Magnetic Tunnel Junction Element with CoFeB Protective Layer
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Solution Overview
Problem
Existing magnetic tunnel junction (MTJ) elements face challenges in achieving sufficient thermal stability and tunnel magnetoresistance ratio, especially at smaller sizes, due to limitations in interface magnetic anisotropy, which affects data retention and performance in magnetic memory applications.
Innovation Solution
A magnetic tunnel junction element is designed with a specific layered structure including a reference layer, a barrier layer, a recording layer, and protective layers such as Pt, Ru, or CoFeB, which enhances interface magnetic anisotropy and thermal stability by maintaining the integrity of the MgO layer, allowing for smaller junction sizes while maintaining high thermal stability factors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the junction surface size is reduced to increase storage density, then the device size is improved, but the interface magnetic anisotropy becomes insufficient leading to degraded thermal stability
Solution Approach 1:
The patent changes the material composition parameter of the protective layer, specifically using CoFeB (cobalt-iron-boron alloy) with controlled thickness (0.5-2.0 nm) to optimize the interface magnetic anisotropy. This parameter change enables maintaining high thermal stability factor (Δ≥80) even at reduced junction sizes by enhancing the perpendicular magnetic anisotropy energy at the interface between the protective layer and magnetic layers.
Solution Approach 2:
The patent employs a composite protective layer structure combining CoFeB alloy with specific thickness control, creating a multi-functional layer that simultaneously provides oxidation protection and enhances interface magnetic anisotropy. The CoFeB composite structure at the interface between protective layer and magnetic layers generates the necessary perpendicular magnetic anisotropy to maintain thermal stability in miniaturized devices.
2Volume of moving object
If the junction surface size is reduced to increase storage density, then the device size is improved, but the tunnel magnetoresistance ratio becomes degraded
Solution Approach 1:
The patent optimizes the thickness parameter of the CoFeB protective layer (0.5-2.0 nm) to simultaneously maintain high TMR ratio and enable device miniaturization. This precise parameter control ensures that the interface magnetic anisotropy is sufficiently enhanced while preserving the tunnel magnetoresistance characteristics necessary for reliable readout signals in scaled-down MTJ elements.
3Device complexity
If a conventional protective layer structure is used, then the device complexity is low, but the interface magnetic anisotropy is insufficient for small junction sizes
Solution Approach 1:
The patent modifies the protective layer by incorporating CoFeB alloy with controlled thickness (0.5-2.0 nm), changing the material composition and dimensional parameters to enhance interface magnetic anisotropy. This parameter optimization provides sufficient perpendicular magnetic anisotropy energy density to maintain thermal stability factor Δ≥80 in miniaturized MTJ elements without significantly increasing structural complexity.
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 enhanced interface magnetic anisotropy achieved through this structure ensures a thermal stability factor of 80 or more, even at smaller junction sizes, improving the performance and data retention of magnetic memory devices.
Implementation Method 1
The performance of an MTJ element is represented by a tunnel magnetoresistance ratio TMR
Implementation Method 2
the interface magnetic anisotropy required for ensuring a thermal stability factor Δ=80 is increased by reducing the size of the junction surface
Data Source
AI summary
A magnetic tunnel junction element (10) includes a configuration in which a reference layer (14) that includes a ferromagnetic material, a barrier layer (15) that includes O, a recording layer (16) that includes a ferromagnetic material including Co or Fe, a first protective layer (17) that includes O, and a second protective layer (18) that includes at least one of Pt, Ru, Co, Fe, CoB, FeB, or CoFeB are layered.