The application of the correlation method for the EB (electron beam) exposure system

In EB direct wafer writing, we have applied the correlation method to detecting the position of the registration mark and we also applied it to detecting the width of the mark, the size of the beam and the degree of focusing for the calibration of the EB exposure system. This method is less influenced by random noises and has wide capability for the signal forms. We have also developed a detection hardware unit and applied it to our variable shaped EB exposure system JBX-8600DV with satisfactory results. The reliability of detection of the mark position is 0.05 µmpp by single scanning; that of the beam size is 0.02 µmpp. We can adjust the focus to within ±3 µm.