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Leader in Integrated ICT Hardware & Systems

Cara-Lena Nies


Together with sponsor Meta, Tyndall celebrates the winners and finalists of the 2021 Postgraduate Publication of the Year.

Despite the continuous pandemic challenges, our students once again showed outstanding discoveries and results as part of their PhD projects, some even opening major new possibilities in their field.

Dr Fatima Gunning, Head of Graduate Studies at Tyndall, praised the entries, saying: "Year on year our students really showcase their outstanding contributions to Tyndall’s Research Excellence through the Postgraduate Research Publication of Year competition. This time, we noticed new entries from students who started their research during pandemic and lockdowns, which were quite disruptive, but their perseverance, endurance and team support paid off with excellent results! Once again we saw early stage PhD students submitting their exceptional publications, so special awards as Rising Stars for 2nd and 3rd years were also included! Congratulations to all!"


Cara-Lena Nies

Cara-Lena Nies


“Control of the Cu morphology on Ru-passivated and Ru-doped TaN surfaces – promoting growth of 2D conducting copper for CMOS interconnect”

1. What encouraged you to submit your application to the 2021 Postgraduate Research Publication of the Year? 

This paper is the biggest piece of work I have done as part of my PhD project. From submitting papers to the competition in the past I knew this would be the ideal opportunity to showcase my hard work.

2. What inspired you to choose the subject of your paper?

This paper is the third in a series of publications on the development of a combined diffusion barrier/liner material. As Copper (Cu) tends to form non-conducting islands at the nanoscale, it is essential to deposit a smooth Cu film with low resistivity to fabricate a functioning interconnect. Based on my insights gained on the interactions of Cu with Ruthenium (Ru)-modified Tantalum nitride (TaN) in my previous research, I wanted to write a paper that would focus on the interactions that control the growth mechanism of Cu on Ru-modified TaN in order to promote a favorable film structure.
3. What’s your paper about and how did you prepare for it? What role did research excellence play in your approach?

This paper presents a new approach to overcome the limits to metal interconnect manufacturing, a significant challenge to CMOS miniaturisation. We proposed Ru-modified TaN as a combined barrier/liner material, with dual function: a diffusion barrier, preventing Cu diffusion from the interconnect into the dielectric, and a liner, promoting 2D conducting Cu instead of non-conducting islands. The industry standard is to use a bilayer of diffusion barrier and liner; however, as transistor size decreases according to Moore’s Law, these additional layers in the interconnect via must be eliminated to allow deposition of conducting Cu. Thinning the barrier/liner allows extended use of Cu as a low-level interconnect metal. Continued use of Cu at higher interconnect levels means that optimising performance and lifetime of Cu interconnects is an important step to continued improvement of device performance. Based on insights from previous work published during my PhD on Ru-modified TaN, the focus of this paper is on understanding the role of Ru in controlling the nucleation of Cu and to demonstrate the mechanisms controlling 2D vs 3D growth. This work presents an important computational methodology through which the growth mechanism and film morphology of a metal on a substrate can be studied. This is highly important outside of the interconnect issue for all surface chemistries where control of the film morphology is required.

4. The selection for Research Publication of the Year is extremely competitive. What is your advice for those aspiring for nomination next year? 

Publishing a paper is something to be extremely proud of. Writing the application is a good way to remind yourself why you did all of that hard work. Whether you have applied before or not, the competition is a great way to bring attention to your research, so there is really no reason not to apply!

5. What is the single most significant support Tyndall has been able to offer you in achieving your research goals? (Please provide any detail on additional supports that assisted? How has Tyndall enabled you to fulfil your potential in this regard?)

I couldn’t have published this paper without the continued encouragement from my supervisor, Michael Nolan,  and the moral support provided by my research group during all of the times when I felt like the finish line was nowhere in sight.

Research Publication Link

Cara-Lena Nies; Suresh Kondati Natarajanb and Michael Nolan, “Control of the Cu morphology on Ru-passivated and Ru-doped TaN surfaces – promoting growth of 2D conducting copper for CMOS interconnect”, Chem. Sci., 2022,13, 713-725.