A Vertical Deformation Mechanics Model for Proof-Mass in Micro-Machined SOI Comb Finger Accelerometers

For silicon direct bonding SOI accelerometers, due to the stress in device layer, there is vertical deformation in proof-mass, which can make the accelerometers fail to work. In the light of mechanics theory and by dividing the proof - mass into several continuous varied cross-section beams, utilizing symmetric continuous conditions of the beams, and combining deformation compatibility, a vertical deformation mechanics model of proof-mass is proposed. The validity of the model is demonstrated by measuring the experimental structures with SOI device layer 50 μm and oxide layer 5 μm. The model could hopefully be helpful in further exploration on deformation of MEMS structure.