Calibration-based overlay sensing with minimal-footprint targets
article
Overlay measurements are a critical part of modern semiconductor fabrication, but overlay targets have not scaled down in the way devices have. In this work, we produce overlay targets with very small footprint, consisting of just a few scattering nanoparticles in two separate device layers. Using moiré patterns to deterministically generate many overlay errors on a single chip, we demonstrate readout of the relative displacement between the two layers and show that calibration on one realization of the targets can be used for overlay measurements on subsequent instances. Our results suggest that using greater quantities of smaller overlay targets may benefit performance both directly and through finer sampling of deformation.
Topics
TNO Identifier
959231
ISSN
00036951
Source
Applied Physics Letters, 119(11)
Publisher
American Institute of Physics AIP
Article nr.
111104
Collation
11 p.
Place of publication
College Park, MD, USA