# Patent

## Title
Methods for fabricating resistive memory device switching material using ion implantation

## Abstract

A memory device comprising a doped conductive polycrystalline layer having an electrically resistive portion, is described herein. By way of example, ion implantation to a subset of the conductive polycrystalline layer can degrade and modify the polycrystalline layer, forming the electrically resistive portion. The electrically resistive portion can include resistive switching properties facilitating digital information storage. Parametric control of the ion implantation can facilitate control over corresponding resistive switching properties of the resistive portion. For example, a projected range or depth of the ion implantation can be controlled, allowing for preferential placement of atoms in the resistive portion, and fine-tuning of a forming voltage of the memory device. As another example, dose and number of atoms implanted, type of atoms or ions that are implanted, the conductive polycrystalline material used, and so forth, can facilitate control over switching characteristics of the memory device.

## Background
REFERENCE TO RELATED APPLICATIONS
The present application is a non-provisional of and claims the benefit of U.S. Provisional Patent Application Ser. No. 61/789,888 entitled “METHOD TO CREATE/MODIFY THE SWITCHING MATERIAL OF A SILVER BASED RERAM DEVICE BY MEANS OF ION IMPLANTATION” and filed Mar. 15, 2013; and is a continuation-in-part of and claims priority to U.S. patent application Ser. No. 14/034,390, filed Sep. 23, 2013 which is a continuation of U.S. patent application Ser. No. 13/585,759, filed Aug. 14, 2012, now U.S. Pat. No. 8,569,172, issued Oct. 29, 2013. These applications are incorporated herein by reference in their entirety and for all purposes.


TECHNICAL FIELD
The subject disclosure relates generally to non-volatile memory, and as one illustrative example, a non-volatile, resistive memory device.
BACKGROUND
The inventors of the present disclosure have proposed models of two-terminal memory devices that are believed by the inventors to be able to operate as viable alternatives to various memory cell technologies, such as metal-oxide semiconductor (MOS) type memory cells employed for electronic storage of digital information. Models of two-terminal memory such as resistive-switching memory devices among others, are believed by the inventors to provide some potential advantages over non-volatile FLASH MOS type transistors, including smaller die size, higher memory density, faster switching (e.g., from a relatively conductive state to a relatively non-conductive state, or vice versa), good data reliability, low manufacturing cost, and other advantages, for example.
One anticipated memory model proposed by the inventor(s) is resistive switching memory. The inventors believe resistive switching memory can hold substantial advantages over competing technologies in the semiconductor electronics industry, including, e.g., high density non-volatile storage. A resistive switching device, according to some models proposed by the inventors, has an insulator layer that is provided between a pair of electrodes and exhibits electrical pulse induced hysteretic resistance switching effects. The inventors have suggested that a filament(s) can be formed between the electrodes by a diffusion and or drift of ions that reduce or increase the resistance of the structure and remain after being induced, giving the device a non-volatile characteristic in a programmed state. The inventors are currently involved in research and development to explore additional characteristics and advantages of two-terminal memory in general.
SUMMARY
The following presents a simplified summary of the specification in order to provide a basic understanding of some aspects of the specification. This summary is not an extensive overview of the specification. It is intended to neither identify key or critical elements of the specification nor delineate the scope of any particular embodiments of the specification, or any scope of the claims. Its purpose is to present some concepts of the specification in a simplified form as a prelude to the more detailed description that is presented in this disclosure.
Various embodiments disclosed herein provide a two-terminal memory device that can comprise a first metal electrode above a first oxide layer over a semiconductor substrate. The two-terminal memory device can comprise a pillar structure that comprises contact material layer on a top surface of the first metal electrode, wherein the contact material layer is conductive. The pillar structure can also comprise a switching layer on top of the contact material, wherein the switching layer comprises contact material that is ionized. The two-terminal memory device can also include second metal electrode above and in contact with a top surface of the pillar structure, wherein the second metal electrode includes an active metal layer in contact with the top surface of the switching layer of the pillar; and a conductor layer in contact with the active material.
Various embodiments provide for a method for forming or fabricating a two-terminal memory device. The method can comprise forming a bottom metal wiring layer above an oxide layer over a semiconductor substrate and forming bottom metal electrodes from the bottom metal wiring layer. The method can comprise forming an oxide layer between the bottom metal electrodes and disposing a conductive layer in contact with a top surface of the bottom metal electrodes. The method can comprise forming a plurality of pillars from the conductive layer and forming an oxide layer between the plurality of pillars, exposing a top surface of the plurality of pillars. The method can comprise implanting ions into the top surface of the plurality of pillars from the top surface of the pillars thereby amorphizing a top portion of the plurality of pillars, forming a top metal wiring layer above the top portion of the plurality of pillars and forming top metal electrodes from the top metal wiring layer. In various embodiments, the top metal wiring layer may include an active metal material, such as copper, silver, gold, aluminum, or the like, a barrier material such as tungsten, TiN or the like, and a top metal conductor layer on top of the barrier material, e.g. Al, Cu, or the like.
Various embodiments also provide for an electronic device comprising an electronic memory unit that can comprise one or more arrays of multi-state memory cells configured to store information. The multi-state memory cells can comprise a first metal electrode above a first oxide layer over a semiconductor substrate. The multi-state memory cells can comprise a pillar structure that comprises contact material layer on a top surface of the first metal electrode, wherein the contact material layer is conductive. The pillar structure can also comprise a switching layer on top of the contact material, wherein the switching layer comprises contact material that is ionized. The multi-state memory cells can also include second metal electrode above and in contact with a top surface of the pillar structure, wherein the second metal electrode includes an active metal layer in contact with the top surface of the switching layer of the pillar; and a conductor layer in contact with the active material.
The following description and the drawings set forth certain illustrative aspects of the specification. These aspects are indicative, however, of but a few of the various ways in which the principles of the specification may be employed. Other advantages and novel features of the specification will become apparent from the following detailed description of the specification when considered in conjunction with the drawings.



BRIEF DESCRIPTION OF THE DRAWINGS
Various aspects or features of this disclosure are described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. In this specification, numerous specific details are set forth in order to provide a thorough understanding of this disclosure. It should be understood, however, that certain aspects of the subject disclosure may be practiced without these specific details, or with other methods, components, materials, etc. In other instances, well-known structures and devices are shown in block diagram form to facilitate describing the subject disclosure;
FIG. 1 illustrates a schematic diagram of an example memory cell with an ion implanted resistive switching layer in accordance with various aspects described herein.
FIG. 2 illustrates a schematic diagram of an example memory cell at a step in a fabrication process in accordance with various aspects described herein.
FIG. 3 illustrates a schematic diagram of an example memory cell at a step in a fabrication process in accordance with various aspects described herein.
FIG. 4 illustrates a schematic diagram of an example memory cell at a step in a fabrication process in accordance with various aspects described herein.
FIG. 5 illustrates a schematic diagram of an example memory cell at a step in a fabrication process in accordance with various aspects described herein.
FIG. 6 illustrates a schematic diagram of an example memory cell at a step in a fabrication process in accordance with various aspects described herein.
FIG. 7 illustrates a schematic diagram of an example memory cell at a step in a fabrication process in accordance with various aspects described herein.
FIG. 8 illustrates a schematic diagram of an example memory cell at a step in a fabrication process in accordance with various aspects described herein.
FIG. 9 illustrates a schematic diagram of an example memory cell at a step in a fabrication process in accordance with various aspects described herein.
FIG. 10 illustrates a schematic diagram of an example memory cell at a step in a fabrication process in accordance with various aspects described herein.
FIG. 11 illustrates a flowchart of an example method for fabricating a two-terminal memory device according to one or more embodiments disclosed herein.
FIG. 12 depicts a block diagram of a sample operating environment for facilitating implementation of one or more aspects disclosed herein.
FIG. 13 illustrates a block diagram of an example computing environment that can be implemented in conjunction with various embodiments.



DETAILED DESCRIPTION
This disclosure relates to two-terminal memory cells employed for digital information storage. In some embodiments, the two-terminal memory cells can include a resistive technology, such as a resistive-switching two-terminal memory cells. Resistive-switching two-terminal memory cells (also referred to as resistive-switching memory cells or resistive-switching memory), as utilized herein, comprise circuit components having two conductive contacts (also referred to herein as electrodes or terminals) with an active region between the two conductive contacts. The active region of the two-terminal memory device, in the context of resistive-switching memory, exhibits a plurality of stable or semi-stable resistive states, each resistive state having a distinct electrical resistance. Moreover, respective ones of the plurality of states can be formed or activated in response to a suitable electrical signal applied at the two conductive contacts. The suitable electrical signal can be a voltage value, a current value, a voltage or current polarity, or the like, or a suitable combination thereof. An example of a resistive switching two-terminal memory device, though not exhaustive, can include a resistive random access memory (resistive memory).
Various types of resistive switching memory cells are envisioned as having various types of switching mediums, such as layered amorphous silicon (a-Si), metal oxides and non-stoichiometric silicon oxides (e.g. SiOx), as well as other materials. Resistive-switching devices can have, for example, a four-layer arrangement of first metal/switching layer/conductive silicon/second metal, which can include: second metal (e.g. Cu, Al)/doped polycrystalline silicon (e.g. doped polysilicon, doped polycrystalline silicon germanium)/resistive (amorphous silicon, intrinsic semiconductor, SiOx) switching layer/first metal (e.g. Ag, Au, Pt, Al, etc.). The resistive switching layer essentially serves as an information storage medium, and can also be referred to as a resistive switching layer (RSL), resistive switching medium (RSM), a switching medium, an inducting switching medium, or the like. The switching layer, as referred to herein, can include other materials as well, such as oxides, solid electrolyte materials, etc., and the first metal and the second metal may include additional barrier layers, adhesion layers, and the like.
Embodiments of the subject disclosure can provide a filamentary-based memory cell. One example of a filamentary-based memory cell can comprise: a p-type or n-type silicon (Si) bearing layer (e.g., p-type or n-type polysilicon, p-type or n-type SiGe, etc.), a resistive switching layer (RSL) and an active metal layer for providing filament forming ions to the RSL. The p-type or n-type Si bearing layer can include a p-type or n-type polysilicon, p-type or n-type SiGe, or the like. The RSL (which can also be referred to in the art as a resistive switching media (RSM)) can comprise, e.g., an undoped amorphous Si layer, a semiconductor layer having intrinsic characteristics, a Si sub-oxide (e.g., SiOx wherein x has a value between 0.1 and 2), metallic oxide (e.g. Zinc Oxide) and so forth. Examples of the active metal layer can include, among others: silver (Ag), gold (Au), titanium (Ti), titanium-nitride (TiN) or other suitable compounds of titanium, nickel (Ni), copper (Cu), aluminum (Al), chromium (Cr), tantalum (Ta), iron (Fe), manganese (Mn), tungsten (W), vanadium (V), cobalt (Co), platinum (Pt), and palladium (Pd). Other suitable conductive materials, as well as compounds or combinations of the foregoing or similar materials can be employed for the active metal layer in some aspects of the subject disclosure. Some details pertaining to embodiments of the subject disclosure similar to the foregoing example can be found in the following U.S. patent applications that are licensed to the assignee of the present application for patent: application Ser. No. 11/875,541 filed Oct. 19, 2007 and application Ser. No. 12/575,921 filed Oct. 8, 2009, each of which are incorporated by reference herein in their respective entireties and for all purposes.
It should be appreciated that various embodiments herein may utilize a variety of memory cell technologies, having different physical properties. For instance, different resistive-switching memory cell technologies can have different discrete programmable resistances, different associated program/erase voltages, as well as other differentiating characteristics. For instance, various embodiments of the subject disclosure can employ a bipolar switching device that exhibits a first switching response (e.g., programming to one of a set of program states) to an electrical signal of a first polarity and a second switching response (e.g., erasing to an erase state) to the electrical signal having a second polarity. The bipolar switching device is contrasted, for instance, with a unipolar device that exhibits both the first switching response (e.g., programming) and the second switching response (e.g., erasing) in response to electrical signals having the same polarity and different magnitudes.
Where no specific memory cell technology or program/erase voltage is specified for the various aspects and embodiments herein, it is intended that such aspects and embodiments incorporate any suitable memory cell technology and be operated by program/erase voltages appropriate to that technology, as would be known by one of ordinary skill in the art or made known by way of the context provided herein. It should be appreciated further that where substituting a different memory cell technology would require circuit modifications that would be known to one of ordinary skill in the art, or changes to operating signal levels that would be known to one of such skill, embodiments comprising the substituted memory cell technology(ies) or signal level changes are considered within the scope of the subject disclosure.
The inventor(s) of the present application are of the opinion that two-terminal memory devices, such as resistive switching memory devices, have various advantages in the field of electronic memory. For instance, resistive-switching memory technology can generally be small, typically consuming silicon area on the order of 4F2 per adjacent resistive-switching device where F stands for the minimum feature size of a technology node (e.g., a memory cell comprising two resistive-switching devices would therefore be approximately 8F2 if constructed in adjacent silicon space if on the order of 4F2). Non-adjacent resistive-switching devices, e.g., stacked above or below each other, can consume as little as 4F2 for a set of multiple non-adjacent devices. Moreover, multi-bit devices having two, three or more bits (e.g., resistance states) per memory cell can result in even greater densities in terms of bits per silicon area consumed. These advantages can lead to greater semiconductor component density and memory density, and low manufacturing costs for a given number of digital storage bits. The inventor(s) also believes that resistive-switching memory can exhibit fast programming speed and low programming current, and smaller cell sizes enabling greater component densities. Other benefits anticipated by the inventor(s) include non-volatility, having the capacity to store data without continuous application of power, and capacity to be built between metal interconnect layers, enabling resistive switching based devices to be usable for two-dimension as well as three-dimension semiconductor architectures.
The inventors of the subject application are familiar with additional non-volatile, two-terminal memory structures. For example, ferroelectric random access memory (RAM) is one example. Some others include magneto-resistive RAM, organic RAM, phase change RAM and conductive bridging RAM, and so on. Two-terminal memory technologies have differing advantages and disadvantages, and trade-offs between advantages and disadvantages are common. For instance, various subsets of these devices can have relatively fast switching times, good durability, high memory density, low cost fabrication, long life, or the like, or combinations thereof. Meanwhile, the various subsets can also be difficult to fabricate, have compatibility problems with many common CMOS fabrication processes, poor read performance, small on/off resistance ratios, small on/off resistance ratios (e.g., leading to small sensing margin) or poor thermal stability, as well as other problems. Though resistive-switching memory technology is considered by the inventors to be one of the best technologies having the most benefits and least detriments, other two-terminal memory technologies can be utilized for some of the disclosed embodiments, where suitable to one of ordinary skill in the art.
Overview
In various embodiments of the subject disclosure, a conductive polycrystalline layer (e.g. pillar structure, planar structure, and so forth, and comprised of, e.g. doped polysilicon, doped SiGe, etc.) can be implanted with material (e.g., ions, atoms that can be ionized in response to a field, or the like) that degrade and modify an upper region of the conductive polycrystalline layer. The upper region becomes a relatively insulating layer, and includes resistive switching properties. In an embodiment, the switching properties can be adjusted so that the voltage applied to the electrodes in order to induce a change in resistive state can be modified. The projected range or depth of the ion implantation can also be controlled, allowing for preferential placement of atoms in the switching material and thus fine-tuning the required forming voltage. The dose and number of atoms implanted is also controllable, allowing for significant control over concentration. The type of atoms or ions that are implanted can be based on the type of the conductive polycrystalline material used, wherein the atoms are selected in order to amorphize the polycrystalline structure.
Non-Limiting Examples of Creating or Modifying the Switching Material of a Resistive Memory Device Using Ion Implantation
Various aspects or features of this disclosure are described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. In this specification, numerous specific details are set forth in order to provide a thorough understanding of this disclosure. It should be understood, however, that certain aspects of disclosure may be practiced without these specific details, or with other methods, components, materials, etc. In other instances, well-known structures and devices are shown in block diagram form to facilitate describing the subject disclosure.
Referring now to the drawings, FIG. 1 apparatus 100 is depicted. A memory cell 100 can include a pair of electrodes with at least one electrode as a current-limiting electrode (e.g., a bottom electrode). The cell 100 can comprise a bottom electrode 101 that comprises a monotonically increasing doping concentration profile, a localized homogeneity, and uniform crystallinity. In some embodiments, an annealing process of the device 100 at the bottom electrode 101 enables the bottom electrode 101 to comprise a controlled sheet resistance, and thus, achieve an on-state current modulability (e.g., a conductive filament on-state modulation or variance) for a uniform switching behavior within a resistive switching layer.
The memory cell device 100 can operate as a resistive memory cell device, such as a multi-state memory cell device. For example, the memory cell device 100 can initially be in an Off-state (erase state) and highly resistive to current between electrodes. In addition, the cell 100 can be programmed in an On-state (program state) to form a conductive path that decreases resistivity to a desired or a programmed degree. The programming of the cell can be a result of an electrical signal such as a polar electrical signal or an electric field. For example, a positive voltage introduced at one of the electrodes can induce an electric field that forms metal ions in the switching medium and attracts the metal ions towards the negative electrode. The cell 100 can be programmed by a sufficiently large electrical signal such that the metal ions form a conductive path (i.e. filament) through the resistive switching layer 106. Further, the cell 100 can be erased by application of an opposite polarity off-state voltage (bipolar cell) or by application of a voltage larger than the program voltage (unipolar cell) by rupturing the filament formed within the resistive switching layer 106. In such conditions, the erase voltage pulls the ions towards the second electrode layer 104, for example.
The memory cell 100 can include a plurality of electrodes that can comprise a first electrode layer 102 and a second electrode layer 104, which can represent a pair of electrodes from top (bottom) to bottom (top), respectively, or metal electrodes arranged in different configurations than the present example, such as from left to right or right to left (not shown). Between these two electrodes, a resistive switching material layer 106, or a switching layer having an insulator switching medium, can reside adjacent to the second electrode layer 104 and the bottom electrode 101, for example.
The second electrode layer 104 can comprise a conductive metal (e.g., an elemental metal, an ionically bonded metal, etc.), which can be ionized (e.g., oxidized), or can produce ions at a boundary of first electrode layer 104 and resistive switching layer 106. The ionization or production of ions can be in response to a suitable electric field, application of a suitable heat (e.g., temperature), or other suitable process. The conductive ions can be capable of leaving a boundary of the second electrode layer 104 in response to a suitable stimulus (e.g., an electric field of a suitable direction and magnitude, a suitable temperature gradient, and so forth). These conductive ions, upon leaving the second electrode layer 104 and entering another entity (e.g., the resistive switching material layer 106) can tend to alter electrical characteristics of the other entity. In some embodiments, these conductive ions can serve to increase conductivity of the other entity, at least within a vicinity of the displaced ions. When the electrical signal is withdrawn, the metal ions become non-ionic metal atoms (e.g., having no net charge). In further embodiments, metal atoms can serve to decrease conductivity of the other entity, for instance by amorphizing a crystalline structure of the other entity (e.g., amorphizing some or all of a doped polysilicon conductor, among others). As one example of the latter embodiments, resistive switching layer 106 can be formed at least in part by injecting material suitable to amorphize a subset of doped semiconductor layer 108, forming an amorphous resistive switching layer 106 distinct from, and having significantly lower conductivity than, doped semiconductor layer 108.
Suitable materials for second electrode layer 104 can vary. One example is silver, also referred to herein in its periodic table form Ag as part of an active metal portion (not shown) of the second electrode layer 104. Another example can include copper (e.g., Cu), and still other examples can include compounds of silver, copper, aluminum, or the like, or a suitable combination thereof. In one or more embodiments, second electrode layer 104 can comprise one or more additional layers (e.g., some quite thin, such as 2 to 3 nanometers (nm)), such as Ti, TiN, W, or the like, adjacent to second electrode layer 104 as a barrier layer (e.g., to mitigate oxidation), an ion migration inhibitor layer, or the like. In various embodiments, second electrode layer 104 may include a metal wiring layer (e.g. Al, Cu) that is coupled to other components, e.g. memory row drivers, memory column drivers, CMOS logic, and the like.
The memory cell 100 can be placed in an On-state (a program state) by applying an electrical signal, such as a program voltage Vp to the first electrode layer 102 that is larger than a threshold (e.g., 2 ̃6V, or other like threshold). The switching material can include amorphous silicon, amorphous silicon germanium, silicon dioxide (SiO2) or a suitable derivative of silicon dioxide, silicon-on-glass (SOG), a solid electrolyte, or another suitable chalcogenide or oxide, including silicon sub-oxide, SiOx, where x is less than or equal to 2. In some embodiments, the switching material can be formed from an upper region of a p+ polycrystalline silicon or p+ silicon germanium bearing layer using an Argon, Silicon, Oxygen plasma etch, or the like. For instance, a plasma etch may use a bias power within a range of approximately 30 watts to approximately 120 watts to convert an upper region of the polysilicon or silicon germanium material into a non-conductive amorphous silicon having p-type impurities or a native silicon oxide (from a polycrystalline silicon or a silicon germanium bearing layer).
A conductive path (not shown) can be formed within the resistive switching material/medium layer 106 in response to a suitable electric signal (e.g., an electric field or voltage, a current, and so forth) applied to the device. The electric signal applied across the switching medium 106 can induce formation of metal ions and a diffusion or drift of ions (e.g., metal ions) from the second electrode layer 104 toward the first electrode layer 102, or vice versa, from the first electrode layer 101 toward the second electrode layer 104, based on a specific configuration of the illustrated materials, location of an electro deposition, or other process parameters.
In one embodiment, the bottom electrode 101 can comprise a first and a second semiconductor layer within the semiconductor layer 108, in which a top layer comprises a doped polysilicon from a one-step deposition process of an un-doped amorphous silicon and a subsequent annealing within an ambient gas, an implantation step, as described herein, or the like. The doped polysilicon (or doped polycrystalline silicon germanium) comprises dopants from a bottom layer of doped silicon material such as a p+ silicon substrate, which is heavily doped and uniformly moves dopants (e.g., Boron or the like) into the amorphous un-doped silicon layer above. Thus, in some embodiments, the semiconductor layer 108 comprises a doping concentration that monotonically increasing profile or a relatively constant increasing profile throughout at least a portion of the material, such as from the bottom layer to the top layer, as further illustrated and discussed below.
In another aspect, the bottom electrode 101 can operate to achieve a current-limiting bottom electrode (e.g. doped semiconductor layer 108). The bottom electrode 101 can be fabricated to comprise one or more of a wide range of resistances by varying the annealing time and temperature of the annealing parameters in the fabrication processes. For example, the bottom electrode 101 can comprise a converted polysilicon or poly-Si layer within a semiconductor layer 108, which resides upon or in contact with the first electrode layer 102. The semiconductor layer 108 comprising converted polysilicon can operate to control an on-state current, which depends upon the conductivity of the bottom electrode 101.
In an aspect, depending upon the annealing process parameters (e.g., an annealing time or an annealing temperature), a different resistivity and a different sheet resistance can be obtained for controlling on-state current of the resistive memory cell device. For example, a one thousand times difference or range can be fabricated and comprised by the semiconductor layer 108 based on the various annealing parameters for annealing a single layer of un-doped amorphous silicon in the bottom electrode 101. Additionally, the thickness of the bottom electrode over the device, an array or a wafer, for example, can be controlled via the annealing process, which provides various benefits (e.g., control and flexibility). In some embodiments, manufacture of the bottom electrode 101 also does not have a separate doping step, an additional deposition step in the fabrication of the device. Rather, the amorphous silicon of the semiconductor layer 108 is doped by a bottom heavily doped polysilicon layer, which enables an exact thickness of the bottom electrode to be controlled, instead of more uncontrollable fabrication processes such as an etch or an etch of an additional layer, for example. In some embodiments, where a doped SiGe material is used, no separate anneal process is required to form doped semiconductor layer 108.
The switching medium layer 106 can be comprised of various materials and various layers of material, as discussed in detail below. For example, the switching medium layer 106 can be any suitable material or switching medium having high electrical resistance and having at least partial permeability (e.g., in response to an electric signal) to ions of the second electrode layer 104 or ions that are generated within the switching medium (e.g., metal or oxygen ions). In addition, the material employed for electrically resistive switching medium layer 106 can be compatible with semiconductor fabrication processes (e.g., stacking, etching, masking, deposition, etc.). Examples of such a material can include an amorphous silicon (a-Si) material, a chalcogenide, a silicon on glass, an oxide such as titanium oxide (TiOx), tantalum oxide (TaOx), silicon dioxide (e.g., SiO2), silicon sub-oxide (e.g. SiOx), Hafnium Oxide (HfOx), Nickel Oxide (NiOx), Tungsten Oxide (WOx), Aluminum Oxide (AlOx), Copper Oxide (CuOx), Germanium Oxide (GeOx), Silicon Germanium Oxide (SixGeyOz), Silicon Oxi-Nitride (SiOxNy), Silver Germanium Selenide (AgxGeySez), Silver Selenide (Ag2Se), Copper Sulfite (Cu2S), other oxide, or a suitable combination thereof, which is at least in part porous with respect to the particles, ions or the like.
The first electrode layer 102 can be a suitable metal conductor for a memory cell. Examples can include aluminum, copper, tungsten, titanium, silver, platinum, palladium, other suitable compounds thereof, or a suitable combination of the foregoing. In at least one aspect, metal electrode layer 104 can be a metal bitline, metal wordline, metal dataline, etc. of a memory array. For instance, metal electrode layer 104 can be a metal bitline or metal wordline in a fundamental crossbar memory array. The first electrode layer 102 can be connected to a sensing circuit (e.g., CMOS circuitry, not depicted) to measure current or voltage of cell 100 in conjunction with reading a state of cell 100, for example.
In one or more embodiments, memory cell 100 can comprise one or more other layers not depicted at FIG. 1. For instance, an intermediary layer(s) can be instituted adjacent to one or more of the layers depicted at memory cell 100. As one example, a suitable material layer that mitigates or controls unintended oxidation of switching medium 106 can be positioned between one or more layers of memory cell 100, such as between second electrode layer 104 and switching medium 106. As another example, in some embodiments, memory cell 100 can have fewer layers than depicted in FIG. 1. For instance, second electrode layer 104 or first electrode layer 102 can be removed, and switching material 106 or doped semiconductor layer 108 can electrically contact a conductive bitline, wordline, data line, source line, etc., of a memory array. Accordingly, it is to be appreciated that suitable variations of memory cell 100 known in the art or made known to one of ordinary skill in the art by way of the context provided herein are considered within the scope of the present disclosure.
Turning now to FIG. 2, illustrated is a schematic diagram 200 of an example memory cell (e.g., memory cell 100) at a step in a fabrication process in accordance with various aspects of the disclosure. A layer of silicon oxide or other contact material layer 204 (e.g. field oxide, SiO2) is formed or deposited over a silicon wafer 202. The silicon wafer 202 forms a semiconductor substrate for the memory cell that is to be fabricated. A metal stack 206 is formed on top of the field oxide layer 204. The metal layer can be at least one of Ti, TiN, Al, W, or TiW. In various embodiments, the silicon wafer 202 can include multiple complementary metal-oxide-semiconductor (CMOS) devices.
FIG. 3 illustrates a schematic diagram 300 of an example memory cell at a step in a fabrication process in accordance with various aspects described herein. Diagram 300 depicts a memory cell (e.g. memory cell 100) at a step in the fabrication process where metal lines 302 are patterned or etched from the metal stack 206. These metal lines 302 are interconnected with the bottom electrode of the memory cell. In an embodiment of the subject disclosure, the metal lines 302 run in a direction perpendicular to the perspective of the drawing (i.e., into and out of the page).
FIG. 4 illustrates a schematic diagram 400 of an example memory cell at a step in a fabrication process in accordance with various aspects described herein. Diagram 400 depicts a memory cell (e.g. memory cell 100) at a step in the fabrication process where field oxide 402 is layered around the metal lines 404 and overfilled, such that the field oxide 402 covers the metal lines 404.
FIG. 5 illustrates a schematic diagram 500 of an example memory cell at a step in a fabrication process in accordance with various aspects described herein. Diagram 500 depicts a memory cell (e.g. memory cell 100) at a step in the fabrication process where after the field oxide layer 402 (as shown in FIG. 4) was gapfilled between the metal lines 404, in FIG. 5, the field oxide layer 502 was planarized down to the metal lines 504. In an embodiment, the planarization can be performed using chemical mechanical planarization which uses chemical and mechanical processes to smooth surfaces.
FIG. 6 illustrates a schematic diagram 600 of an example memory cell at a step in a fabrication process in accordance with various aspects described herein. Diagram 600 depicts a memory cell (e.g. memory cell 100) at a step in the fabrication process where a conducting or semiconducting layer 606 of p doped SiGe or Si is layered over the metal lines 604 and oxide layer 602. In other embodiments, the conducting layer 606 can also be composed of a metal or metal alloy. In another embodiment, a hard mask layer 608 of TEOS (tetraethyl orthosilicate) can also be layered over the conducting or semiconducting layer 606. The layering of the conducting or semiconducting layer 606 can be performed in-situ or following a hydrofluoric dip deposit of i-Si via low pressure chemical vapor deposition, plasma enhanced chemical vapor deposition or physical vapor deposition.
Turning now to FIG. 7, illustrated is a schematic diagram 700 of an example memory cell at a step in a fabrication process in accordance with various aspects described herein. Diagram 700 depicts a memory cell (e.g. memory cell 100) at a step in the fabrication process where pillars 704 are etched from the conducting or semiconducting layer 606. These pillars 704 are etched down to the metal lines 702. The pillars, which form a portion of the bottom electrode are the active regions of the two-terminal memory device, in the context of resistive-switching memory, that exhibit a plurality of stable or semi-stable resistive states, each resistive state having a distinct electrical resistance. The pillars 704 thus comprise the switching layer of the memory cell. In various embodiments, the pillars can have a cross section matching a quadrilateral, ovoid, round, or polygonal shape.
Turning now to FIG. 8, illustrated is a schematic diagram 800 of an example memory cell at a step in a fabrication process in accordance with various aspects described herein. Diagram 800 depicts a memory cell (e.g. memory cell 100) at a step in the fabrication process where field oxide 402 is layered around the metal lines 404 and overfilled, such that the field oxide 802 is gapfilled around the pillars 806 and metal lines 804. The pillars 806 and field oxide layer 802 can then be planarized via chemical mechanical planarization with field oxide. The planarization process can shorten the pillars, and in various embodiments, an active metal material can be layered as a collar on the top surface of the pillars 806 and field oxide 802.
Turning now to FIG. 9, illustrated is a schematic diagram 900 of an example memory cell at a step in a fabrication process in accordance with various aspects described herein. Diagram 900 depicts a memory cell (e.g. memory cell 100) at a step in the fabrication process where ions 906 are implanted into the pillars 904 and field oxide layer 902. These ions 910 can be of H, O, Si, Ag, or Ar ions, wherein the ions are selected based on what type of material the pillars 904 are made of. The ion implantation is performed in order to modify the switching properties of the pillars 904, and can variously amorphize crystalline material, enhance oxidation, modify the band gap, or modify defectivity of the pillars (e.g. increasing the defects, porosity, or vacancies of the crystalline material). In some embodiments a SiOx material (0>x>2) may be formed in the upper regions of the pillars.
The ion implantation can be performed with different ion implant profiles to alter the density and depth of the implanted ions 906 in the pillars 904. In various embodiments, the implant power profile is generally around or greater than 5 keV, and the implants ions have a density of at least 5×1014 atoms/cm3.
After the ion implantation is performed, the top metal electrode is formed as shown in FIG. 10. The upper metal layer 1006 is deposited above the oxide 1002 and pillars 1004 at a relatively low temperature of less than 250 degrees centigrade so as to avoid interfering with the ion implantation. The top metal layer 1006 can be formed from one of the active metals described above, e.g. Au, Ag, Pt, etc, in addition to an upper layer of conventional material, e.g. Ti, Ti, TiN, Ag, TiW, W, Al, Cu, combination thereof, etc. Metal lines are shaped from the metal layer 1006 and the metal lines run parallel to the figure. In other words, the metal lines of the top metal electrode run perpendicular to the metal lines of the bottom metal electrode, in various embodiments.
The aforementioned diagrams have been described with respect to interaction between several components of a memory cell, or memory architectures comprised of such memory cells. For example, in some embodiments, the stack of materials may be horizontal, oblique to the substrate, or the like. It should be appreciated that in some suitable alternative aspects of the subject disclosure, such diagrams can include those components and architectures specified therein, some of the specified components/architectures, or additional components/architectures. Sub-components can also be implemented as electrically connected to other sub-components rather than included within a parent architecture. Additionally, it is noted that one or more disclosed processes can be combined into a single process providing aggregate functionality. For instance, a deposition process can comprise a fill or etching process, an anneal process, or the like, or vice versa, to facilitate deposition, filling or etching of memory cell layers by way of an aggregate process. Components of the disclosed architectures can also interact with one or more other components not specifically described herein but known by those of skill in the art.
In view of the exemplary diagrams described supra, process methods that can be implemented in accordance with the disclosed subject matter will be better appreciated with reference to the flow chart of FIG. 11. While for purposes of simplicity of explanation, the methods of FIG. 11 are shown and described as a series of blocks, it is to be understood and appreciated that the claimed subject matter is not limited by the order of the blocks, as some blocks may occur in different orders or concurrently with other blocks from what is depicted and described herein. Moreover, not all illustrated blocks may be required to implement the methods described herein. Additionally, it should be further appreciated that the methods disclosed throughout this specification are capable of being stored on an article of manufacture to facilitate transporting and transferring such methodologies to an electronic device. The term article of manufacture, as used, is intended to encompass a computer program accessible from any suitable computer-readable device, device in conjunction with a carrier, storage medium, or the like, or a suitable combination thereof.
Turning now to FIG. 11, a flowchart of an example method for transferring data with a configurable page size according to one or more embodiments disclosed herein is illustrated. Flowchart 1100 can begin at 1102, where a bottom metal wiring layer is formed above an oxide layer over a semiconductor substrate. Bottom metal electrodes can also be formed from the bottom metal wiring layer.
At 1104, an oxide layer is formed between the bottom metal electrodes (i.e., gapfilling) and a conductive layer is disposed or formed in contact with a top surface of the bottom metal electrodes. At 1106, a plurality of pillars is formed from the conductive layer, and an oxide layer is formed between the plurality of pillars, exposing a top surface of the plurality pillars.
At 1108, ions are implanted into the plurality of pillars from the top surface of the pillars, thereby amorphizing a top portion of the plurality of pillars. At 1110, top metal wiring layers (e.g. active metal and conductor) are formed above the top portion of the pillars, and top metal electrodes are formed from the top metal wiring layer.
Example Operating Environments
In various embodiments of the subject disclosure, disclosed memory architectures can be employed as a standalone or integrated embedded memory device with a CPU or microcomputer. Some embodiments can be implemented, for instance, as part of a computer memory (e.g., random access memory, cache memory, read-only memory, storage memory, or the like). Other embodiments can be implemented, for instance, as a portable memory device. Examples of suitable portable memory devices can include removable memory, such as a secure digital (SD) card, a universal serial bus (USB) memory stick, a compact flash (CF) card, or the like, or suitable combinations of the foregoing. (See, e.g., FIGS. 12 and 13, infra).
NAND FLASH is employed for compact FLASH devices, USB devices, SD cards, solid state drives (SSDs), and storage class memory, as well as other form-factors. Although NAND has proven a successful technology in fueling the drive to scale down to smaller devices and higher chip densities over the past decade, as technology scaled down past 25 nanometer (nm) memory cell technology, the inventors have identified several structural, performance, and reliability problems that became evident to them. These or similar considerations can be addressed by some or all of the disclosed aspects.
In order to provide a context for the various aspects of the disclosed subject matter, FIG. 12, as well as the following discussion, is intended to provide a brief, general description of a suitable environment in which various aspects of the disclosed subject matter can be implemented or processed. While the subject matter has been described above in the general context of electronic memory and process methods for fabricating or operating the electronic memory, those skilled in the art will recognize that the subject disclosure also can be implemented in combination with other components/layers of memory, memory architectures or process methodologies. Moreover, those skilled in the art will appreciate that the disclosed processes can be implemented within a processing system or a computer processor, either alone or in conjunction with a host computer, which can include single-processor or multiprocessor computer systems, mini-computing devices, mainframe computers, as well as personal computers, hand-held computing devices (e.g., PDA, smart phone, watch), microprocessor-based or programmable consumer or industrial electronics, and the like. The illustrated aspects may also be practiced in distributed computing environments where tasks are performed by remote processing devices that are linked through a communications network. However, some, if not all aspects of the claimed innovation can be practiced on stand-alone electronic devices, such as a memory card, FLASH memory module, removable memory, or the like. In a distributed computing environment, program modules can be located in both local and remote memory storage modules or devices.
FIG. 12 illustrates a block diagram of an example operating and control environment 1200 for a memory cell array 1202 according to aspects of the subject disclosure. In at least one aspect of the subject disclosure, memory cell array 1202 can comprise a variety of memory cell technology. Particularly, memory cell array 1202 can comprise two-terminal memory such as resistive memory cells with a resistive switching medium formed via ion implantation to a conductive polysilicon material, as described herein.
A column controller 1206 can be formed adjacent to memory cell array 1202. Moreover, column controller 1206 can be electrically coupled with bit lines of memory cell array 1202. Column controller 1206 can control respective bitlines, applying suitable program, erase or read voltages to selected bitlines.
In addition, operating and control environment 1200 can comprise a row controller 1204. Row controller 1204 can be formed adjacent to column controller 1206, and electrically connected with word lines of memory cell array 1202. Row controller 1204 can select particular rows of memory cells with a suitable selection voltage. Moreover, row controller 1204 can facilitate program, erase or read operations by applying suitable voltages at selected word lines.
A clock source(s) 1208 can provide respective clock pulses to facilitate timing for read, write, and program operations of row control 1204 and column control 1206. Clock source(s) 1208 can further facilitate selection of word lines or bit lines in response to external or internal commands received by operating and control environment 1200. An input/output buffer 1212 can be connected to an external host apparatus, such as a computer or other processing device (not depicted) by way of an I/O buffer or other I/O communication interface. Input/output buffer 1212 can be configured to receive write data, receive an erase instruction, output readout data, and receive address data and command data, as well as address data for respective instructions. Address data can be transferred to row controller 1204 and column controller 1206 by an address register 1210. In addition, input data is transmitted to memory cell array 1202 via signal input lines, and output data is received from memory cell array 1202 via signal output lines. Input data can be received from the host apparatus, and output data can be delivered to the host apparatus via the I/O buffer.
Commands received from the host apparatus can be provided to a command interface 1214. Command interface 1214 can be configured to receive external control signals from the host apparatus, and determine whether data input to the input/output buffer 1212 is write data, a command, or an address. Input commands can be transferred to a state machine 1216.
State machine 1216 can be configured to manage programming and reprogramming of memory cell array 1202. State machine 1216 receives commands from the host apparatus via input/output interface 1212 and command interface 1214, and manages read, write, erase, data input, data output, and like functionality associated with memory cell array 1202. In some aspects, state machine 1216 can send and receive acknowledgments and negative acknowledgments regarding successful receipt or execution of various commands.
To implement read, write, erase, input, output, etc., functionality, state machine 1216 can control clock source(s) 1208. Control of clock source(s) 1208 can cause output pulses configured to facilitate row controller 1204 and column controller 1206 implementing the particular functionality. Output pulses can be transferred to selected bit lines by column controller 1206, for instance, or word lines by row controller 1204, for instance.
The illustrated aspects of the disclosure may also be practiced in distributed computing environments where certain tasks are performed by remote processing devices that are linked through a communications network. In a distributed computing environment, program modules or stored information, instructions, or the like can be located in local or remote memory storage devices.
Moreover, it is to be appreciated that various components described herein can include electrical circuit(s) that can include components and circuitry elements of suitable value in order to implement the embodiments of the subject innovation(s). Furthermore, it can be appreciated that many of the various components can be implemented on one or more IC chips. For example, in one embodiment, a set of components can be implemented in a single IC chip. In other embodiments, one or more respective components are fabricated or implemented on separate IC chips.
In connection with FIG. 13, the systems and processes described below can be embodied within hardware, such as a single integrated circuit (IC) chip, multiple ICs, an application specific integrated circuit (ASIC), or the like. Further, the order in which some or all of the process blocks appear in each process should not be deemed limiting. Rather, it should be understood that some of the process blocks can be executed in a variety of orders, not all of which may be explicitly illustrated herein.
With reference to FIG. 13, a suitable environment 1300 for implementing various aspects of the claimed subject matter includes a computer 1302. The computer 1302 includes a processing unit 1304, a system memory 1306, a codec 1335, and a system bus 1308. The system bus 1308 couples system components including, but not limited to, the system memory 1306 to the processing unit 1304. The processing unit 1304 can be any of various available processors. Dual microprocessors and other multiprocessor architectures also can be employed as the processing unit 1304.
The system bus 1308 can be any of several types of bus structure(s) including the memory bus or memory controller, a peripheral bus or external bus, or a local bus using any variety of available bus architectures including, but not limited to, Industrial Standard Architecture (ISA), Micro-Channel Architecture (MSA), Extended ISA (EISA), Intelligent Drive Electronics (IDE), VESA Local Bus (VLB), Peripheral Component Interconnect (PCI), Card Bus, Universal Serial Bus (USB), Advanced Graphics Port (AGP), Personal Computer Memory Card International Association bus (PCMCIA), Firewire (IEEE 1394), and Small Computer Systems Interface (SCSI).
The system memory 1306 includes volatile memory 1310 and non-volatile memory 1312, which can employ one or more of the disclosed memory architectures, in various embodiments. The basic input/output system (BIOS), containing the basic routines to transfer information between elements within the computer 1302, such as during start-up, is stored in non-volatile memory 1312. In addition, according to present innovations, codec 1335 may include at least one of an encoder or decoder, wherein the at least one of an encoder or decoder may consist of hardware, software, or a combination of hardware and software. Although, codec 1335 is depicted as a separate component, codec 1335 may be contained within non-volatile memory 1312. By way of illustration, and not limitation, non-volatile memory 1312 can include read only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or Flash memory. Non-volatile memory 1312 can employ one or more of the disclosed memory devices, in at least some embodiments. Moreover, non-volatile memory 1312 can be computer memory (e.g., physically integrated with computer 1302 or a mainboard thereof), or removable memory. Examples of suitable removable memory with which disclosed embodiments can be implemented can include a secure digital (SD) card, a compact Flash (CF) card, a universal serial bus (USB) memory stick, or the like. Volatile memory 1310 includes random access memory (RAM), which acts as external cache memory, and can also employ one or more disclosed memory devices in various embodiments. By way of illustration and not limitation, RAM is available in many forms such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), and enhanced SDRAM (ESDRAM) and so forth.
Computer 1302 may also include removable/non-removable, volatile/non-volatile computer storage medium. FIG. 13 illustrates, for example, disk storage 1314. Disk storage 1314 includes, but is not limited to, devices like a magnetic disk drive, solid state disk (SSD) floppy disk drive, tape drive, Jaz drive, Zip drive, LS-100 drive, flash memory card, or memory stick. In addition, disk storage 1314 can include storage medium separately or in combination with other storage medium including, but not limited to, an optical disk drive such as a compact disk ROM device (CD-ROM), CD recordable drive (CD-R Drive), CD rewritable drive (CD-RW Drive) or a digital versatile disk ROM drive (DVD-ROM). To facilitate connection of the disk storage devices 1314 to the system bus 1308, a removable or non-removable interface is typically used, such as interface 1316. It is appreciated that storage devices 1314 can store information related to a user. Such information might be stored at or provided to a server or to an application running on a user device. In one embodiment, the user can be notified (e.g., by way of output device(s) 1336) of the types of information that are stored to disk storage 1314 or transmitted to the server or application. The user can be provided the opportunity to opt-in or opt-out of having such information collected or shared with the server or application (e.g., by way of input from input device(s) 1328).
It is to be appreciated that FIG. 13 describes software that acts as an intermediary between users and the basic computer resources described in the suitable operating environment 1300. Such software includes an operating system 1318. Operating system 1318, which can be stored on disk storage 1314, acts to control and allocate resources of the computer system 1302. Applications 1320 take advantage of the management of resources by operating system 1318 through program modules 1324, and program data 1326, such as the boot/shutdown transaction table and the like, stored either in system memory 1306 or on disk storage 1314. It is to be appreciated that the claimed subject matter can be implemented with various operating systems or combinations of operating systems.
A user enters commands or information into the computer 1302 through input device(s) 1328. Input devices 1328 include, but are not limited to, a pointing device such as a mouse, trackball, stylus, touch pad, keyboard, microphone, joystick, game pad, satellite dish, scanner, TV tuner card, digital camera, digital video camera, web camera, and the like. These and other input devices connect to the processing unit 1304 through the system bus 1308 via interface port(s) 1330. Interface port(s) 1330 include, for example, a serial port, a parallel port, a game port, and a universal serial bus (USB). Output device(s) 1336 use some of the same type of ports as input device(s) 1328. Thus, for example, a USB port may be used to provide input to computer 1302 and to output information from computer 1302 to an output device 1336. Output adapter 1334 is provided to illustrate that there are some output devices 1336 like monitors, speakers, and printers, among other output devices 1336, which require special adapters. The output adapters 1334 include, by way of illustration and not limitation, video and sound cards that provide a means of connection between the output device 1336 and the system bus 1308. It should be noted that other devices or systems of devices provide both input and output capabilities such as remote computer(s) 1338.
Computer 1302 can operate in a networked environment using logical connections to one or more remote computers, such as remote computer(s) 1338. The remote computer(s) 1338 can be a personal computer, a server, a router, a network PC, a workstation, a microprocessor based appliance, a peer device, a smart phone, a tablet, or other network node, and typically includes many of the elements described relative to computer 1302. For purposes of brevity, only a memory storage device 1340 is illustrated with remote computer(s) 1338. Remote computer(s) 1338 is logically connected to computer 1302 through a network interface 1342 and then connected via communication connection(s) 1344. Network interface 1342 encompasses wire or wireless communication networks such as local-area networks (LAN) and wide-area networks (WAN) and cellular networks. LAN technologies include Fiber Distributed Data Interface (FDDI), Copper Distributed Data Interface (CDDI), Ethernet, Token Ring and the like. WAN technologies include, but are not limited to, point-to-point links, circuit switching networks like Integrated Services Digital Networks (ISDN) and variations thereon, packet switching networks, and Digital Subscriber Lines (DSL).
Communication connection(s) 1344 refers to the hardware/software employed to connect the network interface 1342 to the bus 1308. While communication connection 1344 is shown for illustrative clarity inside computer 1302, it can also be external to computer 1302. The hardware/software necessary for connection to the network interface 1342 includes, for exemplary purposes only, internal and external technologies such as, modems including regular telephone grade modems, cable modems and DSL modems, ISDN adapters, and wired and wireless Ethernet cards, hubs, and routers.
As utilized herein, terms “component,” “system,” “architecture” and the like are intended to refer to a computer or electronic-related entity, either hardware, a combination of hardware and software, software (e.g., in execution), or firmware. For example, a component can be one or more transistors, a memory cell, an arrangement of transistors or memory cells, a gate array, a programmable gate array, an application specific integrated circuit, a controller, a processor, a process running on the processor, an object, executable, program or application accessing or interfacing with semiconductor memory, a computer, or the like, or a suitable combination thereof. The component can include erasable programming (e.g., process instructions at least in part stored in erasable memory) or hard programming (e.g., process instructions burned into non-erasable memory at manufacture).
By way of illustration, both a process executed from memory and the processor can be a component. As another example, an architecture can include an arrangement of electronic hardware (e.g., parallel or serial transistors), processing instructions and a processor, which implement the processing instructions in a manner suitable to the arrangement of electronic hardware. In addition, an architecture can include a single component (e.g., a transistor, a gate array, . . . ) or an arrangement of components (e.g., a series or parallel arrangement of transistors, a gate array connected with program circuitry, power leads, electrical ground, input signal lines and output signal lines, and so on). A system can include one or more components as well as one or more architectures. One example system can include a switching block architecture comprising crossed input/output lines and pass gate transistors, as well as power source(s), signal generator(s), communication bus(ses), controllers, I/O interface, address registers, and so on. It is to be appreciated that some overlap in definitions is anticipated, and an architecture or a system can be a stand-alone component, or a component of another architecture, system, etc.
In addition to the foregoing, the disclosed subject matter can be implemented as a method, apparatus, or article of manufacture using typical manufacturing, programming or engineering techniques to produce hardware, firmware, software, or any suitable combination thereof to control an electronic device to implement the disclosed subject matter. The terms “apparatus” and “article of manufacture” where used herein are intended to encompass an electronic device, a semiconductor device, a computer, or a computer program accessible from any computer-readable device, carrier, or media. Computer-readable media can include hardware media, or software media. In addition, the media can include non-transitory media, or transport media. In one example, non-transitory media can include computer readable hardware media. Specific examples of computer readable hardware media can include but are not limited to magnetic storage devices (e.g., hard disk, floppy disk, magnetic strips . . . ), optical disks (e.g., compact disk (CD), digital versatile disk (DVD) . . . ), smart cards, and flash memory devices (e.g., card, stick, key drive . . . ). Computer-readable transport media can include carrier waves, or the like. Of course, those skilled in the art will recognize many modifications can be made to this configuration without departing from the scope or spirit of the disclosed subject matter.
What has been described above includes examples of the subject innovation. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the subject innovation, but one of ordinary skill in the art can recognize that many further combinations and permutations of the subject innovation are possible. Accordingly, the disclosed subject matter is intended to embrace all such alterations, modifications and variations that fall within the spirit and scope of the disclosure. Furthermore, to the extent that a term “includes”, “including”, “has” or “having” and variants thereof is used in either the detailed description or the claims, such term is intended to be inclusive in a manner similar to the term “comprising” as “comprising” is interpreted when employed as a transitional word in a claim.
Moreover, the word “exemplary” is used herein to mean serving as an example, instance, or illustration. Any aspect or design described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects or designs. Rather, use of the word exemplary is intended to present concepts in a concrete fashion. As used in this application, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or”. That is, unless specified otherwise, or clear from context, “X employs A or B” is intended to mean any of the natural inclusive permutations. That is, if X employs A; X employs B; or X employs both A and B, then “X employs A or B” is satisfied under any of the foregoing instances. In addition, the articles “a” and “an” as used in this application and the appended claims should generally be construed to mean “one or more” unless specified otherwise or clear from context to be directed to a singular form.
Additionally, some portions of the detailed description have been presented in terms of algorithms or process operations on data bits within electronic memory. These process descriptions or representations are mechanisms employed by those cognizant in the art to effectively convey the substance of their work to others equally skilled. A process is here, generally, conceived to be a self-consistent sequence of acts leading to a desired result. The acts are those requiring physical manipulations of physical quantities. Typically, though not necessarily, these quantities take the form of electrical or magnetic signals capable of being stored, transferred, combined, compared, and/or otherwise manipulated.
It has proven convenient, principally for reasons of common usage, to refer to these signals as bits, values, elements, symbols, characters, terms, numbers, or the like. It should be borne in mind, however, that all of these and similar terms are to be associated with the appropriate physical quantities and are merely convenient labels applied to these quantities. Unless specifically stated otherwise or apparent from the foregoing discussion, it is appreciated that throughout the disclosed subject matter, discussions utilizing terms such as processing, computing, replicating, mimicking, determining, or transmitting, and the like, refer to the action and processes of processing systems, and/or similar consumer or industrial electronic devices or machines, that manipulate or transform data or signals represented as physical (electrical or electronic) quantities within the circuits, registers or memories of the electronic device(s), into other data or signals similarly represented as physical quantities within the machine or computer system memories or registers or other such information storage, transmission and/or display devices.
In regard to the various functions performed by the above described components, architectures, circuits, processes and the like, the terms (including a reference to a “means”) used to describe such components are intended to correspond, unless otherwise indicated, to any component which performs the specified function of the described component (e.g., a functional equivalent), even though not structurally equivalent to the disclosed structure, which performs the function in the herein illustrated exemplary aspects of the embodiments. In addition, while a particular feature may have been disclosed with respect to only one of several implementations, such feature may be combined with one or more other features of the other implementations as may be desired and advantageous for any given or particular application. It will also be recognized that the embodiments include a system as well as a computer-readable medium having computer-executable instructions for performing the acts and/or events of the various processes.

## Claims

1. A two-terminal memory device, comprising:
a first metal electrode above a first oxide layer over a semiconductor substrate;
a pillar structure comprising:
a contact material layer on a top surface of the first metal electrode, wherein the contact material layer is semiconductive; and
a switching layer on top of the contact material layer, wherein the switching layer comprises a portion of the contact material layer that is ionized, and wherein the switching layer has a lower conductivity than a portion of the contact material layer that is not ionized; and

a second metal electrode above and in contact with a top surface of the pillar, wherein the second metal electrode comprises:
an active metal layer in contact with the top surface of the switching layer of the pillar; and
a conductor layer in contact with the active material.

2. The two-terminal memory device of claim 1, wherein the contact material layer is selected from a group consisting of: doped polysilicon, doped SiGe, or doped siliconcontaining material.

3. The two-terminal memory device of claim 1, the switching layer is selected from a group consisting of: non-conductive amorphous silicon, intrinsic semiconductor material, non-stoichiometric silicon oxide.

4. The two-terminal memory device of claim 1, wherein the active metal layer is selected from a group consisting of: aluminum, copper, tungsten, titanium, silver, platinum, palladium, Ti, TiN, Ag, TiW, and W.

5. The two-terminal memory device of claim 1, wherein the contact material layer is ionized with ions selected from a group consisting of: H, O, Si, Ag, or Ar.

6. The two-terminal memory device of claim 1, wherein the pillar structure is surrounded by an oxide layer.

7. The two-terminal memory device of claim 6, wherein the active material layer comprises a collar of an active metal material above the top surface of the pillar structure.

8. The two-terminal memory device of claim 6, wherein a cross-section of the pillar structure is selected from a group consisting of: a quadrilateral, an ovoid, round, and polygonal.

9. The two-terminal memory device of claim 1, wherein the implanted ions amorphize a structure of the switching layer.

10. The two-terminal memory device of claim 1, wherein the implanted ions comprise an ion implant profile having an implant power of at least 5 keV.

11. The two-terminal memory device of claim 1, wherein the implanted ions have a density of at least 5×1014 atoms/cm3.

12. The two-terminal memory device of claim 1, wherein the first oxide layer comprises a blanket oxide layer above the bottom metal electrodes that is planarized to expose a top surface of the bottom metal electrodes.

13. The two-terminal memory device of claim 1, further comprising a second oxide layer comprising a blanket oxide layer above the pillar that is planarized to expose a top surface of the pillar.

14. An electronic device comprising an electronic memory unit, the electronic memory unit comprising one or more arrays of multi-state memory cells configured to store information, the multi-state memory cells comprising:
a first metal electrode above a first oxide layer over a semiconductor substrate;
a pillar structure comprising:
a contact material layer formed of a semiconductive contact material on a top surface of the first metal electrode, and a switching layer on top of the contact material layer, wherein the switching layer comprises a portion of the conductive contact material layer that is ionized to decrease conductivity of the switching layer relative to a portion of the contact material layer that is not ionized; and
a second metal electrode above and in contact with a top surface of the pillar, wherein the second metal electrode comprises:
an active metal layer in contact with the top surface of the switching layer of the pillar, and a conductor layer in contact with the active metal layer.

15. The electronic device of claim 14, wherein the contact material is selected from a group consisting of: doped polysilicon, doped SiGe, or doped silicon-containing material.

16. The electronic device of claim 14, wherein the switching layer is ionized via ion implantation with an ion implant profile having an implant power of at least 5 keV and wherein the implanted ions have a density of at least 5×1014 atoms/cm3.

17. The electronic device of claim 14 wherein the active metal layer comprises a material selected from a group consisting of: aluminum, copper, tungsten, titanium, silver, platinum, palladium, Ti, TiN, Ag, TiW, and W.

18. The electronic device of claim 14
wherein the conductor layer comprises a barrier material layer on top of the active metal layer and a conductive material layer on top of the barrier material layer;
wherein the barrier material layer is selected from a group consisting of: a tungsten material, a titanium material, and a metal nitride; and
wherein the conductive material layer is selected from a group consisting of: aluminum and copper.

19. The electronic device of claim 14 wherein the portion of the conductive contact material layer that is ionized to decrease conductivity is selected from a group consisting of: undoped amorphous silicon, non-stoichiometric silicon oxide, and SiOx.

20. The electronic device of claim 14 wherein the portion of the conductive contact material that is ionized to decrease conductivity contacts the active metal layer.