Disordered intermixing at the platinum:silicon interface demonstrated by high-resolution cross-sectional transmission electron microscopy, Auger electron spectroscopy, and MeV ion channeling

The metallurgical interaction at the interface between single-crystal silicon substrates and thin films of elemental platinum has been examined using the complementary techniques of high-resolution cross-sectional transmission electron microscopy (HRXTEM), Auger sputter profiling, and MeV ion channeling. We identify the existence of a 30-Å-thick layer of intermixed platinum and silicon which forms at the metal-silicide interface when 50 Å of Pt is electron beam evaporated onto room-temperature Si. The interfacial layer is evident in the HRXTEM as a uniform band of dark and noncrystalline contrast. In Auger sputter profiling, the evolution of the Si LVV line shape indicates the presence of a platinum silicide region adjacent to the film/Si interface but not at the surface of the Pt film. MeV ion channeling reveals that ∼1.5×10¹⁶ Si atoms/cm² are displaced from their substrate lattice sites upon Pt deposition. In addition, the HRXTEM reveals islands of unreacted Pt and occasional grains of Pt₂Si on top of the intermixed layer of Pt and Si.