Cantilever based MEMS for multiple mass sensing

A cantilever based micro electro mechanical system (MEMS) for mass detection is presented. The sensor for multiple detections is composed by several cantilevers in an array configuration integrated monolithically with CMOS. Cantilevers are excited electrostatically to its resonance frequency. The oscillation of the microcantilever is detected by a capacitive detection technique. Mass variation is detected by resonance frequency shifting. The mechanical transducers are fabricated after CMOS process on polysilicon, one of the CMOS layers. Optical lithography is used for the cantilevers definitions. Cantilevers of 50 /spl mu/m length, 1.1 /spl mu/m wide and 600 nm thick have been defined. This sensor provides a mass sensitivity of 70 ag/Hz.