Metrological gratings and moire fringe detection methods for displacement transducers

摘要

Conventional methods of generating master grating patterns and replica gratings are described and the use of silicon as a substrate for metrological gratings is introduced. Optical displacement transducers based on a relative movement of a scale grating and an index grating are reviewed. The detection of misalignment between mask pattern and wafer in the fabrication of microcircuits is introduced as an important application.