Development of the IBIC (Ion Beam Induced Charge) technique for IC failure analysis

Abstract

IBIC imaging of buried structures of semiconductor devices is carried out with a scanned focussed MeV ion beam (eg protons, molecular hydrogen ions or alpha particles). The large range of these ions (eg 47 μ:m for 2 MeV protons in Si) allows direct imaging of sub-surface structures through passivation layers, a feature not available to the well established EBIC (Electron Beam Induced Current) technique. As multi-level designs become more prevalent this deep penetration is a significant advantage. The nuclear microscope is briefly described here. Recent examples of the IBIC analysis of CMOS and diffused junction devices are given, and the degradiation of IBIC images with increasing ion dose is discussed. It is demonstrated that contrast is present in IBIC images even from junctions not directly connected to the preamplifier. The production of significant charge signals from unconnected junctions allows the imaging of such junctions, a highly desirable feature in the case of complex microcircuits. The contrast from unconnected junctions vanishes if these junctions are shortened, as will be shown.