Low roughness euv lithography

Abstract

Provided herein are methods and related apparatus to smooth the edges of features patterned using extreme ultraviolet (EUV) lithography. In some embodiments, at least one cycle of depositing passivation layer that preferentially collects in crevices of a feature leaving protuberances exposed, and etching the feature to remove the exposed protuberances, thereby smoothing the feature, is performed. The passivation material may preferentially collect in the crevices due to a higher surface to volume ratio in the crevices than in the protuberances. In some embodiments, local critical dimension uniformity (LCDU), a measure of roughness in contact holes, is reduced. In some embodiments, at least one cycle of depositing a thin layer in a plurality of holes formed in photoresist, the holes having different CDs, wherein the thin layer preferentially deposits in the larger CD holes, and anisotropically removing the thin layer to remove it at the bottoms of the holes, is performed.