Microcircuit imaging using an ion-beam-induced charge

Abstract

Ionizing radiation such as photons, keV electrons, or MeV ions can generate electron-hole pairs in semiconducting material. The high penetrating power of MeV light ions allows them to generate electron-hole pairs from deep within intact microelectronic devices, so images can be formed of the device active areas with very little degradation of the spatial resolution of the focused MeV ion beam. Furthermore, the ion-beam-induced charge (IBIC) image contrast is not strongly affected by the energy loss through the overlying device layers. This article is the first to demonstrate the capability of a nuclear microprobe to generate IBIC images of the active regions of devices through the passivation and metallization layers. The effect of the carrier generation volume on IBIC resolution is assessed. The ability of IBIC to align the major crystal axes of semiconductor samples is shown, and the effect of ion-induced damage on IBIC image contrast is considered.