Round Robin: Composition And Thickness of Nitride and Oxide Thin Films Grown by Atomic Layer Deposition

A round robin characterization of the elemental composition and thickness of Al₂O₃ and TiN thin films using IBA methods was organized. The samples were grown by atomic layer deposition (ALD) on 200 mm Si wafers. The Al₂O₃ films with different thicknesses (10–100 nm) were deposited using Al(CH₃)₃ and water as precursors at low temperatures, known to produce films with high impurity concentrations and non-stoichiometric O/Al ratio. The TiN films, sandwiched between thinner ALD-Al₂O₃ films, were grown using TiCl₄ and NH₃ precursors. The samples were chosen to represent a typical thin film analysis problem with real-world applications.

The participating institutes were mainly using heavy ion elastic recoil detection analysis (HI-ERDA) as a single measurement technique capable of providing all the requested information. Rutherford backscattering spectrometry (RBS) and nuclear reaction analysis (NRA) were employed as multi-technique complementary analysis (so called Total-IBA) or to give partial results. In addition, X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS) were employed as complementary techniques.

The main goal of this study was not to promote the HI-ERDA technique but to identify the possible weaknesses and limitations of different analysis techniques and approaches, and thereafter improve the accuracy and reliability of the results given by the ion beam analysis community. A special emphasis was put on transparency of the results obtained – all the raw measurement data are publicly available for e.g. comparison and educational use via open data portal.