Method of forming a magnetoresistive device

Details Method of forming a magnetoresistive device Method of forming a magnetoresistive device

2001-12-11

2004-12-14

Tugbang, A. Dexter (Department: 3729)

Metal working

Method of mechanical manufacture

Electrical device making

C029S603110, C029S603160, C029S603170, C029S605000, C029S606000, C360S317000, C360S318000, C360S321000, C360S328000, C451S004000, C451S051000

Reexamination Certificate

active

06829819

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates generally to magnetic disk data storage systems, and more particularly to magnetic write transducers and methods for making same, and most specifically to high density magnetic write transducers and methods of making 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 systems
10
of the prior art includes a sealed enclosure
12
, a disk drive motor
14
, a magnetic disk
16
, supported for rotation by a drive spindle S
1
of motor
14
, 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
(which will be described in greater detail with reference to
FIG. 2A
) typically includes an inductive write element with a sensor read element. 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 termed in the art, to “fly” above the magnetic disk
16
. Alternatively, some transducers, known as “contact heads,” ride on the disk surface. Various magnetic “tracks” of information can be written to and/or read from the magnetic disk
16
as the actuator
18
causes the transducer
24
to pivot in a short 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 the intermediate layer
32
, which functions as a first pole, and a second pole
38
disposed above the first pole
32
. The first pole
32
and the second pole
38
are attached to each other by a backgap portion
40
, with these three elements collectively forming a yoke
41
. Above and attached to the first pole
32
at a first pole tip portion
43
, is a first pole pedestal
42
abutting the ABS. In addition, a second pole pedestal
44
is attached to the second pole
38
at a second pole tip portion
45
and aligned with the first pole pedestal
42
. This area including the first and second poles
42
and
44
near the ABS is sometimes referred to as the yoke tip region
46
. A write gap
36
is formed between the first and second pole pedestals
42
and
44
in the yoke tip region
46
. The write gap
36
is filled with a non-magnetic material. This non-magnetic material can be either integral with (as is shown here) or separate from a first insulation layer
47
that lies below the second pole
38
and extends from the yoke tip region
46
to the backgap portion
40
. Also included in write element
28
is a conductive coil
48
, formed of multiple winds
49
, that is positioned within a dielectric medium
50
that lies above the first insulation layer
47
. As is well known to those skilled in the art, these elements operate to magnetically write data on a magnetic medium such as a magnetic disk
16
.
More specifically, an inductive write head such as that shown in
FIGS. 2A-2C
operates by passing a writing current through the conductive coil layer
48
. Because of the magnetic properties of the yoke
41
, a magnetic flux is induced in the yoke
41
by write currents that are 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. A critical parameter of a magnetic write element is a trackwidth of the write element, which determines a magnetic write width (MWW), and therefore drives the recording track density. For example, a narrower trackwidth can result in a narrower MWW and a higher magnetic recording density. The trackwidth is affected by geometries in the yoke tip portion
46
(see
FIG. 2A
) at the ABS. These geometries can be better understood with reference to
FIG. 2B
, a view taken along line
2
B—
2
B of FIG.
2
A.
As can be seen from
FIG. 2B
, the first and second poles
32
,
38
can have different widths W
1
, W
2
respectively in the yoke tip portion
46
(see FIG.
2
A). In the shown configuration, the trackwidth of the write element
28
is defined by the width Wp of the second pole pedestal
44
. As can be better seen from the plan view of
FIG. 2C
taken along line
2
C—
2
C of
FIG. 2B
, the width Wp of the pole pedestals typically is substantially uniform. The gap field of the write element also can be affected by the throat height TH, which is measured from the ABS to the zero throat ZT, as shown in FIG.
2
A. Thus, accurate definition of the both trackwidth and throat height is critical during the fabrication of the write element.
However, the control of trackwidth and throat height can be limited with typical fabrication processes, such as masking and plating at the wafer level. For example, the trackwidth sigma &sgr;
tw
, can be limited to a minimum of 0.07 microns. These problems are further aggravated with increasing topography over which the trackwidth-defining element is formed. Such topography is created by the various heights of other elements that have been formed before the trackwidth-defining element is formed. Greater trackwidth control can be attempted using other processes such as focused ion beam (FIB) milling, however such processes can be expensive. Alternatively, the trackwidth can be defined by the first pole width W
1
. However, such processes can also be expensive, complex, and result in lower production yields.
It can also be very difficult and expensive to form very small trackwidths using typical processes. Therefore, forming a pole pedestal having a trackwidth of about 1.25 microns can be very difficult and expensive, with smaller trackwidths posing even greater challenges. When demand for higher density writing capabilities drives smaller trackwidths, this aspect of fabrication becomes increasingly problematic.
An additional disadvantage of some current write element configurations, such as those shown in
FIGS. 2A-2C
, is a secondary pulse phenomenon that can degrade recording performance. Typically, an intended primary pulse is generated to record a single bit of data. However, due to magnetic saturation at the interface between the second pole pedestal
44
and the second pole tip portion
45
, an unintended second pulse may be produced just after the primary pulse. As linear density increases, in other words, as one attempts to write bits closer together and primary pulses follow one another more closely, this second pulse effect may distort the waveforms of the primary pulses. Such distortions generated by the prior art write elements shown in
FIGS. 2A-2C
when operated at high linear densities makes them unsuitable for high density magnetic recording applications.
Accordingly, what is desired is a wire element that is effective for applications having data densities on the order of 40 Gbits/in
2
with a trackwidth of less than about 1 micron and exhibiting substantially no secondary pulse phenomenon. Further, it is desired to achieve thes

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