Design and fabrication of an innovative three-axis Hall sensor

The measurement of all three components of a magnetic field, simultaneously to high precision with Hall sensors, remains a challenge. Given the high precision of state-of-the-art conventional uniaxial Hall sensors, this is disappointing. Currently, three-axis Hall sensors suffer from either, or a combination, of the following: large spatial distribution between active areas; high signal noise; cross-sensitivity between measurement axes due to angular errors or the planar Hall effect; the inability to measure at a single point in space and time. A new type of three-axis Hall sensor is proposed, consisting of three sets of uniaxial Hall sensors in a small active volume. The feasibility of the proposed sensor has been proven in a prototype with an active volume as small as 200 μm × 200 μm × 200 μm. Due to its unique configuration, the new sensor addresses current three-axis Hall sensor limitations: it provides a high spatial resolution of 30 μm × 30 μm × 1 μm for each field component; full field vector measurements practically at a single point in space and time; and a reduction of the planar Hall effect by a factor of 35. Angular errors between the individual Hall sensors in the prototype lie between 0.1° and 0.5°, above the tolerable error for non-corrected measurements. However, once understood they can be taken into account. With proper calibration, this type of three-axis Hall sensor has great potential for high-accuracy three-axis magnetic field measurements and is particularly suitable for field mapping of magnets.