Crocus-technology Sa

Commissariat a L'energie Atomique

Centre National De La Recherche Scientifique

Commissariat À L'énergie Atomique Et Aux Énergies Alternatives

Crocus Technology Inc.

Ioan Lucian Prejbeanu

Lucien Lombard

Kenneth MacKay

Bernard Dieny

Ricardo Sousa

Clarisse Ducruet

Bertrand Francis Cambou

Jean-Pierre Nozieres

Sebastien Bandiera

Quentin Stainer

Olivier Redon

Jean-Pierre Nozières

Jerome Moritz

Céline Portemont

Sébastien Bandiera

Jérémy Alvarez-Hérault

Jérôme Moritz

Kenneth Mackay

Alvarez-Hérault Jérémy

The present disclosure concerns a method of fabricating a magnetic tunnel junction suitable for a magnetic random access memory (MRAM) cell and comprising a first ferromagnetic layer, a tunnel barrier layer, and a second ferromagnetic layer, comprising: forming the first ferromagnetic layer; forming the tunnel barrier layer; and forming the second ferromagnetic layer; wherein said forming the tunnel barrier layer comprises depositing a layer of metallic Mg; and oxidizing the deposited layer of metallic Mg such as to transform the metallic Mg into MgO; the step of forming the tunnel barrier layer being performed at least twice such that the tunnel barrier layer comprises at least two layers of MgO.

Magnetic tunnel junction with an improved tunnel barrier

The present disclosure concerns a magnetic random access memory (MRAM) cell suitable for performing a thermally assisted write operation or a spin torque transfer (STT) based write operation, comprising a magnetic tunnel junction comprising a top electrode; a tunnel barrier layer comprised between a first ferromagnetic layer having a first magnetization direction, and a second ferromagnetic layer having a second magnetization direction adjustable with respect to the first magnetization direction; a front-end layer; and a magnetic or metallic layer on which the second ferromagnetic layer is deposited; the second ferromagnetic layer being comprised between the front-end layer and the tunnel barrier layer and having a thickness comprised between about 0.5 nm and about 2 nm, such that magnetic tunnel junction has a magnetoresistance larger than about 100%. The MRAM cell disclosed herein has lower power consumption compared to conventional MRAM cells.

Low power magnetic random access memory cell

Method for writing and reading a plurality of data bits to a magnetic random access memory (MRAM) cell including a magnetic tunnel junction including a reference magnetic layer having a reference magnetization, a tunnel barrier layer, and a SAF storage magnetic layer including a first and second storage magnetization being coupled antiparallel through a storage coupling layer and freely orientable at a high temperature threshold. The method includes: heating the magnetic tunnel junction to the high temperature threshold; and applying a write magnetic field to orient the first and second storage magnetization; wherein the high temperature threshold includes one of a first or third high temperature threshold such as to orient the first storage magnetization respectively antiparallel or parallel to the second storage magnetization; or a second high temperature threshold such as to orient the first storage magnetization with an angle below 180&#xb0; with respect to the second storage magnetization.

Thermally assisted multi-level MRAM cell and method for writing a plurality of bits in the MRAM cell

MRAM cell including a magnetic tunnel junction including a reference layer, a storage layer having a storage magnetization, a tunnel barrier layer between the reference and the storage layers; and an antiferromagnetic layer exchange-coupling the storage layer such as to pin the storage magnetization at a low temperature threshold and free it at a high temperature threshold. The storage layer includes a first ferromagnetic layer in contact with the tunnel barrier layer, a second ferromagnetic layer in contact with the antiferromagnetic layer, and a low saturation magnetization storage layer including a ferromagnetic material and a non-magnetic material. The MRAM cell can be written with improved reliability.

Thermally-assisted MRAM cells with improved reliability at writing

A magnetic random access memory (MRAM) cell including a magnetic tunnel junction containing: a storage layer including at least one storage ferromagnetic layer, each storage ferromagnetic layer having a storage magnetization; an antiferromagnetic storage layer pinning the storage magnetization at a low threshold temperature and freeing them at a high temperature threshold; a reference layer; and a tunnel barrier layer between the reference layer and the storage layer. The magnetic tunnel junction also includes a free ferromagnetic layer having a free magnetization adapted to induce a magnetic stray field magnetically coupling the free ferromagnetic layer with the storage layer; such that the storage magnetization can be switched by the magnetic stray field when the magnetic tunnel junction is at the high temperature threshold. The disclosed MRAM cell has low power consumption.

Magnetic random access memory (MRAM) cell with low power consumption

A magnetic logic unit (MLU) cell includes a first magnetic tunnel junction and a second magnetic tunnel junction, each magnetic tunnel junction including a first magnetic layer having a first magnetization, a second magnetic layer having a second magnetization, and a tunnel barrier layer between the first and second layer. A field line for passing a field current such as to generate an external magnetic field is adapted to switch the first magnetization. The first magnetic layer is arranged such that the magnetic tunnel junction magnetization varies linearly with the generated external magnetic field. An MLU amplifier includes a plurality of the MLU cells. The MLU amplifier has large gains, extended cut off frequencies and improved linearity.

Magnetic logic unit (MLU) cell and amplifier having a linear magnetic signal

Magnetic element including a first magnetic layer having a first magnetization; a second magnetic layer having a second magnetization; a tunnel barrier layer between the first and the second magnetic layers; and an antiferromagnetic layer exchanged coupling the second magnetic layer such that the second magnetization is pinned below a critical temperature of the antiferromagnetic layer, and can be freely varied when the antiferromagnetic layer is heated above that critical temperature. The magnetic element also includes an oxygen gettering layer between the second magnetic layer and the antiferromagnetic layer, or within the second magnetic layer. The magnetic element has reduced insertion of oxygen atoms in the antiferromagnetic layer and possibly reduced diffusion of manganese in the second magnetic layer resulting in an enhanced exchange bias and/or enhanced resistance to temperature cycles and improved life-time.

Magnetoresistive element with oxygen getting layer having enhanced exchange bias and thermal stability for spintronic devices

Method for writing to a MRAM cell including a magnetic tunnel junction including a first and second ferromagnetic layer, and a tunnel barrier layer; and a bipolar transistor in electrical connection with one end of the magnetic tunnel junction, the bipolar transistor being arranged for controlling the passing and polarity of a heating current in the magnetic tunnel junction. The method includes a sequence of writing steps, each writing step including passing the heating current in the magnetic tunnel junction such as to heat it to a high temperature threshold; and once the magnetic tunnel junction has reached the high temperature threshold, adjusting a second magnetization of the second ferromagnetic layer for writing a write data; wherein during one of the writing steps, the polarity of the heating current is reversed from one during the subsequent writing step. The method allows for an increased lifespan of the MRAM cell.

Method for writing to a random access memory (MRAM) cell with improved MRAM cell lifespan

MRAM element having a magnetic tunnel junction including a reference layer, a storage layer, a tunnel barrier layer between the reference and storage layers, and a storage antiferromagnetic layer. The storage antiferromagnetic layer has a first function of exchange-coupling a storage magnetization of the storage layer and a second function of heating the magnetic tunnel junction when a heating current in passed in the magnetic tunnel junction. The MRAM element has better data retention and low writing temperature.

MRAM element with low writing temperature

A thermally assisted switching MRAM element including a magnetic tunnel junction including a reference layer having a reference magnetization; a storage layer having a storage magnetization; a tunnel barrier layer included between the storage layer and the reference layer; and a storage antiferromagnetic layer exchange-coupling the storage layer such as to pin the storage magnetization at a low temperature threshold and to free it at a high temperature threshold. The antiferromagnetic layer includes: at least one first antiferromagnetic layer having a first storage blocking temperature, and at least one second antiferromagnetic layer having a second storage blocking temperature; wherein the first storage blocking temperature is below 200&#xb0; C. and the second storage blocking temperature is above 250&#xb0; C. The MRAM element combines better data retention compared with known MRAM elements with low writing mode operating temperature.

MRAM element having improved data retention and low writing temperature

A magnetic logic unit (MLU) cell includes a first and second magnetic tunnel junction, each including a first magnetic layer having a first magnetization, a second magnetic layer having a second magnetization, and a barrier layer; and a field line for passing a field current such as to generate an external magnetic field adapted to adjust the first magnetization. The first and second magnetic layers and the barrier layer are arranged such that the first magnetization is magnetically coupled antiparallel with the second magnetization through the barrier layer. The MLU cell also includes a biasing device arranged for applying a static biasing magnetic field oriented substantially parallel to the external magnetic field such as to orient the first magnetization at about 90&#xb0; relative to the second magnetization, the first and second magnetizations being oriented symmetrically relative to the direction of the external magnetic field.

MRAM cell comprising a magnetic tunnel junction comprising a storage layer having a net storage magnetization being adjustable when the magnetic tunnel junction is at a high temperature threshold and being pinned at a low temperature threshold; a sense layer having a reversible sense magnetization; and a tunnel barrier layer between the sense and storage layers; at least one of the storage and sense layer comprising a ferrimagnetic 3d-4f amorphous alloy material comprising a sub-lattice of 3d transition metals atoms providing a first magnetization and a sub-lattice of 4f rare-earth atoms providing a second magnetization, such that at a compensation temperature of said at least one of the storage layer and the sense layer, the first magnetization and the second magnetization are substantially equal. The disclosed MRAM cell can be written and read using a small writing and reading field, respectively.

Self-reference magnetic random access memory (MRAM) cell comprising ferrimagnetic layers

The present disclosure concerns a method for writing to a self-referenced MRAM cell comprising a magnetic tunnel junction comprising: a storage layer including a first ferromagnetic layer having a first storage magnetization, a second ferromagnetic layer having a second storage magnetization, and a non-magnetic coupling layer separating the first and second ferromagnetic layers; a sense layer having a free sense magnetization; and a tunnel barrier layer included between the sense and storage layers; the first and second ferromagnetic layers being arranged such that a dipolar coupling between the storage) and the sense layers is substantially null; the method comprising: switching the second ferromagnetic magnetization by passing a spin-polarized current in the magnetic tunnel junction; wherein the spin-polarized current is polarized when passing in the sense layer, in accordance with the direction of the sense magnetization. The MRAM cell can be written with low power consumption.

Self-referenced MRAM cell and method for writing the cell using a spin transfer torque write operation

The present disclosure concerns a method for writing to a MRAM cell comprising a magnetic tunnel junction formed from a storage layer having a storage magnetization; a reference layer having a reference magnetization; and a tunnel barrier layer included between the sense and storage layers; and a current line electrically connected to said magnetic tunnel junction; the method comprising: passing a heating current in the magnetic tunnel junction for heating the magnetic tunnel junction; passing a field current for switching the storage magnetization in a written direction in accordance with the polarity of the field current. The magnitude of the heating current is such that it acts as a spin polarized current and can adjust the storage magnetization; and the polarity of the heating current is such as to adjust the storage magnetization substantially towards said written direction.

MRAM cell and method for writing to the MRAM cell using a thermally assisted write operation with a reduced field current

Magnetic random access memory (MRAM) element suitable for a thermally-assisted write operation and for a self-referenced read operation, including a magnetic tunnel junction portion having a first portion and a second portion, each portion including a storage layer, a sense layer, and a tunnel barrier layer; the magnetic tunnel junction further including an antiferromagnetic layer between the two storage layers and pinning a storage magnetization of each of the storage layers below a critical temperature, and freeing them at and above the critical temperature; such that, during a write operation, a free magnetization of each of the sense layer is magnetically saturable according to a direction of a write magnetic field when applied; and the storage magnetizations are switchable in a direction substantially parallel and corresponding to the direction of the saturated free magnetizations.

Growing community of inventors

Seyssinet-Pariset, France

Ioan Lucian Prejbeanu