A THEORY OF ION-BEAM-INDUCED CHARGE COLLECTION

The ion beam induced charge technique can image the depletion regions of microelectronic devices through their thick metallization and passivation layers, and buried dislocation networks in semiconductor material by measuring the number of charge carriers created by a focused MeV light ion beam scanning over the sample surface. In this paper it is shown how the charge pulse height can be calculated in terms of the ion type and energy, and the minority carrier diffusion length. The effect of surface layers, depletion layers, ion induced damage, and ion channeling on the measured charge pulse height are also considered. It is shown how this approach can be used to simulate the charge pulse height reduction due to ion induced damage.