Micron Technology Incorporated

Nve Corporation

James G Deak

Hasan Nejad

Joel A Drewes

Mark E Tuttle

James M Daughton

Arthur V Pohm

Maciej M Kowalewski

James W Daughton

A spin dependent tunneling device includes an electrically insulative material intermediate layer, a magnetization reference layer on one of the opposite major surfaces of the intermediate layer, and a memory film of a magnetostrictive, anisotropic ferromagnetic material on the other of the opposite major surfaces of the intermediate layer. The memory film material has a magnetization directed at an angle with respect to the relatively fixed direction of the magnetization reference layer, due to an effective magnetic bias field being present, in a first kind of stress condition with unequal coercivities for external magnetic fields applied in opposite directions. In one kind of stress condition the device has a coercivity with a magnitude exceeding that of the effective magnetic bias field, and in another kind of stress condition, the device has a coercivity with a magnitude less than that of the effective magnetic bias field.

Spin dependent tunneling devices with magnetization states based on stress conditions

A tamper sensing system mounted with respect to a protected structure so as to have corresponding stress changes occur therein in response to selected kinds of tamperings with said protected structure comprising a first pair of stress affected magnetoresistive memory devices each capable of having a magnetic material layer therein established in a selected one of a pair of alternative magnetization states if in a first kind of stress condition and of being established in a single magnetization state if in an alternative second kind of stress condition, and the magnetic material layer in each having a magnetization in a first direction in one of the pair of alternative magnetization states and in a second direction in that remaining one of the pair of magnetization states. A first magnetizing electrical conductor extends adjacent to each of the first pair of stress affected magnetoresistive memory devices to establish said magnetic material layer in that one of said pair of alternative magnetization states thereof so as to have its said corresponding magnetization be oppositely directed with respect to said magnetization of that other. The first pair of stress affected magnetoresistive memory devices can each be provided by a spin dependent tunneling device having differing numbers of magnetization states available thereto depending on whether being in differing ones of alternative stress conditions.

Stressed magnetoresistive tamper detection devices

A ferromagnetic thin-film based device that transitioned between alternative magnetic states thereof through having electrical currents established therethrough and has both a reference magnetization and a free layer magnetization provided therein by vortex magnetizations.

Vortex spin momentum transfer magnetoresistive device

An MRAM device includes an array of magnetic memory cells having an upper conductive layer and a lower conductive layer separated by a barrier layer. To reduce the likelihood of electrical shorting across the barrier layers of the memory cells, spacers can be formed around the upper conductive layer and, after the layers of the magnetic memory cells have been etched, the memory cells can be oxidized to transform any conductive particles that are deposited along the sidewalls of the memory cells as byproducts of the etching process into nonconductive particles. Alternatively, the lower conductive layer can be repeatedly subjected to partial oxidation and partial etching steps such that only nonconductive particles can be thrown up along the sidewalls of the memory cells as byproducts of the etching process.

System and method for reducing shorting in memory cells

A ferromagnetic thin-film based digital memory system having memory cells interconnected in a grid that are selected through voltage values supplied coincidently on interconnections made thereto for changing states thereof and determining present states thereof through suitable biasing of grid interconnections.

Cross-point magnetoresistive memory

A method is provided for fabricating a fixed layer for a MRAM device. The method includes providing the fixed layer. The fixed layer includes an antiferromagnetic pinning layer over a substrate and a ferromagnetic pinned layer over the pinning layer, the pinned layer having a first thickness. The fixed layer further includes a spacer layer over the pinned layer, and a ferromagnetic reference layer over the spacer layer, the reference layer having a second thickness. The method further includes annealing the fixed layer using a temporal temperature/magnetic field profile, the profile having a maximum magnetic field magnitude (H). The profile is selected based on the first thickness of the pinned layer and the second thickness of the reference layer.

Magnetic annealing sequences for patterned MRAM synthetic antiferromagnetic pinned layers

The present invention provides a method of forming an MRAM cell which minimizes the occurrence of electrical shorts during fabrication. A first conductor in a trench is provided in an insulating layer and an upper surface of the insulating layer and the first conductor is planarized. Then, a dielectric layer is deposited to a thickness slightly greater than the desired final thickness of a sense layer, which is formed later. The dielectric layer is then patterned and etched to form an opening for the cell shapes over the first conductor. Then, a permalloy is electroplated in the cell shapes to form the sense layer. The sense layer and dielectric layer are flattened and then a nonmagnetic tunnel barrier layer is deposited. Finally, the pinned layer is formed over the tunnel barrier layer.

Method for forming MRAM bit having a bottom sense layer utilizing electroless plating

A tamper detecting enclosure arrangement for enclosures containing an interior space in which a protected item is positioned having a magnetoresistive sensing memory storage cell positioned in or near the protected item in the enclosure having a two state offset magnetoresistance versus externally applied magnetic field. A magnet is positioned at a selected separation distance from the magnetoresistive sensing memory storage cell to thereby provide a magnetic field about the magnetoresistive sensing memory storage cell if said enclosure has not been opened in such a manner as to result in substantially increasing said separation distance.

Enclosure tamper detection and protection

The present invention seeks to reduce the amount of current required for a write operation by using a process for forming the read conductor within a recessed write conductor, the write conductor itself formed within a trench of an insulating layer. The present invention protects the MTJ from the voltages created by the write conductor by isolating the write conductor and enabling the reduction of current necessary to write a bit of information.

Self-aligned, low-resistance, efficient memory array

A magnetic memory element includes a sense structure, a tunnel barrier adjacent the sense structure, and a synthetic antiferromagnet (SAF) adjacent the tunnel barrier on a side opposite the sense structure. The SAF includes an antiferromagnetic structure adjacent a ferromagnetic seed layer. The ferromagnetic seed layer provides a texture so that the antiferromagnetic structure deposited on the ferromagnetic seed layer has reduced pinning field dispersion.

Magnetic memory having synthetic antiferromagnetic pinned layer

MRAM structures employ the magnetic properties of layered magnetic and non-magnetic materials to read memory storage logic states. Improvements in switching reliability may be achieved by altering the shape of the layered magnetic stack structure. Forming recessed regions with sloped interior walls in an ILD layer prior to depositing the layered magnetic stack structure produces a significant advantage over the prior art by allowing a CMP process to be used to define the magnetic bit shapes. The sloped interior walls of the recessed regions, which is singular to the present invention, provide a unique formation and shaping of the magnetic stack structure, which may reduce the magnetic coupling effect between magnetic layers of the magnetic stack structure.

Process flow for building MRAM structures

The invention includes a construction comprising an MRAM device between a pair of conductive lines. Each of the conductive lines can generate a magnetic field encompassing at least a portion of the MRAM device. Each of the conductive lines is surrounded on three sides by magnetic material to concentrate the magnetic fields generated by the conductive lines at the MRAM device. The invention also includes a method of forming an assembly containing MRAM devices. A plurality of MRAM devices are formed over a substrate. An electrically conductive material is formed over the MRAM devices, and patterned into a plurality of lines. The lines are in a one-to-one correspondence with the MRAM devices and are spaced from one another. After the conductive material is patterned into lines, a magnetic material is formed to extend over the lines and within spaces between the lines.

Magnetoresistive memory device assemblies, and methods of forming magnetoresistive memory device assemblies

A magnetic random access memory (MRAM) is compensated for write current shunting by varying the bit size of each MRAM cell with position along the write line. The MRAM includes a plurality of magnetic tunnel junction memory cells arranged in an array of columns and rows. The width of each memory cell increases along a write line to compensate for write current shunting.

Growing community of inventors

Boise, ID, United States of America

James G Deak