Method for producing composite wafer having oxide single-crystal film

Abstract

Provided is a composite wafer (c-wafer) having an oxide single-crystal film transferred onto a support wafer (s-wafer), the film being a lithium tantalate or lithium niobate film, and c-wafer being unlikely to have cracking or peeling caused in the lamination interface between the film and s-wafer. More specifically, provided is a method of producing c-wafer, including steps of: implanting hydrogen atom ions or molecule ions from a surface of the oxide wafer (o-wafer) to form an ion-implanted layer inside thereof; subjecting at least one of the surface of o-wafer and a surface of s-wafer to surface activation; bonding the surfaces together to obtain a laminate; providing at least one of the surfaces of the laminate with a protection wafer having thermal expansion coefficient smaller than that of o-wafer; and heat-treating the laminate with the protection wafer at 80° C. or higher to split the laminate along the layer to obtain c-wafer.