PHASE MEASUREMENT USING AERIAL IMAGE MEASURING TOOL

摘要

PROBLEM TO BE SOLVED: To ensure a direct measurement of phase shift generating in a phase shift area of a phase shift mask by measuring a relative shift between interference patterns caused by a first slit pair having the same phase shift characteristic and a second slit pair having a different phase shift characteristic. SOLUTION: A mask 55 contains a reference slit pair, each of which has substantially the same phase characteristic. The mask 55 has also a measuring slit pair, each of which has a different phase shift characteristic. An objective lens projects Young's interference stripes generated by the slit pairs on a plane of a NA aperture 90. A people image lens 69 projects these stripes on a CCD camera 71. A phase difference between the two slits of the measuring slit pair by measuring a relative fringe shift between the measuring slit pair and the reference slit pair.