Shrinking design of a MEMS optical scanner having four torsion beams and arms

A design to reduce the chip size of a MEMS (microelectromechanical systems) optical scanner having four torsion beams and arms was investigated using both the simulation design and fabrication process, with the goal of increasing the total number of chips on a wafer. The scanner was composed of a 1.2-mm circular mirror and two pairs of torsion beams and arms that were fabricated using MEMS processing of a silicon-on-insulator (SOI) wafer based on our previous report.By using the sub-arm between the torsional beams and arms, the chip length could be decreased by approximately 10%, and the resonant frequency could be increased by approximately 0.5 kHz without decreasing the maximum deflection angle. Additionally, by using the backside silicon bonding process and removing one side of the outer frame, the chip length could be decreased by approximately 50%. These designed structures can increase the total number of MEMS chips by 10–50% on a wafer of the same size without degrading the scanner characteristics.