Calibration-based overlay sensing with minimal-footprint targets

• Main Authors: Wolterink, Tom A. W, Buijs, Robin D, Gerini, Giampiero, Verhagen, Ewold, Koenderink, A. Femius
• Format: Journal Article
• Language: English
• Published: 19-05-2021
• Subjects: Physics - Applied Physics
• DOI: 10.48550/arxiv.2106.09490

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 moir\'e patterns
to deterministically generate many overlay errors on a single chip, we
demonstrate successful 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 using
greater quantities of smaller overlay targets may benefit performance both
directly and through finer sampling of deformation.