U.S. patent application number 15/890101 was filed with the patent office on 2019-05-23 for method and system for providing a boron-free magnetic layer in perpendicular magnetic junctions.
The applicant listed for this patent is Samsung Electronics Co., LTD.. Invention is credited to Ikhtiar, Mohamad Towfik Krounbi, Xueti Tang.
Application Number | 20190157547 15/890101 |
Document ID | / |
Family ID | 66334050 |
Filed Date | 2019-05-23 |
United States Patent
Application |
20190157547 |
Kind Code |
A1 |
Ikhtiar; ; et al. |
May 23, 2019 |
METHOD AND SYSTEM FOR PROVIDING A BORON-FREE MAGNETIC LAYER IN
PERPENDICULAR MAGNETIC JUNCTIONS
Abstract
A magnetic junction and method for providing the magnetic
junction are described. The method includes providing a pinned
layer, a nonmagnetic spacer layer and a free layer switchable
between stable magnetic states. The nonmagnetic spacer layer is
between the pinned and free layers. Providing the pinned layer
and/or providing the free layer includes cooling a portion of the
magnetic junction, depositing a wetting layer while the portion of
the magnetic junction is cooled, oxidizing/nitriding the wetting
layer and depositing a boron-free magnetic layer on the
oxide/nitride wetting layer. The portion of the magnetic junction
is cooled to within a temperature range including temperature(s)
not greater than 250 K. The wetting layer has a thickness of at
least 0.25 and not more than three monolayers. The wetting layer
includes at least one magnetic material. The boron-free magnetic
layer has a perpendicular magnetic anisotropy energy greater than
an out-of-plane demagnetization energy.
Inventors: |
Ikhtiar;; (Milpitas, CA)
; Tang; Xueti; (Fremont, CA) ; Krounbi; Mohamad
Towfik; (San Jose, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Samsung Electronics Co., LTD. |
Gyeonggi-do |
|
KR |
|
|
Family ID: |
66334050 |
Appl. No.: |
15/890101 |
Filed: |
February 6, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62588579 |
Nov 20, 2017 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01F 10/3286 20130101;
H01L 27/222 20130101; H01F 10/1936 20130101; G11C 11/161 20130101;
H01F 10/10 20130101; H01L 43/08 20130101; H01F 10/3254 20130101;
H01L 43/12 20130101; H01F 41/14 20130101; H01F 41/303 20130101 |
International
Class: |
H01L 43/12 20060101
H01L043/12; H01L 43/08 20060101 H01L043/08; G11C 11/16 20060101
G11C011/16; H01F 10/10 20060101 H01F010/10; H01F 41/14 20060101
H01F041/14; H01L 27/22 20060101 H01L027/22 |
Claims
1. A method for providing magnetic junction residing on a substrate
and usable in a magnetic device, the method comprising: providing a
pinned layer, the pinned layer being magnetic; providing a
nonmagnetic spacer layer; and providing a free layer, the
nonmagnetic spacer layer being between the pinned layer and the
free layer, the free layer being magnetic and switchable between a
plurality of stable magnetic states, wherein at least one of the
step of providing the pinned layer and the step of providing the
free layer further include cooling a portion of the magnetic
junction to within a temperature range including at least one
temperature not greater than 250 K; depositing a wetting layer
while the portion of the magnetic junction is cooled, the wetting
layer having a thickness of not more than three monolayers and at
least 0.25 monolayer, the wetting layer including at least one
magnetic material; at least one of oxidizing and nitriding the
wetting layer to provide a treated wetting layer, the treated
wetting layer being an oxide wetting layer for an oxidizing process
and a nitride wetting layer for a nitriding process; and depositing
a boron-free magnetic layer on the treated wetting layer while at
least the oxide wetting layer for the oxidizing process and the
nitride wetting layer for the nitriding process is within the
temperature range, the boron-free magnetic layer having a
perpendicular magnetic anisotropy energy greater than an
out-of-plane demagnetization energy.
2. The method of claim 1 wherein the temperature range is at least
50K and not greater than 150K.
3. The method of claim 2 wherein the temperature range is at least
70K and not greater than 100K.
4. The method of claim 1 wherein the wetting layer has a thickness
of at least 0.5 monolayer and not more than two monolayers.
5. The method of claim 2 wherein the wetting layer has a thickness
of at least 0.75 monolayer and not more than 1.25 monolayers.
6. The method of claim 1 wherein the step of providing the at least
one of the free layer and the pinned layer further includes:
annealing the boron-free magnetic layer at a temperature above 300
K.
7. The method of claim 1 wherein the oxidizing step further
includes: naturally oxidizing the wetting layer.
8. The method of claim 1 wherein the wetting layer includes at
least one of elemental Fe, elemental Co, elemental Ni, elemental
Mn, an Fe-containing alloy, a Co-containing alloy, a Ni-containing
alloy and a Mn containing alloy.
9. The method of claim 1 wherein the boron-free magnetic layer
includes at least one of elemental Fe, elemental Co, elemental Ni,
elemental Mn, an Fe-containing alloy, a Co-containing alloy, a
Ni-containing alloy, a Mn containing alloy and a Heusler alloy.
10. The method of claim 1 wherein the step of providing the wetting
layer further includes: providing the wetting layer on an oxide
layer.
11. The method of claim 10 wherein the nonmagnetic spacer layer
includes the oxide layer.
12. The method of claim 1 wherein the step of providing the at
least one of the free layer and the pinned layer further includes:
providing an oxide capping layer on the boron-free magnetic
layer.
13. The method of claim 1 further comprising: providing an
additional nonmagnetic spacer layer; and providing an additional
pinned layer, the additional nonmagnetic spacer layer being between
the additional pinned layer and the free layer.
14. The method of claim 1 wherein the at least one of the free
layer and the pinned layer includes a polarization enhancement
layer, and wherein the polarization enhancement layer includes the
boron-free magnetic layer.
15. The method of claim 1 wherein the free layer is a
multilayer.
16. The method of claim 1 wherein pinned layer is a multilayer.
17. The method of claim 1 wherein the free layer is switchable
between the plurality of stable magnetic states using at least one
of spin transfer torque and spin-orbit coupling torque.
18. A method for providing magnetic junction residing on a
substrate and usable in a magnetic device, the method comprising:
providing a pinned layer, the pinned layer being magnetic;
providing a nonmagnetic spacer layer; and providing a free layer,
the nonmagnetic spacer layer being between the pinned layer and the
free layer, the free layer being magnetic and switchable between a
plurality of stable magnetic states using at least one of spin
transfer torque and spin-orbit coupling torque, wherein at least
one of the step of providing the pinned layer and the step of
providing the free layer further include depositing a wetting layer
while the portion of the magnetic junction is cooled, the wetting
layer having a thickness of not more than three monolayers and at
least 0.25 monolayer, the wetting layer including at least one
magnetic material; at least one of oxidizing and nitriding the
wetting layer to provide a treated wetting layer, the treated
wetting layer being an oxide wetting layer for an oxidizing process
and a nitride wetting layer for a nitriding process; cooling a
portion of the magnetic junction including the treated wetting
layer to within a temperature range including at least one
temperature not greater than 250 K; and depositing a boron-free
magnetic layer on the treated wetting layer while the portion of
the magnetic junction is within the temperature range, the
boron-free magnetic layer having a perpendicular magnetic
anisotropy energy greater than an out-of-plane demagnetization
energy.
19. A memory magnetic junction residing on a substrate and
comprising: a plurality of magnetic storage cells, each of the
plurality of magnetic storage cells including at least one magnetic
junction, the at least one magnetic junction including a free
layer, a nonmagnetic spacer layer and a pinned layer, the
nonmagnetic spacer layer residing between the pinned layer and the
free layer, the free layer being switchable between a plurality of
stable magnetic states when a write current is passed through the
magnetic junction, at least one of the free layer and the pinned
layer including a boron-free magnetic layer, the boron-free
magnetic layer having a perpendicular magnetic anisotropy energy
greater than an out-of-plane demagnetization energy.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of provisional Patent
Application Ser. No. 62/588,579, filed Nov. 20, 2017, entitled
BORON-FREE FREE LAYER FOR PERPENDICULAR MAGNETIC JUNCTIONS,
assigned to the assignee of the present application, and
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] Magnetic memories, particularly magnetic random access
memories (MRAMs), have drawn increasing interest due to their
potential for high read/write speed, excellent endurance,
non-volatility and low power consumption during operation. An MRAM
can store information utilizing magnetic materials as an
information recording medium. One type of MRAM is a spin transfer
torque random access memory (STT-MRAM). STT-MRAM utilizes magnetic
junctions written at least in part by a current driven through the
magnetic junction. A spin polarized current driven through the
magnetic junction exerts a spin torque on the magnetic moments in
the magnetic junction. As a result, layer(s) having magnetic
moments that are responsive to the spin torque may be switched to a
desired state.
[0003] For example, a conventional magnetic tunneling junction
(MTJ) may be used in a conventional STT-MRAM. The conventional MTJ
typically resides on a substrate. The conventional MTJ, uses
conventional seed layer(s), may include capping layers and may
include a conventional antiferromagnetic (AFM) layer. The
conventional MTJ includes a conventional pinned layer, a
conventional free layer and a conventional tunneling barrier layer
between the conventional pinned and free layers. A bottom contact
below the conventional MTJ and a top contact on the conventional
MTJ may be used to drive current through the conventional MTJ in a
current-perpendicular-to-plane (CPP) direction. The reference layer
and the free layer are magnetic. The magnetization of the reference
layer is fixed, or pinned, in a particular direction. The free
layer has a changeable magnetization. The free layer and reference
layer may be a single layer or include multiple layers.
[0004] To switch the magnetization of the free layer, a current is
driven in the CPP direction. When a sufficient current is driven
from the top contact to the bottom contact, the magnetization of
the free layer may switch to be parallel to the magnetization of a
bottom reference layer. When a sufficient current is driven from
the bottom contact to the top contact, the magnetization of the
free layer may switch to be antiparallel to that of the bottom
reference layer. The differences in magnetic configurations
correspond to different magnetoresistances and thus different
logical states (e.g. a logical "0" and a logical "1") of the
conventional MTJ.
[0005] Because of their potential for use in a variety of
applications, research in magnetic memories is ongoing. For
example, a low switching current, sufficient thermal stability and
high perpendicular magnetic anisotropy may be desired for improved
write efficiency and data retention. These properties are desired
to be present in the magnetic junctions in the final device.
Accordingly, what is needed is a method and system that may improve
the performance of spin transfer torque based memories and the
electronic devices in which such memories are used. The method and
system described herein address such a need.
BRIEF SUMMARY OF THE INVENTION
[0006] A magnetic junction and method for providing the magnetic
junction are described. The method includes providing a pinned
layer, providing a nonmagnetic spacer layer and providing a free
layer switchable between stable magnetic states. The nonmagnetic
spacer layer is between the pinned and free layers. Providing the
pinned layer and/or providing the free layer includes cooling a
portion of the magnetic junction, depositing a wetting layer while
the portion of the magnetic junction is cooled, oxidizing or
nitriding the wetting layer to provide an oxide or nitride wetting
layer and depositing a boron-free magnetic layer on the
oxide/nitride wetting layer. The portion of the magnetic junction
is cooled to within a temperature range including temperature(s)
not greater than 250 K. The wetting layer has a thickness of at
least 0.25 monolayer and not more than three monolayers. The
wetting layer includes at least one magnetic material. The
boron-free magnetic layer has a perpendicular magnetic anisotropy
energy greater than an out-of-plane demagnetization energy.
[0007] Using the method and system, the free layer and/or pinned
layer may include or consist of a boron-free layer. Thus, the
perpendicular magnetic anisotropy, stability and switching
performance of the magnetic junction may be improved.
BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS
[0008] FIG. 1 is a flow chart depicting an exemplary embodiment of
a method for providing a boron-free magnetic layer for a magnetic
junction usable in magnetic devices such as a magnetic memory
programmable using spin transfer torque.
[0009] FIGS. 2-5 depict an exemplary embodiment of a layer for a
magnetic junction usable in magnetic devices such as a magnetic
memory programmable using spin transfer torque during
fabrication.
[0010] FIG. 6 is a flow chart depicting another exemplary
embodiment of a method for providing a boron-free magnetic layer
for a magnetic junction usable in magnetic devices such as a
magnetic memory programmable using spin transfer torque.
[0011] FIG. 7 is a flow chart depicting an exemplary embodiment of
a method for providing a magnetic junction that includes boron-free
magnetic layer(s) and that is usable in magnetic devices such as a
magnetic memory programmable using spin transfer torque.
[0012] FIG. 8 depicts an exemplary embodiment of a magnetic
junction having boron-free magnetic layer(s) and usable in magnetic
devices such as a magnetic memory programmable using spin transfer
torque.
[0013] FIG. 9 depicts another exemplary embodiment of a magnetic
junction having boron-free magnetic layer(s) and usable in magnetic
devices such as a magnetic memory programmable using spin transfer
torque.
[0014] FIG. 10 depicts another exemplary embodiment of a magnetic
junction having boron-free magnetic layer(s) and usable in magnetic
devices such as a magnetic memory programmable using spin transfer
torque.
[0015] FIG. 11 depicts another exemplary embodiment of a magnetic
junction having boron-free magnetic layer(s) and usable in magnetic
devices such as a magnetic memory programmable using spin transfer
torque.
[0016] FIG. 12 depicts an exemplary embodiment of a memory
utilizing magnetic junctions that have boron-free magnetic layer(s)
in the memory element(s) of the storage cell(s).
DETAILED DESCRIPTION OF THE INVENTION
[0017] The exemplary embodiments relate to magnetic junctions
usable in magnetic devices, such as magnetic memories, and the
devices using such magnetic junctions. The magnetic memories may
include spin transfer torque magnetic random access memories
(STT-MRAMs), spin-orbit coupling torque (SOT) memories, and may be
used in electronic devices employing nonvolatile memory. Other
devices including magnetic junctions, particularly STT or SOT
programmable magnetic junctions include but are not limited to
logic, neuromorphic computing cells and other devices. Electronic
devices include but are not limited to cellular phones, smart
phones, tables, laptops and other portable and non-portable
computing devices. The following description is presented to enable
one of ordinary skill in the art to make and use the invention and
is provided in the context of a patent application and its
requirements. Various modifications to the exemplary embodiments
and the generic principles and features described herein will be
readily apparent. The exemplary embodiments are mainly described in
terms of particular methods and systems provided in particular
implementations. However, the methods and systems will operate
effectively in other implementations. Phrases such as "exemplary
embodiment", "one embodiment" and "another embodiment" may refer to
the same or different embodiments as well as to multiple
embodiments. The embodiments will be described with respect to
systems and/or devices having certain components. However, the
systems and/or devices may include more or fewer components than
those shown, and variations in the arrangement and type of the
components may be made without departing from the scope of the
invention. The exemplary embodiments will also be described in the
context of particular methods having certain steps. However, the
method and system operate effectively for other methods having
different and/or additional steps and steps in different orders
that are not inconsistent with the exemplary embodiments. Thus, the
present invention is not intended to be limited to the embodiments
shown, but is to be accorded the widest scope consistent with the
principles and features described herein.
[0018] A magnetic junction and method for providing the magnetic
junction are described. The method includes providing a pinned
layer, providing a nonmagnetic spacer layer and providing a free
layer switchable between stable magnetic states. The nonmagnetic
spacer layer is between the pinned and free layers. Providing the
pinned layer and/or providing the free layer includes cooling a
portion of the magnetic junction, depositing a wetting layer while
the portion of the magnetic junction is cooled, oxidizing and/or
nitriding the wetting layer to provide an oxide/nitride wetting
layer and depositing a boron-free magnetic layer on the
oxide/nitride wetting layer. The portion of the magnetic junction
is cooled to within a temperature range including temperature(s)
not greater than 250 K. The wetting layer has a thickness of at
least 0.25 monolayer and not more than three monolayers. The
wetting layer includes at least one magnetic material. The
boron-free magnetic layer has a perpendicular magnetic anisotropy
energy greater than an out-of-plane demagnetization energy.
[0019] The exemplary embodiments are described in the context of
particular methods, magnetic junctions and magnetic memories having
certain components. One of ordinary skill in the art will readily
recognize that the present invention is consistent with the use of
magnetic junctions and magnetic memories having other and/or
additional components and/or other features not inconsistent with
the present invention. The method and system are also described in
the context of current understanding of the spin transfer
phenomenon, of magnetic anisotropy, and other physical phenomenon.
Consequently, one of ordinary skill in the art will readily
recognize that theoretical explanations of the behavior of the
method and system are made based upon this current understanding of
spin transfer, magnetic anisotropy and other physical phenomena.
However, the method and system described herein are not dependent
upon a particular physical explanation. One of ordinary skill in
the art will also readily recognize that the method and system are
described in the context of a structure having a particular
relationship to the substrate. One of ordinary skill in the art
will readily recognize that the method and system are consistent
with other structures. In addition, the method and system are
described in the context of certain layers being synthetic and/or
simple. However, one of ordinary skill in the art will readily
recognize that the layers could have another structure.
Furthermore, the method and system are described in the context of
magnetic junctions and/or substructures having particular layers.
One of ordinary skill in the art will readily recognize that
magnetic junctions and/or substructures having additional and/or
different layers not inconsistent with the method and system could
also be used. Moreover, certain components are described as being
magnetic, ferromagnetic, and ferrimagnetic. As used herein, the
term magnetic could include ferromagnetic, ferrimagnetic or like
structures. Thus, as used herein, the term "magnetic" or
"ferromagnetic" includes, but is not limited to ferromagnets and
ferrimagnets. As used herein, "in-plane" is substantially within or
parallel to the plane of one or more of the layers of a magnetic
junction. Conversely, "perpendicular" and "perpendicular-to-plane"
corresponds to a direction that is substantially perpendicular to
one or more of the layers of the magnetic junction. The method and
system are also described in the context of certain alloys. Unless
otherwise specified, if specific concentrations of the alloy are
not mentioned, any stoichiometry not inconsistent with the method
and system may be used.
[0020] The use of the terms "a" and "an" and "the" and similar
referents in the context of describing the invention (especially in
the context of the following claims) are to be construed to cover
both the singular and the plural, unless otherwise indicated herein
or clearly contradicted by context. The terms "comprising,"
"having," "including," and "containing" are to be construed as
open-ended terms (i.e., meaning "including, but not limited to,")
unless otherwise noted.
[0021] Unless defined otherwise, all technical and scientific terms
used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which this invention belongs. It is
noted that the use of any and all examples, or exemplary terms
provided herein is intended merely to better illuminate the
invention and is not a limitation on the scope of the invention
unless otherwise specified. Further, unless defined otherwise, all
terms defined in generally used dictionaries may not be overly
interpreted.
[0022] Although described in the context of a boron-free free
magnetic layer, in alternate embodiment, the method and system may
be used to fabricate magnetic junctions that are free of other
and/or all glass-forming components. For example, the layer may not
include B, C and other glass-forming material(s) used in providing
a layer that is amorphous-as deposited.
[0023] FIG. 1 is a flow chart depicting an exemplary embodiment of
a method for providing a boron-free magnetic layer for a magnetic
junction usable in magnetic devices such as a magnetic memory
programmable using spin transfer torque (STT) and/or spin-orbit
coupling torque (SOT). The magnetic layers of the magnetic junction
may have a high perpendicular magnetic anisotropy (PMA). Stated
differently, the perpendicular magnetic anisotropy energy may
exceed the out-of-plane demagnetization energy. Such a
configuration allows for the magnetic moment of a high PMA layer to
be stable perpendicular to plane. For simplicity, some steps may be
omitted, performed in another order, include substeps and/or
combined. Further, the method 100 may start after other steps in
forming a magnetic junction have been performed. FIGS. 2-5 depict
an exemplary embodiment of a portion 200 for a magnetic junction
that may be fabricated using the method 100. FIGS. 2-5 are not to
scale. Referring to FIGS. 1-5, the method 100 is described in the
context of the layers 200 for the magnetic junction. However,
analogous layer for other magnetic junctions may be formed.
Further, multiple layers for multiple magnetic junctions may be
simultaneously fabricated. The layer(s) described herein may be
used in forming all or part of a free layer, a pinned layer, or
other magnetic layer in a magnetic junction.
[0024] A portion of the magnetic junction that has already been
fabricated is cryo-cooled to within a temperature range including
temperatures not greater than 250 K, via step 102. In some
embodiments, the temperature range includes temperature(s) of at
least 50K and not greater than 150K. In some such embodiments, the
temperature range is from at least 70K through not greater than
100K. FIG. 2 depicts a portion of the magnetic layers 200 being
formed. Thus, the underlayer 202 is cooled to a wafer temperature
described above. The underlayer 202 may be an oxide layer and may
function as a seed layer for subsequent layers. In some
embodiments, the underlayer 202 may be a tunneling barrier layer
that is part of a single/bottom pinned or dual magnetic junction.
Thus, the underlayer 202 may be a crystalline MgO layer, an
MgAl.sub.2O.sub.4 layer, an MgTiOx (where Ox denotes an oxide of
varying stoichiometry), or other insulating layer that may serve in
whole or in part as the tunneling barrier layer for a magnetic
tunneling junction. Alternatively, the underlayer 202 may be an
oxide seed layer. For example, if a single top-pinned magnetic
junction is formed, then the underlayer 202 may be a seed layer
that can also be used to enhance the PMA of the free layer. If a
single bottom-pinned magnetic junction or a dual magnetic junction
is formed, then the underlayer 202 may be a seed layer that may
increase the PMA of the pinned layer.
[0025] While the underlayer 202 is cooled, a thin wetting layer is
deposited, via step 104. Step 104 may be carried out via
sputtering, physical vapor deposition (PVD) or other appropriate
process. The underlayer 202 is cooled for step 104 to encourage
atoms of the wetting layer provided in step 104 to spread uniformly
across the underlayer 202. Consequently, the formation of islands
is discouraged. However, as discussed below, less than a monolayer
may be deposited in step 104. Thus, the wetting layer provided in
step 104 may not be continuous and/or may have voids therein.
However, the wetting layer provided in step 104 is smoother/has a
lower surface roughness than if deposited at higher
temperatures.
[0026] FIG. 3 depicts the layers 200 after step 104. Thus, a
wetting layer 204 has been deposited. Although depicted as a
continuous layer, as discussed above, the wetting layer 204 need
not be. The wetting layer 204 includes material(s) that may be used
as a precursor to a subsequent magnetic layer. The wetting layer
204 may include or consist of 3d transition metal(s) and/or their
alloys. For example, might consist at least one of elemental Fe,
elemental Co, elemental Ni, elemental Mn, an Fe-containing alloy
such as CoFe, a Co-containing alloy such as CoFe, a Ni-containing
alloy and a Mn containing alloy. With the exception of B and
optionally other materials, such as nontransition metals, might be
included as part of the alloy used in the wetting layer. However,
step 104 may omit the deposition of any foreign atoms in the
wetting layer 204. Foreign atoms are any atoms not included in the
subsequent boron-free layer, described below. In addition, in some
embodiments, the material(s) used for the wetting layer 204 are
also desired to be magnetic. The wetting layer 204 is also thin. In
some embodiments, the wetting layer thickness is at least 0.25
monolayer and not more than three monolayers. In some cases, the
thickness may be at least 0.5 monolayers and not more than two
monolayers. In some such embodiments the wetting layer 204 has a
thickness of at least 0.75 monolayer and not more than 1.25
monolayers.
[0027] The wetting layer 204 is treated, via step 106. The wetting
layer is oxidized or nitrided in this step. Step 106 may include
naturally oxidizing the wetting layer 204. In other embodiments,
other oxidation methods such as reactive oxidation may be employed.
Similarly, step 106 may include naturally or reactively nitriding
the wetting layer. The oxidation/nitridation step is desired to
continue until a target RA (resistance area product) is achieved.
In some embodiments, the RA target is nominally ten. However, other
Ras or other measures of the oxidation may be used to determine
when to terminate oxidation. In some embodiments, step 106 may be
continued until the wetting layer 204 is completely
oxidized/nitrided. In addition, because step 106 is performed
shortly after step 104, the wafer/portion of the magnetic junction
already provided may still be cooled. For example, the portion of
the magnetic junction already formed may be in the temperature
range described above for steps 102 and 104. Thus, a treated
wetting layer is provided. The treated wetting layer may be an
oxide wetting layer or a nitride wetting layer.
[0028] FIG. 4 depicts the layers 200 after step 106 is performed.
Thus, the oxide/nitride wetting layer 204' has been formed.
Although all of the wetting layer 204 appears to have been
converted to an oxide/nitride in FIG. 4, in other embodiments the
oxidation/nitridation may not be complete. For example, the
oxide/nitride wetting layer 204' may include or consist of Fe-Ox
and/or CoFe-Ox where Ox denotes an oxide.
[0029] A boron-free magnetic layer is deposited on the
oxide/nitride wetting layer 204', via step 108. The material(s)
deposited for the boron-free magnetic layer may include the
material(s) deposited for the oxide/nitride wetting layer 204' in
step 104. Step 108 may include depositing 3d transition metals,
their alloys and/or Heusler alloys such as Co.sub.2Fe,
Co.sub.2MnSi, Co.sub.2FeMnSi, Co.sub.2FeSi, MnGa, and MnGe. Thus,
binary, ternary and other alloys not including boron may be
deposited in step 108. Stated differently, other and/or additional
nonmagnetic and/or magnetic materials excluding boron may be
provided in step 108 for the boron-free magnetic layer. For
example, CoX, FeX, NiX, CoFeX and/or CoFeNiX, where X is not B, may
be used. Similarly, elements such as Fe, Co, Ni and Mn might be
deposited. Thus, step 108 may include depositing at least one of
elemental Fe, elemental Co, elemental Ni, elemental Mn, an
Fe-containing alloy such as CoFe, a Co-containing alloy such as
CoFe, a Ni-containing alloy, a Mn containing alloy and a Heusler
alloy.
[0030] In at least some embodiments, the underlying layers, which
were cryo-cooled in step 102, may still be cool during step 108.
This is because the time between the cooling step 102 and the
boron-free magnetic layer deposition step 108 may be quite short in
comparison to the time taken for the wafer's temperature to
increase to room temperature naturally. Thus, the temperature of
the underlying layers may be well under three hundred Kelvin in
step 108, for example not more than two hundred fifty Kelvin. For
example, in some embodiments, the temperature of the wafer may be
not more than two hundred Kelvin at the start of the deposition of
the boron-free magnetic layer. In some such embodiments, the
temperature of the wafer may not exceed one hundred Kelvin at the
start of the deposition. In an alternate embodiment, the deposition
in step 108 may include a second cooling step. In such embodiments,
the underlayer(s)/wafer are cooled prior to the deposition of the
wetting layer in step 102 and again as part of/before deposition of
the boron-free magnetic layer in step 108. The cooling as part of
step 108 may be to the same temperature ranges as in step 102.
Alternatively, the device may be cooled to temperatures that are
higher but still less than three hundred Kelvin. For example, a
cryo-cooling performed in step 108 may be to temperatures not
exceeding two hundred fifty Kelvin. However, such a second cooling
step may be unnecessary as long as the wafer remains cool in step
108 due to the cooling in step 102.
[0031] FIG. 5 depicts the layer 200 after step 108 has been
completed. Thus, the boron-free magnetic layer 206 has been formed.
The boron-free magnetic layer 206 may include the materials
described above and may be polycrystalline as deposited. In
addition, the boron-free magnetic layer 206 may have a high PMA.
The perpendicular magnetic anisotropy energy of the layer 206 may
exceed the out-of-plane demagnetization energy. Thus, the magnetic
moment (not shown) of the boron-free magnetic layer 206 may be
stable perpendicular-to-plane.
[0032] Fabrication of the magnetic junction may then be completed,
via step 110. Step 110 may include annealing the layers 200 at
temperature(s) above room temperature (300K) to complete
crystallization of the boron-free magnetic layer 206. For example,
a rapid thermal anneal may be employed. A plasma etch may be used
in addition to or in lieu of the anneal to improve crystallinity.
An oxide layer may also be deposited on the boron-free magnetic
layer 206. The oxide layer may be a tunneling barrier layer or a
capping layer. Alternatively, other layers might be provided on the
boron-free magnetic layer 206. Further, as the boron-free magnetic
layer 206 is part of the magnetic junction stack, the boron-free
magnetic layer 206 as well as other layers in the device may be
masked, etched to define the magnetic junction and/or undergo other
processing.
[0033] Using the method 100, a boron-free magnetic layer 206 having
a high PMA may be fabricated. When used in the free layer, the
boron-free magnetic layer 206 may have improved stability. The
magnetoresistance of such a magnetic junction may also be improved.
Further, if the free layer consists of the boron-free magnetic
layer 206, the free layer is compositionally uniform. As such,
switching performance of the magnetic junction may be improved. If
used in the pinned layer, the boron-free magnetic layer 206 may
also improve the PMA of such a layer. Thus, performance a magnetic
junction formed with the layer 206 fabricated using the method 100
may be improved.
[0034] FIG. 6 is a flow chart depicting an exemplary embodiment of
a method 100A for providing a boron-free magnetic layer for a
magnetic junction usable in magnetic devices such as a magnetic
memory programmable using STT and/or SOT. The magnetic layers of
the magnetic junction may have a high PMA. Stated differently, the
perpendicular magnetic anisotropy energy may exceed the
out-of-plane demagnetization energy. Such a configuration allows
for the magnetic moment of a high PMA layer to be stable
perpendicular to plane. For simplicity, some steps may be omitted,
performed in another order, include substeps and/or combined.
Further, the method 100A may start after other steps in forming a
magnetic junction have been performed. The method 100A is analogous
to the method 100. Consequently, similar steps have analogous
labels. The layer(s) described herein may be used in forming all or
part of a free layer, a pinned layer, or other magnetic layer in a
magnetic junction.
[0035] A thin wetting layer is deposited, via step 102A. Step 102A
may be carried out via sputtering, PVD or other appropriate
process. Step 102A is analogous to step 104 of the method 100.
However, the device is not cryo-cooled prior to step 102A. The
wetting layer is deposited on an underlayer that may be an oxide
layer and may function as a seed layer for subsequent layers. In
some embodiments, the underlayer may be a tunneling barrier layer
that is part of a single/bottom pinned or dual magnetic junction.
Thus, the underlayer may be a crystalline MgO layer, an
MgAl.sub.2O.sub.4 layer, an MgTiOx, or other insulating layer that
may serve in whole or in part as the tunneling barrier layer for a
magnetic tunneling junction. Alternatively, the underlayer may be
an oxide seed layer. For example, if a single top-pinned magnetic
junction is formed, then the underlayer may be a seed layer that
can also be used to enhance the PMA of the free layer. If a single
bottom-pinned magnetic junction or a dual magnetic junction is
formed, then the underlayer may be a seed layer that may increase
the PMA of the pinned layer.
[0036] The wetting layer that is deposited in step 102A may be a
continuous layer or may have pinholes/apertures therein. The
wetting layer deposited is analogous to the wetting layer 204
described above and may include analogous materials. The wetting
layer includes material(s) that may be used as a precursor to a
subsequent magnetic layer. The wetting layer may include or consist
of 3d transition metal(s) and/or their alloys. For example, might
consist at least one of elemental Fe, elemental Co, elemental Ni,
elemental Mn, an Fe-containing alloy such as CoFe, a Co-containing
alloy such as CoFe, a Ni-containing alloy and a Mn containing
alloy. With the exception of B and optionally other materials, such
as nontransition metals, might be included as part of the alloy
used in the wetting layer. However, step 102A may omit the
deposition of any foreign atoms in the wetting layer. Foreign atoms
are any atoms not included in the subsequent boron-free layer,
described below. In addition, in some embodiments, the material(s)
used for the wetting layer are also desired to be magnetic. The
wetting layer is also thin. In some embodiments, the wetting layer
thickness is at least 0.25 monolayer and not more than three
monolayers. In some cases, the thickness may be at least 0.5
monolayers and not more than two monolayers. In some such
embodiments the wetting layer 204 has a thickness of at least 0.75
monolayer and not more than 1.25 monolayers.
[0037] The wetting layer is oxidized and/or nitrided, via step
104A. Step 104A is analogous to step 106 of the method 100. Step
104A may include naturally oxidizing the wetting layer. In other
embodiments, other oxidation methods such as reactive oxidation may
be employed. Similarly, the wetting layer may be exposed to a
nitriding ambient and may be heated to form a nitride. Thus, a
nitride wetting layer may be formed by natural nitriding or
reactive nitridization. The oxidation/nitridation step is desired
to continue until a target RA is achieved. In some embodiments, the
RA target is nominally ten. However, other RAs or other measures of
the oxidation/nitridation may be used to determine when to
terminate the process. In some embodiments, step 104A may be
continued until the wetting layer is completely oxidized or
nitrided. For example, an oxide wetting layer may include or
consist of Fe-Ox and/or CoFe-Ox where Ox denotes an oxide. Thus, a
treated wetting layer that may be an oxide wetting layer or a
nitride wetting layer is provided.
[0038] A portion of the magnetic junction that has already been
fabricated is cryo-cooled to within a temperature range including
temperatures not greater than 250 K, via step 106A. Step 106A is
analogous to step 102 of the method 100. However, more of the
magnetic junction has been fabricated so more of the magnetic
junction is cooled. More specifically, the oxide/nitride wetting
layer is also cooled in step 106A. In some embodiments, the
temperature range includes temperature(s) of at least 50K and not
greater than 150K. In some such embodiments, the temperature range
is from at least 70K through not greater than 100K.
[0039] While the substrate for the magnetic junction is cooled
using step 106A, a boron-free magnetic layer is deposited on the
oxide/nitride wetting layer, via step 108A. Step 108A is analogous
to step 108. However, in step 108A the device is cryo-cooled. The
material(s) deposited for the boron-free magnetic layer may include
the material(s) deposited for the oxide/nitride wetting layer
deposited in step 102A. Step 108A may include depositing 3d
transition metals, their alloys and/or Heusler alloys such as
Co.sub.2 Fe, Co.sub.2 MnSi, Co.sub.2 FeMnSi, Co.sub.2 FeSi, MnGa,
and MnGe. Thus, binary, ternary and other alloys not including
boron may be deposited in step 108A. Stated differently, other
and/or additional nonmagnetic and/or magnetic materials excluding
boron may be provided in step 108A for the boron-free magnetic
layer. For example, CoX, FeX, NiX, CoFeX and/or CoFeNiX, where X is
not B, may be used. Similarly, elements such as Fe, Co, Ni and Mn
might be deposited. Thus, step 108A may include depositing at least
one of elemental Fe, elemental Co, elemental Ni, elemental Mn, an
Fe-containing alloy such as CoFe, a Co-containing alloy such as
CoFe, a Ni-containing alloy, a Mn containing alloy and a Heusler
alloy.
[0040] Thus, step 108A provides a boron-free magnetic layer
including the materials described above and that be polycrystalline
as-deposited. In addition, the boron-free magnetic layer may have a
high PMA. The perpendicular magnetic anisotropy energy of the layer
may exceed the out-of-plane demagnetization energy. Thus, the
magnetic moment (not shown) of the boron-free magnetic layer 206
may be stable perpendicular-to-plane.
[0041] Fabrication of the magnetic junction may then be completed,
via step 110. Step 110 may include annealing the layers 200 at
temperature(s) above room temperature (300K) to complete
crystallization of the boron-free magnetic layer. For example, a
rapid thermal anneal may be employed. A plasma etch may be used in
addition to or in lieu of the anneal to improve crystallinity. An
oxide layer may also be deposited on the boron-free magnetic layer.
The oxide layer may be a tunneling barrier layer or a capping
layer. Alternatively, other layers might be provided on the
boron-free magnetic layer. Further, as the boron-free magnetic
layer is part of the magnetic junction stack, the boron-free
magnetic layer as well as other layers in the device may be masked,
etched to define the magnetic junction and/or undergo other
processing.
[0042] Using the method 100A, the layers shown in FIG. 5 may be
manufactured. Thus, the method 100A may share the benefits of the
method 100. A boron-free magnetic layer 206 having a high PMA may
be fabricated. It is believed that the quality of the boron-free
magnetic layer 206 provided using the method 100 may be superior to
that provided using the method 100A. For example, the roughness of
the wetting layer 204' may be reduced for the method 100. The
wetting layer 204' may also have fewer voids for the method 100
over the method 100A. This may result in a better boron-free
magnetic layer 206 for the method 100. However, the boron-free
magnetic layer provided in step 108/108A may still exhibit improved
quality and the desired characteristics described herein. When used
in the free layer, therefore, the boron-free magnetic layer 206
formed using the method 100A may have improved stability. The
magnetoresistance of such a magnetic junction may also be improved.
Further, if the free layer consists of the boron-free magnetic
layer 206 formed in the method 100A, the free layer is
compositionally uniform. As such, switching performance of the
magnetic junction may be improved. If used in the pinned layer, the
boron-free magnetic layer 206 may also improve the PMA of such a
layer. Thus, performance a magnetic junction formed with the layer
206 fabricated using the method 100 may be improved.
[0043] FIG. 7 is a flow chart depicting an exemplary embodiment of
a method 120 for providing a magnetic junction that includes
boron-free magnetic layer(s) and that is usable in magnetic devices
such as a magnetic memory programmable using STT and/or SOT. The
magnetic junction formed is usable in a magnetic device such as a
STT-MRAM, SOT-MRAM and in a variety of electronic devices. For
simplicity, some steps may be omitted, performed in another order,
include substeps and/or combined. Further, the method 120 may start
after other steps in forming a magnetic memory have been performed.
Further, multiple magnetic junctions may be simultaneously
fabricated.
[0044] A pinned layer may be provided, via step 122. Step 122 is
performed for a bottom pinned magnetic junction (pinned layer
formed before the free layer) and for a dual magnetic junction. The
pinned layer is magnetic and may have its magnetization pinned, or
fixed, in a particular direction during at least a portion of the
operation of the magnetic junction. The pinned layer may thus be
thermally stable at operating temperatures. The pinned layer formed
in step 122 may be a simple (single) layer or may include multiple
layers. For example, the pinned layer formed in step 122 may be a
synthetic antiferromagnet (SAF) including magnetic layers
antiferromagnetically or ferromagnetically coupled through thin
nonmagnetic layer(s), such as Ru. In such a SAF, each magnetic
layer may also include multiple layers. The pinned layer may also
be another multilayer. The pinned layer formed in step 122 may have
a perpendicular anisotropy energy that exceeds the out-of-plane
demagnetization energy. Thus, the pinned layer may have its
magnetic moment oriented perpendicular to plane. Other orientations
of the magnetization of the pinned layer are possible. The pinned
layer may also include a polarization enhancement layer (PEL) at
the interface with the nonmagnetic spacer layer discussed below. In
some embodiments, step 122 is performed using the method 100. Thus,
formation of the pinned layer may include cryo-cooling the
substrate, depositing the wetting layer, oxidizing the wetting
layer and depositing a boron-free magnetic layer. Additional steps
and/or additional layers may also be provided for the pinned layer
in some embodiments. Further, the pinned layer may be deposited on
an oxide seed layer such as the layer 202.
[0045] A nonmagnetic spacer layer may be provided, via step 124.
Step 124 is performed for a bottom pinned magnetic junction and a
dual magnetic junction. In some embodiments, a crystalline MgO
tunneling barrier layer may be desired for the magnetic junction
being formed. In some embodiments, step 124 may include depositing
MgO using, for example, radio frequency (RF) sputtering. In other
embodiments, metallic Mg may be deposited and then oxidized in step
124 to provide a natural oxide of Mg. The MgO barrier
layer/nonmagnetic spacer layer may also be formed in another
manner. Other materials including but not limited to MgAlOx and
MgTiOx may be used in addition to or in lieu of MgO. Step 124 may
include annealing the portion of the magnetic junction already
formed to provide crystalline MgO tunneling barrier with a (100)
orientation for enhanced TMR of the magnetic junction.
[0046] A free layer is provided, via step 126. Step 126 includes
depositing the material(s) for the free layer. In some embodiments,
step 126 is performed using the method 100. Thus, formation of the
free layer may include or consist of cryo-cooling the substrate,
depositing the wetting layer, oxidizing the wetting layer and
depositing a boron-free magnetic layer. If steps 122 and 124 are
omitted, then the free layer may be deposited on seed layer(s). In
such embodiments, a top pinned magnetic junction is fabricated. The
seed layer(s) may be selected for various purposes including but
not limited to the desired crystal structure of the free layer,
magnetic anisotropy and/or magnetic damping of the free layer. For
example, the free layer may be provided on a seed layer such as a
crystalline MgO layer that promotes a perpendicular magnetic
anisotropy in the free layer. If a dual magnetic junction or bottom
pinned magnetic junction is fabricated, the free layer may be
formed on a nonmagnetic spacer layer provided in step 124. Thus,
the oxide layer 202 of FIGS. 2-5 may be a seed layer or a
nonmagnetic spacer/tunneling barrier layer.
[0047] A nonmagnetic spacer layer may be provided, via step 128.
Step 128 is performed if a dual magnetic junction or top pinned
magnetic junction is desired to be fabricated. If a single, bottom
pinned magnetic junction is desired, then step 128 is omitted. In
some embodiments, an additional crystalline MgO tunneling barrier
layer may be desired for the magnetic junction being formed. Step
128 may thus be performed as described above with respect to step
124.
[0048] An additional pinned layer may optionally be provided, via
step 130. Step 130 may be performed if a dual magnetic junction or
top pinned magnetic junction is desired to be fabricated. If a
single, bottom pinned magnetic junction is desired, then step 130
is omitted. In some embodiments, step 130 is performed using the
method 100. Thus, formation of the pinned layer may include
cryo-cooling the substrate, depositing the wetting layer, oxidizing
the wetting layer and depositing a boron-free magnetic layer.
[0049] Fabrication of the magnetic junction may then be completed.
For example, the capping layer(s) may be deposited and the edges of
the magnetic junction defined, for example by providing a mask on
the layers that have been deposited and ion milling the exposed
portions of the layers. In some embodiments, an ion mill may be
performed. Thus, the edges of the magnetic junction may be defined
after steps 122 through 130 are performed. Stated differently,
steps 122 through 130 may deposit the layers in the magnetic
junction stack, and the edges of the each of the junctions on the
wafer defined only after all of the layers have been provided.
Alternatively, the edges of various layers may be formed at other
times. Additional structures, such as contacts and conductive lines
may also be formed for the device in which the magnetic junction is
used.
[0050] FIG. 8 depicts an exemplary embodiment of a magnetic
junction 220 that may be fabricated using the method 120. For
clarity, FIG. 8 is not to scale. The magnetic junction 220 may be
used in a magnetic device such as a STT-MRAM, SOT-MRAM, logic
devices, other integrated circuits and, therefore, in a variety of
electronic devices. The magnetic junction 220 includes optional
seed layer(s) 222, a pinned layer 224 having a magnetic moment 225,
a nonmagnetic spacer layer 226, a free layer 228 having magnetic
moment 229, an optional additional nonmagnetic spacer layer 230,
and an optional additional pinned layer 232 having magnetic moment
233. Also shown are capping layer(s) 234. A bottom contact and a
top contact are not shown but may be formed. Similarly,
polarization enhancement and other layers may be present but are
not shown for simplicity. As can be seen in FIG. 8, the magnetic
junction 220 is a dual magnetic junction. In another embodiment,
the additional nonmagnetic spacer layer 230 and additional pinned
layer 232 might be omitted. In such an embodiment, the magnetic
junction 220 is a bottom pinned magnetic junction. Alternatively,
the pinned layer 224 and nonmagnetic spacer layer 226 might be
omitted. In such an embodiment, the magnetic junction 220 is a top
pinned magnetic junction. Optional pinning layer(s) (not shown) may
be used to fix the magnetization of the pinned layer(s) 224 and/or
232. In some embodiments, the optional pinning layer may be an AFM
layer or multilayer that pins the magnetization(s) through an
exchange-bias interaction. However, in other embodiments, the
optional pinning layer may be omitted or another structure may be
used.
[0051] In the embodiment shown in FIG. 8, one or more of the
magnetic layers 224, 228 and 232 are formed using the method 100.
Thus, the pinned layers 224 and 232 and the free layer 228 may have
their magnetic moments 225, 229 and 233 stable
perpendicular-to-plane, as shown. The magnetic junction 220 may
also be configured to allow the free layer 228 to be switched
between stable magnetic states when a write current is passed
through the magnetic junction 220. Thus, the free layer 228 may be
switchable utilizing STT when a write current is driven through the
magnetic junction 220 in a current perpendicular-to-plane (CPP)
direction. Alternatively, the magnetic junction may be configured
such that other switching mechanisms may be used. The data stored
in the magnetic junction 220, and thus the direction of
magnetization of the free layer 228, may be read by driving a read
current through the magnetic junction 220. The read current may
also be driven through the magnetic junction 220 in the CPP
direction. Thus, the magnetoresistance of the magnetic junction 220
provides the read signal.
[0052] The magnetic junction 220 may have improved performance due
to fabrication using the method 100. More specifically, the
magnetic junction 220 may enjoy the benefits described above for
the method 100. A boron-free magnetic layer having a high PMA may
be used in one or more of the layers 224, 228 and 232. When used in
the free layer 228, the boron-free magnetic layer may provide
improved stability. The magnetoresistance of such a magnetic
junction 220 may also be improved. Further, if the free layer 228
consists of the boron-free magnetic layer 206, the free layer is
compositionally uniform. As such, switching performance of the
magnetic junction 220 may be improved. If used in the pinned
layer(s) 224 and/or 232, the boron-free magnetic layer 206 may also
improve the PMA of such a layer. Thus, performance a magnetic
junction formed with the layer 206 fabricated using the method 100
may be improved.
[0053] FIG. 9 depicts an exemplary embodiment of a magnetic
junction 220A that may be fabricated using the method 120. For
clarity, FIG. 9 is not to scale. The magnetic junction 220A may be
used in a magnetic device such as a STT-MRAM, SOT-MRAM, logic
devices, other integrated circuits and, therefore, in a variety of
electronic devices. The magnetic junction 220A is analogous to the
magnetic junction 220. The magnetic junction 220A includes optional
seed layer(s) 222, a pinned layer 224A having a magnetic moment
225, a nonmagnetic spacer layer 226, a free layer 228A and optional
capping layer(s) 234 that are analogous to the layers 222, 223,
226, 228 and 234, respectively, shown in FIG. 8. The magnetic
junction 220A is a bottom pinned magnetic junction.
[0054] The magnetic junction 220A explicitly includes oxide
underlayer 240, oxide/nitride wetting layer 242 and boron-free
magnetic layer 244 corresponding to the layers 202, 204 and 206 as
part of the pinned layer 224A. The pinned layer 224A is shown as
also including high PMR layers 245. Alternatively, the pinned layer
224A may consist of the layers 240, 242 and 244. In some
embodiments, the seed layers 222 may function as the oxide
underlayer 240. Similarly, the free layer 228A includes oxide
underlayer 246, oxide/nitride wetting layer 248 and boron-free
magnetic layer 250 corresponding to the layers 202, 204 and 206.
The free layer 228A may also include high PMR layers 249.
Alternatively, the free layer 228A may consist of the layers 246,
248 and 250. In some embodiments, the layers 240, 242 and 244
and/or the layers 246, 248 and 250 may be omitted and/or in another
location.
[0055] The magnetic junction 220A may have improved performance due
to fabrication using the method 100. More specifically, the
magnetic junction 220A may have enhanced PMA, increased stability
and improved switching characteristics.
[0056] FIG. 10 depicts an exemplary embodiment of a magnetic
junction 220B that may be fabricated using the method 120. For
clarity, FIG. 10 is not to scale. The magnetic junction 220B may be
used in a magnetic device such as a STT-M RAM, SOT-MRAM, logic
devices, other integrated circuits and, therefore, in a variety of
electronic devices. The magnetic junction 220B is analogous to the
magnetic junction 220. The magnetic junction 220B includes optional
seed layer(s) 222, a free layer 228B having moment 229, a
nonmagnetic spacer layer 230, a pinned layer 232B having a magnetic
moment 225 and optional capping layer(s) 234 that are analogous to
the layers 222, 228, 230, 232 and 234, respectively, shown in FIG.
8. The magnetic junction 220B is a top pinned magnetic
junction.
[0057] The magnetic junction 220B explicitly includes oxide
underlayer 246, oxide/nitride wetting layer 248 and boron-free
magnetic layer 250 corresponding to the layers 202, 204 and 206 as
part of the free layer 228B. The free layer 228B is shown as also
including high PMR layers 245. Alternatively, the free layer 228B
may consist of the layers 246, 248 and 250. In some embodiments,
the seed layers 222 may function as the oxide underlayer 246.
Similarly, the pinned layer 232B includes oxide underlayer 252,
oxide/nitride wetting layer 254 and boron-free magnetic layer 256
corresponding to the layers 202, 204 and 206. The pinned layer 232B
may also include high PMR layers 257. Alternatively, the pinned
layer 232B may consist of the layers 252, 254 and 256. The layer
256 might be considered a PEL in some embodiments. In some
embodiments, the layers 246, 248 and 250 or the layers 252, 254 and
256 may be omitted and/or in another location.
[0058] The magnetic junction 220B may have improved performance due
to fabrication using the method 100. More specifically, the
magnetic junction 220B may have enhanced PMA, increased stability
and improved switching characteristics.
[0059] FIG. 11 depicts an exemplary embodiment of a magnetic
junction 220C that may be fabricated using the method 120. For
clarity, FIG. 11 is not to scale. The magnetic junction 220C may be
used in a magnetic device such as a STT-MRAM, SOT-MRAM, logic
devices, other integrated circuits and, therefore, in a variety of
electronic devices. The magnetic junction 220C is analogous to the
magnetic junction 220. The magnetic junction 220C includes optional
seed layer(s) 222, a pinned layer 224C having magnetic moment 225,
nonmagnetic a spacer layer 226, a free layer 228C having moment
229, a nonmagnetic spacer layer 230, a pinned layer 232C having a
magnetic moment 225 and optional capping layer(s) 234 that are
analogous to the layers 222, 224, 226, 228, 230, 232 and 234,
respectively, shown in FIG. 8. The magnetic junction 220C is a dual
magnetic junction. Thus, one of the nonmagnetic spacer layers 226
and 230 may be the main barrier layer, while the other of the
layers 226 and 230 may be a sub barrier layer.
[0060] The magnetic junction 220C explicitly includes oxide
underlayer 240, oxide/nitride wetting layer 242 and boron-free
magnetic layer 244 corresponding to the layers 202, 204 and 206 as
part of the pinned layer 224C. The pinned layer 224C is shown as
also including high PMR layers 245. Alternatively, the pinned layer
224C may consist of the layers 240, 242 and 244. In some
embodiments, the seed layers 222 may function as the oxide
underlayer 240. Similarly, the free layer 228C includes oxide
underlayer 246, oxide/nitride wetting layer 248 and boron-free
magnetic layer 250 corresponding to the layers 202, 204 and 206.
The free layer 228C is shown as also including high PMR layers 245.
Alternatively, the free layer 228C may consist of the layers 246,
248 and 250. The pinned layer 232C includes oxide underlayer 252,
oxide/nitride wetting layer 254 and boron-free magnetic layer 256
corresponding to the layers 202, 204 and 206. The pinned layer 232C
is shown as also including high PMR layers 245. Alternatively, the
pinned layer 232C may consist of the layers 252, 254 and 256. In
some embodiments, the layers 240, 242 and 244; the layers 246, 248
and 250 and/or the layers 252, 254 and 256 may be omitted and/or in
another location.
[0061] The magnetic junction 220B may have improved performance due
to fabrication using the method 100. More specifically, the
magnetic junction 220C may have enhanced PMA, increased stability
and improved switching characteristics.
[0062] Although the method and apparatus have been described in the
context of specific features, steps and components, one of ordinary
skill in the art will recognize that one or more of these features,
steps and/or components may be combined in other manners not
inconsistent with the description herein.
[0063] FIG. 12 depicts an exemplary embodiment of a memory 300 that
may use one or more of the magnetic junctions 220, 220A, 220B, 220C
and/or other magnetic junctions including boron-free magnetic layer
206. The magnetic memory 300 includes reading/writing column select
drivers 302 and 306 as well as word line select driver 304. Note
that other and/or different components may be provided. The storage
region of the memory 300 includes magnetic storage cells 310. Each
magnetic storage cell includes at least one magnetic junction 312
and at least one selection device 314. In some embodiments, the
selection device 314 is a transistor. The magnetic junctions 312
may be one of the magnetic junctions 220, 220A, 220B, 220C and/or
other magnetic junctions including boron-free magnetic layer 206.
Although one magnetic junction 312 is shown per cell 310, in other
embodiments, another number of magnetic junctions 312 may be
provided per cell. As such, the magnetic memory 300 may enjoy the
benefits described above.
[0064] A method and system for providing a magnetic junction and a
memory fabricated using the magnetic junction has been described.
The method and system have been described in accordance with the
exemplary embodiments shown, and one of ordinary skill in the art
will readily recognize that there could be variations to the
embodiments, and any variations would be within the spirit and
scope of the method and system. Accordingly, many modifications may
be made by one of ordinary skill in the art without departing from
the spirit and scope of the appended claims.
* * * * *