US Patent 11597039 Wafer producing method and laser processing apparatus

A wafer producing apparatus detects a facet area from an upper surface of an SiC ingot, sets X and Y coordinates of plural points lying on a boundary between the facet area and a nonfacet area in an XY plane, and sets a focal point of a laser beam having a transmission wavelength to SiC inside the SiC ingot at a predetermined depth from the upper surface of the SiC ingot. The predetermined depth corresponds to the thickness of the SiC wafer to be produced. A control unit increases the energy of the laser beam and raises a position of the focal point in applying the laser beam to the facet area as compared with the energy of the laser beam and a position of the focal point in applying the laser beam to the nonfacet area, according to the X and Y coordinates.