  In this work, we show the feasibility of extreme ultraviolet (EUV) patterning
on an HF-treated Si(100) surface in the absence of a photoresist. EUV
lithography is the leading lithography technique in semiconductor manufacturing
due to its high resolution and throughput, but future progress in resolution
can be hampered because of the inherent limitations of the resists. We show
that EUV photons can induce surface reactions on a partially H-terminated Si
surface and assist the growth of an oxide layer, which serves as an etch mask.
This mechanism is different from the H-desorption in scanning tunneling
microscopy-based lithography. We achieve SiO2/Si gratings with 75 nm half-pitch
and 31 nm height, demonstrating the efficacy of the method and the feasibility
of patterning with EUV lithography without the use of a photoresist. Further
development of the resistless EUV lithography method can be a viable approach
to nm-scale lithography by overcoming the inherent resolution and roughness
limitations of photoresist materials.
