U.S. patent application number 10/706381 was filed with the patent office on 2005-05-12 for write-head having recessed magnetic material in gap region.
This patent application is currently assigned to Headway Technologies, Inc.. Invention is credited to Dovek, Moris, Garfunkel, Glen, Wang, Po Kang.
Application Number | 20050099727 10/706381 |
Document ID | / |
Family ID | 34552524 |
Filed Date | 2005-05-12 |
United States Patent
Application |
20050099727 |
Kind Code |
A1 |
Dovek, Moris ; et
al. |
May 12, 2005 |
Write-head having recessed magnetic material in gap region
Abstract
As track densities increase, it becomes increasingly important,
while writing in a given track, not to inadvertently write data in
adjoining tracks. This problem has been overcome by limiting the
width of material in the ABS plane to what it is at the write gap.
The part of the lower pole that is wider than this is recessed back
away from the ABS, thereby greatly reducing its magnetic influence
on adjacent tracks. Four different embodiments of write heads that
incorporate this notion are described together with a description
of a general process for their manufacture.
Inventors: |
Dovek, Moris; (San Jose,
CA) ; Garfunkel, Glen; (San Jose, CA) ; Wang,
Po Kang; (San Jose, CA) |
Correspondence
Address: |
STEPHEN B. ACKERMAN
28 DAVIS AVENUE
POUGHKEEPSIE
NY
12603
US
|
Assignee: |
Headway Technologies, Inc.
|
Family ID: |
34552524 |
Appl. No.: |
10/706381 |
Filed: |
November 12, 2003 |
Current U.S.
Class: |
360/125.48 ;
360/125.49; 360/125.57; G9B/5.073 |
Current CPC
Class: |
Y10T 29/49043 20150115;
Y10T 29/49044 20150115; Y10T 29/49048 20150115; Y10T 29/49052
20150115; Y10T 29/49046 20150115; G11B 5/2657 20130101; Y10T
29/49021 20150115 |
Class at
Publication: |
360/126 |
International
Class: |
G11B 005/147 |
Claims
What is claimed is:
1. A magnetic write head, having an air bearing surface,
comprising: upper and lower magnetic poles each having a first
surface, said first surfaces being parallel and non-opposing;
extending for an amount in a direction normal to said first
surfaces, one pedestal from each pole, said pedestals having second
surfaces that are coplanar, parallel to, and opposed to, said first
surfaces; said pedestals being separated from one another by a
non-magnetic layer whereby a write gap is defined; said pedestals
having a common width that defines a track width; each pedestal
extending away from said write gap for a distance whereby most of
said pole is set back some distance from said air bearing surface
and therefore has little magnetic interaction therewith.
2. The write head described in claim 1 wherein said track width is
between about 0.05 and 1 micron.
3. The write head described in claim 1 wherein said amount that
said pedestals extend away from said poles is between about 0.1 and
1 micron.
4. A magnetic write head, comprising: on a substrate, a first layer
of high magnetic permeability material that serves as a primary
lower magnetic pole; an non-magnetic layer that abuts, and extends
away from, said primary pole on a first side; a second layer of
high magnetic permeability material that serves as a secondary
lower pole and covers said primary pole extending over said
non-magnetic layer on said first side as a ledge having a width; a
field coil over, and insulated from, said lower poles; an upper
magnetic pole that overlies said field coil, contacts said lower
pole at a second side that opposes said first side, and that is
separated from said ledge by a layer of non-magnetic material that
is a write gap, said upper pole having, at the write gap, a width
equal to said ledge width, whereby it defines a track width; and
said ledge extending away from said primary lower pole by an
amount.
5. The write head described in claim 4 wherein said first layer of
high magnetic permeability material is NiFe, CoNiFe, FeTaN, FeAIN,
CoTaN, CoAIN, or CoFeN and has a thickness between about 0.3 and 3
microns.
6. The write head described in claim 4 wherein said non-magnetic
layer is silicon oxide, aluminum oxide, tantalum oxide, Al, Rh, Ru,
Cu, NiCu, or Ta.
7. The write head described in claim 4 wherein said second layer of
high magnetic permeability material is NiFe, CoNiFe, FeTaN, FeAIN,
CoTaN, CoAIN, or CoFeN and has a thickness between about 0.2 and 2
microns.
8. The write head described in claim 4 wherein said upper magnetic
pole is NiFe, CoNiFe, FeTaN, FeAIN, CoTaN, CoAIN, or CoFeN and has
a thickness between about 0.3 and 3 microns.
9. The write head described in claim 4 wherein said width is
between about 0.05 and 1 microns.
10. The write head described in claim 4 wherein said amount that
said ledge extends away from said primary lower pole is between
about 0.1 and 1 microns.
11. A stitched pole magnetic write head, comprising: on a
substrate, a first layer of high magnetic permeability material
that serves as a primary lower magnetic pole; an insulating layer
that abuts, and extends away from, said primary pole on a first
side; a second layer of high magnetic permeability material that
serves as a secondary lower pole and covers said primary pole,
extending over said insulating layer on said first side as a ledge
having a width and a length; a depression in said lower pole that
determines the value of said length; a field coil over, and
insulated from, said lower pole; an upper magnetic pole that
overlies said field coil and that contacts said lower pole at a
second side that opposes said first side; a flux concentrating
pole, that contacts said upper pole and extends downwards therefrom
above said ledge and that is separated from said ledge by a layer
of non-magnetic material, whereby it forms a write gap, said flux
concentrating pole having a width, at the write gap, equal to said
ledge width, whereby it defines a track width; and said ledge
extending beyond said primary lower pole by an amount.
12. The stitched pole magnetic head described in claim 11 wherein
the width of said ledge is between about 0.05 and 1 microns.
13. The stitched pole magnetic head described in claim 11 wherein
the length of said ledge is between about 0.1 and 1 microns.
14. The stitched pole magnetic head described in claim 11 wherein
said depression has a depth that is between about 0.1 and 1
Angstroms.
15. The stitched pole magnetic head described in claim 11 wherein
the amount said ledge extends beyond said primary lower pole is
between about 0.1 and 1 microns.
16. A magnetic write head, comprising: on a substrate, a flat
primary lower magnetic pole having a first length and first and
second ends; at a separation distance over said lower magnetic
pole, a flat upper magnetic pole having a second length that is
greater then said first length whereby said upper pole has an end,
that has a width, that projects beyond said lower pole only at said
first end; said upper pole being magnetically connected to said
lower pole at said second end; between said upper and lower poles,
a field coil that is insulated from both said poles; a secondary
lower pole having first and second parts; said first part extending
upwards from said primary lower pole's first end to a first height;
said second part extending laterally from said first part so as to
be in alignment with said upper pole end; said second part also
extending upwards to a second height above said lower pole that is
greater than said first height; and said second part being
separated from said upper pole by a layer of non-magnetic material,
whereby it forms a write gap, said second pole having a width, at
the write gap, equal to said upper pole width, whereby it defines a
track width.
17. The magnetic write head described in claim 16 wherein the first
length of said primary magnetic pole is between about 5 and 25
microns.
18. The magnetic write head described in claim 16 wherein the
separation distance over said lower magnetic pole is between about
0.05 and 0.2 microns.
19. The magnetic write head described in claim 16 wherein the width
of said upper pole end is between about 1.5 and 3 times said track
width.
20. The magnetic write head described in claim 16 wherein said
first height is between about 0.1 and 0.5 microns.
21. The magnetic write head described in claim 16 wherein said
second height is between about 0.1 and 1 microns.
22. A magnetic write head, comprising: on a substrate, a primary
lower magnetic pole having a first thickness, an upper surface, and
first and second ends; part of said primary lower pole having the
form of a shelf that extends outwards away from said first end by
an amount, while sharing said upper surface, and having a thickness
less than said first thickness; a secondary lower pole, having a
width, that extends upwards from said shelf, to a height, and
inwards from said third end by an amount; a field coil over, and
insulated from, said lower poles; and an upper magnetic pole that
overlies said field coil, contacts said primary lower pole near
said second end, and that is separated from said secondary lower
pole by a layer of non-magnetic material, whereby it forms a write
gap, said upper pole having a width, at the write gap, equal to
said secondary lower pole width, whereby it defines a track
width.
23. The magnetic read head described in claim 22 Wherein the
thickness of said primary lower magnetic pole is between about 0.5
and 3 microns.
24. The magnetic read head described in claim 22 wherein the
thickness of said shelf is between about 0.2 and 2 microns.
25. The magnetic read head described in claim 22 wherein the amount
that said shelf extends outwards is between about 0.1 and 2
microns.
26. The magnetic read head described in claim 22 wherein the width
of said secondary lower pole is between about 0.05 and 1
microns.
27. The magnetic read head described in claim 22 wherein the height
that said secondary lower pole extends upwards from said shelf is
between about 0.2 and 2 microns.
28. The magnetic read head described in claim 22 wherein the amount
that said secondary lower pole extends inwards from said third end
is between about 0.05 and 0.2 microns.
29. A process to manufacture a magnetic write head, comprising: on
a substrate, depositing and then patterning a first layer of high
magnetic permeability material to form a primary lower magnetic
pole; depositing a layer of insulating material on said substrate
and on said primary lower pole to a thickness greater than that of
said primary lower pole to form a structure; planarizing the
structure until all insulating material has been removed from over
said primary lower pole, whereby said insulating layer abuts, and
extends away from, said primary pole on one side; depositing and
patterning a second layer of high magnetic permeability material to
form a secondary lower pole that covers said primary pole and
extends over said insulating layer on said one side as a ledge
having a width; forming a field coil over, and insulated from, said
secondary lower pole; forming an upper magnetic pole that overlies
said field coil, contacts said lower pole at a location well
removed from said one side, and that is separated from said ledge
by a layer of non-magnetic material, thereby forming a write gap,
said upper pole having a width, at the write gap, equal to said
ledge width, thereby defining a track width; and through
planarizing, removing material from said ledge, said write gap, and
said upper pole until said ledge extends beyond said primary lower
pole by a final amount.
30. The process described in claim 29 further comprising: forming a
stitched pole between said write gap and said upper pole, thereby
concentrating magnetic flux from said upper pole at said write gap;
and prior to forming said field coil, etching a trench in said
lower pole whereby said shelf presents a reduced area to said upper
pole.
31. The process described in claim 29 wherein said first layer of
high magnetic permeability material is NiFe, CoNiFe, FeTaN, FeAIN,
CoTaN, CoAIN, or CoFeN and has a thickness between about 0.3 and 3
microns.
32. The process described in claim 29 wherein said insulating layer
is silicon oxide, aluminum oxide, tantalum oxide, Al, Rh, Ru, Cu,
NiCu, or Ta and is deposited to a thickness between about 1 and 2.5
microns.
33. The process described in claim 29 wherein said second layer of
high magnetic permeability material is NiFe, CoNiFe, FeTaN, FeAIN,
CoTaN, CoAIN, or CoFeN and has a thickness between about 0.2 and 2
microns.
34. The process described in claim 29 wherein said upper magnetic
pole is NiFe, CoNiFe, FeTaN, FeAIN, CoTaN, CoAIN, or CoFeN and has
a thickness between about 0.2 and 2 microns.
35. The process described in claim 29 wherein said upper pole width
at the write gap is between about 0.05 and 1 microns.
36. The process described in claim 29 wherein the final amount that
said ledge extends away from said primary lower pole is between
about 0.1 and 1 microns.
Description
FIELD OF THE INVENTION
[0001] The invention relates to the general field of magnetic write
heads with particular reference to eliminating neighboring track
erasure.
BACKGROUND OF THE INVENTION
[0002] A typical write head structure for a magnetic disk system is
schematically illustrated in FIG. 1. Its principal parts are lower
pole 12 and upper pole 11 (commonly referred to as P1 and P2,
respectively. These are magnetically connected at one end and
separated by a small non-magnetic layer 13 (the write gap) at the
other end. The track width will be defined by the P2 width at the
gap. P1 may be notched through a self aligned process, known as
partial pole trim (PPT), to better define the written transitions.
Coil 14 is located in the space enclosed by P1 and P2 and is the
source of the magnetic field that is focused by the two pole
pieces. All seen in the figure is a magnetic shield layer 16 which
is electrically isolated from the lower pole by dielectric layer
15.
[0003] FIG. 2 shows a variation on the basic design seen in FIG. 1.
In this case a secondary upper pole 21 is `stitched` in between 11
(P2) and gap 13. This is for ease of fabrication so that the track
width definition can be done on relatively flatter topography. An
additional feature, not present in the design of FIG. 1, is shallow
trench 22 which is etched into lower pole 12. Since trench 22 has
sloping sides, the depth to which it is etched can be used to fine
tune the length of lower pole 12 that is part of the write gap 13.
This is usually referred to as the throat. This allows for a
further concentration of the available flux within the write gap.
In the stitched pole design, the track width is defining part of
pole 21 as well as the back gap connection 23 which are fabricated
immediately following the deposition of write gap 13.
[0004] FIG. 3 is an isometric view of part of FIG. 1 or FIG. 2 as
seen when looking up from the magnetic track at the air bearing
surface that passes over it (so-called ABS view). It is important
to note that the surfaces of the upper pole (11 in FIG. 1 or 21 in
FIG. 2), the gap 13, and the lower pole 12, are all coplanar. One
consequence of this, the standard structure in use today, is the
unintended erasure of adjacent tracks on the disk as narrower
tracks and higher track densities are developed. Most improvements
that have been proposed, such as increased PPT depth, smooth P1
topography, and narrower gap all come with either process
challenges or reduced on track writeablity performance.
[0005] As track densities increase, the read head extracts the
recorded information from an ever decreasing narrow track. It
becomes increasingly important not to affect the integrity of this
narrow track of data. In the structure shown in FIG. 3, P2 has
magnetic material confined to the written track. P1. however, still
includes material that extends outside the track width (TW)
defining region. This may lead to unintended writing on an adjacent
track and may therefore affect the data integrity of the
system.
[0006] A routine search of the prior art was performed with the
following references of interest being found:
[0007] U.S. Pat. No. 6,353,511 B1 (Shi et al.) shows a process for
a improved Write head. U.S. Pat. No. 5,878,481 (Feng et al.) shows
a pole trimming process for a write head. U.S. Pat. No. 5,843,521
(Ju et al.) and U.S. Pat. No. 5,802,700 (Chen et al.) are related
patents. U.S. Pat. No. 5,652,687 (Chen et al.) shows a planarized
write head process.
SUMMARY OF THE INVENTION
[0008] It has been an object of at least one embodiment of the
present invention to provide a magnetic write head that does not
write unintentionally onto data tracks located on either side of
the track that is being written.
[0009] Another object of at least one embodiment of the present
invention has been that this be accomplished without a reduction in
write field strength or track density.
[0010] Still another object of at least one embodiment of the
present invention has been to provide a process for the manufacture
said write head.
[0011] A further object of at least one embodiment of the present
invention has been that said process not require significant
modification of existing processes for the manufacture of write
heads.
[0012] These objects have been achieved by limiting the width of
material in the ABS plane to what it is at the write gap. The part
of the lower pole that is wider than this is recessed away from the
ABS, thereby greatly reducing its magnetic influence on adjacent
tracks. Four different embodiments of write heads that incorporate
this notion are described together with a description of a general
process for their manufacture.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 illustrates a basic read head design.
[0014] FIG. 2 shows the basic design of FIG. 1 modified by use of a
stitched upper pole.
[0015] FIG. 3 is the ABS view of FIGS. 1 and 2 in isometric
projection.
[0016] FIG. 4 shows the structure of FIG. 1 modified according to
the teachings of the present invention.
[0017] FIG. 5 shows the structure of FIG. 2 modified according to
the teachings of the present invention.
[0018] FIG. 6 illustrates a third embodiment of the present
invention.
[0019] FIG. 7 is an isometric view of a portion of a fourth
embodiment.
[0020] FIGS. 8-12 illustrate successive steps in the manufacture of
the structure of the present invention.
[0021] FIG. 13 is a plan view of the structure of the present
invention.
[0022] FIG. 14 is an isometric view of part of a fourth embodiment
of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0023] The key novel feature of the present invention is the
restriction of the width of P1 to TW for a distance such that there
is no P1 wider than the track width at the ABS. This is achieved by
causing P1 beyond this distance to be recessed away from the ABS,
thereby greatly reducing its magnetic influence on the adjacent
tracks. Thus, the amount of P1 at the ABS should exceed the amount
of P1 that is recessed
1.sup.st Embodiment
[0024] Referring now to FIG. 4, we show there a structure that is
similar to the one shown in FIG. 1, but modified in accordance with
the teachings of the present invention. As before, upper pole 11
and lower pole 12 enclose, between them, field coil 14. The key
novel feature is ledge 41 of magnetic (high permeability) material
that extends outwards away from the main body of lower pole 12. The
outer edge of ledge 41 has the same width as, and is in alignment
with, the outer edge of top pole 11 so that write gap 13 lies
between them and said widths define the track width TW. As a
result, most of bottom pole 12 is set back some distance from the
ABS and so has relatively little magnetic interaction with the disk
surface. FIG. 7 is an isometric view that illustrates the spatial
relationships between top pole 11 and bottom poles 41 and 12.
[0025] For purposes of simplification, FIG. 4 has been drawn as
though ledge 41 is a cantilever. In actuality, a layer of
insulation is present below 41 to support it. Details of this
support layer are provided later, in the section where we describe
the process for manufacturing this structure.
2.sup.nd Embodiment
[0026] FIG. 5 shows a structure similar that seen in FIG. 2. As
before, there is a general similarity to the first embodiment
illustrated in FIG. 4 with the addition of stitched secondary top
pole 21 and shallow trench 22. The key departure is the addition to
the structure of ledge 51, which analogous to ledge 41 of the first
embodiment, and serves the same purpose. FIG. 7 is an isometric
view that illustrates the spatial relationships between top pole 21
and bottom poles 51 and 12 while FIG. 13 is a plan view of this
structure.
3.sup.rd Embodiment
[0027] This variation of the basic structure is sometimes preferred
because certain parts, such as pole 11, are easier to manufacture.
By going to a somewhat thicker inter-pole connector 23 and using a
single turn for field coil 23, top pole 11 can be flat rather than
humped, as in the previous two embodiments. The bottom pole in this
case is composed of two layers, 62 and 12, which, in prior art
versions of this variant (not shown), would extend from bottom pole
12 all the way to write gap 13.
[0028] As seen in FIG. 6, in the structure of the present invention
the secondary bottom pole is in two parts 62 and 63. Part 62
extends upwards from bottom pole 12 but not all the way to write
gap 13. This leaves room for second part 63 which, in addition to
extending the rest of the way up to the write gap, also extends
laterally away from part 62 so as to be aligned with the ABS end of
top pole 11. As a result, the lower part of the secondary bottom
pole and all of the main bottom pole 12 are set back from the ABS,
thereby reducing their magnetic interaction with the write
track.
4.sup.th Embodiment
[0029] This embodiment, illustrated in FIG. 14, entails still
further modification of the three embodiments just discussed. In
all three cases, there is no recessing of the secondary lower
poles, recessing being delayed so that portion 12a of the primary
lower pole also remains coplanar with the ABS. The remainder 12b of
the primary lower pole is recessed as in the previous embodiments.
This embodiment is unsuitable for extremely high track densities
(greater than about 125,000 tracks per inch) but for lesser
densities its advantage is manufacturability; the thickness and
height of 12a (the non-recessed part of P1) and the depth of the
partial pole trim (41, 51, 62) do not need to be the same.
Manufacturing Process
[0030] Referring now to FIG. 8, the process of the present
invention begins with the provision of substrate 15 on which is
deposited, and then patterned, layer 12 of a high magnetic
permeability material to form the primary lower pole. Next, as seen
in FIG. 9, layer of insulating material 91 is deposited on
substrate 15 as well as on primary lower pole 12, making sure that
its thickness exceeds that of 12.
[0031] The structure is then planarized until all insulating
material has been removed from over the primary lower pole so that
the remaining insulation abuts, and extends away from, the primary
pole. This is illustrated in FIG. 10. Second layer 110 of high
magnetic permeability material is next deposited and patterned to
form a secondary lower pole that covers primary pole 12 and extends
over insulating layer 91 on one side so as to form ledge 112.
Optionally, an additional layer 114 of insulation may be introduced
(in the same way as just described for 91) to fill in the part
above 91 that is not covered by 110. Since 110 is relatively thin,
this step may be omitted without significant consequence.
[0032] In the case of the second embodiment (FIG. 5), shallow
trench 22 is formed at this time. For all embodiments, completion
of the structure now proceeds along routine lines--field coil 14 is
formed over, and insulated from, the lower poles following which
the upper magnetic pole 11 is formed to overlie it. At one end the
two poles are in magnetic contact with one another while at the
other end they are by layer of non-magnetic material 13 to form the
write gap whose width serves to define the track width TW. Finally,
the ABS end of the structure is planarized as far as plane 115,
thereby determining how far ledge 112 extends out away from the
main body of the lower pole.
* * * * *