A procedure for the postfabrication frequency adjustment (trimming) of narrow‐band surface acoustic wave devices on quartz is described. This procedure utilizes selective etching of a quartz substrate by means of a tetrafluoromethane + oxygen (CF4+O2) plasma, to permanently change the physical configuration of the transducers by increasing the step height of metal electrode structures. An increase in energy storage at the step edges and an increase in transducer reflectivity (for resonators) contribute to a reduction in device frequency. This technique is simple, it may be readily implemented using several types of equipment, and the long‐term aging rate of a devce is not changed. The technique may be used for resonators, which may be trimmed by etching the transducers only, and with delay‐line type filters having any electrode configuration.
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