Composite substrate and method for manufacturing same

A method for manufacturing a composite substrate comprising the steps of:

• preparing a monocrystalline support substrate made from an insulating material, and a monocrystalline semiconductor substrate made from a material with an etching rate for dry etching that is different from that of the support substrate;
• activating a main face of the support substrate and a main face of the monocrystalline semiconductor substrate by irradiating both main faces with a FAB gun;
• supplying a metal to at least one of the activated main face of the monocrystalline support substrate and the activated main face of the monocrystalline semiconductor substrate, the metal made from a metal element excluding each main component of material constituting the monocrystalline support substrate and the semiconductor substrate;
• supplying an inert element selected from the group consisting of Ar, Ne, Xe, and Kr [[Xr]], in an amount such that the number of atoms per unit area is greater than that of the metal and is less than that of the atoms constituting a crystal face exposed to the main face of the monocrystalline semiconductor substrate, to at least one of the activated a main face of the support substrate and the activated main face of the semiconductor substrate;
• bonding the monocrystalline semiconductor substrate main face that has been activated and to which the metal or the inert element has been supplied and the monocrystalline support substrate main face that has been activated and to which the metal or the inert element has been supplied by being brought into contact under normal temperatures;
• thinning the monocrystalline semiconductor substrate into a layered semiconductor part by thinning the semiconductor substrate from another main face of the semiconductor substrate;
• and
• heating the layered semiconductor part and the support substrate at a higher temperature than a eutectic temperature of the metal and the material constituting the layered semiconductor part.