New solutions for inspection contrast tuning, enhanced chemical durability, and a new ultrahigh-transmission PSM

Schott's already commercially available two layer Ta/SiO2 phase shift system can be tuned from 6% up to 30% transmission for 157, 193 and 248 nm lithography wavelengths. Thus one film patterning process provides a wide product range. Dry etch process development is done at IMS chips in Stuttgart, Germany, to provide our customers the service of a good start process for patterning. Our newest development enhances our phase shift layer system. An inspection layer provides an improved contrast for inspection at 257 nm and 365 nm by adjusting reflection to the optimum range from 7% to 20%. Chemical durability against standard mask cleanings was already shown to be good but can be further enhanced by an protection layer. Furthermore a new two layer phase shift system was designed achieving ultra-high transmission above 90% at 193 nm lithography wavelength as an alternative to hard shifter masks.