Composite substrate and method for manufacturing same
[Problem] To provide a composite substrate which includes a silicon substrate having few lattice defects. [Solution] A composite substrate ( 50 ) that comprises a first substrate ( 10 ), which is constituted of a semiconductor material, a second substrate ( 40 ), which is constituted of an insulating material, and an oxide layer ( 30 ) and a semiconducting epitaxial layer ( 20 ) which have been disposed between the substrates ( 10 ) and ( 40 ) in this order from the second substrate ( 40 ) side, the oxide layer ( 30 ) having oxygen atoms arranged on the side thereof which faces the epitaxial layer ( 20 ).
1. A method for manufacturing a composite substrate, the method comprising:
preparing a first substrate comprising a semiconductor material and a second substrate comprising an insulating material;
forming an epitaxial layer having semiconductor characteristics on the first substrate;
forming an oxide layer on the epitaxial layer by an Atomic Layer Deposition method; and
bonding the second substrate to the oxide layer to obtain a composite substrate.
2. The method for manufacturing a composite substrate according to claim 1 , wherein forming the oxide layer comprises:
supplying oxide atoms and metal atoms alternately and repeatedly; and
stopping the forming oxide layer after metal atoms are supplied.
3. The method for manufacturing a composite substrate according to claim 1 , wherein
the semiconductor material comprises silicon,
the insulating material comprises sapphire,
the epitaxial layer comprises silicon, and
the oxide layer comprises aluminum oxide.