A novel method for real-time wafer positioning during transfer process

This study proposed a novel method for real-time detection of wafer position on a robot blade during the transfer process. The wafer positioning system comprises two line-shaped beams spreading toward a scattering surface on the way of wafer transfer. The images taken from a CCD (charge coupled device) camera mounted above the scattering surface are analyzed, and the instant position of the wafer center on the robot blade during the transfer process can be determined after image processing. The precision for the proposed wafer center detection is about 0.15mm according to the preliminary experimental results.