Multi-Direction Exchange Pinning via Patterned Hard Magnetic Layers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for creating magnetic field angle sensors using GMR or MTJ devices struggle to simultaneously apply exchange pinning fields in multiple directions on the same substrate, leading to inaccurate and costly sensor fabrication, as applying a second pinning field often alters the direction of the first, requiring complex and expensive assembly processes.
Innovation Solution
A method involving the deposition of a hard magnetic layer on GMR or MTJ devices, which is shaped to direct magnetic flux in desired directions and then magnetized, allowing for simultaneous pinning of multiple layers in different directions through a single thermal annealing process without external fields, enabling the creation of 360-degree magnetic field angle sensors with anti-parallel and orthogonal pinning directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a second thermal annealing field is applied to create exchange pinning in a different direction on a second reference ferromagnetic layer, then the second layer can be pinned in the desired direction, but the direction of the first exchange pinning field on the first reference ferromagnetic layer changes
Solution Approach 1:
The invention divides the substrate into multiple regions, each with its own local magnetic field generation structure (such as patterned magnetizable layers or shield structures). This segmentation allows each region to be independently magnetized in different directions during a single thermal annealing process, preventing cross-interference between different pinning directions while achieving multi-directional exchange pinning on the same substrate
Solution Approach 2:
The invention applies local magnetic field generation structures (such as patterned hard magnetic layers, magnetizable layers with specific geometries, or shield structures) to different regions of the substrate. Each local structure is designed to generate a magnetic field in a specific direction, enabling precise control of pinning field directions in different locations without affecting other regions
2Manufacturing precision
If multiple reference layers are pinned in different directions using separate thermal annealing processes, then each layer can achieve correct pinning direction, but the fabrication process becomes complex and costly
Solution Approach 1:
The invention combines multiple pinning operations into a single thermal annealing process by introducing local magnetic field generation structures before the annealing step. These structures (such as patterned magnetizable layers or shield structures) remain in place during annealing to guide the magnetic field direction for each region simultaneously, eliminating the need for multiple separate annealing processes and reducing fabrication complexity
Solution Approach 2:
The invention introduces intermediary local magnetic field generation structures (such as patterned hard magnetic layers, magnetizable layers, or shield structures) that act as mediators during the thermal annealing process. These intermediaries generate and guide the magnetic fields in specific directions for different regions, enabling multi-directional pinning to be achieved through a single annealing step rather than multiple separate processes
3Manufacturing precision
If individual sensing islands are cut out, magnetized, rotated, and assembled to achieve different pinning directions, then the correct pinning orientations can be achieved, but assembly errors increase and production cost rises
Solution Approach 1:
The invention performs preliminary magnetization of all reference layers during a single thermal annealing process while they are still attached to the substrate in their final positions. Local magnetic field generation structures are used to establish the correct pinning directions for each region before the layers are finalized, eliminating the need for subsequent cutting, rotation, and assembly operations that could introduce errors
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 allows for the accurate and cost-effective fabrication of GMR or MTJ-based magnetic field angle sensors with full 360-degree measurement capability, reducing assembly errors and increasing sensor sensitivity by setting pinning directions in a single substrate process.
Implementation Method 1
exposure to a strong magnetic field
Implementation Method 2
thermal annealing process
Implementation Method 3
an anti-ferromagnetic material (AFM) layer deposited directly underneath or on top of a soft ferromagnetic material layer is utilize to generate an exchange pinning field on the soft ferromagnetic layer through a thermal annealing process
Data Source
AI summary
Simultaneous setting of exchange pinning field magnetization in more than one direction for several thin film structures on a single substrate has been achieved by first orienting the structures as needed. A layer of hard magnetic material is then deposited, suitably patterned to control the direction of its flux, and then magnetized through a single exposure to a strong magnetic field. The assemblage is then thermally annealed (in the absence of any applied field) at a temperature higher than the AFM material blocking temperature, following which the thin film structures are magnetically pinned in the intended directions.