SYSTEM IN EXPOSURE SECTION OF LITHOGRAPHY TOOL, HOW TO REDUCE INTERFERENCE FROM UNDESIRABLE REFLECTION IN MEASURING INTERFERENCE ALIGNMENT WITH LITHOGRAPHY TOOL

摘要

PROBLEM TO BE SOLVED: To provide an optical locating method, especially, which effectively reduces and/or removes coherence with spurious or ghost reflection on measuring beam in an interferometer.;SOLUTION: Such an optical locating system as an interferometer is provided with a super luminescent device(SLD) (for example, laser diode having at least one anti-reflection coating surface) and a detector. This SLD forms light beam of short coherence length (for example, approx. 0.1-0.5 mm, shorter than light path length of an optical element and/or shorter than distance between each optical element). By using this short coherence length light beam, any interference effect from spurious or ghost reflection generated in normal locating can practically be reduced or removed.;COPYRIGHT: (C)2005,JPO&NCIPI