Ultralow-cost surface-micromachined tunneling sensor

Hughes Electronics has developed a novel surface micromachining process for fabricating extremely low cost integrated tunneling sensors for a wide variety of military and commercial applications. Previously fabricated bulk micromachined tunneling devices have demonstrated the high displacement sensitivity (approximately 4.0 X 10^-5 nm/(root)Hz at 500 Hz) obtainable with tunneling transduction. However, these early devices were fabricated with processes that yielded fairly large multi- wafer sensors which are difficult to integrate with the control electronics and package, thus limiting commercial development. This paper describes our surface micromachining techniques, their compatibility with large volume production, accelerometer device performance, and the system applications for this new technology.