Analysis of Ni silicide abnormal growth mechanism using advanced TEM techniques

We performed detailed analysis of the abnormal growth of Ni silicide that causes leakage-current failure in CMOS devices. We investigated the three-dimensional shape and the crystal microstructure of the abnormal growth by using advanced transmission electron microscope (TEM) techniques: electron tomography and spatially-resolved electron energy-loss spectroscopy (EELS). Furthermore, we revealed that the abnormal growth is related to crystal microstructure and crystal defects. This detailed information is important in the mechanism elucidation of abnormal growth of Ni silicide. To develop a highly reliable Ni salicide process, it is essential to understand the failure mechanism of abnormal growths of Ni silicide, especially for 45 nm node devices and beyond. To conclude, we discuss the solutions for the development of a successful Ni salicide process.