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

Abstract

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 CF 4 +He or CHF 3 +O 2 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.

UV light with oxygen treatment of phase shift photoblank for phase and transmission control: applicable to M x Si (1-x) O y N (y-1)

“…SiN-TiN multilayer films were developed by Dupont Photomask. This material fully qualifies as a shifter for phase shift mask (PSM) applications [2] . Although the top layer of SiN is known to be chemically resistant, the films present similar sensitivity as MoSiON films toward aggressive cleans.…”