Patent ID: 7910465

Claim:
A manufacturing method of a semiconductor substrate, comprising the steps of: irradiating a surface of a single crystal semiconductor substrate with ions to form a damaged region; forming an insulating layer over the surface of the single crystal semiconductor substrate; making a surface of a substrate having an insulating surface be in contact with a surface of the insulating layer to bond the substrate having the insulating surface to the single crystal semiconductor substrate; separating the single crystal semiconductor substrate at the damaged region by performing heat treatment to form a single crystal semiconductor layer over the substrate having the insulating surface; patterning the single crystal semiconductor layer to form a plurality of island-shaped semiconductor layers; irradiating at least one of the island-shaped semiconductor layers with a laser beam which is shaped to entirely cover the at least one of the island-shaped semiconductor layers; evaluating a melted state of the at least one of the island-shaped semiconductor layers during the irradiation with the laser beam; judging the melted state of the at least one of the island-shaped semiconductor layers whether melted or unmelted; and irradiating at least one of the island-shaped semiconductor layers with the laser beam which is shaped to entirely cover the at least one of the island-shaped semiconductor layers after judging that the at least one of the island-shaped semiconductor layers is unmelted, wherein the evaluating step comprises: irradiating a top surface or a rear surface of the at least one of the island-shaped semiconductor layers with a reference laser beam having a predetermined wavelength; and measuring a reflectance of the reference laser beam, wherein a result of the judging the melted state of the at least one of the island-shaped semiconductor layers is selected from an unmelted state, a partially-melted state and a completely-melted state based on the measured reflectance of the reference laser beam.