U.S. patent application number 15/199775 was filed with the patent office on 2016-10-27 for onset layer for perpendicular magnetic recording media.
The applicant listed for this patent is HGST Netherlands B.V.. Invention is credited to Xiaoping Bian, Jack Jyh-Kau Chang, Mark F. Mercado, Mohammad T. Mirzamaani, Kai Tang.
Application Number | 20160314811 15/199775 |
Document ID | / |
Family ID | 44142622 |
Filed Date | 2016-10-27 |
United States Patent
Application |
20160314811 |
Kind Code |
A1 |
Bian; Xiaoping ; et
al. |
October 27, 2016 |
ONSET LAYER FOR PERPENDICULAR MAGNETIC RECORDING MEDIA
Abstract
A magnetic storage medium according to one embodiment includes a
substrate; an onset layer formed above the substrate, the onset
layer comprising ruthenium and titanium oxide; and a magnetic oxide
layer formed directly on the onset layer. The onset layer is formed
directly on a ruthenium underlayer stack having at least one layer
of ruthenium formed under a relatively higher pressure and at least
one layer of ruthenium formed under a relatively low pressure. A
method according to one embodiment includes sputtering using a
target of ruthenium and titanium oxide for forming an onset layer
above a substrate, the onset layer comprising ruthenium and
titanium oxide; and forming a magnetic oxide layer directly on the
onset layer. Additional systems and methods are also presented.
Inventors: |
Bian; Xiaoping; (Saratoga,
CA) ; Chang; Jack Jyh-Kau; (Fremont, CA) ;
Mercado; Mark F.; (Morgan Hill, CA) ; Mirzamaani;
Mohammad T.; (San Jose, CA) ; Tang; Kai; (San
Jose, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HGST Netherlands B.V. |
Amsterdam |
|
NL |
|
|
Family ID: |
44142622 |
Appl. No.: |
15/199775 |
Filed: |
June 30, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12638894 |
Dec 15, 2009 |
9412404 |
|
|
15199775 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C23C 14/3414 20130101;
C23C 14/083 20130101; G11B 5/851 20130101; C23C 14/0688 20130101;
C23C 14/34 20130101; G11B 5/65 20130101; G11B 5/7325 20130101; G11B
5/8404 20130101 |
International
Class: |
G11B 5/851 20060101
G11B005/851; C23C 14/34 20060101 C23C014/34; C23C 14/08 20060101
C23C014/08; G11B 5/65 20060101 G11B005/65 |
Claims
1. A magnetic storage medium, comprising: a substrate; an onset
layer formed above the substrate, the onset layer comprising
ruthenium and titanium oxide, wherein a deposition thickness of the
onset layer is between about 2 angstroms and about 8 angstroms,
wherein a titanium oxide concentration in the onset layer is
between about 4.0 molecular % and about 12 molecular %; and a
magnetic oxide layer formed directly on the onset layer, wherein
the onset layer is formed directly on a ruthenium underlayer stack
having at least one layer of ruthenium formed under a relatively
higher pressure and at least one layer of ruthenium formed under
pressure.
2. The medium as recited in claim 1, wherein an oxygen
concentration in a sputter chamber during formation of the onset
layer is between about 0.01 vol % and about 0.5 vol %.
3. A method, comprising: sputtering using a target of ruthenium and
titanium oxide for forming an onset layer above a substrate, the
onset layer comprising ruthenium and titanium oxide; and forming a
magnetic oxide layer directly on the onset layer.
4. The method as recited in claim 3, wherein oxygen and an inert
gas are flowed into sputtering chamber during the sputtering,
wherein a volumetric flow rate of the oxygen is between about 1%
and about 4% of a total volumetric flow rate of the oxygen and
inert gas.
5. The method as recited in claim 3, wherein oxygen is not flowed
into a sputtering chamber during formation of any other layers
formed by sputtering.
6. The method as recited in claim 3, wherein the target comprises
less than about 8 atomic % ruthenium.
7. The method as recited in claim 3, wherein a deposition thickness
of the onset layer is between about 5.0 angstroms and about 10
angstroms.
8. The method as recited in claim 3, wherein a deposition thickness
of the onset layer is about 7.0 angstroms.
9. The method as recited in claim 3, wherein a titanium oxide
concentration in the onset layer is between about 4.0 molecular %
and about 12 molecular %.
10. The method as recited in claim 3, wherein: a titanium
concentration in the onset layer is between about 1.5 atomic % and
about 4.0 atomic %, and an oxygen concentration in the onset layer
is between about 3.0 atomic % and about 8.0 atomic %.
Description
FIELD Of THE INVENTION
[0001] The present invention relates to magnetic media, and more
particular, this invention relates to a magnetic medium having an
onset layer.
BACKGROUND
[0002] Developments have been made in the area of perpendicular
magnetic recording media, with much of them focusing on increasing
the recording density of the magnetic recording media by decreasing
the bit error rate. A lower bit error rate can be achieved by
decreasing the transition noise between adjacent bits, and the
transition noise in turn can be decreased by increasing the
magnetic decoupling between grains. Grains that are decoupled and
magnetically isolated from one another can switch independently and
may allow the media to form finer and narrower transitions.
Therefore, it would be beneficial to the improvement of
perpendicular recording media to magnetically decouple the magnetic
grains of the magnetic layer of a magnetic recording medium.
SUMMARY
[0003] A magnetic storage medium according to one embodiment
includes a substrate; an onset layer formed above the substrate,
the onset layer comprising ruthenium and titanium oxide. A
deposition thickness of the onset layer is between about 2
angstroms and about 8 angstroms. A titanium oxide concentration in
the onset layer is between about 4.0 molecular % and about 12
molecular %. A magnetic oxide layer is formed directly on the onset
layer. The onset layer is formed directly on a ruthenium underlayer
stack having at least one layer of ruthenium formed under a
relatively higher pressure and at least one layer of ruthenium
formed under a relatively lower pressure.
[0004] A method according to one embodiment includes sputtering
using a target of ruthenium and titanium oxide for forming an onset
layer above a substrate, the onset layer comprising ruthenium and
titanium oxide; and forming a magnetic oxide layer directly on the
onset layer.
[0005] Any of these embodiments may be implemented in or for a
magnetic data storage system such as a disk drive system, which may
include a magnetic head, a drive mechanism for passing a magnetic
medium (e.g., hard disk) over the magnetic head, and a controller
electrically coupled to the magnetic head.
[0006] Other aspects and advantages of the present invention will
become apparent from the following detailed description, which,
when taken in conjunction with the drawings, illustrate by way of
example the principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] For a fuller understanding of the nature and advantages of
the present invention, as well as the preferred mode of use,
reference should be made to the following detailed description read
in conjunction with the accompanying drawings.
[0008] FIG. 1 is a simplified drawing of a magnetic recording disk
drive system.
[0009] FIG. 2 is a schematic representation of layers of a magnetic
storage medium, according to one embodiment.
[0010] FIG. 3 is a flowchart showing a method according to one
embodiment.
DETAILED DESCRIPTION
[0011] The following description is made for the purpose of
illustrating the general principles of the present invention and is
not meant to limit the inventive concepts claimed herein. Further,
particular features described herein can be used in combination
with other described features in each of the various possible
combinations and permutations.
[0012] Unless otherwise specifically defined herein, all terms are
to be given their broadest possible interpretation including
meanings implied from the specification as well as meanings
understood by those skilled in the art and/or as defined in
dictionaries, treatises, etc.
[0013] It must also be noted that, as used in the specification and
the appended claims, the singular forms "a," "an" "and" the include
plural referents unless otherwise specified.
[0014] The following description discloses several preferred
embodiments of disk-based storage systems and/or related systems
and methods, as well as operation and/or component parts
thereof.
[0015] In one general embodiment, a magnetic storage medium
comprises a substrate; an onset layer formed above the substrate,
the onset layer comprising ruthenium and titanium oxide; and a
magnetic oxide layer formed directly on the onset layer.
[0016] In another general embodiment, a magnetic storage medium
comprises a substrate; an onset layer formed above the substrate,
the onset layer comprising ruthenium and titanium oxide, wherein a
deposition thickness of the onset layer is between about 2
angstroms and about 8 angstroms, wherein a titanium oxide
concentration in the onset layer is between about 4 molecular % and
about 12 molecular %; and a magnetic oxide layer formed directly,
on the onset layer. The onset layer is formed directly on a
ruthenium underlayer stack having at least one layer of ruthenium
formed under a relatively higher pressure and at least one layer of
ruthenium formed under a relatively lower pressure. In a version of
this embodiment, the onset layer causes the medium to exhibit an at
least 0.2 orders of magnitude lower bit error a than an otherwise
identical magnetic storage medium not having the onset layer.
[0017] In another general embodiment, a method comprises sputtering
using a target of ruthenium and titanium oxide for forming an onset
layer above a substrate, the onset layer comprising ruthenium and
titanium oxide; and forming a magnetic oxide layer directly on the
onset layer.
[0018] In yet another general embodiment, a system includes a
magnetic storage medium, at least one head for reading from and/or
writing to the magnetic medium, a slider for supporting the at
least on head, and a control unit coupled to the at least one head
for controlling operation of the at least one head. The magnetic
storage medium comprises a substrate, an onset layer comprising
ruthenium and titanium oxide formed above the substrate, and a
magnetic oxide layer formed directly on the onset layer.
[0019] Referring now to FIG. 1, there is shown a disk drive 100 in
accordance with one embodiment of the present. As shown in FIG. 1,
at least one rotatable magnetic disk 112 is supported on a spindle
114 and rotated by a disk drive motor 118. The magnetic recording
on each disk is typically in the form of an annular pattern of
concentric data tracks (not shown) on the disk 112.
[0020] At least one slider 113 is positioned near the disk 112,
each slider 113 supporting one or more magnetic read/write heads
121. As the disk rotates, slider 113 is moved radially in and out
over disk surface 122 so that heads 121 may access different tracks
of the disk where desired data are recorded and/or to be written.
Each slider 113 is attached to an actuator arm 119 by means of a
suspension 115. The suspension 115 provides a slight spring force
which biases slider 113 against the disk surface 122. Each actuator
arm 119 is attached to an actuator 127. The actuator 127 as shown
in FIG. 1 may be a voice coil motor (VCM). The VCM comprises a coil
movable within a fixed magnetic field, the direction and speed of
the coil movements being controlled by the motor current signals
supplied by cont oiler 129.
[0021] During operation of the disk storage system, the rotation of
disk 112 generates an air bearing between slider 113 and disk
surface 122 which exerts an upward force or lift on the slider. The
air bearing thus counter-balances the slight spring force of
suspension 115 and supports slide 113 off and slightly above the
disk surface by a s , substantially constant spacing during normal
operation. Note that in some embodiments, the slider 113 may slide
along the disk surface 122.
[0022] The various components of the disk storage system are con
led in operation by control signals generated by control unit 129,
such as access control signals and internal clock signals.
Typically, control unit 129 comprises logic control circuits,
storage (e.g., memory), and a microprocessor. The control unit 129
generates control signals to control various system operations such
as drive motor control signals on line 123 and head position and
seek control signals on line 128. The control signals on line 128
provide the desired current profiles to optimally move and position
slider 113 to the desired data track on disk 112. Read and write
signals are communicated to and from read/write heads 121 by way of
recording channel 125.
[0023] The above description of a typical magnetic disk storage
system, and the accompanying illustration of FIG. 1 is for
representation purposes only. It should be apparent that disk
storage systems may contain a large number of disks and actuators,
and each actuator may support a number of sliders.
[0024] An interface may also be provided for communication between
the disk drive and a host (integral or external) to send and
receive the data and for controlling the operation of the disk
drive and communicating the status of the disk drive to the host,
all as will be understood by those of skill in the art.
[0025] In a typical head, an inductive write head includes a coil
layer embedded in one or more insulation layers (insulation stack),
the insulation stack being located between first and second pole
piece layers, A gap is formed between the first and second pole
piece layers by a gap layer at an air bearing surface (ABS) of the
write head. The pole piece layers may be connected at a back gap.
Currents are conducted through the coil layer, which produce
magnetic fields in the pole pieces. The magnetic fields fringe
across the gap at the ABS for the purpose f writing bits of
magnetic field information in tracks on moving media, such as in
circular tracks on a rotating magnetic disk.
[0026] The second pole piece layer has a pole tip portion which
extends from the ABS to a flare point and a yoke portion which
extends from the flare point to the back gap. The flare point is
where the second pole piece begins to widen (flare) to fort the
yoke. The placement of the flare point directly affects the
magnitude of the magnetic field produced to write information on
the recording medium.
[0027] It has been surprisingly found that by adding an onset layer
above a substrate and below an oxide layer of a magnetic storage
medium, such as a magnetic disk, the performance of the magnetic
storage medium can be increased.
[0028] For magnetic disks, according to some embodiments,
decoupling of the initial magnetic layer is useful for reducing the
noise of perpendicular media. In order to accomplish this
decoupling effect, an onset layer comprised of Ru and TiO2 is
introduced underneath the magnetic layer, according to some
approaches. The onset layer comprising such materials as described
previously has surprisingly been found to enhance grain decoupling
of the magnetic layer at the initial growth stage, leading to a
decreased media bit error rate and a reduction of magnetic core
width. In addition, according to some approaches, by introducing
the onset layer underneath the magnetic oxide layer, an increased
switching field distribution, SFD, may surprisingly be achieved,
indicating more decoupling of the magnetic grains. Recording
parametric measurements indicate a 0.2 to 0.4 order improvement in
bit error rate (BER) and adaptive format bit error rate (AF_BER),
with about 1 nm to about 2 nm narrower magnetic core width (MCW).
This result could not have been predicted.
[0029] Referring to Table 1 below, it can be seen that magnetic
media including an onset layer, according to one embodiment, has
better recording characteristics than current film designs with
another conventional structure. Moreover, addition of the onset
layer produced a negligible change on overwrite (OW).
TABLE-US-00001 TABLE 1 Recording Parametric Measurements Sample
Description SFD BER AF_BER MCW OW 1 Current 2425 -5.54 -5.09 80.9
-38.8 Film Design 2 Design w/ 2550 -5.75 -5.55 79.3 -36.9 Onset
Layer
[0030] Now referring to FIG. 2, in one embodiment, a magnetic
storage medium 200 (e.g., a magnetic disk in a hard disk drive
(HDD), etc.) is described. FIG. 2 is a highly simplified schematic
diagram of a cross-sectional view of a magnetic storage medium 200,
which extends in either direction horizontally from the view shown.
The magnetic storage medium 200 includes a substrate 202, an onset
layer 204 comprising ruthenium and titanium oxide formed above the
substrate 202, and a magnetic oxide layer 206 formed directly on
the onset layer 204. By directly on the onset layer 204, what is
meant is that the oxide layer 206 contacts the onset layer 204, and
may possibly be formed by oxidizing a portion of the onset layer
204, thereby producing an amount of oxidation on an outside portion
of the onset layer 204 during formation. In another approach, the
oxide layer 206 may be formed of another, distinct layer from the
onset layer 204, but is formed directly on the onset layer 204.
[0031] In some embodiments, the oxide layer 206 may be comprised of
titanium oxide, TiO.sub.x. Moreover, a second oxide layer 226 may
be formed above the oxide layer 206. Additional layers may include
an exchange control layer 228, a cap layer 230 and an optional
overcoat 232 e.g. of carbon.
[0032] Each layer shown in FIG. 2 may be formed through sputtering,
or any other technique known in the art. Each layer may have a
different composition from those described below in one
illustrative embodiment. Moreover, layers may be added and/or
removed in some embodiments. The substrate 202 may be formed of a
glass material, and may have a greater thickness than the other
layers formed thereon. The adhesion layer 208 may be comprised of
aluminum, titanium, or compositions thereof, etc., and may function
to prevent the layers formed above the substrate 202 from "peeling
off" during use. The soft underlayers 210, 214 are separated by a
ruthenium break layer 212, and may, be comprised of cobalt, iron,
tantalum, zirconium, or compositions thereof, etc., which provide a
high moment. The ruthenium break layer 212 is also referred to as
an anti-ferromagnetic coupling layer AFC). The seed layers 216, 218
may be comprised of any suitable material as would be known in the
art, such as nickel, tungsten, chromium, titanium, or combinations
thereof, etc. The underlayers 220, 222, 224 may be comprised of any
suitable material as would be known in the art, such as ruthenium,
and may be formed under different pressures, such as a lower
pressure for underlayer I, 220, and higher pressures for
underlayers II, III, 222, 224, respectively.
[0033] According to some approaches, a deposition thickness of the
onset layer 204 may be between about 2.0 .ANG. and about 20 .ANG.,
where "about X angstroms" indicates "X.+-.1.0 .ANG.." In more
approaches, a deposition thickness of the onset layer 204 may be
between 5.0 .ANG. and about 8.0 .ANG..
[0034] In more embodiments, a sputter chamber may be used to form
at least a portion of the onset layer 204. In the sputter chamber,
an oxygen concentration during formation of the onset layer 204 may
be between about 0.01 vol % and about 0.50 vol % (volume
percentage), where "about X vol %" indicates "X.+-.0.01." In
addition, at least some oxygen is present, e.g., there is not 0 vol
% oxygen in the sputter chamber during onset layer 204
formation.
[0035] According to some more approaches, a titanium oxide
concentration in the onset layer 204 may be between about 4.0
molecular % and about 12 molecular %, where "about X molecular %"
indicates "X.+-.1.0 molecular %." In more approaches, a titanium
concentration in the onset layer 204 may be between about 1.5
atomic % and about 4.0 atomic %.
[0036] In more approaches, an oxygen concentration in the onset
layer 204 may be between about 3.0 atomic % and about 8.0 atomic
%.
[0037] According to some embodiments, the onset layer 204 may be
formed directly on a ruthenium underlayer stack (e.g., underlayers
I, II, III, 220, 222, 224) having at least one layer of ruthenium
formed under a relatively higher pressure and at least one layer of
ruthenium formed under a relatively lower pressure, the pressures
being relative to each other.
[0038] In more embodiments, the onset layer 204 may cause the
magnetic storage medium 200 to exhibit an at least 0.2 order of
magnitude lower bit error rate (BER) than an otherwise identical
magnetic storage medium not having the onset layer 204 under
identical conditions, e.g., if both the present medium and the
comparative medium were written to and read by the same head under
identical operating conditions. In further embodiments, the onset
layer may cause the magnetic storage medium 200 to exhibit an at
least 0.3 order of magnitude lower BER than an otherwise identical
magnetic storage medium not having the onset layer.
[0039] According to some approaches, the onset layer 204 may cause
the medium 200 to exhibit the physical property of having a written
magnetic core width that is at least about 1 nm narrower than would
be exhibited by an otherwise identical magnetic storage medium not
having the onset layer under identical writing conditions, e.g., if
written by the same head at the same fly height.
[0040] In some approaches, a deposition thickness of the onset
layer 204 may be between about 5.0 .ANG. and about 10 .ANG.. In
addition., a titanium oxide concentration in the onset layer 204
may be between about 4.0 molecular % and about 12 molecular %, and
the onset layer 204 may cause the medium 200 to exhibit an at least
0.2 orders of magnitude lower BER than an otherwise identical
magnetic storage medium not having the onset layer.
[0041] With continued reference with FIG. 2, in another embodiment,
a magnetic storage medium 200 comprises a substrate 202, an onset
layer 204 comprising ruthenium and titanium oxide formed above the
substrate 202, and a magnetic oxide layer 206 formed directly on
the onset layer 204. A deposition thickness of the onset layer 204
is between about 2.0 .ANG. and about 8.0 .ANG., and a titanium
oxide concentration in the onset layer 204 is between about 4
molecular % and about 12 molecular %. Also, the onset layer 204 is
formed directly on a ruthenium underlayer stack (e.g., underlayer I
220, underlayer II 222, underlayer 224) having at least two layers
of ruthenium, one layer of ruthenium formed under a relatively
higher pressure and one layer of ruthenium formed under a
relatively lower pressure, the pressures being relative to each
other. In addition, the onset layer 204 causes the magnetic storage
medium 200 to exhibit an at least 0.2 orders of magnitude lower BER
than an otherwise identical magnetic storage medium not having the
onset layer under identical conditions, e.g., if both the present
medium and the comparative medium were written and read by the same
head under identical operating conditions. In some additional
approaches, the onset layer 204 may cause the medium 200 to exhibit
an at least 0.3 orders of magnitude lower BER than an otherwise
identical magnetic storage medium not having the onset layer
204.
[0042] According to some approaches, a sputter chamber may be used
to form at least a portion of the onset layer 204. In the sputter
chamber, an oxygen concentration during formation of the onset
layer 204 may be between about 0.01 vol % and about 0.50 vol %
(volume percentage), where "about X vol %" indicates "X.+-.0.01."
In addition, at least some oxygen is present , e.g., there is not 0
vol % oxygen in the sputter chamber during onset layer 204
formation.
[0043] In more approaches, the onset layer 204 may cause the
magnetic storage medium 200 to exhibit the physical property of
having a written magnetic core width that is at least 1.0 nm
narrower than would be exhibited by an otherwise identical magnetic
storage medium not having the onset layer under identical writing
conditions, e.g., if written by the same head at the same fly
height.
[0044] Now referring to FIG. 3, a method 300 is described according
to one embodiment. The method 300 may be carried out in any desired
environment, and may include aspects described in accordance with
embodiments depicted in FIGS. 1-2.
[0045] operation 302, an onset layer is formed above a substrate by
sputtering using a target of ruthenium and titanium oxide. The
onset layer comprises ruthenium and titanium oxide after the
sputtering.
[0046] In one embodiment, the target may comprise less than about 8
atomic % ruthenium relative to the total atomic percentages of all
components.
[0047] In some approaches, a sputter chamber may be used to form at
least a portion of the onset layer. In the sputter chamber, oxygen
and an inert gas are flowed during the sputtering, and a volumetric
flow rate of the oxygen is between about 1.0% and about 4.0% of a
total volumetric flow a e of the oxygen and the inert gas. For
example, in one experiment, the flowrates of oxygen and argon (as
the inert gas) were 4.0 seem and 195 sccm, respectively.
[0048] In more approaches, no oxygen may be flowed into the sputter
chamber during formation of any other layers of a magnetic storage
medium formed by the sputtering.
[0049] According to some approaches, a deposition thickness of the
onset layer may b between about 5.0 .ANG. and about 10 .ANG.,
preferably about 7.0 .ANG.. In addition, "about X atomic %"
indicates "X.+-.1.0 atomic %." According to one preferred
embodiment, a deposition thickness of the onset layer may be about
7.0 .ANG..
[0050] In some approaches, a titanium oxide concentration in the
onset layer may be between about 4.0 molecular % and about 12
molecular %, titanium between about 1.5 atomic % and about 4.0
atomic %, and oxygen between about 3 atomic % and about 8 atomic %,
etc.
[0051] In operation 304, a magnetic oxide layer is formed directly
on the onset layer. By directly on the onset layer, what is meant
is that the oxide layer contacts the onset layer, and may possibly
be formed by oxidizing a portion of the onset layer, thereby
producing an amount of oxidation on an outside portion of the onset
layer. In another approach, the oxide layer may be formed of
another, distinct layer from the onset layer, but is formed
directly above the onset layer.
[0052] According to another embodiment, a system includes a
magnetic storage medium, at least one head for reading from and/or
writing to the magnetic medium, a slider for supporting the at
least on head, and a control unit coupled to the at least one head
for controlling operation of the at least one head. The magnetic
storage medium may include any of the properties and structures as
described previously. For example, the magnetic medium may comprise
a substrate, an onset layer comprising ruthenium and titanium oxide
formed above the substrate, and a magnetic oxide layer formed
directly on the onset layer.
[0053] While various embodiments have been described above, it
should be understood that they have been presented by way of
example only, and not limitation. Thus, the breadth and scope of an
embodiment of the present invention should not be limited by any of
the above-described exemplary embodiments, but should be defined
only in accordance with the following claims and their
equivalents.
* * * * *