Si SUBSTRATE MANUFACTURING METHOD

A silicon substrate manufacturing method for manufacturing a silicon substrate from a silicon ingot in which a crystal plane (100) is made to be a flat surface, the silicon substrate manufacturing method comprising:

• a separation band forming step of forming a separation band through positioning a focal point of a laser beam with a wavelength having transmissibility with respect to silicon to a depth equivalent to a thickness of the silicon substrate to be manufactured from the flat surface and irradiating the silicon ingot with the laser beam while relatively moving the focal point and the silicon ingot in a direction <110> parallel to a cross line at which a crystal plane {100} and a crystal plane {111} intersect or a direction [110] orthogonal to the cross line;
• an indexing feed step of executing indexing feed of the focal point and the silicon ingot relatively in a direction orthogonal to a direction in which the separation band is formed;
• and
• a wafer manufacturing step of repeatedly executing the separation band forming step and the indexing feed step to form a separation layer parallel to the crystal plane (100) as a whole inside the silicon ingot and separating the silicon substrate from the silicon ingot at the separation layer to manufacture the silicon substrate.