Gold Single-Axis Differential Capacitive MEMS Accelerometer With Proof-Mass Position Control Electrode Fabricated by Post-CMOS Technology

This paper presents a gold single-axis differential capacitive MEMS accelerometer with a proof-mass position control electrode. The proposed device consists of the proof-mass position control electrode separating from the detection electrode to avoid feedback cross-talk. To realize the proposed device structure, the relationship between the control voltage and displacement with the single proof-mass is investigated regarding the MEMS accelerometer design for micro-g
$(1\mathrm{g}= 9.8\mathrm{m}/\mathrm{s}^{2})$
level sensing. The fabricated devices indicate that the displacement of 1.01
$\upmu \mathrm{m}$
can be obtained by a 3.0 V control voltage. Moreover, experimental results of the device characteristics show a sensitivity and Brownian noise
$B_{\mathrm{N}}$
of 1.18
$\text{pF}/\mathrm{G}$
and 341
$\text{nG}/\surd\text{Hz}$
, respectively. Evaluation results based on the measured data provided a total noise less than 10
$\upmu\mathrm{G}/\surd\text{Hz}$
, which is 3.64
$\upmu\mathrm{G}/\surd\text{Hz}$
, the target value to realize micro-g level sensing. In conclusion, these results confirm that the proposed device has a potential for establishing the high-performance CMOS-MEMS accelerometer by proof-mass position control.