Are you an engineer who wants to contribute to the high-tech, state-of-the-art micromechanical experimental analysis of microscopic wear of silicon during wafer handling? We are looking for an outstanding and enthusiastic PhD candidate, with a strong experimental mechanics profile of excellence, to work on a challenging micro-mechanical testing project, in an exciting multidisciplinary team.
Context The yield of many manufacturing processes of micro- and nanoscale substrates depends highly on their cleanliness. Reduction of contaminating particles improves the overall efficiency and quality, thereby enabling the creation of larger structured substrates. Investing in the prevention of wear particles generation is a way to tackle this issue directly at the source, which is particularly relevant for wafer handling.
Silicon is a very complex material, undergoing multiple phase transformation, with some phases showing extensive plastic deformation, during mechanical loading and contact. The generation of particles is rooted in the complex fracture events spanning the various phases of silicon in various 3D stress configurations. A predictive model should properly account for the complex physics, damage and fracture. The loading conditions in contact and scratching are equally complex and need to be properly accounted for as well.
PhD project The objective of this project is to extensively characterize the governing micromechanisms of phase transformation, plasticity, damage and fracture during the silicon particle detachment under contact conditions, enabling a quantitative assessment of the dominant influence factors and possible mitigation routes to control the detachment process. To achieve this goal, the project will use a dedicated in-situ scratch tester with in-situ scanning electron microscopy observation capabilities, which so far was used for indentation of silicon with only preliminary exploration of in-SEM scratching.
Building upon the preliminary in-situ SEM scratch exploration, the following extensions and improvements need to be made:
- Develop a method to measure the extent of silicon phase transformation and plasticity underneath a silicon micro-scratch, using electron backscatter diffraction or transmission Kikuchi diffraction on focused ion beam lift-outs of the scratch.
- Develop a method to quantify the volume and size distribution of wear particles, based on in-SEM scratch movies combined with atomic force microscopy of the corresponding scratches.
- Combine these methods to quantify phase transformation, plasticity, damage, fracture, and particle volume/sizes for the parameters space that is relevant for wafer handling.
- Map out the different regimes of silicon deformation and particle generation and formulate and validate a mitigation strategy to reduce particle generation.
- Determine the input parameters for the predictive modelling framework being developed in the numerical co-project, e.g. material parameters and the friction coefficient in the different scratch regimes.
The experimental campaign will be guided by the insights from numerical simulations. The interaction between the experimental project and the parallel modelling project, focused on simulating particle generation in silicon wafers, is therefore essential.
Section Mechanics of Materials You will work in the section of Mechanics of Materials (MoM) (
www.tue.nl/mechmat) at the department of Mechanical Engineering of Eindhoven University of Technology (TU/e). The MoM section is recognized worldwide for its high-level research on experimental analysis, theoretical understanding and predictive modelling of complex mechanical behavior in engineering materials at different length scales (e.g, plasticity, damage, fracture), which emerges from the physics and mechanics of the underlying multi-phase microstructure. An integrated numerical-experimental approach is generally adopted for this goal.
A state-of-the-art micromechanical testing infrastructure is in place for the experimental work in this project (
www.tue.nl/multiscale-lab).