Overlay detection for multiple nanoimprint lithography in optical microscopic fields of view using Mie resonator arrays

This study proposes what we believe to be a novel method for detecting overlay accuracy in multiple ultraviolet nanoimprint lithography (UV-NIL) patterning using Mie resonances of silicon nanodisk (Si-ND) arrays. Overlay differences were quantified by analyzing the optical spectra of the Si-ND arrays through numerical simulations. Overlay difference between the first and second UV-NIL processes resulted in ellipsoidal anisotropic Si-NDs, which exhibited distinct optical responses depending on the linear polarization direction of the incident light. A calibration curve between overlay difference and the spectral shift of the magnetic dipole (MD) mode demonstrated excellent linearity, thereby enabling sub-nanometer precision in overlay detection. These spectral changes caused by geometric anisotropy are systematically explained using a well-defined Mie resonance model. As the method relies on microscopic spectroscopy, it is scalable, nondestructive, and suitable for large-scale fabrication of metasurfaces and meta-optics, thereby offering significant advantages over conventional techniques.