Magnetic hexapole lens focusing of a metastable helium atomic beam for UV-free lithography

Sources of rare gas atoms in excited metastable states have been used to expose photoresist-coated substrates to demonstrate atom lithography. These thermal atomic beams are usually created by discharge sources that also produce copious amounts of UV radiation. The UV radiation simultaneously illuminates the substrate and may play a complementary role in altering the photoresist together with the metastable atoms. In the experiments reported here, we have isolated the UV component using a magnetic hexapole lens to focus a thermal beam of metastable helium atoms around a fiducial mask that blocks the UV light. This creates an atom lithography exposure that is the result of illumination by the atoms alone. We have also modelled the performance of the magnetic hexapole lens as a potentially useful device for atom lithography. PACS 39.25.+k; 81.16.Nd