CIPM MRA COMPARISON REPORTS

A supplementary comparison (SC) on the measurement of film thickness using X-ray Reflectivity (XRR) was conducted within TCMM/APMP, as proposed and approved at the TCMM/APMP meeting in Singapore in 2018 and the TCMM-TCL/APMP joint meeting in Sydney 2019. The aim of this SC to perform an inter-laboratory comparison of nanoscale film thicknesses measurements by XRR among NMIs and to confirm the international equivalence of the reported measurement results.

Four NMIs - CMS, NIM, NMIJ, and KRISS - participated in the comparison using three specimens comprising single-layer and multilayer thin films with nominal thicknesses from 3 nm to 5 nm. The participating NMIs measured and reported film thicknesses values together with their associated measurement uncertainty. Comparison reference values (CRVs) were determined using an uncertainty-weighted mean method, and the degree of equivalence (DoE) and normalized error (E _n) values were evaluated.

The analysis of all specimens - specimens 1 and 2 consisting of single-layer HfO₂ films and specimen 3 being a multilayer AlAs/GaAs superlattice - demonstrated that the reported thickness measurements are mutually equivalent within their stated uncertainties.

Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.

The final report has been peer-reviewed and approved for publication by the CCL, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).