METHOD OF PRODUCING LITHIUM TANTALATE SINGLE CRYSTAL SUBSTRATE FOR ELASTIC SURFACE WAVE ELEMENT AND LITHIUM TANTALATE SINGLE CRYSTAL SUBSTRATE FOR ELASTIC SURFACE WAVE ELEMENT

摘要

PROBLEM TO BE SOLVED: To provide a method of producing a lithium tantalate single crystal substrate for an elastic surface wave element which has a pseudo-stoichiometric composition provided with a pyroelectricity preventive measure by subjecting a lithium tantalate single crystal substrate treated by a gas phase method to a pyroelectricity removal treatment and the lithium tantalate single crystal substrate for an elastic surface wave element.;SOLUTION: A method of producing a lithium tantalate single crystal substrate for an elastic surface wave element includes a first step of exposing a substrate having a congruent composition and a surface roughness of both sides of 100-500 nm to Li₂O vapor to disperse Li from the surface of the substrate to the central part so as to modify the congruent composition to a pseudo-stoichiometric composition (composition change), a second step of applying a voltage to the substrate in the Z-axis direction, a third step of exposing the substrate to a reduction atmosphere to carry out a pyroelectricity removal treatment, and a fourth step of polishing the substrate. The more rough the substrate is, the more the modification and the modification in the depth direction progress well.;COPYRIGHT: (C)2015,JPO&INPIT