Increasingly complex 3D shapes are used as Semicon devices, requiring advanced metrology techniques to monitor production and understand performance of the devices. Atomic force microscopy allows to reach the required sub-nm accuracy by using relatively blunt probes, sensing always in the same direction, but only the top of the 3D shapes can be explored.
This PhD project is part of a larger project in collaboration with TNO (Dutch Organization for Applied Scientific Research) and the semiconductor metrology company Nearfield Instruments, which aims to enable the use of nanotube-based probes to scan the profile on the samples with more challenging topographies. The nanotube probe shape strongly improves how well holes or trenches in the sample can be accessed. However, the slender probes become weaker in lateral direction, while sensitivity in this direction is also needed to thoroughly scan the samples. Within the project, this position focuses on the modelling and simulation of the nanotube-based profiling, whereas the other two work on the control and experimental part of the project.Job Description
This PhD position aims to understand the nonlinear dynamics that drive the probe motion in the neighborhood of high-aspect ratio sample structures. In particular, van der Waals-type attractive forces, electrostatic forces and squeeze-film damping forces will bring a strongly nonlinear force-position dependency, which, in contrast to conventional approaches, cannot be understood by a spherical tip & flat surface approximation. Hence, to derive a proper dynamic model of the probe motion, different important steps need to be performed including
- The development of a 3D force model of the probe tip in the vicinity of the sample.
- Based on the dynamical analysis derived from the force model, developing a two-dimensional sensing capacity where profile information can be obtained in longitudinal as well as in lateral direction of the nanotube probe.
- Consideration of sideways bending and buckling of the narrow probe in the model.
- Experimental validation of the 2D profile sensing.
You will execute this project in the Autonomous and Complex Systems
group of the Dynamics and Control (D&C)
section at the Department of Mechanical Engineering of the Eindhoven University of Technology, and TNO Optomechatronics in Delft.
The mission of the Dynamics and Control Section, which consists of 22 faculty members and 45 researchers, is to perform research and train next-generation students on the topic of understanding and predicting the dynamics of complex engineering systems in order to develop advanced control, estimation, planning, and learning strategies which are at the core of the intelligent autonomous systems of the future: Designing and realizing smart autonomous systems for industry and society.
TNO Optomechatronics develops world-class optomechatronic systems for applications in space, big science, and the semiconductor industry. We push back the boundaries of technology, so as to give impetus to the high-tech industry and enable scientific discoveries.