating the copper layer
38
onto the conventional seed layer
36
. The resist structure
37
is then stripped, via step
60
.
FIG. 3C
depicts the conventional coil
30
-
1
including copper layer
38
. The portions of the conventional seed layer
36
and the conventional glue layer
34
between the turns of the conventional copper coil
38
are then wet etched, via step
62
. The wet etch ensures that the turns of the conventional coils
30
-
1
and
30
-
2
are insulated from each other.
FIG. 3D
depicts the conventional coil
30
-
1
after the conventional seed layer
36
and conventional copper layer
34
have been etched.
One of ordinary skill in the art will readily realize that the trend in magnetic recording is toward higher data transfer rates. Reducing the length of the conventional write head
11
, especially the length of the poles
20
and
26
, can reduce the head inductance. Thus, the flux rise time is decreased and the data transfer rate can be increased. In order to reduce the length of the poles
20
and
26
, either the turns of the coils
30
are more densely packed or the ability of the coils to carry increased current is increased. Thus, the pitch of the coils
30
is desired to be decreased and the aspect ratio of the coils
30
is desired to be increased. The aspect ratio is the ratio of the height of a turn of the coils
30
to the width along the length of the poles
20
or
26
of a turn of the coils
30
. The pitch is the width of the coil plus the distance between turns of the coils
30
. The pitch or aspect ratio is changed because decreasing the total cross-sectional area of the coils
30
(height multiplied by width) results in excessive electrical resistance and, therefore, excessive heating.
Although it would be desirable to more densely pack the turns of the coils
30
, use of the conventional seed layers
36
and
46
and the conventional glue layers
34
and
44
limit the ability to reduce the length of the poles
20
and
26
. Conventional photolithography results in the resist structure
37
having lines that are separated by a particular width, currently approximately 0.4 &mgr;m. Conventional photolithography may be limited in the width provided by reflective effects. For example the swing curve effect and resist notching alter the resist pattern due to light reflected off of layers beneath the resist structure
37
. Thus, portions of the copper layers
28
and
48
are separated by a given distance prior to etching of the conventional seed layer
36
or
46
and the conventional glue layer
34
or
44
. The wet etch which is used to etch the conventional seed layers
36
and
46
and the conventional glue layers
34
and
44
limits the pitch of the coils
30
. The wet etch of step
62
etches not only the conventional seed layer
36
and
46
and conventional glue layers
34
and
44
, but also etches the copper layers
38
and
48
. The wet etch is also isotropic. Thus, both the height and width of the copper layers
38
and
48
are reduced by the wet etch. This reduction in the height and width of the copper layers
38
and
48
can be seen in
FIGS. 3C and 3D
. For example, if the seed layer
36
or
46
is approximately 0.1 &mgr;m thick, a wet etch which etches through the conventional seed layer
36
or
46
may reduce the height of the copper layer
38
or
48
by 0.1 &mgr
Read-Rite Corporation
Renner Craig A.
Sawyer Law Group LLP
LandOfFree
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