Wafer, wafer manufacturing method, and device chip manufacturing method

A wafer manufacturing method for manufacturing a wafer from an ingot, the wafer manufacturing method comprising:

• a slicing step of producing a plurality of the wafers by slicing the ingot;
• a grinding step of grinding the wafer produced in the slicing step, into a predetermined thickness;
• a polishing step of polishing one or both of a top surface and an undersurface of the wafer ground in the grinding step;
• a resistivity measuring step of measuring resistivity of the wafer;
• and
• an information printing step of forming a character, a number, or a mark representing information regarding the resistivity on one or more of the top surface, the undersurface, and an inside of the wafer after the resistivity measuring step.

A wafer manufacturing method for manufacturing a wafer from an ingot, the wafer manufacturing method comprising:

• a planarizing step of planarizing an end surface of the ingot;
• a resistivity measuring step of measuring resistivity of the ingot at the planarized end surface;
• a peeling layer forming step of forming a peeling layer within the ingot by positioning a condensing point of a first laser beam having a wavelength transmissible through the ingot at a depth corresponding to a thickness of the wafer to be produced from the end surface, and irradiating the ingot with the first laser beam;
• an information printing step of forming a character, a number, or a mark representing information regarding the resistivity measured in the resistivity measuring step on one or both of the planarized end surface and an inside of the ingot by positioning a condensing point of a second laser beam in a region in which devices are not to be formed in the wafer to be produced, and irradiating the ingot with the second laser beam;
• and
• a wafer producing step of producing the wafer by dividing the ingot with the peeling layer as a starting point and peeling off the produced wafer.

A device chip manufacturing method for manufacturing a plurality of device chips by dividing a wafer by laser processing, a plurality of planned dividing lines intersecting each other being set on a top surface of the wafer, a device being formed in each of regions demarcated by the planned dividing lines on the top surface, the device chip manufacturing method comprising:

• a loading step of loading the wafer into a laser processing apparatus;
• a laser processing step of forming modified layers within the wafer along the planned dividing lines by positioning a condensing point of a laser beam having a wavelength passing through the wafer within the wafer, and applying the laser beam to the condensing point while moving the condensing point and the wafer relative to each other in a direction parallel with the top surface;
• and
• a dividing step of manufacturing a plurality of the device chips by dividing the wafer with the modified layers as a starting point,
• wherein a character, a number, or a mark representing information regarding resistivity of the wafer is formed in or on the wafer, and
• in the laser processing step, the wafer is irradiated with the laser beam under an irradiation condition determined on a basis of the resistivity of the wafer, the resistivity being able to be obtained from the character, the number, or the mark representing the information regarding the resistivity of the wafer.