COMPOSITE SUBSTRATE, ELECTRONIC COMPONENT, AND METHOD FOR MANUFACTURING COMPOSITE SUBSTRATE, AND METHOD FOR MANUFACTURING ELECTRONIC COMPONENT

Provided are a composite substrate which includes a silicon substrate having improved crystallinity, a method for manufacturing a composite substrate, and a method for manufacturing an electronic component. A composite substrate is formed by bonding a semiconductor substrate onto a support substrate having electric insulating properties. The semiconductor substrate is formed of silicon. The semiconductor substrate includes a plurality of first regions on each of which an element portion which functions as a semiconductor device is formed, and a second region which is positioned between the plurality of first regions. In the semiconductor substrate, an oxidized portion which is composed of silicon oxide is formed on a bottom surface of the second region.