Dynamic magnetic information storage or retrieval – Head – Coil
Reexamination Certificate
1999-05-14
2002-02-19
Heinz, A. J. (Department: 2165)
Dynamic magnetic information storage or retrieval
Head
Coil
C360S125330
Reexamination Certificate
active
06349014
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to magnetic data storage systems, more particularly to magnetoresistive read heads, and most particularly to structures incorporating an insulating barrier, as well as methods for making the same.
Magnetic disk drives are used to store and retrieve data for digital electronic apparatuses such as computers. In
FIGS. 1A and 1B
, a magnetic disk data storage system
10
includes a sealed enclosure
12
, a disk drive motor
14
, and a magnetic disk, or media,
16
supported for rotation by a drive spindle S
1
of motor
14
. Also included are an actuator
18
and an arm
20
attached to an actuator spindle S
2
of actuator
18
. A suspension
22
is coupled at one end to the arm
20
, and at its other end to a read/write head or transducer
24
. The transducer
24
typically includes an inductive write element with a sensor read element (which will be described in greater detail with reference to FIG.
2
A). As the motor
14
rotates the magnetic disk
16
, as indicated by the arrow R, an air bearing is formed under the transducer
24
causing it to lift slightly off of the surface of the magnetic disk
16
, or, as it is sometimes termed in the art, to “fly” above the magnetic disk
16
. Alternatively, some transducers, known as “contact heads,” ride on the disk surface. Data bits can be read along a magnetic “track” as the magnetic disk
16
rotates. Also, information from various tracks can be read from the magnetic disk
16
as the actuator
18
causes the transducer
24
to pivot in an arc as indicated by the arrows P. The design and manufacture of magnetic disk data storage systems is well known to those skilled in the art.
FIG. 2A
depicts a magnetic read/write head
24
including a substrate
25
above which a read element
26
and a write element
28
are disposed. Edges of the read element
26
and write element
28
also define an air bearing surface ABS, in a plane
29
, which can be aligned to face the surface of the magnetic disk
16
(see FIGS.
1
A and
1
B). The read element
26
includes a first shield
30
, an intermediate layer
32
, which functions as a second shield, and a read sensor
34
that is located within a dielectric medium
35
between the first shield
30
and the second shield
32
. The most common type of read sensor
34
used in the read/write head
24
is the magnetoresistive (AMR or GMR) sensor which is used to detect magnetic field signals from a magnetic medium through changing resistance in the read sensor.
The write element
28
is typically an inductive write element which includes a first pole
38
and the intermediate layer
32
, which functions as a second pole. A second pole pedestal
42
is connected to a second pole tip portion
45
of the second pole. The first pole
38
and the second pole
32
are attached to each other by a backgap portion
40
, with these three elements collectively forming a yoke
41
with the second pole pedestal
42
. The area around the first pole tip portion
43
and a second pole tip portion
45
near the ABS is sometimes referred to as the yoke tip region
46
. A write gap
36
is formed between the first pole
38
and the second pole pedestal
42
in the yoke tip region
46
. The write gap
36
is filled with a non-magnetic electrically insulating material that forms a write gap material layer
37
. This non-magnetic material can be either integral with (as is shown here) or separate from a first insulation layer
47
that lies between the first pole
38
and the second pole
32
, and extends from the yoke tip region
46
to the backgap portion
40
.
Also included in write element
28
is a conductive coil layer
48
, formed of multiple winds
49
. The conductive coil
48
is positioned within a coil insulation layer
50
that lies below the first insulation layer
47
. The first insulation layer
47
thereby electrically insulates the coil layer
48
from the second pole
32
, while the coil insulation layer
50
electrically insulates the winds
49
from each other and from the second pole
38
. In some prior art fabrication methods, the formation of the coil insulation layer includes a thermal curing of an electrically insulating material, such as photoresistive material. However, when this process is performed after the formation of the read sensor, the magnetic properties of the read sensor can be permanently and undesirably altered. Thus, the formation of the coil layer
48
and the coil insulation layer
50
before formation of the read sensor can help to avoid such damage to the read sensor during fabrication.
More specifically, an inductive write head such as that shown in
FIG. 2A
operates by passing a writing current through the conductive coil layer
48
. Because of the magnetic properties of the yoke
41
, a magnetic flux can be induced in the first and second poles
38
,
32
by a write current passed through the coil layer
48
. The write gap
36
allows the magnetic flux to fringe out from the yoke
41
(thus forming a fringing gap field) and to cross a magnetic recording medium that is placed near the ABS.
As a current is passed through, the coil layer
48
can increase in temperature. Heat can then transfer to other components of the read/write head
24
, for example the read sensor
34
. With sufficiently high heating of the read sensor
34
, the magnetic properties of the read sensor
34
can undesirably change, thereby adversely affecting the read capabilities during such heating. Further, this heating can thermally damage the read sensor
34
, including undesirably permanently altering the read capabilities of the read sensor.
A critical parameter of a magnetic write element is a trackwidth of the write element, which defines track density. For example, a narrower trackwidth can result in a higher magnetic recording density. The trackwidth is defined by geometries in the yoke tip portion
46
at the ABS. These geometries can be better understood with reference to FIG.
2
B. As can be seen from this view, the first and second poles
38
,
32
can be wider in the yoke tip portion
46
(see
FIG. 2A
) than the second pole pedestal
42
. In the shown configuration, the trackwidth of the write element
28
is defined by the width W
P
2
P
of the second pole pedestal
42
. However, control of the second pole pedestal width W
P
2
P
can be limited by typical fabrication processes. More specifically, these dimensions can be difficult to control when the second pole pedestal
42
is formed over a substantially non-planar topography that includes the elements that were formed before the second pole pedestal
42
. For example, the definition of the second pole pedestal width W
P
2
P
, for example including photoresistive material (“photoresist”) deposition and etching, can be decreasingly reliable and precise with increasing topography. When demand for higher density writing capabilities drives smaller trackwidths, this aspect of fabrication becomes increasingly problematic. For example, the width W
P
2
P
can be limited to a minimum of about 0.4 microns for 35 Gb/in
2
magnetic recording.
Thus, what is desired is a write element that is magnetically and thermally more efficient, and that has minimal adverse impact on a read sensor when combined with a read element to form a read/write head. Further, it is desired that fabrication of such a write element and read/write head be inexpensive, quick, and simple.
SUMMARY OF THE INVENTION
The present invention provides a magnetic recording device and method for making the same that provides high recording performance. More specifically, a write element having high thermal and magnetic efficiency is provided.
In an embodiment of the present invention a device for exchanging data with a magnetic medium includes a substrate and a first pole formed of ferromagnetic material and disposed above the substrate. A second pole formed of ferromagnetic material is disposed above the substrate. The first and second pole each have an edge that forms an air bearing surface. The device also includes a c
Apparao Renuka
Crue, Jr. Billy W.
Seymour Mark
Shi Zhupei
Young Ken
Carr & Ferrell LLP
Hayden Robert D.
Heinz A. J.
Read-Rite Corporation
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