Super-accurate positioning technique using diffracted moire signals

Abstract

This paper deals with an autoiatic and precision alignient technique for proxiiity printing in x-ray lithography, using two pairs of iioire gratings, with moire signals from each pair being 180 out of phase with each other. The automatic and precision alignment experimental system which was constructed can measure both transmission moire signals and reflection moire signals at the same time. The automatic alignment was achieved using diffracted moire signals in transmission and also in reflection as control signals for a stage driver. The alignient position of the system was monitored by the difference signal in non-control signals. The drift characteristics of the alignment position were measured by operating voltage gain and/or offset voltage value of preamplifiers in the system. We concluded that the technique using diffracted moire signals is a usable automatic and precision alignment technique and the technique could be applied to one of the variable positioning techniques.