Abstract:
A memory device is configured to identify a set of bit cells to be changed from a first state to a second state. In some examples, the memory device may apply a first voltage to the set of bit cells to change a least a first portion of the set of bit cells to the second state. In some cases, the memory device may also identify a second portion of the bit cells that remained in the first state following the application of the first voltage. In these cases, the memory device may apply a second voltage having a greater magnitude, duration, or both to the second portion of the set of bit cells in order to set the second portion of bit cells to the second state.
Abstract:
In one aspect, the present inventions are directed to a magnetoresistive structure having a tunnel junction, and a process for manufacturing such a structure. The tunnel barrier may be formed between a free layer and a fixed layer in a plurality of repeating process of depositing a metal material and oxidizing at least a portion of the metal material. Where the tunnel barrier is formed by deposition of at least three metal materials interceded by an associated oxidization thereof, the oxidation dose associated with the second metal material may be greater than the oxidation doses associated with the first and third metal materials. In certain embodiments, the fixed layer may include a discontinuous layer of a metal, for example, Ta, in the fixed layer between two layers of a ferromagnetic material.
Abstract:
Memory cells in a spin-torque magnetic random access memory (MRAM) include at least two magnetic tunnel junctions within each memory cell, where each memory cell only stores a single data bit of information. Access circuitry coupled to the memory cells are able to read from and write to a memory cell even when one of the magnetic tunnel junctions within the memory cell is defective and is no longer functional. Self-referenced and referenced reads can be used in conjunction with the multiple magnetic tunnel junction memory cells. In some embodiments, writing to the memory cell forces all magnetic tunnel junctions into a known state, whereas in other embodiments, a subset of the magnetic tunnel junctions are forced to a known state.
Abstract:
A magnetoresistive memory element (for example, a spin-torque magnetoresistive memory element), includes first and second dielectric layers, wherein at least one of the dielectric layers is a magnetic tunnel junction. The memory element also includes a free magnetic layer having a first surface in contact with the first dielectric layer and a second surface in contact with the second dielectric layer. The free magnetic layer, which is disposed between the first and second dielectric layers, includes (i) a first high-iron interface region located along the first surface of the free magnetic layer, wherein the first high-iron interface region has at least 50% iron by atomic composition, and (ii) a first layer of ferromagnetic material adjacent to the first high-iron interface region, the first high-iron interface region between the first layer of ferromagnetic material and the first surface of the free magnetic layer.
Abstract:
An MRAM device, and a process for manufacturing the device, provides improved breakdown distributions, a reduced number of bits with a low breakdown voltage, and an increased MR, thereby improving reliability, manufacturability, and error-free operation. A tunnel barrier is formed between a free layer and a fixed layer in three repeating steps of forming a metal material, interceded by oxidizing each of the metal materials. The oxidization of the third metal material is greater than the dose of the first metal, but less than the dose of the second metal. The fixed layer may include a discontinuous layer of a metal, for example, Ta, in the fixed layer between two layers of a ferromagnetic material.
Abstract:
A sensor and fabrication process are provided for forming reference layers with substantially orthogonal magnetization directions having zero offset with a small compensation angle. An exemplary embodiment includes a sensor layer stack of a magnetoresistive thin-film based magnetic field sensor, the sensor layer stack comprising a pinning layer; a pinned layer including a layer of amorphous material over the pinning layer, and a first layer of crystalline material over the layer of amorphous material; a nonmagnetic coupling layer over the pinned layer; a fixed layer over the nonmagnetic coupling layer; a tunnel barrier over the fixed layer; and a sense layer over the nonmagnetic intermediate layer. Another embodiment includes a sensor layer stack where a pinned layer including two crystalline layers separated by a amorphous layer.
Abstract:
A semiconductor process integrates three bridge circuits, each include magnetoresistive sensors coupled as a Wheatstone bridge on a single chip to sense a magnetic field in three orthogonal directions. The process includes various deposition and etch steps forming the magnetoresistive sensors and a plurality of flux guides on one of the three bridge circuits for transferring a “Z” axis magnetic field onto sensors orientated in the XY plane.
Abstract:
A sensor and fabrication process are provided for forming reference layers with substantially orthogonal magnetization directions having zero offset with a small compensation angle. An exemplary embodiment includes a sensor layer stack of a magnetoresistive thin-film based magnetic field sensor, the sensor layer stack comprising a pinning layer; a pinned layer including a layer of amorphous material over the pinning layer, and a first layer of crystalline material over the layer of amorphous material; a nonmagnetic coupling layer over the pinned layer; a fixed layer over the nonmagnetic coupling layer; a tunnel barrier over the fixed layer; and a sense layer over the nonmagnetic intermediate layer. Another embodiment includes a sensor layer stack where a pinned layer including two crystalline layers separated by a amorphous layer.
Abstract:
The present disclosure is directed to exemplary methods of manufacturing a magnetoresistive device. In one aspect, a method may include forming one or more regions of a magnetoresistive stack on a substrate, wherein the substrate includes at least one electronic device. The method also may include performing a sole annealing process on the substrate having the one or more magnetoresistive regions formed thereon, wherein the sole annealing process is performed at a first minimum temperature. Subsequent to performing the sole annealing process, the method may include patterning or etching at least a portion of the magnetoresistive stack. Moreover, subsequent to the step of patterning or etching the portion of the magnetoresistive stack, the method may include performing all additional processing on the substrate at a second temperature below the first minimum temperature.
Abstract:
A magnetoresistive element (e.g., a spin-torque magnetoresistive memory element) includes a fixed magnetic layer, a free magnetic layer, having a high-iron alloy interface region located along a surface of the free magnetic layer, wherein the high-iron alloy interface region has at least 50% iron by atomic composition, and a first dielectric, disposed between the fixed magnetic layer and the free magnetic layer. The magnetoresistive element further includes a second dielectric, having a first surface that is in contact with the surface of the free magnetic layer, and an electrode, disposed between the second dielectric and a conductor. The electrode includes: (i) a non-ferromagnetic portion having a surface that is in contact with a second surface of the second dielectric, and (ii) a second portion having at least one ferromagnetic material disposed between the non-ferromagnetic portion of the electrode and the conductor.