A novel capacitive accelerometer with an eight-beam-mass structure by self-stop anisotropic etching of (1 0 0) silicon

This paper reports a novel capacitive sandwich accelerometer with an eight-beam-mass structure fabricated by self-stop anisotropic wet etching of (1 0 0) silicon and wafer-level Si-Si bonding. In this structure, eight straight beams symmetrically connect to the corners of the proof mass on both sides. These suspension beams are formed by self-stop anisotropic wet etching of (1 0 0) silicon, without heavy boron doping or Si-Si bonding. Through this beam-fabrication approach, the beam thickness can be well controlled and intrinsic stress in the beams is minimized. Accelerometers with different sensitivities can be easily fabricated by varying the thickness of the beams without making any change to the masks. For a device with 17 νm thick beams, the resonance frequency and the quality factor are 696 Hz and 47, respectively. The accelerometer has a sensitivity of 0.35 V g^-1.