Wafer eccentricity estimation with disturbance caused by alignment notch

The electronics industry is relying increasingly on robotics for its production. High accuracy wafer handling is critical in semiconductor manufacturing. Typical pre-alignment wafer eccentricity identification is time-consuming because a pick-measure-place method is used. To improve the wafer handling efficiency, it is necessary to speed up the measurement process or place it in parallel with other operations. Our previous work proposed and implemented dynamic wafer handling methods using optic sensors to replace the pre-alignment methods. Our proposed methods improve the wafer handling efficiency greatly and achieve satisfactory eccentricity identification results. However, the wafer eccentricity estimation with disturbance caused by the wafer notch is not addressed. In this paper, we propose a method to eliminate the disturbance caused by the wafer notch such that the wafer eccentricity identification accuracy can be improved. The proposed method is also compared with the other method. Experiments were performed to validate the proposed method and the results demonstrate the effectiveness of the proposed method.