Magnetic Sensor Pinning via Perpendicular Field and Soft-Magnetic Structuring
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Solution Overview
Problem
Existing methods for producing magnetoresistive sensor devices face challenges in achieving high-resolution, cost-effective, and miniaturized sensors with multiple pinning directions, leading to low accuracy and high manufacturing costs due to the need for complex line structures and additional process steps.
Innovation Solution
A method involving the use of a soft-magnetic structuring element on a chip substrate, where the ferromagnetic layers are magnetized by a pre-treatment magnetic field applied perpendicularly to the substrate, allowing for adjustable pinning directions and simultaneous pinning of multiple resistance elements, thereby simplifying the production process and increasing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If complex line structures and additional process steps are used to achieve multiple pinning directions, then manufacturing precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent applies a pre-treatment magnetic field perpendicular to the chip substrate surface (out-of-plane direction) instead of using complex in-plane line structures. This dimensional change simplifies the manufacturing process while achieving accurate pinning directions through the soft-magnetic structuring element's geometric design.
Solution Approach 2:
The patent changes the magnetic field application parameter from in-plane to perpendicular orientation, and uses temperature control (heating above blocking temperature) to enable reversible magnetization. These parameter changes allow simple structuring elements to achieve complex pinning patterns without additional process steps.
2Manufacturing precision
If complex line structures and additional process steps are used to achieve multiple pinning directions, then manufacturing precision is improved, but manufacturing cost increases
Solution Approach 1:
By switching to perpendicular magnetic field application, the patent eliminates the need for complex in-plane magnetic field generation structures, reducing manufacturing steps and costs while maintaining pinning accuracy through soft-magnetic element geometry.
Solution Approach 2:
The soft-magnetic structuring element acts as an intermediary that converts a simple perpendicular magnetic field into localized in-plane pinning fields at its boundaries. This intermediary approach simplifies the overall manufacturing process while achieving the desired pinning precision.
3Measurement precision
If miniaturization is pursued for high-resolution sensors, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The perpendicular magnetic field approach allows miniaturized sensors to be pinned accurately without requiring proportionally smaller complex in-plane structures. The soft-magnetic elements' geometric design maintains pinning effectiveness at reduced scales.
Solution Approach 2:
The soft-magnetic structuring element serves multiple functions: it guides the perpendicular magnetic field, creates localized pinning fields at its boundaries, and can be designed in various geometries to achieve different pinning directions, making it a universal solution for miniaturized multi-directional pinning.
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 enables the production of high-accuracy magnetic field sensors with adjustable pinning directions, reducing manufacturing costs and complexity, and allowing for 2D or 3D magnetic field measurement on a single chip substrate.
Implementation Method 1
which comprises at least one ferromagnetic layer and at least one antiferromagnetic layer, exchange coupling acting between the ferromagnetic and antiferromagnetic layers
Implementation Method 2
heating the resistive element above the blocking temperature of the material of the antiferromagnetic layer at which the exchange coupling between the antiferromagnetic layer and the ferromagnetic layer disappears
Implementation Method 3
the ferromagnetic layers are exposed to an external magnetic field, which forces them into a defined direction of magnetization
Implementation Method 4
cooling the resistive element below the blocking temperature
Data Source
Figure 1a~1b
Figure 2a~2c
Figure 3
AI summary
The invention relates to a method and an apparatus for permanently magnetizing at least one ferromagnetic layer in a magnetic sensor device (10) applied to a chip substrate (12). Said method comprises the steps of: - producing at least one resistive element (14) on a chip substrate (12); - applying at least one soft-magnetic patterning element (18) to the chip substrate (12); - heating the resistive element (14) to a temperature above the blocking temperature and applying a pretreating magnetic field (38); - cooling the resistive element (14) to a temperature below the blocking temperature; - eliminating the pretreating magnetic field (38). According to the invention, the soft-magnetic patterning element (18) is disposed in such a way that the applied pretreating magnetic field (38) penetrates the patterning element (18) substantially perpendicularly to the chip surface (36) and generates magnetic field components which extend parallel to the chip surface at the location of the resistive element (14) and which penetrate at least some portions of the ferromagnetic layer of the resistive element (14).