| 摘要 |
PURPOSE: To obtain stable operation which is hardly influenced by external environments and to decrease changes in the operational voltage with time. CONSTITUTION: The production method includes a process to form optical waveguides on a ferroelectric crystal substrate having an electro-optical effect, a process to form a silicon dioxide on the substrate surface, and a process to form an electrode on the upper surface of the silicon dioxide film. Especially, the process to form the silicon dioxide film is carried out by sputtering under conditions of <=1.5kW RF power and >=0.7Pa sputtering pressure. As for the practical evaluation reference of the film property, when the film is subjected to wet etching by 16-buffered hydrofluoric acid at normal temp., the film is etched at >=150Å/sec etching rate. The silicon dioxide film is made rough so that the tensile and compressive stress to the substrate can be reduced.
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