Thickness and Composition Measurements of Nanoelectronics Multilayer Thin Films by Energy Dispersive Spectroscopy (EDS)

Scaling is one of the main aspects to continuously improve the performance of nanoelectronic devices. This leads to increasingly more complex stacks including new materials; for example SiO2 is being replaced by high-k materials for gate dielectric applications and metal gates are introduced in place of poly-Si. Moreover, a change in the type of substrate is also considered; Ge and III/V materials are intensively investigated as possible candidates for Si substrate replacement. The introduction of these new materials together with the device downscaling has drastically increased the demand for both composition and thickness metrology methods. Various established techniques providing composition analysis exist such as X-Ray Photoelectron Spectroscopy (XPS) and Rutherford Backscattering Spectrometry (RBS), however, they usually require a large area for the analysis, complex instrumentation and can be time consuming. In this paper, Energy Dispersive Spectroscopy (EDS) coupled to Scanning Electron Microscopy (SEM) is used to determine both composition and thickness of simple and more complex multilayered thin films. The use of EDS for thickness measurements in small scale areas is also investigated.