LASER PROCESSING METHOD AND LASER PROCESSING DEVICE FOR WAFER

摘要

PROBLEM TO BE SOLVED: To provide a laser processing method and a laser processing device for a wafer which have an altered layer formed inside along streets without causing abrasion even if a plurality of devices formed on a surface of the wafer have defective regions.

SOLUTION: The laser processing method includes a defective region detecting step of detecting the height position of the surface along the streets 21 of the wafer 20 and detecting a defective region 220 lowered blow a prescribed surface height position; and an altered layer forming step of forming the altered layer 201 in the interior of the wafer along the streets except the defective region by stopping irradiating the defective region with a laser light beam when the convergence point of the laser light beam is positioned in the interior of the wafer from the surface side to irradiate the wafer with the laser light beam along the streets.

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