Patent ID: 10651818

Abstract:
To provide a method of producing a lithium niobate (LN) substrate which allows treatment conditions regarding a temperature, a time, and the like to be easily managed and in which an in-plane distribution of a volume resistance value is very small, and also variations in volume resistivity are small among substrates machined from the same ingot.A method of producing an LN substrate by using an LN single crystal grown by the Czochralski process, in which a lithium niobate single crystal having a Fe concentration of 50 mass ppm or more and 2000 mass ppm or less in the single crystal and being in a form of an ingot is buried in an Al powder or a mixed powder of Al and Al2O3, and heat-treated at a temperature of 450° C. or more and less than 660° C., which is a melting point of aluminum, to produce a lithium niobate single crystal substrate having a volume resistivity controlled to be within a range of 1×108 Ω·cm or more to 2×1012 Ω·cm or less.