Dual TMR Element Structure with Conducting Layer
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Solution Overview
Problem
Magnetic tunnel junctions (MTJs) face challenges in stability and sensitivity to external magnetic fields due to differences in crystal symmetry between layers, leading to reduced reference layer stability and higher coercivity, which affects their performance in magnetic field sensing applications.
Innovation Solution
A dual tunnel magnetoresistance (TMR) element structure is developed with a conducting layer separating two TMR elements, each having a cobalt iron (CoFe) and tantalum layer stack, allowing for improved stability and sensitivity by decoupling crystal structures without breaking ferromagnetic coupling, and enabling a symmetrical response to magnetic fields through careful layer thickness and configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If MgO magnetic tunnel junctions are used to achieve high magneto-resistance ratio, then the magneto-resistance ratio is improved, but reference layer stability deteriorates and free layer anisotropy increases
Solution Approach 1:
The patent employs composite material structures including CoFeB/MgO/CoFeB tunnel magnetoresistance elements combined with specific pinning layers (CoFeB/Ru/CoFe) and capping layers (Ta, W, Mo). This composite structure achieves high TMR ratio while improving reference layer stability through the engineered multilayer configuration that addresses the inherent instability of MgO-based MTJs.
2Measurement precision
If MgO magnetic tunnel junctions are used to achieve high magneto-resistance ratio, then the magneto-resistance ratio is improved, but free layer coercivity increases
Solution Approach 1:
The patent applies local quality optimization by introducing specific layer compositions and thicknesses at critical interfaces. The CoFeB/Ru/CoFe pinning layer structure and the Ta/W/Mo capping layers provide localized magnetic anisotropy control and interfacial engineering that reduces free layer coercivity while preserving the high TMR ratio achieved through the MgO barrier.
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 dual TMR element structure enhances stability and sensitivity to magnetic fields, providing a more symmetrical and effective response, reducing coercivity and improving the operational range of magnetic field sensors.
Implementation Method 1
a conducting layer that is disposed between the first TMR element and the second TMR element and is in direct contact with the first TMR element and the second TMR element
Implementation Method 2
Magnesium oxide (MgO) magnetic tunnel junctions (MTJs) are widely used spintronics materials due to their high magneto-resistance ratio (MR %). The reason for this high ratio is due to the so-called coherent tunneling mechanism through the MgO barrier which filters in only highly-spin polarized electronic states.
Data Source
AI summary
In one aspect, a dual tunnel magnetoresistance (TMR) element structure includes a first TMR element and a second TMR element. The TMR element structure also includes a conducting layer that is disposed between the first TMR element and the second TMR element and is in direct contact with the first TMR element and the second TMR element.