MEMORY DEVICE AND METHOD OF FORMING THE SAME
A memory device may be provided, including a first planar electrode, a second planar electrode, and a switching element arranged between the first planar electrode and the second planar electrode to where a first side of the switching element is arranged over the first planar electrode and where a second side of the switching element is arranged under the second planar electrode. The switching element is thicker at the first side than the second side, and the switching element is configured to provide a conductive filament formation region.
The present disclosure relates generally to a memory device and a method of forming a memory device.
BACKGROUNDResistive random access memory (ReRAM) is a type of non-volatile memories (NVM), which has a simple structure, promising scalability, fast operation and low operation voltage.
ReRAM typically has a metal-insulator-metal structure in which the insulator refers to a resistive-change material capable of providing variable resistances. The resistance change results from the formation or rupture of a conductive filament path between the two metal electrodes upon application of a voltage bias.
When the resistive layer 106 is insulating, the resistive layer has a high resistance and the ReRAM 100 is in a high resistance state. To set the ReRAM 100, a sufficiently high voltage bias (a set voltage Vset) is applied between the two electrodes 102, 104, and conducting filaments 108 may be formed between the top and bottom electrodes to make the resistive layer 106 conductive. As shown in
According to various non-limiting embodiments, there may be provided a memory device. The memory device may include a first planar electrode; a second planar electrode; and a switching element arranged between the first planar electrode and the second planar electrode to where a first side of the switching element is arranged over the first planar electrode and where a second side of the switching element is arranged under the second planar electrode. The switching element is thicker at the first side than the second side, and the switching element is configured to provide a conductive filament formation region.
According to various non-limiting embodiments, there may be provided a method of forming a memory device. The method may include providing a first planar electrode; providing a switching element over the first planar electrode; and providing a second planar electrode over the switching element. The switching element is arranged to where a first side of the switching element is arranged over the first planar electrode and where a second side of the switching element is arranged under the second planar electrode. The switching element is thicker at the first side than the second side, and the switching element is configured to provide a conductive filament formation region.
In the drawings, like reference characters generally refer to the same parts throughout the different views. Also, the drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention. Embodiments of the invention will now be illustrated for the sake of example only with reference to the following drawings, in which:
Aspects of the present invention and certain features, advantages, and details thereof, are explained more fully below with reference to the non-limiting examples illustrated in the accompanying drawings. Descriptions of well-known materials, fabrication tools, processing techniques, etc., are omitted so as not to unnecessarily obscure the invention in detail. It should be understood, however, that the detailed description and the specific examples, while indicating aspects of the invention, are given by way of illustration only, and are not by way of limitation. Various substitutions, modifications, additions, and/or arrangements, within the spirit and/or scope of the underlying inventive concepts will be apparent to those skilled in the art from this disclosure.
Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about,” is not limited to the precise value specified. In some instances, the approximating language may correspond to the precision of an instrument for measuring the value.
The terminology used herein is for the purpose of describing particular examples only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprise” (and any form of comprise, such as “comprises” and “comprising”), “have” (and any form of have, such as “has” and “having”), “include (and any form of include, such as “includes” and “including”), and “contain” (and any form of contain, such as “contains” and “containing”) are open-ended linking verbs. As a result, a method or device that “comprises,” “has,” “includes” or “contains” one or more steps or elements possesses those one or more steps or elements, but is not limited to possessing only those one or more steps or elements. Likewise, a step of a method or an element of a device that “comprises,” “has,” “includes” or “contains” one or more features possesses those one or more features, but is not limited to possessing only those one or more features. Furthermore, a device or structure that is configured in a certain way is configured in at least that way, but may also be configured in ways that are not listed.
It should be understood that the terms “on”, “over”, “top”, “bottom”, “down”, “side”, “back”, “left”, “right”, “front”, “lateral”, “side”, “up”, “down” etc., when used in the following description are used for convenience and to aid understanding of relative positions or directions, and not intended to limit the orientation of any device, or structure or any part of any device or structure. In addition, the singular terms “a”, “an”, and “the” include plural references unless context clearly indicates otherwise. Similarly, the word “or” is intended to include “and” unless the context clearly indicates otherwise.
The non-limiting embodiments described below in context of the devices are analogously valid for the respective methods, and vice versa. Furthermore, it will be understood that the embodiments described below may be combined; for example, a part of one embodiment may be combined with a part of another embodiment.
It will be understood that any property described herein for a specific device may also hold for any device described herein. It will be understood that any property described herein for a specific method may also hold for any method described herein. Furthermore, it will be understood that for any device or method described herein, not necessarily all the components or steps described must be enclosed in the device or method, but only some (but not all) components or steps may be enclosed.
Various non-limiting embodiments relate to a memory device, for example, a non-volatile memory device, such as a resistive random access memory device (ReRAM).
As shown in
According to various non-limiting embodiments, the memory device 200 provides the switching element 210 thicker at the first side 212 than the second side 214, and accordingly the conductive filament formation region provided therein is also thicker at the first side 212 than the second side 214. In this manner, the conductive filament formation region may be restricted or confined to a narrower/thinner area at the second side 214, which enables generation of more robust conductive filaments. Compared to conventional memory devices with set voltage (Vset) variation issues due to randomly generated filaments, the memory device 200 of various non-limiting embodiments generates more robust conductive filaments in a controlled manner and thus reduces the set voltage (Vset) variation of the memory device 200. Hence, improved switching performance can be achieved by the memory device 200 of various non-limiting embodiments.
In this context, the term “thicker” may refer to a larger dimension in width or diameter of the switching element 210 at the first side 212. In other words, the switching element 210 may be wider at the first side 212 than the second side 214. In various non-limiting embodiments, the switching element 210 may be tapered from the first side 212 to the second side 214. In a non-limiting example, an angle between the side wall and the bottom surface of the switching element 210 may be in a range from about 60° to about 80°. In various non-limiting embodiments, the switching element 210 may have a width or diameter in a range from about 70 nm to about 90 nm at the first side 212, a width or diameter in a range from about 20 nm to about 40 nm at the second side 214, and a height in a range from about 100 nm to about 120 nm.
According to various non-limiting embodiments, the switching element 210 may have a triangular or trapezoidal cross-section.
In various non-limiting embodiments, the switching element 210 may have a shape selected from the group including a cone, a truncated cone, a pyramid, a truncated pyramid, or a wedge. In various non-limiting embodiments, the switching element 210 may have any other suitable shape which is thicker at the first side 212 than the second side 214.
In various non-limiting embodiments, the switching element 210 may include a material configured to provide variable resistances upon application of a voltage bias. In various non-limiting embodiments, the switching element 210 may include a binary oxide material, examples of which may include but are not limited to silicon oxide, magnesium oxide, aluminium oxide, chromium oxide, manganese oxide, iron oxide, cobalt oxide, zinc oxide, germanium oxide, titanium oxide, nickel oxide, copper oxide, yttrium oxide, zirconium oxide, niobium oxide, molybdenum oxide, tin oxide, lanthanum oxide, hafnium oxide, tantalum oxide, tungsten oxide, cerium oxide, gadolinium oxide, ytterbium oxide, lutetium oxide, combinations thereof, or any other suitable materials.
According to various non-limiting embodiments, the first planar electrode 202 and the second planar electrode 204 may have a substantially planar or flat shape, for example, in the form of a plate. In various non-limiting embodiments, the first planar electrode 202 and the second planar electrode 204 may include an electrically conductive material, such as a metallic material. Examples of the material in the first planar electrode 202 and the second planar electrode 204 may include but are not limited to aluminium, titanium, tungsten, ruthenium, nickel, copper, silver, iridium, platinum, gold, combinations thereof, or any other suitable materials.
According to various non-limiting embodiments, the memory device 200 may further include a layer (not shown in
The memory device 200 may further include a dielectric layer (not shown in
According to various non-limiting embodiments, the memory device 200 may further include a component (not shown in
In various non-limiting embodiments, the component may include a nanopillar. The nanopillar may have a first end in contact with the switching element 210, and a second end in contact with the second planar electrode 204. In various non-limiting embodiments, the second end of the nanopillar may include a sharp tip or a tapered tip in contact with the second planar electrode 204.
In various non-limiting embodiments, the component may include a film embedded with nanoparticles. In various non-limiting embodiments, the film may include an oxide film, and the nanoparticles may include metal nanoparticles. In various non-limiting embodiments, the metal nanoparticles may include nanocrystals. Examples of the material in the nanocrystals may include but are not limited to aluminium, titanium, tungsten, ruthenium, nickel, copper, silver, iridium, platinum, gold, combinations thereof, or any other suitable materials. In various non-limiting embodiments, the nanoparticles may have a diameter in a range from about 2 nm to about 10 nm.
According to various non-limiting embodiments, the switching element 210 may include a plurality of nanowires (not shown in
Each nanowire of the plurality of nanowires may include a first end and a second end, wherein the first ends of the plurality of nanowires are arranged near the first planar electrode 202, and the second ends of the plurality of nanowires are arranged near the second planar electrode 204. In various non-limiting embodiments, an area enclosed by the first ends of the plurality of nanowires, e.g. at the first side 212 of the switching element 210, is substantially thicker than an area enclosed by the second ends of the plurality of nanowires, e.g. at the second side 214 of the switching element 210. In various non-limiting embodiments, the plurality of nanowires may be agglomerated at the second ends 214. In various non-limiting embodiments, each of the plurality of nanowires may have a length in a range from about 500 nm to about 1000 nm, and a diameter in a range from about 5 nm to about 20 nm.
According to various non-limiting embodiments, the memory device 200 may be a non-volatile memory device, for example, a resistive random access memory device (ReRAM) wherein the switching element 210 may include a binary oxide material as described in various non-limiting embodiments above. In various non-limiting embodiments, the memory device 200 may be any other resistive-based non-volatile memory, e.g. a phase-change random access memory device (PCRAM), where the resistances of the switching element 210 may be switched between different states by applying appropriate voltage bias. In various non-limiting embodiments wherein the memory device 200 is a PCRAM, the switching element 210 may include a phase-change material which may be switched between a crystalline phase (in which the phase-change material may have a lower resistance) and an amorphous phase (in which the phase-change material may have a higher resistance) by joule heating. Examples of the phase-change material may include but are not limited to germanium-antimony-tellurium alloys, e.g. germanium telluride (GeTe), germanium antimony telluride (GeSbTe).
Similar to the memory device 200, the memory device 300 includes the first planar electrode 202; the second planar electrode 204; and the switching element 210 arranged between the first planar electrode 202 and the second planar electrode 204 to where the first side 212 of the switching element 210 is arranged over the first planar electrode 202 and where the second side 214 of the switching element 210 is arranged under the second planar electrode 204. The switching element 210 is thicker at the first side 212 than the second side 214, and the switching element 210 is configured to provide a conductive filament formation region.
As shown in
In various non-limiting embodiments, the layer 306 may include a diffusion barrier layer, or an adhesion layer, or a combination of a diffusion barrier layer and an adhesion layer. Examples of the material of the layer 306 may include but are not limited to titanium, titanium nitride, tantalum, tantalum nitride, combinations thereof, or any other suitable materials. In various non-limiting embodiments, the thickness of the layer 306 may be less than 5 nm.
As shown in
Similar to the memory device 300, the memory device 400 may also include the layer 306 at least partially lining the switching element 210. In the non-limiting embodiments shown in
As shown in
In various non-limiting embodiments, the component 420 may include a nanopillar 420. The nanopillar 420 may have a pillar shaped body at the bottom in contact with the switching element 210, and a tapered pointy end on top in contact with the second planar electrode 204. The nanopillar 420 may have a width or diameter on the order of nanometers. In various non-limiting embodiments, the nanopillar 420 may have a height in a range from about 40 nm to about 50 nm, and a radius of curvature in a range from about 5 nm to about 20 nm. In a non-limiting embodiment, the radius of curvature of the nanopillar 420 may be about 20 nm at the bottom of the pillar shaped body in contact with the switching element 210, and the radius of curvature of the nanopillar 420 may be about 5 nm at the top of the pointy end in contact with the second planar electrode 204. When the pointy end of the nanopillar 420 is sufficiently sharp or thin, e.g. around 5 nm in the radius of curvature, the pointy end may be referred to as a sharp end or a sharp tip. In various non-limiting embodiments, the nanopillar 420 may be formed of metal, which may provide better conductivity for the conductive filaments formed therein. In various non-limiting embodiments, the nanopillar 420 may be formed of other suitable conductive materials.
According to various non-limiting embodiments, the nanopillar 420 is provided to further concentrate the conductive filaments at the second side 214 of the switching element 210, thereby generating more robust conductive filaments.
In the non-limiting embodiments shown in
Similar to the memory device 400 of
In the non-limiting embodiments shown in
According to various non-limiting embodiments, the nanoparticles 524 are provided to further concentrate the conductive filaments at the second side 214 (e.g. the vertex region) of the switching element 210, thereby generating more robust conductive filaments.
Similar to the memory device 400 of
In the non-limiting embodiments shown in
Each nanowire 611 of the plurality of nanowires 611 may include a first end 612 and a second end 614, wherein the first ends 612 of the plurality of nanowires 611 are arranged near the first planar electrode 202 and the second ends 614 of the plurality of nanowires 611 are arranged near the second planar electrode 204. In various non-limiting embodiments, an area enclosed by the first ends 612 of the plurality of nanowires 611, e.g. at the first side 212 of the switching element 210, is substantially thicker than an area enclosed by the second ends 612 of the plurality of nanowires 611, e.g. at the second side 214 of the switching element 210.
In various non-limiting embodiments, the plurality of nanowires 611 may be formed of metal, such as but not limited to copper, silver, gold, alloys thereof, combinations thereof, or any other suitable material. The nanowires 611 may have a length in a range from about 500 nm to about 1000 nm and a diameter in a range from about 5 nm to about 20 nm.
Similar to the memory device 400 of
Although the non-limiting embodiments of
By providing the switching element 210 including the nanowires 611, the conductive filament formation regions may be confined along the nanowires 611, such that the conductive filaments may be guided along the nanowires 611 and concentrated at the second ends 614 of the nanowires 611. Hence, the memory device 600 forms more robust filaments and provides improved switching performance.
According to various non-limiting embodiments described above, the memory devices 200, 300, 400, 500, 600 provide a smaller effective area for conductive filament formation. Due to spatial confinement, more robust conductive filaments may be formed. The movement of the conductive filaments may be restricted by concentrating them at the second side 214 (e.g. the tip or vertex area) of the switching element 210. Therefore, the memory devices 200, 300, 400, 500, 600 of various non-limiting embodiments achieve better switching behaviour and reduce Vset variation especially at the vertex area of the switching element 210.
As shown in
In the non-limiting embodiments shown in
In the following, a method of forming the memory devices 200, 300, 400, 500, 600 according to various non-limiting embodiments will be described.
At 802, a first planar electrode may be provided.
At 804, a switching element may be provided over the first planar electrode.
At 806, a second planar electrode may be provided over the switching element. The switching element may be arranged to where a first side of the switching element is arranged over the first planar electrode and where a second side of the switching element is arranged under the second planar electrode. The switching element is thicker at the first side than the second side, wherein the switching element is configured to provide a conductive filament formation region.
According to various non-limiting embodiments, the first planar electrode and the second planar electrode may be provided with a substantially planar or flat shape, for example, in the form of a plate. In various non-limiting embodiments, the first planar electrode and the second planar electrode may include a metallic material, examples of which may include but are not limited to aluminium, titanium, tungsten, ruthenium, nickel, copper, silver, iridium, platinum, gold, combinations thereof, or any other suitable materials.
According to various non-limiting embodiments, providing the switching element at 804 may include forming a switching layer over the first planar electrode, and etching or milling the switching layer to form the switching element. The switching element may have a triangular or trapezoidal cross-section.
In various non-limiting embodiments, the switching layer may be formed using a sputtering deposition method, or other suitable processes. The switching layer may include a material configured to provide variable resistances upon application of a voltage bias. In various non-limiting embodiments, the switching layer may include a binary oxide material, examples of which may include but are not limited to silicon oxide, magnesium oxide, aluminium oxide, chromium oxide, manganese oxide, iron oxide, cobalt oxide, zinc oxide, germanium oxide, titanium oxide, nickel oxide, copper oxide, yttrium oxide, zirconium oxide, niobium oxide, molybdenum oxide, tin oxide, lanthanum oxide, hafnium oxide, tantalum oxide, tungsten oxide, cerium oxide, gadolinium oxide, ytterbium oxide, lutetium oxide, combinations thereof, or any other suitable materials. In various non-limiting embodiments, the switching layer may include a phase-change material, examples of which may include but are not limited to germanium-antimony-tellurium alloys, e.g. germanium telluride (GeTe), germanium antimony telluride (GeSbTe).
In various non-limiting embodiments, the switching layer may be etched using atomic layer etching (ALE), or reactive ion etching (RIE), or any other suitable etching processes. In various non-limiting embodiments, the switching layer may be milled using focused ion beam (FIB) milling, or any other suitable milling processes.
According to various non-limiting embodiments, the method may include forming a layer at least partially lining the switching element. In various embodiments, the layer may be formed using a sputtering deposition method, or any other suitable processes. The layer may include a diffusion barrier layer, or an adhesion layer, or a combination of a diffusion barrier layer and an adhesion layer. Examples of the material of the layer may include but are not limited to titanium, titanium nitride, tantalum, tantalum nitride, combinations thereof, or any other suitable materials.
According to various non-limiting embodiments, the method may include forming a dielectric layer over the first planar electrode and the switching element, wherein the dielectric layer is arranged around the switching element. The dielectric layer may include a dielectric material, examples of which may include but are not limited to silicon oxide, silicon nitride, combinations thereof , or any other suitable materials. In various non-limiting embodiments, the dielectric layer may be formed using chemical vapor deposition or any other suitable deposition processes.
According to various non-limiting embodiments, the method may further include forming a component on the switching element; and forming the second planar electrode on the component. The component is in electrical communication with the second planar electrode.
In various non-limiting embodiments, forming the component may include forming a metal layer on the switching element, and milling the metal layer to form the component. The component may include a nanopillar. In various non-limiting embodiments, the nanopillar may have a first end in contact with the switching element, and a second end in contact with the second planar electrode. In various non-limiting embodiments, the second end of the nanopillar may include a sharp tip or a tapered tip in contact with the second planar electrode. In various non-limiting embodiments, the nanopillars may be formed using the FIB milling method, wherein the milling and polishing time may be controlled and optimized to form a sharp or tapered tip at the second end of the nanopillar.
In various non-limiting embodiments, forming the component may include forming a film embedded with nanoparticles. In various non-limiting embodiments, the film may include an oxide film, and the nanoparticles may include metal nanoparticles. In various non-limiting embodiments, an oxide film with metal dopants may be deposited through radio frequency (RF) sputtering, and annealed at an elevated temperature for partial crystallization to form the nanoparticles, e.g., nanocrystals. The size of nanocrystals may be in a range from about 2 nm to about 10 nm, depending on the material selection for the nanocrystals. In various non-limiting embodiments, nanocrystals may be regularly or evenly arranged in the film, wherein the regular structural arrangement may be achieved by a self-assembly method through external forces (such as a magnetic or electric field).
According to various non-limiting embodiments, providing the switching element may include forming a plurality of nanowires extending from the first planar electrode toward the second planar electrode. In various non-limiting embodiments, each nanowire of the plurality of nanowires may include a first end and a second end, wherein the first ends of the plurality of nanowires are arranged near the first planar electrode and the second ends of the plurality of nanowires are arranged near the second planar electrode. In various non-limiting embodiments, an area enclosed by the first ends of the plurality of nanowires, e.g. at the first side of the switching element, is substantially thicker than an area enclosed by the second ends of the plurality of nanowires, e.g. at the second side of the switching element. In various non-limiting embodiments, the plurality of nanowires may be agglomerated at the second ends. In various non-limiting embodiments, the plurality of nanowires may be formed using a porous anodized alumina oxide (AAO) template.
Various non-limiting embodiments of the method of forming the memory device will be described in more detail below.
In the non-limiting embodiments of
In
In
In
In various non-limiting embodiments, the switching element 210 may be formed by atomic layer etching (ALE), which is able to remove targeted materials selectively at the atomic scale and does not cause damage to other parts of the structure. In a non-limiting example, the switching element 210 with a triangular shape and a minimum size of about 20 nm at the vertex area 214 may be formed by ALE. In alternative non-limiting embodiments, the switching element 210 may be formed by reactive ion etching (RIE), or any other suitable etching method.
In various non-limiting embodiments, the layer 306 may also be etched such that only a portion of the layer 306 under the bottom surface of the switching element 210 is retained.
In
In
In
The non-limiting embodiments described with reference to
In the non-limiting embodiments of
In
In
In
In
In various non-limiting embodiments, the metal layer 1026 and the metal oxide layer 924 may be milled to form the switching element 210 and the component 420, for example, using FIB milling. The milling process may also be used to form the switching element 210 of the memory devices 200, 300, 500.
In various non-limiting embodiments, the component 420 may include a nanopillar 420. The nanopillar 420 may have a pillar shaped body at the bottom in contact with the switching element 210, and a tapered pointy end on top. The nanopillar 420 may have a width or diameter on the order of nanometers. In various non-limiting embodiments, the nanopillar 420 may have a height in a range from about 40 nm to about 50 nm, and a radius of curvature in a range from about 5 nm to about 20 nm. In a non-limiting embodiment, the radius of curvature of the nanopillar 420 may be about 20 nm at the bottom of the pillar shaped body in contact with the switching element 210, and the radius of curvature of the nanopillar 420 may be about 5 nm at the top of the pointy end in contact with the second planar electrode 204. When the pointy end of the nanopillar 420 is sufficiently sharp or thin compared to the bottom body, the pointy end may be referred to as a sharp end or a sharp tip.
In various non-limiting embodiments, milling and polishing time of the FIB milling process may be optimized, so as to form the nanopillar 420 with a sharp tip at the vertex area. The radius of curvature at the tip of the nanopillar 420 may be substantially smaller than that at the pillar shaped bottom body of the nanopillar 420, such that the tip of the nanopillar 420 is a sharp tip. In a non-limiting example, the radius of curvature at the tip of the nanopillar 420 may be about 5 nm, and the radius of curvature at the bottom body of the nanopillar 420 may be about 20 nm. In various non-limiting embodiments, longer milling time and polishing time may produce nanopillars with sharper tips, and therefore with smaller radius of curvature at the tip compared to the body. In a non-limiting example, the milling time of about 140 s and the polishing time of about 80 s may be used as the optimized time, at which the nanopillar may be formed in a cone shape with a sharp tip at the vertex.
In
In
According to various non-limiting embodiments, the component 420 is in electrical communication with the second planar electrode 204, and is provided to further concentrate the conductive filaments at the tip area of the switching element 210, thereby generating more robust conductive filaments.
In the non-limiting embodiments of
In
In
In various non-limiting embodiments, the size (e.g., the diameter or width) of the nanocrystals 524 may be in a range from about 2 nm to about 10 nm, depending on the material selection for the nanocrystals 524. In various non-limiting embodiments, the nanocrystals 524 may have a substantially spherical shape. In various non-limiting embodiments, the nanocrystals 524 may be regularly arranged in the film 522, wherein the regular structural arrangement may be achieved by a self-assembly method through external forces (such as a magnetic or electric field).
In
According to various non-limiting embodiments of
In the non-limiting embodiments of
In
A metal layer 1202 may be formed on the first planar electrode 202. In various non-limiting embodiments, the metal layer 1202 may be deposited by e-beam evaporation or physical vapor deposition. In a non-limiting example, the metal layer 1202 may include aluminium (Al).
In various non-limiting embodiments (not shown in
In
In
In
Due to the gradual removal of AAOs 1204 and a high aspect ratio of the nanowires 1208, the tip of the nanowires 1208 may tend to agglomerate and eventually form a conical bundle of nanowires 611 as shown in
In
In the non-limiting embodiments shown in
In
According to various non-limiting embodiments of
According to various non-limiting embodiments described above, the memory devices 200, 300, 400, 500, 600 with better switching behavior and reduced Vset variation are provided, by restricting the path or region of the conductive filaments at the tip area of the switching element 210. The simple fabrication according to various non-limiting embodiments of
The following examples pertain to further embodiments.
Example 1 may be a memory device including: a first planar electrode; a second planar electrode; and a switching element arranged between the first planar electrode and the second planar electrode to where a first side of the switching element is arranged over the first planar electrode and where a second side of the switching element is arranged under the second planar electrode. The switching element may be thicker at the first side than the second side, and the switching element may be configured to provide a conductive filament formation region.
In Example 2, the subject matter of Example 1 may optionally include that the the switching element has a triangular or trapezoidal cross-section.
In Example 3, the subject matter of Example 1 or Example 2 may optionally include that the memory device may further include a layer at least partially lining the switching element.
In Example 4, the subject matter of any one of Examples 1 to 3 may optionally include that the memory device may further include a dielectric layer arranged between the first planar electrode and the second planar electrode, wherein the dielectric layer is arranged around the switching element.
In Example 5, the subject matter of any one of Examples 1 to 4 may optionally include that the memory device may further include a component arranged between the switching element and the second planar electrode, wherein the component is in electrical communication with the second planar electrode.
In Example 6, the subject matter of Example 5 may optionally include that the component may include a nanopillar.
In Example 7, the subject matter of Example 5 may optionally include that the component may include a film embedded with nanoparticles.
In Example 8, the subject matter of any one of Examples 1 to 4 may optionally include that the switching element may include a plurality of nanowires extending from the first planar electrode toward the second planar electrode.
In Example 9, the subject matter of Example 8 may optionally include that each nanowire of the plurality of nanowires may include a first end and a second end, wherein the first ends of the plurality of nanowires are arranged near the first planar electrode and the second ends of the plurality of nanowires are arranged near the second planar electrode
In Example 10, the subject matter of Example 9 may optionally include that an area enclosed by the first ends of the plurality of nanowires is substantially thicker than an area enclosed by the second ends of the plurality of nanowires.
In Example 11, the subject matter of any one of Examples 1 to 10 may optionally include that the memory device is a resistive random access memory device or a phase-change random access memory device.
Example 12 may be a method including: providing a first planar electrode; providing a switching element over the first planar electrode; and providing a second planar electrode over the switching element. The switching element is arranged to where a first side of the switching element is arranged over the first planar electrode and where a second side of the switching element is arranged under the second planar electrode. The switching element is thicker at the first side than the second side, and the switching element is configured to provide a conductive filament formation region.
In Example 13, the subject matter of Example 12 may optionally include that: providing the switching element may include forming a switching layer over the first planar electrode; etching or milling the switching layer to form the switching element. The switching element may have a triangular or trapezoidal cross-section.
In Example 14, the subject matter of Example 12 or Example 13 may optionally include that the method further includes forming a layer at least partially lining the switching element.
In Example 15, the subject matter of any one of Examples 12 to 14 may optionally include that the method further includes forming a dielectric layer over the first planar electrode and the switching element, wherein the dielectric layer is arranged around the switching element.
In Example 16, the subject matter of any one of Examples 12 to 15 may optionally include that the method further includes forming a component on the switching element; and forming the second planar electrode on the component. The component is in electrical communication with the second planar electrode.
In Example 17, the subject matter of Example 16 may optionally include that forming the component may include forming a metal layer on the switching element; and milling the metal layer to form the component. The component may include a nanopillar.
In Example 18, the subject matter of Example 16 may optionally include that forming the component may include forming a film embedded with nanoparticles.
In Example 19, the subject matter of any one of Examples 12, 14 to 15 may optionally include that providing the switching element may include forming a plurality of nanowires extending from the first planar electrode toward the second planar electrode.
In Example 20, the subject matter of Example 19 may optionally include that each nanowire of the plurality of nanowires includes a first end and a second end, wherein the first ends of the plurality of nanowires are arranged near the first planar electrode and the second ends of the plurality of nanowires are arranged near the second planar electrode.
The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The foregoing embodiments, therefore, are to be considered in all respects illustrative rather than limiting the invention described herein. Scope of the invention is thus indicated by the appended claims, rather than by the foregoing description, and all changes that come within the meaning and range of equivalency of the claims are intended to be embraced therein.
Claims
1. A memory device, comprising:
- a first planar electrode;
- a second planar electrode; and
- a switching element arranged between the first planar electrode and the second planar electrode to where a first side of the switching element is arranged over the first planar electrode and where a second side of the switching element is arranged under the second planar electrode;
- wherein the switching element is thicker at the first side than the second side; wherein the switching element is configured to provide a conductive filament formation region.
2. The memory device of claim 1, wherein the switching element has a triangular or trapezoidal cross-section.
3. The memory device of claim 1, further comprising:
- a layer at least partially lining the switching element.
4. The memory device of claim 1, further comprising:
- a dielectric layer arranged between the first planar electrode and the second planar electrode, wherein the dielectric layer is arranged around the switching element.
5. The memory device of claim 1, further comprising:
- a component arranged between the switching element and the second planar electrode; wherein the component is in electrical communication with the second planar electrode.
6. The memory device of claim 5, wherein the component comprises a nanopillar.
7. The memory device of claim 5, wherein:
- the component comprises a film embedded with nanoparticles.
8. The memory device of claim 1, wherein the switching element comprises a plurality of nanowires extending from the first planar electrode toward the second planar electrode.
9. The memory device of claim 8, wherein each nanowire of the plurality of nanowires comprises a first end and a second end, wherein the first ends of the plurality of nanowires are arranged near the first planar electrode and the second ends of the plurality of nanowires are arranged near the second planar electrode.
10. The memory device of claim 9, wherein an area enclosed by the first ends of the plurality of nanowires is substantially thicker than an area enclosed by the second ends of the plurality of nanowires.
11. The memory device of claim 1, wherein the memory device is a resistive random access memory device or a phase-change random access memory device.
12. A method of forming a memory device, the method comprising:
- providing a first planar electrode;
- providing a switching element over the first planar electrode; and
- providing a second planar electrode over the switching element;
- wherein the switching element is arranged to where a first side of the switching element is arranged over the first planar electrode and where a second side of the switching element is arranged under the second planar electrode; wherein the switching element is thicker at the first side than the second side; wherein the switching element is configured to provide a conductive filament formation region.
13. The method of claim 12, wherein providing the switching element comprises:
- forming a switching layer over the first planar electrode; and
- etching or milling the switching layer to form the switching element, wherein the switching element has a triangular or trapezoidal cross-section.
14. The method of claim 12, further comprising:
- forming a layer at least partially lining the switching element.
15. The method of claim 12, further comprising:
- forming a dielectric layer over the first planar electrode and the switching element, wherein the dielectric layer is arranged around the switching element.
16. The method of claim 12, further comprising:
- forming a component on the switching element; and
- forming the second planar electrode on the component, wherein the component is in electrical communication with the second planar electrode.
17. The method of claim 16, wherein forming the component comprises:
- forming a metal layer on the switching element; and
- milling the metal layer to form the component, wherein the component comprises a nanopillar.
18. The method of claim 16, wherein forming the component comprises:
- forming a film embedded with nanoparticles.
19. The method of claim 12, wherein providing the switching element comprises:
- forming a plurality of nanowires extending from the first planar electrode toward the second planar electrode.
20. The method of claim 19, wherein each nanowire of the plurality of nanowires comprises a first end and a second end, wherein the first ends of the plurality of nanowires are arranged near the first planar electrode and the second ends of the plurality of nanowires are arranged near the second planar electrode.
Type: Application
Filed: Aug 23, 2019
Publication Date: Feb 25, 2021
Inventors: Ju Dy LIM (Singapore), Mei Zhen NG (Singapore), Kazutaka YAMANE (Singapore), Chim Seng SEET (Singapore)
Application Number: 16/548,854