U.S. patent application number 12/961939 was filed with the patent office on 2012-06-07 for magnetic head, head assembly, and magnetic recording/reproducing apparatus to reduce risk of wide area track erase.
This patent application is currently assigned to TDK CORPORATION. Invention is credited to Kenkichi Anagawa, Kei Hirata, Minoru OTA.
Application Number | 20120140361 12/961939 |
Document ID | / |
Family ID | 46162029 |
Filed Date | 2012-06-07 |
United States Patent
Application |
20120140361 |
Kind Code |
A1 |
OTA; Minoru ; et
al. |
June 7, 2012 |
MAGNETIC HEAD, HEAD ASSEMBLY, AND MAGNETIC RECORDING/REPRODUCING
APPARATUS TO REDUCE RISK OF WIDE AREA TRACK ERASE
Abstract
A magnetic head includes a main magnetic pole layer and a yoke
layer. The main magnetic pole layer generates a magnetic flux of a
recording magnetic field and includes a magnetic pole front part
and a magnetic pole rear part. The yoke layer is disposed at the
magnetic pole rear part and includes a yoke front part and a yoke
rear part. The magnetic pole front part extends on a magnetic
medium-facing surface side of the magnetic pole rear part with a
width in a track width direction being smaller than that of the
magnetic pole rear part. The yoke front part extends on the
magnetic medium-facing surface side of the yoke rear part with a
width in the track width direction being larger than that of the
magnetic pole rear part and that of the yoke rear part.
Inventors: |
OTA; Minoru; (Tokyo, JP)
; Hirata; Kei; (Tokyo, JP) ; Anagawa;
Kenkichi; (Tokyo, JP) |
Assignee: |
TDK CORPORATION
Tokyo
JP
|
Family ID: |
46162029 |
Appl. No.: |
12/961939 |
Filed: |
December 7, 2010 |
Current U.S.
Class: |
360/294 ;
360/125.12; G9B/21.028; G9B/5.04 |
Current CPC
Class: |
G11B 19/045 20130101;
G11B 5/1278 20130101; G11B 5/3116 20130101; G11B 5/3163
20130101 |
Class at
Publication: |
360/294 ;
360/125.12; G9B/5.04; G9B/21.028 |
International
Class: |
G11B 5/127 20060101
G11B005/127; G11B 21/24 20060101 G11B021/24 |
Claims
1. A magnetic head comprising a main magnetic pole layer and a yoke
layer, the main magnetic pole layer being capable of generating a
magnetic flux of a recording magnetic field and including a
magnetic pole front part and a magnetic pole rear part, the yoke
layer being disposed at the magnetic pole rear part and including a
yoke front part and a yoke rear part, the magnetic pole front part
extending on a magnetic medium-facing surface side of the magnetic
pole rear part with a width in a track width direction being
smaller than that of the magnetic pole rear part, and the yoke
front part extending on the magnetic medium-facing surface side of
the yoke rear part with a width in the track width direction being
larger than that of the magnetic pole rear part and that of the
yoke rear part.
2. The magnetic head of claim 1, wherein the width of the magnetic
pole rear part and/or the yoke rear part in the track width
direction is constant.
3. The magnetic head of claim 1, wherein the width of the yoke
front part in the track width direction is constant.
4. The magnetic head of claim 1, wherein the width of the yoke
front part in the track width direction increases toward the
magnetic medium-facing surface.
5. The magnetic head of claim 1, wherein the yoke front part
includes a first area and a second area, the first area extending
on the magnetic medium-facing surface side of the second area with
a constant width in a track width direction, the second area
widening with a width in the track width direction increasing
toward the magnetic medium-facing surface from the same width as
the yoke rear part to the same width as the first area.
6. The magnetic head of claim 1, wherein the yoke front part and
the magnetic pole rear part have aligned ends on the magnetic
medium-facing surface side.
7. The magnetic head of claim 1, wherein the yoke rear part and the
magnetic pole rear part have aligned ends on a side remote from the
magnetic medium-facing surface.
8. The magnetic head of claim 2, wherein a ratio of an overall
length of the yoke layer in a height direction to a length of the
yoke rear part in the height direction is from 8:2 to 8:7.
9. The magnetic head of claim 2, wherein a width ratio of the yoke
rear part to the yoke front part in the track width direction at an
end on the magnetic medium-facing surface side is from 6:11 to
6:13.
10. A head assembly comprising a magnetic head and a head support
device, wherein the magnetic head is claimed in claim 1, and the
head support device supports the magnetic head in such a manner as
to permit rolling and pitching of the magnetic head.
11. A magnetic recording/reproducing apparatus comprising a head
assembly and a magnetic recording medium, wherein the head assembly
is claimed in claim 10 and capable of recording information on the
magnetic recording medium by applying the recording magnetic field
and reproducing information from the magnetic recording medium.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a magnetic head, a head
assembly, and a magnetic recording/reproducing apparatus.
[0003] 2. Description of the Related Art
[0004] In order to improve writing performance of information,
various improvements have been made in a perpendicular recording
magnetic head to be used for a magnetic recording/reproducing
apparatus such as a hard disk drive (HDD). In particular, research
and development have been vigorously conducted regarding the
problem of accidentally erasing information recorded on a magnetic
disk being a recording medium.
[0005] For example, Japanese Unexamined Patent Application
Publication No. 2006-164463 discloses a technology in which a
return path layer for absorbing a return magnetic flux from a
magnetic disk is shaped to have a width increasing toward a
floating surface, thereby reducing the magnetic field strength at
its ends in a track width direction.
[0006] Moreover, Japanese Unexamined Patent Application Publication
No. 2008-276902 discloses a technology in which an auxiliary yoke
layer laid on a main magnetic pole layer is provided with a
distinctive flared part, thereby preventing the occurrence of pole
lock-up.
[0007] Furthermore, Japanese Unexamined Patent Application
Publication No. 2008-276819 discloses a technology in which an
auxiliary yoke layer for circulating a magnetic flux from a return
path layer to a main magnetic pole layer is formed across a
plurality of layers in the manner of multi-stage connection,
thereby stabilizing magnetization components of individual layers
in a track width direction based on shape anisotropy.
[0008] Meanwhile, the present inventors tried to improve writing
performance, based on their unique viewpoint, by uniformly
narrowing the track-wise widths of a main magnetic pole layer and
an auxiliary yoke layer laid thereon. As a result, it has been
found that characteristics such as recording magnetic field
strength, bit error rate (BER), and S/N can be improved,
particularly, in a low-amperage range and a high-frequency range of
a write current to be supplied to a coil. That is, the above
improvement results in improving magnetic saturation
characteristics of a magnetic head with respect to the write
current.
[0009] However, on the other hand, it has also been found that the
strength of a recording magnetic field to be applied to tracks
adjacent to a target track for writing can be increased as compared
with the one having a conventional width, increasing the risk of
wide area track erase (WATE).
SUMMARY OF THE INVENTION
[0010] It is an object of the present invention to provide a
magnetic head, a head assembly, and a magnetic
recording/reproducing apparatus capable of reducing the risk of
wide area track erase while improving magnetic saturation
characteristics.
1. Magnetic Head
[0011] In order to achieve the above object, a magnetic head
according to the present invention comprises a main magnetic pole
layer, a yoke layer, and a return path magnetic pole layer.
[0012] The main magnetic pole layer is capable of generating a
magnetic flux of a recording magnetic field and includes a magnetic
pole front part and a magnetic pole rear part. The yoke layer is
disposed at the magnetic pole rear part and includes a yoke front
part and a yoke rear part. The return path magnetic pole layer is
connected to the yoke rear part in such a manner as to return the
magnetic flux of the recording magnetic field to the main magnetic
pole layer.
[0013] In the above, the magnetic pole front part extends on a
magnetic medium-facing surface side of the magnetic pole rear part
with a width in a track width direction being smaller than that of
the magnetic pole rear part and decreasing toward the magnetic
medium-facing surface.
[0014] On the other hand, the yoke front part extends on the
magnetic medium-facing surface side of the yoke rear part with a
width in the track width direction being larger than that of the
magnetic pole rear part and that of the yoke rear part.
[0015] The magnetic head according to the present invention
comprises the main magnetic pole layer capable of generating a
magnetic flux of a recording magnetic field, the yoke layer
disposed at the main magnetic pole layer, and the return path
magnetic pole layer connected to a yoke rear part in such a manner
as to return the magnetic flux of the recording magnetic field to
the main magnetic pole layer. Thus, they constitute a magnetic
circuit having a path through which the magnetic flux of the
recording magnetic field goes back to the return path magnetic pole
layer, from the main magnetic pole layer, through an external
magnetic recording medium and then goes back to the main magnetic
pole layer through the yoke layer.
[0016] Since the width of the magnetic pole front part in the track
width direction is smaller than that of the magnetic pole rear part
and decreases toward the magnetic medium-facing surface, the
magnetic flux from the magnetic pole rear part can be concentrated
toward the end face on the magnetic medium-facing surface side.
This increases the strength of a recording magnetic field flowing
from the magnetic medium-facing surface to the magnetic recording
medium, thereby improving magnetic saturation characteristics.
[0017] The most distinctive feature of the magnetic head according
to the present invention resides in the shape of the yoke
layer.
[0018] Since the width of the yoke front part in the track width
direction is larger than that of the magnetic pole rear part and
that of the yoke rear part, a part of a magnetic flux flowing from
the magnetic pole rear part to the magnetic pole front part can be
dispersed toward both ends in the track width direction or the
vicinity thereof. Thus, at the magnetic pole front part, the
magnetic flux can be prevented from excessively concentrating on
the end face on the magnetic medium-facing surface side.
[0019] Therefore, the magnetic head according to the present
invention can reduce the strength of a recording magnetic field to
be applied to tracks adjacent to a target track for writing.
2. Head Assembly
[0020] In order to achieve the above object, a head assembly
according to the present invention comprises the above magnetic
head and a head support device.
[0021] The head support device supports the magnetic head in such a
manner as to permit rolling and pitching of the magnetic head.
[0022] In the present invention, examples of the head assembly
include an HGA (head gimbal assembly) in which the magnetic head is
mounted on a head support device (gimbal) and an HAA (head arm
assembly) in which the HGA is mounted on an arm.
[0023] Since the head assembly according to the present invention
includes the above magnetic head, it also exhibits the effects thus
far described.
3. Magnetic Recording/Reproducing Apparatus
[0024] A magnetic recording/reproducing apparatus according to the
present invention comprises the above head assembly and a magnetic
recording medium. The head assembly is capable of recording
information on the magnetic recording medium by applying the
recording magnetic field and reproducing information from the
magnetic recording medium. A typical example of the magnetic
recording/reproducing apparatus is a hard disk drive (HDD) using a
magnetic recording medium called "hard disk".
[0025] Since the head assembly according to the present invention
includes the above magnetic head, it also exhibits the effects thus
far described.
[0026] The other objects, constructions and advantages of the
present invention will be further detailed below with reference to
the attached drawings. However, the attached drawings show only
illustrative examples.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] FIG. 1 is a perspective view of a magnetic head according to
the present invention;
[0028] FIG. 2 is a partial sectional view taken along line 2-2 in
FIG. 1;
[0029] FIG. 3 is an enlarged view of FIG. 2 near a main magnetic
pole layer on the side of a magnetic medium-facing surface;
[0030] FIG. 4 is a partial plan view of a magnetic medium-facing
surface of a magnetic head;
[0031] FIG. 5 is a plan view of a return path magnetic pole layer
and a main magnetic pole layer as seen from a lamination plane;
[0032] FIG. 6 is a plan view of a main magnetic pole layer and a
yoke layer as seen from a lamination plane;
[0033] FIG. 7 a plan view of a main magnetic pole layer and a yoke
layer of a conventional magnetic head as seen from a lamination
plane;
[0034] FIG. 8 is a characteristic graph of a write magnetic field
strength with respect to a write current, comparing a magnetic head
according to the present invention with a conventional magnetic
head;
[0035] FIG. 9 is a characteristic graph of a write magnetic field
strength with respect to a distance from a target track for
writing, comparing a magnetic head according to the present
invention with a conventional magnetic head;
[0036] FIG. 10 is a characteristic graph of a write magnetic field
strength with respect to a write current when a spread angle of a
second area of a yoke front part is varied;
[0037] FIG. 11 is a characteristic graph of a write magnetic field
strength with respect to a distance from a target track when a
spread angle of a second area of a yoke front part is varied;
[0038] FIG. 12 is a plan view of a main magnetic pole layer and a
yoke layer as seen from a lamination plane of a magnetic head
according to another embodiment;
[0039] FIG. 13 is a characteristic graph of a write magnetic field
strength with respect to a write current when a length of a yoke
front part in a height direction is varied;
[0040] FIG. 14 is a characteristic graph of a write magnetic field
strength with respect to a distance from a target track when a
length of a yoke front part in a height direction is varied;
[0041] FIG. 15 is a characteristic graph of a write magnetic field
strength with respect to a write current when a width of a yoke
rear part in a track width direction is varied;
[0042] FIG. 16 is a characteristic graph of a write magnetic field
strength with respect to a distance from a target track when a
width of a yoke rear part in a track width direction is varied;
[0043] FIG. 17 is a characteristic graph of a write magnetic field
strength with respect to a write current when a width of a yoke
front part in a track width direction is varied;
[0044] FIG. 18 is a characteristic graph of a write magnetic field
strength with respect to a distance from a target track when a
width of a yoke front part in a track width direction is
varied;
[0045] FIG. 19 is a plan view of a main magnetic pole layer and a
yoke layer as seen from a lamination plane of a magnetic head
according to another embodiment;
[0046] FIG. 20 is a plan view of a main magnetic pole layer and a
yoke layer as seen from a lamination plane of a magnetic head
according to another embodiment;
[0047] FIGS. 21(a) to 21(m) are sectional views showing a
production process of a magnetic head as seen from a magnetic
medium-facing surface;
[0048] FIGS. 22(a) to 22(f) are sectional views showing a
production process of a magnetic head as seen from a section in a
height direction;
[0049] FIGS. 23(a) and 23(b) are sectional views showing a
production process of a magnetic head as seen from a lamination
plane;
[0050] FIG. 24 is a top view of an HGA;
[0051] FIG. 25 is a bottom view of a HGA;
[0052] FIG. 26 is a plan view of an HAA; and
[0053] FIG. 27 is a perspective view of an internal structure of a
magnetic recording/reproducing apparatus.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
1. Magnetic Head
[0054] FIG. 1 shows an exemplary appearance of a magnetic head
according to the present invention. The magnetic head has a slider
substrate B of a generally rectangular prism structure and an air
bearing surface A directly relating to floating characteristics.
The air bearing surface A is configured to generate a pressure for
floating the magnetic head utilizing viscosity of fluid flow Fs
generated by rotation of a magnetic disk.
[0055] FIG. 2 shows a section taken along line 2-2 in FIG. 1.
Referring to this figure, the layer structure of the magnetic head
HD will be described below.
[0056] In the following description, dimensions along the X, Y, and
Z axes shown in the figure are designated "width", "length", and
"thickness", respectively. Along the Y axis, moreover, one side
close to the magnetic medium-facing surface A and the other side
remote therefrom are designated "front" and "rear", respectively.
Furthermore, upper and lower sides in the figure are designated
"trailing side" and "leading side", respectively.
[0057] The magnetic head HD is formed by stacking, on a substrate
1, an insulating layer 2, a reproducing head R using
magneto-resistive effect (MR), a separating layer 6, a recording
head W for performing a recording process in a perpendicular
recording system, and an overcoat layer 21 in the named order. The
air bearing surface A is one side face shared by these elements and
opposed to a surface of a magnetic recording medium M.
[0058] The substrate 1 is made of a ceramic material such as AlTiC
(Al.sub.2O.sub.3.TiC) or the like. The insulating layer 2, the
separating layer 6, and the overcoat layer 21 are made of a
non-magnetic insulating material such as aluminum oxide or the
like. The aluminum oxide may be alumina (Al.sub.2O.sub.3) or the
like.
[0059] The reproducing head R is formed by stacking a lower read
shield layer 3, a shield gap layer 4, and an upper read shield
layer 5 in the named order. In the shield gap layer 4, a
reproducing element S is embedded with one end face exposed on the
magnetic medium-facing surface A.
[0060] Both the lower read shield layer 3 and the upper read shield
layer 5 magnetically separate the reproducing element S from the
surroundings and extend rearward from the magnetic medium-facing
surface A. The lower read shield layer 3 and the upper read shield
layer 5 are made of a magnetic material such as nickel-iron alloy
(NiFe). The nickel-iron alloy may be permalloy, for example. Here,
the lower read shield layer 3 and the upper read shield layer 5 may
have a single layer structure or a multilayer structure in which a
non-magnetic layer made of a non-magnetic insulating material such
as ruthenium (Ru) or alumina is sandwiched between a pair of
magnetic layers made of a magnetic material such as permalloy, for
example.
[0061] Moreover, the shied gap layer 4 electrically separates the
reproducing element S from the surroundings and is made of a
non-magnetic insulating material such as alumina. The reproducing
element S is an element having a giant magneto-resistive effect
(GMR) or a tunneling magneto-resistive effect (TMR), and typically
a TMR element may be employed.
[0062] On the other hand, the recording head W includes a magnetic
layer 7, a leading shield layer 23, a main magnetic pole layer 13,
a non-magnetic layer 14, a yoke layer 22, a trailing shield layer
15, a trailing gap layer 16, a second magnetic layer 27, thin film
coils 10a, 10b, a return path magnetic pole layer 20, and
insulating layers 8, 9, 11, 12, 17, 18, 19, 29.
[0063] The magnetic layer 7 serves as a return path on the leading
side and is made of a magnetic material such as NiFe or CoNiFe.
With this magnetic layer 7, a part of a magnetic flux .phi. emitted
from the main magnetic pole layer 13 can be dispersed toward the
leading side to reduce a WATE effective magnetic field. The WATE
effective magnetic field refers to an effective magnetic field
which has an effect on a wide area of adjacent tracks (for example,
within the area of 2 to 10 lanes from a target track for
writing).
[0064] The thin film coils 10a, 10b are made of a highly conductive
material such as copper into a spiral shape and generate a
recording magnetic field according to information to be recorded on
the magnetic recording medium M. Spaces between windings of the
lower coil layer 10a are filled with the insulating layer 9, which
is further surrounded by the insulating layer 11, and on its front
side, there is formed the leading shield layer 23. On the other
hand, spaces between windings of the upper coil layer 10b are
filled with the insulating layer 19, and on its leading side, there
is formed the insulating layer 18.
[0065] The insulating layers 9, 19 are made of a non-magnetic
insulating material such as photoresist or spin-on glass (SOG),
while the insulating layers 11, 12, 18 are made of a non-magnetic
insulating material such as alumina. These insulating layers 9, 11,
12, 18, 19 electrically separate the thin film coils 10a, 10b from
the surroundings.
[0066] The main magnetic pole layer 13 is made of a magnetic
material with a high saturation density such as iron-cobalt alloy
or iron-cobalt-nickel alloy and has a pole tip 13c exposed on the
recording medium-facing surface A and extends rearward from the
pole tip 13c. The main magnetic pole layer 13 emits the magnetic
flux .phi. from the recording medium-facing surface A into the
magnetic recording medium M with the recording magnetic field
generated from the thin film coils 10a, 10b.
[0067] The non-magnetic layer 14 is made of a non-magnetic material
such as ruthenium and laid on the main magnetic pole layer 13.
Furthermore, the insulating layer 17, which is made of a
non-magnetic insulating material such as alumina, is laid on the
non-magnetic layer 14. The insulating layer 17 has a front end face
which defines a throat height TH and a throat height zero position
TP.
[0068] The trailing shield layer 15 mainly has a function of
increasing the perpendicular magnetic field gradient and is laid
over the main magnetic pole layer 13 and the non-magnetic layer 14
with the trailing gap layer 16 and the second magnetic layer 27
between. The trailing shield layer 15 is preferably made of a
magnetic material having a high saturation magnetic flux density
such as cobalt-nickel-iron alloy, nickel-iron alloy or iron-based
alloy.
[0069] The trailing gap layer 16 is made of a non-magnetic material
such as alumina and magnetically separates the main magnetic pole
layer 13 and the trailing shield layer 15.
[0070] The second magnetic layer 27 is disposed beneath the
trailing shield layer 15 and is made of a magnetic material having
a high saturation magnetic flux density such as iron, nickel or
cobalt-iron alloy.
[0071] FIG. 3 shows an enlarged view of FIG. 2 near the main
magnetic pole layer 13 on the side of the magnetic medium-facing
surface A. The main magnetic pole layer 13 and the non-magnetic
layer 14 have a continuous tapered face 13a, 14a opposed to a lower
side 15a of the trailing shield layer 15. The tapered face 13a, 14a
extends from the trailing edge TE of the pole tip 13c at a constant
inclination angle .theta..sub.1. In other words, the tapered face
13a of the main magnetic pole layer 13 and the tapered face 14a of
the non-magnetic layer 14 form a single continuous slope of a
constant inclination angle .theta..sub.1.
[0072] Here, the angle .theta..sub.1 may be properly set, for
example, within the range of 15 to 30 degrees. In addition, a
distance L1 between the magnetic medium-facing surface A and a rear
end of the tapered face 13a of the main magnetic pole layer 13 is,
for example, 120 (nm), while a distance L2 between the magnetic
medium-facing surface A and a rear end of the tapered face 14a of
the non-magnetic layer 14 is, for example, 270 (nm). Moreover, a
thickness d of the non-magnetic layer 14 is, for example, 70 (nm).
However, these values are mere examples and may be determined
properly depending on design.
[0073] With this configuration, a part of the tapered face 13a, 14a
is formed of the non-magnetic layer 14, which makes it possible to
reduce an area of the tapered face 13a of the main magnetic pole
layer 13 opposed to the lower side 15a of the trailing shield layer
15. Therefore, a leakage magnetic flux flowing from the main
magnetic pole layer 13 to the trailing shield layer 15 can be
minimized by properly setting the above-described parameters L1,
L2, d, or the like.
[0074] Moreover, the end 14a of the non-magnetic layer 14 on the
side of the magnetic medium-facing surface A becomes a part of the
tapered face 13a, 14a. Therefore, as compared with the case where
the above-mentioned end 14a is not a tapered face but an end face
generally parallel to the magnetic medium-facing surface A, it is
possible to increase a volume of the trailing shield layer 15.
[0075] A tolerance of the trailing shield layer 15 for magnetic
saturation can be improved by suppressing the leakage magnetic flux
to the trailing shield layer 15 and increasing the volume of the
trailing shield layer 15, as described above, so that an excellent
magnetic field gradient can be obtained to improve the bit error
rate.
[0076] The main magnetic pole layer 13 also has a second tapered
face 13b extending from the leading edge LE of the pole tip 13c.
Here, an inclination angle .theta..sub.2 of the second tapered face
13b with respect to the lamination plane (X-Y plane) may be
properly set within the range of about 15 to 60 degrees. The second
tapered face 13b reduces the thickness of the main magnetic pole
layer 13, concentrating the magnetic flux of the magnetic field
emitted from the main magnetic pole layer 13.
[0077] FIG. 4 shows a layer structure on the magnetic medium-facing
surface A in a front view. The pole tip 13c has an inverted
trapezoid shape, wherein a trailing edge TE has a larger width than
a leading edge LE. The upper side of the inverted trapezoid shape,
i.e., the trailing edge TE is a substantial recording portion of
the main magnetic pole layer 13, and its width defines the
recording track width. Typically, the recording track width is
approximately 0.2 .mu.m or less.
[0078] Moreover, the main magnetic pole layer 13 is enclosed by the
leading shield layer 23 on the leading side, by the side shields 25
on both sides in the lamination plane, and by the trailing shield
layer 15 on the trailing side. The leading shield layer 23, the
trailing shield layer 15, and the side shields 25 are made of, for
example, a magnetic material similar to that of the main magnetic
pole layer 13 and absorbs the magnetic flux mainly in the vicinity
of the magnetic medium-facing surface A to prevent dispersion of
the magnetic flux. This increases the magnetic field gradient and
also narrows the recording track width.
[0079] The leading shield layer 23, the trailing shield layer 15,
and the side shields 25 are each exposed on the magnetic
medium-facing surface A and extend from the exposed end face to the
throat height zero position TP behind it. The trailing shield layer
15 and the side shields 25 are adjacent to the insulating layer 17
at each rear end.
[0080] The leading shield layer 23 is formed to be opposed to the
leading side of the main magnetic pole layer 13 across the
insulating layer 12. The leading shield layer 23 is not an
essential component for the magnetic head and may be provided if
necessary.
[0081] The side shields 25 are formed to sandwich the main magnetic
pole layer 13 from both sides with a pair of side gaps 121 between.
The pair of side gaps 121 are made of an insulating material and
extend from the insulating layer 12 toward the trailing side along
both sides of the pole tip 13c, thereby magnetically separating the
main magnetic pole layer 13 and the side shields 25.
[0082] In the side shields 25 and the leading shield layer 23,
portions 251, 231 having a lower saturation magnetic flux density
than other portions are provided adjacent to the side gaps 121 and
the insulating layer 12, respectively. The portions 251, 231 can be
obtained, for example, by applying an alloy whose composition ratio
is different from that of other portions and have an effect of
increasing the above-described magnetic field gradient while
suppressing the WATE effective magnetic field as compared with the
case where they are formed with a uniform saturation magnetic flux
density.
[0083] The trailing gap layer 16 and the second magnetic layer 27
are provided only in the vicinity of the upper side of the pole tip
13c as seen from the magnetic medium-facing surface A. This
prevents excessive dispersion of the magnetic flux .phi. emitted
from the pole tip 13c.
[0084] As shown in FIG. 2, the magnetic flux .phi. emitted from the
pole tip 13c can be absorbed by the trailing shield layer 15 and
the return path magnetic pole layer 20 through a soft under layer
and the like of the magnetic recording medium M.
[0085] FIG. 5 shows the return path magnetic pole layer 20 as seen
from the lamination plane (X-Y plane) of the magnetic head. The
return path magnetic pole layer 20 has a rectangular plan shape of
a width W3 and is made of, for example, a magnetic material similar
to that of the trailing shield layer 15 to have a function of
circulating the magnetic flux.
[0086] On the trailing side of the trailing shield layer 15, the
return path magnetic pole layer 20 has an end face exposed on the
magnetic medium-facing surface A and extends from it over the upper
coil layer 10a and the insulating layer 19 to a back gap BG. That
is, the return path magnetic pole layer 20 is connected to the
trailing shield layer 15 at the front and then connected to the
rear part of the yoke layer 22 at the rear through the back gap BG
so as to return the magnetic flux .phi. of the recording magnetic
field to the main magnetic pole layer 13. However, the function of
circulating the magnetic field may be provided not only to the
return path magnetic pole layer 20 but also to the trailing shield
layer 15 and the side shields 25.
[0087] As indicated by dotted lines in FIG. 5, moreover, a magnetic
pole front part 131 of the main magnetic pole layer 13 on the side
of the magnetic medium-facing surface A includes a first tip part
1311 which has a constant width W1 being the recording track width
and a second tip part 1312 whose track width increases rearward
from the width W1 to a width W2. The position at which the width
starts to increase is defined as flare point FP and the distance
between the flare point FP and the magnetic medium-facing surface A
is defined as neck height NH.
[0088] The yoke layer 22 is made of a magnetic material similar to
or different from that of the main magnetic pole layer 13 and is
directly laid on the main magnetic pole layer 13 behind the
non-magnetic layer 14, as shown in FIG. 2. Thus, the yoke layer 22
serves as an auxiliary magnetic flux storage area for supplying a
magnetic flux to the main magnetic pole layer 13. In addition, the
yoke layer 22 is connected to the non-magnetic layer 14 and the
insulating layer 17 at a front end and connected to the insulating
layer 29 at a rear end along with a rear end of the main magnetic
pole layer 13. The insulating layer 29 is made of a non-magnetic
insulating material such as alumina and disposed between a rear
part of the return path magnetic pole layer 20 and a rear part of
the insulating layer 12.
[0089] The characteristic feature of the magnetic head according to
the present invention resides in the shape of the yoke layer 22 and
the shape of the main magnetic pole layer 13 in the lamination
plane. FIG. 6 shows the shape of the main magnetic pole layer 13
and the shape of the yoke layer 22 as seen from the lamination
plane of the magnetic head.
[0090] In addition to the above-mentioned magnetic pole front part
131, the main magnetic pole layer 13 includes a magnetic pole rear
part 132 extending behind the magnetic pole front part 131. The
magnetic pole rear part 132 has a rectangular shape with a constant
width W4 in the track width direction. On the other hand, the
magnetic pole front part 131 extends on the magnetic medium-facing
surface A side of the magnetic pole rear part 132, and its width in
the track width direction is smaller than that of the magnetic pole
rear part 132 and decreases from the width W2 to the width W1
toward the magnetic medium-facing surface A, as described
above.
[0091] On the other hand, the yoke layer 22 is disposed at the
magnetic pole rear part 132 and includes a yoke front part 221 and
a yoke rear part 222. The yoke rear part 222 is connected to the
return path magnetic pole layer 20 and has the same constant width
W4 in the track width direction as the magnetic pole rear part 132.
The width W4 of the yoke rear part 222 in the track width direction
may be equal to or different from the width of the magnetic pole
rear part 132 and, moreover, is not required to be constant, as
will be described later.
[0092] The yoke front part 221 extends on the magnetic
medium-facing surface A side of the yoke rear part 222 and has a
width W5 in the track width direction which is larger than that of
the yoke rear part 222. That is, these widths satisfy the
relationship of W5>W4.
[0093] More specifically, the yoke front part 221 includes a
rectangular first area 221a and a trapezoidal second area 221b. The
first area 221a extends on the magnetic medium-facing surface A
side of the second area 221b and has a constant width W5 in the
track width direction. The second area 221b widens with a width in
the track width direction increasing toward the magnetic
medium-facing surface A from the same width W4 as the yoke rear
part 222 to the same width W5 as the first area 221a. In other
words, both ends of the second area 221b in the track width
direction are inclined at a certain spread angle .theta. with
respect to the Y axis in the figure.
[0094] Moreover, a magnetic medium-facing surface A side end of the
magnetic pole rear part 132 is located a distance H3 forward of a
magnetic medium-facing surface A side end of the yoke front part
221. On the other hand, the yoke rear part 221 and the magnetic
pole rear part 132 have aligned ends on the side remote from the
magnetic medium-facing surface A in the height direction (along the
Y axis). However, whether these ends should be aligned or not
should be determined depending on the design.
[0095] The magnetic head according to the present invention
comprises the main magnetic pole layer 13 capable of generating a
magnetic flux .phi. of a recording magnetic field, the yoke layer
22 laid on the main magnetic pole layer 13, and the return path
magnetic pole layer 20 connected to the yoke rear part 222 in such
a manner as to return the magnetic flux .phi. of the recording
magnetic field to the main magnetic pole layer 13. Thus, they
constitute a magnetic circuit having a path through which the
magnetic flux .phi. of the recording magnetic field goes back to
the return path magnetic pole layer 20, from the main magnetic pole
layer 13, through the external magnetic recording medium M and then
goes back to the main magnetic pole layer 13 through the yoke layer
22.
[0096] The yoke rear part 222 in the present embodiment has the
same constant width W4 in the track width direction as the magnetic
pole rear part 132, favorably acting to direct magnetic fluxes f00
to f02 of the magnetic pole rear part 132 uniformly toward the
magnetic pole front part 131. However, it goes without saying that
even if the width W4 of the pole rear part 132 is not constant,
such an effect can be produced to some degree.
[0097] Since the width W1, W2 of the magnetic pole front part 131
in the track width direction is smaller than that of the magnetic
pole rear part 132 and decreases toward the magnetic medium-facing
surface A, magnetic fluxes f20 to f22 from the magnetic pole rear
part 132 can be concentrated toward the end face 13c on the
magnetic medium-facing surface A side. This increases the strength
of a recording magnetic field flowing from the magnetic
medium-facing surface A to the magnetic recording medium M, thereby
improving magnetic saturation characteristics.
[0098] In the vicinity of the magnetic medium-facing surface A,
moreover, since the width W5 of the yoke front part 221 in the
track width direction is larger than that of the magnetic pole rear
part 132 and that of the yoke rear part 222, a part f11 and f12 of
magnetic fluxes f10 to f12 flowing from the magnetic pole rear part
132 to the magnetic pole front part 131 can be dispersed toward
both ends in the track width direction or the vicinity thereof.
Thus, at the magnetic pole front part 131, the magnetic fluxes f20
to f22 can be prevented from excessively concentrating on the end
face 13c on the magnetic medium-facing surface side.
[0099] Therefore, the magnetic head according to the present
invention can reduce the strength of a recording magnetic field to
be applied to tracks adjacent to a target track for writing. This
can clearly be understood by comparing the magnetic head according
to the present invention with a conventional magnetic head.
[0100] FIG. 7 is a plan view of a main magnetic pole layer and a
yoke layer of a conventional magnetic head as seen from a
lamination plane. A main magnetic pole layer 24 of the conventional
magnetic head has substantially the same structure as the foregoing
main magnetic pole layer 13. That is, the main magnetic pole layer
24 includes a magnetic pole rear part 242 having a constant width
W4 in the track width direction and a magnetic pole front part 241
having a width W2 in the track width direction which decreases
toward the magnetic medium-facing surface A. On the other hand, a
yoke layer 26 of the conventional magnetic head has a constant
width W4 in the track width direction unlike the present
invention.
[0101] In the conventional magnetic head, magnetic fluxes f50 to
f52 in the magnetic pole rear part 152 are uniformly directed
toward the magnetic pole front part 151 without being dispersed.
Therefore, magnetic fluxes f60 to f62 in the magnetic pole front
part 151 are excessively concentrated on a pole tip 150a, thereby
increasing the risk of WATE, as described above. In fact, as a
result of the magnetic field analysis performed by the present
inventors, remarkable magnetic saturation of the trailing shield
and the leading shield has been observed in the conventional
magnetic head. On the other hand, such magnetic saturation could
not have been observed in the magnetic head according to the
present invention.
[0102] Next will be described characteristics of the magnetic head
according to the present invention in comparison with
characteristics of a conventional magnetic head. FIG. 8 is a
characteristic graph of a write magnetic field strength Hy(Oe) with
respect to a write current Iw(mA), comparing the magnetic head
according to the present invention with the conventional magnetic
head. On the other hand, FIG. 9 is a characteristic graph of a
write magnetic field strength Heff(Oe) with respect to a distance
x(.mu.m) from a target track for writing, comparing the magnetic
head according to the present invention with the conventional
magnetic head.
[0103] Dimensions of the magnetic head (see FIG. 6) according to
the present invention and used for such characteristic analyses
were as follows. [0104] The recording track width W1=70 (nm) [0105]
The width W2 of the rear end of the magnetic pole front part
131=2.2 (.mu.m) [0106] The width W4 of the magnetic pole rear part
132 and the yoke rear part 222=6 (.mu.m) [0107] The width W5 of the
yoke front part 221=11 (.mu.m) [0108] The overall length H1 of the
yoke layer 22=8 (.mu.m) [0109] The length H2 of the yoke front part
221=4.7 (.mu.m) [0110] The distance H3 between the end of the yoke
front part 221 and the end of the magnetic pole rear part 132=0.4
(.mu.m) [0111] The length H4 of the magnetic pole front part
131=1.7 (.mu.m) [0112] The spread angle .theta. of the yoke front
part 221=60 (deg.)
[0113] The conventional magnetic head is represented by a
comparative example 1 (EXAMPLE 1) in which the width W4 of the
magnetic pole rear part 152 and the yoke layer 140 was set at 20
(.mu.m) and a comparative example 2 (EXAMPLE 2) in which the width
W4 was set at 6 (.mu.m). The other dimensions of the comparative
examples 1, 2 were the same as those of the magnetic head according
to the present invention. In the figures, measurement results are
represented by diamond marks (.diamond-solid.), rectangular marks
(.box-solid.), and triangular marks (.tangle-solidup.) for the
comparative example 1, the comparative example 2, and the magnetic
head according to the present invention, respectively.
[0114] As understood from FIG. 8, the magnetic head according to
the present invention and the magnetic head of the comparative
example 2 always had a higher magnetic field strength in a low
current range than that of the comparative example 1. This shows
that the magnetic saturation characteristics of the magnetic head
with respect to the write current can be improved by reducing the
width, as described above.
[0115] A remarkable effect of the present invention can be found in
the WATE characteristics shown in FIG. 9. As understood from the
figure, the magnetic head of the comparative example 2 had a higher
strength of a recording magnetic field to be applied to tracks
adjacent to a target track for writing than that of the comparative
example 1. This shows that reducing the width W4 of the magnetic
head improves the magnetic saturation characteristics with respect
to the write current but increases the risk of WATE, as described
above.
[0116] On the other hand, the magnetic head according to the
present invention had as low a magnetic field strength as that of
the comparative example 1. Of course, this comes from the
characteristic shape of the yoke layer 22 thus far described.
[0117] Next will be described how the above characteristics can be
affected by the dimensions of the yoke layer 22. FIG. 10 is a
characteristic graph of a write magnetic field strength Hy(Oe) with
respect to a write current Iw(mA) when the spread angle .theta. was
varied. FIG. 11 is a characteristic graph of a write magnetic field
strength Heff(Oe) with respect to a distance x(.mu.m) from a target
track when the spread angle .theta. was varied.
[0118] Here, the spread angle .theta. was set at 30 (deg.), 45
(deg.), 90 (deg.), and 135 (deg.), for example. The other
dimensions had the same values as described above.
[0119] As understood from these figures, the characteristics were
not affected by varying the spread angle .theta.. Presumably, this
is because the characteristics are dominantly affected by the width
W5 of the yoke front part 221. Therefore, for example, the yoke
layer 22 may have a simpler form as shown in FIG. 12 by setting the
spread angle .theta. at 90 (deg.). In this case, the width of a
yoke front part 223 in the track width direction has a constant
value W5.
[0120] Next, FIGS. 13 and 14 show the above characteristics when
the length H2 of the yoke front part 221 was set at different
values of 1 (.mu.m), 1 (.mu.m), 5 (.mu.m), and 7 (.mu.m). Here, the
spread angle .theta. was 90 (deg.), and the other dimensions had
the same values as described above.
[0121] As understood from FIG. 13, the characteristics of the write
magnetic field strength with respect to the write current were not
affected by varying the length H2. However, as understood from FIG.
14, the magnetic field strength to adjacent tracks was increased
when the length H2 was 1 (.mu.m). Therefore, preferably, the length
H2 of the yoke front part 221 is from 2 to 7 (.mu.m). Thus, the
preferred range of a ratio of the overall length of the yoke layer
22 to the length of the yoke rear part 222 in the height direction
(along the Y axis), i.e., H1:H2 is from 8:2 to 8:7.
[0122] Next, FIGS. 15 and 16 show the above characteristics when
the common width W4 of the yoke rear part 222 and the magnetic pole
rear part 132 was set at different values of 3 (.mu.m), 4 (.mu.m),
and 6 (.mu.m). Here, the spread angle .theta. was 90 (deg.), and
the other dimensions had the same values as described above.
[0123] As understood from FIG. 15, the characteristics of the write
magnetic field strength with respect to the write current were not
affected by varying the width W4. However, as understood from FIG.
16, the magnetic field strength to adjacent tracks was increased
when the width W4 was 3 (.mu.m). Therefore, preferably, the width
W4 of the yoke rear part 221 and the magnetic pole rear part 132 is
from 4 to 6 (.mu.m). Thus, the preferred range of a width ratio of
the yoke rear part 222 to the yoke front part 221, i.e., W4:W5 is
from 6:11 to 4:11.
[0124] Next, FIGS. 17 and 18 show the above characteristics when
the width W5 of the yoke front part 221 was set at different values
of 7 (.mu.m), 9 (.mu.m), 11 (.mu.m), 13 (.mu.m), and 14 (.mu.m).
Here, the spread angle .theta. was 90 (deg.), and the other
dimensions had the same values as described above.
[0125] As understood from FIG. 17, the write magnetic field
strength was decreased in a low current range when the width W5 was
14 (.mu.m). As also understood from FIG. 18, the magnetic field
strength to adjacent tracks was increased when the width W5 was 7
(.mu.m) and 9 (.mu.m). Thus, the preferred range of the width ratio
of the yoke rear part 222 to the yoke front part 221, i.e., W4:W5
is from 6:11 to 6:13.
[0126] Taking the above results from FIGS. 15 and 16 into
consideration, accordingly, the preferred range of the width ratio
of the yoke rear part 222 to the yoke front part 221, i.e., W4:W5
is from 6:11 to 6:13. It should be noted that the optimum ratios
and values thus far described may vary depending on variation in
magnetic saturation characteristics along with variation in the
width of the main magnetic pole or the like.
[0127] In the embodiment thus far described, the yoke rear part 222
has a constant width W4 in the track width direction, but the
present invention is not limited thereto. FIGS. 19 and 20 show
embodiments in which the width of a yoke rear part 224, 225 is not
constant. Here, the shape of the yoke front part 221 and the shape
of the main magnetic pole 13 are the same as shown in FIG. 6 and
their explanations are omitted.
[0128] At first, the yoke rear part 224 shown in FIG. 19 includes a
first area 224a having a constant width W4 and a second area 224b
having a partially cut-off oval shape. The second area 224b is
connected to the first area 224a at its cut-off section. Here, the
width W5 of the yoke front part 221 is larger than the width of the
magnetic pole rear part 132 and the maximum width of the second
area 224b. Therefore, the yoke layer shown in FIG. 19 has the same
effects as that of the foregoing embodiment.
[0129] On the other hand, the yoke rear part 225 shown in FIG. 20
includes a first area 225a having a constant width W4, a second
area 225b having a trapezoidal shape whose width decreases toward
the magnetic medium-facing surface A, and a third area 225c having
a larger constant width than the first area 225a. The width of the
second area 225b decreases from the same width as the third area
225c to the same width W4 as the first area 225a. Here, the width
W5 of the yoke front part 221 is larger than the width of the
magnetic pole rear part 132 and the third area 225c. Therefore, the
yoke layer shown in FIG. 20 has the same effects as that of the
foregoing embodiment.
[0130] The advantage of thus employing the yoke rear part 224, 225
whose width in the track width direction is not constant resides in
that the shape of the yoke layer can be flexibly determined, for
example, to match the shape of the back gap GP shown in FIG. 5.
[0131] In order to obtain the same advantage, it is also possible
to employ a magnetic pole rear part 132 whose width in the track
width direction is not constant. For example, a rear area of the
magnetic pole rear part 132 as seen from the magnetic medium-facing
surface may have the same shape as the yoke rear part 224 shown in
FIG. 19 or the same shape as the yoke rear part 225 shown in FIG.
20. Also in this case, the yoke front part 221 should have a larger
width in the vicinity of the magnetic medium-facing surface A than
the magnetic pole rear part 132 so that a part of the magnetic flux
flowing from the magnetic pole rear part 132 to the magnetic pole
front part 131 can be dispersed toward both ends in the track width
direction or the vicinity thereof.
2. Method for Manufacturing Magnetic Head
[0132] Next will be described a method for manufacturing the
foregoing magnetic head HD. Processes before the production process
of the magnetic head have been known and do not require specific
description. Roughly speaking, it can be manufactured by forming
and stacking a series of components in order using a conventional
thin-film process including a film formation technique such as
plating or sputtering, a patterning technique such as
photolithography, an etching technique such as dry etching or wet
etching, and a polishing technique such as CMP (chemical mechanical
polishing).
[0133] The thin film process will be outlined with reference to
FIG. 2 and so on; when manufacturing the magnetic head, at first,
the insulating layer 2 is formed on the substrate 1, and then the
lower read shield film 3, the shield gap film 4 embedded with the
reproducing element S, and the upper read shield film 5 are stacked
on the insulating layer 2 in the mentioned order, thereby forming
the reproducing head R.
[0134] Subsequently, the separating layer 6 is formed on the
reproducing head R, and then the magnetic layer 7, the insulating
layers 8, 9, the thin film coil 10a, the leading shield layer 23,
the insulating layers 11, 12, the main magnetic pole layer 13, the
non-magnetic layer 14, the insulating layer 17, the trailing gap
layer 16, the second magnetic layer 27, the trailing shield layer
15, the yoke layer 22, the insulating layer 18, the thin film coil
10a, the insulating layer 19, and the return path magnetic pole
layer 20 are stacked on the separating layer 6 in the mentioned
order, thereby forming the recording head W. Finally, the overcoat
film 21 is formed on the recording head W, and then the air bearing
surface A is formed by using a machining process or a polishing
process, thereby completing the magnetic head.
[0135] In the above-described production process of the magnetic
head, the process of forming the main magnetic pole layer 13 and
the yoke layer 22 will be described in detail. FIGS. 21(a) to 21(m)
illustrate events of a formation process of the main magnetic pole
layer 13 in a front view of the recording medium-facing surface
A.
[0136] First of all, as shown in FIG. 21(a), the magnetic layer 7
and the insulating layers 8, 11, 12 are stacked in the named
order.
[0137] Then, a tapered face is formed in the insulating layer 12 in
order to obtain a mold for forming the second tapered face 13b of
the main magnetic pole layer 13. This event is illustrated in FIG.
22(a) as an enlarged sectional view taken along the Y-Z plane. As
illustrated, the insulating layer 12 is etched by ion milling down
to a position indicated by a dotted line. Ion milling is performed
by irradiating ion beam IB at a certain angle while oscillating the
substrate. Thus, a tapered face 12a is formed in a front area of
the upper surface of the insulating layer 12 to reduce a layer
thickness rearward.
[0138] Then, as shown in FIG. 21(b), a resist pattern 33 having a
recess 150 is formed on the insulating layer 12. When forming the
resist pattern 33, a resist film is formed by applying a resist to
the surface of the insulating layer 12, and then the resist film is
subjected to patterning (exposure and development) by using a
photolithography process.
[0139] At this time, exposure conditions are adjusted such that the
recess 150 spreads with distance from the insulating layer 12 and
an inclination angle .omega. of an inner wall with respect to the
surface of the insulating layer 12 is equal to a bevel angle of the
pole tip 13c having an inverted trapezoid shape (an exterior angle
of the inverted trapezoid shape at the bottom side).
[0140] On the other hand, as seen from the lamination plane (X-Y
plane), the resist pattern 33 has a shape shown in FIG. 23(a). In
order to match the above-described shape of the main magnetic pole
layer 13, accordingly, the resist pattern 33 has an inner wall
surface 332 forming a rectangular space which has a constant width
in the track width direction and an inner wall surface 331
extending in front of the inner wall surface 332 and forming a
generally triangular space whose width decreases toward the
magnetic medium-facing surface.
[0141] After formation of the resist pattern 33, as shown in FIG.
21(c), a non-magnetic film 120 having a uniform film thickness is
formed by deposition, using an ALD process or a CVD process, in
such a manner as to cover at least the inner wall surface of the
resist pattern 33 within the recess 150. At this time, the film
thickness of the non-magnetic film 120 is adjusted so as to obtain
the above-described pole width W1.
[0142] Then, as shown in FIG. 21(d), the tip portion 13c of the
main magnetic pole layer 13 is formed within the recess 150 by
using an electroplating process or the like. In this case, for
example, after formation of a seed layer (not shown), the seed
layer is used as an electrode film to grow a plated film. However,
it is also possible to use a sputtering process instead of an
electroplating process.
[0143] Then, using a milling process or a CMP process, the surface
is polished down to a position indicated by a dotted line in the
figure. With this, as shown in FIG. 21(e), the resist pattern 33 is
exposed at both sides of the tip portion 13c.
[0144] Subsequently, as shown in FIG. 21(f), the resist pattern 33
is removed, for example, by a cleaning process with an organic
solvent or an ashing process to expose both side faces of the tip
portion 13c, and then the insulating layers 11, 12 are selectively
removed at an area overlapping with the tip portion 13c in the
thickness direction (Z direction) and at both side areas thereof.
Concretely, the insulating layers 8, 11, 12 are all removed from an
area of the width W3 with the tip portion 13c centered in the
recording track width direction (X direction). Here, if the
insulating layers 8, 11, 12 are made of alumina, for example, they
can be dissolved and removed by using a given solvent (for example,
an alkaline solution). This results in exposing not only the
surface of the magnetic layer 7 but also the peripheral surface of
the tip portion 13c.
[0145] After removal of the insulating layers 8, 11, 12 from an
area in the vicinity of the tip portion 13c, an insulating material
such as alumina is deposited to surround the tip portion 13c by
using a CVD process or an ALD process, as shown in FIG. 21(g). This
provides the side gaps 121 and an insulating film 122 including the
insulating layer 12 as a leading gap. At this time, the insulating
material is also deposited on the surface of the magnetic layer 7
to reform the insulating layer 8.
[0146] Subsequently, as shown in FIG. 21(h), a magnetic layer 231
is formed by using an electroplating process or the like to cover
the whole and completely bury the tip portion 13c and the
insulating film 122. Of the magnetic layer 231, a portion located
on the leading side as seen from the insulating layer 12 (a portion
located adjacent to the insulating layer 8) becomes the leading
shield 23.
[0147] In addition, using a milling process or a CMP process, the
surface is polished down to a position indicated by a dotted line
in the figure. With this, the tip portion 13c is exposed and the
side shields 25 are formed, as shown in FIG. 21(i). At this time,
excessive polishing may be performed on demand in order to ensure
the exposure of the tip portion 13c.
[0148] The main magnetic pole layer 13 thus formed is laid on the
insulating layer 12 with the pole tip 13c exposed on the magnetic
medium-facing surface A, as shown in FIG. 22(b) as an enlarged
sectional view taken along the Y-Z plane. Here, the above-described
second tapered face 13b is formed to extend from the leading edge
LE of the pole tip 13c along the tapered face 12a of the insulating
film 120 shown in FIG. 22(a).
[0149] Next will be described a formation process of the tapered
face 13a, 14a with reference to FIGS. 22(c) and 22(d), which are
similar enlarged sectional views.
[0150] After formation of the main magnetic pole layer 13, the
non-magnetic layer 14 is formed by a known technique such as
sputtering to be laid on the main magnetic pole layer 13, as shown
in FIG. 22(c).
[0151] Moreover, as shown in FIG. 22(d), a resist pattern 30 as a
mask for forming the tapered face 13a, 14a is formed on the
non-magnetic layer 14 by a photolithography process. A thickness of
the resist pattern 30 or the like is properly set depending on the
intended tapered face 13a, 14a.
[0152] Then, the main magnetic pole layer 13 and the non-magnetic
layer 14 are etched by ion milling down to a position indicated by
a dotted line. Ion milling is performed by irradiating ion beam IB
at a certain angle while fixing the substrate. After completion of
the etching process, the resist pattern 30 is removed.
[0153] Thus, the tapered face 13a, 14a is formed to extend from the
trailing edge TE of the pole tip 13c, continue from the main
magnetic pole layer 13 to the non-magnetic layer 14, and have a
constant inclination angle. It should be noted that although
ruthenium may be taken as a typical example of the non-magnetic
layer 14, as described above, other materials may also be employed
as long as having a milling rate close to that of the main magnetic
pole layer 13.
[0154] Subsequently, as shown in FIGS. 21(j) and 22(e), the
trailing gap layer 16 and the second magnetic layer 27 are formed
by a known technique such as sputtering to be laid over the main
magnetic pole layer 13 and the non-magnetic layer 14, covering the
tapered face 13a, 14a and a front portion of a flat face 14b of the
non-magnetic layer 14.
[0155] Then, as shown in FIG. 21(k), a resist pattern 161 is formed
by a photolithography process in the vicinity of the upper side of
the tip portion 13c of the main magnetic pole layer 13. Then, the
trailing gap layer 16 and the second magnetic layer 27 are etched
and removed by ion milling except the portion in the vicinity of
the upper side of the tip portion 13c. Ion milling is performed by
irradiating ion beam IB from above. After completion of the etching
process, the resist pattern 161 is removed.
[0156] Thus, as shown in FIG. 21(l), there is obtained a layer
structure where the trailing gap layer 16 and the second magnetic
layer 27 are present only in the vicinity of the upper side of the
tip portion 13c as seen from the magnetic medium-facing surface
A.
[0157] Thereafter, as shown in FIGS. 21(m) and 22(f), the trailing
shield layer 15, which is to be exposed on the magnetic
medium-facing surface A, is formed by using a plating process or
the like to be laid over the main magnetic pole layer 13 and the
non-magnetic layer 14 with the trailing gap layer 16 and the second
magnetic layer 27 in between.
[0158] Then, the yoke layer 22 is formed behind the non-magnetic
layer 14, and the space between it and the trailing shield layer 15
is filled with the insulating layer 17, and the surface is polished
by a CMP process.
[0159] FIG. 23(b) shows the shape of a resist pattern 34 for
forming the yoke layer 22 as seen from the lamination plane (X-Y
plane). In order to match the shape of the yoke layer 22 shown in
FIG. 6, the resist pattern 34 has an inner wall surface 333 forming
a rectangular space which has a constant width in the track width
direction, an inner wall surface 332 extending in front of the
inner wall surface 333 and forming a trapezoidal space whose width
increases toward the magnetic medium-facing surface, and an inner
wall surface 331 forming a rectangular space which has a constant
width in the track width direction. However, it goes without saying
that the resist pattern 34 is not limited to such a shape but may
be formed in accordance with the design, for example, to match the
shape of the yoke layer 22 shown in FIG. 12.
[0160] Through the process thus far described, there is obtained
the structure around the main magnetic pole layer 13 and the yoke
layer 22 of the magnetic head shown in FIG. 2.
3. Head Assembly
[0161] Next will be described a head assembly according to the
present invention. The head assembly according to the present
invention includes the above-described magnetic head and a head
support device. The head support device supports the magnetic head
in such a manner as to permit rolling and pitching of the magnetic
head. In the present invention, examples of the head assembly
include an HGA (head gimbal assembly) in which the magnetic head is
mounted on a head support device (gimbal) and an HAA (head arm
assembly) in which the HGA is mounted on an arm.
[0162] FIG. 24 is a top view of a head assembly according to the
present invention, and FIG. 25 is a bottom view of the head
assembly shown in FIG. 24. The head assembly is an HGA including a
suspension 203 and the magnetic head HD. The suspension 203
includes a load beam 211 and a flexure 202. The load beam 211 has a
load dimple 217 in proximity to a free end on a centrally-extending
longitudinal axis.
[0163] The flexure 202 is formed from a thin leaf spring and
subjected to a pressing load from the load dimple 217 with one side
thereof attached to one side of the load beam 211 where the load
dimple 217 is located. The magnetic head HD is attached to the
other side of the flexure 202. The flexure 202 is bonded to the
load beam 211 at the side where the load dimple 217 is located.
[0164] The flexure 202 has a tongue portion 212 in the center
thereof. At one end, the tongue portion 212 is bonded to a lateral
frame portion 213 of the flexure 202. Both ends of the lateral
frame portion 213 of the flexure 202 are connected to outer frame
portions 215, 216. A groove 214 is formed between the tongue
portion 212 and the outer frame portions 215, 216, extending around
the tongue portion 212. The magnetic head HD is attached to one
side of the tongue portion 212 by means of an adhesive or the like,
which is kept in spring contact with the tip of the load dimple
217.
[0165] One face of the magnetic head HD opposite from the air
bearing surface of the slider is attached to the tongue portion 212
of the suspension 203. Flexible leads and so on not shown in the
drawings are connected to the magnetic head HD.
[0166] FIG. 26 is a front view of an HAA. The HAA includes the
suspension 203, the magnetic head HD and an arm 204. The arm 204 is
integrally formed from a suitable non-magnetic metallic material
such as aluminum alloy. The arm 204 is provided with a mounting
hole. The mounting hole is used for mounting on a positioning
device provided in a magnetic disk apparatus. One end of the
suspension 203 is secured to the arm 204, for example, with a ball
connecting structure.
[0167] Since the head assembly includes the magnetic head according
to the present invention, it also has the same effects.
4. Magnetic Recording/Reproducing Apparatus
[0168] Finally, a magnetic recording/reproducing apparatus
according to the present invention will be described. FIG. 27 is a
perspective view of the magnetic recording/reproducing apparatus.
In FIG. 27, a case 200 is partially cut out, making it easy to see
the internal structure of the apparatus.
[0169] This magnetic recording/reproducing apparatus is equipped
with the above head assembly, and in the present embodiment, a hard
disk drive is taken as an example for explanation. The magnetic
recording/reproducing apparatus includes, within the case 200, a
plurality of magnetic disks (i.e., hard disks) 201 corresponding to
the magnetic recording medium M, on which information is to be
magnetically recorded, a plurality of suspensions 203 disposed
corresponding to the respective magnetic disks 201 and supporting
the magnetic heads HD at their one ends, and a plurality of arms
204 supporting the other ends of the suspensions 203.
[0170] When the magnetic disk 201 rotates for recording or
reproducing information, the magnetic head HD takes off from the
recording surface of the magnetic disk 201 utilizing an airflow
generated between the recording surface (magnetic head-facing
surface) of the magnetic disk 201 and the air bearing surface
A.
[0171] The magnetic disks 201 are rotatable about a spindle motor
205 which is fixed to the case 200. The arms 204 are connected to
an actuator 206 being a power source and are pivotable through a
bearing 208 about a fixed shaft 207 which is fixed to the case 200.
The actuator 206 is constructed to include, for example, a driving
source such as a voice coil motor.
[0172] Using the head assembly equipped with the magnetic head, as
has been described above, the magnetic recording/reproducing
apparatus records information on the magnetic disk 201 by applying
a recording magnetic field and reproducing information from the
magnetic disk. Thus, the magnetic recording/reproducing apparatus
has the same effects as the magnetic head according to the present
invention.
[0173] The present invention has been described in detail above
with reference to preferred embodiments. However, obviously those
skilled in the art could easily devise various modifications of the
invention based on the technical concepts underlying the invention
and teachings disclosed herein.
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