Topic
Chemical state
About: Chemical state is a research topic. Over the lifetime, 2378 publications have been published within this topic receiving 78183 citations.
Papers published on a yearly basis
Papers
More filters
••
TL;DR: In this article, a combined soft and hard X-ray photoelectron spectroscopy (XPS) approach is used to study the influence of post-deposition annealing and titanium concentration on the oxidation behavior of a 300~nm-thick TiW film.
Abstract: The binary alloy of titanium-tungsten (TiW) is an established diffusion barrier in high-power semiconductor devices, owing to its ability to suppress the diffusion of copper from the metallisation scheme into the surrounding silicon substructure. However, little is known about the response of TiW to high temperature events or its behaviour when exposed to air. Here, a combined soft and hard X-ray photoelectron spectroscopy (XPS) characterisation approach is used to study the influence of post-deposition annealing and titanium concentration on the oxidation behaviour of a 300~nm-thick TiW film. The combination of both XPS techniques allows for the assessment of the chemical state and elemental composition across the surface and bulk of the TiW layer. The findings show that in response to high-temperature annealing, titanium segregates out of the mixed metal system and upwardly migrates, accumulating at the TiW/air interface. Titanium shows remarkably rapid diffusion under relatively short annealing timescales and the extent of titanium surface enrichment is increased through longer annealing periods or by increasing the precursor titanium concentration. Surface titanium enrichment enhances the extent of oxidation both at the surface and in the bulk of the alloy due to the strong gettering ability of titanium. Quantification of the soft X-ray photoelectron spectra highlights the formation of three tungsten oxidation environments, attributed to WO$_2$, WO$_3$ and a WO$_3$ oxide coordinated with a titanium environment. This combinatorial characterisation approach provides valuable insights into the thermal and oxidation stability of TiW alloys from two depth perspectives, aiding the development of future device technologies.
7 citations
••
7 citations
••
TL;DR: In this article, the X-ray absorption fine structure (XAFS) spectroscopy was used to analyze the chemical state conversion of the Ni species in SiO2-supported Ni catalysts which were prepared by the impregnation me...
Abstract: The X-ray absorption fine structure (XAFS) spectroscopy was used to analyze the chemical state conversion of the Ni species in SiO2-supported Ni catalysts which were prepared by the impregnation me...
7 citations
••
TL;DR: In this article, chemical state analysis was carried out for model molecules of natural rubber (2-methyl-2-butene and isoprene) adsorbed on Cu2S, a key chemical species for adhesion, by means of photoelectron spectroscopy.
7 citations
••
TL;DR: In this article, the authors show that Al3FeH3.9 is more thermodynamically stable than AlH3, and it is likely that the mixing of the chemical states of hydrogen atoms is the source of increased stability.
7 citations