Wafer producing method

A wafer producing method for producing a wafer from a compound single crystal ingot having a first end surface and a second end surface opposite to the first end surface, the wafer producing method comprising:

• a separation plane forming step of holding the second end surface of the compound single crystal ingot on a chuck table, next setting a focal point of a laser beam having a transmission wavelength to the ingot inside the ingot at a predetermined depth from the first end surface of the ingot, which depth corresponds to a thickness of the wafer to be produced, and next applying the laser beam to the first end surface as relatively moving the focal point and the ingot to thereby form a modified layer parallel to the first end surface and cracks extending from the modified layer, thus forming a separation plane containing the modified layer and the cracks;
• a wafer producing step of separating a plate-shaped member having a thickness corresponding to the thickness of the wafer from the ingot at the separation plane after performing the separation plane forming step, thus producing the wafer from the ingot;
• and
• a flattening step of grinding the first end surface of the ingot after performing the wafer producing step, thus flattening the front end surface of the ingot,
• wherein the ingot is composed of first atoms having a larger atomic weight and second atoms having a smaller atomic weight, the first end surface of the ingot being set as a polar plane where the second atoms having a smaller atomic weight are arranged in performing the separation plane forming step, and
• the first end surface as the polar plane where the second atoms having a smaller atomic weight are arranged is ground in the flattening step,
• wherein the compound single crystal ingot is a SiC ingot, and the first end surface is set as a polar plane where carbon (C) atoms are arranged.