Abstract This paper demonstrates a novel method to measure the pressure inside a MEMS thin-film package. It is based on an innovative use of the Focused Ion Beam (FIB) and Laser Doppler Vibrometer (LDV). LDV was used to measure the package cap resonance frequency. To determine the package internal pressure, the ambient pressure dependent cap resonance frequency was characterized firstly on the sealed package. After the first characterization, the sealed package was opened by FIB and the ambient pressure dependence of the resonance frequency was measured again. The intersection of the two measured curves provides the package internal pressure. The accuracy of the pressure determination for the specific application discussed in this paper is ∼1.5 mbar.
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