Monolithic piezoresistive CMOS magnetic field sensors

Abstract

Two original electromechanical magnetic sensors have been developed using a fully industrial fabrication process that relies on bulk wet etching of CMOS dies. The first device uses the Lorentz force to actuate a U-shaped cantilever beam, while piezoresistive polysilicon gauges convert the beam bending into an electrical signal. A 2 μT sensor resolution is demonstrated, making this device suitable for earth magnetic field measurement. The second prospective device uses a ferromagnetic material deposited on top of a free standing mechanical frame. Such approach leads to the design of a passive sensor that does not require any electrical power for actuation. © 2003 Elsevier Science B.V. All rights reserved.