SOT-MRAM Conductive Layer Alloy Composition for Write Efficiency

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Spin-orbit torque magnetic random access memories (SOT-MRAMs) have inferior write efficiency compared to spin transfer torque magnetic random access memories (STT-MRAMs, with larger cell area and higher write current requirements, which limits their capacity and efficiency.

Innovation Solution

The use of conductive layers with specific alloys such as Ir-Ta, Ir-V, Au-V, Au-Nb, or Pt-V, having a face-centered cubic (fcc) structure, reduces the switching current and improves write efficiency by enhancing the voltage-assisted magnetic anisotropy control effect and spin Hall angle, thereby minimizing write current density and power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If SOT-MRAM structure is used to separate read and write current paths, then reliability is improved, but cell area increases to 12 F2

Engineering Contradiction:

Improvecurrent path separationVSAvoidcell area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent changes the material parameter of the conductive layer from conventional materials to specific alloys (Ir-Ta, Ir-V, Au-V, Au-Nb, Pt-V) with fcc structure, which have optimized spin Hall angles and magnetic anisotropy properties. This material parameter change enables reduced cell area while maintaining the SOT-MRAM reliability advantage through separate read/write current paths.

Inventive Principle:

Principle #35Parameter changes

2Use of energy by moving object

If SOT-MRAM is used to reduce write current, then power consumption decreases, but write efficiency remains low at 0.3

Engineering Contradiction:

Improvepower consumptionVSAvoidwrite efficiency

Core Design Contradiction:

Use of energy by moving objectVSProductivity

Solution Approach 1:

The patent optimizes the spin Hall angle parameter by selecting specific fcc-structured alloys, which directly improves write efficiency. The magnetic anisotropy parameter is also controlled through material selection and thickness optimization, enabling both low power consumption and high write efficiency to be achieved simultaneously.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite material structures, specifically alloy combinations like Ir-Ta, Ir-V, Au-V, Au-Nb, and Pt-V, which combine the advantages of different materials to achieve both low switching current and high write efficiency, resolving the contradiction between power consumption and write efficiency.

Inventive Principle:

Principle #40Composite materials

3Use of energy by moving object

If conductive layer thickness is reduced to minimize write current density, then switching current decreases, but spin Hall angle and magnetic anisotropy control effect deteriorate

Engineering Contradiction:

Improveswitching currentVSAvoidmagnetic anisotropy control

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent identifies optimal thickness parameters for each alloy material that balance switching current and magnetic anisotropy control. By changing the material composition parameter, the optimal thickness parameter shifts, allowing thin film structures to maintain both low switching current and strong magnetic anisotropy control through the voltage-assisted effect.

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach decreases the switching current and power consumption while improving write efficiency, allowing for higher density and faster write operations in SOT-MRAMs, thus bridging the gap with STT-MRAMs in terms of performance.

Implementation Method 1

The conductive layer includes at least one of an alloy including Ir and Ta, an alloy including Ir and V, an alloy including Au and V, an alloy including Au and Nb, or an alloy including Pt and V, each of the alloys having an fcc structure

Methodology Applied

Scientific EffectSpin Hall Effect: Hall Effect

Implementation Method 2

research and development of magnetic memories (magnetic random access memories (SOT-MRAMs)) that perform spin orbit torque (SOT) write operations has been actively performed

Methodology Applied

Scientific EffectSpin Orbit Torque:

Implementation Method 3

a voltage assisted magnetic anisotropy control technique, which changes the magnetic anisotropy (coercive force) of the storage layer by applying a voltage to the MTJ element

Methodology Applied

Scientific EffectVoltage-Assisted Magnetic Anisotropy Control:

Data Source

PatentUS10490736B2Magnetic memory

Publication Date: 2019.11.26 KK TOSHIBA

AI summary

A magnetic memory according to an embodiment includes: first to third terminals; a nonmagnetic conductive layer including first to third regions, the second region being disposed between the first and third regions, the first region being electrically connected to the first terminal, and the third region being electrically connected to the second terminal; and a magnetoresistive element disposed to correspond to the second region, including a first magnetic layer electrically connected to the third terminal, a second magnetic layer disposed between the first magnetic layer and the second region, and a nonmagnetic layer disposed between the first and second magnetic layers, the conductive layer including at least one of an alloy including Ir and Ta, an alloy including Ir and V, an alloy including Au and V, an alloy including Au and Nb, or an alloy including Pt and V, each of the alloys having an fcc structure.