| 摘要 |
PURPOSE:To simplify a photoetching process at the time of the formation of an electrode with the pitch size of input and output cross finger electrodes widened, by forming a SiO2 film on the input and output corss finger electrodes of a piezoelectric body specific times as thick as a basic surface wave. CONSTITUTION:On piezoelectric body 5 using a 128 deg. rotary Y disc-X directional propagation LiNbO3 single crystal, cross finger input electrode 6 and output electrode 7 are formed by photoetching, etc. On piezoelectric body 5 and cross finger electrodes 6 and 7, SiO2 film 8 is formed by RF sputtering being made thicker gradually. As a result, a surface wave with a speed 20% less than that of the basic one is generated at the same time as the basic surface wave nearly when thickness (h) of the SiO2 film exceeds 30% of wavelength (lambda) of an elastic surface wave. Using this surface wave as progressive medium widens the pitch size of the input and output cross finger electrodes of the high-frequency elastic surface wave device, so that photoetching for the formation of electrodes can be simplified. Using Y plate LiNbO3 single crystal with a rotation between 90 deg. and 150 deg. obtains the same effect. |
