Abstract: A method of manufacturing a small-diameter wafer from a wafer having one face and the other face, the one face being mirror-polished, is provided. The method includes a protective member covering step of covering the one face of the wafer with a first protective member and the other face of the wafer with a second protective member, a cut-out step of cutting out a plurality of small-diameter wafers from the wafer covered with the first protective member and the second protective member, a chamfering step of chamfering an outer periphery portion of each of the plurality of small-diameter wafers, and a protective member removing step of removing the first protective member and the second protective member from each of the plurality of small-diameter wafers.

Abstract: Provided is a composite substrate manufacturing method, including at least: a first raw board deforming step of preparing a first substrate by deforming a first raw board having at least one surface as a minor surface into a state in which the minor surface warps outward; and a joining step of joining, after the first raw board deforming step, a protruding surface of the first substrate and one surface of a second substrate to each other, thereby manufacturing a composite substrate including the first substrate and the second substrate, in which the second substrate is any one substrate selected from a substrate having both surfaces as substantially flat surfaces and a substrate that warps so that a surface thereof to be joined to the first substrate warps outward. Also provided are a semiconductor element manufacturing method, a composite substrate and a semiconductor element manufactured.

Abstract: Provided is a composite substrate manufacturing method, including at least: a first raw board deforming step of preparing a first substrate by deforming a first raw board having at least one surface as a minor surface into a state in which the minor surface warps outward; and a joining step of joining, after the first raw board deforming step, a protruding surface of the first substrate and one surface of a second substrate to each other, thereby manufacturing a composite substrate including the first substrate and the second substrate, in which the second substrate is any one substrate selected from a substrate having both surfaces as substantially flat surfaces and a substrate that warps so that a surface thereof to be joined to the first substrate warps outward. Also provided are a semiconductor element manufacturing method, a composite substrate and a semiconductor element manufactured.