Tuyển tập các báo cáo nghiên cứu về hóa học được đăng trên tạp chí hóa hoc quốc tế đề tài : STEM nanoanalysis of Au/Pt/Ti-Si3N4 interfacial defects and reactions during local stress of SiGe HBTs | Alaeddine et al. Nanoscale Research Letters 2011 6 574 http content 6 1 574 o Nanoscale Research Letters a SpringerOpen Journal NANO EXPRESS Open Access STEM nanoanalysis of Au Pt Ti-Si3N4 interfacial defects and reactions during local stress of SiGe HBTs Ali Alaeddine f Cécile Genevois1 Laurence Chevalier and Kaouther Daoudt Abstract A new insight on the behavior of metal contact-insulating interfaces in SiGe heterojunction bipolar transistor is given by high-performance aberration-corrected scanning transmission electron microscopy STEM analysis tools equipped with sub-nanometric probe size. It is demonstrated that the presence of initial defects introduced during technological processes play a major role in the acceleration of degradation mechanisms of the structure during stress. A combination of energy-filtered transmission electron microscopy analysis with high angle annular dark field 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. High current densities and related local heating effects induce the evolution of the pure Ti initial layer into mixture layer composed of Ti O and N. Local contamination of Ti layers by fluorine atoms is also pointed out as well as rupture of TiN thin barrier layer. Keywords HBT STEM-HAADF EDS EFTEM failure reliability Introduction The metal contact structures are important parts of the transistors in term of device performances with the current losses and signal time delays. It needs to have optimal properties with high contact conductivity and thermo-dynamical stability to prevent contact degradation 1 . The demands for material failure analyses using high-resolution transmission electron microscopy are rapidly increasing to detect smaller defects and perform their chemical element analysis. The Ti Pt Au metal system continues to hold a place of choice .
