PURPOSE: To form the surface wave device which has specific frequency characteristics by oxidizing or nitrifying the surfaces of comb-line electrodes on a piezoelectric substrate and adjusting the mass of the interdigital electrodes.
CONSTITUTION: The interdigital electrodes 2 are formed of aluminum on the piezoelectric substrate 1 of crystal of the surface wave device. This substrate 1 is set on a substrate stage 6 and the frequency characteristics of the substrate 1 are detected in a vacuum state by using a probe 5 for frequency characteristic detection and a frequency characteristic detection device 7. When the frequency is high, it is decided that the thickness of the electrodes 2 is thin, the substrate 1 is mounted on a substrate stage 11, and while oxygen or nitrogen is fed through a gas intake 14, the laser light from a laser 12 sweeps the substrate 1 for a necessary time based upon the detected frequency. Then the surfaces of the electrodes 2 are oxidized or nitrified and the thickness of the electrodes 2 reaches necessary thickness because of the oxidized layers or nitrified layers, thereby obtaining the piezoelectric substrate of the surface wave device which has the specific frequency characteristics.
SHIOKAWA AKIRA
KODERA KOICHI
