Abstract
The half-tone phase shift mask (PSM) has been suggested for better imaging performances like image contrast,
NILS and H-V bias compared to the binary mask (BIM) in EUV lithography. In this paper, we measured
imaging performance of a fabricated half-tone attenuated PSM with Coherent Scattering Microscopy (CSM) and
the results were compared with simulation data obtained by EM-suite tool. We prepared a half-tone attenuated
PSM which has 12.7% reflectivity and 180° phase shift with absorber stack of 16.5mn-thick TaN absorber and
24nm-thick Mo phase shifter. With CSM, an actinic inspection tool, we measured the imaging properties of
PSM. The diffraction efficiencies of BIM were measured as 31%, 36%, and 44% for 88 nm, 100 nm, and 128
nm mask CD, respectively, while those of PSM were measured as 45%, 62%, and 81%. Also the aerial image at
wafer level obtained by CSM with high volume manufacturing tool’s (HVM) illumination condition (NA=0.33,
σ=0.9) showed higher image contrast and NILS with phase shift effect. And the measured data were consistent
with the simulation data.
