Kalha, Curran;
Thakur, Pardeep K;
Lee, Tien‐Lin;
Reisinger, Michael;
Zechner, Johannes;
Nelhiebel, Michael;
Regoutz, Anna;
(2023)
Capturing the Dynamics of Ti Diffusion Across Ti
<sub>x</sub>
W
<sub>1−x</sub>
/Cu Heterostructures using X‐Ray Photoelectron Spectroscopy.
Advanced Physics Research
10.1002/apxr.202300008.
(In press).
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Abstract
Interdiffusion phenomena between adjacent materials are highly prevalent in semiconductor device architectures and can present a major reliability challenge for the industry. To fully capture these phenomena, experimental approaches must go beyond static and post-mortem studies to include in situ and in-operando setups. Here, soft and hard X-ray photoelectron spectroscopy (SXPS and HAXPES) is used to monitor diffusion in real-time across a proxy device. The device consists of a Si/SiO2/TixW1−x(300 nm)/Cu(25 nm) thin film material stack, with the TixW1−x film (x = 0.054, 0.115, 0.148) acting as a diffusion barrier between Si and Cu. The interdiffusion is monitored through the continuous collection of spectra whilst in situ annealing to 673 K. Ti within the TiW is found to be highly mobile during annealing, diffusing out of the barrier and accumulating at the Cu surface. Increasing the Ti concentration within the TixW1−x film increases the quantity of accumulated Ti, and Ti is first detected at the Cu surface at temperatures as low as 550 K. Surprisingly, at low Ti concentrations (x = 0.054), W is also mobile and diffuses alongside Ti. By monitoring the Ti 1s core level with HAXPES, the surface-accumulated Ti was observed to undergo oxidation even under ultra-high vacuum conditions, highlighting the reactivity of Ti in this system. These results provide crucial evidence for the importance of diffusion barrier composition on their efficacy during device application, delivering insights into the mechanisms underlying their effectiveness and limitations.
| Type: | Article |
|---|---|
| Title: | Capturing the Dynamics of Ti Diffusion Across Ti <sub>x</sub> W <sub>1−x</sub> /Cu Heterostructures using X‐Ray Photoelectron Spectroscopy |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1002/apxr.202300008 |
| Publisher version: | https://doi.org/10.1002/apxr.202300008 |
| Language: | English |
| Additional information: | This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third-party material in this article are included in the Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/ |
| Keywords: | Diffusion barriers, HAXPES, metallisation, power electronic devices, SXPS, XPS |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Chemistry |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10171584 |
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