Wednesday  |  Conference Center A  |  05:20 PM–05:40 PM

#13765, Temporal Drift in SiO2/Al Bimorph Actuators

Bimorph actuators are commonly used in the design and development of MEMS structures for a wide range of applications. However, the repeatability and reliability are two distinctive characteristics that all MEMS structures must adhere to such that degradation and hysteresis effects are minimized or eliminated from the design concept. In this research, we design, model, fabricate, and tested high, out-of-plane MEMS actuators constructed of aluminum and silicon dioxide. The design methodology capitalizes on the inherent residual stresses in bimorph structures in addition to the different coefficients of thermal expansions (CTE) to aid in the significant out-of-plane deflections necessary for surface micromachined large angle beamsteering applications. However, during experimental testing, it was observed the out-of-plane deflections changed over time such that repeatability and proper device functionality were compromised. In this paper, we will address these inherent changes, evaluate the various deposition of the SiO2 layer (sputtering, PECVD) and the use of silicon nitride as a capping and substitutional layer. We will provide experimental results from our updated deposition method and illustrate how silicon nitride layers integrated with an aluminum layer produces a repeatable and reliable bimorph actuator.

LaVern Starman   Air Force Research Laboratory
David Torres-Reyes   Air Force Research Laboratory
Harris Hall   Air Force Research Laboratory
Juan Pastrana   Michigan State University