Resonant Metal Cantilever with Attogram/Hz Mass Sensitivity Fully Integrated in a Standard 0.35- μm CMOS Process

This paper presents the design, fabrication and characterization of a high-sensitivity mass sensor based on a laterally resonating metal cantilever that is fully compatible with standard CMOS technologies, and which post-CMOS process is based on a single step wet etching process without the need of any additional lithographic process. The system uses electrostatic actuation and capacitive readout performed by a high-sensitivity readout circuitry monolithically integrated. The expected mass sensitivity of the metal resonators presented is around 1 ag/Hz and 4.5 ag/Hz for punctual mass and uniform mass deposition respectively. These sensitivities have been corroborated experimentally by means of two kinds of experiments: deposition of a punctual mass and deposition of a thin film of gold.