Au/Pt/Ti-Si3N4 interfacial defects analysis of a stressed SiGe HBT by using STEM nanometric characterization

This work attempts to reveal, by high-performance scanning transmission electron microscopy (STEM) nanoanalysis, the failure mechanisms at the Au/Pt/Ti/Si₃N₄ interface during local stress of SiGe HBT (Silicon Germanium Heterojunction Bipolar Transistor). We demonstrated that the presence of initial defects introduced during technological processes play a major role in the acceleration of degradation mechanisms during stress. A combination of energy-filtered transmission electron microscopy analysis STEM and energy dispersive spectroscopy provides strong evidence that migration of Au-Pt from the metal contacts to Ti/Si₃N₄ interface is one of the precursors to species interdiffusion and reactions. This analysis has permitted a comprehensive study of the failure mechanisms in an HBT structure submitted to local stress inducing heating effects.