Fabrication of Wafer-Level Vacuum Packaged Poly-SI/SiC Beam Resonators with Strain Sensitivity Larger than 1 kHz/με

We report about resonant strain sensors manufactured with a new fabrication technology based on composite polycrystalline silicon/3C-SiC double clamped beam resonators. The resonators are designed in such a way that the overall residual stress of the beam is decreased compared to the case of an all-SiC resonator. This increases the strain sensitivity of the beams and decreases their resonance frequency. Different design geometries of these resonators are investigated, yielding a maximum strain sensitivity of more than 1 kHz/με, which is more than three times larger than the present state of the art of resonant MEMS strain sensors.