Magnetoresistive Element PMA Vortex Structure for Out-of-Plane Sensing
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Solution Overview
Problem
Existing magnetoresistive elements face challenges in achieving high out-of-plane sensitivity while maintaining a compact size and efficient fabrication, as thick sense layers complicate the manufacturing process and reduce element density.
Innovation Solution
Introduce perpendicular magnetic anisotropy (PMA) across the sense layer with a vortex configuration, using a ferromagnetic material and enhancing materials to achieve a sense magnetization between 300 and 1400 emu/cm³ and a perpendicular magnetic anisotropy field greater than 1 kOe, maintaining a sense layer thickness below 200 nm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sense layer thickness is increased to improve out-of-plane sensitivity, then the sensitivity is improved, but the fabrication process becomes more complex and element density decreases
Solution Approach 1:
The patent changes the magnetic anisotropy parameter by introducing perpendicular magnetic anisotropy (PMA) through specific material composition and interface engineering. This allows the sense layer to maintain high out-of-plane sensitivity with reduced thickness by altering the magnetic energy landscape rather than relying solely on geometric thickness
Solution Approach 2:
The patent employs composite material structures including CoFeB/MgO/CoFeB tunnel magnetoresistive elements with carefully engineered interfaces. The composite structure of different materials (CoFeB, MgO, Ta, Ru, Pt) with specific thicknesses and properties enables enhanced TMR ratio and controlled magnetic anisotropy, achieving high sensitivity without requiring thick sense layers
2Measurement precision
If the sense layer thickness is increased to improve out-of-plane sensitivity, then the sensitivity is improved, but the element density per sensor area decreases
Solution Approach 1:
By changing the magnetic anisotropy from in-plane to perpendicular through material engineering and interface effects, the patent enables high sensitivity in thinner layers, thereby increasing the number of elements that can be packed into a given sensor area
Solution Approach 2:
The patent transitions the magnetic moment orientation from the in-plane dimension to the out-of-plane dimension through PMA engineering. This dimensional change in magnetization orientation allows for thinner sense layers while maintaining sensitivity, thus enabling higher element density
3Measurement precision
If the sense layer thickness is increased to improve out-of-plane sensitivity, then the sensitivity is improved, but the fabrication process requires longer etch time and additional steps
Solution Approach 1:
The patent modifies the magnetic anisotropy parameter through interface engineering and material composition control, enabling high sensitivity in thinner layers that require shorter etch times and fewer fabrication steps
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 solution maintains high out-of-plane sensitivity without increasing the sense layer thickness, allowing for simpler fabrication and higher element density in magnetoresistive sensors.
Implementation Method 1
the magnetoresistive element is configured to measure an external magnetic field oriented substantially perpendicular to the plane of the sense layer through the tunnel magnetoresistance between the reference layer and the sense layer
Implementation Method 2
The sense magnetization comprises a vortex configuration stable under the presence of an external magnetic field, the sense magnetization being reversibly movable in a direction out-of-plane relative to the reference magnetization when the external magnetic field varies in a direction out-of-plane
Implementation Method 3
Introduce perpendicular magnetic anisotropy (PMA) across the sense layer of the magnetoresistive element possessing a vortex configuration
Data Source
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AI summary
The present disclosure concerns a magnetoresistive element comprising a reference layer (21) having a reference magnetization (210) oriented out-of-plane; a sense layer (23) having a sense magnetization (230) comprising a vortex configuration stable under the presence of an external magnetic field (60) and reversibly movable in a direction out-of-plane relative to the reference magnetization when the external magnetic field (60) varies in a direction out-of-plane; and a tunnel barrier layer (22) between the reference layer and the sense layer. The sense layer has a thickness smaller than 200 nm. The sense layer (23) comprises a ferromagnetic material configured such that the sense magnetization is between 300 and1400 emu/cm3 and such that the sense layer (23) has a perpendicular magnetic anisotropy field that is greater than 1 kOe (79.6×103 A/m). The present disclosure further concerns a magnetoresistive sensor comprising a plurality of the magnetoresistive element.