SILICON SUBSTRATE INSPECTION DEVICE AND INSPECTION METHOD

PROBLEM TO BE SOLVED: To provide a silicon wafer inspection method and device configured to detect an internal crack even if gray level difference fo an image occurs due to unevenness of crystal grain boundary or an optical system.SOLUTION: A silicon wafer is irradiated with infrared illumination light which is circularly polarized with a circular polarization filter. Reflection light on the front and rear surfaces of the silicon wafer having an inverted polarization direction cannot transmit through the circular polarization filter. If the wafer includes a defect such as a crack, the illumination light is irregularly reflected and unpolarized. The light transmits through the circular polarization filter and can be imaged by a camera. Only the illumination light irregularly reflected due to the defect such as a crack is imaged and detected by an image processing device, thereby allowing detection of the defect such as a crack.