MasterNanosciences, nanotechnologies

PhD position 2024-2027
Funded by ST Microelectronics (PhD Cifre)
Supervisors: Dr Bureau, Dr Bayart and Dr Loreanceau - LiPhy Grenoble
                       Dr Garnier - ST Microelectronics

Context

The increasing miniaturization of electronic circuits allows - in addition to an obvious reduction in size - to manufacture more efficient, faster components and achieve substantial gains in electricity consumption. However, it also imposes increasingly restrictive conditions on particle size likely to contaminate electronic components: today all particles with diameters greater than 10 nanometers are potentially harmful to microelectronic circuits. To meet these challenges, the cleaning processes – which are an integral part of microelectronics production chains – must be more and more efficient (i.e. remove particles from a few nanometers in diameter) and versatile (i.e. be effective on surfaces hydrophilic or hydrophobic), while respecting new environmental standards. Cleaning processes using the removal of a  polymer film encapsulating the particles to be eliminated, are identified as promising [Lallart], but remain today poorly understood. The delamination of thin films has been a subject of active research in recent years, for technological reasons such as the development of deformable electronics, or the control of manufacturing processes [Kim], but also for fundamental reasons such as the study of mechanical instabilities, the study of couplings between elastic and adhesion properties,  or the study of geometrically frustrated elastic systems [Vella]. To date, only homogeneous adhesive interfaces were considered in the studyies of delamination. The objective of this thesis is to study this process in the presence of a 3rd body, that is to say, solid particles present at the interface between the polymer and the substrate.

Objective of the project

During this thesis an experiment of polymer thin film delamination will be developped,  by depositing a template polymer on a surface previously contaminated with particles. We will consider different types of loading: loading in compression inducing the formation of blisters, or in tension, causing the film to break (see figure). In both cases, either the appearance of fractures or blisters, a fraction of the surface peels off. The impact of the presence of particles adhering to the film on the stress fields and on delamination processes will be studied. We will seek to quantify and optimize particle removal by the different methods considered and study the limits of each of them depending on the range of parameters accessible. By counting the particles initially and finally present on the surface, we will be able to characterize the effectiveness of the process, in particular depending on particle/surface adhesion. The thesis work will also adress the modeling of the delamination mechanism in the presence of particles, in relation with the experimental results obtained, using existing models of adhering solids with dissimilar elastic properties

Possible mechanisms inducing particle removal. a) At the top the polymer film loaded with particles is placed under tension. At the bottom, the film delaminates over an area A following the propagation of a fracture perpendicular to the observation plane. b) At the top, the polymer film loaded with particles is compressed. At the bottom, a blister of area A appears, inducing delamination of the film.

Profile of the candidate

Training in physics or mechanics is preferred, with an interest in physical chemistry, soft matter, elasticity and a strong motivation for experimental research.

References

• Lallart, A. et al. (2018) Cleaning surfaces from nanoparticles with polymer film: impact of the polymer stripping, Micro and Nano Engineering 1:33-322
• Kim DH, et al. (2008) Stretchable and foldable silicon integrated circuits. Science 320:507–511.
• Vella, D., Bico, J., Boudaoud, A., Roman, B., Reis, P. M. (2009) The macroscopic delamination of thin films from elastic substrates. Proceedings of the National Academy of Sciences 106:10901-10906.