Anomalous Hall Sensor With Ferromagnetic Layer For Linearity
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Solution Overview
Problem
Traditional Hall sensors face issues with high carrier concentration in metal materials leading to reduced output voltage and linearity, and in semiconductor materials, they require larger sizes and are sensitive to temperature changes, while existing GMR and TMR sensors have difficulties with magnetic field orientation and packaging.
Innovation Solution
A magnetic sensor utilizing the anomalous Hall effect with a multi-layered structure comprising a lower nonmagnetic metal layer, a ferromagnetic layer, and an upper nonmagnetic metal layer, where the ferromagnetic layer's thickness is less than 45 Å to ensure vertical magnetic anisotropy, and the nonmagnetic metal layers are of the same material, allowing for high linearity and sensitivity with a rhombic sensing region and integrated electrode and pad structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If metal materials are used in traditional Hall sensors, then the structure is simple and easy to manufacture, but the carrier concentration is high which reduces output voltage and linearity
Solution Approach 1:
The patent changes the material parameter from conventional metal to ferromagnetic alloy (CoFeB, CoFeSi, or CoFe), fundamentally altering the carrier concentration and magnetic properties to achieve both ease of manufacture and high linearity through anomalous Hall effect
Solution Approach 2:
The patent employs composite material structure with ferromagnetic layer (CoFeB/CoFeSi/CoFe) combined with nonmagnetic metal layers (Pt, Pd, or Ir), creating a multi-layered composite that leverages the anomalous Hall effect to resolve the contradiction between manufacturing ease and measurement precision
2Measurement precision
If semiconductor materials are used in Hall sensors, then the output voltage can be increased, but the sensor size must be increased and offset voltage occurs
Solution Approach 1:
The patent changes the material parameter from semiconductor to ferromagnetic metal, utilizing the anomalous Hall effect which provides high Hall voltage without requiring large sensor areas, thus resolving the contradiction between output voltage and sensor size
3Measurement precision
If semiconductor materials are used in Hall sensors, then the output voltage can be increased, but the distance between magnet and sensor must be very short causing characteristic distortion at high driving temperature
Solution Approach 1:
The patent changes the material parameter to ferromagnetic alloy with specific thickness (3-45 Å) to optimize the anomalous Hall effect, achieving high output voltage while maintaining temperature stability and eliminating the need for very short magnet-sensor distance
4Measurement precision
If GMR and TMR sensors are used, then magnetic field sensitivity can be improved, but the magnetic field orientation requirement and packaging difficulty arise
Solution Approach 1:
The patent changes the material parameter to ferromagnetic alloy with optimized thickness to achieve high magnetic field sensitivity through anomalous Hall effect, while the planar structure and standard fabrication processes reduce packaging complexity compared to three-dimensional GMR/TMR structures
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 solution provides a Hall sensor with high linearity, sensitivity, and temperature insensitivity, enabling flexible use environments by applying a magnetic field perpendicular to the interface, and simplifies the manufacturing process with a single etching step for the sensing, electrode, and pad regions.
Implementation Method 1
a ferromagnetic layer which is formed on the lower nonmagnetic metal layer and in which an anomalous Hall effect is generated by an applied magnetic field
Data Source
AI summary
Provided is a magnetic sensor using an anomalous Hall effect. Nonmagnetic metal layers are disposed on and below a ferromagnetic material so as to form a Hall voltage corresponding to a change in applied magnetic field. Linearity and saturation magnetization of the magnetic sensor depend on a thickness of the nonmagnetic metal layer and a thickness of the ferromagnetic material. In addition, provided is a Hall sensor using an anomalous Hall effect. Nonmagnetic metal layers are formed with respect to a ferromagnetic layer, and CoFeSiB constituting the ferromagnetic layer has a thickness ranging from 10 Å to 45 Å. A magnetic easy axis is formed in a direction perpendicular to an interface due to interface inducing action of the nonmagnetic metal layers. In addition, the Hall sensor includes a sensing region having a rhombic shape, an electrode line portion having a line shape, and a pad portion.