ATTENUATED PHASE-SHIFT MASK MATERIALS FOR 248 AND 193 NM LITHOGRAPHY

In order to push resolution toward diffraction limits for 248 and 193 nm lithography, it is likely that some combination of optical enhancem ent may be needed. The attenuated phase shift mask approach may prove to be one of the less complex techniques available. Four materials are presented which may meet optical and process requirements for use as attenuated phase shift mask films: a molybdenum silicon oxide composit e, an aluminum/aluminum nitride cermet, an understoichiometric silicon nitride, and a tantalum silicon oxide composite. All of these materia ls are shown to be capable of 4%-15% transmission at 193 nm with thick nesses that produce a pi phase shift. Evaluation of addition film prop erties including plasma reactive ion etch and long wavelength transmis sion helps in establishing materials which may be most production wort hy. (C) 1996 American Vacuum Society.