U.S. patent application number 16/716423 was filed with the patent office on 2020-04-16 for devices including a near field transducer (nft) with nanoparticles.
The applicant listed for this patent is Seagate Technology LLC. Invention is credited to Justin Brons, Xiaoyue Huang, Michael C. Kautzky, Steven C. Riemer, Sarbeswar Sahoo, Tong Zhao.
Application Number | 20200118587 16/716423 |
Document ID | / |
Family ID | 55912728 |
Filed Date | 2020-04-16 |
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United States Patent
Application |
20200118587 |
Kind Code |
A1 |
Zhao; Tong ; et al. |
April 16, 2020 |
DEVICES INCLUDING A NEAR FIELD TRANSDUCER (NFT) WITH
NANOPARTICLES
Abstract
Devices that include a near field transducer (NFT) including a
crystalline plasmonic material having crystal grains and grain
boundaries; and nanoparticles disposed in the crystal grains, on
the grain boundaries, or some combination thereof, wherein the
nanoparticles are oxides of, lanthanum (La), barium (Ba), strontium
(Sr), erbium (Er), hafnium (Hf), germanium (Ge), or combinations
thereof; nitrides of zirconium (Zr), niobium (Nb), or combinations
thereof; or carbides of silicon (Si), aluminum (Al), boron (B),
zirconium (Zr), tungsten (W), titanium (Ti), niobium (Nb), or
combinations thereof.
Inventors: |
Zhao; Tong; (Eden Prairie,
MN) ; Brons; Justin; (Savage, MN) ; Riemer;
Steven C.; (Minneapolis, MN) ; Kautzky; Michael
C.; (Eagan, MN) ; Huang; Xiaoyue; (Eden
Prairie, MN) ; Sahoo; Sarbeswar; (Shakopee,
MN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Seagate Technology LLC |
Cupertino |
CA |
US |
|
|
Family ID: |
55912728 |
Appl. No.: |
16/716423 |
Filed: |
December 16, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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14935753 |
Nov 9, 2015 |
10510364 |
|
|
16716423 |
|
|
|
|
62078848 |
Nov 12, 2014 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G11B 5/314 20130101;
C23C 14/0036 20130101; C23C 14/185 20130101; C23C 14/3464 20130101;
G11B 2005/0021 20130101; G11B 5/3106 20130101; C23C 16/403
20130101; C23C 16/45555 20130101; C23C 14/08 20130101; C23C 14/0641
20130101; C23C 14/0635 20130101 |
International
Class: |
G11B 5/31 20060101
G11B005/31; C23C 14/06 20060101 C23C014/06; C23C 14/08 20060101
C23C014/08; C23C 14/34 20060101 C23C014/34; C23C 14/00 20060101
C23C014/00; C23C 14/18 20060101 C23C014/18 |
Claims
1. A device comprising: a near field transducer (NFT) comprising a
crystalline plasmonic material having crystal grains and grain
boundaries; and nanoparticles disposed in the crystal grains, in
the grain boundaries, on the grain boundaries, or some combination
thereof, wherein the nanoparticles comprise: oxides of, lanthanum
(La), barium (Ba), strontium (Sr), erbium (Er), hafnium (Hf),
germanium (Ge), or combinations thereof; nitrides of zirconium
(Zr), niobium (Nb), or combinations thereof; or carbides of silicon
(Si), aluminum (Al), boron (B), zirconium (Zr), tungsten (W),
titanium (Ti), niobium (Nb), or combinations thereof.
2. The device according to claim 1, wherein the plasmonic material
comprises: gold (Au), silver (Ag), ruthenium (Ru), rhodium (Rh),
aluminum (Al), copper (Cu), or combinations thereof.
3. The device according to claim 1, wherein the plasmonic material
comprises: gold (Au), silver (Ag), aluminum (Al), copper (Cu), or
combinations thereof.
4. The device according to claim 1, wherein the nanoparticles are
located only substantially within the crystalline grains of the
plasmonic material.
5. The device according to claim 1, wherein the nanoparticles are
located preferentially in the grain boundaries of the plasmonic
material.
6. The device according to claim 1, wherein the nanoparticles are
located in both the crystalline grains and the grain boundaries of
the plasmonic material.
7. The device according to claim 1, wherein there is not greater
than about 30% based on quantification by determining the amount of
the metal element in a metal based nanoparticle and comparing that
to the bulk of the NFT to obtain a percent.
8. The device according to claim 1, wherein the nanoparticles
comprise: oxides of hafnium (Hf), aluminum (Al); nitrides of
zirconium (Zr); or carbides of silicon (Si).
9. The device according to claim 1, wherein the nanoparticles
comprise hafnium (Hf).
10. A device comprising: a near field transducer (NFT) comprising a
crystalline plasmonic material having crystal grains and grain
boundaries; and nanoparticles disposed preferentially on the grain
boundaries, wherein the nanoparticles comprise: oxides of yttrium
(Y), lanthanum (La), barium (Ba), strontium (Sr), erbium (Er),
zirconium (Zr), hafnium (Hf), germanium (Ge), silicon (Si), or
combinations thereof; nitrides of zirconium (Zr), titanium (Ti),
tantalum (Ta), aluminum (Al), boron (B), niobium (Nb), or
combinations thereof; or carbides of silicon (Si), aluminum (Al),
boron (B), zirconium (Zr), tungsten (W), titanium (Ti), niobium
(Nb), or combinations thereof.
11. The device according to claim 10, wherein the plasmonic
material comprises: gold (Au), silver (Ag), ruthenium (Ru), rhodium
(Rh), aluminum (Al), copper (Cu), or combinations thereof.
12. The device according to claim 10, wherein the plasmonic
material comprises: gold (Au), silver (Ag), aluminum (Al), copper
(Cu), or combinations thereof.
13. The device according to claim 10, wherein there is not greater
than about 30% based on quantification by determining the amount of
the metal element in a metal based nanoparticle and comparing that
to the bulk of the NFT to obtain a percent.
14. The device according to claim 10, wherein the nanoparticles
comprise: oxides of yttrium (Y), zirconium (Zr), hafnium (Hf),
aluminum (Al); nitrides of zirconium (Zr), tantalum (Ta); or
carbides of silicon (Si).
15. The device according to claim 10, wherein the nanoparticles
comprise yttrium (Y) or hafnium (Hf).
16. A method comprising: forming a layer comprising a plasmonic
material; forming a layer comprising a metal; and oxidizing,
nitriding or carbiding the metal to form nanoparticles of metal
oxide, metal nitride or metal carbide respectively.
17. The method according to claim 16, wherein the steps of forming
a layer comprising plasmonic material and forming a layer
comprising a metal comprise co-sputtering a single layer comprising
both the plasmonic material and the metal.
18. The method according to claim 16 further comprising repeating
the step of oxidizing, nitriding or carbiding the metal to form
nanoparticles of metal oxide, metal nitride or metal carbide
respectively.
19. The method according to claim 19 further comprising repeating
the steps of forming a layer comprising plasmonic material and
forming a layer comprising a metal.
20. The method according to claim 16, wherein the steps of the
method are carried out while heating a chamber in which the steps
are carried out above room temperature.
Description
PRIORITY
[0001] This application is as continuation of U.S. application Ser.
No. 14/935,753, filed Nov. 9, 2015, which claims priority to U.S.
Provisional Application No. 62/078,848, filed on Nov. 12, 2014, the
disclosure of which is incorporated herein by reference
thereto.
SUMMARY
[0002] Disclosed are devices that include a near field transducer
(NFT) including a crystalline plasmonic material having crystal
grains and grain boundaries; and nanoparticles disposed in the
crystal grains, on the grain boundaries, or some combination
thereof, wherein the nanoparticles are oxides of, lanthanum (La),
barium (Ba), strontium (Sr), erbium (Er), hafnium (Hf), germanium
(Ge), or combinations thereof; nitrides of zirconium (Zr), niobium
(Nb), or combinations thereof; or carbides of silicon (Si),
aluminum (Al), boron (B), zirconium (Zr), tungsten (W), titanium
(Ti), niobium (Nb), or combinations thereof.
[0003] Also disclosed are devices that include a near field
transducer (NFT) including a crystalline plasmonic material having
crystal grains and grain boundaries; and nanoparticles disposed
preferentially on the grain boundaries, or some combination
thereof, wherein the nanoparticles are oxides of yttrium (Y),
lanthanum (La), barium (Ba), strontium (Sr), erbium (Er), zirconium
(Zr), hafnium (Hf), germanium (Ge), silicon (Si), or combinations
thereof; nitrides of zirconium (Zr), titanium (Ti), tantalum (Ta),
aluminum (Al), boron (B), niobium (Nb), or combinations thereof; or
carbides of silicon (Si), aluminum (Al), boron (B), zirconium (Zr),
tungsten (W), titanium (Ti), niobium (Nb), or combinations
thereof.
[0004] Also disclosed are methods that include forming a layer
comprising a plasmonic material; forming a layer comprising a
metal; and oxidizing, nitriding or carbiding the metal to form
nanoparticles of metal oxide, metal nitride or metal carbide
respectively.
[0005] The above summary of the present disclosure is not intended
to describe each disclosed embodiment or every implementation of
the present disclosure. The description that follows more
particularly exemplifies illustrative embodiments. In several
places throughout the application, guidance is provided through
lists of examples, which examples can be used in various
combinations. In each instance, the recited list serves only as a
representative group and should not be interpreted as an exclusive
list.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 is a perspective view of a magnetic disc drive that
can include HAMR devices.
[0007] FIG. 2 is a cross sectional view of a perpendicular HAMR
magnetic recording head and of an associated recording medium.
[0008] FIG. 3 shows (from bottom to top) images of the overall film
and EDX chemical element mapping the oxygen content, the aluminum
content, the yttrium content and the gold content.
[0009] FIGS. 4A and 4B are scanning transmission electron
microscopy (STEM) images of a peg cross section view (FIG. 4A) and
an ABS view (FIG. 4B).
[0010] FIG. 5 shows a scanning electron microscope (SEM) image of a
[10 .ANG. Hf/10 nm Au multilayer].times.2.
[0011] The figures are not necessarily to scale. Like numbers used
in the figures refer to like components. However, it will be
understood that the use of a number to refer to a component in a
given figure is not intended to limit the component in another
figure labeled with the same number.
DETAILED DESCRIPTION
[0012] Heat assisted magnetic recording (referred to through as
HAMR) utilizes radiation, for example from a laser, to heat media
to a temperature above its curie temperature, enabling magnetic
recording. In order to deliver the radiation, e.g., a laser beam,
to a small area (on the order of 20 to 50 nm for example) of the
medium, a NFT is utilized. During a magnetic recording operation,
the NFT absorbs energy from a laser and focuses it to a very small
area; this can cause the temperature of the NFT to increase. The
temperature of the NFT can be elevated up to about 400.degree. C.
or more.
[0013] One method that has been utilized to stabilize the NFT in
the high operating temperatures is to add materials to the main
plasmonic material of the NFT. Metal dopants (for example) and
adhesives have relatively high oxidation tendencies and will move
to an oxidation source, e.g., the NFT surface when it is exposed to
air or O.sub.2. Grain boundaries are a more preferred diffusion
path for materials than is a crystalline lattice. Oxygen can also
quickly diffuse through grain boundaries, and thus metal dopants or
adhesives can be oxidized. Dopants lose their grain stabilization
ability once they have left the plasmonic grains and have
segregated to the NFT surface. Additionally, adhesives will lose
their adhesion benefit once they have been oxidized or segregated
to the NFT surface and oxidized.
[0014] During the manufacture of a HAMR head, various oxidizing
processes are utilized, for example oxygen (O.sub.2) ashing, oxygen
(O.sub.2) etching and high temperature annealing can all be
utilized. A cap layer can be used in situ during NFT peg deposition
and formation to protect the peg from dopant/seed segregation to
the top of the NFT, the sides of the NFT are not as easily
protected. Current head overcoat materials are known to be
permeable to oxygen and can allow oxygen to be in contact with the
NFT during HAMR operation and thus cause those metallic elements to
segregate and be oxidized. A solution is therefore need to make the
plasmonic material of the NFT stable and less sensitive to
oxygen-containing environments.
[0015] Disclosed NFTs include a plasmonic material (e.g., gold
(Au), silver (Ag), rhodium (Rh), ruthenium (Ru), aluminum (Al),
copper (Cu), etc.) where the grain boundaries include
nanoparticles. Nanoparticles disposed in grain boundaries can block
metal and/or oxygen diffusion paths along grain boundaries both
vertically and horizontally. The dopants therefore stay in the
plasmonic material and stabilize the grains. Furthermore, adhesives
are more likely to stay in place to provide their designed adhesion
benefit. The particles themselves (depending on their oxidation
state) at the plasmonic/NPS (NFT to pole space) interface might
also provide adhesion benefits between the plasmonic material and
the oxide (of the NPS). The addition of nanoparticles to the NFT
material also makes the plasmonic material less sensitive to
downstream processes (e.g., O.sub.2 ashing, oxygen (O.sub.2)
etching and high temperature annealing etc.).
[0016] FIG. 1 is a perspective view of disc drive 10 including an
actuation system for positioning slider 12 over track 14 of
magnetic medium 16. The system depicted in FIGS. 1 and 2 can
include disclosed structures and multilayer gas barrier layers. The
particular configuration of disc drive 10 is shown for ease of
description and is not intended to limit the scope of the present
disclosure in any way. Disc drive 10 includes voice coil motor 18
arranged to rotate actuator arm 20 on a spindle around axis 22.
Load beam 24 is connected to actuator arm 20 at head mounting block
26. Suspension 28 is connected to an end of load beam 24 and slider
12 is attached to suspension 28. Magnetic medium 16 rotates around
an axis 30, so that the windage is encountered by slider 12 to keep
it aloft a small distance above the surface of magnetic medium 16.
Each track 14 of magnetic medium 16 is formatted with an array of
data storage cells for storing data. Slider 12 carries a magnetic
device or transducer (not shown in FIG. 1) for reading and/or
writing data on tracks 14 of magnetic medium 16. The magnetic
transducer utilizes additional electromagnetic energy to heat the
surface of medium 16 to facilitate recording by a process termed
heat assisted magnetic recording (HAMR).
[0017] A HAMR transducer includes a magnetic writer for generating
a magnetic field to write to a magnetic medium (e.g. magnetic
medium 16) and an optical device to heat a portion of the magnetic
medium proximate to the write field. FIG. 2 is a cross sectional
view of a portion of a magnetic device, for example a HAMR magnetic
device 40 and a portion of associated magnetic storage medium 42.
HAMR magnetic device 40 includes write pole 44 and return pole 46
coupled by pedestal 48. Coil 50 comprising conductors 52 and 54
encircles the pedestal and is supported by an insulator 56. As
shown, magnetic storage medium 42 is a perpendicular magnetic
medium comprising magnetically hard storage layer 62 and soft
magnetic underlayer 64 but can be other forms of media, such as
patterned media. A current in the coil induces a magnetic field in
the pedestal and the poles. Magnetic flux 58 exits the recording
head at air bearing surface (ABS) 60 and is used to change the
magnetization of portions of magnetically hard layer 62 of storage
medium 42 enclosed within region 58. Near field transducer 66 is
positioned adjacent the write pole 44 proximate air bearing surface
60. Near field transducer 66 is coupled to waveguide 68 that
receives an electromagnetic wave from an energy source such as a
laser. An electric field at the end of near field transducer 66 is
used to heat a portion 69 of magnetically hard layer 62 to lower
the coercivity so that the magnetic field from the write pole can
affect the magnetization of the storage medium. As can be seen in
FIG. 2, a portion of the near field transducer is positioned at the
ABS 60 of the device.
[0018] Devices disclosed herein can also include other structures.
Devices disclosed herein can be incorporated into larger devices.
For example, sliders can include devices as disclosed herein.
Exemplary sliders can include a slider body that has a leading
edge, a trailing edge, and an air bearing surface. The write pole,
read pole, optical near field transducer and contact pad (and
optional heat sink) can then be located on (or in) the slider body.
Such exemplary sliders can be attached to a suspension which can be
incorporated into a disc drive for example. It should also be noted
that disclosed devices can be utilized in systems other than disc
drives such as that depicted in FIGS. 1 and 2.
[0019] Disclosed NFTs include nanoparticles in the plasmonic
material that makes up the NFT. Nanoparticles, as utilized herein
refers to particles (a small object that behaves as a whole unit
with respect to its transport and properties) of material that have
sizes from 1 to 100 nanometers (nm). More specifically,
nanoparticles can include particles that have an average diameter
from 1 to 100 nm. The plasmonic material that can make up the bulk
of the NFT can be a pure material or it can be doped with a dopant
(besides the nanoparticles). The plasmonic materials can include,
for example gold (Au), silver (Ag), ruthenium (Ru), rhodium (Rh),
aluminum (Al) and copper (Cu). Various dopants can be combined with
any of these plasmonic materials. For example, dopants discussed in
US Pat Pub Nos. 2014/0376347 and 2014/0376351; and U.S. Pat. Nos.
8,427,925 and 8,934,198, the disclosures of which are incorporated
herein by reference thereto, as well as other dopants can be
combined with the primary plasmonic material.
[0020] In some embodiments, disclosed NFTs can include
nanoparticles where the majority thereof are within or in the
grains of the primary plasmonic material. Methods of determining
the location of the nanoparticles and quantifying whether they are
only within or in the grains can include transmission electron
microscope (TEM) imaging showing diffraction contrast and/or atomic
Zr contrast between the metal host and the nanoparticles, or a
chemical element mapping technique(s) such as energy dispersive
x-ray (EDX) spectroscopy or electron energy loss spectroscopy
(EELS) for example.
[0021] Plasmonic materials with nanoparticles dispersed
therethrough show good grain stability and much improved hardness.
As such, in some embodiments, the entire NFT or at least a portion
of it, e.g., the peg, includes nanoparticle strengthened plasmonic
material, or stated another way, nanoparticles disposed within or
in the grains. Such NFTs can be made using various methods and
processes. For example, the plasmonic material and the nanoparticle
material can be deposited from a composite target (a target that
contains both materials). A specific illustrative example of such a
target could include a gold target that includes ZrO (or ZrN or
ZrC). Another method includes deposition of the plasmonic material
with a metal from a composite target in a reactive environment
(e.g., an O.sub.2 environment if oxide nanoparticles are being
formed or a N.sub.2 environment if nitride nanoparticles are being
formed). A specific illustrative example of such a target could
include a gold target that includes Zr. Another method includes
co-sputtering of a plasmonic material and a metal from individual
targets in a reactive environment (e.g., an O.sub.2 environment if
oxide nanoparticles are being formed or a N.sub.2 environment if
nitride nanoparticles are being formed). A specific example of such
individual targets could include Au and Zr targets. Another method
includes co-sputtering a plasmonic material and an oxide (or
nitride or carbide) from individual targets. Another method
includes depositing a plasmonic material and flash depositing a
metal and oxidizing (or another treatment to form a nitride, e.g.,
nitriding, or a carbide, e.g., carbiding), and repeating these two
steps. Another method includes depositing a plasmonic material and
flash depositing via atomic layer deposition a metal oxide (or
nitride or carbide), and then repeating these two steps. Another
method can include plasmonic material deposition via sputtering
plus flash deposition of oxides (or nitrides or carbides) by a
different method (for example physical vapor deposition (PVD),
etc.). In some embodiments, plasmonic materials with nanoparticles
dispersed therethrough can be co-sputtered from a composite target
or individual targets.
[0022] In some embodiments, disclosed NFTs can include
nanoparticles preferentially at the grain boundaries as opposed to
within the grains. Nanoparticles described herein as being on the
grain boundaries can also include nanoparticles which are
physically in the grain boundary, where the nanoparticle is in the
grain boundary within the bulk of the plasmonic material, not on a
grain boundary at a surface of the plasmonic material. Such
nanoparticles may provide various benefits: they may stabilize the
plasmonic grains from grain growth and they may block diffusion
paths for seed, dopants or oxygen through the plasmonic grain
boundaries to prevent seed and/or dopant oxidation and segregation,
or any combination thereof. Additionally, nanoparticles at the
grain boundaries may have less of an optical penalty than
nanoparticles in the grains would. Grain boundaries themselves are
already scattering sources in a polycrystalline film. Additionally,
the penalty from the nanoparticles in the grain boundaries might be
smaller than creating new scattering sources by putting the
nanoparticles in the grains. In some embodiments, nanoparticles
being preferentially present at grain boundaries (as opposed to
preferentially present within or in the grains) may be advantageous
because they may be more effective in blocking oxidation paths and
impart less of an optical penalty to the NFT as a whole.
[0023] A NFT that includes nanoparticles preferentially located at
the grain boundaries is one in which at least 50% of the
nanoparticles are located at grain boundaries. In some embodiments,
a NFT that includes nanoparticles preferentially located at the
grain boundaries is one in which at least 75% of the nanoparticles
are located at the grain boundaries. Methods of determining the
location of the nanoparticles and quantifying whether they are only
within the grain boundaries can include transmission electron
microscope (TEM) imaging showing diffraction contrast and/or atomic
Zr contrast between the metal host and the nanoparticles, or a
chemical element mapping technique(s) such as energy dispersive
x-ray (EDX) spectroscopy or electron energy loss spectroscopy
(EELS) for example.
[0024] Such NFTs can be made using various methods and processes.
One such method includes co-sputtering plasmonic material with
another metal at relatively high temperatures (for example at least
200.degree. C.) and periodically oxidizing (or another treatment to
form a nitride or a carbide) and optionally heating the deposited
material and metal. Another method includes forming a plasmonic
material layer and an ultrathin metal layer thereon and then
carrying our periodic oxidation steps (or another treatment to form
a nitride or a carbide) and optional heating steps. Another method
includes sputtering a plasmonic material and a metal from a
composite target at relatively high temperatures (for example, at
least 200.degree. C.) and periodically oxidizing (or another
treatment to form a nitride or a carbide) and optionally heating
the deposited material and metal. A particular illustrative set of
steps that can be carried out to facilitate such a method can
include the following. First, the plasmonic material and a metal
that can easily diffuse to the plasmonic material grain boundaries
can be co-sputtered, or alternatively sputter the plasmonic
material and metal from a composite target. In some embodiments, it
may be more advantageous if thinner layers of plasmonic
material/metal are deposited so that segregation and oxidation may
become more efficient. In some embodiments, the layers have a
thickness less than about 5 nm. Second, the deposition is paused to
allow the metal to segregate to the plasmonic material grain
boundaries. A heat treatment may optionally be utilized at this
point, or throughout the deposition (without necessarily pausing
growth) to facilitate the segregation to the grain boundaries.
Third, an oxidation treatment (e.g., radical shower, radiation,
O.sub.2 plasma, annealing, etc.) can be carried out to oxidize the
metal to form oxide nanoparticles. Alternatively, treatments to
convert the metal to nitrides or carbides could also be carried
out. These three steps can then be repeated until the desired
thickness of plasmonic film/nanoparticles are produced. The
resultant plasmonic material/nanoparticle film has nanoparticles
residing not only in the vertical, but also lateral grain
boundaries. In some embodiments, a plasmonic material film with
nanoparticles on the grain boundaries can be formed using a method
that includes deposition of individual layers (e.g., plasmonic
material and nanoparticle material or material that will be
converted into nanoparticles). In some embodiments, a plasmonic
material film with nanoparticles on the grain boundaries can be
formed using a method that includes deposition of individual layers
(e.g., plasmonic material and nanoparticle material or material
that will be converted into nanoparticles) interspersed with
periodic oxidation with or without heating. In some embodiments, a
plasmonic material film with nanoparticles on the grain boundaries
can be formed using a method that includes deposition of individual
layers (e.g., plasmonic material and nanoparticle material or
material that will be converted into nanoparticles) interspersed
with periodic oxidation with heating (for example, at a temperature
of about 200.degree. C. or higher).
[0025] In some embodiments, disclosed NFTs can include
nanoparticles both within the grains and at the grain boundaries.
In such embodiments, the amount of nanoparticles dispersed
throughout the grains and in the grain boundaries can depend on
various properties of the dopant, e.g., diffusivity, chemical
bonding with the plasmonic material, and segregation tendencies,
for example. Methods of determining the location of the
nanoparticles and quantifying whether they are only within the
grain boundaries can include transmission electron microscope (TEM)
imaging showing diffraction contrast and/or atomic Zr contrast
between the metal host and the nanoparticles, or a chemical element
mapping technique(s) such as energy dispersive x-ray (EDX)
spectroscopy or electron energy loss spectroscopy (EELS) for
example.
[0026] Such NFTs can be made using various methods and processes.
Various methods can be utilized to create nanoparticles at the
grain boundaries. One such method includes forming a plasmonic
layer and an ultrathin (e.g., a layer having a thickness of not
greater than about 5 nm) metal oxide layer (or nitride or carbide)
and repeating these two steps. Another method includes
co-sputtering a plasmonic material and an oxide (or nitride or
carbide) material. Various methods can be utilized to lock the
grains or grain boundaries. One such method includes co-sputtering
plasmonic material--metal in an oxygen (O.sub.2) plasma (or another
treatment to form a nitride or a carbide) at low temperatures to
lock the nanoparticles within the plasmonic material grains due to
their low surface mobility. Another method includes low temperature
deposition of a plasmonic material layer and an ultrathin metal
layer followed by periodic oxidation (or another treatment to form
a nitride or a carbide). In this approach, the ultrathin oxide (or
nitride or carbide) layer could provide advantages by locking the
plasmonic material grain boundaries.
[0027] In some embodiments, only a portion of the NFT can include
the plasmonic material with nanoparticles. For example, the top of
the peg, the bottom of the peg, or both could include plasmonic
material with nanoparticles in order to gain a diffusion blocking
benefit while minimizing the optical penalty by keeping the
nanoparticles away from the optically relevant portion of the peg.
This preferential placement of the plasmonic material with
nanoparticles could be accomplished using nanoparticles only within
the grains of the primary plasmonic material; nanoparticles
preferentially at the grain boundaries as opposed to within the
grains; nanoparticles both within the grains and at the grain
boundaries; or any combination thereof. The use of nanoparticles in
only a portion of the NFT could also apply to non-peg/disc types of
NFTs as well as heatsinks of any types of NFTs.
[0028] In some embodiments, disclosed NFTs can include
nanoparticles preferentially at the interface of the NFT/NPS. The
nanoparticles in such embodiments can be preferentially located on
top of the grain boundaries. Methods of determining the location of
the nanoparticles and quantifying whether they are only within the
grain boundaries can include transmission electron microscope (TEM)
imaging showing diffraction contrast and/or atomic Zr contrast
between the metal host and the nanoparticles, or a chemical element
mapping technique(s) such as energy dispersive x-ray (EDX)
spectroscopy or electron energy loss spectroscopy (EELS) for
example.
[0029] Such NFTs can be made using various methods and processes.
In some embodiments, the nanoparticles are formed after the
dielectric that makes up the NPS is deposited to form the NFT/NPS
interface. One such method can include depositing the plasmonic
material and a metal, for example the plasmonic material and the
metal can be co-sputtered, sputtered from a composite target or a
plasmonic material/metal layer can be formed. Then the NFT can be
formed from the plasmonic material/metal. Next, the dielectric
material making up the NPS can be deposited, covering the NFT. Then
a heat treatment can be carried out to drive metal diffusion
through the plasmonic material grain boundaries and the oxide,
nitride or carbide nanoparticles can then be formed at the NFT/NPS
interface.
[0030] Disclosed NFTs can include various plasmonic materials and
various nanoparticles. The choice of nanoparticle depends at least
in part, on the choice of the plasmonic material. Various
properties can be considered when determining the choice of
nanoparticle material. Properties that may be considered can
include, for example, the enthalpy of segregation (H.sub.seg), the
Gibbs free energy of the formation of the oxide, nitride or carbide
(to indicate the tendency of segregation), the bond energy to
oxygen (to indicate adhesion), the bond energy to oxygen versus the
bond energy to the plasmonic material, the solid solubility in the
plasmonic material, the binary alloy electrical resistivity and the
environmental stability of the oxide phase formed.
[0031] Furthermore, the diffusivity of the material in the
plasmonic material can also be considered. There are three
diffusion kinetic regimes: bulk diffusion--abundant atomic
migration from boundaries into grains; bulk plus grain boundary
diffusion--limited diffusion from boundaries to grains; and grain
boundary diffusion--bulk diffusion is negligible. In some
embodiments, a metal with a diffusivity in the plasmonic material
that is smaller than the plasmonic material self-diffusivity can be
utilized. Such a material can promote grain boundary diffusion
instead of bulk diffusion, can avoid forming an oxide layer on the
surface of the plasmonic material, or both.
[0032] In some embodiments, materials that can be utilized to form
oxide nanoparticles can include, for example, lanthanum (La),
barium (Ba), strontium (Sr), erbium (Er), hafnium (Hf), germanium
(Ge), aluminum (Al), or combinations thereof. In some embodiments,
materials that can be utilized to form oxide nanoparticles can
include, for example, yttrium (Y), zirconium (Zr), silicon (Si), or
combinations thereof. In some embodiments, materials that can be
utilized to form oxide nanoparticles can include, for example
yttrium (Y). In some embodiments, materials that can be utilized to
form oxide nanoparticles can include, for example, yttrium (Y),
zirconium (Zr), hafnium (Hf), aluminum (Al), or combinations
thereof. In some embodiments, materials that can be utilized to
form nitride nanoparticles can include, for example, zirconium
(Zr), niobium (Nb), or combinations thereof. In some embodiments,
materials that can be utilized to form nitride nanoparticles can
include, for example, titanium (Ti), tantalum (Ta), aluminum (Al),
boron (B), or combinations thereof. In some embodiments, materials
that can be utilized to form nitride nanoparticles can include, for
example, zirconium (Zr), tantalum (Ta), or combinations thereof. In
some embodiments, materials that can be utilized to form carbide
nanoparticles can include, for example, silicon (Si), aluminum
(Al), boron (B), zirconium (Zr), tungsten (W), titanium (Ti),
niobium (Nb), or combinations thereof. In some embodiments,
materials that can be utilized to form carbide nanoparticles can
include, for example, silicon (Si).
[0033] In some embodiments, the plasmonic materials can include,
for example gold (Au), silver (Ag), ruthenium (Ru), rhodium (Rh),
aluminum (Al) and copper (Cu) or doped versions thereof. In some
embodiments, the plasmonic materials can include, for example gold
(Au), silver (Ag), aluminum (Al) and copper (Cu) or doped versions
thereof.
[0034] In some embodiments, the amount of nanoparticles in the
plasmonic material of the NFT can be quantified. In some
embodiments, the amount of nanoparticles in the plasmonic material
of the NFT can be quantified by determining the amount of the
cation element (e.g., the metal element in a metal oxide or metal
nitride) in the nanoparticles over the bulk plasmonic material and
comparing that to the bulk to obtain a percent. In some
embodiments, the amount of nanoparticles in the plasmonic material
of the NFT can be quantified by determining a nanoparticle count
and average size measurement by TEM and some sort of chemical
mapping (e.g., EDX or EELS) and then comparing that to the bulk to
obtain a percent. In some embodiments, the amount of nanoparticles
in the plasmonic material of the NFT can be not greater than 30%,
or in some embodiments, not greater than 5%.
[0035] The particular method chosen to oxidize (for example) a
metal to form nanoparticles in a plasmonic material can be chosen
at least in part based on the desired location of the
nanoparticles. One method includes plasmonic material--metal
reactive co-sputtering in O.sub.2. Such methods form oxides in the
grains of the plasmonic material, but not necessarily on the grain
boundaries. Another method includes plasmonic material--metal
co-sputtering combined with periodic oxidation. Such methods may be
more likely to drive segregation and oxidation at the grain
boundaries. Another method includes plasmonic material/metal
multilayer deposition combined with oxidation. Such methods may be
able to deliver the metal to the sidewalls but may offer a higher
chance of causing incomplete segregation and thus possible optical
penalties. Another method includes plasmonic material--oxide
co-sputtering. Such methods may form oxides in the grains of the
plasmonic material. Another method includes forming a compositional
gradient. Such methods may lead to oxides filling the grain
boundaries at the top and bottom of the plasmonic material film to
block diffusion and may afford no dopant at the middle of the
plasmonic material which could cause a lower optical penalty.
[0036] The particular method chosen to oxidize (for example) a
metal to form nanoparticles in a plasmonic material can also be
chosen based in in part on the particular material to be oxidized.
For example, if the element has a higher diffusivity in the
plasmonic material, then co-sputtering combined with oxidation may
be useful or advantageous. If the element has a lower diffusivity
in the plasmonic material, then a multilayer approach may be useful
or advantageous for delivery of the nanoparticles to the grain
boundaries.
[0037] The present disclosure is illustrated by the following
examples. It is to be understood that the particular examples,
assumptions, modeling, and procedures are to be interpreted broadly
in accordance with the scope and spirit of the disclosure as set
forth herein.
EXAMPLES
Example 1
Au/2% Y Via Co-Sputtering
[0038] Gold (Au) and yttrium (Y) were co-sputtered from two
separate metallic targets onto an AlO substrate. Deposition rates
were adjusted to achieve 2 at % Y in the Au. The deposition was
paused at each 5 nm thickness deposited and the wafer was heated to
200.degree. C. and then oxidized in an O.sub.2 radical shower. The
above steps were repeated until a desired thickness was
achieved.
[0039] An array of various sized nanoparticles (from 1 to 3 nm in
size) were realized both in the Au grains and at grain boundaries.
This was confirmed by high angle annular dark field (HAADF)
scanning transmission electron microscopy (STEM) imaging and EDX
chemical element mapping. FIG. 3 shows (from bottom to top) images
of the overall film, the oxygen (O) content, the aluminum (Al)
content, the yttrium (Y) content and the gold (Au) content.
Example 2
Multilayers of 5 nm Gold/2 .ANG. Yttrium Oxide/5 nm Gold/2 .ANG.
Yttrium Oxide
[0040] Multilayers of 5 nm Au and 2 .ANG. YO were prepared by
sputtering from separate Au and YO targets. The YO nanoparticles
formed at each individual Au layer surface. There was a uniform
distribution of YO nanoparticles in the Au which was confirmed by
STEM dark field images on two separate samples. The samples are
seen in FIGS. 4A (peg cross section view) and 4B (ABS view).
Example 3
[Gold/Hafnium-Anneal-Oxidation] Repeat Process
[0041] On a substrate of SiO.sub.2 25 nm AlO was formed via ALD. On
top of that a 5 .ANG. Ta layer was formed followed by a 5 nm Au
layer. Then, a.times..ANG. Hf layer was formed followed by a y nm
Au layer. Then the multilayer structure was subjected to heat
treatment at 200.degree. C. in a N.sub.2 environment for 15
minutes. Next, the multilayer structure was subjected to an O.sub.2
radical shower. The steps of depositing the Hf/Au layer; heat
treatment; and O.sub.2 radical shower were repeated to obtain a
total thickness of 25 to 30 nm. The variables that can be modified
in such a process can include the oxidation conditions, the heat
treatment conditions, the Hf thickness and the Au thickness.
[0042] FIG. 5 shows an image of a [10 .ANG. Hf/10 nm Au
multilayer].times.2.
[0043] All scientific and technical terms used herein have meanings
commonly used in the art unless otherwise specified. The
definitions provided herein are to facilitate understanding of
certain terms used frequently herein and are not meant to limit the
scope of the present disclosure.
[0044] As used in this specification and the appended claims, "top"
and "bottom" (or other terms like "upper" and "lower") are utilized
strictly for relative descriptions and do not imply any overall
orientation of the article in which the described element is
located.
[0045] As used in this specification and the appended claims, the
singular forms "a", "an", and "the" encompass embodiments having
plural referents, unless the content clearly dictates
otherwise.
[0046] As used in this specification and the appended claims, the
term "or" is generally employed in its sense including "and/or"
unless the content clearly dictates otherwise. The term "and/or"
means one or all of the listed elements or a combination of any two
or more of the listed elements.
[0047] As used herein, "have", "having", "include", "including",
"comprise", "comprising" or the like are used in their open ended
sense, and generally mean "including, but not limited to". It will
be understood that "consisting essentially of", "consisting of",
and the like are subsumed in "comprising" and the like. For
example, a conductive trace that "comprises" silver may be a
conductive trace that "consists of" silver or that "consists
essentially of" silver.
[0048] As used herein, "consisting essentially of," as it relates
to a composition, apparatus, system, method or the like, means that
the components of the composition, apparatus, system, method or the
like are limited to the enumerated components and any other
components that do not materially affect the basic and novel
characteristic(s) of the composition, apparatus, system, method or
the like.
[0049] The words "preferred" and "preferably" refer to embodiments
that may afford certain benefits, under certain circumstances.
However, other embodiments may also be preferred, under the same or
other circumstances. Furthermore, the recitation of one or more
preferred embodiments does not imply that other embodiments are not
useful, and is not intended to exclude other embodiments from the
scope of the disclosure, including the claims.
[0050] Also herein, the recitations of numerical ranges by
endpoints include all numbers subsumed within that range (e.g., 1
to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc. or 10 or less
includes 10, 9.4, 7.6, 5, 4.3, 2.9, 1.62, 0.3, etc.). Where a range
of values is "up to" a particular value, that value is included
within the range.
[0051] Use of "first," "second," etc. in the description above and
the claims that follow is not intended to necessarily indicate that
the enumerated number of objects are present. For example, a
"second" substrate is merely intended to differentiate from another
infusion device (such as a "first" substrate). Use of "first,"
"second," etc. in the description above and the claims that follow
is also not necessarily intended to indicate that one comes earlier
in time than the other.
[0052] Thus, embodiments of devices including a near field
transducer (NFT) with nanoparticles are disclosed. The
implementations described above and other implementations are
within the scope of the following claims. One skilled in the art
will appreciate that the present disclosure can be practiced with
embodiments other than those disclosed. The disclosed embodiments
are presented for purposes of illustration and not limitation.
* * * * *