Direct-wire atomic layer deposition of high-quality Pt nanostructures : selective growth conditions and seed layer requirements

Electron beam-induced deposition (EBID) enables the direct-write patterning of metallic structures with sub-10 nm lateral resolution without the use of resist films or etching/lift-off steps but generally leads to material of poor quality and suffers from a low throughput. These shortcomings were mitigated in recent work by combining EBID with atomic layer deposition (ALD). This direct-write ALD technique comprises the patterning of a thin seed layer by EBID followed by selective thickening of the pattern by ALD. In this work, the throughput of direct-write ALD was drastically improved based on new insights into how the ALD growth initiates on EBID material, and in addition, the conditions for selective ALD growth were identified. The required electron dose was reduced by 2 orders of magnitude to 11 pC/µm2 by exposing the EBID seed layers to O2 in the ALD reactor just before the ALD building step. This improvement of the technique allows for nanopatterning with a throughput comparable to electron beam lithography (EBL)