Characteristics of gap-induced aberration in solid immersion lens systems

The induced phase changes are quantified by varying air gap width. Experiment shows the shape of the gap-induced aberration is well predicted by our simulation. The aberration is characterized by three parameters. The analyzed solid immersion lens (SIL) system is composed of SIL, gap, and substrate. The air gap induces instrumental polarization aberration due to vector thin-film effects. For larger air gaps the changes of phase increase. The astigmatic spot is explained by the increased aberration. Experiment confirms simulation at 300 nm air gap for LaSFN9 (SIL/substrate).