Design and implementation of wafer transporting system for photo lithographer

Wafer transporting system is a vital part of IC manufacturing system. This paper presents the design and implementation of the wafer transporting system. Approaches in pre-aligning process and re-locating process are important to the performance of the system. In pre-aligning, Least Square Circle Fitting is adopted to locate the center of the wafer and the notch of the wafer. In re-locating, Section Linear Interpolation is used to calibrate the sensor and special locations of sensors are applied to calculate the wafer eccentricity relative to the fiducially position. The precision of the whole system is very high.