Quantification of misalignment in e-beam lithography due to height map error on optically non-uniform substrates for plasmonic nanoantennas

A systematical study of the alignment mismatch caused by the height measurement error in an electron beam lithography system has been performed. The height map error arises when the substrate is transparent or is patterned with optically non-uniform features. A virtual working distance of 23.6 cm has been extracted which allows for an accurate estimate of the importance of height error on misalignment in any e-beam design on optically non-uniform or transparent substrates. Using this technique, we have fabricated Au plasmonic dimer nanoantennas with Indium Tin Oxide (ITO) gap filling. The antennas with ITO show a red shift compared to unloaded antennas due to the increase of dielectric constant in the gap.