Method for manufacturing composite substrates

Abstract

A method for manufacturing a composite substrate is provided, which can form a modified layer with a thickness of a predetermined value or more and can suppress the peeling of the active layer. The method for manufacturing a composite substrate according to an embodiment of the present invention includes: forming an active layer on at least one side of a crystalline support substrate; and forming a modified layer on the surface side of the support substrate by irradiating the surface of the support substrate with a pulsed laser from the active layer side; wherein the thickness of the modified layer is 10 nm or more due to the irradiation with the pulsed laser.