SiO2 single layer for reduction of the standing wave effects in the interference lithography of deep photoresist structures on Si

We demonstrate that the use of a single SiO₂ 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 SiO₂ 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.