Enhanced EUV mask imaging using Fourier ptychographic microscopy

Extreme Ultraviolet (EUV) mask imaging requires higher resolution and phase sensitivity for next-generation lithography. This work explores Fourier Ptychographic Microscopy (FPM) as a solution, addressing challenges such as field-dependent aberrations outside of the miscrope’s designed field-of-view (FOV) for 1D and 2D patterns. Using binary pseudo-random mask patterns (BPRP) and various reconstruction algorithms, we achieve a 1.8× enhancement beyond the 0.5λ/NA resolution limit, improving the resolved feature size from 82 nm to 46 nm across a 30 µm × 30 µm FOV. FPM’s phase reconstruction also enables arbitrary illumination synthesis, allowing for the computational emulation of diverse illumination patterns from a single FPM dataset. These results demonstrate FPM’s potential as a powerful computational imaging tool for high-NA EUV mask imaging and metrology.