CoFeB Magnetic Memory Element with Perpendicular Anisotropy
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Solution Overview
Problem
Current magneto resistive effect elements in MRAMs face challenges in achieving high magnetoresistance ratio, low write current density, and high thermal stability, particularly when combining materials with perpendicular magnetic anisotropy and MgO, which often result in a trade-off between these characteristics.
Innovation Solution
The use of CoFe and CoFeB materials with specific film thickness control and annealing temperatures to orient magnetization perpendicular to the film plane, combined with a MgO barrier layer, allows for coherent tunneling conduction and high magnetoresistance ratios, while Heusler alloys further enhance spin polarizability and reduce write current density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If materials with perpendicular magnetic anisotropy are combined with MgO barrier layer, then magnetoresistance ratio is improved, but write current density increases
Solution Approach 1:
The patent changes the material composition parameters of the ferromagnetic layers, specifically using CoFeB with controlled thickness (1-3 nm) and boron concentration (20-40 at%), which modifies the magnetic anisotropy and spin polarization to reduce write current density while maintaining high magnetoresistance ratio
Solution Approach 2:
The patent employs composite material structures including CoFeB/CoFe multilayers with perpendicular magnetic anisotropy, combined with MgO barrier layers and Ta capping layers, creating a composite system that achieves both high magnetoresistance ratio and reduced write current density through synergistic material properties
2Measurement precision
If film thickness of ferromagnetic layers is reduced to enhance spin polarizability, then magnetoresistance ratio is improved, but thermal stability deteriorates
Solution Approach 1:
The patent optimizes the film thickness parameter of CoFeB to a specific range (1-3 nm) where quantum tunneling effects enhance spin polarization and magnetoresistance ratio, while the perpendicular magnetic anisotropy and controlled boron concentration provide sufficient thermal stability despite the thin film dimension
Solution Approach 2:
The patent introduces Ta capping layers and MgO barrier layers as intermediary materials that protect the thin CoFeB ferromagnetic layers, providing structural support and thermal stability while allowing the thin film configuration to maintain high spin polarizability and magnetoresistance ratio
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 enables the creation of magneto resistive effect elements with high magnetoresistance ratios and perpendicular magnetization, stabilizing the pinned layer during writing operations and maintaining thermal stability, thus addressing the limitations of existing technologies.
Implementation Method 1
combined with a MgO barrier layer, allows for coherent tunneling conduction and high magnetoresistance ratios
Implementation Method 2
the magnetization of the recording layer is anti-parallel to the magnetization of the pinned layer, and the bit information is '1'. When the current flows from the recording layer to the pinned layer, the magnetization of the recording layer is parallel to the magnetization of the pinned layer, and the bit information is '0'.
Implementation Method 3
The use of CoFe and CoFeB materials with specific film thickness control and annealing temperatures to orient magnetization perpendicular to the film plane
Data Source
AI summary
Provided are a magneto resistive effect element with a stable magnetization direction perpendicular to a film plane and with a controlled magnetoresistance ratio, and a magnetic memory using the magneto resistive effect element. Ferromagnetic layers of the magneto resistive effect element are formed from a ferromagnetic material containing at least one type of 3d transition metal such that the magnetoresistance ratio is controlled, and the film thickness of the ferromagnetic layers is controlled on an atomic layer level such that the magnetization direction is changed from a direction in the film plane to a direction perpendicular to the film plane.