Instead of using a solid mask to pattern a light beam (optical lithography) we used a mask made of light to pattern a beam of neutral atoms (atom lithography). By making use of two special features of the atom-light interaction we wrote structures with periods below λ/2. In the first approach we inverted the focussing potentials by switching the detuning of the light field during the deposition. The second method uses the fact that atoms with a magnetic substructure in the electronic ground state are strongly sensitive to the polarization of the light field. Both techniques produce sub-100 nm chromium structures in one and two dimensions on silicon substrates.