  Deep Ultraviolet (DUV) Photolithography is currently used to fabricate
mass-scale integrated circuits (ICs). Its high throughput and resolution could
benefit large-scale RF MEMS production for the telecommunication market. We
present a process flow to fabricate suspended acoustic resonators using DUV
Photolithography. This method allows for scalable production of resonators with
critical dimensions of 250 nm and alignment accuracy of less than 100 nm. We
show how photoresists and anti-reflective coatings integrate with the process,
help with deposition quality and resolution, and how Ion Beam Etching allows
for vertical sidewalls of the resonators. We measure resonance frequencies (fr)
up to 7.5 GHz and electromechanical couplings up to 8%, and we investigate the
uniformity of this process by analyzing the deviation of fs over the wafer
surface for four main resonance modes. We show that the deviation of the S0
mode can be kept below 1%. These results indicate the suitability of this
process for quick scale-up of Lamb wave resonator technology, bridging the gap
from research to industry.
