U.S. patent application number 11/700474 was filed with the patent office on 2008-10-16 for non-magnetic contact enhancement feature.
This patent application is currently assigned to Seagate Technology LLC. Invention is credited to Lars H. Ahlen, Ladislav R. Pust, Edwin F. Rejda, David C. Seets, Dian Song, Lance E. Stover, Feng Y. Wang.
Application Number | 20080253021 11/700474 |
Document ID | / |
Family ID | 39853471 |
Filed Date | 2008-10-16 |
United States Patent
Application |
20080253021 |
Kind Code |
A1 |
Pust; Ladislav R. ; et
al. |
October 16, 2008 |
Non-magnetic contact enhancement feature
Abstract
A transducer having an external contact surface includes a
writer and a contact member. The writer has a portion extendable
beyond the external contact surface. The contact member surrounds
at least a portion of the extendable writer portion.
Inventors: |
Pust; Ladislav R.; (Savage,
MN) ; Ahlen; Lars H.; (Bloomington, MN) ;
Rejda; Edwin F.; (Bloomington, MN) ; Seets; David
C.; (Shorewood, MN) ; Stover; Lance E.; (Eden
Prairie, MN) ; Song; Dian; (Eden Prairie, MN)
; Wang; Feng Y.; (Eden Prairie, MN) |
Correspondence
Address: |
KINNEY & LANGE, P.A.
312 SOUTH 3RD STREET, THE KINNEY & LANGE BUILDING
MINNEAPOLIS
MN
55415
US
|
Assignee: |
Seagate Technology LLC
Scotts Valley
CA
|
Family ID: |
39853471 |
Appl. No.: |
11/700474 |
Filed: |
April 12, 2007 |
Current U.S.
Class: |
360/122 ;
428/814 |
Current CPC
Class: |
G11B 5/40 20130101; G11B
5/3133 20130101; G11B 5/6064 20130101; G11B 5/3106 20130101; G11B
5/3136 20130101; G11B 5/3169 20130101; G11B 5/6076 20130101; Y10T
428/1164 20150115; Y10T 29/49032 20150115; G11B 5/1278
20130101 |
Class at
Publication: |
360/122 ;
428/814; 428/814 |
International
Class: |
G11B 5/187 20060101
G11B005/187; G11B 5/127 20060101 G11B005/127; G11B 5/33 20060101
G11B005/33 |
Claims
1. A transducer having an external contact surface, the transducer
comprising: a writer having a portion extendable beyond the
external contact surface; and a contact member surrounding at least
a portion of the extendable writer portion.
2. The transducer of claim 1, wherein the extendable writer portion
has a coefficient of thermal expansion and the contact member has a
coefficient of thermal expansion, and wherein the coefficient of
thermal expansion of the contact member is approximately equal to
the coefficient of thermal expansion of the extendable writer
portion.
3. The transducer of claim 1, wherein the extendable writer portion
has an external surface area and the contact member has an external
surface area, wherein the external surface area of the contact
member is larger than the external surface area of the extendable
writer portion.
4. The transducer of claim 1, wherein the contact member has a
height approximately equal to a height of the extendable writer
portion.
5. The transducer of claim 1, and further comprising a write coil
structure, wherein the contact member is formed at an end of the
write coil structure.
6. The transducer of claim 5, and further comprising alumina
deposited on the write coil structure, wherein the contact member
is formed from the alumina.
7. The transducer of claim 5, and further comprising a write coil
front shield, wherein the contact member is formed from the write
coil front shield.
8. The transducer of claim 5, and further comprising a write coil
refill within the write coil structure, wherein the contact member
is formed from the write coil refill.
9. The transducer of claim 1, wherein the contact member is formed
over the extendable writer portion.
10. The transducer of claim 1, and further comprising a protective
material positioned proximate the extendable writer portion.
11. The transducer of claim 10, wherein the protective material is
selected from the group consisting of: SiC, Ta, and Cr.
12. The transducer of claim 1, and further comprising a corrosion
protection layer positioned proximate the extendable writer
portion.
13. The transducer of claim 12, wherein the corrosion protection
layer is selected from the group consisting of: a self-assembled
monolayer film and a SeaWax-type head lubricant.
14. A transducing device having a storage interface surface, the
device comprising: a writer having a pole tip region proximate the
storage interface surface; a write coil positioned around the pole
tip region, the write coil having a plurality of write coil layers;
and a contact feature proximate to, and aligned with, the pole tip
region, the contact feature being formed with respect to the pole
tip region.
15. The device of claim 14, and further comprising alumina
deposited on the write coil, wherein the contact feature is formed
from the alumina.
16. The device of claim 14, wherein the write coil comprises a
front shield, and wherein the contact feature is formed from the
write coil front shield.
17. The device of claim 14, and further comprising a write coil
refill positioned between the write coil layers, wherein the
contact feature is formed from the write coil refill.
18. The device of claim 14, wherein the contact feature is
deposited around the pole tip region.
19. The device of claim 14, wherein the contact feature is formed
of a material selected from the group consisting of: Diamond-Like
Carbon and Cr.
20. The device of claim 14, wherein the pole tip region has a
coefficient of thermal expansion and the contact feature has a
coefficient of thermal expansion, and wherein the coefficient of
thermal expansion of the contact feature is approximately equal to
the coefficient of thermal expansion of the pole tip region.
21. The device of claim 12, and further comprising a protective
material positioned proximate the pole tip region.
22. The device of claim 12, and further comprising a corrosion
protection layer positioned proximate the pole tip region.
23. A transducer having a storage interface surface, the transducer
comprising: a plurality of thin film layers; and a contact
enhancement feature adjacent at least one of the plurality of thin
film layers.
24. The transducer of claim 23, wherein the plurality of thin film
layers has a coefficient of thermal expansion and the contact
enhancement feature has a coefficient of thermal expansion, and
wherein the coefficient of thermal expansion of the contact
enhancement feature is approximately equal to the coefficient of
thermal expansion of the plurality of thin film layers.
25. The transducer of claim 23, wherein the plurality of thin film
layers comprises a pole tip region, wherein the pole tip region has
a surface area and the contact enhancement feature has a surface
area, and wherein the surface area of the contact enhancement
feature is larger than the surface area of the pole tip region.
26. The transducer of claim 23, wherein the contact enhancement
feature is formed over the pole tip region.
27. The transducer of claim 23, and further comprising a protective
material positioned proximate the pole tip region.
28. The transducer of claim 27, wherein the protective material is
selected from the group consisting of: SiC, Ta, Cr, a
self-assembled monolayer film, and a SeaWax-type head
lubricant.
29. The transducer of claim 23, and further comprising a corrosion
protection layer positioned proximate the pole tip region.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates generally to a magnetic head
that includes a contact enhancement feature. In particular, the
present invention relates to a magnetic head having a wide
head-to-media contact surface.
[0002] Magnetic data storage and retrieval systems store and
retrieve information on magnetic media. A magnetic head is
supported relative to a magnetic media surface by a slider. During
operation, the disc is rotated by a spindle motor which creates
airflow along a storage interface surface (SIS) of the slider from
a leading edge to a trailing edge of the slider. Airflow along the
SIS of the slider creates a hydrodynamic lifting force so the head
of the slider essentially flies above the surface of the magnetic
media. The distance between the slider and the magnetic media is
known as the fly height.
[0003] In a magnetic data storage and retrieval system, a magnetic
head typically includes a writer portion for storing
magnetically-encoded information on a magnetic media and a reader
portion for retrieving the magnetically-encoded information from
the magnetic media. To write data to the magnetic media, an
electrical current is caused to flow through a conductive write
coil to induce a magnetic field in a write pole. By reversing the
direction of the current through the write coil, the polarity of
the data written to the magnetic media is also reversed.
[0004] During operation of the magnetic data storage and retrieval
system, the magnetic head is positioned in close proximity to the
magnetic media. The distance between the magnetic head and the
media is preferably small enough to allow for writing to and
reading from the magnetic media with a large areal density, and
great enough to prevent contact between the magnetic media and the
magnetic head. Performance of the magnetic head depends primarily
upon head-media spacing (HMS). High density recording preferably
requires a small HMS and a low fly height. Prior to using each
magnetic head, there are small variations in fly height that must
be accounted for due to changing operating conditions and
head-to-head variations.
[0005] As the need for data storage increases, the areal bit
density of magnetic media also increases. In order to utilize the
increased areal bit density of high density magnetic discs, it is
necessary to reduce the fly height between the slider and the
magnetic media surface. However, as fly height decreases, there is
an increased possibility of unintentional contact between the
magnetic head and the magnetic media. Extensive contact between the
head and the magnetic media can damage the head and lead to loss of
data. Thus, the fly clearance must be measured for each magnetic
head by a controlled measurable non-destructive head-media contact
so that the proper algorithm for operating the heater is used for
each magnetic head.
[0006] In operation, the layers of the head, which include both
metallic and insulating layers, all have different mechanical and
chemical properties than the substrate. The differences in
properties affect several aspects of the head, including pole tip
protrusion of the metallic layers of the head with respect to the
substrate at the SIS of the head. Two components of the pole tip
protrusion effect exist, thermal pole tip protrusion and
current-induced pole tip protrusion. Thermal pole tip protrusion
arises from isothermal (global) temperature changes in the head
during drive operation. Current-induced pole tip protrusion results
from localized heating during application of currents to the write
coil and the resultant heat dissipation into the surrounding
components of the head. The pole tip protrusion must be accounted
for when determining the proper fly height between the slider and
the surface of the magnetic media.
[0007] The head-media contact is typically detected by a signal
that changes sharply when the head mechanically contacts a lube
layer of the magnetic media. For example, the signal could be
.DELTA.PES (position error signal). In the .DELTA.PES method of
detecting contact, when a head at skew contacts a lubricant layer
on the media, it is dragged off-track more than when only flying.
To compensate for this off-track drag force, a larger .DELTA.PES is
generated by a positioning system to keep the head on track.
Another method of detecting contact between the head and the
magnetic media is acoustic emission (AE) detection. AE detection
utilizes the ultrasound made when a head and magnetic media come
into contact. To use .DELTA.PES or AE, the surface area of the
head-media contact must be large enough so that when the thermally
protruded magnetic head hits the lube layer of the magnetic media,
the magnetic head component protruding most at the storage
interface surface does not penetrate past the lube layer and start
burnishing on the hard media surface, destroying the protective
magnetic head layer.
[0008] Fly height control is particularly problematic in
high-density magnetic data storage and retrieval systems that use
perpendicular writers. In perpendicular writer designs, the return
poles are positioned further away from the primary write pole when
compared to longitudinal writer designs. During thermally induced
contact, only a small region close to the primary write pole
comes,into contact with the magnetic media. Consequently, the
contact area is much smaller for perpendicular writer designs. Both
.DELTA.PES and AE depend on signals that are proportional to the
surface area of the contact between the head and the magnetic
media. Thus, the heads of perpendicular writers result in a smaller
signal for use in contact detection by AE or .DELTA.PES. Additional
factors, such as the speed at which the magnetic media revolves,
the storage interface surface topology, and air bearing
pressurization, can also reduce the contact signal.
[0009] Although the feature of the magnetic head that contacts the
disc must have a large surface area to control clearance, due to
process variations, the primary write pole does not always end up
as the closest point to the disc for all magnetic heads. This is
needed to minimize the HMS between the writer and the disc. Due to
variations in the relative alignment between the primary write pole
and the contact point, a significant percentage of magnetic heads
have a recessed write pole, causing increased HMS of the primary
write pole. Therefore, there is a need for both enhanced contact
detection between the magnetic head and disc of a magnetic data
storage and retrieval system and for improved alignment between the
write pole and the large head-media contact surface.
BRIEF SUMMARY OF THE INVENTION
[0010] In one aspect, the invention is a transducer having an
external contact surface and includes a writer and a contact
member. The writer has a portion extendable beyond the external
contact surface. The contact member surrounds at least a portion of
the extendable writer portion.
[0011] In another aspect, the invention is a transducing device
having a storage interface surface and includes a writer, a write
coil, and a contact enhancement feature. The writer has a pole tip
region proximate the storage interface surface. The write coil is
positioned around the pole tip region and has a plurality of write
coil layers. The contact enhancement feature is proximate to and
aligned with the pole tip region.
[0012] In another aspect, the invention is a transducer having a
storage interface surface and includes a plurality of thin film
layers and a contact enhancement feature. The contact enhancement
feature is adjacent at least one of the plurality of thin film
layers.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a top view of a representative magnetic head
having a contact enhancement feature.
[0014] FIG. 2A is a sectional view of a first embodiment of a
magnetic head having a contact enhancement feature prior to
lapping.
[0015] FIG. 2B is a sectional view of the first embodiment of a
magnetic head having a contact enhancement feature after
lapping.
[0016] FIG. 3A is a sectional view of a second embodiment of the
contact enhancement feature of the magnetic head prior to
lapping.
[0017] FIG. 3B is a sectional view of the second embodiment of the
contact enhancement feature of the magnetic head after lapping.
[0018] FIG. 4A is a sectional view of a third embodiment of the
contact enhancement feature of the magnetic head prior to
lapping.
[0019] FIG. 4B is a sectional view of the third embodiment of the
contact enhancement feature of the magnetic head after lapping.
[0020] FIG. 5A is a sectional view of a fourth embodiment of the
contact enhancement feature of the magnetic head prior to
lapping.
[0021] FIG. 5B is a sectional view of the fourth embodiment of the
contact enhancement feature of the magnetic head during
lapping.
[0022] FIG. 5C is a sectional view of the fourth embodiment of the
contact enhancement feature of the magnetic head after lapping.
[0023] FIG. 6A is a sectional view of a write pole of a magnetic
head after lapping but prior to a first controlled head-media
contact.
[0024] FIG. 6B is a sectional view of the write pole of the
magnetic head shown in FIG. 6A after lapping and after the first
controlled head-media contact.
[0025] FIG. 7 is a storage interface surface view of a fifth
embodiment of a contact enhancement feature surrounding the write
pole shown in FIGS. 6A and 6B.
DETAILED DESCRIPTION
[0026] FIG. 1 is a top view of magnetic head 10 having contact
enhancement feature 12, write pole tip 14, and substrate 16.
Contact enhancement feature 12 serves to increase the head-media
contact area of write pole tip 14 and is thus positioned proximate
write pole tip 14. The head-media contact is the first contact
point between magnetic head 10 and media M (shown in FIGS. 2A-4B).
Contact enhancement feature 12 creates a head-media contact surface
that is wide enough to detect contact between magnetic head 10 and
media M before write pole tip 14 penetrates the lube layer of media
M and write pole tip 14 or another component is destroyed. As the
head-media contact surface increases in width W, the chances of
write pole tip 14 dipping past the lube layer onto the hard media
surface of media M and burnishing write pole tip 14 decreases.
[0027] To adequately protect write pole tip 14, contact enhancement
feature 12 has a much larger surface area than write pole tip 14.
The surface area of contact enhancement feature 12 is sized such
that .DELTA.PES or AE contact detection methods can be effectively
used. Because contact enhancement feature 12 has a much larger
surface area than write pole tip 14, a signal generated by contact
between contact enhancement feature 12 and media M will be much
larger than a signal generated by contact between write pole tip 14
and media M. Thus, the fly height of magnetic head 10 can be
adjusted before any damage to write pole tip 14. In one embodiment,
contact enhancement feature 12 has a surface area of about 20
.mu.m.sup.2.
[0028] In operation, contact enhancement feature 12 has a height
substantially equal to the height of write pole tip 14 and is used
to indicate when write pole tip 14 is in danger of contacting media
M. Because contact enhancement feature 12 and write pole tip 14
have substantially the same height, when contact enhancement
feature 12 contacts media M, write pole tip 14 is also in close
proximity to media M, indicating that the fly height of magnetic
head 10 should be adjusted to avoid burnishing write pole tip 14.
Therefore, it is important that write pole tip 14 and contact
enhancement feature 12 are positioned in close proximity to one
another and have essentially the same height. In one embodiment,
contact enhancement feature 12 is positioned about 10 microns
(.mu.m) from write pole tip 14 and the difference in height between
write pole tip 14 and contact enhancement feature 12 is less than 1
nanometer (nm).
[0029] Contact enhancement feature 12 can be formed by a variety of
designs, depending on acceptable trade-offs between the complexity
of the manufacturing process and the robustness of the design.
Currently, contact enhancement feature 12 is formed by building
additional larger metallic components at the storage interface
surface (SIS) near write pole tip 14 or by using other functioning
components of magnetic head 10. For example, magnetic front shields
or return poles can be used as contact enhancement feature 12.
However, certain writer designs do not include a front shield or a
return pole, in which case a non-magnetic contact enhancement
feature is more desirable so that the contact enhancement feature
structure does not interfere with the magnetic operations of the
magnetic head. Alternatively, contact enhancement feature 12 has
also been built specifically to provide the needed wide and flat
head-media contact surface. The general principle of the contact
enhancement feature is that in operation, heat will cause write
pole tip 14 to expand in the fly height direction. Thus, regardless
of how contact enhancement feature 12 is formed, contact
enhancement feature 12 is typically built from a material having a
coefficient of thermal expansion similar to write pole tip 14 so
that it will expand at the same rate as write pole tip 14 and be
able to indicate when the fly height of magnetic head 10 needs to
be adjusted, protecting write pole tip 14 from coming into contact
with media M.
[0030] FIGS. 2A and 2B are sectional views of a first embodiment of
magnetic head 10 having contact enhancement feature 12A and writer
18 prior to lapping and after lapping, respectively. Writer 18
generally includes return pole 20, write pole 22, write pole tip 14
located at an end of write pole 22 at the SIS, yoke 24, write coil
26 (shown as write coil turns 26A, 26B, 26C, 26D, 26E, and 26F),
and insulator 28. Although magnetic head 10 is shown having one
return pole 20, writer 18 may have two return poles or no return
pole without departing from the intended scope of the
invention.
[0031] Return pole 20 and write pole 22 extend from the SIS and are
connected to each other distal from the SIS. Yoke 24 is formed on
write pole 22 but does not extend the full length of write pole 22.
Insulator 28 separates return pole 20, write pole 22, and write
coil 26 from each other. Return pole 20 and yoke 24 are formed from
metallic ferromagnetic materials. Preferably, each of these
components is formed from an alloy composed primarily of Fe, Ni,
and/or Co which typically has a large CTE.
[0032] As shown in FIGS. 2A and 2B, write coil 26 has coil turns
26A, 26B, 26C, 26D, 26E, 26F. Write coil turns 26A, 26B, 26C, 26D,
26E, 26F wrap around write pole 22 such that the flow of electrical
current through conductive write coil 26 generates a magnetic flux
at write pole tip 14. In one configuration, coil 26 may be wrapped
in the following order: 26A to 26D to 26B to 26E to 26C to 26F.
Although FIGS. 2A and 2B show coil 26 to be wrapped in a helical
configuration, other configurations can be used without departing
from the scope of the intended invention. Each individual coil turn
26A, 26B, 26C, 26D, 26E, 26F is separated from one another and from
return pole 20 and write pole 22 by insulator 28. Write coil 26 is
generally formed from an electrically-conductive metal, such as Cu,
Au, or Ag. Most commonly used is Cu, which has a CTE in the range
of about 16.0.times.10.sup.-6/.degree. C. to
18.0.times.10.sup.6-/.degree. C.
[0033] Insulator 28 surrounds write coil 26 and is preferably
formed from a dielectric material with high thermal conductivity to
facilitate the removal of heat from write coil 26 via return pole
20 and write pole 22. Insulator 28 is preferably formed from
Al.sub.20.sub.3 or a photoresist having a large CTE.
[0034] In the first embodiment of contact enhancement feature 12A
shown in FIGS. 2A and 2B, contact enhancement feature 12A is formed
from aluminum oxide (alumina) deposited on top of write pole 22.
During manufacturing of magnetic head 10, magnetic head is formed
in an argon-filled environment. However, because alumina is
adversely affected by argon, when alumina is deposited in the
manufacturing of magnetic head 10, the level of argon is decreased.
Due to the decrease in argon during the deposition of alumina, when
the alumina is initially deposited on the walls of a tall feature
at the wafer level, it forms a mass of hard alumina 30 proximate
write coil 26. In certain applications, this mass has the same
height relative to the SIS as the write pole 22. The mass of hard
alumina 30 formed above write coil 26 shown in FIG. 2A can then be
etched into contact enhancement feature 12A. Thus, by controlling
the argon content during alumina deposition and controlling the
lapping, etching, and cleaning processes used in making magnetic
head 10, contact enhancement feature 12A shown in FIG. 2B is
obtained from protruded alumina above write coil 26.
[0035] Protrusion of write pole 22 may also be controlled by
positioning a material, other than alumina, that is difficult to
mill or lap during SIS planarization close to write pole 22. The
material functions to ensure that write pole 22 is not
over-recessed by protecting write pole 22 from lapping and/or
milling below the level of surrounding write head features. The
material can include, but is not limited to: SiC, Ta, Cr, or any
other material that is difficult to mill or lap.
[0036] FIGS. 3A and 3B show a second embodiment of contact
enhancement feature 12B prior to lapping and after lapping,
respectively. As previously noted, it is important to minimize the
difference in height between write pole tip 14 and contact
enhancement feature 12B. Because alumina tends to lap and etch
differently from metal, which write pole 22 is formed from, it may
be desirable to make contact enhancement feature 12B out of metal.
In the second embodiment, contact enhancement feature 12B is
created from write coil front shield 32, which is a detached write
coil turn 26G that does not carry any electrical current. Creating
contact enhancement feature 12B from write coil front shield 32 is
desirable because it may be implemented by changing only one of the
masks used in making magnetic head 10. During manufacture and prior
to lapping, write pole 22 and write coil 26 are created in excess
of the SIS, with the SIS line showing the location of the desired
SIS, as shown in FIG. 3A. Write coil front shield 32 is formed
during the lapping process of manufacturing magnetic head 10 when
the excess structures of write pole 22 and write coil 26 left of
the SIS line are removed, leaving a thin layer of metal from write
coil front shield 32 at the SIS, as shown in FIG. 3B. Write coil
front shield 32 serves to increase the head-media contact surface
of magnetic head 10 and indicate when the fly height of magnetic
head 10 relative to media M needs to be adjusted to prevent damage
to write pole 22.
[0037] Contact enhancement feature 12B of the second embodiment can
be made of the same material as write coil 26, such as copper.
However, using copper at the SIS presents the risk of corrosion or
undesirable topography, which may make copper unsuitable for some
applications. If copper is not a suitable choice for contact
enhancement feature 12B, then silver, which has a higher resistance
to corrosion, may be used. Silver is also a suitable candidate for
use in forming write coil 26 because it can be readily plated and
has very low electrical resistance. In addition, a designer willing
to use additional photolithographic steps can also form contact
enhancement feature 12B from NiCu.
[0038] As shown in FIGS. 3A and 3B, if contact enhancement feature
12B formed from write coil front shield 32 does not have a
sufficient surface area to create a head-media contact area wide
enough to protect write pole 22, supplementary contact enhancement
feature 34 can be formed on top of write coil 26 by plating another
layer of metal. An example of a material used to form supplementary
contact enhancement feature 34 includes but is not limited to, Cr.
In one embodiment, supplementary contact enhancement feature 34 may
also be return pole 20.
[0039] FIGS. 4A and 4B show a third embodiment of contact
enhancement feature 12C prior to lapping and after lapping,
respectively. In the third embodiment of magnetic head 10, write
coil refill 36 is used to form contact enhancement feature 12C. As
in the second embodiment of magnetic head 10 discussed in FIGS. 3A
and 3B, when magnetic head 10 is being manufactured, write pole 22
and write coil 26 are created in excess at the SIS with the SIS
line showing the location of the desired SIS (FIG. 4A). The area
between write coil turns 26A-26C of write coil 26 is filled with
write coil refill 36. Write coil refill 36 serves as a means to
reduce the height difference between write pole tip 14 and contact
enhancement feature 12C. Write coil refill 36 is formed from a
material that is lapped and etched at a rate substantially similar
to the lap and etch rate of write pole 22 and may include, but is
not limited to: SiC, W, and SiN. However, although SiC, W, and SiN
are each good conductors, they are poor insulators, so a layer of
insulator 28 is still needed between write coil turns 26A-26C. A
thin layer of atomic layer deposition alumina 38 is thus added
between write coil turns 26A-26C and write coil refill 36 to
separate write coil refill 36 from write coil 26. Contact
enhancement feature 12C is formed during lapping when the excess
structures of write pole 22 and write coil 26 left of the SIS line
are removed, leaving a layer of material at the SIS as shown in
FIG. 4B.
[0040] FIGS. 5A, 5B, and 5C show a fourth embodiment of contact
enhancement feature 12D prior to lapping, during lapping, and after
lapping, respectively. Contact enhancement feature 12D is formed
around write pole tip 14 such that write pole tip 14 is covered at
the SIS by contact enhancement feature 12D. Magnetic head 10 is
then heated such that write pole tip 14 and other elements
surrounding write pole tip 14 are thermally protruded at the SIS.
By heating the area around write pole tip 14 prior to lapping, it
is more likely that write pole tip 14 is proximate the SIS to form
at least a portion of the head-media contact surface. Contact
enhancement feature 12D and write pole tip 14 are then lapped and
burnished until the surfaces of write pole tip 14 and contact
enhancement feature 12D are substantially planar and the resulting
surface area is such that .DELTA.PES or AE contact detection
methods can be effectively used to detect contact between contact
enhancement feature 12D and media M. In one embodiment, contact
enhancement feature 12D is formed of Diamond-Like-Carbon (DLC).
[0041] FIG. 6A shows a sectional view of magnetic head 10 after
lapping but prior to exposure to any head-media contact. FIG. 6B
shows a sectional view of magnetic head 10 after lapping and after
exposure to a head-media contact. FIG. 7 shows a storage interface
surface view of protective material 40 surrounding write pole tip
14. Protective material 40 (FIG. 7) is designed to provide a small
protrusion for write pole tip 14 after the lapping process. Write
pole tip 14 is initially made such that it always slightly
protrudes from a plane defined by contact enhancement feature 12E.
During a first controlled head-media contact (made by heating,
reduced air pressure, or other means), the protruding part of write
pole tip 14 is burnished off to a height substantially equal to a
height of surrounding contact enhancement feature 12E (FIG. 6B).
After write pole tip 14 is lapped and milled, write pole tip 14
still protrudes towards media M to a greater extent than contact
enhancement feature 12E, but only slightly. Once write pole tip 14
is burnished, write pole tip 14 is no longer detrimentally pushed
towards media M during thermal expansion.
[0042] While write pole tip 14 is being burnished, its protective
cover is partly or fully removed, making write pole tip 14 more
susceptible to corrosion. Thus, burnishing should occur immediately
before or during the first electrical testing performed prior to
building magnetic head 10 into a disc drive. In addition, magnetic
head 10 may need further protection from corrosion until magnetic
head 10 is built into the disc drive. This can be accomplished by
using an easily burnishable film to temporarily protect burnished
write pole tip 14 from corrosion between the time the burnishing
occurs and the time the disc drive is assembled and sealed. For
example, a protective film that may be used is a Self-Assembled
Monolayer (SAM) film that is readily deposited in gas form, yet can
be tailored for specific chemical and mechanical properties by
manipulating backbone chain lengths as well as functional end
groups. Another example of a protective film is a SeaWax-type head
lubricant.
[0043] Protrusion of write pole 22 relative to contact enhancement
feature 1 2E can be achieved by putting protective material 40,
which is more difficult to lap and/or mill than write pole tip 14
during planarization of magnetic head 10, proximate to write pole
tip 14. However, the amount of protective material 40 is still very
small so that it is burnished off to the level of contact
enhancement feature 12E at the same time that write pole tip 14 is
being burnished. FIG. 7 shows an exemplary embodiment of protective
material 40 positioned proximately write pole tip 14. Protective
material 40 may be formed of any material that is lapped or milled
at a slower rate than other features of magnetic head 10 exposed at
the SIS, including, but not limited to: SiC, Ta, and Cr.
[0044] The magnetic head of the present invention comprises a
contact enhancement feature for increasing a head-media contact
surface of a magnetic head at the storage interface surface to
detect contact with magnetic media. A write pole tip of the
magnetic head is typically used as the head-media contact and needs
to be protected from burnishing as a result of contact with the
magnetic media. The head-media contact surface created by the
contact enhancement feature protects the write pole tip, as well as
other components of the writer. The contact enhancement feature is
positioned proximate the write pole tip and has a larger surface
area than the write pole tip, helping to create a wider head-media
contact surface around the write pole tip at the storage interface
surface. Due to the larger surface area of the contact enhancement
feature, damage to the write pole is avoided because the magnetic
media will contact the contact enhancement feature before it
contacts the write pole tip.
[0045] Although the present invention has been described with
reference to preferred embodiments, workers skilled in the art will
recognize that changes may be made in form and detail without
departing from the spirit and scope of the invention.
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