Direct nanometer scale patterning of SiO₂ with electron beam irradiation through a sacrificial layer

Nanometer scale patterns have been fabricated in SiO₂ by electron beam exposure through a sacrificial layer. Although the process of patterning SiO₂ with direct electron beam irradiation was discovered over two decades ago, the smallest feature size previously achieved was 0.6 μm because finely focused electron beams form a contamination layer on the substrate blocking the subsequent development of the oxide with HF wet etches. Exposing through a sacrificial layer, the contamination is readily removed with the stripping of the sacrificial layer. Using high energy electrons (300 keV) to minimize forward scattering of the beam, arrays of lines with a period down to 21 nm have been fabricated in the SiO₂.