Vertical SOT-MRAM Stack for Spin-Orbit Torque and Thermal Stability
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Solution Overview
Problem
SOT-MRAM devices have not been demonstrated as a product due to the difficulty in finding suitable materials that exhibit high spin orbit torque, thermal stability, and suitable resistivity.
Innovation Solution
A magnetic memory device with a spin-orbit interaction active core having layers stacked in a longitudinal direction and a magnetic junction, utilizing materials like titanium nitride, perovskite oxides, and heavy metals to achieve desired resistivity and spin-orbit torque efficiency, with a method of manufacturing involving atomic layer deposition to form the core and junction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If suitable materials are selected for SOT generation, then spin orbit torque efficiency is improved, but finding materials that simultaneously exhibit high spin orbit torque, thermal stability, and suitable resistivity remains difficult
Solution Approach 1:
The patent employs composite material structures including heavy metal layers (Pt, Ta, W) combined with topological insulator layers (Bi2Se3, (BixSb1-x)2Te3), and perovskite oxide layers (LaAlO3, SrTiO3) to achieve high spin orbit torque efficiency while maintaining thermal stability and suitable resistivity. These composite structures allow optimization of individual material properties to collectively satisfy all three requirements simultaneously.
Solution Approach 2:
The patent applies local quality by creating vertically stratified material layers with distinct functions: heavy metal layers for spin-orbit coupling, topological insulator layers for high mobility and thermal stability, and perovskite oxide layers for interface engineering. Each layer is optimized locally for its specific function while contributing to the overall device performance.
2Reliability
If a multilayered structure is used to improve SOT efficiency through electric scattering, then device performance is enhanced, but device complexity increases
Solution Approach 1:
The patent transitions from planar two-dimensional material structures to vertically stacked three-dimensional multilayered structures. This dimensional change enables electric scattering in the perpendicular direction, significantly enhancing spin orbit torque efficiency. The vertical stacking allows for optimized transport pathways and improved SOT efficiency by exploiting out-of-plane scattering mechanisms that are unavailable in planar geometries.
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
The multilayered structure improves SOT efficiency by enabling electric scattering in a perpendicular direction, enhancing the device's performance and stability.
Implementation Method 1
spin-orbit interaction active core having a number of layers stacked in a longitudinal direction
Implementation Method 2
The multilayered structure improves SOT efficiency by enabling electric scattering in a perpendicular direction
Implementation Method 3
forming the magnetic junction around the portion of the spin-orbit interaction active core including depositing, by atomic layer deposition, the free layer, the tunnel barrier layer on the free layer, and the reference layer on the tunnel barrier layer
Data Source
AI summary
A magnetic memory device includes a spin-orbit interaction active core having a number of layers stacked along a longitudinal axis and a magnetic junction extending around the longitudinal axis and substantially surrounding at least a portion of the spin-orbit interaction active core. The magnetic junction includes a free layer, a reference layer, and a tunnel barrier layer between the free layer and the reference layer.