No abstract

We demonstrate that the use of a single SiO 2 film, with thickness corresponding to one standing wave (SW) period allows the recording of deep photoresist structures on silicon substrates by laser interference, without use of any additional antireflecting coating. This condition corresponds just to the opposite thickness (half SW period) previously proposed for using the SiO 2 films for phase-shifting the SW pattern. Theoretical and experimental results demonstrated that for the lithography of deep structures, the contrast of the SW pattern, the minimum light intensity of the SW pattern and the photoresist adhesion are the most important parameters of the process.

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2D hexagonal patterns can be generated by the superimposition of two or three fringe patterns that have been formed by two-wave interference and that have rotations of 60 degrees between them. Superimposing three exposures solves the problem of asymmetry in the cross section of structures, which is caused by double exposure. The resulting structure, however, depends on the phase shift of the third fringe pattern in relation to the previous two. We propose a method for controlling the phase shift, and we demonstrate that three different lattice geometries of hexagonal photonic crystals can be recorded when the phase is chosen.

No abstract