Impact of EUV resist thickness on local critical dimension uniformities for <30 nm CD via patterning

This paper describes the impact of Extreme Ultraviolet (EUV) resist thickness on <30 nm Via Local Critical Dimension Uniformity (LCDU) measured during After Development Inspection (ADI) and After Etch Inspection (AEI). For the same post-etch CD targets, increasing resist thickness from 40 to 60 nm helped reduced CD variability. This work was performed via virtual fabrication using Coventor’s SEMulator3D® software and was confirmed experimentally. Post litho and post etch CD variations were introduced by considering lithography dose and focus variations in the model. Lithography and etch models were calibrated using 3D resist profile simulations from HyperLith® and post-etch Cross Section Scanning Electron Microscope (XSEM) images, respectively.