Capacitive Transducer for Accurate Displacement Control

Abstract

The underlying theory, design, and operation are presented for an interdigitated capacitive displacement transducer supported on an air-bearing stage. This device provides a purely electrical means of displacement measurement and offers the possibility of being closely matched to the substrate against thermal perturbations. Tests on a prototype system show the basic capacitive transducer to have a sensitivity of 2.6 mV/ μ m and a position uncertainty of 4 nm set by thermal noise. Copyright © 1981 by The Institute of Electrical and Electronics Engineers, Inc.