Two-axis silicon Hall effect magnetometer

Abstract

A novel single-chip sensing device for measurement of two orthogonal magnetic-field components using a common transducer zone and, for the first time, containing four contacts, is presented. On a rectangular n-type silicon substrate, n+-ohmic planar contacts are implemented − two of them are elongated and serve as power supply, and the other two terminals, positioned in the middle of the region between the elongated ones, function as outputs. A proper coupling arrangement is used for obtaining the information about vector components Bx (parallel to the supply contacts) and Bz (perpendicular to the substrate). Actually, the 2D magnetometer integrates an in-plane sensitivе Hall element and a device with vertical magnetic-field activation. The sensor operation is determined by the direction of the individual parts of the curvilinear current trajectory and the Lorentz force deflection action on them. The 2D vector sensor interface circuitry in hybrid realization comprises three instrumentation amplifiers and a differential amplifier. Simple fabrication technology is applied, containing four masks. The effective spatial resolution volume is high, constituting about 90×60×40μm3. The respective channel-magnetosensitivities without amplification reached: the lateral sensitivity Sx≈17V/AT and the vertical sensitivity Sz≈23.3V/AT. The channel cross-talk at induction B≤1.0T is no more than 3% and the lowest detected induction Bmin for the two-axis device at supply 3mA over frequency range f≤100Hz is about 11μT.