The Benefit of Wide Energy Range Spectrum Acquisition During Sputter Depth Profile Measurements

TL;DR

This paper demonstrates that acquiring wide energy range spectra during sputter depth profiling enhances elemental detection and data accuracy, especially for unknown or insulating samples with variable surface potentials.

Contribution

It introduces the use of wide energy range spectra in sputter depth profiling, improving elemental analysis and data correction capabilities for complex samples.

Findings

Wide energy spectra enable detection of all elements in unknown samples.

Re-adjustment of energy scale improves data accuracy for insulating samples.

Demonstrated benefits in practical sputter depth profile measurements.

Abstract

Thin film systems are often analysed by using sputter depth profiling. First the sample gets eroded by inert gas ion impact during sputter depth profiling. Then the elemental composition of the freshly unveiled surface is determined by using a surface sensitive analytical method as AES or XPS, for instance. This way the depth distributions of the elements are recorded as a function of sputter time. The time to record the spectral data in a certain sputter depth is kept as short as possible to avoid recontamination of the freshly sputtered surface by adsorption of gas particles from the vacuum during the measurement. Therefore in every sputter depth only those spectral regions are recorded, which belong to the elements expected to be in the sample. But in case the sample composition is entirely unknown, it is indispensable to measure wide energy range spectra. By this approach the depth distributions of all elements are estimated, which are detectable by the used analytical method. The measurement of wide energy range spectra during sputter depth profile acquisition is promising for samples, which are very insulating. If the surface potential varies in different sputter depths, the elemental peaks are shifted in an unpredictable way. If wide energy range spectra are recorded, the energy scale can be re-adjusted afterwards and the data can be re-evaluated. Both use cases are demonstrated exemplarily by sputter depth profile measurements.