Researchers have developed a 3-axis Hall-effect magnetic sensor based on a compact inverted pyramid structure, offering improved accuracy and reduced signal interference in magnetic field detection.
Study: Inverted pyramid 3-axis silicon Hall-effect magnetic sensor with offset cancellation. Image Credit: aslysun/Shutterstock.com
Detailed in a recent Microsystems & Nanoengineering article, the sensor combines microelectromechanical systems (MEMS) with complementary metal-oxide-semiconductor (CMOS) technology to push the performance boundaries of magnetic sensors used in automotive, industrial, and consumer electronics. These types of sensors are already critical in fields like automotive systems, industrial automation, and consumer electronics—but this design could help push their performance even further.
Background
Magnetic sensors play a vital role in technologies that require position sensing, motion tracking, and angle measurement. Hall-effect sensors, in particular, dominate this space thanks to their robust performance and compatibility with CMOS technology. They typically come in two types: vertical Hall devices (VHDs) and planar Hall devices (PHDs), each designed to detect magnetic fields in different planes.
Despite their strengths, traditional Hall-effect sensors face challenges in sensitivity and signal-to-noise ratio. To address these limitations, researchers have been exploring ways to enhance sensor performance while keeping device size and complexity in check.
Recent progress in MEMS and advanced geometries—like the inverted pyramid design featured in this study—offers promising solutions. These designs support three-dimensional magnetic field detection, improve offset calibration through current-spinning techniques, and reduce crosstalk. As demand grows for compact, high-performance sensors, innovations like this are key to improving accuracy and reliability in real-world applications.
The Current Study
The article outlines the sensor’s design and fabrication in detail. At its core is an inverted pyramid structure with four sloped faces, each functioning as an independent Hall element. These faces were formed using tetramethylammonium hydroxide (TMAH) etching and then doped with n-type materials to create active sensing regions. The slope angle of 54.74° was carefully selected to optimize the sensitivity of each element.
The fabrication process combined reactive ion etching (RIE) and wet etching to achieve the desired geometry while minimizing issues like lithographic misalignment. Phosphorus and arsenic were then implanted into the silicon to tune the electronic properties necessary for Hall sensing. A two-step passivation process was then applied at the end to shield the device from environmental damage, contributing to its durability and reliability.
Results and Discussion
Performance tests focused on key metrics such as sensitivity, offset, crosstalk, and noise power spectrum, using several first-generation prototypes. The researchers applied current-spinning techniques to significantly lower the offset—by one to three orders of magnitude—reducing the need for complex calibration during manufacturing.
Comparative data clearly illustrates the impact of this method, showing measurable improvements in overall sensor performance. Scanning electron microscope (SEM) and optical images provide visual confirmation of the device’s structural precision, further supporting the design’s robustness and manufacturability.
Conclusion
The inverted pyramid Hall-effect sensor introduces a notable improvement in magnetic sensing. Its innovative structure enhances measurement accuracy and effectively addresses challenges like offset correction in a scalable, CMOS-compatible format. The integration of MEMS and CMOS technologies also opens the door to commercial viability across industries that demand compact, reliable, and high-performance sensors.
The authors note that continued work is needed to fully align this sensor with standard CMOS platforms, which would streamline large-scale production and reduce costs. They also acknowledge the contributions of their research collaborators and funding partners, underscoring the collaborative effort behind this advancement.
This study lays important groundwork for the future of magnetic sensors—pointing toward a new generation of precise, efficient, and cost-effective solutions with widespread application potential.
Journal Reference
Ruggeri J., Ausserlechner U., et al. (2025). Inverted pyramid 3-axis silicon Hall-effect magnetic sensor with offset cancellation. Microsystems & Nanoengineering 11, 26. DOI: 10.1038/s41378-025-00876-9, https://www.nature.com/articles/s41378-025-00876-9