MeV Ion Beam Synthesis of Nanopore Arrays in SiO2 Films

High energy (MeV), heavy ion irradiation can be used as a tool to deform patterned SiO$_{2}$ films in a controlled fashion. We have used this technique to deform micron-sized holes in SiO$_{2}$ films generated by photolithography and focused ion beam milling. The holes were fabricated in 2 $\mu $m thick SiO$_{2}$ films in the size range from 500 nm to 2 $\mu $m and were subsequently irradiated with 4 MeV Xe$^{ }$ions. First, a systematic study will be presented on the deformation of differently shaped holes as a function of the ion fluence. Second, we will present data on the deformation of linear and two-dimensional arrays of holes. Finally, we will test the observed deformations against currently available visco-elastic models that describe this ion irradiation-induced deformation process. This work may find application in nanoscale fashioning of SiO$_{2}$ surface features and the controlled fabrication of nanopore arrays.