A. Callegari et al., OPTICAL-PROPERTIES OF HYDROGENATED AMORPHOUS-CARBON FILM FOR ATTENUATED PHASE-SHIFT MASK APPLICATIONS, Journal of vacuum science & technology. B, Microelectronics and nanometer structures processing, measurement and phenomena, 11(6), 1993, pp. 2697-2699
The optical properties of a plasma-deposited amorphous-carbon film hav
e been investigated in the ultraviolet (365 nm) and deep ultraviolet r
ange (248 nm). By varying process conditions, the optical transmission
through the films was tuned from 4% to 20% at 365 nm and from 3% to 9
% at 248 nm. This tuneability was related to the hydrogen content of t
he film as affected by the process parameters. The index of refraction
n measured by spectroscopic ellipsometry is approximately 2 at the wa
velengths used. These optical proper-ties make this film attractive fo
r use in single layer attenuated phase-shift masks for potential appli
cation in 0.25 mum lithography at 365 and 248 nm.