We are investigating the effect of pupil-fill patterns and partial coherence settings on EUV reticle images on the new
SEMATECH High-NA Actinic Reticle review Project (SHARP), to deepen our understanding of its performance, and
improve the emulation of image formation in arbitrary printing tools. SHARP is an EUV mask microscope developed as
the successor of the SEMATECH Berkeley Actinic Inspection Tool (AIT). It is equipped with a unique, MEMS-based
Fourier synthesis illuminator that generates arbitrary, customized pupil fill patterns to control the illumination partial
coherence. The high-magnification objective lenses are an array of interchangeable Fresnel zoneplates with 4×NA values
ranging from 0.25 to 0.625.
We have used SHARP to inspect isolated and dense features with half pitch as low as 55 nm using lenses with a range of
NA values, and common illumination patterns, such as annular, dipole and QUASAR™. We will show the effect of
illumination on important, measured pattern parameters, including contrast, normalized image log-slope, and depth of
We have also studied the effect of partial coherence on the imaging of on multilayer roughness observed in bright mask
regions, a topic important for expanding our understanding of the causes of LER.