Hall Sensor Trench Ferromagnetic Concentrator Vertical Field Sensitivity
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Solution Overview
Problem
Current Hall-effect sensors are limited in sensitivity to vertical magnetic field components, resulting in a significant difference in sensitivity between horizontal and vertical magnetic field detection, making them less effective for three-dimensional magnetic field measurements.
Innovation Solution
The integration of a trench structure with ferromagnetic regions in a semiconductor chip, where the trench has vertical walls covered with soft ferromagnetic material, acts as a concentrator to amplify vertical magnetic field components, enhancing sensitivity by concentrating the magnetic field lines on the Hall cell.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a standard Hall-effect sensor is used, then the sensor can detect horizontal magnetic fields, but the sensitivity to vertical magnetic field components is limited
Solution Approach 1:
The patent introduces a vertical dimension by creating trenches that extend perpendicularly from the chip surface into the substrate. These vertical trenches with ferromagnetic coatings transform the sensor's capability from primarily horizontal field detection to including enhanced vertical field detection, achieving uniform sensitivity across all three spatial axes.
Solution Approach 2:
The ferromagnetic material coating the trench walls acts as an intermediary that concentrates and guides magnetic field lines. This intermediary structure enhances the coupling between vertical magnetic fields and the Hall cell, thereby improving sensitivity to vertical field components while maintaining horizontal detection capability.
2Measurement precision
If ferromagnetic regions are integrated into the sensor structure, then sensitivity to vertical fields is amplified, but the device complexity increases
Solution Approach 1:
The sensor structure is segmented into distinct functional regions: the Hall cell, the trench structure, and the ferromagnetic coating. This segmentation allows each component to be optimized independently and integrated through standard CMOS-compatible processes, managing complexity through modular design.
Solution Approach 2:
The patent modifies physical parameters such as trench depth, width, and ferromagnetic layer thickness to optimize vertical field sensitivity. By carefully controlling these parameters within standard manufacturing capabilities, the sensor achieves enhanced performance without requiring fundamentally new fabrication techniques.
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 significantly increases the sensitivity to vertical magnetic fields, allowing for a more uniform sensitivity across all axes, reducing noise and offset variability, and enabling the creation of triaxial magnetic sensors with comparable sensitivity in all directions.
Implementation Method 1
At least a portion of the outer surface of the vertical walls is covered with a layer of soft ferromagnetic material
Implementation Method 2
acts as a concentrator to amplify vertical magnetic field components, enhancing sensitivity by concentrating the magnetic field lines on the Hall cell
Implementation Method 3
a substrate of semiconductor material accommodates a Hall cell, the sensitivity whereof has been increased in the direction perpendicular to the main face
Data Source
AI summary
An integrated magnetic sensor formed in a body including a substrate of semiconductor material, which integrates a Hall cell. A trench is formed in the body, for example, on the back of the substrate, and is delimited by lateral surface portions that extend in a direction transverse to the main face of the body. The trench has a depth in a direction perpendicular to the main face that is much greater than its width in a direction parallel to the main face of the body, between the lateral surface portions. A concentrator made of ferromagnetic material is formed within the trench and is constituted by two ferromagnetic regions, which are set at a distance apart from one another and extend along the lateral surface portions of the trench towards the first Hall cell.