Study of shot noise in photoresists for extreme ultraviolet lithography through comparative analysis of line edge roughness in electron beam and extreme ultraviolet lithography

In this paper, the influence of the absorption shot noise on line edge roughness (LER) of photoresists for extreme ultraviolet (EUV) lithography is studied experimentally through the comparative analysis of LER obtained by EUV (92 eV photons) and 100 keV e-beam lithography. Techniques for performing EUV and e-beam lithography with a matched image log slope for a fair comparison of LER values are described. Measurements of absorption of 100 keV electrons estimated through a transmissive electron energy loss spectroscopy measurement with a 120 keV electron beam showed that despite having access to core levels in the material (e.g., 284 eV edge in carbon), these electrons mostly just excite the energy levels less than 100 eV in the resist, with a mean deposited energy of 35 eV. By combining the incident flux and the absorption probabilities, the absorbed quanta for patterning of 50 nm half-pitch line/space features was found to be similar between the two patterning technologies