Abstract:
Embodiments of the invention generally relate to nonvolatile memory devices, such as a ReRAM cells, and methods for manufacturing such memory devices, which includes optimized, atomic layer deposition (ALD) processes for forming metal oxide film stacks. The metal oxide film stacks contain a metal oxide coupling layer disposed on a metal oxide host layer, each layer having different grain structures/sizes. The interface disposed between the metal oxide layers facilitates oxygen vacancy movement. In many examples, the interface is a misaligned grain interface containing numerous grain boundaries extending parallel to the electrode interfaces, in contrast to the grains in the bulk film extending perpendicular to the electrode interfaces. As a result, oxygen vacancies are trapped and released during switching without significant loss of vacancies. Therefore, the metal oxide film stacks have improved switching performance and reliability during memory cell applications compared to traditional hafnium oxide based stacks of previous memory cells.
Abstract:
Measuring current-voltage (I-V) characteristics of a solar cell using a lamp that emits light, a substrate that includes a plurality of solar cells, a positive electrode attached to the solar cells, and a negative electrode peripherally deposited around each of the solar cells and connected to a common ground, an articulation platform coupled to the substrate, a multi-probe switching matrix or a Z-stage device, a programmable switch box coupled to the multi-probe switching matrix or Z-stage device and selectively articulating the probes by raising the probes until in contact with at least one of the positive electrode and the negative electrode and lowering the probes until contact is lost with at least one of the positive electrode and the negative electrode, a source meter coupled to the programmable switch box and measuring the I-V characteristics of the substrate.
Abstract:
Filament size and shape in a ReRAM stack can be controlled by doping layers of a variable-resistance stack to change the crystallization temperature. This changes the density of the grain boundaries that form during annealing and provide minimal-resistance paths for the migration of charged defects. Hf, Zr, or Ti decreases the crystallization temperature and narrows the filament, while Si or N increases the crystallization temperature and widens the filament. Tapered filaments are of interest: The narrow tip requires little energy to break and re-form, enabling the cell to operate at low power, yet the wider body and base are insensitive to entropic behavior of small numbers of defects, enabling the cell to retain data for long periods.
Abstract:
A nonvolatile sample and hold circuit can include a resistive switching circuit, a sample circuit, a reset circuit, and a converter circuit. The resistive switching circuit can be operable to accept an input voltage Vg, and provide a resistance response Rrs that corresponds to the input signal Vg. The sampling circuit can be operable to sample an input signal such as an input voltage Vin, to provide a sampled voltage Vg. The reset circuit can be operable to reset the resistive switching circuit to a high resistance state. The converter circuit can be operable to convert the resistive switching circuit to an output voltage. The novel sample and hold circuit can have no issues related to charge injection, no settling time and instantaneous sampling time, together with potentially infinite hold time.
Abstract:
A variable resistance layer in a resistive non-volatile memory (ReRAM) cell changes its resistance in response to an applied signal by breaking and re-forming covalent bonds (e.g., in sub-stoichiometric silicon oxide). Resistivity decreases with increasing density of broken “dangling” bonds. When an electric field is applied, more dangling bonds are created, forming a filament of defects through which charge carriers can tunnel through the covalent layer. Passing a high current through the dangling-bond filament causes localized heating that re-forms the bonds. Optionally, an ionic oxide or nitride layer in contact with the covalent switching layer may serve as an oxygen source for thermal re-oxidation during the heating.
Abstract:
A thin cap of metal alloy or metal-silicon compound is formed over a ternary oxide or ternary nitride ReRAM embedded resistor. At least one metal in the cap is the same as a metal in the embedded resistor. If the cap oxidizes slightly (e.g., incidental to a vacuum break, anneal, or subsequent treatment or deposition), the overall resistance of the memory cell is much less affected than it would be by the same amount of oxidation directly on a surface of the uncapped oxide or nitride embedded resistor.
Abstract:
A method and system includes a first substrate and a second substrate, each substrate comprising a predetermined baseline transmittance value at a predetermine wavelength of light, processing regions on the first substrate by combinatorially varying at least one of materials, process conditions, unit processes, and process sequences associated with the graphene production, performing a first characterization test on the processed regions on the first substrate to generate first results, processing regions on a second substrate in a combinatorial manner by varying at least one of materials, process conditions, unit processes, and process sequences associated with the graphene production based on the first results of the first characterization test, performing a second characterization test on the processed regions on the second substrate to generate second results, and determining whether at least one of the first substrate and the second substrate meet a predetermined quality threshold based on the second results.
Abstract:
Embodiments of the invention include nonvolatile memory elements and memory devices comprising the nonvolatile memory elements. Methods for forming the nonvolatile memory elements are also disclosed. The nonvolatile memory element comprises a first electrode layer, a second electrode layer, and a plurality of layers of an oxide disposed between the first and second electrode layers. One of the oxide layers has linear resistance and substoichiometric composition, and the other oxide layer has bistable resistance and near-stoichiometric composition. Preferably, the sum of the two oxide layer thicknesses is between about 20 Å and about 100 Å, and the oxide layer with bistable resistance has a thickness between about 25% and about 75% of the total thickness. In one embodiment, the oxide layers are formed using reactive sputtering in an atmosphere with controlled flows of argon and oxygen.
Abstract:
Provided are resistive random access memory (ReRAM) cells and methods of fabricating thereof. A ReRAM cell includes an embedded resistor and a variable resistance layer that are interconnected in series by, for example, stacking the two. The embedded resistor prevents excessive electrical currents through the variable resistance layer thereby preventing its over-programming. The embedded resistor is configured to maintain a constant resistance during the operation of the ReRAM cell, such as applying switching currents and changing the resistance of the variable resistance layer. Specifically, the embedded resistor may be electrically broken down during fabrication of the ReRAM cell to improve the subsequent stability of the embedded resistance to electrical fields during operation of the ReRAM cell. The embedded resistor may be made from materials that allow this initial breakdown and to avoid future breakdowns, such metal silicon nitrides, metal aluminum nitrides, and metal boron nitrides.
Abstract:
A nonvolatile sample and hold circuit can include a resistive switching circuit, a sample circuit, a reset circuit, and a converter circuit. The resistive switching circuit can be operable to accept an input voltage Vg, and provide a resistance response Rrs that corresponds to the input signal Vg. The sampling circuit can be operable to sample an input signal such as an input voltage Vin, to provide a sampled voltage Vg. The reset circuit can be operable to reset the resistive switching circuit to a high resistance state. The converter circuit can be operable to convert the resistive switching circuit to an output voltage. The novel sample and hold circuit can have no issues related to charge injection, no settling time and instantaneous sampling time, together with potentially infinite hold time.