SAW resonators frequency trimming by plasma etching

SAW resonators need resonant frequency with defined tolerances. The manufacturing process, depending on photolithographic forming of interdigital structures on piezoelectric substrate surface, gives frequency dispersion-in general-higher than required. This situation needs correction of resonator frequency after leads mounting. The SAW resonators frequency trimming is possible by plasma etching of the quartz surface between interdigital structure fingers. The laboratory equipment for plasma etching has been development at the Tele & Radio Research Institute. Using this equipment the experiments with frequency trimming of one port SAW resonators on quartz substrate have been carried out. In this paper construction of the plasma etching laboratory equipment and results of SAW resonators frequency trimming are presented.