High-G MEMS Accelerometer With Cross-Symmetric Structures

We present a piezoresistive high-G accelerometer that achieves 1% cross-axis sensitivity, 200 kG shock endurance, and 90% fabrication yield. The special features and advances in the accelerometer are as follows. First, the cross-symmetric structure of the accelerometer is effective in reducing cross-axis sensitivity. Second, the piezoresistors implanted on the elastic beam surface at a low doping level result in a high gauge factor and sensitivity with excellent shock endurance. Third, the cross-symmetric structure, generating both tensile and compressive stresses on the elastic beam surface, forms a piezoresistor bridge interconnection on a single side of the accelerometer, thus simplifying the fabrication process as well as the wiring and packaging process with a high yield of 90%. Experimental characteristics of the fabricated accelerometer show a detection range of up to 200 kG, a resonant frequency of 577.04 ± 13.62 kHz, a prime-axis sensitivity of 1.01
$\pm 0.11 ~\mu \text{V}$
/G, a cross-axis sensitivity ratio of 0.98% ± 0.62%, and a linearity of 99.99% ± 0.08% over the detection range. The fabricated accelerometer shows only a 1.35% variation of prime-axis sensitivities at 20 kG before and after a shock of 200 kG, indicating its performance stability and repeatability. Therefore, the accelerometer demonstrates strong potential for high-G impact monitoring applications in the fields of defense, aerospace, marine, automotive, construction, and so on.