Patent ID: 7797985
Filing Date: 2010-09-21
Classification: G01B,G03F

Abstract:
1. An air gauge device for use in a lithography system, comprising: a reference probe configured to measure a surface of a reference surface and to generate a reference signal; a measuring probe configured to measure a surface of an object and to generate a gap error signal along a feedback path; a sensor configured to sense a position of the measuring probe and to generate a measuring probe movement signal; a motion machine to receive the measuring probe movement signal and the gap error signal to move the measuring probe; and a combiner configured to receive the measuring probe movement signal and the gap error signal and to generate a combination signal therefrom, wherein the desired distance between the measuring probe and the object is substantially maintained by adjusting the position of the measuring probe based on the measuring probe movement signal and the gap error signal and wherein a topography of the object is determined based at least on a comparison of the reference signal and the combination signal.