Materials screening for attenuating embedded phase-shift photoblanks for DUV and 193 nm photolithography

We surveyed more than 150 different materials as candidates for optically tunable (at 248 nm and 193 nm), attenuating embedded phase-shift masks. Multicomponent materials with four distinct microstructures: (1) composites, (2) cermets, (3) multilayers, and (4) copolymers, where one component was optically clear at the application wavelength and the other component more optically absorbing, provided a systematic approach for adjusting the needed optical properties: specifically, optical transmission and π-phase-shift. From evaluation of optical properties and other mask manufacturability issues, including chemical and radiation durability, etch selectivity, alignment and inspection properties, film stress and adhesion, we identified promising nitride and oxide materials based on MNx-AlN (M=Cr, Mo, W,...) and M'Oy-RuO2 (M'=Al, Hf, Zr...) as well as promising polymers.