Elucidating The Role of Electrons in Extreme Ultraviolet Patterning Variability

Abstract

While there has been tremendous recent progress in the deployment of full-field high numerical aperture (NA) scanners, it is generally understood that the practical viability of these amazing tools being able to achieve their full resolution capabilities in production is, to a large extent, constrained by parallel improvements in both photoresists and photomasks. In this manuscript the unique role electrons play in EUV lithography and, in particular, how these electrons impact patterning variability is addressed. New expressions for the electron image shot noise and the electron image log slope are derived, yielding a complete EUV-relevant local patterning variability equation. Using this new formulation, experimental patterning results are evaluated demonstrating the non-negligible impact of electron blur in EUV patterning with the results indicating an electron range of approximately 3 nm.