Abstract
Recently, Micro-Electro-Mechanical Systems (MEMS) have been increasingly used in consumer electrical products, due to their progress in fabrication process and device design. Following the trend, the work further improves the process and design, which use single crystal silicon (SCS) wafers and deep etching process as the substrate and the primary step, respectively. The improvement mainly contains a release method, a fabrication platform and an actuator. In fabrication, MEMS structures are made of SCS wafers by using deep etching process. A new fabrication platform is proposed. Either structure thickness or trench depth significantly increases, even as large as the wafer thickness. The process is significantly simplified. By using low resistance SCS wafers, electrical current freely flow through the MEMS structures, makes MEMS devices are easier integrated vertically. The foregoing features increase the feasibility of three-dimensional-MEMS. To verify the fabrication platform, a comb-drive actuator was fabricated. In device development, a new actuation mechanism is proposed to actuate comb-drive actuators. An asymmetric configuration of the finger overlap was used to generate capacitive coupling for the actuation mechanism. When the driving voltages were applied on the stators, a voltage would be induced at the rotor due to the capacitive coupling. Then, an electrostatic force would be exerted onto the rotor due to the voltage differences between the stators and the rotor. The actuator’s static displacement and resonant frequency were theoretically analyzed. The experimental results verified the theoretical analysis. Using this method, the rotor can be fully insulated, i.e. the comb-drive actuators containing heterogeneous structures (e.g. flexible and insulating folded beams) become more practical and promising to provide an impact to MEMS technology.