Wafer positioning by laser scanning method

A laser scanning method for wafer positioning is proposed. This wafer positioning method incorporates a laser scanner system and a scattering light receiving system. The scanner is used to reflect a laser beam into a scanning line on the sensing area. As the wafer passes by the scanning line, a scattering light receiving system detects the time-sequence signal of the scattered lights. The position of wafer relative to the robot plate is determined by signal processing of the time-sequence signal. The measurement precision is about 0.3 mm.