Magnetic Sensor Magnetization Pinned Layer Segmentation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing magnetic sensors face challenges in achieving a compact configuration with superior detection performance and high manufacturability, as they often have complex and cumbersome manufacturing processes that are not productive, especially when using giant magnetoresistive elements (GMR elements) in Wheatstone bridge circuits.
Innovation Solution
A magnetic sensor design featuring first and second magnetoresistive elements with specific antiferromagnetic layer structures and nonmagnetic spacing layers, where the magnetization pinned layers are formed with alternating ferromagnetic layers and nonmagnetic coupling layers, allowing for antiferromagnetic coupling and orientation pinning, and a simplified manufacturing method involving thermal annealing under a magnetic field to secure predetermined magnetization orientations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GMR elements are used in Wheatstone bridge circuits to improve detection sensitivity and response property, then the manufacturing process becomes complex and cumbersome
Solution Approach 1:
The magnetization pinned layer is segmented into multiple ferromagnetic layers (first through fifth ferromagnetic layers) with different thicknesses and magnetization directions. This segmentation allows each layer to contribute differently to the overall magnetic response, enabling precise control of detection characteristics while simplifying the manufacturing process through standardized layer deposition
Solution Approach 2:
Different regions of the magnetization pinned layer are assigned different local qualities through varying ferromagnetic layer thicknesses. The first and second ferromagnetic layers have different thicknesses from the third and fourth layers, creating localized magnetic properties that optimize both detection sensitivity and manufacturing simplicity
2Manufacturing precision
If separate annealing processes are performed for each GMR element to secure proper magnetization orientation, then manufacturing productivity decreases
Solution Approach 1:
Multiple annealing processes are merged into a single unified annealing step. The patent describes performing one annealing process that simultaneously secures the magnetization orientations of all ferromagnetic layers (first through fifth layers) in the magnetization pinned layer, eliminating the need for separate annealing operations for each layer or element
Solution Approach 2:
The single annealing process serves multiple functions: it orients the magnetization of the first ferromagnetic layer, the second ferromagnetic layer, the third ferromagnetic layer, and the fourth ferromagnetic layer simultaneously. This multi-functional approach maintains precise magnetization orientation while significantly improving manufacturing productivity
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 design enables a compact and highly sensitive magnetic field detection with improved linearity and high-frequency response, while simplifying the manufacturing process and eliminating the need for specialized facilities like laser or electron beam irradiation systems.
Implementation Method 1
a magnetization pinned layer having one or more first layers of a first group of ferromagnetic layers, and one or more second layers of a second group of ferromagnetic layers, the first layer and the second layer being stacked alternately with a nonmagnetic coupling layer in between, and being so antiferromagnetically coupled to each other as to have magnetizations which are opposite in direction to each other
Implementation Method 2
an antiferromagnetic layer pinning orientation of magnetization in the one or more first layers and orientation of magnetization in the one or more second layers
Implementation Method 3
a magnetization free layer in which orientation of magnetization changes in response to a signal magnetic field
Implementation Method 4
heating the first magnetoresistive element and the second magnetoresistive element while applying thereto a magnetic field in one given direction, thereby allowing orientation of magnetization in all of the plurality of ferromagnetic layers of the magnetization pinned layers in the first magnetoresistive element and the second magnetoresistive element to be secured by one operation
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A magnetic sensor includes: a first and a second magnetoresistive elements each including: a magnetization free layer; a nonmagnetic spacing layer; a magnetization pinned layer having one or more first layers of a first group of ferromagnetic layers and one or more second layers of a second group of ferromagnetic layers, in which the first layer and the second layer are stacked alternately with a nonmagnetic coupling layer in between, and so antiferromagnetically coupled to each other as to have opposite magnetizations to each other; and an antiferromagnetic layer pinning magnetization orientation in the one or more first and the second layers. The first layers in the first magnetoresistive element are one more in number than that of the one or more second layers. The number of the one or more first layers and that of the one or more second layers in the second magnetoresistive element are equal.