Gigahertz SAW filter developed using new submicrometre techniques

A photolithographic technique was developed that uses 1/10-reduction photoprinting with a phase-shifting mask to make gigahertz SAW devices. Combined with a positive-type resist, this new technique produces IDT electrodes with smaller deviations in width compared with using a negative-type resist. Very sharp 40 nm thick AI electrodes with 0.4 μm lines and spaces were achieved. A 2.5 GHz SAW filter suitable for optical communication systems was developed