Inter-Laboratory Comparison (ILC) Study for MEIS

Medium Energy Ion Scattering Spectrometry (MEIS) is a technique that analyzes the compositional depth profile of samples with a thickness of 2 nm–50 nm using 100–500 keV hydrogen or helium ions. As thin films become widely used in industry, the demand for MEIS analysis is increasing, and MEIS is gaining attention with this trend. When new analytical technologies are applied to industrial sites, standardization is essential to ensure the reliability of the analysis.

For this purpose, an inter-laboratory comparison (ILC) study on MEIS analysis of HfO₂ samples was conducted from 2015 to 2017 involving 12 participating institutions. As a result, it was concluded that the most valid results are obtained when analyzing based on measured stopping cross section, and this conclusion was established as an ISO standard (ISO23170).[1]

Following this standard for MEIS analysis, an ILC study regarding measurement conditions has been underway since 2023 with a total of 8 institutions participating. Hf_xZrO_y samples (x = 1, 2, 3, 4, 5, y = (x+1) ´ 2) were fabricated using atomic layer deposition. Samples were distributed after verifying their uniformity using a spectral ellipsometer. In this ILC, four parameters - beam energy, scattering angle, MCP detector voltage, and no multi-hit conditions at detector - were set as the primary measurement conditions. Additionally, to minimize deviations of analysis results caused by simulation models such as stopping cross section and screening, 100–150 keV He⁺ ions, an incidence of 0 ^o, and a scattering angle of 120–135^o were recommended.

In this research, the quantity of Hf and Zr, as well as the composition and thickness of Hf_xZrO_y, submitted by participants were analyzed. Through this, we aim to establish a standard for parameters for valid measurements.

References.

[1] ISO 23170, Surface chemical analysis — Depth profiling — Non-destructive depth profiling of nanoscale heavy metal oxide thin films on Si substrates with medium energy ion scattering