<title>Using neutral metastable argon atoms and contamination lithography to form nanostructures in silicon, silicon dioxide, and gold</title>

We describe the fabrication of approximately 70-nm structures in silicon, silicon dioxide, and gold substrates by the exposure of the substrates to a beam of metastable argon atoms in the presence of dilute vapors of trimethylpentaphenyltrisiloxane, the dominant constituent of the diffusion pump oil used in these experiments. The atoms release their internal energy upon contacting the siloxanes physisorbed on the surface of the substrate, and this release causes the formation of a predominantly carbon-based resist. To demonstrate the resolution of the resist formation process, the atomic beam was patterned by a silicon nitride membrane, and the pattern formed in the resist material was transferred to the substrates by chemical etching. Simultaneous exposure of large areas (44 cm²) was also demonstrated. The sensitivity of the resist formation to the internal energy stored in the atom allows a new pattern formation technique based on spatially dependent optical de-excitation of the metastable atoms.