Magnetic Sensor Multilayer Films for Stable Detection Sensitivity
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Solution Overview
Problem
Multilayer ferromagnetic films in existing magnetic sensors often fail to achieve sufficient detection sensitivity and can cause variations due to differences in magnetic materials and film formation methods.
Innovation Solution
A magnetic sensor design with a multilayer structure featuring lower magnetic films made of high permeability material and upper magnetic films with larger separation widths, formed using sputtering and electrolytic plating methods, to enhance magnetic flux application and reduce magnetic resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a multilayer structure of ferromagnetic film is used, then the detection sensitivity can be improved, but variations in detection sensitivity occur depending on magnetic material or film formation method
Solution Approach 1:
The ferromagnetic film is divided into two distinct layers: a lower magnetic film and an upper magnetic film. Each layer serves a specific function - the lower layer with high permeability material collects and guides magnetic flux, while the upper layer provides magnetic coupling. This segmentation allows optimization of each layer's properties independently, reducing variations caused by material or process differences.
Solution Approach 2:
The patent employs composite material structure by combining different magnetic materials in the lower and upper magnetic films. The lower magnetic film uses high permeability material (such as Ni-Fe alloy) for efficient magnetic flux collection, while the upper magnetic film uses different material properties for optimal coupling. This composite approach enables tailored magnetic characteristics that improve detection sensitivity while minimizing variations.
2Measurement precision
If direct contact between lower magnetic film and upper magnetic film is implemented, then magnetic resistance is reduced, but manufacturing complexity increases
Solution Approach 1:
The lower magnetic film and upper magnetic film are directly contacted without intermediate layers, merging the two magnetic layers into a continuous magnetic path. This direct contact eliminates additional interfaces that would increase magnetic resistance, thereby improving detection sensitivity while keeping the structure relatively simple.
Solution Approach 2:
The patent removes unnecessary intermediate layers or buffer films that might be present in conventional multilayer structures. By extracting these non-essential components, the design achieves direct contact between magnetic films, reducing magnetic resistance and simplifying the manufacturing process.
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
The design achieves high detection sensitivity and reduces variations in sensitivity by efficiently applying magnetic flux to magnetosensitive elements while maintaining product reliability and avoiding characteristic degradation.
Implementation Method 1
magnetic flux is efficiently applied to the magnetosensitive element
Implementation Method 2
The material of the lower magnetic film is higher in permeability than the material of the upper magnetic film
Implementation Method 3
a second step of forming lower magnetic films of respective first and second ferromagnetic films on the insulating film using a sputtering method
Implementation Method 4
a third step of forming upper magnetic films of the respective first and second ferromagnetic films on the lower magnetic films of the respective first and second ferromagnetic films by electrolytic plating
Data Source
AI summary
A sensor chip of a magnetic sensor includes a magnetosensitive element, ferromagnetic films forming a magnetic gap overlapping the magnetosensitive element, and a passivation film provided on the ferromagnetic films so as to be filled in the magnetic gap. The ferromagnetic films each include a lower magnetic film and an upper magnetic film. The magnetic gap is configured such that a width between the upper magnetic films is larger than a width between the lower magnetic films. The material of the lower magnetic film is higher in permeability than the material of the upper magnetic film. With the above configuration, magnetic flux is efficiently applied to the magnetosensitive element, making it possible to achieve high detection sensitivity.