Measurement of SiGe composition in 3-D semiconductor Fin Field Effect Transistor devices

Abstract

A Transmission Electron Microscopy (TEM)-based method is suggested to measure the composition of SiGe in 3-D structures using Electron Energy Loss Spectroscopy (EELS). The method accounts for the presence of films other than SiGe within the TEM lamella in the electron beam direction. The partial cross section of inelastic scattering of Ge was calibrated using a reference structure, which was earlier analyzed by Electron Energy Dispersive X-ray Analysis (EDX) and Secondary Ion Mass Spectrometry. The composition of SiGe in the p-FET Fin Field Effect Transistor devices with the overlaying Si oxynitride films was measured as a demonstration of the method. We show that the application of EELS yields smaller measurement errors of the SiGe composition as compared to EDX. The effect of beam damage in thin SiGe films surrounded by Si oxynitride is evaluated and compared to the blanket Si/SiGe structures. The method can be applied to the development of novel devices and state-of-the-art processes where the composition of SiGe plays a critical role.