Practical Electron Microscopy and Database

When an ion beam impinges on a surface in FIB (focused ion beam) milling or deposition, it transfers its kinetic energy mostly by the way of electronic excitations and collisions, which eventually gets converted to the form of heat, resulting in rise of the local temperature. The local temperature rise (Θ) in Si, GaAs, and SiO₂ bulks in focused-ion-beam (FIB) sample preparation at a beam energy of 30 keV had been calculated [1] based on the model for laser beam heating proposed by Nissim et al. The FIB-heated region was in a hemispheric shape. Θ_max of less than 100 K were predicted for the three materials. In their modeling, I/d is 20 nA/μm at maximum. Here, I was beam density and d is the beam diameter. Θ_max for SiO₂ sample is larger by about 100 times than that for Si sample because of its low thermal conductivity and diflusivity of heat.