Broadband extreme ultraviolet zeroth order scatterometry for nanostructure metrology

Abstract

Abstract The continuous shrinkage of critical dimensions in nanofabrication demands nanometrology at the relevant resolution, which can be achieved using short-wavelength light sources. Most industrial metrology uses periodic structures for process control, exploiting diffraction to probe the fabrication quality of actual device structures. Here, we introduce a table-top high-harmonic generation extreme-ultraviolet scatterometry with broadband illumination. Our method exploits the spectrally resolved 0 th diffraction order of the extreme-ultraviolet light, which, while lacking spatial-encoded information, carries valuable spectral information and offers high diffraction efficiency. The use of relative reflectivity removes the need for absolute calibration, and rigorous coupled-wave analysis simulations underpin a library-based reconstruction approach, yielding single-nanometer accuracy for groove height and 10 nm accuracy for critical dimensions. Our work demonstrates broadband extreme-ultraviolet high-harmonic-generation 0 th order scatterometry that delivers fast, reliable, non-destructive metrology for structures with at-wavelength features, providing sensitivity and accuracy for details far below the diffraction limit.