Extreme ultraviolet–embedded phase-shift mask

Abstract

Extreme ultraviolet lithography (EUVL)-embedded phase-shift mask (EPSM) for 16-nm half-pitch node technology and beyond generations will provide improvements in process window and low shadowing effect as compared to those of the conventional EUVL binary mask. In a previous study, we experimentally demonstrated the advantages of the EUVL EPSM for the dense lines and contacts as compared to those of the standard EUVL mask. In this study, we focused more on systematic analysis and comparison of the process windows between EUVL EPSM and conventional EUVL binary mask for various feature types. In addition, we investigated the EUVL EPSM performances as a function of phase errors in order to further define the EUVL EPSM absorber thickness uniformity requirements. Both the EUVL EPSM and binary mask were exposed at the Alpha Demo Tool at IMEC, and the wafer level data show features in the EPSM have a larger process window, lower dose-to-target value, and reduced shadowing effect as compared to those of the conventional EUVL binary mask.