Sputtering and thermal effect during ion microbeam patterning of polymeric films

The purpose of this article is to investigate the machinability of polymers and the main parameters involved during ion microbeam processing of polymers. Investigations were made for the case of ion microbeam patterning of polyethyleneterephthalate and nylon-6 using a focused ion beam system with a needle type ion source. The extracted beam diameter was 0.2 mu m, the current density on the target was 1.0 A/cm(2), and the beam energy was 30 keV. The removal rate, which shows the number of atoms removed when an ion impinges on the surface, was obtained experimentally. By comparing the removal rate and the theoretical sputtering yield, it became clear that effects other than sputtering have a great influence on the machinability of polymers. Two-dimensional unsteady heat conduction equations were computed using the finite difference method in order to estimate the temperature increment within and around the beam irradiated area. The results show that localized heating and a change of chemical bonding state during ion microbeam processing strongly influence the patterning of polymers. (C) 2000 American Institute of Physics. [S0034-6748(00)54002-7].