Combined Pulsed RF GD-OES and HAXPES for Quantified Depth Profiling through Coatings

Muriel Bouttemy,Solène Béchu,Patrick Chapon,Arnaud Etcheberry,Ben F Spencer,Pia Dally

doi:10.3390/coatings11060702

Abstract

Chemical characterization at buried interfaces is a real challenge, as the physico-chemical processes operating at the interface govern the properties of many systems and devices. We have developed a methodology based on the combined use of pulsed RF GD-OES (pulsed Radio Frequency Glow Discharge Optical Emission Spectrometry) and XPS (X-ray Photoelectron Spectroscopy) to facilitate the access to deeply buried locations (taking advantage of the high profiling rate of the GD-OES) and perform an accurate chemical diagnosis using XPS directly inside the GD crater. The reliability of the chemical information is, however, influenced by a perturbed layer present at the surface of the crater, hindering traditional XPS examination due to a relatively short sampling depth. Sampling below the perturbed layer may, however, can be achieved using a higher energy excitation source with an increased sampling depth, and is enabled here by a new laboratory-based HAXPES (Hard X-ray PhotoElectron Spectroscopy) (Ga-Kα, 9.25 keV). This new approach combining HAXPES with pulsed RF GD-OES requires benchmarking and is here demonstrated and evaluated on InP. The perturbed depth is estimated and the consistency of the chemical information measured is demonstrated, offering a new route for advanced chemical depth profiling through coatings and heterostructures.

Highlights

This study demonstrates how pulsed RF GD-OES coupled with HAXPES may be employed to fast access to deeply buried layers of complex stacks and buried associated interfaces and to chemically characterize below the GD damage layer with a non-destructive analysis
The composition inside a GD crater has been measured by means of photoemission using two excitation sources: Al Kα emitting at 1.49 keV (XPS) and Ga Kα 9.25 keV
The combined use of XPS and HAXPES enables a complete investigation of the composition inside the crater, knowing that previous results have already demonstrated the presence of a perturbed overlayer inherent to the GD profiling interruption

Summary

Introduction

Microelectronic or photovoltaic devices are constituted of successive layers, the structure of which is intensively studied to improve the efficiency and/or the robustness of the components. Among the different methods to access the buried interfaces and specific areas of interest, pulsed RF GD-OES (pulsed Radio Frequency Glow Discharge Optical Emission Spectroscopy) leads to an accurate chemical diagnosis during fast depth profiling through coatings and interfaces over several tens of microns [1]. This rapid profiling capability, can quickly yield to the chemical repartition when analyzing coated structures or stacks. The quantification from the pulsed RF GD-OES light intensities to atomic concentrations is not straightforward when a material system involves many elements and requires a calibration step

Methods

Results

Conclusion