Mark detection in electron beam lithography using evaluation of wave signal symmetry

A new mark detection method has been developed using the symmetry of mark signals. The calculation of the symmetry is executed by a digital signal processor in order to reduce the detection time to less than 100 msec. Detection accuracy is estimated by a simulator. Calculated accuracy is compared with experiment results. The detection system is adopted in a new electron beam lithography system⁽¹⁾.