Direct Writing of Nanoscale Patterns in SiO₂

Abstract

SiO₂ is a material with many useful physical properties and for which there are well-established processing techniques. It has been used in many semiconductor devices. About two years ago at Cambridge it was demonstrated that SiO₂ could also be used directly as an electron resist with ultra-high resolution. The process, which relies on the electron beam irradiation induced etch-rate enhancement of SiO₂ in hydrofluoric acid based etches, has already shown better resolutions than PMMA, the most studied electron resist. However, it does require a much heavier dose compared to that required by PMMA resist. This limits its usefulness to the fabrication of experimental devices. Even so, because of the wide application of SiO₃, the ability to directly write nanoscale patterns in it should enhance the fabrication techniques for ultra-small devices. In this paper, we review the results to date, and compare the SiO₂ process with other nanolithography techniques.