Attenuated phase-shifting photomasks fabricated from Cr-based embedded shifter blanks

I-line (365 nm) and G-line (436 nm) attenuated phase shifting photomasks have been developed using single layer Cr- based photoblanks. The absorber layer has a composition gradient that allows the desired transmission to be tuned while maintaining control over reflectivity and phase shift. These photoblanks are manufactured in existing facilities, and masks are processed much like conventional opaque Cr-based materials. They can be inspected and repaired on current equipment with slight modifications. Printing has been demonstrated on current generation steppers. Deep UV extendability of these materials is also being studied, with a 5% Deep UV (248 nm) single layer photoblank chemistry already demonstrated.