Material optimization of the alignment marks for the EBDW lithography

We present results of material optimization for the alignment marks used in the Electron-Beam Direct-Write (EBDW) lithography. Such marks have been proposed both for negative (grooves) as well as for positive (elevated) topographies. The primary mask for the alignment mark patterns is done by photolithography and e-beam lithography. The negative topography of the marks was transferred by Deep Reactive Ion Etching (DRIE), while the positive topographies were realized by evaporation of various metals followed by lift-off process. We measured signals at characteristic beam-steps when the e-beam scans across the mark. This was done on two scanning positions. Out of these measurements we obtained the detection signal characteristics for different fiducial alignment marks with positive and negative topographies, respectively.