TiSi-nitride attenuating phase-shift photomask for 193 nm lithography

We have developed a new attenuating embedded phase-shift mask blank for 193 nm lithography based on novel TiSi-nitride chemistry. At 193 nm, these materials offer high optical transmission, they are radiation damage resistant, stable in common chemicals used to strip photoresist, process compatible with use of a hard Cr etch mask, and exhibit excellent dry etch selectivity to quartz. Specifically, optical transmissions of greater than 10% were achieved in films with 180 0 phase-shift. Irradiation at 6 mJ/cm 2 /pulse, or ~60x the energy densities in commercial steppers, caused negligible change in optical transmission for doses up to 2 kJ/cm 2 . Dry etching in an ICP reactor with CF4+He or CHF3+O2 all gave greater than 6:1 etch selectivity to quartz, for optimized conditions. Further, the novel wavelength-tunable structure of these TiSi-nitride films permits equally attractive phase-shift designs at 248 nm and longer wavelengths. Currently, printing performance is under evaluation, and these properties will also be reported.