Simultaneous wafer-scale vacuum encapsulation and microstructure cladding with LPCVD polycrystalline 3C-SiC

This work reports a novel wafer-scale packaging method whereby MEMS devices are simultaneously vacuum sealed in a micromachined cavity and clad with a thin polycrystalline silicon carbide (poly-SiC) film. The deposition of poly-SiC is controlled by adjusting the precursor flow rates to yield a uniform film with low residual stress and moderate resistivity to prevent film cracking and device shorting. Functioning poly-SiC clad, silicon-core resonators are tested. Comparison of the resonator quality factor (Q) to a pressure-Q calibration curve determines the pressure within the sealed cavity to be 8 mBar.