Versatile trench isolation technology for the fabrication of microactuators

A trench isolation technology employs trenches refilled with dielectric material to create, in a single layer, electrical isolation between mechanically joined components. This paper explores further use of this technology for MEMS fabrication, particularly the fabrication of electrostatic microactuators. Adding extra features to a two-mask trench isolation process new design opportunities, like isolation structures and isolation bumps, are created. The isolation structures can be employed as flexible or rigid connections between movable or fixed components or can serve to prevent the short-circuiting by maintaining the end distance between movable electrodes. The isolation bumps reduce stiction during release and operation, prevent short-circuiting due to an out-of-plane displacement and can serve as etch holes at the same time. The trench isolation technology is used to improve fabrication process of an actuator consisting of a large number of elastic electrodes connected in parallel and in series and to develop a novel low volume, large force (> 1 mN) and nanometer resolution electrostatic actuator for low displacement applications.