Spin-Orbit Torque Magnetic Memory With Perpendicular Anisotropy
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Solution Overview
Problem
Magnetic memory technologies face challenges in achieving high integration density while maintaining magnetization stability and preventing data rewriting due to increased current requirements, which can lead to insulation breakdown and reduced integration rates.
Innovation Solution
A magnetic memory design incorporating spin-orbit torque type magnetoresistance effect elements with specific control elements and wiring configurations that reduce reversal current and increase integration density, allowing for efficient data storage and retrieval with minimized current leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If TMR elements are made more compact to achieve higher integration density, then integration density is improved, but magnetization stability decreases
Solution Approach 1:
The patent changes the magnetization orientation parameter from in-plane to perpendicular magnetization in the storage layer, which increases magnetic anisotropy energy and stabilizes magnetization even in compact structures. This parameter change allows achieving both high integration density and stable magnetization retention.
2Reliability
If ferromagnetic layer volume is increased to raise magnetization stability, then magnetization stability is improved, but element area increases reducing integration density
Solution Approach 1:
The patent introduces perpendicular magnetic anisotropy through interface engineering between the ferromagnetic layer and adjacent layers (such as Ru or Ta layers). This creates strong out-of-plane magnetization with high magnetic anisotropy energy, stabilizing magnetization without requiring increased layer volume, thus maintaining compact element area for high integration density.
3Ease of operation
If current density is increased to reverse magnetization by STT, then magnetization reversal is achieved, but thermal stability of the element decreases
Solution Approach 1:
The patent creates local quality differences by introducing specific interface structures (such as CoFeB/Ru/CoFeB sandwiches) with perpendicular magnetic anisotropy. These localized interface regions provide strong magnetization stability while allowing controlled magnetization reversal through spin transfer torque, achieving both operational capability and thermal stability.
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 proposed design effectively lowers reversal current and enhances integration density, enabling stable data storage and reduced reading errors, while maintaining efficient data processing and storage capabilities.
Implementation Method 1
A plurality of spin-orbit torque wiring lines 20 that extend in a second direction (x-direction) intersecting with a first direction (z-direction) which is a stacking direction of the magnetoresistance effect elements 10
Implementation Method 2
MRAM reads and writes data by utilizing the characteristic that when the relative orientation between the magnetizations of two ferromagnetic layers that sandwich an insulating layer is changed, the element resistance of the TMR element changes
Implementation Method 3
a method in which a magnetic field generated by an electric current is used to perform writing (magnetization reversal)
Data Source
AI summary
A magnetic memory including a plurality of magnetoresistance effect elements that hold information, each including a first ferromagnetic metal layer with a fixed magnetization direction, a second ferromagnetic metal layer with a varying magnetization direction, and a non-magnetic layer sandwiched between the first and second ferromagnetic metal layers; a plurality of first control elements that control reading of the information, wherein each of the plurality of first ferromagnetic metal layers is connected to a first control element; a plurality of spin-orbit torque wiring lines that extend in a second direction intersecting with a first direction which is a stacking direction of the magnetoresistance effect elements, wherein each of the second ferromagnetic metal layers is joined to one spin-orbit torque wiring line; a plurality of second control elements that control electric current flowing through the spin-orbit torque wiring lines.