CMOS-MEMS electrostatic micromotor based on FGMOS transduction by electromechanical modification of its coupling coefficient and low operating voltage

This work consists of a design and simulation of a structure composed by an aluminum structural layer whose purpose is to act as an angular electrostatic micromotor. The structure of the micromotor is defined using the layers available from a 0.5 μm CMOS technology used for integrated circuit fabrication. In this proposal, a digital circuit is configured for the generation of the three phases needed for proper operation of the micromotor. The phases and poles of the stator are biased in an alternating sequence, thus, when there is a potential difference between the misaligned poles of the rotor and stator, an electrostatic force is generated that causes the motor to advance one step. If this sequence is performed correctly and periodically, the rotor reaches a set speed in a clockwise direction. As a novel contribution to the presented design, an FGMOS transistor is used as an auxiliary element to measure the rotating speed of the micromotor and whose control gate is a structure mechanically coupled to the rotor. The elements of the system are proposed for being monolithically integrated: the rotation control circuit, the micromotor, and the speed sensor. This work also shows a static simulation and a time-dependent simulation that allows predicting the behavior over time and the torque generated by the micro-actuator.