Nonlinear micromachined flexure for stiction reduction

This paper reports the nonlinear micromachined flexure to reduce the stiction in MicroElectroMechanical Systems (MEMS). Good electrical contacts are essential in the applications like MEMS switches or relays. In this case high contact forces are required for reliable fully-metallic contacts. However the forces can also cause frequent stction failures. The proposed micromachined flexure shows highly nonlinear mechanical stiffness induced by a dimple under it. The parallel-plate actuator with the proposed flexures shows higher restoring forces to reduce the stiction failure without the increase of pull-in voltage. An analytical model that describes the deflection of the flexure is developed and verified using Finite Element Analysis (FEA). Finally the flexure is fabricated with general surface micromachining processes.