Abstract: A reference wafer for calibrating a laser and a camera and checking laser accuracy and spot size. The reference wafer may include a light absorption layer on a semiconductor substrate and a light reflection layer pattern on the light absorption layer. The light reflection layer pattern may include a first pattern for checking the laser accuracy and spot size and a second pattern for calibrating the laser and camera. A first anti-reflective layer may be introduced between the light absorption layer and the semiconductor substrate, and a second anti-reflective layer may be introduced between the light absorption layer and the light reflection layer pattern.