The Wafer Alignment Algorithm Regardless of Rotational Center

Wafer alignment is a sequence of translational and rotational movement, so typical alignment algorithms require a rotational center. The method proposed in this paper simplifies the alignment algorithm regardless of the placement of a rotational center. The original algorithm was derived from rigid body transformation, so it had the terms for the rotational center. These terms can be omitted if we make some assumptions on the characteristics of wafer alignment. The derived equation had a form similar to that of root finding in numerical analysis. The algorithm was experimented on the dicing machine and its results were compared with the exact solutions. The result showed that the simplified form was effective enough to be applied for manufacturing. And the iteration speed can be varied by the convergence constant. The derived equation was so simple that the alignment algorithm can be applied to PLC-based systems