Flexible stop and double-cascaded stop to improve shock reliability of MEMS accelerometer

• We model the shock response and contact mechanism of MEMS accelerometer with stop.
• Guidelines are presented for designing flexible stop and double-cascaded stop.
• MEMS accelerometers with flexible stop and with double-cascaded stop are fabricated.
• Shock tests using HPB are performed and typical failure modes are investigated.
• Experiments show corresponding results with simulation analysis.

Flexible stop could provide shock protection for MEMS accelerometer. By modeling and simulation, the paper studied the response of a closed-loop MEMS accelerometer with stop under shock of different amplitudes and pulse width. Contact force plays an important role and the shock response shows strong nonlinearity due to the contact mechanism. A kind of double-cascaded stop is proposed to mitigate high-frequency shock failure. MEMS accelerometers with flexible stop and with double-cascaded stop are both designed and fabricated based on SOG (silicon on glass) technology. Compared with shock tests of accelerometers with hard cylinder stop, flexible stop could withstand more than 1e4 g shock with about 100 μs pulse width. Double-cascaded stop is more robust to high frequency shock.