Magnetic Sensor Magnetization via Annealing
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Solution Overview
Problem
Existing methods for producing magnetic sensors with different magnetization orientations on a single substrate are either complex due to the need for different materials with distinct annealing temperatures or impractical for large-scale industrial application, as they require successive deposition or local heating of zones.
Innovation Solution
A method involving the formation of anti-ferromagnetic and ferromagnetic layers on a substrate, followed by annealing at a temperature that aligns the magnetization of elongated blocks, allowing for the creation of blocks with fixed and orthogonal magnetization orientations using a magnetic field, which can be used to produce three-axis magnetic sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If successive deposition of zones with different magnetization orientations is used, then different magnetization directions can be achieved, but the manufacturing process becomes complex and requires different materials with distant annealing temperatures
Solution Approach 1:
The patent uses identical or similar ferromagnetic material layers for all magnetic zones that require different magnetization orientations. By depositing the same material stack uniformly across the substrate and then using selective annealing with magnetic field application, the method achieves different magnetization directions without requiring different materials for different zones, thereby simplifying the manufacturing process while maintaining precise magnetization control
Solution Approach 2:
The patent changes the parameters of the annealing process (temperature, magnetic field orientation, field strength) rather than changing the materials themselves. By varying these processing parameters during the annealing step, different magnetization orientations are achieved from the same material stack, reducing manufacturing complexity while maintaining the ability to precisely control magnetization directions
2Manufacturing precision
If local heating of zones is used to modify magnetization orientation, then magnetization directions can be changed, but the process becomes very long to implement when the number of magnetization zones is large
Solution Approach 1:
The patent merges multiple local annealing operations into a single global annealing process. Instead of heating and treating each magnetic zone separately (which would be time-consuming for large numbers of zones), the method applies a uniform annealing treatment across the entire substrate while using a magnetic field pattern to achieve the desired magnetization orientations in all zones simultaneously, thereby dramatically improving manufacturing productivity
Solution Approach 2:
The patent performs preliminary patterning of the magnetic zones before the annealing step, with the zones already defined in their geometric configurations. During the subsequent annealing process, pre-established magnetic field patterns guide the magnetization alignment without requiring real-time local control, enabling efficient processing of multiple zones in parallel and reducing overall manufacturing time
3Manufacturing precision
If different materials with distant annealing temperatures are used, then zones with different magnetization orientations can be produced, but the choice of materials is limited and manufacturing becomes complex
Solution Approach 1:
The patent employs the same ferromagnetic material composition for all magnetic zones that need different magnetization orientations. By using identical materials deposited in the same process stack, the method eliminates the need to select from limited material combinations with distant annealing temperatures, thereby improving ease of manufacture and material selection flexibility while maintaining precise control over magnetization directions through process parameter variation
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 method enables the efficient production of magnetic sensors with aligned magnetizations, facilitating the creation of three-axis magnetic sensors that can accurately measure magnetic fields along multiple axes, improving scalability and reducing manufacturing complexity.
Implementation Method 1
annealing of said blocks at a temperature above a temperature suitable for the anti-ferromagnetic material
Implementation Method 2
A non-ordered anti-ferromagnetic material does not exhibit exchange coupling after deposition on a ferromagnetic material
Implementation Method 3
Said adapted temperature corresponds to the ordering temperature of the anti-ferromagnetic material when the anti-ferromagnetic material is not magnetically ordered
Implementation Method 4
the application of a magnetic field oriented in a direction producing a second non-zero angle θ with said first main direction, the intensity of which is varied during annealing
Implementation Method 5
The application of the magnetic field can saturate the magnetization in each block and thus avoid the appearance of magnetic domains
Implementation Method 6
Said adapted temperature corresponds to the blocking temperature, that is to say the temperature beyond which there is no longer any exchange coupling between an anti-ferromagnetic material and a ferromagnetic material in contact
Implementation Method 7
Said adapted temperature can also correspond to the Néel temperature, that is to say the temperature above which the anti-ferromagnetic material becomes paramagnetic
Data Source
Figure 1A~1C
Figure 2~3B
Figure 4
AI summary
The invention relates to a method for making a device comprising magnetic blocks (111, 112, 113) resting on a substrate (100) and magnetized in different directions, comprising the steps of: a) forming, in a stack (108) of one or more layers (1041, 1042, 1043) of at least one antiferromagnetic material and one or more layers of at least one ferromagnetic material (1051, 1052) resting on a substrate, at least one first block and at least one second long, disjointed block extending respectively in a first principal direction and in a second principal direction, the first and second principal directions forming a first non-zero angle α between them; b) annealing said blocks at a temperature higher than the ordering temperature of said antiferromagnetic material or the blocking temperature or the Néel temperature of said material anti-ferromagnetic.