In her PhD research, Cristiane Stilhano Vilas Boas verified major and fundamental aspects of oxygen-thin films interaction. This topic has been studied for many years already, she says. ‘My first reaction was, it will be very hard to find new insights. But our specific experimental approach in a well-defined low-temperature range (298 K – 473 K), in non-aggressive process environments, did certainly lead to scientific findings.’
Cristiane showed that a number of key physical aspects can be directly translated into industrial relevance. For example: in the selection of top layers to better resist oxidation, and for the development of strategies to tackle film degradation and increase device lifetime.
Cristiane: ‘In Brazil, I started as an engineer. Then I decided to pick up a master track in nano-science. Doing so implied a conscious choice for pursuing an academic career. My PhD work shows that the industry can benefit more from looking for a deeper understanding. It is nice to see both my interest fields reflected. I believe the key to the success of my PhD was to use my interdisciplinary skills, integrate knowledge from different fields, and gain a deeper understanding of nanoscale oxidation processes.’
In her research, Cristiane used Low Energy Ion Scattering (Leis) as the main technique to study the dynamics of oxides formation. Leis provides a fast and non-destructive way to measure the atomic composition of the topmost layer of materials, with sub-nanometre resolution.
‘Leis is a relatively new characterization technique,’ Cristiane explains. ‘A new method for non-destructive determination of metal oxide film thickness was validated. Also, we found that the surface concentration of reactive atomic species plays a key role in determining oxidation processes at low temperatures.’
Leis is a fast, straightforward technique with a robust method, also valuable in industrial research. ‘We were able to design reference samples, to objectively compare growth process parameters,’ Cristiane says.
Cristiane’s research was part of a collaboration of the XUV (extreme ultraviolet) Group with Carl Zeiss SMT.
‘At the beginning of the PhD project we met frequently,’ she says. ‘We were able to find a nice balance between studying relevant processes for Carl Zeiss and focusing on fundamental aspects of the work which resulted in scientific publications. Carl Zeiss was not involved in the actual experiments but they followed our report results.’
Using high-tech equipment from the NanoLab was important, for example, Scanning Electron Microscope and Transmission Electron Microscopy. ‘Also I used equipment facilities belonging to the XUV-Group,’ Cristiane says.
‘Of special importance was the synthesizing of thin films, to study the surface processes and isolate them from external influences, in a highly controllable way. In my experiments, working with high-quality vacuum all the way, from the production of the sample to perform the experiments and measurements, was decisive. Within XUV-Group and Mesa+ we have great facilities and expertise to do so.’
After her PhD Defence, Cristiane works as a post-doc at Advanced Research Center for Nanolithography (ARCNL), based in Amsterdam.
‘It is great to perform research and being able to share results and make progress, with colleagues and fellow researchers all over the world. At ARCNL I plan to collaborate with other companies and institutions even more. And indeed, good collaboration with Mesa+ groups and experts will be very welcome, I’m sure.’