| 摘要 |
<p>PURPOSE:To equalize the thickness of a polarization inverting layer and to improve the reliability by setting the thickness of the substrate of the 165 deg. rotation Y plate of a lithium niobate single crystal, the thickness of the titanium film for forming a polarization inverting layer and the thickness of the polarization inverting layer to a prescribed relation. CONSTITUTION:On the upper surface and the lower surface of a piezoelectric single crystal substrate 11 of the lithium niobate, a titanium film 12 is adhered, next, heated and from the upper surface, a polarization inverting layer 13 of thickness alpha is formed. At this time, when the thickness of the substrate 11 is T, the thickness of the film 12 is (t) and the thickness of the layer 13 is alpha, the thickness (t) of the film 12 is set so that alpha/T can become 50%+ or -5%. By controlling the thickness (t) of the film 12 by the method, the dispersion of the thickness of the layer 13 become narrow, for the vibration element with the substrate, the spurious and frequency dislocation are reduced, and the performance and reliability are improved. Being t 2.5T-3.5tX10<-4> and the substrate 11 may be heated at the polarization inverting layer forming temperature.</p> |
