Or. Wood et al., USE OF ATTENUATED PHASE MASKS IN EXTREME-ULTRAVIOLET LITHOGRAPHY, Journal of vacuum science & technology. B, Microelectronics and nanometer structures processing, measurement and phenomena, 15(6), 1997, pp. 2448-2451
We have used an attenuated phase mask, a mask with a rr-phase shifting
attenuator, in extreme ultraviolet lithography at 13.9 nm wavelength
to produce resist profiles with sharper, more vertical sidewalls. (C)
1997 American Vacuum Society.