A CMOS-compatible bulk technology for the fabrication of magnetically actuated microbalances for chemical sensing

A resonant chemical sensor, fabricated in a standard, CMOS-compatible technology followed by a two-mask post-processing, is presented. A silicon dioxide plate, suspended to two torsional springs, is released from the silicon substrate by means of a TMAH anisotropic wet etch. Two metal loops are integrated on the plate. The first, in conjunction with an external micromagnet, is used to drive the plate into mechanical resonance, while the second loop is used for detection. In accordance with the microbalance principle, a shift of the resonance frequency can be related to the adsorption on the plate of the chemical species under test. The sensor design, and first results on the implementation of the post-processing technology, are presented.