Nanometer-scale pattern transfer using ion implantation

Conventional, broad-area, ion implantation has been combined with unconventional masking to create 2-D geometrical patterns of amorphization in single crystals, with selectable motifs. The patterns are fully developed by use of selective etching. Two examples are discussed. In the first example, a self-assembled array (with lattice spacing ∼1 μm) of silica spheres is used as an implant mask over InP. The variation of the mask thickness created by the sphere geometry modulates the implantation depth in a periodic fashion, which is subsequently revealed after selective etching of the associated amorphized volumes. In the second example, nanochannel arrays in an alumina film are used as an implant mask to produce a hexagonal closed packed array of amorphized cylinders in InP and SrTiO₃ substrates. The ion beam-amorphized regions of the substrate are then removed by selective chemical etching to achieve the full 3-D patterning of 55 nm diameter holes on a 100 nm lattice spacing.