Abrading – Precision device or process - or with condition responsive... – Computer controlled
Reexamination Certificate
1999-05-27
2001-02-27
Scherbel, David A. (Department: 3723)
Abrading
Precision device or process - or with condition responsive...
Computer controlled
C451S041000, C451S010000, C029S593000, C029S603160
Reexamination Certificate
active
06193584
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to magnetic recording, more particularly to magnetoresistive (MR) read heads, and most particularly to methods and structures for controlling the stripe height of the MR read heads. Those familiar with the art consider anisotropic magnetoresistive (AMR) read heads, giant magnetoresistive (GMR) read heads, and spin valve read heads to be included in the broader category of MR read heads. Subsequent reference to MR read heads is understood to encompass AMR, GMR, and spin valve devices. Merged inductive write, MR read heads comprise a specific exemplary application in all embodiments described in this invention.
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 drive
10
of the prior art includes a sealed enclosure
12
, a disk drive motor
14
, a magnetic disk
16
, supported for rotation by a spindle S
1
of motor
14
, an actuator
18
and an arm
20
attached to a 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 magnetoresistive read element (shown in FIG.
1
C). 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
. Various magnetic “tracks” of information can be 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 drives is well known to those skilled in the art.
FIG. 1C
depicts a magnetic read/write head
30
including a write element
32
and read element
34
. The edges of the write element
32
and read element
34
also define an air bearing surface ABS in a plane
33
, which flies above the surface of the magnetic disk
16
during operation.
Read element
34
includes a first shield
44
, an intermediate layer
38
which serves as a second shield, and a read sensor
46
located between the first shield
44
and the intermediate layer
38
. The read sensor
46
has a particular stripe height, SH, and a particular location between the first shield
44
and the second shield
38
, both of which are chosen to attain particular read performance. Control of stripe height is important in controlling device resistance, device output amplitude, device bias point and consequently many related measures of performance. MR sensors can be used with a variety of stripe heights, with a typical SH being smaller than about 2 microns, including less than 1 micron. Further, although the read sensor
46
is shown in
FIG. 1C
as a shielded single-element vertical read sensor, the read element
34
can take a variety of forms as is known to those skilled in the art, such as unshielded read sensors. The design and manufacture of magnetoresistive heads, such as read sensor
46
, are well known to those skilled in the art.
Write element
32
is typically an inductive write element including the intermediate layer
38
which serves as a first yoke element or pole, and a second yoke element or pole
36
, defining a write gap
40
therebetween. The first yoke element
38
and second yoke element
36
are configured and arranged relative to each other such that the write gap
40
has a particular throat height, TH. Also included in write element
32
, is a conductive coil
42
that is positioned within a dielectric medium
43
. 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
.
The formation of a read/write head
30
begins with a wafer
50
, as shown in
FIG. 1D
, which includes, formed over a substrate, sets of several layers or films of various materials that form an array of read/write heads (not shown), including the elements of the read/write head
30
that are shown in FIG.
1
C. The wafer
50
is then divided into multiple slider bars
52
such that each slider bar
52
has a first cut surface, or edge,
54
and a second cut surface, or edge,
56
substantially parallel to each other. As can be better seen in
FIG. 1E
, each slider bar
52
may include several read/write heads
60
in series along the bar. For example, a typical slider bar may include about thirty (30) read/write heads
60
. As is shown in
FIG. 1E
, the read/write heads
60
can be of different configuration, however, alternatively each of the write/read heads
60
along the slider bar
52
can be of approximately the same configuration.
As is shown in
FIG. 1E
, the second cut surface
56
is formed such that the read/write heads
60
extend through to the second cut surface
56
. Thus, at the second cut surface
56
, the read/write heads
60
are exposed and therefore available for removing material along the second cut surface
56
in a process termed lapping. Alternatively, the read/write heads
60
can extend to near the second cut surface
56
, without being initially exposed. In such a case, the read/write heads
60
can become exposed and material can be removed therefrom during the lapping process.
The goal of lapping is to remove material from the second cut surface
56
, which defines a lapping plane L, to form the ABS (also shown in
FIG. 1C
) of each of the read/write heads
60
in the plane
33
. More particularly, it is the objective of the lapping process to define the ABS at a precise predetermined distance from the upper edge
64
of the read sensor
46
where the upper edge
64
is defined by wafer processes. In this way, the stripe As height SH of the read sensor
46
(shown in
FIG. 1C
) is defined substantially orthogonal to the lapping plane L, and the throat height TH is similarly defined substantially orthogonal to the lapping plane L. After lapping, the read/write heads are then each cut from the slider bar to form individual read/write heads.
FIG. 1F
shows a typical lapping machine
70
. The slider bar
52
is held along the first cut surface
54
by a jig
72
. In turn, the jig
72
is contacted by pistons
74
at various bending points
76
along the length of the jig
72
. Pistons
74
may be, for example, dual action air cylinders, and are configured to deflect the jig
72
at the bending points
76
by a particular amount. To obtain this particular amount, a controller
78
is used to regulate the operation of the pistons
74
. The slider bar
52
is further oriented such that the second cut surface
56
lies substantially parallel to an upper surface
80
of a lapping plate
82
. During lapping, an abrasive material, for example a diamond slurry, is introduced between the second cut surface
56
of the slider bar
52
and the upper surface
80
of the lapping plate
82
. When the second cut surface
56
is brought into contact or near-contact with the upper surface
80
, the slider bar
52
and the lapping plate
82
are moved relative to each other within the plane defined by the second cut surface
56
and the upper surface
80
. This movement, along with the forces acting to press together the upper surface
80
and the second cut surface
56
and with the abrasive material placed therebetween, acts to abrasively lap the second cut surface
56
and thereby the read/write heads
60
.
Because of the critical nature of the stripe height, SH, it is important to end the lapping process at the particular point which attains the correct stripe height. While lapping times, lapping pressures, and other lapping parameters could be standardized for particular types of slider bars
52
, such a method can be ineffective due to fabrication variations such as in the deposition of materials of the read/write heads
60
, or the wafer cut locations relative to the read/write heads. More particularly, some fabrication variations may exist
Crue, Jr. Billy W.
Harnischfeger Michael T.
Macchioni Curtis V.
Plewes Steven J.
Rudy Steven C.
Hickman Coleman & Hughes LLP
Nguyen George
Read-Rite Corporation
Scherbel David A.
LandOfFree
Apparatus and method of device stripe height control does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus and method of device stripe height control, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus and method of device stripe height control will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2579220