| 摘要 |
PROBLEM TO BE SOLVED: To provide a laser processing method of a wafer that can reduce a risk to wrongly detect a modified layer formed inside the wafer.SOLUTION: A laser processing method of a wafer includes: a first imaging step which detects a scheduled split line 13 and obtains a first captured image by infrared ray imaging means from a rear surface of the wafer; a modified layer formation step which, after the first imaging step, irradiates a laser beam of a wavelength having a transmissivity through the wafer from the rear surface side of the wafer with a light condensing point set in the inside near the surface of the wafer and forms a modified layer 21 in the inside near the wafer surface; a second imaging step which, after the modified layer is formed along at least a part of the scheduled split line, detects the scheduled split lines where the modified layers are formed, and obtains a second captured image by the infrared ray imaging means from the rear surface of the wafer; and a modified layer clarifying step which contrasts the first captured image with the second captured image, extracts a part which is not common, and clarifies the modified layers. |
