A new sense element technology for accelerometer subsystems

Abstract

The author describes a capacitive accelerometer technology using sense element structures fabricated on the surface of a substrate or wafer. The sense element consists of an asymmetrically shaped flat plate of metal supported above a substrate surface by two torsion bars mounted on a central pedestal. The sense element is free to rotate around the torsion bars. Capacitor plates located on the substrate surface are used to detect the rotation. Fabrication of sense elements is done by selective electroforming in which a metal is electroplated onto a conductive substrate through a patterned photoresist layer. To produce suspended sense elements, the sense elements are fabricated partially on the top of a sacrificial spacer material deposited earlier. After the sense elements have been formed, the spacer material is then selectively etched, leaving the sense element supported only where it was formed directly on the substrate surface.<>