Fundamental study of extreme UV resist line edge roughness: Characterization, experiment, and modeling

Mitigation of line edge roughness (LER) remains a significant practical issue for extreme ultraviolet (EUV) resist performance at 22 nm dimensions and below. The authors have applied a suite of experimental characterization techniques and simulation methods to a set of model EUV resists with the aim of strengthening fundamental understanding of the nature and origins of LER. The influence of resist film composition on LER has been evaluated for positive-tone chemically amplified polymer and NORIA molecular glass resists, and has been correlated the effects with surface roughness on resist films exposed at doses comparable to those at the image line edge. The effect of developer type on LER has been characterized using two distinct developer compositions that provide aqueous base positive-tone and organic solvent negative-tone processes. The time evolution of image roughness during pattern development has been visualized using interrupted development in a flow cell configuration that halts the dissolution ...