A coarse-to-fine angle automatic correction method for glassivation passivation parts wafer

Abstract

Due to the characteristics of small die size, large number of dies and large initial swing angle of glassivation passivation parts (GPP) wafer, it becomes a more troublesome problem to accurately correct the wafer angle. To solve this difficulty, a coarse-to-fine angle automatic correction method for GPP wafer is proposed in this paper. First, we design and implement the GPP wafer angle automatic correction system. Then, for the large initial wafer swing angle problem, the coarse correction method based on Hough transform line detection and K-Means clustering is presented for coarse correction of wafer angle. Finally, for accurate correction of the coarse-corrected wafer angle, the edge coordinates of multiple dies in the same row in the image are extracted and the fine correction method of wafer angle based on least squares line fitting is achieved. The experimental results show that, compared with other methods, the proposed method can control the mean absolute error of angle correction within 0.02 degree, so as to fulfill stable and reliable wafer angle automatic correction requirement in practice.