Fab Implementation: MfD Response 169
lithography (DPIL), making EUVL more of a tactical MfD response than a
signicant improvement in technology capability. The wafer throughput of
the vacuum-based EUVL exposure tool is limited to a few wafers/hour [11].
Another EUV manufacturability challenge is optimizing PR (photo resist)
thickness. Resist as thin as the pitch would ensure more uniform absorption
and reduce forward scattering from the secondary electrons, but the result-
ing small devices would be subject to increased irradiation by photoelec-
trons, creating reliability concerns.
While the nominal line resolution expressed by the Rayleigh equation
seems to make EUV a major MfD improvement over standard lithography,
an abrupt reduction ...