Iterative algorithm for automatic alignment by object transformation

Mathematical model for automatic alignment of wafers was derived under the assumption of the ideal condition of alignment marks. Because wafers were fabricated under nonideal conditions at the factory level, the wafers were difficult to handle during the manufacturing process. The difficulty arose from distortion due to dust, water and contaminant. The errors from the distortion could be reduced when an ideal algorithm was applied to the alignment sequence repeatedly. The alignment algorithm, which was modified to be iterative, is based on the object transformation and composed of matrix operations like a linear model. The accuracy of the algorithm was demonstrated with a dicing machine in our experiment. The result showed that this iterative algorithm was simple but accurate enough to be applied at the manufacturing level.

[1]  Alexander H. Slocum,et al.  Precision passive mechanical alignment of wafers , 2003 .

[2]  Vera B. Anand.  Computer Graphics and Geometric Modeling for Engineers , 1993 .

[3]  S. D. Collins,et al.  A wafer-to-wafer alignment technique , 1989 .

[4]  Erik H. Anderson,et al.  Sub-pixel alignment for direct-write electron beam lithography , 2004 .

[5]  Y. S. Tarng,et al.  A new algorithm for a three-axis auto-alignment system using vision inspection , 2006 .

[6]  Sheng Liu,et al.  NIL - a low-cost and high-throughput MEMS fabrication method compatible with IC manufacturing technology , 2006, Microelectron. J..

[7]  C.S. Song,et al.  Matrix form of automatic alignment algorithm in 2D space , 2004, Proceedings of the IEEE International Conference on Mechatronics, 2004. ICM '04..

[8]  Singiresu S Rao,et al.  Applied numerical methods for engineers and scientists , 2001 .

[9]  Hyong Tae Kim,et al.  2-Step algorithm for automatic alignment in wafer dicing process , 2004, Microelectron. Reliab..

[10]  HyungTae Kim,et al.  Convergence Analysis of Wafer Alignment Algorithm Based on Object Transformation , 2006, 2006 1ST IEEE Conference on Industrial Electronics and Applications.

[11]  Carola Strandman,et al.  Passive and fixed alignment of devices using flexible silicon elements formed by selective etching , 1998 .

[12]  Hyeran Kim,et al.  Iterative algorithm for automatic alignment by object transformation , 2005 .

[13]  Seung-Woo Kim,et al.  An ultraprecision stage for alignment of wafers in advanced microlithography , 1997 .

[14]  Hyong Tae Kim,et al.  Algorithm for automatic alignment in 2D space by object transformation , 2006, Microelectron. Reliab..