The necessity of miniaturization of the devices expands the scope of nanotechnology. In recent years, researchers have poured in a lot of effort in the development of nanoscale devices. The focused ion beam (FIB) has proven itself as a very powerful and unique technique for nanofabrication. FIB induced micro / nanofabrication fundamentally involves two basic phenomena namely sputtering and molecular cracking, leading to the material removal and material deposition, respectively. In the present work the basic physical processes involved in the FIB induced deposition have been investigated and the correlation between ion beam parameters and physical characteristics of FIB fabricated nanostructures has been studied. There are a number of other physical phenomena viz. scattering, redeposition, secondary electron / photon emission and localized heating etc. which may occur when the incident ions interact with the substrate during the FIB processing, and intricately influence the nanofabrication. Therefore, it is very necessary to investigate the effect of these phenomena for efficient FIB processing. In the present work the influences of these physical phenomena have been explored.