Modelling of focused ion beam induced increases in sample temperature: a case study of heat damage in biological samples

Ion beam induced heat damage in soft materials and biological samples is not yet well understood in Focused Ion Beam systems (FIBs). The work presented here discusses the physics behind the ion beam – sample interactions and the effects which lead to increases in sample temperature and potential heat damage. A model by which heat damage can be estimated and which allows parameters to be determined that reduce/prevent heat damage was derived from Fourier’s law of heat transfer and compared to finite element simulations, numerical modeling results and experiments. The results suggests that ion beam induced heat damage can be prevented/minimized by reducing the ion beam current (local dose rate), decreasing the beam overlap (reduced local ion dose) and by introducing a blur (increased surface cross-section area, reduced local dose) while sputtering, patterning or imaging soft material and non-resin-embedded biological samples using FIBs.