Convergence Analysis of Wafer Alignment Algorithm Based on Object Transformation

This paper analyzes the convergence of the automatic wafer alignment algorithm, which is similar to numerical root-finding. An iterative, simple equation for wafer alignment with a convergence constant was derived from object transformation. The convergence speed of the iteration could be varying the convergence constant eta. To demonstrate the algorithm, an experiment for an alignment was done on the dicing machine. The alignment was repeated until the error was under sub-pixel level on the inspection system. The constant was varied to monitor its effect on iterative alignment speed. The result showed the convergence speed could be controlled but the compensation values found by the iterative action had the same solution