Microfabrication and Characterization of SiO2 Microcantilever for High Sensitive Moisture Sensor

As an outstanding sensor platform, surface-stress sensing microcantilevers have potential application in moisture detection. To enlarge the deflection of the microcantilever under surface stress induced by specific reactions, a new SiO₂ microcantilever is developed which features a much lower Young's modulus than conventional Si or SiN_x microcantilevers. For comparing SiO₂ cantilever with Si cantilevers, simulation of the cantilever sensor is given, resulting in good agreement with the experimental data. To fabricate this device, a new fabrication process using isotropic combined with anisotropic dry etching to release the SiO₂ microcantilever beam by ICP (inductively coupled plasma) was developed and investigated. Attributed to the high sensitivity, significant deflection amplitude of the surface modified SiO₂ microcantilever was observed upon exposure to one percentage relative humidity.