Tutorial on interpreting x-ray photoelectron spectroscopy survey spectra: Questions and answers on spectra from the atomic layer deposition of Al2O3 on silicon

Abstract

X-ray photoelectron spectroscopy (XPS) has become the most widely used method for chemically analyzing surfaces. In XPS, photoelectrons are generated by irradiating a surface with x rays. As the importance and popularity of XPS have grown, it has drawn users without significant XPS experience, and incorrect and incomplete interpretations of XPS spectra regularly appear in the literature. This tutorial is designed as a tool to guide less experienced users in analyzing XPS survey spectra. Here, the authors examine a series of XPS survey spectra collected during the atomic layer deposition (ALD) of Al2O3 from trimethylaluminum and water precursors. Prior to this, brief explanations of XPS and ALD are presented. This tutorial is structured as a series of questions and answers that the interested reader may choose to engage in. The XPS spectra are scrutinized to extract information about the elements present in the film, the presence of contamination, and the nature of the film growth process. The questions and answers in this tutorial address important fundamental issues common to the interpretation of many XPS survey spectra in the context of ALD.

Proliferation of Faulty Materials Data Analysis in the Literature

“…A more detailed analysis of the current problems in XPS data analysis, along with specific actions that can be taken to address the issues, is forthcoming. Some of us are in the process of writing a series of guides, tutorials, and recommended protocol articles on XPS that are being published in the Journal of Vacuum Science and Technology (Shah et al, 2018;Baer et al, 2019). We believe that these will be an aid to those who wish to acquaint themselves with the technique, so that they can avoid some of the common pitfalls in XPS data analysis and reporting.…”

Practical guides for x-ray photoelectron spectroscopy: First steps in planning, conducting, and reporting XPS measurements

“…The first document to appear was a tutorial on interpretation of XPS survey spectra. 21 Although certainly not the only reason or even a primary cause, the misuse and misinterpretation of XPS data contribute to reproducibility issues in the scientific literature. We note that the U.S. National Academies have established a study group to explore the issues of reproducibility and replication in scientific and engineering research.…”

Multi‐instrument characterization of HiPIMS and DC magnetron sputtered tungsten and copper films

“… Similarly, XPS, a surface sensitive technique, showed only the expected elements (see Supporting Information). XPS measures up to 5 to 10 nm of the top layer of the surfaces. In addition to the expected metal signals, the presence of O 1 s, O KLL Auger, and C 1 s signals indicates a small amount of oxidation of the metals and adventitious hydrocarbon contamination, respectively.…”