Moire interferometric alignment and overlay techniques

摘要

Moire alignment and overlay measurement techniques with nm-scale precision are demonstrated. Using 0.47-$mu@m pitch gratings, a 1-nm alignment resolution is demonstrated. A novel double-period moire grating is used to provide both coarse (approximately 10 $mu@m) and fine (approximately 1 $mu@m) capture ranges for integration with existing stage positioning systems. A new diffraction-order interferometry technique for nm-precision remote overlay readout, with potential application to latent image structures immediately after exposure, is demonstrated.