U.S. patent application number 15/968514 was filed with the patent office on 2019-09-05 for vertical spin orbit torque devices.
The applicant listed for this patent is Samsung Electronics Co., LTD.. Invention is credited to Dmytro Apalkov, Vladimir Nikitin.
Application Number | 20190273202 15/968514 |
Document ID | / |
Family ID | 67767769 |
Filed Date | 2019-09-05 |
![](/patent/app/20190273202/US20190273202A1-20190905-D00000.png)
![](/patent/app/20190273202/US20190273202A1-20190905-D00001.png)
![](/patent/app/20190273202/US20190273202A1-20190905-D00002.png)
![](/patent/app/20190273202/US20190273202A1-20190905-D00003.png)
![](/patent/app/20190273202/US20190273202A1-20190905-D00004.png)
![](/patent/app/20190273202/US20190273202A1-20190905-D00005.png)
![](/patent/app/20190273202/US20190273202A1-20190905-D00006.png)
![](/patent/app/20190273202/US20190273202A1-20190905-D00007.png)
![](/patent/app/20190273202/US20190273202A1-20190905-D00008.png)
![](/patent/app/20190273202/US20190273202A1-20190905-D00009.png)
![](/patent/app/20190273202/US20190273202A1-20190905-D00010.png)
View All Diagrams
United States Patent
Application |
20190273202 |
Kind Code |
A1 |
Nikitin; Vladimir ; et
al. |
September 5, 2019 |
VERTICAL SPIN ORBIT TORQUE DEVICES
Abstract
A magnetic device and method for programming the magnetic device
are described. The magnetic device includes a plurality of magnetic
junctions and at least one spin-orbit interaction (SO) active layer
having a plurality of sides. The SO active layer(s) carry a current
in direction(s) substantially perpendicular to the plurality of
sides. Each of the magnetic junction(s) is adjacent to the sides
and substantially surrounds a portion of the SO active layer. Each
magnetic junction includes a free layer, a reference layer and a
nonmagnetic spacer layer between the pinned and free layers. The SO
active layer(s) exert a SO torque on the free layer due to the
current passing through the SO active layer(s). The free layer is
switchable between stable magnetic states. The free layer may be
written using the current and, in some aspects, another current
driven through the magnetic junction.
Inventors: |
Nikitin; Vladimir;
(Campbell, CA) ; Apalkov; Dmytro; (San Jose,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Samsung Electronics Co., LTD. |
Gyeonggi-do |
|
KR |
|
|
Family ID: |
67767769 |
Appl. No.: |
15/968514 |
Filed: |
May 1, 2018 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
62637596 |
Mar 2, 2018 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G11C 11/155 20130101;
H01F 10/3286 20130101; G11C 11/1673 20130101; H01L 27/228 20130101;
G11C 11/1659 20130101; H01L 43/06 20130101; H01L 43/12 20130101;
H01L 43/02 20130101; H01F 10/3254 20130101; H01F 10/329 20130101;
H01L 43/08 20130101; G11C 11/1675 20130101; H01F 10/3272 20130101;
G11C 11/161 20130101 |
International
Class: |
H01L 43/08 20060101
H01L043/08; H01L 27/22 20060101 H01L027/22; H01L 43/02 20060101
H01L043/02; G11C 11/16 20060101 G11C011/16; H01F 10/32 20060101
H01F010/32; H01L 43/12 20060101 H01L043/12 |
Claims
1. A magnetic device comprising: at least one spin-orbit
interaction (SO) active layer having a plurality of sides, the at
least one SO active layer carrying a current in at least one
direction substantially perpendicular to the plurality of sides;
and at least one magnetic junction, each of the at least one
magnetic junction being adjacent to the plurality of sides and
substantially surrounding a portion of the SO active layer, each of
the at least one magnetic junction including a free layer, a
reference layer and a nonmagnetic spacer layer, the nonmagnetic
spacer layer being between the reference layer and the free layer,
the at least one SO active layer exerting a SO torque on the free
layer due to the current passing through the at least one SO active
layer, the free layer being switchable between a plurality of
stable magnetic states.
2. The magnetic device of claim 1 wherein each of the at least one
magnetic junction further includes: a reference layer; and a
nonmagnetic spacer layer, the nonmagnetic spacer layer being
between the reference layer and the free layer.
3. The magnetic device of claim 1 further comprising: a substrate,
each of the at least one magnetic junction forming a nonzero angle
with the substrate.
4. The magnetic device of claim 3 wherein the nonzero angle is
substantially ninety degrees.
5. The magnetic device of claim 1 wherein each of the at least one
magnetic junction has a substantially circular cross-section.
6. The magnetic device of claim 1 wherein the plurality of stable
magnetic states of the free layer are selected from a first stable
axis along the at least one direction; a second stable state
parallel to the plurality of sides and a radial direction
substantially perpendicular to the plurality of sides.
7. The magnetic device of claim 1 wherein the SO active layer has a
first resistivity and is part of a line including a core having a
second resistivity, the SO active layer substantially surrounding
the core, the first resistivity being less than the second
resistivity.
8. The magnetic device of claim 1 wherein the at least one magnetic
junction is a single magnetic junction and wherein the magnetic
device further includes: a selection device coupled with the at
least one SO active layer.
9. The magnetic device of claim 8 wherein the selection device is
selected from a planar transistor and a three-dimensional
transistor.
10. The magnetic device of claim 7 further comprising: a diode
coupled with the reference layer.
11. The magnetic device of claim 1 wherein the at least one
magnetic junction is a plurality of magnetic junctions.
12. The magnetic device of claim 11 further comprising: at least
one isolation device interleaved with the plurality of magnetic
junctions.
13. A magnetic device comprising: a plurality of spin-orbit
interaction (SO) active layers, each of the plurality of SO active
layers having a plurality of sides and carrying a current in at
least one direction substantially perpendicular to the plurality of
sides; at least one magnetic junction coupled with each of the
plurality of SO active layers, each of the at least one magnetic
junction being adjacent to the plurality of sides and substantially
surrounding a portion each of the plurality of SO active layers,
each of the at least one magnetic junction including a free layer,
a reference layer and a barrier layer, the barrier layer being
between the reference layer and the free layer, each of the
plurality of SO active layers exerting a SO torque on the free
layer due to the current passing through each of the plurality of
SO active layers, the free layer being switchable between a
plurality of stable magnetic states, the plurality of stable
magnetic states of the free layer being selected from a first
stable axis along the at least one direction; a second stable state
parallel to the plurality of sides and a radial direction
substantially perpendicular to the plurality of sides; and a
plurality of lines coupled with the reference layer of the at least
one magnetic junction.
14. A method for writing to at least one magnetic junction of a
magnetic device comprising: driving a spin-orbit interaction (SO)
write current through at least one SO active layer having a
plurality of sides, the at least one SO active layer carrying the
SO write current in at least one direction substantially
perpendicular to the plurality of sides, the at least one magnetic
junction, each of the at least one magnetic junction being adjacent
to the plurality of sides and substantially surrounding a portion
of the SO active layer, each of the at least one magnetic junction
including at least a free layer, a reference layer and a
nonmagnetic spacer layer, the nonmagnetic spacer layer being
between the reference layer and the free layer, the at least one SO
active layer exerting a SO torque on the free layer due to the SO
write current passing through the at least one SO active layer.
15. The method of claim 14 wherein each of the at least one
magnetic junction further includes a reference layer and a
nonmagnetic spacer layer, the nonmagnetic spacer layer being
between the reference layer and the free layer.
16. The method of claim 15 further comprising: driving a spin
transfer torque (STT) write current through the at least one
magnetic junction while the SO write current is driven through the
SO active layer, a final magnetic state of the free layer being set
by the STT write current.
17. The method of claim 15 further comprising: driving a spin
transfer torque (STT) write current through the at least one
magnetic junction after the SO write current starts to be driven
through the SO active layer.
18. The method of claim 15 further comprising: driving a spin
transfer torque (STT) write current through the at least one
magnetic junction after the SO write current terminates.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of provisional Patent
Application Ser. No. 62/637,596, filed Mar. 2, 2018, entitled
VERTICAL SPIN ORBIT TORQUE DEVICES INCLUDING MAGNETIC RANDOM ACCESS
MEMORY, 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. Some magnetic memories write to the
magnetic material using a current. One such magnetic memory
programs magnetic junctions using spin-orbit interaction (SO)
torque.
[0003] SO torque-based memories, such as a SO torque magnetic
random-access memory (SOT-MRAM), utilize conventional magnetic
tunneling junctions (MTJs) in conjunction with a line having a high
spin-orbit interaction (hereinafter SO line). The conventional MTJ
includes a pinned (or reference) layer, a free layer and a
tunneling barrier layer between the pinned and free layers. The MTJ
typically resides on a substrate and may include seed and capping
layer(s) as well as an antiferromagnetic (AFM) layer. 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 reference layer and
free layer may have their magnetizations oriented perpendicular to
the plane of the layers (perpendicular-to-plane) or in the plane of
the layers (in-plane). The SO line is adjacent to the free layer of
the conventional MTJ. The high spin-orbit interaction may be due to
a bulk effect of the material itself (spin Hall effect), due to
interfacial interactions (Rashba effect), some other effect and/or
some combination thereof.
[0004] In conventional SO memories, writing is performed by driving
a current in-plane (CIP) through the SO line. If the free layer
magnetic moment is stable in-plane, then the in-plane SO torque
alone can switch the free layer between stable states. Thus, a
current driven through the adjacent SO line generates an SO torque
that may switch the direction of magnetization of the free layer
without additional switching mechanism(s). In contrast, if the free
layer has a magnetic moment that is stable perpendicular-to-plane,
then an additional torque is used. Since the spin orbit torque is
in-plane, in order to reliably switch the magnetic moment using the
in-plane current, a symmetry breaking additional torque is
required, and can be achieved by either modest external magnetic
field, an in-stack magnetic bias, or STT torque through MgO
barrier. The in-plane current develops an SO torque, which can be
used to rotate the free layer magnetic moment from vertical to near
in-plane direction. Switching to the desired direction is completed
using the external magnetic bias or STT current. For example, the
external magnetic field, an additional AFM layer or biasing
structure may magnetically bias the free layer to complete
switching to the desired state.
[0005] Although the conventional magnetic junction may be written
using spin transfer and used in a spin transfer torque random
access memory (STT-RAM), there are drawbacks. In general, SO torque
is not an efficient mechanism for switching the free layer. Stated
differently, the SO angle (measure of this efficiency of SO torque)
is generally small. Thus, a high write current may be required for
writing. In addition, the spin current in regions not adjacent to
the magnetic is not used in writing. Thus, this spin current may be
wasted. Memory cells using SO torque may have a large footprint
because a three-terminal device may be used for write and read
operations. Perpendicular magnetic moments in the layers of the
magnetic junction may also not be usable in some embodiments. Thus,
scalability may be limited. Consequently, a mechanism for improving
SO torque magnetic devices is still desired.
BRIEF SUMMARY OF THE INVENTION
[0006] A magnetic device and method for programming the magnetic
device are described. The magnetic device includes a plurality of
magnetic junctions and at least one spin-orbit interaction (SO)
active layer having a plurality of sides. The SO active layer(s)
carry a current in direction(s) substantially perpendicular to the
plurality of sides. Each of the magnetic junction(s) is adjacent to
the sides and substantially surrounds a portion of the SO active
layer. Each magnetic junction includes a free layer, a reference
layer and a nonmagnetic spacer layer between the pinned and free
layers. The SO active layer(s) exert a SO torque on the free layer
due to the current passing through the SO active layer(s). The free
layer is switchable between stable magnetic states. The free layer
may be written using the current and, in some aspects, another
current driven through the magnetic junction.
[0007] Performance of magnetic devices using magnetic junctions
written using SO torque may be improved. For example, the interface
for the spin current may be enhanced, the design may be scalable,
fewer selection devices might be used, switching time might be
reduced, read and write may be separately optimized, and/or
breakdown of a tunneling barrier used in some aspects may be
reduced.
BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS
[0008] FIGS. 1A-1C depict perspective, cross-section and top views
of an exemplary embodiment of a magnetic device including vertical
magnetic junctions programmable using SO torque.
[0009] FIGS. 2A-2C depict exemplary embodiments of the magnetic
moment of a vertical magnetic junction.
[0010] FIGS. 3A-3B depict exemplary embodiments the magnetic moment
of a free layer after switching using SO torque.
[0011] FIG. 4 depicts a top view of another exemplary embodiment of
a magnetic device including vertical magnetic junctions
programmable using SO torque.
[0012] FIG. 5 depicts a top view of another exemplary embodiment of
a magnetic device including vertical magnetic junctions
programmable using SO torque.
[0013] FIG. 6 depicts a top view of another exemplary embodiment of
a magnetic device including vertical magnetic junctions
programmable using SO torque.
[0014] FIGS. 7A-7B depict perspective and top views of an exemplary
embodiment of a magnetic device including vertical magnetic
junctions programmable using SO torque.
[0015] FIGS. 8A-8C depict perspective, cross-section and top views
of an exemplary embodiment of a magnetic device including vertical
magnetic junctions programmable using SO torque.
[0016] FIGS. 9A-9F depict cross-sectional views of an exemplary
embodiment of a magnetic device including vertical magnetic
junctions programmable using SO torque during writing and
reading.
[0017] FIG. 10 depicts a perspective view of another exemplary
embodiment of a magnetic memory including vertical magnetic
junctions programmable using SO torque.
[0018] FIG. 11 depicts a perspective view of another exemplary
embodiment of a magnetic memory including vertical magnetic
junctions programmable using SO torque.
[0019] FIG. 12 depicts a perspective view of another exemplary
embodiment of a magnetic memory including vertical magnetic
junctions programmable using SO torque.
[0020] FIG. 13 depicts a circuit diagram of another exemplary
embodiment of a magnetic memory including vertical magnetic
junctions programmable using SO torque.
[0021] FIG. 14 depicts a circuit diagram of another exemplary
embodiment of a magnetic memory including vertical magnetic
junctions programmable using SO torque.
[0022] FIG. 15 depicts a perspective view of another exemplary
embodiment of a magnetic device including multiple vertical
magnetic junctions programmable using SO torque.
[0023] FIG. 16 depicts a perspective view of another exemplary
embodiment of a magnetic device including multiple vertical
magnetic junctions programmable using SO torque.
[0024] FIG. 17 is a flow chart depicting an exemplary embodiment of
a method for providing a magnetic device programmable using SO
torque in and including vertical magnetic junctions.
[0025] FIG. 18 is a flow chart depicting an exemplary embodiment of
a method for programming a magnetic junction programmable using SO
torque and including vertical magnetic junctions.
DETAILED DESCRIPTION OF THE INVENTION
[0026] The exemplary embodiments relate to magnetic junctions
usable in magnetic devices, such as magnetic memories and/or logic
devices, and the devices using such magnetic junctions. The
magnetic memories may include magnetic random-access memories
(MRAMs) and may be used in electronic devices employing nonvolatile
memory. Such 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 less 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, substeps and/or 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.
[0027] 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 orbit interaction
phenomenon, 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. However, 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 having particular layers. However,
one of ordinary skill in the art will readily recognize that
magnetic junctions 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. 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.
[0028] 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.
[0029] 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.
[0030] A magnetic device and method for programming the magnetic
device are described. The magnetic device includes a plurality of
magnetic junctions and at least one spin-orbit interaction (SO)
active layer having a plurality of sides. The SO active layer(s)
carry a current in direction(s) substantially perpendicular to the
plurality of sides. Each of the magnetic junction(s) is adjacent to
the sides and substantially surrounds a portion of the SO active
layer. Each magnetic junction includes a free layer, a reference
layer and a nonmagnetic spacer layer between the pinned and free
layers. The SO active layer(s) exert a SO torque on the free layer
due to the current passing through the SO active layer(s). The free
layer is switchable between stable magnetic states. The free layer
may be written using the current and, in some aspects, another
current driven through the magnetic junction.
[0031] FIGS. 1A-1C depict perspective, cross-section and top views
of an exemplary embodiment of a magnetic device 100 including a
vertical magnetic junction 110 programmable using SO torque. For
clarity, FIGS. 1A-1C are not to scale. In addition, portions of the
magnetic device 100 such as bit lines, row and column selectors are
not shown. The magnetic device 100 includes magnetic junctions 110
and a spin-orbit interaction (SO) active layer 130 analogous to the
SO line described above. In some embodiments, selection devices
(not shown) and other components may also be included. Not shown is
an optional insertion layer that may be between the SO active layer
130 and the magnetic junction 110. Typically, multiple magnetic
junctions 110 and multiple SO active layer 130 may be included in
the magnetic device 100. The magnetic device 100 may be used in a
variety of electronic devices.
[0032] The magnetic junction 110 includes a free layer 112, a
nonmagnetic spacer layer 114 and a reference layer 116. The
magnetic junction 110 may also include optional polarization
enhancement layer(s) (PEL(s)) having a high spin polarization. For
example, a PEL might include Fe, CoFe and/or CoFeB. The PEL may be
between the reference layer 116 and the nonmagnetic spacer layer
114 and/or between the nonmagnetic spacer layer 114 and the free
layer. Contact, optional seed layer(s) and optional capping
layer(s) may be present but are not shown for simplicity. An
optional pinning layer (not shown) may be used to fix the
magnetization (not shown) of the reference layer 116. The optional
pinning layer may be an AFM layer or multilayer that pins the
magnetization (not shown) of the reference layer 116 by an
exchange-bias interaction. However, in other embodiments, the
optional pinning layer may be omitted or another structure may be
used. In other embodiments, discussed below, the reference layer
116 and nonmagnetic spacer layer 114 might be omitted.
[0033] Also not shown in FIGS. 1A-1C is the underlying substrate on
which the components 110 and 130 are grown. In some embodiments,
the substrate is in the x-y plane. In such an embodiment, the z
direction is perpendicular to the plane and vertical. In such
embodiments, the magnetic junction 110 has the plane of its layers
112, 114 and 116 perpendicular to the plane of the substrate.
Stated differently, the interfaces between the layers 112, 114 and
116 would be at a nonzero angle from the substrate surface (not
shown). In the embodiment shown, if the substrate is in the x-y
plane, the interfaces are substantially perpendicular to the
substrate. Consequently, the magnetic junction 110 may be
considered to be a vertical magnetic junction. In other
embodiments, the interfaces between the layers 112, 114 and 116 may
be tilted with respect to the substrate. For example, if the
magnetic junction 110 is conical in profile instead of cylindrical
or if the magnetic junction is cylindrical but has an axis that is
not parallel to the z-axis. In other embodiments, the substrate
oriented in another manner. For example, the substrate might be in
the x-z plane or the y-z plane. In such embodiments, the axis of
the SO active layer 130 is horizontal. In such embodiments, a
portion of the magnetic junction 110 lies below the SO active layer
130. However, such embodiments may be difficult to fabricate.
[0034] The reference layer 116 is magnetic and may be a multilayer.
For example, the reference layer 116 may be a synthetic
antiferromagnet (SAF) including multiple ferromagnetic layers
interleaved with and sandwiching nonmagnetic layer(s) such as Ru.
Other multilayers may be used in the reference layer 116. For
example, the reference layer 116 may include or consist of one or
more of CoFe, CoFeB, FeB, and/or CoPt. Note that as used herein
CoFeB, FeB, CoB, CoPt and other materials listed denote alloys in
which the stoichiometry is not indicated. For example, CoFeB may
include (CoFe).sub.1-xB.sub.x, where x is greater than or equal to
zero and less than or equal to 0.5 as-deposited. For example, x may
be at least 0.2 and not more than 0.4. Other materials and/or
structures are possible for the reference layer 116. The magnetic
moment of the reference layer 116 may take on various
configurations that are discussed below.
[0035] The nonmagnetic NM spacer layer 114 is between reference
layer 116 and the free layer 112. The nonmagnetic spacer layer 114
may be a tunneling barrier layer. For example, the nonmagnetic
spacer layer 114 may include or consist of MgO, aluminum oxide
and/or titanium oxide. The MgO layer may be crystalline and have a
200 orientation for enhanced tunneling magnetoresistance (TMR). In
other embodiments, the nonmagnetic spacer layer 114 may be a
different tunneling barrier layer, may be a conductive layer or may
have another structure.
[0036] The free layer 112 is magnetic and may be a multilayer. The
free layer 112 may be a SAF or other multilayer. For example, the
free layer 112 may include or consist of one or more of CoFe, CoFeB
and/or Fe. The magnetic moment of the free layer 112 may have
various stable states that are discussed below. The free layer is
adjacent to the sides of the SO active layer 130. In the embodiment
shown, the sides of the SO active layer 130 are cylindrical and
perpendicular to the x-y plane. The free layer 112 is substantially
perpendicular to the x-y plane and cylindrical. In the embodiment
shown in FIGS. 1A-1C, the free layer 112 adjoins, or shares an
interface with, at least a portion of the sides of the SO active
layer 130. In another embodiment, a thin layer may be inserted
between the free layer 112 and the SO active layer 130. For
example, such a layer may moderate/enhance SO torque. Although
shown in FIGS. 1A-1C as completely surrounding the sides of the SO
active layer 130 that are adjacent to the magnetic junction 110, in
other embodiments the free layer 112 may not completely enclose the
SO active layer 130. For example, there may be a section missing
from the magnetic junction 110 shown in FIGS. 1A-1C. In some
embodiments, for example, not more than half of the magnetic
junction on one side of the SO active layer 130 may be omitted.
However, a magnetic junction 110 that completely surrounds a
portion of the sides of the SO active layer 130 is generally
desired.
[0037] The magnetic junction 110 is configured such that the free
layer 112 is switchable between stable magnetic states using a
write current which is passed through the SO active layer 130 along
the axis of the SO active layer 130 (e.g. along the z axis/.+-.z
direction in FIGS. 1A-1C). Thus, the free layer 112 is programmable
using SO torque. In some embodiments, the free layer 112 is
programmable in the absence of a write current driven through the
magnetic junction 110. Stated differently, spin transfer torque
(STT) is not needed to write to the magnetic junction 110 in some
embodiments. In alternate embodiments, however, a modest current
driven through the magnetic junction 110 and/or an external
magnetic field/magnetic bias may be used to assist in switching the
free layer magnetic moment.
[0038] The SO active layer 130 is a layer that has a strong
spin-orbit interaction and is used in switching the magnetic moment
(not shown) of the free layer 112. For example, the SO active layer
may include or consist of materials having a large SO angle with
large spin-orbit coupling such as one or more of T, W, IrMn, or Pt,
or a topological insulator, such as BiTe, BiSe, BiSb, and/or SbTe.
Although termed a "layer", in the embodiment shown in FIGS. 1A-1C,
the current carrying line 130 consists of the SO active material.
Thus, when used in connection with the SO materials, the term layer
need not imply a particular shape or orientation to the substrate.
For example, the SO active layer 130 need not be a thin,
rectangular or planar. Although the line 130 consists of the SO
active layer 130 in FIGS. 1A-1C, in other embodiments, the line 130
may include other materials. For example, a higher conductivity
material may replace or supplement the SO active layer 130 in
regions distal from the magnetic junction 110. In other
embodiments, a higher resistivity/lower conductivity core might be
used. A write current is driven along the length of the SO active
layer 130 in the +z direction or the -z direction. This write
current gives rise to an attendant SO interaction, which results in
a spin-orbit torque used in writing to the free layer 112.
[0039] As discussed above, the stable magnetic states of the free
layer 112, as well as the reference layer 116, may take on various
configurations. FIGS. 2A-2C depict exemplary embodiments of
magnetic devices 100 and the magnetic moment of vertical magnetic
junction 110A, 110B and 110C. The magnetic junctions 110A, 110B and
110C are analogous to the magnetic junction 110. The magnetic
junction 110A includes free layer 112A, nonmagnetic spacer layer
114 and reference layer 116A that are analogous to the free layer
112, nonmagnetic spacer layer 114 and reference layer 116,
respectively. Consequently, the structure, function and materials
used in the layers 112A, 114 and 116A are analogous to those for
the layers 112, 114 and 116. However, the magnetic moments 113A and
117A of the free layer 112A and reference layer 116A, respectively,
are explicitly shown. The reference layer magnetic moment 117A is
along the z-axis. The free layer stable states are along the
+z-direction and the -z-direction. Stated differently, the free
layer 112 has its easy axis parallel to the z-axis shown in FIG.
1A. The magnetic device 100A may have improved scalability, may
have fast switching (e.g. less than 0.5 nanoseconds) and may be
thermally stable, but may require large current densities for
switching in some embodiments.
[0040] The magnetic junction 110B includes free layer 112B,
nonmagnetic spacer layer 114 and reference layer 116B that are
analogous to the free layer 112, nonmagnetic spacer layer 114 and
reference layer 116, respectively. Consequently, the structure,
function and materials used in the layers 112B, 114 and 116B are
analogous to those for the layers 112, 114 and 116. However, the
magnetic moments 113B and 117B of the free layer 112B and reference
layer 116B, respectively, are explicitly shown. The reference layer
magnetic moment 117B circulates around the z-axis and, therefore,
around the SO active layer 130. The free layer stable states also
circulate around the z-axis. The magnetic device 100B may have
improved scalability, may use lower current densities for switching
(e.g. less than 3 MA/cm.sup.2) and may be thermally stable, but may
require larger switching times (e.g. greater than 10
nanoseconds).
[0041] The magnetic junction 110C includes free layer 112C,
nonmagnetic spacer layer 114 and reference layer 116C that are
analogous to the free layer 112, nonmagnetic spacer layer 114 and
reference layer 116, respectively. Consequently, the structure,
function and materials used in the layers 112C, 114 and 116C are
analogous to those for the layers 112, 114 and 116. However, the
magnetic moments 113C and 117C of the free layer 112C and reference
layer 116C, respectively, are explicitly shown. The reference layer
magnetic moment 117C is radial. In the embodiment shown, the moment
117C is toward the z-axis. In another embodiment, the moment 117C
might be radial away from the z-axis. Similarly, the free layer
stable states are also radial. The magnetic device 100C may deliver
intermediate performance. For example, the magnetic device 100C
have improved scalability, may use interfacial perpendicular
magnetic anisotropy (I-PMA) for improved thermal stability, may use
intermediate current densities (e.g. greater than 20 MA/cm.sup.2)
and may have somewhat smaller switching times (e.g. <1
nanosecond), but may be less thermally stable.
[0042] Thus, three particular configurations of magnetic moments
are shown in magnetic junctions 110A, 110B and 110C. In another
embodiment, other configurations might be used.
[0043] Referring back to FIGS. 1A-1C, the magnetic junction 110 may
be read in a conventional manner. Thus, a read current insufficient
to program the magnetic junction 110 using STT may be driven
through the magnetic junction 110 in the direction perpendicular to
at least some of the interfaces between the layers 112, 114 and
116. In the embodiment shown, the current may be driven radially
(perpendicular to the z-axis) or in another direction such as along
the y axis or along the x-axis. The resistance of the magnetic
junction 110 is based on the orientation between the free layer
magnetic moment and the reference layer magnetic moment. Thus, data
may be read from the magnetic junction 110 by determining the
resistance of the magnetic junction 110. The magnetic junctions
110A, 110B and 110C may be read in an analogous manner.
[0044] In programming the magnetic junction 110, however, a write
current is driven through the SO active layer 130 and substantially
perpendicular to the sides of the SO active layer 130 adjacent to
the free layer 112. In the embodiment shown, this is along the z
axis. Based on the direction of current, spins polarized in
opposite directions may drift to opposing sides of the SO active
layer 130. Because the free layer 112 and magnetic junction 110
substantially surround the sides of the SO active layer 130, all of
these polarized spins may be used in writing to the free layer 112.
In some embodiments, the stable magnetic states of the free layer
112 are configured such that the SO torque due to these spins can
switch the magnetic state of the free layer 112.
[0045] For example, FIGS. 3A-3B depict exemplary embodiments of the
magnetic moment of a free layer in the magnetic junction 100B after
switching using SO torque. As discussed above, the free layer 112B
has stable states circulating around the z-axis (the SO active
layer 130). Thus, FIGS. 3A-3B essentially depict the magnetic
junction 110 during writing if the magnetic moments circulate
around the SO active layer 130. FIG. 3A depicts the magnetic device
100/100B when the current is driven through the SO active layer 130
out of the plane of the page. Thus, current density Jc+ is shown.
Because of the SO effect, spins migrate to the sides of the SO
active layer 130, as shown. The spins on one side of the SO active
layer 130 have opposite polarization to spins on the opposite side
of the SO active layer 130. These spins have exerted an SO torque
on the free layer 112, causing the free layer magnetic moment 113B'
to be in the direction shown.
[0046] In contrast, FIG. 3B depicts the magnetic device 100/100B
when the current is driven through the SO active layer 130 into the
plane of the page. Thus, current density Jc- is shown. Because of
the SO effect, spins migrate to the sides of the SO active layer
130, as shown. The spins on one side of the SO active layer 130
still have opposite polarization to spins on the opposite side of
the SO active layer 130. However, the orientations have flipped.
These spins have exerted an SO torque on the free layer 112,
causing the free layer magnetic moment 113B'' to be in the
direction shown. Thus, in the embodiment shown in FIGS. 3A and 3B,
the free layer 112 may be programmed using only an SO current
Jc+/Jc- through the SO active layer 130. In other embodiments, the
programming might be assisted by an additional current and/or a
magnetic field. For example, an STT current may be driven through
the magnetic junction 110. Such a mechanism for programming could
be used with the magnetic junctions 110B, 110C, and/or 110D having
the stable states of the free layer magnetic moment circulating
around the z-axis, oriented radially with respect to the z-axis or
along the z-axis. In such embodiments, the STT current may be used
to select a final direction of the magnetic moment. Thus, a more
modest STT current may be used to switch the free layer 112 in such
embodiments.
[0047] The magnetic devices 100, 100A, 100B and 100C may have
improved performance. The free layer 112/112A/112B/112C may be
programmed using SO torque and a current driven through the SO
active layer 130. Because no STT write current is driven through
the magnetic junction 110 for programming, damage to the magnetic
junction 110 may be avoided. For example, breakdown of the
tunneling barrier layer 140 may be circumvented. Even if an STT
write current is driven through the magnetic junction
110/110A/110B/110C, the magnitude of the current may be smaller.
Thus, damage to the magnetic junction 110/110A/110B/110C may be
reduced or prevented. Moreover, the interface for the SO torque to
act on the free layer 112/112A/112B/112C may be enhanced. As such,
a smaller write current may be driven through the SO active layer
130 while still writing to the magnetic junction
110/110A/110B/110C. The configuration of the magnetic junction
110/110A/110B/110C and SO active layer 130 may be more scalable and
switching time reduced. Writing may be primarily achieved using a
current through the SO active layer, while reading performed using
a current through the magnetic junction. As a result, read and
write may be separately optimized.
[0048] FIGS. 4-6 depict top views of other exemplary embodiment of
magnetic devices 100D, 100E and 100F, respectively, including
vertical magnetic junctions 110D, 110E and 110F programmable using
SO torque and SO active layer 130D, 130E and 130F. The magnetic
junctions 110D, 110E and 110F are analogous to the magnetic
junctions 110, 110A, 110B and 110C. The magnetic junction 110D
includes free layer 112D, nonmagnetic spacer layer 114D and
reference layer 116D that are analogous to the free layer 112,
nonmagnetic spacer layer 114 and reference layer 116, respectively.
Consequently, the structure, function and materials used in the
layers 112D, 114 and 116D are analogous to those for the layers
112, 114 and 116. Similarly, the SO active layer 130D is analogous
to the SO active layer 130. Consequently, the structure, function
and materials used in the SO active layer 130D are analogous to
those used in the SO active layer 130. The magnetic junction 110D
and SO active layer 130D are elliptical in footprint instead of
circular. Thus, the magnetic device 100 is not limited to a
circular footprint.
[0049] The magnetic junction 110E includes free layer 112E,
nonmagnetic spacer layer 114E and reference layer 116E that are
analogous to the free layer 112, nonmagnetic spacer layer 114 and
reference layer 116, respectively. Consequently, the structure,
function and materials used in the layers 112E, 114 and 116E are
analogous to those for the layers 112, 114 and 116. Similarly, the
SO active layer 130E is analogous to the SO active layer 130.
Consequently, the structure, function and materials used in the SO
active layer 130E are analogous to those used in the SO active
layer 130. The magnetic junction 110E and SO active layer 130E are
square in footprint instead of circular. Thus, the magnetic device
100 is not limited to a circular footprint. In addition, an
interlayer 118 is shown. This interlayer 118 resides between the SO
active layer 130E and the free layer 112E. The layer 118 may be
used to moderate (enhance and/or decrease) interaction between the
free layer 112E and the SO active layer 130E. For example, the SO
torque may be enhanced.
[0050] The magnetic junction 110F includes free layer 112F,
nonmagnetic spacer layer 114F and reference layer 116F that are
analogous to the free layer 112, nonmagnetic spacer layer 114 and
reference layer 116, respectively. Consequently, the structure,
function and materials used in the layers 112F, 114 and 116F are
analogous to those for the layers 112, 114 and 116. Similarly, the
SO active layer 130F is analogous to the SO active layer 130.
Consequently, the structure, function and materials used in the SO
active layer 130F are analogous to those used in the SO active
layer 130. The magnetic junction 110E and SO active layer 130F are
rectangular in footprint instead of circular. In addition, the
magnetic junction 110F is shown as not completely surrounding the
SO active layer 130F. Instead, aperture or slot 119 is present.
However, as discussed above, in generally, it is desirable for the
magnetic junction to surround the SO active layer in order to
increase the area available for interaction via SO torque.
[0051] FIGS. 7A-7B depict perspective and top views of another
exemplary embodiment of a magnetic device 100G including vertical
magnetic junction(s) 110G programmable using SO torque. The
magnetic junction 100G is analogous to the magnetic junctions 110,
110A, 110B, 110C, 110D, 110E and 110F. The magnetic junction 110E
includes free layer 112, nonmagnetic spacer layer 114 and reference
layer 116 that are analogous to the free layer 112, nonmagnetic
spacer layer 114 and reference layer 116, respectively.
Consequently, the structure, function and materials used in the
layers 112, 114 and 116 of the magnetic junction 110G are analogous
to those for the layers 112, 114 and 116 of the magnetic
junction(s) 110, 110A, 110B, 110C, 110D, 110E and 110F. Similarly,
the SO active layer 130e is analogous to the SO active layer 130.
Consequently, the structure, function and materials used in the SO
active layer 130E are analogous to those used in the SO active
layer 130.
[0052] However, the line 131 includes both the SO active layer 130G
and a core 132. The core 132 may have a lower conductivity/higher
resistivity than the SO active layer 130G. For example, the core
132 may be formed of material(s) including but not limited to
polysilicon, SiN and/or SiO.
[0053] The magnetic device 100G may share the benefits of the
magnetic devices 100, 100A, 100B, 100C, 100D, 100E and/or 100F. In
addition, the current may be preferentially carried through the SO
active layer 130G, closer to the interface with the free layer 112.
As a result, the SO active layer 130G and the line 131 may have
improved efficiency in delivering SO torque to the free layer 112.
Thus, performance of the magnetic device 100G may be further
improved.
[0054] FIGS. 8A-8C depict perspective, cross-section and top views
of an exemplary embodiment of a magnetic device 100H including a
vertical magnetic junction 110H programmable using SO torque. For
clarity, FIGS. 8A-8C are not to scale. In addition, portions of the
magnetic device 100H such as bit lines, row and column selectors
are not shown. The magnetic device 100H includes magnetic junctions
110H and a spin-orbit interaction (SO) active layer 130 analogous
to the magnetic junction 110, 110A, 110B, 110C, 110D, 110E, 110F.
and/or 110G and SO active layer 130 and/or 130G described above. In
some embodiments, selection devices (not shown) and other
components may also be included. Not shown is an optional
interlayer, such as layer 118, that may be between the SO active
layer 130 and the magnetic junction 110H. Typically, multiple
magnetic junctions 110H and multiple SO active layer 130 may be
included in the magnetic device 100H. The magnetic device 100H may
be used in a variety of electronic devices.
[0055] The magnetic junction 110H includes a free layer 112 that is
analogous to the free layer 112 of the magnetic junction 110. Thus,
the materials and configuration of the free layer 112 in the
magnetic junction 110H is analogous to that in the magnetic
junction 110. For example, the free layer 112 may be a SAF or other
multilayer. The magnetic junction 110H may also include optional
PEL(s) having a high spin polarization. Contact, optional seed
layer(s) and optional capping layer(s) may be present but are not
shown for simplicity. Although the free layer 112 is shown as
adjoining the SO active layer 130, in other embodiments, a layer,
such as interlayer 118, may be inserted between the sides of the SO
active layer 130 and the free layer 112. Further, although shown as
completely surrounding the sides of the SO active layer 130, in
other embodiments, the free layer 112 may include an aperture or
may terminate without completely surrounding the SO active layer
130.
[0056] Thus, the magnetic junction 110A includes a free layer 112.
However, the nonmagnetic spacer layer 114 and a reference layer 116
of the magnetic junction 110 are omitted. Consequently, STT is not
used in programming the free layer 112. In some embodiments, an
external magnetic field may be used in addition to SO torque to
write to the free layer 112. In addition, the magnetic junction
110H is read using a current driven along the z-axis through the SO
active layer 130 that is insufficient to program the free layer
112.
[0057] For example, FIGS. 9A-9F depict cross-sectional views of an
exemplary embodiment of the magnetic device 100H including vertical
magnetic junctions programmable using SO torque during writing and
reading. FIGS. 9A and 9B depict the magnetic junction 100H just
after having been programmed. FIG. 9A depicts the magnetic junction
110H after a write current Jc+ has been driven through the SO
active layer 130. Thus, the free layer 112 has been written such
that its magnetic moment 113H is stable in the orientation shown.
FIG. 9B depicts the magnetic junction 110H after write current Jc-
has been driven through the SO active layer 130. Thus, the free
layer 112 has been written such that its magnetic moment 113H' is
stable in the opposite direction.
[0058] FIGS. 9C-9F depict side views of the magnetic device 10H
during reading. The magnetic junction 110A is read using currents
having current densities J+ and J- driven along the z-axis through
the SO active layer 130. This current is insufficient to program
the free layer 112. The state of the free layer 112 is read using
the difference in resistance due to the configurations of the spins
in the SO active layer 130 and the magnetic moment of the free
layer 112. FIGS. 9C and 9D depict the magnetic device 10H when the
free layer magnetic moment circulates around the SO active layer
130 as shown (out of the plane of the page on one side of the layer
130 and into the plane of the page on the other). In FIG. 9C, the
current J+ results in spins of opposite orientation migrating to
opposite sides of the SO active layer, as shown. With the current
J+, the spins align with the magnetic moment of the free layer 112
and result in a resistance of R1+. As shown in FIG. 9D, the spins
in the SO active layer 130 are opposite to the magnetic moment of
the free layer 112. The resulting resistance is R1-. In addition,
R1->R1+. Thus, a differential measurement results in a negative
difference in resistance between J+ and J-.
[0059] FIGS. 9E and 9F depict a resistance measurement when the
free layer 112 has a magnetic moment in the opposite direction. The
current J+ results in the spins migrating within the SO active
layer 130 in the same manner as for FIG. 9C. However, in this case,
the spins are in the opposite direction as the free layer magnetic
moment and result in a resistance of R2+. For the current J-, the
spins migrate as shown in FIG. 9D. However, the spins now align
with the magnetic moment of the free layer 112 and result in a
resistance R2-. Further, R2-<R2+. Thus, a differential
resistance measurement results in a positive difference in
resistance between J+ and J-. Thus, the magnetic junction 100H may
be read and programmed using currents only through the SO active
layer 130.
[0060] Although specific magnetic devices 100, 100A, 100B, 100C,
100D, 100E, 100F, 100G and 100H and particular magnetic junctions
110, 110A, 110B, 110C, 110D, 110E, 110F, 110G and 110H have been
described herein, one of ordinary skill in the art will recognize
that one or more of the features described herein may be combined
in manners not explicitly shown.
[0061] FIG. 10 is a perspective view of an exemplary embodiment of
a memory 200A that may use one or more of the magnetic devices 100,
100A, 100B, 100C, 100D, 100E, 100F, 100G, 100H and/or other
magnetic devices including a vertical magnetic junction written
using SO torque. Only a portion of the magnetic memory 200A is
shown. For example, reading/writing column select drivers as well
as word line select driver(s) are not shown. Note that other and/or
different components may be provided.
[0062] The memory 200A includes a substrate 202, lines 201 and 203
and memory cells 210A. Each memory cell 210A includes a selection
transistor 220A, magnetic junction 212 and SO active layer 211.
Although only one magnetic junction 212 per cell is shown, in other
embodiments, additional magnetic junctions may be used. The SO
active layer 211 is analogous to the SO active layer 130 and/or
130G/line 131. The magnetic junctions 212 are analogous to the
magnetic junction(s) 110, 110A, 110B, 110C, 110D, 110E, 110F, 110G,
110H and/or another vertical magnetic junction. In addition, as can
be seen by the orientation of the magnetic junctions 212 with
respect to the substrate 202, the magnetic junctions 212 have
interfaces (not shown) that may be substantially perpendicular to
the substrate 202. The transistor 220A shown are planar
transistors. In another embodiment, another selection device might
be used. For example, an ovonic threshold selector (OTS) device
might be used. In addition, also shown are lines 201 that may be
used to drive current through the magnetic junction 212 for reading
and/or writing. However, if a free layer only magnetic junction
100H is used, the lines 201 may be omitted. Because the magnetic
memory 200A uses the magnetic junctions 212 and SO active layers
211, the magnetic memory 200A may enjoy the benefits described
above.
[0063] FIG. 11 is a perspective view of an exemplary embodiment of
a memory 200B that may use one or more of the magnetic devices 100,
100A, 100B, 100C, 100D, 100E, 100F, 100G, 100H and/or other
magnetic devices including a vertical magnetic junction written
using SO torque. Only a portion of the magnetic memory 200B is
shown. For example, reading/writing column select drivers as well
as word line select driver(s) are not shown. Note that other and/or
different components may be provided.
[0064] The memory 200B includes a substrate 202, lines 201 and 203
and memory cells 210B. Each memory cell 210B includes a selection
transistor 220B, magnetic junction 212 and SO active layer 211.
Although only one magnetic junction 212 per cell is shown, in other
embodiments, additional magnetic junctions may be used. The SO
active layer 211 is analogous to the SO active layer 130 and/or
130G/line 131. The magnetic junctions 212 are analogous to the
magnetic junction(s) 110, 110A, 110B, 110C, 110D, 110E, 110F, 110G,
110H and/or another vertical magnetic junction. In addition, as can
be seen by the orientation of the magnetic junctions 212 with
respect to the substrate 202, the magnetic junctions 212 have
interfaces (not shown) that may be substantially perpendicular to
the substrate 202. The transistor 220B shown are planar
transistors. In another embodiment, another selection device
including but not limited to an OTS selection device might be used.
Also shown are lines 201 that may be used to drive current through
the magnetic junction 212 for reading and/or writing. However, if a
free layer only magnetic junction 100H is used, the lines 201 may
be omitted.
[0065] Also shown in FIG. 11 is additional selector 230B. The
selector 230B may be an OTS selector or other analogous device.
Because the magnetic memory 200B uses the magnetic junctions 212
and SO active layers 211, the magnetic memory 200B may enjoy the
benefits described above. In addition, use of two selection devices
220B and 230B may reduce or eliminate the sneak path for current.
As such, performance may be further improved.
[0066] FIG. 12 is a perspective view of an exemplary embodiment of
a memory 200C that may use one or more of the magnetic devices 100,
100A, 100B, 100C, 100D, 100E, 100F, 100G, 100H and/or other
magnetic devices including a vertical magnetic junction written
using SO torque. Only a portion of the magnetic memory 200C is
shown. For example, reading/writing column select drivers as well
as word line select driver(s) are not shown. Note that other and/or
different components may be provided.
[0067] The memory 200C includes a substrate 202, lines 201 and 203
and memory cells 210C. Each memory cell 210C includes a selection
transistor 220C, magnetic junction 212 and SO active layer 211. An
optional second selection device 230C is also shown. Although only
one magnetic junction 212 per cell is shown, in other embodiments,
additional magnetic junctions may be used. The SO active layer 211
is analogous to the SO active layer 130 and/or 130G/line 131. The
magnetic junctions 212 are analogous to the magnetic junction(s)
110, 110A, 110B, 110C, 110D, 110E, 110F, 110G, 110H and/or another
vertical magnetic junction. In addition, as can be seen by the
orientation of the magnetic junctions 212 with respect to the
substrate 202, the magnetic junctions 212 have interfaces (not
shown) that may be substantially perpendicular to the substrate
202. Also shown are lines 201 that may be used to drive current
through the magnetic junction 212 for reading and/or writing.
However, if a free layer only magnetic junction 100H is used, the
lines 201 may be omitted. The transistor 220C shown are vertical
(three-dimensional) transistors instead of planar transistors.
[0068] Because the magnetic memory 200C uses the magnetic junctions
212 and SO active layers 211, the magnetic memory 200C may enjoy
the benefits described above. In addition, if two selection devices
220C and 230C are used, the sneak path for current may be reduced
or eliminated. As such, performance may be further improved.
Further, the magnetic memory 200C may be more scalable because of
the use of three dimensional transistors 220C. Thus, the magnetic
memory 200C may have enhanced performance.
[0069] FIG. 13 depicts an exemplary embodiment of a schematic for a
memory 300A that may use one or more of the magnetic devices 100,
100A, 100B, 100C, 100D, 100E, 100F, 100G, 100H and/or other
magnetic devices including vertical magnetic junctions programmable
using SO torque. Only a portion of the magnetic memory 300A is
shown. For example, reading/writing column select drivers as well
as word line select driver(s) are not shown. Note that other and/or
different components may be provided.
[0070] The magnetic memory 300A includes word lines 301,
Vcc/Vdd/ground/read voltage lines 303, Vcc/Vdd/ground/floating
lines 305, output lines 307 that may connect to a sense amplifier,
magnetic junctions 312, SO active layers 311, selection transistor
320 and optional additional selection device 330A. The components
311, 312, 320 and (optionally) 330A form cells 310A. For simplicity
only one cell is labeled. Each magnetic junction 312 is shown as
connected to line 307. However, if a free layer only magnetic
junction 100H is used this connection may be omitted.
[0071] Because the magnetic memory 300A uses the magnetic junctions
312 and SO active layers 311, the magnetic memory 300A may enjoy
the benefits described above. In addition, if two selection devices
320 and 330A are used, the sneak path for current may be reduced or
eliminated. As such, performance may be further improved. If the
transistor 320 is a vertical transistor such as the transistor
220C, the magnetic memory 300A may be more scalable. Thus, the
magnetic memory 300A may exhibit improved performance.
[0072] FIG. 14 depicts an exemplary embodiment of a schematic for a
memory 300B that may use one or more of the magnetic devices 100,
100A, 100B, 100C, 100D, 100E, 100F, 100G, 100H and/or other
magnetic devices including vertical magnetic junctions programmable
using SO torque. Only a portion of the magnetic memory 300B is
shown. For example, reading/writing column select drivers as well
as word line select driver(s) are not shown. Note that other and/or
different components may be provided.
[0073] The magnetic memory 300B is analogous to the magnetic memory
300A. Consequently, the magnetic memory 300B includes word lines
301, Vcc/Vdd/ground/read voltage lines 303, Vcc/Vdd/ground/floating
lines 305, output lines 307 that may connect to a sense amplifier,
magnetic junctions 312, SO active layers 311 and selection
transistor 320 that are analogous to components 301, 303, 305, 307,
312, 311 and 320, respectively. The components 311, 312, 320 and
(optionally) 332B form cells 310B. For simplicity only one cell is
labeled. Each magnetic junction 312 is shown as connected to line
307. However, if a free layer only magnetic junction 100H is used
this connection may be omitted.
[0074] Each memory cell 310B may include an optional diode 332B.
The diode 332B may be used to eliminate the sneak path. In lieu of
a diode 332B, another configuration that functions as a diode may
be used.
[0075] Because the magnetic memory 300B uses the magnetic junctions
312 and SO active layers 311, the magnetic memory 300B may enjoy
the benefits described above. In addition, if the diodes 332B are
used, the sneak path for current may be reduced or eliminated. As
such, performance may be further improved. If the transistor 320 is
a vertical transistor such as the transistor 220C, the magnetic
memory 300B may be more scalable. Thus, the magnetic memory 300B
may exhibit improved performance.
[0076] FIGS. 15-16 depict perspective views of other exemplary
embodiments of a magnetic devices 400A and 400B including multiple
vertical magnetic junctions 412 programmable using SO torque. The
magnetic junctions 412 are analogous to the magnetic junction(s)
110, 110A, 110B, 110C, 110D, 110E, 110F, 110G, 110H and/or another
vertical magnetic junction. Also shown are SO active layers 411
analogous to the SO active layers 130 and/or 130G/line 131. For
simplicity, not all SO active layers 411 are labeled in FIG. 15.
Although a particular number of magnetic junctions are shown in
each magnetic device 400A and 400B, in other embodiments, other
number(s) may be used. In the magnetic device 400B, isolation
devices 414 are shown as interleaved between the magnetic junction
412. For example, the isolation devices 414 might be vertical
transistors analogous to the transistor 220C. The magnetic devices
400A and/or 400B might be incorporated into a device utilizing the
magnetic devices 100, 100A, 100B, 100C, 100D, 100E, 100F, 100G,
100H and/or an analogous device. For example, one or more of the
magnetic memories 200A, 200B, 200C, 300A and/or 300B might use the
magnetic device 400A and/or 400B.
[0077] In some embodiments, the magnetic junctions 412 may be
individually programmed using a combination of current driven
through the SO active layers 411 (i.e. using SO torque) and a
current driven through the magnetic junction (e.g. STT torque).
Such embodiments include those in which the SO torque is collinear
with the magnetization, such as the magnetic junction 100B. For
example, a write current that is insufficient to write to the
magnetic junction 412 alone may be driven through the SO active
layer 411. Each magnetic junction 412 to be written may
simultaneously have an STT current driven through it. For example,
the STT current may be radial or simply in a particular direction
that allows the STT current to pass through the interface(s)
between the layers of the magnetic junction 412. The combination of
the currents driven in the appropriate directions writes to the
desired magnetic junctions 412. In some embodiments, an STT current
driven in one direction through the magnetic junctions 412 to be
switched aids in programming, while an STT current driven in the
opposite direction through magnetic junctions 412 not to be
switched prevents writing to such magnetic junctions from being
programmed. In other embodiments, a current is driven through the
SO active layer 411. A small STT current may be driven through the
magnetic junctions 412 desired to be written, for example to select
the final direction of magnetization after programming. In some
embodiments, the magnetic moment of the free layer of each magnetic
junction 412 may be stable radially, in a manner analogous to the
magnetic junction 100C. A current driven through the SO active
layer may destabilize the magnetic moments such that the free layer
magnetic moments circulate around the SO active layer 411. The
final direction of magnetization may be set by applying a small STT
current to the magnetic junction(s) 412 desired to be programmed.
When the currents are removed, the magnetic junctions 412 are
programmed in the desired radial direction. In another embodiment,
the magnetic moment of the free layer of each magnetic junction 412
is stable axially (along the axis of the cylinder shown in FIGS. 15
and 16) in a manner analogous to the magnetic junction 100A. In
such an embodiment, a current driven through the SO active layer
may still destabilize the magnetic moments such that the free layer
magnetic moments circulate around the SO active layer 411. The
final direction of magnetization may be set by applying a small STT
current to the magnetic junction(s) 412 desired to be programmed.
This STT torque has an axial direction due to the magnetic moment
of the reference layer. When the currents are removed, the magnetic
junctions 412 are programmed in the desired axial direction.
[0078] FIG. 17 depicts an exemplary embodiment of a method 500 for
fabricating a magnetic device programmable using SO torque and
including vertical magnetic junctions. For simplicity, some steps
may be omitted, performed in another order, include substeps and/or
combined. Further, the method 500 may start after other steps in
forming a magnetic memory have been performed. For simplicity, the
method 500 is described in the context of the magnetic device 100.
However, other magnetic devices, including but not limited to the
magnetic devices 100A, 100B, 100C, 100D, 100E, 100F, 100G and/or
100H may be formed.
[0079] At least one SO active layer 130 is provided, via step 502.
Step 502 may include depositing and patterning the desired
materials for each SO active layer 130. In some embodiments, step
502 includes forming the low conductivity core 132 and the SO
active layer 130G on the core 132. Thus, a pillar may be formed in
step 502. The interlay layer 118 may optionally be provided as part
of step 502.
[0080] The magnetic junctions 110 may then be formed, via step 504.
Step 504 may include blanket depositing the layers for the free
layer 112, nonmagnetic spacer layer 114, reference layer 116 and
any additional layers desired in the magnetic junction 110.
Alternatively, the nonmagnetic spacer layer 114 and/or reference
layer 114 might be omitted. Anneal(s) and/or other processing steps
may also be performed. The magnetic junctions 110 may then be
defined. For example, a planarization step may remove the portions
of the magnetic junctions 110 connection layer 112, 114 and 116 and
the SO active layer 130 physically exposed.
[0081] Fabrication may then be completed, via step 506. For
example, isolation and/or selection devices may be formed. If
magnetic devices 400A and/or 400B are to be fabricated, then
subsequent SO active layers 130 and magnetic junctions 110 may be
formed.
[0082] Using the method 500, the magnetic devices 100, 100A, 100B,
00C, 100D, 100E, 100F, 100G, and/or analogous magnetic devices may
be fabricated. As a result, the benefits of the magnetic devices
100, 100A, 100B, 00C, 100D, 100E, 100F and/or 100G may be
achieved.
[0083] FIG. 18 depicts an exemplary embodiment of a method 510 for
programming a magnetic junction using SO torque. For simplicity,
some steps may be omitted, performed in another order, include
substeps and/or combined. Further, the method 510 may start after
other steps have been performed. For simplicity, the method 510 is
described in the context of the magnetic junction 110. However,
other magnetic junctions, including but not limited to the magnetic
junctions 110A, 110B, 110C, 110D, 110E, 110F, 110G, 110H and/or an
analogous magnetic junction may be programmed.
[0084] The desired current is driven through the SO active layer
130/line 131, via step 512. Thus, the current is driven along the
axis of the SO active layer 130/lien 131 and substantially
perpendicular to the sides. In embodiments, in which the current
through the SO torque is sufficient to program the device as
desired, then the method 510 terminates.
[0085] However, in some embodiments, multiple currents are used to
program a magnetic junction. Thus, an additional STT current may be
driven, via step 512. In some embodiments, the STT current is
driven through the magnetic junctions to be programmed. In such
embodiments, the STT current is desired to assist in programming
and/or select the final state of the free layer 112. In other
embodiments, the STT current may be driven through magnetic
junctions whether or not they are to be programmed. In such
embodiments, the direction of the STT current provided in step 514
depends upon whether the magnetic junction 110 is to be programmed.
If so, the STT current is driven in a direction that adds to the SO
torque. If not, the STT current is driven in a direction such that
the STT torque opposes the SO torque. In some embodiments, the
current through the SO active layer 130 commence at substantially
the same time as the STT current. In other embodiments, the current
through the SO active layer is started first, and the STT current
commences later. Similarly, in some embodiments, the current
through the SO active layer 130 may be terminated before the STT
current goes to zero. In other embodiments, the STT current may be
terminated before the current through the SO active layer 130. In
still other embodiments, the current through the SO active layer
130 and the STT current through the magnetic junction may be
terminated at substantially the same time. However, in most
embodiments, the current through the SO active layer 130 and the
STT current overlap in time.
[0086] Thus, the magnetic junctions 110, 110A, 110B, 110C, 110D,
110E, 110F, 110G, 110H, 212, 312 and/or 412 may be programmed. As a
result, the benefits of the magnetic device(s) 100, 100A, 100B,
100C, 100D, 100E, 100F, 100G, 100H, 200, 200B, 200C, 300A, 300B,
400A and/or 400B may be achieved.
[0087] A method and system for providing and using 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.
* * * * *