Patent ID: 9494513
Filing Date: 2016-11-15
CPC Classification: G01N,H01L

Claim Text:
1. A detection method of a transmission laser beam for irradiating a laser beam of a wavelength having a transparency to a plate-shaped workpiece having a first face and a second face opposite to the first face upon the workpiece from the first face side with a focal point of the laser beam positioned in the inside of the workpiece to detect laser beam which has passed through the workpiece to the second face side, comprising: a photosensitive sheet positioning step of holding the workpiece on a holding face of a chuck table with a photosensitive sheet, which has a photosensitive layer, interposed therebetween such that the photosensitive layer is opposed to the second face of the workpiece; a laser beam irradiation step of irradiating, after the photosensitive sheet positioning step is performed, the laser beam from the first face side of the workpiece; and a confirmation step of confirming, after the laser beam irradiation step is performed, whether the intensity distribution of the transmission laser beam is symmetrical with respect to the center of the transmission laser beam from a photosensitive reaction region formed in the photosensitive layer of the photosensitive sheet.