Creating nanostructures on silicon using ion blistering and electron beam lithography

We have investigated the patterning of silicon surfaces using ion blistering in conjunction with e-beam lithography. Variable width (150-5000 nm) trenches were first written in 500 nm thick PMMA resist spin coated on silicon, using an electron beam. Next, 10 keV H ions were implanted to various fluences through the masks. The resist was then removed and the samples were rapidly thermally annealed at 900 °C. The resulting surface morphologies were investigated by atomic force microscopy. In the wider trenches, round blisters with 600-900 nm diameter are observed, which are similar to those observed on unmasked surfaces. In submicron trenches, there is a transition in morphology, caused by the proximity to the border. The blisters are smaller and they are densely aligned along the trench direction ('string of pearls' pattern). Unusual blister geometries are observed in the narrowest trenches (150 nm) at higher H doses (≥1 × 10 H cm ) - such as tubular blisters aligned along the trench. It was also found that for H doses of ≥6 × 10 H cm the surface swells uniformly, which has implications for the blistering mechanism. The prospects for accomplishing ion cutting, layer transfer and bonding of finely delineated patterns of silicon onto another material are discussed in the light of the above results. © 2006 IOP Publishing Ltd.