An investigation of redeposition effect for deterministic fabrication of nanodots by focused ion beam

Focused ion beam machining is a powerful technique for micro/nanofabrication. However its machined surface form accuracy will be degrade due to atoms redeposition in the nanofabrication process. In this paper, a 3D surface topography model and associated simulation program are developed to study redeposition effect for precise and deterministic fabrication of nanodots by focused ion beam. The simulation is implemented by level set method. The angular dependence of sputtering yield is calculated by a Monte Carlo simulation program – TRIDYN. The simulation results have been evaluated by focused ion beam fabrication of nanodots experiment on a silicon substrate. It demonstrates that the simulation method can precisely describe the generation of 3D surface in focused ion beam machining process (with less than 10% simulation error). Redeposition has made significant contribution to the surface generation in nanoscale fabrication by reducing more than 1/3 of intended depth. The model and simulation program developed has approved to be a good tool to determine proper machining parameter to achieve deterministic nanofabrication by focused ion beam.