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 control for the nanotube-based profiling, whereas the other two work on the modelling and experimental part of the project.

Job Description

This PhD Position aims to provide the control techniques required to keep the probe in proximity of the sample and to ensure that the metrology objectives are achieved. Control challenges on the nanotube-based profiling include 1) navigation of the probe towards the point of interest on the sample; 2) facilitating 2D profile sensing and selecting the correct sensing direction for this part of the sample; and 3) profile reconstruction based on measurement signals. You will contribute to these challenges by

• The design of controllers that, using real-time measurements,  generate a path along the sample profile and optimize the sensing direction to ensure that enough profile measurements are generated along the sample contour, minimizing blind spots.
• The development of estimation technique exploiting the known stage dynamics, as well as the modelled probe dynamics, to provide highly accurate profile information.
• Demonstrating (elements of) the developed control concepts on an existing AFM.

Embedding

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.