Jc. Wolfe et al., A PROXIMITY ION-BEAM LITHOGRAPHY PROCESS FOR HIGH-DENSITY NANOSTRUCTURES, Journal of vacuum science & technology. B, Microelectronics and nanometer structures processing, measurement and phenomena, 14(6), 1996, pp. 3896-3899
Image contrast in proximity ion beam lithography is limited by scatter
ed ions which enter the opaque regions of the mask and exit through th
e sidewalls of the mask windows. The scattering angles are widely dist
ributed resulting in a ''proximity effect'' whose range is on the orde
r of the mask-to-wafer gap. This problem becomes more severe with incr
easing pattern density and sets the resolution limit for high density
patterns such as interdigital transducers, The only way to counteract
this effect is to limit the ion range to a fraction of the mask thickn
ess so that the scattered ions can be recaptured by adjacent sidewalls
. This article explores the dependence of image contrast on resolution
, pattern density, and beam energy in proximity ion beam lithography.
Patterns with feature sizes in the range from 20 to 50 nm and 0.4 mu m
pitch have been printed with a linewidth change of only 3 nm for a 10
% change in dose. (C) 1996 American Vacuum Society.