Magnetoresistive Angle Sensor Fabrication Using Dual Néel Temperatures
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Solution Overview
Problem
Existing methods for fabricating magnetic field angle sensors, such as laser repinning processes, are costly, require precise temperature control, and face challenges in aligning individual sensing bridges, limiting the efficiency and cost-effectiveness of two- and three-dimensional angle sensor production.
Innovation Solution
A method involving the use of antiferromagnetic materials with different Néel temperatures to align magnetization directions without laser repinning, by heating and applying magnetic fields in specific directions to tune the magnetization orientations of MR elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If laser repinning process is used to align magnetization directions, then magnetization alignment is achieved, but manufacturing cost increases and process complexity increases
Solution Approach 1:
The patent changes the temperature parameter during magnetic field application. By heating the substrate to above the Néel temperature of the antiferromagnetic material and then cooling it while applying a magnetic field, the magnetization direction is pinned without requiring laser repinning. This parameter change (temperature control) simplifies the overall manufacturing process while achieving the same alignment effect.
Solution Approach 2:
The patent extracts and eliminates the laser repinning step from the manufacturing process. By using a different approach (thermal treatment combined with magnetic field application), the complex laser alignment process is removed entirely, reducing device complexity and manufacturing cost while maintaining magnetization alignment capability.
2Manufacturing precision
If laser repinning process is used to align magnetization directions, then magnetization alignment is achieved, but manufacturing cost increases
Solution Approach 1:
The patent replaces the expensive laser repinning process with a more economical thermal treatment approach. By using standard heating and cooling procedures combined with magnetic field application, the manufacturing cost is reduced while achieving the necessary magnetization alignment. The antiferromagnetic material's thermal properties are utilized to achieve alignment at lower cost.
Solution Approach 2:
The patent changes the approach from optical (laser) to thermal-magnetic parameter control. By utilizing the temperature-dependent magnetic properties of the antiferromagnetic material, specifically heating above and cooling below the Néel temperature, the process becomes more cost-effective while maintaining alignment precision.
3Adaptability or versatility
If different antiferromagnetic materials with different Néel temperatures are used, then multi-directional magnetization alignment is enabled, but material selection complexity increases
Solution Approach 1:
The patent segments the magnetic field application process into distinct temperature stages corresponding to different Néel temperatures. By heating to different temperature levels and applying magnetic fields at each stage, separate magnetization directions are established for different antiferromagnetic materials. This segmentation enables multi-directional alignment while managing material selection complexity through systematic process control.
Solution Approach 2:
The patent applies local quality by targeting specific antiferromagnetic materials with specific temperature treatments. Each material layer is treated according to its unique Néel temperature, allowing different magnetization directions to be established in different regions or layers of the sensor structure, enabling 2D or 3D angle sensing capability.
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 eliminates the need for costly laser repinning, improves temperature control, and enables efficient fabrication of two- and three-dimensional magnetic field angle sensors by aligning magnetization directions accurately and cost-effectively.
Implementation Method 1
heating, to a first temperature, a substrate... heating a first magnetoresistance (MR) element including a first type of antiferromagnetic material having a first Néel temperature... The first temperature is greater than the first Néel temperature
Implementation Method 2
The reference layer is generally comprised of a ferromagnetic (FM) layer/antiferromagnetic (AFM) layer system, where the FM layer is directly coupled to the AFM layer via an exchange interaction and is therefore said to be 'pinned'
Implementation Method 3
applying a first magnetic field to the substrate in an x-direction to enable the first magnetization direction and the second magnetization direction to be in the x-direction
Implementation Method 4
cooling the substrate to a temperature less than the first Néel temperature... enabling a temperature of the substrate to be a second temperature after ceasing to apply the first magnetic field... The second temperature is less than the first Néel temperature
Data Source
AI summary
In one aspect, manufacturing a magnetic-field angle sensor includes heating, to a first temperature, a substrate, which includes heating a first magnetoresistance (MR) element including a first type of antiferromagnetic material having a first Néel temperature and a first magnetization direction and heating a second MR element including a second type of antiferromagnetic material having a second Néel temperature and a second magnetization direction. The manufacturing also includes, after heating the substrate to the first temperature, applying a first magnetic field to the substrate in an x-direction to enable a first magnetization direction and a second magnetization direction to be in the x-direction, enabling a temperature of the substrate to be a second temperature and applying a second magnetic field to the substrate in a y-direction to enable the second magnetization direction to be in the y-direction while the first magnetization direction remains in the x-direction.