An optical scanner based on cantilever-type electrostatic zipping actuators

Abstract

This paper discusses modeling, design, fabrication and characterization of an optical scanner based on cantilever-type electrostatic zipping actuators. The electrostatic actuator has been designed to achieve high displacements for large optical scanning angles at lower actuation voltages. The zipping actuators are fabricated using multi-layer polysilicon foundry fabrication processes. The electrostatic force between the cantilever and the bottom electrode on the substrate pulls the cantilever down. With a warped cantilever, the force closes the gap from the anchored end and gradually the zipping effect actuates the entire cantilever. In our design, mechanical structures are arranged to avoid electrical shortcircuit. With various annealing temperatures, the warped angles are controllable. The cantilever serves as a reflective surface and the high out-of-plane displacement is used to steer a reflected laser beam for imaging and scanning applications. In this paper we present the design considerations in electrostatic zipping actuator displacement and control as well as the arrangement for optical scanning.

An Optical Scanner Based on a Cantilever-Type Zipping Actuator

“…However, there is no insulation layer between the polysilicon layers due to the foundry fabrication procedures. A mechanical structure was designed on the cantilever to prevent a short circuit when the top electrode was pulled down to the bottom electrode (Rao et al 2007). Shown in Figure 2, six gaps along each edge of the bottom electrode layer allow the top cantilever electrode to land on the silicon nitride without touching the bottom electrode layer while the electrostatic forces can still be formed between the top and bottom electrodes.…”